E-Posters

Arthroplasty-Cervical

74

P001: Average 8 Year Follow-Up of Primary Cervical Arthroplasty Constructs

Deeptee Jain ¹ , Michael Reiter ¹ , Amir Kucharski ¹ , Colleen Peters ¹ , Lukas Zebala ¹ , Dan Riew ² , and Michael Kelly ¹

¹ Washington University School of Medicine, St. Louis, USA

² Columbia University Medical Center, New York, USA

Introduction: Cervical disc arthroplasty (CDA) is equivalent or superior to fusion (ACDF) for single and two-level degenerative conditions. Investigational device exemption (IDE) trials are subject to selection bias and cognitive dissonance and more data are required to validate the findings. The purpose of this study was to establish long term outcomes, including revision rates and patient reported outcomes (PROs). Materials and Methods: In this retrospective cohort study, a surgical registry was queried for CDA patients from one surgeon between 2003 and 2015. Inclusion criteria were single- or two-level primary CDA. Charts were reviewed for demographic, surgical, and perioperative, and postoperative data. Primary outcome measures were subsequent surgery and neck disability index (NDI). Patients were invited to a follow-up visit or contacted via telephone for assessment. Wilcoxon sign rank test was used to compare preoperative and final postoperative PROs. Risk factors for revision surgery were determined by Cox regression. Results: 83 patients underwent primary CDA. 35 were lost to follow up and 48 (58%) were included at a mean followup of 8.4 years (age: 47.5 years, 49% female, BMI: 29.3 kg/m², FU range 3.2-17.1 years). Indications included radiculopathy (44 patients), myelopathy (3 patient), and myeloradiculopathy (1 patient). 46 patients underwent 1 level CDA, 2 patients underwent 2 level CDA.12 (25.0%) patients underwent another cervical surgery at an average of 4.0 years after the index operation. 7 were revisions at the index CDA level (Recurrent radiculopathy: 3, ossification: 1, infection: 1, performed at outside hospital for unknown indications: 2). 5 patients underwent surgery at an adjacent level (adjacent segment disease: 4 patients, performed at outside hospital for unknown indications: 1). NDI improved from 40.5 preoperatively to 16.7 postoperatively (P < .001). Age < 40 (HR 7.8, 95% CI 1.8-33.3) and increasing BMI (HR 1.15, 95% CI 1.02-1.33) were risk factors for revision surgery. Conclusion: At a mean of 8-year FU, the rate of repeat cervical surgeries after CDA was similar to historical norms for ACDF. Despite these repeat surgeries, substantial NDI improvements were durable. This study provides valuable information on expected long term outcomes of CDA without industry bias.

225

P002: Evaluation of Application First Russian Endoprosthesis for Cervical Arthroplasty

Alexander Eliseev ¹ , Sergey Mlyavykh ¹ , and Andrey Bokov ¹

¹ Privolzhsky Research Medical University, Oncology and neurosurgery, Nizhny Novgorod, Russian Federation

Introduction: Over the past decade, the study of the biomechanics of the cervical spine in degenerative diseases and in the normal has led to a greater understanding of the compensatory mechanisms. This has led to the emergence of various designs of endoprostheses. The work of the first Russian implant for arthroplasty was evaluated in our Department. The purpose of our research is to compare changes in the range of motion (ROM) of the cervical spine after endoprosthesis with a solid endoprosthesis "Endocarbon" in the early postoperative period. Material and Methods: In a single-center retrospective nonrandomized study 15 patients with one- or two-level degenerative disc disease from С_III-C_IV to С_VI-C_VII with clinical manifestations of radiculopathy due to intervertebral disc disease were included. ROM was measured according to the generally accepted method. Results: The study involved 15 people, including 11 women and 4 men; the average age of patients was 50.3 ± 2.5 years. 18 disc endoprostheses were installed; interventions were performed at the level of C_III-C_IV, C_IV-C_V in 1 case, C_V-C_VI in 7 cases, C_VI-C_VII in 8 cases, and, in 1 case, C_VII-Th_I. The average ROM value in the operated segment before surgery was 3.1° ± .8° (confidence interval (CI) 1.8-4.4; 95%), after the intervention—6.4° ± 1.4° (CI 3.9-8.9; 95%); in the overlying segment before prosthetics—6.1° ± 1.1° (CI 4.4-7.8; 95%), after—3.3° ± .8° (CI 2-4.5; 95%); in the underlying segment to—2.4° ± .5° (CI 1.5-3.2; 95%), after—2.3° ± .6° (di 1.2-3.3; 95%). Using Wilcoxon's T-test, the ROM values of the operated segments (Z = 2.6; P = .007), the ROM values of the overlying segments (Z = 2.7; P = .006) and the underlying segments (Z = .9; P = .3) before and after arthroplasty were determined. Using Spearman correlation, a relation was found between the ROM of the operated and the underlying segment after the intervention (r = .72; P < .05). Conclusion: The experience of using the first Russian endoprosthesis showed the ease of implant placement and a sufficient increase in the range of motion of the operated segment in the early postoperative period in comparison with analogues.

407

P003: Long Term Results of a Dynamic Disc Implant in the Treatment of Degenerative Disc Diseases of the Cervical Spine

Senol Jadik ¹

¹ WARA Hospital, Neurosurgery Department, Kuwait City, Kuwait

Introduction: An alternative to ACDF is the use of dynamic implants. How long they remain mobile and whether they can reduce accelerated degeneration in adjacent segment remains open. Materials and Methods: The files and the radiological data of patients who received a dynamic implant in 2008 and 2009 were evaluated retrospectively. Results: 51 patients (28 female and 23 male) were treated with a dynamic implant. 9 of them were provided bisegmental and 9 with additional ACDF as a hybrid surgery. Mean age was 53.7 (± 11.6). 35 patients were followed up at 5 and 6 years. Results: All were fused during this period. 14 of them had a MacAfee heteretopic ossification grade 3 with nonunion and minimally obtained motion and 21 McAfee grade 4. 6 patients showed radiological ALD (adjacent level disease) with osteophytes and only one of them clinically significant. The NDI was 18% (± 15.1%). Complications: 8 × dysphagia, 3 × hoarseness, 1 × recurrent nerve lesion and 1 × laryngitis, 1 × revision with dorsal foraminotomy. Conclusion: The use of a dynamic implant is comparable to the ACDF in long term follow ups. After 5 years, they are all fused by heteretopic ossification. The advantage is the moderately better outcome in the NDI.

762

P004: Primary Hybrid Cervical Disc Arthroplasty and Fusion Constructs: Reoperation Rates and Outcomes at 8 Year Follow Up

Michael Reiter ¹ , Dan Riew ² , Deeptee Jain ¹ , Amir Kucharski ¹ , Colleen Peters ¹ , Lukas Zebala ¹ , and Michael Kelly ¹

¹ Washington University School of Medicine, St. Louis, USA

² Columbia University Medical Center, New York, USA

Introduction: Cervical disc arthroplasty (CDA) is approved as an alternative to anterior cervical discectomy and fusion for one and two-level degenerative cervical disc disease. Hybrid constructs with ACDF and CDA at contiguous levels are proposed to preserve motion and reduce pseudarthrosis. The purpose of this study was to evaluate long term outcomes and revision surgery rates in patients who underwent hybrid CDA/ACDF. Materials and Methods: A single-surgeon, retrospective cohort was analyzed from 2008 to 2015. Inclusion criteria were: ≥2-level hybrid constructs with CDA and anterior fusion at contiguous levels. Demographic and operative data were collected via chart review and questionnaire. Primary outcome measures were the Neck Disability Index (NDI) and subsequent cervical surgeries. NDI changes were compared with Wilcoxon signed rank test and incidence density rate of second surgeries calculated. Results: 71 patients underwent hybrid CDA/ACDF. 36 completed long-term follow up questionnaire (Mean age 50.2, Mean BMI 31.5, 56% male). Mean follow up was 8.1 years (range, 5.4-11.5 years) with 2-level (23, 64%), 3-level (11, 31%), and ≥4-level (2, 6%) constructs performed for radiculopathy (92%) and myelopathy (8%). 4/36 (11.1%) patients had a second cervical spine surgery (incidence density rate 1.3%). Only 1 underwent revision at the CDA level and 3 patients had adjacent segment surgeries. The mean NDI improved from 41 ± 17 pre-operatively to 24 ± 17 at most recent follow up (TE: 17, P = .0002). 35 Patients were lost to long-term followup. Neither demographic data nor outcomes data were substantially different from study patients. 4 Patients lost to follow-up underwent known second cervical surgeries. Conclusions: Hybrid cervical arthroplasty and fusion constructs have significant improvement of NDI scores and low revision surgery rates at an average of 8 years follow up.

965

P005: Association Between Anterior Bone Loss and Anterior Heterotopic Ossification in Hybrid Surgery

Junbo He ¹ , Beiyu Wang ¹ , Hao Liu ¹ , and Tingkui Wu ¹

¹ West China Hospital, Sichuan University, Orthopedics, Chengdu, China

Introduction: The mechanism of postoperative bone formation still remains unknown. It is considered a risk factor in CDA but is essential for a solid union in ACDF. With HS, we could directly study the mechanism and relationship of different forms of postoperative bone formation. Material and Methods: Ninety-seven patients undergoing contiguous 2-level HS were retrospectively reviewed. The clinical and radiographical outcomes were collected preoperatively and at routine postoperative intervals of 1 week, 3 months, 6 months, 12 months, and at the last follow-up. The initial and postoperative radiographs were compared to determine the incidence of ABL and AHO. Results: The overall incidence rate of ABL was 44.3% (43/97). It was identified in 70.6% of AHO cases (33.3% mild, 41.7% moderate, 25.0% severe) and 38.8% of non-AHO cases (38.7% mild, 45.2% moderate, 16.1% severe). A significant association between ABL and AHO occurrence was found (P = .016). There was no significant difference in prosthesis–endplate depth ratio or disc space angle change between the AHO group and non-AHO group (P > .05). Compared with data preoperatively, clinical outcome scores significantly improved after surgery in both the AHO and non-AHO groups, with no significant differences between the two groups (P > .05). Conclusion: ABL was common in HS, and it related to AHO. The formation of AHO could be an integral part of postoperative bone remodeling, as well as ABL.

1016

P006: Does Fusion Affect the Anterior Bone Loss of Adjacent Cervical Disc Arthroplasty in Contiguous 2-Level Hybrid Surgery?

Junbo He ¹ , Tingkui Wu ¹ , Chen Ding ¹ , Beiyu Wang ¹ , and Hao Liu ¹

¹ West China Hospital, Sichuan University, Orthopedics, Chengdu, China

Introduction: Hybrid surgery (HS) has become an alternative procedure for the treatment of multilevel cervical degenerative disc disease with satisfactory outcomes. However, some adverse outcomes have recently emerged, such as anterior bone loss (ABL). ABL was defined as non-progressive early peri-prosthetic vertebral bone loss commencing within 6 months after surgery at the arthroplasty level. Until now, however, no previous reports have specifically discussed the occurrence of ABL in HS. The primary aim of the present study was to investigate whether the ABL in contiguous 2-level HS was affected by adjacent fusion in vivo compared with CDA alone. Material and Methods: A total of 180 patients undergoing either a 1-level CDA or contiguous 2-level HS were retrospectively reviewed. The clinical and radiographical outcomes were collected preoperatively and at routine postoperative intervals of 1 week, 3, 6, and 12 months and at the last follow-up. The initial and postoperative radiographs were compared to determine the incidence and degree of ABL. Results: ABL was identified in 68.7% of CDA cases (37.9% mild, 34.8% moderate, 27.3% severe) and 44.0% of HS cases (54.1% mild, 27.0% moderate, 18.9% severe). Sex, age, bone mineral density, operation time, blood loss, postoperative alignment, and range of movement at the arthroplasty segment were not related to the incidence of ABL. According to the logistic regression analysis results, ABL showed a significant correlation with the surgery type and body mass index. However, there was no significant difference in the incidence and degree of ABL with or without an adjacent fusion level. Compared with preoperative values, clinical outcome scores significantly improved after surgery in both the HS and CDA groups. No definite clinical effect associated with ABL was found. Conclusion: ABL was common in both CDA and HS. Despite that HS had a lower incidence rate and degree than CDA, the fusion location in HS did not affect the ABL of adjacent CDA.

1023

P007: Association of Cervical Sagittal Alignment with Adjacent Segment Degeneration and Heterotopic Ossification Following Cervical Disc Replacement

Xiaofei Wang ¹ , Han Wang ¹ , and Hao Liu ¹

¹ West China Hospital, Sichuan University, Department of Orthopaedic Surgery, Chengdu, China

Introduction: Cervical sagittal balance plays important roles in transmitting the load of the head and maintaining global spinal balance. This study aimed to identify the association of cervical sagittal alignment with adjacent segment degeneration (ASD) and heterotopic ossification (HO) after Prestige-LP cervical disc replacement (CDR). Material and Methods: We enrolled 132 patients who underwent one-level Prestige-LP CDR with 2-10 years of follow-up. Cervical sagittal alignment parameters, including the degree of C2-7 lordosis (CL), functional spinal unit angle (FSUA), sagittal vertical axis (SVA), and T1 slope (T1s), were measured. ASD and HO were evaluated at the last follow-up. Unpaired t tests and logistic regression analysis were used to identify the associations of cervical sagittal alignment with ASD and HO. Results: We found that patients who developed ASD showed significantly lower FSUA (2.1° vs −1.4°, P < .001) and T1s values (28.4° vs 25.5°, P = .029) after surgery. Similarly, the postoperative CL was significantly better in patients without ASD or HO (18.0° vs 14.4°, P = .043). The decrease in the T1s at the last follow-up was significantly larger in the patients with ASD (−11.0° vs −3.2°, P = .003), HO (−6.7° vs −2.7°, P = .050), and ASD or HO (−7.0° vs −.8°, P < .001) than in those without ASD or HO. Multivariate logistic regression analysis showed that both the FSUA and T1s are associated with ASD and that the degree of CL is associated with postoperative complications. Conclusion: The results imply that maintaining cervical sagittal alignment after Prestige-LP CDR is important.

1030

P008: Correlation Analysis Between Early Fusion Effect and Heterotopic Ossification in Anterior Cervical Hybrid Surgery

Han Wang ¹ and Hao Liu ¹

¹ West China Hospital, Sichuan University, Department of Orthopaedic Surgery, Chengdu, China

Introduction: Hybrid surgery, which involves the combination of ACDF and TDR, has been increasingly used for patients with multilevel cervical degenerative disc disease. The novel technique could tailor the most appropriate surgical procedure to each level according to the degree of degeneration. And in theory, hybrid surgery could maintain range of motion and achieve solid fusion for the meanwhile. Heterotopic ossification (HO) is a common complication of TDR, which also had similar impact on hybrid surgery. As a process of bone formation, HO is similar to fusion process after ACDF. Questions have been raised, in hybrid surgery involving ACDF and TDR, is there a relationship between HO and postoperative fusion effect? Is HO more likely to occur in patients with good fusion effect? To the best of our knowledge, the related studies were still limited and it was the first study that focused on the relationship between HO and fusion. The aim of the present study was to explore the correlation between bone mass of arthrodesis levels and the incidence of HO in anterior cervical hybrid surgery. Material and Methods: Overall, 140 patients with double- or three-level hybrid surgery involving ACDF and TDR were retrospectively analyzed. The height of new born bone tissue at the posterior border of the cage at 3-month follow-up was measured as the early fusion effect. HO was assessed based on McAfee classification system. Additionally, the patients’ basic characteristics, clinical outcomes and range of motion of the replacement levels, superior adjacent levels, and the cervical spine were also evaluated. Results: There were 42 men and 98 women involved with a mean age of 49.86 ± 7.45 years. HO was observed in 102 (72.86%) patients while high-grade HO only in 10 (7.14%) patients. Among all the variables, sex (M:F, 4:34 without HO and 38:64 with HO, P = .002) and height of bone tissue (HO- 2.51 mm vs HO+ 3.52 mm, P = .009) were considered statistically significant between patients with and without HO. And the multivariate logistic regression analysis revealed that the height of new born bone tissue was the only risk factor for HO (OR = 1.914, 95%CI = 1.082-3.387, P = .026). The ROC curve showed an area under curve of .69 and the cut off value was 3.71 mm. And significant differences were observed in the incidence of HO between patients with more than 3.71 mm and less than 3.71 mm. However, no statistical differences were observed in high-grade HO, range of motion of replacement levels, adjacent levels, and the cervical spine between two groups. Conclusion: The height of new born bone tissue between the endplates showed an obvious predictive effect on the occurrence of heterotopic ossification in cervical HS. Patients with more than 3.71 mm new born bone tissue had a higher incidence of HO. However, no significant differences were observed in ROM between patients with and without HO, and the presence of HO did not affect the clinical outcomes, but long-term follow-up was necessary for further study.

1051

P009: Cervical Disc Arthroplasty Combined with Two-Level ACDF for the Treatment of Contiguous Three-Level Cervical Degenerative Disc Disease: A Comparative Study of Different Constructs

Kangkang Huang ¹ , Hao Liu ¹ , Beiyu Wang ¹ , Tingkui Wu ¹ , Yang Meng ¹ , Chen Ding ¹ , Junbo He ¹ , and Ying Hong ²

¹ West China Hospital, Sichuan University, Orthopedics, Chengdu, China

² West China Hospital, Sichuan University, Operation Room, Chengdu, China

Introduction: According to the different numbers and locations of CDAs and ACDFs, three-level hybrid surgery (HS) has many constructs. The primary aim of the present study was to compare the in vivo differences among different hybrid constructs with one-level CDA and two-level ACDF. Material and Methods: A retrospective study was conducted involving patients with contiguous three-level CDDD who underwent one-level CDA and two-level ACDF in our hospital between June 2012 and May 2019. According to the different locations of CDA and ACDF, we divided the constructs into three types: type Ia: CDA was performed at the superior lesion segment, and ACDF was performed at the intermediate and inferior lesion segments; type Ib: CDA was performed at the intermediate lesion segment, and ACDF was performed at the superior and inferior lesion segments; type Ic: CDA was performed at the inferior lesion segment, and ACDF was performed at the superior and intermediate lesion segments. The differences of clinical and radiological outcomes among groups were evaluated. The data were collected preoperatively and at 3 days, 3, 6, and 12 months postoperatively and at the final follow-up. Results: 47 patients were included in the study with 27 patients in the type Ia group, 8 patients in the type Ib group, and 12 patients in the type Ic group. After surgery, all three groups showed significant increase in JOA scores (P < .001) and significant decrease in NDI and VAS scores (P < .001). However, no significant differences in JOA and VAS scores were found among the three groups at any follow-up point. The NDI of the type Ia group at 6 months postoperatively was significantly higher than that of the type Ic group (P < .05). The cervical lordosis was significantly improved after surgery (P < .05). But no significant differences were observed at the final follow-up. The ROMs of the total cervical spine and FSU in type Ic group decreased significantly compared with those in the type Ia and type Ib groups at several follow-up points (P < .05). No significant differences of the ROM of the arthroplasty segment were observed among three groups at each follow-up point. All three groups showed a significant increase of the ROM of superior adjacent segment at the final follow-up compared with preoperative value. The data of the type Ia group was significantly higher at the final follow-up than that in the type Ib group (P < .05). The fusion rates were without significant differences among three groups at any follow-up point. But the fusion rates of the superior ACDF subgroup were significantly higher at 6 and 12 months postoperatively than those of the inferior ACDF subgroup (P < .05). Conclusion: There were no significant differences in the clinical outcomes among constructs concerning different locations of CDA and ACDF in three-level HS. The ROM of the cervical spine in the type Ic group decreased significantly compared with that in the type Ia and type Ib groups. The fusion rate of superior ACDF segments was higher at early timepoints after surgery than that of inferior ACDF segments.

1063

P010: Is Gender a Factor Affecting Long-Term Mobility Failure in Cervical Prostheses?

Alessandro Versace ¹ , Daniele Bongetta ¹ , Elena Virginia Colombo ¹ , Miriam Bua ² , Tommaso Calloni ³ , Marilou Cavaliere ³ , and Roberto Assietti ¹

¹ ASST Fatebenefratelli Sacco, Milan, Italy

² Università degli Studi di Milano, Milan, Italy

³ Università di Milano Bicocca, Milan, Italy

Background: Cervical disc diseases have been treated either by means of anterior cervical discectomy and fusion or by disc replacement with the use of prostheses, whose aim is to maintain motion at the operative level. Sadly, some patients will experience a mobility failure in their cervical prostheses, mainly because of heterotopic ossification. Although some studies are emerging on the long-term incidence of mobility failure, no study has been focusing so far on gender differences in this regard. Aim of the study is to investigate the role of gender in long-term outcome after cervical disc replacement with the use of prosthesis. Methods: We reviewed the charts of 92 patients in a single Institution who underwent single-level cervical disc replacement with a Bryan prosthesis during the period from May 2007 to January 2017. Neck disability index (NDI) and spine-range of motion (S-ROM) scales were employed for subjective evaluation of disability and motion, respectively. Postoperative dynamic radiographic images were employed to evaluate the mobility whereas heterotopic ossification was graded by using the McAfee classification. We also performed a narrative review about gender differences in both structural and biomechanical features of the cervical spine.Results: Study patients (36M, 56F) had a mean age of 40.3 ± 6.8 years and an average follow-up period of 10 ± 3 years. No significant differences were reported between gender groups for both age, level of disc treated and length of stay. NDI scores showed no differences at any follow-up point whereas S-ROM grading was significantly better for females. The incidence of postoperative mobility failure with or without bone formation was relatively high with a significant higher risk in male patients.Women’s cervical spine showed several differences when compared to men’s especially in the following aspects: bone structure (less trabecular density, smaller articular surface, less axial loading, different facet geometry), muscular action (smaller muscular volume for given axial load, different response to loading by muscular groups, lower center of gravity of the muscular response), soft-tissue response (estrogen-related higher tendon laxity and mobility, lower repairing response to trauma), genetic and epigenetic response to osteoarthritis.Conclusion: Among the patients followed up for a mean of 10 years after cervical disc replacement with a Bryan prosthesis, the incidence of mobility failure was significantly higher in males both at S-ROM and radiographic evaluations. Several factors both in static and dynamic features of female cervical spine may play a significant role. Further studies are needed to identify gender-specific responses to both pathology and surgical interventions on cervical spine.

1527

P011: Anterior Single Odontoid Screw Placement for Type Ii Odontoid Process Fractures: A Review of Surgical Technique with a Single Screw in a Case Report

Maria Camila Molina Borda ¹ , Luis Estuardo Jara Silvestre ^1,2

¹ Clinica Universidad de La Sabana, Investigacion, Chía, Colombia

² Clinica Universidad de La Sabana, Neurocirugia, Chía, Colombia

Introduction: Fractures of the odontoid process represent approximately 15% of cervical fractures and about 1-2% of all spinal fractures, having the elder adults a greater probability of suffering this pathology. The treatment of type II odontoid fractures has been the subject of debate for some time due to the management and several options on the surgical approach. Objective: To present a case of type II odontoid process fracture, in which a surgical technique was performed using an anterior approach. Clinical Case: A 78-year-old patient presented mild head trauma and hyperextension cervical trauma after falling from her own height. On examination without neurological deficit, was immobilized with a Philadelphia collar. Simple cervical tomography shows unstable transverse fracture of the base of the odontoid process with retrolisthesis of a 6 mm fragment, Anderson D 'Alonso classification type II with C1-C2 dislocation. Reduction and fixation of the odontoid process was performed through an anterior approach with a single 35 mm × 33 mm screw without complications. Postoperative cervical spine tomography showed a fracture reduction in its entirety. Conclusions: Anterior osteosynthesis with a transnodontoid screw and Mayfield clamp is the surgical technique chosen for recent fractures of the odontoid process, demonstrating optimal fixation rates with preservation of the cervical anatomy and with a lower risk of adjacent morbidity.

1576

P012: Proper Patient Selection and Minimizing Complications in 3- and 4- Level Anterior Cervical Discectomy and Fusion- A Single Center Experience

Ayesha Arshad ¹ , Khandkar Kawsar ¹ , Sondos Eladawi ¹ , and Antonino Russo ¹

¹ Queen Elizabeth Hospital, Neurosurgery, Birmingham, United Kingdom

Introduction: Multi-level Anterior Cervical Discectomy and Fusion (ACDF), though technically challenging, is an accepted treatment for multi-level degenerative cervical spine disease. Although one or two level cervical discectomy is a long known procedure, multi-level discectomies are being done with good success in recent times. But little data is available on avoidance of complications in these. We tried to determine if we can minimize the common complications with proper patient selection and surgical techniques. Methods and Materials: Objectives: 1. To determine the factors for proper selection of the patients, for 3 or 4 level ACDF. 2. To outline the appropriate surgical procedure to avoid the common complications. Design: retrospective study. Method: All patients undergoing 3- and 4- level ACDF for cervical degenerative disease at Neurosurgery department, Queen Elizabeth Hospital Birmingham, UK, over a 5 year-period (15th June, 2014 to 14th June, 2019) were included in the study, after approval by the Central Audit and Research Management System (CARMS) at the hospital. Data Collection: A questionnaire was used to collect data from hospital patient records. All patients were operated by the senior author and followed up in clinics. Results: A total of 32 patients were included in the study. 71.9 % were male and 28.1% were female. The mean age was 50.62 years. (range: 28-72 years). The main indication for surgery was cervical spine spondylotic myelopathy (81.25%), 12.5% had stenosis and 6.25% had retrolisthesis with degenerative disease. 16 patients had 4-level ACDF and 16 patients had 3-level ACDF. 31 patients had only anterior fixation, 1 patient had posterior fixation as well. 68.75% were discharged within 48 hrs, 12.5% left within 72 hours of surgery and only 18.75% stayed longer (6-15 days), mostly for rehab and social packages. The patients were followed up in clinic after discharge. 2 patients were lost to follow up. The mean follow up period for rest of the 30 patients was 33.5 months, (range: 3-54 months). 87.5% patients had improvement in pain on follow up as compared to pre-op, 12.5% had the same pain as pre-op, and it did not get worse in any of the patients. 87.5% patients had improvement in neurology on follow up as compared to pre-op, 9.375% had the same neurology as pre-op, one (3.125%) patient worsened neurologically and developed a C5 radiculopathy. Adjacent level disease was seen in only one patient (3.125%) on follow up. In one case (3.125%), there was development of kyphotic deformity with implant failure. There was no incidence of wound infection, dysphagia, oesophageal or tracheal injury, post-op hematoma, dysphonia or RLN injury. The details of the patient selection process, the surgical method and comparison with available literature will be described during presentation. Conclusions: This study demonstrates that 3- or 4- level ACDF is an effective and safe surgical option in multi-level cervical degenerative disease, provided proper patient selection and good surgical techniques are practised.

1656

P013: Comparison of Kinematic Measures Following Cervical Arthroplasty, Arthrodesis, and Hybrid Procedures

Simon Luong ^1,2 , William Parr ^1,2,3 , William Walsh ¹ , and Ralph Mobbs ^1,2

¹ Surgical and Orthopaedic Research Laboratories, UNSW, Sydney, Australia, Sydney, Australia

² NeuroSpine Surgery Research Group, Prince of Wales Private Hospital, Sydney, Australia, Sydney, Australia

³ 3DMorphic, Sydney, Australia

Introduction: Cervical total disc replacements (TDR) are motion sparing and generally accepted in the clinical literature to reduce adjacent segment disease (ASD) compared to anterior cervical discectomy and fusion (ACDF). A single in-vitro study that found an increase in range of motion (ROM) of the adjacent segments is most often cited, and increased ROM suggested as the underlying biomechanical reason ASD occurs. However, in-vitro fusion models cannot represent biological fusion, as fusion requires biology. Previous studies on ACDF and TDR investigated different TDR devices and did not specify the fusion cages used, making it difficult to draw overarching conclusions about the impact of either procedure on the adjacent segment. Recently, hybrid surgeries utilising a combination of ACDF and TDR devices, as opposed to two-level ACDF (2-ACDF), have been used to treat two-level pathologies to attempt to reduce the risk of ASD. There are limited studies on the biomechanical outcomes of hybrid procedures. The aim of this study is to use clinical data to measure the superior adjacent segment (SAS) ROM and location of the centre of rotation (COR) following single-level and multi-level procedures. Material and Methods: 53 patients were treated with Mobi-C TDR and A-Spine Redmond ACDF devices for whom post-operative (mean 4 months) sagittal flexion and extension x-rays were included and divided into TDR, ACDF, 2-ACDF, and hybrid groups. Landmarks were applied to flexion and extension radiographs to define C2-C7 vertebral positions. The landmarks for each vertebra inferior to each interbody space in flexion and extension were superimposed and the ROM and COR of each superior vertebra was calculated. Differences between groups were tested for by ANOVA and variance testing. Results: There were no significant differences in SAS ROM (P = .36) nor in the location of SAS COR between TDR and hybrid groups. Significant differences in SAS COR between fusion groups and motion sparing groups were found, and markedly in the variance of distance from the SAS vertebra to its COR (P < .0001). No differences within fusion groups and motion sparing groups were found. Conclusion: In this short-term follow up there was no significant difference in ROM between motion sparing and fusion procedures at a mean post-operative time point of 4 months, but significantly more variance in the location of the SAS COR following fusion procedures compared to TDR and hybrid procedures. Whilst some fusions had similar COR locations to TDR and hybrid procedures, others had markedly different COR locations. This may explain the clinical incidence of ASD following fusion procedures: where the SAS COR has moved considerably there are differences in the SAS movement patterns that lead to soft-tissue degeneration. SAS ROM and COR in hybrid surgery is similar to TDR, providing a biomechanical rationale for hybrid surgeries. The methods in this study can be applied to future follow-up.

1850

P014: The history and evolution of cervical disc replacements

David Turkov ¹ , Alan Job ¹ , Cesar Iturriaga ¹ , and Rohit Verma ¹

¹ Northwell Health, Department of Orthopaedic Surgery, Manhasset, USA

Introduction: Radiculopathy and myelopathy resulting from degenerative disc disease is commonly treated with anterior cervical discectomy and fusion (ACDF), but there is a high incidence of postoperative pseudoarthrosis and adjacent segment disease. With recent advances in cervical disc arthroplasty (CDA), we performed a review of published articles, examining the latest clinical data on the efficacy, safety, and complications of the current cervical disc devices on the market. We focused on the long-term follow up data for single-level, multi-level, and hybrid CDA when compared to ACDF. We examine the historical progression and evolution of CDA with an emphasis on the clinical improvements achieved with each new implant. Material and Methods: A search was performed utilizing PubMed, Google Scholar, and Clinical Key to identify articles on one-level, two-level, and hybrid approaches to CDA. The articles were reviewed by two authors for relevance and power with higher emphasis placed on FDA IDE trials. Results: The results conclude that CDA has an equivalent or improved clinical outcome when compared with ACDF with improved patient reported neck disability indexes and VAS neck pain scale. The most recent implantable discs also have lower rates of dysphagia, adjacent segment disease, pseudoarthrosis, and reoperation, when compared to ACDF. The data suggests there is no increased rate of reoperation in patients treated with multilevel CDA when compared to ACDF. In addition, the data from the limited clinical trials suggests that Hybrid CDA and ACDF is safe and decreases risk of ASD. Conclusion: The current literature suggests CDA is a safe and effective alternative to ACDF with similar or improved clinical outcomes. The postsurgical clinical outcomes have improved significantly with the evolution of cervical discs. However, additional long-term follow up studies may strengthen the evidence. The data supporting the efficacy of the M6-C disc may also be strengthened by performing an additional prospective investigation with a larger population size and by including an ACDF control group to compare the rates of ASD and the long-term clinical outcomes. The data from the limited clinical trials suggests that Hybrid CDA and ACDF is safe and decreases risk of ASD. However, the data is of low quality and more hybrid studies must be performed in the future.

1856

P015: Comparison of Cervical Disc Arthroplasty and Anterior Cervical Discectomy and Fusion: Patients Perspective of Satisfaction and Forgotten Surgery

Jitesh Manghwani ¹ , Abhinandan Reddy Mallepally ¹ , Bibhudendu Mohapatra ¹ , and Kalidutta Das ¹

¹ Indian Spinal Injuries Center, New Delhi, India

Introduction: A retrospective cohort follow up study was done assessing the patient satisfaction undergoing single level anterior cervical spine surgery (cervical disc arthroplasty and anterior cervical discectomy and fusion) for cervical radiculopathy. We aim to determine whether a group of patients is more satisfied than the other group and whether any group had “forgotten surgery”. Material and Methods: Data was analyzed retrospectively from 126 patients who underwent single level anterior cervical arthroplasty or anterior cervical discectomy and fusion in cases with radiculopathy. Analysis of pre operative and post operative scores with a follow up at 2 years was done. The parameters of comparison were improvement in motor scores, sensory scores, dysphagia, neurodeficit, Neck Disability Index (NDI), European Quality of Life 5D (EQ-5D), visual analogue score (VAS), and Short Form-36 Physical Component Summary (SF-36 PCS). Patients underwent a questionnaire to confirm the awareness of neck surgery at the end of 2 years. Results: On follow up all the patients had significant decrease in the pain scores with improvement in Neck Disability Index (NDI), European Quality of Life 5D (EQ-5D), visual analogue score (VAS), and Short Form-36 Physical Component Summary (SF-36 PCS) scores in both the groups. However apart from NDI scores there was no statistical significant difference in the two groups. Mean NDI scores were lower in the arthroplasty group and the difference was statistically significant. Change in profession wasn’t statistically significant. No statistical significance was found in the incidence of adverse events. Higher rates of dissatisfaction were found in patients with underlying psychological comorbidities. Statistically significant difference between the two groups with respect to “forgotten surgery” was found at the end of 2 years, with higher patients forgetting surgery in arthroplasty group. Conclusion: Patients undergoing anterior cervical surgery have gratifying surgical satisfaction. The satisfaction rates with discectomy and fusion are similar to cervical disc arthroplasty. However, patients undergoing arthroplasty have lower NDI scores with the higher chances of “forgetting surgery” as compared to discectomy and fusion.

Arthroplasty-Lumbar

1461

P016: Vertebral Fractures After Lumbar Total Disc Replacement, Is There Any Need for Classification System? Systematic Review of Literature

Ali Al-Hilli ¹ and Michael Janssen ²

¹ College of Medicine University of Baghdad, Baghdad, Iraq

² Centre for Spine and Orthopedics, Denver, CO, USA, Denver, USA

Purpose: Disc replacement is an option to treat symptomatic lumbar degenerative disc disease (DDD). New techniques and implant designs have evolved to improve the outcome. Little literature has been published about osseous complications associated with lumbar total disk replacement (LTDR). Study Design: Systematic review of literature. Methods: PubMed search was conducted, searching for bony complications after LTDR. There are 929 articles regarding LTDR. 330 articles discussing complications, with a more intensive search for bony complications following LTDR, fourteen articles were found, mainly as case reports, published between 1997 and 2013. The relation between bony complications, site of fractures and type of prosthesis, technique, possible cause and time of presentation were studied. Results: A total of 88 bony complications were identified from the search, including 60 cases of subsidence, 7 cases vertebral body split fractures (VB-SF), 3 pedicle fractures, 9 end plate fractures, spondylolysis and pars fractures in 4 cases and facet fractures in 5. The main causes are technical and implant design. To date, there is no classification system available considering Periprosthetic fractures after LTDR. Conclusions: Bony complications after LTDR are reported. Proper implant, patient selection and technique can reduce the morbidity. There is need for a classification system addressing Periprosthetic fractures after LTDR, it is crucial to guide the diagnosis and treatment.

Keywords

lumbar total disc replacement, bone complications, classification

1871

P017: A Novel Lumbar Total Joint Replacement as an Alternative to Fusion for Degenerative Lumbar Conditions: A Comparative Analysis of Patient-Reported Outcomes at One Year

Alex Sielatycki ¹ , Clinton Devin ² , Jacquelyn Pennings ³ , Craig Humphreys ⁴ , Scott Hodges ¹

¹ Center for Sports Medicine and Orthopadics, Spine Surgery, Chattanooga, USA

² Steamboat Spine Center, Steamboat Springs, USA

³ Vanderbilt University Medical Center, Nashville, USA

⁴ Kenai Spine, Soldotna, USA

Introduction: Effective alternatives to lumbar fusion for degenerative conditions have remained elusive. While fusion may be effective with proper indications, it also commonly results in adjacent level disease, reoperation, sub-optimal outcomes, and high costs. Anterior total disc replacement does not address facet pathology or central/recess stenosis; resulting in limited indications. There is a need for a posterior-based motion-preserving option that allows for neural decompression, facetectomy, and reconstruction of the disc and facets. Materials and Methods: Study Design/Setting: A retrospective analysis of prospective data comparing outcomes for lumbar total joint replacement (LTJR) patients to transforaminal lumbar interbody fusion (TLIF) patients at an academic teaching hospital. Patient Sample: Analysis was conducted on 148 adult TLIF patients who were propensity matched to the 52 LTJR patients for a total sample of 200. Outcome Measures: Self-reported Oswestry Disability Index (ODI) and Numeric Rating Scale (NRS) for back and leg pain were compared preoperatively, 3 months and 1 year after surgery. Methods: The implant is a motion-preserving lumbar reconstruction that replaces the function of both the disc and facets and is implanted using a bilateral trans-foraminal approach with complete facetectomies. Adult patients with degenerative lumbar pathology undergoing either LTJR or open TLIF were analyzed. Trauma, tumor, and infection cases were excluded. Propensity score matching was performed to ensure parity between the cohorts. Multivariable regression analyses were done to compare the one-year results as measured by three different standards to assess procedure success. Results: At 3 months, both the LTJR and TLIF cohorts showed significant and similar improvements in ODI and NRS back and leg pain. At one year, the LTJR cohort showed continued improvement in ODI, NRS back pain, and NRS leg pain, while the TLIF group showed a plateau for ODI and a worsening trend in back and leg pain. In a series of three multivariable logistic regressions, LTJR was shown to provide 4.0 times greater odds of achieving the minimal clinical symptom state in disability and pain (ODI < 20%, NRS back and leg pain < 2) and 3.6 and 2.6 times greater odds of achieving minimal clinically important difference (MCID) (30% reduction in ODI) and substantial clinical benefit (18% reduction in ODI) as compared to TLIF. Conclusions: Here we present a comparative analysis for the first 52 patients undergoing a novel, posterior-based LTJR for the lumbar spine versus TLIF for degenerative pathology. The approach for the LTJR allows for wide neural decompression, facetectomy, and complete discectomy, with the implant working to replace the function of the disc and facets to preserve motion. At one year, the LTJR cohort showed significant improvement in ODI and NRS back and leg pain leg pain as compared to TLIF. These results suggest that wide neural decompression combined with motion preservation using this novel LTJR may represent a potential improvement over TLIF for treating certain degenerative conditions. Longer term follow-up is underway to evaluate the durability of this procedure and its impact on adjacent segments.

Basic Science

232

P018: Annular Disc Fissures: Study and Treatment

Carlos Mariano Nirino ¹ and Carlos Nemirovsky ²

¹ Hospital Santamarina, Orthopedics and Traumatology, Monte Grande, Argentina

² Corporacion Medica, Buenos Aires, Argentina

Introduction: Annular disc fissures constitute disc pathology with its own entity and independent of the rest of the disc pathologies including but not excluding disc protrusions. This is a study made on patients in our office in the department of Orthopedics and Traumatology in Santamarina Hospital of Monte Grande in Buenos Aires, Argentina by the institution's column team. Annular fissures can be classified according to their location in central, lateral and intrafunicular; according to its relationship with other disc diseases in annular fissures without protrusions; with mild protrusions (less than 2 mm), with moderate protrusions (less than 5 mm) and with severe protrusions (more than 5 mm and that include at least 50% of the posterior surface of the disc); according to its distance to the posterior surface of the annulus in millimeters and finally in closed and open annular fissures, the last ones when the nucleus pulpous is in contact with the contents of the spinal canal. We perform three different types of treatments; orthopedic medical treatment, selective nerve root blocks and surgical treatment. In this last case we use two different techniques; simple distraction of the affected disc or disectomy plus transient fixation. We studied 62 patients with good results in 80% of the cases with clinical treatment, 10% with persistent pains and requirement of root block and the remaining 10% required surgical treatment. Materials and Methods: 62 patients were evaluated in the office with annular fissures. Only patients younger than 60 years old were considered in this study. All of them were studied by Rx and MRI and treated by the same column team. Patients older than 60 years and those who had previously undergone surgery or had a selective nerve root block were excluded from the present study. Surgical technique: The technique consists of performing the transligamentary microdiscectomy plus the transitory fixation with polyaxial transpedicular screws and bars with the distraction of the system. In case that the transligamentary microdiscectomy is not performed, it is only fixed with polyaxial transpedicular screws and bars and the distraction of the system is performed. In none of the cases arthrodesis is performed. Results: In general, patients resolved their symptoms with the primary indication, the orthopedic medical treatment, in a period from 60 to 90 days. In a small percentage, they underwent a selective nerve root block, which was followed up periodically for 30 days and only a minimal percentage did not evolve favorably and required surgery. None of the operated patients presented recurrences or needed reoperation. We have controls of more than 6 years. We only considered surgical treatment when the previous treatments failed. Conclusions: After an exhaustive study, we consider that it is necessary to treat annular fissures as a pathological entity different from a herniated disc. To be able to investigate it in the office and classify them according to their location and characteristics will give a singular symptomatology and will guide us in the choice of the appropriate treatment.

254

P019: Co-morbidities, Which Influence the Decision for 360 Degrees Stabilization of the Spine

Orlin Pavlov ¹ , Nikolay Mirchev ¹ , Alexa Ruiz ¹ , and Robert Behr ¹

¹ Klinikum Fulda, Department of Neurosurgery, Fulda, Germany

Introduction: The indications for 360 degrees stabilisation of the spine depend on many factors, including the underlying pathology, location of the pathology, Karnofski index of the patient, patient related factors such as age, sex and the co-morbidities. Some of these factors are going to be against and some of them for a 360 degrees stabilisation of the spine. Methods: In our study, we focus on the co-morbidities, which have crucial influence on the bone density, mobilisation of the patient and biomechanics on the muscles of the spine. This is a single center, multi-surgeon retrospective analysis of all patients, who underwent a 360 degrees stabilisation. 25 patients, mean age 69.8 (range 42-85), operated between 2013 and 2018, who underwent a 360 degrees fixation of the spine (cervical, thoracic and lumbar), whereas the ventral stabilization was performed through vertebral body replacement procedure of the spine in the period of 2014 to 2018 were enrolled in the study. Results: The revision surgeries were higher in the group with the co-morbidities. As a total of 5 patients underwent revision surgeries (all ventral)- 4 of the patients had a co-morbidity (1 patient with hysterectomy, 1 osteoporosis, 2 m. Bechterew) and only one had no co-morbidities. That makes 80% of the patients, who underwent a revision surgery had a co-morbidity, which influenced the bone density. Both patients, who had m. Bechterew had to undergo a revision surgery and precisely a 360 degrees stabilisation of the spine. Conclusion: The proper surgical planning, regarding the co-morbidities, increases the number of indications for 360 degrees stabilisation of the spine, so further surgeries on one patient could be prevented.

262

P020: Crosstalk Between Autophagy and Apoptosis in Intervertebral Disc Degeneration: A Review of Pathways and Mechanisms

Bruno Saciloto ¹ , Asdrubal Falavigna ¹ , Charles Carazzo ¹ , Manuela Peletti-Figueiró ¹ , and Natália Fontana Nicoletti ¹

¹ University of Caxias do Sul, Department of Neurosurgery, Caxias do Sul, Brazil

Introduction: The degenerative disc disease (DDD) physiopathology remains unclear. The autophagy process, an evolutive and physiological process, has been closely associated with aging and apoptosis. Recently, clinical and animal studies have recognized that cell death caused by apoptosis and autophagy was involved in DDD. Despite these studies, the influence and relation between these two phenomena in vivo is not completely understood. The objective of this review is to clarify the crosstalk between autophagy and apoptosis and the possible signalling pathways involved in DDD. Material and Methods: A systematic literature review was performed using the PubMed, Web of Science and Scopus databases to select the studies related to the interplay between autophagy and apoptosis in the intervertebral disc (IVD), either in humans or in animals. The PICOT model was applied in order to select adequate studies. All three databases were screened with the same MeSH terms. The research period was established with a final date of November 2018. Three independent researchers conducted the review. Full-text papers were obtained only for those articles which matched criteria for autophagy and apoptosis in conjunction to influence disc degeneration. Results: The search identified 82 records. Fifteen of these articles underwent a full-text analysis and were included in the review (Table I). All studies showed some relation between autophagy and apoptosis in DDD, and the crosstalk between autophagy and apoptosis was described in 8 studies.

Table I. Autophagy and apoptosis crosstalk studies.

Abbreviations: NP = nucleus pulposus. ROS = reactive oxygen species. DDD = degenerative disc disease.

Conclusion: Based on the current data, autophagy had a crucial role in DDD and might be associated with the protection against apoptosis

263

P021: Crosstalk Between Autophagy and Apoptosis in in Intervertebral Disc Degeneration

Bruno Saciloto ¹ , Asdrubal Falavigna ¹ , Charles Carazzo ¹ , Manuela Peletti-Figueiró ¹ , and Natália Fontana Nicoletti ¹

¹ University of Caxias do Sul, Department of Neurosurgery, Caxias do Sul, Brazil

Study Design: Basic-science paper. Objective: To describe the relationship between autophagy and apoptosis and the possible signalling pathways involved in degenerative lumbar intervertebral disc. Summary of Background Data: Autophagy and apoptosis are regulatory cellular mechanisms that determine many pathologies, including degenerative intervertebral disc disease. The interactions between these events in the damage or protection of intervertebral disc cells and in cellular homeostasis remain controversial. Methods: The sample size was twenty patients who underwent lumbar spine surgery for symptomatic disc herniation or spondylolisthesis. Intervertebral discs were classified by magnetic resonance as Pfirrmann grade IV and grade V. Six patients were operated on two levels, resulting in twenty-six intervertebral discs that were submitted to immunohistochemistry to verify the protein expression of autophagy and apoptosis markers. Results: The autophagic markers had greater protein expression in the human intervertebral disc (Pfirrmann Grades IV and V). Under these conditions, autophagy and apoptosis showed a negative correlation. Regarding apoptosis, caspase 8 presented the highest protein expression, which allows inferring the preference for the extrinsic pathway in cell death. Conclusions: Autophagy had the greatest protein expression negative profile compared to apoptosis. Caspase 8 had the highest protein expression in apoptosis.

Level of Evidence: 4.

Keywords

intervertebral disc degeneration, autophagy, apoptosis, crosstalk

290

P022: Morphological Features of the Thoracolumbar Vertebrae and its Clinical Significance in the Treatment of Osteoporotic Vertebral Fracture: Study of the Indian Population

Ghanshyam Kakadiya ¹

¹ Topiwala National Medical College & BYL Nair Hospital, Department of Orthopaedics, Mumbai, India

Introduction: Kyphoplasty is an effective method for the treatment of the osteoporotic vertebral fracture. Kyphoplasty can more effectively restore vertebral height, correct kyphosis. The most common complication of the kyphoplasty is cement leakage (8.0% in our institute). The study aim was to investigate the morphological features of the posterior vertebral wall in Osteoporotic fracture patients. Methods: Total of 196 patients with a thoracolumbar osteoporotic vertebral fracture who were managed with kyphoplasty from 2015 to 2018 retrospectively included in this study. CT-3D reconstruction and multiplanar reconstruction of the thoracolumbar spine was done and the following parameters were measured and analysed (a) AB, the distance between the junctions of the posterior border of the bilateral vertebral body and the medial cortical at the axial plane of vertebral arch; (b) OC, the distance between line AB and point O (the top point of spinal canal intruded into the relative vertebral body); (c) PC, the distance between line AB and the top point of the anterior edge of the body; (d) R = OC/PC was calculated (in the C arm fluoroscopy lateral imaging, the ratio of the lumbar of the vertebral disc to the sagittal diameter of the vertebral body). To compare the OC values of T12 and L1 through independent sample t-test. Results: The range of PC values from T6 to L5 was from 23.42 ± .21 mm to 44.38 ± 4.51 mm, the OC value from T6 to T12 was from 3.83 ± .13 mm to 5.21 ± .06 mm, the data from two groups were gradually increasing. The OC value from T12 to L5 was from 5.21 ± .06 mm to 0 mm, which was gradually decreasing. The R-value from T6 to T12 was close to .16(1/6), compared with the thoracic vertebra, the lumbar vertebra decreased significantly, which was significantly less than 1/6 in L1 to L3, and was close to 0 in L4 and L5. The difference between the OC values of T12 and L1 was statistically significant (P < .05). Conclusions: The posterior wall morphology of thoracic vertebral body is significantly different from that of lumbar vertebra, and the OC structure causes the posterior wall of the middle and lower thoracic vertebral body to be located in the posterior of the vertebral body 1/6. Due to the presence of OC structure in the middle and lower thoracic vertebra, it is possible to reduce the occurrence of bone cement leakage into the spinal canal through avoiding bone cement distribution over the posterior 1/6 of the vertebral body in kyphoplasty.

431

P023: An Anatomic Study Exploring Differences in Pars Interarticularis Distance and Spinal Canal Width Between Lumbar Levels and its Effect on Lumbar Decompression

Innocent Njoku ¹ , Joshua Park ¹ , Amelia Clarke ¹ , and Christina Cheng ¹

¹ University Hospitals Cleveland Medical Center, Orthopaedic Surgery, Cleveland, USA

Introduction: A wide laminectomy to adequately decompress neural elements without compromising the structural integrity of the spinal column is ideal. Over resection of the posterior elements resulting in pars fracture and instability have been reported. The purpose of this study is to assess the differences in pars interarticularis distance (PID) and spinal canal width (SCW) at each level of the lumbar spine and to determine its effect on the extent of laminectomy. We hypothesize that there are significant PID and SCW variations across lumbar levels which will influence laminectomy width at each lumbar level. Material and Methods: We performed an anatomic study measuring PID and SCW in the lumbar spine from 93 skeletally matured osseous specimens from the Hamann-Todd Osteological Collection located at the Cleveland Museum of Natural History. We examined specimens between the ages of 20-30 years at the time of death. PID and SCW at each lumbar level in each specimen were measured with calipers. PID is defined as the narrowest distance between lateral edges of the pars. SCW was measured from the medial wall of one pedicle to the medial wall of the contralateral pedicle. Groups were compared using an independent sample t-test, one-way ANOVA, and Wilcoxon test, and significance was set at P < .05. Results: The average age of death for all specimens was 26 ± 3 years. There was a significant increase in mean PID from L1 to L5 in all specimens (P < .01). Mean PID at L1, L2 and L5 were significantly greater in males compared to females (P < .05) with no difference at L3 and L4. Mean PID at L1 and L2 was significantly greater in AA compared to Caucasian (P < .01) with no difference at L3, L4, and L5. Mean SCW increased from L1 to L5 in all specimens and significant differences were seen between L2-L3 (P = .02), L3-4 (P < .01), and L4-5 (P < .01) with no difference between L1 and L2. Mean SCW was significantly greater in males compared to females at L1, L2 (P < .01), and L3 (P < .05) with no difference at L4 and L5. Mean SCW was significantly greater in AA compared to Caucasians at L1 (P < .01) with no difference at L2, L3, L4, and L5. The ratio of PID to SCW significantly increased from L1 to L5 (P < .01). Ratios at L1 to L3 were less than 1.5 and ratios at L4 and L5 were 1.5 or greater. Conclusion: Our study suggests that the distance between PID and SCW increases from L1 to L5 in AA and Caucasian females and males. However, the respective increase in SCW at each lumbar level is less than the respective increase in PID at the same levels. This suggests that there is a wider window available for decompression without compromising spinal stability in the lower lumbar spine compared to the upper. Care should be taken to preserve the pars while decompressing the upper lumbar spine to avoid postoperative spinal instability.

445

P024: How has Minimum Clinically Important Difference (MCID) Withstood the Test of Time in the Realm of Clinical Spinal Surgery? A Review

Wendy Lee ¹ and Chung Chek Wong ²

¹ Sibu Hospital, Orthopaedic Surgery, Sibu, Sarawak, Malaysia

² Sarawak General Hospital, Orthopaedic Surgery, Kuching, Sarawak, Malaysia

Introduction: In an effort to justify clinical worthiness of spinal surgeries across a multitude of spinal disorders beyond their established statistical significance, Minimum Clinically Important Difference (MCID) has garnered significant limelight since its original conceptualization by Jaeschke et al. Ascertainment of MCID threshold values going by the fundamental anchor-based and/or distribution-based approaches engenders discontentment and continues to undergo relentless refinement through time. We set out to explore the fate of complementary elements that have gotten onboard this platform and the stance of MCID three decades later. Material and Methods: We performed literature search across MEDLINE, EMBASE, VHL Regional Portal database using translatable MESH terms on the utilization and examination of MCID metric in spinal surgery patients. We included literature in English language without imposing any time limit. Shortfalls put forth by studies that fulfilled inclusion criteria were aggregated, analyzed and synthesized to elicit the evolutionary stance of this metric serving as yardstick deemed by patients to be informing true clinical benefits that validate the “decision of treatment”. New approaches proposed to elevate the value of MCID were reviewed of its contextual relevance over time. Results: We explored a total of 29 studies spanning a 13-year period. Across the board, MCID varied considerably over each Patient Reported Outcomes (PROs) domains depending upon the approach(es) used. Remarks thus surfaced on its generic generalizability, or its inevitable tailoring to specific entity for each PROs, notwithstanding the less-than-stringent disease definitions and diagnosis ascribed to the so-formed homogenous patient populations. Intuitively, it bears the floor and ceiling effects as influenced by baseline scores and pre-existing disease severity. Importantly, misconceptions were clarified to re-emphasize the basic premise of MCID being targeted at individualized patient treatment rather than comparison between different treatment arms. Despite validations of PROs, surgeon’s rating on clinical responsiveness, expert panel Delphi consensus and the familiar 30% upscale change were probed to enhance objectivity beyond what is perceived by patient, hailed to be tinted by potential recall bias. “Objectified” anchor, namely—Japanese Orthopaedic Association Back Pain Evaluation Questionnaire (JOABPEQ) is regionalized at best. Timed Up and Go (TUG) objective assessment tool trended transiently. Minimum Detectable Change (MDC), on the other hand, is recurrently revealed and objectified alongside MCID as the statistical marker that negates measurement error, albeit at the expense of the statistical soundness of studies at hand. Adoption of triangulation mechanism is thus proposed, not to have MCID as a standalone entity but taking into account measures to minimize, if not nullify potential error. Conclusion: Although there appears no end in sight to the attainment of a much desired “gold-standard” MCID metric, the literature, however, is credited to its relentless strive in generating MCID while acknowledging its pitfalls along the way. MCID expressed in varied ranges instead of static number may seem far from simplistic. Perhaps, when translated into complex spinal population as such, the current MCID metric stands to provide a realistic spectrum of patient outcomes reference until another concept with even greater global and generic rigor comes along, so to speak.

749

P025: A Novel Bone Graft Outperforms Local Autologous Bone in Stand-Alone Posterolateral Fusion. A Propensity Weight Adjusted Comparison

Scott Daffner ¹ , Joshua Bunch ² , Douglas Burton ² , Alden Milam ³ , Daniel Park ⁴ , Peter Whang ⁵ , John Jones ⁶ , and Howard An ⁷

¹ West Virginia University, Morgantown, USA

² University of Kansas Medical Center, Kansas City, USA

³ OrthoCarolina, Charlotte, USA

⁴ Beaumont Center, El Paso, USA

⁵ Yale, New Haven, USA

⁶ Bioventus, Durham, USA

⁷ Rush Ortho, Chicago, USA

Introduction. The aim of this study was to compare clinical and radiologic outcomes of local autologous bone (LAB) to a novel allograft bone graft substitute (BGS) that retains multiple endogenous growth factors in instrumented posterolateral lumbar fusion (PLF). Methods: The BGS group underwent a single- (n = 26) or two- (n = 16) level procedure and the LAB group all underwent a single-level procedure (n = 121). Using the propensity score weighting approach to adjust for nine likely baseline confounders, 12-month fusion and clinical outcomes were compared. After estimation of propensity scores, all 42 BGS and 82 LAB patients within the BGS support region were included in the analysis. Continuous outcomes were analyzed using a weighted mixed effects models for repeated measures. Results: The fusion rate was 84% and 61% in the BGS and LAB groups, respectively (P = .028, RR = 1.4 (95% C.I. = 1.0–1.9). At 12-month follow-up, both groups showed statistically significant improvements in all clinical outcomes. The improvements in Oswestry Disability Index, back pain, leg pain, and SF36 Physical Component Score were better in the BGS group compared to the LAB group. Discussion and Conclusion: The novel bone graft substitute is a viable replacement for local autologous bone and achieves better radiologic fusion rates and better patient outcomes than LAB in stand-alone PLF.

FDA DEVICE/DRUG STATUS: OSTEOAMP® is compliant to 21 CFR 1271 and is regulated as a 361 HCT/P.

Keywords

allograft, bone graft substitute, local autologous bone, posterolateral lumbar fusion, propensity score analysis

802

P026: Minimally Invasive Swine Spine Surgery Training

Alberto Gotfryd ¹ , Fábio Chaud de Paula ¹ , Marcel Sauma ¹ , Alexandre Iutaka ¹ , Luciano Rodrigues ¹ , Guilherme Meyer ¹ , Marcelo Teivelis ¹ , Arthur Poetscher ¹ , David Del Curto ¹ , Davi Kang ¹ , Luciana Cintra ¹ , Guilherme Gregores ¹ , Mario Lenza ¹ , and Mario Ferretti ¹

¹ Hospital Israelita Albert Einstein, Sao Paulo, Brazil

Introduction: Growing demand for surgical techniques in the last decades has stimulated the emergence of new methods of teaching and training surgeons. Regarding the spine, the emergence of minimally invasive surgeries is highlighted, which, despite having benefits over conventional techniques, are related to longer learning curves. In addition, modern techniques require technological resources that are not always available in traditional education centers. Among simulation types, the one that offers the most realism is the use of live animals. Key advantages include controlling bleeding, managing tissue with consistency similar to real tissue, and encouraging teamwork and division of responsibilities in the operative field. Due to anatomical similarities, swines are used for surgeon training in various medical fields. However, to the authors' knowledge, there is no literature describing training of minimally invasive spine procedures in swine. The authors hypothesize that it is possible to train such surgical techniques in a swine experimental model, obtaining realism similar to that observed in human surgeries. Material and Methods: This is an experimental article. Twenty-two Large White class swine models, weighing between 60 and 80 kg, were the subject of surgical simulations, performed during theoretical-practical courses for training of surgical techniques—microsurgical and endoscopic lumbar decompression, percutaneous pedicular instrumentation, lateral access to the thoracic spine and anterior and retroperitoneal to the lumbar spine and management of complications—by 86 spine surgeons. For each surgical technique, porcine anatomy (similarities and differences in relation to human anatomy), access route and dimensions of the instruments and implants used were evaluated. Thus, the authors describe the feasibility of each operative simulation as well as suggestions for training optimization. Results: The study results are presented in a descriptive manner, with figures and illustrations. Neural decompression surgeries—microsurgeries and endoscopic—and pedicular instrumentation presented higher similarities to human surgeries. On the other hand, intradiscal procedures had limitations due to the narrow discal space in swines. We were able to simulate situations of surgical trauma in surgical complications scenarios, such as liquoric fistulas and excessive bleeding, with comparable realism to human surgeries. Conclusion: A porcine model for simulation of minimally invasive spinal surgical techniques had similarities with human surgeries and is therefore feasible for surgeon training.

826

P027: LncRNA SULT1C2A Regulates Foxo4 in Vitamin A Deficiency Induced Congenital Scoliosis Through PI3K-AKT Pathway

Chong Chen ^1,2 , Guoyan Liang ^1,2 , and Yunbing Chang ^1,2

¹ Guangdong Provincial People's Hospital, Spine Surgery, Guangzhou, China

² Guangdong Academy of Medical Science, Guangzhou, China

Introduction: Congenital scoliosis (CS) is the result of anomalous vertebrae development, but the pathogenesis of CS remains unclear. Long non-coding RNAs (lncRNAs) have been implicated in embryo development, but their role in CS remains unknown. In this study, we investigated the role and mechanisms of a specific lncRNA, SULT1C2A, in somitogenesis in a rat model of vitamin A deficiency (VAD)-induced CS. Material and Methods: The competitive endogenous RNA (ceRNA) mechanism was validated by bioinformatics analysis and a dual luciferase reporter gene assay. SULT1C2A, rno-miR-466c-5p, and Foxo4 expression in embryos was detected by quantitative RT-PCR (qRT-PCR) and northern blot analysis. Western blot analysis was performed to measure PI3K, AKT and phosphorylated AKT expression. Results: Bioinformatics analysis and quantitative real-time PCR (qRT-PCR) indicated that SULT1C2A expression was down-regulated in VAD group, accompanied by increased expression of rno-miR-466c-5p but decreased expression of Foxo4 and somitogenesis-related genes such as Pax1, Nkx3-2 and Sox9 on gestational day (GD) 9. Luciferase reporter and small interfering RNA (siRNA) assays showed that SULT1C2A functioned as a competing endogenous RNA to inhibit rno-miR-466c-5p expression by direct binding, and rno-miR-466c-5p inhibited Foxo4 expression by binding to its 3' untranslated region (UTR). The spatiotemporal expression of SULT1C2A, rno-miR-466c-5p and Foxo4 axis was dynamically altered on GDs 3, 8, 11, 15 and 21 as detected by qRT-PCR and northern blot analyses, with parallel changes in Protein kinase B (AKT) phosphorylation and PI3K expression. Conclusion: Taken together, our findings indicate that SULT1C2A enhanced Foxo4 expression by negatively modulating rno-miR-466c-5p expression via the PI3K-ATK signalling pathway in the rat model of VAD-CS. Thus, SULT1C2A may be a potential target for treating CS.

883

P028: Sensory Innervation of Human Bone: An Immunohistochemical Study to Further Understand Bone Pain

Jasper Steverink ¹ , Douwe Oostinga ¹ , Floris van Tol ¹ , Mattie van Rijen ¹ , Claire Mackaaij ² , Suzanne Verlinde-Schellekens ² , Bas Oosterman ³ , Albert Van Wijck ⁴ , Tom Roeling ² , Jorrit-Jan Verlaan ¹

¹ University Medical Center Utrecht, Orthopedics, Utrecht, The Netherlands

² University Medical Center Utrecht, Anatomy, Utrecht, The Netherlands

³ SentryX B.V., Austerlitz, The Netherlands

⁴ University Medical Center Utrecht, Anesthesiology, Utrecht, The Netherlands

Introduction: Skeletal diseases and their surgical treatment can lead to considerable pain. Spinal surgery ranks amongst the most painful surgical interventions overall. Postoperative pain is correlated with prolonged hospital stay, decreased mobility and delayed rehabilitation. The underlying mechanisms and various etiologies of skeletal pain make this pain difficult to treat adequately. A potential explanation for the severe pain reported is the innervation density of bone. Rodent studies have shown high innervation density in the skeleton and presence of Að- and C-fibers, but literature on human bone innervation is lacking. To better understand skeletal pain, this study aimed to obtain insight in the density and distribution of sensory innervation of the human skeleton using fluorescent immunohistochemistry. Material and Methods: Macro- and microscopically healthy tissue was collected from human bodies through a donation program. Specimens from the spine, skull, upper and lower extremity were collected. Of each bone, a sample of periosteum, cortex and bone marrow was obtained. Samples were decalcified and mounted on histology slides before immunohistochemical staining. Sections were stained using anti-PGP9.5 as an overall neuronal marker, anti-NF200 for Að-fibers and anti-CGRP for C-fibers. Sympathetic fibers were stained with anti-TH. A fluorescent secondary antibody was applied. Nerve fibers were then quantified by two observers using fluorescent microscopy. Data were analyzed using a multivariate Poisson regression model. Variables studied were age, gender, anatomical location, bone-related compartment, fiber type and fiber count. Results: 54 bones were collected from 29 bodies. Six thoracic vertebrae, four skulls, five humeri and seven radii, 17 femora and 15 tibiae were analyzed. Sixteen bodies were female. Average age was 84 years (range 66-99). Innervation density was highest in the periosteum, followed by bone marrow and cortex (ratio 100:54:8). Periosteal fibers were organized in a net-like structure. The thoracic vertebra was the most densely innervated bone, while the skull received least innervation. Bone innervation density decreased with age. No difference in innervation density between genders was observed. Conclusion: This study provides novel insights in the sensory innervation of the healthy human skeleton across various bones, making the results relevant to the general population. The periosteum was the most densely innervated bone-related compartment and the thoracic vertebra the most densely innervated bone studied. The present results provide an explanation for the severe pain experienced by patients suffering from skeletal disease or injury and might aid in improving treatment of skeletal pain.

987

P029: Establishment and Validation of the Medium-Size, Surgically Feasible Rabbit Model for Brucellar Spondylodiscitis

Xiaoyu Cai ^1,2 , Tao Xu ³ , Yakefu Abulizi ³ , Maierdan Maimaiti ³ , and Weibin Sheng ³

¹ First Affiliated Hospital of Xinjiang Medical University, Urumqi, China, Department of Spine Surgery, Urumqi, China

² Saarland University, Homburg (Saar), Germany

³ First Affiliated Hospital of Xinjiang Medical University, Urumqi, China, Urumqi, China

Introduction: Brucellar spondylodiscitis, the most prevalent and significant osteoarticular presentation of human Brucellosis, is difficult to diagnose and usually yields irreversible neurologic deficits and spinal deformities. However, no animal models of Brucellar spondylodiscitis exists allowing for preclinical investigations. Material and Methods: Standardized bony canals were drilled with a Kirschner wire below the upper-end plate of the 6th lumbar vertebrae into the vertebral body of rabbits. Attenuated Brucella melitensis vaccine and normal saline were injected into the canals for the experimental and sham surgery groups, respectively. Rabbits receiving no surgery served as normal controls. Animal status and treatment outcomes were evaluated by in vivo radiographic analyses, including plain radiography, computed tomography reconstruction, and magnetic resonance imaging (MRI), at both 1 and 2 months postoperatively. After the radiographic assessments at 8 weeks postoperatively, all animals were sacrificed, and the targeted tissue including vertebral and paravertebral structures were harvested for further macroscopic and histological analyses. Results: In the experimental group, 1 rabbit were eliminated due to incision infections at 1 month postoperatively. All survival rabbits presented signs of emaciation, and decreased activity. The T2 weighted image at 2 months postoperatively observed iso-signal or slight hyper-signal intense within the L5 and L6 vertebral bodies and hyper-signal intense within the paravertebral soft tissue. According to the modified MRI classification system, the compound type was the most frequent type (74%) followed by the paraspinal abscess or psoas abscess type (18%) and discitis type (8%). The featuring predominant lymphocyte and monocytes infiltration with sparsely distributed epithelioid cells and multinucleated giant cells was found in the biopsied paravertebral structures. Conclusion: The medium-sized, surgically feasible rabbit model in this study provides a promising in vivo setting for further preclinical investigations of Brucellar spondylodiscitis.

1111

P030: How Accurate Is the Spine Surgery Literature?

Thiago Montenegro ¹ , Kevin Hines ¹ , Paul Partyka ² , and James Harrop ¹

¹ Thomas Jefferson University, Neurosurgery, Philadelphia, USA

² Rowan University, Glassboro, USA

Introduction: The reference list is an important part of a scientific article that serves to confirm the accuracy of the authors’ statements. The goal of this study was to evaluate the reference accuracy in the field of spine surgery. Material and Methods: Four major peer-reviewed spine surgery journals were chosen for this study based on their subspecialty clinical impact factor: Spine J, Spine (Phila Pa 1976), J Neurosurg Spine, and Global Spine J. Sixty articles in each journal from the 12 issues of Spine (Phila Pa 1976), Spine J, and J Neurosurg Spine, and 40 articles from the 8 issues of Global Spine J were selected. All the articles were published in 2019 and were selected using a computer-generated number, for a total of 220 articles. From the reference list of each article, one reference was again computer generated and checked for a citation or quotation error. Results: Results indicate that 84.1% of articles have a minor citation error, 4.5% of articles have a major citation error, 9.5% of articles have a minor quotation error, and 9.1% of articles have a major quotation error. Despite these statistics, J Neurosurg Spine had the fewest citation errors compared to the other journals evaluated in this study. Using chi-square analysis, no association was determined between the occurrence of errors and potential markers of reference mistakes. Still, statistical significance was found between the occurrence of citation errors and the spine journals tested. Conclusion: In order to advance medical treatment and patient care in spine surgery, detailed documentation and attention to detail is necessary. The results from this study illustrate that improved reference accuracy is required.

1535

P031: Ligamentum Flavum Injury Promotes Disc Degeneration in vivo

Louis Amorosa ¹ , Dan Viola ¹ , Kevin Burt ^1,2 , Joseph Lombardi ¹ , and Nadeen Chahine ^1,2

¹ Columbia University Medical Center, Department of Orthopaedic Surgery, New York, USA

² Columbia University, Department of Biomedical Engineering, New York, USA

Introduction: The ligamentum flavum (LF) can contribute to spinal stenosis when it hypertrophies. This oftentimes occurs concurrently with disc degeneration; however, this process is not fully understood. We created a live small animal model of LF injury with varying severity and examined the effect on LF and intervertebral disc (IVD). Methods: Prior IACUC approval was obtained. Eighteen adult male Sprague Dawley rats (3 months old, ∼300 grams) were allocated to three groups. Injury: After confirmation with fluoroscopy, a needle was placed into the LF under direct visualization via the interlaminar space of L3-4. Two passes were made with the needle through the LF into the epidural space. Group I (n = 6) underwent injury with a 22G needle (injury 22G). Group II (n = 6) underwent the same midline incision but with no needle placement (sham group). Group III (n = 6) had the same injury procedure performed but with a 30G needle (injury 30G). All animals were euthanized 7 days later. Fluoroscopy analysis: All animals underwent lateral pre- and post-intervention fluoroscopic imaging of the spine for radiographic measurements of intervertebral disc height index (DHI). Histological analysis: Following radiographic analysis, the lumbar spine was removed en bloc for histologic analysis. LF histological grading was performed on the injured, and immediate superior/inferior levels for elastin degradation, fiber alignment and cell morphology. IVD histological grading was performed on the injury level disc and immediate superior/inferior discs. Histological grading evaluated changes in cellularity and morphology of the annulus fibrosis (AF), integrity of border between AF and nucleus pulposus (NP), and cellularity and morphology of the NP. Scores from the 3 levels were pooled per animal for group comparisons. Statistics: Differences between groups were analyzed with Student’s t-test (Graphpad Prism, San Diego CA), with P < .05 considered significant. Results: In 22G injury group, average DHI decreased by 6.1% (P < .001). In 30G injury group, average DHI decreased by 3.2% (P < .01). In the sham group, average DHI decreased by .6% (P < .05). Injury with 30G or 22G needles led to cellular infiltration around the injury, loss of aligned matrix organization and higher rates of elastin degradation. Histological scoring of the LF was significantly higher in the 30G and 22G injured LF compared to sham (P < .05). Histological evidence of disc degeneration was also evident with mild degeneration in the sham group, characterized by changes in AF cellularity. In the 30G injury group, moderate degeneration was observed, characterized by serpentine structure and chondrocyte-like cell presence throughout the AF. In the 22G injury group, severe disc degeneration was observed where a loss of NP/AF border, loss of NP cellularity, and cartilage formation was observed throughout the NP. Discussion: Isolated injury to the LF resulted in decreased disc height and histological disc degeneration 7 days after injury. LF damage may play a role in disc degeneration, LF hypertrophy, and spinal stenosis. This suggests that commonly performed clinical procedures such as interlaminar epidural injections or minimally invasive decompressions in which a small part of the LF is injured or removed, may initiate or propagate further disc degeneration.

1613

P032: 3D Morphology of Cervical Vertebral Endplate Anatomy: A Literature Review

Wilson Liu ^1,2 , William Parr ^1,2,3 , William Walsh ¹ , and Ralph Mobbs ²

¹ Surgical and Orthopaedic Research Laboratories, Sydney, Australia

² NeuroSpine Surgery Research Group, Sydney, Australia

³ 3DMorphic Pty Ltd, Sydney, Australia

Introduction: Cervical surgeries (anterior cervical discectomy and fusion (ACDF) and total disc replacement (TDR)) are relatively common procedures that typically involve the insertion of interbody devices into the cervical interbody spaces. These spaces are defined superiorly and inferiorly by the adjacent vertebral endplates. Therefore, it is important that there is good data and understanding of cervical endplate morphology. Thus, the aim of this literature review is to review the current literature investigating cervical endplate morphology and how it is affected by age and gender. Material and Methods: A literature review was conducted using 2 electronic databases. Combinations of the following search terms were searched: “endplate”, “cervical”, “cervical vertebrae”, “morphology” and “3D”. Relevant articles (n = 11) were selected by the authors and reviewed. The citation lists of the selected articles were also searched for additional relevant studies (n = 1). Results: Current literature on cervical endplate morphology (n = 12 articles) is limited. Literature concurred that cervical endplate diameters (anterior-posterior and transverse) and surface area generally increased with descending vertebral level and increasing age. However, the relationship between age and cervical endplate diameters and surface area was only investigated by a single study, limiting the confidence in the results. From the studies, females generally had smaller cervical endplate diameters and surface areas than males. The studies also agreed that inferior vertebral endplates were generally more concave than superior vertebral endplates, which were relatively flat. Whilst studies agreed that the concavity apex of superior endplates was generally located posteriorly on the endplate surface, conflicting results were found on the position of concavity apices on the inferior endplates. The relationships between gender, age and cervical endplate concavity and concavity apex location were not well reported. Conclusion: Current literature on 3D cervical endplate morphology is lacking. Existing studies are based on linear and area parameters measured directly from cadaveric spines or from two-dimensional (2D) imaging modalities (computed tomography (CT) and X-rays) in specific planes. These 2D parameters do not fully capture the true 3D shape of cervical endplates and studies may differ on how they define these parameters, making data difficult to compare. Thus, further studies utilising methods that successfully capture the 3D shape of cervical endplates are required. Greater morphological knowledge on cervical endplates can help define the morphology of normal cervical interbody spaces and help guide designs of appropriately fitting disc implants in the future.

1615

P033: Cervical Interbody Spaces Vary by Level and are Always Asymmetrical; Most Symmetrical Cervical Interbody Devices Will Not Fit Well in the Anatomical Space

Wilson Liu ^1,2 , William Parr ^1,2,3 , Gideon Budiono ² , Melvin Ng ^1,2 , William Walsh ¹ , Ralph Mobbs ²

¹ Surgical and Orthopaedic Research Laboratories, Sydney, Australia

² NeuroSpine Surgery Research Group, Sydney, Australia

³ 3DMorphic Pty Ltd, Sydney, Australia

Introduction: Cervical interbody devices come in many different shapes and dimensions. These devices must fit within the interbody space. Current literature on cervical interbody space morphology is limited with previous studies utilising methods that do not fully capture the complex three-dimensional (3D) shape of disc spaces. Improving our understanding of 3D cervical interbody space morphology could help enhance future device designs and improve clinical performance. Thus, the aim of this study is to perform a quantitative 3D morphological analysis of cervical interbody spaces and to assess the impact of gender, size and age on interbody space morphology. Material and Methods: A large retrospective in-vivo analysis of the 3D cervical disc space morphology of patients (n = 156 patients, 780 interbody spaces, 1560 endplates) with clinically deemed non-pathological cervical spines was conducted. 3D surface reconstructions of each patient’s cervical anatomy were generated from their computed tomography (CT) scans, and each vertebra’s endplates were segmented (C2 inferior to C7 superior). The endplate reconstructions were resampled using geometrically homologous landmark coordinates and paired into the five disc spaces. Shape (principal component) analysis was performed on the 3D landmark data to identify the main patterns of interbody space shape variation. The shape patterns were analysed against age, gender and size to determine relationships between these parameters and patterns. Results: Size and size-associated differences were identified as the main mode of shape variation in cervical interbody spaces. Females had significantly smaller interbody spaces than males. In addition to size effects, significant but weak correlations between age and disc space surface area were found for all cervical disc space levels, with the strength of the relationship increasing down the cervical spine. 3D shape varied significantly between disc spaces of different cervical levels. Significant morphological differences between cranial and caudal endplates were identified, demonstrating the interbody spaces are asymmetrical. Conclusion: This study showed cervical interbody spaces are asymmetrical (top and bottom) (P < .000001). Interbody device designs (primarily anterior cervical discectomy and fusion (ACDF) cages) are generally symmetrical and flat; device-endplate mismatch can cause post-operative, device-related complications like subsidence and device migration. Importantly, the results showed shape differences between different levels of the cervical spine. This suggests that for example, devices fitting the C2-3 level may not be suitable for the C6-7 level, even within the same patient, due to shape differences (not just size). We found significant relationships between age and disc space surface area, with the strength of the relationship increasing down the spine; this may suggest that lower level cervical disc spaces are more susceptible to spondylotic changes than higher level cervical disc spaces.

1652

P034: Clinical Correlation Between Muscle Damage and Functional Disability After Open Lumbar Fusion Surgery. Is MISS Really Better?

Rushama Tandon ¹

¹ Northern Railway Central Hospital, Orthopedics, New Delhi, India

Introduction: There are few studies which have analyzed the functional loss and recovery pattern of muscles after open lumbar surgery. The study validates the improvement in function by improved ODI in spite of significant muscle damage. Materials and Methods: 30 patients who underwent open lumbar spine fusion surgery at authors’ institution from August 2013 to May 2015 were included in this study. Patients were evaluated functionally by VAS and ODI scores, biochemically by CPK values, electro physiologically by EMG/NCV and radiologically by MRI and Xrays. at out-patient department of authors’ institution preoperatively and on follow up at 6 months post-operatively following open Lumbar surgery. Results: Mean preoperative and 6 months postoperative CPK values were133.07 ± 17.57 U/L and 139 ± 17.7 U/L respectively L (P-value < .001). Mean preoperative and 6 months postoperative VAS scores for backache were 6.73 and 3.27 respectively. Mean ODI score preoperatively and 6 month postoperative were 41.6 ± 5.51 and 22.4 ± 4.48 respectively (P-value < .001).Preoperatively, 20% patients had polyphasic configuration in electro physiologic studies whereas at 6 months postoperative period, all patients had polyphasic configuration (P-value < .001). Preoperative and 6 month postoperative mean cross sectional area (MCSA) of multifidus was 742.67 ± 76.62 mm² and 598.27 ± 66.38 mm² respectively (P value < .001) with all cases having grade 2 atrophy. Conclusion: In spite of damage to lumbar paraspinal muscles during open lumbar fusion surgery as indicated by reduction in MCSA of multifidus by MRI and denervation of multifidus by EMG study, there was improvement in back pain and quality of life of patients. These improvements may be due to increase in stability of unstable lumbar spinal segment after lumbar fusion surgery. The MRI findings do not translate into clinical disability compared to Minimally Invasive techniques.

1753

P035: Induction and Chronological Observation with Magnetic Resonance Imaging of Congenital Spinal Deformities in Mice

Haruki Ueda ¹ , Takuya Iimura ¹ , Hiroshi Moridaira ¹ , Satoshi Inami ¹ , Hiromichi Aoki ¹ , Yoshiteru Seo ^2,3 , and Hiroshi Taneichi ¹

¹ Dokkyo Medical University, Orthopaedic surgery, Shimotsuga, Japan

² Dokkyo Medical University, Regulatory Physiology, Shimotsuga, Japan

³ Aichi Gakusen University, Home economics, Okazaki, Japan

Introduction: Congenital spinal deformities are sometimes progressive and even life threatening over time, and it is very critical to provide appropriate treatment at proper timing. Currently clinical prediction of the deformity prognosis largely depends on radiographic morphology. Despite the powerful analytic ability, MR imaging has been scarcely reported as predictor of the prognosis of congenital spinal deformities due to its longer imaging time, which often requires younger patients to be sedated and set the hurdle higher for its use among them. The purpose of this study is to create the congenital scoliosis mouse model, to observe them chronologically with soft X-ray and MR imaging, and to see if this modality is helpful for precise observation of this deformities. Material and Methods: This project was approved by the Animal Research Councils of our university by the judgement reference number of 988. The mouse models of congenital scoliosis were created by maternal carbon monoxide exposure for seven hours on the 9.5th day of gestation. The new-born mice were screened by soft X-ray, and those with spinal anomalies were followed with repetitive soft X-ray image and 7T MR images. After three separate sessions of MRI, the mice were euthanized and another MRI were taken. The changes in the imaging studies were assessed. Results: Three congenital vertebral anomalies in two mice were created. They were one block vertebra, one unsegmented hemivertebra, and one adjacent wedge vertebrae. All of them did not progress and no degenerative change occurred in our follow-up. MR images clearly showed the morphology of the anomalies which had characteristics of the non-progressive congenital vertebral anomalies in human studies. Conclusion: The production of the congenital scoliosis mice and their chronological follow up were performed with soft X-ray and 7T MR imaging. MR imaging were very powerful to depict the local morphology and to distinguish osseous and intervertebral structures of the small mice spine as well as small arteries around the spine, while soft X-ray image could only show their global curve appearance. The strength of this study is our chronological and detailed observation of spinal deformities with MRI over the growth period of mice. Our limitation is the small number of cases and all were relatively stable pattern among various congenital spinal anomalies.

Biomechanics

44

P036: Role of Muscles, Abdominal Pressure, and Thoracolumbar Fascia in Thoraco-Lumbar Spine Stability

Ibrahim El Bojairami ¹ and Mark Driscoll ¹

¹ McGill University, Mechanical Engineering, Montreal, Canada

Introduction: Although the spinal column is inherently unstable [1], the coordination between muscles [2], [3], their intramuscular pressure (IMP), and intra-abdominal pressure (IAP) generated by the co-activation of abdominal muscles [4], as well as the passive engagement of the thoracolumbar fascia (TLF) [1], is believed to support spinal static stability. With little information on the exact contribution of each tissue, besides the poor judgement due to simplified models, the purpose of this research was to use a novel, validated, and fully representative finite elements (FE) model of the spine to investigate the contribution of each of the torso muscles, IMP, TLF, and IAP, as well as the collective effect on equilibrium static spinal stability. Material and Methods: A novel validated spine FE model has been developed by the authors and further used for the purpose of this study. The model put forth includes accurate models of all thoracic and lumbar vertebral bodies (VBs), intervertebral discs (IVDs), major spine muscles inclusive of their IMP, TLF, and a model of IAP. A previously validated spinal perturbation of 350N flexion force was applied at T1 [5]. Case-studies of including each tissue on its own, as well as the different combinations between those, were investigated. For each scenario, in-plane lumbar VBs horizontal displacements were recorded to investigate equilibrium static stability, defined as the new behavior (position) of the spine with respect to the initial condition prior to applying the perturbation [6]. Muscles activation was based on recorded EMG muscle forces [7] while IAP was introduced as an increasing pressure of around 67 mmHg (9 KPa) maximum value in an abdominal cavity [8]. Results: With the upright torso being the initial position, applying the 350N perturbation on the model inclusive of only the VBs and IVDs was identified as the most unstable position for the current study. The activation of IAP, muscles, and TLF resulted with individual contributions of 24%, 53.8%, and 77% respectively. Other combinations results fell between 60 and 93%, with the 93% being the result of all tissues activated together. Another incredible finding was the approximately 46% drop in IMP developed by back muscles upon the inclusion of TLF, suggesting its role stabilizing and preventing excessive muscles pressurization. Conclusion: The enclosed research suggests that the included muscles along with their IMP, IAP, and TLF are the major contributors to equilibrium static spinal stability as defined by this paper, with every other torso organ contributing to only the rest 7%. Interestingly, even though the TLF is a passive tissue, its material properties and strong attachments to the vertebral bodies leverage it to store excessive loads as a protective measure. This was supported by the resultant forces collected at the TLF-vertebraes attachments which summed up to around 244N, all acting as antagonistic forces to the applied one. Results of the current research assist in better understanding the notion of spinal stability as literature is still pressing for more sophisticated models able to assess more modes of stability.

52

P037: Mechanical Evaluation of Stress Shielding in the Lumbar Musculoskeletal Soft Tissues in Low Back Pain: A Finite Element Study

Emily Newell ¹ , Mark Driscoll ¹ , and Jean Ouellet ²

¹ McGill University, Mechanical Engineering, Montreal, Canada

² McGill University Health Centre, Paediatric Surgery & Surgery, Montreal, Canada

Introduction: While low back pain (LBP) is a common affliction, the pathomechanism of LBP continues to allude researchers. However, with the growing evidence from research surrounding the biomechanical importance of fascia, this tissue may play a role in the progression of LBP. Additionally, morphological and material property changes to lumbar muscles, specifically the erector spinae (ES) and multifidus (MF) whose primary role is to stabilize the spine during motion, have been correlated with LBP [1, 2]. These modifications, as well as reduced shear strain and increase in TLF thickness [3] in LBP patients, may be consequences of stress shielding defining a load allocation bias occurring in the soft tissues within the lumbar spine. Thus, the aim of this novel study is to compare healthy and LBP-affected models of musculoskeletal systems to determine if such a stress shielding bias exists as a result of soft tissues properties being altered. Material and Methods: Using a finite element platform (ANSYS v19.2, Canonsburg, USA), two models were created and objectively compared under a 30-degree flexion, one depicting a healthy lumbar spine, and another affected by LBP. Each model was composed of volumetric STL files of the lumbar vertebrae (L1-S1), intervertebral discs (IVDs), and soft tissues including the MF, ES, TLF, and tendons. Material properties used were based upon published literature and were assumed to be linear and isotropic. The LBP model demonstrated morphological and stiffness changes to the MF, ES, and TLF as documented in previously published literature involving LBP patients. Both models were indirectly validated against published finite element models and patient data simulating 30-degree flexion in the spine [4, 5]. Results: Validation supported the models as results demonstrated similar trends in IVD pressure and vertebral rotation. Negligible differences from IVD pressure were experienced from L1-L4 but IVD pressure increases at L5 when comparing the LBP model to the healthy model. Compared to the healthy model, the overall normal stress exhibited by soft tissues in the LBP model increased by 15.5%. Normal stress exhibited by the LBP model’s MF, ES, and TLF increased by 2.8, 5.6, and 15.6% respectively relative to the healthy model. Negligible change (<.7%) in total deformation was demonstrated between models. Conclusion: Results from the present research suggest that stress allocation in the lumbar spine with LBP will be directed towards the L5 level as evidenced by the L5 IVD pressure increase. Additionally, while the LBP model demonstrated an overall increase in soft tissues stress, 99.8% of the stress increase was distributed towards the TLF. Thus, LBP may be causing the TLF to undergo stress shielding, preventing the ES and MF from receiving loading, potentially resulting in further atrophy and inability to distribute loading. Furthermore, if the soft tissues are unable to withstand loading, the patient may subconsciously recruit other muscles to accommodate the desired motion, resulting in physiological remodeling of those newly recruited muscles. Therefore, this novel study suggests that the onset and progression of LBP may be due to stress shielding caused by mechanical changes to the TLF.

103

P038: The Investigation of Physiological Stress Shielding Within the Lumbar Soft Tissues of Musculoskeletal Systems Affected by Ipsilateral Low Back Pain: A Finite Element Study

Emily Newell ¹ , Mark Driscoll ¹ , and Jean Ouellet ²

¹ McGill University, Mechanical Engineering, Montreal, Canada

² McGill University, Department of Paediatric Surgery & Surgery, Montreal, Canada

Introduction: Low back pain is a public health crisis with nearly 85% of cases being unattributed to a specific cause [1]. However, with the emergence of research concerning fascia’s contributions to spinal biomechanics, fascia may contribute to the progression of low back pain. For example, the thoracolumbar fascia (TLF) has demonstrated reduced shear strain and increased morphological thickness in such patients [2]. Likewise, previous studies have correlated low back pain with mechanical property changes in spine-stabilizing lumbar muscles – the multifidus (MF) and erector spinae (ES) [3, 4]. These tissue modifications suggest the presence of stress shielding within the lumbar spine. Thus, the objective of this study is to analyze soft tissue stress distributions within healthy and ipsilateral low back pain (ILBP) musculoskeletal systems, to investigate whether stress shielding can lead to the progression of low back pain. Methods: Using a finite element platform, ANSYS (v19.2, Canonsburg, USA), two finite element models (FEMs) demonstrating healthy and ILBP undergoing flexion were developed. Models depicted the lumbar vertebrae (L1-S1), intervertebral discs (IVDs), and soft tissues (MF, ES, TLF, and associated tendons). Material properties were selected based on published literature. To demonstrate ILBP, tissues laterally located to the right of the vertebral column (denoted as “symptomatic tissues”) were modified to reflect the mechanical properties of ILBP patients documented in previous clinical studies [2, 4, 5]. The left lateral region (“asymptomatic tissues”) remained unchanged. Model validation preceded testing. Results: Model validation was achieved as results demonstrated good agreement in IVD pressure and intervertebral rotation of published patient data and in silico spine models [6, 7]. Compared to healthy tissues, the average normal stress exhibited by the ILBP model’s soft tissues increased by 10.9 kPa. Within the ILBP FEM, the MF, ES, and TLF demonstrated a cumulative tension change of +2.4, -1.5, and +9.3%, respectively, relative to their healthy counterparts. Furthermore, the symptomatic MF, ES, and TLF tissues exhibited changes in average tension by +8.3, -1.5, and +16.1%, respectively, whereas the corresponding asymptomatic tissues experienced a -4.0, -2.0, and +.4% change in tension, respectively. Conclusion: Results suggest a stress allocation bias within ILBP musculoskeletal systems, specifically directed towards the symptomatic ILBP tissues. While the ILBP FEM increased by 10.9kPa in average stress in the soft tissues, relative to the healthy FEM, 99.8% of this increase was directed towards the TLF. Furthermore, both the asymptomatic and symptomatic TLF exhibited the largest changes in average tissue tension relative to their respective MF and ES tissues, further indicating the TLF withstands the majority of the increased stress within the ILBP FEM. Thus, ILBP may be causing the symptomatic TLF to initiate stress shielding, preventing the adjacent soft tissues from receiving loading, resulting in further atrophy and an inability to distribute stress. To compensate, patients may subconsciously recruit additional soft tissues to achieve the desired motion, potentially leading to irregular muscle activation, distorted force balances, and cyclical stress shielding. Ultimately, this novel study suggests stress shielding within lumbar soft tissues may lead to the progression of low back pain.

209

P039: A Novel Universal Robotic Spine Model with Pneumatic Muscles to Study Spinal Stability

Brittany Stott ¹ and Mark Driscoll ¹

¹ McGill University, Montreal, Canada

Introduction: Affecting 75-85% of individuals, low back pain remains one of the largest economic burdens on health and welfare systems [1]. Furthermore, the etiology and pathomechanism of back pain continue to elude researchers, demonstrating the need for new systems to advance musculoskeletal biomechanical research. Previous medical advancements with respect to low back pain often included ex vivo cadaveric lumbar spines but neglected the spinal muscles’ role in spinal stabilization. Some studies replaced such muscles with cables within cadaveric spinal studies [2,3]. However, these methods may be difficult and, at times, lack realism when performing experiments ex vivo, indicating the need for future studies to develop alternative methods to determine the paraspinal muscles’ effect on stability experimentally. Thus, the objective of this study is to develop and validate a new experimental spine model consisting of an analog thoracolumbar spine with active and controlled pneumatic muscles to further the understanding of spine biomechanics. Material and Methods: The robotic spine model was designed, complete with analog bones (3B Scientific, Germany), McKibbens pneumatic muscles (PMs) modelling posterior spine muscles, and artificial thoracic and abdominal-pelvic cavities. To allow automatic control of the system, the model was automated through a proportional-integral-derivative control system developed on LabVIEW. The control system includes automatic valves (Bürkert, Germany) allowing for muscle and cavity inflation, a position tracking system (Polhemus, USA), pressure sensors (OMEGA, Canada), and force sensors (Tekscan, USA). The position tracking system, pressure sensors, and force sensors allow spinal displacement, intramuscular pressure (IMP), and intradiscal pressure (IDP) data to be recorded, respectively. A Data Acquisition System (National Instruments, USA) allowed data acquisition and transmission between the benchtop model and the computer administering the control algorithms. Subsequently, towards validation, the spine model was subjected to a vertical compressive load and the control system automatically regulated airflow to the PMs and cavities to correct the deflection from the initial position based on data from the tracking system. Results: The spine model’s control system allowed for automatic reaction to counteract instability when subjected to a compressive load. The activated muscles decreased the range of motion and strongly influenced the stability of the spine model. Ultimately, a linear IMP-force relationship was observed for the PMs which is comparable to known biological data, specifically the anterior tibialis muscle in rabbits [4]. The PMs produced a maximum force of 250 N when inflated, which is within the range of the physical biological limit [5]. When subjected to a load, the maximum IMP was 552 kPa, and the IDP measured on the model was .08 MPa. Conclusion: The developed robotic spine model successfully underwent preliminary validation thus establishing its relevance as a future experimental model to study spine biomechanics. Moreover, the IMP-force relationship corroborates the PMs as a reliable model for biological volumetric muscles. This robotic spine model allows each muscle and artificial thoracic and abdominal-pelvic cavities to be controlled individually and, consequently, future experiments can analyze the consequence of variations in intra-abdominal pressure and IMP on spine stability.

968

P040: Effect of Cage Position and insertion Angle in the Oblique Lumbar Interbody Fusion: A Finite Element Study

Jungwoo Hur ¹ , Min Seok Kim ² , Jae-Taek Hong ¹ , and Sung-Jae Lee ²

¹ Eunpyeong St. Mary's Hospital, The Catholic University of Korea, Neurosurgery, Seoul, South Korea

² Inje University, Biomedical Engineering, Gimhae, South Korea

Introduction: Oblique lateral interbody fusion (OLIF) is considered a useful surgical option for various lumbar degenerative diseases with favorable clinical results and few complications. However, retroperitoneal prepsoas approach compels cage to be inserted more obliquely compared to direct lateral transpsoas approach, where cage is inserted more vertically. Moreover, the effect of cage insertion angle on postoperative cage stability and subsidence has not been fully understood yet. The purpose of the present study was to evaluate the biomechanical effect of cage position and insertion angle on postoperative stability and subsidence following oblique lateral interbody fusion using finite element (FE) model. Material and Methods: Previously validated 3-dimensional FE model of intact lumbar spine (L4-5) was used. For the vertebral fusion procedures, PEEK (E = 3500 MPa, v = .3) cage (L40 * W22 * H12 * A12, GS Medical Co., Ltd., Korea) with titanium (E = 110000 MPa, v = .33) pedicle screws (Ø6.5 × 45 mm, GS Medical Co., Ltd., Korea) were used. 6 surgical models were created according to cage positioning and insertion angles (Type A: anterior 1/3, Type B: center, Type C: posterior 1/3, Type D: anterior 25°, Type E: Center 25°, Type F: Posterior 25°) 10Nm pure moment of flexion/extension, lateral bending and axial rotation was applied at the superior surface of L4 endplate with a compressive follower load of 400 N. The cage and pedicle screw—vertebral body interface behavior were assigned ‘tie’ contact condition to simulate complete postoperative bone union. In addition, the likelihood of yield of cage and the risk of the subsidence were compared and analyzed using Peak von Mises Stresses (PVMS) values occurring in each type of cage and cancellous bone, respectively. Results: All 6 models showed lower stress values as compared to the yield strength of PEEK (75 Mpa). 0° models demonstrated (Types A, B and C) significantly lower likelihood of cage yield compared to 25° models (Type D, E and F ; 33%, 33% and 30% vs 49%, 47% and 33%, respectively), suggesting anteriorly positioned cage with less insertion angle is more stable. Similarly, in investigating the risk of subsidence, the stresses recorded in the cancellous bone for all 6 models were less than the reported yield strength of the cancellous bone (16.3Mpa). 0° models demonstrated (Types A, B and C) significantly lower risk of subsidence compared to 25° models (40%, 57% and 40% vs 68%, 54% and 67.6%, repectively), suggesting anterior or posterior positioned cage with less insertion angle lowers the risk of subsidence. Conclusion: Our study demonstrated that during OLIF, insertion of cage more anteriorly with less insertion angle provided better stability and less chance of subsidence. This study suggests that cage should be inserted more anteriorly and vertically during OLIF procedure to maintain postoperative stability and to reduce cage subsidence.

1075

P041: Discectomy Tool Mechanical Testing in Cadaveric Spine

Trevor Cotter ¹ , Mark Driscoll ¹ , and Rosaire Mongrain ¹

¹ McGill University, Mechanical Engineering, Montreal, Canada

Introduction: The push towards minimally-invasive (MI) surgeries as a method of improving surgical outcomes has been augmented by innovation in the medical device industry. Studies show that MI discectomy, or removal of the intervertebral disc (IVD) of the spine, can shorten surgical and recovery times as well as decrease complications (Mo et al. 2018; Phan et al. 2015). CONCORDE Clear (DePuy Synthes; Boston, USA) is a novel suction curette device that has been estimated to save $1300 USD per procedure and reduce surgeon fatigue while being 4 times faster and removing twice as much tissue as traditional curettes (Mo et al. 2018). However, there is no published analysis of the forces and torques exerted by surgeons while using any of these tools. Materials and Methods: An analog of the CONCORDE Clear shaft was manufactured with the same tip length and curvature while the overall length was reduced to minimize bending during the test. The shaft was connected to a force and torque load cell of 2.5 kN and 25 Nm, respectively (662.20D-01, MTS Systems Corporation; Minneapolis, USA). Fresh frozen cadaveric torsos were thawed and subjected to insertion and torsion tests of up to 20mm disc penetration and ±45° rotation. The linear and torsion tests were repeated 3 and 5 times respectively, from both sides at all lumbar IVDs on both cadavers. Data was analyzed to compare spinal levels and penetration depths. Results: The average force peak for the tests was 37 N during insertion and 29 N during retraction at 20 mm IVD penetration. Peak torques ranged from 219 to 464 N.mm at 45° torque against the vertebral endplate. These varied across spinal levels. Additionally, the forces lowered as tissue was removed from the IVD. Conclusion: This test quantifies the forces and torques present using an analog of the CONCORDE Clear, perhaps corroborating previous claims that it was less fatiguing than other curette tools (Mo et al. 2018). Forces and torques tested can be used to inform future tools designs or provide references for surgeons. This study can be applied to smart tool development and other operating room innovations.

Acknowledgements

The authors thank Elisabeth Laroche at École de technologie supérieure (ÉTS) (Montreal, Canada) and Hôpital du Sacré-Coeur (Montreal, Canada) for their help in performing the testing. Research grant support was provided by the Natural Sciences and Engineering Research Council of Canada (NSERC), Quebec Consortium for Industrial Research and Innovation in Medical Technology (MEDTEQ), CAE Healthcare (Montreal, Canada), and DePuy Synthes Companies (Raynham, USA).

References

1. Mo, Fred, Philip Yuan, Ali Araghi, and Hassan Serhan. 2018. “Time Savings and Related Economic Benefits of Suction-Curette Device for Transforaminal Lumbar Interbody Fusion Discectomy.” International Journal of Spine Surgery 12(5): 582–86.

2. Phan, Kevin et al. 2015. “Lateral Lumbar Interbody Fusion for Sagittal Balance Correction and Spinal Deformity.” Journal of Clinical Neuroscience.

1328

P042: Use of Smartphone in the Elderly Population: A Comparative Study and Epidemiological Profile

Yasmin de Rezende Beiriz ¹ , Amanda Grippa Piffer ¹ , Alessandra Tieppo ^1,2 , Aline Fonseca Sandrini ¹ , and Charbel Jacob Jr ^1,2

¹ Escola Superior de Ciências da Santa Casa de Misericórdia de Vitória (EMESCAM), Vitória, Brazil

² Hospital Santa Casa de Misericórdia de Vitória, Vitória, Brazil

Introduction: Accompanying the aging of the population, difficulties and physical and physiological changes arise, such as in the discrimination of sounds, decreased visual acuity and the peripheral visual field, which may make it difficult to insert technology in the elderly's daily life. In addition, the fact that they were educated at a time when smartphones were less ubiquitous and complex can influence their performance with these devices, favoring the appearance of problems related to the spine. The use permanent cell phones, associated with poor posture, can have a result similar to that of repetitive stress / strain injury, which can inflame the neck ligaments, lead to nervous irritation and increased curvature of the spine. This study aims to outline the profile of smartphone use of the elderly population. Material and Methods: Cross-sectional, analytical, observational, quantitative study, with a digital interview directed to the elderly who use the smartphone. The responses collected were analyzed according to the objectives of the work. Results: Of the 508 respondents, 9.3% were elderly. 77.3% of the elderly do not require the use of smartphones in their occupations. 48.4% of the elderly interviewed were retired, 42% worked full time, 6.3% worked part time and 2.1% were unemployed. 50.5% of the elderly consulted had completed higher education. 43.2% of the elderly use the device at night, 36.4% use it in the morning and 20.5% in the afternoon. 52.3% of this audience uses smartphones from 1 to 3 hours a day, against 25% who use 3-5 hours, 11.4% who use more than 5 hours and 11.4% who use less than 1 hour. 45.5% of this group use the smartphone mainly for calls, 27.3% for access to social networks, 13.6% for browsing the internet, 4.5% for games, 4.5% for photographing and 4.5% for other purposes. Conclusion: The minority of smartphone users were elderly. Of these, most did not use the smartphone in their occupation, were retired and had completed higher education. The most common period of use is at night, with 1 to 3 hours a day. Most of these audiences use their smartphones to make and receive calls. The use of smartphones by the elderly is growing, making it necessary to study the subject to prevent possible health-related problems.

1616

P043: Proposed Objective Scoring Algorithm for Walking Quality, Based on Relevant Gait Metrics: The Simplified Mobility Score: SMoS (Observational Study)

Callum Betteridge ^1,2,3,4 , Ralph Mobbs ^1,2,3,4 , and Daniel Ho ^1,2,3,4

¹ University of New South Wales, Faculty of Medicine, Sydney, Australia

² NeuroSpine Clinic, Sydney, Australia

³ NeuroSpine Surgery Research Group (NSURG), Sydney, Australia

⁴ Wearables and Gait Assessment Group (WAGAR), Sydney, Australia

Introduction: Walking is a fundamental part of living, and its importance is not limited by age or medical status. Reduced walking speed (WS), or gait velocity, is a sign of advancing age, various disease states, cognitive impairment, mental illness, and early mortality. Activity levels, as defined in the literature as “daily step count” (DSC), is also a relevant measure of health status. A deterioration in our walking metrics, such as reduced WS and DSC, is associated with poor health outcomes. These objective measures are of such importance, that walking has been dubbed “the 6th vital sign”. We report a new objective measure that scores walking using the relevant metrics of walking speed and daily step count, into an easy-to-understand score from 0 (nil mobility) – 100 (excellent mobility), termed the Simplified Mobility Score (SMoS™). We have provided equal weighting to walking speed and daily step count, using a simple algorithm to score each metric out of 50. Material and Methods: Gait data was collected from 182 patients presenting to a tertiary hospital spinal unit with complaints of pain and reduced mobility. Walking speed was measured from a timed walk along an unobstructed pathway. Daily step count information was obtained from patients who had enabled step count tracking on their devices. The SMoS of the sample group were compared to expected population values calculated from the literature using 2-tailed Z tests. Results: There were significantly reduced SMoS in patients who presented to the spinal unit than those expected at each age group for both genders, except for the 50-59 age bracket where no statistically significant reduction was observed. Even lower scores were present in those that went on to have surgical management. There was significant correlation of SMoS scores with subjective disability scores such as the Oswetry Disability Index (ODI) and Visual Analogue Scale (VAS) in this cohort. Conclusion: The SMoS is a simple and effective scoring tool which is demonstrably altered in spinal patients across age and gender brackets and correlates well with subjective disability scores. The SMoS has potential to be used as a screening tool in primary and specialised care settings.

1617

P044: Objectifying Clinical Gait Assessment: Comprehensively Describing the Gait Changes That Occur in Spinal Stenosis Patients Using a Simple and Objective Method of Clinical Gait Assessment

Callum Betteridge ^1,2,3,4 , Ralph Mobbs ^1,2,3,4 , Daniel Ho ^1,2,3,4 , and Luke Sy ^3,4,5

¹ University of New South Wales, Faculty of Medicine, Sydney, Australia

² NeuroSpine Clinic, Sydney, Australia

³ NeuroSpine Surgery Research Group (NSURG), Sydney, Australia

⁴ Wearables and Gait Assessment Group (WAGAR), Sydney, Australia

⁵ University of New South Wales, School of Biomechanics, Sydney, Australia

Introduction: Wearable accelerometer-containing devices, known as inertial measurement units (IMUs) have become a mainstay in clinical studies which measure walking features like speed, symmetry, balance and gait smoothness. IMUs have proven accurate, reliable and easy to use in various elderly and neurological populations, but no IMU has been validated in a population of people with spinal disorders. One common use of IMUs in clinical studies is development of a ‘gait profile’—a summary of the typical gait changes expected in certain diseases. Some well-known gait profiles are the shuffling gait of Parkinson’s disease, or the Duchenne limp of hip osteoarthritis. These gait profiles are used by clinicians to diagnose conditions, as well as monitor and prognosticate the disease course. We use the first wearable sensor to be validated in a spinal population, the MetaMotionC (MMC), to measure the gait features of patients with spinal stenosis in a clinical setting. This data is used to create an easy to understand gait profile of spinal stenosis which summarises the gait changes that occur in spinal stenosis across all domains of walking kinematics. Material and Methods: We conduct a cross-sectional observational study comparing the walking patterns of 33 consecutive spinal stenosis patients attending a single neurosurgery clinic with 40 healthy controls. Gait was measured by the MMC during a single, unobstructed walking bout of a self-selected distance between 10-200 m to determine the following gait metrics: gait speed, gait speed variability, step time, step time asymmetry, stride time, stride time variability, step length, step length asymmetry, stride length, stride length asymmetry, dynamic postural stability and cadence. The two cohorts were compared using two-sided Welch’s t-tests for all relevant gait metrics. Results: All gait metrics were significantly altered in the spinal stenosis cohort, suggesting a global decline in all walking features. However, certain metrics were more significantly altered than others, resulting in a varied gait profile unique to spinal stenosis. Overall, spinal stenosis patients walked with 10% lower cadence, 13% higher step and stride time, 20% lower step and stride length, 27% slower speed, 68% higher step length asymmetry, 198% higher step time asymmetry, 61% higher gait speed variability, 68% higher stride length variability, 81% higher step time asymmetry, and 80% higher dynamic postural instability. Conclusion: The MMC/IMUPY system is a simple, accurate and reliable system for clinical gait analysis, and should be used for assessment of spinal stenosis by comparing a patient’s gait profile to the gait profile presented in this study.

1620

P045: Proposed Measure of Dynamic Instability: The Walking Orientation Randomness Metric: WORM Score: A Promising Indicator of Falls Risk in Spinal Stenosis Patients

Callum Betteridge^1,2,3,4, Ralph Mobbs^1,2,3,4, and Luke Sy^3,4,5

¹ University of New South Wales, Faculty of Medicine, Sydney, Australia

² NeuroSpine Surgery Research Group (NSURG), Sydney, Australia

³ NeuroSpine Clinic, Sydney, Australia

⁴ Wearables and Gait Assessment Group (WAGAR), Sydney, Australia

⁵ University of New South Wales, School of Biomechanics, Sydney, Australia

Introduction: Like previous innovations which provided an objective insight to clinicians for prognostic and diagnostic decision making, wearable sensors provide a similar objectivity to gait analysis for the neurological and musculoskeletal pathologies affecting gait. The clinical benefit is evident, with the ability to objectively classify gait for diagnostic means, identify deterioration of gait for prognostication, assess frailty in the elderly, examine pre- and post-intervention performance, or predict potential falls without having to leave the clinic. One key variable that has been extensively studied in the literature is postural control, also known as dynamic balance. In the past, literature has defined this by movements of the center of mass (CoM) in the anteroposterior (AP) and mediolateral (ML) directions, with various calculations used to score the severity of any abnormal movements. We propose a novel measure, the Walking Orientation Randomness Metric (WORM score) which considers aberrant movement of the CoM in both AP and ML directions simultaneously and is independent of the length of stride. Material and Methods: We conduct a cross-sectional observational study which examined the walking patterns of 33 consecutive spinal stenosis patients (9 fallers, 24 non-fallers) attending a single neurosurgery clinic in 2020. The WORM score was defined as either the length of the path taken by the CoM (WORM 1) or the area of the shape made by the path (WORM 2) or the convex perimeter of the shape made by the path (WORM 3) relative to the base of support per meter of walking, and was measured by a single wearable sensor, the MetaMotionC device, attached to the skin immediately superior to the sternal angle. The WORM scores of fallers and non-fallers were compared using two-sided Welch’s t-tests, as were the WORM scores of spinal stenosis patients with 40 healthy controls. Additionally, the sensitivity, specificity, positive likelihood ratio (PLR) and negative likelihood ratio (NLR) of the WORM scores’ abilities to correctly classify patients as fallers and non-fallers were tested. Results: WORM 1 was.280m in healthy controls, .282 m in the non-faller cohort and 1.102m in the faller cohort. WORM 2 was.001 m² in healthy controls,.001m² in the non-faller cohort and.014 m² in the faller cohort. WORM 3 was .004 m in healthy controls, .002 m in the non-faller cohort and.032 m in the faller cohort. WORM 1 and 3 differentiated the groups with a sensitivity of 89%, specificity of 83%, PLR of 5.33 and NLR of .13. WORM 2 differentiated the groups with a sensitivity of 78%, specificity of 79%, PLR of 3.73 and NLR of .28. Conclusion: The WORM score displays remarkable success in differentiating fallers and non-fallers from amongst a cohort of spinal stenosis patients, lending credence to its ability to measure changes to dynamic stability. Furthermore, WORM 1 and WORM 3 seem to be able to identify the postural changes in spinal stenosis, but WORM 3 also appears to be more significantly altered amongst fallers from this cohort, suggesting it has both diagnostic and prognostic utility.

1631

P046: Cervical Interbody Biometrics in Maldivian Population and Relevance to Implant Design and Selection

Juan Lourido ¹ and Juman Rasheed ²

¹ Tree Top Hospital, Neurosurgery, Hulhumale, Maldives

² Tree Top Hospital, Medicine, Hulhumale, Maldives

Introduction: For the last three decades, custom autograft bone used for interbody fusion in cervical surgery has been replaced in most settings in the world by different cages and products. With the exception of some systems such as 3D printed metal implants, the most widely used implants in the interbody space in cervical surgery are available in limited, standardized sizes with little difference among different companies. This is even more relevant regarding arthroplasty devices, where the smallest sizes are larger than cervical cages. Local populations in relatively isolated areas such as the Maldives, may present with average biometrics that are significantly different from other areas of the world. Material and Methods: 450 consecutive cervical MRI of patients are analyzed using computer software at the Radiology Department Station. AP and Lateral measurements of the endplates at cervical levels C5, C6 and C7 are noted, as well as the diameter of the largest inscribed circumference in the surface. Height of discs are measured, noting the ratio target disc/adjacent disc in the cases indicated for surgery. Interbody implants available in the country as well as from leading companies of the industry are noted for height, AP and lateral sizes and surface, smallest, largest, and average. Results: Descriptive biometrics of the cervical interbody area relevant to interbody fusion or arthroplasty in the Maldivian population (local demographics are presented). Relation of local biometrics to average devices commonly available. Conclusion: Careful selection of the cervical interbody implants must be kept in mind, as not all those commercially available, even in different sizes, will be adequate for the patients in this population. This study raises the question of comparability of results regarding biomechanical behaviour or fusion with other populations, as the ratio implant size/vertebral surface as well as other parameters differs.

1693

P047: Biomechanical Analysis of Structural Stability of the Lumbar Spine Following the Extent of Endoscopic Lumbar Foraminotomy: A Finite Element Study

Jeong Hyeon Lee ¹ , Sung-Jae Lee ¹ , Dong Min Son ¹ , Eghan-Acquah Emmanuel ¹ , and Jin-Sung Luke Kim ²

¹ Inje University, Department of Biomedical Engineering, Gimhae, South Korea

² Seoul St. Mary’s Hospital, Department of Neurosurgery, Seoul, South Korea

Introduction: For the decompression of narrow lumbar foramen, a part of the facet joint should be removed properly. This surgical decompression alleviates the radiating leg pain or improves the intermittent neurogenic claudication. However, this surgical procedure has a negative impact on spinal stability according to the amount of the facet joint. Recently, endoscopic lumbar foraminotomy, which secures space for the spinal nerve to pass through partial facet joint removal, attracts much attention. However, research on the stability of the vertebral body related to this is insufficient. Therefore, this study aimed to analyze the biomechanical structural stability by analyzing the mobility of the surgical segment (range of motion, ROM) and the changes in stress distribution at the facet joint and disc followingthe extent of facet joint removal using finite element analysis. Material and Methods: A previously validated 3-dimensional finite element model of the lumbar (L1-L5) segment of a normal person was used in this study. Three types of post-op models were constructed following the extent of L4 superior facet joint removal and surgical approach direction (Type 1: intact pre-op model, Type 2: foraminotomy of left-superior corner of the facet, Type 3: extended foraminotomy removing right-superior corner and the center of the facet, Type 4: total facetectomy). The inferior endplate of S1 was completely fixed, a 10Nm pure moment of flexion, extension, axial rotation, and lateral bending was applied at the superior endplate of L1 with a follower load of 400N. The structural stability of the vertebral body following the extent of facet joint removal was analyzed by confirming the relative increase rate of the ROM and stress distribution of the surgical segment after each type of surgery compared to pre-op (Type 1). Results: In all loading conditions, the increase rate of the ROM and peak von Mises stress was highest in Type 4 (25-53%) compared to Type 1. The ROM increase rate post-op compared to pre-op was the highest in left axial rotation (Type 2: 4%, Type 3: 5%, Type 4: 53%). And under other loading types, in Type 2, Type 3 and Type 4 were within 1%, 1%, and 35%, respectively. The differences between Type 2 and Type 3 were negligible although Type 3 showed slightly higher. Thus, there was no significant difference in ROM according to the extent facet removal. The rate of peak von Mises stresses were highest in axial rotation (left, right) and left lateral bending at the facet joint (Type 2: 18%, Type 3: 18%, Type 4: 38%). This trend was similar in the disc (Type 2: 19%; Type 3: 19%; Type 4: 40%, axial rotation). The increase was relatively slightly lower under other loading conditions. Conclusion: In symptomatic lumbar foraminal stenosis, the impact of endoscopic foraminotomy on the stability may be less than those of total facetectomy. There is no significant difference between the standard and extended endoscopic foraminotomy on stability of the lumbar spine.

1891

P048: A Validated State of the Art Human Spine Finite Element Model for Accurate Biomechanical Simulations

Ibrahim El Bojairami ¹ , Khaled El-Monajjed ¹ , and Mark Driscoll ¹

¹ McGill University, Mechanical Engineering, Montreal, Canada

Introduction: Numerous spine Finite Element (FE) models have been developed to analyze spine loadings, injuries, mechanical tolerances, and low-back pain. Although such models provide huge clinical insights, the simplifications involved of eliminating the significant contribution of torso soft tissues, the thoracolumbar fascia (TLF), accurate muscles representation, intramuscular pressure (IMP), and intra-abdominal pressure (IAP), hinder the results and conclusions made therefrom. Thus, the purpose, and major contribution of this research was to develop a detailed, 3-dimensional and comprehensive FE model of the spine integrating all major torso effects, mainly IMP, IAP, and TLF as an accurate, on-the-fly, clinical assessment tool. Materials and Methods: Muscles and IAP were modelled as fluid filled pressurized structures, as previously shown to be valid [8] in human tissue FE modelling. TLF, tendons, vertebral bodies (VBs), and intervertebral discs (IVDs) were modelled as flexible bodies. All parts were modelled from MRI-scanned human body parts, accounting for a total of 273 modelled objects. A common problem in FE is the trade-off between accuracy and computational feasibility. To maintain accuracy to an excellent level, a novel new meshing technique has been also proposed whereby contacts between adjacent volumes replaced with confirming mesh. Due to the high complexity of the model, considerable validation was performed. Firstly, applying forward angular displacement, moment around L5-S1 and the pressure in the IVDs were compared to published studies. Further, applying forward flexion, the displacements of the VBs T10-L5 in the sagittal plane were also compared to literature results. Lastly, inputting EMG documented muscle forces [12] representative of the 20 Kg lifted load, back muscles IMP was compared to IAP. Results: Upon applying the recorded angular displacement, the lumbar spine showed an increasing moment from 5.5 to 9.3 N.m. Furthermore, Dreischarf et. al. reported an average moment of 7.5 N.m at 34^o, where the model predicted this moment at 33^o. IVDs pressure increased from .41 to .66 MPa which closely resembled physiological ranges when compared to published results. Furthermore, the vertical displacements of the VBs in the sagittal plane, under forward flexion, showed a 6% maximum discrepancy when compared to documented data, at T11. Finally, activating the muscles with a force representative of the 20 Kg load in Mueller et. al, the model predicted a 17.89 mmHg IAP and a total of 103.98 mmHg IMP, which reliably fell in the vicinity of documented measured values, with an approximately 13% discrepancy. Conclusion: The developed novel model is state of the art as it includes most physiological tissues known to contribute to spinal loading. It was indirectly validated against numerous published studies. Further, the authors’ efforts to reduce computation time, mesh quality and conforming volumes, makes for an optimum model with which to conduct future studies. Given the model’s accuracy, it potentially serves as a great, fast, and reliable clinical tool to assess various spine injuries and conditions in under 3 minutes.

Deformity-Cervical

164

P049: The Benefit of Surgery Over Conservative Treatment in Diffuse Idiopathic Skeletal Hyperostosis (DISH). A Systematic Review and Individual Patient Data Meta-Analysis

Michal Krakowiak ¹ , Tomasz Szmuda ¹ , Daniel Ręcławowicz ¹ , Mirosław Stempniewicz ¹ , Shan Ali ² , Jarosław Dzierżanowski ¹ , and Paweł Słoniewski ¹

¹ Medical University of Gdansk, Neurosurgery Department, Gdansk, Poland,

² Medical University of Gdansk, Scientific Circle of Neurology and Neurosurgery, Gdansk, Poland

Introduction: Forestier's disease, also known as diffuse idiopathic skeletal hyperostosis (DISH), is an enthesopathy characterized by calcification and ossification of the spine’s pre-vertebral ligaments. Excessive osteophyte growth in the cervical region may lead to compression of the oesophagus, trachea and laryngeal structures causing dysphagia or airway obstruction. Our study evaluated the factors influencing surgical outcome and complications. We considered the extent of osteophyte excision required to achieve satisfactory results. Material and Methods: A systematic review of DISH cases causing swallowing difficulties and/or respiratory disorders from Jan 2009 to Jan 2020 was conducted. The PRISMA IPD protocol was used and literature from the following database was extracted: Google Scholar, Cochrane Database, PubMed, EBSCO Medline and EMBASE (Ovid). The following languages were included: English, Spanish, German, Turkish, Romanian, Chinese, Korean and Norwegian. Cases with the following findings were excluded: pharyngeal/laryngeal structure pathology or tumor, cervical trauma, spine or laryngeal surgery, acute infection, neuromuscular diseases which could cause respiratory distress and/or dysphagia. Factors included into the analysis included the: patient’s age, symptom severity and duration, comorbidities, treatment, complications, operative approach, the spinal level of compression and the levels affected. Preoperative and postoperative X-rays using GNU Image Manipulation Program (version 2.10.14) were resized, superimposed and compared. The extent of excision was measured by pixel count with ImageJ (version 1.8.0_112). All events during the 30-day follow-up were considered as posttreatment complications. Results: 1033 unique publications were screened for eligibility and a total of 135 publications were included (of which 121 were individual clinical case reports and 14 were case series).The authors did not have access to 13 papers . 151 patients were treated surgically. Osteophytectomy (OP) was the most common treatment n = 110 (72.8%), 12 patients (7.95%) qualified for corpectomy procedures and 20 patients (13.2%) received an anterior cervical discectomy and fusion (ACDF). 19 (13%) complications were described. Surgical treatment resulted in a complete relief of symptoms in 67% of cases, whereas, 94% of conservatively treated patients remained symptomatic (P < .05). Patients suffering from a limited range of motion (ROM) achieved a worse surgical outcome (68% vs 47%) (P = .018). Compression at the C3-C4 level correlated with a worse surgical outcome (59.55 vs 42.67%, P = .02). The final surgical outcome did not correlate with the procedure type, the extent of osteophyte resection, sex, comorbidities, weight loss and the severity of symptoms. A negative correlation was found between the age, number of affected levels and the extent of resection (P = .033 and P = .031). A greater extent of osteophyte resection resulted in less postoperative complications (P = .02). Surgical complications did not correlate with: sex, comorbidities, obesity, preoperative weight loss, affected levels or with a limited range of motion (P > .05). Conclusion: Surgery is a relatively safe and effective treatment method in Forestier disease compared to conservative treatment. Spine surgeons prefer an anterior approach when resecting osteophyte-associated dysphagia and/or airway obstruction. While surgical treatment is effective, physicians should remain cognizant of the factors influencing surgical complications in order to potentially reduce them.

521

P050: Radiographic Outcomes Following Circumferential Cervical Fusion

Andrew Platt ¹ , Bledi C. Brahimaj ² , Brian T. David ² , and Vincent C. Traynelis ²

¹ University of Chicago, Chicago, USA

² Rush University Medical Center, Chicago, USA

Introduction: Circumferential fusion is one of the many strategies that can be employed to treat patients with cervical spondylotic myelopathy who have failed non-operative management. This study includes a retrospective case series and analysis of radiographic outcomes following circumferential cervical fusion. Material and Methods: A retrospective analysis was performed of patients who underwent single-stage anterior-posterior or posterior-anterior-posterior cervical spine fusion performed by a single surgeon at an academic medical center between 2009 and 2016. Patients who underwent staged procedures or who did not undergo both anterior and posterior fixation were excluded. Primary outcome measures included radiographic outcomes including C2-7 sagittal vertical axis (SVA), cervical lordosis (CL) from C1 to C7 and from C2 to C7, and T1 slope (T1S). Radiographic measurements were assessed preoperatively as well as at the first and last postoperative visit. Results: Seventy-two patients (29 male and 43 female, mean age 57.6 years) underwent circumferential cervical fusion. The mean number of instrumented levels was 6.4 ± 1.2. The first postoperative radiographic assessment occurred at a mean 59.1 ± 45.2 days postoperatively and the last radiographic assessment occurred at a mean 535.4 ± 615.6 days postoperatively. SVA increased from 38.4 ± 22.7 mm preoperatively to 42.6 ± 18.6mm at the first postoperative visit and to 46.6 ± 18.8mm at the final postoperative visit. The increase from the first postoperative visit to the final postoperative visit (P = .006) and the increase from the preoperative visit to the final postoperative visit (P = .001) were both statistically significant. C2-7 cervical lordosis increased from -3.7 ± 17.7 degrees at the preoperative visit to 13.8 ± 12.7 degrees and 13.9 ± 9.9 degrees at the first and last postoperative visits respectively. The increase from preoperative to the first postoperative visit (P < .001) and from preoperative to the final postoperative visit (P < .001) were both statistically significant. The same trend was also noted for C1-7 lordosis. T1 slope increased from 24.3 ± 10.0 degrees at the preoperative visit to 30.2 ± 10.5 degrees and 32.4 ± 11.0 degrees at the first and last postoperative visits respectively. The increase from preoperative to the first postoperative visit (P < .001) and from preoperative to the final postoperative visit (P < .001) were both statistically significant as well as the increase in T1 slope between the first and final postoperative visit(P = .034). The T1 slope/cervical lordosis(c2-7) mismatch decreased from 28.0 ± 15.9 degrees at the preoperative visit to 16.4 ± 10.7 degrees at the first postoperative visit, however, then increased to 18.5 ± 11.4 degrees at the final postoperative visit. The decrease from preoperative to the first postoperative visit (P < .001) and from preoperative to the final postoperative visit (P < .001) were both statistically significant. Conclusion: Few studies have analyzed radiographic outcomes following circumferential cervical fusion. This study, of 72 patients followed for an average of 535 days postoperatively showed that although both C1-7 cervical lordosis and C2-7 cervical lordosis increased postoperatively, there was a corresponding increase in C2-7 SVA and T1 slope. Furthermore, the T1 slope and SVA were the only two metrics to significantly change between the first and last postoperative examination. Further research is necessary to assess how the above metrics affect patient reported outcomes and the rate of reoperation.

805

P051: Ehlers Danlos Syndrome Associated Craniocervical Instability with Cervico-Medullary Syndrome

Alex Spiessberger ¹ , Nicholas Dietz ² , Basil Grüter ² , and Justin Virojanapa ¹

¹ Northwell Health, Orthopedics, New York, USA

² University of Louisville, Louisville, USA

Study Design: Retrospective cohort. Objective: Ehlers Danlos syndrome predisposes to craniocervical instability with resulting cranial settling and cervicomedullary syndrome due to ligamentous laxity. We investigate differences in radiographic outcomes and complications between two surgical techniques in patients with EDS and CCI: occipital bone versus occipital condyle fixation. Methods: A retrospective search of the institutional operative database between 07/01/2017 and 12/31/2019 was conducted to identify EDS patients who underwent CCF with either occipital bone (Group OB) or occipital condyle (Group OC) fixation. Pre- and postoperative radiographic measurements and operative complications were compared. Results: Of a total of 26 patients, 13 received OC and 13 received OB fixation. 85% of the patients underwent OC underwent fusion from occiput to C2 while the remaining 15% had fusion from occiput to C3. Preoperative measurements were similar between OC and OB groups. Postoperative change for CXA was +14.4° (8.8, 0-30) in OC versus 16.2 (12.4, -4-38) in OB, P .43; change of pB-C2 was -2.6mm (1.8,-5.3-0) for OC versus -1.2 (4, -4.6-8), P .26 in OB; postoperative C2C7 sagittal cobb angle was -2.6 (19.5, −43-39) for OC versus -2.6 (11.4, -21-12) in OB. Operative complications were seen in 1 out of 13 patients (8%) versus 2 out of 13 patients (16%), P = 1. Conclusion: In EDS patients with CCI undergoing CCF, radiographic and clinical outcome were similar between those with OC versus OB fixation. Both techniques resulted in sufficient correction of pB-C2 and CXA measurements with low complication rate.

1612

P052: The value and significance of pre-correction with cervical spine traction in the treatment of severe cervical kyphosis

Yu Sun ¹

¹ Institute of Spine Surgery, Peking University Third Hospital, Department of Orthopaedic Surgery, Beijing, China

Objective: To reveal the value and significance of pre-correction with cervical spine traction in the treatment of severe cervical spine kyphosis by means of retrospective analysis of surgical results. Methods: Retrospective study of patients with severe cervical spine kyphosis (Cobb>40 degrees) who were treated in our hospital from March 2003 to March 2017. In this series, 32 cases with 24 males and 8 females, who were 19.5 ± 12.2 years old averagely, were included. According to whether getting cervical traction prior to correction surgery or not, the cases were divided into two groups, traction group and no traction group. There were 26 cases in traction group. In those, 4 cases received skull traction and 22 cases received cervical suspended traction before final surgical correction. Six cases had surgical releasing prior to traction. There were six cases in the no- traction group. The kyphotic angle of cervical spine before and after traction and after surgical correction was recorded. The JOA (Japanese Orthopedic Association) score in different period was recorded. Results: In this series, the average kyphotic Cobb angle was 73.5 ± 26.5 and 16.6° ± 17.16° (P < .01) before and after the surgical correction, respectively. The final correction rate was 79.8 ± 19%. The JOA score improved from 11.9 ± 4.5 to 15.2 ± 2.90 (P < .01). The kyphotic Cobb angle in traction group (77.9° ± 26.5°) was much worse than it in no traction group (54.7° ± 18.2°) (P < .05) before treatment. But the final surgical correction in traction group (81.7 ± 17.9%) was better than it in no traction group (73.4 ± 25.8%). The pre-correction rate (70.30 ± 18.7%) and final surgical correction rate (83.8 ± 14.4%) in patients having suspended traction were higher than those (52.2 ± 21.8% and 70.4 ± 32.1%) having skull traction. Conclusions: The pre-correction by cervical spine traction and final surgical correction by anterior, posterior or combined approaches of Internal Fixation and fusion can achieve good results for severe cervical spine kyphosis. Suspended traction can provide better pre-correction effect.

1648

P053: The Application of 3D Printed Customized Artificial Cage in the Treatment of Cervical Scoliosis

Yu Sun ¹

¹ Institute of Spine Surgery, Peking University Third Hospital, Department of Orthopaedic Surgery, Beijing, China

Objective: To explore the effect, safety and feasibility of application of 3D printed customized artificial cage, in the surgical treatment of patients with cervical scoliosis. Methods: Patients with congenital cervical scoliosis underwent distraction technique of concave side between May 2017 and January 2020 were included. The patients were separated into two groups according to the type of cage they use. We collected the clinical data and perioperative complications. We compared the curative effects and complications to see if there is any statistical difference between the two groups. Results: 15 patients were included in this research, 11 were male and 4 were female. The age of the patients were between 6 and 17 years old, average 9.67 ± 3.54 years old. The mean follow-up time is 9.53 ± 9.01 months. There were 7 patients in 3D printed group, 8 patients in control group. The correction rate the both group are 64.45%. In 3D printed group, 3 patients developed nerve root dysfunction after surgery, in 1 patient, a revision surgery for screw adjustment is needed, and recovered after revision surgery, the other 2 patients recovered spontaneously. In control group, 2 patients developed nerve root deficit after surgery, both recovered spontaneously. 3 patients had fever after surgery. 2 patients had delayed healing of wound of bone harvest site. 1 patient had persist pain at bone harvest side. For the occurrence of complications, there isn’t any significance between the two groups. Conclusion: The application of 3D printed customized artificial cage in the treatment of cervical scoliosis is with good feasibility and clinical safety. Short-term follow-up showed excellent result with a promising future.

1738

P054: C1-C2 Coronal and Sagittal Angle Based Treatment Algorithm for Need of Transoral Odointectomy in Complex Craniovertebral Junction Anomalies with Clinico-Radiological Outcomes Analysis

Rakesh Kumar ¹ and Deepak Kumar Singh ²

¹ Royal Hospital for Sick Children, Scottish National Spinal Deformity Service, Edinburgh, United Kingdom

² Dr Ram Manohar Lohia Institute of Medical Sciences, Neurosurgery, Lucknow, India

Introduction: Craniovertebral junction (CVJ) pathology by virtue of its complexity is a surgical challenge in realm of neurosurgery and in most of the complex CVJ cases there are dilemma regarding the need of anterior approach in form of trans oral odointectomy (TOO). We analysed the clinical and radiological outcome of 58 patients with CVJ anomalies treated surgically with consideration of C1-C2 joint coronal and sagittal angle and a surgical approach protocol is proposed. Material and Methods: A Prospective study over period of 2 years included 58 newly diagnosed patients with symptomatic craniovertebral junction anomalies, congenital atalantoaxial dislocation (AAD), basilar invagination (BI) or traumatic fractures of atlas or axis vertebrae were included in study after obtaining written informed consent. Patients evaluated clinically, investigated and operated with reduction and rigid internal fixation with screws and rod. Clinical outcome measured by Modified Japanese orthopedic association score(mJOA) and radiologically by conventional craniometrics indices. Paired ‘t’ test used for statistical analysis. Results: Mean age of patients was 30 years, with mean follow up: 8.5 months. 46(80%) patients operated by posterior and 12(20%) by combined approach (anterior trans oral with posterior). Occipitocervical fixation was done in 15(25.8%) cases and C1-C2 fixation in 43(74.2%) cases. As compared to patients with low coronal angle, the patient with coronal angle >65⁰ needed anterior decompression (87.5%) and all (100%) had Occipitocervical fixation. Clinical outcome analysis showed significant improvement in mean mJOA score (preop 11.9 Vs postop 14.6) after surgery. All craniometrics indices were significantly improved after surgery. Overall complication rate was 10% with mortality of 1.7%. 6 months follow up completed in 86% patients with 100% fusion rate. Conclusion: This study explores bony and vascular anatomical factors of CVJ anomalies which are important in deciding treatment. Assimilation of atlas is most commonly encountered anomaly in CVJ disorders (60% in our study) and it’s not absolute contraindication for putting C1 lateral mass screws as shown in this study. High C1-C2 joint CA >65° is usually associated with significant condylar and C1 lateral mass hypoplasia and requires occipitocervical fixation. In contrast to many recent studies, there is role of anterior trans oral decompression in few cases of irreducible AAD with or without BI in patients having high C1-C2 joint coronal and sagittal angle. Based on these simple C1-C2 joint coronal and sagittal angle measurements we are proposing management algorithm for CVJ anomalies which comply with proper bony realignment and adequate decompression.

1932

P055: The Modification of Appropriateness Criteria for a Cervical Deformity Corrective Surgery

Peter Passias ¹ , Katherine Pierce ¹ , Nicholas Kummer ¹ , Lara Passfall ¹ , Oscar Krol ¹ , Waleed Ahmad ¹ , Sara Naessig ¹ , Aaron Buckland ¹ , Themistocles Protopsaltis ¹ , Bassel Diebo ² , Renaud Lafage ³ , and Virginie Lafage ³

¹ NYU Langone Orthopedic Hospital; New York Spine Institute, Departments of Orthopedic and Neurologic Surgery, New York, USA

² SUNY Downstate, Department of Orthopedics, Brooklyn, USA

³ Hospital for Special Surgery, Department of Orthopedic Surgery, New York, USA

Introduction: The Scoliosis Research Society established Appropriateness criteria for surgery for degenerative lumbar scoliosis (DLS) in order to improve and unify clinical decision making. Though utilized and validated in various cohorts, an appropriateness criteria has yet to be developed in a cervical deformity (CD) population. Material and Methods: CD patients > 18yrs were included. Each patient was scored based upon the SRS-appropriateness criteria, comprised of clinical or radiographic characteristics and was modified for a cervical deformity cohort: (1) Severity of Symptoms[NDI], (2) Severity of Myelopathy [mJOA.], (3) Progression of Deformity, (4) Global Sagittal Malalignment[Schwab modifiers], (5)Severity of Risk Factors, (6) Degree of the T1S-CL curvature. For the category ‘progression’, radiographs were only available at one preoperative time point, and we were unable to include this in the total score. Based upon certain combinations of criteria, patients were stratified into More Appropriate (MA) and Less Appropriate (LA). Results: 100 patients included (61 years, 62%F, 29.5 kg/m²). Assessment of the categories of Appropriateness of CD surgery: (1) Symptoms: 6% None to Mild, 94% Moderate to Severe; (2) Myelopathy: 16% None to Mild, 45% Moderate, 39% Severe; (3) All were grouped No Progression in the present study; (4) 19% demonstrated Global Malalignment(+/++Schwab), 81% did not; (5) Risk Factors: 27% had None to Mild, 63% Moderate, 10% Severe; (6)Curvature TS-CL demonstrated 88.6% of patients Severe(>20°).Patients were stratified into Less Appropriate (LA) and More Appropriate (MA) categories based upon the DLS study. LA in each of the surgical risk cohorts: None to Mild (NDI <28), with (1) None to Moderate myelopathy (mJOA > 12) and Severe Risk Factors (2) None to Mild myelopathy (15-18) and No Progression or Imbalance (3)Moderate myelopathy (mJOA 12-15) and None to Moderate Risk Factors and no Progression, or imbalance and TSCL < 25 degrees. MA: Moderate to Severe Symptoms (NDI ≥ 30), with (1) Severe myelopathy (mJOA < 12) and Any Risk Factors (2) Moderate myelopathy and None to Moderate Risk Factors (3) Moderate myelopathy with Severe Risk Factors, Progression AND Imbalance (4) None to Mild myelopathy and None to Moderate Risk Factors and Progression OR imbalance (5) None to Mild myelopathy with None to Moderate Risk Factors and TSCL >25 degrees. In the present cohort, 94% were deemed More Appropriate for surgery, 6% Less Appropriate. LA patients demonstrated higher rates of postop dysphagia complications (17% vs 2%), met MCID for NDI less (0% vs 30.9%), and had more occurrences of DJK (16.7% vs 6.4%) by 2-years, P < .05. Conclusion: In light of the heterogeneity and uncertainty surrounding CD, this study developed CD appropriateness criteria, using established methodology, for surgeons to consider in the preoperative decision-making that correlate well with major post-op occurrences. Application of the appropriateness criteria for CD may optimize patient selection and reduce the incidence of unwarranted surgery, although future validation is necessary.

1958

P056: Defining Symptomatic vs Radiographic Distal Junctional Kyphosis After Cervical Deformity-Corrective Surgery

Peter Passias ¹ , Haddy Alas ¹ , Renaud Lafage ² , Daniel Sciubba ³ , Breton Line ⁴ , Sara Naessig ¹ , Lara Passfall ¹ , Oscar Krol ¹ , Nicholas Kummer ¹ , Eric Klineberg ⁵ , D. Kojo Hamilton ⁶ , Virginie Lafage ² , Douglas Burton ⁷ , Shay Bess ⁴ , Jeffrey Gum ⁸ , Waleed Ahmad ¹ , Katherine Pierce ¹ , Avery Brown ¹ , Alan Daniels ⁹ , Han Jo Kim ² , Themistocles Protopsaltis ¹ , Christopher Shaffrey ¹⁰ , Frank Schwab ² , and Christopher Ames ¹¹

¹ NYU Langone Orthopaedic Hospital, Department of Orthopaedics, New York, USA

² Hospital for Special Surgery, Orthopaedics, New York, USA

³ Johns Hopkins University School of Medicine, Neurosurgery, Baltimore, USA

⁴ Denver International Spine Center, Spine Surgery, Denver, USA

⁵ University of California, Davis, Davis, USA

⁶ University of Pittsburgh, Pittsburgh, USA

⁷ University of Kansas Medical Center, Kansas City, USA

⁸ 8Norton Leatherman Spine Center, Louisville, USA

⁹ Warren Alpert School of Medicine, Brown University, Providence, USA

¹⁰ University of Virginia Medical Center, Neurosurgery, Charlottesville, USA

¹¹ UCSF, Orthopaedic Surgery, San Francisco, USA

Objective: Distal junctional kyphosis (DJK) is a relatively new surgical concept often defined in the literature as a change in DJK angle < −10°. It remains unclear whether this cut-off carries clinical significance in terms of patient quality of life, but may have a significant effect when associated with neurological sequelae or reoperation. The aim of our study was to establish a clinically relevant definition of symptomatic DJK. Methods: Retrospective analysis of operative cervical deformity (CD) patients. DJK angle (DJKA) was defined as >10° change in kyphosis between LIV and LIV-2 in addition to >10° index angle. Pts with DJKA>10° & 1) no reop due to DJK(DJF) and 2) no physician-reported neurological sequelae by 1Y postop were categorized as “Mild DJK.” Those with DJKA>10° in addition to 1) reop due to DJK(DJF) or 2) >1 new-onset neurological sequelae related to DJK were categorized as “Symptomatic DJK”. ANOVA explored differences in PROMs at baseline (BL) up to 1Y postop. Multivariate logistic regression analyzed predictors of inferior HRQLs associated with DJK groups.

Results: 148 CD patients included. 65 pts had no DJK, 25 had Mild DJK and 12 had Symptomatic DJK. By 1Y, 6/12 pts had DJF, 6/12 pts had >1 DJK-related neurologic sequelae not present before surgery without DJF, and 2 pts had both. Symptomatic DJK pts had higher mean DJKA than Mild DJK pts immediately post-op (29.8° vs 19.1°, P = .150). No differences in BL HRQLs were noted between groups (all P > .05). At 1Y, Symptomatic DJK pts had significantly higher NDI (52.3 vs 28.7, P = .006) and trended toward lower EQ5D (.75 vs .81, P = .059), higher NRS Back (5.82 vs 4.06, P = .119), lower VAS (56.4 vs 71.7, P = .084), and lower mJOA (14.2 vs 15.0, P = .495). Controlling for age and gender, conditional forward regression analysis revealed Symptomatic DJK to be a strong predictor of NDI >1 SD above the mean compared to Mild DJK pts (OR: 43.4 [2.8-668.1], P = .007). Conclusions: DJK associated with reoperation and/or neurologic sequelae was associated with inferior HRQL metrics over long-term follow-up. Our results demonstrate that Symptomatic DJK may not necessarily correlate to a greater measured DJK angle per se (i.e. >20°); instead, DJK with concurrent neuro findings or subsequent reoperation better predicts worsened disability compared to DJK alone.

1960

P057: At What Point Should the Thoracolumbar Region Be Addressed in Patients Undergoing Corrective Cervical Deformity Surgery

Peter Passias ¹ , Katherine Pierce ¹ , Sara Naessig ¹ , Waleed Ahmad ¹ , Renaud Lafage ² , Virginie Lafage ² , Eric Klineberg ³ , Bassel Diebo ⁴ , Themistocles Protopsaltis ¹ , D. Kojo Hamilton ⁵ , Shaleen Vira ⁶ , Breton Line ⁷ , Robert Hart ⁸ , Douglas Burton ⁹ , Shay Bess ⁷ , Frank Schwab ¹⁰ , Christopher Shaffrey ¹¹ , Justin Smith ¹¹ , Christopher Ames ¹² , Oscar Krol ¹ , Lara Passfall ¹ , and Nicholas Kummer ¹

¹ NYU Langone Health, Manhattan, USA

² Hospital for Surgery, Manhattan, USA

³ University of California, Davis, USA

⁴ SUNY Downstate Department of Orthopedic Surgery, Brooklyn, USA

⁵ University of Pittsburgh School of Medicine, Pittsburgh, USA

⁶ UT Southwestern, Dallas, USA

⁷ Denver International Spine Center, Denver, USA

⁸ Swedish Neuroscience Institute, Seattle, USA

⁹ University of Kansas Medical Center, Kansas City, USA

¹⁰ Hospital for Special Surgery, Manhattan, USA

¹¹ University of Virginia Medical Center, Charlottesville, USA

¹² University of California, San Francisco, USA

Introduction: Consideration of the distal regional and global alignment is a critical determinant of outcomes in CD surgery. Thoracolumbar malalignment is often seen in patients presenting with cervical deformities. For operative cervical deformity (CD) patients, it is unknown whether certain thoracolumbar parameters play a large role in poor outcomes (complications, DJK, reoperation) and whether addressment of such parameters is warranted. Material and Methods: Included: surgical CD pts(C2-C7 Cobb > 10°, CL > 10°, cSVA > 4cm, or CBVA > 25°) with full baseline and 1-year data. Patients were assessed for ratios of preop cervical and global parameters including: C2 Slope/T1 slope, TS-CL/PI-LL, cSVA/SVA. Deformity classification ratios of cervical (Ames-ISSG) to spinopelvic (SRS-Schwab) were investigated: cSVA modifier/SVA modifier, TS-CL modifier/PI-LL modifier. Cervical to thoracic ratios included C2-C7 lordosis/T4-T12 kyphosis. Correlations assessed the relationship between ratios and poor outcome (major complication, reoperation, HRQL decline or failure to meet MCID). Decision tree analysis through multiple iterations of multivariate regressions) assessed cut-offs for ratios for acquiring suboptimal outcomes. Results: 110 CD pts included (61.5 years, 66%F, 28.8 kg/m²). By approach, 18.2% underwent anterior-only procedures, 46.4% posterior, and 35.4% combined (levels fused: 7.7). The average preoperative radiographic ratios assessed included a C2 slope/T1 slope of 1.56, TS-CL/PI-LL of 11.1, cSVA/SVA of 5.4, CL/TK of .26. Ames-ISSG and SRS-Schwab modifier ratios of cSVA/SVA .1 and TS-CL/PI-LL of .35. Pearson correlations demonstrated a relationship between major complications and the baseline TS-CL/PI-LL, Ames TS-CL/Schwab PI-LL modifiers, and the CL/TK ratios (P < .050). Reoperation had a significant correlation with the TS-CL/PI-LL and the cSVA/SVA ratios. Postoperative DJK had a correlation with the C2 slope/T1 slope and CL/TK ratios. Not meeting MCID for NDI correlated with the CL/TK ratio and not meeting MCID for EQ5D correlated with the Ames TS-CL/Schwab PI-LL. Conclusion: Consideration of cervical to global alignment is a critical determinant of outcomes in cervical deformity corrective surgery. Key ratios of cervical to global alignment correlate with sub-optimal clinical outcomes. A larger cervical lordosis to thoracic kyphosis predicted a complication, DJK, and not meeting MCID for NDI.

Deformity-Thoracolumbar (Adolescent)

35

P058: Neurological Deficit Due to a Combination of Thoracolumbar Kyphosis and Lumbar Canal Stenosis in a 15-Year-Old Boy With Achondroplasia

Ghanshyam Kakadiya ¹ , Kshitij Chaudhary ^1,2 , and Prashant Gedam ¹

¹ Topiwala National Medical College & Nair Hospital, Department of Orthopaedics, Mumbai, India

² Sir H. N. Reliance Foundation Hospital and Research Centre, Department of Spine Surgery, Mumbai, India

Introduction: Thoracolumbar (TL) kyphosis frequently resolves spontaneously in infants with achondroplasia, a few develop progressive kyphosis. Congenital lumbar canal stenosis (LCS) is another known association. We describe a rare presentation of severe neurological deficit due to both severe TL-kyphosis and LCS in achondroplastic child. Case Report: A 15-year-old male child presented with progressive bilateral lower limb weakness over 2-months. He had mixed UMN and LMN on signs such as Babinski sign, hypotonia and absent deep tendon reflexes. He was not able to walk (Frankel-B) and had a high post-void residual urine volume suggestive of detrusor muscle weakness. Rectal tone and voluntary anal sphincteric contraction were normal. Sitting and supine radiographs revealed he had fixed TL-kyphosis of 69-degree with apex was at T12. The MRI showed spinal cord tenting at T11-12 and T12-L1 discs and multilevel congenital central and lateral recess stenosis from L1-L2 to L3-4 (L4 and L5 were sacralized). The patient was operated with posterior vertebral-column-resection at T12-vertebrae level and multilevel laminectomy extending to L4-level. T10-L2 instrumented fusion was done. Patient started showing neurological improvement 3-months after surgery, however, could not pass urine voluntarily. At final follow-up of one year, the child was ambulatory (Frankel-D) with support of a walker and required intermittent self-catheterization. Conclusion: An early diagnosis and a surgery of the TL-kyphosis before the onset of neurological symptoms could have prevented the neurological deficit. We would recommend that patients who are older than 5-years with progressive TL-kyphosis, especially over 50-degrees should get prophylactic surgery to prevent this complication.

66

P059: What is the Optimal Surgical Method for Achieving Correction and Avoiding Neurological Complications in Paediatric High Grade Spondylolisthesis?

Brett Rocos ¹ , Samuel Strantzas ² , Reinhard Zeller ¹ , Stephen Lewis ¹ , Yongyao Tan ¹ , and David Lebel ¹

¹ Hospital for Sick Children, Department of Orthopaedic Surgery, Toronto, Canada

² Hospital for Sick Children, Department of Neurophysiology, Toronto, Canada

Introduction: Controversy persists in the treatment of high-grade spondylolisthesis (HGS). Surgery is recommended in patients with intrusive symptoms and evidence debates the competing strategies. This study compares the radiological outcomes and post-operative complications at a minimum of 2 years follow up for patients with HGS treated with instrumented fusion with partial reduction (IFIS) with those treated with reduction, decompression and instrumented fusion (RIF). We hypothesise that IFIS leads to a lower rate of complication and revision surgery than RIF. Materials and Methods: A retrospective comparative methodology was used to analyse consecutive high-grade spondylolisthesis treated surgically between 2006 and 2017. Patients diagnosed with ≥ grade 3 spondylolisthesis treated with arthrodesis before the age of 18 years with a minimum of 2 years follow up were included. Patients were excluded if surgery did not aim to achieve arthrodesis or was a revision procedure. Cases were identified through departmental and neurophysiological records. Results: 30 patients met the inclusion criteria. Mean follow-up was 4 years. Ten patients underwent IFIS and the remaining 20 underwent RIF. The two groups showed no difference in demographics, grade of slip, deformity or presenting symptoms. Of 10 treated with IFIS, the SA reduced by a mean of 10° and C7 sagittal vertical line (SVL) changed by 31 mm. In the RIF cohort, SA reduced by 16°and C7 SVL reduced by 26mm. PT was unchanged in both groups. In IFIS cohort 2 patients showed post-operative weakness, resolved by 2 years. None required revision surgery. In the RIF group 4 sustained dural tears and 1 a laminar fracture, 7 showed post-operative weakness or dysaesthesia, 3 of which had not resolved by 2 years. 8 patients underwent unplanned further surgery, 3 for pseudarthrosis. Conclusion: RIF and IFIS show similar radiological outcomes. RIF shows a higher rate of unplanned return to surgery, pseudarthrosis and persisting neurological changes.

79

P060: Congenital Kyphosis: Progressive Correction with an Instrumented Posterior Epiphysiodesis

Brett Rocos ¹ , David Lebel ¹ , and Reinhard Zeller ¹

¹ Hospital for Sick Children, Toronto, Canada

Introduction: Congenital kyphosis is a rare condition. In this case series we sought to identify the outcomes and complications of posterior instrumented fusion and the resultant epiphysiodesis effect in uniplanar congenital kyphosis in patients aged 5 and under. Materials and Method: Patients were included if treated for a uniplanar congenital kyphotic deformity treated with posterior instrumented spinal fusion whilst aged under 5 years between October 2006 and August 2017, with a minimum of 2 years of follow up. Patients were excluded if a coronal deformity greater than 10° was present. Results: Six patients met the inclusion criteria. Mean age at surgery was 3.6 years. The mean kyphotic deformity prior to surgery was 49.7°. All patients underwent posterior instrumented fusion with autogenous iliac crest graft and a cast or brace postoperatively. One patient showed a loss of motor evoked potential on prone positioning which returned to normal on supine positioning. No patient showed any post-operative neurological deficits. One patient was diagnosed with a wound infection which was successfully treated with oral antibiotics. By a follow up of 5.4 years (range 2.2-10.9 years) there was no failure of instrumentation. An epiphysiodesis effect (a difference of ≥ 5° in the kyphotic deformity measured between the immediate post- operative and final follow up lateral whole spine XR) of 16.2° (range 7.2-30.9°) was seen in 5 patients. The mean annual epiphysiodesis effect was 2.7° (95% CI, 1.4-4.1°). No kyphosis proximal to the instrumentation was observed for the duration of follow up. Conclusion: Posterior instrumented fusion and epiphysiodesis is safe and effective. The epiphysiodesis effect occurs in 80% of cases, and the procedure is associated with an acceptable blood loss and a low incidence of neurological complications.

111

P061: Surgical Treatment of High-Grade Spondylolisthesis: Is Interbody Fusion Necessary?

Andriy Mezentsev ¹ , Dmytro Petrenko ² , and Dmytro Demchenko ²

¹ Kharkiv University Clinic, Kharkiv, Ukraine

² Kharkiv University Clinic, Kharkiv, Ukraine

Introduction: Surgical treatment of the high-grade dysplastic spondylolisthesis remains a challenging topic of the contemporary spinal surgery. There is a strong opinion that application of interbody fusion is a standard approach in such patients. Dural tears, radiculopathy and cage subsidence are the main complication of this procedure. Material and Methods: We studied 25 clinical charts of the consecutive high-grade dysplastic spondylolisthesis patients treated in a single clinical center. Three of them had Meyerding 4 and twelve had Meyerding 5. There were 3 males and 12 females in the mean age of 14.6 years (9-28). Follow-up was 5 years. SVA, sacral slope and pelvic tilt were assessed before and after surgery. CT scans performed during follow-up. Results: All patients underwent posterior reduction with temporary intraoperative distraction L1-pelvis and reduction using pedicular screw instrumentation L4-pelvis without laminectomy and interbody fusion. In all patients SVA and pelvic parameters were returned to the near normal values. CT showed posterior fusion, stable reduction and ossification of anterior sacral corner in younger patients. We observed tension neuropathy in 4 older patients that resolved 3 month after the treatment. Conclusion: Intraoperative temporary distraction with pedicular screw instrumentation L4-pelvis allow to normalise sagittal spinal parameters and achieve solid posterior fusion without performing interbody fusion.

145

P062: The Components of Metallosis Generated by Magnetically Controlled Growing Rods and Their Implications

Teng Zhang ¹ , Kam Yim Sze ² , Zhenwu Peng ² , Kenneth Man Chee Cheung ¹ , Yuk Fai Lui ¹ , Yat Wa Wong ¹ , Kenny Yat Hong Kwan ¹ , and Jason Cheung ¹

¹ University of Hong Kong, Orthopaedics and Traumatology, Hong Kong, Hong Kong

² University of Hong Kong, Mechanical Engineering, Hong Kong, Hong Kong

Introduction: It has been a decade since magnetically-controlled growing rods (MCGRs) have been in use for treatment of early onset scoliosis (EOS). Unique complications like metallosis have come to our attention. This manifests as pseudo-capsule formation around the barrel opening (BO) with an accumulation of black/grey particles. The MCGR wear particles’ components and concentrations in human tissues is unclear. This study aims to systematically investigate metallosis to reveal the main metal particle profile of tissues surrounding MCGR and the phagocytic immune response. Material and Methods: All consecutive patients with EOS and MCGRs implanted undergoing rod exchange were recruited between 02/2019 to 01/2020. Two biopsies were taken of the paraspinal muscles surrounding the portion of the barrel housing the magnets (BM) and the BO due to the location of metallosis and its relationship to the MCGR’s distraction mechanism. 5mm³ sized normal tissues 3cm distal to the piston rod were controls. Each biopsy sample was used for spectrum analyses of metal concentrations and histology. Metal concentrations at wear marks and human tissues were studied. The concentrations of metals (mg/kg) in the sample were measured three times by inductively coupled plasma optical emission spectrometers (ICP-OES). For each metal element, the ICP produced excited atoms and ions that emitted electromagnetic radiation at different wavelengths to show the intensity of the emissions. Results: Biopsy samples were collected from 10 patients (average age 12 ± 1.3 years, 80% females). The majority of metals within the piston rod were common Titanium (Ti) alloy with Aluminum (Al), Vanadium (V) and Carbon (C). Six samples were tested and the average concentration (wt/wt) of Ti was 88 ± .6%; Al was 4.9 ± .2%; V was 4 ± 1.0%. In the samples taken at the BO, the concentrations of Ti (54361.34 ± 17467.98 vs control: 301.56 ± 110.39 mg/kg; P = .017) and V (1287.65 ± 407.02 vs control:17.28 ± 4.37 mg/kg; P = .016) were significantly higher than controls and from BM (Ti:24141.55 ± 10585.42mg/kg; P = .028 and V:587.27 ± 271.44 mg/kg; P = .043). For Al, no significant differences in the concentrations were discovered between samples taken at different sites of the implant. A significantly increased concentration of Nd was detected from the samples taken at the BO (34.30 ± 3.94mg/kg; P = .0003) compared to BM (17.03 ± 5.22 mg/kg; P = .024) and to controls (9.50 ± 2.52 mg/kg). Samples were mainly fibromuscular tissues with some atrophic skeletal muscle. Accumulation of black and fine particles was discovered in the dense fibrotic areas. A mild active and moderate chronic inflammatory cell infiltration was seen in the most slides near the black particles. Macrophages containing black pigmentations were observed under high magnification. No observations of local neoplasia were made. Conclusion: This is the first study systematically examining metallosis caused by MCGRs. Vastly increased Ti, V, and Nd concentration with mild to moderate chronic inflammation was found. Ti and V are generated mainly at the barrel openings due to metal-on-metal contact, whereas the Nd from the magnet rotor within the barrel is likely released from the BO during distractions. There is potential toxicity of magnetic metal particles (Nd) in adults with embolisms and liver damage. There may be a concern for child-bearing and teratogenic risks with long-term exposure to these metals.

207

P063: Serum Metal Ion Levels in Adolescent Idiopathic Scoliosis (AIS) Patients 25 Years After Treated with Harrington Rod Instrumentation or Bracing

Simon Sørensen ¹ , Anne Vibeke Schmedes ² , Mikkel Østerheden Andersen ¹ , Leah Carreon ¹ , and Ane Simony ¹

¹ Center for Spine Surgery & Research, Middelfart Hospital, Middelfart, Denmark

² Department of Clinical Biochemistry and Immunology, Sygehus Lillebælt, Kolding, Denmark

Purpose: Surgical instrumentation in children with adolescent idiopathic scoliosis (AIS) is performed early in life and the implants are left in situ for the rest of the patient’s life. Concern has been raised regarding persistent elevated levels of serum metal ions, but only a few studies on the topic have been published. The aim of this study was to compare the levels of serum metal ions in patients with AIS treated with either Harrington Rod Instrumentation or Bracing. Methods: AIS patients treated with Boston brace (BB) or posterior spinal fusion with Harrington rod instrumentation (HR) from 1983 to 1990 were requested to return to clinic. One hundred fifty-nine (73%) of 219 patients were available for follow-up of whom 115 agreed to have a blood draw. Results: The proportion of patients who agreed to have a blood draw were similar in the BB (48 of 100, 48%) and HR (67 of 115, 60%, P = .085) groups. None of the surgical patients had their implants removed. Mean age at follow-up (BB: 43.2yrs vs HR: 43.5yrs, P = .566) and mean length of follow up (BB: 26.5 years vs HR: 24.5 years). Mean Chromium serum levels were similar between the BB (2.71nmol/L) and the HR (2.94nmol/L, P = .827). Mean Cobalt serum levels were also similar between the BB (2.62nmol/L) and the HR (2.75nmol/L, P = .200). Conclusion: Serum metal ions were similar in AIS patients treated with bracing or Harrington Rod instrumentation 25 years after initiation of treatment.

385

P064: Adolescent Idiopathic Kyphoscoliosis—Axial Translational Technique can be a Standard Method

Anowarul Islam ¹

¹ Bangabandhu Sheikh Mujib Medical University, Orthopaedics, Dhaka, Bangladesh

Introduction: Scoliosis is a tri-planner deformity of the spine in sagittal, frontal and coronal planes affects children especially girls during their growth periods. Various systems like axial translation technique has been reported for correction of adolescent idiopathic scoliosis. Material and Methods: 30 patients of idiopathic kyphoscoliosis were treated by Axial Translation Technique with Pedicle Screw and Rod in Bangabandhu Sheikh Mujib Medical University and other private hospitals in Dhaka city from January 2008 to December 2019. The curve correction with more screw on the concave site was assessed, patient satisfaction and correction of cobb angle were measured. Post operative radiological and functional outcome were assessed. Results: All the 30 patients were available for follow-up for minimum 18 months. Most of the cases were female, 20 (66.6%) and 10(33.3%) male patients. The mean age was 14.24 (age range: 10-24 years). There was significant improvement in cobb angle i.e., 32.31% in proximal thoracic, 62.06% in main thoracic and 50.65% in thoracolumbar region which showed correction was more on main thoracic curve and then in thoracolumbar/lumbar curves. Paired t-test showed significant result (P < .001) where correction was maintained until the last follow-up. Conclusion: These results were statistically significant and so it may be concluded that the axial translation technique with more screw in the concave side is ideal technique with good postoperative outcome both clinically and radiologically.

491

P065: Utilisation of Tranexamic Acid in a Patient with Sickle Cell Disease Undergoing Posterior Scoliosis Correction Surgery: Safely Mitigating Bleeding and Vaso-Occlusive Crises

Millie Newall ¹ , Bisola Ajayi ¹ , Thamer Hamdan ¹ , Darren Lui ¹ , and Simon Weil ¹

¹ St. George's University Hospitals NHS Foundation Trust, London, United Kingdom

Introduction: Patients with sickle cell disease (SCD) have high rates of surgical complications including blood loss leading to vaso-occlusive sickle cell crises (VOSCC). These patients require careful peri-operative management including total body transfusions and meticulous haemostasis to optimise surgical outcomes. This is the first case report describing tranexamic use in adolescent idiopathic scoliosis (AIS) surgery and SCD. AIS surgery can be associated with significant morbidity including high volume blood loss. Material and Methods: A 15-year-old female with sickle cell disease was diagnosed with 2 years post menarchal AIS with truncal shift and a large right rib hump which could not be fully reduced with Adams forward bend test with right side bending. She had a history of repeated painful VOSCC, and one admission to ICU for acute chest syndrome at the age of 7-years-old. Her baseline haemoglobin was 80 g/L. A preoperative exchange transfusion reduced the sickle cell haemoglobin from 88 to 24% and increased the total haemoglobin to 109 g/L. A posterior spinal fusion was performed utilising all pedicle screw construction from T3- L1 with TIVA anaesthetic for transcranial spinal cord monitoring. Intraoperative blood loss was reduced by maintaining the mean arterial pressure below 70 mmHg, as well as giving 10 mg/kg intravenous tranexamic acid and opting not to perform a costoplasty despite the presence of a rib hump. Misonix Ultrasonic Bone cutter was used for facetectomies, generous Haemostat Surgiflo in each pedicle instrumented, Spongestan Foam, Surgicel and bone wax were used to provide meticulous haemostasis at osteotomy sites. Two diathermy 2 generators were utilised for simultaneous bipolar and unipolar use. No cell saver was used, and one suctioner was used rather than two. Aggressive IV hydration was utilised to prevent sickle cell crises. Results: Intraoperative blood loss was 300 ml and post-operative recovery was satisfactory but protracted by 4 days of wound ooze, and non-sickle cell pain. She was discharged home eight days post-operatively. Conclusion: This is the first report of tranexamic acid use in a patient with sickle cell disease and adolescent idiopathic scoliosis. This practice was effective in minimizing blood loss and avoiding sickle cell crises. This patient experienced longer than average inpatient stay due to non-sickle cell pain.

612

P066: Thoracic Inlet Measurements as a Measure of Pulmonary Dysfunction in Kyphoscoliotic Deformities: A Prospective Case-Control Study

Vyom Sharma ¹ , Shanmuganathan Rajasekaran ¹ , Dilip Chand Raja Soundararajan ¹ , Ajoy P Shetty ¹ , and Rishi Kanna ¹

¹ Ganga Medical Centre and Hospitals Pvt Ltd, Spine Surgery, Coimbatore, India

Introduction: Pulmonary dysfunction in thoracic kyphoscoliosis has been correlated with chest wall distortion, uneven trunk growth, and restrictive pattern. However, correlation with thoracic inlet dimensions has been reported scarcely in literature. The aim of the study was toanalyse the variation in thoracic inlet measurements on pulmonary dysfunction with varying curve magnitude and thoracic cage parameters. Materials and Methods: In this Nonrandomized, prospective case-control study, after Institutional Review Board (IRB) approval, 80 consecutive patients with thoracic kyphoscoliosis were divided into 3 groups based on Cobb’s angle in degrees; group 1(31–50), group 2(51–80) and group 3(>80) and the following were calculated: a) thoracic inlet measurement by evaluating a Thoracic Inlet Index (TI) on MRI at the sternal level, b) pulmonary function and c) thoracic cage parameters [hemithorax height, rib-apex distance, AP chest diameter at sternal level, transverse thoracic diameter, proximal thoracic kyphosis and number of vertebrae in the curve]. TI values were compared with 20 age-matched asymptomatic controls. Multivariate correlation and regression analysis were performed to investigate the correlation of TI with the severity of the curve, thoracic cage morphology, and pulmonary function. Results: The mean age of the study cohort was 14.1 + 4.4 years and included group-1(6 patients), group-2(55 patients) and group-3(19 patients) versus 12.94 + 2.24 years in controls. Mean TI was 2.86 + .56 in group 1, 3.73 + .9 in group 2, and 4.0 + 1.12 in group 3 versus 2.63 + .43 in controls. Pulmonary dysfunction was severe with TIS > 7.11 (P < .001) in group 3 patients with thoracic hypokyphosis. Multivariate regression for thoracic parameters and TIS > 5.6 showed a significant correlation of pulmonary dysfunction in group 2 and 3 curves with apex between T1-T4, whereas transverse thoracic diameter, rib-apex distance, and hemithorax height were weakly associated. Conclusion: Thoracic inlet index (TI) is a neglected pre-operative variable associated with pulmonary dysfunction in thoracic kyphoscoliosis that can be evaluated on MRI without an additional cost and radiation.

637

P067: The Effect of Lumbosacral Fusion on Scoliotic Curves in Patients with Co-Existing Spondylolysis/Spondylolisthesis—A Retrospective Study of Clinical, Functional and Radiological Outcomes

Dilip Chand Raja Soundararajan ¹ , Shanmuganathan Rajasekaran ¹ , Ajoy P Shetty ¹ , and Rishi Kanna ¹

¹ Ganga Medical Centre and Hospitals Pvt Ltd, Spine Surgery, Coimbatore, India

Introduction: The association of scoliosis with spondylolisthesis is well known. However, there is no sufficient literature on the various patterns of scoliotic curves, clinical presentation, surgical consensus and outcomes of these curves except few case reports. Aim: To analyse the clinical, functional and radiological outcomes of lumbosacral fusion in patients affected by scoliosis with lysis or/and listhesis and prognosticate the scoliotic behaviour based on them. Materials and Methods: A retrospective analysis was performed from the year 2008-2018. All patients managed with co-existing scoliosis and listhesis/lysis were included. Degenerative and Secondary scoliosis along with patients without two year follow up were excluded. Clinical profile, Radiographic measurements and Functional outcomes were analysed and compared between preoperative and post-operative indices calculated at 2 years following procedure. The outcomes were analysed amongst 3 groups (Olisthetic-Group-1, Sciatic-Group-2, and Idiopathic-Group-3). Results: 18 patients were enrolled in the study (18 females, 2 Males). The study groups included Olisthetic (7 Females), sciatic (4 Females) and Idiopathic (7 patients- 5 Females: 2 Males). Mean age was 13.85 ± 2.41 (group-1), 15.5 ± 2.64 (group-2) and 22.57 ± 9.32 (group-3) years with no significant difference. Preoperative Lumbar curve severity, Coronal decompensation and Lumbar lordosis were significantly different between the groups. The mean preoperative lumbar curve of 51.14 ± 15.49 (Group-1) reduced to 41.157 ± 18.96 following lumbosacral fusion. All except one in this group had curve regression. The mean preoperative lumbar curve of 31 ± 7.78 (Group-2) reduced to 16 ± 3.91 and increased from 36.33 ± 10.65 (Group-3) to 44.66 ± 9.97 following lumbosacral fusion. Though, all except one had Level 1 satisfaction in NASS index, sciatic group had better functional outcomes in SRS-22 scoring system. The mean preoperative ODI scores were 50.8 ± 6.8% (olisthetic group), 27.5 ± 9.57% (sciatic group) and 46.57 ± 11.42% (idiopathic group) and significant difference was noted between sciatic and other groups (p value =.016). The mean postoperative scores were 6.57 ± 2.22% (olisthetic group), 1.5 ± 1.91% (sciatic) and 6 ± 3.26% (idiopathic) with significant difference between sciatic and other groups (p value = .027). Within groups there was a significant improvement in ODI scores in torsional and sciatic groups but not in idiopathic group (p value= .109). Conclusion: This is largest available data on outcomes of patients with scoliosis co-existing with spondylolisthesis in recent literature. Three specific patterns of scoliosis need to be identified to prognosticate progression/regression of scoliosis following lumbosacral fusion. Radiological characteristics of each pattern have been described in detail to correctly designate the patient in to one group. Not all patterns behave in the same way following lumbosacral fusion. Sciatic curves respond well compared to moderate reduction in olisthetic curves whereas idiopathic curves show progression.

657

P068: Multi-Disciplinary Approach to Large Myelomeningocele

Mohamed Badri ¹ , Kais Maamri ² , Mourad Masmoudi ¹ , Ghassen Gader ¹ , Mouna Rkhami ¹ , Sarah Houimli ³ , Jalel Kallel ⁴ , and Ihsen Zammel ¹

¹ El Manar-Tunis university, Faculty of Medicine of Tunis, Burns and Trauma Center, Ben Arous, Tunisia., Department of neurosurgery, Ben Arous, Tunisia

² Fattouma Bourguiba University Hospital, Department of Neurosurgery, Monastir, Tunisia

³ El Manar-Tunis university, Faculty of Medicine of Tunis, Burns and Trauma Center, Ben Arous, Tunisia, Department of Plastic surgery, Ben Arous, Tunisia

⁴ National Institute of Neurology, El manar-Tunis University, Faculty of medicine of Tunis, Neurosurgery department, Tunis, Tunisia

Introduction: Myelomeningocele is a neural tube defect in which spinal bones do not completely form. It consists in a herniation of both spinal cord, rootlets and meninges through a gap in the vertebral column. In some cases, a multidisciplinary approach combining neurological and plastic surgery is necessary to achieve a proper treatment of the disease. Material and Methods: Authors present a retrospective and multicentric study about challenging cases of myelomeningocele treatment in neurosurgical departments of both National Institute of Neurology and Trauma and Burns Center, in collaboration with plastic and reconstructive surgery department of Ben Arous. Dufourmental flap have been performed mostly and only one skin expansion have been tried. Results: The Dufourmental flaps technique has shown good results with an entire recovery in few months. The only case repaired with skin expansion evolved towards edge disunion. Conclusion: Multi-disciplinary repair to meningoceles with large defect treatment is often required. Locoregional flap following a Dufourmental technique is an efficient method to obtain an excellent recovery.

695

P069: Relevance of Deformity Correction for AIS Patients

Pedro Fernandes ¹ , Joaquim Brito ¹ , and Isabel Flores ²

¹ Centro Hospitalar Lisboa Norte, Orthopaedics, Lisboa, Portugal

² Iscte- Instituto Universitário de Lisboa, Estatística, Lisboa, Portugal

Introduction: It is well recognized the difficulty in correlating residual curve magnitude or percent of curve correction with overall quality of life using the SRS22 score. The authors investigate to what degree this lack of relevant correlation could vary in the presence of a complication. Material and Methods: Eighty-two adolescents (F = 69), with a mean age of 14.9 and Cobb angle of 63.45°, were consecutively operated on with posterior spinal fusion. All SRS-22 questionnaires and radiographs were present for review; 95.1% of the patients had a minimum follow-up of 24 months. Correlations were tested using Spearman Rank and linear and logistic regression analysis with standardized variables. Results: The mean post-operative final Cobb measurement was 22.05° (min 1°; max 41°), and the mean final percent of correction (Corr2) was 63.96 (min. 1, max. 94., SD = 17.86); 11.61 levels were fused on average (min 5; max 15, SD = 2.27). Eleven patients had complications; 10 patients returned the operating room for unplanned procedures (RORUP); seven patients had instrumentation removed for late infection. No correlation was found between the final Cobb angle and SRS-22 score [r = .021(P = .853)] but a small correlation [beta(Corr2) = .256; P = .023] was present between Corr2 and SRS-22 scores [R2 = .066;F(1.77) = 4.956;(P = .023)]. Crossing RORUP with Corr2 linearly, increased the explanatory power [R2 = .104; F(2,76) = 3.919; (P = .016)] but Corr2 lost its relevance [beta(Corr2) = .161; P = .187] with a trend towards negative correlation between RORUP and SRS-22 score (beta(RORUP) = −.217; P = .076). Adding a moderated variable (product of final correction and RORUP = 1) it increased the model’s explanatory power [R2 = .165; F(3.75) = 4.160 (P = .003)] with a beta for the moderator (RORUP) of .402 (P = .021). Conclusion: A variable which is able to neutralize the individual effect of another variable, points to the primacy of crossing the two together. In this case the percentage of final correction was mostly relevant to patients returning to the operating room, while not affecting the quality of life for those that did not. The study showed that a complication may either truly alter outcome, or the way adolescents evaluates curve correction or their clinical experience.

773

P070: Efficacy of Revising Traditional Growth Rods to Magnetic Expansion Control Growing Rods

Amir Reza Amiri ¹ , Edel Broomfield ¹ , Mark Harris ¹ , Stewart Tucker ¹ , and Deborah Eastwood ¹

¹ Great Ormond Street Hospital, Orthopaedic and Spinal Surgery, London, United Kingdom

Introduction: Control of scoliosis in children with early onset scoliosis who do not respond to conservative measures is challenging. Over the past decade the use of Magnetic Expansion Control growing (MAGEC) rods has increasingly become the operative method of choice for controlling early onset scoliosis. Despite the high costs associated with MAGEC, it potentially prevents the multiple lengthening operations required with the use of traditional growth rods (TGR). Subsequently, some children undergo revision of their TGR to MAGEC. It has been shown that the mean lengthening achieved with each growth rod distraction decreases with successive attempts. This is known as the “law of diminished returns”. Furthermore, the use of TGR has been associated with premature auto-fusion of the spine in 89% of children. There is limited information available surrounding effectiveness of revising TGR to MAGEC. We hypothesis that patients who undergo revision of TGR to MAGEC have limited remaining capacity for further spinal growth. To investigate this further we retrospectively reviewed all patients who underwent revision of TGR to MAGEC in our institute. Material and Methods: A retrospective observation review of all patients who had revision of TGR to MAGEC between 1st March 2010 and 1st March 2020. Spinal column lengthening was measured on anteroposterior whole spine radiographs. Measurements were taken between the superior endplate of the proximal and inferior endplate of distal vertebrae in which fixations were inserted. Known diameters of the implanted rods were used to calibrate and standardise the measurements. Results: 8 patients underwent revision of their TGR to MAGEC, 4 of which were female. 2 patients had congenital scoliosis, 2 had neuromuscular scoliosis and 4 had idiopathic scoliosis. Median age at insertion of TGR was 4.5 (4.3-5.6) years. TGR were revised to MAGEC after 4.6 (3.8-6.1) years. Median age at insertion of MAGEC was 9.2 (8.9-10.0) years. Children were followed up for 4.7 (4.4-5.2) years after insertion of their MAGEC rods. At the time of this review, two patients had undergone definitive fusion surgery. Overall a median of 28.9 mm (22.3-44.7) distraction was achieved with TGR, and 4.6 mm (1.1-12.0) with MAGEC. When taking in to account the number of years each method of distraction was used, an 8.23 (6.0-9.0) mm/year of spinal distraction was achieved during the use of TGR and 1.0 (.2-2.6) mm/year with MAGEC (P < .001). Conclusion: Based on our experience there is limited potential remaining for spinal lengthening when revising TGR to MAGEC. Our finding is likely to be due to progressive scarring, stiffness and development of autofusion during patient’s treatment with TGR. The principle of diminished return seems to have been well-established during their treatment with TGR, resulting in failure of growth with MAGEC. Given the high financial costs and the risks associated with the use of MAGEC, our results should be strongly considered by clinicians when considering revising TGR to MAGEC.

780

P071: Surgical Treatment of Diastematomyelia: Report of 8 Cases

Mohamed Badri ¹ , Mourad Masmoudi ¹ , Kais Maamri ² , Ghassen Gader ¹ , Mouna Rkhami ¹ , Kamel Bahri ¹ , and Ihsen Zammel ¹

¹ El Manar-Tunis university, Faculty of Medicine of Tunis, Department of Neurosurgery, Burns and Trauma Center, Ben Arous, Tunisia., Ben Arous, Tunisia

² Fattouma Bourguiba University Hospital, Department of Neurosurgery, Monastir, Tunisia, Monastir, Tunisia

Introduction: Diastematomyelia is a rare congenital condition that consist in the split of the spinal cord in a sagittal plane resulting in the constitution of two hemi-cords. This condition occurs in the presence of an osseous, cartilaginous or fibrous septum in the central portion of the spinal canal. Generally associated with different malformations such as spinabifida, syringomyelia and other neurological, osseous and general malformations. Material and Methods: Authors present a series of 8 patients presenting with scoliosis and lumbar hypertrichosis with normal neurological findings. All our patients underwent a spinal X-Ray, spinal CT-scan and spinal MRI, that showed type II diastematomyelia having an osseous septum deviding the spinal cord with duplication of the dura-mater, associated to a tethered spinal cord syndrome. Results: All our patients have received surgical treatment aiming to prevent neurological complications. Resection of the osseous septum and reunion of the two hemi-cords in the same thecal sac was the first surgical intervention followed by the dethereing of the spinal cord. Conclusion: Clinical and imaging findings should lead to an early diagnosis of no neurological signs diastematomyelia. An early surgical approach should lead to the prevention of neurological complications.

842

P072: The Finite Element Method Reveals Asymmetrical Stress Distribution in the Facet Joint of AIS

Yasuhito Yahara ¹ , Shoji Seki ¹ , Hiroto Makino ¹ , Katsuhiko Kamei ¹ , and Kawaguchi Yoshiharu ¹

¹ University of Toyama, Department of Orthopaedic Surgery, Toyama, Japan

Introduction: The vertebral body and intervertebral disc symmetrically transmit 70% of the load, and the facet joint compensates for the remaining 30% of the distribution in normal individuals. On the other hand, in patients with adolescent idiopathic scoliosis (AIS), the facet joints increase unbalanced loads because of abnormal torsion and rotation of the spinal column. Abnormal spinal column alignment due to AIS can increase asymmetrical mechanical loading in the facet joint, resulting in the degeneration of articular cartilage, subchondral bone sclerosis, and hypertrophy. However, there are no biomechanical evidence and analysis which focus on the stress distribution on the facet joints in patient with AIS. We hypothesize that the unbalanced stress distribution and mechanical loading on the facet joints could affect the rigidity of the scoliotic curvature of AIS. The purpose of this study is to investigate the stress distribution in the facet joints of AIS using the finite element method. Material and Methods: A total of 22 AIS patients (Lenke type 1; n = 11, Lenke type 2; n = 12) who underwent scoliosis-correcting fixation at our institution were included. The mean age at surgery was 13.0 ± 1.5 years, and the mean thoracic Cobb angle was 52.8 ± 10.3 degrees. The contact reaction forces at the T3 to T12 facet joints were examined by the 3D-CT image-based finite element method. Further, the difference in thickness between the bilateral inferior articular processes from T1 to T11 was calculated using preoperative CT images. The delta facet thickness (dFT), defined as the difference in thickness between concave and convex was calculated. In addition, the CT values of the subchondral bone in the inferior articular process were evaluated. The bilateral facet joints of the patients were histologically evaluated. Results: The finite element method showed that the contact reaction force reached a maximum at the T9/10 facet joint in the concave side, which was 3.03 ± .93 times higher than the average of the facet joints. In addition, 98 ± 1.9% of the load was transferred through the concave facet joint at the T9/10 level. The dFT values reached a maximum in the T9 inferior articular process in the concave side, and the concave facet joints had significantly higher CT values than the convex ones (P < .01), indicating the subchondral bone sclerosis of the facet joints. Histologically, the facet joints in the concave side showed degenerative changes such as fibrillation of the articular cartilage and the cluster formation of articular chondrocytes. Conclusion: Our current data clearly showed that abnormal spinal column alignment due to AIS increased asymmetric stress distribution on the facet joint and the morphological changes, including the hypertrophy, degenerative changes, and subchondral sclerosis of the facet joints. The data provide novel insights to understand the detailed mechanical stress distribution on the facet joints in patients with AIS.

1028

P073: Mid-Term Clinical Functional and Radiological Outcomes of Treatment of Dystrophic Kyphoscoliosis in Neurofibromatosis-1 With One-Stage Posterior Only All Pedicle Screw Technique Using Strategic Anchor Point Method

Aju Bosco ¹ and Nalli Ramanathan Uvaraj ¹

¹ Madras Medical College, Orthopedic Spine Surgery Unit, Chennai, India

Introduction: Corrective surgery for dystrophic kyphoscoliosis in neurofibromatosis type-1(NF-1) is challenging. Most studies in literature describe the outcomes of deformity correction of dystrophic kyphoscoliosis performed using implants available before the advent of pedicle screws. These procedures, had a high rate of pseudarthrosis and implant failure leading to curve progression due to inadequate fixation strength, tendency of the internal fixation to pullout, and failure to control spinal balance. Hence, there was a need for additional anterior release to achieve deformity correction and supplemental anterior augmentation to prevent pseudarthrosis. However, these procedures are fraught with longer treatment cycles, greater morbidity and complications. Literature on the surgical management of dystrophic kyphoscoliosis in NF-1 with the one-stage posterior segmental pedicle screw mediated deformity correction is scant. We have analysed the outcomes of a simple, yet effective surgical strategy for correction of dystrophic kyphoscoliosis in neurofibromatosis type-1 using one-stage posterior-only-pedicle screw technique using strategic anchor point method. Materials and Methods: Seventeen NF-1 patients with dystrophic kyphoscoliosis (mean age of 17.5 ± 6.3 years), underwent deformity correction and fusion by posterior-only-pedicle screw technique. Thin slice computed tomography(CT) scan and magnetic resonance imaging(MRI) were used to meticulously analyse the vertebral morphology and plan the anchor points preoperatively. Due to the presence of severe vertebral deformity and dysplastic/aplastic pedicles, pedicle screws were strategically anchored into key vertebrae including stable and neutral vertebrae in both the sagittal and coronal planes. Deformity correction was achieved by soft tissue releases and Ponte osteotomies followed by a combination of cantilevering and rod rotation techniques. Adequate autologous bone grafting was performed. Outcomes were analysed with respect to VAS(Visual Analogue Scale) scores for pain, SRS-22r(Scoliosis Research Society-22r) questionnaire, clinical and radiologic improvement in spinal balance, degree of correction achieved, and maintenance of correction at follow-up along with evidence of fusion on CT scan. Results: The average follow-up time was 28.2 ± 2.3 (range, 27-39) months. The mean operative time and mean blood loss were 306 ± 75.5 min and 950 ± 80.3 ml, respectively. Mean Cobb angle of scoliosis and kyphosis improved from 73.4 ± 11.5 degrees to 33.5 ± 8.3 degrees and 50.3 ± 21.6 degrees to 22.8 ± 10.5 degrees, respectively. Scoliosis and kyphosis correction rates were 55.6% (range, 12.4–69.6%) and 49.3% (6.4-75.7%), respectively. Mean loss of correction for scoliosis and kyphosis were 8.4 ± 2.3 and 6.7 ± 3.2 degrees respectively, at final follow-up. There was no case of neurological worsening. Statistically significant improvement was seen in the mean total SRS-22r scores [4.3 ± .5(3.8-4.5)] with significant improvement in the domains of pain, self-image, function, mental health, and satisfaction at final follow-up. There was one case of superficial wound infection which settled with debridement and antibiotics. There was one case of proximal screw pull-out which settled without affecting the clinical outcome. No case of revision surgery or pseudoarthrosis was observed. Conclusion: The technique is safe and effective in the treatment of dystrophic kyphoscoliosis in NF-1. Regaining total trunk balance is more important than Cobb angle correction of spinal deformities. An important treatment strategy is the inclusion of neutral and stable vertebra in both coronal and sagittal planes and use of abundant bone graft.

Keywords

neurofibromatosis, scoliosis, kyphosis, dystrophic, surgery, pedicle screws, bone graft

1124

P074: Management of Early Onset Scoliosis and Analysis of its Complications

Munjal Shah ^1,2 , Akshay Gadia ^1,2 , Arjun Dhawale ^2,3 , and Abhay Nene ^1,2

¹ Lilavati Hospital and research centre, Orthopaedic Spine, Mumbai, India

² Bai Jerabai Wadia Hospital for Children, Pediatric Orthopaedic Spine, Mumbai, India

³ Sir HN Reliance Foundation Hospital and Research Centre, Orthopaedic spine, Mumbai, India

Introduction: Early onset scoliosis (EOS) is a complex spinal deformity and delaying the fusion by casting or growing rods are feasible options. However, many reports have questioned the risk-benefit ratio of growing rod instrumentation owing to associated complications. This study is a retrospective analysis of complications associated with management of patients with EOS treated by casting (C) or growing rods (GR) at a single Indian center. Material and Methods: This study comprised of 15 patients of EOS undergoing either C or GR. Demographics, radiological parameters and treatment details were recorded. Complications along with planned and unplanned interventions were recorded. In casting group, removal or exchange of cast before planned schedule was considered as an unplanned event while in GR group return to operating theatre before the scheduled time for distraction was considered as an unplanned event. Results: Of the 15 patients who met the inclusion criteria, There were 6 patients in group C whereas 9 in group GR. 2 patients were managed initially by casting and were later converted to GR. The average age of patients treated with casting was 3.47 years (range 1-7 years) while that with GR was 3.22 years (range .91-5.55 years). Mean follow up of group C was 27.33 ± 30.46 months while that of group GR was 61.67 ± 42.56 months. Average number of procedures per patient in group C was 3.33 ± 1.88 while that in group GR was 6.78 ± 4.30. The mean number of complications per patient in group C was .67 ± .82 (range: 0-2) while that in group GR was 3.33 ± 2.18 (range: 1-8). The mean ratio of planned to unplanned intervention in group C was 2.83:0.50 while that in group GR was 6.22:0.56. Conclusion: Complication rates are higher in patients undergoing GR in early age as compared to those undergoing casting. GR is also associated with significantly higher rates of unplanned interventions as compared to casting.

1132

P075: Does Variation in Radiological Parameters Determine Cosmetic Appearance in Idiopathic Scoliosis? A Clinico-Radiological Analysis

Viswanadha Arun-Kumar ¹ and J Naresh-Babu ¹

¹ Mallika Spine Centre, Department od Spine Surgery, Guntur, India

Introduction: The cosmetic deformity in adolescent scoliosis is often not completely understood, assessed and documented. It is very common to see two patients with AIS who has same radiological measurements especially cobb angle and have quite different cosmetic appearance altogether or vice versa. One of the reasons for such observations may be due to discrepancies between cosmetic and radiological evaluation in AIS. The literature describes many radiographic parameters that have been developed to evaluate shoulder balance and truncal balance. However, till date the consideration given to cosmetic deformity along with radiological parameters remains inadequate. The purpose of the present study is to investigate how accurately radiological measurements correlate with cosmetic indices in patients of AIS. Material and Methods: A retrospective review of AIS patients from 2009 to 2019 was performed and a total of 38 AIS cases were identified. Patients with non-idiopathic scoliosis, fixed pelvic deformities or limb length discrepancy were excluded from the study. Pre and Post-operative radiographic films included whole spine standing in AP & lateral, side bending views to evaluate flexibility and traction in AP view assess the amount of correctable deformity. Radiographic parameters were measured on whole spine standing radiographs and Cosmetic indices were measured based on TRACE clinical tool. Both the findings were correlated by correlation analysis. Results: Radiographic Parameters—The radiographic changes after surgery suggest decrease in the magnitude of the deformity. There is significant decrease in the PT, MT and TL/L Cobb angle after deformity correction (P-value < .05). Highest correction took place in MT curves (54 ± 24%) followed by TL/L (52 ± 18%) and PT Curves (28 ± 17%). A statistically significant leftward trunk shift was evident in post-operative radiographs (P-.0046). Coronal and Sagittal correction has been statistically insignificant since most of the patients do not have any spinal imbalance. Cosmetic Indices—As per TRACE index, shoulder asymmetry was decreased from 1.73 ± .98 to .86 ± .68, hemi-thorax asymmetry has changed from 1.26 ± .73 to .2 ± .40, scapular asymmetry has decreased from 1.63 ± .76 to .96 ± .71 and finally waist asymmetry has changed from 2.76 ± .97 to .93 ± .82. Change in TRACE index has been extremely significant (P-value < .0001). Correlation analysis to show how well radiographic changes associate with cosmetic changes after deformity correction surgery yielded good to fair (r ≤ .7) significant correlation. PT Curve Correction has good correlation with Shoulder Height Index with r = .64. TL/L Curve Correction has good correlation (r = .56) with Scapular Height Index. Conclusion: In the present study, good correlation between various radiographic and cosmetic indices were observed. However, none of the correlation coefficients were greater than .7 which suggests that radiological evaluation could only partially reflect the cosmetic appearance in AIS patients. Surgeons should be aware of the fact that excessive reliance on magnitude of deformity correction in the assessment of patient’s cosmesis is inadvisable.

1147

P076: Sympathetic Outflow Disturbances Following Posterior Deformity Correction: A Rare Complication

Nirdesh Hiremaglur Jagadeesh ¹ , Vikas Tandon ¹ , and Abhinandan Reddy Mallepally ¹

¹ Indian Spinal Injuries Center, Spine Services, New Delhi, India

Introduction: Sympathetic system injury is a known but rare complication in scoliosis deformity correction. It is not common following posterior correction. We report a case of diastematomyelia with neuromuscular scoliosis with unusual complication of sympathetic outflow disturbance, after posterior instrumented correction. Material and Methods: A 13-year-old girl presented with complaints of deformity in the back first noticed 4 years ago. Roentgenogram revealed a right thoracolumbar kyphoscoliotic deformity of 105 with apex at T8 with nonstructural lumbar and cervicothoracic curves with positive sagittal alignment. Magnetic resonance imaging showed split-cord malformation with bony crest near the apex of the curve. Detethering followed by removal of the bony crest and restoration of the dual dural sleeves of the split cord into single neural tube was done in the first stage. In the second stage, pedicle screw fixation with was done from D3 to L3. Deformity correction was achieved using multilevel Smith Peterson osteotomy and concave rib osteotomy. On the second postoperative day, intensive care unit staff noticed persistent sinus tachycardia and profuse sweating in both upper limbs, chest, and upper-back. Twenty-four-hour Holter monitoring did not reveal any abnormality. Patient improved gradually and was discharged on postoperative day 9 when both sinus tachycardia and hyperhidrosis resolved. Results: Child was mobilized from the post operative day 5 and the symptoms of sympathetic overactivity reduced on post operative day 9. Child was comfortable at the time of discharge. Conclusion: Sympathetic chain disturbances after surgery recover with time. The exact time duration needed for recovery is not yet defined, however. Spine surgeons should be aware of this postsurgical complication and identify it so that management can be initiated. The symptoms may be long and drawn out, thus the roles of communication with and counseling of the patient as cannot be underemphasized.

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P077: Clinical Functional and Radiological Outcomes of Treatment of High-Grade Dysplastic Lumbosacral Spondylolisthesis by In-Situ Fusion Using Posterior Lumbosacral Transfixation Using Transdiscal Screw Construct

Aju Bosco ¹ and Nalli Ramanathan Uvaraj ¹

¹ Madras Medical College, Orthopedic Spine Surgery Unit, Chennai, India

Introduction: The surgical management of high-grade (Meyerding grade III or more) dysplastic lumbosacral spondylolisthesis (HGDSL) is challenging and aims to halt slip progression, achieve neural decompression and restore global sagittal spinal alignment with a solid fusion that can withstand high shear forces across the lumbosacral junction. Literature on the surgical treatment of HGDSL is conflicting and controversial. The various surgical techniques described in literature have their own benefits and disadvantages. However, the existing literature is limited by a low level of evidence with regards to the superiority of one technique in comparison with another. We have analysed the outcomes of instrumented in-situ fusion with posterior lumbosacral transfixation using transdiscal screws in the treatment of HGDSL. Materials and Methods: We did a retrospective review of a prospective cohort of 10 patients (1 male and 9 females) with L5-S1 HGDSL treated by insitu fusion using L5-S1 transdiscal screw constructs. A detailed preoperative clinical and radiological assessment of the deformity and the regional and global spinal balance was done before planning the treatment. Clinical and functional outcomes were analysed during follow-up using Visual Analogue Scale (VAS) scores and Oswestry Disability Index (ODI) scores. Radiologic outcomes were analysed with respect to spinopelvic parameters, radiographic evidence of fusion on computed tomography (CT) scan, and progression of deformity at follow-up visits. Results: The mean age at presentation was 36.7 ± 9.4(range, 21-55) years. All patients presented with instability type back pain with normal neurology with 60% presenting with concomitant radiculopathy. The mean follow-up was 38.9 ± 20.7 months (range, 28-96 months). The mean preoperative VAS score (8.4 ± 1.2) improved to 2.2 ± 1.0 postoperatively, P < .05. The ODI score showed a significant improvement from a mean preoperative value of 57.9 ± 9.6 to 14.9 ± 3.8 postoperatively, P < .05 There was radiographic evidence of stable fusion on CT scan at a mean of 9.3 ± 4.1 months (range, 7 to 12 months), with no evidence of progression in slip percentage or slip angle at the final follow-up. The slip angle showed a slight improvement from a mean preoperative value of 15.2 degrees (range, 12-36 degrees) to a mean postoperative value of 12.8 degrees (8 to 18 degrees). There were no neurologic deficits, implant failure or pseudoarthrosis at final follow-up. There was one case of superficial wound infection which settled with antibiotics. Conclusion: Surgical reduction of HGDSL is associated with a high risk of neurological complications. Surgical reduction of HGDSL is indicated only in cases with an unbalanced pelvis. In a case of HGDSL with a balanced pelvis in situ fusion with posterior lumbosacral transfixation using transdiscal screws is a safe and effective technique, in the treatment of L5-S1 HGDSL as evidenced by the good clinical, functional and radiologic outcomes at mean follow-up of 38.9 ± 20.7 months.

Keywords

Lumbosacral, spondylolisthesis, high grade, dysplastic, surgery, in-situ fusion, transdiscal screws

1302

P078: Early Medical Complications After Posterior Spinal Fusion in Adolescent Idiopathic Scoliosis

Jane McManus ¹ , Clare Byrne ¹ , Robin McManus ¹ , Henry Turner ² , Patrick Kiely ¹ , and Seamus Linnane ¹

¹ Blackrock Clinic, Dublin, Ireland

² Children's Health Ireland at Crumlin, Dublin, Ireland

Introduction: A comprehensive understanding of the post-operative complications rates in adolescent patients undergoing posterior instrumentation and fusion is important in order to guide immediate post-operative management, provide pre-operative patient and parent counselling and to provide evidence for quality assurance measures. Many medical complications have been reported following scoliosis repair including pulmonary, gastrointestinal, infectious, and neurologic. There is wide variability in post-operative complication rates reported in the literature. Few studies have investigated the immediate postoperative medical complications in Adolescent Idiopathic Scoliosis repair. Material and Methods: We conducted a single centre retrospective study of patients undergoing posterior instrumentation and fusion from January 2014 to January 2019. Records were screened for demographics, operation times, length of stay, time to mobilize, time to first bowel motion, number and types of analgesia as well as respiratory, gastrointestinal (GI) and neurological complications. We analyzed pre and post op haematologic and biochemical parameters. Results: The overall complication rate was 10%. The respiratory system was most commonly affected in terms of post operative medical complications including lower respiratory tract infections and pleural effusions. We found a correlation between the incidence of respiratory complications and the types of analgesia used. GI complications including ileus, superior mesenteric artery syndrome and constipation. Haematologic complications including anaemia were commonly encountered. We saw a transfusion rate of 4%. Conclusion: Post operative medical complications occur in AIS in less than 10%. This is consistent with other previous studies. We believe that post operative analgesia regimes correlate to respiratory complications.

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P079: A Comparison of Hybrid and All Poly-Axial Pedicle Screw Construct in Correction of Idiopathic Scoliosis

Pranav Shah ^{1 2} , Rajesh Mangattil ¹ , and Arun Ranganathan ¹

¹ Royal London Hospital, Barts Health NHS Trust, Spine Surgery, Trauma & Orthopaedics, London, United Kingdom

² University Hospital of Wales, Spine Surgery, Trauma & Orthopaedics, Cardiff, United Kingdom

Study design: Single centre retrospective radiological analysis of idiopathic scoliosis correction comparing hybrid screw construct (poly-axial & mono-axial) to all poly-axial screw construct. Objective: Compare loss of correction between hybrid screw construct group (HSG) and all poly-axial screw construct group (PSG). Method: Retrospective review of preoperative, post-operative and latest follow-up radiographs for cohort of 42 patients over period of 28 months operated by single surgeon. Results: 19 patients (16 females, 3 male) in HSG and 23 (18 females, 5 male) in PSG. 3 patients excluded due to complications. Average age at surgery: 14 years for HSG and 15.8 years for PSG. The average baseline Cobbs angle for HSG was 64.57 degrees and 60.79 degrees for PSG. In the HSG, on average 11.6 levels were fused and, in the PSG, it was 11.3. Mean screw density for HSG was 1.54 and PSG was 1.6. Mean correction from pre-op to immediate post-op was 46.06 degrees (70.10%) in the HSG and 41.24 degrees (67.78%) in the PSG. At the last follow-up, mean correction was 45.12 degrees (68.0%) for the HSG and 42.43 degrees (70.39%) for PSG. Loss of correction from post-operative radiographs to latest follow up averaged 10.05% in HSG and 3.86% for PSG. Conclusion: Average loss of correction showed small difference in the two groups, not clinically significant. Both techniques offer same degree of correction and there is no advantage in using hybrid construct opposed to all-poly construct. Surgical time and ease of threading rods are in favour of an all poly-construct.

1638

P080: The Influence of Stature and Body Mass Index on Postoperative Curve Decompensation in Adolescent Idiopathic Scoliosis Patients Following Surgery Using Hook-Hybrid Versus All-Pedicle Screws Constructs

Samuel Wei Han Tan ^1,2 , Reuben Soh ¹ , Graham Goh ¹ , Chang Ming Guo ¹ , Seang Beng Tan ^1,3 , and John L.T. Chen ¹

¹ Singapore General Hospital, Orthopaedic Surgery - Spine, Singapore, Singapore

² Yong Loo Lin School of Medicine, Singapore, Singapore

³ Mount Elizabeth Novena Hospital, Orthopaedic Surgery, Singapore, Singapore

Introduction: There is a paucity of literature on the influence of physical stature and BMI on curve maintenance in Adolescent Idiopathic Scoliosis (AIS). Furthermore, studies comparing the relative effectiveness of pedicle screws (PS) and hook-hybrid (H) constructs in patients with a smaller stature, lower BMI and consequently smaller pedicle diameters are lacking. We aimed to (1) compare outcomes of H and PS constructs in AIS patients; and (2) investigate whether BMI or height may modify the effect of the type of surgical construct on the extent of curve decompensation. Material and Methods: This study retrospectively reviewed AIS patients who underwent surgical fixation with H or PS constructs at a single tertiary institution. Patients with implant density of at least 70% and 2-year follow-up were included. Demographic and perioperative data collected were age, sex, height, BMI, implant density and pedicle diameter. Cobb angles and curve correction were compared preoperatively, postoperatively and at follow-up. Results: In total, 59 patients were included. H group had a lower pedicle size at the highest level of construct and at T4 compared to PS group. Postoperatively, H group (30.19° ± 11.74°) and PS group (32.13° ± 10.35°) had similar correction (mean diff. 1.95°, P = .516). At 2-year follow-up, H group (1.59° ± 3.51°) and PS group (.0746° ± 2.82°) had similar curve deterioration (mean diff. 1.51°, P = .079). Uni- and multivariate analyses revealed that BMI and height were not associated with curve deterioration at 2-year follow-up among the H and PS groups. Conclusion: H constructs provided similar maintenance of curve correction at 2-year follow-up compared to PS constructs in a population with low BMI. Moreover, BMI and Stature did not modify curve deterioration between both groups at follow-up. This study supports the use of H constructs when faced with difficult pedicle morphology associated with shorter stature as it provides satisfactory long-term maintenance of curve correction.

1708

P081: Outcome of Posterior Only Approach Surgery for Treatment of Sever Rigid Scoliosis

Babak Mirzashahi ¹ and Mersad Moosavi ¹

¹ Joint Reconstrucion Research Center, Rothoprdic Department, IKH, Tums, Tehran, Iran

Introduction: The management of severe scoliosis may lead to significant complication and adequate mobilization is a key step to achieve maximal correction usually requiring extensive approaches. There is still no consensus in the management of these severe and rigid curves. In this study, we evaluated the clinical and radiologic outcome of posterior only approach with multilevel asymmetric Ponte osteotomy with minimum 2 years follow up. Material and Methods: In this retrospective study, 23 patients with severe and rigid adolescent idiopathic scoliosis who underwent surgery with a single-staged posterior only approach were included. The surgical procedure in these patients were excision of posterior ligaments and spinous process, partial laminectomy in caudal part of lamina, excision of the ligamentum flavum, facetectomies, and multilevel asymmetric posterior column osteotomies (Ponte) followed by instrumented fusion. Clinical records, including demographic data, operating time, hospitalization time, blood loss, number of segments instrumented, fused and osteotomized, functional improvement, follow-up duration and complications, were recorded. Results: The mean preoperative Cobbs angle of major curve in coronal plan was 97.5 (range, 82°-131°) with the mean flexibility of 21.4 (range, 10°-25°) on bending radiography. The mean immediate postoperative Cobbs angle of major curve was 34.8 (range, 17°-61°), showing a 64.2% correction. The mean preoperative coronal and sagittal imbalance of 3.8 cm and 4.2 cm were improved to 1.0 cm and 1.3 cm at postoperative measurements, respectively. A mean of 6.1 (Range: 5-9) vertebral segments were osteotomised. We experienced no major complications. Conclusions: We found that a posterior-only procedure in patients with severe and rigid adolescent idiopathic scoliosis could provide correction rate, coronal and sagittal balance, and clinical outcomes comparable with other procedures. Using this technique can eliminate the need for the anterior release, with the associated complications related to anterior surgery, in the treatment of severe rigid scoliosis.

1714

P082: Thoracic Kyphoscoliosis Secondary to Gorham's Disease

Mohamed Ghorbel ¹ , Mohamed Ben Jemaa ¹ , Achraf Lajmi ¹ , Mohamed Ayadi ¹ , Ameur Abid ¹ , Moez Trigui ¹ , Kamel Ayedi ¹ , Wassim Zribi ¹ , and Hassib Keskes ¹

¹ Habib Bourguiba University Hospital of Sfax, Tunisia, Orthopedic Surgery and Traumatology Department, Sfax, Tunisia

Introduction: Gorham's disease is a rare disease entity characterized by bone destruction secondary to uncontrolled vascular proliferation. It affects mainly children and young adults. It is characterized by a varied clinical presentation. We report through this work the case of a dorsal kyphoscoliosis secondary to Gorham's disease. Material and Methods: A 12-year-old girl was followed for a chylothorax which was drained then operated with surgical ligature of the thoracic duct. She consulted for back pain and deformity. On examination, she had a thoracic kyphoscoliosis with paresis of the lower limbs. MRI of the spine showed a kyphoscoliosis with signal’s abnormality of vertebral bodies from D5 to D10 associated with a pleural pocket next to the kyphosis. The patient underwent an anterior approach with left posterolateral thoracotomy, a resection of the pleural pocket with chylous content and an anterior release of the spine. Fifteen days later, she underwent an instrumented D2 L3 posterior arthrodesis. The dystrophic bone was the source of a sheet bleeding that was difficult to control. Results: The postoperative follow-up was simple with improved respiratory function, correction of kyphosis and disappearance of neurological signs. Pathologic study of bone and pleural biopsy confirmed the diagnosis of Gorham's disease. Conclusion: Gorham's disease is a rare pathology. The clinical presentation depends on the site of the disease. The presence of chylothorax is quite common. A better knowledge of the physiopathology of this disease will allow a better management surgery finds its place in the treatment of chylothorax and in the correction of bone deformities.

1717

P083: Horizontal Gaze Palsy and Progressive Scoliosis, About One Case and Literature Review

Mohamed Ben Jemaa ¹ , Mohamed Ghorbel ¹ , Achraf Lajmi ¹ , Tarak Bardaa ¹ , Ameur Abid ¹ , Moez Trigui ¹ , Kamel Ayedi ¹ , Wassim Zribi ¹ , and Hassib Keskes ¹

¹ Habib Bourguiba University Hospital of Sfax, Tunisia, Orthopedic Surgery and traumatology Department, Sfax, Tunisia

Introduction: Horizontal gaze palsy syndrome with progressive scoliosis (HGPPS), is a rare autosomal recessive neurologic disorder caused by mutations in the ROBO3 gene which has an important role in axonal orientation and neuronal migration during brain development. It is characterized by complete or almost complete absence of horizontal gaze and progressive scoliosis beginning in childhood. Material and Methods: A 16-year-old girl with no particular pathologic history who consults for a fortuitously discovered right hump. On examination, she had an unbalanced trunk with ocular signs such as horizontal gaze palsy and pendular nystagmus. The entire spine X-Ray revealed a right-convex dorso-lumbar scoliotic deformity with a Cobb angle of 30°. When examined again almost one year later, this patient had an unfavourable clinical and radiological course with a Cobb angle of 75°. The brain CT-scan showed suggestive lesions of HGPPS syndrome evoking the secondary origin of the scoliosis. She was treated surgically with posterior instrumented fusion of the spine. Results: The outcome was simple with satisfactory skin healing. A correction of the scoliotic deformity with a Cobb angle of 30° was clearly demonstrated by postoperative radiography. Conclusion: HGPPS syndrome is a rare inherited condition. Its management is multidisciplinary. Its prognosis depends on the early diagnosis and treatment.

Deformity-Thoracolumbar (Adult)

26

P084: Lumbar Central Canal Stenosis Affects the Outcome of Total Knee Arthroplasty

William Sheppard ¹ , Kevin McKay ¹ , Alexander Upfill-Brown ¹ , Howard Park ¹ , Gideon Blumstein ¹ , Akash Shah ¹ , Adam Sassoon ¹ , and Don Park ¹

¹ David Geffen School of Medicine at UCLA, Orthopaedic Surgery, Santa Monica, USA

Introduction: Recent database studies have noted reduced functional outcomes after total knee arthroplasty (TKA) in patients with pre-existing nonspecific lumbar stenosis. There is a paucity of information regarding the influence lumbar central canal stenosis (LCCS) has on outcomes after TKA. The purpose of this study was to address this deficit and expand upon potential relationships between the lumbar spine and TKA. We hypothesized that patients with severe LCCS have a decrease in both preoperative and postoperative arcs of motion when undergoing TKA. Material and Methods: This retrospective study investigated all TKAs for primary osteoarthritis at our institution between 2017 and 2020. A preoperative lumbar MRI and no prior lumbar spine surgery were necessary for inclusion. Stenosis severity was evaluated by (1) decreased AP diameter of the dural sac and (2) increased morphological grade from L1-S1. Preoperative/postoperative range and arc of motion, flexion contracture, and need for manipulation-under-anesthesia (MUA) were assessed in 104 TKAs (95 patients). Results: No significant findings related to decreased AP diameter and increased morphological grade were noted at any level for demographics, need for MUA, flexion contracture, postoperative arc-of-motion (AOM), and delta-AOM. Preoperative-AOM reduction was significant at levels L1-2, L2-3, L3-4, and L4-5 (P < .001 for each level) with decreasing AP diameter and increased morphological grade. A 16 degree and 5 degree reduction in preoperative AOM was noted at the most stenotic level (L3-4) with decreased AP diameter and increased morphologic grade, respectively (P < .001). Conclusion: Severe LCCS was demonstrated by a reduction in the AP diameter of the dural sac or increased morphological grade. This study showed a clinically significant reduction in preoperative-AOM in those with severe LCCS, which was not improved after TKA. Persistent postoperative reductions in AOM may contribute to reduced patient satisfaction, function, and overall recovery.

27

P085: Lumbar Sagittal Mismatch Deformity Negatively Affects Total Knee Arthroplasty Outcomes

William Sheppard ¹ , Alexander Upfill-Brown ¹ , Kevin McKay ¹ , Howard Park ¹ , Akash Shah ¹ , Don Park ¹ , and Adam Sassoon ¹

¹ David Geffen School of Medicine at UCLA, Department of Orthoapedic Surgery, Santa Monica, USA

Introduction: It has been well documented that spine pathology can have an adverse effect on total hip arthroplasty results. There is a paucity of data, however, to determine if a relationship exists between pre-existing spinal deformity and clinical outcomes following total knee arthroplasty (TKA). The purpose of this study is to determine if such a relationship exists. We hypothesize the lumbar sagittal mismatch deformity (MD) will result in decreased functional recovery, increased stiffness, and subsequent interventional requirement when compared to those without such deformity. Material and Methods: 933 consecutive TKAs (845 patients) performed between January 2017 and 2020 at our institution were retrospectively reviewed. TKAs were excluded if they were not performed for primary osteoarthritis (OA) or if pre-operative lumbar radiographs were unavailable/inadequate to measure sagittal parameters of interest: Pelvic Incidence (PI), Sacral Slope, Pelvic Tilt, Lumbar Lordosis (LL), and Deformity Mismatch. 94 TKAs were subsequently available for inclusion and divided into two groups: those with MD, as defined by |PI-LL|>10°, and those without MD. The following clinical outcomes were compared between the groups: total post-operative arc of motion (AOM), incidence of flexion contracture, and need for manipulation under anesthesia (MUA). Results: Of the 94 TKA’s included, 53 met the MD criteria, while 41 comprised the non-mismatch deformity (NMD) group. There were no significant differences in sex, age, body mass index (BMI), pre-operative knee range of motion (ROM), preoperative AOM, or opiate use between the groups. TKAs with MD were more likely to have MUA (P = .026), ROM <0-120 (P < .001), a decreased AOM by 16° (P < .001), and a flexion contracture post-operatively (P = .01). These findings remain consistent through multiple regression analyses. Conclusion: Pre-existing MD may adversely affect clinical results following TKA. Statistically and clinically significant decreases in post-operative ROM and AOM, increased likelihood of flexion contracture, and increased need for MUA were all noted in those with MD. These findings should prompt suspicion and potentially play a role in tempering physician and patient expectations following TKA in patients with MD.

33

P086: Technical Considerations of Uniportal Endoscopic Posterolateral Lumbar Interbody fusion. A Review of its Early Clinical Results in Application in Adult Degenerative Scoliosis

Pang Hung Wu ¹ , Hyeun Sung Kim ² , Ji Yeon Kim ² , and Il-Tae Jang ²

¹ National University Health Systems, Jurong Health Campus, Orthopaedic Surgery, SINGAPORE, Singapore

² Nanoori Gangnam Hospital, Seoul, Spine Surgery, Seoul, South Korea

Objective: Uniportal Endoscopic Posterolateral Lumbar Interbody Fusion provides one of the least invasive form of minmally invasive surgery allowing large size cages which were commercially available for open and tubular microscopic transforaminal lumbar interbody fusion (TLIF) to be inserted through this approach. We studied the effect of such a technique on a series of degenerative scoliosis patients who had low grade degenerative scoliosis. Methods: Uniportal Endoscopic Posterolateral Lumbar Interbody Fusion (Endo-TLIF) was applied to patients who had 10-40 degrees of degenerative adult scoliosis. Preoperative and post-operative one week, 3 months and final follow up clinical status of visual analog scale, Oswestery disability index, perioperative complications and MacNab’s criteria were collected. Roentgenogram to assess changes in Cobb’s angles were done. Results: There was statistically significant improvement of preoperative, 1 week post-operative, 3months post-operative and final follow up mean of Visual Analog Scale score with 7.72 (5-10), 3.68 (3-6), 2.88 (2-4) and 1.96 (1-3) respectively and with Oswestry Disability Index mean of 70.4 (52-86), 35.12 (26-56), 27.68 (24-38) and 24 (20-28) respectively, P < .05. In terms of MacNab’s criteria, 100% had good to excellent result. In terms of scoliosis measured by Cobb’s angle, there was statistically significant improvement. Conclusion: Uniportal Endoscopic Posterolateral Lumbar Interbody Fusion is a safe and effective procedure in mild to moderate degenerative scoliosis with good early clinical results and improvement in coronal Cobb’s angle, it can be considered as an option if a short segment(s) fusion is planned for adult degenerative scoliosis.

259

P087: Radiographic and Patient Reported Outcomes After Anterior Lumbar Interbody Fusion (ALIF) in Isthmic Lumbosacral Spondylolisthesis

Christopher Marvin Jesse ¹ , Othmar Schwarzenbach ² , Christian T. Ulrich ¹ , Andreas Raabe ¹ , and Ralph T. Schaer ¹

¹ Department of Neurosurgery, Inselspital, Bern University Hospital, Bern, Switzerland

² Das Rueckenzentrum, Thun, Switzerland

Introduction: The optimal surgical management of isthmic spondylolisthesis is controversial and reports on anterior approach for low-grade isthmic spondylolisthesis in the literature are scarce. We present the radiographic and patient reported outcomes after anterior lumbar interbody fusion in patients with symptomatic L5-S1 isthmic spondylolisthesis. Material and Methods: All adult patients with documented L5-S1 isthmic spondylolisthesis treated between 2008 and 2019 with ALIF were screened. All surgeries were performed by an experienced spine surgeon, through a retroperitoneal approach, a titan cage was inserted at L5-S1 with anchoring screws in the endplates. Prospectively collected clinical and surgical data as well as radiographic parameters were analyzed retrospectively. All patients were asked to complete the Oswestry Disability Index (ODI) and Core Outcome Measures Index (COMI) before and after surgery. Results: In total, 34 patients (19 men, 15 women) with a mean age of 52.5 (±11.5) years were included for final analysis. The mean maximal follow-up (FU) was 2.7 (±2.4) years, the mean ASA risk classification was 2.0 (±0.6). The mean pelvic incidence 64.9 (±8.7)°, 73.5% (n = 25) of patients had a spondylolisthesis grade I, 23.5% (n = 8) grade II and 2.9% (n = 1) grade III according to Meyerding classification. Mean lumbar lordosis increased from 58.9 (±9.4)° before surgery to 64.5 (±9.2)° after surgery. Mean COMI and ODI scores improved from 6.9 (±1.5) and 35.5 (±13.0) to 2.0 (±2.5) and 10.2 (±13.0), respectively after one year, and to 1.7 (±2.5) and 8.2 (±9.6), respectively after 2 years. The COMI score improved in 86.4% of patients after one year and 92.9% of patients after 2 years by at least the minimal clinically important change (MCIC) score of 2.2 points. Preoperatively, mean VAS values for back and leg pain measured 5.3 (±2.5) and 6.8 (±2.3), respectively, and improved to 1.9 (±1.8) and 1.7 (±2.5), respectively at one year FU (22/34 patients), and to 1.6 (±2.3) and 1.2 (±1.5), respectively at 2 years FU (14/34 patients). There were no records of intraoperative vascular or other major complications. The reoperation rate was 8.8% (n = 3) in the observation period. Conclusion: Patient reported outcomes after ALIF for symptomatic isthmic spondylolisthesis showed clinically important improvement after one and 2 years. These results suggest that with good patient selection and necessary surgical experience, the ALIF is an effective and save surgical treatment option for low-grade isthmic spondylolisthesis.

317

P088: Simultaneous sacroiliac joint fusion during pelvic fixation for adult deformity surgery—A case report series and technique description

Christopher Martin ¹ , Kenneth Holton ¹ , Kristen Jones ² , Jonathan N. Sembrano ¹ , David Polly ^1,2

¹ University of Minnesota, Department of Orthopaedic Surgery, Minneapolis, USA

² University of Minnesota, Department of Neurosurgery, Minneapolis, USA

Introduction: Pelvic fixation enhances long constructs for deformity. Subsequent loosening of iliac screws and pain at the pelvis occurs requiring revision at some rate. Concomitant sacroiliac (SI) fusion may prevent potential pain and failure. Posterior midline exposure of the spine and placement of thoracolumbar pedicle screws and S2AI screws is performed. S2AI screws are placed as caudal as possible, just above the sciatic notch, to allow space for the sacroiliac joint implant. Bilateral triangular titanium rods (TTR) are then placed across the SI joint with either fluoroscopy or computer-assisted navigation guidance. Material and Methods: Retrospective review of open SI joint fusions with TTR performed between 8/2019 and 3/2020. All patients underwent lumbosacral fusions through a midline approach and had bilateral S2AI pelvic fixation in the caudal teardrop, followed by TTR placed just proximal and cephalad to the S2AI screws using intra-op CT imaging guidance. Results: 21 cases were identified with 42 TTR placed, ranging in size from 7.0 × 65 to 7.0 × 90 mm. 3 TTR (7%) were found to be malpositioned intraoperatively, and each was successfully repositioned during the index surgery, with no negative sequelae. All breaches occurred in a medial and cephalad direction into the pelvis. Operative time averaged 8 minutes 33 seconds per TTR implant. Conclusion: Image guided open SI joint fusion with TTR during lumbosacral fusion is technically feasible. The bony corridor for implant placement is narrower cephalad, and implants tend to deviate medially into the pelvis. Detection of malpositioned implants is aided with an intra-op CT scan, but can be salvaged. A prospective, randomized clinical trial is underway which will better inform the impact of this technique on patient outcomes.

341

P089: Analysis of the Association Between the Number of Instrumented Leves, Complications and Quality of Life

Marta Esteban Blanco ¹ , Manuel fernandez ¹ , Julio Villar Perez ¹ , Domingo Lombao Iglesias ² , Jesus Betegon Nicolas ¹ , Andrés Blanco Hortas ² , Jose Hernandez Encinas ¹ , Ana Lozano Muñoz ¹ , and Leticia Gallego Diez ¹

¹ Hospital of Leon, León, Spain

² Hospital of Lugo, Lugo, Spain

Introduction: The number of instrumented levels in deformity surgery is associated with a high rate of complications. The objective has been to analyze the risk of complications and the quality of life according to the instrumented levels. Material and Methods: A cohort of patients in the period 2016-2017 who underwent adult deformity surgery was retrospectively analyzed. Patients with 4 or more instrumented vertebrae were included and 2-years follow-up was performed. The patients were divided into two groups according to the number of instrumented levels, the turning point was 8 instrumented levels. The quality of life questionnaires used were the VAS, ODI and the SRS22. Statistical analysis was performed using the Chi-test for categorical data, analyzing the association using the Odds Ratio, and t-test was used to compare pre-post means in the Quality of Life analysis. Results: 48 patients were included (83% women). 22 patients with less than 8 levels instrumented and 25 with more than 8 levels. The group with ≥ 8 levels is 77% more likely to have complications than in the group with <8 levels. [OR = 1.77 (CI95% .54-5.81] and 21% more than having an infection [OR = 1.21 (CI95% .23-6.09)], although this finding is not statistically significant. Regarding the improvement in quality of life, improvement in both groups were observed, although it was only statistically significant in Pain subdomain of the SRS-22 (P < .05). It was highlight from the results that patients with ≥ 8 levels improve more regarding their perception of the image, in patients with <8 levels the improvement in disability is substantially greater compared to the other group, although there are no statistical differences. Conclusion: Risk of complications was determined by having a greater number of instrumented levels, although the differences between groups were not statistically significant. In general terms, the quality of life improves in both groups, more in the group ≥ 8 levels, but without statistically significant differences.

361

P090: Sacroiliac joint arthropathy after long construct fusions using S2-alar-iliac instrumentation: a tale of two screws

Elliot Pressman ¹ , Mohammad Hassan A. Noureldine ² , Jay I. Kumar ¹ , Nam D. Tran ¹ , Mark S. Greenberg ¹ , and Puya Alikhani ¹

¹ University of South Florida, Neurosurgery & Brain Repair, Tampa, USA

² University of South Florida, Surgery, Tampa, USA

Introduction: Sacroiliac joint (SIJ) arthropathy is an increasingly recognized problem in patients undergoing long construct surgery and may account for a subgroup of patients diagnosed with failed back surgery syndrome. S2-alar-iliac (S2AI) screw instrumentation is thought to decrease its incidence. This study aims to compare SIJ outcomes in patients with long constructs to pelvis with partially threaded (PT) versus fully threaded (FT) S2AI screws. Material and Methods: Data of eligible patients were collected from a prospectively maintained database with retrospective review of electronic records at a tertiary academic medical center. We included consecutive patients who underwent instrumentation with bilateral S2AI screws, either PT or FT, between 2016 and 2019. Exclusion criteria included prior SIJ fusion. Results: Sixty-five consecutive patients underwent S2AI screw instrumentation (40 in PT group, 25 in FT group) and were enrolled. Length of hospital stay, discharge disposition, postoperative Oswestry Disability Index, occurrence of proximal junctional break/failure/kyphosis or distal junctional break/failure/kyphosis (DJBFK), time to DJBFK occurrence, and length of follow-up were not significantly different between the two groups. The rate of postoperative back pain was significantly less in the PT group compared to the FT group (Visual Analog Scale 1.3 versus 2.1). The rate of postoperative SIJ pain was higher in the PT (52.5%) compared to FT (32%) group. There was a significantly shorter time-to-pain development in the PT compared to FT group (11.8 versus 20.1 months, respectively). Of those who developed SIJ pain in the PT group, the pain worsened in 80.9% versus only 25% of those in the FT group despite conservative treatment. Cox regression found the PT group to be more likely to develop SIJ pain at any point during follow-up compared to the FT group (Hazard Ratio=7.308). SIJ fusion was not detected on imaging studies of any patient during follow-up. Conclusion: SIJ arthropathy is common following long construct fusion. Our results suggest that FT S2AI screws are associated with better SIJ outcomes compared to PT S2AI screws. However, S2AI screw instrumentation is not sufficient to achieve fusion or prevent the development of SIJ pain. Concurrent SIJ fusion may be necessary in patients with long constructs to prevent SIJ arthropathy. Future studies are crucial to validate this hypothesis.

571

P091: Do We Really Know Risk Factors and Etiology of Proximal Junctional Kyphosis (PJK)?

Marta Esteban Blanco ¹ , Manuel Fernandez ¹ , Julio Villar Perez ¹ , Domingo Lombao Iglesias ² , Jesus Betegon Nicolas ¹ , Andrés Blanco Hortas ² , Jose Hernandez Encinas ¹ , Ana Lozano Muñoz ¹ , and Leticia Gallego Diez ¹

¹ Hospital Of Leon, León, Spain

² Hospital Of Lugo, Lugo, Spain

Introduction: Currently there is no consensus among the authors on the etiology and risk factors of proximal junctional kyphosis (PJK). The objective of our study was to analyze our cases of PJK and the possible relationship with the published risk factors. Material and Method: A cohort of patients undergoing adult spine deformity surgery was retrospectively analyzed. 2-years follow-up were included. Statistical analysis was performed using the t-test for the comparison of means in variables that follow a normal distribution and non-parametric Mann-Whitney test for variables that do not follow it. Results: 69 patients were included (79.7% women). 10 patients were included in the PJK group. Both groups were comparable, it was highlight how the age is higher in patients who have suffered a PJK, this may be related to osteoporosis and muscle weakness. Analyzing pre radiological parameters in both groups we found that patients with PJK have greater thoracic kyphosis (44.00 ± 11.83), lumbar lordosis (50.50 ± 15.60) and more pelvic incidence (68.40 ± 9.84) in comparison with the other group thoracic kyphosis (38.86 ± 18.11), lumbar lordosis (39.28 ± 25.93) and pelvic incidence (49.50 ± 14.88), although the differences were not statistical significant (thoracic kyphosis (P = .135), lumbar lordosis (P = .227) and pelvic incidence (P = .500). Regarding patients with PJK, we did not find statistically significant differences (P = .642) in the PI-LL mismatch pre-surgery (17.90 ± 15.13) and post-surgery (15.00 ± 13.76). Alteration in the Roussouly profile were not found except in 3 cases after primary surgery. Statistically significant differences (P = .025) were found in thoracic kyphosis in patients with PJK before primary surgery (44.00 ± 11.83) and immediately before the PJK (58.80 ± 16.69). Conclusion: In our study, we saw a relationship in terms of the risk factors for PJK, greater thoracic kyphosis, lumbar lordosis and pelvic incidence. The most important was the relationship between thoracic kyphosis after the first surgery and the appearance of PJK.

585

P092: The AOSPINE Adult Spine Deformity Patient Profile Classification System—The Development, Validation and International Expert Consensus

J Naresh-Babu ¹ , Kenny Yat Hong Kwan ² , Yabin Wu ³ , Caglar Yilgor ⁴ , Ahmet Alanay ⁴ , Kenneth Man Chee Cheung ² , David Polly ⁵ , Jong-Beom park ⁶ , Manabu Ito ⁷ , Lawrence Lenke ⁸ , Miranda van Hoff ⁹ , and Marinus De Kleuver ⁹

¹ Mallika Spine Centre, Spine Surgery, Guntur, India

² Queen Mary Hospital, The University of Hong Kong, Hong Kong, Hong Kong

³ AO Spine, Switzerland, Swaziland

⁴ Comprehensive Spine Center at Acibadem Maslak Hospita, Acibadem University School of Medicine, Dep. of Orthopaedics and Traumatology, Turkey, Turkey

⁵ University of Minnesota, Minnesota, USA

⁶ Uijeongbu St. Mary's Hospital, Department of Orthopaedic Surgery, Gyeonggi-do, South Korea

⁷ Hokkaido Medical Center, Sapporo, Japan

⁸ Columbia Univ., Dept. of Orthopedic Surgery, Newyork, USA

⁹ Radboud university medical center, Department of Orthopaedic Surgery, Nijmegen, The Netherlands

Introduction: The evaluation of patients with Adult spine deformity (ASD) involves a comprehensive assessment. Each patient of ASD presents with unique combination of pain, disability and risk factors along with a radiological deformity making it difficult to develop a reliable classification. The available classifications of ASD are predominantly radiological in nature. A comprehensive patient profile that helps to capture full picture of ASD patients in an uniform and organised manner is lacking. The purpose of this study was to propose a multimodal systematic approach of gathering information on the factors that drive decision-making by developing a comprehensive ASD patient profile. Materials and Methods: The present study comprises of three parts. Part 1: Development of prototype of patient profile: The data from the Core Outcome Study on SCOlisis (COSSCO) by Scoliosis Research Society (SRS)was categorised into a conceptual framework develop a prototype. Part 2: Modified Delphi study: 51 panellists participated in a four round iterative process, panellists were asked to respond and comment to series of questions. Anonymous and controlled feedback of group response was presented to the panellists before each subsequent round. Items reaching >70% agreement were included. Part 3: Pre-test validation: Nine experts participated in a survey. Content validity and usability were evaluated quantitatively. The content validity index (CVI), the content validity ratio (CVR) and the average CVI (Ave-CVI), item CVI (I-CVI) for relevance were calculated. A Usability survey with a seven-point Likert scale for agreement was conducted. Results: The process of brainstorming on the domains, factors and measurement instruments yielded a prototype of ASD patient profile system which was subjected to Delphi consensus study.The developed profile consisted of four domains i.e. 1. General health with demographics and comorbidities, 2 .Spine-specific health with spine related health and neurological status, 3. Imaging with radiographic and MRI parameters and 4. Deformity type. Each domain consisted of one or two components with various factors and their respective measuring instruments. All the domains were designed as individual drivers of decision making without any hierarchy. The patient profile system strives to keep the granularity of the items to the optimal level and incorporates proper measuring instruments for quantifiable items. The developed Patient Profile was found to have an excellent content validity (I-CVI_r .78-1.00; Ave-CVI .92), appropriateness, relevance and usefulness. Conclusion: The proposed AOASD Patient Profile is the first attempt towards comprehensive evaluation of ASD patients. The profile offers a systematic approach in collecting those factors influencing the outcome of ASD management. Different combination of these factors could indicate the severity of the disease, help in patient counselling, facilitate shared decision making and post-operative risk stratification. This study opens up the avenues for further studies on usability and evaluation. Identifying groups of ASD patients with similar profiles can potentially help in designing decision making pathways.

Keywords

adult spinal deformity, classification, patient profile, consensus development, content validity, usability.

1031

P093: Balance in Action: A Case Report of Correction of Scheuermann's Kyphosis

Tibor Csákány ¹ and Hunor Nyéki ¹

¹ National Center for Spinal Disorders, Spine Surgery, Budapest, Hungary

Introduction: Scheuermann's kyphosis is one of the most frequent adult spinal deformity. Its diagnosis and adequate treatment are of great importance for the patients. In the majority of cases, surgical treatment is not necessary and conservative measures can ensure a good quality of life. However, in select cases, surgical deformity correction can be considered. Material and Methods: We present the case of a 42-year-old female patient, who experienced thoracal pain and early fatigue due to 67-degree segmental hyperkyphosis of the ThX-ThXII region secondary to Scheuermann's disease. The patient underwent an extended ThXII Pedicle Subtraction Osteotomy. Clinical and radiological data were collected. Results: The ThX-ThXII segmental hyperkyphosis was reduced by 37 degrees, the overall thoracal kyphosis and ThX-ThXII segmental hyperkyphosis were reduced to 45 and 30 degrees respectively. The original compensatory 87-degree hyperlordosis of the lumbar spine (LL) decreased to 42 degrees. This correlated with the theoretical lumbar lordosis derived from the pelvic incidence. The change in the height of the spine was 16% on standing radiographs, the patient was measured 7 cm taller. Clinically improvement in ODI, COMI, VAS scores was 53-30, 8.4-4.7, 38-78 respectively. Conclusion: After the surgical correction, the global shape of the spine became more ergonomic compared to the preoperative forced compensatory alignment. As a result of this, the patient reported decreased pain and improved physical condition.

1033

P094: Fatal Complications on 3 Dimensional Reconstruction for Degenerative Lumbar Kyphoscoliosis in an Elderly. A Case Report on Cardiovascular Complication in Spinal Correction Surgery

Takahiro Iizuka ¹ , Tetsuro Takai ¹ , Tokuji Kashiro ¹ , Toyohito Iwami ¹ , and Hiroshige Debata ¹

¹ Kouseikai Takai Hospital, Orthopaedic Spine Surgery, Nara, Japan

Introduction: Degenerative Lumbar Kypho-Scoliosis (DLS) is often challenging when surgery is required because of its pathologies which require not only decompression but also 3-dimentional correction of spinal curvature. 3-Dimentional reconstruction of spinal curvature in sagittal and coronal plane is the mainstay in recent spinal surgeries evaluating SVA,PT,PI and LL‐PI<10. We have been treated DLS patients with posterior decompression, derotation/correction of curvature and fusion technique. Benefits are often reported on correction surgery of spinal balance. In our series we experienced a case with cardiovascular complication in DLS patient. This case is considered to be related to the correction of spinal curvature. However little reports on anterior soft tissues (anterior cardiovascular) are found in literatures. Aims: 1. To report fatal risk of 3 dimensional spinal correction surgery for DLS; 2. to sound the alarm on anterior cardiovascular function. Material and Methods: A case is reported regarding risk on 3 dimensional reconstruction surgeries. Results: A Case: Cardiovascular complication with decrease of inferior vena cava blood return 74 y.o. female who diagnosed as DLS (SVA:110mm, LL:10,PI:47,PT:15,Cobb 38). She suffered intractable neural pain in both legs and disability in standing because of loss of spinal global balance. Pre-operative evaluation showed neural compression with lambar canal stenosis and pancreas cyst on MRI and CT-myelography. Surgery was aimed to decompression and correction of Kypho-scoliosis with instrumentations. Surgery was performed according to the pre-operative planed maneuver without any surgical problems throughout the surgery using autologous transfusion/intraoperative blood salvage (blood loss 800g and operation time 4.5 h). At the time of closing the skin, blood pressure was rapidly got down to 50‐60 mmHg. We suspected pulmonary embolism (PE), and quickly closed the skin with staples. CT scan showed no suspicious PE and intraperitoneal bleeding. Cardinal angiography showed Takotsubo cardiomyopathy (Left Ventricular Apical Ballooning Syndrome). The cause of rapid cardiomyopathy may be cause by surgical stress ie. Pain and Hypo-inferior vena cava blood return. In this case huge pancreas cyst and correction of spinal curvature might obstruct the inferior vena cava blood return. Conclusion: Spinal reconstruction with correction global balance is the mainstay in spinal surgeries. However, little attention is paid for anterior cardiovascular function at the planning of surgery. Correction of sagittal balance for DLS may cause the stretch of anterior soft tissues (inferior vena cava and gastro-intestinal organs). This maneuver is quite valid from the point of view ie. global spinal balance. Besides, too much correction may result in unexpected cardiovascular function at correction of DLS patients whose anterior soft tissues must be stiff. Monitoring of central vena cava pressure (CVP) may be also required at the planning of DLS correction as well as monitoring MEP.

1123

P095: Assessing Pain as a Primary Factor in the Surgical Treatment of Adult Spinal Deformity Surgery in Patients Over 60 Years of Age. A Prospective, Observational, Multi-Center Study

Colby Oitment ¹ , Stephen Lewis ² , Christopher Nielsen ² , Thorsten Jentzsch ² , Anna Rienmueller ² , Allan Martin ² , Han Shear Yashuv ² , and AO Spine Knowledge Forum AO Spine Knowledge Forum ²

¹ McMaster University, Orthopedic Surgery, Hamilton, Canada

² University of Toronto, Department of Orthopedic Surgery, Toronto Western Hospital, Toronto, Canada

Introduction: Patients with Adult Spinal Deformity (ASD) often suffer from significant pain and disability, which has been shown to improve with surgery. Nonetheless, a small proportion of patients still remain quite disabled after surgery. Most studies examining pain after deformity surgery are retrospective, include heterogeneous populations and fail to thoroughly analyze pain outside the traditional Minimally Important Clinical Differences (MCID). The purpose of this study is to utilize multi-centre, prospectively collected data to examine the effects of adult deformity surgery on multiple different Patient Reported Outcome Measures (PROMs). Materials and Methods: This study utilizes data from the Prospective Evaluation of Elderly Deformity Surgery (PEEDS) study, a multi-centre, prospective, observational trial. Leg and back pain were assessed using the respective Numeric Rating Scales (NRS), pain sub scores from the Scoliosis Research Society-22 revised (SRS-22r), Oswestry Disability Index (ODI), and the EuroQol 5-dimensions (EQ-5D). Assessments were made pre-operatively, at 10-weeks, 1-year and 2-years post-operatively. Results: Two-hundred fifty-five patients over the age of 60 were recruited from 12 centers, and 219 met inclusion criteria for analyses. The mean age was 67.5 years, 80.1% of patients were female, 56.6% were Caucasian. Most patients underwent a single posterior procedure (76.7%); 20.6% had an anterior/lateral stage 1 procedure and 2.7% had a single stage anterior/lateral and posterior procedures. Mean baseline NRS scores for back pain were worse than leg pain, with mean (SD) scores of 6.1 (± 2.7) and 4.3 (± 3.3), respectively. Both of these measures improved significantly compared to baseline at all time points (P < .001). NRS back and leg scores reduced to 2.6 (± 2.6) and 2.3 (± 2.7) at 2-years, respectively. While the majority of patients had some degree of pain in either back or leg at 2-years, 22.4% of patients on SRS-22r, 31.1% on NRS back pain, 31.4% on EQ-5D, 31.6% on ODI, and 42.4% on NRS leg pain, reported that they were pain-free. More than 20% improvement was achieved by two-thirds of patients on NRS back pain and more than half on NRS leg pain. Worse pain at 2-years compared to pre-operative values was seen in 15.1% on NRS leg pain, 5.7% on NRS back pain and was more likely to occur with lower baseline pain scores. Conclusions: This is the first international, multicenter study with prospectively collected data that assesses pain utilizing multiple outcome measures in elderly patients undergoing deformity surgery. All pain measures showed significant improvement at 1 and 2 years, that was similar for all age groups. At 2-years, roughly one third of patients were pain free. This study provides relevant information for the surgeon and patient to help inform the surgical decision making process.

1140

P096: Do We Have an Ideal System for Classifying Adult Spinal Deformity Patients? The Characteristics, Clinical Utility and Methodological Quality of Classification Systems for Adult Spinal Deformity: A Systematic Review

J Naresh-Babu ¹ , Kenny Yat Hong Kwan ² , Wilco Jacobs ³ , David Polly ⁴ , Yabin Wu ⁵ , Jong-Beom Park ⁶ , Manabu Ito ⁷ , Miranda van Hoff ⁸ , and Marinus De Kleuver ⁸

¹ Mallika Spine Centre, Guntur, India

² Queen Mary Hospital, The University of Hong Kong., Hong Kong, Hong Kong

³ The Health Scientist, Nijmegen, The Netherlands

⁴ University of Minnesota, Minnesota, USA

⁵ AO Spine, Switzerland, Switzerland

⁶ Uijeongbu St. Mary's Hospital, Gyeonggi-do, South Korea

⁷ Hokkaido Medical Center,, Sapporo, Japan

⁸ Radboud university medical center, Nijmegen, The Netherlands

Background: Adult spinal deformity is a multifactorial disease with combination of back pain, leg pain, often associated with neurological symptoms and multiple co-morbidities along with a radiological deformity. An ideal classification system should comprehensively include all these parameters, should be able to categorise similar pathologies and guide the treatment options. The purpose of this systematic review is to identify the characteristics, purpose and methodological measurement properties of available classifications for ASD. The results of this will identify the strengths and deficits of existing classifications and will also guide in identifying the factors to be included in the future ASD classifications. Methodology: 163 studies were evaluated online for the use of classification systems of ASD in their studies by searching the electronic bibliographic databases: MEDLINE, EMBASE, CINAHL, and Web of Science (Science and Social Science Citation Index) for specific terms. The results were collected and evaluated by 2 independent researchers. Risk of bias of the methodological studies was assessed with the QAREL tool. To identify the minimum standards that should be measured while managing a patient with ASD, the data points from the international expert consensus on ‘Core Outcome Set Scoliosis (COSSCO)’ risk factors for ASD developed by Scoliosis Research Society were utelised. Results: The search yielded 8447 references. After removal of duplicates, two independent reviewers reviewed 4470 abstracts. 4150 were excluded after abstract evaluation and 320 articles were retrieved for full text review. After full text review, 163 articles were included in the study. From these, 54 different classification systems were identified. The most used is the SRS-Schwab (and its predecessors), which is essentially a radiological classification. While 26 classified ‘whole spine’, others were regional (5 were lumbar and 9 each were in cervical and lumbar). 35 classifications were purely radiological whereas 7 included some clinical components. The main purpose was treatment guidance in 14, clinical diagnosis in 7, complication & risk assessment in 4 and outcome prediction in two. In 23 classifications the main purpose was not reported and rest had mixed functions. Interestingly, none of the existing classifications met all of the risk factors of COSSCO. Conclusion: This systematic review found 54 different classification systems for ASD. The availability of variety of classifications suggests that the classification systems in ASD are not standardized for universal use. There is an urgent need for a comprehensive classification system for ASD and to categorise and provide guidelines to the treatment, the classification system should ideally include all the minimum standards proposed.

1195

P097: Management of Proximal Thoracic Kyphoscoliosis with Early Myelopathy in Young Adult with Neurofibromatoisis Type 1 by All Posterior Approach

Munjal Shah ¹ , Kutbuddin Akbary ² , Priyank Patel ¹ , and Abhay Nene ¹

¹ Lilavati Hospital and Research Centre, Orthopaedic spine, Mumbai, India

² Wockhardt hospital, Orthopaedic spine, Mumbai, India

Introduction: Neurofibromatosis (NF) 1 is associated with skeletal deformities. Scoliosis is seen in about 10 to 64 % of NF1 patients. NF-1 may be associated with dystrophic or non-dystrophic type of curve. There are technical difficulties in treating large Dystrophic curve with proximal thoracic kyphoscoliosis in NF1. This case report and subsequent review of literature attempts to provide a line of management for such difficult lesions. Material and Methods: We present a case of 22-year male with NF 1 who came to us with gradually progressive upper back deformity and signs of early myelopathy since 2-3 months. Patient had a 100-degree proximal thoracic kyphosis and 100 degree scoliosis with no neurological deficit and brisk reflexes. A single stage posterior fixation with three column osteotomy at the apex of the curve was performed. Results: The Kyphosis was corrected to 65 degree from 100, the scoliosis was corrected to 60 degree from 100. Clinically, the hump in the upper back was visibly reduced. At 1 year follow up the patient remained asymptomatic with no loss of correction and implant breakage on x-ray. Conclusion: Large dystrophic proximal thoracic kyphoscoliosis are difficult lesions to treat and can be managed with an all posterior approach leading to good cosmetic and neurological outcomes, as demonstrated by this case.

1255

P098: The Influence of Multilevel Spinal Deformity Surgery on the EuroQol Five Dimensions' (EQ-5D) Questionnaire and Residential Status in the Elderly: A Prospective, Observational Multicenter Study

Thorsten Jentzsch ^1,2 , Stephen Lewis ¹ , Colby Oitment ¹ , Allan Martin ¹ , Anna C. Rienmüller ¹ , Han Shear Yashuv ¹ , Christopher J. Nielsen ¹ , and AO Spine Knowledge Forum Deformity AO Spine Knowledge Forum Deformity ³

¹ Toronto Western Hospital, University Health Network; University of Toronto, Toronto, Canada

² Balgrist University Hospital, University of Zurich, Zurich, Switzerland

³ AO Spine Knowledge Forum Deformity, Davos, Switzerland

Introduction: There is very limited studies about the clinical outcome focusing on the EuroQol five dimensions’ questionnaire (EQ-5D), which is a quick questionnaire allowing comparison with other diseases, after multilevel spinal deformity surgery in the elderly. This study aimed to investigate the clinical outcome by providing an in-depth analysis of the EQ-5D and residential status up to 2 years after ≥5 level spinal deformity surgery in the elderly. Materials and methods: As an ancillary study to the main multicenter, international prospective study of 255 patients ≥60 years with spinal deformity undergoing primary instrumented fusion surgery of ≥5 levels, this study focuses on the EQ-5D-3L as the primary outcome and residential status as the secondary outcome. Pre- and postoperative data on the EQ-5D were compared between baseline preoperatively and postoperatively at 10 weeks (±6 weeks), 1 year (± 2 months), and 2 years (±2 months). The scores were grouped into improvement from baseline (substantial (≥ 20%) and marginal (≥10-<20%)), similarity to baseline (within 10%), and decrease from baseline (marginal (≥10-<20%) and substantial (≥ 20%)). Results: The adjusted EQ-5D index and EQ VAS (95% confidence interval (CI)), respectively, increased significantly at each time point compared to preoperatively (i.e. .52 (.49-.56) and 54 (50-58) points preoperatively, .66 (.63-.69) and 65 (61-68) points at 10 weeks, .76 (.73-.80) and 74 (70-77) points at 1 year, as well as .74 (.71-.78) and 70 (66-74) points at 2 years; P < .001). The overall changes for the adjusted EQ-5D index and EQ VAS, respectively, from preoperatively to 2 years were .22 and 17 points. The EQ-5D improved in 102 (60%) patients (i.e. substantially in 80 (47%) patients and marginally in 22 (13%)), remained similar in 53 (31%), and decreased in 15 (9%) (i.e. marginally in 9 (5%), and substantially in 6 (4%)). 172 (100%) patients lived at home at 2 years. Conclusions: This study provides in-depth analysis of the EQ-5D up to 2 years after ≥5 level spinal deformity surgery in elderly patients and a comparison to the previous sparse literature regarding similar patient cohorts. The EQ-5D index was a good assessment tool in this patient cohort. It significantly increased at each time point over 2 years. Only few patients had extreme problems and substantial worsening of the EQ-5D was observed in only 4% of patients. Elderly patients can expect to live at home after multilevel surgery for spinal deformity.

Keywords

scoliosis, adult, surgery, outcome assessment, health care, residence characteristics

1267

P099: Multilevel Posterior Column Osteotomies (mPCO): Evaluation of the Technique for Lumbar Sagittal Realignment in the Unfused Disc

Joseph Osorio ¹ , Meghan Cerpa ² , James Lin ³ , Griffin Baum ⁴ , Simon Morr ² , Scott Zuckerman ² , Joseph Lombardi ² , Zeeshan Sardar ² , and Lawrence Lenke ²

¹ University of California San Diego, San Diego, USA

² Columbia University Medical Center, New York, USA

³ Mount Sinai, New York, USA

⁴ Northwell Health, New York, USA

Summary: MPCOs can aggregate large amounts of lumbar lordosis segmentally and be utilized for revision surgeries in unfused discs. We analyzed a series of ASD patients with regional and/or global sagittal malalignment who had MPCOs performed for sagittal correction. Significant improvements were seen in restoring lumbar lordosis, and no difference was seen between primary and revision settings. The MPCO technique significantly restored sagittal correction in both the primary and revision ASD patients. Hypothesis: The MPCO technique aggregates large amounts of lordosis segmentally and can be used in revision cases with unfused discs. Study Design: Single-institution, retrospective analysis. Introduction: In adult spinal deformity (ASD) surgery, multiple posterior column osteotomies (PCOs) are a useful technique, yet the potential for correction is contingent on the segment not being circumferentially fused. MPCOs can aggregate large amounts of segmental lumbar lordosis (LL), be used in primary/revision settings, and can obviate the need for invasive 3-column osteotomies (3COs). In a series of ASD patients undergoing surgeries for MPCOs, sagittal realignment and LL restoration were analyzed. Methods: A total of 98 lumbar levels from 18 consecutive ASD patients with unfused lumbar discs (70% previous surgery) treated with posterior-only surgery were analyzed. Each patient had 5 sagittal plane x-rays: preoperative standing, preoperative supine, intraoperative pre-rod insertion, intraoperative post-rod insertion, and postop standing. Sagittal Cobb angles were measured segmentally, along with L1-S1 LL. The lumbar levels analyzed were separated by operative invasiveness: prone positioning alone, MPCO, and MPCO with TLIFs. The mean preoperative SVA was 7.2cm (.1-23.3) and mean PI-LL mismatch was 30°. (1–84). Independent t-tests and ANOVA analyses were performed. Results: Revision vs primary showed no statistical difference between intraoperative LL (P = .09). Mean in situ correction of prone positioning alone vs MPCO vs MPCO+TLIF showed a significant increase in LL between each mode of operative invasiveness (P < .0001). All pts had normalized regional and global sagittal plane realignment with a significant difference in SVA (7.2 cm vs .8cm (P < .05); and improved PI-LL mismatch (30° vs 11°, P < .05) in both groups comparing standing preoperative to postoperative X-rays. Conclusion: The MPCO technique significantly restored sagittal correction and PI-LL mismatch in both the primary and revision ASD patient. Positioning, PCO, and PCO with TLIFs when utilized a multilevel sequential approach can be used to avoid 3CO in primary or revision unfused lumbar discs. Take Home Message: This study demonstrates that MPCOs have the ability to restore lumbar sagittal alignment in both primary and revision ASD patients with unfused discs, thus obviating the need for 3Cos.

1272

P100: Simultaneous Lateral Anterior Lumbar Inter Body Fusion (LALIF) Combined with Lateral Lumbar Interbody Fusions (LLIF) in the Single-Position Lateral to Treat Degenerative Scoliosis

Cristiano Menezes ¹ , Khai Lam ² , Carlos De La Torre ² , Erica Godinho ¹ , André de Oliveira Arruda ¹ , and Gustavo Carrico ²

¹ Columna Institute, Belo Horizonte, Brazil

² London Bridge Hospital, Spinal Surgery, London, United Kingdom

Introduction and Purpose: Minimally invasive spine (MIS) lateral lumbar interbody fusion (LLIF) and anterior lumbar interbody fusion (ALIF) have been used increasingly in the treatment of adult spinal deformity (ASD). We present a novel surgical approach combining lateral-anterior lumbar interbody fusion (LALIF) alongside LLIF using separate incision(s) whilst the patient is maintained in a single lateral position. The main purpose of this technique is to avoid repositioning of the patient. Materials and Methods: In a two-centre retrospective observational study, form January 2017 to August 2020, 24 patients were identified. Whilst in a lateral decubitus position, an oblique skin incision is marked over the lower abdomen. The L5/S1 LALIF is performed via a retroperitoneal approach using a table-mounted retractor. After visualisation of the disc level, a discectomy followed by endplate preparation and final insertion of an ALIF cage is carried out. Whilst in the same lateral position and under spinal neuromonitoring, routine LLIF approaches is performed via mini-open skin incision(s) to visualise and split the psoas muscle before proceeding with a discectomy, then endplate preparation followed interbody cage placement. LLIF can be performed up to 3 levels within the same skin incision. In a second staged posterior procedure performed either on the same day or few days later, the patient is turned prone and posterior fixation is carried out (open or minimally invasive) under 3D computer navigation or Robotic guidance. Patient related outcome measures (PROMS) collected preoperatively and up to 12 months postoperatively included Oswestry Disability Index (ODI), Visual Analog Scale (VAS) for both back pain (BP) and leg pain (LP) and SF-36. Results: Of the 24 patients, 15 were female, mean age 57 years (range 38-84), average length of stay was 5.3 days, mean estimated blood loos <50 mls, and duration of surgery for first stage was 67 mins (range 35-120). Five patients were treated at 2 levels (one for each approach), six at 3 levels (2 LLIF + 1 LALIF), 11 patients at 4 levels (3 LLIF + 1 LALIF) and 2 patients at 5 levels (4 LLIF + 1 LALIF). Mean statistically significant (P < .05) improvements points from pre-operative (from baseline) to last follow-up was 24.3 ± 10.1 (44.3) for ODI, 4.4 ± 1.5 (7.5) for VAS BP, 3.2 ± 2.2 (5.1) for VAS LP, and 20.3 ± 7.9 (30.8) for PCS domain of SF-36. Based on previous studies, 22 of the patients met the minimally clinically important difference (MCID) criteria for ODI, VAS BP, VAS LP and PCS. There are no significant differences in all PROMS criteria between the 2 centres. Conclusions: Combined LALIF and LLIF approaches in the single position lateral allow for a safe MIS procedure and are promising options to treat ASD. Our early analyses show improvements in all aspects of PROMS and MCID with no significant differences between centres. Further use of these techniques and longer-term follow-up will confirm their durability. Studies comparing clinical effectiveness and safety of traditional versus these MIS techniques are needed to assist in an evidence-based decision making algorithm.

1291

P101: Use of a Lenke Probe to Cannulate a Pedicle Delivers 2.5× More Load to the Patient than a Drill

Amy Claeson ¹ , Frank Schwab ² , Anup Gandhi ¹ , and David Skaggs ³

¹ Zimmer Biomet Spine, Westminster, USA

² Hospital for Special Surgery, New York, USA

³ Childrens Hospital Los Angeles, Los Angeles, USA

Introduction: Pedicle screws have been widely adopted as the anchor of choice for posterior spinal instrumentation of the thoracic and lumbar spine. Traditionally the pedicle tract has been developed by a stiff probe, such as a Lenke probe with a slight bend to help avoid perforation of the medial pedicle wall, which is protective of the adjacent spinal cord and nerve roots. Use of power with a thinner flexible drill bit to develop the pedicle tract is gaining popularity at many centers, with a potential benefits including increased safety, less force, and surgeon preservation. The purpose of this study is to assess the downward directed force of developing a pedicle tract with Lenke probe using manual force versus a thin drill bit using power. Clinical relevance is the anterior vascular structures, the esophagus, and other tissues are at risk from anterior plunging. Materials and Methods: The right and left pedicles of four cadaver torsos from T9-L5 were bilaterally cannulated with either a Lenke Probe or a power-assisted drill by two spine surgeons experienced in both manual and power assisted technique. Bilateral cannulation yielded bone quality an internal control. The drill bit attached to the power hand piece has an outer diameter of 2.4 mm and is flexible. Each torso was placed on a Jackson table. A 5kN load cell was placed under the cadaver and on top of the table to measure the vertical component of the force applied to the cadaver by the surgeon. Force data was collected at 100Hz through the duration of pedicle cannulation. Maximum force was calculated as an outcome metric. Data did not follow a normal distribution per a Shapiro-Wilk test (P < .05), therefore a Wilcoxon signed rank test determined if a difference in maximum force existed between technique, significance set to P < .05. Results: Use of a power-assisted drill transmits a mean of 2.5× less downward force through the cadaver torso compared to a Lenke probe (Figure 1). On average 21.5 ± 15.6lbf of maximum downward force was used to force the Lenke Probe through the pedicle canal, with the largest downward force at 70.5lbs. Conversely, the power-assisted flexible drill bit required 8.3 ± 4.8lbf of maximum downward force through the pedicle, with the largest downward force at 18.0lbf. It was typical to see a change in position of either the hand or the Lenke probe during cannulation, but not with the power-assisted drill (Figure 2). It was also noted that the pedicle preparation took a mean of 3× longer with manual versus power technique. Conclusion: Findings from this cadaver study demonstrate that using a Lenke probe for pedicle tract preparation exerts a maximum downward force that is on average 2.5× greater than that during use of a power-assisted drill. The maximum downward force of 70lbs on a cadaver while cannulating a pedicle with a Lenke probe is concerning. Large downward forces during pedicle tract preparation place vital structures at risk for catastrophic injury.

1303

P102: Power-Assisted Pedicle Preparation Reduces Muscle Exertion

Amy Claeson ¹ , Frank Schwab ² , Anup Gandhi ¹ , and David Skaggs ³

¹ Zimmer Biomet Spine, Westminster, USA

² Hospital for Special Surgery, New York, USA

³ Childrens Hospital Los Angeles, Los Angeles, USA

Background: Freehand techniques of pedicle preparation and screw insertion are repetitive by nature, and the duration of the task can be long, especially in deformity cases. Surgeon safety is an upmost concern. A systematic review and meta-analysis reported that 71% of surgeons experienced work-related fatigue, and 68% of surgeons exhibit generalized musculoskeletal pain, most frequently in the back (50%), neck (48%), and arms or shoulders (43%). The use of power-assisted tools may relieve surgeons of some of this musculoskeletal burden, but to what extent? Here we use surface electromyography (EMG) to quantify a surgeon’s muscle exertion during placement of pedicle screws using both freehand and power-assisted technique in a simulated surgical environment. Methods: Pedicle preparation and screw insertion using two cadaver torsos and both freehand and powered techniques was performed by one spine surgeon. Pedicles of T9-L5 vertebrae were prepped and screws inserted bilaterally using standard freehand or powered technique (n = 18 pedicles/technique). Freehand technique included development of the pedicle tract with a Lenke probe, undertapping by Ø1.0 mm, and driving Ø5.5 mm × 40 or 45 mm length pedicle screws; powered technique used a flexible drill bit that maintains tactile feedback (Ø2.0 mm), a specially designed reamer (Ø3.2 mm), and screws of matched diameter and length. EMG sensors recorded the muscle activity from eight muscle groups on the surgeon’s working side: flexor carpi radialis, extensor carpi radialis, biceps, lateral triceps, deltoid, neck extensors, upper trapezius, serratus anterior. The maximum voluntary isometric contraction (MVIC) of each muscle group was elicited prior to the experiment. Muscle exertion was recorded through all interventions of pedicle prep and screw insertion, screw insertion data presented here. Muscle exertion for each muscle group was averaged over the task’s duration and normalized by its respective MVIC, allowing comparisons between muscle groups. Accumulated muscle exertion was quantified as area under the exertion-time curve. A Shapiro-Wilk test determined data were non-parametric (P > .05), thus the natural log was taken before performing, for each outcome metric, one mixed-effects test with Holm-Sidak’s correction, to assess differences between techniques within a muscle group, and two repeated-measures one-way ANOVAs with Dunn’s correction, to assess differences within each technique and across muscle groups. Significance set to P < .05. Results: Power-assisted screw insertion technique reduced accumulated and average muscle exertion by 75-96% and 50-92%, respectively for all muscle groups. With freehand technique, the biceps exhibited the greatest average muscle exertion at 36.5 ± 3.9%MVIC, and were not significantly different from that of the neck extensors at 32.2 ± 5.1%MVIC (P > .05); the triceps and serratus anterior were least active at 6.2 ± 1.6%MVIC and 5.6 ± 4.8%MVIC, respectively. With powered technique, the upper trapezius exhibited the greatest average muscle exertion at 12.1 ± 2.8%MVIC, followed by the neck extensors at 10.7 ± 3.7%MVIC, though not significantly different (P > .05). Conclusion: Muscle exertion on the surgeon’s working side is significantly reduced during powered screw insertion. The average %MVIC of all muscle groups during powered screw insertion falls below 15% MVIC, which may reduce the risk of injury and fatigue in surgeon populations.

1305

P103: Power-Assisted Pedicle Screw Placement Decreases Pedicle Screw Wobble and Insertion Time

Amy Claeson ¹ , Frank Schwab ² , Anup Gandhi ¹ , and David Skaggs ³

¹ Zimmer Biomet Spine, Westminster, USA

² Hospital for Special Surgery, New York, USA

³ Childrens Hospital Los Angeles, Los Angeles, USA

Background: Retrospective analyses of clinical outcomes show pedicle screws placed with power-assisted instruments fail less than screws placed using freehand technique (Seehausen et al, Spine Deformity, 2015). An explanation of these findings may be found by studying screw wobble during placement, where wobble is defined as the deviation of the screw from its intended trajectory. A screw succumbing to wobble may erode the bone surrounding the defined pedicle trajectory, which may decrease screw purchase and reduce screw pullout strength. This cadaver study quantifies the mechanical efficiency of freehand versus powered pedicle screw placement by measuring both screw wobble over the duration of insertion and insertion time. Methods: Pedicle preparation and screw insertion using two cadaver torsos and both freehand and powered techniques was performed by one spine surgeon. Pedicles of T9-L5 vertebrae were prepped and screws inserted bilaterally using standard freehand or powered technique (n = 18 pedicles/technique). Freehand technique included development of the pedicle tract with a Lenke probe, undertapping by Ø1.0mm, and driving Ø5.5 mm x 40 mm or 45 mm length pedicle screws; powered technique used a flexible drill bit that maintains tactile feedback (Ø2.0 mm), a specially designed reamer (Ø3.2 mm), and screws of matched diameter and length. Inertial measurement units (IMUs) affixed to both freehand and powered drivers recorded the angular rotation of the instruments about three planes at 100Hz over the duration of screw placement. Within the angular rotation data, a LOESS filter identified the intended trajectory, and wobble was deemed the rotational deviation from that intended trajectory. Rotational data was converted to displacement data through geometrical calculations using the screw length. Wobble path length was quantified as the cumulative displacement of extraneous screw motion, wobble area as an ellipse fit to the in-plane projection of the wobble path, and insertion time as the length of the IMU recording divided by the sampling rate. Three one-way ANOVAs with multiple comparisons and Tukey’s correction assessed outcomes as a function of both technique and screw length. Significance set to P < .05. Results: Power technique significantly reduced wobble path length, wobble area and insertion time for both screw lengths compared to those of matched freehand technique (P < .05). Wobble path length of the 45mm screw using freehand technique was 53% greater (68.7 ± 13.5 mm) than the screw’s length, whereas the matched powered wobble path length was only 87% reduced (5.9 ± 3.4 mm). Powered technique reduced wobble area by 62% and 47% for 40mm and 45 mm length screws, respectively, compared to that of freehand technique (P < .05). Powered insertion time was on average 50% faster than that of freehand (P < .05). Powered insertion time did not vary with screw length (6.9 ± 1.2 s, P > .05), whereas freehand insertion time increased with screw length, 11.3 ± 2.0 s and 15 ± 2.6 s for 40 mm and 45 mm length screws, respectively (P < .05). Conclusion: Placement of pedicle screws under power is significantly faster and significantly decreases wobble, by metrics of path length and area, compared to freehand screw placement. Therefore, the use of power-assisted tools for screw placement may reduce both OR time and the propensity of screws to loosen.

1365

P104: Dynamic Anterior Scoliosis Correction in Adult Patients Really Works

Vladimir Pereverzev ¹

¹ N.N. Priorov National Medical Research Center of Traumatology and Orthopedics, Moscow, Russian Federation

Introduction: For adults, anterior scoliosis correction (ASC) is an approach for deformity correction in conditions of completed growth of the spine, which allows maintaining its flexibility. We present a group of patients with scoliotic deformity and complete growth potential or close to it, who underwent surgical treatment using dynamic ventral correction and a follow-up period of 3 months to 1 year. Material and Methods: A retrospective analysis of clinical and radiological data from 19 patients who underwent ASC from June 2019 to February 2020 was performed. All operations are performed with open access. The following groups were formed: Lenke 1–8, Lenke 3–4, Lenke 5–7, a total of 19 patients who were compared in pairs. Estimated age, the amount of deformation Doug Cobb before and after the operation, angle correction, blood loss, length of fixation, the duration of surgery, time spent in the hospital. Quality of life was assessed using the VAS scale and the SRS-22 questionnaire. Results: A total of 21 operations were performed in 19 patients. Out of 8 patients with type I according to Lenke classification, ventral fixation via thoracotomy was performed in 3 patients, in the remaining 5 cases, thoracophrenolumbotomy was required due to the extension of fixation levels below L1, and in 6 patients, double thoracotomy was performed. The number of dynamic commit levels for all types ranged from 6 to 12. There were no statistically significant differences between the groups with Lenke I and III when comparing the indicators of age, the average angle of deformity before and after surgery, the average angle of correction, and blood loss. Comparison of these parameters for Lenke III and V types showed differences in the angles of deformity after intervention and the number of fixed levels. Since the differences for the initial angle of deformity are not statistically significant, we can say that different effectiveness of treatment of scoliosis types I and III is possible, but this requires further research on more clinical material. It is assumed that type V is more "susceptible" to treatment using ASC than type III, and may have a significantly better prognosis. There were also no statistical differences between types I and V. Differences in pre-intervention angles between groups 1 and 2, 2 and 3, and post-intervention strain angles between groups 1 and 2 are not statistically significant. There were no problems associated with cord breakage, loss of correction, or hypercorrection at the observation stages, which may be due to a short observation period. The average SRS 22 score for all patients was 4.0 ± .42. VAS scores were down from 6.9 ± 1.5 to 4.4 ± 1.6 3 months after surgery, there is a significant improvement in indicators, which indicates the unconditional effectiveness of the surgical treatment. Conclusion: Anterior correction and dynamic fixation of scoliotic deformities has promising short-term results. Further research and accumulation of data on the use of ASC will allow us to assess the long-term effectiveness of the technology, develop clear indications and develop an algorithm for applying this technique.

1432

P105: Junctional Kyphosis and Junctional Failure After Multi-Segmental Posterior Cervicothoracic Fusion - A Retrospective Analysis of 64 Patients

Alex Spiessberger ¹ , Nicholas Dietz ² , Basil Grüter ³ , Justin Virojanapa ¹ , and Peter Hollis ¹

¹ Northwell Health, New York, USA

² University of Louisville, Louisville, USA

³ University of Zurich, Zurich, Switzerland

Introduction: Junction kyphosis and junctional failure (JK, JF) are known complications of thoracolumbar deformity correction. This study aims to define the incidence and risk factors for JK/JF following multi-segmental cervicothoracic fusion. Methods: This single-center retrospective analysis of 64 consecutive patients includes multi-segmental posterior cervicothoracic fusions of at least 5 motion segments with UIV in the upper cervical spine or occiput and LIV in the upper thoracic spine. A univariate analysis was performed to determine the effect of level of UIV and LIV, fusion status, C2 SVA, C2C7 lordotic angle and T1 slope angle on the occurrence of JK or JF. Results: A total of 46 patients were followed up for a median of 1.1. years (.3-4), with median age of 65.5 years (42.2.-84.5). Indication for surgery were stenosis (87%), tumor (6%) and trauma (7%). Median number of levels fused was 7. The most frequent UIV was C2 (59%), and the most frequent LIV was T2 (63%). Solid fusion was achieved in 78% of cases at last follow-up. Postoperatively, the median C2 SVA was 32 mm (−7-75), median T1 slope angle was 33° (2-57°), C2C7 sagittal cobb angle was 4° (−29°-12°). PJK developed in 4% of cases and no cases of PJF, DJK or DJF were observed. In another 4% of cases, screw loosening occurred at either LIV or UIV. No significant impact of bone density, level of UIV, level of LIV or postoperative sagittal cervical imbalance on the occurrence of JK/JF was observed, though fusion status and pathologic T1 slope angle showed a trend towards significance. Conclusion: In this cohort of patients with normal to mildly pathologic sagittal balance and bone density, JK was a rare event after long cervicothoracic fusions, observed in only 4% of cases. Neither level of UIV nor LIV had an influence on its occurrence, however non-union and pathologic sagittal alignment showed a trend towards significance.

1563

P106: Lateral Lumbar Interbody Fusion in Adult Scoliosis Patients: A Long-Term Follow-Up Study

Stuart Changoor ¹ , Conor Dunn ¹ , Nikhil Sahai ¹ , Kumar Sinha ¹ , Ki Hwang ¹ , Michael Faloon ¹ , and Arash Emami ¹

¹ St. Joseph's University Medical Center, Paterson, NJ, USA

Introduction: Adult scoliosis is often treated with large open posterior or combined anterior/posterior procedures. While successful at correction of sagittal and coronal deformities, traditional approaches can be quite morbid with high levels of post-operative complications. In order to minimize operative time, blood loss, and other complications, minimally-invasive techniques such as Lateral Lumbar Interbody Fusion (LLIF) have been used to address or supplement correction of these deformities. While there is literature on corrective outcomes, complication rates and clinical follow up of 2-years for adult scoliosis patients undergoing LLIF, there are no long-term studies assessing outcomes of these procedures. We sought to provide spine surgeons with a better understanding of the procedure by reporting long-term clinical results of LLIF procedures in adult deformity patients. The purpose of this study is to assess the long-term safety and efficacy of LLIF with posterior instrumentation in adult deformity patients. Material and Methods: Between 2008 and 2013, 34 patients with adult scoliosis treated with LLIF at a single institution were identified. Functional outcome score assessments were completed preoperatively and at each follow-up visit. Functional outcome scores included Visual Analog Scale (VAS) Back, Left and Right Leg, Oswestry Disability Index (ODI) and SRS-22. At 5-year follow-up patients were asked if they would have their surgery again, and to characterize their overall surgical outcome (Excellent, Good, Fair or Poor). 8 patients were lost to follow-up. Pre- and post-operative deformity cobb measurements were taken and medical records were reviewed for all complication sand revision procedures. Standard binomial and categorical comparative analysis were performed. Results: 26 patients were included in the study. 18 females and 8 males with a mean age of 62 (43 to 81), follow-up of 77 months (SD 19.2) and mean of 1.7 levels per operation (range 1-3). Mean deformity cobb angle was 26 degrees preoperatively and 14 degrees postoperatively, suggesting significant deformity correction. There were no intraoperative complications. There were 3 revision procedures, a proportion of 11.5%. Two revisions were due to adjacent segment degeneration and treated with extension of the posterior fusion construct. The other revision was secondary to proximal junctional kyphosis and the construct was extended as well, one year postoperatively. There were significant improvements in VAS Back, Left & Right Leg, ODI, and SRS-22 scores. At 5-year follow up, 22 (85%) patients described the result of their surgery as excellent or good. Twenty-four (92%) patients said that they would have their surgery again. Conclusion: Patients who had LLIF incorporated into the treatment of their adult scoliosis surgical correction achieved successful long-term outcomes. The amount of correction achieved was significant, while complications and revisions proportions remained low. Patients experienced significant improvements in outcome scores (ODI, VAS, and SRS-22), were highly satisfied with their treatment, and would undergo their surgical intervention again. Most importantly, our study has the longest follow-up in the literature to date, and thus we feel that LLIF provides a safe and effective treatment modality on its own or in conjunction with traditional large open adult scoliosis interventions.

1575

P107: Adult Spinal Deformity: Functional Improvement After Non-Operative Treatment? Results From an Interdisciplinary Biopsychosocial Intervention

Evelien Hoevenaars ¹ , Michiel Beekhuizen ² , John O'Dowd ³ , Maarten Spruit ² , and Miranda van Hooff ⁴

¹ Sint Maartenskliniek, The RealHealth Institute, Berg en Dal, The Netherlands

² Sint Maartenskliniek, Department of Orthopedics, Ubbergen, The Netherlands

³ Weymouth Street Hospital, London, United Kingdom

⁴ Sint Maartenskliniek, Department of Research, Ubbergen, The Netherlands

Introduction: Due to the ageing population, an increased prevalence of adult spinal deformity (ASD) exists. It is a growing burden in health care. Currently, no evidence based treatment exists for ASD patients with chronic low back pain (CLBP). An interdisciplinary intensive combined physical and psychological programme (CPPP), based on cognitive behavioural treatment principles, has been validated and proven to be effective for patients with CLBP. The aim of this study is to document the outcomes of this CPPP for ASD patients with CLBP and compare the treatment outcomes with a non-ASD cohort (CLBP patients without ASD). Material and Methods: An ASD cohort (n = 80) was selected from the database with prospectively collected data on all consecutive patients that completed the CPPP with one year follow up. Main inclusion criteria for the CPPP: no indications for surgery or invasive pain treatment, an angular (Cobb) value > 10°, CLBP for at least 6 months, age between 18 and 70 years, willingness to change behaviour, willingness to participate in a two-week programme in a hotel facility and able to speak and read the Dutch language. Exclusion criteria: involvement in litigation and/or compensation claims, and primary psychiatric disorders. This ASD cohort was matched, based on age and gender, with a non-ASD cohort (n = 240). Primary outcome measure: functional status (ODI). Secondary outcome measures: pain intensity (NPRS), self-efficacy (PSEQ) and quality of life (SF36-PCS and SF36-MCS). Assessments: pre and post treatment, 1- and 12-month follow up (FU). Improvement over time was measured with repeated measures ANOVA. Clinical relevance was determined by a predefined minimal important clinical change (MCIC) in ODI of 10 points. Patient acceptable symptom state (PASS): ODI ≤22. Results: Demographics ASD cohort: 63% female, mean age 50.9 (±14.1) years, mean CLBP duration 15.5 (±12.5) years, mean Cobb angle 21.4 (±9.4)°. The matched non-ASD cohort did not differ in demographics from the ASD cohort. The ASD cohort reported improved functional outcome at 1-year FU. Clinical relevance: 51% of the ASD patients reached MCIC and 33% reached a PASS. The improved functional outcome at 1-year FU is comparable to the non-ASD cohort F(1, 348) = .312,P > .05. All secondary outcomes followed a similar pattern: improvement at 12 month FU, with outcomes of the ASD group not being statistically significantly different from the matched non-ASD group. Conclusion: To our knowledge this is the first study showing beneficial outcomes of a non-operative treatment in ASD patients with longstanding CLBP. The CPPP achieves improvement in terms of functional status, pain, and quality of life for ASD patients for whom surgery is not an option. This could help diminish the increasing burden of ASD for patients and healthcare utilization and costs.

1658

P108: Which Frailty Scales for Patients with Adult Spinal Deformity are Used and What are Their Measurement Properties? A Systematic Review of the Literature

Kazuya Kitamura ^1,2 , Miranda van Hoff ^1,3 , Wilco Jacobs ⁴ , Kota Watanabe ² , and Marinus De Kleuver ¹

¹ Radboud University Medical Center, Orthopedics, Nijmegen, The Netherlands

² Keio University School of Medicine, Orthopaedic Surgery, Tokyo, Japan

³ Sint Maartenskliniek, Department of Research, Nijmegen, The Netherlands

⁴ The Health Scientist, Den Haag, The Netherlands

Introduction: Assessing frailty of spine surgery candidates, especially in those with adult spinal deformity (ASD), is important considering the invasiveness of spine surgery. The purpose of this study was to evaluate the use and measurement properties of frailty scales to be used in patients with spinal disorders, including ASD. Material and Methods: A systematic search in multiple bibliographic databases between January 2010 and February 2020 was performed. The search strategy included terms relating to spinal disorders, frailty scales, and methodological quality. Both clinical studies with use of frailty scales and studies that evaluate measurement properties (i.e. validity, reliability, responsiveness) of a frailty scale were included, involving adults aged ≥18 years, all spinal disorders, and a study sample of ≥10 patients. PRISMA guidelines were followed and the Risk of Bias of included studies was determined with the 11-item QAREL score for diagnostic reliability studies. Results: Of the 1006 references found, 52 studies were included. Except for one prospective comparative study, all studies were retrospective including database studies in which the prospectively collected data were analyzed retrospectively. Thirty-nine studies evaluated frailty in relation to outcomes, including complication and/or mortality risk prediction. In the remaining thirteen studies, the frailty scales were used as measures to indicate frailty prevalence. In total, seventeen frailty scales used with spinal disorders were identified. Most frequently used scale was the 11-point modified Frailty Index (mFI-11, n = 24), followed by ASD Frailty Index (ASD-FI, n = 7). Of the 39 studies that analyzed a relation to outcomes, seven studies reported measurement properties of the scales. Predictive validity of mFI-11 and Nottingham Hip Fracture Score, and construct validity of Metastatic Spinal Tumor Frailty Index, ASD-FI, and 5-point mFI (mFI-5) were evaluated. Frailty scales were used in twenty deformity populations, of which fifteen for ASD and five for cervical deformity, as well as eleven for trauma, eleven for degenerative, and ten for others. In the fifteen ASD studies, the following three scales were identified: ASD-FI (n =7); mFI-11 (n = 6); and mFI-5 (n = 2). While mFI-11 and mFI-5 consists of two domains (comorbidity and physical) covered by 11 and 5 items respectively, ASD-FI consists of five domains (comorbidity, physical, psychological, social, and others) covered by 40 items. Construct validity was evaluated for ASD-FI and mFI-5. Moderate correlation between ASD-FI and Oswestry Disability Index was indicated (Pearson correlation [r] .401). Though excellent concordance of mFI-5 with mFI-11 was shown (weighted Kappa .87), measurement properties of mFI-11 have not been reported in ASD studies. These studies were not free of bias because most of the QAREL items were scored unclear. Conclusion: No adequate frailty scale used in any spinal disorders, or in ASD specifically, was identified. ASD-FI had the most comprehensive characteristics for the risk stratification of ASD surgery candidates, but its feasibility and measurement properties remain inconclusive. We recommend evaluating the measurement properties of frailty scales in ASD populations that have been evaluated in other medical fields outside spine, such as FRAIL, Clinical Frailty Scale, Edmonton Frail Scale, Groningen Frailty Indicator, Tilburg Frailty Indicator, and PRISMA-7.

1740

P109: Trends and Complications in Spinopelvic Fixation for Deformity Amongst American Board of Orthopaedic Surgery (ABOS) Part II Candidates Over One Decade (2008-2017)

Caleb Yeung ¹ , Andrew Schoenfeld ¹ , Harry Lightsey IV ¹ , James Kang ¹ , and Melvin Makhni ¹

¹ Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA

Introduction: Complication rates for cases with pelvic fixation are widely reported in spine deformity literature but are typically derived from practices of senior surgeons. As surgical experience and clinical volume are shown to decrease complication rates, spine surgeons newly in practice may have higher risks of such events. We evaluated trends and complications following posterior spinal instrumented fusion for deformity with/without pelvic fixation using the American Board of Orthopaedic Surgery (ABOS) Part II Oral Examination Candidate Case List data from 2008 to 2017. Material and Methods: Surgical cases submitted by candidates taking the ABOS Part II Oral Examination between 2008 and 2017 whose designated subspecialty was spine were retrospectively reviewed. Mortality, readmission/reoperation data, and complications as reported by candidates were tracked over time. Bivariate testing and multivariable Poisson analyses respectively were used to assess complication rates and time-related trends. Results: A total of 37,539 cases were submitted between 2008 and 2017. 461 cases (1.2%) were for deformity; of these, 60 cases included pelvic fixation (13% of deformity cases). For all deformity cases, we noted medical, surgical and overall complication rates to be 17%, 22.3, and 31.5%. Sub-stratifying by pelvic fixation, there was no difference between those who underwent pelvic fixation and those who did not with regard to overall mortality (0 deaths vs 2 deaths, respectively; P = .584), biologic sex (68.3% female vs 62.8% female, P = .410), or anesthesia complications (1.7% vs 1.2%, P = .789). Patients who underwent pelvic fixation were significantly older (60.2 years, 95% confidence interval [CI] 32.9-37.1 years) than those who did not undergo pelvic fixation (34.7 years, 95% CI 55.6-64.4 years) (P < .001). Pelvic fixation was associated with a significantly higher reoperation rate (14.3% vs 5.3%, P = .036) and a significantly higher readmission rate (16.7% vs 7.2%, P = .049). Pelvic fixation was also associated with a higher proportion of any surgical complication (41.7% vs 19.5%, P < .001), any medical complication (28.3% vs 15.2%, P = .011), and any complication overall (50.0% vs 28.7%, P < .001). Multivariable adjusted Poisson regression analysis demonstrated a consistently low number of cases performed for deformity using spinopelvic fixation over this ten-year period. Poisson regression analyses of all spinal deformity cases demonstrated that the surgical and overall complications did not significantly change for the deformity group overall over the study period. In adjusted multivariable testing, there was no significant difference in the risk of all complications (IRR 1.2; 95% CI .9-1.6; P = .330) or surgical complications (IRR 1.4; 95% CI 1.0-2.1; P = .080) for patients receiving spinopelvic fixation compared to those who did not. Conclusion: Newly-practicing spinal surgeons consistently performed low numbers of deformity cases with relatively high complication rates which remained stable over time. Though we noted an overall low rate of mortality, we also noted a high rate of complication in spinal deformity cases in accordance with the limited available literature. As such, this data may provide insight for young spine surgeons into potential difficulties when considering spinal deformity cases, promote discussion with more senior colleagues when these cases are undertaken, and allow for more informed discussions with patients.

1804

P110: The Effectiveness of Prevention Methods of Proximal Junctional Kiphosis in the Surgical Treatment of Adult Spine Deformities

Igor Basankin ¹ , Abram Guilzatyan ¹ , Karapet Takhmazyan ¹ , and Sergey Malakhov ¹

¹ Reaearch Institute Krasnodar Regional Hospital 1, Krasnodar, Russian Federation

Introduction: According to our previous studies, correction of lumbar lordosis > 30°, postoperative PJA > 10°, and concomitant osteoporosis are statistically significant risk factors for the development of PJK in surgically treated adult spinal deformities. There are many methods of preventing PJK described in literature, but their effectiveness is still controversial. Materials and Methods: The results of surgical treatment of 140 patients with lumbar spine deformities were analyzed. The inclusion criteria were: adult patients under 66 years with deformities of the lumbar and thoracolumbar spine M.Aebi I and IIIb (T-score less than −2.5). The exclusion criteria were: gross deformities with an SVA displacement anteriorly by more than 15 cm, presence of a frontal imbalance over 5 cm, preoperative PJA > 10°. All patients were divided into 4 groups: Group 1-36 patients, with partial restoration of balance due to the correction of lumbar lordosis < 30° without PJK prevention methods. Group 2-24 patients similar to group 1 with laminar fixation of the vertebra over the fusion level. Group 3-20 patients with complete restoration of the sagittal and frontal balance due to the correction of lumbar lordosis > 30 ° with vertebroplasty upper UIV. Group 4-60 patients similar to group 3, without vertebroplasty. These patient groups were analyzed according to the main clinical and radiological parameters before surgery, as well as after 3, 6, 12, and 24 months using nonparametric statistical methods. Results: The highest incidence of PJK was found in patients of group 4 (n = 19-32%). This indicator significantly differed from indicators of 1 (n = 8-22%), 2 (n = 1-4%) and 3 (n = 4-20%) groups (P < .05). Analysis shows that occurrence of PJK in most cases the was due to a fracture of the upper UIV (n = 17-53%). Another significant cause of PJK was a UIV fracture, which was detected among all groups in 7 cases (22%), without significant differences between the groups (P = .454). These fractures occurred in patients without UIV augmentation. In patients of the second group, operated with laminar fixation, there was a significant decrease in PJA after surgery by an average of 5° (P = .001). Laminar fixation in combination with partial correction of lumbar lordosis up to 30° decreases the frequency of its occurrence to 4% (P < .05). Vertebroplasty of upper UIV in group 3 patients with lumbar lordosis correction of more than 30° reduced the number of PJK cases to 20% (P < .05). The number of PJK cases in group 3 was 37.5% lower than in the group 4 without vertebroplasty. Conclusion: Partial correction of lumbar lordosis up to 30° in combination with laminar fixation of the adjacent vertebra was effective method for preventing of PJK. In the case of lumbar lordosis correction of more than 30°, it is advisable to use upper UIV vertebroplasty to reduce the incidence of PJK.

1884

P111: Quality of Life in the Elderly with Spinal Deformity in Pandemic Times

Maria Luz Suarez-Huerta ¹ , Alejandro Gomez-Rice ¹ , Iria Carla Vazquez-Vecilla ¹ , Cristina Madrid De La Serna ¹ , and Lorenzo Zuñiga-Gomez ¹

¹ Hospital Universitario de Getafe, Madrid, Spain

Introduction: As we already know, on December 31, 2019, the Authorities of the People's Republic of China reported several cases of pneumonia of unknown etiology to the OMS in Wuhan. On March 11, 2020, the OMS recognized the situation generated by SARS-CoV-2 as a global pandemic. At present, the number of confirmed cases is 34,804,348 million in the world, 5,763,740 cases in Europe and 813,412 cases in Spain, being the second country in Europe with the highest number of confirmed cases. In Spain, the community of Madrid has the highest number of diagnosed patients with 257,708 confirmed cases. This infection is especially affecting the older population, because it is the most vulnerable and develops more serious processes. These people are especially afraid of contagion and have a tendency to isolation, which is associated with a tendency to depression. Material and Methods: Observational, longitudinal, transversal study of patients who underwent transpedicular arthrodesis surgery in adult deformity at the Getafe hospital (South of Madrid) from 1 January 2010 until 31 December 2015. We collected sociodemographic variables, diagnosis, type of surgery, arthrodesis levels, complications and scores of quality of life (SRS, SF12, EQ5, GDS and Barthel). The data were collected during the state of health alarm. We did a statistical analysis using SPSS software v22.0Our objective is to know the incidence of COVID and the quality of life of our vulnerable patients in a pandemic. Results: We have included 60 patients, 83 % were women, the mean age was 76 years and levels fused 8. Our patients have a tendency to depression (GDS 5.8 ± 3) and mild dependence (Barthel 91 ± 15). 27% have died a family member in recent months. 78.3% report being afraid to go to the Hospital. The SF-12 preoperative PCS-12: 23.2 ± 5 and MCS-12: 52 ± 11 to the postoperative PCS-12: 32 ± 9 and MCS-12: 46 ± 13. SRS-22 preoperative 2.5 ± .4 to postoperative 3 ± .8. EQ-5 at the current time 55%. The incidence of COVID in our patients was 8.3%, being more frequent in men (P = .002). These patients have more fixed levels (9) and have a higher consumption of medications (15). Conclusion: Our patients are especially vulnerable, they have a higher incidence of COVID than the general population and a tendency to depression.

1966

P112: Variability in Surgical Approach in the Treatment of Elderly Patients Undergoing Primary Spinal Deformity Surgery

David Polly ¹ , Sigurd Berven ² , Yong Qiu ³ , Lawrence Lenke ⁴ , Michael Kelly ⁵ , Christopher Shaffrey ⁶ , Benny Dahl ^{7 8} , Marinus De Kleuver ⁹ , Maarten Spruit ⁹ , Ferran Pellisé Urquiza ¹⁰ , Kenneth Cheung ¹¹ , Ahmet Alanay ¹² , Jonathan N. Sembrano ¹ , Yukihiro Matsuyama ¹³ , and Stephen Lewis ¹⁴

¹ University of Minnesota, Minneapolis, USA

² University of California, San Francisco, San Francisco, USA

³ Drum Tower Hospital of Nanjing University Medical School, Nanjing, China

⁴ Columbia University Medical Center, New York, USA

⁵ Washington University School of Medicine, St Louis, USA

⁶ Duke University, Durham, USA

⁷ Baylor College of Medicine, Houston, USA

⁸ National University of Denmark, Copenhagen, Denmark

⁹ Radboud University Medical Center, Nijmegen, The Netherlands

¹⁰ Hospital Universitari de la Vall d’Hebron, Barcelona, Spain

¹¹ The University of Hong Kong, Hong Kong, China

¹² Acibadem Mehmet Ali Aydinlar University, Istanbul, Turkey

¹³ Hamamatsu University School of Medicine, Hamamatsu, Japan

¹⁴ University of Toronto, Toronto, Canada

Introduction: Significant variation exists in the surgical approach to adult spinal deformity surgery. The purpose of this review is to determine whether there is a consistent approach to the surgical management of these patients.Methods: A prospective international multicenter study was performed to determine the value of surgery in patients over the age of 60 years undergoing primary fusions of 5 or more levels for degenerative or idiopathic spinal deformity. Surgeons were free to determine a patient’s candidacy for surgery as well as the surgical approach utilized. Results: 219 of the 255 patients enrolled from 12 centers met the criteria for inclusion in the study. There were 176 females and 43 males with a mean age of 67.5 (range 60-83 years). The median number of levels fused was 9 (range 5-24). 53/219 (24%) cases had 2 stage procedures with the remaining 166 (76%) having a single approach. Of the single stage procedures, there were 156 (94%) posterior procedures with the addition of TLIF in 69 (42%), PLIF in 21 (13%), and ALIF or XLIF in 4 (2%). Anterior-only procedures were performed in 4 (3%). Of the staged procedures, in stage 1 there were 4 (8%) posterior procedures, 1 (2%) PLIF, 9 (17%) ALIF and 39 (74%) direct lateral and stage 2 consisted of 39 (74%) posterior procedures, 29 (55%) PLIF, 7 (13%) TLIF, 49 (92%) PSF, and 2 (4%) anterior instrumentation. For the direct lateral, one level was performed in 3, 2-level in 23, 3-level in 6, and 4-level in 7 patients. Median operative time was 335 minutes (range 74-705) in stage 1, 320 min (200-484) in stage 2, and overall 407 min (117-878). Conclusions: While single staged posterior with or without interbodies was the most prevalent approach (73%), significant variation exists in the surgical treatment of patients over 60 years of age undergoing primary spinal deformity surgery. Further work to determine the approaches that maximize outcome is required, to better guide surgical treatment for these patients.

Degenerative Cervical

14

P113: Modified Kurukawa Cervical Laminoplasty Using Iliac Crest Bone Grafts As Spacers—Why Do It Any Other Way?

Aashish Ghodke ¹ , Davinder Bhachu ¹ , Birender Balain ¹ , and David Jaffray ¹

¹ Robert Jones & Agnes Hunt Orthopaedic Hospital, Spinal Disorders, Oswestry, United Kingdom

Introduction: The spinous process splitting laminoplasty was described by Kurukawa in 1982, although the procedure has number of theoretical and practical advantages over the Hirabayashi technique it has not been widely used because of the technical difficulties. The theoretical advantage of laminoplasty is that it can preserve stability of the cervical spine preventing postoperative kyphosis which can be seen after laminoplasty, and at the same time, it can preserve motion preventing adjacent segment diseases observed as late sequelae after anterior or posterior fusion surgery. For laminoplasty to be an ideal option to classic laminectomy and anterior decompression and fusion, it must prove to be better than laminectomy in preventing instability and kyphosis, and better than anterior fusion in preserving cervical ROM. Earlier laminoplasty techniques did not preserve the dynamic stability of the extensor muscles and failed to show superiority over other techniques. Laminoplasty as described in our study, showed similar neurological improvement to other studies but by preserving the muscle attachments at C2 and C7 and early postoperative mobilization, showed better stability and better-preserved ROM in comparison to earlier studies. Modifications of Kurukawa cervical laminoplasty technique done by the senior author includes splitting spinous process in the midline with a burr, preserving muscle attachments at C2 and C7, use of iliac crest graft as spacer rather than any expensive implants and a rigorous postoperative neck ROM exercise regimen. Effectiveness and safety profile for this technique has been evaluated prospectively. Material and Methods: 44 patients with multilevel compressive cervical myelopathy treated in this way with a mean FU of 1.4 years. PROM’s, radiological & clinical parameters and complications were evaluated. Results: Impressive increases were seen in AP canal dimensions, which persisted. Mean mJOA score improved from 11.1 to 13.4 with a recovery rate of 34%. Nurick grade improved from 3.9 to 2.7 and NDI improved by 15%. The mean C2-C7 lordosis angle changed from 18.5° to 12.0° only, with 3 patients having loss of lordosis of 20 degrees or more, two clinically doing well and one patient needing ACDF for worsening myelopathy, C3/4 instability and pain. Only one more patient had neck pain and stiffness. 4 patients had a C5-palsy, two improved to Grade 5 and two to Grade 4. None of the 22 patients had a concomitant foraminotomy at multiple levels had a C5 palsy. No patient had a flat neck deformity. The average operated levels were 3.36 per case. There were a total of 296 hinges created, with 90.5% fully united. 20 (6.8%) were ununited, but un-displaced. 2.7% hinges were displaced with no clinical concerns. One patient with a loose C5 hinge developed a Left C5 palsy 36 hours post operatively despite no compression identified on MRI scan. Conclusion: This technique provides excellent clinical and radiological outcomes, and is a safe and inexpensive way to achieve a good result with a good functional ROM.

31

P114: How Common is Repeat Surgery and Multi-Level Treatment in Degenerative Cervical Myelopathy? Findings from a Patient Perspective Survey

Ben Grodzinski ¹ , Aref-Ali Gharooni ² , Benjamin Davies ² , and Mark Kotter ²

¹ University of Cambridge, School of Clinical Medicine, Cambridge, United Kingdom

² University of Cambridge, Academic Neurosurgery Unit, Department of Clinical Neurosurgery, Cambridge, United Kingdom

Introduction: Degenerative Cervical Myelopathy (DCM) is a common condition which causes significant disability and reduces health-related quality of life. The only evidence-based treatment and current management guidance is surgery to decompress the spinal cord and stop further damage in moderate to severe cases. However, this guidance is mainly informed by studies that only include first time surgery and/or single level disease, but DCM can reoccur after primary surgery and affect multiple levels of the spine. It is unclear whether patients in these subgroups; repeat surgery and multi-level DCM, differ significantly in their baseline and disease characteristics from those with single-level, single-operation disease. Material and Methods: To investigate this, we conducted an online survey of people with DCM looking at key demographic, disease (e.g. mJOA) and treatment characteristics. Results: We received a total of 778 respondents, of which 159 (20%) had undergone surgery for DCM. Around 75% of these respondents had a single operation and 65% at a single level. We found no statistically significant difference in key participant and disease characteristics between respondents with single-level or single-operation and those with multi-level DCM or multiple operations. Conclusion: These data support generalisability of research to these subgroups but also warrants further investigations as these subgroups are underrepresented in current research.

39

P115: The Effect of Ageing on Presentation, Management and Outcomes in Degenerative Cervical Myelopathy: A Systematic Review

Ben Grodzinski ¹ , Rory Durham ¹ , Oliver Mowforth ² , Daniel Stubbs ³ , Mark Kotter ² , and Benjamin Davies ²

¹ University of Cambridge, School of Clinical Medicine, Cambridge, United Kingdom

² University of Cambridge, Academic Neurosurgery Unit, Department of Clinical Neurosurgery, Cambridge, United Kingdom

³ University of Cambridge, University Department of Anesthesia, Department of Clinical Medicine, Cambridge, United Kingdom

Introduction: Degenerative cervical myelopathy (DCM) is a disabling neurological condition. The underlying degenerative changes are known to be more common with age, but the impact of age on clinical aspects of DCM has never been synthesised. The objective of this study is to determine whether age is a significant predictor in three domains—clinical presentation, surgical management, and post-operative outcomes of DCM. Material and Methods: A systematic review of the Medline and Embase databases (inception to 12th December 2019), registered with PROSPERO (CRD42019162077), and reported in accordance with PRISMA guidelines, was conducted. The inclusion criteria were full text articles in English, evaluating the impact of age on clinical aspects of DCM. Results: The initial search yielded 2420 citations, of which 206 articles were eventually included. Age was found to be a significant predictor in a variety of measures. Within the presentation domain, older patients have a worse pre-operative functional status. Within the management domain, older patients are more likely to undergo posterior surgery, with more levels decompressed. Within the outcomes domain, older patients have a worse post-operative functional status, but a similar amount of improvement in functional status. Due to heterogenous data reporting, meta-analysis was not possible. Conclusion: The current evidence demonstrates that age significantly influences the presentation, management and outcomes of DCM. Whilst older patients have worse health at all individual timepoints, they experience the same absolute benefit from surgery as younger patients. This finding is of particular relevance when considering the eligibility of older patients for surgery.

40

P116: Research activity amongst DCM research priorities

Ben Grodzinski ¹ , Harry Bestwick ¹ , Faheem Bhatti ¹ , Rory Durham ¹ , Maaz Khan ¹ , Celine Partha-Sarathi ¹ , Jye Quan Teh ¹ , Oliver Mowforth ² , Mark Kotter ² , and Benjamin Davies ²

¹ University of Cambridge, School of Clinical Medicine, Cambridge, United Kingdom

² University of Cambridge, Academic Neurosurgery Unit, Department of Clinical Neurosurgery, Cambridge, United Kingdom

Introduction: Degenerative Cervical Myelopathy (DCM) is a progressive neurodegenerative disorder. DCM is common (estimated prevalence 2% of adults) and significantly impacts patient quality of life. The AO Spine RECODE-DCM (Research Objectives and Common Data Elements in DCM) project has recently established the top 26 research priorities for DCM, to accelerate knowledge discovery that can improve clinical outcomes. This article examines the extent to which existing research activity aligns with the established research priorities. Material and Methods: A systematic review of MEDLINE and Embase for “Cervical” AND “Myelopathy” was conducted following PRISMA guidelines. Full-text papers in English, exclusively studying DCM, published between January 1, 1995 and August 08, 2020 were considered eligible. Extracted data for each study included authors, journal, year of publication, location, sample size, and study design. Each study was then analysed for alignment to the established research priorities. Results: 2261 papers with a total of 1323979 patients were included. Japan published more papers (625) than any other country. 2005 (89%) of 2261 papers were aligned to at least one research priority. The alignment of papers to the different research priorities was unequal, with 1060 papers on the most researched priority alone (#15, predictors of outcome after treatment), but only 64 total papers on the least-researched 10 priorities. The comparative growth of research in the different priorities was also unequal, with some priorities growing and others plateauing over the past 5 years. Conclusion: Research activity in DCM continues to grow, and the focus of this research remains on surgery. The established research priorities are not well aligned with past or current research. This paper serves as a foundation for future research – both to indicate the key areas on which to focus, and as a baseline for future comparison.

76

P117: Determinants of Quality of Life in Degenerative Cervical Myelopathy: A Systematic Review

Yuri Hirayama ¹ , Mark Kotter ¹ , Oliver Mowforth ¹ , and Benjamin Davies ¹

¹ University of Cambridge, Division of Neurosurgery Department of Clinical Neurosciences, Cambridge, United Kingdom

Introduction: Degenerative cervical myelopathy (DCM) is the most common cause of spinal cord impairment worldwide. It is a chronic, progressive condition of symptomatic spinal cord compression secondary to a range of degenerative spinal pathologies. Patients experience substantial pain, functional neurological decline and disability. Health-related quality of life (HRQoL) appears to be particularly poor, even when compared to other chronic diseases. The determinants of HRQoL are poorly understood. The objective was to perform a systematic review of the determinants of quality of life of people with DCM. Methods: A systematic review was conducted in MEDLINE and Embase following PRISMA guidelines. Full-text papers in English, exclusively studying DCM, published before 26 March 2020 were eligible for inclusion. Study sample characteristics, patient demographics, cohort type, HRQoL instrument utilised, HRQoL score, and relationships of HRQoL with other variables were assessed. Results: A total of 1176 papers were identified; 82 papers were included in the final analysis, of which 93% studied surgical cohorts and 82% utilised the 36-Item Short Form Survey (SF-36) as a measure of HRQoL. HRQoL determinants were grouped into 9 themes: surgery; peri-operative management; patient experience post-surgery; cervical alignment, balance and range of motion; radiological characteristics of the spinal cord; functional disability and severity of DCM; demographics; co-morbidities and biochemistry. The most common determinant to be assessed was surgical technique (46%) followed by patient satisfaction and experience of pain (13%). HRQoL appeared to improve after surgery. Pain was a negative predictor of HRQoL. Conclusion: Quality of life of people with DCM appears to be poorer in those with more pain and to improve following decompressive surgery. Greater standardisation in DCM research is needed for further synthesis and studies of greater precision are needed to account for HRQoL being complex, multi-factorial and both time and

Keywords

cervical cord; myelopathy; spondylosis; stenosis; disc herniation; ossification posterior longitudinal ligament; degeneration; disability; recovery; quality of life

Funding

MRK gratefully acknowledges support by the Cambridge NIHR Brain Injury MedTech Cooperative and is funded by a NIHR Clinician Scientist Award CS-2015-15-023. BMD is supported by a Royal College of Surgeons Research Fellowship and an NIHR Clinical Doctoral Research Fellowship.

Disclaimer

This report is independent research arising from a Clinician Scientist Award, CS-2015-15-023, supported by the National Institute for Health Research. The views expressed in this publication are those of the authors and not necessarily those of the NHS, the National Institute for Health Research or the Department of Health and Social Care.

117

P118: Clinical Outcomes of Posterior Cervical Discectomy and Foraminotomy: Long Term Results

Gulden Demirci Otluoglu ¹ , Onder Ertem ² , Zafer Orkun Toktas ¹ , and Deniz Konya ¹

¹ Bahçeşehir University School of Medicine, Neurosurgery, Istanbul, Turkey

² Bahçeşehir University School of Medicine, Istanbul, Turkey

Introduction: Posterior cervical discectomy and foraminotomy is an appropriate surgical option in the treatment of cervical radiculopathy to the anterior cervical discectomy and fusion. Its major advantages are direct decompression of the nerve root and no need for fusion. In this study we present the descriptive data and the clinical outcomes of our patient population. Material and Method: The patients whom operated in Bahçeşehir University School of Medicine Department of Neurosurgery between the dates November 2013 and June 2020 by two senior spinal surgeons were searched for this study. Two hundred and three patients were recruited from the database. Of these 203 patients 101 of them excluded due to lack of 2-year-follow up period. Post-operative Odom scales were assessed at 1 month follow up appointment. Results: After the exclusion of the patients who do not full-fill the follow-up criteria there were 102 patients in the study group. There were 43 female and 59 male patients in the study group. The mean age was 41 (range: 22-73). Twelve patients had multilevel surgery and 90 patients had single level surgery. Of the 114-disc levels operated; 2 (1.75%) were C3-4 level; 9 (7.89%) were C4-5 level; 34 (29.8%) were C5-6 level; 65 (57%) were C6-7 level and 4 (3.5%) were C7-T1 level. The mean pre-operative cervical lordosis angle was 10.2 (range: 1-39). Of 102 patients; pre-operative ASA scores were: 1 in 46 (45%) patients; 2 in 52 (50.9%); 3 in 3 (2.94%) and 4 in 1 (.98%) patients. The mean surgery time was 59 minutes (range: 34-122 minutes). Post-operative Odom Scores were excellent in 34 patients; good in 43 patients; mean in 19 patients and bad in 6 patients. Two patients (1.9%) had revision surgery via an anterior approach with fusion. The mean follow-up time in the post-operative period was 49 months (range: 73-24). Conclusion: Posterior cervical microdiscectomy and foraminotomy can be an alternative treatment modality for anterior cervical discectomy and fusion surgery in the selected patient population with high patient satisfaction and low re-operation rates.

153

P119: A Bibliometric Analysis and Visualization of Current Research Trends in the Treatment of Cervical Spondylotic Myelopathy

Mengchen Yin ¹ , Chongqing Xu ¹ , Junming Ma ¹ , Jie Ye ¹ , and Wen Mo ¹

¹ Department of Orthopaedics, LongHua Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China

Introduction: Cervical spondylotic myelopathy (CSM) has become the most common cause of spinal cord dysfunction. Many topic of CSM still remains controversial. This study aimed to illustrate the overall knowledge structure, and development trends of CSM, using a bibliometric analysis and newly developed visualization tools. Materials and Methods: Research datasets were acquired from the Web of Science (WOS) database and the time span was defined as “2000-2019”. VOS viewer and Citespace software was used to analyze the data and generate visualization knowledge maps. Annual trends of publications, distribution, H-Index status, co-authorship status and research hotspots were analysed. Results: 2367 publications met the requirement. The largest number of articles was from USA, followed by Japan, China, Canada and India. The highest h-index was found for articles from USA. The highest number of articles was published in SPINE. The cooperation between the countries, institutes and authors were relatively weak. Cervical sagittal alignment, predictive factor, diffusion tensor imaging and the natural history of CSM may become a frontier in this research field. Conclusion: The number of publications showed an upward trend with a stable rise. Most of publications are limited to a few countries and institutions with relatively weak interaction. USA, Canada, Japan, China and India have made significantly contribution to the field of CSM. USA is the country with the highest productivity, not only in quality, but also in quantity. Cervical sagittal alignment, predictive factor, diffusion tensor imaging and the natural history of CSM are the research hotspots in the recent years.

195

P120: Top 10 Research Priorities for Degenerative Cervical Myelopathy - Results from an International Consensus Process: AO Spine RECODE-DCM

Benjamin Davies ¹ and Mark Kotter ¹

¹ University of Cambridge, Cambridge, United Kingdom

Introduction: Degenerative cervical myelopathy (DCM) is a common condition, which despite treatment, will leave most with disabilities: research progress is urgently needed to improve outcomes. Research targeted to the priorities of those working and living with a disease is demonstrated to accelerate practice changing research. These are unknown in DCM. The James Lind Alliance (JLA) is an organisation founded to coordinate and quality assure priority setting initiatives. AOSpine RECODE-DCM [Research Objectives and Common Data Elements for Degenerative Cervical Myelopathy] includes a JLA priority setting initiative for DCM, led by the AOSpine Spinal Cord Injury Knowledge Forum to identify the top 10 unanswered research questions (‘research priorities’) in DCM. Material and Methods: AOSpine RECODE-DCM is a JLA priority setting initiative. The published protocol is found here (doi: 10.1177/2192568219832855). In short, two iterative online surveys and a face to face consensus meeting were used to establish consensus. Perspective was sought from three key stakeholder groups: spinal surgeons, people with DCM (PwCM) and other health care professionals (OHP). The first survey gathered research ideas, using subcategories of diagnosis, management, long-term care and miscellaneous. Ideas were reviewed, and thematically categorised into summary questions. Answered questions identified through evidence checking were excluded. In the second survey, respondents shortlisted their top 10. The top questions were then discussed and ranked at a face-to-face consensus meeting (New York, November 2019) to generate a final list of top 10 priorities. The process was overseen by a multi-stakeholder, international steering committee. Results: 429 participants (59% Surgeons, 21% PwCM and 20% OHP) submitted >3500 research suggestions. 74 unanswered summary questions were shortlisted by 417 participants (56% Surgeons, 26% PwCM and 23% OHP). 26 questions were discussed and ranked at the consensus meeting. The final top-10 included novel diagnostics, surgical decision making, adjuvant management, understanding mechanisms and developing novel therapies. The number one priority was increasing awareness. A full list of priorities is available at https://aospine.aofoundation.org/research/recode-dcm/priorities. Conclusion: AOSpine RECODE-DCM has established the top research priorities for DCM. These objectives should be a focus for the field, to accelerate advances in care that change outcomes. The AOSpine RECODE-DCM project continues with a number of other objectives, to develop a DCM research toolkit that can help researchers changes outcomes sooner. More information at (aospine.org/recode).

203

P121: Castleman's Disease in the Sub Axial Cervical Spine: A Rare Cause of Myelopathy

Nandan Marathe ^1,2 , Abhinandan Reddy Mallepally ¹ , Gurdip Das ³ , and Kalidutta Das ¹

¹ Indian Spinal Injuries Centre, Spine Services, New Delhi, India

² Toronto Western Hospital, Orthopedic Surgery, Toronto, Canada

³ AIIMS Bhubaneswar, Orthopaedic Surgery, Bhubaneswar, India

Introduction: Castleman’s disease is a rare lymphoproliferative disease of unknown origin, rarely affects the spine. We present a case of Castleman disease that manifested as a paraspinal mass extending into spinal canal in upper subaxial spine and mimicking a metastatic secondaries or lymphoma. Materials and methods: Case report: A 52/M presented with complaints of progressive lower limb weakness, instability of gait and loss of dexterity in both hands over a period of 2 weeks. MRI, X-ray and CT scans revealed destructive lytic lesion of C3 vertebrae involving both anterior and posterior elements. Results: Patient underwent posterior instrumented decompression by C3 laminectomy and partial laminectomy of C4. A novel three-rod construct was utilized to provide additional stability involving C2 pedicle screws and laminar screw and lateral mass fixation of C4 and C5. Histopathological showed lympho-proliferative disorder with follicles of different size with abnormal germinal structures at their centres. The Mantle zone was expanded with concentric layering with an “onionskin” appearance. The final diagnosis was Castleman’s disease of hyaline-vascular type. 2-year follow-up shows complete remission of the lesion. Conclusion: Castleman’s disease is a diagnosis of exclusion that spine surgeons should be aware of. It has treatment and follow-up implications that differ from the neoplasms that it can mimic. Screening for concurrent and future malignancies is prudent.

Keywords

Castleman’s; lymph node; cervical spine; myelopathy

Bibliography

1. Gianaris PG, Leestma JE, Cerullo LJ, Butler A. Castleman’s disease manifesting in the central nervous system: case report with immunological studies. Neurosurgery 1989;24:608–612. DOI:10.1227/00006123-198904000-00021

2. Alper G, Crumrine PK, Hamilton RL, et al. Unusual case of inflammatory spinal epidural mass (Castleman syndrome). Pediatr Neurol 1996;15:60–2. doi: 10.1016/0887-8994 (96) 00090-2

3. Eisenstat R, Price D, Rosenthal A, et al. Thoracic epidural Castleman’s disease. AJR Am J Roentgenol 2002;178:208–10. doi: 10.2214/ajr.178.1.1780208

4. Kachur E, Ang LC, Megyesi JF. Castleman’s disease and spinal cord compression: case report. Neurosurgery 2002;50:399–403. doi: 10.1097/00006123-200202000-00031

5. Lee HY, Lee SH, Kim SN. Castleman’s disease: unusual case of inflammatory spinal dorsal epidural mass: case report. Neurosurgery 2002;50:396–8. doi:10.1097/00006123-200202000-00030

6. Finn MA, Schmidt MH. Castleman disease of the spine mimicking a nerve sheath tumor. Case report. J Neurosurg Spine 2007;6:455–9. doi:10.3171/spi.2007.6.5.455

7. Gupta A, Kumar L, Karak A, Thulkar S, Rastogi R, Bhatti S. Multicentric hyaline vascular type Castleman disease presenting as an epidural mass causing paraplegia: a case report. Clin Lymph Myeloma 2009;9:250–3.; doi: 10.3816/CLM.2009.n.050

8. McMillan R, Goodwin CR, Hsu W, Pendleton J, McCarthy E, Wolinsky JP, Belzberg AJ. Castleman disease of the sacral spine. Clin Neurol Neurosurg. 2012 Apr;114(3):287-9. doi: 10.1016/j.clineuro.2011.10.033. Epub 2011 Nov 21.

249

P122: Do the Quality of Life Questionnaires Reflect the Reality of the Results of Cervical Myelophaty Surgery?

Marta Esteban Blanco ¹ , Manuel Fernandez ¹ , Julio Villar Perez ¹ , Domingo Lombao Iglesias ² , Jesus Betegon Nicolas ¹ , Andrés Blanco Hortas ² , Ana Lozano Muñoz ¹ , Leticia Gallego Diez ¹ , and Jose Hernandez Encinas ¹

¹ Hospital of Leon, Leon, Spain

² Hospital of Lugo, Lugo, Spain

Introduction: Overall frequency of cervical pain is around 34%. In this study, we aim to assess the progression of disability in patients who underwent surgery due to degenerative cervical myelopathy (DCM). Material and Methods: Prospective analysis of a cohort of patients who had undergone surgery since 2015 due to cervical myelopathy. We collected demographic data and their health-related quality of life was assessed using the specific Neck Disability index. Student’s t-test was used for statistical analyses. Results: 37 patients were included in the study, median age was of 54.96 years (±10.98), bleeding of 405.83 (±220) cc, an average BMI of 27.2 (±3.99), 135.15 (±36.65) minutes of average surgical time. A total of 30 patients completed all the questionnaires at 2 years of follow-up, with a minimum follow-up of one year, the patients were found to have an average disability of 49.72 (±8.13) and the next the values were: six weeks 40.58 (±21.63), 6 months 39.62 (±20.78), one year 47.14 (±20.61). We did not find statistically significant differences between the pre-surgery with year, but yes at 6 weeks (P = .008) and at 6 months (P = .000). Conclusion: The initial disability of the patients improves over the first six month post-intervention. However, after one year, they are in the same situation as before the surgery, although improvement is observed particularly regarding headache and concentration (P = .000). Considering these results, is it possible that cervical myelopathy surgery instead of improving the progression values in comparison with the preoperative status, no clinical progression occurs as observed in this study, and consequently no clinical worsening?

293

P123: Functional Outcome in Surgically Managed Patients of Ossified Posterior Longitudinal Ligament of Cervical and Dorsal Spine—A Single Center Retrospective Analysis

Sudhir Srivastava ¹ , Manojkumar Gaddikeri ¹ , Aditya Raj ¹ , Sunil Bhosale ¹ , and Atif Naseem ¹

¹ King Edward Memorial Hospital, Orthopaedics, Mumbai, India

Introduction: Ossified Posterior Longitudinal Ligament (OPLL) is an emerging cause of compressive myelopathy in Indian subcontinent. With more and more new cases being diagnosed everyday, the treatment aspect remains in a dilemma. Patients are being managed by both conservative and operative methods. The purpose of this study is to retrospectively evaluate the functional results in operated patients of OPLL of cervical and/or dorsal spine using modified Japanese Orthopaedic Association (mJOA) score as our tool. Material and Methods: Forty patients of cervical and /or dorsal spine ossified posterior longitudinal ligament who underwent surgical intervention were included in the study. Neurological examination was conducted and analysed using mJOA score pre and post operatively at one, six and twelve months. Improvement in the mJOA score based on type of OPLL, duration of symptoms, type of surgical procedure and occupancy ratio were calculated. Results: Significant improvement in mJOA scores with mean preoperative being 12.27 ± 1.95 with one year post-operative 13.85 ± 2.02 (P value < .0001) noted. There is significant difference in mean mJOA scores in posterior approach with instrumentation (P < .0001) as compared with non-instrumented group (P < .005). Patients with occupancy ratio < 60% had better results (P < .0001) as compared to those with occupancy ratio of > 60% (P- .003). Patients with duration of symptoms >1year had poorer results compared to those with symptoms of <1year duration. Mean ossification kyphosis angle was 19.4 ± 5.73 degrees. Conclusion: OPLL is a progressive disease which causes compressive myelopathy and severe neurological deficit if left untreated. OPLL managed early and surgically have better results irrespective of anterior or posterior approach with significant improvement in mJOA scores. Patients operated early in the course of disease have better results. Decompression and instrumented fusion has better results than decompression alone.

305

P124: Should We Operate Asymtomatic Cervical Canal Stenosis? -Its Incidence in Operated Lumbar Canal Stenosis: A Retrospective Study

Hriday Acharya ¹ , Priyank Patel ¹ , and Abhay Nene ¹

¹ Lilavati Hospital and Research Center, Mumbai, India

Introduction: Patients with tandem stenosis generally present with overlapping symptoms of both cervical and lumbar cord compression which generally includes claudication, instability or slowing while walking and hyperreflexia. However, there is a large subset of patients who have a symptomatic compression at one region only lumbar more commonly than cervical, but on MRI screening of the whole spine, compression can be found at other regions as well which can get symptomic over time. Here in this study we aim at finding the percentage of patients operated for symptomatic lumbar canal stenosis who have asymptotic cervical canal stenosis (CCS) at time of operation and the cause of stenosis in each cases. Material and Methods: This is a retrospective study of patients operated for lumbar canal stenosis from January 2016- December 2019 at multiple hospitals by a single team of surgeons and reviewing their whole spine MRI films and clinical findings at time of operation from database. Canal stenosis in these patients will be looked for and graded as:- grade 0, no lesion; grade 1, any lesion compressing only the thecal sac; grade 2, any lesion in contact with the cord, without compression; grade 3, any lesion compressing the cord without signal change; and grade 4, any lesion compressing the cord with a signal change. Any observer bias will be eliminated by reviewing atleast 30 films by two teams and result matching in terms of grades of canal stenosis. Results: Of the 100 patients studied over 2 years, 83 patients fit into our inclusion criteria. Of them 49 patients had asymptomatic CCS, which comprised 59% of the study group. 29% of them had grade 1 CCS and 47% of them had single level stenosis. Of the 83 patients, 7 patients had single level grade 1 stenosis which we defined as non significant stenosis. The other, 49% comprised of significant CCS group. Conclusion: The incidence of asymptomatic cervical canal stenosis has been varied in various studies. In each of which the incidence remains high above 50%. This indicates a common trend of compression in world population which is not demographic nor due to bias. With such high incidence asymptomatic cervical canal stenosis shouldn’t be operated.

312

P125: Adjusted K-Line Outperforms Modified K-Line in Predicting Unsatisfied Clinical Outcomes After Laminoplasty

Guoyan Liang ¹ and Yunbing Chang ¹

¹ Guangdong Provincial People's Hospital, Guangzhou, China

Introduction: The Modified K-line was developed as a predicting tool for clinical outcomes after cervical laminoplasty. However, the Modified K-line is measured on the MR image with a prone position. The cervical alignments in prone positions are different from those in upright neutral positions, which led to less precision in assessing the residual spinal cord compression using the Modified K-line. We developed the Adjusted K-line by combining the upright neutral lateral X-ray and MR image in order to simulate the “actual location” of K-line when the patients are standing up straight. In this study, we compared the accuracy of surgical outcome prediction between Adjusted K-line and Modified K-line. Material and Methods: We retrospectively studied the prospectively collected data from 110 consecutive patients who underwent expensive open-door laminoplasty for treatment of degenerative cervical myelopathy and have been followed up for at least 1 year. Preoperative MRI and X-rays were collected for measurements of Adjusted K-line and Modified K-line. The adjusted C2 and C7 spinal cord midpoints were calculated in the MR image by rotating the C2 and C7 vertebrae around the compression factor to the same angles as those in the upright neutral lateral X-ray. Then the Adjusted K-line was defined as the line connecting the adjusted C2 and C7 cord midpoints. The Modified K-line was drawn according to previously reported. The minimum interval between the anterior structure of the spinal canal and the two lines were measured as INTadj and INTmod, respectively. Clinical outcomes were evaluated according to the preoperative and 1-year-follow-up Japanese Orthopaedic Association scale (JOA), the Japanese Orthopaedic Association Cervical Myelopathy Evaluation Questionnaire (JOACMEQ), and the numerical rating scale (NRS) for neck pain and arm pain. Unsatisfied clinical outcome was defined as the JOA recovery rate did not reach Minimal Clinically Important Difference (53%). The areas under the ROC curve (AUC) of INTadj and INTmod on predicting unsatisfied clinical outcomes were compared. Results: The average JOA recovery rate was 55%. Average improvements of JOACMEQ scores for Cervical spine function, Upper extremity function, Lower extremity function, Bladder function, and the Quality of life were 12.5, 17.9, 19.8, 9.8, 15.2, respectively. The Adjusted K-line showed good inter-observer reliability (α = .95) and intra-observer reliability (α = .92). The AUC of INTadj (AUC = .73) is larger than that of INTmod (AUC = .64) in predicting unsatisfied outcomes. The sensitivity of the Adjusted K-line was .83 and the specificity was .71 as the cut off value of INTadj being set at 2 mm. Conclusion: Adjusted k-line is more accurate than Modified K-line in predicting unsatisfied outcomes after laminoplasty for degenerative cervical myelopathy. The parameter INTadj less than 2 mm is a risk factor for unsatisfied clinical outcomes.

315

P126: Impact of Smoking Status on Surgical Outcomes After Cervical Laminoplasty

Guoyan Liang ¹ and Yunbing Chang ¹

¹ Guangdong Provincial People's Hospital, Guangzhou, China

Introduction: Cigarette smoking history has been considered to be a risk factor of poor clinical outcome after anterior cervical fusion surgery. However, whether smoking status affects the clinical outcomes after cervical laminoplasty is still unknown. The present study aimed to compare the clinical outcomes of active smokers and passive smokers to those of non-smokers following laminoplasty. Material and Methods: The authors prospectively studied a cohort of 188 consecutive patients who had undergone expansive open-door laminoplasty due to multilevel Cervical Spondylotic Myelopathy or Ossification of the Posterior Longitudinal Ligament. All patients were grouped into the Active-Smoking group (AS, those who had consumed cigarettes at least 3 months before surgery), the Passive-Smoking group (PS, those who had experienced daily exposure to the environmental tobacco smoke), and the Non-Smoking group (NS, those who did not smoke at all or within 3 months before surgery). Clinical outcomes were evaluated according to the preoperative and 1-year-follow-up Japanese Orthopaedic Association scale (JOA), the Japanese Orthopaedic Association Cervical Myelopathy Evaluation Questionnaire (JOACMEQ), and the numerical rating scale (NRS) for neck pain and arm pain. Results: All 188 patients completed at least 1 year of follow-up. There were 71 patients in the AS group, 27 patients in the PS group, and 90 patients in the NS group. The distributions of gender were different significantly among the three groups (Ratio of female: AS 0/71, PS 21/27, NS 38/90). Other baseline data, including age, BMI, symptom duration, comorbidity, preoperative JOA score, C2-7 Cobb angle, K-line status, and MRI T2 high intensity, were comparable within three groups. At 1-year-follow-up, the average recovery rate of JOA (AS 43%/PS 62%/NS 55%), as well as improvements of NRS for neck and arm pain, did not differ significantly. The improvements of each domain of JOACMEQ, including Cervical spine function, Upper extremity function, Lower extremity function, Bladder function, and the Quality of life, were similar among the three groups. When using 53% as the MCID of JOA recovery rate, active smokers (RR = .87, 95% CI = .62-1.21) and passive smokers (RR = .97, 95%CI = .65-1.44) had similar likelihoods of reaching MCID compared with non-smokers. No severe complications occurred in each group after surgery. Conclusion: During at least 1-year follow-up after expensive open-door laminoplasty, active smokers, passive smokers, and non-smokers had similar improvements in clinical outcomes. Smoking status was not found to be an independent predictor of clinical outcomes after laminoplasty. Our results suggested that laminoplasty is suitable for smokers with multilevel cervical diseases.

351

P127: Cervical Spondylotic Myelopathy: Comparative Study Between ACDF by Standalone PEEK Cage Versus Tricortical Bonegraft With Plate Fixation

Anowarul Islam ¹

¹ Bangabandhu Sheikh Mujib Medical University, Orthopaedics, Dhaka, Bangladesh

Introduction: ACDF is the commonest spine surgery performed for cervical disc prolapse. The purpose of this surgery is to decompress the spinal cord and nerve roots, as well as to achieve inter-vertebral stabilization. Multiple techniques and modalities of fixation like standalone PEEK cage, bone graft with plate fixation are used in ACDF, each with its merits and demerits. Material and Methods: 60 consecutive patients underwent Surgery in Bangabandhu Sheikh Mujib Medical University and other private hospitals in Dhaka city from July 2010 to June 2020. The VAS score was used to evaluate pain status. Pre- and post-operative Nurick scale was used to assess the myelopathy, Odom's criteria for the functional outcome and Bridwell interbody fusion criteria. Results: Among 60 patients 35 (58.3%) were males and 25 (41.7%) were females. The significant post-operative improvement was recorded after 12 months by VAS and Nurick scale. According to Odom criteria, we graded 27 patients (90%) excellent-good in the stand alone PEEK cage group in comparison to 25 patients (83.3%) in the tricortical bone graft with plate fixation group. The relation was not statistically significant between the two group as P < .30. There was no difference in improvement of VAS scores between two groups. Conclusion: ACDF is the ideal technique in the treatment of cervical spondylitic myelopathy with excellent functional outcome, good fusion which could be achieved by either PEEK cage or tricortical bone graft with some minor variation in complication and fusion.

392

P128: Comparison of Post-Operative Complications Between Different Types Surgical Approaches for Cervical Spondylotic Myelopathy

William Nguyen ¹ , Ki-Eun Chang ² , Blake Formanek ¹ , pouriya Ghayoumi ¹ , Zorica Buser ¹ , and Jeffrey C. Wang ¹

¹ Keck School of Medicine, University of Southern California, Department of Orthopaedic Surgery, Los Angeles, USA

² Keck School of Medicine, University of Southern California, Department of Neurological Surgery, Los Angeles, USA

Introduction: Cervical spondylotic myelopathy (CSM) is a major contributor to disability and reduced quality of life worldwide. The purpose of this study was to compare the incidence of complications and reoperation rates between the most common surgical treatments for CSM: anterior cervical discectomy and fusion (ACDF), anterior cervical corpectomy and fusion (ACCF), and posterior laminectomy and fusion (Lamifusion). Material and Methods: Humana insurance database was queried using the PearlDiver patient record database for CSM diagnoses between 2007 and 2016. The initial population was divided based on the surgical treatment and matched for age, gender, and Charlson Comorbidity index. Specific post-operative complications or revisions were analyzed at individual time points, up to a maximum of one year. Pearson X² analysis with Yate’s continuity correction was used. Results: 1094 patients from each of the treatment groups were matched for age, gender, and Charlson Comorbidity Index. LamiFusion had significantly higher rates of wound infection/disruption than ACDF or ACCF (5.03%, 2.19%, 2.29%; P = .0008, .002, respectively) as well as iatrogenic deformity (4.75%, 2.19%, 2.10%; P = .0036, .0013). Lamifusion also had a significantly higher rate of shock and same-day transfusion than ACDF (4.75%, 2.01%, P = .0005), circulatory complications (2.01%, <1%, P = .0183), and C5 palsy (4.84%, 1.74%, P = <.0001). Compared to ACDF, Lamifusion had higher rates of pseudarthrosis (3.29%, 2.01%, P = .0468), and revision surgery (8.23% 5.85%, P = .0395). Lamifusion had significantly lower rates of dysphagia than either ACDF (3.93% vs 6.58%, P = .0089) or ACCF (3.93% vs 8.59%, P < .0001). When comparing ACCF to ACDF, ACCF had significantly higher rates of circulatory complications (2.38%, <1%, P = .0053), shock/same-day transfusion (3.2%, 2.0%, P = .59), C5 palsy (3.47%, 1.74%, P = .0108), and revision surgery (9.51%, 5.85%, P = .0086). Conclusion: The data shows that posterior laminectomy and fusion has the highest overall rate of complications including wound complications, C5 palsy, mechanical failure and revision rate compared to ACDF or ACCF. As expected, rate of recurrent laryngeal nerve palsy and dysphagia was lower in the posterior approach. Furthermore, when comparing the anterior approaches, ACDF was associated with lower rate of complication and revision. ACCF had the highest overall rate of revision surgery.

399

P129: Post-Operative Complications and Readmission Rates Following Management of Cervical Degenerative Disease: A Retrospective Propensity Matched Study Between Anterior vs Posterior Approaches

Mohamed Mesregah ¹ , Joshua Bakhsheshian ² , Blake Formanek ¹ , Elliot Min ² , John Liu ² , Zorica Buser ¹ , and Jeffrey C. Wang ¹

¹ Keck School of Medicine, University of Southern California, Department of Orthopaedic Surgery, Los Angeles, USA

² Keck School of Medicine, University of Southern California, Department of Neurological Surgery, Los Angeles, USA

Introduction: Cervical degenerative disease is a common cause of acquired disability, yet there is still no consensus regarding the optimal surgical approach. The comparative outcomes of anterior as opposed to a posterior approach to cervical degenerative disease remain controversial. No previous study compared a matched cohorts of patients who had anterior or posterior approaches. This study aimed to compare the postoperative complications and readmission rates associated with either 1) anterior cervical discectomy and fusion (ACDF), 2) posterior cervical laminoplasty, and 3) posterior cervical laminectomy with fusion (lami+fusion), in a propensity score-matched patients. Material and Methods: A retrospective 1:1 propensity score-matched analysis of a national longitudinal database (Humana subset of the PearlDiver database) between 2007 to 2016 was conducted. Using relevant International Classification of Diseases (ICD-9 and ICD-10) and Current Procedural Terminology (CPT) codes, adult patients with degenerative cervical disease, who had either undergone ACDF, laminoplasty only, or lami+fusion at two or three spinal levels were identified. Patients with trauma, infections, tumors, or combined approaches were excluded. After propensity score matching, postoperative medical and surgical complications were analyzed with Chi-square test between the three groups. This was followed by pairwise comparisons between groups with Bonferroni adjustment of the level of significance (P > .017) for all groups. The 30-day readmission rates were also analyzed. Results: We identified 14,524 patients who had undergone either ACDF (n = 11,790), lami+fusion (n = 2,257), or laminoplasty (n = 477). Cohorts were balanced with propensity score matching resulting in 464 patients in each group. The incidence of dysphagia was highest following ACDF (12.7%), which was similar to lami+fusion (9.5%) but greater than laminoplasty, (<2.4%), P < .001. The incidence of new-onset cervicalgia was higher in ACDF (45.5%, P = .005) and in lami+fusion (45.7%, P = .004) compared to laminoplasty (36.2%). The incidence of limb paralysis was higher in lami+fusion (8.8%) compared to ACDF (3.7%), P = .002. The one-year revision rate was higher in lami+fusion (7.1%) compared to laminoplasty (<2.4%), P < .001, and in ACDF (5.2%) compared to laminoplasty, P < .001. The incidence of respiratory failure at 1 month was significantly higher in laminectomy with fusion (9.3%) than laminoplasty (3%), P < .001. However, there was no difference in the incidence of intraoperative spinal cord injury, nerve root injury, dural tear, postoperative dysphonia and kyphosis between the three groups. The 30-day readmission rates were 19.4% in the lami+fusion group, which was higher than the 12.1% in the laminoplasty, P = .003, and 9.3% observed in the ACDF group (P < .001). Conclusion: Of the three groups, laminoplasty was associated with the lowest incidence of postoperative new-onset cervicalgia and revisions. Laminectomy and fusion was associated with higher postoperative neurologic deficits, revision and readmission rates. Interestingly, rates of dysphagia were similar amongst laminectomy and fusion with ACDF. These findings are limited by the retrospective longitudinal database.

439

P130: Anterior Cervical Discectomy Fusion (ACDF) with Self-Locked Cages for 4-Level Cervical Disc Herniation

YuTong Gu ¹ , Wu Che ¹ , Liang Zhang ¹ , and Yichao Wang ¹

¹ Zhongshan Hospital Fudan University, Shanghai, China

Introduction: Anterior cervical plate has protruding profile, which usually leads to the sensation of swallowing foreign body, and self-locked cage has no profile. The purpose of study is to evaluate the feasibility, efficacy and safety of ACDF with self-locked cages for the treatment of 4-level cervical disc herniation. Materials and Methods: Sixteen cases of C3/4, 4/5, 5/6, 6/7 disc herniation with myelopathy or radiculopathy were included in this study. ACDF using self-locked cages (LDR) filled with allograft was performed for C3-7 under general anesthesia. Arm pain was preoperatively and postoperatively evaluated using VAS and the severity of the neurologic deficit was assessed using the ASIA impairment scale. The clinical outcomes were evaluated with Oswestry Disability Index (ODI) and cervical range of motion (CROM) in 6 directions was measured at the 2-year follow-up. The fusion status was assessed according to the Bridwell’s posterior fusion grades. Results: Sixteen patients, seven women and nine men with a mean age of 61.2 ± 10.6 years, were included in the present study. The duration of operation was 185.0 ± 30.5 min The mean length of the incision was 2.2 ± .4 cm. There was a mean blood loss of 35 (15–180) mL. The stay at hospital was 4 (3-5) day. The average follow-up duration was 26 (24-36) months. There were no perioperative complications such as swallowing foreign body sensation. The VAS score and ODI showed excellent outcomes. CROM in 6 directions was close to normal, which had not affected daily life. Fusion grades based on the Bridwell grading system at 2-year follow-up were grade I in 57 segments (89.1%, 57/64), grade II in 7 segments (10.9%, 7/64). Conclusion: ACDF with self-locked cages is a good choice of minimally invasive surgery for 4-level cervical disc herniation, which can get good clinical outcomes, rigid fixation, solid fusion and no swallowing foreign body sensation.

Keywords

cervical disc herniation, cervical spondylotic myelopathy, cervical spondylotic radiculopathy, anterior cervical discectomy, anterior cervical interbody fusion

487

P131: Calcification of Ligamentum Flafum

Rihab Benfredj ¹ , Ilyes Krifa ¹ , Abdelhafidh Slimane ¹ , and Khansa Abderrahmane ¹

¹ Institute Of Neurology, Neurosurgery, Tunis, Tunisia

Introduction: Ossification and calcification of ligamentum flavum (OCLF) are rare causes of thoracic or cervical myelopathy. This condition concerns especially eastern Asian citizens. The exact pathophysiology of OCLF has not yet been elucidated. Material and Methods: We retrospectively reviewed the medical records of four patients with ossification or calcification of ligamentum flavum causing myelopathy treated in our department of neurosurgery (Department of Neurosurgery of the National Institute of Neurology) during the past 5 years and tried to report the clinical, radiological features and the post-operative outcome. Results: The series is about three male patients and one female (25%). Age ranged between 58 and 73 years with a mean age at presentation of 65.5 years. Progressive aggravating spinal cord compression symptoms were observed in all cases. The compression interested the cervical spine (1 case), lumbar spine (1 case), thoracic spine (1 case) and extending from the cervical to the lumbar spine (1 case). MRI was the imaging modality in all cases, while one patient was explored by CT-scan. Surgical approach consisted on a selective laminectomy and ligamentum flavum resection in the area of compression. One patient was not operated because of multiple lumbosacral bedsores. The histological results showed 2 cases of ossification and one case of calcification of ligamentum flavum. The severity of the preoperative symptoms and diagnostic delay were the most important prognostic factors. Conclusion: Early diagnosis and surgical decompression could improve the functional prognosis of patients harboring calcification or ossification of ligamentum flavum. The resemblance between these two affections may suggest a similar pathophysiology.

528

P132: Minimally Invasive Posterior Cervical Foraminotomy Versus Open Posterior Cervical Foraminotomy, Anterior Cervical Discectomy and Fusion, and Cervical Total Disc Arthroplasty: Systematic Review and Meta-Analysis

Andrew Platt ¹ , Richard Fessler ² , Vincent C. Traynelis ² , and John O'Toole ²

¹ University of Chicago, Chicago, USA

² Rush University Medical Center, Chicago, USA

Introduction: Patients with lateral cervical disc and foraminal pathology in the cervical spine can be treated with anterior and posterior approaches including anterior cervical discectomy and fusion (ACDF), cervical total disc arthroplasty (TDA), minimally invasive posterior cervical foraminotomy (MIS-PCF), and open posterior cervical foraminotomy (O-PCF). Although MIS-PCF may have some advantages over the other approaches, few comparative studies and meta-analyses have been done to assess superiority. Material and Methods: A systematic review of literature was conducted based on the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) statement. Meta-analysis was performed if there were three or more studies that evaluated the same variable. Results: Twelve studies were included in quantitative synthesis including five studies that directly compare MIS-PCF to O-PCF, six studies that directly compare MIS-PCF to ACDF, and two studies that directly compare MIS-PCF to TDA. In comparing patients undergoing MIS-PCF and O-PCF, mean operative time ranged from 60.5 minutes to 171 minutes in the open group and 77.65 minutes to 115 minutes in the MIS group. Average postoperative length of stay ranged from 58.6 hours to 304.8 hours in the open group and 20 hours to 273.6 hours in the MIS group. There were no significant differences in complications or reoperations between open and MIS groups. In comparing patients undergoing ACDF and MIS-PCF there were no significant differences in mean operative time or postoperative length of stay. The total complication rates were 1.96% in the ACDF group and 1.59% in the MIS-PCF group. A random-effects model meta-analysis was carried out which showed a higher complication rate after ACDF, however, it did not reach statistical significance (OR 1.35; 95% CI .26, 7.00; P = .72, I2 = 52%). The reoperation rate ranged between 0 and 5.7% and 0 and 14.3% for ACDF and MIS-PCF groups respectively. A random-effects model meta-analysis was carried out which showed a statistically significant decrease in reoperations following ACDF (OR .56; 95% CI .32, .96; P = .03, I2 = 0). In comparing patients undergoing TDA and MIS-PCF, operative time ranged from 90.3 to 106.7 minutes in the TDA group compared to 77.4 to 93.9 minutes in the MIS-PCF group. Mean postoperative length of stay ranged from 103.2 to 165.6 hours in the TDA group and 93.6 to 98.4 hours in the MIS-PCF group. The complication rate ranged from 23.5 to 28.6% in the TDA group and 0 to 14.3% in the MIS-PCF group. The overall reoperation rates were 2.6% in the TDA group and 10.2% in the MIS-PCF group. Conclusion: Although there is a trend of decreased hospital length of stay following MIS-PCF, there is not enough data to suggest a statistically significant difference between MIS-PCF and O-PCF in complication and reoperation rate. There is no clear superiority between MIS-PCF and ACDF/TDA in terms of operative time, postoperative length of stay, or rate of complications. There is a decreased rate of reoperation following ACDF as compared to MIS-PCF, however, reoperation rates for both procedures are low and the comparison is limited by short follow-up times for ACDF.

590

P133: Myelopathy Predicts 5-Year Survival in the Elderly Above 80, Following Posterior Cervical Spine Surgery. A Cohort Study of 60 Patients

Adeel Ikram ¹ , Christopher Busby ¹ , Rajendra Bommireddy ¹ , and Zdenek Klezl ^1,2

¹ Royal Derby Hospital, Trauma & Orthopaedics, Derby, United Kingdom

² Department of Surgery, 1st Medical School Charles' University Prague, Praha 2, Czech Republic

Introduction: Elderly patients present with unique challenges. Many have multiple comorbidities, which have been proven in medical and surgical specialties to carry an increased risk of morbidity and mortality. However, there is little data in literature on the survival rates of the elderly above the age of 80, undergoing cervical spinal surgery. Existing studies have demonstrated increasing morbidity and unplanned readmission following elective anterior cervical surgery. The aim of this study is to ascertain if myelopathy plays a significant role in the survival of the elderly above 80, and if the presence of medical comorbidities in myelopathic patients contributes to their survival at 5 years. Materials and Methods: This study is an analysis of prospectively collected data, of all patients greater than the age of 80 undergoing elective posterior cervical surgery for degenerative disease at our institution from 2006 to 2018. Inclusion criteria were elective cervical degenerative disease, age ≥ 80, posterior cervical spinal surgery. Indications for surgery included canal stenosis, spondylolisthesis, radiculopathy, and myelopathy. Exclusion criteria included trauma, metastatic disease, anterior cervical spinal surgery or combined anterior and posterior procedures. The Charlson Comorbidity Index (CCI) a validated measure of predicting 10-year survival in medical patients was calculated. Mortality and comorbidity data were collected. Statistical analysis was performed using one-way analysis of variance (ANOVA), Paired samples T test and Pearsons Chi-squared test where appropriate. Receiver operative characteristic and Cox regression was performed for survival analysis. Results: Our study includes 60 patients. There was no statistically significant difference between gender, pre and post-Nurick score, length of stay and presence of medical comorbidities, between myelopathic and non-myelopathic patients. There was a statistically significant difference in age and mean days survived following surgery between myelopathic and non-myelopathic patients (P = .005 and P = .001 respectively). Receiver operative characteristic analysis demonstrates myelopathy can predict survival in patients with an accuracy of 71.4% at 5 years. Regression analysis demonstrates a decreasing survival with presence of myelopathy HR 5.452, 95%CI (2.309, 12.856) adjusted for age, sex and presence of medical comorbidities. Myelopathic patients have a predicted 5-year survival of 20%, and non-myelopathic patients have a predicted 5-year survival of 75% in this age group. There was no statistical significance between survival and the presence of medical comorbidities (P = .450) in myelopathic patients. Conclusion: The presence of myelopathy is a significant factor in the outcome of the elderly above 80 years of age and its presence can be used to predict survival at 5 years. The presence of medical comorbidities in myelopathic patients above the age of 80 does not play a role in survival outcome and neither does age. We advocate early surgery in patients without myelopathy as their survival is greater and we also advocate informed decision making in patients with myelopathy.

595

P134: Four-Level Anterior Cervical Discectomy and Fusion for Cervical Spondylotic Myelopathy: Our Institutional Experience

Kais Maamri ¹ , Ines Cherif ¹ , Amine Trifa ¹ , Mahmoud Ben Messaoud ¹ , Nessrine Nessib ¹ , Maher Hadhri ¹ , Mohamed Badri ² , and Mehdi Darmoul ¹

¹ Fattouma Bourguiba University Hospital, Neurosurgery, Monastir, Tunisia

² Trauma and Major burns center Ben Arous, Neurosurgery, Ben Arous, Tunisia

Background: Cervical spondylotic myelopathy (CSM) is a common age-related degenerative disease that can lead to motor and sensory dysfunction. The optimal treatment for multi-level CSM (defined as ≥3 levels) remains controversial. Eventhough Anterior cervical discectomy and fusion (ACDF) demonstrates reliable improvement in neurologic symptoms, in some cases posterior decompression is needed. There is a paucity of data on outcomes following 4-level ACDFs. The purpose of this study was to evaluate clinical outcomes for patients undergoing 4-level ACDF. Methods: 8 patients with cervical spondylotic myelopathy underwent four-level ACDF over a period of 3 years and were retrospectively reviewed and followed-up. Patients’ demographics, symptoms, neurologic findings, and radiographic findings at admission were recorded. Clinical outcomes, including fusion rates and neurologic outcomes were determined. Results: Retrospective review of our institutional database revealed 8 patients who underwent 4-level ACDF. Average age was 56.2 years (range 39-68 years); 6 (75%) were male. 75% of patients presented with neurologic deficits. The mean follow-up after surgery was about 13 months. All patients had good recovery of muscle strength and resolution of limb sensory disturbance. None worsened after surgery. No complications were recorded in our series. Till now we haven’t record any adjacent-level disease or pseudarthrosis. Conclusions: 4 levels ACDF is safe and effective for multilevel cervical spondylotic myelopathy and achieves satisfactory mid-term clinical and radiological outcomes with minimal intra-operative and post-operative complications.

Keywords

Cervical spondylotic myelopathy, anterior cervical discectomy and fusion, four Levels Cervical Disc

616

P135: C2/3 as the Proximal Instrumented Level or Crossing the Thoracolumbar Junction; Which has the Greatest Effect on the Outcomes and Complications After Long-Segment Posterior Cervical Fusion Surgery? A Retrospective Study from a Single Tertiary Spine Institution

Jamie Wilson ¹ , Thorsten Jentzsch ² , Anna Rienmuller ² , Jetan Badhiwala ² , and Eric Massicotte ²

¹ University of Nebraska Medical Center, Neurosurgery, Omaha, USA

² University of Toronto spine program, Toronto, Canada

Introduction: Long-segment posterior decompression and fusion surgery in the cervical spine is an effective procedure to treat a range conditions including cervical myelopathy, deformity, multi-level radiculopathy and traumatic injury. The effect of the choice of the proximal and distal instrumented level on the quality of life outcomes and perioperative complications has not been fully defined in the existing literature. The objective of this study was to investigate the effect of the site of the proximal (C2 or C3) or distal (Cervical or Thoracic) instrumented level (PIL, DIL) on the outcomes and complications after posterior cervical fusion surgery. Material and Methods: Operative database records from a single tertiary spine institution were interrogated for adult patients undergoing posterior cervical fusion surgery with a PIL of C2 or C3. Prospectively-collected outcome measures, pain scores, demographic data (including the DIL; cervical or thoracic) and perioperative complication rates were recorded, together with follow up data. Univariate analysis was performed to assess the effect of age, levels fused, PIL and DIL on complication rate, Oswestry Disability Index Scores (ODI), numerical rating scale (NRS) pain scores and risk of revision surgery. A multivariable regression model was constructed to investigate the combined effects of age, PIL, DIL, gender and number of levels on all outcomes. Results: 131 patients were included, 49 (37%) were female, with a mean age of 62 [95%CI 60-64]. Indication for surgery was myelopathy in 95% of cases, with an average of 4 levels fused (range 3-8). Mean follow up for all patients was 47 [41-53] months. Blood loss, duration of surgery, risk of complications or revision were equivalent between PIL groups (P = .27, P = .16, P = .32, P = .32). Risk of complication was higher in the thoracic DIL group (OR 2.86[1.04-7.87]; P = .042), but revision rate was no different (P = .61). Age was not associated with risk of complication or revision, but risk of complication increased by 1.7[1-2.7] per level fused (P = .032). PIL or DIL groups showed no difference in ODI scores or neck/arm NRS scores. Multivariable analysis showed PIL remained not associated with ODI or NRS scores. However, increasing age was significantly associated with improved neck NRS score (−0.062[−0.11-0.017]; P = .007) and thoracic DIL was significantly associated with higher arm NRS scores (2.3[0.36-4.25]; P = .021). Conclusion: The choice of PIL (C2 or C3) does not appear to affect the risk of complications, revision rate or quality of life outcomes after long-segment posterior cervical fusion surgery. Multivariable regression suggests age and a thoracic DIL has significant effects on post-operative NRS scores, however these results require further prospective investigation to be fully validated.

777

P136: Neurological Recovery and Radiological Evaluation After Surgical Decompression in Patients with Cervical Myelopathy

Mohamed Badri ¹ , Kais Maamri ² , Mourad Masmoudi ¹ , Ghassen Gader ¹ , Mouna Rkhami ¹ , Kamel Bahri ¹ , and Ihsen Zammel ¹

¹ El Manar-Tunis university, Faculty of Medicine of Tunis, Department of Neurosurgery, Burns and Trauma Center, Ben Arous, Tunisia., Ben Arous, Tunisia

² Fattouma Bourguiba University Hospital, Department of Neurosurgery, Monastir, Tunisia, Monastir, Tunisia

Introduction: Cervical myelopathy is a clinical and radiological syndrome that displays chronic spinal distress due to cervical ductal narrowness. The long-term functional prognosis and outcome of treated patients depend mainly on surgical procedures. This study aims to evaluate the clinical and radiological aspects of this pathology and to appraise the pattern of neurological recovery as well as the postoperative radiological findings. Materials and Methods: We analyzed 50 cases of patients suffering from cervical myelopathy who underwent surgery between March 2012 and January 2015 in the neurosurgical department of Burn and Trauma Center of Ben Arous. Patients were assessed clinically using the JOA (Japanese Orthopaedic Association) and Nurick scores and radiologically, before and after surgery. Results: The average age was 58.7 years with a male predominance (74%). Cervicalgia (94%), walking disorders (92%) and cervico-brachial neuralgia (80%) were the most predominant clinical symptoms. The average duration of symptoms was 18.8 months. All patients underwent cervical decompression surgery through anterior (46%), posterior (52%) and combined (2%) approaches. The Nurick mean score passed from 3.5 preoperatively to 2.25 postoperatively and the JOA mean score increased from 11.4 preoperatively to 14.2, 2 years after surgery. The average of the recovery rate reached its highest (44.7%) 3 months postoperatively and stabilized thereafter. Severity of preoperative neurological impairment (P = .027), the degree of narrow cervical canal (P = .031), and intramedullary hyper-signal on magnetic resonance imaging (P = .042) were the main factors that had a significant impact on patients’ neurological improvement. Conclusion: The kinetics of neurological recovery appears to be rapid within 3 months following the surgical decompression, after which it became stable regardless of the surgical technique used.

783

P137: Is Predominant Neck Pain a Risk Factor for Worse Postoperative Outcomes Following Anterior Cervical Discectomy and Fusion for Cervical Radiculopathy?

Graham Goh ¹ and Reuben Soh ¹

¹ Singapore General Hospital, Singapore, Singapore

Introduction: Surgeons often base decisions on the traditional belief that the predominance of radicular upper extremity symptoms is a stronger indication for cervical spine surgery than axial pain. However, there is a paucity of literature supporting this notion. This study aimed to determine how different combinations of preoperative neck pain (NP) and arm pain (AP) influence functional outcomes, patient satisfaction and return to work in patients undergoing Anterior Cervical Discectomy and Fusion (ACDF) for Degenerative Cervical Radiculopathy (DCR). Materials and Methods: Patients undergoing a primary, one- to two-level ACDF for DCR were retrospectively reviewed and stratified into three cohorts based on predominant pain location: AP predominant ([APP]; AP > NP), NP predominant ([NPP]; NP > AP) and equal pain predominance ([EPP]; NP = AP). Demographic and perioperative characteristics were recorded. Differences in PROs, including Neck Disability Index (NDI), 36-Item Short-Form Physical Component Score (SF-36 PCS), Mental Component Score (SF-36 MCS), AAOS Neurogenic Symptom Score (AAOS-NSS), Visual Analogue Scale (VAS) for NP and AP, at each postoperative time point were compared using general linear models. Achievement of minimum clinically important difference (MCID), patient satisfaction assessed using the North American Spine Society (NASS) questionnaire, and return to work were compared using Chi-squared analysis. Results: In total, 303 patients were included: 83 APP, 118 NPP and 102 EPP. APP patients were significantly older; however, there were no other preoperative differences in sex, BMI, comorbidities, smoking status, diagnoses (radiculopathy or myeloradiculopathy) or number of levels. APP patients had the best baseline NDI (P < .001) whereas NPP patients had the least neurogenic symptoms (P < .001). After adjusting for baseline differences, APP patients had significantly higher SF-36 PCS at 6 months and 2 years (Table 3). They also showed a trend towards better 6-month NDI (P = .077) and 2-year SF-36 MCS (P = .059). However, all three cohorts had similar rates of MCID achievement for NDI and SF-36 PCS. At 2 years, 83%, 76% and 85% in the APP, NPP and EPP groups were satisfied with treatment, respectively (P = .253), while 95%, 95% and 98% returned to work (P = .981). Conclusion: Although NPP patients had poorer function and quality of life, a similar proportion experienced a clinically meaningful improvement. High rates of satisfaction and return to work were also achieved regardless of predominant pain location.

815

P138: Cervical Facet Joint Arthritis-Synovitis in Patients With Neck Pain: MRI Findings and Their Clinical Presentation

Alvaro Silva ¹ , Pablo Carreño ² , Ratko Yurac ¹ , Juan José Zamorano ¹ , Guillermo Izquierdo ¹ , Matías Delgado ¹ , Álvaro Soteres ³ , and Bartolomé Marré ¹

¹ Clínica Alemana Universidad del Desarrollo, orthopaedics, santiago, Chile

² Clínica Alemana Universidad del Desarrollo, Rehabilitation, santiago, Chile

³ Mutual de seguridad de la CCHC, orthopaedics, santiago, Chile

Introduction: Identifying the precise pain generator can be challenging in the work up of patients presenting with neck pain, due to the high prevalence of degenerative disc, unciform and facet joint changes in the population. Magnetic Resonance Imaging (MRI) can show us signs of active inflammation, allowing us to get a more accurate diagnosis/pain source. Arthritis-synovitis of the cervical facet joint is an MRI finding, particularly evident in fat saturation sequences (STIR), characterized by high intensity signal of pericapsular tissues, bone, and the presence of joint effusion. There is scarce literature available about this entity, particularly regarding its prevalence, clinical presentation, and clinical-radiological correlation. The main purpose of this study is to evaluate the correlation between MRI (STIR) findings of facet joint arthritis-synovitis and symptoms among patients presenting with neck pain. As a secondary objective, we want to describe the pain patterns associated with these MRI findings. Material and Method: Retrospective descriptive study of a series of 56 patients consulting for mechanical neck pain at our center from 2014 to 2019, who presented MRI (STIR) findings of cervical facet arthritis-synovitis. Exclusion criteria: previous cervical surgery, cervical spine fractures, infections, and incomplete clinical records. We analyzed demographics, clinical characteristics, neck pain pattern, presence of neurological signs/symptoms, affected level and side with arthritis-synovitis in the MRI and its correlation with the pain laterality reported by the patient. Results: 64.29% were woman, average age 60 years (Std. 10.47). Regarding symptoms, 96.43% reported unilateral pain and 57.14% had chronic pain. We identified five neck pain patterns: Arnold neuralgia (16.1%), high neck pain (28.6%), mid neck pain (19.6%), lower neck pain (19.6%) and cervicobraquialgia (16.1%). 96.43% had no neurological signs/symptoms, while 92.86% had positive tests for cervical facet joint irritation. The C3-C4 segment had the highest frequency of MRI periarthritis 42.8% and 73% of the patients presented MRI facet joint findings between C1 and C4. Finally, regarding the correlation between symptoms and imaging findings, 92.86% of the patients reported neck pain on the same side of the MRI findings. Conclusions: Despite the retrospective nature of this study and the probable selection bias based on MRI findings, we observed a strong relationship between the presence of facet joint arthritis-synovitis and the laterality of mechanical neck pain without neurological signs/symptoms. Patients most frequently reported high neck pain and had a positive facet irritation test. This study is the basis for cervical facet periarthritis pain prevalence studies and a potential definition of a characteristic clinical-radiological picture.

851

P139: Quality Assessment of Systematic Reviews of the Surgical Treatment of Cervical Spine Degenerative Diseases: An Overview

Nelson Astur ^1,2 , Delio E. Martins ^1,3 , Michel Kanas ^1,4 , Rodrigo Goes ^1,2 , Aaron T. Creek ⁵ , Mario Lenza ⁶ , and Marcelo Wajchenberg ^1,4

¹ Hospital Israelita Albert Einstein, Orthopaedics - Spine Group, Sao Paulo, Brazil

² Santa Casa de Sao Paulo School of Medical Sciences, Department of Orthopaedics and Traumatology, Sao Paulo, Brazil

³ Universidade Anhembi-Morumbi, School of Medicine, Sao Paulo, Brazil

⁴ Universidade Federal de Sao Paulo, Department of Orthopaedics and Traumatology, Sao Paulo, Brazil

⁵ Norton Leatherman Spine Center, Louisville, KY, USA

⁶ Hospital Israelita Albert Einstein, Orthopaedics, Sao Paulo, Brazil

Introduction: There appears to be a substantial mismatch between the results of systematic reviews in spine surgery and daily practice outcomes. Reviews comparing surgical treatments for degenerative cervical diseases should provide the highest source of scientific evidence but quality of studies are frequently questioned. The aim of this study was to gather all systematic reviews for surgical treatment of degenerative cervical diseases and assess their quality, conclusions and outcomes. Material and Methods: A literature search for systematic reviews that employ at least a single surgical treatment method of degenerative cervical spine disease was conducted through available medical databases: Medline, Embase, Cochrane, and DARE. Two investigators independently assessed all titles and abstract for inclusion. Studies should have at least one surgical procedure as an intervention. Included studies were assessed for quality through the PRISMA and AMSTAR questionnaires. Quality of studies was rated accordingly to their final score as very poor (<30%), poor (30-50%), fair (50-70%), good (70-90%), and excellent (>90%). If an article reported a conclusion addressing its primary objective with supportive statistical evidence for it, they were deemed to have an evidence-based conclusion. Population was grouped according to the disease investigated (cervical disc herniation, myelopathy, spondylosis, degenerative disc disease and compared. Results: Overall, there were 65 systematic reviews included. According to AMSTAR and PRISMA, 1.5% to 6.2% of the studies were rated as excellent, while good studies counted for 21.5-47.7%. According to AMSTAR scores, most studies were of fair quality (46.2%), and 6.2% of very poor quality. Overall, mean PRISMA score was 70.2%, meaning studies of good quality. For both tools, performing a meta-analysis significantly increased studies scores and quality. According to disease studied, reviews of cervical spondylosis reached highest scores with all studies being of good or excellent quality. Authors stated conclusions for interventions compared in 70.7% of studies and only two of them were not supported by statistical evidence. When reviews were grouped according to the disease studied, the percentage of "good" or "excellent" studies considering PRISMA was higher for spondylosis studies, achieving all nine reviews for this disease (100%), followed by studies of myelopathy (51.8%) and DDD (50%). Conclusion: Systematic reviews of surgical treatment of cervical degenerative diseases present "good" to "excellent" quality in their majority and most of the reported conclusions are supported by statistical evidence. Including a meta-analysis significantly increases the quality of a systematic review. Therefore, authors suggest that readers should analyze cautiously strength of every review based on their methodology and included studies since two good quality papers comparing same interventions may present opposing recommendations.

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P140: Anterior Cervical Decompression and Fusion with Plating in Two-Level Cervical Degenerative Disease

Kyaw Linn Linn ¹

¹ Yangon Orthopaedic Hospital, Yangon, Myanmar

Introduction: Surgery decompression has been accepted as the predominant treatment of degenerative cervical disease with pain and neurological deficit. Anterior cervical decompression and fusion which solves both static and dynamic compression can bring better outcomes among various procedures, being the gold standard in single level disease. But for two-level disease, fusion status and cervical alignment are also of paramount importance besides pain and neurological recovery. According to studies, ACDF with plating can bring superior outcome and, fusion is better with auto graft than allograft and cage in several aspects. Therefore anterior cervical decompression fusion using auto graft and plating might bring better outcome in two-level diseases. But, to the authors’ knowledge, there are very few similar prospective study to address the efficacy of ACDF with plating with respect to fusion status and cervical alignment, outcomes in patients with two-level diseases. Purpose of this study is to evaluate to know fusion rate, cervical alignment changes, neurological recovery, neck pain and complications after this procedure and to determine their associations. Material and Methods: This study is hospital based descriptive clinical outcome study analyzing 28 two-level cervical degenerative disease patients who were treated with ACDF with plating. Clinical outcomes were measured by neck diability index, the Visual Analog Scale for neck and radicular pain and by mJOA score. Radiological outcomes were assessed for fusion status in dynamic X-rays, and for alignment by lordotic angles, T1 slope and SVA in lateral X-rays at Yangon Orthopaedic Hospital (Myanmar) from Sept 2018 to Aug 2020. Results: Total 26 patients were included with male sex predominance (M: F = 16: 10) and mean age of the patient was 48.32 ± 8.32 years (range 24 –70 year). C5-6-7level was most commonly affected (48%). Analysis were done on the basis of clinical and radiological criteria. VAS neck pain (4.52 ± 1.93 to .42 ± .72) and arm pain (6.23 ± .95 to .29 ± .52) as well as NDI and, mJOA score improved from preop to final follow-up. Sagittal alignment could be restored to lordosis curvature (14.77 ± 5.23 degree to 24.71 ± 2.37 degree). Fusion is complete within six months in most cases. This is ongoing study and will be finished in Nov 2020, and up to now, there was negative correlation and moderate association between neck pain and sagittal alignment (r = −.501)(P < .05) But there were no significant correlation between functional outcome and alignment. There was positive correlation and moderate association between overall lordotic angle and segmental lordotic angle (r = .595) (P < .001). Conclusion: Anterior cervical decompression and fusion with plating in two level degenerative cervical disc disease is an effective and acceptable procedure. It can maintain sagittal alignment and enhance fusion. Achievement of cervical lordosis and bony fusion remains major goal of surgery, even though sagittal alignment have no correlation with clinical outcomes. But there is correlation among neck pain, alignment and fusion. A larger study with longer follow-ups would be required to determine adjacent segment degeneration and long term functional outcome.

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P141: A New Interlocking Technique in Anterior Cervico-Thoracic Spinal Fixation with Dramatically Reducing the Pull-Out Strength of the Screws in Pediatric Spinal Instrumentation

Senol Jadik ¹

¹ Wara Hospital, Neurosurgery, Kuwait City, Kuwait

Introduction: The evolution of pediatric spinal instrumentation has progressed with adaptation of adult instrumentation techniques and tools, but nevertheless there is a lack in pediatric-specific spinal instrumentation. Complex spine disorders are still challenging and require additional techniques in fixation rather than screws only. We report our new interlocking technique in anterior spinal fixation with dramatically reducing the pull-out strength of the screws. Material and Methods: We report about the case of a 1.5 years old infant who underwent a complex spine surgery from C7 to T3. Patient demographics, operative data, and perioperative complications were recorded. At the same time, the authors surveyed the literature for spinal instrumentation techniques that have been utilized in the pediatric spine. Results: After corpectomy T1 and T2 and decompression of the spinal cord ACDF with the smallest cervical PEEK 5 × 12 mm cage and a special plate from orthopedic finger plating system and 6-8 mm long screws to fix the vertebral bodies. The anterior plate is fixed with another plate which is bended as a hook and placed with the posterior end behind T3 and with the anterior end to the previous plate in an interlocking manner. A small soft collar was been adjusted and no external Halo fixator was necessary. The construction was stable during the follow ups. Conclusion: Pediatric spine surgeons with an interest in complex spine disorders in children need a safe and strong technique for placing spinal instrumentation even in the smallest of children, with low complication rates and comfortable perioperative feasibility. The new interlocking technique of anterior spinal fixation reduces dramatically the pull-out strength of the screws, which is significant in weak bones of infants and adds a valuable postoperative comfort for the patient. For our knowledge, this is the first described technique in the literature to enhance the stability of an ACDF construction.

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P142: The Spectrum and Prevalence of MRI Pathologies of Patients Undergoing Surgery for Degenerative Cervical Myelopathy: Analysis of an Ongoing Prospective Study

Aria Nouri ¹ , Granit Molliqaj ¹ , and Enrico Tessitore ¹

¹ Geneva University Hospitals, Neurosurgery, Geneva, Switzerland

Introduction: Degenerative Cervical Myelopathy (DCM) is the most common cause of spinal cord impairment. Multiple studies have attempted to better delineate diagnostic and predictive factors. However, it is clear that such research will depend on the understanding of the heterogeneity of this population. Using an ongoing prospective study, we report a preliminary finding of a wide based set of MRI findings present preoperatively in patients undergoing surgical treatment for DCM. Material and Methods: Patients with clinical DCM are automatically enrolled into our institutional protocol which includes MR imaging. The study is IRB approved and consent for inclusion into the study are obtained from patients enrolled into this study from 2012 to 2019. MRIs were reviewed for the presence of types of pathologies the level of highest compression, the number of levels involved in compression or touching the spinal cord, T2 weighted signal changes (including the presence of vertical skip lesions), the maximum canal compromise and maximum spinal cord compression based on sagittal imaging. All measurements were conducted based on previously reported techniques. Results: 56 patients with DCM were included. The average number of compressed levels was 2.3. The most common level of maximum compression was C5-6 (36%), followed by C4-5 (30%). C5-6 and C4-5 were also most commonly implicated in cord compression presenting in 70% and 62.5% of patients, respectively. T2 signal hyperintensity was observed in 75% (n = 42) and vertical skip lesions (segmentation) was observed in 8.9% (n = 5) of patients. Specific pathologies present included: Multilevel degeneration (spondylosis) 75%, single disc herniation 21.4%, OPLL 14%, ligamentum flavum hypertrophy/bulging 39.3%, Spondylolisthesis 33.9%, Klippel-Feil Syndrome 3.57%, Modic changes 33.93%, Cord-Canal mismatch (congenital cervical stenosis) 14%, Hyperostosis of ALL (DISH, Diffuse Idiopathic Skeletal Hyperostosis) 10.7%. The average sagittal canal compromise at the most stenotic level was 48.3% (26.3-75%) and the average maximum spinal cord compression was 34.1% (7.1-68%). Conclusion: Patients with DCM present with a wide range of imaging findings and pathologies. It is worthy of note that many pathologies rarely reported amongst DCM patients are also commonly found in this population, including DISH and Modic changes. This study confirms that future studies assessing surgical outcomes should bear in mind that these varying features may have impacts on neurological outcome, surgical-decision making and quality of life assessments.

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P143: Provision and Perception of Physiotherapy in the Non-Operative Management of Degenerative Cervical Myelopathy: A Cross-Sectional Questionnaire of People Living with DCM

Max Butler ¹ , Oliver Mowforth ¹ , Abdul Badran ¹ , Michelle Starkey ² , Timothy Boerger ² , Iwan Sadler ² , Julia Tabrah ³ , Caroline Treanor ⁴ , Lucy Cameron ¹ , Sukhvinker Kalsi-Ryan ⁵ , Rodney Laing ¹ , Benjamin Davies ¹ , and Mark Kotter ¹

¹ University of Cambridge, Division of Neurosurgery, Department of Clinical Neurosciences, Cambridge, United Kingdom

² Myelopathy.org, Cambridge, United Kingdom

³ NHS Berkshire Healthcare, Integrated Pain and Spinal Service, Berkshire, United Kingdom

⁴ Beaumont Hospital, Neurosurgical Spinal Service, Dublin, Ireland

⁵ KITE Research Institute, Toronto, Canada

Introduction: Degenerative cervical myelopathy (DCM) is a common syndrome of acquired spinal cord impairment caused by canal stenosis secondary to arthritic changes of the spine. International guidelines consider physiotherapy an option for mild, stable DCM, however, few studies have been conducted on non-operative management. The objective was to determine current usage and perceptions of non-operative physiotherapy for DCM. Material and Methods: Persons with DCM were recruited to a web-based survey. Participants with complete responses that had not received surgery were included (n = 167). Variables included symptom duration, treatment history, current disability and demographic characteristics. Results: Half of the survey respondents had received physiotherapy (82/167, 49%). Demographic characteristics were equivalent between those who did and did not receive physiotherapy. There was no significant difference in disability between those who did and did not receive physiotherapy (Nurick 1.9 ± 1.4 vs 2.0 ± 1.4, p = .850; mJOA, P = .311). In total, 79.3% of individuals who received physiotherapy had moderate or severe DCM, compared to 70.6% of individuals who did not receive physiotherapy. One fifth of physiotherapy recipients stated a subjective benefit (16/82, 19.5%) of physiotherapy. A total of 29.4% (5/17) of respondents with mild DCM (mJOA ≥ 15) perceived benefit from physiotherapy, compared to 29.0% (9/31) of respondents with moderate DCM (mJOA 12-14), and 5.9% (2/34) of respondents with severe DCM (mJOA ≤ 12). Those perceiving benefit from physiotherapy had significantly higher mJOA scores than those that did not perceive benefit (P = .032). Current neck pain scores were significantly lower in those that perceived benefit (3.9 ± 2.9 vs 5.7 ± 2.4, P = .031). In multivariate logistic regression analysis, disease severity (classified by mJOA score) was independently associated with perceived benefit from physiotherapy. Those with mild DCM (mJOA >14) were more likely to perceive benefit from physiotherapy than those with severe DCM (mJOA <12; OR = 28.5, 95% CI = 2.0 – 410.8, P = .014). Those with moderate DCM (mJOA 12-14) were also more likely to perceive benefit from physiotherapy than those with severe DCM, however, to a lesser extent (OR = 12.7, 95% CI = 1.3-126.2, p = .030). Individuals who waited 1-2 years to receive a diagnosis of DCM were less likely to perceive benefit from physiotherapy than those that waited 0-6 months (OR: .04, 95% CI = < .01-.8, P = .035). Receiver operating characteristic (ROC) curve analysis showed the area under the ROC curve (AUC) was .866, reflecting excellent predictive performance of the model. Conclusion: The provision of non-operative physiotherapy in the management of DCM is inconsistent and appears to differ from international guidelines. Few perceived benefit from physiotherapy, however, this was more likely in those with mild DCM and in those with shorter symptom durations. Further work is needed to establish the appropriate role of physiotherapy for this population.

1078

P144: C1 Laminoplasty Using New Titanium Plate for Retro-Odontoid Pseudotumor

Seishi Matsui ^1,2 , and Naoki Shinohara ¹

¹ HITO Hospital, Neurosurgery, Shikokuchuou City, Japan

² Kajiura Hospital, Neurosurgery, Matsuyama City, Japan

Introduction:For retro-odontoid pseudotumor, the effectiveness of some surgical procedures, such as direct resection, atlantoaxial fusion, C1 laminectomy with or without fusion, C1 laminoplasty, have been reported, but an appropriate surgical therapeutic strategy for the disease has not been established. The direct resection seems to be technically difficult and the fusion surgery makes loss of C1/2 motion. C1 laminectomy without fusion has a potential risk of C1 anterior arch fracture. The aim of this study was to report surgical outcome of C1 laminoplasty using a newly designed titanium plate (Basket-2) for retro-odontoid pseudotumor. This titanium plate, produced for double-door cervical laminoplasty, was a basket-shaped spacer with two short arms with screw hole, and easily fixed to the laminar flap with 5-mm or 7-mm length screws. Material and Methods:Four male patients (range in age: 60-84 years-old) with retro-odontoid pseudotumor without obvious atlantoaxial subluxation were reviewed. Three patients underwent C1 double-door laminoplasty using the titanium plate and one patient with thick posterior arch underwent C1 laminotomy for decompression followed by the plate fixation into the laminotomy space. All patients had additional subaxial cervical laminoplasty for compressivemyelopathy caused by ossification of the posterior longitudinal ligament in two patients and spondylosis in two. The follow-up period was at least 10 months. The Neurosurgical Cervical Spine Scale score (NCSS score) was used for neurological assessment.Results:There was no peri- and postoperative complications. All patients showed neurological improvement following surgery, the NCSS score improved from 6.8±2.2 to 9.5± 1.3.Conclusion:C1 laminoplasty using new titanium plate seemed to be a therapeutic option for retro-odontoid pseudotumor without obvious atlantoaxial subluxation, however further follow-up is needed for the accurate evaluation of this procedure.

1198

P145: The Impact of Phophodiesterase Inhibition on Neurobehavioural Outcomes in Preclinical Models of Traumatic and Nontraumatic Spinal Cord Injury: A Systematic Review of the Literature

Max Butler ¹ , Oliver Mowforth ¹ , Faheem Bhatti ¹ , Jye Quan Teh ¹ , Ben Grodzinski ¹ , Melika Akhbari ¹ , Benn Walker ² , Luke Ottewell ³ , Sylva Adeeko ⁴ , Rory Dilworth ⁴ , Aniqah Bhatti ¹ , Unaiza Waheed ⁵ , Sophie Robinson ⁶ , Temi Osunronbi ⁷ , Gayathri Suresh ¹ , Isla Kuhn ⁸ , Benjamin Davies ¹ , and Mark Kotter ¹

¹ University of Cambridge, Division of Neurosurgery, Department of Clinical Neurosciences, Cambridge, United Kingdom

² University of East Anglia, Norwich, United Kingdom

³ Unversity of Bristol, Bristol, United Kingdom

⁴ University of Warwick, Warwick, United Kingdom

⁵ University of Exeter, Exeter, United Kingdom

⁶ University of Glasgow, Glasgow, United Kingdom

⁷ University of Plymouth, Plymouth, United Kingdom

⁸ University of Cambridge, Medical Library, Cambridge, United Kingdom

Introduction: The objective of this study is to evaluate the impact of phosphodiesterase (PDE) inhibitors on neurobehavioural outcomes in preclinical models of nontraumatic and traumatic spinal cord injury (SCI). Material and Methods: A systematic search was performed of MEDLINE and Embase databases. Studies were included if they evaluated the impact of PDE inhibitors on neurobehavioral outcomes in preclinical models of nontraumatic and traumatic SCI. Data were extracted from relevant studies, including sample characteristics, injury model, and neurobehavioural assessment techniques and findings. This systematic review was conducted following PRISMA guidelines. To assess the risk of bias the SYRCLE checklist was used. The review was registered with PROSPERO (CRD42019150639). Results: The search yielded a total of 1537 papers. Twenty-one papers met the inclusion criteria. Sample sizes for neurobehavioural assessments ranged from 11 to 144. The PDE inhibitors used were rolipram (n = 17), cilostazol (n = 3) and PDE-I (n = 1). The injury models used were traumatic SCI (n = 17), spinal cord ischaemia (n = 3), and degenerative cervical myelopathy (n = 1). The most commonly assessed outcome measures were BBB (Basso, Beattie, Besnahan) locomotor score (n = 12) and grid walking (n = 7). Of the twelve studies assessing BBB score, nine studies involved animals treated exclusively with rolipram. Three of these nine studies found that rolipram-treated animals had significantly higher BBB scores than vehicle-treated animals. Individual studies found BBB scores were significantly higher than vehicle-treated animals when rolipram was combined with: stem cells with cAMP, Nogo-66 receptor protein, methylprednisolone, and stem cells with GFP. In contrast, three studies found BBB scores were not significantly different to vehicle-treated animals when rolipram treatment was combined with: clodronate, Schwann cells with or without cAMP, and cAMP alone. Of studies assessing BBB subscore, five studies involved animals treated exclusively with rolipram, two of which found animals treated with rolipram alone had significantly higher BBB subscores than vehicle-treated animals. Seven studies assessed grid walk performance. In five studies involving exclusive rolipram treatment, two found that rolipram treated rats had significantly fewer footfall errors than vehicle-treated rats. Two studies assessed allodynia; one found that PDE4-I treatment significantly reduced mechanical allodynia four weeks post-SCI, while another found no significant change in mechanical allodynia following exclusive treatment with rolipram. In three studies that performed gait analysis, no significant difference was observed in foot exrotation (2/2) base of support (3/3), or stride length (3/3) between rolipram and vehicle-treated animals. Three studies used the modified Tarlov score in their assessments, each using a spinal cord ischaemia injury model, and cilostazol treatment; one of these studies found a significant improvement in Tarlov score with cilostazol treatment. Conclusion: In preclinical models of traumatic and nontraumatic SCI, the role of PDE inhibition is uncertain. Whilst some studies have shown benefit across a range of neuromuscular outcomes, this is not consistent with others unable to detect a significant change.

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P146: New Device for Safe and Efficient Osteophyte Removal During Anterior Cervical Corpectomy and Fusion (ACCF) Procedures: Technique Description and Case Series

Hani Malone ¹ , Michael Millgram ² , Richard Guyer ³ , Ran Harel ⁴ , and Ely Ashkenazi ²

¹ Scripps Clinic Torrey Pines, La Jolla, CA, USA

² Assuta Medical Center, Israel Spine Center, Tel Aviv, Israel

³ Texas Back Institute, Plano, TX, USA

⁴ Sheba Medical Center, Spine Surgery Division, Ramat Gan, Israel

Introduction: Anterior Cervical Corpectomy and Fusion (ACCF) is an effective technique to address multi-level cervical spondylotic myelopathy. However, as the number of surgical levels increases, the outcomes worsen with respect to complication rates, range of motion, and length of surgery. The aim of this study was to determine the clinical outcome of ACCF procedures conducted using a new distally curved and shielded drilling device, designed to reduce the number of resected vertebral bodies in the presence of dorsal osteophytes on multiple consecutive cervical vertebrae. The device facilitates efficient osteophyte removal at levels adjacent to a resected vertebra, enabling a safer and shorter procedure while preserving spinal stability and range of motion. Material and Methods: A retrospective study was conducted using the records of thirty-eight patients treated for osteophyte removal using the device during ACCF procedures. Most patients were otherwise candidates for an additional adjacent corpectomy or discectomy. Following vertebral body removal, the device was inserted via the vertebral trough anterior to the posterior longitudinal ligament and used to drill parallel to the thecal sac, into the osteophytes, and not behind them as current devices necessitate. Clinical outcome was evaluated using patient back and arm pain scores and SF-36 questionnaires. Results: All procedures were uneventful and without major complications. The average surgery time was 77.5 minutes. The average hospitalization duration was 3.4 days. Osteophyte removal, as verified by intraoperative O-arm CT imaging, was satisfactory. On average, Patient back and arm VAS scores were improved by 1.2 and 1.5 points, respectively (P = .1). Patient disability was improved as indicated by the SF36 scores, which were improved in all domains. Conclusion: The presented device enabled safe and efficient removal of osteophytes sparing adjacent vertebral removal in ACCF procedures, thus improving the clinical outcome.

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P147: Developing Spinal Researchers of Tomorrow: Initial Results From Collaborative Systematic Reviews Using a National Student Network

Faheem Bhatti ¹ , Oliver Mowforth ¹ , Max Butler ¹ , Isla Kuhn ¹ , Mark Kotter ¹ , and Benjamin Davies ¹

¹ University of Cambridge, Neurosurgery, Cambridge, United Kingdom

Introduction: Undergraduate medical curricula feature little research methodology. Systematic Reviews (SRs) are the first step in clinical research but are time consuming and often left unfinished by students. We hypothesised that a collaborative, educational approach to SRs, whereby medical students with little or zero research experience work together under supervision of postgraduate researchers may improve student experience, in terms of training and efficient search. Material and Methods: A post-graduate team led 14 medical students working on 2 neurosurgical SRs on the topic of degenerative cervical myelopathy. Students were trained on the SR background, inclusion/exclusion criteria and collaborative screening. Rayyan software enabled the search strategy to be portioned amongst reviewers. A screening pilot of 100 articles compared student performance to ‘gold-standard’ post-graduate results. Students completed pre-project questionnaires on their research background, perceptions, knowledge, confidence and experience. Questions were scored on numeric rating scales of 1 (lowest score) to 10 (highest score). Material and Methods: Average pre-project questionnaire scores showed students were excited to be involved (9.1) but had poor experience (3.9) and confidence conducting SRs (5.4). Students were satisfied with the guidance provided (8.2) and enjoyed being involved (8.2). Students felt a collaborative SR would improve their understanding of research (9.5) and was a good way to build skills, experience and confidence for future SRs (9.4). Agreement between medical students and post-graduate researchers was 98% in pilot screening. Conclusion: This approach appears an effective method of making large SSCs manageable and providing students with research training and experience. Mid-screening, post-screening and post-project questionnaires will further evaluate this approach as the SR continues.

1359

P148: Comparison of Patient-Reported Postoperative Dysphagia in Patients Undergoing One-Level Versus Two-Level Anterior Cervical Discectomy and Fusion with Zero-P Implant System

Chengyi Huang ¹ , Hao Liu ¹ , Beiyu Wang ¹ , Chen Ding ¹ , and Yang Meng ¹

¹ West China Hospital, Sichuan University, Orthopedics, Chengdu, China

Introduction: We hypothesize that a greater number of surgical levels may result in a higher incidence of dysphagia due to more dissection of soft tissue, although whether the incidence of postoperative dysphagia differs between these procedures in anterior cervical discectomy and fusion (ACDF) with the Zero Profile (Zero-P) Implant System is unknown. Thus, the purpose of this retrospective study was (1) to investigate whether the incidence of postoperative dysphagia differs between one-level and two-level ACDF with the Zero-P and (2) to examine patient characteristics that may be associated with the occurrence of dysphagia after ACDF with the Zero-P. Material and Methods: A retrospective analysis of 208 patients who underwent ACDF with the Zero-P Implant System and had at least one year of follow-up was performed from January 2013 to December 2018. The patients were divided into two groups based on the number of operated levels (one-level group, N = 86; two-level group, N = 122). Dysphagia was assessed based on the Bazaz grading system. The incidence of dysphagia and the severity of dysphagia at each follow-up were compared between the two groups. The patients were divided into two groups (nondysphagia group, N = 160; dysphagia group, N = 48), and covariates were obtained for multivariate analysis, including demographic parameters, surgical parameters, and radiographic parameters. Results: The results showed that the incidence and severity of postoperative dysphagia in the two-level group were significantly greater at 1 week, 1 month and 3 months postoperatively than those in the one-level group. The results of ordinal logistic regression showed that older age, two-level surgery, greater prevertebral soft tissue swelling (PSTS) and the difference between the postoperative and preoperative C_2-7 angle (dC_2-7A) were significantly associated with a higher incidence of dysphagia after ACDF with the Zero-P. Conclusions: Two-level ACDF with the Zero-P can result in a significantly greater incidence and severity of transient postoperative dysphagia. Older age, greater PSTS and the dC_2-7A were also associated with postoperative dysphagia after ACDF with the Zero-P.

1394

P149: Parkinson's Disease, Dysphagia and Cervical Spine Surgery

Mauricio Avila ¹ , Pedro Aguilar-Salinas ¹ , Aaron Burket ¹ , and Travis Dumont ¹

¹ University of Arizona, Neurosurgery, Tucson, USA

Introduction: Cervical Spondylotic myelopathy (CSM) is an increasingly common problem in the aging population. Several surgical options exist to treat this condition including anterior, posterior and combined surgical approaches. Each approach carries its own set of postoperative complications with the anterior approach having a known risk of postoperative dysphagia. Little is known of the of outcomes after cervical spine surgery in Parkinson's disease (PD). In this work we evaluated the rate of dysphagia for PD patients undergoing cervical spine surgery for CSM. Methods: The National Inpatient sample was queried 1998-2016 and all elective admissions with cervical spondylotic myelopathy were identified. Surgical treatments were identified as either: anterior cervical discectomy and fusion (ACDF), posterior laminectomies, posterior cervical fusion or combined anterior/posterior surgery. Pre-existing PD was identified. Endpoints included mortality, length of stay (LOS), swallowing dysfunction measured by placement of feeding tube, and post-procedure pneumonia. Results: A total of 73 088 patients underwent surgical procedures for CSM during the study period. Of those, 552 patients (7.5%) had concomitant PD. The most common procedure overall was ACDF. Patients with PD who underwent ACDF, posterior laminectomies or posterior cervical fusion had a longer LOS compared to those who did not have PD (P < .001). There was no difference in LOS for patients who underwent combined anterior/posterior surgery. Inpatient mortality was higher in patients with PD who underwent ACDF or combined surgery (P < .001). Patients with PD had a higher rate of a nasogastric tube placement after surgery (dysphagia) compared with those without PD (P < .001). Multiple regression analysis showed that PD patients had a higher risk of having NG Tube placement or developing pneumonia (OR 2.98 [1.7-5.2], P < .001) after surgery. Conclusions: While ACDF is the most commonly performed procedure for CSM in patients with PD, it is associated with longer LOS, higher incidence of postoperative dysphagia, and post-procedural pneumonia, as well as higher inpatient mortality compared with posterior cervical procedures.

1425

P150: Effect of Autograft Utilization on Patient Reported Outcomes Following Anterior Cervical Discectomy and Fusion

Ivan Zapolsky ¹ , Lauren Boden ¹ , Amrit Khalsa ¹ , and Comron Saifi ¹

¹ University of Pennsylvania, Orthopaedic Surgery, Philadelphia, USA

Introduction: Utilization of iliac crest autograft bone, cortical, morselized or marrow aspirate, to enhance fusion in anterior cervical discectomy and fusion (ACDF) is a well-established surgical technique. This practice has been associated with higher rates of fusion than those seen with allograft alone. It has been well documented that autograft harvest is associated with postoperative pain and harvest site wound complications. Despite this widespread utilization, there is a paucity of data regarding the effect of autograft harvest and utilization of autograft on patient reported outcome measures (PROMIS) following ACDF. The purpose of this study was to examine the short-term patient reported outcomes following ACDF with or without autograft harvest performed in conjunction with their procedure. Material and Methods: All ACDF procedures performed by neurosurgeons and orthopaedic spine surgeons at a single institution were collected during the calendar year of 2019. Of those, 59 had computer assisted testing patient reported outcomes obtained pre and post operatively, with post-operative scores obtained at an average of 8 weeks after surgery. This time point was chosen to isolate for the effect of graft harvest on outcome scores in the acute post-operative period. Change in PROMIS scores for pain, physical function and depression were compared between the autograft and allograft groups. Results: Preoperative pain, physical function, and depression scores were not statistically different between groups. While post-operative PROMIS pain scores improved in both the allograft (−4.3, P = .019) and autograft (−8.2, P = .004) groups, there was no significant difference in the amount of improvement (Figure 1). There was a significant improvement in post-operative depression score in the autograft group, (−6, P = .04) that was not seen in the allograft group, and the average postoperative depression score in the autograft group was significantly lower than that of the allograft group (43 vs 51, P = .007). Conclusion: Our data suggests that while autograft donor site pain is a common complaint following ACDF, PROMIS scores do not reflect an advantage to the use of allograft with respect to reduction in patient reported post-operative pain. Beyond the known economic and clinical benefits of decreased cost and increased rates of fusion, this data further bolsters the usage of autograft in ACDF procedures.

1543

P151: Carbon Fiber Versus PEEK Cages in 3-Level Anterior Cervical Discectomy and Fusion: a 2-Year Follow-Up Study with Clinical and Radiological Outcomes

Daniel Coban ¹ , Stuart Changoor ¹ , Conor Dunn ¹ , Michael Pompliano ¹ , Kumar Sinha ¹ , Ki Hwang ¹ , Michael Faloon ¹ , and Arash Emami ¹

¹ St. Joseph's University Medical Center, Paterson, NJ, USA

Introduction: Anterior cervical discectomy and fusion (ACDF) has widely been accepted as the standard treatment for cervical disc disease. To avoid complications related to the use of autograft for fusion, stand-alone devices such as Polyetheretherketone (PEEK) and carbon fiber composite (CFC) cages have been developed as a substitute to achieve bony union. PEEK implants offer the benefits of thermo-resistance and sufficient biocompatibility. However, CFC implants have gained increased acceptance as an alternative to metal and PEEK biomaterials owing to optimal visualization on imaging and high rates of fusion. Although a number of studies have investigated cage types in single and two-level ACDF, there has been a paucity of reports in the literature comparing these devices in multilevel anterior cervical fusion. Therefore, the purpose of this study was to retrospectively analyze the long-term radiographic and clinical outcomes of CFC versus PEEK cages in 3-level ACDF. Material and Methods: A retrospective review was performed to identify all patients between 2013-2018 who underwent 3-level ACDF with either a carbon fiber or PEEK cage and a minimum follow-up of 2 years. Demographic data was recorded and compared between both cohorts. Revision rates, time to revision, and graft subsidence in each group were also compared. Pre-operative and post-operative changes in cervical lordosis and disc height were also measured radiographically. Functional outcomes were assessed with NDI, VAS-n and VAS-a measurements at follow-up visits. Results: A total of 76 patients were included, 34 in the CFC cohort and 42 in the PEEK cohort. Mean follow-up of the CFC and PEEK cohorts were 44.5 and 41.8 months, respectively. The overall revision rates were 14.7% for the CFC cohort and 4.8% for the PEEK cohort (P = .136). Mean time to revision was 302 ± 128.7 days and 596.4 ± 220 days for the PEEK and CFC groups, respectively (P = <.001). Of those patients who had a revision surgery, 40% in the CFC and 50% in the PEEK group were smokers, respectively (P = .809). The graft subsidence rates for the CFC and PEEK groups were 11.8% and 14.0% at final follow-up (P = .777). In all cases, the cervical lordosis was at least maintained or corrected and disc heights were restored. There were 16 males and 18 females in the CFC cohort compared to 19 males and 23 females in the PEEK cohort (P = .874). Both groups experienced significant improvements in their functional outcome scores compared to their pre-operative values; however, there were no statistically significant improvements between groups with the exception of VAS-arm scores at final follow up (CFC 3.1; PEEK 4.1; P = <.001). Conclusion: The radiological and clinical results were similar between the CFC and PEEK groups. The overall revision rate was higher in the CFC group and the subsidence rate at final follow-up was higher for the PEEK group; however, these differences were not significant. Smoking was a predictive factor for revision surgery. In conclusion, both CFC and PEEK implants showed positive outcomes in terms of functional scores as well as restoration of cervical lordosis and disc height.

1553

P152: Two Attending Surgeons Improve Outcomes of Anterior Cervical Discectomy and Fusion

Michael Faloon ¹ , Stuart Changoor ¹ , Nikhil Sahai ¹ , Conor Dunn ¹ , Kumar Sinha ¹ , Ki Hwang ¹ , and Arash Emami ¹

¹ St. Joseph's University Medical Center, Paterson, NJ, USA

Introduction: ACDF is one of the most common procedures performed by spine surgeons, but it is not without complications. The involvement of a two-attending surgeon team has been shown to have improved perioperative outcomes in complex spine procedures such as deformity correction. The purpose of this study was to assess the effect of two attending surgeons on patients undergoing single level ACDF procedures. Material and Methods: A retrospective matched cohort study of patients undergoing 1-level ACDF for degenerative cervical spondylosis, with minimum 2-year follow-up. Patients were subdivided into 2 cohorts: (A)cases performed by one attending surgeon assisted by resident, fellow, physician assistant or other medical staff, and (B)cases performed by an attending surgeon with another attending surgeon as first-assist. Patients were matched by age, sex, BMI, ASA and CCI. Perioperative data including anesthesia, surgical time, blood loss, postoperative complications and rate of fusion were compared. Standard binomial and categorical comparative analysis were performed. A p-value <.05 was deemed significant. Results: 42 patients were included (21 in each group). There were 22 males and 20 females, with a mean age of 47.7 years and mean follow-up of 43.4 months. There were no differences in any demographic variable between the two groups, indicating successful matching. Cohort B had decreased anesthesia time (114.9 vs 157.1 minutes, P < .001), operative time (58.1 vs 98.9 minutes, P < .001) and blood loss (14.8 vs 24.3 mL, P = .012). There were no significant differences in terms of post-operative complications including dysphagia, wound infection, neurologic or cardiovascular related complications. All patients achieved successful fusion at final follow-up. Conclusion: A two-attending surgeon team significantly reduces anesthesia time, surgical time, and blood loss, in 1-level ACDF procedures, without an increase in complications, or decrease in fusion rates, further highlighting the benefit of having two experienced surgeons present in these procedures.

1554

P153: Allograft Cellular Bone Matrix as an Augment in 3-Level Anterior Cervical Discectomy and Fusion

Stuart Changoor ¹ , Conor Dunn ¹ , Nikhil Sahai ¹ , Kumar Sinha ¹ , Ki Hwang ¹ , Michael Faloon ¹ , and Arash Emami ¹

¹ St. Joseph's University Medical Center, Paterson, NJ, USA

Introduction: Cervical spondylosis is one of the most common pathologies encountered by spine surgeons. The gold standard surgical treatment is anterior cervical discectomy and fusion (ACDF), however consistently high fusion rates can be difficult to achieve as the number of levels involved increases. Autograft used as a fusion augment, comes with its own complication profile. Therefore, alternatives such as off-label use of bone morphogenic protein, have been implemented in an attempt to increase fusion rate. However, since its introduction, allograft cellular bone matrix (ACBM) has been used in many orthopedic procedures due to its osteogenic, osteoconductive and osteoinductive properties. The literature is lacking in studies focused on the effect of ACBM in complex multilevel cervical fusion procedures. The purpose of this study is to investigate the safety and efficacy of ACBM in complex 3-level ACDF procedures. Material and Methods: A retrospective review was performed to identify patients who underwent 3-level ACDF with ACBM as an augment since 2014, with a minimum follow-up of 2 years. Patient functional outcomes were assessed with VAS-arm, VAS-neck and NDI scores pre- and post-operatively. Complications including dysphagia, wound related, and implant related were recorded. Radiographs were analyzed for fusion and adjacent segment degeneration (ASD). Results: 67 patients (201 total instrumented levels) were included, 36 male and 31 female, with a mean age of 57.6 years and a mean follow-up of 45.4 months. 25.3% of patients were diabetic and 23.9% of patients were smokers. Patients experienced significant improvements in VAS-arm, VAS-neck and NDI scores at 2-year follow-up compared to their pre-operative scores (P < .001). 24 patients (35%) reported post-op dysphagia, all of which resolved by 6-month follow-up. There were 2 cases (4.4%) of wound related complications. 3 patients (4.4%) had implant complications requiring subsequent removal of implants or screws. There were 6 cases (8.9%) of ASD diagnosed on post-operative radiographs, and 4 patients (5.9%) were noted to have evidence of pseudarthrosis at 2-year follow up. Conclusion: Patients undergoing complex 3-level ACDF procedures augmented with ACBM had significant improvement in functional outcomes and high fusion rates, with a relatively low complication profile. ACBM may be an effective alternative to autograft in these complex procedures.

1567

P154: Cervical Disc Replacement Versus Minimally-Invasive Posterior Cervical Foraminotomy in the Treatment of Cervical Radiculopathy

Stuart Changoor ¹ , Conor Dunn ¹ , Nikhil Sahai ¹ , Kumar Sinha ¹ , Ki Hwang ¹ , and Arash Emami ¹

¹ St. Joseph's University Medical Center, Paterson, NJ, USA

Introduction: Degenerative disease of the cervical spine is frequently encountered by spine surgeons, especially as the elderly population increases. Anterior cervical discectomy and fusion (ACDF) is one of the most common procedures performed to address this pathology, but it is not without complications. Adjacent segment degeneration is one such complication that is often associated with the loss of a motion segment. Pseudarthrosis is another complication that spine surgeons aim to avoid. As a result, motion preservation techniques such as cervical disc replacement (CDR) and minimally-invasive posterior cervical foraminotomy (MI-PCF) have been used as an alternative to ACDF with the goal of decreasing fusion related complications. However, there is a paucity of literature comparing these two procedures in the treatment of cervical radiculopathy. The purpose of this study is to compare the motion preserving techniques of CDR and MI-PCF in the treatment of single-level cervical radiculopathy. Material and Methods: A retrospective review was performed to identify all patients who underwent either single-level CDR or MI-PCF for single-level unilateral cervical radiculopathy due to lateral pathology from 2012 to 2017 with a minimum follow-up of 2-years. Patients with myelopathy were excluded. Demographic data were recorded and analyzed. Improvement in functional outcome scores were compared between both cohorts. Revision rate, as well as average time to revision, were also compared. All complications were reviewed. Standard binomial and categorical comparative analysis were performed. Results: 119 patients were included in the study with an average follow-up of 49.2 months. 57 patients underwent CDR and 62 patients underwent MI-PCF. There were no significant differences in age, sex or BMI between the two cohorts. Both cohorts experienced significant improvement in all functional outcome scores (NDI, VAS-arm, VAS-Neck). There was no significant difference between the revision rates of the CDR and MI-PCF cohorts (3.5 vs 6.4%, P = .68). The average time to revision of the CDR cohort was 10.5 months, while the MI-PCF cohort was 12.4 months (P = .28). The most common complication of CDR was subjective post-operative dysphagia, while the most common complication of MI-PCF was transient neuropraxia, all of which resolved by final follow-up. Conclusion: The results from our study suggest that CDR and MI-PCF are effective in treating patients with unilateral cervical radiculopathy without myelopathy. They resulted in significant improvements in clinical outcome scores with a low revision rate. In the right patient, CDR and MI-PCF can be effective motion preserving alternatives to ACDF to avoid fusion related complications.

1568

P155: Comparing Long-Term Outcomes Between ACDF and Minimally-Invasive Posterior Cervical Foraminotomy in the Treatment of Cervical Radiculopathy

Stuart Changoor ¹ , Conor Dunn ¹ , Nikhil Sahai ¹ , Kumar Sinha ¹ , Ki Hwang ¹ , Michael Faloon ¹ , and Arash Emami ¹

¹ St. Joseph's University Medical Center, Paterson, NJ, USA

Introduction: Minimally invasive posterior cervical foraminotomy (MI-PCF) has been shown in several studies to be equally effective as ACDF in treating cervical radiculopathy due to foraminal stenosis and similar pathologies. MI-PCF also has several advantages over ACDF in short-term follow-up as it is associated with less hardware utilization, shortened hospital stay and time away from work, reduced blood loss, medication use and cost. Additionally, it has been hypothesized that preserving motion and avoiding fusion reduces risk for adjacent level disease, but potentially increases risk for subsequent revision to an ACDF. Recent studies have shown a similar revision rates between MI-PCF and ACDF at 2-year follow-up. With similar short-term outcomes and substantial advantages, MI-PCF may be an effective alternative to ACDF for addressing appropriate cervical pathology. Therefore, to confirm this hypothesis and to justify utilization of MI-PCF over ACDF, we must determine both overall revision rates and functional outcomes with long term follow-up. Material and Methods: A retrospective review was performed to identify all patients between 2009 and 2013 who underwent either ACDF or MI-PCF with a minimum follow-up of 7-years. Demographic data was recorded and compared between both cohorts. Revision rate between ACDF and MI-PCF patients were also compared. Functional outcomes were assessed with NDI and VAS-n and VAS-a measurements at follow-up visits. All complications were reviewed. Standard binomial and categorical comparative analysis were performed. Results: A total of 177 consecutive patients were included, 143 in the ACDF cohort and 34 in the MI-PCF cohort. Mean follow-up of the ACDF and MI-PCF cohorts were 96.8 and 94.5 months, respectively. Complication rates were 4.9% and 2.9% for the ACDF and MI-PCF cohorts, respectively (P = 1). The overall revision rates were 9.1% for the ACDF cohort and 11.8% for the MI-PCF cohort (P = .745). All MI-PCF patients were revised to a fusion. There were 60 males and 83 females in the ACDF cohort compared to 29 males and 9 females in the MI-PCF cohort, a statistically significant difference (P = <.001). Both cohorts experienced significant improvements in their functional outcome scores (NDI, VAS-neck, and VAS-arm) compared to their pre-operative values, however the magnitude of improvement was not statistically significant between the ACDF and MI-PCF cohorts. Conclusion: MI-PCF is a safe and effective alternative to ACDF in the treatment of cervical radiculopathy, demonstrating long-lasting benefit. After long-term follow-up, MI-PCF demonstrated similar improvements in functional outcome scores, without increased complication or revision rates, and is associated with the advantages of decreased hospital length of stay, overall cost, and quicker return to work. Further studies should consist of cost analysis to evaluate how utilizing MI-PCF would impact overall health-care spending.

1585

P156: The Role of Metabolism in Degenerative Cervical Myelopathy: A Systematic Review

Celine Partha-Sarathi ¹ , Benjamin Davies ¹ , and Oliver Mowforth ¹

¹ Division of Neurosurgery, University of Cambridge, Department of Clinical Neurosciences, Cambridge, United Kingdom

Introduction: Degenerative cervical myelopathy (DCM) is the commonest cause of adult spinal cord impairment worldwide, encompassing chronic compression of the spinal cord, neurological disability and diminished quality of life. The role of metabolic factors in DCM is currently unknown; elucidation may prove beneficial in improving understanding and management of the condition. The objective was therefore to synthesise current evidence on the effect of metabolism on DCM susceptibility, severity and surgical outcome. Methods: A systematic review in MEDLINE and Embase was conducted following PRISMA guidelines Full-text papers in English, with a focus on cervical myelopathy and metabolism, such as diabetes, cardiovascular disease, anaemia and lipid profiles published before January 2020 were included. Quality assessments of the papers were performed using the Downs and Black tool and the GRADE assessment tool. Patient demographics, metabolic factors and outcomes assessed were recorded. Relationships between metabolic factors and interventions and disease prognosis were assessed. The results were separated depending on whether they discussed effects on spinal cord disease, spinal column disease or adverse, post-operative outcomes. Results: A total of 5835 papers were identified, of which 51 were included in the final analysis. DCM patients with history of diabetes or cardiovascular disease were more likely to experience poorer post-operative symptom improvements, greater perioperative morbidity and higher rates of complications. They were also more likely to have comorbidities such as obesity and hyperlipidaemia. There appears to be a significant negative relationship between duration of diabetes and surgical outcome. Lipid profiles were shown to be dysregulated in patients with spinal cord injury. Anaemia was shown to be highly prevalent in DCM patients and was associated with perioperative complications and poor post-operative neurological function. Conclusion: Metabolic factors appear highly relevant to surgical outcomes in DCM. Evidence for a role of metabolic factors in predicting DCM susceptibility and severity is sparse. Further characterisation of the role of metabolism in DCM may prove useful in understanding risk factors for disease development and in prognostic stratification of patients.

1667

P157: Atlantoaxial Osteoarthritis (AAOA)—Natural History and Clinical Outcomes of Conservative Treatment

Mirant Dave ¹ , Bharat Dave ¹ , Ajay Krishnan ¹ , Devanand Deglumadi ¹ , Shivanand Mayi ¹ , and Raviranjan Rai ¹

¹ Stavya Spine Hospital and Research Institute Pvt., Ahmedabad, India

Introduction: The C1–C2 joint is a three-joint complex, while the other cervical joints below make a five-joint complex, making the atlantoaxial joints undergo increased stress biomechanically. Atlantoaxial Osteoarthritis (AAOA) is a known entity amongst elderly age group. Patients typically present with suboccipital headache, neck muscle spasm and unilateral restricted movement of the neck. The purpose of this study is to share our experience, acknowledge this condition and its natural history and related review of literature. Material and Methods: Ethical approval was obtained from Stavya Spine Hospital and Research Institute Ethics Committee. 338 patients were collected from the database, 250 patients responded for follow up. All patients presented with occipital neuralgia and unilateral restriction of rotation with normal neurology. The average age of the patients was 65 years (57–80 years). The patients were followed up for a minimum of 18 months. All patients were managed conservatively, treated with cervical collar and/or steroid injection or surgery, only if required. Indication for arthrodesis was pain, not responding to conservative management. The diagnosis of AAOA was confirmed with an open mouth view, dynamic flexion extension radiographs and a CT scan for operative management. Patients with poor outcomes were divided into two groups, the first group was injected with an intraarticular cocktail of 40 mg Triamcinolone, with 1 ml, .5% Sensorcaine, under C-Arm guidance. The second group was injected with the same cocktail over the Greater occipital nerve, 2 cm away from midline, on the painful side. Results: Majority of the patients (200) were females working as house wife, while 50 were males. We did not find any correlation with work, especially lifting heavy weight on the head (Indian lifestyle), did not corelate with pain and arthritis. 196 patients had excellent outcome with cervical collar only, while 51 patients had poor outcome, 3 patients had fair outcome. Out of the 51 patients with poor outcome, 20 patients were treated with cocktail injection, 6 patients were treated surgically, while 25 patients elected to wear cervical collar. Out of the 20 patients treated with cocktail injection, 6 patients were given intraarticular cocktail injection, while 14 patients were treated with the greater occipital nerve block. Forteen patients (4 from the intra-articular group and 10 from the greater occipital group) had good relief. Only 6 patients underwent surgical fusion (3 Transarticular and 3 Harms/Goel Fusion). We observed symptomatic relief in 78.4% of the patients with cervical collar only. Majority of the patients with post treatment CT Scans were suggestive of auto-fusion of the joint, suggesting the self-limiting nature of the disease. Conclusion: Atlantoaxial Osteoarthritis is not uncommon, especially in elder women. Non-surgical treatment with cervical collar is the primary management, which provides excellent outcomes. Intra-articular or Greater Occipital Nerve Block provide good to excellent outcomes. Instability should be carefully evaluated, which can be managed conservatively. Natural history of this condition is suggestive of auto-fusion of the atlantoaxial joint and excellent relief of symptoms with or without surgical intervention.

1759

P158: Tandem Spinal Stenosis-Analysis of 60 Cases Treated BT Staged Surgery—Is Simultaneous Surgery Justified?

Rushama Tandon ¹

¹ Northern Railway Central Hospital, Orthopedics, New Delhi, India

Introduction: Tandem Stenosis (Combined, simultaneous, concomitant, concurrent) refers to stenosis occurring at the same time in the cervical and lumbar spine with cord compression due to the mobility of cervical and lumbar segments. Spondylytic degenerative changes cause clinical symptoms characterized by the triad of Intermittent neurogenic claudication, progressive gait disturbance and Myelopathy / Polyradiculopathy of both upper and lower limbs. TSS of the cervical and lumbar spine occurs in 5–25% of patients with dominating clinical symptoms of compression in one of the spinal segments. Materials and Methods: 60 patients of tandem stenosis needing surgery were evaluated. Patients presenting with degenerative stenotic symptoms over the age of 25 years with cervical, dorsal and lumbar stenosis, DISH syndrome and OPLL were included; Patients of Demyelinating diseases of the Central nervous system and Extensive brain atrophy were excluded. Preoperative and postoperative parameters of evaluation were: Pain (VAS) scale, Neck Disability Index (NDI), Oswestry Disability Index (ODI), Nurick’s Grading, X-rays of spine and chest, MRI of affected area and screening of whole spine, CT spine and Electrophysiological studies (EMG/NCV). In the cervical surgery first group, the main symptoms were upper motor neuron signs with a spinal canal equal to or less than 10 mm in anteroposterior diameter. In the lumbar surgery first group, radiculopathy and neurogenic claudication of lower extremities predominated with a canal below 11 mm in depth. Staged Posterior or Anterior decompressive surgery was performed in all cases and some type of posterior or anterior instrumentation was used in most. Results: Mean age was 45.0 (± 8.83) years; Diabetes mellitus and hypertension the common comorbidities and 36.7% had symptoms of TSS since 3 years; Upper limb symptoms appeared first compared to the lower limb and simultaneous appearance of symptoms. In Cervical stenosis 60% had grade 2 stenosis, 35% had grade 3 stenosis and 5% had grade 1 stenosis; Cervical Stenosis was due to OPLL in 20%, cervical spondylotic myelopathy in 76.6%; Lumbar stenosis was degenerative in 71.6%. 46.7% of the cases had grade B lumbar Stenosis and 36.7% had grade C lumbar Stenosis. 93.3% of the patients underwent cervical surgery first. The average duration between cervical and lumbar surgery was 1 year. The mean scores before and after surgery were as follows -VAS-6.88/1.7 which was statistically significant, Neck disability index-39.43/5.98, Oswestry disability index was 50.5/33.18 which was statistically significant; Nurick’s grading was 3.72/1.58 which is statistically significant. Mean cervical diameter improved from 10.02 to 14.1 and mean lumbar diameter from 9.35 to 11.32 mm which is statistically significant. Conclusion: This study was mainly undertaken to study the functional recovery of patients suffering from TSS. Staged surgery is promising in patients who showed significant improvement in VAS scores, Oswestry Disability index, Neck disability index, Nurick’s index and Absolute canal diameter on follow up. Staged surgery is the best option. Some patients did not require the second surgery, especially those with primary cervical surgery. There is very little argument for simultaneous decompression except in cases of spinal instability.

1782

P159: To Analyze the Radiological Phenotype, Patient and Surgery-Related Risk Factors Affecting Post-Operative Clinical Outcome for Cervical Myelopathy Due to Ossification of Posterior Longitudinal Ligament Involving C2 After Posterior Instrumented Laminectomy and Fusion

Ajoy P Shetty ¹ , Neerav Anand Singh ¹ , Rishi Kanna ¹ , and Shanmuganathan Rajasekaran ¹

¹ Ganga Medical Center and Hospitals, Coimbatore, India

Introduction: Ossified posterior longitudinal ligament (OPLL) is a rare entity involving the cervical spine, which can cause significant compression of the spinal cord and result in cervical myelopathy. There is paucity of literature on long term surgical outcome and radiological characteristics on C2(+) OPLL. The current study was thus planned to analyze radiological characteristics of ossified posterior longitudinal ligament involving C2 (C2(+) OPLL) and surgical outcomes for cervical myelopathy following posterior decompression. Simultaneously patient and surgery related risk factors affecting clinical outcomes for cervical myelopathy were assessed. Materials and Methods: Data for 61 patients with C2(+) OPLL who underwent posterior decompression surgery with minimum 24 months follow up were retrospectively analyzed. Radiographic characteristics, K-line classification along with high intensity zones (HIZ) on MRI were analyzed. Pre-operative modified Japanese Orthopedic Association (mJOA) score was recorded. At the final follow up, mJOA score and recovery rate (RR) were used to evaluate neurological assessment. To investigate the definitive factors associated with clinical outcomes, regression analysis was performed for patient and surgery-related factors. Results: C2(+) OPLL were usually mixed followed by common type with thicker in diameter and mean number of involved segments was 4.9. The narrowest space available for cord (SAC) was located between C2 and C5, with the most stenotic area being C3-C4. The mean occupancy ratio (OR) was 40.47 ± 7.58. The mean mJOA score was 10.61 ± 2.44 pre-operatively and 15.77 ± 1.42 post-operatively, with a mean recovery rate of 70.57 ± 14.88. Neurological worsening was observed in 5 cases (8.19%), but improved in all patients gradually at the final follow-up. Multivariate linear regression analysis revealed that preoperative mJOA score was an independent predictor of final recovery rate. Conclusions: Radiologically, OPLL involving C2 level are different from OPLL at the sub-axial levels. It is important to identify preventable risk factors to avoid intra-operative complications. We found that occupancy ratio, surgery duration and blood loss were independent risk factors for intraoperative dural tear. Pre-operative mJOA score is most important independent risk factor to predict recovery rate. Posterior decompression and fusion provide a relatively safe approach and effective results when compared to other surgical modalities.

Keywords

ossified posterior longitudinal ligament (OPLL), cervical myelopathy, dural tear, cervical posterior decompression and fusion, patient-related predictable risk factors, surgery-related predictable risk factors

1812

P160: High Clinical No-Show Correlates with Worse Patient Reported Outcomes Following Anterior Cervical Discectomy and Fusion

Ivan Zapolsky ¹ , Lauren Boden ¹ , Comron Saifi ¹ , and Amrit Khalsa ¹

¹ University of Pennsylvania, Orthopaedic Surgery, Philadelphia, USA

Introduction: Patient no-show rates have been shown to have effects on clinical outcomes in numerous healthcare settings. It has also been demonstrated that outreach mechanisms and special coordination of these patients can improve both individual outcomes and overall health status. This effect has rarely been described in an orthopaedic or spine surgery population. In this study we investigated the effects of patient clinical no-show rate on post-operative patient reported outcome measures in a spine surgery population. Material and Methods: All ACDF procedures performed by neurosurgeons and orthopaedic spine surgeons at a single institution were collected over a 1-year period. Of those, 59 had computer assisted testing patient reported outcomes obtained pre and post operatively. Clinical appointment no-show rate within the entire health system was collected for all patients and classified as high if over 5% and low if under 5%. Patient reported outcomes scores and complication rates were then compared between patients with high or low clinical no-show rates. Results: Average pain, physical function and depression scores were 63 37 and 54 respectively preoperatively and 65 35 and 49 respectively postoperatively with significant improvements in Pain -6 (P > .001) and depression scores after surgery. Complication rate was 25% with 6/15 being moderate dysphagia. Average number of levels fused was 1.7. Average follow up was 58 days. Patients had a minimum of eight clinical appointments within the healthcare system (range 8-269). There was no significant difference between low and high no-show groups in complication rate, number of levels fused, average follow up or average number of clinical appointments. Subgroup analysis demonstrated pre and post-operative patient reported pain (69 vs 63, P < .001; 66 vs 56, P < .001) physical function (33 vs 37, P = .041; 32 vs 38, P = .011) and depression (59 vs 50, P < .001; 57 vs 46, P = .001) scores were significantly worse in the high no-show group as compared to the low no-show group, respectively. The low no-show group demonstrated significant improvements in pain(-6, P < .001) and depression (−4, P = .048) scores following surgical intervention while the high no-show group did not. Conclusion: Patients who regularly miss scheduled clinical appointments are an at-risk population. This study corroborates those in other fields, demonstrating worse clinical outcomes for pain physical function and depression in the high no-show population. The effect of surgery on their scores was also less robust and did not demonstrate significant improvement with surgery. While these patients may still benefit from surgical intervention, their postoperative improvements are diminished as compared than their low no-show rate counterparts. The poor clinical attendance of these patients may cause them to miss vital clinical follow-up, including relevant instructions and post-operative care critical to surgical success. Surgeons may choose to consider clinical attendance rates in patient selection for surgical intervention. Efforts might also be made to improve patient outreach to at-risk individuals as this might help to mitigate the negative effects on surgical outcomes.

1866

P161: Anterior Hybrid Fixation in Severe Multilevel Cervical Myelopathy

Ravi Venkatesan ¹

¹ Apollo Hospitals, Orthopaedics, Chennai, India

Introduction: Cervical myelopathy is one of the most prevalent causes of spinal cord dysfunction in the elderly population. The natural history is usually progressive in nature. Cause may be a spondylosis or OPLL. Management of cervical myelopathy has been an ever debatable topic with no proper consensus. Surgery is usually required to decompress the neural elements, restore lordosis and stabilise the spine to prevent additional degeneration at the affected level. Posterior approaches are usually preferred in complex cases. Anterior hybrid fixation involves corpectomy with a discectomy where the compression is restricted to the disc level; thereby reducing the chance of implant related problems. We are presenting the safety and efficacy of anterior hybrid fixation techniques in patients with symptomatic myelopathy based on functional scoring systems. Methods: The present study is done in the Department of Orthopaedics Apollo hospitals, Chennai from 2013-2017. During the study 33 patients who underwent anterior cervical hybrid fixation were studied. All the patients were followed in the immediate postoperative period, at 3months, 6 months, 12 months and 24 months to record their functional status. Results: We have conducted a study on 33 patients. The age group of the patients ranged between 29 and 69 years. The most commonly involved level is C5-C6 (60%). 40% of cases were due to CSM, 60% were due to OPLL. All 33 patients underwent surgery with anterior hybrid fixation. The mean blood loss was 104.8 ± 63 ml, operative time 148.86 ± 32.8 min and duration of hospital stay was 3.91 ± 1.9 days. The functional Nurick score improved from mean of 2.42 pre operatively to 1.33 at follow up and the mJOA score improved from a mean of 11 pre-operative to 15.52 at 24 weeks follow up. Age and duration of symptoms did not play a role in influencing the functional status. Complications were observed in 3 patients who had intraoperative dural tear which were repaired. Conclusion: Anterior hybrid fixation technique is an effective and safe method of management in complex cervical cases. Anterior techniques gives better results because we remove pathology, there is a better chance of fusion and neurological recovery. Kyphotic deformity can also be corrected by this approach which is a contraindication for posterior approach. No postoperative axial neck pain. But duration of surgery and blood loss are more. Chance of dural tear is high which can be avoided by using floating technique in excising the OPLL.

1924

P162: Surgical Results of Anterior Cervical Discectomy and Fusion Using 3D-Printed Porous Titanium Alloy Cage

Shigeharu Fukao ¹

¹ Kyoto Okamoto Memorial Hospital, Neurosurgery, Kuse-gun, Japan

Introduction: Porous titanium alloy (PTA) cage by 3D printing was developed as a material for anterior cervical discectomy and fusion (ACDF). Bone in growth is expected to promote early bone formation. In this study, we investigated the outcome of ACDF using PTA cages. Material and Methods: PTA cages (Tritanium C Anterior Cervical Cage, stryker) were introduced in 9 cases of ACDF for cervical spine degenerative disease. The average age was 54 years (44-83 years). 6 months of radiological and clinical evaluations were performed. Results: Neurosurgical Cervical Spine Scale showed an average of 10.1 before surgery and an average of 12.3 after surgery. The average fixed vertebral body height was 35.1 mm before surgery, 36.3 mm one week after surgery, and 35.0 mm 3 months after surgery. The local lordosis angle was 6.3 degrees before surgery, 7.3 degrees one week after surgery, and 6.7 degrees three months after surgery. Cage subsidence of 3 mm or more was only in one intervertebral disc (10%). 3 months after the operation, bone fusion at 9 vertebrae (90%) was confirmed. Bone fusion was confirmed in all cases 6 months after surgery. Conclusion: The PTA cage showed the low occurrence of cage subsidence and a good radiological results. It was suggested that the initial fixation of the cage was improved by giving titanium alloy a porous structure, and that it became more useful as an intervertebral bone fusion material.

1929

P163: An Unusual Cause of Dysphagia

Khalil Habboubi ¹ , Hassen Makhlouf ¹ , Meddeb Mehdi ¹ , Mzid Ahmed ¹ , Lanouar Bouzid ¹ , and Mondher Mestiri ¹

¹ Kassab Institute, Tunis, Tunisia

Introduction: Dysphagia is a common reason to consult in gastroenterology and otolaryngology. An anterior cervical osteophyte can cause mechanical compression of the pharyngo-oesophageal segment leading to this symptom. Anterior cervical osteophyte can occur in degeneration of the cervical spine, ankylosing spondylitis or in diffuse idiopathic skeletal hyperostosis (DISH), also known as Forestier’s disease. Apart from pharyngo-oesophageal segment, cervical osteophytes can cause compression of vital structures like jugular foramen, sympathetic chain, vertebral artery and trachea. Here, we present three cases of dysphagia requiring surgical intervention in our orthopedic department. Cases Presentation: Three male patients presenting with anterior osteophytes causing progressive dysphagia were treated at our institute. The average age was 64.6 years (63, 64 and 67 years). They presented with the chief complaint of progressive dysphagia for over 6 months.All patients complained about increasing dysphagia for solids worse than for liquids. One patient had severe loss of weight (10 kg in 6 months). There was no history of odynophagia, breathlessness, noisy breathing or change in voice. All patients have consulted other specialists before us. Radiographs of the cervical spine showed anterior osteophytes at different cervical levels (from C2 to C7 in one case and arising from the C4, C5, and C6 vertebra in the two other cases). Barium swallow was performed to all patients showing indentations on the posterior wall of the esophagus, confirming the extrinsic mechanical compression. They underwent an anterior cervical osteophytectomy with no need for discectomy, fusion or internal fixation. All patients reported significant improvement of dysphagia immediately postoperatively and complete resolution of symptoms within one month of follow-up. The mean follow-up of patients was an average of 28 months, and no recurrence or instability was observed in patients during this follow-up period. Conclusion: Dysphagia, airway obstruction, or both resulting from anterior osteophytes are rare. Fortunately, the diagnosis is confirmed by a simple lateral radiographs of the neck. Treatment is removal of the osteophytes, usually with no need of stabilization of the spine.

1931

P164: Cervical Spondylolysis Over Osteopetrotic Spine

Khalil Habboubi ¹ , Hassen Makhlouf ¹ , Oussema Abdelhedi ¹ , Maatoug Mahdi ¹ , Lanouar Bouzid ¹ , and Mondher Mestiri ¹

¹ Kassab Institute, Tunis, Tunisia

Introduction: Spondylolysis in the cervical spine is a rare condition. Only few cases were reported in the literature. Its association with osteopetrosis has been described by some authors but remains exceptional; it is most often indicative of the disease. We presented the case of a cervical spondylosis in a patient with osteopetrosis. Observation: We reported the case of a 20 years-old woman, followed for a left femur stress fracture on osteopetrosis treated conservatively, which consults for bilateral cervicobrachial Neuralgia following accidental hyperextension of the cervical spine. The clinical examination found a paravertebral muscular contracture, associated with painful upper cervical spines spinous processes on palpation. Neurological examination was normal. Radiological assessment by AP and lateral X-rays and a CT scan showed a C2 spondylolysis.In the absence of signs of instability on dynamic X-rays, the patient was treated conservatively. At a 2 years follow-up, there was no signs of cervical instability with the persistence of an intermittent neck pain. Discussion: Spondylolysis with or without spondylolisthesis is rare in the cervical spine. It was reported for the first time by Perlman in 1951 which was described as a defect of the pars interarticularis, in the junction between the upper and lower articular processes. The presence of these lesions in patients suffering from osteopetrosis was recognized by Suzuki and Szapanos since the eighty’s. The cause of this spondylolysis remains controversial with congenital theory based on the association of embryonic developmental abnormalities in these newborns; however autopsies of patients did not reveal spondylolysis. Only a dozen cases have been reported in the literature. In a series of seven patients published in 1998 by martin only two had a cervical spondylolysis and a case reported a multiple locations spondylolysis. Clinically, the lesion is usually asymptomatic It’s found incidentally on cervical X-rays after a benign trauma. Treatment can be sufficient with a cervical collar but this treatment can be considered only if there are no signs of instability on dynamic X-rays of the cervical spine, as in our case. A case of posterior C1-C4 fusion has been reported in the series of Martin but with an evolution towards nonunion after a 2 years follow-up. Conclusion: Osteopetrosis should be recognized as a cause of pathological spondylosis that may affect the cervical or lumbar spine, especially in children. Orthopedic treatment represent a successful option when there is no signs of instability associated.

Degenerative Lumbar

10

P165: Clinical Results of Laminectomy vs Hemilaminectomy and Arthrodesis in Degenerative Lumbar Spinal Stenosis in ISSEMYM Ecatepec Medical Center

Diana Gabriela Fourlong Galvan ¹ , Miguel Angel Fuentes Rivera ¹ , Carlos Fernando Luna de Alva ¹ , Amado Gonzalez Moga ¹ , Hugo Santos Benitez ² , Iris Sotelo ¹ , Juan Enrique Guzmán Carranza ¹ , and Gabriel Huerta Hernández ¹

¹ Centro Medico ISSEMYM Ecatepec, Traumatology and Orthopedics, Ecatepec de Morelos, Méx., México, Mexico

² Hospital Ruber, Neurosurgery, Madrid, Spain, Spain

Introduction: Degenerative lumbar spinal stenosis (DLSS) is the most common type of lumbar stenosis and increasingly being diagnosed in elderly with an approximate incidence of 5% in public Neurovascular structures compressed by the lumbar canal include: such as disc herniation, facet hypertrophy, bulging of the annulus, spondylolistesis, and thickening of the ligamentum flavum. Patients with lumbar spinal stenosis typically present with low back pain and leg pain, which occur especially when they are walking. DLSS remains the most common indication for lumbar surgery in patients over 65 years old. Objective. The aim of the present study was to analyze outcome, with respect to functional disability, pain, of patients treated with laminectomy vs hemilaminectomy and arthrodesis alone, in low back pain with or without spondylolisthesis. Material and methods. The study included 36 patients in which who had lumbar spinal stenosis, with or without spondylolistesis, divided into 2 groups (A and B), Group A included 18 patients and was treated by laminectomy while group B included 18 patients and was treated by hemilaminectomy and arthrodesis. Patients were followed for a period of one year at the ISSEMYM Ecatepec Medical Center. Follow-up was performed clinically using the Oswestry Disability Index (ODI). Results The overall evaluation of the Oswestry scale had a preoperative average for group 1 of 49.3 (±19.2) points, while for group 2 it was 54.4 (±11.1) points. This difference was not significant (P > .05). In the postoperative period, the average in group 1 was 23.4 (±14.4) points, while group 2 was 24.4 (±8.4) points. Similarly, this difference was not statistically significant (P > .05). However, the differences were insignificant between the pre- and post-surgical of both groups, although significantly greater for group 2 (P <0.001 and P < .0001 for groups 1 and 2, respectively). Conclusion. Although there were no statistically significant differences related to pain and disability among patients treated with laminectomy versus hemilaminectomy and arthrodesis, we found that lumbar laminectomy plus fusion was associated with mild clinical improvement. Therefore, our study suggests that it is important to monitor them in a period of 5 and 10 years to evaluate the postoperative evolution thus obtaining better statistical results.

12

P166: Clinicoradiological Outcome Analysis of Long Segment Decompression with Limited Spinal Fusion for Degenerative Disease of Lumbar Spine

Suman Dhar ¹ , Aditya Kashikar ¹ , Nishant Kumar ¹ , Premik B. Nagad ¹ , and Shekhar Y. Bhojraj ¹

¹ Lilavati hospital & research centre, Mumbai, India

Introduction: Degenerative lumbar spine disease (DLSD) includes spondylotic and degenerative disc disease (DDD) of lumbar spine with or without neural compression or spinal instability. DLSD is a common issue, especially in aging population resulting from "natural" wear and tear of the osseous and ligamentous structures. It presents as axial spinal pain with correlating symptoms depending on the level of spinal segments involved, degree of neural compression and its rate of development. Management & prognosis of DLSD varies with respect to underlying diagnosis, surgical decompression techniques with length of fusion and psychosocioeconomic factors. Aim: To assess clinicoradiological outcome, fusion, adjacent segment disease (ASD) following posterior fixation with posterolateral fusion (PLF) at limited segments with long segment decompression (LSD) in DSLD, with analysis of comorbidity, duration of surgery, blood loss & complications. Materials & methods: We present a retrospective analysis of 47 patients who underwent long segment decompression (at 3 or more levels) with limited fusion from Jan 2008 to Dec 2016 followed up over a period of 2 years. Inclusion criterias are spinal canal stenosis with or without disc prolapse, degenerative & lytic listhesis. Exclusion criterias include infective spondylodiscitis, redo spine surgery, malignancy, single level extruded intervertebral disc polapse without DSLD, traumatic lesions & seronegative spondyloarthopathies. All patients underwent conventional spine surgery as limited lumbar spine fusion (LLSF) with posterior fixation & PLF & multilevel lumbar decompression were done. Clinical outcomes were based on functional evaluation using modified oswestry disability index (mODI) and visual analogue score (VAS). Radiological evaluations included preoperative radiographs and MRI & post-op radiographs. Results: Study size consisted of 47 patients (9 male, 38 female), mean age 61.6, co-morbidities classified as per Charlson comorbidity index. Among them, 34 had preexisting segmental listhesis/instability. The mean levels of decompression were 3 (2.72) and fusion was 1 (1.32). The mean duration of surgery was 135.5 minutes & mean blood loss was 368 millilitres. 3 patients had iatrogenic dural injury, none had early/postop complications. Post surgery radiographic ASD (without any clinical symptoms) occurred in 15 patients (31.9%), clinical ASD in 10 patients (21.27%), 6 patients (12.77%) showed increase in listhesis (Meyerding grading) of which 4(8.51%) had only back pain complaints. The patients with increase in listhesis were managed conservatively. The preoperative mean VAS back pain (VB) was 4.74, mean VAS of leg pain (VL) was 6.98 as compared to that of postoperative VB was 1.32, VL was 2.1 & pre op mean mODI was 68.68% that of post-op mODI 11.28%. All patients were followed up for 2 years. The P value was statistically significant in VL & mODI values. Conclusion: LLSF with thorough decompression is a good treatment option for DLSD. However, LLSF preserves only limited motion and may cause stress on the adjacent levels.ASD may be closely monitored for long term outcome.

37

P167: Clinical and Radiological Outcomes of the Transforaminal Lumbar Inter Body Fusion in Low Grade Degenerative Spondylolisthesis

Ghanshyam Kakadiya ¹ and Prashant Gedam ¹

¹ Topiwla National Medical College & Nair Hospital, Orthopaedics, Mumbai, India

Introduction: Lumbar interbody fusion is a recognized surgical technique in the treatment of chronic low back pain in spondylolisthesis. Various fusion techniques have been developed using different approaches, vertebral fixation, and fusion materials. TLIF is a one of the most efficient options to surgically treat spondylolisthesis. The study aim was to evaluate the clinical, functional and radiographic outcomes of transforaminal lumbar interbody fusion (TLIF) in degenerative low-grade spondylolisthesis. Material and Methods: A prospective observational study of 120 consecutive patients (M:F = 24:96) with spondylolisthesis operated with TLIF. Clinical and functional outcome was assessed on Visual Analog Scale (VAS) and Oswestry Disability Index (ODI). The radiological outcome was assessed on sagittal alignment at a specific level, radiologic bony fusion/non-union, intervertebral disc heights and percentage of a slip in relation to the endplate. Clinical and radiological data were collected and analysed. Results: The mean age was 50.97 years. The average follow-up was 14.5 months (12-18 months). Mean preoperative ODI was 38.73 and postoperatively 21.30. Analysing the radiological fusion with clinical scores, poorer radiological fusion grades correlated with higher VAS scores for pain. 70% of patients achieved >50% reduction in pain and 60% achieved >30% reduction in ODI. Pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS) and lumbar lordosis (LL) were significantly greater in spondylolisthesis. PI, PT, and SS did not change statistically from the baseline postoperatively but increased LL and Segmental LL (P < .001). The results of our study showed a close relation between satisfactory clinical outcome (90%) and solid fusion (80%). There was however a significant number of patients with instrument failure that was found in association with fusion failure. There were no intraoperative complications. Conclusion: TLIF is an effective option to achieve circumferential fusion without severe complications. An increased pelvic incidence may be an important factor predisposing to progression in developmental spondylolisthesis. TLIF increases global and segmental LL and provides a satisfactory outcome in symptomatic low-grade degenerative spondylolisthesis.

38

P168: Spinopelvic Sagittal Malalignment and Persistence Spinal Symptoms After Transforaminal Lumber Interbody Fusion in Lumbar Degenerative Spongylolisthesis

Ghanshyam Kakadiya ¹ , Viraj Gandbhir ¹ , and Prashant Gedam ¹

¹ Topiwla National Medical College & Nair Hospital, Orthopaedics, Mumbai, India

Introduction: The ignorance of spinal sagittal alignment may potentially lead to inferior clinical results in treatment, and hence, it should always be assessed and restored. The main concept is that normal sagittal alignment helps individuals remain in a stable posture with less energy consumption. The fused spine of a locked position may cause a loss of lumbar lordosis, a forward shift of the upper trunk and subsequent adjacent degeneration. The study aim was to investigate the change of spinopelvic sagittal parameters and clinical outcomes after Transforaminal lumbar interbody fusion (TLIF) in patients with lumbar degenerative disc disease. Material and Methods: 60-consecutive patients with LDD operated with conventional TLIF were enrolled. All patients were divided into two groups according to their symptoms. Group-A symptomatic patients and Group-B asymptomatic patients. The chief complaint was a pain. Clinical and radiological data were collected and analysed. We used surgimap software to calculate sagittal spinopelvic parameters including LL, SL, SS, PI and PT. Preoperative and postoperative data recorded. Clinical and functional outcome was assessed on VAS and ODI. Spinopelvic parameters and functional outcomes compared between these groups. Results: The mean age was 65.62 ± 5.84 years in the symptomatic group and 64.97 ± 5.80 years in the asymptomatic group. There was no significant difference in clinical and operative characteristics. ODI had improvement significantly postoperatively in both the groups. A SS and SVA offset did not show any significant difference. The mean PT in the asymptomatic group was 16.1 ± 5.4 which was significantly lower than symptomatic patients 19.1 ± 5.2. The mean PI in the asymptomatic patients was 49.0 ± 8.7 which was lower than symptomatic patients (51.0 ± 9.4). The mean LL measured in the symptomatic group was 42.2 ± 9.6 which was significantly lower than asymptomatic patients (44.0 ± 11.0). Conclusion The spinopelvic parameters are directly correlated with postoperative outcomes. Poor surgical planning is likely to lead to mal-correction of spinal alignment. TLIF restores PT, global and segmental LL and provides a satisfactory outcome in symptomatic LDD. Insufficient restoration of PT was an independent factor for symptoms.

41

P169: Clinical Results and Lumbar Lordosis in High Grade Degenerative Disc Disease Treated with Unilateral and Oblique PLIF at One Level

Luigi Balla ¹ , Nicola Bellon ¹ , Fabio Vincenzo Delle Donne ¹ , Michele De Cicco ¹ , and Massimiliano Rossi ¹

¹ Madre Teresa di Calcutta Hospital, Orthopedics and Traumatology, Monselice (Padova), Italy

Introduction: Surgical treatment of lumbar degenerative disc disease (DDD) has evolved over the last two decades; in the last years the most widely used techniques in single-level pathologies involve instrumented circumferential arthrodeses with pedicle screws and intersomatic cages with different access (posterior PLIF, transforaminal TLIF, anterior ALIF, oblique OLIF or POLIF). However, it has long been known how important it is to obtain the restoration of disc height and the recovery of segmental lordosis, to avoid creation or worsening of a lumbar hypolordosis, which is considered one of the main causes of late failure. There are several retrospective studies in literature, but there is lack of those with clinical and radiographical comparison in homogeneous groups by level and pathology. Material and Methods: We selected 20 patients, treated between 2013 and 2017 with single-level unilateral oblique PLIF, with different types of cages (mainly tantalum and porous titanium). There were 12 men and 8 women, aged between 26 and 50 years, suffering from high grade degenerative disc disease (Pfirrmann 4-5) and divided into two groups of 10, depending on the level of operated pathology (L4-L5 and L5-S1). They complained of low back pain or chronic lumbosciatalgia, not resolved by other treatments. Preoperatively, ODI (Oswestry disability index), lumbar pain (VAS back pain), lower limb pain (VAS leg pain) were evaluated, and the angle of lumbar lordosis between L2 and S1 (superior plate) was measured with radiograms in orthostatism. Clinical and radiographic follow-up for disability, pain and lumbar lordosis is 2 years for all patients. Results: After 2 years, clinical results were good and excellent in 100% of cases. Both ODI and VAS back pain and VAS leg pain were reduced by more than 70%, compared to preoperative values. The mean value of total angle of lumbar lordosis (L2-S1) was 45.3°, compared to a preoperative mean value of 43.4°, with an increase of 4.2% for the two groups of patients. The increase in lumbar lordosis was greater in the L5-S1 group (preoperative mean 43.3° and postoperative 45.6°) than in the L4-L5 group (preoperative mean 43.5° and postoperative 45.0°). Conclusion: Surgical treatment of severe lumbar degenerative disc disease (DDD) with instrumented circumferential arthrodesis must guarantee an immediate stability of the implant, such as to favor a valid intervertebral fusion. For a better clinical result and to reduce any late complication (lack of interbody fusion, cage mobilization, degeneration of adjacent segment), it is important to restore the disc height and segmental lordosis, without creating or favoring lumbar hypolordosis. This objective is a must in presence of initial disc degeneration at adjacent levels to the treated one, in patients over 60 years of age and in patients with moderate sagittal imbalance. In younger patients, with the absence of adjacent disc degenerative pathologies and with preoperative values of moderate lumbar hypolordosis, the increase in postoperative lumbar lordosis seems to be a factor of minor importance for a good clinical outcome.

42

P170: Fenestrated Pedicle Screws and Augmentation with Polymethylmethacrylate in Lumbar Osteoporotic Degenerative Surgery

Luigi Balla ¹ , Nicola Bellon ¹ , Fabio Vincenzo Delle Donne ¹ , Michele De Cicco ¹ , and Massimiliano Rossi ¹

¹ Madre Teresa di Calcutta Hospital, Orthopedics and Traumatology, Monselice (Padua), Italy

Introduction: In recent years the average age of patients undergoing surgical treatment for degenerative lumbar diseases has increased. The main cause of implant failure was the early mobilization of pedicle screws, favored by osteoporosis. Therefore fenestrated screws were used for injection of polymethylmethacrylate (PMMA), both in revision surgery and in first implants. The main complications of this technique are pulmonary embolism and the leakage of cement from vertebral bodies. Several studies have analyzed the percentage of these complications and their incidence about the appearance of symptomatic events, with the indications to prevent or reduce them. Material and Methods: Between 2016 and 2018 we treated 22 patients aged between 64 and 85 years (14 women and 8 men), of lumbar instrumented arthrodesis for degenerative diseases in osteoporosis. In 14 cases these were the first implants, in 8 revisions. We used fenestrated screws and augmentation with high viscosity polymethylmethacrylate (PMMA), for a maximum of 10 screws and not injecting more than 40 gr of powder for each patient. Clinical controls, hospitalization and after discharge, were aimed at highlighting symptomatic patterns suspected for pulmonary embolism or secondary to cement dispersion. In postoperative x-rays we verified the leakage of cement outside vertebral bodies, while in those at a distance we looked for signs of loosening of the pedicle screws. Clinical and radiological follow-up was at least 1 year for all patients. Results: We had no symptomatic cases of pulmonary embolism during surgery or in the immediate postoperative period. In a man undergoing revision surgery, who was obese, cardiopathic and diabetic, dyspnoea occurred after discharge, diagnosed and treated as heart failure, without the need to perform pulmonary angiography. In 17 cases (77%) we verified a cement dispersion, which was symptomatic only in 2 cases (1 inside the lumbar canal and 1 outside, both with tolerated dysesthesias). After 1 year there was no case of mobilization of the screws. Conclusion: The introduction of fenestrated pedicle screws for the insertion of cement into vertebral bodies, has greatly reduced the incidence of failures caused by the mobilization of the screws in degenerative osteoporotic lumbar surgery. Moreover, this technique can cause complications such as pulmonary embolism and the leakage of polymethylmethacrylate (PMMA) outside vertebral bodies. Both are almost always asymptomatic but should not be underestimated. Careful anesthetic monitoring during the cementing phase and use of high viscosity cement in a non-excessive quantity injected at low pressure, are crucial to reduce the risk of major events. The greater dispersions of polymethylmethacrylate (PMMA) occur in revision surgery and involve greater risk of complications, as well as being able to cause a worse grip of the screws to the bone. In our opinion, with the exception of preoperative cardiological contraindications, the use of fenestrated screws with cement is a first choice indication in osteoporotic lumbar degenerative surgery.

122

P171: Lumbar Fusion Surgery for Patients with Back Pain and Degenerative Disc Disease: An Observational Study from the Canadian Spine Outcomes and Research Network

Nathan Evaniew ¹ , Ganesh Swamy ¹ , Bradley Jacobs ¹ , Jacques Bouchard ¹ , Roger Cho ¹ , Neil Manson ² , Raja Rampersaud ³ , Jerome Paquet ⁴ , Chris Bailey ⁵ , Michael Johnson ⁶ , Najmedden Attabib ² , Charles Fisher ⁷ , Greg McIntosh ⁸ , and Ken Thomas ¹

¹ University of Calgary, Calgary, Canada

² Canada East Spine Centre, St. John NB, Canada

³ University of Toronto, Toronto, Canada

⁴ Université Laval, Québec, Canada

⁵ Western University, London, Canada

⁶ University of Manitoba, Winnipeg, Canada

⁷ University of British Columbia, Vancouver, Canada

⁸ CSORN, Markdale, Canada

Background: Surgery for patients with back pain and degenerative disc disease is controversial, and studies to date have yielded conflicting results. Purpose: In order to optimally inform shared clinical decision-making, we evaluated the effects of lumbar fusion surgery for patients with back pain and degenerative disc disease from the Canadian Spine Outcomes and Research Network (CSORN). Study design/setting: We performed an uncontrolled retrospective observational study using data that were prospectively collected from consecutive patients enrolled in the CSORN registry at 11 centers between 2015 and 2019. Patient sample: We included patients with primary symptoms of low back pain and a diagnosis of degenerative disc disease. We excluded patients with primary symptoms of claudication or radiculopathy, and diagnoses other than degenerative disc disease such as stenosis, spondylolisthesis and deformity. Outcome Measures: Our primary outcome was change in patient-reported back pain at 12 months of follow-up, and our secondary outcomes were satisfaction, disability, health-related quality of life, and rates of adverse events. Methods: We implemented Minimum Clinically Important Differences (MCIDs) to interpret treatment effects, collected adverse events with the Spinal Adverse Events Severity System (SAVES), and tested for specific associations using multiple binomial logistic regression. Results: We included 84 patients (which represent 2% of the registry) that were treated with a variety of anterior or posterior techniques. At 12 months of follow-up, we observed a statistically significant improvement of back pain that exceeded the threshold of MCID (mean change −3.7 points, SD 2.6, P < .001, MCID = 1.2). Further, 77% experienced individual improvements equal or greater than the MCID, and 81% reported being “somewhat” (35%) or “extremely” (46%) satisfied. Patients also experienced statistically significant improvement of Oswestry Disability Index (−17.3, SD 16.6) and Short Form-12 Physical Component Summary (10.3, SD 9.6) and Mental Component Summary (3.1, SD 8.3); all P < .001). In adjusted analyses, we failed to observe significant associations with specific patient characteristics or surgical techniques except that those with worse pre-operative pain were more likely to achieve MCID. Two patients required reoperation during their index admission, but adverse events were otherwise uncommon. Conclusions: Among a highly selective group of patients undergoing lumbar fusion surgery for degenerative disc disease, most experienced a clinically significant improvement of back pain as well as significant improvements of disability and health-related quality of life, with high satisfaction and low rates of adverse events within one year of follow-up. These findings suggest that surgery for this indication may provide some benefit. Caution and further research are warranted when considering application to clinical practice.

146

P172: Clinical Implications of Lumbar Developmental Spinal Stenosis—Back Pain, Radicular Leg Pain and Disability with 2206 Subjects

Marcus Kin Long Lai ¹ , Prudence Wing Hang Cheung ¹ , Dino Samartzis ² , Jaro Karppinen ³ , Kenneth Man Chee Cheung ¹ , and Jason Cheung ¹

¹ University of Hong Kong, Orthopaedics and Traumatology, Hong Kong, Hong Kong

² Rush University Medical Center, Orthopedic Surgery, Chicago, USA

³ Oulu University Hospital and University of Oulu, Oulu, Finland

Introduction: Low back pain (LBP) and radiating leg pain are two common health problems around the world. Lumbar developmental spinal stenosis (DSS) may play an important role in pain generation. It is described as pre-existing narrowed vertebral canals at multiple lumbar levels with earlier onset of neurological compromise. Therefore, this study was designed to assess the interaction of DSS and different radiological phenotypes in producing LBP, radiating leg pain and disability. Material and Methods: This was a prospective cohort of 2206 Chinese subjects with clinical assessments and matched L1-S1 axial and sagittal MRI. Information related to LBP and radiating leg pain by VAS was recorded by age of onset, any pain experienced in the past month (30 days) and year (365 days). Demographics including age, gender, height, weight and body mass index (BMI), smoking habit, exercise and occupation were obtained and calculated. ODI, SF-36 and Roland-Morris Disability Questionnaire were obtained. Two independent investigators with excellent interobserver and intraobserver reliability measured the axial anteroposterior (AP) vertebral canal diameter, facet joint angulation and tropism, any disc herniation, Pfirrmann grading, endplate irregularity, high intensity zone, radial tear, spondylolisthesis, Modic change and anterior marrow change. DSS was classified as axial AP vertebral canal diameters below the cut-offs at 3 or more levels: L1 < 19 mm, L2 < 19 mm, L3 < 18 mm, L4 < 18 mm, L5 < 18 mm, S1 < 16 mm. Presence of DSS or not was used to dichotomize subjects and multivariate logistic regression models studied the four clinical outcomes of LBP and radiating leg pain in the past month and year. Results: Of the 2206 subjects, 153 had DSS. Mean age was 51.9 years with mean BMI of 23.7. There were 38.4% males and 61.6% females. 72.1% subjects had LBP in the past year and 56.7% had LBP in the past month. 41.0% subjects had radicular leg pain in the past year and 30.5% had radicular leg pain in the past month. DSS subjects had worse LBP and higher incidence of radiating leg pain in the past month and year, and worse outcome scores, higher disc herniation and degeneration score. No significant associations were observed between disc degeneration and herniation, facet joint morphology, high intensity zones, and Modic changes with LBP and leg pain. For LBP, spondylolisthesis was found as significant risk factors for our model. Subjects with spondylolisthesis had 1.526 (95% CI = 1.004-2.322; P = .048) times higher odds of LBP in the past month and 1.762 (95% CI = 1.047-2.963; P = .033) times higher odds of LBP in the past year. After adjusting for gender, age, BMI and workload, our model found that subjects with DSS had higher odds of radiating leg pain in the past month (adjusted OR = 1.439; 95% CI = 1.004-2.063; P = .048) and past year (adjusted OR=1.811; 95% CI = 1.262-2.600; P = .001). Conclusion: Based on this large-scale prospective cohort, we identified risk factors for acute and chronic LBP and radiating leg pain. Spondylolisthesis is a main risk factor for both acute and chronic LBP, while subjects with DSS and SNs had higher risks of acute and chronic radiating leg pain. The impact of our findings relates to prognostication and management outcomes.

213

P173: Comparison of the Morphology Change of Adjacent Disc After Anterior and Oblique Lumbar Interbody Fusion

Fang-Wei Hsu ^1,2 , Kun-Hui Chen ¹ , Chien-Chou Pan ¹ , Ning-Chien Chin ¹ , Cheng-Min Shih ¹ , Yun-Che Wu ¹ , Kuan Kai Tung ¹ , and Cheng-Hung Lee ¹

¹ Taichung Veterans General Hospital, Taichung, Taiwan, Department of Orthopedic, Taichung, Taiwan

² Department of Orthopedic, Kuang Tien General Hospital, Taichung, Taiwan

Introduction: Spondylolisthesis and degenerative disc disorder in adults are the most common indications of lumbar surgery. Solid fusion may influence the adjacent segment stresses and affect the degeneration rate. The lordotic angle of anterior (ALIF) and oblique lumbar interbody fusion (OLIF) cages has been reported with the ability to restore the index lumbar lordosis, which prevented the adjacent segment from degeneration. The purpose of this study was to compare morphology changes of adjacent disc in patients who received the anterior and oblique lumbar interbody fusion. Material and Methods: We retrospectively reviewed 47 patients who received ALIF or OLIF for lumbar degenerative disease. The radiologic measurement of index lordosis, adjacent disc angle, anterior and posterior adjacent disc height were performed at pre-operative, 1-month, and 1-year post-operatively. Clinical outcomes were evaluated by European Quality of life scale (EQ-5D), total Visual Analog Scale of pain in total (VASP-total), in back (VASP-back), and Oswestry Disability Index (ODI). Results: All 47 patients (48.9% ALIF) demonstrated significant increase in index lordosis and improvement of clinical symptoms after 1-year follow up. The anterior and posterior disc height of adjacent disc showed significant decrease at post-operative 1-month and 1-year without progression during follow-up. In the ALIF group, index lordosis showed significant increase after post-op one year accompanied with decrease in anterior disc height of the adjacent disc. In the OLIF group, both anterior and posterior adjacent disc height were significantly decreased after year follow up. Increased in index lordosis without significance was observed. Both groups showed no significant change in adjacent disc angle after surgery. Discussion: Without restoration of the lordotic angle, the adjacent segment degeneration and flat back deformity may develop after spinal deformity correction. According to previous reports, both ALIF and OLIF were able to restore the lordotic angle at index level due to their design of cage angle. Our result revealed an increase of the index lordosis whilst the adjacent disc angle remained unchanged. Although the adjacent disc heights were decreased after ALIF and OLIF surgery, no progressive decreasing was noted after one year follow-up. Additionally, index lordosis change was greater in ALIF compared to OLIF. Anterior longitudinal ligament (ALL) was released in ALIF surgery which may result in an increase in anterior disc height at index level. However, lack of release in ALL led to high index level pressure and resulted in cage subsidence and failure of restoration of index lordosis after OLIF. Conclusion: In our study, the anterior disc height of adjacent disc significantly decreased whilst no difference in adjacent disc angle after ALIF/OLIF surgery. However, the fact that index lordosis increased after ALIF surgery and posterior disc height of adjacent disc was decreased in only OLIF surgery may be related to the different operation strategy toward ALL release. We suggest that ALIF surgery is able to restore sufficient lumbar lordosis and prevent the adjacent disc height from decreasing and compensating shape change. OLIF surgery prevents the adjacent disc angle change from compensation, but the disc height cannot be preserved after surgery.

275

P174: Post Operative Lumbar Paraspinal Atrophy: Does the Approach Matter?

Alfredo Guiroy ¹ , Federico Landriel ² , Carlos Zanardi ³ , Federico Fernandez Molina ⁴ , Martin Gagliardi ¹ , Ruben Morales Ciancio ¹ , Santiago Hem ² , and Nelson Picard ³

¹ Spanish Hospital, Orthopedics, Mendoza, Argentina

² Hospital Italiano, Neurosurgery, Buenos Aires, Argentina

³ Clinica La Pequeña Familia, Neurosurgery, Junin, Argentina

⁴ INECOD, Neurosurgery, La Plata, Argentina

Introduction: The aim is to compare the level of post-op muscle atrophy related to the different approaches used in segmental lumbar fusion for degenerative disease (midline vs Wiltse vs MIS TLIF). Materials and Methods: An observational, cross sectional, multicenter, descriptive and retrospective study was performed including a series of patients undergoing surgery for lumbar degenerative disease. We analyzed 45 patients (24 females), with a mean age of 58.7 years, undergoing surgery in 5 surgical center between 2015 and 2018. A one-level instrumented fusion, from L3 to S1 was performed (7 cases L3-L4, 25 cases L4-L5 and 13 cases L5-S1). In 15 cases a midline approach was used; in 15 a Wiltse approach was used and in 15 cases a MIS TLIF approach was used. All the patients were studied preoperatively and for at least 6 months after surgery (mean follow up 14.6 months) with magnetic resonance imaging. The images were analyzed by three specialists in spine surgery. Two variables were considered to compare the level of atrophy before and after surgery: cross sectional area (CSA) of the multifidus muscle (MM) and spinal erector muscles (SEM) and the fat infiltration level (FI) using the Kjaer visual classification. The analyses were conducted using the RStudio (1.1.383 version) statistical software, and the p values obtained were compared using the Wilcoxon rank sum test. Results: No significant differences were found between the approaches in terms of MM atrophy. The comparison of p for CSA and the SEM evidenced differences between MIS TLIF vs midline (p .018) and midline vs Wiltse (p .027). Conclusion: The minimally invasive approaches used for decompression and lumbar monosegmental arthrodesis had more impact on the EMs than on the MM. Randomized controlled trials might be useful to validate the results of this investigation.

298

P175: Patients with Worse Symptoms Required Accurate Correction of Age-Adjusted Post-Operative Sagittal Parameter by Anterior Lumbar Fusion. A Retrospective Study

Kuan Kai Tung ¹ , Kun-Hui Chen ¹ , Chien-Chou Pan ¹ , Wen-Xian Lu ² , Ning-Chien Chin ¹ , Cheng-Min Shih ¹ , Yun-Che Wu ¹ , Fang-Wei Hsu ^1,3 , and Cheng-Hung Lee ¹

¹ Taichung Veterans General Hospital, Taichung, Taiwan, Department of Orthopedic, Taichung, Taiwan

² Department of Orthopedic, Feng Yuan Hospital Ministry of Health and Welfare, Taichung, Taiwan

³ Department of Orthopedic, Kuang Tien General hospital, Taichung, Taiwan

Introduction: Recent studies have suggested three sagittal profiles: (1) sagittal vertical axis (SVA), (2) pelvic tilt (PT), (3) and pelvic incidence minus lumbar lordosis (PI-LL) may be age dependent. The clinical applications of the age-adjusted parameters remain inconclusive. This study aims to investigate whether patients with worse symptoms required meticulous correction in order to achieve age-adjusted postoperative sagittal profile by anterior lumbar fusion technique. Material and Methods: 50 patients receiving anterior lumbar fusion treatment for adult spinal degenerative deformities, including Anterior (ALIF) and Oblique (OLIF) interbody fusion. Severity of symptoms were measured via health-related quality of life (HRQOL) score including European Quality of life scale (EQ5D), Oswestry Disability Index (ODI), Visual Analog Scale of Pain calculated in total (VASP-Total), back (VASP-Back), and the more severe leg (VASP-Legs). Patients were stratified by the severity cut-off value of each HRQOL score before the operation. After the operation, patients were divided into “Sufficient group” and “Insufficient group” in accordance with the achievement or under treatment of three age-adjusted parameters: SVA, PT, and PI-LL. Postoperative clinical outcomes were measured and compared to preoperative baseline between groups at 1-year follow-up. Following that step, correlation between optimal parameters of major sagittal profiles and the HRQOL were analyzed. Results: Postoperative parameters of the population (mean 59.5 y old, 58% female, 60% ALIF) were: SVA = 32.5 ± 35 mm, PT = 18.8° ± 9.2°, and PI-LL = 8.3° ± 14.8°. All three parameters and HRQOLs showed significant improvement after anterior lumbar fusion. In the initial step of the study, 68-78% of the patients suffered from worse symptoms in HRQOLs. Sufficient correction of age-adjusted SVA, PT, and PI-LL showed statistically better outcome in EQ-5D, ODI, VASP in total, and back among patients with worse symptoms compared to insufficient correction. However, no difference of HRQOLs was observed in the patients with milder symptoms after correction regardless of sufficiency. ALIF showed better outcomes in EQ-5D and VASP-Legs compared to OLIF. However, sagittal parameters showed no difference between two operation methods. According to multiple regression analysis, age-adjusted PT has the most significant impact on EQ5D and ODI. Contrarily, SVA is considered the most important factor in VASP in total, back, and legs, P < .05 for all significant results. Discussion: Our result considering under-correction of age-adjusted SVA significantly worsens the HRQOL is compatible with recent studies. However, studies have shown that not until the compensating mechanisms of PT and PI-LL was deliberated will the SVA become clinically imbalanced. In this study, we reported by sufficient correction of PT and PI-LL in patients with clinically worse symptoms, promising improvement of symptoms and disability status could be achieved. Moreover, far from SVA, which was difficult to measure intra-operatively, PT and PI-LL could be managed and manipulated during the operation. Age-adjusted threshold of the parameters should be taken into consideration of the operative planning. Conclusion: Anterior lumbar fusion technique, including ALIF and OLIF, was proven to be advantageous once sufficient correction of SVA, PT, and PI-LL was achieved in patients presented with more severe symptoms and disability status in our study.

320

P176: Gender Differences in the Surgical Management of Lumbar Degenerative Disease: A Systematic Review

Mark Maclean ¹ , Charles Touchette ² , Jae Han ¹ , Sean Christie ¹ , Gwynedd Pickett ¹

¹ Dalhousie University, Division of Neurosurgery, Halifax, Canada

² University of Sherbrooke, Division of Neurosurgery, Sherbrooke, Canada

Introduction:A paucity of literature is available to guide management of degenerative lumbar disease which stratifies on the basis of demographic factors. The objective of this study was to systematically map and synthesize the adult surgical literature regarding gender differences in pre- and post-operative patient-reported clinical assessment scores for patientswith degenerative lumbar disease (disc herniation, spondylolisthesis, spinal canal stenosis). Materials and Methods:A systematic review was performedaccording to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extension for Scoping Reviews (PRISMA-ScR) guidelines.MEDLINE, EMBASE, and Cochrane Registry of Controlled Trials were searched from inception to September 2018. Levels of Evidence were scored using the Oxford Centre for Evidence-Based Medicine grading tool.Results:Thirty articles were identified, accounting for 32,951 patients. Six studies accounted for 84% of patients; five of the six studies were published by European groups. The most common conditions were disc herniation (59.0%), disc degeneration (20.3%) and canal stenosis (15.9%). The majority of studies reported worse pre-operative pain (93.3%), disability (81.3%), and HRQoL (75%) among females. The remainder reported equivalent pre-operative scores between males and females. Eighty percent of studies found females had worse absolute post-operative scores in at least one outcome category. The remainder reported equivalent absolute post-operative scores between males and females. Seventy-three percent of studies reported either an equivalent or greater interval change for females. The majority of studies provide Level IV evidence. Conclusion:Female patients have an inferior clinical status (pain, disability, HRQoL) at the time of surgery for degenerative lumbar disease. However, they demonstrate an equal or greater treatment effect compared to males.

322

P177: Validation of a Quantitative Degenerative Lumbar Spondylolisthesis Instability Classification System

Mark Maclean ¹ , Ryan Greene ¹ , Charles Fisher ² , Raja Rampersaud ³ , Chris Bailey ⁴ , and Andrew Glennie ⁵

¹ Dalhousie University, Division of Neurosurgery, Halifax, Canada

² University of British Columbia, Department of Orthopedic Surgery, Vancouver, Canada

³ University of Toronto, Department of Orthopedic Surgery, Toronto, Canada

⁴ University of Western Ontario, Department of Orthopedic Surgery, London, Canada

⁵ Dalhousie University, Department of Orthopedic Surgery, Halifax, Canada

Introduction: The qualitative Degenerative Lumbar Spondylolisthesis Instability Classification (DSIC) system highlights clinical and radiographic parameters contributing to spondylolisthesis instability. Patients are classified into one of three “Types” (1: stable, 2: potentially unstable, 3: unstable). The system facilitates selection of surgical procedure based on the DSIC Type (1: decompression only, 2: decompression and posterolateral fusion, 3: transforaminal lumbar interbody fusion). The purpose of this study was to generate a quantitative version of the DSIC scoring system and objectively determine whether surgeons are applying the existing qualitative system to select optimal (recommended), more invasive, or less invasive procedures for treatment of degenerative lumbar spondylolisthesis (DLS). Materials and Methods: A cut-off threshold of “low-quality” evidence or better was applied to the qualitative DSIC system; signs of instability with “very-low” quality evidence were excluded. Remaining signs of instability were used to generate the quantitative DSIC system. Points were assigned based on low (1-point), moderate (2-points), or high-quality (3-points) literature evidence. Quantitative scores were assigned retrospectively to patients in the Canadian Spine Outcomes Research Network Registry. Scores were converted to one of three DSIC types: 0-2 points (Type 1), 3 points (Type 2), 4-5 points (Type 3). Quantitative (calculated) DSIC Types were compared to qualitative (surgeon-assigned) DSIC Types. Results were stratified by procedure. Results: The following signs of spondylolisthesis instability were included and assigned single point value: presence of facet effusion, absence of disc height loss (>6.5 mm), translation (>4 mm), kyphotic or neutral disc angle on flexion radiographs, and presence of low back pain (LBP) (>5/10 intensity). Complete data was available for 292 patients. Surgeons assigned the following DSIC Types (%): Type 1 (30.8), Type 2 (52.4), and Type 3 (16.8). Calculated DSIC Types were (%): Type 1 (57.5), Type 2 (33.9), and Type 3 (8.6). Surgeons assigned a higher DSIC Type than what was objectively calculated, in 41.4% of cases. In thirty-four percent of cases, surgeons performed a more invasive surgical procedure (corresponding to one DSIC Type higher than assigned), and in 9.2% of cases a much more invasive surgical procedure (corresponding to two DSIC Types higher than assigned). Conclusion: We present a quantitative, evidence-based scoring tool which may be used by surgeons to objectively determine the degree of spinal instability for patients with DLS. Surgeons applied the qualitative DSIC system and assigned greater instability than what was objectively determined, in 41.4% of cases. When stratifying calculated and surgeon-assigned DSIC Types by procedure offered, patients received a more invasive surgical procedure than what is recommended in 55.6 and 43.2% of cases, respectively.

340

P178: Correlation Between Clinical Scoring Systems and Quantitative MRI Parameters in Degenerative Lumbar Spinal Stenosis

Siddharth Gupta ¹ , Tungish Bansal ² , Shahrukh Khan ³ , Abhishek Kashyap ³ , Sumit Sural ³

¹ Maulana Azad Medical College, Orthopaedics, NEW DELHI, India

² All India Institute of Medical Sciences, Orthopaedics, New Delhi, India

³ Maulana Azad Medical College, Orthopaedics, New Delhi, India

Introduction: Several clinical scores and quantitative MRI parameters have been defined for diagnosis and monitoring treatment in degenerative lumbar spinal stenosis (LSS). A few studies have found some correlation while many others refute the same leading to confusion. Hence, we analysed 10 frequently used clinical scores with 8 quantitative MRI parameters to find out their correlation. Material and Methods: Eighty-two patients aged more than 40 years with clinico-radiological features suggestive of degenerative LSS were enrolled over 1.5 years. All patients completed 10 clinical questionnaires which included the Oswestry Disability Index (ODI), Swiss Spinal Stenosis Questionnair e(SSS), Quebec Pain Disability scale (QPD), Visual Analogue Scale (VAS), modified Japanese Orthopaedic Association scale(mJOA), Pain Disability Index (PDI), Short Form-36 questionnaire (SF-36), Self-paced walking test(SPWT), Euro Quality of life-VAS (EuroQol-VAS) and Neurogenic claudication outcome score (NCOS). Lumbosacral MRIs were also performed and 8 quantitative MRI parameters namely transverse and anteroposterior diameter of dural sac (TDS, APDS), anteroposterior diameter of spinal canal (APDS), ligamentous interfacet distance (LID), mid-sagittal diameter of thecal sac (MSDT), cross-sectional area dural sac (CSAD), lateral recess height and angle (LRH, LRA) were measured at the maximum stenotic level at the level of the disc. The clinical and radiological parameters were then statistically analysed and correlated. Results: The mean age was 53.02 years and included 51 females (62.2%) and 31 (37.8%) males. The NCOS had a strong positive correlation with TDS (r = .806, P = .00) and a moderate positive correlation with 4 others namely CSAD (r = .580, P = .00), LID (r = .519, P = .00), APDS (r = .326, P = .003) and APDD (r = .306, P = .005). MSDT correlated with four clinical scales with moderate negative correlation with SSS questionnaire (r = −.426, P = .00), VAS (r = -.407, P = .00), ODI(r = -.389, P = .00), and QPD(r = -.306, P = .005). LRH had moderate negative correlation with ODI (r = -.447, P = .00), Euro QOL-VAS (r = -.396, P = .00) and VAS score (r = -.315, P = .00). The LRA had a moderate negative correlation with the EuroQOL-VAS (r = -.460, P = .00) and ODI (r = -.377, P = .00). The CSAD had a moderate negative correlation with PDI (r = -.383, P = .000). Among SF-36 components, Role limitations due to emotional problems had moderate correlation with APDS (r = .326, P = .003), APDD (r = .305, P = .005) and LRA(r = -.345, P = .001). Conclusions: Various MRI parameters were compared with clinical scores and the Neurogenic Claudication Outcome Score was found to be correlating with maximum parameters as it takes care of the complete presentation of LSS specifically.

353

P179: Multilevel Lumbar Canal Stenosis: Long Term Result of Lumbar Laminoplasty is Better Than Decompressive Laminectomy

Anowarul Islam ¹

¹ Bangabandhu Sheikh Mujib Medical University, Orthopaedics, Dhaka, Bangladesh

Introduction: Abnormal narrowing of the lumbar spinal canal, lateral recess, foramen and extraforaminal space is called lumbar canal stenosis. Patients are presented with low back pain with or without radiculopathy and neurological claudication and may need surgical intervention if conservative treatment fails. Lumbar laminoplasy and decompressive laminectomy are few of the surgical intervention techniques. Material and Methods: 120 consecutive patients underwent lumbar laminoplasty and laminectomy in BSMMU and other private hospitals in Dhaka city from July(2009) to June(2019).The patients were randomized into two groups: one group for lumbar laminoplasty and another group by decomprerssive laminectomy. Clinical and functional outcome were measured by VAS, JOA and ODI score. Results: Pre-operative mean VAS score of back pain and leg pain were 7.0 ± .7 and 7.2 ± 1.1 which were significantly reduced to 1.0 ± .2 and 1.0 ± .8 in laminoplasty group where as in lamenectomy group preoperative VAS for back pain and leg pain 8.0 ± .6 and 7.5 ± 1.6 which were significantly reduced to 3.0 ± .4 and 2.0 ± .7 respectively at final follow-up. Preoperative mean JOA score was 8.6 ± 2.2 which was significantly increased to 14.8 ± .4 in laminoplasty group where as in lamenectomy group pre operative score was 8.3 ± 1.8 which was significantly increased to 12.6 ± .6 after 24 months of surgery. Pre-operative mean ODI was 34.4 ± 3.0 which was significantly reduced to 8.5 ± 2.2 in laminoplasty group where as in laminectomy group preoperative score was 32.4 ± 2.8 which was significantly reduced to 10.4 ± 3.2 after 12 months of surgery. Conclusion: Lumbar laminoplasty provides long-term pain relief and good clinical and functional outcome.

359

P180: At One Year Follow-Up There is No Difference in Patient Reported Outcomes or Radiographic Alignment in Cortical Bone Trajectory Versus Traditional Pedicle Screw Fixation in Transforaminal Lumbar Interbody Fusion

Zakariah Siyaji ¹ , Athan Zavras ¹ , Mark Berkowitz ¹ , Ali Piracha ¹ , Samuel Rudisill ¹ , Garrett Harada ¹ , Michael Nolte ¹ , Bryce Basques ¹ , and Matthew Colman ¹

¹ Rush University Medical Center, Orthopedic Surgery, Chicago, USA

Introduction:Transforaminal Lumbar Interbody Fusion (TLIF) is a common surgery used to treat instability and deformity of the lumbar spine.The traditional open approach (PS) uses pedicle screws which require extensive dissection of paraspinal tissue in order to reveal the anatomic landmarks and ensure appropriate screw trajectory. Cortical bone trajectory (CBT) screw fixation is a newer technique that requires less lateral paraspinal dissection while also demonstrating enhanced pullout strength in biomechanical studies. This is purportedly due to enhanced screw thread contact with cortical bone as a result of the medial to lateral and caudal to cephalad trajectory through which the screw traverses the pedicle. There is a paucity of literature analyzing the outcomes of cortical TLIF. The aim of this study was to provide a comparative analysis of differences in patient-reported outcomes, radiographic measures, and intraoperative characteristics between CBT and traditional PS TLIF.Methods:This study retrospectively examined patients undergoing either CBT or traditional PS TLIF by a single surgeon for degenerative low-grade spondylolisthesis from 2017 to 2020 with 6-month minimum follow-up. Patient demographics, comorbidities, postoperative complications, and patient-reported clinical outcomes (OswestryDisability Index [ODI],Visual Analog Scale [VAS]- back pain, VAS-leg pain, 12-item Short Form Survey [SF-12], Veterans RAND 12 Item Health Survey [VR-12]) were analyzed. Preoperative and postoperative radiographic parameters were assessed for differences in spinopelvic alignment and correction. Fusion rates were determined via radiographic and CT evidence. T-test and chi-square for continuous and categorical variables were performed to compare baseline characteristics. Multivariable regression controlled for baseline characteristics and assessed differences in clinical outcomes associated with the procedure methods. The threshold for statistical significance was set toP< .05.Results:A total of 29 cortical and 103 traditional open TLIF patients were assessed with mean follow-up of 12.71±9.14 and 13.31±9.35 months, respectively. While both groups reported improvement, there was no significant difference in the magnitude of improvement in ODI (P = .171), VAS-back (P = .085), VAS-leg (P = .649), SF-12 (P = .166), or VR-12 (P = .145). Radiographically, there was no significant difference in parameter improvement other than sacral slope (SS) (CBT: 11.51±6.83, PS TLIF: 6.76±5.83,P = .008). Mean operative duration was significantly shorter in the CBT TLIF group (168.1±50.7min) than the PS TLIF group (215.07±97.7min,P = .049), and these patients experienced lower estimated blood loss (126.6ml±158 vs 250.3ml±287;P = .006). The incidence of postoperative radiculitis was significantly lower in CBT (34.5%) patients compared to PS TLIF (45.6%) patients (P = .049). There were no differences observed in rates of fusion (CBT TLIF: 96.55%; PS TLIF: 94.17%;P = .189) or revision surgery (CBT TLIF: 13.8%, PS TLIF: 9.71%,P = .084).Conclusion:CBT TLIF and PS TLIF showed no significant difference between the degree of improvement in subjective patient reported outcomes nor objective radiographic metrics. However, CBT TLIF is associated with significantly less blood loss, operative time, and postoperative radiculitis than PS TLIF. These results suggest that CBT TLIF is an appropriate alternative approach to the treatment of lumbar pathologies, particularly in patients with comorbidities contributing to poor wound healing. Additional studies are needed to further describe long-term patient reported and radiographic outcomes.

367

P181: Patient Reported Outcome Analysis After Posterior Decompression and Posterolateral Fusion Surgery in Lumbar Degenerative Spondylolisthesis

Prakash Paudel ¹

¹ Nepal Mediciti Hospital, Neuroscience, Kathmandu, Nepal

Introduction: Lumbar degenerative spondylolisthesis is an acquired slippage of a vertebra due to degenerative arthritis of the facet joints without any defect in the neural arc. Degenerative spondylolisthesis is commonly treated with posterior decompression and posterolateral fusion. This study aims to evaluate the clinical outcome of posterior decompression and instrumented posterolateral fusion surgery by analysing patient reported outcome measures. Material and Methods: A retrospective analysis of prospectively collected data of patients who had undergone posterior decompression and instrumented posterolateral fusion for low grade lumbar degenerative spondylolisthesis between September 2017 and August 2019 was conducted at Nepal Mediciti Hospital Lalitpur Nepal. Patients who had follow up period of less than three months and other types of spondylolisthesis were excluded. Functional outcome was assessed by comparing pre and post-operative patient reported outcome measures: VAS leg pain, VAS back pain and Oswestry Disability Index (ODI). The paired t-test was used for statistical analysis. Results: Of the 16 patients, 81.25% were female. Mean age and mean follow up period were 59 ± 10.47 years and 13.56 ± 7.15 months respectively. Seventy five percent had grade I and 25% had grade II spondylolisthesis. Most common level of spondylolisthesis was L4/5 (62.5%). Fourteen patients reported improvement in their symptoms after surgery. The change in functional outcome score between baseline and at follow up evaluation were 32.70 ± 17.44 for ODI, 3 ± 1.89 for VAS leg pain, and 5.37 ± 2.36 for VAS back pain (P < .001). Superficial wound infection was the most common complication observed in 18.3%. Conclusion: In our cohort, 87.5% had improvement in their symptoms after surgery. The changes in mean score of all patient reported outcome measures before and after surgery were statistically significant. We recommend a larger prospective study to assess the long term outcome after posterolateral fusion surgery in degenerative spondylolisthesis.

396

P182: The Influence of Body Mass Index in Obese and Morbidly Obese Patients on Complications and 30- and 90-day Readmissions Following Lumbar Spine Fusion

Xiao Chen ¹ , Shane Shahrestani ¹ , Alexander Ballatori ¹ , Andy Ton ¹ , Zorica Buser ¹ , and Jeffrey C. Wang ¹

¹ Keck School of Medicine, University of Southern California, Department of Orthopaedic Surgery, Los Angeles, USA

Introduction: Obesity is a national pandemic within the USA that poses unique challenges for surgeons, patients, and healthcare systems. Several studies have assessed the influence of obesity on clinical outcomes following spine surgery, but no database research has comprehensively analyzed complication and readmission rates within different obesity classes. This study aims to quantify the influence of BMI on complication and readmission rates following lumbar spine fusion and to develop predictive models to estimate the cumulative risk of each successive BMI level on postoperative infection, wound complication, and readmission rates. Material and Methods: A retrospective cohort study was conducted using the 2013-2017 National Readmission Database. Patients who underwent elective lumbar spine fusion within the population-based sample were considered for inclusion. Exclusion criteria included non-elective lumbar spine fusions, malnourished, anorexic, or underweight patients, and surgical indications of trauma or neoplasm. Patients were grouped by BMI: 18.5-29.9 (controls), 30-34.9 (obesity I), 35-39.9 (obesity II), and ≥ 40 (obesity III). Multivariate regression was performed to analyze differences in complications and readmissions between groups. Predictive modelling was conducted to estimate the impact of BMI on 30- and 90-day infection, wound complication, and readmissions rates. Results: 86,697 patients were included for analysis, with an average age of 58.9 years and 58.9% of patients being female. Patients were grouped by BMI: 18.5-29.9 (non-obese controls), 30-34.9 (obesity I), 35-39.9 (obesity II), and ≥ 40 (obesity III). The obesity II group had significantly higher risks of infection (OR: 1.82, 95% CI: 1.28-2.62, P = .001) and wound injury (OR: 3.08, 95% CI: 1.70-6.18, P = .0006), and 30-day readmission (OR: 1.32, 95% CI: 1.11-1.58, P = .002). The obesity III group had significantly higher rates of acute renal failure (OR: 2.14, 95% CI: 1.20-4.06, P = .014), infection (OR: 2.43, 95% CI: 1.72-3.48, P < .0001), wound injury (OR: 3.76, 95% CI: 2.08-7.51, P < .0001), 30-day readmission (OR: 1.62, 95% CI: 1.36-1.93, P < .0001), 90-day readmission (OR: 1.53, 95% CI: 1.31-1.79, P < .0001), and 180-day readmission (OR: 1.47, 95% CI: 1.24-1.75, P < .0001) compared with controls. Predictive modelling showed cumulative increases of 6.44% in infection, 3.69% in wound injury, and 1.35% in readmission within 90-days for each successive BMI cohort. Conclusion: Progressively higher risks for infection, wound complications, and hospital readmission were found with each progressive BMI level. Acute renal failure was found to be significantly higher in the obesity III group compared to the non-obese controls. These findings should be taken into consideration for guiding preoperative planning and medical optimization, risk stratification within bundle-payment systems, and postoperative follow-up.

400

P183: Correlation Among Various Clinical Scoring Systems in Degenerative Lumbar Spinal Stenosis

Siddharth Gupta ¹ , Tungish Bansal ² , Shahrukh Khan ¹ , Abhishek Kashyap ¹ , Sumit Sural ¹

¹ MAMC and LNH Hospital, Department of Orthopedics, New Delhi, India

² AIIMS, NEW DELHI, Department of Orthopedics, New Delhi, India

Study Design: Observational study. Objectives: To investigate the correlation among various clinical scoring systems, in patients with degenerative lumbar spinal stenosis (LSS). Methods: Eighty two patients aged more than 40 years with clinico-radiological features suggestive of degenerative LSS were enrolled. All patients completed 9 clinical scoring questionnaires which included Oswestry Disability index(ODI),Swiss Spinal Stenosis(SSS) questionnaire, Quebec pain disability (QPD), Visual analogue Scale (VAS),modified Japanese Othopedic Association score ( mJOA), Pain disability index(PDI), Self-paced walking test (SPWT), EQ- VAS and Neurogenic Claudication Outcome score (NCOS). A comparison was done among various clinical scores and they were statistically analysed and correlated. Results: The mean age was 53.02 years and included 51 females (62.2%) and 31 (37.8%) males. A single level was involved in25.6% patients (21) had single level involvement, 47.56 % (39) had two level involvement and three or more levels were involved in 22 (26.8%) patients based on imaging. The QPD and SSS questionnaire had a significant strong positive correlation(r = .707, P = .000) with each other and a moderate correlation (P < .05, r > .3) with all other scores except NCOS. The VAS scale and SPWT had a moderate correlation with all clinical scores except NCOS (P < .05, r > .3). EQ- VAS has a moderate correlation with ODI, SSS, QPD, VAS and SPWT test (P < .05, r > .3). The ODI score has a moderate correlation with SSS scale, QPD scale, VAS, EQ VAS and SPWT (P < .05, r > .3). The PDI has moderate correlation with SSS, QPD, VAS, mJOA and SPWT test (P < .05, r > .3). The mJOA scale has a moderate correlation with SSS, QPD, VAS, PDI and SPWT (P < .05, r > .3). The NCOS scale did not show any significant correlation with any of the other eight scales. Conclusions: The VAS, QPD, SPWT and SSS questionnaire correlated strongly or moderately with all the clinical scores except NCOS. The other score like ODI, PDI, mJOA and EQVAS also correlated well with most of the other scores. The NCOS score did not demonstrate a clinically significant correlation with any of the other scores.

Keywords

Lumbar canal stenosis; NCOS; ODI; VAS; mJOA; self-paced walking test.

424

P184: Are Guidelines Important? Results of a Prospective Quality Improvement Lumbar Fusion Project

James Harrop ¹ , Thiago Montenegro ¹ , Glenn Gonzalez ¹ , Alexandra Emes ¹ , Ameet Chitale ¹ , Chengyuan Wu ¹ , Fadi Al-saiegh ¹ , Geoffrey Stricsek ¹ , Jack Jallo ¹ , Joshua Heller ¹ , Kevin Hines ¹ , Lucas Philipp ¹ , Sara Thalheimer ¹ , Srinivas Prasad ¹ , Umma Fatema ¹ , and Ashwini Sharan ¹

¹ Department of Neurosurgery, Philadelphia, USA

Introduction: U.S. healthcare is a volume-based inefficient delivery system. Value requires the consideration of quality, which is lacking in most healthcare disciplines. Material and Methods: All elective lumbar fusion cases, March 2018 - August 2019, were prospectively evaluated and categorized based on an evidence-based medicine (EBM) guideline for surgical indications. Cases were deemed EBM-concordant (management consistent with lumbar fusion EBM guidelines) or EBM-discordant for lumbar spine fusions. Baseline Oswestry Disability Index (ODI), along with clinical variables (age, gender, morbidity index (ASA), smoking status, surgeon, operative approach, procedure, and clinical indication for fusion), were collected. The minimum clinically significant difference (MCID) was defined as a reduction of ≥5 points in ODI. Correlation analysis identified variables predictive of improved 6-month ODI and multiple logistic regression identified multivariable-adjusted Odds Ratio (OR) of EBM concordance. Results: 325 lumbar fusion patients were entered with 6-month follow up data available on 309 (95%). 57% (n = 176) were female, median age 65 years (range: 57-72). The median preoperative ODI score was 24.4 (IQR=19-31 CI: 23.9-25.8), with median 6-month improvement of 7.0 points (IQR=4-13) (P < .0001). Based on ODI scores: 79.6% (246/309) improved, 3.8% (12/309) no change, and 16% (51/309) worsened. 191 patients had ODI-improvement reaching the MCID. 93.2% (288/309) cases agreed with the EBM guidelines, while 6.7% (21/309) did not. In multivariate analysis, EBM concordance (P = .0338), lower preoperative ODI (P < .001), lower ASA (P = .0056), and primary surgeries (P = .0004) were significantly associated with improved functional outcome. Age, BMI, smoking status, number of levels fused, approach, and surgeon were not significant predictors of meeting the MCID. EBM-concordance conferred a 3.04 (95%CI 1.10–8.40) times greater odds of achieving MCID in ODI at 6 months (P = .0322), adjusting for other factors. Conclusion: This analysis provides validation of an EBM guideline criteria to establish optimal patient outcomes and overall care for surgical treatment of lumbar fusions. The EBM concordant patients had a greater than three times improved outcome compared to those not meeting EBM fusion indication criteria.

446

P185: Time to Return to Work After Elective Lumbar Spine Surgery

Supriya Singh ¹ , and Raphaële Charest-Morin ¹

¹ Vancouver Spine Institute, Orthopedic Surgery, Vancouver, Canada

Introduction: Return to work (RTW) after elective lumbar spine surgery is largely arbitrary and recommendations for RTW do not rely on evidence-based medicine. The primary objective of this study was to describe time to RTW after elective lumbar spine surgery. Secondary objectives were to determine predictors of early return and no return to work after surgery. Methods: Using the Canadian Spine Outcomes and Research Network (CSORN) database, a retrospective study was done to analyze return to work for patients enrolled between January 2015 and December 2018. Return to work was analyzed for patients greater than age 18, who were employed, and undergoing one or two level elective lumbar spine surgery. Outcomes were assessed using survival analysis. Results: In the overall cohort, 1805 patients were included in the analysis. The median RTW was 61 days and 71% of the cohort returned to work after surgery. The median RTW to work after a discectomy, a laminectomy and a fusion was 51, 46 and 90 days, respectively. Predictive factors for early RTW included patient factors (male gender, higher education level, preoperative working status), and surgical factors (treated in Western Canadian province, non-fusion procedure). Conclusion: This study provides useful clinical information about RTW after elective lumbar spine surgery in the Canadian population. Most patients will return to work (71%) after elective lumbar spine surgery. The majority of patients will return to work within 7 weeks for non fusion procedures and 13 weeks for fusion procedures.

462

P186: Accuracy of Neuromonitoring During Percutaneous Cement Discoplasty

Gaston Camino Willhuber ¹ , Mariana Bendersky ² , Carolina Vilte ³ , Gonzalo Kido ¹ , Matias Pereira Duarte ¹ , Martin Estefan ¹ , Julio Bassani ¹ , Matias Petracchi ¹ , Marcelo Gruenberg ¹ , and Carlos Sola ¹

¹ Hospital Italiano de Buenos Aires, Potosí 4215, Buenos Aires, Argentina, Institute of Orthopedics “Carlos E. Ottolenghi,”, Ciudad Autónoma de Buenos Aires, Argentina

² III Normal Anatomy Department, School of Medicine, Ciudad Autonoma de Buenos Aires, Argentina

³ Hospital Italiano de Buenos Aires, Intraoperative Monitoring, Pediatric Neurology Department, Ciudad Autonoma de Buenos Aires, Argentina

Introduction: Percutaneous cement discoplasty is a minimally invasive procedure to treat low back pain due to advanced degenerative disc disease in elderly patients. Complications of this procedure has been described such as infection, vertebral fracture, cement leakage and nerve injury. Intraoperative neuromonitoring is used to detect the nerve root injury by irritation or compression during cannula placement or/and cement injection. The objective of this study was to assess the usefulness of neuromonitoring during discoplasty to detect new neurological compromise. Material and Methods: 100 consecutive patients were retrospectively analyzed, (30 males and 70 females, mean age of 76.3 ± 5.71 years). Inclusion criteria were as follows: mechanical low back pain with visual analogue scale (VAS) of at least 5 points and leg VAS score of less than 3, presence of partial or total intervertebral vacuum phenomenon according to the classification developed by the authors, patients with mild or without spinal stenosis based on Schizas’s classification. We excluded from this study cases with moderate or severe lumbar spinal stenosis, patients with leg VAS score of 3 or more, presence of prior neurological claudication, patients with incomplete neuromonitoring record as well as patients with previously known neurological deficit were also excluded. Variables such as age, sex, number of discoplasties and levels treated, extrapedicular and pedicular entry points were recorded. Sensitivity and specificity analysis were conducted. Results: Sensitivity to detect neurological injury was 82% (CI 95% 66-98), specificity was of 99% (CI 95%98-100) with a positive predictive value of .95 (CI 95% 85-100) and a negative predictive value of .97 (CI 95% 95-99). In 5 patients neurological compromise was not detected by neuromonitoring. Conclusion: Our study showed high sensitivity and specificity of neuromonitoring to detect neurological irritation during percutaneous discoplasty. Intraoperative neuromonitoring resulted an effective assistance during this minimally invasive procedure.

474

P187: Return to play after lumbar discectomy in non-professional athletes

Michel Kanas^1,2, Leonardo Garcia³, Rafael Bou Roujeile Campiolo³, Lucano Batoni Oliveira³, Nelson Astur^1,4, Marcelo Wajchenberg^1,2, Delio E. Martins^1,3

¹ Hospital Israelita Albert Einstein, Sao Paulo, Brazil

² Federal University of Sao Paulo, Sao Paulo, Brazil

³ Universidade Anhembi Morumbi, Sao Paulo, Brazil

⁴ Santa Casa de Sao Paulo, Sao Paulo, Brazil

Introduction: Lumbar disk herniation (LDH) is a condition that affects 2-3% of general population. The affected individual can be asymptomatic; or present low back pain and radiculopathy. Lumbar spine disc degeneration is more common in professional athletes, with a reported prevalence up to 58%, varying in different sports modalities. Most athletes return to play in a period between 3 and 9 months after conservative or surgical treatment. In the last years, general population increased the practice of high demand sports, however, there are no studies about their return-to-play rate after LDH treatment. The objective of the study was to evaluate return-to-play rate and time, after lumbar discectomy in non-professional athletes. Material and Methods: A digital questionnaire was sent to patients submitted to one or two levels open discectomy, in the last 5 years. After signing the informed consent form, the patients were instructed to answer the questionnaire with personal and clinical data, related with LDH treatment, and returning to sports practice. The information obtained was submitted to statistical analysis. Results: One hundred patients answered the questionnaire; from those, 65% practiced regular sport activities before surgery. After surgery, most patients (93%), had physiotherapy for rehabilitation. From patients who practiced sports before surgery, 75.38% returned to sports activities after the procedure; furthermore, 20% of those who didn’t practiced sports before, started after surgery. Just 14.29% returned before 3 months, 42.86% returned between 3 and 6 months, 23.21% returned between 6 months and one year, and 17.85% returned to sports practice after one year. Conclusion: A high return-to-play rate (75.38%) was observed after open lumbar discectomy in non-professional athletes, most of them (66.07%) took between 3 months to one year to return to sports activities. Compared to that described in literature for professional athletes, the returning rate was a little lower, and the time of return, somewhat slower.

478

P188: Experience in the Creation and Certification of a Clinical Care Center: Lumbar Decompression and Fixation Program

Luis Carlos Morales Saenz ¹ , Fernando Alvarado Gómez ¹ , Andres Rodriguez Munera ¹ , Maria Bedoya ¹ , Kenny Lopez Gomez ¹ , and Yuli Viviana Fuentes Barreiro ¹

¹ Hospital Universitario Fundación Santa Fe de Bogotá, Bogotá, Colombia

Introduction: Humans, regardless of the type of work, make mistakes, but these can be prevented if systems are designed that make it difficult for people to perform an action in an incorrect way and to promote doing it in an appropriate way. According to the report of the IOM, in USA, more than 1 million preventable adverse events occur each year, of which approximately 100,000 would cause serious harm to patients, and between 48,000 and 98,000 deaths could have been due to errors. For this reason, there is a latent need to create a clinical pathway for standardization, optimization, and simplification of the process of care of patients, in our case, patients with lumbar canal stenosis. Material and Methods: For more than 10 years, we work in gathering information and determining the processes to be carried out within a group of specialties, to later submit them to the accreditation standards stipulated by the Joint Commission International. The first step was to carry out a systematic review and an analysis of our own casuistry, for different points that influence the patient's follow-up, such as: 1. Creation of risk mitigation that is carried out in the pre surgical assessment, with each one of the patients for allows us to obtain a specific view of the patient regarding their comorbidities and risks prior to surgery. 2. Creation of indicators in an information management system that, is recorded and analyzed monthly 3. Evaluation of functionality scales in 3 times (pre-surgery - 6 months assessment - 12 months assessment), which indicate the success of the intervention in terms of functionality 4. Standardization of the surgical procedure and behavior within the surgery rooms. 5 Individualized rehabilitation. Results: In our institution, more than 2 thousand procedures have been performed and since the creation of the clinical care center in 2016, 128 procedures has been performed, with an average duration of 03:41:47 hours, 85 women and 43 men, average age of 68 years, average of hospital stay of 4.16 days. Regarding the annual proportion measured with the indicators, the following results were found completion of functional scales to patients of the clinical care center: 100%, administration and adequate suspension of antibiotic: more than 95%. patients who were reoperated within 90 days after their surgical procedure: 3.84%, infection of the operative site within 30 days after the surgical procedure: 3.84%, improvement with rating scales for functionality, quality of life and emotional state (Oswestry, Eq5D and Zung), more than 85% as consolidated. Conclusions: Standardizing a patient care process and submitting to accreditation standards by external entities allows improving the patient's clinical results in terms of protocol adherence to ensure a high level of satisfaction and quality of life. Under the standards of safety and quality in patient care, the Joint Commission International granted in December 2016 the accreditation for the lumbar decompression and fixation program, being the first accredited clinical care center, focused on the management of this pathology worldwide.

481

P189: The Impact of Frailty on Patient Reported Outcomes Following Elective Degenerative Spine Surgery

Philippe Beauchamp-Chalifour ¹ , Alana Flexman ² , John T. Street ² , and Raphaële Charest-Morin ²

¹ Université Laval, Orthopaedic Surgery, Quebec City, Canada

² University of British Columbia, Vancouver, Canada

Introduction: Frailty has been shown to be a risk factor for peri-operative adverse events (AEs) in patients undergoing various types of spine surgery. However, its relationship with Patient Related Outcomes (PROs) remains unclear. The primary objective of this study was to determine the impact of frailty on PROs in patients undergoing surgery for thoraco-lumbar degenerative conditions. The secondary objective was to determine the association between frailty, baseline PROs and perioperative AEs. Material and Methods: This is a retrospective study of a prospective cohort of patients >55 years old who underwent surgery between 2012 and 2018. Patient data and PROs (EQ-5D, SF-12 (PCS and MCS), ODI, back and leg pain NRS) were extracted from the Canadian Spine Outcomes and Research Network registry for patients treated at a single academic centre. Frailty was calculated using the modified frailty index (mFI) and patients were classified as frail, pre-frail and non-frail. A generalized estimating equation (GEEs) regression model was used to assess the association between patients’ baseline frailty status and PRO measures at 3 and 12 months. Results: 293 patients were included with a mean age of 67 ± 7 years. Twenty-two percent of the patients (n = 65) were frail, 59 % (n = 172) were pre-frail and 19% (n = 56) were non-frail. At baseline, the three frailty groups had similar PROs, except for the PCS (P = .003) and the ODI (P = .02), which were worse in the frail group. Frail patients experienced more major AEs (P < .0001). However, despite the increased incidence of AEs, there was no association between frailty and the post-operative PROs (EQ-5D, PCS, MCS, ODI, back and leg pain NRS scores) at 3 and 12 months (P ≥ .05). In general, PROs improved statistically at 3 and 12 months (with the exception of the MCS which remained stable over time). Conclusion: Although frailty predicted postoperative AEs, the mFI did not predict patient related outcomes after spine surgery in the degenerative thoraco-lumbar spine population over 55 years old.

531

P190: Anterior Lumbar Interbody Fusion with Porous Titanium Interbody Cages is Associated with Equivalent Fusion Rates and Patient Reported Outcomes as Bone Morphogenetic Protein-2

Athan Zavras ¹ , Zakariah Siyaji ¹ , Ali Piracha ¹ , Talha Qadri ¹ , Michael Nolte ¹ , Arash Sayari ¹ , Syeda Qadri ¹ , Maheen Khan ¹ , and Matthew Colman ¹

¹ Rush University Medical Center, Orthopedic Surgery, Chicago, USA

Introduction: Recombinant human bone morphogenetic protein 2 (BMP-2) has been used with increased frequency for Anterior Lumbar Interbody Fusion (ALIF), diminishing the role for iliac crest bone autograft and associated morbidities. However, concerns regarding the use of BMP-2 include off-label use, elevated cost, and adverse outcomes. As a paradigm change, we considered that porous ingrowth implants without the use of exogenous biologics may have applications in this area. These implants are widely used within the fields of orthopedics to bond host bone via ingrowth without external biologic assistance. This mechanism of healing is in stark contradistinction to the traditional paradigm of trans-cage BMP-enhanced arthrodesis through a “graft window”. This study compared postoperative and radiographic outcomes between patients undergoing ALIF with and without the external assistance of BMP-2. Methods: This study retrospectively examined patients who underwent 1- or 2-level ALIF with or without the use of BMP-2. Procedures were performed from 2014to2020 with minimum follow-up of 6-months. Patient demographics, comorbidities, postoperative complications, and pre- and postoperative patient-reported outcomes (PROs:OswestryDisability Index [ODI], Visual Analog Scale [VAS]-back pain, VAS-leg pain, 12-item Short Form Survey, Veterans RAND 12 Item Health Survey) were assessed. Rates of arthrodesis and reoperation were assessed using radiographs and CT. Preoperative and postoperative radiographic parameters wereevaluated for differences in spinopelvic alignment and correction. Multivariateregression controlled for baseline characteristicsand differences in clinical outcomes associated with procedural methods. The threshold for statistical significance was set to P < .05. Results: Thirty-two (19 female, 13 male) and 43 (13 female, 30 male) patients were assessed with and without BMP-2, respectively.There were no significant differences observed in PRO surveys between cohorts. Radiographic fusion (BMP-2, 90%, non-BMP-2, 91%,P = .776) and revision (BMP-2: 9.09%, non-BMP-2: 18.75%,P = .293) rates were similar for both cohorts. For the BMP-2 cohort, 3 of 4 revisions were for vertebral body fracture secondary to subsidence, while 1 was for new-onset radiculopathy. The non-BMP-2 group observed 4 revisions for fracture caused by cage subsidence and 2 for persistent radiculopathy. Two patients in the BMP-2 cohort had secondary surgery for ASD at the 2 levels cephalad to the instrumented level, while none of thenon-BMP-2patientsdeveloped ASD by the end of the assessed follow-up period. Long-term radiographic assessment noted a greater magnitude of lordotic correction innon-BMP-2patients(34.51±9.86) than theBMP-2cohort(26.19±9.28,P = .001), as well as significantly greater increases in middle and posterior disc heights at L4-L5, and anterior, middle, posterior, and foraminal heights at L5-S1. No differences in subsidence were evident at the superior(P = .458) or inferior endplate (P = .154). Conclusion: We observed no significant differences in patient-reported outcomes, rates of arthrodesis, or reoperation between ALIF patients treated with and without BMP-2. Spinopelvic alignment and disc heights showed improved lordotic correction and disc heights at L4-L5 and L5-S1 in thenon-BMP-2cohort, suggesting better structural integrity with non-enhanced autologous fusion. The use of porous titanium implants without external biologics demands meticulous surgical technique but is an intriguing paradigm change which may produce similar outcomes at lower costs.

549

P191: Influence of Depressive Symptoms on the Outcome of Lumbar Spine Fusion. A 5-Year Follow-Up Study

Leevi Toivonen ¹ , Arja Häkkinen ² , Liisa Pekkanen ³ , Hannu Kautiainen ² , Anne Salonen ¹ , and Marko Neva ¹

¹ Tampere University Hospital, Tampere, Finland

² Jyväskylä University, Jyväskylä, Finland

³ Central Finland Hospital District, Jyväskylä, Finland

Study Design: Prospective follow-up study. Objective: The aim of this study was to assess if depressive symptoms change the outcome of lumbar spine fusion (LSF) surgery at a 5-year follow-up. Summary of Background Data: Previous reports of the influence of depressive symptoms on the results of spine surgery are controversial, but the patient characteristics and indications for surgery varied widely between the studies. The influence of depressive symptoms on the 5-year outcome of LSF has not been studied. Methods: The study was based on data from a local LSF database from 2 hospitals comprising 392 consecutive patients (mean age 61 years, 277 women) who underwent an instrumented LSF and fulfilled the 5-year follow-up. At the 5-year follow-up, the patients were compared with a control group from the general population (n = 477, age, sex and residential area matched) extracted from Official Statistics of Finland. The prevalence of depressive symptoms was evaluated using the Depression Scale (DEPS; 0-30) and disability was evaluated by the Oswestry Disability Index (ODI; 0-100%). A DEPS score ≥ 12 was considered to indicate depressive symptoms. Results: Before surgery, 35% of the patients had depressive symptoms. The proportion diminished to 13% at 3 months postoperatively and increased to 24% at 5 years. In the population, the prevalence was 11% at baseline and 10% at the 5-year follow-up. The preoperative ODI was 54 in the patients with depressive symptoms, and it was 41 in the patients with no depressive symptoms. The changes at 5-year follow-up were -20 and -18, correspondingly. The same congruence was preserved when analyzing short and long fusions separately. These changes were statistically and clinically significant. In the control population, the ODI remained around 24 in depressive people and 10 in non-depressive people. Conclusions: Our data suggest that patients with and without depressive symptoms may benefit equally well from LSF.

Keywords

Depressive symptoms, Depression scale DEPS, Disability, Lumbar spinal fusion, Surgery

Level of Evidence: 3

557

P192: Improved Efficacy of TLIF Procedures Due to the Use of a New Device for Disc Space Preparation: Preliminary Cadaver Study and a Single-Center Retrospective Study with 208 Patients

John Peloza ¹ , Michael Millgram ² , Nahshon Rand ² , Richard Guyer ³ , Jean Charles Le Huec ⁴ , and Ely Ashkenazi ²

¹ Center For Spine Care, Dallas, TX, USA

² Assuta Medical Center, Israel Spine Center, Tel Aviv, Israel

³ Texas Back Institute, Plano, TX, USA

⁴ Bordeaux University School of Medicine, Bordeaux, France

Introduction: Transforaminal Lumbar Interbody Fusion (TLIF) procedures are commonly performed in the US, increasing in number as the population ages. A new powered FDA-approved device, designed to clean the endplates for improved cartilage removal and shorten the time required for disc removal, can improve procedure outcome and reduce the time it requires. This study aims to assess the effect of device use in a preliminary cadaver study and a retrospective single center study. Material and Methods: The records of 208 single-level TLIF procedures conducted in a single hospital during 2012-2019 were reviewed. 143 procedures were conducted using the device and 65 control procedures were conducted using traditional tools. Surgery duration, length-of stay and complication rates were extracted from the records and compared between both groups. Clinical outcome was assessed using pain and disability scores. In addition, a preliminary cadaver study was conducted on five lumbar levels by two surgeons. The number of instrument passes required for each surgeon with and without the device was measured and compared. After the conclusion of the procedures, the cadaver disc-spaces were cut open and the endplates were observed for any perforations. The area of prepared endplate was calculated from endplate images. Results: The analysis revealed a statistically significant reduction of 23 minutes in surgery duration after controlling for procedure year and patient age, sex, smoking status and operated level. A reduction of .44 days in the length-of-stay was noted (P = .5). In addition, the device group had less complications (2.8% vs 6.2%, P = .21) and less readmissions (2.1% vs 3.1%, P = 67). Fewer patients in the device group (2.8% vs 9.2%, P = .04) complained on post-operative pain or weakness in the leg, possibly due to the shorter surgery time and reduced need to retract the nerve root. Follow up pain and disability scores were similar for both groups. Revision surgery rates due to incomplete disc removal or pseudarthrosis were similar in both groups (1.5% and 1.4%, P = .94). The number of instrument passes required to clean the cadaver disc-spaces was reduced by 18.5 on average when the device was used. Endplate perforation occurred in 1 out of 6 endplates in the device levels (16.7%) and in 1 out of 4 endplates in the control group (25%). The relative area of prepared endplate was higher by 83% when the device was used. Conclusion: The study suggests that the device use can lead to a shorter procedure and hospitalization and potentially also reduced the complication rate, without deteriorating the clinical outcome.

573

P193: Prevalence of Degenerative Spondylosis in Whole Body SPECT CT in a Consecutive Cohort of Patients Presenting with Cancer Under 60 years of Age

Atharv Patankar ¹ , Nikolaos Papadakos ² , Nigel Beharry ² , Cristina Lupu ³ , Jason Bernard ³ , Timothy Bishop ³ , Bisola Ajayi ³ , and Darren Lui ³

¹ St. George's University Hospital, Student, London, United Kingdom

² St. George's University Hospital, Radiology, London, United Kingdom

³ St. George's University Hospital, Orthopaedics, London, United Kingdom

Introduction: The prevalence of radiological degenerative spondyloarthropathy is well described in hospital-based cohorts using MRI. CT SPECT can detect degenerative spondylosis (DS) but the high dose of radiation makes this an unsuitable test for routine investigation. This study aims to determine the prevalence of DS in a consecutive cohort of cancer patients under the age of 60. Material and Methods: Whole Body SPECT CT between 2015 and 2019 were examined. 27% were under 60 years old. Inclusion: neoplasia. Exclusion criteria included: inflammatory disorders, trauma, infection. Reports were examined for degenerative spondyloarthropathy at the intervertebral disc level or facet joints and subdivided into anatomical locations. Results: 2591 patients had SPECT CT between 2015 and 2019. 1185 patients with a Whole Body SPECT CT were examined for DS and metastases. 325 patient < 60 years identified. 170 presented with cancer. Mean age of patients was 51 (Range 1-60). 69% of patients under 60 present with a degree of Spondylosis. Cancers included: breast 62%, prostate 21%, other 17%. Ages 4-30y showed no spondylosis. Ages 31-40 y (n = 15) 5 patients (33%) had degenerative spondylosis, 4 (80%) in thoracic and 2 (40%) in lumbosacral spine. Ages 41-50 y (n = 47 patients) 25 (51%) had degenerative spondylosis, 20 (80%) lumbosacral, 13 (52%) thoracic, 5 (25%) cervical spine, and 5 (25%) in the sacroiliac joint (SIJ). 1 patient (4%) had degeneration in every region of the spine. Ages 51-60 y (n = 106) 87 (82%) had degenerative spondylosis, 81 (93%) lumbosacral, 60 (69%) thoracic, 26 (30%) cervical spine, and 15 in SIJ. 17 patients (16%) had degeneration in every region of the spine. 15/170 (8%) patients presented with back pain. 5/15 (33%) cases had metastases. Conclusion: First presentation cancer patients in the young are likely to have the same prevalence of spondylosis as the general population. As expected, no degenerative spondylosis was noted in the very young. Prevalence increased from age 31 onwards. From 30% in the 3rd decade to 50% in the 4th decade and 80% in the 5th decade. Degenerative changes were more prevalent in the thoracic spine when young, but incidence increased as age progressed. The strength of this study is the large cohort the patients are selected from and the ability to analyse CT SPECT scans in an otherwise young population who otherwise would not have this investigation modality for back pain.

578

P194: OLIF Combined with Anterior Screw Fixation for Surgical Treatment of Lumbar Degenerative Scoliosis

YuTong Gu ¹ , Wu Che ¹ , Liang Zhang ¹ , and Yichao Wang ¹

¹ Zhongshan Hospital Fudan University, Shanghai, China

Introduction: OLIF (Oblique Lateral Interbody Fusion) combined with percutaneous pedicle screw fixation has been used to treat lumbar degenerative scoliosis, which has some advantages including less damage of paraspinal muscles and bone structures, less blood loss, faster recovery, bigger cage with higher fusion rate because of more touch surface between endplate of vertebra and cage and more graft bone, compared with open surgery of osteotomy, PLIF or TLIF and pedicle screw fixation. In addition, bigger cage of OLIF has better distraction ability of intervertebral space helpful for correction of scoliosis, reduction of spondylolisthesis and enlargement of spinal canal, which can make neurologic decompression achieved. However, OLIF needs additional pedicle screw fixation for biomechanical stability, which results in more invasiveness, longer operative time under general anesthesia for two procedures with different position, even two stages with twice tracheal intubation. We designed OLIF combined with anterior screw fixation in the same approach for the treatment of lumbar degenerative scoliosis in order to reduce the invasiveness and the duration of operation. The purpose of study is to evaluate the feasibility, efficacy and safety of OLIF combined with anterior screw fixation for lumbar degenerative scoliosis. Materials and Methods: Eight cases of lumbar degenerative scoliosis (coronal Cobb angle >10°) underwent OLIF (using cage and allograft bone) combined with anterior screw fixation for L2-5 through the mini approach in a right lateral position without real-time monitoring by electromyography in this study. We assessed statistical differences between preoperative and postoperative (12-month) coronal and sagittal parameters. Results: The duration of operation was 217.5 ± 22.7 minutes. There was a mean blood loss of 110 mL (50–600 mL). The incision length was 4.6 ± .4 cm. The mean stay at the hospital was 6 days (5–8 days). The average follow-up duration was 13.5 (12-18) months. At 1-year follow-up, all patients achieved statistically significant improvement in coronal Cobb angle (from 22.7±4.8∘ to 9.8±3.7°, P < .001), apical vertebra translation (AVT) (from 2.5 ± .8 cm to 1.5 ± 1.0 cm, P < .005), coronal vertical axis (CVA) (from 2.2 ± 1.6 cm to .6 ± .4 cm, P < .05), sagittal vertebral axis (SVA) [from 6.3(.2-23.4) cm to 2.3(.1-9.6)cm, P < .05], thoracic kyphosis (TK) (from 25.2 ± 4.0° to 28.7±4.8°, P < .05), lumbar lordosis (LL) (from 29.4 ± 9.5° to 37.9 ± 8.5°, P < .001), pelvic incidence (PI) (from 52.4 ± 13.1∘ to 49.0 ± 11.3°, P < .05), pelvic tilt (PT) (from 28.4 ± 6.9° to 22.4 ± 5.7°, P < .001) and PI-LL mismatch (from 23.0 ± 11.4° to 11.1 ± 8.9°, P < .001). For the clinical evaluation, VAS for back pain [from 8(6-10) to 1(0-2), P < .001] and ODI (from 55.6 ± 8.7 to 21.1 ± 3.4, P < .001) improved significantly after surgery. Fusion grades based on the Bridwell grading system at 1-year follow-up were grade I in 17 segments (70.8%), grade II in 7 segments (29.2%). No patients had nerve damage and no failure of instruments was observed. Conclusion: OLIF combined with anterior screw fixation is a good choice of minimally invasive surgery for lumbar degenerative scoliosis.

625

P195: Posterior Lumbar Interbody Fusion with Laminoplasty in the Treatment of Lumbar Isthmic Spondylolisthesis

Hamdan Abdelrahman ^1,2 , Seyed Emadaldin Sadat ³ , Ahmed Shawky Abdelgawad ¹ , Branko Krajnovic ³ , and Ali Ezzati ⁴

¹ Asiut Universty Hospitals, Asiut, Egypt

² Helios Hospitals Erfurt, Spine Surgery, Erfurt, Germany

² Helios Hospitals Erfurt, Spine Surgery, Erfurt, Germany

⁴ Helios Hospitals Erfurt, Erfurt, Germany

Introduction: The technique for surgical treatment of isthmic spondylolisthesis (ISL) is still controversial. Different opinions have been expressed by various authors on timing, type of surgery, type of grafts that are used as well as on whether reduction should be applied or not and the value of reduction. In light of these data we describe our technique in the treatment of ISL and its outcomes. Patients and methods: Between 12/2012 and 12/2017, we examined 70 consecutive patients that had been operated in our clinic due to ISL. The patients have been assessed clinically and radiologically. The same posterior surgical technique was used in all patients (interbody fusion using bone substitute and cage, reduction of the olisthesis and reinsertion of the lamina). Surgical technique: In prone position, after exposure of the spine posteriorly and transpedicular screw fixation of the affected segment, the lamina of the affected level was removed en-bloc through the facet joint and site of lysis on both sides. Decompression of the nerve roots on both sides followed by discectomy and preparation of the endplates for bone substitute and cage was performed. Partial reduction of the olisthesis could be achieved through the discectomy and additional reduction through the application of lordotic rods. Finally after preparation of the lamina and removal of the cartilage on the joint surfaces the lamina was placed and fixed through small screws 2.7mm to the facet joint on both sides. Results: The mean age of the 44 females and 26 males was 53.2 years (18-78). Main complaint at the time of presentation was low back pain (mean VAS 5.9/10) in 59 patients with mean duration of 11.9 months. Leg pain was found in 57 cases; L5 radicular pain in 46 of them. Four patients had foot weakness due to foraminal disc herniation. Olisthesis grade I was seen in 36 patients, grade II in 24 and grade III in 10 cases. The technique was performed in 57 patients for L5/S1, in 10 patients for 4/5, in 3 patients for L4-S1. Fusion of adjacent degenerative level was done in 11 cases. Mean operative time was 182 min. with a blood loss of 630 ml. complete reposition could be obtained in 60 patients. Three patients had dural tears intraoperatively, one patient had foot weakness postop. that improved completely within one week. Out of 2 Patients with superficial wound infections one needed revision surgery. Solid fusion was found in 65 patients at the last FU. Three patients developed symptomatic screw loosening of L5 which had to be re-operated. VAS reduced to 3/10 before discharge and to 1.2 at the last FU (mean of 20.5 months). Conclusion: Removal of the lamina facilitates decompression of the nerve roots and enables reduction of Olisthesis. The use of bone substitute prevents donor site complications. The laminoplasty preserves the osseous structures of the posterior column and prevents scar formation. It also facilitates performing the revision surgeries.

635

P196: Transtubular Translaminar Approach for Lumbar Disc Herniation in the Hidden Zone

Hamdan Abdelrahman ^1,2 , Seyed Emadaldin Sadat ¹ , Ahmed Shawky Abdelgawad ^1,3 , Branko Krajnovic ¹ , and Ali Ezzati ¹

¹ Helios Hospitals Erfurt, Erfurt, Germany

² Asiut Universty Hospitals, Asiut, Germany

³ Asiut Universty Hospitals, Erfurt, Germany

Introduction: Although lumbar disc herniation (LDH) generally occurs without migration of the fragment, in 10% of the cases, this circumstance might happen. The surgical approach for these LDH in the preforaminal and foraminal zones „Hidden Zone „is controversial. The standard surgical procedures for removal of such LDH include interlaminar exposure with partial or complete resection of the upper hemilamina or facet joint and weakness of the pars interarticularis. We present our experiences with the translaminar approach to this entity of lumbar disc herniation using a tubular retractor system. Patients and Methods: Between January 2013 to January 2018, 55 patients (25 women and 30 men) with cranially migrated LDH in the preforaminal and foraminal zones were operated upon trans-tubular translaminar microscopic assisted percutaneous nucleotomy (TL-MAPN). The cases with associated instability, extraforaminal LDH or canal stenosis were excluded from the study. The outcome measures were: (1) self-reported measures: VAS (0-10, back and leg), (2) functional measures: ODI and Odom´s criteria. Results: The mean age was 58 years (36-85). The most commonly affected level was L4/5 (22 patients). The herniation was preforaminal in 18, foraminal in 19 and both in 19 patients. Two patients were already operated via interlaminar approach at the same level of the prolapse. The mean preoperative VAS for leg pain was 7 (4-9), which improved to 0 (0-3) postoperatively. The average operative time was 58 minutes. Dural injury occured in one patient, treated with dural patch. Motor weakness (affecting the exciting nerve root) was found in 36 Patients preoperatively, which improved at least one grade in 34 patients (neurological improvement rate (NIR) of 94%). There was a significant improvement in the mean ODI values, from 49.1 preoperatively to 10.5 postoperatively (P < .001). According to Odom’s criteria, 50 patients (90%) had excellent results, 4 good and one fair (with persistent muscle weakness). One Patient was reoperated at 28 months postoperatively as fusion surgery above the level of TL-MAPN. Conclusion: TL-MAPN is safe and effective technique for LDH in the hidden preforaminal and foraminal zones, because it resolves the symptoms without jeopardizing the stability. The technique is a muscle-splitting minimally invasive approach using tubular working canal that reduces surgical trauma and postoperative pain, especially in obese patients, and prevents instability with less morbidity. Complications, recurrence and reoperation rate are less compared to microsurgical open or endoscopic techniques.

664

P197: Our Initial Experience with XLIF Cases—Clinical and Radiological Outcome

Rawan Masarwa ¹ , Ofir Uri ¹ , and Eyal behrbalk ¹

¹ Hillel Yaffe Medical Center, Orthopaedic Department, Hadera, Israel

Introduction: Extreme lateral interbody fusion (XLIF) has been gaining acceptance over the past decade for the treatment of adult degenerative spine deformity. By its minimally invasive nature XLIF offers many advantages over the more familiar anterior lumbar interbody fusion (ALIF), however, it is a technically demanding procedure and associated with a steep lurning curve. We present our first series of patients who underwent XLIF procedure for degenerative lumbar disease in our institution. Methods: Twelve patients underwent XLIF procedure using the MFAST XLIF cage system between February and September 2019. A single-level XLIF was performed in 5 patients, 2-level XLIF in 3 patients and 3-level XLIF in 4 patient (overall 23 cages were inserted). The cohort included 6 men and 6 women with a mean age of 69 ± 7 years (range, 61 to 81 years) and a mean BMI of 26 ± 4 Kg/m² (range, 23-3 Kg/m²). The mean postoperative hospital stay was 6 ± 2 days (range, 5-10 days). Clinical and radiographic data were prospectively collected and retrospectively reviewed at a mean follow-up of 6 months (range, 3 to 10 months). Results: Postoperatively the mean pain level decrease from 8.8 to 4.6 (P = .003) and the mean Oswestry disability index decreased from 51 to 36 (P = .04). L4-5 lumbar disc height increased postoperatively from 5.6 ± 2.3 mm to 12.4 ± 1.3 mm. L4-L5 neural canal height increased from 13 ± 4 mm to 18 ± 5 mm (P < .001). Lumbar lordosis increased from 39 ± 15 to 46 ± 16 degrees (P < .001). Cage subsidence was noticed in one patient at 3-month follow-up radiographs. There was no case of infection and no patient required revision surgery. Conclusion: XLIF procedure for degenerative lumbar disease resulted in improved clinical and radiographic outcomes at short-term follow-up with an acceptable rate of complications. Despite these encouraging results longer follow-up is required in order to evaluate patients outcome over time.

670

P198: Correlation Between Degenerative Diseases of the Lumbar Spine and Types of Lumbar Lordosis

Nelson Astur ^1,2 , Bruno Braga Roberto ¹ , Alberto Gotfryd ^1,2 , Michel Kanas ^1,3 , Delio E. Martins ^1,4 , and Marcelo Wajchenberg ^1,3

¹ Hospital Israelita Albert Einstein, Orthopaedics - Spine Group, Sao Paulo, Brazil

² Santa Casa de Sao Paulo School of Medical Sciences, Department of Orthopaedics and Traumatology, Sao Paulo, Brazil

³ Universidade Federal de Sao Paulo, Department of Orthopaedics and Traumatology, Sao Paulo, Brazil

⁴ Universidade Anhembi-Morumbi, School of Medicine, Sao Paulo, Brazil

Introduction: Low back pain is an increasingly common social and economic problem today. One of the factors related to low back pain are degenerative changes of the lumbar spine. Sagittal alignment of the spine has been related to specific degenerative diseases of the spine. Roussouly described the variations in sagittal alignment and classified lumbar lordosis into 4 types, but did not statistically correlate it to types of degenerative lumbar spine disease. Therefore, the objective of this study was to evaluate a relationship between different types of degenerative spine diseases and lumbopelvic biomechanics, according to type of lordosis. Material and Methods: This is a retrospective study of patients medical records and imaging studies. Patients with a diagnostic of degenerative lumbar spine disease referred to us during the period of 201X to 201X without primary spine surgery were included. Based on patients’ full lateral spine radiographs and magnetic resonance imaging (MRI) study, we measured pelvic and sagittal alignment parameters and classified their lumbar lordosis into four types according to Roussouly. We diagnosed specific degenerative lumbar spine disease after MRI analysis as Lumbar Disc Herniation (LDH), Stenosis (St), Degenerative Disc Disease (DDD), Spondylolisthesis (SL), and Facet Joint Arthropathy (FJA) and correlated it to type of lumbar lordosis. Statistical tests, such as chi-square, were performed and the types of curvature and diagnostics used were recorded by absolute frequencies and reported for a general sample and by type of treatment. Results: A total of 418 patients were enrolled, 203 females and 215 males. There was 47 (11.2%) patients with type I lordosis, 159 (38%) patients with type II, 168 (40.2%) with type III, and 44(10.5%) type IV. Main diagnosis found was lumbar disc herniation (52.4%), followed by facet joint arthropathy (22.7%) and stenosis (9.8%). LDH was mostly seen in patients with type III lordosis. Spondylolisthesis was more common in type IV lumbar lordosis. Higher sacral slopes lead to higher number of patients with Spondylolisthesis (Types II, III and IV). A higher rate of surgical treatment was significantly indicated for Roussoly type I and II patients compared to conservative treatment, representing 64 and 56%, respectively. Conservative treatment was more common in groups III and IV (58 and 59%, respectively). There was 9 patients with any degenerative spine changes in their MRI and had no diagnostic. There was no statistical significance that could correlate diagnose with type of lumbar lordosis. Conclusion: Most frequent type of lordosis in a sample of patients with degenerative lumbar spine disease are types III and II. Lumbar disc herniation seemed more frequent in patients with type II or III lumbar lordosis. Surgical treatment is more frequent in types I and II.

681

P199: Aged-Related Differences in Clinical Outcomes of Lumbar Discectomy

Rawan Masarwa ¹ , Ofir Uri ¹ , and Eyal behrbalk ¹

¹ Hillel Yaffe Medical Center, Orthopaedic Department, Hadera, Israel

Background: Lumbar discectomy is a common and effective treatment for symptomatic disk herniation. It has been suggested that age may be a factor affecting the outcome of discectomy. The purpose of this study was to evaluate age-related differences in clinical outcomes of patients undergoing lumbar discectomy for chronic radicular pain resulting from lumbar disc herniation without neurological compromise. Method: Seventy-three patients (25 females) with chronic lumbar radiculopathy without neurological deficit underwent non-urgent single level lumbar discectomy in our institution between 2014 and 2017. Outcomes were retrospectively reviewed after a mean of 32 ± 17(13-48) months and compared between younger patients aged 30-50 years and older patients aged 50-70 years. Results: Pain level, Oswestry Disability Index and SF-12 scores improved significantly after the surgery in both younger and older patient groups. There were no significant differences in the outcomes measured between the groups before the surgery and after the surgery in both early post-operative follow-up and late post-operative follow-up. Conclusion: Lumbar discectomy improved function and decreased pain level to similar extent in both younger and older patients suffering from radicular symptoms related to lumbar disc herniation.

699

P200: Outcomes of Osteoporotic Thoracolumbar Fractures with Neurological Deficits: A Single Center Experience

Abhinandan Reddy Mallepally ¹ , Nandan Marathe ² , Kalidutta Das ¹ , and Harvinder singh Chhabra ¹

¹ Indian Spinal Injuries Center, Spine Services, New Delhi, India

² Toronto Western Hospital, Neuroscience Centre, Orthopaedics, Toronto, Canada

Introduction: Thoracolumbar junction (T11–L2), being a transitional zone is usually the most affected in osteoporosis and manifests with a variety of neurological symptoms as the level of injury may involve spinal cord, conus medullaris and cauda equina. The ideal surgical strategy has not been sufficiently investigated and remains controversial, due to the fragile bone, altered physiology of old age, poor functional reserves, comorbidities, cognitive dysfunction, pre-existing spinal deformity, fragile skin, and coexisting degenerative spinal diseases. In the present study, we discuss outcomes of such patients in terms of neurological and functional recovery, radiological improvement and complications on long-term follow up after surgical treatment. Materials and Methods: It is a retrospective study with prospective follow-up conducted on 124 patients (78/F, 46/M) during January 2016 to December 2018. Of 154 patients, 22 patients were lost to follow up and 8 patients died, the remaining 124 eligible patients with minimum 2 year follow-up were recruited and data was analysed for demographics, clinical presentation, intervention and outcomes. Plain radiographs were reviewed before surgery, immediately after surgery, and at 3 to 6 months interval after surgery up to latest follow up. Radiological outcomes in the form of focal kyphosis angle was obtained using Cobbs method, and vertebral height restoration on lateral plain radiographs. Instrumentation related complications like screw cut out, implant loosening, rod breakage and also adjacent segment fractures/ degeneration were assessed. Results: 124 patients were assessed. There was no history of injury in 30.6% patients. A total of 141 levels of vertebral fractures were detected, D12/68), L1/38), D11/19), L2/11 and D10/5. Bowel and bladder involvement was present in 80 patients. In 12 patients, were on steroid intake due coexisting diseases. Kümmells disease was seen in 67% patients. 51 patients out of 83 (58.6%) and all the patients on steroids and hypothyroid patients had Kümmells disease as evident on MRI. 31 patients were classified as ASIA-B, 75 as ASIA-C, and 18 as ASIA-D. The mean preoperative kyphosis was 27.120 ± 9.63°. There was improvement of an average of 13.5° ± 6.870 in the immediate post-operative period and at the final follow up kyphosis was (13.70 ± 7.290) with a loss of correction by 2.850 ± 3.7°. The height restoration at final follow up was 45.4% ± 18.29. 30% had short segment fixation and 70% long segment fixation. Thirty seven received posterior indirect decompression via ligamentotaxis and stabilisation only. 23 patients in total received PMMA augmented fixation. 92% of the patients n = 114 improved by at least one grade post operatively. All the patients with ASIA-D improved to ASIA-E. 64% with ASIA-C neurology improved to ASIA E. 16 patients’ experienced post-operative complications. Conclusion: Single stage posterior approach with combination of direct decompression or indirect postural reduction, balloon kyphoplasty and short segment posterior instrumentation is a reliable and effective procedure and allows for a safe reconstitution/ preservation of neurological function in patients with osteoporotic kyphotic fracture and correct deformity in elderly patients in poor general condition who are at high risk for serious complications.

735

P201: Early Postoperative Rehabilitation. New Trends in Treatment of Lumbar Spine Herniation

Alina Reutova ¹ , Dmitry Dzukaev ¹ , Ivan Khutornoy ² , and Anastasia Khokhlova ¹

¹ City Clinical Hospital 67 n.a. L.A.Vorokhobov, Moscow Spine Center, Moscow, Russian Federation

² High school of medicine Lomosov University, Moscow, Russian Federation

Introduction: Great number of world studies have shown the necessity of prolonged restriction of physical activity for 4-6 weeks in order to decrease the risk of reherniation after microdiscectomy in one of the lumbar spine segments. However, we offer another trend in the rehabilitation of this category of patients and presenting the evidence of the effectiveness of early rehabilitation measures. Material and Methods: The study was built as a prospective and carried out from 2014 to 2019. The study involved 176 patients aged 18-45 years who underwent microdiscectomy at the level L4L5. Patients were offered to undergo 15 therapy sessions that were started on the 3rd day after the surgery: 30-minute sessions with an instructor in the gym and swimming pool with a one-hour break between them. Exercises were selected individually depending on the surgical details. Original techniques made it possible to strengthen the muscles of the anterior abdomen and lower back, without inducing any pathological effect on the operated segment. Daily dynamic monitoring of patients was carried out. Statistical analysis was performed using MedCalc (version 11.2, 2011 MedCalc Software, Ostend, Belgium), MS Excel 2016. Quantitative variables were represented in format of median, mean and interquartile range, qualitative were presented as a proportion (%). A graphical representation of quantitative variables was implemented using "box-andwhiskers" plot type charts. Qualitative variables were presented in the form of pie charts with reflected percentages of categories for each of the qualitative variables. Results: Participants of this study, who underwent rehabilitation treatment, had a significant improvement in physical activity indicators in already 1 month after the surgery. Most professional athletes began full training after 1 month from the start of rehabilitation. Conclusion: Individually selected physical exercises in the early postoperative period (with an instructor in the gym and swimming pool) in patients after L4L5 microdiscectomy are the key factor of successful rehabilitation and allow individual to return quickly to active life and professional activity.

747

P202: Early Surgery Determines Motor Recovery in Lumbar Disc Patients with Associated Acute Radiculopathy

Nikolaus Kögl ¹ , Ondra Petr ¹ , Lukas Grassner ¹ , Ahn Khoa Vo ² , John Kramer ² , and Claudius Thomé ¹

¹ Medical University Innsbruck, Neurosurgery, Innsbruck, Austria

² University of British Columbia, International Collaboration on Repair Discoveries (ICORD), Vancouver, Canada

Introduction: Lumbar disk herniation (LDH) is the most common lumbar spine surgery. While cauda equina syndrome should be surgically addressed within 48 hours, little is known about the timing of disk surgery for acute radicular weakness, despite half of the patients undergoing surgery present with motor deficits. The aim of this study was to evaluate the impact of surgical timing on motor recovery in LDH patients and identify an ideal time window for intervention. Material and Methods: In a single-center study, 390 patients with LDH-associated motor deficits were prospectively followed for a minimum of 1 year after non-elective disk surgery. The duration of motor deficit prior to surgery was documented. The degree of motor weakness was assessed using both functional as well as manual testing and was categorized according to the Medical Research Council (MRC) scale. In order to determine reliable cut-off times for optimal surgical intervention, unbiased recursive partitioning conditional inference tree (URP-CTREE) was used for statistical analysis of motor recovery. Results: A preoperative motor deficit of MRC ≤ 2/5 (P < .001) and the duration of paresis were identified as the most important predictors of recovery. Surgery within 3 days was associated with a better recovery both for severe and moderate/mild deficits (P = .017). Early intervention significantly increases the chance of complete and faster recovery. Conclusion: Timing of surgery is decisive for motor recovery in LDH-associated deficits. Prompt diagnosis and referral should be aimed for to allow disk surgery within 3 days in patients with severe and moderate radicular weakness.

750

P203: Platelet-Rich Plasma Usage in Case of Lumbar Spine Stenosis. Is the Post-Operative Effect Worth Spending Intraoperative Time?

Mikhail Safronov ¹ , Anton Borzenkov ¹ , Soslan Torchinov ¹ , and Dmitry Dzukaev ¹

¹ City Clinical Hospital 67 n.a. L.A.Vorokhobov, Moscow Spine Center, Moscow, Russian Federation

Introduction: Platelet-Rich Plasma is widely used by the oral and maxilofacial surgeons to treat bone defects. It contains great concentration of different growth-factors that can stimulate tissue healing and bone consolidation and can also be much helpfull in cases of degenerative spinal stenosis. The objective is to compare the efficacy of autologous bone graft from resected bone structures and PRP with local bone graft alone for promotion of bony union in posterolateral lumbar fusion (PLF) surgery. Material and Methods: From August 2016 to June 2019 a group of patients with lumbar stenosis (40) was enrolled in this study. To investigate PRP effect on recovery rate in cases of some spinal diseases we have arranged 2 groups of patients with 2 or more level degenerative stenosis in the lumbar spine, and 2 groups with one-level degenerative lumbar spine stenosis. All those cases required the screws and one or two level fusion. All those patients were treated with the pedicle screws, discectomy and local bone grafting. There were patients with degenerative stenosis due to spondylolysis and disk herniation. The symptoms were evaluated by Visual analogue scale (VAS) score and Oswestry dysfunction index (ODI) a day before the surgery, 10 days after the surgery, 3 and 6 months after the surgery. We assessed the surgical outcome with the help of X-ray examination (flexion and extension view). We used the CTscans in 3 days after the surgery (or intraoperative), 3 months and 6 months after the surgery to assess the bone fusion. Results: Average bone fusion zone (judging by the CT-scans) on the level with bone graft and PRP was much wider comparing it to the level with bone graft alone. We have observed the fusion rate increase both at 3 and 6 months scans. VAS and ODI scores were also used. No adverse effects related to PRP usage occurred during this study. Conclusion: The mixing of PRP with the local bone graft can give the significant positive impact on bone fusion in case of lumbar spine fusion.

751

P204: Recurrent Lumbar Disk Herniation or Poorly Performed Surgery: The Definition If the Term "True Disk Reherniation", Predictors Analysis

Dmitry Dzukaev ¹ , Anton Borzenkov ¹ , Vladimir Guly ¹ , and Ivan Khutornoy ²

¹ City Clinical Hospital 67 n.a. L.A.Vorokhobov, Moscow Spine Center,, Moscow, Russian Federation

² High school of medicine Lomosov University, Moscow, Russian Federation

Introduction: the incidence of the second discectomy surgery in case of recurrent disk herniation varies from 10% to 15% of general number of initial surgeries, according to different authors. Almost a half of revision surgeries occurs in a year from the first surgery. It should be noted, that the reason of revision surgery is not always clear. Due to this factor, the reasons and indications for the revision surgery must be paid special attention. In this study, our aim was to formulate the concept of the true recurrent disk herniation; the purification of criteria and symptoms for true recurrent disk herniation; in practice research and verification of recurrent disk herniation criteria and building a predictive model on this basis Material and Methods: The research was held from 2014 to 2019. There were 525 patients analyzed, who underwent surgery at Moscow Spine Center. 292 patients had surgery at L4L5, where 29 patients had a reherniation. 233 patients had a surgery at L5S1, where 18 patients had a reherniation. We have studied predictors, defining the chance for recurrent disk herniation at the level L4L5S1: degeneracy grade proposed by Pfirrmann, Modic, type of the hernia, Grogan classification, range of motion (ROM), central lordosis angle (CLA), sex, age, BMI, Oswestry disability index, smoking, disk height index (DHI). Literary analysis was based on articles from PubMed, AOspine, Scholar.Google. Results: Using post evaluation, we have identified 4 main predictors which can define the chance for recurrent disk herniation at L4L5S1 authentically: disk height index (DHI), central lordosis angle (CLA), degeneracy grade proposed by Pfirrmann, type of hernia. Conclusion: You should tell the difference between the true recurrent disk herniation and badly performed surgery. The true recurrent disk herniation is the appearance of the herniation on the same side, on the same level, in case of hernia resection proven by postoperative MRI. If the patient has an MRI during early post-operative period lets us differentiate the recurrent disk herniation and badly performed surgery. Stabilizing this level will let us significantly drop the number of recurrent disk herniation in case of prevailing risk factors. In particular, the revealing high reherniation risk is the indication for detailed curettage, using stabilization systems.

774

P205: Hip Spine Syndrome—A Short Case Series at an Academic Hospital

Aftab Younus ¹ , Adrian Kelly ² , and Mohammad Hamza Aftab ³

¹ University of Witwatersrand, Department of Orthopaedic, Johannesburg, South Africa

² Sefako Makgatho Health Sciences University, Department of Neurosurgery, Pretoria, South Africa

³ University of Witwatersrand, Chris Hani Baragwanth Hospital, Johannesburg, South Africa

Introduction: Hip spine syndrome refers to the clinicopathological association between osteoarthritis of the hip and lumbar spine pain. The term was first described by Offierski and MacNab, almost 4-decades ago, in a retrospective study that described 35 patients with combined symptomatic osteoarthritis of the hip and lower back pain. Simple (primary) hip spine syndrome refers to patients with pathology in both areas, however clinically differentiating only one as the cause of pain is straight-forward. Secondary hip spine syndrome refers a patient in which both areas are symptomatic, however pathology in the one is recognized to have resulted in pathology in the other. Complex hip spine syndrome is used to refer to a patient with symptomatic pathology in both areas where clinical examination is unable to clearly identify which is the source of pain. These patients commonly undergo diagnostic caudal blocks, nerve root blocks, and hip joints injections, as adjunctive interventions to assist in determining the source of their pain. We report a series of 26 patients who presented to our unit with hip spine syndrome and through detailed history taking, and a specific set of clinical tests, we were able to determine which was the source of pain and which was secondary. Our subsequent surgical management, resulted in significant resolution of pain, with all these patients demonstrating a favorable outcome. Material and Methods: We presented 26 patients (N=26) with Hip and spine problems at the same time during 2013 to 2019. All of them initially presented with pain in the hip and spine at the same time. In 8 patient the groin pain was more than the lumber spine. Four of patients had previous spinal fusion operation. It was difficult to identify the source of pain, therefore caudal block and facet joint block was done. In 15 patient patients the pain improve with the block and 11 patients has to go for intra-articular injection in the hip and trochantic bursa of the hip. N = 18 patient had THR and N = 4 need further spinal surgery. Results: All of the patient was treated with conservatively initially and N = 18 had total hip replacement and N = 4 patients need posterior decompression and spinal fusion. Only N = 4 patients were happy with conservative treatment. The Harris hip score and SF 36 Scoring system, Oswestry disability index was calculated. These score have favorable outcome with our treatment. All of our patients were satisfied with our treatment. Conclusion: While hip spine syndrome was described almost 4-decades ago, the ongoing trend to compartmentalize the surgical disciplines into what we for example now-day term, orthopedic surgeon super-specialty arthroplasty, and neurosurgeon super-specialty spine, has resulted in hip spine syndrome being under-diagnosed. Our case series serves to highlight the association between osteoarthritis of the hip and degenerative lumbar stenosis, to both spinal neurosurgeons and arthroplasty orthopedic surgeons, to remind them that patients with hip spine syndrome comprise not only a well-defined specific patient sub-set.

781

P206: Patient Acceptable Symptom State for the Oswestry Disability Index Following Lumbar Fusion for Degenerative Spondylolisthesis

Graham Goh ¹ and Reuben Soh ¹

¹ Singapore General Hospital, Singapore, Singapore

Introduction: The patient acceptable symptom state (PASS) is a valuable tool for interpreting patient-reported outcomes (PROs) in orthopaedic research. Previous studies have attempted to define the PASS in a heterogenous cohort with different lumbar spinal disorders and surgical procedures. This study aimed to define PASS thresholds for the Oswestry Disability Index (ODI) specifically for patients undergoing lumbar fusion for spondylolisthesis-associated functional disability. Materials and Methods: Patients who underwent primary single-level minimally invasive transforaminal lumbar interbody fusion (TLIF) for degenerative spondylolisthesis between 2006 and 2014 were identified from an institutional spine registry. The ODI was collected preoperatively, 6 months and 2 years postoperatively. Responses to an anchor question adapted from the North American Spine Society (NASS) questionnaire were dichotomized and used as external criterion in receiver operating characteristic (ROC) curve analyses to define PASS thresholds. Sensitivity analyses were performed for different subgroups, baseline ODI tertiles, duration of follow-up, and an alternative definition of PASS. Results: In total, 529 (76%) patients completed 2-year follow-up, of which, 89% considered their symptom state to be acceptable. Areas under the curve (AUC) were .81-.90 for all ROC analyses, indicating that the ODI had an excellent discriminative ability to determine if a satisfactory state was achieved. The PASS threshold was ≤18.09 at 6 months (AUC .81, sensitivity 77%, specificity 72%) and ≤15.27 at 2 years (AUC .86, sensitivity 79%, specificity 79%). Sensitivity analyses revealed that the 15.27-point threshold was robust. After adjusting for age, gender, BMI, comorbidities and baseline ODI, PASS responders were 18 times more likely to be satisfied (OR 18.47, 95% CI 8.81-38.71) and 12 times more likely to have expectations fulfilled (OR 11.93, 95% CI 6.51-21.88) compared to non-responders. Conclusion: Patients with an ODI of ≤15.27 can be deemed to have achieved a PASS after lumbar fusion for degenerative spondylolisthesis. These findings will help surgeons to contextualize a patient’s functional recovery after lumbar spine surgery and enable researchers to define clinically relevant benchmarks when designing trials utilizing the ODI.

1099

P207: Are Lumbar Fusion Guidelines Followed? A Survey of North American Spine Surgeons

Thiago Montenegro ¹ , Christopher Elia ¹ , Kevin Hines ¹ , and James Harrop ¹

¹ Thomas Jefferson University, Neurosurgery, Philadelphia, USA

Introduction: This study aims to evaluate and gain insight into the use of guidelines for indications of lumbar spine fusions among spine surgeons in North America. Material and Methods: An anonymous survey was electronically sent to all A.O. Spine North America (AOSNA) members. Questions of the survey consisted of demographic as well as 18 clinical vignettes to elucidate participating surgeons’ indications for lumbar spine fusion. The spine surgeons were asked whether they would include a lumbar spine fusion in the treatment of these selected patients. Each survey’s questions intended to evaluate one of the NASS guideline indications for lumbar spinal fusion. Participants were asked if they included the NASS guidelines in their decision-making algorithm. Fusion indications in accordance with NASS guidelines, were considered NASS-concordant answers. The participating surgeon was considered to have a NASS-concordant approach if ≥70% (13/18) of their answers were NASS-concordant answers. Comparisons between the answers were conducted using a chi-square test, Fisher’s exact test, the unpaired 2-tailed Student’s t-test, and the Mann-Whitney U-tests as appropriate based on frequency table cell counts, and assumptions of normality. A p-value < .05 was set for statistical significance. Results: A total of 105 responses were entered with complete data available on 70 (11.4%). 91% (n = 64) of the participants practice in the USA (U.S). The majority of the responses were from Orthopedic Surgeons (n = 49; 70 %), and 68 participants (97.1%) have fellowship training. The majority of the spine surgeons (n = 42; 60%) stated following the EBM NASS guidelines when selecting lumbar fusion indication. The number of NASS-discordant answers were not statistically different between Neurosurgeons (4.62 ± 1.85) and the Orthopedic surgeons (5.06 ± 2.07) (P = .403), neither between the group who stated that they included the NASS guidelines in their decision-making algorithm (5.10 ± 1.96) and the group who do not include it (4.68 ± 2.09) (P = .395). The greatest number of NASS-discordant answers in the U.S. was in the South (5.75 ± 2.09), while the lowest number in the Northeast (3.84 ± 1.70) (P < .01). Five items of the survey had an average of NASS-discordant answers ≥ 40%. The greatest number of NASS-discordant responses was the indication of fusion in cases of deformity (80%). Spine surgeons utilizing a NASS concordant approach had a significant lower number of NASS-disconcordant answers for synovial cysts (P = .03), axial LBP (P < .01), adjacent level disease (P < .01), recurrent stenosis (P < .01), recurrent disc herniation (P = .01), and foraminal stenosis (P < .01). Conclusion: The majority of AOSNA members followed the NASS criteria in their decision-making algorithm. Overall, experience, training, specialty did not affect decision making. However, geographical differences were seen in survey results. Specific survey items had a great average of NASS-discordant answers, while NASS criteria was met more frequently by surgeons utilizing a NASS concordant approach for another group of pathologies. These pathologies may serve as starting points for further investigation of outcomes associated with NASS criteria and the usefulness of its implementation.

1121

P208: Acute Bilateral Foot Drop with Radiculopathy: A 'New' Aetiology not to Forget

Marco Mancuso-Marcello ¹ , Asfand Baig Mirza ² , Joseph Frantzias ³ , Richard W Gullan ² , and Andreas Demetriades ¹

¹ Royal Infirmary of Edinburgh, Department of Clinical Neuroscience, Edinburgh, United Kingdom

² King's College Hospital, Department of Neurosurgery, London, United Kingdom

³ Royal County Sussex Hospital, Department of Neurosurgery, Brighton, United Kingdom

Introduction: Isolated acute bilateral foot drop due to degenerative spine disease is an extremely rare neurosurgical presentation, while the literature is rich with accounts of chronic bilateral foot drop occurring as a sequela of systemic illnesses. We present, to our knowledge, the largest case series of acute bilateral foot drop, with trauma and relevant systemic illness excluded as causes. Material and Methods: Data from 7 patients from 3 different centres had been collected at the time of historic treatment, and records were recently retrospectively reviewed, documenting the clinical presentation; radiological level of compression; timing of surgery; and degree of neurological recovery. Results: The mean age at presentation was 47.2 years (range 41-57). All but one patient were male. All 7 had a radiculopathic presentation and 3/7 had concomitant cauda equina syndrome (CES). The levels of compression in the first 2 cases with both bilateral foot drop and CES was L2/3 and L5/S1 whilst the final patient had an acute disc prolapse at L2-3 with concurrent canal stenosis at L4/5. The first two made a full motor recovery, the first one by 6 week follow-up and the second on same-day post-op evaluation. The final patient had mildly improved from 0/5 bilateral dorsiflexion to 1/5 at 2 weeks follow-up. Four cases had isolated pure bilateral foot drop. In three of these four cases, patients had a L3/4 posterolateral disc prolapse. The fourth one had one at L4/5. Of those with a prolapse at L3/4, two had only minor improvements in ankle dorsiflexion whilst the third patient had total resolution of symptoms at 1 year. The patient with the L4/5 prolapse had moderately improved at 8-month follow-up. Conclusion: The majority of cases, in albeit a small series of six, involved degenerative disc disease at L3/4. However, involved levels have ranged from L2/3 to L5/S1, which was rather surprising. Aberrant innervation may be at play. It is interesting that three out of the seven cases reported had concomitant cauda equina syndrome. This is not a surprise, as central stenosis and compression of the nerve roots on either side anatomically makes sense. The fact that the remainder had bilateral nerve root stenosis but no central disc prolapse is puzzling.

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P209: Changes in Segmental Lordosis at L5-S1 Following Placement of Anterior TLIF Cages

Timothy OConnor ¹ , Jennifer Mao ^1,2 , Elena Pezzino ¹ , Alex Hollenberg ¹ , Alexander Fritz ¹ , Justice Agyei ¹ , Mary O'Hehir ¹ , Brandon Mariotti ¹ , Jeffrey Mullin ¹ , and John Pollina ¹

¹ University at Buffalo Neurosurgery, Spine and Skull Base Disorders Team, Williamsville, NY, USA

² Rothman Orthopaedic Institute, Spine, Philadelphia, PA, USA

Introduction: Maintaining or restoring lumbar lordosis has become an integral aspect of treating degenerative spine disease and underlying spinal deformity. In an effort to increase the segmental lordosis of transforaminal lumbar interbody fusion (TLIF) procedures, the anterior TLIF cage is a relatively newer device that was developed to be placed at the anterior most portion of the vertebral body using a rotating inserter. The lumbosacral junction provides a significant contribution to the overall lordosis and sagittal vertical axis of the spine, and L5-S1 interbodies are commonly placed in long thoracolumbar constructs to aid in fusion. Material and Methods: We aimed to quantify the segmental lordosis we were achieving with anterior TLIF cages at L5-S1 and compare that to the segmental lordosis achieved with anterior lumbar interbody fusions (ALIFs) at L5-S1.We performed a retrospective chart review between 2018 and 2019 identifying anterior TLIF procedures as well ALIF procedures performed at L5-S1 from 2018 to 2019. Two independent researchers subsequently measured and validated segmental lordosis at L5-S1 both preoperatively and postoperatively. Data analysis was done using PRISM 8 statistical tool. A t-test analysis compared change in segmental lordosis of nine consecutive ALIF patients with nine anterior TLIF patients. Results: The average increase in segmental lordosis with ALIF patients was 6.5 degrees, and the average increase in segmental lordosis with anterior TLIFs was .8 degrees. This resulted in a significant increase in segmental lordosis with ALIF procedures compared to anterior TLIF procedures (P = .0168) (Table 1 & Figure 1). Nearly half of patients that underwent anterior TLIFs demonstrated a postoperative decrease in segmental lordosis, while all ALIF patients demonstrated a postoperative increase in segmental lordosis. Conclusion: In our series, ALIFs provided significantly increased segmental lordosis compared with anterior TLIF procedures at L5-S1.

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P210: Are Internet Sites Providing Good Quality Information for Patients with Sciatica?

Marco Mancuso-Marcello ¹ and Andreas Demetriades ¹

¹ Royal Infirmary of Edinburgh, Department of Clinical Neuroscience, Edinburgh, United Kingdom

Introduction: Sciatica is a common neurological condition and a wide variety of clinical specialists and allied health professionals are involved in its management, with a broad range of treatment options. Patients suffering from sciatica who seek medical information on the internet can therefore find the task rather daunting and overwhelming. Material and Methods: The first three pages of links to websites on Google were assessed using the DISCERN instrument. This is a validated questionnaire, for both health consumers and providers, which assesses the quality of the information provided on internet sites dealing with medical conditions and their treatment options. Results: After relevant exclusions, 23 websites were assessed. Only 35% of sites had clear aims and objectives, whereas only 65% provided relevant information on sciatica. While 87% did not provide clear sources of their information with any bibliography, 65% had no indication of when the information was even compiled or updated. Only 43% of sites made it clear that more than one treatment option was available, and only 35% described in moderate to extensive detail how the various treatment modalities might work, with only 22% informing patients of potential risks and complications for each treatment. Those websites which were biased and/or unbalanced amounted to 44%, offering greater detail about one treatment modality over others. 26% were from commercial enterprises and 22% advocated a particular treatment. No website (0%) provided extensive detail about the side-effect profile of each treatment. Overall, 96% of assessed websites did not inform patients of the consequences/natural history if no treatment were undertaken; and 92% did not describe the potential impact of treatment and how it could affect quality of life. 43% advised readers to consult doctors, family, fellow sufferers, and support groups to enable shared decision-making, whereas only 13% of sites provided additional sources of further information or support. Conclusion: Even though the internet plays an important part of everyday life in modern society, the quality of information on the treatment of sciatica is of variable quality. Serious shortcomings were found in over 50% of all assessed websites; and 61% of sites assessed using the DISCERN instrument were of low-to-moderate overall quality. Healthcare providers should be aware of the risks of misinformation and take measures to guide, advise and reassure patients effectively. Creators of health-related internet websites ought to be aware of such pitfalls and be guided by instruments such as DISCERN.

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P211: Functional Comparison Outcome of Epidural Steroid Injection in Different Levels of Disc Herniation

Balamurugan Thirugnanam ¹ , Ajay Kumar Shetty Papanna ¹ , and Vidyadhara Srinivasa ¹

¹ Manipal Hospitals, Bengaluru, India

Introduction: Low back pain is one of the most common complaints for which patients seek medical attention. Radiculopathy is a common symptom and occurs in approximately 40% of adult population with herniated disc. However, all patients with radiculopathy does not show imaging features of disc prolapse, other factors such local inflammatory reactions in epidural space play an important role. Steroids reduce the inflammatory response induced by chemical, immunologic and mechanical lesions. Hence local delivery of steroids into the epidural space gives a concentrated dose which will cause an effect that lasts longer. Therefore, this study was done to study the functional outcome comparison of Epidural Steroid Injection (ESI) in different levels of lumbar disc herniation (LDH). Material and Methods: A hospital based prospective study was conducted in 1000 consecutive patients [group A (L3-L4 level): 112 patients, group B (L4-L5 level): 484 patients, group C (L5-S1 level): 316 patients, and group D (Multi-level): 88 patients] from January to August 2018. All patients were given epidural injection prepared with Triamcinolone (80mg), Bupivacaine (.25% 4ml) and normal saline (4 ml). Patients were evaluated using numerical rating scale (NRS) immediately, 7 days and 3 months after the injection. Results: The average age of the study population was 41.8 (range: 20-80) years. Males were found to be more in all the groups. Mean NRS back pain scores and leg pain scores reduced significantly in all groups, more in group B than others. We found that in group A, B, C, and D patients, 22 (19.65 %), 44 (9.09%), 54 (17.08%), and 34 (38.63 %) respectively underwent surgery. Hence there was significant satisfactory outcome in the groups with B (90.9%) >C (82.99%)> A (80.35%) >D (61.36%). Conclusion: ESI causes statistically significant improvement in back and leg pains in patients with any level of disc herniation, more so in L4-L5 level. However, the short and medium term efficacy of ESI in multilevel disc herniation group was lesser than that of single level disc herniation groups.

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P212: Dural Tear Does Not Increase the Rate of Venous Thromboembolic Disease in Patients Undergoing Elective Lumbar Decompression with Instrumented Fusion

David Love ¹ , Jael Camacho ¹ , Jacob Bruckner ¹ , Alex Pu ¹ , Navid Chowdhury ¹ , Daniel Cavanaugh ¹ , Eugene Koh ¹ , Daniel Gelb ¹ , and Steven Ludwig ¹

¹ University of Maryland School of Medicine, Department of Orthopaedics, Baltimore, USA

Introduction: To evaluate dural tear as a risk factor for venous thromboembolic disease in patients undergoing elective lumbar decompression and instrumented fusion as well as evaluate other risks associated with sustaining a dural tear. Current data is contradictory regarding whether sustaining a dural tear increases the risk for venous thromboembolic disease. Material and Methods: A retrospective cohort of patients undergoing elective lumbar decompression and instrumented fusion at a single academic, between 2016 and 2019 was identified. Medical records were reviewed for patient demographics, intraoperative characteristics, postoperative management, and postoperative outcomes. Dural tear and non-dural tear cohorts were compared, with continuous variables analyzed via t-test or Wilcoxon rank-sum, and nominal variables via Fisher’s exact or chi-squared test. Results: 611 patients met inclusion criteria. 144 patients (23.6%) sustained a dural tear (DT), with no difference between primary and revision surgery (21.5 vs 26.8%, P = .14). The DT and non-DT cohorts were similar demographically, with the exception that the DT cohort tended to be older (63.6 vs 60.6 years, P = .0052) and have more comorbidities (CCI 2.75 vs 2.35, P = .0056). The majority of DT patients were managed with 24 hours (50.0%) or over 24 hours (36.6%) of flat bedrest. There was no significant difference in the rate of DVT (2.1 vs 2.6%, P = 1.0) or PE (1.4 vs 1.50%, P = 1.0). Intraoperatively, DT was associated with increased EBL (754 vs 512 mL, P < .0001), increased operative time (224 vs 195 minutes, P < .0001), and increased rate of transfusion (19.4 vs 9.4%, P = .0018). Postoperatively, DT was associated with increased time to ambulation (2.6 vs 1.4 days, P < .0001), increased length of stay (5.8 vs 4.0 days, P < .0001), higher total incidence of in-hospital complications (55.6 vs 32.2%, P < .0001), and an increased rate of discharge to rehab (38.9 vs 25.3%, P = .0021). Conclusion: Sustaining a dural tear during elective lumbar decompression and instrumented fusion does not significantly increase the rate of venous thromboembolic disease. Dural tear is correlated with increased EBL, operative time, need for transfusion, a higher overall incidence of complications, and a decreased rate of discharge to home, as well as leads to increased time to ambulation and increased length of stay.

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P213: Epidural Steroid Injection in Lumbar Disc Herniation and Lumbar Canal Stenosis: Is It Just A Placebo?

Balamurugan Thirugnanam ¹ , Ajay Kumar Shetty Papanna ¹ , and Vidyadhara Srinivasa ¹

¹ Manipal Hospitals, Spine Care, Bengaluru, India

Introduction: Low back pain is one of the most common complaints for which patients seek medical attention. Radiculopathy is a common symptom and occurs in approximately 40% of adult population with herniated disc. However, all patients with radiculopathy does not show imaging features of disc prolapse, other factors such local inflammatory reactions in epidural space play an important role. Steroids reduce the inflammatory response induced by chemical, immunologic and mechanical lesions. Hence local delivery of steroids into the epidural space gives a concentrated dose which will cause an effect that lasts longer. Therefore, this study was done to study the role of Epidural steroid Injection (ESI) in patients with herniated disc and Lumbar Canal Stenosis (LCS). Material and Methods: A prospective cohort study on the functional outcome of patients with low back pain and with or without leg pain proven to have herniated disc or LCS. Outcome measures used in this study was numerical rating scale (NRS). After initial assessment, selected patients were given Epidural injection of Triamcinolone and local anesthetic Bupivacaine. Patients were evaluated immediately, 7 days and 3 months after the injection was given. Results: A total of 1000 patients out of which 645 patients have herniated disc and 355 patients have LCS were given ESI in the study period i.e. January 2018 to August 2018. All 1000 patients were included in the study as per the inclusion and exclusion criteria. Patients between 20 and 80 years of age were included. Median pre-injection NRS scores of herniated disc group were 5 (4-8) for back pain and 5 (4-9) for leg pain, immediately after injection 4 (2-7) for back pain and 3 (3-7) for leg pain, after 7 days 2 (1-7) for back pain and 1 (1-6) for leg pain, after 3 months 2 (1-7) for back pain and 2 (1-7) for leg pain with a p value of <.001. Median pre-injection NRS scores of LCS group were 5 (4-8) for back pain and 5 (4-9) for leg pain, immediately after injection 4 (2-7) for back pain and 4 (3-7) for leg pain, after 7 days 2 (1-7) for back pain and 2 (1-6) for leg pain, after 3 months 3 (1-7) for back pain and 3 (1-7) for leg pain with a P value of <.001. Conclusion: We conclude that there is a significant symptomatic improvement both clinically and statistically in patients with herniated disc after ESIs. The outcome in the LCS group was not satisfactory.

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P214: Early Experience of Lateral Position Anterior Lumbar Inter Body Fusion

Zacharia Silk ¹ , Peter Loughenbury ¹ , Andrew Berg ¹ , Almas Khan ¹ , Nigel Gummerson ¹ , Greg Rudol ¹ , Debasish Pal ¹ , and Jake Timothy ¹

¹ Leeds General Infirmary, Leeds Centre for Neurosciences, Leeds, United Kingdom

Introduction: Anterior lumbar interbody fusion (ALIF) is often used at L5/S1. Traditional ALIF is performed in the supine position. A novel lateral-access retractor system now makes it possible to perform an ALIF in the lateral decubitus position. Benefits include improved access and the option of single position surgery. We present our early results using this system to perform L5/S1 ALIF in the lateral position. Methods: Analysis of prospectively collected outcomes data entered into the British Spine Registry. Surgery performed as two-surgeon procedures (6 surgeons included). All cases performed in the lateral decubitus position using a novel retractor system and instrumentation. Results: Total of 15 patients (9 male), mean age 46 years (range 32-61). All cases were at L5/S1 with 14 isolated primary single level fusions and one revision as part of a long lumbar fusion construct. In 14 cases, a 360-degree fusion was achieved with a posterolateral fusion (8 minimally invasive; 6 open) either as a staged procedure (8 cases) or at the same sitting (6 cases). Median follow up of 12 months (8 cases) demonstrated improvements in ODI score (52 vs 24), EQ5D (49 vs 64), VAS back pain score (6.7 vs 2.7) and VAS leg pain score (7.7 vs 2.5). Median length of stay 4 days (range 1-20). No early complications relating to anterior surgery reported. Conclusion: Early experience of performing an ALIF in the lateral position indicate that the procedure is safe and effective. Ongoing surveillance will allow evaluation of the technique.

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P215: Does the Cost Related to Peri & Post -Operative Outcome Factors Among Single Stage, One and Two Level Surgeries Influence Decision Making on Which Inter-Body Fusion to Employ? Comparative Analysis

Solanga Arachchilage Chanaka Solangaarachchi ¹ , Craig James Sheridan ¹ , and Sahadu Saajid Kaleel ¹

¹ Ipswich Hospital, Spinal Surgery, Ipswich, United Kingdom

Introduction: Surgical interbody fusion in the setting of degenerative lumbar pathologies is an effective treatment through stabilisation of the painful motion segment, indirect decompression of neural elements, restoration of lordosis and deformity correction. Established surgical approaches include PLIF, ALIF, TLIF, OLIF/LLIF. There is no clear consensus amongst the spinal community over which surgical approach confers best patient outcomes. Operative choice is determined by relative indications and contraindications based on intended surgical level and anatomical relations, which affect operative risks, time and clinical and radiological outcomes. Healthcare economics are a necessary consideration for institutions. There are detailed analysis of surgical costs of different interbody fusions, however, there are no recent studies that focus on the additional costs related to follow-up for the different surgical approaches. Purpose of this study is to analyse the additional costs associated with interbody fusion and to determine if there is any difference in the following: duration of hospital stay, number of out-patient follow-up consultations, requirement for unplanned post-operative imaging, acute admissions and additional procedures were measured a 1 year post-operative period. Material and Methods: Retrospective review of single unit’s data were retrieved from databases for all single or two level interbody fusions carried out between 1st January 2017 to 31st December 2018. One year of follow up data was collected. Univariate analysis was performed to describe the cost related outcome measures in interbody fusion type and extract the patterns with in it. Multivariate analysis of each cost related outcomes measure among three interbody fusion surgeries (ALIF, TLIF, LLIF) was performed to identify any statistically significant differences in follow-up costs. Results: Eight LLIFs, 44 TLIFs and 47 ALIFs single stage one or two level interbody fusions procedures were performed during this period. The main indications for surgery were lytic spondylolisthesis (n = 33), recurrent disc/stenosis with radiculopathy (n = 29), degenerative spondylolisthesis (n=14), discogenic back pain (n = 11), foraminal stenosis (n = 9). One-way analysis of variance (ANOVA) found only length of hospital stay to be statistically significantly different between the three interbody groups (F(2,96) =4.611, P = .012). Post hoc analysis showed significantly higher hospital stay in ALIFs (‾x=2.68) compared to TLIFs(‾x=1.98) and XLIFs(‾x=1.50). All other cost-related outcome factors in the first post-operative year were not statistically significantly different. This included number of spine clinic follow-up appointments (F(2,96) =2.824, P = .064), number of follow-ups appointments from other specialties (F(2,96) = .665, P = .517), number of emergency department attendances (F(2,96) = .252, P = .777), ward readmissions related to surgery (F(2,96) = .287, P = .751), number of injections to control residual pain (F(2,96) = .618, P = .541), number of surgeries to address complications (F(2,96) = .139, P = .870), number of follow-up lumbar X-rays (F(2,96) = .227, P = .797), Computer tomography scans (F(2,96) =1.493, P = .230)and Magnetic resonance imaging scans (F(2,96) = .503, P = .606) failed to demonstrate statistically significant difference between ALIFs, TLIFs and LLIFs. Conclusion: Length of hospital stay was noticeably longer in ALIF compared to LLIF and TLIF. In all other respects, non-implant costs were not significantly different during the peri and post-operative period. These factors should not influence surgical decision making when deciding which Interbody Fusion to employ.

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P216: Skeletal Fluorosis: A Rare Cause of Spinal Cord Compression

Khalil Habboubi ¹ , hassen makhlouf ¹ , Chaker Mohamed ¹ , Ayadi Boubaker ¹ , lanouar Bouzid ¹ , and Mondher Mestiri ¹

¹ Kassab institute, Tunis, Tunisia

Introduction: Fluorine is a trace element. In certain circumstances, excessive quantities of fluorine may accumulate in the body, particularly in the bones. Skeletal fluorosis is characterized mostly by bone and dental changes with later ossification of many ligaments and interosseous membranes. Neurological complications are rare. They consist of nerve root or spinal cord compression by bony excrescences. We report a case of spinal cord compression at the thoracic level in a patient with previously unknown bone fluorosis. Case Presentation: A 50-year-old man from a rural area presented to our orthopedic department after a moderate trauma a week ago. He had a monoplegia of the right lower limb and urinary incontinence. Physical examination showed brownish discoloration of the teeth and marked pyramidal signs in the right lower limb. Radiograph of the thoracic and lumbar spine found a moderate diffuse vertebral sclerosis. Magnetic resonance imaging (MRI) was performed in the emergency room to assess neurological impairment. It disclosed compression of the dorsal spine cord at T8, T9 and T10 level with a low T1 and T2 process originating from the posterior arch of the vertebra. Computed tomography (CT) was performed to assess this posterior spinal abnormality and showed ossification of the yellow ligament. Fluoride poisoning was suspected based on the geographic origin of the patient, brownish discoloration of the teeth, and imaging findings. Fluoride assays showed marked elevation in urine, confirming our diagnosis. Surgical treatment was indicated, and the patient had a multilevel decompression by laminectomy at the dorsal spine. After two months of physical reeducation, our patient presented significant neurological impairments recovery. Conclusion: The outcome of patients with spinal cord compression due to fluorosis depends on the extent of the lesions and duration of poisoning. Diagnostic delay and prolonged fluoride exposure are associated with poor outcomes. CT and MRI of the spine allow an early diagnosis and an accurate assessment of neurological complications. Early Surgery is mandatory in patients with spinal cord compression. Prevention is the best possible approach to tackle fluorosis, since no cure at present is possible once disease sets in.

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P217: Minimally Invasive Versus Open Surgery for Degenerative Conditions - Systematic Review

Rodrigo Amaral ¹ , Gabriel Porkony ¹ , Rafael Moriguchi ¹ , and Luiz Pimenta ¹

¹ Instituto de Patologia da Coluna, São Paulo, Brazil

Introduction: There is still debate regarding the capabilities of minimally invasive surgery (MIS) to compete or overthrown the open surgery techniques for degenerative conditions of the lumbar spine, due to the steep learning curve of some MIS techniques and the costs of the surgery materials. However, in the last years, with the technology leap that overpowered several industrial areas, MIS techniques gained essential implements such as navigation surgery, neuromonitorization, and new surgery tools. The objective of our work was to compare the results of both open and MIS surgeries regarding degenerative conditions. Methods: We performed a review of the literature with the following research strategy “(((((Minimally invasive) AND Open) AND Spine Surgery) AND Degenerative)) AND Lumbar)” at PubMed; OVID and BVS Salud databases. The inclusion criteria were: Articles regarding degenerative conditions and Articles comparing minimally invasive and open techniques. The exclusion criteria were: Congress abstracts, Reviews; Articles in other languages than English or Portuguese, Articles that contained any of the outcomes of interest. The outcomes of interest were: Blood loss, Surgery duration, ODI or SF-36, Number of complications and Surgery value. The meta-analysis was realized with a standard mean difference for continuous variables and Odds ratio for dichotomous data. If the heterogeneity the included studies were too heterogeneous the random-effect model was applied, for the other cases the Fixed-effect model. A value of P < .05 was considered significant. Results: 64 articles were included in the review. 27 had enough data to analyze the surgery time duration revealing that there was no significant difference between the groups (SMD .28; 95% CI; -.43 to .99; P > .05), as for the blood loss 25 articles were analyzed showing that MIS surgery had significantly less blood loss (SMD 2.00; 95% CI; .49 a 3.50; P = .003), the patients in the MIS group also had smaller length of stay (SMD 1.17; 95% CI; .66 a 1.8; P < .001). Patients undergoing MIS techniques had lower postop (SMD .72; 95% CI; -.01 a 1.45; P < .05) and Last FUP (SMD .23; 95% CI; .02 a .45; P = .02). There were fewer complication in MIS surgery compared to the Open group (OR .62; 95% CI; .49 a .79; P < .001). Also, five articles compared the value of MIS and Open surgeries in our meta-analysis there were no differences between the costs of the techniques (SMD .23; 95% CI; -4.91 a 1.85; P > .05). Conclusion: Our meta-analysis revealed that MIS surgery was superior to the Open surgeries regarding degenerative spine conditions at reducing blood loss, reducing complications, and improvement of ODI.

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P218: Change in QOL Metrics After Lumbar Spine Surgery in the Elderly

Mitchell Hansen ¹ and Yumi Kashida ²

¹ Newcastle Private Hospital, Neurosurgery, Newcastle, Australia

² Newcastle Brain & Spine, Newcastle, Australia

Introduction: Lower back pain decreases physical functions and Quality of Life (QOL) in the elderly population. Aim: We aim to describe the change in QOL metrics after lumbar spine surgery among elderly patients (75 years and over) suffering lumbar degenerative diseases. Methods: We retrospectively reviewed the data collected from 2013 to 2019. We included patients if they; 1) were aged 75 years and over at surgery, 2) underwent lumbar spine surgery due to degenerative disease, and 3) had baseline scores of EuroQOL 5D-3L (EQ-5D), Oswestry Disability Index (ODI) and Roland Morris Disability Questionnaire (RDQ). We analysed the short-term (6 weeks after surgery) and long-term (> 6 months) postoperative change in those QOL metrics. Results: We included 105 patients. Of these, 75 patients had short-term outcomes, and 70 had long-term outcomes. The mean improvement in EQ-5D was .25 ([95%CI .19-.32], P < .001) in the short-term, and .19 ([95%CI .11, .27], P < .001) in the long-term. ODI and RDQ also improved significantly; the mean ODI improvement was 15.1 (P < .001) in the short-term, and 14.1 (P < .001) in the long term, the RDQ improvement was 4.2 (P < .001) in the short-term and 4.4 (P < .001) in the long-term. Patients who underwent spine fusion surgery improved all metrics after surgery, although the improvement was not significant in the long-term (the mean EQ-5D improvement; .09, P = .3). Conclusion: In this study, QOL metrics among elderly patients improved after lumbar spine surgery. Surgery may contribute to better lives for elderly people suffering from lower back pain.

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P219: Histological Differences in Ligamentum Flavum Between Degenerative Lumbar Canal Stenosis and Non-Stenotic Group. A Comparative Study

Mantu Jain ¹

¹ AIIMS Bhubaneswar, Orthopedics, Bhubaneswar, India

Objectives: To compare the histopathological changes in the ligamentum flavum (LF) between degenerative lumbar spinal stenosis (LSS) and the non-stenotic (non-LSS) group. Background: The LF is the prime culprit in the pathogenesis of LSS. LF, which is purely elastic, undergoes a morphological adaptation that includes a reduction in the elastic fibers with the consequent increase in the collagen, fibrosis, cicatrization, and calcification. However, details morphometric analysis can delineate the LF in patients with LSS from those of non-LSS, which would help in a deeper understanding of the pathogenesis of LSS. Methods: Eighty-two patients were prospectively recruited and divided into two groups: LSS and non-LSS. Their demographic details, including duration of symptoms, level, number of segments, were recorded. The ligament flava obtained from both groups was histopathologically examined for fibrosis score, elastic fibers degeneration, calcification, and chondroid metaplasia. Morphometrical details included a change in elastin fibre percentage, collagen fibre percentage, elastin/collagen ratio, elastic fiber fragmentation, and ligamentocyte numbers. All parameters were compared between the two groups using unpaired students test in SPSS version 21. Pearson’s correlation was assessed between various changes in regards to time in the stenotic group. Results: Out of 82 cases, 74 were analysed, 34 in LSS and 40 in non-LSS group. The mean ± SD age of presentation in LSS and non- LSS group was 49.2 ± 8.9 and 43.1 ± 14.3 respectively. The LSS group (n = 34) exhibited significant differences in fibrosis (P-value = .002), elastic fiber degeneration (P-value = .01), % elastic fragmentation (66.5 ± 16.3 vs 29.5 ± 16.9), % elastic, content (26.9 ± 6.7 vs 34.7 ± 8.4), % collagen content (63.6 ± 10.4 vs 54.9 ± 6.4), reduction of elastic/collagen (.4 ± .1 vs .6 ± .1), and ligamentocyte number (39.1 ± 19.1 vs 53.5 ± 26.9) as compared to non-LSS group (n = 40). The calcification (P-value = .08) and Pearson’s correlation between duration and loss of elastin was not significant. The difference in LF morphology is consistent in patient’s ≥40 years of age among the groups as found in subgroup analysis. Similarly in the patents <40 and >40 in the non-LSS group. Conclusions: Morphological analysis showed a quality change in elastin fibers and an increase in collagen content and fibrosis, which is responsible for the loss of elasticity of LF that contribute to the pathogenesis of LSS. Calcification as found by earlier authors was non-significant.

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P220: Anterior Versus Lateral Lumbar Fusion: A Comparison of Long-Term Outcomes in the Treatment of Degenerative Spinal Disorders

Daniel Coban ¹ , Stuart Changoor ¹ , Conor Dunn ¹ , Michael Pompliano ¹ , Kumar Sinha ¹ , Ki Hwang ¹ , Michael Faloon ¹ , and Arash Emami ¹

¹ St. Joseph's University Medical Center, Paterson, NJ, USA

Introduction: Lumbar spinal fusion is a common surgical procedure used to treat various degenerative spinal disorders. Extreme lateral interbody fusion (XLIF) and anterior lumbar interbody fusion (ALIF) have both been progressively utilized by spinal surgeons, offering advantages of reduced tissue trauma, blood loss, and improvements in post-operative patient reported outcomes. With the development of multiple techniques capable of addressing various forms of lumbar pathology, surgeons have been left with more than one option for patients whom these approaches may be applicable. Although the literature has reported a higher proportion of neurological complications in XLIF, the anterior approach has been associated with a larger overall complication proportion, including a greater number of vascular complications. However, there is a paucity of reports comparing the two approaches in the long-term. Therefore, the purpose of this study was to assess and compare the overall revision rates, perioperative complications and functional clinical outcomes with long-term follow-up in both ALIF and XLIF. Material and Methods: A retrospective review was performed to identify all patients between 2013 and 2018 who underwent ALIF or XLIF for degenerative lumbar spinal disorders with a minimum follow-up of 2 years. Demographic data was recorded and compared between both cohorts. Revision rates and time to revision in each group was compared. Perioperative complications were recorded. Functional outcomes were assessed with ODI and VAS measurements at follow-up visits. Standard binomial and categorical comparative analysis were performed. Results: A total of 293 patients were included, 178 in the ALIF cohort and 115 in the XLIF cohort. Mean follow-up for the XLIF and ALIF groups were 46.3 and 42.2 months, respectively. The overall revision rate was 7.8% for the XLIF group and 7.9% for the ALIF group (P = .990). The average time to revision was 270.1 ± 133.0 days and 301.1 ± 140.7 days for the ALIF and XLIF groups, respectively (P = .058). The most common reason for revision in each cohort was persistent radiculopathy in the ALIF group (57.1%) and symptomatic adjacent segmental disease in the XLIF group (44.4%). Three patients (1.7%) in the ALIF group required intraoperative repair of the common iliac vein due to incidental transection perioperatively whereas one patient (.9%) underwent repair of the dura due to incidental durotomy in the XLIF cohort (P = .557). Both cohorts experienced significant improvements in their functional outcomes scores compared to their pre-operative values. VAS scores decreased by a mean of 5.6 in the XLIF group and a mean of 2.5 in the ALIF group, a significant difference (P = <.001). Conclusion: Our two-year results suggest that XLIF and ALIF are reasonable alternatives for the treatment of lumbar spinal disease. After long-term follow-up, revision and complication rates did not differ significantly; however, the ALIF group had a larger number of complications which were all related to vascular injury. Additionally, the XLIF cohort had significantly greater VAS score improvement compared to the ALIF cohort. Both procedures offer advantages of reduced blood loss, tissue trauma and decreased hospital length of stay.

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P221: Clinical and Radiological Outcomes Between Anterior Lumbar Interbody Fusion with Percutaneous Pedicle Screw Fixation and Transforaminal Lumbar Interbody Fusion in the Treatment of High-Grade Isthmic Spondylolisthesis

Daniel Coban ¹ , Stuart Changoor ¹ , Conor Dunn ¹ , Michael Pompliano ¹ , Kumar Sinha ¹ , Ki Hwang ¹ , Michael Faloon ¹ , and Arash Emami ¹

¹ St. Joseph's University Medical Center, Paterson, NJ, USA

Introduction: Isthmic spondylolisthesis (IS) is a common spinal condition defined by anterior subluxation of the vertebral body due to a defect in the pars interarticularis. When conservative measures fail to alleviate symptoms, a number of surgical approaches including anterior lumbar interbody fusion with percutaneous pedicle screw fixation (ALIF with PPF) or transforaminal lumbar interbody fusion (TLIF) can be utilized to achieve fusion and address the defect. Treatment of low-grade spondylolisthesis utilizing these techniques have been well described in the literature; however, there is a paucity of reports comparing the long-term outcomes between ALIF with PPF and TLIF in the setting of high-grade IS. Therefore, the purpose of this study was to assess the overall revision rates, radiographic parameters and functional clinical outcomes of ALIF with PPF and TLIF in the treatment of high-grade IS. Material and Methods: A retrospective review was performed to identify all adult patients between 2009 and 2018 who underwent ALIF with PPF or TLIF for high-grade isthmic spondylolisthesis with a minimum follow-up of 2 years. Demographic data was recorded and compared between both cohorts. Revision rate and time to revision in each group was compared. Radiographic evaluations utilizing anteroposterior (AP) and lateral X-ray were analyzed. Functional outcomes were assessed with ODI and VAS measurements at follow-up visits. Standard binomial and categorical comparative analysis were performed. Results: A total of 65 patients were included, 35 in the ALIF with PPF cohort and 30 in the TLIF cohort. Mean follow-up for the TLIF and ALIF with PPF groups were 39.2 and 45.4 months, respectively. The overall revision rates were 10.0% and 11.4% for the TLIF and ALIF with PPF groups, respectively (P = .853). Two of four patients in the ALIF with PPF group were indicated for revision due to persistent radiculopathy, and the remaining two patients were indicated by pseudarthrosis. Two of three patients in the TLIF group were indicated for revision due to persistent radiculopathy, and the remaining patient was indicated by adjacent segmental disease. Average time to revision was 425.5 ± 426.1 days for the ALIF with PPF group and 203.0 ± 280.3 days for the TLIF group (P = .675). One patient in the TLIF group required a durotomy repair and one patient in the ALIF with PPF group required repair of the common iliac vein due to incidental transection. Each cohort achieved a similar proportion of PI-LL mismatch correction, 86% in the ALIF with PPF group and 83% in the TLIF group (P = .790). Both cohorts experienced significant improvements in their functional outcome scores compared to their pre-operative values; however, the magnitude of improvement was not statistically significant. Conclusion: Two-year follow-up results suggest that ALIF with PPF and TLIF are both reasonable alternatives for the treatment of high-grade isthmic spondylolisthesis in adult patients. After long-term follow-up, there were less revisions in the TLIF cohort, however the difference was not statistically significant. Both procedures demonstrated similar improvements in functional outcome scores and sagittal alignment. Larger, prospective comparative studies are required to corroborate these findings.

1548

P222: Is There a Role for Intra-Operative Cell Salvage (IOCS) in Single-Level Posterior Lumbar Interbody Fusion (PLIF) Surgery? A comparative analysis study

Riaz Mohammed ¹ , Roberto Carrasco ² , Shrijit Panikkar ¹ , Anant Tambe ¹ , Irfan Siddique ¹ , Saeed Mohammad ¹ , and Mahmoud Elmalky ^1,3

¹ Salford Royal NHS Foundation Trust, United Kingdom, Salford, United Kingdom

² The University of Manchester, United Kingdom, Salford, United Kingdom

³ Menoufia University, Faculty of Medicine, Shibin el Kom, Egypt

Introduction: Strategies for blood conservation in spinal surgery patients include various means adopted in the peri-operative period, including the use of intra-operative cell salvage (IoCS). Though IoCS has potential benefits in major spinal surgery including revision surgery, multilevel surgery, tumour surgery and deformity correction, the role of cell salvage in single level PLIF surgery is not well documented. The aim of this study is to understand the role of cell salvage in addressing blood conservation issues in single level PLIF surgery for lumbar degenerative disease. Methods: At a large tertiary spinal unit, single level PLIF procedures were performed in 190 patients from October 2012 to November 2018 of whom cell salvage blood was reinfused in 105 patients. Patients electronic records were accessed to collect demographic data, surgery related data, perioperative blood test results and blood transfusion data. Univariate and multivariate analyses were performed to determine independent predictors of drop in haemoglobin after the intervention. Results: IoCS was available for use in 112 patients (59%), of whom cell salvage blood was transfused back in 105 (93%) cases. Mean volume of blood transfused from cell saver was 284 ml (±184). Using the cell saver resulted in 36.79% blood recovery rate compared to the total estimated blood loss. Multivariable linear regression analysis for post-operative haemoglobin drop demonstrated that higher pre-operative haemoglobin level (P-value .001), male patients (P-value .002), younger age (P-value .032) and transfusion of IoCS blood (P-value .013) are significantly associated with lower drop in post- operative haemoglobin levels. Conclusion: IoCS in single level PLIF surgery needs to be considered in select cases on an individualised basis with our study showing that the patients who are of older age, female sex and lower pre-operative haemoglobin would benefit from intra-operative cell salvage.

1550

P223: Comparing Lumbar Spinal Fusion Perioperative Morbidity and Mortality by Approach Utilizing the National Inpatient Sample: 2005-2013

Conor Dunn ¹ , Stuart Changoor ¹ , Kumar Sinha ¹ , Ki Hwang ¹ , Michael Faloon ¹ , and Arash Emami ¹

¹ St. Joseph's University Medical Center, Paterson, NJ, USA

Introduction: Surgical fusion of the lumbar spine has become an increasingly popular treatment modality to address common pathologies of the spine. Furthermore, the past two decades have seen a significant change in the instrumentation and surgical approach decisions of the spine surgeon that has improved fusion rates and surgical outcomes. The advancement of lumbar fusion surgery, combined with an increasingly aging population, has led to a substantial surge in the number of procedures performed. The anterior (ALF), posterior (PLF) and combined anterior-posterior (APLF) approaches to addresses unique lumbar pathology have their own specific technical challenges and associated risks. The National Inpatient Sample (NIS) serves as the single largest all-payer inpatient database in the USA and provides weights for nationally representative estimates. For this reason, it serves as an appropriate approximation of the overall perioperative morbidity and mortality statistics for this and other procedures. Material and Methods: The NIS database was reviewed from 2005 to 2013. Patients undergoing elective lumbar fusion surgery were identified by their discharge ICD-9-CM code by approach with indications specific to the lumbar spine. Demographics of the study populations were assessed including age, gender, hospital region and teaching status, insurance status, race/ethnicity, median household income, total cost, length of stay and Charlson Comorbidity Index (CCI) score. Outcomes were assessed by frequencies of complications related to the procedure. Statistical analysis involved T tests, χ² analysis, and binary logistic regression with P < .001 denoting significance. Results: We identified 199,858 patients which represented an estimated 984,089 of weighted patients hospitalized for primary lumbar spine fusion. Patients undergoing ALF and APLF were significantly younger (54.3 ± 14.1, 53.9 ±13.6) than those that underwent PLF. The ALF cohort had significantly more DVTs and infections than the PLF cohort but less than the APLF cohort and significantly less PEs than both. The PLF cohort had significantly more durotomies and neurologic complications that the other two approaches but significantly less mortality. The APLF cohort had significantly more cardiac complications, hematomas, infections and DVTS than the other cohorts but significantly less dysphagia. Total charges were a median of 95,591 (range 2,445,376) with a length of stay median of 3.93 (range 1-254). Patients who died during hospital stay were significantly older (68.8 ±12.2), male (59.1%), utilized Medicare as their primary insurer (69.0%), had a higher CCI score (1.6), were more likely to be diabetics with complications (3.9%), have AIDS (2.5%), metastatic disease (1.5%), more than 2 chronic diseases (95.5%) and more total charges (185,536). On multivariate analysis, increased age, male sex and CCI were statistically significant independent predictors of mortality. Conclusion: Our study demonstrates that all lumbar spinal fusion approaches are increasingly common surgical techniques nationally in teaching and non-teaching hospitals with low rates of complications and overall mortality. The strongest predictor for mortality in these patients is those with more than 2 chronic diseases. We expect with the advancements in instrumentation that these procedures will continue to see an increase in utilization by the spinal surgeon across the country.

1569

P224: Perioperative Morbidity and Mortality of Posterior Lumbar Fusion: Analysis of the National Inpatient Sample from 2005 to 2013

Conor Dunn ¹ , Michael Faloon ¹ , Stuart Changoor ¹ , Kumar Sinha ¹ , Ki Hwang ¹ , and Arash Emami ¹

¹ St. Joseph's University Medical Center, Paterson, NJ, USA

Introduction: Surgical fusion of the lumbar spine has become an increasingly popular treatment modality to address common pathologies of the spine. Furthermore, the past two decades have seen a significant change in the instrumentation and surgical approach decisions of the spine surgeon that has improved fusion rates and surgical outcomes. The advancement of lumbar fusion surgery, combined with an increasingly aging population, has led to a substantial surge in the number of procedures performed. The posterior approach its associated with its own specific technical challenges and associated risks. The National Inpatient Sample (NIS) serves as the single largest all payer inpatient database in the USA and provides weights for nationally representative estimates. For this reason, it serves as an appropriate approximately of the overall perioperative morbidity and mortality statistics for this and other procedures. The purpose of this study is to evaluate the perioperative morbidity and mortality, as well as demographics, of patients undergoing posterior lumbar spinal fusions from the most recent data from 2005 to 2013. Material and Methods: The NIS database was reviewed from 2005 to 2013. Patients undergoing elective lumbar fusion surgery via a posterior approach were identified by ICD-9 code. Indications specific to the lumbar spine, such as lumbar degenerative disc disease, herniated disc, stenosis, or radiculopathy were also identified by their respective ICD-9 codes. Demographics including age, sex, hospital region and teaching status, insurance status, race/ethnicity, median household income and Charlson Comorbidity Index (CCI) score were assessed. Outcomes were assessed by frequencies of complications including pulmonary embolism (PE), deep vein thrombosis (DVT), infection, cardiac, hematoma, durotomy, and mortality. Statistical analysis involved T tests, χ² analysis, and binary logistic regression with P < .001 denoting significance. Results: We identified 158,810 patients which represented an estimated 782,177 of weighted patients hospitalized for primary posterior lumbar fusion. Patients had a mean age of 55.7 (±14.2) with 56.3% being female. The majority of patients were white (84.0%), privately insured (45.0%), had a median household income of $39,000-47,999 (27.2%) and with a CDI score of .51 (±0.87). The majority of procedures were performed in the South region (42.9%), in non-teaching hospitals (51.3%), in private, not for profit hospitals (70.9%). Bone Morphogenic Protein was used in 34.4% of cases. The most common complications were durotomy (2.1%) followed by cardiac and neurologic complications (.8% each) with the least common being mortality (.1%). Conclusion: Posterior lumbar spinal fusion is a commonly used surgical approach nationally, in teaching and non-teaching hospitals, with low rates of complications and overall mortality. We expect, with the advancements in instrumentation, success rate of fusions, and an aging population, that posterior fusion will continue to see an increase in utilization by spine surgeons across the country.

1570

P225: Does Percutaneous Lumbosacral Pedicle Screw Instrumentation Prevent Long-Term Adjacent Segment Disease?

Michael Faloon ¹ , Stuart Changoor ¹ , Conor Dunn ¹ , Nikhil Sahai ¹ , Kumar Sinha ¹ , Ki Hwang ¹ , and Arash Emami ¹

¹ St. Joseph's University Medical Center, Paterson, NJ, USA

Introduction: Adjacent segment disease (ASD) is a well-known sequela of spinal fusion that is reported to occur at a rate of 2-3% per year. There is debate whether ASD is a result of the instrumentation and fusion method or, due to the natural history of the patient’s disease. Minimally-invasive percutaneous pedicle screw augmentation of lumbar interbody fusion aims to avoid disruption of posterior soft tissue stabilizers. The purpose of this study was to assess long-term clinical outcomes, with regards to ASD, in patients who underwent lumbar interbody fusion with percutaneous pedicle screw instrumentation. Material and Methods: Between 2004 and 2014, 419 consecutive patients underwent anterior, lateral, or minimally-invasive transforaminal lumbar interbody fusion with percutaneous pedicle screw placement at a single institution. Mean follow-up was 4.5 years. Primary outcome measure was reoperation due to ASD. Patients were divided into two cohorts: those who underwent revision surgery secondary to ASD and those who did not require further surgery. Radiographic parameters were performed using postoperative radiographs. Patients with pelvic incidence-lumbar lordosis (PI-LL) mismatch >10 degrees were noted. Results: Revision proportion secondary to ASD was 4.77% (n = 20). Mean time to revision surgery was 2.5 years. Revision rate secondary to ASD was 1.1% per year. Patients who developed ASD were younger than those who did not (50.5 vs 56.9 years, P = .015). There was no difference in number of levels fused between cohorts. Revision proportion secondary to ASD was similar between approaches (ALIF, LLIF, mis-TLIF). There was no significant difference in PI-LL mismatch between those who underwent revision for ASD and those who did not (22.2% v 18.8%, P = .758). Conclusion: ASD in patients who underwent percutaneous pedicle screw placement was lower than previously published rates of ASD after open pedicle screw placement. This may be related to greater preservation of the posterior stabilizing elements of the lumbar spine.

1630

P226: Over-Reporting of Disc Herniation In Lumbar Spine MRI Scans Performed for Patients with Spondylolisthesis

Hossein Elgafy ¹ , Hassan Semaan ² , Bryan Curnutte ¹ , Maxwell Cooper ¹ , Joud Obri ² , Mazzin Elsamaloty ² , and Tawfik Obri ²

¹ University of Toledo, Orthopedic, Toledo, USA

² University of Toledo, Radiology, Toledo, USA

Introduction: Spondylolisthesis is often misdiagnosed on magnetic resonance imaging (MRI) as the slip may reduce to a normal alignment when the patient lies supine. Often, disc herniation is reported at the level of spondylolisthesis. The purpose of the current study was to determine the incidence rates of disc herniation at the level of spondylolisthesis. Materials and Methods: A retrospective study included 258 consecutive patients with spondylolisthesis who had lumbar spine MRI. The archived reports were collectively put in Group 1. A musculoskeletal radiologist and a spine surgeon reviewed the imaging studies together. Their readings were referred to as Group 2. The findings of both groups were compared to evaluate whether disc herniation was overreported. Results: Group 1 reported findings of true disc herniation in 112 (41.6%) cases and pseudo disc herniation or no findings of disc herniation at the level of spondylolisthesis in 157 (58.4%) cases. Group 2 reported findings of a true disc herniation in 25 (9.3%) cases and pseudo disc herniation or no findings of disc herniation in the remaining 244 (90.7%) cases. There was a statistically significant difference in the reporting rates between these two groups (P < .02). The most overreported finding was the disc bulging (P < .01). Conclusion: The current study showed overreporting of disc herniation in lumbar spine MRI scans performed for patients with established spondylolisthesis. The majority of disc pathology at the level of spondylolisthesis are pseudo disc rather than a true disc herniation. An accurate diagnosis is vital in planning surgical intervention.

1657

P227: Do the Various Clinical Scores Used in degenerative Lumbar Spinal Stenosis Predict the Health Related Quality of Life of Patients?

Siddharth Gupta ¹ , Tungish Bansal ² , Abhishek Kashyap ¹ , and Sumit Sural ¹

¹ MAMC and LNH Hospital, Department of Orthopedics, New Delhi, India

² AIIMS, Department of Orthopedics, New Delhi, India

Study Design: Observational study. Objectives: To investigate the correlation of Short form (SF-36) score (health related quality of life index) with various commonly used clinical scoring systems, in patients with degenerative lumbar spinal stenosis (LSS). Methods: Ninety five patients aged more than 40 years with clinico-radiological features suggestive of degenerative LSS were enrolled. All patients completed 10 clinical scoring questionnaires which included SF-36, Oswestry Disability Index (ODI), Swiss Spinal Stenosis (SSS) questionnaire, Quebec pain disability (QPD), Visual Analogue Scale (VAS back and VAS leg pain score), modified Japanese Orthopaedic Association (mJOA), Pain disability index (PDI), Self-paced walking test (SPWT) and Neurologic Claudication Outcome Score (NCOS). A comparison of 8 health concepts of SF-36 and health change was done with other 9 clinical scores and they were statistically analysed and correlated. Results: The mean age was 59.02 ± 6.7 years and included 59 females (62.1%) and 36 (37.9%) males. Three of the eight health concepts namely pain, emotional well-being and energy/fatigue showed statistically significant moderate correlation with 6 clinical scores (SSS, QPD, VAS, mJOA, PDI and SPWT) (P < .05, .7 > r > .3). Additionally, the mJOA scale showed a moderate negative correlation with role limitations due to physical health, role limitations due to emotional problems, social functioning, physical functioning as well as Health change (P < .05, .7 > r > .3). Role limitations due to physical health had a moderate negative correlation with QPD scale also (P < .05, .7 > r > .3). Conclusions: Pain, Emotional well-being and Energy/fatigue showed moderate correlation with maximum number of scores and mJOA scale had a moderate negative correlation with 7 out of 8 components of SF-36 as well as Health change.

Keywords

lumbar canal stenosis; SF-36; mJOA; NCOS; ODI; VAS.

1670

P228: Considerable Functional Improvement Following Single-Level Fusion for Selected Patients With Chronic Low Back Pain

Rinse Meester ¹ , Miranda van Hooff ^{1 2} , Maarten Spruit ¹ , and Robert Jan Kroeze ¹

¹ St. Maartenskliniek, Orthopedic Surgery, Spine Unit, Ubbergen, The Netherlands

² Radboud UMC, Orthopedic Surgery, Nijmegen, The Netherlands - acknowledgment: P. Bosman 

Introduction: The evidence supporting fusion surgery for patients with chronic low back pain (CLBP) and degenerative disc disease (DDD) remains inconclusive. In literature, surgical outcomes do not seem superior to conservative treatment. Systematic and continuous outcome monitoring of fusion surgery and patient selection might improve these outcomes. A decision support tool (Nijmegen Decision Tool for CLBP [NDT-CLBP])¹ was used to facilitate the selection of patients who might benefit of single-level fusion (SLF) for single-level DDD (SLDDD) and the assessment of their postoperative functional status. Purpose: Evaluation of functional outcomes of selected patients with CLBP who underwent SLF surgery for CLBP and SLDDD. Material and Methods: A single-center historical cohort study was performed. Data were extracted from the institutional spine outcomes registry for patients (aged 18-70 years) with CLBP, debilitating on or after mechanical loading, back pain dominant over leg pain, no neurologic symptoms, surgery between January 2014 and August 2019 for SLDDD at L4-5 or L5-S1, and who preferably had a beneficial prognosis of surgical outcome as presented by the NDT-CLBP. Primary outcome measure: Functional status (Oswestry Disability Index; ODIv2.1a). Clinical relevance: minimal clinical important change (MCIC 14.9 points²) and patient acceptable symptom state (PASS; ODI≤22), which equals normal healthy functioning. Secondary outcome measures: Quality of Life (EuroQol-5D-3L; EQ-5D utility [MCIC .46] and VAS), pain intensity; Numeric Rating Scales for back and leg pain (NRS 0-10; MCIC 2.1 and 2.8), and complications. Analysis: Pre-operative and 1-year follow-up (1yrFU) assessments were tested for statistical significance, the differences in primary and secondary outcomes were determined and analyzed for clinical relevance. Results: Sixty patients, mean age 44 years (SD 7.3, 25-57yrs; 37/60 [61.7%] women), with a minimum follow-up of one year, met our inclusion criteria. Functional status (ODI) improved from 40.4 (SD 14.7) to 15.8 (SD 14.0; P < .001) at 1yrFU, with a mean improvement of 24,6 points. Clinical relevance: 72% reached MCIC and 75% reached PASS. The mean improvement of our cohort surpassed earlier defined minimal cost-effective differences for ODI, EQ-5D, and VAS back pain³. Secondary outcomes: EQ-5D Utility score improved 0.33 points to 0.83 (SD .18; P < .001). 35% showed relevant improvement. The EQ-5D VAS improved with 20.5 points to 78.0 (SD 18.6; P < ,001). Back and leg pain intensity improved respectively with 4.6 points to a mean of 2.8 (SD 2.5; P < .001) at 1yrFU and 2.2 points to a mean of 1.2 (SD 2.15; P < .001). 85% reached MCIC for back pain. Complications: In one patient the L5 screws anteriorly displaced 8mm in 3-9 months after the operation, no reoperation was necessary. For another patient a fracture of the crista bone harvesting site occurred, which was treated conservatively with good functional outcome. Conclusion: Selected patients with CLBP seem to benefit from single-level fusion. Using a decision support tool such as the NDT-CLBP, based on bio-psychosocial characteristics, might be recommended for patient selection. A prognostic profile to decide which patients may benefit and analysis on cost-effectiveness for the specific Dutch setting remains to be further studied.

References

1. Van Hooff, M. L., van Dongen, J. M., Coupé, V. M., Spruit, M., Ostelo, R. W. J. G., & de Kleuver, M. (2018). Can patient-reported profiles avoid unnecessary referral to a spine surgeon? An observational study to further develop the Nijmegen decision tool for chronic low back pain. PLoS ONE, 13(9). https://doi.org/10.1371/journal.pone.0203518

2. Parker, S. L., Adogwa, O., Paul, A. R., Anderson, W. N., Aaronson, O., Cheng, J. S., & McGirt, M. J. (2011). Utility of minimum clinically important difference in assessing pain, disability, and health state after transforaminal lumbar interbody fusion for degenerative lumbar spondylolisthesis: Clinical article. Journal of Neurosurgery: Spine, 14(5), 598-604. https://doi.org/10.3171/2010.12.SPINE10472

3. Parker, S. L., & McGirt, M. J. (2012). Determination of the minimum improvement in pain, disability, and health state associated with cost-effectiveness: Introduction of the concept of minimum cost-effective difference. Neurosurgery, 71(6), 1149-1155. https://doi.org/10.1227/NEU.0b013e318271ebde

1694

P229: The Experience of Single- and Multilevel Reconstruction Surgery of the Lumbar Spine Using ALIF in Patients With Sagittal Imbalance

Shamil Gizatullin ¹ , Viacheslav Kurnosenko ¹ , Denis Zhukov ¹ , Ilya Dubinin ¹ , and Alexander Kristosturov ¹

¹ Burdenko Clinical Hospital, Neurosurgery, Moscow, Russian Federation

Goal: To analyze the results of using different categories of ALIF cages in the correction of sagittal balance in patients with degenerative lumbar spine disease. Materials and methods: 72 patients followed ALIF surgery from 2012 to 2019. Of the 72 patients 22 (30%) were females and 50 (70%) males. The mean age was 49 years. The mean follow-up period was 3 ± .8 years. Patients were divided into the following groups: (1) single-level ALIF – 40 patients (47%), (2) multi-level ALIF - 32 (31%). All patients underwent pre- and postoperative assessment of VAS, Oswestry Disability Index, CT, MRI, sagittal balance parameters were calculated based on full body radiographs. Surgery planning was performed in the Surgimap software for each patient. 57 patients (79%) were used commercial lordotic cages with lordosis angle of 5, 10 and 12 degrees. 15 patients (21%) were required increased correction angle more than 12 degrees. Individual cages made used 3D printer technology were implemented in this cases. 10 (14%) patients underwent a single-level correction and 5 patients (7%) a multi-level correction. A retrospective evaluation of the treatment outcomes of both groups were performed one year after surgery. The severity of pain was assessed by VAS and Oswestry Disability Index. Sagittal balance parameters were estimated based on the full body radiographs: PI, PT, SS, LL and PI - LL modifier were calculated. In 10 patients of the first group (14%), axial pain syndrome associated with insufficient correction of the sagittal balance was retrospectively revealed. The VAS changed slightly from 7.88 ± .70 to 5.44 ± .87 (P < .001). The PI - LL modifier was more than 35 degrees. The Oswestry Disability Index changed from 71.81 ± 7.22 preoperatively to 39.73 ± 7.82 postoperatively. In the second group Oswestry Disability Index changed from 77.17 ± 7.71 preoperatively to 7.75 ± 2.75 postoperatively, VAS changed from 8.77 ± .70 to 1.44 ± .87 (P < .001). The PI - LL modifier was less than 10 degrees. In patients performed individual cages implantation VAS was 1-2, the PI - LL was less than 10 degrees. The Oswestry index changed from 73.55 ± 6.53 preoperatively to 5.75 ± 1.82 postoperatively, VAS changed from 7.58 ± .70 to .44 ± 0.17 (P <.001). The results of surgical treatment improved with increasing of a number of operated levels and with the use of individual cages, proving of the effectiveness of multi-level correction of sagittal balance and the feasibility of individual selection of ALIF cages. Conclusions: Despite the fact that the multi-level ALIF surgery is recommended for surgical imbalanced patients with degenerative lumbar spine disease, individual approach and planning required. In some cases, using of individual cages supposed to be the optimal solution for severe sagittal imbalance.

1697

P230: Endoscopic Foraminal Decompression as a Treatment Method in Adult Degenerative Scoliosis

Shamil Gizatullin ¹ , Alexander Kristosturov ¹ , Viacheslav Kurnosenko ¹ , and Ilya Dubinin ¹

¹ Burdenko Clinical Hospital, Neurosurgery, Moscow, Russian Federation

Goal: A valuation of the effectiveness of an isolated minimally invasive endoscopic decompression in adult degenerative scoliosis. Materials and Methods: 34 patients followed minimal invasive foraminal decompression in adult degeneration scoliosis from Jan 2018 to Oct 2019. Of the 34 patients 25 were females and 9 were males. The mean age was 63 years. The mean follow up period was 1 ± .5 years. All patients underwent pre- and postoperative assessment of VAS, Oswestry Disability Index, CT, MRI, electromyography. Sagittal balance parameters were calculated based on total body radiographs. A retrospective evaluation of the treatment outcomes were performed one year after surgery. The severity of pain was assessed by VAS and Oswestry Disability Index. Sagittal balance parameters were estimated based on the total body radiographs: PI, PT, SS, LL and PI - LL modifier were calculated. In 8 patients of the first group (23%), axial pain syndrome was retrospectively revealed. The VAS changed slightly from 8,11 ± ,67 to 5,32 ± ,51 (P < .001). The PI - LL modifier was more than 35 degrees. Cobb angle was mere then 35 degrees. The Oswestry Disability Index changed from 74,81 ± 6,32 preoperatively to 37,68 ± 3,71 postoperatively. Subsequently, 4 patients of this group underwent reconstructive surgery on the spine using pedical screws and cages. In 26 patients (77%) sagittal balance parameters were normal after surgery. The PI - LL was less than 20 degrees. The Oswestry index changed from 78,14 ± 5,68 preoperatively to 8,32 ± 1,87 postoperatively, VAS changed from 8,68 ± ,50 to 1,37 ± ,51 (P <.001). The results of surgical treatment were affected by the correct assessment of the prevailing pain syndrome, the preoperative dynamics of changes in the sagittal and frontal balance, modifier PI - LL, deformity angle. Conclusions: Isolated endoscopic decompression may be an alternative to reconstructive spinal surgery using pedical screws and cages in patients with adult degenerative scoliosis.

1715

P231: Predictive Factors in Surgical Treatment Outcome of Lumbar Canal Stenosis

Babak Mirzashahi ¹ and Saeid Besharaty ¹

¹ Joint Reconstrucion Research Center, Orthopedic Department, IKH, Tums, Tehran, Iran

Introduction: Lumbosacral spinal stenosis is a common disabling neurological disease leading to devastating clinical course in patients. Due to decreased quality life and functional abilities, nowadays surgical interventions are used for vast majority of cases. In this era determination of the predictive factors for surgical outcomes is important to improve the postoperative status. So in this study the predictive factors of surgical treatment outcomes in lumbosacral spinal stenosis cases were determined. Materials and Methods: In this prospective cohort, 120 consecutive cases under surgical intervention for lumbosacral spinal stenosis were enrolled and the outcomes were determined by comparison of ODI, VAS, and SF-36 scales in preoperative phase, one month after surgery, and 6 months later. Also the predictive roles of various clinical and demographic factors in patients were determined. Results: The mean VAS scores were 6.9, 5.7, and 3.0 points in preoperative phase, one month after surgery, and 6 months later, respectively showing statistically significant difference (P = .001). The mean scores of physical component summary in SF-36 scales were 35.6, 37.6, and 40.1 points in preoperative phase, one month after surgery, and 6 months later, respectively, showing statistically significant difference (P = .001). The mean scores of mental component summary in SF-36 scales were 39.8, 43.1, and 47.3 points in preoperative phase, one month after surgery, and 6 months later, respectively, showing statistically significant difference (P = .001). The mean ODI scores were 54.7, 49.5, and 25.4 points in preoperative phase, one month after surgery, and 6 months later, respectively, showing significant difference (P = .001). The predictive factors for pain were smoking, BMD, duration of surgery, and physical rehabilitation therapy (P < .05); but there were no predictive variables for quality of life and disability (P > .05). Conclusion: Surgical treatment outcomes are promising in cases with lumbosacral spinal stenosis and variables such as smoking, BMD, duration of surgery, and physical rehabilitation therapy may affect these outcomes in patients in six-month follow-up.

Keywords

Predictive factor, Surgical treatment, lumbosacral spinal stenosis

1743

P232: Mean Five Year Follow up Results of a Flexible Stabilisation Device in the Treatment of Lumbar Spinal Stenosis and Degenerative Spondylolisthesis

Shahnawaz Haleem ¹ , Awaiz Ahmed ² , Satish Ganesan ³ , Stephen.McGillion ⁴ , and John Fowler ⁴

¹ Royal Orthopaedic Hospital, Spinal Surgery, Birmingham, United Kingdom

² Croydon University Hospital, T&O, London, United Kingdom

³ Conquest Hospital, T&O, Saint Leonards-on-sea, United Kingdom

⁴ Southampton General Hospital, T&O, Southampton, United Kingdom

Introduction: Flexible stabilisation has been utilised in patients to maintain spinal mobility and avoid the complications of fusion surgery but previous literature has not yet established this as a viable treatment option in an increasing presentation of younger patients with back pain and degeneration of the lumbar spine. Our study was performed to evaluate the mid-term results (mean of five years follow-up) of patients treated with the Total Posterior Solutions system (TOPS) implant in the surgical management of lumbar spinal stenosis and degenerative spondylolisthesis. Material and Methods: During an 18-month period (May 2014 to December 2015), ten patients were enrolled into a non-randomised prospective clinical study. The primary indication was neurogenic claudication due to spinal stenosis with/without single level degenerative spondylolisthesis (L3 to L5 levels). Patients were evaluated with Standing AP and Lateral X-rays and MRI scans, visual analog scale (VAS) for back and leg pain, the Oswestry Disability Index (ODI) questionnaire, SF-36 health survey and the Zurich Claudication Questionnaire (ZCQ), at the pre-operative stage, 6 months, one year, two years and latest follow-up postoperatively. Flexion and Extension standing lumbar spine radiographs were obtained at 2 years to assess range of motion at the stabilised segment. Results: Ten patients (M:F = 2:8) with a mean age of 59.6 years (range 51-71) were included in the study and followed up with clinic visits and/or phone questionnaires for a mean of five years (range 55-74 months). One patient’s data was irretrievably lost for pre-operative scoring and analysis was performed for nine patients but this patient was followed up as part of the study. VAS - back pain score improved from a mean of 7.1 to 1.6 at five years (P < .0001), VAS - Left Leg pain score from a mean of 7.3 to 0.3 (P = < .0001) and VAS - Right Leg pain score from 4.7 to 1.1 at final analysis (P = < .0016). ODI scores improved from a pre-operative mean score of 51.6 to a final mean of 8.4 (P =< .0001). SF-36 PCS improved from 27.9 to a final mean of 79.8 (P = < .0001) and the SF-36 MCS from 48.7 to a final mean of 85.3 (P =< .0001). The ZCQ SSC improved from a pre-operative mean score of 59.4 to a final mean of 31.8 (P = < .0001), ZCQ PFS from 63.9 to a final mean of 31.7 (P = < .0001) and ZCQ Satisfaction scores at Six month mean score of 29.6 to a final mean of 25.5 (P = .2351). The analysis of range of motion of the stabilised segment revealed a mean neutral angle of 19° (range 4-32), mean flexion angle of 15° (range 4-29) (P = .0059), mean extension angle of 23° (range 13-39) (P = .0023) and a mean Arc of Motion of 9° (range 3-14) (P = .0040). There were no failures at 2 years and two incidental durotomies with no patient requiring revision surgery. Conclusion: The TOPS implant maintains clinical improvement and motion in the surgical management of lumbar spinal stenosis and spondylolisthesis. The motion preserving yet stabilising effect of the implant in our study indicates that this can be considered as a viable treatment option for the same presentation.

1752

P233: Does Patient Activity Following Microdiscectomy Affect Outcome?

Jack Roadley ¹ , Chris Daly ² , Myron Rogers ³ , Kylie Fryer ¹ , Phillipa Risbey ³ , Idrees Sher ^{1 4} , Scott Ayton ⁵ , Pawel Kalinowski ⁵ , and Tony Goldschlager ^{1 3}

¹ Monash Health, Department of Neurosurgery, Melbourne, Australia

² Vancouver General Hospital, Vancouver BC, Canada

³ Cabrini Hospital, Melbourne, Australia

⁴ Austin Hospital, Melbourne, Australia

⁵ Florey Institute for Neuroscience and Mental Health, Melbourne, Australia

Introduction: Lumbar microdiscectomy is currently the most commonly performed spine surgery in the world. However, there is no conclusive evidence to guide best post-operative activity practice. As a result, surgeons' post-operative advice regarding the recommended activity levels for patients is heterogenous and its’ effect on patient recovery is unknown. Previous studies have relied on patient reported levels of activity. This study aims to assess objective, real-time activity parameters and their correlation with outcomes. Material and Methods: The study included 32 patients who underwent standard lumbar microdiscectomy. Post-operative patient activity was monitored by Activ8 device (2 M Engineering, Valkenswaard, The Netherlands) which recorded sitting, standing and walking duration and intensity for 30 days. Outcomes measures assessed included visual analogue pain scale (VAS), Oswestry disability index (ODI), EuroQol (EQ-5D), short form health survey (SF-12) at 30-day, 3-month, 6-month and 12-month time points. Differences in outcome measures were assessed with linear mixed modelling. Results: Overall, there was a reduction in VAS leg and back pain following surgery (P < .05). Smoking was observed to significantly reduce 100-point health scale score (P < .05). There was no significant association between time spent sitting, standing or walking and ODI scores at any time point. Sub analysis of walking showed no association with either walking duration or walking intensity with outcome. Conclusion: There was no discernible strong difference between level or type of activity in the first 30 days and outcome up to 12 months following microdiscectomy. Higher powered studies, ideally randomised control trials comparing specific postoperative advice (such as sitting restrictions) are needed to accurately identify the relationship between activity and outcome.

1760

P234: Features of Surgical Treatment of Degenerative-Dystrophic Spinal Diseases in Elderly and Senile Patients

Dmitry Gulyaev ¹ , Ivan Kurnosov ¹ , and Denis Godanyuk ¹

¹ Almazov National Medical Research Centre, Neurosurgery, Saint-Petersburg, Russian Federation

Introduction: Degenerative-dystrophic diseases of the spine are an actual problem of our time due to their widespread prevalence among all segments of the population. Due to the increasing life expectancy, these lesions are increasingly common in elderly and senile people. Published in a 2015 literature review that examined the epidemiology of pain in the lumbar spine, 25% of the population over the age of 60 was shown to be concerned about this problem. Through the active development of technologies and surgical techniques, the number of operations for degenerative-dystrophic diseases of the spine is increasing from year to year. According to the data provided by researchers from the USA (Rajaee S.S.), the number of operations with fusion of the spinal motion segments in the period from 1998 to 2008 increased by 170.9%. According to the literature, patients undergoing surgery on the spine develop Failed Back Surgery Syndrome with a frequency of 10 to 40%. Considering this phenomenon, in modern medicine more and more attention is paid not only to the correct technical implementation of recommendations, but also to the adaptation of the treatment process to the immediate characteristics of each patient. This method is called personalized medicine. When choosing treatment tactics, nowadays, the question of a personalized approach is increasingly being raised. A feature of elderly and senile patients is age-related involutive changes in all organs and systems, which has a great impact on the patient's cognitive status. Other neuropsychological features also affect outcome. Among these features, the following are most often distinguished: depression, anxiety, some authors also have coping strategies of the patient. It is these factors that often determine the outcome of treatment because have an important effect on the process and the functional result of therapy. Objective of the Study: To improve the results of surgical treatment of degenerative-dystrophic diseases of the spine in elderly and senile patients. Material and Methods: A clinical examination, a survey on scales (MMSE, FAB, Zung scale, Spielberger's anxiety scale, Heim questionnaire, Oswestry questionnaire), neuroimaging (CT, MRI), surgical treatment (decompression and stabilization operations), outcome assessment (Macnab) 97 patients, undergoing treatment for spinal stenosis, instability of the lumbar spine. Patients were divided into 2 groups based on satisfaction with treatment results (Macnab scale). Group 1 - excellent and good results (79 patients). Group 2 - satisfactory and unsatisfactory results (18 patients). Results: Surgical treatment of patients with severe cognitive impairments, high levels of depression and anxiety, maladaptive coping strategies yielded worse treatment results (patients in group 2) than patients with normal MMSE, FAB, depression and anxiety levels, and adaptive coping. Conclusion: We associate the negative results of the treatment of patients with the severity of the formation of a new movement pattern, the patient's inability to follow the recommendations, the difficulty in adapting to a new qualitative state of health. Therefore, it is necessary to take into account the neuropsychological characteristics of patients when choosing a treatment strategy for this group of patients.

1776

P235: Surgery for Lumbar Spinal Stenosis in Patients With Mild Leg Pain Levels is Associated With Unsatisfactory Outcome

Freyr Gauti Sigmundsson ¹ , Fredrik Stromqvist ² , and Anders Möller ²

¹ Örebro University Hospital, Department of Orthopedic Surgery, Örebro, Sweden

² Skane University Hospital, Department of Orthopedic Surgery, Malmö, Sweden

Introduction: The indication for surgery in patients with lumbar spinal stenosis (LSS) is considered to be leg pain. Nevertheless, a significant part of patients operated for LSS have mild leg pain levels defined as leg pain ≤ minimally important clinical difference (MICD). Information is lacking on how to inform these patients about the probable outcome of surgery. The objective was to report the outcome of surgery for LSS in patients with a mild preoperative level of leg pain. Material and Methods: The study was a prospective cohort study including 2,559 patients operated for LSS with preoperative leg pain ≤ 3 NRS (Numerical Rating Scale) were evaluated for outcome at the one-year follow up. NRS for back pain, The Oswestry disability index (ODI) and the EuroQol (EQ-5D) were used. Results: 2007-2017 we identified 3,239 patients (14%) who had mild leg pain (≤ 3 on the NRS). In this cohort, leg pain increased 0.40 (.56 - .37) and back pain decreased 1.0 (.95 - 1.2) at the one-year follow up. The ODI decreased 11.1 (10.2 -11.4) and the EQ-5D increased 0.15 (.17 - .14). 31% reached successful outcome in terms of back pain, 43% in terms of ODI and 48% in terms of EQ-5D. 63% of the patients were satisfied with the outcome. Conclusion: A minority of patients with mild leg pain levels operated for LSS attain MICD for back pain, ODI and EQ-5D. The results from this study can aid the surgeon in the shared decision-making process before surgery.

1876

P236: Anterior Versus Posterior Approach in Lumbar Interbody Fusion: Comparison of Functional an Radiological Outcome During A Learning Curve

Mouadh Nefiss ¹ , Bousrih Anis ¹ , Ayari Sakr ¹ , Ben Ayed Mehdi ¹ , Ezzaouia Khelil ¹ , Bouzidi Ramzi ¹ , and Tborbi Anis ¹

¹ Mongi Slim Hospital, Orthopedic Surgery Department, La Marsa, Tunisia

Introduction: The posterior approach for lumbar interbody fusion is the standard approach of the last decades. Nowadays, the anterior and lateral approaches have become more popular. Each technique has its advantages and limitations however there is a lack of evidence and consensus regarding the results of each technique over the other. The aim of our work was to compare functional and radiological results in degenerative lumbar spine surgery with interbody fusion between the posterior and anterior approaches during a learning curve. Material and Methods: We reviewed retrospectively the records of patients operated in our department between 2015 and 2019 who had interbody lumbar fusion. Patients were divided into 2 groups according to the approach (Anterior and Posterior). For the functional assessment, we used the Oswestry Disability Index (ODI) and the core outcome measures index (COMI score). Standard radiological exploration and magnetic resonance imaging were performed pre-operatively and lumbar scan at 6 months post-operatively. SPSS version 20 software was used for statistical analysis. Results: The first group consisted of 23 posteriorly operated patients, including 12 PLIF and 11 TLIF. The average age was 57 years with a female predominance. The main indications were lumbar spinal stenosis (40%), and spondylolisthesis (25%). The preoperative functional evaluation showed a mean ODI of 60.5% and a mean COMI score of 5.83. The mean ODI was 27% and the mean COMI score was 2.56 at the last fellow up. The second group consisted of 19 patients undergoing anterior surgery, including 15 OLIF and 4 ALIF. The average age was 49 years with a female predominance. The main pathologies were degenerative disc disease (57%) and spondylolisthesis (35%). The preoperative functional evaluation showed a mean ODI of 61% and a mean COMI score of 5.7. At the last fall, the mean ODI was 17% and the mean COMI score was 1.9. Both groups were statistically comparable. We did not find a significant difference between the 2 groups in terms of operating time and blood loss. For the functional evaluation, the results of the anterior group were better than the posterior group but the difference was not statistically significant. In addition, no cases of non-fusion were found for the 2 groups. Conclusion: Lumbar degenerative disease is a common cause of disability especially in the aging population. Interbody fusion is an excellent surgical option to relieve pain and stabilize the painful unstable segment. Anterior approaches have shown a discreet superiority in terms of functional recovery. But radiologically, the results were similar.

1894

P237: Fast Track Protocol for Lumbar Disc Hernia (LDH) Surgery During the COVID-19 Pandemic

Karen Weissmann ^{1 2} , Francoise Descazeaux ³ , Carlos Huaiquilaf ^{2 4} , Marcelo Costa ⁴ , and Diego Alvarez ⁴

¹ Universidad de Valencia, Valencia, Spain

² Universidad de Chile, Santiago, Chile

³ MEDS, Santiago, Chile

⁴ Redsalud, Santiago, Chile

Introduction: Enhanced recovery uses evidence-based medicine to diminish surgical stress in surgery, improving patient satisfaction and shortening length of stay (LOS). This study was developed due the COVID-19 pandemic during which a solution had to be given to patients with pain and/or neurological deficit due to lumbar disc hernias, but operating room time was restricted, and hospital beds were unavailable. Material and Methods: 2 cohorts: Control group (Standard Recovery (SR)) and fast-track group (FT). Inclusion criteria: 18 to 65 years old, primary LDH, Body Mass Index (BMI)<40Kg/M2, Comorbidities: compensated high blood pressure or insulin resistance. Exclusion criteria: Coronary disease, Type II Diabetes, BMI >40 Kg/M2, smoker, social issues, previous tumoral, traumatic, infectious or congenital lumbar pathology and psychiatric pathology. We measured clinical, surgical and administrative parameters. Surgery was by microscopic discectomy for both groups, post-operative analgesia for FT group included a buprenorphine patch (5ug/hr.) for 3 days. Follow - up was 30 days. Statistical analysis was made with Chi2 (P < .005). Results: 36 patients, 18 (SR), 17(FT). There were no demographic differences between the two groups or statistically significant differences regarding type and place of work, health insurance, level and side of LDH, weight, height, BMI, VAS, postoperative nausea and vomit (PONV), ODI before and after surgery, neurologic deficit, hematocrit/hemoglobin, American Society of Anesthesiologist score (ASA), comorbidities, use of antibiotics, duration, and bleeding. We found statistically significant differences in favor of the FT group in length of stay (P = .002) and radicular VAS after 24 hours (P = .029). We found no differences in lumbar VAS or ODI at 24 hours, lumbar and radicular VAS at 30 days, complications, readmission rate at 30 days, recurrence of LDH, work leave and length of post-operative physiotherapy. Conclusion: Fast-track protocol for lumbar herniated disc surgery is at least equivalent to a standard care protocol allowing for shorter length of stay and eventually less costs.

1896

P238: LLIF and Percutaneous Fixation During the Pandemic: Safety and Cost-Effectiveness of Spinal Anesthesia and Conscious Sedation

Alessandro Ramieri ¹ , Georgios Bakaloudis ² , and Angelo Mazzarino ²

¹ Sapienza University, Rome, Italy

² Guarnieri Hospital, Rome, Italy

Introduction: In the covid era, spinal surgery has seen a huge reduction in the number of operations everywhere, even over 50%, with a significant negative impact, including economic ones. The resources were therefore allocated to neoplastic or traumatic cases with neurological deficits. The workloads for the anesthesiology teams were enormous, both in the operating room and the ICU. Material and Methods: After the inflection point, we were able to resume the elective surgical activity on lumbar degenerative deformities associated with segmental stenosis in 43 adults without comorbidities. We performed the indirect segmental decompression by MIS-LLIF and percutaneous posterior lumbar fixation using a spinal anesthesia (naropina .5 percent 10-12,5 mg plus morfine) with preservation of the motor skills of the lower limbs and without monitoring. Results: Spinal anesthesia allowed us to perform 1 or 2 level LLIF and fix percutaneously the lumbar spine up to 5 levels in single lateral position. We found no major complications. However, patients, who were awake during surgery, complained some discomfort and / or pain at the highest levels of stabilization (L1-L2) during screw placement and insertion. Some of them exhibited a post-operative painful suprafascial bleeding suffusions which all resolved within 15-20 days and did not require transfusions. We had no new Covid infections, no post-operative blood transfusions and only 1 case transferred in ICU. Conclusion: Elective orthopedic surgery should be planned and organized in advance to achieve optimal results. In the Covid-19 era, in line with the scientific guidelines and adapted to individual healthcare facilities and resources, surgical procedures in adult population with degenerative deformities and stenosis are possible and should be mininvasive. MISS surgery under spinal anesthesia seemed to provide the lowest risk for a post-operative intensive care. Our type of spinal anesthesia with preservation of motor skills was enough to combined the lumbar approach by XLIF and percutaneous posterior fixation, without the support of the advanced intra-operative neuromonitoring.

1901

P239: Variation of Bone Mineral Density in the Lumbar Spine

Avani Vaishnav ¹ , Philip Louie ² , Chirag Chaudhary ¹ , Michael McCarthy ³ , Ryan Lee ⁴ , Yoshihiro Katsuura ¹ , Sravisht Iyer ¹ , Steven McAnany ¹ , Todd Albert ¹ , Catherine Himo Gang ¹ , and Sheeraz Qureshi ¹

¹ Hospital for Special Surgery, New York, USA

² Virginia Mason Medical Center, Seattle, USA

³ Indiana Spine Group, Carmel, USA

⁴ George Washington University School of Medicine, Washington, DC, USA

Introduction: Hounsfield units (HU), typically measured at L1-L2, have been identified as a surrogate marker for lumbar Bone Mineral Density (BMD). However, concern remains that L1-L2 BMD may not fully capture BMD differences throughout the lumbosacral spine and inadvertently provide inaccurate assessment. Thus, the purpose of this study was to evaluate the impact of age, gender and BMI on lumbar HU, compare the conventional L1-L2 HU measurements with the common levels of degenerative pathology, compare HU measurements among different vertebral levels and evaluate the distribution of HU within the individual vertebral bodies. Material and Methods: Consecutive patients presenting to a spine clinic between Apr’17 and Jan’2019 who underwent lumbar CT were selected. Previous lumbar surgery, tumor, fracture or infection were excluded. HU measurements were performed in 7 regions of each vertebral body: Mid-sagittal; Axial–Superior, Waist, Inferior; Axial at the waist–Anterior, Middle, Posterior. Association with age and BMI was evaluated using Pearson product-moment correlation. The difference between L1-L2 and L4 and L5 HU was assessed. Comparison of HU amongst levels and within each level was performed using ANOVA and paired t-tests. Results: 100 patients (mean age = 56yrs, BMI = 26.4 kg/m², 48% males) were included. Age showed a negative correlation with HU in all regions at all levels (P < .0001). BMI and gender did not show an association with HU. Conventional L1-L2 HU overestimated L4 and L5 HU by at least 10 units in 32–67% of patients, depending on the region. S1 demonstrated higher HU than L3 (P = .025) and L4 (P = .029) in the mid-sagittal plane, and higher HU than all other levels in the Superior (P < .0001) and Waist [overall (P < .0001), and anterior (P < .0001), middle (P < .0001) and posterior (P < .0001 to P = .016)] regions in the axial plane, with no other between-level differences. From L1 to L4, HU in the Superior region was significantly lower than that in the Inferior region (P < .0001 to P = .003). The opposite was seen at S1, with a decrease in HU from Superior to Waist to Inferior (P < .0001). At all levels, HU was lower in the Posterior region compared to the Anterior and Middle (P < .001), with no difference between Anterior and Middle (P > .05). Conclusion: Although BMD at L1-L2 is often used as a marker of lumbosacral BMD, it may overestimate BMD of other levels. Furthermore, all levels demonstrated differences among various regions. These findings suggests the need for more detailed BMD estimation, especially in patients undergoing spinal instrumentation in whom variations in local BMD can be used to guide surgical planning and could potentially impact clinical outcomes.

1945

P240: The Influence of Posterior Lumbar Interbody Fusion on Sagittal Balance Parameters

Khalil Habboubi ¹ , Hassen Makhlouf ¹ , Meddeb Mehdi ¹ , Mzid Ahmed ¹ , Lanouar Bouzid ¹ , and Mondher Mestiri ¹

¹ Kassab Institute, Tunis, Tunisia

Introduction: Surgery of the degenerative lumbosacral spine is experiencing a growing interest in interbody fusion with cages. The sagittal balance has an important place in the spinal pathology, enabling a comprehensive analysis of the static disorders. The aim of our study was to study the influence of posterior lumbar interbody fusion posteriorly (PLIF) on lumbar-pelvic parameters and sagittal balance. Methods: This was a retrospective study including 31 patients who had PLIF, over a period of 10 years with a mean follow-up of 5.6 years. All patients were investigated by telemetric radiographs of the spine from the front and side, in knee extension, with centered radiographs of the lumbar spine. For the assessment of functional impairment, we used the score of Beaujon-Lassalle (B-L) and the Oswestry index of disability (ODI). Results: The average age was 46 years, with a sex ratio of 0.4. The etiology was dominated by spondylolisthesis in 25 cases (20 spondylolysis and 5 degenerative) and 6 cases of degenerative discopathy. The study of spinal statics helped find 80% of types 3 and 4 backs. The lumbar-pelvic parameters averaged 53° for the pelvic incidence (PI), 35° for the sacral slope (SS) and 17° for the pelvic Version (PV). The average value of the T9 sagittal offset was 11° and 54 mm for the C7 plumb line. Functionally, we found a B-L score of 8.4 points on average and an average ODI of 57.9%. Postoperatively, we found 58% of types 3 and 4 backs. We did not find statistically significant differences in the pelvic parameters at last follow-up except for the T9 sagittal offset (P = .003) and C7 plumb line (P = .001). 71% of patients had a well-balanced back. No parameters studied had significant superiority on functional recovery. Conclusions: Many works have allowed a better understanding of the fusion by incorporating it into the scheme of static and dynamic spine. Preservation or optimization of sagittal balance are at present part of the specifications of lumbosacral arthrodesis. Only the restoration of balanced spinal statics (normal values of the C7 plumb line and T9 sagittal offset) guarantees us excellent functional and radiographic results and a solid fusion of interbody arthrodesis without repercussions on adjacent discs. It’s necessary to analyze the sagittal balance parameters in the management of degenerative lumbar spine. This will determine the type and modalities of future surgery.

1962

P241: Selective Fusion at Fractional Curve as an Alternative for Adult Degenerative Scoliosis

Xilin Liu and Jiang Hu ¹

¹ Sichuan Provincial People's Hospital, Orthopedics, Chengdu, China

Introduction: Primary adult degenerative scoliosis (ADS) develops as at least one intervertebral disc degenerated asymmetrically. Unlike AIS, the most common complaint for ADS patients is pain and disability. Thus, radiculopathy is considered as the main reason that leads to surgery especially for non-imbalanced ADS patients. As the “fractional curve” (FC) is defined as compensatory minor curve under the major lumbar/thoracolumbar scoliosis, many has found that FC region (often L3-S1) to be symptomatic levels that cause radiculopathy due to pinched exiting nerve root in the collapsed foramen(s) at the concave site. We thus treated a group of selective ADS patients using selective decompression and fusion surgery at FC and stenosis levels, comprehensive analysis was then made for evaluation. Material and Methods: All the included ADS patients underwent selective decompression and fusion surgery at FC level, using transforaminal/posterior lumbar interbody fusion(T/PLIF) in either open or minimally invasive surgery (MIS) fashion. Severely imbalanced ADS Patients, rigid spine with SVA < 6 cm, PT < 35°, or PI-LL mismatch<40°, were excluded. If severe stenosis was found at above or below, additional level (but no more than 4 levels in total) can be fused. Pre- and post-operative (at last follow-up) data, such as VAS score (back, leg), Oswestry Disability Index (ODI), coronal Cobb angle, PT, LL, SVA, PI-LL, were collected for analysis. Paired T-test were used to assess differences between groups (pre- and post-operative), statistical significance was set at P < .05. Results: Twelve ADS patients, eight males, four females, all had both back and leg pain, with a minimum of 11 months follow-up, were included in this study. The mean age was 53.8 ± 2.8 years old. Eleven underwent open T/PLIF and three had MIS-TLIF. No severe neurological complications were found, and no patient need additional surgery post-operatively. At last follow-up, the VAS back score decreased from 6.4 ± .3 to 2.0 ± .2 (P < .05), VAS leg decreased from 7.6 ± .8 to 1.7 ± .8 (P < .05), and the ODI improved from 60.8 ± 5.1% to 25.3 ± 5.4% (P<0.05). Coronal Cobb angle changed from 32.2 ± 4.0° to 12.6 ± 3.3°(P < .05), PT from 22.4 ± 5.8° to 20.0 ± 4.1°(P = .0262), LL increased from 28.0 ± 9.0° to 34.6 ± 8.6°(P < .05). The SVA, which was 23 ± 21.5 mm pre-operative and 23.3 ± 10.6mm post-operative, did not alter significantly (P = .9371). The PI-LL improved from 16.9 ± 4.4° to 10.2 ± 3.4°(P < .05). Conclusion: For selective ADS patients, selective short fusion at fractional curve may effectively relieve back and leg pain, reduce ODI, decrease coronal Cobb angle and improve lumbar lordosis and PI-LL mismatch. However, larger number of cases with long-term follow-up are required for further evaluation.

Diagnostics

18

P242: Resurgence of CT Myelogram in the era of MRI for Surgical Decision Making of Lumbar Degenerative Disc Disorder

Keyur Akbari ¹ , Vignesh Badikillaya ¹ , Muralidharan Venkatesan ¹ , and Sajan Hegde ¹

¹ Apollo Hospitals, Spine Unit, Chennai, India

Introduction: Magnetic Resonance Imaging (MRI) has become the choice of primary diagnostic imaging modality for degenerative disorders of lumbar spine over the last two decades. Despite its efficacy and non-invasive nature, clinicians are confronted with management dilemmas when the MRI findings do not correlate with clinical findings in a symptomatic patient or report several levels of significant compression. We report a series of such patients where a Computed Tomography Myelography (CTM) was performed as an additional imaging and was very helpful in surgical planning by clarifying the presence of neural compression by either disc herniation or non discogenic pathology as well as localize the level(s) of compression accurately. The purpose of this study is to compare the diagnostic utility of CTM with MRI in degenerative lumbar spine disorder. Material and Methods: We prospectively reviewed patients who presented to our outpatient clinic between October 2018 and October 2019 with symptomatic degenerative lumbar disorder in whom MRI findings did not correlate with clinical findings or showed multilevel impingement. We excluded patients with compression fracture of the lumbar spine, tumour, infection and patients in whom MRI was not performed due to contraindications. Out of 310 patients with lumbar disc disorder, 20 patients met our criteria and were included in the study. All patients had MRI scan with multiplanar T1and T2 weighted image sequences as the first diagnostic modality and CTM was performed as second procedure to obtain more information to aid surgical decision making. Patients underwent surgical management or conservative management based on CTM findings. All patients were followed up at three and six months post intervention (surgical/conservative) and patient reported outcome measures Visual Analog Scale (VAS) for backpain and leg pain and Oswestry Disbaility Index (ODI) were collected at baseline and at follow-up. Paired T test was used to compare the difference between pre operative and post operative VAS/ODI score. A P ≤ .05 was considered to indicate statistically significant difference. Results: MRI revealed compression/impingement at 38 levels whereas CTM revealed 29 levels.18 out of 20 patients underwent surgery and a total of 29 levels were decompressed as localized in the CTM. The visual analogue scale (VAS) for backpain and leg pain at baseline were 6 ± .73 and 7 ± .4 and at six months post intervention (surgical/conservative) were 2 ± .80 and .3 ± .1 respectively. ODI at baseline and at 6 months post intervention was 56 ± 6.92 and 18 ± 4.28 respectively and this improvement was significant (P < .0001). There was agreement on the number of levels between MRI and CTM in 10 cases (50%). MRI overestimated the number of involved levels in 9 cases (45%) whereas in the remaining 1 case (5%), MRI underestimated the number of involved levels. The weighted kappa value for agreement between MRI and CTM on the number of levels involved necessitating decompression was .47 (95% CI: .18 to .77; P = .0009). Conclusion: CTM is a crucial supplemental study to formulate an effective management plan in cases where MRI correlate with the clinical findings and shows a multilevel involvement to reduce postoperative morbidity.

24

P243: Bladder Scan Value in Cauda Equina Syndrome Diagnosis (a Meta-Analysis & Systematic Review Study)

Joseph Boktor ¹ , Awf Alshahwani ² , Amr Elbahi ² , Robert Smith ² , and Benerjee Purnajyoti ²

¹ University Hospitals of Wales, Trauma And Orthopaedics, Cardiff, United Kingdom

² Kettering General Hospital, Kettering, United Kingdom

Introduction: Cauda equina syndrome (CES) is a rare but serious condition that, if missed at initial presentation, can lead to serious morbidity and disability. Early diagnosis is crucial for a favorable outcome. Few studies included measurement of post-void residual urine (PVR) as an adjunct screening tool for acute CES before proceeding to MRI scan, yet there are differences in the cut-off point as a threshold volume for doing MRI amongst these studies. The aim of this study is meta-analysis and systematic review of literature that included PVR as a predictive screening tool in CES to identify the reliability of PVR and the optimal numerical value. Material and Methods: A comprehensive literature search was undertaken in PubMed, Medline, and Embase databases using our search strategy. Meta-analysis of collated data was done. Results: A total of seven studies were included from 1955 potential eligible publications. The total number of patients in these studies was 938. The number suitable for meta-analysis was 714. CES was confirmed in 73. Bladder scan diagnosed 86 and excluded 426. The sensitivity of PVR> 100ml was 64% (CI 97.5%: .44-.80), specificity 59.2% (CI 97.5%: .46 - .711), while PVR >200 showed more predictive figures, with sensitivity improved to 83.1% (CI 97.5%: .62- .94) and specificity to 93.5% (CI 97.5%: .50-.99). Conclusions: Post-void bladder scan is an essential adjunct tool in CES assessment. This meta-analysis recommends PVR more than 200 ml as the screening cut-off point being the most sensitive and specific for CES. If associated with other clinical red flags, urgent MRI would be necessary.

67

P244: The Normal Appearance of CT Myelograms

Brett Rocos ¹ , David Scourfield-Evans ² , Brathaban Rajayogeswaran ² , and John Hutchinson ²

¹ Toronto Western Hospital, Department of Spine Surgery, Toronto, Canada

² North Bristol NHS Trust, Department of Orthopaedic Surgery, Bristol, United Kingdom

Purpose: CT Myelography has been used since 1976 to diagnose neural compression in the axial skeleton. With the advent of routine MRI, its role in accurately diagnosing neural compression has been questioned as the normal appearances of the study is not defined. In this study, we examine a series of CT myelograms to define the normal appearances of the neural elements of the spine. Methods: The CT myelograms of patients with unilateral symptoms were examined by four independent physicians. The lateral extent of contrast was examined and recorded. Concordance between the recorded extent was assessed using kappa scores. Results: 36 scans were reviewed. Kappa analysis show that there is fair agreement in the lateral extent of contrast at L1, L3 and L4. At L2 and L5, agreement is slight. Conclusions: The interpretation of CT myelography shows significant interobserver variability. As a result, the usefulness of this diagnostic tool can be questioned, and if misinterpreted could lead to questionable diagnoses and inadvertently erroneous management if used in isolation.

Keywords

myelogram, computed tomography, spine, stenosis, compression, diagnosis

278

P245: EOS Analysis of Sagittal Alignment of Spine and Pelvis in Korean Adult Population

Min-gu Jang ¹ and Sang-bum Kim ²

¹ Konyang University Hospital, Orthopaedic Surgery, Daejeon, South Korea

² Chungnam National University Hospital, Orthopaedic Surgery, Daejeon, South Korea

Introduction: A retrospective study. To investigate the spinal and sagittal values of Korean adults using EOS. In Korea, there is no study to know the value of the spinal and pelvic sagittal alignment. The sagittal alignment of the spine and pelvis is generally evaluated with whole spine standing lateral radiographs. However the conventional radiograph cause increasing the risk of size measurement error. Material and Methods: From February, 2017 to April, 2019, 426 patients who have no symptoms were underwent EOS. The patients were divided into 5 groups according to their age. Measured parameters were pelvic incidence(PI), sacral slope(SS) and sagittal pelvic tilt(SPT), sagittal vertical axis(SVA), thoracic kyphosis, lumbar lordosis. Results: From February, 2017 to April, 2019, 426 patients who have no symptoms were underwent EOS. The patients were divided into 5 groups according to their age. Measured parameters were pelvic incidence(PI), sacral slope(SS) and sagittal pelvic tilt(SPT), sagittal vertical axis(SVA), thoracic kyphosis, lumbar lordosis. Conclusion: It is important to measure and accurately analyze the spine and pelvic sagittal values of healthy adults. We showed that spinopelvic parameters obtained from a database in adults in Korean populations. The normoactive values according to the patient’s age can help to estimate pre-operative lumbar lordosis restoration and can also be used as a guideline for spinopelvic sagittal balance.

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P246: Case Report of Lumbar Spine Tophaceous Gout and Review of the Literature

Ghanshyam Kakadiya ¹

¹ Topiwala National Medical College & BYL Nair Hospital, Department of Orthopaedics, Mumbai, India

Introduction: The incidence of gout in recent years is getting higher in India due to changes in diet. Tophaceous gout uncommonly affects the axial skeleton. Symptoms vary according to the differential localization of urate deposits and the diagnosis is often delayed. Lumbar spinal stenosis secondary to epidural gouty tophi has been reported occasionally. We present an unusual case of a patient with tophaceous gout of the lumbar spine and reviewed the relevant literature. Material and Methods: A patient with tophaceous gout of the lumbar spine retrospectively reviewed and reviewed the relevant recent literature. Results: A 55-year-old man was admitted with a 3-year history of lower back pain. Radiating pain to the right lower limb and intermittent claudication occurred 2 months earlier. These symptoms progressed gradually until the time of admission. He had a 4-year history of gouty arthritis for which he received medical care occasionally. Physical examination revealed tenderness on the L2–L4 spinous process with decreased activity of lumbar vertebrae. Hypoesthesia was detected in both lower limbs at the L3–L5 dermatomes areas, with the right side being more severe. The muscle strength of the lower limb was normal. The right straight leg raising sign was positive. The Babinski sign was not detected. No joint swelling or tophi were found over the elbows, knees, ankles, and toes, except one gouty tophus, which developed on the right little finger 1 month earlier. After laboratory and imaging investigations he underwent surgical decompression and stabilization. Histological analysis of the extracted specimen confirmed that it was gouty tophus. The patient’s symptoms improved progressively after the operation. He recovered very well with no complications. Conclusion: Cases of patients with spinal gout are a very rare presentation and mechanism associated with axial gout is not clear. Obesity, inactivity, and previous degenerative disc disease may be the risk factors for spinal tophus. The clinical symptoms are diverse according to the differential localization of urate deposits. It is not easy to diagnose this disease radiographically by routine radiological examination. Analysis of a biopsy specimen is the only way to confirm a diagnosis. Surgical management should be considered and recommended in patients with neurological deterioration in spinal gout. The long-term effect of treatment for spinal gout has not been reported, and thus, prospective research is necessary.

472

P247: Radiculopathy Due to venous Epidural Plexus Dilatation: How to Focus Lumbar Pain in Pregnant Women

Fernando Alvarado Gómez ¹ , Luis Carlos Morales Saenz ¹ , Maria Bedoya ¹ , Jorge Uribe Medina ¹ , Pedro Pablo Gaviria ¹ , Kenny Lopez Gomez ¹ , and Yuli Viviana Fuentes Barreiro ¹

¹ Hospital Universitario Fundación Santa Fe de Bogotá, Bogotá, Colombia

Introduction: Low back pain is a frequent pathology in pregnant women. Most of the time it is caused by biomechanical changes during pregnancy that overload the musculoskeletal structures of the abdomen and pelvis. It is uncommon to find non-mechanical characteristics of pain, in which case it is necessary to investigate other etiologies. Material and Methods: We report the case of a patient with lumbar and radicular pain, caused by the compression of the spinal roots at the lumbar level, by epidural vascular dilatation because of changes in the pressure of the abdominopelvic venous system caused by pregnancy. A search of the literature was carried out using the PUBMED database with the following strategy: ("Pregnancy" [Mesh] AND "Low Back Pain" [Mesh]) AND "Radiculopathy "[Mesh]. Results: Epidural venous plexus dilatation is described as a rare cause of lumbar and radicular pain in pregnant women. Other etiologies are described, which are highly relevant for the clinician, since it allows to increase the number of pathologies that should be taken into account when approaching this entity in the clinical setting, in order to propose differential diagnoses, always discarding those causes that represent a risk for the binomial mother-fetus. Conclusion: Lumbar pain during pregnancy is generally mechanical, however it is especially important to recognize those cases in which it is produced by other associated conditions such as venous ingurgitation of the epidural plexus. It is of the utmost importance to identify alarm signs such as radicular pain, and thus, propose differential diagnoses to guide an adequate clinical approach.

512

P248: Follow-up to a Grisel Syndrome Case: A Case Report and Literature Review

Fernando Alvarado Gómez ¹ , Luis Carlos Morales Saenz ¹ , Juan Sebastian Montes ² , and Gina Velásquez Solano ¹

¹ Hospital Universitario Fundación Santa Fe de Bogotá, Bogotá, Colombia

² Universidad El Bosque, Bogotá, Colombia

Introduction: Nontraumatic atloaxoid (C1-C2) subluxation, usually secondary to an infectious or inflammatory process of the cranial or cervical region, is defined as Grisel's Syndrome. This clinical picture was first described in 1830 by Sir Charles Bell in a patient with syphilitic ulceration of the pharynx who presented with nontraumatic atloaxoid subluxation. Material and Methods: This study presents a 5-year-old female patient admitted to the emergency department of our institution with a history of neck pain of 15 days of evolution, inclination to the right of the head with rotation to the left, spasms of the cervical muscles and jolting sensation behind your right ear without any history of trauma. Results: Conservative management was started without improvement of the deformity, therefore, it was decided to take the patient to closed reduction under anesthesia, where reduction maneuvers were performed without obtaining adequate alignment. Over time, C1-C2 rotational dislocation with significant degree of rotation to the right of the C2 vertebral body with C1-C2 right facet dislocation, abnormality of the atlanto-odontoid relationship and scoliosis is evident, at the end, decided to perform arthrodesis through the posterior route of C1 and C2 with a good postoperative result with almost total improvement in pain as in torticollis. Conclusions: The diagnosis of this pathology is mainly clinical and should be suspected in any child or patient with Down syndrome who presents with torticollis, limitations in range of motion of the neck, Cock Robin position, after a picture of rhinopharyngitis or of an otorhinolaryngology procedure. Regarding the treatment, a conservative and timely management is suggested from the moment of diagnosis focused on the reduction and stabilization of the joint, as well as control of the infectious focus, however, when this treatment fails, surgical management should be considered.

514

P249: Idiopathic Lumbosacral Plexopathy Associated With Foot Drop: A Case Report

Fernando Alvarado Gómez ¹ , Maria Bedoya ¹ , Luis Fernando Pulido Cadavid ¹ , and Yuli Viviana Fuentes Barreiro ¹

¹ Hospital Universitario Fundación Santa Fe de Bogotá, Bogotá, Colombia

Introduction: Lumbosacral plexopathy is an uncommon neurological condition clinically characterized by asymmetrical lower extremity weakness, pain and muscle atrophy, sometimes associated to mild sensory symptoms. The condition has been described to be caused by medical conditions such as neoplasia, infections, trauma, vascular lesions, amyloid infiltration, metabolic and idiopathic causes. The diagnosis is based on clinical history and neurological examination with complementary simple magnetic resonance of the lumbosacral spine. Electrophysiologic studies may also be useful in specific cases. Material and Methods: A previous healthy non-diabetic 19-year-old man consulted with a two-year history of tingling sensation on the right leg, with posterior development of left foot drop and gait impairment. Results: The electrophysiologic study was positive for radiculopathy of the L5 nerve root and the MRI showed active inflammatory plexitis of the left L5 nerve root without features suggesting a specific etiology. The blood tests and lumbar puncture were negative for metabolic, infectious, neoplastic, and inflammatory causes. Given the possible complications associated with biopsy to determine an exact etiology and the non-disabling symptoms we decided to do imaging and medical follow up. Conclusions: Lumbosacral plexopathy is an uncommon condition that is challenging to diagnose. Diagnostic tools should be carefully used to determine the appropriate surgical and non- surgical management, based on the correct identified etiology.

704

P250: Role of Invasive Urodynamic Studies in Establishing Cauda Equina Syndrome and Postoperative Recovery

Abhinandan Reddy Mallepally ¹ , Bibhudendu Mohapatra ¹ , and Kalidutta Das ¹

¹ Indian Spinal Injuries Center, Spine Services, New Delhi, India

Introduction: Cauda equine syndrome (CES) is a “possible” clinical diagnosis characterised by bowel, bladder or sexual dysfunction and sensory changes in saddle or perianal area. It is one of the few surgical emergencies in spine and a delay in diagnosis could leave the patient with permanent and disabling deficits. Unfortunately, there is no universal agreement on the definition of CES. There is no single symptom/combination of symptoms/signs which can exclude or confirm the diagnosis of cauda equina syndrome. The clinical diagnosis is associated with a high false positive rate. A missed diagnosis can permanently disable the patient whereas a misdiagnosed patient may have to undergo a surgery which does not address the cause of his bladder symptoms, there by adding to the morbidity of the procedure. The present study aims to establish the role of invasive urodynamic studies (UDS) in the diagnosis of cauda equina syndrome and also post-operative recovery. Material and Methods: A prospective study of patients who are referred to our institution with equivocal findings of IDH and bladder symptoms from January 2018 to July 2020. Patients with equivocal findings of cauda equine syndrome (bilateral/unilateral sciatica, severe LBP, saddle and/or genital sensory disturbance) and MRI evidence of compression of cauda equine were included. The patients with normal flow pattern on Uroflowmetry and no post void residue were excluded from the study. The patients with abnormal Uroflowmetry findings/high underwent UDS after informed consent and divided into acontractile, hypocontractile and normal bladder. Data regarding Perianal sensation, voluntary anal contraction, great toe perception, timing to surgery and onset of leg pain and back pain and recovery with correlation to UDS was done preoperatively and post operatively. Results: A total of 107 patients were studied (M-63/F-44). Patients with PAS present still had acontractile (61%) or hypocontractile(39%) detrusor and similarly patients with VAC present 57%had acontractile and 43%hypocontractile detrusors. 10 patients with both PAS and VAC present had acontractile detrusor. Presence of Great toe perception preoperatively showed positive correlation with PAS and VAC and improvement in detrusor function post-operatively (71%) and vice versa. 82% patients with acute leg pain <2days duration with CES showed improved when operated with in 24hrs while only 47% showed improvement when had chronic leg pain. With increasing duration of leg pain, the proportion of improved decreases. The detrusor function recovered in 66.1% when operated within 12hours of presentation, 40% in within 12-24 hours and 25% in 24-48 hours of presentation. Conclusion: The results of this study suggest that adjuvant information from urodynamic studies in combination with the examination and imaging help in accurate diagnosis even in in patients with no objective motor and sensory deficits. On the other hand, quantitative findings on urodynamic study are clearly consistent with the recovery level of patient’s urination power and can be used as a prognostic factor in these patients and represents an improvement.

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P251: Gorham-Stout Disease Associated With Chylous Effusion and Lumbar Spine Injuries: A Case Report and Literature Review

Fernando Alvarado Gómez ¹ , María Alejandra Asmar ² , Sergio Alejandro Nossa ¹ , María José Bravo Otero ³ , Carlos Montero ¹ , and Gilmar Hernández ⁴

¹ Instituto Roosevelt, Bogota, Colombia

² Universidad de los Andes, Bogota, Colombia

³ Universidad de la Sabana, Bogota, Colombia

⁴ Universidad del Rosario, Bogota, Colombia

Introduction: The Gorham-Stout syndrome is a rare pathology that leads to progressive osteolysis and bone destruction. One hypothesis is the abnormal proliferation of endothelial capillaries of vascular or lymphatic origin, producing destruction, resorption and malformation of the bone and lymphatic matrix. After a systematic review of the literature, the effusion of chylous in this syndrome is a rare presentation, in the same way, the evidence of osteolytic lesions described in vertebral bodies is even more infrequent. Materials and Methods: A 14 years old male, previously healthy, born in Villavicencio-Colombia who attended to his local hospital for presenting a 6 month clinical picture consisting in abdominal pain associated with vomiting and dizziness during the physical examination a mesogastric big mass was found. A complete abdominal ultrasound and a computed tomography was done, both showed a multilobulated cyst of 1.9 cm, located in the mesenteric, it was multilobulated and it was displacing the iliac vessels associated with multiples lytic lesion in lumbar bodies, thoracic bodies and iliac bones. Initially the cyst was drained by interventional radiology and after ten month of that procedure he was referred to our institution. Results: In the Instituto Roosevelt - Colombia, he was assessed by a pediatric surgeon who diagnosed Gorham Stout Syndrome and decided to perform surgery in order to remove the cyst. After the cyst resection was done, antibiotic therapy was given and later the abdominal pain disappear before the discharge. The pathological study determined that the cyst was benign. Four months from the discharge, the patient started with lower back pain and came back to our institution for a new assessment. The patient had pain on palpation of the spinous process of the lumbar region as the only finding, the reason why a TC of spine was done. Spine surgeon determined that all the spine (cervical, thoracic and lumbar segments) was full of multiple lytic lesions that mainly involve the medulla and very rarely the cortex destroying the cortical. The use of a corset and bone antiresorptives with bisphosphonates was the last medical indication. Conclusion: The Gorham Stout syndrome is considered as a benign and spontaneous resolution entity but has an unpredictable diagnosis with possible serious complications. The importance of an early diagnosis is to prevent those complications as pathological fractures, paralisis and even death (depending on its aggressiveness).

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P252: A Simple Decision Rule to Decide Accuracy of Measured Pelvic Incidence

Felicity Fisk ¹ , Kevin Taliaferro ¹ , and Markian Pahuta ¹

¹ Henry Ford Health System, Orthopaedics, Detroit, USA

Introduction: Pelvic incidence is a constant parameter that is unique to each patient and must be considered for surgical planning. PI is most frequently measured from plain lateral scoliosis radiographs which assumes both hip centers are perfectly aligned with the S1 endplate, however, this is not frequently obtained. The purpose of this study was to evaluate the effect variations in pelvic size, incidence, and rotation have on measured versus true PI and to develop a decision rule for determining PI accuracy. Material and Methods: Three-dimensional pelvic landmark coordinates were taken from an anthropometric study used to create crash test dummies to recreate pelvises of a small female, average male, and a large male. Each pelvis was rotated to achieve a wide range of PIs. The 3D pelvic positions were projected onto a 2D x-ray image detector using linear algebra. The pelvises were rotated in the coronal and axial planes and the PI was calculated for all 18 possible pelves in combinations of axial and coronal malrotation from -20 to +20 degrees in each plane. Results: The geometric simulation model for PI was accurate. PI deviation was found to be within an acceptable range of 6 degrees if rotation was less than 15 degrees. Pelvises with larger PIs are more sensitive, with greater PI deviation seen with smaller amounts of rotation. Diagnostic performance of the hip center rule demonstrated a sensitivity of 99.93%, 99.94%, and 99.37% for a small female, average male, and large male pelvises, respectively. Conclusion: A perfect lateral radiograph is not required for an accurate calculation of pelvic incidence within the acceptable range of 6 degrees as long as at least one hip center is contained within the bony acetabular rim of the contralateral hip. PI deviation is considered acceptable with coronal and axial rotation up to 15 degrees.

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P253: Thoracic Outlet Syndrome: Novel Contrast MRI/MRA With Functional Stress That Delineates Diagnosis and Guides Non-Surgical and Surgical Treatment

David BenEliyahu ¹ , Daichi Hayashi ² , Brian Durkin ³ , and Vijay Singh ⁴

¹ Mather Hospital Northwell Health, Back and Neck Pain Center, Port Jefferson, USA

² Stony Brook University Hospital, Radiology, Stony Brook, USA

³ Mather Hospital, Interventional Pain Management, Port Jefferson, USA

⁴ Huntington Hospital, Vascular Surgery, Huntington, USA

Introduction: Thoracic Outlet Syndrome (TOS) represents a constellation of signs and symptoms related to compression of the neurovascular bundle at the interscalene triangle, the costoclavicular, and retro-pectoralis minor spaces. There is considerable debate on diagnosis and clinical management. TOS can often present clinically like a C8 cervical radiculopathy. Most agree TOS is due to impingement of the brachial plexus (Neurogenic TOS) and/or the subclavian vessels (Arterial/Venous TOS) in the narrow passageways described. Spine Practitioners should consider the pathology of TOS in their differential diagnosis for varying cervical spine, shoulder and upper extremity pain symptoms. Definitive diagnosis of thoracic outlet syndrome is complex, and often times vague. A specific diagnostic imaging protocol that targets the Thoracic Outlet and correlates with the patients clinical presentation can help delineate diagnosis, and guide best practice non-surgical or surgical treatment. Materials and Methods: We present imaging protocols including dynamic contrast enhanced MRI/MRA sequences, and case images showing how this novel approach confirms the clinical diagnosis of TOS. We demonstrate that this protocol identifies etiologies which may be neural and/or vascular in origin. These findings guide treatment, as it precisely indicates the involved anatomical region. It allows for definitive diagnosis, and disease severity as well. We present a case series that outlines the utility of the imaging protocol, and our multidisciplinary care approach that ultimately necessitated first rib resection. Results: A 40 year old female involved in a motor vehicle accident developed neck, shoulder, arm pain with numbness of the hand and forearm at the medial aspect. Arm hyperabduction reproduced her symptoms, as did arm extension and shoulder retraction. Physical examination disclosed c8/t1 sensory hypoesthesia, weakness of the interossei, a positive Wrights, Halstead and Roo’s test. Cyanosis was noted in the affected hand, with supraclavicular fullness and edema. Myofascial trigger points were observed in the scalene, and pectoralis minor muscles. The patient was initially treated with manual therapy consisting of mobilization of the cervical spine and first rib, myofascial release, physiotherapy modalities and postural training. Interventional injections and nerve blocks were added as well. The patient only improved by 60%, so a stress MRI/MRA with contrast in neutral and in hyperabduction stress was obtained. The scans revealed a significant decrease in the costoclavicular space from 28mm to 8mm in arm hyperabduction with significant compression of the brachial plexus, and the subclavian vessels. Subclavius muscle hypertrophy, and loss of perineural fat was also seen. The patient was then referred to a thoracic surgeon who performed a first rib resection, scalenectomy, and subclavius resection. The surgeon used a robotic trans-axillary approach. The patient was completely asymptomatic post-surgery. Conclusion: We present a novel imaging protocol for TOS as well as a unique multidisciplinary and collaborative treatment approach, that ranges from manual and physical therapy, to ultrasound guided nerve blocks, to surgical first rib resection. We detail a case with a successful outcome of TOS, and our patient specific approach that mitigates much of the ambiguity involved with the diagnosis and efficacious treatment of thoracic outlet syndrome.

1711

P254: Congenital Dislocation of the Sacrum: About a Case and Literature Review

Khaled Keskes ¹ , Mohamed Ben Jemaa ¹ , Mohamed Ghorbel ¹ , Achraf Lajmi ¹ , Tarak Bardaa ¹ , Wassim Zribi ¹ , Moez Trigui ¹ , Mourad Aoui ¹ , and Hassib Keskes ¹

¹ Habib Bourguiba University Hospital of Sfax, Tunisia, Orthopedic Surgery and Traumatology Department, Sfax, Tunisia

Introduction: Congenital dislocation of the spine (CDS) is a rare malformation due to a developmental failure of the spine and the spinal cord at a single spinal level. The literature about this pathological entity stills poor. We report on this work a case of S1-S2 congenital dislocation discovered on a 5 year-old child. Material and Method: The case concerns a 5 year-old child who fell off his bicycle on his backside. He presented sudden onset of urinary and fecal incontinence. We found on clinical examination a sacral point of impact, perineal anesthesia and no anal tone. An MRI was done on emergency and according to its results a posterior sacral release was achieved. Results: The MRI showed an aspect of S1-S2 dislocation. During surgery, we notice a canal retraction S1-S2. The dural sac was compressed with the appearance of bluish contusion. The postoperative follow-up was favourable with Partial recovery 3days after surgery and full recovery at the end of the first week. Three years later, on the last check-up, the patient presents no neurological discomfort. Conclusion: Congenital dislocation of the sacrum is a rare lesion even not known nowadays. Urinary and fecal incontinence after a benin trauma on the sacrum can be the symptoms leading to the diagnosis of this lesion. The MRI, done in emergency, shows the lesion and indicates the adequate surgery. The posterior sacral release of the congenital lesion is sufficient and gives a complete recovery without neurological problem recurrence.

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P255: Importance of Surgical Treatment in Vertebral Osteoid Osteoma: About 3 Cases and Review of the Literature

Khaled KESKES ¹ , Mohamed Ben Jemaa ¹ , Mohamed Ghorbel ¹ , Tarak Bardaa ¹ , Ameur Abid ¹ , Moez Trigui ¹ , Kamel Ayedi ¹ , Wassim Zribi ¹ , and Hassib Keskes ¹

¹ Habib Bourguiba University Hospital of Sfax, Tunisia, Orthopedic Surgery and traumatology Department, Sfax, Tunisia

Introduction: The osteoid osteoma is a benign, highly vascularized bone lesion firstly described by Jaffe in 1935. It consists on a Small site of hyperactive osteoblasts surrounded by a crown of condensed bone. It affects particularly long bones. The spinal location is found in 10% of cases. The aim of this work is to report the clinical aspects of this localization and to determine the diagnostical and therapeutical approach. Material and Methods: We report on this work 3 cases of young women aged respectively 18, 25 and 38 years old who presented inflammatory back pain. These patients get well by using salicylates. During the painful crisis, we found an asymmetrical contracture of the para-vertebral muscles in all cases with radicular pain noted only in one case. A standard X-ray of the spine was done for the three patients. The bone scintigraphy was performed for two patients and the CT scan was performed in all cases. The diagnosis of vertebral osteoid osteoma was suspected in all cases. Our therapeutic strategy was surgical consisting in removing the nidus by posterior approach for all the patients. Results: The standard x-ray of the spine showed an aspect of a geode surrounded by osteocondensation localized on the pedicle of the first lumbar vertebra in one case. The scintigraphy showed bone-hyperfixation in the two others leading to CT scan which concluded to typical aspect of osteoid osteoma. Anatomopathological examination of the resection product confirmed the diagnosis of an osteoid osteoma. At the last check up, the three patients had no complaints, and no tumor recurrence was noted. Conclusion: The osteoid osteoma of the spine is a rare lesion occurring mostly in young subjects. Clinically, it leads to spontaneous pain, frequently nocturnal. Spinal stiffness, root pain and scoliosis may occur in young people. The spinal location of the lesion remains difficult to interpret in standard radiology. The scintigraphy allows to individualize the pain site necessarily determined by CT scan. Despite the contribution of interventional radiology and physical agents, the classical open surgical resection of the nidus remains the gold standard, allowing a complete removal of the lesion and an anapathological confirmation of the diagnosis with a lower risk of recurrence.

DISC DEGENERATION

48

P256: Treatment of a Lumbar Disc Herniation With Radiculopathy: Results of a National Survey Among Ortho-Spine and Neurosurgeons

Guisela Quinteros Rivas ^{1 2} , Ratko Yurac ² , Juan José Zamorano ² , Felipe Novoa Tonda ² , Manuel Valencia Carrasco ² , Alvaro Silva González ² , Carlos Thibaut Luarte ² , Bernardo Merello Tesser ² , and Bartolomé Marré ²

¹ Hospital Regional de Talca, Orthopedics Department, Talca, Chile

² Clínica Alemana de Santiago, Orthopedics Department, Santiago, Chile

Introduction: There are multiple treatment options for lumbar disc herniations (LDH) with radiculopathy and there is still no consensus on which one is better. The aim of this study is to describe the different types of treatments used by Chilean Ortho-Spine and Neurosurgeons for treating patients with radiculopathy due to an LDH. Material and Methods: We conducted an online survey to assess the different modalities and duration of the treatment of an LDH with radiculopathy in Chile. The survey was sent via email between July and September 2019 to Ortho-Spine surgeons of the Spine Chapter of the Chilean Society of Traumatology and Orthopaedics; and to Neurosurgeons, both members and non-members of the Chilean Society of Neurosurgery. Descriptive statistical analysis was performed using Stata 15.0. Results: The survey was sent to 380 surgeons and 159 responded (65% Neurosurgeons and 35% Ortho-Spine surgeons). Regarding the workplace of the responding surgeons, 56% worked in a public hospital, 41% in a private institution and 3% in a Workers’ Compensation hospital. Fifty-two percent reported that 76-100% of their monthly clinic was spine related. The most frequently used conservative treatment was a combination of analgesics, nonsteroidal anti-inflammatory drugs (NSAIDs) and pregabalin (45% of the responding surgeons). Steroids, either intramuscular, PO or IV were used by 32% of the respondents (60% of whom were Ortho-Spine surgeons). Seventy-eight percent of the doctors denied the use of alternative therapies, 5% used a lumbar brace, 4% prescribe acupuncture sessions, while 5% made a referral for chiropractic manipulation. Seventy-eight percent of the surgeons used some kind of activity limitation as part of the initial treatment. Half of the responding specialists considered a failed conservative treatment if no success was observed after 3 to 6 weeks of treatment, 41% after 6 to 12 weeks, 3% with under 3 weeks and 6% with over 12 weeks of treatment. Thirty-three percent of the doctors (90% Neurosurgeons) did not use epidural steroid injections (ESI) as part of their conservative treatment. Among those who indicated ESI, 35% used the interlaminar approach, 27% the transforaminal approach and 4% a caudal approach. Three out every four doctors indicated only one ESI, while only 7% performed two injections before considering surgery. Eighteen percent also performed additional interventional procedures together with the ESI: 50% did facet joints injections, 45% did selective nerve root blocks (10% did both facet joints and nerve root injections) and up to 1% performed other type of procedures, such as piriformis, psoas and/or quadratus lumbar muscle injections, intradiscal ozone injection and neural therapy. Traditional microdiscectomy was the most frequent surgical technique (91%), whereas 7% of the surgeons preferred a tubular discectomy and only 2% indicated an endoscopic resection of the herniation. None of the answers to the survey’s questions presented statistically significant differences between Ortho-Spine and Neurosurgeons, probably due to a small sample size. Conclusion: Treatment for an LDH with radiculopathy differs among Chilean Spine Surgeons, in spite of the availability of National Guidelines. No statistically significant differences were identified when comparing Ortho-Spine and Neurosurgeons.

416

P257: Effectiveness of Transforaminal Epidural Steroid Injection on Lumbar Herniated Disc With Radiculopathy - A Clinical Study

Harsh Agrawal ¹ , Sunil Bhosale ¹ , Sudhir Srivastava ¹ , Aditya Raj ¹ , and Atif Naseem ¹

¹ Seth GS Medical College and KEM Hospital, Orthopedics, Mumbai, India

Introduction: Low back pain with lower limb radiculopathy are very common conditions. It is estimated that most people experience back pain at least once in their lifetime. Transforaminal epidural steroid injection using fluoroscopy has been becoming a very effective therapy because of its anatomic accuracy and is now becoming a standard technique. Material and Methods: Patients fulfilling the inclusion and exclusion criteria were recruited in the study after taking informed valid consent and due ethical clearance from the institute. 2% lignocaine 1 ml + triamcinolone acetate 10 mg is administered through Kambins triangle approach under fluoroscopy guidance. The efficacy of transforaminal steroid injection is done on the basis of questionnaire considering the Numeric rating score (NRS). The patients’ were followed up for 6 weeks. Results: A total of 45 patients were recruited in the study. The average age of presentation was 44.88 years with standard deviation of 8.24 years. Of the total patients 42.22% were male and 57.78% were female. 71.11% had left radiculopathy and 28.89% presented with right sided complaints. Patient with L3-L4 disc made 2.23% of the study sample. 64.44% patient had L4-L5 disc prolapse and 33.33% patient had L5-S1 disc prolapse. 75.56% patients presented as low back pain with radiculopathy. 24.44% patients had only radiculopathy. Patients with Pffirmann MRI grade III changes were only 33.33% of sample size and 66.67% patients had grade IV changes. The mean NRS score pre-procedure was found 7.27 with standard deviation .809. The mean NRS score post-procedure was 5.2 with standard deviation 1.61. The P value on comparing the two NRS score was found to be < .0001.The success rate- that is patient having pain relief post procedure was 75.6%. Conclusion: Our study has come to assess that a single dose of transforaminal epidural steroid injection in selected group of patients can significantly improve the pain relief within a short term period and thus further improve patient care and management. The fluoroscopic guidance helps in precise anatomic location and local delivery of steroid drug- thus increasing local drug concentration and help diminish their systemic side effects. Patient factors that did not have influence on the outcome were age of patient, gender, side of radiculopathy and level of disc involved. The complaints of low back pain with radiculopathy and higher Pffirmann MRI grade had a negative impact on the outcomes. An extended application for this study could be to differentiate the exact level of nerve root involvement in case of multilevel disc herniation on MRI and clinical examination.

563

P258: Superiority Analysis of Endoscopic Discectomy Compared to Microdiscectomy

Sathish Muthu ^{1 2} , Eswar Ramakrishnan ³ , and Girinivasan Chellamuthu ^{1 4}

¹ Orthopaedic Research Group, Coimbatore, India

² Government Hospital, Velayuthampalayam, Karur, India

³ Rajiv Gandhi Government General Hospital, Institute of Orthopaedics & Traumatology, Chennai, India

⁴ Ganga Hospitals, Orthopaedic Trauma Surgery, Coimbatore, India

Introduction: With the gaining popularity of the endoscopic approach in the management of lumbar disc disease, endoscopic discectomy (ED) has also become one of the common methods of surgical management.⁶ Although ED had limited indications in the earlier days, with the advancement in the technology and tools used, the domains of its use have been extended. Moreover, with its advantages like surgery under local anaesthesia, less damage to the bone and paraspinal musculature and fast postoperative recovery ED is taking over the place of MD in the management of lumbar disc disease. We performed this meta-analysis to evaluate whether Endoscopic Discectomy (ED) shows superiority compared to the current gold standard Microdiscectomy (MD) in management of lumbar disc disease. Materials and Methods: We conducted independent and duplicate electronic database search including PubMed, Embase and Cochrane Library from 1990 till April 2020 for studies comparing ED and MD in the management of lumbar disc disease. Analysis was performed in R platform using OpenMeta[Analyst] software. Results: We included 27 studies including 11 RCTs, 7 non-randomized prospective and 9 retrospective studies involving 4018 patients in meta-analysis. We stratified the results based on the study design. Considering the heterogeneity in some results between study designs, we weighed our conclusion essentially based on results of RCTs. On analysing RCTs, superiority was established at 95% confidence interval for ED compared to MD in terms of functional outcomes like ODI score (P = .008), duration of surgery (P = .023), length of hospital stay (P < .001) although significant heterogeneity was noted. Similarly, non-inferiority to MD was established by ED in other outcomes like VAS score for back pain (P = .860) and leg pain (P = .495), MacNab classification (P = .097), recurrences (P = .993) and reoperations (P = .740) and return to work period (P = .748). Conclusion: Our meta-analysis established the superiority of endoscopic discectomy in outcome measures like ODI score, duration of surgery, overall complications, length of hospital stay and non-inferiority in other measures analysed. With recent advances in the field of ED, the procedure has the potential to take over the place of MD as the gold standard of care in management of lumbar disc disease.

584

P259: Can Small Leucine Rich Proteoglycans be Ideal Molecular Targets for Regeneration in IVD? - Evidence From Proteomic Signatures of fetal, Adult and Degenerative Discs

Shanmuganathan Rajasekaran ¹ , Dilip Chand Raja Soundararajan ¹ , Chitraa Tangavel ² , Sharon Miracle Nayagam ² , Sri Vijay Anand KS ¹ , Sunmathi R ² , and Monica Steffi Matchado ²

¹ Ganga Medical Centre and hospitals Pvt Ltd, Spine Surgery, Coimbatore, India

² Ganga Research Centre, Biotechnology, Coimbatore, India

Introduction: Biological strategies to promote disc regeneration are being explored as therapeutic options in degenerative disc disease (DDD). Fetal disc cells containing notochordal cells have shown preliminary success in regenerating the extra cellular matrix (ECM) of nucleus pulposus. Small Leucine Rich Proteoglycans (SLRPs) form an important constituent of ECM and therefore an in-depth analysis of SLRPs might unravel ideal molecular targets. Materials and Methods: IVDs of 3 contrasting developmental and health status viz., IVD harvested from 24-week old fetuses (fetal disc, FD), healthy IVD harvested from brain dead alive organ donors (normal lumbar discs, ND), and degenerated discs (DD) harvested from patients undergoing surgery for DDD were subjected to ESI-LC-MS/MS analysis for the identification of proteins after proteolytic digestion. Among the total protein, SLRPs were selectively subjected to gene ontology (GO) analysis, including biological process, molecular function, and cellular component using “cluster Profiler” in R vs 3.6.1 (2019-07-05) (R Foundation, Vienna, Austria) program. In addition, pathway enrichment analysis was performed by the DAVID database and data visualization tool Cytoscape-ClueGo/CluePedia version 3.7.2 using Reactome databases. The differential expression of SLRPs and their association with Collagen content, and ECM regulators viz, Matrix Metallo Proteinases (MMPs) and their inhibitors (TIMPs) were further analyzed. Results: A total of 1,029 proteins in FD, 1,785 proteins in ND, and 1,775 proteins in DD were identified. Out of the total 60 proteoglycans reported in the literature, we observed 26 proteoglycans in our data across all the groups which constituted 15 Large proteoglycans and 11 SLRPs. The total number of large leucine-rich proteoglycans (LLRPs) identified were 8 in FD, 7 in ND, and 9 in DD, whereas the total number of SLRPs detected were 11 in FD, 9 in ND, and 10 in DD, respectively. SLRPs such as Fibromodulin (FMOD) and Biglycan (BGN) were upregulated in the FD group. On analyzing the expression of TIMPs and MMPs, DD group showed a higher expression of MMPs when compared to ND group, whereas the FD group did not express MMPs. Statistically significant decrease in abundance was noted in the expression of Lumican (LUM), Decorin (DCN), Chondroadherin (CHAD), and Prolargin (PRELP) in the DD group. The overall decrease in SLRP content of degenerate discs, was associated with decrease in Collagen, LLRP and TIMP expression. Conclusion: The various SLRPs that we identified are all known to have a beneficial influence on ECM integrity and a negative effect on the degenerative process at different stages in the evolution of degeneration. Biglycan, which is abundantly present in a fetus, may be suitable for regenerative therapy, and the other SLRPs like LUM, PRELP, DCN, and CHAD may serve the same purpose and/or as biomarkers. Our results strongly suggest that there must be an increased focus on the role of SLRPs in the understanding and prevention of DDD.

617

P260: Regulators of Extracellular Matrix of Intervertebral Discs Identified Through Proteomic Analysis of Human Intervertebral Discs

Shanmuganathan Rajasekaran ¹ , Chitraa Tangavel ² , Niek Djuric ³ , Dilip Chand Raja Soundararajan ¹ , Sharon Miracle Nayagam ² , Monica Steffi Matchado ² , and Sri Vijay Anand KS ¹

¹ Ganga Medical Centre and Hospitals Pvt Ltd, Spine Surgery, Coimbatore, India

² Ganga Research Centre, Biotechnology, Coimbatore, India

³ University Medical Centre Leiden, Neurosurgery, Zeiden, India

Introduction: Degeneration of the intervertebral disc is associated with a decrease in Extra-cellular matrix (ECM) content due to imbalance in anabolic and catabolic signaling. In another study, we profiled the core matrisome of fetal NP’s and identified various proteins with anabolic potential for regenerative therapies. This study aims to explore ECM regulators, associated proteins and secreted factors of the fetal NP. Materials and Methods: Proteomic data of 9 fetal and 7 healthy adult (age 22-79) nucleus pulposus (NP) was analysed to understand the expression pattern of ECM regulators. Al proteins that were uniquely expressed in fetal NP’s, significantly upregulated or >2 fold upregulated if the protein was expressed in <3 fetal NP’s, were selected and the respective functions are discussed. Results: Based on the selection criteria, a total of 45 proteins were identified, of which 15 were uniquely expressed in fetal NP’s, 2 showed a significantly higher expression as compared to healthy adult NP’s, and 1 protein was >2 fold higher expressed in fetal NP’s. Pathway analysis with the 18 abovementioned proteins revealed a significant upregulation of 1 pathway and 3 biological processes, in which 13 proteins were involved. Prolyl 4 hydroxylase (P4HA) 1 and 2, Procollagen-lysine, 2-oxoglutarate 5-dioxygenase (PLOD) 1, 2 and 3, and Heat shock protein 47 (SERPINH1) were involved in ‘collagen biosynthesis’ pathway. In addition, PLOD 1-3, SERPINH1, Annexin A1 and A4, CD109 and Tetranectin (CLEC3B) were all involved in biological process of ‘tissue development’. Furthermore, the second biological process ‘regulation of proteolysis’ contained CD109, CLEC3B, SERPINH1 and SERPINF1. At last, Annexin A1, A4 and A5, Galectin-3 (LGALS-3) and SERPINF1 featured ‘negative regulation of cell death’. When integrating the interaction analysis, ANXA 4 and SERPINH1 interacted directly or indirectly as initiators of all abovementioned processes. Conclusion: In addition to core ECM proteome, this study reveals fetal ECM regulators and ECM affiliated proteins of interest to study for regenerative therapies.

922

P261: Association of Disc Degeneration With Facet Tropism at Lower Lumbar Spine - A Radiological Study

Sanjay Yadav ¹ , Raj Kumar Arya ¹ , Abhinav Jha ¹ , and Saurabh Singh ¹

¹ Institute of Medical Sciences, BHU, Orthopedics, Varanasi, India

Introduction: Facet tropism (FT) is defined as asymmetry between right and left facet joints angle. Few studies have proved facet tropism increased the risks of intervertebral disc herniation, as more sagittal oriented facets joints offer less resistance to axial rotation and exerts more strain over intervertebral disc and cause annular tear. In contrast other studies have found no positive association between facets tropism and intervertebral disc herniation. This analysis was done to assess the role of facet tropism and intervertebral disc prolapse. Methods: Total 98 patients were included in the study with lower back pain. Magnetic resonance imaging was performed and analyzed. Right and left facet angles were measured on the axial section at the level of the pedicle. Patients without disc prolapse at L3-L4, L4-L5 and L5-S1 acted as control for those having disc prolapse at L3-L4, L4-L5 and L5-S1 respectively. Statistical analysis was done with SPSS, IBM corporation v22. Results: The incidence of facets tropism at L3-L4 level was 85.2% in patients with disc herniation (n = 27) while it was 56.3 % in the control group, which was statistically significant (P = .008). Similarly at L4-L5 level incidence of FT in case and control was 71.4% (n = 35) and 52.4% respectively (P = .066). At L5-S1 level incidence was 66% and 51% in case and control group respectively (P = .13). Conclusion: In this study we found positive association between facet tropism and disc herniation at L3-L4 level. At L4-L5 and L5-S1 level we found no association between FT and disc herniation.

1067

P262: Cauda Equina Syndrome Following Lumbar Disc Herniation, Neurologic Recovery - A Prospective Study

Dipak Maharjan ¹ , Subin Byanjankar ¹ , and Avinash KC ¹

¹ Green Pastures Hospital and Rehabilitation Center, Orthopedic and spinal disorder, Pokhara, Nepal

Introduction: Cauda Equina Syndrome (CES) is the only absolute indication for emergency surgical decompression for lumbar disc herniation. But in Nepal patients rarely present early. Delay in presentations is due to many factors like patient misinformation that one should not undergo surgery for spinal problems, or delay in referral by a health personnel. Materials and Methods: The study was conducted in 2 Mission hospitals in western Nepal (Tansen Mission Hospital, Tansen and Green Pastures Hospital and Rehabilitation Center, Pokhara) from May 2009 and July 2019. We prospectively followed up 4 cases of Cauda Equina Syndrome out of 194 lumbar disc herniation operated in the duration of 10 years. The mean age was 41 years with range of 34-50 years. There was a 3 female and 1 male. One patient was operated within 6 hours, 3 patients were operated after 1 week Range (7 days – 15 days). The mean follow up period was 29 with range from 2 months to 65 months. The patients were evaluated clinically for motor function, saddle anesthesia and PR examination. Bowel and Bladder symptoms were recorded preoperatively and during follow up. Japanese Orthopedic Association (JOA) scoring was done for all the patients in the pre-operative period and in the follow up. Results: JOA score improved from 8.25 To 24.75. One patient who was operated within 6 hours had complete recovery including motor, sensory, bowel and bladder. The three patients who were operated after 7 days had incomplete recovery. The severe radiculopathy was relieved. They had persisting weakness of the foot and ankle, sensation was diminished and there was incomplete bladder recovery and persisting constipation. One patient developed trophic changes on the sole bilaterally. Conclusion: Neurological recovery is poor in delayed surgery for CES secondary to lumbar disc herniation. Early diagnosis and referral by first contact health personnel could be possible by high degree of suspicion for Cauda Equina Syndrome. Surgeons need to build the confidence of patients by good communication and appropriate education to the patient thereby increasing the trust for spine surgery.

1401

P263: Management Strategies for Anderson Lesion in Ankylosing Spondylitis: A Tertiary Center Experience

Yogendra Agrahari ¹ , Nandan Marathe ² , and Harvinder Singh Chhabra ³

¹ Shree Tinau International Hospital, Orthopedics, Butwal, Nepal

² Indian Spinal Injury Center, New Delhi, India

³ Indian Spinal Injury Center, Spine Services, New Delhi, India

Introduction: An uncommon but well recognised destructive lesion occurs in vertebral bodies and intervertebral discs in ankylosing spondylitis. This pathology was first introduced by Andersson in 1937 and is hence known as Andersson Lesion (AL). AL is most commonly seen in lower thoracic and upper lumber vertebra. The cause and pathology of Andersson’s lesion is a query and inflammatory or traumatic aetiologies are suspected. The commonly accepted hypothesis has been mechanical stresses prevent the lesion from fusion and provoke the development of pseudarthrosis. Material and Methods: We retrospectively analyzed the data of 28 patients of AL at a tertiary care centre after submission of official letter to hospital record section. Clinical data in the form of pre-operative and post-operative neurology and VAS score was recorded. Demographic data in the form of patients age, sex was noted. Radiographic data in form of Xray, CT and MRI were assessed. Operative details (operative time/ mean blood loss) and complications if any were also noted. This data was compiled and a case record form was prepared. Results/Conclusion: We have given our experience with AL through this study and have also described surgical strategies for management of the same. The conclusion from our study was that all neurologically intact patients deserve a trial of conservative management as the first line treatment. However, surgical debridement, fixation and fusion is needed in patients with a neurological deficit and those who do not respond to the conservative line of management. We have tried to design a protocol for management of AL through this study. We have also given few surgical tips for thoracolumbar fixation in Ankylosing spondylitis in this study. The limitations of this study are the relatively small sample size and that experiences of a single centre are recorded. A multicentric study with a larger sample size is needed to validate our protocol.

Keywords

Andersson lesion, ankylosing spondylitis, surgical instrumentation

1679

P264: Intracranial Hypotension Due to CSF Leak Secondary to Ventral Thoracic Osteophyte Complex: Resolution After Thoracic Discectomy and Dural Repair

Bharti Kewlani ¹ , Ibrahim Hussain ¹ , Andrew Garton ¹ , Ali A. Baaj ¹ , and Jeffrey P Greenfield ¹

¹ Weill Cornell Medical College – New York-Presbyterian Hospital, Department of Neurological Surgery, New York, USA

Introduction: The hallmark symptom of intracranial hypotension (IH) is orthostatic headaches which manifests secondary to cerebrospinal fluid (CSF) hypovolemia. Well-recognized etiologies include procedures such as lumbar punctures and spinal surgery. Rarely, structural defects such as calcified disc-osteophyte complexes are the etiology, mechanically eroding through the ventral dura resulting in CSF leak and symptom manifestation. A thorough literature review noted only 24 such cases reported to date. Conservative and medical management with bed rest, epidural saline infusion, mechanical compression, and autologous blood patches are the preferred initial approach. If these fail, surgical intervention is indicated which involves primary or secondary repair of the dural defect which can be challenging due to the ventral location and limited working area around the spinal cord. Case: We report the case of a thirty-two-year-old Asian female who presented with a one-month history of progressively worsening orthostatic headaches and no abnormal findings on neurologic examination. Brain imaging demonstrated no pathology; however, an MRI of the cervicothoracic spine revealed a circumferential epidural collection extending from the mid-cervical spine to the upper lumbar spine. A dynamic CT-myelogram confirmed the leak was centered around the T2-3 disc space, where a dorsally-projecting calcified disc-osteophyte complex had eroded through the ventral thecal sac. Conservative and medical management including two epidural blood patches (EBPs) failed to alleviate symptoms indicating surgical intervention. The surgery involved a T2-T3 laminectomy, unilateral transection of the dentate ligament to mobilize the cord, and ventral dural exploration. A 1.5 cm vertical tear in the ventral dura along with the disc-osteophyte complex was visualized. A transdural discectomy was performed. The ventral dural defect was primarily repaired with two interrupted 7-0 synthetic sutures. A ventral sling of bovine pericardium was then seized and placed to create another barrier between the ventral spinal cord and the inner surface of the dura where the sutures were tied. This sling was tacked to the inner dura at the 4 corners. The patient had a lumbar drain placed that drained for 3 days and was discharged home on postoperative day 5 with complete resolution of her symptoms and no complications, which persisted through 1 year of follow-up. Discussion: A thorough review of the existing English literature revealed only 24 reported cases between 1998 and 2019 of disc-osteophyte-induced dural tear leading to IH. 79.2% patients (n = 19) had thoracic spine pathology. 46% of patients (n = 11) underwent surgery after a failed trial of EBPs and 8% of patients (n = 2) underwent surgery before trial of EBPs. Only 1 patient was a nonresponder to surgery. For the remaining 46% of patients (n = 11), the headache symptoms improved or resolved with EBPs alone indicating the benefit of conservative/medical management for dural tear secondary to a structural lesion. Conclusion: Clear guidelines regarding the management strategy of IH secondary to disc-osteophyte complexes are yet to be established. Our literature review demonstrated a 46% symptom resolution rate with conservative management including EBPs. For those who failed conservative management, surgical intervention proved effective in resolving symptoms with a 7.69% failure rate.

1765

P265: Thoracic Myelopathy Due to Ossified Ligamentum Flavum: An Analysis of Factors Affecting Outcomes

Ajoy P Shetty ¹ , Rajdeep Singh Bagga ² , Rishi Kanna ² , and Shanmuganathan Rajasekaran ²

¹ Ganga Medical Center and Hospitals, Spine Surgery, Coimbatore, India

² Ganga Medical Center and Hospitals, Coimbatore, India

Introduction: Ossified ligamentum flavum (OLF) may be an incidental finding on MRI or may present with varying degrees of neurologic compromise. Multiple factors have been purported to affect the final outcomes in patients with thoracic OLF presenting with myelopathy. The purpose of the current study was to analyse factors affecting outcomes and the impact of ultrasonic bone scalpel in patients with myelopathy secondary to thoracic OLF. Materials and methods: We retrospectively reviewed 117 patients treated for thoracic myelopathy secondary to OLF from 2010 to 2017. Only patients with complete clinical and radiological records and a minimum follow-up of two years were included. Patients with compression secondary to thoracic disc or tandem stenosis at cervical/lumbar spine were excluded. Finally, 77 patients were included for the study. In the initial 45 patients, only conventional high-speed cutting burr in combination with rongeurs (group A) was used to perform decompression. In the remaining 32 patients, ultrasonic scalpel was used alone or in combination with high-speed cutting burr for performing the decompression (group B). Demographic, clinical and radiological data were recorded. Hirabayashi recovery rate (%) used to assess recovery. Results: The mean age at surgery was 57.9 ± 9.5 years and the mean Charlson comorbidity index score was 2.7 ± 1.2. The study group had an average follow up of 60.8 ± 26.0 months. The modified Japanese Orthopedic Association (mJOA) scores on presentation and at final follow up were 4.3 ± 1.8 and 7.6 ± 1.9, respectively (P = .001). The overall recovery rate (RR in %) was 49.9 ± 23 at the final follow up. Dural tear was seen in 17 patients (22%), with four patients belonging to the US group (P = .000). Dural tear was relatively more common in patients with tuberous and round-type lesions. Dural ossification was seen in 34% of these patients. RR correlated significantly with age (P = .04), symptom duration (P = .00), severity of myelopathy (P = .000) and cord signal changes on MRI (P = .05) on univariate analysis. On multiple regression analysis, symptom duration (P = .0001), severity of myelopathy (P = .0433) and presence of cord signal changes on MRI (P = .0167) were the most important predictors of outcome. Conclusion: Pre-operative severity of myelopathy, symptom duration and presence of cord signal change were the most significant predictors of outcome in patients with OLF. Ultrasonic cutting device (UCD) significantly reduced the operative time and the incidence of dural tears.

Keywords

ossified ligamentum flavum, ultrasonic device, thoracic myelopathy, dural tear.

Epidemiology

219

P266: Comparative Analysis of Spine Related Publications Across Eleven Languages From 1950 to 2020

Nicolas Pascual-Leone ^{1 2} , Alexander Beschloss ^{1 2} , Aaron Brooking ¹ , Stephen Platcha ¹ , Vincent Arlet ¹ , and Comron Saifi ¹

¹ University Of Pennsylvania, Philadelphia, USA

² Perelman School of Medicine, Philadelphia, USA

Introduction: ‘Lost’ science refers to those scientific discoveries released in one language that are inaccessible to those who don’t speak that language. For decades, English has served as the primary language of medicine, and while the use of one language can help serve to connect medical fields, it can also alienate those who do not speak that language. In such a high volume and constantly evolving field, spine surgery would greatly benefit from improved communication across languages and thus, across the globe. By analyzing the language of all peer reviewed publications between 1950 and 2020, this study advances the discussion and elucidates the extent of potential medical breakthroughs that stay ‘lost’ in our international field of spine surgery. The identification of these trends will allow further research to be done to make spine surgery research more accessible to all. Material and Methods: Peer reviewed publications in English and the 10 non-English languages with the most publications in PubMed were analyzed in terms of total publications and spine publications from 1950-2020. These publications were collected through the use of a PubMed algorithm focused on language. The languages of interest included Chinese, Czech, English, French, German, Italian, Japanese, Polish, Portuguese, Russian, and Spanish. Results: 29,371,547 publications were analyzed for the languages of interest with 870,404 (2.9%) of those being spine pathology articles. Stratification by language showed that 86.5% of all publications and 87.2% of spine publications were in English. However, there have been 111,872 spine publications written in non-English languages. 3.0% of all publications in English focus on spine, while 3.7% and 3.7% of all Chinese and Japanese publications focus on spine, respectively. English publications have increased by 303% in all publications and 306% for spine publications between 1988 and 2019. Over the same interval, non-English languages were found to cumulatively have a decreased total number of publications and spine publications by 44.2% and 36.0%, respectively. However, Chinese (462%), Portuguese (378%), and Spanish (88%) were found to have significant increases in spine publications. Conclusion: Our data shows the majority of publications are in English, but the historic volume of publications in other languages is significant. The vast volume of English spine publications is inaccessible to non-English speaking spine surgeons. In the past 10 years, there has been an almost 40% decrease in non-English spine publications. However, since 1988, there has been a powerful surge in the number of English and Chinese publications on spine pathology. English and Chinese publications on spine pathology have increased by 306% and 462%, respectively. This may serve as a barrier to spine surgeons who only speak one or neither of these languages. Addressing this discrepancy will be vital to ensure that both National and International spine-related care improves such that patients across the world benefit from research, no matter the language or country of origin. Having established these trends in spine research across languages will help address issues related to the inaccessibility of research due to language barriers.

233

P267: Incidence of Lumbar Vertebral Fractures Based on Etiology Throughout the USA from 2010 to 2018

Jonathan Wakim ¹ , Alexander Beschloss ¹ , Thriaksh Rajan ¹ , Vincent Arlet ¹ , and Comron Saifi ¹

¹ University of Pennsylvania, Philadelphia, USA

Introduction: Lumbar vertebral fractures are debilitating injuries associated with significant patient deformity, disability, pain, and potentially neurological deficit. EQ-5D scores were nearly identical between vertebral fractures at six months after injury (0.54) and hip fractures at three weeks after injury (0.545). Vertebral fractures are also associated with significant economic impact with annual inpatient cost of treatment reaching nearly five billion dollars. The purpose of this study is to investigate the most frequent annual etiologies of lumbar vertebral fractures presented to emergency departments throughout the USA (U.S.) from 2010 to 2018. Methods: The National Electronic Surveillance System (NEISS) database was used to identify all patients who visited participating emergency departments between 2010-2018 and were diagnosed with a lumbar fracture. National estimates were verified utilizing algorithms provided by NEISS. Population estimates by age (18+) were obtained from annual U.S. Census estimates and used to calculate annual incidence rates of lumbar fractures per 100,000 people. Results: The annual incidence rate of total lumbar fractures in the U.S. increased from 14.6 to 22.5 per 100,000 people from 2010-2018 (54% increase). Between 2010 and 2018, there were 382,914 (95% CI: 382,855-382,973) lumbar fractures in the U.S, increasing from 34,328 (95% CI: 34,277-34,379) in 2010 to 57,098 (95% CI: 57,044-57,152) in 2018 (66.3% increase). Women made up 59.8% of the lumbar fractures. Mean patient age increased by 2.96 years from 65.5 (95% CI: 65.38-65.62) in 2010 to 68.4 in 2018 (95% CI: 68.32-68.48) (4.5% increase). Each investigated year, floors, stairs/steps, and ladders were the most common etiologies of lumbar fractures. Estimated sum of floor-related fractures was 80,054 (95% CI: 79,986-80,122), stair/step-related fractures: 48,274 (95% CI: 48,209-48,339), and ladder-related fractures: 31,053 (95% CI: 30,987-31,119) from 2010-2018. From 2010-2018, floor-related fractures increased: 5,482 (95% CI: 5,428-5,536) to 11,381 (95% CI: 11,330-11,432) (95% increase), stair/step fractures increased: 3,690 (95% CI: 3,641-3,739) to 6,650 (95% CI: 6,598-6,702) (80% increase), and ladder-related fractures increased: 2,752 (95% CI: 2,702-2,802) to 4,836 (95% CI: 4,782-4,890) (76% increase). The increase in these three etiologies account for 48% of the total increase of all-cause lumbar fractures from 2010-2018. Increase in annual vertebral fractures was most statistically correlated to increase in ladder-related fractures and increase in mean annual age (P < .05 and F =.0008). Conclusion: This investigation has shown that the volume of lumbar vertebral fracture has increased over the last near decade (66.3%), and that much of this increase is accounted for by floor, stair/step and ladder-related injuries (48%). Vertebral fractures have comparable disability scores to hip fractures, highlighting the need to address and lower the incidence per 100,000 of 22.5 lumbar vertebral fractures in the U.S. This study provides insight into the most common causes of lumbar fractures, being floor, stair/step and ladder-related injuries, and the at-risk population, being primarily women with a mean age of 68 years. The identification of lumbar fractures due to ladder-related injuries is a statistically significant driver of the increase in total fractures and can play a role in guiding prevention strategies for providers and inform caretakers of appropriate precautions.

266

P268: Spino Pelvic Parameters in Argentina

Alfredo Guiroy ¹ , Martín Gagliardi ¹ , Alfredo Sicoli ¹ , Ruben Morales Ciancio ¹ , Nicolas Gonzalez Masanes ¹ , and Pablo Jalón ²

¹ Spanish Hospital, Orthopedic, Mendoza, Argentina

² Hospital de Clínicas "José de San Martín", Neurosurgery, Buenos Aires, Argentina

Objective: To assess and describe spinal and pelvic sagittal parameters in a series of 100 Argentine volunteers. Material and Methods: Lateral full spine X-rays were prospectively obtained from 100 volunteers (30 males and 70 females), average age 34.14 y/o (range 18-63). All the volunteers were asymptomatic at the time of the study; subjects with a history of spine surgery, trauma and vertebral fractures, deformities observed on physical examination, known tumors, and a limb discrepancy over 2 cm were excluded. Full-length left lateral spine radiographs (36’ cassette) were made using Kodak Elite CR equipment. The volunteers were standing, with fully extended hips and knees, flexed arms and fist-on-clavicle position. The authors made the determinations for the digital X-rays using Surgimap®, version 2.2.9.9.2. The following parameters were recorded: C7 SVA (C7 sagittal plumbline), C2-C7 CL (cervical lordosis), TK (thoracic kyphosis), LL (lumbar lordosis), TPA (thoraco-pelvic angle), T1SPi (T1 tilt), PI (pelvic incidence), PT (pelvic tilt), SS (sacral slope), L4-S1 angle, L1-L4 angle, PI-LL (pelvic incidence-lumbar lordosis mismatch), CTPA (cervico-thoraco-pelvic angle). The data were included in an Excel spreadsheet (Microsoft^® 2016, version 15.26), and analyzed using Intel Core duo microprocessor E8200 2.66 Ghz and the Medcalc 11.2 software. Descriptive statistics were calculated for each parameter according to its own measure score and distribution. Estimation of the 95% references intervals and confidence intervals were calculated for each parameter. So, the level of signification obtained was = 0.05. Results: Mean for each variable was: CL -10.04, TK 30.14, T1SPi -6.5, L1-L4 -12.45, L4-S1 -46.16, CTPA 2.5, TPA 4.65, PT 11.22, PI 48.04, LL -59.10, PI-LL -11.11, C7 SVA mm -23.68. ± 2 SD for each variable was: CL (-33.26, 13.12); TK (17.15, 43.30); T1SPi (-11.78, -1.25), L1-L4 (-25.55, .25), L4-S1 (-64.44, -27.55), CTPA (0.33, 4.80), TPA (-8.64, 18.22), PT (-1.99, 24.75), PI (25.23, 71.44), LL (-78.74, -39.89), PI-LL (-29.10, 7.04), C7 SVA mm (-79.45, 32.08). Conclusion: In this prospective series of 100 adult volunteers the normal values for spinal and pelvic sagittal parameters were determined in a population in Argentina.

270

P269: A retrospective Study of Epidemiological Characteristics of Multi-Drug Resistant Spinal Tuberculosis in Indian Patients

Ghanshyam Kakadiya ¹

¹ Topiwala National Medical College & BYL Nair Hospital, Department of Orthopaedics, Mumbai, India

Introduction: Tuberculosis is the leading cause of death among infectious diseases. India has a high burden of TB and accounted for almost 13% of the world’s cases of multi drug resistant (MDR) TB. Spinal TB is one reason for the resurgence of TB in India. Few large case studies of MDR spinal TB in India have been conducted. The aim of this research was to observe the epidemiological characteristics of MDR spinal tuberculosis patients in India from 2009–2019. Material and Methods: This is a multicentre retrospective observational study. Patients’ information was collected from the control disease centre and infectious disease database of hospitals in six cities in India. A total of 3137 patients with spinal TB and 272 patients with MDR spinal TB were analysed. Results: The result showed that MDR spinal TB remains a public health concern and commonly affects patients 15–30 years of age (34.19%). The most common lesions involved the thoracolumbar spine (35.66%). Local pain was the most common symptom (98.53%). Logistic analysis showed that for spinal TB patients, residing in rural districts (OR 1.79), advanced in years (OR 1.92) and high education degree (OR 2.22) were independent risk factors for the development of MDR spinal TB. Women were associated with a lower risk of MDR spinal TB (OR .48). The most common first-line and second- line resistant drug was isoniazid (68.75%) and levofloxacin (29.04%), respectively. The use of molecular diagnosis resulted in noteworthy clinical advances, including earlier initiation of MDR spinal TB treatment, improved infection control and better clinical outcome. Conclusion: Chemotherapy and surgery can yield satisfactory outcomes with timely diagnosis and long-term treatment. These results enable a better understanding of the MDR spinal TB in India among the general public.

271

P270: Effect of COVID19 on Mental Health of Patients Awaiting Elective Degenerative Spine Surgery in the UK

Awf Alshahwani ¹ , Joseph Boktor ² , Benerjee Purnajyoti ¹ , and Amr Elbahi ¹

¹ Leicester University, Leicester, United Kingdom

² University Hospital of Cardiff, Cardiff, United Kingdom

Introduction: Novel Coronavirus (COVID19) outbreak in early 2020 has led to significant changes to the waiting list for elective spine surgery. Patients in the National Health Service (NHS) had to wait longer with increasing uncertainty on when and if they will have their surgery undertaken. This apprehension has possibly led to increased stress and mental health issues amongst patients waiting for elective spine surgery in the UK. Our aim is to determine if patients were depressed whilst waiting longer for their spine surgery during the pandemic. Methods: Elective spine patients booked before outbreak of COVID19 were included. Patients with pathologies other than degenerative spine diseases were excluded as were spine injections. Validated depression screening score (patient health questionnaire2; PHQ2) was used to screen patients for depression before and after the outbreak. Oswestry disability scores (ODI) were calculated prospectively. Results: 14 patients were included M:F = 8:6). Mean age was 62.57 years). There was no significant differences between age and PHQ2 (P = .89); sex and depression (Fischer exact test = 1; P > .05); ODI (P = .41) and type of procedure ( decompression, two level decompression, fusion and disc surgery ; P = .05) when related to diagnosis of depression. However the PHQ2 was significantly in favour of depression (score >3) in 71.4% patients compared to pre COVID19 outbreak (Fisher exact test = .02; P < .05). Conclusion: This study reports the mental health effects on patients awaiting elective spine surgery in the NHS secondary to delays and uncertainties surrounding elective surgery services related to outbreak of COVID19 patients.

321

P271: Gender Disparity in Lumbar Spine Surgery

Mark Maclean ¹ , Ryan Greene ¹ , Gwynedd Pickett ¹ , and Sean Christie ¹

¹ Dalhousie University, Division of Neurosurgery, Halifax, Canada

Introduction: Despite efforts toward gender equality in clinical trial enrollment, females are frequently underrepresented and gender-specific data analysis is often unavailable. Identifying and reducing gender bias in medical-decision making and outcome reporting may facilitate equitable health care delivery. The purpose of this study was to identify and describe gender disparities in the work-up and surgical management of patients with degenerative lumbar conditions. Materials and Methods: Consecutive patients who were 18 years or older, undergoing scheduled surgery for degenerative lumbar conditions were prospectively enrolled in the Canadian Spine Outcomes Research Network (CSORN) registry. Data was collected at three-month, one-year, and two-year post-operative follow-up visits. Retrospective analysis was conducted. The patient cohort was dichotomized by gender. Groups of covariates pertained to the pre-operative utilization of healthcare resources included medication usage, diagnostics testing, visitation to medical specialists and allied healthcare professionals. Patient reported outcome measures included pain, disability, health-related quality of life (HRQoL), expectations of surgery, and satisfaction with surgical outcome. Analysis was primarily conducted using multivariate logistic regression. Results: Data was analyzed for 5038 patients with degenerative spinal pathologies including spinal canal stenosis (40.2%), spondylolisthesis (33.2%), and disc herniation (26.6%). For all conditions, female patients had worse pre- and post-operative pain, disability, and HRQoL. However, treatment effect was similar between genders. Significant gender differences were identified for marital status, education, employment status, exercise activities, disability claims, reason for undergoing surgery, and perception of the most important change resulting from surgery. Female patients were more likely to utilize select medications, diagnostic imaging tests, non-surgical therapeutic interventions, and visit both medical specialists and allied healthcare professionals. Despite this, few gender differences were identified in pre-operative expectations, and post-operative satisfaction with surgical outcomes. Most patients had high expectations but were “much better” or “extremely satisfied” with surgical outcome. Conclusion: Significant gender differences were observed in baseline demographics, clinical assessment scores, and utilization of health care resources for patients undergoing surgery for degenerative lumbar conditions. Treatment effect, expectations, and satisfaction with surgical outcomes were similar for male and female patients.

435

P272: The Prevalence and Clinical Characteristics of Thoracic Spinal Stenosis: A Systematic Review

Guanghui Chen ¹ , Chuiguo Sun ¹ , and Zhongqiang Chen ¹

¹ Peking University Third Hospital, Beijing, China

Introduction: Thoracic spinal stenosis (TSS) is a rare disease secondary to multiple pathological changes, which differ in prevalence and clinical characteristics. The coexistence of these pathologies complicates the diagnosis and treatment of TSS. The epidemiological characteristics of these pathologies are largely unknown due to the limited case samples and regional differences. Therefore, a systematic review was conducted to elucidate the prevalence and clinical characteristics of TSS. Material and Methods: Case series and case reports on ossification of the posterior longitudinal ligaments (OPLL), ossification of the ligamentum flavum (OLF) and thoracic disk herniation (TDH) were screened from Pubmed, Embase and Web of Science databases and systematically reviewed. Epidemiological, demographic and segmental distribution data were extracted and recorded. Results: A total of 129 studies including 1935 subjects were selected, of which 361 (18.7%) were diagnosed with OPLL, 804 (41.5%) with OLF, 143 (7.4%) with OPLL+OLF and 627 (32.4%) with TDH. Most reports were from China, Japan and USA. Thoracic OPLL occurred mostly at the middle-thoracic spine (45.6%) while OLF predominately occurred at the lower-thoracic spine (64.0%). TDH was mainly localized in the lower-thoracic spine region (85.4%). Thirty-two studies involving 524 patients described spinal comorbidities, of which 52.1% had accompanying cervical diseases and 35.9% lumbar diseases. Conclusion: Thoracic OPLL and OLF are respectively predominant at the middle and lower segments, and correspondingly show higher prevalence in women and men. TDH tends to occur in the lower thoracic spine, while OPLL+OLF shows no segmental preference. All pathologies were more frequent in the late-middle aged and elderly population and multiple pathologies often coexist.

537

P273: The representation of Women on Editorial Boards of Medline Indexed Spine, Neurosurgery, and Orthopedic Journals

Miguel Bertelli Ramos ¹ , Frederico Arriaga Criscuoli de Farias ¹ , João Pedro Einsfeld Britz ¹ , Francine Würzius de Quadros ² , Ketelly Bueno Koch ¹ , Vanessa Nodari Carobin ¹ , and Asdrubal Falavigna ³

¹ University of Caxias do Sul, Cell Therapy Laboratory and Clinical Studies and Basic Models of Spinal Disorders Laboratory, Caxias do Sul, Brazil

² Moinhos de Vento Hospital, Neurology Residency, Porto Alegre, Brazil

³ University of Caxias do Sul (UCS), Health Sciences Postgraduate Program, Caxias do Sul, Brazil

Introduction: Both neurosurgery and orthopedic surgery are male-dominated specialties. However, the prevalence of women appears to be even lower in the spine surgery field. We intend to determine this prevalence on the editorial boards of spine, neurosurgery, and orthopedic journals. Material and Methods: The gender of editorial board members of Medline indexed spine, neurosurgery, and orthopedic journals was systematically analyzed during 2019, and female representation was compared among these fields. Results: In the 34 journals included (5 spine, 13 neurosurgery, and 16 orthopedic journals), women represented 8.84% (N = 185/2,094) of editors. Their representation was 5.53% (N = 30/542) in spine, 8.58% (N = 47/548) in neurosurgery, and 10.77% (108/1,003) in orthopedic journals. Only 5.4% (N = 2/37) of the Editors-in-Chief were female. The likelihood of having female editors was higher in orthopedic than in spine journals (OR = 2.06; 95% CI = 1.35-3.13; P = .001). Neurosurgery journals were more likely to have female editors than spine journals (OR = 1.60; 95% CI = .99-2.57; P = .058), although this was not statistically significant. There was no correlation between the representation of women on spine journals and their 5-Year impact factor (Spearman’s rho = .30; P = .624). Instead, in neurosurgery and orthopedic journals there was a positive correlation (Spearman’s rho = .58; P = .036 for neurosurgery and Spearman’s rho = 0.61; P = .012 for orthopedic journals). Conclusion: The representation of women on editorial boards of spine, neurosurgery, and orthopedic journals is very low. This proportion seems to be lower for spine journals, which is consistent with the lower proportion of women among spine surgeons when compared to their presence among neurosurgeons and orthopedic surgeons, according to prior censuses and surveys.

540

P274: Perceived Impact of Gender on Spine Surgery in Latin America

Asdrubal Falavigna ¹ , Miguel Bertelli Ramos ² , Frederico Arriaga Criscuoli de Farias ² , João Pedro Einsfeld Britz ² , Carolina Matté Dagostini ² , Bruna Caroline Orlandin ² , Leandro Luis Corso ² , Samantha L Morello ³ , Amy S Kapatkin ⁴ , Tatjana Topalovic ⁵ , and Matthew Allen ⁶

¹ University of Caxias do Sul, Health Sciences Postgraduate Program, Caxias do Sul

² University of Caxias do Sul (UCS), Cell Therapy Laboratory and Clinical Studies and Basic Models of Spinal Disorders Laboratory, Caxias do Sul, Brazil

³ University of Wisconsin-Madison, Madison, USA

⁴ University of California-Davis, Davis, USA

⁵ AO Foundation, Dübendorf, Switzerland

⁶ University of Cambridge, Cambridge, United Kingdom

Introduction: female physicians rarely choose spine surgery as their specialty. While the specialty’s nature and its associated lifestyle are important barriers, gender-related issues may play an important part. We aim to evaluate the perceived impact of gender among spine surgeons. Material and Methods: a web-based survey was sent to AO Spine Latin America (AOSLA) members. Data collected included personal and professional demographics, and gender-related objective and subjective experiences regarding career and personal life. Results: 223 members answered the survey, 196 (87.96%) being male and 27 (12.11%) female. Most were orthopedic surgeons (64.13%), ≥40 years (55.16%), and had <20 years of experience (69.95%). Gender discrimination was more frequent among women than among men (66.67% vs 1.02%), as did discouragement from becoming a spine surgeon, orthopedic surgeon, or neurosurgeon (81.48% vs .51%). Females reported higher rates of sexual harassment (44.44% vs 7.65%) and more often felt disadvantaged because of gender (55.56% vs 2.55%). Working harder than men to achieve the same prestige and lack of female mentorship were the main obstacles reported by women (55.56%). Residency/fellowship influenced the decision to postpone/avoid having children for 66.67% of women but only for 37.75% of men. Creation of a Women’s Committee in AO Spine was supported by 74.07% of women and 38.78% of men. Conclusion: gender-based discrimination affects women more frequently than men in spine surgery. These experiences likely contribute to the low prevalence of female spine surgeons. Efforts to combating bias and support the professional development of women in neurosurgery, orthopedics and spine communities are encouraged.

574

P275: Research Frontiers in Spine Surgery - A Scientometric Analysis of Rcts Published From 1990 to 2019

Sathish Muthu ^{1, 2}

¹ Orthopaedic Research Group, Coimbatore, India

² Government Hospital, Velayuthampalayam, Karur, India

Introduction: Spine surgery is evolving and in the due course of its evolution, it is often essential to have a comprehensive summary of the process to have a greater understanding in order to refine our future directives. With the multiplying domains of research in the spine, it has become difficult for a surgeon to find the potential hotspots in research or identify the emerging research frontiers. With the technological developments like data mining, graphic drawing, information analytics combined with the computational statistics, visualization of scientific metrology has become a reality. Scientometrics is a quantitative method of analyzing such an evolutionary process through various parameters like citation metrics, keyword and author networks. Scientometrics can visualize this panorama of information through knowledge maps to explore hotspots in research. Hence, we aim to assess the potential research domains of randomized controlled trials (RCTs) for the past three decades (1990-2019) along with their research networks and identify the hot topics for future research. Methodology: A comprehensive and systematic analysis of all the RCTs published on Spine Surgery from 1990-2019 retrieved from the Web of Science Core Collection database. Scientometric and visual analysis of their characteristics, co-operation networks, keywords and citations were made using CiteSpace software. CiteSpace was used to visualize the structure, regularity and distribution of research domains in the spine surgery and analyze the article co-citation data to mine the knowledge clustering and citation space distribution. We also analyzed the co-occurrence between the additional research units such as cooperation among various authors, institutions and countries in the field of spine surgery. Consolidating the results of the analysis we built a comprehensive knowledge map elaborating on the emerging research trend with the potential research domain from RCTs published in spine surgery. Results: A total of 696 RCTs were published in spine surgery from 1990-2019 of which the USA(n = 263) and China(n = 71) made a significant contribution. Thomas Jefferson University(n = 16) was the leading contributor to RCTs in spine surgery. Weinstein JN was the most cited author in the field followed by Deyo RA. Spine(n = 559) remained the top-cited journal among RCTs in spine surgery. On literature co-citation analysis, “spinal stenosis”, “anterior cervical discectomy and fusion”, “degenerative disc disease” and “minimally invasive decompression” were identified as the hotspots and potential research frontiers. Conclusion: Research cooperation among developed and developing nations remains crucial and needs to be strengthened. It was evident from the identified hotspots that extending the frontiers in the management of degenerative disorders of spine through further research holds the potential for advancement in spinal care.

659

P276: Predictors of Hospital Discharge Disposition Following Single-Level Lumbar Fusion Surgery

Shane Shahrestani ¹ , Xiao Chen ¹ , Alexander Ballatori ¹ , Andy Ton ¹ , Jeffrey C. Wang ¹ , and Zorica Buser ¹

¹ Keck School of Medicine, University of Southern California, Department of Orthopaedic Surgery, Los Angeles, USA

Introduction: Ongoing management of patients receiving single-level lumbar fusion emphasizes reduction of inpatient length of stay (LOS) and postoperative complication rates. Oftentimes, patient discharge dispositions are utilized as a proxy for patient health following surgical intervention. However, literature evaluating predictors of discharge location and status are limited, and those available are often outdated or utilize small patient cohorts for analysis. Here, we implement multivariate modeling in a large contemporary cohort to identify patient predictors of discharge location. Material and Methods: Using the 2016-2017 Nationwide Readmission Database (NRD), we conducted a retrospective cohort analysis of 339,597 patients admitted for lumbar spinal fusion. All patients admitted to the hospital for trauma or malignancy were excluded to minimize confounding. Predictors for discharge status included patient frailty, body mass index (BMI, kg/m²), hospital characteristics, and inpatient LOS. Routine discharges were defined as a routine discharge to a patient’s home, while non-routine discharges included transfer to a short-term hospital, skilled nursing facility, home health care, and death. Patient frailty was defined through the Johns Hopkins adjusted clinical groups frailty-defining diagnosis indicator. Statistics were conducted using RStudio, and gaussian-fitted multivariate regression models were developed with patient age, sex, and Charlson Comorbidity Index (CCI) scores as covariates. Results: The average age of all patients was 58.8 ± 14.4 years with 54.5% being female and an average CCI of 2.8 ± 1.6. A total of 116,134 (34.2%) patients experienced a non-routine discharge. Patient frailty was found to be a significant predictor of non-routine discharge (OR:1.26, 95% CI:1.25-1.27, P < .0001). In addition, patient BMIs between 40-45 (OR:1.07, 95% CI:1.06-1.08, P < .0001), 45-50 (OR:1.10, 95%CI:1.08-1.12, P < .0001), ad 50-60 (OR:1.14, 95% CI:1.10-1.17, P < .0001) were found to increase the odds of non-routine hospital discharges with incremental increases in BMI. Further, hospital bed size and hospital teaching status were both found to independently predict discharge disposition, with rural hospitals (OR:1.032, 95% CI:1.028-1.037, P < .0001) and hospitals with larger bed sizes (OR:1.023, 95% CI:1.020-1.026, P < .0001) having higher non-routine discharges. Lastly, higher patient LOS significantly predicted non-routine discharges in our patient cohort (P < .0001), with each additional day spent in the hospital increasing the risk of non-routine discharge by 2.45%. Conclusion: Contemporary management of patients receiving lumbar fusion should focus on minimizing postoperative complications with hopes of achieving high rates of routine discharges. In order to achieve this goal, a thorough understanding of perioperative predictors of non-routine discharge dispositions. Patient frailty, BMI, hospital characteristics, and LOS all independently influence discharge disposition, and further research is necessary to identify additional predictors of poor patient outcomes.

682

P277: Spine Trauma Epidemiological Profile in a Tertiary Neurosurgery Hospital in South Brazil

Guilherme Finger ¹ , Maria Eduarda Conte Gripa ² , Tiago Paczko Bozko Cecchini ² , Tobias Ludwig do Nascimento ¹ , Felipe Martins de Lima Cecchini ¹ , Ericson Sfreddo ¹ , Andre Martins de Lima Cecchini ¹ , and Asdrubal Falavigna ³

¹ Cristo Redentor Hospital, Neurosurgery, Porto Alegre, Brazil

² Brazilian Lutheran University, Canoas, Brazil

³ Caxias do Sul University, Neurosurgery Spine, Caxias do Sul, Brazil

Introduction: The incidence of spine trauma and spinal cord injury varies worldwide. Several systematic reviews analyzed articles published worldwide, but no article from Latin America was included. The objective of this paper is to perform a large series in order to analyze the epidemiological profile of patients in this scenario in the Southernmost state of Brazil. Methods: a retrospective study including spine trauma patients was performed at a tertiary hospital from January 1^st, 2013 to December 31^st, 2018. Variables analyzed include demographic data (age, gender, race), information related to the trauma (etiology, trauma mechanism, type of spine injury, number of vertebrae involved, vertebral segment involved), neurological status at hospital admission (Frankel scale), treatment performed (operative and non-operative) and the outcome (number of days in hospital, neurological outcome, and mortality). Results: A total of 808 patients were included. The mean age was 47.9 (± 19.0), and the majority were males and Caucasians. The most frequent etiology was fall from height (N = 508; 62.9%) followed by traffic accident (N = 185; 22.9%). The thoracolumbar segment was the most frequently affected, occurring in 401 (52.1%) patients, followed by cervical, thoracic and lumbar segments. The incidence of SCI was 16.7%. Non-operative treatment was indicated in 510 (63.1%) patients. Conclusion: Authors presented the largest epidemiological profile regarding spine trauma in Latin America, analyzing a total of 808 patients, which represents an incidence of 134.6 cases/year. This paper fills a gap in medical literature, which, previously, lacked the epidemiological profile of this disease in Latin America.

707

P278: The Incidence of Failed Back Surgery Syndrome and Opioid use Varies Between Inpatient vs Outpatient Lumbar Spine Surgery

Eloise Stanton ¹ , Blake Formanek ¹ , Joshua Bakhsheshian ² , Jeffrey C. Wang ¹ , and Zorica Buser ¹

¹ Keck School of Medicine, University of Southern California, Department of Orthopaedic Surgery, Los Angeles, USA

² Keck School of Medicine, University of Southern California, Department of Neurological Surgery, Los Angeles, USA

Introduction: Failed back surgery syndrome (FBSS) is a significant cause of lumbar morbidity and disability and is associated with high rates of opioid usage. However, FBSS trends and associated opioid usage have not been extensively studied. Material and Methods: Data were obtained for patients undergoing anterior lumbar fusion, posterior lumbar fusion, laminectomy, laminotomy, and discectomy procedures from January 2010 to December 2017 from the Mariner insurance database. Patient rates were analyzed to determine the rate of FBSS at six- and twelve-months post-surgery. Rates were determined for patients undergoing single/multilevel procedures according to place of service, and approach/procedure type. Opioid usage in patients with and without FBSS were analyzed at six and twelve months post-surgery. Results: From 2010 to 2017, 102,047 patients underwent lumbar fusion or decompression surgery (54% decompression procedures, 36% posterior fusions, and 8.9% anterior fusions). Of the procedures, 76% were performed in an inpatient setting, and 24% were performed in an outpatient setting. 5.4% of patients were diagnosed with FBSS within six months of the index procedure, and 8.3% were diagnosed with FBSS within twelve months. For posterior fusion surgeries, 5.7% of patients were diagnosed with FBSS within six months post-surgery, and 8.7% were diagnosed with FBSS within twelve months. For anterior fusion surgeries, 4.9% of patients were diagnosed with FBSS within six months post-surgery, and 7.7% were diagnosed with FBSS within twelve months. FBSS was observed to be higher in the inpatient (9.4%) vs outpatient (6.8)% cohort. Among all the fusion techniques, multi-level procedures had higher rates of FBSS than single-level procedures, the highest being 10% in multi-level inpatient decompression procedures. Of the patients diagnosed with FBSS within twelve months of the index procedure, 6.2% of patients were still being prescribed opioids twelve months post-surgery. The rates of continued opioid usage greatly differed based on inpatient versus outpatient setting. Among the procedures analyzed for opioid usage, there were higher rates of continued opioid use for all outpatient procedures at both six- and twelve-months post-surgery in comparison with inpatient procedures. Conclusion: While the highest rates of FBSS occurred in multi-level inpatient decompression procedures, patients had higher rates of opioid usage in the outpatient setting with decompression procedures. This preliminary data merits further investigation into the reasoning for the increased opioid prescription, possibly either increased outpatient post-procedural pain and complications, or easier outpatient access to prescriptions.

792

P279: Evaluation of Quality of Life of Patients With Idiopathic Scoliosis Through Changes in Preoperative SRS-22 Questionnaire After Follow-Up in a Specialized Center of Spine Deformities

Carlos Montero ¹ , Wilmer Godoy ¹ , María Alejandra Asmar ² , Alexander Tristancho ¹ , and Fernando Alvarado Gómez ¹

¹ Instituto Roosevelt, Bogota, Colombia

² Universidad de los Andes, Bogota, Colombia

Introduction: The Scoliosis Research Society (SRS) outcomes questionnaire evaluates disease-specific health related quality of life questions that can assess the effect of surgical correction of idiopathic scoliosis from the patient’s point of view. This questionnaire includes five domains that evaluate function/activity (Fu), self-image/appearance (Se), pain (Pa), mental health (Mh) and satisfaction (Sa) with management. It scores on a scale that ranges from 5-1 per question, being 5 the best and 1 the worst value possibly given. We studied if there were changes for each specific domain after 12 months postoperative follow-up in patients that underwent surgical correction of idiopathic scoliosis. Materials and Methods: We conducted a retrospective study using a cohort of 108 patients diagnosed with Adolescent Idiopathic Scoliosis that were prone to underwent one-stage posterior spinal arthrodesis were evaluated. The SRS-22 outcomes questionnaire was administered preoperatively, at 6 and 12-month intervals postoperatively, at times when patients assisted to clinic consult for postoperative follow-up. There was some variance in the follow-up intervals, namely an interval of 5-8 months as 6 months postoperative and 11- 16 months as 12 months postoperative. Comparisons were done only on patients that respond the questionnaire preoperatively and 12 months postoperative. A statistical significant difference was determined by a P value lower than .05. Results: Of the 108 cohort, 61 subjects had correct fulfilled preoperative survey, 19 with 6 months follow up and 24 who underwent annual control. Weekly and 3 months follow up were excluded. All patients answered the Standard SRS-22 questionnaire and the data was stored and tabulated as part of the specialized spine deformities center data. Satisfaction questions (#21-22) were not answered at preoperative consult. Average score per domain in each moment were as follows: Preoperative Fu (2.2), Pa (2), Sf (2.5), and Mh (2.1). Six months Fu (2), Pa (1.7), Sf (1,7), Mh (1.7), Sa (1.6). 12 months Fu (2.1), Pa (1,7), Sf (2), Mh (2.1), Sa (1.6). Additional analyses were performed in a 18 -patients subcohort who took preoperative and annual control with the following average punctuation per domain: Preoperative Fu (2.4), Pa (2.2), Sf (3.1), and Mh (2.3). 12 months Fu (2.1), Pa (1.8), Sf (2), Mh (2.1), Sa (1.7). In addition to the score per domain we calculated the percentage change per domain in the subcohort and found: Fu -12,5% (P < .5), Pa -18% (P < .5), Sf -35% (P < .5), and Mh -8,3% (P > .,5). Conclusion: Differences between preoperative and assessment at 12-months postoperative follow-up on the function, pain and self image domains were statistically significant, which demonstrates that surgical correction may be a good treatment option for idiopathic scoliosis. This may reflect that our patients are motivated to undergo surgical correction for health itself but also for esthetical and function reasons. As anticipated, function decreased at 6 months but returned to baseline at 12-months follow up. No statistically significant differences on the mental health domain were found. In conclusion, the SRS-22 questionnaire is a useful tool on the postoperative follow-up after surgical correction for idiopathic scoliosis from the patient’s vantage point.

951

P280: Prevalence of Thoracic Ossification of Ligamentum Flavum in Population-Based and Symptom-Based Cohorts: A Meta-Analysis

Baoliang Zhang ¹ , Zhongqiang Chen ¹ , Guanghui Chen ¹ , Xiaoxi Yang ¹ , and Tianqi Fan ¹

¹ Peking University Third Hospital, Beijing, China

Introduction: Thoracic ossification of ligamentum flavum (TOLF) is an insidious but progressive spinal condition with only surgical intervention. The epidemic characteristics of TOLF remain ambiguous due to its rarity and complexity. Therefore, a meta-analyis was conducted to determine the prevalence of TOLF from population-based and symptom-based cohorts, identified by radiological criteria. Material and Methods: MEDLINE, Embase, CINAHL, Web of Science and PubMed were searched from inception to July 2020. Studies that assessed prevalence of TOLF in population- or symptom-based cohorts using imaging techniques were included. Studies were excluded if they evaluated a targeted sample (e.g. registry patients diagnosed as OPLL) or repeated already reported data from the same cohorts. Two independent reviewers conducted pooled and quantitative analysis on overall prevalence estimates of TOLF and the effect of age and sex through Stata software 14.0. Results: Ten eligible studies were included in the final meta-analysis, including 6 studies with 13037 participants reported population-based cohorts and 4 with 8352 participants evaluated symptom-based cohort. Reported prevalence figures ranged from 14.5% to 63.9%. The crude prevalence of TOLF was 14% in the population-based cohorts (95 % CI: 6–23%, P = .001), in which males (16%, 95 % CI: 5–28 %, P = .005) appeared to have higher prevalence of TOLF than females (13%, 95 % CI: 6–19 %, P = .001). In the symptom-based cohorts, the pooled prevalence of TOLF was 34% (95 % CI: 18–50%, P = .001) and no difference was observed between males and females, with prevalence figures of 33% (95 % CI: 14–52 %, P = .001) versue 33% (95 % CI: 20–47 %, P = .001), respectivtely. In addition, the prevalence of TOLF detected by CT was significantly higher than that by MRI or X-ray whether in population-based or symptom-based cohorts. Conclusion: Based on this large-population analysis, TOLF seems to be a relatively prevalent condition with no significant gender difference, especially in symptom-based cohorts identified by CT. However, the pooled prevalence estimates should be interpreted with caution due to high heterogeneity. Further research is required to conduct more precise global prevalence estimates and related risk factors.

972

P281: Profile of Patients Submitted to the Review of Spinal Arthrodesis, Surgical Treatment of Pseudoarthrosis and its Economic Impact on the Public Health in São Paulo, Brazil

João Henrique Almeida Costa ¹ , Paulo Daniel Sousa Santa Cruz ¹ , Gustavo Gonçalves Arliani ¹ , and Victor Otávio Moraes De Oliveira ¹

¹ Prevent Senior, Ortopedia, São Paulo, Brazil

Introduction: Arthrodesis is a surgical procedure that has been widely used in recent years, especially in cases of low back pain refractory to adequate conservative treatment, with presence of signs of vertebral segmental instability associated or not with reduced disc space, to relieve the disabling pain generated by degenerative diseases. Although with good clinical results, it does not exclude complications, including pseudoarthrosis. The aim of the study is to identify and evaluate the epidemiological profile of patients undergoing arthrodesis review and surgical treatment of pseudarthrosis as its complication, its correlations in hospitalization and its economic expenditure in the SUS (Health Unic System) of the State of São Paulo, Brazil. Material and Methods: This retrospective and descriptive population-based study selected patients undergoing arthrodesis review and surgical treatment of pseudarthrosis as its complication from August 2018 to July 2019 in SUS hospitals in the State of São Paulo, Brazil. The AIHs registered in SIHSUS (Hospital Information System of the Unified Health System) were observed and the instrument used to collect these data was the DATASUS tabwin32.exe program from the Ministry of Health. Results: 113 arthrodesis revision surgical procedures were identified. With surgical treatment of pseudoarthrosis as a complication identified in the posterior thoraco-lumbosacral spine with 65.49% (n = 74) and anterior with 17.7% (n = 20), the posterior cervical spine with 10.62 % (n = 12) and 6.19% (n = 7) of the anterior route, most of them male, with 50.44% (n = 57), white with 71.68% (n = 81), 21.24% (n = 24) of patients aged 55 to 64 years, and 20.35% (n = 23) over 65 years. Patients from São Paulo state prevail with 15.04% (n = 17), followed by Franca and São José do Rio Preto, both with 7.08% (n = 8). Regarding the surgical sites, Santa Casa de Franca Hospital presented 10.62% (n = 10), followed by the Vale do Paraíba Regional Hospital in Taubaté, Santa Casa de São José do Rio Preto and Hospital Botucatu Clinics, all with 7.08% (n = 8). Regarding the character of patient care, urgency prevails with 64.60% (n = 73). The length of hospital stay of the patient after posterior thoraco-lumbosacral spine revision was 08 to 14 days (18.92%; n=14), and anteriorly was more than 30 days (15%; n = 03). The posterior cervical route was for 04 days, with 25% (n = 03), and 03 days (42.86%; n = 03) in the anterior route. There was a 3.54% (n = 4) postoperative death rate. In the expenditure per procedure, out of the total of R $ 324,294.50, the revisions of posterior thoraco-lumbosacral spine arthrodesis / treatment were 67.73% of the total, followed by 15.93% in the anterior approach, 8, 5% of revisions of posterior cervical spine arthrodesis, followed by 7.84% anteriorly. Conclusion: These events deserve attention from health authorities for their great impact on the quality of life of patients with pseudarthrosis, as well as economic. With this, strategies to decrease the rate of pseudarthrosis can be used posterior instrumentation to increase the rigidity of the construction.

1096

P282: Analysis of Spinal Tuberculosis Admissions in North Sumatra Main Tertiary Referral Hospital, Indonesia

Arya Cipta Widjaja ¹ , Pranajaya Dharma Kadar ¹ , Otman Siregar ¹ , Heru Rahmadhany ¹ , and Benny Lay ¹

¹ Faculty of Medicine Universitas Sumatera Utara, Orthopedic and Traumatology, Medan, Indonesia

Introduction: Owing the lack of available epidemiological data in Indonesia, we reviewed the recorded data of hospitalized admissions to our Orthopedic and Traumatology Department in Haji Adam Malik General Hospital, Medan – North Sumatra. We aimed at presenting a snapshot of the spinal Tuberculosis (TB) admissions to main tertiary referral center in North Sumatra and describing adapted management strategies based on this analysis for cost-efficient improvements, applicable to other countries facing similar epidemiological challenges. Material and Methods: Data was analyzed retrospectively based on the patient records of all admissions from January 2015 to December 2019 records that were admitted to Orthopedic and Traumatology Department in Haji Adam Malik General Hospital, Medan – North Sumatra, Indonesia. In 241 spinal TB admissions we recorded age, gender, comorbid, complications, level of lesion, and treatment modalities. Results: The median age was 26 years (range: 2 - 74 years) with a male-to-female ratio of 1 : 1.2. 10% patients were also attributed with HIV. Co-infection with HIV remained a major challenge for the effective treatment and control of tuberculosis. There were 164 patients (68%) who underwent spinal surgery for TB, with the most common lesion located in the thoracic spine (42% of cases). Numbness of the limb presented in 16% patients, being the most common sequelae of this spinal condition. Conclusion: In order to improve outcomes, appropriate and timely interventions in managing spinal TB before admissions have become a focus of our efforts. If goes undetected, spinal TB can be extremely severe, it can cause severe paralysis which may take years to get cured. Prompt and adequate treatment integrated with comprehensive examinations improve the outcomes of spinal Tuberculosis.

1584

P283: Spine Trauma in the Elderly: Increasing Incidence yet Decreasing Injury Severity

Catherine Carlile ¹ , Andrew Rees ² , Jacob Schultz ² , and Byron Stephens ²

¹ Vanderbilt University Medical Center, Nashville, USA

² Vanderbilt University School of Medicine, Nashville, USA

Background: With a rapidly increasing population of elderly patients, the characteristics of spine trauma in this group continues to evolve. Previous studies have shown an increasing incidence of spine trauma, but also decreasing mortality. We hypothesized that our level 1 trauma center’s prospective registry will reflect this trend. Methods: Retrospective chart review was completed for all elderly (65+) patients who presented with spine fractures from 2010-2019 at a single academic level I trauma center. Date of admission, location of injury, Injury Severity Scale (ISS), operative specifics if applicable, and long-term outcomes for patients were collected. Long-term trends were calculated and plotted for variables including number of patients, complications, and mortality at time intervals (in-hospital, 6-month, and 1-year). Goodness of fit testing was conducted to generate R2 values for each plot. Results: 1725 patients met inclusion criteria over the 9-year period. The number of elderly patients with spinal trauma increased ∼187% during that time period from 93 in 2010 to 267 in 2018. This trend was linear with a R2 value of .916. Average ISS on presentation decreased in a linear fashion with a R2 value of 0.9107. Rates of lasting neurological injury over time also decreased with an R2 value of .251. Medical and surgical complication rates showed a trend towards a linear decrease with a R2 value of .248. Mortality rates during admission, at 6 months, and at 1 year all decreased linearly with R2 values of .558, 0.8128, and .693 respectively. Conclusion: While the incidence of spinal trauma in the elderly has increased in our population, the average severity of those injuries has decreased. The underlying cause of these changes is likely multifactorial, including societal safety measures and a more active elderly cohort involved in low-energy trauma. These data suggest that policy and practice interventions aimed at reducing low-energy trauma (eg, ground-level falls) in the elderly could aid in controlling the growing incidence of spinal trauma in this population.

1718

P284: Spinal Disorders in Athletes Followed up at a Sports Trauma Center Over a 12 Year Period - Retrospective Study

Marcos Vaz de Lima ¹

¹ Santa Casa de São Paulo, Orthopedics, São Paulo, Brazil

Objective: To identify the most frequent spinal pathologies and in which sports are most common. Methods: A retrospective epidemiological study was carried out with data collection from medical records of the last 12 years in the sports trauma group at our institution. Results: 3000 medical records were analyzed, of which 296 were selected that met the inclusion criteria (spine disorder). The average age of the athletes was 26 years old and 52.7% were female. The most prevalent sports were ballet with 18.2%, gymnastics with 13.1%, fights with 11.3% and football with 9.1%. The main diagnosis was non-specific low back pain with 46.2% of cases. Imaging exams were not reported in 57.4% of patients, while physical therapy was indicated for 55% of cases. Conclusion: Nonspecific low back pain represented the highest percentage of all spinal disorders and ballet was the most prevalent modality.

Keywords

spine, athletes, epidemiology, backache.

1728

P285: Treatment of Acute Spinal Cord Injuries: Timing of Surgery - A Survey Among Ibero-Latinoamerican Spine Surgeons

Ana Ribau ^{1, 2} , Jorge Alves ³ , and Ricardo Rodrigues-Pinto ^{1, 2}

¹ Spinal Unit (UVM). Department of Orthopaedics. Centro Hospitalar Universitário do Porto., Porto, Portugal

² Instituto de Ciências Biomedicas Abel Salazar, Porto, Portugal

³ Centro Hospitalar do Tâmega e Sousa, Department of Orthopaedics, Penafiel, Portugal

Introduction: The ideal management of acute spinal cord injuries (ASCI) has been matter of long-lasting debate and investigation. While it is agreed that patients with acute injuries and instability need urgent surgical decompression, the ideal timing is not clearly defined. This is even more debated in the case of central cord syndrome without radiological evidence of instability but with spinal cord compression. The objective of this study was to evaluate the current practice in terms of timing of surgery in ASCI patients among spinal surgeons from Ibero-Latinoamerican countries. Material and Methods: A descriptive cross-sectional study design as a questionnaire was sent by an email, requesting to participate in a survey study for all members of SILACO and associated societies. IBM SPSS Statistics 24 was used for the statistical analysis. Results: One-hundred-sixty-two surgeons answered questions related to the timing for surgery. Sixty-eight (42.0%) considered that ASCI with complete neurology injury should be treated within 12 hours, 54 (33.3%) performed early decompression within 24 hours and 40 (24,7%) until the first 48 hours. Regarding acute SCI with incomplete neurological injury, 115 (71.0 %) would operate in the first12 hours. There was a significant difference in the proportion of surgeons that would operate ASCI within 24 hours or less, regarding the type of injury (complete injury:122 vs incomplete injury:155, P < .001) For 131 (80.9%) surgeons, the timing of the surgery was not affected by the anatomical region of injury. In the presence of patients with central cord syndrome without radiological evidence of instability but with spinal cord compression, 152 surgeons (93.8%) would perform surgical decompression: 1 (0.6%) in the first 12 hours, 63 (38.9%) in the first 24 hours, 4 (2.5%) in the first 48 hours, 66 (40.7%) in the initial hospital stay as soon as possible, 18 (11.1%) after neurologic stabilization (weeks or months after the trauma). Ten (6.2%) surgeons would not consider the surgical treatment regardless of its timing. Conclusion: All surgeons inquired in this survey favour early decompression in patients with ACSI, with the large majority performing surgery in the first 24 hours. Decompression is performed earlier in cases of incomplete than in complete injuries. In cases of central cord syndrome without radiological evidence of instability there is a tendency towards early surgical decompression but the timing is still extremely variable. Future studies are needed to identify the ideal timing for decompression of this subset of ASCI patients.

1734

P286: Recent Trends in Spinal Surgery Performed by American Board of Orthopaedic Surgery (ABOS) Part II Candidates (2008-2017)

Caleb Yeung ¹ , Andrew Schoenfeld ¹ , Harry Lightsey IV ¹ , James Kang ¹ , and Melvin Makhni ¹

¹ Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA

Introduction: The American Board of Orthopaedic Surgery (ABOS) Part II Oral Examination is typically taken 20 months following fellowship completion. Despite previous studies utilizing ABOS Part II Oral Examination data in other subspecialties, types of cases performed by spine surgeons in their first two years of independent practice has not been well-studied. Such data may help trainees anticipate case composition observed in early practice and allow spine fellowship programs to understand emerging trends. Material and Methods: We retrospectively reviewed surgical cases submitted to the ABOS by candidates taking the Part II Oral Examination between 2008-2017 whose designated subspecialty was spine. A hierarchical, restrictive algorithm was used to determine procedures based on candidate-reported International Classification of Diseases 9th/10th Revision and Current Procedural Terminology codes. Adjusted multivariable Poisson regression analyses were used to assess changes in procedure incidence rates over time. Results: We identified 37,539 cases, averaging 3,754 cases/year, and an average of 49 cases per candidate per six-month collection period. The most common procedures were lumbar discectomy (22% of all procedures), posterolateral spinal fusion (19%), and anterior cervical discectomy and fusion (17%). Rates of anterior cervical discectomy and fusion (ACDF) and cervical disc arthroplasty (CDA) significantly increased over time (incidence rate ratios [IRR] of 1.41 and 23.3 times higher, respectively, at the end of the study period), while rates of cervical foraminotomy, lumbar discectomy, posterolateral spinal fusion (PSF), and structural autograft use decreased (IRR of .35, .84, .55, and .30). Rates of anterior lumbar interbody fusion/lateral lumbar interbody fusion (ALIF/LLIF) and transforaminal lumbar interbody fusion (TLIF) did not significantly change over the study period. Conclusion: Recent spine fellowship graduates are performing more CDAs and ACDFs while decreasingly using structural autograft and performing fewer PSFs and lumbar discectomies. Techniques such as ALIF/LLIFs and TLIFs have not changed significantly over the last decade.

1902

P287: Future Activity Goals of Patients Considering Spine Surgery: A Pilot Study

Mustfa Manzur ¹ , Mark Fontana ² , Yahya Othman ² , Avani Vaishnav ² , Arjun Khoarna ² , Michelle Richardson ² , Han Jo Kim ² , James Farmer ² , Russel Huang ² , Sravisht Iyer ² , Harvinder Sandhu ² , Todd Albert ² , Catherine MacLean ² , and Sheeraz Qureshi ²

¹ Sidney Kimmel Medical College at Thomas Jefferson University, Philadelphia, USA

² Hospital for Special Surgery, New York, USA

Introduction: Patients are more likely to report higher satisfaction levels when able to return to the physical activities most important to them. An understanding of what specific physical activities are most important to spine surgery patients and the likelihood of returning to these physical activities has not been assessed previously in the literature. Material and Methods: Successive rounds of cognitive interviews with patients at our institution informed the development of a survey tool to measure patient goals with regard to their physical activities, current and future desired performance levels, current difficulty performing these physical activities, and time since the physical activities could last be performed at the desired performance level. This pilot survey was administered to new patients contemplating spine surgery over five consecutive weeks between May 2019 and July 2019. Responses were individually reviewed by their respective spine surgeon involved in the study (seven surgeons in total). Each surgeon recorded their agreement or modification for the physical activity goal(s) as well as the likelihood and anticipated timing for achievement. Commonality of physical activity goals, relationship of goals with patient demographics, and association of goals with current difficulty, modification, or lower anticipated chances of achievement were assessed for significant associations (P < .05). Results: During the study period, 176 patients were surveyed with 97.7% percent having one or more reported physical activity goals (213 total goals). Average patient age was 58.9 years (σ = 16.1, range: 19.0-93.0). Average patient BMI was 27.3 (σ = 5.3, range: 16.0-47.9). Of all patient activity goals, 28.4% involved a form of active exercise, 27.4% focused on walking exclusively, 15.8% included various recreational activities (non-golf), 11.6% were activities of daily living (ADLs), 9.3% were hobbies, and 7.4% involved golf. Female sex was associated with activity goals focused on both recreational activities (P = .036) and ADLs (P < .001). Higher age was associated with activity goals focused on exercise (P < .001). Higher BMI was associated with activity goals focused on both returning to activities of daily living (P = .011) and exercise (P < .001). Activity goals could be performed at a satisfactory level on average 3.2 years prior to screening (range: 0.0-28.0 years) with a longer period associated with higher BMI (P = .040). A shorter duration between screening and last being able to perform an activity goal was associated with two activity goals: ADLs (P = .001) and golf (P = .037). Surgeons suggested modification of 11.9% of patient activity goals, generally towards less intensity of activity, most frequently among lumbar spine surgery patients and associated with patients of higher BMI (P = .041). Anticipated achievement of physical activity goals, when deemed possible, was estimated to be 181.5 days on average (σ = 120.4, range: 42-730). Conclusion: Patient activity goals along with their anticipated likelihood and timing for achievement vary immensely. More than 20 patients from this pilot study cohort were identified to need activity goal modification after completion of the survey which reflects the importance of education and shared decision-making during the pre-surgical assessment and overall care planning processes when treating patients with spine conditions.

Imaging

159

P288: The Feasibility of Anterior Spinal Access - The Vascular Corridor at the L5-S1 Level for Anterior Lumbar Interbody Fusion

Julia Ng ¹ , and Jacob Oh ¹

¹ Tan Tock Seng Hospital, Orthopaedic Surgery, Singapore, Singapore

Introduction: The anterior lumbar interbody fusion (ALIF) offers many advantages for fusion at the L5-S1 junction. However, the variant iliac vasculature may preclude safe anterior access. This study aims to analyze the feasibility of anterior spinal access to the vascular corridor at the L5-S1 junction, by evaluating three crucial anatomical landmarks. This provides a framework for risk-stratification for the clinician during pre-operative evaluation. Materials and Methods: 500 MRI images of the L5-S1 level were identified, with 379 meeting inclusion criteria. We graded the anterior access into 3 grades, namely, easy, advanced or difficult by looking at 3 important anatomical landmarks – the vascular corridor (narrow if ≤ 25mm, medium if 25-35mm (inclusive), and wide if > 35mm), the left common iliac vein (LCIV) location (grades A-D based on the relative position of the LCIV to the L5-S1 disc space), and the presence or absence of a fat plane. Results: Our results showed that 43.27% of the patients had wide corridor for the anterior access, 19.26% of patients had no fat plane and 7.65% had a LCIV that extended past the midline of the disc (Grade C, D: > 50%). By combining these three factors, 37.20% would have easy anterior access, while a minority (1.85%) would have a difficult anterior access. Conclusion: The ALIF at L5-S1 offers significant benefits to the patient. The surgeon should be aware of the dangers in an anterior access by looking at three crucial factors to determine whether the access is easy, advanced or difficult. Patients with a difficult access should be attempted by experts, vascular access surgeons, or consider an alternative approach to L5-S1.

276

P289: Using the "Ligamentum Flavum Gap" to Identify Originally Missed Type B Vertebral Fractures

Alfredo Guiroy ¹ , Carlos Zanardi ² , Nelson Picard ² , Alfredo Sicoli ¹ , Ruben Morales Ciancio ¹ , and Asdrubal Falavigna ³

¹ Spanish Hospital, Orthopedics, Mendoza, Argentina

² Clinica La Pequeña Familia, Neurosurgery, Junin, Argentina

³ Caxias do Sul University, Neurosurgery, Caxias do Sul, Brazil

Introduction: Spine fractures may involve ligamentous injuries. The aim of our study was to assess radiological findings that may be useful for the direct diagnosis of lesions involving the posterior ligament complex (PLC) in the post acute scenario. Methods: Clinical files of patients with a late diagnosis of type B fractures between 2013 and 2016 were revised, with a special interest in imaging studies (flexion-extension X rays, dorsal decubitus X rays, CT scans and MRIs) addressing the PLC. Results: Ten patients with a delayed diagnosis of type B2 lesions were identified; 2 were at the cervical spine and 8 at the thoracolumbar area. All the patients complained of axial pain; four of them also evidenced progressive kyphosis deformity. Loss of continuity was identified in all the patients in the ligamentum flavum (LF) at the level of the lesion (“ligamentum flavum gap”), which was easier to see in the T2 weighted and STIR MRI sagittal sequences. Conclusion: In our case series we observed an MRI sign we named “ligamentum flavum gap”. This direct sign might be useful for the late diagnosis of type B lesions.

354

P290: Fully Navigated Pedicle Screw Placement in the Thoracolumbar Spine - An Evaluation of Intraoperative O-Arm Imaging

Josefin Aakerstedt ¹ , Lukas Bobinski ¹ , Przemek Kolakowski ² , Piotr Sliwinski ² , Marcin Jablonski ² , and Per Liv ³

¹ Spine Unit, Section of Orthopedics, Department of Surgical and Perioperative Sciences, Umeå, Sweden

² Umeå University Hospital, Spine Unit, Section of Orthopedics, Umeå, Sweden

³ Section of Sustainable Health, Department of Public Health and Clinical Medicine, Umeå, Sweden

Introduction: Image guidance and navigation has improved the accuracy and precision in instrumented spine surgery. The aim of this study was to investigate the precision of navigated screw placement in the thoracolumbar spine and to evaluate whether intraoperative images are of sufficient quality to supersede postoperative radiological control with computer tomography. Material and Methods: A prospective, single center study was carried out at the Spine Unit, Dept. of Orthopedics, Umeå University Hospital, Sweden. The study enrolled adult patients with spinal pathologies in the thoracolumbar spine undergoing instrumented surgery using posterior approaches, both; open, mini-open, and minimally invasive (MIS). All surgeries were performed using the O-arm^® integrated implant system with fully navigated pedicle screws. The evaluation of the intra- and postoperative images was performed by three spine surgeons as well as a neuroradiologist. Two different assessment protocols were used for the classification of pedicle screw positions: The 2D Gertzbein and 3D Abul-Kasim classification. Results: At this point the ongoing study includes 55 patients and is planned be completed at the end of 2020. 310 pedicle screws have so far been assessed and classified in a preliminary study showing an 99.0% agreement between the classification of neuroradiologist and surgeons of pedicle screws graded 0 to 1 in accordance with the Gertzbein classification. This corresponds to a 0- 2 mm cortical breach of the pedicle, and is viewed as good to acceptable positioning, with low risk of neurovascular complication. Out of the 310 screws only 10 screw i.e. <1 % (.968) were classified by neuroradiologist as grade 3 on postoperative DT, out of these only one of the surgeons classified one pedicle screw as a grade 3 (> 4 mm breaching of the pedicle) and the rest where by all surgeons classified as a grade two or lower. Although a breach of > 4 mm can potentially present a risk of neurovascular complications, there were no complications reported postoperatively and none of the patients underwent reoperation due to screw misplacement. The full evaluation of the study as well as the assessment using the 3D Abul-Kasim classification is ongoing. Conclusion: The evaluation of pedicle screw positions in intra- and postoperative imaging show high intraoperative precision and reliability. No significant difference was observed between the classification of screws from intra- and postoperative images. Hence, we conclude that pedicle screw positions can be reliably assessed from intraoperative imaging eliminating the need for postoperative radiological control. Furthermore, navigated pedicle screw placement in the thoracolumbar spine using the O-arm^® navigated system provides high precision that mitigates the risk of screw misplacement and thus intra- and postoperative complications as well as necessity for reoperation.

389

P291: Assessment of Thoracic Spine Intervertebral Disc Degeneration in Different Age Groups: An Analysis of Kinematic MRI Images of 1,000 Patients

Mohamed Mesregah ¹ , Michael Repajic ¹ , Kishan patel ¹ , Sidney Roberts ¹ , Carson Gardner ¹ , Zorica Buser ¹ , and Jeffrey C. Wang ¹

¹ Keck School of Medicine, University of Southern California, Department of Orthopaedic Surgery, Los Angeles, USA

Introduction: Intervertebral disc (IVD) degeneration is typically followed by progressive disc narrowing, osteophyte formation, and spinal stenosis. This study aimed to evaluate the age-related changes and distribution of IVD degeneration in different age groups using kinematic MRI (kMRI). Material and Methods: This cross-sectional study included 1000 symptomatic patients, who had undergone upright thoracic spine kMRI from January 2016 to August 2019. A total of 13000 thoracic IVDs from C7/T1 to T12/L1 were classified into five grades using Pfirrmann classification and T2-weighted sagittal images. Patients were divided into five groups, each of 200 patients, based on their ages. Group 1 included patients from 20 to 29 years, group 2 from 30 to 39 years, group 3 from 40 to 49 years, group 4 from 50 to 59 years, and group 5 consisted of patients aged 60 years and above. The severity and pattern of IVD degeneration were analyzed in each age group. A predictive analysis of the severity and pattern of IVD degeneration in each age group was proposed using multinomial logistic regression, using the delta method to calculate the average marginal effects. Results: Overall, 3683 (28.3%) IVDs were grade I, 3877 (29.8%) IVDs were grade II, 3802 (29.3%) IVDs were grade III, 1504 (11.6%) IVDs were grade IV, and 134 (1%) IVDs were grade V. The total grade of IVD degeneration and the number of degenerated levels increased with increasing age (P < .001). The most common degenerated level was T6/7 (13.3%), while the least common degenerated level was T12/L1 (1.8%). Single-level disc degeneration occurred in 109 (10.9%) patients, two-level disc degeneration in 79 (7.9%) patients, while 12 and 13-level disc degeneration occurred only in 5 (.5%), and 3 (.3%) patients, respectively. Adjacent-level degenerations were more common than skip lesions in patients with more than one-level IVD degeneration. Normal disc or mild disc degeneration could be predicted to occur more in group 1 (patients below 30 years) (margin = .53, 95% confidence interval (CI) = .46 to .59, P < .001). Moderate IVD degeneration could be predicted to occur more in group 2 and 3 (patients from 30 to 49 years) (margin = .42, 95% CI = .35 to .49, P < .001). Severe disc degeneration could be predicted to occur more in group 5 (patients with 60 years and above) (margin = .79, 95% CI = .73 to .84, P < .001), followed by group 4 (patients from 50 to 59 years) (margin = .57, 95% CI = .50 to .63, P < .001). Conclusion: The severity of IVD degeneration and the number of degenerated levels increased with age. Contiguous-level degeneration was more frequent than skip lesions in subjects with >2 levels of degeneration. Normal or mild disc degeneration could be predicted to occur more frequently in patients below 30 years, moderate IVD in patients from 30 to 49 years, and severe disc degeneration in patients above 60 years.

461

P292: Effectiveness of Three-Dimensional CT and MR Fusion Imaging for Full-Endoscopic Spine Surgery

Tsuyoshi Watanabe ¹ , Gakuji Gondo ¹ , Masahiko Tanaka ¹ , Takahiro Tanaka ¹ , Kazuko Hotta ¹

¹ Shonan Kamakura General Hospital, Neurosurgery, Kamakura city, Kanagawa, Japan

Introduction: Preoperative three-dimensional (3D) simulation has become increasingly significant since we performed full-endoscopic spine surgery (FESS) for lumbar disc herniation. Although 3D images, originally produced by a computed tomography (CT) scan, had an issue with accuracy of visualization of disc herniation and nerve roots, 3D fusion imaging that combines CT and magnetic resonance imaging (MRI) helped solve the issue and was useful in actual clinical practice. Here, we present the key points when producing and obtaining MRI and CT fusion 3D imaging. Material and Methods: A conventional CT imaging procedure for 3D images was used to produce bone images. 3D magnetic resonance myelography (MRM) with fine matrix size was performed to generate images of nerve roots, thecal sac, and disc herniation. Ziostation2 was used for 3D image processing. We examined if 3D fusion imaging is useful for choosing the appropriate approach (FESS via transforaminal or interlaminar approach) and performing preoperative simulations for each approach. Results: A difference in imaging procedures was an extended examination time (2 minutes and 30 seconds) required in 3D MRM. More realistic images were obtainable when the image of disc herniation and the distal part of nerve roots were created on the selected plane image that can be easily used to identify them. Image misalignment sometimes occurred during CT and MRI fusion. 3D fusion imaging was useful for choosing the appropriate operative approach and developing a surgical strategy. In the production of 3D fusion imaging, an increased burden of an MRI room and a patient was an examination time extended by 2 minutes and 30 seconds. Image misalignment during CT and MRI fusion was caused by alteration of spine alignment which occurred due to patient position during an imaging examination; however, the issue was fully solved by the following efforts made during a CT scan: Flex the elbow and immobilize it against the anterior chest region without elevating both upper extremities; Obtain CT images during voluntary breathing without holding the breath; and Use the same cushion when a CT scan is performed during the hip and knee flexion. Conclusion: 3D CT and MRI fusion imaging can be produced only by adding some extra examination time. This 3D fusion imaging is therefore useful in preoperative simulation for FESS.

463

P293: Independent Inter and Intraobserver Agreement Analysis of a New Classification of Sacroiliac Joint Degeneration

Julio Urrutia Escobar ¹ , Gaston Camino Willhuber ² , Matias Borensztein ³ , Osvaldo Velan ³ , Nelson Astur ⁴ , Marcelo Alejandro Valacco ⁵ , and Pablo Cikutovic ⁶

¹ Pontificia Universidad Católica de Chile, Departamento Traumatología y Ortopedia, Santiago, Chile

² Hospital Italiano de Buenos Aires, Institute of Orthopedics “Carlos E. Ottolenghi,” Hospital Italiano de Buenos Aires, Ciudad Autónoma de Buenos Aires, Argentina

³ Hospital Italiano de Buenos Aires, Servicio de Diagnóstico por imágenes, Ciudad Autónoma de Buenos Aires, Argentina

⁴ Hospital Israelita Albert Einstein, San Pablo, Brazil

⁵ Hospital Churruca Visca, Ciudad Autónoma de Buenos Aires, Argentina

⁶ Pontifica Universidad Católica de Chile, Departamento de Radiología y Diagnóstico por Imágenes, Santiago, Chile

Introduction: Sacroiliac joint degeneration is considered a source of low back pain. Recently, Eno et al developed a tomographic classification of degeneration based on tomographic changes. The objective of this study was to assess an external validation of this classification. We performed an independent inter- and intra-observer agreement assessment applying the Eno classification of sacroiliac joint (SIJ) degeneration and evaluating the presence of gas in the SIJ. Material and Methods: We studied 64 patients ≥60 years old who were studied with abdominal and pelvic computed tomography scans. Six physicians (three spine specialists and three radiologists) from three centers in Latin America evaluated axial images to grade SIJ degeneration into grade 0 (normal), grade 1 (mild degenerative changes), grade 2 (significant degeneration), and grade 3 (ankylosis). We also evaluated the agreement assessing the presence of gas in the SIJ. After a 4-week interval, the 64 cases were presented to the same assessors in a random sequence for repeat evaluation. We used the weighted kappa coefficient (wk) to determine the agreement. Results: The inter-observer agreement was moderate (wκ = .50 [.44-.56]), without differences among surgeons (wκ = .53 [.45-.61]) and radiologists (wκ = .49 [.42-.57]). The agreement evaluating the presence of gas was also moderate (κ = .45 [.35-.54]), but radiologists obtained better agreement (κ = .61 [.48-.72]) than surgeons (κ= .29 [.18-.39]). The intra-observer agreement using the classification was substantial (w κ = .79 [.76-.82]), without differences comparing surgeons (wκ = .75 [.70-.80]) and radiologists (wκ = .83 [.79-.87]). The intra-rater agreement evaluating gas was substantial (κ = .77 [.72-.82]), without difference between surgeons (κ = .71 [.63-.78]) and radiologists (κ = .84 [.78-.90]). Conclusion: Our independent panel obtained a moderate inter-observer agreement and a substantial intra-observer agreement using the Eno classification; we also observed a moderate inter-observer agreement and a substantial intra-observer agreement evaluating the presence of gas.

505

P294: Concordance of Imaging Findings in Facet Joint Pathology by Comparing MRI and SPECT/CT of the Lumbar Spine

Fernando Alvarado Gómez ¹ , Andres Rodriguez Munera ¹ , Luis Carlos Morales Saenz ¹ , Pedro Pablo Gaviria ¹ , Jose Rafael Dangond Milian ¹ , Jorge Uribe Medina ¹ , and Yuli Viviana Fuentes Barreiro ¹

¹ Hospital Universitario Fundación Santa Fe de Bogotá, Bogotá, Colombia

Introduction: Determining facet osteoarthritis as the primary source of pain in low back pain is a challenge for the clinician, especially due to the limited guidance provided by the physical examination and imaging tests. The aim of this study is to compare the concordance of the findings of the magnetic resonance imaging and the bone scan with SPECT / CT, in an analytical way to determine the clinical relevance of these findings. Material and Methods: A cross-sectional analytical study was carried out in 80 patients with a diagnosis of lumbar pain who had a SPECT / CT scan, computed tomography present in this scan and magnetic resonance imaging of the lumbar spine. Data were classified according to the classifications of Pahtria in 1987, Weishaupt in 1999, and the level with uptake in scintigraphy. The statistical tests used were Kappa de Fleiss, Factorial of correspondence; and the Cocharn and McNemar test. Results: When performing the statistical analysis with the Cocharn and McNemar test, it was found that between L1-L3 there were no significant differences between the positive results diagnosed between the resonance vs tomography, however, there were significant differences between the diagnostic results of the scintigraphy vs tomography and scintigraphy vs resonance in this location (P < .01). At the L3-S1 level, there were significant differences when comparing the results of the 3 studies (P < .01). Conclusions: There is a difference between the diagnostic results obtained by scintigraphy vs tomography and resonance. Requesting this complementary test increases the probability of detecting diseased levels that do not yet show structural anatomical changes, but if they endure inflammatory processes that cause pain.

517

P295: CT Osteoabsorbptiometry Assessment of Subchondral Bone Density Predicts Intervertebral Subsidence in a Human Cadaveric Model

Alejandro Espinoza Orias ¹ , Evan Sheha ¹ , Paul John ¹ , Ashlyn Fitch ¹ , Howard An ¹ , Nozomu Inoue ¹ , Matthew Colman ¹ , and Zavras Athan ¹

¹ Rush University Medical Center, Orthopedic Surgery, Chicago, USA

Introduction: Subchondral bone mineral density (SBD) has been shown to reflect the long-term distribution of stress acting on the joints and can be used to evaluate the onset and progression of endplate degeneration. There are important advantages when using a 3-dimensional (3-D) method to evaluate SBD. Computed tomography osteoabsorbptiometry (CT-OAM) based on a standard fine-cut CT scan is an emerging open source software technique to perform 3D analysis of SBD. As an example, this technique has the ability to record differences in density distribution of certain regions of the endplate, with emphasis on subchondral bone. The purpose of this study was to measure the subchondral bone mineral density of the cervical endplates by using CT-OAM and correlate it to subsidence in a cadaveric model. Materials and Methods: Fourteen (7F, 7M, age range 27-89 y.o.) cadaveric cervical spines were used in this study. All specimens (n = 8 C4-5, n = 6 C6-7 motion segments) were potted in polymethylmethacrylate (PMMA), instrumented with standalone PEEK interbody spacers, and subjected to a dynamic testing regimen: five compressive ramp loading preconditioning cycles from 50 to 250 N at a frequency of .5 Hz, followed by a compressive sinusoidal load spanning the same load range at 2 Hz for 10,000 cycles. All specimens were imaged with clinical CT at .625 mm thickness slices (no spacing) three times: 1^st) whole intact cervical spine, 2^nd) before the test (potted and instrumented), and 3^rd) immediately after completion of the mechanical testing (still instrumented). These images were used to assess the bone mineral density distributions using CT-OAM in a region of interest directly underneath the spacer. The CT-OAM analysis was carried out in .5 mm intervals down to a depth of 3.0 mm beneath the endplate surface. Subsidence was defined based on the displacement values at peak loads (both 250N) on cycles no. 1 and no. 10,000; and the difference between these points in the displacement axis was the measured deformation of the endplate in mm. SBD data was presented in g/cc. Results are presented as mean ± SD. Significance was set at P = .05. Results: The observed “failure mode” was consistently recorded as subsidence, where the interbody spacer indented itself into the endplates. Mean subsidence by level was registered as .45 ± .36 mm and .40 ± .18 mm, for C4-5 and C6-7, respectively, without differences by level. Deformation (subsidence) as a function of SBD: The experimental cyclic test showed that denser endplates experienced less deformation under the same load than less dense ones. Conclusions: This study showed that the regions with higher CT-OAM values experienced less subsidence and validated the use of CT-OAM as a method to evaluate the endplate SBD. While subsidence is a multi-factorial event that is still poorly understood in relation to the endplate tissue structure-function relationships, work like this is providing new tools to clinicians treating spinal conditions in need of augmentation and stabilization via interbody devices. The CT-OAM method is easily translated to the clinic, has been validated in many other joints, and does not require additional tests or cost to the patient.

622

P296: Morphological Analysis of Paraspinal Muscles Using Magnetic Resonance Imaging and a Novel Software to Diagnose Sarcopenia

Balagurunathan Durairaju ¹ , Shanmuganathan Rajasekaran ¹ , Dilip Chand Raja Soundararajan ¹ , Ajoy P Shetty ¹ , and Rishi Kanna ¹

¹ Ganga Medical Centre and Hospitals Pvt Ltd, Spine Surgery, Coimbatore, India

Introduction: Sarcopenia is defined as age associated loss of skeletal muscle mass and function. There is a scarcity of literature in assessing the Sarcopenia of lumbar paraspinal muscle and its association with age in Indian population. Our aim was to determine the age and sex dependent lumbar paraspinal muscle morphology in Indian population. Materials and Methods: The objectives of this study were To calculate the mean of morphological variables such as Total Cross Sectional Area (TCSA), Relative Cross Sectional Area (RCSA), Functional Cross Sectional Area (FCSA), Percentage of Fat Infiltration (FI%) and their asymmetry between right and left side in multifidus, erector spinae and psoas major muscle in different sex and age group of Indian population using MRI. To identify the normal trend of lumbar paraspinal muscle degeneration due to ageing. To find the association between BMI and FI% of paraspinal muscles. Study population was divided into six groups based on age. Results: Total number of samples included in the study was 210, (98 females and 112 males), with a mean age of 38.8 ± 15.04 years. The mean height was 162 ± 8.14 cm and mean weight of 65.85 ± 11.17kgs with a mean BMI of 25 ± 3.82. Statistically significant asymmetry was found between Left and Right side of TCSA of psoas muscle (P = .022), FCSA of psoas muscle (P = .001), TCSA of erector spinae (P = .014), FCSA of Multifidus (P = .001). However FCSA of erector spinae and TCSA of Multifidus did not show significant asymmetry between the Left and Right side (P = .072 and P = .983 respectively). On considering the Fat Infiltration Percentage Psoas and Multifidus muscle showed statistically significant asymmetry (P = .006 and P = .001 respectively) unlike Erector spinae (P = .341). Psoas muscle Total Cross Sectional Area, Functional Cross Sectional Area, and Fat Infiltration Percentage showed statistically significant correlation (P = .020, P = .008, and P = .016 respectively) with BMI. Erector spinae had the larger TCSA followed by Psoas and the Multifidus had the least TCSA in all age group. TCSA of Erector spinae had increasing trend in early decades and had decreasing trend in the late decades of life. However TCSA of Psoas and Multifidus did not showed significant trend. The Multifidus muscle degenerated significantly at higher rate, than the erector spinae muscle. Psoas degenerated at lower rate on comparing to other paraspinal muscles. Conclusion: Digital analysis of MRI images with ImageJ software serves as an ideal tool to investigate morphological feature of paraspinal muscle. Normative value of paraspinal muscle morphology will be useful to investigate other spinal pathologies. Paraspinal muscle degenerates more qualitatively rather than quantitatively. Females had higher degeneration rate than males. Although there was an asymmetry between paraspinal muscle morphology, the difference is less. Thus we have to be cautious while considering asymmetry in spinal musculature as a cause of spinal pathology. Like osteoporosis, sarcopenia of paraspinal muscle will determine the late life disability. MRI could be used as a reliable stand alone investigation tool to assess Sarcopenia and related disorders.

643

P297: Is the Implant in Bone? The Accuracy of CT and Fluoroscopic Imaging for Detecting Malpositioned Pelvic Screw and SI Fusion Implants

Jose San Miguel-Ruiz ¹ , Jonathan N. Sembrano ¹ , Takashi Takahashi ² , Melissa Albersheim ¹ , Paul Lender ¹ , David Polly ^{1 3} , and Christopher Martin ¹

¹ University of Minnesota, Department of Orthopaedic Surgery, Minneapolis, USA

² University of Minnesota, Department of Radiology, Minneapolis, USA

³ University of Minnesota, Department of Neurosurgery, Minneapolis, USA

Introduction: S2-Alar-Iliac (S2AI) pelvic fixation has been widely used following long fusions to the sacrum. More recently, surgeons have begun performing open fusion of the sacroiliac (SI) joint at the time of long fusions to the sacrum with the use of triangular titanium rods (TTR). In an optimal technique, the TTR implant starts in the lateral sacrum proximal to the S2AI screw, crosses the SI joint, and then remains contained within the upper portion of the bony tables of the ilium for its entire length. Previous studies have shown that fluoroscopic imaging is limited in its ability to detect certain types of cortical breaches when placing pelvic screws. However, it is not known how effective fluoroscopic or CT based modalities are at detecting misplaced SI fusion implants. Material and Methods: S2AI Screws were placed into a sawbones model in one of the following positions: (1) optimal anatomic placement, (2) violation of the sciatic notch, (3) hip joint violation, (4) medial wall violation, and (5) lateral wall violation. We then obtained AP, Lateral, Inlet, Outlet, Iliac Oblique, and Teardrop fluoroscopic views of each specimen, and followed this with a CT scan. Next, TTR were placed above the S2AI implants in the same specimens one of the following positions: (1) Optimal anatomic position, (2) medial wall violation, (3) lateral wall violation, (3) superior violation. The imaging was then repeated. Lastly, we then removed the S2AI implants, and imaged the TTR implants alone. In all cases, the breached implant extended from the cortical margin by approximately 5mm. The images were then randomized and two independent radiographic reviewers who were not involved in the surgical implantation reported their interpretation of which implant, if any was breached, and if so in which location. We then compared the reviewer’s interpretation of the images against the known implant breaches to determine the accuracy of each imaging modality in identifying implant breaches. A kappa statistic was calculated to determine the correlation between the reviewer’s interpretation and the actual implant positions. Results: When asked to determine the presence of a cortical breach using the complete set of fluoroscopic images, the reviewers’ kappa value was .641 (.344 - .923, P < .001), consistent with moderate agreement with the master key. In comparison, determination of the presence of cortical breach using the CT based images yielded a kappa value of .906 (.646 - 1.0, P < .001), consistent with an almost perfect agreement with the master key. Conclusion: The detection of a breached pelvic implant is improved with intra-operative CT compared to fluoroscopy alone. Surgeons may consider obtaining intra-operative CT scans in order to verify optimal implant placement following long spinal fusions to the pelvis with concomitant SI joint fusion using TTR.

717

P298: Clinical Utility of a Spinal Cord Shape Classification System (SCSCS) in Spinal Deformity Surgery

Griffin Baum ¹ , Meghan Cerpa ² , Alex Sielatycki ² , Earl Thuet ² , Joseph Osorio ³ , Richard Menger ⁴ , Wenbo Lin ² , Simon Morr ² , Ronald A. Lehman ² , and Lawrence Lenke ²

¹ Northwell Health, New York, USA

² Columbia University Medical Center, New York, USA

³ University of California San Diego, San Diego, USA

⁴ University of Alabama, Mobile, USA

Hypothesis: There will be a high rate (k>/ = .4) of reliability and reproducibility for a clinically useful apical spinal cord shape classification system (SCSCS). Design: Observational. Introduction: Loss of IONM data during spinal deformity correction can occur in up to 27% of cases. The Spinal Cord Shape classification system (SCSCS) based on axial MRI cuts has been shown to correlate with loss of IONM data during surgical correction with a 34x OR. We examined the reliability, reproducibility and clinical utility of this SCSCS in a consecutive series of spinal deformity patients. Methods: Patients who had spinal deformity correction with complete IONM reports and preoperative total spine MRI between July 2015 and December 2017 were included. An axial T2 image was taken from the apex of the deformity with the following 3 SCSCS types: 1. CSF present between SC and apical pedicle/body; 2. No CSF present between apical pedicle/body and normal cord shape; 3. Altered SC shape due to pressing against apical body/pedicle. These MRI axial images were shown to 12 spine surgeons on two different days to select the SCSCS type (1-3). Ratings were registered in the database and analysis was performed using Fleiss’ Kappa in the R statistical analysis software. Results: 139 apical MRI images were rated by 12 different surgeons on 2 days. The total interrater reliability for the SCSCS was k = .72 (P < .001), and intrarater reproducibility was k = .77 (P < .001), both showing excellent agreement. Conclusion: An apical spinal cord shape classification system (SCSCS) is extremely reliable (k = .72), and reproducible (k = .77), and helps predict clinically significant loss of neuromonitoring data (OR = 34) in patients undergoing spinal deformity correction.

732

P299: C2 Pedicle Sclerosis Grading, More Than Just Diameter, Predicts Surgeons' Assessment of Safe Screw Placement: A Novel Classification System

Erika Chiapparelli ¹ , Ichiro Okano ¹ , Stephan Salzmann ¹ , Marie-jacqueline Reisener ¹ , Sohrab Virk ¹ , Fabian Winter ¹ , Jennifer Shue ¹ , Andrew Sama ¹ , Frank Cammisa ¹ , Federico Girardi ¹ , and Alexander Hughes ¹

¹ Hospital for Special Surgery, NY, USA

Introduction: The preoperative assessment of C2 morphology is important for safe instrumentation. Previous studies proposed that certain anatomical parameters such as the width of the pedicle can be used to evaluate the safety margin and risk of a lateral breach with C2 pedicle screw insertion. However, no study has evaluated whether other anatomical factors should be considered. Additionally, local sclerotic changes are often seen in C2 pedicles and quantitative diameter measurements may not be accurate in these cases. The main objectives of this study are: (1) propose a novel grading system of the C2 pedicle and (2) compare the predictive value of this grading system and diametrical pedicle measurements with the surgeon’s safety evaluation. Material and Methods: We retrospectively reviewed 220 cervical CTAs at a single academic care institution. C2 pedicle outer width, pedicle inner width on an axial plane parallel to the pedicle trajectory, pedicle maximum height, and pedicle minimum height on the sagittal reconstruction images were measured. We utilized a novel grading system of the C2 pedicle that consisted of a width measurement on the axial image and the degree of sclerosis in the pedicle (type I: ≥4mm width no sclerosis, type II: ≥4mm width <50% sclerosis, type III: ≥4mm width >50% sclerosis, type IV: ≥4mm width completely sclerotic, and type V: <4mm width regardless of sclerosis). Two board-certified orthopedic spine surgeons reviewed identical CTA slices for each patient and classified their assessment of safe screw placement into: 1) safe (minimal risk of VA injury), 2) caution needed (screw inserted with caution to minimize VA injury), or 3) dangerous (high risk of VA injury with screw insertion). We compared the diagnostic value of the morphological measurements and sclerosis grading to the surgeons’ safety assessment as “Low risk” (safe or caution needed) and “High risk” (at least one classified as dangerous) groups. We conducted the receiver operational characteristic (ROC) curve analysis to compare the areas under the curve (AUC) to determined cut-off points between classification types. We also evaluated inter/intra-rater agreement using a random selection of 98 pedicles. Results: A total of 411 pedicles of 203 patients (mean age 69.5, 49.5% female) were included. 241 C2 pedicles were considered safe/caution needed for screw insertion and classified as the low risk group. The remaining 170 C2 pedicles were considered unsafe for screw insertion and classified as the high risk group. The high risk group consistently had smaller diametrical measurements (all P < .001) and higher grades based on the grading system (P < .001). Among the measured parameters, the sclerotic grade showed the best predictive value. For the cutoff between the type III and IV and V sclerosis classification, the sensitivity and specificity for high risk screw placement was 83.5% (77.1-88.8) and 88.8% (84.1-93.5), respectively. Conclusion: We introduced a novel tool to evaluate safety of C2 pedicle screw placement. Results suggest that our pedicle width sclerotic grading system is highly reproducible and better predicts surgeon’s assessment of safe screw placement than C2 pedicle diametrical measurements alone.

835

P300: Image Quality Comparison Between Traditional "Stitched" and 2D Long Film O-arm images

Bryan Ladd ¹ , Kristen Jones ² , Christopher Martin ³ , and David Polly ²

¹ University of Minnesota, Neurosurgery, Minneapolis, USA

² University of Minnesota, Neurosurgery, Orthopedic Surgery, Minneapolis, USA

³ University of Minnesota, Orthopedic Surgery, Minneapolis, USA

Background: Intraoperative imaging of long constructs for spinal deformity is typically performed via a manually “stitched” method using a sequence of consecutive images. This can be accomplished using an intraoperative CT or C-arm. However, the quality of the images can suffer from variable penetration and x-ray scatter over the length of the construct and are exposed to human error during the manual “stitching” process. An upgrade for the Medtronic O-arm now includes “2D Long Film” functionality that automatically acquires long films to address this problem. Materials and Methods: After the software and hardware upgrade was applied, the new technology was used during the next three scheduled spinal deformity cases at the University of Minnesota. All patients obtained preoperative EOS, intraoperative manually “stitched”, and 2D Long Film images for comparison. These cases constituted the first clinical application of this new imaging technology. Results: The 2D Long Film images provided higher quality images of the construct and interbody implants for more accurate assessment of the deformity correction and instrumentation placement, while removing a possible source of human error, which comes with manual “stitching”. The contrast was especially apparent in patients with a high BMI. No difference in overall image processing time was noted. Data provided by Medtronic claims the 2D Long Film technology decreases radiation exposure when compared to the manually “stitched” method. Conclusion: The new 2D Long Film functionality on the Medtronic O-arm automates an important step in spinal deformity surgery, without impacting case duration, and claims to decrease radiation exposure.

1064

P301: Morphology of Intervertebral Discs and Vertebral Bodies During Growth

Steven de Reuver ¹ , Lorenzo Costa ¹ , Hanna van Rheenen ¹ , Moyo Kruyt ¹ , Marijn van Stralen ² , and René Castelein ¹

¹ University Medical Center Utrecht, Department of Orthopedic Surgery, Utrecht, The Netherlands

² University Medical Center Utrecht, Imaging Division, Utrecht, The Netherlands

Introduction: Radiography studies have reported that height growth of the spine is located predominantly in the vertebral bodies. However the contribution (if any) and behavior of the intervertebral discs during this process remains fairly unknown. Recent studies showed the importance of the intervertebral disc in the etiology of adolescent idiopathic scoliosis (AIS). Furthermore, idiopathic scoliosis develops predominantly in otherwise healthy females in early adolescence. Our hypothesis is that in the general population, intervertebral disc morphology of adolescent females is different than in males. The purpose of this study is to provide an accurate map of the 3D morphology of intervertebral discs and vertebral bodies during growth in asymptomatic children and adolescents. Material and Methods: 298 patients aged 0-21 years that have received CT-scanning for indications not related to the spine were included. Custom made software for semi-automatic imaging analysis was used to analyze each vertebral body upper and lower endplate in the exact mid-sagittal plane, corrected for orientation in all three planes. The surface area and centroid of all endplates were automatically determined. The intervertebral disc was defined as the space between two adjacent endplates of the vertebrae above and below the disc. The height of discs and bodies was defined as the distance between two adjacent endplate centroids. Height, transverse surface area, volume and their interrelated ratios for different sex and year of age were calculated. Results: For the thoracic spine, the vertebral height increased throughout growth from 6.3 ± .7mm to 20.3 ± 1.4mm, while the intervertebral disc height increased only from 3.5 ± .4mm to 4.9 ± .6mm at age 4, whereafter it remained stable during the remaining growth. In the lumbar spine, vertebral body height increased from 9.0 ± .6 mm to 27.7 ± 1.9mm and there was a slight but constant height increase of the lumbar intervertebral disc from 4.4 ± 0.4mm to 9.0 ± 1.6mm. Height increase of thoracic vertebral bodies was .70mm/year in males and 0.62mm/year in females(P = .001). The transverse surface area of intervertebral discs increased throughout growth from 68 ± 14mm² to 184 ± 27mm² in the thoracic spine, was 14-25 mm² larger in males(P = .018), and increased from 85 ± 34mm² to 285 ± 54mm² in the lumbar spine. The slenderness of thoracic intervertebral discs (height divided by surface area and normalized to 100 at age 0) decreased from 100 ± 21 to 45 ± 11, and was +7 more slender in females throughout growth(P = .039). Age plots showed that the largest differences between male and female disc morphology occurred at age 9 to 14 years. Conclusion: Height increase of the spine during growth is located predominantly in the vertebral bodies and was more pronounced in the thoracic spines of males. Intervertebral discs remained largely similar after the first years of growth. The transverse surface area of intervertebral disc increases throughout the whole growth and is greater in males. The slenderness of intervertebral discs decreases throughout growth and, especially at early adolescence, the thoracic discs of females are more slender. These observations, together with earlier growth-spurt timing, could explain part of the higher prevalence of AIS in females, with intervertebral disc slenderness being a risk-factor, even before AIS onset.

1068

P302: Can Diffusion Tensor Imaging Add Information to Aid Decision-Making in the Management of Cauda Equina Syndrome? A Review of the Current Literature

Harin Wijayathunga ¹ , Vithanage N. Wijayathunga ² , Ruth Wilcox ² , Ryckie Wade ³ , Peter Loughenbury ³ , Matthew Marzetti ³ , Steven Tanner ⁴ , John Ridgway ⁴ , and Almas Khan ³

¹ University of Edinburgh Medical School, Edinburgh, United Kingdom

² Institute of Medical and Biological Engineering, School of Mechanical Engineering, Leeds, United Kingdom

³ Leeds Teaching Hospitals NHS Trust, Leeds, United Kingdom

⁴ University of Leeds School of Medicine, Leeds, United Kingdom

Introduction: Cauda equina syndrome (CES) is a life changing surgical emergency caused by acute compression of the sacral nerve roots, disrupting motor and sensory function of the perineum. It is diagnosed by standard MRI to identify morphological changes and nerve root compression. In neural tissue water diffuses anisotropically. Nerve compression causes nerve root oedema, demyelination, axonal damage and blockage to nerve vascular and axoplasmic flow. This widens the space between axons and myelin sheaths, increasing radial diffusivity and reducing axial diffusivity. Diffusion tensor imaging (DTI) evaluates this physiological behaviour and Fibre-Tractography (FT) can demonstrate gross fiber architecture. We reviewed the current use of DTI and how it might be applicable in the clinical management of CES. Material and Methods: A literature search was conducted on the EMBASE and PUBMED databases. The search terms ‘Cauda Equina Syndrome’ AND ‘Diffusion Tensor Imaging’ (where ‘AND’ is a Boolean operator) produced zero relevant articles, so the search criteria were expanded to ‘Diffusion Tensor Imaging’ AND each of the following terms: ‘Lumbar Nerve/ Sacral Nerve/ Lumbosacral Nerve/ Spinal Nerve/ Disc Herniation’. Articles involving human participants were selected, categorised, and analysed based on the application of DTI. Results: Of the 76 articles identified from the search, 47 were deemed relevant to the research question. None of these outlined use of DTI for the clinical management of CES; one described the post-surgical treatment/management of a non-CES spinal nerve pathology; one characterised the diagnosis of a non-CES lumbar nerve pathology; and the remaining 45 were methodological development and feasibility studies on the application of DTI on spinal nerve pathologies. 27 articles reported significantly lower fractional anisotropy (FA) values of the nerves on the symptomatic side/subject, and 32 articles reported distinct FT abnormalities in the symptomatic nerve tracts. Fewer studies mentioned the apparent diffusion coefficient (ADC); though out of the 14 that did, 10 reported elevated ADC values in nerve-pathologies (or lower values post treatment). Conclusion: DTI with FT may be able to define intact and locate damaged nerve pathways, thus can play a role in prognostication and clinical decision making in CES but has so far not been reported in the literature. As an emerging technique, the majority of the work on spinal nerve DTI, to-date, describes the development, optimisation and validation of its application to nerve pathologies. Acquiring DTI is complex, and lengthy post-acquisition processing may be needed, which limits its translation to clinical practice. However, DTI represents a potentially powerful and objective tool to supplement the diagnosis of CES and monitor postoperative nerve recovery.

1101

P303: Assessment of Pedicle Screw Malposition in Uniplanar Versus Multiplanar Spinal Deformities in Children

Kailash Sarathy ¹ , Sarang Rokade ¹ , Arjun Dhawale ² , Siddharth Badve ³ , Kshitij Chaudhary ⁴ , Rujuta Mehta ¹ , Alaric Aroojis ¹ , and Abhay Nene ¹

¹ B.J. Wadia Hospital for Children, Orthopaedics, Mumbai, India

² Sir H.N Reliance Foundation Hospital and B.J. Wadia Hospital for Children, Mumbai, India

³ Musculoskeletal Institute, Geisinger Health, Orthopaedics, Lewistown, India

⁴ Sir H.N. Reliance Foundation Hospital, Orthopaedics, Mumbai, India

Introduction: Spinal deformities can either be uniplanar or multiplanar. The nature of the deformity may make radiographic assessment of misplaced pedicle screw placement more challenging. Purpose of this study is to compare malpositioned pedicle screw assessment on radiographs versus CT in children <12 years with multiplanar and uniplanar spinal deformities. Material and Methods: Single center, retrospective, comparative study, level of evidence 3. 16 Children, mean age 10.1 years, who underwent posterior spinal fusion using free-hand pedicle screw insertion for multiplanar (M) or uniplanar (U) deformities with post- operative radiograph and CT evaluation of 162 screws. The primary outcomes measure included the assessment of malpositions detected on plain radiographs versus CT scans in U and M deformities. The secondary outcome measures included neurovascular complications and revision surgeries. The overall breaches in post-operative plain radiographs and CT in each group were compared and analyzed by two independent observers. The mal-positioned screws were graded on extent of cortical breach. Inter and intra-observer variability was calculated with Kappa(k) method. Chi-square test, unpaired t test were used for analysis. Sensitivity, Specificity and Positive Predictive Value (PPV) and Negative Predictive Value (NPV) were calculated by comparing breaches on radiographs versus CT. Results: 162 pedicle screws were analyzed, 73 in U group and 89 in M group. The groups were similar with respect to age, gender and number of levels fused (P > .05). There were 25 (15.4%) malpositioned screws identified on plain radiographs and 43 (26.5%) on CT (P = .013). Among the 43 CT breaches, 12/73 (16.43 %) were in U group, 31/89 (34.83 %) were in M group, (P = .01) of which 10/162(6.17%) were Grade III, 2/73 (2.73%) in U group and 8/89 (8.9%) in M group, (P value = .18). The overall Sensitivity, Specificity and PPV of plain radiographs compared to CT in detecting malpositions were 32.56%, 90.76% and 56% respectively. In U group, Sensitivity was 27 50%, specificity was 95.08% while PPV and NPV were 66.67% and 90.62%. In M group, Sensitivity was 25.81%, specificity was 86.21% while PPV and NPV were 50% and 68.49 %. The intra and inter-observer variability had excellent correlation. Conclusion: There was a significant discrepancy in identification of pedicle screw malposition based on plain radiographic versus CT based assessment more so in multiplanar deformities. The ability to detect a breach on plain radiographs is lesser in multiplanar versus uniplanar deformities.

1135

P304: Inflammatory Spondyloarthropathy as a Cause of Chronic Low Back Pain Should Always be Considered

Balamurugan Thirugnanam ¹ and Apoorv Agarwal ¹

¹ Manipal Hospitals, Spine Care, Bengaluru, India

Introduction: Chronic low back pain is a common reason for seeking medical attention and obtaining an MRI scan. Inflammatory spondyloarthropathy is an under-diagnosed cause of chronic low back pain leading to prolonged suffering and numerous visits to hospitals. The aim of this study was to ascertain the prevalence of sacroiliitis, which is an early indicator of inflammatory spondyloarthropathy, among patients who present with chronic low back pain. Materials and Methods: Two hundred consecutive lumbosacral spine MRI scans performed at Manipal Hospital, Bangalore were analysed by two radiologists and a spine fellow. The demographic data of the patients and the presence of sacroiliitis and other abnormalities on the scans were noted. Results: Among the 200 patients included in the study, 119 were male and 81 were female with a mean age of 35.07 years. 31 (15.5%) patients were diagnosed to have sacroiliitis which included 14 males (11.76%) and 17 females (20.99%). Conclusion: The study showed that 15.5% of patients who presented with low back pain had sacroiliitis which is more than previously reported. Thus, it is important to carefully assess the sacroiliac joints of low backache patients both clinically and radiologically, so that the diagnosis is not missed and appropriate treatment can be given.

1155

P305: Detection of Vertebral Body Fractures. Comparison Between Conventional Radiography and EOS Imaging

Carolin Melcher ¹ , Vanessa Pfahler ² , Andrea Baur-Melnyk ³ , Robert Stahl ² , and Christof Birkenmaier ⁴

¹ University Hospital Ulm, Department of Orthopedic Surgery (RKU), Ulm, Germany

² University Hospital LMU Munich, Campus Großhadern, Department of Radiology, München, Germany

³ University Hospital LMU Munich, Campus Großhadern, Department of Radiology, Munich, Germany

⁴ University Hospital LMU Munich, Campus Großhadern, Department of Orthopedic Surgery, Physical Medicine and Rehabilitation, München, Germany

Introduction: Diagnostic Imaging procedures performed to answer a specific clinical question frequently result in additional questions and hence in further imaging, mostly by use of other modalities as the preceding study. At the same time, each additional radiological study performed entails additional radiation exposure for the patient. With CR, a vertebral body fracture (VBF) is seen and a regional CT scan is performed to better understand the specific characteristics of that VBF. With the VBF being classified as stable, a full-spine film is ordered to properly assess spinopelvic balance which can be critical in further therapeutic decision-making. At that point, the question arises, whether the initial CR could have been avoided. This question is of even greater interest, when a low-dose imaging option such as an EOS 2D/3D® system (EOS) is available for full spine imaging. Material and Methods: A database search of the PACS / RIS system of a University Radiology Department was performed in order to identify patients as of July 2015 who had undergone EOS® imaging of the spine or the whole body and Conventional radiography of the spine within a time window of 3 months. The search yielded 213 eligible patients. Postoperative examinations as well as incomplete conventional imaging (thoracic spine or 1 plane only) were eliminated and 79 patients finally included. The identified images were pseudonymized and independently evaluated by 2 experienced orthopedic spine surgeons in consensus. A total of 1100 vertebrae per imaging modality were subjected to a categorical visual assessment as well as semiquantitative and quantitative evaluation according to the Genant classification plus a combination of the above. Whenever multiple fractures were detected, the most severely fractured vertebra was determined by semi-quantitative and quantitative measurement in each modality. Results: Surprisingly, CR remarkably underperformed as compared to EOS in sufficiently visualizing vertebrae at and above the Th10 level, with 25,6 % of vertebrae being considered unreadable. Overall at least one vertebral body fracture was detected in 51/79 patients (65%) by means of CR and in 57 patients using EOS. Concordant identification between the 2 modalities was observed in 50 patients (88%), whereas in 12% of VBF, these were only identified in one of the 2 modalities. 6 VBF were detected with EOS only, whereas only 1 VBF was detected with CR but not with EOS. Having a closer look on the per- vertebrae distribution high specificity was found throughout the lumbar spine to detect a fracture ≥ grade 1 whereas sensitivity was low. Given multiple fractures, the majority of the identified most severe fractured vertebrae occurred in the thoraco-lumbar junction (TH 11-L1) with 33/51 (70%) in CR and 31/57 (57%) in EOS followed by the lumbar spine. Conclusion: Fracture detection as well as quantitative fracture assessment was reliable with both, CR and EOS and showed high concordance between the techniques. However, EOS appears to be more sensitive than CR, especially in the thoracic spine, which might be partly due to its orthogonal fan beams moving perpendicular to the imaging target reducing image distortion and its greater greyscale dynamics.

1175

P306: Reliability of Digital Radiological Measurements in Thoracolumbar Trauma: Radiography and Computed Tomography Validation

Oscar Bravo ¹ , Ignacio ACuña ¹ , Álvaro Soteres ¹ , Jaime Cancino ¹ , Pedro Lizama ¹ , Guillermo Izquierdo ¹ , Felipe Novoa ¹ , and Manuel Valencia Carrasco ¹

¹ Hospital Clinico Mutual de Seguridad, Santiago, Chile

Introduction: Imaging studies are fundamental in the diagnosis and treatment of spinal trauma, currently all trauma centers have digital systems. These programs have tools that allow specific measurements to classify these lesions and define their treatment, but there is not enough scientific evidence of digital measurements reliability. The aim of this study is to determine the intra-interobserver reliability of digital radiography (X-ray) and computed tomography (CT) measurements in thoracolumbar spine fractures. Material and Methods: We performed an observational reliability study. 30 full spine X-rays and 30 CTs of patients with vertebral fractures were randomized and stratified by thoracic, thoracolumbar and lumbar segments. Images were independently analyzed by five evaluators with different expertise level in two sessions using XERO Viewer (Agfa HealthCare) program. Regional kyphosis (RK), segmental kyphosis (SK), vertebral kyphosis (VK) and percentage of vertebral collapse (PVC) were measured. Evaluators were blind to measurement subject and randomization sequence. StataSE 14.0 program was used to obtain intrainterobserver Intraclass Correlation Coefficients (ICC) according to two-way randommixed effects model, respectively. Results: The interobserver ICCs were “excellent” (RK .986, SK .965, VK .9440, PVC .968 in CT and RK .8882, SK .984, VK .965, PVC .979 in X-ray) as well as the average of intraobserver ICCs for all measurements (RK .990, SK .985, VK .986, PVC .955 in CT and RK .996, SK .985, VK .984, PVC .977 in X-ray), independent of the study and level of expertise. Conclusion: Sagittal deformity measurements using digital tools in radiographs and computed tomography of patients with vertebral fractures are reliable and reproducible. The intra and inter observer reliability is excellent independently of the evaluator expertise.

1217

P307: Ossification of the Ring Apophysis in Normal Pediatric Population

Lorenzo Costa ¹ , Moyo Kruyt ¹ , and René Castelein ¹

¹ UMCU, Utrecht, The Netherlands

Introduction: The ring apophysis is a thin, cartilaginous mound that encircles the borders of the inferior and superior surfaces of the vertebral bodies. As part of skeletal maturation, these rings mineralize during growth and ultimately fuse to the vertebral bodies. The assessment of maturity of the spine is essential in management of children with spinal deformity. Most papers that have described maturation of the ring apophysis are rather old and based on observations on plain x-Rays. The aim of this study is to define a pattern of each thoracic and lumbar ring apophyses in normal, non-scoliotic pediatric population on CT images. Ultimate goal is to extrapolate the CT findings to Bone MRI, a new technology that enables CT-like images extracted from MRI data. MRI is part of general work up in many patients with scoliosis. Material and Methods: We systematically searched for high-resolution computed tomography scans including the thoracic and lumbar spine from T1 to S1, of subjects between 6 and 21 years of age. Scans were taken for reasons unrelated to this study. Multi-planar reconstructions of each vertebra were acquired. The ossification and fusion of the anterior and posterior part of the superior and inferior rings were scored on the mid-sagittal image, whereas the lateral parts of the rings were scored on the mid-coronal image. A total of eight points were per vertebral body were screened (four for the superior ring and four for the inferior ring). Stage 0 means the ring is still not ossified and not detectable in all the four points on CTs. In stage 1 the ring starts to ossify. Stage 2 indicates ossification in all four corners, but no fusion is detectable. In stage 3 the ring is fused to the vertebral body in one, two or three areas. In stage 4 the ring is fused to the vertebral body in all four areas. Differences between ages, gender and spine levels were detected. Results: In the sagittal plane ossification starts around the age of 7, the fusion starts at 13 and the fusion ends between 16 and 21 years of age. In the coronal plane the ossification starts later, around 10-12, the fusion starts around 14-16 and it ends around 19-21 years of age. The superior ring fuses faster than the lower one but the ossification starts earlier. The fusion is completed approximately 1 year earlier in females than in males. Lastly, the rings between T6-T12 in males and between T5-L3 in females fuse later than the other sections. Conclusion: It was possible to define a pattern of the ossification and fusion of the ring apophysis and make a classification out of the findings.

1251

P308: Evaluation of Spinal Fusion on Standard X-Rays: A New Grading System for Spinal Interbody Fusion

Nirmal Patil ¹ , Hussein El Ghait ² , Christian Boehm ³ , and Heinrich Boehm ¹

¹ Zentralklinik, Spine surgery, Bad Berka, Germany

² Al-Azhar hospital, Spine surgery, Cairo, Egypt

³ ETH, Department of Earth Sciences, Zurich, Switzerland

Introduction: Bony fusion of vertebrae is the main goal of spinal surgery worldwide. Therefore, one would expect that many established and consented methods exist for proofing treatment success. However, this is not the case and open exploration is still regarded as the gold standard. Conventional radiographs have been studied extensively for evaluation of postero-lateral fusions but not for interbody fusion surgeries. Since several authors found sensitivity at 89%, specificity at 60% and correlations to surgical exploration in the range of 45 - 69% for predicting solid fusion, it was concluded, that plain x-ray is not adequate to assess fusion status. Thus fine-cut axial and multiplanar CT reconstruction views were widely advocated as the method of choice not only for posterior but as well for anterior fusion of the lumbar spine. This superiority of CT based evaluation of fusion status might not be justified. Some authors even conclude that CT overestimates fusion. Above from costs and requirements of infrastructure it would seem unethical to apply radiation of whatever kind after a clinically uneventful course in a relatively pain free patient just for confirmation of bony union. The goal of this work is to analyse the time course and stages, establish a threshold time for spinal interbody fusion and to analyse whether routine follow-up radiographs are sufficient for assessment of the process of bony union. Methods: Sequential lateral radiographs of 238 patients (313 levels) with interbody fusion operated thoracoscopically were analysed. The inclusion criteria were interbody fusion surgeries and a final follow-up evidence of radiological bony healing (minimum of 1 year). Each author independently evaluated every follow-up radiograph according to a newly developed classification system for assessing bony fusion. Results: Evaluation of 1696 radiographs with a mean follow-up of 65.19 months and average numbers of 5.42 (2-18) images per level could be done. Diagnoses were Pyogenic Spondylitis (74), Fracture (96), Ankylosing Spondylitis (38) and Degenerative Disease (105). At final follow-up the optimum fusion state = Grade 0 was detected in 185 levels, solid, but less complete = grade 1 in 53, grade 2 in 40, grade 3 in 24, grade 4 in 0, and grade 5 (failure) in 11. No case with grade 2 deteriorated to grade 5. On average, grade 4 persisted for 113 days, grade 3 for 197 days, grade 2 for 286 days and grade 1 for 316 days. The first 95% of levels (“Green zone”, ≤ grade 2) fused at 1 year, the remaining 4% levels fused between 12 and 17 months (“Yellow zone”) and the last 1% (“Red zone”) fused after 510 days. The kappa coefficient for the inter-rater agreement was 0.91 ± 0.02 and for the intra-rater agreement ranged from .85 to .93. Conclusion: Sequential lateral radiographs permit evaluation of interbody fusion. Grade 2 is the threshold point for fusion; once accomplished, failure is unlikely. If fusion (Grade 2,1 or 0) is not reached until 510 days, it should be regarded as failed. The 510-day-threshold could reduce the necessity of CT scanning for assessing fusion.

1395

P309: Sacro-Pelvic Anthropometry in the Portuguese Population and its Implication for Screw Placement in Spinal Surgery: A CT-Based Study

Catarina Pereira ^{1, 2} , André Maçães ² , Carolina Luísa Lemos ^{2, 3} , and Ricardo Rodrigues-Pinto ^{1, 2}

¹ Spinal Unit (UVM). Centro Hospitalar Universitário do Porto. Portugal, Orthopaedics, Porto, Portugal

² Instituto de Ciências Biomédicas Abel Salazar, Porto, Portugal

³ Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal

Introduction: The sacrum is the target of lumbosacropelvic instrumentation in fractures, deformities and instabilities. These surgical interventions require detailed knowledge of the anatomy of the sacrum. Also, there are no anatomic references in sacropelvic trajectories for screw placement in the Portuguese population. The aim of this study was to assess the sacropelvic anthropometry in the Portuguese population, through the study of pelvic CT scans. Material and Methods: Forty individuals pelvic CT scans were analyzed and measurements were performed according to predefined screw trajectories of S1 anterior (S1A), anterolateral (S1AL) and anteromedial (S1AM), S2 anterolateral (S2AL) and anteromedial (S2AM), S2 alar iliac (S2AI), iliac and sacroiliac (SI) screws. For each trajectory, length and angles were measured and comparisons between genders were made. Results: The S1A screw trajectory mean length was 30,80 ± 3,31mm. The S1AL screw trajectory mean length and lateral angle were 36,48 ± 5,39mm and 33,13° ± 6,06, respectively, and the S1AM´s were 46,23 ± 3,36mm and 33,21° ± 3,86. The S2AL screw trajectory mean length was 28,66 ± 2,46mm and mean lateral angle was 26,52° ± 3,31 and the S2AM were 29,99 ± 4,05mm and 33,61° ± 3,53. The S2 alar iliac mean length, lateral and caudal angles were 125,84 ± 8,19mm, 36,78° ± 3,27 and 28,66° ± 5,78, respectively. The iliac screw mean length, lateral and caudal angles were 136,73 ± 8,75mm, 23,86° ± 3,00 and 24,01° ± 5,34, respectively. The sacroiliac screw trajectory mean length was 75,50 ± 4,75mm. Additionally, with regard to gender analysis, the length of the screws was longer in men than in women, except for the S1A and SI screws, in which there were no differences between genders. Conclusion: This study describes sacropelvic anatomical specifications. These defined morphometric details should be taken into consideration during surgical procedures.

1408

P310: Spinal Cord Medial Safe Zone During c2 Pedicle Instrumentation: a MRI Measurement Analysis

Erika Chiapparelli ¹ , Edward Bowen ¹ , Ichiro Okano ¹ , Stephan Salzmann ¹ , Marie-jacqueline Reisener ¹ , Jennifer Shue ¹ , Andrew Sama ¹ , Frank Cammisa ¹ , Federico Girardi ¹ , and Alexander Hughes ¹

¹ Hospital for Special Surgery, NY, USA

Introduction: Intraoperative spinal cord injury during upper cervical spine surgery is a rare, but potentially life-threatening complication. Patients with pathological conditions such as congenital malformations, inflammatory diseases, and degenerative diseases especially may have altered anatomy that can increase the risk of spinal cord injury during instrumentation. Pre-operative planning for C2 screw placement typically focuses on the bony dimensions of the C2 pedicle on CT and the location of the vertebral artery. However, few studies have evaluated spinal cord safety margins in the upper cervical spine. The purpose of this study is to investigate the spinal cord safety margins for C2 instrumentation. Material and Methods: This study was approved by our hospital’s institutional review board. We retrospectively reviewed the preoperative cervical MRIs performed for any clinical indication between 2009 and 2018 at a single academic institution. The distances between the C2 pedicle’s inner cortex and the dura (P-D) as well as between the pedicle and the spinal cord (P-SC) on an axial plane parallel to the pedicle trajectory, were measured bilaterally (Figure 1). We also measured the C1 lateral mass to spinal cord (LM-SC) distance bilaterally in the same plane. We defined the distances above the typical cervical screw diameter (4mm) as safe for instrumentation. To assess inter-observer reliability of the measurements, another independent rater measured 20 randomly selected patients, and to assess intra-observer reliability, the same 20 patients were re-measured by the same rater 6 weeks later. All statistical analyses were performed utilizing R software (R for 3.5.2 GUI 1.64). The statistical significance level was set at P < .05. Results: A total of 146 patients (mean age 71.2, 50.7% female) were included. The average distances were 5.5 mm for the C2 left P-D, 5.9 mm for the C2 right P-D, 10.1 mm for the C2 left P-SC and 10.6 mm for the C2 right P-SC. 28 (21.4%) patients had C2 P-D distances under 4mm. Regarding the C2 P-SC distances, all of the patients had measurements above 4 mm (Table 1). There were significantly more female patients with C2 P-D distances under 4 mm compared to male patients (male 8/72, 11.1%, female 20/74, 29.4%) (P < .05) (Table 2). Age was not a significant factor affecting distances. The interclass correlation coefficient for the Intra/inter-observer agreement for the measurements were good to excellent for all measurements (inter-rater C2 P-D .855, P-SC .844 and intra-rater C2 P-D .995, P-SC .995). Conclusion: In this study, we demonstrated that no patients had a C2 P-SC distance below 4mm. Approximately 20% of patients had a C2 P-D distance below 4 mm. Our results suggest that a spinal cord injury from a C2 pedicle screw is highly unlikely. Considering lateral misplacement might lead to a potentially fatal vertebral artery injury, medial screw insertion is almost always recommended for C2 pedicle screw insertion. This study investigated the safety margins of the spinal cord during C2 pedicle screw insertion and found that spinal cord injury from a C2 pedicle medial screw insertion is highly unlikely. This information will help surgeons perform the surgery safely.

1713

P311: A comprehensive MRI Analysis of Paraspinal and Psoas Muscle Size, Lean Muscle, and Fatty Infiltration in Patients Undergoing Lumbar Fusion

Stephan Salzmann ¹ , Ichiro Okano ¹ , Ek Tsoon Tan ¹ , Oliver Sax ¹ , Erika Chiapparelli ¹ , Marie-Jacqueline Reisener ¹ , Jennifer Shue ¹ , Federico Girardi ¹ , Frank Cammisa ¹ , Andrew Sama ¹ , Darryl Sneag ¹ , and Alexander Hughes ¹

¹ Hospital for Special Surgery, New York, USA

Introduction: The paraspinal muscles have an important stabilizing function. Atrophy and fatty infiltration of these muscles have been associated with increased age and various spinal pathologies. Comprehensive data of lumbar paraspinal muscle size/fatty infiltration in patients undergoing spine surgery is limited. The objective of this study was to (1) assess the reliability of a manual segmentation protocol to measure paraspinal muscle size/fatty infiltration, (2) determine possible variation in muscle measurements throughout the lumbar spine and (3) assess the correlation between percentage of fat-free muscle of the levels L1-S1. Material and Methods: Patients undergoing posterior fusion with available preoperative lumbar MRI were included. Muscle measurements were performed at the inferior L1 endplate, superior/inferior L2-5 and the superior S1 endplate. Using a free software program, we manually defined the following 4 regions of interest per slice on T2-weighted axial images: left/right psoas, and left/right posterior muscles (combined erector spinae/multifidus). Muscle measurements included the total cross-sectional area (CSA), percentage of fat-free muscle and the functional cross-sectional area (FCSA) (area of muscle isolated from fat). The FCSA was calculated with a custom written Matlab™ program, which identified pixels as either muscle or fat by selecting an automatic threshold signal following intensity bias correction by quadratic fitting. Pixel values below the threshold were classified as muscle and pixels above as fat. To assess inter-observer reliability of the manual segmentation, a validation study was performed. Pairwise comparison of CSA/percentage of fat-free muscle was conducted and correlations between each level/location were evaluated. Results: The study population consisted of 21 men and 29 women (86% Caucasian). The mean age was 62 years and the mean BMI was 30.2 kg/m². The inter-rater reliability for the measurement of the CSA and the FCSA was excellent (ICC of .975 and .961, respectively). Overall, the percentage of fat-free muscle was significantly higher in the psoas compared to the posterior muscles (92.0% vs 57.7%, P < .001). Men demonstrated higher posterior muscle CSA and percentage of fat-free muscle compared to women (60.4% vs 55.6%, P < .001). While men also had higher CSA of the psoas, there was no difference in percentage of fat-free muscle between men and women (91.9% vs 92.1%, P = .727). Overall the CSA of the psoas was highest at the inferior endplate of L4 and decreased in cranial and caudal directions. The percentage of fat-free muscle was over 90% for the psoas at all levels. In contrast, the posterior muscles FCSA was highest at L1 and decreased in the caudal direction, with almost 50% fatty infiltration at L5/S1. Despite level-dependent differences in percentage of lean muscle, significant correlations among all measured levels were observed within the same muscle group (Pearson’s correlation coefficient .43-.97). Multivariate analysis revealed that age, female sex, BMI and lower lumbar levels were associated with decreased lean muscle and increased fatty infiltration of the paraspinal/psoas muscles. Conclusion: This study provides comprehensive level-specific muscle data in a large cohort of patients undergoing spine surgery. There is significant variation in muscle size/fatty infiltration depending on muscle group, anatomical level and demographic factors.

1720

P312: Roentgenographic Evaluation of the Spine in Patients With Osteogenesis Imperfecta

Marcos Vaz De Lima ¹ and Claudio Santili ¹

¹ Santa Casa de São Paulo, São Paulo, Brazil

Introduction: Osteogenesis imperfecta (OI) is a hereditary connective tissue disorder that leads to bone weakness and deformities, especially in the spine, which can lead to poor outcomes. The aim of this study was to find patterns and risk factors in spinal deformities in patients with OI. Material and Methods: In a retrospective study, 70 patients with OI were selected. Radio- graphs of the spine were evaluated. We observed the presence or absence of the following changes: biconcave vertebrae, chest and vertebral deformities, unilateral rib, and thoracolumbar kyphosis. The greater curve was considered the primary one, and the secondary curve considered compensatory. Results: In the study sample, we observed that the patients’ ages ranged between 7 and 50 years, with a mean equal to 13 years, and 76% had scoliosis. In 68% of cases the main curve in the thoracic region was observed with the convexity to the right. Conclusion: The following was found in patients with OI: scoliosis, biconcave vertebrae, vertebral and chest deformity, unilateral rib, and thoraco- lumbar kyphosis. The thoracolumbar kyphosis is highly associated with thoracic hypokyphosis in patients with OI.

Infections

105

P313: Bone Cement as an Alternative to Inter-Somatic Cage in Management of Lumbar Spondylodiscitis

Hesham El Saghir ¹ and Walid El Nawawy ¹

¹ Alexandria University hospitals, Orthopaedics, Alexandria, Egypt

Introduction: Postoperative spine infections (PSIs) are a dangerous complication of spine surgery. Usually PSIs are treated through antibiotic therapy with early bracing or bed rest, but sometimes a more aggressive surgical treatment is required. The Concept of surgical treatment is adequate debridement, decompression of the compressed neural tissues, stabilization of the affected segment plus support and restoration of the anterior column to restore the coronal and sagittal profile. This can be done through different techniques ranging from a single posterior approach or anterior approach to a combined posterior and anterior approach using bone graft with or without cages^(3-5). Our study objective is to assess the results of debridement, pedicular fixation plus using inter-somatic bone cement through single dorsal approach in cases of spondylodiscitis. Material and Methods: seven patients suffering from postoperative spinal infection (PSI). All underwent debridement, pedicular fixation and interbody fusion using local autogenous bone graft and inter-somatic antibiotic-impregnated bone cement via posterior approach. The minimum follow-up period was two years. Clinical outcome was assessed by the criteria of Kirkaldy-Willis. Results: Kirkaldy-Willis functional outcome showed excellent results in four patients and good in three patients. Bony union in front of the cement was achieved between six and nine months after the surgery in all patients. Cement-bone interface became indistinguishable during the follow-up period in six patients. Local deformity was corrected and maintained during the follow up period. Conclusion: Posterior lumbar interbody fusion using inter-somatic bone cement with autogenous bone graft can be a good alternative in some cases of pyogenic spondylodiscitis or instability resulted from spondylodiscitis where cement provides structural support and may provide local release of antibiotics.

127

P314: Evaluation of Staphylococcus Aureus and Candida Albicans Biofilms Adherence to PEEK and Titanium-Alloy Prosthetic Spine Devices

Luiz Gustavo Dal Oglio da Rocha ¹ , Felipe Tuon ² , and Victoria Tasca Ribeiro ²

¹ Cajuru Hospital, Spine surgery, Curitiba, Brazil, ² Cajuru Hospital, Infectology, Curitiba, Brazil

Introduction: Titanium and polyether-ether-ketone (PEEK) interbody cages are commonly used for spine fusion. Few data are known about bacterial and yeast biofilms formation in these implants. The aim of this study was to compare Staphylococcus aureus and Candida albicans biofilm formation in the surface of two different interbody devices used routinely in spine surgery. Material and Methods: Six bodies of proof specimens of PEEK and titanium-alloy were used for microbiological tests, scanning electron microscopy, and energy dispersive X-Ray spectroscopy. Experimental biofilm was produced with Staphylococcus aureus and Candida albicans, followed by quantitative analysis of planktonic cells and sessile cells. The comparison between the medians of biofilm quantification between the two models was performed using the Mann-Whitney test and considered the statistical difference for a P < .05. Results: In the S. aureus model, in both planktonic and sessile cell counts, titanium alloy samples showed lower values for colony forming units per milliliter (UFC/mL) (P < .05). The evaluation through the optic density of planktonic and sessile cells showed lower values in the titanium-alloy samples; however, only statistically significant in planktonic cell count (P < .05). The count of planktonic yeast cells in PEEK was similar with titanium-alloy samples, while the count of sessile yeast cells in titanium-alloy was lower when compared to PEEK (P < .05). Conclusion: Titanium-alloy models were associated with less staphylococcal and Candida biofilm formation when compared with PEEK.

210

P315: Morphological Classification of Pyogenic Spinal Epidural Abscess

Pedro Bazán ¹ , Alfredo Godoy Adaro ² , Nicolas Ciccioli ³ , Jose Soria Adamo ⁴ , and Richard Avero Gonzalez ⁵

¹ HIGA San Martín - Hospital Italiano La Plata, Spinal Unit, La Plata, Argentina

² Clinica Modelo Paraná, Parana, Argentina

³ Clinica Pueyrredon, Spinal Unit, Mar del Plata, Argentina

⁴ Clinica Francesa, Spinal Unit, Mendoza, Argentina

⁵ Sanatorio Modelo de Quilmes, Quilmes, Argentina

Introduction: Pyogenic Spinal Epidural Abscess (PSEA) is the location of an infectious collection within the spinal canal, difficult to diagnose and with devastating consequences. Its most feared complication is neurological deficit due to vascular compression or compromise. Initial diagnosis depends on the suspicion, based on the clinical symptoms and laboratory tests. Magnetic Resonance Imaging (MRI) presents high sensitivity and specificity in the diagnosis, enhanced if contrast media is used. Literature presents several classifications of vertebral infectious processes, with emphasis on spondylodiscitis, where PSEA is included, but its extension or intra compartmental location is not analyzed. Objectives: present a new morphological classification of the spinal epidural abscess; analyze inter- and intra-observer reproducibility; discriminate the different parameters; analyze the different resonance images. Material and Methods: On the basis of an image database, a morphological classification focused on the PSEA has been planned. This classification uses 5 parameters: Region (R) marking the upper and lower limits of the abscess; Location (L), anterior or posterior within the canal; Compromise (C), meningeal or content of the structures; Association (A), discitis, osteomyelitis or both; and Perivertebral (P), anterior, lateral or posterior extravertebral abscess. The first three parameters give an idea of the volume of the PSEA and the last two the related infectious foci. 35 cases are analyzed on three different occasions, to use the Kappa coefficient. Results: The global intra- and inter-observer reproducibility is Kappa 0.81; analyzing each parameter is: R = .95, L = .92, C = .66, A = .70 and P = .80. The first three parameters give a notion of volume and the last two relate to the presence of vein infectious foci outside the canal. MRI in T2 with contrast was the most effective. Conclusion: The proposed morphological classification is simple to use with an excellent intra- and inter-observer reproductive rate. The parameters with the highest reproducibility are: region and location with values >.92 and the rest between .66 and .80. The addition of gadolinium contrast enhances the sensitivity of the diagnosis; the use of sagittal and axial images in T2 is more sensitive for classification. In the immediate future, it is necessary to expand the number of cases and re-evaluate the reproducibility of the classification and associate it with clinical parameters to make a scale that justifies therapeutic indications.

264

P316: Efficacy of the Tricortical Autologous Bone-Graft vs MESH Cage to Correct Kyphosis in Thoracolumbar Spinal Tuberculosis Treatment Through Posterior Approach

Ghanshyam Kakadiya ¹

¹ Topiwala National Medical College & Nair Hospital, Orthopaedics, Mumbai, India

Introduction: Spinal tuberculosis is a one of the most common and dangerous forms of tuberculosis. In advanced stages it causes destruction of the spinal column that can result in kyphotic deformity and neurological deficit. Vertebral height restoration is quite demanding and changing during the surgery for postoperative better clino-functional outcomes. The study aim was to compare the efficacy of tricortical bone graft and titanium mesh cages to restore vertebral height through posterior approach in patients with thoracolumbar spinal tuberculosis. Material and Methods: 98 thoracolumbar spinal tuberculosis patients operated with posterior decompression and fusion surgery were retrospectively included in this study. Group-A had 48 patients and operated with autologous iliac crest bone graft for interbody fusion to restore vertebral height. Group-B had 50 patients operated with titanium mesh interbody fusion. Both groups subdivided as per number of vertebral level involvement. Demographic data, surgical variables, VAS, ODI, CRO, ESR, neurological function recovery, bony fusion, intervertebral height, Cobb angle and postoperative complications recorded and analysed. Results: Mean follow-up time was 25.5 months. All patients were completely recovered and obtained solid bone fusion. The bony fusion time was 8.7 ± 3.6 months in group-A and 9.4 ± 6.1 months in Group-B. The Cobb correction and restoration of intervertebral height significantly improved compared with those in preoperative, but without significant difference among both groups (P > .05). The loss of kyphosis correction and intervertebral height in group-A were found to be more than group-B (P < .05). In addition, neurological function was revealed to be significantly improved after surgery. There were significant differences of VAS, ODI, ESR and CRP between preoperative and postoperative at the final follow-up time (P < .05), with no significant difference among both groups (P > .05). No statistically significant difference was found when analysing blood loss, hospital stays, hospitalization expenses, and corrective cost among three groups (P > .05). Complications included CSF leakage (4 cases in group-B), sinus formation (3 cases sinus formation in each group and 2-cases of abscess reformation in group-A. No implant failure was found in any patient. Conclusion: Titanium mesh cages could obtain good clinical efficacy comparable to autologous tricortical bone graft when treating single-level and multilevel spinal tuberculosis.

267

P317: Clinical Outcome of the Type-II Odenoid Fracture Treatment: Anterior Cannulated Screws Fixation vs Posterior Instrumentation of C1-C2 Without Vision

Ghanshyam Kakadiya ¹

¹ Topiwala National Medical College & BYL Nair Hospital, Department of Orthopaedics, Mumbai, India

Introduction: The excellent outcomes of temporary fixation of C1-2 without fusion in the treatment of odontoid fracture had been reported in recent literature. It is still unclear if this technique could achieve the equivalent outcomes as the golden standard technique of anterior screw fixation. The objective of this study is to compare the clinical outcome of two treatments of fresh type II odontoid fracture: anterior cannulated screws fixation (ACSF) versus posterior instrumentation of C1-2 without fusion (PIWF). Material and Methods: We retrospectively included 14 males and 5 females, and the mean age was 41.6 years (range, 22 to 57 years). Six patients were treated with ACSF, and 13 patients with PIWF. For PIWF, the implants were removed after fracture union was confirmed at .75∼1.5 years later. All patients underwent preoperative and serial postoperative clinical examinations at approximately 3 months, 6 months, and annually thereafter. The neck disability index (NDI) was used to assess the neck discomfort caused by the operation. The range of rotary motion was evaluated at each visit. All fractures were reassessed postoperatively with serial radiographs and CT-scans of the cervical spine at each follow-up visit, to evaluate screw position, fracture alignment, and fusion status. Results: All patients achieved immediate spinal stabilization after surgery, and none experienced neurologic deterioration. The follow-up periods ranged from 24 to 36 months. The average range of neck rotation was dramatically lost in PIWF after fixation (46° and 89° respectively in ACSF and PIWF), and recovered to 83° after the implant was removed. The NDI in PIWF was statistically higher than that in ACSF (5 and 13% respectively in ACSF and PIWF) after the first operation and decreased to 8% 1 year after the secondary operation. The fusion rates were 90.9 and 96% respectively in ACSF and PIWF. Both groups had a case of fracture non-union. Conclusion: For fresh type II odontoid fractures, a high rate of fracture union can be achieved by both ACSF and PIWF. For most fresh type II odontoid fractures, anterior screw fixation was the best option for its simplicity and preservation of normal atlantoaxial rotary function. Posterior instrumentation without fusion could preserve most of the atlantoaxial rotary function and lead to moderate neck discomfort and is also a good alternative if anterior screw fixation is contraindicated.

382

P318: Outcome Analysis of Sub Axial Cervical Spine Tuberculosis Treated by Anterior Debridement and Uninstrumented Fusion: A Single Centre Experience

Sudhir Srivastava ¹ , Aditya Raj ¹ , and Nandan Marathe ²

¹ Seth G.S Medical College & K.E.M Hospital, Orthopaedic, Mumbai, India

² Toronto Western Hospital, Toronto, Canada

Introduction: Cervical spine tuberculosis is a relatively uncommon manifestation of spinal tuberculosis. The number of patients are still significantly higher in endemic countries where a substantial number of patients show osseoarticular manifestations. This disease carries potential for extensive vertebral destruction and resultant risk of neurological compromise. Anterior plating of the cervical spine can also be associated with plate related complications in upto 10% of the cases. This study aims to find out the radiological and functional outcome of patients treated with anterior debridement and bone grafting without instrumentation for subaxial cervical tuberculosis. Methods: This study was conducted at a tertiary care hospital. Patient data was retrospectively evaluated from January 2009 to December 2017. Demographic data and radiological records of patients with sub axial cervical spine tuberculosis (C3-C7) were analyzed retrospectively. Patients who required surgical intervention in the form of anterior debridement and isolated bone grafting without instrumentation were included in the study. We restrict the use of stand alone bone grafting to patients where the total anterior reconstruction required is upto one vertebral body or less. Patients who were managed conservatively alone or those who required additional posterior instrumentation were excluded from the study. Patients with posterior element involvement, multi centric involvement in spine, cervico-thoracic involvement and previously operated cases were also excluded from the study. The clinical parameters included the Visual Analogue Score (VAS) for neck pain and the neurological involvement as per the ASIA grade. Standard radiological investigations including plain radiographs and Magnetic resonance imaging (MRI) of the cervical spine were done at the time of presentation. Kyphosis at the time of presentation, immediately after surgery and after bony fusion was assessed on lateral view of plain radiographs. Results: We had a total of 28 cases with tuberculosis of the subaxial spine managed by anterior debridement and stand alone grafting who satisfied the inclusion criteria. The mean age of the patients was 37.7 years and ranged from 14 years to 65 years. Neurological status was Frankel Grade C in 12, Grade B in 4, Grade D in 9, Grade E in 3. All the patients showed neurological improvement. Eleven patients with Frankel C improved to Frankel E and one to Frankel D. Two patients of Frankel grade B improved to Frankel E and the other two to Frankel D. All nine patients of Frankel D improved to Frankel E and all three patients of Frankel E remained in the same grade. The kyphosis angle at presentation ranged from 7° to 26° with a mean kyphosis of 15.8°. The average lordosis achieved immediately after surgery was found to be 3.14°, i.e., a correction of 19.2° (P value < .05). Conclusion: The functional outcome of patients treated by anterior debridement and stand alone bone grafting is good in terms of neurological outcome and bony fusion after surgery. There was significant correction of local sagittal profile and no major complication was noted. This method provides an acceptable alternative to anterior instrumented fusion in sub axial cervical spine tuberculosis.

422

P319: Site matters: Image Guided Percutaneous Sampling of Intervertebral Disc Results in Increased Positive Yield in Spondylodiscitis

Nektarios Mazarakis ¹ , James Baren ² , Peter Loughenbury ¹ , Christos Koutsarnakis ³ , and Richard Fawcett ²

¹ Leeds General Infirmary, Spinal Surgery, Division of Neurosciences, Leeds, United Kingdom

² Leeds General Infirmary, Interventional Radiology, Leeds, United Kingdom

³ Evaggelismos Hospital, Neurosurgery, Athens, Greece

Introduction: Spondylodiscitis is a common cause for referral to spinal on call services. Accurate microbiological identification of the causative organism is necessary to guide antibiotic treatment and to prevent the potential complications of spinal instability, deformity and neurological sequelae. A number of studies have examined the diagnostic yield of image guided biopsies but none have investigated whether sampling location affects the diagnostic yield. Materials and Methods: Retrospective review of 52 patients with suspected spondylodiscitis who underwent image guided percutaneous biopsy of either bone alone or bone & disc. All biopsies were carried out where there was no known organism and needle placement was identified using a computed tomography (CT) scan. Results: Overall positive diagnostic yield was 35%. When the bone and disc were used as the primarily sampling site the positive yield was the highest (47%). The positive yield dropped to 15% in samples that included only bone. Organisms identified included S. Aureus (7), M. tuberculosis (2), S. epidermidis (3), other coagulase negative staphylococci (2), group C and G streptococci (1), P. Acnes (1), Citrobacter Koseri (1) and one beta-haemolytic streptococcal infection. Conclusion: When sampling for suspected cases of spondylodiscitis the site of needle biopsy does matter and the inclusion of disc material seems to be a significant factor in obtaining a positive result.

457

P320: Independent Inter- and Intra-Observer Agreement Analysis of a New Classification of Pyogenic Spondylodiscitis

Gaston Camino Willhuber ¹ , Alfredo Guiroy ² , Juan Zamorano ³ , Nelson Astur ⁴ , and Marcelo Alejandro Valacco ⁵

¹ Hospital Italiano de Buenos Aires, Institute of Orthopedics “Carlos E. Ottolenghi,” Hospital Italiano de Buenos Aires, Buenos Aires, Argentina, Ciudad Autonoma de Buenos Aires, Argentina

² Hospital Español de Mendoza, Mendoza, Argentina

³ Clínica Alemana de Santiago-Universidad del Desarrollo, Santiago, Chile

⁴ Hospital Israelita Albert Einstein, San Pablo, Brazil

⁵ Hospital Churruca Visca, Ciudad Autónoma de Buenos Aires, Argentina

Introduction: Pyogenic spondylodiscitis can cause deformity, neurological compromise, disability, and death. Recently, a new classification of spondylodiscitis based on magnetic resonance imaging was published. The objective of this study is to perform an independent reliability analysis of this new classification. Material and Methods: We selected 35 cases from our database of different spine centers in Latin America and from the literature; 8 observers evaluated the classification and graded the scenarios according to the methodological grading of the classification developed by Pola et al. Cases were sent to the observers in a random sequence after 3 weeks to assess intraobserver reliability. The interobserver and intraobserver reliabilities were performed with Fleiss and Cohen statistics, respectively. Results: The overall Fleiss k value for interobserver agreement was substantial, with .67 (95% CI .43-.91) in the first reading and .67 (95% CI .45-.89) in second reading for the main types of classification. The Cohen k value for intraobserver agreement was also substantial, with .68 (95% CI .45-.92). The interobserver agreement analysis for the subtypes of this classification was overall substantial, with .60 (95% CI .37-.83) in the first reading and .61 (95% CI .41-.81) in the second reading. The overall intraobserver agreement for subtypes of the classification was also substantial, with .63 (95% CI .34-.93). Conclusion: The new classification developed by Pola et al showed substantial interobserver and intraobserver agreements. More studies are required to validate the usefulness of this classification especially in clinical practice.

470

P321: Boom of Pyogenic Spondylodiscitis With Varied Clinical Presentations: Experience From a Developing Country

Pramod Sudarshan ^{1 2} , Gowrishankar Swamy ² , and Pradeep Kumar ¹

¹ Aster MIMS, Calicut, India

² People Tree Hospitals, Bangalore, India

Introduction: Spine surgeons have a tendency to label all spondylodiscitis as tubercular due to the high prevalence in developing countries over the years. We revisit spondylodiscitis to notify the boom of pyogenic etiology with its varied presentations and stress upon the need for early diagnosis and treatment. Material and Methods: 42 patients with spondylodiscitis who were managed between 2015 and 2020 were reviewed. Treatment options constituted CT guided biopsy with medical treatment or surgical management in indications like failed conservative management, segmental instability, neurological deficits and severe pain. Clinico-radiological follow up was done at 1, 3 and 6 months. Results: 42 patients (M:30, F:12) with an average age of 48 yrs (15-73yrs). Neurological involvement was seen in 10 patients. Pyogenic surgical isolates were mainly Staphylococcus aureus. Surgery was necessary in 32 patients. Varied presentations like MSSA discitis with MODS, Proteus in cervical spine and Pseudomonas discitis with aortic aneurysm rupture were seen. 3D printed screw guides were used in one patient. ODI and Kirkaldy-Willis criteria showed excellent to good functional results at average follow-up of 36 months (6-60 months). One patient had posterior reversible encephalopathy syndrome, 2 cases required wound exploration and lavage. One mortality due to systemic sepsis. Conclusion: “All spondylodiscitis are tubercular unless it’s proved” can no longer be followed in developing countries. Early diagnosis and appropriate management is recommended to relieve patient of pain and prevent neurological complications as well as provide early rehabilitation.

497

P322: Hydatid Disease of the Spine

Thamer Hamdan ¹ , Bisola Ajayi ¹ , Mohsen Raza ¹ , Angelo Fragkakis ¹ , Jason Bernard ¹ , Timothy Bishop ¹ , and Darren Lui ¹

¹ St George's Hospital, Complex spine surgery, London, United Kingdom

Introduction: Hydatid disease in humans is caused mainly by the larval stage of the dog tapeworm Echinococcus granulosus. Although rare in Europe and the USA, the disease is endemic in Middle East, South America, Australia and India. Primary hydatidosis is common in the liver, spleen and lungs. 50% of skeletal involvement occur in the spine which are secondary. Theoretically it can occur at any site except the teeth, hair and nails. Due to its rarity, they are often missed as a differential diagnosis for paralysis. The aim of this study is to describe our experience in the diagnosis and management of spinal hydatid disease. Material and Methods: We analysed patients at a hospital in Iraq with spinal hydatid disease presenting with persistent back pain and progressive worsening in neurology that were non responsive to conservative management. Patients were diagnosed through clinical evaluation and the use of computed tomography (CT) and ultrasounds scans. All patients received albendazole 3 time daily for at least 1 year. Results: 20 patients were included in this study. All patients had surgical intervention to excise the pathological process as much as possible. 10 patients had transpedicular fixation. Decompression was achieved in some while total excision was not possible. 5 patients had complete recovery and 15 patients had a reoccurrence and residual disease. Conclusion: 15 patients had a reoccurrence of hydatid disease after surgical intervention. Hydatid disease of the spine is a malignant disease and should be made part of the differential diagnosis of patients who have travelled to endemic areas.

511

P323: Tuberculosis of the Cervical Spine: Operative Strategy and Clinical Outcomes

Ashwin Sathe ¹ , Tushar Rathod ¹ , Rajkumar Rathod ¹ , Nandan Marathe ¹ , Bhushan Hadole ¹ , Abhinav Jogani ¹ , and Shubhranshu Mohanty ¹

¹ Seth G.S. Medical college and K.E.M. Hospital, Orthopaedics, Mumbai, India

Introduction: Even after thousands of years of its existence, tuberculosis (TB) continues to remain a burden on the healthcare system, especially in developing countries. Spinal tuberculosis (TB) predominantly involves the thoracolumbar and thoracic spine. Cervical spinal TB (CSTB) is a relatively rare entity with incidence ranging from 3% to 5% of all the cases of spinal TB. The major concerns with CSTB include neurological impairment, direct compression by a large abscess on trachea/esophagus and development of kyphosis at the site of affection. Although TB is essentially considered a medical disease and modern-day antitubercular therapy (ATT) is the mainstay of the treatment, surgery is required for patients with extensive vertebral body involvement leading to severe kyphosis, instability, progressive neurological deficits, lack of improvement or deterioration while on ATT. This study was done to analyze the clinio-radiological outcomes in patients with cervical spinal tuberculosis (CSTB) who underwent surgical intervention. Material and Methods: A retrospective analysis of the clinical and radiological data collected from the records of 20 patients with TB of cervical spine, who underwent decompression, bone grafting and instrumented fusion during a period of 4 years (from June 2014 to August 2018) was done. Patients with a minimum 1-year follow up were included. Clinical & radiological parameters at the time of admission and at day1, 2-weeks, 6-weeks, 3-months and 6-months and 12-months postoperatively were obtained. The radiological parameters included the number of vertebrae involved, angle of segmental kyphosis, Maximal spinal cord compression (MSCC), and presence of signal changes in the cord. The functional outcome was assessed in the form of improvement in neurology, improvement in modified Japanese orthopedic association score (mJOA) and neck disability index (NDI). Results: The mean age was 37.5 ± 15.3 years. The average mJOA scores of the entire cohort of 20 patients improved from 9.00 to 16.1 (P-value <.001) at the end of 1 year follow up and the NDI changed from 90.90 to 23.20 (P-value <.001). The average pre-operative Cobb’s angle was 23.05 degrees which reduced to 3.0 degrees at day 1 post-surgery and at the end of 1 year follow up it was 4.0 degrees. There was a negative correlation between NDI and angle of kyphosis at the end of 1-year. (r: -.526) while mJOA and angle of kyphosis had a positive correlation with r = +.204. Conclusion: Significant improvement in neurology and function can be expected in the patients with CSTB undergoing anterior decompression of neurological structures along with supplemental stabilization using anterior or posterior instrumentation and ATT as per the drug sensitivity pattern. A clinically significant impact of residual kyphosis on the final functional outcome in CSTB could not be found in this study.

520

P324: Global Comparison of the Outcome of Surgical Techniques for Spondylodiscitis

Jessica Burton ¹ , Thamer Hamdan ¹ , Bisola Ajayi ¹ , Mohsen Raza ¹ , Angelo Fragakis ¹ , Cristina Lupu ¹ , Timothy Bishop ¹ , Jason Bernard ¹ , and Darren Lui ¹

¹ St George's Hospital, Complex Spine Surgery, London, United Kingdom

Introduction: Spondylodiscitis is an infection of the intervertebral disc and neighbouring bone. It is treated conservatively or surgically using a range of techniques. The aim of this review is to determine whether the surgical techniques between different countries have an effect on clinical outcome: postoperative complications, relapse rate, treatment failure rate or mortality rate. Material and Methods: Many articles were screened using Ovid and Pubmed databases for studies pertaining to the surgical treatment of spondylodiscitis. Paediatric studies, tubercular/brucellar/fungal/ postoperative infection and case reports were excluded from this review. Results: The results shows that no differences in the outcome of surgery between countries was found, and reasons for this along with solutions for moving forward with comparing surgical techniques worldwide are noted. Conclusion: In conclusion, there is little to no difference in surgical outcome when treating spondylodiscitis across different countries. No surgical technique stood out as more effective so it may be beneficial to study more in depth the other clinical outcome in different countries to further analyse their surgical techniques.

559

P325: Is it Worthwhile to use Drains in Spine Surgery?

Sathish Muthu ^{1, 2} , Girinivasan Chellamuthu ^{1, 3} , and Eswar Ramakrishnan ⁴

¹ Orthopaedic Research Group, Coimbatore, India

² Government Hospital, Velayuthampalayam, Karur, India

³ Ganga Hospitals, Orthopaedic Trauma, Coimbatore, India

⁴ Rajiv Gandhi Government General Hospital, Institute of Orthopaedics & Traumatology, Chennai, India

Introduction: With the widespread awareness of morbidity and health care expenditure caused by Surgical Site Infection (SSI) in spine surgeries, a multi-faceted approach involving various peri-operative pharmacological and surgical measures were being ascertained to prevent its occurrence. The use of surgical drain remains as one such surgical measure. The practice was mainly started in spine surgery to prevent the formation of epidural haematoma which could cause neurological deficit by its mass effect on the cord and increasing the tension on the incisions resulting in wound-related complications. Wound drain being a double-edged sword, apart from aiding in SSI prevention, wound drains could cause retrograde infection, increase post-operative blood loss which increases the need for blood transfusion. Hence, we aim to analyse the literature evidence available to support the usage of wound drain in various scenarios of spine surgery and provide an evidence summary on the surgical practice. Materials and Methods: We conducted independent and duplicate electronic database searches adhering to PRISMA guidelines in PubMed, Embase, and Cochrane Library till April 2020. Quality appraisal was done as per Cochrane ROB tool and evidence synthesis was done as per GRADE approach. 5 domains of spine surgery with associated key questions were identified. Evidence tables were generated for each question and critical appraisal done as per the GRADE approach. Results: 23 studies (9-RCTs,4-Prospective studies,10-Retrospective studies) were included. Analysis of studies in cervical spine either by anterior or posterior approach and single/multilevel thoracolumbar spinal surgeries did not show any evidence of reduction in surgical site infection (SSI) or haematoma formation with the use of drain. Deformity correction surgeries and surgeries done for trauma or tumour involving spine also did not find any added benefit from the use of wound drains despite increasing the total blood loss. Conclusion: Evidence from this review suggests that routine use of drain in various domains of spine surgery does not reduce the risk of SSI and their absence did not increase the risk of haematoma formation. The current best evidence is presented with its limitations. High-quality studies to address their use in spine surgeries in cervical, trauma, and tumour domains are required to further strengthen the evidence synthesised from available literature.

572

P326: Pyogenic Vertebral Osteomyelitis in Tyumen Regional Hospital No.2 from 2006 to 2017 Years

Alexander Bazarov ¹ , Konstantin Sergeev ^{2, 3} , Aleksei Farion ³ , and Roman Paskov ^{2, 4}

¹ Tyumen regional hospital No2, Traumatology and Orthopedic Department No3, Tyumen, Russian Federation

² Tyumen State Medical University, Traumatology and Orthopedics with a course in Pediatric Traumatology, Tyumen, Russian Federation

³ Tyumen Regional Hospital No2, Traumatology and Orthopedic Department No1, Tyumen, Russian Federation

⁴ Tyumen Regional Hospital No2, Tyumen, Russian Federation

Introduction: pyogenic vertebral osteomyelitis (PVO) is the disease which is both life-threatening and hard to diagnose; it is also characterized by late diagnosis. PVO that was diagnosed at an early stage and had no complications responds well to non-surgical treatment. Late diagnosis can lead to the vertebral destruction, unstability, abscess formation; in such cases, the surgical treatment has to be applied. Case complications and risk factors increase the number of unsatisfactory results, treatment failure and mortality rates. Material and Methods: a retrospective analysis of 209 PVO cases was conducted in the Tyumen Regional hospital #2 in 2006-2011 (Russia). Non-surgical treatment was given to 68 (32.5%); surgical - to 141 patients (67.5%). 93 pathogen strains were isolated from the focus of infection of 77 patients, 20 strains – by aspiration biopsy of 32 patients (62.5%), 21 strains – by blood cultures of 20 patients. Drainage, instrumentation and anterior fusion with posterior stabilization were applied. Statistics of the research was analyzed. Results: PVO pathogen was isolated in 117 patients (56,0%). Gram-positive pathogen was isolated in 56.3% cases. Staphylococcus spp was the main pathogen (53.8%): 35.5% of those were MSSA and 3.3% - MRSA. In 30.5% cases anaerobic pathogen was identified (n = 37). In 26 cases (12.4%) two or more pathogens were isolated. In all the PVO cases, the initial antibacterial therapy included: cefazolin (20%), oxacillin (30%), protected aminopenicillin (50%) ± gentamicin. Vertebral instrumentation was performed for 81 patients (57,4%), drainage - for 32 (22,7%), anterior fusion with instrumentation – for 28 (19,9%). Minimal invasive spinal surgery was used in 47 cases (33.3%). The treatment failed in 20 cases (9.6%). The relapse after the surgical treatment was noted in 12.0% (n = 17), after non-surgical treatment – in 4.4%. The main reasons of the relapse were: diabetes decompensation, ongoing drug-addiction. The failure risk in PVO cases caused by MSSA is reliably higher (P = .015), for MRSA - P = .004. The relapse risk is statistically higher among drug-addicts in the group who had surgery (P= .039). 17 patients had the surgery repeated, 9 of those with good outcome within 1.5-13 years. Mortality rate (n = 9) makes up 4.3% that is higher for the patients with diabetes among the general number of patients (P = .012), among after-surgery patients (P = .006). The majority of the patients had positive recovery as the result of the treatment (86.1%). Conclusion: gram-positive pathogen, with MSSA dominating, is found to be the most frequent cause of PVO. Anaerobic pathogens were identified in 30.6%. In 26 cases (12.4%) more than one pathogen was isolated. PVO relapse happened in 9.6%, post-surgery - 12.0% (n = 17), failure after non-surgical treatment – in 4.4%. Relapse risk increases in diseases caused by MSSA (P = .0015), as well as by MRSA (P = .004). Relapse risk is significantly higher among drug-addicted patients (P = ,039) in post-surgery group. Hospital mortality (n = 9) is 4.3%. Mortality cases are noted among patients with diabetes (P = .012) and in the group of patients with surgery (P = .006). The provided treatment brought 86.1% of positive outcomes (n = 180); including treatment after the relapse – 90.4% of positive results (189 cases).

581

P327: Pyogenic Osteomyelitis of Cervical Spine. characteristic of Complicated form of Disease

Alexander Bazarov ¹ , Konstantin Sergeev ^{2 3} , Aleksei Farion ³ , and Roman Paskov ^{2 4}

¹ Tyumen regional hospital No2, Traumatology and Orthopedic Department No3, Tyumen, Russian Federation

² Tyumen State Medical University, Department of Traumatology and Orthopedics with a course in Pediatric Traumatology, Tyumen, Russian Federation

³ Tyumen regional hospital No2, Traumatology and Orthopedic Department No1, Tyumen, Russian Federation

⁴ Tyumen regional hospital No2, Tyumen, Russian Federation

Introduction: Pyogenic osteomyelitis of cervical spine (PVO) is defined as a rear disease and it is characterized by a variety of clinical symptoms, most common of which are acute neck ache and fever. The average rate of PVO incidents is 2-2.4 cases per 100,000 people per year. The affected areas tend to be of the same distribution: lumbar affected 50-73.6%, thoracic – 30-40%, cervical – 3-10%. In cases when PVO affects cervical spine, it is frequently accompanied by spinal epidural abscess (SEA) in 57.9%, and neurological deficit 68.4%. Material and Methods: According to the records of the Regional Hospital #2 in Tyumen, Russia, 209 PVO patients were treated in the period 2006-2017, among which patients with cervical spine affected – 20 cases (9.6%). Neurological deficit was noted in 37 cases (17.7%) among all the patients, and in 15 cases (75%) among patients with affected cervical spine. The patients’ average age is 49.1 ± 15.01. The sex ratio is F:M = 1:4 in cases of cervical PVO. SEA has been diagnosed in 9 cases (60%) in cervical PVO, or in 24 cases (11.5%) of all patients with PVO. In other cases, neurological deficiencies were caused by vertebral spinal cord compression or instability 40% (n = 6). Results: Staphylococcus aureus was identified in 58.3%. The severity of the neurological deficit, according to the Frankel scale, on the patients’ arrival day: A – 2, B – 2, C – 7, D – 3, E – 1; on their release day: A – 2, B – 0, C – 4, D – 6, E – 3. When comparing groups of patients with neurological deficit according to different affected spinal areas, it has been noted that the risk of developing neurological deficit is reliably higher (P = .001) if cervical spine is affected, rather than other spinal areas. 14 patients (93.3%) received surgical treatment. Other treatments were applied: drainage and debridement – 66.7% (n = 10), anterior fusion and stabilisation 26.7% (n = 4). Application of anterior fusion and stabilisation did not lead to the decrease of neurological deficit. The main reason for fusion and stabilisation procedure is to allow the patient the opportunity of early mobility, easy care and access to rehabilitation activities. 6 patients (40%) were released without any positive dynamics; 4 patients (26.7%) – with improvement by one Frankel classification grade; 2 patients (13.3%) – with improvement by two grades; 1 patient (6.7%) – with improvement by three grades. The negative dynamics – deterioration from grade B to A – was noted with 2 patients (13.3%). It was possible to decrease the neurological deficit in 46.7% of cases. Non-surgical treatment was given to one patient with the mild form of PVO. Hospital mortality in cases with cervical PVO is 13.3% (n = 2). Conclusion: affection of cervical spine is accompanied by maximum risk of neurological deficit, which is reliably higher than in cases of thoracic and lumbar PVO (P = .001). The main treatment is surgical. The applied treatment allowed partial or full regression of neurological deficiencies in 46.7% of cases. Addition of drainage and debridement stabilisation offers the patients early rehabilitation process, eases their care, but did not decrease instances of neurological deficit.

610

P328: Spinal Column Hydatid Cyst Disease: An Institutional Experience

Kais Maamri ¹ , Ines Cherif ¹ , Mohamed Boukhit ¹ , Mahmoud Ben Messaoud ¹ , Mohamed Amine Hadj Taieb ¹ , Maher Hadhri ¹ , Mohamed Badri ² , and Mehdi Darmoul ¹

¹ Fattouma Bourguiba University Hospital, Neurosurgery, Monastir, Tunisia

² Trauma and Major Burns Center Ben Arous, Neurosurgery, Ben Arous, Tunisia

Introduction: Hydatid cyst is a disease caused by the larvae of the Ecchinococcus granulosus cestode and is commonly seen in the Mediterranean region, Middle East and India. 60 to 70% of hydatid cysts are formed in the liver, while 10 to 15% involve the lungs. Bone involvement is rare and observed only in .5 to 2% of all hydatid cyst cases, with approximately half of them residing in the vertebrae. We report the treatment’s challenges of spinal column hydatid cyst in 8 cases treated over a period of 30 years. Materials and methods: We report a retrospective study of 8 cases of spinal column hydatid cysts treated in the neurosurgery department of Monastir Tunisia, between January 1985 and December 2014. Results: It’s about 4 males and 4 females aged from 20 to 68 with a mean age of 42. The revealing clinical symptomatology was spinal cord compression in 5 cases, back pain in 2 cases and sciatica in 1 case. The radiological assessment revealed dorsal hydatidosis in 4 cases, dorsolumbar junction in 2 cases and lumbosacral in 2 cases. All the patients were operated and treated with antihelminthic (zentel). The evolution was marked by relapse in 7 cases of which 6 were reoperated. The average follow-up of patients after treatment was 3.5 years. Conclusion: Spinal hydatid cyst is a serious disease with significant morbidity. These lesions are difficult to treat due to the frequency of relapses. The recommended treatment is surgery with anterior or posterior approach and spinal cord decompression via instrumentation in suitable cases, and subsequent adjuvant medical therapy. The results are rarely satisfactory and the prognosis is usually poor.

Keywords

Echinococcosis, Hydatid cyst, surgical treatment, Spinal hydatid cyst

613

P329: Intramedullary Tuberculoma: A Case Report

Khalil Ayadi ¹ , Fatma Kolsi ¹ , Anis Hachicha ¹ , Mansour Khrifech ¹ , Firas Jarraya ¹ , and Boudawara Mohamed Zaher ¹

¹ Habib Bourguiba University hospital, Neurosurgery, Sfax, Tunisia

Introduction: Intramedullary tuberculoma is a rare condition. It affects mainly patients in developing countries. Diagnosis and treatment can be challenging. Material and Methods: We report the case of a young patient who was diagnosed with intramedullary tuberculoma and was treated in the department of neurosurgery in the Habib Bourguiba hospital in Sfax, Tunisia. Results: The patient was a 21-year-old female. She had a history of pulmonary tuberculosis. She was admitted for walking disturbances with sphincter dysfunction. Physical examination found a spastic paraparesis with a T8 sensitive level. The patient had anal sphincter hypotonia, vesical retention and bilateral Babinski sign. Spinal MRI showed an intramedullary nodular mass at the level of T7. The patient underwent urgent surgery. Tumor removal was not complete due to adherences. Pathology was in favor of tuberculoma. The patient had physical therapy along long-term antibiotics. She was symptom-free few weeks after surgery. Conclusion: Intramedullary tuberculoma is rare. However, such diagnosis should be considered in some contexts. Surgery when possible followed by medical treatment is the best alternative.

632

P330: Sacral Hydatidosis

Khalil Ayadi ¹ , Fatma Kolsi ¹ , Mansour Khrifech ¹ , Anis Hachicha ¹ , Firas Jarraya ¹ , and Boudawara Mohamed Zaher ¹

¹ Habib Bourguiba University hospital, Neurosurgery, sfax, Tunisia

Introduction: Hydatidosis is a parasitosis caused by the larva of the taenia Ecchinococcus Ganulosis. The bony localization of hydatidosis remains rare and is characterized by its clinical latency which delays diagnosis and favors the extension of the affection. Material and Methods: We report the case of a patient who was treated for a sacral hydatid cyst in the department of neurosurgery in the Habib Bourguiba hospital, in Sfax, Tunisia. Results: The patient is a 44-year-old man with no medical history. He was living in a rural area and was a shepherd. The patient was admitted for progressive back pain. He noted that he had sexual impotency for few weeks and no sphincter dysfunction. Clinical examination objected an isolated distal paraparesis. Lumbar MRI revealed multilocular cystic lesions in the sacrum with osteolysis. The patient underwent surgery. The removal of the cysts was challenging and could not be complete. The patient developed a distal motor deficit after surgery. Pathology was in favor of hydatidosis. Albendazol was admitted to the patient. With physical therapy the patient had partial motricity however sexual impotency did not improve. Conclusion: Vertebral hydatidosis is a rare entity. It is characterized with its latency. Symptoms are not specific and spinal MRI is the key to diagnosis. Treatment depends on maximal cyst removal and on medical treatment. Prognosis is generally poor. Prevention is the best means of protection.

633

P331: Disc Dysbiosis as a Cause Of Inflammaging and Lumbar Intervertebral Disc Degeneration- Revelations From Next Generation Sequencing Analysis

Shanmuganathan Rajasekaran ¹ , Dilip Chand Raja Soundararajan ¹ , Chitraa Tangavel ² , Monica Steffi Matchado ² , Sharon Miracle Nayagam ² , and Sri Vijay Anand KS ¹

¹ Ganga Medical Centre and Hospitals Pvt Ltd, Spine Surgery, Coimbatore, India

² Ganga Research Centre, Biotechnology, Coimbatore, India

Introduction: Apart from mechanical and genetic etiology, the possibility of sub clinical infection and inflammaging as a cause of disc disease and back pain is a raging controversy. The organisms implicated are fastidious and require stringent clinical atmosphere and have low positivity in traditional methods of culture and identification. The use of Next Generation Sequencing has revolutionized our ability to identify the presence of organisms even in low quantity and has thus questioned the traditional concept, that a healthy lumbar disc is sterile. The aim of the study was to analyze the microbiome of lumbar discs in health and disease. Materials and Methods: Eight Degenerated (DD) and eight control disc tissues (ND) were obtained from MRI normal spine segments harvested from voluntary organ donors. Sequence analysis of bacterial 16S rRNA genes containing the hypervariable V1-V9 regions were performed to study the composition of the human disc microbiome in heath and disease using the Illumina MiSeq platform. Results: All 16 samples had bacterial presence with varying diversity and abundance. Proteobacteria was the most abundant phylum of bacteria in both DD and ND. However, the Normal discs were characterized by a higher abundance of Firmicutes and Actinobacteria (protective gut commensals). At genus level, ND harbored 21 different abundant genera compared to only 13 in DD. Pseudomonas was abundant in DD (50%) and only 14.55% in ND. The second most abundant genus in ND, Sphingomonas (12.28%) was decreased in DD (4.68%). Beneficial bacteria like Proteobacteria (Herbaspirillum and Devosia), Firmicutes (Lentibacillus, Planomicrobium and Virgibacillus) and Actinobacteria (Saccharopolyspora) were present only in ND. A total of 355 species were identified in ND compared to only 346 in DD. Blautia producta (gut-microbe), Propionibacterium granulosum (skin-commensal) and Sphingomonas yabuuchiae (anti-tumoral) were found to be abundant in ND when compared to DD. In ND, 32 unique bacteria including known probiotics (Bacillus coagulans and Bacillus clausii) and bacteria with antimicrobial properties against Pseudomonas aeruginosa and Staphylococcus aureus (Bdellovibrio bacteriovorus) were present. Interestingly, pathogenic bacteria (Prevotella tannerae, Halomonas nitritophilus, Streptococcus alactolyticus, Streptococcus anginosus, Prevotella pallens, Avibacterium gallinarum and Enterobacter cowanii) were present only in DD. Conclusion: The relative abundance of bacteria varied significantly between ND against DD. Although Pseudomonas species were common to both groups, relative abundance was very low in ND. Further the presence of 32 unique bacteria in ND indicate differing ratios of protective and pathogenic bacteria in both groups implying ‘Dysbiosis’, a phenomena implicated in various diseases which is defined as any perturbation of the normal microbiome content that could disrupt the symbiotic relationship between the host and associated microbes resulting in disease. Our documentation of diverse pathogenic bacteria strongly supports ‘inflammaging’ theory.

658

P332: Lytic Olisthesis as a Site of Locus Minoris Resistentiae for Hematogenous Spinal Infection

Hamdan Abdelrahman ^{1, 2} , Mootaz Shousha ³ , and Heinrich Boehm ⁴

¹ Helios Hospitals Erfurt, Erfurt, Germany

² Asiut Universty Hospitals, Asiut, Germany

³ Zentralklinik Badberka, Bad Berka, Germany

⁴ Zentralklinik Badberka, Bad Berka, Germany

Introduction: Parallel to increased risk and predisposing factors the incidence of vertebral osteomyelitis is rising. There are many systemic factors which can negatively affect the immune system. The term locus minoris resistentiae is defined as a place of reduced resistance (any part or organ which is more susceptible than others) against the attack of a morbific agent. Spinal instability has rarely been described as a cause of depressed localized immunity. In this study, we present 18 patients with hematogenous infection on top of preexisting lytic olisthesis (LO) in the lumbar spine. Methods: A retrospective clinical case-series. Out of 402 patients who have been treated in our center for haematogenous lumbar spinal infection. Between Jan. 2005 and Dec. 2015 we have identified 23 patients with LO. Of those 18 (78%) attracted the infection at same site of the LO (15 with grade I, 2 with II and one grade III olisthesis). We analyzed the preoperative condition, risk factors, diagnostic findings and presentation, causative organisms, treatment and outcomes. Results: In the total of 18 patients males dominated females by 14 to 4 with a mean age of 67.7 years (49-85). Of them 14 patients were overweight or obese (mean BMI of 27.7), 8 patients had ASA score of III or more, 6 suffered from DM, another 6 from cardiac diseases and two from liver cirrhosis. Other sites of infection were found in 7 patients. Neurological deficit (ASIA C&D) at the time of presentation had developed in 6 cases, fever in another 6. Multifocal infection was found in 2 cases, additional epidural abscess in 11 and psoas abscess in 6 individuals. All patients except 1 patient, diagnosed with CT-guided biopsy and treated conservatively required surgery (ventrodorsal technique in 11 patients and PLIF technique in 6 cases). The mean follow up (FU) reached 3.5 years. Mean CRP at time of presentation was 66 mg/l (8.9 at last FU), WBC of 9.6x10³/mm³ (6.7 at last FU) and ESR of 76 mm/h (31 at last FU). A causative organism could be isolated in12 patients (67%); Staph. epidermidis in 4 of them. Neurological deterioration occurred in one patient, one morbidly obese individual had postoperative wound healing problems and one patient had to be reoperated 11 months later due to infection of the adjacent cranial segment. Discussion: Spinal osteomyelitis is commonly caused by hematogenous seeding. Predisposing factors that compromise the immune system render the host more susceptible to spinal infection. The LO represents a suitable site for inoculation of organisms and in this series increased the possibility of development of infection up to 78%. The altered vascularity leads to blood stagnation and facilitates the bacterial seeding. The LO could be an example of locus minoris resistentiae that can attract an organism and develop spinal infection.

686

P333: Multiple Level Butterfly Vertebrae (Mosiac Spine) Presented With Spondylodiscitis: Case Report and Review of the Literature

Hamdan Abdelrahman ¹ and Mohamed El-Meshwawy ¹

¹ Asiut Universty Hospitals, Asiut, Egypt

Introduction: Butterfly vertebra, as symmetric fusion defects resulting in sagittal cleft vertebra, is a rare congenital malformation of the spine. More than 100 years ago Rokitansky reported about a 55-year-old man with a butterfly vertebra in the 12th thoracic vertebra. Only 15 cases are published but cases with multiple level butterfly vertebrae were very rarely described before. We report a case of butterfly vertebrae involving almost the whole thoracic and lumbar spine who presented with spondylodiscitis. Methods: A 50-years-old man, on renal dialysis, presented with history of severe low back pain of 20 days. The patient was evaluated clinically, radiologically and with laboratory investigations. The diagnosis was confirmed with multislice computerized tomography (CT) and magnetic resonance imaging (MRI) scans. Results: The clinical examination showed rigid back and severe tenderness at the lower lumbar level. Routine examination of the motor and sensory status was found to be normal. Plain x-rays of the thoracic and lumbosacral spine showed features suggesting butterfly vertebrae in the thoracolumbar spine. The laboratory investigations revealed total leukocyte count of 10,000/mm3, erythrocyte sedimentation rate (ESR) of 60 mm/hr., C-reactive protein (CRP) of 148 mg/dl and pathological renal function tests. MRI and CT scans of the spine showed ultrashort spine, lumbosacral scoliosis, butterfly vertebrae from Th3 till L5 (atypical mosaic spine) and evidence of lower lumbar spine infection. In addition a unilateral renal agenesis was seen. The patient was referred to the nephrologist to assess and prepare him for operative intervention, but from the medical condition the patient was not capable for surgery, so the conservative treatment was advisable. After a total of 12 weeks of antibiotics the patient improved clinically and retained to his daily activities. Conclusion: Multiple Butterfly vertebrae are a very rare anomaly. The finding of butterfly vertebrae was coincidental in many patients when they were evaluated for back ailments. It can be associated with disabling disorders (Alagille syndrome, Jarcho-Levin syndrome). In case of a single butterfly vertebra, the condition may be easily confused with a traumatic compression fracture or a pathologic fracture. Knowledge of this benign spinal anomaly, which may be confused with many pathologic conditions, helps in making rational use of extensive noninvasive and invasive diagnostic procedures.

705

P334: Spondylodiscitis Investigation and Therapeutic Protocol: Neurosurgery Service Results

Guilherme Finger ¹ , Andre Martins de Lima Cecchini ¹ , Ericson Sfreddo ¹ , Felipe Martins de Lima Cecchini ¹ , Tobias Ludwig do Nascimento ¹ , and Asdrubal Falavigna ²

¹ Cristo Redentor Hospital, Neurosurgery Spine, Porto Alegre, Brazil

² Caxias do Sul University, Neurosurgery Spine, Caxias do Sul, Brazil

Introduction: Spondylodiscitis is still a frequent pathology among neurosurgical services, and its correct treatment involves infectious, neurological and orthopedic goals. The authors describe the protocol and report the diagnostic and therapeutic results after its imple- mentation. Methods: A prospective prognostic study (Level I) including patients with primary spondylodiscitis treated in the Neurosurgical Service of Cristo Redentor Hospital from January 2014 to March 2018. Demographic, spine, infectious and treatment-related variables were analyzed. The numerical variables are presented as mean and standard deviation or median and interquartile range (according to their parametricity), and are compared by the student’s t-Test or Mann-Whitney U Test, respectively. Results: Thirty seven patients were included. The sexes were evenly distributed, with predominantly Caucasians, and a mean age of 56.89 ± 15.33. Hypertension and type 2 diabetes were the most frequent comorbidities. Vertebral lumbar level was the most involved segment. Pathogens were identified in 34 cases (91%), with Staphylococcus aureus being the most prevalent, followed by Koch Bacilli. Inflammatory markers are higher in pyogenic infections at hospital admission, but lower at hospital discharge when compared to tuberculous discitis (P < .01). Mean hospital stay was higher in the pyogenic group. Conclusion: The protocol described has a high diagnostic level of the pathogen, with cure of infection and satisfactory neurologic outcome in all cases.

752

P335: Pyogenic Spondylodiscitis: What is the Proper Treatment? 

Slavisa Zagorac ^{1, 2} , Jovana Grupkovic ¹ , Milos Vasic ¹ , Uros Novakovic ¹ , and Goran Tulic ^{1, 2}

¹ Clinic for Orthopedic Surgery and Traumatology Clinical Center of Serbia, Belgrade, Serbia

² Medical faculty University of Belgrade, Belgrade, Serbia

Introduction: Pyogenic spondylodiscitis or vertebral osteomyelitis is a rare infection that has a high morbidity and mortality rates. It is most commonly caused by Staphylococcus aureus, and less frequently by S.epidermidis, gram negative bacteria, Pseudomonas and Salomonella. The incidence is .4-2.0 in 100.000 persons according to the latest data. It affects adults between the age of 50 to 60. The most common location is lumbar spine. In recent years the number of patients is growing due to the increased number of elderly and immunocompromised. In terms of onset it is divided in 3 categories : acute, subacute and insidious, depending on the severity and intensity of the symptoms. Most sensitive diagnostic tool, as well as the diagnostic gold standard, remains the MRI. Alternatives include Technetium Tc99m bone scan for patients who can’t have an MRI, although it lacks specificity. X rays should be taken for every patient with possible pyogenic spondylodiscitis, but it takes at least 2-8 weeks from the onset of first symptoms for them to detect the changes (soft tissue swelling, disc destruction, etc). Differential diagnosis include spine tumors, as well as vertebral osteomyelitis with different ethiology (viral, fungal). There are two possible approaches to treatment: conservative and surgical. Conservative treatment implies the use of antibiotics (according to results of microbiologic analysis, as well as biopsy results) and spine immobilization (6-12 weeks). Surgical approach varies depending on the location and severity of the infection. Purpose: The aim of our study was to review the literature published in the last 10 years regarding pyogenic spondylodiscitis and methods of treatment, in order to integrate experiences and latest conclusions of fellow spine surgeons, as well as highlight the need for treatment guidelines. Material and Methods: We conducted a systematic electronic search of PubMed, MEDLINE, EMBASE and Cochrane collaboration concerning the treatment of pyogenic spondylodiscitis. We used keywords ‘’pyogenic spondylodiscits’’, ‘’pyogenic spondylitis’’ and ‘’spinal pyogenic infection’’. Inclusion criteria included review articles, that were published in the last 10 years in relevant scientific orthopeadic and neurosurgical journals. Case reports were excluded. GRADE approach was used to determine the quality of evidence and strength of recommendation. Results: Twenty studies were included. Currently most authors agree that treatment strategy for pyogenic spondylodiscitis has to be determined case by case. Minimally invasive surgery is the surgical option of choice where possible, as it has the most favorable outcome. CT guided biopsy is the most important tool, to be able to guide the antibiotic therapy. Conclusion: The majority of authors agree that there is a great need for more randomized and bigger clinical researches so we can be able to establish guidelines for the treatment of this rare, but life threatening condition with debilitating sequeale including severe pain, spine instability and neurologic deficits.

753

P336: The use of Negative-Pressure Wound Therapy as an Strategy to Reduce Site Infection for Spinal Deformity Surgery on Pediatric Population

Fernando Alvarado Gómez ¹ , María Alejandra Asmar ² , and Juan Sebastian Rojas ¹

¹ Instituto Roosevelt, Bogota, Colombia

² Universidad de los Andes, Bogota, Colombia

Introduction: Infection after a pediatric spinal deformity surgery is a common complication reported with a range that oscillates between .4% and 8.7%. That is why surgeons have not only improved their surgical techniques but they have create strategies to prevent complications during and after surgery. The risk mitigation is one of this strategies, it consists in a multidisciplinary assessment determining the general state of the patient by the clinical history and laboratories. The negative-pressure wound therapy (NPWT) is another method used to reduce surgical site infections but its real effect on spine surgery and especially in Colombian population is not well known, giving importance to this study. Materials and methods: At Roosevelt Institute, Colombia, every year more than 150 procedures are performed for scoliosis surgery and spine growing rod system. During the years 2017 and 2018 infection mean was 4.5% and great part of them had neuromuscular scoliosis. Six cases of pediatrics patients undergoing to spinal deformity surgery were selected and all the information of them were collected prospectively. Results: The mean age was 13 years old and the majority of them were female. Two patients had congenital scoliosis and another two had idiopathic scoliosis, one had neuromuscular scoliosis and the last one had syndromic scoliosis. The range of the cobb angle was between 143° and 98°. Every patient needed more than one surgical stage, five of them undergo to two surgical stages and one patient used an extra surgical stage. All patients used the NPWT device and none of them presented any infection or wound defect. Conclusión: We recommend the use of NPWT in highly complex patients undergoing to spinal deformity surgery who would require more than one stage because it thus hasten the healing process what prevents dehiscence and infections of the surgical site. In addition, the hospital stay were one day less than those who did not use the device what implies cost reduction for the hospital.

837

P337: Correlation of Postoperative Infection With the Etiology of the Disease in Spinal Surgery With Instrumentation

Leandro Kim ¹ , Nelson Astur ¹ , Rodrigo Góes Medéa de Mendonça ¹ , Alberto Gotfryd ¹ , and Robert Meves ¹

¹ Santa Casa de São Paulo, Orthopedics and Traumatology Department, SAO PAULO, Brazil

Introduction: Surgical site infection is among the most frequent complications of the spine surgery. The objectives of this study were to evaluate the epidemiological characteristics of postoperative infection in surgeries of the spine with instrumentation in our service, and whether there is a correlation between the rate of postoperative infection and the etiology of the indication for the primary surgical procedure. Material and Methods: A retrospective search through medical records of patients who underwent spinal surgery with instrumentation in our hospital between 2015 and 2019 was performed, and the ones that evolved with acute or chronic postoperative infection with need for surgical cleaning to resolve it were selected. Cases of non-instrumented surgery, primary infection of the spine (osteomyelitis and spondylodiscitis) and superficial infection of the surgical wound without the need for surgical cleaning were excluded. Results: The rate of postoperative infection was 11.6%. In this group of patients who evolved with this complication, most were submitted to surgery primarily for trauma (38.9%), followed by degenerative disease (30.8%), neoplasm (19.2%), and deformity (15, 4%). However, when we analyzed these patients comparing them with the total number of cases of spinal surgery with instrumentation performed in the period, we obtained a higher prevalence of infection in patients operated for deformity (17.6%), followed by degenerative disease (13%), neoplasm (11.4%) and trauma (9.9%). This difference did not prove to be statistically significant (P = .79), nor the correlation with sex and age. Conclusion: In our study, proportionally, there was a difference in the prevalence of postoperative infection according to the etiological indication, being higher in cases operated for deformity, mainly due to neuromuscular disease.

855

P338: Anterior Cervical Debridement and Fusion for Cervical Pyogenic Spondylodiscitis: Use of Anterior Cervical Plating or Not?

Sungkyu Kim ¹ , Jongbeom Park ² , Dongho Lee ³ , Youngyul Kim ⁴ , and Sohyun Moon ⁵

¹ Chonnam national university medical school and hospital, Department of orthopaedics, Gwangju, South Korea

² College of Medicine, The Catholic University of Korea, Department of orthopaedics, Seoul, South Korea

³ Asan Medical Center, University of Ulsan College of Medicine, Department of orthopaedics, Seoul, South Korea

⁴ College of Medicine, The Catholic University of Korea, Department of orthopaedics, Daejeon, South Korea

⁵ Chosun University, Department of Nursing, Gwangju, South Korea

Introduction: Due to concerns about bacterial seeding on the foreign material after instrumentations in pyogenic infections, the safety and efficacy of anterior cervical plating for cervical pyogenic spondylodiscitis (CPS) are still undetermined and controversial. Little information is available about the safety and efficacy of anterior cervical plating to manage CPS. We sought to evaluate the safety and efficacy of anterior cervical plating in anterior cervical debridement and fusion (ACDF) for patients with CPS. Material and Methods: Twenty-three patients who underwent ACDF with (n = 12) or without (n = 11) plating for CPS were included. The mean age was 62.6 years. Medical records were reviewed and radiological parameters including segmental height, segmental angle, C2–C7 angle, and fusion status were analyzed. The mean follow-up period after surgery was 21.3 months. Results: After ACDF with plating, segmental height, segmental angle, and C2–C7 angle were significantly improved compared with preoperative conditions and remained well-maintained at the last follow-up. After ACDF without plating, three radiological parameters were also initially improved compared with preoperative condition, but significantly deteriorated to preoperative levels at the time of the last follow-up. The fusion rate was higher in the ACDF with plating group compared with the ACDF without plating group (90.9% vs 63.6%; P < .01). One patient who received ACDF with plating and four patients who received ACDF without plating underwent revision surgery due to nonunion or bone graft dislodgement. No recurrence of pyogenic spondylodiscitis occurred in either group. Conclusion: ACDF with plating showed better surgical outcomes compared with ACDF without plating for CPS. We recommend the use of anterior cervical plating, which can provide biomechanical stability, for better healing of CPS. To our knowledge, this is the largest surgical case series of CPS.

934

P339: Comparative Analysis of Decompression Versus Decompression With Instrumentation Surgery in Tubercular Paraplegia

Arul Kumar ¹ , Ajit Singh ¹ , Raj Kumar Arya ² , and Gautam Tripathi ²

¹ Institute of Medical Sciences, Banaras Hindu University, Orthopaedics, Varanasi, India

² Institute of Medical Sciences, Banaras Hindu University, Varanasi, India

Backround: Tuberculosis is quite common disease in developing countries Spine is a common site for extra pulmonary tuberculosis. The treatment perspectives for tuberculosis of spine have gradually evolved from "reducing the mortality" to "reducing the morbidity" to "reducing the deformity". The treatment for spinal TB remains a difficult and challenging decision making process, given the lack of evidence and guidelines on the optimal treatment and management strategies. The objective of this study is to evaluate the efficacy and clinical outcomes of different treatment approaches of spinal TB, including decompression surgery, autogenous bone grafting with or without instrumentation and anti-TB chemotherapy. Methods: It is a type of Retrospective study design comprised of 37 patients operated with anterior debridement, spinal cord decompression with bone grafting and with or without instrumentation, having a minimum follow up of 1 year. It includes patients of tubercular spondylitis of age group 14 and above, classified according to Tuli’s classification and early onset cases involving cervical, dorsal and dorso-lumbar tubercular spondylitis with paraplegia were also included. And to compare the outcome in the form of neurology and kyphosis correction and progression in cases with anterior decompression with bone grafting (Group I) and in cases of anterior decompression with bone grafting and instrumentation (Group II). Result: Post operatively kyphotic correction progression was significantly less in instrumented group in anterior approach as compared to non instrumented group. The final neurology at 1 year follow up was same in both groups. The use of anterior instrumentation is safe in tuberculous spondylitis. Conclusion: In the treatment of tubercular spondylitis by anterior decompression of the spinal cord and stabilization with grafting and instrumentation has significantly improved outcome with deformity correction as well, though no relation with the improvement in neurological status. The most important is thorough removal of all infective tissue and adequate decompression of canal.

941

P340: Spinal Tuberculosis: Our Experience

Kais Maamri ¹ , ines cherif ¹ , Mohamed Boukhit ¹ , Nessrine Nessib ¹ , Amine Trifa ¹ , Atef Ben Nsir ¹ , Mohamed Badri ² , and Mehdi Darmoul ¹

¹ Fattouma Bourguiba University Hospital, Neurosurgery, Monastir, Tunisia

² Trauma and Major Burns Center Ben Arous, Neurosurgery, Ben Arous, Tunisia

Introduction: Spinal tuberculosis is a destructive bone pathology. The spinal column is involved in less than 1% of all cases of tuberculosis (TB), but the increasing frequency of TB in both developed and developing countries has continued to make spinal TB a health problem. It accounts for approximately half of all cases of musculoskeletal tuberculosis and is more common in children and young adults. It can be associated with neurologic deficit due to compression of adjacent neural structures and significant spinal deformity. Therefore, early diagnosis and management of spinal TB has special importance in preventing its serious complications. Materials and Methods: We performed a retrospective study of a clinical serie including 8 patients with spinal tuberculosis treated between 2006 and 2019 in the department of neurosurgery of Fattouma Bourguiba University Hospital of Monastir Tunisia. In this study we aim to discuss the diagnosis and management of spinal TB based on a literature review. Results: Our serie included 3 males and 5 females. The age ranged from 39 to 57 years (mean 46.25). The average time to diagnosis from symptom onset was reported as 7.7 months. Local pain was the most common symptom (37.5%), then sciatica (25%) and heaviness in the lower limbs (25%). The lesions were located in cervical (1 case), thoracic (3 cases), lumbar (2 cases), sacral (1 case), lumbosacral (1 case) and thoracolumbar junction (1 case) spine regions. There were a case with bifocal lesion. MRI was performed in 87.5% and CT in 62.5%. All patients underwent an invasive procedure. A posterior approach was done in 7 patients (87.5%), and an anterior approach was required in the cervical case. We noted a single case of septicemia in a patient who was reoperated for the extension of the lesion. Postoperatively, significant symptom reduction was achieved with 6 patients and stabilization with 2 patients. Conclusion: In spite of the advancements made in early diagnosis and effective management, spinal TB continues to haunt medical professional due to parallel rise in drug-resistant strains. Surgery in spinal TB is directed toward achieving adequate decompression and debridement, maintenance, and reinforcement of stability. Spinal tuberculosis affects young people, so efforts should be made for its effective prevention.

Keywords

spinal tuberculosis, spondylodiscitis, Diagnosis, decompression, antituberculous treatment.

977

P341: Enhancing Spinal Tuberculosis Outcomes at a Tertiary Referral Center in North Sumatera, Indonesia

Arya Cipta Widjaja ¹ , Pranajaya Dharma Kadar ¹ , Otman Siregar ¹ , Heru Rahmadhany ¹ , and Benny Lay ¹

¹ Faculty of Medicine Universitas Sumatera Utara, Orthopaedic and Traumatology, Medan, Indonesia

Introduction: Spinal Tuberculosis (TB) pose a significant problem in Indonesia. With only few specialized spine surgeons available, the restraint access and affordability of health-care services by the majority of the population could have a major impact on the outcome. We investigated and analyzed the development of a strategy for improving outcomes in patients with spinal TB. Material and Methods: We presented a cohort retrospective study of 213 patients with spinal TB at Haji Adam Malik General Hospital, Medan between January 2015 and August 2019. Demographic data, clinical manifestations, laboratory data, imaging findings, treatment modalities, and outcomes were collected from the medical record. These data was then analyzed using corresponding bivariate study and predictors for spinal TB outcomes were determined using multivariate logistic regression study. Results: After 12 months, the number of patients, which showed good outcomes were 82% (151/184), while 18% (33/184) showed poor outcomes. Statistically, the presence of limb numbness (P = .001) and Erythrocyte Sedimentation Rate (ESR) level (P = .01) contributed significantly to unfavorable outcomes in spinal TB patient. The odds ratio (OR) was 31.6 and 1.16 for limb numbness and ESR level subsequently. However, limb weakness (P = .997), incontinence (P = .106), chronic cough (P = .704), thoracic (P = .844) or lumbal (P = .719) lesion on MRI, and PCR positivity (P = .132) were not significantly related to outcomes by multivariate regression analysis. Conclusion: Spinal Tuberculosis patients with elevated ESR level and numbness of the limb should be mindful of poor prognosis. The prevention and treatment of Tuberculosis in Indonesia remain a major challenge especially in rural and underdeveloped regions.

1059

P342: Tuberculosis of the Spine in Children: Does Drug Resistance Affect Surgical Outcomes?

Deepika Pinto ¹ , Arjun Dhawale ² , Ira Shah ³ , Avi Shah ¹ , Sarang Rokade ¹ , Kshitij Chaudhary ⁴ , Alaric Aroojis ¹ , Rujuta Mehta ¹ , and Abhay Nene ¹

¹ B.J. Wadia Hospital For Children, Orthopaedics, Mumbai, India

² Sir H.N. Reliance Foundation Hospital and B.J. Wadia Hospital For Children, Orthopaedics, Mumbai, India

³ B.J. Wadia Hospital For Children, Pediatrics, Mumbai, India

⁴ Sir H.N. Reliance Foundation Hospital, Orthopaedics, Mumbai, India

Introduction: This is a retrospective cohort study to compare the surgical outcomes of drug resistant (DR) and non-drug resistant (non-DR) spinal tuberculosis (TB) in children. Material and Methods: Radiographic and clinical data of children treated for spinal TB at a single center with minimum two-year follow-up were analyzed. Surgical outcomes in terms of neurological status and kyphosis angle at final follow-up, and complication rates were compared between DR and non-DR cohorts. Results: Forty-one consecutive children (mean age 8.5 ± 4.2 years, 20 boys, 21 girls) were treated for spinal TB with a mean follow-up of 31.2 ± 6.4 months. Fifteen were managed conservatively, of which only one had DR-TB. Of the 26 managed surgically, 13 were non-DR and 13 were treated for DR-TB. Drug resistance was diagnosed primarily on sensitivity testing and/or GeneXpert (eight cases); alternatively, when these were negative, it was diagnosed presumptively on the basis of inadequate clinical and/or radiological response to first-line anti- tubercular therapy (five cases). Neurological outcome was similar in both DR and non-DR groups. Kyphosis angle at final follow-up was significantly higher in DR compared to non-DR group, (mean 38.46+30.09° and 23.46+12.81° respectively, P = .04). Rate of post- operative complications was significantly higher in the DR group (38.4% vs 0%, P = .04). Complications included wound dehiscence, vertebral collapse, screw pull out and implant breakage. Conclusion: Children with spinal DR-TB were found to have poorer surgical outcomes, in terms of final kyphosis angle and rate of complications, as compared to non-DR cases.

1091

P343: Postoperative Fungal Discitis in Immune-Competent Patients; A Series of Five Patients

Jayesh Pawar ¹ , Dr Mihir Bapat ¹ , and Arpit Upadhyay ¹

¹ Nanavati Hospiatl, Spine, Mumbai, India

Introduction: Postoperative fungal discitis is a rare phenomenon and sparse data are available concerning the cause and adequate treatment guidelines especially in immune-competent patients. This case series reports fungal spondylodiscitis in five immunocompetent patients after minimal access spine surgery. Material and Methods: Retrospectively five patients with postoperative fungal discitis were studied. Spine radiographs, gadolinium contrast magnetic resonance imaging, and hematological markers (erythrocyte sedimentation rate/C-reactive protein) were performed in all patients. All patients underwent posterior debridement and stabilization procedure followed by antifungal therapy at our center. The clinical outcomes in the form of Oswestry disability index (ODI) and visual analog scale (VAS) scores were recorded before index surgery, 3 months, and at final follow-up. Results: All patients, four men and one woman with an average age of 55.2 years (45–61), had primary coincidental minimal access spine surgery. The average delay from the primary surgery to onset of pain was 6.4 weeks (4–10 weeks). The average delay from the onset of symptoms, postprimary surgery to secondary surgery, at the author’s institution was 13.2 weeks (11–16 weeks). Preoperative values of ODI and VAS were significantly decreased from 78.8 and 8.2 to 14.4 and 1.4, respectively, at the final follow-up. There was one case of recurrence at adjacent level 3 months after antifungal treatment requiring a revision surgery and recommencement of antifungal treatment. Conclusion: A high index of suspicion is required for prompt diagnosis. Fungal study should be routinely included in tissues biopsied for infective etiology. Antifungal treatment of adequate duration with surgical debridement and stabilization should be the mainstay of treatment.

1112

P344: Early MR Imaging During The Healing of Tuberculous Spondylodiscits Shows Paradoxial Worsening. Results of a Multi-Centre Serial Clinico-Radiological Study

J Naresh-Babu ¹ , Prudvi Kumar Reddy Kamazala ¹ , Ajoy P Shetty ² , Harvinder Singh Chhabra ³ , Shankar Acharya ⁴ , Janardhana Aitala ⁵ , and Shanmuganathan Rajasekaran ²

¹ Mallika Spine Centre, Spine Surgery, Guntur, India

² Ganga Hospital, Department of Orthopaedics and spine Surgery, Coimbatore, India

³ Indian Spinal Injuries Centre, New Delhi, India

⁴ Sir Ganga Ram Hospital, Department of Orthopaedic Surgery, New Delhi, India

⁵ Yenepoya Medical College, Department of Orthopaedic Surgery, Mangalore, India

Introduction: Spinal Tuberculosis is a medical disease and surgery is primarily indicated for complications like spinal instability/deformity and neurological deficit. The clinical healing of the disease doesn’t always correspond with radiological healing. Radiological worsening in-spite of clinical improvement creates dilemma in decision making especially in the early phase of the disease. Present study aims at identifying MRI changes in patients with spinal tuberculosis during early phase (<3 months) of anti-tuberculous treatment (ATT). Methods: A prospective Multicentre clinico-radiological study 34 (Cervical = 2, thoracic = 13, thoraco-lumbar = 2, Lumbar = 11, lumbosacral = 5 and skip lesion = 1) tuberculous spondylodiscitis patients on conservative management was carried out. All patients received standard four drug anti-tuberculous chemotherapy. All the patients were serially evaluated with pre-treatment, 1-month and 3-month MR images with concomitant clinical and laboratory parameters. The number of vertebrae involved, vertebral destruction (T1 signal hypointensity, T2 signal hyperintensity, bone marrow edema), intra osseous abscess, dural compression, disc space involvement, end plate destruction and pre/para vertebral collections were evaluated by two independent clinicians with significant expertise in spine surgery. Results: Mean age of the study group is 44.85 ± 16.47 with 19 males and 15 females. All patients showed progressive improvement in clinical and laboratory parameters during chemotherapy. Whereas there is a trend towards worsening of MR characteristics at one month followed by a trend towards healing at 3 months. Of the 34 patients, at one month there was progressive worsening in T1 hypo intensity in 30/34 (88.2%), T2 hyper intensity in 29/34 (85.3%), end plate involvement in 32/34 (94%), disc space changes in 33 (97%) Para/prevertebral abscess in 27(79.4%). Progressive destruction of involved vertebral body was observed in 32 of 34 patients with a minimum of 25% reduction in vertebral height. Number of involved vertebrae increased from a mean of 2.5 ± 1.1 to 2.58 ± 1.1 after 1 month and latter declined to 2.14 ± .96 at 3 months. All parameters showed relative improvement at 3^rd month follow-up MR images. Conclusion: The present Multi-centre study for the first time documented the serial MR imaging findings of healing spinal tuberculosis in the early phase. MR imaging in the early course of spinal tuberculosis may suggest worsening of disease in spite of good clinical response. Treating surgeon should be aware of these paradoxical worsening findings during the early course of the disease.

1130

P345: Surgical Management of Charcot Spinal Arthropathy Using a Quadruple-Rod Construct: A Proof of Concept

Alexander von Glinski ¹ , Christopher Elia ¹ , Dr. Sven Frieler ¹ , Darius Ansari ¹ , Clifford Pierre ¹ , Basem Ishak ¹ , Ronen Blecher ¹ , Bilal Qutteineh ¹ , Sarah Hopkins ¹ , Rod Oskouian ¹ , and Jens Chapman ¹

¹ Swedish Neuroscience Institute, Seattle, USA

Introduction: Charcot spinal arthropathy (CSA) is a relatively rare and consequently poorly understood destructive spine condition that affects patients with preexisting spinal cord injury; currently, there is no consensus in the literature regarding the most effective treatment methods. This neuropathic arthropathy may commonly be radiographically and clinically mistaken for a spinal osteomyelitis/discitis. A common confusion arises out of the question of presence of a spinal osteomyelitis /discitis which may be radiographically and sometimes clinically be confused with this neuropathic arthropathy. This is of importance in surgical decision making: in noninfected neuropathic arthropathies such as CSA, primary stabilization is the major goal, however, in the presence of a destructive spinal infection, staged surgery with debridement and subsequent reconstruction are prioritized. when tasked with deciding on a surgical reconstruction as presence of a destructive spinal infection with its emphasis on staged surgery with debridement and subsequent reconstruction is very different from that of a noninfected neuropathic arthropathy like CSA where primary stabilization is a major goal of surgery. Our study aims to investigate clinical and radiological outcomes of surgical treatment for CSA patients with and without concurrent spinal infections to optimize care. Material and Methods: Our single institution database was retrospectively reviewed for all patients diagnosed and surgically treated with CSA. These records were subsequently divided into two cohorts: patients who had spinal arthropathy complicated by infection and those without infection in the neuropathic region. These two cohorts were then comparatively studied for relative complications and the need for reoperation. Results: Overall, 15 patients with CSA underwent surgical intervention with a mean follow up time of 15.3 months (SD 13.3, range 0 - 43 months). 11 patients received stabilization with a quadruple-rod thoraco-lumbo-pelvic construct. 4 patients with superinfected CSA underwent a staged procedure. Patients treated with a staged approach experienced fewer intraoperative complications (0% vs 18%) and underwent fewer revision surgeries (25% vs 36%). Patients with and without presence of an identified spinal infection in the arthropathy had the same eventual healing. Conclusions: We found that surgical management in CSA patients with primary emphasis on stability and modified surgical treatment based on presence of an active infection in the zone of neuropathic destruction will lead to similar eventual succesful results with relatively few and manageable complications in this challenging patient population.

1210

P346: Pan Axial Skeletal Tuberculosis: A Rare Presentation

Nirdesh Hiremaglur Jagadeesh ¹ , Vikas Tandon ¹ , Abhinandan Reddy Mallepally ¹ , and Nandan Marathe ¹

¹ Indian spinal injuries center, spine services, New Delhi, India

Introduction: Tuberculosis is the one of the oldest disease which the mankind knows. Only 5-15% are symptomatic and rest of them have a latent infection. While spinal tuberculosis is a common form of musculoskeletal tuberculosis, rare presentations pose diagnostic challenges. In spine, thoracic and lumbar vertebra are more commonly involved followed by cervical vertebra. In most instances two are more adjacent vertebrae are involved as two adjacent vertebrae are supplied by single intervertebral artery. Nonetheless involvement of spine in a skipped manner is one of the type of atypical presentation which is misdiagnosed most of the time. Material and Methods: The present report describes an extremely rare case of pan axial skeletal tuberculosis with progressive paraparesis with bowel and bladder symptoms in a case of an 18-year-old boy who involving multiple segments of the spine (cervical, thoracic, thoracolumbar, lumbar, sacral vertebrae) with neurological deficit along with sternum and pelvis. Fixation was done from C5 to T5 with lateral mass screws in C5 and C6 and pedicle screws at other levels. Transpedicular decompression at T2 region decompressing cord from dorsal and ventral aspects was done. In thoracic region T7 to T8 instrumentation was done on the right side and T8 and T9 instrumentation on left side. There was complete destruction of lamina at T7-9 on left exposing the cord structure with granulation tissue directly. Decompression and posterior stabilization was done. In lumbar spine only posterior decompression in form of laminectomy at L3, L4 and L5 was done without any instrumentation. Results: Post operatively patient had an un eventful course in the hospital. He was mobilized on the post operative day 5. Patient regained power of key muscles to MRC grade 5 by the time of discharge. ATT was continued. At present follow-up patient is a walker with complete restoration of neurology including bowel and bladder recovery. Conclusion: Pan-axial spinal TB involving the whole spine extending to the pelvis is rarely reported in the literature. Early diagnosis by thorough clinical and radiological evaluation including a whole spine screening MRI would prevent catastrophic complications in these patients. Surgical stabilization and compliance with sensitive AKT forms the cornerstone of a successful outcome.

1227

P347: Spondylodiscitis of the Lumbopelvic Junction are at High Risk for Complications: What did we Learn from the Past?

Emre Yilmaz ¹ , Martin Hoffmann ¹ , Christiane Kruppa ¹ , Amir Abdul-Jabbar ² , Ahmet Oernek ³ , Chris Kaczmarek ⁴ , Christian Fisahn ¹ , Alexander von Glinski ¹ , Marcel Dudda ⁵ , and Thomas Schildhauer ¹

¹ BG University Bergmannsheil Bochum, Department of General and Trauma Surgery, Bochum, Germany

² Swedish Neuroscience Institute, Seattle, USA

³ BG University Bergmannsheil Bochum, Department of Radiology, Bochum, Germany

⁴ University Hospital Aachen, Aachen, Germany

⁵ University Hospital Essen, Essen, Germany

Study design: Single Center Retrospective Cohort Study. Objectives: To evaluate the rate of complications, microbial pattern, antibiotic treatment and outcome of patients undergoing lumbopelvic fixation in the treatment of lumbopelvic infections. Methods: From 2005 to 2013 a total of 16 patients (6m/10f) who underwent lumbopelvic fixation as single-stage procedure for spondylodiscitis were included. Indication, complication rates, microbial pattern, antibiotic treatment and outcome were recorded. Results: Mean age was 59.4 years (30-77 years). The causative organisms were, staphylococcus aureus (n = 4), MRSA (n = 4), microbacterium tuberculosis (n = 1), enterobacterium faecium (n = 1), and corynebacteria macglineyi (n = 1). All patients received antibiotic medication up to twelve weeks. Recorded complications included, three wound complications, three re-spondylodesis due to a pseudoarthrosis, one persistent infection and one patient died. Except one case with persistent infection no hardware loosening has been observed. None of the patients needed an additional anterior fixation. Five patients were included for follow-up (mean 27.8 months; 5.0-49.0 months). Three patients had a “good” and two patients a “excellent” outcome. The used antibiotic treatment in all cases would be different according to the current recommendations. Conclusion: We described a high-risk cohort and could show that the lumbopelvic fixation as single procedure is feasible in the treatment of spondylodiscitis of the lumbopelvic region. The lumbopelvic fixation technique represents a stable construct, which does not require an additional anterior fixation. Regardless of the used surgical technique an optimal antibiotical treatment is essentiell for treatment success. Global guidelines could support healthcare providers in the decision-making process to provide patients with the best possible treatment.

1246

P348: Percutaneous Biopsy in Spondylodiscitis, a Local Experience

Marcelo Ignacio Berrios Trucco ¹ , Álvaro Berríos ² , Damian Caba ² , Nicolas Lagos Parra ¹ , Camilo Manriquez ³ , Miguel Acuña ² , and Osvaldo Ojeda ²

¹ Hospital las Higueras, Orthopaedics and Traumatology, Talcahuano, Chile

² Hospital las Higueras, Spine Surgery, Orthopaedics and Traumatology, Talcahuano, Chile

³ Universidad de Concepción, Medical School, Concepcion, Chile

Introduction: Clinic, laboratory and magnetic resonance provides a high diagnostic suspicion on spondylodiscitis, though the gold standard for its confirmation is percutaneous biopsy. However, the current literature evidences a low performance of this procedure. The objective of this study is to evaluate the performance of percutaneous biopsy in our center. Materials and Methods: Observational, cross-sectional cohort study. The study population corresponded to patients over 18 years of age, diagnosed with Spondylodiscitis (clinical and magnetic resonance imaging), undergoing to a percutaneous biopsy and culture of vertebral platform under fluoroscopic guidance, by a member of the Column Surgery Team of Las Higueras hospital, between 2016 and 2020. The samples were sent for bacteriological study. Univariate analyses, qualitative variables (mean, standard deviation) and quantitative variables (frequency and percentage) were performed through STATA V.14 statistical software. Results: With a total of 24 samples studied, the average age was 61 years, 54,2% (n = 13) of the sample corresponded to women. 83,3% (n = 20) had chronic pathologies, highlighting hypertension and type 2 diabetes mellitus. In 25% (n = 6) positive pathogen was isolated. In 6 out of 24 patients, positive hemoculture (n = 3) and uroculture (n = 3) were obtained. There were no patients with biopsy and hemoculture/uroculture positive simultaneously. Despite these results, all patients were treated as spondylodiscitis due to high clinical suspicion and imaging (magnetic resonance imaging). Conclusion: Percutaneous biopsy is a significant element for diagnostic confirmation in patients with spondylodiscitis, though, a low probability to identify the causative microorganism is presented. The team can conclude that percutaneous biopsy is useful in identifying the specific microorganism for defining the antibiotic treatment (according to antibiogram), but it is not considered as essential for diagnosis when there is a compatible clinical picture and magnetic resonance imaging. If there are blood or urine cultures positive for typical spondylodiscitis germs, it can be concluded that a biopsy is not necessary.

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P349: Single-Stage Transverse Process Resection, Debridement, Interbody Fusion, and Internal Fixation for the Treatment of Lumbat Spinal Tuberculosis Via Posterior-Only Approach

Xiaoyu Cai ^{1 2} , Tao Xu ¹ , Yakefu Abulizi ¹ , Maierdan Maimaiti ¹ , and Weibin Sheng ¹

¹ First Affiliated Hospital of Xinjiang Medical University, Urumqi, China, Urumqi, China

² Saarland University, Homburg (Saar), Germany

Introduction: Spinal tuberculosis (TB) is a less frequently reported infectious spinal pathology. There are controversies on the surgical intervention of lumbar spinal TB with neurological damage and paraspinal abscess. This retrospective study was conducted to determine the effectiveness of single-stage transverse process resection, debridement, interbody fusion, and internal fixation for the treatment of lumbar spinal TB via posterior-only approach. Material and Methods: From January 2015 to June 2018, 32 consecutive patients (19 males and 13 females) with lumber spinal TB complicated with neurological damage and paraspinal abscess treated by single-stage transverse process resection, debridement, interbody fusion, and internal fixation were enrolled. Medical records, imaging studies, laboratory data were collected and summarized. Anti-TB drugs with HREZ chemotherapy regimen was administered to all patients. Surgical outcomes were evaluated based on visual analogue scale (VAS), American Spinal injury Association (ASIA) classification. The changes in C-reactive protein (CRP) levels, erythrocyte sedimentation rate (ESR), clinical symptoms and complications were investigated. Graft fusion was evaluated using Bridwell grading criteria. Results: The mean follow-up period was 20.41 ± 5.19 months. No implant failures were observed in any patients. Wound infection was observed in one patient. Solid bony fusion was achieved in 9 cases at 6 months and 23 cases at 12 months postoperatively. Kyphosis angle was 11.28 ± 4.01° at final follow-up. The levels of ESR and CRP were returned to normal at the final follow-up. VAS scores were significantly improved (P < .05). According to ASIA classification, 6 cases were classified as with grade D and 26 cases were classified as grade E at the last follow-up. Conclusion: Single-stage transverse process resection, debridement, interbody fusion, and internal fixation via posterior-only approach is a feasible and effective surgical therapy for lumbar spinal TB with neurological damage and paraspinal abscess.

1311

P350: Endoscopic Surgery of a Vertebro-Medullar Hydatidosis: A Case Report

Nessrine Nessib ¹ , Khalil Habboubi ¹ , Oussema abdelhedi ¹ , hassen makhlouf ¹ , Mahmoud Ben Messaoud ² , lanouar Bouzid ¹ , khalil ben hamida ¹ , Sofiene Bouali ² , and mondher mestiri ¹

¹ Kassab Institute, Tunis, Tunisia

² Neurosurgery Institute, Tunis, Tunisia

Introduction: Hydatidosis is a disease caused by a parasite called Echinococcus granulosus at its larval stage. This pathology is still endemic in several less developed countries. The infection permanently and gradually destroys the spine, which explains its discovery at the stage of complications, especially neurological. Treatment of echinococcosis remains primarily surgical despite advances in medical treatment. This surgery should aim for complete and large excision of the lesions as if they were a "malignant tumor". And the endoscopic technique, as we will present it in our case, is an interesting therapeutic option. Material and Methods: This a reported case. Results: We report the case of a 27-year-old man, of a rural origin, with a recurrent history of a vertebro-medullar hydatidosis, who was referred to our department for gait disorders and sphincter dysfunction made of bladder retention. On physical examination, muscle strength was weak in both lower limbs, deep tendon reflexes were exaggerated and the bilateral Babinski’s sign was positive. MRI of the spine showed a cluster of hydatid vesicles anterior to the spinal cord from D2 to D6 with signs of spinal cord compression. Our patient underwent a complete resection of the cysts via a posterior approach combining an open surgery to endoscopy. Post-operative course was uneventful. Neurological manifestations gradually improved and resolved after two months. Conclusion: Surgical treatment is necessary for the treatment of the hydatid cysts and the endoscopic assistance allows a considerable contribution by minimizing bone damage and maintaining spinal stability.

1336

P351: A comparison of Biofilm Formation on Medical Implants

Yasmin de Rezende Beiriz ¹ , Amanda Grippa Piffer ¹ , Bil Bassetti ¹ , Rodrigo Moraes ¹ , Igor Machado Cardoso ² , José Lucas Batista ² , and Charbel Jacob Jr ¹

¹ Escola Superior de Ciências da Santa Casa de Misericórdia de Vitória (EMESCAM), Vitória, Brazil

² Hospital Santa Casa de Misericórdia de Vitória, Vitória, Brazil

Introduction: The species P. aeruginosa is an aerobic Gram-negative bacillus belonging to the bacterial family Pseudomonadaceae, with oxidative metabolism and optimum growth temperature between 37 and 42° C. Its infections predominate in critically ill and immunocompromised patients. Studies in several countries show the presence of multi-resistant Pseudomonas aeruginosa antimicrobials causing nosocomial infections. The risk of infection vary with the type of prosthesis due to increased susceptibility to biofilm formation. In general, orthopedic spinal implants are composed of polymers or metal alloys, and the latter requires a higher bacterial concentration for the development of infections. Another widely used material for performing interbody arthrodesis in spinal surgery is polyetheretherketone (PEEK), a biomechanically hydrophobic polymer similar to cortical bone. Among many bacteria involved in biofilm studies, Pseudomonas aeruginosa and Staphylococcus aureus stand out. Studies comparing titanium alloy with cobalt chromium and PEEK showed that titanium alloy has a lower level of bacterial adhesion. This work aims to identify the development of the strong biofilm-producing bacterium Pseudomonas aeruginosa in Titanium rod and PEEK cage. It also aims to characterize the sample whose bacterial development occurred early. Material and Methods: This is a longitudinal study of quantitative approach, carried out in the EMESCAM Microbiology Laboratory. The amount of biofilm formed will be evaluated by culturing the samples of titanium rods and PEEK cage, based on the amount of Pseudomonas aeruginosa, the main biofilm-forming bacteria used in the laboratory, composing the sample biofilm. The study was performed in triplicate. It was agreed that the bacteria would be in contact with the alloys for 17 hours and 1 week. Results: Based on these results, it is possible to infer that the absorbance value, that is, the amount of biofilm is not representatively different, comparing the time variable in both materials. Conclusion: Considering the same material, there was no difference in biofilm formation at 17 hours and 1 week. Furthermore, it can be concluded that there was no difference in biofilm formation in titanium rods incubated for 17 hours and in PEEK cages during the same period.

1376

P352: Pre and Post-Operative Spine Balance Evaluation in Acute Pott's Disease

Amin Henine ¹

¹ University Center Hospital of Douera, Medical School University of Blida 2 Algeria, Orthopaedic A Department, Algiers Algeria, Algeria

Introduction: The risk of malalignment should not be ignored during the Pott’s affection in its installation phase. Severe defects can cause kyphosis and even paraplegia which can ultimately leave serious after-effects. Our work is aimed to study the impact of spinal tuberculosis on sagittal alignment of vertebral column and the place of the osteosynthesis in its maintenance in early tuberculosis spinal disease. Material and Methods: A retrospective review of 21 patients from 2012 to 2018, 19 females and 2 males, with an average age of 42 years (range 19 and 67), and concerning the location, we had 2 cervical, 8 thoracic, 7 thoracolumbar and 4 lumbar. All were instrumented and fused. Measurements were made on x-rays of the entire spine extended to skull and knees, in front and lateral views. Varieties were typed according to Roussouly’s classification. Local kyphosis (LK), and regional kyphosis (RK), were measured. Cervical lordosis (CL), thoracic kyphosis (TK), thoracolumbar interval T10-L2, lumbar lordosis (LL), sagittal tilt of T9 and that of T1, were assessed. Pelvic incidence (PI), sacral slope (SS) and pelvic tilt (PT), were also calculated. The SRS-Schwab classification of adult spinal deformity was used for the assessment of pelvic spinal harmony (PI-LL), sagittal alignment (SVA) and pelvic retroversion (PT). Results: We noted an improvement of LK, from 28.3 ° ± 16.3 (8 °∞72 °) to 20.7 ° ± 13.5 (5° ∞52 °) and for RK, from 26.7 ° ± 20.5 (-28 °∞63 °) to 18.2 ° ± 19.0 (-22 °∞54 °). CL remained constant, 18.57 ° ± 6.4 (0∞26 °). TK subjected to minor variability, from 44.57 ° ± 11.4 (26 °∞ 72 °) to 45.09 ° ± 11.5 (26 °∞72 °). T10 L2 ameliorated from 14.5 ± 9 (0 ∞44 °) to 12.6 ± 7.8(0∞44 °). LL, 41.9 ± 15.9 (10°∞66 °) to 42,8 ± 15,2 (10°∞66 °). T9 tilt remained within standards, from 12.4° ± 4.8 (-4°∞20 °) to 12,9 ± 2,9 (6°∞18°) and it was the same for T1 tilt from 4,1 ± 6,0(-14°∞10°) to 4.3° ± 3.8 (-6°∞10 °). PI was moderate and constant, 49.3 ± 9.1 (28 °∞62 °). SS was little bit affected from 32.7 ° ± 8.7 (16°∞50 °) to 35.0 ° ± 8.9 (20°∞54 °). PT improved from 17.1 ° ± 6.4 (10 °∞30 °) to 14.4 ° ± 5.8 (6°∞26 °). The 4 types of spine described by Pierre Roussouly were present. PI-LL was maintained normal, from 7.4 ° ± 11.9(-8°∞40 °) to 6.6 ° ± 11.1 (-8°∞40 °), SVA too, from + 1.2 ± 5.1 cm (-11.2cm ∞+13.5 cm) to + 2.3 ± 5.1 cm (-11.4 cm ∞+15.3 cm), and PT was preserved as it has been shown above. Conclusion: Surgery by fixation and fusion of early spinal tuberculosis preserves or restores better the spinal balance which is still not too disturbed.

1382

P353: COVID-19 Second Look

Agustin Tellez Duarte ¹ and Laura Virginia Gonzalez Ramirez ²

¹ Excelencia Médica, Spine Surgery, Cozumel, Mexico

² Excelencia Médica, Rheumatology, Cozumel, Mexico

Introduction: Objectives: It is to determine in Orthopedic surgery and Spine Surgery and it´s branches the new required safety protocols when attending patients with risk of infection, or transmission for COVID-19 and comorbidities in the outpatient and inpatient hospital setting. COVID-19 is also known as SARS-Cov-2 or HCoV-19; all these names define the same virus which is a Beta-Corona Virus that belongs to the RNA encapsulated family of viruses. The Covid-19 disease is a pandemic disease which is presenting a high mortality rate, a lot of it´s effect on the lungs and upper respiratory system has been analyzed, but little about the multiorgan consequences, its capability to survive on surfaces in the outer environment like metal, plastic and cardboard. More recent research shows that COVID-19 attaches to the Orf8 protein affecting hemoglobin, and also may cause ICD, when this happens a multiorganic failure may present. This may be preventable by antitrombotic treatment during hospitalization and prehospitalization of patients. This Capsule is formed by lipopolysaccharides and a lipid layer which gives the virus it´s capability to adhere to cells and Attach to them transmitting their RNA in to the cell for viral proliferation. The adherence peculiarity of this virus is shared with it´s common kind SARS-CoV-1. The viral capsule is also the viruses weakness due to it´s inability to survive for long periods of time in the environment, and it´s weakness to all saponifiable substances like soap an alcohol. Recommendation for close supervision of prostetic devises and their maintenance is recommended. Material and Methods: Study Design: This is a systematic literature review for COVID-19, SARS-CoV-2 with Orthopedic and Spine Surgery relevance of 25 recent publications and studies. Results: Recent knowledge for this disease has changed the Virus affects Orf-8 protein of the Hemoglobin destroying B-Hemoglobin, and IDC (intravascular disseminated Coagulation) is found to happen in many patients, together with it´s capsular capability to adhere to metallic and plastic surfaces, pneumonic pattern associated with ventilator use, and the relapse in some patients, changes the view, preventative measures and treatment of this disease. Publication of global statistics show that patients during spine surgery procedures with Hypertension tend to have a higher rate of suffering the disease. Some new measures are proposed. Conclusion: New care guidelines for COVID-19 patients are proposed based on the new research on SARS-COV-2 clinical pathologic findings are necessary.

1383

P354: COVID-19, SARS-CoV-2 Encapsulated RNA Virus is Capable of Forming a Viral Biofilm

Agustin Tellez Duarte ¹ and Laura Virginia Gonzalez Ramirez ¹

¹ Excelencia Médica, Spine Surgery, Cozumel, Mexico

Introduction: The COVID-19, SARS-CoV-2 is an encapsulated RNA virus, this capsule is made from a lipid layer with Proteins on its membrane. Lipid membranes tend to have a “soap bubble” like property when they are together forming very frail membranes, with enough energy to protect the membranes in the middle, this property allows the viruses to float in the air, and attach to surfaces, if the virus were single with no poli-viral support these would not be able to survive in this conditions. Transmission during spine surgery may be prevented by making a good air and physical transmission prevention protocols. One cervical spine patient operated under emergency condition during COVID pandemic was treated successfully during a 60 day hospitalization period in a COVID Hospital without infection. Material: SARS-CoV-2 rapid test + PCR SARS-CoV-2 test on the patient and family members, Electronic Microscopy publications + Viral Membrane publications. Study Design: An observational prospective study of one high risk of infection patient was done, This is a systematic literature review for COVID-19, SARS-CoV-2 with Orthopedic and Spine Surgery relevance of 25 recent publications and studies, and a mathematical hypothetical calculus. Results: The SARS-CoV-2 virion, 50 − 200 nm in diameter, contains four structural proteins, known as the S (spike), E (envelope), M (membrane), and N (nucleocapsid) proteins. The S protein, imaged at the atomic level using Cryo-EM, is responsible for the attachment and fusion of the viral and host-cell membranes. This process is triggered when the S1 subunit of S protein binds to a host-cell receptor. To engage a host-cell receptor, the receptor-binding domain (RBD) of S1 undergoes transient hinge-like conformational motions (receptor-accessible or receptor-inaccessible states). The angiotensin-converting enzyme 2 (ACE2) is the host cellular receptor with a higher affinity to SARS-CoV-2 than to SARS- CoV. In the recognition of RBD, the protease domain (PD) of ACE2 mainly engages the α₁ helix with a minor contribution from the α₂ helix and the linker of the β₃ and β₄ sheets. The interaction between this residues by vdW energy given by the NAMD energy plugin is: Leonard Jones (L J) potential energies are used to describe the vdW interactions and close distance atomic repulsions¹: All of the previous information allows us to suspect that interviral membrane activity is present to, leading to think in a possible Viral Biofilm may exist, and the destruction of this membrane may lead to viral isolation and a shorter viral life spam. This also helps the virus infect other tissues, like erithrocytes, liver celles, neurons, nephrons, etc.². Conclusion: SARS-CoV- 2 is able to survive and spread because of this membrane characteristic of the virus, in spine surgery to comply with protection protocols may prevent spine surgery infection by this virus.

1465

P355: Checking Residual Protein on Surgical Instruments After Washer Disinfector Process in Brazilian Hospital CSSD using ProReveal high tech

Regina Maria Barretto Cicarelli ¹

¹ UNESP - Faculdade de Ciências Farmacêuticas, Araraquara - São Paulo, Brazil

Introduction: Contamination of instruments in surgeries is an extremely important issue in Public Health, especially in cases of orthopedic implants and mainly on neurosurgeries. Until the 1940s, in the USA, surgical medical supplies were mostly processed and maintained in the departments and patient care are as where they were to be used. Under this system, there has been considerable duplication of efforts and equipment, and it is therefore difficult to maintain consistently high standards for sterilization technique and product quality throughout the health care facility¹. Brithish Standards Institution (BSI/ISO) establishes the conditions for treatment and sterilization of surgical instruments and implants, recommending the evaluation of the efficiency and effectiveness of the whole decontamination process, taking into account patient safety². In Brazil, regarding the reuse of instruments in different surgeries, CME (Sterile Material Center) and OPME (Orthopedics, Prostheses and Special Materials) in healthcare public and private hospitals must follow the recommendations of RDC15/2012 established by the National Health Surveillance Agency (ANVISA)³ and ABNT NBR ISO 14971, 2ª edition (27/10/2009). The evaluation of the efficiency and effectiveness of the decontamination process is carried out in the daily routine of CME/OPME monitored only by physical, chemical and biological indicators, whose standards must be evaluated quarterly, according to with the Portaria MS nº 2914/2011⁴, instead also evaluating randomly some instrument samples to check for disinfection process. It is a common sense that inadequate decontamination treatments can cause irreversible damage to the materials, considerably reducing their half-life of use, and also can be a vehicle of contamination to patients. In this scenario, there is a need for review and adaptation of the current method used in Brazil for decontamination processes, bringing them closer to the international standards. Recently, we published a research showing the high number of bacterial CFU (colony forming unit) on instrument surface after decontamination process just before sterilization⁵. The objective of this work was to demonstrate the use of the ProReveal^® methodology⁶ in the assessment of residual protein on instrument surfaces which would be a risk to damage the patient after spine surgeries. Material and Methods: Surgical instruments were selected after washer disinfector process at CME in a hospital in São Carlos-SP city and checked for presence of residual protein using ProReveal. Results: Testing four different cleaning conditions including post sterilization it was detected the following distribution of protein quantification (32 instruments in total): 9.375% > 5.0 μg (the contamination limit fail is 5.0μg); 18.75% > 3.0 μg; 12.5% > 2.0 μg; 6.25% > 1.0 μg; 17.75% < 1.0 μg; 15.625% = 0 μg. Conclusion: From 32 instruments, three of them showed a higher amount of protein (> 5.0μg) than expected failed the test, meaning 37.5% considering the batch of eight instruments. All these results will be presented and discussed in oral/poster presentation.

References

1. www.urmc.rochester.edu/sterile.aspx.

2.www.gov.uk/government/collections/health-building-notes-core-elements.

3.http://bvsms.saude.gov.br/bvs/saudelegis/anvisa/2012/rdc0015_15_03_2012.

4.http://bvsms.saude.gov.br/bvs/saudelegis/gm/2011/prt2914_12_12_2011.

5.http://prodsaude.org.br/o-papel-da-desinfeccao-dos-instrumentos-cirurgicos-na-prevencao-da-transmissao-de-infeccao-hospitalar/.

6. http://synopticshealth.com/proreveal-test/.

1486

P356: Clinical Outcomes of 24 Cases of Cervical Pyogenic Spondylodiscitis

Yoshifumi Kudo ¹ , Yushi Hoshino ¹ , Ryo Yamamura ¹ , Akira Matsuoka ¹ , Hiroshi Maruyama ¹ , and Chikara Hayakawa ¹

¹ Showa university, Orthopedic surgery, Shinagawa-ku, Japan

Introduction: Occurrence of infection in the cervical spine is relatively rare (5∼20%). But, in contrast with other locations of spinal infections, cervical pyogenic spondylodiscitis (CPS) can be a much more dramatic and rapidly deteriorating process, leading to early neurologic deficit. The purpose of this study is to investigate the patients of CPS and evaluate their clinical outcomes. Materials and Methods: We retrospectively reviewed patients who were hospitalized and had treatment for pyogenic spondylodiscitis in our institution between January 2000 and December 2018. We included patients who had cervical involvement with minimum follow up > 6 months for analysis. We excluded patients with only epidural abscess without radiological change in CT or MRI in vertebral body, disc, and endplate. Data were analyzed regarding prevalence, affected level, diagnosis at admission, the days necessary for leading to diagnosis from the onset, causative organisms, epidural abscess, neurological deficit (Frankel’s classification), surgical approach, radiological assessment (change of the local alignment in affected level) and clinical outcomes. Results: There were 312 patients who were hospitalized in our institution in that period. A total of 24 (7.7%) patients with a mean age of 62.6 years were involved in this study. C5/6 is the most affected level followed by C4/5 and C6/7. Diagnoses except for cervical spondylodiscitis like meningitis and cerebral infarction at admission were 11 cases (46%). In 10 cases, it took more than 30 days to reach the correct diagnosis (average 50.4days). Epidural abscess were detected in 18 cases (67%). Twenty one patients (87.5%) presented with varying degrees of neurological impairment. Nineteen patients (79%) underwent surgery, anterior decompression and fusion (6 cases), anterior abscess drainage and posterior decompression and fusion (2 cases), anteroposterior decompression and fusion (11cases). 2 cases of anterior fusion required additional posterior fusion because of non-union, therefore 13 cases (68%) needed anteroposterior fusion and instrumentation surgery was performed in 16 cases (84%) at last. In 5 cases, surgical treatment was chosen due to kyphotic deformity, residual pain and paralysis after conservative treatments were failed. Healing of infection was achieved in all cases. Interval to negative CRP was 27 days average. Kyphotic deformity at affected level was corrected from -13.6°to -.2°in surgically treated patients, while worsened from -2 to -7.8 in patients with conservative treatment. Conclusion: In this study, cervical involvement was only 7.7% in all patients with pyogenic spondylodiscitis. However, most of them showed neurological impairment (87.5%) and required surgical treatment (79%). Moreover, diagnosis at admission were incorrect in most of the cases, the difficulty of diagnosis might be related to serious condition. In case such as kyphotic deformity and neurological impairment, surgeons should take surgical options in to consideration soon after diagnosis.

1498

P357: Tuberculosis of the Craniocervical Junction: A Case Report

Ines Cherif ¹ , Fatma Kolsi ¹ , Omar Hattab ¹ , Firas Jarraya ¹ , Brahim Kammoun ¹ , and Boudawara Mohamed Zaher ¹

¹ Habib Bourguiba University Hospital, Department of Neurosurgery, Sfax, Tunisia

Introduction: Tuberculosis (TB) of the craniocervical junction is rare even where the condition is endemic. It occurs in 1–5 % of cases of TB spondylitis and poses problems in both diagnosis and management. This can be a life-threatening condition due to mass effect of infective process or resultant instability, so that it must be diagnosed early and treated promptly. Death is usually due to atlantoaxial dislocation causing compression of the cord. Surgical indications for TB of craniocervical junction are not clear from literature. Materials and Methods: We describe a case of a patient with craniocervical junction tuberculosis followed in our department from 2011 to 2013 in order to identify its neuroradiological particularities. Case Report: A 19 years-old patient who presented neck pain since 2 months, resistant to analgesics. The neurological exam found restricted rotation of the neck, with or spasmodic tilting of the head. The erythrocyte sedimentation rate was 80 at the first hour. The X-ray of the cervical spine showed an atlantoaxial dislocation. The CT scan showed a lytic process of the axis with a compressive collection. The cervical MRI confirmed the total destruction of the body and the lateral masses of the axis with a huge collection involving C1 and C2 with anterior and posterior extension. Peroral incision of the retropharyngeal mass was performed. Thick yellow pus was aspirated, necrotic tissue was curetted, and multiple tissue biopsies were obtained. Histological exams confirmed the diagnosis of tuberculosis and the was treated by immobilisation and antitubercular therapy for 12 months. At the end of the treatment, the CT scan and the MRI showed good ossification and disparition of the collection. Clinically the patient was off any neurological signs. Conclusion: Although craniocervical junction TB is a rare disease, the outcome of treatment is good. Antituberculous drug therapy remains the mainstay of treatment after confirming the diagnosis. The surgical management options include transoral decompression with or without posterior fusion, depending upon the presence and persistence of atlantoaxial instability.

1610

P358: Hydatidosis of the Spinal Column: Tunisian Series and Review of the Literature

Yassine Gdoura ¹ , ines cherif ¹ and Boudawara Mohamed Zaher ¹

¹ Habib Bourguiba Hospital, Neurosurgery, Sfax, Tunisia

Introduction: Hydatid disease is a parasitic infection which can infect humans through the larval stage of the Echinococcus Granulosis (EG). It’s commonly seen in the Mediterranean region, Middle East and India. Hydatid cysts are frequently formed in the liver (60-70%), then the lungs. Although, bone involvement is rare with approximately 0.5% of all hydatid cyst cases residing in the vertebrae. We report a series of spinal column hydatid cyst, treated over a period of 16 years. This study aim to discuss the diagnosis and the management of spinal hydatid cyst, based on a literature review. Materials and Methods: We report a retrospective study of 7 cases of spinal column hydatid cysts treated in the neurosurgery department of Habib Bourguiba University Hospital of Sfax-Tunisia, between January 2003 and December 2018. Results: It’s about 3 males and 4 females aged from 7 to 66 years with a mean age of 36,8. The revealing clinical symptomatology was spinal cord compression, back pain and sciatica. Weakness of the lower limbs was found in 4 cases. We found bowel and bladder dysfunction in 57.1% of the patients. Whole spine MRI was done in all cases. Hydatid cysts were localized in dorsal column in 3 cases, dorsolumbar junction in 1 case, lumbosacral vertebrae in 1 case and lumbar column in 2 cases. All the patients were operated and treated with antihelminthic (Albendazole). Posterior approach was performed in 5 cases. The two other patients were operated through a lateral and an anterior approach. 5 patients had good recovery of muscle strength and resolution of limb sensory disturbance. The evolution was marked by relapse in 3 cases, which were reoperated. The average follow-up of patients after surgery was 6.3 years. Conclusion: Spinal hydatid cyst is a serious disease with significant morbidity. The recommended treatment is surgery with anterior or posterior approach and subsequent adjuvant medical therapy. The results are rarely satisfactory and the prognosis is usually poor due to the frequency of relapses.

Keywords

echinococcosis, spinal hydatid cyst, surgical treatment, Albendazole

1634

P359: Multiple Multiresistant-Agent Infection After Instrumented Spine Surgery - A Multidisciplinary Challenge

Francisco Xará-Leite ¹ , Ana Ribau ¹ , Miguel Araújo Abreu ² , and Ricardo Rodrigues-Pinto ^{3 4}

¹ Centro Hospitalar Universitário do Porto, Orthopaedics, Porto, Portugal

² Centro Hospitalar Universitário do Porto, Infectious Diseases, Porto, Portugal

³ Centro Hospitalar Universitário do Porto, Spinal Unit (UVM). Department of Or-thopaedics., Porto, Portugal

⁴ Instituto de Ciências Biomedicas Abel Salazar, Porto, Portugal

Introduction: Multidrug-resistant (MDR) pathogens have become responsible for an increasing part of nosocomial infections over the last two decades.1 Among their vast array, carbapenem-resistant Enterobacteriacae (CRE), and particularly Klebsiella Pneumoniae (CRKP) have received widespread attention, due to a rapid increase in prevalence all over the world.2 They represent a particularly worrisome public health threat since infection by CRKP has been shown to double the mortality rate (42%) relative to carbapenem-susceptible Klebsiella Pneumoniae (CSKP, 21%).2 Vancomycin-resistant Enterococci (VRE), although described several years ago, also show an increasing trend, with our country having one of the leading rates of VRE isolation in the world.1,3 Long lengths of hospital stay (LOS), admission to the intensive care unit (ICU), previous exposure to antibiotics (particularly carbapenems, but not exclusively) and surgical re-interventions are among the well-established risk factors for the development of both CRKP and VRE infections.3,4. Material and Methods: We report the case of a patient with consecutive isolations of several multidrug-resistant agents from a wound infection of instrumented lumbar spine surgery, successfully treated with novel antibiotics in combination therapy. Several of the key-decisions made by our multi-disciplinary infection team along this lengthy therapeutic process are debated, their rationale put forward and critically analyzed. Results: A 63 year-old female with lower limb radiculopathy was subject to an L5-S1 TLIF, but consecutive complications (including shingles, acute infection subject to DAIR procedures and chronic infection leading to implant removal, fungemia and, finally, SARS-CoV-2 respiratory infection) led to a total 181 days of hospitalization (plus 18 days of home monitor-ing) and a cumulative 459 days of antimicrobial therapy, with need for several different regimens and innovative therapeutic strategies, some of which have only recently been described and approved. Eventually, after recurring to a novel antibiotic alternative, infection was controlled and the patient is pain-free. The critical steps of this process will be individually scrutinized in our presentation. Our objective is to backtrack this complex story and understand if our decisions could have been made in a more timely manner or even in a different direction all-together, so our future processes as a team can be fine-tuned and continue to im-prove in favor of our patients’ well-being. Conclusion: Multidrug resistance has become a major challenge in today’s medicine. Extreme care should be taken to avoid their emergence, but when present a multi-disciplinary approach has become mandatory to ensure clinically up-to-date treatment choices. Multi-modal antibiotic schemes tend to show the most promising results, with which successful infection resolution can still be achieved.

References

1. Point prevalence survey report: Acute care hospitals. https://www.ecdc.europa.eu/en/healthcare-associated-infections-acute-care-hospitals/surveillance-disease-data/report. Accessed August 30, 2020.

2. Xu L, Sun X, Ma X. Systematic review and meta-analysis of mortality of patients infected with carbapenem-resistant Klebsiella pneumoniae. Ann Clin Microbiol Antimicrob. 2017;16(1). doi:10.1186/s12941-017-0191-3

3. Cetinkaya Y, Falk P, Mayhall CG. Vancomycin-resistant enterococci. Clin Microbiol Rev. 2000;13(4):686-707. doi:10.1128/CMR.13.4.686-707.2000

4. Liu P, Li X, Luo M, et al. Risk Factors for Carbapenem-Resistant Klebsiella pneumoniae Infection: A Meta-Analysis. Microb Drug Resist. 2018;24(2):190-198. doi:10.1089/mdr.2017.0061

1822

P360: Intra Dural Extra Medullary Tuberculoma of Dorsal Spine: Case Report and Systematic Review of Literature

Christopher Gerber ¹ , Anindya Basu ¹ , and Selvin Vijayan ¹

¹ I-NK Istitute of Neuroscience, spine surgery, Kolkata, India

Introduction: The prevalence and incidence of systemic tuberculosis increased in the last decade. About 10% of those with tuberculosis have Central nervous system involvement. Most of them present as Potts abscess, non-osseous tuberculoma are rarity. Non-osseous spinal cord tuberculomas can be either extradural, intradural extramedullary, or intramedullary lesions. Only 2%-5% of CNS tuberculosis is intradural and 1% among them is intradural extramedullary tuberculomas. We present 2 such patients presenting with features of dorsal myelopathy. We give a brief report on these patients presentation, findings and management. Materials and Methods: The first patient was a 52 years male with associated diabetics, had history of fever for 5 months. Initially he was treated elsewhere with anti-tubercular drugs on suspicion of spinal tuberculosis based on MRI findings. 2 months after starting anti tubercular drugs he developed weakness of both lower limbs. He presented to us with progression of weakness, inability to walk and urinary incontinence. The second patient was a 50 years old female with a complaints of back pain and bilateral leg pain with tingling for 45 days. Initially she was started on anti-tubercular drugs elsewhere suspecting spinal tuberculosis based on MRI findings. While on anti-tubercular drugs, she developed weakness of both lower limbs. She presented to us 45 days later with progressing weakness and increasing difficulty to walk and recent onset of urinary symptoms. In both the patients investigations were performed which suggested as intradural extramedullary tuberculoma. They were managed surgically. Procedure performed included laminoplasty, duroplasty and debulking of granulation tissue with sampling for biopsy and culture tests. They were continued on anti-tubercular drugs following surgery. At the latest follow up of 6 months post surgery first patient did not show significant improvement of neurological status. On the other hand the second patient had significant improvement and was able to walk with support. Results: Tuberculosis infection involving the spine may be classified as Pott’s spine, Pott’s paraplegia, tuberculous arachnoiditis, nonosseous spinal tuberculoma (extradural, intradural extramedullary, intramedullary), and spinal meningitis. A systematic review of literature using Pubmed search engine was done. A total of 26 such reported cases in English literature from 1984 to present were found. The results have been compiled and our reported cases have been compared to them. Conclusion: Intradural extramedullary tuberculomas of the spinal cord should be considered in the differential diagnosis of subacute compressive myelopathy in a relatively young patient, even more when there is associated history of pulmonary tuberculosis or tubercular meningitis. An early MRI imaging helps in early diagnosis. They are insidious in onset, slowly progressing in spite of adequate antituberculous treatment thus requiring surgical management in most. The goal of surgery is decompression. These patients have a good neurological outcome if surgery is performed early, more so when there is deterioration of a patient in spite of conservative management with anti-tubercular drugs.

1827

P361: Purulence of a Neglected Thoracic B2/A0 Fracture Accompanied With Incomplete Paraplegia in a Previous Immunocompetent Patient With Ankylosing Spondylitis

Ioannis Papaioannou ¹ , Stamatia Chatziperi ¹ , Thomas Repantis ¹ , Andreas Baikousis ¹ , and Panagiotis Korovessis ¹

¹ General Hospital of Patras, Orthopedic, Patras, Greece

Introduction: It is well known that in ankylosing spondylitis the spine become rigid, without movement and finally ends up with osteopenia and vulnerability even to minor trauma. Neglected spinal injuries are defined as injuries not treated timely and many complications and treatment challenges can arise. Material and Methods: We present a unique case of a 70-years-old male patient with a neglected Th10 chance fracture presented with incomplete paraplegia. The patient’s medical history included prostate hyperplasia, obesity and arthitis of hip and knee joints. Our patient had a minor trauma 35 days before admission, but he never asked medical counselling. 8 days before admission he complained for severe pain of his right knee. The orthopedic surgeon treated him for the knee osteoarthritis with intra-articular injection of hyaluronic acid plus per os corticosteroids (methylprednisolone 16mg once a day) and paracetamol. The pain became worse, while two days after the patient had weakness of his right leg and subsequently the left one. One day before admission the patient had urinary retention and was also unable to control defecation. The neurological examination on admission revealed sensory deficit below Th10 level (both sides pin prick and light touch were 1/2) and absent motor function of both lower extremities. Anal sphincter was spoiled, while urinary retention was confirmed via bladder ultrasound. After radiographic evaluation, a computed tomography was performed, while the patient didn’t manage to undergo MRI examination due to his obesity. Laboratory results revealed increased values of glucose (227 mg/dl), creatinine (3,4 mg/dl), WBCs (11,5 K/μl), CRP (15,5 mg/dl) and ESR (30 mm/h). Results: Based on the glucose and HbA1c values the diagnosis of diabetes mellitus type 2 was settled. The patient underwent posterior decompression of Th10 vertebrae and stabilization via pedicle screws from Th7 to L1. During the decompression the major surgeon noticed purulence and extensive debridement was performed. Body temperature was within normal limits, while the blood cultures were always negative. The cultures of the Th10 revealed Enterococus sp, while the same pathogen was developed to urine cultures. Based on these findings we postulate that the vertebrae osteomyelitis occurred via the Batson plexus. We believe that obesity, the undiagnosed diabetes mellitus and the cortisone administration contributed to the development of this spinal infection. The patient received intravenous antibiotics for 4 weeks, until CRP and ESR to return to normal values. He was discharged with per os antibiotics for two months with monthly evaluation. Neurologic evaluation before transferring to the rehabilitation center revealed improvement of the motor function (bilateral 3/5 MRC L5, S1). Conclusion: Based on the current literature the recorded complications resulting from the delay in diagnosis and subsequently appropriate treatment are the following: bed sores, back pain, constipation, residual kyphotic deformity, urinary tract infection. Depression, deep vein thrombosis, joint contractures, paralytic ileus respiratory tract infection and calculi formation in kidney or bladder. There is no mention of infection of the fractured site. Osteomyelitis should be considered as a possible complication of the neglected thoracolumbar fractures, especially in high risk patients with immunosuppression.

1832

P362: A Rare Case of Voriconazole Induced Vertebral Periostitis in a Patient With Invasive Aspergillus Spondylodiscitis

Alok Jain ¹ , Shekhar Y Bhojraj ² , Premik B Nagad ² , and Aditya Kashikar ²

¹ lilavati Hospital and Research Center, Spine Surgery, Mumbai, India

² lilavati Hospital and Research Center, Mumbai, India

Introduction: Spondylodiscitis due to invasive aspergillosis is a rare condition and usually occurs in immunocompromised subjects. The recommended first line therapy for treatment or prophylaxis for such invasive aspergillosis is long term Voriconazole. Long term Voriconazole treatment is associated with multiple adverse effects, of which painful periostitisis one of the recently reported rare complication. This condition commonly affects clavicles, ribs, scapula, acetabulum, and hands. Till date, vertebral periostitis as an adverse effect of voriconazole therapy has not been described. To our knowledge, it may be the first case of voriconazole-induced periostitis in an immunocompetent patient with known case of invasive aspergillus spondylodiscitis under treatment. Material and Methods: We describe a case of 66-year-old male patient who presented with severe mid backache and mild to moderate left gluteal and thigh pain for the past 9 months. Neurologically, there was no motor or sensory deficit. MRI imaging showed multi-level Dorsal spine spondylodiscitis (maximum lesion at D9 – D10) with no cord compression. Two consecutive CT guided biopsies of the lesion proved inconclusive. Henceforth D9- D10 hemilaminectomy with open biopsy was performed. Fungal culture came positive with growth of Aspergillus flavus and histopathological KOH stain showing septate fungal hyphae. Patient was started on long term oral tablet Voriconazole 200 mg twice daily. Gradually, patient showed clinical, serological and radiological improvement. However, by the end of 9 months of treatment, patient again started deteriorating symptomatically. MRI showed increased bone marrow and soft tissue edema, Serum inflammatory marker CRP, ESR were elevated. Further investigations showed elevated Serum Fluoride (8.9mcmol/L) and Alkaline phosphatase (above 1,000 IU/L) level with positive Serum Galactomannan assay (2.3). This directed us to a possibility of voriconazole induced periostitis and patient was advised to stop antifungal treatment along with bed rest. Results: Four weeks follow up after discontinuing Voriconazole, showed reducing level of inflammatory marker (CRP- 9.9mg/L) with no mid back pain. And at 4 month follow up, MRI showed near complete resolution of soft tissue and bone marrow edema. Conclusion: Clinicians and spine surgeons should be aware of the fact that, long term Voriconazole treatment of invasive aspergillosis can be complicated by skeletal fluorosis and painful periostitis. Once the symptoms of periostitis develop, investigations such as skeletal imaging and measurement of serum fluoride levels should be performed and if periostitis deformans is confirmed reducing the dose or discontinuing voriconazole should be considered.

1833

P363: Bacterial Endocarditis as a Co-Existing Infection in Patients With Pyogenic Spondylodiscitis

Insa Janssen ¹ , Ann Kathrin Joerger ² , Melanie Barz ² , Jens Gempt ² , and Bernhard Meyer ²

¹ Hôpitaux universitaires Genève, Geneva, Switzerland

² Klinikum rechts der Isar, Neurochirurgie, Munich, Germany

Introduction: Pyogenic spondylodiscitis is often associated with a systemic co-infection, which can be both cause and consequence of the spinal inflammation. Particularly critical are patients suffering from concomitant endocarditis. Aim of the study was to assess the incidence, clinical course and treatment strategies of patients with pyogenic spondylodiscitis and associated bacterial endocarditis. Material and Methods: We performed a retrospective analysis of our clinical database. All patients suffering from spondylodiscitis between January 2018 and December 2019 were investigated. We assessed clinical findings, treatment and outcome of patients affected by both pyogenic spondylodiscitis and associated bacterial endocarditis. Results: Out of 143 patients suffering from pyogenic spondylodiscitis 10 patients were diagnosed with concomitant endocarditis. Six patients were female, four male. Mean age was 73.2 +\- 12.21 years (range 47-87). Localization of discitis was lumbar in six, multilevel in two and thoracic and cervical in one each case. Underlying germs were staphylococcus aureus (n = 5), staphylococcus epidermidis (n = 2), streptococcus sanguinis (n = 1) and streptococcus viridans (n = 1). In one case no germ could be isolated. Three patients died, whereas two patients died already after 2 and 4 days after hospitalization. The other patients all underwent neurosurgical treatment, cardiac surgery was only performed in 5. In two cases in two cases the perioperative risk was considered too high. Mean hospital stay was 37.7 +28.73 days with a mean stay at ICU for 9.8 +13.28 days. One patient suffered from complication due to septic cerebral embolism. In seven patients both the spine and the cardiac infection was healed. In two patients a relevant neurological deficit remained (tetraparesis n = 1; hemiparesis n = 1). Conclusion: Co-infection of pyogenic spondylodicitis and bacterial endocarditis most importantly affects the elderly with important comorbidities, especially concerning cardial predisposition, diabetes mellitus and immunodeficity. The mortality is high. Treatment strategy has to be discussed interdisciplinary in close collaboration with cardiologists and cardiac surgeons to choose the optimal type and order of treatment.

1840

P364: Surgical Treatment of Spondylodiscitis in the Elderly

Insa Janssen ¹ , Ann Kathrin Joerger ² , Jens Gempt ² , and Bernhard Meyer ²

¹ Hôpitaux universitaires Genève, Geneve, Switzerland

² Klinikum rechts der Isar, Munich, Germany

Introduction: Due to ageing society the incidence of pyogenic spondylodiscitis is still rising. Whereas surgical treatment for spodylodiscitis in general is more and more accepted as treatment of choice, there is not much known about the prognosis of spondylodiscitis in the elderly. Aim of the study was to assess the incidence, clinical course and outcome after surgical treatment of elderly patients. Material and Methods: We performed a retrospective analysis of our clinical database. All patients suffering from spondylodiscitis between January 2006 and January 2018 were included. We assessed clinical findings, laboratory tests, treatment and outcome comparing patients of an of 70 years or older with patients younger than 70 years. Results: In the defined period 454 patients were operated for pyogenic spondylodiscitis (male n = 289, female n = 165). We identified 213 patients aged 70 years or older (group 1) with a mean age of 76.78 +/- 5.56 years (range 70-94yrs). 241 patients were younger than 70 years (group 2) with a mean age of 58.35 +/- 10.44 years (range 17-69 yrs). Distribution of localization of discitis was similar in both groups. There was also no significant difference between the duration of hospitalization (group 1: 28.9 +/- 19.27 days; group 2: 24.83 days +/- 17.64 days). The majority of patients was cured, respectively 8 patients sustained a recurrence of infection. Conclusion: Surgical treatment of the elderly population suffering from spondylodiscitis is safe and not associated with a significantly worse outcome compared to the younger patient group.

1843

P365: Isolated Posterior Spinal Element Tuberculosis and Its Management: A Case Series of Twenty One Cases and Review of Literature

Sumit Kumar ¹ , Ravi Sreenivasan ¹ , Atul Sareen ¹ , Mohit Patralekh ¹ , Tankeshwar Boruah ¹ , and Ramesh Kumar ¹

¹ Vardhman Mahavir Medical College and Safdarjung Hospital, Spine Unit, Central Institute of Orthopaedics, New Delhi, India

Introduction: Spinal Tuberculosis (TB) is the most common form of extrapulmonary tuberculosis with an incidence rate of 1-3%. Tubercular spondylitis typically involves anterior elements, that is, vertebral body and intervertebral space. Isolated involvement of posterior element (neural arch) in tuberculosis is rare with reported incidence of less than 5% of total cases of spinal TB. Furthermore atypical presentation in these cases and occult changes on radiographs in early stages often leads to delayed or missed diagnosis. Surgical options routinely used in these cases are laminectomy with or without instrumentation and laminoplasty. A novel surgical technique, reposition laminoplasty was done in few of our cases. In reposition laminoplasty, cut lamina is repositioned back after achieving adequate decompression thus avoiding problems like spinal instability, scar formation and kyphotic deformity associated with laminectomy. Material and Methods: In this retrospective and follow-up study, data of 25 clinically, radiographically and histopathologically confirmed cases of isolated posterior element tuberculosis was taken from hospital database from 2015 to 2019 and patients with minimum one year of follow-up at the time of study were included. Patients with isolated intraspinal tubercular granuloma with no bony involvement were excluded from study. Patients’ chief complaints at presentation, level of vertebral involvement, part of vertebra involved, presence of posterior epidural abscess, neurology at the time of presentation and treatment given were noted. 4 patients were lost and 21 Patients were seen on follow up. On follow up, we looked for presence of any deformity and neurological status of the patient. Results: Out of 21 patients, 15 patients were male. Most common presenting complains were backache and weakness of both lower limb. There was involvement of cervical vertebra in 4 cases, thoracic vertebra in 14 cases and lumbar vertebra in 3 cases. Most common parts of vertebra involved were lamina and pedicle, in 16 and 12 cases respectively. Posterior epidural abscess was present in 14 patients. Grade IV paraplegia was seen in 9 patients. Six patients had grade II/III paraplegia whereas 6 patients had intact neurology. Patients with intact neurology were managed conservatively with Anti-tubercular therapy and these patients recovered fully on follow up. Laminectomy with or without instrumentation was done in 7 cases and reposition laminoplasty was performed in 8 patients. On follow up, none of these patients had kyphotic deformity and 9 patients recovered fully whereas in 6 patients, motor weakness was persistent. Conclusion: Atypical presentation of isolated posterior spinal element tuberculosis and lack of findings on radiographs in early stages often causes delay in diagnosis. A high level of suspicion is needed to avoid severe neurological deficits. Reposition laminoplasty is a novel technique that reduces risk of spinal instability and kyphotic deformity.

Keywords

tuberculosis, posterior spinal element, reposition laminoplasty

1860

P366: Spinal Implant-Associated Infections - What do we Know so far and What is Critical About it?

Daniel Karczewski ¹ , Klaus John Schnake ² , Ulrich Spiegl ³ , Bernhard Ullrich ⁴ , Scheyerer Max ⁵ , Osterhoff Georg ³ , and Pumberger Matthias ¹

¹ Charité University Medicine Berlin, Center for Musculoskeletal Surgery, Department of Orthopaedics, Berlin, Germany

² Malteser Waldkrankenhaus St. Marien, Center for Spinal and Scoliosis Surgery, Erlangen, Germany

³ University Clinic Leipzig, Clinic and Policlinic for Orthopaedics, Traumatology and Plastic Surgery, Leipzig, Germany

⁴ BG Clinic Bergmannstrost, Clinic for Trauma- and Reconstructive Surgery, Halle, Germany

⁵ Medical Faculty, University of Cologne, Department of Orthopedic and Trauma Surgery, Cologne, Germany

Introduction: Spinal implant-associated infections (SII) are an increasing challenge in the daily clinical routine, not only for orthopedic surgeons, neurosurgeons and microbiologists, but also for associated medical fields like general practitioners. This review intends to summarize existing knowledge in the field of SII, including its definitions, epidemiology, classifications, risk factors, pathogenesis, symptoms, diagnosis, and treatment concepts. Afterwards, the review identifies and discusses critical aspects of current concepts. Material and Methods: The search terms “spinal implant infection”, “perispinal implant infection” and “spinal infection” were used for a structured Pubmed, Cochrane Library, and Medline analysis. A total of 60 references were included at the end of the follow-up. Results: The review revealed structural problems in the field of SII, including (1) limited level of evidence in clinical studies (missing prospective controlled randomized studies, metanalyses), (2) small patient numbers, (3) missing standardized definitions (definition of the term “spinal implant infection”), (4) heterogeneity in patient groups (combined study groups including spinal infections with and without implants), and (5) redundancy in cited literature. Conclusion: Evidence-based knowledge about postoperative spinal implant-associated infections is lacking. Involved fields, including orthopedic surgeons, neurosurgeons, and microbiologists should come together to define the term PSII and to combine their approaches towards research, training, and patient care. This review proposes a possible definition of the term “spinal implant infection”, adapted on the basis of definitions for periprosthetic joint infections in arthroplasty.

1863

P367: A Rare Case of Aspergillus Nidulans Osteomyelitis - Case Report

Joana Tavares ¹ , Sara Casanova ² , Luís Marques ¹ , Ana Luís ¹ , and João Vaz ²

¹ Hospital Egas Moniz - CHLO, Neurosurgery, Lisbon, Portugal

² Hospital Egas Moniz - CHLO, Infectious Diseases, Lisbon, Portugal

Introduction: Aspergillus osteomyelitis is an uncommon and serious extra pulmonary manifestation of invasive Aspergillosis and is frequently associated with host predisposing conditions such as immunosuppression and long-term antibiotic use. According to a systematic review by Gentiel et al, only a minority of spondylodiscitis (0,5%) have fungal etiology, furthermore, in reviews carried out between 1965-2012 (Gamaletsou et al) and 1947-2013 (Wang et al) were identified only 3 and 4 cases of Aspergillus nidulans spondylodiscitis, respectively. Material and Methods: Given the rarity, we present this case report of a patient diagnosed with Aspergillus nidulans spondylodiscitis. Results: we report the case of a 56-year-old male patient with chronic HIV infection complicated by Burkitt lymphoma and gastric/esophageal candidiasis, and multiple infections treated with antibiotics. He was admitted to the emergency room with lumbar back pain radiating to both legs and paraparesis (muscle function level grade of 3) with 3-4 days of evolution. CT scan showed destruction of D12 and L1 vertebral bodies and an epidural mass with paravertebral extension, suggestive of an infectious process. Emergent surgical treatment was adopted with percutaneous bilateral pedicle screw fixation of D10-D11-L2 and L3, D12-L1 laminectomy and discectomy with the removal of a bulky disc with cicatricial tissue. Anatomopathological exam showed presence of hyphae and Fungal culture of the disc revealed growth of Aspergillus nidulans. Patient was started on voriconazole IV: 6mg/kg every 12h as loading dose, on the first day, followed by 4mg/kg twice daily. This was switched to oral formulation after 1 month of therapy. At discharge he was clinically better, his back pain improved and was capable of walking with a jewett vest and help of a third person. Imaging assessment after a month showed slight improvement and C-reactive protein normalized. Conclusions: Aspergillus osteomyelitis is a severe infection that if not aggressively treated can potentially be fatal (23% mortality). Aspergillus nidulans is frequently a contaminating species requiring a high level of suspicion to make the diagnosis. The diagnosis involves the microbiological diagnosis with fungus isolation in culture since there are no known specific imaging characteristics of this infection. Treatment includes antifungal therapy, being of special relevance the surgical debridement and appropriate spinal stabilization in most cases, given the low antifungal bioavailability on the bone.

1870

P368: Brucellosis With Lumbar Spine Involvement - Case Report

Tejasvi Agarwal ¹

¹ The Spine Foundation, Mumbai, India

Introduction: Brucellosis is caused by gram-negative, aerobic, non-motile, facultative, intracellular cocco-bacilli belonging to the genus Brucella. Brucellosis is spread from animals to humans by direct contact with infected tissue or by ingestion of milk or dairy products. In developed countries, human brucellosis is an occupation-related disease and occurs more commonly among farmers, veterinarians and laboratory workers. Osteo-articular involvement including spondylitis, sacro-iliitis, osteomyelitis, peripheral arthritis, bursitis and tenosynovitis is the most common complication of brucellosis affecting up to 85% of patients1. Hence patient with Fever and low backache whose differential diagnosis is being kept as infective etiology of spine clinically, Brucellosis should also be taken into consideration apart from Tuberculosis and Pyogenic. We present a rare case of Brucella-related lumbar spine involvement. Material and Methods: A 41 years old male who is a security guard by occupation came to hospital with chief complaints of Pain in the Lower back region radiating to Bilateral Lower limbs since 15 days followed by Fever with chills and rigor since 7 days. Patient presented with pain in low back region, which was sudden in onset severe in intensity, radiating to bilateral lower limbs, aggravates on forward bending, lifting heavy weight. Pain was so severe that patient was no able to walk. Pain was also associated with fever since 7 days, which was insidious in onset, High grade, associated with chills and rigor. There was evening rise of fever. There was no History of Trauma, Lifting heavy weight, Burning micturition, Weight loss, night cries and loss of appetite. Patient had no history of Tuberculosis. Patient had reported a significant history of close contact with cattle. Results: We first thought about Pott’s disease because the patient lives in endemic areas of tuberculosis. The Chest X-Ray also did not reveal any lesion. To confirm the diagnosis patient was taken up Percutaneous Trans-pedicular Biopsy from L5 vertebra. Sample was taken and sent for Gram stain, Culture and Anti-biotic sensitivity, ZN stain and Histo-pathological examination. G/S, C/S, ZN stain was normal and was inconclusive for diagnosis. Histopathology examination of a specimen revealed chronic inflammation without granulomatous inflammation. Since the patient had declared the history of close contact with cattle, our suspicion grew towards brucellosis with spine involvement. Brucella antibody titre was sent which came out to be positive with a strong titer of 77.1. Conclusion: A correct early diagnosis of brucellosis is important because it is an aggressive disease, which requires immediate treatment. Both medical history of the patient and results of laboratory tests should be evaluated with detailed clinical information for diagnosis of brucellosis. History such as close contact with cattle and consumption of un-pasteurized milk or dairy products are informative. Brucellosis with Spinal involvement is one of the most serious complications and the reported incidence varies from 2% to 60% out of with Lumbar Involvement is most common in spine. Hence Patient with such presentation should always be considered for evaluation for Brucellosis of spine to avoid wrong diagnosis and treatment.

1911

P369: Atypical Presentation of a Brucellian Spondylodiscitis: A Case Report

Mouadh Nefiss ¹ , Nouira Amine ¹ , Saied Abdellali ¹ , Bousrih Anis ¹ , Ezzaouia Khelil ¹ , and Tborbi Anis ¹

¹ Mongi Slim Hospital, Orthopedic Surgery Department, La Marsa, Tunisia

Introduction: The differential diagnosis of a vertebral lytic image in a young adult primarily includes benign and malignant tumor lesions and infections with a specific or non-specific germ. The diagnostic approach requires a good epidemiological analysis combined with clinical-biological and radiological assessment. We report the case of a difficult etiological diagnosis of a lytic image of the lumbar spine. Material and Methods: A 22 year old men, without any past medical history, who consulted for a low back pain evolving since 3 months without leg pain, weight loss, fever, night sweats or trauma. The radiological assessment showed an osteolytic image at the level of the upper plateau of the L5 vertebral body. Admission for further biological and radiological investigations has been decided. Results: Laboratory tests for inflammatory syndrome, infection with a specific or non-specific germ were negative except for a wright test within the limits of normality. MRI of the lumbar spine showed a sub-chondral intra-somatic geode at the upper plateau of L5 with no signs in of spondylodiscitis, tumor or chronic inflammatory process. For radiologists the diagnosis was pathognomonic of an intra-spongy hernia and that the scano-guided biopsy is not necessary. Therefore, this diagnosis was retained and the patient underwent functional and medical treatment. In front of the worsening of the low back pain the patient was readmitted. This evolution made us doubt the initial diagnosis especially with a worsening inflammatory pain. New investigations have been requested and the diagnosis of Brucellian spondylodiscitis was retained. The patient received antibiotics (oxycycline +rifampicin) with a good outcome. Conclusion: Brucellosis is an endemic disease in Tunisia. It must be mentioned when an osteolytic image is discovered, even when the clinical qnd radiological aspect is not very suggestive.

1930

P370: The Profile of Pott's Disease in a South American Reference Service

Igor de Barcellos Zanon ¹ , Robert Meves ¹ , Alberto Gotfryd ¹ , Nelson Astur ¹ , Rodrigo Góes Medéa de Mendonça ¹ , Maria Fernanda Caffaro ¹ , Mauro José Costa Salles ² , Giselle Burlamaqui Klautau ² , Taiana Cunha Ribeiro ² , and Vivian Tsai ²

¹ Santa Casa Spine Center - Group of Spine diseases at "Pavilhão Fernandinho Simonsen", Orthopedics and Traumatology at Hospital Santa Casa de Misericórdia de São Paulo, São Paulo, Brazil

² Infectology Group, Internal Medicine at Hospital Santa Casa de Misericórdia de São Paulo, São Paulo, Brazil

Introduction: Tuberculosis (TB) is a global public health problem with high morbidity and represents one of the top ten causes of death in the world. It predominates in underdeveloped countries and is related to poverty, malnutrition, immunosuppression and HIV infection. It is the main site of osteoarticular involvement of TB with about 50% of cases, and represents 1% of all cases. Insidious onset and nonspecific symptoms usually result in delayed diagnosis. The prognosis is directly related to early diagnosis and treatment institution. The aim of this study was to evaluate the characteristics of patients with Tuberculous Spondylodiscitis being followed up at a South American reference hospital. Material and Methods: Retrospective evaluation of medical record data, diagnosis of tuberculosis of the spine between 2009 and 2018, of both genders, between 0 and 80 years of age. The variables were analyzed based on groups: epidemiological, clinical, laboratory, microbiological, imaging tests and treatment. Results: Total of 26 cases, about 80.8% male, mean age 41.6 ± 22.46 years. Axial pain was the most prevalent symptom (84.6%), VAS was 6.85 ± 2.87. The mean time between symptom onset and diagnosis was 23.8 ± 24.1 weeks (4-96). The most affected region was the thoracic spine (50% of cases). The majority (61.4%) had neurological functioning (Frankel D and E) at the beginning of treatment and after 6 months, with 84.5% showing improvement. Treatment: 34.6% required surgery, and the main indication was isolated neurological deficit (55.5%). The most performed procedure was decompression and arthrodesis (55.5%). The average time to cure was 12.0 ± 8.8 months (8-48). Conclusion: The profile observed was that of a disease with insidious onset and nonspecific symptoms, a high frequency of negative microbiological tests in cases with the disease, less of the cases required surgical treatment and the majority showed good neurological recovery.

1954

P371: Tuberculosis of the Cervical Spine

Khalil Habboubi ¹ , Hassen Makhlouf ¹ , Guermazi Bassem ¹ , Ayachi Montassar ¹ , Lanouar Bouzid ¹ , and Mondher Mestiri ¹

¹ Kassab Institute, Tunis, Tunisia

Introduction: The spinal column is involved in less than 1% of all cases of tuberculosis (TB) [1.2]. Spinal TB (Pott’s disease) is a very dangerous type of skeletal TB as it can be associated with neurologic deficit due to compression of adjacent neural structures [3] and significant spinal deformity. Therefore, early diagnosis and management of spinal TB has special importance in preventing these serious complications. Although the development of more accurate imaging modalities and advanced surgical techniques, these are still very challenging topics. We report herein the case of a woman who had cervical spinal TB, treated medically with good result. Case report: A 59-year-old woman presented to our emergency department with a 9-week history of worsening neck stiffness. She reported no recent history of trauma and denied previous TB exposure. Systemically, there was no loss of appetite, weight loss or sweats or fever. Herneck was stiff. Neurological examination revealed no focal motor weakness. Reflexes were present and symmetrical and sensation to light touch was normal. Base-line blood investigations were normal. A chest radiograph demonstrated no anomaly. A lateral cervical spine radiograph demonstrated osteolytic lesion of the body of C3 with a retrolisthesis C2/C3 and soft tissue density in the pre-vertebral and retropharyngeal soft tissues (Figure 1). Sputum was sent for acid-fast bacilli (later noted to be negative). An MRI of the cervical spine demonstrated altered signal intensity within the C2–C4 vertebral bodies with a fragmentation of the body of C3 with an extension to the pre-vertebral soft tissues and the anterior epidural space (Figure 2). There was no evidence of enhancement within the cord. The lesion resembled neoplasm metastasis. Thoracic CT scan revealed osteolytic lesion of the third and ninth left ribs. Abdominal and cervical ultrasonographies were normal. A Ct scan guided biopsy of the spine lesion was done and the neuropathological examination of the biopsy showed typical granulomatous inflammation with characteristic infiltrate of lymphocytes, epithelioid macrophages and Langhans-type multi nucleated giant cells. A diagnosis of tuberculosis was made and the patient initiated quadruple antitubercular therapy (Rifampicin 450 mg o.d., Isoniazid 300 mg o.d., pyrazinamide 1.5 g o.d. and ethambutol 600 mg o.d.) and the application of a minerva with front cover for 12 months. The patient made an uneventful recovery. Radiographic healing with formation of a callus was seen at six months. At 12 months complete fusion between the vertebral body of C3 and C4 was observed despite a residual C1-C2 instability (fig3). The patient returned to active social life within 3 months of having initiated treatment and completed the full 12 month course of antituberculosis drugs. Conclusion: The prognosis for spinal tuberculosis is improved by early diagnosis and rapid intervention. A high degree of clinical suspicion is required if patients present with chronic neck pain, even in the absence of neurological symptoms and signs. Medical treatment is generally effective. Surgical intervention is necessary in advanced cases with marked bony involvement, abscess formation, or paraplegia.

1967

P372: Bacterial Propagation Through Surgical Sutures: A Potential Modifiable Risk Factor Against Surgical Site Infection

Hassan Fawi ¹ , Panagiotis Papastergiou ² , Andrew Hart ³ , and Nigel Coleman ¹

¹ Queen Elizabeth Hospital, Trauma and Orthopaedics Department, Kings Lynn, United Kingdom

² Limassol General Hospital / Norfolk and Norwich Hospital, Microbiology Department, Limassol, Cyprus

³ Norfolk and Norwich Hospital, Microbiology department, Norwich, United Kingdom

Aims: We investigated whether bacteria can propagate through multifilament, monofilament sutures and whether the sutures coated with triclosan would exhibit a different phenomenon. Materials & Methods: One cm wide trench was cut in the middle of a Columbia blood Agar. We tested a 6cm length of each type of suture: PDS size 1, PDS-Plus 1, Vicryl 2.0, and Vicryl-Plus 2.0. Each suture was inoculated with a bacterial suspension containing methicillin-sensitive Staphylococcus aureus (MSSA), Escherichia coli (E. coli), Staphylococcus epidermidis, methicillin-resistant Staphylococcus aureus (MRSA) to one end of each suture. The plates were incubated at 36°C for 48hours, following which, were kept at room temperature for further 5days. We observed for any bacterial growth on the other side of the trench to establish any bacterial propagation. Results: Bacterial propagation was observed on the other side of the trench with both suture types, monofilament PDS and multifilament Vicryl, when we tested the motile bacteria, E. coli. Propagation was not observed on the other side of the trench with the monofilament PDS suture following incubation with MSSA, S. epidermidis and in 66% of MRSA. Whilst propagation was observed on the other side of the trench in vast majority with multifilament suture vicryl following incubation with same organisms. No bacterial propagation was observed in any of the triclosan coated sutures for 7 days. Conclusions: Monofilament sutures are associated in-vitro with less chance of bacterial propagation along its course in comparison to multifilament. Inhibition of bacterial propagation was further enhanced when triclosan-coated monofilament sutures were used.

Medical Economics

265

P373: Cost utility Analysis of Microdiscectomy Versus Non-Operative Management for the Treatment of Chronic Radiculopathy Secondary to Lumbar Disc Herniation

Andrew Glennie ¹ , Jennifer Urquhart ² , Prosper Koto ³ , Parham Rasoulinejad ² , David Taylor ² , Keith Sequeira ⁴ , Tom Miller ⁴ , Jim Watson ² , Richard Rosedale ² , Stewart Bailey ² , Kevin Gurr ² , Fawaz Siddiqi ² , and Chris Bailey ²

¹ Dalhousie University, Halifax, Canada

² London Health Sciences Center, London, Canada

³ Nova Scotia Health Authority, Halifax, Canada

⁴ St. Jospeh's Healthcare, London, Canada

Introduction: A recent randomized control trial comparing early surgery to 6 months of conservative care was performed for chronic sciatica of 4-12 months duration. The purpose of the current study is to evaluate the cost-effectiveness when comparing both strategies of care. Material and Methods: A decision tree model was created and parameterized using data from a single-center, randomized control trial design, augmented with institutional cost data. Quality-adjusted life-years (QALYs) derived from EQ-5D-3L was the health outcome. The cost-utility analysis was from the payer perspective. Cost-effectiveness was assessed using the incremental cost-utility ratio (ICUR), and a threshold of willingness to pay (WTP) of CAD 50,000/QALY in the base case. Sensitivity analysis was performed both with probabilistic sensitivity analysis (PSA) and two one-way sensitivity analyses. Results: One hundred twenty-eight patients were included in the study, accounting for potential outcomes and cross-over rates between treatment groups. Patients in the surgical group had relatively higher expected costs but had better expected health outcomes. The ICUR was CAD 6,683/QALY gained (95% CI: 730 – 29,893). Probabilistic sensitivity analysis demonstrated that the likelihood that early surgical treatment is cost-effective was 0.99 at the WTP threshold. Conclusion: Early surgery is cost-effective when compared with non-surgical care. Decision makers should ensure access to timely surgical care, especially in single-payer systems.

280

P374: Barriers of Neurophysiology Monitoring in Spine Surgery: Latin America Experience

Alfredo Guiroy ¹ , Marcelo Alejandro Valacco ² , Martin Gagliardi ¹ , Gaston Camino Willhuber ³ , Juan Pablo Cabrera Cousio ⁴ , Asdrubal Falavigna ⁵ , and Juan Emmerich ⁶

¹ Spanish Hospital, Orthopedics, Mendoza, Argentina

² Hospital Churruca, Buenos Aires, Argentina

³ Hospital Italiano, Orthopedics, Buenos Aires, Argentina

⁴ Hospital Clinico de Concepcion, Concepcion, Chile

⁵ Caxias do Sul University, Neurosurgery, Caxias do Sul, Brazil

⁶ Hospital Español, Neurosurgery, La Plata, Argentina

Introduction: Intraoperative neurophysiological monitoring (IONM) has become standard of care during spine surgery. However, it is not always available in many spine centers, especially in developing countries. The objective of this paper is to evaluate the use, access and limitations of IONM in spine surgeries in Latin America. Material and Method: We developed a questionnaire that included demographics of Latin America spine surgeons and their opinion about the utility of IONM in different scenarios. Main variables were: nationality, years of practice, specialty (ortho or neuro), level of the hospital, number of surgeries perform annually, pathologies more frequently operated and the importance given to IONM in some particular pathologies. Results were analized and compared between specialties, level of experience and countries. Results: 200 AO Spine Latin America surgeons from different countries answered the survey. The sample was mostly from orthopedic surgeons (62%) and surgeons in practice for more than 10 years (54%). Mostly of the surveyed perform more than 50 surgeries a year (69%), predominantly degenerative cases (76%). The most cited limitation for access to IONM was economic (57%). For adolescent idiopathic scoliosis, thoracolumbar kyphosis correction and intramedullary tumors surgeons consider more frequently that IONM was indispensable. 64% of the surgeons changed their preoperative plan at least once in response to some variation of intraoperative neurophysiology. Conclusion: This is the first study assessing use, accessibility and limitations of IOM in Latin America. The main limitation of its use in this Region is economical. Remarkably, some spine surgeons did not consider to IOM an indispensable tool for many complex surgeries.

306

P375: 'Are we Our Own Patients?' Neck Pain in Spine Surgeons: Prevalence and Risk Factors

Hriday Acharya ¹ , Munjal Shah ¹ , Harshal Bamb ¹ , Priyank Patel ¹ , and Abhay Nene ¹

¹ Lilavati Hospital and Research Center, Mumbai, India

Introduction: The prevalence of neck pain has been reported in various medical sub-specialities including laparoscopy surgeons, dentists, plastic surgeons, ophthalmologist, urologist and orthopaedic surgeons. However, the literature is lacking on prevalence and risk factors for neck pain in spine surgeons. This survey amongst spine surgeons aimed to determine the prevalence of neck pain and identify the associated risk factors. Material and Methods: A survey questionnaire containing demographic, neck pain, and work practice details was administered to 300 members of an online spine surgeons group via text message and e-mail. One hundred and eighty surgeons responded to the survey (response rate, 60%). Three spine surgeons were excluded due to previous cervical spine surgeries and data from 177 respondents were analysed. Results: The 1-month prevalence rate of neck pain was 74% (131/177 surgeons). One hundred and seventeen surgeons (89.5%) reported only neck pain, 14 surgeons (10.5%) had neck pain with radicular arm pain. Only 20.5% of surgeons used a loupe, 18% of surgeons used a microscope, and 24% of surgeons used optimum operating table height during surgery. There was no significant difference between the mean age (P = .88), work experience (P = .44), time spent in surgery (P = .08), use of visualisation tools (P = 1.00), and operating table height preference (P = .71) when symptomatic and asymptomatic groups were compared. However, a significantly greater percentage of surgeons had a sedentary lifestyle (P = .009). There was significant correlation between the surgeon’s lifestyle and the incidence of neck pain. When comparing using loupes and microscope, in surgeons using magnification; surgeons with loupe were at a risk. Conclusion: Spine surgeons in a limited-resource setting have a higher prevalence of neck pain than general populations and surgeons from other specialties. Considering the high prevalence of neck pain, general health, work, and ergonomic guidelines and recommendations must be formulated to help prevent and decrease the burden of neck pain among spine surgeons.

503

P376: A 2-Year Retrospective Study of Data From a Regional Spine Centre to Evaluate Staff and Patients Compliance Regarding Data Entry to the British Spinal Registry

Emily Tsang ¹ , Cristina Lupu ¹ , Angelo Fragkakis ¹ , Jason Bernard ¹ , Timothy Bishop ¹ , and Darren Lui ¹

¹ St George's University Hospital NHS Trust, London, United Kingdom

Introduction: The British Spinal Registry (BSR) is a web-based database commissioned by the British Association of Spine Surgeons (BASS) in the UK. It allows auditing of spinal surgery outcomes, patient’s safety and overall experience. The clinical data include patient’s demographics which is entered into the Registry by medical staff, as well as patient-reported outcome measures (PROM) that is submitted to the Registry by the patient themselves at different time periods post-operatively. It has the ability to register Device and Implants as well as co-ordinate multicentre research. This study is to identify both the staff and patient compliance regarding to data submissions to the BSR at St. George’s Hospital NHS Trust. Methods and Materials: Retrospective analysis of the BSR data for all spinal surgeries that was performed at SGH by the three Complex Spinal Surgery Consultants between 1st January 2017 to 31st December 2018. This study period allowed up to 12 months PROM data analysis. Staff and Patient compliance were analysed separately depend on the data they submitted. Results: 404 (n) spinal surgeries were performed over this two-year period. Surgical demographics: 39.4% (159/404) males and 56.2% (227/404) females, 4.5% (18/404) declined to be added. Age ranging from 6 to 92, mean age was 47.9. Staff compliance was 89.4% for the registration of patient data. Trauma and tumour patients were excluded as they are not required to complete any pre-operative PROMs. For the remaining patients, 35.8% (116/324) completed their baseline pre-operative PROMs. A steady decrease in patient compliance for post-operative PROMS was observed: 29.8% (2 weeks), 24.9% (6 weeks), 21.2% (6 months), 17.1% (12 months), and16.6% (24 months). Conclusions: We identified a poor patient compliance in both pre-operative and post-operative PROMS. Patient questionnaire fatigue can occur over time which results in falling compliance to PROMS in 12 months and 24 months. Moreover, patients who do not provide an email address are less likely to fill in their PROMS. Satisfactory compliance for staff regarding to BSR utilisation are shown. Staff should aim to achieve a higher level of compliance as this will help to keep a record of all spinal surgeries that are performed and any complications that are encountered in a particular centre. Over the past three years, the BSR had introduced various schemes to drive up utilisation including a Best Practice Tariff in 2019. Part of the tariff will be withheld when staff failure to enter patients onto the Registry. Further research is needed to determine why there is such fall off especially with patient compliance and to elucidate potential measures to improve their compliance.

626

P377: Strategic Action for Cost-Effective Management of a Waiting List: Results of Specialized Evaluation of Surgical Options in a Prospective Cohort Referred for Spinal Surgery

Juan Lourido ¹

¹ Servicio Canario De Salud, Santa Cruz De Tenerife, Spain

Introduction: Spinal disorders are the leading cause of disability (YLD) in most countries. Surgery indications are increasing and with a growing population and increase of prevalence and incidence, it has become a condition with a progressive major socioeconomic impact. Only increasing the resources has not been proven a solution and better management strategies are sought. Waiting lists are a major problem in the world in countries with a public health system, but the size of the waiting list might not reflect the real needs of surgery in the population. Material and Methods: In cooperation with the Health Provider, an experienced spinal surgeon (more than 1000 operations performed, all spine levels) was assigned to review all patients referred for spinal surgery consideration from Primary and Secondary Care Centers in a geographically restraint area with only one Tertiary Center of reference. These patients represent the incidence, because of a large outpatient waiting list in the Tertiary Center. Emergency cases are excluded as the Healthcare System does not allow such cases to be included in waiting lists. The reviewer could not have the possibility of handling or being involved in any way in the future treatment of the patient. Evaluation was performed in a Primary Care Center, patients were allocated with 15 min interval, and clinical and imaging studies were evaluated. All patients presented with at least one MRI study, which was considered valid if no clinical changes had taken place since the moment of the study. Otherwise, a new MRI was indicated. Patients were routed either for physiotherapy, pain therapy unit, or surgery. Surgical indication was stablished as urgent (to be operated in one month), priority (three months) or normal (to be included in regular waiting list), based on clinical signs, progression of symptoms or deficits, and impairment of work or quality of life. Evaluations were performed an average of once a month in the period December´17 to July´19 (20 months). Results: 718 appointments, 51 no-shows (7%) and 20 rescheduled (3%) 651 patients evaluated, 626 as a first visit (96%) and 25 needing a second visit (4%) 544 patients (84%) referred to conservative treatment, 29 (4%) new studies were ordered 78 patients were confirmed for surgery (12%): 11 patients were marked as “urgent” (2%), 23 patients “priority” (3%), 46 patients as “normal” (7%). No patient from the non-surgical group requested reevaluation to be included for surgery during this period. (Local demographics to be presented). Conclusion: Our data provide reliable feedback to assist the local Healthcare Management to allocate resources, and provide insights that can be extrapolated to other populations. Ad-hoc personalized evaluation by a specialist is feasible and efficient in the Primary Care setting. Factoring the amount of available surgical resources for our population, this data show that the size of the local surgical waiting list does not reflect the need for surgery by the population.

812

P378: Estimation of a USA Population Utility Value set for the Eight-Item Spine Oncology Study Group Outcomes Questionnaire

Markian Pahuta ¹ , Felicity Fisk ¹ , Anne L. Versteeg ² , Charles Fisher ³ , and Nicolas Dea ³

¹ Henry Ford Health System, Detroit, USA

² Utrecht University, Utrecht, The Netherlands

³ University of British Columbia, Vancouver, Canada

Introduction: Treatment decision making for metastatic spine disease is challenging since multiple patient and treatment related factors including patient performance status, survival prognosis and risk of adverse events must be considered. QALY analysis could help patients and clinicians jointly assess the trade-offs between survival, health-related quality-of-life (HRQoL) benefits, recovery, and potential complications to reach an optimal treatment decision. QALYs are also required in economic analysis because economic decisions are based on the incremental cost-effectiveness ratio, which is the cost per QALY gained. QALYs are calculated using utilities, or HRQoL weights. The AOSpine Knowledge Forum Tumor (former Spine Oncology Study Group, SOSG) developed an eight-item spine oncology‐specific outcome questionnaire (SOSGOQ-8D) which is suitable for developing a utility mapping. The primary objective of this study is to develop a utility mapping for the SOSGOQ-8D for the USA general population perspective. The secondary objective of this study is to determine the relative importance of various aspects to quality-of-life in metastatic spine disease. Material and Methods: We recruited a sample of 3821 adults from a market research company. Quota sampling was used to ensure that the participants were representative of the USA population in terms of age, gender, and state of residence. Participants were asked to rate 10 of 100 S-optimal SOSGOQ-8D health states in a discrete choice experiment. Utility mapping was developed using a random-effects conditional logit regression model. Results: Of 3821 individuals recruited, 749 (20%) met all quality criteria. Response quality was not related to perceived difficulty of the DCE task. Regression parameter estimates were monotonic for each domain which indicated sensible and valid results. Self-care and social function items were the greatest determinants of health state utility.Conclusion: We have provided utility estimates for the SOSGOQ-8D. The utility values derived from this study can be used to help inform population-level healthcare decision making, such as allocation of limited resources for specific treatments. The ability to calculate QALYs for metastatic spine disease will enhance treatment decision making and facilitate economic analysis. When offering treatment, clinicians should be mindful that extremity neurologic function is not the greatest determinant of utility, and thus HRQoL.

1231

P379: Reduced Hospitalization Cost of Transforaminal Lumbar Interbody Fusion Due to the use of a New Device

John Peloza ¹ , Michael Millgram ² , Nahshon Rand ² , Richard Guyer ³ , Jean Charles Le Huec ⁴ , and Ely Ashkenazi ²

¹ Center For Spine Care, Dallas, TX, USA

² Assuta Medical Center, Israel Spine Center, Tel Aviv, Israel

³ Texas Back Institute, Plano, TX, USA, ⁴ Bordeaux University School of Medicine, Bordeaux, France

Introduction: Transforaminal Lumbar Interbody Fusion (TLIF) procedures are commonly performed and pose a significant financial burden on patients, hospitals and insurers. Clinical outcome is tightly linked with procedure cost, as complications and readmissions can be costly and decrease or diminish the overall profit. Reducing procedure cost, while maintaining efficacy, may be assisted by a new powered device, designed to clean the end plates for improved cartilage removal and shorten the time required for disc removal. The aim of the study was to assess the changes in clinical, operative and economical parameters in TLIF procedures due to the use of the device in a single hospital. Material and Methods: The records of 208 single-level TLIF procedures were reviewed in order to calculate changes in procedure outcome, hospitalization parameters and overall cost. 143 procedures were conducted using the new device and 65 procedures were conducted using traditional tools and methods and were used as a control group. The cost per unit of different components affecting the overall cost was derived from the literature, online resources and the hospital's financial department, and used to estimate the overall cost changes. Results: The analysis revealed a statistically significant reduction in surgery duration (23 minutes, after controlling for procedure year and patient characteristics, P < .001). Reductions in length-of-stay (0.44 days, P = .5), complication rate (-55%, P = .21) and readmission rate (-32%, P = .67) due to the use of the device were also noted. Overall, the improvements led to a statistically significant cost reduction of approximately $2,000 (P < .01), which is considerably higher than the device’s listed price. Conclusion: The study suggests that the device use can lead to a cost reduction and shorter procedure and hospitalization without deteriorating the clinical outcome.

1435

P380: Neck and Back Pain Emergency Department Visits at a Community Hospital: Reduction of Repeat ED Visits by Collaboration With an Evidenced Based and Multidisciplinary Outpatient Spine Program

David BenEliyahu ¹ , Adam Wos ² , Sumeer Sathi ^{1, 3} , Katlyn Conville ¹ , and Alan Kaell ^{4, 5}

¹ Mather Hospital, Back and Neck Pain Center, Port Jefferson, USA

² Mather Hospital, Emergency Dept, Port Jefferson, USA

³ Mather Hospital, Chairman, Dept. Of Neurosurgery, Port Jefferson, USA

⁴ Mather Hospital, Residency Program, Port Jefferson, USA

⁵ Zucker School of Medicine Hofstra/Northwell, Adjunct Clinical Professor of Medicine, Hempstead, USA

Introduction: Acute or chronic neck/back pain (NBP) accounts for 3% of annual nationwide Emergency Department (ED) visits, many of which are repeat visits from the same patient. This can result in both repeated diagnostic tests and increased expenditures. Health care expenditures in the ED continue to rise at a rapid pace with an increase of over 176% in the last decade. Managing patients with back and neck pain more efficiently through population health management principles and evidenced based practice, could significantly reduce costs and enhance clinical outcomes. As healthcare systems shift to an emphasis on clinical and value-based outcomes, reducing unnecessary ED admissions for patients with chronic recurrent NBP is much needed. To reduce repeat visits, we implemented a performance improvement project (PIP) with collaboration between our ED and our comprehensive outpatient spine program (OSP). The hospitals OSP model incorporates integrative, psychosocial, and population health principles that focuses on management of spine risk factors. The purpose of the PIP project was to quantify whether collaborating with the OSP resulted in a reduction in NBP visits to the ED over the 4 years, particularly in patients who had 2 or more visits prior to their OSP participation. Materials and Methods: Our patient sample included 156,531 encounters to our ED that occurred over a 4-year period from 2016-2019. 11,969 encounters (7.6%) were for patients with NBP complaints. 3411 of the 11969 (28%) encounters for patients with NBP over the 4-year period had ≥2 visits and represented 2.14% of all ED encounters (Group 1). Of those, 37 patients made ≥2 visits to the OSP (Group 2). Results: Overall 26/37 (70 %) of group 2 patients had long term positive improvement.

o 10/37 (27%) with 2 prior ED visits had none after attending the OSP.

o 13/37 (35%) each made 3-4 visits to the ED prior to being seen at the OSP and then made only 1-2 more visits to the ED afterwards.

o 3/37 – (10%) visited once and were sent back to the ED the same day for urgent diagnostic testing & management. They had no additional ED visits.

Conclusion: The percentage of our ED visits per year attributed to NBP disorders is 7.6%, more than twice the reported USA national average. Our number of patients seen twice or more for NBP complaints is over 2% per year. Of the frequent ED visits by NBP patients who did attend our OSP, 70% either did not visit the ED again, or had reduced future ED visits. Limitations of our PIP descriptive and exploratory analysis will be described. We anticipate improving the capture of additional NBP patients with 2 or more visits to the ED for referral to our PIP program by incorporating OSP referral information into discharge papers as well as after care follow up calls. Close collaboration between a hospitals ED and OSP can reduce repeat ED admissions for frequent repeat visitors by treating the pain generators, and managing associated risk factors, which enhances both clinical and value based outcomes.

1633

P381: Postoperative Medical Optimization After Spine and Total Joint Arthroplasty Surgery Decreases Readmission Rate

Hossein Elgafy ¹ , Megan Mooney ¹ , Emily Wyankoop ¹ , Anthony Kouri ¹ , Mina Tanios ¹ , and Daniel Gehling ¹

¹ University of Toledo , Orthopedic, Toledo, United States

Introduction: Over the past decade, new health care reforms, due to the Patient Protection and Affordable Care Act, have introduced all-cause hospital readmission as a determinate metric for quality of care. Concurrently, payers have started to implement bundled payment systems, in which hospitals will be accountable for the costs of readmissions for any reason, up to 90 days from discharge. Therefore, decreasing the readmission rate will allow for cost savings. The aim of the current study was to assess factors associated with 30-90 day readmission after spine and total joint replacement surgeries. Materials and Methods: We compiled a randomized list of 999 spine and total joint patients who underwent surgery at our institution between 2014-2015. From this, we compiled a database with information regarding the length of stay, number of consults, 30- and 90-day readmission, medical comorbidities, and patient demographics. Pearson correlation coefficients were calculated between the variables of interest. Results: A 90-day re-admission correlation coefficient of -.13 was observed when compared to the number of consults obtained after surgery (P < .05). Additionally, a -.11 correlation coefficient was observed when correlated with length of stay (P < .05). A 30-day re-admission correlation coefficient of -.09 was observed when correlated with number of consults (P < .05). A -.07 correlation coefficient was observed when correlating 30-day re-admission and length of stay (P < .05). Conclusion: Our results indicate that those patients who are optimized medically for discharge, following spine or total joint surgery, have a significantly lower likelihood of readmission at 30 and 90 days. Furthermore, our results demonstrate that patients with longer lengths of stay necessary, for medical optimization, will lead to a lower likelihood of readmission. Based on the findings of the current study, the authors recommend, medically optimizing patients prior to discharge to decrease readmission and the associated penalties. This may require more consults and longer length of hospital stay.

1887

P382: Covid 19 Pandemic: Update on the Reaction Attitude of the Spine Societies and their Members

Alessandro Ramieri ¹ , Omar Elhamy ¹ , Massimo Miscusi ¹ , Sokol Trungu ² , Antonino Raco ¹ , and Giuseppe Costanzo ¹

¹ Sapienza University, Rome, Italy

² Cardinal G. Panico, Tricase, Italy

Introduction: During the second phase of COVID-19 pandemic, some authors have felt the need to summarize and order data on the recommendations issued by the major neurosurgical scientific societies in the world. The concluding observations of this review highlighted how the neurosurgical scientific community had promptly reacted to the emergency by issuing documents and guidelines. Similarly, we designed a comprehensive review of the literature in relation to the release of documents, guidelines, or recommendations by the multiple spine societies in the world. Material and Methods: A review of the MEDLINE database (PubMed - National Library of Medicine), Google and Google scholar was performed on Monday, March 2, 2020 to date, for articles published in the English language. Search terms included: COVID-19, coronavirus, pandemic, spine, surgery, spine societies, guidelines, recommendations. We reviewed search results to assess the relevance of documents on these topics, including editorials, letters, webpages. References were reviewed to locate other articles of interest. We divided societies, associations or networks wordwide in 3 distinct groups: Continental (C), Speciality (Sb) or Country based (Cb) societies. Results: We were able to identify 26 associations, present on the web as companies or networks that deal with the interventional treatment of spinal pathologies. There were 8 major continental companies, but only a third had issued guidelines in the form of scientific work in a journal or document. The NASS guidance, released on April 22, is probably the most cited document in subsequent scientific papers. The Sb societies seem not to have addressed the topic. Only the SIS has a web document with its guidance. The AO spine website shows some corporate strategies for maintaining internal research and training or webminars and surveys. The greatest interest was paradoxically from regional scientific societies (Cb), with publications in journals, web or editorial documents. Conclusion: Only a third of continental spine societies have issued recommendations, although those of NASS are generally the most followed. The international specialist companies have dealt little or nothing with the topic, with the exception of the SIS and part of the AO spine. Paradoxically, the national companies were found to be more stimulated to issue their own guidelines. The local epidemiological severity has probably influenced the reactive corporate attitude. However, some companies are lacked.

1904

P383: Understanding Differences Between Spine Resident Training Programs and Evaluation of the Surgical Skills Among Residents Worldwide

Franziska Anna Schmidt ¹ , Ghidinelli Monica ² , Wong Taylor ³ , Julia Landscheidt ⁴ , and Sertac Kirnaz ³

¹ Medical University Innsbruck, Neurosurgery, Innsbruck, Austria

² AO Foundation, Zürich, Switzerland

³ Weill Cornell Medicine, New York City, USA

⁴ Klinikum Bogenhausen, Munich, Germany

Introduction: Spine surgical training and skills are not homogeneous within regions worldwide, this can lead to different patient outcomes. In many countries, duty-hour restrictions have been implemented within the last decade making it challenging to provide education and surgical training regularly in a hospital. The [fx4][fx18]primary aim of this study is to determine the current status of orthopedic/neurosurgery residency training programs in regard to spine surgeries, operating room (OR) exposure, and the number of procedures performed. The study will also reveal the main differences among the neurosurgical and orthopedic residency programs in terms of program directors, mentoring, educational courses, and training experience. A secondary aim is to evaluate the residents’ satisfaction, workload, and working environment. Material and Methods: An online questionnaire has been sent to orthopedic and neurosurgical residents in each region (Europe, Asia, Australia, Africa, South America, North America). The goal is to receive a minimum of 4 completed responses from each level of education in each region. Considering an average education time of 6 years, we aim to receive at least 144 surveys. Results: Quantitative and qualitative data will be analyzed to identify similarities and differences across regions. Conclusions: This analysis of the current status in spine surgery training can be used to design an international curriculum to improve standard of care for patients. In addition, we can identify areas that are in need of improvement in resident working conditions. Analysis of the differences among regions in spine resident training programs will allow to identify best practice and elements that could be improved.

Minimally Invasive Spine Surgery

29

P384: Minimally-Invasive Lumbopelvic Stabilization Of Sacral Fragility Fractures in Immobilized Geriatric Patients: Feasibility and Early Return to Mobility

Peter Obid ¹ , Andreas Conta ² , Philipp Drees ³ , Thomas Niemeyer ¹ , and Norbert Schütz ⁴

¹ Asklepios Paulinen Klinik, Spine and Scoliosis Senter, Wiesbaden, Germany

² University of Mainz, Mainz, Germany

³ University of Mainz, Department of Orthopaedics and Traumatology, Mainz, Germany

⁴ Asklepios Paulinen Klinik, Department of Geriatric Medicine, Wiesbaden, Germany

Introduction: In an aging society the incidence of sacral fragility fractures is increasing and diagnosis is often delayed. Immobilization has devastating consequences especially in elderly patients. Short-term mobilization of these patients is crucial. The aim of this study is to evaluate the early return to mobility of immobilized geriatric patients with sacral fragility fractures treated with minimally-invasive lumbopelvic stabilization. Material and Methods: Retrospective analysis of thirteen consecutive patients (13 females) which could not be mobilized with conservative treatment and were treated with minimally-invasive lumbopelvic stabilization. Pain intensity measurement on an 11-point Numeric Rating Scale (NRS), Tinetti Mobility Test (TMT), and Timed Up and Go Test (TUGT) were performed preoperatively and four weeks postoperatively. Surgical and medical complications were analyzed. Results: Mean age at surgery was 83.92 ± 6.27 years and mean ASA score was 2.77 ± .42. NRS improved from a mean of 7.18 ± .98 preoperatively to a mean of 2.45 ± 0.93 four weeks postoperatively (P < .001). TMT score improved from a mean of 4.15 ± 3.67 preoperatively to a mean of 16.39 ± 4.61 four weeks postoperatively (P < .001). Due to immobilization patients were not able to finish TUGT preoperatively. Four weeks postoperatively TUGT reached a mean of 31.1 ± 11.08 seconds. There were two surgical complications (one wound healing disorder, one rod dislocation) in two patients that required revision surgery. Two patients developed pneumonia postoperatively. Conclusion: Minimally-invasive lumbopelvic stabilization of sacral fragility fractures is safe and feasible in geriatric patients. It is effective in terms of early mobilization and early return to mobility. The rate of complications is acceptable.

50

P385: What is the Comparison in Robot Complications, Radiation Exposure, and Clinical Outcomes Between Percutaneous and Open Robot-Assisted Short Lumbar Fusion? A Multicenter, Propensity-Matched Analysis of 310 Patients

Nathan Lee ¹ , Ian Buchanan ¹ , Venkat Boddapati ¹ , Justin Mathew ¹ , Paul Park ¹ , Eric Leung ¹ , Avery Buchholz ² , John Pollina ³ , Ehsan Jazini ⁴ , Colin Haines ⁴ , Thomas Schuler ⁴ , Christopher Gooed ⁴ , Joseph Lombardi ¹ , and Ronald A. Lehman ¹

¹ The Och Spine Hospital at New York-Presbyterian, New York, USA

² University of Virginia Health System, Neurosurgery, Charlottesville, USA

³ State University of New York, Neurosurgery, Buffalo, USA

⁴ Virginia Spine Institute, Orthopedics, Reston, USA

Introduction: There is conflicting literature on the superiority of minimally invasive robotic spine surgery in comparison to conventional open techniques. A large, multicenter study is needed to further elucidate the outcomes and complications between these two approaches. Material and Methods: We included adult (≥18 years old) patients who underwent robot-assisted short lumbar fusion (1- and 2-level) surgery from 2015 to 2019. A propensity score matching algorithm was employed to control for the potential selection bias between percutaneous and open surgery. Outcomes of interest included operative efficiency (robot time per screw), radiation exposure (fluoroscopy time per screw), robot complications (e.g. screw exchange, robot abandonment), and clinical outcomes (e.g. length of stay, 90-day reoperations). The minimum follow-up was 90 days after the index surgery. Chi-square/fisher exact test and t-test/ANOVA were used for categorical and continuous variables, respectively. Results: After propensity score matching, a total of 310 patients were included in this study. The mean (standard deviation) charlson comorbidity index was 1.6 (1.5) and 53% of patients were female. The most common diagnoses included high grade spondylolisthesis (48%), degenerative disc disease (22%), and spinal stenosis (25%), and the mean number of instrumented levels was 1.5 (0.5). The mean operative time was significantly longer in the open group (198 minutes) vs the percutaneous group (167 minutes, P-value = .007). The mean robot time per screw was similar between cohorts. However, the mean fluoroscopy time per screw for percutaneous surgery (14.4 seconds) was significantly longer than the open group (10.1 seconds, P-value = .021). Robot complications, including screw exchange and robot abandonment, was similar between groups. The estimated blood loss (open: 146 mL vs percutaneous: 61.3, P-value < .001) and perioperative blood transfusion rate (open: 3.9% vs percutaneous: 0%, P-value = .013) were significantly greater for the open group vs the percutaneous group. The 90 day postoperative surgical complication rates and mean length of stay were not significantly different between cohorts. Conclusion: For short lumbar fusion, percutaneous robot-assisted spine surgery can achieve a shorter operative time and lower risk for intraoperative blood loss requiring a blood transfusion. However, percutaneous screw placement does not appear to have an advantage for other outcomes including screw accuracy, robot reliability, reoperations, and length of hospital stay. Future multicenter studies on longer fusion surgeries and in the inclusion of patient-reported outcomes are needed.

106

P386: Neurological and Other Major Complications of Minimally Invasive Spinal Decompressive Surgery. Should we Revisit Information Given to Patients Before Consent?

Triantafyllos Bouras ¹

¹ CHWAPI, Neurosurgery, Tournai, Belgium

Introduction: Minimally invasive decompressive spine surgery is often proposed to patients with radicular compression syndromes or lumbar canal stenosis. Complications are rare and by this study we aim to estimate if the possibility for severe neurological complications is realistic for this kind of surgery. Material and Methods: One hundred fifty patients were reviewed for intra-operative and immediate post-operative complications. The relevant literature was also reviewed. The results were compared to a list of official consent forms for spinal decompressive surgery concerning eventual complications. Results: In our series, the overall major complication rate was 3%: One deep venous thrombosis and one deep post-operative infection were recorded. Two operations (3%) were complicated by dural tears, sealed with biologic glue, with no further consequence for the patients after 48-hour immobilization. No neurological complications were recorded. Ten (6.6%) presented local intramuscular hematomas, which resolved spontaneously. In the relevant literature, in six articles dedicated to complication analysis after minimally invasive decompressive surgery, and a total of 1532 patients, the permanent neurological complication rate was zero. All the reviewed consent forms mentioned paraplegia as a rare (<1%) and partial paralysis as an unusual (1-5%) eventual complication. Conclusion: Patients with radicular symptoms, refractory to conservative treatment of a reasonable duration, without present or imminent instability, should be encouraged to undergo minimal invasive decompressive surgery based not only to the well-known highly possible satisfactory clinical outcomes, but to the minimal risk of the procedures as well. This fact should be made clearer in the relevant consent forms.

120

P387: Thoracic Disc Herniations. Differential Choice of Surgical Approach

Roman Khalepa ¹

¹ FSBI "Federal Neurosurgical Center", Spinal neurosurgical department, Novosibirsk, Russian Federation

Introduction: Thoracic disc herniation is rare condition, with an estimated frequency of 1 per 1,000,000 people. Surgical procedures in the thoracic spine make up only 0.15% to 4% of the procedures for disc herniation. Surgery for thoracic disc herniation has a poor reputation because of its unfamiliar to surgeons, technical difficulties and the risk of complications. Surgical procedures are classified as posterolateral and transthoracic approaches. An understanding of the available techniques is essential to help the surgeon choose an appropriate strategy. Material and Methods: From 2013 to 2020, 34 patients with symptomatic thoracic disc herniations were operated on. The average age of patients was 54 years (28-80). Frankel scale used to objectify and standardize the clinical features of the disease before and after surgical treatment. Indications for surgery were radiculopathy, myelopathy. MRI, CT were used to determine the localisation of disc herniation and its consistency and to plan a surgical procedure. The choice of surgical approach based on localisation of the disc herniation. In 16 cases of central giant calcified disc herniations, transthoracic approach with endoscopic assistance was the method of choice. In 18 cases of paramedian and lateral disc herniations used posterolateral approach. Clinical outcome defined during 24 months after surgery by Frankel scale. Results: Neurological deficite before surgery in cases of central disc herniations: Frankel A - 1, B - 0, C - 6, D – 9. Neurological deficite before surgery in cases of paramedian and lateral disc herniations: Frankel A - 0, B - 0, C - 6, D – 12. There was no statistically significant difference in neurological deficite between these groups before surgery (P = .834). Neurological deficite after surgery in cases of central disc herniations: Frankel A - 0, B - 0, C - 2, D – 9, E - 5. Neurological deficite after surgery in cases of paramedian and lateral disc herniations: Frankel A - 0, B - 0, C - 2, D – 11, E - 5. There was no statistically significant difference in neurological deficite between these groups after surgery (P = 1). Intraoperative blood loss (mean 450 ml), time of surgery (mean 225 min) and postoperative hospital stay (7 days) in cases of transthoracic approach was statistically significant greater than in group of posterolateral approach: blood loss (mean 117 ml), time of surgery (mean 120 min) and postoperative hospital stay (4 days); P = .0028; P = .00029; P = ,02 respectively. In both groups improvement in neurological status 17 (58%); without improvement 10 (34%); neurological deterioration with recovery to the original in the long-term period 2 (8%). Complications: posterolateral approach 3 (16%) complications: 2 incidental durotomy and 1 neurological deterioration. transthoracic approach 3 (18%) complications: 1 incidental durotomy and 1 neurological deterioration. There was no statistical difference between groups (P = 1). Conclusion: - The choice of the optimal approach based on localisation of disc herniation reduce the risk of post-operative neurological complications. - The differentiated application of surgical approaches ensures the achievement of comparable functional results.

152

P388: Advantages of Endoscopic Surgery in Patients With Disc Hernia - Literature Systematic Review

Ricardo César Cortes de Bom ¹ , Rian Souza Vieira ² , Luiz Humberto Faria Barbosa ¹ , Guilherme Jose Coelho Dias ¹ , Erotides de Souza Vilas Boas Neto ¹ , Marina Marangon Melhado ¹ , and Natalia Rizzato Alecio ¹

¹ Beneficencia Portuguesa, Ortopedia e Traumatologia, Ribeirao Preto, Brazil

² FMRP - USP, Ortopedia e Traumatologia, Ribeirao Preto, Brazil

Introduction: Herniated disc (HD) is characterized by displacement of the contents of the intervertebral disc, the pulposus nucleus (PN), which leaks out of the membrane, with possible bulging of the PN. Spinal Endoscopic Surgery (EC) is a low-invasive technique, with less tissue damage, preservation of paravertebral muscles, shorter hospital stay and morbidity, with early return to activities. Material and Methods: This is a cross-sectional literature review, analytical in nature with articles published in the period from 2016 to 2020. Results: The results show that endoscopic surgery is effective in the treatment of herniated disc with shorter recovery time and complication rate even in high-risk patients, when compared to conventional techniques. This low-invasive technique prove to be effective also in the treatment of obese people. The use of the camera has a success rate of up to 97% in the studies evaluated, with 33% lower infection rate. Due to the fact of minimal incision and little manipulation of tissues, patients present an important reduction in pain when compared to other techniques. Conclusion: In view of the results found, it was possible to perceive that endoscopic surgery has benefits for patients. Although the surgical process in the region of the spine is a cause for concern for both patients and doctors; the procedure allows local approaches, without major trauma to patients. Further studies on the subject are necessary in order to clarify the procedures, however, the studies already carried out give a positive view regarding the promising results.

198

P389: Biportal Endoscopic Approach for Highly Up-Migrated Disc in the Hidden Zone: A Technical Feasibility and Early Clinical Outcomes

Cheol Woong Park ¹ and Nandan Marathe ²

¹ Daejeon Woori Hospital, Spine Surgery, Daejeon, South Korea

Toronto Western Hospital, Orthopedic Surgery, Toronto, Canada

Introduction: The aim of this study is to introduce the one level above contralateral sublaminar unilateral biportal endoscopic (OLACS UBE) surgery for highly up-migrated disc and to share the preliminary clinical and surgical outcomes. Materials and Methods: This study was conducted at a tertiary care spine hospital from January to December 2019. Patients with highly up-migrated disc were included in the study. All patients were operated by OLACS UBE approach. Patients were re-evaluated post-surgery by MRI to confirm the successful removal. Back and leg pain was evaluated by Visual analogue scale (VAS) for pain. The satisfaction rate of clinical outcomes was assessed according to the modified MacNab criteria. Results: Thirteen patients were operated by the OLACS UBE approach for a highly up-migrated disc. The mean age of the patients was 60.8 years. The average operative time and mean follow-up period were 75.8 minutes and 4.1 months. Compared to pre-operative scores, the VAS of back and leg pain in all patients was reduced significantly (P < .001). At final follow-up, 12 of 13 patients had favourable outcome as per the MacNab criteria. One patient had unfavourable outcome due to presence of residual leg pain at final follow-up after surgery. Conclusion: One level above contralateral sublaminar unilateral biportal endoscopic surgery may be considered as an alternative approach for treatment of highly up-migrated disc. A study with a larger sample size and a longer follow-up is needed to further validate our findings.

Keywords

highly up-migrated disc; hidden zone; One level above; Contralateral; Sublaminar; Biportal endoscopic surgery; OLACS UBE

References

1. Akbary K, Kim JS, Park CW, Jun SG, Hwang IC. The Feasibility and Perioperative Results of Bi-Portal Endoscopic Resection of a Facet Cyst Along With Minimizing Facet Joint Resection in the Degenerative Lumbar Spine. Oper Neurosurg (Hagerstown). 2019;24.

2. Hwang JH, Park WM, Park CW. Contralateral Interlaminar Keyhole Percutaneous Endoscopic Lumbar Surgery in Patients with Unilateral Radiculopathy. World Neurosurg. 2017;101:33-41.

3. Yeom KS, Choi YS. Full endoscopic contralateral transforaminal discectomy for distally migrated lumbar disc herniation. J Orthop Sci. 2011;16:263-269.

4. Kim JS, Choi G, Lee SH. percutaneous endoscopic lumbar discectomy via contralateral approach: a technical case report. Spine (Phila Pa 1976). 2011;36:E1173-E1178.

5. Wu PH, Kim HS, Jang IT. How I do it? Uniportal full endoscopic contralateral approach for lumbar foraminal stenosis with double crush syndrome. Acta Neurochir (Wien). 2020;162:305-310.

6. Krzok G, Telfeian AE, Wagner R, Iprenburg M. Transpedicular Lumbar Endoscopic Surgery for Highly Migrated Disk Extrusions: Preliminary Series and Surgical Technique. World Neurosurg. 2016;95:299-303.

7. Quillo-Olvera J, Akbary K, Kim JS. Percutaneous endoscopic transpedicular approach for high-grade down-migrated lumbar disc herniations. Acta Neurochir (Wien). 2018;160:1603-1607.

200

P390: Anatomic Considerations and Functional Outcomes of Endoscopic Transiliac Approach for Access to L5-S1 Disc and Foramen

Nandan Marathe ^{1 2} and Prasad Patgaonkar ³

¹ Indore Spine Centre, Spine Surgery, Indore, India

² Toronto Western Hospital, Orthopedic Surgery, Toronto, India

³ Indore Spine Centre, Indore, India

Introduction: Transforaminal endoscopic disc surgery has several advantages as compared to open surgery. However, the efficacy of the procedure is in doubt when the conventional transforaminal approach is obstructed by anatomic barriers. One such difficult to access locations is L5-S1 disc. The purpose of the present study is to analyze the functional outcomes of endoscopic discectomy with transiliac approach at L5-S1 level and also provide details of the surgical technique. Materials and methods: This study was carried out over a period of 3 years (2015-2018) at a tertiary care spine hospital. Patients with a disc herniation at L5-S1 level were classified as per the method described by the same author that has been previously published. Only those patients requiring transiliac approach were included in the study. To ensure no bias, all patients were operated by the same surgeon who is also the lead author of this paper. We report the functional outcome data obtained during the 2 year postoperative follow-up period using VAS score and ODI. Results: Transforaminal endoscopic discectomy was performed through transiliac approach in 62 patients. The VAS score improved from 8.31 to 2.25 (P value < .05). The ODI score also improved from 70.23 to 17.71 (P value < .05). No patient deteriorated neurologically, one patient had recurrence at same level managed using selective nerve root block, one patient had recurrent disc herniation managed using the inter laminar approach. Conclusion: Difficulty in using transforaminal approach to L5–S1 space is because of multiple anatomic barriers. Advantages of transiliac approach include easy removal of central, foraminal or up migrated disc fragment, no damage to S1 endplate, reduced risk of injury to exiting nerve root, ease of foraminoplasty, access to the epidural space. Transiliac endoscopic discectomy is safe and effective for lumbosacral disc pathologies. It can be performed with marking under fluoroscopy with simple orthopaedic instruments under local anesthesia. It negates limitations of transforaminal approach for L5–S1 disc.

Keywords

transiliac approach; endoscopic spine surgery; lumbo sacral junction

References

1. OsmanSG, MarsolaisEB. Endoscopic transiliac approach to L5–S1 disc and foramen. A cadaver study. Spine 1997; 22:1259–63.

2. Eksioglu F, Uslu M, Gudemez E, et al. Reliability of the safe area for the superior gluteal nerve. Clin Orthop Relat Res 2003; 412:111– 6.

3. LuJ, EbraheimNA, HuntoonM, et al. Anatomic considerations of superior cluneal nerve at posterior iliac crest region. Clin Orthop Relat Res 1998; 347:224

4. Choi G, Lee SH, Raiturker PP, et al. Percutaneous endoscopic interlaminar discectomy for intracanalicular disc herniations at L5–S1 using a rigid working channel endoscope. Neurosurgery 2006;58(suppl 1): ONS59-68; discussion ONS59-68.

240

P391: Hidden Blood Loss Following Percutaneous Endoscopic Lumber Discectomy (PELD): A Prospective Study

Chong Chen ^{1, 2} , Guoyan Liang ^{1, 2} , Honglin Gu ^{1, 2} , anf Yunbing Chang ^{1, 2}

¹ Guangdong Provincial People's Hospital, Spine Department, Guangzhou, China

² Guangdong Academy of Medical Science, Guangzhou, China

Introduction: PELD is a minimally invasive technique for treatment of lumbar disc herniation (LDH) that requires only an eight-mm skin incision and promotes faster recovery. It is widely believed that the procedure is associated with minimal blood loss. However, significant perioperative hidden blood loss (HBL) is frequently unaccounted for. Material and Methods: In total, 112 patients undergoing PELD were enrolled. The factors analyzed included gender, age, body mass index (BMI), operation approach/technique, operation duration, improvement in the visual analog scale (VAS), Japanese Orthopedic Association (JOA) and the Oswestry disability index (ODI) scores, and the presence of associated chronic diseases (e.g., hypertension, rheumatoid arthritis, and diabetes mellitus). According to Gross’s formula, patient height, weight, and pre-operative and post-operative hematocrit were recorded and used to calculate the resultant blood loss. Possible contributary factors were analyzed by multivariate linear regression analysis and t test. Results: The mean HBL was 303 ± 204 mL, and the post-operative Hb loss was 9.6 ± 6.7 g/L. A lateral surgical approach was associated with increased HBL compared to an interlaminar approach. However, no significant difference in improvements of the VAS, JOA, or ODI scores was noted between the two surgical approaches. Increased surgical times and foraminal decompression were found from multivariate linear regression analysis to be linked to increased HBL. As expected, the incidence of post-operative anemia was significantly associated with HBL. Age, gender, BMI and associated chronic diseases did not associate with increased HBL following PELD. Conclusion: HBL is increased in PELD patients with longer surgical times and lumbar foraminal decompression. Other patient demographic characteristics were not associated with increased peri-operative bleeding.

277

P392: Minimally Invasive Treatment of Thoracolumbar Injuries

Alfredo Guiroy ¹ , Federico Landriel ² , Ruben Morales Ciancio ¹ , Alfredo Sicoli ¹ , Nicolas Gonzalez Masanes ¹ , Martin Gagliardi ¹ , anf Santiago Hem ²

¹ Spanish Hospital, Orthopedics, Mendoza, Argentina

² Hospital Italiano, Neurosurgery, Buenos Aires, Argentina

Introduction: We aim to analyze and describe a series of trauma-related thoraco-lumbo-sacral vertebral fractures managed with minimally invasive surgery. Material and Methods: We retrospectively review the charts and images of 26 patients with thoracolumbar spine fractures between 2010-2017. Pre-op images were assessed and fractures were classified according to the thoraco-lumbar trauma AO Spine classification. We analyzed: pre and post-surgical visual analog scale (VAS), blood loss during surgery, hospital length of stay, complications, associated surgical procedures, long term post-op implant removal, pre and post neurological status and mortality. Patients with a complete case record, pre-op CT scans and minimum 12-month follow up were included (18 males and 8 females). Mean age was 28.7 years (21-84 years); mean post-op follow up was 28 month (13-86 months). Eighteen patients were managed with percutaneous instrumentation, 8 patients also received percutaneous vertebroplasty, and 5 patients underwent also some arthrodesis procedure. Results: VAS improved 7 points as compared to the pre-op score; mean blood loss was 40 mL, we did not observed any neurological deficit worsening. Mean hospital length of stay was 3.9 days. Four patients needed surgical procedures involving other organs due to politrauma. Percutaneous screws were removed in 9 cases after fracture consolidation. Complications were: one case of self-limiting retroperitoneal hematoma, one case of pedicle screw fracture and one cement broken cannula into the pedicle. Conclusion: Minimally invasive surgery in spine trauma is a valid option allowing stabilization, early mobilization, and leading to good outcomes in terms of pain control and a lower complication rate.

279

P393: Teaching, Training and Surgical Education in MISS. Do we Have any Experience and Data?

Alfredo Guiroy ¹ , Asdrubal Falavigna ² , and Néstor Taboada ³

¹ Spanish Hospital, Orthpedics, Mendoza, Argentina

² Caxias do Sul University, Neurosurgery, Caxias do Sul, Brazil

³ Clinica Portoazul, Neurosurgery, Barranquilla, Colombia

Introduction: Advances in new technologies give the surgeons confidence to manage complex spine conditions with a lower morbidity rate. This has changed the expectations of patients and medical payers’, and foreshadows the shift now underway: the use of minimally invasive techniques. The ethical considerations of learning directly on patients required a change in the education and training programs. Methods: The education paradigm has changed, and surgical training on MISS techniques should follow a “curriculum”. The assessment of skill proficiency while learning the MISS techniques must be measurable to objectively show the performance gained over time and the changes that should be performed during training. Different strategies include “ex vivo” and “in vivo” training. Results: We have worked on a curriculum in which the participants can perceive the growth in their knowledge through the different educational opportunities. There are 3 levels: basic, advanced and masters. Conclusions: We developed an educational curriculum for MISS rationale and techniques, that showed to be effective and interesting in our region.

304

P394: Access to Technology and Education for the Development of Minimally Invasive Spine Surgery Techniques in Latin America

Alfredo Guiroy ¹ , Martin Gagliardi ¹ , Juan Pablo Cabrera Cousio ² , Nicolas Coombes ³ , André de Oliveira Arruda ⁴ , Néstor Taboada ⁵ , and Asdrubal Falavigna ⁶

¹ Spanish Hospital, Mendoza, Argentina

² Hospital Clinico de Concepción, Concepcion, Chile

³ Axial Medical Group, Buenos Aires, Argentina

⁴ Instituto Columna, Belo Horizonte, Brazil

⁵ Clínica Portoazul, Barranquilla, Colombia

⁶ University of Caxias do Sul, Caxias do Sul, Brazil

Introduction: The objective of this paper is to evaluate access to technologies and education needed to perform minimally invasive spine surgery in Latin America. Material and Methods: We designed a questionnaire to evaluate surgeons’ characteristics, their possibilities to access different technologies and their training opportunities in minimally invasive spine surgery techniques. The survey was sent to members and registered users of AO Spine Latin from January 6^th to -20^th, 2020.The major variables studied were nationality, specialty (orthopedics or neurosurgery), level of complexity of the hospital, number of surgeries performed per year by the spine surgeon, types of spinal pathologies commonly managed, number of minimally invasive spine surgeries performed per year. Other variables involved specific access to different technologies: fluoroscopy during the procedures, access to percutaneous screws, cages, tubular retractors, microscopy, intraoperative CT, navigation and bone morphogenetic protein (BMP). Finally, participants were asked about the main limitations and access to education in these techniques in the region. Results: The questionnaires were answered by 306 members of AO Spine Latin America from 20 different countries. Most answers were obtained from orthopedic surgeons (57.8%) and those with more than 10 years of experience (42.4%). Most of the surgeons worked in private practice (46.4%), performed more than 50 surgeries per year (44.1%), but only 13.7% performed more than 50 minimally invasive spine surgeries per year, mainly to manage degenerative pathologies (87.5%). Most surgeons always had access to fluoroscopy (79%). Only 26% always had access to percutaneous screws, 24% to tubular retractors, 34.3% to cages (ALIF, LLIF or TLIF) and just 43% always had access to microscopy. About technologies, 71% never had access to navigation, 83% never had intraoperative CT and 69.3% never had BMP. The main limitations found for widely used MISS technologies were high implant cost (69.3%) and the high navigation cost (49.3%). Most surgeons had access to online education activities (71%), but only 44.9% had access to face to face events and 28.8% to hands on activities; this was mainly because the courses were expensive (62.7%) or there are few courses available in the region on this topic (51.3%).Conclusion: Most surgeons in Latin America had limited resources to perform minimally invasive spine surgery even in private practice. The main constrain mentioned was implant cost, technologies and face to face education opportunities.

370

P395: Results of Unilateral Pedicle Screw Fixation of the Lumbar Spine With Minimally Invasive Laser Osteoperforation of the Facet Joints

Alexey Lychagin ¹ , Vadim Cherepanov ¹ , Sergey Ivannikov ¹ , and Ivan Vyazankin ¹

¹ Sechenov University, Traumatology, Orthopedics and Disaster Surgery, Moscow, Russian Federation

Introduction: Lumbar spine pain is the second most common cause of temporary disability in the world after acute respiratory infections. Oftentimes, the pain syndrome can be associated not only with the occurrence of degenerative changes in the spinal canal, but also with changes in the posterior column of the spine. Facet joints undergo secondary degenerative changes, which are the result of constant overstrain of the paravertebral muscles and constant stress on the spinal motion segment (VMS), which can lead to spondyloarthrosis, synovial cysts, as well as instability of the VMS. The goal of this study was to develop method for the surgical treatment of degenerative changes in the spinal canal of the lumbar spine, and to assess its effectiveness. Material and Methods: We present the experience of surgical treatment of single-level degenerative diseases of the lumbar spine in 82 patients aged 54 to 79 years, of which 53 (64.6%) were women, 29 (35.4%) were men. All patients underwent surgical treatment in the period from 2016 to 2019. The surgery method was to install a system of unilateral pedicle screw fixation with the use of decompression of neural structures from the affected side. Then, under the C-arm, a puncture minimally invasive laser perforation of the facet joints of the spine from the contralateral side was performed according to the technique developed at the Department of Traumatology, Orthopedics and Disaster Surgery of Sechenov University. The examination protocol for all patients included orthopedic and neurological examination, spondylography, computed tomography and magnetic resonance imaging (MRI). To rate the quality of life and the level of daily activity of patients, the EuroQol 5 Dimensions scale (EQ-5D) and the Oswestry Disability Index (ODI) questionnaire were used. The results were rated in the preoperative period, in the early postoperative period (3 months) and in the late postoperative period (12 months). Results: According to the results obtained, there is a persistent decrease in pain syndrome and an improvement in the quality of life of patients after surgical treatment. EQ-5D before surgery was .009 ± .234, after 3 months .879 ± .126 and decreased to .735 ± .165 in the late postoperative period. According to the Oswestry Disability Index questionnaire, the ODI was 73.74 ± .53 before surgery, 23.42 ± .29 in the early postoperative period and decreased to 27.44 ± .35 12 months after surgery. Conclusion: The results obtained during studies show a significant improvement in the quality of life of the operated patients, due to a persistent reduction in pain syndrome and an improvement in daily activity. The minimal invasiveness and precision of the proposed tactics of surgical treatment helps reduce traumatism, shorten the operation time, and also reduce the number of implants installed, which in sum proves its effectiveness.

448

P396: Prospective Comparative Study of Functional Outcomes of Open vs Minimally Invasive Spine Surgery in Degenerative Lumbar Pathology

Ayush Sharma ¹ , Priyank Deepak ¹ , Vijay Singh ¹ , Nilesh Mangale ¹ , and Ajay Jaiswal ¹

¹ Central Railway Hospital, Department of Orthopaedic and Spine Surgery, Mumbai, India

Aim: Aim of the study was to compare the functional outcome of open vs minimally invasive spine surgery in degenerative lumbar pathology. Material and Methods: All patients undergoing surgery for degenerative lumbar pathology were prospectively followed for one year. VAS (Visual analogue score), ODI (OswestryDisability Index) were used to analyse the functional outcome at postoperative period day one, two weeks, One month, three months, Six months and one year. Data was divided into an open and minimally invasive group (MIS) and analysed. P value < .05 was taken as significant. Result: 488 patients were included in the final analysis. 164 were from the MIS group and 242 underwent open surgery. TLIF was done 142 patents of which 56 (39.4%) underwent MIS TLIF. 240 patients were operated for discectomy of which 104 (43.3%) were from MIS group. While pre-operative mean VAS scores were comparable for both the groups. Follow up VAS scores were significantly better for MIS group at postoperative day one(P = .001), two weeks(P = .001), One month(P = .001), three months(P = .003) and Six months. (P = .023). Similarly ODI scores were also significantly better for MIS group at postoperative day one (P = .004), two weeks (P = .001) and one months(P = .003). No significant difference was found between one year VAS scores between the two groups (P = .145). Similarly ODI scores were comparable between the two groups at three months, Six months and one year. Incidence of dural tear was significantly less (6.4%) in the minimally invasive group compared to open surgery (15.7%) (P = .01). Conclusion: Functional outcomes of minimally invasive surgery for degenerative lumbar pathology are comparable with open surgery with significantly improved VAS scores up to 6 months and significantly better ODI scores up to one month.

454

P397: Ultrasonic Bone Scalpel for Thoracic Spinal Decompression: Case Series and Technical Note

Guanghui Chen ¹ , Chuiguo Sun ¹ , and Zhongqiang Chen ¹

¹ Peking University Third Hospital, Beijing, China

Introduction: Thoracic spinal stenosis (TSS) is a rare but intractable disease that fails to respond to conservative treatment. Thoracic spinal decompression, which is traditionally performed using high-speed drills and Kerrison rongeurs, is a time-consuming and technically challenging task. Unfavorable outcomes and high incidence of complications are the major concerns. The development and adaptation of ultrasonic bone scalpel (UBS) has promoted its application in various spinal operations, but its application and standard operating procedure in thoracic decompression have not been fully clarified. Therefore, the purpose of this study is to describe our experience and technique note of using UBS, and come up with a standard surgical procedure for thoracic spinal decompression. Material and Methods: A consecutive of 28 patients with TSS who underwent posterior thoracic spinal decompression surgery with UBS between December 2014 and May 2015 were enrolled in this study. Results: Thoracic spinal decompression surgery was successfully carried out in all cases via a single posterior approach. The mean operative time of single-segment laminectomy was 3.0 ± 1.4min and the blood loss was 108.3 ± 47.3ml. In circumferential decompression, the average blood loss was 513.8 ± 217.0ml. Two cases of instrument-related nerve root injury occurred during operation and were cured by conservative treatment. Six patients have experienced cerebrospinal fluid (CSF) leakage postoperatively, but no related complications were observed. Conclusion: The UBS is an optimal instrument for thoracic spinal decompression, and its application enables surgeons to decompress the thoracic spinal cord safely and effectively. This standard operating procedure is expected to help achieve favorable outcomes, and can be used to treat various pathologies leading to thoracic spinal stenosis.

504

P398: Long-Term Results of Minimally Invasive Transforaminal Lumbar Interbody Fusion in Elderly Patients: A 5-Year Follow-up Study

Graham Goh ¹ , Gerald Zeng ¹ , Yogen Thever ¹ , and Reuben Soh ¹

¹ Singapore General Hospital, Singapore, Singapore

Introduction: Minimally invasive transforaminal lumbar interbody fusion (MIS TLIF) may be particularly beneficial for elderly patients due to decreased surgical morbidity and faster postoperative recovery. However, no studies have evaluated the long-term outcomes of MIS TLIF in this subpopulation. This study compares the clinical and radiological outcomes between elderly patients and younger controls undergoing MIS TLIF at a minimum follow-up of 5 years. Materials and Methods: Patients who underwent a primary single-level MIS TLIF for degenerative spondylolisthesis were retrospectively reviewed and stratified into two cohorts: elderly (≥70 years) and controls (<70 years). The cohorts were matched in a 1:3 ratio for sex, body mass index, American Society of Anesthesiologists (ASA) class, comorbidities and preoperative PROs using propensity scoring. Complications, length of stay and readmissions were recorded. Patient-reported outcomes (PROs) including the Oswestry Disability Index (ODI), 36-Item Short-Form Physical Component Score (SF-36 PCS), Mental Component Score (SF-36 MCS), Visual Analogue Scale (VAS) back pain, and VAS leg pain were compared at 6 months, 2 years and 5 years. Satisfaction was assessed using the North American Spine Society (NASS) questionnaire. Radiographic fusion and adjacent segment degeneration (ASD) were assessed. Revision procedures were recorded. Mean follow-up was 7.2 ± 3.0 years. Results: In total, 30 elderly patients and 90 controls were included. Elderly patients had a longer length of stay (4.7 ± 5.8 days vs 3.3 ± 1.4 days, P = .035) and more readmissions (10% vs 1%, P = .019), but there was no difference in operative time, transfusions, complications or discharge disposition. With the exception of better VAS leg pain in elderly patients at 2 years (P = .037), there was no difference in ODI, VAS back pain, VAS leg pain, SF-36 PCS and SF-36 MCS up to 5 years postoperatively. Both cohorts demonstrated similar satisfaction rates (93% in elderly vs 91% in controls, P = .703) and achievement of MCID for each PRO. Radiographic fusion was 94% and 97% in the control and elderly groups, respectively (P = .605), while 40% and 33% had radiological ASD (P = .503). There were 3 revisions (3.3%) in the control group (2 for ASD, 1 for screw loosening) but none in the elderly group (P = .311). Conclusion: Elderly patients undergoing MIS TLIF not only had similar perioperative outcomes, but also achieved comparable improvements in pain, disability and quality of life that were sustained for up to 5 years with no longer-term deterioration.

516

P399: Impact on Length of Stay of Local Anesthetic Injection During Minimally Invasive Lumbar Spinal Fusion

Christian Ivan Lucas Fras ¹ , Sebastian Fras ¹ , and Christian Fras ¹

¹ Institute for Spinal Surgery, Broomall, USA

Introduction: Current practice in many areas of surgery includes infiltration of the subcutaneous tissues with local anesthetic to assist with post-operative pain control. In the course of performing lumbar spine surgery, including minimally invasive lumbar spinal fusion, many surgeons routinely inject local anesthetic into the wound before closure of the incision in the expectation that this will yield improved post-operative pain control, and therefore a shorter length of stay. However, to date there has been no rigorous study investigating the actual impact of this technique in the setting of spine surgery. This investigation seeks to assess the impact of subcutaneous injections of local anesthetic on length of stay after minimally invasive lumbar spinal fusion surgery. Materials and Methods: Twenty-five consecutive patients (Group 1) underwent single level minimally invasive lumbar spine surgery, the surgery consisting of a one-level laminotomy and posterior spinal fusion with spinous process clamp and allograft bone graft; in these initial 25 patients, there was no injection of any local anesthetic. Thereafter, in the subsequent 25 patients (Group 2) undergoing the same procedure (one-level laminotomy and posterior spinal fusion with spinous process clamp and allograft bone graft), local anesthetic (30 cc of lidocaine with epinephrine) was injected into the subcutaneous tissues. Surgical procedure time and post-operative hospital length of stay (LOS) was recorded for all 50 patients and compared. Results: Mean Group 1 surgical procedure time was noted to be 61 minutes (range 50-70 minutes); mean Group 2 surgical procedure time was noted to be 59 minutes (range 51-73 minutes). There was no statistical difference in the surgical procedure time between the two groups (P > .05). Mean Group 1 LOS was 3.1 days (range 2-4 days); mean Group 2 LOS was 3.2 days (range 2-4 days). There was no statistical difference in the duration of LOS when comparing the two groups (P > .05). Conclusion: In several studies outside the spine surgery arena, use of local anesthetic wound infiltration in surgical procedures has been found to decrease post-operative pain and LOS; however, while a commonly used technique by spine surgeons, its use has not been critically evaluated in the field of spine surgery, particularly in minimally invasive lumbar fusions. The results of this study suggest that injecting local anesthetic into the subcutaneous tissues as part of a minimally invasive lumbar decompression and fusion does not have any impact on post-operative length of stay. Further research may refine these results, but the current study does not support local anesthetic injection as a method of controlling pain and reducing hospital LOS in minimally invasive lumbar spinal fusion surgery.

556

P400: Designed Awl Technique Versus Conventional Jamshidi Method for Percutaneous Pedicle Screw Insertion in Minimally Invasive Transforaminal Lumbar Interbody Fusion - A Prospective Cohort Study

Meng-Yin Ho ¹ and Fon-Yih Tsuang ²

¹ National Taiwan University Hospital Hsinchu Branch, Division of Neurosurgery, Department of Surgery, Hsinchu City, Taiwan

² National Taiwan University Hospital, Division of Neurosurgery, Department of Surgery, Taipei city, Taiwan

Introduction: Minimally invasive spine surgery (MISS) has become more common in current practice. Many review studies mentioned that MISS had the trend of reduced blood loss, lower infection rate, decreased operative time, and decreased length of stay. However, it brought surgeons more radiation exposure while using X-ray machine. In 2017, we proposed another method for percutaneous screw insertion with our designed instrument, which only requires anterior-posterior (AP) view of intraoperative fluoroscopy. This instrument combined the function of awl, pedicle finder, and tapper. Previous published technical note¹ proved that it decreased X-ray shots. This time, we aim to confirm surgical outcomes of MISS with this designed awl. Typically, in MISS, Jamshidi needle was used to cannulate pedicle under intraoperative fluoroscopy. Instead of it, we used designed awl to perform percutaneous pedicle screw insertion. Materials and Methods: Instrument Design: The designed awl is composed of cannulated trocar and cap that is fixed with a shortened Kirschner wire. The trocar has an anterior slender portion providing pedicle finder function, and it creates the projection line (PL) on the AP view of fluoroscopy. We adjusted the insertion angle according to the PL and don’t need the lateral views while inserting the pedicle screws. Study Design: Retrospectively, 444 cases were enrolled for prospective MI-TLIF cohort between January 2014 to December 2019 at three hospitals (National Taiwan University Hospital Taipei Branch, National Taiwan University Hospital Yunlin Branch, Taipei Municipal Wanfang Hospital). 271 cases of them received percutaneous screw in MI-TLIF with the designed awl, and the other 173 cases with Jamshidi needle. The primary outcomes were: (1)operative time; (2)length of hospitalization; (3)blood loss during operation; and (4)post-operative complications within 30 days. We compared outcomes of these two different methods for MI-TLIF with population analysis, univariate analysis, and multivariate analysis with SAS, and P values< .05 were considered statistically significant. Results: Four primary outcomes were compared. Operative time and length of hospitalization were significantly lower (both P < .001) in the designed awl group, and there was no significant difference in blood loss. But there is a trend that there is less instrument-related complications within 30 days in the designed awl group. Adjusting confounding factors (year of operation and operation level), operative time(P < .001), length of hospitalization(P < .001), and blood loss(P = .01) were significantly lower in the designed awl group in multivariate analysis. After approving better outcomes with this new method, we investigated the efficacy how the designed awl works with different percutaneous pedicle screws system. With the same surgeon, 114 cases were selected(manufacturer 1(N = 58) vs manufacturer 2(N = 56)). We found out there were no significantly different outcomes between manufacturer 1 and 2. Conclusion: The awl we designed not only let surgeons have lesser radiation exposure¹ but also improved surgical outcomes. Patients had lesser operative time, length of hospitalization, and blood loss with the designed awl. It was suitable for different percutaneous pedicle screws system, so surgeons could use it with any system they preferred. The outcomes did not have significant difference between different systems. Therefore, the designed awl may be an adequate instrument to improve MI-TLIF course and result.

591

P401: A Single Segment Minimally Invasive Transforaminal Fusion of Lumbar Spine With Unilateral Pedicle Screw Fixation - A Short Term Analysis and Comparison Between Successful and Failed Group

Teodor Trojner ¹ , Milko Milčič ¹ , and Gregor Rečnik ¹

¹ University Medical Centre Maribor, Department of Orthopaedics, Maribor, Slovenia

Introduction: We wanted to clinically and radiologically compare results between two groups of patients with unilateral fixation of minimally invasive transforaminal lumbar interbody fusion (unilateral fixation of MINI TLIF); those with a successful outcome and those that required a revision procedure with bilateral fixation. Material and Methods: Thirty-two adults (nineteen males, thirteen females) aged 57.4 ± 10.9 years and with BMI 27.4 ± 3.4kg/m² were included. Patients had failed conservative treatment and were surgically treated for a single-level degenerative lumbar spine disease. Indications for surgery were symptomatic herniated disc, foraminal stenosis, degenerative disc disease, and spinal stenosis. Prior to the unilaterally fixated MINI TLIF with a single cage insertion, they were clinically and radiologically evaluated. Pain in lower extremities and lower back, as well as disability score, were assessed with Visual Analogue Scale (VAS) and Oswestry Disability Index (ODI). Standing anteroposterior (AP) and lateral x-rays of lumbar spine were performed to measure segmental lordotic angle (SLA), segmental scoliotic angle (SSA), and intervertebral disc height (IDH). The SLA and SSA were measured between a proximal endplate of the cranial vertebral body and distal endplate of the caudal vertebral body, while IDH was measured between centres of two adjacent vertebral body endplates. Same measurements were taken immediately after the surgery and at follow-up examination after 6 – 12 months. Results: The level of pathology was L2-L3 in 6.3%, L3-L4 in 28.1%, L4-L5 in 46.9%, and L5-S1 in 18.8%. In 46.9% we used PEEK, while in 53.1% we used Trabecular Metal (TM) cages. Twenty-seven patients achieved a full recovery with minimal or no remaining pain on follow-up (group A), while five required revision surgery with bilateral fixation (group B). In all cases in group B, the pathologic level was L4-L5 and TM cages were inserted. Immediately after the procedure, an increase in SLA (13.2° to 15.3°) and IDH (9.3 mm to 12.0 mm) were observed. However, an important decrease in SLA and IDH ensued on follow-up (to 13.1° and 10.6 mm; respectively). Nevertheless, a decrease in ODI (.66 to .35) and VAS_back (7.0 to 3.7) was evident after surgery even at follow-up in all patients. Higher ODI and VAS_back were noted in group B on follow-up compared to group A (namely, .56 and 5.6 compared to .31 and 3.3, respectively). Although lower SSA was detected immediately after the primary procedure in the later revised group compared to group A (1.5° compared to 3.1°), a significant increase in SSA was observed in group B on follow-up prior to revision surgery (1.5° to 4.0°) with no such increment in group A. Conclusion: Our results suggest that it is possible to achieve a limited improvement of segmental lordosis and intervertebral disc height with unilateral fixation of MINI TLIF. Subsidence of the intervertebral cage with loss of segmental lordosis seems to occur at time goes by. A simultaneous coronal disbalance could be a predictive factor for failure and revision surgery in some patients. Identifying those patients at risk might prove beneficial in determining a need for primary bilateral fixation.

647

P402: Technical Tips for Percutaneous Transforaminal Endoscopic Discectomy: A Three-Step Maneuver for Puncture and Early Clinical Experience

Zeyan Liang ¹ , Xinyao Chen ¹ , Xiongjie Xu ¹ , Chunmei Chen ¹ , and Rui Wang ¹

¹ Fujian Medical University Union Hospital, neurosurgery, Fuzhou, China

Introduction: The transforaminal puncture method currently employed in PTED depends on a constant distance from the midline and estimated angles in anteroposterior and craniocaudal directions. A three-step maneuver for puncture (TSMP) is an alternative concept of puncture based on Kambin’s triangle. TSMP references the natural anatomy of patients to progressively advance the needle to target. With the TSMP developed by the coauthors, it is possible to introduce the needle more safely and gain easy access to the herniated disc. Material and Methods: TSMP is a three-step maneuver that builds on the concept of needle puncture site and trajectory determination based on the principles of Kambin’s triangle. First, accurate direction of the puncture is confirmed by inserting the needle horizontally. Then by gradually raising the needle tail in the manner described, the superior articular facet and the intervertebral foramen are sequentially located. Finally, the needle tip slides into the intervertebral foramen to reach the target superior articular facet. We performed a retrospective review of 30 patients who underwent PTED using TSMP for lumbar disc herniation (LDH) and met inclusion criteria from January 2018 to September 2018. The primary outcome, leg or back pain, was assessed using Visual Analogue Scale (VAS). Patient surgical satisfaction was measured at 12 months post surgery using a five-point Likert scale. Potential prognostic factors measured were demographic characteristics, duration of symptom (DOS), and involved levels. Statistical analysis was performed using Fisher exact test and t-test. Results: Preoperative mean VAS was 7.6 ± 1.19, which decreased to 1.4 ± 0.97 at12 months following treatment (P < .0001). Rates of surgical satisfaction per Likert scale were as follows: very satisfied and satisfied in 26 patients (86.7%). According to the subgroup analysis, there were significantly different VAS scores at 12 months postoperatively between the L4-L5 group and the L5-S1 group (P < .01). There were no significant influences at 12 months after PTED on the primary outcome from other factors, including gender, age, body mass index (BMI), and DOS. Conclusion: TSMP is a stable surgical technique for inserting the needle into the intervertebral foramen. Patients who underwent PTED using TSMP fared significantly better with regard to leg and back pain at 12 months after surgery. Given these potential advantages, more research is needed to confirm the efficacy and safety of PTED using TSMP.

Keywords

percutaneous transforaminal endoscopic discectomy, lumbar disc herniation, three-step maneuver for puncture, Kambin’s triangle, visual analogue scale.

713

P403: Minimal Damage, Maximal Result - Treatment of Thoracolumbar Fractures With Minimally Invasive Surgery Using O-arm in Patients With Ankylosing Spondylitis (AS)

David Thorell ¹ , Tobias Kyrk ¹ , and Lukas Bobinski ¹

¹ Umeå University, Department of Surgical and Perioperative Sciences, Umeå, Sweden

Introduction: Ankylosing spondylitis (AS) is a chronic disease with primary involvement of the sacroiliac joints and the spinal column. Patients with AS are highly susceptible to spinal fractures. These fractures tend to be highly unstable with a major risk of medical and neurological complications. The purpose of this study was to compare the clinical results of image-guided surgical treatment of thoracolumbar fractures using minimally invasive surgery (MIS) vs traditional open spine surgery. Material and Methods: This is a preliminary, single-center, retrospective cohort study that enrolled 39 patients with AS (36 men and 3 women), mean age of 70 (range 37-89). All patients were operated at the Spine Unit, Department of Orthopedics, Umeå University Hospital in Sweden, between May 2014 and March 2019, with a long posterior stabilization due to unstable thoracolumbar fractures. The investigated cohort enrolled 23 patients operated with MIS technique. The remaining 16 were operated with traditional open surgery (control group). Image-guided technology (O-arm^®) was used in all surgeries except for 3 surgeries in the Open group, where the 2D C-arm was used. The data included neurological deficits, perioperative bleeding, operation time, hospitalization time, complications, comorbidities, as well as follow-up computed tomography (CT) images to evaluate bone fusion. Results: Patients in the MIS group had significantly shorter mean operation time (154 minutes vs 214 minutes, P = .005) and lesser mean perioperative blood loss (182 ml vs 852 ml, P = .002). Both groups suffered from a high rate of postoperative complications. Tendencies towards fewer complications in the MIS group could be seen, although, the difference was not statistically significant (minor complications 56.5 % vs 73.3 %, P = .294, major complications 21.7 % vs 33.3 %, P = .428). Neurological deficit was recorded in 5 patients before surgery (13.5 %). 2 out of these 5 patients (40.0 %), both in the MIS-group, recovered after surgery without any permanent neurological deficits. No neurologic complication was due to screw misplacement. The rate of revision due to deep wound infection was similar between the two groups (13.0 % vs 13.3 %, P = .979). Tendencies towards quicker mean postoperative mobilization (1682 minutes vs 2574 minutes P = .191) and shorter mean hospitalization time (16.3 days vs 27.8 days, P = .229) could be seen in the MIS group, although these results were not statistically significant. There was no significant difference in fusion rate on postoperative CT-images between the two groups. The multivariate logistical regression analysis showed a significant correlation between time from trauma to surgery and postoperative complications. Longer time increased the risk of minor and overall complications (P = .032). Conclusion: Treatment of thoracolumbar fracture in AS remains a challenging task. Our results indicate that patients with unstable fractures due to AS require rapid surgical treatment to prevent complications. Our results also suggest that MIS technique can provide a valid surgical alternative with a lesser perioperative surgical trauma and faster operation time without affecting the fusion rate of the fractures. MIS-technique should, therefore, be considered as an alternative to traditional open posterior stabilization. However, further validation by larger, prospective randomized trials is desirable.

760

P404: Does the Predominant Pain Location Predict Postoperative Outcomes Following Minimally Invasive Transforaminal Lumbar Interbody Fusion?

Graham Goh ¹ and Reuben Soh ¹

¹ Singapore General Hospital, Singapore, Singapore

Introduction: Surgeons often base decisions on the traditional belief that the predominance of radicular lower extremity symptoms is a stronger indication for lumbar spine surgery than axial pain. However, there is a paucity of literature supporting this notion. This study aimed to determine how different combinations of preoperative back pain (BP) and leg pain (LP) influence functional outcomes, patient satisfaction and return to work in patients undergoing Minimally Invasive Transforaminal Lumbar Interbody Fusion (MIS TLIF) for degenerative spondylolisthesis. Materials and Methods: Patients undergoing a primary, one- to two-level MIS TLIF were retrospectively reviewed and stratified into three cohorts based on predominant pain location: LP predominant ([LPP]; LP>BP), BP predominant ([BPP]; BP>LP) and equal pain predominance ([EPP]; BP = LP). Demographic and perioperative characteristics were recorded. Differences in PROs, including Oswestry Disability Index (ODI), 36-Item Short-Form Physical Component Score (SF-36 PCS), Mental Component Score (SF-36 MCS), Visual Analogue Scale (VAS) for BP and LP, at each postoperative time point were compared using general linear models adjusting for age, gender, body mass index, number of levels, comorbidities and baseline scores. Achievement of minimum clinically important difference (MCID), patient satisfaction assessed using the North American Spine Society (NASS) questionnaire, and return to work were compared using Chi-squared analysis. Results: In total, 781 patients were included: 261 LPP, 224 BPP and 296 EPP. The BPP group was significantly younger, whereas EPP group had a higher proportion of women and diabetics. There were more two-level fusions in the BPP group; LPP patients had the best baseline ODI and SF-36 PCS. With the exception of poorer 1-month ODI in the BPP group (P = .010), both univariate and multivariate adjusted analyses showed no difference in VAS-BP, VAS-LP, ODI, SF-36 PCS and SF-36 MCS among the groups. All three cohorts had similar rates of MCID achievement for ODI and SF-36 PCS. At 2 years, 85%, 87% and 88% in the LPP, BPP and EPP groups were satisfied with treatment, respectively (P = .643), while 98%, 97% and 96% returned to work (P = .745). Conclusion: Patients with degenerative spondylolisthesis undergoing MIS TLIF had comparable pain, disability and quality of life, regardless of their preoperative pain location. A similar proportion of patients achieved a clinically meaningful improvement and were satisfied with surgery.

782

P405: Minimally Invasive Transforaminal Versus Lateral Lumbar Interbody Fusion in Patients With Degenerative Spondylolisthesis: A Propensity Score Matched Study

Graham Goh ¹ and Reuben Soh ¹

¹ Singapore General Hospital, Singapore, Singapore

Introduction: Minimally invasive surgery (MIS) techniques for lumbar fusion have been shown to yield good surgical results. However, few studies have directly compared the clinical efficacy of direct and indirect decompression using transforaminal lumbar interbody fusion (TLIF) and lateral lumbar interbody fusion (LLIF), respectively. This study aimed to compare the patient-reported outcomes (PROs) and satisfaction rates following MIS TLIF and LLIF. Materials and Methods: Patients who underwent a primary, one- to two-level MIS lumbar fusion for degenerative spondylolisthesis were retrospectively reviewed and stratified into two cohorts: TLIF and LLIF. The cohorts were matched in a 1:1 ratio for age, sex, body mass index, comorbidity burden, number of levels fused and preoperative PROs using propensity scoring. Operative time and length of stay were recorded. Differences in PROs, including Oswestry Disability Index (ODI), 36-Item Short-Form Physical Component Score (SF-36 PCS), Mental Component Score (SF-36 MCS), Visual Analogue Scale (VAS) back pain, and VAS leg pain, at each postoperative timepoint (1, 3, 6, 24 months) were compared between the cohorts using independent sample t-tests. Patient satisfaction was assessed using the North American Spine Society questionnaire and compared using Chi-square analysis. Results: In total, 116 patients were included: 58 MIS TLIF and 58 LLIF. The two cohorts were closely matched in terms of demographics, perioperative variables and preoperative PROs. Operative time (TLIF: 205.1 ± 64.3 min vs LLIF: 197.2 ± 90.6 min, P = .626) and length of stay (TLIF: 4.1 ± 2.5 days vs LLIF: 4.4 ± 1.5 days, P = .500) were similar. There was no difference in any PRO at 1, 3, 6 or 24 months. At 2 years, 83% of patients in each group were satisfied with treatment results (P = 956), while 76% and 80% in the TLIF and XLIF groups had expectations fulfilled, respectively (P = .688). Conclusion: Patients with low grade degenerative spondylolisthesis who underwent MIS TLIF and LLIF had similar clinical outcomes of pain, disability and quality of life. Patient satisfaction and expectation fulfilment were also comparable at 2 years.

785

P406: Management of Large Intrathoracic Meningocele: A Case Report

Mohamed Badri ¹ , Mourad Masmoudi ¹ , Kais Maamri ² , Ghassen Gader ¹ , Mouna Rkhami ¹ , Kamel Bahri ¹ , and Ihsen Zammel ¹

¹ El Manar-Tunis university, Faculty of Medicine of Tunis, Department of Neurosurgery, Burns and Trauma Center, Ben Arous, Tunisia

² Fattouma Bourguiba University Hospital, Department of Neurosurgery, Monastir, Tunisia

Introduction: Intrathoracic meningocele is a saccular protrusion of the meninges through a dilated intervertebral foramen or a bony defect of the vertebral column. Kyphoscoliotic deformity of the thoracic spine is often associated. Giant intrathoracic meningoceles associated with neurofibromatosis are rare, and the standard treatment remains controversial. Materials and Methods: We report the case of large Intrathoracic meningocele successfully treated by cysto-peritoneal shunt. Results: A 23-year-old female with no medical history showing clinical features of neurofibromatosis type I with a thoracic kyphoscoliosis. Chest X-Ray showed a giant latero-mediastinal rounded mass. Major complaint of the patient was backpain, intercostal radiculopathy and dyspnea. Spinal and thoracic MRI showed a giant intrathoracic meningocele. The patient underwent surgery. A cysto-peritoneal shunt was placed. The clinical and radiologic follow-up was of 24 months. The patient remain asymptomatic with a satisfying radiologic diminution of the size of the meningocele. Conclusion: Intra-thoracic meningocele is a rare and benign pathology, although surgical treatment is sometimes needed for symptomatic, growing lesions. The surgical approach may be different but challenging for each case.

830

P407: Uruguayan Experience in Tubular Discectomy

Fernando Nin ¹

¹ Medica Uruguaya, Montevideo, Montevideo, Uruguay

Introduction: The MISS technique of tubular discectomy has proven to be one of the main surgical techniques for herniated discs today. With minimal soft tissue injury and rapid recovery from pain and function with low complication rate. Like any surgical technique, its learning curve is essential to achieve optimal results. The objective is to report the experience and analyze the results of the first 30 patients operated with tubular technique in Uruguay. Material and Methods: We retrospectively analyzed all the patients operated from March 2018 to October 2019 (19 months) for lumbar discectomy with tubular systems, for symptomatic disc herniation in two Hospital centers in Uruguay. Patronymic data, level of injury, side, length of stay, complications and readmission rate were analyzed. Pain and function was assessed according to the VAS and ODI scale. Results: We performed 30 MISS tubular discectomy. The mean age was 38.9 ± 7.3 years. Of which 19 male and 11 female. Regarding the lesional level, 15 were L5-S1, 13 were L4-L5 and 2 were L3-L4. The side were 14 right and 16 left. The average hospitalization time was: 36 ± 8.5 hours. Concerning the assessment of pain VAS, it was 8 preoperative and 2 postoperative, and the preoperative ODI was 53 and 17 postoperative. The complications were 3 dural sac injuries. One of them required a reoperation with good subsequent evolution. No patient presented infection of the operative wound. Conclusion: The tubular technique like any surgical technique requires a learning curve. MISS has advantages in terms of incision size, minimally muscle and soft tissue trauma, less bleeding, and a lower rate of infection. The first experience of tubular MISS in Uruguay is consistent with the available evidence, having short hospitalization times, good results in pain relief and functionality with a low rate of complications.

885

P408: Metrics development for minimal invasive unilateral laminotomy for bilateral decompression (ULBD) of lumbar spinal stenosis with or without spondylolisthesis

Carolin Melcher ¹ , Andreas Korge ² , Michael Cunningham ³ , Kevin Foley ⁴ , and Roger Härtl ⁵

¹ University Hospital Ulm, Department of Orthopedic Surgery (RKU), Ulm, Germany

² Schoen Klinik Harlaching, Wirbelsäulenzentrum, München, Germany

³ AO Foundation, Clinical Investigation and Documentation (AOCID), Duebendorf, Switzerland

⁴ University of Tennessee, Semmes-Murphey Neurologic and Spine Institute, Memphis, USA

⁵ Weill Cornell Medical College, New York Presbyterian Hospital, Center for Comprehensive Spine Care, New York, USA

Introduction: Surgical training, on both trainee and master levels, intends to enable a surgeon to acquire the theoretical and practical knowledge necessary to perform a designated surgical procedure skillfully, reliably, and safely. As surgical techniques often defer from surgeon to surgeon and hospital to hospital we aimed to develop, operationally define, and seek consensus from procedure experts on the metrics that best characterize a reference approach to the performance of a minimally invasive unilateral laminotomy for bilateral decompression (ULBD) for lumbar spinal stenosis. Material and Methods: A Metrics Group consisting of three experienced spine surgeons (two neurosurgeons, one orthopedic surgeon), each with over 25 years of clinical practice, and an educational expert formed the Metrics Group that characterized a lumbar decompression surgery for spinal stenosis as a “reference” procedure. In a modified Delphi panel 26 spine surgeons from 14 countries critiqued these metrics and their operational definitions before reaching consensus. Results: Performance metrics consisting of 6 Phases with 42 Steps, 21 errors, and 17 Sentinel errors were identified that characterize the procedure. During the peer review, these were evaluated, modified, and agreed. Conclusion: Surgical procedures can be broken down into elemental tasks necessary for the safe and effective completion of a reference approach to a specified surgical procedure. Spinal experts from 16 countries reached consensus on performance metrics for the procedure. This metric-based characterization can be used in a training curriculum and also for assessment of training and performance in clinical practice.

892

P409: Long Term Pain-Related Outcome Of Minimally Invasive Spinal Decompression vs Laminectomy and Fusion for Stenosis: A Comparative Study

Gilad Regev ^{1, 2} , Morsi Khashan ¹ , Dror Ofir ¹ , Khalil Salame ^{1, 2} , Uri Hochberg ¹ , Gil Leor ² , and Zvi Lidar ^{1, 2}

¹ Tel-Aviv Sourasky Medical Center, The Department of Neurosurgery, Tel Aviv, Israel

² Tel Aviv University, Sackler Faculty of Medicine, Tel Aviv, Israel

Introduction: The long-term pain outcomes and the prevalence of post-operative pain treatments following spinal surgery for degenerative spinal stenosis is still not clear. The purpose of this study is to compare the long-term pain outcomes following minimally invasive spinal (MIS) decompression and open laminectomy with fusion for lumbar stenosis focusing on pain characteristics and its management. Materials and Methods: The study cohort included 95 patients with minimum 5-year postoperative follow-up. Of these, 50 patients underwent unilateral approach bilateral MIS decompression and 45 patients underwent open laminectomy with fusion. Outcome measures included: back and leg pain intensity levels, pain frequency and chronic pain management. Results: The mean age was 69.9 ± 11.7 years in the MIS decompression group and 63.6 ± 13 years in the fusion group. The average follow-up period was 6.2 ± 1.6 years. In the fusion group higher percentage of patients experienced moderate to severe back pain, 48% compared to 21.8% of patients in the MIS decompression group (P < .01). In contrast, we found no significant differences in reported leg pain in both groups. In the MIS decompression group, 43.5% of patients reported moderate to severe leg pain compared to 52% in the fusion group (P = .2). In the fusion group, 20% of the patients described their back and leg pain as constant pain throughout the day compared to only 2.2% in the MIS decompression group (P < .05). A trend towards higher chronic dependence on analgesic medication and repetitive pain clinic treatments was found in the fusion group. Conclusions: Our results demonstrate that MIS decompression resulted in decreased long-term back pain and similar leg pain scores as open laminectomy and instrumented fusion surgery. A trend toward higher dependence on analgesic medication and repetitive pain clinic treatments were found in the fusion group.

898

P410: Dose Tobacco Smoking Affect The Post-Operative Outcome of MIS Lumbar Decompression Surgery?

Dror Ofir ¹ , Morsi Khashan ¹ , Khalil Salame ¹ , Gilad Regev ¹ , and Zvi Lidar ¹

¹ Tel-Aviv Sourasky Medical Center, Neurosurgery, Tel-Aviv, Israel

Introduction: Minimally invasive (MIS) decompression for the treatment of spinal stenosis or disk herniation is often indicated if conservative management fails. Previous studies demonstrated a significant negative impact of smoking on spinal surgeries’ outcome. However the influence of smoking on MIS spinal decompression is yet to be established. Therefore, we sought to compare clinical outcome post-operative complication following MIS decompression smoking patients and non-smoking patients.Material and Methods: We evaluated medical records of 132 consecutive patients who underwent minimally invasive lumbar decompression between November 2013 and July 2017 at our institute. The data was collected prospectively to our data base, the study (S) group included 36 smoking patients and the control (N) group comprised 96 nonsmoking patients. Medical history, American Society of Anesthesiologists ASA score, perioperative mortality, complications, and revision surgery rates were collected and analyzed. The Oswestry Disability Index (ODI) was used to evaluate functional outcome. Results: The two groups were comparable in terms of demographic and preoperative variables. No significant difference was found in rated of post-operative complications and revision surgeries between the groups. Both groups showed significant improvement in their ODI scores at 12 and 24 months following surgery. Conclusions: Our results indicate in patients undergoing MIS lumbar decompression smoking may not be a significant risk factor for post-operative complications or poorer clinical outcome.

907

P411: Minimally Invasive Discectomy Versus Open Laminectomy and Discectomy for the Treatment of Cauda Equina Syndrome: A Case Control Study

Gilad Regev ^{1, 2} , Alon Grundshtein ¹ , Morsi Khashan ¹ , Dror Ofir ¹ , Khalil Salame ^{1, 2} , and Zvi Lidar ^{1, 2}

¹ Tel-Aviv Sourasky Medical Center, The Department of Neurosurgery, Tel Aviv, Israel

² Tel Aviv University, Sackler Faculty of Medicine, Tel Aviv, Israel

Introduction: Cauda Equina syndrome (CES) is a potentially devastating condition and is treated usually with urgent open surgical decompression of the spinal canal. Currently, the role of minimally invasive discectomy (MID) as an alternative surgical technique for CES is unclear. The objective of this study is to compare the outcomes following MID and open surgery for CES. Methods: The clinical and radiological presentation, surgical data and outcomes of patients who underwent surgery for CES were reviewed. Final outcomes were collected by telephone interview and included postoperative neurological deficits, Numerical Rating Scale (NRS) for leg and back pain, Oswestry disability index (ODI), and the EQ-5D health-related quality of life questionnaire. Results: Twelve patients underwent MID and 11 underwent open laminectomy and discectomy. Mean follow up time was 55 months for the open group and 40 months for the MID group (P = .4). No significant differences were found in the preoperative clinical presentation, neurological deficits or radiological assessment. The rates of complications and revisions were also comparable between the groups. The MID group reported lower rates of residual lower limb weakness in the final follow-up (41.7% vs 90%, P = .03). Postoperative NRS improved from 7.4 to 2.3 for leg (P = .004) and from 6.8 to 3.2 for back pain (P = .01) in the MID group. In the open group pain NRS improved from 7.8 to 4.5 for leg (P = .84) and from 7.4 to 5.1 for back pain (P = .21). However, final pain scores were not statistically different between the groups. Conclusions: Minimally invasive discectomy for the treatment of CES resulting from lumbar disc herniation was found to be an effective and safe procedure when compared to open laminectomy and discectomy.

1006

P412: Economic Performance on Trans-Kambin Posterior Oblique Lateral Lumbar Interbody Fusion (OLLIF) With a Focus on Hospital Throughput Efficiency

Hamid Abbasi ¹

¹ Inspired Spine, Neurosurgeon, Burnsville, USA

Introduction: Between 1998 and 2008 the number of spinal fusions in the U.S. increased 2.4 fold and the cost per fusion increased 3.3 fold, leading to a 7.9 fold increase in the cost burden of spinal fusions to the U.S. health care system. OLLIF is a new minimally invasive procedure for fusions of the Lumbar spine that can be employed safely and effectively from T12-L1 to L5- S1. OLLIF approaches the disk space through Kambin's triangle. OLLIF does not requiring direct visualization but instead relies on bilateral fluoroscopic imaging and electrophysiological monitoring. OLLIF reduces surgery times and hospital stay compared to TLIF. The purpose of this study is to evaluate the preoperative cost of OLLIF compared to TLIF. Material and Methods: The study population are 69 OLLIF patients and 58 open TLIF controls. All patients underwent full course of conservative therapy. Indications were Degenerative Disk Disease, Disk Herniation, Listhesis, Stenosis (except Osteogenic Stenosis). This is a retrospective cohort study. All surgeries were single surgeon procedures and all TLIF cases were completed before the surgeon started performing OLLIF. We recorded surgery time, length of stay and infection rates. Perioperative outcomes were monetized by using a multiplier approach. OR Time was monetized at $ 83.51/minute and hospital stay at $ 2197/day. Infection rate was monetized relative to a 2.4% infection rate for open procedures. Results: OLLIF cuts surgery times and hospital stay in half relative to TLIF (59/132 min, 4.7/2.3 days respectively). When these differences are monetized, OLLIF reduces the average cost per surgery relative to TLIF by $11,834 per surgery, with higher cost reductions for multi-level procedures. In over 500 OLLIF procedures to date, there have been no deep infections requiring drainage and only a single superficial infection (0.2%). We estimate that the reduction in infections saves an additional $316 per surgery, for a total cost reduction of $12,150. Conclusion: OLLIF is a new MIS spinal fusion that reduces perioperative costs relative to open surgery and could potentially reduce U.S. healthcare expenditures by $2.5bn per year, through the preoperative cost savings alone. A comprehensive cost analysis is under way.

1011

P413: Effect of Body Mass Index on Perioperative Outcomes in Minimally Invasive Trans-Kambin Posterior Oblique Lateral Interbody Fusion Versus Open Fusions: A Multivariant Analysis

Hamid Abbasi ¹

¹ Inspired Spine, Neurosurgeon, Burnsville, USA

Introduction: Obesity is an increasing public health concern associated with increased perioperative complications and expense in lumbar spine fusions. While open and mini-open fusions such as transforaminal lumbar interbody fusion (TLIF) and minimally invasive TLIF (MIS-TLIF) are more challenging in obese patients, new MIS procedures like oblique lateral lumbar interbody fusion (OLLIF) may improve perioperative outcomes in obese patients relative to TLIF and MIS-TLIF. Material and Methods: Patient sample We included patients who underwent OLLIF, MIS-TLIF, or TLIF on three or fewer spinal levels at a single Minnesota hospital after conservative therapy had failed. Indications included in this study were degenerative disc disease, spondylolisthesis, spondylosis, herniation, stenosis, and scoliosis. Outcome measures We measured demographic information, body mass index (BMI), surgery time, blood loss, and hospital stay. Methods We performed summary statistics to compare perioperative outcomes in MIS-TLIF, OLLIF, and TLIF. We performed multivariate regression to determine the effects of BMI on perioperative outcomes controlling for demographics and number of levels on which were operated. Results: OLLIF significantly reduces surgery time, blood loss, and hospital stay compared to MIS-TLIF, and TLIF for all levels. MIS-TLIF and TLIF do not differ significantly except for a slight reduction in hospital stay for two-level procedures. On multivariate analysis, a one-point increase in BMI increased surgery time by .56 ± .47 minutes (P = .24) in the OLLIF group, by 2.8 ± 1.43 minutes (P = .06) in the MIS-TLIF group, and by 1.7 ± .43 minutes (P < .001) in the TLIF group. BMI has positive effects on blood loss for TLIF (P < .001) but not for OLLIF (P = .68) or MIS-TLIF (P = .67). BMI does not have significant effects on length of hospital stay for any procedure. Conclusion: Obesity is associated with increased surgery time and blood loss in TLIF and with increased surgery time in MIS-TLIF. Increased surgery time may be associated with increased perioperative complications and cost. In OLLIF, BMI does not affect perioperative outcomes. Therefore, OLLIF may reduce the disparity in outcomes and cost between obese and non-obese patients.

1012

P414: Clinical and Radiological Outcomes of Trans-Kambin Posterior Oblique Lateral Lumbar Interbody Fusion

hamid abbasi ¹

¹ Inspired Spine, Neurosurgeon, Burnsville, USA

Introduction: Oblique lateral lumbar interbody fusion (OLLIF) is a novel operation for fusions of the lumbar spine from T12–S1. In OLLIF, the disk is approached from an oblique lateral angle guided by electrophysiological monitoring and biplanar fluoroscopy; the disk space is accessed through Kambin’s triangle. Material and Methods: For a single-level OLLIF, mean surgery time was 56.6 ± 37.7 minutes, with a blood loss of 42.2 ± 31.1 mL, fluoroscopy time of 198.8 ± 87.2 seconds and a hospital stay of 2.2 ± 1.7 days. At the 1-year follow-up, 10-point pain scale scores improved from 8.6 ± 1.3 to 4.1 ± 3.0 (p &lt; .001). Total Oswestry disability index score improved from 56.6% ± 15.3% to 38.6% ± 21.4% (p &lt; .001). Results: At the 1-year follow-up, 15 (5%) patients had mild nerve root irritation defined as sensory symptoms and motor weakness better than 4/5. Only 1 patient had neuropraxia due to weakness (3/5). There was 1 case (0.3%) of superficial wound infection and 1 case of bleeding into the psoas major. Reoperation within 1 year was performed for 14 (4.7%) patients. Interbody fusion was achieved in 98.7% of levels. Conclusion: While OLLIF has previously been described, this study is the first to present clinical, patient-reported, and radiological outcomes of OLLIF. Review of the literature shows that OLLIF produces perioperative outcomes, complication rates, and fusion rates that compare favorably with similar procedures. We establish that OLLIF is a safe, efficient and efficacious procedure for fusions of the lumbar spine.

1039

P415: Endoscopic Sacro-Iliac Joint (SIJ) denervation treatment. A single center experience

Pierluigi Granaroli ¹ , Carlo Conti ¹ , and Melina Castiglione ¹

¹ Santa Maria Hospital, Neurosurgery, Terni, Italy

Introduction: Low back pain is a common health problem with a high frequency of functional disability. The dysfunction of the sacroiliac joint (SIJ) complex is one of the most frequent cause of chronic low back pain (CLBP), accounting for 10–33% of cases reported in the literature. The radiofrequency denervation is an effective minimally invasive treatment for CLBP. However, few clinical retrospective studies have been published on this topic and even less revealed a real effectiveness on pain relief. The endoscopic radiofrequency denervation is a novel technology that allow, with a direct visual control and high magnification, to visualize the Sacro-Iliac joints and perform the ablation with higher precision. Material and Methods: Forty-four consecutive patients with CLBP underwent radiofrequency ablation (RFA) of the SIJ between July 2019 and August 2020. Patients enrolled in this study complained of more than 6 months of drug resistant low back pain. Twelve patients (27,2%) underwent previous surgery or other invasive procedure for pain relief. The criteria of diagnosis were clinical examination and computed tomography (CT) scan. Results: All patients underwent a diagnostic block with an intra-articular injection of steroid and local anesthetics. Only patients with a 50% of pain relief on the visual analogic scale (VAS) and the Oswestry disability index (ODI) underwent the Endoscopic Radiofrequency denervation of the SIJ. The ablation of the posterior capsule of the SIJ and the lateral roots of L5, S1, S2, S3 was made using a monopolar radiofrequency probe located close to the target by the endoscope. The mean operative time was 20 to 50 minutes. VAS and ODI scores, for pain and disability evaluations, were performed preoperatively, at one day after surgery, and at one, three, and six months during the outpatient clinic visits. The mean VAS and the ODI scores decreased significantly after the procedure in 95% of patients and kept significantly lower than baseline levels during the follow-up in 89% of patients. No complications occurred during surgery and follow-up. A mean of 90% of patients were satisfied of the procedure. Conclusions: The Endoscopic Radiofrequency denervation of the SIJ is a tolerated and promising minimally invasive option for drug resistant low back pain in selected patients with good response to diagnostic block. In the short term this technique shows an excellent result in term of pain relief and functional ability. However, longer follow-up is necessary to confirm if this procedure is more effective than percutaneous radiofrequency denervation.

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P416: Intraoperative Triggered Electromyography for Improving the Accuracy and Safety of Minimally Invasive Percutaneous Lumbosacral Screw Placement

Pablo Mendivil ¹

¹ Unidad de Cirugía Espinal Compleja y Minimamente Invasiva - Neurocentro Salta - IMAC Instituto Medico de Alta Complejidad, Salta Argentina, Departamento de Neurocirugía, Salta, Argentina

Background: Because the increase of minimally invasive fusion technics with percutaneous screw placement, intraoperative neurophysiological monitoring become an important topic in spine surgery in order to achieve appropiated accuracy and avoid surgical misplacement complications. In clinical practice the amplitudes vary between the stimulation of the Jamshidi needle and Kirschner wire, and the pedicle screw. Materials and Methods: A prospective study was performed to evaluate the effectiveness of triggered electromyography in predicting pedicle screw misplacement and subsequent lumbar radiculopathy. We use our intraoperative t-EMG criteria for percutaneous screw placement (Glassman modified criteria) 11 mAh or less not acceptable, 12 -13 mAh acceptable if surgeon and assistant agree and intraoperative Rx fulfill certain requirements, 14 mAh or more acceptable. 61 patients (268 screws) were able to follow up; new onset of postoperative radiculopathy and the accuracy of the screw with the Heary tomography scale were recorded. Electrically evoked electromyography threshold for the Jamshidi needle, Kirschner wire and pedicle screws were also recorder. Results: The mean age was 54.5 years, and 268 screws were implanted under controlled homogeneous conditions (TIVA, BIS 45-55) with 19 pedicle breaches grade II (5), III (11) and IV (3) in the Heary tomography scale (7 %) but without clinical consequences or therapeutic relevance. AVERAGE T-EMG was Yamshidi 21.4 mAh, Kirshner 24.5 mAh and Screw 25,6 mAh. No revision surgeries were required because pedicle screws position. New onset of radicular pain or neurological deficit was recorder in 8. An average of 4,2 milliamps difference (Range from 2 to 9) were recorder between the stimulation of Kirschner needle and definitive screw. Position of 36 needles was changed because of critical intraoperative stimulations results. Conclusions: Pedicle screw malpositioning is very common, with rates reported in the literature ranging from 3 to 55 %. Reoperation rate owing to screw malposition from 8.8% in conventional surgery to 2.9% in navigated surgery. We evaluate the therapeutic implications of the difference between stimulation of the Jamshidi needle, Kirschner wire and pedicle screws, in the decision to modify the situation of the pedicle needle or proceed to the placement of the screw by Borderline amplitudes. Clinical outcome and reoperation rate is better under INM and fluoroscopy compared with published data of fluoroscopy alone or navigation, although accuracy is better wit navigation. We support the routine use and utility of neuromonitoring techniques for improving the accuracy and safety of pedicle screw implantation using the Glassman modified criteria.

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P417: To Describe Technique and Effectiveness of Percutaneous Screw Insertion with Microscopic Fenestration Approach for Reduction of High Grade Listhesis

Jayesh Pawar ¹ , Dr Mihir Bapat ¹ , and Arpit Upadhyay ¹

¹ Nanavati Hospital, Spine, Mumbai, India

Introduction: The Surgical treatment of HGS has dilemma wavers between in-situ fusions versus reduction. A slip reduction restores spino-pelvic parameters and improves contact surface for fusion. Conventional open reduction is standard surgical treatment. The authors wish to propose a technique that combines percutaneous screw insertion with microscopic fenestration approach for reduction of HGS. Material and Methods: 17 patients were operated for HGS between 2013 and 2016 and followed prospectively for 2 years. Low grade spondylolisthesis and spondyloptosis were excluded. Demographic and clinical data were recorded. Clinical outcomes were assessed using visual analogue score (VAS) and Modified Oswestry Disability Index (ODI). Spino-pelvic parameters were measured at pre and post-operative. Fusion was assessed using bridwell criteria at final follow up. Multifidus injury was assessed at index and supra-adjacent level on MRI at 1 year follow up. Results: Out of 17(M: F-6:11) patients, 15 had grade-III and 2 had grade-IV isthamic spondylolisthesis. The average age was 49.81(±14.77) years. The surgical level was L5-S1 in 15 and L4-5 (L5-sacralised) in 3 patients. Mean operative surgical time and blood loss were 188(±21.77) minutes and 115(±29.10) millilitres respectively. Mean radiation exposure was 80.9(±25.05) seconds. The average hospital stays were 3.3(±0.92) days. Slip% and slip angle were improved significantly after surgery. Complete reduction achieved in 10 and 7 reduced to grade-I. 5 patients in unbalanced group switched in balance, while 12 remained in balanced after correction. 13 had grade-1(complete) where as in 4 had grade-2 fusions. Two had postoperative neuropraxia, which recovered at 3 months. A multifidus atrophy increased by one grade at operative level, while it remained unchanged at supra-adjacent level. Conclusion: The current technique proved an effective in reducing of slip% and restoring spino-pelvic parameters and lumbosacral lordosis. The long term clinic-radiological outcomes were favorable. It had lesser operative time, blood loss and hospital stays than conventional posterior approach.

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P418: Comparison of Outcomes in Percutaneous Fixation of Traumatic Fractures Between Ankylosing Spondylosis and Diffuse Idiopathic Skeletal Hyperostosis

Scott McCarty ¹ , Jacob Bruckner ¹ , Jael Camacho ¹ , Daniel Cavanaugh ¹ , Eugene Koh ¹ , Daniel Gelb ¹ , and Steven Ludwig ¹

¹ University of Maryland School of Medicine, Department of Orthopaedics, Baltimore, USA

Introduction: The management of trauma in patients with ankylosing spondylitis (AS) and diffuse idiopathic skeletal hyperostosis (DISH) presents a unique challenge due to the instability and neurologic compromise that can occur following relatively minor trauma. Many of these patients require surgical stabilization of their injuries. Prior literature has supported the use of using minimally invasive surgical techniques for stabilization in patients with ankylosed spines and have shown similar outcomes to traditional open surgery. Material and Methods: Following IRB approval, the operative logs from 2012-2019 of four fellowship trained spine surgeons from one academic, Level I trauma center was reviewed for cases of thoracic and lumbar spinal fractures in patients with AS, DISH, or unclassified ankylosing spinal disorders that were treated with a minimally invasive surgical approach. Outcomes measures were complication rates, estimated blood loss, operative time, and need for transfusion. Variables were compared between patients with AS, DISH, and spontaneous ankylosis. Statistical analysis for continuous variables was performed using an independent t-test and chi-square test for nominal variables. Normality was assessed using Shapiro-Wilk test and significance level was set at α = .05. Results: A total of 48 patients with a thoracic or lumbar spinal fracture that were treated with a MIS approach and an ankylosing spinal condition were identified, of which 35 (72.9%) were male. 11 patients were identified with AS, 20 with DISH, and 15 with spontaneous ankylosis. Patients who experienced other body trauma approached significance in DISH and spontaneous ankylosis patients, with 17 (81.0%) and 12 (75.0%), respectively. Complications differed between groups, with a total of 27 (56.3%) patients experiencing complications. DISH patients were more likely to have a post-operative complication than AS patients (P = .0238). There was no significant difference in length of surgery, estimated blood loss, length of stay, readmission, and reoperation rates amongst AS and DISH patients. There were 3 mortalities unrelated to the surgical procedure. Conclusion: Percutaneous stabilization of patients with ankylosing spinal disorder fractures remains a viable management method. Operative characteristics are similar between AS and DISH, however there was a much larger complication profile seen in DISH patients and they were statistically more likely to experience a post-operative complication.

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P419: Robot-Assisted Spine Surgery: A Report of the First Cases in United Kingdom

Gustavo Carrico ¹ , Khai Lam ¹ , and Carlos De La Torre ¹

¹ London Bridge Hospital, Spine Surgery, London, United Kingdom

Introduction: Minimally invasive antero-lateral and lateral lumbar interbody fusion are retroperitoneal approaches that allow the placement of a larger interbody implant, allowing for a larger fusion area. At the same time, there is a high interest in the emerging field of robot-navigated spine surgery for the posterior screw fixation.This is a single-surgeon, single-site report of the first procedures ever performed for navigated robot-assisted spine surgery in the United Kingdom. Materials and Methods: Between October 2019 and July 2020, we identified 30 consecutive patients who underwent robot-assisted spine surgery. The demographic, intraoperative, and perioperative data of all patients were reviewed. Technique: With the patient positioned in the lateral or dorsal decubitus position, a routine antero-lateral anterior lumbar interbody fusion (AL-ALIF) and/or an extreme lateral interbody fusion (ELIF) is performed. In a second stage, with the patient in a ventral decubitus position, a dynamic reference base and a surveillance marker are put in place, an intraoperative CT scan is obtained from a portable intraoperative CT and the images are transferred into the robotic positioning system. Pedicle screw trajectories are planned and saved. A surgeon-controlled foot pedal will activate and position the robot arm to the planned pedicle trajectory. Stab incisions will be made on the skin using a scalpel. Pedicle screws will be inserted using navigated instruments guided by the robotic arm. This sequence will be repeated until all pedicle screws had been placed. Rods will then be placed in a standard fashion and locking caps will be set once the rods are in their proper position. If needed, one can also insert the pedicle screws using an open or a transmuscular technique or consider performing a single position lateral (SPL) approach with a single stage procedure. Results: Of the 30 patients, 52 levels were treated in total (168 screws), with 2 patients treated with kyphoplasty/vertebroplasty and 1 patient with SI joint fusion. 18 patients (60%) underwent single-level fixation, with 3 of them undergoing a SPL technique, 14 of them (47%) were treated at the L5/S1 level, 2 at L3/L4 and 1 at L4/L5 level, 9 patients (30%) underwent multi-level fixation, with 4 of them treated for adult scoliosis, 21 patients underwent an ALIF approach and 12 an ELIF approach. The average estimated blood loss was 62 cc. The average planning time was 10.7 min and the average duration of surgery was 59 min. The average patient age was 54 years and 63% (19/30) were male. The average BMI was 28.4 kg/m². There were no re-interventions due to complications or mal positioned screws. Conclusion: Minimally invasive spine surgery using robot-assisted navigation has many advantages such as improved accuracy, decreased radiation exposure, minimal muscle disruption, decreased blood loss, shorter operating theatre time, and lower complication rates. Further follow-up of the patients treated will help compare the clinical outcomes with other techniques.

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P420: Experience and Early Results With an Expandable Lateral Interbody Device and Integrated Screw Functionality

Andrew Berg ¹ , Zacharia Silk ¹ , Sandra Bonczek ¹ , Peter Loughenbury ¹ , Rachel Stearn ² , and Jake Timothy ²

¹ Leeds General Infirmary, Leeds, United Kingdom

² Nuffield Health Leeds, Leeds, United Kingdom

Introduction: Fixed ‘hypelordotic’ interbody devices are reported to offer a safe alternative to osteotomy when addressing segmental kyphosis in adult spinal deformity. Endplate injury and consequent subsidence remain problematic. Expandable interbody devices offer a reduced insertion height combined with the ability to modulate disc distraction and segmental lordosis. This may result in less risk of intra-operative endplate injury. We report on the use of a novel expandable lateral lumbar interbody device. Material and Methods: A retrospective review of the radiological and clinical outcomes of five consecutive patients (all female) treated using a titanium expandable interbody spacer device with a novel integrated screw feature (ELSA, Globus Medical Inc., Audubon, PA, USA) was performed. Standard MIS transpsoas approach with intra-operative neuromonitoring. The disc and endplates were prepared, and an appropriately sized cage inserted and expanded to maximise anterior column height and lumbar lordosis. The cage was secured with two divergent corticocancellous screws, providing immediate primary stability. Results: Three single level and two two level procedures were performed. In two patients surgery was above previously fused segments. All patients reported immediate post-operative improvement in back and leg pain VAS scores through indirect decompression. At 6 months follow up there was a mean increase in lumbar lordosis of 5.12 degrees and mean increase in segmental lordosis of 4.98 degrees. No patient required a secondary procedure (i.e. posterior decompression or stabilisation). Conclusion: An expandable lateral lumbar interbody fusion device provides a safe means to achieve indirect decompression and an increase in segmental lordosis. The addition of an integrated screw feature provides immediate primary stability, avoiding the requirement for a second stage posterior stabilisation.

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P421: Are Foraminal Indirect Decompression Outcomes in Degenerative Spondylolisthesis Different From Other Degenerative Lumbar Disease After Minimally Invasive Extreme Lateral Interbody Fusion?

Khai Lam ¹ and Carlos De La Torre ¹

¹ London Bridge Hospital, AOSpine Centre, London, United Kingdom

Introduction and Purpose: Lateral recess and neural foramina stenosis commonly results from degenerative changes such as collapsed or bulging discs and spondylolisthesis. The purpose of this study was to determine which condition benefits more from indirect decompression with the ELIF approach, namely degenerative spondylolisthesis (DS) versus other degenerative disease of the lumbar spine (ODD) (i.e. disc disease, scoliosis, ASD). Materials and Methods: Between January 2013 and January 2020, we identified 139 consecutive patients undergoing ELIF for lumbar pathology. Out of these, PROMS were collected from 67 patients preoperatively and up to 12 months postoperatively. Foraminal area was measured on the preoperative and intraoperative (i.e. after placement of interbody cage) CT scans of all 67 patients using the elliptical ROI tool of the Hospital’s PACS software. PROMS included Oswestry Disability Index (ODI), VAS for both back (BP) and leg pain (LP) and SF-36. Results: There were 56% female and 44% male patients with a mean age of 47 (32-72) years. 31 patients had diagnosis of DS and 36 patients of ODD. In the DS group the mean right foraminal area increment from preoperative to intraoperative was 70.9 ± 16.1 mm² (P < .02) from a mean preoperative of 106.9 ± 26.3 mm²(P < .02), the mean left foraminal increment was 48.3 ± 26.2 mm² (P < .02) from a mean preoperative of 12O.9 ± 25.9 mm² (P < .02). In the ODD group the mean right foraminal increment was 65.2 ± 18.7 mm² (P < .02) from a mean preoperative of 83.0 ± 21.6 mm² (P < .02), the mean left foraminal increment was 38.3 ± 21.5 mm² (P < .02) from a mean preoperative of 117.2 ± 31.8 mm² (P < .02). For ODI, in the DS group, statistically significant mean improvement from pre-operative to last follow-up was 23.2 ± 31.5 points (P < .001), and in the ODD group was 34.2 ± 24.5 points (P < .001). For VAS BP, in the DS group, the mean improvement was 5.4 ± 2.6 points (P < .001) and in the ODD group was 4.2 ± 3.7 points (P < .001). For VAS LP, in the DS group, the mean improvement was 5.3 ± 4.5 points (P < .001), and in the ODD group was 3.7 ± 4.2 points (P < .001). For the PCS domain of SF-36, in the DS group, the mean improvement was 12.8 ± 18.3 points (P < .02), and in the ODD group was 9.6 ± 16.8 points (P < .02). For the MCS in the DS group, the mean improvement was 17.1 ± 13.8 points (P < .02) and in the ODD group was 7.1 ± 12.9 points (P < .02). Conclusions: In ELIF, indirect decompression is realised through placement of large intervertebral spacers that restore and realign lumbar segments and indirectly decompresses neural elements through disc and foraminal height restoration. Comparison between both groups demonstrated similar improvements in both foraminal area restoration and PROMS, although there was a 1 cm² increment difference on the left foramen of the DS group. These results corroborate that indirect decompression in ELIF has shown to be adequate in providing symptom relief in most patients with degenerative spinal conditions.

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P422: Long Term Outcome of Thoracoscope Assisted Anterior Spinal Interbody Fusion and Simultaneous Posterior Instrumentation in Prone Position: Emphasis on Location of Pathology, Fusion Rates and Operative Time

Nirmal Patil ¹ , Mootaz Shousha ¹ , and Heinrich Boehm ¹

¹ Zentralklinik, Spine surgery, Bad Berka, Germany

Introduction: The debate on the value of anterior surgery, in particular in the thoracic and thoracolumbar region has withered in recent times. Supposedly high complication rates of conventional open transthoracic surgery performed under conditions of the 1970´s or 1980´s are repeatedly cited and taken as proof that posterior methods are superior. Thoraco-scope assisted procedures significantly reduce the trauma of approach at the level of the chest wall. Thoracoscopy in prone position has an added advantage of providing simultaneous access to both the spinal columns, obviating the need for repositioning, re-draping or staging the surgery. However, there is still debate if minimal invasive spinal surgeries could impair the fusion rates at the level of the anterior spinal column and increase the operative time. Material and Methods: Operative records of 238 patients (313 levels) operated in a tertiary care centre via thoracoscope assisted interbody fusion surgery and segmental (open) pedicle screw instrumentation performed in prone position in a single stage were reviewed. Only cases with interbody fusion surgeries were included. Operative time for anterior thoracoscopic surgery and posterior exposure and screw insertion were recorded separately. The patients were further divided into groups based on the operated levels and the side of approach. Fusion status at final follow-up was recorded. Results: The diagnosis were Pyogenic Spondylitis (74), Fracture (96), Ankylosing Spondylitis (38) and Degenerative Disease (105). The total operative time (anterior + posterior) was 222.8 ± 91.7 (51-625 mins). Left sided approach dominated the cohort (171 vs 142). Diagnosis had a significant impact on the total as well as thoracoscopic operative time (P =< .01). Degenerative pathologies (thoracic discs) took the longest total (236 ± 77.5 mins) and anterior (108.9 ± 45 mins) operative time while Pyogenic Spondylitis cases finished earlier (177.4 ± 66.2 mins and 66.3 ± 32 mins). This was mainly due to the need for additional thecal sac decompression and removal of the posterior longitudinal ligament. The anatomic levels did not have a significant effect on the operative time in non-degenerative pathologies (P = .062) while it was significant in degenerative pathologies (P =< .01). Although left side took a longer operative time (78.3 mins vs 69.1 mins), no significant difference in the surgical time was found according to the side of approach (P = .08). There was no comparable data for similar pathologies tackled via all posterior approach published in literature. At final follow-up (mean 65.19 months, upto 20 years) 89% of the levels were fused; the optimum fusion state = Grade 0 was detected in 185 levels, solid, but less complete = grade 1 in 53, grade 2 in 40, grade 3 in 24, grade 4 in 0, and grade 5 (failure) in 11. The reason for failures were; Implant failure (4), graft failure (2), pseudoarthrosis (3) infection (1) progressive kyphosis (1). Six out of eleven cases failed with-in one year post surgery and required reoperation. Majority of the revisions encompassed the dorso-lumbar junction (90.9%). Conclusion: Prone thoracoscopy proves to be a valuable component in anterior reconstruction with high rates of fusion, few revisions and has comparable operative time to other established methods of fusion from posterior.

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P423: Modified Midline Lumbar Interbody Fusion (mMIDLIF): Lumbar Decompression and Stabilization Through a Same Size Approach as for Standard Microdiscectomy?

Benedikt Trnovec ^{1, 2} , Peter Hudak ¹ , Milan Liska ¹ , Robert Chrenko ² , Svorad Trnovec ³ , and Kamil Kolejak ¹

¹ University Hospital Bratislava Ruzinov, Neurosurgical department, Bratislava, Slovakia

² National Institute of Children's Diseases, Neurosurgical department, Bratislava, Slovakia

³ University Rostock, Neurosurgery, Rostock, Germany

Introduction: The medio-lateral transpedicular cortical screw trajectory in a MIDLF procedure uses the standard approach for a microsurgical spinal decompression with bilateral lateralization of paravertebral muscles. As in various available reports from smaller patient groups reported retrospectively, this approach has some reasonable benefits compared to PLIF/TLIF procedure: smaller wound, faster mobilization, shorter hospital stay, lower need for postoperative analgesia and probably lower wound healing complications which is crucial in spinal stabilization. Our goal was to render this technique more precisely regarding the invasiveness to the smallest possible way and in general to minimize the relatively higher complication rate well known from standard instrumentations compared to less invasive microsurgery. Material and Methods: Medial Skin incision from 3 cm (1 level) to 6 cm (3 level) was made. Differing from the standard MIDLIF procedure we only use the unilateral microsurgical approach for decompression and cage insertion after complete discectomy, eventually with undercutting. Due to minimal invasive approach, we use percutaneous instrumentarium: screw insertion in the open side can be done without retractor and the contralateral screw placement is performed transfascial without lateralization of the paravertebral muscles. Results: Our initial experience and simultaneously collecting prospective data about modified MIDLIF started in February 2020, since then we operated 10 patients: 7 female and 3 male. Median age was 67. There were 4 patients with 1 level, 5 patients with 2 level and 1 patient with indication for 3 level surgery. We are focusing to involve more patients and on collecting data for long term outcome, our actual cohort is specific due to general covid-19 pandemic restrictions: fewer patients, the most patients had preoperative paresis or were immobile. We had 1 patient with 1 misplaced screw without neurovascular damage but in need for revision and two cases of reparable dural tears without any later complications. Average hospital stay after surgery was 5,33 days. There were no wound healing complications. Postoperative analgetic regime was comparable with patients after standard microdiscectomy. Conclusion: MIDLIF procedure with cortical screw placement is becoming an important micro-invasive alternative to standard TLIF and PLIF procedures. Our experience with modifying this technique shows the possibility of even more invasion reduction.

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P424: A Case Control Study of Minimal Invasive Transforaminal Interbody Fusion (MI-TLIF) Versus Extreme Lateral Interbody Fusion (ELIF) at the L4/L5 level - Clinical Outcomes and Complications

Carlos De La Torre ¹ and Khai Lam ¹

¹ London Bridge Hospital, London, United Kingdom

Introduction: The L4-L5 level has been controversial during past years, especially for its treatment using the Extreme Lateral Interbody Fusion Approach (ELIF) due to the positioning of the lumbar plexus near the area of interest. Material and Methods: This is a case control study of patients who underwent MI-TLIF at the L4/L5 level against patients who underwent ELIF. All patients were followed up using the Oswestry Disability Index (ODI), SF-36 Questionnaire and VAS for pain assessment at 3, 6 and 12 months as well as review of incidence of complications between the 2 techniques. The same surgeon performed all surgeries. Results: A total of 81 single level L4/L5 fusion patients were identified, of which 36 were operated using MI-TLIF and 45 using ELIF, mean age in both groups was 55.83 years, with no statistically significant difference between both groups. The ODI reduction (28.8 TLIF vs 27.8 ELIF), VAS reduction (LBP 3.7; LP 3.9 vs LBP 3.9; LP 3.8) and SF-36 (PCS 8.1; MCS 10.5 vs PCS 7.9; MCS 10.2) data on outcomes at 12 months follow up was not statistically significant either. In terms of complications in the ELIF group, 1 patient presented with L4 radicular pain after surgery that resolved, which was attributed to the surgical access, and in the MI-TLIF group 1 subject presented with a dural tear. In terms of patients requiring revision surgery we also found 1 in the MI-TLIF group and 1 in the ELIF group; the MI-TLIF patient required revision for pseudoarthrosis which resolved with an anterior fusion, and 1 patient ELIF group which required revision contralateral decompression and the symptoms resolved. Conclusion: This case control study shows that in experienced hands the rate of complications from the ELIF approach is minimal and comparable to the MI-TLIF. And that there are no differences in approaching the L4/L5 level either from a MI-TLIF approach or an ELIF approach in terms of disability and pain variations in our 12 months follow-up.

1306

P425: Post-operative Intracranial Subarachnoid Hemorrhage After Full Endoscopic Cervical Spine Decompression - Case Report and Literature Review

Marcos Vaz de Lima ¹ , Antonio Roth Vargas ² , Enrico Ioriatti ³ , and Marco Moscatelli ⁴

¹ Santa Casa De São Paulo, Orthopedics, São Paulo, Brazil

² Centro Médico De Campinas, Campinas, Brazil

³ Endospine Center, São Paulo, Brazil

⁴ Neurolife, Natal, Brazil

Degenerative disease of the cervical spine can develop with severe myelo-radicular syndromes. In cases of intractable pain and or in the presence of neurological deficits, surgical intervention may be necessary. Several surgical techniques are described in its treatment. Recently, posterior decompression using the totally endoscopic route has become an excellent treatment option for cases that evolve with refractory root syndrome. The present article makes a brief review of the literature and reports the case of a 52-year-old female patient with left cervical-brachialgia, associated with C7 root sensory and motor deficit, secondary to C6-7 cervical disc herniation. In the intraoperative time, a small dura mater lesion was observed. In the immediate postoperative period, the patient showed significant improvement in radicular pain, however, he complained of headache and diplopia. On physical examination, she presented paresis of the right lateral rectus muscle, indicating a probable involvement of the abducent nerve. Undergoing a cranial tomography exam that showed extensive subarachnoid hemorrhage, with ventricular flooding and hydrocephalus. Intracranial vascular investigation ruled out the possibility of aneurysms or vascular malformations. Despite the severity of the condition, the patient had a good clinical evolution, without further complications or the need for surgical intervention. This article discusses the complications presented, as well as a review of the literature on totally endoscopic surgery of the cervical spine.

1313

P426: Digital Guide to the Full Endoscopic Interlaminar Technique for the Treatment of Lumbar Canal Stenosis

Andre Calderaro ¹

¹ Centro Ortopedico Valqueire, Full endoscopia, Rio de Janeiro, Brazil

Introduction: Degenerative lumbar stenosis can be caused by bony, disc, capsular or ligament structures. Compression can lead to classic symptoms, such as neurogenic lameness with root signs. Back pain is more likely to be attributed to secondary degenerative phenomena, such as instability or segment deformities. Therapeutically, there is no robust evidence in the medical literature that makes it possible to recommend clinical treatment. the appearance and development of minimally invasive techniques has become a trend every day, among spine surgeons, for reducing tissue trauma and consequently the complications generated by conventional techniques and accesses. The concept of complete endoscopy and its practical application allow the patient, minimal tissue trauma, scar less than 1 cm, rapid post-surgical rehabilitation, without infection and with very good cosmetic results. For the surgeon, excellent intraoperative vision, an efficient and fast procedure and a high degree of acceptance by the patient. Material and Methods: We use original drawings, made by hand, associated with short videos, contemplating the step-by-step treatment of lumbar canal stenosis, by the full endoscopic technique with inter laminar access. This material was distributed to a group of 10 spine surgeons who systematically used the step by step suggested in their surgical procedures. Results: The procedures performed following the step by step, were classified by the surgeons, through a questionnaire, with and without complications, successful or not successful, relevant or not relevant help. Conclusion: The authors conclude that this digital tool, in a didactic, systematic and standardized way, help and assist the full endoscopic procedure by spine surgeons.

1371

P427: Risk Factors for Polyetheretherketone Cage Subsidence Following Minimal Invasive Transforaminal Lumbar Interbody Fusion

Weerasak Singhatanadgige ¹ , Worawat Limthongkul ¹ , Vit Kotheeranurak ² , and Wicharn Yingsakmongkol ¹

¹ Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand

² Queen Savang Vadhana Memorial Hospital, Bangkok, Thailand

Introduction: Minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) is currently popularized as a safe and effective treatment for patients with degenerative lumbar spine disease. A recognized complication of TLIF is cage subsidence within the disc space. This is associated with poor outcomes. Although various rates of cage subsidence after lumbar interbody fusion have been reported for various techniques and cage types, the number of studies that have addressed relevant risk factors for polyetheretherketone (PEEK) cage subsidence are limited. Using adult cohort of MIF-TLIF with cage in lumbar spinal disease patient, we aim to identify risk factor related to the incidence of cage subsidence after MISTLIF procedures. Material and Methods: This is a retrospective cohort study, 85 adult patients with MISTLIF with cage were included. Definitions to be present if a cage was observed to be sink into an adjacent vertebral body by > 2 mm on post-operative CT lumbosacral spine. Clinical variables (age, gender, BMI, BMD, diagnosis and fusion level) and Radiographic variables (Cage position, cage angle, cage proportion, screw angle, disc height ratio, lithesis reduction, bony union and multifidus mass) were evaluated. The odds ratio and its confidence interval were calculated. We performed a logistic regression analysis. Results: Sixty-five (76.4%) patients met the criteria for cage subsidence and 20 (23.6) patients were no cage subsidence. The mean age was 52 (range 30-80) years. The most significant variable associated with cage subsidence include older age of surgery (P = .032), cage position in posterior (P = .01) and lower cage proportion (P = .04). Conclusion: In MIS-TLIF with PEEK cage, older age of surgery, posterior position of cage and lower proportion of cage are predictive factor of cage subsidence.

1402

P428: Outcome Analysis of MIS-TLIF "Minimal Invasion Maximum Relief"

Yogendra Agrahari ¹ , Nandan Marathe ² , Jeevan Kumar Sharma ² , and Harvinder Singh Chhabra ²

¹ Shree Tinau International Hospital, Butwal, Nepal

² Indian Spinal Injury Center, New Delhi, India

Introduction: Degenerative spinal disease is one of the commonest problems in elderly population leading to back pain, radiculopathy, spinal instability and neurologic deficit. Surgical management is considered if there is further deterioration of neurologic symptoms and failed conservative management. With regards to surgery, with the emerging trends in technology MIS-TLIF has become popular in recent years. This technique helps to minimize iatrogenic soft tissue damage and decreases the risk of atrophy of the multifidus and/or longissimus muscle. This study aims to determine the pre-operative, intra-operative and post-operative findings in patients underwent with MIS-TLIF. Material and Methods: Retrospective evaluation of 43 patients was done from January 2014 to December 2018 from Spine department of tertiary level hospital. Every patients’ demographic data, preoperative and post-operative symptomatology data, clinical findings data on examinations were evaluated. Oswestry disability Index, Visual Analogue scale were used to assess the pain, disability, and health status preoperatively and postoperatively for the clinical outcomes. In addition, the operating time, estimated blood loss, and hospital stay were also recorded. The patients with chronic back pain with or without leg pain, neurological deficit due to degenerative spondylolisthesis, degenerative disc disease and recurrent lumber disc herniation treated with Transforaminal Lumber Interbody Fusion (TLIF) were included. Results/Conclusion: The male and female numbers were approximately similar and mean age group was 51.4.VAS and ODI scoring were decreased compared to preoperative evaluation. MIS-TLIF has better outcomes in terms of lesser blood loss, dural tear, infection, quicker improvement of back pain, and shorter hospital stay, instrument failure and also lower incidence of Adjacent Segment Disease (ASD) as compared to previously described data on TLIF in literature. A multicentric study with a larger sample size and an RCT comparing outcomes of MIS TLIF with conventional open TLIF will further validate our findings.

Keywords

degenerative spine disease, MIS-TLIF, ODI, VAS

1450

P429: Percutaneous Reduction of Thoracolumbar Fractures Using Monoaxial Screws: Comparison of Two Instruments Based on Initial Reduction and Loss of Reduction

Esra Aydin ¹ , Gunther O. Hofmann ^{1 2} , Philipp Schenk ^{1 2} , and Bernhard Ullrich ^{1 2}

¹ BG Klinikum Bergmannstrost Halle, Halle (Saale), Germany

² Universitätsklinikum Jena, Jena, Germany

Introduction: The minimally invasive surgery of thoracolumbar vertebral fractures is an essential part in spinal surgery. It offers many advantages compared to open surgical care. In this study, two percutaneous systems (Aesculap and DePuy) will be compared regarding reduction and the loss of reduction. Material /Method: In a monocentric study, data from patients with a fracture of the thoracolumbar transition (Th11-L2) were analyzed retrospectively. Using CT and X-ray images, bisegmental Cobb angles (CA) were measured at: T1: pre-, T2: intra- and T3: few days post-operatively. In addition the cut-suture time, the fracture morphology based on AOSpine, the bone quality using Hounsfield Units (HU) and complications were researched. The effect of both systems was investigated using ANOVA with repeat measurement (rmANOVA). Effects of HU on loss of reduction was examined using correlation. Results: In total data of 118 patients were evaluated in the study (Aesculap: N = 32, DePuy: N = 86, 75 male, 43 female, age: 49 ± 15 years, bone quality: 153 ± 45 HU). The most frequent fracture was found in L1 (N = 59), followed by Th12 (N = 35), L2 (N = 21) and Th11 (N = 3). There were no differences between Aesculap and DePuy concerning sex (P = .288), age (P = .232), bone quality (P = .937), level of fracture (P = .358) and cut-suture time of 58 ± 18 minutes (P = .977). The fracture morphology based on AOSpine was distributed unequally between both systems (P < .001), thus the AOSpine classification was considered as covariant in the following analyses. The analysis of the CA showed an effect of reduction (-11 ± 7°, P < .001), but also a loss of reduction from intra- to post-surgery (2 ± 4°, P < .001, figure 1). Still, there was a remaining effect of reduction (-9 ± 6°, P < .001). The used system showed no significant effect (P = .827). The AOSpine classification indicated no effect either (P = .136). Patients with bad bone quality tended to have more extensive reduction (P = -,257, P = .005), whereas there was no effect on loss of reduction (P = .226). Overall, only DePuy-patients (5 out of 86) showed complications (two implant failure, two innie loosening, one infection). Discussion: The study showed that there is no difference between Aesculap and DePuy concerning reduction. Despite the technical differences, a treatment of the injury can be achieved either way. HU has an effect on reduction and should be considered in the therapeutic decision. No correlation between HU and loss of reduction might be caused by the short follow up. Innie loosening was only seen in DePuy. This might be sample-caused or could be related to the technique of rod pushing.

1519

P430: Minimally Invasive Versus Open Surgery in Adolescent Idiopathic Scoliosis: A Systematic Review

Karim Aljian ¹ , Roozbeh Shafafy ² , and Sherief Elsayed ^{3, 4}

¹ Brighton And Sussex Medical School, Brighton, United Kingdom

² Royal National Orthopaedic Hospital, Stanmore, United Kingdom

³ Brighton & Sussex University Hospitals, Brighton, United Kingdom

⁴ NMC Spine, Dubai, United Arab Emirates

Introduction: Instrumentation through minimally invasive techniques is an appealing alternative to open surgery in adolescent idiopathic scoliosis (AIS). The advantages argued by its advocates over conventional instrumentation include superior cosmesis and reduced morbidity. However, there is paucity in the literature ascertaining the optimal choice of surgery. This study aimed to review the current evidence of minimally invasive surgical techniques in AIS and to compare outcome data with those of traditional open instrumentation through critical appraisal and analysis. Materials and Methods: A literature search was conducted on 4 databases (Cochrane library, EMBASE, Medline and Web of Science) using relevant search terms for studies comparing minimally invasive surgery to open surgery in AIS. The methods of open surgery included posterior spinal fusion (PSF) and open anterior spinal fusion (OASF). The minimally invasive techniques included in this study were thoracoscopic anterior spinal fusion (TASF) and minimally invasive posterior spinal fusion (MI-PSF). Randomised-controlled trials as well as retrospective and prospective cohort studies were included. A narrative synthesis was performed, evaluating radiographical, perioperative and patient reported outcomes in the form of SRS-22 questionnaires. Risk of bias for each study was assessed using the Classes of Evidence tool. Results: Nine studies met the inclusion criteria. Coronal Cobb angle correction rates were similar between minimally invasive techniques and open surgery. Minimally invasive surgery groups had significantly less intra-operative blood loss and length of hospital stay than open surgery groups, but significantly longer operation duration. In concurrence with these findings, a learning curve was widely reported among the studies in the minimally invasive groups. SRS-22 outcomes were significantly in favour of minimally invasive techniques in the pain and self-image categories in the two studies that directly reported them. Conclusion: The current evidence suggests that minimally invasive techniques in AIS offer similar rates of deformity correction to open procedures. Patient preferences that may indicate minimally invasive techniques over open surgery include smaller surgical scars, shorter hospital stay and less post-operative pain. However, the current quality and volume of evidence impedes any firm conclusions from being drawn. This systematic review accentuates the necessity for future high-quality long-term comparative studies to further establish the potential benefits and potential ramifications of these procedures.

1533

P431: Comparing Long-Term Outcomes Between Open and Minimally Invasive Transforaminal Lumbar Interbody Fusion in The Treatment of Lumbar Degenerative Disc Disease and Spinal Instability

Daniel Coban ¹ , Stuart Changoor ¹ , Conor Dunn ¹ , Michael Pompliano ¹ , Kumar Sinha ¹ , Ki Hwang ¹ , Michael Faloon ¹ , and Arash Emami ¹

¹ St. Joseph's University Medical Center, Paterson, NJ, USA

Introduction: Transforaminal lumbar interbody fusion (TLIF) has evolved as a treatment option for addressing various lumbar spinal disorders and is now an established, widely performed technique owing to high fusion rates. With the advent of new minimally invasive techniques, minimally invasive TLIF (MI-TLIF) offers potential advantages of reduced tissue trauma, blood loss, medication use and cost. These benefits are often easily marketable to patients; however, a paucity of literature exists directly comparing the efficacy of MI-TLIF to the traditional open technique in the long-term. Therefore, to justify the utilization of MI-TLIF over open TLIF, we must determine both the overall revision rates and functional clinical outcomes with long-term follow-up. Material and Methods: A retrospective review was performed to identify all patients between 2013-2018 who underwent either open or minimally invasive TLIF with a minimum follow-up of 2 years. Demographic data was recorded and compared between both cohorts. Revision rates and time to revision in each group was compared. Functional outcomes were assessed with ODI and VAS-l and VAS-b measurements at follow-up visits. All complications were reviewed. Standard binominal and categorical comparative analysis were performed. Results: A total of 320 consecutive patients were included, 95 in the open TLIF cohort and 225 in the MI-TLIF cohort. Mean follow-up for the open TLIF and MI-TLIF groups were 41.1 and 39.2 months, respectively. Complication rates were .9% and 4.2% for the MI and open cohorts, respectively (P = .04). The overall revision rates were 8.0% for the MI cohort and 7.4% for the open cohort (P = .85). Average time to revision was 376.3 ± 284.3 days and 295.0 ± 426.7 days for the MI and open groups, respectively (P = .05). The most common reason for revision in the MI-TLIF group was pseudarthrosis whereas the most common reason for revision in the open TLIF group was persistent radicular symptoms. Average blood loss was 79.2 ± 24.4 ml and 235.1 ± 40.3 ml in the MI and open groups, respectively (P = < .001). Average surgery time was 258.4 ± 35.1 minutes for the MI group and 248 ± 25.5 minutes for the open cohort (P = .01). There were 134 males and 91 females in the MI-TLIF cohort compared to 55 males and 40 females in the open TLIF cohort (P = .08). Both cohorts experienced significant improvements in their functional outcomes scores (ODI, VAS-leg, and VAS-back) compared to their pre-operative values, however the magnitude of improvement was not statistically significant between the MI-TLIF and open TLIF groups. Conclusion: MI-TLIF is a safe and effective alternative to open TLIF in the treatment of lumbar degenerative disc disease and spinal instability, demonstrating long-lasting benefit. After long-term follow-up, MI-TLIF demonstrated similar improvements in functional outcome scores, without increased complication or revision rates, and with the advantages of decreased hospital length of stay, overall cost, and quicker return to work. Further studies should consist of 5-year follow-up with cost analysis to evaluate how utilizing MI-TLIF would impact overall health-care spending.

1534

P432: PEEK Versus Titanium Cages in Transforaminal Lumbar Interbody Fusion: A 2-Year Follow up Study With Clinical and Radiological Outcomes

Daniel Coban ¹ , Stuart Changoor ¹ , Conor Dunn ¹ , Michael Pompliano ¹ , Kumar Sinha ¹ , Ki Hwang ¹ , Michael Faloon ¹ , and Arash Emami ¹

¹ St. Joseph's University Medical Center, Orthopedics, Paterson, NJ, USA

Introduction: Transforaminal lumbar interbody fusion (TLIF) has evolved as a treatment option for addressing various lumbar degenerative disorders. However, successful fusion is limited by the properties inherent to the interbody devices utilized. Despite widespread application, concern over the use of polyetheretherketone (PEEK) cages have been raised due to their intrinsic hydrophobicity and a lack of osteoconductivity. In contrast, superior rates of fusion and clinical outcomes have been reported in patient cohorts treated with titanium (Ti) cages, considering metal’s bioactivity in the role of spinal fusion. Current studies examining the utility of metal versus PEEK cages exist but describe small sample sizes with relatively short follow-up; thus, further investigation is warranted. To justify the utilization of Ti over PEEK cages in TLIF and to confirm prior hypotheses, we must compare the revision rate, graft subsidence rate, prevalence of fusion and functional outcomes of patients treated with both cage types. Material and Methods: A retrospective review was performed to identify all patients between 2013-2018 who underwent open or minimally invasive (MI) TLIF and received either a titanium or PEEK cage with a minimum follow-up of 2 years. Demographic data was recorded and compared between both cohorts. Revision rates, time to revision, graft subsidence and fusion rates in each group were also compared. Functional outcomes were assessed with ODI, VAS-l and VAS-b measurements at follow-up visits. Results: A total of 320 consecutive patients were included, 137 (42 open, 95 MI) in the Ti cohort and 183 (53 open, 130 MI) in the PEEK cohort. Mean follow-up of the PEEK and Ti cohorts were 44.2 and 40.8 months, respectively. Intraoperative complication rates were 2.7% and 3.7% for the PEEK and Ti cohort, respectively (P = .04). The most common complication was durotomy. The overall revision rates were 10.4% for the PEEK cohort and 2.9% for the Ti cohort (P = .01). Mean time to revision was 375.4 and 346.6 days for the Ti and PEEK groups, respectively (P = .48). The graft subsidence rate for the PEEK cohort at 3, 6, 12 and 24 months post-operatively was 2.7%, 5.5%, 7.7% and 9.8%, respectively. Subsidence in the Ti group was more favorable overall, showing 2.9%, 5.1%, 6.6% and 8.0% subsidence at the same time points. Successful spinal fusion at 24 months was 94.9% and 92.9% in the Ti and PEEK groups, respectively (P = .5). Both groups experienced significant improvements in their functional outcome scores (ODI, VAS-leg, VAS- back) compared to their pre-operative values. There were no statistically significant differences in complication rate, revision rate, graft subsidence, or spinal fusion rates between minimally invasive and open techniques within groups. Conclusion: The Ti cohort in this study demonstrated a higher rate of fusion, lower rates of revision and subsidence, and similar improvements in functional outcome scores as the PEEK cohort at the 2-year timepoint. Further studies should consist of randomized controlled trials with blinded assessments to definitively conclude the advantages of Ti cages for TLIF.

1539

P433: Open Versus Minimally Invasive Transforaminal Lumbar Interbody Fusion in the Treatment of Two-Level Degenerative Disc Disease

Daniel Coban ¹ , Stuart Changoor ¹ , Conor Dunn ¹ , Michael Pompliano ¹ , Kumar Sinha ¹ , Ki Hwang ¹ , Michael Faloon ¹ , and Arash Emami ¹

¹ St. Joseph's University Medical Center, Paterson, NJ, USA

Introduction: Transforaminal lumbar interbody fusion (TLIF) was first described by Harms and Rolinger in 1982 and has evolved as a treatment option for addressing various lumbar spinal disorders such as degenerative disc disease (DDD). More recently, minimally invasive TLIF (MI-TLIF) has been integrated into common surgical practice in an attempt to reduce muscle injury associated with the standard procedure, and has been reported to offer the advantages of decreased tissue trauma, blood loss, medication use and cost. These benefits are often easily marketable to patients; however, a paucity of literature exists directly comparing the efficacy of two-level MI-TLIF to the traditional open technique in the long-term. Therefore, to justify the utilization of MI-TLIF over open TLIF in the treatment of two-level degenerative disc disease, we must determine both the overall revision rates and functional clinical outcomes with long-term follow-up. Material and Methods: A retrospective review was performed to identify all patients between 2013-2018 who underwent either open or minimally invasive TLIF for two-level DDD with a minimum follow-up of 2 years. Demographic data was recorded and compared between both cohorts. Revision rates and time to revision in each group was compared. Functional outcomes were assessed with ODI and VAS-l and VAS-b measurements at follow-up visits. All complications were reviewed. Standard binomial and categorical comparative analysis were performed. Results: A total of 85 consecutive patients who underwent two-level surgery were included, 43 in the open TLIF cohort and 42 in the MI-TLIF cohort. Mean follow-up for the open TLIF and MI-TLIF groups were 40.8 and 43.4 months, respectively. Complication rates were 2.4% and 2.3% in the MI and open cohorts, respectively (P = .987), and were both a consequence of incidental durotomy which were subsequently repaired intraoperatively. The overall revision rates were 11.9% for the MI cohort and 7.0% for the open group (P = .437). Average time to revision was 517.6 ± 372.1 days and 629.0 ± 144.8 days for the MI and open groups, respectively (P = .071). The most common reason for revision in the MI-TLIF group was pseudarthrosis (60%), whereas the most common reason for revision in the open TLIF group was persistent radicular symptoms (66.7%). Average blood loss was 83.1 ± 26.2 ml and 222.9 ± 48.3 ml in the MI and open groups, respectively (P = < .001). Average surgery time was 256.1 ± 33.2 minutes for the MI group and 235 ± 20.2 minutes for the open cohort (P = < .001). Both cohorts experienced significant improvements in their functional outcome scores (ODI, VAS-leg, and VAS-back) compared to their pre-operative values; however, the magnitude of improvement was not statistically significant between the MI-TLIF and open TLIF groups. Conclusion: MI-TLIF is a safe and effective alternative to open TLIF in the treatment of two-level lumbar degenerative disc disease, demonstrating long-lasting benefit. After long-term follow-up, MI-TLIF demonstrated similar improvements in functional outcome scores, without increased complication or revision rates, and with the advantages of decreased hospital length of stay, overall cost, and quicker return to work.

1540

P434: Comparing Long-Term Outcomes Between Minimally Invasive Transforaminal Lumbar Interbody Fusion And Extreme Lateral Interbody Fusion in the Treatment of Lumbar Spinal Disorders

Daniel Coban ¹ , Stuart Changoor ¹ , Conor Dunn ¹ , Michael Pompliano ¹ , Kumar Sinha ¹ , Ki Hwang ¹ , Michael Faloon ¹ , and Arash Emami ¹

¹ St. Joseph's University Medical Center, Paterson, NJ, USA

Introduction: Minimally invasive lumbar fusion has developed into a popular surgical option for patients with degenerative lumbar pathology. These techniques offer similar clinical outcomes to the open approach, often reporting less complications in the long-term. However, there is a natural paucity in the literature directly comparing different minimally invasive approaches, as these are often compared singularly with their open counterparts. Minimally invasive transformational lumbar interbody fusion (MI-TLIF) and extreme lateral interbody fusion (XLIF) have both been progressively utilized by spinal surgeons, offering advantages of reduced tissue trauma, blood loss, medication use and cost. This leaves surgeons with more than one option for patients whom multiple minimally invasive approaches may be applicable. Therefore, the purpose of this study was to assess and compare the overall revision rates and functional clinical outcomes with long-term follow-up in both MI-TLIF and XLIF. Material and Methods: A retrospective review was performed to identify all patients between 2013-2018 who underwent XLIF of minimally invasive TLIF with a minimum follow-up of 2 years. Demographic data was recorded and compared between both cohorts. Revision rates and time to revision in each group was compared. Functional outcomes were assessed with ODI and VAS measurements at follow-up visits. Standard binominal and categorical comparative analysis were performed. Results: A total of 340 consecutive patients were included, 115 in the XLIF cohort and 225 in the MI-TLIF cohort. Mean follow-up for the XLIF and MI-TLIF groups were 46.3 and 39.2 months, respectively. The overall revision rates were 7.8% for the XLIF group and 8.0% for the MI-TLIF group, respectively (P = .929). Average time to revision was 376.3 ± 284.3 days and 404.1 ± 240.7 days for the MI-TLIF and XLIF groups, respectively (P = .366). The most common reason for revision in each cohort was pseudarthrosis in the MI-TLIF group (60.0%) and adjacent segmental disease in the XLIF group (44.4%). There were 134 males and 91 females in the MI-TLIF cohort compared to 46 males and 69 females in the XLIF cohort (P= < .001). Both cohorts experienced significant improvements in their functional outcome scores compared to their pre-operative values; however, VAS scores decreased by a mean of 5.6 in the XLIF group and a mean of 2.9 in the MI-TLIF group, a significant difference (P = < .001). Conclusion: Our two-year results suggest XLIF and MI-TLIF are reasonable minimally invasive alternatives for the treatment of lumbar spinal disease. After long-term follow-up, XLIF demonstrated superior improvement in VAS score, without increased revision rates. Both procedures offer advantages of decreased hospital length of stay, blood loss, and quicker return to work. Larger, prospective comparative studies are required to corroborate these findings.

1541

P435: A Comparison of Long-Term Outcomes Between Minimally Invasive Transforaminal Lumbar Interbody Fusion and Extreme Lateral Interbody Fusion in Obesity

Daniel Coban ¹ , Stuart Changoor ¹ , Conor Dunn ¹ , Michael Pompliano ¹ , Kumar Sinha ¹ , Ki Hwang ¹ , Michael Faloon ¹ , and Arash Emami ¹

¹ St. Joseph's University Medical Center, Paterson, NJ, USA

Introduction: Obesity, defined as a body mass index (BMI) >30 kg/m², is a global health problem that poses unique challenges to spinal surgeons in lumbar fusion procedures. Although obesity is associated with an array of comorbidities, this patient population still exhibits good outcomes when undergoing open surgery for degenerative diseases of the lumbar spine. Minimally invasive transformational lumbar interbody fusion (MI-TLIF) and extreme lateral interbody fusion (XLIF) have both been progressively utilized by spinal surgeons, offering advantages of reduced tissue trauma, blood loss, medication use and cost. With an increasing prevalence of obesity in the population, it is imperative to understand the long-term outcomes in minimally invasive techniques. Therefore, the purpose of this study was to assess and compare the overall revision rates and functional clinical outcomes in the obese with long-term follow-up in both MI-TLIF and XLIF. Material and Methods: A retrospective review of our institution’s database was performed in order to identify all obese patients between 2013-2018 who underwent XLIF or minimally invasive TLIF with a minimum follow-up of 2 years. Demographics including BMI were recorded. Patients were categorized as obese and included in the study if their BMI at the time of surgery was >30 kg/m². Reoperation rates were compared between cohorts. Functional outcomes were assessed by comparing pre- and post-operative VAS and ODI scores. Results: A total of 144 consecutive patients were included, 62 in the XLIF cohort and 82 in the MI-TLIF cohort. The overall revision rates were 8.5% and 9.6% for the MI-TLIF and XLIF groups, respectively (P = .813). The most common reason for revision in obese patients who underwent XLIF was adjacent segment disease (50%), whereas pseudarthrosis (50%) was the most commonly cited reason for revision in obese patients who underwent MI-TLIF. There were 45 males and 37 females in the MI-TLIF cohort compared to 31 males and 31 females in the XLIF cohort (P = .562). Both cohorts experienced significant improvements in their functional outcome scores compared to their pre-operative values. VAS scores decreased by a mean of 5.4 in the XLIF obese group and a mean of 3.9 in the MI-TLIF obese group (P = < .001). ODI scores decreased by a mean of 23.3 in the XLIF obese group and a mean of 15.9 in the MI-TLIF obese group (P = < .001). Conclusion: Our two-year results suggest XLIF and MI-TLIF are reasonable minimally invasive alternatives for the treatment of lumbar spinal disease in the obese population. After long-term follow-up, XLIF demonstrated superiority in functional clinical outcomes scores, without significantly increased revision rates. Both procedures offer advantages of decreased hospital length of stay, blood loss, and quicker return to work compared to their open counterparts. Larger, multi-institutional, prospective studies are required to confirm these findings.

1542

P436: Comparing Long-Term Outcomes Between Minimally Invasive Transforaminal Lumbar Interbody Fusion And Extreme Lateral Interbody Fusion in the Treatment of Low-Grade Degenerative Spondylolisthesis

Daniel Coban ¹ , Stuart Changoor ¹ , Conor Dunn ¹ , Michael Pompliano ¹ , Kumar Sinha ¹ , Ki Hwang ¹ , Michael Faloon ¹ , and Arash Emami ¹

¹ St. Joseph's University Medical Center, Paterson, NJ, USA

Introduction: Low-grade lumbosacral degenerative spondylolisthesis (DS) is a common cause of chronic back pain that is often treated with surgical intervention when conservative measures fail. With recent advancements in surgical techniques, minimally invasive transforaminal lumbar interbody fusion (MI-TLIF) and extreme lateral interbody fusion (XLIF) have both been progressively utilized by spinal surgeons in the treatment of DS, offering advantages of reduced tissue trauma, blood loss, medication use and cost. However, challenges in surgical decision making surrounding the use of minimally invasive surgery have emerged due to a natural paucity of studies comparing the effectiveness of these novel approaches. Therefore, the purpose of this study was to assess and compare the overall revision rates and functional clinical outcomes of MI-TLIF versus XLIF in the treatment of low-grade DS. Material and Methods: A retrospective review was performed to identify all patients between 2009-2014 who underwent XLIF or minimally invasive TLIF with a minimum follow-up of 5 years for low-grade degenerative spondylolisthesis. Demographic data was recorded and compared between both groups. Reoperation rates were compared between cohorts. Functional clinical outcomes were assessed by comparing pre- and post-operative VAS and ODI scores. Results: A total of 65 patients were included, 34 in the XLIF cohort and 31 in the MI-TLIF cohort. Mean follow-up for the MI-TLIF and XLIF groups were 70.1 and 73.2 months, respectively. The overall revision rates were 12.9% and 5.9% for the MI-TLIF and XLIF groups, respectively (P = .329). Of the two patients who required reoperation in the XLIF group, one was indicated by adjacent segment disease and the other was indicated by subsequent development of pseudarthrosis. Four patients were revised in the MI-TLIF group. Two patients required reoperation for persistent radicular symptoms, one patient developed pseudarthrosis and one patient developed diskitis postoperatively. There were 14 females and 17 males in the MI-TLIF cohort compared to 21 females and 13 males in the XLIF cohort (P = .180). Both cohorts experienced significant improvements in their functional outcome scores compared to their pre-operative values; however, the magnitude of improvement was not statistically significant between the MI-TLIF and XLIF groups. Conclusion: Five-year follow-up results suggest that XLIF and MI-TLIF are both reasonable minimally invasive alternatives for the treatment of low-grade degenerative spondylolisthesis. After long-term follow-up, there were less revisions in the XLIF cohort, however the difference was not statistically significant. Both procedures demonstrated similar improvements in functional outcome scores and offer advantages of decreased hospital length of stay, blood loss, and quicker return to work. Larger, prospective comparative studies are required to corroborate these findings.

1556

P437: Anterior Lumbar Spinal Fusion Perioperative Morbidity and Mortality Utilizing the National Inpatient Sample (NIS): 2005-2013

Conor Dunn ¹ , Stuart Changoor ¹ , Kumar Sinha ¹ , Ki Hwang ¹ , Michael Faloon ¹ , and Arash Emami ¹

¹ St. Joseph's University Medical Center, Paterson, NJ, USA

Introduction: Lumbar spine fusion has become an increasingly popular surgical treatment to address common pathologies of the spine. The past two decades have seen significant changes in the instrumentation and surgical approaches that has improved fusion rates and surgical outcomes. The advancement of lumbar fusion surgery, combined with an increasingly aging population, has led to an increase in the number of procedures performed. The anterior approach to the lumbar spine has its own specific technical challenges and associated risks. The National Inpatient Sample (NIS) serves as the single largest all-payer inpatient database in the USA and provides weights for nationally representative estimates. For this reason, it serves as an appropriate approximation of the overall perioperative morbidity and mortality statistics for this and other procedures. The purpose of this study is to evaluate the perioperative morbidity and mortality, as well as demographics of patients undergoing lumbar spinal fusion via an anterior approach from the most recent data from 2005 to 2013. Material and Methods: The NIS database was reviewed from 2005 to 2013. Patients undergoing elective lumbar fusion surgery via an anterior approach were identified by ICD-9 code. Indications specific to the lumbar spine, such as lumbar degenerative disc disease, herniated disc, stenosis, or radiculopathy were also identified by their respective ICD-9 codes. Demographics including age, sex, hospital region and teaching status, insurance status, race/ethnicity, median household income and CCI score were assessed. Frequencies of complications including PE, DVT, infection, cardiac, hematoma, durotomy, and mortality were also analyzed. Statistical analysis involved T tests, χ2 analysis, and binary logistic regression with P < .001 denoting significance. Results: We identified 27,912 patients which represented an estimated 137,928 of weighted patients hospitalized for primary anterior lumbar spine fusion. patients undergoing anterior lumbar fusion had a mean age of 55.4 (+/- 14.3) with 55.3% female patients. The majority of patients were white (82.2%), privately insured (50.4%), had a median household income of $48,000-62,999 (27.1%) and with a CCI score of 0.44 (+/-.8). The majority of procedures were performed in the South region (39.5%), in nonteaching hospitals (54.5%), in private, not for profit hospitals (70.4%). Bone Morphogenic Protein was used in 43.4% of cases. The most common complication was durotomy (1.2%) followed by cardiac complications and hematoma (.7%) with the least common being PE (.1%). The mortality was .2% for this procedure. Conclusion: Anterior lumbar fusion is a commonly used surgical approach nationally, in teaching and nonteaching hospitals, with low rates of complications and overall mortality. We expect, with the advancements in instrumentation, success rate of fusions, and an aging population, that anterior fusion will continue to see an increase in utilization by spine surgeons across the country.

1688

P438: Anterior Plate Fixation Compared to Transpedicular Screw Fixation in OLIF Surgery

Márton Rónai ¹ , Kristóf József ¹ , and Aron Lazary ¹

¹ National Center For Spinal Disorders, Budapest, Hungary

Introduction/Background: In the last two decades, Oblique Lumbar Interbody Fusion (OLIF) became more and more popular to perform lumbar fusion in a less invasive way. One of the advantages of doing such an approach is to make as minimal injury to the paraspinal musculature as possible. Nonetheless, OLIF surgeries are usually performed by doing an anterior approach to place the interbody spacer, and then an MIS transpedicular screw fixation is done which inevitably damages the paravertebral muscles at a certain level. Transpedicular screw fixation is known to be the most stable construct to fix a lumbar segment, however anterior plate fixation is also wildly used for unstable situations such as lumbar fractures. Based on this experience we started to use anterior plate fixation in OLIF procedures to reduce the invasiveness of the surgery. In this study, we present our results of a retrospective analysis of a cohort of consecutive patients who underwent single level OLIF surgery either with transpedicular screw fixation or anterior plate fixation. Material and Methods: Since 2017 68 patients were operated by one level OLIF surgery in our Institute. 61 of them had transpedicular screw fixation (TPSF) and 7 had anterior plate fixation (APF). The demographic data and the indication for surgery did not differ in the two groups, the decision to perform either one or the other type of fixation was done by the operating surgeon, who was always a senior consultant in both groups. To evaluate the strain of the surgery on the patients, we compared the operating time, the blood loss, and the amount of Morphine needed in the perioperative 24 hours. We also compared the length of hospital stay (LOHS), and for those patients who had at least 12 months of follow-up (30 and 6), the patient-reported outcome results (PROR). We used the Shapiro-Wilk, Mann-Whitney, and Khi-square tests for statistical analysis. Results: In the group of patients stabilized by APF the mean operating time was significantly shorter (130.7 vs 175.2 minutes; P < .001), and the mean need for Morphine in the perioperative 24 hours was significantly less (40.29 vs 69.76 mgs; P < .001). We found a trend to shorter mean LOHS in the group of patients with APF (4.00 vs 5.09 days; P = .093). There was no difference between the groups in the mean loss of blood (95.7 ml vs 94.6 ml; P = .922) and PROR at 12 months follow up (P = .373). Conclusions: These results suggest that OLIF surgery combined with anterior plate fixation may provide at least as good clinical results as with transpedicular screw fixation while further minimize the invasiveness of the procedure.

1716

P439: Preliminary Study of Fluid's Pressoric Conditions in Full Endoscopic Spine Surgery

Marcos Vaz De Lima ¹ , Antonio Roth Vargas ² , Enrico Ioriatti ³ , and Marco Moscatelli ⁴

¹ Santa Casa de São Paulo, Orthopedics, São Paulo, Brazil

² Centro Médico de Campinas, Campinas, Brazil

³ Endospine Center, São Paulo, Brazil

⁴ Neurolife, Natal, Brazil

The full endoscopic procedure is performed through a single channel with fluid current irrigation (saline) with variable flow, however with constant pressure as will be demonstrated in this study. It is called "submerged surgery". Particularly in that type of surgical technique, in the work channel, in its particular “surgical environment”, there are four different pressures to be considered: 1- the pressure of arterial vessels, 2 - the pressure of venous vessels, 3- the pressure of the irrigation fluid (serum physiological) that is irrigated in the spinal canal, but in the extra dural, and 4 - the pressure of the intra dural liquor. Although it is possible in irrigation equipment (“pump”) vary the pressure irrigation, the study shows that it will remain practically constant with minor variations attributed vertical movement of the optic caused by the surgeon in the to obtain the “zoom” effect of the images during the surgery. Fluid pressure was measured during the procedure in 12 sequential patients randomly selected for sex, weight and age, during total endoscopic surgery (surgery submerged) of the lumbar spine. The patients had herniated disc L5 / S1 or L4 / 5 randomly as to the type of hernia or laterality diagnosed through symptoms classics of lumbar disc herniation and MRI images. The procedures were performed under general anesthesia by interlaminar aproach in prone position. The average pressure of the fluid observed in the work environment was 24.5 mmHg (15-34 mmHg), that is, always below blood pressure, even when the pressurizer was used, at the same time always above venous pressure and above CSF pressure. The goal of this study is to establish the relationship between all pressures involved in the procedure and provide evidence of dural injury in fully endoscopic spine surgery can be severe for the patient, since due to the gradient pressure fluid established, the fluid is introduced into the subarachnoid space rather than spillage from it. The net flow occurs in reverse. For this reason, the authors recommend the use of only saline in this surgical technique without adding any type of substance such as adrenergics or anesthetics mixed with fluid.

1780

P440: Clinical Outcomes and Safety of a Low Profile 4.75 mm Pedicle Screw Fixation Following Minimally Invasive Lumbar Fixation

Nirmal Patil ¹ , Carlos De La Torre ¹ , and Khai Lam ¹

¹ London Bridge Hospital, Spine surgery, London, United Kingdom

Introduction: Violation of the cranial facet joint during pedicle screw fixation is one of the main causes of adjacent segment disease. The pedicle screw track traversing the facet joint and tulip of the pedicle screw impinging on the facet are some of the causes for facet joint dysfunction. We hypothesize that a low profile 4.75mm pedicle screw fixation has a low incidence of facet joint violation. The authors present the early clinical outcome and safety obtained in patients who underwent minimally invasive low profile pedicle screw fixation following anterior lumbar spine fusion surgeries, namely ALIF, LLIF and OLIF. Methods: Between September 2017 and October 2019, 44 patients underwent low profile pedicle screw fixation following various anterior lumbar spine surgeries. Pedicle screws were implanted using computer navigation. Patients' charts were retrospectively reviewed for operative time for the screw insertion, estimated blood loss (EBL), hospital length of stay (LOS). Other secondary patient related outcome measures (PROMS) were collected namely Oswestry Disability Score (ODI), Short-Form (SF)-36, EQ-5D healthy status, EQ-5D index, and Visual Analogue Pain (VAS) back and leg at 6 weeks, 12 weeks, 6 months and 12 months. Results: The mean age was 49 years (35 - 74 years) with 22 males and 22 females. All patients were followed up to 12 months post-surgery. The mean EBL loss was 100 ml and LOS 4.1 days. There were 25 ALIFs, 16 LLIFs and 3 OLIFs. A combination of CT scans intra and postoperative showed optimal implant positioning with no evidence of facet joint violation. The mean ODI improved from 44.3 (baseline), to 30.2 (6 weeks), 24 (3 months), 18.3 (6 months), and 15.9 (12 months); SF36 physical component improved from 44.7, to 51.3, 52.9, 56.1, and 56.2; SF36 mental component scores improved from 22.6, to 39.1, 42.1, 46.4, and 46.9; EQ-5D healthy status improved from 53.2, to 72.9, 77, 81.3, and 83; VAS back pain scores improved from 6.5, to 3.2, 2.6, 1.9, and 1.6; VAS leg pain scores improved from 5, to 2.4, 1.6, 1.3, and 1; EQ-5D index improved from .49, to .63, .69, .78, and .78. All PROMs measured showed statistically significant improvements at each time interval (P < .001). 63.1% of the patients were fully integrated back into their job at 12-month follow-up. There were no instances of major surgery-related complications, pseudarthrosis, or hardware failure at the final 12-month follow-up. Conclusions: The low profile 4.75mm pedicle screw is easy to implant, associated with minimal operative risk, and showed no risk of facet joint violation with good to excellent improvement in all PROM scores. The EBL and hospital LOS were shorter, and these features are entirely consistent with the goals of minimal invasive computer navigated spinal technologies.

1815

P441: Comparative Evaluation of the Effectiveness of Transpedicular Sequestrectomy and Microdiscectomy in the Treatment of Highly Migrated Disc Herniations

Igor Basankin ¹ , Abram Guilzatyan ¹ , Sergey Malakhov ¹ , and Karapet Takhmazyan ¹

¹ Reaearch Institute Krasnodar Regional Hospital 1, Krasnodar, Russian Federation

Introduction: Surgical treatment of highly migrated disc herniation (behind the pedicle of the vertebra) is a challenge and does not have a unique solution. In this paper, we compare the effectiveness of transpedicular endoscopy and standard microdiscectomy in the treatment of patients with this pathology. Materials and Methods: There were analyzed the results of surgical treatment of 28 patients, divided into 2 groups: group 1 - 13 patients after transpedicular endoscopic herniation removal, group 2 - 15 people after microdiscectomy. Results: Intraoperative parameters (length of incision, blood loss, duration of operation) were significantly better (P < .01) in patients who underwent transpedicular endoscopic disc herniation. In both groups, the intensity of leg pain according to VAS significantly decreased on average from 7.4 ± 1.3 to .7 ± .7 in group 1, and from 7.1 ± 1 to .8 ± .5 in group 2 in the first day after surgery. Back pain after surgical treatment in patients of group 1 regressed from the initial 5.2 ± .7 to 1.1 ± .89 by the end of first day, and after 1 year it was .6 ± .5. In group 2, this parameter decreased from the initial 4.9 ± 1 to 2.5 ± .9 on the first day, and after 1 year it averaged 2.8 ± 2.3 points. Excellent and good results on the Macnab scale after transpedicular endoscopic surgery were obtained in all 13 (100%) patients, among patients treated by microdiscectomy, similar results were obtained in 80%. Conclusion: Transpedicular endoscopic sequestrectomy is an optimal method for removing highly migrated disc herniations, which provides patients quick recovery and the absence of complications.

1818

P442: Biportal Endoscopic Discectomy Versus Uniportal Endoscopic Discectomy for Lumbar Disc Herniation: A Comparative Cohort Study in the Learning Curve Phase

Yu Keyi ¹

¹ Peking Union Medical College Hospital, Orthopaedic, Beijing, China

Objectives: We conducted this study to compare the surgical outcome and safety between biportal endoscopic discectomy (BED) and uniportal endoscopic discectomy (UED) in treatment of LDH in the learning curve phase. Methods: A retrospective analysis of 30 patients with LDH from April 2013 to September 2020 was performed, including 10 patients treated with BED (BED group) and 20 patients treated with uniportal endoscopic discectomy (UED group). All those cases were done by the same surgeon in the learning curve (0-10, 0-20 respectively). The demographic information, physical examination, radiological evaluations, and perioperative indicators were compared between two groups. The clinical outcomes were assessed according to the Oswestry Disability Index (ODI), Visual Analog Scale (VAS), and modified MacNab criteria. Results: The postoperative ODI scores and VAS scores were significantly improved in both groups compared with preoperative baseline (P < .001) and the satisfactory rates were 90.5% in two groups according to the modified MacNab criteria. There were no significant differences in the clinical outcomes and complication rate (P > .05), however, The UED group was superior in regards to the reduced blood loss and postoperative drainage, as well as the shorten operation duration (P < .001). The UED group had 1 dural injury, 1 nerve root injury, the BED group had 1 case converted to uniportal endoscopic surgery due to intra-operative bleeding with poor surgical field. Conclusions: BED has a similar outcome as the UED method for the treatment of LDH. BED need to resect more bony structure with more surgical time and more bleeding. But BED is safer for beginner to deal with L4-5 level or upper level with less neural injury in the learning curve.

Keywords

lumbar, umbar disc herniation, Percutaneous endoscopic discectomy, uniportal endoscopy, biportal endoscopy

1875

P443: Comparative Analysis of Transforaminal Full Endoscopic Lumbar Discectomy for the Treatment of Lumbar Disc Herniation and Radiculopathy vs Discogenic Low Back Pain. Single surgeon Experience With 193 Patients

Wael Chaaban ¹

¹ Healthpoint Hospital LLC, Spine Unit, Orthopedic department, Abu Dhabi, United Arab Emirates

Introduction: Several minimally invasive techniques are widely used to treat chronic Discogenic Low Back Pain (DLBP) with variable clinical outcomes. Full endoscopic lumbar discectomy followed by thermoradiofrequency is considered to be a minimally invasive technique to treat this condition, and has shown to be an effective and safe procedure for the treatment of Lumbar Disc Herniation and Radiculopathy. Materials and Methods: 193 Patients between August 2012 and July 2019 underwent to Single Level Full Endoscopic Lumbar Discectomy by a single surgeon with with a minimum follow up of 1 year were included in the study. These patients were divided in 2 groups, First group where included all patient with Preoperative diagnosis of Lumbar disc herniation and Radiculopathy and named LDH Group; the Second Group where included all patient with Preoperative diagnosis of Discogenic Low Back pain and named DLBP Group, the study include 155 male and 80 females. Patients with more than 1 level Disc pathology and other spinal co-morbidities were not included in the study. Transforaminal approach was chosen for all patients. Side of approach was decided based on dominant symptoms side. A 25° scope was used to operate all cases where discectomy followed by thermoradiofrequency was performed. The Visual Analogue Scale (VAS) and Oswestry Disability Index (ODI) were measured before the procedure and at 3, 6 and 12 months after the procedure. Overall patient satisfaction Recurrence/re-intervention rate, Incomplete decompression, overall complication and complication/related factors were also measured in the study. Results: 151 patients with mean age of 37.93 (18 - 68yr) were included in LDH Group and 42 patients with mean age of 37.5 (20 - 62yr) were included in DLBP Group. Overall satisfaction rate was significantly higher in LDH Group 96.69 (n:146) compared with DLBP Group 73.81% (n:31). The VAS and ODI had both significant improvement after the procedure which keep improved up to 1 year. The overall complication rate in LDH Group was 3.96% (n = 6); Infection 1.32% (n = 2), Incomplete decompression 1.32% (n = 2), Recurrence 1.32% (n = 2) but only 1 patient was symptomatic and required a new procedure. The overall complication rate in DLBP Group was 7.14% (n = 3) being all Postoperative infection of which one patient required surgical cleaning and fusion surgery. Transitory postoperative dysesthesia was seen in 11 patients of LDH Group whereas No patient of DLBP group had this undesirable post operative outcome. Prolonged operative time (>90min) was the most significant related factors linked to post operative dysesthesias. Conclusion: Full Endoscopic Lumbar Discectomy is an effective and safe surgical procedure for the treatment of selected group of patients with Lumbar Disc Herniation and Radiculopathy; whereas an exhaustive and detailed Preoperative evaluation and enhancement of diagnostic images and procedures must be implemented for the Accurate diagnosis of Discogenic Low Back Pain.

1898

P444: Lateral Lumbar Spine Decompression: A Systematic Review

Mustfa Manzur ¹ , Andre Samuel ² , Kyle Morse ² , Karim Shafi ² , Bridget Jivanelli ² , Sheeraz Qureshi ² , and Sravisht Iyer ²

¹ Sidney Kimmel Medical College at Thomas Jefferson University, Philadelphia, USA

² Hospital for Special Surgery, New York, USA

Introduction: Indirect decompression via a lateral lumbar interbody fusion can be utilized to treat central and foraminal lumbar stenosis. In cases of severe central stenosis, additional posterior direct decompression may be performed in conjunction with lateral interbody fusion. The aim of this systematic review is to synthesize the existing literature on these two techniques and identify any significant differences in outcomes or complications between isolated indirect decompression from lateral interbody fusion and indirect decompression with additional direct posterior decompression surgery. Material and Methods: A database search algorithm was utilized to query three databases (MEDLINE, COCHRANE, and EMBASE) and identify literature reporting decompression study groups that involved an oblique or lateral spinal fusion approach through May 2020. Improvements in outcomes measures and complication rates were pooled and tested for statistically significant differences between cohorts. Results: A total of 110 publications were assessed with 15 studies meeting inclusion criteria, including 557 patients and 1008 vertebral levels. Mean age was 63.1 years (SD = ±11.6) with BMI of 27.5 kg/m2 (SD = ± 4.1). Mean follow-up period was 17.6 months (SD = ± 9.6). For the direct decompression cohort, lumbar lordosis (LL) increased by 133.9%, from 22.8o to 48.7o, while the indirect decompression cohort LL increased by 8.9%, from 41.9o to 45.5o. The difference in LL improvement between cohorts was not statistically significant (P > .05). Oswestry Disability Index (ODI) decreased from 36.5 to 19.4 in the direct decompression cohort, and from 44.4 to 23.1 in the indirect decompression cohort. This difference in ODI reduction was also not statistically significant between cohorts (P = .053). Conclusion: Prior studies of indirect decompression and direct decompression of lumbar spine stenosis are limited by small sample sizes, heterogeneous populations, and a lack of direct comparisons. Both procedures result in improved function and pain postoperatively with direct decompression additionally restoring more lordosis in patients with worse preoperative alignment. Future prospective investigation is warranted, comparing these two techniques in a study with increased power and a similar patient population across groups. While both direct and indirect decompression are effective in specific patient populations, without this type of prospective comparison the ideal indications for an isolated indirect decompression cannot be determined.

1899

P445: Giant Disc Herniation Treated With Tubular Unilateral Approach for Bilateral Decompression

Fabian Sommer ¹ , Sertac Kirnaz ¹ , Lynn McGrath ¹ , Jacob Goldberg ¹ , Branden Medary ¹ , Franziska Anna Schmidt ² , and Roger Härtl ¹

¹ Weill Cornell Medicine, New York, USA

² Medizinische Universität Innsbruck, Innsbruck, Austria

Introduction: Disc herniations that obstruct the spinal canal by more than 50% are considered “Giant Disc Herniations” (GDHs). GDHs are less common than disc herniations of smaller volume, but they more frequently cause severe pain and neurological disorders. GDHs are challenging to treat from a surgical perspective due to their size. As a result of their surgical challenges, it is debated if minimally invasive tubular approaches are an effective and safe treatment for lumbar GDHs. In order to evaluate the efficacy and safety of the surgical treatment of lumbar GDHs using tubular minimally invasive surgery (MIS), we investigated the viability of the procedure. Materials and Methods: We conducted a retrospective study evaluating patients who had undergone tubular MIS at our clinic by our senior surgeon in the period from 01/2015 to 03/2020 due to a lumbar disc herniation. A total number of 227 cases were identified. Based on the MRI images, cases with spinal canal narrowing that was more than 50% were included in the study. After analysis, 22 (9.7%) cases met the criteria of a GDH. Age, gender and BMI were recorded and assessed. In addition to these parameters, the presence of neurological deficits such as cauda equina syndrome were evaluated. Furthermore, the surgical time, complications, estimated intraoperative blood loss and number of surgical revisions were recorded. All procedures were performed using tubular microsurgical techniques with the assistance of a microscope. The surgical procedure was performed through an 18 mm tubular retractor. Modification of technique compared to regular tubular discectomy was that we first performed an over-the-top bilateral decompression in order to create room for the safe performance of the discectomy. Results: 22 patients were included in the study. The patients had a mean age of 49.8 (+/-18) years. In the included cases, 59% (n = 13) of the patients were male and 41% (n = 9) were female. The mean BMI was 26.6 (+/- 5.4) m²/kg. The average surgery time was 109 (+/- 46) min with an average estimated blood loss of <10 ml (minimal). In all the patients, their GDH was treated successfully by tubular MIS. In two cases (9%), initial clinical symptoms reoccurred. In total, clinically significant weakness occurred in 5 patients (23%) prior to surgery, and 3 of the 5 patients had clinically manifested cauda equina syndrome (14%). The cauda equina syndrome resolved in all cases. The average hospital stay was 2 (+/- 0.7) calendar days. In no case was a change in procedure from MIS to open surgery necessary. Conclusion: Tubular MIS is suitable for the surgical treatment of GDHs. The rate of revision surgery was low in our cohort and the number of complications was also low. However, due to the size of the number of cases, our results should be considered within context. To quantify the exact benefit of MIS, further studies are necessary.

1905

P446: Bilateral Lumbar Erector Spinae Plane Blocks Reduce Postoperative Pain and Opioid Requirements in Minimally Invasive Transforaminal Lumbar Interbody Fusion (MI-TLIF)

Avani Vaishnav ¹ , Douglas S Wetmore ¹ , James D Beckman ¹ , Todd Albert ¹ , Catherine Himo Gang ¹ , and Sheeraz Qureshi ¹

¹ Hospital for Special Surgery, New York, USA

Introduction: Erector Spinae Plane (ESP) block is a relatively new fascial plane block that has been described for the management of chronic neuropathic pain and postoperative pain in abdominal and thoracic procedures, and hip surgery. However, the current literature on ESP blocks in spine surgery is limited. Thus, the purpose of this study was to evaluate the impact of ESP blocks on postoperative pain, opioid requirements and perioperative outcomes in MI-TLIF. Material and Methods: Patients undergoing MI-TLIF by a single surgeon and single anesthesiologist from Feb’19–Nov’19 who received bilateral Lumbar ESP blocks were selected (22 patients, Group E). Revision surgeries and patients with chronic opioid use were excluded. From a historic cohort of MI-TLIF patients (Apr’17-Nov’18), an age and gender matched control group that did not receive an ESP block was selected (Group NE). Postoperative pain, opioid consumption (oral morphine milligram equivalents – MME and need for intravenous patient controlled analgesia – IV-PCA), complications and length of stay (LoS) were compared. Chi square test and Fisher’s exact test were used to compare categorical variables, and student t-test and Mann Whitney u-test were used to compare normally and non-normally distributed continuous variables respectively. Statistical significance was set at p<0.05. Block Technique: All patients received a standardized anesthetic with multimodal analgesia. All ESP blocks were performed by the same anesthesiologist (30 ml of 0.375% bupivacaine with 2mg preservative free dexamethasone per side). In addition, all patients received local anesthetic infiltration (30ml of 0.5% bupivacaine with epinephrine) at the end of surgery. Results: Forty-four patients, 22 in group E and 22 in Group NE were included. There were no significant differences in demographics, operative factors or in-hospital complications. There were no intraoperative complications in either cohort. Group E had lower 24hr opioid consumption (median = 22.5 MME vs 57.5 in NE, P < .0001), primarily due to lower opioid consumption in the 0-6 hrs post-operative period (P = .034) and less need for IV-PCA (0 vs 22.7% in NE, P = .048). Intraoperative opioid requirements were lower in Group E (median=40 MME vs 75 in NE, P < .0001). Highest pain score within 3hrs of surgery was median of 7 and 8 in Group E and NE, respectively (P = .140). However, Group E reported significantly lower average pain (median NRS = 3.3 vs 5.1 in NE, P = .034). Group E also reported no opioid-related side effects versus rates of 4.5%, 4.5% and 9.1% for nausea/vomiting, ileus and urinary retention, respectively in Group NE; however, this difference was not statistically significant. There was no difference in LoS (Group E: median = 24hrs vs NE: 26; P = .250), with about 70% of patients in both groups being discharged on post-operative day 1 (P = .388). Conclusion: Our results show that ESP blocks resulted in a clinically significant reduction in opioid consumption in the perioperative period and average NRS pain score on POD 0, with no difference in complications or length of stay. Larger randomized studies are required to validate these findings and confirm the benefit of ESP blocks in spine surgery.

1909

P447: Comparison of Outcomes of Primary and Revision Minimally Invasive Lumbar Microdiscectomy

Avani Vaishnav ¹ , Hikari Urakawa ¹ , Kosuke Sato ² , Chirag Chaudhary ¹ , Jung Kee Mok ³ , Ryan Lee ⁴ , Catherine Himo Gang ¹ , and Sheeraz Qureshi ¹

¹ Hospital for Special Surgery, New York, USA

² University of Tsukuba, Tsukuba, Japan

³ Weill Cornell Medical College, New York, USA

⁴ George Washington University School of Medicine, Washington, DC, USA

Introduction: Although revision surgery carries a higher risk of complications due to dissection through scarred tissue planes, minimally invasive (MIS) techniques are increasingly being utilized to avoid scar tissue from previous approaches. However, it is not currently known whether there is a difference in outcomes between primary and revision MIS lumbar microdiscectomy. Thus, the purpose of this study was to compare outcomes of primary and revision MIS lumbar microdiscectomy. Material and Methods: A retrospective review of prospectively collected data of patients who underwent 1-2 level MIS lumbar microdiscectomy was performed. Patient demographics, operative data, clinical outcomes (length of stay, narcotic consumption, complications and reoperations) and patient-reported outcomes [PROMs– Oswestry Disability Index (ODI), VAS back& leg pain, SF-12 physical (PHS) and mental health (MHS) and PROMIS physical function] of primary and revision surgery were compared. Chi square test and Fisher’s exact test were used to compare categorical variables, and student t-test and Mann Whitney u-test were used to compare normally and non-normally distributed continuous variables respectively. Statistical significance was set at P < .05. Results: 195 patients (Primary = 166, Revision = 29) were included. The revision cohort was younger (42 vs 48yrs for primary, P = .033), had a lower Charlson Comorbidity Index (.06 vs .36, P = .006) and shorter operation time (42 vs 48mins, P = .033). There were no differences in smoking status (P = .830), insurance type (P = .689), ASA class (P = .925), post-operative narcotic consumption (P = .927) or length of stay (P = .968). 90% of patients in both cohorts were discharged on the day of surgery. The only operative complication was 1 Dural tear (0.6%) and the only in-hospital complication was urinary retention (n=3, 1.8%), all in the primary cohort. During the follow-up period, complications managed non-operatively were significantly greater in the revision cohort [n=3(10.3%) vs n = 4(2.4%) for primary, P = .035). However, there was no difference in reoperations [Primary: n = 12(17.2%); Revision: n = 3(10.3%); P = .472]. Reasons for reoperation were- Primary cohort: recurrent disc herniation (n = 10), epidural abscess (n = 1) and unknown (n = 1); Revision cohort: recurrent disc herniation (n = 1), epidural abscess (n = 1), pseudomeningocele (n = 1). Both groups showed significant improvement in all PROMs at the early follow-up (2-12 weeks) and at last follow-up (P < .0001). There was no significant difference in the achievement of MCID (Primary vs revision: 2 weeks 50 vs 55.2%, P = .606; 90 days 62.7 vs 65.5%, P = .774; last follow-up 68.7 vs 65.5%, P = .733). Conclusion: Patients undergoing revision surgery were younger, had lower comorbidity burden and slightly shorter operative times. There was no difference in narcotic consumption, length of stay, or intra-operative and in-hospital complications. Although the revision cohort had a higher rate of complications managed non-operatively, there was no difference in reoperation rates. Both groups showed significant improvement in PROMs, with no difference between groups. These findings suggest that revision MIS microdiscectomy is a safe and as effective treatment option for patients with recurrent herniation, and can provide outcomes equivalent to primary surgery.

Navigation

177

P448: Malposition Rates of Subaxial Cervical Pedicle Screws Placed Using Intraoperative CT (O-arm) Based 3D Navigation

Jonathan N. Sembrano ¹ , Michael Brush ² , Kenneth Holton ¹ , Christopher Martin ¹ , Matthew Hunt ³ , Ann M. Parr ³ , David Polly ^{1 3} , and Robert Morgan ⁴

¹ University of Minnesota, Department of Orthopaedic Surgery, Minneapolis, USA

² University of Minnesota, Medical School, Minneapolis, USA

³ University of Minnesota, Department of Neurosurgery, Minneapolis, USA

⁴ Saint Louis University School of Medicine, Department of Orthopaedic Surgery, St. Louis, USA

Introduction: Cervical pedicle screws (CPS) are biomechanically superior to other spinal fixation anchors; however, placement is technically demanding, and screw malposition could have catastrophic consequences. Computer navigation has been shown to improve accuracy rates in thoracolumbar pedicle screw placement. However, there are limited studies on use of navigation for placing CPS. We report accuracy rates of computer navigated (CN) CPS placement in a single institution. Material and Methods: Between Jan 2014 and March 2020, we identified 100 patients who underwent CN CPS placement (C3-C7) and with either postoperative computed tomography (CT) or intraoperative O-arm 3D scan for screw evaluation. Screw position was evaluated in axial, coronal and sagittal planes, and graded as follows: 0 – fully in bone; I –minor breach deemed inconsequential (< 25% of screw width); II – breach that is considered not ideal, but acceptable (25-50% of screw width); III – breach that is considered either dangerous or compromising strength of fixation. Screws that were > 50% outside the pedicle in any direction were considered grade III. Results: 413 CN CPS screws (C3-C7) were placed in 100 patients mean age 56 yrs (range 10-81); M:F = 54:46. Number of fusion levels ranged from 1 to 12. 44 patients had previous cervical spine fusion (29 anterior; 15 posterior). 12 patients underwent proximal extension of previous thoracolumbar fusion. Rates of serious screw malpositions: Gr III = 15/413 (3.6%), combined Gr II/III = 42/413 (10.2%). Breaking down the Gr III screws per level: C3 = 1/33 (3.0%), C4 = 3/63 (4.8%), C5 = 3/72 (4.2%), C6 = 5/85 (5.9%), C7 = 3/160 (1.9%). Breaking down the combined Gr II/III screws per level: C3 = 8/33 (24.2%), C4 = 9/63 (14.3%), C5 = 8/72 (11.1%), C6 = 10/85 (11.8%), C7 = 7/160 (4.4%). Mean screw grade per level: C3 = .88; C4 = 0.67; C5 = .51; C6 = .46; C7 = .26. Using non-parametric rank sum tests with Bonferroni correction, significant differences were noted between the following: C3 vs each of the two most caudal levels (C6 and C7; P = .029 and <.001 respectively); and C7 vs each of the upper 2 levels (C3 and C4; P = .029 and <.001, respectively). Conclusion: Our study shows a 3.6% rate of dangerous/unacceptable (Gr III) screw placement, and 10.2% non-optimal (combined Gr II and III) using intraoperative 3D imaging and computer navigation. Mean screw grade incrementally decreased in a cephalad to caudad direction (C3 to C7), indicating that pedicle breach is more likely at the upper subaxial cervical levels. This also confirms that C7 is the safest level for CPS placement. Our results add to only few other studies that have reported on this technique. To our knowledge this is the biggest study on a uniform technique of navigated pedicle screw placement that included only subaxial levels C3-C7.

194

P449: Dorsal Fusion as Correction of Craniocervical Instability in Patients With Benign and Malignant Lesions Using O-Arm System

Nikolay Mirchev ¹ , Orlin Pavlov ¹ , and Robert Behr ²

¹ Klinikum Fulda gAG, Neurosurgery, Fulda, Germany

¹ Klinikum Fulda gAG, Neurosurgery, Fulda, Germany

Introduction: A prospective analysis of the surgical treatment and results of 157 patients with benign and malignant craniocervical, atlantoaxial and high cervical lesions operated during 8 years period (2011-2018) at our Department was performed. The aim of the analysis was to assess the factors affecting dorsal fusion as correction of craniocervical and atlantoaxial instability. Material and Methods: We analyzed 109 patients with traumatic lesions, 12 patients with inflammatory lesions, 8 patients with degenerative instability, and 27 patients with craniocervical tumors. Results: We performed 162 operations. Because of craniocervical/cervical instability we made posterior screw fixation in all of 157 patients. In order to improve screw placement accuracy we performed intraoperative O-Arm in 138 cases. The operative duration was 2 h. in O-Arm operations and 4.20 h in C-arm operation. The blood loss was 250 ml in O-Arm and 550ml in C-Arm procedures. The mean screw length in C1/C2/C3 vertebras was 30 mm in O- Arm procedures and 24 mm in C-Arm procedures. The most common operative complications were: CSF leak – in 2 cases, postoperative infection – in 7 cases, screw misplacement - in 2 cases (in C- Arm procedures) without early operative mortality. The 24-monts follow-up patients showed good recovery in 108 patients, moderate disabling – 33 patients, severe disabling – 6 patients, vegetative state – 4 patients, death 6 patients with malignant lesions. Conclusions: Early correction of craniocervical and atlantoaxial cervical instability facilitated neurological recovery by preserving the existent neurological function. Using of O-Arm increase significant operative screw placement accuracy, and preserve intraoperative nerve and vertebral artery injury. Recently because of the improvement of neuroimaging techniques, surgical techniques and neurointensive care the results of treatment of these lesions are optimal.

253

P450: Dorsal Stabilization of the Spine With O-Arm as a Part of 360 Degrees Stabilization of the of the Spine

Orlin Pavlov ¹ , Nikolay Mirchev ¹ , Alexa Ruiz ¹ , and Robert Behr ¹

¹ Klinikum Fulda, Department of Neurosurgery, Fulda, Germany

Introduction: With the increasing understanding of spinal pathologies, the number of 360 degrees stabilisation of the spine is growing. The dorsal fusion is often the first step in the circumferential stabilisation of the spine, whereas the O-Arm as a navigation tool plays a very important role. The reported accuracy of screw placement of O-Arm is about 99%. Methods: In our study, there are 25 patients, who underwent a circumferential stabilisation of the spine due to variety of pathologies, including trauma, metastasis, degenerative disease and inflammation on the spine. The dorsal fusion was carried out with O- Arm navigation tool and afterwards the ventral stabilisation was carried whether throughout a laterodorsal approach or throughout a ventral approach. Results: As a total of 184 screws were placed in massa lateralis or in pedicles. Only a single screw had to revised intraoperatively because of misposition. A total of 99,46% accuracy was achieved using the O-Arm navigation tool. Conclusion: Performing a dorsal fusion with O-Arm in 360 degrees stabilisation of the spine represent a very accurate and time-saving tool, in order to achieve a spinal fusion.

567

P451: Pedicle Screw Insertion - An Educational Assessment of Accelerated Learning

Bisola Ajayi ¹ , Mohsen Raza ¹ , Jason Bernard ¹ , Timothy Bishop ² , and Darren Lui ¹

¹ St George's Hospital, Complex spine surgery, London, United Kingdom

² St George's Hospital, London, United Kingdom

Introduction: The correct placement of pedicle screws is a major part of spine fusion and it requires experienced trained spinal surgeons. In the era of European Working Time Directive (EWTD), surgical trainees have less opportunity to acquire skills. Josh Kauffman (Author of The First 20 Hours) examined the K. Anders-Ericsson study that 10,000 hours is required to be an expert. He suggests you can be good at anything in 20 hours following 5 methods. This study was done to show the use of accelerated learning in trainees to achieve competency and confidence on the insertion of pedicle screws. Methods: Data was collected using 3 experienced spine surgeons, 8 trainees and 1 novice (control) on the cadaveric insertion of pedicle screws over a 4 day didactic lecture in the cadaver lab. Each candidate had 2 cadavers and 156 screw placements over 4 hour shifts. Data was collected for time of pedicle screw insertion for each level on the left and right side. A pre-course and post-course questionnaire (Likert scale) was conducted. Results: There were 8 candidates (surgeons) involved. 1 spinal SpR, 6 spine fellows and 1 junior consultant. A physiotherapist was the control novice. The surgeons and the control got significantly faster over time. The control made significantly more errors than the surgeons. Surgeons were significantly faster by the end (P value < .05). The control got faster over time and by the end, was no longer significantly slower than the surgeon when they first started. Conclusion: Pedicle screw insertion can cause significant morbidity, which includes paralysis. As a trainee, this is not an easy skill to acquire or practice. This focused pedicle screw course shows that a junior spinal surgeon can achieve improved competency and confidence in 20 hours but furthermore a complete novice can learn to insert pedicle screws and reach a level of competence almost at the level of the trainee in 20 hours as well.

Keywords

pedicle screw insertion; accelerated learning; spinal surgery

917

P452: Are Minimally Invasive Robotic Guided TLIF More Safe and Accurate Than Freehand Open TLIF

Sasidharan M D S ¹ , Keyur Akbari ¹ , Vighneshwara Badikillaya ¹ , Muralidharan Venkatesan ¹ , and Sajan Hegde ¹

¹ Apollo Hospital, Spine Surgery, ChennaI, India

Introduction: Freehand placement of pedicle screws by exposing the bony landmarks in a midline approach is the most common spinal fusion technique. Minimally invasive approaches have changed with Robotic guidance, which facilitates performing such cases in a percutaneous paramedian approach. We compare one surgeon′s experience with both approaches. Material and Methods: To analyze the perioperative and postoperative outcomes of patients who underwent Robotic guided Minimally Invasive transforaminal lumbar interbody fusion (Robotic MI-TLIF) and open freehand TLIF (O-TLIF) as a control. Several studies have compared Open TLIF to MIS TLIF. However comparing the Robotic MI TLIF to Open TLIF using a single cohort has not been fully explored. We prospectively reviewed patients who underwent Transforaminal Lumbar Interbody Fusion surgery between Oct 2019 - Mar 2020 with a minimum of average 6 months follow up. A total of 32 patients who underwent Robotic guided MI-TLIF (ExcelsiusGPS Robotic Navigation Platform) during this time period were included in the study. A series of consecutive 32 patients who underwent open free hand TLIF during the same time period were used as a control group. T test and χ2 were used to analyze data. P < .05 is considered as statistically significant. Results: 64 patients, 32 Robotic MI-TLIF vs 32 O-TLIF. No differences in age, gender-ratio or BMI were noted between the 2 cohorts. Of the 138 screws placed in the Robotic MI-TLIF 137 (99.2%) were accurate, while O-TLIF had 140 screws of which 134 (95.7%) were placed accurately (P < .0001). Robotic MI-TLIF had blood loss of 63.5ml vs 98.4ml in Open-TLIF (P < .001). Average Hospital stay 1.6 vs 2.4 days Open-TLIF (P < .001). Overall complication rate .98% vs 5.8% O-TLIF. Despite the robotic group being percutaneous and the control group open, the procedure time (134.7 vs 136.4 mins) and utilization of intraoperative fluoroscopy (8.6 vs 8.4 sec) were similar. Conclusion: In comparing Robotic MI-TLIF vs Open TLIF, the Robotic Minimally Invasive procedure demonstrated increased screw accuracy, minimal blood loss, hospital stay and complications. VAS and ODI were similar in 6 months follow-up for both groups.

924

P453: Initial Experience and Learning Curve With the New Excelsius GPS Robotic Navigation Platform in Spine Surgery- A Single Centre Review of 50 Cases

Keyur Akbari ¹ , Vignesh Badikillaya ¹ , Sasidharan M D S ¹ , Muralidharan Venkatesan ¹ , and DR SAJAN HEGDE ¹

¹ Apollo Hospitals, Spine, Chennai, India

Introduction: The field of spine surgery has been revolutionized with the introduction of robotic assisted spine surgery in this century. The present generation of robot can be termed as “cobots” - machines designed to interact and assist humans to make spine surgery safer and more efficient. The study aims to present our initial experience and technical difficulties and learning curve for the first 50 consecutive cases done with the new Excelsius GPS robotic navigation platform. Material and Methods: This is a single surgeon, single-center prospective study carried on consecutive 52 patients who were planned robotic spine surgery with Excelsius GPS robotic navigation system. All patients underwent preoperative high resolution CT scan with the Aquilion One 320 slice CT system with a reduced radiation dose exposure. Screw trajectories were planned as per the pre op CT scan on the robotic console. Robotic software merges the pre op CT scan and intra operative fluoro scans and gives the actual trajectory to work upon for placement of screw. Parameters such as screw accuracy, operating time, blood loss, radiation exposure, complications, technical issues were evaluated. Results: 50 patients with a mean age of 53.2 yrs (Range:13-87 yrs) were operated for various indications as spinal deformities in 5 patients (Adolescent Idiopathic Scoliosis -4, Ankylosing Spondylitis-1), degenerative lumbar canal stenosis single/double level- 37, post-traumatic-4,dorsal stabilization for infection-4.There were 27 females (54%) and 23 males (46%) in the cohort. Forty six patients underwent surgery in prone position and 4 patients underwent surgery in single position lateral for robotic assisted pedicle screw placement. 2 cases which were planned for robotic assisted surgery were converted to open surgery as there was a functionality issue of merging the pre op CT scan with the intra operative fluoro scan as the patient prone position and intraoperative traction in scoliotic child had change the alignment of spine compared to the pre op CT scan.A total of 252 pedicle screws and 6 lateral mass screws were inserted. In the first 10 cases, the average time for screw insertion was 6.4 min/screw which reduced to 3.2 min/screw in the next 20 cases. The average time for screw insertion for the last 20 cases was 2.2 min/ screw which is attributed to proper planning, accustomization to instruments, and skill development. Two screws were misplaced laterally due to skiving which were noted on intraoperative fluoroscopy and were revised with free hand technique without any catastrophic complications. This can be attributed to sligh trajectory change of screw on position of patient with inherent instability. The average blood loss was 180.8 ± 60.3 ml. The average radiation exposure time per screw due to intraoperative fluoro also reduced from an initial 1.5 sec for the first 10 cases to .8 sec for the next 40 cases. The operating time was reduced with each successive case implying attainable learning curve. There were no adverse neurovascular complications. Conclusion: We conclude that robotic assisted spine surgery is safe and accurate and learning curve is gradually established with each subsequent case.

1047

P454: Patient Radiation Exposure From Intraoperative Fluoroscopy CT and True CT in 3D Navigated Spine Surgery

Jacob Goldberg ¹ , Franziska Anna Schmidt ¹ , Fabian Sommer ¹ , Sertac Kirnaz ¹ , Branden Medary ¹ , Lynn McGrath ¹ , and Roger Härtl ¹

¹ New York Presbyterian Hospital/Weill Cornell, Neurological Surgery, New York, USA

Study design: Retrospective case study. Purpose: 3D navigation assisted spinal instrumentation increases accuracy and improves surgical workflow. Workflow changes have allowed for minimization of radiation exposure to operating room staff however patients remain exposed to radiation during intraoperative image acquisition. The effective radiation dose from true intraoperative CT (iCT) and fluoroscopy CT (fCT) remains unclear. Further, iCT can be acquired at lower radiation intensities but may require repeated scans if image quality suffers. Concern about radiation exposure is a source of apprehension among patients undergoing navigated spinal surgery. In this study, we identified the effective patient radiation dose at 50% and 100% radiation level in iCT and the effective dose from fCT. We then compared these doses to data reported in the literature. Methods: We conducted a retrospective, single-center study. Intraoperative navigation CT scans were included from January 2018 through December 2020. Scanner calibration was verified daily. The Radimetrics^TM enterprise platform (Bayer AG, Leverkusen, Germany) was used to obtain patient dose history and pertinent exam details. Results: Forty-nine 100% iCT scans and thirteen 50% iCT scans were included. The median patient dose for 50% iCT scans was 7.7 mSv (5.3 – 16.0 mSv). The median patient dose of the 100% iCT scans was 13.9 mSv (6.6 – 22.9 mSv). Twelve fCT scans were included with a median patient dose found to be 16.2 mSv (5.3 – 22.3 mSv). Conclusion: Lower dose (50%) iCT resulted in a reduced effective radiation dose after acquisition of technically adequate scans for navigation. Further, we demonstrate that the non-reduced iCT and fCT scans are comparable to diagnostic CT scans in terms of effective radiation dose.

1141

P455: Intraoperative-3d Imaging in Multilevel Posterior Spinal Fixation: Does It Prevent Reoperations for Malpositioned Screws?

Clifford Pierre ¹ , Bilal Qutteineh ¹ , Alexander von Glinski ¹ , Dr. Sven Frieler ¹ , Lincoln Jimenez ¹ , Benjamin Schell ¹ , Ryan Goodmanson ¹ , Erik Hayman ¹ , Jeanju Sung ¹ , Sarah Strot ¹ , Rod Oskouian ¹ , and Jens Chapman ¹

¹ Swedish Neuroscience Institute, Neurosurgery, Seattle, USA

Introduction: Identification of malpositioned pedicle screws may not be evident until after surgery and may require secondary revision surgery. Current innovations can improve verification of screw placement using 3-Dimensional 3D) technology. Intraoperative detection and repositioning of malpositioned screws may lower the rate of revision surgery. Methods: A single institution retrospective study was conducted of all patients who underwent multilevel posterior spinal fixation (>3 levels) from 12/2018 to 11/2019 with intraoperative-3D scans (Ziehm 3D C-arm, location). The primary outcome parameters included unplanned return to the operating room due to pedicle screw malposition. Comparisons to institutional collected quality data regarding revision rate for malpositioned screws from 01/2016 to 12/2019 included cost analyses. Results: 114 patients underwent multilevel posterior spinal fixation with intraoperative-3D scans. Mean follow-up was 3 months. Mean age was 64 years (range 27–85); 46 males, 68 females; 1686 screws inserted. After acquiring intraoperative-3D scans, 20 screws (1.5%) were changed in 10 patients (8.8% of cases). There were no intraoperative complications due to malpositioned screws or repositioning. 87 patients had post-operative CT imaging; 14 screws were found to have grade 2 [2-4 mm] breaches which were accepted on intraoperative-3D by the attending surgeon. Patients remained asymptomatic and no patients underwent revision surgery due to malpositioned screws. Our institutional revision rate for malpositioned screws without the use of intraoperative-3D scans was as follow: 2016-2.3%, 2017-.66%, 2018-.39%, 2019-.65%. Conclusions: Intraoperative pedicle screw placement verification with a routine intraoperative-3D scan may be effective in patients undergoing multilevel posterior spinal fixation as it can reduce the secondary revision surgery rate due to malpositioned screws. 

1166

P456: Comprehensive error analysis for robotic assisted placement of pedicle screws in pediatric spinal deformity: the initial learning curve

Kyle Morse ¹ , Madison Heath ¹ , Fedan Avrumova ¹ , Christopher Defrancesco ¹ , Peter Fabricant ¹ , Darren Lebl ¹ , and Roger Widmann ¹

¹ Hospital for Special Surgery, New York, USA

Introduction: Surgical navigation improves pedicle screw insertion accuracy and reliability. Robotic-assisted spinal surgery (RASS) and screw placement has not been fully assessed in pediatric patients with spine deformity undergoing posterior spinal fusion. The purpose of this study was to describe the learning curve for robotically assisted pedicle screw placement in pediatric patients. Material and Methods: We conducted a retrospective review of prospectively collected data on a consecutive series of the first 19 pediatric patients who underwent posterior spinal fusion by a single surgeon using robotic navigation at our center. Demographics, curve parameters, and pedicle morphology were recorded. Screw accuracy was assessed with calibrated postoperative 3-D fluoroscopic images and screw trajectory was compared to the pre-operative planning template. Location and magnitude of all breaches were recorded. All complications of planned and placed robotically placed screws were recorded. Results: 19 pediatric patients with an average age of 14.6 ± 2.2 years and spine deformity. There were 4 males and 15 females. 194 left-sided screws were planned as robot assisted. 168 of the robotically planned screws (86.6%) were placed with robot assistance; 29 robotically planned screws (15.0%) were ultimately placed freehand. The mean time per robotically placed screw was 3.6 ± 2.4 minutes. There was an overall significant effect of vertebral level on screw time (P = .006) with screw times at the T2-T3 vertebrae accounting for the longest time (P < .05). A total of 15 breaches (8.9%) and one anterior perforation occurred throughout the series. This series had 2 critical (>2–4 mm) breaches, one was associated with a durotomy, and both occurred in the first case. Six breaches alone occurred in the first case and 11 of the breaches occurred over the first 8 cases. There were no intraoperative/postoperative neuromonitoring changes and no sequela from the durotomy. Smaller pedicle diameter was associated with decreased robotic screw accuracy (p < .001) and increased risk for medial breach (P = .002). Compared to the pre-operative template, screws that were not placed accurately (compared to preoperative planning software template) had a 21.7% breach rate. There was a significant improvement in accuracy following the first 10 cases (66.2% vs 84.4%, P = .011). Conclusion: There was significant improvement in screw time and accuracy and most importantly decreases in the number of breaches after 10 cases. Caution should be exercised during the initial training period to avoid complications as experience and training lead to an improved understanding of surgical planning, robotic usage, and usage and avoidance of operator directed complications.

1349

P457: Comparative Radiographic Analysis and Clinical Outcomes Between o Arm Navigated and Fluoroscopic Guided MIS-LIF

Weerasak Singhatanadgige ¹ , Worawat Limthongkul ² , Vit Kotheeranurak ³ , and Wicharn Yingsakmongkol ²

¹ Faculty of Medicine, Chulalongkorn University, Orthopedics, Bangkok, Thailand

² Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand

³ Queen Savang Vadhana Memorial Hospital, Orthopedics, Bangkok, Thailand

Introduction: The differences in clinical and radiographic outcomes between NAV and FLUO MIS-TLIF are currently unclear. This study aims to compare the clinical and radiographic outcomes of 3D computer navigation (NAV) and fluoroscopic-guided (FLUO) minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF). Furthermore, we determined a correlation between radiographic findings and predictable clinical outcomes. Material and Methods: Between January 2016 and October 2018, 97 consecutive patients who had undergone MIS-TLIF with lumbosacral degenerative disease in our institute were retrospectively reviewed. Radiographic outcomes (angle of screw convergence, screw-to-pedicle diameter ratio, %screw depth, screw penetration, %fusion, facet joint violation) were analyzed by two independent orthopedists using thin-slice computed tomography. Clinical outcomes were assessed with Oswestry Disability Index (ODI), Visual Analog Scale (VAS), and satisfaction score. The association between radiographic and clinical outcomes was then analyzed to determine predictable variable outcomes. Results: We compared 61 patients (270 screws) in the FLUO group and 36 patients (172 screws) in the NAV group. The NAV group showed a significantly higher %screw depth (89.04 ± 6.07% vs 85.18 ± 7.54%; P = .011), larger angle of screw convergence (27.7 ± 3.93° vs 18.44 ± 7.54°; P < .001), lower incidence of pedicle penetration (0% vs 3.7%; P = .016), and less facet joint violation (1.0% vs 8.1%; P = .003). The clinical results revealed a significantly better VAS and ODI in the NAV group at 6 and 12 months. The %screw depth correlated with the VAS back pain score at the 12-month follow-up. Conclusion: NAV MIS-TLIF showed superior screw placement accuracy, better screw convergence and depth, and lower cranial facet joint violation than FLUO MIS-TLIF. Furthermore, better clinical scores were revealed in the NAV group at the 6- and 12-month follow-ups.

1845

P458: Peri-Operative Outcomes of Intra-Operative Skull Femoral Traction (ISFT) and Navigation Sequential Drilling (NSD) for the Management of Neuromuscular Scoliosis in Cerebral Palsy Patients

Marina Rosa Filézio ¹ , Ravindra Singh ¹ , David Parsons ¹ , Lasantha Gunasekara ² , and Fabio Ferri-de-Barros ¹

¹ Alberta Children’s Hospital, CALGARY, Canada

² University of Calgary, Calgary, Canada

Introduction: Scoliosis in cerebral palsy (CP) is a challenging problem. The incidence of scoliosis among children diagnosed with cerebral palsy is reported from 15 to 75%. Higher rates of complications have been reported for posterior spinal instrumentation and fusion (PSIF) procedures done in cerebral palsy patients. Reported complications include mortality, infection, increased hospital stay, revision surgery, excessive bleeding, blood transfusion. Prolonged surgical time, excessive bleeding, preoperative nutritional status, concomitant systemic infections (urinary, pulmonary) have been associated with increased rate of infection. In this study we propose to investigate whether, use of intra-operative skull femoral traction (IOSFT) and navigated sequential drilling (NSD) in posterior spinal instrumentation and fusion (PSIF) among patients with CP and scoliosis has made any significant change in terms of operative time, blood loss, blood transfusion rate, the cost of surgery and length of hospital stay. Material and Methods: retrospective single centre observational cohort study at the Alberta Children’s Hospital (ACH). Criteria for Inclusion of Subjects: Cerebral palsy (CP) Patients with Scoliosis who have undergone single stage posterior spinal instrumentation and fusion (PSIF) at our institution from 2008 to 2020. Criteria for Exclusion of Subjects: Patients with scoliosis of other etiology, patients who had an anterior or combined approach, patients undergone revision surgery, patients with any systemic disease(s) and patients who had received preoperative autologous blood donations will be excluded. Results: 1. Collect demographic data related to the patients including age, sex, diagnosis and GMFCS (gross motor function classification). 2. Pre-operative and post-operative radiographs to assess curve magnitudes, Lenke type, curve correction, number of levels fused, implant density, sagittal plane balance and coronal plane balance. 3. Data related to pre-operative haemoglobin, operative time (skin to skin time or from application of skull femoral traction to their removal at the end of the procedure), intra-operative blood loss, need for an extended OR time, requirement for peri-operative blood transfusion, length of hospital stays, total cost per surgery (CAD). Case cost will be calculated based on provincial fee codes, institution’s OR database, average bed cost, average provincial nursing salary, and the Canadian Blood Services and Transfusion Medicine costs. Conclusion: As described in the previous study the use of IOSFT and NSD significantly curtailed operating time, blood transfusion requirement length of hospital stay (LOS) and cost of surgery for idiopathic patients. These are important variables determining success of any surgical technique. If the same outcomes are reflected in this study then the use of IOSFT and NSD would become a significant surgical tool for neuromuscular scoliosis. Surgical time, blood loss and LOS play important role in deciding infection rate in neuromuscular scoliosis patients and any intervention reducing these variables would be expected to have a positive impact on this. Furthermore, secondary outcomes of the surgery will add to the primary outcomes in terms of correction achieved and effect of GMFCS grade on all the surgical outcomes.

1878

P459: Use of 3-D Navigation for En Bloc Resection of Sacral Chondrosarcoma

Álvaro Soteres ¹ , Pierluca Zecchetto ² , Manuel Valencia Carrasco ² , and Luis Bahamonde ²

¹ Hospital Clinico Mutual de Seguridad, Santiago, Chile

² Cinica Alemana Santiago, Santiago, Chile

Introduction: Chondrosarcoma is a malignant cartilaginous matrix lesion that represents 25% of primary malignant bone tumors. It has a 5-year survival of 70%. The spine is the segment where it occurs most frequently. About 20% of spinal chondrosarcomas occur in the sacrum, usually eccentrically with sacroiliac compromise. Since it is a chemo and radioresistant tumor, en bloc resection is essential. Despite this, the recurrence can be as high as 20%. Considering the importance of obtaining adequate margins and the high risk of perioperative complications given the complex anatomy of this region, careful preoperative planning, including intraoperative navigation use is paramount. Method: Case report. A 41-year-old woman suffering polyarthralgia consulted for a bone scan finding of a lesion in the sacrum. This study was complemented with a computed tomography and magnetic resonance that showed an eccentric tumor at the left in S2 and S3 levels without sacroiliac involvement. The biopsy revealed grade 2 chondrosarcoma. Surgical planning is carried out by combining CT and MRI images, defining tumor mass, involvement in the emergence of nerve roots at the level of left S1 and S2 and margins free of tumor to be resected. Preoperative left lateral sacral and middle sacral artery embolization were done. With intraoperative 3 D navigation system en bloc resection was performed according to the preoperative plan. S1 a S2 nerve roots were preserved. Incidental durotomy in a Tarlov cyst was repaired. Results: No neurological impairment nor sphincter dysfunction occurred in postoperative follow up. Cerebrospinal fluid fistula required surgical revision. According to the pathological anatomy analysis, tumor free margins were achieved. Conclusion: Sacral chondrosarcoma is a rare tumor, which is highly resistant to radiation and chemotherapy. For this reason, surgery is the cornerstone in the treatment of these patients. En bloc resection with wide margins is the surgery of choice and the main goal of treatment. To comply with this, it is mandatory to perform an accurate surgical planning supported by an image integration system, which allows us to adequately define the segment to be resected. In order to achieve all of the above and to reduce the risk of complications, the intraoperative navigation system is a tool that should be used whenever possible, since it optimizes the treatment offered and favors better results for patients.

1886

P460: The Feasibility of 3D Intraoperative Navigation in Lateral Lumbar Interbody Fusion: Perioperative Outcomes, Accuracy of Cage Placement and Radiation Exposure

Hikari Urakawa ¹ , Ahilan Sivaganesan ¹ , Avani Vaishnav ¹ , Evan Sheha ¹ , and Sheeraz Qureshi ¹

¹Hospital for Special Surgery, New York, USA

Introduction: Intraoperative navigation (ION) has been widely used in posterior spine surgery. However, few studies have reported the use of ION in lateral lumbar interbody fusion (LLIF) and, to our knowledge, there are no comparative cohort studies, compared to conventional 2D fluoroscopy only. Thus, the safety and accuracy of interbody placement remain unclear. The aim of this study was to evaluate the perioperative outcomes, accuracy of cage placement and radiation exposure in LLIF using 3D ION, compared to conventional 2D fluoroscopy only. Material and Methods: Patients who underwent LLIF for degenerative pathology by a single surgeon were included in this study. The perioperative outcomes and accuracy of cage placement were examined in all patients who underwent LLIF using ION (ION group) or fluoroscopy only (non-ION group). The radiation exposure was examined only in patients who underwent stand-alone LLIF. Results: A total of 87 patients with 154 levels (49 patients with 79 levels in the ION group and 38 patients with 75 levels in the non-ION group) were included in this study. The mean number of levels was 1.61 in the ION group and 1.97 in the non-ION group (P = .102). There were no significant differences in operative time (ION 143.5 min vs non-ION 126.0 min, P = .406), time from induction end to surgery start (ION 31.0 min vs non-ION 31.0 min, P = .761), estimated blood loss (ION 37.5 ml vs non-ION 50.0 ml, P = .351), perioperative complications (ION 22.4% vs non-ION 15.8%, P = .587) and length of stay (ION 50.6 hours vs non-ION 41.7 hours, P = .841). There was no significant difference in the accuracy of cage placement (P = .279). Radiation exposure also did not significantly differ between the ION group and the non-ION group (ION 51.0 mGy vs non-ION 47.4 mGy, P = .237). Conclusion: The perioperative complication profile, accuracy of cage placement and radiation exposure of LLIF using ION were comparable to those using only traditional fluoroscopic techniques. The use of ION in LLIF, which has been shown to be a feasible, safe and accurate technique, may have the added benefit of providing improved understanding of three-dimensional anatomy.

1888

P461: Augmented Reality Spine Surgery: Evaluation of Pedicle Screw Placement Accuracy in Consecutive Patients Undergoing Instrumented Spinal Fusion Using the Augmedics Xvision Spine System

Ethan Cottrill ¹ , Ann Liu ¹ , Zach Pennington ¹ , Jeff Ehresman ¹ , Majid Khan ² , Sheng-fu L. Lo ¹ , Daniel Sciubba ¹ , Timothy F. Witham ¹ , and Camilo Molina ³

¹ Johns Hopkins University School of Medicine, Department of Neurosurgery, Baltimore, USA

² Thomas Jefferson University Hospitals, Department of Radiology, Philadelphia, USA

³ Washington University School of Medicine, Department of Neurosurgery, St. Louis, USA

Introduction: Augmented reality via head-mounted display (AR-HMD) recently garnered FDA 510(k) approval for pedicle screw placement. In contrast to other computer-assisted navigation modalities, AR-HMD projects navigation data directly onto the operator’s retinae using a transparent near-eye-display headset, thereby eliminating the need to shift attention to a remote display. Both 2-dimensional (i.e., axial and sagittal projections of tracked-tool trajectory) and 3-dimensional (i.e., computer-rendered bony spine anatomy overlaid onto the real spine anatomy) navigation data are displayed via the AR-HMD. The objective of the present study was to assess the accuracy of pedicle screws that were placed using AR-HMD in the first ten consecutively treated patients at our institution. Material and Methods: This is a single-center retrospective review of the accuracy of pedicle screw placement in the first ten consecutive patients in whom pedicle screws were placed using AR-HMD (xvision™ Spine System, Augmedics; Chicago, IL). Following institutional ethics approval, patients were prospectively enrolled and followed beginning in June 2020. Inclusion criteria were age >18 years, any surgical indication requiring instrumented thoracic and/or lumbosacral fusion, and study consent. Pedicle screws were placed using AR-HMD by three spine fellowship-trained attending neurosurgeons. Patient demographic and surgical characteristics were recorded from the electronic medical records. The primary endpoint was the accuracy of pedicle screw placement, which was assessed via the Gertzbein-Robbins classification system by a neuroradiology fellowship-trained attending radiologist. Using this classification system, pedicle screws with scores of “A” or “B” were considered to be placed accurately. Pedicle screw placement accuracy was calculated by dividing the number of pedicle screws that were placed accurately by the total number of pedicle screws that were placed. Results: The first ten consecutive patients (mean age: 64.9 ± 13.9 years; 7 females and 3 males) in whom pedicle screws were placed using AR-HMD were reviewed. Mean body mass index was 28.1 ± 5.3 kg/m². Surgical indications were degenerative (7), trauma (1), and tumor (2). Four patients had prior spine surgery, including one with decompression alone and three with instrumented fusion. All ten patients presented with back pain, and six presented with radiculopathy. Radiological spine findings included disc herniation (3), foraminal stenosis (1), fracture (1), lumbar spondylolisthesis/stenosis (4), proximal junctional kyphosis (1), and thoracic kyphosis (1). A total of 74 pedicle screws were placed using AR-HMD, including 30 in the thoracic spine and 44 in the lumbosacral spine. In the thoracic spine, accuracy of pedicle screw placement was 96.7% (29/30); the inaccurately placed pedicle screw, which did not produce clinical sequelae, was at T5 and received a score of “C” in a patient presenting with thoracic kyphosis. In the lumbosacral spine, accuracy of pedicle screw placement was 100% (44/44). Across all levels, accuracy of pedicle screw placement was 98.6% (73/74). Conclusion: In this study of the first ten consecutive patients in whom pedicle screws were placed using AR-HMD by three spine surgeons at a single institution, accuracy of pedicle screw placement was 98.6% (73/74 screws). These early data suggest that pedicle screw placement using AR-HMD is safe and effective in the thoracolumbosacral spine.

1893

P462: A Review of Time-Demand, Radiation Exposure and Outcomes of Skin-Anchored Intra-Operative 3d Navigation in Minimally Invasive Posterior Cervical Laminoforaminotomy

Avani Vaishnav ¹ , Philip Louie ² , Hikari Urakawa ¹ , Kosuke Sato ³ , Sravisht Iyer ¹ , Steven McAnany ¹ , Todd Albert ¹ , Catherine Himo Gang ¹ , and Sheeraz Qureshi ¹

¹ Hospital for Special Surgery, New York, USA

² Virginia Mason Medical Center, Seattle, USA

³ University of Tsukuba, Tsukuba, Japan

Introduction: Intra-operative 3-dimensional navigation (ION) is increasingly being utilized. Studies have shown effective early adaption and radiation reduction with skin-anchored ION in minimally invasive lumbar surgery. However, the novel use of a non-invasive skin-anchored tracker has not been described for cervical surgery. Thus, the purpose of this study was to describe the time demand, radiation exposure and outcomes skin-anchored ION in minimally invasive posterior cervical laminoforaminotomy (MI-PCLF). Material and Methods: A retrospective review of all patients who underwent MI-PCLF by a single surgeon from Apr’17-Nov’19 was performed. Time for ION set-up, operative time, estimated blood loss, radiation exposure, complications and length of stay were evaluated and summarized using descriptive statistics. Results: 21 patients (36 levels) with a mean age of 55 yrs, BMI of 27 kg/m², and comprising 17 (81%) males were included. A majority of cases were 1- or 2 -level (90.5%). The operative levels were: C3C4 (11.1%), C4C5 (19.4%), C5C6 (22.2%), C6C7 (25%), C7T1 (22.2%). Time for ION set-up (induction end to start of the surgical procedure) was a median of 34 minutes [IQR 30-37]. This accounts for patient positioning, prepping and draping, placing the tracker and acquiring a 3D image. Total fluoroscopy time was a median of 10 seconds [IQR 9-11], almost entirely attributable to ION image-acquisition; radiation dose was a median of 2.5 mGy [IQR 1.8-4.9]. Thus, radiation exposure to the patient was minimal. Since OR personnel are behind a protective lead shield during ION image-acquisition, radiation exposure to the surgeon and OR team was negligible. 1 patient required a repeat ION spin, resulting in the fluoroscopy time for ION image-capture being 20 seconds. In 2 patients, ION was abandoned and the procedure was completed using fluoroscopy. Additionally, one patient had a radiation dose of 13.9 mGy, which is almost 3 times the 75^th percentile dose. Although the exact reason could not be determined, this may be attributable to a number of factors including higher dose settings, difference in C-arm position, calibration error, etc. Operative time was 62 mins [IQR 53-74] and estimated blood loss was low (25 ml [IQR 25-25]). There were no wrong level surgeries, or any intra or post-operative complications. Median post-operative length of stay was 6 hrs [IQR 4.4-20.9], with 66.7% of patients being discharged on the day of surgery. Conclusion: The results of our study suggest that ION using a skin-anchored tracker for MI-PCLF is a feasible, safe and accurate technique, resulting in short operative times and minimal complications. Further, it results in negligible radiation exposure to the OR team and low radiation exposure to the patient.

Nonoperative Clinical Treatments

118

P463: Functional Outcome Comparison of Inter-Laminar Epidural Steroid Injection in Different Levels of Lumbar Disc Herniation - A Retrospective Study of 1000 Patients

Shaffaf Kareem ¹

¹ Manipal Hospitals HAL Airport Road Bangalore, Spine Care Department, Bengaluru, India

Introduction: Epidural steroid injections (ESIs) were being employed as a treatment for radiculopathy since they were instigated around 60 years ago. Numerous studies were conducted on this subject and its efficacy is still controversial. In our set up, ESIs are regularly used to support non-operative treatment for LBP and our anecdotal impression is that considerable patients report substantial pain relief after this method and this, in turn, saves health care costs. Our study is aimed at finding the short and medium-term functional outcome comparison of ESI in different levels of lumbar disc herniation (LDH). Material and Methods: A prospective study was conducted from January to December 2019 in 1000 consecutive patients with disc herniation. They were divided into 4 groups: group-A: L3-L4 level, group-B: L4-L5 level, group-C: L5-S1 level, and group-D: multi-level disc-herniation. All patients were given epidural injection prepared with Triamcinolone (80 mg), Bupivacaine (.25% 4 ml) and normal saline (4 ml). Patients were evaluated using numerical rating scale (NRS) immediately, 7 days and 3 months after the injection. When the symptoms of patients did not resolve after giving injection, they underwent surgery. Results: The average age of the study population was 41.8 (range: 20-80) years with a minimum follow-up of 3 months. There were 112, 484, 316, and 88 patients in groups A, B, C&D respectively. Males were found to be more in all the groups. Mean NRS back pain scores and leg pain scores reduced significantly in all groups, more so in group B than others. We found that in group A, B, C, and D patients, 22 (19.65 %), 44 (9.09%), 54 (17.08%), and 34 (38.63 %) respectively underwent surgery. Only one patient suffered from paresthesia for 6 hours post injection, two patients had post-dural puncture headache which was managed with blood patch, while the rest had no complications. Hence there was significant satisfactory outcome in the groups with B (90.9%) >C (82.99%)> A (80.35%) >D (61.36%). Conclusion: ESI causes significant improvement in back and leg pains in patients with any level of disc herniation, but more so in L4-L5 level. However, the short and medium term efficacy of ESI in multilevel disc herniation group was lesser than that of single level disc herniation groups.

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P464: Strengthening Exercises as Treatment for Chronic Non-Specific Low Back Pain: a Comparative Study Between Resistance Training With or Without Use of Weight Equipment

Camila Teixeira de Oliveira ¹ , Michel Kanas ¹ , Nelson Astur ² , Delio E. Martins ³ , and Marcelo Wajchenberg ¹

¹ Federal University of Sao Paulo, Ortopedia, Sao Paulo, Brazil

² Santa Casa de Sao Paulo, Sao Paulo, Brazil

³ Universidade Anhembi Morumbi, Sao Paulo, Brazil

Introduction: Core muscles disfunction contributes with symptoms persistence in patients with chronic low back pain. There are strong evidences in literature, that an active approach, with strengthening exercises has positive effect in rehabilitation of these patients. However, there are many uncertainties regarding which modality or method is more effective. The objective of the study was to analyze and compare the impact in quality of life, function, flexibility, abdominal strength and abdominal fat rate, in patients with non-specific chronic low back pain after eight-week training program using two different exercise programs. Material and Methods: Thirty individuals, between 18 and 65 years-old, participated in the study. Twenty performed physical training program twice a week for 8 weeks, and ten didn’t make any physical exercises, but received orientation and analgesics. The twenty physically active individuals were divided in two groups, and received resistance training prescription, focusing on the same muscles. Ten performed the resistance training with bodybuilding machines and dumbbells and ten didn’t use any weight equipment. All groups were assessed before and after the intervention, answering questionnaires to measure quality of life and function; and physical evaluation that included tests for flexibility, abdominal strength and abdominal fat rate measurement. Results: When comparing the baseline evaluation with 8 weeks, there were no significant differences in both groups for quality of life. All groups showed significant function improvement, including control group; but the resistance training without equipment, was the most evolved group in this regard. For flexibility and abdominal strength gain, just the physically active groups presented significant gains, with superiority for the resistance training using weight group, in both instruments. For abdominal fat rate decrease, just the resistance training using weight group showed significant improvement. When comparing the two exercise programs, there were no significant differences for the evaluated outcomes. Conclusion: The exercise programs were effective for improving function, flexibility, and abdominal strength. Just the resistance training using weight group, also decreased abdominal fat rate. Comparing the tested modalities, there were no statistically significant differences.

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P465: Different Concepts of Bracing in Adolescent Idiopathic Scoliosis (AIS), a Systematic Review and Meta-Analysis

Lorenzo Costa ¹ , René Castelein ¹ , and Moyo Kruyt ¹

¹ UMCU, Orthopedics, Utrecht, The Netherlands

Introduction: Scoliosis is a thoracic deformation with a life-long burden. It has a prevalence of .47-5.2% in the general population. Management of scoliosis mostly depends on the magnitude of the spinal curvature. Observation is indicated for mild curves and brace treatment is normally indicated in curves with a coronal Cobb angle between 25 and 45-50°. SOSORT affirms that optimal inclusions consist of: age 10 years or older, primary coronal curve angle 25-40°, no prior treatment, Risser stage 0-2, premenarche or less than one year postmenarche. As of yet, the application of many different brace concepts and specific brace types, such as full-time, part-time and nighttime braces as well as rigid and soft braces, have been described in the literature. They all apply different degrees of external corrective forces to the trunk to correct the complex 3-D spinal and thoracic deformity. Furthermore, due to the development of multiple braces and non-standardized criteria (such as in- and exclusion criteria and definitions of successful treatment), it is difficult to compare the results. Nevertheless, many studies report on bracing and provide insight in effectiveness. The primary aim of this study is to compare, wherever possible, the effectiveness of the different brace concepts. Effectiveness is defined as the effect on curve magnitude and/or prevention of the need of surgery. The secondary aim is to define the influence of skeletal maturity on brace effectiveness. Material and Methods: This systematic review and meta-analysis was performed according to the PRISMA statement and it is registered at PROSPERO with the ID CRD42020157636. All original studies on brace treatment for AIS were systematically searched for in PubMed and EMBASE up to December 2019. Articles that did not report on any maturity parameter of the study population were excluded. Critical appraisal was performed using MINORS. Brace concepts were distinguished based on prescribed wearing time and rigidity of the brace: full-time, part-time and night-time, rigid braces and soft braces. In the meta-analysis, success was defined as ≤5° curve progression during follow-up, and success rates were compared to untreated scoliosis patients. Results: 31 out of 2487 articles were included. 19 papers showed high risk of bias and 12 medium risk of bias. In the meta-analysis, rigid full-time brace had on average a success rate of 76%, night-time of 73%, soft braces of 63%, observation only of 51%. There was insufficient evidence on part-time, rigid braces for the meta-analysis. Conclusion: The majority of studies focusing bracing of AIS have significant risk of bias. No significant difference between the night-time, or full-time concepts could be identified. Soft braces have a lower success rate compared to rigid braces. Reported success rates are dependent on skeletal maturity at initiation of the treatment.

1627

P466: Rising Needle Sign During Facet Injection. A Useful Sign in Helping Localising of Facet and Reducing Radiation Exposure

Samir Sakka ¹

¹ Al Balqa Applied University, Surgery, Salt, Jordan

Back pain is a common problem affecting general population. Conservative treatment is the main method. Facet injection is an integral part of this conservative treatment. Lumbar facet injection can be carried out under florescent radiography, CT Scan guided or recently under ultrasound. Several attempt often needed to achieve the localising required by operator prior to injection whether using intra-articular or peri-articular technique. This meant even in the expert hand increased radiation exposure to both patient and operator. In the case when ultrasound is used there is an increase in time and pain or discomfort to the patient with every additional localising attempt. This is more evident for new operators and trainees. We describe the Rinsing Needle Sign which help the operator reduce number of attempt in localising the needle, the time needed to do so and the radiation exposure to patient and operator. Facet joint pain contributes significantly to lower back pain. Image intensifier x-ray guidance is used to locate the facet joints. Radiologically there are two recognized approaches for facet injection; The ‘scotty dog’ and the AP views with no significant difference between the two views approaches (Al Tawel et al). There is also two approaches described for the injections to treat facet joint pain. The first and more commonly used one is the medial branch block. The other is direct facet joint block. We use the direct fact injection and its capsule. With regards to visualisation of the facet joint itself, the target point will be the midpoint of the silhouette of the joint cavity. If this is not visualised, it could be either due to the destructive arthritic process or mal position of the x-ray beam (Al Tawel et al; Peh WCG). We use the AP view utilising method on the image intensifier. Having observed the rising needle during localisation of the facet on the AP view we set to confirm this by studying the model and surgical anatomy to explain the sign. After detail anatomical consideration the author used the sign during the procedure and noticed a 45 % reduction of time usage of the Image intensifier exposure when more than one facet is injected using two needles simultaneously. The Rising Needle Sign is a very useful sign in helping localising the facet during needle placement. In our experience this has reduced the exposure time and procedure time significantly. This be will also especially useful for novice and infrequent user helping them in reducing radiation and operative time.

References

1. Al-Tawil K, D. Lopez, M. Blackman, and S. Suresh^. Oblique “Scotty dog” versus antero-posterior (AP) views in performing x-ray guided facet joint injections J Clin Orthop Trauma. 2018 Mar; 9(Suppl 1): S145-S148. Published online 2017 Oct 31.doi: 10.1016/j.jcot.2017.10.010

2. Peh WCG Image-guided facet joint injection Biomed Imaging Interv J. 2011 Jan-Mar; 7(1): e4.Published online 2011 Jan 1.doi: 10.2349/biij.7.1.e4

1686

P467: Pre-Surgical Psychological Screening (PPS) in Spine Surgery. Indian Surgeon's Perspective

Tejasvi Agarwal ¹ , Alok Jain ¹ , and Gajendra Pawal ¹

¹ The Spine Foundation, Mumbai, India

Introduction: Pre-Surgical Psychological Screening (PPS) in general can be used to: 1) determine a patient’s prognosis; 2) develop a customized treatment plan. For patients undergoing back surgery, PPS can be used for 1) Assuring correct diagnosis, 2) To identify those at risk for poor outcome; 3) And to provide effective treatment and follow-up services. Aims: 1) To estimate the prevalence of use of PPS among spine surgeons/neurosurgeons and Orthopedics surgeons doing spine surgery in India. 2) To identify subsets of patients associated with the use of PPS. 3) To evaluate surgeons opinion of PPS and their belief regarding the effect it will add to their practice. Material and Methods: An online survey invitation was sent to 310 surgeons doing spine surgery. Questions addressed surgeon’s characteristics (number of years in practice), practice characteristics (practice type), inclusion of integrated rehabilitation and psychological services, and use of PPS. Impact of psychological factors on rehabilitation and recovery was assessed using an 11-point Likert scale (0, no impact; 10, highest impact). Results: 67 surgeons responded to the survey. Only 16% used Pre-Surgical Psychological screening before surgery. 90% among these were from institutional practice or with experience more than 15 years. Surgeons reported a strong belief that if they use PPS in their practice it will have effect on pain relief (mean impact rating, >7.0); Surgeons also reported a strong belief that if they use PPS in their practice it will have effect on mean of return to work (mean impact rating, >7.0); Analysis of the 67 (21%) responses was done using chi-square test (significance, P < .05). Conclusion: Only minority of surgeons is using PPS in their practice. Surgeons who weren't using or less likely to use PPS were those who have just completed residency/fellowship or begun practice within 5 years. With strong belief among the surgeons for the advantages of using PPS in their practices (mean rating >7), we advocate use of PPS in spine surgery.

1719

P468: Pregnancy Stress Fracture of the Sacrum, About a Case and Review of the Literature

Achraf Lajmi ¹ , Mohamed Ben Jemaa ¹ , Mohamed Ghorbel ¹ , Khaled Keskes ¹ , Tarak Bardaa ¹ , Moez Trigui ¹ , Mohamed Zribi ¹ , Wassim Zribi ¹ , and Hassib Keskes ¹

¹ Habib Bourguiba University Hospital of Sfax, Tunisia, Orthopedic Surgery and traumatology Department, Sfax, Tunisia

Introduction: Stress fractures of the sacrum represent a rare lesion. They are most often reported in athletes who walk and run long distances. Only few cases have been observed in women pregnant in the last trimester of pregnancy or postpartum. Through an observation of stress fracture of the sacrum without osteoporosis occurred in the last trimester of pregnancy, we try to present etiopathogenic and diagnostic peculiarities and therapeutic modalities of this pathology. Material and Methods: A 34-year-old pregnant woman, gynecologist without pathological history, consulted for buttock mechanical intense pain associated with a lameness when walking. Pain started at 38 weeks and three days of amenorrhea without trauma. She was pregnant at term with a well-followed pregnancy and normal course. The interrogatory did not find pelvic-spinal pain during pregnancy, no personal medical-surgical or familial history, especially osteoporosis, no concept of smoking or alcoholism and no history of old trauma or pelvic surgery. The pain was attributed to pregnancy sciatica and the patient was put on analgesics without resorting to any radiological exploration. The patient gave birth by caesarean section for scarred uterus and premature rupture of membranes. The postoperative follow-up was straightforward despite the persistence of the symptomatology. A radiological check-up was requested. The x-rays of the pelvis and dorsolumbar spine were normal. Bone densitometry was normal. MRI of the pelvis showed a vertical fracture of the right sacral ala passing through the sacral foramina S1, S2. The bone scintigraphy showed linear hyperfixation at the level of the right sacral ala. The patient was put on analgesics, vitamins-calcium supplementation and strict bed rest. Results: Evolution was favourable at three months with complete indolence and normal walking. The radiological control by a CT scan of the pelvis showed fracture’s consolidation. Conclusion: Fractures of the sacrum during pregnancy or during postpartum are rare lesions and most often unknown to practitioners. They pose a problem of differential diagnosis with lumbar and sacral damage treated symptomatically and without having use of radiological exploration. MRI is the exam of choice to highlight the diagnostic. The treatment is most often conservative with good results. Respect of the rules of healthy lifestyle with balanced food, regular physical activity as well as good monitoring of pregnancies can prevent the appearance of bone fragility and reduce the risk of these fractures.

1785

P469: Pott's Disease of the Upper Cervical Spine, About a Case and Literature Review

Mohamed Ben Jemaa ¹ , Anis Abdelhedi ² , Mohamed Ghorbel ¹ , Yassine Gdoura ² , Achraf Lajmi ¹ , Wassim Zribi ¹ , Mourad Aoui ¹ , Kamel Ayedi ¹ , and Hassib Keskes ¹

¹ Habib Bourguiba University Hospital of Sfax, Tunisia, Orthopedic Surgery and traumatology Orthopedic Surgery Department, Sfax, Tunisia

² Habib Bourguiba University Hospital of Sfax, Tunisia, Neurosurgery Department, Sfax, Tunisia

Introduction: Pott's disease is still a common pathology in countries with adverse socioeconomic conditions. Usually, it is located at the dorso-lumbar spine. The sub-occipital localization is very rare. We present an observation of this localization in order to identify its neuro-radiological particularities and therapeutic modalities. Material and Methods: A 19-year-old patient, with no particular pathological history, had presented neck pain for 2 months, not improved by analgesic treatments. The neurological examination found a cervical spinal syndrome. The erythrocyte sedimentation rate (ESR) was 80 at the 1st hour. The standard cervical spine x-ray showed an atloido-axoid dislocation. The CT scan showed a lytic process at the axis with posterior wall recession and a collection compressing the marrow. The cervical MRI confirms the total destruction of the body and the lateral masses of the axis associated with a large collection on the C1 C2 stage producing true epiduritis. The Koch's bacillus was isolated by surgical biopsy (transoral) of prevertebral lesion. The patient was treated with thoraco-cervical immobilization (for 7 months) and anti-tuberculosis drugs (for 12 months). Results: One year later, we note on the control CT scan a good bone reconstruction and on MRI a disappearance of epiduritis. Clinically, the patient presents no complaints. Conclusion: Pott's disease of the upper cervical spine is a very rare condition. Diagnosis is usually late at the stage of neurological deficit. It should be considered in front of a chronic torticollis associated with a pre-vertebral thickening and a lysis of C1C2 on the x-ray. MRI is of great diagnostic value and allows monitoring of the forms treated. The diagnosis must be early. It is confirmed on histological and bacteriological arguments but sometimes retained on elements of presumption. Treatment is based on anti-tuberculosis antibiotics and immobilization of the cervical spine. The course with treatment is usually favorable.

1846

P470: Comparison of Clinical Outcomes of Unguided Versus Ultrasound Guided Sacroiliac Joint Infiltration in SI dysfunction Related Back Pain - A Randomized Control Study

Jitesh Manghwani ¹ , and Harvinder Singh Chhabra ¹

¹ Indian Spinal Injuries Center, New Delhi, India

Introduction: Scope and relevance:

• USG guided and fluoroscopy guided injections are the standard techniques in SI joint infiltration. However, these procedures are limited in widespread use due to the limited availability at all centers.

• Also, the costs involved in the procedures may limit their use. Also, the fluoroscopy guided procedure has associated harmful effects of radiation involved in the procedure.

• Hence, a cheaper and readily available alternative to them can help in better management of SI joint dysfunction related back pain. Importance for research:

• There is no quality evidence in the literature comparing unguided SI joint infiltration with other standard techniques.

Material and Methods: Study duration: 6 months Sample size and statistical procedures used:

• The study design is a randomised control, double blinded trial with block randomization with variable block size. Schedule generated before hand using SPSS software.

• The sample size is calculated using n Master v 2 software with the following assuming a 5% level of significance (2 sided); 80 % power and -10% non inferiority margin.

• The required sample size obtained is 30 in each group on the basis of above assumptions. However, 34 patients in each arm (total 68), taking into account 10% dropout rates, will be the final sample size.

Results: Comparison between the two groups was on the following parameters- Pre procedure VAS (general and provocative), post procedure VAS (general and provocative), JOA, ODI. These analysis were compared on follow up at 1 week. 6 weeks, 12 weeks. No statistical difference was found in any of the parameters. The need was repeat injection was assessed on follow up. The probability of needing repeat injection on follow up was similar in the two groups. No difference between the two groups was found with respect to comorbidities. Conclusion: Ultrasound guided SI joint infiltration offers no added advantage over free hand guided injections.

Novel Technologies

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P471: Opioid Free Analgesia in Posterior Lumbar Fusion Surgery to Enhance Surgery

Aashish Ghodke ¹ , John John ¹ , Fouzia Kader ¹ , Birender Balain ¹ , Dr Jayesh Trivedi ¹ , Matthew Ockendon ¹ , Jan Kuiper ¹ , Sudarshan Munigangaiah ¹ , Sujay Dheerendra ¹ , and Rishi Trivedi ¹

¹ Robert Jones & Agnes Hunt Orthopaedic Hospital, Oswestry, United Kingdom

Introduction: Opioids have been a cornerstone of postoperative analgesia for many years; however, they are associated with many adverse effects that may prevent patient recovery after surgery. Surgeons and Anesthetists have opted many strategies to combat this epidemic, which typically incorporate a standardized, multimodal analgesic regimen with nonopioid agents, spinal anesthesia and regional blocks to control pain after Orthopedic surgery. On the contrary, Spine surgery has always suffered due to the lack of regional alternatives and hence pain management post-surgery. Enhanced recovery after surgery (ERAS) and multimodal analgesia (MMA) are established care models that minimize perioperative opioid consumption and promote positive outcomes after surgery. Opioid-free analgesia (OFA) is an emerging technique that may achieve similar goals. The purpose of this study was to evaluate an ORA (Opioid-Reduced Analgesia) regimen with enhanced recovery after open posterior lumbar fusion surgery. And compare perioperative opioid requirements with a matched cohort of patients managed with traditional Opioid-Containing Analgesia (OCA). Material and Methods: The authors performed a retrospective analysis of prospectively collected data from Jan 2015 to Dec 2016 at RJAH, Oswestry. In all, 66 patients were identified, of whom 26 did and 40 did not have spinal anesthesia. The ORA regimen patients had General Anesthesia with low dose spinal anesthesia prior to induction using 1-4 mls of .25% Bupivacaine, dose calculated as per the predicted duration of surgery. The OCA regimen patients had General Anesthesia without any spinal but with traditional intra-operative opioid analgesia. The primary outcome studied was total perioperative opioid consumption (total morphine equivalent and postoperative oxycodone). The secondary outcomes studied were postoperative pain scores (the mean worst VAS pain score in recovery and at postoperative day two) and the mean length of stay in the hospital. Results: In the spinal group, the mean total amount of perioperative morphine equivalent was 15 grams less, and postop 48 hr oxycodone 70 grams less, mean LOS was over one day less, and the mean VAS for pain in recovery 3 points lower. The Spinal group mobilised at a mean of 18 hrs vs 32 hrs for the GA group. All these results were statistically significant (P < .001).

Conclusion: For many patients with a long-term opioid misuse disorder, the first episode of opioid consumption can be traced to the perioperative period. Adding a spinal anesthetic to a GA reduces the perioperative opioid consumption and hence helps in lessening the burden of the opioid epidemic. Also, it helps in an enhanced recovery after surgery with a shorter length of stay and reduced pain scores.

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P472: One Year Experience in the Use of a New Expendable Cage and Large Endplates for Thoracolumbar Vertebral Body Replacement

Andreas N. Reinke ¹ , Bernard Magudya ¹ , Gordian Schmid ¹ , Bastian Stemmer ² , Michael Kraus ³ , Ehab Shiban ²

¹ Donau-Ries-Klinik Donauwörth, Spine Center and Neurosurgery, Donauwörth, Germany

² University Augsburg, Department of Neurosurgery, Augsburg, Germany, ³ Orthix, Augsburg, Germany

Introduction: Subsidence is the most common complication following thoracolumbar vertebral body (VB) replacement with expandable cages. Implants with large endplates are now being used in order to reduce the rate of subsidence. However, these require more elaborate preparations of the vertebral endplates which may lead to higher surgical morbidity. Herein we present the 30-Day morbidity following VB Replacement with these devices. Material and Methods: We retrospectively reviewed medical records of all patients who underwent a corpectomy and implantation of an expendable cage with large endplates (Posidon, Fa. Signus) between June 2018 and September 2019. We included cases with one level of trauma which were operated without additional platting and excluded infectious and tumorous cases. Demographics (age, sex, primary diagnosis), operative data (length of surgery, blood loss), surgical level, preoperative and postoperative neurologic status, perioperative complications, length of stay after surgery and measurement of footplate-to-vertebral body endplate ratio were analyzed. Results: The study included 20 consecutive patients who were treated with a vertebral body replacement in Th 11 n = 2, Th 12 n = 4, L1 n = 7, L2 n = 3 and L3 n = 4. Findings included a mean age of 60.6 years (32 to 72 years), mean surgical time of 140 min (90 to 190 min), mean blood loss of 560ml (250 ml to 900ml) and average length of stay of 13 days (5 to 34 days). All cases showed a footplate-to-vertebral body endplate ratio greater than .75. There were no surgical complications (e.g. neurological deterioration, vascular or lung injuries). Conclusion: Using of a large endplate for thoracolumbar vertebral body replacement in extendable cages is safe and not associated with a higher surgical morbidity. Nevertheless, long term results for clinical and radiographic follow up with focus on subsidence is desirable.

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P473: Subsidence Rate and Outcome After Thoracolumbar Vertebral Body Replacement With Large Endplates in Expendable Cages After One Year

Andreas N. Reinke ¹ , Bernard Magudya ¹ , Gordian Schmid ¹ , Bastian Stemmer ² , Michael Kraus ³ , and Ehab Shiban ²

¹ Donau-Ries-Klinik Donauwörth, Spine Center and Neurosurgery, Donauwörth, Germany, ² University Augsburg, Department of Neurosurgery, Augsburg, Germany, ³ Orthix, Augsburg, Germany

Background: Subsidence after thoracolumbar vertebral body replacement is very common. New implants with large endplates for vertebral body replacement are therefore been utilized. Aim of this study is to evaluate the subsidence rates of these implants. Method: We retrospectively reviewed medical records of all patients who underwent a corpectomy and implantation of an expendable cage with large endplates (Posidon, Fa. Signus) additional to a dorsal instrumentation between June 2018 and September 2019. Surgical and neurological outcomes were evaluated at a minimum follow-up of 12 months. Results: We included 20 consecutive patients who were treated by a vertebral body replacement in Th 11 n = 2, Th 12 n = 4, L1 n = 7, L2 n = 3 and L3 n = 4. Findings included a mean follow up period of 13 months (12 to 22 months), mean age was 60.6 years (32 to 72 years) and mean VAS improved form 8 preoperative to 2 during follow up. All cases showed a footplate-to-vertebral body endplate ratio greater than .75. There were no major complications. In two cases (10%) there was subsidence recognized two months after surgery and one case with asymptomatic screw loosening. All without the need for revision surgery. Conclusion: Using of large endplates for thoracolumbar vertebral body replacement in extendable cages is safe and is associated with low subsidence rates.

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P474: How to Confirm and Document Adequate Lumbar Spine Discectomy Intraoperatively?

Joseph Boktor ¹ , Miriam Kakaire ¹ , Ashish Khurana ¹

¹ Royal Gwent Hospital, Trauma and Orthopaedics, Newport, United Kingdom

Introduction: Posterior lumbar discectomy is a common procedure for acute disc prolapse, especially in patients with neurological deficit¹. The recurrence rate varies 5-18% ². This could be due to inadequate removal of disc material with residual disc or wrong level/side. On the other hand, it could be a true recurrence³. From 2002 to 2010, wrong level surgery and CES surgical failures constituted 9.9% each, of spinal surgery NHS Litigations with a cost of 12,000,000 GBP⁴. This study describes the authors’ technique to confirm and document adequate correct level discectomy. Material and Methods (Technique): Pre-incision fluoroscopy was undertaken to confirm the level and side (Figure 1). Further fluoroscopy was undertaken before breaching ligamentum flavum (Figure 2). Central decompression/micro-discectomy was performed according to surgeon’s preference and the size of the disc. Once discectomy was completed, probes are placed in the disc space and nerve foreman to fluoroscopically document the extent of decompression (Figure 3). The removed disc fragments were collected and kept aside. Following surgery, a photo of the disc material (with scale and patient’s label) was taken and included in the patient records (Figure 4). Results: The use of intraoperative fluoroscopy to confirm the correct level and side in lumbar discectomy is recommended by the British association of spine surgery (BASS). This technique is useful for the first point avoiding residual disc (wrong level) ³. Nevertheless, adequate discectomy cannot be confirmed apart from postoperative MRI. Hence, the use of photos showing the excised disc fragments’ volume could form a robust low cost documentation of adequate surgery. This could be undertaken in all discectomy surgeries without any extra cost or patient inconvenience. This provides substantial medicolegal evidence of adequate discectomy especially in CES surgery. Conclusions: Authors recommend using intraoperative photos of the excised disc material to be taken in all lumbar discectomy surgeries.

References

1. Peul WC, van Houwelingen HC, van den Hout WB, et al. [2007]. Surgery versus prolonged conservative treatment for sciatica. N Engl J Med.356: 2245-2256. DOI: 10.1056/NEJMoa064039.

2. Hlubek RJ, Mundis GM. [2017]. Treatment for Recurrent Lumbar Disc Herniation. Curr Rev Musculoskelet Med. 10(4): 517–520. DOI: 10.1007/s12178-017-9450-3.

3. Jon DL, Rachel AM, Anna NA,Tosteson TD, EJ, Jay AK, Richrd JH.[2013]. Magnetic Resonance Imaging Predictors of Surgical Outcome in Patients with Lumbar Intervertebral Disc Herniation. Spine (Phila Pa 1976).38(14): 1216-1225. doi: 10.1097/BRS.0b013e31828ce66d.

4. Cross CE, Kapoor V, Todd B, Bhutta MA. [2018].The Litigation Burden To The NHS From Spinal Injuries And Surgery: Analysis Of 236 Consecutive Closed Claims. Orthopaedic Proceedings. Vol. 94-B, No. SUPP_XXVI. https://online.boneandjoint.org.uk/doi/abs/10.1302/1358992X.94BSUPP_XXVI.BASS2011-031

5. Irace C, Corona C [2010]. How to Avoid Wrong-Level and Wrong-Side Errors in Lumbar Microdiscectomy. J Neurosurg Spine. 12(6):660-5. DOI: 10.3171/2009. 12.SPINE09627.

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P475: Novel Technique for Intraoperative Imaging of the Vertebral Artery in Patients Undergoing O-Arm Navigational Dorsal Osteosynthesis of the Cervical Spine: Case Series

Orlin Pavlov ¹ , Nikolay Mirchev ¹ , Alexa Ruiz ¹ , and Robert Behr ¹

¹ Klinikum Fulda, Department of Neurosurgery, Fulda, Germany

Introduction: The incidence of fractures in the upper cervical spine in elderly patients (>65 years) after trauma lies between 1,26% and 3%. The incidence of the vertebral artery injuries (VAI) after trauma is reported to be between 0, 5% and 88%. The vast majority of those remain clinically silent. There are three major methods to determine VAI: ultrasonography, computed tomography angiography (CTA) and magnetic resonance angiography (MRA). Methods and materials: This is a retrospective review of case series of three patients, who underwent an O-Arm navigated dorsal osteosynthesis because of traumatic cervical spine fracture. A novel technique for the intraoperative visualization of the vertebral artery using hybrid technique from two visualization modalities- O-Arm navigation and CTA was used for intraoperative imaging of the vertebral artery during screw placement. An intraoperative CTA/Navigation was carried out before and after the insertion of the screws. Results: None of the ten screws (massa lateralis or pedicle screws) showed impingement on the vertebral artery. None of the patients develop a new neurological deficit postoperatively. Conclusions: With this hybrid technique for direct intraoperatively imaging of the vertebral artery, it could be possible to bring the iatrogenic VAI to 0%, especially with patients who already experienced VAI due to the trauma. Further studies are required to confirm the results.

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P476: Treatment of Isolated Chronic Low Back Pain With Paddle Spinal Cord Stimulator

Christian Ivan Lucas Fras ¹ , Sebastian Fras ¹ , and Christian Fras ¹

¹ Institute for Spinal Surgery, Broomall, USA

Introduction: Spinal cord stimulators (SCS) have traditionally been used to treat extremity pain, particularly lower extremity pain, with or without a component of low back pain. However, the utility of SCSs in treating low back pain, particularly isolated chronic low back pain (CLBP), without any radicular component, has not been widely studied. For many patients with CLBP, surgical intervention has been focused on other remedies, including fusion or disc replacement. The goal of this study was to assess the efficacy of SCSs in treatment of isolated CLBP, without any extremity complaints. Materials and Methods: 20 consecutive patients were identified who had undergone permanent surgical implantation of a paddle lead SCS prior to January 15, 2018. All patients in this cohort had exclusively CLBP secondary to lumbar spondylosis, without any radicular leg pain; all patients had failed non-operative treatment (PT, medications, injections, etc), and had a successful trial SCS with a separate, independent pain management specialist, and had passed a psychological screening evaluation. VAS and ODI scores were recorded immediately pre-operatively, as well as at all post-operative visits. Minimum 2 year follow up was obtained for all patients. Results: All 20 patients were followed for a minimum of 2 years. Final follow up, including identification of VAS and ODI scores was obtained either in the office as part of office visit, or by telephone interview. Mean pre-operative VAS score was 8.1 (SD 1.57); mean VAS score at final (minimum 2 year) follow up was 3.1 (SD 3.1). Mean pre-operative ODI score was 64.1 (SD 11.7); mean post-operative ODI score at final (minimum 2 year) follow up was 30.1 (SD 20.3). Conclusion: Surgically implanted paddle SCSs can be used successfully to treat CLBP related to lumbar spondylosis. In this study, mean improvement of VAS and ODI scores was greater than 50%, comparable to results reported in the literature for other interventions, including lumbar fusion. SCS may be considered as a viable treatment option, for treatment of CLBP in patients who have failed multimodal, interdisciplinary non-operative treatment.

332

P477: Five Year Survivorship of Paddle Spinal Cord Stimulators

Christian Ivan Lucas Fras ¹ , Sebastian Fras ¹ , and Christian Fras ¹

¹ Institute for Spinal Surgery, Broomall, USA

Introduction: Paddle spinal cord stimulators (SCS) are increasingly used to treat chronic back and extremity pain. The longevity of these devices has not been extensively studied. It remains unclear how often these implants are removed, or how long patients keep these devices. This study investigates how frequently these devices are removed within a minimum 5 year follow up. Methods: 45 consecutive patients were identified who had undergone paddle SCS placement at least 5 years prior to the most recent follow up; if the patient had not had follow up at least 5 years after SCS implantation, a telephone conference was had with the patient, with all 45 patients querried as to whether they retained their paddle SCS. Results: Of the 45 consecutive patients identified, mean follow up was 86 months (SD ± 15 months). Minimum follow up was 60 months. Of these 45 patients, 34 retained their paddle SCS implant. 7 had their original operating surgeon (the senior author) remove their implant; 4 patients had their implant removed by another surgeon. All patients reported the reason for explantation to be related to lack of continued benefit of the SCS. Conclusion: Paddle SCS medium term survivorship was 75.6%. This was less than anticipated, but must be placed in the context of an intervention with low morbidity when compared to other surgical interventions for chronic back and leg pain. The study demonstrates the need for a comprehensive, interdisciplinary approach to identify patients for whom paddle SCS may prove to be a durably successful treatment.

345

P478: Prospective, Consecutive Series of Novel Poly-Ether-Ketone-Ketone Interbody Cages Compared to Titanium Interbody Cages in Patients Undergoing ACDF Procedures

Fedan Avrumova ¹ , Nicole Utah ¹ , Christina Dowe ¹ , Daniel Alicea ¹ , Celeste Abjornson ¹ , Frank Cammisa ¹ , Darren Lebl ¹

¹ Hospital for Special Surgery, Spine Surgery, 10021, USA

Introduction: Titanium implants have been of growing interest in anterior cervical discectomy and fusion (ACDF) procedures. Traditionally, titanium implants reported higher rates of subsidence due to higher elastic modulus than bone potentially causing stress shielding. Polymers such as PEEK, poly-ether-ether-ketone, have been primarily utilized to mitigate the modulus mismatch but is hydrophobic and elicits the formation of a biofilm layer thereby not allowing bone apposition. A novel material, PEKK, poly-ether-ketone-ketone, can be 3D printed for highly designed surfaces, elastic modulus similar to bone, and is hydrophilic allowing for bony on-growth. PEKK aims to merge the advantages of materials such as titanium and PEEK, participating in a solid fusion. The purpose of the study is to evaluate the clinical outcomes of a PEKK cage in ACDF procedures compared to a previously used titanium cage. Methods and Materials: This study compares a prospective, consecutive series of patients receiving a PEKK interbody implant to a retrospective matched series of patients receiving a titanium interbody spacer. The retrospective arm of the study included 50 patients undergoing 1-3 level ACDF’s, utilizing a titanium cage from 2014-2019. The prospective analysis included 50 patients, undergoing the same ACDF’s utilizing a PEKK cage from 2019 and onward. Both cohorts’ procedures also included bone grafting and anterior plating. All procedures were performed at same institution by one of two surgeons. The primary outcomes are rates of fusion and subsidence. Fusion was defined as bridging bone with less than 3° of flexion-extension motion. Subsidence was defined as a decrease in disc height of > 3 mm at the 6-month post-operative from discharge and measured from Computed Tomography (CT) radiographic images. Additional outcomes assessed included pain levels pre- and post-operatively, secondary surgical intervention, and postoperative opioid usage. Results: The average age was 57.7 ± 10 years in the titanium group and 56.6 ± 11 years in the PEKK group. Among patients who have received PEKK cages, there was an average 28.1% decrease in Visual Analog Scale (VAS) neck scores and a 31.7% average decrease in VAS arm scores at the 6-month post-operative mark from baseline and a 10.5% decrease in Neck Disability Index (NDI) scores. In the PEKK group, 1-, 2-, and 3-level cases were distributed in 36%, 42%, and 21% of patients, respectively. In the titanium group, 1- 2-, and 3- level cases were distributed in 26%, 42%, and 32% of patients, respectively. Subsidence was more prevalent in the titanium group than the PEKK group. Fusion rates were greater than 90% in both groups and similar at 6 months. No differences were found in secondary interventions or opioid usage. Conclusion: Our results indicate PEKK cages as a viable alternative to titanium implants in ACDF procedures, especially regarding pain intensity and frequency reduction at the latest follow-up. With a more similar elastic modulus to bone, PEKK cages exhibited less subsidence than titanium cages.

425

P479: A Multicenter Comparison Between the Mazor X and the Renaissance in Robot-Assisted Spine Surgery: A Propensity-Matched Analysis of 2671 Screws and 400 Patients With a 1 Year Minimum Follow-Up

Nathan Lee ¹ , Ian Buchanan ¹ , Venkat Boddapati ¹ , Justin Mathew ¹ , Paul Park ¹ , Eric Leung ¹ , Avery Buchholz ² , John Pollina ³ , Ehsan Jazini ⁴ , Colin Haines ⁴ , Thomas Schuler ⁴ , Christopher Gooed ⁴ , Joseph Lombardi ¹ , Ronald A. Lehman ¹

¹ The Och Spine Hospital at New York-Presbyterian, New York, USA

² University of Virginia Health System, Charlottesville, USA

³ State University of New York, Buffalo, Buffalo, USA

⁴ Virginia Spine Institute, Reston, USA

Introduction: As new robot technology continues to be introduced into practice, it is important for the surgeon to know how these new advances are influencing screw accuracy and outcomes. This is the first multicenter study comparing robot systems. Material and Methods: In this multicenter study, we included adult (≥18 years old) patients who underwent robot-assisted spine surgery with either the Renaissance or Mazor X system. A propensity score matching algorithm based on perioperative factors (e.g. demographics, comorbidities, primary diagnosis, prior spine surgery, pelvic fixation, instrumented levels, planned robot screws) was employed to control for the potential selection bias between the two robotic systems. Primary outcomes included operative efficacy (robot time per screw), robot complications, and clinical outcomes with a minimum 1 year follow up. Results: A total of 400 adult patients were included in this study (200 Renaissance, 200 X). The most common preoperative diagnoses included high grade spondylolisthesis (47.5%), degenerative scoliosis (20.3%), and degenerative disc disease (15.8%). The mean number of instrumented levels was 4.0. The mean number of planned robot screws was 7.4. The Mazor X achieved a significantly shorter robot time per screw (X: 5.8 minutes vs Renaissance: 7.2 minutes, P = .016). The screw accuracy for both robots were excellent (X: 99.0% vs Renaissance: 98.1%, P =.078). However, the robot abandonment rate due to registration issues was significantly higher for the Renaissance (4.5%) than the X (.5%, P =.010). Other intraoperative complications such as dura tear, motor/sensory deficits, blood transfusion, and return to the OR during same admission was similar between robots (P > .05). Interestingly the LOS was nearly a day shorter for the X (4.7 days) than the Renaissance (5.5 days, P < .001). The 90 day and 1 year complication rates were low and similar between robot cohorts. Conclusion: Our multicenter study demonstrates that the Mazor X achieves greater operative efficacy (lower time spent per screw), higher reliability (lower robot abandonment), and potentially lower overall costs given the nearly 1-day reduction in hospital length of stay. These findings are likely the result of the recent advancements in Mazor X technology, particularly the cutting edge pre-operative planning software.

493

P480: Safe C2 Eosinophilic Granuloma Removal Using a Curved Bone Removal Device

Michael Millgram ¹ , Richard Guyer ² , Ran Harel ³ , Scott Kutz ⁴ , and Ely Ashkenazi ¹

¹ Assuta Medical Centers, Israel Spine Center, Tel Aviv, Israel

² Texas Back Institute, Plano, USA

³ Sheba Medical Center, Spine Surgery Division, Ramat Gan, Israel

⁴ Minimally Invasive Neurosurgery of Texas, Plano, USA

Introduction: Surgical treatments to the upper cervical levels are potentially more complicated compared with other spinal surgeries. The location of these vertebrae and their proximity to vital blood vessels, nerves and the esophagus, hold the risk of significant complications. However, some medical conditions necessitate surgical treatment to these spinal regions. The dimensions and shape of surgical tools, such as the straight high-speed drill, dictate the required access route to the treated region. In order to avoid unsafe approaches and to facilitate a safer access route to the tumor, the surgeon may choose to drill through healthy tissues. However, the removal of supporting bone structures may lead to spinal instability and require spinal fusion, thus complicating patient recovery. A recently developed device offers a potential solution to this problem. A curved-tip drilling device allows the surgeon to reach difficult-access areas with minimal bone-removal. The use of this device is demonstrated here in a recent tumor resection procedure. Material and Methods: A 62-year-old male with a vertebral tumor at the C2 vertebra was operated for an anterior cervical discectomy and fusion (ACDF) procedure on the C5-C6 vertebrae through a posterior approach. The patient was without prior spine surgeries and other co-morbidities. The tumor's location at the anterior part of the vertebra and its proximity to neural structures complicated its surgical removal using traditional tools and methods and required extensive removal of healthy tissue. However, during the ACDF procedure the surgeon noticed an opportunity to safely remove the tumor using the new device with minimal damage to healthy tissues. Results: The procedure was uneventful and without complications. The entire tumor removal using the device required two minutes. The total operation length was 63 minutes and the estimated blood loss was 200 ml. Histopathological examination revealed characteristic eosinophilic granuloma. The patient was hospitalized for five days and then released without further complaints. Conclusion: A safe, quick efficient removal of a vertebral tumor without removal of healthy surrounding tissues was facilitated using the new device, sparing the patient from potential spinal instability. This case presentation demonstrates the ability to safely access difficult areas using the new device.

543

P481: Self-Adaptable Health Record Database for Patient-Reported Outcomes and Clinical Research

Leonardo Pellizzoni ¹ , Frederico Arriaga Criscuoli de Farias ² , Sabrina Busnello ² , and Asdrubal Falavigna ¹

¹ University of Caxias do Sul (UCS), Health Sciences Postgraduate Program, Caxias do Sul, Brazil

² University of Caxias do Sul (UCS), Cell Therapy Laboratory and Clinical Studies and Basic Models of Spinal Disorders Laboratory, Caxias do Sul, Brazil

Introduction: A dataset with patient information allows a comparison between different clinical treatments in many fields of medicine as well as the efficient use of medical resources. Patient-reported outcome measures (PROMs) collect data directly from patients to be used in clinical practice by helping decision making and tailoring treatments according to the patient’s needs. The authors present a novel database to overcome barriers related to the data collection, automatically calculating the questionnaire results displayed in graphics on the patients’ dashboard and focus on the active follow-up of the participants. Material and Methods: The development of the database used the Iconix methodology for modeling the process and the specification of technological requirements. The features of the developed database consist in creating questionnaires for later use in the data collection design of the clinical studies with multiple research centers. The clinical study follows the design and the schedule of patient data collection proposed by the researchers. Both the proposed database and the questionnaires used for data collection were presented in three languages that were used according to the users’ need: Brazilian Portuguese, Spanish, and English. Regarding the questionnaires, different types were tested with the strategy focusing on building PROMs with a variable quantity of questions and possible answers. The answer to the questionnaire could be single choice, multiple choice, numerical, date and text. The system was designed to prevent advancing to the next question if the answer to that question was not given. The Oswestry disability index (ODI) and the Euro quality of life 5D (EQ5D) questionnaire were recorded and used in the developed database. Additional information was collected with questions regarding procedure costs, clinical information, surgical and patient’s outcome data. The Post-Study System Usability Questionnaire (PSSUQ) was applied to validate the usability and usefulness of the proposed database. The PSSUQ uses 19 questions divided into four different sub-scores. All the 19 questions use a Likert scale from 1 (strongly disagree) to 7 (strongly agree). Higher scores indicate better ratings in all the scores. Results: The database enables researchers to use the questionnaires defining the time of the data collection according to the needs of each clinical study. The system facilitates the patient answers without any personal interference from smartphones, tablets or computers. The questionnaire’ scores were calculated automatically in real time and displayed in graphics on the patients’ dashboard. The evaluation of the usability and usefulness of the developed database used 8 people divided into two equal groups (physicians and medical students). Conclusion: The proposed electronic health record database allows a friendly and flexible use of PROMs according to the population, needs in practice and clinical settings. The platform promotes active and direct data collection from patients and physicians in English, Portuguese and Spanish. The questionnaires used in the study were created and maintained by physicians.

553

P482: Improving the Efficiency of Disc Space Preparation in Transforaminal Lumbar Interbody Fusion: Clinical Experience and Meta-Analysis

John Peloza ¹ , Hani Malone ² , Larry Khoo ³ , Michael Millgram ⁴ , and Ely Ashkenazi ⁴

¹ Center For Spine Care, Dallas, TX, USA

² Scripps Clinic Torrey Pines, La Jolla, CA, USA

³ The Spine Clinic of Los Angeles, Los Angeles, CA, USA

⁴ Assuta Medical Centers, Israel Spine Center, Tel Aviv, Israel

Introduction: Effective endplate preparation is vital to the success of transforaminal lumbar interbody fusion (TLIF), as the risk of pseudarthrosis can increase following inadequate preparation. However, extensive preparation efforts increase procedure duration and may potentially irritate the nerve root or dura due to repetitive instrument passes. Therefore, several powered and manual devices have been developed to improve the efficiency of this stage while reducing the number of instrument insertions. This study reports on the authors’ in vitro and in vivo experience with one such powered device designed for intervertebral endplate preparation. A systematic literature review and meta-analysis of relevant studies has been conducted and compared with the authors’ experience. Material and Methods: Follow-up records of 143 patients who underwent TLIF procedures using the device were used to calculate the baseline pseudarthrosis rate. An in vitro cadaver study was conducted by two experienced surgeons on five levels of a freshly thawed specimen. The number of instrument passes was recorded for each level. After the conclusion of the procedures, the cadaver disc spaces were sectioned and the endplates were observed for any perforations and the extent of the prepared area was calculated. For the comparative analysis, the literature was systematically surveyed for studies describing TLIF cadaver studies. The extent of the prepared area and number of instrument passes were extracted for the meta-analysis. Results: 1.4% of the patients required reoperation to treat pseudarthrosis, lower than reported literature rates. An average difference of 18.5 instrument insertions was found between the powered and the traditional preparation methods in the cadaver study. The prepared endplate area increased by 83% using the dedicated device, and endplate perforation was reduced by 33%, compared with traditional tools. 252 papers were identified in the systematic literature review. Ten of these articles described a TLIF disc preparation cadaver study. These articles included 14 experimental arms describing traditional approaches (open and minimally invasive) and 7 experimental arms with innovative dedicated devices for disc space and endplate preparation. The pooled percentages of prepared endplate area were 49.5%, 56% and 42.7%, for the open, minimally-invasive and dedicated devices groups, respectively, and required 43, 31 and 7.6 instrument insertions, respectively. The use of the dedicated devices increased the relative prepared endplate area by an average of 23% (range: 3-47%). Conclusion: As the meta-analysis reveals, disc space preparation using dedicated innovative devices can substantially reduce the number of required instrument insertions. The use of innovative dedicated devices, including the device used by the authors, resulted in relative improvement in the prepared endplate area. This finding can be translated to a reduction of complication rates in a hospital setting. As a result, these devices have the potential to improve the clinical outcome and reduce reoperation rates and subsequent costs. Further study to elucidate the potential advantages of dedicated endplate preparation instruments would be beneficial.

555

P483: Modified Transforaminal Thoracic Interbody Fusion (TTIF): Technique Description and Case Series

Michael Millgram ¹ , William Beutler ² , Richard Guyer ³ , and Ely Ashkenazi ¹

¹ Assuta Medical Center, Israel Spine Center, Tel Aviv, Israel

² Pennsylvania Spine Institute, Harrisburg, PA, USA

³ Texas Back Institute, Plano, TX, USA

Introduction: The incidence of asymptomatic thoracic disc herniation (TDH) may be as high as 37%, as shown in an MRI study on asymptomatic individuals. The improvement in diagnostic imaging abilities has led to more frequent and early-stage diagnosis of thoracic disc herniation. Removal of the disc is required when neurological deterioration occurs secondary to spinal cord compression. The approach to thoracic disc excision remains controversial. The posterior approach, though familiar to most spine surgeons, lost favor due to a high rate of neurological deterioration. The anterior approach has consequently gained popularity but entails a larger magnitude of surgery if open and is technically demanding if approached thoracoscopically. Approaching the thoracic disc posteriorly following unilateral facetectomy and pediculectomy was first described in 1978. The use of this relatively easier approach would be desirable while increasing the safety and reducing the length of the procedure. Transforaminal thoracic interbody fusion (TTIF) was first reported in 2010 as a potential approach to treat TDH. The approach is limited by the narrower distance between the bilateral pedicles, especially at the upper thoracic spine levels. Therefore, it is more difficult to achieve safe decompression at the upper thoracic spine with TTIF. This study presents a technique for posterior unilateral thoracic discectomy through a hemilaminectomy, unilateral facetectomy, and hemipediculectomy, facilitated by a novel curved dorsally-shielded high-speed device. Introducing the device ventral to the dural sac allows removal of calcified and soft disc fragments without relying on forceful manual maneuvers and avoiding manipulation of the spinal cord. Material and Methods: The maximal disc protrusion side is approached through a hemilaminectomy, unilateral facetectomy, and hemipediculectomy removing the superior half of the pedicle and exposing the disc transforaminally, allowing its removal using the device. Pedicle fixation and fusion concluded all procedures. Between June 2014 and November 2018, 12 patients (6 males and 6 females, ages 23-74) underwent posterior thoracic discectomy applying the above approach. The affected levels were D3-4(1), D5-6(1), D7-8(1), D9-10(1), D10-D11(3), D11-12(4) and D12-L1(1). Results: All patients presented with neurological deterioration and all but two with pyramidal signs. All procedures were uneventful and without dural tears. None of the patients deteriorated neurologically. Average back pain VAS scores decreased by 1.2. Average leg pain VAS scored decreased by 2.2. Conclusion: The new curved device and approach allows for a faster safer thoracic disc herniation removal.

611

P484: Spine Surgery Assisted by Augmented Reality and Virtual Reality: A Systematic Review

Yanting Liu ¹ , Min-Gi Lee ¹ , Yadhu Lokanath ² , and Jin-Sung Luke Kim ¹

¹ Seoul St. Mary’s Hospital, College of Medicine, The Catholic University of Korea, Seoul, South Korea, Department of Neurosurgery, Seoul, South Korea

² Aster CMI Hospital, Department of Neurosurgery, Bengaluru, Karnataka, India

Introduction: It has been more than 100 years since Cushing released the first case presentation of x-ray image detection. With the development of science and technology, computer-aided surgery has become an integral part of modern surgery practices. In addition to x-ray technology, a series of advanced surgical assisted devices have also emerged. Navigation technology integrating surgical microscopy with head-up reality was first introduced in the 1980s and involved the superposition of virtual images on the optical field. The use of this technology gradually increased and has been used widely in various craniocerebral operations in the last decades. As spine surgical treatments have become more precise and non-invasive, virtual reality (VR) and augmented reality (AR) techniques for spinal surgery have gained interest because of their potential advantages in combination with modern surgical treatments. Although few clinical applications of AR and VR techniques have been published, the pioneering use of these techniques in spinal surgery shows great potential in improving surgical accuracy or reducing intraoperative human radiation exposure. Research in the use of these applications warrants further research. Thus, this review will summarize the current research assessing how AR and VR methods can be utilized in different spinal fields. Material and Methods: Our systematic review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines to ensure accurate representation of data. The following databases were searched from the earliest record until June 15, 2020: PubMed, Web of Science, Cochrane Library, and Embase. Because of data and method heterogeneity, statistical analyses could not be used to conduct a meta-analysis. Results: A total of 387 articles were identified using our database search and manual search. After screening each paper title and abstract for relevance, 71 articles were eligible to continue screening. Finally, 47 articles were included after full-text screening: AR (n = 36); VR (n = 11); Pedicle screw placement (n = 27); and Others (n = 20). The popular AR related systems and equipment are used: head-mounted displays (HMD), HoloLens glasses, and augmented reality surgical navigation (ARSN) systems. VR: Virtual surgical training system, immersive touch. The most used surgical methods are pedicle screw placement, injection and biopsy, vertebroplasty and ex/indural mass resection. Among them, the ARSN system also could cooperate with the robot robot system to reach a high clinically acceptable in Pedicle screw placement. The system with the most problems is Microsoft HoloLens with tedious registration procedures, insufficient brightness and lack of depth perception. Conclusion: Currently, the overall number of surgical cases using VR and AR techniques in research studies are limited, and operative and postoperative statistical data are lacking because of the technology’s high price and uncertain clinical efficacy. Further, technical problems require proper attention, and the lack of compatibility between new and existing technology must be addressed. With medical laws changing and surgical automation becoming more advanced, its utility may far exceed its cost. Innovations in VR and AR techniques will herald a new era of spinal surgery and care in the near future.

639

P485: Piezosurgery Application for Symptomatic Thoracic Spinal Stenosis Caused by Ossification of Ligamentum Flavum or Ossification of Posterior Longitudinal Ligament or Thoracic Disc Herniation: A Systematic Review and Meta-Analysis

Baoliang Zhang ¹ , Zhongqiang Chen ¹ , Guanghui Chen ¹ , Xiaoxi Yang ¹ , and Tianqi Fan ¹

¹ Peking University Third Hospital, Beijing, China

Introduction: With the development of ultrasonic device, piezosurgery has been applied in the treatment of thoracic spinal stenosis (TSS) in clinical practice. However, due to the low prevalence of TSS, the efficacy and safety of piezosurgery remain uncertain. Therefore, this study evaluated the effect and complications of ultrasonic curette and traditional drill-assisted laminectomy for treating TSS through a meta-analysis, providing more reliable clinical evidence. Material and Methods: Pubmed, Embase, Web of Science, Cochrane Library, CNKI and Wanfang database were searched for all relevant clinical controlled studies from inception to August 2020. Two investigators independently performed literature screening, quality evaluation and data extraction according to the inclusion and exclusion criteria. Meta-analysis was performed to compare the safety and effectiveness of two techniques by Stata 14 software. Fixed effect model or random effect model was selected according to heterogeneity. Results: Five non-randomized controlled studies with a total of 235 TSS patients (104 in piezosurgery group and 131 in drill group) were included. Pooled results showed no significant difference in preoperative JOA score [SMD = -.08, 95% CI (-.34, .19), P = .567], postoperative JOA score [SMD = .14, 95% CI (-.17, .45), P = .387], JOA score at last follow-up [SMD = .13, 95% CI (-.14, .39), P = .344], excellent and good rate of JOA [OR = 1.06, 95% CI (.64, 1.75), P = .197] between two groups; Besides, no difference in the rate of dura or nerve injuries [OR = .65, 95% CI (.34, 1.25), P = .567] and overall complications [OR = .63, 95% CI (.34, 1.18), P = .148]. However, compared with the drill group, the piezosurgery group provided lower operative time [SMD = -1.42, 95% CI (-1.79, -1.05), P = .0001] and less blood loss [SMD = -1.59, 95% CI (-1.89, -1.29), P = .0001] during laminectomy, which was statistically significant. Conclusion: Piezosurgery-assisted laminectomy is a safe and effective surgical option for treating TSS. Compared with the drill, it can also significantly shorten the operation time and reduce the intraoperative blood loss. Large-sample, multicenter, high-quality randomized controlled trails need to further verify the consistency of this results.

795

P486: Design of a Novel Cephalic Traction System for the Treatment of Early-Onset Severe Scoliosis

Fernando Alvarado Gómez ¹ , Carlos Montero ¹ , Wilmer Godoy ¹ , Alexander Tristancho ¹ , María Alejandra Asmar ² , and María José Bravo Otero ³

¹ Instituto Roosevelt, Bogota, Colombia

² Universidad de los Andes, Bogota, Colombia

³ Universidad de la Sabana, Bogota, Colombia

Introduction: Severe early-onset scoliosis is known for the complications on pulmonary insufficiency, neurologic compromise and major difficulty on its management due to curve severity, in most cases, cobb angle greater than 100º. Treatment of this condition is challenging, as to why many authors have advocated the use of halo-gravity traction to allow gradual curve correction prior to surgery, not only to reduce the burden and perioperative complications but also to monitor neurologic function in the awake patient as traction force is increased, reducing the risk of permanent neurological damage. Even though cephalic-traction provides adequate corrective forces for severe deformities, it requires extended periods of bed rest and detriment of patients’ life quality. Given these conditions, we evaluated the need to create a novel, easy-to-use cephalic traction system that would allow the patients to receive the adequate halo-traction therapy without majorly decreasing their life quality and preventing their prostration. Materials and Methods: The traditional halo-traction system consists of attaching a ring to the patient's skull using screws and weights that, due to gravity, eject a force in the opposite direction. It has the problem that it is not easily adjustable to patient’s allocation, daily activities and the required force to support his body weight. It also has problems related with force. Although there is an effective method available using counter weight, our goal was to evaluate how viable it is to change the way this force is being applied in order to improve the treatment outcomes and its impact in patient's overall health. Results: A tripoidal metallic structure was developed consisting on a mechanically- driven pulley system that can also be used manually, with a set of buttons that allows health professionals to gradually increase the traction weight according to patient’s spinal curve condition. It is easily adaptable to all in-patient scenarios such as the beds, therapy-bicycles and restroom lavatories, and it may be adjustable to every out-patient scenario as well. It is powered by a rechargeable batteries system that ensures the application of the traction 24 hours a day. Conclusion: a novel cephalic traction system was designed and manufactured with a combination of a motor and manual system, giving the possibility of being easily operated either manually or automatically by all health professionals, reducing mistakes on weight upgrade and decreasing overall health complications. Further tests are needed in healthy volunteers to proof its safety so it may be implemented on patients with early-onset severe scoliosis requiring halo-traction therapy prior to surgical

850

P487: Arthroscope Assisted Transpedicular Approach for Spinal Cord Decompression

Ghanshyam Kakadiya ¹ , Viraj Gandbhir ¹ , and Kshitij Chaudhary ^1,2

¹ Topiwala National Medical College & BYL Nair Hospital, Department of Orthopaedics, Mumbai, India

² Sir H. N. Reliance Foundation Hospital and Research Centre, Department of Spine Surgery, Mumbai, India

Introduction: Posterior transpedicular decompression has become a standard surgery to achieve anterior spinal cord decompression. However, one of its main disadvantages is the inadequate visualization of the anterior surface of the dura. As most pathologies cause anterior spinal cord compression, frequently the surgeon has to rely on palpation to judge the adequacy of spinal cord decompression. We describe a technique that utilizes an arthroscope to visualize the anterior surface of the dura during transpedicular decompression. Material and Methods: 20 consecutive patients were operated on for neurological deficit using an arthroscope assisted unilateral transpedicular approach by a single surgeon. The pathologies treated with tuberculosis (12), fractures (6), metastasis (2). We retrospectively reviewed the preoperative, intraoperative and postoperative records. A 70-degree arthroscope was used in 11 patients and 30-degree was used in nine. Results: We found that both 30° and 70° arthroscopes provide a good visualization of the anterior surface of the dura during decompression without manipulating the spinal cord. Adherent epidural cuff in patients with tuberculosis could be peeled off the dura under direct visualization. A complete decompression on the far lateral side could be visually confirmed in spite of using only a unilateral transpedicular approach. The visualization was poor in two patients operated for metastasis due to repeated pooling of blood in the anterior cavity. Mean operative time was 4.5 hours with a mean blood loss of 477 ml. All patients with tuberculosis achieved complete neurological recovery. No patient had neurological deterioration. No iatrogenic dural tears were noted. Conclusion: Arthroscope assisted transpedicular decompressions can Improve the surgeon's operative field and magnification thereby ensuring complete decompression without Injuring the dura or spinal cord. As most modern theatres will have an arthroscope, it is a useful trick in the armamentarium of an orthopaedic surgeon.

925

P488: A Novel Device to Enhance Bone-to-Bone Interface in Spinal Surgery

Bronek Boszczyk ¹ , Masood Shafafy ² , Khalid Salem ² , and Karen McRae ³

¹ Trent University, School of Science and Technology, Nottingham, United Kingdom

² Queens Medical Centre, Spinal, Nottingham, United Kingdom

³ Clinical Research, Apt, France

Introduction: Optimal fixation between screw and bone is essential to achieve successful outcomes in spinal surgery. Currently, enhanced fixation is sought by augmenting a procedure with larger diameter screws and/or bone cement such as polymethylmethacrylate or calcium-based cements. A new unique braided Polyethylene Terephthalate (PET) sleeve was used to act as a plug in bone prior to the insertion of the pedicle screw, to enhance the quality of screw-to-bone interface particularly in worst case fixation scenarios such as revisions for screw loosening. With biomechanical studies having proven very favorable, the study aim was to investigate the safety profile for the use of such an implant in spinal surgery. Material and Methods: Following Ethical Committee approval, patients aged 21 to 75 years, undergoing a short-segment lumbar posterior instrumentation for degenerative lumbar spine pathology were approached for participation in a trial conducted at one institution. After completing a structured consenting process, data on age, gender, body mass index (BMI) and co-morbidities was collected. Additional data on visual analogue score (out of 100) (VAS), Oswestry Disability Index (ODI), EQ-5D%, adverse events, X-ray imaging for evidence of radiological loosening, C-reactive protein, and clinical status was collected at baseline, discharge, 6 weeks, 6 months, and 12 months. After approval for CE registration, the patients were followed for an additional 12 months to collect data on pain scores and identify any potential adverse events. Continuous data below is presented as a mean with the standard deviation (SD) shown in parentheses. Results: Over the period of 7 months commencing September 2017, sixteen patients were recruited (4 Males/12 Females) with a mean age of 55.6 (13.7) years and BMI of 29.1 (5.4). Data on patients who completed their 24-month review is presented. Mean scores pre-surgery and at 24-month follow-ups were as follows: for VAS 68.1 (19.6) vs 41.8 (22.9), ODI 51.1 (15.4) vs 36.1 (17.8), EQ-5D% 47.1 (19.2) vs 63.6 (20.7). There was no evidence of radiological loosening in any cases reviewed at 12 months, no recorded complication or clinical evidence of local or systemic sensitivity, and no adverse events relating to the implant. CRP readings were 6.2 (3) pre-surgery, 100.4 (80) at discharge, and 7.2 (5) at 12 months. Conclusion: The findings after 2 years support this implant system to be a safe augmentation to enhance the bone-to-screw interface in spinal surgery. The design of the implant and technique of insertion will be discussed.

1041

P489: Clinical Gait Analysis and Mapping of the Bony Fusion Following Sacrectomy: A Case Report

Jennifer Fayad ¹ , Máté Turbucz ^2,3,4 , Peter E. Eltes ^2,3,4 , Laszlo Kiss ^2,3,4 , Peter Pal Varga ² , and Aron Lazary ²

¹ Universita di Bologna, Department of Industrial Engineering, Bologna, Italy

² National Center for Spinal Disorders, Buda Health Center, Budapest, Hungary

³ In Silico Biomechanics Laboratory, National Center for Spinal Disorders, Buda Health Center, Budapest, Hungary

⁴ School of PhD Studies, Semmelweis University, Budapest, Hungary

Introduction: Total en-bloc Sacrectomy with wide oncological margins impacts the load bearing ability of the spinopelvic complex and the mobility of patients after surgery. The closed-loop technique (CLT) uses a single U-shaped rod to restore the lumbo-pelvic junction. This technique uses a non-rigid construct to avoid the stress shielding phenomenon and to promote bony fusion between the lumbar vertebrae and the pelvis. So far, the relationship of any spinopelvic reconstruction method and the fusion process has not been studied. In this study, a computational method was established to map the bony fusion at the level of the construct in addition to assessing the mobility of the patient based on the 6 years follow up (FU) clinical data. Material and Methods: Post-operative CT scans were collected from a male patient who underwent total sacretomy at the age of 42 due to chordoma. CLT technique was used to reconstruct the spinopelvic junction. The 3D geometry of the implant construct was defined. In order to investigate the bony fusion, a single axial slice-based voxel finite element (FE) mesh was defined. The Gray scale values were determined and using linear empirical equation the bone mineral density (BMD) values for each mesh element was assigned using a ten-colour coded category (1st category = 0 g/cm³, 10th category = 1.12 g/cm³). To demonstrate the cyclical loading of the construct at 6-year FU, the patient underwent a gait analysis session. The patient completed five walking trials mounting the Vicon plug-in-gait marker setup. Marker trajectories were acquired using a 6-camera motion analysis system (VICON MXT40, UK), and ground reaction forces using a force platform (AMTI OR6, USA) to calculate the joint kinematics and kinetics. Mean and standard deviation of data per gait cycle were then calculated over the 5 available repetitions per side and compared to normative data. Results: The developed method was able to map the bone remodelling at the fusion site. The volume distribution over time in the different BMD categories were determined and visualized. The highest BMD value volume on the first post-op CT was .04 cm³, .98 cm³ at the 2-year FU and 2.30 cm³ at the 6 years FU. The resulting gait was slow and slightly asymmetric with increased support on the left leg and a reduced propulsion power at the hip and ankle. Joint mobility was close to normal at all the joints, distally in particular. Conclusion: CLT provided strong lumbopelvic bony fusion within 2 years. Independent gait function was maintained, and load bearing abilities restored. The study results and the measurement method can be used for validation of complex patient specific FE models which can be useful for individualized preoperative surgical planning. Due to its relative simplicity, it is suggested to apply the developed measurement method for the scientific and clinical analysis of other surgical procedures for the reconstruction of the lumbo-pelvic junction after sacrectomy.

1061

P490: A Novel Anterior X-Shape Vertebroplasty for Cervical Spinal Stenosis: An Alternative Technique for ACCF

Yang Liu ¹ and Hao Liu ¹

¹ West China Hospital, Sichuan University, Department of Orthopaedic Surgery, Chengdu, China

Introduction: Recently, with the popularization of smart phone and change in the way of work and study, cervical spondylopathy (CS) has become more prevalent than the past decade, especially in young people. Surgical intervention including anterior approach cervical surgery (APCS), posterior approach cervical surgery and anterior-posterior approach cervical surgery is utilized to thoroughly remove the compression of nerve root or spinal cord and reconstruct the cervical spinal stability in patients with severe neurological symptoms. Thereinto, anterior cervical corpectomy and fusion (ACCF) is mainly applied to patients with localized spinal stenosis, segmental ossification of the posterior longitudinal ligament (OPLL) or enlarged osteophyte of posterior vertebra as it has sufficient range of decompression and extensive surgical vision. However, during perioperative period in classical ACCF, there are some drawbacks such as big trauma, subsidence of titanium mesh cage, bad fusion rates, breakage of plate and screw, and pain, bleeding and infection from autogenous bone donor site. Moreover, in the case of patients with non-obvious posterior osteophyte, spinal cord compression only located in the middle of the vertebral body or non-broad base OPLL, if the classic anterior cervical discectomy and fusion is adopted at this time, the range of decompression cannot meet the clinical requirements. Similarly, employing the ACCF seems to make a big fuss. Therefore, it is necessary to a new, safe and effective operation that can combine the two characteristics for this condition. Material and Methods: A novel anterior cervical X-sharp vertebroplasty (ACXVP) was performed to address cervical spinal stenosis. Firstly, V-shaped osteotomy (axial view) was performed on the anterior 2/3 vertebral body, and inverted V-shaped enlarged decompression (axial view) was performed on the posterior 1/3 vertebral body. Then, the free V-shaped bone was then trimmed and replanted in the affected vertebra as a supporting bone instead of the traditional titanium mesh. Finally, Zero-P cages were placed in each of the upper and lower vertebral spaces for fusion and fixation. Results: Total 6 patients completed 1-year follow-up. The clinical parameters such as Japanese orthopaedic association score (JOA), visual analog scale (VAS) and neck disability index (NDI) were all much significantly improved after surgery. Both C2-7 curvature and segmental curvature were improved after surgery. No obvious complications, including non-fusion, cage subsidence, cage protrusion, or breakage of screws, were observed in all cases. Conclusion: Our preliminary study showed that ACXVP was a safe and effective procedure for segmental cervical spinal stenosis, which could be an alternative operation for ACCF in the future.

1187

P491: Large Osteosarcoma Resection in the Cervical, Paraspinal Region Based on Computer Aided Preoperative Planning and 3d Printed Physycal Model-Case Report and Presentation of the Method

Balazs Szollosi ¹ , Peter E. Eltes ^1,2 , Laszlo Kiss ¹ , Máté Turbucz ² , and Aron Lazary ¹

¹ National Center for Spinal Disorders, Spine Surgery, Budapest, Hungary

² National Center for Spinal Disorders, In Silico Biomechanics Laboratory, Budapest, Hungary

Introduction: Osteosarcoma is the most common malignant bone tumor, spinal involvement accounting for 2-5 % of all osteosarcomas. The treatment of choice is en bloc resection with wide margins combined with adjuvant or neoadjuvant chemo- and radiotherapy. However, en bloc resection of osteogenic sarcomas in the cervical region is seldom feasible due to the surrounding important neural, vascular and visceral organs. Virtual and 3D printed patient-specific physical models have the potential to enlight the unique complex atypical anatomical-geometrical problems caused by tumors. The models not only clarify the geometrical problems but it can improve the outcome of the surgery by preventing complications and reducing surgical time. Materials and Methods: We present acase report with 6-month follow-up (FU) of a 53 years old male patient with huge tumor mass (91 x 125 x 100 mm measured on the CT and MRI scan) in the left paraspinal cervical region, how suffered intolerable neck pain with irradiation in the left upper extremity (VAS = 10), and motor weakness in the left upper extremity. The result of the biopsy was low-grade chondrosarcoma. Fort the safe resection of the tumor based on the pre-op CT the patient-specific virtual geometry was defined by segmentation algorithm. The geometrical accuracy was tested using the Dice Similarity Index (DSI). Based on the segmented geometry a complex 3D virtual plan was created for the surgery. Parallelly the virtual geometry was printed using FDM (Fused Deposition Modeling) technology. Results: Segmentation process provided a highly accurate geometry (cervical spine C3-T1, left clavicula, tumor mass, the manubrium sterni) with a DSI value of 0,95. The virtual model was shared in the internal clinical database in 3D PDF format. The printed physical model was used in the preoperative planning phase, int the patient education/communication and during the surgery. No complication was registered during the surgery. The arteria subclavia and the carotid artery was kept as well as the brachial plexus. The surgery was performed successfully, at the post-op, 3 months FU up and 6 months FU the patient VAS 4 and 2 respectively with god function of the upper extremity. Conclusions: We used the patient-specific 3D virtual and printed physical geometry and computer-aided planning to develop the optimal surgical plan for the en-bloc tumor removal, which was performed successfully. The added value of printed physical model was considered by the surgical team (two senior chief spine surgeon, one chief plastic surgeon) to be high not only in the pre-surgical phase but during the surgery as well. The chosen FDM technology provided an accurate robust and affordable physical model. This case is part of a multicase investigation where we use patient-specific 3D printed physical models in the preoperative planning, patient education, and during the surgery to visualize the complex, unique anatomical situation.

1205

P492: Iatrogenic Spinal Deformity Correction Using Patient-Specific 3D Printed Physical Model and Compute-Aided Preoperative Planning-Case Report

Andras Bank ¹ , Jennifer Fayad ^2,3 , Peter E. Eltes ^1,2 , Máté Turbucz ² , and Aron Lazary ¹

¹ National Center for Spinal Disorders, Spine Surgery, Budapest, Hungary

² National Center for Spinal Disorders, In Silico Biomechanics Laboratory, Budapest, Hungary

³ Università di Bologna, Department of Industrial Engineering, Bologna, Italy

Introduction: Patients with iatrogenic spinal deformities are identified with increasing frequency as the number of instrumented spinal operations increases globally. The deformity correction can be compromised by the complex anatomical /geometrical irregularities due to the previous surgeries. Virtual and 3D printed patient-specific physical models have the potential to illuminate the unique complex atypical anatomical-geometrical problems caused by previous surgical interventions. The models not only clarify the geometrical problems but it can improve the outcome of the surgery by preventing complications and reducing surgical time. Materials and methods: We present acase report with 6-month follow-up (FU) of a 71 years old female patient with severe sagittal and coronal malalignment due to repetitive discectomy, decompression, laminectomy, and stabilization surgery over the last 20 years performed in another hospital. The patient suffered from low back pain (VAS = 9, ODI = 80). Stabilization (Th9- Ileum), alignment correction (pedicle subtraction osteotomy, PSO) was decided as the required surgical treatment. Fort the better understanding of the complex, anatomical situation based on the pre-op CT the patient-specific virtual geometry was defined by segmentation algorithm. The geometrical accuracy was tested using the Dice Similarity Index (DSI). Based on the segmented geometry a complex 3D virtual plan was created for the surgery. Parallelly the virtual geometry was printed using FDM (Fused Deposition Modeling) technology. Results: Segmentation process provided a highly accurate geometry (L1 to S2) with a DSI value of .92. The virtual model was shared in the internal clinical database in 3D PDF format. The printed physical model was used in the preoperative planning phase, int the patient education/communication and during the surgery. The surgery was performed successfully, no complication was registered during the surgery. The measured change in the sagittal vertical axis (SVA) was 7cm, in the coronal plane the distance between the C-7 plumb line and the central sacral vertical line was reduced with 4 cm. In the lumbar lordosis a 33 degree of corection was archived due to the pedicle subtraction osteotomy at the L4 vertebra., at the post-op, 3 months FU up and 6 months FU the patient VAS 4 and 3 respectively with reduction in the ODI at 6m FU to 20 points. Conclusions: We used the patient-specific 3D virtual and printed physical geometry and computer-aided planning to develop the optimal surgical plan for the deformity correction, which was implemented successfully. The printed physical model was considered advantageous by the surgical team in the pre-surgical phase and during the surgery as well. The chosen FDM technology provided an accurate robust and affordable physical model. This case is part of a multicase investigation where we use patient-specific 3D printed models in the preoperative planning, patient education, and during the surgery to visualize the challenging anatomical situations.

1331

P493: The Gain of Segmental Lordosis in the Prone Position

Rodrigo Amaral ¹ , Luiz Pimenta ¹ , William Taylor ² , Antoine Tohmeh ^1,3 , Gabriel Porkony ¹ , and Matheus Batista ¹

¹ Instituto de Patologia da Coluna, São Paulo, Brazil

² University of California San Diego, San Diego, USA

³ Washington University, Spokane, USA

Introduction: The lateral lumbar interbody fusion (LLIF) is a safe and effective technique to treat a vast range of lumbar disorders. The LLIF is a good option for interbody fusion, as it reduces posterior muscle damage, is capable of relief neurological symptoms through indirect decompression, and promotes more significant gains of segmental lordosis than standard posterior techniques. However, the segmental and global gain of lordosis with LLIF is often put in check, with average gains of segmentar lordosis in literature ranging from 3.6° to 0°. We hypothesized that one of the reasons for that small gain is that in lateral decubitus there is not enough space to insert more lordotic cages and that by positioning the patient in a prone decubitus the intradiscal segmentar lordosis would be enhanced. Methods: The inclusion criteria were as follow: Patients undergoing prone transpsoas surgery; patients that had intraoperative fluoroscopy; patients with pre-operative X-rays; and the exclusion criteria as follows: patients with low-quality X-rays or fluoroscopy that does not allow the measures of the required measures. We measured the index level segmentar lordosis of the patients in the X-rays and at the prone position fluoroscopy before cage insertion. The gain of segmentar lordosis was calculated as Prone Position Index Lordosis – PreOp Stand-up X-ray. The difference between the two groups was compared using the T-test with a P < .05 being considered significant. Results: Ten patients were included in the study, and Eleven levels were analyzed (Six L4L5; Four L3L4; 1 L2L3). The mean gain between the prone and stand-up positions was 1.6° (SD: 5.8) with no significant statistical difference among both groups (P = .3). Similar differences among prone and stand position was found in L4L5 level 1.6 (SD: 8.3) with no differences between the groups (P = .6), although after excluding an outlier value from the data, the difference between the groups raised-up to 4.7° (SD:3.1) with statistical significance between the groups (P = .02). When analyzing the L3L4 level there were 1.2 of difference between the prone and stand position (P > .05). Conclusion: The prone position promotes an increase in segmentar lordosis, mainly at L4L5, which may allow the insertion of more lordotizing cages, possibly enabling more significant alignment corrections after lateral transpsoas surgeries.

1393

P494: Teaching Spine Surgery: An Analysis of the Current Data

Mauricio Avila ¹ and Travis Dumont ¹

¹ University of Arizona, Neurosurgery, Tucson, USA

Introduction: Training in spine surgery has classically been a mixture of residency education and postgraduate fellowships. Despite the vast amount of spinal surgical procedures performed worldwide and the growing interest in specialty training little is known on how spine surgery is being taught on a daily basis. Methods: We performed an explorative review of the literature for articles regarding spine education. With particular interest in teaching methods and graduate and postgraduate (fellowship) training. Several keywords were used in combination such as: Education, neurosurgical procedures, anatomic models, spine surgery. Two hundred sixty-two articles were found in English language and after selection, 41 articles were reviewed. Results: The majority of the articles were form the USA (22) followed by Canada (5 articles) and Austria (3). All the articles were published between 2000 and 2018 with the year 2014 having the most articles. The data was published in 17 different journals with the most common being Neurosurgery (Oxford Academic) followed by Spine (Wolters Kluwer) and Acta Neurochirugica. Overall the majority of the articles were published in spine specific journals (6) or Neurosurgical journals (6) and only 2 articles were published in Medical education journals. The majority of the articles were about simulation (including Haptic, cadaver, Virtual reality) followed by surveys-based research from attendings and fellows after the simulation. The most common spine section studied was lumbar, followed by manuscripts discussing all spine section and then the Thoraco-lumbar spine. Overall the participants were satisfied with these training activities and most improved while compared pre and post activity scores. Conclusion: Despite the vats interest in spine surgery there is paucity of research discussing the way to teach and learn spine surgery. Most of the scientific literature found encompass simulation techniques and surveys of practicing surgeons and trainees for different spinal procedures. Despite the few articles available, the results show that the training sessions were of value for the participants. We believe there is a large area of research to improve and incorporate different techniques to teach spine surgery.

1509

P495: Initial Stability and Cage Migration Within Cervical Constructs Using 3D-Printed Generic vs Patient-Specific Interbody Devices for Anterior Cervical Discectomy and Fusion (ACDF): An In-Vitro Study

Melvin Ng ^1,2 , William Parr ^1,2,3 , Tian Wang ¹ , William Walsh ¹ , and Ralph Mobbs ^2,4

¹ Surgical and Orthopaedic Laboratories, University of New South Wales, Sydney, Australia

² NeuroSpine Surgery Research Group, Prince of Wales Private Hospital, Sydney, Australia

³ 3DMorphic Pty Ltd, Sydney, Australia

⁴ Prince of Wales Private Hospital, Sydney, Australia

Introduction: Anterior cervical discectomy and fusion (ACDF) aims to increase disc height and stabilise pathological segments to reduce static and dynamic neurological compression respectively. Poor cage-endplate fit is a potential risk factor for cage migration and excessive motion of fusion constructs, which may result in poor immediate clinical outcomes. Recently, 3D-printed Patient-Specific Implants (PSI) have been used in both human and canine cervical spinal surgery, which aim to improve initial stability of instrumented constructs. Differences in immediate post-operative construct stability and cage migration between PSI and generic “off-the-shelf” (OTS) cages have not been evaluated. We tested these parameters in an in-vitro canine cervical model. Canines are good models for ACDF due to similarities in pathophysiology and surgical technique. This study aims to quantify immediate post-implantation stability and cage migration within single-level constructs instrumented with standalone PSI and OTS ACDF cages, and the effects of endplate preparation on the same parameters in constructs with OTS cages. Material and Methods: An in-vitro, biomechanical study was performed with six canine C6/7 cervical specimens using a 6-axis robotic mechanical testing system and 3D motion tracking. 1Nm pure moment was applied to each specimen in flexion and left and right lateral bending (LB) and axial rotation (AR). The OTS and PSI cages were designed based on 3D reconstructions of computed tomography scans of each specimen, and 3D-printed in Grade 5 Ti alloy. Range-of-motion (ROM), neutral zone (NZ) and cage migration angles were measured in flexion, lateral bending (LB), and axial rotation (AR) in the intact, PSI cage, OTS cage, and OTS cage with endplate preparation (OTS-EP) conditions. Data was analysed with repeated measures ANOVA. Results: All cage conditions significantly reduced LB ROM, and NZ in flexion and LB compared to the intact condition. There were no significant differences between intact and cage conditions in AR ROM, but the PSI showed significantly reduced NZ in AR. There were no significant differences in ROM and NZ between cage conditions. The PSI condition had significantly smaller cage migration angles than OTS and OTS-EP conditions in AR, and the OTS condition had significantly smaller cage migration angles than OTS-EP in LB. Conclusion: PSI devices tended to reduce ROM and NZ motion more than OTS, although differences did not reach statistical significance. A power analysis performed on NZ data showed sample sizes of 14-20 would yield significant differences between these conditions. The present study was limited by a relatively small sample with different dog breeds and sizes, associated with large variance in motion.

1561

P496: The Use of Mesenchymal Stem Cells to Treat Degenerative Disc Disease: A Systematic Review of Animal and Human Studies

Muhammad Malhi ¹ , Roozbeh Shafafy ² , and Sherief Elsayed ^3,4

¹ Brighton and Sussex Medical School, Brighton and Hove, United Kingdom

² Royal National Orthopaedic Hospital, London, United Kingdom

³ Brighton and Sussex University Hospitals, Brighton and Hove, United Kingdom

⁴ NMC Spine, Dubai, United Arab Emirates

Introduction: Back pain, which can be caused by degenerative disc disease (DDD), is a major cause of pain and disability worldwide and confers substantial socioeconomic ramifications. Currently, there is a dearth of evidence regarding the efficacy and safety of mesenchymal stem cells (MSCs) for the regeneration of the intervertebral disc (IVD). This review aims to critically appraise and narratively synthesise evidence from animal and human studies on the use of mesenchymal stem cells (MSCs) to treat degenerative disc disease (DDD). Material and Methods: A systematic search of PubMed, Embase, Science Direct and Cochrane Central Register of Controlled Trials databases as well as Clinical Trials.org, to January 2020, was carried out using predetermined search terms. Bibliographies of published narrative and systematic reviews were also screened to identify other relevant publications. The quality of eligible studies was assessed, and study characteristics and data were tabulated for analysis. Results: From 1680 potentially relevant citations, twenty studies met the inclusion criteria-sixteen studies focused on animal models and four studies involved human participants. 10/16 animal studies reported favourable radiological outcomes; this was based on either restoration of the disc height or enhanced MRI T2 signal intensity following MSC transplantation. All animal studies that incorporated histology (11/16) demonstrated improved histological outcomes. 10/16 animal studies reported positive molecular findings in terms of matrix restoration. Data across the four human studies suggested improvement in pain and function relative to baseline; however, a majority of changes were not deemed to be statistically significant. Safety data was sparse and poorly detailed with 19/20 studies reporting no adverse events relating to MSC transplantation. Conclusion: The overall strength of evidence for the efficacy and safety of MSCs for DDD was low due to inconsistencies in methodological design and outcome parameters, small sample sizes and lack of comparator interventions. The limited findings across animal and human studies continue to support the conjecture that MSCs have regenerative potential that can be safely utilised to treat degenerated discs. Robust animal models that can more closely replicate the human condition and high-quality comparative studies are now needed to assess whether MSCs can truly enhance the armaments at the disposal of the clinician in the treatment of DDD.

1605

P497: On the Future Design of Bio-Inspired PEEK Spinal Implants: Giving Spine Implants a Bony Surface Avoids Inflammatory Reactions and Postoperative Complications

Dietmar Schaffarczyk ¹

¹ stimOS GmbH, Bio-Material Research, Konstanz, Germany

Introduction: To enhance the biological performance of PEEK implants, these materials are mixed with HA or coated with Titanium. But the high risk for patients with these kinds of composites are abrasion and delamination of Ti-nanoparticels, as Ti and TiO₂ is suspected to be toxic and carcinogenic. In the case of medical implants– such as spinal fusion implants – wear debris and ions release produced due to the loss of material by bio-tribocorrosion of implant surfaces have been related to tissue inflammatory reactions. An association between ultrafine TiO₂ (<100 nm in diameter) particles and adverse biologic effects have been reported in the literature. Material and Methods: To avoid risks for the patients associated with the use of Titanium or Titanium composites the authors developed and analyzed a new surface modification technique called Mimicking Bone Technology (MBT) invented to add best osseointegrative characteristics to pure PEEK surfaces. The surface modification technique is not a coating technique but an bio-chemically covalently joined surface functionalization resulting in bone-identic, mineralized PEEK-MBT implant surfaces eliminating the risks of abrasion, wear debris and TiO₂ diffusion. To confirm the results achieved in-vitro, an animal model was conducted to demonstrate that MBT surface modification has unique characteristics designed to support early bone formation and proper implant anchorage. Results: MBT modifications are process-validated technologies. The technology has been subject of statistically significant comparative in-vitro cell tests showing superior results regarding cell adhesion, viability and proliferation compared to PEEK, Titanium and HA-enhanced PEEK materials. PEEK-MBT surface turned out to be the most suitable candidate for healing into the bone tissue among all tested materials due to high osteoblast proliferation and cell adhesion, and due to the most intensive formation of mineralized bone nodules (follow up 12h / 24h). In-vivo, PEEK-MBT demonstrated superiority in osseointegrative characteristics compared to Titanium and HA-enhanced PEEK: Bone in-growth into the implant-screw threads starts with MBT after a 2 week period in time. With MBT a high BIC % can be seen already after two weeks. This is a strong indication for avoiding aseptic loosening. Histologic examination shows:

1. Titanium: Dense new bone is only observed in the upper part of the implant. Screw thread is not filled homogenous with bone. No stable anchorage of implant in the surrounding bone.

2. HA enhanced PEEK: Bone is only observed on one side of the implant: Screw thread is not filled homogenous with bone. No stable anchorage of implant in the surrounding bone.

3. MBTv: Test implant is anchored completely in surrounding (new) bone. Screw thread is fully filled: No fibrotic layer.

4. MBTv: Test implant is anchored completely in surrounding (new) bone. Screw thread is fully filled: No fibrotic layer.

Conclusion: In vitro and in vivo testing demonstrated safety and performance of the implant surface PEEK-MBT. PEEK-MBT showed osseointegrative characteristics that are statistically significant superior to PEEK, HA-enhanced PEEK and Titanium, known as the golden standard for orthopedic materials. The animal model (sheep) and cell tests demonstrated the overall biocompatibility of the new surface modification MBT.

1637

P498: Titanium Coated PEEK Cages: Spinal Fusion Device or Commercial Myth?

Willems Karel ¹ and Amélie Willems ¹

¹ AZ Delta Roeselare, Orthopaedic surgery, Roeselare, Belgium

Introduction: Posterior interbody fusion is frequently used to treat degenerative low back pain. Titanium (Ti) cages are considered the gold standard, but the more elastic PEEK cage seems to result in better clinical and radiological outcome. PEEK is an inert material that does not promote bony ingrowth. Several types of coating have been used to combine the mechanical characteristics of PEEK with a bioactive layer. Ti coating at low temperature and high energy results in coating with a thickness in the submicron range is a dense, non-porous metallic layer on the surface of the implant not harming the micro surface topography, the radiolucency and the elasticity of the implant. An animal study, where long bones of sheep (femur and tibia) were implanted with coated and uncoated dowels, compared the osseo integration of PEEK dowels with that of PEEK dowels coated with CaP or with Titanium. Histology showed direct bone implant contact with the Ti coated and the CaP coated dowels. The surface was covered with bone trabeculae, whereas on the sections of the control PEEK dowel a fibrotic layer was seen between the dowel and the surrounding bone tissue. Comparative impaction tests with PEEK PLIF cages with either no coating, CaP nanocoating or Ti nanocoating showed that the uncoated cages lost .39 mg, CaP nanocoated cages lost .57 mg and the Ti nanocoated cages lost .75 mg.[15] The wear of Ti plasma spray coated cages was 2.02 mg. A randomized controlled, double blind multicenter parallel three arm study the clinical and radiographic outcome of posterior lumbar interbody fusion (PLIF) at one level was assessed for implantations of PEEK cages, with Ti coating (TSC) or CaP coating (osteoCon) or uncoated (reCreo) cages. Materials and Methods: Patients between 18 and 75 years with chronic mechanical low back pain with or without radiation into the leg (>6 months) refractory conservative treatment scheduled PLIF approach utilizing supplemental posterior fixation were randomly assigned to receive implantation of PEEK cages, with Ti coating (TSC) or CaP coating (osteoCon) or uncoated cages. The primary radiological outcome was the implant stability and fusion status assessed with X-ray, standing A/P and lateral radiographs and CT-scan (6-12 months). The CT-scans were evaluated by an independent experienced spine radiologist, blinded to the used spacer. The primary clinical outcome was the evolution from baseline in pain, disability and quality of life. Clinical evaluation was performed pre-operatively, and at 6 weeks, 3 months, 6 months and 12 months. Patients were asked to report pain for the leg and for the back on a 10-point visual analogue scale (0 no pain and 10 the worst imaginable pain), and to fill out the Oswestry Disability Index (ODI) and the SF-36 was used pre-operatively and after 12 months. Results: In the group treated with the Ti nanocoated cages more patients had definite ingrowth at 6 and 12 months. No significant clinical differences between groups were observed. Discussion: Although the clinical outcome was not significantly different between the groups, the higher rate of bony ingrowth is important.

1650

P499: Diaphragm Pacing: Is It Possible to Get Rid of Mechanical Ventilation in Cervical Injury Patients?

Mohit Muttha ¹ , Harvinder singh Chhabra ¹ , and Raymond P Onders ²

¹ Indian Spinal injuries Centre, Spine services, New Delhi, India

² University Hospitals CMC, GI Surgery, Ohio, USA

Introduction: Every year 4% of spinal cord injury (SCI) patients require prolong mechanical ventilation. When compared with an able-bodied 20-year old, the life expectancy for a 20-year-old SCI patient on long-term mechanical ventilation decreases markedly from 58.6 to only 17.1 years. The aim of our work is to study applicability of direct diaphragm pacing in cervical cord injury patients on mechanical ventilation, to provide them early access to complete rehabilitation.[1] Materials and Methods: Diaphragm pacing System (DPS) was developed to replace mechanical ventilation by laparoscopically placed intramuscular diaphragm electrodes, which when stimulated lead to contraction and ventilation. DP functions as a powered muscle stimulator for treating disuse atrophy as well as a functional electrical stimulator to drive respiration. Ours is a single institution study. Direct Diaphragm pacing was done for the very first time in our country. It included review of laparoscopic diaphragm, motor point mapping with electrode implantation and subsequent diaphragm conditioning and ventilator weaning. First patient 45 year old male, operated case of C4-C5 fracture dislocation with AIS A neurology since 16 months. Patient was tracheostomised, presented with increased secretions, higher placed left dome of diaphragm and poor cough reflex. It was difficult to decannulate him. Second patient 53 year old male, case of C3 traumatic tetraplegia with AIS A neurology. Patient had history of gunshot injury 4 years ago which was managed conservatively. Presently patient was on domestic ventilator. Third patient 60 year old male with C7-T1 fracture dislocation in ankylosed spine which was operated 3 months back with C2 to T3 posterior stabilisation. Patient had AIS A neurology. All patients gave informed consent for both the evaluation and the subsequent operative mapping and implantation of DP. Results: First two patients were implanted with DPS. Third patient of ankylosed spine had unstimulable diaphragms on intraoperative trial of stimulation. First patients left diaphragm dome came down immediately; his cough reflex and single breath count improved when on DPS. He was subsequently decannulated within a week. On 15 months follow up he is maintaining well. His cough, speech and olfactory sensation are improved. Second patient was maintaining off ventilator for 2 hours on DPS at 3 months post-surgery. Third patients diaphragm were not stimulable even on maximum intensity. This may have resulted from either phrenic nerve damage or infarction of the involved phrenic motor neurons; he was not implanted. To counter check, his abdominal musculature was stimulated which was contracting. Limitations of study include short term follow-up and small number of patients. Conclusion: Diaphragm pacing system (DPS) is a safe and new technique with potential to improve the quality of life of patients who are dependent on mechanical ventilation due to cervical cord injuries. Earlier implantation leads to greater full time freedom from ventilators.

References

1. National Spinal Cord Injury Statistical Center. Available at: http://www. spinalcord.uab.edu Accessed February 12, 2018

1669

P500: The Use of Postural Wearable Devices in Patients With Lumbar Spinal Pathology: A Qualitative Study With the Lumo Lift Device

Nicole Kah Mun Yoong ^1,2 , Jordan Perring ^1,2 , and Ralph Mobbs ^1,2,3

¹ University of New South Wales, Sydney, Australia

² NeuroSpine Surgery Research Group, Prince of Wales Private Hospital, Sydney, Australia

³ Prince of Wales Private Hospital, Sydney, Australia

Introduction: Poor posture could suggest deep-seated disability, pain and low quality of life. In patients with lumbar spine pathology, a cycle may exist with abnormal posture as abnormal posture is both a contributor to accelerated intervertebral disc degeneration and a behavioural adaptation by patients to alleviate pain and discomfort arising from neurological compression. Current methods of postural analysis are limited to the clinical or laboratory settings, and only capture a snapshot of patients’ postures. Recently, the utility of wearable devices in healthcare is gaining traction with the emerging concept of the ‘quantified self’. Postural wearable devices can measure movement in three dimensions, from which data could potentially be extracted to quantify postural changes in individuals. Furthermore, the constant postural monitoring will enable continuous measurements as opposed to a single-time solitary data collection in a laboratory. Certain wearables such as Lumo Lift can send real-time haptic biofeedback which offers additional motivation and feedback to improve compliance and hence posture. The aim of this study is to investigate the practicality and functionality of commercial postural wearable devices for daily monitoring of posture in patients with lumbar spine pathology using the Lumo Lift posture device (Lumo Bodytech Inc., California, USA). Material and Methods: 30 patients with lumbar spine pathology and 10 healthy controls with no known spinal pathology were recruited and required to use the Lumo Lift posture device for a minimum of six weeks. Semi-structured interviews were conducted in person or over the phone to investigate participants’ experience of use with the device. Thematic analysis and independent parallel coding were carried out using NVivo 12 Pro to assess user experience of the Lumo Lift device. Results: User satisfaction and compliance, and device effectiveness were the main themes identified from the raw interview data. Participants had low user satisfaction and compliance, attributed to poor device performance and difficulties in maintaining consistent device use. There were differences in postural improvements and post-study usage between the control and study groups, with more participants in the latter achieving postural improvements and expressing continuation of Lumo Lift use after the study period. These differences were attributed to existing spinal pathology and differing motivation levels. However, the Lumo Lift device was still deemed to be practical and effective in achieving short-term postural improvements. Conclusion: Our findings suggested user-perceived functionality and practicality of Lumo Lift in daily life was impacted by personal experience. Overall, participants found the Lumo Lift to be functional and practical in monitoring and improvement of short-term posture in spite of flaws in device quality. Commercial wearable devices may prove to reliably measure and record long-term posture and further studies with an alternative device capable of quantitative posture measurements should be considered.

1680

P501: Application of Mixed Reality Technique in the Teaching of Percutaneous Endoscopic Lumbar Discectomy Compared With Conventional Teaching Method

Yu Keyi ¹ and Ziquan Li ¹

¹ Peking Union Medical College Hospital, Orthopaedic, Beijing, China

Objective: To explore the application of mixed reality technique in the clinical teaching of percutaneous endoscopic transforaminal discectomy. Methods: Collaborating with the team of Tsinghua University, percutaneous endoscopic transforaminal discectomy was presented through mixed reality technology. The subjects were selected from the resident doctor and intern in the surgical department of Peking Union Medical College Hospital, and randomly divided into mixed reality group and traditional teaching group (12 for each group), with the age, gender and seniority matched. After clinical teaching, questionnaire surveys and tests of the interactivity, interest, three-dimensional imagination, and understanding of knowledge were performed in two groups. Results: Our study was the first to use mixed reality technology in clinical teaching of percutaneous endoscopic lumbar discectomy by creating virtual-reality and three-dimensional learning situation. There was no significant difference in the understanding of basic knowledge between the two groups, but the mixed reality group had significant advantages in learning initiative, interactivity, interest and three-dimensional imagination. Conclusions: The application of mixed reality in medical teaching has great potential and broad prospects. Visualization, interactivity and three-dimensional imagination could be improved by medical teaching with mixed reality. Mixed reality combined with force feedback technology has significant development prospects of simulation training in specialist physicians.

1681

P502: Operationalizing and Digitalization of Person Centered Spinal Healthcare: FAIR Data and Distributed Learning as a Way Forward

Esther Janssen ^1,2 , Ilona Punt ^1,3 , Johan van Soest ^4,5 , Lodewijk van Rhijn ¹ , Andre Dekker ⁴ , Paul Willems ¹ , and Nico van Meeteren ^6,7

¹ Maastricht University Medical Center+, Department of Orthopedics and Research School Caphri, Maastricht, The Netherlands

² VieCuri Medical Center, Department of Orthopedics, Venlo, The Netherlands

³ Maastricht University Medical Center+, Department of Surgery and Trauma Surgery, Maastricht, The Netherlands

⁴ Maastricht University Medical Center+, GROW-School for Oncology and Developmental Biology, Department of Radiation Oncology (MAASTRO), Maastricht, The Netherlands

⁵ Maastricht University, Institute of Data Science, Maastricht, The Netherlands

⁶ Top Sector Life Sciences and Health (Health∼Holland), the Hague, The Netherlands

⁷ Maastricht University Medical Center+, Department of Epidemiology and CAPHRI Research School, Maastricht, The Netherlands

Introduction: Meeting the challenge of person centered spinal healthcare, requires analysis of big data. Fortunately, an increasing amount of healthcare data on spinal healthcare is collected every day. This data holds a tremendous amount of information that has the potential to revolutionize personalized healthcare. However, the potential of this data has not yet been utilized as it is stored in inaccessible siloes, is hard to understand and interpret by others, leading to a loss of valuable knowledge and suboptimal care. Therefore, a transition towards data-driven spinal healthcare embracing the advances in data science is advocated. The aim of this study was to introduce internationally advocated solutions for making optimal use of standard care data and big data analysis for the optimization of personalized spinal healthcare. These solutions being: FAIR data and distributed learning. Material and Methods: In this study we show how to create FAIR (Findable, Accessible, Interoperable and Reusable) databases of clinical data in patients eligible for elective lumbar spinal fusion surgery. Firstly, non-FAIR data was extracted from patients’ electronic health records. Next, machine readable data was created by creating a relational database. Here data was transformed into semantic triples, using R2RML mapping. This mapping is basically a description of how variables are related to each other so computers can make sense of them. This machine readable data is then published on ‘the web of data’, which means other computers can reach and analyze the data. However, this does not mean it is freely accessible. Via a secured interface this data can be analyzed in a privacy-preserving manner, using distributed learning, which can analyze data without removing them from their original location. A researcher can send any type of analysis via the interface to the data, in return will only get the outcomes of the analysis and not the individual patient data. Results: A relational database was built describing basic relationships in data collected within a clinical context of patients deciding for elective lumbar spinal fusion. Next, each variable of the of the dataset was transformed into semantic triples and was published on the web, so that they could be found and analyzed by computers. We sent an analysis in a machine readable language (SPARQL) to calculate which preoperative variables were related to postoperative recovery. From this analysis results showing the importance of each preoperative variable for predicting postoperative recovery was received, without the sharing of individual data points. Conclusion: Using the proposed technological solutions for structuring and publishing real-world data can greatly improve the potential use of these data. In this example, we showed a simple application in a single dataset, using a single analysis. The key here is that this data can be (re)used very easily for multiple analyses. Moreover, we would like to encourage other reseachers clinics to join this endavour to implement global distributed big data analysis for spinal healthcare. More FAIR databases connected via a distributed data-infrastructure will exponentially increase its usefulness. Thereby, we could make great steps towards person centered spinal healthcare.

1742

P503: Preventing Iatrogenic Facial Pressure Ulcers During Spinal Surgery - Prospective Trial Using a Novel METHOD

Shahnawaz Haleem ¹ , Ruxandra Mihai ² , Dominique Rothenfluh ³ , and Jeremy Reynolds ³

¹ Royal Orthopaedic Hospital, Spinal Surgery, Birmingham, United Kingdom

² Nuffield Orthopaedic Centre, Anaesthesia, Oxford, United Kingdom

³ Nuffield Orthopaedic Centre, Spinal Surgery, Oxford, United Kingdom

Introduction: To assess the outcome of a novel method of preventing facial pressure ulcers in spinal surgery and a review of literature. Material and Methods: A prospective trial using a novel method of facial protection using paraffin tulle gras dressing to cover bony prominences during spinal surgical procedures was performed. Patients were reviewed at 24 hours and 6 weeks. A telephone survey was also conducted post discharge. Results: Over an 8-month period, 12 patients (7F:5M, age 9-72 years) underwent spine surgery for tumour stabilisation (n = 7), deformity correction (n = 4) and degenerative presentation (n = 1) with mean operative time of 472 minutes (range 150 – 785 minutes) in prone position. All patients were managed by the same team using an agreed protocol. No pressure ulcers were noted in our study. One patient sustained minimal erythema which resolved after 24 hours. All patients were satisfied with the care received. Conclusion: Facial pressure ulcers though much reduced are still common in spinal surgery. The common factors are the long duration of surgery, shear, friction, moisture and intrinsic factors. Our strategy of an appropriate facial support and constant vigilance helped eliminate the incidence of iatrogenic facial ulcers in spinal surgery.

1795

P504: What Are the Patients With Column Pathology Looking for in Internet?

Maria Luz Suarez-Huerta ¹ , Haridian Helena De Armas Baez ¹ , Alejandro Gomez-Rice ¹ , Iria Carla Vazquez-Vecilla ¹ , Miguel Carvajal-Alvarez ² , and Lorenzo Zuñiga-Gomez ¹

¹ Hospital Universitario De Getafe, Madrid, Spain

² hospital Universitario De Cabueñes, Spain

Introduction: The search for medical information is very frequent today. The Internet represents a space for information, communication and action on health. This supposes a transformation of the healthcare practice and the habits of our patients, beginning to appear the terms of eHealth and informed patient. Material and Methods: This is an observational study of patients between 18 and 70 years old who were seen in the spine unit consultation from October 1 to November 29, 2019. Sociodemographic variables, treatments, complications and Internet search habits (pages, frequency and information) were collected. A statistical analysis is performed with SPSS v22.0 software. Our objective is to know the habits of our patients when consulting medical information on the Internet. Results: We have included 109 patients, 51% were women, the mean age was 50 years and the BMI was 28. 73% of patients use the Internet daily, 90% of these through their mobile phone. Men in our series use mobile phones more than women (P: .03) and young people often consult medical information in Blogs (P: .01). The most visited pages are news (29%) and only 10% have never looked for medical information. 51% have searched about their spinal pathology and only 7% admit having sought information about their doctor. 67% of our patients refer that the information obtained has not modified the trust they have in their doctor. Conclusion: The use of the Internet from the mobile phone to consult health information is very frequent, but patients tend to use little the pages of medical and scientific societies.

Spine Biologics

576

P505: Mesenchymal Stem Cell Therapy for Traumatic Spinal Cord Injury - Is the Hype Worth the Hope?

Sathish Muthu ^1,2 and Madhan Jeyaraman ^1,3

¹ Orthopaedic Research Group, Coimbatore, India

² Government Hospital, Velayuthampalayam, Karur, India

³ Sharda University, School of Medical Sciences and Research, New Delhi, India

Introduction: Several preclinical studies and clinical trials have revealed that stem cells can be used to repair spinal cord injury (SCI) because of their self-renewal property and capacity for neuronal-like differentiation into a functional neural cell to form new synapses, release various neurotrophic factors, and provide an appropriate conducive microenvironment to promote neuronal repair. Although the reliability of such treatment methodology for SCI is being tested in human subjects by a few clinical trials, they provide us with conflicting results and thereby clouding the only ray of hope for SCI patients. Hence, we aim to analyze the evidence in literature on efficacy and safety of Mesenchymal Stem Cell(MSC) therapy in human subjects with traumatic Spinal Cord Injury(SCI) and identify its potential role in the management of SCI. Materials and Methods: We conducted independent and duplicate electronic database searches including PubMed, Embase and Cochrane Library till May 2020 for studies analyzing efficacy and safety of stem cell therapy for SCI. AIS grade improvement, ASIA sensorimotor score, activities of daily living score, residual urine volume, bladder function improvement, SSEP improvement and adverse reactions were the outcomes analyzed. Analysis was performed in R-platform using OpenMeta[Analyst] software. Results: 19 studies involving 670 patients were included for analysis. On analysis intervention group showed statistically significant improvement in AIS grade (P < .001), ASIA sensory score (P < .017) along with light-touch (P < .001) and pinprick (P = .046), bladder function (P = .012), residual urine volume reduction (P = .023) and SSEP improvement (P = .002) respectively. However, no significant difference was noted in motor score (P = .193) and activities of daily living score (P = .161). Although intervention group had significant increase in complications (P < .001), no serious or permanent adverse events were reported. On subgroup analysis, low concentration of MSC (<5 x 107 cells) and initial AIS grade-A presentation showed significantly better outcomes than their counterparts. Conclusion: Our analysis establishes the efficacy and safety of MSC transplantation in terms of improvement in AIS grade, ASIA sensory scores, bladder function and electrophysiological parameters like SSEP compared to controls, without major adverse events. However, further research is needed to standardize dose, timing, route and source of MSCs used for transplantation.

1021

P506: A Multicentered Randomized Prospective Double-Blind, Placebo-Controlled Trial on the Clinical Outcomes Using Capacitively Coupled Electric Fields Stimulation After Instrumented Spinal Fusion

Leo Massari ¹ , Giovanni Barbanti Bròdano ² , Stefania Setti ³ , Gaetano Caruso ¹ , Enrico Gallazzi ⁴ , Simona Salati ³ , and Marco Brayda Bruno ⁴

¹ Orthopaedic Institute of University, Ferrara, Italy

² Rizzoli Orthopaedic Institute, Bologna, Italy

³ IGea Spa, Research and development, Carpi, Italy

⁴ Galeazzi Orthopaedic Institute, Spine Surgery III, Milan, Italy

Introduction: Lumbar Spine Fusion (LSF) is used to treat lumbar degenerative disorders. Methods to improve the functional recovery of patient undergoing LSF is one of the main goals in daily clinical practice. The objective of this study is to assess whether biophysical stimulation with Capacitively Coupled Electric Fields (CCEF) can be used as adjuvant therapy to enhance clinical outcome in Lumbar Spinal Fusion (LSF)-treated patients. Material and Methods: Forty-two patients undergoing LSF were assessed and randomly allocated to either the active or to the placebo group. Follow-up visits were performed at 1, 3, 6, 12 months after surgery; long term follow-up was performed at year 10. Visual Analogue Scale (VAS), the Oswestry Disability Index (ODI) and the 36-item Short Form Health Survey (SF-36) questionnaire were recorded. Results: This study demonstrates a significant improvement in CCEF-treated patients at 6 and 12 months follow-up for SF-36, and at 12 months follow-up for ODI values. Based on SF-36 and ODI scores, we reported a significantly higher percentage of successful treatments at 12 months in the active compared to the placebo group. Moreover, in a subset of patients at 10 years follow-up a significant difference was reported in VAS and ODI scores between groups. Conclusion: The results demonstrate that 3 months of CCEF treatment immediately after surgery is effective in reducing ODI and improving SF-36 score, and that these benefits can be maintained up to 12 months. In a subset of patients, these positive outcomes are retained up to 10 years. This study suggests that CCEF stimulation can be used as an adjunct to LSF for spine diseases, for increasing overall Quality of Life and improving patients’ functional recovery. CCEF is safe and well tolerated, compatible with activities of daily living.

1056

P507: Use of Narcotic After Spine Surgery: A Requirement or a Privilege

Muhammad Tahir Karim ¹ , Shahid Ali ¹ , and Sheharyar Abid ¹

¹ Jinnah Hospital, Department of Orthopaedic Surgery, Lahore, Pakistan

Background: There is a growing concern that the use of prescription opioids following surgical interventions, including spine surgery, may predispose patients to chronic opioid use and abuse. Deyo et al. found out that rates of opioid prescribing in the US and Canada are two to three times higher than in most European countries. This ratio is even higher when compared with Asian countries. Limited or no data exist evaluating risk factors associated with prolonged opioid use following spine surgery. We sought to estimate the proportion of patients who didn’t need to use opioids after the end of 1^st prescription following common spinal surgical procedures and were needlessly given narcotics for prolonged periods of time. Objective: The purpose of this study was to find out if the narcotic analgesics are really required as much as they are usually prescribed after spine surgeries or do they just work as a privilege for the patients and the surgeon. Study design/setting: This is a retrospective observational study. Methods: The study utilized the data of patients operated in a major Tertiary Care Hospital in Lahore from October, 2019 to June, 2020. Adults who underwent 1 of 4 common spinal surgical procedures (discectomy, decompression, lumbar posterolateral fusion or lumbar interbody arthrodesis) were identified. Patients with causes of pain other than spine were excluded from the study. Patients were discharged on Tab Tonoflex-P® [Paracetamol:325mg, Tramadol (HCl):37.5 mg] twice daily per oral for 2 weeks after discectomy or decompression surgeries and for 4-6 weeks after lumbar fusion surgeries. Patients were asked about the need of narcotics use after the specified period of time. The collected data was then analysed in SPSS v25.0. Results: This study included 89 patients. About 88% of the patients didn’t feel the need to continue the narcotic pain killers after 1^st post-operative prescription. Less than 12% of the subjects required to continue the narcotics after the end of their first prescription. Conclusion: By the end of 1^st prescription after spine surgery, nearly all patients had discontinued opioid use. These results indicate that spine surgery among opioid-naive patients is not a major driver of long-term prescription narcotics use especially in Asian countries like Pakistan. On the contrary, these narcotics are luxuriously given to patients in the western countries. Main reasons being the bill of these medicines covered by health insurances and lesser efficacy of narcotics analgesics in their general population due to more prevalent alcohol intake and dependence or addiction of drugs.

1079

P508: Functional Outcomes of Loupe Assisted Discectomy in Patients With Lumbar Disc Herniation

Sheharyar Abid ¹ , Shahid Ali ¹ , and Muhammad Tahir Karim ¹

¹ Jinnah Hospital, Department of Orthopaedics, Lahore, Pakistan

Background: Although the short-term results of lumbar discectomy are excellent when there is a proper patient selection, the reported success rates in the long-term follow-up studies vary, and few factors have been implicated for an unsatisfactory outcome. Literature review shows that most of the available data have great clinical and methodological variations and the authors use different outcome assessment tools for different types of lumbar discectomy procedures. Objective: To evaluate the efficacy of loupe-assisted discectomy in patients with lumbar disc herniation. Study design: It is a retrospective observational study. Methods: The study took data from 61 consecutive patients of herniated lumbar disc who were operated by the same surgeon over the period of 1 year. Patients with spinal canal stenosis, previous history of lumbar disc surgery and patients with multilevel disc herniation were excluded from the study. Using the Modified Macnab’s Criteria (MMC), the long-term functional outcomes i.e. ability to return to normal work were assessed at 6 months follow up. Results: Out of 61 patients, 95% reported no pain or restriction of mobility at 6 months follow up and hence, fell in Excellent category of the MMC. Only 5% of the patients reported occasional non-radicular pain and fell in Good category of the MMC. None of the subjects were still handicapped or reported continued objective symptoms of root involvement after the surgery. Conclusion: The long-term results of loupe assisted lumbar discectomy are substantial. About 95% of the patients had excellent results and were able to routine physical activity without any limitation. Only 5% of the subjects complained of mild occasional pain which didn’t interfere with their activities. Not a single patient were still disabled or failed to get benefit from the surgery. Heavy manual work, particularly agricultural work, and low educational level were negative predictors of a good outcome. These indicators should be used preoperatively to identify patients who are at high risk for an unfavourable long-term result.

Surgical Complications

19

P509: Therapeutic Application of Fibrinogen in Spine Surgery; A Systematic Review

Bardia Barimani ¹ , Philippe Moisan ¹ , Carlo Santaguida ² , and Michael Weber ³

¹ McGill University, Orthopedic Surgery, Montreal, Canada

² Montreal Neurological Institute, Montreal, Canada

³ Montreal General Hospital, Orthopedic Surgery, Montreal, Canada

Introduction: Fibrinogen is a glycoprotein complex synthesized in the liver and is converted by thrombin to fibrin and eventually a fibrin clot. Fibrinogen levels are invaluable in the hemostasis process and a deficiency can lead to serious complications during major surgery such as spine surgery. Fibrinogen supplementation has been shown to reduce hemorrhage. The aim of this review is to investigate current hemostatic role of fibrinogen in surgery and see how this can be translated to use in spine surgery. Methods: MEDLINE (via Ovid 1946 to 1/June/2020) and Embase (via Ovid 1947 to 1/June/2020) were searched for relevant studies. The search strategy used text words and relevant indexing to identify articles discussing the use of fibrinogen to control surgical blood loss. The original literature search yielded 407 articles from which 68 duplications were removed. 339 abstract and titles were screened. Results were separated by surgical specialty. Conclusion: Multiple studies have looked at the role of fibrinogen for acute bleeding in the operative setting. It is often safely used in cardiovascular surgery where multiple authors have demonstrated reduced post-operative hemorrhage. There is very little evidence regarding the use of fibrinogen concentrate in Spine surgery even though this is a field with the potential of severe hemorrhage. Further trials are required to understand the utility of fibrinogen concentrate as a first line-therapy in Spine surgery and also to understand the importance of target fibrinogen levels and subsequent dosing and administration to allow recommendations to be made in this field.

86

P510: Current Status of the Oral Hygiene in Spine Surgery Patients

Yushi Hoshino ^1,2 , Yoshifumi Kudo ² , Ichiro Okano ² , Akira Adachi ¹ , Itaru Kawashima ¹ , Hiroshi Maruyama ² , Yoshinori Imaizumi ¹ , and Tomoaki Toyone ²

¹ Asahi University Hospital, Department of Orthopedic, Gifu, Japan

² Showa University Hospital, Department of Orthopedic, Tokyo, Japan

Introduction: In spine surgery, complications such as surgical site infections and postoperative pneumonia can lead to serious medical conditions, and prevention is extremely important. It has been reported that maintaining a good oral environment is important for the prevention of surgical site infection and postoperative pneumonia. However, there are no reports on the actual status of the perioperative oral environment in patients undergoing spine surgery. In this study, we investigated the oral environment of spine surgery patients who received perioperative oral care, including severe periodontal disease and dental caries. Material and Methods: A total of 121 cases of spinal surgery under general anesthesia performed at our hospital between June 2019.and September 2020.A total of 121 cases of spinal surgery under general anesthesia in which perioperative oral care was performed in our dental and oral surgery department were reviewed retrospectively. The oral environment assessment was reviewed by our dentist for the number of remaining teeth, severe periodontitis (periodontal pockets greater than 6 mm), number of caries, and presence or absence of a dental care provider. Results: Mean age: 66.1 years, sex: 59 males, 62 females; surgical site: 12 cervical spine, 8 thoracic spine, 101 lumbar spine; disease: 62 lumbar spinal stenosis, 30 lumbar disc herniations, 13 spinal fractures, 11 cervical myelopathy, 3 thoracic myelopathy, 2 others and 89 patients had a dental clinician. Number of remaining teeth: 12 patients had less than 20 teeth (9.9%), severe periodontitis: 34 patients had periodontal pockets of 6 mm or more (28.1%), caries: 38 patients had one or more caries teeth (31.4%), and 83 patients had a dental care provider (68.6%). When the age groups aged 70 years and older and those aged under 70 years were compared, the number of remaining teeth tended to be lower in those aged 70 years and older, but there was no significant difference in the number of patients with severe periodontal disease, caries and dental care provider. No significant differences were found between caries and severe periodontal caries when comparing with patients with and without a dentist. Comparing age groups, the incidence of periodontal disease was higher in the 40s, while dental caries was found in all age groups. Discussion: Severe periodontitis and caries were found in about 30% of patients undergoing spine surgery. Because periodontal disease was more common in middle age and later, and caries was found in all age groups, perioperative oral care should be provided to all age groups, not just the elderly. Even if a patient is seen in a dental clinic, the oral hygiene environment is not always good in many cases, and all patients need to be closely monitored for perioperative oral environment. Conclusion: Severe periodontitis and dental caries were present in 28.1% and 31.4% of the patients, respectively. There was no significant difference in the prevalence of severe periodontitis and dental caries between patients with and without a primary dentist. By age group, periodontal disease was more prevalent after 40 years of, while caries was found in all age groups.

88

P511: Effectiveness of Prophylactic Metoclopramide in Postoperative Nausea and Vomiting (PONV) After Posterior Lumbar Surgery

Yushi Hoshino ^1,2,3 , Yoshifumi Kudo ³ , Ichiro Okano ³ , Hiroshi Maruyama ³ , Akira Matsuoka ³ , Ryo Yamamura ³ , Yusuke Dodo ³ , Toshiyuki Shirahata ² , Yoshinori Imaizumi ¹ , and Tomoaki Toyone ³

¹ Asahi University Hospital, Department of Orthopedic, Gifu, Japan

² Showa University Koto Toyosu Hospital, Department of Orthopedic, Tokyo, Japan

³ Showa University Hospital, Department of Orthopedic, Tokyo, Japan

Introduction: Postoperative nausea and vomiting (PONV) occurs in approximately 30% of patients after spinal surgeries. PONV causes discomfort, prevents early ambulation, and greatly lowers patient satisfaction; further, its prevention is difficult. Purpose of the study: To examine the prophylactic effect of metoclopramide intravenously administered to patients just after posterior lumbar surgery. Material and Methods: We included 238 patients (141 men; mean age: 65.6 years) who underwent posterior lumbar surgery under general anesthesia at our hospital between April 2014 and January 2019. Posterior lumbar decompression and posterior lumbar interbody fusion were performed on 164 and 74 patients, respectively. These patients were divided into two groups: 158 without prophylactic metoclopramide (no-treatment group; between April 2014 and September 2017) and 80 with prophylactic metoclopramide (treatment group; between October 2017 and January 2019); the effectiveness of prophylactic administration was compared. Metoclopramide (10 mg) and physiological saline (50 mL) were intravenously administered to the treatment group just after their post-surgery return to the hospital room under general anesthesia. No significant difference was noted between the groups in terms of sex, age, and procedure. Occurrence of PONV was examined in these patients. Further, we compared sex, smoking habit, surgical time, and the Apfel score (female sex, non-smoker, history of motion sickness/PONV, and post-surgery opioid treatment) between the groups. Results: Incidence of PONV in the no-treatment and treatment groups was 36.1% and 26.3%, respectively. Although no significant difference was noted, the incidence decreased by approximately 10% in the treatment group compared with that in the other group. No significant difference was noted in the incidence of PONV between the groups in terms of sex, smoking habit, surgical time, and procedure. When we investigated the moderate risk group by the Apfel score, the incidence of PONV in the no-treatment and treatment groups was 35.7% and 11.8%, respectively, indicating a significantly lower incidence of PONV in the treatment group. Discussion: PONV occurs in approximately 30% of patients who underwent spinal surgeries, which is not a low complication rate of surgery. Although metoclopramide is often used after the occurrence of PONV, evaluation of its prophylactic effect remains controversial. In this study, metoclopramide showed prophylactic effect in patients with moderate risk of PONV. The occurrence of PONV may be reduced by selective administration of metoclopramide. The administration method and dose should be examined to obtain further prophylactic effect. Conclusion: No significant difference was observed with metoclopramide use, although prophylaxis after posterior lumbar surgery reduced the incidence of PONV by approximately 10%. Prophylactic metoclopramide was effective in patients at a moderate risk of PONV.

93

P512: Endovascular Therapy for Iatrogenic Left Vertebral Artery Injury After Spine Surgery: A Case Report

Daniel Campos- Irigoyen ¹ , Elias Moussi Saad ² , Cristian Emmanuel De la Rosa Cobián ¹ , and Jose Antonio Vivar Fernandez ³

¹ Instituto Mexicano Seguro Social, Traumatologia & Ortopedia, Mexico, Mexico

² Universidad Anahuac Cancun, Facultad De Medicina, Cancun, Mexico

³ ISSEMyM, Cirugia General, Mexico, Mexico

Introduction: Iatrogenic vertebral artery injury is a rare complication reported in less than .5% of all cervical spine surgeries. Only mild symptoms appear when local minimum metabolic requirements are met. However, if severe enough, vertebral artery injuries may lead to vertebrobasilar ischemia, presenting with multiple, non-specific clinical manifestations, such as neuropathic pain, paresthesia and paraparesis. Thus, diagnostic angiography with endovascular treatment remains the therapeutic keystone in improving the clinical outcome of the patients. Material and Methods: A case report presenting current diagnostic and therapeutic nuances. Results: A 73-year-old male complaining of right-hand numbness presented to an outside clinic for a C5-C7 anterior cervical discectomy and fusion. During the procedure, a concern for a left vertebral artery injury arose; consequently, the patient was taken to the angio suite for an urgent stent placement. Post-operative angiographic evaluation revealed a significant stent-to-vessel size mismatch. The patient was then transferred to our facility. Upon patient’s arrival, neurosurgery was consulted for neck pain and unremitting right hand numbness. A second angiography revealed persistent filling of the pseudoaneurysm at the V2 segment with an undersized-occluding stent. This finding was later confirmed with a cone beam computed tomography. After a thorough evaluation, it was decided not to expand the stent any further, but rather to go outside the stent and perform a glue angioplasty followed by new stenting using a distal filter protection. The occluding stent was pushed medially and the pre-dilatation balloon was fully inflated. A new WALLSTENT® was advanced and centered around the pseudoaneurysm, covering the previous stent. Another two balloon angioplasties were performed. The final angiogram runoff revealed adequate recanalization with less than 20% residual stenosis and no tortuosity. At a two-month, follow-up visit, the patient showed signs of initial clinical improvement. A six month control angiography revealed no evidence of filling of the pseudoaneurysm and a patent wall stent within the left vertebral artery; by that time, the patient had full clinical recovery, with no neck pain nor swallowing difficulty. Conclusion: Iatrogenic vertebral artery injury is a rare, yet potentially fatal complication of cervical spine surgery, that appears with a broad spectrum of non-specific symptoms, thus requiring a high degree of suspicion for early recognition and prompt endovascular treatment.

178

P513: Chance Fracture Pattern Presenting in Proximal Junctional Failure: A Case Series

Jonathan N. Sembrano ¹ , Shea Comadoll ¹ , Michael Schmitz ² , Kenneth Holton ¹ , Christopher Martin ¹ , and David Polly ^1,3

¹ University of Minnesota, Department of Orthopaedic Surgery, Minneapolis, USA

² University of Minnesota, Medical school, Minneapolis, USA

³ University of Minnesota, Department of Neurosurgery, Minneapolis, USA

Introduction: Proximal junctional failure (PJF), a severe form of rostral junctional pathology, is likely to present with instability, neurologic compromise and severe pain often warranting revision surgery. One rare variant of proximal junctional fractures which leads to PJF is a Chance-type proximal junctional fracture occurring at the level of the upper instrumented vertebra (UIV). Material and Methods: Single institution retrospective review of non-consecutive patients who underwent spinal fusion for adult spinal deformity, developed proximal junctional failure (PJF) within 6 months. Patients who developed early PJF underwent a CT scan to assess for a Chance-type proximal junctional fracture. Results: 15 patients were identified, 11 F and 4 M. Average patient age at index surgery was 61.4 yrs (39-77). Average time between index surgery to identification of fracture was 25.4 days (3-65). Average number of levels instrumented was 5.6 (2-15). No antecedent high energy trauma was reported. Radiographs showed increased proximal junctional angle and UIV cephalocaudal pedicle widening. Confirmatory CT scan showed a fracture extending through the long axis of the upper instrumented pedicle, with the cephalad fragment and the superior articular process displaced superiorly. 13 of the 15 patients have undergone proximal extension of fusion. Pedicle screws at the fracture level were either removed or salvaged by changing to an anatomic trajectory. In 10 of 15 (66%) cases the fracture was not identified on postoperative radiographs by the reading radiologist. Conclusion: This case series describes a Chance-type fracture pattern that is often missed on plain radiographs and is a potential cause of early PJF. Continued or increased pain, combined with lateral radiographs showing increased proximal junctional angle and cephalocaudal pedicle widening at the upper instrumented vertebra should raise suspicion for this unique fracture pattern. Obtaining a CT scan is highly recommended, with specific focus on the pedicles and facets. Surgeons and radiologists should be aware of this potentially missed cause of PJF.

281

P514: Perception of Complications by Spine Surgeons

Alfredo Guiroy ¹ , Jeferson Dedéa ² , Asdrubal Falavigna ² , and Giovanni Barbanti Bròdano ³

¹ Spanish Hospital, Orthopedics, Mendoza, Argentina

² University of Caxias do Sul, Caxias do Sul, Brazil

³ Rizzoli, Orthopedics, Bologna, Italy

Introduction: The perception of major versus minor complications may vary according to surgeons, institutions and different specialties. The present study aims to analyze the geographic distribution of the types and severities of the most frequent complications in spinal surgery and to analyze the perception of spine surgeons about postoperative complications. Methods: We developed a questionnaire encompassing clinical scenarios regarding the surgeon’s perception of spine surgery complications. A survey was performed with the members of AOSpine Latin America from January 28^th 2017 to March 15^th 2017. The main variables studied were: specialty, age, years of experience, country, surgeon’s perception of different clinical scenarios, and the surgeon’s classification in each scenario as major, minor or no complications. The results from Latin America (LA) were analyzed and compared to North American (NA) responses. Results: Of the 708 questionnaires answered, orthopedic surgeons represented about 58.2% (n = 412). The most experienced professionals (> 10 years) corresponded to 45.6% (n = 323). The countries analyzed were Brazil (31.5%), Mexico (17.5%), Argentina (14.4%), Colombia (8.0%) and Venezuela (7.6%). Among the data collected in the survey, 4 of the 11 scenarios showed consensus in the results, with the average being over 82.5%. The consensus tendency is present in 45.4% of the clinical cases. Only 2 out of 11 clinical cases did not present a consensus among surgeons. The perception of complications is similar between cohorts (LA 85% vs NA 80%). Conclusion: Significant consensus in the perception of complications was observed in most of the analyzed scenarios. A thorough understanding of methods of perception and analysis of complications tend to provide better data to guide future research.

286

P515: Syringo-Subarachnoid Shunt as Complementary Treatment for Delayed Neurological Deficit in CIM Associated Syringomyelia

Humberto Madrinan ¹ , Luis C Avellaneda ² , Miguel Ruiz - Barrera ¹ , Marco A Rojas ² , and Javier M Saavedra ^1,2

¹ Center for Research and Training in neurosurgery - CIEN, Neurosurgery, Bogota, Colombia

² Hospital Regional de la Orinoquia, Neurosurgery, Yopal, Colombia

Introduction: Syringomyelia is frequently associated to Chiari I malformation (CIM). Foramen magnum decompression (FMD) is the mainstay of treatment for CIM which may often improve syringomyelia. However, treatment failure for syringomyelia following FMD has been reported in up to 50% of the patients for which treatment options remain controversial. We report the case of a patient treated with a syringo-subarachnoid shunt (SSS) after delayed failure of FMD in CIM. Material and Methods: A 38-year-old male, with history of extradural FMD for CIM in 2011, presented with worsening headache, severe spastic quadriparesis, and sphincter dysfunction (Karnofsky performance score [KPS] 40%). Craniospinal MRI revealed holocord syringomyelia and descended cerebellar tonsils. The patient underwent intradural FMD with suboccipital craniectomy extension, posterior arc of C1 resection, C2 laminectomy and duroplasty with heterologous graft. Self-care independence and ability to walk were recovered (KPS 70%) and MRI revealed a very important syrinx contraction. At four months the patient presented a right hip fracture requiring surgery and at 12th-month follow up progressive neurologic deterioration was found (KPS 40%). Syringomyelia had not changed on comparative MRI evaluation and after ruling out other possible causes, the patient was elected to undergo a cervical syringo-subarachnoid shunt through a C4-C5 laminoplasty and dorsal midline myelotomy. Results: The Chicago Chiari Outcome Scale (CCOS) and Asgari score were applied during the first evaluation, after intradural FMD and after SSS with scores of 6, 12, 11 and 10, 5, 7, respectively. After SSS no complications were reported, partial improvement of strength was detected on follow up. Conclusion: Direct syrinx drainage constitutes an option for treating persistent or increasing syringomyelia following FMD for CIM. Thorough clinical evaluation may prompt syrinx drainage even in the absence of radiological deterioration. In our case SSS was indicated based on progressive neurologic deterioration. CCOS and Asgari scores revealed favorable outcome.

310

P516: Comparison of Bazaz Scale, Dysphagia Short Questionnaire and Hospital for Special Surgery-Dysphagia Inventory for Assessing Swallowing Function After Anterior Cervical Spine Surgery

Guoyan Liang ¹ and Yunbing Chang ²

¹ Guangdong Provincial People's Hospital, Spine Department, Guangzhou, China

² Guangdong Provincial People's Hospital, Spine Department, Guangzhou, China

Introduction: Dysphagia is one of the most common complications after anterior cervical spine surgery, but there is no consensus for its evaluation. The Bazaz scale, the Dysphagia Short Questionnaire (DSQ), and the Hospital for Special Surgery-Dysphagia and Dysphonia Inventory (HSS-DDI) were developed specifically for this patient population. However, the psychometric properties of these scales have never been compared. In this prospective diagnostic test study, we evaluated and compared the reliability and validity of these surveys in order to find the most suitable tool for the evaluation of swallowing function after anterior cervical spine surgery. Material and Methods: 150 consecutive patients were prospectively evaluated after anterior cervical spine surgery with the Bazaz scale, DSQ, HSS-DDI, and M.D. Anderson Dysphagia Inventory (MDADI). The reliability and validity of Bazaz scale, DSQ, and HSS-DDI were compared. Receiver operating characteristic (ROC) curves of the DSQ, Bazaz scale, and HSS-DDI were constructed using the MDADI as a reference criterion, and the areas under the curve (AUCs) were analyzed. Results: All surveys were significantly correlated with each other. The HSS-DDI and HSS-Dysphagia subscale showed near-perfect reliabilities (Cronbach α = .969 and .957, respectively). The ROC curves showed that both the HSS-DDI and HSS-Dysphagia subscale had better accuracies (AUCs > .9) than the Bazaz scale and the DSQ for the diagnosis of both mild dysphagia and moderate/severe dysphagia. Conclusion: The HSS-Dysphagia subscale achieved the best efficiency and was most suitable for widespread use for diagnosing dysphagia after anterior cervical spine surgery. The Bazaz scale, by contrast, was considered inaccurate and was not recommended for use.

329

P517: Peri-Operative Complication Rate of Surgically Implanted Paddle Spinal Cord Stimulators

Christian Ivan Lucas Fras ¹ , Sebastian Fras ¹ , and Christian Fras ¹

¹ Institute for Spinal Surgery, Broomall, USA

Introduction: Paddle spinal cord stimulators (SCS) are increasingly being considered for treatment of back and extremity pain. An interdisciplinary approach to treating these patients is needed, with pain management specialists, psychologists, and surgeons working in concert to maximize outcomes. Complications associated specifically with the surgical implantation of paddle SCS have not been extensively reported. The purpose of this study was to evaluate the incidence of complications associated with the surgical implantation of paddle SCS, particularly peri-operative complications. Materials and Methods: 95 consecutive patients were identified who had undergone permanent surgical implantation of a paddle lead SCS. Hospital records, and office charts were examined on all 95 patients to identify any complications within the first 90 days after surgery. Particular attention was paid to identification of any post-operative neurologic deficits, as well as wound healing problems, infection, and implant migration, as well as any other complication. Comorbidities, including smoking, diabetes, pre-operative neurologic deficit, etc, were also noted. Results: Among the 95 consecutive patients, 15 were diabetic, and 20 were cigarette smokers. No patients had pre-operative neurologic deficits. There were 2 cases of superficial wound infection, successfully treated with oral antibiotics alone; these two cases occurred in non-diabetic smokers. There were no deep infections, no post-operative neurologic deficits of any kind, and no cases of implant migration. There were no other complications, including no cases of DVT, UTI, cardiopulmonary complication, dural tear, etc. Conclusion: Surgically implanted paddle SCSs can be safely implanted, with low risk of complication. While anatomical considerations demand attention for the possibility of catastrophic complications, including severe spinal cord injury, no such complications occurred in this cohort of patients. In this study, the overall complication rate was less than 3 percent, and was comprised of only relatively minor complications. Thus, patients may be reassured that paddle SCSs may be surgically implanted with a low risk of peri-operative complication.

471

P518: Modified Frailty Index - A New Tool to Predict Adverse Outcomes and Complications Based on a Study of Lumbar Fusion Surgery for Primary Degenerative Disorders

Pramod Sudarshan ^1,2 , Gowrishankar Swamy ² , and Pradeep Kumar ¹

¹ Aster MIMS, Calicut, India, ² People Tree Hospitals, Bangalore, India

Introduction: Higher rates of adverse outcomes and complications are reported in elderly patients undergoing lumbar fusion for spinal degenerative disorders. Risk stratification based on the age of the patient is not ideal as age is not an independent predicting factor. Predicting the events following surgery preoperatively using Frailty index has been followed in several surgical fields, but not widely in spine surgery. We analyzed the efficacy of modified frailty index (mFI) as a predictor of adverse outcomes and its effect on functional outcomes in lumbar fusion. Material and Methods: All adult patients undergoing lumbar fusion at our centers between 2014 and 2020 were included and studied retrospectively. Postoperative complications, hospital stay, reoperations and mortality rates were assessed. The mFI was calculated, and statistical analysis was performed. Results: 140 patients were included in the study. The mean mFI was .11 (0-.63). Increasing mFI score was associated with increased complications, reoperations and hospital stay (P < .05). With mFI above 3/11, the complications of Urinary tract infections, wound healing issues and reoperations increased (P < .05). Frail patients are at a higher risk of complications like urinary tract infections, wound complications and reoperations and show worse functional outcomes. Conclusion: Modified Frailty index can be used as a predictor of complications and would be highly useful in preoperative counseling for patients undergoing lumbar fusion. Frail patients are at a higher risk of complications, show worse functional outcomes and should be carefully monitored during their hospital stay to prevent reoperations.

415

P519: Postoperative Adverse Events Secondary to Iatrogenic Vascular Injury During Anterior Lumbar Spinal Surgery

Olivier Groot ^1,2 , Dennis Hundersmarck ¹ , Amanda Lans ¹ , Michiel Bongers ¹ , Aditya Karhade ¹ , Yue Zhang ¹ , Floris van Tol ² , Jorrit-Jan Verlaan ² , Jahan Mohebali ³ , and Joseph Schwab ¹

¹ Massachusetts General Hospital, Orthopaedics, Boston, USA

² University Medical Center Utrecht, Orthopaedics, utrecht, The Netherlands

³ Massachusetts General Hospital, Vascular Surgery, Boston, USA

Introduction: Anterior lumbar spine surgery (ALSS) requires mobilization of the great vessels, resulting in a high risk of iatrogenic vascular injury (VI). It remains unclear whether VI is associated with increased risk of postoperative complications and other related adverse outcomes. The purpose of this study was to (1) assess the incidence of postoperative complications attributable to VI during ALSS, and (2) outcomes secondary to VI such as procedural blood loss, transfusion of blood products, length of stay (LOS), and in hospital mortality. Materials and Methods: This is a retrospective propensity-score matched, case-control study at two academic and three community medical centers. Patients 18 years of age or older, undergoing anterior lumbar spine surgery at two academic tertiary care and three community medical centers between January 1st, 2000 to July 31st, 2019 were included in this analysis. The primary outcome was the incidence of postoperative complications attributable to VI, such as venous thromboembolism (VTE), compartment syndrome, transfusion reaction, limb ischemia, and reoperations. The secondary outcomes included estimated operative blood loss (milliliter), transfused blood products, LOS (days), and in-hospital mortality. In total, 1035 patients were identified, of which 75 (7.2%) had. For comparative analyses, the 75 VI patients were paired with 75 comparable non-VI patients by propensity-score matching. The adequacy of the matching was assessed by testing the standardized mean differences (SMD) between VI and non-VI group (>.25 SMD). Results: Two patients (2.7%) had VI-related postoperative complications in the studied period, which consisted of two DVTs occurring on day three and seven postoperatively. Both DVTs were located in the distal left common iliac vein (CIV). The VI these patients suffered were to the distal inferior caval vein and the left CIV respectively. Both patients did not develop additional complications in consequence of their DVTs, however, did require systemic anticoagulation and placement of an inferior cava vein filter. There was no statistical difference with the non-VI group where no instances (0%) of postoperative complications were reported (P =.157). No differences were found in LOS or in hospital mortality between the two groups (P = .157 and P = .999, respectively). Intraoperative blood loss and blood transfusion were both found to be higher in the VI group in comparison to the non-VI group (650 ml, interquartile range [IQR] 300-1400 vs 150 ml, IQR 50-425, P =< .001; 0 units, IQR 0-3 vs 0 units, IQR 0-1, P = .012, respectively). Conclusion: This study found a low number of serious postoperative complications related to VI in ALSS. In addition, these complications were not significantly different between the VI and matched non-VI ALSS cohort. Although not significant, the found DVT incidence of 2.7% after VI in ALSS warrants vigilance and preventive measures during the postoperative course of these patients.

524

P520: Preoperative Diagnosis of a Mental Health Disorder Is Associated With Increased Postoperative Rates of Dysphagia After Anterior Cervical Spine Surgery

Athan Zavras ¹ , Ali Piracha ¹ , Zakariah Siyaji ¹ , Talha Qadri ¹ , Arash Sayari ¹ , Nicholas Shepard ¹ , Sahil Sood ¹ , Nour Saleh ¹ , Mohammed Kazi ¹ , and Matthew Colman ¹

¹ Rush University Medical Center, Orthopedic Surgery, Chicago, USA

Introduction: Mental health disorders (MHDs) have been implicated with worse postoperative outcomes after various surgical procedures including higher rates of surgical site infection, postoperative pain, opioid usage, and revision procedures. Past studies have also demonstrated a higher prevalence of dysphagia in both acute and community mental health settings. Dysphagia is among the most common complications after anterior cervical spine surgery (ACSS) including anterior cervical discectomy and fusion (ACDF), total disc replacement (TDR), and corpectomy as a result of manipulation of the soft tissue and neurovascular structures of the anterior neck. Currently, there is sparse literature describing the association between an established diagnosis of a MHD and the rate of dysphagia after ACSS. Materials and Methods: We retrospectively evaluated all patients who underwent ACSS with a single surgeon between the years of 2014 and 2020. Patients with a minimum follow-up of 6 months were stratified into two cohorts: the first consisting of patients without an established diagnosis of an MHD (Non-MHD), and the second including patients with a diagnosed MHD and history of pharmacotherapy. Patients with diagnoses of depression, anxiety, bipolar disorder, schizophrenia, post-traumatic stress disorder (PTSD), and substance abuse disorder were included in the MHD cohort. Outcomes were measured using pre- and postoperative patient-reported outcome (PROs) scores which included the SWAL-QOL survey for dysphagia, Neck Disability Index (NDI), Visual Analog Scale (VAS) Arm, VAS neck, Short Form 12-Item Health Survey (SF12), Veteran’s Rand 12-Item Health Survey (VR12), and Patient-Reported Outcomes Measurement Information System (PROMIS) depression scores. T-test and chi-square was performed for continuous and categorical variables. The threshold for statistical significance was set toP< .05.Results:A total of 68 (34 female, 34 male) and 123 (54 female, 69 male) patients with and without a diagnosis of a MHD were assessed with mean follow-up of 8.91 ± 8.47 and 9.45 ± 8.07 months (P= .67), respectively. There were no significant differences in baseline demographics or preoperative general health, swallow function, and disease specific PROs. The MHD group reported significantly worse baseline PROMIS depression (MHD: 56.1 ± 8.56, Non-MHD: 48.2 ± 9.84,P< .001), SF12 (MHD: 43.5 ± 11.0, Non-MHD: 50.5 ± 10.7,P< .001), and VR12 (MHD: 45.9 ± 10.8, Non-MHD: 52.1 ± 11.1,P= .001) mental health components compared to Non-MHD patients. This group continued to have worse mental health status postoperatively, as reported by PROMIS depression (MHD: 52.4 ± 11.3, Non-MHD 47.0 ± 10.0,P= .024), SF12 (MHD 47.0 ± 8.49, Non-MHD: 49.7 ± 7.16,P= .019) and VR12 (MHD: 49.7 ± 8.40, Non-MHD: 52.3 ± 7.52,P= .027). Postoperative assessment of SWAL-QOL also showed worse dysphagia outcomes in the MHD cohort (80.1 ± 12.2) than Non-MHD patients (86.0 ± 12.1,P< .001). All other postoperative assessments observed no differences.Conclusion:ACSS is associated with significantly higher postoperative dysphagia in patients diagnosed with an MHD when compared to patients without an established diagnosis, although the absolute difference was small. Other than mental health measures, there were no differences in postoperative physical health outcomes between patients in the mental health population and their counterparts without a psychiatric diagnosis. Given the high prevalence of MHDs in patients with spinal pathology, it is important for spine surgeons to take note of the increased incidence of dysphagia faced by this patient population.

538

P521: Dyspnea and Pulmonary Thromboembolism, as Presentation of Aortic Injury Due to Pedicle Screws: Case Report and Literature Review

Fernando Alvarado Gómez ¹ , Luis Carlos Morales Saenz ¹ , Yesid Araque ¹ , Santiago Rosales ¹ , and Gina Velásquez Solano ¹

¹Hospital Universitario Fundación Santa Fe de Bogotá, Bogotá, Colombia

Introduction: Aortic injuries in spinal surgery are rare but life-threatening complications. This article will expose our experience in the repair of aortic injury as a complication of the use of pedicle screws in spinal surgery. Material and Methods: The first case is of a 30-year-old woman whose initial procedure was correction of scoliosis with T3-L4 transpedicular arthrodesis in an external institution; the patient had initial management due to the presence of collection at the lumbar level. Upon admission to our institution, the management of infection and collection described above continued, and she subsequently presented pulmonary thromboembolism, and images found an incidental finding of aortic injury by pedicle screw and confirmed the diagnosis with intravascular ultrasound. Management was performed with a stent and screw removal associated with the lesion. The second case consists of a 37-year-old male patient who presented multiple vertebral fractures which required subsequent stabilization management in an external institution. He entered our institution due to respiratory symptoms due to dyspnea. Within the extension studies, a pedicle screw was found in contact with the aorta without any other finding associated with the initial symptoms. This diagnosis was confirmed by means of intravascular ultrasound and the same management of the first case was performed. Results: In each case, adequate removal and repositioning of the pedicle screws associated with the lesion was achieved. The stent placement did not present complications and the patients had a satisfactory postoperative follow-up. Conclusions: This type of injury can produce a high risk of morbidity and mortality and patients may present different symptoms. Management of these lesions is usually endovascular, and screw removal or relocation is desired. In our experience with these cases, the use of intravascular ultrasound is especially useful for diagnostic confirmation.

641

P522: Modic Changes and Higher Total End Plate Damage Score Are Independent Risk Factors for Developing Surgical Site Infection

Dilip Chand Raja Soundararajan ¹ , Anupam Inamdar Pradip ¹ , Shanmuganathan Rajasekaran ¹ , Ajoy P Shetty ¹ , and Rishi Kanna ¹

¹ Ganga Medical Centre and Hospitals Pvt Ltd, Spine Surgery, Coimbatore, India

Introduction: The etiology of Modic changes in lumbar spine has been a matter of controversy with recent studies establishing an association between Modic changes and the presence of a sub-acute infection in the vicinity of end-plates using various methods such as culture, serological tests like ELISA and newer methods of detection of bacteria like 16 S rRNA sequencing. However, certain studies have also denied this association by failing to demonstrate the presence of bacteria in disc tissue. There are limited studies in literature investigating Modic changes as a cause of postoperative surgical site infections (SSI). Material and Methods: We retrospectively analysed the data of 1124 patients for the presence of SSI and Modic changes in pre-operative MRI scans within a time frame of 3 years (2016 to 2019) to investigate an association between Modic changes and SSI. Student’s t- test and Fisher’s exact test was used for analysis of variables and P values of <.05 were considered statistically significant. Results: Modic changes were present in 670 (59.6%) of individuals who underwent surgery with Type 2 being the most common type (82.68%), followed by Type 1 (7.01%), Mixed (6.11%) and lastly Type 3 (4.17%). The prevalence of SSI was 4% (44/1124 patients). Age and sex were not associated with SSI. Modic positivity among those who had SSI was high-79.54% (35/44) when compared to prevalence of 58.79% (635/1080) among controls. This association between the prevalence of Modic changes in pre-operative MRI scans and incidence of SSI was significant (P value-.006). However the type or location of Modic change had no correlation with incidence of SSI. Modic positivity had an association with deeper SSI (P = .023). Presence of a higher Total end-plate damage score was also found to be associated with SSI (P value-.008). In patients without Modic changes, the presence of end-plate depressions (4/62) when compared to those who didn’t have depressions (5/392) had a significant association with SSI. Among the types of surgery Discectomy had a higher association with SSI (P value = .003) when compared to fusion (P value = .071). Cultures were positive only in 25% of patients with SSI, the most common bacteria isolated being Pseudomonas aeruginosa and Klebsiella. Conclusion: Our data suggests that the presence of preoperative Modic changes and an end-plate damage score > 6 are independent risk factors for developing surgical site infections. Modic changes could be foci of sub-acute infection and not mere markers of degeneration, as originally described. Further since culture yield is only 25% in these infections, molecular diagnostics might be the need of the hour to isolate these fastidious organisms.

645

P523: Bezold-Jarisch Reflex Causing Bradycardia and Asystole in a Case of Severe Dystrophic Cervical Kyphotic Deformity - A Case Report and Review of Literature

Dilip Chand Raja Soundararajan ¹ , Shanmuganathan Rajasekaran ¹ , Sri Vijay Anand KS ¹ , Ajoy P Shetty ¹ , and Rishi Kanna ¹

¹ Ganga Medical Centre and Hospitals Pvt Ltd, Spine Surgery, Coimbatore, India

Introduction: Neurofibromatosis (NF) is associated with severe acute and rigid dystrophic deformities of spine and progress rapidly over a short span of time. A 17-year-old adolescent with NF presented with progressive deformity of neck and upper back, for ten years with recent onset clumsiness of hands, loss of dexterity, gait instability and difficulty in performing day to day activities over past six months. Plain radiographic image revealed a severe dystrophic cervical kyphotic deformity of 126° and CT showed C5-C6 and C6-C7 facet joint subluxation with buckling collapse of cervical spine. MRI demonstrated stretching of the spinal cord with thinned out caliber over the acutely deformed cervical spine. A single stage 540-degree approach comprising anterior release (corpectomy), posterior column shortening, and instrumentation and finally anterior reconstruction was planned. The aim is to describe a case of severe kyphotic deformity of cervical spine with narrow thoracic inlet causing bradycardia and asystole, only during prone positioning and its successful management. Materials and Methods: Pre-operative ambulant Halo Gravity traction (HGT) reduced the deformity to 90° with a 36° curve correction. After C5, C6 and C7 corpectomy, during prone positioning, a sudden onset bradycardia was followed by asystole, which disappeared immediately on turning over to supine position. With no detectable scientific reasons behind this phenomenon, surgery was called off after 2 additional failed attempts of prone positioning. Results: A retrospective analysis of CT and MRI showed severe narrowing of thoracic inlet. Bezold-Jarisch reflex is a cardio-inhibitory reflex occurring due to vagal stimulation and results in sudden bradycardia, asystole and hypotension. In this patient, the right thoracic inlet was severely narrow and prone positioning caused a further dynamic compromise stimulating right vagal nerve. Right vagus supplies the Sinoatrial node which is the natural pacemaker of heart and vagal stimulation causes sympathetic inhibition. After a multidisciplinary team meeting involving anesthetists, otolaryngologists, spine surgeons and cardiothoracic surgeons, it was decided to attempt surgical decompression of thoracic inlet. The medial end of the clavicle along with limited manubrium excision relieved the vagal compression and allowed prone positioning. C2-T4 instrumented decompression followed by anterior reconstruction and cervical plating were performed. Post-operative period was uneventful, and the final Cobbs angle was only 45°. Conclusion: Bezold-Jarisch Reflex as a result of narrow thoracic inlet caused by rigid cervical kyphosis and compensatory hyper lordosis of upper thoracic spine has never been reported. Preoperative recognition of narrow thoracic inlet might help surgeons to foresee this rare entity. Thoracic inlet decompression is an efficient way of addressing this unique complication.

744

P524: Delayed Postoperative Spinal Dural Liquorrhea: Treatment, Prevention and Control After Surgery of Degenerative Lumbar Stenosis

Alexander Peyker¹, Dmitry Dzukaev¹, Mikhail Safronov¹, and Ivan Khutornoy²

¹ 1City Clinical Hospital 67 n.a. L.A.Vorokhobov, Moscow Spine Center, Moscow, Russian Federation

² 3High school of medicine Lomosov University, Moscow, Russian Federation

Introduction: Delayed postoperative spinal dural liquorrhea - liquorrhea, which appears in the period of 10-30 days after intervention, manifesting as accumulation of liquor in the soft tissues after wound healing with the formation of the "liquor pillow” without any signs of liquorrhea during the operation. These type of liquorrhea is iatrogenically indirect. Moreover, during the operation, there are no signs of dura damaging and consequently liquorrhea. A direct injury of the dura during the operation is possible, as well as indirect damage of the dura (damage with the uneven contour of the bone “working window” during changing location of the dural sac with the microsurgical protector). The objection was developing of the treatment protocol of delayed postoperative spinal dural liquorrhea and methods for its prevention. Material and Methods: In this retrospective single group study, we analyzed results of the operative treatment of patients with degenerative spinal stenosis of the lumbosacral, which had clinical and local manifestations of liquorrhea appeared in first 10-30 days after operation, proven with MRI. Attempts to conservative treatment: the placing of lumbar drainage, prescription drugs that reduce liquor production, gave a partial and incomplete effect. In all cases revision of postoperative wound together with duraplasty was performed. Duraplasty was carried out using synthetic plastic materials with the obligatory addition of a fat flap, which was fixed in the zone of operation defect with sutures and medical glue. In all patients lumbar drainage was placed intraoperatively. The wound was sutured with suture material with a resorption period of at least 45 days. Results: All patients achieved a positive effect from surgery. The best option for surgical treatment we considered a revision of the postoperative wound together with duraplasty with a fat flap fixated with medical glue and subsequent lumbar drainage until the postoperative wound is completely healed and there is no data on relapse of liquorrhea on MRI control. Conclusion: In our opinion, delayed liquorrhea is an iatrogenically mediated phenomenon, the cause of which is the incorrect formation of the bone "working window" with forming of sharp bony protuberance that traumatize thinned dura as a result of changes in liquorodynamics during patient activation in the postoperative period. The delicate formation of the bone “working window”, careful work with the dural sac, accurate suturing of the wound with suture material with a long period of resorption minimizes the risks of this life-threatening complication, which is delayed postoperative spinal dural liquorrhea.

953

P525: Clinical Pilot Study Showing the Safety and Efficacy of Intramuscular Injection of Atelocollagen for Prevention of Paraspinal Muscle Atrophy After Spine Surgery

Jungwoo Hur ¹ , Jae-Taek Hong ¹ , and Sang-Hyo Lee ¹

¹ Eunpyeong St. Mary's Hospital, The Catholic University of Korea, Neurosurgery, Seoul, South Korea

Introduction: Atelcollagen has been widely used as an intradermal filler to restore soft tissue defect. Many studies demonstrated that atelocollagen provides good therapeutic results by promoting cell proliferation and enhances the healing effect on injured connective tissues such as tendons and fasciae, while causing few complications. This clinical study was designed to assess the safety and efficacy of intramuscular injection of atelocollagen for prevention of paraspinal muscle atrophy after spine surgery. Material and Methods: 118 patients who underwent single level posterior lumbar interbody fusion (PILF) between December 2017 and April 2019 were retrospectively reviewed. In the study group of 58 patients, 3mL of gel type 3% atelocollagen solution was prepared and injected into the multifidus muscle after wound closure. Clinical efficacy was evaluated by improvement of back pain, elevation of muscle enzyme and inflammatory markers. Radiologic efficacy was evaluated with comparison of paraspinal muscle cross-sectional area (CSA) in MRI. The safety was assessed with vital sign monitoring and a survey on all adverse events over 12 weeks. Results: Significant improvement of back pain was observed in all patients after the surgery. VAS for back pain was significantly lower in the study group after 1 month postoperatively. Serum level of muscle enzyme and inflammatory markers were significantly lower in the study group. Reduction of postoperative multifidus CSA was significantly lower in the study group. No major procedure related complications were observed during the follow-up period. Conclusion: Intramuscular injection of atelocollagen is safe and feasible for prevention of paraspinal muscle atrophy after spine surgery. This novel method seems advantageous for accelerating wound healing without causing inflammation. Randomized controlled trials with lager data sample is needed to confirm the results.

1153

P526: Teripaeratide as a Rescue Option in Implant related Complications in Osteoporotic Spine Patients Preventing Revision Spine Surgeries

Munjal Shah ¹ , Kunal Shah ¹ , Priyank Patel ¹ , Abhay Nene ¹ , Harshal Bamb ¹ , and Hriday Acharya ¹

¹Lilavati Hospital and Research Centre, Orthopaedic spine, Mumbai, India

Introduction: Osteoporosis is very common progressive skeletal disease in elderly population. Instrumented Spine surgeries are very frequently performed in elderly individuals. Osteoporosis is significant risk factor for revision spine surgeries. Screw Loosening, Proximal junctional kyphosis, cage subsidence, screw pullout, Implant breakage are the complications seen in operated Osteoporotic spine patients for various ailments.13.5 percent of conservatively treated Osteoporotic spine fracture patients suffer from non-union. Most of these patients will require surgical intervention. Various studies have shown decrease in implant related complications and improvement in fusion rates in osteoporotic patients following use of Injection teriperatide. Use of Injection teriperatide following impending implant failure in Osteoporotic Spine or Non Union OVCF without focal neurology is not Known. In this case series we have used Injection Teriperatide in various gametes of previously operated Osteoporotic patients to bailout from revision or primary spine surgery. Material and Methods: 11 patients (range 65-80 years) patients presented to us with instability type of back pain between January to March 2017. On investigation patients had cage subsidence and migration with inferior end plate vertebral fracture, end plate erosion, Nonunion of osteoporotic vertebral compression fracture, screw loosening, screw breakage, Proximal junctional kyphosis, Post vertebroplasty intravertebral instability. All patients were osteoporotic and were not on any anti osteoporotic treatment. All patients had no focal neurology. All patients were reluctant to undergo surgery. After ruling out all contra-indications, daily subcutaneous injection teriperatide was started in all of them for 12-24 months. All were followed up initially at 3 months for first year and then 6 monthly. All patients were advised to avoid higher impact activities during their treatment. None, except one, had any complications during their treatment and till last follow-up. One patient required reintervention. Results: VAS and MODI scores significantly improved at 3 months and remained to be so at end of treatment. Osteoporotic fracture non-union healed at end of treatment. None of the patient developed neurological deficit during treatment. No changes were noticed in Implant position, except in one case, at the end of treatment which heralded us to intervene surgically. Conclusion: Osteoanabolic Teriperatide injections should be considered as one of the treatment in osteoporotic non-union fractures and operated elderly with impending implant failure as a bailout therapy or at least to delay intervention in neurologically intact patients.

1277

P527: Is There a Difference in Screw Accuracy, Robot Reliability, and Radiation Exposure Between the MAZOR X and the Renaissance? A Propensity-Matched Analysis of 1179 Robot-Assisted Screws

Nathan Lee ¹ , Ian Buchanan ¹ , Venkat Boddapati ¹ , Justin Mathew ¹ , Eric Leung ¹ , Joseph Lombardi ¹ , and Ronald A. Lehman ¹

¹ The Och Spine Hospital at New York-Presbyterian, New York, USA

Study Design: Single Center Cohort Analysis. Objective: To compare the screw accuracy, operative efficacy, and radiation exposure of two robotic systems for spine surgery. Summary of Background Data: It is important to investigate if recent advances in robotic technology have any clinical significance. There is no current literature comparing the screw accuracy, robot operative efficacy, and radiation exposure between the Mazor X and Renaissance robot systems. A single center investigation enables a detailed exploration of robot complications and radiation exposure that may be difficult for larger databases or multicenter studies. Methods: Adult (≥18 years old) patients who underwent robot-assisted spine surgery from 2016 to 2019 were reviewed. A propensity score matching algorithm was used to match Mazor X cases to Renaissance cases to control for potential selection bias. All cases involved a preoperative C-arm for planning and an intraoperative O-arm(Medtronic PLC, Medtronic Inc, Dublin

Ireland) for screw evaluation. Outcomes of interest included operative efficacy (robot time per screw), radiation exposure (preoperative and intraoperative), and robot complications (screw breach as measured according to the Gertzbein and Robbins classification and robot abandonment). Screw accuracy was measured using Vitrea Core software by two independent orthopedic surgeons. Bivariate comparisons were performed using chi-square and t-tests. A P-value <.05 was considered statistically significant. Results: After propensity score matching, a total of 65 patients (Renaissance: 22 vs X: 43) were included. Patient demographics, diagnoses, discharge disposition, and operative factors (e.g. number of instrumented levels, pelvic fixation, interbody fusion, planned robot screws per patient) were similar between robot systems (P > .05). Radiation exposure (dose and time), including preoperative and intraoperative levels were not different between robot systems. The X appeared to have a shorter robot time per screw but this was not statistically significant (Renaissance: 4.6 minutes vs X: 3.9 minutes, P = .246). The X robot was significantly more reliable with a robot abandonment rate of only 2.3% (vs Renaissance: 22.7%, P = .007). The pedicle screw accuracy was similar between robots (Screw exchange for breach rate: Renaissance: 1.1%% vs X: 1.3%, P = .786); however, the S2AI screw breach rate was significantly lower for the X (Renaissance: 9.5% vs X: 1.2%, P = .025). Other complications including dural tear, loss of motor/sensory function, estimated blood loss, and blood transfusion were similar between robot systems. Conclusion: This is the first comparative analyses of robot complications, radiation exposure, operative efficacy between the Mazor X and Renaissance systems. There are substantial improvements in the X robot, particularly in the perioperative planning processes, which likely contribute to the X’s superiority in screw accuracy and robot reliability.

1362

P528: Preoperative Opioids Before Adult Spinal Deformity Surgery Associated With Increased Reoperations and High Rates of Chronic Opioid Use at 3 Year Follow Up

Andre Samuel ¹ , Catherine Himo Gang ¹ , and Sheeraz Qureshi ¹

¹ hospital for special surgery, New York, USA

Introduction: With the current opioid crisis, patients undergoing surgery for ASD are at particular risk for opioid related complications due to significant preoperative disability and surgical morbidity. No previous studies consider preoperative opioids in this population. Methods: Patients undergoing posterior spinal fusion (7 or more levels) for ASD were identified. All patients had at least 3 years of postoperative follow up. 3 years postoperatively. Prescriptions for 4 different opioid medications (hydromorphone, oxycodone, hydrocodone, and tramadol) were identified within 3 months preoperatively and up to 3 years postoperatively. Multivariate regression was utilized to determine the association of preoperative use with reoperations and with postoperative opioid use, controlling for both patient and surgery-related confounding factors. Results: A total of 743 patients were identified and 59.6% (443) had opioid prescriptions within 3 months preoperatively. Postoperative opioid prescriptions were identified in 66.9% of patients at 12 months postoperatively, and in 54.8% at 36 months postoperatively. The 3-year reoperation rate was 11.0% in patients without preoperative prescriptions, 16.0% in patients with preoperative any opioid prescriptions (P = .07), and 34.8% in patients with preoperative hydromorphone prescriptions (P < .01). In multivariate analysis, preoperative opioid prescriptions were associated with increased reoperations (odds ratio [OR]: 1.62, P = .04), and chronic postoperative opioid use (OR: 4.40, P < .01). Preoperative hydromorphone prescriptions had the strongest association with both reoperations (OR: 4.96; P < .01) and chronic use (OR: 5.19: P = .03). Conclusion: In the ASD population preoperative opioids are associated with both reoperations and chronic opioid use, with hydromorphone having the strongest association. Further investigation of the benefits of preoperative weaning programs is warranted.

1377

P529: Delayed Vertebral Artery Rupture Following Anterior Cervical Discectomy and Fusion

Bharath Raju ¹

¹Kempegowda Institute of Medical Science, Neurosurgery, Bengaluru, India

Introduction: Vertebral artery injury is encountered in .07% of cases following cervical spine surgery. Only 9% of those are attributed to Anterior Cervical Discectomy. Delayed rupture of the vertebral artery and superior thyroid artery pseudoaneurysm following intraoperative injury has been described. Here we are presenting a unique case of spontaneous, life-threatening delayed rupture of the vertebral artery following uncomplicated anterior cervical discectomy and fusion and its management in a low resource setting. Method: Case report: An adult male patient with cervical C5-6 large, extruded disc presented with left upper limb radicular pain and shoulder abduction weakness. He underwent anterior cervical discectomy and fusion with iliac graft, plates, and screws fixation. Patient was positioned supine with head on horseshoe support without posterior neck support and cervical traction. Procedure was uneventful and was discharged on day 4. On day 7, upon straining, he noticed profuse bleeding from the wound and developed respiratory distress. Wound was explored, bleeding controlled, and tracheotomized immediately by a local surgeon and referred back with new right shoulder weakness suggesting iatrogenic brachial plexus injury. CT angiogram showed discontinuation of right vertebral artery at the C5 and C6 levels with narrowed VA both above and below. Results: Patient was managed conservatively and recovered with persistent shoulder weakness. Probable source of bleeding is right vertebral artery. Possibility of pseudo aneurysm rupture was considered. Indirect injury to VA due to excessive mobility of adjacent vertebral bodies during graft impaction, resulting in pseudoaneurysm formation, was speculated. As level of narrowing of vertebral artery and roots of upper trunk correlated, possibility of inadvertent coagulation during hemostasis was considered. Conclusions: Avoid larger graft and forceful impaction. Apply cervical traction in all, especially if amount of extruded disc is large, to prevent excessive mobility of spine and indirect injury to vertebral artery. Endovascular intervention is the procedure of choice and would have prevented inadvertent brachial plexus injury.

1476

P530: Trends of Survival of Metastatic Spine Disease: A Retrospective Chart Review

Firas Alsebayel ¹ , Adnan Alkandari ² , Abdullah Eissa ² , Muath Almajed ¹ , Nawaf Alogayyel ² , Ali Alhandi ² , and Faisal Konbaz ²

¹ King Saud bin Abdulaziz University for Health Sciences, College of Medicine, Riyadh, Saudi Arabia

² National Guard Health Affairs, Department of Orthopedic Surgery, Riyadh, Saudi Arabia

Introduction: Metastasis is considered one of the most common causes of cancer-related deaths worldwide. The skeletal system is the third most common site of metastasis after lungs and liver with the spine being the most commonly affected site. Despite the great advances in medical therapy, surgery remains the mainstay of treatment for spine metastasis. However, several studies have investigated the surgical outcome of the metastatic spine and found to have a discordance in their results. This research aims to study the rate of mortality and morbidity of surgical intervention to the metastatic spine disease in Riyadh, Saudi Arabia. Material and Methods: A retrospective chart review that looked into patients who underwent surgical intervention for metastatic spine disease in a tertiary-care hospital between the period of 2016 to 2020. The primary outcomes included intraoperative and postoperative complication, thirty-day mortality, ninety-day mortality, and one-year survival rates. Secondary outcomes included the need for readmission, reoperation, postoperative neurological improvement, and 30-day ER visits. Results: A total of 49 patients underwent surgical intervention during the period of 2016 to 2020. Breast was the most common primary lesion for metastasis, followed by lung and multiple myeloma. Postoperative surgical complications occurred to 34% of the sample. 18% of patients reported marked improvement following surgery. The 30-day and 90-day mortality rates were found to be 3% and 13%, respectively. The overall 1-year survival rate was 66%. Conclusion: In conclusion, our study showed that despite the great risk and complexity of surgical interventions to the metastatic spine, surgery provided an acceptable rate of morbidity and mortality.

1703

P531: Esophageal Diverticulum: A Rare and Delayed Complication of Anterior Osteosynthesis of the Cervical Spine

Mohamed Ben Jemaa ¹ , Mohamed Ghorbel ¹ , Achraf Lajmi ¹ , Khaled Keskes ¹ , Hedi Chaabouni ¹ , Ameur Abid ¹ , Mourad Aoui ¹ , Wassim Zribi ¹ , and Hassib Keskes ¹

¹ Habib Bourguiba University Hospital of Sfax, Tunisia, Orthopedic Surgery and traumatology Department, Sfax, Tunisia

Introduction: Acquired esophageal diverticula are rare and delayed complications after anterior cervical spine osteosynthesis. They can be life-threatening in the event of an associated esophageal perforation. Through our observation, we try to study the etiopathogenic particularities, clinical aspects and therapeutic modalities of the esophageal diverticulum complicating the anterior osteosynthesis of the cervical spine. Material and Methods: A 35-year-old patient, who was a victim of a domestic accident, suffered from a cervical spine fracture complicated by quadriplegia. He was treated with anterior osteosynthesis. Nine months later, the patient developed solid food dysphagia. Clinical examination showed salivary stasis in the hypopharynx. The esophageal transit showed an image of saccular addition connected to the posterior wall of the esophagus by a broad neck and located in front of the osteosynthesis material. This aspect, compatible with an esophageal diverticulum was best analyzed by cervical CT scan showing a pre-vertebral and retro-tracheal collection of heterogeneous hydro-aeric content. The patient underwent a diverticulectomy via the left latero-cervical approach associated to ablation of the osteosynthesis material. A nasogastric tube was placed and removed after esophageal cicatrisation. Results: The outcome was simple. At the last check-up, the radiological control radiological showed no esophageal leakage or fistula. Conclusion: Esophageal diverticulum is a rare complication of anterior internal fixation of the cervical spine. It must be evoked in case of any solid food dysphagia of late postoperative onset. Its treatment is surgical. It consists in excision of the diverticulum associated with ablation of the osteosynthesis material to stop the inflammatory process.

1737

P532: Recent Complications in Spinal Surgery Performed by American Board of Orthopaedic Surgery (ABOS) Part II Candidates (2008-2017)

Caleb Yeung ¹ , Andrew Schoenfeld ¹ , Harry Lightsey IV ¹ , James Kang ¹ , and Melvin Makhni ¹

¹ Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA

Introduction: Recent research has demonstrated the importance of surgical experience and clinical volume in minimizing complications after spine surgery. This may be challenging for orthopaedic spine surgeons who are just starting their practice. We sought to evaluate complications following spine surgery using American Board of Orthopaedic Surgeons (ABOS) Part II examination data from 2008-2017. Material and Methods: We performed a retrospective review of surgical cases submitted to the ABOS by candidates with a self-designated subspecialty of spine surgery who took the Part II Oral Examination between 2008-2017. Complications, including peri-operative mortality as reported by candidates to the ABOS, were tracked over time. Complications were classified as surgical or medical using a pre-defined algorithm. Multivariable Poisson regression analyses adjusting for confounders were used to assess rates of complications and mortality over time. All analyses controlled for biologic sex, age, surgical diagnosis and surgical location. Results: A total of 37,539 spine surgical patients were analyzed, with an average of 3,754 cases performed each year. Following adjusted Poisson analysis, we determined that cases in 2017 had an increased likelihood of complications when compared to those treated in 2008 (IRR 1.20; 95% CI 1.09, 1.32). Similar findings were encountered for surgical complications (IRR 1.20; 95% CI 1.07, 1.34). In contrast, spine surgical cases reported to the ABOS in 2017 had a 55% lower likelihood of mortality when compared to procedures performed in 2008 (IRR .45; 95% CI .24, .84; P = .01). Conclusion: Our analysis of ABOS Part II candidates demonstrates that reported complication rates may be increasing while mortality is decreasing. The etiologies behind these findings are likely multifactorial. Encouragingly, we believe that observed reductions in mortality suggest overall improvements in patient safety following spine surgery. At a minimum, our data provide benchmarks through which spine surgeons, hospitals and residency or fellowship programs can evaluate performance.

1791

P533: Emergency Spinal surgery in Octo- and Nonagenarians: A Single Centre Retrospective Observational Study of Peri- and Post-Operative Complications

Sam Hopwood ¹ , Daniel Watts ² , Ashok Ramasamey ¹ , Catherine Chinnery ³ , and girish swamy ¹

¹ Norfolk and Norwich University Hospital, Trauma & Orthopaedics, Norwich, United Kingdom

² Norfolk and Norwich University Hospital, Norwich, United Kingdom

³ UEA Medical School, NR4 7TJ, United Kingdom

Introduction: Growing numbers of elderly patients have seen an increase in demand and exposure to spinal surgery. Whilst complications have been described and reported for elective surgery, emergency spinal surgery in the over 80s has not. This study looks to report on perioperative and post-operative complications in octo- and nonagenarians. Material and Methods: This single Centre retrospective observational study looked back sequentially at previous emergency spinal operations in the over 80s age range. Patients were identified through an in hospital orthopaedic database (Bluespier^©) with data being gathered from this and patient discharge letters (ICE Desktop ©). Major peri- and post-operative complications were recorded with a major complication being defined as a life-threatening or permanently damaging event. Results: 51 operations in 48 patients were identified over a period of 8 years (2012-2020). Peri-operative complications occurred in 6.25% of patients (3/48) with 1 dural tear, 1 pharyngeal perforation and 1 cardiac arrythmia. Post-operative complications occurred in 47.9% of patients (23/48) with the most frequent complication being bronchopneumonia in 8 of the 48 patients (16.6%). Further frequent complications included swallowing difficulties (12.5%), urinary tract infections or urosepsis (10.4%) and acute kidney injury (8.3%). 7 deaths were recorded in total (14.6%) with 4 of these attributed to cervical spine fractures (±dislocation). There were 23 procedures in the cervical spine compared with 19 in the lumbar spine, 8 in the thoracic spine and 1 multi-level operation. The most frequent individual procedure was an anterior cervical discectomy and fusion (23.5%) followed by a lumbar discectomy/decompression (21.6%). Conclusion: Although recent studies have argued that elective spinal surgery in elderly patients has a relatively safe profile, our study suggests that emergency surgery should be continued to be regarded with caution. Our study is the first to provide a reported prognostic outlook for patients in an emergency setting. This is important for surgeons, patients and families in discussions regarding management. It also provides surgeons and clinicians with the awareness of more frequent post-operative complications in this patient demographic.

1800

P534: Long Term Follow Up of Intra Op Incidental Durotomy Managed With or Without Suturing

Alok Jain ¹ , Tejasvi Agarwal ² , and Gajendra Pawal ²

¹ The Spine foundation, Spine Surgery, Mumbai, India

Introduction: Incidental durotomy is a relatively common occurrence during spinal surgery. Although it is generally accepted that incidental durotomies (ID) should be primarily repaired but there is still a lack of consensus for the treatment of ID. This study is Retrospective analysis of prospectively collected data of patients who underwent spinal surgery at a single institution for a period of 10 years. Aim: To establish that incidental durotomy treated without primary suturing does not affect the long term functional outcome following spine surgery as compared to those primarily sutured. Material and Methods: A retrospective review of prospectively collected data was conducted in which the outcome databases, clinical and surgical records of consecutive patients who underwent spinal surgery performed by the senior surgeons from January 2010 to December 2019 were considered. Patient with intra op identified incidental durotomy were divided in 2 groups depending on the dural closure technique used: Group A: sole dural suture; Group B, patch only without suture (collagen matrix patch and/or muscle and/or fat). Functional outcomes for these two groups were compared at variable intervals ranging from 6 months being least to 9 years being the maximum followup. Functional outcome used for our study were the Modified Oswestry Disability Index (mODI) and Visual Analogue Scores for leg pain (VAS-L) and back pain (VAS-B). Results: A total of 2621 consecutive patients were reviewed. 174 patients were found to have Incidental durotomy occurring at the time of surgery (6.6% overall incidence). Incidence varied according to the specific procedure performed but was highest in the group of revision surgery. There were 93 males and 81 females, with an average age of 54.8 years. Post operatively at 6-month follow-up, though both groups should improvement functionally but there was marginal better functional outcome in Group A patient but at last long term follow-up, patients of both the groups showed similar improvement in functional scores with no significant differences (P > .05). Conclusion: Our study demonstrates that incidental durotomy in spine surgery can be successfully managed without primary suture repair with no negative long term effect on functional outcome.

1809

P535: Mechanical Complications Following L2-S1 Anterior and Posterior Spinal Fusion Without Iliac Fixation

Chadi Tannoury ¹ , Rahul Bhale ² , Qasim Ajmi ¹ , Aziz Saade ¹ , and Tony Tannoury ¹

¹ Boston Medical Center, Orthopedic Surgery, Boston, USA

² Boston University School of Medicine, Boston, USA

Introduction: The use of additional iliac fixation in the setting of L2-S1 fusion for degenerative spinal pathology has long been debated. Some studies have advocated for the use of iliac fixation to optimize mechanical stability, however adding anterior column support at L5-S1 can provide sufficient mechanical stability obviating the need for additional pelvic instrumentation and their associated risks. This study investigates the mechanical stability achieved when using the minimally invasive antepsoas (MIS-ATP) approach with percutaneous posterior fixation for L2-S1 fusion without the use of pelvic fixation. Material and Methods: This is a retrospective chart review study of patients who underwent the MIS-ATP approach with percutaneous posterior pedicle screw-rods fixation at L2-S1. These patients were evaluated for demographic data including age, sex, BMI, and smoking history. Hardware complications (such as screws lucency, pseudarthrosis, adjacent segment disease, etc.) were noted, along with consequent need for revision surgery. Statistical analysis was then performed to determine if certain factors (eg. smoking history and/or obesity, etc.) are predictive of hardware-related complications. Results: Seventy patients [Average age: 66 years, 37 (53%) Females, Average BMI: 30.7, Obese Patients: 32 (45.7%), Average follow-up length: 1.7 years, Smokers: 34 (48.6%)] were included in this study. There were 12 patients (17%) who experienced asymptomatic radiographic changes: Proximal (T12-L2) adjacent segment degeneration (6 cases), pedicle screw lucency (3 total cases: 2 at L2 and 1 at S1), cage subsidence (1 case), L2 pedicle screw migration (1 case), and longitudinal rod-screw cap disconnection (1 case). There were 7 (10%) patients with complications that required revision surgery: T12-L2 adjacent segment disease requiring extension of fusion to T10 (4 cases), L5-S1 pseudarthrosis with hardware loosening (2 cases), one of which requiring posterior L5-S1 fusion with iliac screw fixation and the other requiring anterior L5-S1 corpectomy-fusion with iliac screw fixation, and proximal (L1-L2) junctional kyphosis with stenosis (1 case), requiring extension of fusion to T11. Smoking was a statistically insignificant (P > .05) risk factor for developing complications (Odds Ratio: 1.7, P = .3) and these complications needing revision surgery (Odds Ratio: 1.1, P = 1.0). Likewise, obesity was a statistically insignificant risk factor for complications (Odds Ratio: 2.0, P = .2) and these complications needing revision surgery (Odds Ratio: 2.7, P = .3). Conclusion: The relatively low rate of complications requiring revision surgery (10%), indicates that the MIS-ATP provided anterior column support confers sufficient mechanical stability obviating the need for additional pelvic fixation. Neither smoking history nor obesity were statistically predictive of complications or these complications requiring revision surgery (P > .05).

1847

P536: Intravenous Lidocaine for Analgesia in Spine Surgery: A Meta-Analysis of Randomized Controlled Trials

Aryan Haratian ¹ , Arif Musa ² , Saif Farhan ³ , Ryan Field ⁴ , Carlin Lee ⁵ , Collin Bennet ² , Christopher Cooke ⁶ , Rakesh Patel ⁷ , Ilyas Aleem ⁷ , and Samuel Bederman ⁸

¹ University of California, Irvine, School of Medicine, Irvine, USA

² Wayne State University, School of Medicine, Detroit, USA

³ University of California, Davis, Department of Orthopedic Surgery, Davis, USA

⁴ University, of California, Irvine, Department of Anesthesiology, Irvine, USA

⁵ University of California, Irvine, Department of Surgery, Orange, USA

⁶ Detroit Medical Center, Department of Orthopaedic Surgery, Detroit, USA

⁷ University of Michigan, Ann Arbor, Ann Arbor, USA

⁸ Restore Orthopedics, Orange, USA

Introduction: Postoperative pain management after spine surgery remains a challenge for providers. The etiology of pain is thought to be multifactorial stemming from both direct surgical trauma and the resulting inflammatory response. Opioids continue to remain the gold standard of analgesia after spine surgery but carry the risk of respiratory depression, sedation, constipation, and postoperative nausea and vomiting often leading to longer hospital stays. Lidocaine is a commonly used local anesthetic agent that has been shown to have both anti-inflammatory, analgesic, and antiemetic properties, however its effectiveness as an adjunctive analgesic in spine surgery patients remains controversial. This aim of this study was to evaluate the role of intravenous lidocaine as a supplemental pain control modality in patients undergoing spine surgery. Methods: We conducted a meta-analysis of randomized controlled trials (RCTs) involving the use of supplemental intravenous lidocaine in spine surgery. We developed a comprehensive search strategy to adequately screen for randomized controlled trials involving intravenous lidocaine in spine surgery patient in USA National Library of Medicine PubMed/MEDLINE, Clinicaltrials.gov, Cochrane Library Central Register of Controlled Trials, CINAHL (Cumulative Index to Nursing and Allied Health Literature), Clarivate Analytics Web of Science, and World Health Organization International Clinical Trial Registry Platform (WHO ICTRP). Continuous outcomes included postoperative opiate consumption and postoperative pain scores. Dichotomous outcomes included nausea, vomiting, pneumonia, delirium, and wound infection. Results: A total of three randomized controlled trials (RCTs) comprising 235 patients were selected for inclusion in the meta-analysis. Cumulative morphine consumption at 48 hours was not statistically significant between lidocaine and control groups. There were no statistically significant differences in pain scores at any measured time points in the first and second day postoperatively. There were no statistical differences in postoperative complications including nausea, vomiting, pneumonia, delirium, or surgical site infection. Discussion: Our results indicate that literature currently does not support the use of intravenous lidocaine as an adjunctive measure of pain management after spine surgery. Given the relatively few number of RCTs in this field, it is possible that our study was underpowered in detecting a significant difference in the measured outcomes, as our results did trend towards favoring the lidocaine group. Additionally, given the scarcity of current literature and no widely accepted standardized dose for intravenous lidocaine, each of the studies included used a different dosing regimen, which questions if the lack of response was due to an insufficient dose of medication given. Finally, while all of the RCTs included patients undergoing spine surgery, there were noted differences in the surgical complexity of the procedures between the studies which may have been a possible source of error. Overall, further randomized controlled trials are needed to make a definitive conclusion on the effectiveness of lidocaine in spine surgery patients.

1854

P537: Dural Teras in Lumbar Spine Surgery: Incidence, Predictive Factors and Prognostic Impact

Mouadh Nefiss ¹ , Bousrih Anis ¹ , Ben Ayed Mehdi ¹ , Ayari Sakr ¹ , Ezzaouia Khelil ¹ , Bouzidi Ramzi ¹ , and Tborbi Anis ¹

¹ Mongi Slim Hospital, Orthopedic Surgery Department, La Marsa, Tunisia

Introduction: Accidental dural tears with cerebrospinal fluid (CSF) outflow are a common complication in lumbar spine surgery. Its incidence varies widely in the literature (1% -17%), but the management of this complication and its impact on post-operative outcomes have been less studied. The objective of our work was to study the incidence of dural tears in lumbar spine surgery, factors predictive of its occurrence and its impact on post-operative outcomes. Material and Methods: We performed a retrospective study on 109 patients who underwent lumbar spine surgery between January 2015 and June 2019. We collected epidemiological, clinical and imaging parameters that may represent risk factors for the occurrence of a dural tear. Post-operative complications related to dural tear were studied and compared with those of the control group. Results: The incidence of dural tears in lumbar spine surgery in our series reached 16.8%. Suture with 5.0 prolene was performed in 11 cases, 7 patients had a fat flap and biological glue was used in 2 cases. A strict rest between 3 days and 2 weeks is still prescribed in our department. We found that the patients who had an intraoperative procedure to manage the tear had fewer complications than those who had the tear respected (P < .001). Lumbar canal surgery was the most frequent provider of dural tears, including one case with spina bifida not diagnosed pre-operatively. Only one patient was resumed for pseudomeningocele that interfered with the dorsal decubitus and did not resolve spontaneously. Only one productive fistula was noted, which spontaneously dried up after 15 days. We noted no cases of meningitis or epidural abscesses. Prolonged drainage significantly increased the incidence of headache, nausea and delayed wound healing, especially in younger patients. Prolonged surgical time associated with a dural tears increased the risk of surgical site infection and length of hospitalization. Conclusion: Surgery of the lumbar spine, especially in the case of stenosis, can be complicated by a dural gap. Apart from the short-term embarrassing symptoms in the postoperative period, sequelae are often rare. An intraoperative procedure to manage the tears is useful to reduce symptoms related to CSF leakage and prevent other complications, while prolonged drainage may be unnecessary.

1900

P538: Racial Disparities in Readmission Rates Following ACDF Surgery at a Tertiary Care Center

Thaddeus Woodard ¹ , Brian Cortese ¹ , Sachin Gupta ² , Sarthak Mohanty ¹ , Rohan Palanki ¹ , David Casper ² , and Comron Saifi ²

¹ Perelman School of Medicine, Philadelphia, USA

² Department of Orthopaedic Surgery at the Hospital of the University of Pennsylvania, Philadelphia, USA

Introduction: With the US population aging, orthopaedic care has become increasingly prevalent and costly. Several studies have examined outcome measures such as the rate of readmission especially following spinal surgery. However, few have examined how such outcomes differ depending on race. This novel study examines the influence of race on readmission rate following anterior cervical discectomy and fusion (ACDF) surgery. We hypothesized that black patients would have increased ACDF readmission rates based on historical racial disparities in surgical outcomes. Material and Methods: Utilizing a database from three, tertiary care facilities, 311 consecutive patients undergoing anterior cervical discectomy and fusion (ACDF) between 2013 and 2018 were identified retrospectively. The primary outcome of interest was all-cause postoperative readmission by postoperative day (POD) 30 and POD 90. Pre-operative health status was recorded, and comorbidities were scored by the Charlson Comorbidity Index. Demographic data including age at time of surgery, sex, smoking status, and self-identified race (White, Black, and non-Black minority) were abstracted from patient records. Variance inflation factors (VIF) were calculated to assess multicollinearity between potential predictors of readmission. The predictors that showed VIF < 10 were retained for univariate logistic regression analyses. Quartiles were created for age cohort, Charlson comorbidity score, and the length of the hospital stay following operation. Univariate logistic regression analyses were conducted, and subsequent stepwise selection was performed in which a significance level of .05 was required for a variable to stay in the model. Statistical significance is defined by the two-sided test with a P-value <.05 for predictors in the final multivariate models. Results: Of the 311 ACDF patients, 66.9% (208) identified as white, 26.7% (83) identified as black, and 6.4% (20) identified as other non-black minorities. Black ACDF patients were found to be 2.9 years younger (P = .043) than white ACDF. Additionally, black ACDF patients were more likely to be current smokers at time of surgery (P = .001). Adjusted multivariable analysis showed black patients had increased readmission rates compared to white patients at both POD 30 [OR: 5.93 (C.I.: 1.95-18.09); P = .002] and at POD 90 [OR: 3.92 (C.I.: 1.48-10.37); P = .006]. Length of stay post-op after ACDF, when stratified by quartiles, showed increased readmission rate for patients who had the longest lengths of stay compared with patients who had the shortest length of stay at both POD 30 [OR: 10.33 (C.I.: 1.26-84.64); P = .03] and at POD 90 [OR: 7.09 (C.I.: 1.51-33.32); P = .01]. Similarly, patient age at ACDF, when stratified by quartiles, showed increased readmission rate for the oldest patients when compared to the youngest patients at both POD 30 [OR: 4.63 (C.I.: 1.21-17.78); P = .03] and at POD 90 [OR: 4.00 (C.I.: 1.22-13.11); P = .02]. Conclusion: As hypothesized, black patients had higher rates of readmission compared to white patients following ACDF surgeries despite being younger on average. Identification of high-risk populations for readmission would enable healthcare systems to counsel patients more extensively to set expectations for an episode of care and identify pitfalls. Additional research should focus on interventions that can address such disparities to improve outcomes, decrease readmission rates and healthcare costs.

1921

P539: Rare Intracranial Complication Following Cervical Spine Surgery

Hanan AL-Gethami ¹ , and Edward Kachur ²

¹ McMaster University, Neurosurgery, Hamilton, Canada

² McMaster University, Hamilton General Hospital, Neurosurgery, Hamilton, Canada

Cerebrospinal fluid leakage can occur as a complication of spine surgery, and it may lead to serious intracranial complications including hemorrhage. We report a case of 72 years old male who presented with neck pain, numbness and weakness of both hands, greater on the right side, along with walking difficulties. His neurological exam revealed mild weakness of intrinsic hand muscles bilaterally, and weakness of right hip flexion. Besides the presence of myelopathic signs included bilateral Hoffman sign and hyperreflexia in all four limbs. Pre-operative magnetic resonance imaging (MRI) cervical spine scan showed significant stenosis at the level of C3-C5 with spinal cord myelomalacia. He underwent a posterior cervical decompression with instrumentation and fusion from C3-C5. A dural tear was encountered in the surgery during decompressing the lamina of C5 which resulted in a sudden gush of cerebrospinal fluid (CSF) on the right-side posterior to C5. The CSF leak was managed by applying cottonoids followed by a 5-0 prolene primary closure with .5 cc of fibrin glue. Few minutes after the surgery, the patient developed generalized tonic-clonic seizures. As a result, he was intubated and transferred to the Intensive Care Unit. Computerized tomography (CT) scan showed intracranial pneumocephalus along with right acute subdural hematoma, and subarachnoid hemorrhage. The patient seizures were managed with sedation and antiepileptics. He had a full recovery and improved with physiotherapy. This case illustrates the potential for intracranial hemorrhage after the intraoperative dural tear and CSF leak manifested by generalized seizures. Recognition of this complication is critical to the institution of appropriate therapy and prevention of any fatal consequences.

1925

P540: The Effects of Preoperative Mental Health Scores on SRS-22 and Postoperative Outcomes in Adult Spinal Deformity Surgeries

Cole Morrissette ¹ , Paul Park ¹ , Meghan Cerpa ¹ , and Lawrence Lenke ¹

¹ Columbia University, New York, USA

Introduction: The objective of this study was to determine the relationship between preoperative mental health Scoliosis Research Society (SRS)-22r questionnaire scores and postoperative outcomes, with the hypothesis that higher mental health baseline scores would have positive impacts on postsurgical outcomes. Methods: A retrospective, cohort study of 96 patients undergoing primary adult spinal deformity surgery between August 2015 and April 2020 were used for this study. They were categorized into either high mental health (HMH) or low mental health (LMH) cohorts based off a baseline mental health score on SRS-22 of ≥4 or <4, respectively. Postoperative complications and outcomes were then compared between the HMH and LMH groups including changes in follow-up SRS-22 scores, ODI scores, lengths of stay, readmission rates, discharge locations, and revision rates. Results: Length of stay was significantly increased in LMH patients (HMH = 5.53 days, LMH = 7.06 days, P = .045). There was no significant difference between HMH and LMH patients for readmission rates at 30 days (P = .78), readmission at 90 days (P = .83), discharge location (P = .07), or satisfaction with management (P = .92). LMH patients had significantly greater improvements in SRS (P =< .001) and ODI (P = .02) scores from baseline to follow up. However, HMH patients had higher absolute values for their postoperative SRS scores (P = .01). There was no difference in follow-up ODI scores between HMH and LMH patients (P = .11). Conclusions: The total length of stay is significantly increased for patients with lower preoperative mental health scores. There appears to be no significant relationship between baseline preoperative mental health scores and readmissions, revision surgeries, discharge locations or satisfaction with management. However, given the minimal readmission and revision rates, this study may be underpowered to make a conclusive statement on this matter. Despite the greater improvements in SRS and ODI scores for LMH patients, likely due to a greater capacity for improvement, HMH patients have higher overall SRS scores postoperatively, indicating preoperative mental health may influence postoperative subjective quality of life scores.

Trauma—Cervical

160

P541: Incidence and Independent Predictors for Cervical Spine Injury in Traumatic Brain Injury

David Yuen-chung CHAN ¹ , Yuzhong He ¹ , Wai Sang Poon ¹ , Colin Alexander Graham ² , Janice Hiu Hung Yeung ³ , Nai Kwong Cheung ³ , Wai Kit Mak ¹ , Danny Tat Ming Chan ¹ , and George Kwok Chu Wong ¹

¹ Prince of Wales Hospital, Division of Neurosurgery, Department of Surgery, Hong Kong, Hong Kong

² Accident and Emergency Medicine Academic Unit, The Chinese University of Hong Kong, Hong Kong, Hong Kong

³ Prince of Wales Hospital, Accident and Emergency Department, Hong Kong, Hong Kong

Introduction: It is important to rule out cervical spine injuries in patients with head injuries. There was considerable variation in the clinical practice of imaging the cervical spine. The specific incidence of cervical spine injury in significant head injury patients was uncertain. Methods: Consecutive patients with head injury admitted via the Accident and Emergency Departments to Prince of Wales Hospital from 1 January 2014 to 31 December 2016 were retrospectively reviewed. The trauma registry was maintained by a trauma specialist nurse coordinator. The inclusion criteria included the presence of head injury with the Abbreviated Injury Scale (AIS) of Head and Neck score ≥ 2 (i.e. head injuries with intracranial hematoma or skull fracture) and age >= 16 years old. Exclusion criteria including those with minor head injury with only scalp abrasions or superficial lacerations without significant intracranial injuries (i.e. head injury AIS score = 1). The primary outcome was the incidence of cervical spinal injury in head injury patients. Secondary outcomes included 30-day mortality rates. Univariate and multivariate analysis were conducted to identify independent predictors associated with spinal injuries in head injury patients. Results: In total 1105 patients fulfilling the inclusion and exclusion criteria were identified over the study period. The mean age was 58.8 years old (SD = 21.22). 11.2% had cervical spinal injuries (124/1105). Severe head injury (GCS 3-8) had the highest rate of cervical spinal fracture at 10.8%. The 30-day mortality rate for head injury patients with cervical spinal injury was 10.5%. Multivariate analysis identified low GCS (P = .030) and mechanism of injuries with either high-fall (>2 metres) or motor vehicle accidents (P = .001) were independent predictors for the presence of spinal injury in head injury patients. However, the presence of skull fracture (P = .007) was inversely associated with the presence of spinal injury in head injury patients. Conclusions: 11.2% of significant head injury patients (presence of intracranial hematoma or skull fracture) had cervical spinal injuries. Low GCS and mechanism of injury are independent predictors for the presence of spinal injury. On the other hand, the presence of skull fracture (P = .007) was inversely correlated with the presence of cervical spinal injuries in head injury patients.

196

P542: Dorsal Fusion as Correction of Craniocervical Instability in Patients With Traumatic Lesions

Nikolay Mirchev ¹ , Orlin Pavlov ² , and Robert Behr ³

¹ Klinikum Fulda gAG, Neurosurgery, Fulda, Germany

² Klinikum Fulda gAG, Neurosurgery, Fulda, Germany

³ klinikum Fulda gAG, Neurosurgery, Fulda, Germany

Introduction: A retrospective and prospective analysis of the surgical treatment and results of 109 patients with traumatic craniocervical, atlantoaxial lesions operated during 8-years period (2011-2018) at our Department was performed. The aim of the analysis was to assess the factors affecting dorsal fusion as correction of craniocervical and high cervical instability. Material and Methods: The mean age of the patients was 62 years. The female to male ratio was 1:1,5. We analyzed 109 patients with traumatic lesions and we found 69 odontoid fracture II Type, 21 Hangman fracture and 19 combined craniocervical and atlantoaxial fracture. Results: In 109 patients we performed 114 operations. Because of craniocervical/cervical instability we made posterior screw fixation in all of 109 patients. In 27 patients we performed additionally decompressive laminectomy. In order to improve screw placement accuracy we performed intraoperative O-Arm in 91 cases. The operative duration was 2 h. in O-Arm operations and 4.20 h in C-arm operation. The blot loss was 250 ml in O-Arm and 550ml in C-Arm procedures. The most common operative complications were: CSF leak – in 1 case, postoperative infection – in 5 cases, screw misplacement - in 2 cases and without early operative mortality. The 24-monts follow-up showed good recovery in 75 patients, moderate disabling in 25 patients, severe disabling in 4 patients, vegetative state in 2 patients, death in 3 patients with bad general condition. Conclusions: Early correction of craniocervical and high cervical instability facilitated neurological recovery by preserving the existent neurological function. Using of O-Arm increase significant operative screw placement accuracy, and preserve intraoperative nerve and vertebral artery injury. Fusion was achieved in all patients. Recently because of the improvement of neuroimaging techniques, operative approaches, surgical techniques and neurointensive care the results of treatment of these lesions are optimal.

284

P543: Outcome of Conservative Treatment in Central Cord Syndrome

Takahiro Tanaka ¹

¹ Shonan Kamakura General Hospital, Neurosurgery, Kamakura, Japan

Introduction: Central cord syndrome (CCS) is the most common type of incomplete traumatic spinal cord injury. However, clinical management and the timing for surgery in CCS patients still remains unclear. We investigated the outcome of conservative treatment in CCS patients. Material and Methods: There were 39 patients could follow up over six months from January 2014 to December 2019. Our surgical indication is little improvement by conservative management over two weeks and patient's request. 36 cases could improve by only conservative treatment, so we investigated these patients. General condition was evaluated by American Society of Anesthesiologists (ASA) physical status classification, and pre and post operative neurological symptoms were evaluated using upper and lower extremity function and upper extremity sensory function in Japanese Orthopaedic Association (JOA) scoring system for cervical myelopathy. Final outcome was evaluated by Nurick Scale. Results: The average age is 71.2. The average follow-up months was 19.2months. 10 cases belonged to ASA class 1, 14 cases were class 2 and 12 cases were class 3. In JOA score, upper (1.4 to 3.3; P < .0001) and lower (-.30 to -.02; P < .05) extremity function, upper extremity sensory function (.85 to 1.58; P < .0001) were improved significantly. In Nurick Scale, 12 cases belonged to Grade 0, 20 cases were Grade 1 and four cases were Grade 3. Conclusion: Conservative treatment could improve upper motor and sensory function significantly. We recommend conservative treatment for CCS patients in their acute phase. If their neurological function could not improve or worsen after conservative management, decompression surgery should take into consideration.

319

P544: Floating Cervical Spine Injuries: Cranio Cervical Dissociation With Associated Unstable Sub-Axial Spine Fracture

Celeste Tavolaro ¹ , Mario Taylor ¹ , Carlo Bellabarba ¹ , and Richard Bransford ¹

¹ Harborview Medical Center, Orthopaedics and Sport Medicine, Seattle, USA

Introduction: The purpose of this study was (i) to first describe the floating spine along with the mechanism of injury, frequent injury levels, and neurological deficits; and (ii) to determine the most effective method of treatment.Material and Methods:After IRB approval, we conducted a retrospective study including all the patients whom sustained a craniocervicaldissociation injury in association with another unstable spine injury between January 1^st2003and August 31th 2018. We retrospectively identified the patients from the hospital trauma registry. Patients were included if full spine CT or MRI were performed. A detailed review of the imaging studies was performed to collect information regards the spine injuries localization and type. Craniocervicaldissociation (CCD) was defined as the distraction injuries sustained between the skull base and the second cervical vertebra. There is a variety in the presentation CCDincluding injuries that involve the atlanto-occipital level or the atlantoaxial level or both. An unstable spine injury was defined a spine injury that involved three spine columns sustained between the subaxial cervical and upper thoracic spine (C3-T4). Demographic data, mechanism of injury, neurological status, type of treatment, follow up and patient outcomes were obtained from the electronical medical records.Results: Overall, 117 patients with CCD were identified from the hospital registries. Twelve patients with known CCD died during initial work up at the ED prior to full spine radiographic work-up. 105 patients with CCD had full spine radiographs, and 16 patients were identified as having an associated unstable sub-axial injury between C3 and T4. Eleven patients were male and five were female with mean age of 45.4 ± 19 years.All the patients were involved in high-energy trauma including: motor vehicular collision (9), pedestrian struck by car (3), motorcycle collision (3) and snowmobile collision (1). The most common noncontiguous level associated to the CCD was C6-C7 (9 patients). Surgical treatment was indicated for all the cases. In nine patients the instrumentation of the two noncontiguous injuries were performed in a single setting. In five cases the distraction injury was fixed before that the CCD, due to the size of the gap of the distraction and instability. Short segmented posterior instrumentation and fusion was the elected surgical treatment in the majority of the cases (58%). There were 9 survivors with an average follow up of 2 years. Three patients died during the initial work up at the emergency department, and three within 15 days after spine surgery. Conclusion: Floating spine injury results from a high energy injury and involves distraction mechanism alone or in association with a flexion or extension force. In our series, 20% of the patients with craniocervicaldissociation had associated another noncontiguous unstable spine injury. Routine full spine CT in patients with CCI should be performed. Due to the nature of the injury, neurological deficits are expected. Fixation of both injuries through a unique surgical stage should be the goal. Severe distracted injuries should be stabilized first. Posterior segmental spinal instrumented fusion showed to be the elected fixation method.

328

P545: Compressive Extension Injuries of the Subaxial Cervical Spine: Do We Really Understand the Nuances of This Injury?

Eric Rebich ¹ , Celeste Tavolaro ¹ , Jay Yao ¹ , Haitao Zhou ¹ , Richard Bransford ¹ , and Carlo Bellabarba ¹

¹ Harborview Medical Center, Orthopaedics and Sport Medicine, Seattle, USA

Introduction: Allen et al. described 6 patterns of subaxial cervical spine fractures and dislocations using plain radiographs, based on mechanism of injury. Compressive Extension (CE) injuries were categorized into five progressive stages, of which stage 4 (CE4) and 5 (CE5), have been described as having a posterior vertebral arch fracture accompanied by translational displacement (dislocation) of the vertebral body. However, CE4 was described only as a hypothetical stage, while only 3 patients were found to have CE5 injuries; thus, very little is understood about these injuries. Aim: To identify characteristics of compression extension injuries with vertebral body displacement (CE4 and CE5) from a series of surgically treated subaxial cervical spine fractures. A secondary aim was to identify characteristics that may guide the treatment and/or affect the prognosis. Material and Methods: After IRB approval, patients with CE injuries were identified through billing data at a level I trauma center between 2005 and 2018. Demographic data, ISS, ASA, motor score, and complications during the hospitalization were collected from the patient’s EMR. CT scans were reviewed to assess fracture pattern, level, and location of the vertebral arch fracture, vertebral body displacement, spinal canal diameter and method of surgical stabilization. Injuries were classified according to the classification of Allen et al. Results: 2,117 patients underwent operative treatment of the subaxial cervical spine, of which 980 patients had been diagnosed with subaxial cervical spine fractures or dislocations. 221 of these patients had a CE injury mechanism, 24 of which had CE4-CE5. 19 males/5 females; average age 55 years. High energy mechanism occurred in 92% of the patients, with motor vehicle accidents being the most common. Average ISS was 21. ASIA classification was 3 A, 1 B, 1 C, 9 D and 10 E. Preoperative and postoperativeASIA motor scores were 80 and 84 respectively. All CE4 and CE5 injuries occurred at C6-C7 or C7-T1. Average anterolisthesis was 6.26 mm (SD ± 2.3 mm) for CE4 and 16.8 mm (SD ± 1.8 mm) for CE5. Average spinal canal diameter at the level of dislocation was 20 mm (SD ± .4 mm) for CE4 and 30.5 mm (range 29.6-31.4 mm) for CE5. The surgical approach was anterior in 5 patients, posterior in 12 patients, and combined in 7 patients. In four patients the surgical instrumentation was limited to one level and in 20 patients included at least two levels. 30% of patients had complications. Three deaths occurred in the postoperative hospitalization period (7-15 days). Conclusion: CE4 and CE5 injuries represented 10% and 1% of all CE injuries, and affected only the C6-C7 and C7-T1 levels. This fracture pattern typically results in widening of the spinal canal as the anterior displacement of the vertebral body occurs independent of the fractured posterior elements, spinal cord injuries are neither as severe nor as common as in fracture-dislocation from other mechanisms. The average motor score was 80 among all patients with 75% classified as ASIA D or E at presentation in spite of the substantial vertebral column translation observed.

358

P546: Occipitocervical Fusion in a Infant With Atlantooccipital Dislocation Using Autologous Rib Grafts

Bernardo Keuffer ¹ , José Augusto Malheiros Dos Santos Filho ² , Thiago Pereira Andrade ² , Luiz Otoni Garcia ³ , Felipe Mendes Ferreira ¹ , Guilherme Mansur ⁴ , Ellano Pontes ² , and Bruno Pinto Coelho ⁵

¹ Hospital Marcio Cunha - Fundação São Francisco Xavier, Neurocirurgia, IPATINGA, Brazil

² Hospital Felicio Rocho, Neurocirurgia, Belo Horizonte, Brazil

³ hospital Sao Joao De Deus, Neurocirurgia, Divinopolis, Brazil

⁴ hospital Joao Xxiii, Neurocirurgia, Belo Horizonte, Brazil

⁵ Universidade Federal de Ouro Preto, Medicina, Ouro Preto, Brazil

Introduction: The treatment of craniovertebral junction (CVJ) instability in pediatric patients is a big challenge. Cartilaginous and short vertebrae may difficult the use of conventional fixation. The treatment of traumatic atlantooccipital dislocation (AOD), most part of time, is surgical stabilization and arthrodesis of the occipitocervical complex. Cervical arthrodesis in the pediatric age group can limit growth and lead to deformities. There are many techniques described for stabilizing this region. The majority part of them rely on corticocancellous iliac crest. Materials and Methods: We present a case report of a child with AOD with gross instability, who was submitted to occipitocervical arthrodesis using autologous ribs fixed with titanium miniplates. Results: Postoperative imaging tests of the cervical spine demonstrated excellent occipitocervical alignment in addition to complete bone fusion at the end of 12 months of follow-up. Conclusions: This case report illustrates the successful application of occipitocervical fusion using autologous rib fixed with titanium plates. This a versatile and stable technique for craniovertebral junction in children. There is bone fusion without impeding the growth.

766

P547: Outcome of Anterior Decompression, Bone Grafting and Plating in Sub-Axial Cervical Spine Injury

Kyaw Linn Linn ¹ and Sai Rath ¹

¹ Yangon General Hospital, Yangon, Myanmar

Introduction: Trauma to the spine is increasingly common in young healthy population in developing countries. Among those spinal injured patients, more than half of cases involve the cervical spine, 40% of which occurs in C6 and C7 regions. Because of differences in spinal canal dimensions and the mechanisms of injury, spinal cord damage is more frequently associated in sub-axial cervical region and these are usually treated surgically or non-operatively. The goals of surgical treatment are maintenance of neurological function, prevention of additional functional loss and restoration of spinal stability with bony fusion (Rizzi et al, 2015). Surgical treatment by means of reduction, arthrodesis and fixation of injured vertebral segment has been recommended as the method of choice. However, no consensus exists about the best approach, with preferences divided into anterior or posterior approach (Helton et al,2007). The aim of the study was to study the outcome evaluate the outcome of anterior decompression, bone graft and plating in subaxial cervical spine injury at Yangon General Hospital, Myanmar. Material and Methods: It is prospective descriptive study to evaluate the outcome of anterior decompression, bone graft and plating in subaxial cervical spine injury. The outcome of 26 patients treated with anterior decompression, bone graft and plating in subaxial cervical spine injury between January 2017 and June 2018 at Yangon General Hospital were assessed. The clinical and radiological follow up were carefully evaluated and analyzed. Results: Among 26 patients of the study group, the most common age group was 30 to 40 years in which 12 patients (46.2%) of study population. 92.3% (24) of the study population were male and 7.7% (2) was female. The most common mechanism of injury was RTA:61.5% (16 cases). The most common injured level was C5-61.6%(16 cases) followed by C6-23.1%(6) and C7-15.4%(4). In Neurological Assessment by ASIA Score, 61.6% (16 cases) showed no ASIA changes and 38.5% (10 cases) showed ASIA improvement. In neck pain assessment by VAS score, mean preoperative VAS score was 8.16 and reduced gradually at the 3 month and 6 month postoperatively. Pre-operative cervical kyphosis was improved from mean of -3.3 degree to mean 11-degree. Plates and screws of varying sizes were used depending on injury pattern and bone stock. Good bony fusion was observed in all patients. No neurologic or vascular injury was noted clinically. The follow up period was 12 months. Conclusion: Our study showed that anterior decompression, bone graft and plating is safe and effective technique in the treatment of subaxial cervical spine injury. The limiting factors in this study were small study group and shorter follow-up period. The avoidance of neurovascular injury and minimal instrument failure rate in this study proved that our techniques are safe and able to achieve rigid fixation with a very low complication rate. A further advantage, the procedure requires a shorter learning period and is a more straight forward surgical procedure. Longer follow up time are required to confirm the value and satisfactory results of our technique.

794

P548: Changes in Functional Neurological Status in Complete (ASIA A) Traumatic Cervical Spinal Cord Injury Patients: Results in 633, Prospectively Accrued Cases From a Multicentre, International Dataset

Ali Moghaddamjou ¹ , Jetan Badhiwala ¹ , Jefferson Wilson ^1,2 , and Michael Fehlings ^1,3

¹ University of Toronto, Neurosurgery, Toronto, Canada

² Unity Health Toronto, Toronto, Canada

³ University Health Network, Toronto, Canada

Introduction: Traumatic spinal cord injury (SCI) is commonly classified and studied using the American Spinal Injury Association (ASIA) Impairment Scale (AIS). Conversions between ASIA grades are often used as a positive clinical indicator. This is particularly relevant in the motor and sensory complete patients (ASIA A) as any conversion in this population would have significant functional implications. Knowing the changes in conversion rates over time is relevant for setting patient expectations, for understanding the natural history of cervical traumatic SCI (TSCI) and to inform clinical care pathways. Material and Methods: Patients with motor and sensory complete cervical TSCI were identified from 4 prospective, multi-center SCI datasets (NACTN, STASCIS, Sygen, and NASCIS III). Patients who had missing baseline exams or were over the age of 80 and under the age of 16 were excluded from the analysis. Examinations were stratified into four categories based on time of exam (Baseline, < 72hrs, two weeks, 1 month, 3 months, 6 months, and 1 year+). At each time category, ASIA A patients were selected, and their best available subsequent ASIA grades were tabulated. Conversion rates from ASIA A to B and from motor complete to incomplete (C, D, E) were calculated at each time point. Results: In total we identified 633 ASIA A cervical TSCI patients who met our inclusion criteria: 159 were from the NACTN/STASCIS registries, 140 from NASCIS 3 and 334 from the Sygen study. Average patients age for Sygen and NASCIS 3 were 32.46 years and 34.41 years respectively while the NACTN /STASCIS patients had an average age of 43.36 years. The NACTN/STASCIS patients had on average less time to surgery (24.85hrs) compared to the NASCIS 3 and Sygen patients (134.26 hrs and 217.38 hrs respectively). Patients who were ASIA A at baseline had a 38.5% conversion rate to higher grade in any subsequent exam (14.53% to ASIA B and 24.01% to ASIA C, D or E). Patients who were ASIA A at 1-month post injury had a conversion rate of 26.98% to a higher grade in subsequent exams (13.08% to ASIA B). Patients who were ASIA A at 3 months post injury had a conversion rate of 13.31% to a higher grade in subsequent exams (7.74% to ASIA B). Conclusion: Using data from 4 prospective, multi-center SCI datasets we were able to report an ASIA A conversion rate of 38.5% from baseline for cervical TSCI patients, which is higher than conventionally thought and which supports the concept that these patients merit aggressive surgical and medical treatment. Further work is required to identify the key factors which predict ASIA conversion in these critically injured patients.

821

P549: Traumatic Central Cord Syndrome (CCS): Results in Workers' Compensation Patients

Javier Lecaros ¹ , César Wilson ¹ , Marcos Gimbernat ¹ , Ignacio Cirillo ¹ , Gabriel Hernández ¹ , and Vicente Ballesteros ¹

¹ Hospital del Trabajador, Santiago, Chile

Introduction: The CCS is an incomplete spinal cord injury, often secondary to low energy traumas in patients with degenerative cervical disease. Literature describing the outcomes of workers’ compensation patients is scant. Our purpose is to describe the mechanism of injury, clinical presentation, neurological deficit and the outcomes of the treatment of this type of lesion. Material and Methods: We reviewed the database of patients with cervical spine trauma between 2010 and 2019 identifying those with CCS. Demographic data, clinical presentation, time to surgery, NASCIS II protocol application, ASIA score, motor index score (MIS) and the bladder/bowel dysfunction were described. Results: The average age was 56 (range 42-71) years old in eight men and one woman. The most common mechanisms were falls from height (44%) and motor vehicle crashes (44%). Most injured level was C5-C6 with 55%, and 44% of the patients had two compromised levels. Eight patients had ASIA D neurological deficit and six had bladder and/or bowel dysfunction. Eighty-eight percent of the cases were treated with surgery and 44% were operated within 24 hours of the accident. Protocol NASCIS II was applied in 33% of the cases. At the end of the average follow-up of 30 (range 4-104) months, 44% recovered one grade in the ASIA score and 30% remained without motor deficit. Finally, half of the patients recovered the bowel/bladder function in a variable degree. Conclusion: In workers’ compensation patients, the CCS is a consequence of a high-energy trauma. Near half of the cases had two or more levels injured. Thirty percent and 50% of these patients completely recovered the motor and the bladder/bowel function, respectively.

1086

P550: Surgical Management of Neglected Irreducible Bifacetal Cervical Dislocation With Reduction Screw

Jayesh Pawar ¹ , Dr Mihir Bapat ¹ , and Arpit Upadhyay ¹

¹ Nanavati Hospiatl, Spine, Mumbai, India

Introduction: Subaxial cervical spine injuries are often missed on the primary trauma survey. However, there is a relative paucity of published clinical data regarding the treatment of neglected bifacetal cervical dislocation (more than 3 weeks). A neglected dislocation remains unstable and has a potential risk of spinal cord injury. An ensuing fibrous union, makes reduction and surgical stabilisation difficult. The guidelines are not clearly defined. Our technique minimizes the total number of necessary procedures and differs in sequence from previously reported methods We report a series of 5 cases of these rare injuries. The steps in the surgical management and outcomes are elaborated. Material and Methods: Between 2014 and January 2019, 5 patients with neglected bifacetal dislocation underwent operative treatments and were followed-up for at least 1 years. A posterior procedure was conducted first, comprised of soft tissue release, facetectomy and reduction with help of reduction screw. Subsequent anterior procedure included soft tissue release, discectomy, reduction, intervertebral grafting, and anterior plating. One functional spinal unit was fused in this group. Neck pain, neurologic status, operating time, blood loss hospital stay and correction on radiographs were recorded through- out the patient’s course. Results: All five patients were operated under general anaesthesia in same sitting by two approaches posterior and anterior. Preoperative closed reduction was not attempted in any of the patients. The mean operating time was 303 minutes and the mean blood loss was 172 ml. All patients were subsequently discharged on the fourth post operative day The mean preoperative kyphosis 37.2 degree was corrected in all patients after the surgery to mean postoperative 6.6 degree lordosis and was maintained over 7 degree throughout one year follow-up. NDI and VAS score were significantly improved immediately after surgery and at last follow-up, as compared with preoperative score (P < .05). Three patients with worsening of neurology were improved completely at final follow up. Conclusion: Irrespective of the level of injury, all patients with neglected bifacetal dislocation can be safely and effectively reduced by this technique. Adequate soft tissue release, partial facetectomy and ability to reduce the vertebral bodies with lateral mass reduction screw are the key elements in this technique. Also it provides greatest mechanical stability without fusing the normal motion segments. Moreover there is minimal blood loss, shorter hospital stay, early mobilisation and rehabilitation and need of turning the patient only once throughout thr procedure. At one year follow-up, all patients had complete fusion occurred across the operative level.

1138

P551: Feasibility Safety and Outcomes of a Proposed Surgical Treatment Algorithm for the Management of Neglected Irreducible Facet Dislocations of the Sub-Axial Cervical Spine

Aju Bosco ¹ and Nalli Ramanathan Uvaraj ¹

¹ Madras Medical College, Orthopedic Spine Surgery Unit, Chennai, India

Introduction: The management of neglected post-traumatic facet dislocations (AO type F4 injury) of the sub-axial cervical spine presenting beyond three weeks since injury is challenging, due to the difficulty in achieving reduction of the subluxated or dislocated facets. Though different surgical strategies have been described in literature for the management of post-traumatic cervical facet dislocations of the subaxial cervical spine presenting at or beyond 3 weeks since injury none are effective in all scenarios, with varying rates of success in achieving reduction of the facet dislocation. We describe an effective surgical treatment algorithm for the management of neglected post-traumatic sub-axial cervical facet dislocations and have analysed its efficacy, safety and outcomes. Materials and Methods: This is a retrospective review of a prospectively treated cohort of twenty-four patients (11 males,13 females) with a mean age of 42.6 ± 14.5 (range, 36-53) years, who presented with neglected (presented at three weeks or more since injury) facet dislocations of the sub-axial cervical spine. Following a trial of failed closed reduction, open reduction was carried out as a three-stage procedure under a single anaesthesia (Stage-1: release of the cicatrized anterior longitudinal ligament and subsequent anterior cervical discectomy through Smith Robinson approach, Stage-2: release of fibrous tissues and cicatrix around the facets or facetectomy to achieve reduction of the locked facets with concomitant posterior stabilization, Stage-3: anterior reconstruction with tricortical iliac crest autograft and locking plate through Smith Robinson approach). Outcomes were assessed with respect to VAS(Visual Analogue Scale) and NDI(Neck Disability Index) scores, satisfactory reduction and maintenance of alignment on radiographs, with evidence of fusion on radiographs at follow-up. Results: Patients presented at a mean of 7.1 ± 6.7 weeks (range, three weeks to thirty-six weeks) since injury. Fall from height was the most common mode of injury. In total, there were 21 bifacetal and 3 unifacetal dislocations. The mean follow-up was 27.5 ± 2.4 months (range, 25 to 42 months). Twenty patients had complete pain relief at final follow-up. Two patients who presented with ASIA C neurology improved to ASIA E at final follow-up. There was no neurological deterioration in any patient. Radiographs showed satisfactory reduction in 22/24 (91.7%) patients. Radiological evidence of fusion was seen at a mean of 9.2 ± 1.4 months. The spinal alignment was well maintained in all cases at final follow-up. One patient with pull out of screws during follow-up, had an uneventful clinical course with an acceptable spinal alignment. No revision surgeries were needed. VAS and NDI scores showed significant improvement at final follow-up, P < .05. Conclusion: This anterior-posterior-anterior approach is an effective and safe surgical strategy in the management of sub-axial cervical facet dislocations presenting beyond three weeks since injury. It helps in achieving a good reduction (91.7% success rate), satisfactory spinal alignment and fusion with good clinical and functional outcomes, at a mean follow up of 27.5 ± 2.4 months with a minimum follow up of 25 months.

Keywords

cervical spine, facet dislocation, neglected, AO type F4 injury, surgery, approach

1145

P552: Acute Cervical Spine Trauma - A Retrospective Study of Patients Presenting With Cervical Spine Fractures

Slavisa Zagorac ¹ , Uros Novakovic ¹ , Milos Vasic ¹ , Jovana Grupkovic ² , and Goran Tulic ²

¹ Clinical center of Serbia, Department for spinal surgery, Belgrade, Serbia,

² Clinical center of Serbia, Department for musculoskeletal trauma, Belgrade, Serbia

Introduction: Acute cervical spine trauma is a broad term, which encompasses a wide range of injuries to the soft tissues, bones and spinal cord. The mechanism of injury can vary, from falling from different heights, to traffic accidents, resulting in polytrauma. Acute cervical spine trauma is common in both the elderly and the young, as well as athletes, or people who practice recreational sports. One of the most challenging types of injury, from a surgical point of view, is associated with fractures of the cervical vertebrae. This type of injury demands an appropriate and careful evaluation and therapy, because of the severity of possible negative outcomes such as permanent neurological deficit, quadriplegia and death. Materials and Methods: A retrospective study was conducted for 480 patients, admitted to the Department of spinal surgery, Emergency care center, Clinical center of Serbia, and treated for acute cervical spine trauma, from September 1st 2010 to September 1st 2020. The data collected included: gender, age, mechanism of trauma, fracture localization, therapy, outcome, and ASIA scores both upon being admitted to hospital and upon being released. Results: Out of 480 patients enrolled in our study, 353 (74%) were male and 127 (26%) were female the mean age was 50.6 years (the youngest 17 and the oldest 86 years old). We’ve concluded that the mean age for men was lower (49.9 ± 18.5). The main cause of trauma were traffic accidents (45%), followed by falls from heights less than 2m (34%), falls from heights greater than 2 m (12%), and other causes (8%). Men were most frequently injured in traffic accidents, while the main cause of od injury for women were falls from heights less than 2m. Most of the fractures of the cervical spine were localize in C2 region (34%), followed by fractures in more than one region (24%), than fractures of C7 (14%), C1 (14%), C3 (6.5%), C6 (4.2%) and C5 (4%). A total of 60 patient (12%) were eligible for surgery out of which 52% patients had multiple fractures of cervical vertebrae, 18% had fractured C3, 15% C7 an 15% C5 vertebral fractures. 50% of the surgically treated patients have shown signs of neurological recovery, while the other 50% remained stationary. Upon admission 82% had scored E on ASIA scale, 6% scored D, 6.5% scored ASIA B and 5.5% scored ASIA A. Upon discharge 84% scored E on ASIA scale, D 6%, C 4.1%, B 4%, A 1.9%. Conclusion: Our study found that there is an increase in cervical fractures in younger population, the male population being predominantly affected. Traffic accidents remain the most common cause of cervical fractures when it comes to men while falls from less than 2m heights singles out as the main cause for women. There is a statistical relevance for positive outcome in patients treated surgically, therefore surgery should be considered whenever possible.

1168

P553: A Unique Case of Bilateral Condyle Fractures Associated With Inferior Clivus Separation Fracture and C1/2 Dissociation Resulting in Cranio-Cervical Dislocation: A Modification of Anderson and Montesano Classification System Is Proposed

Gustavo Carrico ¹ , Khai Lam ¹ , Felipe Nanni ¹ , Felipe Fernandes ¹ , and Carlos De La Torre ¹

¹ London Bridge Hospital, Spine Surgery, London, United Kingdom

Introduction: The most common classification system used in occipital condyle fractures (OCF) was described by Anderson and Montesano¹ in 1988, which divides OCF into 3 different subtypes. A high index of suspicion of this kind of rare injury and appreciation of its fracture subtype variations and clinical presentation helps to guide the spine surgeon towards successful management of these potentially devastating injuries². We report a unique case of bilateral OCF that was associated with complete separation fracture of the inferior clivus resulting in craniocervical dislocation alongside dissociation of C1-C2 joint complex. Material and Methods: A 21-year-old male was involved in a high-energy motor vehicle accident (MVA) and was subsequently ejected 20 meters out of his car. His immediate Glasgow Coma Scale (GCS) was 6 points that required immediate endotracheal intubation. Physical examination revealed a right-sided hemiparesis (2/5 MRC) as well as a large right-sided gluteal sub-fascial haematoma. Immediate CT images revealed bilateral OCF extending to the inferior part of the clivus, fracture of the C1 lateral masses, widening of the atlanto-occipital joint space and disruption of the C1-C2 posterior interspinous distance causing severe craniocervical dissociation with gross instability. MRI showed an anterior non-compressive subarachnoid haematoma starting at the foramen magnum and extending downwards to the level of C5. A halo-vest was immediately put in place before being safely transferred to a tertiary hospital. The patient underwent surgery five days later in the form of a posterior occipito-C1-C2 fixation using C1 lateral mass and C2 pedicle screws. The patient was extubated four days after surgery with improved strength on the left side of 4/5 MRC. At twenty days follow-up the patient was able to walk with assistance. He developed acute hydrocephalus sixty days after surgery secondary to the epidural fibrosis created by the resolving subarachnoid haematoma that required posterior fossa decompression and a ventriculoperitoneal shunt. Two years later the patient was found to be pain free with complete return of his normal neurological function, and CT confirmed full union of the OCF and fusion construct. Results and Conclusion: On review of the English literature, there are only 6 descriptions reporting the association of OCF associated with an avulsion fracture of the inferior clivus (literature will be presented). Our case is particularly unique because the bilateral OCF involved entire ‘en piece’ avulsion of the inferior clivus alongside dissociation of C1-C2 complex resulting in a highly unstable craniocervical dislocation. We propose a new Type IV modification of the Anderson and Montesano classification system with two subtypes of injuries. Type IVA occurs when the OCF is associated a clivus avulsion fracture whilst Type IVB occurs when associated with complete ‘en piece’ separation fracture of the inferior clivus. Both Type IV injuries are considered highly unstable and recommendation for surgical fixation.

1319

P554: Tunisian Experience With the Subaxial Cervical Spine Injury

Yassine Gdoura ¹ , Hariz Liwa ¹ , khalil ayadi ¹ , and Boudawara Mohamed Zaher ¹

¹ Habib Bourguiba Hospital, Neurosurgery, Sfax, Tunisia

Introduction: Injuries to the subaxial cervical spine are relatively frequent and can cause disco-ligamentary and spinal cord injuries. These lesions are related to vital and functional outcome. Purpose of the work is to specify the epidemiological, clinico-radiological, therapeutic and evolutionary characteristics of the population studied in order to propose a diagnostic strategy and a therapeutic attitude for traumas of the subaxial cervical spine. Material and Methods: Our study is retrospective, descriptive and analytical on a series of traumas of the lower cervical spine spanning 6 years (2013 - 2019) treated in the neurosurgery department at Habib Bourguiba Hospital in Sfax - Tunisia. Results: The series includes 130 patients, with a sex ratio of 5.19 and an average age of 40 years. We found 89 traffic road accidents (68.4%). The first medical contact was on the day of the trauma for 114 patients (87.7%). Neck pain was found in 128 patients (98.5%) and tetraparesis / plegia in 37 patients (28.5%). An associated head trauma was found in 55 patients (42.3%). Each patient had standard x-rays, a CT scan, or both exams. Magnetic resonance imaging and dynamic radiographs were used in 58 (44.6%) and 24 (18.5%) patients respectively. The C5 vertebra as well as the mobile spinal segment C5-C6 were affected in 32 (24.6%) and 41 patients (31.5%) respectively. Definitive orthopedic treatment was performed for 54 patients (41.5%) and surgical treatment for 65 patients (50%) including 63 patients operated exclusively by anterior approach to perform arthrodesis and fixation. The death rate was 13.1%. The average length of hospital stay was 8.5 days. The mean time to the last clinical check-up was 13.2 months. Neurological status according to the AIS scale was improved in 25 patients (31%) with full recovery in 17 patients (15%). The average Neck Disability Index was 4 and the average C2-C7 absolute rotation angle was -24.6. Conclusion: A correct diagnostic strategy allowing a complete lesion assessment and an adapted therapeutic attitude can transform the prognosis of a traumatic lesion of the subaxial cervical spine.

1361

P555: Posterior Ligamentous Complex Reconstruction for Cervical Dislocation and Instability in Patients Without Vertebral Fracture with Artificial Ligaments: A Technical Note

Chengyi Huang ¹ , Beiyu Wang ¹ , Chen Ding ¹ , and Hao Liu ¹

¹ West China Hospital, Sichuan University, Orthopedics, Chengdu, China

Introduction: The posterior ligamentous complex (PLC) offers restraints to deformation in a complex and interconnected manner. The stability and range of motion (ROM) of the posterior cervical spine is greatly restricted when the PLC is damaged, even without bone disruptions. We describe a novel surgical technique, its advantages, and the postoperative condition of the first patient to use artificial ligament in a reconstruction surgery of PLC injuries in patients without lower cervical vertebral fracture. This technique aimed to fully retain the mobility of the injured segment based on spinal stability and apply dynamic reconstruction in patients’ treatment. Material and Methods: We present a detailed description of the reconstruction surgery including C4-6 artificial ligament reconstruction between spinous processes and C4-6 facet joint artificial ligament anchoring performed on C4-6 PLC injuries in a 27-year-old male presented with neck pain and restricted movement following a high fall injury accompanied by impaired movement of limbs. Results: Immediately postsurgery, the patient’s neck pain and quadriparesis had been improved. The spinal canal decompression and cervical spine sequence results were satisfactory, the facet joint face was in a good position, and the spinous process spacing returned to normal. After three months of rehabilitation, the patient reported improvement of symptoms and the physical and imaging examination showed a significant improvement in the patient’s condition. The patient’s neck mobility motor function had improved further. Conclusions: The present data demonstrate that the novel technique for reconstruction of PLC injury is feasible and safe. However, familiarity with cervical anatomy and adequate experience in lateral mass screws placement during surgery is crucial for this procedure. Therefore, a highly experienced cervical surgery team is recommended to perform the surgery.

1396

P556: Sequential Traumatic Cervical Fractures After Paragliding Accidents - Literature Review and Critical Analysis of a Case Report

Catarina Pereira ^1,2 , António Lemos Lopes ³ , and Ricardo Rodrigues-Pinto ^1,2

¹ Spinal Unit (UVM). Centro Hospitalar Universitário do Porto. Portugal, Orthopaedics, Porto, Portugal

² Instituto de Ciências Biomédicas Abel Salazar, Porto, Portugal

³ Centro Hospitalar de Trás-os-Montes e Alto Douro, Orthopaedics, Vila real, Portugal

Introduction: Sports-related cervical spine trauma is extremely common and may range from minor injuries to severe life-threatening fractures with spinal cord injuries. On-field assessment of these patients must be prompt and follow strict guidelines. Return to sport after (long) cervical spine fusion is controversial and may yield additional risks to the mobile segments of the cervical spine. Results: We present the case of a 52 year-old man who sustained C4-C5 and C6-C7 fracture-dislocations (ASIA-D) in a paragliding accident. A C5 corpectomy and C4-C6 anterior fusion was performed. Three years later he suffered another paragliding accident, which caused a C6-C7 fracture-dislocation. A C6-C7 anterior fusion was performed, which failed one month later. Ultimately, he was treated with 360º fusion in a 2-stage procedure. Two years after this procedure, the patient sustained a car accident, which caused an odontoid fracture. Conclusion: Unstable spinal fractures require surgical fixation to prevent neurological injury. Long cervical fusions place the adjacent levels in higher stresses, making them prone to further injury. Treatment of these complex and sequential injuries represents a challenge for spinal surgeons.

1495

P557: Post-Traumatic Cervical Spine Injury Without Radiological Abnormality in Adults: A Case Report

Ines Cherif ¹ , Fatma Kolsi ¹ , Omar Hattab ¹ , Firas Jarraya ¹ , Brahim Kammoun ¹ , and Boudawara Mohamed Zaher ¹

¹ Habib Bourguiba University Hospital, Department of Neurosurgery, Sfax, Tunisia

Introduction: Spinal cord injury (SCI) after blunt spine trauma is located in the cervical spine in approximately two-thirds of cases. Most often, cervical SCI is caused by fracture or subluxation, which is easily diagnosed by normal plain radiographs or computed tomography (CT) scans. However, SCI may also occur in absence of bony abnormality which is defined as the occurrence of acute traumatic myelopathy despite normal plain radiographs and normal CT studies. Though common in children compared to adults, overall incidence is less. We report here a case of a 27-years old patient with post traumatic cervical spine injury without radiological abnormality. Case report: Our case is about a patient who sustained a cranio-cervical injury after a road accident. The patient presented also initial unconsciousness without vomiting. The neurological exam showed cervical rigidity with neck pain and spastic quadriparesis. The cervical CT scan was normal and the MRI showed spine contusion from C3 to C5. The treatment consisted on corticoide with regularly follow up and cervical immobilisation leading to good clinical improvement. Conclusion: In adult patients experiencing cervical spine injury without radiological abnormality, MRI is a diagnostic tool with important prognostic value. In fact, the extent of lesion is a powerful predictor of clinical outcome, being associated with both neurologic condition and recovery.

1497

P558: Traumatic Atlantoaxial Dislocation With Odontoid Fracture: A Case Report

Ines Cherif ¹ , Fatma Kolsi ¹ , Omar Hattab ¹ , Firas Jarraya ¹ , Brahim Kammoun ¹ , and Boudawara Mohamed Zaher ¹

¹ Habib Bourguiba University Hospital, Department of Neurosurgery, Sfax, Tunisia

Introduction: The combination of atlantoaxial joint dislocation and odontoid process fracture is a rare spine injury. The estimated frequency is less than 2% among upper cervical spine injuries. This injury combination is serious because of the resulting instability. Materials and Methods: We are reporting on the one-year follow-up a case that occurred in the context of a high-energy head injury. Radiological findings and treatment modalities are also discussed. Results: A 29 years-old patient was admitted in our department after a road accident. The neurological exam found a stiff head posture rotated to the right. However, there was no other neurological problems. On cervical spine X-rays and CT scan, there was a rotational atlantoaxial dislocation type 1 based on Fielding classification, with a right articular facet fracture of the odontoide. The cervical MRI showed an extra-dural hematoma in front of C1-C2 with no compression and integrity of the transverse ligament. Conservative treatment consisted of axial traction with a head tong to attempt to reduce the atlantoaxial dislocation. Despite a progressive increase in weight the joint was only partially reduced. We attempt gentle closed manipulation under scopic control. The radiological control after manipulation showed that the C1-C2 joint was reduced. The cervical spine was immobilized later using an integral neck brace during 3 months. At the one-year follow-up, the clinical picture was stable and X-rays was satisfying. The patient had no major functional problems and dynamic X-rays showed good range of motion in flexion, extension and rotation. Conclusion: The combination of atlantoaxial joint dislocation and odontoid process fracture is a rare injury. A closed reduction of the dislocation must be attempted. Once the dislocation is treated, treatment of the odontoid fracture is determined based on its reduction and stabilisation (conservative treatment or direct screw fixation). If the reduction fails, an open reduction must be performed through a posterior approach. However the conservative treatment may be a good alternative in case of integrity of the transverse ligament and without C1 C2 instability.

1499

P559: Upper Cervical Spine Trauma: An Institutional Experience

Fatma Kolsi ¹ , Ines Cherif ¹ , Omar Hattab ¹ , Firas Jarraya ¹ , Brahim Kammoun ¹ , and Boudawara Mohamed Zaher ¹

¹ Habib Bourguiba University Hospital, Department of Neurosurgery, Sfax, Tunisia

Introduction: Traumatic injuries of the upper cervical spine are often encountered, and may be associated to severe neurological outcome. Thus, full characterization of the injuries requires an accurate history and physical examination, and management requires an in-depth understanding of the radiographic projection for timely diagnosis and stabilization of patients with upper cervical spine injuries. Materials and Methods: This is a retrospective study of 66 patients with upper cervical spine injuries managed at the neurosurgical department in Habib Bourguiba hospital at Sfax between 2005 and 2015. Results: 66 cases were included in the study. The age range from 3 to 80 years (mean age = 39.6). The sex ratio (M/F) was 5. Road accidents were the most frequent cause (75.75%). Clinically, cervical spine syndrome was found in 90.9% of cases, neurological deficit was present in 9 cases (13%). A lower cervical spine injury was associated in 19 cases (28.78%) and cranial trauma was found in 43 cases (65.15%). Radiological analysis included standard X-ray and CT scan with Multiplanar reconstruction in all patients. MRI was performed in 10 cases. We found 72 lesions: C1-C2 dislocation in 6 cases; C1 fracture in 18 cases; C2 fracture in 48 cases including 25 odontoid fractures. Orthopedic treatment was performed in 45 cases of stable fractures. 21 patients were operated. Posterior approach including hooks and rods was performed in 9 patients, wiring in 1 case, and 3 transarticular screw fixation. In 8 cases anterior approach was performed: 2 odontoid screwing and 6 cases of C2-C3 discectomy with bone graft. The follow-up ranged from 6 to 38 months. We found a neurological improvement in the 9 cases with initial deficit. Conclusion: The upper cervical spine is a common site of trauma, and given its unique anatomy and biomechanics, understanding the specifics of a particular injury, leading to the derivation of an appropriate management strategy, can often be complex and nuanced. Clinico-radiological analysis of upper cervical spine injuries leads to better therapeutic indications and improves long-term outcome in terms of spine stability and biomechanics.

1508

P560: Management of Type II Odontoid Fracture Associated With Cervical Fracture-Dislocation - 2 Case Reports

Sara Diniz ^1,2 , João Soares do Vale ^1,2 , Manuel Carrapatoso ^1,2 , Catarina Pereira ^1,2 , and Ricardo Rodrigues-Pinto ^1,2

¹ Centro Hospitalar Universitário do Porto. Portugal, Spinal Unit, Department of Orthopaedics, Porto, Portugal

² Instituto de Ciências Biomedicas Abel Salazar, Porto, Portugal

Introduction: Odontoid fractures are the most common injury of the cervical spine. In young patients, they are typically the result of high-energy trauma, whereby it can be associated with other findings. The authors present two case reports of type II odontoid fractures associated with C5-C6 fracture-dislocation in two young adults. Material and Methods: A 32-year-old man patient presented to the emergency department after a fall from a height of 4 meters. He was neurologically intact (ASIA E). The RX and CT showed a C5-C6 fracture with left facet dislocation and a type II odontoid fracture. Patient was submitted to a posterior cervical C4-C7 fusion and a C1-C2 transarticular fixation with two cannulated screws (Magerl Technique). A 40-year-old man sustained a moderate-energy car accident and presented to the emergency department with a C5-C6 bilateral facet dislocation and a type II odontoid fracture. The patient had radiating neck pain to the left arm, thumb and index finger and associated paresthesia (ASIA D). He was submitted to a posterior reduction and C5-C6 lateral mass fixation followed by an anterior odontoid fixation with a cannulated screw in a different time surgery. Results: Both patients were placed in a collar for 8 week. The second patient recovered from the neurologic deficits. 1 year after surgery both demonstrate solid C5-C6 fusion and odontoid union. The first patient will be scheduled for C1-C2 implant removal. Conclusion: These cases depict rare simultaneous fractures of the cervical spine and different approaches. In both cases a posterior surgery was used to address the C5-C6 fracture-dislocation but while in the first a C1-C2 fixation was used to treat the odontoid fracture, in the second, an anterior osteosyntheses was performed. The decision between both approaches should be directed by fracture and patient characteristics, implant availability and surgeon preference.

1611

P561: Tunisian Experience With the Upper Cervical Spine Injury

Yassine Gdoura ¹ , Anis Abdelhedi ¹ , Mohamed Znazen ¹ , Ahmed Maatoug ¹ , and Boudawara Mohamed Zaher ¹

¹ Habib Bourguiba Hospital, Neurosurgery, Sfax, Tunisia

Introduction: The upper cervical spine trauma is a frequent pathology related to the upsurge of road traffic accidents and especially falls. These lesions are often serious, but emergency neurological complications are rare. Untreated upper cervical spine lesions threaten the patient's life with minimal subsequent trauma. We aimed to specify the epidemiological, clinico-radiological, therapeutic and evolutionary characteristics of the studied population in order to propose a practical decision tree and a therapeutic scheme for the management of trauma of the upper cervical spine based on a review of the literature. Material and Methods: A retrospective study of 66 exploitable upper cervical spine trauma files collected at the neurosurgery department of Habib Bourguiba hospital in Sfax between January 2005 and December 2015. Results: The series includes 55 men (83.3%) and 11 women (16.6%) ranging from 3 to 80 years old with an average age of 39,6. We found 50 road traffic accidents (75.75%), 16 falls (24.25%). Forty-nine patients were admitted within hours of the trauma (74.24%). A cervical spinal syndrome of variable intensity was found in 60 patients (90.9%), an incomplete sensory and / or motor deficit in 9 patients (13%). The associated lesions are mainly represented by cranial traumas which were found in 43 injured (65.15%) and trauma to the lower cervical spine in 19 patients (28.78%). All patients underwent standard radiography and computed tomography. Magnetic resonance imaging has been performed in 10 patients (15.15%). over the 72 lesions, we found 6 C1-C2 dislocations (8.34%), 18 atlas fractures (25%), 48 fractures of the axis (66.66%) including 25 fractures of the odontoid (34.7%). Exclusive orthopedic treatment was performed for lesions considered stable in 45 patients (68.18%). Twenty-one patients were able to benefit from surgical treatment (31.81%). Thirteen posterior approaches (61.9%) were thus made with placement of hooks and rods in 9 patients, cervico-occipital assembly in 3 cases and lacing in 1 case. In 8 cases, the approach was anterior (38.1%), allowing 2 screw connections of the odontoid and 6 C2-C3 discectomies with placement of a bone graft (57.1%). The postoperative results were satisfactory for almost all of the patients. The evolutionary follow-up was 6 to 38 months and was marked by a clear regression of the initial sensory-motor deficit in the 9 patients. Conclusion: Injuries to the upper cervical spine are rarely associated with neurological disorders in the injured we receive. They are life-threatening because of the risk of secondary displacement and the advanced age of the majority of patients. The most common fractures are Jefferson's fractures, hangman's fractures, odontoid fractures. Their management requires a thorough understanding of the lesion and the potential instability. Thus, each lesion must be analyzed in order to offer the patient the fairest benefit / risk balance. The therapist's experience is a major decision-maker.

1733

P562: Posterior Reduction and Osteosynthesis of an Unstable C1 Fracture With Monoaxial Lateral Mass Screws

Joana Tavares ¹ , António Cuco ¹ , Carla Reizinho ¹ , and Ana Luís ¹

¹ Hospital Egas Moniz – Centro Hospitalar Lisboa Ocidental, Neurosurgery department, Lisboa, Portugal

Introduction: Surgical treatment of unstable atlas fractures has evolved to motion-preservation techniques, namely, isolated C1 osteosynthesis - open reduction and internal fixation (ORIF-C1). However, regardless of transoral or posterior approach, the reduction is frequently unsatisfactory. To overcome lack of reduction, allowing for ring osteosynthesis, it has been recently proposed the use of monoaxial lateral mass screws in association with reduction devices. Materials and Methods: The authors report the use of this technique on a patient with an isolated atlas fracture. Results: We report the case of an 85-year-old man, admitted to our hospital after a bed fall. The only complain was neck pain and neurological examination was normal. CT scan showed an isolated atlas fracture - Jefferson type III, Landells and Van Peteghem type II, Gehweiler type 3b, Dickman’s type I, with an hang over of the left C1 lateral mass of 9 mm. Angio-CT excluded lesions of the vertebral arteries. Surgical treatment was adopted. Monoaxial cannulated lateral mass screws were inserted with reduction extenders attached and a slightly kyphotic rod was used to connect the screws. To achieve posterior reduction of the left lateral mass, slight compression was applied to the proximal part of the extenders. To obtain reduction of the anterior part of the lateral mass, controlled distraction was applied to the distal part of the reduction extenders, attached to the monoaxial screws. Conclusion: The variation of the classic posterior ORIF-C1 technique used in this case, recurring to monoaxial screws and a reduction system, represent a preferable approach in cases where the displacement of the fracture mandates for ventral and dorsal reduction.

1739

P563: Craniocervical Fixation With Occipital Condyle Screws - Case Report

Joana Tavares ¹ , António Barata ¹ , Tiago Lorga ² , Carla Reizinho ¹ , Luís Marques ¹ , and Ana Luís ¹

¹ Hospital Egas Moniz - Centro Hospitalar Lisboa Occidental, Neurosurgery, Lisbon, Portugal

² Hospital Egas Moniz - Centro Hospitalar Lisboa Occidental, Neuroradiology, Lisbon, Portugal

Introduction: The cranio-vertebral junction fixation is challenging due to its complex anatomy and the presence of important anatomical structures. Occipitocervical fusion is indicated in various pathological conditions that may cause instability in this area. The most popular method of occipital inclusion, implies the application of a plate with screws at occipital squama. However, it involves an extensive dissection of soft tissues and it is not feasible in certain scenarios like on patients with previous posterior fossa craniectomy. La Marca described a technique using the occipital condyles as a sole anchor point for cranial fixation, in substitution of occipital squama fixation. It was later described by Uribe with good clinical outcomes and biomechanical equivalence. Materials and Methods: The authors report the use of this technique in a craniocervical fusion surgery on a patient with cervical myelopathy due to compression and C0-C1 and C1-C2 instability. Results: We describe the case of a 77-year-old man with a known 1-year history of cervical myelopathy symptoms with sudden worsening (Nurick grade 3, Ranawat grade IIIA). At neurological exam it was found a right side hemiparesis (grade 3-4/5 with brachial predominance), Lhermitte and Hoffmann’s sign, hyperreflexia in the upper limbs, proprioception impairment and hypoesthesia of the right limbs and hemi-trunk. Imaging study with MRI showed synovial hypertrophy and enlargement of the C1-C2 space, periodontoidal inflammatory pannus with severe medullary bulb compression and C1-C2 axial dislocation, indicative of C0-C1-C2 instability. At the preoperative planning, the volume of the occipital condyles, the path of the hypoglossal canal, the configuration of the posterior fossa and the relationship between the entry point and the posterior condylar emissary vein and vertebral arteries were analyzed, concluding that the technique was feasible. The patient underwent posterior fixation C0 (occipital condyles), C1 (lateral masses) and C2 (pedicles), osteotomy of the posterior arch of C1 and laminectomy C3-C7 for complementary subaxial decompression. Adequate bulb-medullary decompression and correction of C1-C2 axial dislocation were achieved. After a 10-month follow-up, there was significant clinical improvement (Nurick grade 1, Ranawat II), with no apparent failure of the fixation. Conclusions: Occipito-cervical correction with the occipital condyles screws technique can be used safely and effectively. Its inclusion in the technical arsenal of the spine surgeon allows to add versatility, especially in cases where it is necessary to decompress the posterior fossa or when variations in the anatomy of the posterior fossa make it difficult to perform a construction with an occipital plate. It is also a muscle-sparing approach, as it limits the muscle dissection of the occiput needed.

1805

P564: Analysis of morbidity und mortality rate in nonagenarinans undergoing atlanto-axial fusion for acute traumatic odontoid type II fractures: 9-74 months follow-up

Basem Ishak ¹ , Mohammed Issa ¹ , Andreas W. Unterberg ¹ , and Karl L. Kiening ¹

¹ Heidelberg University Hospital, Department of Neurosurgery, Heidelberg, Germany

Introduction: Odontoid type II fractures are the most common cervical spine injuries in patients over 75 years. The decision for surgical treatment in patients over 90 years of age is still controversial due to a high complication rate. The aim of this study was to assess morbidity, mortality and clinical outcome in nonagenarians undergoing CT-guided atlanto-axial posterior instrumentation. Material and Methods: A total of 15 patients with an acute traumatic odontoid type II fracture who underwent CT-guided atlanto-axial stabilization were retrospectively analyzed. Complications, morbidity and mortality rate, as well as length of ICU and hospital stay were determined. A clinical follow-up (FU) of 9 - 74 months was given (mean FU: 36.1 months). Results: Mean age was 91.4 years (range 90-96 y). In-hospital mortality was 0%. Five patients died during the follow-up period. Average length of hospital stay was 13.4 days and 1.9 days for ICU. Blood transfusion was necessary in three patients (20%). Two patients (13%) developed urinary tract infection and one patient (7%) developed a Delirium. One patient (7%) developed sepsis with full recovery within several weeks. Implant-related complications occurred in one patient (7%). Conclusion: Our current study confirms that atlanto-axial stabilization in nonagenarians is a safe and effective procedure with few complications. Our results revealed that atlanto-axial stabilization in nonagenarians does not negatively impact survival.

1950

P565: Split Atlas: A Rare Cause of Cervical Myelopathy

Khalil Habboubi ¹ , Hassen Makhlouf ¹ , Meddeb Mehdi ¹ , Sliti Firas ¹ , Bouhdiba Saber ¹ , and Mondher Mestiri ¹

¹ Kassab Institute, Tunis, Tunisia

Introduction: The occipitocervical junction (OCJ) is a complex anatomical area that includes several vital structures and allows the transition between the central nervous system and the axial skeleton. Many types of bone and/or nerve malformations, major or minor, have been described but remain rare. We report the case of a patient with a rare “benign” congenital malformation of the OCJ associated with neurological disorders. Case Presentation: A previously healthy, 18-year-old male patient, presented with a 6-month history of paresthesia of both arms and legs, cervical pain, and walking difficulty after a minor neck trauma. His symptomatology was improving gradually, but there was no bowel or bladder dysfunction. At the time of admission, physical examination revealed a walk with mowing on the right side, pain on palpation of the upper cervical spine, contracture of the paravertebral muscles and limited cervical range of motion. Neurological assessment revealed quadri-pyramidal syndrome with bilateral upper and lower limbs hyperreflexia, bilateral Babinski sign and Hoffman’s reflex present. Motor function and sensory examination were normal in the left upper limb and lower limbs. In the right upper extremity, motor function was rated three-four out of five, with hypoesthesia in the C7-C8 territory. Furthermore, examination of the perineal area was unremarkable. Plain radiographs were without abnormalities. A computed tomography (CT) scan complement revealed partial aplasia of the anterior and posterior arches of the C1 vertebra resulting in a split atlas, associated with a platybasia and basilar impression. Magnetic resonance imaging (MRI) showed cord compression at the atlas ring and intramedullary high T2 signal intensity area. We decided to perform surgical decompressive laminectomy and occipitocervical fusion by a posterior approach because the patient had neurological symptoms. We discovered during surgery that bony defect in the posterior arch of C1 was replaced by a connective tissue cord compressing the dural sheath. Our patient underwent laminectomy of C1, enlargement of the foramen magnum, occipito-cervical fixation and posterior grafting at the expense of the posterior iliac crest. The patient’s symptoms recovered completely one month after surgery and the arthrodesis was consolidated at four months. Conclusion: Malformations of the OCJ are morphological abnormalities leading to polymorphic symptomatology and may be responsible for serious neurological disorders. A good knowledge of the split atlas is necessary in order not to misdiagnose a fracture, dislocation or osteolysis.

Trauma—Thoracolumbar

71

P566: Postoperative Complications of Thoracolumbar Fractures in Multiple Trauma Patients According to the Surgical Timing

Guillermo Ricciardi ¹ , Ignacio Gabriel Garfinkel ¹ , Gabriel Genaro Carrioli ¹ , and Daniel Oscar Ricciardi ¹

¹ Centro Médico Integral Fitz Roy, Orthopaedics and Traumatology, Buenos Aires, Argentina

Introduction: the objective is to compare the rate of complications in the immediate postoperative period of vertebral fractures in patients with associated traumatic injuries operated before or after 72 hours after the trauma in our center. As a secondary objective, to estimate the variables that were associated with the surgical timing before and after 72 hours in our series. Materials and Methods: retrospective observational analytical study of a series of patients treated surgically for vertebral fractures due to high energy trauma with significant associated injuries in other regions. Operated in our institution, an occupational trauma referral center, by the same surgical team and during the period between January 2013 and December 2019. Results: 40 patients were included (39 men and 1 woman), the association of the surgical timing (before and after 72 hours) with the number of complications was not significant (P.827). There were statistically significant differences between both groups in the variables age, systolic blood pressure, initial SOFA score and presence of neurological injury (P.014, P.029, P.032 and P.012). The surgical delay was correlated with the SOFA score (P.007). Conclusion: surgical intervention before and after 72 hours did not show significant differences in the number of complications. Early surgery did not associate a greater physiological impact in the immediate postoperative period. Early intervention patients were significantly associated with younger ages, higher blood pressure values, less physiological damage, and coexistence of neurological damage. Surgical delay was positively correlated with the initial SOFA score.

Keywords

“thoracolumbar fractures”, “multiple trauma”, “complications”, “surgical timing”.

Level of evidence: III

115

P567: Clinical and Radiological Outcome of Flipped Reposition Laminoplasty Technique for Decompression of Spinal Cord in Traumatic Fractures of Thoracic and Lumbar Spine - A Series of 80 Patients With Neurological Deficits

Shaffaf Kareem ^1,2

¹ Vardhman Mahavir Medical College and Safdarjung Hospital New Delhi, Spine Care Unit, New Delhi, India

² Manipal Hospitals HAL Airport Road Bangalore, Spine Care Department, Bengaluru, India

Introduction: Flipped Reposition Laminoplasty (FRL) is a technique wherein the laminar flap is lifted leaving the cranial part attached to the intact posterior ligamentous complex, flipped cranially for spinal canal exposure and then repositioned back to its original place after adequate cord decompression. The aim of the study is to find the clinical and radiological outcome of FRL in spinal cord decompression of thoracic and lumbar spinal injury patients with neurological deficit. Material and Methods: A prospective interventional study was done after attaining approval from Institute’s Ethical Committee. All patients aged ≥18 years diagnosed clinico-radiologically to have traumatic thoracic or lumbar fracture with neurological deficit underwent FRL method for decompression along with appropriate pedicle-screw instrumentation. Those with intact neurology, pathological fractures, congenital spinal anomaly, or severe deformity were excluded from the study. Outcome assessment was done during their regular follow-up. Results: Average follow-up was of 22 months. Mean age of the study population was 30 years with male preponderance. Fall from height was the most common mode of injury. Mean operation time and blood loss was 115minutes and 400ml, respectively. Neurological improvement of at-least 1 grade was seen in all incomplete neurology patients. No patients showed deterioration of neurology. A statistically significant 70% reduction in spinal canal encroachment was noted. Lateral Cobb’s angle decreased from a mean of 31.8° to 15.2° 1-year post-operatively. None had post-operative complications like scar formation, spinal-instability, migration of cut lamina or progression of deformity. Evidence of fusion of cut lamina was seen in 87.5%. Conclusions: FRL method provides adequate space for spinal cord decompression along with maintaining posterior spinal integrity. This is a safe and effective alternative to prevent complications associated with laminectomy in thoracolumbar spine injuries.

123

P568: Investigation of Thoracolumbar Fractures in Patients With Psychological Disorders Using an Injury Severity Score

Takeshi Sasagawa ¹

¹ Toyama Prefectural Central Hospital, Toyama City, Japan

Introduction: Thoracolumbar fractures due to high-energy trauma occur frequently in patients with psychological disorders. We sought to investigate features of thoracolumbar fractures in patients in Japan with psychological disorders using an Injury Severity Score, for which, to our knowledge, there is no report to date. Materials and Methods: The present study included 111 patients who were hospitalized for treatment of thoracolumbar fractures due to high-energy trauma between March 2009 and March 2019. Inclusion criteria were patients who were aged ≦65 years at the time of the trauma. Exclusion criteria included osteoporotic fracture, and minor fracture (AO type A0). We investigated age, sex, injury mechanism, injury level, psychological disorder, Injury Severity Score (ISS), Abbreviated Injury Scale (AIS) of injured vertebra, treatment (surgery or not), and timing of surgery. Results: Twenty-six of the 111 patients (23%) had psychological disorders. Eight patients had schizophrenia, 7 had adjustment disorders, 5 had depression, 5 had alcohol or drug dependences, and 1 had epilepsy. We divided the patients into 2 groups: P group (n = 26) patients who have psychological disorders and N group (n = 85) patients who do not have psychological disorders. The P group patients were significantly younger than N group patients. There were no differences in sex between the groups. P group patients injured themselves significantly more frequently by jumping (85%) compared with N group patients. The ratio of severe trauma (ISS≧16) in the P group patients (50%) was significantly higher than that in N group patients (11%). Furthermore, in patients with severely injured vertebra (AIS ≧ 3), the ratio of severe trauma (ISS≧16) in the P group patients (55%) was significantly higher than that in the N group patients (15%). By contrast, in patients with mildly injured vertebra (AIS = 2), there was no significant difference in the ratio of severe trauma between the 2 groups. There were no significant differences in the location of injured vertebra, treatment, and timing of surgery. Conclusion: The P group patients were, significantly younger, jumped more frequently, and had a higher severe trauma than N group patients. In patients with severely injured vertebra, the ratio of severe trauma in P group patients was significantly higher than that of N group patients. Therefore, it is important to make decisions for treatment of thoracolumbar fractures in patients with psychological disorders based on a concept of Spine Damage Control.

124

P569: Optimal Timing of Minimally Invasive Spine Stabilization Using Percutaneous Pedicle Screws in Patients With Thoracolumbar Fracture

Takeshi Sasagawa ¹

¹ Toyama Prefectural Central Hospital, Toyama City, Japan

Introduction: The optimal timing of stabilization in patients with traumatic thoracolumbar fracture remains controversial. The use of percutaneous pedicle screws for posterior spinal stabilization has been established and multiple studies suggest that this procedure is safe and minimally invasive for many spinal disorders. The aim of this study is to determine the optimal timing of minimally invasive spine stabilization using percutaneous pedicle screws in patients with thoracolumbar trauma. Materials and Methods: The present study included 27 patients who underwent posterior spinal stabilization using percutaneous pedicle screws for traumatic thoracolumbar fractures between February 2013 and July 2017. Exclusion criteria included osteoporotic fracture, dislocation fracture and patients with severe paralysis. We divided the patients into an early group (n = 14) in whom surgery was performed within 3 days of fracture and a late group (n = 13) in whom surgery was performed more than 3 days after fracture. We assessed the demographics of patients (age, sex, number and location of injured vertebra, mechanism of injury, and coexisting injury), surgical data (range of stabilization, operative time, intraoperative blood loss, and postoperative complication), and hospital length of stay (HLOS). Exclusion criteria for assessment of HLOS included patients with coexisting injury affecting HLOS such as head injury, fractures of lower extremities requiring non-weight bearing recovery, and patients who underwent additional anterior spinal stabilization. We identified 14 patients (early group 8, late group 6) for assessment of HLOS. Results: There were no significant differences in age, sex, number and location of injured vertebra, mechanism of injury, coexisting injury, range of stabilization, operative time, and intraoperative blood loss between the early and late groups. In the early group, no patient had postoperative complications, whereas in the late group postoperative complications were observed in 2 patients (urinary tract infection and cholecystitis, respectively). HLOS of the early group (10.8 ± 5.9 days) was significantly shorter than that of the late group (17.3 ± 3.9 days) (P < .05). Conclusion: With minimally invasive posterior spine stabilization using percutaneous pedicle screws for thoracolumbar fracture, there were no differences in postoperative blood loss between patients with early and late treatment and no postoperative complications in the early group. Given HLOS of patients in the early group was significantly shorter than that of patients in the late group, early surgery for thoracolumbar fracture is considered optimal.

125

P570: Return to work in patients with thoracolumbar spinal injuries due to high-energy trauma

Takeshi Sasagawa ¹

¹ Toyama Prefectural Central Hospital, Toyama City, Japan

Introduction: High-energy trauma occurs most commonly in working age individuals. Returning to work is an important theme for these individuals from the viewpoint of economic stability and social standing. The aim of this study was to investigate the return to work of patients in Japan with thoracolumbar spinal injuries due to high-energy trauma, for which, to our knowledge, there is no report to date. Materials and Methods: The present study included 54 patients who underwent surgical spinal stabilization for. thoracolumbar fractures due to high-energy trauma. Inclusion criteria were patients who were employed and aged 20-65 years at the time of the trauma. The postoperative period was 1-5 years at the point of investigation. We investigated age, sex, employment status, occupation, adaptation of workers’ compensation insurance, injury mechanism, injury level, facet interlocking, psychological disorder, degree of paralysis (ASIA), surgical approach, persistent back pain, and removal of instrumentation or not. Based on their return to work status, patients were divided into return to work (RTW) and nonreturn to work (non-RTW) groups. The RTW group was further divided into a complete RTW (co-RTW) group including those who had returned to the same work and a changed RTW (ch-RTW) group including those who had returned to work, but changed job specification or occupation. Results: Forty-eight of 54 patients (89%) had returned to work. There were 35 patients in the co-RTW group and 13 in the ch-RTW group. In the non-RTW group, reasons for not returning to work were severe paralysis (4 patients, all 4 had thoracic injury, and 3 of 4 had facet interlocking) and advanced age (2 patients, aged 64 and 62 years).Those in the non-RTW group (n = 6) had significantly more severe paralysis, thoracic injury and facet interlocking that was not related to the other items, and greater age than those in the RTW group (n = 48)(P < .05). In the ch-RTW group (n = 13), 8 of 13 patients complained that persistent back pain was the reason changing job specification or occupation. Those in the ch-RTW group had a significantly higher frequency of persistent back pain (P < .05) that was not related to the other items than those in the co-RTW group. Conclusion: The proportion of those returning to work after thoracolumbar spinal injuries due to high-energy trauma was 89%. The reasons for not returning to work were severe paralysis and advanced age. The main reason for changing job specification or occupation was persistent back pain.

126

P571: Factors Associated With Persistent Back Pain After Thoracolumbar Junction Fracture in Workers

Takeshi Sasagawa ¹

¹ Toyama Prefectural Central Hospital, Toyama City, Japan

Introduction: High-energy trauma occurs most commonly in working age individuals. Returning to work is important for these individuals or their economic stability and social standing. A major reason for changing job specification or occupation is persistent back pain. We sought to investigate the factors associated with persistent back pain in workers after thoracolumbar junction fracture. Materials and Methods: We included 32 patients who underwent surgical spinal stabilization for 1 level thoracolumbar junction (T11-L2) fractures without facet interlocking. Inclusion criteria were employed patients aged 20–65 years at the time of the trauma. The postoperative period was 1–3 years at the point of investigation. We investigated persistent back pain, on a Numerical Rating Scale (NRS), Oswestry Disability Index (ODI), age, sex, injury mechanism, injury level, initial and final local kyphosis angle, degree of paralysis (ASIA), initial value of creatine kinase, coexisting injury, surgical approach, use of percutaneous pedicle screws, removal of instrumentation or not, employment status, occupation, adaptation of workers’ compensation insurance, psychological disorder, and return to work status. Patients were divided into groups of those with back pain (BP) and those without. Each item was examined to determine whether there is a significant difference between the two groups. To identify the factors associated with BP in patients after thoracolumbar junction fracture, multiple logistic regression analysis was conducted in which the presence or absence of BP was a dependent variable, and items that were significantly different between the two groups were independent variables. Results: There were 15 patients in the group with BP group and 17 in the group without. NRS and ODI in the group with BP were 2.4 ± 2.0 and 16.2 ± 14.0, respectively. Those in the group with BP had significantly more severe final local kyphosis, and higher frequency of regular employment, adaptation of workers’ compensation insurance, and changing occupation than those in the group without BP. There was no difference in the other items between the groups. In multiple logistic regression analysis to identify factors associated with BP, adaptation of workers’ compensation insurance, and severe final local kyphosis were independently associated. The odds ratio for adaptation of workers’ compensation insurance was 16.15 (95% confidence interval [CI], 1.63–160.34), and final local kyphosis was 1.22 (95% CI, 1.04–1.44). Conclusion: The adaptation of workers’ compensation insurance, and severe final local kyphosis are independently associated with persistent back pain in workers after thoracolumbar junction fracture.

261

P572: The Effect of Cement Volume on the Risk of Adjacent Fractures - Does Volume Matter?

Oliver Riesenbeck ¹ , Niklas Czarnowski ¹ , Michael Raschke ¹ , and René Hartensuer ¹

¹ University of Muenster, Department of Trauma-, Hand- and Reconstructive Surgery, Muenster, Germany

Introduction: Concerning the volume of cement used in kyphoplasty, there are different opinions. On the one hand, there should be an influence on the analgesia and the reduced risk of a new fracture of the treated vertebral body. On the other hand, there is a controverse discussed suspicion of increased adjacent fracture rates. This biomechanical study on multisegmental human spinal samples investigates the impact of cementum volume after kyphoplasty on the adjacent segments for the appearance of adjacent fractures. Materials and Methods: In 13 osteoporotic multisegmental spine samples (Th11 - L3) an incomplete burst fracture in LWK 1 was induced in a standardized manner. The erection after kyphoplasty was performed under lateral X-ray control. The amount of cement used, the erection of the vertebral body and the balloon filling volume were documented. After curing of the cement, a cyclic load test was carried out in 20 stages with linearly increasing axial load (maximum load of the final stage 1.3 kN). One stage consisted of 500 cycles. After each step a radiological control was performed. Results: The reconstruction of the vertebral body by means of balloon kyphoplasty led to a reconstruction of the vertebral body height anterior +12%, middle +11% and posterior 3%. However, a loss of height remained in comparison to the intact vertebral body heights (anterior -10%, middle -12% and posterior -5%). The balloon was medially filled with 10 ml (Q1: 9, Q3: 12.25). The mean applied cement volume was 9.6 ml (Q1: 9, Q3: 12 ml). Under cyclic loading, there was an approximately linear negative correlation between the volume of cement used and the load and time required to induce adherence pathology. Conclusion: In the used biomechanical model a clinically comparable reconstruction of the vertebral body could be achieved after experimentally generated vertebral body fractures. The published positive effects of an increased cement volume with respect to analgesia and stabilization of the fractured vertebral body are supplemented in the present work on a possible negative effect on the occurrence of adjacent fractures.

337

P573: Kyphotic Correction of Neglected Thoracic Spine Fracture-Dislocation Using Posterior Column Osteotomy

Torphong Bunmaprasert ¹ , Nattharut Chaibhuddanugul ² , Jakkrit Keeratiruangrong ² , Raphi Raphitphan ² , and Nantawit Sugandhavesa ²

¹ Chiang Mai University, Orthopaedics, Chiang Mai, Thailand

¹ Chiang Mai University, Orthopaedics, Chiang Mai, Thailand

Introduction: Thoracic spine fracture-dislocation without neurological deficit is rare. If occurs, it may lead to severe pain, deformity and progressive disability. Rigid spinal stabilization is necessary for fracture stabilization. Furthermore, additional spinal osteotomies are required to correct the complex neglected, delayed trauma. Objective is to demonstrate the surgical techniques using to correct kyphotic deformity in patient with neglected thoracic trauma. Material and Methods: A 23-year-old woman sustained motor vehicle injury for 2 months. She developed spastic gait, severe back pain, kyphoscoliotic deformity and progressive bilateral lower extremity weakness. Radiographic study showed severely-displaced coronal fracture of T8-T9 vertebrae with massive joint dislocation. Sagittal Cobb’s angle was measured as 65°, C7 SVA as 8 centimeters and spinal shortening of 8 centimeters. Minimal callus formation was observed. Spinal canal was relatively widened due to fracture comminution. Three posterior column osteotomies (PCO) at T7-8-9 were performed to correct semi-rigid kyphoscoliosis. Closure of the PCO’s was done by using pedicle screw fixation from T4-L1 under spinal navigations. Results: At least of 25° kyphotic correction was needed. Sagittal cobb’s angle was reduced from 65° to 25° (62% correction achieved). C7 SVA was corrected from 8 to 2 centimeters. Total body height was changed from 153 to 161 centimeters. No neurological deficit was found. Conclusion: In neglected, painful kyphoscoliotic thoracic fracture-dislocation; simple posterior column osteotomy (i.e. SPO) is safely used to correct the complex deformity and obviates the needs for aggressive harmful spinal osteotomies like PSO or VCR.

344

P574: Morcellised Local Grafts Are Cost Effective Alternative to Achieve Interbody Fusion in Thoracolumbar Fracture Dislocation: A Prospective Analysis of 53 Patients With 7 Years Follow Up

Santanu Kar ¹ and Kamran Farooque ¹

¹ JPNATC, AIIMS, Orthopaedics, New Delhi, India

Introduction: Traumatic fracture dislocation constitute less than 3% of thoracolumbar trauma and is a result of very high velocity injury. It is a three column injury that needs surgical intervention for a pain free stable spinal column. The present study evaluates the outcome of posterior decompression, 360⁰ fusion with use of local grafts and posterior instrumentation in 53 patients with follow up of seven years. Material and Methods: Between January 2010 to December 2013,64 patients was operated for fracture dislocation of thoracolumber spine,5 patients died during the course of follow up and six patients lost to follow up. Hence, 53 patient were included in the study. All the patients were operated with posterior approach –decompression, fixation along with interbody and posterolateral fusion with local graft obtained from resected posterior elements was performed. Long segment and short segment fixation construct with instrumentation at fractured level was perfomed in 28 cases and 22 cases respectively. Vertebrectomy was done in 2 patients. Patients were followed at 2,6 and 12 months and yearly thereafter. At each follow up, radiograph of dorsolumbar spine AP and lateral view was done. CT scan was done at 12 months post surgery to assess fusion status.ASIA scoring was done preoperatively and each follow up. After one year, patients were telephonically consulted and if needed asked to visit hospital. Results: There were 46 males and 7 were females. Mean age were 31.3 years (17-49). Mean follow up period was 7.4 yrs (range 7-10 yrs). Mean time from injury to surgery was 6.58 days (range 1-21 days). Thoracolumbar dislocation occurred mostly in thoracolumbar junction (T10-L2) in most (46) patients. 43 patients experienced combined anterolateral translation,5 each experienced lateral and posterior translation. Pre operatively, 36 pts were ASIA A,14 were ASIA B and 2 pts were ASIA C and one pt was ASIA E. Intraoperatively, dural tear was detected in 21 patients (all were ASIA A) (39.6%) and repaired accordingly. Among them only one patient improved neurologically by one grade. At one year, osseous fusion was noted in 48 (90.56%) patients and 5 patients (9.44%) had fibrous union.At the final institutional follow up at one year,34 pts were ASIA A,10 were ASIA B,5 were ASIA C,3 were ASIA D and one pt was ASIA E. One patient had undergone spontaneous decompression after trauma and had no neurological deficit before surgery. No implant failure were noted after 7 years of follow up. This strengthen the fact that morcellised bone grafts from resected posterior elements are sufficient to achieve fusion. This obviated the need of expensive modern metallic devices as well as autogenous iliac crest use for interbody fusion. Conclusion: 1. Long construct or short construct with fractured level instrumentation along with 360⁰ fusion is needed to achieve spinal stability. Local grafts are sufficient to achieve fusion. 2. Dural tear can be considered as a marker of irreversible spinal cord injury. 3. Most of the hospital visits after one year was not directly related to spine surgery but a consequences of paraplegia. Trophic ulcers, urinary and catheter related complications are the two most common causes of hospital visit after one year of surgery.

366

P575: High Prevalence of Osteoporotic Vertebral Fracture in Patients With Proximal emoral Fracture: A Matched Cases-Control Study

Kazushi Takayama ¹ , Teruo Kita ¹ , Norihiko Chiba ¹ , Hideki Sakanaka ¹ , and Yoshiki Yamano ¹

¹ Seikeikai Hospital, Orthopaedic Surgery, OSAKA, Japan

Introduction: Osteoporosis and associated fragility fractures are one of the most common causes of disability and a major contributor to medical care costs around the world. Proximal femoral fracture is common and one of the most serious fractures because of associated high morbidity and mortality. It is well recognized that a previous fracture increases the risk of subsequent fractures. The aim of this study was to determine whether the presence of vertebral fracture predicts subsequent proximal femoral fracture in a matched case-control study. Materials and Methods: This study was conducted with 1063 patients consecutively, aged seventy years and older who were admitted with proximal femoral fracture and underwent lumbar spine radiographs at our hospital from 2009 to 2017. Two hundred thirty one patients were male, and 832 were female. The mean age was 83.7 years (70-104 years). As for the types of hip fracture, 565 patients had femoral neck fractures, and 498 patients had trochanteric fractures. We evaluated the prevalence of vertebral fracture in lateral lumbar spine radiographs (Th11-L5), and the total number of fractures were calculated. In addition, these findings were compared with data randomly selected from the same number of age and sex- matched control patients almost all of who had low back pain but no previous history of proximal femoral fracture. Overall, 2126 patients were evaluated in this study. Results: One or more vertebral fractures were detected in 549 patients with proximal femoral fracture (51.6%; mean age, 84.7 years), which were more frequent in females (82 males; 35.4%, 467 females; 56.1%). The incidence of vertebral fracture was significantly higher in the patients with proximal femoral fracture than in the control group (51.6% vs 37.7%) and their odds ratio was 1.8. The mean number of vertebral fractures in the group with proximal femoral fracture (2.04 ± 1.3) was also higher than the value recorded for the control group (1.68 ± 1.0). As for the type of fracture, both the mean age and the incidence of vertebral fracture were higher in the patients with trochanteric fracture than in femoral neck fracture (85.2 years, 58.4% vs 82.3 years, 45.7%). There was a very strong positive correlation between the mean number of vertebral fractures and age in the control group, however there were just weak correlations of them in the patients with proximal femoral fracture. Conclusion: We found a higher prevalence of osteoporotic vertebral fractures in patients with proximal femoral fracture than age and sex- matched control. These results suggest that a previous osteoporotic vertebral fracture is associated with the risk of a subsequent proximal femoral fracture. The clinical implication is that patients older than 70 years presenting with a vertebral fracture require immediate attention to reduce reversible risk factors of a subsequent fracture.

452

P576: Anterior Reconstruction in Brust Fractures: Experience From a Level One Trauma Centre With 8 Years Follow Up

Santanu Kar ¹ , and Kamran Farooque ¹

¹ JPNATC, AIIMS, Orthopaedics, New Delhi, India

Introduction: Brust fractures account for 10-20 % of all thoracolumbar spine injuries. Surgical intervention is done when spinal instability is anticipated or there is worsening of neurological status. There are controversies regarding the use of anterior, posterior or combined surgical approach for brust fractures. Few surgeons advocates the use of anterior approach as it affords excellent visualization of the dura as well as meticulous decompression of the neural elements and anterior column reconstruction can be performed more precisely leading to more stable spinal column. The present study evaluate the outcome of anterior approach with an average follow up of 8 years. Material and Methods: 29 patients of thoracolumbar brust fracture who were operated with anterior approach from January 2009 to Dec 2012. 2 patients died and 4 patients lost to follow up. Hence 23 patients were included in the study. ASIA scoring was done preoperatively and each follow up. AP and lateral view of thoracolumbar spine was performed followed by CT scan and MRI. Cobbs method was used to measure kyphosis angle and percentage of canal compromise was determined with CT scan. All the cases was operated with anterior decompression, short segment fixation and anterior reconstruction with mesh cage.8 patients were operated within 48 hours of injury and rest 15 patients were operated after 7^th day but within 2 weeks of injury. Patients were followed at 2, 6 and 12 months. Pre and post operative VAS scrore was also determined. and radiographs were obtained. At 12 months CT scan was done to determine osseous fusion. Cobb’s angle was measured immedietly after surgery, at one year and at final follow up. Patients were contacted periodically over telephone and called to hospital for final follow up between 8-10 yrs. Results: There were 16 males and 7 females. Mean age was 28.48 ± 10.55 years (18-54 years). Mechanism of injury was fall from height in 12 cases, road traffic accidents in 11 cases.D12 vertebra was involved in 6, L1 in 16 and L2 was involved in one case. Pre operatively, 4 pts had ASIA A,5 were ASIA B,11 pts were ASIA C and 3 pt was ASIA D. Mean blood loss was 851.30 ± 172.66 ml, mean duration of surgery was 2.76 ± .35 hours and mean follow up period was 8.3 ± 0.9 years. Mean canal compromise was 53.56 ± 19.5 % preoperatively. Mean kyphosis angle preoperative, immediate postoperative, at one year and at 7 year follow up was 35.26 ± 9.40, 10.04 ± 3.05, 13 ± 2.80 and 14.30 ± 2.88. At one year osseous fusion was noted in all but one patient (osseous fusion rate 95.6%). Post operatively 2 were ASIA B and 6 pts were ASIA C,9 patients were ASIA D and 6 were ASIA E.20 patients (87%) improved their neurological grade by atleast one ASIA grade and three patients (13%) did not improve neurologically. Mean pre and post op VAS score was 8.3 and 1.81. There were no case of implant failure. Conclusion: Anterior reconstruction for brust fracture have special indications and merits. Anterior approach gives excellent result if canal compromise >50%, pre op kyphosis >30⁰,delay in surgery >7 days from trauma. Small cohort is major limitation of the study.

708

P577: Simplified Pedicle Substraction Osteotomy in Osteoporotic Vertebral Fractures

Nicolas Plais ¹ , Carlos Mengis ² , Jesus Manuel Gallego ² , Alejandro Peiro ³ , Felix Tome ⁴ , and Luis Alvarez Galovich ²

¹ Hospital Universitario San Cecilio de Granada, Unidad de Columna, Granada, Spain

² Hospital Universitario Fundación Jiménez Diaz, Madrid, Spain

³ Hospital San Joan de Deu, Barcelona, Spain

⁴ Hospital Universitario General de Villalba, Collado Villalba, Spain

Introduction: The treatment of osteoporotic vertebral fractures represents a formidable challenge. Although the majority can be treated conservatively, 30 % require surgery. In complex cases involving the presence of neurological symptoms, severe instability, sagittal malalignment or posttraumatic kyphosis, vertebral osteotomies may be necessary. In this study, we present technical variations of the classical pedicle subtraction osteotomy in order to take advantage of the specific characteristics of highly osteoporotic bones. Our aim is to simplify the osteotomy´s technique and make the surgery less invasive, decrease blood loss and the risk of neurological injuries to the spinal cord. Material and Methods: Between 2008 and 2018, surgery was performed in 14 patients (mean age of 71.4y.o) with unstable thoraco-lumbar fractures associated to kyphosis or sagittal malalignment. Presence of neurological deficits was identified in 5 patients. A posterior instrumentation with polimethylmethacrylate augmented screws and a modified PSO at the fracture level were performed to stabilize the spine and correct the kyphosis. The underlying principle behind our osteotomy´s technique is to exaggerate the defect caused by the fracture, complete the collapse of the fractured vertebra and shorten the spine. The procedure was divided in 4 steps.

- Step 1 completion of a wide laminoforaminotomy.

- Step 2: use of successive reamers inserted and rotated in the pedicle at a 25º angle in the axial plane to obtain a complete decancellation of the pedicle.

- Step 3: Insertion of the reamers in a more medial orientation (45º of angulation in the axial plane) to collapse the posterior wall. The dural sac was not manipulated at any time and the posterior longitudinal ligament was maintained.

- Step 4: Breakage of the lateral wall with an osteotome to complete the shortening of the spine

Radiographic and clinical outcomes were analyzed pre and post-operatively. Intraoperative blood loss and complications were cautiously reported. Results: Functional scores improved after surgery. Oswestry disability Index (ODI) and Visual analog scale (VAS) scores decreased significantly (33 and 4 points respectively). Both exceed the minimum clinically important difference of 20% for ODI and 2.2 points for VAS. All the patients with neurological deficits improved of at least one level of the ASIA scale. Patient satisfaction assessed at final follow-up shows a satisfaction rate of 93%. Average postoperative vertebral kyphosis was decreased to 0º and postoperative regional vertebral kyphosis to 3.79º. The mean correction angle for vertebral and regional kyphosis were 32º and 39º respectively. Mean hospital stay was of 9.7 days. 2 mechanical complications (Proximal Junctional kyphosis) were reported in a very short construct and in a patient with Parkinson disease. No dural tear or neurological injuries were observed. Compared to similar procedures, blood loss was low with a mean loss of hemoglobin of 3.1 g/dL. Conclusion: OVF are complex fractures that can lead to severe deformities and high morbidity. In osteoporotic bones, the use of sequential reamers can simplify the PSO technique allowing to shorten and stabilize the spine without manipulating the dural sac. The risk of neurological injuries and blood loss is then decreased.

715

P578: Management of AO Type C Thoracolumbar Fractures During Covid-19 Pandemic Using Distractor Device: A Novel Technique

Abhinandan Reddy Mallepally ¹ , Nandan Marathe ² , Bibhudendu Mohapatra ¹ , and Kalidutta Das ¹

¹ Indian Spinal Injuries Center, Spine Services, New Delhi, India

² Toronto Western Hospital, Neuroscience Center, Orthopaedics, Toronto, Canada

Introduction: Achieving good alignment even in patients who have sustained complete SCI, where neurological recovery may not be possible is crucial, as the reduced spine allows biomechanical stability and thereby facilitates rehabilitation. Management of these severe thoraco-lumbar (TL) spine fracture- dislocation injuries have been further complicated by the COVID-19 pandemic. COVID-19 has affected surgical practices severely and countries have run out of resources to treat patients The need to optimize resources and minimize the personnel in the operating room (OR) led us to develop a novel technique to reduce TL fracture dislocations (AO type-C) using an orthopedic distractor device (ODD). Materials and Methods: This prospective study was conducted at a tertiary care spine centre with a study duration from March 2020- May 2020 coinciding with the nationwide lockdown and travel restrictions imposed in view of pandemic. Only patients with AO type C fracture-dislocation managed using the ODD operated by a single surgeon were included in the study. Patients of pediatric age group, ankylosing spondylitis, those previously operated for spinal ailments were excluded. All patients were investigated in the form of X-ray, CT scan and MRI. Preoperative and post-operative neurology was noted as per ISNCSCI scale and VAS score for pain. Intra-operative data including the operative time and blood loss was noted. Variables assessed in radiological investigations were pre and post-surgery kyphosis and height loss. Our centre mandated that every patient should be tested for COVID-19 with nasal swab viral RT-PCR on admission. Hospital infection control committee convened through web based meeting developed redeployment strategy. Technique involved, gradual distraction and reduction under C-arm guidance until the facets were perched. A temporary contoured rod was placed on opposite side and fixed to lower spinal segment followed by gradual cantilevering onto the proximal segment aided by gradual distraction subsequently reducing the fracture by releasing the distraction under constant neuromonitoring guidance. This maneuver helps reduction of the dislocated spinal column in both planes (sagittal/ coronal). Results: Of 12 cases, most commonly affected level was D12-L1. 9 patients were AIS A at presentation, 2 patients were AIS B and one AIS C. The mean operative time was 125 minutes and mean blood loss was 454ml. 8 patients remained AIS-A, one patient improved from AIS-B to C. Two patients became independent walkers, one remained AIS-B. The post-operative VAS score improved to a mean value of 2.33. The improvement in kyphosis was 26.24⁰ immediate postoperatively and maintained at 25.9⁰, percentage height loss reduced to 2.75% immediate postoperatively and maintained at 3.16% at 3 months follow-up. None of the patients had CSF leak following the surgery from the wound. One patient developed gaping of the wound which required secondary suturing. Conclusion: The present study aims to provide some tips and pearls that we have learned in management of TL fracture dislocations in these trying COVID times of health care resource management. Reducing AO type C fractures can be challenging, especially in COVID times, for a single surgeon. The ODD is a useful technique for achieving the same.

790

P579: How Long It Takes to Operate Unstable Thoracolumbar Fractures in Latin America?

Alfredo Guiroy ¹ , Charles Carazzo ² , Juan Zamorano ³ , Juan Pablo Cabrera Cousiño ⁴ , Andrei Joaquim ⁵ , Joana Guasque ⁶ , Ericson Sfreddo ⁷ , Ratko Yurac ³ , and Asdrubal Falavigna ⁸

¹ Spanish Hospital, Orthopedics, Mendoza, Argentina

² Sao Vicente de Paulo Hospital, Passo Fundo, Brazil

³ Clínica Alemana, Santiago, Chile

⁴ Hospital Clínico Regional, Concepcion, Chile

⁵ University of Campinas, Sao Paulo, Brazil

⁶ Hospital Universitario Cajuru, Curitiba, Brazil

⁷ Hospital Cristo Redentor, Porto Alegre, Brazil

⁸ University of caxias do sul, Caxias do Sul, Brazil

Introduction: we aim to identify time to surgery for AO-Spine types B and C thoracolumbar fractures and the main reasons for delays across Latin America.Methods: We reviewed the charts of 547 patients with type B or C thoracolumbar fractures from 21 spine centers across nine Latin American countries. Data were collected on demographics, mechanism of trauma, time between hospital arrival and surgery, type of hospital (public vs private), fracture classification, spinal level of injury, neurological status (ASIA score), number of levels instrumented and reason for delay between hospital arrival and surgery. Results: The sample included 403 men (73.6%) and 144 women (26.3%), with a mean age of 40.6 years (range from 18 to 84 years-old). The main mechanism of trauma was falls (44.4%), followed by car accidents (24.5%). The most frequent pattern of injury was an AO Spine type B2 fracture (46.6%), and the largest proportion occurred at T12-L1 (42.2%). Admission neurological status was 60.5% neurologically intact and 22.9% ASIA A. The time from admission to surgery was over 72 hours in over half the patients and over a week in more than 25%. The most commonly reported reasons for surgical delay were clinical instability (22.9%), lack of operating room availability (22.7%) and lack of hardware for spinal instrumentation (e.g., screws/rods) (18.8%). Conclusions: Time to perform surgery in this sample of unstable fractures was over 72 hours in more than half the sample and longer than a week in about a quarter. The main reasons for this delay were economic. To increase funding for treatment of spinal trauma patients in Latin America is strongly necessary.

806

P580: Traumatic Conus Medullaris Syndrome (CMS): Results in Workers' Compensation Patients

Javier Lecaros ¹ , César Wilson ¹ , Ignacio Cirillo ¹ , Ignacio Farías ¹ , Alejandro Urzúa ¹ , and Vicente Ballesteros ¹

¹ Hospital del Trabajador, Santiago, Chile

Introduction: The CMS is a complete or incomplete spinal cord injury with multiple etiologies. The literature is limited and the current studies do not standardize the outcome for the management of traumatic injuries. Our purpose is to describe the pre and postoperative clinical presentation, and the long-term outcomes in patients with traumatic Conus Medullaris injury. Material and Methods: We evaluated the clinical records of patients with CMS secondary to fractures between T12 and L1, treated in the Hospital del Trabajador between 2009 and 2019. Demographic data, type of fracture, time of surgery, NASCIS II protocol, ASIA score, motor index score (MIS), bladder and/or intestinal dysfunction were described. Results: The average age was 40 (20-63) years old in 14 men and 4 women with spinal fracture between T12 and L1 (5 type A4, 4 type B2 and 9 type C). Ninety percent of the cases were operated before 24 hours after the injury occurred and in 31% of these the NASCIS II protocol was applied. Eighteen patients had intestinal and/or bladder disfunction at the hospital admission. Eleven patients presented with motor and/or sensitive deficit (91% bilateral). At the end of the follow-up (54 [2-148] months), 13 of the 18 patients (mostly ASIA D) improved 1 grade in the ASIA score, and 8 patients remained with bladder and intestinal dysfunction. Conclusion: Patients with traumatic CMS operated in the first 24 hours have a good neurologic prognosis, improving both in the ASIA score and in bladder/intestinal function.

861

P581: Clinical Relevance and Validity of TLICS System for Thoracolumbar Spine Injury

Sungkyu Kim ¹ and Sohyun Moon ²

¹ Chonnam National University Medical School and Hospital, Department of Orthopaedic Surgery, Gwangju, South Korea

² Chosun University, Department of Nursing, Gwangju, South Korea

Introduction: In order to enhance the reliability of the application to clinical practice of the TLICS classification, we retrospectively reviewed the patients with thoracolumbar spine injuries who underwent magnetic resonance imaging (MRI) and analyzed the validity of the TLICS classification and the necessity of MRI. Material and Methods: We enrolled 328 patients with thoracolumbar spine injury who underwent MRI. All patients were classified into conservative and operative treatment groups. The TLICS score of each group was analyzed and the degree of consistent with the recommended treatment through the TLICS classification was examined. Results: Of the total 328 patients,138 patients were treated conservatively and 190 patients were treated by surgery. Of the 138 patients who underwent conservative treatment, 131 patients (94.9%) had a TLICS score of 4 points or less, and matched with the recommendation score for conservative treatment according to the TLICS classification (match rate 94.9%, 131/138). Of the 190 patients who underwent operative treatment, 160 patients (84.2%) had a TLICS score of 4 points or more (match rate 84.2%, 160/190). All of 30 mismatched patients with a TLICS score of 3 points or less (15.8%) had stable burst fracture without neurological deficit. Conclusion: We retrospectively reviewed the validity of the TLICS classification for the injuries of the thoracolumbar spine, based on MRI in a large group of patients. Treatment with TLICS classification showed high validity, especially in conservative group, and MRI should be an essential diagnostic tool for accurate evaluation of posterior ligamentous complex injury.

866

P582: How Should Patients With a Thoracolumbar Injury Classification and Severity Score of 4 Be Treated?

Sungkyu Kim ¹ and Sohyun Moon ²

¹ Chonnam National University Medical School and Hospital, Department of Orthopaedic Surgery, Gwangju, South Korea

² Chosun University, Department of Nursing, Gwangju, South Korea

Introduction: Thoracolumbar fracture is one of the most common injuries that cause neurological damage, but its treatment remains controversial. The thoracolumbar injury classification and severity score (TLICS) system helps surgeons decide whether patients should undergo initial operative treatment or conservative treatment. However, the treatment of TLICS 4 fractures is based on the surgeon's discretion. The best treatment for patients with TLICS 4 fractures remains unknown. The aim of this study was to identify the risk factors for conservative treatment failure in patients with TLICS 4 fractures and establish a treatment standard for TLICS 4 fractures. Material and Methods: This study included 44 patients with TLICS 4 fractures who underwent early conservative treatment at our hospital from January 2010 to December 2016. Only patients with TLICS 4 fractures who initially received conservative treatment were included in this study. The risk factors of conservative treatment failure included patient sex, age, body mass index (BMI), initial visual analog scale (VAS) score, injury mechanism, spinal canal compromise, kyphotic angle, and loss of vertebral body height. We divided these patients into two groups: the successful conservative treatment group included 18 patients, and the operative treatment group after conservative treatment failure included 26 patients. The patients were followed up for at least 2 years after the initiation of treatment. The risk factors were compared between the successful conservative treatment and failed conservative treatment groups. Results: Spinal canal compromise (P = .03), loss of vertebral body height (P = .01), and kyphotic angle (P = .04) were associated with conservative treatment failure in patients with TLICS 4 fractures. Other factors, including age, sex, BMI, and initial VAS score were not significantly associated with conservative treatment failure in these patients. Conclusion: Spinal canal compromise, loss of vertebral body height, and kyphotic angle were associated with conservative treatment failure in patients with TLICS 4 (P < .05). Therefore, patients with TLICS 4 fractures and these associated factors may benefit from early operative treatment rather than conservative treatment.

876

P583: Effect of Pedicle Screw Placement Into the Fractured Vertebrae in Management of Unstable Thoracolumbar and Lumbar Fractures

Sasidharan M D S ^1,2 , Ishwara Keerthi ² , and Aditya Vardhan ²

¹ Apollo Hospitals, Spine Surgery, Chennai, India

² KMC Manipal Hospital, Spine Surgery, Mangaluru, India

Introduction: A prospective study was designed to determine whether Pedicle screw insertion at the level of fractured vertebra, known as intermediate screw has shown to improve clinical and radiological results in management of unstable thoracolumbar and lumbar vertebral body fractures. The aim of the study is to study the effect of placement of pedicle screw into the fractured vertebra in the management of unstable thoracolumbar and lumbar fractures. Materials and Methods: The study was conducted in Kasturba Medical College attached hospitals, Mangalore. 30 consecutive cases of unstable thoracolumbar and lumbar fracture were treated by short segment posterior instrumentation after approval from hospital ethical committee. Degree of initial spinal canal compromise, Pedicle diameter, indirect decompression, and remodelling were assessed from the computed tomography scans. The neurological status at the time of presentation and at final follow-up was assessed by the American Spinal Injury Association’s modified Frankel’s grading. Results: The median canal compromise in patients with and without neurological deficit was 31.59% (10.62) and 15.53 (7.70) respectively. The mean (SD) initial kyphotic angle was 15.54 (5.35) and the final kyphotic angle was 6.62 (2.57). The mean (SD) initial vertebral body height was 39.67% (8.04). The final vertebral body height at the end of 12 months follow-up is 70.38% (11.25). There is restoration of vertebral body height. A total of 180 pedicle screws were placed, 60 pedicle screws are placed at the level of fractured vertebra. Pedicle screw deviation was observed in total of 10 (13.33%) pedicle screws. There was no deterioration of neurology in patients with pedicle screw deviation, neurology remained the same. Conclusion: This study shows that Pedicle screw placement into the fractured vertebra in management of unstable thoracolumbar and lumbar fractures is safe and feasible, Short term benefits of placing pedicle screw into fractured vertebra are restoration of vertebral body height and kyphotic angle and indirect canal decompression.

1202

P584: Damage Control Surgery in Thoracolumbar Trauma: Our Experience

Álvaro Soteres ¹ , Ignacio ACuña ¹ , Jaime Cancino ¹ , Oscar Bravo ¹ , Guillermo Izquierdo ¹ , Felipe Novoa ¹ , and Manuel Valencia Carrasco ¹

¹ Hospital Clinico Mutual de Seguridad, Santiago, Chile

Introduction: Thoracolumbar junction fractures (T10 – L2) are the most common fractures of the spine. Between 40 and 80% of these fractures occur in the context of high energy trauma and lead to an eventual life-threatening condition. The concept "Damage Control Spine Surgery" consists of performing an early fixation from posterior approach, followed by the general stabilization of the patient and finally an eventual anterior approach as definitive treatment. The objective of this work is to present a series of cases of polytraumatized patients with spinal trauma, who were treated with damage control. Material and Methods: Retrospective study of polytraumatized patients with one or more thoracolumbar spine fractures, admitted to a Trauma Center in Chile during the years 2014 and 2019, for surgical resolution according to the Damage Control protocol. All patients were operated on by the same surgical team, with percutaneous schanz system. Patients with severe multiple trauma, ISS > 25, without neurological deficit and follow-up >1 year were included. The demographic characteristics of the patients, injury mechanisms, associated injuries, initial ISS, imaging measurements, length of hospitalization / ICU, complications and rehospitalizations were evaluated. Statistical analysis was performed with StataSE 12.0. Results: 14 patients were included in the study. 13 male patients and 1 female, with an age range between 33 and 65 years (median 49.5). The most frequent injury mechanism was a fall from height (7 patients, 50%). Upon admission, all patients had serious associated injuries. The average ISS upon admission was 40.5 (range 36-48). The thoracic and thoracolumbar segments were involved in a 1: 1 ratio, with a total of 15 vertebral fractures. Surgical resolution of these fractures from admission / was within 2.5 days. The average surgical time was 103 minutes with an average intraoperative bleeding of 82ml. There was no registry of bad positioning of the osteosynthesis, nor intraoperative complications. Conclusion: The MIS posterior fixation used in Damage Control for the treatment of thoracolumbar fractures is a very useful tool in multiple trauma patients. It allows us to reduce and stabilize these injuries early, facilitates nursing management, minimizes general and local complications, without delaying the stabilization and rehabilitation process of these patients.

1206

P585: Functional Outcome of Traumatic Spinopelvic Instabilities Treated With Lumbopelvic Fixation

Emre Yilmaz ¹ , Martin Hoffmann ¹ , Alexander von Glinski ¹ , Christiane Kruppa ¹ , Uwe Hamsen ¹ , Cameron Schmidt ² , Ahmet Oernek ³ , Matthias Königshausen ¹ , Marcel Dudda ⁴ , and Thomas Schildhauer ³

¹ BG University Hospital Bergmannsheil Bochum, Department of General and Trauma Surgery, Bochum, Germany

² Swedish Neuroscience Institute, Seattle, USA

³ BG University Hospital Bergmannsheil Bochum, Department of Radiology, Bochum, Germany

⁴ University Hospital Essen, Essen, Germany

Introduction: The aim of this study was to assess the functional outcome after lumbopelvic fixation (LPF) using the SMFA (short musculoskeletal functional assessment) score and discuss the results in the context of the existing literature. Methods: The last consecutive 50 patients who underwent a LPF from January 1^st 2011 to December 31^st 2014 were identified and administered the SMFA-questionnaire. Inclusion criteria were: (1) patient underwent LPF at our institution, (2) complete medical records, (3) minimum follow-up of 12 months. Results: Out of the 50 recipients, 22 questionnaires were returned. Five questionnaires were incomplete and therefore seventeen were included for analysis. The mean age was 60.3 years (32-86 years; 9m/8f) and the follow-up averaged 26.9 months (14-48 months). Six patients (35.3%) suffered from a low-energy trauma and 11 patients (64.7%) suffered a high-energy trauma. Patients in the low-energy group were significantly older compared to patients in the high-energy group (72.2 vs 53.8 years; P = .030). Five patients (29.4%) suffered from multiple injuries. Compared to patients with low-energy trauma, patients suffering from high-energy trauma showed significantly lower scores in “daily activities” (89.6 vs 57.1; P = .031), “mobility” (84.7 vs 45.5; P = .015) and “function” (74.9 vs 43.4; P = .020). Conclusion: Our results suggest that patients with older age and those with concomitant injuries show a greater impairment according to the SMFA score. Even though mostly favorable functional outcomes were reported throughout the literature, patients still show some level of impairment and do not reach normative data at final follow-up.

1226

P586: Predictors of Increased Length of Stay in Thoracolumbar Trauma Patients

Justin E. Kung ¹ , Jael Camacho ¹ , Jacob Bruckner ¹ , Daniel Cavanaugh ¹ , Eugene Koh ¹ , Daniel Gelb ¹ , and Steven Ludwig ¹

¹ University of Maryland School of Medicine, Department of Orthopaedics, Baltimore, USA

Introduction: Length of stay (LOS) has been suggested to be a meaningful outcome measure for more efficient and effective quality of care. Factors associated with increased LOS has yet to be investigated for patients who undergo surgical management for traumatic spinal fractures. The objectives of this study were to (1) identify preoperative, perioperative, and postoperative factors associated with increased LOS and (2) create predictive formulas to estimate LOS in thoracolumbar trauma patients who undergo surgical correction. Material and Methods: A billings database was queried for operative thoracolumbar (T1-L5) spine trauma cases from January 2012 to December 2017 at a Level 1 trauma and academic institution. Bivariate analysis between LOS and various preoperative, perioperative, and postoperative factors was conducted to identify significant associations. Multivariate analysis was conducted to create models capable of predicting LOS. Results: A total of 196 patients were included in this study with a median LOS of 6.7 days. LOS was significantly associated with various preoperative (e.g. Charlson Comorbidity Index, Glasgow Coma Scale (GCS), Injury Severity Score), perioperative (e.g. length of surgery, number of instrumented segments, surgical technique), and postoperative variables (e.g. complications, discharge location). Multivariate analysis of preoperative variables identified five significant independent predictors that could predict LOS with strong correlation with observed LOS (P =.63). With all variables considered, multivariate analysis identified eight variables (GCS, American Society of Anesthesiologists score, neurological status, polytrauma, packed red blood cell transfusion, number of unique postoperative complications, skin complications, and discharge facility) that could predict LOS with strong correlation (P = .80). Conclusion: Various preoperative, perioperative, and postoperative factors are significantly associated with LOS in traumatic thoracolumbar spine patients. We developed models with good predictive capacity to predict LOS. If validated, these models should help in risk stratifying patients for increased length of stay and consequently improve preoperative patient counseling.

1517

P587: Improvement of the Anterior Vertebral Body Fracture Reconstruction Using a Dorsal Reduction Tool

Kristina Kaufmann ¹ , Thomas Schildhauer ¹ , and Martin Hoffmann ¹

¹ Berufsgenossenschaftliches Universitätsklinikum Bergmannsheil, Bochum, Germany

Introduction: Vertebral body fractures in the thoracolumbar region often lead to kyphotic malalignment. Therefore, surgical treatment aims for reduction of sagittal alignment and reconstruction of the anterior column. Sufficient elevation of the anterior edge of the vertebra might possibly prevent the necessity of additional anterior stabilization or vertebral body replacement. The purpose of this study was to examine whether greater anterior reduction can be achieved by utilizing a reduction tool and whether postoperative loss of vertebral height can be reduced. Material and Methods: Between 2015-2020, 90 patients with A3/A4 fractures of the thoracolumbar region underwent posterior bisegmental stabilization in one level I trauma center. A reduction tool (Nforce, Medtronic) (IG) was utilized in 37 cases. 53 patients were only reduced through intraoperative positioning and served as control group (CG). To assess the bony reduction result, the vertebral kyphosis angle was measured pre-/postoperatively and after osseous consolidation. Additionally, the percentage of height reduction was determined by measuring the anterior and posterior edge of the fractured vertebral body on X-Ray and CT images. Clinical outcome was assessed by Ostwestry Disability Index (ODI). Results: No differences in terms of gender and comorbidities were found between the two groups. Mean age was 42 years in the IG and 48 years in the CG (P = .02). At the time of fracture, the anterior vertebral height was reduced by 31% in the IG and 26% in the CG (P = .04), resulting in a kyphosis angle of 15° vs 12°, respectively (P = .01). Intraoperatively, the anterior column was reduced by 20% (CG 12%, P < .001) with the reduction tool and the kyphosis angle corrected by 9° (CG 5°, P < .001), so that initially greater kyphosis could be compensated. Postoperatively, there were no significant differences in height reduction (P = .09) and angle (P = .2). Despite greater postoperative loss of reduction for patients in the IG with 13% vs 8% in the CG and a loss of correction of the vertebral angle in the IG with 5° vs 3° (P < .05), the overall reduction from time of fracture to osseous consolidation resulted in better reconstruction of the anterior column with 8% and correction of the angle by 4° in the IG compared to the CG with 3% and 2°, respectively (P < .05). There was no difference in the clinical outcome determined by the ODI (IG = 17% vs CG = 25%; P = .2). Conclusion: Utilizing a reduction tool during posterior stabilization of vertebral body fractures in a suitable collective of young patients with good bone quality and severe fractures may lead to a significantly better reconstruction of the ventral column of the fractured vertebral body and angle correction. Therefore, additional surgery or vertebral body replacement may be possibly prevented.

1562

P588: Sternal and Thoracic Spine Fractures: Further Analysis of the 4-Column Theory

Patrick Curtin ¹ , Jay Patel ¹ , Jenna Lansbury ¹ , Taylor Dickinson ¹ , and Michael Stauff ¹

¹ University of Massachusetts, Orthopedic Surgery, Worcester, USA

Introduction: The sternal-rib complex has been recognized as a key stabilizer of the thoracic spine. Thoracic spine fractures (TSFs) with associated sternal fracture has been described as a “4 column injury”. Previous studies however, have had limited patient numbers and include any TSF type making conclusions about this injury pattern difficult. The purpose of this study is to better characterize TSFs with sternal fractures, their associated injuries, and their treatment. Material and Methods: We retrospectively reviewed the trauma database records of 3646 patients presenting with a TSFs at a single institution from 2015 to 2019. Forty patients were identified as having a TSF and a sternal fracture. For these forty patients we recorded patient demographics, comorbidities, and associated injuries by body region. We characterized the TSFs using the AO classification system, as well as the presenting physical exam and treatment. Results: Of the 40 patients with TSFs and a sternal fracture, 15 were found to have a true ‘3 column injury’. The average age was 64.9 years. Seven patients had injuries due to motor vehicle crashes (MVC), 6 from fall from height, 1 from mechanical fall, and 1 pedestrian struck by motor vehicle. Twelve (80%) patients TSF was at the level of T6 or above, with 3 (20%) at T7 or below. 33.3% of patients had significant hyperostosis of thoracic spine. 86.7% had multiple rib fractures, 26.7% had significant head injuries with associated intracranial hemorrhage, 46.7% had an abdominal injury, 40% had an upper extremity injury, 20% had a lower extremity injury, and 20% had an ASA A spinal cord injury. All patients had additional injuries to their TSF and sternal fracture. Of the 15 patients, 6 were treated with surgery for their TSF, 7 were treated definitively with bracing, and 2 died during initial hospitalization due to associated injuries. Of the remaining 25 patients with TSFs with sternal fracture, all TSFs were compression fractures. The average age was 64.4. Fourteen patients had injuries due to MVC, 6 from mechanical fall, 2 from sports, 2 from motor cycle crashes, and 1 from fall from height. 16% of patients had significant hyperostosis of the thoracic spine. Associated injuries occurred less frequently, with 52% having multiple rib fractures, 4% having significant head injuries with associated intracranial hemorrhage, 12% with an abdominal injury, 16% with an upper extremity injury, 32% with a lower extremity injury, and 0% having a spinal cord injury. Of the 25 patients, 6 were treated definitively with bracing for their TSF, and the remaining 19 patients did not require further intervention. Conclusion: Patients with a true 3 column fracture of the thoracic spine and a sternal fracture had a high percentage of associated injury, need for treatment for their TSFs, and mortality. Future research is needed in order to determine the overall importance of surgical stabilization of the thoracic spine fracture and the timing of the stabilization for ultimate patient outcome in these complex injuries.

1564

P589: Hyperostosis in Patients With Thoracic Spine Fractures

Patrick Curtin ¹ , Jay Patel ¹ , Jenna Lansbury ¹ , Taylor Dickinson ¹ , and Michael Stauff ¹

¹ University of Massachusetts, Orthopedic Surgery, Worcester, USA

Introduction: Hyperostosis of the spine (ankylosing spondylitis or diffuse idiopathic skeletal hyperostosis) is a known risk factor for increased severity of spinal injury with trauma due to the increased rigidity. Due to the impact of hyperostotic disorders on the severity of spinal fractures, treatment for these injuries is more complex. Despite this observation, there have been few studies that quantify patient outcomes. The purpose of this study is to better quantify severity of injury based on mechanism in patients with thoracic spine fractures (TSFs) and hyperostosis. Material and Methods: We retrospectively reviewed the trauma database records of 557 patients presenting with a TSFs at a single institution from 2015 to 2019. Of these patients, 154 were identified as having significant, multi-level hyperostosis. For all patients, we recorded patient demographics, comorbidities, and associated injuries by body region. We characterized the TSFs using the AO classification system, the presenting physical exam/treatment, and follow-up visits. Results: The average age for patients with TSFs and hyperostosis was 75.3 years, and 53.9 years for patients without hyperostosis. TSFs both with hyperostosis and without had high rates of additional injury from all mechanisms, with thoracic injury (TI) (42.9% vs 41.4%, P = .76), non-thoracic vertebral injury (NTVI) (36.4% vs 38.7%, P = .51), abdominal injury (AI) (15.0% vs 11.4%, P = .26), head injury (HI) (42.9% vs 41.4%, P = .64), upper extremity injury (UEI) (15.0% vs 17.0%, P = .53), and spinal cord injury (SCI) (1.2% vs 2.0%, P = .59), however none were statistically different. Lower extremity injury (LEI) was statistically lower in patients with hyperostosis (9.7% vs 17.4%, P = .025). Patients with hyperostosis and TSFs from all mechanisms had a significantly higher need for bracing (65.0% vs 52.6%, P = .0087) and similar rates for surgery (7.8% vs 8.9%, P = .67) for treatment of their TSFs compared to patients without hyperostosis. Mechanical falls was the most common mechanism causing TSF in both patients with hyperostosis (73) and without hyperostosis (136). Patients with hyperostosis had higher rate of NTVI (31.5% vs 27.9%, P = .60) and a lower rate of TI (19.2% vs 27.9%, P = .1624), however neither were statistically different. One patient with hyperostosis presented with an Asia A SCI. Patients with hyperostosis and TSFs from a mechanical fall had a significantly higher need for bracing (63.0% vs 44.9%, P = .012) and similar rates for surgery (5.5% vs 1.5%, P = .10) for treatment of their TSFs compared to patients without hyperostosis. Classification of TSF was more severe in patients with hyperostosis, with a higher percentage being an AO classification B or above compared to patients without hyperostosis (35.6% vs 16.2%, P = .0015). Conclusion: TSFs have a high rate of associated injury, regardless of hyperostosis status. Despite similar rates of surgery, patients with hyperostosis were much more likely to require bracing for treatment of their TSF. This further reinforces that TSFs in patients with hyperostosis do not necessarily require surgery, and can be treated definitively with bracing.

1640

P590: Kyphoplasty Versus Vertebroplasty in the Treatment of Vertebral Compression Fractures in Patients With Osteoporosis: A Meta-Analysis

William Zarza Santos ¹ , Nelson Astur ¹ , Leandro Kim ¹ , Lucas Miotto ¹ , Rodrigo Goes ¹ , Alberto Gotfryd ¹ , Maria Fernanda Caffaro ¹ , and Robert Meves ¹

¹ Hospital Santa Casa de São Paulo, Ortopedia e Traumatologia - Coluna, São Paulo, Brazil

Introduction: Vertebral fracture is the main complication of osteoporosis and occurs frequently in the elderly. Conservative treatment is the first choice for osteoporosis vertebral compression fractures (OVCF), being very efficient in most cases. However, for persisting painful cases, vertebral cemented percutaneous augmentation techniques such as vertebroplasty and kyphoplasty are indicated, aiming to reduce pain and improve patient's functional status. We performed a systematic review of the literature and meta-analysis to compare clinical and radiological outcomes of both methods. Material and Methods: A systematic literature review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) and Cochrane Handbook of Systematic Reviews. The PICO search strategy was: Population- Patients with OVCFs; Intervention- Kyphoplasty; Control- Vertebroplasty; Outcomes- Pain, Cement Leakage, Vertebral Body Height, Adjacent level fractures, Oswestry (ODI) and SF36. Only randomized controlled trials comparing both interventions were considered for analysis. Results: After full literature search, seven articles were included in qualitative analysis. We identified a total number of 919 patients. Among these 450 patients were treated with vertebroplasty (VP) and 469 with kyphoplasty (KP). The leakage rate of the VP group was 63% versus 14% of the KP group. However, it did not reach 5% level of statistical significance to differ Cement Leakage rate between KP and VP. The Visual Analogue Scale (VAS), ODI and SF-36 outcomes were evaluated considering 6-months and 1-year follow-up results and we could not point out differences between treatments at a significance level of 5%. Finally, KP presents average .71 cm higher values than VP for vertebral body height restoration, with 95% CI. Conclusion: In this systematic review and meta-analysis, the use of kyphoplasty was superior to vertebroplasty for vertebral body height gain. There was no statistically significant superiority between the two methods for cement leakage and other clinical outcomes.

1641

P591: Upper Thoracic Spine Fractures Healing Rates and Complications in King Abdulaziz Medical City, Riyadh, Saudi Arabia

Fai Alhoshan ¹ , Faisal Konbaz ² , Sumaia Alqaseer ¹ , Fahad Alhelal ² , Ali Alhandi ² , and Abdullah Alsaeed ³

¹ King Saud bin Abdulaziz University for Health Sciences, College of Medicine, Riyadh, Saudi Arabia

² King Abdulaziz Medical City, Department of Orthopedic Surgery, Riyadh, Saudi Arabia

³ Unaizah College of Medicine and Medical Sciences, Qassim University, Kingdom of Saudi Arabia, Department of Surgery, Unaizah, Saudi Arabia

Introduction: Upper thoracic spine fractures (T1-T6) are not uncommon. There is a controversial discussion in the literature regarding the treatment choices for unstable upper thoracic fractures. Thoracic pedicle screw (PS) fixation has replaced all other fixation techniques for its success rate and safety. Complications postoperatively included hardware failure, progressive kyphosis, redislocation, lordotic changes, and back pain. In this study, our aim is to assess the healing rate in traumatic upper thoracic fractures and its association with other orthopedic injuries, and to Measure the magnitude of kyphotic and lordotic deformities and changes in cervical spine post-op in King Abdulaziz Medical City, Riyadh. Methodology: This is a retrospective chart review study including all adult cases diagnosed as traumatic upper thoracic spine fractures in KAMC in Riyadh. The data was abstained from the computerized database. Information about the timing and type of fracture, pre and post-operative assessment, follow up duration, and the presence of complications. Data was analyzed by using SPSS v21. Result: The total number of cases included in this study was 16 cases. Of which 12 (75%) were male. The average age of cases was 29.9 years. Other spine fractures were found in 10 cases (62.5%), associated thoracic cage fractures 11 cases (68.75%), and 13 cases (81.25%) had other associated injuries distributed all over their bodies. All cases underwent posterior decompression and instrumentation and fusion fixation. Three cases (18.75%) had a fixation crossing the cervicothoracic junction. Ten patients (62.5%) needed an ICU admission post-operatively. Two patients developed chest infections and one had septic shock as post-op complication and died. No significant differences were noticed between the pre and post-operative ASIA score, except for one patient who improved post correction from ASIA A to ASIA C. The average pre-op fracture COBB’s angle was 29.9, while the post-op fracture COBB’s angle was measured as 22.22. The result showed an improvement in the post-op fracture COBB’s angle indicating good fixation technique. No significant increase in postoperative upper thoracic kyphosis postoperatively. Only 3 Patients (18.75%) had increased Postoperative lordosis with acceptable lordosis preoperatively. Conclusion: Our findings correspond to the literature discussion that the current practice in managing traumatic upper thoracic spine fracture in KAMC in Riyadh is relatively safe and effective. Yet, further studies are needed to elaborate more in the relationship between presence of other injuries, level of injury, and patient’s factors and post-operative outcomes.

1767

P592: Is Fusion Necessary in AO Type C Injuries of Thoracolumbar Spine

Ajoy P Shetty ¹ , Chandhan Murugan ¹ , Vibhu Krishnan Viswanathan ¹ , and Shanmuganathan Rajasekaran ¹

¹ Ganga Medical Center and Hospitals, Coimbatore, India

Introduction: Non- fusion surgeries are the currently the “gold standard” in the management of a majority of unstable AO types A and B fractures. The purported advantages of this approach include shorter duration of surgery, lesser blood loss and reduced surgery-related morbidities. There is paucity of studies on surgical management of type C injuries; and current literature still recommends fusion surgery as the most acceptable approach. The current study was thus planned to determine the safety of non-fusion surgery in patients with type C TL injuries and to evaluate long-term clinical and radiological outcome in these patients. Methods: This retrospective study included 35 patients, aged between 18 and 65 years, who presented to our Emergency Department with AO type C TL injury between August 2015 and July 2018. Only patients with normal, pre-operative neurological status and those who underwent long-segment, posterior (extending two levels proximally, one/ two levels distally and atleast one screw at fracture level) without fusion were included. All patients with follow-up <2 years and inadequate clinico-radiological details were excluded. Plain radiographs were assessed for wedge angle, regional angle and sagittal index at pre-operative period and each follow-up visit. The functional outcome was assessed using Oswestry Disability Index score at the end of 2 years. The statistical methodology followed was Wilcoxon test for paired samples and Pearson correlation for unpaired samples. Results: The study included 35 patients [25 males (71.4%)] with AO type C injury of the thoracolumbar spine with normal neurology. The age group ranged from 18 to 65 years with a mean age of 30.7 ± 12.8 years. The mean pre-operative regional kyphotic angle decreased from 19.8 ± 13.7 degrees to 6.6 ± 11.3 degrees immediately following surgery. There was a statistically significant loss of correction to 8.7 ± 10.4 degrees at 6 months (P = .005) and 9.21 ± 10.5 degrees at the end of 2 years (P = .003). The mean sagittal index increased from .58 ± .2 pre-operatively to .77 ± .17 following surgery without a significant change to .75 ± .2 at the end of 2 years (P = .443). The wedge angle preoperatively was corrected from a mean value of 21.21 ± 10.5 to 12.25 ± 7.8 following surgery without a significant change to 12.41 ± 8.1 at the end of 2 years (P = .690). The functional outcome was measured using the Oswestry Disability Index, 80 % of the patients reported a score <20% (minimal disability) while 20% had a score between 20a and 40% (moderate disability). The Pearson correlation (-.023) ruled out a significant relationship between functional outcome and loss of correction (P = .898). Conclusion: “Posterior instrumented stabilization without fusion” is a safe procedure in patients sustaining AO type C injuries of TLS with normal neurological status. Although there is some statistically significant loss of kyphosis correction over the initial two years post-operatively, the overall functional outcome remains satisfactory in these patients following this procedure.

1794

P593: Management of Cement Leakage After Pedicel Screw Augmentation

Renate Krassnig ¹ , Ortner Thomas ² , Schwarz Angelika ² , Wildburger Renate ¹ , and Hohenberger Gloria ³

¹ AUVA Rehabilitation Clinik Tobelbad, Tobelbad, Austria, ² AUVA Traumahospital Graz, Graz, Austria, ³ University Hospital of Orthopaedics and Trauma, Graz, Austria

Introduction: Loosening and pull out of pedicle screws are common problems in spine surgery. Therefore more and more pedicle screws are used with cement augmentation, especially in osteoporotic bone. A feared complication is cement leakage into the venous system with consecutive pulmonary cement embolism. Evidence based recommendations to handle these complications are rare. Material and Methods: Case report: In a 59-year-old female patient with a burst fracture of the first lumbar vertebrae, cement leakage into the inferior vena cava over a distance of 4 cm occurred during a spondylodesis with cement augmented pedicle screws. A review of the literature followed by an interdisciplinary discussion panel including a trauma surgeon, a vascular surgeon, an angiologist and an interventional radiologist was performed to determine the most appropriate intervention with the lowest possible patient risk. Results: Incidences of cement leakage are described very vague in the literature. Most cases occur asymptomatic and the most abundant complication is a pulmonary cement embolism. Treatment recommendations include observation, temporary oral anticoagulation, percutaneous interventional removal, and open procedures. In our case, we decided – due to the thromboembolic risk and the relatively young patient – to attempt percutaneous interventional cement removal by an interventional radiologist with a vascular surgeon and cardiac surgeon on standby. After catching the cement line with a snare, the cement became aberrant and moved into the right atrium. From the right atrium the major part could be secured piecewise with the snare. A small part however caused a peripheral pulmonary cement embolism. Within the first three months postoperatively the patient remained asymptomatic under oral anticoagulation with Phenprocoumon. Conclusion: Recommendations for the management of cement leakage of augmented pedicle screws do only exist on observations in small series and case reports. Prospective clinical trials are not expected to be available in the near future. An interdisciplinary approached is obligatory for a good treatment outcome.

1883

P594: Comparison of Titanium and PEEK Expansible Cages for Anterior Column Reconstruction in Trauma Patients. Complete Follow Up of 89 Patients

Cristhopher Mazuret^1,2, Christoph Albers², Lorin Michael Benneker², Sebastian Bigdon², and Moritz Deml²

¹ Complejo Asistencial Dr Sotero del Rio, Orthopaedics and Trauma Surgery, Santiago, Chile

² Inselspital, University Hospital of Bern, University of Bern, Department for Orthopaedics and Trauma Surgery, Bern, Switzerland

Introduction: Recent studies demonstrated the safety and clinical effectiveness of modular, expandable PEEK-cages for anterior column reconstruction in thoracolumbar trauma and tumor diseases. Expandable or mono-bloc titanium cages are the gold standard in anterior spinal column reconstruction. PEEK-cages have shown exceedingly low loss of correction through the entire follow up, but there is no study comparing the sagittal profile reconstruction in mid- to long-term follow-up comparing titanium cages with those made from PEEK in thoracolumbar corpectomy due to trauma. Purpose: We aim to compare the loss of correction of a cohort of trauma patients treated with a modular, expandable cage made from PEEK cage vs a titanium cage. Material and Methods: We included 43 patients from 2013 to 2017 with a traumatic thoracolumbar fracture treated with a PEEK modular expandable implant (PG) and compared them to a cohort of 46 patients treated with a titanium modular expandable cage (TG). We excluded any other diagnosis (tumor, infection, and degenerative disease), other spinal regions (cervical and thoracic). The overall follow-up was 17, 9 months in the PG and 20,5 months in the TG. We assessed the bi-segmental kyphotic angle (BKA) before and after the surgery and at the last follow up point. We also assessed screw loosening, subsidence and tilting of the cage at the same time points. Results: Preoperative data showed a significant difference for age (39.2 ±14.8 vs 45.7 ±14.6, P = .02, PG vs TG) and neurologic impairment (P = .03) but no for gender (P = .47) and polytrauma (P = .4). Before and after the surgery, there were no differences between the PG and TG (P = .47 and P = .18), both showing a correction of 12.0 and 11.3 degrees (P < .001; P < .001) respectively. At the last follow-up the PG showed 2.5 degrees (P = .36) against a 4.3 degrees (P = .04) loss of correction for the TG. We also found a subsidence of 3.2 mm and 2.1 mm and a tilting of 1.7 and 2.6 degrees for the PG and TG, respectively. There was no significant difference in screw loosening (xx/43 vs xx/46). Conclusion: Titanium and PEEK cages are reliable and show a small loss of correction for the entire follow in thoracolumbar trauma. The PG showed a statistically smaller loss of correction (2.5 vs 4.3 degrees; P = .04). The long-term clinical meaning of this difference is yet to be known.

1885

P595: Decision Making in Thoraco-Lumbar Burst Fracture: Contribution of Interpedicular Distance

Mouadh Nefiss ¹ , Ayari Sakr ¹ , Nouira Amine ¹ , Saied Abdellali ¹ , Ezzaouia Khelil ¹ , Bouzidi Ramzi ¹ , and Tborbi Anis ¹

¹ Mongi Slim Hospital, Orthopedic Surgery Department, La Marsa, Tunisia

Introduction: Decision making in thoracolumbar burst fractures is based on clinical and standard radiological criteria especially when access to CT-scan is not that easy. Various radiographic parameters have been used to predict severity and treatment outcome such as regional kyphosis (RK) and loss of vertebral height (VH).The inter-pedicular distance (IPD) is a parameter that can be easily measured on plain radiographs, and previous studies have attempted to identify the role of IPD in evaluating the severity of burst fractures. The objective of our study was to evaluate the relationship between (IPD) and the assessment of the severity of burst thoracolumbar fractures. It also aimed to provide an overview of the diagnostic and prognostic value of the IDP. Material and Methods: We conducted a retrospective study of prospectively collected data of 26 patients who had a thoraco-lumbar burst fracture (type A3 and A4 according to the AO classification) between January 2015 and December 2017. Standard X-rays and CT images were taken pre-operatively. The IPD was calculated on the basis of measurements made on standard radiographs, using the Caffaro and Avanzi formula. Spinal kyphosis (SK) was defined as the angle between the upper and lower plateaus of the fractured level. Vertebral body height loss (VH) was calculated as the percentage of anterior vertebral body height (AVH) relative to the average AVH of the adjacent upper and lower levels. Results: A total of 26 patients (21 men and 5 women) with an average age of 43.7 years were included. Mechanisms include falls from height and road accidents. 95.15% showed an increase in IPD from 1.41% to 41.53%. There was a difference between the variation in IPD values observed with a fractured lamina (mean = 14.1) and an intact lamina (mean = 7.1) but without statistical significance. Regarding the relationship between IPD and radiographic parameters, statistical analysis showed a positive correlation between IPD and SK. However, no statistically significant relationship was observed between IPD and loss of VH. Conclusion: Our results indicate that IPD can have q diagnostic value in the evaluation of thoracolumbar burst fractures and in decision making in case of difficulties to obtain a better evaluation with CT-scan.

1937

P596: Post-Traumatic Vertebral Fractures in Ankylosing Spondylitis

Khalil Habboubi ¹ , Hassen Makhlouf ¹ , Jribi Haythem ¹ , Ayachi Montassar ¹ , Lanouar Bouzid ¹ , and Mondher Mestiri ¹

¹ Kassab Institute, Tunis, Tunisia

Introduction: Spinal fractures in patients with ankylosing spondylitis (AS), occur mainly in the cervical and thoracic levels and may be responsible for neurological and vascular complications. We reported the case of a fracture dislocation of the lumbar spine in a patient with AS and we studied the characteristics of these lesions. Methods: We reported the case of a 46 year old man, with 16 years history of AS, suffered a low energy road traffic accident causing an isolated trauma of the thoracolumbar spine in hyperextension. Clinical examination found a stiff thoraco-lumbar spine with exquisite pain on the palpation of the spinous process of L2. Peripheral pulses were present and symmetrical. Neurological examination found a complete paraplegia with priapism. Plain radiographs showed a stiff spine, completely fused with a double rail aspect and an L2-L3 dislocation. The patient underwent surgery. Fracture was reduced by external maneuvers. After a short laminectomy, a postero-lateral bone grafting with L1-L4 fixation was done through a posterior approach. Results: At a one year follow-up, patient was still in rehabilitation with no signs of neurological recovery. On last CT scan, vertebral body isn’t consolidated yet, but we obtained a good postero-lateral fusion. Conclusions: The AS affects approximately 1.6% of the population. The incidence of fractures of the spine during the AS is difficult to measure: it is variable according to authors, 8 cases in 5 years for Murray, 1 in 300 spinal fractures for Hannequin. The majority of fractures occurs AS patients with severe spinal ankylosis extent. The average age is varying from 19 to 25 according to authors. Trauma is usually minimal, and would have remained without consequences for a healthy spine. Forty-six percent of fractures occur after minor trauma, and 7% in the absence of trauma. The lumbar spine is affected in 10% of cases while the cervical spine is most commonly affected with 75% of cases followed by the thoracic spine with 15% of cases. Spinal fractures during an AS has its own characteristics. The possibility of severe neurological complications justifies the use of CT scan or MRI to address the shortcomings of conventional radiology.

1939

P597: Spontaneous Nonunion in Spinal Fractures in Patient With Ankylosing Spondylitis

Khalil Habboubi ¹ , Hassen Makhlouf ¹ , Meddeb Mehdi ¹ , Chaker Mohamed ¹ , Lanouar Bouzid ¹ , and Mondher Mestiri ¹

¹ Kassab Institute, Tunis, Tunisia

Introduction: Several spinal complications can occur in a patient with ankylosing spondylitis. Extensive disco-vertebral destructive lesions are known but rare and may be associated with sagittal imbalance and pain symptoms resistant to medical treatment. We reported through this work a new case of spontaneous spinal nonunion in a patient with ankylosing spondylitis. Observation: This was a 38 year-old patient followed for ankylosing spondylitis for 20 years who consulted for pain in the thoracolumbar junction lasting for 2 years and resistant to medical treatment. A dynamic CT scan showed a totally fused thoracolumbar spine except for the D11-D12 level where there was a posterior vertebral arch and superior endplate disruptions with sings of instability on CT cuts in kyphosis. An additional MRI showed inflammatory spondylitis and an angioma of D11. The patient initially was treated with a thoracolumbar corset without sensible improvement. Surgical treatment was indicated given the persistence of pain. He had a posterior approach with D10-L2 fixation and posterolateral graft followed by a second procedure through a retro-peritoneal extrapleural anterior approach, given access to the endplate nonunion and the interposition of an autologous tri-cortical bony graft. Discussion: These lesions have been described for the first time in 1937 by Anderson, since then, several theories have been advanced to explain these disco-vertebral damages. It was Wu PC, Ho E et al. who studied first the pathophysiology of this complication and demonstrate the role of articular processes fractures in the genesis of these lesions. Several mechanisms may explain the occurrence of this nonunion:

- The persistence of a certain disc mobility leads to an escaping phenomenon to the global spinal fusion.

- A secondary fracture of the articular processes, following a benign spinal trauma.

- A stress fracture of the posterior articular processes, on an ankylosed and kyphotic spine.

Several cases were reported in the literature, the orthopedic treatment hasn’t given good results and authors agree on the need for a circumferential vertebral fusion of the articular processes fractures posteriorly and vertebral endplates, anteriorly. Conclusion: Spinal nonunions in patients with ankylosing spondylitis are rare but their ignorance can lead to serious functional complications. Conservative treatment isn’t sufficient in the treatment of the spinal nonunions. Only a circumferential graft through a double surgical approach is recommended for this type of injury, for better chances of consolidation.

1965

P598: Clinical results in Anterior Monosegmental Fusion With the Trabecular-Metal-Cage in 95 Trauma Cases of Unstable Fractures of the Thoracolumbar Junction

Stefan Hauck ¹

¹ Trauma Center Murnau, Spine surgery, Murnau, Germany

Introduction: Unstable vertebral body fractures of the thoracolumbar junction of the type AO A3.1 are generally treated by ventral monosegmental spinal fusion. The support is provided by iliac crest bone graft. This results in part of the cases in cracks or necrosis of the graft or in lack of connection to the end plate. The contact area and chip cross-sections are very different, associated with the donor site morbidity. Cages, as the trabecular metal cage, with large contact surface (2 * 3 cm) and cancellous structure can replace the iliac crest grafts. Materials and Methods: In a prospective study 95 patients with unstable vertebral body fractures and ventral defect situtation, most of them were initially instrumented posterior bisegmental, were treated by thoracoscopic anterior implantation of a trabecular metal cage for monosegmental fusion with plate fixation. The patients underwent radiological examinations during the course (gain of correction, loss of correction), as well as evaluation of satisfaction by Odom score. Results: In the period from Januar 2010 to Dezember 2013 95 patients with fresh unstable vertebral fractures were treated by ventral monosegmental spondylodesis with a trabecular metal cage instead of iliac bone crest. 37 women and 58 men showed fractures type A1.2, but most type A3.1 of the thoracolumbar junction. The mean age was 47.1 years / - 11.5 (min 24, max 74). The average operational time was 105 min / - 27 (Min 56, Max 177). The follow-ups after 3,6 months and most 1 year demonstrated good results. The loss of correction was small. All cages integrated firmly, the patients were largely asymptomatic. The removal of the internal fixator was between 4 - 8 months. Conclusion: The implantation of a trabecular metal cage with cancellous bone structure can replace the iliac crest bone graft in the monosegmental ventral management of unstable spinal fractures. In contrast to ventral spondylodesis by iliac crest bone grafts fusion and consolidation results after 3 months, a loss of correction hardly occurs. In addition there is no donor site morbidity and operational time is reduced.

Trauma—Other

11

P599: Clinico-Radiological Outcomes of the Surgically Managed Osteoporotic Thoracolumbar Burst Fracture - All Posterior Approach

Ghanshyam Kakadiya ¹ , Viraj Gandbhir ¹ , and Prashant Gedam ¹

¹ Topiwala National Medical College & Nair Hospital, Orthopaedics, Mumbai, India

Introduction: The incidence of wedge fractures in the osteoporotic spine is gradually increasing with increasing life expectancy. Most osteoporotic fractures are well managed conservatively. Osteonecrosis of fractured vertebrae can lead to non-union and delayed collapse, that can result in progressive kyphosis with the possibility of delayed neurological deficit. The purpose of this study was to evaluate a novel effective procedure utilizing three-column reconstruction via a posterior approach with a technique that utilizes an arthroscope to visualize the anterior surface of the dura during decompression. Material and Methods: A Prospective Study. 80 Osteoporotic vertebral burst fracture patients with similar demographic data, clinical parameters (Visual Analog Scale VAS, Oswestry Disability Index ODI, Frankel grade) and radiological parameters (BMD, kyphosis) managed by three-column reconstruction through single posterior approach surgery: Pedicle screw fixation, Corpectomy, Arthroscope Assisted Transpedicular Decompression (AATD) and Fusion (Mesh Cage + Bone grafting). Preoperative data, postoperative data, surgical variables and complications were recorded and analysed. Results: No significant differences in demographic data. Significant improvement was noted in VAS (pre-operative, 7.90 ± .60; final follow-up 2.90 ± .54) and ODI (preoperative, 77.10 ± 6.96; final follow-up 21.30 ± 6.70). Neurological improvement was noted in 74 patients (Frankel grade E) while six patients remained non-ambulatory (Frankel grade C). Significant improvement was noted in local kyphosis angle (preoperative, 22.14 ± 2.60; postoperative, 10.40 ± 1.40) with a 10% loss of correction (2.5 ± .90) at final follow-up. Implant failure in two patients and proximal junctional failure in two patients managed with revision surgery. No iatrogenic dural or nerve injury. Conclusion: Osteoporotic Burst fracture can be managed with single posterior surgery, three-column reconstruction with mesh cage. It provides a significant improvement in clinical, radiological and functional outcomes. The arthroscope can improve a surgeon's operative field and magnification thereby ensuring complete decompression without injuring the dura or spinal cord.

17

P600: Iatrogenic Spinal Cord Injury - Neurological and Functional Outcome at a Dedicated Spinal Cord Injury Rehabilitation Centre

Aashish Ghodke ¹ and Navin Kumar ¹

¹ Robert Jones & Agnes Hunt Orthopaedic Hospital, Oswestry, United Kingdom

Introduction: The incidence of iatrogenic injury is more than what is quoted in the literature. There are very few cases reported in literature due to the fact that sometimes iatrogenia is linked with malpractice and has many legal, ethical and financial implications. Aim of our study was to determine the incidence and common etiologies responsible for iatrogenic spinal cord injury in patients admitted at a dedicated spinal cord Rehabilitation Centre. To study the prognosis of these patients in terms of neurological and functional outcomes for a period of 2 years. she procedure Methodology: This study analyzed al the SCI admissions to rehabilitation center over a duration of 4 years. These patients were followed at 6 weeks, 1 year and at 2 years post the injury. The patients were assessed as per the ASIA Scale for the neurological outcomes and as per the SCIM version 3 for the functional outcomes. Results: Out of 528 admissions, 42 patients were reported to have Iatrogenic SCI. The most leading cause of deterioration in our study was ischemic insult to the cord after vascular surgeries like Aneurysm, AV malformation, Aortic dissection and AV fistula repair (8 cases), the 2^nd most common cause was after an inadequate decompression (6 cases), 3^rd was mechanical pressure due to post-op haematoma or a pseudomenindocele (5 cases), 4^th being implant related (3 cases) and indirect cord manipulation as a result of deformity correction in scoliosis/kyphosis patients (3 cases). 1 out of the 3 patients did show intra-op signal loss on Neuro-monitoring. 2 patients had episodes of intra-op and post-op hypotension. 16 cases in our series didn’t have an identifiable cause but a couple of cases showed post-op high signals on T2 weighted MRI scan, suggestive of a vascular insult as a result of sudden decompression and 1 patient deteriorated after post-op infection, therefore an infective emboli could well be attributed as a probable cause. The pre-op Neurological status (AIS Grade) of these patients were 22 Intact, 16 Grade D, 3 Grade C, and 1 Grade B. Immediately after the surgical intervention their AIS grading were 7 Grade A, 6 Grade B, 21 Grade C and 8 Grade D. At 2-yrs follow-up after rehabilitation, 17 patients started mobilizing, 22 were wheelchair bound and could not walk and 3 died. 22 patients were intact before they underwent the surgery and 16 patients were AIS D pre-op. The SCIM scores for these patients improved from a mean of 30.10 (SD 19.56) to 59.09 (SD 23.62) at 2 years. Conclusion: The incidence of Iatrigenic SCI is higher than it is reported. There is a dire need of epidemiological studies to quantify these injuries and follow them up to see the prognosis of these patients in terms of neurological and functional outcomes. Also comparing Iatrogenic SCI patients with traumatic Spinal cord injury patients as a control will give a better understanding about the prognosis of these injuries.

89

P601: Influence of Severity and Level of Injury on the Occurrence of Secondary Complications During the Chronic Stadium of Traumatic Spinal Cord Injury: A Systematic Review

Charlotte Adegeest ¹ , Jort van Gent ¹ , Marcel Post ² , Janneke Stolwijk ² , Peter Vandertop ³ , Cumhur Oner ⁴ , Wilco Peul ¹ , and Valerie ter Wengel ⁵

¹ Leiden University Medical Center, Neurosurgery, Leiden, The Netherlands

² Rehabilitation center De Hoogstraat, Utrecht, The Netherlands

³ Amsterdam University Medical Center, Neurosurgery, Amsterdam, The Netherlands

⁴ University Medical Center Utrecht, Neurosurgery, Utrecht, The Netherlands

⁵ Haaglanden Medical Center Westeinde, Neurosurgery, The Hague, The Netherlands

Introduction: Secondary health conditions (SHCs) are long-term complications that frequently occur due to traumatic spinal cord injury (tSCI). This study investigated the associations between the severity and level of injury and the occurrence of SHCs. Material and Methods: Literature searches were conducted in PubMed and Embase. Studies on SHCs in individuals with tSCI published after 1990, containing at least 75 percent traumatic SCI and a minimum of ten participants were included. PRISMA guidelines were followed. Results: Forty-five studies were included. Reported SHCs were respiratory, gastrointestinal, musculoskeletal, urogenital, endocrinal disorders, cardiovascular diseases, pain, pressure ulcers and autonomic dysreflexia. In most studies, patients with motor-complete tSCI had a significantly increased occurrence of SHCs in comparison to motor-incomplete tSCI, such as pulmonary infections, neurogenic bowel dysfunction, urinary tract infections, renal stone formation, heterotopic ossification, pressure ulcers, and autonomic dysreflexia. Contrarily, an increased prevalence of pain was seen in individuals with motor-incomplete injuries. In addition, a higher occurrence of pulmonary infections, spasticity and autonomic dysfunction were seen in individuals with tetraplegia. People with paraplegia more commonly suffered from hypertension and pain. Conclusion: Overall, individuals with a motor-complete tSCI have an increased risk to develop multiple SHCs during the chronic stage of tSCI in comparison to motor-incomplete tSCI patients. Additional monitoring is recommended in individuals with motor-complete tSCI during the rehabilitation and chronic phase of tSCI, focused on early detection and prevention of SHCs in this population.

135

P602: The Current Status of Spinal Posttraumatic Deformity: A Systematic Review

Erin De Gendt ¹ , T.F.G. Vercoulen ¹ , Andrei Joaquim ² , W Guo ³ , Emiliano Vialle ⁴ , Gregory Schroeder ⁵ , Klaus Schnake ⁶ , Alexander Vaccaro ⁵ , Lorin Michael Benneker ⁷ , Sander Muijs ¹ , and Cumhur Oner ¹

¹ UMC Utrecht, Orthopedics, Utrecht, The Netherlands

² State University of Campinas, Neurosurgery, Campinas, Brazil

³ Sun Yat-sen University, Orthopedics, Guangzhou, China

⁴ Cajuru Hospital, Orthopaedics, Curitiba, Brazil

⁵ Rothman Institute, Thomas Jefferson University, Orthopaedic Surgery, Philadelphia, USA

⁶ Schön Klinik Nürnberg Fürth, Fürth, Germany

⁷ Inselspital, University Hospital Bern, Bern, Switzerland

Introduction: Some degree of deformity is common after traumatic spinal fractures. However, there is a high variation in the definition and indications for surgical treatment for SPTD. The lack of consensus about the definition of ‘clinically relevant SPTD’ limits the possibilities to compare different treatments and prognostic factors involved. The aim of this review is to systematically analyze the definitions and descriptions used in literature in order to support the development of a uniform and comprehensive definition of ‘Spinal Posttraumatic Deformity (SPTD)’. Material and Methods: This review is registered in PROSPERO. A literature search in Pubmed, Embase, Scopus, Global Clinical Trial Data, Cochrane library, SUDOC, Red de Revistas Científicas de América Latina y el Caribe, España y Portugal, eLibrary.ru, J-Stage and CNKI.net was performed using the search terms “kyphosis” AND “posttraumatic” and its synonyms. No languages were excluded. Articles were included when an original definition or a description of SPTD (Patient factors, Radiological outcomes, Patient Reported Outcome Measurements and Surgical indication) was present the article was included. The retrieved articles were assessed for methodological quality and the presented data was extracted. Results: 46 articles met the inclusion criteria. ‘Symptomatic SPTD’ was mentioned multiple times as an entity, however any description of ‘symptomatic SPTD’ was not found. Pain was mentioned as a key factor in SPTD. Other patient related parameters were (progression of) neurological deficit, bone quality, age, comorbidities and functional disability. Various ways were used to determine the amount of deformity on radiographs. The amount of deformity ranged from not deviant for normal to >30˚. Sagittal balance and spinopelvic parameters such as the Pelvic Incidence, Pelvic Tilt and Sacral Slope were taken into account and were used as surgical indicators and preoperative planning. The Visual Analogue Scale for pain and the Oswestry Disability Index were used mostly to evaluate surgical intervention. Conclusion: A clear-cut definition or consensus is not available in the literature about clinically relevant SPTD. Our research acts as the basis for international efforts for the development of a definition of SPTD. Follow-up steps will be setting up a Delphi-study in the Spine community to create a consensus definition of SPTD.

161

P603: Quality of Care Indicators in Individuals With Traumatic Spinal Cord Injury: A Scoping Review

Vafa Rahimi-Movaghar ^1,2 , Sepehr Khosravi ^1,2,3 , Amirmahdi Khayyamfar ^1,3 , Milad Shemshadi ^1,3 , Masoud Pourghahramani Koltapeh ^1,3 , Mohsen Sadeghi-Naini ⁴ , Zahra Ghodsi ¹ , Farhad Shokraneh ⁵ , Mohadeseh Sarbaz Bardsiri ¹ , Pegah Derakhshan ^1,3 , Khalil Komlakh ⁴ , Alexander Vaccaro ⁶ , Michael Fehlings ^7,8 , James Guest ⁹ , and Vanessa Noonan ¹⁰

¹ Sina Trauma and Surgery Research Center, Tehran University of Medical Science, Tehran, Iran

² Universal Scientific Education and Research Network (USERN), Tehran, Iran

³ Student Research Committee, School of Medicine, Iran University of Medical Sciences, Tehran, Iran

⁴ Neurosurgery Department, Imam Hossein Hospital, Shahid Beheshti University of medical science, Tehran, Iran

⁵ King's Technology Evaluation Centre (KiTEC), London Institute of Healthcare Engineering, School of Biomedical Engineering and Imaging Sciences, Faculty of Life Sciences and Medicine, King's College London, London, United Kingdom

⁶ Department of Orthopedics and Neurosurgery, Rothman Institute, Thomas Jefferson University, Philadelphia, USA

⁷ Division of Neurosurgery, Department of Surgery, University of Toronto, Toronto, Canada

⁸ Division of Neurosurgery, Toronto Western Hospital, University Health Network, Toronto, Canada

⁹ University of Miami Miller School of Medicine, Neurological Surgery, Miami, USA

¹⁰ Praxis Spinal Cord Institute, Vancouver, Canada

Introduction: Traumatic spinal cord injury (TSCI) has an annual incidence of 40-80 per million people. Well defined and valid Quality of Care Indicators (QoCI) can help improve TSCI care by establishing parameters that clinicians, healthcare managers, and policymakers can monitor and report. This study aims to identify a practical and reproducible approach to organize QoCI in individuals with traumatic spinal cord injury (TSCI). Material and Methods: For this scoping study, a comprehensive literature review was conducted in the Cochrane Central Register of Controlled Trials (CENTRAL) (Date: May 2018), MEDLINE (1946 to May 2018), and EMBASE (1974 to May 2018). Two independent reviewers performed title/abstract screening and data extraction into a predefined form. We included studies with no language restriction containing at least one quality of care indicator for individuals with traumatic spinal cord injury. We excluded case series with less than ten cases, as well as studies on animals. We excluded studies in which rehabilitation included new technologic instruments and devices (such as robotic devices for the assistance of the patient). Each potential indicator was brought into an online focus group discussion to define its categorization (healthcare system structure indicators, medical process indicators, and TSCI related outcomes), definition, survey options, and scale. Results: A total of 87 indicators were identified from a review of 60 studies screened using our eligibility criteria. These 60 studies contain 21,574 cases. Overall, 37 indicators appraised the healthcare system structure, 30 evaluated medical processes, and 20 included TSCI related outcomes. The healthcare system structure included the impact of cost in the acute phase of hospitalization and rehabilitation, staff- and patient-perception of treatment, care, and facilities. The healthcare system structure also includes transfer time from injury to surgery, waiting time in the emergency department, time spent in a second hospital, and transfer time to a spine center. The medical processes included targeting physical activities for improvement of health-related outcomes and complications, pain and fatigue assessment per patient per year, use of telemedicine during patient care, pressure ulcer prevention, and psychological assessments, changes in motor score, functional independence, readmission rates for complications (also defined as discharge efficiency measured as readmission/discharge) are reported as individuals with TSCI related outcomes indicators. Indicators related to the mental wellness of individuals with TSCI (such as social participation and frequency of behavioral incidents) are also reported as outcome indicators. Conclusion: Indicators of quality of care in the management of individuals with TSCI are important for health policy strategists to standardize healthcare assessment, for clinicians to improve care; and for data collection efforts, including registries. These indicators could be adjusted to different clinical settings.

191

P604: Protocol for Evaluation of Quality of Care in Traumatic Spinal Column and Cord Injuries (TSCI/SCI) in Iran

Vafa Rahimi-Movaghar ^1,2,3,4,5,6 , Zahra Ghodsi ¹ , Mohsen Sadeghi-Naini ⁷ , Bizhan Aarabi ⁸ , Mohadeseh Sarbaz Bardsiri ¹ , Zahra Azadmanjir ^1,9 , soheil saadat ¹⁰ , Ali Haghnegahdar ^11,12 , Esmail Fakharian ¹³ , Gerard O'reilly ^14,15,16 , Vanessa Noonan ¹⁷ , and Alexander Vaccaro ¹⁸

¹ Sina Trauma and Surgery Research Center, Tehran University of Medical Sciences, Tehran, Iran

² Brain and Spinal Cord Injury Research Center, Neuroscience Institute, Tehran University of Medical Sciences, Tehran, Iran

³ Department of Neurosurgery, Shariati Hospital, Tehran University of Medical Sciences, Tehran, Iran

⁴ Universal Scientific Education and Research Network (USERN), Tehran, Iran

⁵ Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran

⁶ Visiting Professor, Spine Program, University of Toronto, Toronto, Canada

⁷ Neurosurgery Department, Imam Hossein Hospital, Shahid Beheshti University of medical science, Tehran, Iran

⁸ Department of Neurosurgery, University of Maryland School of Medicine, Baltimore, USA

⁹ Department of Health Information Management, School of Allied Medical Sciences, Tehran University of Medical Sciences, Tehran, Iran

¹⁰ Department of Emergency Medicine, University of California Irvine, Irvine, USA

¹¹ Department of Neurosurgery, Shiraz University of Medical Sciences, Shiraz, Iran

¹² Trauma Research Center, Shahid Rajaee (Emtiaz) Trauma Hospital, Shiraz University of Medical Sciences, Shiraz, Iran

¹³ Department of Neurosurgery,Trauma Research Center,Kashan University of Medical Sciences (KAUMS), Kashan, Iran

¹⁴ Emergency and Trauma Centre, Alfred Health, Melbourne, Australia

¹⁵ School of Public Health & Preventive Medicine, Monash University, Melbourne, Australia

¹⁶ National Trauma and Research Institute, Alfred Health, Melbourne, Australia

¹⁷ Praxis Spinal Cord Institute, Research and Best Practice Implementation, Vancouver, Canada

¹⁸ Department of Orthopedics and Neurosurgery, Rothman Institute, Thomas Jefferson University, Philadelphia, USA

Introduction: The value of health care is defined as the quality of care (QoC) in a particular condition per cost of the service provided to achieve an outcome. To formulate, we need to know how patients use healthcare facilities during the diseases/injury care, how much each healthcare facility cost, and what extent of the facility is available. This study aims to define the quality of care indicators for TSC/SCI; estimate the real demographics of TSC/SCI in Iran, including the injury characteristics, medical interventions in pre-hospital and hospital phases, outcome, and rehabilitation services; and estimate the overall cost of TSC/SCI in this three-year study. Material and Methods: To evaluate our health care system on TSC/SCI patient care, we have designed a scoping review to summarize all QoC indices and will draw a summarized table. We will present each indicator to an expert panel to acquire their opinion and validate the questionnaire by focus group discussion which will be reviewed and approved by three agents from police, judiciary, and parliament. We will collect primary data of TSC/SCI patients from the national spinal column/cord injury registry of Iran (NSCIR-IR), a not-for-profit hospital-based registry to register patient data prospectively. It was designed by a panel of national and international experts. We include all 1600 cases registered in the NSCIR-IR from nine centers of eight cities across the country. NSCIR-IR has already recorded the pre-hospital and hospital data of TSC/SCI patients in a 351 variables questionnaire and assessed system managing from the scene to hospital discharge. After data entry and submission of patients recorded in the system by registrars, two independent quality control reviewers will check the completeness, consistency, and accuracy of data. To extend our evaluation, we will implement a three-year follow-up cohort study of the registered patients and data will be gathered by contact calls on an annual basis. Data on the insurance type and cost of admission will be gathered from the hospital discharge unit. Since the NSCIR-IR is an ongoing registry, newly added patients will be followed up until the end of the third year of the study. Since we have implemented NSCIR-IR in eight different cities of Iran, we already have registrar nurses from different local cultures that provide valuable communication potential for included patients. We follow two methods to assure consistency: 1) the software alerted and rejected all the entries which are not consistent with the hierarchy of dates or semantic relationship of variables and data according to patient’s condition. 2) Then data will be checked to ensure that there is no other inconsistency that could not be identified or prevented by the software. We will use the evidence from the present study to prepare a national standard of care guideline for TSC/SCI patients and guide the health policymakers to design and implement interventions to improve the QoC in this regard. Results: This is protocol and does not have a final result or conclusion at the moment. Conclusion: Conclusion is not available at the moment.

257

P605: 360 Degrees Stabilization-AO Spine Classification for Traumatic Fractures

Orlin Pavlov ¹ , Nikolay Mirchev ¹ , Alexa Ruiz ¹ , and Robert Behr ¹

¹ Klinikum Fulda, Department of Neurosurgery, Fulda, Germany

Introduction: The patients with traumatic fractures are a growing group of patients, who undergo a spinal fusion because of the huge leap in the understanding of spinal instability. In general a dorsal fusion is aimed with or without decompression to achieve a fusion. With the complexity of some fractures, it sometimes required to perform a 360 degrees stabilisation of the spine to achieve fusion. Methods: In our series, there were 8 patients, who underwent a 360 degrees stabilisation because of a traumatic fracture. The classification from AO Spine was used: 1 A2; 3 A3; 2 A4; 1 B1; 1 B2 fractures. Regarding the indication for 360 degrees stabilisation, the co-morbidities of the patients played a crucial role. 2 patients had osteoporosis and 2 other patients had m. Morbus Bechterew and one patient had undergone a hysterectomy and had m. Parkinson. When taking in consideration the ventral fusion, several factors played an important role: type of the fracture, kyphosis or lordosis, localisation of the fracture and patient’s compliance. Both patients with m. Bechterew underwent 360 degrees stabilisation because of fractures located in the cervicothoracic junction. Results: All patients underwent a 360 degrees stabilisation of the spine whether in single or double surgical intervention. No surgical complications were observed postoperatively. Conclusions: The indications for 360 degrees stabilisation of the spine are based on multiple factors, including: patient’s age, co-morbidities, type of the fracture, compliance of the patient and patient’s personal choice. The 360 degrees stabilisation is safe and feasible method to treat complex spine fractures.

314

P606: Prevalence of Secondary Complications in Patients With Traumatic Spinal Cord Injuries at a North Tanzanian Referral Hospital

Mubashir Jusabani ¹ , Sakina Rashid ² , and Marieke C.J. Dekker ³

¹ Kilimanjaro Christian Medical Centre, Department of Orthopedics and Trauma Surgery, Kilimanjaro, Tanzania

² University of Cape Town, Division of Neurosurgery, Cape Town, South Africa

³ Kilimanjaro Christian Medical Centre, Department of Internal Medicine, Kilimanjaro, Tanzania

Introduction: To describe the prevalence and nature of secondary complications in patients with Traumatic Spinal Cord Injuries (TSCIs) at Kilimanjaro Christian Medical Centre. Material and Methods: The medical records of 125 patients with TSCIs from January 2011 to December 2015 were retrospectively reviewed. Demographic data and clinical information detailing injury characteristics and in-ward progress were recorded for each patient. Results: With an average age of 39.9 years, the study group had a preponderance of males (n = 107, 85.6%). A total of 83 (66.4%) patients developed secondary complications following admission. The most common complications were stool retention in 32 (25.6%), pressure sores in 29 (23.2%) and urine incontinence in 29 (23.2%); other complications included intestinal obstruction (2.4%) deep venous thrombosis (.8%), flexion contractures (.8%) and heterotrophic ossification (.8%). The length of stay in the wards was significantly longer for patients who developed secondary complications. Mortality rates were also higher in this subset of patients. Conclusion: A strained healthcare budget in a low-income country manifests in the high secondary complication rate. TSCI patients in a low resource setting have a grim prognosis, further compounded by the occurrence of preventable secondary complications.

324

P607: Follow-Up After Operatively Treated Isolated Spine Trauma

Ekamjeet Dhillon ¹ , Celeste Tavolaro ¹ , Richard Bransford ¹ , Carlo Bellabarba ¹ , and Haitao Zhou ¹

¹ Harborview Medical Center, Orthopaedics and Sport Medicine, Seattle, USA

Introduction: Trauma patients have poor follow up. The current rate of follow up of patients who have sustained spine trauma is unknown. The purpose of this study is to determine the rate and length of follow-up care for patients with isolated spine trauma who underwent instrumented fixation. Material and Methods: All patients admitted to a level I trauma center with isolated spine injuries without spinal cord injury were retrospectively identified from the case log of one attending surgeon over a 5-year period. A total of 74 patients who sustained isolated spine trauma and underwent instrumented fixation were identified. Demographic data, home zip code, employment status, insurance type, workers compensation, tobacco use, illicit drug use, marital status and living arrangement were documented. Length of follow up and rate of follow-up were collected. The last clinic visit was reviewed to determine whether patient completed follow-up. Results: A total of 74 patients met inclusion criteria. Overall follow up length was 176 ± 154 days, median follow up length was 128 days. Follow-up rates at 3 months, 6 months, and 1 year were 65%, 39%, and 20%, respectively. About 14% never showed up for any follow-up appointments. Over half of the patients, (68.9%, n = 51) failed to return for a clinical follow-up when requested. Younger age, uninsured and medicaid patients, illicit drug use were risk factors for noncompliance with clinical follow-up (P < .05). Conclusion: Patients who have sustained isolated spine trauma and undergone instrumented fixation have low follow-up compliance. This is far from an ideal clinical research world with at least one-year follow-up desirable for most patients. Future studies should illicit the reasoning for loss of compliance, especially after the initial appointment as only 14% fail to show up for their initial visit whereas 69% of patients were lost to follow-up despite being requested to return to clinic.

352

P608: Two- Year Experience of Spinal Gunshot Injuries in México: A Single Center Experience

Francisco Ismael Villarreal-García ¹ , Oscar Armando Martínez Gutiérrez ¹ , Pedro Martín Reyes Fernández ¹ , Luis Antonio Saavedra Badillo ¹ , and Victor Manuel Peña Martínez ¹

¹ Hospital Universitario "José Eleuterio González" Monterrey, Nuevo León México, Servicio de Ortopedia y Traumatología. Módulo de Cirugía de Columna, Monterrey, Mexico

Introduction: Gunshot-induced spinal cord injuries have become increasingly frequent in the civilian population. Globally, these injuries have become a public health problem because they significantly impair a patient’s quality of life, functional status, and social independence. Due to the recent increase in the admission of patients with spinal gunshot injuries in our hospital (level III trauma center), the purpose of this study is to report epidemiological and clinical data of the patients that were admitted with spinal gunshot injuries. Material and Methods: An observational, retrospective study in which patients who had a spinal injury secondary to a gunshot wound that were admitted to our hospital (level III trauma center) from July 2018 through July 2020 were included. Demographic and clinical data including age, gender, civil status, occupation, level of injury (cervical, thoracic or lumbar), degree of neurological impairment at admission, associated injuries, treatment established, length of hospital stay and mortality rate were recorded. Results: In the years included in the study, a total of 503 fractures (spine and non-spine) secondary to gunshot wounds were admitted to our hospital, of which 55 (10.93%) consisted of vertebral fractures. Fifty-five patients were admitted to our hospital with gunshot injuries to the spine (with and without neurological deficit) from July 2018 through July 2020. No patients were excluded from the study. A total of 55 patients were included in the study, of which 50 patients (90.9%) were men and 5 female patients (9.09%). The average age was 30.2 years. Three patients died during hospitalization representing a mortality rate of 5.45%. The causes of death were multi-system organ failure. The thoracic spine had the highest frequency of injury in our series with a total of 26 (47.27%) injuries, 25 (45.45%) lumbar spine injuries, 3 (5.45%) cervical spine injuries and 1 (1.81%) sacral injury. Thirty patients (54.53%) had neurological deficits at admission of which 2 (3.63%) were cervical spine injuries, 18 (32.72%) were thoracic spine injuries and 10 (18.18%) were lumbar spine injuries. The patient who had a sacral injury had no neurological injury. Of the 30 patients with neurological injury, 29 had a complete injury (ASIA A) and only one patient arrived with an incomplete injury (ASIA B). The average hospital length of stay was 11.4 days, being the longest stay for patients with thoracic spine injuries with an average of 12.96 days. Cervical spine injury patients had an average of 5.33 days, patients with lumbar spine injuries had an average length of stay of 10.8 days and the only patient we had from sacral spine injury lasted 4 days in the hospital. Conclusion: Spinal gunshot injuries are associated with significant sequelae, requiring long and costly treatments. This study obtained one of the highest incidences of gunshot injuries to the spine reported in the literature. Based on our data they are more prevalent in the male population with an average age of 30.2 years old. The highest incidence of spinal gunshot injuries was at the thoracic spine and the most frequent associated injury was hemopneumothorax.

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P609: A Comparison of Medium Viscosity Bone Cement and High Viscosity Bone Cement for Osteoporotic Vertebral Fracture

Sasa Rapan ¹ , Vjeran Rapan ¹ , Domagoj Rapan ¹ , Vjekoslav Kolarevic ¹ , and Egon Biuk ¹

¹ Clinical Hospital Osijek, Orthopedic Surgery, Osijek, Croatia

Objective: This study aimed to compare the success of the vertebroplasty with medium- and high-viscosity cements, the level of pain reduction and the frequency of complications. Study Design: The study was organized as a cross-sectional. Thirty patients were included, 26 of whom were women and 4 men. Materials and Methods: Data were obtained from the medical history of patients with vertebral body fractures who underwent vertebroplasty in the last 6 months at the Department of Orthopedics and Traumatology of the Clinical Hospital Center Osijek. The data observed included age, gender, localization and pain level pre- and post-surgery according to visual-analogue scale (VAS), as well as radiological changes on the operated segment, and extracorporeal cement leakage. Results: Of the total of 30 patients, 4 (13.3%) were male and 26 (86.7%) were female. In terms of localization, 34 (73.9%) patients had a lumbar spine fracture and 12 (26.21%) subjects had a thoracic spine fracture. The majority of patients, 13 (43.3%), had a fracture at the L1 vertebra, 33.3% had a fracture at L2, while 26.7% had a fracture at L3. In the thoracic region, the most common fracture site for 23.3% of patients was Th12. There is no significant difference in fracture location with respect to the application of medium- or high-viscosity cement. All interventions were performed from Th9 to L3. Pain levels measured by VAS before the surgery were 8 (interquartile range 8 to 9), and after the surgery 2 (interquartile range 1 to 3 for MVC and 1 to 2 for HVC). There was no extracorporeal leakage with HVC administration, and only 27.27% was observed with MVC. There were no significant clinical complications. Conclusion: Pain reduction via vertebroplasty is achieved equally successfully with both used cement viscosities, but cement leakage is significantly lower with the use of HVC and thus makes it a safer option.

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P610: Pediatric Spinal Trauma- An 11-Year Review in a Single Level 1 Trauma Center

Alexandra Satanovsky ¹ , Sharon Eylon ² , Leon Kaplan ¹ , and Josh Schroeder ¹

¹ Hadassah Medical Center, Orthopedic Surgery, Jerusalem, Israel

² Alyn Rehabilitation Hospital for Children & Adolescents, Jerusalem, Israel

Introduction: Pediatric spinal cord injury (SCI) is a rare condition, with reported incidence of 26.9 per million children, as compared to pediatric cervical fractures, reported to have an incidence of 2.9% of all trauma injuries. Pediatric SCI is variable both in presentation and outcome. The literature is scant. We here present a series of children with pediatric SCI. Material and Methods: A retrospective review of the trauma registry of a level 1 trauma center between 2006 and 2017 was performed. All children (aged 0-18) with a SCI were collected. Demographic data, injury data including mechanism, injury severity score, additional injuries and level of spinal injury at time of arrival was obtained. Data on surgical and non-surgical intervention, length of hospital stay, discharge destination and long term follow up was extracted. Results: 30 children were identified with SCI. Most were male (24/30), mean age of 13.9. Mean ISS was 32.93. Mechanism of injury was MVA (17), contusion (5), fall from height (4), penetrating (3) and blast injury (1).The associated injuries were abdominal (17), chest wall and lung (24), brain (10). Fractures were noted in 23 cases (pelvic, skull, extremity), and vertebral fractures were noted in 17 children. Mean length of hospital stay was 23.77 days. level of injury was cervical in 21, thoracic 5, lumbar 4 in with initial ASIA scores of A in 11 (37.95%), B in 8 (27.59%), C in 4 (13.79%), D in 6 (20.69%). Latest ASIA score was A for 8.33%, B for 12.5%, C for 20.83%, D for 33.33% and E for 25%. Mean delta in ASIA score was 1.67 points, with significant improvement is 8 children. The mean follow-up is 26 months, obtainable for 26 patients. Conclusion: Spinal cord injury is a rare and grave condition, it is rarely an isolated condition, and usually presents with multiple injuries. The recovery course is long but in many of the children an improvement can be seen.

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P611: Hyperextension Fractures in Spondylosis and Ankylosing Spine Disorders: Injury Profile & Outcomes of Treatment

Juan Ignacio Cirillo ¹ , Ignacio Farias ¹ , Jose Vicente Ballesteros ¹ , Marcos Gimbernat ¹ , Gabriel Hernández ¹ , and Felipe Turner ²

¹ Hospital del Trabajador, Equipo de Columna, Santiago, Chile

² Hospital del Trabajador, Traumatología, Santiago, Chile

Introduction: Hyperextension distraction type injury of the spine (B3 AOSpine) are uncommon injuries, usually reported in patients with rigid spine such as Diffuse Idiopathic Skeletal Hyperostosis (DISH) or Ankylosing Spondylitis (AS). There are currently no reports describing these lesions in patients with spondylosis and comparing them with rigid spine patients. In this study, we want to compare demographic metrics, injury profile, clinical and radiographical outcomes, results of surgical treatment and complications of patients between spondylosis and rigid spine in patients suffering from B3 AOSpine fractures. Material and Methods: This is a case series study design. Patients diagnosed with B3 AOSpine fractures between 2012 and 2020 were identified. A retrospective analysis of Clinical and surgical data was performed. IBM SPSS version 23.0 was used for data entry and statistical analysis. Similarities between patients with AS, DISH and spondylosis were evaluated by Fisher’s exact test. Results: Of the 22 patients, 10 patients had DISH (45.4%), 3 AS (13.6%) and 9 spondylotic changes (40.9%) without DISH or AS. In 4 subjects (18.1%) the fractures were in the subaxial cervical spine, 6 thoracic (27.2%), 10 thoracolumbar (45.4%) and 2 lumbar (9.09%). The mean age with DISH and spondylosis was 59.2 years (39-79), higher than the mean age of the group with AS 43.3 (39-46 years). 72.7% of the patients presented associated injuries and 36.6% had spinal fractures in another segment (4 in DISH and 4 in spondylosis). 44.4% and 30.7% of the patients with spondylosis and rigid spine had spinal cord injury, respectively. 63.6% presented postoperative complications. The mortality rate was 13.6%. No spondylotic and 3 DISH-AS patients had low energy mechanism but there was no significatively association (P .22). On average, the instrumented levels were 4 (range, 2-6), achieving a fusion rate of 90.9% in all groups. Conclusion: In elderly patients with spondylotic spine and high-energy accidents, we should suspect B3 AOSpine fractures, even in the absence of DISH or EA, and rule out associated injuries, fractures in other vertebral segments, and acute spinal cord injury. All patients with spondylotic changes suffered high-energy accidents, while all low-energy mechanisms were in patients with DISH or AS. The four level instrumentation achieved an effective fusion rate in all patients. Due to the increased life expectancy and associated spondylosis, hyperextension distraction injuries are not unique in rigid spines.

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P612: Coccigectomy. Diagnosis and Treatment: Presentation of 35 Cases

Gilberto Gardea Loera ¹ and Gilberto Gardea Ramirez ²

¹ Hospital Star Medica Chihuaua, Neurosurgery, Chihuahua, Mexico

² UACH, Medical School, Chihuahua, Mexico

Introduction: To present 35 patients who underwent coccygeal resection as well as diagnostic measures, surgical treatment and emphasis is placed on differential diagnosis with lumbo-sacral spine pathology. Material and Methods: 35 patients, 29 women and 6 men, 15 with low back pain irradiated to pelvic members, sign of negative Lasegue and all with coccydynia from 3 months to 5 years of evolution. The age range was from 13 to 76 years. The criteria for patient selection were: 1.-Failure of conservative treatment for a minimum period of 3 months, 2.-Pain on coccygeal palpation, 3.-Radiological instability of the coccyx (intermittent dislocation or hypermobility of the coccyx). All patients underwent coccygeal resection. Thirty percent of the patients were operated under general anesthesia and remained in the hospital for one day during the first three years of the study. The rest of the patients were operated using epidural block as outpatient surgery. All were given prophylactic antibiotics. The average time of surgery was 30 minutes. All patients have postoperative follow-up ranging from 1 month to 11 years. Results: The average of definitive improvement was 4 to 8 months with ranges from 1 month to 1 year. 31 patients had excellent evolution, 3 patients had good evolution (95%), and 1 patient had poor evolution. 9 patients had superficial and partial dehiscence of the wound and in 3 there was data of infection improving totally with antibiotic and daily cleaning of the wound. Conclusions: Therefore, coccygeal resection has excellent results in patients with pain on palpation of the coccyx and especially when there is instability of it. It is necessary to keep in mind in patients with low back pain the coccyx injuries as a differential diagnosis. The prophylactic antibiotic is clearly indicated. The treatment is effective from one month on and can take up to 1 year.

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P613: Bilateral Facet Dislocation Without Fracture at the Lumbosacral Joint in a Pediatric Patient. A Case Report and Review of the Literature

Maria Celeste Zamora ¹ , Marcelo Alejandro Valacco ¹ , Mariano Servidio ¹ , and Felix Imposti ¹

¹ Complejo Medico Policial Churruca Visca, Buenos Aires, Argentina

Introduction: Traumatic lumbosacral dislocation with or without fractures are infrequent injures, with only a few cases reported in literature in the pediatric population. It results from high-energy trauma. Surgical treatment algorithm is not defined, but open reduction and internal fixation are often necessary because of a three-column involvement. We describe a case of bilateral facet dislocation without fracture at the lumbosacral joint in a 9-year-old boy with a thorough review of the existing literature. Material and Methods: A 9-year-old boy was admitted to the emergency department, after having been buried beneath a wall. He had a palsy in his right foot in dorsiflexion without sensory and sphincters deficit. A computed tomography scan revealed anterior grade II spondylolisthesis, with bilateral facet dislocation without fracture. Magnetic resonance imaging showed a traumatic rupture of the fibrous annulus of the L5-S1 intervertebral disc. The patient was admitted and underwent an open posterior approach at 48 hours, bilateral facetectomies, decompression, reduction and fixation with pedicle screw at L5 and S1 and posterolateral lumbar fusion with autologous bone from the posterior iliac crest. No changes were observed in electromyogram. Results: At 10-months follow-up, the patient is asymptomatic and the palsy resolved completely. Radiologic showed an unaltered reduction and a reliable fusion. Conclusion: Traumatic spine injury is rare in the pediatric population. The literature is scarce on this type of injury in children. Careful clinical examination and detailed imaging assessments must be done for an appopriate diagnosis and treatment of this rare type of injury.

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P614: Nature of Injury of Domestic Violence and Abuse Among Orthopedic Practice During Covid19

Santosh-Kumar Bashyal ^1,2,3 , Bipina Pandey ⁴ , Dristi Bashyal ⁵ , Mandir Khatri ³ , and Nabin Pahari ⁶

¹ Devdaha Medical College Research Institute/Vasundhara-Pramanand Worldwide Research Foundation, Orthopedic/Spine, rupandehi, Nepal

² Devdaha Medical College Research Institute /Vasundhara-Pramanand Worldwide Research Foundation, Orthopedic/Spine, Rupandehi, Nepal

³ Devdaha Medical College, Rupandehi, Nepal

⁴ People Dental College, Kathmandu, Nepal

⁵ National Cancer Hospital, Kathmandu, Nepal

⁶ Devdaha Medical College, Rupandehi, Nepal

Introduction: In Covid pandemic Orthopedic trauma caring seeking to Emergency department might be less but the nature and mode of injury are different. Due to home isolation partners violence, abuses are seen which caused orthopedic service help. Screening about abuse and violence is very important to all the patients seeking orthopedic care due to trauma or domestic injury. The aim of this study help find the nature and mode of injury due to domestic violence and abuse(DVA) among orthopedic practices. Material and Methods: A retrospective study was done from March 25, 2020 to 17 Aug 2020 data based entry taken from ER,OPD and Operation room. Physical assault, domestic violence questionnaire were checked and screened done. Each cases were phoned and ask about the condition after violence. Number of department involved in domestic violence cases care and progression were evaluated. Results: Total number of cases seeking for orthopedic care were 343 during lockdown period of covid-19.Among them 38 need operation treatment like open reduction, close reduction, tendon repair, Hairware failure. 5 cases after physical screening, police department information was found to be domestic violence and abuse seeking for orthopedic care. Among them 3 were Female and 2 male. 2 had the history of physical violence in past. Stab injury from sickle, knife was common weapon used. Psychiatric illness, depression, loss of jobs, economic crises were the major elements for this violence. There was no self inflicted injuries. Among them one case was security guard of same hospital having shaft of ulnar fracture with HbsAG positive was treated conservative. Rest of other cases had injury over chest, ribs, head, shoulders which was found to be soft tissue injury. One case had cut injury over the thumb, managed with suture at ER. None used operative intervention. Among orthopedic practice cases having domestic violence seeking orthopedic care were less then .01 pc. All the cases of DVA were done mental health consultation. Conclusion: It is important that Early intervention and referral to a DVA advocate can prevent an worst situation with intense violence preventing life. All the Orthopedic care services should be screen for DVA and mental health consultation.

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P615: An Alternative Ergonomic Open Reduction Technique on Traumatic Lumbosacral Dislocation: A Technical Note With Case Illustration

Wendy Lee ¹ and Chung Chek Wong ²

¹ Sibu Hospital, Department of Orthopaedic Surgery, Sibu, Sarawak, Malaysia

² Sarawak General Hospital, Department of Orthopaedic Surgery, Kuching, Sarawak, Malaysia

Introduction: Traumatic lumbosacral dislocation remains an infrequent entity. Watson-Jones (1940) and Newman (1965) failed closed reduction and observed exacerbation of neurological deficits following traction. The crucial role of open reduction, first successfully reported by Samberg (1975) has thus been underscored. A wide array of open reduction manoeuvres, from operating table breaking hinge, laminectomy, clamps distraction, L4 extended instrumentation, to partial or total facetectomy have been portrayed with varying hurdle intensity and unresolved concord. We illustrate an ergonomic reduction technique utilizing surgical instruments not-more-than typically required that obviated facetectomy. Material and Methods: Posterior dissection on an acute case of lumbosacral dislocation (with L5 sacralization) following a lumberjack injury exposed bilateral naked S1 facet joints with L5 inferior articular process (IAP) tucked ventrally underneath. Readily available S1 screw insertion landmark therein permitted slight medialized entry, guiding for more in-line L5 screw placement. To disengage the dislocated facets, the intervertebral space was first jacked apart in a controlled manner using interpedicular screws distractor. This provided leeway for concave surface of Cobb elevator to enter in a "scoop-like" manner, moulding along the convex surface of L5 IAP. Cobb’s handle was further levered dorsally in a cranial-caudal direction to level the S1 facet. While holding the elevator in place, the distractor was substituted with compressor. Simultaneous compression and IAP cantilevering forces atop the S1 facet restored articular congruency. A single interbody cage fusion ensued the dejunking of torn dorsal ligaments via flavectomy and unilateral left partial L5 laminectomy. Results: A triad of L5 screws convergence—entered via Superior AP-Transverse Process intersection, indirect counter cephalad elevation of a straight rod tightened down to the caudal polyaxial screw heads, and final L5 screw-rod persuasion augmented the stability of facet reduction. Right and left L5 motor recovered from (0 to 2) and (2 to 3) at 48-hour postoperatively. At 6-month, patient regained normal S1 and left L5 motor while right L5 improved to 4. Sphincters control was preserved throughout. Fusion took place at 9 months. Conclusion: L5-S1 facet orientation resembles that of subaxial cervical in coronal plane. Its marked vertical sagittal inclination, however, articulated Watson-Jones’ (1940) remark in that the overall force of open reduction would not outweigh its initial external force, hence the increased risk of neurological deficit in closed reduction. While total facetectomy is hailed to ease reduction, concern of compromised stability at the expense of adjunctive biosynthetic osteoinductive usage, and 360-degrees fusion have been observed. Our technique adapted cervical facet open reduction manoeuvre and took to the advantage of multifaceted modern pedicle instrumentation alongside convenient incorporation of Cobb elevator. 3-column traumatic injury as such, distinctive from degenerative spondylolisthesis, calls for an ergonomic approach that preserves utmost posterior stabilising elements to attain fusion without sacrificing adjacent L4-5 motion segment.

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P616: Functional Outcome in Patients With Dural Arteriovenous Fistulae After Surgical Treatment

Isabel Hostettler ¹ , Vicki Butenschön ¹ , Bernhard Meyer ¹ , and Maria Wostrack ¹

¹ Klinikum rechts der Isar, Neurosurgical department, Munich, Germany

Objective: Spinal dural arterio-venous fistulas (SDAVF) are rare vascular pathologies. Degree of symptom improvement after surgery remains unclear. We evaluated surgically treated SDAVF patients for functional outcome and symptom improvement. Methods: Retrospective inclusion of consecutive patients treated surgically in our department between 2007 and 2019. We measured functional outcome using the McCormick Scale and modified Japanese Orthopaedic Association (mJOA) score. Results: We included 27 patients with a median follow-up of 8.8 months (IQR 27.8). Mean age was 61.8 years (SD 8.4), 40.7% were female. Most frequent location was the thoracic spine in 15 (55.6%) followed by lumbar in 8 (29.6%), cervical in 3 (11.1%) and sacral spine in one patient (3.7%). Most common presenting symptom was progressive myelopathy (24/27 patients, 88.9%). In all patients the SDAVF was completely resected, however 4 patients (14.8%) required a second surgery. Six patients (22.2%) deteriorated immediately after surgery with five recovering to baseline upon discharge. On discharge, presenting symptoms had improved in 17 patients (63%), 8/25 patients (32%) had a McCormick score of 1. Twenty (74.1%) continued to improve on follow-up. In total 23/27 patients (85.2%) improved. In the univariable analysis mJOA score on admission was associated with mJOA score on follow-up (coefficient .6, 95%CI .4-.81, P < .001), whereas age was inversely associated (coefficient -.1, 95%CI -.19-.01, P = .08). Conclusion: Untreated SDAVF leads to progressive myelopathy which may result in considerable disability. Surgical disconnection and resection provides a safe treatment option with low perioperative morbidity and excellent chances for symptom improvement or progression prevention.

Keywords

spinal dural arteriovenous fistula, myelopathy, surgery, functional outcome

1464

P617: Reliability Analysis of the AO Spine CROST (Clinician Reported Outcome Spine Trauma): A Tool to Evaluate and Predict Outcomes From Clinician's Perspective

Said Sadiqi ¹ , Cumhur Oner ¹ , and AO Spine Knowledge Forum Trauma ²

¹ University Medical Center Utrecht, Department of Orthopaedics, Utrecht, The Netherlands

² AO Foundation, Davos, Switzerland

Introduction: Besides a patient reported outcome measure, there is also need for a simple, reliable and quick to administer tool that is completed by the treating surgeons. It would formalize the most relevant clinical and radiological assessment parameters, and enables them to evaluate and predict the clinical and functional outcomes of spine trauma patients: the AO Spine CROST (Clinician Reported Outcome Spine Trauma). This study reports on the development of the tool as well as the results of an initial reliability study. Material and Methods: The AO Spine CROST was developed using an iterative approach of multiple cycles of development, review and revision including an expert clinician panel. Subsequently, a reliability study was performed among an expert panel who were provided with 20 spine trauma cases, administered twice with a four-week interval. The results of the developmental process were analyzed using descriptive statistics, the reliability per parameter using Kappa statistics, inter-rater rater agreement using Intraclass Correlation Coefficient (ICC), and internal consistency using Cronbach’s α. Results: The AO Spine CROST was developed and consisted of 10 parameters, 2 of which are only applicable for surgically treated patents (‘Wound healing’ and ‘Implants’). A dichotomous scoring system (‘yes’ or ‘no’ response) was incorporated to express expected problems for the short-term and long-term. In the reliability study, 16 (84.2%) participated in the first round and 14 (73.7%) in the second. Intra-rater reliability was fair to good for both time-points (κ = .40-.80 and κ = .31-.67). Results of inter-rater reliability were lower (κ = .18-.60 and κ = .16-.46). Inter-rater agreement for total scores showed moderate results (ICC = .52-.60) and the internal consistency was acceptable (α = .76-.82). Conclusion: The AO Spine CROST, an outcome tool for the surgeons, was developed using an iterative process. An initial reliability analysis showed fair to moderate results and acceptable internal consistency. Currently, further studies are being performed to test the tool in prospective studies. Once further validated, this tool has the potential to be used in daily clinical practice and for research purposes in order to create and contribute to evidence-based and patient-centered care.

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P618: Single-Centre Study Comparing Surgically and Conservatively Treated Patients With Myelon Herniation and Review of the Literature

Isabel Hostettler ¹ , Vicki Butenschön ¹ , Bernhard Meyer ¹ , and Mascha Wostrack ¹

¹ Klinikum rechts der Isar, Department of Neurosurgery, Munich, Germany

Background: Spinal cord herniation (SCH) is a rare cause of progressive myelopathy and Brown-Séquard-Syndrome. Objective: Evaluation of functional outcome after SCH treatment. Methods: We retrospectively analysed functional outcome in patients with SCH treated in our department between 2009 and 2020. We conducted a systematic search using PubMed, MEDLINE as well as EMBASE and performed pooled analysis including our cohort as well as other published studies including patients with SCH. Results: Our hospital cohort included 17 patients of which 9 were treated surgically. Mean age was 51.9 years, 58.8% of the patients were female. In 3/9 patients (33.3%) the neurological state remained stable after surgery. Five patients improved (55.6%) and one deteriorated after surgery (11.1%). Conservatively treated patients had a higher deterioration rate on follow-up with 3/8 patients deteriorating (37.5%). In our pooled analysis, 110/145 (75.9%) of patients improved, 31/145 (21.4%) remained stable and 4/145 patients deteriorated (2.8%). Among the available data of nine cohorts, mean recovery rate measured by the JOA score was 36.6% (SD 14.4). In our pooled multivariable model lower preoperative JOA score was associated with worse functional outcome (OR .86, 95% CI .74-.99, P = .04). Conclusion: Our data shows that patients who are treated surgically have a higher improvement rate and acceptable perioperative morbidity compared to conservatively treated patients. Lower preoperative JOA score decreases chances of improved functional outcome on follow-up. We therefore advocate early surgery for symptomatic patients. Wait and see appears outdated due to progressive impairment and decreased chances of recovery.

Keywords

Brown-Séquard-Syndrome, functional outcome, myelon herniation, myelopathy, spinal cord herniation, surgery.

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P619: Association Between MRI Findings and Back Pain After Osteoporotic Vertebral Fractures: A Multicenter Prospective Cohort Study

Sayed Abdullah Ahmadi ¹

¹ Wazir Akbar Khan Hospital, Orthopedic, Kabul, Afghanistan

Background Context: Osteoprotic vertebral fractures (OVFs) are common in elderly peo- ple. The association between back pain due to OVF with magnetic resonance imaging (MRI) signal change is unclear. In this study we hypothesized that MRI findings would be a predictive factor for back pain measured by visual analogue scale (VAS) at 6 months follow-up. Purpose: The aim was to study the MRI findings that predict back pain after OVF and the association between radiological findings and scores of back pain. Study Design: Multicenter prospective cohort study. Patient Sample: A total of 153 OVF patients. Outcome Measure: The outcome measures were VAS back pain and MRI signal change. Methods: This study was performed from 2012 to 2015. Consecutive patients with less than 2-week-old OVFs at 11 institutions were enrolled prospectively. MRI was performed at enrollment and at 1, 3, and 6 months follow-up. T1- and T2-weighted images (T1WI and T2W1) were obtained at each time point and their association with VAS scores of back pain at 6 months were investigated. Anterior compression ratio, posterior compression ratio, and angular motion of vertebral bodies were also measured on X-rays at each follow-up. This research had no financial support. There are no conflicts of interest. Result: The 6 months follow-up was completed by 153 patients. At enrollment, the average VAS score of back pain was 75 mm, and it had improved at the 6-month follow-up to an average score of 20 mm. There was a significant correlation between T1 diffuse low signal change and VAS scores at the 6-month follow-up (P < .01). T2 high signal changes (odds ratio; 4.01, P < .01) and old vertebral fractures (odds ratio; 2.47, P = .04) were independent risk factors for back pain. The correlation between angular motion of vertebrae on X-rays and the VAS score of back pain was significant at all time points. Conclusion: This study demonstrates the radiological factors associated with persistent back pain after an OVF and the association between the VAS score of back pain and radiological findings. In addition, T2 high signal changes in acute phase and old vertebral fractures were independent risk factors for residual back pain. © 2019 Elsevier Inc. All rights reserved.

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P620: Unique Patterns of Patient Factors Associated With Spine Trauma in the Elderly

Catherine Carlile ¹ , Andrew Rees ² , Jacob Schultz ² , and Byron Stephens ¹

¹ Vanderbilt University Medical Center, Nashville, USA

² Vanderbilt University School of Medicine, Nashville, USA

Introduction: As the population ages, the incidence of spine trauma in the elderly also continues to rise. Spine trauma includes a wide variety of injury patterns and range of severity in the elderly. With better understanding of the unique combination of patient comorbidities, mechanisms, and physical features associated with different spine injuries, better directed efforts can be made at prevention and risk management. The aim of this study is to better characterize the patient factors associated with different spine injury types as well as their severity in an elderly population. Methods: All elderly (65+) trauma patients with spine trauma who presented to a single, large, level I trauma center from 2010-2019, totaling 1725 patients. Retrospective chart review was completed to record comorbidities, presenting injury information, imaging findings, treatment, and long-term outcomes for all patients. A multivariable regression was conducted to assess for correlation or statistical difference between various patient characteristics and each injury category (eg, burst fractures). Additional multiple regression analysis was done to find factors associated with injury severity measures (eg, ISS). Outcome measures included injury type, divided into the following categories: burst, compression, flexion type, extension type, lateral mass, occipital condyle, odontoid, fracture-dislocation, and articular facet fractures/disruptions. Additional outcome measures included factors associated with injury severity measures, including Injury Severity Score, (ISS) and concomitant injuries (eg, multiple rib fracture). Results: A variety of factors, including sex, markers of osteoporosis and sarcopenia such as Hounsfield unit (HU) of the L3 vertebral body and psoas index, place of injury, and BMI were significantly associated (P < .05) with distinct types of injury. For example, Odontoid fractures (AO types A-C) were significantly associated increased age (P < .0001), dementia (P = .0025), low L3 HU (P = .0258), and low psoas total area (P = .0008). In contrast, other injury patterns, like flexion-distraction, had no significantly correlated factors. Several factors were significantly associated with increased ISS, including male sex (P = .0043), motor vehicle collision (MVC) mechanism (P < .0001), diabetes (P = .0232), and low L3 HU (P < .0001). Concomitant closed head injury, multiple rib fractures, pelvic fractures, and appendicular fractures also had significant associations with multiple patient characteristics (P < .05). Conclusion: The wide variety of comorbidities, physical attributes, and lifestyles seen in the elderly are associated with the equally broad spectrum of spine trauma see in this population. While some fracture patterns had strong associations with patient factors - sex, BMI, and bone density - other fracture patterns had no significant association with patient factors. Furthermore, injury severity is also associated with certain comorbidities and patient factors. Closer examination of these factors could provide insight into pathomechanism, epidemiology, and prevention. For example, focusing on treatments for osteoporosis and malnutrition in the elderly population may have protective benefits for certain injury patterns in spine trauma.

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P621: Does COVID-19 Affect Perioperative Morbidity and Mortality for Patients Required Emergency Instrumented Spinal Surgery? A Single-Centre Cohort Study

Fahid Rasul ¹ , Mathew Sewell ¹ , Kathak Vachhani ² , Fady Sedra ¹ , Syed Aftab ¹ , Suresh Pushpananthan ¹ , Jonathan Bull ¹ , Arun Ranganathan ¹ , and Alexander Montgomery ¹

¹ Royal London Hospital, Department of Spinal Surgery, London, United Kingdom

² University of Toronto, Toronto, Canada

Background: The COVID-19 pandemic sent shockwaves through health services worldwide. Resources were reallocated. Patients with COVID-19 still required instrumented spinal surgery for emergencies. Clinical outcomes for these patients are not known. The objective of this study was to evaluate the effects of COVID-19 on perioperative morbidity and mortality for patients undergoing emergency instrumented spinal surgery, and determine risk factors for increased morbidity/mortality. Methods: This retrospective cohort study included 11 COVID-19 negative, and 8 COVID-19 positive patients who underwent emergency instrumented spinal surgery in one United Kingdom hospital during the pandemic peak. Data collection was performed through case note review. Patients in both treatment groups were comparable for age, sex, body mass index (BMI), co-morbidities, surgical indication and preoperative neurological status. Predefined perioperative outcomes were recorded within a 30-day postoperative period. Univariable analysis was used to identify risk factors for increased morbidity. Results: There were no mortalities in either treatment group. Four COVID-19 positive patients (50%) developed a complication, compared with 6 (55%) in the COVID-19 negative group (P > .05). The commonest complication in both groups was respiratory infection. Three COVID-19 positive patients (37.5%) required intensive care unit (ICU) admission, compared with 4 (36%) in the COVID-19 negative group (P > .05). The average time between surgery and discharge was 19 and 10 days in COVID-19 positive and negative groups respectively (P = .02). In the COVID-19 positive group, smoking, abnormal BMI, preoperative oxygen requirement, presence of fever and oxygen saturations <95% correlated with increased risk of complications. Conclusion: Emergency instrumented spinal surgery in COVID-19 positive patients was associated with increased length of hospital stay. There was no difference in occurrence of complications or ICU admission. Risk factors for increased morbidity in patients with COVID-19 included smoking, abnormal BMI, preoperative oxygen requirement, fever and saturations <95%.

1792

P622: From Presentation to Treatment: An Expert Survey of Cases With Possible Spinal Posttraumatic Deformity

Erin De Gendt ¹ , Sander Muijs ¹ , Andrei Joaquim ² , Mohammad El-Sharkawi ³ , Gaurav Raj Dhakal ⁴ , Frank Kandziora ⁵ , Richard Bransford ⁶ , Emiliano Vialle ⁷ , Alexander Vaccaro ⁸ , Eugen Cezar Popescu ⁹ , Rishi Kanna ¹⁰ , David Polly ¹¹ , Klaus Schnake ¹² , Lorin Michael Benneker ¹³ , and Cumhur Oner ¹

¹ UMC Utrecht, Orthopedics, Utrecht, The Netherlands

² State University of Campinas, Department of Neurosurgery, Campinas, Brazil

³ Assiut University Medical School, Assiut, Egypt

⁴ Bir Hospital, National Academy of Medical Sciences, Kathmandu, Nepal

⁵ BG Unfallklinik Frankfurt am Main gGmbH, Frankfurt am Main, Germany

⁶ Harborview Medical Center/University of Washington Medical Center, Seattle, USA

⁷ Cajuru Hospital, Curitiba, Brazil

⁸ Rothman Institute, Philadelphia, USA

⁹ Prof. Dr. N. Oblu” Emergency Hospital, Bucharest, Romania

¹⁰ Ganga Hospital, Coimbatore, India

¹¹ University of Minnesota, Department of Orthopedic surgery, Minneapolis, USA

¹² Malteser Waldkrankenhaus St. Marien, Center for Spinal and Scoliosis Therapy, Erlangen, Germany

¹³ Sonnenhofspital, Spine Service, Orthopedic Department, Bern, Switzerland

Introduction: Spinal Posttraumatic Deformity (SPTD) is a complication of a spine trauma. Patients with SPTD suffer from disability and decreased function and quality of life. When a certain post traumatic spine deformity becomes clinically relevant is still unknown. In preparation of a Delphi study more information is needed on the diagnostic process of patients with possible SPTD. We want to investigate the diagnostic process of patients with complaints and/or deformity after a spine trauma to see what factors are thought to be more important in clinically relevant SPTD. Material and Methods: The survey of 7 cases was sent to 31 spine trauma and deformity experts. Every case had the same structure: a visit at the outpatient clinic (anamnesis, diagnostic assessment, evaluation of diagnostic assessment, diagnosis and treatment options). The factors in the survey were based on earlier research and face-to-face meetings. (Weighted) Means, ranges, percentages of the total of participants and descriptive statistics were calculated when possible, and otherwise narrative results were given. Results: In total 17 spine surgeons, all with >5 years experience completed the survey. The AO Spine Knowledge Forum Trauma was represented by 13, the AO Spine Knowledge Forum Deformity by 2 and 3 additional spine deformity surgeons completed the survey of the 7 cases. From the anamnesis, the functional impairment and the type of fracture that the patient had suffered were deemed most important. Least important for diagnosis from the anamnesis was the workstatus and the presence of medical comorbidities. In Cervical-spine (C) cases participants requested a cervical conventional radiograph (CR) (76-83%), a flexion/extension CR (61-71%), a CT-scan (76-89%) and a MR-scan (89-94%). In Thoraco-lumbar spine (ThL) cases a full spine CR (89-100%), a CT-scan (72-94%) and a MR-scan (65-94%) were requested most often. The participants rated the local deformity (given as Cobb and wedge angle) and the global alignment (given as thoracic kyphosis, thoracolumbar angle and the Lumbar lordosis) as more important in the assessments of the available radiological entities. There was consensus on 5 cases having SPTD (82-100%) and in 2 cases no consensus amongst the participants consisted (35-44%). When consensus existed on the diagnosis SPTD, there was also consensus on the case being compensated or decompensated and being symptomatic or asymptomatic. Unanimous agreement between the participant existed in the 2 C-cases to treat them surgically (mostly a 360-approach was mentioned). For the 2 ThL-cases with a consensus on having SPTD consensus was reached for surgical treatment. Consensus was reached on conservative treatment of 1 ThL-case without consensus on SPTD. No consensus for treatment existed for 2 other ThL-cases (1 with consensus on having SPTD). Conclusion: Among spine experts there is strong consensus on the use of certain imaging assessments in the cases. For C cases: cervical CR, a CT-scan and an MR-scan. For ThL cases: full spine CR, a CT-scan and an MR-scan. There was strong consensus on 5 out of 7 cases on diagnosis of SPTD. The results from this study will be used as a base in the adjusted Delphi study.

1798

P623: Safety, Effect and Feasibility of Percutaneous SI-Screw With and Without Augmentation - A 15-Years Retrospective Analysis on Over 640 Screws

Oliver Riesenbeck ¹ , Moritz Lodde ¹ , Jonas Keller ¹ , Maria Eveslage ² , Josef Stolberg-Stolberg ¹ , Michael Raschke ¹ , and René Hartensuer ¹

¹ University Hospital Muenster, Trauma-, Hand- & Reconstructive Surgery, Muenster, Germany

² University of Muenster, Institute of Biostatistics and Clinical Research, Muenster, Germany

Introduction: Percutaneous sacroiliac-screw (SI-screw) fixation is a well-established procedure for the minimal invasive treatment of posterior pelvic ring injuries. There is only limited clinical data available on risk, safety and immediate effects of SI-screw fixation. Materials and Methods: The present retrospective cohort study investigates percutaneous SI-screw fixation and augmentation over 15 years in a single, level I trauma center. Groups were compared concerning general epidemiological data, mobilization, complication rates, duration of stay, and safety of SI-screw insertion. Multivariable analyses were performed using logistic regression. Results: Between 2005 and March 2020, 448 patients with 642 inserted SI-screws were identified. Cement augmentation was performed in 118 patients. Iatrogenic neurological impairment was documented in 2.47 % (11/446 patient) and correlated with screw misplacement. Correct screw placement was found in 385 patients (91.2 %), whereas minor screw displacement (< 3.6 mm) was seen in 19 patients (4.5 %) and major screw displacement (>3.6 mm) was seen in 13 patients (3.1 %). In 5 cases revision surgery was performed (1.2 %). Cement associated complications were accounted in 22 % of the cases but out of these only 3 times (3/118) spinal extravasation and only two times (2/118) neuroforaminal extravasation was documented. No reduction of screw-related complications using 3D navigation was seen (P = .3076) in our collective. Cement augmentation showed a 25 % reduced postoperative stay in hospital and multivariable regression analysis revealed a reduced risk for major complications with augmentation versus none (OR .598). Conclusion: The present study shows that percutaneous SI-screw fixation is safe and effective. Neurological complications and screw malpositioning correlate closely. Cement augmentation of SI-screws can be considered a safe procedure with the benefits of a shortened hospital stay and less major complications.

1814

P624: Noval Corona Virus and 1500 Orthopaedics Interventions; Experience of a Teaching Hospital From Pakistan

Amer Aziz ¹

¹ Ghurki Trust Teaching Hospital, Orthopaedics and Spine Center, Lahore, Pakistan

Background: Corona virus, the COVID 19 is highly contagious and the health staff members are most exposed. General trend among surgeons and hospitals were to limit work for emergency surgeries only. Our hospital had practiced bit differently by doing elective procedures also. Objective: The aim of this study is to share our experience in doing emergency and elective orthopedic and spine surgical interventions during outbreak of Corona virus. Materials and Methods: The emergency and elective surgical procedures done at our department during lock down period from March 19^th to May 31^st 2020. Data of surgical interventions and steps taken for prevention of transmission of Corona virus among patients, paramedical and medical staff were analyzed using SPSS 21.0 version. Results: 75% of the interventions done were emergency while 25% were elective. Half of the patients came from the home town I-e Lahore, a city with 12 million population while others were from outside. Only 8 out of 140 staff members were affected from Corona virus and were recovered without any morbidity and mortality. Conclusion: Orthopedics and Spine emergency and elective surgeries can be carried out in Corona virus pandemic maintaining all the precautions from arrival of the patient up to discharge of the patient’s especially early disposal. All the health workers need proper health education and healthy environment.

1908

P625: Surgical Timing in Traumatic Spinal Cord Injury: Current Practice and Obstacles to Early Surgery in Latin America

Alisson R. Teles ¹ , Miguel Bertelli Ramos ² , Orlando Righesso ¹ , and Asdrubal Falavigna ¹

¹ Hospital Beneficente São Carlos, Neurosurgery and Spine Program, Farroupilha, Brazil

² Universidade de Caxias do Sul, Caxias do Sul, Brazil

Introduction: To evaluate current practice of Latin American spine surgeons regarding surgical timing in patients with traumatic spinal cord injury (tSCI) and to identify potential barriers for early surgery in this region. Material and Methods: A web-based questionnaire was sent to spine surgeons who were members of AOSpine Latin America. Questions involved demographic features, familiarity with management of tSCI, and timing of surgery in various tSCI scenarios. The participants were also asked if they would like to operate earlier on patients with tSCI, indicating potential obstacles to early surgery in these patients. Results: A total of 307 surgeons answered the questionnaire. Early surgery(<24 h) is performed by 66.8% for ASIA A, 76.9% for ASIA B, and 76.9% for ASIA C/D injuries. For traumatic cauda equina syndrome (tCES), 85.2% performed surgery within 24h. For traumatic central cord syndrome(tCCS) without osteoligamentous instability, only 31.5% performed surgery within 24h and 41.2% follow-up on these patients, indicating surgery if symptoms do not improve. Early surgery was performed always or in most cases by 50.4% and 41.8% of surgeons for incomplete and complete tSCI, respectively. Fellowship-trained spine surgeons are more likely to operate within 24 hours in patients with incomplete tSCI ASIA C/D and tCES patients (P < .001). Surgeons practicing in public hospitals are less likely to operate within 24 hours in all clinical scenarios (P < .01). No effect on surgical timing was observed in any of the clinical scenarios according to specialty (neurosurgery versus orthopedics), duration of practice, and volume of SCI per year. The majority (85.4%) would like to operate earlier on patients with tSCI than they actually do. The most frequently perceived barriers to early surgery were difficulty of access to surgical implants (70.9%) and delay in patient transport to reference hospital for surgery (57.8%). Only 11.6% of the participants believe there is not enough scientific evidence to support benefits of early surgery (<24 h) in tSCI. Neurosurgeons are more likely to report problems with spine implants compared to orthopedic surgeons (79.8% versus 64.3%, P = .006). On the other hand, orthopedic surgeons were more likely to report difficulty in accessing the OR, anesthesia or ICU than neurosurgeons (44.2% versus 28.1%, P = .007). Hospital facilities were also pointed out as an obstacle to perform early surgery more frequently by surgeons who did not undergo fellowship training in spine surgery (49.1% versus 34.1%, P = .038). Conclusion: This survey identified current practice regarding surgical timing in patients with spine trauma presenting with SCI, CES, and CCS. Latin American spine surgeons clearly have different approaches according to severity of injury. They tend to operate earlier on patients with CES and incomplete tSCI, compared to patients with complete tSCI and tCCS. Spine fellowship-training was associated with a higher likelihood of indicating early surgery for incomplete tSCI and tCES. Besides education, professionals working in public health systems were less likely to operate within 24 hours. We identified healthcare resources obstacles for early surgery for SCI in Latin America such as access to spine implants, OR, anesthesia team and ICU.

Acknowledgement

AOSpine Latin America.

Tumors

43

P626: A Novel Clinical Scoring System for Perioperative Morbidity in Metastatic Spinal Tumor Surgery: The Spine Oncology Morbidity Assessment Score

Rafael De la Garza ¹ , Joshua Benton ¹ , Yaroslav Gelfand ¹ , Murray Echt ¹ , Mousa Hamad ¹ , Merritt Kinon ¹ , Vijay Yanamadala ¹ , and Reza Yassari ¹

¹ Montefiore Medical Center, Neurosurgery, Bronx, USA

Introduction: Multiple scoring systems exist to predict survival for patients with spinal metastasis. The potential benefits and risks of surgery need to be evaluated for patients with disseminated cancer and limited life expectancy. Few scoring systems exist to predict perioperative morbidity after metastatic spinal tumor surgery (MSTS). The objective of this study was to evaluate a scoring system to predict morbidity for patients undergoing MSTS. Material and Methods: We reviewed records of patients who underwent MSTS at our institution between 2013 and 2019. All perioperative complications occurring within 30 days were recorded. A clinical scoring system consisting of five variables (age ≥70, hypoalbuminemia, poor preoperative functional status (Karnofsky ≤40), Frankel Grade A-C, and multilevel disease (≥2 continuous vertebral bodies) was evaluated as a predictive tool for morbidity; every parameter was assigned a value of 0 if absent or 1 if present (total possible score = 5). The effect of the scoring system on morbidity was evaluated using stepwise multiple logistic regression. Model accuracy was calculated by receiver operating characteristic analysis. Results: One-hundred and five patients were identified, with a male prevalence of 58.1% and average age at surgery of 61 years. The overall 30-day complication rate was 36.2%. The perioperative morbidity was 4.6%, 30.0%, 53.9%, and 64.7% for patients with scores of 0, 1, 2, and ≥3 points, respectively (P < .001). On multiple logistic regression analysis controlling for covariates not present in the model, the scoring system was significantly associated with 30-day morbidity (OR 3.11; 95% CI, 1.72-5.59; P < .001). The model’s accuracy was estimated at .75. Conclusion: Our proposed model was found to accurately predict perioperative morbidity after MSTS. The Spine Oncology Morbidity Assessment (SOMA) score may prove useful for risk stratification and possibly decision-making, though further validation is needed.

49

P627: Racial Disparities in Perioperative Morbidity Following Spine Oncological Surgery

Rafael De la Garza ¹ , Jong Hyun Choi ¹ , Ishan Naidu ¹ , Joshua Benton ¹ , Yaroslav Gelfand ¹ , Murray Echt ¹ , David J Altschul ¹ , Vijay Yanamadala ¹ , and Reza Yassari ¹

¹ Montefiore Medical Center, Neurosurgery, New York, USA

Introduction: Race is a known risk factor for disparities in outcome of major cancer surgery. However, there is limited data on the impact of race on outcomes after spine oncology surgery. The objective of this study was to assess the impact of race on complications following metastatic spinal tumor surgery. Material and Methods: Adults with cancer who underwent spine tumor surgery were identified in the American College of Surgeons National Surgical Quality Improvement Program datasets from 2012 to 2016. Clavien-Dindo Grade I-II (minor complications) and Clavien-Dindo Grade III-V (major complications including 30-day mortality) complications were compared between non-Hispanic Whites (NHW) and Black patients. A multivariable analysis was conducted to identify independent predictors of outcome. Results: Of 1,226 identified patients, 85.9% were NHW (n = 1053) and 14.1% were Black (n = 173). The overall rate of Grade I-II complications was 17.4%; 15.1% for NHW patients and 23.1% for Black patients (P = .008). On multivariable analysis, Black patients had significantly higher odds of having a complication compared to NHW patients (OR 1.87; 95% CI, 1.16 – 3.01; P = .010). On the other hand, the overall rate of Grade III-V complications was 13.3%; 12.5% for NHW patients and 16.2% for Black patients (P = .187). On multivariable analysis, Black race was not associated with higher odds of developing a major complication (OR 1.26; 95% CI, .71-2.23; P = .430). Median length of stay was 8 days (IQR 5-13) for NHW patients and 10 days (IQR 6-15) for Black patients (P = .011). Conclusion: In this study, Black patients who underwent metastatic spinal tumor surgery were at a significantly increased risk of perioperative morbidity compared to NHW patients independent of baseline and operative characteristics. Major complications did not differ between groups. Race should be further studied in the context of metastatic spine disease to improve our understanding of these cancer health disparities.

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P628: Metastatic Spinal Cord Compression as the First Manifestation of Malignancy - A Retrospective Study of Surgical Outcome From Single Institution Spine Tumor Registry

Ue-Cheung Ho ¹ and Fon-Yih Tsuang ¹

¹ National Taiwan University Hospital, Taipei City, Taiwan, Division of Neurosurgery, Department of Surgery, Taipei City, Taiwan

Introduction: The spine is a common site for metastasis, and the most common causes of metastases are breast, lung, and prostate cancer. Epidemiological studies have reported that metastatic spinal cord compression (MSCC) could be the initial presentation of malignancy in up to 20% of cases. The initial assessment of a patient with spine metastasis is important for guiding treatment and should incorporate performance status, systemic burden of disease, control of systemic disease, and systemic treatment options. This type of assessment does not apply for those with unknown primary cancer because tumor status cannot initially be evaluated. In addition, there is no time for comprehensive survey due to the neurological emergency that necessitates immediate surgical intervention. Given the limited studies addressing the issue about the effect of different surgical modalities for MSCC as the first malignancy manifestation, we conducted a retrospective case control study to evaluate the surgical outcome of MSCC as the first malignancy manifestation. Material and Methods: A total of 59 patients who were suspected of having metastatic spinal cord compression and underwent surgery from 2008 to 2017 were enrolled in the study. All patients were categorized into either ‘debulking group’ or ‘palliative group’. The primary outcome was progression-free survival (PFS) assessed by the investigator. PFS was defined as the time from surgery to the earlier detection of neurological deterioration. The secondary outcome was overall survival (OS). OS was defined as the time from surgery to death due to any cause. All the outcomes were analyzed with a data cutoff of December 31, 2017. Results: There was a significant difference between groups in progression-free survival (PFS) (P = .0036). However, there was no significant difference between groups in the overall survival (OS) (P = .8669). Age of onset, gender, duration of symptoms, and location of spinal metastasis, initial Frankel, initial Tomita scores, and initial Karnofsky performance scale showed no significant differences between groups. Conclusion: Debulking surgery was shown to provide better neurological recoveries and should be considered first in patients with metastatic spinal cord compression as the first malignancy manifestation.

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P629: Predictive Facts for Surgical Treatment in Spinal Tumors

Andriy Popov ¹ , and Dmytro Petrenko ²

¹ Sytenko Institute of Spine and Joint Pathology, Kharkiv, Ukraine

² Kharkiv University Clinic, Kharkiv, Ukraine

Introduction: Despite contemporary advances in the surgical management of spinal tumors selection of the appropriate treatment modalities varies between different institutions. Identification of key predictors affecting surgical intervention and final treatment outcomes might facilitate choice of the treatment options. Materials and Methods: We retrospectively reviewed 237 patients with spinal tumors treated in the single medical center. Clinical and radiological data and type of the surgical intervention were evaluated to define predictors that may affect clinical course and treatment decisions. Chi-square statistical analysis was performed using software STATISTICA 12 (TIBCO Software Inc., USA) and Microsoft Office Excel 2013 (Microsoft Corporation, USA). Results: Surgical intervention in the study group were vertebroplasy, vertebral augmentation with spinal fixation, separation surgery with spinal fixation and en bloc resection. Totally 9 potential predictors were selected for the further study such as: tummy localisation, pain, type of lesion, degree of epidural cord compression, local kyphosis, vertebral body collapse, ASIA scale, adjacent vertebra evolvement. The best predictors that have statistical significance were ASIA scale (81,6%), type of lesion (67,4%), epidural spinal cord compression (53,8%), type of surgey (25,1%). Decision tree for algorithmic approach to the selection of appropriate treatment has been developed. Conclusion: Among well known clinical components we defined that SIA scale, type of lesion, epidural spinal cord compression, type of surgey are the best predictors affecting surgical strategy and clinical outcomes.

113

P630: Surgical management of multiple myeloma with symptomatic involvement of the spine

Helena Milavec ^1,2 , Nivetha Ravikumar ² , Nicholas Syn ³ , Soekojo Cinnie Yentia ⁴ , Wee Joo Chng ⁴ , and Naresh Kumar ²

¹ Department of Orthopaedic Surgery, Inselspital, Bern University Hospital, Switzerland, Bern, Switzerland

² Department of Orthopaedic Surgery, National University Health System (NUHS), Singapore, Singapore

³ Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore

⁴ Department of Haematology-Oncology, National University Health System (NUHS) Singapore, Singapore, Singapore

Introduction: Multiple myeloma (MM) is the most frequent primary malignancy of the spine resulting in osteolytic lesions which may lead to spinal instability, pathologic fractures, and spinal cord compression (SCC) implying a high risk of neurological impairment and subsequent reduction in patients’ quality of life. We aimed to investigate the clinical presentation, surgical indications and outcomes, complications, survival and its influencing factors in surgically treated MM patients with symptomatic involvement of the spine (SIS). Material and Methods: Out of 350 MM patients treated at our institution over a period of twelve years (2006-2018), we identified 24 patients who were surgically treated for SIS. A retrospective analysis of prospectively-collected data on demographics, clinical presentation, comorbidities, surgical indications and outcomes was done and we investigated the factors predisposing to postoperative complications and survival. Results: The median follow-up duration was 85 months; median overall survival (OS) was 50 months. Clinical presentation at admission included pain (88%), sensory and/or motor deficit (67%) and bowel/bladder dysfunction (25%). Symptomatic pathological fractures were seen in one-third of our patients. Predominant surgical indications were rapid neurological deterioration ± SCC, followed by mechanical instability defined as fractures with a Spine Instability Neoplastic Score ≥ 7 combined with moderate to severe mechanical back pain. One-third of our patients received postoperative RT within 8 weeks after surgery as an adjuvant therapy. All our patients received single-agent or multi-agent anti-myeloma drug therapy. There were 21% patients with surgical-related complications (< 3 months). Surgical-site infections occurred in 17%, without any obvious factors predisposing to infective complications. Neurological deterioration during hospital stay, especially in the presence of motor deficit and/or bowel/bladder dysfunction, significantly reduced OS. Conclusion: Rapid neurological deterioration had predominantly led to surgery. Deterioration of motor deficits and/or bowel/bladder dysfunction during hospital stay reduced OS. We have achieved good short and long-term pain reduction. Surgery is a valuable option for MM patients with SIS who present with rapid neurological deterioration ± SCC and/or mechanical instability.

114

P631: Surgical Management of Spinal Lesions in Multiple Myeloma: Factors Influencing Length of Hospital Stay and Readmissions

Helena Milavec ^1,2 , Nivetha Ravikumar ² , Nicholas Syn ³ , Soekojo Cinnie Yentia ⁴ , Wee Joo Chng ⁴ , and Naresh Kumar ²

¹ Department of Orthopaedic Surgery, Inselspital, Bern University Hospital, Switzerland, Bern, Switzerland

² Department of Orthopaedic Surgery, National University Health System (NUHS), Singapore, Singapore

³ Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore

⁴ Department of Haematology-Oncology, National University Health System (NUHS) Singapore, Singapore, Singapore

Introduction: Approximately 70% of multiple myeloma (MM) patients present with spinal involvement. There is dearth of literature on outcome measures such as hospital length of stay (LOS) and readmissions and the influence of patient- or surgical-related factors in patients undergoing myeloma-related spinal surgery. We aimed to investigate variables affecting LOS and readmissions in patients operated for symptomatic spinal lesions in MM. Material and Methods: Retrospective study of prospectively-collected data on 24 consecutive MM patients operated for symptomatic spinal lesions at our institution from 2006 to 018. Acute LOS was analyzed using both non-parametric and parametric methodologies to enhance the robustness. 30-day, 3-month, and 1-year readmissions were investigated by logistic regression, focusing on demographics, comorbidities, surgery details, and complications. Results: Mean LOS was 37.2 ± 34.6 days. Factors significantly associated with prolonged LOS in absolute and relative terms were the presence of motor deficit and/or bowel/bladder dysfunction (+79 days) and poor pre-operative ambulatory status (+28 days). Readmission rates for 30 days, 31 days-3 months and 3-12 months were 17%, 17% and 33% respectively and most common caused by systemic infections. Predisposing factor for readmission was pre-operative ambulatory status (P = .022). Conclusion: Relevant factors leading to a significant increase in LOS were the presence of motor deficit and/or bowel/bladder dysfunction, a poor pre-operative ambulatory status. Overall, there were 12 patients with 26 unplanned readmissions within 1 year post-operatively, with non-surgical systemic infections being the most common cause. Pre-operative ambulatory status was the only predisposing factor for readmission.

119

P632: Pure Spinal Intramedullary Breast Cancer Metastasis: Presentation of 4 Cases

Gulden Demirci Otluoglu ¹ , Onder Ertem ² , Zafer Orkun Toktas ¹ , and Deniz Konya ¹

¹ Bahçeşehir University School of Medicine, Neurosurgery, Istanbul, Turkey

² Bahçeşehir University School of Medicine, Istanbul, Turkey

Introduction: Pure spinal intramedullary metastasis in neurosurgical practice is a rarely seen entity. In this paper we aimed to present 4 consecutive patients with pure spinal intramedullary metastasis of breast cancer patients’ data operated in a single center. Materials and Method: All patients who were operated in Bahçeşehir University School of Medicine Department of Neurosurgery between June 2012 and February 2020 were searched for this study. Four patients who were diagnosed and operated for pure spinal intramedullary metastasis of breast cancer have been recruited. Results: Case 1: 46-year-old female patient with an intramedullary metastasis located at C5-6 level. She was operated and under follow-up at post-operative 64^th month. Case 2: 33-year-old female patient with an intramedullary metastasis located at T11-12 level. She was operated and died due to leptomeningeal metastasis at post-operative 4^th month. Case 3: 56-year-old female patient with an intramedullary metastasis located at T12-L1 level. She was operated and died due to multiple hemorrhagic intracranial metastasis at post-operative 1^st month. Case 4: 55-year-old female patient with an intramedullary metastasis located at L1 level. She was operated and under follow-up at post-operative 1^st month. Conclusion: Pure spinal intramedullary metastasis of breast cancer is a rarely seen entity. The survival of these patients is less than expected but for reducing the morbidity of the neurological decline these patients need surgical interventions.

176

P633: Primary Spinal Epidural Non-Hodgkin's Lymphoma: A Rare Cause of Acute Spinal Cord Compression

Shaffaf Kareem ¹

¹ Vardhman Mahavir Medical College & Safdarjung Hospital, Spine care Unit, New Delhi, India

Introduction: Non-Hodgkin’s lymphoma (NHL) of the spine constitutes a diagnostic challenge due to its resemblance to other spinal tumor syndrome cases and also due to the difficulty in demonstrating a tissue diagnosis. Biopsy can be inconclusive, oftentimes requiring surgical excision biopsy. Hence having poor prognosis. Material and Methods: A 25-year-old male presented with chief complaints of pain over mid back region for 7-months which was insidious in onset, dull aching in nature, non-radiating and without diurnal variation. He also developed weakness in both lower limbs since 5months, which was insidious in onset, starting in right lower limb and progressing to the left as well within a span of 15days along with loss of bladder and bowel control. He also gave history of occasional fever and loss of appetite since last 5months. On examination, he had deep tenderness over D4-5 region without local rise of temperature & without any deformity. No significant lymphadenopathy or organomegaly was present. Both upper limbs had normal sensory-motor examination. There was sensory loss of all modalities below D5 level. Both lower limbs had 0/5 power with flaccid tone and absent deep reflexes. Bulbocavernosus reflex and perianal sensation were absent. Radiographs showed collapse of D6 vertebrae. Magnetic Resonance Imaging (MRI), showed large epidural abscess from D2 to D8 level with collapse of D6 vertebrae. Total leucocyte count was 11,300/mm³ of blood, c-reactive protein positive & erythrocyte sedimentation rate 50mm/hr. CT-guide biopsy of the D6 vertebra was inconclusive. Excisional biopsy was then done by laminoplasty at D5-D6 level and skip laminotomy at other levels from D2 to D8. Large epidural membrane and 3ml of cheesy material was obtained from the epidural space and were sent for histopathological examination. Result: Histopathology report came as small round blue cell tumor (NHL). He was then given chemotherapy from medical oncology department with a regime of Hyper-CVAD cyclophosphamide, vincristine, doxorubicin, and dexamethasone. He is now being further planned for radiation therapy of the thoracic spine with continued chemotherapy. Discussion: Spinal lymphoma is a relatively uncommon spinal tumor and accounts for 1-2% of lymphomas’ extra-nodal occurrence and 10% of epidural tumors. NHL accounts for 85% of spinal lymphoma cases, with the majority being diffuse large B cell lymphomas. In a proposed diagnostic algorithm, if there is spinal instability or severe cord compression, primary surgical intervention and pathological examination is recommended; and if the spine is deemed stable and in the presence of a mild to moderate compression, needle biopsy can be attempted followed by a trial of chemo-radiation. Treatment strategies lack strong evidence and involve chemotherapy, steroids, radiation therapy, stem cell transplant and surgery. Primary spinal lymphoma seems to have an unfavorable prognosis with survival estimates varying from 36% to 100% in 2years. Hence, spine surgeons should keep this relatively rare entity as a differential diagnosis of patients presenting as spinal tumor syndrome.

201

P634: "Spine in Spine" a Novel Technique for Reconstruction of the Anterior Column Following En-Bloc Tumour Resection

Valerio Pipola ¹ , Nandan Marathe ^1,2 , and Alessandro Gasbarrini ¹

¹ Instituto Orthopedico Rizzoli, Bologna, Italy

² Toronto Western Hospital, Toronto, Canada

Introduction: Numerous methods for anterior column reconstruction have been described previously, each having its own pros and cons. However, strong evidence proving superiority of one method over other is lacking. Here we present a case in which anterior column reconstruction was done using vertebral bodies grafted from a cadaver. Materials and methods: Case: A 77 yr male patient presented in 2014 with a history of back pain. Imaging was done and treatment in the form of radiotherapy for aggressive hemangioma of the D12 vertebra was started. Biopsy was not performed prior to starting the radiotherapy. Patient presented in 2018 with complaints of back pain and lower limb radiculopathy. Imaging showed a lesion in the D11-12 vertebral body. Laminectomy, incisional biopsy and intralesional debulking was performed. Patient had relief of symptoms following procedure. Histology showed presence of a Chordoma. Patient was planned for Proton beam radiotherapy and it was decided that Enbloc resection of vertebra is needed prior to commencing the proton beam therapy. Results: Patient was operated by the double approach for vertebrectomy. Anterior reconstruction was planned using vertebral bodies grafted from a cadaver. These bodies were grafted 2 weeks prior to the planned procedure and stored at 0 degrees in the institutional bone bank. Intervertebral discs were removed and the 4 bodies were converted to one bone block. A high speed burr was used to make a tunnel through the vertebral bodies and these were connected with a long rib graft that was removed during the anterior approach for vertebrectomy. Posterior elements of all bodies were removed. These were then drilled and tapped sequentially in order to allow passage of pedicle screws. Posterior fixation was done 3 levels above and below with a pedicle screw and rod construct. The vertebral bone block was now used for anterior column reconstruction. It was fixed and included in the construct by passing two pedicle screws. Conclusion: En bloc resection is the surgical procedure which involves removal of entire tumor as a single piece encased together along with a layer of healthy tissue. Traditionally, autologous tricortical iliac bone graft was the “gold standard” for reconstruction of corpectomy. In extensive surgery, a large amount of bone autograft produced morbidity at donor site. We provide an alternative option which obviates disadvantages of other modalities. Cadaveric vertebral bone is available in large quantity without donor morbidity at a lower cost. Also, it mimics native vertebra in terms of shape as well as mechanical properties. It can be included in construct by passing pedicle screws through it. In our case, we removed the intervertebral discs in between two bodies to allow solid bony fusion. However, preservation of native disc may mimic load bearing properties of vertebra and further study is needed in this regard. As per our knowledge, this is the first instance of “Spine in Spine” construct where anterior column reconstruction has been attempted using cadaveric vertebral bone.

327

P635: Surrogate Markers of Frailty in Metastatic Spine Disease: A Systematic Review

Mark Maclean ¹ , Charles Touchette ² , Tristan Brunette-Clement ³ , Fahad Abduljabba ⁴ , Michael Weber ⁵ , and Daryl Fourney ⁶

¹ Dalhousie University, Division of Neurosurgery, Halifax, Canada

² University of Sherbrooke, Division of Neurosurgery, Sherbrooke, Canada

³ Universite de Montreal, Montreal, Canada

⁴ King Abdulaziz University Hospital, Saudi Arabia, Canada

⁵ McGill University, Montreal, Canada

⁶ University of Saskatchewan, Saskatoon, Canada

Introduction: Scoring systems accounting for burden of malignancy and neurologic status have been developed to estimate survival for patients with spinal metastatic disease (SMD). Despite the inherent importance of physical reserve and ability to tolerate surgery, pre-operative patient-specific surrogate markers of frailty that may improve accuracy of outcome prognostication for patients with SMD are not well described. Materials and Methods: A systematic review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. MEDLINE, Scopus, EMBASE, Cochrane Registry of Controlled Trials, CINAHL, and Web of Science were searched. Quality of the evidence was scored using the Oxford CEBM Scoring Tool. Results: Forty studies accounted for 8,364 patients. Thirty-eight were retrospective. Surgical indications included neurological dysfunction, intractable pain, and spinal instability. Histology varied greatly, the most frequent types being lung, kidney, breast, and prostate. Age, gender, neurologic condition, and performance status were the most frequently analyzed variables. Multivariate analyses seldom revealed statistical significance. Few studies examined health-related quality of life, biochemical abnormalities, patient comorbidities, and lifestyle variables. Overall, evidence quality was low. Conclusions: Frailty was not clearly defined across studies. Our findings indicate that surrogate markers of frailty do not consistently predict post-operative survival in the setting of metastatic spine disease. Objective measures of frailty may improve risk stratification and outcome prognostication.

350

P636: Is Excission Is Suffice for Sacrococcygeal Teratoma?

Prof. Dr. Md. Anowarul Islam ¹

¹ Bangabandhu Sheikh Mujib Medical University, Orthopaedics, Dhaka, Bangladesh

Introduction: Chordomas are slow-growing malignant neoplasms that arise from embryonic notochordal remnants, represent approximately 1-4% of all primary bone tumors. Sacral chordomas arises in the sacrum and represent greater than 50% of all tumors of the sacrum. Due to their relatively slow growth rate, sacral chordomas often remain clinically silent until the lesions reach a large size. When symptomatic, these tumors commonly present with non-specific and progressive deep pain and/or radiculopathy and require surgical excision. Material and Methods: 20 patients of sacral chordoma were treated by surgical excision in Bangabandhu Sheikh Mujib Medical University and othe private hospitals in Dhaka city fom January 2008 to December 2019. Out of 20 patients, 12 had done subtotal sacrectomy and the remaining 8 had done partial sacrectomy. Their follow-up periods were at least four years. Operative time ranged between two to four hours. Results: All patients recovered well from operation and two to five units of blood transfusion were needed for each. After operation, majority of the patients developed some bowel and bladder dysfunction and five patients developed wound infection. During the follow-up, two patients had tumor recurrence and one patient expired two years after operation. The remaining 17 patients were tumor-free at the 4 years follow-up. Conclusion: Wide surgical resection via the posterior midline approach could be a good management plan for the sacral chordoma. However, complete removal with surgical margin varies according to the location of the tumor.

391

P637: Surgical Intervention and Treatment Protocol for Enneking Stage III Vertebral Hemangiomas

Abdullah Bin Shabib ¹ , Faisal Konbaz ¹ , Monerah Annaim ¹ , Abdulrahman Alabdulkareem ¹ , Anouar Bourghli ² , Fahad Alhelal ¹ , and Sami Aleissa ¹

¹ King Abdulaziz Medical City., Department of Surgery, Division of Orthopedics., Riyadh, Saudi Arabia

² Kingdom Hospital, Orthopedics, Riyadh, Saudi Arabia

Background: Vertebral hemangiomas are rare benign, slow growing tumors. Treatment of Enneking stage 3 (ES3) vertebral hemangiomas is still controversial and comprehensive treatment protocol is lacking. We hereby describe a series of 11 cases of ES3 vertebral hemangioma, and provide an updated treatment algorithm. Methods: A retrospective review of consecutive series of ES3 vertebral hemangiomas treated at two centers from 2010 to 2020. Results: A Total of 11 patients diagnosed with ES3 vertebral hemangiomas were identified. Mean follow up was 32.3 ±24.8 months. All patients were symptomatic; the most common presentations were neurological deficit and/or myelopathy (n = 7). Ten patients underwent intralesional spondylectomy. Six patients had preoperative embolization, with mean blood loss of 880 ±334.46 ml. One patient refused surgery and underwent vertebroplasty and multiple sclerotherapy sessions. All patients had full neurological recovery during follow up and no recurrence was reported. Conclusion: Intralesional spondylectomy showed good results in treating ES3 vertebral hemangiomas. However, larger studies comparing treatment methods are needed to reach a gold standard approach.

412

P638: The Use of Carbon Fibre/Polyetheretherketone in Pedicle Screw Fixation for Spinal Neoplasms - Potential Advantages in Postoperative Outcomes and Radiotherapy Planning

Daniel Ho ^1,2 , Ralph Mobbs ^1,2 , Colin Chen ³ , and Callum Betteridge ^1,2

¹ University of New South Wales, Faculty of Medicine, Sydney, Australia

² NeuroSpine Surgery Research Group, Sydney, Australia

³ Prince of Wales Hospital, Department of Radiation Oncology, Sydney, Australia

Introduction: A combination of surgery and postoperative external beam radiotherapy is commonly used in the management of patients with spinal tumors. Posterior stabilization with pedicle fixation is used as an adjunct to tumour decompression when significant soft tissue and bony resection is required. Titanium pedicle fixation constructs is problematic in postoperative radiotherapy because it impedes radiotherapy planning and dose delivery. Metal artefact on imaging prevents clear visualization and tumour delineation when planning a target volume for photon radiotherapy. Titanium’s high density may be incompatible with dose calculation algorithms, necessitating manual tissue density reassignment, and can result in an inaccurate dose prediction. Carbon fiber-reinforced polyetheretherketone (CF/PEEK) is a novel material that can address the limitations of titanium, as it is biomechanically non-inferior but radiolucent. The aim of this study is to investigate the efficacy and safety of CF/PEEK pedicle fixation compared to titanium in various aspects of surgery and radiotherapy. Material and Methods: CF/PEEK pedicle fixation was compared to titanium pedicle fixation at three levels: dose calculation accuracy with individual screws, image quality using water phantom models, and postoperative safety with a retrospective cohort of tumour patients with titanium or CF/PEEK pedicle fixation. Transverse dose profiles through the screw and tulip were obtained from individual screws irradiated with a fixed dose delivered orthogonally to the screw at 6 MV and 10 MV. This was compared to dose profiles generated by the treatment planning software. Water phantom models were created using lumbar spine models, with a CF/PEEK or titanium construct. Regions of interest (ROIs) were defined around the vertebra and screws. The standard deviation of CT-HU values were measured to calculate the artefact index. The mean artefact index at these ROIs were compared between the two models. A retrospective review of medical records was performed on 17 tumour patients who had been treated with CF/PEEK (10) or titanium pedicle screw fixation (7). Data compared included: postoperative course, incidence of hardware-related and postoperative complications, incidence of disease progression and mortality. Results: Titanium screws, especially at the tulip, have poorer agreement between measured dose and predicted dose (±5% vs ±2% ). The dose difference is worse at greater depths, and at 10 MV compared to 6 MV. Artefact index in the CF/PEEK models were lower than titanium models in all ROIs, however, statistically significant differences were not found at the ROIs corresponding to the spinous process and right transverse process. There was no difference in hospitalisation, time to postoperative radiotherapy and length of follow up. The incidence of postoperative complications was higher in the CF/PEEK cohort, however this result is likely anomalous due to small sample size. There was no association between material type and the incidence of hardware-related complications, disease progression or death. Conclusion: CF/PEEK pedicle fixation is non-inferior to titanium pedicle fixation in terms of postoperative safety. It has minimal benefit in dose calculation accuracy, but significantly improves image quality by reducing artefact. We recommend the use of CF/PEEK pedicle fixation in patients undergoing postoperative radiotherapy to improve radiotherapy planning.

594

P639: Intercultural Adaption of the SOSGOQ2.0 Questionnaire Into a German Version and It's Multicentric Validation

Wadim Kisel ¹ , Datzmann Thomas ² , Kramer Judith ¹ , Dreimann Marc ³ , Mueller-Broich Jacques D. ⁴ , Cordula Netzer ⁵ , Schaser Klaus-Dieter ⁶ , and Disch Alexander C. ⁷

¹ University Hospital Carl Gustav Carus, Technische Universität Dresden, University Comprehensive Spine Center (UCSC) University Center for Orthopedics, Traumatology and Plastic Surgery (OUPC), Dresden, Germany

² University Hospital Carl Gustav Carus, Technische Universität Dresden, Center for Evidence-Based Healthcare, National Center for Tumor Diseases Dresden, Dresden, Germany

³ University Hospital Hamburg-Eppendorf, Center for Surgical Medicine, Clinic and Polyclinic for Traumatology and Orthopedics, Hamburg, Germany

⁴ Orthopedic University Hospital Friedrichsheim, Frankfurt (Main), Germany

⁵ University Hospital Basel, Spine Surgery, Basel, Switzerland

⁶ University Hospital Carl Gustav Carus, Technische Universität Dresden, University Comprehensive Spine Center (UCSC), University Center for Orthopedics, Traumatology and Plastic Surgery (OUPC), Dresden, Germany

⁷ University Hospital Carl Gustav Carus, Technische Universität Dresden University Comprehensive Spine Center (UCSC), University Center for Orthopedics, Traumatology and Plastic Surgery (OUPC), Dresden, Germany

Introduction: Patients with malign tumors continuously benefit from a better and longer disease control (Quaresma et al., 2015) but have in turn a higher risk for spinal metastases. In a palliative situation, health related quality of life (HRQOL) is coming more into focus. The Spine Oncology Study Group Outcomes Questionnaire (SOSGOQ) was proven to be a valid and reliable instrument measuring HRQOL in native English speaking patients suffering from spinal malignancies (Street et al., 2010). A German version was not available, yet. The goal of this study was to interculturally adapt and apply this tool in German speaking patients. Material and Methods: Following consent of the Knowledge Forum (KF) Tumor of the AOSpine an intercultural adaptation of the SOSGOQ2.0 was performed according to the guidelines published by Beaton (Beaton et al., 2000). In a multistep translation and re-translation process the SOSGOQ2.0_GER was developed. Reliability is measured at two different days, at the same day time, within a week, without a therapeutical intervention in between (t1, t2). A further assessment followed 4 weeks after t1 (t3). Furthermore the tool was tested in comparison to the generic EORTC QLQ-C30 questionnaire (Sprangers et al., 1993) for overall and domain-specific (physical-, social-, mental functioning, pain) external construct validity. (Cronbachs alpha, Inter-Item correlation, ROC curve analysis). Results: In this multicenter study 51 male and 53 female patients were recruited. Average age was 65.5 (±11.1) years, average performance status ECOG graded 1.98 (±.99). Most frequent tumors were metastases of the prostate (n = 20), breast cancer (n = 14) and spinal lesions of multiple myeloma (n = 13) followed by other malignancies (n = 57). Treatment was intended in 77 patients pallatively, in 13 curatively and in 15 unclearly. Test-reliability for the SOSGOQ2.0_GER questionnaire was approved by the TOST-method (two one-sided t-tests) (Lakens, 2017) (first 20 patients reaching t2, P = .05, α = .1). 89 patients were considered in the preliminary statistical analysis. An excellent external construct validity in comparison to the EORTC QLQ-C30 questionnaire was approved for the overall construct and the single domains (physical-, social-, mental functioning, pain). The Bland-Altman method (P = .05, α-error 10%, power 80%) was used to compare both measurement instruments regarding their agreement in measuring HRQOL. All comparisons were within the predetermined limits of 10% error (in fact mostly <5%). Conclusion: The SOSGOQ2.0_GER-questionnaire is a reliable and valid tool to measure HRQOL. This tool can be highly recommended for future studies and after publication versatilely applied in German speaking patients with malign tumors of the spine.

596

P640: Brown Tumor of the Spine in Patients With Secondary Hyperparathyroidism

Kais Maamri ¹ , Ines Cherif ¹ , Mohamed Amine Hadj Taieb ¹ , Amine Trifa ¹ , Nessrine Nessib ¹ , Maher Hadhri ¹ , Mohamed Badri ² , and Mehdi Darmoul ¹

¹ Fattouma Bourguiba University Hospital, Neurosurgery, Monastir, Tunisia

² Trauma and Major burns center Ben Arous, Neurosurgery, Ben Arous, Tunisia

Introduction: Brown tumors or osteoclastomas or ‘Von Recklinghausen’s disease’ of the bone are erosive but benign lesions of the bone, caused by increased osteoclastic activity. These lesions occur in the severe forms of primary or secondary hyperparathyroidism. The most usual localization of brown tumors is in mandible, ribs and large bones. Involvement of the spine with this tumor causing neural compression is extremely rare. A review of the literature has shown that 56 cases of Brown Tumor have been reported to date. These tumors were described in 4.5% of the patients with primary hyperparathyroidism and in 1.5-1.7% of those with secondary hyperparathyroidism. The aim of this study is to describe our experience in diagnosis and management of patients with spine brown tumor caused by hyperparathyroidism and also to review the pertinent literature. Methods: We describe 3 cases of spine brown tumor in patients with secondary hyperparathyroidism. Clinical, radiological, histopathologic, and surgical data of these 3 cases were collected. Results: There were 2 females and a male with age range from 36 to 42 years. The lesions were located in cervical (1 case), thoracic (1 case), and thoracolumbar junction (1 case) spine regions. Clinical presentations included neck and back pain, radicular pain, paraparesis, and sphincter dysfunction. Laminectomy surgery was done in thoracolumbar cases and discectomy with partial corporectomy by anterior approach surgery in cervical case. Spine instrumentation was done in 2 cases. Parathyroidectomy was performed. The follow-up ranged from 18 to 36 months. We found neurological improvement in all cases. Conclusion: Brown tumors are part of a systemic disease and should be considered in the differential diagnosis of bone lesions in patients with hyperparathyroidism. These tumors should be kept in mind in expansive-lytic lesions of the spine. An emergent decompressive surgery may be necessary to preserve neurological function and to stabilize the spine in patients with pathological fracture.

Keywords

brown tumor, hyperparathyroidism, spine.

602

P641: Exploration and Clinical Application of New Indicators for Prognosis Evaluation of Solitary Plasmacytoma of Bone

Hanqiang Ouyang ¹ , Shaomin Yang ¹ , Yan Liu ¹ , Liang Jiang ¹ , Feng Wei ¹ , and Zhongjun Liu ¹

¹ Peking University Third Hospital, Beijing, China

Introduction: Solitary plasmacytoma of bone (SPB) is relatively indolent and maybe the early stage of multiple myeloma (MM). SPB might progress into MM through the accumulation of genetic changes, but little has been done on its molecular characteristics. Knowing the molecular mechanism of SPB will provide an objective evaluation of its progression risk and individualize treatment for patients with high-risk factors. Material and Methods: Our team has accumulated a preliminary database of 40 SPBs with long-term follow-up. To explore its basic genetics characteristics, fluorescence in situ hybridization (FISH) tests were successfully applied in several cases with the archived tumors kept in formalin-fixed and paraffin-embedded (FFPE) tumor blocks. Results: Using the criteria of two or more trisomies from a 3-chromosome combination (chromosome 9, 11, 15), hyperdiploid could be detected in 42.9% (6 in 14) SPB cases. On the other hand, IgH rearrangement could be detected in 29.4% (5/17) cases by IgH breaking apart probes. As for the genetic changes considered as high-risk indicators in MM prognosis, P53 (17p13) deletion and RB1 (13q14) deletion present in 47.1% (8/17) or 64.7% (11/17) of SPB cases, respectively. Besides, amplification of 1q21 has been detected in 22.2% (4/18) cases. Conclusion: The percentage of hyperdiploid and high-risk factors in SPB was remarkably similar to their percentages in MM reported in the literature, suggesting that these basic genetic features may originate in the SPB early stage before MM evolution, other molecular events might occur during the pathogenesis from SPB to MM, and remain to be studied using more advanced technologies including high throughput next-generation sequencing.

608

P642: Asymptomatic Construct Failure After Metastatic Spine Tumour Surgery: A New Entity or a Continuum With Symptomatic Failure?

Naresh Kumar ¹ , Ravish Patel ¹ , Barry Wei Loong Tan ¹ , Jiong Hao Tan ¹ , Naveen Pandita ¹ , and Keith Gerard Lopez ¹

¹ National University Health System, Singapore, Singapore

Introduction: The reported incidence of implant and/or construct failure(CF) after metastatic spine tumour surgery(MSTS) is low (1.9%-16%). These incidence rates are based on clinical presentations or revisions required for symptomatic failures(SF). Asymptomatic construct failure(AsCF) after MSTS has not been clearly described in the literature. The aim of this study was to evaluate the incidence, onset, underlying mechanism, clinical course, and factors leading to AsCF after MSTS. Materials and Methods: We conducted a retrospective analysis of 288-patients undergoing MSTS between 2005–2015. Exclusion criteria were: 1) patients with age <18-years, 2) patients who had prior spine surgery for non-metastatic cause, 3) patients with deep surgical site infections, or 4) patients with survival <30-days after MSTS. Institutional review board approval was obtained prior to initiation of study. Demographic data, perioperative and postoperative radiological and clinical features were collected from records of eligible patients. Radiological criteria for CF were defined. AsCF was defined as radiologically detectable changes in construct appearance/integrity (implant and/or bone), without pain/neurological deficit/deterioration in mobility from the peak post-operative mobility status. Early and late failures were defined as presentation before and after 3-months, respectively. Patients with AsCF were analysed for risk factors and survival duration. Competing risk regression analyses were done where AsCF was the event of interest, and SF and death were the competing events. Results: A total of 246-patients were included in the final analysis. Mean age at the time of surgery was 59 years (21-87 years); 51.6% were males. The most common primary tumour type was lung (27.6%), followed by breast (16.7%), and haematological (12.9%). Out of the 246-patients, CF was noted in 55 (23.4%) with 14 (25.5%) SF and 41 (74.5%) AsCF. Early AsCF accounted for 80% (n = 33). Average time to onset of AsCF after MSTS was 2-months (1–9 months). The most common radiologically detectable AsCF mechanism was angular deformity (increase in kyphosis) (n = 29, 71%) followed by screw loosening and screw ploughing (n = 15 each, 37%). Increasing age (P < .02) and primary breast tumours (13/41, 31.7%) (P < .01) were associated with significantly higher AsCF rates. There was a trend towards AsCF in patients with spinal instability neoplastic score (SINS) ≥7, instrumentation across junctional regions and construct length of 6–9 levels, although not significant. None of the AsCF patients underwent revision surgery during the study period. The median survival of AsCF patients was 20-months and 41-months in early and late failure groups, respectively. Kaplan-Meier survival curves showed that the survival time was significantly higher in patients with AsCF than patients with no failure or SF (P < .05). Conclusion: The concept of ‘AsCF’ after MSTS is a new entity. Majority of early AsCF do not require any intervention. Late failure is seen in patients who survive and maintain ambulation for longer periods. Increasing age and better prognostic tumours have a higher possibility of developing AsCF. AsCF is not necessarily an indication for aggressive or urgent intervention. We recommend more frequent follow-ups in these patients with further investigations and careful considerations for intervention, only in case of progressive symptoms.

628

P643: Primary Epidermoid Cyst of the Cauda Equina

Khalil Ayadi ¹ , Fatma Kolsi ¹ , Mansour Khrifech ¹ , Anis Hachicha ¹ , Brahim Kammoun ¹ , and Boudawara Mohamed Zaher ¹

¹ Habib Bourguiba University hospital, Neurosurgery, Sfax, Tunisia

Introduction: Intraspinal epidermoid cyst is very rare. It represents .5 to 1% of all spinal tumors. The cauda equina is an uncommon location in such cases. Material and Methods: We report the case of a patient who was treated in the department of neurosurgery in the Habib Bourguiba hospital for a primary epidermoid cyst located in the cauda equina. Results: We report the case of a 44-year-old female. The patient has been suffering from chronic lumbar pain for two years. During the last two months, she reported a weakness of both lower limbs with a retention type sphincter malfunction. Neurological examination showed paraparesis with abolished deep tendon reflexes. Lumbar spine MRI showed a posterior intradural and extramedullary oval tumoral formation extending from L1 to L5. Surgery was performed and complete removal was not possible due tight adherences to the cauda equinanerve roots. Histological examination was in favor of an epidermoid cyst. The patient had a good recovery. She was symptom-free few weeks after surgery. Conclusion: Epidermoid cyst of the cauda equina is a rare finding. Despite its location and surgery difficulties, the post-operative results are promoting.

629

P644: Primary Neuroectodermal Tumor of the Spine

Khalil Ayadi ¹ , Fatma Kolsi ¹ , Anis Hachicha ¹ , Mansour Khrifech ¹ , Firas Jarraya ¹ , and Boudawara Mohamed Zaher ¹

¹ Habib Bourguiba University hospital, Neurosurgery, Sfax, Tunisia

Introduction: Primary neuroectodermal tumor is a malignant neural crest tumor. It usually develops in the brain in children and young adults. Secondary localization in the spine is possible through the cerebrospinal fluid. However, a primary localization is rare. Material and Methods: We report the case of a young patient who was treated for a primary neuroectodermal tumor located in the lumbar spine, in the department of neurosurgery in the Habib Bourguiba hospital in Sfax, Tunisia Results: The patient is a 33-year-old man. He had no previous medical history. He was complaining of lower back pain for 6 months. He was admitted to our department for sudden exacerbation of the pain with walking disturbances. There were no sphincter disfunction associated. Physical examination noted a flask paraplegia, with abolition of deep tendon reflexes and a L1 sensitive level. Spinal MRI revealed a single well-limited right posterior lesion at the level of L1-L2. The patient underwent urgent surgery and the lesion was completely removed. The patient improved after surgery and was symptom-free after physical therapy. Pathological exam was in favor of a Primary neuroectodermal tumor. Conclusion: Primary neuroectodermal tumor is a malignant tumor that rarely develops in the spine. Prognosis remains poor despite progress in medical treatment.

631

P645: Primary Spinal Glioblastoma

Khalil Ayadi ¹ , Asma Bouhoula ¹ , Khalil Ghedira ¹ , Sofiene Bouali ¹ , Khansa Abderrahmanr ¹ , and Jalel Kallel ¹

¹ National Institute of Neurology, Neurosurgery, Tunis, Tunisia

Introduction: Primary neuroectodermal tumor is a malignant neural crest tumor. It usually develops in the brain in children and young adults. Secondary localization in the spine is possible through the cerebrospinal fluid. However, a primary localization is rare. Material and Methods: We report the case of a young patient who was treated for a primary neuroectodermal tumor located in the lumbar spine, in the department of neurosurgery in the Habib Bourguiba hospital in Sfax, Tunisia. Results: The patient is a 33-year-old man. He had no previous medical history. He was complaining of lower back pain for 6 months. He was admitted to our department for sudden exacerbation of the pain with walking disturbances. There were no sphincter disfunction associated. Physical examination noted a flask paraplegia, with abolition of deep tendon reflexes and a L1 sensitive level. Spinal MRI revealed a single well-limited right posterior lesion at the level of L1-L2. The patient underwent urgent surgery and the lesion was completely removed. The patient improved after surgery and was symptom-free after physical therapy. Pathological exam was in favor of a Primary neuroectodermal tumor. Conclusion: Primary neuroectodermal tumor is a malignant tumor that rarely develops in the spine. Prognosis remains poor despite progress in medical treatment.

644

P646: Sciatica Caused by Dorsal Meningioma

Khalil Ayadi ¹ , Fatma Kolsi ¹ , Anis Hachicha ¹ , Mansour Khrifech ¹ , Brahim Kammoun ¹ , and Boudawara Mohamed Zaher ¹

¹ Habib Bourguiba University hospital, Neurosurgery, Sfax, Tunisia

Introduction: Meningioma is usually a benign tumor of the central nervous system. It can be located in the spine in 25% of the cases and the symptoms are related to spinal cord compression. In very few cases they can be responsible for sciatica. Material and Methods: We report the case of a patient who was admitted for sciatica that was caused by a dorsal meningioma. The patient was treated in the department of neurosurgery in Habib Bourguiba hospital in Sfax, Tunisia. Results: A 46-year-old woman consulted for right sciatica. She had no previous medical history. The sciatica had S1 trajectory and started 10 months before admission. The pain was constant and did not respond to medical treatment. Physical examination was normal. A medullary MRI was performed. It revealed an intradural extramedullary lesion at T5-T6 level. The patient underwent surgery and the mass was completely removed. Pathology concluded that it was a meningioma. The pain disappeared immediately after surgery. Conclusion: Sciatica caused by a dorsal meningioma is a rare situation. A long delay separates symptoms and diagnosis. Surgery is the treatment in order to relive the suffering.

649

P647: Is There an Optimal Timing Between Radiotherapy and Surgery to Reduce Wound Complications in Spinal Metastases? A Systematic Review

Sirisha Madhu ¹ , Jiong Hao Tan ¹ , Keith Gerard Lopez ¹ , Balamurugan Vellayappan ² , and Naresh Kumar ¹

¹ National University Health System, Singapore, Singapore

¹ National University Health System, Singapore, Singapore

Introduction: Surgery with radiotherapy (RT) is more effective in treating spinal metastases, than RT alone. However, RT administered in close proximity to surgery may predispose to wound complications. Limited guidelines exist on the optimal timing between RT and surgery. The aim of this systematic review was to address whether pre-operative RT (preop-RT) and/or post-operative RT(postop-RT) is associated with wound complications and to define the safe interval between RT and surgery or vice versa. Materials and Methods: We conducted a systematic review of the published literature, with the following inclusion criteria: (i) Articles in English (ii) Patients with age ≥18 years (iii) Articles dealing with spinal metastases, treated with surgery and RT (preop-RT and/or postop-RT). The databases used for our search included PubMed, Scopus and Embase. The MeSH terms included in the search criteria were spine, neoplasms, neoplasm metastasis, laminectomy, surgery, radiotherapy, wounds and injuries, wound healing, and wound infection. The free text words included spinal, vertebra, cancer, malignancy, metastasis, vertebrectomy, corpectomy, radiation therapy, irradiation, stereotactic, wound problem, wound complication, wound dehiscence, major wound complication, and wound breakdown. The MeSH terms and free text words were combined systematically using relevant Boolean operators to develop search strings for conducting our search in the selected databases (up to February 2019). We obtained 664, 165 and 1503 articles from PubMed, Scopus and Embase, respectively, adding up to 2332 articles. After applying exclusion criteria and reading the titles and abstracts, we obtained 60 relevant articles. Further removal of duplicates resulted in 46 articles. We screened the full text of 46 articles and shortlisted 27 articles for data extraction. Fourteen additional articles were identified by hand-search, leading to a total of 41 articles, which have been included in this systematic review. Results: All 41 articles mentioned wound complications/healing. Sixteen articles discussed preop-RT, 8 postop-RT, 15 both, and 2 mentioned intraoperative-RT with additional pre/postop-RT. Out of the 17 articles that mentioned the RT type, 5 reported the use of stereotactic body radiation therapy (SBRT), 4 conventional external beam radiation therapy (cEBRT), and 8 both cEBRT and newer RT modalities such as SBRT and intensity-modulated radiotherapy(IMRT). Twenty studies mentioned surgery-RT time interval; where only one article concretely concluded that radiation-surgery interval of ≤7 days led to high wound complication rates. Another article highlighted the safety and feasibility of pre-operative SBRT followed by surgical stabilisation of spinal metastases within 24-hours with no wound complications. Seven studies reported significant association between RT and wound complications. Of these, 4 studies observed a higher risk of infection in patients receiving preop-RT when compared to postop-RT. Conclusion: The findings of this systematic review do not provide sufficient evidence to draw definite guidelines about the optimal radiation-surgery interval. However, based on published literature and expert opinions available, we conclude that an interval of 2 weeks with a minimum of 7 days is optimum between RT and surgery or vice versa; this can be reduced further by SBRT. If the RT-surgery window is >12 months, wound-complications rise. Postop-RT has fewer wound complications versus preop-RT.

656

P648: Staged Posterior Instrumented Decompression and Vertebral Excision Followed by Anterior Reconstruction in Aggressive (Enneking 3- S3) Thoracic Hemangiomas

Dilip Chand Raja Soundararajan ¹ , Shanmuganathan Rajasekaran ¹ , Ajoy P Shetty ¹ , and Rishi Kanna ¹

¹ Ganga Medical Centre and Hospitals Pvt Ltd, Spine Surgery, Coimbatore, India

Introduction: Aggressive hemangiomas are best managed surgically owing to severe spinal cord compression and Neurodeficit. Excessive bleeding and high rate of complications during the procedure has made surgeons to choose alternatives such as radiotherapy, stereotactic surgery and Vertebroplasty, with inherent limitation of residual or recurrent hemangiomas. Till date, there is no literature on staged excision and reconstruction of aggressive hemangiomas. The aim of the study was to analyze the outcomes of staged surgical decompression and excision in aggressive thoracic hemangiomas and discuss their advantages and disadvantages in comparison to other standard procedures described. Materials and Methods: Patients with definitive diagnosis of aggressive haemangiomas managed in a single institution and surgeon were included in the study. All patients underwent preoperative embolization and posterior instrumented decompression surgery usually spanning two levels above and below the level of lesion. Three days later they underwent anterior total vertebral excision and reconstruction. Eight patients who completed two years of clinical follow up were analysed for their outcomes. Basic demographic data, clinical and radiological findings, surgical procedure related data and their outcomes were analysed. Results: Eight patients (7 Females, 1 Male) with a mean age of 44.12 ± 15.37 years had undergone this staged surgical procedure. All patients had neurological deficits and according to Frankel grade- 4 patients had Frankel Grade D, 2 had Frankel Grade C and one each had Frankel Grade A and B. The mean duration of symptoms before presentation was 12.87 weeks (Range, 1-64 weeks). The levels affected included T1 (1), T2 (2), T8(1), T10(1), T11(1) and T12(2). Average duration of surgical procedure (including two stages) was 212.87 ± 59.23 minutes and the estimated blood loss was 1238.37 ± 337.26 ml. Among the eight patients 3 had pathological fractures, all except one had epidural soft tissue component of tumour. Anatomical involvement of vertebra haemangioma according to Tomita’s classification was Type 5 in 3 patients and Type 4 in 5 patients. The mean follow up duration of these patients was 46 ± 19.93 months. There were no recurrences until last follow up in all these patients. The Mean preoperative ODI score of 60.5 ± 9.937 improved to 13 ± 10.1 (P value <.0001). The Mean preoperative Numeric Pain Rating Score of 7.12 ± .97 improved to 1.37 ± .48 following surgery. All except one patient had Frankel E on final follow up. There were no cases of recurrence. Conclusion: Our results show that staging the complex vertebral excision resulted in lesser blood loss and total perioperative blood transfusions. Staged posterior instrumented decompression, anterior vertebral excision and reconstruction helps in addressing aggressive haemangiomas with severe neurological deficits safely and effectively as evidenced by the post-operative outcomes.

660

P649: Aggressive Pleomorphic Sarcoma of Thoracic Spine - A Rare Spine Tumour With Diagnostic, Surgical and Therapeutic Challenges

Dilip Chand Raja Soundararajan ¹ , Shanmuganathan Rajasekaran ¹ , Ajoy P Shetty ¹ , and Rishi Kanna ¹

¹ Ganga medical Centre and Hospitals Pvt Ltd, Spine Surgery, Coimbatore, India

Introduction: High grade pleomorphic sarcomas of spine have been rarely reported and have posed a significant diagnostic challenge to the radiologist, pathologist as well as surgeon. There is a scarcity of literature on therapeutic solution to these aggressive tumours which generally have been claimed to have poor prognosis. This is to report the clinical presentation, radiological and histopathological findings in a case of pleomorphic sarcoma of thoracic spine and discuss the therapeutic options of this rare tumour. Materials and Methods: A 22-year-old young male presented to us with thoracolumbar pain for past 6 months increasing in intensity over 1 month, associated with soft tissue swelling of the back and sudden onset neurological deficit since two days. Plain radiography showed ‘winking owl sign’ of T12 vertebra and MRI revealed a massive left sided para spinal soft tissue mass involving T11.T12 and L1 vertebra with extension into spinal canal and maximal spinal cord compression at T12 level. Considering the age and severe spinal cord compression and sudden onset Neurodeficit, (Frankel C) immediate tumour debulking surgery, spinal canal decompression along with posterior instrumented stabilization (T9-L3) was performed. Massive bleeding of 2483 ml was observed and the surgery was staged for residual tumour removal. In the immediate post-operative period, neurological status improved to Frankel D. Histopathological studies revealed an aggressive lesion of Primitive Neuroectodermal tumour with a differential diagnosis of Pleomorphic sarcoma and the patient underwent pre-operative embolization before tumour clearance surgery. IHC studies confirmed the diagnosis of Pleomorphic Sarcoma of Thoracic Spine. Results: Post-operative tumour therapy included daily regime of high dose external beam radiotherapy of 60 Gray in 30 fractions and Post radiation PET-CT revealed decrease in size of residual soft tissue tumour with residual activity. However it showed increased uptake in left knee synovium suggestive of metastasis. AIM regimen (Adriamycin-50 mg, Ifosfamide-6000 mg and Mesna-7500mg) was initiated and 6 cycles of chemotherapy for residual tumour activity and metastasis was performed. Follow up PET-CT showed good response with no activity in synovium and decreased activity in the spinal lesion. Neurology recovered completely and the patient remained asymptomatic till one year following surgery. A repeat PET –CT done at 2 years follow up showed increase in extent and activity of the spinal lesion with new metabolically active sub pleural lymph nodes suggestive of progressive disease. Radiotherapy and Chemotherapy have been re-initiated and the patient is under treatment. Conclusion: Despite complete neurological recovery and initial response to radiotherapy and chemotherapy, the disease progressed and there is no available method which could treat this aggressive pleomorphic sarcoma.

669

P650: Long Term Outcome of Spino-Pelvic Reconstruction After Total Sacrectomy for En-Bloc Resection in a Rare Case of Giant Sacral Chordoma

Dilip Chand Raja Soundararajan ¹ , Shanmuganathan Rajasekaran ¹ , Ajoy P Shetty ¹ , and Rishi Kanna ¹

¹ Ganga Medical Centre and Hospitals Pvt Ltd, Spine Surgery, Coimbatore, India

Introduction: Sacral chordomas are malignant bone tumors which are local invasive and generally have poor prognosis. The insidious onset and spread along critically neural and bony structures along with massive size of tumour at presentation and poor margination at presentation present a significant challenge to the surgeon in obtaining clear margins. Local recurrence is the most important predictor of mortality in patients with chordoma, demanding appropriate extent of initial resection. We present a rare case of giant sacral chordoma in a young male and its successful management. Methods: A 37-year-old male presented with six-month duration of chronic back pain and weakness of bilateral foot associated with bowel and bladder disturbances for 2 months. Radiological features were diagnostic of a massive sacral chordoma with severe bony destruction proximally extending to S 1 vertebra. Keeping in mind the young age and the proximal extent of the tumour, a wide resection was planned. Results: For a wide resection, this patient required total sacrectomy. Anterior retroperitoneal exposure was performed, and bilateral internal iliac arteries were ligated. Ureters were identified, reflected and safely protected after which rectum was mobilized and a clear space was created between rectum and sacrum. L5-S1 Discectomy was performed and released from the anterior aspect. A cotton pad was kept in the space to enable mobilization of the sacrum from posterior aspect. An ileostomy was performed, followed by posterior lumbosacral fixation. Decompression and Cauda Equina suturing was performed. A modified Osaka technique was then used to complete sacrectomy. The cotton pad was removed, and pelvic reconstruction was performed using fibular autograft and compression was applied across the construct. Total estimated blood loss was 1300 ml and post-operative period was uneventful. Ileostomy was closed after a week and bowel and bladder rehabilitation were initiated. Five year follow up has been completed with no recurrence. Conclusion: Surgical margins determine the prognosis in management of sacral chordomas and the surgeon should not be hesitant to perform a total sacrectomy which gives good results without additional complications. Pelvic reconstruction using cross connectors and fibular autograft is an effective way to provide stability following total sacrectomy.

719

P651: Thoracic Myelopathy Caused by Ossification of the Ligamentum Flavum: A Report of 33 Cases

Mohamed Badri ¹ , Kais Maamri ² , Mourad Masmoudi ¹ , Ghassen Gader ¹ , Mouna Rkhami ¹ , Kamel Bahri ¹ , and Ihsen Zammel ¹

¹ El Manar-Tunis university, Faculty of Medicine of Tunis, Department of Neurosurgery, Burns and Trauma Center, Ben Arous, Tunisia

² Fattouma Bourguiba University Hospital, Department of Neurosurgery, Monastir, Monastir, Tunisia

Introduction: Thoracic myelopathy caused by Ossification of the ligamentum flavum (OLF) is a rare entity, most evident in East Asia. The authors studied the clinical manifestations, radiological aspects, surgical treatment, and pathogenesis of this disease in a North African series. Material and Methods: Data obtained in 33 patients who underwent laminectomy for thoracicmyelopathy caused by OLF were studied retrospectively. Results: There were 26 men and 7 women who ranged in age from 38 to 76 years. The severity of myelopathy varied. Paraplegia was seen in 7 cases. Compression of the upper and middle third of the thoracicspine was evident in 9 cases and of the lower third in 24 cases. Multilevel OLF was demonstrated in 23 cases. In most cases, the OLF appears as a V-shaped lesion on axial images. Laminectomy was limited to the levels of compression, and the ligamentum flavum was drilled in all cases. The symptoms and signs improved in 23 cases and stabilized in 8 cases. In 2 cases symptoms recurred as a result of ossified lesions forming at other sites. No patients experienced kyphotic deformity. Histological examination showed that the mode of development of the ossified ligaments was endochondral ossification. Conclusion: The incidence of OLF seems to be relatively high in North Africa. An early laminectomy limited to the level of compression with careful drilling of the OLF is recommended. Patients with a shorter preoperative duration of symptoms and milder myelopathy experienced better neurological outcome.

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P652: Cauda Equina Paraganglioma: Clinical Presentation and Radiologic Aspects

Mohamed Badri ¹ , Mourad Masmoudi ¹ , Kais Maamri ² , Ghassen Gader ¹ , Mouna Rkhami ¹ , Kamel Bahri ¹ , and Ihsen Zammel ¹

¹ El Manar-Tunis university, Faculty of Medicine of Tunis, Department of Neurosurgery, Burns and Trauma Center, Ben Arous, Tunisia, Ben Arous, Tunisia

² Fattouma Bourguiba University Hospital, Department of Neurosurgery, Monastir, Tunisia, Monastir, Tunisia

Introduction: Paraganglioma is a benign neuro-endocrine neoplasm mainly found in the head, the neck, the mediastinum and the retroperitoneum. Cauda equina is a rare localization of this tumor. It is frequently misinterpreted with neurinoma and epndymoma in this site. Materials and Methods: We report a case of cauda equina paraganglioma. Clinical and radiologic findings were collected and analyzed. Results: A 50-year old male without medical history presented with progressive development of motor weakness in his lower extremities and urinary leakage. For one year, he had experienced severe lower back pain associated to bilateral radicular claudication of the lower limbs. Physical examination revealed stepping with bilateral foot weakness. Deep-tendon reflexes were abolished in both lower limbs with hypoesthesia of the lower left extremity. Magnetic resonance imaging (MRI) of the lumbar spine showed a multilevel high intensity epidural mass lesion compressing the dural sac extending from L1 to L5 level. The patient was operated. Laminectomy and epidural decompression at L3, L4 and L5 levels with removal of epidural fat was performed. Pathologic examination concluded to a cauda equine paraganglioma. Postoperative examination showed improvement of clinical signs. Conclusion: Cauda equina paragagliomas are rare tumors. They have non specific radiologic aspects on MRI. They have a good prognosis if correctly and rapidly treated. Surgery is its main treatment. Complete removal of this tumor is possible despite the hemorrhagic aspect of the tumor and recurrence is rarely noticed.

791

P653: Development of an Eight Item Spine Oncology Study Group Outcomes Questionnaire (SOSGOQ-8D)

Markian Pahuta¹, Felicity Fisk¹, Anne L. Versteeg², Charles Fisher³, Arjun Sahgal⁴, Ziya Gokaslan⁵, Laurence Rhines⁶, Stefano Boriani⁷, Chetan Bettegowda⁸, and Nicolas Dea³

¹ Henry Ford Health System, Detroit, USA

² Utrecht University, Utrecht, The Netherlands

³ University of British Columbia, Vancouver, Canada

⁴ University of Toronto, Toronto, Canada

⁵ The Warren Alpert Medical School of Brown University, Providence, USA

⁶ The University of Texas MD Anderson Cancer Center, Houston, USA

⁷ IRCCS Istituto Ortopedico Galeazzi, Milano, Italy

⁸ Johns Hopkins University School of Medicine, Baltimore, USA

Introduction: The AOSpine Knowledge Forum Tumor (developed the spine oncology‐specific outcome composite measurement scale known as the SOSGOQ2.0, which has previously been demonstrated to be a valid and reliable tool for measuring patient reported health related quality-of-life (HRQOL). Unfortunately, no mapping of SOSGOQ2.0 to utilities currently exists. Guidelines have been published for mapping composite measurement scales such as SOSGOQ2.0 to utilities. The ability to calculate quality-adjusted life-years (QALYs) for metastatic spine disease would enhance treatment decision making and facilitate economic analysis. The purpose of this study was to shorten the SOSGOQ2.0 to an eight-item questionnaire (SOSGOQ-8D) that would be better suited for developing a utility mapping. Material and Methods: SOSGOQ responses obtained from the Epidemiology, Process and Outcomes of Spine Oncology (EPOSO) and Metastatic Tumor Research and Outcomes Network (MTRON) studies were used in a hybrid concept-retention and factorial analysis shortening approach. To maintain content validity and clinical relevance, all four neurologic function single questions (legs, arms, bladder, and bowel) were retained. Confirmatory factor analysis was used to identify candidate items from the physical function, pain, mental health and social function domains. Poisson regression was used to identify the optimal combination of items. Results: All 4 neurologic function single questions (leg weakness, arm weakness, bladder dysfunction, bowel dysfunction) were retained to maintain content validity and clinical relevance. CFA using the MTRON training set demonstrated adequate model fit and confirmed the structure of non-neurologic SOSGOQ2.0 domains. All items were clinically relevant with factor loadings greater than .50. The highest loading items were: limitations in activities of daily living and limitations in travelling from home for the physical function domain; mobility limitation from pain and overwhelming pain for the pain domain; impaired concentration and impaired relationships from the social function domain. Poisson regression models for all combinations of candidate SOSGOQ-8D domain questions provided excellent fit of the EPOSO validation set with pseudo-R² values for all models greater than .75. The regression model with the lowest rank sum consisted of SOSGOQ2.0 items 3, 13, 16, and 19. Conclusion: We have developed an 8 item Spine Oncology Group Outcomes Questionnaire – 8 Domain (SOSGOQ-8D) by formally shortening the SOSGOQ2.0 in accordance with published guidelines. A shortened questionnaire is needed to facilitate mapping of utilities to patient reported outcomes in metastatic spine disease for QALY calculation. In order to keep all four neurologic single items, it was necessary to select a single item from the physical function, pain, mental health, and social function domains that sufficiently covered the dimension. Our analysis indicates that in addition to each of the neurologic single items from the SOSGOQ2.0, the SOSGOQ-8D should include:

- SOSGOQ2.0 item 3: “Does your spine limit your ability to care for yourself?”

- SOSGOQ2.0 item 13: “How much has your pain limited your mobility (sitting, standing, walking)?

- SOSGOQ2.0 item 16: “Have you felt depressed?”

- SOSGOQ2.0 item 19: “Do you feel that your spine condition affects your personal relationships?”

868

P654: Readmission-Free Survival Analysis in Metastatic Spine Tumour Surgical Patients: A Novel Concept

Naresh Kumar ¹ , Andrew Thomas ¹ , Miguel Rafael Ramos ¹ , Yong Hao Joel Tan ¹ , Liang Shen ² , Sirisha Madhu ¹ , Keith Gerard Lopez ¹ , Jiong Hao Tan ¹ , and Balamurugan Vellayappan ³

¹ National University Health System, Singapore, Singapore

² National University of Singapore, Singapore, Singapore

¹ National University Health System, Singapore, Singapore

Introduction: Outcomes commonly used to ascertain success of metastatic spine tumour surgery (MSTS) are 30day complications/mortality and overall/disease-free survival. We believe a new effective outcome indicator after MSTS would be the absence of unplanned hospital readmissions (UHR) after index-discharge. We introduce the concept of “readmission-free survival” (ReAFS), defined as ‘the time duration between hospital discharge after index-operation and first UHR/death’. We postulate that an ideal ReAFS should be equal to remaining life expectancy of the patient after index-surgery. The aim of our study was to identify factors influencing ReAFS in MSTS-patients. Materials and Methods: We retrospectively analysed 266 consecutive patients (age ≥18 years) who underwent MSTS between 2005 and 2016 with a follow-up for a minimum of 2years or until their demise, whichever was earlier. Approval was obtained from Institutional Review Board prior to study commencement. Demographics, oncological characteristics, procedural, preoperative, and postoperative details were collected. ReAFS of patients within two-years or till demise, were reviewed. Perioperative factors predictive of prolonged ReAFS were evaluated using multivariate regression analysis. Results: A total of 230-patients met criteria for analysis. The mean age was 60.1 ± 11.8 years; 47.8% were females. Mean preoperative haemoglobin was 11.93 ± 1.96 g/dL. Majority had at least two preoperative comorbidities. Median Tokuhashi score was 8. An Eastern Cooperative Oncology Group Performance Status (ECOG-PS) score of 1 was observed in 38.8% of patients. Majority of primary tumours were lung followed by breast, and haematological. 74% of the cohort underwent open surgery with a median of five levels instrumented and one level decompressed. Of the 230-patients, 201 had an UHR or died during the study period, whilst one in eight (29/230) had no UHR. Initial univariate (Kaplan-Meier) analysis revealed that patients with preoperative haemoglobin >12g/dL had a median ReAFS of 182 days (95% CI 82.8–281.1) while those with <12 had a median of 66 days (40.5-91.4) (P = .005). Patients with ECOG <3 had a median ReAFS of 138 days (90.9–185.0), versus 30days (0-75.7) for those with ECOG >3 (P < .001). Patients who underwent preoperative radiotherapy had a median ReAFS of 48 days (22.5-73.5) while those without preoperative RT had 134 days (84.2-183.7) (P = .016). Metastatic spine disease from primary lung tumours had the shortest ReAFS of 51 days (21.9-80.0). Conversely, having breast or prostate primaries had average ReAFS of 230 days (49.4-410.5) and 322days (.0-677.3), respectively (P = .004). An ReAFS of 111 days (63.5-158.5) was observed when comorbidities were <4, as opposed to 47 days (18.8-75.2) when comorbidities exceeded 4 (P = .062). Multivariate analysis revealed that preoperative haemoglobin ≥12 g/dL (P = .029); ECOG score of ≤2 (P = .026); primary breast (P = .003) and haematological (P < .001) cancers; comorbidities ≤4 (P = .030); absence of preoperative radiotherapy (P = .033); and a shorter postoperative length of stay (P = .025) significantly prolonged the ReAFS. Conclusion: Readmission-free survival is a novel concept in MSTS, which relies on patient’s general condition, appropriateness of interventional procedures, and underlying disease burden. Additionally, it may indicate the successful combination of a multi-disciplinary treatment approach. This information will allow oncologists and surgeons to identify patients who may benefit from increased surveillance following discharge to increase ReAFS. We envisage that ReAFS is a concept that can be extended to other surgical oncological fields.

916

P655: CT Body Composition Assessment as Predictors for Postoperative Outcomes in Patients With Spinal Metastases

Olivier Groot ^1,2 , Michiel Bongers ¹ , Colleen Buckless ³ , Peter Twining ¹ , Neal Kapoor ¹ , Joseph Schwab ¹ , Martin Torriani ³ , and Miriam Bredella ³

¹ Massachusetts General Hospital, Orthopaedics, Boston, USA

² University Medical Center Utrecht, Orthopaedics, Utrecht, The Netherlands

³ Massachusetts General Hospital, Radiology, Boston, USA

Introduction: The survival of patients with spinal metastases has improved substantially due to improvements in systematic therapy. However, reliable biomarkers are lacking as to whether surgery will maximize patient’s function and quality of life. The implementation of the criteria for Spinal Instability in Neoplastic Disease (SINS) and the Neurologic, Oncologic, Mechanical, and Systemic (NOMS) decision framework have guided orthopaedic surgeons in these decisions, but accurate survival prediction remains challenging. CT assessment of body composition can assess patient frailty and has been related to survival in patients with and without cancer. However, the predictive value of body composition measurements on postoperative outcomes in patients with metastatic spine disease is unknown. Our study questions were: (1) Do preoperative CT body composition measurements predict survival in patients with spinal metastases undergoing surgery? (2) Is there an association between body composition and length of stay (LOS), postoperative complications within 30 days, and the need for reoperation? Materials and Methods: A retrospective search was performed to identify patients with spinal metastases (including lymphoma and multiple myeloma) who underwent surgery at a single tertiary research center between 2001 and 2016. Inclusion criteria were age ≥18 years and a diagnostic CT of the abdomen within three months prior to surgery. All CT quantification and attenuation measurements were performed at L4. Quantifications of cross-sectional areas of abdominal subcutaneous adipose tissue (SAT), visceral adipose tissue (VAT), and paraspinous muscles was performed on CTs with and without administration of contrast. CT attenuation measurements in Hounsfield Units (HU) of abdominal fat depots and muscle were performed in patients who had contrast-enhanced CTs in the portal-venous phase. Univariate and multivariate Cox Proportional-Hazards analyses determined the associations between body composition and 90-day and 1-year survival. Univariate and multivariate logistic regression were used to test associations between pre-operative variables and LOS, postoperative complications, and reoperation. Results: We included 196 patients with a median age of 62 years (IQR = 53-70). The most common primary tumors were renal cell (14%), lung (13%), and breast (7.7%). Survival rates for 90-day and 1-year were 76% and 46%, respectively. Sarcopenia was associated with decreased survival for both timepoints (P < .044 and P < .041, respectively) after controlling for sex, age, BMI, Charlson Comorbidity score, primary tumor type, visceral metastases, and duration between diagnosis of spinal metastases and surgery. Fatty infiltration of muscle was associated with longer LOS (P < .001, OR: .90). Greater SAT attenuation (HU) was associated with increased LOS (P = .001, OR: 1.05). Lower muscle area was associated with a higher rate of postoperative complications within 30 days of operation (P < .001, OR: .98). SAT area was associated with a lower risk of reoperation (P = .012, OR: .99) after controlling for sex, age, BMI, Charlson Comorbidity score, primary tumor, visceral metastases, and duration between diagnosis of spinal metastases and surgery. Conclusions: Body composition assessed by CT may serve as an imaging biomarker for survival in patients with spinal metastases. These body composition parameters may also be useful to predict LOS, likelihood of postoperative complications and risk of reoperation.

926

P656: Spinal Clear Cell Meningioma Without Dural Attachment: Case Report and Review of Literature

Kais Maamri ¹ , Mohamed Amine Hadj Taieb ¹ , Mahmoud Ben Messaoud ¹ , Nessrine Nessib ¹ , Maher Hadhri ¹ , Mohamed Badri ² , and Mehdi Darmoul ¹

¹ Fattouma Bourguiba University Hospital, Monastir, Tunisia

² National Institute of Neurologie, Mongi ben Hmida, Tunis, Tunisia

Introduction: Clear cell meningioma (CCM) is a very rare histologic subtype of meningioma usually affecting younger patient. Material and Methods: A 58-year-old female patient was presented to our department with pain in her lower back and bilateral sciatica for 6 months. Magnetic resonance imaging (MRI) showed an intra-dural lesion at L3 measuring 31 mm of height. The mass was well demarcated and had an iso-intense signal on T1 and a hyperintense signal on T2 with intense and homogeneous gadolinium enhancement. We operated the patient via a posterior approach. A total resection was possible due to lack of dural adhesion of the tumor. Histologic diagnosis was clear cell meningioma. Patient’s recovery course after the operation was uneventful. We tried to collect all the cases of CCMs than have been reported in the English language studies in order to understand this rare type of meningiomas, its differences with the conventional meningiomas and the modalities of treatment. Results: CCMs are a rare subtype of meningiomas. Until 2019, less than 100 cases of spinal CCMs have been reported, 19 of them had no dural attachment. For spinal CCMs, the most affected location was the lumbar region. Gross total resection is recommended in treating spinal CCM whenever possible. However, the value of postoperative radiotherapy has been increasingly affirmed especially in younger patient who had a subtotal resection. Spinal CCMs are more aggressive, with a much greater progression rate (38.0%) after initial treatment compared with ordinary spinal meningiomas (∼3%). Conclusion: Spinal CCM, a rare subtype of meningiomas is an aggressive neoplasm with a high rate of local recurrence.

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P657: Intramedullary Spinal Cord Metastasis From Ovarian Cancer

Kais Maamri ¹ , Mohamed Amine Hadj Taieb ¹ , ines cherif ¹ , Mohamed Boukhit ¹ , Atef Ben Nsir ¹ , Mohamed Badri ² , and Mehdi Darmoul ¹

¹ Fattouma Bourguiba University Hospital, Neurosurgery, Monastir, Tunisia

² National Institute of Neurologie Mongi ben Hmida, Neurosurgery, Tunis, Tunisia

Introduction: Intramedullary spinal cord metastasis (ISCM) from ovarian cancer is rare. Only few case reports have been published previously. Currently there is no generalized approach to treating patients with intra-medullary spinal metastasis. High cervical spinal cord lesions can be particularly challenging cases. Material and Methods: Herein, we present a case of a patient who was treated for papillary ovarian adenocarcinoma and was thought to be disease free for 2 years, then presented with quadriparesis with urinary retention. Imaging studies of her spine revealed a cervical intramedullary mass that extends from C6 to C7. Complete tumor removal was performed via a posterior approach. Pathologic analysis revealed histological and cytological features consistent with papillary ovarian adenocarcinoma. After surgery, the patient gained improvement in her limbs’ strength and was transferred to the rehabilitation service. Postoperative MRI showed complete resection of the tumor. Results: The intramedullary spinal cord is an unusual site of metastatic cancer. ISCMs represent 4.2-8.5% of central nervous system (CNS) metastases, less than 5% of spinal metastases, 1-3% of intramedullary tumors, and .6% of spinal cord tumors. Our case is, to the best of our knowledge, the second reported case of ovarian carcinoma (managed primarily with surgery) metastasizing to the cervical spinal cord. Conclusion: Due to improving systemic cancer therapies, patients with cancer now often survive longer and are more likely to develop central nervous system metastases. Therefore, neurosurgical oncologists are often challenged with difficult decisions about how to surgically manage these patients. We recommend individualized multidisciplinary management based on patient functional status, the need for definitive diagnosis for possible additional adjuvant therapies, and consideration of extent of systemic disease impacting on desirable quality and length of survival.

952

P658: Sacral Tumor: An Institutional Experience

Kais Maamri ¹ , Ines Cherif ¹ , Mohamed Amine Hadj Taieb ¹ , Mahmoud Ben Messaoud ¹ , Nessrine Nessib ¹ , Atef Ben Nsir ¹ , Mohamed Badri ² , and Mehdi Darmoul ¹

¹ Fattouma Bourguiba University Hospital, Neurosurgery, Monastir, Tunisia

² Trauma and Major Burns Center Ben Arous, Neurosurgery, Ben Arous, Tunisia

Introduction: Primary tumors of the sacrum are rare lesions and account for fewer than 7% of all spinal tumors. Metastatic lesions, multiple myeloma, and lymphoma are far more common than primary sacral tumors. Chordoma is the most common primary malignant sacral tumor, which represents 45% of all malignant spine tumors. Sacral lesions may be challenging because of nonspecific clinical features and diagnosis is often delayed. Materials and Methods: We retrospectively analyzed a clinical series of 10 sacral tumors treated between 1989 and 2019 in the department of neurosurgery of Fattouma Bourguiba University Hospital of Monastir Tunisia. Analysis comprised medical records, clinical imaging and surgical management with review of the current literature. Results: 10 patients were included. We reported 6 males and 4 females. The age ranged from 4 months to 76 years (mean 43.4 years). Bowel and bladder dysfunction and lombosciaticas were the most common symptoms and were both present in 40% of the patients. The mean delay of diagnosis is 1.44 year. All patients underwent an invasive procedure at least once. The most common malignant tumor was Chordoma (40%) and primary benign tumor was osteoblastoma (20%). The repartition of other tumors was: Lymphoma, Lipoma, Teratoma and Plasmocytoma (10% each). Infection in sacral chordoma was the most commun complication, seen in 2 cases. We noted 3 cases of death due to chordoma: all of them had a relapse of the cancer that occured early (from 6 months to 1 year). Postoperatively, significant symptoms improvement was achieved in all patients with benign tumors and only in 2 cases with malignant neoplasms. We noted a loco regional tumor extension in one case. The median survival of patients with malignant tumors was 3.2 years. Conclusion: Much more series of sacral tumors should be reported in order to optimize management and find out guidelines in order to achieve better outcomes.

Keywords

Sacral, tumor, surgery, malignant, benign

1050

P659: Positioning Issues of Spinal Tumor Surgery During Pregnancy

Alessandro Versace¹, Daniele Bongetta¹, Elena Virginia Colombo¹, Tommaso Calloni², Marilou Cavaliere², and Roberto Assietti¹

¹ ASST Fatebenefratelli Sacco, Milan, Italy

² Università di Milano Bicocca, Milan, Italy

Introduction: Albeit rarely, different spinal pathologies may require a surgical treatment during pregnancy. The management of such cases poses a series of challenges to the multidisciplinary team involved, beginning with an adequate positioning. No systematic review of the proposed positionings and related caveats during spinal surgery in pregnant women has been performed to date. Methods: We reviewed the literature for spinal tumor surgery-related positioning strategies during pregnancy. Moreover, we present an illustrative case of an innovative ¾ prone positioning employed for a mid-thoracic angiolipoma. Results: The surgical strategy may vary, based upon different factors, such as the location and the nature of the underlying pathology, the stage of the pregnancy as well as the clinical condition of mother and fetus. During the first trimester, we retrieved no particular limitation. During the second trimester, the habitus begins to raise issues about the abdominal and the aortocaval compressions. The third trimester implies also neonatal and ethical challenges. Fetal monitoring and possibility to urgently proceed to delivery should be guaranteed. Prone position is feasable during the second trimester, provided an adequate frame, but has been rarely employed in the third trimester. The lateral or ¾ prone positioning may offer the safest option in the latest stages of pregnancy. Supine and sitting positionings are anedoctal. Conclusions: In the absence of evidence-based algorithms or large case-series, several aspects of the management of spinal tumors during pregnancy should be carefully evaluated in the choice of a correct positioning. A multidisciplinary team composed of fetal-maternal physicians, obstetrics, spinal surgeons an anesthesiologists is strongly advised in oder to tailor an adequate positioning plan for each individual case.

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P660: Microscope-Assisted Mini-Tubular Surgery for Intraspinal Tumors: 265 Cases Report

Rui Wang ¹ , Zeyan Liang ¹ , Xinyao Chen ¹ , Xiongjie Xu ¹ , and Chunmei Chen ¹

¹ Fujian Medical University Union Hospital, neurosurgery, Fuzhou, China

Introduction: For intraspinal tumors, the classic operation is to open the whole lamina, remove the tumor, and fuse the fixation. However, the approach can not only cause muscle damage and incision pain, but also affect the mobility of the spine. Therefore, microscope-assisted mini-tubular surgery (MMTS) has been introduced to treat intraspinal tumors, which may be less tissue trauma, hoping to a faster rate of recovery. This study aims to systematically collect case data of intraspinal tumors resected through MMTS, and retrospectively analyze the safety and effectiveness of the operation. Material and Methods: We performed a retrospective review of 265 patients who underwent MMTS for intraspinal tumor and met inclusion criteria from March 2015 to December 2018. The primary outcomes, spinal function and pain, were assessed using modified Japanese Orthopedic Association (mJOA) scale and Visual Analogue Scale (VAS). Outcomes will be measured the day following surgery, at 1 week, and at 1, 3, 6 months after surgical treatment. In addition, we also collected follow-up imaging data (CT and MRI) within six months after surgery, and compared them with those before surgery. The data, including surgical complications, operation time, blood loss and length of stay, was also collected and analyzed. Statistical analysis was performed using Fisher exact test and t-test. Results: A total of 265 cases were collected, including 164 cases of Schwann cell tumors, 33 cases of metastatic tumors, 26 cases of meningiomas, 21 cases of neurofibromas, 12 cases of ependymomas, and 9 cases of cavernous hemangiomas. Among them, 80% were extramedullary subdural tumors, 13% were intraspinal tumors, and 7% were epidural tumors. After surgery, the mJOA and VAS scores were significantly improved from the first day after surgery (P < .05), and maintained until six months after surgery. There were 6 cases of cerebrospinal fluid leakage, and no patients shows infection or nerve damage. The operation time was (166.65 ± 22.73) min, the blood loss was (45.87 ± 15.45) ml, and the hospital stay was (8.09 ± 1.31) days. During the 6 months follow-up period, re-examination of MRI revealed no tumor recurrence, and re-examination of CT revealed no spinal deformity and instability. Conclusion: Compared with conventional operation, the advantages of MMTS include avoiding injuries of Muscles and ligaments, remove tumors totally and lower incidence of complications and instability. This procedure is a reliable technique for the treat.

1148

P661: Giant Solitary Osteochondroma of Cervical Spine Masquerading as Benign Neck Stiffness: A Rare Case for Diagnosis and Treatment

Aju Bosco ¹ and Nalli Ramanathan Uvaraj ¹

¹ Madras Medical College, Orthopedic Spine Surgery Unit, Chennai, India

Introduction: Osteochondroma or osteocartilaginous exostosis involving the axial skeleton is a very rare presentation. Only 1.3-4.1% of solitary osteochondromas originate in the spine. Spinal osteochondromas are generally easy to diagnose as they present with pain and rarely with features of neural compression. Herein, we present an interesting case of spinal osteochondroma with an atypical presentation which was diagnosed and managed successfully with a favourable clinical outcome. Materials and Methods: We describe an otherwise normal, 12-year-old female who presented with the sole complaint of restriction of neck extension during upward gaze. A meticulous clinical examination of her spine revealed a bony hard swelling on the posterior aspect of the mid-cervical spine. Her neurological examination was unremarkable. Plain radiographs revealed a giant exophytic lesion arising from the posterior elements of C5 vertebra. A detailed radiological evaluation with magnetic resonance imaging (MRI) and computed tomography (CT) scan revealed an exophytic osseous lesion arising from the spinous process and right lamina of C5 vertebra, with no extension into the spinal canal. Through a posterior midline approach, the lesion was meticulously dissected to identify its point of attachment to the C5 lamina. Using a high speed burr the lesion along with its cartilaginous cap was removed in toto with preservation of the posterior neural arch to prevent instability. Histopathological examination confirmed the diagnosis of osteochondroma. Outcomes were analyzed with respect to restoration of cervical spine extension and upward gaze, neck disability index (NDI) score, SF-12 score, and evidence of recurrence of lesion during follow-up. Results: In the immediate postoperative period, the patient was able to extend her cervical spine with restoration of upward gaze. At 28 months follow-up, the patient had good clinical and functional outcomes as evidenced by the significant improvement in neck disability index (NDI) and SF-12 scores. No complication was observed. Plain radiographs, MRI and CT scans taken at 27 months follow-up showed no recurrence of the lesion. Conclusion: A high index of suspicion, a meticulous clinical examination, and a detailed radiological evaluation is mandatory to clinch the diagnosis in patients presenting with restriction of cervical spine mobility, though they may be seemingly benign. Preoperative planning with a CT scan and MRI is mandatory to identify the pedicle of the osteochondroma and to identify the exact vertebra of origin to do a complete surgical excision of the lesion to prevent recurrence, without destabilizing the spine.

Keywords

spine, cervical, osteochondroma, neck stiffness, recurrence

1149

P662: Intramedullary Pilomixoid Astrocytoma: About a Case

Rihab Benfredj ¹ , Abdelhafidh Slimane ¹ , Ilyes Krifa ¹ , Nadhir Karmani ¹ , and Khansa Abderrahmane ¹

¹ Institute Of Neurology, Neurosurgery, Tunis, Tunisia

Introduction: Pilomyxoid astrocytoma (PMA) is a rare brain tumor. It was first reported in 1999. In 2007, it was recognized by the World Health Organization (WHO) as a distinct variant of astrocytomas and was designated WHO grade II. However, during the update of the WHO classification of 2016, the designation of a specific grade was withdrawn until more information was obtained. APMs can be distinguished from classical APs because of their monomorphic appearance, myxoid background, angiocentric structure, scarcity of Rosenthal fibers and rare eosinophilic granular bodies, as well as a tendency to be more aggressive. They also have a more aggressive clinical behavior, a higher rate of recurrence, and earlier dissemination into the cerebrospinal fluid. APM most often occurs in very young children and is frequently located in the hypothalamic/chiasmatic region unlike the medullary localization which is extremely rare. Only 14 cases of medullary MPA have been reported in the literature since its pathological description in 1999. Material and Methods: We report here another case of a spinal pilomyxoid astrocytoma in a 7-year-old child. We are also going to do a review of the literature in order to specify the various clinical aspects, to assess the contribution of imaging. Results: We report here another case of a spinal pilomyxoid astrocytoma in a 7-year-old child. We are also going to do a review of the literature in order to specify the various clinical aspects, to assess the contribution of imaging. Conclusion: Pilomixoid astrocytoma have an aggressive clinical behavior and earlier dissemination into the cerebrospinal fluid. APM most often occurs in very young children and is frequently located in the hypothalamic / chiasmatic region unlike the medullary localization which is extremely rare.

1164

P663: Aneurismal Bone Cist in C2. CASE Report

Luiz Claudio Rodrigues ¹ , Fernanda Andrea Minutti Navarro ² , Rodrigo Yuiti Nakao ² , and Daniela Antunes Krauthamer ³

¹ Faculdade Santa Marcelina, Ortopedic Surgery, São Paulo, Brazil

² Hospital Santa Marcelina, Spine Surgery, São Paulo, Brazil

³ Hospital Jardim Helena, CEO, São Paulo, Brazil

Introduction: Aneurysmal bone cyst is a benign, hypervascularized, aggressive behavior due to its progressive, destructive and compressive growth of adjacent structures. Its symptomatology is variable, being able to bring from pain to the patient, until neurological complaints, preferentially affecting long bones and vertebrae. Material and Methods: We report a case of aneurysmal bone cyst of the cervical spine, affecting adult men, presenting limitations of cervical movements and neurological alterations during the clinical follow - up. The diagnosis was established through radiography and computed tomography, and puncture biopsy was performed to rule out differential diagnoses. The patient was submitted to the surgical procedure for resection of the tumor and its affected vertebrae, in addition to the stabilization of the cervical spine. In this case, infusion of local intraoperative corticoid was performed as a method of association in order to reduce the risk of relapse. Results: The patient progressed satisfactorily, showing a significant improvement in the movement of the cervical spine and in the neurological picture, demonstrating efficacy in the Margel surgical technique for stabilization of the cervical spine, and in the transoral approach for resection of the tumor of cervical involvement. Conclusion: We discuss the treatment of choice in relation to all the existing ones, and the evolution of this patient.

1180

P664: Intradural Extramedullary Spinal Cord Tumors: A Retrospective Study of Surgical Outcomes

Pratik Patel ¹ and Dr Samir Dalvie ¹

¹ P D Hinduja National Hospital and Research Centre, Orthopaedic and Spine surgery, Mumbai, India

Introduction: Intradural-extramedullary spinal cord tumors (IESCT) accounts for approximately two-thirds of all intraspinal neoplasm and are of important clinical consideration and surgery is the essence in cases with neurological deterioration. Material and Methods: This study investigated thirty-one cases of intradural extra-medullary tumors that were treated surgically between 2012 and 2019. There were 15 females, 16 males with an average age of 50.8 years (19-87 years) and followed up for at least a year. The preoperative symptom with duration, tumor location, intradural space occupancy ratio, and the histopathological diagnosis were analyzed. Functional evaluation was evaluated by the Karnofsky-performance score and visual analogue scale (VAS) and the neurologic function was assessed by Frankel grade. Results: The tumours were located as, thoracic-18 (58.06%), lumbar-8 (25.80%), cervical-01 (3.22%), and junctional-04 (12.90%) (CervicoThoracic-02, Thoracolumbar-02). The histopathological diagnosis included schwannoma-16 (51.61%), meningiomas-11 (35.48%), lipoma-2 (6.45%), haemangioma-01 (3.22) and ependymoma-01 (03.22%). The VAS score was reduced in all cases from 8.64 (+1.23) to .93 (+.99) (P < .001), Karnofsky performance score was improved in all case from 56.45 (+8.77) to 93.87 (+6.15) and the Frankel grade was significantly improved with grade E-25 case (80.64%) and grade D-06 case (19.50%) at 1 year follow up. The preoperative neurological deficit improved within 8 postoperative weeks in most cases and within 1 postoperative year in all cases. Complications included cerebrospinal fluid leakage, paraesthesia, and recurrence (12.50%). Conclusion: Intradural-extramedullary tumors detected by MRI are mostly benign and good clinical results can be obtained when treated surgically. Aggressive surgical excision potentially minimizes neurologic morbidity and improved outcome. Cervical and upper dorsal involvement with anterior tumor location, high tumor occupancy ratio has a high chance of neurology involvement with poor functional outcomes.

1194

P665: Postoperative Outcomes of Minimally Invasive Pedicle Screw Fixation for Treatment of Unstable Pathologic Neoplastic Fractures

Matthew Chiin ¹ , Jacob Bruckner ¹ , Jael Camacho ¹ , Julio Jauregui ¹ , Daniel Cavanaugh ¹ , Eugene Koh ¹ , Daniel Gelb ¹ , and Steven Ludwig ¹

¹ University of Maryland School of Medicine, Department of Orthopaedics, Baltimore, USA

Introduction: Minimally invasive techniques have emerged as a useful tool in the treatment of neoplastic spine pathology due to a potential decrease in surgical morbidity and earlier initiation of adjuvant treatment. The objective of this study was to analyze outcomes and complications in a cohort of unstable, symptomatic pathologic fractures treated with percutaneous pedicle screw fixation. Material and Methods: A retrospective review was performed on consecutive patients that had spinal stabilization for unstable pathologic neoplastic fractures between 2007 and 2017. Patients who underwent percutaneous pedicle screw instrumentation through a minimally invasive approach were included. Indications for surgery included intractable pain, mechanical instability, and neurologic compromise in the setting of a radiographic lesion. Patients who had an anterior procedure or a mini-open decompression were compared to those with only percutaneous fixation. Results: 25 patients with a mean Tomita Score of 6.3 ± 2.1 [95% CI, 5.5-7.2] were treated with constructs that spanned an average of 4.4 ± 1.6 [95% CI, 3.7-5.1] instrumented levels. 10 patients were augmented with vertebroplasty, 5 were supplemented with anterior corpectomy, and 9 had accompanying mini-open incision for decompression. 13 patients (52%) had percutaneous fixation only. Median length of stay was 5 days (interquartile range 3.5-12.5) and median estimated blood loss was 200mL (interquartile range 100-475). Majority of patients (60%) had no complication during hospital stay and were discharged home (64%). Complications included two extracavitary corpectomies, one pathologic fracture at different levels, and one adjacent segment disease. Conclusion: Minimally invasive pedicle screw fixation seems to be a safe and effective option when treating unstable neoplastic fractures and can provide a viable alternative to open surgery in select cases.

1209

P666: Safety and Effectivenes of Spine Biopsy Under Local Anesthesia

Luiz Claudio Rodrigues ¹ , Rodrigo Yuiti Nakao ² , Fernanda Andrea Minutti Navarro ² , and Daniela Antunes Krauthamer ³

¹ Faculdade Santa Marcelina, Ortopedic Surgery, São Paulo, Brazil

² hospital Santa Marcelina, Spine Surgery, São Paulo, Brazil

³ hospital Jardim Helena, Ceo, São Paulo, Brazil

Introduction: Metastatic injuries to the spine are very common diseases and require further examination for their treatment. Spinal biopsy is a fundamental weapon in the diagnosis and therapeutic planning of these vertebral pathologies. Material and Methods: To evaluate the safety and effectiveness of spinal biopsy performed with local anesthesia. Twenty-four patients, 14 female and 10 male, with spinal injuries visualized by imaging exams such as computed tomography (CT) and magnetic resonance imaging (MRI) seen from January to December 2017, were studied. analyzed: effectiveness, safety and pain. Results: Biopsies were performed under local anesthesia, varying the transpedicular and paravertebral techniques, with a mean age of 43 to 81 years. Of the 24 patients studied, 06 had a positive result for adenocarcinoma metastasis, with 100% efficacy. Regarding pain, the visual analog scale (VAS) decreased substantially after the procedure, being higher in those patients with metastases. Regarding complications, we did not obtain any of them in our study. Conclusion: Spinal biopsy is a safe and practical method to obtain adequate material for the diagnosis of vertebral neoplasms and especially tolerable for the patient.

1218

P667: Comparison of Four Predictive Scoring Systems for Morbidity in Spine Oncological Surgery

Rafael De la Garza ¹ , Ishan Naidu ¹ , Jong Hyun Choi ¹ , Joshua Benton ¹ , Murray Echt ¹ , Vijay Yanamadala ¹ , and Reza Yassari ¹

¹ Montefiore Medical Center, Bronx, USA

Introduction: Estimation of survival has helped in the decision-making process to justify surgical intervention for patients with metastatic spinal tumors. However, estimation of perioperative morbidity is challenging. The objective of this study is to compare four scoring systems in their ability to predict perioperative morbidity in spine oncological surgery. Material and Methods: One-hundred and five patients who underwent surgery for metastatic spinal tumors at our institution between 2013 and 2019 were included in this study. All patients had scores retrospectively calculated using the New England Spinal Metastasis Score (NESMS), Metastatic Spinal Tumor Frailty Index (MSTFI), Anzuategui, and Spine Oncology Morbidity Assessment (SOMA) scoring systems. The main outcome measure was development of a medical complication (minor or major) within 30 postoperative days. The predictive ability for each system was assessed using receiver operating characteristic (ROC) analysis and calculations of the area under the curve (AUC) to quantify predictive accuracy. Results: The overall 30-day complication rate was 36.2% and the rate of major complications was 19.1%. Among all patients who underwent spine oncological surgery, the SOMA score had the highest AUC for 30-day overall (AUC .75; 95% CI, .66-.84) and major morbidity (AUC .73; 95% CI, .61-.85). This was followed by the NESMS with an AUC of .59 (95% CI, .47-.70) for all complications and .66 for major complications (95% CI, .51-.81). Conclusion: Among four scoring systems, the SOMA score had the highest accuracy in predicting overall and major complications in this study, followed by the NESMS. Future prospective validation of these systems is encouraged, but these tools may prove useful for preoperative risk stratification and patient counseling in oncological spine surgery.

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P668: Surgical Excision of Osteoid Osteoma of Lumbar Spine With Ultrasonic Bone Scalpel - Technical Note

Munjal Shah ^1,2 , Arjun Dhawale ^2,3 , and Abhay Nene ^1,2

¹ Lilavati Hospital and Research Centre, Orthopaedic spine, Mumbai, India

² Bai Jerabai Wadia Hospital for Children, Pediatric Orthopaedic Spine, Mumbai, India

³ Sir HN Reliance Foundation and Research Centre, Orthopaedic Spine, Mumbai, India

Introduction: Osteoid osteoma is a benign bone tumour. Osteoid osteoma constitutes 10.8% to 13.5% of all primary benign bone tumors. However, spinal involvement is infrequent and only 10% cases of primary osteoid osteoma involves spine. Posterior elements of spine are most common site. Radiofrequency ablation or CT guided drilling are not very safe options close to the dura. Complete surgical resection is needed to prevent the recurrence in osteoid osteoma. Disadvantage is removal of normal bone sometimes to achieve complete resection and can create iatrogenic instability in spine if the facet is damaged which might require fusion. With use of ultrasonic bone scalpel precise bone can be removed and can hence chance of creating iatrogenic instability can be circumvented, and the risk of dural injury is also reduced. Material and Methods: We report a case of eight year boy complaining of low back pain from six months. He was diagnosed with osteoid osteoma of lumbar spine. Lesion was very close to facet joint and dura. It was excised en bloc using ultrasonic bone scalpel without any violation of facet joint. Results: Patient was immediately pain-free of night pain post procedure. There was no instability or scoliosis at one year follow-up. Conclusion: Children presenting with long term low back pain diagnosis of osteoid osteoma should be kept in mind. Ultrasonic bone scalpel aids in precise surgical excision of Osteoid osteoma. Added advantages are minimal blood loss and less chances of iatrogenic dural tear.

1248

P669: Challenges in the Management of Aneurysmal Bone Cysts of the Spine: A Proposed Treatment Strategy

Aju Bosco ¹ and Nalli Ramanathan Uvaraj ¹

¹ Madras Medical College, Orthopedic Spine Surgery Unit, Chennai, India

Introduction: Aneurysmal Bone Cyst (ABC) is a rare non-neoplastic expansile osteolytic lesion of the spine which is highly vascular and locally destructive. Management of aneurysmal bone cysts of spine is a challenging entity, as it involves resection and reconstruction of the involved functional spinal unit. There may be a need to stabilize the spine to address the instability that results after resection. Various treatment modalities described in literature have been used singly or in combination. Yet they are notorious to recur (recurrence rate of 4% to 44%). We have described an effective strategy for the management of aneurysmal bone cysts of the spine and have analyzed the midterm clinical and functional outcomes of the same. Materials and Methods: Our experience in the management of six patients with aneurysmal bone cyst of the spine [Thoracic (n = 4) and Lumbar (n = 2) spine] is presented. All six patients presented with back pain and neurological deficit. Patients were managed according to the following protocol. After a detailed radiological evaluation to determine the extent of the tumor, the appropriate treatment plan was devised based on Enneking staging. Selective arterial embolization of the feeding vessel was done 48 hours prior to surgery, to reduce the vascularity of the lesion. Posterior stabilization, followed by en bloc resection with anterior column reconstruction using mesh cage was done through a transthoracic approach for dorsal spine lesions. The lumbar lesions were managed with posterior stabilization and intralesional curettage through transforaminal approach. Outcomes were analysed using VAS (Visual Analogue Scale) scores for pain, SF-12 scores, neurological improvement and radiological evaluation of recurrence. Results: The mean age at presentation was 21.5 ± 5.3 years. Back pain (66.7%) and neurological deficit (33.3%) were the most common presenting symptoms. The mean operating time and intraoperative blood loss were 245 ± 23.4 min and 770 ± 54 mL, respectively. Both patients who presented with neurological deficit showed complete recovery at final follow-up. There was no neurological worsening in any patient. Five patients had good recovery of symptoms with no recurrence of the lesion at a mean follow-up of 39.2 ± 6.7 months. One patient with lumbar spine lesion had recurrence at one year follow-up, who was treated with reexploration, complete excision of the lesion and adjuvant therapy with Denosumab. There were no intra-operative or post-operative complications. Conclusion: Before embarking on surgical management, meticulous assessment of the extent of tumor by detailed radiological evaluation is essential in deciding the optimal surgical approach to ensure complete disease clearance. Pre-operative embolization facilitates complete removal of the tumor by reducing tumor vascularity. Complete removal of the lesion based on Enneking staging, along with reconstruction of the spine through spinal stabilization, through an all-posterior or separate anterior and posterior approaches, where appropriate is essential to prevent recurrence. Adjuvant therapy with denosumab helps prevent recurrence. Our management strategy is effective as evidenced by the good midterm clinical outcomes at a mean follow-up of 39.2 ± 6.7 months.

Keywords

aneurysmal bone cyst, treatment, surgery, recurrence

1249

P670: Adaptation and Validation of the Spine Oncology Study Group Outcomes Questionnaire (SOSGOQ) in Italian Language

Giovanni Barbanti Bròdano ¹ , Eleonora Pesce ¹ , Cristiana Griffoni ¹ , Martina Piccinni Leopardi ² , Giuseppe Tedesco ¹ , Loredana Mavilla ² , and Alessandro Gasbarrini ¹

¹ IRCCS Istituto Ortopedico Rizzoli, Oncological and Degenerative Spine Surgery, Bologna, Italy

² IRCCS Istituto Ortopedico Rizzoli, Clinical Trial Centre, Bologna, Italy

Introduction: The population of patients with advanced stages of cancer, including metastatic spinal disease, is growing because of better treatment options allowing a longer control of the disease. The main goal of the treatments for these patients is to improve or maintain their health-related quality of life (HRQOL). Therefore it is important to have efficient instruments to assess patient- reported HRQOL in order to optimize the care treatments. A spine oncology-specific outcome measure has been developed by the Spine Oncology Study Group (Street et al. Spine 2010; 35: 1377- 1386) and validated through international studies. As an Italian version of SOSGOQ does not exist yet, we proposed to translate and validate the questionnaire in Italian language, in order to use this specific instrument to evaluate HRQOL in patients with vertebral metastases in our referral center for spinal tumors.Material and Methods: The cross-cultural adaptation of the questionnaire was performed according to the guidelines proposed by Beaton and co-workers (Spine 2000; 25: 3186 –3191). In the first step two bilingual translator of Italian mother tongue performed two independent forward translations of the questionnaire. In the second step the two translations from English into Italian (T1 and T2) were revised by two reviewers and the two translators. The working group produced a common version, named T1&2, with the consent of all the members.In the third step two translators of English mother tongue performed their independent back translations into the original language, working on the T1&2 version of the questionnaire and totally blind to the original text. In the fourth step an expert committee formed by all the translators, the two reviewers, a clinical researcher and another spine surgeon compared the two versions obtained by the native English translators starting from the Italian version T1&2 and unanimously the Committee agreed to define the T1&2 version as a valid translation of the SOSGOQ questionnaire in Italian language. After this process, an observational prospective study has been designed and submitted to the local Ethics Committee in order to validate the efficacy of SOSGOQ in Italian language. In this study SOSGOQ is compared to SF-36, a generic validated questionnaire to assess the health-related quality of life. A sample size of 140 patients has been considered sufficient to evaluate the validity of the instrument and perform statistical analysis.Results: Starting from January 2020 the SOSGOQ and SF-36 questionnaires were auto-administered to 86 patients affected by spinal metastases. All patients provided written informed consent for study participation. We observed that patients had no problem to complete SOSGOQ and only items 9 and 10 concerning bowel and bladder functions required some explanations for the patient to understand their correct meaning. Conclusion: The statistical analysis of the results obtained at the end of the study will allow to accept the Italian version of SOSGOQ as a specific and efficient tool to measure HRQOL in Italian-speaking patients affected by spinal metastases. We would expect to have complete results available by the time of the conference.

1289

P671: Carbon-Fiber-Reinforced Peek Fixation System in the Treatment of Spine Tumours

riccardo ghermandi ¹ , Marco Girolami ¹ , Maria Concetta Meluzio ² , Giuseppe Tedesco ¹ , Giovanni Barbanti Bròdano ¹ , Stefano Bandiera ¹ , Silvia Terzi ¹ , Gisberto Evangelisti ¹ , valerio pipola ¹ , and Alessandro Gasbarrini ¹

¹ IRCCS Istituto Ortopedico Rizzoli, Oncological and Degenerative Spine Surgery, Bologna, Italy

² Policlinico Gemelli, Roma, Italy

Introduction: Combination of surgery and radiotherapy is becoming more frequent for the treatment of bone tumors of the spine. Metallic hardware interfere with postoperative radiotherapy due to the artifacts on imaging and due to scattering effects. The risk of over-irradiation of neighbouring structures limits the dose delivered making treatment less effective. Composite materials such as carbon-fiber-reinforced (CFR) polyethil–ether–ether–ketone (PEEK) have been used since many years for interbody and body replacement cages. These cages are radiolucent, allowing easy planning CT scan, early detection of local recurrence and very useful to avoid any scattering effect during radiotherapy. Material and Methods: We retrospective evaluate the first 99 consecutive patients affected by primary or metastatic spinal tumor that were treated using a composite CFR-PEEK fixation system. During follow-up period (6-48 months) local control, overall survival and complications were collected and classified accordingly. Results: There were 52 male and 47 female, mean age 58 years (range 18-78). 65 cases were primary tumour and 34 were metastases. A separation surgery has been performed in 54 cases, a gross total excision in 28 cases and en-bloc resection in 17 cases. Weight-bearing was encouraged in the immediate post-operative course for all the patients without orthosis. Conclusion: Thanks to radiolucency CFR-PEEK stabilization devices are more suitable in patients eligible for radiotherapy: the absence of image artifacts together with significantly less dose perturbation improve the treatment accuracy. Moreover, the radiolucency is useful in the follow-up of patients allowing early detection of local recurrence. The advantage of CFR/PEEK composite implants and radiation therapy in terms of overall survival needs to be prospectively defined with larger patient series and longer follow-up.

1309

P672: A Large Prospective Clinical Study of Primary Intraspinal Tumor Patients in China

Nicholas Van Halm-Lutterodt ^1,2 , Ziyang Ye ^3,4 , Wei-Cheng Chen ⁵ , Wei-Hsun Huang ² , Mohamed Kamal Mesregah ¹ , Brandon Yoshida ¹ , Andrew Mecum ⁶ , Krishna Mandalia ¹ , Mercy Bartels-Mensah ⁷ , Wenxin Lei ⁸ , Yu Wang ² , and Yulun Xu ²

¹ Keck Medical Center of University of Southern California (USC), Department of Orthopaedics and Neurosurgery, Los Angeles, USA

² Beijing Tiantan Hospital, Department of Neurosurgery, Beijing, China

³ University of Chicago Graham School of Continuing Liberal and Professional Studies, University of Chicago, Department of Business and Analytics, Chicago, USA

⁴ Wake Forest University, Department of Mathematics and Statistics, Winston-Salem, USA

⁵ Beijing Tongren Hospital, Department of Clinical Sciences, Beijing, China

⁶ Emory University, Department of Psychology, Atlanta, USA

⁷ University of Debrecen, Department of Clinical Sciences, Debrecen, Hungary

⁸ Melbourne University, Department of Mental Health Nursing, Parkville, Australia

Introduction: The clinical and perioperative outcomes of intraspinal tumor patients have been well documented in the spine literature. However, large prospective studies of these outcomes from comparison between dura-based anatomical locations of these primary spinal cord tumors (SCT) are highly lacking. Our goal was to determine baseline and 2-year postoperative differences in neurological and patient-related outcomes (PROs) between the dura-based groups to highlight patient-physician expectations, inform SCT patients of the potential outcomes of microsurgery and guide perioperative decision-making in the practice field. Materials and Methods: Following approval by the institutional review board (IRB) of Beijing Tiantan Hospital-Affiliated Capital Medical University in Beijing, a prospective clinical study of 359 adult (≥18 years) primary spinal cord tumor (SCT) patients who underwent surgical treatment with no prior primary therapy from January 2017 to December 2017 were evaluated. The patients were then trichotomized into intramedullary (IM-SCT), intradural extramedullary (IDEM-SCT), and extradural (ED-SCT) groups, respectively. Perioperative clinical, neurological syndromes (pain, radiculopathy, and myelopathy), and PROs were compared between the studied patient groups at the specified timelines. Key primary outcomes comprised of demographics, tumor-related findings as well as W.H.O. classification of SCTs between the dura-based groups. Secondary outcomes included perioperative findings with patient self-reported measures that included: pain intensity’s visual analogue scale (VAS), Neck Disability or Oswestry Disability Indices (NDI or ODI). Functional measures included: McCormick’s classification and the RAND-36 (SF-36) health-related quality of life (HRQoL) questionnaire. The univariate outcomes between the dura-based groups were carried out by analysis of variance (ANOVA), chi-square and Kruskal Wallis equality-of-population rank tests. General linear model (GLM) was employed for multivariate analyses with baseline comorbid status, Charlson Comorbidity Index (CCI), and perioperative multivitamin intake treated as covariates. All analyses were two-tailed with statistical significance considered when P < .05. Results: Of the 359 patients, 27.9% (n = 100), 65.7% (n = 236), and 6.4% (n = 23) were IM-SCTs, IDEM-SCTs, and ED-SCTs, respectively. The overall average age of patients was 45.1years with a female incidence of 52.9%. Rates of smoking and CCI > 3 were significantly higher in IM-SCT and ED-SCT groups, (P < .05). The highest rate of malignancy (7%) (W.H.O. III) was observed in IM-SCT group. Significant intraoperative somatosensory evoked potential (SSEP) and magnetic-motor evoked potential (mMEP) changes, duration of surgical procedure, average HLoS and 2-year postoperative PROs of disability, McCormick classification and HRQoL scores showed more inferior outcomes in the IM-SCT and IDEM-SCT patient groups. Among all the groups, postoperative pain and myelopathy rates significantly declined from observed baseline rates, but exceedingly minimal improvement rates at 10.1% and 36.2% were observed for radiculopathy in IM-SCTs and IDEM-SCTs, respectively (P < .05). Conclusion: This study corroborates the evidence that microsurgical management of SCT patients results in significant improvements in neurological and overall patient outcomes. All groups improved by ≥90% for overall pain and radicular pain incidences postoperatively. Myelopathy improvement rates were higher in the IM-SCT and IDEM-SCT groups. Rates of residual and/or newly accrued neurosensory deficits (particularly, paresthesia) resonated higher in IM-SCT (89.9%) and IDEM-SCT (63.8%) groups at 2-year postoperative. At 2-year postoperative, ≥80% of all patients were fully satisfied.

1322

P673: Lumbar Vertebral Hemangioma Causing Neurogenic Claudication: Literature Review

Matias Nahuelpan Sanhueza ¹ , Diego Contreras ¹ , Cristian Ricardo Correa Valencia ¹ , Marcelo Droguett Mallea ¹ , and Rodolfo Lopez Allendes ¹

¹ Hospital Regional HHHA/UFRO, Traumatologia - Ortopedia, Temuco, Chile

Introduction: Lumbar vertebral hemangioma causing neurogenic claudication is a rare condition of which few cases have been described in the literature, and a low percentage of these appear in the lumbar spine. The purpose of our presentation is to describe a new case of this entity, to deepen understanding of the clinical and imaging findings of this condition as well as its treatment. Material and Methods: Retrospective study of a clinical case that arrived for consultation presenting neurogenic claudication; Clinical evaluation, physical examination, imaging studies. Results: We evaluated: history, clinical picture, age, gender, type of images requested and their results, treatment undertaken and time of evolution of the symptoms. A literature review was made of this condition, comparing what has been published with our experience. Conclusion: Lumbar vertebral hemangioma causing neurogenic claudication is a rare benign tumor l that can produce backache and neurological compression. The patient consults due to the appearance of neurological disorders secondary to compression phenomena, MRI is the test of choice for the evaluation of this pathology. Recovery from the symptoms occurs in most cases after surgical decompression. Surgery is a safe and effective treatment. with a good prognosis alone or associated with another intervention.

1326

P674: Paraganglioma of the Cauda Equina: A Case Report

Yassine Gdoura ¹

¹ Habib Bourguiba Hospital, Neurosurgery, Sfax, Tunisia

Introduction: Paraganglioma of the cauda equina is a rare tumor. It is a slowly growing neuroendocrine type tumor classified as grade I according to the WHO classification. The treatment is surgical. We report a case of cauda equina paraganglioma collected in our department with a review of the literature. Material and Methods: It’s a case report. Results: A 74-year-old patient, with no previous history, was admitted for bilateral lumbar pain that had progressed for 1 year, without gait disturbances, sphincter disorders or motor deficit. He had no osteotendinous reflexes in his lower limbs. Lumbar MRI revealed an intra-ductal lesion suggesting a lumbar neuroma next to L3. The dural opening revealed an encapsulated and vascularized lesion of the filum terminal which we remove “en bloc” while retaining the carrier root. Histological examination confirmed the diagnosis of a paraganglioma. The patient evolved well postoperatively. Conclusion: Paraganglioma is a benign tumor for which the preoperative diagnosis is difficult. The treatment is surgical aimed at complete excision and preservation of the carrier root to prevent possible recurrence and ensure a better functional prognosis.

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P675: Primary Malignant Lymphoma in a Spinal Cord Presenting as an Epidural Mass: Report of Two Cases

Ines Cherif ¹ , Fatma Kolsi ¹ , Omar Hattab ¹ , Firas Jarraya ¹ , Brahim Kammoun ¹ , and Boudawara Mohamed Zaher ¹

¹ Habib Bourguiba University Hospital, department of neurosurgery, Sfax, Tunisia

Introduction: Malignant lymphoma can involve the central nervous system either primarily or by secondary spread, which tends to occur late in the disease as part of widespread dissemination. Lymphoma presenting as primary tumors of the spinal cord are extremely uncommon. Materials and Methods: We report tow cases of primary malignant lymphoma in a spinal cord. Results: The first case was about a 59-year-old-woman who presented with progressive paraparesis over 2 weeks. Magnetic resonance imaging revealed a spinal epidural mass from T2 to D4. We performed a decompressive laminectomy and mass removal. The histopathology was consistent with a small cell lymphoma B. The second patient was a 60-year-old -men who presented with progressive paraparesis and sphincter changes over 2 weeks. Magnetic resonance imaging revealed a spinal epidural mass from T3 to T5. We also performed a decompressive laminectomy and mass removal. The histopathology was consistent with a large cell lymphoma B. Both patients were addressed to chemotherapy and radiotherapy. Conclusion: Primary central nervous system lymphoma is a rare form of extranodal lymphoma, particularly isolated primary spinal lymphoma. A primary small lymphocytic lymphoma of the spine should be considered in the differential diagnosis of primary spine tumors. Surgical decompression and tumor removal are mandatory to recover neurologic function, if the patient had a neurologic deficit. The combined modality treatment after surgical decompression resulted in improvement of the neurologic symptoms and remission of the lymphoma.

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P676: Intra Medullary Pilocytic Astrocytoma: A Case Report

Ines Cherif ¹ , Fatma Kolsi ¹ , Omar Hattab ¹ , Firas Jarraya ¹ , Brahim Kammoun ¹ , and Boudawara Mohamed Zaher ¹

¹ Habib Bourguiba University Hospital, Department of Neurosurgery, Sfax, Tunisia

Introduction: Pilocytic astrocytoma is the benign form of astrocytomas. It represents a classic tumor of the posterior fossa in children. Its intraspinal localization is much less well known. Patients and Methods: We report a case of intra-medullary pilocytic astrocytoma occurring in an 11-year-old girl. Case Report: An 11-year-old girl presenting gait disorders that had been evolving for 2 months, associated with gestational disorders of both upper limbs and vesico-sphincteric disorders. The examination founded a spastic paraparesis with peripheral brachial diplegia. Medullary MRI revealed an intramedullary lesion ranging from the medullary bulbo junction to D4. Complete excision was performed. Histological examination confirmed the diagnosis of pilocytic astrocytoma. Conclusion: Intramedullary astrocytomas are rare tumors. The clinical symptomatology is nonspecific. Medullary MRI is quite evocative, showing an iso or slightly hypo-intense lesion in T1, hyper-intense in T2 and often associated with cysts. The enhancement after injection of GADO is smaller and more eccentric than ependymoma. The most complete surgical excision possible is necessary to ensure a good evolution of the patients.

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P677: Validation of a Novel Risk Calculator for the Outcome After Surgery for Metastatic Spine Disease

Christian Weger ¹ , Sophia Roser ¹ , Richard Ferch ¹ , Rob Kuru ¹ , and Mitchell Hansen ¹

¹ John Hunter Hospital, Newcastle, Australia

Introduction: Contemporary care of symptomatic metastatic spine disease (MSD) is multidisciplinary and is continuously improving patient’s quality of life with disease and survival rates. Scoring systems and models developed in the past are lacking adaptive mechanisms for current data. Hence the clinical decision regarding the extend of complexity of the operation can be challenging. The aim of this study was to externally validate an online risk calculator with our dataset of vertebrectomy patients. Material and Methods: The novel risk calculator of the Global Spine Tumour Study Group (GSTSG risk calculator; www.spinemet.com) for the risk of death at 3,6,12 and 24 months, has been applied retrospectively on our database of patients with MSD. Vertebrectomies with anterior reconstruction have been performed between 2006 and 2016 if the estimated life expectancy was greater than 3 months. Medical records were reviewed and data was obtained regarding primary malignancy, presenting symptoms, pre-operative chemotherapy and radiotherapy to the spine, type of analgesia, ASA, metastasis to lung, liver and viscera as well as extraspinal bone metastasis. Results: The GSTSG risk calculator was applied on 104 patients and the risk of death at 3, 6, 12 and 24 months has been calculated. The dataset was divided in to two groups; Group A survival under 24 months (60 patients, mean age 61.98) and Group B survival over 24 months (44 patients, mean age 60.29). In Group A the mean survival was 6.8 months, the calculated risk of death at 6 months was 33.13%, and 64.83% at 24 months. Group B contains had a mean survival of 66.61 months. The mean calculated risk of death at 24 months in this group was 50.83%. A subgroup of 13 patients (mean age 61.59) with a survival under 3 months had mean predicted risk of death of 23.03% at 3 months and 75.29% at 24 months. Conclusion: Vertebrectomy is a safe and effective means of providing circumferential neural decompression and stabilization with an acceptable complication rate in patients with MSD, irrespective of age. Recently developed predictive scoring systems such as the GSTSG risk calculator can be useful to tailor operative interventions for each patient individually in order to improve functional outcome and reduce complications.

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P678: Composite PEEK/Carbon Fiber Implants: Application in Primitive and Metastatic Spinal Surgery

Riccardo Cecchinato ¹ , Matteo Saladini ¹ , Andrea Redaelli ¹ , Marco Damilano ¹ , Daniele Vanni ¹ , Francesco Langella ¹ , Giuseppe Peretti ^1,2 , and Stefano Boriani ¹

¹ IRCCS Istituto Ortopedico Galeazzi, Milano, Italy

² University of Milan, Department of Biomedical Sciences for Health, Milano, Italy

Introduction: Radiotherapy (RT) is often applied as an adjuvant therapy in spinal tumors treatment. Metallic implants can decrease the quality of RT planning and execution, as it is known that the backscattering effect they produce can limit RT accuracy and that their presence can be associated with unwanted dose increase. PEEK/carbon fiber (CF) implants are designed to reduce these problems, as their positive effects on postoperative RT are widely demonstrated. In this study we analyzed the use of CF implants in our Division, evaluating their impact and the different modalities of application in the different regions of the spine and in different kind of surgeries. Material and Methods: We retrospectively analyzed our database on oncological spine patients and highlighted all the patients that received a CF implant. Patients demographics, oncological and surgical data, intraoperative and postoperative complications and patients outcomes were collected. Results: Twenty-seven patients received CF implants for primitive (15) or metastatic (12) neoplasms of the spine. 6 patients received an en bloc resection of the tumor, while 21 patients had an intralesional surgery. 4 custom made CF cages were implanted to substitute the removed vertebral body. Most of the surgeries were in the thoracolumbar region (23), but 4 patients received a hybrid construct in the cervicothoracic region. In one case the CF implant was connected to an already existing metallic hardware. Two implant failures (1 rod breakage, 1 connector failure) were observed. Conclusion: CF represent a promising material for spinal implants both in primitive and metastatic spinal surgery. Our analysis shows that the rate of implant failure is low and the adaptability of the system to the spine acceptable, even if custom made cages can still represent a weak point in terms of easiness of implant and connection. Hybrid constructs in the cervicothoracic area with subliminal bands can overcome the limited selection of screw diameters.

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P679: Role of PET Scan in Management of Secondaries of Spine - A Retrospective Multicentric Study

Jitesh Manghwani¹, Harvinder Singh Chhabra¹, Shankar Acharya², Ajoy P Shetty³, and Bhavuk Garg⁴

¹ Indian Spinal Injuries Center, New Delhi, India

² Sir Gangaram Hospital, New Delhi, India

³ Ganga Hospital, Coimbatore, India

⁴ AIIMS, New Delhi, India

Introduction:

• Spine is the third most common site of metastasis after lung and liver

• The most common tumours to metastasize to the spine include breast, prostate, thyroid, lung, and kidneys

• Median survival of patients with spinal metastatic disease is 6 months

• Cord compression is usually seen as a pre terminal event and the median survival at that stage is about 3 months

• MRI is the gold standard and investigation of choice in the work up for spinal metastasis

• Except for scattered case reports, the role of PET-CT in the diagnosis and work up for primary malignancy in spinal metastasis is lacking

Hypothesis: PET-CT scan as an adjunct to MRI improves the outcome by avoiding the need for a vertebral biopsy in some cases, identifying a more feasible site for biopsy in some others and increasing the diagnostic yield of biopsy. Material and Methods: Retrospective study. Sample size: 206 (120+47+25+14)- 4 centre. Inclusion criteria: Patients with Age >40 years with suspected to have spinal metastasis. Exclusion criteria: Patients with Age < 40 years, Presence of markers of multiple myeloma on serum protein electrophoresis (i.e. a positive M spike) before the biopsy, Features of other pathologies like primary hyperparathyroidism or other metabolic disorders before the biopsy, or of spinal infection including tuberculosis like spondylodiscitis, presence of abscess were excluded. Results: As per our series, the most common level of involvement: Thoracic > Lumbar > Thoracolumbar with most common involvement of a single vertebral body. The most common primary was GI tract followed by lungs. The diagnosis prior to suspicion was the same in both the groups with no statistical difference. The patients of MRI group had significantly higher requirement of surgery as compared to those in PET & MRI group. PET was able to detect patients with widespread metastasis limiting life expectancy such that surgery was obviated. Patients of MRI group had significantly higher requirement of vertebral biopsies as compared to patients of PET scan group. PET was able to detect soft tissues from which biopsies could be done more easily. The diagnostic yield was similar in both the groups with no statistical difference. The survival and the prognosis did not differ statistically in the two categories. Medical line of management (radiotherapy, chemotherapy, hormone therapy) did not differ in the two groups. Conclusion: PET scan in patients of suspected metastasis offers the advantage of the possibility of obviating the need for a vertebral biopsy in a significant number of patients in whom biopsy can be done from more feasible soft tissue sites. It also obviates a surgical procedure in a significant number of patients without affecting survival post diagnosis as compared to those undergoing MRI scan alone. PET may thus be a useful complement to MRI in evaluation of spinal metastasis. However a larger study involving a larger number of patients and more centres may be required before advocating it as a gold standard.