E-Posters

Arthroplasty-Cervical

P001 - Long Term Results With Activ C^@ Cervical Total Disc Replacement (CTDR)

Shreya Srinivas¹, Susan Cadman², Michael O Malley³, Lorcan Mcgonagle⁴, Clare Morgan², Ian Shackleford²

¹Department of Spine Surgery, Vancouver General Hospital, Vancouver - Canada ²Department of Orthopaedics, Warrington and Halton NHS Trust, Warrington - United Kingdom ³Department of Orthopaedics, Southern Cross hospital, Invercargill - New Zealand ⁴Department of Trauma and Orthopaedics, Adelaide - Australia

Introduction: Cervical disc replacement (cTDR) is a popular treatment for cervical degenerative disc disease. While some devices have shown promising results in the early and midterm, long term results remain lacking. This study reports on patient outcomes at long term follow up for the Activ C^@ prosthesis. Materials and Methods: Between 2007 and 2009, patients who underwent cTDR for cervical degenerative disc disease at a NHS district general hospital were included. All were assessed preoperatively and at 6, 12, 24 and 105 months after procedure with visual analogue score (VAS) for neck and arm pain severity and frequency, Neck Disability Index questionnaire (NDI) and Centre for Epidemiologic Studies Depression questionnaire (CES-D). We calculated the survival rate of implants (Kaplan- Meir curve) [end point of reoperation at same or adjacent level] and compared patient outcomes (paired t test; MedCalc^@). Results: We had treated 72 patients (25 men, 47 women) with cTDR (61 radiculopathy and 11 myelopathy symptoms) with average age of 52.2 years. We were able to interview 47 patients (65% follow up rate) at long term follow up (average 105 month). VAS (mean) for neck pain improved from 6 to 2 at 12 and 24 months and comparable at 105 months (VAS =3) [p < 0.006] . Arm pain (mean VAS) showed periodic improvement 7 to 5 (12 months); VAS 4 (24 months) and significantly better at 105 months (VAS = 3) [p < 0.006]. NDIQ (average) improved from 51 to 30 at 12 months, 35 at 24 months and 26 at 105 months (p < 0.0001). CES-D scores improved from 20 to 13 at 12 months, 18 at 24 months and 14 at 105 months (p < 0.0001). In the smaller subgroup that underwent cTDR for myelopathy, 10 patients were followed up to 2 years but only 2 reviewed long term (7 lost to follow up, 1 dead). However, these patients only maintained improvement in arm pain seen at 2 year follow up [VAS (preop: 24 m:105 m) = 6:4:3] and neck pain was worse [VAS (preop: 24 m:105 m) = 6:2:6]. There was deterioration in NDIQ and CESD scores seen in early follow up period, NDIQ (preop: 24 m:105 m) 51: 35: 57 and CES -D (pre, post op 2y, follow up 8y) = 20:18:17. There were no adverse events recorded at the time of procedure. There were no revisions performed at the same level, 3 patients had further adjacent level cTDR(2 at 2 years, 1 at 9 years) and median survival time was 8.62 years (7.22 to 10.05 95% CI). Conclusion: Cervical TDR improves pain and function in patients with cervical degenerative disc disease both in the early and long term. We are able to report a survival time of 8.6 years with the Activ C^@ prosthesis with no revision surgery performed at the same level. However, the long term benefit of cTDR performed for myelopathy is not clear.

P002 - Cervical Disc Arthroplasty: Clinical Outcomes, Heterotopic Ossification And Adjacent Segment Disease At Ten Years Follow-Up

Roberto Assietti¹, Alessandro Versace²

¹Chief of the Department of Neurosurgery, ASST Fatebenefratelli Sacco, Milan - Italy ²Department of Neurosurgery, ASST Fatebenefratelli Sacco, Milan - Italy

Introduction: Cervical disc arthroplasty (CDA) has been shown to be capable of achieving functional outcomes superior of equivalent to ACDF in selected patients. CDA has potential advantages of avoiding the complications after ACDF such as adjacent level degeneration and pseudoarthrosis, on the other hand the problem of CDA is the loss of range of motion by heterotopic ossification (HO), specially in long-term follow-up. Usually patients are young, they have a wide range of motion and tend to require an higher quality of life. Unfortunately, the durability remains largely unknow. We revised our casistic of CDA from 2003 to 2007 with minimum follow-up of 10 years. Material and Methods: A retrospective study included 57 patients underwent CDA with Bryan artificial disc between 2003 and 2007 (monocenter and monosurgeon cases), and who had more than 10 years of follow-up. Mean age 54,5 years (41-71); 28 M, 29 F; 43 patients had single-level surgery and 14 patients had double-level surgery: C2-C3 0 (0%); C3-C4 5 (7,0%); C4-C5 8 (11,3%); C5-C6 35 (49,3%); C6-C7 23 (32,4%). We evaluated clinical results by NDI and VAS at 6 m, 1, 2, 5 and 10 years. Imaging data were performed before and after surgery: we measured heterotopic ossification (HO) at 2 and 10 years: we used McAfee classification. Adjacent segment disease has been checked at 10 years Results: The NDI decreases at each follow-up time point: from 40.7% (22-56%) pre-op to 14.5% (0-60%) 10 years after surgery. VAS was 6.3 (4-9) pre-op and 1.8 (0-8) at 10 years. For what concerns the heterotopic ossification we found it in 17 patients (30%): 5 cases (12%) in single-level treated and in 12 (86%) with double level surgery, at two years. We found: 2 (4%) grade I, 12 (21%) grade II, 2 (4%) grade III and 1 (2%) grade IV. HO was unchanged at the ten years follow-up. Adjacent segment disease was found, at ten years, in 5 patients (10%). Conclusion: We found good clinical outcomes with the NDI decreased from 40.7% pre-op to a 14.5% at the last follow-up, also VAS dropped from 6.3% pre-op to 1.8% at ten years post-op. In total, we recorded 17 cases of HO (30%). Fortunately, in 14 cases it was not a clinical problem since, being class I and II, ossification did not interfere with the movement of the segment. Just 3 patients had a reduction in the ROM due to HO. Moreover new case of HO or worsening of know cases have not been reported at ten yeas follow-up. This could mean that HO is an early phenomenon and does not affect the functionality of disc protesis in long-term period. Adjacent segment disease was found just in 5 cases (10%) at 10 years. This study, although not very large, has the advantages of having a long term follow-up and being monocentric and monosurgeon. From this study emerges that CDA remains effective even at ten years and the most relevant complications develop early, within two years, and they do not tend to progress.

P003 - Medium-Term Outcomes Of Activ-C Artificial Disc Replacement For Symptomatic Single Level Cervical Degenerative Diseases

Yuqiang Wang¹, Yilin Liu¹, Limin Wang¹, Weidong Wang¹, Yang Zhang¹, Min Zhang¹, Hao Yang¹

¹The First Affiliated Hospital of Zhengzhou University, Zhengzhou - China

Introduction: Anterior cervical discectomy and fusion (ACDF) is a conventional and well-accepted surgical procedure as the “gold standard” to treat symptomatic cervical disc disease. However, there is evidence showing that ACDF may result in adjacent segment degeneration. Cervical artificial disc replacement (ADR) has become a progressively popular surgical procedure to substitute ACDF in recent years. The purposes of ADR are to accomplish the same neural decompression as that of conventional fusion surgery and to restore disc height and maintain the motion of joint. However, few clinical studies have specifically aimed to assess the incidence of adjacent segment disease (ASD) after ADR. There are different conclusions about whether replacement in cervical spine will accomplish its primary purposes to improve clinical outcomes and reduce ASDs. This article will present surgical experience and mid-term effect of Activ-C artificial disc replacement. Material and Methods: A retrospective analysis of 34 cases with symptomatic single level cervical degenerative diseases received ADR from January 2012 to December 2013. There were 21 males (mean age 43.7 ± 10.3 years) and 13 females (mean age 45.2 ± 10.1 years). JOA (Japanese Orthopaedic Association), VAS (Visual analogue scale), NDI (Neck disability index), CCI (Cervical curvature index) and ROM (Range of motion) during follow-up were observed. Then all the clinical datas were analyzed. Results: All patients were treated as surgical procedures. Patients were followed up for 38 to 54 months with an average of 40.6 months. Heterotopic ossification was found in 6 cases (the incidence was 17.6%). The bone fusion in the ADR segment occurred on one case. The postoperative scores of the JOA (14.9 ± 0.8) were significantly improved compared with preoperative scores (8.1 ± 0.7) (p < 0.05), while VAS (1.2 ± 0.6) and NDI (31.4 ± 20.3) were decreased compared with preoperative ones (VAS: 7.2 ± 0.5, p < 0.05) (NDI: 51.5 ± 28.4, p < 0.05). CCI was decreased from 14.60 ± 2.94% to 14.03 ± 2.76%). However, there was no significant differences (p > 0.05). What’s more, there were no significant differences between postoperative (45.2° ± 13.5°) and preoperative (47.7° ± 13.4°) ROM (p > 0.05). Conclusion: Correct installation of the Activ-C according to surgical procedures is the guarantee for the surgical effect. There is less damage on the end plate during Activ-C ADR. It is in line with demand of cervical physiological function. Medium-term outcomes of ADR is satisfactory. However, it still needs to guard against heterotopic ossification and spontaneous fusion in this surgery.

P004 - MRI Interferences Of 3 Different Prosthesis For Cervical Arthroplasty

Francisco Ardura¹, Ruben Hernandez-Ramajo², Raul Corredera³, Natalia Caballero³, David Noriega¹

¹Department of Orthopedics, Clinical Hospital. Department of Surgery, School of Medicine, Valladolid - Spain ²Department of Orthopedics, Clinical Hospital, Valladolid - Spain ³Department of Radiology, Clinical Hospital, Valladolid - Spain

Introduction: Cervical disc replacement is not only an alternative to fusion on cervical spine. It can be a better solution in terms of motion preservation, clinical results and restoration of biomechanics of the spine and sagittal alignment. However, there are some failures that need to be diagnosed, and MRI is the main tool, despite it can be affected in several ways during postoperative period. Material and Methods: We conducted a study in which we compared three different cervical disc prosthesis; one made of titanium, and 2 made of Co-Cr alloy. Each prosthesis group included four patients. An MRI was performed at 1 year follow-up. Two blinded independent radiologists following the same protocol analyzed the images using 7 locations on each MRI for evaluation and using the Jarvik scale. Results: Titanium prosthesis group showed better scores in terms of visualization of bone, soft tissues and neural structures than both Co-Cr alloy prosthesis (p < 0.05). Both Co-Cr alloy prosthesis showed similar scores. Differences were statistically significant not only for global score but also in each of the 7 areas analyzed. Inside each group, there were no differences in between patients of same group. Conclusion: Cervical arthroplasty in its different modalities of design and materials can be visualized with standard and dynamic x-rays or CT scan. However, proper evaluation of neural elements and adjacent discs are better visualized by MRI. During patient follow-up, it will be important to be able to evaluate those elements, to detect new segments affection, and even more, when clinical evolution is not satisfactory, or when there is clinical recurrence. Therefore, when choosing the prosthesis to be implanted, we should take in consideration the interference of the prosthesis used with the MRI and the quality of the images that we are going to be able to obtain. This will be very important for follow-up and detection of recurrence or new pathology. Titanium cervical arthroplasty allow a better visualization of neural elements and adjacent discs than Co-Cr alloy ones. The visualization obtained with titanium prosthesis is good in order to detect complications after surgery. We should considered the composition of cervical disc prosthesis when choosing which to implant.

P005 - A Novel Elastomer Cervical Total Disc Replacement Device Results In Biomechanics Similar To The Intact Spine: A Finite Element Study

Ali Kiapour¹, Kingsley R. Chin², Jake Lubinski², Vijay K. Goel¹, Joseph M. Zavatsky²

¹Engineering Center for Orthopaedic Research Excellence (E-CORE), Department of Bioengineering, Toledo, OH - United States ²LESS Institute, Fort Lauderdale, FL - United States

Introduction: Total disc replacement (TDR) is expected to provide a more physiologic alternative to fusion. However, long term clinical data which proves the efficacy of current implant designs is somewhat lacking. There are inconsistencies between in-vivo clinical vs. in-vitro biomechanical data. Several factors may be contributing to these anomalies, one of which is the type of disc, metal on metal vs. a metal on polyethylene disc design, for example. This study investigates the biomechanical effects of the placement of a novel elastomer TDR in the cervical spine and compares it to natural spinal kinematics, using finite element analysis. Methods: An experimentally validated, ligamentous, three-dimensional, finite element model of C3-C7 cervical spine segments was used for this study, Figure 1 (Goel et al., 2009). To simulate the replacement of the FREEFORM cervical TDR, the CAD model of the device was meshed and placed into the disc space of the C4-C5 level following removal of anterior part of the annulus, the entire nucleus, and ALL ligament. The endplates of the TDR were affixed to the adjacent vertebral endplate. Properties of titanium alloy and CarboSil 20 80A silicone rubber were assigned to the endplates and implant’s flexible component, respectively. The intact and instrumented spines were subjected to 75 N compressive follower load, plus 1.5 Nm bending moments in anatomical planes to simulate physiological flexion, extension, left/right bending, and left/right rotation. The range of motion, intradiscal pressure, and facet loads were measured and compared for segments of intact and instrumented spines. Results Section: The kinematic data for index and superior adjacent levels are shown in Figure 1. The disc replacement did not significantly alter normal motion of the index level in flexion and left/right bending motions (<7% increase). The percent change was more in extension and axial rotation; 28% (Ext) and 23% (LR & RR) respectively. The motion at the superior adjacent segment was not affected in any planes of motions, except in extension (13% decrease) following disc replacement. The intra-discal pressure at the adjacent segment remained essentially unchanged following TDR except in extension, where there was a slight increase. There was not a significant change in facet loads following instrumentation. Discussion: The elastomer TDR preserved the natural kinematics of the cervical spine following instrumentation specially in flexion and lateral bending motions. A study by Crawford et al. (IJSS 2012) showed that ProDisc-C increased the ROM of the spine by 11% in flexion and decreased by 30% in lateral bending. Deviation from normal spine kinematics is less substantial with this novel TDR design. Also, the FREEFORM TDR did not alter range of motion, intradiscal pressure, or facet joint stress at the adjacent segment. These biomechanical properties may lower the long-term risk of adjacent segment disc and facet degeneration.

Figure 1.

FREEFOMR Cervical Disc, FE model of C37 spine with disc replaced at C45, Range of motion at and IDP at index and adjacent segments.

P006 - Does The Design Of An Artifical Disc Device Influence The Clinical And Radiological Outcome Of Total Cervical Disc Replacement: A Prospective Comparison Trial With 2 Years Follow-Up

Franziska C. Heider¹, Daniel Sauer¹, Tuna Pehlivanoglu², Andreas Korge¹, Christoph J. Siepe¹, H. Michael Mayer¹, Christoph Mehren¹

¹Schön Schön Clinic Munich Harlaching, Spine Center, D-81 547 Munich, Germany - Germany ²Istanbul Faculty of Medicine, Department of Orthopaedic Surgery and Traumatology, Istanbul - Turkey

Introduction: Since several years, different devices of cervical artificial discs are in increasing clinical use to treat symptomatic cervical degenerative disc disease with or without radiculopathy. Currently, numerous trials regarding short-, mid- and long-term follow-ups (FU) have shown excellent clinical results – independent of the design of the artificial disc devices. However, several trials detected an unexpected, high incidence of heterotopic ossifications (HO) with loss of the prosthesis mobility, already in the short-term FU. To investigate and to avoid the high incidence of HO is the challenge for a longtime successful application of a total cervical disc replacement (cTDR). Aim of this study was to evaluate the influence of a new – spike anchoring mechanism regarding the clinical and radiological results 2 years after surgery, with a focus on the development of HO. Material and Methods: Clinical outcome scores Visual Analogue Scale (VAS), Neck Disability Index (NDI), patient satisfaction rates as well as the complication rate were acquired within the framework of an ongoing prospective non randomized, clinical and radiological trial. Patients were treated with a new generation artificial disc device named ProDisc-C Vivo (DePuy Synthes Spine, Oberdorf, CH). This anchoring of this artificial disc is without a keel and opening of the anterior cortex. X-Rays of the cervical spine in ap and lateral views, as well as with flexion and extension views are carried out to evaluate the mobility / function of the prosthesis. Moreover, the incidence of HO was detected. All these data were measured preoperatively, as well as 1 and 2 years after surgery. For comparison, we referred the new data with a previous patient collective (n = 45, 66 prosthesis, 2 years FU), which was treated with the first generation ProDisc-C, using a keel for anchoring. This collective was treated in the same center, whit the identical including criteria. Results: The cohort consisted of 92 patients with 112 implanted prostheses. 72 patients were available for 2 years FU, resembling a 78.26% FU rate. The overall clinical results revealed a highly significant improvement from baseline VAS and NDI levels at all postoperative FU stages. Patient satisfaction rates remained stable throughout the entire postoperative course, with 90.3% of the patients reporting a “highly satisfactory”, and 6.9% reporting a ‘satisfactory’ outcome. Only 2.8% reporting a ‘unsatisfied’ outcome. The radiographic results showed a significant less incidence of HO with a statistically significant difference to our comparison group. High grade ossifications III° and IV° were detected in only 8.79%. This is a significant reduction in comparison with the keel anchoring prosthesis group (27.3% III° and IV°). Conclusion: The clinical results demonstrate that cTDR is a feasible treatment option resulting in improved clinical outcomes, independent of the design of the prosthesis. The radiological findings might reason that the design of the prosthesis and thereby the implantation technique lead to an enormous influence of the incidence of HO. The primary anchoring of the prosthesis without violating the cortical surface might avoid severe ossifications and seems to influence the functionality and mobility of the artificial disc device positively in the progression of time.

P007 (3381) - Correlation of radiographic parameters to clinical outcomes of transforaminal lumbar interbody fusion vs. Lateral lumbar interbody fusion for degenerative lumbar spondylolisthesis

Joseph Palmer¹, Tim Niedzielak², John Malloy IV³, Michael Stark¹

¹Nova Southeastern University College of Osteopathic Medicine, Fort Lauderdale - United States ²Broward Health Medical Center, Fort Lauderdale - United States ³East Coast Orthopaedics, Pompano Beach - United States

Introduction: Lumbar interbody fusion (LIBF) surgery has become an increasingly more common treatment option for many spinal conditions such as degenerative disk disease and spondylolisthesis. LIBF achieves immediate structural support with high fusion rates and has been proven to be superior to conservative treatment for disabling low back pain. A few common approaches for LIBF include anterior, lateral, and transforaminal, all with the goal of improving sagittal balance while maintaining stability of the lumbar spine. The literature suggests that lateral lumbar interbody fusion (LLIF) is superior to transforaminal lumbar interbody fusion (TLIF) in maintaining segmental lordosis. In our study, we compared LLIF to TLIF in their capacity to improve radiographic measurements and its correlation with clinical outcomes. Method and Materials: Medical records and radiographs from 12 patients who received either a LLIF (n = 6) or TLIF (n = 6) between 2013-2015 at a single surgical center by the senior author were evaluated. Radiologic data included preoperative and 6-months postoperative lumbar films for the measurement of the global sagittal balance (GSB) and segmental lordosis. Clinical outcomes were measured with the visual analogue scale (VAS) for pain, which was given preoperatively and at the final follow-up (mean: 19.25 months). Results: LLIF achieved greater segmental lordosis than the TLIF (6.65 and -1.13 respectively, p < 0.05). Although the TLIF produced segmental kyphosis, the GSB of the lumbar spine was maintained and similar in both cohorts postoperatively (54.58 and 57.03). The VAS pain scale demonstrated significant clinical improvement in both the LLIF cohort (7.5 to 1.3, p < 0.001) and the TLIF cohort (9 to 1.8, p < 0.001), and there was not a significant difference between the overall improvement (6.2 and 7.2 respectively, p = 0.20). Conclusions: In conclusion, our study demonstrated an equally significant clinical improvement in both groups. Radiographic data showed the LLIF cohort had a significantly greater increase in segmental lordosis in comparison to the TLIF group. However, overall GSB was equally maintained in both groups. We believe that preserving GSB in LIBF surgery is integral to achieving optimal clinical outcomes. The TLIF group demonstrates the adjacent vertebrae’s ability to compensate for loss of segmental lordosis. The failure to achieve segmental lordosis in the TLIF cohort should caution the surgeon against the utilization of this procedure in multilevel surgeries. Both TLIF and LLIF when utilized in single-level LIBFs should continue to provide successful outcomes.

Arthroplasty-Lumbar

P008 (2244) - Oblique Lumbar Interbody Fusion: Review Of Technical Aspects, Operative Outcomes And Complications

Jia Xi Julian Li¹, Kevin Phan², Ralph Mobbs²

¹Faculty of Medicine, University of New South Wales, Kensington - Australia ²NeuroSpine Surgery Research Group, Randwick - Australia

Introduction: Anterior lumbar interbody fusion (ALIF) and lateral lumbar interbody fusion (LLIF) are commonly used approaches for lumbar spine fusion surgery, each with their own unique advantages and disadvantages. ALIF requires mobilization of the great vessels and peritoneum, and dissection of the psoas muscle in the LLIF technique is associated with postoperative neurologic complications in the proximal lower limb. The anterior-to-psoas (ATP) or oblique lumbar interbody fusion (OLIF) technique is the proposed solution to accessing the L1-L5 levels without the issues encountered with ALIF and LLIF. Currently, there is a paucity of high quality clinical studies detailing the outcomes and complications of OLIF. This review aims to synthesize the technical nuances, operative outcomes and complications achieved thus far in the current literature to gauge the value of OLIF surgery and direct future research. Material and Methods: A systematic search of the literature was performed according to PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. All case reports, cases series and clinical studies were included. Data collected included operative time, blood loss, postoperative hospital stay, and complications, which were then pooled together. Results: From the 16 studies selected, the mean blood loss was 109.9 mL, average operating time was 95.2 minutes, and mean postoperative hospital stay was 6.3 days. Fusion was achieved in 93% of levels operated. Incidence of intraoperative and postoperative complications was 1.5% and 9.9%, respectively. Transient thigh pain and/or numbness and hip flexion weakness occurred in 3.0% and 1.2% of patients, respectively. Conclusion: Early results on the ATP/OLIF technique are promising and warrant further investigation. Future research with well-designed prospective randomized studies is recommended to measure the outcomes of and provide high-level evidence on the potential advantages of OLIF over ALIF and LLIF techniques.

Basic Science

P009 - Human Osteochondral Explant Model – Ex Vivo – For Evaluation Of “Disease Modifying Osteoarthritis Drugs” (DMOAD)

Cordula Netzer¹, Stefan Schaeren¹, Jeroen Geurts¹

¹Department of Spine Surgery, University Hospital, Basel - Switzerland

Introduction: Elevated remodelling of subchondral bone and marrow tissues has been firmly established as diagnostic and prognostic radiological imaging marker for human osteoarthritis. While these tissues are considered as promising targets for disease-modifying OA drugs, the development of novel treatment approaches is complicated by the lack of knowledge whether similar tissue changes occur in rodent OA models and poor understanding of joint-specific molecular and cellular pathomechanisms in human OA. Here, we describe the establishment of a human OA explant model to address this crucial niche in translational preclinical OA research. Material and Methods: Osteochondral (knee, spine) and bone (iliac crest) clinical specimens were acquired from patients undergoing total knee arthroplasty (n = 5) or lumbar spine fusion using bone autografts (n = 6). Fresh specimens were immediately cut in equal-sized samples (50-500 mg wet weight) and cultured in 8 mL osteogenic medium for one week. Samples were either left untreated (control) or stimulated with lipopolysaccharide (LPS, 100 ng/mL) in the absence and presence of transforming growth factor-beta inhibitor (SB-505 124, 10 μm). Pro-collagen-I (Col-I), interleukin-6 (IL-6) and monocyte chemoattractant protein 1 (MCP-1) secretion was determined in conditioned medium by ELISA. Tissue viability was assessed using MTT and alkaline phosphatase (ALP) activity staining. Results: Explanted tissues remained viable after one week culture in control and treatment conditions. Osteocytes, subchondral marrow spaces and calcified cartilage stained positive for ALP activity without gross morphological differences between groups. Median basal secretion levels were Col-I (1.3 ng/mg), IL-6 (135 pg/mg) and MCP-1 (26 pg/mg). LPS treatment led to a significant increase of IL-6 (334 pg/mg) and MCP-1 (72 pg/mg), but not Col-I secretion. Interestingly, inhibition of TGF-beta signalling in osteochondral tissues specifically reduced Col-I levels (0.4 ng/mg) compared to controls and LPS-treated samples. LPS-induced IL-6 and MCP-1 levels were slightly reduced (−80 pg/mg, p = 0.01) and increased (+25 pg/mg/p = 0.02) by SB-505 124 treatment, respectively. IL-6 and MCP-1 levels were strongly correlated under basal (r = 0.60) and treatment conditions (r = 0.60). Conclusion: In this study, we provided proof of concept for the first ex vivo explant model of human osteoarthritis. Osteochondral tissue specimens can readily be cultured without loss of tissue viability and mount a robust inflammatory response upon LPS challenge. Treatment with a potential disease-modifying agent (TGF-beta signalling inhibitor) reduced collagen metabolism in bone and marrow and modified cytokine and chemokine expression. The osteochondral explant model might be highly valuable to evaluate disease-modifying OA drugs.

P010 - Phosphotungstic Acid-Enhanced Micro Computed Tomography For Three-Dimensional Visualization And Analysis Of Collagen Distribution In Human Osteochondral Tissues

Cordula Netzer¹, Stefan Schaeren¹, Jeroen Geurts¹

¹Department of Spine Surgery, University Hospital, Basel, Switzerland

Introduction: Histology remains the gold standard in morphometric and pathological analyses of osteochondral tissues in human and experimental bone and joint disease. However, histological tissue processing is laborious, destructive and only provides a two-dimensional image in a single anatomical plane. Micro computed tomography (μCT) enables non-destructive three-dimensional visualization and morphometry of mineralized tissues and, with the aid of contrast agents, soft tissues. In this study, we evaluated phosphotungstic acid-enhanced (PTA) μCT to visualize joint pathology in spine osteoarthritis. Material and Methods: Lumbar facet joint specimens were acquired from six patients (5 female, age range 31-78) undergoing decompression surgery. Fresh osteochondral specimens were immediately fixed in formalin and scanned in a benchtop μCT scanner (65 kV, 153 mA, 25 μm resolution). Subsequently, samples were completely decalcified in 5% formic acid, equilibrated in 70% ethanol and stained up to ten days in 1% PTA (w/v) in 70% ethanol. PTA-stained specimens were scanned at 70 kV, 140 m, 15 μm resolution. Depth-dependent analysis of X-ray attenuation in cartilage tissues was performed using ImageJ. Bone structural parameters of undecalcified and PTA-stained specimens were determined using CT Analyser and methods were compared using correlation and Bland-Altman analysis. Results: The maximal penetration depth of PTA in decalcified facet joint was 5 mm. Bone tissue showed strong and uniformly distributed X-ray attenuation, while mild to moderate and differentially distributed attenuation was observed in articular cartilage and subchondral marrow spaces. Measurements of bone volume (r = 0.90, p = 0.01) and bone surface (r = 0.95, p = 0.004) were strongly correlated between undecalcified and PTA-stained samples. Compared with PTA-stained samples, measurements in undecalcified specimens were consistently higher (∼14%). PTA-enhanced μCT visualization of cartilage tissues enabled the identification of individual chondrocytes and their pericellular microenvironment (chondrons). Owing to loss of collagen lower X-ray attenuation was observed in the middle and deep cartilage layers at the central, but not peripheral, regions of the degenerated facet joint specimens. Conclusion: PTA-enhanced μCT is a low-cost, non-toxic and highly feasible method for ex vivo 3D-visualization of osteochondral pathology in human osteoarthritis. The method enables bone morphometric analysis, as well as collagen distribution in all anatomical planes. Contrast enhanced μCT has several applications in bone and osteoarthritis research including 3D histopathological grading, tissue stratification, and imaging and analysis of aberrant collagen metabolism in osteochondral disease.

P011 - Using Peripheral Blood Cells To Generate Intervertebral Disc-Like Cells

Yong Hai¹, Yueying Li¹, Tie Liu¹

¹Beijing Chao-Yang Hospital Capital Medical University, Beijing - China

Introduction: An attempt to reprogram peripheral blood cells(PBCs) into human induced pluripotent stem cell (hiPSCs) as a new cell source for intervetebral disc repair. Material and Methods: We generated intervertebral disc(IVD)-like cells from human peripheral blood via iPSCs using integration-free method. Peripheral blood cells (PBCs) were either obtained from human blood bank or freshly collected from volunteers. After transforming PBCs into iPSCs, the newly derived iPSCs were further characterized through karyotype analysis, pluripotency gene expression and cell differentiation ability. iPSCs were differentiated through multi-steps including embryoid body (EB) formation, hiPSCs-mesenchymal stem cells (MSCs)-like cells expansion, and transforming growth factor(TGF)-beta1 induction differentiation for 21 days. Cell phenotype was then assessed by morphological and biochemical analysis, as well as expression studies. Results: hiPSC derived from peripheral blood cells were succesfully generated, which were characterized by fluorescent immunostaining of pluripotent markers and teratoma formation in vivo. Flow cytometric analysis showed that MSCs markers CD73 and CD105 were present whereas hematopoietic markers CD34 and CD45 were absent in mono-layer cultured hiPSCs-MSC-like cells. Both Alcian blue and toluidine blue staining of TGF-beta1 induction differentiation pellets showed positive, and further comfirmed by positive immunochemistry of collagen II and X stain. The glycosaminoglycans (GAG) content was significantly increased and the expression levels cell markers of Col2, Col10, Sox9 and Aggrecan were significant higher . Conclusion: This study indicated the PBCs may represent an attractive source to obtain IVD-like cells in a patient-specific and cost-effective approach, although modification of cultural conditions may required to appraoch the more likely phenotype.

P012 - A Novel Injectable Calcium Phosphate-Based Nanocomposite For The Augmentation Of Cannulated Pedicle-Screw Fixation

Haolin Sun¹

¹Peking University First Hospital, Beijing - China

Introduction: Polymethylmethacrylate (PMMA)-augmented cannulated pedicle-screw fixation has been routinely performed for the surgical treatment of lumbar degenerative diseases. Despite its satisfactory clinical outcomes and prevalence, problems and complications associated with high-strength, stiff, and nondegradable PMMA have largely hindered the long-term efficacy and safety of pedicle-screw fixation in osteoporotic patients.This study focused on the biomechanical properties of the calcium phosphate-based nanocomposite (CPN) in the augmentation of cannulated screw and traditional solid screw fixation in comparison with PMMA, which is expected to provide insights and important reference for further clinical applications. Materials and Methods: CPN was composed of calcium phosphate cement (CPC) and a mixture of gelatinized starch and BaSO4 (BS). Its phase compositions were examined by X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR). Meanwhile, the mechanical strength, degradability and injectability of CPN were evaluated in comparison with PMMA or other calcium phosphate-based cements as well as its fluidity and dispersion ability in synthetic composite bone (Sawbones). Augmentation of cannulated and solid screws in Sawbones blocks by PMMA or calcium phosphate-based cements was then evaluated by axial pullout and torsion tests. Besides, histological analysis of the 8-week rat femur-defect model was used to evaluate the osseointegration capability of the CPN in vivo. Result: (1) The compressive strength of the CPN was almost three times that of CPC and CPC-BS, while the compressive modulus of CPN (2.5 GPa) was almost twice that of PMMA (1.31 GPa), clearly suggesting the reinforcing effect of the starch nanonetwork on the mechanical strength of bone cement. (2) The degradation process evaluated by soaking the cements in Tris-HCl indicated that the CPN had higher degradability than CPC. And the measured injectability reached 95% ± 1% when the L: S ratio of the CPN was 0.6 mL/g. (3) The CPN had higher dispersion ability than CPC, while L: S ratios greater than 0.8 and less than 1.6 are suggested for better diffusion of cement to the cancellous bone in augmentation of cannulated pedicle-screw fixation. (4) In the case of cannulated screws, the CPN reached the highest pullout strength of ∼120 N, which was marginally higher than PMMA but significantly higher than CPC-BS or CPC (P < 0.05). In the case of solid screws, pullout strengths of the CPN, CPC, and PMMA were at a similar level (no significant difference). (5) PMMA resulted in the highest and the CPN the second-highest torque values for both cannulated and solid screws. Average results revealed the maximum torque of PMMA and CPN reached 1,400 Nċm and 600 Nċm for cannulated screws and 1,000 Nċm and 750 Nċm for solid screws, respectively. (6) Histological analysis revealed that the boundary of an originally cylindrical CPN sample changed to one with irregular outlines and bone ingrowth was also found along such irregular boundaries after 8 weeks. And a void also formed in the area close to the center of CPN . Conclusion: CPN is a new injectable, biodegradable, implantable nanocomposite, which outperformed conventional CPC in mechanical properties and exhibited better antipullout ability and similar fluidity and dispersion ability compared to clinically used PMMA, suggesting its potential for the augmentation of cannulated pedicle screws.

Keywords: calcium phosphate nanocomposite, pedicle screw, lumbar degenerative disease, osteoporosis

P013 - A Novel Classification And Treatment Algorithm For Vertebral Body Osteonecrosis (Vbon) Based On Existing Evidence

Matteo Formica¹, Luca Cavagnaro¹, Marco Basso¹, Carlo Formica², Lamberto Felli¹, Stefano Divano¹, Andrea Zanirato¹

¹Università degli studi di Genova, DISC, IRCCS Ospedale Policlinico San Martino IST, Genova - Italy ²GSpine4, IRCCS Istituto Ortopedico Galeazzi, Milano - Italy

Introduction: Osteonecrosis is a clinical entity characterized by a pattern of cell death and a complex process of bone resorption and formation. Bone necrosis is largely investigated in literature only for certain anatomic districts, while it is still lacking in other cases. The evidence of vertebral body osteonecrosis (VBON) is confused and fragmented. The aim of this study is to propose a unique classification and treatment algorithm for VBON based on the most recent literature. Material and Methods: A systematic review of the available English literature about VBON was performed searching in Pubmed, Embase, Medline, Google Scholar, Cochrane Central Register of Controlled Trials (CENTRAL) and CINAHL databases through various combinations of the following keywords: vertebral body osteonecrosis, Kümmell’s disease, intravertebral vacuum cleft, diagnosis, treatment, outcomes. The PRISMA 2009 checklist was completed. Most relevant data were processed for classification and treatment algorithm drafting. Results: At the end of the review process, 81 articles were included in our final manuscript. Three main topics about VBON were identified: 1) pathophysiology and risk factors, 2) diagnosis ad 3) treatment. 45 studies were included in the first group, 52 papers argued about VBON diagnosis and 38 manuscripts illustrated treatment options. We therefore classified VBON in 4 different stages together with a specific treatment algorithm. Conclusion: The literature about VBON is limited and mainly focused on post-traumatic cases with an overlap with non-union and pseudoarthrosis. In this heterogeneous and frequently confused panorama we worked through current literature to deduce a clear and useful classification of this common and often misdiagnosed pathology. The aim of the proposed classification, according to relevant imaging findings and sagittal biomechanical parameters, is to distinguish vertebral body osteonecrosis from simple fractures and to propose a reasoned therapeutic algorithm for different stages of the disease.

P014 - Avoiding The Esophageal Branches Of The Recurrent Laryngeal Nerve During Retractor Placement: Precluding Postoperative Dysphagia During Anterior Approaches To The Cervical Spine

Christian Fisahn¹, Joe Iwanaga², Cameron Schmidt¹, Jens Chapman¹, Rod Oskouian¹, R. Shane Tubbs²

¹Swedish Neuroscience Institute, Swedish Medical Center, Seattle - United States ²Seattle Science Foundation, Seattle - United States

Introduction: Postoperative dysphagia is a significant complication following anterior approaches to the cervical spine. However, the etiology of this complication is poorly understood. Herein, we studied the esophageal branches of the recurrent laryngeal nerves to improve understanding of their anatomy and potential involvement in dysphagia. Material and Methods: Ten fresh frozen cadaveric human specimens were dissected (twenty sides). All specimens were adults with no evidence of prior surgery of the anterior neck. The recurrent laryngeal nerves were identified under a surgical microscope and observations and measurements of their esophageal branches made. Results: For each recurrent laryngeal nerve, 5-7 (mean 6.2) esophageal branches were identified. These branches ranged from 0.8 to 2.1 cm (mean 1.5 cm) in length and 0.5 to 2 mm (mean 1 mm) in diameter. They arose from the recurrent laryngeal nerves between vertebral levels T1 and C6. They all traveled to the anterior aspect of the esophagus. No statistical differences were seen between left and right sides or between sexes. Conclusion: The esophageal branches of the recurrent laryngeal nerve have been poorly described and could contribute to complications such as swallowing dysfunction following anterior cervical discectomy and fusion procedures. Therefore, a better understanding of their anatomy is important for spine surgeons. Our study revealed that these branches are always present and can be avoided by retracting the esophagus laterally, thereby minimizing contact with its anterior surface.

P015 - Lateral Displacement Of The Anterior Longitudinal Ligament In Diffuse Idiopathic Skeletal Hyperostosis

Jonneke Kuperus¹, Esther Smit¹, Behdad Pouran¹, Robbert van Hamersvelt², Marijn van Stralen³, Peter Seevinck³, Stan Buckens², Ronald Bleys⁴, Cumhur Oner¹, Pim de Jong⁴, Jorrit-Jan Verlaan¹

¹Department of Orthopedics, University Medical Center, Utrecht - Netherlands ²Department of Radiology, University Medical Center, Utrecht - Netherlands ³Image Science Institute, Utrecht - Netherlands ⁴Department of Anatomy, University Medical Center, Utrecht - Netherlands

Introduction: Diffuse idiopathic skeletal hyperostosis (DISH) is characterized by bridging hyperostosis of the anterolateral thoracic spine. Although the pathogenesis remains unclear, it is suggested by previous authors that ossification of the anterior longitudinal ligament (ALL) is the onset of this condition. This study was designed to test this hypothesis by evaluating the spatial relation of the new bone formation in DISH with the ALL using both anatomical and radiological imaging techniques. Materials and Methods: Four human cadaveric spines with DISH based on fluoroscopy were selected from the anatomy department of our institution. A spectral CT scan was obtained for all specimens. Subsequently the spines were macroscopically inspected, embedded in carboxymethylcellulose and placed in the cryomicrotome to freeze overnight (-25°C). Sectioning was performed with a slice thickness of 25 micrometers in the axial direction. Every 125 micrometers a digital photograph was taken and every 500 micrometers a section slice was collected on tape. The cryomicrotome images were stacked using in-house build software and were registered to the CT images. The ALL was segmented by hand at the level of the intervertebral disc and at three levels per vertebral body using the cryomicrotome photographs together with the section slices on tape if necessary. The segmented ALL was projected on the CT scan for interpretation of the spatial relation of the ALL and the new bone formation. Results: The four cadaveric spines all had multiple bone bridges with the ALL still clearly distinguishable during the macroscopic inspection. At certain areas the new bone formation appeared to overlay the ALL. The ALL was segmented on the photographs without many difficulties and was present at every level. At the levels without new bone formed the ALL was located centrally anterior of the spine. At the locations where the new bone formation was abundant, the ALL appeared shifted to the contralateral side (mostly left). Conclusion: The presence of the ALL in all four thoracic spines indicates that ossification of the ALL is most likely not the main origin of this condition. The displacement of the ALL to the contralateral side further supports an independent relation between the new bone and the ALL. Our results are in contrast to the currently accepted hypothesis that DISH starts as ectopic bone formation within the ALL.

P016 - The Correlation Of 9.4 T Mri Nucleus Pulposus/Annulus Fibrosus Distinction With Biochemical Markers Of Intervertebral Disc Degeneration

Chris Daly¹, Idrees Sher¹, Peter Ghosh², Tanya Badal³, Ronald Shimmon³, Graham Jenkin⁴, David Oehme⁵, Ronil Chandra⁶, Tony Goldschlager¹

¹Department of Surgery, Monash Medical Centre, Melbourne - Australia ²Proteobioactives, Sydney - Australia ³Chemical Technology Unit, Faculty of Science, Sydney - Australia ⁴The Ritchie Centre, Hudson Institute of Medical Research, Monash University, Melbourne - Australia ⁵Department of Neurosurgery, St Vincent’s Hospital, Melbourne - Australia ⁶Monash Department of Radiology, Monash Medical Centre, Clayton, Victoria 3168, Australia, Melbourne - Australia

Introduction: The 9.4 T MRI is an advanced preclinical imaging system that provides superior resolution of anatomical and morphological detail. Our group has previously described the development and application of a 9.4 T MRI nucleus pulposus(NP)/annulus fibrosus(AF) distinction score and the correlation of this simplified scoring system with 3 T and 9.4 T MRI Pfirrmann grades. We describe the correlation of the simplified NP/AF distinction score with biochemical measures of intervertebral disc degeneration. Material and Methods: Eighteen adult ewes underwent surgical lumbar intervertebral disc injury via a lateral retroperitoneal approach. Disc injury was performed at two levels with the adjacent non-injured levels serving as controls. Non-operated lumbar discs served as normal controls. Necropsies were performed at six months. Lumbar spines underwent 9.4 T MRI axial imaging. Four observers graded the images using the NP/AF distinction score. Spinal columns were dissected, individual discs sectioned, subdivision of the discs into regional segments performed and NP tissues were analysed biochemically for their proteoglycan (as sulphated-glycosaminoglycans), collagen (as hydroxyproline) and DNA content. Statistical analysis was performed with SPSS statistical package consisting of Kappa scores for inter-observer reliability, Pearson correlation co-efficients and simple linear regression. Results: The 9.4 T NP/AF distinction score demonstrated good inter-observer reliability with a kappa score of 0.94. A moderately strong correlation between NP/AF distinction score and collagen was observed with a Pearson correlation co-efficient of 0.719 and R² of 0.517 (both p < 0.001). As expected, there was a negative correlation between NP/AF distinction and nucleus pulposus proteoglycan content with a Pearson correlation co-efficient of -0.545 and R² of 0.297 (both p < 0.001). There was no significant correlation with nucleus pulposus DNA with a Pearson Correlation score of -0.249 (p = 0.170) and R² of 0.62 (p = 0.170). Conclusion: The NP/AF distinction score is a simple system for classifying intervertebral disc degeneration on 9.4 T MRI that demonstrates high degree of inter-observer reliability. This study demonstrated a moderately strong correlation of NP/AF distinction score with NP collagen content and a weaker negative correlation with proteoglycan content. Increased NP collagen content is a well-described feature of intervertebral disc degeneration and typically occurs in tandem with reduced NP proteoglycan content. The advance in resolution afforded by the 9.4 T MRI affords the ability to detect subtle changes in intervertebral disc morphology reflective of underlying degenerative and biochemical changes. The strength of correlation observed between this simple radiological classification system and biochemical markers of intervertebral disc degeneration is suggestive of the potential of the 9.4 T MRI in the investigation and classification of disc degeneration in the future.

P017 - Vertebral Fracture In Osteoporotic Patients Presenting With Hypovitaminosis D - Significance & Experience In Bangladesh

M. Asraf Ul Matin Sagor¹

¹Junior Consultant, Orthosurgery, Shahidnagar Trauma Center, Daudkandi, Comilla - Bangladesh

Introduction: Hypovitaminosis D is widespread and is re-emerging as a major health problem globally leading to bone pain, muscle weakness, increased risk of osteoporosis, falls and fractures. Hypovitaminosis D remain in two forms as deficiency (Serum 25 OHD level < 10 ngm/ml) and insufficiency (serum Vitamin D3 10-30 ng/ml). Causes of osteoporosis (OP) are multifactorial, vitamin D insufficiency can be an important etiological factor in elderly. Materials and Methods: A total number of 468 osteoporotic patients with vertebral compression fracture were included in this study. Patient with osteomalacia was excluded considering clinical and radiological criteria. OP was assessed by bone mineral density (BMD) estimation using GE Healthcare Lunar Prodigy densitometer. After confirmation of OP and vertebral compression fracture by X-ray, serum Vitamin D3 level was measured using Enzyme Linked Fluorescent Assay. Results: Majority patients in age group 40-60 years which was 260(55.6%) followed by 60-80 years of age which was 185 (39.5%) and 16 (3.4%) cases were above 80 years. Female vs male was 449 (95.9%) vs 19 (4.1%) respectively. Hypovitaminosis D was in 85.14% patients and sufficient in 14.96% patients. BMD was 4.744 ± .9626 gm/cm² in deficient group and -3.274 ± .7502 gm/cm² in sufficient group (p = 0.0001). Vitamin D deficiency was found in 55 patients- male 1 (1.8%) and female 54 (98.2%), Vitamin D insufficiency was in 343 patients-male 13 (3.8%) and female 330 (96.2%), sufficient level in 84 patients. Vitamin D3 level was high in patients living in rural areas than patients living in urban area which was 23.842 ± 8.2157 ng/dl and 19.479 ± 8.7441 ng/dl respectively (p = 0.0001). The mean vitamin 25 OHD level was high among the patients with adequate sunlight exposure than inadequately exposed patients-37.253 ± 5.4884 ng/dl and 19.318 ± 6.6483 ng/dl respectively (p = 0.0001). Hypovitaminosis D showed statistically significant correlation on vertebral fracture and lower BMD level. Conclusion: Hypovitaminosis D was associated to more osteoporotic vertebral fracture. Exposure to sunlight and vitamin D supplementation is recommended to preserve bone health and reduce vertebral fractures.

Declaration of Conflicting Interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This material is the result of work supported with resources and use of facilities at the Zablocki VA Medical Center (ZVAMC), Milwaukee, Wisconsin; the Department of Neurosurgery at the Medical College of Wisconsin (MCW), W81XWH-16-1-0010. The authors NY, MA are part time employees of the ZVAMC. Views expressed in this article are those of the authors and do not necessarily represent the funding organizations.

Reference

1. Hypovitaminosis D and prevalent asymptomatic vertebral fractures in Moroccan postmenopausal women, El Maghraoui et al. BMC Women’s Health 2012, 12:11

P018 - Morphometric Evaluation Of Occipital Condyle: Defining Optimal Trajectories And Safe Screw Lengths For Occipital Condyle-Based Occipitocervical Fixation In Indian Population

Aju Bosco¹, Rishi Mugesh Kanna², Ajoy Shetty³, S Rajasekaran⁴

¹Spine Fellow, Department Of Orthopaedics, Ganga Hospital, Coimbatore - India ²Associate Consultant, Dept of Orthopaedics, Ganga Hospital, Coimbatore - India ³Senior Spine Consultant, Dept of Orthopaedics, Ganga Hospital, Coimbatore - India ⁴Chairman, Dept of Orthopaedics, Trauma & Spine Surgery, Ganga Hospital, Coimbatore - India

Introduction: To analyze feasibility and safety of occipital condyle (OC)-based occipitocervical fixation (OCF) in Indians and to define anatomic zones and screw lengths for safe screw placement. Limitations of occipital squama-based OCF has led to the development of two novel techniques of occipital condyle-based OCF. Materials and methods: Computed tomographic (CT) morphometric analysis. Was performed on OC of 70 Indian adults. Feasibility of placing a 3.5mm-diameter screw into the OC was investigated. Safe trajectories and screw lengths for OC screw and C0-C1 transarticular screw, without hypoglossal canal or atlanto occipital joint compromise were estimated. Results: The average screw length, safe sagittal and medial angulations for OC screws were 19.9 ± 2.3 mm, upto 6.4 ± 2.4 degrees cranially, 31.1 ± 3 degrees medially, respectively. Twenty-seven percent of population could not accommodate an OC screw. Safe sagittal angles and screw lengths for C0-C1 transarticular screw insertion (48.9 ± 5.7 degrees cranial, 26.7 ± 2.9 mm for junctional entry technique; 36.7 ± 4.6 degrees cranial, 31.6 ± 2.7 mm for C1 arch entry technique), showed significant differences compared with other populations. The risk of vertebral artery injury was high with C1 arch entry technique. Aberrant foramen for posterior condylar emissary vein along the screw path (26%) and hindrance to entry point access from overgrowth of posterosuperior rim of C1 lateral mass (22%) were present in 48% of Indians, making screw placement precarious. Conclusion: Ours is the first study to examine the feasibility of OC-based OCF in Indians and to define safe trajectories and screw lengths for the same. T he metrics of OC-based OCF showed significant differences as compared to other populations. Due to smaller dimensions of occipital squama in Indians these techniques may have a higher application rate. OC-based OCF could be viable alternative/salvage options in selected cases. However, they are technically demanding and have a learning curve. If contemplated, preoperative CT including 3D-CT-angiography evaluation (to delineate vertebral artery course) is imperative to avoid complications resulting from aberrant bony and vascular anatomy. The data presented, would serve as a valuable reference-guide in placing these screws safely under fluoroscopy.

P019 - Pedicle Morphometric Study Applied To Screw Positioning

Francisco Ardura¹, Ruben Hernandez-Ramajo², Jesus Crespo², Carlos Jezieniecki³, David Noriega¹

¹Department of Orthopedics, Clinical Hospital. Department of Surgery, School of Medicine, Valladolid - Spain ²Department of Orthopedics, Clinical Hospital, Valladolid - Spain ³Clinical Hospital, Valladolid - Spain

Introduction: Pedicle screws are the most used system for spinal arthrodesis. Pedicle is responsible for 80% of the stiffness of the system and for 60% of the traction forces in the screw-pedicle interfaz. The size of the pedicle is not always regular despite in clinical practice we choose screws as if they were. The objective of our study is to improve surgical planning through the knowledge of the variables that can influence the different morphology of pedicles. Material and Methods: Prospective observational study, in which we included 67 patients. Measurements were done on 670 lumbar pedicles on CT acquired previously including: intracortical and extracortical longitudinal diameter in the anterior, medium and posterior part of the pedicle, and internal and external transverse diameter in the anterior, medium and posterior part of the pedicle. We also included real and effective length and pedicle angle. We classified each pedicle according to the measurements in 4 grades: A (anterior diameter > medium > posterior), B (posterior diameter > medium > anterior), C (anterior and posterior > medium) and D (any other possibilities). We analyzed the relationship between pedicle morphology and age, sex, side, body mass index and comorbidities. We obtained mean and standard deviation for quantitative variables and frequencies distribution for qualitative ones. Rest of statistical analysis was carried out. Results: The most frequent morphology was type C. We found an association between external and internal diameters of 99.6% for transversal diameter and 86.5% for longitudinal diameter. Association between transversal and longitudinal morphology was 86.1% for internal diameters, and 81% for external ones. We found statistically significant differences between left and right pedicles (p < 0.05) in 10 out of 12 L1 vertebras measured, 7/12 L2, 1/12 L3, 2/12 L4 and no L5. Correlation between size of pedicles and height, weight and body mass index were statistically significant. Conclusion: Now a days, it is common that surgeons choose screws according to their experience, and using longer and broader screws as they go down in the spine. Of course, most of them use the same size of screw for both pedicles of the same vertebra. However, our study shows that in our population there are differences, and that this way of choosing screws may lead us to some mistakes. We advise that navigation techniques, preoperative planning based on CT or MRI, and the rest of tools at our disposal, are used to choose in advance the screw that is going to fit best the pedicle and the length of the vertebral body. That way, we will avoid malpositioning and breachs, and we will have a more powerful fixation system. Pedicles’ morphology has a great range of variation. We must use tools to choose the correct screw for every pedicle, in order to achieve optimal results.

P020 - Developmental Spinal Stenosis: A Novel Rat Model With Circumferential Compression

Prudence Wing Hang Cheung¹, Hu Yong¹, Jason Pui Yin Cheung¹

¹Department of Orthopaedics and Traumatology, The University of Hong Kong - Hong Kong

Introduction: Developmental Spinal Stenosis (DSS) is defined as a pre-existing circumferential narrowing of spinal column originating from dorsal spinal elements mal-development, resulting in neural compression. Despite models exist for degenerative spinal stenosis from a one-directional compression mimicking disc protrusions and ligamentum flavum and facet hypertrophy, lumbar DSS requires a new, reproducible animal model which can create a circumferential compression of the dura sac is desirable for future investigation of this disease condition. This study aims to create and validate a model simulating specific bony canal constriction of DSS. Material and Methods: Ten female Sprague-Dawley rats (13.0-14.5 weeks-old) were operated at L4-L5 with circumferential compression (using stainless-steel wire/silicone sheet); dorsal compression (using overlapping silicone sheets), or as controls. Subjects were assessed preoperatively, postoperative 1, 2, 3, 4 weeks and pre-sacrifice at 2 months. Assessment included rung-ladder walking, swimming and electrophysiological test. Basso, Beatie and Bresnahan (BBB) locomotor rating scale, foot-fault scoring, foot placement accuracy analysis and Louisville Swimming Scale (LSS) were used. Axonal demyelination was evaluated histologically by ratio of myelin sheath area to axon area and g-ratio. Group comparison was performed using one-way ANOVA with Post-hoc analysis and Kruskal-Wallis test where appropriate. Results: For BBB scores at flat-rung ladder walking, there was significant difference among study groups (p < 0.05) at postoperative 3-weeks persisting until sacrifice. The statistical significant difference in BBB was demonstrated earlier at one week postoperatively for sloped rung-ladder. At postoperative 3-weeks, circumferential compression had significantly lower foot-fault scores than dorsal compression for right hindlimb, as well as lower foot placement accuracy scores (p < 0.05). LSS was different (p < 0.05) among all study groups at postoperative one month until end-point. Circumferential group using silicone sheets was the only group with increasing and higher P1 and N1 latency for both hind-paws. The mean area ratio of myelin sheath to axons were significantly different between groups: 0.99 ± 0.43 (circumferential – wire), 0.98 ± 0.58 (circumferential-silicone), 1.23 ± 0.73 (dorsal compression), 2.28 ± 1.61 (control) (p ≤ 0.001). The mean g-ratio was significant larger for the circumferential compression (silicone: 0.73) than dorsal compression (0.69) and control (0.58). Conclusion: Our findings validate this created model with specific properties of DSS. Circumferential (wire/silicone) compression group demonstrated little/no hindlimb movements on walking and swimming, high reliance was on forelimbs for forward motion. Their consistently increasing trend of P1 and Ni latency and larger latency indicated somatosensory system deterioration. Neuromonitoring confirms their worst deterioration of somatosensory system than others. This was consistent with the most axonal demyelination in circumferential (wire/silicone) compression than both the dorsal compression and control. This model has successfully simulated DSS and produces characteristic outcomes required for DSS.

P021 - Back Pain And Disc Degeneration Are Decreased By Chronic Toll-Like Receptor 4 Inhibition In An Animal Model

Lisbet Haglund¹, Emerson Krock¹, Magali Millecamps², Jean Ouellet³, Laura Stone²

¹Department of Surgery, McGill University, Montreal - Canada ²Alan Edwards Centre for Research on Pain, 4 Faculty of Dentistry, McGill University, Montreal - Canada ³McGill Scoliosis and Spine Research Group, McGill University, Montreal - Canada

Introduction: Currently, there are no disease-modifying drugs to treat discogenic low back pain. During degeneration, the extracellular matrix is degraded and fragmented, and cytokines, neurotrophins and proteases increase, resulting in further matrix degradation and pain. In vitro work with human disc cells has found that toll-like receptors (TLR) regulate cytokines, neurotrophins and proteases. TLRs are cell-surface pattern recognition receptors that were originally characterized in innate immunity, but are also activated by fragmented extracellular matrix proteins, which are termed ‘alarmins’. Many fragmented extracellular matrix proteins found in the disc, such as fibronectin, aggrecan and hyaluronic acid, can activate toll-like receptors. In humans, matrix alarmins primarily activate TLR2 whereas in rodents they primarily activate TLR4. An increasing amount of in vitro evidence suggests a role for TLRs in disc degeneration, but their role in disc degeneration and pain has not been investigated in vivo. We hypothesized TLR4 inhibition would slow the progression of disc degeneration and reduce pain in a mouse model of disc degeneration and chronic low back pain. The SPARC-null mouse is a well characterized model of age-related disc degeneration and back pain. As the mice age, their lumbar discs progressively degenerate and the mice display several behavioral signs of axial and radiating pain. Material and Methods: 7-month old male wild-type (n = 6/group) and SPARC-null (n = 9/group) mice were injected i.p. with TAK-242 (MedChem Express), a TLR4 specific antagonist, or vehicle. Radiating pain behavior and axial pain behavior was measured. The distance travelled in an open field, performance on a rotarrod test, and changes in weight were evaluated for adverse drug effects. Mice were given a single injection of TAK-242 and pain behavior was assessed 1, 3, 6 and 24 hours after injection. After a 1-week washout, mice were treated 3 times/week for 8 weeks and behavior was assessed weekly. Lumbar discs were excised and cultured for 48 hours. Conditioned culture medium was assessed using a protein array (Ray Biotech). Data was analyzed using one- or two-way ANOVAs with GraphPad Prism. Results: Chronic TLR4 inhibition reduces behavioral signs of back pain in SPARC-null mice likely by acting on degenerating intervertebral discs. If the drug effected neuronal or neuro-immune pain transmission, pain behavior would likely improve after a single treatment or at early time points. However, pain behavior only begins to improve after 6 weeks of TLR4 inhibition. This conclusion is supported by decreased secretion of proinflammatory cytokines. Chronic TLR4 inhibition decreases proinflammatory cytokine secretion in SPARC-null mice to levels similar to that of wild-type mice. Cytokines, such as IL-1β or CCL, can directly act on nerve fibers to cause pain and thus cytokines likely contribute to the pain phenotype in SPARC-null mice. Alarmins that act as TLR ligands, such as fragmented aggrecan, fibronectin and hyaluronic acid are present in degenerating human discs and in vitro cell culture work strongly suggests a roll for TLRs in disc degeneration and pain. Conclusion: This study indicates pattern recognition receptors, such as toll-like receptors, are potential therapeutic targets to slow the progression of intervertebral disc degeneration and manage the associated chronic low back pain.

P022 - Articular Cartilage Degeneration In Adolescent Idiopathic Scoliosis

Daniel Bisson¹, Polly Lama¹, Emerson krock¹, Fahad Abduljabbar¹, Derek Rosenzweig¹, Jean Ouellet², Lisbet Haglund¹

¹Department of Surgery, McGill University, Montreal - Canada ²McGill Scoliosis and Spine Research Group, McGill University, Montreal - Canada

Introduction: The 3-dimmensionnal conformation of the spine in AIS patients forces abnormal biomechanical stresses on the load-bearing organs. The curvature generates a load pattern much different to the ones in healthy individuals, where the weight is balanced on an axis of symmetry along the spine. It is known that adverse loading on articular cartilage can lead to degeneration and pain, but it has never been studied in the context of this pathology. Therefore, our objective is to characterize the facet joint cartilage in AIS patients and in the case of onset degeneration, to explore the causes and molecular mechanisms that contribute to cartilaginous tissue breakdown. The degeneration hallmarks were assessed by histology, gene expression and protein arrays. As for the contributing mechanisms, the Toll-like receptor (TLR) pathway was studied. TLRs are pattern recognition receptors that can recognize pathogens and endogenous proteins such as fragmented extracellular matrix components present in intervertebral discs (IVD) and articular cartilage. Once activated, they trigger a molecular cascade resulting in pro-inflammatory cytokines, proteases and neurotrophins which can lead to matrix catabolism, inflammation and potentially pain. Recently, some TLRs such as TLR2 was seen to increase in IVD degeneration and osteoarthritis but hasn’t been studied in the context of AIS. Material and Methods: Facet joints of Adolescent Idiopathic Scoliosis patients undergoing corrective surgery and of cadaveric donors (non-scoliotic) were collected from consenting patients or organ donors. Cartilage was removed from the bone under sterile conditions. Cartilage biopsies and chondrocytes were isolated respectively. The other biopsies was treated for 4 days with or without a TLR2 agonist. Biopsies were fixed for histology. Isolated chondrocytes were treated for 6 h with Pam2CSK4. RNA expression was evaluated with RT-qPCR. Presence of protein fragmentation was assessed by Immunoblotting. Statistical analysis was performed with a parametric student t-test. Results: Cartilage from AIS facet joints have significantly less proteoglycan content and a higher OARSI score. Cell density in histological slides was significantly higher in scoliotic tissues overall but also a constant discrepancy in cellularity between the two facets from one vertebra was seen. The proliferative marker KI-67 was significantly overexpressed in the scoliotic donors, with the percentage of cells with positive staining being elevated in the facets with higher cellularity. The baseline gene expression analysis showed an upregulation in TLR2 and IL-1b when comparing with the non-scoliotic control group. Furthermore, TLR2 gene expression correlated positively with other degenerative markers such as MMP-3, -13, IL6, IL8 and IL-1b. The biopsies which were treated with Pam2CSK4 had a significant loss of proteoglycan content as shown by histology. Finally, the presence of fragmentation in multiple extracellular matrix components and known alarmins within the scoliotic cartilage such as decorin, lumican and chondroadherin was seen increasing with the severity of the curve. Conclusion: Both red staining quantification and OARSI grading of Safranin O-Fast Green histology shows degenerative changes in scoliotic facet joints compared to the control group, which has a higher mean age. Combined with abnormally high cell density and upregulated TLR2, IL-1b gene expression, we can conclude that facet joints in AIS patients present the hallmarks of early onset cartilage degeneration. The higher cell density might be part of a repair mechanism to counterbalance the matrix destruction with increased anabolism through cell proliferation as shown by KI-67 histology.

P023 - Objectification Of Surgical „Basic Skills“ By A Simulated Mircodisectomy

Christoph Mehren¹, Werner Korb², Luis Bernal², Eszter Fenyöhazi², Davide Iacovazzi², Michael Mayer¹

¹Spine Center Schön Klinik München Harlaching, Munich - Germany ²Hochschule für Technik, Wirschaft und Kultur (HTWK) Leipzig, Leipzig - Germany

Introduction: Several studies could demonstrate „learning curves“ in almost every single surgical procedure for unexperience surgeons. This fact is in strict contrast to the rising quality requirements in public health care respectively to provide surgical training at patients „expense“. Beside the „know how“ of each technical step of a surgical procedure especially individual „basic skills“ like fine motor skills, hand-eye-coordination and visual thinking matters in microsurgical spinal interventions. Aim of this study was to prove if you could measure surgical experience and individual skills via a decreased load on the nerve root during a simulated and standardised microdiscectomie on a validated model (Realspine^®) respectively to identify surgical „talents“ at the initial phase of surgical training. Material and Methods: Within a government founded project 5 highly experienced spine surgeons (over 2000 microsurgical procedures each) and 5 trainees without considerable surgical experience as been elected to perform a standardised microsurgical discectomy on a validated Realspine^®-Simulator. Force sensors were integrated in this simulator to measure and objectify the acting load on the spinal canal and the nerve root L5. This measurement system captures the contusion and tension forces along the nerve root. The forces were recorded every 125 ms in Newton. Results: Average duration of this procedure was 36.47 minutes for the trainees and 14.16 minutes for the expert-group. We could identify cumulative for the total intervention as well for defined single surgical steps of this procedure and as well in between the single subjects a significant higher tension and contusion forces on the nerve for the trainee-group (Δp contusion 83Ns - 765Ns and Δp tension 159Ns - 1131Ns for the trainees resp. Δp contusion 16Ns - 171Ns and Δp tension 27Ns - 146Ns for the experts). This observation is comprehensible for the applied forces in every single step of this intervention in both groups. The highest applied forces in every single step were comparable in both groups, however in a significant reduced period of time fort he expert group. Discussion: We could proof and measure within this pilot study a significant difference between unexperienced and experienced spine surgeons regarding the manipulations of the nerve root during a standardised simulated microdiscectomy. This possibility could be the starting point for a new and innovative surgical education in spinal interventions especially to improve the patients outcome without the negative side effects of „learning curves“ due to the possibility to practice on validated and realistic models.

P024 - Morphometric Evaluation Of Lateral Masses Of Subaxial Cervical Spine In Indians: A Critical Evaluation Of Optimal Trajectories And Safe Screw Lengths For Lateral Mass Fixation

Aju Bosco¹, Nalli Ramanathan Uvaraj²

¹Center for Advanced Brain and Spine Surgery (CABSS), Tamilnadu Govt. Multi Superspeciality Hospital, Chennai - India ²Spine Surgery Unit, Department of Orthopaedics and Traumatology, Madras Medical College and Rajiv Gandhi Govt. General Hospital, Chennai - India

Introduction: Among the posterior cervical fixation techniques, lateral mass screw fixation has become the method of choice in stabilizing the subaxial cervical spine whenever the posterior elements are absent or compromised.Many studies are available on the morphology of the lateral masses of the Western race.To the best of our knowledge, there is no data available on the morphometry of lateral masses of the subaxial cervical spine of the Indian population.We did a morphometric analysis of the lateral masses of subaxial cervical spine of normal adult Indian population, to analyse the morphologic differences as compared to the Western race and to establish guidelines for safe lateral mass instrumentation. Materials and Methods: Morphometric analysis of the lateral masses of C3 to C7 vertebrae in 60 Indian adults, was performed using high resolution multislice helical computed tomography (CT) scan with multiplanar reconstruction. Descriptive statistics were computed for all measurements, using SPSS software (v.22). Morphometric differences were analysed using Student t-test, (p < 0.05 was statistically significant). Results: For almost all levels and measurements male and female values were significantly different (p < 0.05).There were significant differences between the morphometry of Indian and the Western race.The lateral masses were wider (axial width) and taller (sagittal height) in the Western race contrary to the Indian race, where they were marginally thicker in females (sagittal thickness). The facetal angulation (FA) of the Indian race showed a 4⁰ decrease between each level moving caudally from C3 to C6, while an 8⁰ decrease was observed between C6 and C7.The FA was higher in women than in men, at most levels as against the Western population, where the values were consistently smaller in women. The Safe Divergent Angle (SDA) for screw placement showed a progressive increase at each successive caudal level.The SDAs for lateral mass screw placement progressively increased between each level as we moved caudally. The findings of this study also highlight the need for necessary modifications of the known surgical techniques to suite the Indian population. Conclusions: This is the most extensive anatomic evaluation of the lateral masses of subaxial cervical spine in Indians and the first to examine, the facetal angulation of each facet joint relative to a posterior surgical approach. We found significant morphometric differences between the Indian and the Western race. These morphometric differences have implications for placing lateral mass screws safely and effectively. SDA for each level of the subaxial cervical spine have been defined, and are different for each level. Hence, it is not advisable to adopt a fixed SDA for all levels of subaxial cervical spine. Preoperative thin-slice CT is essential for planning screw trajectories. Due to the fact that the C7 lateral mass thins out caudally, the conventional entry point may lead to violation of the C7-T1 facet joint, inferior articular process fracture, inadequate purchase and potentially, to intrusion into the C7-T1 foramen.Hence, C7 lateral mass screw placement may be initiated a little higher than the conventional entry point(Magerl technique) to facilitate a safe trajectory. The finding of a decrease in sagittal width suggests that a slightly shorter screw may be used for C7 lateral mass fixation.

Keywords: lateral mass, cervical spine, morphometry, Indians

Source of Funding-NIL; Conflicts of interest-NIL.

Biomechanics

P025 - Sagittal Balance Of The Spine In The Patients With Achondroplasia In Limb Lengthening Using Ilizarov Method

Oxana Prudnikova¹, Anna Aranovich²

¹Neurosurgery Department, Kurgan - Russian Federation ²Orthopaedic Department, Ilizarov Center, Kurgan - Russian Federation

Introduction: Spinal stenosis and sagittal imbalance are the most common changes in the patients with achondroplasia (Hong J.-Y., 2011, Kolesov S.V., 2013, Misra S.N., 2013). Ilizarov transosseous compression – distraction osteosynthesis gives the possibility to lengthen the lower limbs for 28-30 cm in achondroplasia. That raises the question on how the limb length changes are reflecting in the spine condition. Purpose is to study the peculiarities of the sagittal balance of the spine in achondroplasia patients at the stages of lower limbs lengthening using Ilizarov fixator. Materials and Methods: Clinical and radiological study of 20 achondroplasia cases was performed at the different stages of the lower limb lengthening using Ilizarov method. The parameters of sagittal balance were evaluated radiologically. The clinical assessment was based on the clinical examination, neurological status (Skoromets A.A., Skoromets T.A., 2002) and pain scale (Wong-Baker numerical Pain Rating Scale, 2011). Results and Discussion: Hypokyphosis of the thoracic spine in 100% of the cases and increase of the lumbar lordosis in 62.5% were clinical manifestations of the sagittal balance. No neurological disorders were diagnosed in the patients. Pain syndrome ranged from 2 to 4 points in 25% of the cases. Kyphotic deformity of the spine on the background of wedge-shaped deformities of L1 and L2 vertebral bodies was diagnosed in five (31.5%) cases with local angular kyphosis (16.8 ± 8.2°) at the level of Th10-L2. After stage-by-stage lower limbs lengthening for 14.7 ± 5.7 cm we observed the increase of the lumbar lordosis indices and pelvic index and the reduction of the pelvic tilting angle. Conclusion: We revealed true correlation of the sagittal balance indices such as vertical sagittal axis and pelvic coefficients, thoracic kyphosis and lumbar lordosis, lumbar lordosis and pelvic parameters. Lower limb lengthening using Ilizarov method improved the indices of the balance of the spine such as increase of the pelvic index, angle of the pelvic tilting and lumbosacral angle up to the indices of the healthy age-mates. We think it is caused by high correlation dependence of the lower limb lengthening amount and pelvic coefficients. Currently we continue this work for comparative analysis of the results in the patients at all stages of follow-up.

P026 - Biomechanical Comparison Of Cemented Versus Non-Cemented Screw Fixation In Type Ii Odontoid Fractures In Elderly - A Cadaveric Study

Petr Rehousek^1,2, Edward Jenner, Marcin Czyz¹, James Holton¹, Jiri-Skala Rosenbaum^1,2

¹Department of Spinal Surgery, Royal Orthopaedic Hospital, Birmingham - United Kingdom ²The Third Medical Faculty, Charles University, Prague-Czech Republic

Introduction: Odontoid peg fractures are the most common injuries of the cervical spine in the elderly. Anterior screw stabilisation of type 2 odontoid peg fractures improves survival and function in these patients but may be complicated by failure of fixation. The aim of this study was to determine whether cement augmentation of a standard anterior screw provides biomechanically superior fixation of type II odontoid fractures in comparison to an non-cemented standard screw. Material and Methods: Twenty human cadaveric C2 vertebrae from elderly donors (mean age 83 years) were prepared. Anderson and D'Alonzo type IIa odontoid fracture was created by transverse osteotomy and fluoroscopy guided anterior screw fixation was performed. The specimens were divided into two matched groups. The cemented group (n = 10) had radiopaque high viscosity polymethylmethacrylate cement injected via Jamshidi needle into the base of the odontoid peg. The other group was not augmented. A V-shaped punch was used for loading the odontoid in an antero-posterior direction until failure. The failure state was defined as screw cut-out or 5% force decrease. Mean failure load and bending stiffness were calculated. Results: The mean failure load for the cemented group was 352.1 ± 163.8 N compared to 198.2 ± 81.9 N for the uncemented group (P = 0.02). The mean bending stiffness of the uncemented group was 153.2 ± 71.9 N/mm compared with 195.3 ± 76.5 N/mm for the cemented group (P = 0.159). Conclusion: Cement augmentation of an anterior standard screw fixation of Type II odontoid peg fractures in elderly patients significantly increased load to failure under anterior posterior load in comparison to non-augmented fixation This may be a valuable technique to reduce failure of fixation.

P027 - Sagittal Vertical Axis And Spinopelvic Parameters In Healthy Individuals

Sai Krishna M L V¹, Deep Sharma², Jagdish Menon³

¹Senior resident, Dept of Orthopaedics, Jipmer, Puducherry - India ²Addl Professor & Head, Dept of Orthopaedics, Jipmer, Puducherry - India ³Professor, Dept of Orthopaedics, Jipmer, Puducherry - India

Introduction: With the discovery of sagittal spinopelvic parameters and their association with various spine disorders, the concept of sagittal balance has become very important. Alteration in sagittal profile has been documented to be associated with various spine disorders from degenerative diseases to deformity. Overall sagittal profile can be assessed with the help of Sagittal Vertical Axis (SVA). SVA is defined as plumb line dropped from C7 vertebra on a lateral sagittal spine radiograph taken in standardized way and its horizontal distance measured from anterior superior corner of sacrum. Based on previous studies the horizontal distance ranges from -4.5 to +14.9 cm. HRQOL (Health Related Quality Of Life) has highest correlation with T1 tilt, SVA, pelvic tilt. SVA within 5 cm has been associated with better quality of life. We started our study to know the relation between SVA and spinopelvic parameters in asymptomatic Indian population. Materials and Methods: The study was approved by our institute review board and the ethical committee. A total of 75 young, healthy and asymptomatic volunteers were enrolled into the study after taking a formal consent. Lateral sagittal digital radiographs of the whole spine. The parameters measured were pelvic incidence PI, pelvic tilt PT, sacral slope SS, thoracic kyphosis TK, lumbar lordosis LL, SVA. All measurements were performed using the Surgimap spine software version 2.1.2. Subjects are divided into two groups based on SVA (≤ 5 cm & > 5 cm). Comparisons are drawn between the groups. Results: The mean values in the first group (SVA ≤ 5 cm) are PI-46.75, PT-12.74, SS-34.03, LL-53.54, TK-23.86. In the second group (SVA > 5 cm) are PI-60.50, PT-16.33, SS-44.17, LL-67.83, TK-26.00. There was a significant difference between the groups among PI, SS, LL (0.01 < p ≤ 0.05). Conclusion: Subjects with SVA >5 cm. have higher pelvic incidence, sacral slope and lumbar lordosis which was statistically significant.

P028 - Post-Implantation Deformation Of Titanium Rod And Cobalt Chrome Rod In Adolescent Idiopathic Scoliosis

Ung Sia¹, Boon Beng Tan², Yian Young Teo², Chung Chek Wong¹

¹Department of Orthopaedic, Sarawak General Hospital, Kuching - Malaysia ²Department of Orthopaedic, University Malaysia Sarawak, Kuching - Malaysia

Introduction: Thoracic adolescent idiopathic scoliosis (AIS) is a 3-dimensional coupling deformity. Pedicle screw rod construct as a gold standard provides the ability to manipulate all three spinal columns and offers the stiffest construct. Coronal correction has been emphasized in the past, but the sagittal balance has emerged as an important factor to be reckoned with. There is still lack of guideline in determining differential rod contour. Post-implantation rod deformation is anticipated but the difference in rod deformation between titanium and cobalt chrome rod has not been elucidated. Material and Methods: The aims of this prospective study are to determine the degree of rod deformation post-implantation, evaluate the effect of direct vertebral rotation (DVR) on thoracic kyphosis (TK) and compare postoperative TK between titanium and cobalt chrome rod following segmental DVR. Twenty-one AIS patients were recruited from June 2013 till May 2015. The over-contoured concave rod shapes were traced prior to insertion. Postoperative sagittal rod shape was determined from lateral radiographs. Maximal rod deflection and angle of the tangents to rod end points were measured. The differences between pre- and postoperative rod contour were analysed statistically. Additionally, comparison of TK pre- and post-operation between two types of implants was performed. Results: Pre-operative Cobb angle of 60.4° (SD 16.05) was successfully corrected to 19.8° (SD 10.39), with a mean correction rate of 68.3%. TK was increased from 24.4° to 30.3° in titanium group but a reduction from 25.5° to 22.7° was noticed in cobalt chrome group. Despite an apparent difference in mean TK postoperatively, these findings were not statistically significant (p = 0.644). The mean reduction of rod angle of titanium and cobalt chrome was 23.6° and 20.3° respectively. There was significant change of rod angle post implantation (p < 0.001). The average magnitude of deflection for titanium rod and cobalt chrome rod was 6.9 mm and 7.8 mm, respectively. Both titanium and cobalt chrome rods were flattened, with a significant decrease in deflection (p < 0.001). However, there is no significant difference between titanium and cobalt chrome group with regard to rod angle and deflection. Conclusion: There was no statistical difference in rod deformation between AIS patients treated surgically using titanium rod and cobalt chrome rod. Application of DVR does not worsen thoracic hypokyphosis. Choosing titanium or cobalt chrome rod as spinal deformity surgery can be based on surgeon’s preference.

P029 - Attenuation Of Proximal Junctional Kyphosis Using Sub-Laminar Polyester Tension Bands

Samuel Cho¹, John Caridi¹, Jason Inzana², Anup Gandhi²

¹Departments of Orthopaedics and Neurosurgery, Mount Sinai Hospital, New York - United States ²Zimmer Biomet, Westminster - United States

Introduction: Proximal junctional kyphosis (PJK) is a common post-surgical complication following long spinal fusion for deformity. Multiple risk factors are associated with PJK, including patient, radiographic, and surgical variables. It is commonly hypothesized that PJK may result from increased post-operative loading of the posterior ligament complex or intra-operative damage to the ligaments themselves. The aim of this study was to investigate the effect of sub-laminar polyester tension bands on the biomechanics of the motion segment proximal to a long fusion construct. Material and Methods: Eight human thoracolumbar spines (T7-L2) were dissected and the end vertebrae were partially embedded in bone cement. Pure moments of 4 Nm and 8 Nm were applied to the native spine and the instrumented spine, respectively, in flexion-extension (FE), lateral bending (LB), and axial rotation (AR). The increased load on the instrumented spines was designed to represent the increased post-operative loads that may result from decreased extensor muscle strength or inertial effects adjacent to a stiff fusion construct. The test conditions included: native spine (T7-L2), fused (T10-L2), fused + bilateral bands tensioned to 250 N at T9-T10 (Bands 250 N), fused + Bands tensioned to 350 N (Bands 350 N), fused (T11-L2) + Bands tensioned to 250 N at T9-T10 and 350 N at T10-T11 (2-Level Bands), fused (T10-L2) + hand-tied suture loop through the spinous processes at T9-T10 (Suture Loop), and fused (T10-L2) with the T9-T10 interspinous and supraspinous ligaments cut (Cut ISL/SSL). Results: The flexion range of motion (ROM) at T9-T10 of the fused spine, loaded at 8 Nm, increased to 162% of the native spine loaded at 4 Nm. The average flexion ROM at T9-T10 for Bands 250 N, Bands 350 N, 2-Level Tethers, Suture Loop, and Cut ISL/SSL were 85%, 70%, 93%, 141%, and 177% of the native spine at 4 Nm, respectively. Each of these conditions was significantly different from Fused (p < 0.05). The tension bands did not significantly affect the ROM in LB or AR. Conclusion: Biomechanical models of PJK assume that an increased load exists at the proximal segment following fusion, as was observed in this model. As expected, cutting the ISL/SSL ligament complex significantly compromised the flexion stability of the spines, which may be associated with greater PJK risk. On the other hand, the flexion ROM was modulated by varying the tension of the sublaminar bands, which reduces the loads on the posterior ligament complex. However, future studies should identify the optimal tension that will not induce sagittal imbalance or fusion, but will support the spine while the patient adapts to the fusion.

P030 - Coupled Translational Movements Of The Sacroilliac Joint: An In-Vitro Study

Khalid Odeh¹, Ben Taylor², Connor Purviance², Gio Gajudo², Jeremi Leasure², Dimitriy Kondrashov¹

¹San Francisco Orthopaedic Residency Program, San Francisco - United States ²The Taylor Collaboration, San Francisco - United States

Introduction: Increasing attention has been given to the sacroiliac joint (SIJ) as a source of low back pain, despite a limited range of motion. Fusion of the SIJ seeks to minimize this movement as a possible pain generator. Coupled motion is described as the phenomenon of consistent association of one motion about an axis with another motion about a second axis. Our study aimed to develop a more comprehensive understanding of the native motion of the SIJ within the context of spinal kinematics and spinal implant evaluation. We sought to characterize the translational motion in each axis utilizing the standard flexion-extension (FE), lateral bending (LB), and axial rotation (AR) testing. Our hypothesis was that current descriptions do not fully describe SIJ motion given the possibility of coupled motions. Methods and Materials: Eight human lumbosacral cadaver specimens (6 female, 2 male) were harvested from subjects aged 28-57 (mean age 46.8) with BMI 22-36 (mean BMI 30). Both ischia were potted in two separate blocks of epoxy resin, and the L4 endplate was secured in a cylindrical potting. Single leg stance was modeled by clamping the blocks on one ischium in a vise and letting the contralateral ischium hang freely. Pure moment loading was applied in the directions of FE, right/left AR, and right/left LB. Three preconditioning cycles were run, then a final cycle applied a moment from 0 to 7.5 Nm in 1.5 Nm increments; data was taken from the final cycle. Relative motions between the sacrum and iliac wings were collected with an Optotrak system and infrared markers. We defined on-axis rotation as the component rotation in the same plane as the loading moment, resultant translation as the Pythagorean sum of the three translation components, and in-plane translation as the Pythagorean sum of the two component translations in the same plane as the loading moment. Results: In FE loading, on-axis rotation measured 2.65 ± 1.71°, resultant translation was 1.87 ± 1.43 mm, and in-plane translation was 1.80 ± 1.43 mm. In AR loading, on-axis rotation measured 1.77 ± 1.25°, resultant translation was 1.57 ± 1.13 mm, and in-plane translation was 1.38 ± 0.97 mm. In LB loading, on-axis rotation measured 1.16 ± 1.16°, resultant translation was 1.50 ± 1.23 mm, and in-plane translation was 1.20 ± 1.13 mm. In-plane translation was significantly higher (p = 0.005) in FE loading than in LB loading. The correlation between on-axis rotation and resultant translation is highest in AR loading (r ² = 0.813) and lower in FE and LB loading (r ² = 0.685 and r ² = 0.667, respectively). Conclusion: A non-trivial amount of translation occurred out of the expected plane of motion in our in vitro study. Relative to resultant translation, in-plane translation was lowest in LB. Our results indicate that translation of the SIJ is not fully described with the in-plane metrics which are normally reported in evaluation of fusion devices. Future studies of the SIJ may need to consider including translation measurements when describing SIJ kinematics.

P031 - Biomechanical Evaluation Of Fusion Constructs Using Posterior Interbody Spacer With Integrated Anchors And Less-Invasive Adjunctive Posterior Fixators

Antoine Gennari¹, Stéphane Litrico², Sylvain Persohn¹, Tristan Langlais¹, Jérome Allain³, Wafa Skalli¹

¹Institut de Biomécanique Humaine Georges Charpak, Paris - France ²Neurosurgery, Spine Unit CHU Pasteur, Nice - France ³Clinique Geoffroy Saint Hilaire, Paris - France

Introduction: The purpose of this study was to investigate the biomechanical behavior of TLIF and PLIF constructs that included both an anchored interbody spacer (IBS) and one less invasive adjunctive posterior fixator, either transfacet screw (TFS) or interspinous anchor (ISA), respectfully. The behavior of these TFS and ISA fixators were compared with those of traditional bilateral pedicle screws (BPS).

Material and Methods:

• Study protocol

We used twelve fresh human cadaveric lumbar spine segments from L3 to the sacrum. Radio-opaque markers were fixed on the L4 and L5 vertebrae.

All specimens were biomechanically tested in the intact condition (INTACT). Then, specimens were separated into two groups:

In the TLIF Group, IBS with anchor inserted obliquely at L4-L5 was tested alone (INSTR1) and with the following posterior constructs: contralateral TFS (INSTR2), BPS (INSTR3) and ipsilateral unilateral pedicle screw (UPS) (INSTR4).

In the PLIF Group, two IBS with anchors were evaluated alone (INSTR1) then, with adjunction of ISA (INSTR2) and BPS (INSTR3).

• Biomechanical testing

We applied pure moments (7.5 Nm by increments of 1.5 Nm) in flexion-extension (FE), lateral bending (LB) and axial rotation (AR) with no axial pre-load.

• Specimen motion analysis

The test bench was integrated into a biplanar X-rays system (EOS Imaging). Biplanar radiographic images were acquired at each loading increment.

L4–L5 intersegmental motion was calculated by measuring the relative displacement of the radio-opaque fiducial markers of L4 with respect to L5.

• Data analysis

Range of motion (ROM) was analyzed for each configuration. A Wilcoxon statistical test was used to compare the ROM of conditions with the significance set at p < 0.05.

Results:

• TLIF Group

The IBS (INSTR1) lowered ROM in FE and AR when compared to the INTACT.

The addition of contralateral TFS (INSTR2) significantly decreased ROM in each direction compared to INTACT. Compared to the INSTR1, INSTR2 significantly reduced ROM in LB and AR. The lowest ROM were observed with the BPS (INSTR3). TFS (INSTR2) compared to UPS (INSTR4) lowered ROM in FE and in AR.

• PLIF Group

The IBS (INSTR1) lowered ROM in FE and LB compared to INTACT but significantly increased the mobility in AR.

The addition of ISA (INSTR2) significantly reduced ROM from the IBS alone (INSTR1) in all directions. BPS configuration (INSTR3) significantly reduced ROM in LB and AR when compared to ISA construct (INSTR2); the difference was 0.4° in FE.

• TLIF/PLIF Groups

With the IBS alone (INSTR1), PLIF provided less mobility than TLIF during FE and LB but not in AR. The PLIF with ISA (ISNTR2) provided more stability than TLIF with TFS (ISNTR2) in FE but not in AR and LB. The decrease in ROM with BPS (INSTR3) is comparable between PLIF and TLIF Groups.

Conclusion: Using an original testing device integrated with an EOS X-ray system, this study investigated the immediate stability of posterior lumbar fusion constructs. Those new configurations, using fixed posterior IBS in addition with TFS or ISA, reduced ROM and provided stability when compared to the intact condition. These techniques could provide an interesting alternative to the classic BPS.

P032 - Finite Element Model Of The Cervical Spine For Cervical Anterior Discectomy

Andrei Stefan Iencean¹, Stefan Mircea Iencean²

¹Neurosurgery, N Oblu Hospital, Iasi - Romania ²Neurosurgery, GrT Popa University of Medicine and Pharmacy, Iasi - Romania

Introduction: We used a finite element model of the cervical spine consisting of 739 666 elements and 210 530 nodes to determine the risk of postoperative cervical instability in relation to the type of anterior cervical discectomy at a single cervical level: without fusion and with fusion. Materials and Methods: Three cervical spine models were studied by finite element method: normal cervical spine, cervical spine with anterior microdiscectomy at C6-C7 level and cervical spine with C6-C7 discectomy and cage stabilization. Flexion and extension movements were simulated starting from the cervical intermediate position by applying a moment of force of 1 Nm. Results: It is found that surgery decreases postoperative mobility compared to the normal cervical spine more for the flexion movement and the cage at the C6-C7 disk space reduces overall mobility by 26% in flexion versus the mobility of the normal cervical spine. In the case of microdiscectomy without fusion, the overall cervical mobility decreased by 8.76% compared to the unoperated model. Conclusion: The limitation of the amplitude cervical motion is greater in the case of discectomy with fusion compared to microdiscectomy without fusion with a decrease in the amplitude of the movements of 3:1 between the operated models.

P033 - Is There Any Difference In Saggital Balance Correction - Tlif Vs Plif - A Retrospective Study

Inês Mafra¹, Alexandra Santos², Ana Luís², Carla Reizinho²

¹Orthopaedics Department, Centro Hospitalar Barreiro-Montijo, Barreiro - Portugal ²Neurosurgery Department - Centro Hospitalar Lisboa Ocidental, Lisboa - Portugal

Introduction: Degenerative lumbar disease (DLD) is characterized by a progressive loss of lumbar lordosis. Recent studies point out Sagittal balance analysis to be a cornerstone for optimal treatment of DLD, whereas sagittal imbalance is correlated with poor outcomes. The best surgical procedure is still controversial, although Posterolateral interbody fusion (PLIF) and Transforaminal interbody fusion (TLIF) have shown similar fusion rates. Our purpose was to evaluate sagittal balance correction in patients submitted to PLIF and TLIF. Methods: A retrospective analysis of patients treated with PLIF and TLIF was conducted in our department, between January 2014 and December 2015. Incomplete pre or post-operative planning and incomplete clinical records were excluded. Clinical variables such as age, gender, primary diagnosis, number of fused levels, surgical technique and pre and post-operative radiographs were evaluated. Assessment of Pelvic Incidence (PI), Pelvic Tilt (PT), Sacral Slope (SS) and Lumbar Lordosis (LL) was made based on radiographs. Results: 87 patients were evaluated, where 20 patients were included, 75% females and 25% males, with a mean age of 61 ± 13 years. Primary pre-operative diagnosis were isolated spondylolisthesis, associated with disc herniation or central canal stenosis and failed back surgery syndrome, in 55%, 10%, 15% and 20% respectively, with primary involvement of L4-L5 level. We performed PLIF in 45% and TLIF in 55% of cases, at one (60%), two (35%) or three levels (5%). Mean pre-operative PI was 54, with a mean PT of 14º, SS of 40º and LL of 61º. Mean post-operative values were PT of 15º, SS of 41º and LL of 62º. No correlation was found between the surgical technique, TLIF or PLIF, and the correction of pelvic (p = 0,299) and lumbar parameters (p = 0,82). Also the number of fused levels and restoration of PT (p = 0,698), SS (p = 0,334) and LL (p = 0,918) presented no correlation. Conclusions: Preoperative sagittal balance assessment is important in estimating the necessary spinal correction, being associated with better clinical outcomes. Our reduced sample analysis failed to suggest any superiority between TLIF or PLIF for sagittal balance restauration, hence both procedures are valid choices depending on the surgeon’s preference.

P034 - Biomechanical Study On Proximal Junctional Kyphosis Following Long-Segment Posterior Spinal Fixation

Wenyi Zhu¹, Yong Hai¹

¹Department of Orthopedics, Beijing Chaoyang Hospital, Capital Medical University of China, Beijing - China

Introduction: Lumbar degenerative disease (LDD) is a common medical disorder in middle-aged and elderly populations. Surgery is currently the mainstream treatment for LDD. The most commonly used surgical procedure for treating LDD is posterior spinal fusion with pedicle screws. However, long-segmental fixation leads to stress concentration at both ends of the screws, resulting in proximal junctional kyphosis (PJK). To identify the optimal fusion sites for posterior long-segment internal fixation using finite element analysis. Materials and Methods: Finite element models were constructed based on the whole-spine computed tomography findings of a healthy adult. Eight commonly used posterior internal fixation methods were selected: L4–L5, L3–L5, L2–L5, L1–L5, T12–L5, T11–L5, T10–L5, and T2–L5. Changes in the stresses on the fixed and non-fixed functional spinal unit of the upper instrumented vertebra (UIV) and the vertebra above it (UIV+1) in an upright position were simulated. The changes of each of the normalized indicators was also analyzed. Results: The experimental modes were divided into non-fixation and fixation groups. In the non-fixation group, the stress on T10 was high and mainly distributed in the front of the vertebra. In the fixation group, the stresses on UIV and UIV+1 were markedly higher than those in the non-fixation group, and mainly distributed at the rear of the vertebrae. The peak stress values on UIV were mainly seen in L2 and T2, compared with T10 and L2 on UIV+1. After normalization, the peak stress values of both UIV and UIV+1 were located in L2 and T2. Similarly, the peak stress values on fibrous rings were concentrated on T9/T10 and segments above them after normalization. Conclusions: Fusion of UIV to L2 or upper thoracic segments should be avoided to prevent PJK. Fusion to the lower thoracic segments (e.g. T10–T12, especially T12) may be more feasible.

P035 - The Biomechanical Effects On Adjacent Segments After Two-Level Acdf With Reduced Lordosis

Chuan Pang¹, Yong Hai¹

¹Department of Orthopedics, Beijing Chaoyang Hospital, Capital Medical University of China, Beijing - China

Introduction: To study the biomechanical effect on adjacent segments of anterior cervical discectomy and fusion (ACDF). Materials and Methods: 6 adult human cervical spine specimens (C2-C7) were tested under the following 3 conditions: intact cervical spine group, C4-6 ACDF with normal lordosis group, C4-6 ACDF with reduced lordosis group. The specimens were tested in flexion, extension, bending and rotation on the spine 3D motion experiment system. The Cobb angle, overall range of motion(ROM), ROM and loads of facet joints at adjacent segments were measured. Results: The lordosis Cobb angle was l 3.5° ± 4.1 o in intact cervical spine group, 15.70 ± 4.6° in C4—6 ACDF with normal lordosis group, 9.00 ± 4.0° in C4—6 ACDF with reduced lordosis group, respectively. After operation the overall ROM of specimens reduced in flexion, extension, bending and rotation, but the ROM of upper and lower adjacent segments increased. The ROM of upper segments(C ˙  )in flexion and extension, as well as that of lower segments (C6—7)in flexion, extension and rotation, had significant difference. The extension ROM of upper segment (C3_4) of C4—6 ACDF with reduced lordosis group was found greater than that of C4—6 ACDF with normal lordosis group and the flexion and extension ROM at lower segment(C6-7)of C4—6 ACDF with reduced 10rdosis group were also greater. Increased max and average stress on C 3-4 facet joints was observed in all the 4 types of motion after ACDF and the differences in extension and bending were statistically significant. Comparing C4—6 ACDF with reduced lordosis group and C4—6 ACDF with normal lordosis group, a stress decreasing trend was observed along with the reduced lordosis angle but had no significant difference. Conclusion: After 2 level ACDF on cervical spine specimens, ROM of adjacent segments and stress on facet joints increased. The ROM of specimens with reduced lordosis is higher than those with normal lordosis, which may accelerate ASD.

P036 - Effect Of Microdiscectomy On The Kinematics Of The Lumbar Facet Joints

Sheri Imsdahl¹, Richard Bransford², Michael Lee³, Randal Ching¹

¹Department of Mechanical Engineering, University of Washington, Seattle - United States ²Department of Orthopaedics and Sports Medicine, Harborview Medical Center, Seattle - United States ³Department of Orthopaedic Surgery and Rehabilitation Medicine, University of Chicago Medical Center, Chicago - United States

Introduction: Microdiscectomy is the most commonly prescribed surgery for lumbar disc herniation and can be performed in partial (PD) or subtotal (SD) fashion. SD involves excision of the herniated fragment with aggressive curettage of the disc space, while PD is more conservative and emphasizes limited disc invasion. The choice between PD and SD remains unclear, and there are limited data regarding their biomechanical effects on the intervertebral joint. It has been hypothesized that abnormal or increased facet motion may lead to subtle shifts in the load distribution on the articular surfaces, ultimately facilitating cartilage degeneration [1,2]. Thus, the purpose of this study was to determine how these procedures affect the relative kinematics of opposing facet surfaces at the level of surgery. Material and Methods: Fiducial markers (CT beads) were attached to each vertebra of nine human cadaveric lumbar spines. The specimens were CT-scanned, and the images were segmented to obtain a 3D model of each specimen. The specimens were subjected to pure moment testing in their intact condition and post-PD and SD at L3-L4. Both surgeries entailed a left laminotomy with an annular window. For PD, a small fragment of disc was removed, and for SD, 2 grams of disc were excised. In each condition, the specimens were tested to ± 10 Nm in: flexion-extension, lateral bending, axial rotation, and two combinations of flexion-extension with lateral bending. The vertebral kinematics were tracked with an optoelectronic system. The relative kinematics of opposing facet surfaces were determined at L3-L4 by registering the specimens’ vertebral kinematics to their 3D models via the fiducial markers. The kinematics were expressed with a coordinate system (U, V, W) developed around the geometry of each facet’s articular surface [3]. U-V was a best-fit plane to the surface. U pointed superiorly, V was directed anteromedially, and W was perpendicular to the plane. U- and V-translations corresponded to an L3 facet articulating in the plane of the opposing facet, while facet separation was indicated by a W-translation. A linear mixed-effects regression model tested for differences in translational range of motion by condition for each test. The right and left joint data were combined according to symmetry, and the significance level was adjusted (P < .0033) to account for multiple comparisons. Results: After SD, the facets exhibited significantly more translation in the U-direction (T_U ) during: (1) flexion-extension and (2) the multi-axis test combining flexion with contralateral bending followed by extension with ipsilateral bending. In flexion-extension, T_U was significantly greater than what was measured in the intact (99.67% confidence interval (CI) = 0.6-2.0 mm) and PD (CI = 0.2 -1.1 mm) conditions. For the multi-axis test, T_U was significantly different between the SD and intact conditions (CI = 0.5-2.2 mm). In general, PD did not increase the facets’ translations. The one exception was in flexion-extension, where there was a statistically significant increase in T_U from intact (CI = 0.0 -1.3 mm). Conclusion: Both procedures resulted in greater facet articulation in the superoinferior direction. The most significant increases occurred after SD. This study provides new data on the biomechanical effects of microdiscectomy and may have clinical implications for the postoperative health of the facet joints.

References

1. Dunlop RB, Adams MA, Hutton WC. Disc space narrowing and the lumbar facet joints. The Journal of Bone and Joint Surgery British. 1984; 66: 706-710.

2. Panjabi MM, Krag MH, Chung TQ. Effects of disc injury on mechanical behavior of the lumbar spine. Spine. 1984; 9: 707-713.

3. Jegapragasan M, Cook DJ, Gladowski DA, et al. Characterization of articulation of the lumbar facets in the cadaveric spine using a facet-based coordinate system. The Spine Journal. 2011; 11: 340-346.

P037 - A Comparison Of Sagittal Spinopelvic (Sp) Parameters In American And Korean Populations

Woojin Cho¹, Sandip P. Tarpada², Matthew T. Morris²

¹Department of Orthopaedic Surgery, Albert Einstein College of Medicine / Montefiore Medical Center, Bronx, NY - United States ²Albert Einstein College of Medicine, Bronx, NY - United States

Introduction: Recent literature has found variation in normal spinopelvic parameters among various isolated populations. Knowledge of this variation in normal anatomy is critical in assessing and managing disease of the axial skeleton. Here we present a retrospective chart review of SP parameters between 2 urban populations from America and Korea. Methods: Data from healthy American and Korean subjects from two major urban institutions were retrospectively obtained. Patient ethnicity was obtained in accordance with both institutional review boards. The following measurements were made from standing PA and lateral films from both populations, and compared using two sample T-tests: pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), T1-Pelvic angle (TPA), sagittal balance (SB), angle of maximal thoracic kyphosis, and coronal balance (CB). Results: A total of 265 patients (55 American, 210 Korean) were included. Mean PI was significantly larger in Americans (60.5 ± 15.9° vs. 44.2 ± 11.8°; p < 0.001), as were mean SS (39.6 ± 20.1 vs. 30.3 ± 8.1; p = 0.002), and mean max thoracic kyphosis (50.9 ± 13.4 vs. 30.44 ± 9.7; p < 0.001). PT was found to be significantly greater among Koreans (14.0 ± 8.8 vs. 9.8 ± 10.4; p = 0.008). TPA, SB and CB did not differ between the 2 groups (p = 0.24, 0.15, and 0.2, respectively). Conclusion: Pelvic incidence, pelvic tilt, sacral slope, and maximal thoracic kyphosis differ significantly in American and Korean patients. Accurate assessment of SP parameters is crucial to achieving surgical success.

P038 - Biomechanics Of The Relationship Between Adjacent Segment Disease (ASD) After Lumbar Arthrodesis And Sagittal Imbalance: A Finite Element Study

Koji Matsumoto¹, Anoli Shah², Sushil Sudershan², Anand Agarwal², Vijay K. Goel²

¹Nihon University School of Medicine, Tokyo - Japan ²Engineering Center for Orthopedic Research Excellence (E-CORE), University of Toledo, Toledo - United States

Introduction: Posterior lumbar fusion with pedicle screw fixation has been widely used, making adjacent segment disease (ASD) unavoidable following the spinal fusion. Some authors have shown significant correlation between spino-pelvic parameters and the occurrence of ASD after lumbar fixation. Patients with sagittal imbalance recruit compensatory mechanisms such as pelvic retroversion and reduction of thoracic kyphosis (TK) to maintain an erect posture. Biomechanics of the relationship between ASD after lumbar arthrodesis and sagittal imbalance remain unclear. The purposes of this study are to reveal the biomechanics of relationship between ASD (proximal and distal junctions) and different sagittal balance following lumbar arthrodesis using finite element (FE) analyses. Material and Methods: A validated finite element model from T1 to femur without rib cage was used. The sagittal vertical axis (SVA), lumbar lordosis (LL), TK, pelvic incidence (PI), pelvic tilt (PT) and sacral slope (SS) were modified to develop three different sagittally balanced models, simulating different compensate-mechanisms. These are A) Normal (Balanced: SVA = 0 mm, LL = 50°, TK = 25°, PI = 45°, PT = 10°, SS = 35°); B) Flat back (Balanced with compensatory mechanism: SVA = 50 mm, LL = 20°, TK = 20°, PI = 45°, PT = 30°, SS = 15°); C) Hyper kyphotic (Imbalance: SVA = 150 mm, LL = −5°, TK = 25°, PI = 45°, PT = 40°, SS = 5°). A posterior rigid pedicle screw fixation system was simulated across L2-L5. The model was fixed at the distal femurs and 2 Nm moments were applied at T1 to simulate flexion (FLEX), extension (EXT), right bending (RB), left bending (LB), right rotation (RR) and left rotation (LR) in intact and instrumented models. The von Mises stress on the proximal vertebra (L1) and distal vertebra (S1) as an indicator of proximal junction kyphosis (PJK) & distal junction kyphosis (DJK) were calculated and compared. Results: The maximum von Mises stress at the proximal vertebra increased by up to 143% (The average of all motions: 74.9%) in flat back model and 18% (6.0%) in kyphotic model compared to the normal model. The maximum von Mises stress at the distal vertebra increased by up to 196% (The average of all motions: 49.5%) in flat back model and 527% (141.8%) in kyphotic model compared to the normal model. In the instrumented flat back, the maximum von Mises stresses at the proximal vertebra and distal vertebra were by up to 11.7 MPa (The average of all motions: 7.5 MPa) and 15.4 MPa (9.1 MPa). In instrumented kyphotic model, the maximum von Mises stresses at the proximal vertebra and distal vertebra were by up to 5.6 MPa (The average of all motions: 4.6 MPa) and by up to 22.5 MPa (13.6 MPa). Conclusion: Our data showed that the von Mises stress on adjacent vertebra increased by up to 196% in flat back model and 527% in kyphotic model, compared to the normal model. The data suggest that careful consideration is necessary for L2-5 fixation in flat back and kyphotic models. Our data tends to suggest that kyphotic model may contribute to higher incidences of DJK than PJK. Surgeons may consider using dynamic stabilization devices in the distal region for the kyphotic patients.

P039 - Prevalence Of Back Pain And Its Association With Body Mass Index And Schoolbag Weight In Teenagers On A Bogotá School From 2016-2017

Fernando Alvarado¹, Gina Velasquez², Maria Constanza Bedoya³, David Meneses¹, Luis Carlos Morales³, Andres Rodriguez³, Maria Teresa Domínguez³, Maria Alejandra Garcia³

¹Department of Spine Surgery, Roosevelt Institute, Bogota - Colombia ²Department of Orthopedics, Fundacion Santa Fe de Bogota, Bogota - Colombia ³Department of orthopedics, Fundacion Santa Fe de Bogota, Bogota - Colombia

Introduction: Back pain in teenagers between 15-19 years old is the fourth leading cause of disability and school absenteeism; while in the group between 10-14 years old is located in the ninth place of disability. According to these data, we decided to evaluate the prevalence of back pain and its association with risk factors in the Colombian teenage population. Materials and Methods: A cohort of 158 teenagers between the ages of 10-18 enrolled in a school in the city of Bogotá between the sixth and tenth grades in 2016-2017. Results: The prevalence of at least one episode of back pain in the last six months was 67.1% (n = 158). The majority of teenagers presented a single point of pain in 27.8%, with the central area of the back as the most common affected region with 59.1%, while 1.3% reported having generalized back pain. Of the total studied, 46.5% belonged to 10-12 years old. 73.3% of adolescents who had a body mass index greater or equal to 25 reported back pain. Of the students who carried a schoolbag weighing more than 6 kg, 72.7% had back pain. From the teenagers who presented back pain in the last six months, 77.8% of the teenagers carrying a schoolbag whose weight was greater than 15% of the student’s body weight. Conclusions: The results show that a higher body mass index and the use of schoolbags with excessive loads are risk factors for teenagers to develop back pain. It should be noted that these data belong to only one school, so it is difficult to extrapolate to other populations. Public policies related to schoolbags weight restriction and healthy lifestyles are required in order to protect this population.

P040 - Readmissions, Complications, And Revisions For Occipitocervical And Occipitothoracic Fusion

Vikram Mehta¹, Daniel M. Sciubba², Godwin Abiola², A. Karim Ahmed², C. Rory Goodwin¹, Zachary Pennington², Nancy Abu-Bonsrah¹, Eric W. Sankey¹, John Berry-Candelario¹, Ziya L Gokaslan³, Ali Bydon², Timothy Witham², Jean-Paul Wolinsky⁴

¹Department of Neurosurgery, Duke University Medical Center, Durham - United States ²Department of Neurosurgery, The Johns Hopkins University School of Medicine, Baltimore - United States ³Department of Neurosurgery, The Warren Alpert School of Medicine of Brown University, Providence - United States ⁴Department of Neurosurgery, Northwestern University Feinberg School of Medicine, Chicago - United States

Introduction: Occipitocervical (OC) and occipitocervicothoracic (OCT) fusions are commonly performed to correct biomechanical instability. However, there is limited data on the rates of revision and post-operative outcomes following OC or OCT procedures. Material and Methods: We performed a retrospective review of patients who underwent OC or OCT fusions at our institution from August 2005-October 2014. Patients’ baseline characteristics, including age, gender, race, body mass index (BMI), co-morbidities, smoking history, presenting symptoms, and KPS score were recorded. Indication for surgery, surgical approach (i.e. anterior/posterior, or posterior alone), peri-operative and post-operative outcomes as well as last follow-up were also reviewed. Fusion was assessed via imaging and time to fusion was noted. Results: 131 patients were included in the study; 101 patients underwent OC surgeries and 30 patients underwent OCT surgeries. Indications for surgery included congenital malformations, trauma, tumor, inflammatory disease, infection or revisions. Differences in age, race and gender between the two groups were not statistically significant, however, patients in the OCT group had a significantly higher BMI than patients in the OC group (33.6 ± 4.158 and 26.23 ± 1.013, respectively, p = 0.0149). On average, patients undergoing OCT fusion had a significantly longer length of hospital stay, 16.60 ± 2.246 days, as compared to patients undergoing OC fusion, 11.16 ± 1.013 days (p = 0.0145). A significantly higher proportion of patients undergoing OC fusion were discharged with a KPS score greater than 70 compared to those undergoing OCT fusion (p = 0.0337). Between the OC and OCT groups, the frequency of patients with complications approached statistical significance (26.7% versus 43.3%, respectively, p = 0.083). However, when comparing the total number of complications between the two groups, the OCT patient group had a significantly higher proportion of complications than the patients in the OC group (0.8 ± 0.2112 and 0.404 ± 0.07 984, respectively, p = 0.0347). There were no significant associations between either type of surgery and rates of revision, hardware failure within 6 weeks, and readmission for any reason within 30 days. Conclusion: This study shows that there is no statistically significant difference between OC and OCT fusion patients with regards to readmission rate, or revision rate. However, on average, a patient undergoing OCT fusion is more likely to accrue more aggregate complications and experience a greater length of post-operative hospital stay, compared to a patient undergoing OC fusion.

P041 - Influence Of Cervical Spine Curvature On Range Of Motion Under Physiological Loading

Jobin John¹, Narayan Yoganandan², Mike Arun², Gurunathan Saravanakumar¹, Jamie Baisden²

¹Department of Engineering Design, Indian Institute of Technology Madras, Chennai - India ²Department of Neurosurgery, Medical College of Wisconsin, Wisconsin - USA

Introduction: Age, gender, and degenerative conditions affect the sagittal curvature of the cervical spine.^1,2 Pre-surgery disability and post-surgery outcomes have been correlated with sagittal curvature.^3-8 Curvature also influences the progression of disc degeneration⁹ and adjacent segment behavior after fusion¹⁰. A recent study reported that although men and women exhibit similar overall cervical curvature, women tend to have a straighter spine¹¹. Since sagittal curvature is an important clinical factor, the objective of this computational biomechanics study was to investigate the influence of the curvature variation on the range of motion (ROM) of subaxial osteoligamentous cervical column (C3-C7). Material and Methods: A finite element model of the C3-C7 column was constructed with hexahedral mesh¹². The model definitions included hard tissues (cancellous and cortical bone, endplates, articular cartilage) and soft tissues (annular fibrosus, nucleus pulposus, anterior and longitudinal ligaments, capsular ligaments, ligamentum flavum, interspinous ligaments). Further models with different curvatures were morphed from this initial model using a block-based morphing technique¹³. The initial model had a normal lordotic curvature, with a Cobb angle of 13.7° between C3 and C7 vertebrae. The ROM characteristics of this model was validated against in-house experiments of young and healthy cadaver cervical spine columns¹⁴. Models with kyphosis (Cobb angle = −1.6°) and hyper-lordosis (Cobb angle = 26.4°) were generated by morphing the initial model. Results: The baseline model responded with a total ROM of 54.57° (35.24° in flexion, 19.33° in extension). The kyphotic spine was 2.9% stiffer in flexion and 3.2% more flexible in extension, while the hyper-lordotic spine was 1.3% stiffer in flexion and 14.9% stiffer in extension. The total ROM of motion (flexion + extension) reduced by 0.7% in the kyphotic spine, while it reduced by 6.1% in the hyper-lordotic spine. Both the kyphotic and hyper-lordotic columns stiffened in flexion. In the kyphotic spine, this can be explained due to a lesser intervertebral space and corresponding reduction in disc material. On the other hand, the stiffening of the hyper-lordotic column can be attributed to the non-linear force-displacement behavior of the posterior ligaments and higher resistance due to shorter initial length of posterior ligaments¹⁵. In extension, the kyphotic spine exhibited higher ROM while hyper-lordotic column exhibited considerably lower ROM. This can be attributed to the load-bearing and motion-restricting role of the facet joints¹⁶. In the hyper-lordotic column, facet joints engaged earlier and stiffened the extension response; while in the kyphotic column, facet joints had relatively more motion before they engagement. Other variables such as the position of the head center of mass, head weight, and muscle compressive forces may also influence the ROM. This study, however, isolated their contribution and studied only the effect of curvature change in osteoligamentous column on the ROM. Conclusion: Sagittal curvature changes the range of motion in osteoligamentous cervical spine, hyper-lordosis affecting it more than kyphosis. These findings indicate the importance of spinal curvature on the ROM response, a clinically obtained metric via traditional x-rays.

Figure 1.

Finite element models of subaxial cervical spine with varying curvatures. (A) Kyphosis (B) Normal Lordosis (C) Hyperlordosis.

References

 1. Grob D, Frauenfelder H, Mannion AF. The association between cervical spine curvature and neck pain. Eur Spine J. 2007;16(5):669-678.

 2. Boyle JJW, Milne N, Singer KP. Influence of age on cervicothoracic spinal curvature: An ex vivo radiographic survey. Clin Biomech. 2002;17(5):361-367.

 3. Kato S, Nouri A, Wu D, Nori S, Tetreault L, Fehlings MG. Impact of Cervical Spine Deformity on Pre-operative Disease Severity and Post-operative Outcomes Following Fusion Surgery for Degenerative Cervical Myelopathy – Sub-Analysis of AOSpine North America and International Studies. Spine (Phila Pa 1976). June 2017:1.

 4. Katsuura A, Hukuda S, Saruhashi Y, Mori K. Kyphotic malalignment after anterior cervical fusion is one of the factors promoting the degenerative process in adjacent intervertebral levels. Eur Spine J. 2001;10(4):320-324.

 5. Iyer S, Nemani VM, Nguyen J, et al. Impact of Cervical Sagittal Alignment Parameters on Neck Disability. Spine (Phila Pa 1976). 2016;41(5):371-7.

 6. Gum JL, Glassman SD, Douglas LR, Carreon LY. Correlation between cervical spine sagittal alignment and clinical outcome after anterior cervical discectomy and fusion. Am J Orthop (Belle Mead, NJ). 2012;41(6): E81-4.

 7. Sakai K, Yoshii T, Hirai T, et al. Cervical Sagittal Imbalance Is a Predictor of Kyphotic Deformity After Laminoplasty in Cervical Spondylotic Myelopathy Patients Without Preoperative Kyphotic Alignment. Spine (Phila Pa 1976). 2015;1(4):1689-1699.

 8. Scheer JK, Tang JA, Smith JS, et al. Cervical spine alignment, sagittal deformity, and clinical implications. J Neurosurg Spine. 2013;19(2):141-159.

 9. Okada E, Matsumoto M, Ichihara D, et al. Aging of the cervical spine in healthy volunteers: a 10-year longitudinal magnetic resonance imaging study. Spine (Phila Pa 1976). 2009;34(7):706-712.

10. Hwang SH, Kayanja M, Milks RA, Benzel EC. Biomechanical comparison of adjacent segmental motion after ventral cervical fixation with varying angles of lordosis. Spine J. 2007;7(2):216-221.

11. Been E, Shefi S, Soudack M. Cervical lordosis: The effect of age and gender. Spine J. 2016;17(6):880-888.

12. John JD, Arun MWJ, Saravanakumar G, Yoganandan N. Cervical spine finite element model with anatomically accurate asymmetric intervertebral discs. In: Summer Biomechanics, Bioengineering, and Biotransport Conference.; 2017.

13. John JD, Arun MWJ, Yoganandan N, Saravanakumar G, Kurpad SN. Mapping block-based morphing for subject-specific spine finite element models. Biomed Sci Instrum. 2017;53.

14. Wheeldon JA, Pintar FA, Knowles S, Yoganandan N. Experimental flexion/extension data corridors for validation of finite element models of the young, normal cervical spine. J Biomech. 2006;39(2):375-380.

15. Wang K, Deng Z, Wang H, Li Z, Zhan H, Niu W. Influence of variations in stiffness of cervical ligaments on C5-C6 segment. J Mech Behav Biomed Mater. 2017;72(April):129-137.

16. Panzer MB, Cronin DS. C4-C5 segment finite element model development, validation, and load-sharing investigation. J Biomech. 2009;42(4):480-490.

P042 - Natural History Of The Aging Spine: A Cross-Sectional Analysis Of Spino-Pelvic Parameters In The Asymptomatic Population

Mark Attiah¹, Yasmine Alkhalid¹, Christine Ahn¹, Diane Villaroman¹, Bilwaj Gaonkar¹, Tianyi Niu¹, Joel Beckett¹, Luke Macyszyn¹

¹Department of Neurosurgery, University of California, Los Angeles - United States

Introduction: The treatment of spinal disorders over the past few decades has increasingly focused on spinal alignment in the sagittal plane and the relationship of the sagittal profile to the pelvis. An unbalanced spine has been shown to lead to increased pain, disability, and a reduced patient reported quality of life. Nonetheless, surgical correction goals have been predominately extracted from patients with spinal disease/deformity. Hence, we performed a retrospective, cross-sectional analysis in a healthy population to quantify the natural history of spinal alignment with age. Material and Methods: Sagittal, full-length radiographs encompassing the cervical, thoracic and lumbar spine of 211 asymptomatic patients were evaluated (age range 18 to 80). The following parameters and relationships were measured or calculated: Cervical lordosis (CL), thoracic kyphosis (TK), lumbar lordosis (LL), pelvic incidence (PI), truncal inclination (TI), sagittal vertical axis (SVA), cervical sagittal vertical axis (cSVA), and T1 slope, T1 slope/CL, TK/LL, and LL-PI. Patients were subdivided by age in decades. Regression analysis was subsequently performed to study relationship between each consecutive age group and the listed parameters. Results: Cervical lordosis (r = 0.6), thoracic kyphosis (r = 0.8), and truncal inclination (r = 0.36), SVA (r = 0.88), cSVA (r = 0.5), and T1 slope (r = 0.77) all increase with age. T1/CL remains stable over all decades (r = 0.01). The ratio between TK and LL also remains stable until the 7th decade of life (r = 0.8). LL is greater than PI but slowly declines until the 5th decade, where it becomes less than PI (r = 0.95). SVA remains below 5 cm until the 7th decade of life. Before and after age 50, the average LL -55.89, and -48.53 respectively. Similarly, before and after age 50, the average TK was 27.16, and 31.73 respectively. Finally, before and after age 50, the average CL was -10.99, and -15.53 respectively. Conclusion: This study shows the natural history of spino-pelvic parameters and their relationship with age in a healthy population and provides important insight for surgical correction guidelines. Given its stability over different age groups, the ratio of T1 slope/CL is an important relationship to maintain/target when performing cervical spine surgery, especially fusion across the cervicothoracic junction. Likewise, the harmonious relationship between TK and LL should be considered when correcting sagittal imbalance. Finally, in support of previous literature, this cross-sectional study demonstrates the proposed ideal spinal balance of LL = PI + 10 and SVA < 5 cm are appropriate targets, especially for patients aged 50 and younger.

P043 - An In Vitro Biomechanical Analysis Of Contralateral Sacroiliac Joint Motion Following Unilateral Sacroiliac Reconstruction

Woojin Cho¹, Wenhai Wang²

¹Albert Einstein College of Medicine/Montefiore Medical Center, New York - United States ²Musculoskeletal Education and Research Center (MERC) a division of Globus Medical Inc., Audubon - United States

Introduction: Sacroiliac (SI) joint disorders represent a challenging diagnosis to a subpopulation of patients experiencing debilitating focal pain. SI screw fixation has been evaluated in a limited context; however, the role of unilateral fixation remains unknown. Lumbopelvic reconstructions applied unilaterally to the pelvis have shown contralateral SI joint hypermobility. Material and Methods: Seven human lumbopelvic spines were used in this study. The spines were affixed to a six-degrees-of-freedom testing apparatus, and pure unconstrained bending moments of 8, m were applied in physiological planes. Plexiglas markers were secured to L3, L4, L5, sacrum, the left iliac crest, and right iliac crest via bone screws to track motion. An SI joint system (Globus Medical, Inc., Audubon, Pennsylvania, United States) was used for all lateral iliosacral screws (Slotted SIJ screws, 30-45 mm in length, 10 mm diameter). Initially, both left-sided iliosacral ligaments and posterior ligaments were cut, by insertion of the scalpel into the entire junction of the posterior iliac crest and sacrum from its most cephalad to its most caudal border, transecting all transverse and oblique attachments down to the joint. Subsequently, the surgical reconstruction groups were: (1) two left-side SI screws, and (2) three left-side SI screws. Each group was tested with and without pedicle screws and rods at L5–S1. Results: There were no statistical differences between left- and right-side SI joint motion following unilateral instrumentation of either two or three SI screws. The posterior ligamentous injury and the addition of pedicle rods at L5–S1 provided the highest increases in motion across both joints; however, there were no differences specific to the contralateral side in any loading mode. All loading modes had similar trends, exhibiting very small amounts of motion (flexion-extension∼1°; lateral bending∼0.2°; Axial Rotation∼0.5°). Conclusions: Preferential treatment of unilateral SI joint dysfunction appears to be biomechanically equivalent to a bilateral treatment, in terms of short-term, post-operative stability. Therefore, a one-sided approach is preferred in these cases.

P044 - How Important is the Biological Fusion in a Long Lumbopelvic Spinal Fixation? – An In-Silico Biomechanics Analysis

Woojin Cho¹, Wenhai Wang², Brandon Bucklen²

¹Albert Einstein College of Medicine/Montefiore Medical Center, New York - United States ²Musculoskeletal Education and Research Center (MERC) a division of Globus Medical Inc., Audubon - United States

Introduction: The failure rate of lumbopelvic fixation after long construct fusions in patients with adult spinal deformity has been reported as high as 11.9% [1]. A retrospective study found that rod fractures occurred in 5.2% of patients (8/155) with 6 mm rod diameter and the use of iliac screws was identified as a risk factor [2]. Pseudoarthrosis has been observed in 50% of patients with rod failure, necessitating revision surgery [3]. With potentially high rates of implant failure, questions remain regarding which risk factors are dominant, and if there is any relationship between implant type, spinopelvic parameters, or failure to achieve fusion. The purpose of this study is to evaluate the biomechanics of long-segment posterior reconstructions as affected by 1) biological fusion versus pseudoarthrosis, and 2) major failure versus non-failure conditions (as defined in [1]). Materials and Methods: Finite element models (T10-Pelvis) were created to match the average spinal-pelvic parameters (pelvic tilt, sacral slope, and lumbar lordosis) of two cohorts of patients reported in the literature [1], major-failure (defined as pseudoarthrosis or rod fracture above S1) and non-failure groups. Vertebral segments were modeled as three-dimensional solid elements. Intervertebral discs, including the nucleus and annulus, were structured as hyperelastic materials. The sacroiliac joint was modeled as articular cartilage contacts surrounded by six types of strong ligaments depicted as spring elements. Pedicle screws with 5.5 mm diameters were modeled as titanium cylinders. A load was applied at the T10 superior endplate to simulate gravimetric loading in a standing position. Posterior solid fusion was simulated by applying spring elements attached to the adjacent vertebrae. Overall spine stiffness was increased by 200% for “solid” fused spines and by 100% for pseudoarthrosis. Results: Upper body weight acting on the long instrumented spine created bending moments of 17.3 Nm and 20.7 Nm in the non-failure and major-failure groups, respectively. Loading resulted in 14 mm translation and 4.9 degree rotation for the major-failure group — 18% and 14% higher than the non-failure group. Solid posterior fusion dramatically increased the stiffness of the spine, decreasing translation by 42% and 41% and rotation by 35% and 31% in the non-failure and major-failure groups, respectively. Higher stress was observed in the rod at the L1-L2 and L4-L5 levels in both groups. Rod stress was 20% higher in the major failure group than in the non-failure group. Solid posterior fusion alleviated rod stress in the lower lumber region. Conversely, simulated pseudoarthrosis produced stress patterns similar to those observed in the construct-only spine, regardless of spinopelvic parameters. Conclusion: The spinopelvic parameters of the major-failure group produced increased gravity load, resulting in increased motion, stress, and strain compared to the non-failure group. Simulated “solid” fusion in the lumbar region further increased lumbar rigidity, decreasing range of motion and stress/strain, while shifting stress concentrations to the proximal treated levels. In total, the results emphasize both the importance of sagittal alignment and the necessity of biological fusion to reduce mechanical demand on screw and rod fixation in lumbopelvic fixation.

P045 - Stress Analysis In The Adjacent Vertebrae And Intervertebral Discs After Vertebroplasty And Correlation With The Volume Of Cement - A Biomechanical Study Using Finite Element Analysis

Sudhir Ganesan¹, Vignesh Jayabalan¹, Kavitha Anandan²

¹Department of Spine Surgery, Chennai - India ²Department of Biomedical Engineering, SSN College of Engineering - India

Introduction: Osteoporotic vertebral compression fractures is one of the common causes for morbidity in elderly individuals. Vertebroplasty is the commonly used technique for pain relief and early mobilisiation of these patients. However studies have shown increased rates of collapse of adjacent, non augmented vertebrae after vertebroplasty because of increased stiffness created by the cement. The purpose of the study was to assess the stress levels in the adjacent vertebrae and intervertebral discs before and after vertebroplasty and to evaluate the correlation between the stress levels and the volume of cement injected. Materials and Methods: The data in the form of CT images of the spine were acquired from a normal subject. A 3D model of T11 to L3 region was generated using MIMICS software and 3 MATIC, after performing volume and surface rendering techniques. A force of 600 N was applied to the vertebrae for varying conditions of BMD, and the stress levels were calculated individually. Then, three fractures were induced at L1 and 3D models were generated. The stress levels on the fractured spine for forces of 600 N, 1200 N and 1800 N were assessed. To assess the conditions after vertebroplasty, PMMA cement was injected in the fractured spine using Boolean Operations, which helped in optimizing the cement level. The amount of cement for the three cases were 4.5631 ml, 5.5771 ml and 6.5849 ml respectively. Results: The stress levels increased gradually from normal to osteopoenic with a maximum in the osteoporotic cases. The stress levels were more in the L1-2 disc than in the T12-L1 disc and the stress levels were significantly high in both the disc levels in osteoporotic cases. On anlaysing the stress levels after fracture, highest stress developed in the L2, and the lowest in the T12 vertebra. After vertebroplasty, there was a significant reduction in the stress levels in all the vertebrae and discs. It was found that the stress levels in T12 vertebra was higher whereas in L2 it was lower than normal cases. Similarly, the stress levels in T12-L1 disc was higher and L1-2 disc was lower compared to normal cases signifying an increased stress in T12 vertebra and T12-L1 disc after injection of cement. Also, increased volume of cement injected increased the stress at all levels significantly. Conclusion: Vertebroplasty for osteoporotic fractures can increase the stress levels in adjacent vertebrae and discs more in the proximal than distal levels owing to the stiffness of the cement injected. Also, the stress levels are directly proportional to the volume of cement injected. Hence optimal range of cement injection could prevent adjacent level fractures.

P046 - Pedicle Screw reviPsion Pull-Out Strength – Does the Screw Thread Design Matter? An Ex Vivo Biomechanical Study

Wei Ren Daniel Seng¹, Shiblee S Siddiqui¹, Yoong Leong Jacob Oh¹

¹Department of Orthopaedic Surgery, Tan Tock Seng Hospital, Singapore - Singapore

Introduction: There is growing interest in optimising pedicle screw pull-out strength. While primary pull-out strength has been heavily studied, little is known about revision pull-out strength of different pedicle screws. Our study aims to evaluate the difference in primary and revision pull-out strength using pedicle screws of different thread designs. Material and Methods: The pull-out strengths of three different pedicle screw designs (single-thread, mixed-thread, dual-thread) were tested in standardised polyurethane foam in three sequences. Sequence 1: A 6.5 mm screw was inserted into the foam block and the primary pull-out strength measured. Sequence 2: A 6.5 mm screw was inserted, removed, and then reinserted into the same foam block. The revision pull-out strength was then measured. Sequence 3: A 6.5 mm screw was inserted, removed and a 7.5 mm screw of the same thread design was reinserted. The revision pull-out strength was then measured. Results: The primary pull-out strength was similar across screw designs, although dual-thread screws showed higher primary pull-out strength (2628.80 N) compared to single-thread screws (2184.43 N, p < 0.05). For revision pull-out strength, the mixed-thread screws had significant reduction in revision pull-out strength of 18.6% (1890.15 N, p = 0.0173). Revision with a larger diameter screw improved the pull-out strength back to baseline. Single and dual-thread screws showed no significant reduction in revision pull-out strength. Conclusion: Mixed-thread screws are more costly than single and dual thread screws and may not offer any advantage for primary pull-out strength. In cases where screws have to be revised, the revision pull-out strength drops by 18.6% compared to other screw designs. Surgeons should be cautioned and consider using larger diameter mixed-thread pedicle screws in a revision setting if appropriate.

P047 - The Protective Role Of Interspinous Process Device On The Adjacent Disc To A Rigid Instrumented Level- A Finite Element Analysis

Haoju Lo¹

¹Department of Orthopedic, Jen-Ai Hospital, Dali Branch, Taichung - Taiwan, Province of China

Introduction: The elimination of motion and disc stress produced by spinal fusion may have potential consequences beyond the index level overloading the spinal motion segments and leading to the appearance of degenerative changes. So the “topping-off” technique is a new concept instructing dynamic fixation such as interspinous process device (IPD) for the purpose of avoiding adjacent segment disease (ASD) proximal to the fusion construct. Materials and Methods: The study simulated spinal fusion in L4-L5, fusion combined DIAM in L3-L4. The ROM and maximum von Miss stresses were analyzed in flexion, extension, lateral bending, and torsion in response to hybrid method, compared to intact model and fusion model. Results: The investigation revealed that decreased ROM, intradiscal stress in implanted level but a considerable increase in stresses at more upper level (L2-L3) during flexion and extension in hybrid model, comparing with the fusion model. Conclusions: The raise of intradiscal pressure at the adjacent segment to a rigid fusion segment can be reduced when the rigid construct is augmented with an interspinous process device. However, the burden of stress over total spinal segments was still the same, the stress and ROM were just shift to supraadjacent levels.

Deformity-Cervical

P048 - A Rare Case Report Of Progressive Dropped Head Syndrome Managed With C7 Pedicle Subtraction Osteotomy

Srinath P¹, Ravi V²

¹Department of Orthopedics, Apollo Hospitals, Chennai - India ²Department of Spine Surgery, Apollo Hospitals, Chennai - India

Introduction: Dropped head syndrome (DHS) is a relatively rare condition. While surgery seems to be an obvious therapeutic option, there is a paucity of information on surgical intervention with no clear consensus on an optimal approach or timing. The treatment of cervical progressive flexion deformity in ankylosing spondylitis presents a challenging problem that is traditionally managed by a corrective cervicothoracic osteotomy. We report an approach that involves pedicle subtraction osteotomy at the area of maximal spinal curvature and deformity correction with stabilization of occipito-cervico-thoracic area. Materials and Methods: This is a 37 years old gentleman who had an old history of RTA(Road Traffic Accident) in 1999 had undergone craniotomy and evacuation of SDH(Sub Dural Hematoma) and C2-C3 fixation (Posterior – Hartshell Rectangle) in 2000 now has complaints of gradual progressive neck deformity that left him unable to see ahead and caused him to experience difficulty eating, drinking, not able to drive. Patient has a recent history of trauma 6 months ago aggravated the presenting condition and was diagnosed with Ankylosing Spondylosis. On examination, he exhibited a flexion deformity of the cervical spine, which was maximum at C7; this was confirmed on imaging studies. During his admission traction was initially given but no improvement was noticed and hence terminated after 48hours. Later he was undertaken for pedicle subtraction osteotomy C7, deformity correction and stabilization of occipito-cervico-thoracic spine. Correction of the deformity was achieved. Results: Peroperatively we achieved 35 degrees of correction. Mild forward bending is retained so that patient will be able to walk and get down stairs without problem. Post operatively there were no complications and achieved good fusion and improved functional status of patient. Patient is followed for 3 years showing good fusion and maintenance of correction. Conclusion: A pedicle subtraction osteotomy performed at the level of maximum spinal curvature in ankylosing spondylitis combined with posterior stabilization enables complete correction of severe flexion deformity in a single procedure. Retaining some amount of flexion is important so that patient will be able to walk and get down stairs without problem.

P049 - Influence Of Atlantoaxial Fusion On Sagittal Alignment Of Occipitocervical And Subaxial Spines In Os Odontoideum With Reducible Atlantoaxial Instability

Jong-Beom Park¹, Eric Taejin Park², Byung-Wan Choi³, Jong-Won Kang⁴, Han Chang⁵

¹Department of Orthopaedic Surgery, Uijongbu St.Mary’s Hospital, The Catholic University of Korea, Seoul - Korea, Republic ²College of Art and Science, Emory University, Atlanta - United States ³Department of Orthopedic Surgery, Haeundae Paik Hospital, Inje University, Busan - Korea, Republic ⁴Department of Orthopedic Surgery, Daejeon Sun Hospital, Daejeon - Korea, Republic ⁵Department of Orthopedic Surgery, Busan Korea Hospital, Busan - Korea, Republic

Introduction: In our experience, sagittal malalignment, such as kyphosis or loss of lordosis, occurs at occipitocervical and subaxial spines following atlantoaxial fusion. However, little information is available about the effect of C1-C2 angle on sagittal malalignment of C0-C1 and C2–C7. We hypothesized that the severity of the sagittal malalignment of C0-C1 and C2–C7 increases with the increase in the C1-C2 angle. Material and Methods: We retrospectively reviewed 21 patients (10 females and 11 males) who achieved solid atlantoaxial fusion for reducible atlantoaxial instability (AAI) secondary to Os odontoideum. Nonunion cases were excluded from this study. The mean age at the time of surgery was 42.8 (range, 5–73) years, and the mean follow-up duration was 4.9 (range, 2–12) years. Eleven patients with anterior AAI underwent posterior sublaminar wiring alone, and 10 patients with combined AAI underwent posterior sublaminar wiring and transarticular screw fixation. Radiographic parameters were measured before surgery and at the final follow-up. C0-C1, C1-C2, and C2–C7 angles were measured on neutral lateral radiographs. Ranges of motion (ROMs) at C0-C1, C1-C2, and C2–C7 during flexion and extension were measured on lateral radiographs. Patients were divided into two groups according to the final C1-C2 angle. The final C1-C2 angle was ≥22° in group A (N = 11) and <22° in group B (N = 11). Differences in radiographic parameters between the groups were evaluated. Results: At the final follow-up, the C1-C2 angle was increased, but this increase was not statistically significant (18° compared with 22°, p = 0.097). In contrast, the C0-C1 (10° compared with 5°, p < 0.05) and C2-C7 (22° compared with 13°, p < 0.05) angles were significantly decreased. The final C1-C2 angle was negatively correlated with the final C0-C1 (correlation coefficient, −0.547; p < 0.05) and C2-C7 (correlation coefficient, −0.705, p < 0.01) angles. The final C0-C1 (3.8° compared with 6.2°) and C2–C7 (7.7° compared with 20°) angles were smaller in group A than in group B (both p < 0.05). After atlantoaxial fusion, ROMs at C0-C1 (17° compared with 9°, p < 0.05) and C2–C7 (39° compared with 31°, p < 0.05) were significantly decreased. Conclusion: We found that lordosis of occipitocervical and subaxial spines following atlantoaxial fusion was negatively associated with the final C1-C2 angle, along with decreased ROM. We are currently attempting to fuse the C1-C2 angle at <22° in order to decrease the likelihood of sagittal malalignment of occipitocervical and subaxial spines.

P050 - Craniofacial Miniplate Internal Fixation In Correction Of Congenital Kyphosis In An Infant With Ehlers Danlos Syndrome: Technical Report

Andrew Kobets¹, Jonathan Nakhla¹, Yaroslav Gelfand¹, Ajit Jada¹, Merritt Kinon¹, Reza Yassari¹, James Goodrich¹

¹Montefiore Medical Center, New York City - United States

Introduction: Ehler-Danlos Syndome (EDS) refers to a group of heritable connective tissue disorders a rare manifestation of which is cervical kyphosis and clinical myelopathy. EDS type VI, the kyphoscoliotic type, is associated more commonly with as severe muscular hypotonia at birth, severe and progressive kyphoscoliosis, joint hypermobility, and skin fragility with abnormal scarring. Surgical treatment is elected when conservative bracing and observation fails, and has been described extensively in the thoracolumbar spine in adolescents but never in the cervical spine in infants. Providing internal fixation for deformity correction in the infantile cervical spine is challenging due to the diminutive bony anatomy and the lack of specifically designed spinal instrumentation. We describe the first case of successful treatment and fusion of an infant with a high cervical kyphotic deformity. Material and Methods: A 15-month-old female with EDS presented with several months of regression in gross motor skills in all four extremities. On examination, the child had quite severe hypotonia in all extremities with poor truncal control, and was unable to hold the head in any position, falling either forward or backward based upon the gravitational pull. Imaging demonstrated 45 degrees of kyphosis from the C2-4 levels with severe spinal cord compression. Corrective surgery consisted of a C3 corpectomy and C2-4 anterior fusion with allograft block and anterior fixation with dual 2x2 hole craniofacial miniplates, backed up with C2-4 posterior fusion using 4 three-hole miniplates fixated to the lamina. The C2 body appeared too narrow in the coronal plane and too shallow in the sagittal plane to accept the anterior cervical plating-screw systems available for the procedure. Results: No surgical complications were observed and no postoperative bracing was used. At 20-month follow up, the patient was behind in developmental milestones in large part due to the underlying connective tissue disease but had demonstrated marked neurological improvement. She was able to combat-crawl with great ease and was able to pull herself up into a standing position. Radiographs demonstrated solid fusion both anteriorly and posteriorly with maintenance of correction. Conclusion: The use of craniofacial miniplates may be useful as an adjunct or salvage technique in pediatric patients needing cervical spine fusion in whom very young age or anatomic factors limit the use of conventional spinal hardware or a halo vest. While cases of thoracolumbar spinal fusion exist in older patients, we present the first report of a successful cervical fusion in an infant with EDS. Fixation in the infantile spine may be challenging due to the diminutive size of the bony anatomy and the lack of spinal instrumentation designed specifically for its fixation. Addition, surgery in EDS patients carries novel risks such as a high propensity for vascular injury, greater intra-operative bleeding secondary to small vessel fragility, and ligamentous laxity that allows for correction beyond which muscular, neural, and vascular structures can tolerate. However, these complications occur rarely with meticulous surgical technique, and solid fusion is noted at follow-up in the overwhleming majority of these patients.

P051 - Clinico-Radiological Features Of 26 Patients With Congenital Atlantoaxial Dislocation And New Grading System

Olga Pavlova¹, Sergey Ryabykh¹, Alexander Gubin¹, Alexander Burcev¹

¹Ilizarov Center, Kurgan - Russian Federation

Summary of background data: Atlantoaxial dislocations (AAD) due to congenital anomalies of the craniovertebral junction often accompanied by myelopathy, violations of neck movements and torticollis. Objectives of the study: Determine the clinical and radiological features of congenital AAD and choose the most optimal grading system for assessing the severity of the AAD. Materials and methods: We analyzed 26 patients with congenital AAD, treated in the Ilizarov Center from 2012 to 2017. An assessment was made for certain clinical and radiological criteria and scales. Results: There were 6 patients (23.1%) with nonsyndromic AAD, 11 patients (42.3%) with AAD and Klippel-Feil syndrome (KFS) and 9 patients with syndromic AAD (34.6%). Patients with nonsyndromic AAD had local pain syndrome VAS 4.2 in average (from 0 to 5, mean 2.5), accompanied by torticollis and restriction of neck movements, and three had myelopathy (50%). In patients with AAD and KFS local symptoms prevailed: limitation of neck movements (100%), torticollis (100%) and neck pain (72.7%) VAS 2.4 in average (from 0 to 6, mean 2.0), three had myelopathy (27.3%). All patients with syndromic AAD had the symptoms of myelopathy (100%) and 8 of them had local pain syndrome (88.8%), VAS 2.3 in average (from 0 to 5, mean 1 point). Odontoid anomalies was presented in 15 patients (57.7%) and measurement of ADI, PADI and VAAI was not possible in this group of patients. Myelopathy occurred in 15 patients (57.7%). Torticollis and restriction of neck took place in 15 patients (57,7%), neck pain took place in 21 patients (80,8%), VAS 2.3 points in average (from 0 to 6, mean 1). In all patients it was possible to determine the displacement of C1facets in different planes. Based on the displacement value of facets C1, the degree of dislocation was evaluated in each patient and these data were compared with clinical data. Most often myelopathy and stenosis of the vertebral canal at the C1 level appeared in patients who had a C1 grade II-III dislocation in the sagittal and frontal plane. The most pronounced local symptoms (restriction of neck movements, neck pain and torticollis) were in patients with a grade II-III C1 dislocation in the axial plane. Conclusions: Myelopathy often occurs in patients with syndromic AAD and such patients require early aggressive surgical treatment, whereas patients with AAD and KFS and non-syndromic AAD often show local symptoms. The existing AAD classifications are not always suitable for patients with congenital AAD, as in our group of patients they are often have odontoid abnormalities. In these cases it is convenient to look on the C1 facets displacement in different planes. The new classification of the AAD, based on the CT-evaluation of the C1 facets displacement in the sagittal, frontal and axial planes is convenient in practice.

P052 - Profile Of And Correlation Between Objective And Subjective Assessment Of Hand Function Following Surgery For Hirayama Disease: A Cohort Study

Yilong Zhang¹, Yu Sun¹

¹Peking University Third Hospital, Beijing - China

Introduction: Hirayama disease is also known as “juvenile muscular atrophy of the unilateral upper extremity”. Patients with Hirayama disease experience arm and hand dysfunction limiting participation in functional activities. Although, conservative management of Hirayama disease by using cervical collars was the most widely accepted treatment strategy, in recent years, it has been well established that surgery is an alternative treatment for severe Hirayama disease or cases in which cervical collars are not tolerated, offering similar or superior results to conservative cervical collar therapy. But surgical indication is still controversial. So the profile of Hirayama patients after surgery is meaningful. The purpose of this research was to investigate the profile of and correlation between objective and subjective assessment of hand function following surgery for Hirayama disease. Material and Methods: We enrolled 20 patients treated with simple anterior internal fixation surgery by the same group of surgeon from Nov. 2006 to Sep. 2014 (20 males and mean age 18.75 years old). Among them, 9 patients were evaluated consecutively before treatment, 3 months after treatment, 1 year after treatment and more than 2 years after treatment. Hand function and skills were evaluated by Jebsen Taylor Test of Hand Function (JTHFT) and the Odom criteria were used to evaluate the subjective assessment. Results: 1. Hirayama patients showed varying degrees of dysfunction in all items of JTHFT in both dominant hand and non-dominant hand.2. The total time of JTHFT was decreased from 72.3 s to 60.2 s (P less than 0.01).3. 20 patients’ grade of Odom criteria was 2.23, among them the consecutive follow-up patients, the mean grade of Odom criteria was 2.56 at 3-month follow-up, 2.67 at 1 year follow-up and 2.30 at the last follow-up. 4. Odom criteria showed a significant correlation with one item of JTHFT at 3 months after surgery, with decrease of total time at 1 year after surgery and the final follow-up. Conclusion: Compared with the normal population, patients with Hirayama disease clearly have worse upper extremity function prior to surgery. Each domain of the JTHFT improved to some degree after surgery and patients were satisfied with the operation curative effect. At the early stage of recovery, patients paid more attention to the improvement of muscle strength and with the extent of recovery, patients cared more about the overall improvement of upper extremity function.

P053 - Posterior Interarticular Fusion, Reduction And Fixation Technique For Treatment Of Basilar Invagination With Atlantoaxial Dislocation

Zan Chen¹, Fengzeng Jian¹

¹Department of Neurosurgery, Xuanwu Hospital, Capital Medical University, Beijing - China

Introduction: Basilar invagination (BI) with atlantoaxial dislocation (AAD) is a complex craniocervial junction anomaly. The posterior and upward shift of the odontoid process leads to compression of the medulla and the spinal cord, which causes neurological dysfunction. Posterior reduction has a lower rate of complication than that of transoral approach, but the complete restoration rate is not satisfied, especially the restoration of the vertical dislocation. We considered that lacking of proper rigid intrarticular implants is the key factor for the failure of unsuccessful restoration. As there’s not any product of spacer in our area, we tried placing specially selected cages (which usually placed intervertebral) interarticularlly as spacers to restore the vertebral dislocation, followed by reduction and fixation to restore the horizontal dislocation. This study was to to quantify the improvement of clinical and radiological indices using this procedure, and to analyze the safety of the technique. Material and Methods: A case series study (Dec 2016-Feb 2016). Using this technique, reduction was achieved in 30 patient with basilar invagination and atlantoaxial dislocation (mean, 45.6 ± 12.5 years of age). All patients suffered from different degrees of quadriparesis or numbness of limbs, two of them had dysphagia. Four of them had underwent unsuccessful posterior reduction procedure before and suffered from aggravated symptoms. The mean preoperative distance was 7.5 ± 3.5 mm above the Chamberlain line, and the mean ADI was 13.6 ± 5.6 mm. The mean JOA score preoperative was 7.5 ± 2.5. After releasing the facet joint, specially selected polyetheretherketone cage was placed, reduction and fixation was then achieved. As there’s high rate of anomalous vertebral arteries in CVJ anomalies, especially for occipitalized C1 cases which are very common in BI with AAD. 3D CTA was performed in most cases. We studied the 3D course of the vertebral arteries carefully before operation, try to design proper strategy of intraoperative manipulation to release the vertebral arteries, to make it enough space for placing the cages and also avoid injury to vertebral arteries. Results: In 4 cases, we chose cervical cage usually used in anterior cervical approach, of 14 mm in width,12 mm in length and 6-7 mm in height. In 26 cases, we chose lumber cage usually used in posterior lumber approach, of 10 mm in width, 23 mm in length and 7-12 mm in height. Nondominant vertebral arteries in the right side were injured completely unintentionally in 2 cases, luckily, there’s no postoperative symptoms of posterior circulation ischemia. All the patients had improvements of the JOA score (mean, 10.3 ± 2.2). The mean postoperative distance was 2.5 ± 1.2 mm below the Chamberlain line, and the mean ADI was 1.2 ± 0.5 mm postoperatively. Postoperative MRI showed release of the cervicomedullary compression. CT scan indicated no dislodgements of the cages. Conclusion: The technique of posterior Interarticular fusion with cage followed by reduction and fixation is an effective technique in reducing both BI and AAD.

P054 - The Study And Design Of Atlantoaxial Lateral Mass Intervertebral Fusion Cage For Bi-Aad Patients

Xinghua Zhao¹, Zhiyuan Xia¹, Fengzeng Jian¹, Zan Chen¹

¹Xuanwu Hospital Capital Medical University, Beijing - China

Objective: to measure the geometry of the lateral joint of BI-AAD patients and design the loosening tool and the corresponding intervertebral fusion cage. Methods: 28 cases of BI-AAD patients were collected from our hospital and Cooperative hospital between 2015-11 to 2016-04 as experimental group, 25 cases of normal people as control group. Collected the clinical data and the cranio cervical thin CT scan data, and measured the diameter length of lateral atlantoaxial joint in coronal section and vertical section, atlantodental interval, sagittal joint inclination, Chamberlain line, and the craniocervical tilt with the RadiAnt DICOM Viewer (32-bit) software. Objective to analyze and design a intervertebral fusion cage for BI-AAD patients. Results: The data show that there is no significant difference between the left and right joints in the two groups(P>0.05), therefore, we analysed data with the total number of joints which included the left and right joints.The diameter length of atlantoaxial lateral mass in coronal section and vertical section, atlantodental interval of BI-AAD patients were significantly less than control group(P < 0.001).The sagittal joint inclination, and the craniocervical tilt, atlantodental interval of BI-AAD patients were significantly bigger than control group(P < 0.001).Therefore, we designed the joint loosening tool as length 25.0 mm, width 6.0-10.0 mm, height 2.0mm; Joint facet scraper as length 25.0 mm, thickness 2.0 mm, width 6.0mm-10.0 mm, width model interval 2.0mm; The fusion cage is designed to be 8.0 mm in width, 18.0 mm or 15.0 mm in length included two types; According to the degree of basilar invagination, the fusion cage was designed as 5.0-12.0 mm in height with 1 mm as the interval, and there were 8 types in all. Conclusion: there are different degrees of deformity in the lateral atlantoaxial joint of BI-AAD patients. Based on the morphology of lateral joint deformity, a atlantoaxial lateral mass intervertebral fusion cage, Joint facet scraper and joint loosening tool were designed.

Keywords: basilar invagination combined with atlantoaxial dislocation; atlantoaxial lateral joints; geometric shape; joint loosening tool; BI-AAD; fusion cage; design

P055 - Hybrid Fixations For Atlantioaxial Dislocation Or Instability

Hao Zhang¹

¹Department of Spinal, South Medical University, ShenZhen - China

Introduction: Most of atlantoaxial dislocation and instability need operative treatment. Many different fixation methods can be choose, like C1-C2 pedicle screws fixation, C2 laminar screws fixation, subaxial lateral mass screws, transarticular screw, Halo-vest external fixation, which used to fixed symmetry. When atlantoaxial dislocation or instability combined with pedicle dysplasia or vertebral artery high riding, we must treat it by Hybrid fixation to get firm fixation. Material and Methods: From Feb 2010 to May 2015, 16 cases with atlantoaxial dislocation and instability were reviewed retrospective, with 10 cases of male and 6 cases of female(mean,42.3 years). 10 cases were atlantoaxial dislocation and 6 cases with instability. 11 cases with high cervical myelopathy, with JOA score 9-14, average 12.5. Results: 15cases were operated by 2 different fixations and 1 case by 4 different fixations. Hybrid fixations were used because of C2 vertebral artery high riding, C2 pedicle maldevelopment, osteoporosis. 10 cases with atlantoaxial fixation and 6cases with occipital- cervical fixations. no intraoperative vertebral artery injury and spinal cord injury were noted. noted. All patients were followed up for average30.5 months(from14 to 60months) cases. JOA scoresexhibited a significant improvement from 13 to17 (mean,15.5). No postoperative internal fixation loose and breakage were observed and atlantoaxial fusion was seen in all the cases Conclusion: Atlantoaxial dislocation or instability combined with pedicle dysplasia or vertebral artery high riding, we can have good outcome by Hybrid fixation .

P056 - Proatlas Segmentation Anomalies: Clinical Presentation, Radiological Features & Surgical Management

Natarajan Muthukumar¹

¹Department of Neurosurgery, Devadoss Multispeciality Hospital, Madurai - India

Aim: Developmental abnormalities of the craniovertebral junction (CVJ) due to defective segmentation of the Proatlas sclerotome are known as Proatlas Segmentation anomalies (PSA). In this report, clinical & radiological findings and management of nine patients with PSA are presented. Patients and Methods: Between Jan 2012 and June 2016, nine patients with PSA were encountered. Plain radiographs, thin section CT & MRI were obtained for evaluation. Surgical management varied according to the nature of the underlying pathology. Results: Four patients had cervical myelopathy. One had myelopathy with cerebellar signs, three had only neck pain & vertigo and in one patient the diagnosis was made during radiological examination after trauma. Radiologically, one patient had assimilation of anterior arch of atlas, platybasia, partial assimilation of posterior arch, basilar invagination and an accessory ossicle behind the flat clivus. The second patient had a pre-basicoccipital arch, basilar invagination, completely assimilated atlas, unilateral occipital condyle hypoplasia and Klippel-Feil anomaly. The third patient had Os Avis or dystopic os odontoideum. The fourth patient had pre-basioccipital arch and atlanto-axial subluxation. The fifth patient had severe platybasia, retroflexed odontoid compressing the cervicomedullary junction, tonsillar ectopia up to C 2 and cervical syrinx; patients six and seven had retroflexed odontoid with lateral proatlas failure, patients eight and nine had prebasioccipital arch. Six of the nine patients underwent surgery. Three patients underwent craniovertebral realignment and occipitocervical fusion. Two patients underwent Goel-Harms fusion and one patient underwent Goel-Harms fusion with distraction using spacers in the atlantoaxial joint and foramen magnum decompression. Conclusions: PSA is a rare cause of CVJ compression and/or instability. Careful CT evaluation is the prerequisite for proper diagnosis. The management of PSA is aimed at: 1. Decompressing the cervicomedullary junction if there is compression and, 2. Stabilization of the craniovertebral junction, if there is instability.

P057 - The Own Experience Of Surgical Treatment Of Patients With Mucopolysaccharidosis-Related Spinal Deformity

Poleena Ochirova¹, Sergey Ryabykh¹, Alexander Gubin¹

¹Ilizarov Center, Kurgan - Russia

Introduction: Spinal deformity in patients with mucopolysaccharidosis a problem requiring early treatment Material and Methods: We analyzed 6 cases of mucopolysaccharidosis (MPS), treated in Ilizarov Center in 2012 - 2017. There were 1 patient with MPS IH-type, 2 patients with IVA-type and 3 patients with MPS type VI. The age of the patients ranged from 6 to 26 years-old (average age - 10.3 years-old). All patients had spinal deformity with primary and/or secondary stenosis of the spinal canal. Various surgical treatments were used: 1) two staged surgery was perfomed in one patient with cervical myelopathy and scoliosis: C0-C7 decompression with occipitospondylodesis (OSD) firstly and dual growing rod construction secondly; 2) final fusion in 2 patients with scoliosis; 3) decompression at the stenosis level (cervical spine) with OSD in 3 patients with cervical myelopathy. Results: Scoliosis value was from 20° to 65° Cobb, kyphosis from 15° to 80° Cobb. Four patients had vertebral stenosis and myelopathy (Frankel C). All patients had pulmonary and cardiac dysfunctions: vital capacity of the lungs was from 21% to 50% and abnormal ECG. Imbalance in the frontal and sagittal planes was present in 60% of patients. Through surgical treatment correction of the kyphosis was by 68% and scoliosis by 85%. In 4 (50%) patients with spinal stenosis neurologic status improved to Frankel E. Conclusion: Patients with MPS quite often have vertebral stenosis and myelopathy, in such patients with combined stenosis of the spinal canal, it is necessary to combine decompression and fusion.

P057 - Surgical Treatment For Spondilotic Myelopathy Present In Klippel-Feil Syndrome: A Case Report

Victoria Vargas¹, Maria Constanza Bedoya¹, Camilo Velez¹, Fernando Alvarado², Andres Rodriguez¹, Maria Alejandra Garcia¹, Maria Teresa Domínguez¹

¹Department of orthopedics, Fundacion Santa Fe de Bogota, Bogota - Colombia ²Department of Spine Surgery, Roosevelt Institute, Bogotá - Colombia

Introduction: Klippel-Feil is a syndrome characterized by anomalous fusion of the cervical vertebrae, due to a failure in mesoderm segmentation. From 1912 a triad is described for its diagnosis: low implantation of the hair in the nape, short neck and diminished movement arcs, however, less than half of the patients present it. Furthermore, it is related to many other malformations or complications, such as spondylotic myelopathy. It is reported that 22% of patients with this syndrome have neurological symptoms and 6% require surgical treatment. Materials and Methods: A 44-year-old patient with Klippel-Feil syndrome accompanied by spondylotic myelopathy, who remained asymptomatic 4 years, she presents with progressive pain, paresthesia, paresis of upper limbs and altered bicipital reflexes. Diagnostic images show complete fusion of C2 to C3 that was found in butterfly like C5-C6. In addition, commitment is reported in the breadth of the conjugation foramina. Results: The patient underwent decompression and anterior cervical arthrodesis because of the symptoms and electrophysiological alterations. The surgical treatment for this case was satisfactory, the canal was decompressed and the symptoms improved considerably, the patient is still in follow-up. Conclusions: It is important to emphasize that this disease is commonly diagnosed during childhood and needs constant tracked to evaluate the risk of developing symptoms in contrast to a rigid segment.

Keywords: klippel-feil syndrome, cervical fusion, spondylotic myelopathy

P059 - The Cervical Spine Realignment After Kyphosis Correction Of The Chronic Atlantoaxial Anterior Dislocation

Kai Cao¹, Zhimin Pan², Pingguo Duan¹, Yiwei Chen¹, Junlong Zhong¹

¹Orthopedics Department, The First Affiliated Hospital of Nanchang University, Nanchang - China ²Department of Neurosurgery, Spine and Spinal Cord Institute, Yonsei University College of Medicine, Seoul - Korea, Republic

Introduction: Old atlantoaxial anterior dislocation not only brings about myelopathy, but dislocation-related kyphosis also results in cervical malalignment which permanently influences patients neck function and HRQoL. Few study reported the association of realignment of cervical spine and improvement of HRQoL after kyphosis correction in this scenario. This study is to investigate the effect of kyphosis correction on realign the cervical spine as well as the significant independent factors associated with the improvement of HRQoL. Material and Methods: Consecutive old atlantoaxial anterior dislocation-related kyphosis patients underwent C1-2 reduction and fusion were included in this cohort. MRI, CT and upright X-ray of spine were taken pre- and postoperatively. Cervical alignment parameters including C0 -1, C1-2, C0-2, C2-7 cobb angle, C1-7 sagittal vertical axis (SVA), C2-7 SVA, center of gravity to C7 SVA (CG-C7 SVA), Thoracic inlet angle (TIA), Neck Tilt (NT), Cervical Tilt, Cranial Tilt and T1 Slope (T1 S) were measured. JOA, NDI and SF-12 PCS were assessed preoperatively and follow-up. Significant independent parameters associated with JOA, NDI and SF-12 PCS were analyzed by stepwise regression analysis. All patients were followed up at least 2 years. Results: Total 21 patients (9 female, 12male, age of 48.1 ± 6.3, BMI of 23.3 ± 2.9) were included in this cohort. C1-2 cobb angle, C2-7 cobb angle, TIA, Cervical Tilt, T1 S were significantly improved from -3.97 ± 16.2°, -29.16 ± 11.2°, 73.09 ± 13.3°, 30.37 ± 8.5°, 29.15 ± 8.8° preoperatively to -13.51 ± 8.1°(P = 0.04), -17.99 ± 12.0°(P = 0.02), 67.06 ± 11.6°(P = 0.004), 23.08 ± 10.3°(P = 0.04), 23.95 ± 6.9°(P = 0.003) follow-up. JOA, NDI and SF-12 PCS were significantly improved from 8.07 ± 2.5, 42.46 ± 4.8, 31.31 ± 5.1 to 14.23 ± 2.1(P < 0.001), 8.23 ± 2.9(P < 0.001), 45.92 ± 1.9(P < 0.001), respectively. Multiple linear regression indicated that the C1-2 cobb angle was identified as independent parameter significantly associated with JOA, NDI and SF-12 PCS. Conclusion: Reduction and fusion surgery can effectively correct the old atlantoaxial anterior dislocation-related kyphosis and realign the cervical spine. The restore of C1-2 cobb angle was the independent parameter to improve JOA and HRQoL.

P060 - Efficacy And Safety Of Surical Decompression And Fusion In Basilar Invagination - A Prospective Study

Anil Solanki¹

¹Department of Spine Surgery, Park Clinic, Kolkata - India

Introduction: Basilar invagination implies that the tip of odontoid is more cephalad protruding into the foramen magnum causing the compression of medulla and brainstem. Primary invagination is congenital or developmental and more common and secondary invagination is acquired mostly due to trauma. It is associated with short neck, torticollis, motor & sensory disturbances, lower cranial nerves involvement, pain, cerebellar & vestibular disturbances, syringomyelia, hydrocephalus, vertebral artery insufficiency, etc. We assessed results of posterior cervical decompression and fixation in series of such patients. Material and Methods: This is short term prospective study. Total 20 patients of various age groups (8 to 65 year) with diagnosed basilar invagination were operated for decompression and fixation using standard plate with pedicle screws and lateral mass screws or loop with wires. Fusion done using autologous bone graft taken from iliac crest. Immediate post-operative and regular 2 months follow-up examination were done both clinically and radiologically. Results: 17 patients showed improvement in their symptoms or gait with improved mJOA score, RANAWAT’s neurological class and NURICK’S functional scale. 2 patients did not show any signs of improvement. 1 patient who had severe basilar invagination with os odontoideum with kyphotic deformity expired on 3 rd postoperative day due to respiratory insufficiency. Radiologically- according to McRae, chamberlain line and Ranawat index, all 19 patients had reduction of dens below foramen magnum. Bone graft fused in all 19 patients between 6 to 8 months. One patient had wound complication and another one had asymptomatic implant loosening on follow-up. Conclusion: Excellent to good outcomes can be achieved with acceptable safety for such complex procedures. Good results depend on proper patient selection, good surgical skill, proper use of implants and post-operative care.

P061 - Neurological Mechanisms involved in Scoliosis. Systematic Review of the Literature

Roberto Diaz Orduz¹, Miguel Enrique Berbeo Calderon¹, Juan Carlos Perez Rodriguez², Stefania Prada Solano³, David Camilo Gomez Cristancho⁴

¹Neurosurgeon and Assistant Professor, Javeriana University, Department of Neurosurgery San Ignacio, University Hospital - Colombia ²Resident of Neurosurgery, Javeriana University, Department of Neurosurgery San Ignacio, University Hospital - Colombia ³Sixth year med student, Javeriana University, Department of Neurosurgery, San Ignacio University Hospital - Colombia ⁴Fourth year med student, Javeriana University, Department of Neurosurgery, San Ignacio University Hospital - Colombia

Introduction: The deformity of the vertebral column and in particular the scoliosis are clinical manifestations that represent a public health problem, especially by the disability and the impact that they have in the quality of life. Its prevalence has been estimated in 32% in the general population and 68% in the elderly population [1]. The relevance of this clinical entity is evident given the tendency of appearance with aging, the deterioration in the quality of life of those who manifest it and the costs of its study and treatment. Despite the extensive study that has been developed around scoliosis, multiple unknowns remain unresolved. Although several of the pathophysiological mechanisms that lead to scoliosis are known, in many cases, none of these explains the cause of this entity [2]. There are even occasions where scoliosis itself is a manifestation of adaptation to another entity. It is thus that this study arises, with the purpose of analyzing the literature and being able to emit a theoretical concept, which can describe the neurological mechanisms through which the scoliosis develops and those through which it responds to it. Material and Methods: Design: Systematic Revision. Source: PubMed, Ovid, Science Direct, EMBASE, Clinical Key, UpToDate and Scielo, between January 1st of 1976 and January 5th of 2017. Study Selections: We’ve selected several analytical, descriptive (Case series and Cohort study) and clinically experimental studies (performed in animals) about the role of the visual, oculomotor, vestibular, propioception - cerebellum, postural and cerebral systems in relation with idiopathic and degenerative scoliosis. Inclusion criteria: We included articles about the pathophysiology of degenerative scoliosis, pathophysiology of idiopathic scoliosis, anatomical pathways of the cerebellum, oculomotor, proprioceptive and cortical systems involved in scoliosis. Also, texts about postural changes in response to vision, role of proprioception, cerebellum, vision, vestibular system, cortex and posture in scoliosis. Additionally, articles about the biomechanics of degenerative and idiopathic scoliosis were involved. Exclusion criteria: Articles in languages other than Spanish and English, as well as review articles, books and opinions. Results: In the search we identified 284 references of which 225 were considered relevant by title, abstract, species, language and year of publication. Of the relevant references, 172 articles were excluded because they did not meet the inclusion criteria and 6 because they did not provide relevant information. Finally, 47 studies, 40 analytical - descriptive clinical studies (between cohorts, report and series of cases) and 7 experimental studies were divided by theme as shown in table / graph 1. They were included in the discussion as topics with general information, 3 reviews of which abstracted information relevant to clinical description, epidemiology and demography. Conclusion: Vertebral deformity (in any of its segments) caused by scoliosis requires a basic etiological principle, which refers to the need to hold parallel gaze and the craneo-cervical relation to the horizon on which the individual moves. In this review we integrate the pathways and neurological mechanisms involved in a diagram that simplifies and serves as a starting point to understand the neurobiological mechanisms involved in vertebral deformity.

Deformity-Thoracolumbar (Adolescent)

P062 - Significance Of Sagittal Spinopelvic Parameters In Patients With Spondylolisthesis

Sai Krishna M L V¹, Deep Sharma², Jagdish Menon³

¹Senior resident, Dept of Orthopaedics, Jipmer, Puducherry - India ²Addl Professor & Head, Dept of Orthopaedics, Jipmer, Puducherry - India ³Professor, Dept of Orthopaedics, Jipmer, Puducherry - India

Introduction: Spondylolisthesis is a sagittal plane deformity resulting in slipping of one vertebra over the next. Various factors are implicated in the generation of this deformity. One important factor that has recently been proposed to be of significance is the sagittal orientation of the spine and pelvis and the correlation between the two. This correlation is calculated by measuring the various spinopelvic parameters on the full length standing lateral radiograph of the spine taken in a standardized manner. It has been proposed that a higher Pelvic incidence correlates with a higher incidence of spondylolisthesis. The correlation between spinopelvic parameters and incidence of spondylolisthesis has not been reported in the Indian ethnic population. We started our study with the hypothesis that patients with spondylolisthesis have a higher pelvic incidence. We aimed to confirm the hypothesis in our subset of patients. Also an attempt was made to identify if the value of these parameters was significantly different between the low grade and high grade listhesis groups. Materials and Methods: The study was approved by our institute review board and the ethical committee. We included all the patients visiting our OPD with complaints of LBP for more than three months, whose x-ray shows spondylolisthesis and who gave consent for the study. A total of 79 patients were thus included in the study. Another age and sex matched group of asymptomatic volunteers (n = 75) were also recruited as a control group. For all the subjects a standing lateral full spine radiograph was taken. The sagittal spinopelvic parameters were measured using the Surgimap spine software version 2.1.2 by a single observer. The parameters measured were pelvic incidence PI, pelvic tilt PT, sacral slope SS, thoracic kyphosis TK, lumbar lordosis LL. The comparisons were drawn between the patients and controls using appropriate statistical methods. Results: The mean values in the asymptomatic group are PI-47.85, PT-13.03, SS-34.8, LL-54.68, TK-24.03. In the listhesis group are PI-65.32, PT-21.30, SS-44.13, LL-54.08, TK-25.49. There was a significant difference between the normal and the listhesis groups among PI, SS, PT (p < 0.001). Conclusion: Patients with Spondylolisthesis were found to have a higher pelvic incidence, sacral slope, pelvic tilt, lumbar lordosis when compared to controls. And this difference is found to be statistically significant.

P063 - Reliability And Validity Of The Arabic Version Of The Early Onset Scoliosis 24 Items Questionnaire (EOSQ-24)

Yahia Hanbali¹, Haytham Musmar², Tony Perry³, Asif Hanif⁴, Khaldoun Bader⁵, Alaaeldin Ahmad⁶

¹Resident Doctor, Arab Care Hospital, Ramallah - Palestinian Territory, Occupied ²General Practitioner, Al-Rahma Poly Clinic, Nablus - Palestinian Territory, Occupied ³Assistant Programme Manager, Waltham Forest Clinical Commissioning Group, London - United Kingdom ⁴Asst. Prof & Head of Department Bio-Statistics, GD-PGMI, Lahore - Pakistan ⁵School of Public Health, Al-Quds University, Jerusalem - Palestinian Territory, Occupied ⁶Associate Professor, Polytechnique university, Hebron - Palestinian Territory, Occupied

Introduction: Early-onset scoliosis (EOS) can have many negative impacts on patients’ development and health-related quality of life (HRQoL). The treatment of EOS aims to improve HRQoL and reduce the burden on their caregivers, as well as improving their development. Despite the importance of radiographic parameters in assessing the treatment outcomes, it has been shown that these parameters were insufficient to evaluate the efficacy of the treatment. The Early Onset Scoliosis Questionnaire -24 (EOSQ-24) was developed to measure the wider dimensions of outcomes. A validated Arabic version was created to be used in the Arab societies. Methods: Translation and cross-cultural adaptation were performed on the original English EOSQ-24 by a specialized committee and based on published guidelines. 58 EOS patients were chosen randomly and Arabic version of EOSQ-24 was applied to their caregivers in structured interviews after signing a consent form that clarifies the aim of the study. Reliability was assessed using Cronbach’s α and item-total statistics for the whole questionnaire initially and then the same reliability statistics were applied to each domain separately. Data quality was assessed by mean, median, percentage of missing data, ceiling and floor effects. Discriminative validity was done by using non parametric tests. Results: The response for all items was excellent with only 1.7% of responses missing (1.7%). The floor effect ranged 0% to 36.2% of patients and ceiling effect ranged 0% to 46.6%. Cronbach’s alpha test reliability was found excellent (0.919), internal consistency of all domains was excellent (Cronbach α: 0.903-0.918). Corrected item-total correlations were good for all domains (>0.3). Only one item (Question 21) showed low Corrected item-total correlations (r = 0.222). However, Cornbach’s alpha not increased significantly when this item was deleted 0.920. It was found that the Arabic version is able to discriminate patients according to ambulatory status (p = 0.02), complications after surgery (p = 0.035) and curve severity (p = 0.039). Conclusion: The first adapted Arabic version of EOSQ-24 has been found to have good validity, reliability and it can be used to assess children in Arab societies with early onset scoliosis.

P064 - Shoulder Balance In Lenke Type 2 Adolescent Idiopathic Scoliosis: Should We Fuse To T2?

Huiliang Yang¹, Gi Hye Im², Lei Wang¹, Chunguang Zhou¹, Limin Liu¹, Yueming Song¹

¹Department of Orthopaedics, Sichuan University, Chengdu - China ²Department of Orthopaedic Surgery, Harvard University, Boston - United States

Introduction: There are many different systems recommending upper instrumented vertebra (UIV) for Lenke type 2 adolescent idiopathic scoliosis (AIS), several of which suggest that all Lenke type 2 AIS patients should be fused to the second thoracic vertebra (T2). However, all UIV selecting systems do not accurately predict postoperative shoulder balance. We investigated whether fusing to T2 could prevent postoperative shoulder imbalance and identified circumstances under which to fuse up to T2. Material and Methods: We retrospectively collected all patients with typical Lenke type 2 AIS who received surgery by one spine surgeon in our hospital from 2010 to 2014. Lateral shoulder balance was assessed utilizing radiographic shoulder height difference (RSH), coracoid height difference (CHD), clavicle-rib intersection difference (CRID), and clavicle angle (CA). Medial shoulder balance was assessed by T1 tilt angle and first rib angle (FRA). Lateral shoulders were considered to be level if the absolute value of RSH was less than 10 millimeters. All patients were divided into two groups as follows: 1) T2 group: UIV of T2 (n = 49); and 2) below-T2 group: UIV of T3 (n = 24) or T4 (n = 6). Patients were assessed before surgery and at final follow-up with a minimum follow-up duration of 24 months. Results: Seventy-nine typical Lenke type 2 AIS patients were identified. Preoperative CHD and CA were significantly associated with postoperative lateral shoulder imbalance (both p = 0.045), whereas the UIV level was not significantly associated with it. Both fusing to T2 and to below T2 could improve RSH (p < 0.001 and p = 0.001, respectively). Fusing to T2 slightly worsened CHD, CRID, and CA at last follow-up (all p < 0.001), while fusing to below T2 improved these lateral shoulder balance parameters (p = 0.042, p < 0.001, and p = 0.007, respectively). For medial shoulder balance, fusing to below T2 worsened T1 tilt angle and FRA at last follow-up (p = 0.025 and p < 0.001, respectively), while fusing to T2 effectively kept these medial shoulder parameters in balance. In addition, for patients with an elevated left border of T1, the T2 group had worse preoperative T1 tilt angle but gained better postoperative T1 tilt angle than the below T2 group (p < 0.001 and p = 0.040, respectively). Conclusion: Preoperative lateral shoulder balance, more so than the UIV level, can strongly influence postoperative lateral shoulder balance. Fusing to T2 can only effectively improve medial shoulder balance, not lateral shoulder balance (CHD, CRID, and CA). Moreover, a positive T1 tilt angle is an indicator for fusing to T2 to improve medial shoulder balance.

P065 - Improving Compliance And Results Of Adolescent Idiopathic Scoliosis; The Alder Hey Scan Jacket

Mike Smith¹, Mohamed Mohamed², Marcus De Matas², Sudarshan Munigangaiah², JM Trivedi², NT Davidson²

¹Department of Spinal Surgery, Alderhey Childrens Hospital, Liverpool - United Kingdom

Introduction: Brace management of scoliosis is known to be an effective means of controlling flexible and reducing the risk of curve progression. Traditionally braces have been cumbersome and poorly tolerated however recent innovations have allowed for the development of patient specific braces that are both cosmetically and functionally better. We present our experience with the Alder Hey Scan Jacket Brace. Methods: This was a single centre, retrospective study of adolescents undergoing brace management of idiopathic scoliosis between 2010 and 2016. All patients were treated with the Alder Hey Scan Jacket using software created by Rodin 4d and jacket manufactured by Relief Orthotics. Surface topography is created using a dedicated hand-held 3D camera linked to an iPad and Ronin 4d Software. This image is combined with a 3D reconstructed image of the patients skeleton acquired by the EOS 2D/3D imaging system. This software model is then used is for the initial brace design and allows simulated modification of the brace before fabricating and fitting to the patient Results: 73 patients were included, 63 (86%) were female with an average age at start of treatment of 11 years (8 - 13). 65 patients (89%) were Risser grade 3 or lower and the average Cobb angle pre-brace was 31º (23 - 42º) and average follow-up was 18 months (8 - 36 months). Eleven patients went on to have surgical correction at 23 months (8 - 56 months) with a Cobb angle of 67º (54 - 84º). Brace management continued for 50 patients (68%) with a Cobb angle of 27º (15 - 40º) and the remaining 12 patients (16%) with an average Cobb angle of 32º were discharged (20 - 40º). Pre-treatment coronal balance was 1.3 cm (IQR 0.69 - 2.7 cm) and 1.6 cm post-brace treatment (IQR 0.5 - 2.5 cm). One patient (1.4%) was not compliant with brace treatment. Conclusion: Brace management of idiopathic scoliosis in adolescents has had poor compliance in the past however this new technology allows lighter, better fitting braces increasing compliance. Our ALderhey Scan jacket brace appears successful thus far in reducing the progression of scoliosis in our cohort of patients

P066 - Short-Term Results Of Fusionless Scoliosis Correction: A Prospective Cohort Study

Roderick M. Holewijn¹, Tsjitske Haanstra¹, Sayf S.A. Faraj¹, Marinus de Kleuver², Agnita Stadhouder¹

¹Department of Orthopedic Surgery, VU University Medical Center, Amsterdam Movement Sciences, Amsterdam - Netherlands ²Department of Orthopedic Surgery, Radboud University Medical Center, Nijmegen - Netherlands

Introduction: Spinal fusion surgery for adolescent idiopathic scoliosis (AIS) is far from optimal due to its invasiveness and prolonged postoperative recovery. A novel posterior peri-apical concave distraction device for fusionless scoliosis correction was used. It has a ball and socket mobile rod-screw joint, allowing almost unrestricted motion, and a ratchet mechanism for gradual postoperative device elongation and curve correction. Theoretically, this is achieved by postoperative spinal bending exercises. The treatment has potential benefits: minimal blood loss, a small incision and a quicker postoperative recovery. To our knowledge this is one of the first prospective IRB approved cohort studies with the aim to demonstrate safety and effectiveness. The preliminary results are presented. It was hypothesized that surgical treatment with the posterior peri-apical concave distraction device results in a post-operative Cobb angle of <35° without serious complications. Material and Methods: After extensive process IRB and medical ethical committee approval was obtained. AIS patients 12-17 years old with a Lenke type 1 or 5 curve, a Cobb angle of 40-55° with correction on the bending X-ray to <35°, Risser stage 1-4, rotation <15° and compliance for postoperative exercises were consecutively included. Results: 12 patients were included. Mean follow-up: 6.6 months. Serious adverse events: one re-operation was performed because of a protrusion of the proximal pedicle screw through the vertebral endplate 10 months post-operatively. Adverse events: one patient was treated with an oral antibiotic because of a superficial wound infection. To date there was no loss of correction or instrumentation failure. The Cobb angle decreased from 43.6° ± 3.5° to 30.5° ± 5.9° (p < 0.001). Levels bridged: 5 (range 4-6). Incision length: 16.0 ± 2.9 cm. Blood loss: 31 ± 43 ml. Surgery time: 59 ± 9 min. Length of stay: 2.7 ± 1 days. Conclusion: These preliminary data show that surgical treatment with the posterior distraction device is potentially a safe and less-invasive option for well-selected AIS patients. Long-term follow-up will determine the risk of instrumentation failure of this fusionless treatment.

P067 - Two-Stage Versus One-Stage Posterior Spinal Fusion For Severe Spinal Deformity: An Analysis Of Safety And Clinical Outcome

Yong Qiu¹, Xu Sun¹, Zhen Liu¹, Enze Jiang¹, Zezhang Zhu¹

¹Department of Spine Surgery, Drum Tower Hospital, Nanjing University Medical School, Nanjing - China

Introduction: To compare the safety and clinical outcomes of the two-stage posterior release, traction, and correction surgery versus the one-stage pre-operative traction and posterior surgery in patients with severe and rigid scoliosis. Materials and methods: 30 patients treated with two-stage spinal release, halo-femoral traction, and posterior spinal fusion for severe spinal deformity were matched with 30 patients treated with one-stage posterior spine fusion surgery after halo gravity traction according to curve type and etiology. The minimum follow-up period was two years, and the radiographic and clinical data were analyzed and compared. Results: The pre-operative Cobb angle and flexibility were similar between the two groups (122.70° vs. 122.53°, P = 0.965; and 12.95% vs. 10.56%, P = 0.249). At the end of traction, a statistically significant higher correction rate was achieved in the two-stage group when compared with the one-stage group (31.77% vs 18.89%, P < 0.001). The higher correction rate in the two-stage group was maintained after the posterior fusion surgery (44.68% vs 38.00%, P = 0.028). Larger total blood loss (2073.33 ± 684.777 vs. 1528.33 ± 816.604, P = 0.007) and shorter time of traction time (21.37 ± 2.498 vs. 83.23 ± 28.476, P < 0.001) was found in the two-stage group. Besides, no significant difference was found between the two groups in term of the pre-operative SRS-22 outcome. No neurological or other major complications were observed in this study. Conclusions: Compared with the one-stage pre-operative traction and posterior fusion surgery, the two-stage posterior release, traction, and posterior fusion surgery can provide better correction rate for severe scoliosis patients, without increased complications.

P068 - Could Pelvic Parameters Determine Optimal Postoperative Thoracic Kyphosis In Lenke Type 1 Ais Patients?

Yong Qiu¹, Shunan Liu¹, Hongda Bao¹, Zezhang Zhu¹, Bangping Qian¹, Zhen Liu¹

¹Department of Spine Surgery, Drum Tower Hospital, Nanjing University Medical School, Nanjing - China

Introduction: A proper restoration of sagittal alignment is essential in AIS patients, but few studies provided a formula to predict an optimal surgical TK gain in AIS patients. A formula was recently proposed (LL = (PI+TK)/2+10) to predict the optimal lumbar lordosis (LL) in adult spinal deformity patients, which has not been validated in adolescents. The current study aims to establish a formula with thoracic kyphosis (TK) and pelvic parameters in normal adolescents and predict an optimal TK with this formula pre- and post-operatively in Lenke 1 adolescent idiopathic scoliosis (AIS) patients. Materials and Methods: A total of 60 asymptomatic adolescents were used to validate the proposed formula. The subject was considered to match with the formula, if the difference between the virtual TK and the theoretical TK was less than 10°. Then regression analysis was performed to establish a new formula to predict TK in adolescents. The predictive efficiency of the new formula was also validated in 40 Lenke 1 AIS patients. Results: Of the 60 asymptomatic adolescents, only 26 (43.33%) asymptomatic adolescents matched with the adjusted formula: TK = 2×(LL-10)-PI. The paired t test revealed a significantly different theoretical TK (tTK) compared to the virtual TK (41.23 ± 18.29° vs. 24.80 ± 8.75°, P < 0.001). Multiple linear regression showed that TK had a relationship with LL, SS and age (R² = 0.331): TK = -0.785×LL-0.843×SS+0.858×age+3.754. There were 27 (67.50%), 32 (80.00%) and 35 (87.50%) Lenke 1 AIS patients matched this formula preoperatively, postoperatively and at the last follow-up. Conclusion: Our results revealed that the predictive formula for sagittal alignment for adults was not applicable in adolescents. This study established a new predictive formula for TK based on asymptomatic adolescents. In Lenke 1 AIS patients, post-op TK in 87.5% of patients matched the predictive value, indicating that the new formula can be considered as a reference when making a surgery strategy.

P069 - Alternative To The “Y” Inverted Surgical Access In Patients With Scoliosis Secundary To Myelomeningocele

Diego Bezerra¹, Luis Rocha¹, Dulce Grimm¹, Carlos Aguiar¹, Luiz Ávila ¹, Fernando Soccol¹

¹Departamento de Ortopedia, Hospital Pequeno Príncipe, Curitiba - Brazil

Introduction: Neonatal closure of the spina bifida, pressure sores, scars secondary to flap rotation and recurrent infection are common complications in spina bifida patients before then spinal deformity correction. This can make the deformity surgery procedure a challenge and increase the chance of complications like dural sac lesions, musculocutaneous coverage fail and necrosis of the skin. The Y-inverted was described by Mayfield in order to decrease these complications, but necrosis at the Y angle is a risk. We describe a variation of this technique to further reduce cutaneous complications. Material and Methods: Retrospective study by reviewing medical records of patients with myelomeningocele and poor skin conditions, surgically treated by a modified surgical access of the “Y” inverted between january 2013 and december 2015 and followed for one year minimum. Results: The technique was applied in six patients. Two patients evolved with skin complications in the immediate postoperative period, only one of them required surgical intervention for debridement and suturing. In another patient it was necessary to perform two surgical reviews due to hardware faillure without skin complications in all approaches. Conclusion: The variation of the “Y” inverted technique is a great alternative to the traditional incision and “Y” inverted to present good results in patients with spina bifida associated with poor skin conditions treated surgically for correction of spinal deformities.

P070 - Comparative Cost Analysis Of Conventional And Magnetic Controlled Growing Rods In Early-Onset Scoliosis – A Single Center Experience

Ravi Ghag¹, Luigi Nasto², Eva Habib², Christopher Reilly¹, Firoz Miyanji¹

¹Department of Orthopaedic Surgery, BC Children’s Hospital and University of British Columbia, Vancouver - Canada ²Department of Orthopaedic Surgery, BC Children’s Hospital, Vancouver - Canada

Introduction: Conventional growing rods (CGR) and magnetic controlled growing rods (MCGR) are growth-friendly devices for treatment of early-onset scoliosis (EOS). CGR requires repeated surgical lengthening under general anesthesia, whereas MCGR lengthening is performed noninvasively in a clinic setting. Unit cost for MCGR is higher than CGR, however, the need for surgery to perform each lengthening for CGR may eventually offset the initial lower cost of the procedure. The aim of this study is to provide a comprehensive single-center cost comparison analysis of CGR and MCGR. We hypothesize that MCGR will show cost savings when compared to the traditional approach of using CGR. MCGR reduces the need for repeated surgical procedures as in CGR, thus overall benefit will be to the patient population. In addition to cost, complications, clinical efficacy, and outpatient hospital resource utilization should be taken into account when comparing these two methods. Material and Methods: A retrospective, cost-comparative single centre study was conducted. Charts of 21 consecutive patients with EOS secondary to idiopathic (n = 8), syndromic (n = 10), and neuromuscular (n = 1) etiology, treated with CGR (n = 13) and MCGR (n = 6), with minimum follow-up ≥ 12 months were reviewed. Costs related to surgical procedures (i.e. inpatient admission, index surgery, lengthening, and final fusion), outpatient procedures, and complication management were gathered using Service Recipient Costing methodology. Descriptive and Mann-Whitney U statistics were performed. Data is presented as median and IQR (α = 0.05). Results: Patients with CGR (follow-up 61.7 [43.9–82.0] months) had a total of 88 inpatient lengthening procedures performed. 11 surgical procedures performed due to complications (4 infections, 7 hardware-related), and 6 conversions to final fusion. MCGR patients (follow-up 29.7 [17.1–30.3] months) collectively had 45 outpatient lengthening procedures with one revision case converting to fusion. Demographic variables, pre- and post-operative coronal and sagittal deformity measurements and trunk height, operative time, blood loss, and length of stay (LOS) were not statistically significantly different between the two groups. CGR surgical implants cost $17 567 [14 472–23 989], while MCGR implants cost $36 311 [31 298–44 430] (p = 0.006). MCGR outpatients lengthening cost $562[361–738], this is significantly lower compared to inpatient CGR lengthening at $14 905 [11 558–28 784] (p < 0.001). Conclusion: Aggregate MCGR cost at median follow-up of one year is similar to CGR, due to the high implant cost. This is the first study to report real comprehensive inpatient and outpatient costing data, and is furthermore compared with CGR cohorts to realize the true cost savings of MCGR. Long-term MCGR cohort follow-up is required with a maintained low revision rate to demonstrate superior cost savings.

P071 - Back Pain Related To Providence Night-Time Bracing, In Adolescent Idiopathic Scoliosis Patients - A Retrospective Cross-Sectional Study

Ane Simony¹, Helle Munk², Inge Beschau², Lena Quisth², Mikkel Osterheden Andersen¹

¹Center for Spine Surgery & Research, Middelfart Hospital, Middelfart - Denmark ²Ortos A/S, Odense M - Denmark

Introduction: Providence Night Time Bracing has since 2007 been the conservative treatment Adolescent Idiopathic Scoliosis (AIS) Patients, in Denmark. The aim of the study was to investigate the presence of back pain and anatomical area of pain AIS patients, after termination of treatment with Providence Night Time Braces. A further aim was to investigate the correlation between Cobb and pain intensity, and the correlation between pain and Physical Activity and Social function. Material and Methods: 62 AIS patients, received a questionnaire collecting information of the frequency of back pain, functional and social limitations due to back or leg pain, all derived from the Dallas Pain Questionnaire (DPQ) and the Dallas Pain Drawing (DPD) by mail. Included in the questionnaire were also 3 descriptive questions, exploring when the pain appeared the first time and its correlation to brace treatment and presence of back pain after brace weaning. Patients diagnosed with AIS, Cobb 20-45° with apex from T7 was included in this study. All patients had received treatment with Providence Night Time Braces and no additional treatment or Scoliosis Specific Exercises was offered to the patients. Cobb was determined on the latest standing AP radiograph at termination of treatment, 12 months after brace weaning. The results were analysed for correlation between Cobb and the total pain score (Q-total) and correlation between Cobb and physical activity or Social function. Dallas Pain Drawing was used to investigate the pain modalities experienced by the patients. Results: 62 AIS patients were included in the study, 40 patients returned the questionnaire. The data collected was analysed with IBM SPSS statistics 21 software. The intensity of pain was measured in mm from the 7 questions included in the DPQ, and a total sum score Q-total was calculated. The severity of pain was divided into three groups, Mild pain, 0-30 mm. Moderate pain 31-69 mm and Severe pain 70-100 mm. 26 patients reported some sort of back pain, 10 patients reported no back pain and 4 patients returned the questionnaire incomplete. 20 patients, who reported back pain, had pain in the Mild category. No correlation was found between Cobb and the intensity of back pain, Cobb and Physical activity or Cobb and Social function. A correlation was detected between Q-total and Depression. Deep and stabbing pain was the most frequent pain modality reported by the patients. Correlation was found between the curve type and the area of pain in the DPD. Conclusion: Back pain is frequently reported from AIS patients, after termination of Providence Night Time Brace treatment. The majority of patient’s reports mild intensity of pain, and pain is primarily located in the thoracic or lumbar region. The presence of back pain in 80% of the patients after termination of part time bracing, might suggest that physiotherapy is not only beneficial for AIS patients being braced > 16 hours daily. Further cohort studies, with a frequent evaluation of back pain during bracing is needed, to investigate the topic.

P072 - Identifying The Development Of Kinesiophobia In Adolescents Undergoing Spinal Fusion Surgery Leads To Improved Recovery

Diana-Luk Ye¹, Neil Saran², Jean A. Ouellet², Catherine E. Ferland³

¹Department of Experimental Surgery, McGill University, Montreal - Canada ²Division of Orthopedics, Shriners Hospital for Children-Canada, Montreal - Canada ³Department of Anesthesia, McGill University, Montreal - Canada

Introduction: Adolescents undergoing spinal fusion surgery with instrumentation are at great risk to develop kinesiophobia (fear of movement) and consequent morbidities like disability. However, kinesiophobia is only measured with a questionnaire, and no objective physical tests are used. The aims of the study were to identify the presence of kinesiophobia after surgery and to evaluate its association with the patient psychological profile. Methods: Twenty-three 10-18 year-old patients with Adolescent Idiopathic Scoliosis scheduled to undergo spinal fusion surgery at the Shriners Hospital were enrolled. Before surgery, pain catastrophizing and pain intensity were assessed with self-reported questionnaires. After surgery, kinesiophobia was measured with the TAMPA scale on postop day 1, 2 and 5 and 6 weeks after. Functional disability was also assessed. Correlation and paired t-tests analyses were performed. Results: Pain intensity before surgery was negatively correlated with kinesiophobia six weeks after surgery (r = -0.46, p = 0.04). Pain catastrophizing and helplessness positively correlated with kinesiophobia on day 1 (r = 0.43, p = 0.06; r = 0.42, p = 0.07), day 2 (r = 0.41, p = 0.17; r = 0.45, p = 0.06) and day 5 after surgery (r = 0.35, p = 0.12; r = 0.44, p = 0.06). Furthermore, pain helplessness during in-hospital stay was associated with kinesiophobia six weeks after surgery (p ≤ 0.05). Six weeks after surgery, 19 of 23 patients developed kinesiophobia, and a positive correlation was observed between kinesiophobia and functional disability (r = 0.39, p = 0.06) and helplessness (r = 0.44, p = 0.06). Conclusion: Presence of kinesiophobia weeks after surgery was observed in the majority of patients and is associated with functional disability. There is a clinical need to better characterize the observed fear of movement that could interfere with proper recovery.

P073 - Convex Manipulation Versus All Level One Side Instrumentation In Lenke Type 3 And 6 Scoliosis: Technical Features, Results And Complications

Leonardo Oggiano¹, Sergio Sessa¹, Cloe Curri¹, Guido La Rosa¹

¹Department of Surgery, Orthopaedic Unit, Bambino Gesù Children’s Hospital, Rome - Italy

Introduction: We report perioperative and 3-year results in a consecutive series of adolescents affected by double-curve idiopathic scoliosis alternatively treated by instrumentation only at the convex side of each curve versus all-level one side pedicle screws instrumentation. Material and Methods: From January 2014 to January 2016 we surgical treated 24 consecutive patients (19 F, 5 M, mean age 13 years) affected by double curve adolescent idiopathic scoliosis (Lenke type 3, 18 patients, and Lenke type 6, 6 patients). The population was divided in two groups: in group 1 (16 patients) we performed an instrumentation using polyaxial pedicle screws only at the convex side of each curve; in group 2 (8 patients) we performed an all level one side pedicle screws instrumentation, covering both the convexity and the concavity at the side of instrumentation. In all cases motor-evoked potentials monitoring was used. Mean follow-up time was 34 months. Results: The average percentage of coronal correction was similar in two groups (74 ± 5% in group 1 and 79 ± 4% in group 2), with no neurological complications. In group 1 we performed a simultaneous bilateral derotation and manipulation on both convex side of the curves, instead in group 2 we performed a unilateral derotation and correction maneuvers on the side of the instrumentation. Concerning the post-operative thoracic kyphosis, we observed a slight decrease of mean values compared to pre-operative measurements (mean reduction of thoracic kyphosis 5° ± 2°). The operative time was a little bit different between the two groups (210 ± 30 minutes in group 1 and 230 ± 30 in group 2) with a comparable mean blood loss (600 ± 100 ml). At 34-month follow-up no substantial changes in coronal nor in sagittal plane were observed. Conclusion: This case-series study shows the effectiveness and the safety of convex manipulation in Lenke type 3 and type 6 scoliosis. The coronal correction obtained with this technique is comparable to that obtained with the traditional concave derotation. Other advantages are the short operative time, the low intra-operative blood loss and, mostly, a lower risk of neurological complications. Unlike the single curves, the management of double curves by only convex instrumentation requires a simultaneous derotation of both curve, in order to achieve the maximum correction of the deformity.

P074 - Cost Effective Scoliosis Surgery: Comparison Between Low Cost Indian Implants And Imported Implants

Rishi Mugesh Kanna¹, Ajoy Shetty², S Rajasekaran³

¹Associate Consultant, Dept of Orthopaedics, Ganga Hospital, Coimbatore - India ²Senior Spine Consultant, Dept of Orthopaedics, Ganga Hospital, Coimbatore - India ³Chairman- Dept of Orthopaedics, Trauma & Spine Surgery, Ganga Hospital, Coimbatore - India

Introduction: Corrective surgery for Scoliosis is an expensive surgery with average per patient cost being approximately $100 000 in the United States. In developing countries lower per capita income, socio-economic status and inadequate health care insurance, often make the surgeon and the patient, to opt for low cost Indian pedicle screws for deformity correction surgeries (7-10 times less expensive than imported screws). However there is no available data regarding the safety, efficacy, durability and cost effectiveness of low cost Indian screws in comparison to imported screws in scoliosis surgeries. Materials and Methods: We performed a retrospective review of case records of consecutive patients who underwent posterior deformity corrective surgery for Adolescent Idiopathic Scoliosis and completed a minimum of two year follow-up. Patients with congenital scoliosis, deformity > 100 degrees, pathological curves such as neurofibromatosis, neuro-muscular scoliosis, need for complex osteotomy except Ponte’s osteotomy and age > 20 years were excluded from the study. Both groups of patients had an uniform surgical technique operated by the same surgical team, pedicle screws placed strategically, and curve correction achieved by rod rotation technique (titanium or cobalt chrome rods used). Patients’ demographics, pre and post operative Cobb angle, Lenke curve type, curve flexibility based on supine side bending radiographs, number of screws used, total vertebral segments fused and cost analysis based on implants, length of stay and complications were studied. The patients chose an Indian versus imported implant based on their affordability. Results: 92 patients (female: male = 82:10) formed the study group and were divided into two groups - Group A (Indian) – n = 30 and Group B (Imported) – n = 62. The distribution of curves were as follows - Lenke 1 – 40, II – 3, III – 13, IV – 1, V – 25, VI – 10 which was comparable in both groups except for higher number of Type 5 in Group B (p < 0.05). The mean age in years was comparable (16.7 +/- 3.8 vs 15.2 +/- 3.3, p = 0.05). There was no significant difference in the various study parameters including the mean pre-operative Cobb angle - 59.4 ± 14.4° vs 56.8 ± 13.5° p = 0.3990, curve flexibility – 39.9 ± 13.5% vs 41.5 ± 14.5%, p = 0.6, mean post-operative Cobb angle – 21.6° vs 17.8°, p = 0.5, mean curve correction achieved – 65 ± 23.8% vs 69 ± 25.7%, p = 0.46, mean levels fused – 10.9 ± 2.3 vs 10.4 ± 2.6, p = 0.36, and the screw density ratio – 0.68 vs 0.69, p = 0.9, and the mean loss of correction at final follow-up, 2.4 degrees vs 2.6 degrees, p = 0.71, between the two groups. Other surgical variables like duration, blood loss, length of stay and peri-operative complications were also comparable. But the mean cost per patient of $2339.42 in Group A was significantly less than in Group B ($9045.75) (p < 0.001). Conclusion: The significantly lower cost Indian pedicle screws provided similar deformity correction which was maintained at two years. The mean levels fused, number of screws used and screw density ratio was similar in both groups. With concerns about raising health care costs, a low cost model for spine deformity correction surgery is a welcome need of the hour.

P075 - The Radiological Outcome Study Of Adolescent Idopathic Thoracolumbar/Lumbar Scoliosis Treated With Short Segment Anterior Fusion

Nur Aida Faruk Senan¹, Sudhir Kumar Sri Kumar¹, Boon Beng Tan², Yian Young Teo², Mohamad Zaki Mohd Amin², Chung Chek Wong²

¹Deparment of Orthopedics, Sarawak General Hospital, Kuching - Malaysia ²Deparment of orthopedics, university Malaysia Sarawak, Kuching - Malaysia

Introduction: Anterior spinal fusion was the historically preferred in treatment for Lenke 5C curves in adolescent idiopathic scoliosis because of better curve correction, allowing powerful derotation while preserving more motion segments. However with the advancement of posterior fixation systems to derotate the curve, the trend changed. The benefit of saving distal motion segment and preventing denervation of the powerful paraspinal muscles is still a valid reason to approach from anterior. We present our experience in treating these selected group of patients with short segment fusion using monoaxial pedicle screws with staples and a one rod system. Material and Methods: We retrospectively reviewed patients with adolescent idiopathic scoliosis (Lenke 5) that was treated with short segment anterior fusion surgery at a single centre from 2012-2014. There was a total of 11 patients. One was lost to follow up and was excluded from the study. The radiographs were assessed preoperatively then postoperatively at 2 years. Radiographic views that were taken were the AP standing, lateral, right and left bending as well as fulcrum bending. Results were analyzed using statistical analysis (SPSS). Results: There were 9 females and one male patient with the average age of 16.6 years old at the time of surgery. All patients underwent anterior lumbar fusion from T12 –L3, except one patient who was fused from T12 to L2. The average pre op Lumbar Cobb angle was 53.8 degrees and was corrected to 18.4 post operatively, producing a correction rate of 65%. The fulcrum flexibility rate was 44% (p value < 0.05. The fulcrum bending correction index was 104% (p value < 0.05). There was no post op neurological deficit, infection or major vessel injury seen in all patients. At the 2 year follow up, there was no incidence of significant progression of the lumbar curve and also the thoracic non structural curve. Conclusion: Short segment lumbar fusion surgery may be a good option to treat Lenke 5 curves. The fulcrum bending films provided a good indication of the flexibility of the lumbar curve despite having no ribs as anchorage points for the fulcrum. There were no long term curve progression seen at 2 years.

P076 - The Use Of Rhbmp-7 In Surgical Treatment Of Paediatric Patients Affected By Symptomatic Grade I Isthmic Spondylolisthesis: A 10 Years Follow-Up Study

Sergio Sessa¹, Leonardo Oggiano¹, Cloe Curri¹, Guido La Rosa¹

¹Department of Surgery, Orthopaedic Unit, Bambino Gesù Children’s Hospital, Rome - Italy

Introduction: Posterolateral fusion is a common treatment for lumbar spondylolisthesis. Most often, autologous bone from the iliac crest is used for arthrodesis. However, failure of fusion remains a common complication following this procedure. There has hence been interest in the development and use of bioactive molecules capable of inducing bone regeneration in hopes of achieving higher fusion rates, while also avoiding the morbidity of autograft harvest. BMPs exert an osteoinductive effect by stimulating differentiation of mesenchymal stem cells into mineral-depositing osteoblasts. Osteogenic protein-1 (rhBMP-7) is a member of the transforming growth factor-beta superfamily of extracellular proteins involved in bone growth and formation. Spinal fusion studies have been demonstrated the efficacy and safety of OP-1 in adults. The goal of our study is to prove the efficacy of OP-1 in paediatric population affected by spondylolisthesis grade I. Materials and Methods: After local Ethical Committee approvement and written informed consent, 14 patients (mean age 13,6 years, range 8-16 years) affected by symptomatic grade I isthmic spondylolisthesis were treated between 2004 and 2006 by intertrasversary in situ fusion (Wiltse approach). A mixture of small bone chips obtained from in situ decortication, OP-1 (eptotermin alfa, 3.5 mg) and autologous stem cells taken from iliac crest were used in all procedures. A TLSO brace was used in the postoperative time for two months. Results: Results were retrospectively evaluated with a minimum follow-up of 145 months (range 132-160).Clinical and radiological outcomes were assessed before surgical treatment, at three, six and twelve months and several years after surgery by CT and X-rays. Fusion mass was evaluated according to Carreon criteria. Mean operative time was 120 minutes (range 90-150 minutes) with mean blood loss of 300 ml. Overall complete fusion was observed at one-month X-rays control in all but 2 patients (85%) presenting with unilateral fusion. These results were confirmed at following X-rays and CT controls. At 3-months follow-up 3 seromas were recorded (21%); complete recovery was achieved by steroid therapy in 1 case and reintervention in 2 cases. Conclusion: Many studies reported the safety and efficacy of OP-1 as a replacement for iliac crest autograft in posterolateral lumbar fusion in adults. In children OP-1 has recently proven to be effective in healing of persistent nonunion with no major adverse event recorded. In the present study spinal arthrodesis was achieved in 85% of paediatric patients by a short operative time, low bleeding and reduced postoperative pain, with a mild incidence of seroma at 3-month follow-up (21%). Further studies are needed to better understand the efficacy and benefit of this technique in pediatric patients.

P077 - Early Onset Scoliosis In Children Less Than 5 Years: Role Of Single Sub-Muscular Growing Rod Instrumentation

Naresh-Babu J¹, Arun-Kumar Viswanadha¹

¹Department of Spine Surgery, Mallika Spine Centre, Guntur - India

Introduction: Early Onset Scoliosis (EOS) in elder children has no controversy regarding its management, but till date there is no universal consensus in age group of 2-5 years to cast or perform growth rod instrumentation. When bracing or casting treatment is not possible or fails to prevent scoliosis progression especially in children aged between 2-5 years, fusion less growing instrumentation is the only acceptable solution to control the scoliosis while preserving spinal growth. Present study evaluates the safety, efficacy and radiological outcome of indigenously developed growing rod (GR) technique in the management of early onset scoliosis and discusses the technical considerations in children less than 5 years old. Material and Methods: 18 patients with early onset scoliosis (age less than 5 years) were treated with GR technique with a minimum of two distractions and a follow-up of 2 years were included. Mean age at the time of GR instrumentation was 3.7 years (2-5yrs). 5 mm pedicle screws were inserted at distal stable and proximal stable vertebrae with two small incisions and two 5 mm rods were inserted submuscularly and joined by rod-rod connector. Rods were contoured to the sagittal profile while taking care to allow sliding. Radiographic evaluation included measured changes in scoliosis Cobb angle, kyphosis, lordosis, frontal and sagittal balance, length of T1-S1 and instrumentation over the treatment period, and space available for lung ratio. Results: The mean scoliosis improved from 75.6° to 53.6° (27.8%). Coronal Plumb line showed relative improvement of 52.7% where as the trunk shift showed improvement of 95.2%. Space available for lung (SAL) improved by 3.4% on convex side and 2.5% on concave side. There was 9.2% improvement in the hemi-thoracic area on convex side compared to 4.4% improvement on concave side. Conclusion: Our experience with GR technique is found to be safe and effective in the treatment of EOS in young children less than 5 years old. They are highly effective in correcting the trunk shift to improve the coronal balance and cosmetic appearance in children. There were no complications related to instrumentation since children above 2 years can safely accommodate 5.5 mm pedicle screws.

P078 - Current Capacity In Secondary Curves In Patients With Type 1 Lenke Curves Submitted To Selective Arthrodesis

Thiago Maia¹, Charbel Jacob Jr¹, Igor Machado Cardoso¹, José Lucas Batista Jr¹, Marcus Alexandre Novo Brazolino¹, Louise Goncalves Paris¹, Arthur Felipe Lauf Melotti¹

¹Department of Orthopedics Santa Casa de Vitoria, Vitoria - Brazil

Introduction: The general principle of the Lenke system is that major curves and minor structural curves must be arthrodesed. Compensatory curves depend on the development of the main curve, and therefore must be corrected spontaneously when the main curve is instrumented. Thus, ideally, following arthrodesis of the thoracic curve, the naturally-unplugged lumbar curve would naturally accommodate the correction of the thoracic curve. In the curves classified as Lenke 1 it has been shown that a selective arthrodesis is the appropriate treatment, since through this we can obtain a correction of the compensatory curves by performing an arthrodesis with a smaller number of segments, which would bring advantage to this patient. Materials and Methods: Descriptive, retrospective study of patients with EIA, classified as Lenke I, who underwent selective arthrodesis surgery and were followed for at least 24 months after surgery. The sample consisted of 16 patients, 5 males and 11 females, aged 14 to 23 years, with EIA who underwent selective arthrodesis between July 2008 and December 2014. The main curves and compensatory according to the Cobb method, through panoramic radiographs of the spine in orthostatic position at three moments: preoperative, recent postoperative (4-6 months) and late postoperative period (at least 24 months after surgery). The sample was characterized by descriptive analysis techniques. The Cobb angle was described by the mean and standard deviation. Results: The mean Cobb score on the pre-operative anteroposterior radiographic examination was 57.4 for the main thoracic curve and 34.4 for the compensatory curve (lumbar curve); in the recent postoperative time it was 19.2° for the main thoracic curve and 14.4° for the compensatory curve; while in the late postoperative time it was 23.6° for the main thoracic curve and 18.7° for the compensatory curve. The results of the non-parametric test of Friedman indicated that there is statistical difference for the main and compensatory curves in the preoperative, recent and late postoperative radiographs (p <0.05). The multiple comparison performed in the BioEstat 5.3 program indicated a significant difference between preoperative and recent postoperative radiographs and between preoperative and late postoperative radiographs. Conclusions: The present study evidences the success of the surgical treatment through selective arthrodesis of Lenke type I EIA. The surgical treatment promotes good correction of the main curve in the recent postoperative period and maintenance of the coronal balance after 24 months. The lumbar compensatory curve also presents significant correction and maintenance after 24 months.

P079 - Pelvic Fixation With Alar-Iliac Screws Technique In Spina Bifida Scoliosis Surgical Treatment

Luiz Muller Ávila¹, Luís Eduardo Munhoz da Rocha¹, Carlos Abreu De Aguiar¹, Coracy Gonçalves Brasil Neto¹

¹Grupo de Cirurgia de Coluna, Hospital Pequeno Príncipe, Curitiba - Brazil

Introduction: Spina bifida occurs due to a closure defect of the neural tube involving a spinal cord and meninges, between the 3 rd and 4th weeks of the embryonic period. Spinal deformities presents early and become severe around 7 to 10 years of age, about 50% of patients may develop scoliosis. Age and motor impairment were the main determinants of the onset of deformity, reaching 93% at the thoracic level and 72% at the lumbar level. The surgical treatment of spinal arthrodesis aims at correcting the deformity and restoring the trunk and pelvis balance, aiming at an improvement of the patient's quality of life. The presence of lombar kyphosis and a pelvic obliquity are indications of prolongation of fixation to pelvis. There are several techniques described for pelvic fixation, our group used a technique in S2 alar-iliac. Material and Methods: This study aims to retrospectively evaluate the complications related to the use of fixation with the S2 iliac screws in individuals with spina bifida, from data obtained prospectively from the cases operated by our group. We performed a retrospective study of data obtained prospectively from cases operated between January 2015 and January 2017. We had 12 cases operated, which were analyzed as radiographic images and clinical records to search for complications, such as failure of material and pain or wound at level of fixation in S2. Results: Six male patients and six female patients were operated. The mean age of the patients was 13.4 years. The mean follow-up was 10 months (ranging from 4 months to 18 months). Radiographic analysis showed only one case (7%) with the complication associated with failure of the material at the level of the sacroiliac fixation at S2, there was a release of the head of the left S2AI polyaxial screw. There was a case of fracture of the rod at L3-L4 level, related a patient fall, characterizing the traumatic event as the complication provider, without compromising S2AI fixation. Another complication reported, but not associated with the fixation was a rod fracture at T11-T12 level due to pseudoarthrosis, which needed a reoperation. However, without compromising the fixation of iliac level. There was no clinical report of wound or pain complications directly to the material at the S2AI fixation level. Conclusion: The technique of pelvic fixation in scoliosis in spina bifida with the use of S2 alar-iliac screws has shown satisfactory results in our group, with only one case of complication directly related.

P080 - The Column in Von Recklinghausen Syndrome. Case Series and Literature Review

Henrique Dagostin De Arjona¹, Rodrigo D’Alessandro De Macedo¹, Bruno Pinto Coelho Fontes¹, Jader Andrade Neto¹, William Feijó Scharf¹, Cristiano Magalhães Menezes¹, Christiano Esteves Simões¹, Kleber Miranda Linhares¹

¹Orthopedic Spine Group, Hospital Da Baleia Serviço Prof. Matta Machado, Belo Horizonte - Brazil

Introduction: Neurofibromatosis type 1 (NF1), also known as Von Recklinghausen syndrome was described in 1882 by Friedrich Daniel Von Recklinghausen. It is a congenital, hereditary and familial disease, determined by an autosomal dominant gene with irregular penetrance and variable expressivity. Scoliosis is the most common alteration (occurs between 10 and 60% of cases), usually involves the dorsal spine, and the curve is of acute angulation. Scoliosis in NF-1 can be dystrophic and non-dystrophic, being the dystrophic ones more common, with tendency to progress and to provoke neurological deficit. Scoliosis not dystrophic resembles the idiopathic scoliosis curve pattern and behavior for progression. The objective of this study is to analyze patients with the diagnosis of Von Recklinghausen syndrome underwent surgical treatment and conduct a literature review. Material and Methods: Retrospective analysis of patients’ records of Hospital da Baleia - Orthopedic Spine Group Prof. Matta Machado, with diagnosis Von Recklinghausen syndrome from January 2010 to May 2017. Of these, 07 patients presented clinical evidence according to the criteria for correction of the deformity and were submitted to surgery. Patients who did not follow the follow-up, incomplete medical records and inadequate radiographic evaluation were excluded from the study. Sixty patients were included in the study. The Cobb method was used for radiographic analysis of the deformities. A measurement of the angular deformity through the caudal and cranial end plates was performed and regional kyphosis was performed using the superior and inferior vertebral plates of the deformities. The patients were analyzed for age, sex, vertebral integrant, clinical picture, type of treatment, control instrument, number of screws and angulation of the deformity. Results: It was found in all patients with severe deformities sharp bends, with an average of 105 degrees of thoracic scoliosis associated with hipercifoses. In addition, there was a female predilection of 2:1 in this series of cases, mean age was 13 years and all patients had a first degree relative with neurofibromatosis. 50% of patients had handed convexity curved chest. All patients underwent double approach and cranial traction for four weeks. The draw showed an average of 32 degrees from the main deformity correction. There was an eleven m ean instrumented levels. Four patients underwent blood transfusion during the procedure. Only one case evolved with superficial infection in the operative wound. Conclusion: While in idiopathic scoliosis the purpose of the spine surgeon is correction of the deformity, in neurofibromatosis the objective is to stop the deformity, therefore a small correction can only be considered a good result in NF1 patients.

P081 - Incidence Of Negative Plumb Line In AIS

James Todd¹, Jan Herzog¹, Niv Bhamber¹, Tim Bishop¹, Jason Bernard¹, Darren Lui¹

¹Department of Trauma and Orthopaedics, St George’s University Hospital, London - United Kingdom

Introduction: Adolescent Idiopathic Scoliosis (AIS) is the most prevalent form of idiopathic scoliosis (90%). Emphasis has previously been on coronal deformity but the relation to sagittal balance is not fully understood. This study investigates Sagittal Vertical Spine (SVA) and thoracic kyphosis (TK). A positive SVA is a measure of poor sagittal balance but the clinical relevance of a negative value has not been established. Material and Methods: This was a retrospective review of 116 AIS first presentation cases. 87 had lateral radiographs. A new classification for negative SVA was devised. Results: 82.76% patients had a (-)SVA (mean -4.19 cm ± 2.38 cm). New (-)SVA classifications A> -3.5 cm, B = -3.5 to -6.5 cm, C< -6.5 cm. A = 43.06%, B = 33.33% C = 23.61%. Categorisation of TK: Hypokyphosis = 39.39%, Normal = 48.48%, Hyperkyphosis = 12.12%. Mean TK was 24° ± 11° (normal = 20°-40°). There was no correlation between (-)SVA and TK (R2 = 3×10-6). 27 cases underwent Posterior Spinal Fusion surgery (PSF). In patients with a (-)SVA prior to surgery (82.76%), SVA remained negative in 77.30% and mean SVA decreased from -3.64 cm to -4.05 cm. Of the cases with a positive SVA prior to surgery, 3 became negative post-operation (60.00%) and mean SVA decreased from 2.20 cm to 0.95 cm. Conclusion: The majority of first presentation AIS patients have negative sagittal balance. 3 categories have been devised. PSF is known to be a hypokyphotic procedure but more importantly may create a further negative SVA. Further research needs to be conducted to establish SVA in a healthy population and the association of back pain in AIS with (-)SVA.

P082 - Blood Management Strategies In Spine Deformity Surgery: Chris Hani Baragwanath Academic Hospital, Johannesburg, South Africa’s Experience (2015 -2017)

UN Fred Ukunda¹, Akinwande Akinjolire¹

¹Division of Orthopaedic Surgery, Faculty of Health Sciences, University of Witwatersrand, Johannesburg - South Africa

Introduction: Studies have shown that spine deformity surgery is associated with significant blood loss and use of costly allogeneic blood transfusion. At our centre, there is no established blood management protocol for these cases, as this is done on “ad hoc” basis. The current blood interventional practices include pre-operative assessment, intraoperative strategies such as the use of cell savers, antifibrinolytics, surgical haemostasis, as well as post-operative strategies focused on allogeneic blood use and restrictive transfusion policy (low haemoglobin transfusion trigger), mainly practiced in the intensive care unit. Hence, this review is an attempt to establish a blood management protocol in this patient cohort at our institution. Material and Methods: This is a three-year retrospective review of a prospectively collected data from the orthopaedic spine unit. Forty three (43) consecutive patients (post tuberculosis kyphosis, idiopathic scoliosis and other deformities) underwent spine deformity surgery between 2015 - 2017. Results: None of the patients required preoperative blood optimization as their haemoglobin levels was found to be satisfactory. The patients with failed scoliosis correction that requires revision surgery have larger blood loss and required allogeneic blood transfusion. Transfused patients had more blood loss that was directly proportionate to the magnitude of the curve, number of segments fused, duration of surgery, as well as number of osteotomies, and whether the bone scalpel was utilised or not. Furthermore, the use Tranexamic acid intraoperatively, either as a bolus or continuous infusion minimises the need for allogenic blood transfusion. Conclusion: The amount of blood loss in spine deformity surgery is directly related to the magnitude of the curve, the number of segment fused and the duration of surgery. For optimal care of these patients, it is important to have a blood management protocol that is clear, understood and adhere to by everybody in the perioperative period.

P083 - Effect Of Direct Vertebral Rotation In Single Thoracic Adolescent Idiopathic Scoliosis

Dong-Gune Chang¹, Jae Hyuk Yang², Jung-Hee Lee³, Ravish S Patel², Seung-Woo Suh², Jin-Hyok Kim⁴, Jong-Beom Park⁵, Se-Il Suk¹

¹Department of Orthopedic Surgery, Inje University Sanggye Paik Hospital, Seoul - Korea

²Department of Orthopedic Surgery, Korea Universtiy Guro-Hospital, Seoul - Korea

³Department of Orthopedic Surgery, Kyung Hee University Hospital, Seoul - Korea

⁴Department of Orthopedic Surgery, CM Hospital, Seoul - Korea

⁵Department of Orthopedic Surgery, Uijeongbu St. Mary’s Hospital, Uijeongbu - Korea

Introduction: There is a paucity of literature demonstrating the long term surgical outcomes of DVR in patients with thoracic AIS. Materials and Methods: AIS patients with single thoracic curves (n = 110) treated by STF from neutral vertebra (NV) to NV or NV-1 with a minimum 2-year follow-up were retrospectively analyzed. The patients were divided into two groups; non-DVR (n = 63) and DVR groups (n = 47). Patients in non-DVR group underwent STF with bilateral rod derotation maneuver (RD) while patients in DVR group underwent STF with bilateral RD and DVR maneuver. Results: There was significant difference in the number of fused segments between the non-DVR and DVR groups (P < 0.000). There was significant difference in the curve magnitude of main thoracic curve postoperatively (P = 0.001) and at the last follow-up (P = 0.006) between the non-DVR and DVR groups. However, there was no significant difference in proximal thoracic (PT) and lumbar curve postoperatively (PT curve: P = 0.186, lumbar curve: P = 0.155) and at the last follow-up (PT curve: P = 0.250, lumbar curve: P = 0.060) between the two groups. There was significant improvement of LIV tilt and disc angle and relatively well maintained during the follow-up period in both groups. There was no significant difference of rotation of apical vertebra and end vertebra preoperatively (P > 0.05). However, there was significant difference postoperatively (P < 0.05), and at the last follow-up (P < 0.05). Conclusions: DVR could effectively achieve better deformity correction, and more rotational correction with reduced number of fusion segments. However, it is important that DVR should be applied in proper direction with adequate force.

P084 - Results of Growing Rod Instrumentation in Non-Idopathic Early Onset Scoliosis. A Single Centre Prospective Series

Amer Alkot¹

¹Department of Orthopedic And Spine Surgery, Assiut University, Sohag - Egypt

Introduction: Early onset scoliosis is defined as scoliosis that starts before the age of 10 years whatever its etiology. It is one of the major spine issues that necessitates further studies and long term follow up of various surgical and non surgical tools. Treatment of EOS with growing rods have unpredictable outcome that may be very successful or even catastrophic according to etiology, severity and flexibility of the curve and associated kyphosis. Material and Methods: Between 2009 and 2016, twenty two patients (14 girls and 8 boys) with EOS due to non idiopathic causes were treated with Growing Rods Instrumentation. The study protocol was approved by our Institution Review Board and all patients’ parents signed an informed consent. The age at the index surgery ranged between 2.5 and 5 years (mean 3.75). Lengthening was done every 6 months. Only patients who had completed 2 lengthening procedures are included in this series. Results: The total number of surgeries performed was 132 (22 index surgeries and 85 lengthening procedures, and 25 unplanned surgeries). Four patients were excluded because of incomplete follow up. The remaining 18 patients included 8 congenital scoliosis, 7 neurofibromatosis, 2 skeletal Dysplasia, and 1 neuromuscular scoliosis patients. The number of lengthening procedures for each patient varied between 2 to 10. The follow-up duration ranged between 18 to 108 months. The initial mean Cobb angle improved after the index surgery from 82.3^o to 68^oand after the second lengthening to 64^o and after the fourth lengthening to 56^o. The initial mean kyphosis angle improved after the index surgery from 59.5^oto 53^o and after the second lengthening to 51.3^o and after fourth lengthening to 47.3^o. Twenty five complications were recorded during the study period. These included 8 superficial infections, 6 rod breakage, 5 proximal anchoring failure, 4 distal screws pull out and 2 deep infections with MRSA that needed implant removal and termination of the lengthening procedures. Conclusion: Despite high number of complications, growing rods are still a successful options for EOS due to non idiopathic early onset scoliosis.

Deformity-Thoracolumbar (Adult)

P085 - Significance Of Sagittal Spinopelvic Parameters In Chronic Low Back Pain Patients With And Without Spondylolisthesis

Sai Krishna M L V¹, Deep Sharma², Jagdish Menon³

¹Senior resident, Dept of Orthopaedics, Jipmer, Puducherry - India ²Addl Professor & Head, Dept of Orthopaedics, Jipmer, Puducherry - India ³Professor, Dept of Orthopaedics, Jipmer, Puducherry - India

Introduction: Alteration in the normal values of the spinopelvic parameters have been implicated in causing low back pain, degenerative spine diseases and even sagittal plane deformities like spondylolisthesis. Few studies have implicated high pelvic incidence as a causative factor for the listhesis. The recent literature also suggested that the best functional outcomes after any spinal surgery were achieved when these parameters have been normalized. Though these values have been well quantified in the Caucasian population, there is a dearth of information in other racial groups. Thus, in our study, we aim to identify the importance of the spinopelvic parameters in the causation of low back pain and spondylolisthesis. Materials and Methods: The study was approved by our institute review board and the ethical committee. All the patients visiting our OPD with exclusive complaints of LBP for more than three months, without any other discernible cause and who gave consent for the study were taken as one group. Patients with chronic low back pain whose x-ray shows spondylolisthesis and who gave consent for the study were included in the second group. A total of 79 listhesis patients, 67 chronic low back pain patients were included in the study. Lateral sagittal digital radiographs of the whole spine including the base of skull up to the proximal 1/3 thigh were taken in standing position (patient is naturally standing up, looking horizontally, hands resting on a vertical support, upper limbs relaxed and elbows half bent). The parameters measured were pelvic incidence PI, pelvic tilt PT, sacral slope SS, thoracic kyphosis TK, lumbar lordosis LL. All measurements were performed using the Surgimap Spine software version 2.1.2.The values thus obtained were compared between the groups. Results: The mean values in patients with low back pain were PI-48.04, PT-12.61, SS-35.5, LL-50.57 and TK-26.79. In the listhesis group were PI-65.32, PT-21.30, SS-44.13, LL-54.08, TK-25.49. There was a significant difference in the PI, SS, PT and LL between the chronic low back pain without deformity and with listhesis (p < 0.001). Conclusion: There is statistically significant difference among the spinopelvic parameters (PI, SS, PT, LL) between the chronic low back pain patients with spondylolisthesis and without any deformity. Higher spinopelvic parameters are associated with slip in chronic low back pain patients.

P086 - Changes Except The Skeletal System After Surgical Treatment Of Kyphotic Deformity Secondary To Ankylosing Spondylitis: A Systematic Review

Yong Hai¹, Jingwei Liu¹

¹Department of Orthopedics, Beijing Chao-Yang Hospital, Capital Medical University, Beijing - China

Introduction: In addition to changes of skeletal system after spinal osteotomy for treatment of kyphotic deformity in advanced stage AS patients, many other changes related to the patients’ quality of life were reported. This article is to conduct a systematic review of literature to determine changes except the skeletal system after surgical treatment of kyphotic deformity secondary to ankylosing spondylitis. Methods: On 19 June 2017 we searched the databases PubMed, EMBASE, Clinicalkey and Cochrane Library without time restriction. Selected papers were assessed by published guidelines. We investigated changes except the skeletal system after surgical treatment of AS kyphosis. Results: The initial search yielded 888 citations. Ten of these studies met the inclusion and exclusion criteria. None of them was level I or level II evidence studies, one was level III evidence study, and nine were level IV evidence studies. Changes were reported including aorta length, abdominal morphology, digestive function, cardiopulmonary function, psychological status and sexual activity. Conclusions: In addition to skeletal changes after spinal osteotomy for treatment of kyphotic deformity in advanced stage AS patients, many other changes were reported. Spine surgeons should pay more attention to these life quality related changes and be aware of potential risks from them when performing osteotomy for advanced stage AS patients.

P087 - The Analysis Of Postoperative Outcomes For The Patients With Thoracic Ossification Of Posterior Longitudinal Ligament: Does The Occupation Rate Of Ossification Influence Postoperative Outcomes?

Kensuke Shinohara¹, Tomohiko Hirose¹, Kazuhiro Takeuchi¹, Shinnosuke Nakahara¹

¹Department of Orthopaedic Surgery, Okayama Medical Center, Okayama - Japan

Introduction: Conservative therapy is ineffective for thoracic ossification of posterior longitudinal ligament (T-OPLL) to the most of cases, and the most of patients are performed surgical treatment. In addition, there are no reports that the influence of occupation rate of ossification (ORO) to postoperative outcome. The aim of this study was to evaluate the relationships between ORO and postoperative outcomes for the patients with T-OPLL. Methods: This study included 33 patients (15 male and 18 female, the mean age 59 years old) who underwent surgical treatment at one institution during 10 years period from 2005 to 2016. The authors evaluated clinical data (BMI, length of hospital stay, follow-up period, surgical methods, operation time, intraoperative bleeding, ORO, surgical outcomes, radiographic changes) from medical and operative records retrospectively. The surgical outcomes were evaluated using modified Japanese Orthopaedic Association (JOA) scale score (maximum point: 11) and the improvement recovery rate. The JOA scale score ware collected at preoperative, postoperative, and final follow-up point. The anteroposterior diameters of thoracic spinal canal and T-OPLL were investigated from CT axial view in the narrowest level. The ORO was defined as below: (The anteroposterior diameter of T-OPLL / The anteroposterior diameter of thoracic spinal canal) × 100 (%). The relationships between ORO and the improvement recovery rate ware also examined. Results: The mean BMI was 26 and the mean length of stay was 26 days. The mean follow-up period was 67 months. Surgical methods consisted of posterior decompression (n = 3), anterior decompression and posterior instrumented fusion (n = 2), and posterior decompression and instrumented fusion (n = 28). The mean operation time was 213 minutes and the mean intraoperative bleeding was 418 ml. The mean ORO was 46%. The mean improvement recovery rate was 49%. There were no deteriorations of sagittal alignment on radiographic examination. A correlation coefficient between ORO and the improvement recovery rate was r = - 0.19, which was very weak negative relationship. When the patients were divided into two groups; ORO less than 49% (Small group: S group, n = 16) and ORO more than 50% (Large group: L group, n = 17), the improvement recovery rate by ORO was 55.2% in S group and 44.2% in L group, respectively. There was no significant difference in two groups. The older patients and the patients with poor preoperative JOA scale score tended to deteriorate the improvement recovery rate. Conclusions: The postoperative outcomes for T-OPLL were favourable. The correlation of ORO and the improvement recovery rate was very weak. This study shows that ORO does not influence the improvement recovery rate and suggests that the ages and preoperative JOA scale score tend to influence the improvement recovery rate.

P088 - Minimum Detectable Change And Minimum Clinically Important Difference Of Health Related Quality Of Life Parameters In Adult Spinal Deformity

Selcen Yuksel¹, Selim Ayhan², Vugar Nabiyev³, Prashant Adhikari⁴, Montse Domingo-Sabat⁵, Ibrahim Obeid⁶, Francisco Javier Sanchez Perez-Grueso⁷, Frank Kleinstueck⁸, Ferran Pellise⁹, Ahmet Alanay¹⁰, Emre Acaroglu³, European Spine Study Group ESSG⁵

¹Department of Biostatistics, Yildirim Beyazit University School of Medicine, Ankara - Turkey ²Department of Neurological Surgery, ARTES Spine Center, Ankara - Turkey ³Department of Orthopaedics and Traumatology, ARTES Spine Center, Ankara - Turkey ⁴ARTES Spine Center, Ankara - Turkey ⁵Institut de Recerca Vall d’Hebron, Barcelona - Spain ⁶Spine Unit, Centre Hospitalier Universitaire de Bordeaux, Bordeaux - France ⁷Spine Unit, Hospital Universitario La Paz, Madrid - Spain ⁸Spine Surgery, Schulthess Klinik, Zurich - Switzerland ⁹Spine Unit, Hospital Universitari Vall d’Hebron, Barcelona - Spain ¹⁰Department of Orthopaedics and Traumatology, School of Medicine, Acibadem Mehmet Ali Aydinlar University, Istanbul - Turkey

Introduction: Measurement and comparison of health related quality of life (HRQOL) have become an essential component of clinical results evaluation in any field even in adult spinal deformity (ASD). By definition, only treatments associated with a substantial HRQOL improvement should be promoted. Minimum clinically important difference (MCID) is a measure of this substantiality, whereas minimum detectable change (MDC) is the minimal amount of change score outside of measurement error that may reflect true change. The aim of this study was to calculate MCID and MDC values of total scores of the Core Outcome Measures Index (COMI), Oswestry Disability Index (ODI), Physical Component Summary (PCS) and Mental Component Summary (MCS) of the Short Form 36 (SF-36) and Scoliosis Research Society 22 (SRS-22) in surgically and non-surgically treated adult spinal deformity (ASD) patients who have completed a Global Rating of Change Scale (GRCS) at pre-treatment and 1-year follow-up. Material and Methods: A total of 893 ASD patients from a multicentric international database; MDC and MCID values were calculated for COMI, ODI, SF-36 MCS, SF-36 PCS and SRS-22 scores for surgical (n = 185) and non-surgical (n = 86) patients who had completed a GRCS question at pre-treatment and 1-year follow-up. MDC was calculated by multiplying the standard error of measurement (SEM) by the z score associated with the desired confidence level and the square root of 2, adjusting for sampling from 2 different measures whereas MCID was calculated as mean change score on scales based on this anchor question, corresponding to patients with anchor question responses larger than 0; using latent class analysis. Results: All differences between means of baseline and 1st year postoperative total score measures for all scales demonstrated statistically significant improvements in the overall population as well as the surgically treated patients but not in the non-surgical group. The calculated overall MDC and MCID scores of HRQOL parameters that were obtained from study population were 1.34 and 2.62 for COMI, 10.65 and 14.31 for ODI, 6.09 and 7.33 for SF-36 PCS, 6.14 and 4.37 for SF-36 MCS, 0.42 and 0.71 for SRS-22, respectively. The calculated MCID values for surgical and non-surgical treatment groups were 2.76 and 1.20 for COMI, 14.96 and 2.45 for ODI, 7.83 and 2.15 for SF-36 PCS, 5.14 and 2.03 for SF-36 MCS, 0.94 and 0.11 for SRS-22, respectively. Conclusions: This study has described the MCID and MDC values for surgically and non-surgically treated ASD patients, pooled and separately. Our MDC and MCID values validate those from previous studies. On the other hand, this study has specifically demonstrated that the MCID values may be different for diverse sub-populations, based on the modality of treatment. This finding may be important in evaluating studies which report treatment results based on ‘solid’ MCID value presumptions.

P089 - Modified Technique Of Transforaminal Lumbar Interbody Fusion For Segmental Correction Of Lumbar Kyphosis: A Safe Alternative To Osteotomies?

Sebastian Weckbach¹, Heiko Reichel¹, Michael Kraus¹, Tugrul Kocak¹, Friederike Lattig²

¹Department of Orthopedics University of Ulm, Ulm - Germany ²Department of Spine Surgery, Berit Klinik, Speicher - Switzerland

Introduction: Sagittal rebalancing of a fixated lumbar hypolordosis (kyphosis) is very important to gain satisfactory results. To correct a misalignment vertebral column resection or pedicle subtraction osteotomies are favored, disregarding the relatively high complication rates. The aim of this study was to evaluate the efficiency and safety of a new modified transforaminal lumbar fusion technique as an alternative. Methods: We conducted a retrospective review (06/2011-06/2015) of a prospective database at an University hospital. Inclusion criteria were adult patients with a fixated lumbar hypolordosis and the need of monosegmental correction of more than 10° with an mTLIF. Exclusion criteria consisted of minor aged patients and polysegmental corrections. Study parameters were the perioperative complications and the achieved postsurgical lordosis. The follow up period was 6 months. Results: A total of 11 patients could be included. The mean segmental lordosis was -2.3° ± 12.4° (range -22° to 14°) preoperative and 15.5° ± 10.5° (range 0° to 29°) postoperative. The degree of correction was 17° ± 5.7° in mean per treated segment (range 12° to 29°). No neurologic or vascular complications occurred. No substantial loss of correction or implant failure was noted during the 6-month follow-up. Conclusion: The modified transforaminal lumbar fusion technique is a safe method to correct a fixated lumbar kyphosis. The potential of segmental correction is comparable to pedicle subtraction osteotomies but sparing potentially healthy segments.

P090 - The Risk Factors Analysis Of Proximal Junctional Kyphosis After Long Segment Corrective Surgery For Degenerative Lumbar Scoliosis

Yan Zeng¹, Xiaolin Chen¹, Zhongqiang Chen¹, Zhaoqing Guo¹, Qiang Qi¹, Weishi Li¹, Chuiguo Sun¹

¹Orthopedic Department, Peking University Third Hospital, Beijing - China

Introduction: To observe the incidence and risk factors of proximal junctional kyphosis (PJK) after long segment corrective surgery for degenerative lumbar scoliosis, and evaluate its influence to clinical results and life quality. Material and Methods: All the 60 patients of degenerative lumbar scoliosis underwent long segment corrective surgery in our hospital.The average age was 63.2 years. The average scoliosis Cobb angle was 28.5°. The patients were divided to PJK group and control group (no PJK) according to the follow-up results.The single variable and multi variables analysis were made for patient characteristics, surgery risk factors and radiological risk factors before and after surgery. Preoperative and follow-up VASfor low back pain and leg pain, ODI and SRS-22 scores for life quality were compared between PJK group and non-PJK group. Results: The average number of instrumentation and fusion segments was 6.7 ± 1.3. The mean follow-up duration was 40.6 ± 14.9 months (24-81 months). PJK was developed in 11 of 60 patients (18.3%) until the final follow-up, and which were enrolled in the PJK group. The other 49 patients without PJK formed non-PJK group. The multivariate Logistic regression revealed 3 independent risk factors: preoperative proximal junctional angle (PJA)>9º, postoperative adding of PJA>3º, and preoperative SS < 25º, which increased 19 times, 22 times and 23 times more likely to have PJK than those without the risk factors respectively. The PJK group had a significant higher score in VAS than control group, and the improved rate was significantly lower than control group.The SRS function/activity scores and appearance improved rate of PJK were significantly lower than control group. Conclusion: In a mid-term follow-up of minimum 24months, the PJK incidence is highafter long segment corrective surgery for degenerative lumbar scoliosis, and influence the clinical results and life quality of the patients. For the patient who has independent risk factors, more appropriate surgery strategy and follow-up plan should be made.

P091 - Modified Iliac Screw Technique Is Necessary And Sufficient In Clinical Practice For Long Spinal Fusion Of Osteoporotic Asian Patients

Atsuji Kashiro¹, Toyohito Iwami¹, Hiroshige Debata¹, Tetsuro Takai¹, Takahiro Iizuka¹

¹Takai Hospital, Nara - Japan

Introduction: Several Lumbo-sacral fixation techniques are reported in literatures. S2 Alar Iliac Screw (S2AI-screw) is considered as the strongest fixation technique in spine surgery. However this technique requires a precise entry point and trajectory. Modified Iliac Screw (MI-screw) technique (Fig.1) is easier and safer than S2AI-screw and also enough strong. We report morphological features and advantages of MI-screw technique in osteoporotic Asian patients. Material and Methods: Twenty patients who underwent lumbo-sacral fusion with MI-screws (ZODIAC, Alphatec Spine USA) were enrolled. Age:75.0 (60-85)yo. F13, M 7. Height:158 ± 12 cm. Weight:61 ± 15 kg. Fused segments:4.4 (2-13) segments. Modified Iliac Screw Technique (Fig.1)

No extra-exposure of Iliac Crest.

Identify S2 foramen with fingers.

Identify the corner between ventral medial wall of Ilium and Sacral roof (entry point).

Proceed pedicle probe to the ilium 40-45 degree ventrally and 30-45 degree caudally.

Insert polyaxial screw>7.5 mm. The screw heads (L4-S1 and MI-screws) are lined in one direct position.

Methods: STUDY 1: Morphological Features in S2 and Ilium. Morphological features are evaluated with pre-operative CT scanned in the gantry of S1 endplate (Fig. 2,a). The possible entry point of screw (diameter: 7.5 mm, screw head:12 mm) is evaluated on this CT image in condition that screws penetrate sacral roof and ilium without violation of surrounded cortex. The distance of the possible entry point is measured from the center of sacrum. And the trajectory of S2AI screws is also measured (Fig. 2,b). STUDY 2: Evaluation of Modified Iliac Screw on post-operative CT. All MI-screws were evaluated at 3 weeks on CT concerning the position of screws. Lumbo-sacral fusion were evaluated on X-ray after 1,2,3 and 6 months. Results: STUDY 1: The distance of S2AI-screw is left: 18.2-22.7 mm and right: 15.2-24.2 mm from the center of sacrum. The trajectory was left: 37.0-57.7° and right: 42.5-57.3°. If S2AI-screws were used in all patients, only 2 screws were safely inserted in S2 alar and ilium because of small S2 roof and large screw heads. STUDY 2: In all patients with MI-screws L5/s fusion was completed in 3 months after surgery .No apparent clinical symptoms related to MI-screws were observed in actual clinical practice. Conclusion: Spinal instrumentation should be safe. S2AI-screw technique requires precise entry point (4-9 mm wide) and trajectory of screws within 10-15°. Thus this technique is not suitable for daily clinical usage. MI-screw technique is not difficult even for young surgeons. And the screws enhanced lubo-sacral fixation without any clinical problems in this study. We recommend MI-screws as supplemental fixation technique. MI-screws are necessary and sufficient in clinical practices.

Figure 1.

Modified lliac Screw Fixation for lumbo-sacral lesion.

Figure 2.

a: Gantry of CT image for S2 and ilium, b: Trajectory (α-maximum, β minimum). Entry point distance from center of sacrum (a:min, b:max)

P092 - Outcome Of Xlif Technology In Patients With Degenerative Lumbar Spine Scoliosis

Vladimir Klimov¹, Ivan Vasilenko¹, Alexey Evsyukov¹, Sergey Ryabykh²

¹Federal Neurosurgical Center, Novosibirsk – Russia

²Director of Division Spine Pathology and Rare Diseases, MD, PhD, Ilizarov Center, Russia, AOSpineRF Education Officer Ortho

Introduction: To study the results of treatment of patients with degenerative lumbar spine scoliosis being operated by XLIF procedure. Material and Methods: From 2014 till 2017 84 patients with lumbar spine scoliosis were operated in the Federal Neurosurgical Center (20 men and 64 women). The patients’ age was 63 ± 7 years. The follow-up 12 months after: X-ray study, SCT, MRI of lumbar spine. Questionnaire survey according to visual analog pain scale (VAS), Oswestry Disability Index (ODI) and The Short Form-36 (SF-36). Deformity correction degree was estimated in frontal plain on Cobb. Scoliosis was classified according to SRS-Schwab classification. Target value of integrated indicators SVA, PT and PI-LL (PI minus LL) were defined adjusted for the age. Results: All patients were offered indirect decompression of neural structures according to XLIF method with correction of degenerative scoliotic deformity and restoration of spino-pelvic balance with transcutaneous, transpedicular fixation of spinal segments. 12 months after the surgical procedure decrease of pain syndrome in the leg according to VAS from 4.6/4 (3;7) till 1.4/1 (0;2) scores (p = 0.0002) was statistically significantly noted. Decrease of pain syndrome in back according to VAS from 5.9/6 (4:8) till 2.6/3 (1:3) scores (p = 0.0001) was statistically significant 12 months after the surgery. PT before the surgery was 23.9 ± 12,2⁰, 12 months later it was 16.8 ± 5,9⁰ (p = 0.0002). PI-LL was 12.1/13 (9;16) °, 12 months later - 7.9/8 (6;10) ° (p = 0.0008). Deformation angle according to Cobb before the surgery was 28 ± 3.5°, during check-up examination it was 9.2 ± 2.3° (p = <10^-14). Improvement of functional adaptation according to Oswestry Disability Index from 47.8 ± 17,4 till 38.5 ± 14,5 (p = 0.0273). According to SF36 PH before the surgery in average was 27.9/28.9 (24.6;29.4) scores, 12 months after the surgery - 35.4/36.1 (31.2;40.4) (p = 0.0014). MH in average 32.3/28 (23.6;38.1) scores, 12 months later - 40.1/37.6 (33.4;47.6) (p = 0.0113). Charlson comorbidity index – 56,6 ± 22,4. Pseudoarthrosis - 2 (1,04%) levels (192 levels), asymptomatic medial malposition - 2 (0.5%) of transpedicular screws (396 screws), end plate damage - 7 (3.6%), L4 weakness - 5 (5.9%), hyposthesia anterior surface of the thigh - 7 (8.3%), psoas hematoma – 2 (2,3%), persistent paresis of the hip flexor - 1 (1.1%), persistent weakness of anterior abdominal wall from the side of surgical access – 2 (2,3%). Conclusion: Application of XLIF in combination with MIS transpedicular fixation ensures restoration of impaired spino-pelvic balance in sagittal and frontal planes in patients with degenerative lumbar spine scoliosis. Local balance restoration of lumbar spine in this patients ensures regress of radicular pain by the indirect decompression of intervertebral foramen and decrease of back pain that leads to improvement of life quality.

P093 - The Influence Of Postoperative Apical Vertebra Location On Clinical Outcomes In Ankylosing Spondylitis Patients With Thoracolumbar Kyphosis

Bangping Qian¹, Zhuojie Liu¹, Yong Qiu¹

¹Department of Spine Surgery, Drum Tower Hospital, Nanjing University Medical School, Nanjing - China

Introduction: Relocation of apical vertebra after surgery is widely found in AS patients. However, the influence of postoperative location of apical vertebra on sagittal balance and clinical outcomes in AS patients has not been investigated yet. This study aims to evaluate the influence of postoperative location of apical vertebra on clinical outcomes in patients with thoracolumbar kyphosis secondary to ankylosing spondylitis (AS). Materials and methods: Sixty-four patients (60 males and 4 females), with a mean age of 34.28 ± 9.60 years (range, 17-59 years)and a mean follow-up of 35.56 ± 16.07 months (range, 24-98 months) were divided into 2 groups according to the postoperative location of apical vertebra (Group 1, T8 or above; Group 2, T9 or below). The radiographical measurements, including global kyphosis (GK), thoracic kyphosis (TK), lumbar lordosis (LL), sagittal vertical axis (SVA), sacral slope (SS), pelvic tilt (PT), pelvic incidence (PI) and 3 apex-related parameters (horizontal distance between C7 and apex, DCA; horizontal distance from sacrum to apex, DSA and horizontal distance measured between osteotomized vertebra and apex, DOA), along with clinical outcomes measured by health related quality of life (HRQOL) questionnaire were compared between the 2 groups postoperatively and at the last follow-up. Furthermore, a subgroup analysis of patients with apex located on T6-T11 was performed and 62 normal controls were enrolled for comparison between the whole AS cohort and healthy individuals regarding apical vertebra location of the thoracic spine. Results: The majority of apical vertebra location changed from T12-L2 preoperatively to T6-T9 postoperatively. SVA differed significantly both postoperatively (25.70 mm vs. 59.07 mm, P < 0.001) and at the last follow-up (32.92 mm vs. 61.30 mm, P = 0.003) between the 2 groups and patients form Group 1 had significantly smaller DCA than patients in Group 2 (69.03 mm vs. 103.11 mm, P < 0.001). Subgroup analysis demonstrated similar results, showing that patients with apex located at T8 or above had an average SVA<47 mm. There was a significant correlation between postoperative SVA and DCA. However, no significant difference was found in HRQOL between the 2 groups. Conclusion: AS patients with apex located at T8 or above after surgery tended to have better SVA correction (within 47 mm) than those who had a more caudally located apical vertebra, but apical vertebra location did not affect these patients’ HRQOL scores.

P094 - Comparison Of Kyphosis Correction And Maintenance Following Pedicle Subtraction Osteotomy Between Ankylosing Spondylitis Patients With And Without Ossified Anterior Longitudinal Ligaments Neighboring The Osteotomy Vertebra

Bangping Qian¹, Saihu Mao¹, Yong Qiu¹, Yang Yu¹, Bin Wang¹, Zezhang Zhu¹

¹Department of Spine Surgery, Drum Tower Hospital, Nanjing University Medical School, Nanjing - China

Introduction: The proportion of kyphotic AS patients receiving PSO with yet sufficient elasticity in the neighboring intervertebral disc has seen a substantial increase. There was a paucity of literature addressing a comparison of kyphosis correction and maintenance following PSO between two AS groups as stratified by the presence of neighboring bridging syndesmophytes. This study was to compare the amount of kyphosis correction and maintenance following pedicle subtraction osteotomy (PSO) between ankylosing spondylitis (AS) patients with and without ossified anterior longitudinal ligaments neighboring the osteotomized vertebra (OV). Materials and Methods: 71 thoracolumbar kyphotic AS patients treated with single-level PSO at our hospital between September 2010 and August 2014 were retrospectively reviewed, 32 of whom were stratified into the ossified group (OG). The operative corrections of multiple spino-pelvic sagittal parameters were assessed. Comparison of the contribution of adjacent disc wedging to total correction per PSO segment was made between the ossified and non-ossified groups (NG). The correction loss were also evaluated and compared with a minimum 2-year follow-up. Results: A significantly younger age (30.97 ± 8.28 vs. 40.31 ± 8.44yrs, p < 0.001), smaller pelvic incidence (PI) (43.03 ± 10.60 vs. 49.36 ± 9.75°, p = 0.011), greater wedging index of OV (1.17 ± 0.16 vs. 1.09 ± 0.08, p = 0.011) and larger local kyphosis (19.59 ± 10.84 vs. 13.56 ± 8.50°, p = 0.013) was observed in NG preoperatively. Patients in OG and NG accomplished comparable amount of kyphosis correction per PSO segment (40.22 ± 7.09 vs. 43.85 ± 8.71°, p = 0.062). However, the contribution of adjacent disc wedging to total correction per PSO was significantly larger in NG [8.10 ± 6.19 (18.5%) vs. 1.09 ± 2.88° (2.7%), p < 0.001]. By ultimate follow-up, the global kyphosis (18.26 ± 10.97 vs. 21.51 ± 10.89°, p < 0.05) and thoracic kyphosis (37.95 ± 11.87 vs. 42.87 ± 11.56°, p < 0.05) got deteriorated significantly in the NG but not OG, so was the further pelvic retroversion as represented by increased pelvic tilt (19.46 ± 8.13 vs. 23.44 ± 8.19°, p < 0.05) and decreased sacral slope (23.02 ± 9.12 vs. 18.62 ± 10.10°, p < 0.05). Loss of corrections concerning contribution of adjacent disc wedging was also statistically significant larger in NG (1.41 ± 3.27 vs. 0.22 ± 1.49°, p < 0.05). Conclusion: Our study might suggested that the evaluation and treatment methods of kyphotic AS patients needed to be fine-tuned with appropriate subgrouping into ossified and non-ossified ALL neighboring the OV as they were distinct groups with different PI, contributor of lordosing capability and prognosis that might require separate analysis.

P095 - Anterior Versus Posterior Approaches For Isthmic Spondylolisthesis: A Retrospective Analysis

Emre Yilmaz¹, Alonso Fernando¹, Tom O’Lynnger¹, Ronen Blecher¹, Rod Oskouian¹, Christian Fisahn¹, Jens Chapman¹

¹Swedish Medical Center, Swedish Neuroscience Institute, Seattle - United States

Introduction: Surgical approaches for isthmic spondylolisthesis can be done anteriorly or posteriorly. There are no strict guidelines on which method to use, and approaches are often selected based on surgeon preference. The purpose of this study is to compare patients who underwent posterior or anterior approaches for isthmic spondylolisthesis at a single institution and evaluate outcomes and assess complications. Material and Methods: From 2010 to 2015, all patients who underwent a posterior approach (PLF/PLIF/TLIF) or anterior approach to treat isthmic spondylolisthesis at a single institution were analyzed. All procedures took place at either L5/S1 or L4/5. Demographic data were collected and reviewed for this retrospective analysis. Patients younger than 18 years and older than age 75 were excluded from the study. The pre- and post-operative measurements of spondylolisthesis and degree of lumbar lordosis were measured using lateral x-rays. Post-operative improvement in radiculopathy was documented. Fusion rates at one and two year follow-up as assess on lateral x-ray were documented. Results: Between 2010 and 2015, fifty-four patients underwent surgical treatment for isthmic spondylolisthesis. Fourteen patients underwent anterior lumbar interbody fusion, and forty patients underwent a posterior approach. There were no significant differences in patients’ demographics or occurring of complications. The posterior approach group showed a significantly decreased length of stay (2.8 ± 1.9 days vs. 4.9 ± 1.3 days; p < 0.01). The anterior approach group demonstrated improved lumbar lordosis compared to the posterior group (62.8° ± 9.3 vs. 55.3° ± 10.6; p = 0.03) as well as greater improvement in symptoms of radiculopathy (92.9% vs. 85%; p = 0.03). 25 patients were available for two year follow-up. There were no significant differences in fusion rates at one year (80% anterior vs. 70.8% posterior; p = 0.68) or two years (80.0% anterior vs. 87.5% posterior; p = 0.66). Conclusion: Anterior and posterior approaches in the treatment of isthmic spondylolisthesis showed similar results overall. Posterior approaches had decreased length of stay. Anterior approaches were associated with statistically significantly higher post-operative lordosis and a higher degree of improvement in symptoms of radiculopathy. However, results with both approaches were generally satisfactory and choice of approach will be dictated by anatomic considerations as well as surgeon preference and comfort.

P096 - Proximal Response Of The Unfused Levels: The Impact Of Uiv Location In Degenerative Lumbar Scoliosis

Yong Qiu¹, Peng Yan¹, Hongda Bao¹, Zezhang Zhu¹, Bangping Qian¹

¹Department of Spine Surgery, Drum Tower Hospital, Nanjing University Medical School, Nanjing - China

Introduction: It has been demonstrated that the high prevalence of cervical sagittal malalignment after surgery would affect the quality of life in adult spinal deformity patients. The objective of this study was to investigate whether long instrumentation into upper thoracic region would benefit the post-op alignment of proximal unfused levels in degenerative lumbar scoliosis patients. Materials and Methods: A retrospective study was performed on 41 consecutive degenerative scoliosis patients (10 males and 31 females) with more than 2-year follow-up. The subjects were divided into two groups according to the location of upper instrumented vertebra (UIV): upper thoracic (UT) group with the UIV located between T4 to T6; lower thoracic (LT) group with UIV located between T9 to T11. T test and ANOVA were performed for statistical analysis. Results: 19 patients were classified into the UT group and 22 into LT group with mean age of 59 ± 6.1 and 62 ± 6.7 y/o respectively (P = 0.224). The number of fusion levels was significant less in LT group (8.00 vs. 13.43, P < 0.001). Operative time and estimated blood loss were slightly higher in the UT group with no significant difference. The prevalence of PJK rate at last follow up was 21.1% in LT group and 45.4% in UT group (P = 0.04). Compared with LT group, patients in UT group had a significant larger PJA at last follow up (15.29 ± 8.25 vs. 6.92 ± 4.33, P = 0.003). Patients in both two groups showed no difference in cervical and spino-pelvic sagittal parameters except for TK before surgery (30.71 ± 15.9 in UT group and 16.77 ± 12.2 in LT group, P = 0.017). At the last follow up, no significant difference in cervical sagittal parameters was observed meanwhile patients in LT group showed worse global sagittal alignment (C7-SVA 16.35 vs 47.52, P = 0.034). Conclusion: Both UT and LT UIVs improve the segmental and global sagittal plane alignment after surgery. The prevalence of PJK was higher in UT group in our study. The alignment of unfused levels, including thoracic profile and cervical alignment was similar between short instrumentation and long fusion in degenerative lumbar scoliosis patients.

P097 - Evolution of Sagittal Plane Correction Durability and Associations with Patient Reported Outcome Measures (PROMS) for Long Fusions Terminating at the Upper Thoracic (UT) vs. Thoracolumbar (TL) Spine with Minimum 3 yr Follow-Up

Munish Gupta¹, Renaud Lafage², Michael Kelly¹, Christopher Shaffrey³, Gregory Mundis⁴, Richard Hostin⁵, Douglas Burton⁶, Christopher Ames⁷, Frank Schwab⁸, Han Jo Kim², Eric Klineberg⁹, Shay Bess¹⁰, Justin Smith³, Virginie LaFage⁸, International Spine Study Group¹¹

¹Department of Orthopaedic Surgery, Washington University School of Medicine, St. Louis - United States

²Hospital for Special Surgery, New York, NY - United States

³Neurosurgery, University of Virginia Medical Center, Charlottesville, VA - United States

⁴Scripps Clinic, Sharp Memorial, Scripps Green, Scripps Memorial, La Jolla, CA - United States

⁵Baylor Scoliosis Center, Baylor Regional Medical Center, Plano, TX - United States ⁶University of Kansas Medical Center, Sharp Memorial, Kansas City, KS - United States ⁷Neurosurgery University of California San Francisco Medical Center, San Francisco, CA - United States ⁸Orthopaedic Surgery, Hospital for Special Surgery, New York, NY - United States ⁹Orthopedic Surgery, UC Davis, Sacramento, CA - United States

¹⁰Orthopaedic Surgery, Denver International Spine Center/Presbyterian St. Luke’s Medical Center, Denver, CO - United States ¹¹Denver, CO - United States

Introduction: Sagittal plane correction of adult spinal deformity (ASD) patients is challenging to achieve and maintain. The natural history for the general population is to demonstrate increasing sagittal malalignment with age. Purpose: Evaluate the durability of surgical sagittal plane correction at minimum 3 year f/u. Hypothesis: Initial sagittal plane correction may degrade following initial surgical correction of sagittal malalignment and this degradation will impace PROMS. Material and Methods: Observational cohort study in a multicenter adult spinal deformity database. Inclusion criteria: age≥18, PI-LL mismatch >10, PT>20, SVA >5 cm and Cobb >20. Patients requiring revision surgery were excluded. Patients divided according to UIV (UT vs. TL) and all patients had fusion to pelvis. Radiographic parameters between UT and TL groups and PROMS evaluated at ≥3 year f/u. Results: 115 pts out of 248 pts (mean: age 62 years, BMI 27) met inclusion criteria, mean f/u 46 months. SRS-Schwab deformity; Neutral = 26, Thoracic = 2, Lumbar = 58, Double = 29. Mean preop SVA = 7.5 cm, PI-LL = 19, PT = 25. In the UT (n = 37) group the SVA, PT, TPA, PI-LL, and UIV-PA improved between baseline and each FU. Thoracic kyphosis (TK) increased from baseline to each FU. Between 6Y and last FU roughly half the patients had TK increase or LL decrease > 5°. In the TL group (n = 44) the SVA, PI-LL, and UIV-PA improved from baseline to each FU. PT improved from baseline to 6wks. TPA improved between baseline, 6wks and 1 yr. TK increases between baseline and each FU. 25% of pts lost > 5° of LL. ODI and SF-36 PCS did not change between baseline and 6 W but improved at 1Y and last FU. The SRS-22 improved at 6wks, had greater improvement at 1Y and remained stable at last FU. Conclusion: Sagittal alignment was improved in all parameters from baseline to 6 W, 1Y and final f/u. There was a gradual increase in thoracic kyphosis in all pts with associated degradation of initial correction in a subset of pts in the instrumented and non-instrumented thoracic spine and instrumented portion of the lumbar spine. All patients demonstrated improvements in PROMS that remained stable over time.

P099 - Defining A Core Outcome Set For Adult Spinal Deformity Surgery – An International Delphi Study Of The Scoliosis Research Society

Sayf Faraj¹, Miranda van Hooff², Tsjitske Haanstra¹, Virginie Lafage³, Anna Wright⁴, David Polly⁵, Steven Glassman⁶, Marinus de Kleuver¹

¹Department of Orthopedics, Radboud University Medical Center, Nijmegen - Netherlands ²Department of Research, Sint Maartenskliniek, Nijmegen - Netherlands ³Department of Orthopaedic Surgery, Hospital for Special Surgery, New York - United States ⁴Neuroscience Institute, Virginia Mason Medical Center, Seattle - United States ⁵Department of Orthopaedic Surgery, University of Minnesota, Minneapolis - United States ⁶Department of Orthopaedic Surgery, University of Louisville, Louisville - United States

Introduction: Adult Spinal Deformity (ASD) causes severe functional disability, reducing the overall quality of life. In view of the growing ASD population, routine monitoring of outcomes covering the overall quality of life, functioning, and disability from a patient’s perspective, will play an important role in future reimbursement and healthcare delivery. In this era of value based care, healthcare providers are putting more emphasis into assessing the value (health gain per unit cost) of treatment provided. In particular for ASD surgery, where a tremendous treatment variability exists, outcome monitoring by means of outcome registries would be of value. Notable, outcome registries are most valuable if they are comparable between countries and include outcomes that are relevant to the patient population of interest. There is need for a standardized approach of outcome reporting in ASD surgery. The aim of this study is to reach international consensus on a core outcome set for ASD surgery. Material and Methods: This study ultimately consists of three phases: 1) Informed by a literature review, to identify potentially relevant outcome measurement instrument selection and reported outcome domains in ASD surgery, 29 outcome domains were classified within the World Health Organization’s International Classification of Functioning, Disability and Health (ICF). 2) A modified Delphi study is performed among a panel of 25 international ASD professionals from the Scoliosis Research Society. In six consecutive online rounds, panellists are asked to select outcome domains, contributing risk and casemix factors, and accompanied measurement instruments that should be included in a core outcome set for ASD surgery. Consensus was defined as 75% or more agreement. 3) Validation with an international patient focus group. Results: Phase 1. The literature review is completed.¹ Phase 2 will be completed in March 2018. In online round 1, panellists reached consensus to include the following ICF outcome domains in a core outcome set for ASD surgery: “sensation of pain (100%)”, “walking (92%)”, and “carrying out daily routine (88%)”. Conclusion: For each core outcome domain, one or more measurement instruments can be suggested for clinical research and practise, selecting among those that are most frequently used and recommended, and that have satisfactory measurement properties in patients with ASD. After final consensus on outcome domains to include in the core outcome set, consensus will be reached on measurement instruments (patient-reported and clinician-based) to measure the derived core set of outcome domains. The development of this core outcome set for ASD surgery will facilitate comparisons across studies, registries, and nations in order to improve the quality of daily clinical practice in this increasing group of patients. We will present the core outcome set (the results of phase 2) at the conference.

Reference

1. Faraj SSA, van Hooff ML, Holewijn RM, Polly DW, Haanstra TM, de Kleuver M. Measuring outcomes in adult spinal deformity surgery: a systematic review to identify current strengths, weaknesses and gaps in patient-reported outcome measures. Eur Spine J 2017; 26: 2084-93.

P100 - Evaluating The Predictive Ability Of Visual Analogue Scale On Oswestry Disability Index And Surgical Treatment Decision In Patients With Adult Spinal Deformity

Prashant Adhikari¹, Vugar Nabiyev¹, Selim Ayhan¹, Selcen Yuksel¹, Alba Vila-Casademunt², Ibrahim Obeid³, Francisco JS Perez Grueso⁴, Ferran Pellise⁵, Frank Kleinstuck⁶, Ahmet Alanay⁷, Emre Acaroglu¹, European Spine Study Group (ESSG)⁸

¹ARTES Spine Center, Ankara - Turkey ²Spine Research Unit, Vall Hebron Institute of Research (VHIR), Barcelona - Spain ³Pellegrin Bordeaux University Hospital, Bordeaux - France ⁴Hospital Universitario La, Madrid - Spain ⁵Hospital Universitari Vall Hebron, Barcelona - Spain ⁶Spine Center, Schulthess Klinik, Zürich - Switzerland ⁷Acibadem Mehmet Ali Aydinlas University, Istanbul - Turkey ⁸European Spine Study Group (ESSG), Uster-Zürich - Switzerland

Introduction: Back pain treatment depends upon patient’s answers to health related quality-of-life (HRQOL) questionnaires to assess the treatment effect. The Visual Analogue Scale (VAS) represents the method of assessments of a feeling. The Oswestry Low Back Pain Disability Index (ODI) was developed in a specialist referral clinic for patients with chronic low back pain (LBP). Self-assessment pain and disability scales correlate with pain and disability better than objective measures of physical performance, which have been reported to have even weaker correlations with self-assessment scales than those between the self-assessments. Indeed, disability scales have been shown to correlate with disability better than scales that measure the intensity of pain, radiographs, MRI, and CT scans. The aim of the current study is to determine whether there is a correlation between preoperative and postoperative ODI and VAS scores in patients with adult spinal deformity (ASD) and try to find out any effect of baseline VAS score for clinical and surgical outcomes. Material and Methods: Prospectively collected data from a multicentric ASD database was analyzed and all surgical patients with a follow-up of 2 years were included and analyzed for demographic, clinical, radiological and health related quality of life (HRQOL) parameters. A univariate binary logistic regression model was performed by using dependent and independent variables. According to distribution shape, Pearson or Spearman correlation coefficient was used to evaluate the correlation between ODI and VAS. Results: A total of 1,050 patients (887F, 163 M) with a mean age of 48.22years were analyzed. The correlation between baseline ODI and baseline back pain (BP) and leg pain (LP) VAS scores were found as statistically significant (p < 0.001). Univariate logistic regression test results for BP and LP VAS scores to evaluate the effect on improvement of ODI for surgically treated (352/1050) patients showed that one unit increment on baseline BP and LP VAS score increases the probability of improvement of ODI by 1.219 times (p = 0.016) and by 1.182 times (p = 0.029), respectively. However, one unit increment on baseline BP VAS score decreases the probability of improvement of ODI by 0.894 times (p = 0.012), and baseline LP VAS score has no effect on improvement of ODI in non-surgical patients. While making the decision on surgical treatment, the overall patient’s univariate logistic regression model showed that one unit increment of baseline BP, LP VAS and ODI scores increases the probability of deciding surgical treatment by 1.159 times (p < 0.001), 1.137 times (p < 0.001) and by 1.037 times (p < 0.001), respectively. Conclusion: This study has demonstrated that there is a correlation between baseline ODI and baseline VAS (BP and LP) scores in patients with ASD. Baseline VAS scores were not found to be associated with lower rates of HRQOL improvement. In fact, baseline VAS (BP and LP) scores were positive prognostic indicators of ODI in surgically treated patients. Further, it appears that all three HRQOL parameters specifically evaluated in this study had significant effects on treating physician’s decision making.

P101 - Outcomes Of Single-Stage Through Fracture Osteotomy And Instrumentation In Patients With Ankylosing Spondylitis

Angus Kaye¹, Sujay Dheerendra², Anthony Amato-Watkins¹, Prokopis Annis¹, Marcus DeMatas¹

¹Royal Liverpool University Hospital, Liverpool - United Kingdom ²Centre for Spinal Studies, The Robert Jones and Agnes Hunt Orthopaedic Hospital, Oswestry - United Kingdom

Introduction: Patients with ankylosing spondylitis have an incidence of spinal fractures four times that of the general population, along with increased mortality (18-32%) and neurological compromise. Traditionally if these patients require deformity correction especially pre-existing, it is performed as a two-stage procedure. We propose that single-stage posterior instrumentation and through fracture osteotomy is a safe alternative to a two-stage procedure in patients with ankylosing spondylitis and an unstable spinal fracture with deformity. Materials and Methods: All patients within our unit who had undergone single-stage through fracture osteotomy and instrumentation and who had a diagnosis of ankylosing spondylitis were included. Four patients were identified; there were no exclusions. Patients’ paper and electronic notes along with radiological imaging was reviewed, in addition to intraoperative neurophysiological monitoring reports. SVA and deformity at the level of the fracture was measured before and after surgery. SVA was also measured from pre-injury imaging if available. Long-term self-reported outcomes were derived retrospectively from clinic letters. Results: Patients’ paper and electronic notes along with radiological imaging was reviewed, in addition to intraoperative neurophysiological monitoring reports. Sagittal vertical axis (SVA) and deformity at the level of the fracture was measured before and after surgery. SVA was also measured from pre-injury imaging if available. Long-term self-reported outcomes were derived retrospectively from clinic letters. Conclusions: Single-stage posterior instrumentation with through fracture osteotomy using intra-operative neurophysiological monitoring is a safe surgical alternative for unstable spinal fractures in patients with ankylosing spondylitis. Early surgical treatment of these patients allows early mobilisation, as these patients are prone to respiratory complications.

P102 - Intraoperative Spinal Cord Monitoring Changes During 3 Column Osteotomies For Kyphosis Correction

Yuen Chan¹, Michael Owen¹, Sujay Dheerendra², Prokopis Annis¹, Marcus DeMatas¹

¹Royal Liverpool University Hospital, Liverpool - United Kingdom ²Centre for Spinal Studies, The Robert Jones and Agnes Hunt Orthopaedic Hospital, Oswestry - United Kingdom

Background: Kyphosis and junctional kyphosis associated with previous surgery commonly present with worsening pain and neurological deficits. The indications for surgery are increasing axial back pain, pseudoarthrosis or malunion that fails to respond to non-operative treatment, and progressive neurological deterioration. Spinal deformity corrections are associated with iatrogenic neurological injuries. Intraoperative monitoring (IOM) is mandatory during spinal deformity correction to alert the surgeon during critical times in these high-risk procedures, allowing modification of surgical technique. These modifications in surgical technique are essential in reducing the occurrence of permanent neurological deficit. The aim of the study was to review the neuromonitoring changes and actions taken to maintain neurological function intraoperatively in kyphosis correction associated with 3 column osteotomies. Materials and Methods: All patients undergoing spinal osteotomy for post-traumatic kyphosis or junctional failure correction using IOM with transcranial MEPs (motor evoked potentials), SSEPs (somatosensory evoked potentials) and frEMG (free running electromyography) were included in the study (n = 11). All IOM reports, demographic details, electronic notes and radiographs for each patient were assessed. Results: There were five posttraumatic kyphosis, two kyphosis deformities through fracture in ankylosing spondylitis, two proximal junctional failures and two distal junctional failures. There were eight females and three males. The median age was 59 years and the average follow-up was 14 months. At latest follow-up, 81% of the patients were pain-free and had no issues. Four patients had neuromonitoring changes. One patient had changes during positioning. The monitoring improved after we repositioned the patient. Two patients had changes during the osteotomy. We responded by checking the level of anaesthesia and increasing the blood pressure (BP). We completed the osteotomy with cage insertion. Both SSEPs and MEPs improved. Another patient had changes during osteotomy closure. We responded by increasing BP and neuromonitoring returned to normal. One patient had a vascular complication intraoperatively. We inserted temporary rods and placed posterior drains. The patient underwent vascular embolization. SSEPs and MEPs return to normal post-stabilization and embolization. Two patients had observed neurology in the immediate postoperative period. No patient had lasting neurological deficits. Conclusions: Observed neuromonitoring changes usually do not result in permanent neurological deficits. In response to the neuromonitoring changes, appropriate alterations were made in surgical technique intraoperatively. Neurological monitoring is mandatory in deformity correction to prevent neurological deficit and facilitate complex deformity correction.

P103 - Do Postoperative Low Hemoglobin Levels Impact Hospital Readmission After Adult Spinal Deformity Surgery?

Vugar Nabiyev¹, Prashant Adhikari¹, Selim Ayhan², Selcen Yuksel³, Alba Vila-Casademunt⁴, Ibrahim Obeid⁵, Francisco Sanchez Perez-Grueso⁶, Ferran Pellise⁷, Frank Kleinstück⁸, Ahmet Alanay², Emre Acaroglu¹, European Spine Study Group (ESSG)

¹ARTES Spine Center, Ankara - Turkey ²Acibadem University School of Medicine, Department of Orthopaedics and Traumatology, Istanbul - Turkey ³Yildirim Beyazit University, Department of Statistics, Ankara - Turkey ⁴Vall d’Hebron Research Institute, Barcelona - Spain ⁵Bordeaux University Hospital, Bordeaux - France ⁶Hospital Universitario La Paz, Madrid - Spain ⁷Hospital Universitari Vall d’Hebron, Barcelona - Spain ⁸Schultess Clinic, Zurich - Switzerland

Introduction: Spinal deformity surgery is associated with significant blood loss and often results in postoperative anemia. Anemia could affect functional recovery after major surgeries by decreasing postoperative endurance and quality of life (QOL). The aim of this study is to evaluate the impact of anemia at the time of discharge from hospital on the functional outcomes, QOL and hospital readmission for any cause after spinal deformity surgery. Material and Methods: Study was conducted on an adult spinal deformity (ASD) population from a multi-center database. Anemia severity was defined in accordance with the 2011 World Health Organization (WHO) guidelines. All patients had health-related quality of life (HRQOL) tests as well as complete blood counts preoperatively. Operative variables included length of surgery, number of surgical levels, fusion intervention, estimated blood loss and the technique (minimally invasive or open) had been used. Perioperative data included length of intensive care unit (ICU) stay and total length of hospital stay. Early readmission, that is, the admission within 30 days of discharge, was used as the dependent parameter because as more time elapses between readmission and discharge, the less likely the association between them. We hypothesised that it is plausible that anemia at discharge would impact readmission within 30 days postoperatively. Results: This study comprised 225 surgically treated ASD patients with a mean age of 62 years, predominantly women (80%). Patients were operated mainly for adult idiopathic deformity (45.8%), degenerative, and other diagnoses (36.9 and 16.9%, respectively). Of the 225 patients, 82(36.4%) had mild, 137(60.9%) had moderate and 7(2.7%) had severe anemia according to WHO classification at the time of discharge. Of those, 25 patients [(mild: 11(64.7%), moderate: 5(29.4%) and severe: 1(5.9%)] were readmitted within 30 days. Interestingly, the mean Hb values were found to be higher in readmitted patients (p = 0.071). Infection was the leading cause of readmission (n = 12), followed by motor deficit (n = 6), severe back pain (n = 3), pleural effusion (n = 1), hematoma (n = 1), calf muscle pain (n = 1), and pain because of screw failure (n = 1). Conclusion: This study has demonstrated that the occurrence and severity of anemia is not associated with early hospital readmissions in surgically treated patients with ASD. These findings may suggest that clinical awareness of the parameters other than anemia could be more important while evaluating the patients after ASD surgery at the time of early readmission.

P104 - A Feasibility Study Of The Bony Cage Rather Than Titanium Mesh In Posterior Vertebral Column Decancellation For The Management Of Pott′S Sharp Kyphosis Deformity

Guoquan Zheng¹, Zhijun Xin², Jingming Wang¹, Xuesong Zhang¹, Yan Wang¹

¹Department of Orthopaedics, Chinese People’s Liberation Army General Hospital (301 Hospital), Beijing - China ²Department of Spinal Surgery, Affiliated Hospital of Zunyi Medical College, Zunyi - China

Introduction: To explore the safety and effectiveness of bony cage rather than titanium mesh in posterior vertebral column decancellation (PVCD) in the management of Pott′s sharp kyphosis deformity. Materials and Methods: Prospective analysis of 26 patients with Pott′s deformity underwent PVCD from August 2010 to May 2014, with a minimum follow-up of 1 year and a maximum follow-up of 5 years. There were 11 males and 15 females with an average age of 24.8 ± 7.6 years old. Among them, the number of apical vertebrae located in thoracic region, thoracolumbar region and lumbar region was 6, 18 and 2, respectively. 1 patient was in grade C, 4 patients were in grade D and 21 patients were in grade E according to ASIA scale. The perioperative data were recorded, which included preoperative Cobb angle, postoperative Cobb angle, final follow-up Cobb angle, apical vertebrae, the length difference of anterior column and posterior column, operation time, perioperative blood loss and complications. Results: The average operation time was 306.2 ± 59.5mins. The average blood loss was 2046.2 ± 742.4 ml. Complications were noted in 5 patients. 2 cases were complicated with transient neurological deficits and 3 cases with cerebrospinal fluid (CSF) leak. The kyphosis Cobb angle decreased from 91.3° ± 17.5° to 17.1° ± 6.2°, with a correction rate of (80.9 ± 6.6)%. The average time of follow-up was 30.8 ± 16.5 months. The Cobb angle was 20.3° ± 6.1°, and the loss of correction was 3% in the final follow-up. The anterior column increased by 3.6 ± 3.1 cm while posterior column shortened by 2.7 ± 1.1 cm. Among 5 patients with preoperative neurological deficit, one patient with ASIA C improved to ASIA D, 3 patients improved from ASIA D to ASIA E, one patient with ASIA D did not recover in the last follow-up. Conclusions: PVCD without using conventional titanium mesh is a safe and effective option for Pott′s deformity.

Keywords: Pott's deformity; Kyphosis; Vertebral column decancellation; Bony cage

P105 - Non-Neurologic Adverse Events After Complex Adult Spinal Deformity Surgery: Results From The Prospective, Multicenter Scoli-Risk-1 Study

Kenny Yat Hong Kwan¹, Cora Bow¹, Dino Samartzis¹, Lawrence Lenke², Christopher Shaffrey³, Leah Carreon⁴, Benny Dahl⁵, Michael Fehlings⁶, Christopher Ames⁷, Oheneba Boachie-Adjei⁸, Mark Dekutoski⁹, Khaled Kebaish¹⁰, Stephen Lewis¹, Yukihiro Matsuyama¹¹, Hossein Mehdian¹², Ferran Pellise¹³, Yong Qiu¹⁴, Frank Schwab¹⁵, Kenneth Cheung¹

¹Department of Orthopaedics and Traumatology, The University of Hong Kong - Hong Kong ²The Spine Hospital, Columbia University, New York - United States ³University of Virginia, Charlottesville - United States ⁴Norton Leatherman Spine Center, Louisville - United States ⁵Texas Children’s Hospital, Fannin - United States ⁶Division of Neurosurgery, University of Toronto, Toronto - Canada ⁷Department of Neurological Surgery, UCSF, San Francisco - United States ⁸The FOCOS Hospital, Accra - Ghana ⁹The CORE Institute, Phoenix - United States ¹⁰Johns Hopkins University, Baltimore - United States ¹¹Hamamatsu University School of Medicine, Hamamatsu - United States ¹²Queen’s Medical Centre, Nottingham - United Kingdom ¹³Hospital Universitari Vall d’Hebron, Barcelona - Spain ¹⁴Nanjing University Medical School, Nanjing - China ¹⁵Hospital for Special Surgery, New York - United States

Introduction: Most studies reporting on complications of complex adult spinal deformities (ASD) surgeries were retrospective in nature without clearly-defined inclusion criteria or validated assessment, and none had specifically focused on non-neurologic adverse events. The purpose of the present study was to investigate the rate and types of non-neurologic adverse events after surgical correction of complex ASD, and to identify risk factors that affect their occurrence, based on a prospective, multicenter study. Material and Methods: The demographic data, medical and surgical details, and occurrence of all non-neurologic adverse events were reviewed in a prospective cohort of 272 patients who had undergone corrective surgeries for complex ASD and enrolled in a multicentre database of the Scoli-RISK-1 study with a minimum follow-up of 2 years. Results: There were 515 non-neurologic adverse events in 184 patients, giving an incidence of 67.6%. 121 (44.5%) patients suffered from more than one adverse event. 300 (58.3%) adverse events occurred within 6 weeks of surgery, and 215 (41.7%) occurred 6 weeks postoperatively. The most frequent non-neurologic adverse events were surgically-related (27.6%), of which implant failure and dural tear were most common. Conclusion: The incidence of non-neurologic adverse events for patients undergoing corrective surgeries for ASD found was 67.6%. These findings complete the earlier report of neurologic complications after ASD surgeries from the Scoli-RISK-1 study. Spinal surgeons now have a full understanding of the comprehensive risk profile for patients undergoing such surgeries.

P106 - Acute Normovolemic Hemodilution In Spinal Deformity Surgery

Emiliano Vialle¹, Marianna Batista², Joana Guasque¹, Caroline Costa², Joana Fiorentin³, Camila Souza³

¹Department of Orthopaedics, Spine Unit, Hospital Universitário Cajuru, Curitiba - Brazil

²Department of Orthopaedics, Hospital Universitário Cajuru, Curitiba - Brazil ³Department of Anesthesiology, Hospital Universitário Cajuru, Curitiba - Brazil

Introduction: To prospectively compare clinical and laboratorial aspects of patients undergoing spine deformity surgery using acute normovolemic hemodilution technique with tranexamic acid against control group with tranexamic acid only. Evaluate the influence of hemodilution in intraoperative bleeding and need of homologous transfusion. Material and Methods: Comparative prospective study between acute normovolemic hemodilution technique associated to tranexamic acid and tranexamic acid only (15 mg/kg) in patients undergoing spine deformity surgery. Age range between 12 to 65 years. Laboratorial exams were analysed in three different moments. Results: 30 patients were included in the present study, with 17 being part of the hemodilution group and 13 of the control group. Average duration of surgery in the hemodilution group was longer. The range of number of levels submitted to surgery varied between 7 and 16 to the hemodilution group against 4 to 13 to the control group. There was more intraoperative bleeding in the control group. All patients were stable during the procedures. Only 6 participants needed homologous blood transfusion, mostly of the control group (p > 0.05). Conclusion: There was no significant difference between the two groups in the need of blood transfusion and intraoperative bleeding. The severity of the deformity was the main determinant of homologous blood transfusion.

P107 - Sagittal Alignment In Patients With Post-Traumatic Kyphosis Before And After Corrective Osteotomy

Oscar Bravo², Manuel Valencia^1,3, Alvaro Silva³, Felipe Novoa^1,3, Guillermo Izquierdo⁴, Javiera Valencia⁵

¹Spine Surgery Team, Traumatology Department, Hospital Mutual de Seguridad, Santiago - Chile ²Traumatology Resident, Universidad de Valparaíso - Hospital Mutual de Seguridad, Santiago - Chile ³Spine Surgery Team, Traumatology and Orthopedics Department, Clínica Alemana, Santiago - Chile ⁴Spine Fellow, Spine Surgery Team, Traumatology and Orthopedics Department, Clínica Alemana - Universidad del Desarrollo, Santiago - Chile ⁵Medicine Student, Universidad del Desarrollo, Santiago - Chile

Introduction: Post-traumatic kyphosis occurs after inadequate diagnosis and treatment of spinal fractures leading to a painful and incapacitating condition. Some reasons for this are the compensatory mechanisms to maintain sagittal balance such as decrease of thoracic kyphosis and/or lumbar hyper-lordosis. Persistent pain and disability refractory to conservative treatment is an indication for surgical correction of these deformities. The aim of this study is to compare sagittal alignment and compensatory mechanisms variations of the spinal and pelvic segments before and after corrective osteotomy in patients with posttraumatic kyphosis. Methods: Retrospective analysis of standing lateral full spine X ray pre and post corrective osteotomy of patients with post-traumatic deformity. Regional kyphosis (RK), thoracic kyphosis (TK), lumbar lordosis (LL), lower lumbar lordosis (LLL), lumbar lordosis distal to instrumentation (LLDI), pelvic incidence (PI), pelvic tilt (PT) and sagittal vertical axis (SVA) were measured. Additionally spinopelvic harmony (SPH) was established according to SVA, PT, PI and LL values. Wilcoxon test was used to establish statistical differences. Results: Lateral full spine X rays of 16 patients, 14 males and 2 female with post-traumatic kyphosis treated with corrective osteotomies were analyzed. The surgical correction was performed within a median time of 7 months after the fracture diagnosis (2-33 months). The osteotomy was performed at T12 or L1 in 62.5% of the patients. There was significant difference between pre and post correction regional kyphosis (RK), (33.5° vs. 12°, p <0.001) and lumbar lordosis distal to instrumentation (LLDI), (68.5° vs. 61°, p = 0.017). No statistical difference was found in pre and post correction lumbar lordosis (LL) (67º vs. 61º, p = 0.193), lower lumbar lordosis (LLL) (48° vs. 43.5°, p = 0.334), sagittal vertical axis (SVA) (22 mm vs. 16.5 mm, p = 0.571), pelvic tilt (PT) (14.5º VS 14.5º, p = 0.706) and subtraction of lumbar lordosis and pelvic incidence (LL-IP) (15° vs. 9.5°, p = 0.233). Conclusions: Post-traumatic kyphosis leads to a type 1 or compensated imbalance through modification of segmental alignment of the mobile spine adjacent to the deformity, mainly the lower lumbar spine. Other compensatory mechanisms such as pelvic rotation are not significantly involved. Osteotomies are an efficient tool to correct the angular deformity after spinal trauma. Despite no significant statistical change, there is a tendency to reestablish the spinopelvic harmony after post-traumatic kyphosis correction in this group of patients.

P108 - Sagittal Imbalance And Mammary Hypertrophy: Is There Any Relationship Between Symptoms, Extent Of Mammary Hypertrophy And Spinal Sagittal Alignment?

Alvaro Silva¹, Juan José Zamorano¹, Felipe Novoa¹, Bartolome Marré¹, Carolina Avilés¹, Daniela Aguiló|¹, Benjamin Guiloff¹, Guillermo Izquierdo¹, Matías Delgado¹

¹Clinica Alemana - UDD, Santiago - Chile

Introduction: Mammary hypertrophy (MH) can be associated with mechanical back and shoulder pain, as well as submammary intertrigo, all of which may deteriorate the patient’s’ quality of life. Unfortunately these symptoms are usually subjective and an aesthetic focus frequently interferes with the clinical evaluation. Literature describes a relationship between MH and postural dorsal kyphosis, but there are no reports regarding its impact on spinopelvic balance and associated symptoms. The aim of this study is to asses if there is a relationship between the extent of MH, spinopelvic balance and the presence of spinal pain and other symptoms. Materials and Methods: Retrospective review of healthy female patients with MH, with associated musculoskeletal pain, referred for a Spine Surgery consult by Plastic Surgery during preoperative assessment for a reduction mammoplasty, between 2014 and 2017. MH was defined as a distance from the suprasternal notch to the nipple of over 26 cm. We excluded patients with a body mass index (BMI) greater than 28 kg/m² or under 19, with previous spine problems, skeletal deformity or pathology, structural spine injury, pregnancy or decompensated psychosis. Demographics and images were reviewed, statistical analysis with logistic regression and t-test, using SPSS program. An alpha value <0.05 was used. Results: 35 patients, mean age 36.7 years (SD� ± 13.5), mean BMI was 24.0 kg/m² (SD ± 3.5). Prevalence of symptoms: trapezius pain 73.5%, back pain 88.2%, low back pain 91.1%, mechanical low back pain with extension 61.7%, breast pain with physical activity 38.2%. Distribution of spinopelvic parameters: mean dorsal kyphosis 43.0º (SD ± 10.2), lumbar lordosis 54.9º (SD ± 13.6), pelvic incidence (PI) 49.8º (SD ± 11.9), sacral slope 38.0º (SD ± 9.1), pelvic tilt 11.7º (SD ± 7.1), sagittal vertical axis -6.7 mm (SD ± 23.6). There was a significant relationship between breast volume and BMI. There was no association between sagittal balance and age or BMI. There is a tendency for a significant association between breast volume and lumbar, dorsal and trapezius pain, hyperlordosis and protraction of the head (p = 0.05). 56.25% of patients presented negative spinal imbalance. Patients with negative sagittal balance had a significantly higher frequency of breast pain with physical activity and greater mechanical low back pain with extension (p = 0.011). Negative sagittal balance was significantly associated with hyperlordosis (p = 0.01). Patients with low PI have more negative imbalance than patients with high PI (p = 0.02). Conclusion: 91.1% of patients reported low back pain. There is a tendency for a significant association between increased breast volume and musculoskeletal symptoms. 56.25% of patients had negative spine imbalance. Patients with negative spinal imbalance presented significantly greater low back pain with extension, which can be explained by an overload of the facet joints. We found that patients with a low PI had greater negative spine imbalance. This is probably explained because they have a lower pelvic compensation capacity and must compensate with hyperlordosis.

P109 - Staggered Instrumentation In Adults Undergoing Posterior Spinal Fusion: A Novel Technique For Soft Tissue Preservation At The Upper Instrumented Vertebra

Matthew Wilkening¹, Omar Yaldo¹, Jason Meldau², Scott Russo³

¹Spectrum Health, Grand Rapids - United States ²Michigan State University College of Human Medicine, Grand Rapids - United States ³Orthopedic Associates of Michigan, Grand Rapids - United States

Introduction: Proximal junction kyphosis (PJK) and proximal junctional failure are common complications of surgical treatment for adult spinal deformity. The incidence of PJK/PJF is reported at 20-40%; of these cases, about 50% will undergo revision surgery for PJK. Revision surgery for PJK/PJF approximately doubles the cost of surgical treatment for ASD and is estimated at 77 432 US dollars per revision surgery. Risk factors contributing to PJK have been extensively investigated. Both patient specific and modifiable risk factors have been identified. Important modifiable risk factors include implant design, construct design, degree of correction, disruptions of posterior elements, and combined anterior/posterior procedures. Despite known, construct specific, modifiable risk factors, the optimal construct design to prevent PJK remains elusive. Material and Methods: A total of 19 patients (3 men and 16 women) underwent posterior fusion using a unique, staggered technique for pedicle screw-rod construct, whereby the upper instrumented vertebra was varied by either 1 or 2 levels from the contralateral pedicle screw-rod construct. Patients were included if they were older than 18 years old and were undergoing either primary or revision surgery for ASD. Patients with previous surgery for ASD, including those with previous development of PJK were not excluded. Patients undergoing fixation for acute trauma, compression fracture, and neoplastic deformity were excluded. Follow-up ranged from 2 to 28 months. The primary outcome measure was defined as re-operation rate due to proximal junctional kyphosis. Secondary measures included the rate of complications such as PJK not requiring revision, pseudoarthrosis formation, instrumentation failure, infection, and upper instrumentation pain. Results: One patient required revision due to PJK. In this patient, PJK occurred concomitantly with infection and upper instrumentation failure at 23 months post-operatively. One additional patient developed radiographically significant PJK but remains clinically asymptomatic. Two additional patients required reoperation for infection. Minor complications included superficial wound infection (1 patient), temporary motor deficit (2 patients), and upper instrumentation pain (2 patients). The average number of instrumented levels was 9.74 (range 5 to 15). On average, kyphosis at the proximal instrumented vertebrae increased 4.26 degrees (range -8 to 24). 2 patients were lost to follow up. Conclusion: Asymmetric screw rod fixation is a safe technique with the potential to decrease proximal junctional kyphosis, proximal junctional failure, and therefore, revision spine surgery for adult spinal deformity.

P110 - Efficacy And Safety Of High-Dose Tranexamic Acid Protocol In Adult Spinal Deformity – Analysis Of 100 Consecutive Cases

James Lin¹, Jamal Shillingford¹, Joseph Laratta¹, Lee Tan¹, Charla Fischer¹, Lawrence Lenke¹, Ronald Lehman¹

¹Department of Orthopedics, Columbia University Medical Center, New York - United States

Introduction: Spinal deformity surgery is a massive undertaking that may involve a significant amount of blood loss, especially when various osteotomy techniques are utilized as part of the treatment strategy for spinal deformity correction. Blood loss has been identified as an independent risk factor for worse clinical outcome in spine surgery. Antifibrinolytic agents such as tranexamic acid (TXA) have been used in an attempt to reduce intraoperative blood loss. However, there is no universally accepted dosing protocol for use during adult spinal deformity surgery. This study aims to investigate the safety profile and efficacy of using a high-dose TXA protocol during adult spinal deformity surgery. Materials and Methods: Consecutive patients undergoing spinal deformity correction over a 14-month period (September 1st 2015 - November 1st 2016) at a single institution were identified. Inclusion criteria were adults (age ≥ 18 years old) who underwent posterior spinal fusion surgery of at least 5 levels and use of our standard TXA protocol of 50 mg/kg intravenous loading dose followed by a 5 mg/kg/hr infusion until skin closure. Patient demographics, estimated blood time (EBL), operative time, amount of blood transfusion post-operatively, and other procedure specific information were recorded and analyzed. Results: A total of 100 adult patients (≥ 18 years old) were included in the study. Operative procedures were performed by a single surgeon (LGL). The mean age was 46.5 years, and 71% of patients were female. Average BMI was 24.7. The average fusion length was 14 levels. 46/100 patients had a primary surgical procedure while the rest were revisions. 61/100 of patients had pelvic fixation, and 53/100 patient had a TLIF for anterior column support. Posterior column osteotomies were performed on 80/100 patients; pedicle subtraction osteotomy (PSO) was performed in 8 patients; and vertebral column resections (VCRs) were performed in 15 patients. Average operative time was 573.5 minutes. Mean intraoperative blood loss among all patients was 1296 cc. There was one PE was treated with a heparin drip, and two DVTs which developed in rehab which were treated with oral anticoagulation. There were no MIs, seizures, strokes, or renal complications. Conclusion: High-dose TXA protocol is safe and effective in reducing intraoperative blood loss in spinal deformity surgery.

P111 - Restoring Lumbar Lordosis And Balance Of The Spine Without Pso Or Vcr: Multicentric Experience On A Cohort Of 50 Consecutive Adult Degenerative Kyphoscoliosis

Alessandro Ramieri¹, Giuseppe Costanzo², Massimo Miscusi³, Antonino Raco³

¹Don Gnocchi Foundation, Milan - Italy ²Orthopaedics, Sapienza University, Roma - Italy ³Neurosurgery, Sapienza University, Rome - Italy

Introduction: In a multicentric cohort of adult degenerative thoraco-lumbar and lumbar kyphoscoliosis we evaluated the effectiveness and safety of surgery performed without posterior subtraction osteotomy (PSO) or vertebral column resection (VCR). Methods: To restore lumbar lordosis, mobilize and correct coronal curves, we operated 50 consecutive painful thoraco-lumbar and lumbar compensated degenerative deformities by anterior (ALIF), oblique (OLIF), extreme lateral (XLIF) and transforaminal (TLIF) interbody fusion associated to posterior grade 2 osteotomy (SPO). Surgery performed in two stages, first anterior and after 2-3 weeks posterior, was proposed when the Oswestry Disability Index (ODI) was equal to or greater than 50% and VAS more than 5. X-ray full screening was adopted during pre, post-operative and follow-up periods. Results: We performed 10 ALIFs, 22 OLIFs, 59 XLIFs, 35 TLIFs, 62 SPOs. Complication rate was 18% after anterior fusion and 20% after posterior approach, with 2 major complications. All spino-pelvic parameters improved (p < 0.05) and clinical follow-up (mean 23.5; range 18-36) was satisfactory in all cases, except for 2 due to sacro-iliac pain. Mean preoperative VAS was 7.9 (range 6-10), while ODI was 73% on average (range 55-80). Postoperatively, VAS and ODI decreased respectively to 3.5 (range 2-5) and 35% (range 25-55), while their values were 4.3 (range 2-6) and 38% (range 20-55) at the final follow-up. Conclusions: Based on our multicentric experience and current mean 2 years follow-up, the surgical approach adopted in this study to treat adult compensated degenerative sagittal imbalances of the thoraco-lumbar spine seems promising, with a low rate of severe complications and significative improvement of balance and clinical condition.

Keywords: scoliosis, kyphosis, adult degenerative spine, osteotomy, interbody fusion

P112 - The Minimum Invasive Corrective Technique For Adult Spinal Deformity (Asd) By Using Lateral Lumbar Intervertebral Fusion (Llif) & Percutaneous Pedicle Screw (PPS)

Sei Terayama¹, Yasuo Ohori¹, Azusa Sudo¹

¹Sangubashi Spine Surgery Hospital, Tokyo - Japan

Introduction: Senile populations are getting larger in the world wide, so we often encounters senile kyphoscoliosis patients due to ASD. Recently, minimum invasive spine surgery (MIS) techniques developed greatly and it is much helpful to reduce total amount of intra-operative blood loss (TBL) and made one-stage operation possible. Material and Methods: The 33 consecutive ASD patients with a global imbalance had the MIS corrective surgeries at the 2 hospitals of our medical corporation from Oct. 2015 to July 2017. They are 5 males and 28 females. The mean age is 76.9 years old and the mean follow-up period is 345 days. All patients were undergone at first LLIF (either XLIF or OLIF) from L1/2 to L4/5 and L5/S1 TLIF, then PPS from L1 to S1, SAI or modified iliac screws, and T10 (9) to T12 PS were all installed through either open method or PPS. As for a thoraco-lumbar level, decortication of lamina & grafting local bone were performed and sublaminar cable were tightened in order to prevent PS from pulling out. Right after LLIF, lumbar lordosis (LL) is nearly same as a pre-operative value measured by Fulucrum-Back-Bending lateral X-ray (FBB-X-ray). While installing an appropriately bent rod, we uses a Cantilever technique and a rod maneuver technique to get an adequate LL. We estimated the anterior & posterior operation time and TBL, the pre- & post-operative values indicating global alignment such as Cobb (Cobb angle), LL, SVA(Sagittal Vertical Axis), PI (Pelvic Incidence), PI-LL. PT (Pelvic Tilt). Results: The anterior & posterior operation time and TBL were 136 mins, 296 mins and 412 g respectively. Each global alignment values were improved postoperatively as follows. Cobb; 26.1 to 4.4, LL; 3.1 to 47.5, SVA; 133 to 10, PI-LL; 47.5 to 4.0, PT; 37.2 to 23.4. Conclusion: All 33 patients gain adequate lumbar lordosis matched with their own PIs, and which are preserved in their daily life. Our MIS technique for ASD by using lateral approach & PPS prevents muscle damage and massive blood loss, which reduces patients’ burden. It gives as a good correction as a full-open posterior surgery, and takes senile ASD patients to a less invasive surgery.

P113 - Human Versus Robot: A Propensity-Matched Analysis Of The Accuracy Of Free Hand Versus Robotic Guidance For Placement Of S2 Alar-Iliac (S2AI) Screws

Jamal Shillingford¹, Joseph Laratta¹, Joseph Lombardi¹, Alex Tuchman¹, Ronald Lehman¹, Lawrence Lenke¹

¹Department of Orthopedics, Columbia University Medical Center, New York - United States

Introduction: Spinopelvic fixation utilizing S2AI screws provides optimal fixation across the lumbosacral junction allowing for solid fusion, especially in long segment fusion constructs. Materials and Methods: The records of 68 consecutive patients who underwent S2AI screw placement by either robotic or free hand technique between 2015-2016 were reviewed. Propensity scores were created after identifying preoperative characteristic imbalances to reduce selection bias. Screw position and accuracy was evaluated using 3D manipulation of intraoperative O-arm imaging. Results: A total of 51 patients (105 screws) were matched, 23 (46 screws) in the robot group (RG) and 28 (59 screws) in the free hand group (FHG). There was one 3-screw and one 4-screw construct in the FHG. The mean age in the RG and FHG were 61.6 ± 12.0 yrs and 57.9 ± 14.6 yrs (p-value = 0.342) respectively. The average caudal angle in the sagittal plane was significantly larger in the RG (31.0 ± 10.0° vs 25.7 ± 8.8°, p-value = 0.005). When comparing the RG to the FHG, there was no difference in the horizontal angle, measured in the axial plane using the PSIS as a reference (42.8 ± 6.6° vs 41.1 ± 8.1°, p-value = 0.225), or the S2AI to S1 screw angle (11.3 ± 9.9° vs 9.4 ± 7.0°, p-value = 0.256), respectively. There was no difference in the overall accuracy rates of the RG and FHG (97.8% vs 94.9%, p-value = 0.630). Additionally, there were no significant intraoperative neurovascular or visceral complications associated with S2AI screw placement. Conclusion: Free hand and robotic-guided S2AI screw placement both prove to be safe and reliable techniques for achieving spinopelvic fixation.

P114 - Unilateral vs. Bilateral Lower Extremity Motor Deficit following Complex Adult Spinal Deformity Surgery: Is there a Difference in Recovery up to 2 Year F/U?

Alex Tuchman¹, Lawrence Lenke¹, Michael Fehlings², Leah Carreon³, Chris Shaffrey⁴, Benny Dahl⁵

¹Department of Orthopedics, Columbia University Medical Center, New York - United States ²Toronto Western Hostpital, Toronto - Canada ³University of Louisville, Louisville - United States ⁴University of Virginia Medical Center, Charlottesville - United States ⁵The Capital Region Of Denmark, Hillerød - Denmark

Introduction: Scoli-RISK-1 is a multicenter prospective cohort designed to study neurologic outcomes following complex adult spinal deformity (ASD). The effect of unilateral versus bilateral post-operative motor deficits on the likelihood of long term recovery has not been previously studied in this population. Methods: Prospective cohort of 273 consecutive patients were enrolled from September 2011 to October 2012. Neurologic decline was defined as deterioration of the American Spinal Injury Association Lower Extremity Motor Scores (LEMS) compared to pre-operative status. Patients with lower extremity neurologic decline were grouped into unilateral and bilateral cohorts. Wilcoxon rank sum test was used to compare the total LEMS and change in total LEMS at 6 week, 6 month, and 24-month time points. Results: 265 patients were included and 61 (23%) displayed decline in LEMS at hospital discharge. Unilateral weakness was seen in 32 patients (12%), while the other 29 (11%) had bilateral symptoms. In both groups the majority of LEMS decline was 5 points or less (unilateral n = 25, 78%; bilateral n = 19, 66%). At 2 years there was no difference in either mean LEMS (unilateral 48.3 ± 2.9; bilateral 47.7 ± 4.7, p = 0.939) or change in LEMS (unilateral -0.9 ± 3.0; bilateral -1.0 ± 3.2, p = 0.920). In both groups approximately two-thirds of patients with initial worsening in motor exam saw recovery to at least their pre-operative baseline by two years post-operatively (unilateral n = 15, 63%; bilateral n = 14, 67%). Conclusion: The prognosis for recovery of new motor deficits following complex adult spinal deformity is similar with both unilateral and bilateral weakness.

P115 - The Superiority Of Multilevel Oblique Lateral Interbody Fusion (MOLIF) Versus Pedicle Subtraction Osteotomy

Lui Darren¹, Hai Ming Yu¹, Susanne Selvadurai¹, Sean Molloy¹

¹Royal National Orthopaedic Hospital, London - United Kingdom

Introduction: Complex Adult Spinal Deformity (CASD) represents a challenging cohort of patients. Restoration of sagittal parameters is associated with good outcome in standard adult spinal deformity (ASD). Pedicle subtraction osteotomies (PSO) is an important technique for sagittal balance in ASD but is associated with significant morbidity. There is a trend towards transpsoas lateral lumbar interbody fusion (LLIF) but they are associated with high postoperative neurological deficit. We have previously shown the efficacy of minimally invasive anterior lumbar interbody fusion (ALIF) using Tantalum cages for restoration of sagittal balance. The technique, Multilevel Oblique Lumbar Interbody Fusion (MOLIF) can address L1/2 to L5/S1 through a single 10 cm incision. We aim to explore the efficacy of MOLIF technique over PSO in the restoration of sagittal balance in stiff or fused CASD only. Materials and Methods: Prospective cohort with retrospective review. 130 Adult Spinal Deformity Patients from a single surgeon series. 130 consecutive patients ASD. 68 patients with CASD only type B & C Silva Classification with 34 patients each Group. Parameters investigated: Pelvic Incidence (PI), segmental lumbar lordosis L4-S1 (SLL), regional lumbar lordosis L1-S1 (RLL), Pelvic Tilt (PT), Sacral Slope (SS), Sagittal vertical alignment (SVA), PI LL mismatch (PI: LL) and SLL PI % mismatch (PI: SLL), Thoracic Kyphosis (TK). Results: Group 1 mean age 62.9 (45-81) and Group 2 66.76 (47-79). SMA: 64.7% female versus PSO 76.5% females. Body Mass Index (BMI) for Group 1(SMA) 28.05 and Group 2 (PSO) 27.17. Preoperative radiographic parameters were equally matched. Mann Whitney U non parametric tests were performed: MOLIF: Cobb (preop 20.3, postop 9.2 p < 0.005); TK (preop 39.2, postop 39.6 p = 0.375); SVA (preop 99.5, postop21.5, p < 0.005); PI (55.1), RLL (preop 34.03, postop 51.1, p < 0.005); SLL (preop 22.6, post op 37.7, p < 0.005); SS (preop 27.3, postop 34.3, p < 0.005), PT (preop 25.9, postop 22.8, p < 0.05); PILL mismatch (preop 21.1, postop 4.15, p < 0.005), SLL PI % mismatch (preop 36.2%, postop 60.3%, p < 0.005). PSO: Cobb (preop 30.14, postop 14.6, p < 0.05); TK (preop 37.1, postop 42.1, p = 0.07); SVA (preop 75.8, postop 66.7, p = 0.29), PI (55.6); RLL (preop 25.8, postop 46.1, p < 0.005), SLL (preop 24.6, postop 31.3, p < 0.05); PT (preop 30.7, postop 25.7, p < 0.005); PILL mismatch (preop 29.6, postop 9.71, p < 0.005); SLL PI % mismatch (preop 45%, postop 57%). Postop: SLL (MOLIF 37.7, PSO 31.3, p < 0.05); Postop SVA (MOLIF 21.53, PSO 66.7, p < 0.05); Postop Cobb (MOLIF 9.2, PSO 14.57, p < 0.05); Postop SS (MOLIF 34.3, PSO 30.6, p < 0.05); Listing C7-CVSL (MOLIF 18.8, PSO 33.4, p < 0.05). Conclusions: MOLIF is as efficacious as PSO in restoration of all spinopelvic parameters but there are some significant superior features namely Segmental Lumbar Lordosis (L4-S1) where the value should approximately 60% of the pelvic incidence, sacral slope, SVA, Listing and Cobb. A PSO for ease is often performed at L3. A PSO can give an acute angular correction versus the more harmonious cadence that multilevel ALIF can deliver even through a MIS MOLIF approach.

P116 - Analysis And Results Of The Global Balance Of The Surgical Treatment Of Adult Spinal Deformities

Amado Gonzzalez Moga¹, Amado Gonzzalez Moga¹, Rene Crisanto Mora Avila²

¹Ortopedia, Ciudad de México - Mexico ²Departamento de columna, Ecatepec - Mexico

Introduction: Adult scoliosis is defined as an abnormal curvature greater than 10° in patients older than 18 years. The curvature in infancy that was not treated progresses into adulthood. Scoliosis occurs in an adult without a history of a curvature in childhood, is classified as degenerative scoliosis of Novo. As we age, there are changes in the spine due to cascaded disc degeneration, spinal narrows, deformity, instability, imbalance, gait alterations and pain as a main symptom. Authors such as Roussoly Pierre, Duval - Beaupare and La Scoliosis Research Societi describe a global spinal balance in determining preoperative planning and its outcomes in corrective surgery. Objective: The purpose and validation of adult spinal deformities classification systems will be to report and treat options and outcomes with adult affection. Material and Methods: Retrospective, descriptive, observational study with a cohort of 42 patients with Adult Spinal Deformity treated surgically from January 2010 to May 2014 at Centro Médico Ecatepec. Study of 42 patients between 55 and 82 years, mean age of 68.5 ( ± 5.5) years, 35 women (83%) and men 7 (17%). with a time of evolution of lumbar pain of 12 months. It included the criteria of the global balance for preoperative analysis with radiographic study AP and Lateral. Magnetic Resonance and CAT were used to analyze the narrowing of the spinal canal. Radiographic controls at 2, 4 and 6 months of follow-up assessing the correction of the deformity and its repercussion with the clinic according to the scale of EVA and Owestry. Results: Sclerosis Double Major 8 cases (DM). Double major curve (DM) + = modified lumbar degeneration of L2-L5; - = modified global and regional sagittal balance. Lumbar scoliosis of the new 16 cases with the following characteristics: A pelvic tilt of 41° and a lumbar lordosis of 55° with an average of 49.5° and a sacral slope < of 35°, modified lumbar degeneration of L2-L5; - = with modified global and regional sagittal balance. Scoliosis of thoracolumbar 12 cases (TL). + = global and regional sagittal balance modified with a Pelvic Incidence angle of 44° lumbosacral angle of 52° and a 35° sacral slope. Sclerosis, triple major 4 (TM) with inflection point in L3-L4.With upper limb apex L5 with thoraco-lumbar kyphosis and short lumbar lordosis with small pelvic incidence (PF) and pelvic tilt (PT) 3.9 ± 4. Scoliosis Primary Deformity in the sagittal plane 2 cases (SP) with imbalance in the sagittal plane with pelvic tilt of 63° lumbosacral angle 71 and a 45° sacral slope. The EVA Scale and an Owestry were considered at 2, 4.6-12 months follow-up. Conclusions: Adult Spinal Deformities provide reports of surgical treatment showing more reliable results and contribute to development and evidence based on care and treatment with long-term research.

Degenerative Cervical

P117 - Cervical Intradural Disc Herniation After Percutaneous Endoscopic Cervical Discectomy

Young Joon Rho¹

¹Nam Ki Se Spine and Joint Hospital, Seoul - Korea, Republic

Introduction: Cervical intradural disc herniation (IDH) is an extraordinarily rare condition, including only 0.27% of all disc herniations. This study aimed to report an unusual case of cervical IDH after percutaneous endoscopic cervical discectomy (PECD) and discuss difficulties in preoperative diagnosis with considering the possibility of IDH in patient with previous surgery. Material and Methods: 72-year-old woman presented with left arm radiculopathy. She had undergone PECD at left C5-6 and C6-7 level 18 months ago. The magnetic resonance imaging (MRI) of cervical spine revealed large, paracentral disc herniations at C6-7 that caused severe spinal cord compression and surrounding edema. The patient underwent decompression through an anterior cervical discectomy and fusion. Results: The patient's left arm pain improved rapidly 1 day postoperatively, but hand grasp muscle decreased 4/5 strength in the left side. The hand weakness fully recovered 1 month after operation. Conclusion: We presented an extremely rare case of cervical IDH after PECD. The potential presence of an IDH must always be considered preoperatively in patients who had a history of previous surgery. Furthermore the existence of ‘‘hawk-beak sign’’ on axial imaging as well as abrupt loss of continuity of the posterior longitudinal ligament (PLL) on MRI study are helpful for diagnosing IDH.

P118 - A Study Of Functional Outcome Of Anterior Decompression And Fusion In Cervical Myelopathy

Srinath P¹, Ravi V²

¹Department of Orthopedics, Apollo Hospitals, Chennai - India ²Department of Spine Surgery, Apollo Hospitals, 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. 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. Anterior and posterior approaches are associated with their own advantages and disadvantages. Yet outcome comparisons have not demonstrated a conclusive superiority of any approach. We assessed and are presenting the safety and efficacy of anterior cervical decompression techniques in patients with symptomatic myelopathy based on functional scoring systems. Material and Methods: The present study is done in the Department of Orthopaedics Apollo hospitals, Chennai from 2013-2016. During the study 152 patients who underwent cervical decompression for cervical myelopathy using anterior techniques were studied prospectively.

Inclusion criteria:

• Multiple level up to 4.

• Both degenerative myelopathy and ossified posterior longitudinal ligament (OPLL) cases.

• All anterior cervical decompression and fusion (ACDF), anterior cervical corpectomy and fusion (ACCF) and hybrid.

• All age groups which fall In to the diagnosis.

Exclusion criteria:

• Elderly age groups with significant comorbidities.

Follow up: All the patients were followed at 6 weeks, 12 weeks, 6 months to record their functional status and compared with Nurick Grading and modified Japanese Orthopaedic Association (JOA) Score. Results: We have conducted study on 152 patients. The age group of the patients ranged between 29-85years. The most commonly involved level is C5-C6 (60%). 70% of cases were due to cervical spondylotic myelopathy (CSM), 30% were due to OPLL. ACDF was performed in 124 patients and ACCF in 26 patients, disc replacement in 2 patients. The average blood loss was 79.1 ml, operative time 111.43 min and duration of hospital stay was 3.2 days. The functional Nurick score improved from mean of 2.26 pre operatively to 1.53 at follow up and the JOA score improved from a mean of 11.25 pre operative to 13.67 at 24 weeks follow up. Age and duration of symptoms did not play a role in influencing the functional status. Complications were observed in 4 patients – 1 patient had superficial infection and 3 patients had intraoperative dural tear which were repaired. Conclusion: Anterior decompression technique is an effective and safe method of management in symptomatic cervical myelopathy. Anterior decompression and fusion 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. Implant related complications and less. 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.

P119 - Comorbid Conditions As Predictors Of Postoperative Outcome Following Cervical Spine Surgery: A Survey Of United States Orthopaedic And Neurological Surgeons

Heath Gould¹, Jeffrey O’Donnell¹, Vincent Alentado², Colin Haines³, Jason Savage¹, Thomas Mroz¹

¹Cleveland Clinic, Cleveland, OH - United States ²Indiana University, Indianapolis, IN - United States ³Virginia Spine Institute, Reston, VA - United States

Introduction: The direct relationship between comorbid conditions and postoperative outcome following cervical spine surgery has not been well described. Although some clinical data have been presented, there remains a lack of consensus among surgeons regarding the value of common comorbidities as predictors of poor postoperative outcome. The present study seeks to better characterize this discordance by eliciting surgeons’ beliefs in the form of a nationally-distributed survey. Methods: An electronic survey was distributed to orthopaedic and neurological surgeons throughout the United States. In addition to providing demographic information, respondents were asked to rate the value of five comorbidities as predictors of poor postoperative outcome following cervical spine surgery. The following comorbidities were surveyed: history of smoking, chronic narcotic use, diabetes, obesity, and psychosocial complication (e.g. depression, anxiety). Study participants recorded their responses using a 5-point Likert scale that ranged from 1 – “very weak predictor” to 5 – “very strong predictor”. Results: 247 surgeons completed the survey, including 189 orthopaedic surgeons (76.5%) and 58 neurological surgeons (23.5%). All major U.S. geographical regions were represented. Psychosocial complication (4.04 ± 0.87) and chronic narcotic use (3.91 ± 0.81) were deemed the strongest predictors of poor postoperative outcome, while diabetes (2.71 ± 0.81) and obesity (2.69 ± 0.88) were designated as the weakest predictors. Overall, smoking (3.13 ± 0.91) was the greatest source of discrepancy among responding surgeons. When respondents were stratified according to demographics, there was striking disagreement between specialties. Orthopaedic surgeons and neurological surgeons demonstrated significant discordance with regard to the role of smoking (p < 0.05), narcotic use (p < 0.05), and psychosocial complication (p < 0.05) as predictors of postoperative outcome. Conclusions: Orthopaedic surgeons and neurological surgeons differ in their opinions regarding the role of comorbidities as predictors of outcome following cervical spine surgery. Further studies are needed to investigate the educational and institutional factors underlying this discordance, as well as to determine whether the comorbidities with the highest Likert ratings are indeed the strongest predictors of poor postoperative outcome.

P120 - Revision Surgery After T1 Versus T2 As Lowest Instrumented Vertebra In Multilevel Posterior Cervicothoracic Fusion

Rafael De la Garza Ramos¹, Jonathan Nakhla¹, Jonathan Gomez¹, Merrit Kinon¹, Reza Yassari¹

¹Department of Neurosurgery, Montefiore Medical Center, New York - United States

Introduction: Posterior cervical fusion surgery is a common operative technique for the treatment of patients with myeloradiculopathy or regional deformity. The purpose of this study is to identify the rate of revision surgery after selecting T1 versus T2 as lowest instrumented vertebra (LIV) in multisegmental posterior cervicothoracic fusion procedures. Methods: A retrospective review of our local institutional neurosurgical spine operative database from 2010 to 2016 was conducted. Adult patients (>18 years of age) who underwent multilevel cervicothoracic fusion procedures (≥ 4 or more levels) with either T1 or T2 as LIV were identified. Only patients with at least 12-month follow up were included. Outcome measures included need for revision surgery and postoperative cervical alignment (C2-C7 sagittal vertical axis (C2-C7 SVA), C2-C7 lordosis, and T1 slope). Predictors of revision surgery were identified via logistic regression analysis. Results: There were 37 patients who were identified from our database (9 in the T1 group (24.3%) and 28 in the T2 group (75.7%) with at least 12 months of follow-up (mean: 31.2, range: 12 – 80 months). The rate of revision surgery was 22.2% in patients with T1 as LIV and 17.9% in patients with T2 as LIV (p = 1.00, Fisher exact test). Indications for revision surgery included one case of caudal instrumentation failure, one case of adjacent segment disease, three cases of wound infection, and two cases of screw misplacement. The postoperative C2-C7 SVA (41.9 ± 11.5 vs 38.6 ± 11.2, p = 0.524), C2-C7 lordosis (-5.0 ± 11.6 vs. 6.3 ± 14.7, p = 0.058), and T1 slope (29.0 ± 6.8 vs. 33.3 ± 11.2, p = 0.247) was similar between the T1 and T2 groups, respectively. No preoperative or operative parameters were found to be significantly associated with revision surgery after logistic regression analysis. Conclusion: Patients who underwent multisegmental cervicothoracic fusion procedures down to T1 or T2 showed similar revision surgery rates in this study. Selecting the first versus second thoracic vertebra as lowest instrumented level may not impact the risk of reoperation.

P121 - Transarticular Facet Screw Fixation Of The Subaxial Cervical Spine

Natarajan Muthukumar¹

¹Department of Neurosurgery, Devadoss Multispeciality Hospital, Madurai - India

Aim: To present this author’s personal experience with transarticular facet screw fixation (TAFSF) of the subaxial cervical spine for posterior instrumented stabilization. Methods: Patients with degenerative cervical myelopathy due to cervical spondylosis and/ or OPLL with obliteration of cervical lordosis, reducible kyphosis and/ or subluxation were included in the study. Preoperatively and postoperatively, patients were evaluated using Nurick’s grading, modified JOA score, plain radiographs, CT & MRI of cervical spine. TAFSF was done at the affected levels. Complications were recorded. Follow up ranged from 2 months to 2 years. Results: Period of study: 2012- 2015. Number of patients treated - 14. Twelve underwent TAFSF at the affected levels along with posterior decompression in the form of either laminectomy (10) or laminoplasty (2), two underwent TAFSF alone without decompression following anterior decompression & stabilization. Initially, Takayasu as well as DalCanto’s techniques were used. However, this author’s modified approach described in 2013 was used for the later 8 cases. Takayasu and Dalcanto’s techniques were associated with higher incidence of fracture of the facets. This author’s technique was associated with least incidence of facet fractures and the screw length was longer by 2mms. All the three techniques were able to achieve purchase of four cortices. There were no vascular or nerve root injuries or screw breakages during the follow up. Overall, the cost of TAFSF was 75% less than the cost of conventional lateral mass screw fixation. The limitations include difficulty in performing this technique in patients with short neck and prominent occiput. The advantages include cost reduction, the ability to combine posterior instrumentation with laminoplasty and lower implant profile. Conclusions: TAFSF is a biomechanically stronger, cost-effective and simpler way of posterior instrumentation of the subaxial cervical spine. This technique should be in the armamentarium of every spine surgeon.

P122 - Rare Complications In Cervical Spine Surgery: A National Analysis Of 370 410 Elective Cases

Jonathan Nakhla¹, Rafael De la Garza Ramos¹, Yaroslav Gelfand¹, Andrew Kobets¹, David Altschul¹, Merrit Kinon¹, Reza Yassari¹

¹Department of Neurosurgery, Montefiore Medical Center, New York - United States

Introduction: There is limited data on the occurrence of rare complications after cervical spine surgery, particularly on a national level. The purpose of this investigation is to examine the rate of rare complications after cervical spine procedures in the United States using a large inpatient database. Materials and Methods: The National Inpatient Sample from 2012 to 2014 was reviewed. Data from adult patients who underwent elective cervical spine fusion procedures (anterior, posterior, or circumferential) for degenerative disease or disc herniation were extracted. Sixteen unique rare complications were examined: reintubation, epidural hematoma, incidental durotomy, recurrent/superior laryngeal nerve palsy, pseudomeningocele, Horner’s syndrome, brachial plexopathy, intraspinal abscess, hypoglossal nerve palsy, esophageal perforation, vertebral artery injury, carotid artery injury, thoracic duct injury, blindness (ischemic optic neuropathy), tetraplegia, and inpatient death. Results: The overall rate of rare complications was 1.6% (95% CI, 1.5% – 1.7%); however, each individual complication had an occurrence of 0.51% or less. The three most common were reintubation (0.51%), incidental durotomy (0.51%), and epidural hematoma (0.43%). The rarest complications included blindness (0.003%), carotid artery injury (0.003%), thoracic duct injury (0.0%), and tetraplegia (0.0%). When stratified by operative approach, there was a significant difference in complication rates between anterior (1.4%), posterior (2.3%), and combined (7.5%) approaches (p < 0.001). Compared to patients without complications, patients who developed a rare complication were older (59.6 vs. 55.6 years), more likely to be male (54.8% vs. 48.0%), and have hypertension (59.9% vs. 47.9%), diabetes without complication (21.0% vs. 16.6%), diabetes with complication (4.6% vs. 1.4%), chronic lung disease (24.6% vs. 17.2%), congestive heart failure (1.8% vs. 1.1%), as comorbidities (all p < 0.001). Likewise, they were more likely to undergo circumferential procedures (12.2% vs 2.5%, p < 0.001), corpectomy (14.4% vs. 7.3%, p < 0.001) and revision procedures (7.8% vs. 3.3%, p < 0.001). Conclusion: Major complications after cervical spine surgery are uncommon. Results from this national analysis suggest that fusion procedures in the cervical spine carry a low risk of severe adverse events. Operative approach may significantly impact the risk of rare complications, but future research is encouraged.

P123 - Comparison Of Titanium And N-Ha/Pa66 Cages After Anterior Cervical Fusion With Single-Level Corpectomy Over 8-Year Follow-Up

Bowen Hu¹, Yueming Song¹, Xi Yang¹

¹Department of Orthopedics Surgery, West China Hospital, Sichuan University, Chengdu - China

Introduction: There has been no long term comparison of the efficacy between these two anterior reconstructing cages. This study compares the clinical oucomes of nanohydroxyapatite/polyamide66 cages (n-HA/PA66 cages) with titanium mesh cages (TMC) for application in Anterior cervical discectomy and fusion (ACCF) . Material and Methods: This is a prospective non-randomised comparative study enrolled 41 patients with cervical degenerative diseases who underwent single-level ACCF using TMC or n-HA/PA66 cage from 2008 January to 2009 June. Their radiographic (cage subsidence, fusion status, cervical lordosis, segmental sagittal alignment [SSA]) and clinical (VAS, NDI and JOA scales, postoperative complication) parameters before surgery and at each follow-up was recorded completely. Results: The fusion rate of n-HA/PA66 group was higher than that of TMC both at one year after surgery (94% vs. 84%) and the final follow-up. Cage subsidence rates were 34.5% and 5.4% in the titanium and n-HA/PA66 cages groups, respectively. No significant difference existed between the 2 groups when comparing the mean lumbar lordosis, mean disc height. Lastly, SSA, VAS and JOA in TMC group were worse than in the n-HA/PA66 group (P = 0.235, 0.034 and 0.007, respectively). Two patients presented with cage dislocation without clinical symptoms in the titanium group.The high fusion and low subsidence rates with long time follow-up revealed that n-HA/PA66 cages could be an alternative ideal choice better than titanium mesh cages for ACCF. Conclusion: The n-HA/PA66 cage showed earlier radiographic fusion, less subsidence, larger cervical lordosis and better clinical results than TMC within 8-year follow-up after one-level ACCF.

P124 - Progression Of OPLL After Cervical Laminoplasty

Yoshiharu Kawaguchi¹, Masato Nakano¹, Taketoshi Yasuda¹, Shoji Seki¹, Kayo Suzuki¹, Yasuhito Yahara¹, Hiroto Makino¹, Kenji Kobayashi¹, Tomoatsu Kimura¹

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

Introduction: Cervical laminoplasty is mainly indicated for the treatment of myelopathy caused by ossification of the posterior longitudinal ligament (OPLL). Long term surgical outcome is favourable after cervical laminoplasty in most of the cases. However, as OPLL is a progressive disease, neurological deterioration is not rarely encountered due to the progression of OPLL. In such patients, second surgery has been indicated in our hospital. The purpose of this study was 2 fold: 1) to analyse the incidence of patients who required an additional second surgery due to the neurological deterioration by the progression of OPLL in our single institute, and 2) to clarify the characteristics and surgical outcome of the patients who had second surgery. Material and Methods: Study 1: A total of 162 patients with OPLL, followed up more than 2 years after cervical laminoplasty, were included in this study. The neurological status was graded using the Japanese Orthopaedic Association Score (JOA Score) during follow-up period. We analysed the incidence of the patients who had neurological deterioration due to the progression of OPLL. Study 2: Nine patients who had neurological deterioration due to the progression of OPLL after cervical laminoplasty were included. The clinical background and surgical outcomes were evaluated. We also checked the type of OPLL and the level where the progression occur in these patients. Results: Study 1: The JOA score improved rapidly within a year and continued to improve until 5 years after surgery. It slightly deteriorated at more than ten years follow-up after cervical laminoplasty. Nine out of 162 patients (5.6%) with greater than 3 year follow-up required second surgery due to progression of OPLL. Study 2: The symptoms, such as deterioration of cervical myelopathy, followed by pain or numbness in the unilateral upper extremity, were the most likely symptoms that necessitated second surgery. The incidence of mixed type of OPLL (6 out of 9 patients) was higher in patients requiring the second surgery. Seven patients who had OPLL progression at the level of cervical laminoplasty were treated by anterior decompression and fusion. Posterior decompression was indicated in 2 patients who had OPLL progression at cranial or caudal side. The mean duration from cervical laminoplasty to the second surgery was 11.5 years (1-30 years). Improvement of JOA score was found in 5 patients after the second surgery. However, 4 patients who had MRI-T2 high intensity in the spinal cord did not recover well. Conclusion: 5.6% of the patients required second surgery due to progression of OPLL. The mean duration until the second surgery was more than 10 years, thus long term follow up was necessary after cervical laminoplasty in patients with OPLL. Surgical outcome was not always favourable, therefore early detection of neurological deterioration and suitable surgical treatment might be recommended.

P125 - Assessing Surgical Outcomes For Cervical Radiculopathy And Myelopathy: Comparing Ndi And Promis Pf Cat

Nicholas Spina¹, William Ryan Spiker¹, Brandon D. Lawrence¹, Yue Zhang², Darrel S. Brodke¹

¹Department of Orthopaedics, University of Utah, Salt Lake City - United States ²Division of Epidemiology, University of Utah, Salt Lake City - United States

Introduction: Patient reported outcomes (PROs) are critical in assessing the efficacy of surgical interventions. Recently, the Patient-Reported Outcomes Measurement Information System (PROMIS®) was developed which focuses on many domains of health, one of which is physical function (PROMIS PF). PROMIS PF is not disease specific like many legacy scores including the Neck Disability Index (NDI). It has been shown to have overall good coverage and reliability in patients with musculoskeletal complaints including those with spine pathology. (1, 2) Yet, the responsiveness of PROMIS PF to treatment of cervical spinal pathology has not been investigated. Therefore, the purpose of this study is to evaluate the responsiveness of PROMIS PF and NDI in patients undergoing anterior cervical discectomy and fusions (ACDF) for either myelopathy or radiculopathy. Materials and Methods: A retrospective, single center review was performed identifying patients undergoing a single or two level ACDF for myelopathy or radiculopathy between 2013-present with NDI and PROMIS PF for review. Patients with an additional diagnosis of trauma, tumor, or infection were excluded. PROs were recorded preoperatively and at 6 weeks, 3, 6, and 12 months post-operatively. A Linear Mixed Effect model was used to estimate and compare the adjusted means of both the NDI and PROMIS PF scores at time points between patients treated for myelopathy (MG) vs radiculopathy (RG). Age, gender and BMI were adjusted for in the outcome models. Likelihood ratio tests were employed to examine global differences in the trajectory of patient-reported outcomes. Statistical significance was set at a level of 0.05. Results: 171 patients were identified meeting inclusion criteria, 105 with myelopathy and 66 with radiculopathy. The average PROMIS PF score was significantly higher pre-operatively in the RG compared to the MG (39.6 vs 37.3 p = .006) as well as 1 year postoperatively (42.1 vs 38.1 p = .009). No statistical difference in NDI score was observed between groups at any time point. Both groups demonstrated a positive treatment response over the 12 month period. The mean treatment effect for RG, MG at 6 months was -21.3, -14.3 and at 12 months -15.4, -11.4 in NDI and 2.4, 4.3 at 6 and 2.5, 0.8 at 12 months for PROMIS PF. No significant difference was seen in treatment effect between groups in NDI and PROMIS PF at any time point. Conclusion: Myelopathy and radiculopathy have vastly different presentations. Yet, in our study, these patients were indistinguishable in terms of NDI. PROMIS PF was significantly higher in the RG, both pre- and post-operatively, which is more consistent with a radicular vs myelopathic disease state. The 1 year mean treatment effect, in terms of NDI, surpassed an NDI minimally clinical important difference (MCID) of 7.5. (3) The average treatment effect at 12 months in PROMIS PF was 0.8 MG and 2.5 RG. It is unclear as to the significance of these figures given a PROMIS PF MCID has not been reported. Further study is needed to determine whether PROMIS PF is responsive enough to detect meaningful changes in radicular symptoms given it is largely a test of overall functional mobility.

References

1. Man Hung, PhD; Christine Cheng, BS; Shirley D. Hon, BS; Jeremy D. Franklin, MA; Brandon D. Lawrence, MD; Ashley Neese, BS; Chase B. Grover, BS; Darrel S. Brodke, MD. (2014). “Challenging the norm: further psychometric investigation of the neck disability index.” Spine J.

2. Man Hung, PhD; Daniel O. Clegg, MD; Tom Greene, PhD; Charles L. Saltzman, MD. (2011). “Evaluation of the PROMIS physical function item bank in orthopaedic patients.” J Orthop Res 29(6): 947-953.

3. Carreon LY, Glassman SD, Campbell MJ, Anderson PA. “Neck Disability Index, short form-36 physical component summary, and pain scales for neck and arm pain: the minimum clinically important difference and substantial clinical benefit after cervical spine fusion.” Spine J. 2010 Jun; 10(6):469-74.

P126 - Locking Stand - Alone Cages Constructs For The Treatment Of Cervical Degenerative Disc Disease

Jaime Jesus Martinez - Anda¹, Roberto Alfonso De Leo Vargas¹, Ildefonso Muñoz - Romero¹

¹Neurological Center, ABC Medical Center, Mexico City - Mexico

Introduction: The aim of anterior cervical discectomy and fusion (ACDF) for cervical spine disease is to improve patient symptoms, spine stability and restore lordosis. Locking stand – alone cages (LSC) were developed with the aim of minimizing soft tissue disruption anterior to the vertebrae and reducing the profile of the construct by avoiding an anterior plate, conserving ACDF benefits. Materials and Methods: The study represents a case series of patients surgically treated between July 2015 and July 2017 who received single or multilevel ACDF at the Neurological Center of ABC Hospital, Mexico City, Mexico, by a single surgeon (RdL) with zero – profile X – spine® cervical devices. Inclusion criteria were: (1) signs and symptoms of cervical radiculopathy or spondylotic myelopathy (2) cervical spondylosis confirmed by magnetic resonance imaging (MRI). Exclusion criteria were: (1) ossification of the posterior longitudinal ligament, (2) developmental stenosis, (3) invasive malignancy, (4) evidence of systemic or local infection. Surgical and clinical pre – operative evaluation and surgical outcomes were evaluated using pre and postoperative Nurick, visual analogue scale (VAS), neck disability index (NDI) and japanese orthopedic association score for myelopathy (JOA) scales, cervical Cobb angles, postoperative surgical complications, fusion and subsidence rates. Statistical analysis was processed with SPSS 19.0 for descriptive statistics; and Fisher Xi², Kruskall – Wallis proofs and t – test for dependent samples for univariate analysis. Results: forty-five patients were operated, mean age of 58yo, female / male ratio of 1.8:1; preoperative VAS, NDI and JAO were 8, 31.7 and 15 respectively. Preoperative Cobb's angle was 33.7º. Forty – four percent of patients had 1 level, 40% two level, and 16% three level disease. Cervical axial or radicular pain was present in all patients. Thirty – three percent of patients had Nurick 0 medullar disease, 48.9% grade 1 and 15.6% grade 2. Cervical level most affected was C5 – C6 in 77.7% of patients, as a single level (28.9%) or as a part of a multilevel disease. On preoperative MRI, foraminal stenosis was present in 93.3%, medullar stenosis in 51.1% and medullar hyperintensity on T2 sequence in 28.9%. Complications rate was 6.7%, 2 patients having postoperative dysphagia (4.4%), and 1 patient having a surgical site hematoma. Mean postoperative follow – up time was 6 months; postoperative VAS, NDI and JAO were 2.4, 15.9 and 15.7 respectively (improvement, p ≤ 0.001). Postoperative Cobb's angle was 40.2º (improvement, p ≤ 0.001). Fusion rate was 84.4%, and subsidence rate was 11.1%. No statistical difference was found at clinical or radiological outcome between patients with 1 or > 1 cervical level disease. Conclusions: Stand – alone ACDF with zero – profile cervical devices is an excellent option for cervical degenerative disc disease of one, two and three levels, with similar results reported with ACDF with cages and plate.

P127 - Combinatorial Surgical And Neuroprotective Therapy For Cervical Spondylotic Myelopathy Results In Improved Neurological Function: From Preclinical Proof Of Concept To A Phase Iii Randomized Controlled Trial

Michael Fehlings¹, Spyridon Karadimas¹, Branko Kopjar², Paul Arnold³

¹Department of Surgery, University of Toronto, Toronto - Canada ²Department of Health Services, University of Washington, Seattle - United States ³Department of Neurosurgery, University of Kansas Medical Center, Kansas City - United States

Introduction: Surgical decompression is an effective treatment for cervical spondylotic myelopathy (CSM). However, a number of patients continue to experience substantial neurological impairment post surgery. Riluzole has neuroprotective effects in injuries of the central nervous system. To determine the efficacy of riluzole for promoting neurological improvement in CSM following decompression, we performed a pre-clinical proof of concept experiment and then we translated our work and established a Phase III multi-center randomized controlled clinical trial (CSM-Protect). Material and Methods: Surgical decompression was performed in a rat CSM model and riluzole, or control, was administered. Spinal cord blood flow (SCBF) was evaluated in all CSM rats, in vivo, before and after decompression using FAIR MRI. The long-term outcomes of decompression with or without riluzole treatment determined using neurobehavioural and neuroanatomical assessments. Our multi-center double-blind randomized CSM-Protect trial includes a total of 300 CSM patients undergoing decompression surgery and randomized 1:1 to receive riluzole (2x50 mg daily for 14 days before and 28 days post surgery) or placebo treatment. MJOA score will determine the effectiveness of the combinatorial treatment at 6 months following surgery. Statistical analysis will be performed as a sequential adaptive trial with interim analysis. Results: Rats receiving combinatorial treatment displayed long-term significant neurological improvements associated with preservation of motor neurons and corticospinal tracts compared to rats treated with decompression alone. Riluzole also dramatically reduced the extent of ischemia-reperfusion injury post surgical decompression in our animal model. At present, 299 subjects have been enrolled into the CSM-Protect trial. A planned interim analysis using this sample has commenced. Conclusion: The proposed combinatorial therapy promotes neurological recovery in CSM rats. Confirmation of this proof of concept has been translated from bench to the bedside and we are currently running the CSM-Protect trial to determine the efficacy of this combinatorial treatment option for use in CSM patients.

P128 - The Natural History Of Patients With Cervical Radiculopathy Treated Conservatively -- Clinical And Mri Features After A Mean Follow-Up Of 3 Years

Aditya Banta¹, Saumyajit Basu¹, Amitava Biswas¹, Sandeep Kesharwani¹, Anil Solanki¹

¹Neurosciences Division, Park Clinic, Kolkata - India

Introduction: The clinical response of cervical disc herniation presenting with radiculopathy, treated conservatively is known to be favorable. However few published studies are there regarding the radiological outcome. The present study attempts to evaluate the clinical and radiological natural history of such patients. Materials and Methods: 30 patients of acute cervical radiculopathy presenting to our institution from Jan 2012 to April 2015 with corresponding single level disc herniation on MRI were included in the study. Mean follow up period was 37 months (range 18 to 58). Functional assessment tools used were Neck Disability Index (NDI) and Visual analogue scale (VAS) of neck and arm pain. The index and follow-up MRI were graded for disc degeneration (Miyazaki Score), neuroforaminal stenosis (NFS) (Kim’s Score) by 3 independent observers, Calculation of protruded disc volume was done too. Patients with myelopathy were strictly excluded. All patients were managed with Analgesics and Pregabalin along with Physical therapy (TENS). Results: 30 patients with mean age of 45.26 years (range 31-68), with mean initial VAS score of neck/arm of 6/8, improved to 2/1.3 respectively (p < 0.001). NDI score improved from 53.73 (range 22.2 - 90) to 20.19 (range 0-42.2) (p < 0.001). Inter observer reliability for NFS scoring was good (k = 0.60 - 0.66) whereas it was poor for Miyazaki score (k = 0.20-0.35). NFS grade for involved side decreased from average of 1.52 to 1.08 (p < 0.05). Average protruded disc volume changed from 222 to 125 mm3 (p < 0.05) We did not find any correlation between improvement of NDI scores and improvement of NFS or protruded disc volume. Conclusion: Clinical improvement is a rule in cervical radiculopathy patients. MRI showed statistically significant regression of NFS on follow up. Correlation between the two was not found. Observation regarding disc degeneration was inconclusive with poor inter-observer reliability.

P129 - Clinical Adjacent-Segment Pathology After Anterior Cervical Discectomyand Fusion: Results After A Minimum Of 10-Year Follow-Up

Sung Kyu Kim¹, So Hyun Moon²

¹Department of Orthopedic Surgery, Chonnam National University Hospital, Gwangju - Korea, Republic ²Department of Nursing, Chosun University, Gwangju - Korea, Republic

Introduction: To evaluate the incidence, predisposing factors, and impact of radiographic and clinical adjacent-segment pathologies after anterior cervical discectomy and fusion using cervical plates and to analyze the efficacy of this surgical method over the long term, after a minimum follow-up period of 10 years. Material and Methods: Our study was a retrospective analysis of 177 patients who underwent anterior cervical discectomy and fusion using cervical plates, with follow-up periods of at least 10 years (mean 16.2 years). We defined a new grading system of plain radiographic evidence of degenerative changes in adjacent discs after anterior cervical discectomy and fusion using cervical plates; Grade 0 is considered normal, and Grade V consists the presence of posterior osteophytes and a decrease in disc height to less than 50% of normal. The incidence, predisposing factors, and impact of radiographic and clinical adjacent-segment pathologies were analyzed according to etiologies, number of fused segments, and plate-to-disc distance. Results: Radiographic and clinical adjacent-segment pathologies were found in 92.1% and 19.2%, respectively, of patients. By etiology, clinical adjacent-segment pathology was observed in 13.5% of patients who had sustained trauma, 12.7% of those with disc herniation, and 33.3% of those with spondylosis. By number of fused segments, clinical adjacent-segment pathology was found in 13.2% of patients who underwent single-level fusion and in 32.1% of those who underwent multilevel fusion surgeries. Patients with a plate-to-disc distance of less than 5 mm, who had spondylosis, or who underwent multilevel fusion had a higher incidence of clinical adjacent-segment pathology after anterior cervical discectomy and fusion using cervical plates than other groups did. Of all patients, only 6.8% needed follow-up surgery. Conclusion: We found that over the long term, at a minimum follow-up point of 10 years, a plate-to-disc distance of less than 5 mm, having spondylosis, and undergoing multilevel fusion were predisposing factors for the occurrence of clinical adjacent-segment pathology. Nevertheless, the incidence of clinical findings of adjacent-segment pathology was much lower than the incidence of radiographic findings. Also, the rate of follow-up surgery was low. Therefore, anterior cervical discectomy and fusion using cervical plates can be considered a safe and effective procedure.

P130 - Influence Of The Parameters Of The Local Sagittal Balance Of The Cervical Spine On The Quality Of Life Of Patients Operated On For Degenerative Disease

Vladimir Klimov¹, Vladislav Kelmakov¹, Aleksey Evsukov¹, Evgeniy Loparev¹, Roman Khalepa¹, Vidzhay Dzhafarov¹

¹The Federal Neurosurgical Center of the Russian Ministry of Public Health, Novosibirsk - Russian Federation

Introduction: to study the effect of the parameters of the local sagittal balance of the cervical spine on the quality of life of patients operated on for degenerative-dystrophic disease. Material and Methods: From 2014 till 2017 56 patients with lumbar spine scoliosis were operated in the Federal Neurosurgical Center (50 men and 50 women). The patients’ age was 49,8 ± 9,8 years. The mean follow-up period was 23.6 ± 12.4 months. Patients’ neurological status evaluation was performed according to Japanese Orthopedic Association 1994 (JOA). The severity of the pain syndrome was assessed by a visual analogue pain scale (VAS). To assess the quality of life, the Neck Disability Index (NDI) questionnaire was used (H. Veron, J. Mior, 1989) according to the scale of The Short Form-36 (SF36). Neuroimaging methods included MRI, MSCT and X-ray. According to the radiographs, the assessment of the Sagittal vertical axis (SVA) C2-C7, the SVA center gravity of the head (CGH) -C7, the Cobb angle C2-C7, the Spino-cranial angle (SCA), the Thoracic inlet angle (TIA) neck tilt NT), T1 slope, C7 slope, Cranial incidence (CI), Cranial slope (CS), Cranial tilt (CT). Results: During the follow-up period, a positive correlation was found between C7 Slope and NDI (r = 0.31, p = 0.02). Perhaps a negative relationship between C7 Slope and SF36-PH (r = -0.27, p = 0.06). Positive correlation (on the verge of significance) between SVA C2-C7 and NDI (r = 0.24, p = 0.08). The value of the NDI questionnaire (p = 0.03) is worse in the group of patients with SVA C2-C7 more than 40 mm. In the group with “front” surgery, more than 75% of patients have SVA CGH-C7 less than 40 mm, in the “back” - more than 40 mm in all patients (p = 0.01). The balance after surgery is compensated in the most patients in the group of ventral surgery. Meanwhile, SVA CGH-C7 and clinical studies have not been detected, although SVA CGH-C7 and C2-7 strongly correlate (SVA CGH-C7 and SVA C2-7 (p = 0.000)). Conclusion: The parameters of C7 slope, SVA C2-C7 of the local sagittal balance statistically significantly affect the patient’s quality of life (according to NDI, SF-36). A statistically significant threshold for SVA C2-C7 for decompensating the sagittal balance was 40 mm. In patients after ventral surgery SVA CGH-C7 is reliably below 40 mm, however, no statistically significant correlation was found with clinical outcomes.

P131 - Hybrid Constructs Versus Acdf In The Surgical Treatment Of Multisegmental Degenerative Cervical Disc Disease

Balazs Szollosi¹, Laszlo Kiss¹, Aron Lazary¹, Peter Pal Varga¹

¹National Center for Spinal Disorders, Budapest - Hungary

Introduction: In most of the patients with multisegmental cervical degenerative disc disease certain segments can show different stages of degeneration and instability. This condition may require an individual surgical strategy and the use of hybrid construction with combination of fusion and arthroplasty. Our study was designed to evaluate the clinical and radiological outcome and the possible differences between ACDF procedure and hybrid. Material and Methods: Patients with symptomatic cervical radiculopathy and/or myelopathy, who underwent cervical spinal surgery in between 2010 and 2015 were enroled into the study. Hybrid construct group contained 36 patients with 2- to 4-level surgeries. The control group (n = 15) included patiens with 2- to 4-level ACDF surgery. The aim of study was to compare the clinical and radiological mid term (min. 2-year follow up) results of hybrid versus ACDF group. Patient related outcome measures were used to determine the outcome of the surgery. VAS for pain, Neck Disability Index, sensomotory function and the radiographic parameters (cervical lordosis, range of motion of the) were evaluated during the study period. Results: Improvement in pain was significant in both groups (hybrid: dVAS = 5.0, p < 0.05, ACDF: dVAS = 3.0, p < 0.05), however in the control group the decrease in pain was less at the last follow-up (p < 0.05). The mean cervical lordosis was improved from 1.7° to 16.2° (p < 0.05) in the hybrid group. In the control group the change of the lordosis was not significant (from 7.8° to 11.2°, p>0.05). Conclusion: Based on our results good clinical outcome could be achieved with both surgical method. The main theoretical advantage of the hybrid surgery is to reduce the lenght of rigid spinal segments, that decrease the mechanical stress in the adjacent segment. In our cohort, the mid-term clinical and radiological outcome of the multilevel cervical hybrid surgeries are look promising. However, long-term follow up studies are required with bigger kohort to prove the role of hybrid constructs in surgical treatment of multisegmental cervical degenerative cases.

P132 - Neurological Recovery Pattern In Cervical Spondylotic Myelopathy After Anterior Decompression And Plating - A Prospective Study With 1 Years Follow Up

Naveen Pandita¹, Prince Raina¹

¹Department of Orthopaedics, AIIMS Rishikesh - India

Introduction: Surgical decompression of the cervical spondylotic myelopathy is preffered method of treatment and has shown good to excellent functional outcome. Neurological recovery and regression of myelopathy symptoms is one of the important factors determining final out come after surgical decompression. This study adds to the present literature regarding the pattern of neurological recovery and prognosticating the patient about the resolution of their myelopathy symptoms after surgery. Material and Methods: This prospective study was conducted in the Postgraduate Department of Orthopedics, Government Medical College and Associated Hospitals, Jammu from November 2012 to October 2014.A total of 30 consecutive patients of cervical spondylotic myelopathy were treated by anterior decompression and stabilization were prospectively followed for 1 Year and evaluated for short term results of-Overall neurological outcome, Overall Neurological recovery pattern and specific Neurological recovery pattern. Postoperative outcome was evaluated using the mJOA score . Recovery rate was calculated using Hirabayshi’s method. The JOA score was assessed before the operation, at 1 week, 2 weeks, 1 month, 3 months, 4 months, 6 months and 1 year. The pattern of neurological recovery in the overall JOA scores, upper limb function JOA score, lower limb function JOA score and sphincter function JOA score after surgical decompression were documented and analysed Results: Postoperative mJOA in the 1st month was 0, in the 3 rd month was 12.90 ± 3.57, in the 4th month was 13.50 ± 3.55, in the 6th month was 14.63 ± 3.62 and in the final followup of 1 year was 14.9 ± 3.24. The average recovery rate during 1st month follow-up was zero percent. The average recovery rate during 3 rd month follow-up was 12.91% with a range of 50 to 0%. The average recovery rate during 4th month was 32.5% with a range of 0 to 60%. The average recovery rate during 6th month was 72.83% with a range of 0 to 100% and the average recovery rate during the final follow up of 1 year was 54.3% Conclusion: Neurological recovery after the surgical decompression starts from the 3 rd post operative month and increase till the 6th postoperative period and then gradually pleatues over the duration of next six months till it becomes static. Upper limb neurological function recovers better than lower limb function which has better recovery rate than bladder function. Duration of symptoms is an important factor to be considered in determination of postoperative neurological recovery.

P133 - Using Cervical Titanium Coated Peek Cages In The Smoking Population Provides Fusion Rates Equal To Non-Smoking Population

Geert Mahieu¹

¹Department of Orthopedic Spine Surgery, Antwerp - Belgium

Introduction: Based on literature data, smocking is associated with an increased rate of pseudarthrosis following anterior cervical discectomy and fusion (ACDF). Peek cages coated with a Titanium layer are meant to increase and accelerate fusion rates in ACDF surgery. In this study we evaluate if cervical PEEK cages with a Fine Grained Osseo Integrative Coating of Titanium (FGOIC-Ti) can increase the fusion rate in smokers to the same rate as in non-smokers. Materials and Methods: 63 patients received a cervical fusion for radiculopathy or myelopathy by one single surgeon. Cages with FGOIC-Ti were used in all patients. The cages were filled with a fully resorbable paste made of magnesium substituted hydroxyapatite nano-crystals. A plate with screws was used in every patient. Patients were evaluated radiographically with flexion extension x rays, three months postoperatively. After 6 months a CT scan was made of every patient. Only when the interspinous distance of the fused level did not change > 2 mm in flexion extension x-rays, the level was considered fused at three months. When there was bone bridging fusion on CT scan, fusion was confirmed. Results: 63 patients (M/F = 33/30) with a mean age of 50 years old (M/F = 53/44) were evaluated. Thirty of these patients were smokers (M/F = 15/15). 96 cages were placed with a smoker/non smoker ratio of 51/45 (53%/47%). In the smoking group, 16 patients were operated at one-, 13 patients at two- and 1 at three levels. In the non-smoking group it was 17 (one level), 14 (two level) and 2 (three level). One patient (3%) in the non-smoking group developed a pseudarthrosis after 6 months. In the smoking group also one patient (3,3%) had no full bony fusion on CT scan after 6 months. We did not see any case of cage subsidence or any other hardware failure. Conclusion: Fusion rates are excellent when FGOIC (Ti) cages are used in the cervical spine. Furthermore they are similar for smokers and non-smokers. No subsidence occurred and assessment is perfectly possible with flexion extension X-rays or CT scan. Further (larger) studies are needed to confirm the potential for titanium coated cages to increase fusion rate in the smoking population to the same level as in the non-smoking population.

P134 - Comparison Of Different Grafts In Anterior Cervical Discectomy And Fusion Surgery

Matjaz Vorsic¹, Tomaz Velnar¹

¹Department of Neurosurgery, University Medical Centre Maribor, Maribor - Slovenia

Introduction: Anterior Cervical discectomy and fusion (ACDF) is a standard treatment for disc herniation and degenerative disc disease in the patients where conservative treatment failed. Different grafts and cages can be used to achieve the solid fusion. The primary aim of our study was to compare clinical results as well as the rate of fusion and bone ingrowth using different implants to achieve the fusion in ACDF. Methods: After applying the inclusion criteria, 100 patients with cervical degenerative disc disease who underwent the ACDF procedure were included in the study treated in either group. Clinical outcomes were assessed before and at regular intervals until two years after the procedure using neurological examination, the Neck Disability Index (NDI) and Visual Analogue Scale (VAS) for neck and arm pain, with 15% improvement in NDI and 20% in VAS defined as a clinically significant. The rate of fusion, fusion speed and bone ingrowth were evaluated using cervical CT scans. Fusion was defined as trabecular continuity across the disc space anterior, through and posterior to the cage proximally and distally. Results: The treatment groups included ACDF with autograft (n = 15), ACDF with PEEK Anterior Cervical Interbody Spacer (ACIS) (n = 43), ACDF with PEEK stand alone Cage (n = 30), ACDF with PEEK ACIS together with bone graft substitute (n = 12). The groups were similar at baseline both clinically and statistically (P >.05) except for age and VAS for arm pain. All groups had a statistically significant improvement in NDI and VAS for neck and arm pain (P <.05) and there was no statistically significant difference between groups at any point of investigation. The fusion rates were 88% for autograft, 95% for ACIS, 97% for stand alone cage and 100% for ACIS with bone graft substitute. The fusion speed was highest with stand alone cages and ACIS with bone graft substitute group. Conclusions: All implants resulted in significant pain reduction and functional outcome for the patients. The fusion rate was much better with artificial cages than with autograft substitutes and was perfect with the implants combined with bone graft substitute. The number of the patients included in this group was however significantly smaller than in the others.

P135 - Comparison Between Zero-Profile Implants And Anterior Cervical Plate And Cage: A Surgeon Experience

Reuban D’Cruz¹, Terry Teo¹, John Chen¹

¹Singapore General Hospital, Singapore - Singapore

Introduction: Anterior Cervical Decompression and Fusion (ACDF) using plate and cage construct remains the gold standard treatment for Cervical Radiculopathy and Myelopathy. The aim of this study is to analyze and compare the prospectively collected data in patients treated with single- or multilevel ACDF, using stand-alone, zero-profile device versus anterior cervical plate and spacer construct. The data focusses on evaluating on clinical outcome and complications with each modality. Materials and Methods: This retrospective case series from 2008 till 2015, includes 55 patients who were treated by Zero-Profile implant & 56 patients by anterior cervical plate and cage for degenerative cervical disc disease by a single surgeon. Patient demographics, operative details and complications were reviewed. The patients were evaluated pre-operatively and post-operatively according to the Neck disability index (NDI), visual analog score (VAS) score, JOA Score and SF36 score. Analyses were based on comparisons in peri-operative functional outcomes and clinical metrics, using paired Student t test. Results: 55 & 56 patients were available for 2 year follow-up from the Zero-P implant and Anterior cervical plating groups respectively. There was no statistical differences in patient demographics, operative details or length of hospital stay between both groups. 2 patients had required subsequent surgeries for adjacent segment disease. The results of the remaining patients are as follows: NDI scores improved significantly from preoperative to the 2 year follow-up in both groups (p < 0.01). JOA scores & SF36 scores were noted to have increased at 2-year post-operative follow-up compared to pre-operative measurements (p < 0.05). Mean VAS scores for Neck & Upper Limb pain were recorded to be better in Zero-P implant group compared to the Anterior Cervical plating group (p < 0.05). There was no statistical difference in mean scores from either group, except for VAS scores. Thirteen patients complained of transient dysphagia with no statistical difference in both groups (p = 0.4). Conclusions: Anterior cervical discectomy and fusion with Zero-Profile implants resulted in similar clinical and functional outcomes as compared with anterior cervical plate and spacers.

P136 - Subsidence Of Peek Cage After Anterior Cervical Fusion

Yong Min Kim¹, Ban Suk Go¹

¹Department of Orthopedic Surgery, Chungbuk National University, Cheongju - Korea, Republic

Purpose: The purpose of this study is to evaluate the rate and direction of subsidence that occurred after anterior cervical discectomy and fusion using Polyetheretherketone(PEEK) cage and to analyze the risk factors of subsidence.

Materials & Method: Thirty two patients (36 segments) who underwent anterior cervical discectomy and fusion using PEEK cage and autologous cancellous iliac bone graft from July 2003 to November 2011 were enrolled in this study. Anterior Segmental Height(ASH), Posterior Segmental Height(PSH) and Cage Corner Distance(CCD) were measured on the plain radiographs. Subsidence was defined as ≥ 2 mm decrease of the average of ASH and PSH at the final follow up compared to that measured at the immediate postoperative period. The decrease more than 3 mm was defined as severe subsidence for further statistical analysis. Result: Subsidence more than 2 mm was observed in 14 segments (38.9%) and severe subsidence (≥ 3 mm) was observed in 7 segments (19.4%). The direction of subsidence was examined by the comparison of means of decreased ASH & PSH and anterior subsidence outweighed posterior subsidence (p < 0.001). Examination of CCD revealed that inferior subsidence was more frequent than superior subsidence (p < 0.001, p = 0.047). Among the suspicious risk factors for subsidence, intraoperative disc space distraction (anterior distraction: p = 0.031, posterior distraction: p = 0.007) and height of inserted cage (p = 0.032) were statistically significant. Conclusion: There are considerable incidence of subsidence after cage. Using a cage of appropriate height and preventing intraoperative over-distraction of disc space will be helpful to prevent subsidence of cage after anterior cervical discectomy and fusion using PEEK cage.

Keywords: subsidence, anterior cervical discetomy and fusion, Polyetheretherketone(PEEK) cage, segmental height, cage corner distance.

P137 - Management Of Cervical Spondylotic Myelopathy With Total Cervical Disc Arthroplasty: A Analysis Of 18 Patients With Clinical And Radiographic Diagnosis Of Cervical Myelopathy

Christoph Mehren¹, Tuna Pehlivanoglu², Franziska Heider¹, Daniel Sauer¹, Andreas Korge¹, Christoph Siepe¹, Michael Mayer¹

¹Spine Center Schön Klinik München Harlaching, Munich - Germany ²Istanbul University, Istanbul Faculty of Medicine, Department of Orthopaedic Surgery and Traumatology, Istanbul - Turkey

Introduction: Over the past decade, total cervical disc replacement (cTDR) has been established as a viable treatment option for cervical degenerative disc disease. Especially patients with radiculopathy due to certain disc pathologies have been treated successfully with excellent clinical long-term results in the past. The aim of this study is to question the clinical and radiographic efficacy of Pro Disc Vivo cervical disc arthroplasty in patients with clinically and radiographically documented myelopathy, due to degenerative changes at the index level. Patients and Methods: 18 consecutive patients (10 males, 8 females) with documented clinical and radiological signs of myelopathy, as part of an ongoing prospective non-randomised single center study, were included in this investigation. All of the patients underwent the same procedure through an anterior cervical approach and a ProDisc Vivo cervical disc prosthesis was inserted within strict inclusion criteria (e.g. no instability, no kyphotic deformity, residual motion of the index segment, no distinct bony osteophytes, no osteoporosis). MRIs were taken routinely to confirm the diagnosis of spinal stenosis with myelopathy. Conventional x-rays of the cervical spine were taken in ap and lateral as well as in flexion/extension to determ the global lordosis as well as the range of motion (ROM). Patients without radiographic (MRI) evidence of myelopathy were excluded. Enrolled patients were calculated Nurick grade together with VAS, NDI and JOA scores preoperatively and also during the follow-up appointments. Results: The study population had a mean age of 52.4 years and a follow up period of 20.3 months in average (range 3-48 month). Cervical disc arthroplasty was performed in 15 patients for one, in 2 patients for two and one patient for three levels. The mean range ROM of the index level stayed consistent with 9.4° preoperatively and 9.6° (p = 0637) at the last follow up, the global lordosis in neutral position changed from 5.8° to 14.2° significantly (p = 0.002). The JOA score improved from 11.3 (Grade I: 9 patients, Grade II: 9 patients) to 16.62 (all patients: Grade I) (p < 0.001/p = 0.003) as well as the NDI 36.71 (73.43%) to 10.3 (p < 0.001) and the VAS score from 5.71/6.07 (arm/neck) to 1.3/2.0 (p < 0.001/p < 0.001). The mean Nurick grade was 1.33 preoperatively and droped down in all cases to Nurick grade of 0 (p < 0.001). At the latest follow-up visit all patients were highly satisfied by means of social functioning and pain. They were all able to return to work, daily activities and recreational sports. Conclusion: This study proved that ProDisc Vivo cervical disc arthroplasty was a viable treatment option with excellent outcomes even in management of cervical myelopathy with regard to pain scores (VAS) and neck disability index by improving the neurologic deficit, arm pain and local neck symptoms together with scores of functional outcome (JOA and NDI scores). Considering the Nurick grades our clinical results revealed as well, that anterior decompression and implantation of cTDR could improve the severity of myelopathy within strict inclusion criteria. This study also concluded that cTDR was improving the pre-operative ROM and lordosis with great statistical significance which was a highly remarkable result lacking in the literature.

Degenerative Lumbar

P138 - Need For Subsequent Fusion After High Risk Posterior Lumbar Decompressions

Ryan Hoel¹, Melissa White¹, Sharon Yson¹, Jeffrey Luna², Jonathan Sembrano¹

¹Department of Orthopaedic Surgery, University of Minnesota, Minneapolis - United States ²Department of Orthopaedic Surgery, Minneapolis Veterans Affairs Medical Center, Minneapolis - United States

Introduction: The risk of postoperative instability is thought to be high in patients with several consecutive spinal levels decompressed. Additional decompressions thought to be at high risk for subsequent instability include posterior decompressions adjacent to a fusion, and decompressions for spondylolisthesis. Traditional wisdom dictates that decompressions meeting one of these criteria should be coupled with fusion to prevent instability. We sought to investigate the subsequent fusion and reoperation rates of patients undergoing these “high risk” decompressions. Material and Methods: We retrospectively reviewed the charts of all lumbar spine surgeries performed over a 15-year period at a single Veterans Affairs hospital, and identified those who underwent multilevel (≥3) adjacent decompressions without fusion (M), decompressions adjacent to prior fusions (PF), decompressions adjacent to concomitant fusions (CF), and isolated decompressions for spondylolisthesis (S). Records were reviewed to determine if any subsequent spinal operations were performed. We attempted to contact all patients by phone to inquire if they had received spine surgery outside our institution. If a patient was unable to be contacted, the follow-up time point was recorded as the last clinic visit with our department. Patients with less than 11 months of follow up were excluded. Results: Seventy-seven patients met inclusion criteria. Of these patients, 56 were in group M, 9 were in group PF, 20 were in CF, and seven were in S. Median follow up time was 34 months (range 11-143). Of the 77 patients, nine (12%) went on to subsequent arthrodesis. Of the arthrodeses, three were in group M (5% group total), two were in group PF (22% group total), two were in group CF (10% group total), and two were in group S (29% group total). Conclusion: Our results show a low incidence of subsequent fusion after these “high risk” decompressions. The group undergoing three or more consecutive decompressions without fusion (group M) had the lowest rate of subsequent arthrodesis compared to the PF, CF, and S groups. These results suggest that the need for subsequent arthrodesis in decompressions of three or more consecutive levels without concomitant fusion may be less than dictated by conventional wisdom and broad clinical practice.

P139 - Correlation Between Lumbar Epidural Fat And Subcutaneous Or Visceral Fat

Keigo Yasui¹

¹Department of Orthopedic Surgery, Obihiro Kosei Hospital, Obihiro - Japan

Introduction: Despite the lumbar epidural fat exists physiologically, it sometimes compresses thecal sac and causes spinal epidural lipomatosis when it proliferates. Although obesity and steroid-use are the risk factors of the proliferation, there are few knowledge concerning the correlation between the extent of epidural fat and subcutaneous/visceral fat. The purpose of this study was to investigate the correlation between them and some other individual parameters. Material and Methods: Both lumbar MRI and abdominal CT which had taken within one year prior or later to the MRI, from the image database in author’s institution from March 2014 to August 2016 were extracted. The cases with history of lumbar and/or abdominal surgery or those with inappropriate images to measure were excluded. The epidural fat (EF) was measured two dimensionally by T1 weighted mid-sagittal MRI. Maximum high intensity areas ventral and dorsal to the thecal sac at each L1/2 to L5/S1 level were aggregated. The circumferences of the abdomen (CA), the square measures of subcutaneous fat (SF) and visceral fat (VF) at the umbilical level on abdominal CT were automatically measured by the image analysis software (Vincent, Fujifilm Corp., Japan). As the individual parameters, gender, weight, body mass index (BMI) and comorbidities such as diabetes, steroid-use or metabolic syndrome were recorded. The correlations between the extent of EF and other parameters were investigated. Pearson’s correlation coefficient and unpaired T-test were engaged for statistical analyses and significance was set at p < 0.05 for all comparisons. Results: A total of 63 cases (31 males and 32 females, 69.3 years in average) were evaluated. EF amount was correlated to CA, SF, VF, weight and BMI (r = 0.55, 0.49, 0.43, 0.58, 0.56, respectively). Especially in females, the correlations to SF (r = 0.59) and VF (r = 0.55) were markedly. There was no statistical difference between EF and VF (r = 0.29, p = 0.12) in males. In those with diabetes (n = 18), steroid-use (n = 18) and metabolic syndrome (n = 23), there were no significant correlations to EF amount compared to those without (p = 0.18, 0.23, 0.13, respectively). Conclusion: We investigated the correlation between the extent of lumbar EF and several parameters such as CA, extent of SF or VF, weight and BMI. In this study, statistical differences were not shown in terms of the correlation to the extent of epidural fat with or without diabetes or steroid-use. The extent of lumbar epidural fat was significantly correlated to those parameters especially in females.

P140 - Extreme Lateral Interbody Fusion As Solution For Complex Failed Back Surgery Syndrome A Case Report

Andrea Veroni¹, Aldo Sinigaglia¹, Giovanni Casero¹, Mattia Sedia¹, Antonio Schirinzi¹, Vitaliano Nizzoli¹, Marco Ruini¹

¹Spine Surgery Unit, Salus Hospital, Reggio Emilia, Reggio Emilia - Italy

Introduction: Several articles identify the great potentiality of the Extreme Lateral Interbody Fusion (XLIF) in treatment of pseudoarthrosis, junctional disease and sagittal imbalance due to ipolordosis or segmentary kyphosis. We challenge this technique in a complex case with FBSS and Sagittal imbalance. Material and Methods: A 77 years-old man experienced sudden loss of strength at the left legs, with a L5 left palsy after a posterior microsurgical decompression and L4/5 microdiscectomy for a lumbar stenosis. The MRI showed a huge recurrent L4/5 herniated disc with migration behind the posterior wall of the L5 and an Upright Whole Spine Radiography revealed an important sagittal imbalance. In this case the surgical planning is very complex because of the presence of herniated disc, scar and sagittal imbalance. According to that topics, we approached a surgical operation through a combined procedure with a surgical first-time: a lateral approach (XLIF) in order to remove pathological disc L4/5 and restore lordosis, without getting in trouble with scar tissue. Then, we proceeded with the surgical second-time: posterior approach positioning of pedicular screws in L4, L5 and S1 and a TLIF in L5/S1. The scar was too adherent to dural sac and so we didn’t remove it. Finally, the patient awaked with sudden release of the leg pain, an immediate partial recover of the L5 left palsy and returned at home in day 6, to start physiatrics’ program two month later. Results: This patient presents several critical problems: sagittal imbalance, recurrent herniated disc and epidural and periradicular scar. For these multiple criticality, we decide to solve all the problems with a combined approach through a surgical first-time, proceeding with an XLIF in L4/5, in order to restore intervertebral space and lordosis and remove much degenerate disc material as possible away from the epidural scar. The neuromonitoring ensures safety of the procedure and MIS instrumentation with tubular retractor and fiber-optic light ensure a constant control of the curettage of the degenerate material. Then, immediately after suture of the skin incision we pass to the surgical second-time, consisting a posterior approach with decompression of the spinal canal through removal of facet joint and we try to remove scar tissue, but this is too adherent to dural sac and so we decide to avoid further damage. Finally we fix the screws with the rods applying compression force to give much load as possible on the cage in order to perform an optimal arthrodesis. Conclusion: Our experience in treating this patient suggest that also in case of FBSS and in case of patient underwent several surgical procedure XLIF result in satisfy and safety solution with also the possibility of removal of herniated disc, reducing risk of damage of the neural structure. Also, the good results in this patient demonstrate that is very important for a spinal surgeon to know different kind of technique in order to find the better strategy to solve all the patient’s problems.

P141 - A Long Term Follow Up Study Of Posterolateral Fusion With Posterior Instrumentation In Spondylolisthesis

Jayakumar Subbiah¹, Devadoss Annamalai¹, Sathish Devadoss¹

¹Department of Orthopaedics, Devadoss Multispeciality Hospital, Madurai - India

Introduction: Spondylolisthesis, a heterogenous group of disorder characterised by the forward displacement of one vertebra over another. The essential lesion that permits the forward slippage is an interruption in the continuity of the pars interarticularis especially in the isthmic type of spondylolisthesis, usually characterised by symptoms of back pain, leg pain and nerve root irritation. Conservative treatment is suitable for patients with tolerable pain. Surgical treatment is indicated if the symptoms are disabling and interfere with work, if it is progressive and if there is a significant neurological compression. The study aims to assess the clinical, functional and radiological outcome of decompression, posterolateral fusion with posterior instrumentation in the treatment of lumbar spondylolisthesis. Material and Methods: 83 patients with isthmic and degenerative spondylolisthesis were operated with decompression, posterior instrumentation and posterolateral fusion were evaluated. It was a retrospective and prospective study conducted at Devadoss Multispeciality Hospital, Madurai from the year 1995 to 2017. The criteria for inclusion were all cases of spondylolisthesis (grade 1 to grade 4) with symptoms severe enough to warrant surgery. The patients were evaluated preoperatively with Low back ache disability questionnaire (Oswestry) which was modified for Indian conditions to include 9 assessments for a total score of 45. Clinical evaluation was by assessing back pain, leg pain, presence of neurological deficit and radiological parameters (Grade or amount of slip (Meyerding) the percentage of slip and the sacrohorizontal angle). The indications for surgery were neurological claudication, neurological deficits, severe persistent back pain, high grade slip with instability, back pain not controlled by conservative treatment. The surgery performed was a decompression, posterior instrumentation (Pedicle screws) and intertransverse fusion. Post operatively, patients were gradually mobilised from sitting and then walking with LS belt which was worn for 3 months. Patients were evaluated at 1,3,6,12 months after surgery and were assessed clinically, radiologically. X-rays were taken and were assessed for the amount of listhesis, the percentage of slip and the amount of fusion. Post op follow up CT scan was taken at 6 months follow-up to document the quality of fusion. Operative technique was iliac crest bone harvest in supine and turned prone for the fusion and posterior instrumentation. The approach was a midline subperiosteal approach that involved laminectomy, foraminotomy. After adequate decompression the bed for the graft was prepared between the transverse processes and lateral aspects of the facet joints. Autograft from spinous processes and iliac crest was placed in this bed after stabilisation with pedicle screws and rods. Results: Statistical analysis using the students ‘t’ test proves the efficacy of posterolateral fusion in reducing the Oswestry clinical score and the radiological parameters. The fusion rate in PLF was 100% and there was no incidence of pseudoarthrosis in any of our cases. Conclusion: The simplicity of surgery, lower complication rate and the good results with regards to the clinical and radiological outcome in posterolateral fusion encourage its use when indicated in cases of degenerative and isthmic type of spondylolisthesis along with the use of adequate decompression and posterior instrumentation.

P142 - Degenerative Lumbar Scoliosis Treated With Polymethylmethacrylate Augmentation Of Bone Cement Injectable Cannulated Pedicle Screws

Haolin Sun¹

¹Peking University First Hospital, Beijing - China

Introduction: To describe the application of polymethylmethacrylate augmentation of cement-injectable cannulated pedicle screws for the treatment of degenerative lumbar scoliosis with osteoporosis. Methods: Retrospective cohort study was used to compared cement injectable cannulated pedicle screws (CICPs) group with PMMA augmentation and control group with traditional method in the correction surgery for Lenke-Silva level III and level IV degenerative scoliosis cases with osteoporosis. Both groups were followed up 1 year. The clinical results were assessed by visual analog scale (VAS) of pain on lumbar and lower limbers, Oswestry disability index (ODI) score and EuroQol-5 Dimensions (EQ-5D) score. The coronal major curve cobb angel in coronal plane and thoracic kyphosis cobb angle, lumbar lordosis cobb angle and sagittal vertical axis (SVA) in sagittal plane were test in whole long spine X ray. The fusion rates were evaluated by lumbar X ray and dynamic X ray. Results: 34 cases were enrolled in this study, 15 cases in CICPs group and 19 cases in control group. The general characteristics include age, gender, weight, height, BMI and BMD were without statistical difference between two groups. There were (5.7 ± 2.2) PMMA augmentation screws in CICPs group. The operation time, blood loss and blood transfusion were higher in CICPs than in control group but without statistical difference. Lumbar VAS, lower limbers VAS, ODI score and EQ-5D were all better when 1 month post-operation, 6 months post-operation and 1 year post-operation than pre-operation in both group. Lumbar VAS score of CICPs group when 6 months post-operation (CICPs group 3.1 ± 1.3 VS control group 4.4 ± 1.4, P < 0.01) together with lumbar VAS score (CICPs group 3.3 ± 1.0 VS control group 5.2 ± 1.4, P < 0.01), ODI score (CICPs group 22.7 ± 17.2 VS control group 31.4 ± 18.5, P < 0.01) and EQ-5D when 1 year post-operation (CICPs group 2.9 ± 2.0 VS control group 3.5 ± 2.5, P < 0.01) were lower than these of control group. The coronal major curve cobb angel were all lower when 1 month post-operation, 6 months post-operation and 1 year post-operation than pre-operation in both groups; thoracic kyphosis Cobb angle and lumbar lordosis cobb angle were all higher when 1 month post-operation, 6 months post-operation and 1 year post-operation than pre-operation in both group. The coronal major curve cobb angel was lower in CICPs group than that in control group 1 year post-operation (CICPs group 17.6 ± 6.9° VS control group 21.2 ± 7.2°, P < 0.01) and thoracic kyphosis cobb angle were higher in CICPs group than that in control group when 6 months post-operation (CICPs group -33.5 ± 8.8°VS control group -28.9 ± 8.3°, P < 0.01) and 1 year post-operation (CICPs group -33.0 ± 8.1° VS control group -26.3 ± 7.4°, P < 0.01) together with lumbar lordosis cobb angle were higher in CICPs group than that in control group 1 year post-operation (CICPs group 26.4 ± 8.1° VS control group 22.1 ± 7.3°, P < 0.01). Conclusion: Polymethylmethacrylate augmentation of bone cement-injectable cannulated pedicle screws for the treatment of degenerative lumbar scoliosis with osteoporosis was effective and safe. The short-term clinical result was good.

Keywords: cannulated pedicle screws,bone cement,osteoporosis,degenerative lumbar socoliosis.

P143 - Clinical Analysis Of The Complications Of Oblique Lateral Interbody Fusion (OLIF)

Feng Hailong¹, Liu Jinping¹

¹Department of Neurosurgery Sichuan Provincial People’s Hospital, Chengdu - China

Introduction: OLIF has been widely performed to achieve minimally invasive, rigid lumbar lateral interbody fusion. The associated perioperative complications are not yet well described This study aimed to explore the risk factors and prevention strategy of complications of oblique lateral interbody fusion (OLIF). Material and Methods: The clinical data of 67 cases of lumbar diseases treated with OLIF in the Neurosurgical Department of Sichuan Provincial People’s Hospital from December 2014 to December 2016 were retrospectively analyzed. Percutaneous pedicle screws or anterior vertebral screws were used for fixation in 18 and 26 cases respectively, OLIF stand alone were use in 23 cases. All of the intraoperative and postoperative complications were recorded. Results: Fifteen complications were recorded with an occurrence rate of 22.4%. Five of them are intraoperative complications including malpositioning of the cage in 2 case; transient thigh numbness weakness in 2 cases; sympathetic chain injuries in 1 case. There is no intraoperative major vascular injury and ureteral injuries. There were 10 postoperative complications including cage subsidence in 7 cases; fat liquefaction of incision in 2 cases; There is no surgical site infection. Conclusion: OLIF is a safe minimally invasive surgical approach for the treatment of lumbar degenerative diseases. The application of different fixation strategies combined with OLIF has essential impact on the complication rate. Strict patient selection and sophisticated surgical skills are keys to lower the complication rate.

P144 - The Correlation Between The Multifidus Muscle And Proximal Junctional Kyphosis After Long-Segment Instrumentation For Lumbar Degenerative Disease

Wenyi Zhu¹, Yong Hai¹

¹Department of Orthopedics, Beijing Chaoyang Hospital, Capital Medical University of China, Beijing - China

Introduction: Lumbar degenerative disease (LDD) is a common disease in middle-aged and elderly people. Pain and disability are the most relevant findings to take the decision of surgical treatment, Surgical treatment for patients with LDD often lead to one particular problem, which is proximal junctional kyphosis (PJK). We find lots of the risk factor for PJK, but ignore that muscle atrophy is also one of them. The purpose of our study was to use magnetic resonance imaging (MRI)-based assessments of the multifidus to predict the development of PJK. Materials and Methods: Lumbar degenerative disease patients (n = 62) who underwent surgery with minimum 2-year follow-up involving fusion of L5 and all the upper instrumented vertebra (UIV) in thoracolumbar spine(T9-L2), at a single centre between 2008 and 2014were retrospectively reviewed. All patients underwent standing radiographic imaging pre-operatively, immediately post-operatively, and at final follow-up. In addition, including pre-operative supine MRI. The patients were divided into PJK and non-PJK groups and subdivided into four groups by the UIV(T9-T12 vs. L1-L2). The demographic data included age, sex, and BMI. The MRI-based multifidus assessment was performed using ImageJ v1.4. Subsequently, the relative functional cross-sectional area (rFCSA) was calculated. Sagittal parameters were measured within the whole spine, using Surgimap v1.4. Results: PJK was observed in 22 of 62 patients (35%). Average follow-up was 34-months. There was a significant difference in the rFCSA between the PJK and non-PJK groups(p = 0.026). Patients who developed PJK comprised 37.5% of the L1-L2 group and 31.8% of the T9-T12 group, but there was not significant difference in the incidence of PJK. L1-L2 group show significant differences in age, rFCSA, lumbar lordosis, and global sagittal alignment (p = 0.047,0.001,0.041,0.016, respectively), between PJK and non-PJK. However, there were not difference in T9-T12 group. Conclusions: The rFCSA measured using MRI is the ratio that the pure muscle CSA and the same level disc CSA, and at the level of L4-5was an effective tool in predicting PJK after long-segment fusion for LDD, especially UIV in the lumbar spine.

P145 - Treatment In Disc Protusions With Adjacent Hernias

Carlos Mariano Nirino¹, Carlos Eduardo Nemirovsky¹

¹Department of Orthopedics and Traumatology, CMGSM, BS AS, Buenos Aires - Argentina

Introduction: The aim of this study is to describe the results obtained in relation to the moderate to slight protrusions at the L4/5 level with L5/S1 evident hernias in young patients. In all cases our behaviour is based on the temporary fixation post discectomy L5/S1 and L4/5 distraction. They were operated between January 2005 and December 2016 in our department of Orthopedics and Traumatology in Corporación Medica of General San Martin in Buenos Aires, Argentina. All patients were operated by the same surgical team including surgeon, assistants and surgical scrub nurse. In all of the surgeries we used the same surgical technique which consists in the L5/S1 hernia discectomy and then the transient fixation with the corresponding L4/5 distraction. Always remaining a fixation system of 3 lumbosacrals levels with 6 transpedicular polyaxial screws and 2 bars, which are removed at 6 to 8 months. The results are very good because of in more than 800 operated patients only in 2 cases we have had secondary disc protrusions treated with this method. When we removed the ostheosynthesis material at 6 to 8 months post surgical complete spinal mobility was restored; this as an established protocol of our department. Materials and Methods: More than 800 patients were evaluated. Only patients younger than 50 years old with an L5/S1 evident hernia and a L4/5 slight to moderate discopathy were considered. All patients were studied by Rx and MRI. All treated by the same surgeon, assistants and scrub nurse. Patients older than 50 years old and anyone who was performed to an arthrodesis were excluded from the present study.

Surgical technique: The technique consists on the transligamentary microdisectomy L5/S1 and the transient fixation with polyaxial transpedicular screws and bars at L4/5/S1 with the distraction of L4/5 in absolutely all cases. In none of them an arthrodesis is performed. Results: From all the cases, we have only had 2 with secondary protrusions in disks treated with simple distraction and both cases were in morbid obese patients, which we found very little significance.

We consider a strong need of treating both discs because leaving as a first mobile level a diseased disc, it potentially increases the risk of discopathies by addition. No patients required re operation, all returned to their daily lives in a few months. The following up on them was at least 2 years to 5 years in some cases. Conclusions: After an exhaustive study of each of our patients we conclude that it is always necessary to treat a diseased disc even though it is a slight to moderate protusion, especially if this is the adjacent disk to the discectomy that we had performed. This technique is always used in our department with which we do not have any type of complications and which gives us very good results.

P146 - Risk Factors For 90-Day Reoperation & Readmission After Lumbar Surgery For Lumbar Spinal Stenosis

Haariss Ilyas¹, Joshua Golubovsky², Jinxiao Chen³, Joseph Tanenbaum⁴, Thomas Mroz¹, Michael Steinmetz⁵

¹Center for Spine Health, Cleveland Clinic. Department of Orthopaedic Surgery, Cleveland, oH - United States ²Center for Spine Health, Cleveland Clinic. Cleveland Clinic Lerner College of Medicine, Cleveland, OH - United States ³Department of Epidemiology and Biostatistics, Case Western Reserve University ⁴Center for Spine Health, Cleveland Clinic. Department of Epidemiology and Biostatistics, Case Western Reserve University School of Medicine, Cleveland - United States ⁵Center for Spine Health, Cleveland Clinic. Department of Neurological Surgery, Cleveland, OH - United States

Introduction: Minimizing reoperations and readmissions after elective surgery represent an opportunity to optimize patient outcomes and simultaneously decrease the financial burden on the healthcare system. With discussion of an increased global post-operative period, the incidence and risk factors for 90-day readmission and reoperation warrant evaluation. Current literature supports a readmission rate of 3-9% after spine surgery. However, this literature is either limited to a 30-day window or does not stratify between different types of spine surgeries. Since lumbar spinal stenosis remains one of the leading indications for spine surgery, we felt it prudent to further evaluate this population. Therefore, this study evaluates the incidence and associated risk factors for 90-day readmission and reoperation after elective lumbar surgery for lumbar spinal stenosis. Materials and Methods: A retrospective consecutive cohort analysis of all patients undergoing posterior lumbar decompression with or without fusion for lumbar stenosis with claudication from January 2014 through December 2015 was performed. Statistical analysis was performed in RStudio. Multiple variable selection techniques were used to determine appropriate covariates for regression models, and logistic models were fit to assess for factors associated with reoperation and readmission. A further analysis was performed in a similar fashion assessing risk factors for surgical site infection. Results: Data was collected on 1592 consecutive patients. Among the sample population, the mean age at surgery was 67 (SD 10.1) and 45% of patients were female. The 90-day reoperation rate was found to be 5.5% (88/1592). 65% (57/88) of the reoperations occurred within the first 30 days, 26% (23/88) occurred between 31 and 60 days and 9% (8/88) occurred between 61 and 90 days. The 90-day readmission rate was 13.4% (222/1592). Multivariate analysis showed that a history of chronic obstructive pulmonary disease (COPD) (OR 1.583(1.117, 2.226), p = 0.009), congestive heart failure (CHF) (OR 2.173(1.372, 3.395), p = 0.001), diagnosis of surgical site infection (SSI) (OR 6.652(3.912, 11.290), p < 0.001), and discharge to a skilled nursing facility (SNF) from the index hospitalization (OR 3.699(2.643, 5.187), p < 0.001) were significant risk factors for readmission within 90 days. With regards to reoperation, a diagnosis of SSI (OR 24.492(13.939, 43.177), p < 0.001) and increased LOS (OR 1.240(1.168, 1.321), p < 0.001) were found to be significant factors. A subsequent analysis found that morbid obesity (OR 7.012 (2.653, 22.099), p < 0.001), history of coronary artery disease (OR 2.263(1.314, 3.850), p = 0.003) and increased duration of surgery (OR 1.004(1.001, 1.007), p = 0.008) were significant risk factors for developing a SSI. Conclusions: Overall, we found rates of 5.5% and 13.4% for reoperation and readmission within 90 days, respectively. 65% of the reoperations occurred within the first 30 days. A diagnosis of COPD, CHF, SSI and discharge to SNF from the index surgery were significant factors for readmission, while a diagnosis of SSI and increased LOS were found to be significant predictors for reoperation. Given the large impact of SSI, further analysis found that morbid obesity, a history of coronary artery disease, and increased duration of the index surgery were significant factors for developing a surgical site infection.

P147 - Preliminary Results Of Stand-Alone Alif Procedure In Patients With Lumbar Degenerative Disc Disease

Thomas D. Tilkema¹, Guido B. van Solinge¹, Adriaan K. Mostert¹

¹Department of Orthopaedic Surgery, Isala, Zwolle - Netherlands

Introduction: Surgical treatment in degenerative disc disease is controversial.¹ Several approaches have been used, with several different techniques.² We aim to determine the improvement in quality of life and vertebral stability in patients with lumbar degenerative disc disease (DDD), treated by single-level standalone anterior lumbar interbody fusion (ALIF) with the Chesapeake cage. Materials and Methods: In this prospective longitudinal cohort study, we aim to include a total of 80 patients. We report the preliminary results of 12 patients (mean age 48.3 years, male: female ratio 5:7); 10 patients at 1 year follow up and 2 patients at 6 months follow up. Patients with MRI confirmed single level degenerative disc disease were included, after failed conservative treatment. Patients were treated by a single surgeon. A single-level ALIF procedure with Chesapeake cage (K2 M) filled with a bone substitute (ActiFuse, Baxter Biosurgery) was performed on each patient. Outcome measures were Oswestry Disability Index (ODI), SF-36, Numeric Rating Scale (NRS) for back and leg pain to determine quality of life and pain, lumbar spine X-ray and CT-scan to determine fusion rates. Results: Pre-operative, 6 and 12 months follow-up questionnaire scores were available for 10 patients, 2 patients have pre-op and 6 months FU. CT scans are available for 10 patients. Mean preoperative NRS back pain score was 6.4 ( ± 2.4). At 6 months NRS back pain was 3.0 ( ± 2.0) and 3.4 ( ± 2.6) at 1 year, which is significantly lower (p = 0.008 and p = 0.02). NRS leg pain improved from NRS 6.5 (± 2.4) to 3.1 ( ± 1.9) at 6 months and 4.3 ( ± 3.1) at 1 year (p = 0.002 and p = 0.07). ODI significantly improved from a mean pre-operative score of 62.3 ( ± 13.5), to 40.4 (± 14.5) at 6 months and 41.8 ( ± 20.2) at 1 year (p = 0.001 and p < 0.02). EQ-5D and SF-36 improved slightly, although this was not a significant change. CT scans show fusion in 7 out of 10 patients 1 year after surgery. The non-fused patients had similar mean results on all questionnaires compared to the fused patients at 1 year after surgery. Conclusion: These data show promising results for the treatment of lumbar DDD by standalone single-level ALIF procedure with the Chesapeake cage. At 6 months after surgery, there is a significant improvement in pain scores as well as a clinically relevant improvement in the ODI. These results are stable at 1 year after surgery, except for the leg pain score which no longer showed a significant improvement. Surprisingly, the improvement in pain and disability did not result in significant improvements in quality of life scores. Fusion rates in the present patient population are acceptable. Interestingly, our data seem to confirm earlier findings on the lack of correlation between radiologic fusion and functional outcome after surgery.³ The single-level ALIF procedure with Chesapeake cage can provide significant improvement in clinical results in patients with lumbar DDD.

References

1. Fritzell P, Hägg O, Wessberg P, Nordwall A; Swedish Lumbar Spine Study Group. 2001 Volvo Award Winner in Clinical Studies: Lumbar fusion versus nonsurgical treatment for chronic low back pain: a multicenter randomized controlled trial from the Swedish Lumbar Spine Study Group. Spine. 2001 Dec 1;26(23):2521-32; discussion 2532-4.

2. Mobbs RJ, Phan K, Malham G, Seex K, Rao PJ. Lumbar interbody fusion: techniques, indications and comparison of interbody fusion options including PLIF, TLIF, MI-TLIF, OLIF/ATP, LLIF and ALIF. J Spine Surg. 2015 Dec;1(1):2-18.

3. Park Y, Ha JW, Lee YT, Sung NY. The effect of a radiographic solid fusion on clinical outcomes after minimally invasive transforaminal lumbar interbody fusion. Spine J. 2011 Mar;11(3):205-12.

P148 - The Effect Of Cigarette Smoking On Wound Complications After Single-Level Posterolateral And Interbody Fusion For Spondylolisthesis

Jonathan Nakhla¹, Murray Echt¹, Rafael De la Garza Ramos¹, Phillip Cezayirli¹, Andrew Kobets¹, David Altschul¹, Merrit Kinon¹, Reza Yassari¹

¹Department of Neurosurgery, Montefiore Medical Center, New York - United States

Introduction: Smoking is a universal public health concern that pose significant risks for surgical patients. The aim of this study was to evaluate the impact of smoking on the development of a wound complication, including wound dehiscence, superficial infection, deep infection, or organ space infection within the first 30 postoperative days in patients undergoing surgery for lumbar spondylolisthesis. Materials and Methods: Retrospective data from the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database for the years 2012 – 2014 were used to evaluate 30 day outcomes. Adult patients who underwent single-level posterolateral fusion (PLF) and posterolateral interbody fusion (PLIF) for spondylolisthesis were identified. Outcomes were compared between current smokers (within one year of surgery) and non-smokers. Results: A total of 1,688 patients who underwent single-level PLF or PLIF for spondylolisthesis were identified; 271 patients were current smokers (16.1%). The overall wound complication rate for smokers was 3.3% vs. 1.8% for non-smokers (p = 0.095). When stratified by operative technique, the rate of wound complications was not significantly different between smokers and non-smokers undergoing PLF (2.4% vs. 2.6%, p = 1.00); however, smokers who underwent PLIF were more likely to experience a wound complication compared to non-smokers undergoing PLIF (3.7% vs. 1.3%, p = 0.028). Conclusion: The findings of this study suggest that smoking may significantly increase the rate of wound complications after single-level PLIF but not necessarily after PLF for spondylolisthesis. The potential benefits of long-term fusion rates of placing an interbody must be weighed against the increased short-term rates of wound complications in patients that smoke.

P149 - Perioperative Complications In Elderly Patients Undergoing Single-Level Posterolateral Fusion Versus Interbody Fusion For Lumbar Spondylolisthesis

Jonathan Nakhla¹, Rafael De la Garza Ramos¹, Murray Echt¹, Adam Ammar¹, Yaroslav Gelfand¹, Andrew Kobets¹, Merrit Kinon¹, Reza Yassari¹

¹Department of Neurosurgery, Montefiore Medical Center, New York - United States

Introduction: To identify perioperative complications in the elderly undergoing single-level posterolateral fusion versus interbody fusion for spondylolisthesis. Materials and Methods: Retrospective data from the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database for the years 2012 – 2014 were used to evaluate 30 day outcomes. Adult patients who underwent single-level posterolateral fusion (PLF) and posterolateral interbody fusion (PLIF) for spondylolisthesis were identified. Outcomes were compared between current smokers (within one year of surgery) and non-smokers. Results: Between 2012 and 2014, 1,688 patients who underwent single-level PLF or PLIF for spondylolisthesis were identified from the ACS-NSQIP database. Among these, a total of 1,599 patients between the ages of 45 – 79 (94.7%) and 89 patients (5.3%) were 80 years or older. In the elderly group, there were 33 patients who underwent PLIF (37.1%). Overall, there were no significant differences in demographics or comorbidities between the PLF and PLIF groups. However, operative time was significantly longer for elderly patients who underwent PLIF vs PLF (3.0 ± 1.3 vs. 2.4 ± 1.0 hours, p = 0.036). In terms of 30-day outcomes, elderly patients who underwent PLIF had a higher complication rate (12.1% vs. 5.4%), though this did not reach statistical significance (p = 0.416). Similarly, readmission (6.1% vs. 5.4%, p = 1.00) and reoperation (3.0% vs. 0.0%, p = 0.371) rates were higher for PLIF vs PLF patients without reaching significance. Compared to middle-age patients, patients in the elderly group were significantly more likely to be hypertensive (80.9% vs. 59.8%, p < 0.001) and dependent (9.0% vs. 2.1%, p < 0.001) compared to younger patients. Similarly, a significantly higher proportion of patients in the elderly group were more likely to be ASA Class 3 – 4 compared to the younger group (67.4% vs. 47.4%, p = 0.002). On the other hand, middle-age patients were more likely to be smokers compared patients 80 years or older (16.8% vs. 3.4%, p < 0.001. In terms of operative parameters, middle-age patients were more likely to undergo interbody fusion (63.9% vs. 37.1%, p < 0.001) but also longer operative times (3.1 ± 1.4 hours vs. 2.7 ± 1.2 hours, p < 0.001). Length of stay was longer for elderly patients compared to younger patients (4.6 ± 4.2 days vs. 3.3 ± 2.8 days, p = 0.005). Lastly, perioperative complication (3.6% vs. 3.5%, p = 0.873), readmission (4.8% vs. 4.0%, p = 0.454), and reoperation (2.8% vs. 2.3%, p = 0.483) rates were not significantly different between the PLIF and PLF groups, respectively for patients aged 45 to 79. Conclusion: Octogenarians, although make up a smaller percentage of operative patients, are not at a higher rate of complication compared to their younger counterparts. The findings of this study may help spine surgeons and patients for preoperative risk stratification and perioperative expectations.

P150 - Extreme Lateral Interbody Fusion Restores Disc Hight And Achieves Nerve Roots Indirect Decompression: Long Term Functional And Radiological Outcomes

Salvatore Russo¹, Khai Lam²

¹Department of Neurosurgery, Imperial College NHS Trust, London - United Kingdom ²Department of Spine Surgery, London Bridge Hospital, London - United Kingdom

Introduction: Extreme lateral interbody fusion (ELIF) is a minimally invasive technique for anterior column stabilisation of the thoracolumbar spine. ELIF can decompress the nerve roots by disc height restoration and spinal segmental realignment. However, its efficacy in indirect decompression remains controversial. This study evaluates the long-term functional and radiological impact of ELIF in three different manifestations of lumbar disc degenerative disease: primary stenosis, spondylolisthesis and degenerative scoliosis. Materials and Methods: This study is a retrospective analysis of prospectively collected clinical and radiographic data of 105 consecutive patients operated with ELIF between 2012 and 2017. We included patients with radiculopathy associated with degenerative disc disease causing either primary spinal stenosis, spondylolisthesis or degenerative scoliosis. We collected clinical and radiological outcomes pre-operatively, immediately postoperatively, at 6 months and at last follow up. We measured average disc height, segmental angulation, lumbar lordosis, foraminal height, central canal and foraminal area using CT, x-ray and MRI. We evaluated functional outcomes by means of visual analogue scale for back pain and leg pain, Oswestry Disability Index and EQ-5D. Results: We performed 152 lumbar levels ELIF. 90.1% (137/152) had posterior stabilisation with bilateral pedicle screws. The primary diagnosis was lateral or central canal stenosis in 56% of patients, spondylolisthesis in 25% and degenerative scoliosis in 19%. The average follow-up was 13.6 months. Postoperative disc height, segmental angulation and lumbar lordosis improved respectively by 63%, 28% and 14% (p < 0.0001). Foraminal height and area increased by 25% and 52% respectively (p < 0.0001). The central canal area increased postoperatively by 44% (p < 0.0001.) All functional outcomes improved postoperatively (p < 0.0001). Visual analogue scale for back pain and leg pain improved by 60.6% and 74.6% respectively. Oswestry Disability Index and EQ-5D increased by 49.7% and 25.8% respectively. We recorded no significant changes at 6 months and last follow up for both functional and radiographic outcomes. Conclusion: To our knowledge, our study is the largest ELIF case-series that investigates long-term functional and radiographic outcomes in several manifestations of lumbar degenerative disc disease. In our study, ELIF restores intervertebral disc height, increases foramina and central canal areas and improves the sagittal alignment of the spine. Moreover, our study also demonstrates that ELIF achieves radiographically durable constructs, that ELIF is versatile in treating different degenerative conditions and that it allows long-term good functional outcome.

P151 - Physical Function Outcomes In Patients With Cardiopulmonary Disease Undergoing Lumbar Spinal Fusion

Jared C. Reese¹, Darrel S. Brodke², Ashley Neese², Yue Zhang³, Eli Bunzel¹, Mathieu D. Squires¹, Nicholas Spina²

¹School of Medicine, University of Utah, Salt Lake City - United States ²Department of Orthopaedics, University of Utah, Salt Lake City - United States ³Division of Epidemiology, University of Utah, Salt Lake City - United States

Introduction: The PROMIS^® Physical Function (PF) Computerized Adaptive Test (CAT) is an electronic questionnaire used to measure a patient’s physical function^[1]. Responses provide meaningful data for physicians to assess a patient’s physical competency before and after orthopaedic surgery, and has been validated in the spine population^{[2, 3, 4]}. However, the responsiveness of PF CAT scores to specific interventions within the lumbar spine and the effects of medical comorbidities on these scores have yet to be investigated. The purpose of this study is to evaluate the responsiveness of PROMIS PF CAT in single and two level lumbar fusions as well as the effects of cardiopulmonary comorbidities on these outcomes. Materials and Methods: A retrospective chart review was performed to identify patients who underwent a single or two level lumbar spine fusion between October 1, 2013 to June 1, 2017 at a single spine clinic. Patients were included if PF CAT and Oswestry Disability Index (ODI) questionnaires were completed at both pre- and post-operative time points. Patients were then stratified into two cohorts (either cardiac or pulmonary) based on ICD-9 and ICD-10 codes identified within patient records – such as CHF, arrhythmias, MI, emphysema, PE, and COPD. An adjusted linear regression model with mixed-effects was constructed to analyze PF CAT and ODI scores at preoperative, 3, 6, and 12 month time points. Results: Of the 972 patients identified (mean age 61, 48% male), 71 had a cardiac comorbidity and 79 had a pulmonary comorbidity. When adjusted for age, gender, and BMI, cardiac patients PF CAT scores ranked lower than non-cardiac patients at the preoperative, 3, 6, and 12 month time points (Cardiac: 42.9, 44.6, 44.9, 45.3; Non-Cardiac: 43.1, 45.5, 47,9, 47.8), with a significant difference found at the 6 month (p = 0.016) and 12 month (p = 0.003) time points. Cardiac patients ODI scores ranked higher than non-cardiac patients at all time points (Cardiac: 34.7, 31.9, 30.4, 23.0; Non-Cardiac: 31.9, 20.6, 15.5, 16.7), with a significant difference at the 3 month (p = 0.026) and 6 month (p = 0.021) time points. Pulmonary patients PF CAT scores ranked lower than non-pulmonary patients across all time points (Pulmonary: 41.0, 42.4, 41.5, 41.5; Non-pulmonary: 43.2, 45.7, 48.2, 48.1), with a significant difference found at the preoperative (p = 0.012), 6 month (p = 0.002), and 12 month (p < 0.001) time points. Pulmonary patients ODI scores ranked higher than non-pulmonary patients at all time points (Pulmonary: 37.0, 35.9, 31.5, 27.3; Non-pulmonary: 33.0, 21.7, 16.7, 17.8), with a significant difference found at the 3 month (p < 0.001), 6 month (p < 0.001), and 12 month (p = 0.014) time points. Conclusion: This study demonstrates a treatment response curve of physical function for lumbar spinal fusion over a one year period of time. In this cohort, cardiopulmonary patients improved less than the control group based on PF CAT and ODI metrics. Theses results suggest that the decreased responsiveness of improved physical function may likely be due to an individuals comorbidity. For these patient populations, adjusting treatment expectations based on PROMIS or assessing different outcomes, such as leg and back pain, may improve the evaluation of treatment efficacy.

References

1. Cella D, Riley W, Stone A, Rothrock N, Reeve B, Yount S, Hays R. (2010). The Patient-Reported Outcomes Measurement Information System (PROMIS) developed and tested its first wave of adult self-reported health outcome item banks: 2005–2008. Journal of Clinical Epidemiology,63(11), 1179-1194. doi:10.1016/j.jclinepi.2010.04.01

2. Brodke DJ, Saltzman CL, Brodke DS (2016). PROMIS for Orthopaedic Outcomes Measurement. Journal of the American Academy of Orthopaedic Surgeons,24(11), 744-749. doi:10.5435/jaaos-d-15-00 404

3. Hung M, Hon SD, Franklin JD, Kendall RW, Lawrence BD, Neese A, Brodke DS (2014). Psychometric Properties of the PROMIS Physical Function Item Bank in Patients With Spinal Disorders. Spine,39(2), 158-163. doi:10.1097/brs.0 000 000 000 000 097

4. Paulino Pereira NR, Janssen SJ, Raskin KA, Hornicek FJ, Ferrone ML, Shin JH, Schwab JH (2017). Most efficient questionnaires to measure quality of life, physical function, and pain in patients with metastatic spine disease: a cross-sectional prospective survey study. Spine J, 17(7), 953-961. doi:10.1016/j.spinee.2017.02.006

P152 - Negative Sagittal Balance: Elucidating The Opposite End Of The Spectrum

Wendy XP Lee¹, Nur Aida F Senan², Tiam Siong Tan¹, Ying Chyi Chong², Chung Chek Wong²

¹Department of Orthopaedic Surgery, Sibu Hospital, Sarawak, Malaysia, Sibu - Malaysia ²Department of Orthopaedic Surgery, Sarawak General Hospital, Kuching, Malaysia, Kuching - Malaysia

Introduction: Positive and negative sagittal balance have been so coined as to having the sagittal vertical axis (SVA) falling more than 4 cm ventral and dorsal to the posterior superior point of the first sacral end plate respectively. The bulk of the focus has been casted upon positive sagittal balance within the realm of lumbar degenerative kyphosis which is shown to correlate most highly with adverse health status outcomes. That said, overzealous attempts at restoring lumbar lordosis via posterior column osteotomies may inadvertently upturn the lumbar curve into a reversed alignment with consequent negative sagittal balance. Material and Methods: We illustrate a case of symptomatic L2-L3 adjacent segment degeneration post L3-L5 interbody fusion 5 years a priori. Cephalad L2-3 interbody fusion with posterior column osteotomies over L3-4, L4-5 ensued. Proximal junctional kyphosis with L2 pedicle screws pull-out alongside ventral one-third of L2 fracture were observed a month later. The construct was revised with cephalad extension of T11 pedicle instrumentations, T10 laminar hooks and L2 pedicle subtraction osteotomy-augmented by titanium mesh autologous grafting. Results: At presentation, the pelvic incidence measured 54°; segmental lordosis (L1-L2:2°; L2-L3:11°; L3-5:16°; L5-S1:10°). Following L2-L3 extension & PCO, total lumbar lordosis (54°) was adequate however in a reversed “J” lumbar alignment, (79.6 percent of overall lordosis being concentrated at upper lumbar fusion levels versus residual 20.4 percent at L5-S1). SVA post thoracic extension & L2 PSO measured -6.7 cm. Patient presented twelve months later with symptomatic broken rods at L2 with notable translation of the cranial over caudal lever arms, analogous to that of a chance fracture of an ankylosed spine. Of note, the thoracic segment demonstrated entity of diffuse idiopathic skeletal hyperostosis with contiguous flowing ossification anteriorly. Anterior column was revised minimal invasively utilizing tri-cortical iliac crest graft anchorage via anterior approach while new less contoured rods were exchanged posteriorly. Distraction force applied posteriorly across the previous L2 osteotomy site now loaded anteriorly with graft acted as fulcrum thus provided for a kyphosing counteraction of the pre-broken hyperlordotic state. SVA and lumbar lordosis measured 1 cm & 48 respectively. Fusion was observed 10 months later. Conclusion: Despite the relative adequacy of total lumbar lordosis via PCO in the first instance, the presence of segmental malalignment inadvertently reversed the lumbar lordosis, shifting the inflexion point of Roussouly cranially to involve the thoracolumbar junction and posteriorly. Posterior or negative imbalance is held to be generally well tolerated in part due to compensation by thoracic kyphosis. With undue regard to the inherently diminished compensatory capacity of an ankylosed thoracic spine coupled with the inverted lumbar malalignment, subsequent revision of the proximal junctional failure further exacerbated the extent of negative sagittal balance. Osteotomies when performed in the lumbar spine should account for the flexibility of the thoracic spine and more importantly, respect the “J” shape spatial organization of lumbar lordosis. Reversed lumbar lordosis in the face of a rigid thoracic spine can result in clinically significant negative sagittal balance. Anterior column shortening and posterior lengthening procedures are required to correct a negative sagittal balance spine.

P153 - Cauda Equina Syndrome; Early and Late Surgical Intervention and its Outcome? Case Series of 74 Patients at Tertiary Care Centre

Ashfaq Ahmed¹

¹Department of Orthopedics and Spine Centre, Ghurki Trust Teaching Hospital, Lahore - Pakistan

Introduction: Cauda equina syndrome (CES) is a severe neurologic disorder that can result from lumbar disc herniation with excessive compression on the cauda equina. More than 95% of uncomplicated herniated lumbar discs can be treated conservatively initially, with surgery reserved for patients who experience worsening of neurologic symptoms or failure to clinically improve after an appropriate conservative trial. In contrast, CES is a serious complication of lumbar disc herniation that requires an acute surgical decompression. Its clinical features can include severe low back pain, bilateral or unilateral sciatica, saddle anesthesia, motor weakness, sensory deficit, and urinary incontinence. It may progress to paraplegia and/or permanent incontinence. It is thought to be the primary absolute indication for the acute surgical treatment of lumbar disc herniation. Objective of the Study: The main objective of this study was to determine the outcome after the surgical intervention for cauda equine syndrome due to herniated lumbar disc in patients who were operated within 24 hours, those between 24-48 hours and after 48 hours. Materials and methodology: It was a retrospective as well as prospective study conducted from Jan 2006 to Dec.2016.74 Patients were enrolled in the study after fulfilling the inclusion criteria and after permission from the Hospital Ethical Committee as well as informed consent from the patients. All 74 patients excluding those who were lost in follow up, who presented with cauda equine syndrome in our unit, the records were taken from the hospital database and all the patients were called for follow up. The patients were divided into three groups, Group 1 include those who presented within 24 hr and operated same day, Group 2 include those who presented after 24 hr and within 48 hours and operated same day and Group 3 include those who presented after 72 hours. All the data was initially entered on preformed Performa and later on SPSS 17.0 was used for data analysis. Results: Among 74 patients, there were 54 (73.0%) males and 20 (27.0%) females with mean age of 38.49 ± 9.87 years and male to female ratio of 2.7:1. Only 1 patient was less than 15 years, 15 (20.3%) patients were between 15-30 years old, 46 (62.2%) were between 31- 45 years while above 45 years only 12 (16.2%). L5-S1 herniated disc was found in 35 (47.3%) patients, L4-L5 herniated disc was found in 29 (39.2%), L3-L4 level was found in only 3 (4.1%) and L2-L3 herniated disc was found in 4 (5.4%) patients. 49 (66.2%) have bilateral leg radiculopathy with absent reflexes, 12 (16.2%) having left side involvement, while 13 (17.6%) patients having right side involvement. Saddle anesthesia was found in all patients. 35 patients having urinary incontinence, 20 patients having urinary retention while 20 patients having no urinary problem.34 patients having bladder incontinence, 5 patients with constipation and remaining having no bowel problem. The follow up ranges from 1 year to 10 years with mean of 5.35 ± 2.7 years. 20 (27.03%) presented within 24 hr, 24 (32.43%) presented within 24-48 Hrz and remaining 30 (40.54%) presented after 48 hours. Improvement in pain and radiculopathy, saddle anesthesia, sexual power and return of bladder and bowel loss were same in Group I and Group II without any statistically significance. However significance were found after comparing it with Group III (p < 0.005). Only 2 patients having wound infection and 1 with dura tear. Which were managed accordingly. 3 patients from Group III having still on/off urinary incontinence and left leg weakness after 1 year follow up. 15 patients from Group III having still decrease sexual desire after last follow up. However it has been increasing with time. Conclusion: Emergent diagnosis and surgery will improve outcome, but improvement can be seen even in delayed cases. Awareness among general population is necessary for early visit to healthcare department after having symptoms of Cauda Equina is necessary for better results and early recovery of the patients.

P154 - Does The Morbidity & Mortality Justify Lumbar Fusion Surgery In Older Adults?

Maheswara Akula¹, Jetan Badhiwala¹, Fan Jiang¹, Yeswanth Akula², Chris Hulme³, Michael Fehlings¹

¹Department of Neurosurgery, Toronto Western Hospital, Toronto - Canada ²Brighton & Sussex University - United Kingdom ³Epsom General Hospital, Epsom - United Kingdom

Introduction: Low back pain and sciatica are increasingly common causes for disability in the elderly population, resulting in the incurrence of significant healthcare costs. A significant number of these patients are treated with instrumented posterior lumbar fusion. This systematic review and meta-analysis aims to evaluate the morbidity and mortality of lumbar spinal fusion in elderly patients in order to aid surgeons, anesthetists, and hospital administrators in planning intra- and post-operative care. Materials and Methods: This systematic review was performed in accordance with the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) Statement. An electronic literature search of the MEDLINE/PubMed, the Cochrane Library, EMBASE, and Scopus databases yielded 960 articles. These articles were screened against established eligibility criteria for inclusion into this study. For all meta-analyses, outcomes were pooled using the DerSimonian and Laird random-effects model, ¹ with weights calculated by the inverse variance method. Heterogeneity across trials was investigated by the Cochran Q test and measured by the I ² statistic, with I ² values exceeding 25%, 50%, and 75% representing low, moderate, and high heterogeneity, respectively.² Comprehensive Meta-Analysis version 2.2 (Biostat, Inc) was used to conduct all statistical analyses. Results: Our search strategy identified a total of 960 studies. Additional 28 studies were identified through by screening the references of relevant articles. After removal of 540 duplicate publications, the inclusion and exclusion criteria were applied to the titles and abstracts of the 448 articles. This yielded 51 articles that underwent full-text analysis. 24 articles of these were excluded. 27 articles were subjected to qualitative and quantitative analysis. Mortality rate was 2.5% (95% CI 0.9 to 6.6%). Mean estimated blood loss was 491.3 mL (95% CI 298.5 to 684.1 mL) and operative duration 195.5 min. (95% CI 162.7 to 228.4 min.). Incidence of Systemic complications were as follows: arrhythmia, 4.6%; CHF, 3.1%; pneumonia/respiratory distress, 5.4%; delirium, 7.1%; stroke, 2.1%; UTI, 5.0%; renal failure, 3.8%; DVT, 2.2%; PE, 2.7%; ileus, 7.1%; MI, 2.7%. SIADH, 1.8%; Spinal procedure related complications include neurological deficit, 3.6%; proximal junctional kyphosis, 4.0%; pseudoarthrosis, 8.5%; seroma/dehiscence, 3.7%; and wound infection, 4.2%; adjacent segment degeneration, 5.4%; dural tear, 6.7%; hardware failure, 2.8%; epidural hematoma, 5.0%. Conclusions: A shared decision making process between healthcare professionals and patients and family members is essential in offering lumbar arthrodesis to older adults. This study provides essential information to guide surgeons and anesthetists in planning intra- and post-operative care in this challenging demographic, and also his data informs healthcare policy makers considering the aging population.

P155 - Posterior Fixator Fusion Device In Degenerative Lumbar Spine Disease: Analysis Of Efficacy And Safety In A Series Of Patients With Lumbar Spondylosis Over A 3 – Year Period

Roberto Alfonso De Leo Vargas¹, Jaime Jesus Martinez-Anda¹, Ildefonso Muñoz-Romero¹

¹Neurological Center, ABC Medical Center, Mexico City - Mexico

Introduction: Lumbar degenerative disease (LDD) is a common and disabling condition that requires for surgical treatment adequate decompression of neural structures and stabilizing segmental instability. Lumbar pedicular screw fixation is the treatment of choice in cases of segmental instability. Interspinous rigid fixation has been attempted has a choice for degenerative LDD; we present the preliminary results of the experience with selective decompressive procedure and Interspinous fixation with Aspen^® Spinous Process Fixation System (Lanx Inc. Broomfield, Colorado) for patients with degenerative lumbar spine disease. Materials and methods: This is a case series of patients treated between March 2012 and October 2015 by senior author (R.dL.) at Neurological Center of American British Cowdray Medical Centre, in Mexico City. A prospective collection of clinical data of all patients with diagnosis of LDD was conducted. Inclusion criteria were: (1) radicular symptomatology and axial pain (2) single level lumbar degenerative disease, (3) lateral recess stenosis (4) intervertebral disc degeneration Pfirmann > 2. Exclusion criteria were: (1) high grade spondilolisthesis or rotational instability, (2) lumbar spine surgical background, (3) osteoporosis (4) lumbar fractures (5) fascetectomy > 1/3 during surgical procedure; epidemiological data, clinical background, operative findings, and clinical outcome were analyzed. All patients were treated surgically with radicular decompression at the level affected and interspinous rigid fixation with ASPEN® device; when disc degeneration was Pfirmman >4 and modic changes were also present, discectomy and posterior lumbar interbody fusion (PLIF) was also performed. Outcome was updated with the analysis of postoperative symptoms relief and recurrence, surgical complications, lumbar fusion, and reoperation rates. Statistical analysis was processed with SPSS 19.0; descriptive statistics were described for epidemiological and clinical data. Fisher Xi², Kruskall – Wallis proofs were run for univariate analysis. Results: One hundred and thirty patients were included, with a mean age of 51.7yo, female / male ratio of 1.1:1, mean body mass index (BMI) of 25.2, with 49.4% of patients having normal BMI. At preoperative evaluation patients had a visual analogue (VAS) and oswestry disability index (ODI) scales of 8.1 and 34.9 respectively. Levels affected were L4-5 (52.8%) and L5 – S1 (33.9%). Fifteen percent of patients required PLIF. Surgical complication rate was 3.8%, with 3 patients having postoperative neurological deficit, and 2 patients having surgical site infection (1.6%). Mean follow – up time was 22.4 months. Eighty seven percent of patients had significant clinical improvement. We found no statistical difference in clinical improvement between gender, lumbar level or procedure done. Re – operation rate was 9.2%, with a mean time of 16.5 months; indications for re-operation were: (1) interbody lumbar cage dislodge (16.7% of patients treated with PLIF + interspinous fixation, 2 patients), (2) worsen of clinical symptomatology (3%, 4 patients), and (3) adjacent segment disease (4.6% 6 patients). We performed a transforaminal lumbar interbody fusion (TLIF) and posterior pedicular fixation in all patients re-operated. Conclusions: Interspinous rigid fixation is a good surgical option for patients with 1 – level lumbar spondylosis, with lateral recess stenosis, without lumbar instability, having good clinical results and low complication rates.

P156 - Revision-Surgery After Lumbar Spinal Decompression - Is It Predictable?

Carolin Melcher¹, Alexander Paulus¹, Björn Roßbach², Christof Birkenmaier¹, Volkmar Jansson¹, Bernd Wegener¹

¹Department of Orthopedic Surgery, Physical Medicine and Rehabilitation, UNiversity Hospital LMU Munich, Munich - Germany ²Asklepios Klinik St. Georg, Department of Surgery, Section Knee, Shoulder and Elbow Surgery, Sports Traumatology, Hamburg - Germany

Objective: Surgical decompression is the intervention of choice for lumbar spinal stenosis (LSS) when non-operative treatment has failed. Same-level recurrent lumbar stenosis and adjacent-segment disease (ASD) are potential complications that can occur after index lumbar spine surgery. The aim of this retrospective case series was to evaluate whether revision surgery is predictable. Methods: Patients who had undergone either decompressive lumbar laminotomy or laminotomy and spinal fusion due to LSS between 2000 and 2011 were included in this analysis. Demographic, perioperative (blood loss, surgeon) and radiographic data were collected. Clinical outcome was evaluated using visual analog scale (VAS) scores, as well as (self-) reported ability to walk. Results: 338 patients underwent decompression surgery only, while instrumentation in addition to decompression was performed in 100 cases (22,3%). 69 re-operations (15%) were necessary after previous decompression/fusion with thirty-three percent (23/69) of reoperations for complications of the index operation (hematoma, infection). A new condition at the index or adjacent level accounted for 46 (67%) of all reoperations with incidence of 6,4% and 4,2% respectively. Pre-operative VAS score and ability to walk improved significantly in all patients.

Conclusions: No significant differences within the demographic, peri-operative and radiographic data of the decompression only and fusion groups were observed. Patients, who needed revision surgery were older but slightly healthier while more likely to be male and smoking. In summary, in this retrospective analysis we did not identify any parameters of a higher risk on revision surgery.

P157 - Applying Pmma As Custom-Made Intervertebral Spacer Is As Safe As A Standard Peek Cage In Mono-Segmental Tlif Complications At Minimum Two-Year Follow-Up Of A Prospective Randomized Clinical Study

Tibor Csakany¹, Maria Puhl¹, Marton Ronai¹, Peter Paul Varga¹

¹National Center for Spinal Disorders, Budapest - Hungary

Introduction: Although TLIF was designed to minimize the risk of injury to neural elements, there are still possible complications. Dural tear or nerve root lesion can happen while manipulating with the cage. Migration of the bone graft or spacer may result in nerve root compression, foraminal or spinal canal stenosis, etc. In a prospective randomized clinical study, we compared the radiological and clinical outcomes of mono-segmental TLIF using either a preformed commercially available PEEK cage or PMMA applied intervertebrally as a spacer. We present the complication rates of the two different methods at a minimum two-year follow-up of a prospective randomized clinical study. Material and Methods: 106 consecutive patients between 18-65 years of age, for whom a single level TLIF procedure was indicated, were included in the study. The patients were randomised into three groups by the GraphPad QuickCalcs software. Patients with a high-grade spondylolisthesis, metabolic bone disease, spinal infection, cancer, severe scoliosis (Cobb over 30°) were excluded. 8 patients were excluded because the operating surgeon did not follow the randomization for some surgical reason (i.e. not enough place for a spacer, injury of the end plate, etc.) Currently, the two-year follow-up ratio is 87%, 13 patients’ data are not available. Group A is standard TLIF with PEEK cage positioned in the anterior part of the intervertebral space (32 patients). Group B is standard TLIF with PMMA spacer placed in the anterior part of the intervertebral space (27 patients). Group C is standard TLIF with PMMA spacer formed in the posterior part of the intervertebral space (26 patients). Operation time, blood loss, dural tears, infection rate, subsidence, implant failure, reoperation and readmission rates, length of stay in the hospital were statistically compared among the patient groups. Results: There was no significant difference in the mean operation time (A:140, B:140, C:147 min) and blood loss (A:355, B:287, C:365 ml) between the three groups. There was no infection that required surgery in any groups. There was no dural tear in any groups. There was no difference in length of hospital stay in any groups. There was one case of an immediate postoperative neurological deficit in group B. There was significant difference in subsidence (A:10, B:2, C:2; p < 0.017), and no difference in implant failure (A:5, B:5, C:1). There were 6 reoperations for reasons related to index surgery (A:2, B:3, C:1) and 7 readmissions for conservative treatment during the follow-up period (A:3, B:1, C:3). Conclusion: These results show that complication rates of using PMMA as an intervertebral spacer are not different from those of a standard PEEK cage. Intervertebral application of PMMA might be a valuable alternative to cages in certain clinical situations.

P158 - The Number Of Features Present In Lumbar X-Ray Is Associated With The Intensity Of Pain And Severity Of Disability In Patients With Chronic Mechanical Low Back Pain

Romain Perera¹, Harsha Dissanayake², Upul Senarath³, Lalith Wijayaratne⁴, Aranjan Karunanayake⁵, Vajira Dissanayake⁶

¹Department of Allied Health Sciences, Faculty of Medicine, University of Colombo, Colombo 08 - Sri Lanka ²Department of Anatomy, Faculty of Medical Sciences, University of Sri Jayewardenepura, Nugegoda - Sri Lanka ³Department of Community Medicine, Faculty of Medicine, University of Colombo, Colombo 08 - Sri Lanka ⁴National Hospital of Sri Lanka, Colombo 10 - Sri Lanka ⁵Department of Anatomy, Faculty of Medicine, University of Kelaniya, Ragama - Sri Lanka ⁶Human Genetics Unit, Department of Anatomy, Faculty of Medicine, University of Colombo, Colombo 08 - Sri Lanka

Introduction: Disc space narrowing, anterior osteophytes and lumbar spondylolisthesis are the main x-ray features of degenerative lumbar spine. These x-ray features are common findings in patients with chronic mechanical low back pain. Most of the previous studies have investigated the association of individual x-ray features with the symptoms of chronic low back pain, but their associations are weak. The main aim of this study was to assess the association of number of x-ray features with the intensity of pain and severity of disability in patients with chronic mechanical low back pain. Material and Methods: A cross-sectional study was conducted on 439 patients with chronic mechanical low back pain who attended the rheumatology clinic, National Hospital of Sri Lanka, Colombo from May 2012 to May 2014. Presence of disc space narrowing, anterior osteophytes and spondylolisthesis were assessed in lateral lumbar x-rays (L1/L2 to L5/S1) and reported by a consultant radiologist blinded to clinical details. An aggregate x-ray score was calculated for each patient by summing the number of x-ray features present in each patient. Intensity of pain was assessed using numeric rating scale (0 –100) and the severity of disability was measured using Modified Oswestry Disability Index. Multivariable generalised linear model with linear response was used to assess the association of individual x-ray features/ aggregate x-ray score with the intensity of pain and severity of disability adjusting for age, gender, body mass index (BMI) and pain radiating into legs. Results: Mean age was 48.99  ±  11.21 and 323 (73.6%) were females. BMI was 26.39  ±  4.65 and 87 (19.8%) were obese. In addition, 110 (25.1%) patients had pain radiating into legs. Mean intensity of pain was 45.50  ±  20.37 and mean severity of disability was 30.95  ±  13.67. Among patients, 176 (40.1%) had disc space narrowing and 201 (45.8%) had anterior osteophytes. Lumbar spondylolisthesis was present in 51 (11.6%) patients. The number of patients with 0, 1, 2 and 3 of these x-ray features was 159 (36.2%), 154 (35.1%), 104 (23.7%) and 22 (5%), respectively. Presence of anterior osteophytes was associated with intensity of pain (β = 4.6, p = 0.02) while presence of lumbar spondylolisthesis was associated with severity of disability (β = 5.7, p < 0.01). Patients with two and three x-ray features had higher intensity of pain compared to the patients with no x-ray features (β = 6.8, p = 0.02; β = 9.4, p = 0.04, respectively). Furthermore, patients with three x-ray features had increased severity of disability compared to the patients with no x-ray features (β = 8.1, p = 0.01). Female gender and pain radiating into legs increased the intensity of pain and severity of disability (p < 0.01). In addition, advancing age reduced the intensity of pain (β = -0.27, p < 0.01). Conclusion: Intensity of pain and severity of disability increased with the number of x-ray features present in patients with chronic mechanical low back pain. Female gender and pain radiating into legs are significant confounders.

P159 - Pseudarthrosis As The Cause Of Instability Of Pss After Tlif And Plif Operations

Vladimir Porhanov¹, Igor Basankin¹, Sergey Malahov¹, Asker Afaunov¹, Vladimir Shapovalov¹, Alexey Mishagin¹, Karapet Tahmazyan¹, Alexandr Krik¹, Alexandr Kuzmenko¹, Marina Tomina¹, Pavel Nesterenko¹, Alexey Volinnskiy¹

¹Research Institute, Krasnodar Regional Hospital 1, Krasnodar - Russian Federation

Introduction: Back decompressive-stabilizing operations such as TLIF and PLIF are often used in to treat degenerative diseases in the lumbar spine. However, the application of these technologies is sometimes associated with formation of pseudoarthrosis in the operated area and PSS instability in a long-term period. Material and Methods: 1822 operations for spinal stenosis, spondylolisthesis and instability using PSS were performed during the period 2012-2014 in our department. Of these 1513 were TLIF and 309 were PLIF. Open surgical technique was used in 1567 (86%), minimally invasive technique with using of retractors was used in 255 (14%). The age of the patients was 21-76 (average 61). Men - 42%, women - 58%. One-level fusion was performed in 1308 (71,8%) patients, 2-level - 419 (23%), 3-level and more - 94 (5,2%). In total 2012 segments were operated, L5-S1 - 677 (33,7%), L4-L5 - 828 (41,3%), L3-L4 - 279 (13,9%), L2-L3 - 228 (11,1%). TLIF and PLIF PEEK cages were implanted in 1730 (86%) and titanium banana-like cages were implanted in 282 (14%). All operations were performed by five surgeons of the same department. The patients were examined at 3, 6, 12 months and in case of any problems. Results: In the 3-month interval after the operation 1547 (85%) patients were examined, in the 6-month after the operation - 1367 (75%), 1129 (62%) in a year. Bridwell scale (1995) was used to evaluate the fusion. One year after the surgery 1 grade fusion was noted in 854 (75,7%), 2 grade - 192 (17%), 3 grade - 60 (5,3%), 4 grade - 23 (2%). Instability of the PSS was detected in 24 (2.12%) patients. A fracture of the elements of PSS was detected in 5 (21%) patients (mostly young patients). In other 19 cases (79%) patients had instability due to resorption of the bone around the screws (mainly elderly patients). PEEK cages were installed in 21 cases as an interbody implant - 1.21% of the total number of implanted PEEK cages. In three other cases pseudarthrosis was formed after implantation of titanium cages - 1.06% of the total number of implanted titanium cages. All 24 patients with PSS instability had 3 grade and 4 grade fusion. Most often pseudoarthrosis and PSS instability occurred in L5-S1 segment - 11 cases (45.8%), L4-L5 - 7 cases (29.1%), L3-L4 - 4 cases (16.6%), L2- L3 - 2 cases (8.3%). Some of the patients with 3 grade fusion had micro-resorption of bone tissue, but did not require revision surgery at the time of the examination. 1 and 2 grade fusion had no signs of PSS destabilization. Conclusion: The existing fusion ensures the stability of PSS. The cause of PSS destabilization is pseudoarthrosis in the area of the performed spondylodease. The formation of pseudoarthrosis does not depend on the material of the implanted cage. The greatest amount of pseudarthritis is noted at level L5-S1.

P160 - Analysis Of Complications Of Surgical Teatment Of Degenerative Stenosis

Igor Basankin¹, Asker Afaunov¹, Vladimir Shapovalov¹, Alexandr Kuzmenko¹, Sergey Plyasov¹, Marina Tomina¹, Karapet Tahmazyan¹, Sergey Malahov¹

¹Research Institute Krasnodar, Regional Hospital 1, Krasnodar - Russian Federation

Introduction: lumbar degenerative stenosis is one of the most common pathologies of the spine. This disease often requires surgical treatment using PLIF and TLIF technologies. Material and Methods: Our study includes surgical treatment of 511 patients (306 women, 205 men) aged 23-74 years with degenerative lumbar stenosis. Patients were operated between 2009-2013. The study included 415 patients were operated primary (81.21%) and patients with revision after a microdiscectomy - 96 (18.79%). Results: Short-term results of treatment for 2-3 months after surgery were studied in all patients. The desired result of treatment was achieved in 498 (97.45%) patients. Various complications were found in 57 (11.15%) patients. There were complications of early period such as: liquorrhea - 20 patients (3.91%), surgical wound abscess - 10 (1.95%), retention or worsening of radiculopathy - 21 (4.1%), postoperative hematoma - 3 (0.58%). Surgical treatment of complications was required in 15 (2.93%) patients. 3 patients (0.58%) had a fatal outcome due to the development of pulmonary embolism and multiple organ failure. Long-term results were followed by 2 years in 314 (61.4%) patients. Revisions were performed in 63 (12.32%) patients. All revision surgery we took over 100%. Causes of revision surgery were: the destabilization of the caudal screw of spinal system in 19 (30.15%) patients; destabilization of the cranial screw in 12 (19.04%) patients; recurrent radiculopathy due to the development of epidural scar-adhesive processes in 11 (17.4%) patients; the progression of the degenerative processes above the level of fixation in 6 (9.52%) patients; fractures of cranial or caudal screw in 6 (9.52%) patients; screw’s connector unlock in 2 (3.17%) patients; formation of interbody pseudarthrosis in 4 (6.34%) patients; late abscess in 3 (4.76%) patients. Summing up all the complications after surgery we found that after 1 level TLIF - 2.12% of revisions, 2 levels - 6.86% of revisions, 3 levels and more - 32.29% of revisions

Conclusion

1. The most common reasons for revision surgery in the early postoperative period were local wound complications (2.93%). The most common causes of these occurred in patients were previously operated in the same field and in cases of extended operations.

2. Revisions of the late period are mainly associated with the formation of unstable or broken metal (61.88%), as well as the progression of the degenerative processes (15.86%).

3. We found a clear correlation between the number of TLIF levels and revision surgery. The more extensive decompression and fixation is the higher probability of reoperation can be

P161 - Surgical Treatment Of Symptomatic Sacral Perineural Cyst (Tarlov Cysts): A Study Of 16 Cases And Review Of The Literature

Marco Locatelli¹, Mario Zavanone¹, Mauro Pluderi¹, Daniele Nicoli¹, Paolo Rampini¹

¹Department of Neurosurgery, Policlinico di Milano, Milan - Italy

Objective: Tarlov or perineural cysts (TC) are lesion of the nerve root most often found in the sacral region. Given the low estimated rates of symptomatic TC and the fact that symptoms can overlap with other common causes of low-back pain, optimal management of this entity is a matter of ongoing debate. The aim of this retrospective study is to investigate the outcome of 16 consecutive patients treated by surgical excision of the cyst along with duraplasty and to review the literature. Methods: The authors retrospectively reviewed their clinical data archive from January 2004 to March 2017. Sixteen patients who were operated with unique surgical method on due to symptomatic sacral perineural cysts were enrolled in the study. The pain severity was assessed according to visual analog scale (VAS), and imaging changes were evaluated by magnetic resonance imaging (CT-MRI). Patient improvements in pain and neurologic function were evaluated during a follow-up the period of 14 months to 13 years. Results: There were 2 men and 14 women included in the study. Preoperative symptoms include low back pain, sacroiliac pain, perianal pain, radicular pain, motor deficit, postural aggravation and bladder dysfunction. All of the patients underwent surgical excision of the cyst along with duraplasty. All the patients experienced complete or substantial resolution of the preoperative radicular pain and bladder dysfunction after surgery. Neither new postoperative neurological defects, infection nor cerebrospinal fluid leakage were observed in our series. In the literature, there are six different treatment options under debate and controversially discussed. Conclusions: Surgical excision of the cyst along with duraplasty is a feasible approach in the operative treatment of this difficult, and often controversial, spinal pathology. The data suggest that patients with symptomatic TCs may experience a long term benefit from open surgical treatment.

P162 - Elective Spine Surgery For Patients Older Than 90-Years Old: Is 90 The New 80?

Ehab Shiban¹, Paulina Rothlauf¹, Bernhard Meyer¹

¹Department of Neurosurgery, Technical University of Munich, Munich - Germany

Introduction: Demographic trends make it incumbent on spine surgeons to recognize the special challenges involved in caring for older patients. Aim of this study was to identify variables that may predict early mortality in geriatric patients over the age of 90. Material and Methods: Retrospective analyses of all patients over the age of 90-years, which were treated between 2006 and 2014 at our department for degenerative spine disease, were performed. Patient characteristics, type of treatment and comorbidities were analyzed with regards to the 30-day mortality rate. Results: 25 patients were identified. Mean age was 92.8 years (range 91-101), 21 (84%) patients were female. 16 (64%) patients were on anticoagulation therapy. 17 (68%) patients were treated operatively. Mean Hospital stay was 14 days (range 2-40). Mean Charlson comorbidity index was 5.5 (range 0-12) and mean diagnosis count was 12 (range 2-24). The 30-days mortality rate was 17% in the surgically treated group compared to 0% in the conservatively treated group (p = 0.2). Gender (p = 0.42), diagnosis count (p = 0.65), Charlson index (p = 0.65) and anticoagulation therapy (p = 0.9) did not correlate with the 30-day mortality rate. Cause of death was pulmonary embolism in two cases and was unknown in one case. Conclusion: 30-day mortality rate in patients over 90-years-old following elective spine surgery is very high. Standard geriatric prognostic scores seem less reliable for these patients. Prospective validations studies are needed in order to establish treatment recommendations for such patients.

P163 - Novel Technique In Combining Autograft Iliac Crest And Allograft In Anterior Lumbar Interbody Fusion (Northumbria Technique)

Ata Kasis¹, Rahul Dharmadhikari², Matthew Mawdsley¹, Cyrus Jensen¹

¹Department of Trauma and Orthopaedics, Northumbria Healthcare NHS Foundation Trust, Ashington - United Kingdom ²Department of Radiology, Northumbria Healthcare NHS Foundation Trust, Ashington - United Kingdom

Introduction: Due to the significant shortage of Bone Morphogenic Protein (BMP-2) in Europe at the beginning of 2016, a new technique was developed to combine the osteoconductive, osteogenic and osteoinductive properties of bone grafts. Prior to 2016, a combination of fresh frozen femoral head (FFFH) (osteoconductive) and BMP-2 (osteoinductive) was used inside the fusion cage, with excellent results. The technique involved inserting BMP-2 into two drill holes inside the FFFH, a technique adopted from Gold Coast Spine, Australia. We describe a new technique of replacing the BMP-2 with a core of cancellous iliac crest bone autograft, obtained using a cannulated core biopsy needle. Inserting this autologous cancellous bone core inside a drilled tunnel in the cancellous FFFH allograft added osteogenic and osteoinductive properties to the structural osteoconductive FFFH graft. The fusion was assessed using fine cut CT scan. To our knowledge this technique has not been described before. Material and Methods: This is a prospective review of 50 consecutive patients (total 53 levels fused) who underwent Anterior Lumbar Interbody Fusion (ALIF) between 2016-2017. All patients had a routine fine cut CT scan at 4-5 months post-operatively to assess for fusion. The CT scan was reviewed by a consultant radiologist to assess the presence of fusion. All patients had ALIF at L4/5 and/or L5/S1 using a Brantigan® cage and Aegis® plate (Depuy-Synthes). A combination of FFFH allograft and iliac crest core autograft were used. Two blocks of cancellous FFFH allograft were cut to the size of the graft windows using an electric saw. A core of cancellous iliac crest bone was inserted through a drill hole in the middle of each block of FFFH. The autograft was obtained from the left iliac crest through a stab incision in the skin. Once the 10 gauge Stryker® biopsy needle was through the cortical bone, the stylet was removed and the needle advanced 4-5 cm, continuously rotating the needle. Results: 50 consecutive patients who underwent ALIF procedures for degenerative conditions were included. There were 32 females. The mean age was 44.2 (33.6-70.3) years. 29 patients had surgery at L5/S1, 18 patients at L4/5 and 3 at L4/5 and L5/S1. 11 patients had surgery for spondylolisthesis, 14 for recurrent disc prolapse, 20 for neuroforaminal stenosis due to significant loss of disc height, and 5 for DDD. There was radiological fusion in 49 patients (52 levels) (98%), and non-union in one. The patient who had radiological non-union was a 42 year old female, non-smoker, and had surgery for DDD. There were no complications at the donor site (pain or infection). There was no VTE, and no intra-operative complications. The average blood loss was 90 mls (40-160 mls). Conclusion: Combining iliac crest cancellous bone autograft, obtained through a minimally invasive technique, with cancellous allograft is effective with good union rate (98%), without complications from the donor site.

P164 - Extreme Lateral Interbody Fusion (Xlif) In Lumbar Degenerative Spondylolisthesis Of Grades I And Ii

Riccardo Iundusi¹, Federico Mancini¹, Pasquale Farsetti¹, Umberto Tarantino¹

¹Department of Orthopaedics and Traumatology, University of Rome “Tor Vergata”, Rome - Italy

Introduction: Extreme lateral interbody fusion (XLIF) is by now a well-documented technique for vertebral arthrodesis, performed to increase lordosis and to decompress nerve structures. This minimally invasive technique is also used to treat degenerative spondylolisthesis (DS) but, especially in cases with more than 25% slip, its suitability could not be such as to recommend its use. The aim of the study was to evaluate the XLIF feasibility, safety and effectiveness in a group of patients with degenerative spondylolisthesis of grades I and II. Material and Methods: In a group of 53 patients with DS treated of decompression and lumbar arthrodesis, 18 cases were treated with XLIF and posterior arthrodesis (PA) reaming the facet joints before percutaneous pedicle screws insertion in the lower level of DS, 20 with TLIF and PA with pedicle screws and 15 only with posterior instrumentation. In 18 cases of XLIF the mean age was 66 years (range 47-75) and 12 were females, 3 of these patients had already undergone lumbar microdiscectomy. In cases treated with XLIF, the DS of Grade I and Grade II was present respectively in 13 and 5 patients. We evaluated the pre- and postoperative clinical condition of the lumbar spine and lower limbs using Oswestry Disability Index and Visual Analogue Scale, detected co-morbidities, and performed radiological investigations with X-rays, MRI and CT-scans at 3, 6 and 12 month follow-up. Disc height, amount of anterolisthesis, lumbar lordosis, pelvic incidence and pelvic tilt, and degree of pre- and postoperative disc degeneration of adjacent levels were measured; the degree of fusion achieved at least at one year follow-up was assessed according to the Bridwell’s classification. Results: 18 levels were performed using XLIF (12 levels at L4-L5, 5 at L3-L4, 1 at L2-L3); in all cases intraoperative neuromonitoring was used as required by the technique. Titanium cage was used in 12 patients and PEEK cage in the others. Two cases of transient neurologic deficiency occurred and a new direct decompression was needed in a patient with persistent symptoms. At last follow-up, an average of 6 mm improvement in disc height was observed, anterolisthesis decreased of about 70% and lumbar lordosis increased of 10°; 2 cases showed less than 2 mm of subsidence; all cases were fused after one year. VAS decreased from 8.2 to 2.0 for the lumbar spine, from 4.4 to 1.4 for lower limbs, and ODI improved from 48.6 to 24.4 at 12 month follow-up. The average length of hospitalization was 3.2 days. Conclusion: XLIF showed an excellent reduction of spondylolisthesis and an important increase in disc height even in cases of SD grade II. These aspects at the basis of indirect decompression, associated with increased lumbar lordosis, contributed to improve the sagittal balance of the spine by favoring a good clinical and radiographic result at 1 year follow-up. Given the low number of perioperative complications, XLIF represents an effective and safe minimally invasive technique for treating DS even for anterolisthesis of Grade II.

P165 - Treatment Of Degenerative Lumbar Stenosis By Decompression With Sublaminar Osteotomy: A Technical Note

Vincent Lamas¹, Etienne Laloux²

¹Department of Orthopaedic Surgery, CHU Dijon, Dijon - France ²Spine Surgery, Dijon Bourgogne Private Hospital, Dijon - France

Introduction: Lumbar spinal stenosis (LSS) is the most frequent indication for spinal surgery in 65-aged patients and older. The ligamentum flavum is involved in the narrowing of the vertebral canal, and the compression of intra canal vascular and nervous structures. The issue of surgical treatment of LSS is to perform an efficient and lasting removal of the compression causes while avoiding per and post-operative complications such as iatrogenic instability. Material and Methods: We describe a technique for lumbar recalibration in symptomatic LSS without pre-operative radiological instability, in which is performed a sub-laminar osteotomy not yet quoted in the literature. The recalibration is similar to the technique described by Senegas, then we perform a sub-laminar osteotomy by positioning a bone chisel through the inter laminar space previously widened. The axis of the osteotome is introduced into the spongy bone of the lamina, between its external and its internal cortical bone. Thus, the lamina is cut into two parts in its thickness, until it is possible to extract a monobloc sub-laminar piece including the insertion of the ligamentum flavum. Results: Consequently, the dura mater and the roots are uncompressed whilst we preserve the caudal portion of the posterior arch and the major part of the posterior articulations. Conclusion: By lowering considerably the osteosynthesis’ adjacent segment degeneration problems, and by avoiding side-effects due to laminectomy, this technique seems to be a simple, efficient, lasting and reproducible method.

P166 - Surgical-Outcome For Lumbar Spinal Stenosis In The Elderly: Quality Of Life, Pain, Fear Avoidance Beliefs And Activity Of Daily Living Of Patients Ages 65 Years And Older

Babak Babak Mirzashahi¹, Fatemeh Mirbazegh²

¹Joint Reconstruction Research Center, Department of Orthopedic Surgery, Imam Complex Hospital, Tehran University Of Medical Sciences, Tehran - Iran, Islamic Republic ²Tehran University of Medical Sciences, Tehran - Iran, Islamic Republic

Introduction: Degenerative lumbar spinal stenosis is increasingly being diagnosed in persons over age 65. Surgery is common treatment in this case but there are raised questions about the outcome of surgery in older patients. The purpose of this study was to analyze surgical results based upon standardized tools, before and after surgery of lumbar spine stenosis among of patients ages 65 years and older. Method: All patients being 65 year or older, who underwent lumbar spine surgery at one spine center, utilizing a variety of surgical techniques, enrolled in this study. Demographic data, procedures, perioperative comorbidities, preoperative and postoperative pain intensity, basic activities of daily living, quality of life, fear avoidance were collected at baseline and all of patients were followed at least 12 months after the operation. Results: A significant reduction in VAS, FAB (P < 0.001) and a significant increase in SF-36index and the Barthel index (P < 0.001) were recorded. Conclusion: Surgery in elderly patients is effective in the treatment of spinal stenosis, who did not respond well to the conservative treatment. Most of the patients benefited from the surgery in terms of reduction in pain and fear, increase in ADL and quality of life.

P167 - Result using of Full-Endoscopic System for Decompression of Nerve Structures on Lumbar Level of the Spine. Report of First Experience

Vasiliy Korolishin¹, Nikolay Konovalov¹

¹Department of Spinal Neurosurgery, NN Burdenko Neurosurgical Institute, Moscow - Russian Federation

Introduction: A lot of effective methods of decompression of structures in channel in spine are used in the modern medicine. Whole experience of authors contains 161 patients, who underwent full endoscopic lumbar procedure in two centres. For 151 consecutive patients was used sequesterectomy only and 10 patients with central or foraminal stenosis underwent transforaminal or interlaminar decompression. This presentation reviews a private experience of using of full-endoscopic uniportal sequesterectomy for decompression of nerve root in lumbar region in retros pective cohort evaluation. Materials and Methods: We utilized transforaminal and interlaminar approach for patients with disc herniation. First 44 patients were operated by interalaminar endoscopic approach, all patients had L5-S1 disc herniation, next 107 patients were operated by transforaminal approach. Among them 59 patients had disc herniation on L5-S1 level, 42 on L4-L5 level, 5 on L3-L4 and 1 patient on the L2-L3. Summarized 152 patients with different location of pathology were undergone 154 operations (1 patient had pathology on two levels, 1 underwent repeat surgery due to lost fragment in first hour). Pre- and post- operating examination included scoring by visual analogue scale (VAS), Oswestry Disability Index (ODI), evaluation of operation time, MacNab evaluation. Result: Before the operation data of all patients have been calculated with using of scales and questionnaires. Mean ODI was 50 ± 7% (min 40, max 70, mode 50), mean VAS₁ (back pain) – 6 (min – 1, max 10, mode - 9), mean VAS₂ (leg pain) was 8 (min – 5, max 10, mode - 9). Mean follow up was 13,6 months (min 4, max 47, mode - 4). Survey has been carried every 3 months after surgery, but this presentation demonstrates the latest data. Postoperative data showed that mean ODI decreased to 8,31 ± 1,53% (min 5, max 10, mode – 10). All of patient noted improve their pain status. Mean VAS₁ improved to 0.98 ± 0,02 and VAS₂ for 0.18 ± 0,3. Evaluation of MacNab's significances showed that 73 (48%) patients considered result of surgery as «good», 42 (28%) evaluated result as excellent, 35 (23%) - fair. The mean of operation time was 71 minutes (min – 30, max – 130, mode – 60 min). Conclusion: Utilization of full endoscopic system in routine practice became good alternative to microsurgical method of disc herniation removing. Improvement of visualisation of instruments under the nerve root supports increasing of quantity “best result” of surgery via improving of quality of decompression of nervous structures.

P168 - Degenerative Lumbar Canal Stenosis And Surgical Therapy - Long Term Postoperative Clinico-Functional Analysis

Siva Subrahmanyam Chivukula¹, Prasad Bcm¹, Chandra Vvr¹

¹Dept. Of Neurosurgery, Sri Venkateswara, Instiute of Medical Sciences, Tirupati - India

Introduction: Lumbar spinal stenosis (LCS) is a frequent indication for spinal surgery and the clinical symptoms may not be accurately reflected on radiological studies. Treatment is aimed at not only obtaining immediate pain relief but also to prevent long term disabling sequelae. Walking ability needs to be correlated with functional outcome measures in assessing patients with symptomatic lumbar canal stenosis.The aims To study and evaluate outcome of surgery for degenerative lumbar canal stenosis (LCS) on a clinical, radiological and functional basis and to establish an association between various influential factors related to lumbar canal stenosis. Material and Methods: Prospective study of 60 patients in the Department of Neurosurgery, SVIMS, Tirupathi, whose LCS confirmed and measured on MRI images by thecal sac cross sectional area (CSA) and Functional assessment done by motorised treadmill test for First Symptom Time (FST) and Maximum Walking Distance(MWD), Visual Analogue Scale (VAS), Oswestry Disability Index (ODI), Japanese Orthopedic Association (JOA) score and Short Form-36 (SF-36) score. Results: Pre and postoperative VAS, ODI, JOA, SF-36 scores showed significant improvement. Postoperative thecal sac measurements showed a significant neural decompression substantiating the results of improvement in the functional assessment scores after surgery. Treadmill test is a quantifiable means of dynamic function, considered as a tool of assessing the functional impairement and correlated with CSA of stenosis. Persistence of postoperative relief was partial to complete over a long term follow-up. Conclusions: A combination of functional scores, treadmill test and thecal sac CSA can be included in the preoperative assessment of outcome in patients with LCS.

P169 - Influence Of Total Hip Arthroplasty On Sagittal Lumbo-Pelvic Radiographic Parameters

Emiliano Vialle¹, Luiz Roberto Vialle¹, Saulo Miranda¹

¹Cajuru Hospital, Catholic University of Parana, Curitiba - Brazil

Introduction: Sagittal Balance (SB) is defined as the biomechanical relation of the sagittal axis of the spine to the pelvis. Changes in the sagittal axis of the spine or hip are capable of influencing the entire SB complex, thus, severe coxarthrosis and total hip arthroplasty (THA) present as potential modifiers that can alter SB, and are responsible for low back pain or symptomatic relief of this. Objective: To prospectively analyze the radiographic variables of the Lumbosacral Sagittal Balance (LSB) in the pre and postoperative period of patients submitted to THA. Material and Methods: A prospective, observational, comparative study that evaluated pre and postoperative radiographic parameters of 71 patients, submitted to 72 ATQs in a 3-year period (2014-2017) for primary coxarthrosis, of whom 28 performed late postoperative control (6 months) through the Surgimap Spine program. Statistical analysis was performed using the Student’s t-test, the covariance analysis model (ANCOVA) and the Kolmogorov-Smirnov test. The data were analyzed using the IBM SPSS Statistics v.20.0 program. Values of p <0.05 indicated statistical significance. Results: 72 cases presented a mean age of 57.9 years, predominantly female (60.6%) and patients older than 50 years (71.8%). There was an overall decrease in lumbar lordosis values in the immediate postoperative period, without major global changes in late evolution. It was found that patients with a pelvic incidence greater than or equal to 60° tended to have the other ES parameters elevated. Conclusion: There was no significant difference between the radiographic variables of the sagittal lumbopelvic balance in the evaluated periods. Lumbar lordosis and pelvic incidence were the main modifying factors. Improvement of low back pain after the THA, without changes in parameters, suggests different pathology mechanisms still to be clarified.

P170 - The Impact Of Obesity On Young Individuals Suffering From Lumbar Disc Herniation: A Retrospective Analysis Of 97 Cases

Sara Lener¹, Sebastian Hartmann¹, Claudius Thomé¹, Anja Tschugg¹

¹Department of Neurosurgery, Medical University of Innsbruck, Innsbruck - Austria

Background: Obesity is associated to the traits of modern Western affluent life, so that the prevalence might rise in the future decades, especially in young adults. Currently, 3.8 - 7.1% of young adults in middle Europe are obese and the literature provides evidence that there is an impact on spinal disease. Due to the lack of data regarding lumbar disc herniation, the purpose of this study was to detect the impact of obesity in young adults suffering from herniated lumbar disc . Methods: Ninety-seven patients aged between 17 and 25 years were included in this retrospective analysis. Patients were categorized into two groups according to their Body Mass Index, group obese (O, ≥ 30kg/m²) and group non-obese (NO, < 30 kg/m²). The data evaluation included patient’s characteristics, treatment details and treatment outcomes. Results: Group NO showed no significant differences in recovery from motor deficits (p = 0.067) or pain (p = 0.074) in comparison to group O. Obesity and smoking showed no differences in the occurrence of motor deficits at diagnosis (66.7% vs. 37.0%, p = 0.063) but showed a significant impact at the third postoperative day (50% vs. 17.3%, p = 0.015) and at discharge (41.7% vs. 14.8%, p = 0.025). After 6 weeks, no significant differences were detected. Conclusion: The negative impact of obesity and on the incidence, but not precisely on recovery, of lumbar disc herniation could be demonstrated for individuals aged 25 or younger, unless they were smokers. Even though outcome is comparable at 6 weeks follow up, long-term consequences have not been investigated. Therefore, prospective clinical trials will be mandatory.

P171 - Medium-Term Results Of Surgical Treatment Of Low-Grade Isthmic Spondylolisthesis Without Intervention In The Spinal Canal

Jan Stulik¹, Petr Nesnidal¹, Michal Barna¹

¹Department of Spinal Surgery, First Faculty of Medicine, Charles University and Teaching Hospital Motol, Prague - Czech Republic

Introduction: The vast majority of patients with ischemic low-grade spondylolisthesis is clinically asymptomatic. Failure of conservative procedures indicates surgical treatment. The basic pillar of surgical care is instrumented spondylodesis, with or without decompression. In our retrospective study of prospectively collected data, we present a group of 22 patients with low-grade isthmic spondylolisthesis treated primarily by posterior reduction and fusion of the affected segment without decompression of the spinal canal with subsequent anterior interbody fusion autografts. Material and Methods: We have used the mentioned techniques on 22 patients with complete documentation and a minimum interval of 3 years after surgery, from a total of 332 patients operated on at our department between 2009 and 2011 with the diagnosis of spondylolisthesis in the lumbosacral spine. Among them were 9 women and 13 men aged 15 to 58 years old with an average of 37.1 years. The patients were monitored in standard intervals. In our sample, we continuously evaluated Oswestry Disability Index (ODI), Visual Analog Scale for pain in the lumbar spine (VAS) and the development of neurological findings at a mean of 59.9 months. On imaging tests, I observed a shift in mm, the angle of the affected segment, disc height, bone fusion and stability of the operated segment. Results: VAS decreased from preoperative values of 6.7 to 1.8 in the control of at least 3 years, i.e. an improvement of 73.1%. For ODI preoperative value of 25.0 decreased to 7.4, the improvement in the value of ODI was 67.3%. I have not observed any emergence of new radicular symptoms. The shift value before the operation was 11.0 mm, then controls at 0.9, 1.5 mm and 3 years of 1.6 mm. The angle of the affected segment was 2.0°, then 12.0°, 9.1° and 3 years of 8.5°. Elevations disk was 9.0, below 13.8, 12.1 mm respectively after 3 years 11.5 mm. Clear fusion X-ray and possibly CT was seen in 20 patients (90.9%). Discussion and Conclusions: The therapeutic goal in symptomatic isthmic spondylolisthesis of a low degree is stabilization of the affected segment with the acquisition of bone intervertebral fusion. We found that the combined treatment of isthmic spondylolisthesis lumbosacral spine without the intervention of the spinal canal combines the benefits of both surgical techniques. It minimizes the risk of impairment of neural structures, and in particular the emergence of postoperative fibrosis.Clinical results and success of achieving bone fusion is comparable with other techniques.

Keywords: spondylolisthesis, surgical therapy, reduction, anterior lumbar intrerbody fusion, ALIF, transpedicular fixation, fusion

P172 - Implantation Of A Bone-Anchored Anular Closure Device Following Tubular Minimally Invasive Discectomy For Lumbar Disc Herniation

Geoffrey Lesage¹, Frederic Martens¹, Jonathan Stieber²

¹Department of Neurosurgery, OLV Hospital Aalst, Aalst - Belgium ²Spine Surgery, NYU School of Medicine, New York - United States

Introduction: Despite refinements in the technique for lumbar discectomy, there continues to exist a persistent incidence of recurrent disc herniation and postoperative disc degeneration leading to back pain. A novel bone-anchored anular closure device (ACD) has been developed to address these complications by permitting a minimal discectomy, while closing a large anular defect in order to maintain a maximal amount of disc tissue while preventing recurrent disc herniation. The purpose of this report is to explore the feasibility and safety of a new tubular minimally invasive technique for implantation of this type of ACD as an adjunct to microscopic lumbar discectomy. Material and Methods: The Barricaid ACD (Intrinsic Therapeutics, Inc.; Woburn, MA USA) was implanted in 57 patients after standard lumbar discectomy with limited nucleus removal utilizing a tubular minimally invasive approach (15 in a randomized controlled trial, and 42 in an observational cohort). Results: The ACD was implanted with a low rate of perioperative complications in a case series of 57 patients. In two patients, the ACDs could not be implanted and conventional tubular discectomy with limited nucleus removal was performed; an ACD was successfully replaced during insertion in another patient; and a fourth patient experienced an incidental durotomy without further clinical sequelae. Comparing the 15 patients implanted with an ACD within an RCT to 16 patients from the concurrent control group treated by the same surgeon, within two years of surgery the ACD patients experienced fewer reoperations (2 vs 5), fewer symptomatic reherniations (1 vs 3), and greater average improvement in VAS-leg (91% vs 77%), VAS-back (79% vs 58%), ODI (87% vs 74%), SF36-MCS (31% vs 18%), and SF36-PCS (72% vs 56%). Conclusion: Implantation of this novel, bone-anchored ACD can be safely and effectively performed though a minimally invasive tubular approach as an adjunct to standard lumbar discectomy in patients with large anular defects, permitting less removal of nucleus while potentially decreasing the rate of recurrent disc herniation. Clinical outcomes including pain, function, reherniation and reoperation appear to be improved over discectomy without implantation of the ACD, though further study is needed.

Diagnostics

P173 - Clinical Testing Of The Russian Version Srs-22 Questionnaire In Adult Scoliosis Patients

Oxana Prudnikova¹, Valentina Kamysheva²

¹Neurosurgery Department, Kurgan - Russian Federation ²International Department of Ilizarov Center, Kurgan - Russian Federation

Introduction: To evaluate clinical features of scoliosis signs in adult patients the Scoliosis Research Society (SRS) -22 questionnaire was designed and modificated. Implementation of adapted Russian version of questionnaire requires clinical testing. Materials and Methods: 196 adult scoliosis patients were administered the adapted Russian version SRS-22. Translation/retranslation of the English version of SRS-22 for Adult Scoliosis Patients was done. (Bridwell K.H., 2011). The results of adapted Russian version of SRS-22 were compared with Oswestry Diability Index (ODI) and pain scale. Cronbach’s α reliability index was used to measure internal consistency of a questionnaire. Variation statistics method was used: calculation of the arithmetic mean (M) and mean deviation ( ± m), Pearson correlation coefficient with evaluation according to Chaddock scale to evaluate consistency of mean differences we used Student t-test to determine statistical consistency index. Results and Discussion: Cronbach’s α reliability index inside domains in adult scoliosis patients was < 0.7 and demonstrated satisfactory internal consistency of adapted Russian version of SRS-22. Analyzing adapted Russian version of SRS-22, domain means (specific for deformities – function, self-image, mental health, satisfaction with treatment) were higher in patients with scoliosis that proves that adapted Russian version of SRS-22 is specifically for patients with spine deformities. High correlation coefficient was detected in domain function and ODI. Correlation of domain back pain and pain evaluation according to pain scale was moderate. Conclusion: This adapted Russian version of SRS-22 is reliable specific and effective instrument for self evaluation of health in adult scoliosis patients and can be used to test results after surgical treatment of this category of patients.

P174 - A Rare Case Report Of C1 Posterior Arch And C2 Laminar Hypertrophy Causing Cervical Myelopathy

Srinath P¹, Ravi V²

¹Department of Orthopedics, Apollo Hospitals, Chennai - India ²Department of Spine Surgery, Apollo Hospitals, Chennai - India

Introduction: Cervical stenosis as a cause of cervical myelopathy is a well recognized entity described mainly in the subaxial cervical spine but in upper cervical spine, it is quite rare which can be developmental or acquired. Hypertrophy of the posterior arch of atlas and axis in the absence of any ring hypoplasia as an isolated cause of cervical myelopathy has not been reported earlier. Material and Methods: A 52year old gentleman presented with complaints of neck pain following a fall 2months ago with pain radiating to both upper limbs (right>left) and paraesthesia in both upper limbs. There was no history of bowel or bladder dysfunction. Neurological examination revealed presence of reduced power on the right side (MRC grade 4+/5) with reduced sensation on right upper limb. Patient has a MODIFIED JOA SCORE of 11 with NURICK GRADE 3. CT scan revealed degenerative changes with an expanded hyperostotic posterior arch of C1 & C2 lamina. MRI showed constriction of the Dural sac with presence of possible posterior arch of C1 & C2 lamina lesion with myelopathy changes. During surgery there was an ossified ligamentumflavum. The posterior arch of the atlas and axis was hypertrophied. C2 spinous process was removed, C1 arch removed and C2 laminectomy done along with removal of ossified ligamentumflavum. Final histopathology of the lesion confirmed the diagnosis of hypertrophied posterior arch of atlas and lamina of axis. Results: The present case remains distinct as the antero-posterior diameter of the canal was decreased and there was an isolated presence of hypertrophied posterior arch of the atlas and lamina of axis leading to development of myelopathy. There was a history of trauma in the past, so injury with periosteal reaction and thickening/hypertrophy of the posterior arch appears to be the most plausible mechanism. Intact and smooth cortical margins of the expanded posterior arch as present in this case may be a feature indicating the presence of benign C1 posterior arch and C2 laminar hypertrophy. Conclusion: An unusual case of cervical myelopathy due to hypertrophied posterior arch with complete atlas ring and axis is reported which can be misdiagnosed as a neoplasm leading to redundant investigation and management dilemmas. Being aware of such an entity may avoid diagnostic surprises and facilitate patient prognostication and management.

P175 - Back Pain With Bladder/Bowel Dysfunction In A Child- Is This Cauda Equina Syndrome

Purnajyoti Banerjee¹, Azal Jalgaonkar¹

¹Department of Orthopaedics, Frimley Park Hospital, Camberley - United Kingdom

Introduction: Cauda equina syndrome (CES) represents acute compression of the lower spinal nerves. They present with a diverse array of symptoms and signs including back pain, perianal paraesthesia, urinary of faecal retention or incontinence with loss of perianal sensation and tone. If the diagnosis is missed, permanent nerve damage leads to lifelong faecal, urinary and sexual dysfunction. Magnetic resonance imaging (MRI) is the investigation of choice in CES and urgent surgical decompression is indicated. It is perceived that CES is rare and even more so amongst children. Incidence of CES amongst children has not been assessed yet. Objective: To estimate the yield of true positive cases detected with MRI scans amongst children aged 0-15 years. Material and Methods: We retrospectively reviewed all children who were referred to a district general hospital (DGH) as potential CES and their MRI scan outcome. Data was obtained from the case notes and final MRI scan report. Results: Between August 2012-July2017, 295 MRI scans of lumbar spine were undertaken in children (0-15 years). Fifteen (5.1%) cases were referred with symptoms and signs suggestive of CES including back pain with bilateral sciatica and bowel/bladder dysfunction. The mean age was 10.4 (SD3.6) years with M: F = 5:10. None of these patients had positive MRI scan with Cauda Equna compression. Furthermore, 14 children (4.7%) were found to have disc prolapse. The mean age was 13.3 (SD3.3) years and M: F = 4:10. None of them presented with features of CES. Their main complaint was acute or chronic back pain with unilateral leg pain. None of these cases were operated for CES. Conclusions: Our results reflect the rarity of CES amongst children. This paper suggests that it is unlikely for children to have Cauda Equina compression although rare case reports are documented. We also report the occurrence of disc pathology in children that is uncommon but not rare. We therefore recommend that children with back pain and sciatica should undergo routine MRI to exclude disc pathology. However, a consultant should evaluate children with features of CES before the decision for an urgent scan is recommended.

P176 - Radiological Fusion Criteria Of Postoperative Anterior Cervical Discectomy And Fusion - Systematic Review

Masahito Oshina¹

¹Department of Orthopedics, The University Tokyo Hospital - Japan

Introduction: A number of methods have been used to diagnose pseudarthrosis after anterior cervical fusion. However, in practice, making an accurate diagnosis can be quite challenging. There may be disagreement between the surgeon and independent reviewers. The diagnosis often depends on the surgeon’s subjective assessment because universally accepted radiographic criteria do not exist. Surgical re-exploration may be the most reliable method, but is impractical and even in symptomatic patients, it is ideal to make a diagnosis prior to re-operation. Therefore, reliable diagnostic criteria for radiographic evaluation are important. Currently, some criteria for assessing fusion have been compared in literature, but there is no information on which method of evaluation of cervical fusion is the most commonly used or which criteria are the most reliable. The purpose of this study was to investigate criteria for assessing fusion after anterior cervical spine surgery based on the literature. Material and Methods: We conducted MEDLINE and SCOPUS database searches for English-language articles published from January 1, 2011 to June 30, 2016, for articles on anterior cervical fusion describing assessment for fusion. We extracted data from 59 articles, including the timing of follow up, graft construction, radiographic modality, and radiographic criteria for assessing fusion. We categorized every described method for assessing anterior cervical fusion and then performed a cross-sectional review. Results: Fifty-nine articles were reviewed. Eleven types of fusion were mentioned. The four most common were presence of bridging trabecular bone between the endplates (43 articles), absence of a radiolucent gap between the graft and endplate (30 articles), absence of or minimal motion between vertebral bodies on flexion-extension radiographs (24 articles), and absence of or minimal motion between the spinous processes on flexion-extension radiographs (11 articles).For the two most common measures, computed tomography (CT) was sometimes required, as plain radiographs were insufficient to demonstrate bridging bone or radiolucent gaps clearly. However, determining those findings on imaging is subjective. Of the 11 articles exploring the motion between the spinous processes, six stated that there must be 0 mm difference between the spinous processes on flexion-extension radiographs. But complete consistency with this strict standard would be difficult without using a standardized coordinate system for radiography. Three articles used a maximum value of 2 mm. Conversely, a previous reliable study reported that 1 mm on CT was reasonable and had good specificity and positive predictive value. Conclusion: The most common fusion criterion for determining fusion was bridging trabecular bone between the endplates. The 0-mm criterion to demonstrate no motion of spinous processes on dynamic radiography is too strict. We recommend a maximum difference of 1 mm between the motion of spinous processes on extension and flexion to confirm fusion.

P177 - Severe osteoSphytosis of the antSerior cerSvical sSpine should not be Established as the Primary Cause of Dysphagia unless a Spect-ct Scan has ruled out Dysphagia Lusoria. A Case Report

Grigorios Delaportas¹, Georgios Manolarakis²

¹Department of Orhtopaedics, University of Vermont Medical Center, South Burlington - United States ²Dept. of Orthopaedics, Sitia’s Health Center – General Hospital, Sitia, Crete, Greece, Heralkeion - Greece

Introduction: Dysphagia lusoria is caused by a rare extrinsic congenital vascular lesion (aberrant/retroesophageal) of the right subclavian artery that presses the esophagus and making difficult the swallowing of solid food and through the time-course it may involve liquids as well. Its incidence lies between 0.4% & 2.3%. This case-report highlights dysphagia lusoria as a significant cause of difficult and/or painful swallowing especially in cases in which conventional work-out fails to establish the right diagnosis. Material and Methods: This case refers to a 58-year old woman who presented to our clinic with pain in the posterior and anterior aspects of her lower cervical spine that had been persisting over the last 6 months. Symptoms were aggravated with rotation of her neck to the right and left, extension of the neck, and swallowing of solid foods. Conventional radiographs of the cervical spine revealed mild degenerative changes at C5-C6/C6-C7 including minor osteophytosis in the anterior superior and inferior aspects of the same vertebrae. Recent blood tests had ruled out thyroid disease. Results: Guided by the conventional radiograph findings, trigger point injections were ordered in order to address the pain in the posterior neck; the patient was also referred for a series of exams including upper endoscopy (EGD), esophageal manometry, and barium esophagogram to address dysphagia. Trigger point injections achieved neck analgesia at 50% for a week, but had no effect on dysphagia. Having already ruled out peripheral nerve root entrapment and given negative EGD, esophageal manometry, and barium esophagogram, in a final attempt to investigate possible facet arthropathy and/or disc disease and especially esophageal tumor, we followed up with SPECT-CT scan, which revealed an aberrant right subclavian artery, the cause of dysphagia lusoria. Conclusion: Dysphagia lusoria should be ruled out even in the presence of severe osteophytosis that warrants a surgical intervention. The decision of surgical intervention should definitely be reinforced by a SPECT-CT scan even in the presence of negative barium swallowing test or EGD as SPECT-CT provides detailed anatomical as well as functional information through merged images; thus, it can assist in the implementation of the proper therapy.

P178 - A Clinical Correlation Research Of Hoffmann Sign And Imaging Findings In Cervical Myelopathy

Yuqiang Wang¹, Jing Cao¹, Yilin Liu¹, Weidong Wang¹, Min Zhang¹, Min Zhang¹, Hao Yang¹, Limin Wang¹

¹The First Affiliated Hospital of Zhengzhou University, Zhengzhou - China

Introduction: The Hoffmann sign is initially proposed by Johann Hoffmann at the end of the 19th century. Currently, a standard neurological examination is routinely included the Hoffman sign. Hoffmann sign is used as an indicative of cortico-spinal pathway dysfunction and upper motor neuron lesion. A positive Hoffmann sign, and especially was accompanied by other reflex abnormalities that could indicate upper motor neuron lesions, strongly suggests a potential diagnosis of cervical spinal cord compression. In the general population, the overall incidence of a positive Hoffmann sign is reported about 0.7%-3%. The clinical usefulness of Hoffmann sign remains controversial in previous reports. The goal of this study was to research sensitivity, specificity, positive predictive values and negative predictive values of Hoffmann sign in cervical myelopathy, then investigate the relationship between Hoffmann sign and cervical myelopathy. Material and Methods: During March 2015 and February 2016, total of 107 patients with symptoms of cervical myelopathy, whose clinical signs and imaging datas were recorded, were treated. The data included MRI imaging, complete medical history, physical examination record including Hoffmann sign, age, sex, height, weight, and systemic disease. All patients were grouped according to the performance of Hoffmann sign (positive as group A and negative as group B). Vertebral canal sagittal diameter (a) and vertebral sagittal diameter (b) were measured on cervical lateral X-Ray. Ratio of a and b (Ra/b) was calculated on cervical 3 to 7. Largest sagittal diameter herniated disc (AB) and vertebral canal sagittal diameter (CD) were measured on cross-section of MRI. Ratio of AB and CD (SI) was calculated on cervical 3 to 7. Retrospective analysis all the datas to assess specificity, sensitivity, positive and negative predictive values of Hoffmann sign for cervical cord lesions. Results: There were 56 patients in group A and 51 patients in group B who met our inclusion criteria. In group A, 17 were female (30.4%) and thirty-nine were male (69.6%). The average age was 53 years old. In group B, 18 were female (35.3%) and 33 were male (64.7%). There was no significant difference in the age, BMI, gender between two groups. 53 (94.6%) showed severe cervical cord compression and/or myelomalacia in group A. While thirty-three (64.7%) of them had severe cervical cord compression and/or myelomalacia in group B. Hoffmann sign was found to have 61.6% sensitivity, 85.7% specificity, 94.6% positive predictive value, and 35.3% negative predictive value for cervical cord compression. There were statistically significant in Ra/b on cervical 4 to 7 between two groups (P<0.05). However, there was no significant difference in Ra/b on cervical 3 (P>0.05). There was no significant difference in SI between two groups (P>0.05). Conclusion: Hoffmann sign can not be relied upon as a stand-alone physical examination finding for predicting the presence of cervical spinal cord compression. If a patient presented with a positive Hoffmann sign, we should pay high attention to the possibility of the diagnosis of cervical myelopathy. Cervical MRI imaging should be advised for the patient with Hoffmann sign. Degenerative cervical stenosis has correlation with positive Hoffmann sign. While, degree of spinal cord compression has no effect on performance of Hoffmann sign.

P179 - Direct Nerve Root Stimulation: A Novel Approach To Neuromonitoring For Reduction Of High Grade Spondylolisthesis

Christopher J. Nielsen¹, Stephen J. Lewis¹, Samuel Stranzas¹, Laura Holmes¹, Maheswara R. Akula¹

¹University of Toronto, Toronto - Canada

Introduction: Traditional methods of neuromonitoring for spinal deformity cases lack accuracy and reproducibility in monitoring for high grade spondylolisthesis. Free run electromyography (EMG) has not been shown to be accurate in detecting radicular injuries in lumbar degenerative surgeries. The purpose of this project is to introduce direct nerve stimulation as a novel alternative to nerve root monitoring in the reduction of high grade spondylolisthesis. Materials and Methods: Prospectively collected intra-operative neuromonitoring data including MEP, SSEP, and free run EMG, was collected on pediatric patients undergoing posterior reductions for high grade L5/S1 spondylolisthesis. A fourth modality using direct nerve root stimulation (DNS) of the L5 and S1 nerve roots was recorded by placing a stimulator directly on the exposed nerve root and recording threshold stimulus. Along with the other modalities, DNS was carried out prior to reduction, following all reduction maneuvers and prior to closure. Results: 5 patients with high grade spondylolisthesis were analyzed, 4 with Grade IV and 1 with Grade V. All patients had positive bilateral straight leg raises. 4 of 5 patients had intact pre-operative lower extremity motor examinations, with 1 patient having left-sided 4/5 EHL weakness. 3 patients did not have any neuromonitoring alerts during their surgical procedure. Their average change in threshold value from baseline to final stimulation in these cases for the L5 nerve root was 1.3 mA. 2 patients had intraoperative alerts of MEPs, SSEPs and EMGs which resulted in greater nerve root stimulation threshold values at closing compared to baseline. One patient showed a 3-fold increase in DNS threshold while a second patient had a 25-30-fold increase. In both cases, further nerve root exploration and decompression was performed. Both cases resulted in immediate post-operative neurologic deficits in bilateral ankle dorsiflexion. Conclusion: After establishing a pre-reduction threshold of direct nerve stimulation, increases in DNS threshold were associated with post-operative neurologic deficits in cases of posterior reduction of high grade spondylolisthesis. DNS provided an accurate measure of nerve function in this series. Recognizing increases in DNS thresholds intraoperatively can alert the surgeon to potential real time nerve injuries. A larger multicenter series can help determine the utility of this technique.

P180 - Managing Acute Back Pain Without Trauma- An Evidence Based Approach To The Algorithm And Systematic Review Of The Literature

Carolin Melcher¹, Bernd Wegener¹, Alexander Paulus¹, Wolf Mutschler², Volkmar Jansson¹, Karl Georg Kanz³, Christof Birkenmaier¹

¹Department of Orthopedic Surgery, Physical Medicine and Rehabilitation, University Hospital LMU Munich, Munich - Germany ²Department of Hand-, Plastic- and Trauma Surgery, Ludwig-Maximilians-University (LMU), Munich - Germany ³Department of Trauma Surgery, Emergency Department, Klinikum rechts der Isar, TU Munich, Munich - Germany

Introduction: Low back pain is one of the most prevalent health care issues in the developed nations and imposes a considerable social and economic burden. Over the last 15 years most countries published guidelines to help primary health care providers, outpatient clinics or A&E departments, especially with evaluation and treatment of patients presenting with low back pain. Unfortunately, only few of these guidelines provide applicable decision pathways and most lack easy and accessible operating sequences. Therefore, an algorithm was originated and has now been evaluated to demonstrate quality and effectiveness within the means of evidence-based medicine. Methods: To employ the principles of evidence-based medicine, the clinical literature was searched to answer the specific clinical questions in the algorithm and to evaluate the targeted red flags. The studies identified in the search were then rated based as to their scientific merit using levels of evidence. Finally, the answers to the clinical questions were reformulated as recommendations to which grades of strength were assigned based on the best clinical evidence available at the time. Clinical guidelines were searched using electronic databases for the period of 2000–2017. To cover Europe, North America and Asia-Pacific, guidelines from Germany, Norway, Belgium, Italy, the UK, the US, Canada, Australia and New Zealand were selected. Furthermore, the content and reference list of relevant reviews on the guidelines was scanned and papers were included in the progress once they matched the criteria. Results: The five checklists for red flags and eleven clinical questions of the algorithm were addressed and evaluated with regards to the included guidelines. Furthermore, recommended diagnostic tools and treatment options were assessed and compared. The respective recommendations were graded by strength of the supporting literature, which was stratified by levels of evidence. All clinical questions were addressed in at least one guideline as well as most of the redflags. Only in question of a possible life-threatening condition most guidelines didn't commit or stayed very vague. These items were then supported by at least 2 papers each. Altogether the recommendations of the included guidelines are mostly concurrent even though there are still some significant differences. Conclusion: Overall the algorithm meets the requirements of evidence-based medicine and best available evidence and thus is an effective and accurate tool to aid practitioners in the care of patients with acute back pain. The lack of information regarding some questions might be explained by the targeted audience of the guidelines or differences in the set-up of medical care.

P181 - Calcific Tendinitis Of The Longus Colli Muscle: A Neglected Cause Of Acute Cervical Pain

Alvaro Silva¹, Ratko Yurac¹, M. Francesca Castoldi¹, Juan José Zamorano¹, Bartolome Marré¹, Benjamin Guiloff¹, Guillermo Izquierdo¹, Matías Delgado¹, Carolina Avilés¹, Camila De la Barra¹

¹Clinica Alemana - UDD, Santiago - Chile

Introduction: Calcific tendinitis of the longus colli muscle (CTLCM) is an inflammatory response to an abnormal hydroxiapatite crystals deposit in the superior oblique tendon of the longus colli muscle. It is a very infrequent disease; 0.5 per 100.000 people/year, generally not listed as a differential diagnosis of cervical pain. Computed tomography (CT) or magnetic resonance imaging (MRI) are the gold standard radiological exams to certify this diagnosis. The aim of this study is to present our diagnostic pathway and treatment of these patients. Materials and Methods: We performed a query in our institution’s radiological database, searching for the term “longus colli”, from January 2010 to December 2015, identifying three patients with CTLCM. The medical records and imaging of each patient was reviewed. Results: Three patients with image-confirmed CTLCM, two female and one male. They all consulted for neck pain in the emergency room. The first differential diagnosis did not include CTLCM and the mean time from consultation to final diagnosis was six days in average. All three cases were radiologically diagnosed with CT scan or MRI. Only one patient required hospitalization for pain management, but in general, the management of all the patients was similar and included non steroidal anti inflammatory drugs (NSAIDs), acetaminophen, a cervical brace and physical therapy. Conclusion: Differential diagnosis for acute cervical pain does not include CTLCM on a regular basis. None of the physicians who assessed these patients initially considered CTLCM as a possible cause for their neck pain. The clinical manifestations were later radiologically explained. It is important to add this diagnosis to our list of differentials for acute neck pain, in order to achieve a timely diagnosis and treatment. It is highly likely that the incidence of CTLCM is actually greater than what we think, especially because it is a self-limited disease that usually resolves by itself not needing further diagnostic measures. Odynophagia, dysphagia, or fever are common associated symptoms, but are not the most common findings. In such cases, infectious pathologies must be ruled out with proper imaging. Typical CT scan findings include prevertebral soft-tissue swelling and amorphous calcification anterior to C1-C6. To help rule out other differential diagnoses, there should be absence of rim-enhancing collection in the retropharyngeal space, as well as no suppurative retropharyngeal lymphadenopathy. Optimal treatment can be given to these patients and other invasive tests can be avoided with a high clinical suspicion and in the absence of other alarm symptoms such as fever or dysphagia.

P182 -The Role F18 Bone Scan In Evaluation Of Low Back Pain Mainly In Subclinical Facetal Dysfunction

Pankaj Sharma¹, Alok Ranjan¹

¹Department of Neurosurgery, Apollo Hospital, Hyderabad - India

Degeneration of spine is a prevalent problem seen in elderly population. It is an inevitable consequence of aging. Miller et al study on 600 autopsy specimens reported increase in disc degeneration from 16% at age 20 to approximate 98% at age of 70 years. It has been linked to low back pain, but still exact relationship between two is not clear. The majority of published clinical investigations report no correlation between the clinical symptoms of LBP and degenerative spinal changes observed on radiologic imaging studies, including radiographs, computed tomography (CT), magnetic resonance imaging (MRI), and radionuclide bone scanning. The association between degenerative changes in the lumbar spine facet joints and symptomatic LBP remains unclear and a subject of on going debate. . Most commonly these investigations reveals mixed features of degenerative disc disease, modic changes occurring at the level of vertebral body, canal stenosis with ligamental hypertrophy or facetal hypertrophy with or without slippage, medialized facet joints, in various combinations. During the process of degeneration facetal arthritis is a feature of early instability. Role of 18 F PET CT in evaluation of facet and disc abnormalities in patient with low back pain was studied by El Maghraby and colleagues. There are not many studies further on 18 F PET CT in back pain. We did this study is to find the use of F18 scan in evaluation of outdoor/ indoor patients with low back pain, mainly in subclinical facetal dysfunction for surgical intervention.

Methodology: Investigations like dynamic X-ray of lumbar spine, MRI lumbar spine were done as required. F18 bone scan was done for the patients who presented with predominant back pain, leg pain or neurogenic claudication as primary complaint, and X-ray and MRI are not showing any obvious underlying cause. Test was done in fasting state. ¹⁸F – NaF was injected and whole body PET scan was done on a Siemens Biograph PET-CT scanner. Doses were calculated by the physicist as per BMI and standard guidelines. Scan was reviewed and reported by senior nuclear medicine consultant. Results: In study a total of 160 patients were evaluated. The F18 bone scan showed abnormal foci of uptake in the spine in 120 patients (75%). 74 cases (61.67%) showed uptake suggestive of degenerative disc diseases, Isolated uptake at facet joint suggesting facet joint arthritis were seen in 14.16% (17 cases). About 24.1% of the patients with back pain showed uptake pattern suggesting both facet joint arthritis and degenerative disc disease (29/120). Multiple level changes were seen in 37 patients (30.08%).Distribution of changes seen as per spinal levels are shown in graph 5. Our study was done prospectively and patients were selected from outdoor. About 137 patients (85.6%) with back pain had no previous operative procedures in the spine. There were about 23 patients (14.4%) with failed back surgery (FBS). The F18 bone scan showed high sensitivity of uptake in 78.3% patients of FBS. Global outcome score of the patients under subgroup of facetal changes (isolated facetal arthritis + facetal arthritis with degenerative changes).Surgical interventions were fusion with implants, decompression, facetal block, RF lesioning, epidural steroid injection. Total no. of patients in this subgroup which underwent intervention were 20, and 80% patients had good global outcome during follow up, while 26 patients received medications and physiotherapy, only 38.46% patients had good global outcome. Conclusion: The F18 Bone Scan has a potential use in evaluating patients with back pain. This study shows the potential efficacy of F18 Bone Scan in diagnosing facet joint arthritis and degenerative disc diseases in adult patients who present with back pain. Role of F18 bone scan was not studied previously in relation with treatment planning. We noticed a significant better outcome in a group of patients where F18 findings for facet arthritis helped in deciding surgical intervention. It also showed tracer uptake in 78.3% of failed back patients who are having persistent pain and found to have facet joint arthritis and/or degenerative disc disease.We conclude that F18 Bone Scan has a promising role in identifying causes of persistent back pain and treatment recommendation for facet arthritis. Further large scale studies are recommended to establish the clinical significance of F18 Bone scan in assessing the wide spectrum pathologies for back pain and to explore its further potential in identifying patients who will benefit from surgery.

P183 - Responding To Intra-Operative Neuromonitoring Alerts In Spinal Deformity Surgery: A Pilot Data Form Can Summarize Key Intra-Operative Data

Stephen Lewis¹, Maheswara Akula¹, Christopher J. Nielsen¹, Samuel Strantzas¹, Laura Holmes¹, Lawrence G. Lenke¹, Niccole Germscheid¹, Marinus de Kleuver¹

¹Department of Orthopaedics, Sickkids Hospital - Canada

Introduction: Controversy exists in monitoring and interpreting intraoperative neurophysiological data. Significant debate remains in determining which changes are significant and what actions, if any, are required in response to intra-operative changes. The purpose of this study was to develop a data collection form to prospectively collect intra-operative neuromonitoring and operative data, to capture the timing of alerts and correlate them with surgical and nonsurgical manoeuvres performed in response to these changes. The effectiveness and utility of the form was analysed and will serve as a pilot to a larger multicentre project with the goal to develop a care pathway in the use of intra-operative neuromonitoring for spinal deformity surgery. Material and Methods: Pediatric patients undergoing cord level spinal deformity surgery were consecutively enrolled. Detailed intraoperative real time neuro monitoring data was prospectively collected on the data sheets providing the specific information related to patient characteristics, radiological parameters, timing and actions performed in response. Results were analysed using appropriate statistical methods. Patients were divided into two groups based on presence or absence of significant alerts which were defined as > 50% loss of MEP or SSEP amplitude relative to baseline. Results: Over 6 months, 54 consecutive patients in a single centre underwent cord level spinal deformity corrective surgery. 17 significant intra-operative alerts occurred in 12 patients. The alert group consisted of 9 idiopathic scoliosis, 2 neuromuscular and one syndromic. The mean age of the alert group was 15.0 ± 2.3 years with a mean Cobb of 87°, compared with 14.2 ± 3.1 and 77° in the non-alert group (p > 0.5). 92% of alerts were MEP and 8% SSEP. 30% of alerts were blood pressure related, 28% occurred during osteotomies, 23% during reduction manoeuvres and 19% related to traction and positioning. Measures taken to revert the alerts included correcting hypotension, adjusting anaesthesia, pausing surgery, reducing the reduction, temporarily removing the rods and decreasing the traction. Multiple actions were employed in 10 alerts. 9 MEP alerts were bilateral and 7 unilateral, of which 3 were associated with SSEP changes. Seven bilateral MEP alerts recovered completely, with the time to resolution in 2 cases of > 60 minutes, 20 - 60 minutes in 2, and < 20 minutes in 3 cases. Two MEP alerts did not recover to baseline: one to 25% and the other to 75% of baseline by the end of surgery. Of the 7 unilateral alerts, 2 recovered completely in < 10 minutes, 4 cases recovered to 75% of baseline in < 20 minutes, and one recovered to 25% of baseline at closure. There were no post-operative neurological deficits. Conclusions: The real-time intraoperative information provided the necessary information to direct key surgical decisions. After the systemic causes, reduction measures and osteotomies were the leading causes for MEP alerts. Responding to these alerts reversed the MEP changes, potentially preventing permanent neurological damage. The data form provided an excellent summary of each case and can serve as a basis for a large scale randomised prospective study for development of a clinical care pathway.

P184 - The Usefulness Of Icg Videoangiography In The Cervical Spine Surgery To Evaluate The Patency Of Va

Jong beom Lee¹, Jae Taek Hong¹, Il Sup Kim¹, Jung Jae Lee¹, Jaehoon Sung¹, Seung-Ho Yang¹, Chul Bum Cho¹

¹Catholic University Vincent Hospital, Suwon - Korea

Introduction: Indocyanine green (ICG) videoangiography is a new technique that allows for real-time evaluation of blood flow in the aneurysm and vessels. Intra-operative indocyanine green (ICG) videoangiography is a useful addition to cerebrovascular neurosurgery. We evaluate the usefulness and limitation of ICG videoangiography during the cervical posterior fixation to evaluate the patency of the vertebral artery in the cases with high risk of VA injury. Material and Methods: Twenty-three patients (15 female, 8 male; mean age, 54.4 years) were evaluated. Near infrared ICG angiography was applied after the posterior screw fixation in the cases of high riding VA at the level of C2 vertebra, V3 segment anomaly and the situation of the VA injury was suspected during the surgical procedure. Results: ICG videoangiography is useful in different types of upper cervical posterior surgery. This technique is useful to evaluate the VA patency after screw instrumentation especially in the cases of the VA anomaly and high riding VA. And it is useful to identify the vessel patency after the inevitable VA management during the procedure. Overall, the procedure interrupted the surgical procedure for less than 5 minutes. One case of adverse skin reaction to the dye was encountered due to the dye leakage outside the vessel during the injection. ICG videoangiography has some limitations such as its inability to be viewed outside of the observed plane of illumination with infrared light and inconsistent complete washout, making repeated viewing sometimes difficult in structures surrounded by thick and excessive tissue. Quantitative evaluation of vessel flow is not possible with ICG videoangiography. Conclusion: ICG angiography could be a simple intraoperative evaluating tool with which the patency of the extracranial vertebral artery can be assessed. Compared with digital subtraction angiography, ICG angiography requires less time, personnel, and equipment, is safer, and can resolve smaller vessels, but is limited by the surgeon’s viewing angle and the depth of penetration of the infrared light. Even though it is necessary to expose the VA above the C1 arch or lateral to the C1 lateral mass to identify the ICG flow in the cases of CVJ surgery, it can be a useful tool to verify the patency of the possibly damaged VA during the screw placement. Unlike ultrasound technology, this technique is a hands-off method that can inform the surgeon about the flow patency of the extracranial vertebral artery.

P185 - Significance Of Dynamic Mri For The Surgical Decision Making Of Cervical Myelopathy

Jong beom Lee¹, Jae Taek Hong¹, Il sup Kim¹, Jung Jae Lee¹, Jaehoon Sung¹, Seung-Ho Yang¹, Chul Bum Cho¹

¹Catholic University Vincent Hospital, Suwon - Korea

Introduction: MRI study is very important to diagnose cervical myelopathy. And several reasons affect to these pathologic signs. Usually we examine only neutral position cervical MRI. But cervical motion is very active so many pathologic findings are shown dynamic features. The aim of our study was to decide to analyze significance of dynamic MRI for cervical myelopathy. Especially about OPLL and CMS group. Material and Methods: Patients with cervical myelopathy (n = 106) who underwent dynamic MRI were included in this study. We performed a retrospective analysis of surveillance data collected between Feb. 2014 and April 2017, 106 patients who had a spondylotic myelopathy at our institution. We measured diameter of the spinal canal and thickness of the ligamentum flavum (LF) at sagittal T2-weighted sequence. Evaluation of spinal stenosis at the neutral position, extension and flexion using grading system, Muhle’s classification. And we made two kinds of groups, cervical spondylotic myelopathy (CSM) and ossification of longitudinal ligament (OPLL). Than the measurements of the cervical spine in flexion, neutrality and extension were compared between CMS and OPLL. Results: Total 84 patients were included. 22 of 106 patients were excluded. 1 patient diagnosed to tumor. 7 patients diagnosed to instability. 4 patients diagnosed to traumatic instability. 9 patients were excluded due to absence of neutral image. Diameter of the spinal canal of the extension position was tended to become more narrowing than neutral position. Especially, diameters of spinal canal on C3-4, 4-5, 5-6 were more difference. The differences of diameter on C3-4, 4-5, 5-6 were 7.90 / 6.84, 7.23 / 5.88, 7.03 / 5.96 (neutral position /extension). And these values were about CSM group. And 360 levels on CSM group, about 25% were changed Muhle’s classification. The change of Muhle’s classification is significantly meaningful on CSM group. The differences of Muhle’s classification was 1.72 / 0.98 (CSM / OPLL). Conclusion: Extension image of dynamic MRI could be more effective in CSM cases rather than OPLL cases.

Disc Degeneration

P186 - The Role Of Bacteriological Factor In Etiology Of Degenerative-Dystrophic Diseases Of The Spine

Oxana Prudnikova¹, Zinaida Naumenko², Nikolay Migalkin²

¹Neurosurgery Department, Kurgan - Russian Federation ²Morphological Department, Kurgan - Russian Federation

Introduction: The role of infection in degeneration of intervertebral disks was studied to identify markers of inflammatory changes and determine tactics of treatment and prevention of postoperative complications. Objective: To review frequency and types of microbes causing infected intervertebral disks in degenerative spine conditions, comparing with clinical, pathohistological, radiological and MRI findings in order to determine tactical approaches to surgical spine interventions. Material and Methods: The study included 97 patients who underwent surgical treatment for degenerative spine conditions. Discectomy was performed for 46 patients, and uni-level decompression-stabilizing procedures produced for 51 patients. Microbiological (117 specimen) and pathohistological (73 samples) examination of excised disks, clinical and neurological assessment of patients were conducted with radiological and MRI findings evaluated. Results and Discussion: Based on bacteriological findings the patients were divided into two groups, the first including negative culture of intervertebral disk, and the second group showing pathogen growth. Lumbar spine at the level of L4-5 and L5-S1 vertebrae was the most common site of surgical intervention and pathogen examination. The incidence of infected disks was 25.6%. Positive culture of the disk specimen was observed in 27% of discectomy, and in 30.6% of decompression-stabilizing procedures. Most common pathogens were obligate anaerobic gram-positive bacteria (Propionibacterium acne) detected in 42.8% of the cases and epidermal staphylococcus (Staphylococcus epidermidis) observed in 31.4% of the cases. Mixed microflora was revealed in 20% of the cases. Pathohistological examination showed signs of chronic inflammation in 42.8% of patients with infected disk, no infection was observed in 5.7% of the cases. No statistically significant correlations were detected between the infected intervertebral disk and chronic disease, clinical manifestations, presence of sequester, Modic I type changes in MRI scan, unstable segment and changes in CT scan. Conclusion: A chance of infected disk was likely to be higher with repeated operative interventions and degenerative disks, tenderness and radicular syndrome. The theory of bacterial biofilm was shown to be the most statistically reliable mechanism of infected intervertebral disks. Further research are needed to study not only intervertebral disks but also ligamentum flavum, paravertebral muscles, bone vertebral tissue and the skin.

P187 - Early Readmission And Delayed Discharge Analysis From A Multicenter, Prospective, Randomized Study Of Discectomy With And Without Bone-Anchored Anular Closure: The German Experience

Senol Jadik¹, Adisa Kursumovic², Peter Douglas Klassen³

¹Department of Neurosurgery, University Clinic of SH, Kiel - Germany ²Department of Neurosurgery, Klinikum Deggendorf, Deggendorf - Germany ³Department of Neurosurgery, Bonifatius Hostpital Lingen, Lingen - Germany

Introduction: Readmissions and reoperations within the first few months of surgery are major factors driving negative clinical and financial outcomes. Providers are increasingly being asked to bear the financial burden of hospital admissions that occur within a certain time period after the index surgery, typically 30-90 days. Reherniation and progressive degeneration with are the main causes of poor outcome after lumbar discectomy and may necessitate early readmission and reoperation. An anular closure device (ACD) has been developed to address these causes, and a multicenter, prospective, post-market randomized clinical trial (RCT) is ongoing. This report evaluates the early safety of discectomy augmented with a bone-anchored ACD (treatment group) compared with discectomy alone (control group) at German centers in terms of delayed discharge and hospital readmission within the first 30, 60 and 90 days after surgery. Materials and Methods: The study population for this interim analysis consisted of all enrolled patients at German centers (10/21 sites) with 243/554 (115/278 control, 128/276 treatment) from an ongoing RCT to demonstrate superiority of discectomy with anular closure relative to discectomy alone. Key inclusion criteria include 6 weeks of failed conservative treatment, posterior disc height of ≥ 5 mm, minimum defect width and height, and baseline Oswestry and visual analog scale leg pain scores ≥ 40/100. Key exclusion criteria include prior surgery at the index level. This report, which comports with the study statistical analysis plan, presents safety and early readmission results within the first 30, 60 and 90 days after surgery by examining serious adverse events that were reviewed by a data safety monitoring board. Results: Implanted patients in the treatment group had significant lower incidences of readmissions or delayed discharges that were device or procedure related and index-level reoperations, compared with the control group. Conclusions: Discectomy augmented with bone-anchored anular closure has a similar safety profile compared with discectomy alone, with similar adverse event rates and minimal device-related complications reported. Furthermore, anular closure was associated with substantially lower rates of reoperations and early readmissions or delayed discharges, compared to discectomy alone. These results suggest that bone-anchored anular closure could play an important role in reducing short-term clinical and financial burdens following lumbar discectomy.

		30 days		60 days		90 days
		Treatment	Control	Treatment	Control	Treatment	Control
Readmission/ delayed discharge AE	All	5.5%	10.4%	8.6%	12.2%	10.2%	15.7%
	Related to device/ procedure	0.8%**	7.8%	0.8%**	9.6%	0.8%*	11.3%
Index-level reoperations		0.8%*	5.2%	1.6%*	7.8%	1.6%*	7.8%

* Trend for lower incidence Treatment vs. Control (0.05<p<0.10)

** Significantly lower incidence Treatment vs. Control (p<0.05)

P188 - Use Of Autologous Mesenchimal Stem Cells In Vertebral Arthrodesis In Lumbar Degenerative Disc Desease: Clinical Trial

David Pescador¹, Tony Setiobudy², Carlos Marqués¹, Fermín Sánchez-Guijo³, Sandra Muntion³, Lourdes Ollero⁴, Juan Francisco Blanco¹

¹Spine Unit, Department of Orthopaedics, Complejo Asistencial Universitario de Salamanca, Salamanca - Spain ²Spine Unit, Department of Orthopaedics, Mount Elizabeth Medical Centre, - Singapore ³Department of Hematology, Complejo Asistencial de Salamanca, Salamanca - Spain ⁴Department of Orthopaedics, Salamanca, Salamanca - Spain

Introduction: Lumbar degenerative disc disease (DDD) is a progressive and irreversible process that produces lumbar or radicular pain and causes disability. The established treatments are palliative measures, being the “gold standard” the posterolateral vertebral arthrodesis combined with autogenous bone. This technique involves the use of grafts which often cause morbidity. On the other hand, the study of cellular therapy has increased in recent years due to the potential of MSCs to differentiate into various cell lines. One of these cellular lines has to do with bone regeneration. The purpose of this study was to analyze the safety, feasibility and clinical efficacy of the implantation of autologous mesenchymal stem cells (MSCs) as a therapeutic alternative to the usage of autologous bone in patients with lumbar degenerative disc disease during the posterolateral fixation process. Material and Methods: A prospective clinical trial composed of phase I / II including 14 patients (>30 years old and <65 years old). All patients suffered from mono- segmental lumbar degenerative disc disease at L4-L5 or L5-S1 verified by Rx and nuclear magnetic resonance (NMR) and they have not responded to conservative treatment. From all patients’ bone marrow (BM), MSCs have been obtained and implanted during spinal fixation surgery through a tri-calcium phosphate carrier. Monitoring of patients includes a postoperative period of 12 months with 4 visits (after the first month, third month, sixth month and a year). In these visits, the clinical and radiological efficacy has been assessed by implementing the pain Visual Analogue Scale (VAS), the Oswestry Disability Index (ODI), the Short Form Health Survey (SF-36), the vertebral fusion grade observed through a simple Rx, and the evaluation of possible complications or adverse reactions. Results: From the 14 patients enrolled in the trial, 3 were excluded due to screening failures (n = 11), 6 females and 5 males, with a mean age of 44. Out of the sample, 46% had disc disease compromising L4-L5 and the other 54%compromised L5-S1. After the implantation of autologous mesenchymal stem cells during vertebrae arthrodesis surgery, (VAS) and (ODI) were used to reevaluate the patients, showing improvements in both parameters after surgery. As for the radiological parameters, 100% of patients achieved lumbar fusion by the end of the study. No serious adverse effects related to the procedure were recorded. Conclusion: Degenerative disc disease is very common. Primarily affecting middle-aged patients, it has significant repercussions in both social and work-related activities. It is important to develop other treatment options that reduce adverse effects and the need for additional surgeries. The use of MSCs in vertebral arthrodesis procedures in patients with mono- segmental degenerative disc disease is feasible, effective and safe since 100% of patients achieved spinal fusion without serious adverse effects.

P189 - Nucleus Pulposus Cells Supernatant Induces Mesenchymal Stem Cells Differentiation Into Nucleus Pulposus-Like Cells

Arjun Sinkemani¹, Feng Wang¹, Zhi-Yang Xie¹, Lu Chen¹, Cong Zhang¹, Xiao-Tao Wu¹

¹Department of Spine Surgery, Zhongda Hosptial, Southeast University School of Medicine, Nanjing - China

Introduction: Intervertebral disc (IVD) is closely related low back pain, is the major cause of disability worldwide ¹, with more than 84% population experiencing pain in their life time ². IVD degeneration involves a reduction in the function and number of viable cells in the disc, mostly through cellular senescence and apoptosis³ and is very complicated and is usually due to some various biomechanical changes within the IVD and the causes of IVD degeneration is still debated with various environmental and genetic factors influencing in its pathogenesis ⁴. Biological and cell based therapies are on progress as an optional treatment for IVD degeneration. Many studies have also revealed that MSCs can also be differentiated into NP-like cells phenotype⁵. This study aimed to determine the newly defined healthy nucleus pulposus cells markers⁶; HIF-1α, HIF-2α, GLUT-1, Shh, Brachyury, Aggrecan, Collagen II, Carbonic anhydrase 3, Carbonic anhydrase 12, CD24, Cytokeratin 8, Cytokeratin 18, and Cytokeratin 19 of Sprague-Dawley rat, whether these markers can be expressed in MSCs under co-culture condition and could be identified the differentiation of MSCs into NP-like cells. Material and methods: NP cells and bone marrow derived MSCs from Sprague-Dawley rats were cultured under hypoxic medium at 37°C with 5% CO₂ and 2% O₂ and MSCs were co-cultured with NP cells supernatant with the concentration of 50% and 100% for 3, 5 and 7 days under hypoxic medium at 37°C with 5% CO₂ and 2% O₂. Differentiation of MSCs and expression of recommended newly defined young healthy NP cells phenotypes were evaluated by quantitative real-time PCR (qPCR), western blotting and immunofluorescence staining microscopy. Results: Western blotting results showed that Carbonic anhydrase 3, Cytokeratin 8, Cytokeratin 18, Cytokeratin 19 and Shh were expressed in MSCs after the co-culture with NP cells supernatant with the concentration of 50% and 100%. There was the significant increased expression treated with 100% NP cells supernatant compared with the MSC control group. While comparing the expressions treated with 50% and 100% NP cells supernatant co-cultured for 3, 5 and 7 days, there was a significant difference between these time intervals. Whereas, Carbonic anhydrase 3, Cytokeratin 19 and Shh showed increased expression in day 5 and day 7 compared to day 3 co-culture with the concentration of 100% NP cells supernatant. Cytokeratin 8 and Cytokeratin 18 showed significant increased expression in day 5 co-culture treated with the concentration of 100% NP cells supernatant compared to day 3 and day 7 co-culture. The increased expression and significant difference between these time intervals suggested that MSCs differentiation to NP-like cells. Conclusion: In our study, we analyzed the expression of these recommended healthy NP phenotypic markers in MSCs and the MSCs differentiation after co-culture with NP cells supernatant. Our results showed that NP cells supernatant plays a positive role in the differentiation of MSCs into NP-like cells. Co-culture with the concentration of 100% NP cells supernatant showed substantial increase expression of Carbonic anhydrase 3, Cytokeratin 19 and Shh in day 5 and day 7; while Cytokeratin 8 and cytokeratin 18 showed increased expression in day 5. The expressions of these markers were downregulated co-cultured with 50% concentration of NP cells supernatant and the expressions were upregulated with 100% concentration of NP cells supernatant especially on day 7. We can say that these higher expressions suggested that MSCs differentiation to NP-like cells. This study showed that NP cells can stimulate MSCs differentiation to NP-like cells with paracrine interaction between MSCs and NP cells under co-culture condition.

Keywords: co-culture, mesenchymal stem cell, intervertebral disc degeneration, cell phenotype, nucleus pulposus cell

References

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2. Walker BF. 2000. The prevalence of low back pain: a systematic review of the literature from 1966 to 1998. Journal of spinal disorders 13:205-217.

3. Jiang L, Zhang X, Zheng X, et al. 2013. Apoptosis, senescence, and autophagy in rat nucleus pulposus cells: Implications for diabetic intervertebral disc degeneration. Journal of orthopaedic research: official publication of the Orthopaedic Research Society 31:692-702.

4. Mayer JE, Iatridis JC, Chan D, et al. 2013. Genetic polymorphisms associated with intervertebral disc degeneration. The spine journal: official journal of the North American Spine Society 13:299-317.

5. Thorpe AA, Binch AL, Creemers LB, et al. 2016. Nucleus pulposus phenotypic markers to determine stem cell differentiation: fact or fiction? Oncotarget 7:2189-2200.

6. Risbud MV, Schoepflin ZR, Mwale F, et al. 2015. Defining the phenotype of young healthy nucleus pulposus cells: recommendations of the Spine Research Interest Group at the 2014 annual ORS meeting. Journal of orthopaedic research: official publication of the Orthopaedic Research Society 33:283-293.

P190 - Acute Back Pain: Are Admissions Being Prolonged Unnecessarily?

Humza Osmani¹, Kate Nicholls¹, Ali Dodhy¹, Jonathon Kitson¹

¹Department of Trauma and Orthopaedics, Lister Hospital, Stevenage - United Kingdom

Introduction: Back pain is a common pathology with up to 80% of the population reporting an episode during their lifetime in the United Kingdom. A cross sectional study has demonstrated 30% prevalence according to NICE. The UK Spinal Getting It Right First Time hospital review identified prolonged admissions as a concern. We sought to identify causes, and identify solutions including a standardised protocol which can be used nationally. Material and Methods: We identified the length of stay for acute back pain admissions and causes for delays through retrospectively collecting data over January and February 2017, including: Length of stay, Imaging (MRI ± CT) & timings; MDT discussions; Inpatient interventions; Analgesia prescribed and patients’ co-morbidities. Results were reviewed after a protocol was initiated. Results: Mean length of stay was 4 days; median was 2 days. Out of 23 patients 14 were admitted for more than 48 hours and 9 for less than 48 hours [17 of those had admissions due to disc pathology; 6 patients had infectious, cancer and fracture pathology]. Half of the patients were admitted as Cauda Equina Syndrome; all had negative scans. Two patients were transferred to another hospital for MRI overnight but returned due to a normal scan. Average time for in house MRI scans were 2 vs 12 hours for patients discharged < 48 hours and those who stayed > 48 hours, respectively. Recurrent causes for delays included poor initial analgesia being prescribed (including no neuropathic agents being prescribed on admission), whilst 60% of patients had a delayed discharge waiting for other parts of the MD, which were involved after 24-36 hours on average. Our protocol had advice for analgesia as recommended by the Pain Team, thus leading to better analgesia prescribing on admission, and led to earlier involvement of psychologists and physiotherapists, which led to better patient compliance for MRI scans, earlier diagnoses and earlier discharge by an average of a day. Conclusion: A simple protocol with involvement from the pain specialists, Physiotherapists and psychologists can lead to better pain control, faster diagnostics and also a reduction in time to discharge thus leading to beds becoming available and reduction in overall costs. Suggestion is a 24 hour MRI service at small hospitals may also improve discharge rates although costs need to be assessed.

P191 - Vertebral Endplate Changes, Possible Cause And Relation To Intervertebral Disc Degeneration

Zhigang Zhao¹, Lin Xie¹

¹Wuhan Puai Hospital Wuhan Puai Hospital, Wuhan - China

Introduction: Low back pain (LBP) is the world’s most common condition and use of many healthcare services. LBP may be caused by intervertebral disc degeneration. A completely intervertebral disc function unit should include disc, endplate and sub-endplate bone. There was disc changes (degeneration), endplate changes (defect) and sub-endplate bone changes (Modic changes) in LBP clinically. Material and Methods: In our paper, we focus on the endplate changes and divide them into three types. Type 1 endplate degeneration, calcification and ossification. Type 2 endplate defect and sub-endplate bone erosion adjacent to even into the disc. Type 3 endplate defect and disc erosion into the endplate which is called Schmorl’s noddle. Previous studies have presented that many possible pathogenetic mechanism causing the endplate changes. The aims of this paper are to propose two possible pathogenetic mechanisms how the endplate changes cause the up and down changes (disc degeneration and Modic changes). These are: a mechanical link: endplate changes cause abnormal stress transfer between disc and sub-endplate bone, the stress may cause the abnormal bone formation and remodeling of the sub-endplate bone. Then the abnormal bone which is the substratum of endplate and disc would cause the disc degeneration; a biologic cross-talk: there may be abnormal biologic cross-talk between the disc and sub-endplate bone through the endplate marrow contact channel (EMCC).

Results: When the endplate calcification or ossification (type 1), the EMCC will be blocked and the nutria from the sub-endplate bone marrow cannot be transferred into the disc, meanwhile, the metabolites from the disc cannot be transferred into the sub-endplate bone marrow. When the endplate defect (type 2 or type 3), the cytokines from the disc which are immunogenic will go to the sub-endplate bone marrow and cause the abnormal bone remodeling, meanwhile, the cytokines from the sub-endplate bone will be transferred into the disc and cause disc degeneration.

Conclusion: Vertebral endplate changes may be an important cause even origination of the intervertebral disc degeneration and it will the therapy point in the future.

P192 - Differences In Protein Profiling Between Degenerated And Herniated Disc – A Proteomic Analysis

S Rajasekaran¹, Chitraa Tangavel², Sharon Miracle Nayagam², Siddharth Aiyer³, Raveendran Muthurajan⁴, Kuppamuthu Dharmalingam⁵

¹Chairman- Dept of Orthopaedics, Trauma & Spine Surgery, Ganga Hospital, Coimbatore - India ²Research Co-Ordinator, Ganga Research Centre, Coimbatore - India ³Senior Registrar, Dept of Orthopaedics, Ganga Hospital, Coimbatore - India ⁴Professor, Centre For Plant Molecular Biology, Tamilnadu Agricultural University, Coimbatore - India ⁵Director, Aravind Medical Research Foundation, Madurai - India

Introduction: We report the first comparison of proteomic profile in the disc herniations and disc degeneration. Proteomics will assist in understanding the differential expressions of low abundant proteins (expressed at a magnitude of 10^-15, which might serve as a potent biomarker for understanding disease progression at various stages. Materials and Methods: We performed a comparative proteomic profiling of intervertebral disc tissue between 15 cases of disc herniation (DH) undergoing microlumbar discectomy and 5 cases of severe disc degeneration (DD) treated with lumbar fusion. Total proteins were extracted from all these samples using two buffers; radioimmuno precipitation assay buffer (RIPA) and 2% Sodium dodecyl sulphate (SDS). The resultant soluble and insoluble proteins were were cleaned using methanol: chloroform. Around 100 µg of total proteins were pre-fractionated on SDS-PAGE (Polyacrylamide gel electrophoresis) and proteins were analysed LC-MS/MS (Liquid Chromatography- tandem mass spectrometry) shotgun proteomics. Protein identification was performed using Proteome discoverer (PD) version 1.4.1.14 and Gene Ontology (GO) analysis for biological process, molecular function and cellular component of disc tissue was identified based on PD. Functional protein association network in the disc tissue were analysed using STRING database. Results: Total number of proteins identified in DH group was 945 and in DD group were 514. Pathways unique in DH are Vascular endothelial growth factor (VEGF) pathway, Transforming growth factor beta (TGF-β) signaling pathway, Platelet derived growth factor (PDGF) pathway, Epidermal growth factor (EGF) pathway, P-53 pathway, Wnt Signaling pathway, angiogenesis and apoptotic pathways. Presence of VEGF, TGF- β, PDGF pathway proteins such as Rho-GTPase activating 1 (VEGF), Inhibin beta A chain (TGF- β), PDGF factor subunit B, PDGF receptor like protein suggests angiogenesis. Similarly apoptotic pathway proteins Myosin 13 (Wnt signalling) and Heat shock protein family A5 supports IVD cells undergoing apoptosis during disc herniation. Interestingly analysis of the unique proteins of herniated discs using STRING protein functional association network shows around 106 proteins expressed in response to stress. Pathways unique to proteins to DD group are- axon mediated guidance pathway and vitamin D metabolic pathway. Protein semaphorin 3A (axon mediated guidance pathway) was observed in DD group which is a potent inhibitor of axon outgrowth and pathological innervations. Vitamin D binding protein levels were elevated in DD group. Analysis of the unique protein’s functional association using STRING revealed, around 12 proteins specific to oxidative stress, 12 proteins of receptor mediated endocytosis and 25 proteins involved in vesicle mediated transport in DD group. Conclusion: This is the first comparison of proteomic profile in the disc herniations and disc degeneration. The disc herniation group showed a more abundance of proteins compared to disc degeneration group. This abundance was due to pro angiogenic, pro apoptotic and stress response proteins. In contrast disc degeneration group had more evidence of receptor mediated endocytosis and vesicle mediated transport proteins.

P193 - Isolation, Caracterization And Comparison Between Mesenchymal Stromal Cells Obtained From Cervical And Lumbar Degenerative Intervertebral Discs

Carlos Marqués¹, David Pescador¹, Tony Setiobudy², Lourdes Ollero³, Juan Francisco Blanco¹

¹Spine Unit, Department of Orthopaedics, Complejo Asistencial Universitario de Salamanca, Salamanca - Spain ²Spine Unit, Department of Orthopaedics, Mount Elizabeth Medical Centre, - Singapore ³Department of Orthopaedics, Salamanca, Salamanca - Spain

Introduction: Degenerative disc disease etiology includes different factors such as genetics, metabolics and mechanics among others. One of these factors are cellular ones. Knowledge of the physiopathology of disc degeneration is crucial to solve this important health issue. The study of different cellular populations presented at the disc could contribute to this. The objective of this work is to compare mesenchimal stromal cells obtained from cervical and lumbar intervertebral discs. Material and Methods: Experimental comparative study between MSC isolated from cervical and lumbar degenerated intervertebral discs and a MSC sample obtained from bone marrow of the same patients. Morphological and immunophenotypical characteristics, as well as differentiation ability were studied. Results: There were 14 patients in the cervical group and 16 in the lumbar group. Isolation and expansion of MSC was possible in all cases. Bone marrow MSC were slightly smaller than intervertebral disc MSC. Immunophenotypic assessment of MSC from Intervertebral disc demonstrated that > 98% at the analyzed cells fullfilled general immunophenotypic criteria to define MSC: positivity for CD90, CD73 CD105, CD166 and CD106, as well as negativity for CD45, CD34, CD14, CD19 and HLA-DR antigen. Osteogenic, adipogenic and condrogenic differentiation was possible in all MSC obtained from bone marrow. MSC from lumbar ID were able to differentiate into both osteocytes and chondrocytes, but not to adypocites, while MSC obtained from cervical were able to differentiate into osteocytes and adypocites only. Conclusion: The demonstration of the presence of MSC into degenerated intervertebral discs supports the use of cellular therapy in this pathology.

P194 - Variants Of Il1a Associate With Lumbar Disc Degeneration And Modic Changes Of Lumbar Spine

Romain Perera¹, Harsha Dissanayake², Upul Senarath³, Lalith Wijayaratne⁴, Aranjan Karunanayake⁵, Vajira Dissanayake⁶

¹Department of Allied Health Sciences, Faculty of Medicine, University of Colombo, Colombo 08 - Sri Lanka ²Department of Anatomy, Faculty of Medical Sciences, University of Sri Jayewardenepura, Nugegoda - Sri Lanka ³Department of Community Medicine, Faculty of Medicine, University of Colombo, Colombo 08 - Sri Lanka ⁴National Hospital of Sri Lanka, Colombo 10 - Sri Lanka ⁵Department of Anatomy, Faculty of Medicine, University of Kelaniya, Ragama - Sri Lanka ⁶Human Genetics Unit, Department of Anatomy, Faculty of Medicine, University of Colombo, Colombo 08 - Sri Lanka

Introduction: Initiation and progression of lumbar disc degeneration (LDD) and Modic changes are genetically determined. Severity of LDD and Modic changes are associated with chronic mechanical low back pain. Pathophysiology of LDD and Modic changes is related to persisting inflammation and subsequent vascular and nerve in-growth in the disc. Interleukins are a group of local cytokines involved in the regulation of the inflammatory response. IL1α, IL1β and IL6 are the main interleukins involved in LDD and Modic changes (coded by IL1A, IL1B and IL6). This study evaluated the associations of single nucleotide variants (SNVs) of interleukin genes with the severity of LDD and Modic changes. Material and Methods: A descriptive cross sectional study was carried out on 106 patients with chronic mechanical low back pain who attended the rheumatology clinic, National Hospital of Sri Lanka, from May 2012 to May 2014. Severity of LDD and Modic changes in five lumbar levels were assessed on T1 and T2 sagittal lumbar MRI scan using Pfirrmann grading system and Modic classification system, respectively. DNA was extracted from venous blood using QIAamp DNA Mini Kit. Extracted DNA was quantified using the Quantus fluorometer with QuantiFluor® Double stranded DNA system. Nine SNVs in exonic regions of three genes (IL1A - rs2856836, rs1304037, rs17561, rs1800587; IL1B - rs2853550, rs1143634 and IL6 - rs1800796, rs1800795, rs2069849) were genotyped on a Sequenom MassARRAY iPLEX platform. Multivariable linear regression analysis was performed using PLINK 1.9. Severity of LDD/ Modic changes was used as the outcome variable and genotype of the respective SNV was treated as a quantitative variable coded 0, 1 or 2 to represent the number of variant allele, consistent with an additive genetic model. Age, gender and body mass index were used as covariates. Permutation tests with 10 000 permutations were performed to generate the significance levels empirically. In-silico functional analysis of significant SNVs was carried out using Provean, SIFT, PolyPhen and Mutation Taster. Results: Mean age was 52.42 ± 9.42 years. 74 (69.8%) were females. 27 (25.5%) were obese. All 106 patients who underwent MRI assessment had at least grade 2 LDD. Mean severity of LDD was 12.56 ± 2.88. Eighteen patients (17%) had Modic changes and type 2 Modic changes were common. Mean severity of Modic changes was 0.49 ± 1.22. All SNVs were in Hardy–Weinberg equilibrium. Each additional “G” allele of the rs2856836 variant, “C” allele of the rs1304037 variant, “A” allele of the rs17561 variant and “A” allele of the rs1800587 variant of IL1A were associated with progressive reduction in the severity of LDD (β = - 0. 22; p = 0.01) and Modic changes (β = - 0.20; p = 0.04). These four SNVs were in strong linkage disequilibrium. The rs17561 variant of IL1A was predicted as pathogenic by the PolyPhen prediction tool. Conclusion: SNVs of IL1A are associated with the severity of LDD and Modic changes in patients with chronic mechanical low back pain. Predictions of in-silico functional analysis of significant SNVs are inconsistent.

P195 - Functional Evolution Of The Surgical Treatment Of Degenerative Cervical Disc Disease At Two Levels By Means Of A Hybrid Technique Combining Cervical Arthrodesis And Disc Arthroplasty In Patients Of The Issemym Medical Center

René Crisanto Mora Ávila¹, Miguel Ángel Fuentes Rivera², Juan Enrique Guzman Carranza², Amado González Moga², Mizraim Castillo Urbina², Oscar Martín Callejas Salazar², Erick Jeancarlo Arreola Rodríguez¹, Romeo Palmer Becerra²

¹Departament of Orthopedics, ISSEM y M Medical Center, Ecatepec - Mexico ²Department of Spine Surgery, ISSEM y M Medical Center, Ecatepec - Mexico

Introduction: Total disc arthroplasty (TDA) is a technique that has increased in acceptance for the treatment of Degenerative Disease of Cervical Disc (DDCD). Clinical and radiological findings in the short and medium term are encouraging. Symptomatic patients with disc herniation or EDDC may be considered for a TDA. The questionnaire about the efficacy and safety of disc prostheses in patients with multilevel EDDC is maintained, due to the antecedent alterations in the concomitant facet joints and the degenerative bone changes of the adjacent segment. In cases of one to two affected cervical levels, Anterior Fusion Discectomy (AFD) continues to be the most accepted procedure with satisfactory clinical results and proven radiographic fusion of 90 to 100%. The efficacy and safety of a hybrid technique in a surgical time using TDA and AFD allows a particular analysis of each segment to restore movement when appropriate. Material and Methods: A retrospective, cross-sectional study was carried out between March 2014 and May 2017 at ISSEMYM Medical Center. We included patients with DDCD with two levels, with diagnosis of disc herniation as spondylosis, with anterior radicular affection, who were surgically operated with hybrid technique, placing intersomatic PEEK cages in the lower segment, and cervical disc prosthesis (Moby-C) in the upper segment. Exclusion criteria were patients with alterations in sagittal alignment of the cervical spine, as well as antecedent of previous surgery. A preoperative and postsurgical evaluation was performed with the Northwick Park Neck Pain Questionnaire (NPNPQ) and Neck Disability Index (NDI) scales. Patients were followed up with multiple clinical and radiographic examinations at 2 weeks, 2 months and 6 months. Results: A total of 31 patients were included, with a mean age of 48.2 years. There was an improvement in the NDI scale from 49.41 to 14.12, and on the NPNPQ scale from 74.93 to 28.26, with a p <0.001. The most commonly treated segment was C5-C6. Ten of the 11 patients underwent satisfaction with the procedure. Only one patient reported worsening of the scales used. One case of transoperative lesion of the laryngeal nerve was reported, with posterior neuropraxia of the laryngeal nerve, which returned 6 months after the intervention. Conclusion: We found that the hybrid technique in a surgical time, fusion - non - fusion seems to be a valid option in the treatment of symptomatic multilevel DDCD with different severity by segment, particularly in young and middle - aged patients, allowing preservation or reestablishment movement in moving segments without determining iatrogenic spinal instability or painful conditions secondary to the induced and forced mobilization of severely degenerate levels. In Mexico, there is little scientific evidence to support this novel technique, and although longer series are required with prolonged follow-ups, the proposed surgical strategy seems to be a safe and reliable way to avoid disease of the adjacent cervical segment.

P196 - Role Of Herpes Virus In Pathogenesis Of Vertebral Disc Degeneration

Saurabh Singh¹, Mani Kant Anand², Sunit Singh³, Anil Kumar Rai⁴, Siddalingeshwara G I², Prabhat Kumar⁵

¹Associate Professor, Department of Orthopaedics, IMS, BHU, Varanasi - India ²Junior Resident, Department of Orthopaedics, IMS, BHU, Varanasi - India ¹Associate Professor, Department of Molecular Biology, IMS, BHU, Varanasi - India ⁴Professor, Department of Orthopaedics, IMS, BHU, Varanasi - India ⁵Junior Resident, Department of Orthopaedics, IMS, BHU, Varanasi - India

Introduction: Multiple interdependent factors have been implicated in disc degeneration including reduced nutrient supply, hereditary factors, altered mechanical loading, age, up-regulated levels of pro-inflammatory cytokines and associated catabolic enzymes(cathepsin, lysozymes, matrix metalloproteinases), and cellular and extra-cellular biochemical changes. The purpose of my study was to assess the incidence of herpes viruses in intervertebral disc specimens from patients with lumbar disc degeneration. The intervertebral disc has a composite structure consisting of a gelatinous proteoglycan rich nucleus pulposus surrounded by a collagen-rich annulus fibrosus. The proteoglycan in the nucleus pulposus provides high water content within the nucleus pulposus, and in turn, contributes to sustain large loads applied to the vertebral body. The disc degeneration process affects several of the structures differently and apparently at different times during its progression .The intervertebral disc is responsible for carrying enormous amounts of compressive loading while maintaining flexibility. Materials and Methods: For my study total 20 patients were selected (12 male and 8 female with mean age of 41.6years) (age group 28 to 60). Patients with backache with more than 6 months of history without any radicular symptoms. Patients with history of trauma (recent or past), tumour, osteoporosis or any preceeding infection of viral or bacterial origin were excluded. Further diagnosis was confirmed through MRI. Disc was isolated through Microdissectomy procedure and stored in liquid nitrogen. The viral DNA was extracted using Invisorb® Spin Virus DNA Mini Kit (Stratec Molecular, GmbH, Berlin, Germany) from 20 human vertebral disc specimens. DNA isolated from tissue lysates was subjected to SYBR green based Real Time PCR for detection of HSV. An internal control gene BTK was used to check for positive amplification from the isolated DNA. The amplification was carried out in Qiagen Rotor Gene Q Real Time PCR machine (Qiagen, USA) using the following conditions: 95°C for 3 min; 40 cycles of 95°C for 20 s, 60°C for 20 s with plate read; and final melt analysis. A no template control reaction was also constituted with nuclease free water instead of template as a negative control. Results: SYBR green based real time PCR was carried out on samples 1 to 20 for detection of HSV using specific primers against HSV DNA Pol. The background amplification detected in NTC (non-template control) was that of the primer dimer. No amplification was detected from sample 2 and 12. Real-time PCR ct curves and Melt curves showed the specific amplification in 18 out of the 20 analysed samples . Conclusion: The relationship between viral infection and apoptosis has been widely investigated, clarifying the mechanisms of apoptosis induction by viruses .Based on the outcome of my study it can be concluded that Herpes Simplex Virus might play role in vertebral disc degeneration . Possibly herpes DNA acts as a factor that alters the structural characteristics of the matrix in the disc by modulating apoptosis and local inflammatory response.

P197 - Clinical Application Of Ceramics In Anterior Cervical Discectomy And Fusion: A Review And Update

Hirbod Nasiri Bonaki¹, Vafa Rahimi-Movaghar¹

¹Sina Hospital, Hasan Abad Squeare - Iran, Islamic Republic

Introduction: Anterior cervical discectomy and fusion (ACDF) is a reliable procedure, commonly used for cervical degenerative disc disease. For interbody fusions, autograft was the gold standard for decades; however, limited availability and donor site morbidities have led to a constant search for new materials. Clinically, it has been shown that calcium phosphate ceramics, including hydroxyapatite (HA) and tricalcium phosphate (TCP), are effective as osteoconductive materials and bone grafts. In this review, we present the current findings regarding the use of ceramics in ACDF. Material and Methods: A review of the relevant literature examining the clinical use of ceramics in anterior cervical discectomy and fusion procedures was conducted using PubMed, OVID and Cochrane. Results: HA, coralline HA, sandwiched HA, TCP, and biphasic calcium phosphate ceramics were used in combination with osteoinductive materials such as bone marrow aspirate and various cages composed of poly-ether-ether-ketone (PEEK), fiber carbon, and titanium. Stand-alone ceramic spacers have been associated with fracture and cracks. Metallic cages such as titanium endure the risk of subsidence and migration. PEEK cages in combination with ceramics were shown to be a suitable substitute for autograft. Conclusion: None of the discussed options has demonstrated clear superiority over others, although direct comparisons are often difficult due to discrepancies in data collection and study methodologies. Future randomized clinical trials are warranted before definitive conclusions can be drawn. This study was supported by Sina Trauma and Surgery Research Center, Tehran University of Medical Sciences and AOSpine of Middle East.

P198 - Mechanical Loading Leading To Intervertebral Disc Degeneration, Modulates Microglia Proliferation, Activation, And Chemotaxis

Stefania Elena Navone¹, Marianna Peroglio², sibylle Grad², Daniele Nicoli¹, Chiara Cordiglieri³, Marco Locatelli¹, Mauro Pluderi¹, Paolo Rampini¹, Rolando Campanella¹, Mauro Alini², Giovanni Marfia¹

¹Department of Neurosurgery, Policlinico di Milano, Milano - Italy ²AO Research Institute Davos, Davos, Switzerland, Davos - Switzerland ³Istituto Nazionale di Genetica Molecolare “Romeo ed Enrica Invernizzi”, Milano - Italy

Introduction: Low back pain (LBP) is a clinical, social, and economic burden, closely associated with intervertebral disc (IVD) degeneration (IDD) and disc herniation. IDD is a pathological process, which appears to be mediated mainly by abnormal production of pro-inflammatory molecules, such as a number of cytokines, chemokines and neurotrophins (NTs), by diverse cells types (1). The inflammatory mediators are produced and secreted not only by resident IVD cells, but also by circulating immune cells that could infiltrate IVD tissues. This inflammatory milieu exacerbates the overall degenerative condition, triggers a cascade of degenerative events, such as cell apoptosis and IVD extracellular matrix (ECM) disruption (2,3), and may eventually cause pain. In particular, a number of studies reported that human degenerated IVDs present inflammatory-like cells and immune cells, such as CD68+ macrophages, neutrophils and T lymphocytes (CD4+, CD8+), which infiltrate IVDs under chemotactic stimuli produced during degeneration (1,4). These evidences suggest that immune regulatory cells, either infiltrating in IVD tissues or resident in the spinal cord, play a crucial role in neuro-inflammation during IDD and in the onset of pain. The aim of the study is to assess the effect of the neuro-inflammatory microenvironment of a mechanically-induced degenerating IVD on neuro-inflammatory like cells such as microglial cells, in order to comprehend the role of this kind of cells in degenerative disc disease. Materials and Methods: Bovine caudal IVDs were kept in culture for 3 days in an ex vivo bioreactor under high frequency loading (10 Hz) and limited nutrition or in free swelling conditions as control samples. Conditioned media (CM) were collected, analysed for cytokine and neurotrophin content and applied to microglial cells for neuro-inflammatory activation assessment. Results: Degenerative conditioned medium (D-CM) induced a higher production of IFN-γ, IL-17, IL-8, and NGF from IVD cells than unloaded control conditioned medium (U-CM). Upon 48 h of co-incubation with microglia, D-CM stimulated microglia proliferation, activation, with increased expression of IBA1 and CD68, and chemotaxis. Moreover, an increment of nitrite production was observed. Interestingly, D-CM caused an upregulation of IL-1β, IL-6, TNFα, iNOS IBA1, and VEGF genes in microglial cells. Conclusion: Based on our results, the imbalance occurring during IVD degeneration in disc metabolism, degradation products, inflammatory secretome of IVD cells, and apoptotic events, establishes a local neuro-inflammatory microenvironment that activates pro-inflammatory, neuro-immune system cells, such as microglia. In conclusion, our results support for the first time the role of microglia in degenerative condition of IVD and provide striking evidence for a direct link between IVD high mechanical loading and activation and proliferation of neuro-inflammatory cells that exacerbate the degenerative conditions within the IVD and in the peridiscal space. This study provides evidences for an important role of microglia in maintaining IVD neuro-inflammatory microenvironment and probably inducing low back pain A better understanding of neuroinflammatory cells in underlying pathology may aid in the development of new potential local anti-inflammatory therapeutic options for degenerative disc disease and low back pain.

Acknowledgements

The study was partially supported by a grant from the Italian Ministry of Health, Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico (RC2016) and by University of Milan.

Conflict of Interest

The authors declare no conflict of interest.

References

1. Navone SE, Marfia G, Giannoni A, Beretta M, Guarnaccia L, Gualtierotti R, et al. Inflammatory mediators and signalling pathways controlling intervertebral disc degeneration. Histol Histopathol 2017 Jun; 32 (6): 523-542.

2. Antoniou J, Steffen T, Nelson F, Winterbottom N, Hollander AP, Poole RA, et al. The human lumbar intervertebral disc: evidence for changes in the biosynthesis and denaturation of the extracellular matrix with growth, maturation, ageing, and degeneration. J Clin Invest 1996 Aug 15; 98 (4): 996-1003.

3. Wuertz K, Haglund L. Inflammatory mediators in intervertebral disk degeneration and discogenic pain. Global Spine J. 2013 Jun; 3 (3): 175-84.

4. Kawaguchi S, Yamashita T, Yokogushi K, Murakami T, Ohwada O, Sato N. Immunophenotypic analysis of the inflammatory infiltrates in herniated intervertebral discs. Spine (Phila Pa 1976) 2001 Jun 1; 26 (11): 1209-14

P199 - Corticosteroid Administration To Prevent Complications Of Anterior Cervical Spine Fusion: A Systematic Review

Vafa Rahimi-Movaghar¹, Hirbod Nasiri Bonaki¹

¹Sina Hospital, Tehran - Iran, Islamic Republic

Introduction: Anterior cervical approach is associated with complications such as dysphagia and airway compromise. In this study, we aimed to systematically review the literature on the efficacy and safety of corticosteroid administration as a preventive measure of such complications in anterior cervical spine surgery with fusion. Material and Methods: Following a systematic literature search of MEDLINE, Embase, and Cochrane databases in July 2016, all comparative human studies that evaluated the effect of steroids for prevention of complications in anterior cervical spine surgery with fusion were included, irrespective of number of levels and language. Risk of bias was assessed using MINORS (Methodological Index for Non-Randomized Studies) checklist and Cochrane Back and Neck group recommendations, for nonrandomized and randomized studies, respectively. Results: Our search yielded 556 articles, of which 9 studies (7 randomized controlled trials and 2 non-randomized controlled trials) were included in the final review. Dysphagia was the most commonly evaluated complication, and in most studies, its severity or incidence was significantly lower in the steroid group. Although prevertebral soft tissue swelling was less commonly assessed, the results were generally in favor of steroid use. The evidence for airway compromise and length of hospitalization was inconclusive. Steroid-related complications were rare, and in both studies that evaluated the fusion rate, it was comparable between steroid and control groups in long-term follow-up. Conclusion: Current literature supports the use of steroids for prevention of complications in anterior cervical spine surgery with fusion. However, evidence is limited by substantial risk of bias and small number of studies reporting key outcomes. The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This study was supported by AOSpine of Middle East (AOSME) and Sina Trauma and Surgery Research Center, Tehran University of Medical Sciences (Tehran, Iran).

P200 - Primegrowth® Disc Cell Medium: A Novel Optimized Medium for The Culturing of Intervertebral Disc Cells

Michael Grant¹, Laura Epure¹, Yazeed AlSaran¹, John Antoniou¹, Fackson Mwale¹

¹Lady Davis Institute for Medical Research, McGill University, Montreal - Canada

Introduction: Investigating mechanisms, potential biologics, and scaffolds in the regeneration of the intervertebral disc (IVD) requires the use of model systems. Cell culturing of IVD cells is often employed as the first step in the development process. However, the native IVD cell environment is unique in terms of nutrient availability, metabolic exchange, O₂ tension, and osmolality. Notwithstanding, IVD cells are often cultured in standard DMEM medium subjecting the cells to a new environment that may alter responses to treatments. To this end, we have formulated a medium, PrimeGrowth^TM IVD Cell, in collaboration with Wisent Bioproducts (Montreal, Quebec) optimized for IVD cells. Material and Methods: Bovine nucleus pulposus (NP) and annulus fibrosus (AF) cells were cultured in PrimeGrowth^TM IVD Cell, DMEM, Alpha MEM, and Ham’s F12 media supplemented with 10% FBS and antibiotics. Cells were prepared for 3D culturing in alginate beads at a density of 2*10⁶ cells/mL for 12 days. A modified GAG assay was performed on the beads to determine proteoglycan content and the hydroxyproline assay was performed to determine collagen content. Gene expression of matrix proteins type I and II collagen and aggrecan were determined by qPCR. Cell viability was determined by counting live and dead cells in the beads following incubation with the Live/Dead Viability Assay kit (Thermo Fisher Scientific). Cell growth in the beads at the end of the incubation period was determined using Quant-iT dsDNA Assay Kit (Thermo Fisher Scientific). Results: PrimeGrowth^TM IVD Cell medium demonstrated consistency and significantly higher synthesis of Col II and aggrecan in both NP and AF cells. Although IVD cell viability and growth were unaltered for all media tested, certain culture media significantly increased the expression levels of Col I. Conclusion: Devising a medium unique for the culturing of IVD cells that better mimics their physiological environment may not only improve the translation of therapeutics but could better standardize results across laboratories. PrimeGrowth™ IVD Cell is the first ready-to-use media formulated to support the growth and maintenance of IVD cells with greater reliability, consistency and improved control.

Epidemiology

P201 - Epidemiological Profile of Patients With Traumatic Cervical Spinal Cord Injury: A 5-Year Tertiary Multicenter Retrospective Study in Negros

Yogendra Agrahari¹, Mark Gil D. Caliso¹, Gladys P. Tan¹, Renier D. Gerochi¹

¹Department of Orthopedic and Traumatology, CLMMRH, Bacolod City - Philippines

Introduction: The incidence of serious cervical spine injuries is low but associated rates of death and disability are high. In both British and Chinese studies, cervical spine is the most commonly affected region among traumatic spinal cord injuries (Lenehan, 2012). Cervical spinal cord injury is a devastating event for the patient and family. Mortality associated with cervical spine fractures is less studied^. This deficiency in the literature contributes to a lack of consensus on the optimal treatment of cervical fractures (Jackson, 2005). Materials and Methods: All patients admitted at Corazon Locsin Montelibano Memorial Regional Hospital (Negros Occidental, Philippines), Dr. Pablo O. Torre Memorial Hospital (Negros Occidental, Philippines), and Silliman Medical Center (Negros Oriental, Philippines), from January 2008 to December 2012 with cervical SCI secondary to trauma are included in the study. Charts of patients who met the inclusion and exclusion criteria were collected. Patients were categorized according to age group. After collection of data it was double entered in Excel file, and was analyzed using SPSS (version 16·0) software. Results: The study group comprised of 51 males (92.7%), and 4 females (7.3%). Patients’ age were from 15 to 76 years old, with mean age of 43.67 years ( ± 16.9, SD). Common cause of injury in 27 patients was fall (49.1%), followed by vehicular accident sustained by 25 patients (45.5%), and axial loading in remaining 3 (5.5%). Incomplete quadriplegia was sustained by 32 patients (58.2%), and complete quadriplegia (Frankel A) in the remaining 23 patients (41.8%). Eleven patients died in their hospital stay (20%), most had complete quadriplegia- Frankel A (n = 10; 43.5%), compared to incomplete quadriplegia (n = 1; 3.1%). Statistical analysis showed no significance between sexes (LRT = 0.064, df = 1, p = 0.8), as well as the cause of injury (x² = 0.833, df = 2, p = 0.659) for mortality of the patient. Analysis however, showed a significant relationship of the extent of paralysis and mortality (x² = 11.214, df = 1, p-0.001), as only 1 out of 31 patients with incomplete quadriplegia (3.1%) eventually expired, compared to 10 of 23 (43.5%) in completely quadriplegic patients. Last normal motor and sensory level did not show a significant statistical relationship to mortality (LR = 8.17, df = 6, p = 0.226). Radiographic abnormality, presence of spinal shock on admission, and patient’s age, showed no statistical significance to the mortality of the patient. Conclusion: This study showed that males of older adult group usually sustained cervical spinal cord injury either due to fall, or motor vehicular accident, with almost half having fracture-dislocation. Statistical analyses showed no significant relationship of age, sex, level of injury, and mechanism of injury to mortality. There is however a statistically significant relationship of extent of injury, particularly Frankel A, to eventual mortality of the patient. Surgical procedure can be a positive predictor for survival in cervical SCI patients.

P202 - Diagnosis of Suspected Cauda Equine Syndrome With Urgent Mri. The Real Life Scenario

Purnajyoti Banerjee¹

¹Department of Orthopaedics, Frimley Park Hospital, Camberley - United Kingdom

Introduction: Cauda equina syndrome (CES) represents acute compression of the lower spinal nerves resulting from various causes. They present with a diverse array of symptoms and signs including back pain, perianal paraesthesia, urinary of faecal retention or incontinence with loss of perianal sensation and tone. If the diagnosis is missed, permanent nerve damage leads to lifelong faecal, urinary and sexual dysfunction. Magnetic resonance imaging (MRI) is the investigation of choice in CES and urgent surgical decompression is indicated within 24 hours. Suspected CES patients are often a diagnostic dilemma in a district general hospital (DGH) as these patients frequently turn up out of hours or weekends when MRI facilities are unavailable. The orthopaedic team is then faced with the question whether to wait for the next available imaging slot or to refer these patients to a tertiary centre where definitive care is available. Objectives: To assess what is the positive strike rates for actual MRI proven CES cases in suspected cases an acute hospital in UK. Materials and Methods: We retrospectively reviewed all patients who were referred to a DGH as potential CES and their MRI scan outcome. Results: Between January 2014-December 2016, forty three patients (mean age 48.6 years, male [M]:15; female [F] 28) underwent MRI scans for suspected diagnosis of CES. Seven (16.2%) patients (mean age 71.4 years, M:2; F:5) had a positive scan and were transferred to the tertiary centre for surgery within 24 hours of presentation. The rest 36 were discharged after 24 hours of observation with no further need for surgery. This paper reflects our current practice of managing CES in a DGH. Conclusions: We recommend urgent clinical assessment and immediate MRI on presentation or transfer these patients to the nearest tertiary centre as soon as possible if MRI facilities are unavailable. If there is a likely delay in obtaining MRI, urgent transfer to the tertiary centre should be arranged rather than waiting for a slot to minimise long term morbidity that might result from delayed decompression. We recognise the huge resources need to set up this system with a relatively low yield but development of spinal network is a possible way forward to manage these issues.

P203 - Comparison of Spinopelvic Parameters Between Men and Women in Health and Disease

Sai Krishna M L V¹, Deep Sharma², Jagdish Menon³

¹Senior resident, Dept of Orthopaedics, Jipmer, Puducherry - India ²Addl Professor & Head, Dept of Orthopaedics, Jipmer, Puducherry - India ³Professor, Dept of Orthopaedics, Jipmer, Puducherry - India

Introduction: Ever since Legaye et al. in 1998 first described the importance of pelvic incidence as an important determinant of sagittal spinal balance, a number of other radiographic spinopelvic parameters have been defined. There are an increasing number of reports and studies from around the world signifying the role of these parameters in the maintenance of global spinal balance. Alteration in the normal values of the spinopelvic parameters has been implicated in causing accelerated degeneration, low back pain and even sagittal plane deformities. Certain pathologies are more common in males and some other in females. In this setting, it is extremely important to know whether there is any difference in the spinopelvic parameters between males and females. Thus in our study we aim to know the difference in sagittal spinopelvic radiographic parameters between men and women in health and disease. Materials and Methods: The study was approved by our institute review board and the ethical committee. A total of 221 subjects were included in the study. Of which 79 subjects were having spondylolisthesis deformity. Another group of 67 were having chronic low back pain without any deformity. The rest of the 75 were young, healthy and asymptomatic subjects. All the subjects were enrolled into the study after taking a formal consent. The parameters measured were pelvic incidence PI, pelvic tilt PT, sacral slope SS, thoracic kyphosis TK, lumbar lordosis LL. All measurements were performed using the Surgimap spine software. The values thus obtained were compared between men and women. Results: In the asymptomatic group the mean values of parameter in males were- PI-47.19, SS-37.48, PT-9.71, LL- 55.52, TK- 24.43. In females were- PI-48.11, SS-33.81, PT-14.31, LL-54.35, TK-23.87. In the low back pain group the mean values of parameters in males were- PI- 46.00, SS-34.79, PT-11.67, LL-50.54, TK-28.54. In females were PI-49.19, SS-35.95, PT-13.14, LL- 50.58, TK-25.81. In the listhesis group the mean values of parameters in males were- PI- 56.80, SS-38.60, PT-18.20, LL-55.60, TK-31.40. In females PI-65.89, SS-44.50, PT-21.51, LL-60.62, TK-25.09. Conclusion: PI, PT was higher in women in all the three groups. But the difference was significant enough for PI in listhesis group and for PT in asymptomatic group. TK was lower in women in all the three groups but the difference was not significant enough. For LL and SS the variations were not the same among the three groups and the difference was also not significant enough.

P204 - Novel Oral Anticoagulants (NOAC) In Patients Undergoing Spine Surgery

Davide Croci¹, Martina Dalolio¹, Maria Kamenova¹, Raphael Guzman¹, Luigi Mariani¹, Stefan Schaeren², Jehuda Soleman¹

¹Department of Neurosurgery, University Hospital Basel, Basel - Switzerland ²Department of Spine Surgery, University Hospital Basel, Basel - Switzerland

Introduction: Novel oral anticoagulants (NOACS) were shown to be as effective as vitamin K antagonists for the prophylaxis and treatment of thromboembolism. Therefore, the number of patients treated with NOACS is increasing, and neurosurgeons and spine surgeons need to become more familiar with their risks, limitations, and management. Despite growing clinical relevance, guidelines on the perioperative management of these patients are still lacking. The aim of the study was to present a cohort of patients who were treated with NOACS and underwent spine surgery, and to analyze the occurrence of postoperative bleeding events and factors which might influence bleeding rates in these patients. Material and Methods: Out of 2777 Patients who underwent spine surgery between January 2014 and December 2016, 82 (2.9%) were under NOACS preoperatively. The rate of peri- and postoperative bleeding events, postoperative thromboembolic events, hematologic findings, morbidity, and mortality were reviewed. A sub-analysis of factors influencing the bleeding risk of these patients and the bleeding rate depending on the preoperatively discontinuation time of NOACS, with a cutoff of 24, 48 and 72 hours, was additionally completed. Results: The overall rate of perioperative bleeding was 4.9% (n = 4) and the rate of postoperative anemia needing packed red blood cell (PRBC) substitution was 6.1% (n = 5). The mean preoperative discontinuation time of NOACS was 3.5 days ( ± SD 1.7 days, range 1 - 14 days) in the patients experiencing a bleeding event, as opposed to 4.2 days ( ± SD 3.6 days, range 0 - 20 days) in patients without a bleeding event, showing no significant difference. Preoperative discontinuation time of less than 24 hours increased significantly the rate of PRBC substitution in the postoperative period (p = 0.007). Postoperative resumption time of NOACS did not seem to significantly affect bleeding events. Conclusion: Based on our cohort the postoperative bleeding rate in patients undergoing spinal surgery treated with NOACS was 4.9%. Preoperative discontinuation time under 24 hours seems to significantly increased the rate of postoperative PRBC substitution.

P205 - Spine Fractures Due to Ski and Other Winter Sports in the Chilean Andes During The 2017 Season: Injury Profile and Treatment

Ratko Yurac¹, Juan José Zamorano¹, Felipe Novoa¹, Alvaro Silva¹, Bernardo Merello¹, Bartolome Marré¹, Carolina Avilés¹, Juan Pablo Torrens¹, Matías Delgado¹

¹Clinica Alemana - UDD, Santiago - Chile

Introduction: During the last years, we have detected a progressive increase in the number of patients treated in our center for spine injuries due to winter sports accidents. Currently, no nationwide registry of these injuries has been established in Chile, so there is no information regarding their national incidence and prevalence. We present a case series of patients with spine fractures after a winter sport-related accident treated in a single center, focusing on the injury profile and treatment. Materials and Methods: Medical records and imaging of patients treated in our center for a spine fracture due to a winter sport-related accident during the 2017 season were reviewed. We recorded demographics, expertise level, injury mechanism, use of protective gear, type of spine fracture, associated injuries and treatment modality. Results: Case series of nine patients (77.8% female, median age 21 years [7-55]), with a total of 17 spine fractures. Four patients (44.4%) were experts (one snowboarder and three skiers), four skiers had an intermediate level and one patient (11.1%) was injured while using a sled. None of the patients were using spine protective gear at the time of the accident. Regarding the injury mechanism, four patients (44.4%) had a same-level fall, one patient (11.1%) was hit by another skier and four (44.4%) had a fall from a height. Most of the accidents (8/9, 88.9%) occurred in regulated tracks and only one patient (11.1%) was injured while skiing off-track. All the accidents occurred between 10 AM and 4 PM (five (55.6%) between noon and 4 PM). The thoracolumbar spine (T11-L2) was the most frequently affected segment (6 patients, 66.7%), followed by the thoracic spine (T1-T10) with two patients (22.2%), while only one patient (11.1%) presented an L5-S1 injury. Six patients (66.7%) had AO type A fractures (three subtype A1, two subtype A3 and one subtype A4), while the other three (33.3%) had AO type B2 injuries. Only one patient (11.1%) presented neurologic impairment (cauda equina syndrome), which resolved completely after surgery. None of the patients had associated injuries. Regarding the treatment modality, four patients (44.4%) required surgery for a posterior instrumented fusion (AO subtype A4 and type B2 injuries), while the other five patients (55.6%) were treated conservatively with a spine brace (AO subtype A1 and A3 fractures). Conclusions: Spine fractures must be ruled out in patients reporting back pain after a ski-related accident, even in the case of a same-level fall. In our series, compression injuries (AO type A) were more frequent, neurologic impairment was rare and some patients required surgical treatment. The incidence of these injuries is progressively increasing, so further, nationwide, research is needed to determine their real extent and develop local prevention measures.

P206 - The Impact of Data Quality Assurance and Control Solutions on The Completeness, Accuracy and Consistency of Data in A National Spine Registry (NSCIR)

Pegah Derakhshan¹, Zahra Azadmanjir¹, Khatereh Naghdi¹, Mahdi Safdarian¹, Mohammad Reza Zarei¹, Seyed Behzad Jazayeri¹, Mahdi Sharif-Alhoseini¹, Kazem Zendehdel², Abbas Amirjamshidi¹, Zahra Ghodsi¹, Morteza Faghih¹, Mahdi Mohammadzadeh¹, Zahra Khazaie¹, Shayan Abdollah Zadegan¹, Aidin Abedi¹, Farideh Sadeghian¹, Vafa Rahimi Movaghar¹

¹Sina Trauma and Surgery Research Center, Tehran University of Medical Sciences, Tehran - Iran, Islamic Republic ²Cancer Research Center, Cancer Institute of Iran, Tehran University Medical of Sciences, Tehran - Iran, Islamic Republic

Introduction: Data quality is of enormous importance in disease registries as the bases for research, evaluation and policy-making in the health system. The complexity of data quality assurance and control processes in the registries varies depending on scope, the number of data sources, methods of data collection, and expertise level of registers. The aim of the present study was to develop and evaluate a systematic plan to improve data quality and control solution for National Spinal Cord and Column Injury Registry of Iran (NSCIR-IR)-a multicenter hospital-based registry. Material and Methods: Our plan to improve data quality included quality assurance (i.e., preventive actions before starting the registry) and quality control (i.e., corrective actions during execution of the registry). Quality assurance started with data set preparation. We considered availability and accessibility of each data item since they seemed to have major impacts on completeness. In addition, the reliable sources for each data item were specified in the data gathering guideline. Other solutions for data quality assurance were considered in designing paper-based case report forms and our software. We designed structured paper forms and minimized using the free text. In addition, to prevent the entry of incorrect data into the software, validation rules were defined and implemented including 70 semantic rules, 18 syntactic rules, seven temporal rules and 13 rules for acceptable value range. For quality control, trained staff were employed as quality reviewers to identify any defect, inaccuracy and inconsistency of the data. A set of functions was implemented in the software to check data by reviewers, to feedback to registrars and for correction. Finally, we evaluated the effects of this plan on the completeness, accuracy and consistency of our registry data through a seven-month pilot phase. Results: Completeness was 100% for 20 socio-demographics data items (e.g. Birth date, gender, occupation, etc.), 97% for national ID and 92.3% for education level. Completeness was 100% for the admission data (n = 5), injury mechanism including external cause code (n = 17), emergency department (n = 11), comorbidity (n = 9), type, level and number of vertebral injury (n = 6), spinal cord injury (n = 2), concomitant injuries (n = 2), interventions (n = 19), complications and outcome (n = 13) and also American Spinal Injury Association(ASIA) impairment scale (n = 163). Completeness was 100% for all of the emergency medical services data except arrival and transfer time (99.43%) and oxygen saturation (48.93%). Consistency was 100% for all the data. Accuracy of all data collected by two centers located in Tehran was 100%. Accuracy of type, level and number of vertebral injury (n = 6) and interventions (n = 19) from our collaborating center outside Tehran was 100%, but it was not evaluable for other data due to lack of access to primary data source. Conclusions: Current approach for quality assurance and control of consistency was fully effective. Regarding completeness, our strategy led to a decrease in the missing data. Although designed solutions for the assurance and control of accuracy were effective to registry centers in Tehran, it is necessary to develop an appropriate technique to control the accuracy of the recorded data by centers outside of Tehran.

P207 - Global Incidence OF Traumatic Spinal Cord Injury: A Systemic Review of Published and Unpublished Literature

Seyed Behnam Jazayeri¹, Maryam Chalangari¹, Mahdi Safdarian¹, Shayan Abdollah Zadegan¹, Seyed Behzad Jazayeri¹, Vafa Rahimi Movaghar¹

¹Sina Trauma and Surgery Research Center, Tehran University of Medical Sciences, Tehran - Iran, Islamic Republic

Introduction: Traumatic Spinal Cord Injury (TSCI) is a destructive but preventable condition with high morbidity and mortality. Because of the absence of curative treatment for SCI, there is a strong necessity to understand TSCI epidemiologic characteristics and etiologies to promote practical preventive policies. The purpose of this study is to gather the available information and update the literature to understand the TSCI epidemiology worldwide better. Material and Methods: Medline, PubMed, and EMBASE databases were searched systematically using a predefined search protocol. The grey literature was searched separately by, multiple personal communications, website searching, and reference checking of related papers. Results: Title of 1238 articles was screened, and data of 122 papers as well as five books, two theses, and 17 websites was extracted. Epidemiologic data concerning TSCI was available for 46 countries of the world. The epidemiologic data including incidence and etiology of TSCI is described separately for each country. The primary etiologies of SCI were road traffic injuries, fall or violence in most of the world. The incidence of TSCI in this study ranged from 3.6 patients per million in Canada to 195.4 in Ireland. Northern American, European countries along with Australia demonstrated a decreasing or stable pattern of TSCI during the past decade. The extent of available data supports the fact that these countries have implemented preventive strategies based on the available epidemiologic data which has been effective in preventing the occurrence of TSCI. Conclusion: There is an increasing number of publications in the literature focusing on the epidemiologic data of TSCI. In this study, we could identify twenty-one out of 122 papers reporting epidemiologic data on TSCI in a 3-year period (2013-2016) which is more than 20% (21/101). Developing countries lack a central organization in registry or report of TSCI. In the literature, there is no standard dataset in the report of TSCI. It is suggested to develop a standard dataset in the report of TSCI.

P208 - Protocol and Progress of the International Whiplash Core Outcome Set Project

Aidin Abedi¹, Jeffrey Wang¹, Zorica Buser¹

¹Department of Orthopaedic Surgery, Keck School of Medicine, University of Southern California, Los Angeles - United States

Introduction: Whiplash injury is a common aftermath of the motor vehicle accidents and results in long-term disability in up to 50% of the affected individuals. Despite the tremendous research focusing on whiplash, pathophysiology and the treatment of choice for this condition remain controversial. This study describes the protocol, feasibility and progress of an international project for development of a core outcome set for whiplash. Materials and Methods: This project includes a series of comprehensive systematic reviews which will describe the trend of use of outcome domains and measurement instruments in whiplash trials, and will summarize the evidence on measurement properties of measurement instruments in whiplash. This information will be used to inform an international panel of experts, to provide the scientific evidence for two Delphi studies which will identify the minimum outcome domains and measurement instruments to be used in whiplash trials. Results: Our scoping search of four major electronic literature databases identified 3745 potentially relevant research articles, among which 251 are eligible for inclusion in the reviews of measurement properties. Preliminary screening of these articles shows various measures are available for each health-related outcome domain, which confirms the feasibility of development of a core outcome set. Separate studies focusing on measures of pain, neck mobility, disability and sensory testing are in progress. Conclusions: The robust methodology of this project ensures successful development of a core outcome set which is intended to improve the quality of future whiplash research.

P209 - A Systematic Review of The Reliability, Validity and Responsiveness OF Neck Mobility Measures in Whiplash

Aidin Abedi¹, Jeffrey Wang¹, Zorica Buser¹

¹Department of Orthopaedic Surgery, Keck School of Medicine, University of Southern California, Los Angeles - United States

Introduction: Neck mobility is a critical index for initial assessment of whiplash injuries and subsequent assessment of the response to treatment in chronic phase. This systematic review summarizes the evidence on validity, reliability and responsiveness of available measures in whiplash population. Materials and Methods: Present study is part of a series of reviews undertaken as an initial step for the international whiplash core outcome set project. PubMed, Embase, MEDLINE and CINAHL were queried for studies on measurement properties (i.e., reliability, validity and responsiveness) of measurement instruments in whiplash. This literature search was performed using a highly-sensitive published search filter for studies on measurement properties. Studies focusing on neck mobility measures were included in this review. The Consensus-based Standards for the selection of health Measurement Instruments (COSMIN) checklist was used for quality appraisal of the included studies, and the quality of the results for each measurement property was evaluated using a pre-defined criteria and rated as positive (sufficient), negative (insufficient) and indeterminate. Results: Electronic literature search captured 6,349 records, of which thirteen were included in this review after duplicates removal, title, abstract and full-text screening. These included twenty different evaluations on reliability, measurement error and construct validity of nine different measurement methods. These measures covered different aspects of neck mobility, such as range of motion, motion velocity, position error and endurance. The methodological quality was good in four studies and fair/poor in the rest of the studies. Assessment methods included radiography, ultrasonography, electromagnetic motion tracking, electrogoniometery, three-dimensional kinematic video processing, and protractor range of motion assessment. Overall, the preliminary results of this review showed good discriminative validity of the adapted Grimmer’s test, Elite kinematic assessment, Fastrak motion tracking system and Zebris cervical range of motion system. Conclusions: Despite the good results for validity of some of the mobility measures in whiplash, high quality studies are needed to fill the gap of reliability and responsiveness studies.

P210 - Functional Outcome of Spinal Surgery in Patients Over 90 Years

Jonathan Rychen¹, Sarah Stricker¹, Stefan Schaeren¹, Gregory F. Jost¹

¹Spine Surgery, University Hospital Basel, Basel - Switzerland

Introduction: Increased life expectancy into the 10th decade has lead to indications for spine surgery in this very old age group, but data to counsel these patients on the risks and outcome is lacking. We reviewed our experience to shed light on the implications and prognosis of spine surgeries in this age group. Material and Methods: The files of all patients who were 90 years or older at the time of spinal surgery between 2006 and 2016 were analyzed to retrieve indication for surgery, complications, extent of surgery, blood loss, length of hospital stay, outcome after 6 weeks, survival, dependency, mobility, and comorbidities. Patients and their physicians were phoned for missing data. Results: 73 patients were included. Mean age was 91.5 (90 - 97). 58% were female and 42% were male. 54.8% had degenerative and 35.6% traumatic pathologies. 84% were operated electively and 16% emergently. Mean operated levels was 2.1 (range 1-5) for elective and 3.8 (range 1-7) for emergency cases. 33% of elective and 58% of emergent surgeries were stabilized. 21.3% had minor and 21.3% major complications in the elective surgery group. In the emergency surgery group, 75% of the patients experienced major complications and 0% minor complications. After 6 weeks, 71.2% felt better, 15.1% the same and 2.7% worse than before the surgery. 40% of the emergency patients died within 3 months after surgery compared to 0% in the elective group. In the elective group, 62.2% of the patients reached the normal life expectancy of their age and gender group. In the emergency group, 37.5% of the patients reached the normal life expectancy. Conclusion: Elective spinal surgery in patients over 90 years is not reducing life expectancy. Moreover, it seems to have a good functional outcome for well selected patients. Emergency spinal surgery (trauma cases, more extensive surgeries) is associated with a high complication rate and a higher mortality, even if spinal symptoms are improved.

P211 - Differential Psychometric Properties of Eq-5d-5 L and SF-6D Utility Measures in Patients with Low Back Pain

Prudence Wing Hang Cheung¹, Carlos King Ho Wong², Jason Pui Yin Cheung¹

¹Department of Orthopaedics and Traumatology, The University of Hong Kong - Hong Kong ²Department of Family Medicine and Primary Care, The University of Hong Kong - Hong Kong

Introduction: LBP is a common musculoskeletal disorder requiring multiple diagnostic tests and treatment, these can incur high medical costs. It is thus desirable to have appropriate utility measure for cost-utility analysis of various LBP-related interventions and their cost-effectiveness. This prospective study aims to examine the acceptability, validity and reliability of the EuroQoL 5-dimension 5-level (EQ-5D-5 L) and Short-Form 6-Dimension (SF-6D) health utility measures in patients with low back pain (LBP). Materials and Methods: Health-related quality of life (HRQoL) questionnaires including the generic 12-item Short Form Health Survey (SF-12), EQ-5D-5 L and low back/back-related questionnaires were administered at a specialty outpatient clinic. Responses to SF-12 items were transformed to SF-6D utility scores using the Hong Kong population scoring algorithm derived by Standard Gamble whereas response to EQ-5D-5 L were mapped onto EQ-5D-3 L response via interim mapping algorithms and then converted to EQ-5D-5 L utility scores using the Chinese-specific value set. Construct validity was determined by evaluating Spearman correlation between SF-12 scores and EQ-5D-5 L utility scores. Correlation between back-specific questionnaires and HRQoL scores were also assessed. Results: A total of 100 patients were recruited. No significant (>15%) floor and ceiling effects were observed for utility scores of EQ-5D-5 L and SF-6D. Detailed proportion of respondents for each EQ-5D-5 L domain indicated that Pain/Discomfort domain was the most prevalent problem. The SF-6D utility score had a strong Spearman rank correlation with SF-12 domain and summary scores (0.600-0.855). Moderate-to-strong Spearman rank correlations were observed between EQ-5D-5 L score (0.455-0.700) and SF-12 domain and summary scores, and between EQ-5D-5 L and SF-6D scores (0.625). Adequate construct validity was evident as both utility scores conceptually measure the similar construct. Patients with no history of previous spine surgery or no disc degeneration had significantly higher EQ-5D-5 L scores (p = 0.047; p = 0.010). Significant correlations were observed between both EQ-5D-5 L and SF-6D scores and back-specific questionnaires. Conclusions: Both EQ-5D-5 L and SF-6D instruments appeared to be applicable and valid measures in assessing the HRQoL of LBP patients. This is the first study to examine the differential psychometric properties and validation of the use of EQ-5D-5 L and SF-6D in the Chinese LBP population. The impact of utility score selection on assessing the effectiveness of clinical interventions for LBP can now be explored.

P212 - Epidemiology, Imaging and Clinical Features of Familial Cervical Ossification of Posterior Longitudinal Ligament

Zhen Chen¹

¹Department of Orthopedics, Peking University Third Hospital, Beijing - China

Introduction: Through the analysis of the imaging data of the members of the familial ossification of the posterior longitudinal ligament (OPLL) in cervical spine, basic characteristics and laws of epidemiology, imaging and clinical features of the familial aggregation of the ossification of the posterior longitudinal ligament was revealed. Material and Methods: From 2011 to 2016 in patients who were diagnosed as cervical ossification of posterior longitudinal ligament, we screened out the families of cervical ossification of posterior longitudinal ligament, which performed familial aggregation by asking family history. During hospitalization, we routinely treat patients and their relatives with the inheritance of cervical ossification of the posterior longitudinal ligament, and, in the postoperative follow-up, we finally selected six probands and their families and collected the relevant imaging and symptom data.

Results

1. The prevalence of radiological cervical OPLL was 33%. The prevalence of OPLL was about 24.5%, all of which showed obvious familial aggregation, and there was no significant difference in gender.

2. The average age of the imaging OPLL members was 49.5 years old, and the average number of involved segments was about 3.6;and the average number of male to female was 3.8:3.4.The average age of the patients with OPLL was 52.8 years old, and the average number of involved segments was 4.3 (male: female 4.6:4.0).

3. The average age of onset of patients with OPLL was 47.2 years old, of which the average age of the male to female was 50:44.

4. The corresponding number and average age of the imaging OPLL is: Focal type 5 cases (aged 38), Segmental type 3 cases (aged 53), Continuous type 4 cases (aged 50), Mixed type 7 cases (aged 56). Among them, the younger generation of cervical spine OPLL was all focal type.

5. By observing the OPLL in 19 cases, it was found that the OPLL was most likely to occur in the C4-6 vertebral body, C5 had the highest frequency (21.7%), and decreased in the upper and lower directions.

6. It was found that the C5 and C6 segments corresponded to the lowest age, while the values of the two sides gradually increased.

7. In this study, the incidence of cervical trauma accounted for 8% of the total number of patients. Neck pain as the first symptom was the most, accounting for 69% of all patients. The highest incidence of symptom is upper limb pain and numbness.

Conclusion: The incidence of familial cervical OPLL is higher than that of the general population and there was no significant difference in gender. The imaging findings of familial OPLL have some features compared with those of the general population. However, there were no significant differences in its symptomatology between the familial and the general population.

P213 - Prevalence, Consequences and Predictors of Low Back Pain Among Nurses in A Tertiary Care Setting

Sameh Abolfotouh¹, Khaled Faraj¹, Gemeh Moammer²

¹Mediclinic City Hospital, Dubai - United Arab Emirates ²Grand River Hospital, Kichner - Canada

Introduction: Nursing is a profession with high incidence and prevalence of low back pain (LBP), with its medical and professional consequences. These prevalence rates vary among countries, and with various measurements have been used to determine LBP. Individual and work-related factors are regarded as causal factors for many back injuries. The aims of study were: 1) to estimate the prevalence of LBP using different measures, 2) to determine medical and professional consequences of LBP, and 3) to determine the associated factors and significant predictors of LBP. Material and Methods: A cross-sectional study was conducted among 254 nurses from different departments/wards at Hamad General Hospital (HGH), Doha, Qatar over two months (January & February, 2015). Self-administered modified Nordic questionnaire was used to collect data regarding five different measures of LBP, its medical and occupational consequences and individual/lifestyle and work-related risk factors of LBP. Descriptive and analytic statistical analyses were done using Chi square and multivariate logistic regression techniques. Significance was considered at p < 0.05. Results: The findings of this study broadly confirm the high levels of back pain in nursing, with a one year prevalence of LBP of 54.1% for LBP of at least one day, % for Chronic LBP, % for seeking sick leave seeking LBP, and % for medical treatment seeking LBP. Difficult or impossible Activities daily living were reported due to LBP in; climbing stairs (50.7%), walking (42.8%), standing up (39.9%), sleeping (33.3%), getting out of bed (30.4%) and wearing clothes (20.3%). Work stop due to LBP was reported by 76.8% of nurses, with 2.03 ± 3.09 days within the last year. Treatment was sought in 58.7% by medical care, and 15.9% by physiotherapy, while seeking rest days and/or sick leave was sought in 50.8% of nurses with LBP. Sports practice (p = 0.003), office work (p < 0.001) and exposure to physical stress (p = 0.002) were the only significant predictors of LBP among nurses, when logistic regression analysis was conducted. Conclusion: The prevalence of LBP among nurses at HGH is high and should be actively addressed, however it was not a major cause of sick leave. Preventive measures should be taken to reduce the risk of lower back pain, such as arranging proper rest periods, educational programs to teach the proper use of body mechanics and sports activity programs.

P124 - Consideration On The Neuropathic Pain Due To Syringomyelia Associated With Chiari I Malformation

Toshitaka Seki¹, Kazutoshi Hida², Kazuyoshi Yamazaki¹, Kiyohiro Houkin¹

¹Hokkaido University Graduate School of medicine, Sapporo - Japan ²Sapporo Azabu Neurosurgical Hospital, Sapporo - Japan

Introduction: Syringomyelia associated with Chiari malformation type I exhibits various symptoms. In particular, neuropathic pain is refractory and markedly impairs the patient’s daily life. We examined the relationship between pre-operative syringomyelia morphology and neuropathic pain. Method: We examined 24 patients with np due to syringomyelia associated with Chiari I malformation. We statistically analyzed about the duration of illness and the age at surgery between the patients with np and the patients without np. Furthermore, we classified the morphology of syrinx into a deviated type (D), enlarged type (E), central type (C) and mosaic type (Mo) using T1 weighted axial image. Moreover, we considered the correlation between the morphology of the syrinx and np. Also, we performed Mann-Whitney U test between the presence or absence of np and the presence or absence of type D. Results: The median age at surgery was 27.5 years old. The median duration of illness was 24 months. Of 24 patients, 11 patients had pre-operative np. Out of 11 patients, only one patient showed np free in the final follow-up period. In the patients with np, the preoperative morphology of syrinx was nine patients with D, one patient with E, one patient with C. There was no patient with mosaic type. On the other hand, in the patients without np, the preoperative morphology of syrinx was three patients with D, seven patients with E, two patients with C, and two patients with Mo. The correlation between np and the morphology of syrinx was correlated with type D and type E. Also, Type D showed a significant neuropathic pain in this study. Conclusion: We could prove that there was the correlation between the morphology of syrinx and np in syringomyelia associated with Chiari I malformation.

Keywords: Chiari I malformation, magnetic resonance imaging, neuropathic pain, syringomyelia

Imaging

P215 - Analysis Of Reliability And Reproducibility Of Manually And Automatically Measured Parameters In Computed Tomography Imaging Of The Injured Spine

Sven Vetter¹, Yiheng Chen¹, Shiyao Liao¹, Paul A. Grützner¹, Stefan Matschke¹, Michael Kreinest¹

¹BG Trauma Center Ludwigshafen, Department of Trauma Surgery, Ludwigshafen - Germany

Introduction: Advancements in imaging software products provide increasing automatic measurements of parameters characterizing vertebral body fractures such as the local sagittal angle, scoliosis angle and the disc height. The consistency of these automatically measured parameters compared to manually measured parameters is still unclear. Thus, the aim of the current study was to analyze the reliability of automatically measured parameters in computed tomography imaging of the injured spine. Material and Methods: First, reliability and reproducibility of the manual measurement (mediCAD spine 3D, Hectec, Germany) was analyzed by measuring the above mentioned parameters by three experienced observers at two time points (with an interval of 7 days). Inter-observer reliability as well as intra-observer reproducibility was analyzed by intraclass-correlation. Only if reliability and reproducibility of the manual measurements were good to excellent^1,2 (intraclass correlation coefficient (ICC) = 0.70 – 1.00), comparison to the automatic measurement (mediCAD spine 3D) was performed by t-test. Statistical analysis was performed with SPSS (IBM, USA). Results: Inter-observer reliability was excellent for manually measured local sagittal angle (ICC = 0.97) and good for manually measured scoliosis angle (ICC = 0.80). Furthermore, intra-observer reproducibility was excellent for manually measured local sagittal angle (ICC = 0.97) and good for manually measured scoliosis angle (ICC = 0.81). Compared to the manual measurement of the local sagittal angle no significant difference was seen in the automatic measurement (3.2 ± 12.8° vs. 2.6 ± 12.1°; p = 0.208). However, automatic measurement of scoliosis angle differs significantly from manually measured values (3.7 ± 3.1° vs. 4.8 ± 3.6°; p = 0.023). Analyzing the manual measurements of the disc height, inter-observer reliability and intra-observer reproducibility was poor (ICC = 0.61 and ICC = 0.36, respectively). Thus, comparison to automatic measurement was not performed for disc height. Conclusion: Local sagittal angle can be measured reliable by automatic and manual measurement. But other parameters such as scoliosis angle remain with an inaccuracy in the automatic measurement. Other studies³ confirm such discrepancys in the range of 20%. However, some parameters such as the disc height could not be detected reliable even with manual measurement. Difficulties correlating to the identification of anatomical landmarks (such as spondylophytes) could be one reason for this inaccuracy².

References

1. Lachin JM (2004) Clin Trials 1: 553

2. Aubin CE et al. (2011) Spine 36: E780

3. Covino SW et al. (1996) J Oral Maxillofac Surg 54: 982

P216 - A Novel Radiographic Assessment Of Optimal Cranio-Cervical Position: The Mandible-C2 Angle With Implications On Occipitocervical Alignment

Richard Bransford¹, Farhan Karim¹, Carlo Bellabarba¹

¹Department of Orthopaedics, Harborview Medical Center, Seattle - United States

Introduction: Craniocervical instability is challenging to the most experienced of spine surgeons. Fixation and fusion from the occiput to the upper/subaxial cervical spine is the accepted surgical treatment, having been first described by Foerster in 1927. Indications for fixation due to instability include congenital deformity, rheumatoid arthritis, tumor and trauma. Non-neutral fixation of the occiput to the cervical spine can result in a myriad of complications including loss of adequate horizontal gaze, subaxial cervical spine deformity, dysphagia, dysphonia, and myelopathy. As rigid, instrumented internal fixation has become the gold standard for craniocervical instability, the necessity for intraoperative tools to assist in determining adequate alignment is vital. At our institution, we have utilized an intra-operative method assessing the angle between the mandible and the C2 body yet this has not been validated. Our goal was to determine whether in a neutral lateral cervical spine radiograph the angle created by the anterior or posterior C2 body and the anterior or posterior mandible is consistent and reproducible to aid with intraoperative assessment. Material and Methods: After IRB approval was secured, we included in this study 100 neutral lateral cervical spine radiographs from December of 2014 to January of 2017. These were interpreted by our radiologists as having “normal” alignment without evidence of severe degenerative disease, deformity or fractures. The study population consisted of 42 Females and 58 Males. The mean age of the patients was 38.8 years. Standard upright lateral films were taken where the patients’ mouths were closed from two non-operative spine clinics. Measurements were taken by two attending spine surgeons, a spine surgery fellow and one resident to ensure adequate intra-observer reliability. Measurements consisted of a previously validated method looking at the occipital-C2 disc space angle and this was compared to four novel measurements: 1) Anterior C2 body- anterior mandible (AB/AM), 2) anterior C2 body-posterior mandible (AB/PM), 3) posterior C2 body-anterior mandible (PB/AM), and 4) posterior C2 body – posterior mandible (PB/PM). Reliability intraclass correlation coefficients (ICC) were also assessed. Results: When assessing the previously validated occiput – C2 disc angle, the mean was 17.3 degrees ± 7.4 degrees. This contrasted with AB/AM of -2.5 degrees ± 6.9 degrees, AB/PM of -2.5 ± 6.9 degrees, PB/AM 4.3 degrees ± 6.7 degrees and PB/PM of 4.5 ± 6.3 degrees. ICCs between the four observers were .889 for Occ-C2, AB/AM of .795, AB/PM of .750, PB/AM of .859, and PB/PM of .876. Conclusion: When assessing the angles between the mandible and the C2 body (whether using anterior or posterior measures), results were equally reproducible as using the validated method of using the occiput and the C2 disc angle. The mandible and C2 body are much easier to assess intra-operatively, and these angles can serve as an excellent tool to help with fusions of the cranio-cervical junction into a physiologic position. This study shows that the angles between the mandible and the C2 body are reproducible and have minimal variation.

P217 - How To Prevent Wrong Level Spine Surgery; A Single Center Experience

Christian Fisahn¹, Cameron Schmidt¹, Emre Yilmaz¹, Daniel di Lorenzo¹, Doniel Drazin¹, Jens Chapman¹

¹Swedish Neuroscience Institute, Swedish Medical Center, Seattle - United States

Introduction: Wrong level operations are unique to spine surgery, often resulting in negative outcomes for both patient and surgeon. The purpose of the survey is to determine what factors are deemed the most important in preventing wrong site spine surgery amongst spine faculty and trainees. Our intention is to catalyze discussion on the most effective means and protocols to prevent wrong level surgery. Materials and Methods: A survey was created that included one question to assess consensus on the single greatest factor contributing to wrong-site surgery; nine yes-no questions to assess opinions on the utility of various methods to reduce wrong-site surgery; and one question rank ordering the importance of various methods for reducing wrong-site surgery. The survey was disseminated between February and May 2017 to spine surgery faculty and trainees. Descriptive statistics were used to characterize the responses. Proportions were calculated and stratified by faculty and trainees for the first 10 questions. For the last question, we used the midpoint of 5 on a 1 to 9 scale to determine the most helpful measures for reducing wrong site surgery as judged by faculty and trainees. Those measures that had a mean rank less than 5 were considered most helpful and those with a mean rank higher than the rank of 5 were considered least helpful. Results: Thirty questionnaires (fellows n = 16; faculty n = 14) were completed and returned to the investigators. A thoracic spine lesion without osseous landmarks was the single greatest factor in wrong-site surgery for the faculty (46.7%) and the trainees (66.7%). Overall classified, as the most helpful tool was a “more concise side specific consent language” in 93.3%. A “routine use of CT to include C7 and L1 in addition to MRI for thoracic soft tissue lesions”, a “radiologists flagging readings on spine for segmentation anomalies” and use of a “level labeled CT scan following myelograms” was classified as “helpful” in 93.3% by the trainees. The most helpful measure for reducing wrong site surgery as judged by faculty was an “intraoperative 3D CT fluoroscopy” (2.6 ± 1.9) and a “routine expanded CT for thoracic spine surgery” (3.4 ± 2.1) as judged by the fellows. As least “helpful” classified by the fellows was a “post-operative marked fluoroscopy” (7.1 ± 2.3). Conclusions: This study could show that faculty and trainess have a different sort of assessment in how to prevent a wrong level surgery. Neverless, both found routine expanded CT, a labeled CT and a more concise side specific consent language to be the effective tools. Intraoperative imaging may be particularly challenging with patients who have decreased bone density or are clinically obese. Especially in thoracic spine lesion without osseous landmarks extreme caution is necessary to prevent wrong level surgery.

P218 - Bone Mineral Density Changes Over Time In Diffuse Idiopathic Skeletal Hyperostosis Of The Thoracic Spine

Jonneke Kuperus¹, Lima Samsoer¹, Stan Buckens², Cumhur Oner¹, Pim de Jong², Jorrit-Jan Verlaan¹

¹Department of Orthopedics, University Medical Center, Utrecht - Netherlands ²Department of Radiology, University Medical Center, Utrecht - Netherlands

Introduction: Diffuse idiopathic skeletal hyperostosis (DISH) is an increasingly prevalent ankylosing condition that confers an increased risk of spinal fractures hypothetically as a result of biomechanical changes of the spine. The aim of this study was to analyze if biomechanical stress-shielding occurs in subjects with DISH by longitudinally measuring bone mineral density (BMD) in the vertebral body of subjects with and without DISH, and in the newly formed bone in subjects with DISH. Materials and Methods: Chest computed tomography (CT) scans of male subjects aged > 50 with two scans with an interval of at least 2.5 years were selected after approval by the medical ethical committee. The first and last CT scan of each subject was evaluated for the presence of DISH using the Resnick criteria. This resulted in a group with pre-DISH (no DISH at the first scan, DISH at the last scan), a group with definite DISH (DISH at both the first and last scan) and a control group. Mean Hounsfield units (HU) were measured in the new bone formation (if present) and in the anterior part and posterior part of the upper vertebral body (1/3 of the vertebral body, above the endplate). The HU values were collected in all levels of the control group and in the most cranial, middle and most caudal levels with DISH. To serve as internal control the HU values were measured in the vertebral body two levels above and below the bridging hyperostosis in the groups with DISH. The paired samples t-test and the independent samples t-test were used after careful assessment of the distribution of the data. Results: The BMD in the new bone formation significantly increased (mean ΔHU 137.5, p-values<0.01) during a mean interval of 5 years at the cranial, middle and caudally involved vertebral segments for both DISH (pre- and definite) groups. The BMD of the vertebral bodies included in the ankylotic segments in the DISH group did not significantly differ from the non-ankylotic vertebral bodies in the same subject. In contrast to our hypothesis, the vertebral body HU value decreased more in the control group compared to the groups with DISH, however statistical significance was reached at one level only (p = 0.048). Conclusions: The new bone bridges in subjects with (pre-) DISH showed increasing BMD over time. However, our data suggests that vertebral BMD is not influenced by the presence of DISH. It can be hypothesized that increased spinal stiffness may be a more important factor than vertebral BMD when explaining the increased fracture risk and typical fracture patterns observed in individuals with DISH.

P219 - Imaging Study Of Basilar Invagination And Atlantoaxial Dislocation

Zhiyuan Xia¹, Zan Chen¹, Wanru Duan¹, Xinghua Zhao¹

¹Department of neurosurgery, XuanWu Hospital, Capital Medical University, Beijing - China

Introduction: To analyze and evaluate new parameters of odontoid process deformity, to investigate the association among atlantoaxial lateral joint deformity, odontoid deformity and atlantoaxial dislocation (AAD) in the patients with basilar invagination (BI), and to analyze the biomechanical mechanism of the patients with BI leading to AAD. Method: Seventy-six patients were divided into three groups. Group A was a normal control group, numbering 23 cases. Group B contained BI patients who were not AAD patients, numbering 21 cases. Group C contained BI patients who were also AAD patients, numbering 32 cases. CT data and 3D reconstruction were collected. We measured the distance from the tip of the dens to the Chamberlain line in the sagittal plane, atlanto-dental interval (ADI), sagittal joint tilt, craniocervical tilt, height of the odontoid and the ratio of the height to the basal width of the odontoid. We statistically analysed the correlation among the groups. Result: The heights of the odontoid process in Groups A, B and C was, respectively,13.38 ± 1.50 mm,10.87 ± 1.48 mm and 8.49 ± 2.49 mm. The ratio of the height to the basal width of the odontoid in Groups A, B and C was 1.32 ± 0.21, 0.91 ± 0.21 and 0.65 ± 0.17. The sagittal joint tilt in Groups A, B and C was 85.85 ± 4.55°,105.76 ± 10.72° and 123.48 ± 12.43°.The craniocervical tilt in Groups A, B and C was 60.31 ± 6.98°, 84.53 ± 18.94° and 71.79 ± 11.69°. The height of the odontoid, the ratio of the height to the basal width of the odontoid, and the sagittal joint tilt were significantly correlated with both BI and AAD (p < 0.001). Odontoid height and height/basal width were significantly correlated with the sagittal joint tilt (p < 0.001). Craniocervical tilt was significantly correlated with BI (p < 0.001). Conclusion: The study proved that the severity of the deformity of the lateral joint and odontoid was significantly correlated with atlanto-axial dislocation and basilar invagination, indicating that deformity of the lateral joint and odontoid process in basilar invagination patients is an important factor causing atlantoaxial dislocation.

P220 - Does the True AP Radiograph for Scoliosis differ from Convention? Lessons from 3D Imaging

Woojin Cho¹, Sandip P. Tarpada², Matthew T. Morris²

¹Department of Orthopaedic Surgery, Albert Einstein College of Medicine / Montefiore Medical Center, Bronx, NY - United States ²Albert Einstein College of Medicine, Bronx, NY - United States

Introduction: Scoliosis has long been measured in the 2D AP plane using the Cobb angle, which does not account for axial vertebral rotation (VR). In the past, the Stagnara lateral has been used in attempt to correct for VR. To date, no similar view has been described for the AP plane. 3D CT imaging may allow for more accurate measurement of Cobb angles by compensating for axial VR. We hypothesized that Cobb angles obtained from the rotationally compensated images differ significantly from those on traditional AP radiograph. Methods: In this retrospective study, standard AP, lateral, and bending radiographs of 23 patients age 10-17 with AIS were obtained. Using multi-planar 3D CT, the coronal plane was reconstructed within the plane of the vertebral axis to form a rotationally compensated 3D CT image (RC-3DCT). The following measurements were made on both imaging modalities: PT, MT, TL/L curve, coronal balance, T/L-AVT, T/L-AVR, thoracic kyphosis, and sagittal balance. Results: The mean MT curve was found to be 52.50° on AP radiograph vs. 45.36° on RC-3DCT (P = 0.011). In 3 patients (13.04%), rotational compensation altered the end vertebra of the major curve by at least 1 level. The mean TL curve obtained on radiograph, was significantly larger than that of RC-3DCT (42.93 vs. 34.32°; P = 0.00 210). AP films overstated coronal balance by over 50% when compared to RC-3DCT (P = 0.0320). Mean T-AVT was measured to be 37.04 mm on conventional films and 29.8 mm on RC-3DCT (P = 0.028). RC-3DCT L-AVT was significantly smaller than that of standard films (P = 0.034). Mean T-AVR on standing film was 18.9 ± 11.2°. The mean thoracic kyphosis greatly differed between the two modalities: 33.69°on radiograph vs. 20.04° on RC-3DCT (P = 2.16x10^-5 ). Conclusions: Measurements traditionally made on AP radiograph to evaluate scoliosis may be fundamentally inaccurate due to VR. Our data suggests that axial rotation of a patient 19° per Nash–Moe grade with respect to the coronal plane may adequately compensate for the rotational component of deformity without the need for CT. Additionally, rotational compensation may yield end vertebrae levels different from those obtained traditionally.

P221 - Hyperthermia Associated With Spinal Radiculopathy As Determined By Digital Infrared Thermographic Imaging

Tae Kyoo Lim¹, Seung Son¹, Sang Gu Lee¹, Woo Kyung Kim¹

¹Department of Neurosurgery, Gachon Gil Medical Center, Incheon - Korea, Republic

Introduction: Spinal unilateral radiculopathy is normally considered to be associated with hypothermia as determined by digital infrared thermographic imaging (DITI). However, DITI sometimes reveals hyperthermia in the pain-affected ipsilateral dermatome. This study analyzed the prevalence of hyperthermia in patients with spinal radiculopathy, and compared the characteristics of these patients. Material and Methods: Among 770 patients that underwent DITI from 2014 to 2016, 252 patients with unilateral spinal radiculopathy were enrolled finally. Relations between DITI determined hyperthermia and pathology site, demographic data, symptoms, and pathology level were investigated. Results: Patients’ baseline characteristics were non-significantly different in the hypothermia (n = 221) and hyperthermia (n = 31) groups. Radiculopathy in the hyperthermia group was significantly more prevalent in the cervical spine than in the lumbar spine (p = 0.011). Both groups were similar with respect to the degree of pain using visual analogue scale and symptom duration, but hyperthermia group had significantly more motor weakness (p = 0.008). Conclusion: The presence of hyperthermia is valued at 12.3% of spinal unilateral radiculopathy patients, especially in patients with cervical spinal radiculopathy or severe nerve root entrapment represented by motor weakness. Therefore, if DITI demonstrates the hyperthermia in pathologic side, the examiner should not be confused in diagnosis and treatment.

P222 - Whole Spine Magnetic Resonance Imaging Findings Are Highly Sensitive In The Diagnosis Of Spinal Tuberculosis

Ajoy Shetty¹, Rishi Mugesh Kanna², Anupama Maheswaran³, Pushpa Bhari⁴, S Rajasekaran⁵

¹Senior Spine Consultant, Dept of Orthopaedics, Ganga Hospital, Coimbatore - India ²Associate Consultant, Dept of Orthopaedics, Ganga Hospital, Coimbatore - India ³Consultant, Dept of Radiology, Ganga Hospital, Coimbatore - India ⁴Junior Consultant, Dept of Radiology, Ganga Hospital, Coimbatore - India ⁵Chairman, Dept of Orthopaedics, Trauma & Spine Surgery, Ganga Hospital, Coimbatore - India

Introduction: Tubercular (TB) culture and histopathological evidence are considered as gold standard tests to confirm the diagnosis of spinal tuberculosis. The diagnostic utility of whole spine MRI findings has not been analysed in comparison to tissue studies. Materials and Methods: We prospectively studied 68 consecutive patients with spondylodiscitis. All patients had MRI of the whole spine and biopsy for tissue GeneXpert test, histopathological examination (HPE) & tuberculous culture. Based on the results, patients were divided into two groups - confirmed TB (Group A) with positive tubercular culture and or positive HPE for tuberculosis and non-TB (Group B), when both culture and HPE were negative. Positive HPE for TB was based on presence of epitheloid granulomas and multi-nucleated giant cells. MRI features considered characteristic of TB included multi-level lesion (> 3 vertebra - contiguous and non-contiguous), intra-osseous abscess and extensive abscess formation (multi-loculated, long segment abscess, circumferential abscess) and bilateral psoas abscess. The sensitivity, specificity, predictive value of MRI findings and GeneXpert test was studied between the two groups. Results: The mean age of the patients was 48.6 ± 18.3 years with a male: female distribution of 29:39. In 22 patients, the lesion was at thoracic spine (T1-T11); 19 patients had affliction at thoraco-lumbar region (T12-L1); 18 in the lumbar and sacral region and 9 in the other regions of the spine. Fifty two patients underwent surgical treatment and the remaining 16 had been treated non-operatively. Among 68 patients, 49 had confirmed TB (Group A) (23 by positive TB culture, 26 by positive HPE and 14 with both culture and HPE positive). The remaining Group B had 19 patients, including 8 pyogenic infections, 3 pathological fracture, and 8 inconclusive reports. The GeneXpert was positive in 39 cases (31 in group A and 8 in Group B) with a sensitivity of 63%, specificity of 58%, positive predictive value of 79% and negative predictive value of 38%. MRI was positive in 50 patients (42 in group A and 8 in Group B) with a sensitivity of 85%, specificity of 58%, PPV of 84% and NPV of 61%. MRI features diagnostic of tuberculosis included a combination of extensive abscess formation (n = 42), intraosseous abscess (n = 9), Multi-level lesions (n = 25) and psoas abscess (n = 23). All group A patients showed good healing of the lesion at the completion of anti-tubercular chemotherapy and there were no cases of treatment failure or relapse within a one year follow-up period. Among the 39 patients with positive GeneXpertest, all showed sensitivity to Rifampicin except 2 patients. Conclusion: MRI plays an important role in the diagnosis of spinal TB similar to chest radiograph for pulmonary TB, but often under appreciated. We observed that whole spine MRI findings including multi-level skipped lesions, extensive abscess formation, and bilateral psoas abscess had very good sensitivity (85%) to diagnose tuberculosis while GeneXpert test had only moderate sensitivity and specificity. Thus MRI findings in combination with tissue examination (HPE, culture and GeneXpert test) are important elements for diagnosing spinal TB.

P223 - Radiographic Study Of Iliac Height And Transverse Process Related To Degenerative Spondylolisthesis L4-L5

Thiago Maia¹, Charbel Jacob Jr¹, Igor Machado Cardoso¹, José Lucas Batista Jr¹, Marcus Alexandre Novo Brazolino¹, Rafael Poubel Bolelli de Rezende¹, Ronaldo Roncetti Junior¹

¹Department of Orthopedics, Santa Casa de Vitoria, Vitoria - Brazil

Introduction: Degenerative spondylolisthesis (DS) consists of the vertebral slip caused by anatomical changes associated with the disc disease, among which, the positioning of the articular facets, the height of the iliac crests and the sacralization of L5, can cause a mechanical overload at the L4- L5, which contributes to the vertebral slip with the integrity of the neural arch. Materials and Methods: The length and width of the transverse process of L3-L4-L5, as well as the height of the iliac crests, were analyzed in antero-posterior radiographs and profile of 31 patients diagnosed with degenerative spondylolisthesis according to Wiltse, Newman and Macnab classification. Measurements were made using the Osirix application with the pixel format. In relation to the measurement of the iliac we used the criteria of Hosoe and Ohmori, which considers the height of the iliac disc level L4-L5 as the normal anatomical pattern. Results: Of the 31 patients with L4-L5 DS, 21 were female. The mean transverse process width of L3-L4-L5 was 89.1, 83.5 and 98.1 pixels, respectively, the mean transverse process length being L3, L4, and L5, 281.6, 254.2 and 278.6 pixels, respectively. Regarding the height of the iliac crest, 58.06% of the patients presented measurements above the L4-L5 disc space, being considered high according to Hosoe and Ohmori criteria. Conclusions: In the L4-L5 DS patients, the width and length of L4 were lower in relation to L3 and L5, and the height of the iliac crest was elevated in most patients.

P224 - Knowledge And Attitude Of Spine Surgeons Regarding Radiation Exposure

Asdrubal Falavigna¹, Alexandre Iutaka², Miguel Bertelli Ramos³, Cristiano Magalhães Menezes⁴, Nestor Taboada⁵

¹University of Caxias do Sul - Brazil ²Hospital Israelita Albert Einstein, São Paulo - Brazil ³Laboratory of Clinical Studies and Basic Models on Spinal Cord Pathologies, University of Caxias do Sul - Brazil ⁴Hospital Da Baleia, Belo Horizonte - Brazil ⁵UNIMEC, Barranquilla - Colombia

Introduction: Questionnaires evaluating spine surgeons’ knowledge and attitude regarding radiation exposure are scarce in literature. Spine surgeons are exposed to high amounts of radiation from fluoroscopy procedures throughout their lifetime. Good practices may minimize this exposure, requiring prior knowledge of radiation basics and their application in a spine surgery scenario. This project aims to evaluate spine surgeons’ perceptions and attitudes regarding radiation exposure during spine surgery. Material and Methods: A questionnaire for spine surgeons was elaborated comprising questions on general information and surgeons’ perceptions and attitudes regarding radiation exposure during spine surgery. Questions were sent via Survey Monkey tool to spine surgeons who were members of AOSpine Latin America, during the period between December 15th 2016 and January 15th 2017. The answers from countries that had more than 40 surgeons were compared. Continuous variables were described using mean and standard deviation. Categorical data were presented as counts and percentages. Comparisons were conducted using Fisher’s exact test. Post-hoc comparisons were adjusted by Bonferroni procedure. Significance level was set at p < 0.05. Data were processed and analysed using SPSS version 22.0. Results: The questionnaire was answered by 371 surgeons. There were more orthopaedic surgeons (n = 212) than neurosurgeons (n = 159). Most surgeons (54.2%) were very experienced. Thyroid protector was not used by 238 surgeons (35.8%). Lead glasses were used by 75 (20.2%) and lead gloves by 26 (7%). The dosimeter badge was never or rarely used by 281 (75.7%) and 321 (86.5%) don’t know their own dose limits. Only 124 surgeons (33.4%) answered that staying on the image intensifier side during lateral lumbar fluoroscopy reduces the surgeon’s exposure. Orthopaedic surgeons answered the best position of the surgeon during lateral lumbar fluoroscopy correctly more often than neurosurgeons (p = 0.01). Usage of thyroid shield, staying behind the X-ray source and usage of navigation were greater among neurosurgeons than among orthopaedic surgeons, p = 0.005, p = 0.006 and p < 0.001, respectively. Staying behind the X-ray source and usage of navigation were also greater among more experienced surgeons than among less experienced ones, respectively, p = 0.01 and p = 0.005. Surgeons from Brazil and Colombia reported greater use of the thyroid protector than surgeons from Mexico and Argentina (p < 0.001). Stepping back during fluoroscopy was also significantly greater in the former than in the latter (p = 0.01). However, pulsed-mode fluoroscopy is significantly more used in Mexico and Argentina when compared to Brazil and Colombia (p < 0.0001). Conclusion: Spine surgeons do not know sufficient or take a proactive attitude towards radiation exposure.

P225 - Intraoperative Computed Tomography In Spine Surgery: What Have We Done And Learned In 5 Years?

Juan José Zamorano¹, Bartolome Marré¹, Alvaro Silva¹, Ratko Yurac¹, Cesar Gaete¹, Felipe Novoa¹, Manuel Valencia¹, Guillermo Izquierdo¹, Matías Delgado¹

¹Clinica Alemana - UDD, Santiago - Chile

Introduction: Intraoperative computed tomography (IO-TC) and computer-assisted surgery (or neuronavigation, NV) have been progressively adopted by spine surgeons worldwide. These technologies allow us to improve accuracy of implant insertion and/or tumor resection. Their use has been associated with a higher security of traditional surgical techniques, but has also allowed the development of new, less invasive procedures, reducing both their duration as well as the radiation to which all the participants are exposed. Intraoperative computed tomography on its own (without neuronavigation) is also an attractive alternative, as it permits a precise intraoperative assessment of the performed procedure before closure: implant position, fracture reduction, extent of decompression and/or tumor resection. We present our experience with the use of IO-TC with or without NV in spine surgery at a single center in Chile, South America. Materials and Methods: We reviewed our institutional patient database to identify patients operated for spine conditions by members of the Spine Unit using IO-TC with or without NV, to describe the use we have given to these technologies since their implementation at our institution and what we have learned from it. Results: We identified 245 patients operated with IO-TC with or without NV between May 2012 and May 2017: 51 patients (20.8%) during the first 18 months and 108 patients (44.1%) during the last 18 months. In 167 patients (68.2%) an IO-TC was obtained as an intraoperative control to assess the performed surgery before closure (150 of these patients had a spine fusion), in 43 patients (17.6%) the IO-TC equipment was only used in fluoroscopy mode for percutaneous procedures (33 patients had vertebral cement augmentation and 10 patients had isolated vertebral or intervertebral disc biopsies performed). The remaining 35 patients (14.3%) were operated using IO-TC with neuronavigation. When we analyzed how the use of these technologies has evolved since its implementation at our institution, we noticed that most of the cases involving neuronavigation (30/35, 85.7%) were performed during the first 16 months (early stage), with a progressive decline in its use afterwards. On the other hand, both the fluoroscopy-only mode and the IO-TC as an intraoperative control before closure have shown a progressive increase in their use over the years. During the last 12 months, we used these technologies in 79 patients, 22.9% of them with fluoroscopy-only mode and 72.2% for pre-closure IO-TC, which has become the main indication we are currently using this equipment for. Conclusion: Since its implementation at our institution, five years ago, we can conclude that intraoperative computed tomography (mainly without neuronavigation) has been successfully incorporated as technologic advance to increase our patients’ safety in the operating room. The pre-closure IO-TC has become almost a routine procedure for our instrumented and tumor cases.

P226 - Does Multilevel Lumbar Stenosis relate to Poorer Clinical Outcomes? A Correlation Study of Standing MRI Findings and Multilevel Stenosis Symptoms

Yvonne Yan On Lau¹, Ka Lok Ryan Lee², James Francis Griffith³, Lai Yee Carol Chan¹, Sheung Wai Law¹, Kin On Kwok¹

¹Department of Orthopaedics & Traumatology, The Chinese University of Hong Kong, Hong Kong - Hong Kong ²Prince of Wales Hospital, Hong Kong - Hong Kong ³Department of Imaging and Interventional Radiology, The Chinese University of Hong Kong - Hong Kong

Introduction: Lumbar spinal stenosis has shown improved clinical correlation with findings of standing MRI. However, the impact of multilevel stenosis was unknown. We assessed the relationship between clinical features, dural sac cross sectional area (DSCA) and multilevel stenosis in this prospective study. Methods: This study is a subanalysis of the previous clinical correlation study of standing MRI in 70 lumbar spinal stenosis patients. Sixty-eight patients with neurogenic claudication were included to undergo a 0.25-T MRI exam performed in supine and standing positions. Clinical features including BMI, duration, walking distance, leg pain VAS, Chinese Owestry Disability Index (CODI) and SF-12 were assessed. DSCA of the most constricted and the next stenotic levels were measured and correlated with each feature by Pearson and Spearman correlation coefficients(r). The number of stenosis levels with DSCA ≤ 75 mm² and the presence of spondylolisthesis were studied. Results: Standing MRI diagnosed 22% more cases of multilevel stenosis than supine MRI. Dynamic narrowing of dural sac on standing happened in multilevel stenosis as in overall spinal stenosis (r = 0.88, p < 0.0001). DSCA at the most constricted level was smaller on standing MRI than on supine MRI (r = 0.79, p < 0.0001). This is also true the next stenotic level (r = 0.69, p < 0.0001). Shorter walking distance correlated with smaller DSCA in either single-level stenosis (r = 0.44, p = 0.005) or multilevel stenosis (r = 0.45, p = 0.014). The minimal DSCA associated with BMI (r = -0.44, p = 0.018) and duration of symptom (r = -0.41, p = 0.027) only in multilevel stenosis patients. Smaller DSCA in the next stenotic level correlated with worse leg pain (r = -0.41, p = 0.027). Patients with multilevel stenosis showed less disability(r = -0.27, p = 0.025) despite having smaller DSCA than patients with single-level stenosis (p < 0.0001). Conclusion: Standing MRI is efficient to uncover multilevel stenosis with limited walking ability as single-level stenosis. The significant correlations of BMI, duration and less functional disability with multilevel stenosis reflect the dural-sac adaptation capability for chronic compression. Since the next stenotic level associated with radicular leg pain, better-defined diagnosis of multilevel stenosis influences surgical decision and outcome.

P227 - Evaluation Of Network Efficiency In Spinal Cord Injury Using Graph Theoretical Analysis Of The Brain In The Resting-State

Mayank Kaushal¹, Akinwunmi Oni-Orisan², Gang Chen³, Wenjun Li³, Jack Leschke⁴, Benjamin Kalinosky⁵, Matthew Budde¹, Brian Schmit⁵, Shi-Jiang Li³, Vaishnavi Muqeet⁶, Shekar Kurpad¹

¹Department of Neurosurgery, Medical College of Wisconsin, Milwaukee - United States ²Department of Neurosurgery, UT Health Science Center at Houston, Houston - United States ³Department of Biophysics, Medical College of Wisconsin, Milwaukee - United States ⁴Department of Neurosurgery, University of Minnesota, Minneapolis - United States ⁵Department of Biomedical Engineering, Marquette University, Milwaukee - United States ⁶Department of Physical Medicine and Rehabilitation, Medical College of Wisconsin, Milwaukee - United States

Introduction: Graph theory deconstructs the resting-state functional MRI (rs-fMRI) datasets into “nodes” and “edges” for calculating quantifiable network metrics, which are compared between clinical populations of interest and controls to evaluate dysfunction in global and local brain networks. The present study used graph theory for highlighting the changes to the intrinsic connectivity of the whole brain network in patients with spinal cord injury (SCI). Material and Methods: After obtaining IRB approval, 15 subjects with chronic, complete cervical SCI and 15 controls were scanned. The raw imaging data was preprocessed followed by parcellation of the entire brain into 264 regions of interest (ROIs). Correlation analysis was performed between every pair of ROIs to construct connection matrices. Subsequently, local efficiency (LE) and global efficiency (GE) were calculated at incremental cost thresholds (% of total possible connections) and compared between the study groups. Results: The whole brain network showed significant differences between the two study groups at multiple cost thresholds for the network metrics of GE and LE, that measure the ability of a network to transmit information at the global and the local level, respectively (p value < 0.05). The GE metric, used to evaluate the network property of integration was significantly increased in SCI. The LE metric, representing network segregation, showed significant reduction in the SCI group compared to controls. Conclusion: The differences in quantitative metrics characterizing network attributes of integration and segregation demonstrates the applicability of graph theory in studying the resting-state networks in neurosurgical patient populations. The findings illustrate that brain undergoes reorganization following SCI due to inherent neural plasticity, which is associated with alterations to information transmission within and between brain regions. The information derived from the network metrics regarding the functional alterations has the potential to identify imaging biomarkers for improving prognostication after SCI. In addition, quantitative network metrics could help in the development of personalized therapeutic strategies involving the use of brain-computer interface by offering a mechanism for the measurement of functional outcomes.

P228 - The Entry Point And Angulation In The Placement Of The Cage In Olif L2-L5: A Ct-Based Study In The Korean Population

Javier Quillo-Olvera¹, Guang-Xun Lin¹, Jin-Sung Kim¹

¹Seoul, St. Mary's Hospital, Spine Center, Department of Neurosurgery, The Catholic University of Korea, Seoul - Korea, Republic

Introduction: Several studies have described the anatomical characteristics of OLIF surgical corridor. However, the entry point through the intervertebral disc and the angle for placing the cage have not yet been studied. We reported both data in this study. Material and Methods: Ninety non-enhanced lumbar spine CT scans were revised from May 2017 to August 2017 randomly. Ten CT scans were excluded for previous lumbar surgery. In the remaining eighty CT studies, the following measurements were analyzed in axial views at the L2-L5 levels: The anteroposterior axis in the sagittal midplane divided into thirds. The distance between the anterior vertebral line (AVL) and the left anterolateral border of the middle third of the vertebral body defined as the entry point (EP). The distance between the lateral edge of the aorta / iliac artery and the EP (AV-EP). The entry point angle (EPA) formed between the EP and the contralateral point where the middle and the posterior third of the vertebral body join. The cross-sectional area of the left psoas muscle from its anterior border to the middle-posterior third junction of the vertebral body defined as total retraction of the psoas muscle. The angle formed by the tangential line to the anterior belly of the left psoas muscle and the coronal midplane defined as the common surgical corridor angle (CSCA). The age, sex, and body mass index (BMI) of each patient were acquired. Descriptive statistics of the results expressed as mean and standard deviation (SD), and “t” test for comparing the differences between variables were reported. Multiple linear regression analysis was used to determine the influence of demographic data and measurements on the EP at each level from L2-L5. Results: Measurements of 80 CT scans on axial view (46 males and 34 females with a mean age of 43.6 ± 12.4 years, and a mean BMI of 24.92 ± 3.01) were analyzed at each level from L2-L5. The mean CSCA for L2-L3 was 44.1º ± 6.9, L3-L4 44.9º ± 7.7, and L4-L5 46.8º ± 8.1. The mean EPA for L2-L3 was 16.8º ± 1.1, L3-L4 15.9º ± 1.1, and L4-L5 15.1º ± 0.89. The mean distances from AVL-EP on L2-L3, L3-L4, and L4-L5 were 12.1 mm ± 0.9, 12.2 mm ± 0.8, and 12.4 mm ± 1.2 respectively. The mean distance from AV-EP on L2-L3, L3-L4, and L4-L5 were 15.6 mm ± 5.1, 17.3 mm ± 4.5, and 14.5 mm ± 6.1 respectively. The percentage of psoas retraction associated with EPA on L2-L3 was 20.78%, L3-L4 28.09%, and L4-L5 43.18%. Sex, age and AV-EP distance had influence on the EP on L2-L3 (r²: 0.437, p < 0.001) L3-L4 (r²: 0.376, p < 0.001) and L4-L5 (r²: 0.219, p < 0.001) on the multiple linear regression analysis. Conclusion: With the EPA reported in this study the cage can be placed in the middle third of the vertebral body with a minimal risk of neural elements injury. The mean distance between the anterior lumbar vessel and the EP was 12.25 mm. Therefore, there is a lower risk of vascular injury.

P229 - Navigation In Deformity Surgery Helps To Reduce Intraoperative Spinal Cord Monitoring Events

Lui Darren¹, Sara Khoyratty¹, Adam Benton¹, Hai Ming Yu¹, Susanne Selvadurai¹, Sean Molloy¹

¹Royal National Orthopaedic Hospital, London - United Kingdom

Introduction: Intra operative navigation (O-Arm®) allows 3 dimensional real time assessment and has many documented benefits including lower radiation dose to the surgeon and assistant, more accurate pedicle or lateral mass screw placement and ability to aid minimally invasive surgery. Utilisation of the O-Arm allows accurate and precise single pass screw insertion and mitigates multiple pedicle passes (e.g. finder and feeler, tapping and feeler, screw removal for tract checking). It can also be adapted to aid ultrasonic bone cutter use for osteotomies. To our knowledge O-Arm has not been investigated for adult posterior spinal surgery with spinal cord monitoring. Spinal cord monitoring (SCM) is an essential tool in the spine surgery armamentarium. Warnings by the neurophysiologist can mitigate neural injury. We hypothesize that O-Arm® intraoperative navigation helps to mitigate spinal cord monitoring events by allowing a single pass pedicle screw insertion technique Materials and Methods: Retrospective study Between 2005-2015, a single surgeon in two centres was analysed for adult posterior spinal surgical cases. We divided the cases by those prior to O-Arm use and those cases where O-Arm was utilised. Spinal cord monitoring included somatosensory evoked potentials (SSEP) and motor evoked potentials (MEP). Events were categorised as Green (No events), Amber (Events occurred but Resolved), Red (Events occurred and did not resolve during operation) and Black (Technical difficulty). Results: 669 consecutive adult posterior spinal surgical cases were identified. Age and sex were well matched (57y v 59y). Pre O-Arm approximately over 5 years: 355 (53%) cases had 10.3% SCM events (Green 89.2%, Amber 6.4%, Red 3.9%, Black 0.002%). Utilising the O-Arm in approximately 5 years: 314 (47%) cases had 6.3% SCM events (Green 86.2%, Amber 2.8%, Red 3.5%). Conclusion: Mitigating neurological injury in the perioperative period is of high importance in adult posterior spinal surgery. The Scoli-RISK-1 study showed a 26.2% perioperative neurological deterioration in the first 6 weeks following surgery. The O-arm intraoperative navigation has allowed the development of accurate and precise single pass pedicle screw insertion and to guide osteotomies with an ultrasonic bone cutter. Utilising a dedicated neurophysiology team there is a decrease from 10.3% spinal cord monitoring events to 6.3% with O-Arm use. Spinal cord monitoring in addition to O-Arm use is an excellent addition to the spine surgeon’s armamentarium.

Infections

P230 - Independent Predictors For The Development Of Focal Kyphosis And The Effects On Patients With Spinal Epidural Abscess

Huiliang Yang¹, Akash A. Shah², Gi Hye Im², Yueming Song¹, Joseph H. Schwab²

¹Department of Orthopaedics, Sichuan University, Chengdu - China ²Department of Orthopaedic Surgery, Harvard University, Boston - United States

Introduction: While rare, spinal epidural abscess (SEA) is associated with significant morbidity and mortality. In addition to the potentially catastrophic neurologic deficits incurred from this disease process, SEA may also lead to bone destruction resulting in focal kyphosis of the affected spinal segments. Focal kyphosis can cause neurologic deficit and instability of the spine, resulting in the need for emergency spinal cord decompression and spine fixation. The incidence of spinal focal kyphosis and risk factors associated with its development are not well characterized in the literature. Material and Methods: We conducted a retrospective cohort study using electronic records in our hospital system. All patients were over 18 years old and had a clinically and radiologically documented SEA during the period 1993-2016. When prior spinal imaging was available, we identified obvious focal kyphosis by a change from the baseline radiological studies. When prior spinal imaging was not available, we identified the focal kyphosis through radiological reports and other electronic records. Meanwhile, Cobb angle change should be more than 5°, Cobb angle change = middle Cobb angle – (superior Cobb angle + inferior Cobb angle)/2. We analyzed the risk factors for the development of focal kyphosis through univariate and stepwise multivariate logistic regression. We made a nomogram to predict focal kyphosis based on final multivariate model. We analyzed the association of focal kyphosis with patients’ symptom at presentation, treatment, and outcomes using univariate logistic regression. Results: The study included 1,053 patients with SEA, 108 of whom developed obvious focal kyphosis. Six predictors for predicting focal kyphosis were found, including 5 risk factors and 1 protective factor. Risk factors consisted of low bone density in the past year (p < 0.001), symptom duration > 2 weeks (p = 0.024), vertebral osteomyelitis (p < 0.003), spondylodiscitis (p < 0.001), and the involved region of the spine, in reference to the lumbar/sacral region (cervical, p < 0001; cervicothoracic, p = 0.004; thoracic, p < 0.001; thoracolumbar, p < 0.001; multifocal/>2 contiguous regions, p = 0.040). The protective factor was spinal osteoarthritis (p = 0.004). The nomogram was made based on the final multivariate model. Focal kyphosis was significantly associated with motor deficit at presentation (p < 0.001), surgery (p = 0.001), even instrumentation (p < 0.001). In addition, focal kyphosis was also significantly associated with residual motor deficit at last follow up (p = 0.002) and failure of initial non-operative treatment (p = 0.003). Focal kyphosis was not significantly associated with 90-day mortality or SEA recurrence. Conclusion: In this cohort of patients, 10% developed focal kyphosis. The loss of bone density in the past year, symptom duration > 2 weeks, vertebral osteomyelitis, spondylodiscitis, and the involved region of the spine were risks factors for the development of focal kyphosis. However, spinal osteoarthritis was a protective factor for focal kyphosis. Focal kyphosis was significantly associated with patients’ neurologic status at admission and residual motor deficit at last follow-up. Moreover, focal kyphosis increased the probability of receiving surgery and even new instrumentation for patients with SEA, as a result of vertebrae compression, spinal cord compression, and spine instability. Our nomogram was user-friendly for clinicians and patients. Our study could help clinicians fully understand the development of focal kyphosis and its effects, thus preventing the development of focal kyphosis in patients with SEA by treating to increase bone density and using an orthosis brace or radical surgery.

P231 - Role Of Magnetic Resonance Imaging In Caries Spine

Waqar Alam¹

¹Department of Orthopedics District Headquarter Hospital Timergara, Timergara - Pakistan

Introduction: Spinal tuberculosis is an ancient disease and the causative agent, Mycobacterium Tuberculosis is still detectable in the bones of Egyptian mummies.¹ The first description of spinal tuberculosis was given by Sir Percival Pott in 1779.² Today Spinal tuberculosis constitutes 50% of skeletal tuberculosis, 50-60% of extra Pulmonary tuberculosis and 1-5% of all tuberculosis cases. It continues to be a fatal disease in developed and under developed countries.³ Although the thoracolumbar junction seems to be the most common site of the spinal ORIGINAL ARTICLE 92 JIMDC 2017 92 column involvement in Caries spine, any part of the spine can be affected.⁴ Furthermore, the incidence of neurologic complications in Caries spine varies from 10% to 43%.⁵ The diagnosis of spinal tuberculosis is not easy and in almost all cases, the illness manifests in advanced stages.⁶ Conventional radiological imaging is noninvasive but it takes nearly three to four months for spinal tuberculous lesion to be evident on plain radiographs and unfortunately, more than 50% of the vertebra are destroyed before the formation of the lesions to be seen on a plain radiograph.^7,8,9 The advent of magnetic resonance imaging (MRI), with reported sensitivity and specificity of 100% and 88.2% respectively, for Caries spine has revolutionized the diagnosis of the condition.¹⁰ It can identify the pathological lesions in the early stages of the disease, correctly demonstrate the extent of the disease involvement and can monitor the response to treatment. However, the usefulness of MRI in diagnosis depends on accurate interpretations of the findings seen. Although the literature outlined the broad-spectrum features of MRI in spinal TB,¹¹ but what exactly defined the tubercular lesion on a spinal MRI is still not mutually agreed.¹¹ Hence, this study was conducted to outline, various pathological changes seen on MRI in established cases of Caries spine and to evaluate its diagnostic accuracy Material and Methods: This cross-sectional study was conducted at Department of Orthopedic and Spine surgery, Ghurki |Trust Teaching Hospital Lahore, from January 2012 to May 2016. Patients who underwent surgery for cervical, thoracic and lumbar spinal tuberculosis were inducted in the study. Their MRI were reviewed and eight parameters namely T1 hypo intensity, T2 hyper intensity, epiphyseal involvement, disc involvement, pedicle involvement, anterior subligamentous extension, paraspinal extension and no spinous process involvements were noted. Each of the variables were given 1 point when present and zero when absent. Score of ≥ 6 favored a tuberculous pathology whereas ≤4 were suggestive of non-tuberculous etiology. Results: We evaluated 243 patients of histopathologically proven cases of caries spine. Among these, 129 (53.08%) were females and 114 (46.91%) were males. Mean age of patients was 39.04 years ranging from 8 years to 71 years. Dorsal spine was mainly involved in 105 (43.21%) patients followed by lumbar spine in 91(37.45%) and cervical spine in 47 (19%) patients. Number of vertebrae involved were two or more in each case. Data showed that 238 (97.94%) patients had score ≥ 6 which favored a tuberculous spine whereas 5 (2.06%) patients had scores 5 which suggest antituberculous cause. Conclusion: Our study revealed that objectively outlined eight-point MRI criteria of vertebral lesions is expected to diagnose caries spine with confidence in majority of cases. The proposed scoring system will mitigate the dependency on histopathological diagnosis or invasive method, so that early initiation of anti-tuberculous therapy may be possible.

P232 - The Treatment Of Delayed Infection After Posterior Instrumented Spinal Surgery

Yan Zeng¹, Woquan Zhong¹

¹Orthopedic Department, Peking University Third Hospital, Beijing - China

Introduction: To analyze the treatment of delayed infection (first onset time more than one month after surgery) after posterior instrumented spinal surgery. Material and Methods: Eighteenpatients of delayed infection after posterior instrumented spinal surgery were treated in our hospital. The surgical procedures were posterior cervicallaminoplastyin one case and posterior lumbar decompression and fusion in 17 cases. There were 9 cases of delayed deep incision infection (group 1), 7 cases of delayed intervertebral space infection (group 2), and 2 cases of delayed deep incision with intervertebral space infection (group 3). The characteristics of delayedinfection among the three groups were analyzed and compared, including the temperature, inflammatory indexes (WBC, ESR, CRP), and clinical findings. The corresponding treatment were performed. Results: The average onsettime of delayed infection was 17 months after surgery (1-101 months). There was no significant difference inthe onset time, temperature, and inflammatory indexes among threegroups (P > 0.05), except for the temperature between group 2 and group 3 (P < 0.05). In group 1, 8 patients underwent reoperation (debridement, washing and drainage), among them 4 cases had the implant removed with definite fusion. In group 2, onlyone case of segmental instability was treated with reoperation. In group 3, one case with severe deep infection also underwentdebridement surgery. Othercases were treated conservatively with antibiotics. All the patients got complete recovery, and no recurrent infection was observed after 18 months (12-40 months) of follow-up. Conclusion: Surgery intervention, including debridement, washing and drainage, is effective to the delayed deep incision infection. It is recommended to remove implant forthe case with solid fusion. Conservative treatment with antibiotics is preferred to simple delayed intervertebral space infection.

P233 - Trends In Spinal Surgery For Pott’s Disease (2000-2016): An Overview And Bibliometric Study

Christian Fisahn¹, Fernando Alonso¹, Ghazwan A. Hasan², R. Shane Tubbs³, Joseph R. Dettori⁴, Thomas A. Schildhauer⁵, Tarush Rustagi Rustagi¹

¹Swedish Neuroscience Institute, Swedish Medical Center, Seattle - United States ²Shaheed Ghazi Al-Hariri Specialized Surgical Hospital, Baghdad - Iraq ³Seattle Science Foundation, Seattle - United States ⁴Spectrum Research, Inc., Tacoma - United States ⁵Department of Trauma Surgery, BG University Hospital Bergmannsheil, Bochum - Germany

Introduction: Tuberculosis affecting the human bones and joints has a long historical background. It is estimated that 2 million people suffer from spinal tuberculosis. The aims of this study are to evaluate the current trends of surgical intervention in Pott’s disease treatment, identify regional differences in the surgical management and identify indication for surgical treatment of the disease. We therefore asked the following questions: (1) What are the surgical indications? Have they changed over time since the year 2000? (2) What is the current surgical approaches of choice? Have they changed over time since the year 2000? Do they vary by geographical region? (3) What are the most common outcome measures following surgery? Material and Methods: Electronic databases and reference lists of key articles were searched from database inception from January 1, 2000 to December 31, 2016 to identify studies specifically evaluating surgical indications, current surgical approaches and outcome measures for spinal tuberculosis. Results: Six randomized controlled trials were identified from our search (one excluded: no surgical arm identified after review) Neurological deficit, instability and deformity were common indications identified. Surgical approach included predominantly anterior for cervical spine and posterior for thoracic and lumbar spine. Combined approach was preferred in pediatric cases. Degree of deformity correction, neurological outcomes and fusion formed main basis of assessing surgical outcomes. Conclusion: Majority of the current literature is from South Asia. The presence of neurological compromise, deformity and instability were the primary criteria for surgical intervention. The preferred approach varied with the anatomical region of the spine in adults. Outcome measures predominantly involved deformity correction, neurological deficit and fusion.

P234 - Post Operative Infections

Carlos Mariano Nirino¹, Carlos Eduardo Nemirovsky¹

¹Department of Orthopedics and Traumatology, CMGSM, BS AS, Buenos Aires - Argentina

Introduction: The aim of this paper is to describe the behaviour used in our department in all cases of post surgical infections and its results. They all were operated in the last 5 years in our department of Orthopedics and Traumatology in Corporación Medica of General San Martin in Buenos Aires, Argentina. All the patients were operated by the same surgeon and same surgical team. In absolutely all cases where we had a post surgical infection, our initial behaviour was the debridement of the tissues and the sending of these for cultivation and antibiogram to the corresponding typing of the germ. After this for the closure of the wound, depending on each particular case, we used the VAC system (vacuum assisted closure), polyurethane sponges with continuous drip, iodoformed gauze, gauze dressing impregnated with nitrofurazone, secondary closures and healing by second. The results were very good because in all cases the wounds closed and healed without any added inconvenience. Materials and Methods: Twenty one patients, 9 men and 12 women, who had post operative infections and had to return to the operating room for treatment, were evaluated. Patients with superficial skin infections, who were treated and cured only with antibiotics, were excluded from this study. All of them were treated by the same surgical team. Surgical technique: It consists in the debridement of the tissues and the sending to cultivation and antibiogram for typing the germ. In absolutely all cases a continuous washing with “polish” solution (solution of hydrogen peroxide with an antiseptic) is carried out. Then we proceed to the placement of iodoformed or impregnated nitrofurazine gauzes. This behaviour is performed in at least 3 or 4 opportunities every 48 or 72 hours until the provision of the VAC system; in case that this system is not provided we use a polyurethane sponge embedded in chlorhexidine (to reduce the surface tension) with continuous drip until the closure of the wound by second. Results: In all cases the wounds closed in full. We believe that there is a very close relationship between the frequency of intraoperative washes and the frequency of post surgical infections. In most cases after the corresponding washes of the wound we used the VAC system. In cases when the patient’s social health system did not provide it, we handled with polyurethane sponges with continuous dripping. Both systems gave us exactly the same results, which were excellent since all the wounds healed without any inconvenience. Conclusions: After an exhaustive study of each of our patients we conclude that one system (VAC) or the other (sponges) are identical in their results and that the post surgical infections are much more prevalent when the intra operative washing is insufficient. This method is usually used in our service with good results.

P235 - Thoracolumbar Tubercular Spondylodiscitis: Experience Of The Outcome Of Single Stage Posterior Surgical Approach

M. Asraf Ul Matin Sagor¹

¹Junior Consultant, Orthosurgery, Shahidnagar Trauma Center, Daudkandi, Comilla - Bangladesh

Introduction: Spinal involvement occurs in less than 1% of patients with tuberculosis but the increasing frequency of TB in both developed and developing countries have continued to make spinal TB a health problem. Adequate early pharmacological treatment can prevent severe complications¹.Surgical management is needed along with ATT if there is no significant recovery. Materials and Methods: This is a prospective random experimental type of study. A total of 16 patients aged 18-46 years irrespective of sex were included in the study. The average age was 28.12 years. 56.3% patients were female and 43.8% male. Maximum 62.5% were dorsal followed by lumbar 25% and dorsolumbar 12.5%.We performed posterior decompression, stabilization & fusion in a single stage procedure. Results: Preoperative mean kyphotic deformity was 23.12⁰(range85^0_5⁰), which declined to 5⁰ (20⁰-0⁰) postoperatively. Preoperatively there was only 1 patient with ASIA score E, Postoperatively 9 patients achieved score E. Most clinical presentations were pain 81.3%, gibbus 75%, paraplegia 75%, weakness 25% and kyphoscoliosis 12.5% had significant clinico-radiological improvement. Maximum 62.5% patients achieved posterior bony fusion grade I, 31.3% grade II and 6.3% had fusion grade III. 75% patients had excellent outcome, 12.5% good, 6.3% fair and 6.3% poor outcome on Modified Macnab criteria. Conclusions: Approach for surgical treatment of thoracolumbar tuberculosis is always controversial. Traditionally, the anterior approach has been preferred throughout the spine². Posterior approach has gained popularity in the last decade as it provides excellent exposure for circumferential spinal cord decompression and also allows posterior instrumentation to be extended for multiple levels, above and below the level of pathology ³. Single stage posterior surgery can be a dimension to achieve satisfactory clinical outcomes in patients with thoracolumbar TB spondylodicitis.

References

1. Rasouli MR, Mirkoohi M, Vaccaro AR, Yarandi KK, Rahimi-Movaghar.V Spinal Tuberculosis: Diagnosis and Management. Asian Spine J. 2012 December; 6(4): 294–308.

2. Benli T, Kaya A, Acaroglu E. Anterior instrumentation in tuberculous spondylitis: Is it effective and safe? Clin Orthop Relat Res. 2007;460:108–16.

3. Pandey BK, Sangondimath GM, Chhabra HS. Single stage posterior instrumentation and anterior interbody fusion for tuberculosis of dorsal and lumbar spines. Nepal Orthopaedic Association Journal 2011;2(Number 1):22-26

P236 - Multidrug-Resistant Tuberculosis of the Spine in a Child Requiring Two-Staged Surgical Approach. Case Report

Carlos Montero¹, Wilmer Godoy¹, Fernando Alvarado¹, David Meneses¹, Alexander Tristancho¹

¹Department of Spine Surgery, Roosevelt Institute, Bogotá - Colombia

Introduction: Spinal tuberculosis is a relatively common form of extrapulmonary tuberculosis, it accounts for the 50% of bone tuberculosis, the 4% for all forms of tuberculosis including pulmonary. It has a wide range of prevalence an incidence regarding the country or region analyzed, varying from 0,05 cases per 100.000 inhabitants in E.U to 0,1 per 100.000 in Taiwan. It has been estimated that spinal TB occurs in 1,7% of global population but at 2016, 2.040 cases were reported worldwide. No prevalence studies regarding the occurrence of spinal tuberculosis have been performed in Colombia. MDR tuberculosis is defined as a strain that is resistant to Isonizid and Rifampicin and XDR when in addition to the previous antibiotics the bacillus shows resistance to injectable medication. In 2016 there were 440 000 new cases around the world of MDR TB infection and in high-burden areas, 15-20% of patients corresponded to pediatric population. Mainly because most cases are due to non resistance strains of Mycobacterium tuberculosis complex, the incidence of infection of the spine due to MDR or XDR strains is not established and there are only case reports and series. Materials and Methods: An 8 years old female patient from the Colombian forest region is admitted in our institution for 6 months lasting presence of granulamatous lesion with fistula in the middle back associated with diminished strength in the lower limbs and loss of sphincters control. Patient had history of previously diagnosed spinal tuberculosis 8 months before admission with no clinical control after that. After the first hospital discharge patient underwent standard anti-tuberculosis therapy (HRTZ) in his place of residence. Plain whole spine radiographs and simple magnetic resonance was performed at admission. The images showed typical findings of spinal tuberculosis with destruction of T8 vertebral body and kyphosis luxofracture. Culture isolation and quick molecular tests showed Mycobacterium tuberculosis complex with MDR phenotype. Results: Patient underwent two stage (anterior/posterior) surgical approaches with spinal fixation and tibial allograft insertion. Patient received discharge with anti MDR-TB chemotherapy (moxifloxacine, cicloserine, etionamide, pirazinamide, etambutol and isoniazide) and TLS orthesis. Paraplegia persisted at hospital discharge. Conclusion: Tuberculosis of the spine is a relatively frequent diagnosis in high burden regions like the Americas but its presentation in pediatric population and association with MDR strains is rare. Its diagnosis still remains a clinical challenge due to the insidious presentation and differential diagnosis with piogenic abscess. There is no consensus about the best surgical approach in cases like this one but the three scenarios have been proposed being single anterior, single posterior or combined approach. In this particular case, although no neurological improvement was achieved, patient obtains excellent stabilization of the thoracic spine.

P237 - Treatment Of Aeromonas Hydrophila Infection After Spinal Surgery: A Report Of 9 Cases

Yu Jiang¹, Zhongqiang Chen¹, Zhaoqing Guo¹, Qiang Qi¹, Weishi Li¹, Yan Zeng¹, Chuiguo Sun¹

¹Department of Orthopaedics, Peking University Third Hospital, Beijing - China

Introduction: Aeromonas hydrophila infection is relatively rare in spinal surgery incisions. Aeromonas hydrophila is a heterotrophic, Gram-negative, rod-shaped bacterium mainly found in areas with a warm climate. A. hydrophila was isolated from humans and animals in the 1950s. It can survive in aerobic and anaerobic environments, and can digest materials such as gelatin and hemoglobin. Material and Methods: From December 2012 to June 2017, 9 cases with A.hydrophila infection after spinal surgeries were treated, including 4 males and 5 females. 7 cases received posterior lumbar interbody fusion surgeries, 1 case with adolescent idiopathic scoliosis received spinal corrective surgery, 1 case with thoracic tumor received posterior decompression surgery. The average age is 54 years old. 9 cases of drainage fluid bacterial culture or blood bacterial culture were found A.hydrophila. According to the results of laboratory drug sensitivity, we adjusted the types and consumption of intravenous and oral antibiotics. 6 cases that we found large amounts of pus in deep incision on MRI received complete debridement. We put the opposing direction of the drainage tubes to flush the spinal surgical incision. We monitored the body temperature, ESR, CRP, PCT and blood routine test to assess the treatment of infection. It depends to the results of three consecutive days of drainage fluid culture, we decide whether to pull out the flushing tube and drainage tube. Two cases were treated with intravenous and oral sensitive antibiotics, and surgical incision infection was treated without debridement. Results: 9 cases recovered when they received suitable treatment, the body temperature, ESR, CRP, PCT and blood routine test were normal. Follow-up duration last from 2 to 53 months, an average of 10 months. No infection recurred during final follow-up. 9 cases of wound drainage fluid were cultured A.hydrophila. 4 cases of blood culture were found A.hydrophila. Fever started from the 3 rd day to the 12th day after surgery, the average starting time is 5.2 day. The highest body temperature was from 37.9°C to 39.9°C, an average of 39.0°C. The duration of using intravenous antibiotics was from 15 to 82 days, an average of 31.8 days. All cases were found that the most sensitive antibiotic to A.hydrophila was Ertapenem. 6 cases who received debridement reserved the internal fixation. Conclusion: A.hydrophila infection is relatively rare in spinal surgery incisions. A.hydrophila infection of spinal surgery incision results in the rapid onset of hyperthermia (6/9), the higher incidence of bacteremia (4/9). Blood and drainage culture positive rate of A.hydrophila is high, early detection helps to use exact intravenous antibiotic therapy. Reasonable use of antibiotic, combined with complete debridement and opposing catheter drainage, can realize effective treatment of A.hydrophila infection after spinal surgery.

P239 - Prevalence Of Surgical Site Infection In Spine Surgery In A Fourth Level Hospital In Bogota From 2010 To 2015

Maria Teresa Domínguez¹, Maria Alejandra Garcia¹, Fernando Alvarado², Maria Constanza Bedoya¹, Gilmar Leonardo Hernandez¹, David Meneses², Luis Carlos Morales¹, Andres Rodriguez¹

¹Department of orthopedics, Fundacion Santa Fe de Bogota, Bogota - Colombia ²Department of Spine Surgery, Roosevelt Institute, Bogota - Colombia

Introduction: Surgical Site infections (SSI) are defined by the Center for Disease Control (CDC) as superficial, or organ space infections occurring within 30 days after surgery (or within 1 year of hardware implantation). The etiology of postoperative infection is multifactorial and often related to a combination of preoperative, intraoperative, and postoperative factors (2). SSI after adult spinal surgery has been reported to occur in 0.7% to 12.0% of patients and can result in higher postoperative morbidity, mortality, and health care costs (3). Materials and methods: To determine the prevalence of operative site (ISO) infection in patients undergoing spinal surgery in a fourth level hospital. Cross - sectional, observational, descriptive study in which the clinical records of patients with spine surgery diagnosed with operative site infection at the Santa Fe University Hospital of Bogotá between 2010 and 2015 were reviewed. Results: Prevalence of infection of the operative site 2010-2015 was 29 of 853 surgical procedures of column corresponding to 0.034%. The age range included patients between 24 and 69 years with an average of 63.6 years of age. In the majority the population corresponded to women with 79.3% and men 20.69%. The mean body mass index was within normal ranges with a mean of 23.6. The mean hospital stay was 27 days. Conclusions: The results of the prevalence of postoperative site infection after spinal surgery in adult patients occurred in 0.034% with a result lower than the reported range in the literature that is between 0.7% and 12%. Given the incidence of this pathology and that there are modifiable factors, it is important to impact at this level to avoid, thus, the morbidity and mortality represented by this pathology, and what it represents for the Health System.

P240 - Development Of A Checklist For Spine Surgery As A Strategy To Prevent Surgical Site Infection (Ssi) For A Fourth-Level Hospital In Bogotá, Colombia

Gustavo Rozo¹, Fernando Alvarado², Maria Teresa Domínguez¹, David Meneses², Luis Carlos Morales¹, Maria Constanza Bedoya¹, Andres Rodriguez¹

¹Department of orthopedics, Fundacion Santa Fe de Bogota, Bogota - Colombia ²Department of Spine Surgery, Roosevelt Institute, Bogota - Colombia

Introduction: Surgical site infections (SSI) are located within the definition of nosocomial infections, and are recognized as the third cause of nosocomial infection, with an incidence range of 14 to 16%. SSI rates of 0.7 to 12% have been reported in spine surgery patients. The purpose of this study is to include a checklist for Spine Surgery section of our institution as an SSI prevention strategy. Materials and Methods: Structured literature review by collecting information from studies related to advantages in the use of checklists in spinal surgery and its relationship with variables that have better scientific support in decreasing the infection of the operative site was performed. Data was collected from Medline, EMBASE, Ovid, and others (Medline, EMBASE, Ovid, Web of Science and Cochrane databases) and selection by specific risk factors for spine surgery was achieve. Finally, a selection of the most relevant risk factors was implement and a checklist of prevention of SSI was developed. Results: After the review of the literature a list of variables was generated and, according to the risk factors, the ones that best fit our environment were selected and divided into categories: surgical room and preoperative, surgical and postoperative time. Finally, a checklist was built to be adhered to the protocol of management of the patients of spine surgery of the institution. Conclusions: The available evidence for spine surgery checklist is limited, so referrals are used in surgery and pediatric spine surgery. The checklists have been shown to be a useful tool in the reduction of SSI in the referents found in the literature, which is why the creation of a checklist is justified. The next phase of the project will be the implementation of the checklist to evaluate the impact within the infection rate of the institution’s spine surgery team.

P241 - Cervical Spondylodiscitis As A Rare Complication Of Long Term Neurodermatitis

Stipe Corluka¹, Vide Bilic¹, Stjepan Dokuzovic², Srecko Sabalic³

¹Department of Spinal Surgery, Traumatology Clinic, University Hospital Centre Sestre Milosrdnice, Zagreb - Croatia ²Department of Traumatology and Orthopedic Surgery, University Hospital Dubrava, Zagreb - Croatia ³Traumatology Clinic, University Hospital Centre Sestre milosrdnice, Zagreb - Croatia

Introduction: Spondylodiscitis, a term encompassing vertebral osteomyelitis, spondylitis and discitis, is the main manifestation of haematogenous osteomyelitis in patients aged over 50 years. Staphylococcus aureus is the predominant pathogen, accounting for about half of non-tuberculous cases. Diagnosis is difficult and often delayed or missed due to the rarity of the disease, particularly in the cervical spine. Material and Methods: We present the case of a 57 year old female patient whose medical history was significant for nodal skin lesions encompassing her arms and forearms, her presternal region, and her back. Some lesions were encrusted due to previous hemorrhagic blistering from persistent scratching. She suffered from these skin lesions for twenty years, treated them withtopical ointments, and was followed up at dermatologists. She was also referred for allergy testing which proved negative for all common contact, nutritive and inhalational allergens, and so her condition was diagnosed as a neurodermatitis. She presented to the emergency neurological department with axial neck pain referring to the right shoulder and arm, she was non- febrile and with no neurological impairment. She was discharged with a diagnosis of cervicobrachial syndrome and referred to physical therapy and rehabilitation specialist. The next day she developed an increased temperature of 39.7 ^oC with rapidly worsening axial neck pain and symptoms of septicaemia and was admitted urgently in a clinic for infectious diseases. Bloodculture was positive for methicillin susceptible staphylococcus aureus (MSSA) and antibiotic therapy with cloxacillin was promptly initiated. Four days later she began manifesting motor deficits in the distribution of myotomes C4 - (strength ⅗), C5 - (⅗), C6 - (⅕), C7 - (⅘), C8 - (⅘). An emergency MRI of her cervical spine showed an paravertebral abscess in the right C3-C7 region and MRI characteristics of spondylodiscitis of her C5 and C6 vertebral bodies. She was then urgently transferred to our clinic for emergent surgical treatment. We performed a left sided anterior cervical approach, corpectomy of C5 and C6, drainage of the abscess, lavage and reconstruction of the anterior column with a MESH cage filled with autologous trabecular bone from her ipsilateral iliac crest and anterior cervical locking plate fixation from C4 to C7. Results: The immediate postoperative period was uneventful. Her neck was immobilized with neck collar. Immediate postoperative visual analog scale (VAS) pain score was 3-4/10 using NSAID only. Rifampicin was added to her anthibiotic regiment immediately postoperatively to prevent biofilm formation along the implant. Drainage was removed on the second postoperative day and her fever subsided. Neurologic improvement was witnessed by the third postoperative day. She was transferred back to the infectious diseases clinic from where she was initially transferred to us for further intravenous antibiotic treatment as per the spondylodiscitis protocol. Conclusion: Spondylodiscitis can be a rare complication of pyogenic skin infection, including one resulting from neurodermatitis due to breach in skin integrity from persistent scratching.

P242 - Role Of Internal Fixation In Accelerated Rehabilitation Of Patients With Post Operative Discitis - Functional And Radiological Outcomes - Case Series

Aditya Banta¹, Saumyajit Basu¹, Amitava Biswas¹, Anil Solanki¹

¹Neurosciences Division, Park Clinic, Kolkata - India

Incidence of infection after a lumbar disectomy is about 0.21-3.6%. Literature regarding appropriate treatment of Post operative discitis (POD) is scarce. Central to all treatment options is use of long term antibiotics and bed rest till the patient is sufficiently pain free. Traditionally fixation surgeries have been reserved for cases where severe back pain persists despite treatment for infection. Material and Methods: 6 consecutive patients of POD presenting to our institute from 2009 to 2014 underwent percutaneous fixation and biopsy. All patients were mobilized out of bed 24 hours after surgery. A total of six weeks of antibiotic course was given. Functional scores in form of ODI and VAS were used for assessment of patient’s functional status preoperatively, at time of discharge and at follow up visits (1 month, 3 month, 1 year). Xray and CT scan was done at 2 years follow up to assess fusion. Results: Six patients (4 male and 2 female) presented with postoperative discitis at L4/5 vertebral level. Most common microorganism isolated was Staphylococcus Aureus. Average time to onset of symptoms after index surgery was 19.83 (range 14-28). Average duration of hospital stay was 5.83 (range 4-13). Average ODI score at presentation was 74.16 (range 64-82) and it improved to 30 (range 20-46) at discharge (p value). VAS score improved from 8.67 (range 8-9) to 3 (range2-5) at discharge. Improvement in ODI score and VAS were seen in subsequent visits at 1 month were 16.67 (range 8-36) and 2 (range1-4) respectively. These scores improved to 8.67 (range 4-20) and 1.16 (range 0-3) at 1 year. Xray and CT scan done at 2 years documented fusion in all cases. Conclusion: Percutaneous fixation surgery along with antibiotics could be a viable treatment option for POD. Ability to instate accelerated rehabilitation with this treatment protocol could be considered as the most significant advantage over other methods of treatment.

P243 - Pott’s Disease: A Decade Of Experience In A Single Tertiary Centre In Malaysia

Fadzrul Abbas Mohamed Ramlee¹, Kamalnizat Ibrahim², Azmi Baharudin², Mohd Hisam Muhamad Ariffin²

¹Department of Orthopaedics and Traumatology, University Kebangsaan Malaysia Medical Centre, Kuala Lumpur - Malaysia ²Department of Orthopaedics and Traumatology, Universiti Kebangsaan Malaysia Medical Centre, Kuala Lumpur - Malaysia

Introduction: The incidence of tuberculosis remains high despite multiple measures taken. Pott’s disease not only becomes a burden to the particular individual patient, but to the community as a whole in terms of healthcare and economy. Despite the devastation that may be caused by spinal tuberculosis, national level study and data regarding management is disappointingly scarce. Materials and Methods: A retrospective study of patients with spinal TB over a 10-year period in Universiti Kebangsaan Malaysia Medical Centre (UKMMC) was conducted. Demographic data, clinical features, underlying diseases, laboratory results, imaging findings, therapy, treatment given and outcomes were analysed. Results: Seventy seven confirmed spinal tuberculosis patients were included and analysed. The mean age was 43.9 years with more female than male. The most common presenting symptoms were backache and neurological deficits. The most common vertebral area involved was thoracic spine (53.2%) with most having 2 or more vertebra involved. Surgery was carried out on 21 patients (27.3%). All patients received a minimum mandatory 6 months anti-tuberculosis chemotherapy. There was significant improvement in terms of kyphosis deformity correction for patients who had surgery done (p < 0.01). there was significant improvement in functional outcome at 2 years follow up for all patients, either treated surgically or with chemotherapy alone (p < 0.001). Conclusion: Working age patient complaining of back pain should be screened for spinal tuberculosis especially in patients with compromised immune status. Chemotherapy prescribed in line with current guidelines is the pillar of therapy and is started as soon as clinical and screening investigations are positive. It is also proven that a radical debridement and construct surgery has significantly reduced kyphotic angle compared to posterior only construct and chemotherapy alone regime. Functional outcome is good after 2 years of follow up for all patients. Adoption of the ‘middle path regime’ is the best approach in management of spinal tuberculosis as surgery remains indicated for debridement, draining of abscess, decompression in neurological complicated patients and to halt or correct kyphotic deformity. Surgery is not indicated for patients with mild form of presentation and has no deterioration of disease after commencement of anti-tuberculosis medication. Our principle follows the currently accepted management worldwide.

P244 - Low-Grade Infection In Spinal Instrumentation: Is This The Real Cause Of Screw Loosening?

Ehab Shiban¹, Bernhard Meyer¹, Insa Janssen¹, Mohammed Isa¹

¹Department of Neurosurgery, Technical University of Munich, Munich - Germany

Introduction: We investigated the hypothesis that many aseptic screw-loosening revisions in spinal instrumentations are in fact low-grade infections and not due to mechanical screw overload. Material and Methods: A prospective observational study was performed. All patients undergoing spinal instrumentation revision surgery between August 2015 and June 2016 were screened. In the study group all patients with an indication for revision due to screw loosening on CT-scan were included. In the control group those needing revision for adjacent disc disease were included. The rate of low-grade infection using a sonification fluid culture was analyzed. Results: 65 patients met all inclusion criteria. 61 patients were enrolled. Median age was 71 years (range 41-83). 33 patients (53%) were female. There were 35 (57%) and 26 (43%) patients in the study and control group, respectively. A low-grade infection was identified in 14 (40%) and 7 (26%) cases in the study and control group, respectively.

This difference was however not statistically significant. All patients with positive cultures received postoperative antibiotic treatment. Conclusion: The rate of low-grade infections in patients undergoing spinal instrumentation revision surgeries is high. Thereby, there were so significant differences between the control and the study group. So far, there is no clear evidence supporting the hypothesis that a low-grade infection is the cause of screw loosening.

P245 - Three Columns Involvement In Non-Tuberculous Spinal Infections

Mohamed Abdel-Wanis Mohamed¹, Nahla M Hasan Dr Nahla M Hasan²

¹Department of Orthopedic Surgery, Sohag - Egypt ²Department of Diagnostic Radiology, Sohag - Egypt

Introduction: Non-tuberculous spondylitis is the most common form of spinal infection and approximately 80% of the cases of spinal infection are caused by staphylococcus aureus. Involvement of the neural arch is rare in spinal infections. Typically, infectious spondylitis show involvement of two or more adjacent vertebral bodies with involvement of the intervening disc. Although there are some reports in the literature include limited number of patients with 3 column involvement in tuberculous spinal infection, 3 column involvement in non-tuberculous infection did not attract much attention. Materials and Methods: MRIs of all patients who had been diagnosed and surgically treated for non- tuberculous spinal infection in Sohag University Hospital, Sohag, Egypt were reviewed. All patients with 3 column involvement and proved by culture and biopsy to have non-tuberculous infection were evaluated for degree of spinal deformity, vertebral body and disc damage and paravertebral and epidural abscess formation. Results: Sixteen patients (10 males and 6 females) with a mean age of 66.6 years fulfilled the inclusion criteria. Infection was in the thoracic region in 2 patients, in lumbar spine in 12 patients and at the lumbosacral junction in 2 patients. Vertebral body collapse was present in 10 patients (71%) however, did not exceed 49%. Disc destruction was complete in 6 patients, and partial in 5 patients. Kyphotic deformity was not found in any case. Paraspinal and epidural abscesses were found in 88% and 69% respectively. Conclusion: Three column spinal involvement in non-tuberculous infection might be not so rare. It seems to be commoner in the lumbar spine. Vertebral body and disc destruction and paraspinal and epidural abscesses are common in these case.

P246 - Pyogenic Spondylodiscitis: Mid-Term Results Of Surgically Managed Patients

Tuna Pehlivanoglu¹, Turgut Akgul¹, Serkan Bayram¹, Koray Sahin¹, Murat Korkmaz², Cuneyt Sar¹

¹Istanbul University, Istanbul Faculty of Medicine, Department of Orthopedic Surgery and Traumatology, Istanbul - Turkey ²Istanbul Koc University, Medical Faculty, Department of Orthopedic Surgery and Traumatology, Istanbul - Turkey

Introduction: Spondylodiscitis was defined as the infection involving intervertebral discs and vertebral bodies. It was reported to be mainly caused by pyogenic and granulomatous agents and to cause high rates of morbidity and mortality. Surgical treatment was advocated when medical treatment was not sufficient by taking the pathology under control. There is still an ongoing debate about the ideal surgical technique for the treatment of pyogenic spinal infections. The aim of this study was to present the mid-term results of patients diagnosed with pyogenic spondylodiscitis (PSD). Material and Methods: Twenty-seven patients (14 females, 13 males) operated between 2006-2016 with a diagnosis of pyogenic (bacterial) spondylodiscitis were evaluated retrospectively. Among them, 19 patients who came regularly to follow-up appointments and could fill clinical questionnaires were enrolled in the study. Patients co-morbidities, pre- and post-operative VAS scores, post-operative SF-36 scores, pre- and post-operative complications, laboratory values, follow-up periods, duration of hospital stays, results of intraoperatively taken cultures-inoculated microorganisms and fusion status at latest follow-up appointments were recorded. Results: Patients had a mean age of 61 and a mean follow-up period of 40 months. They were detected to have a mean, pre-operative CRP level of 67, ESR of 75 and a WBC of 9120.Diagnoses of all patients were confirmed with MRI. Patients had mean a pre-operative VAS score of 7.8 and a mean post-operative VAS score of 2.3 (p < 0.001). Mean SF-36 MCS/PCS scores that were calculated during the final follow-up appointment were 44.7/49.3 respectively. Fifteen patients were detected to have heavy co-morbidities including diabetes mellitus, multiple myeloma, cirrhosis, colon-bladder cancer. Four patients were detected to have a prior spinal surgery as the cause of pathology. Patients were noted to have a mean duration of hospital stay of 16 days. Five patients were operated with a diagnosis of isolated thoracic, 10 because of isolated lumbar and 4 with a diagnosis of thoracic and lumbar spondylodiscitis.5 patients underwent anterior debridement and posterior fusion, 7 patients underwent corpectomy and fusion, remaining 7 patients underwent debridement and interbody fusion through posterior approach. After corpectomy, to achieve fusion, application of a cage was performed in 5 patients (26%) (involvement of vertebral bodies >50%). Five patients (26%) had an involvement of 25-50% of the vertebral bodies). Two of them (10%) underwent application of interbody cage; while 3 of them(18%) underwent fusion with tri-cortical grafting from iliac wings. 5 patients (26%) underwent fusion without grafting and cage application because of the involvement of vertebral bodies less than 25%.The rest (4 patients, %22) underwent debridement only because of the isolated involvement of discs. Bacterial growth was detected in 42% of patients’ intra-operatively taken specimens. MSSA was isolated in 7 patients (36%), while MSKNS was isolated in one patient. Solid bony fusions were detected in 17 patients (90%) during the final follow-up visit. Conclusion: PSD that usually affects elderly population with heavy co-morbidities is a challenging diagnosis for spinal surgeons. There are many proposed methods of treatment that usually result in instability which necessitates surgical treatment. Our study concluded that interbody fusion, techniques of anterior and posterior instrumentation and debridements were safe and effective treatment options for patients with PSD.

P247 - Gender Differences In Spinal Infection: A Single-Center Retrospective Study Of 159 Cases

Sara Lener¹, Sebastian Hartmann¹, Claudius Thomé¹, Anja Tschugg¹

¹Department of Neurosurgery, Medical University of Innsbruck, Innsbruck - Austria

Background: Spinal infection (SI) is defined as an infectious disease affecting the spine and/or paravertebral tissue and is still known as a life-threatening condition. Numerous factors may facilitate the course and outcome of SI, including patient’s age and comorbidities, as well as gender. To date, no comparative data investigating sex differences in SI is available. Thus, the purpose of the present retrospective trial was to investigate differences between male and female patients. Methods: 159 patients that were treated due to a spinal infection at our department between 2000 and 2016 were included in the retrospective analysis. The patients were categorized into two groups based on gender. Evaluation included MRI, laboratory values, clinical outcome and conservative/operative management. Results: Male patients suffered from SI significantly more often than female patients (n = 101, 63,5% vs. n = 58, 36,5%, p = 0.001). Female patients were initially affected more severe, as infection parameters were significantly higher (p = 0.032) and vertebral destruction was more serious (p = 0.018). Furthermore, women suffered from intraoperative complications (p = 0.024) and received erythrocyte concentrates more frequently (p = 0.01). Nevertheless, death rates were equal, and outcome was comparable. Still, pain scales were significantly higher in female patients at 12 months follow-up (p = 0.042). Conclusion: Although male patients show a higher incidence for SI, the course of disease and the management is less challenging than in female patients. Nevertheless, outcome after 12 months is comparably good. Underlying mechanisms for this adaptation may include better immune response and dissimilar effects of antibiotic treatment in women. Still, further prospective clinical trials will be mandatory.

P248 - Widely-Disseminated Mtb-Pcr-Negative, Culture-Negative Pott’s Disease In A 13-Year Old Male: A Case Report

Daniela Kristina Carolino¹, Mario Ver¹, Miguel Rafael Ramos¹, Monica Pecache¹

¹Institute of Orthopedics and Sports Medicine, St. Luke’s Medical Center, Quezon City - Philippines

Introduction: Tuberculosis is regarded as one of the world’s deadliest diseases, burdening 10.4 million individuals in their productive years. Extrapulmonary tuberculosis accounts for one fourth of worldwide cases and can be diagnosed accurately using polymerase chain reaction and culture mediums. Here we report the only documented case of MTB-PCR and culture-negative disseminated tuberculosis, involving multiple skeletal and spinal segments, in a teenage, Asian male. Material and Methods: We describe the clinical course of the patient as well as the unusual radiological findings, diagnostic tests performed and the process by which his diagnosis was established, as well as the medical management and surgical procedures done that afforded him some alleviation of his symptoms but not cure from his disease. Results: A 13-year old Filipino male presented with sudden onset cervical radiculopathy without antecedent trauma nor classic symptoms of tuberculosis. Neurological examination revealed mild motor deficits from C5 to T1 bilaterally without sensory deficits nor myelopathic signs. The patient underwent extensive diagnostic work-up and imaging which revealed atypical findings of multilevel, non contiguous involvement of the vertebrae affecting the cervicothoracic areas with affectation of posterior elements. He was then indicated for a staged procedure of cervical cord decompression and stabilization where intraoperative specimens were sent for investigation. Anti-Koch’s medications were likewise started. Conclusion: Considered a great mimicker of disease conditions, Pott’s disease, when highly suspected, should be considered as a differential diagnosis even in the face of negative diagnostic results and unusual radiologic presentations. Furthermore, the use of multitude of diagnostic examinations or imaging targeting extraspinal tuberculosis is better at understanding and uncovering the pathophysiology of the disease.

P249 - Socio-Economic Outcome Using Prolo And Denis Work Scale After Anterior Decompression And Cage With Bone Graft In Caries Spine Affecties

Haseeb Hussain¹

¹Department of Orthopedic and Spine Surgery, Ghurki Hospital, Lahore - Pakistan

Introduction: Spinal tuberculosis is a destructive form of tuberculosis. It accounts for approximately half of all cases of musculoskeletal tuberculosis. Tuberculosis of spine is one of the major causes of spinal deformity and paraplegia. Treatment of tuberculosis infection of spine is crucial. Surgical decompression and stabilization is considered in patients to prevent/treat complications arising as a result of the disease or where conservative treatment fails such as chemotherapy. Objective: The objective of this study was to determine the socio economic stability i-e out door activities in caries spine patients after anterior decompression and stabilization with cage. Material and Methods: It was a descriptive case series on 907 patients admitted at Ghurki trust teaching hospital either through emergency or through OPD after confirmation of diagnosis through history, labs and histopathology taken during anterior decompression and cage with autologous bone graft between 2003 to 2013. The patients were regularly followed upto 3 years.Initially the data were entered on Pre formed Questionnaire and then on SPSS 17.0. Results: The study included 907 patients with mean age of 38.16 ± 9.58 years. 278 (30.65%) patients were upto 15 years. 409 (45.09%) patients were between 16-40 years while the remaining i-e 220 (24.26%) were above 40. There were 550 (60.64%) male patients and 357 (39.36%) female patients in our study. 467 (51.49%) patients having Prolo economic score 5 and Denis work scale D1 i-e return their work. 289 (31.86%) patients with Prolo economic score 4 and Denis work scale D2 i-e return their work but with limited activity,89(9.8%) patients having Prolo economic score 3 and Denis Work scale D3 i-e change occupation, 22(2.43%) having Prolo economic scale 2 and D4 i-e didn’t return to their job doing house work or retirement activities and 40(4.44%) having Prolo economic scale 1 and Denis Work scale D5 i-e unable to do any activity. Conclusion: Prolo economic scale and Denis work scale significantly improved in patients undergone anterior stabilization and cage with autologous bone graft.The patients undergone this surgery can do their daily living activities mostly without any significant loss and hence the safety of this surgical procedure.

P250 - Posterior Only Approach For Lumbar Pyogenic Spondylitis

Ban Suk Go¹, Yong Min Kim¹

¹Department of Orthopedic Surgery, Chungbuk National University, Cheongju - Korea, Republic

Study design: A retrospective single-center study. Objective: To assess the efficacy of posterior only approach for decompression and interbody fusion with instrumentation in managing lumbar pyogenic spondylitis. Summary of Background Data: Several methods of surgical treatment for pyogenic spondylitis have been reported, there have been few reports regarding the efficacy of posterior approach with instrumentation. Methods: Thirty-three patients with lumbar pyogenic spondylitis who underwent posterior decompression and lumbar interbody fusion with transpedicular screw fixation were enrolled. Clinically infection control(CRP normalization time) and onset of ambulation were reviewed. And radiologically, achievement of fusion and changes of sagittal alignment were investigated. Results: In all the 33 cases, infection was controlled successfully without any recurrence. There was no breakage of implant. Postoperative interval to normalization of CRP was average 25.4 (10-64) days. Ambulation was started on 5.8 (2-19)th day. Successful interbody fusion was confirmed radiologically in all the cases within 6 months. Sagittal angle of fixed segments was average 12.3 degrees lordosis before operation, which became more lordotic to 16.4 degrees just after operation, but decreased to 11 degrees at the final follow-up. Actually final sagittal alignment was almost same as preoperative status. Conclusions: By achieving favorable clinical and radiological results, decompression and interbody fusion via posterior only approach seemed to be an effective method in managing lumbar pyogenic spondylitis.

Keywords: lumbar pyogenic spondylitis, posterior only approach, interbody fusion

P251 - Spinal Tuberculosis: Is The Disease Pattern Changing?

AK Sharma¹

¹Department of Neurosurgery, Landmark Hospital, Chandigarh - India

Introduction: Spinal Tuberculosis has affected humanity since antiquity. Despite several advancements in diagnosis, imaging, drug treatment, surgery as well as in public health delivery the disease continues to affect a significant number of populations in several countries across the globe. There is another aspect of the disease that oftentimes remains unanswered; whether the disease pattern has changed in the recent years? In this paper an attempt has been made to answer that question. Material and Methods: The clinical records of all the patients diagnosed and treated by the author from 2001 to 2015 were retrospectively analyzed and compared and contrasted with the data culled from major publications of 1970s when the principles of treatment of spinal tuberculosis were still evolving and were undergoing a major change. Similar data in recent published was also reviewed and the results of our analysis was corroborated. Results: 414 cases of spinal tuberculosis were included in this study. If the follow up was less than 6 months, the cases were excluded from the analysis. Major differences observed were in the age of peak incidence which has moved towards 6th and 7th decades of life, markedly reduced duration of symptoms at the time of presentation, significant reduction in the incidence of constitutional symptoms, near extinction of classical symptoms such as ‘night cries’, statistically significant reduction in the incidence as well as severity of spinal deformities, spinal abscesses and associated sinuses. Effective drug therapy has notably reduced mortality/morbidity and improved the outcome. Improved surgical approaches and availability of reliable implants have further enhanced the outcome. The downside is of course emergence of multidrug resistant strains of the organism. Patients who underwent surgery showed dramatic improvement in their pain symptoms, neurological status, kyphotic angle, posture and general health. Conclusion: Despite the unprecedented improvement in the health standards of populations across the continents, advancements in antibiotics, improvements in surgical techniques, implants and instruments, spinal tuberculosis offers a formidable challenge to the spine surgeon. The disease pattern, presentation, and outcomes have changed dramatically when compared with the data published about 40 years ago. The disease with a largely dismal outlook in the past appears to offer a rewarding experience for the spine surgeons in most of the cases.

P252 - Atypical Spinal Tuberculosis Involved Noncontiguous Multiple Segments: Case Series Report With Literature Review

Linnan Wang¹, Lei Wang¹, Li-min Liu¹, Yue-ming Song¹, Yue Li², Hao Liu¹

¹West China Hospital, Chengdu - China ²Department of Orthopedics, Sichuan Orthopaedic Hospital, Chengdu - China

Introduction: In its typical form, spinal tuberculosis (TB) presents as destroyed contiguous vertebral bodies with involvement of intervertebral discs and paravertebral or psoas abscesses. Atypical forms are uncommonly reported. Here we describe eight patients with noncontiguous multi-segmental spinal TB with no intervertebral disc involvement. Materials and Methods: From 2013 to 2014, we surgically treated 384 patients with spinal TB to relieve spinal cord compression, re-establish spinal stability, confirm the diagnosis, and debride the TB foci. Eight of these patients had noncontiguous multi-segmental TB without intervertebral disc involvement. Seven of the eight patients underwent short-segmental fixation and fusion at a single focus. Appropriate combinations of anti-TB medication were continued until final follow-up. They were followed at established intervals using plain radiography, three-dimensional computed tomography, and magnetic resonance imaging of the surgical region to evaluate fusion and the condition of the foci. Results: Mean follow-up was 26.6 months (range, 24–32 months), during which time all patients were prescribed the appropriate anti-TB medications. Satisfactory clinical and radiological results were obtained in all patients, without complications. Conclusions: Presentation of noncontiguous multi-segmental spinal TB without the involvement of intervertebral disc resembles that of a neoplasm or other spinal infection. Differentiation requires the presence of a combination of general symptoms, laboratory test results, appropriate radiological results, and the physician’s experience. For patients in whom surgery is indicated, the patient’s general condition should be taken into consideration. Surgical intervention only focus on the responsible level is less invasive and can achieve satisfactory clinical and radiographic outcomes.

P253 - Is It Possible To Use The Sins Criteria For Analysis Of Infectious Spondylitis?

Igor Sovpenchuk¹, Mikhail Mushkin², Denis Naumov³, Alexandr Mushkin⁴

¹Department of Extra-Lung Tuberculosis, St. Petersburg Research Institute of Phthisiopulmonology, Saint-Petersburg - Russian Federation ²Department of Orthopaedics and Traumatology, First Pavlov State Medical University of St. Petersburg, Saint-Petersburg - Russian Federation ³Pediatric Surgery and Orthopedic clinic, St. Petersburg Research Institute of Phthisiopulmonology, Saint-Petersburg - Russian Federation ⁴Pediatric Surgery and Orthopedics clinic, St. Petersburg Research Institute of Phthisiopulmonology, Saint-Petersburg - Russian Federation

Introduction: All of the spinal instability neoplastic score (SINS) criteria (pain severity, type of bone lesion, spine deformity, loss of vertebra height and posterior spine structure involving) usually detect in infectious spondylitis. Materials and Methods: 61 patients were operated due to infectious spondylitis including tuberculosis spondy - 20; acute pyogenic spondy - 15; chronic pyogenic spondy - 26, between 2016 and 2017. Level of spinal lesions, the SINS’ grade and visual analogue scale of pain (VAS) were evaluated. Analysis of variance was performed according to: 1) level of spinal pathology and SINS’ or VAS grade; 2) primary disease etiology and SINS’ or VAS grade; 3) a ranges of VAS (from 1 to 3; from 4 to 7; from 8 to 10) and grade of SINS. Statistical Package for the Social Sciences (SPSS), version 22.0 (SPSS Inc., Chicago, IL, USA) was used. A “p-value” less than 0.05 was considered statistically significant. Results: According to level of spinal pathology the mean grade of SINS and VAS were: 7.7 and 6.6 (for Cervical spine); 8.6 and 5.6 (Th); 10.6 and 6.1 (Th/L); 7.2 and 5.0 (L); 10.7 and 6.2 (L/S). Statistically significant differences were for SINS between “L” and “Th/L”, “L/S” spine (p₁ = 0.005, p₂ = 0.002); for VAS - between C and L spine (6.6 vs 5.0; p₃ = 0.024). We didn’t find statistically significant differences between grade of SINS or grade of VAS and primary disease etiology (p₄ = 0.508; p₅ = 0.759). According to ranges of VAS compare with SINS grade was detected increase correlation: VAS from 1 to 3 / the mean SINS – 6.5; VAS from 4 to 7 / the mean SINS – 8.4; VAS from 8 to 10 / the mean SINS – 10.6, but correlation was not significant (p₆ = 0.154). Conclusion: The SINS and VAS grades weren’t depends on primary disease etiology. The lowest SINS and VAS grades were observed in L spine. Pain severity relevant to VAS range from 4 to 7, spine instability relevant to “potential unstable” occurred in majority of infectious spondylitis patients.

P254 - Use Of Antibiotic Impregnated Cement Spacer In The Treatment Of Recalcitrant Vertebral Osteomyelitis – A Novel Technique To Treat Resistant Spinal Infections

Aju Bosco¹, Harvinder Singh Chhabra²

¹Center for Advanced Brain and Spine Surgery (CABSS), Tamilnadu Govt. Multi Superspeciality Hospital, Chennai - India ²Chief of Spine Services, Department of Spine Surgery, Indian Spinal Injuries Center, New Delhi - India

Introduction: Postoperative spinal wound infection (PSI) is a potentially devastating complication, presenting a nightmare to the patient and the surgeon alike. Reported rates of infections after spinal interventions vary widely(0.7%-16%) due to the differing invasiveness of the procedures. Despite the use of prophylactic antibiotics and advances in surgical technique and postoperative care, wound infection continues to compromise patients’ outcome after spine surgery due to the risk of pseudoarthrosis, instability, deformity, adverse neurologic sequelae and even death. PSIs with its ramifications increase the morbidity of the patient and the cost of health care. We describe a novel technique to treat recalcitrant PSI following instrumented spine surgery. Materials and Methods: We describe two patients with recalcitrant postoperative spinal infection following spinal stabilization, corpectomy and cage reconstruction for post-traumatic L3 AO A4 injury. Both patients had been treated with multiple wound debridements and antbiotics, and presented to us with neurodeficit, instability, persistent infection and sinus with discharge, at a mean of 8 months after the initial surgery.Patients underwent implant removal, sinus tract excision, radical debridement of infected tissue, anterior column reconstruction using Gentamycin(2 g) impregnated bone cement spacer and L2 toL4 posterior instrumented stabilization. Appropriate culture-specific antibiotics (Staphylococcus aureus/Linezolid) were administered intravenously(6 weeks) and orally(on the basis of clinical and laboratory parameters). Response to treatment was assessed by physical signs of well-being, ESR, CRP, signs of neurological recovery and functional outcomes[ODI (Oswestry Disability Index) scores]. Antibiotics were stopped when the clinical examination consistent with resolution of infection (well-healed wound, decreasing swelling and warmth, absence of erythema), a well-absence of back pain and normalization of serum inflammatory markers(ESR and CRP). After 7 months, cement spacers were removed and replaced with fibular strut graft through retroperitoneal approach. Results: At 63 months follow-up, both patients showed good clinical and functional outcomes(improvement in ODI scores), neurological improvement and radiographic evidence of bony fusion, with no signs of recurrence of infection. Conclusions: Despite the availability of a myriad of antibiotics and marked advances in surgical treatment, the long-term recurrence rate of PSI remains alarming at a rate of 20% to 30% .The optimal surgical modality to treat PSIs remains a matter of debate. PSI usually requires a variable combination of debridement, implant removal and prolonged antibiotic therapy. Implant removal leads to spinal instability which may itself lead to delayed healing and neurological compromise. Antibiotic-impregnated PMMA (Polymethyl Methacrylate) spacer offers immediate structural support by filling the defect created by radical debridement, restores and maintains spinal stability, while simultaneously releasing antibiotics in high local concentrations for prolonged periods. The local antibiotic levels vastly exceed the MIC(Minimum Inhibitory Concentration) needed for treating most susceptible pathogens, than those achieved with parenteral therapy. It reinforces parenteral antibiotic therapy. Gentamycin coated bone cement has shown greater effectiveness in reducing the biofilm formation, with minimal systemic toxicity. This is the first report on the use of antibiotic impregnated PMMA cement spacer in the management of recalcitrant post-operative vertebral osteomyelitis.

Keywords: post-operative, spinal infections, vertebral osteomyelitis, cement spacer, polymethyl methacrylate

Source of funding-NIL; Conflict of interest-NIL.

Medical Economics

P255 - Comparative Effectiveness Research (Cer) For Lumbar Fusion, Institutional Report

Michel Lacroix¹

¹Neurosciences Institute, Geisinger Health System, Wilkes Barre - United States

Introduction: Comparative effectiveness research (CER) allows for the study of heterogeneous group of patients with complex diseases process. One iteration of CER is the concept of practice-based research and practical clinical trial. Facilitated by the Electronic Medical record, the incorporation of best available evidence in the delivery of care is at the core of Geisinger’s ProvenCareTM Program. The program incorporates a combination of standardization, error proofing, failure mode redesign and effect analysis. These provider-driven process initiatives have reduced unwarranted variation in the care delivery and have been demonstrated to improve patient outcomes. We have applied this concept to a cohort of patients who underwent one or two level lumbar spinal fusions. Material and Methods: Observation study comparing patient candidate for one or two level lumbar fusion. Patient meeting inclusion criteria were enrolled in a ProvenCare program including 41 best medical practice (BMP) elements, encompassing the entire surgical episode from initial clinical visit to 90 days post op. To successfully complete the module, all BMP had to be met for all individual contact during the entire episode. Average length of stay (LOS) and 30 days readmission were the endpoint. Results: A total of 951 patients were included. 75 patients were enrolled in the ProvenCare program, 876 were not. The average LOS in the ProvenCare group was 2.4 days in comparison with 3.0 days in the comparative group. The readmission rate was 2.7% in comparison to 7.0% in the comparative group. Conclusion: Applying consistently BMP to a cohort of patients undergoing one or two level of spinal fusions improved LOS and decreased readmission at 30 days. This type of process could help optimize patient selection and their journey through the acute episode of care.

P256 - Will Cost Transparency In The Operating Theatre Cause Surgeons To Change Their Practice?

R. Andrew Glennie¹, Sean Barry², Jacob Alant², William Oxner¹, Sean Christie²

¹Department of Surgery, Division of Orthopaedics, Dalhousie University, Halifax - Canada ²Department of Surgery, Division of Neurosurgery, Dalhousie University, Halifax - Canada

Introduction: Cost containment continues to be increasingly emphasized in healthcare delivery, with a specific emphasis on surgical procedures. Many surgeons, however, do not have a thorough working knowledge regarding the costs of devices, surgical equipment and their impact on overall costs of care in a single payer system. There are a variety of possible explanations for this, including rapid technological advancement and price insensitivity. The purpose of this study is to determine whether surgeons will change their choice of implants/equipment once they are aware of the associated specific costs. Methods and Materials: A thorough bottom up case costing methodology was used to determine the costs of all implants used by a spine surgical service at a large tertiary care center. Costs were collected for an initial 5-month period (blinded) where surgeons were not aware of costs, followed by another 5-month period (unblinded) where detailed cost information was provided to the surgeons. Three procedures, anterior cervical discectomy and fusion (ACDF), posterior cervical fusion and lumbar interbody fusions were included. Statistical analysis was undertaken with STATA software. Results: Instrumentation costs decreased on average by $478 once actual prices were known, however this result was not statistically significant (p = 0.069). Only ACDF procedures demonstrated statistically significant average cost savings of $754 (p = 0.009). Procedural costs were not significantly less after blinding ($5717.71 blinded versus $5420.58 unblinded, p = 0.194) nor were the total average overall costs of admission ($10 461.41 blinded vs. $10 862.26 unblinded, p = 0.228). There were no significant differences in individual surgeon costs or in health-related quality of life (HRQOL) outcomes throughout the study. Conclusions: Although costs decrease for implants in surgery when prices are known, this appears to have little or no effect on overall costs of care. Length of stay and efficient use of operating room time appear to have greater effects on global costs. Future efforts to encourage efficient cost savings should focus on practice patterns for similar conditions rather than limiting the use of certain implants.

P257 - Medical Cost Analysis Of Mini Open-Alif Procedure For Degenerative Lumbar Spine Disease In Elder Patients

Kensuke Shinohara¹, Tomohiko Hirose¹, Kazuhiro Takeuchi¹, Shinnosuke Nakahara¹

¹Department of Orthopaedic Surgery, Okayama Medical Center, Okayama - Japan

Introduction: Recently, the expensive health care costs have become a social problem. The insurance system in Japan is the universal health insurance coverage, and the patient share of the total medical cost (TMC) is fixed with 30%. Under the system of the universal health insurance policy, there are very few reports in Japan about the health care cost. However, in recent years, cost-effectiveness of spinal surgical therapy has been discussed in the world. Aims: We have performed mini open-ALIF which is a minimally invasive procedure in the anterior lumbar spinal fusion for the patients with degenerative lumbar spine disease in our institute. We investigated medical records retrospectively and analyzed and compared the postoperative outcome and TMC between the young and elder patients and shows examined the cost value. Methods: Among the mini-ALIF cases in our institute since 2006, 105 patients were selected to this study (male 45, female 60). Inclusion criteria were single level fusion, stand alone method, and minimum follow-up of 1 year. Age, BMI, operative time, intraoperative bleeding, Japanese Orthopaedic Association (JOA) lumbar score at preoperative, postoperative and final follow-up, JOA improvement rate, length of hospital stay (LHS), and TMC were investigated. Also, the patients were divided two groups; Y group: the patients aged 64 years old or less. O group: the patients aged 65 years old or older. Examination items were compared in both groups. The correlation in JOA improvement rate and TMC in both groups were also investigated and compared. Results: In all cases, the mean age, operative time, intraoperative bleeding were 58 years old, 108 minutes and 50 ml respectively. The mean JOA score at preoperative and final follow-up were 17points and 26 points respectively. The mean JOA improvement rate was 75%. The average LHS was 19 days, and the mean TMC was $ 17 704. There were no significant differences in the operative time, intraoperative bleeding, JOA score, and JOA improvement rate between the two groups. The LHS and TMC were significantly lower in the Y group. The correlation of the JOA improvement rate and TMC was low in the two groups. Discussion and Conclusion: This study demonstrated mini open-ALIF procedure supplied the similar postoperative outcomes and the cost value in the young and elderly patients. In the young patients, compared to the older patients, the good condition without health history and preoperative activity was thought to have led to early discharge and TMC reduction.

Minimally Invasive Spine Surgery

P258 - Endoscopic Disc Space Debridement And Lavage - An Effective Newer Modality In Treatment Of Variable Etiology Spondylodiscitis

Swetabh Verma¹, Vineesh Mathur¹

¹Department of Orthopaedics and Spine, Medanta-the Medicity, Gurgaon - India

Introduction: Disc space infections are a common occurance in immune-compromised patients, in ICU setting as well as normal healthy individuals. They lead to prominent back pain with constitutional symptoms and thus significantly limit ambulation. Many of these patients are medically unfit for any surgical intervention, especially when the MRI scans reveal hyper-intense signals in the disc space in T2 and STIR sequences. Till now, not many studies have attempted to identify the efficacy of a percutaneous endoscopic procedure in such patients. Material and Methods: In our study conducted between November 2015 to December 2016 at Medanta-the Medicity, Gurgaon, India, a total of 16 patients were included, of which 10 were males and 6 females. The age group was between 45-72 years. Four spinal levels were considered from L2 to S1, most common level involved was L4-L5. Patients with extensive collapse of vertebra, instability and healed deformity were excluded. Preoperative haematological and inflammatory markers and VAS score was documented. A standard endoscopic procedure was followed in all patients wherein the disc space was approached percutaneously under local anaesthesia. After thorough debridement and collection of samples for biopsy, culture and sensitivity, the space was liberally lavaged. Post operatively and in follow up, the same markers were serially monitored along with VAS score at 3 weeks, 6 weeks and 12 weeks. Results: There was a gradual decline in the inflammatory markers with an improvement in VAS score. Three patients were lost in follow up due to expiry because of ongoing medical comorbidities and immune-compromised status. Rest 13 patients were ambulatory at last follow up with minimal back pain. Conclusion: Endoscopic disc space debridement and lavage under local anaesthesia is a safe and effective tool in patients with spondylodiscitis with no otherwise spinal instability.

P259 - Cement Leakage In Osteoporotic Vertebral Compression Fractures With Cortical Defect Using High-Viscosity Bone Cement During Unilateral Percutaneous Kyphoplasty Surgery

Tie Liu¹, Yong Hai¹, Yuzeng Liu¹, Li Guan¹

¹Beijing Chao-Yang Hospital Capital Medical University, Beijing - China

Introduction: The purpose of this study was to investigate cement leakage in osteoporotic vertebral compression fractures (OVCF) with cortical defect using high-viscosity bone cement during unilateral percutaneous kyphoplasty (PKP) surgery. Material and Methods: This study included a series of 77 patients (23 males, 54 females) with single level osteoporotic vertebral body fracture (OVCF) who underwent unilateral PKP in our hospital. Preoperative X-ray, computed tomography (CT) scan and three-dimensional reconstructions were studied. During the PKP procedure, needle was carefully put to avoid too near to the cortical defect according to CT image. High-viscosity bone cement was used via unilateral percutaneous kyphoplasty. Radiographic outcomes were evaluated by assessment of vertebral body wall breakage, fracture type, and vertebral body change. The exact rate of cement leakage was analyzed. Results: A total of 77 patients with single level OVCF were included in this study. The mean age of the patients was 74.8 ± 8.0 years old. Among these cases, seven (9.1%) involved the thoracic spine (T3∼T10), sixty (77.9%) involved the thoracolumbar spine (T10∼L2), and ten (13.0%)involved the lumbar spine (L3∼L5). There were 27 vertebral bodies found posterior wall breakage, 51 vertebral bodies found endplate breakage, and 49 vertebral bodies found anterior-lateral wall breakage. CT scan was more efficiently in detecting vertebral body wall breakage and cement leakage than X-ray (P<0.001). No neurological symptoms were found after surgery. Both cases with cement leakage (CL group) and cases without cement leakage (NCL group) experienced vertebral height restoration, which were found no significant difference between the two groups. Severe vertebral body fracture and biconcave fracture had more CL than other groups. OVCF cases with cortical defect had more CL rate than those without cortical defect. No significant difference was found in the correlation between vertebral wall breakage and CL. Conclusion: Cortical defect remains a potential risk of cement leakage during PKP surgery. Careful preoperative evaluation and using high-viscosity bone cement during the unilateral PKP procedure could prevent serious leakage and clinical symptoms.

P260 - Revision Endoscopic Interlaminar Lumbar Spine Decompression Surgery Using Destandau Endospine System: A Retrospective Study Of Clinical Outcome In A Single Institution

Wan Zainuddin Wan Ab Rahman¹, Abdul Halim Yusof²

¹Department Of Orthopaedics, Sultanah Fatimah Specialist Hospital, Muar - Malaysia ²Department Of Orthopaedics, Universiti Sains Malaysia, Kubang Kerian, Kelantan - Malaysia

Introduction: Revision surgery is known to be difficult and high risk. It faces serious technical challenges and the outcome is less than the index surgery. Endoscopic spine surgery is a minimally invasive surgery and is a very promising method with potential of providing better results. So far there is no study on the outcome of the revision endoscopic lumbar surgery. The aim of the study is to determine the feasibility of revision endoscopic interlaminar lumbar spine decompression surgery using Destandau Endospine system and to correlate the clinical outcome with the biodemographic factors. Materials and Methods: A total of 17 patients who underwent revision endoscopic lumbar spine surgery between December 2009 and September 2014 were followed up at a mean of 2.95 years (0.42 – 6 years). 3 cases had open surgery and others (14) were endoscopic surgery as index operation. 2 cases were wrong level of operation and the rest (15) were inadequate surgery as the reason for revision. 2 patients were excluded earlier due to loss of follow up. All except one (discectomy) undergone decompressive surgery. In addition to the biodemographic parameters, they were assessed in term of pain using Visual Analogue Scale (VAS), sensory score based on American Spinal Injury Association (ASIA) chart for numbness and muscle power based on Medical Research Council (MRC) grading for strength. While body capacity rating according to MacNab’s classification and Oswestry Disability Index (ODI) questionnaires were used for measuring the clinical outcomes. The complications were documented perioperative and postoperatively. Results: The results showed significant improvement in mean VAS for back pain (3.1 ± 1.83 to 2.1 ± 1.56, P = 0.015), leg pain (7.0 ± 1.28 to 4.2 ± 2.22, P<0.001), leg numbness (P = 0.041) and muscle weakness (P = 0.014). Based on the MacNab’s criteria, 9(53.0%) patients showed excellent or good outcomes while the other 8(47.0%) patients showed fair or poor outcomes. There were significant improvement in term of ODI with preoperative and postoperative mean of 57.2 ± 12.78 and 41.5 ± 19.10 respectively (P = 0.002). No significant relationship were found between MacNab’s criteria with gender, age group, medical problems, duration of symptoms, pain free interval, side of recurrence, duration of revision surgery and blood loss (P>0.05). The complication rates were low with one patient had delayed wound healing, infection and hamstring tightness, while 5(29.4%) patients had incidental durotomy. The mean operation time was 3.79 ± 1.11hours with median blood loss of 190.0 mL (IQR 170.0 mL) and mean postoperative hospital stay of 1.5 ± 0.51days. Conclusion: Revision endoscopic lumbar spine surgery using Endospine system provides an adequate and safe decompression with resulted in a significant improvement in the outcome.

P261 - The Application Of Midline Lumbar Fusion Technique (Midlf) With Minimally Exposure Approach-Report Of Preliminary Clinical Outcome

Hsiang-Ming Huang¹, Han-Chung Lee¹, Chao-Hsuan Chen¹, Der-Cherng Chen¹

¹Department of Neurosurgery, China Medical University Hospital, Taichung City - Taiwan, Province of China

Introduction: Conventional pedicle screw (PS) fixation is the current mainstay technique for posterior spinal fusion. Over the past decade, a newly developed pedicle screw insertion technique called cortical bone trajectory (CBT) screw fixation has been developed, which allows for medial to lateral screw placement through stronger cortical bone. In order to evaluate the clinical benefits of CBT technique in minimally exposure MIDLF technique, we present a prospective study of the preliminary clinical outcomes from the first 40 consecutive cases with percutaneous CBT fixation compare to the conventional PS technique. Material and Methods: From April 2016 to May. 2017, 40 patients (Male: Female = 11:29) with diagnosis of degenerative spine disease underwent singe to two level lumbar fusion technique using CBT fixation. And 24 patients (Male: Female = 7:17) underwent conventional open fusion surgery with PS technique. The mean follow up period is 6.3months. Clinical outcome were assessed by the pre and post-operative change of Creatine Phospho Kinase (CPK), Japanese Orthopaedic Association score (JOA), Visual Analogue Scale (VAS), and EuroQoL 5 Dimensions 5 Levels (EQ-5D-5 L), The operative time bloood loss and hospital stay were also recorded. Results: Our preliminary short term clinical outcome showed that there were no significant between-group differences in operative time or hospital stay but the CBT group experience significantly less blood loss, lower postoperative CPK levels. The clinical outcome follow up of CBT group present less VAS score, continue improving EQ-5D-5 L score and better JOA score. Conclusion: The lumbar fusion technique using minimally exposure MIDLF technique can provide acceptable surgical outcome with less soft tissue damage and blood loss. Short term clinical follow up of the CBT group also showed a trends of less postoperative wound pain and better functional outcome. Further studies with large patient numbers and longer follow up are needed to assess the clinical benefits in patients who undergo this modified lumbar spinal fusion technique.

P262 - Outcomes Of Mis Sacroiliac Joint Fusion Among Us Military Veterans Diagnosed With Sacroiliac Joint Pain: A Single-Surgeon Series

Andrew Schmiesing¹, Jonathan Sembrano¹, Sharon Yson¹

¹Department of Orthopedics, University of Minnesota, Minneapolis - United States

Introduction: In the 21st century, there has been a significant increase in attention to the sacroiliac joint (SIJ) as a source of low back pain. Many studies have shown positive outcomes of minimally invasive (MIS) SIJ fusion. The purpose of this study is to examine patient reported outcomes for this procedure in a United States Military Veterans population. Previous studies on other health conditions have suggested differences between normal and veteran populations, with the latter having lower health scores in addition to being predominantly male. Material and Methods: This study is a retrospective case series of our experience with twenty-one MIS SIJ fusions using triangular ingrown titanium rods in twenty patients at our local Veterans Affairs Medical Center from August 2011 through February 2014. Of our twenty patients, seventeen were male and three were female and they had an average age of 56 years. Surgical indications were based on history, physical exam, and diagnostic sacroiliac joint injections. Primary diagnosis was degenerative sacroiliitis in all cases except one of chronic SIJ infection. Patient reported outcomes (numeric pain scores and Oswestry Disability Index [ODI]) were collected pre and post operatively with final outcomes at greater than two years for all patients. Final follow up was at an average of 3.3 years and was completed for 18/20 patients. Results: At final follow up, ODI improved from 57.9 pre-operatively to 44.3 (p = 0.02) at final follow up. Signifiant improvement was seen by three months post operatively and this was maintained through final follow up. The VAS score for back pain improved from 6.7 to 5.8 at final follow up. The VAS score showed regression after the first year of follow up. Mean operative time was 96 minutes (range 53-244). Mean blood loss was an average of 80 cc (range 25-350). Mean hospital stay was an average of 1.5 days (range 1-4) with all but one patient discharging home from the hospital. There was one complication noted in our series which was a return to OR secondary to pseudoarthrosis. Conclusion: Minimally invasive sacroiliac joint fusion is an effective treatment of low back pain in the right patient.

P263 - MIS TLIF + Adjacent Segment Tubular Laminotomy FOR Spondylolisthesis WITH Bisegmental Stenosis; “One And A Half” Surgery

Christoph Wipplinger¹, Carolin Melcher¹, Rodrigo Navarro-Ramirez¹, R. Nick Hernandez¹, Eliana Kim¹, Roger Härtl¹

¹Department of Neurological Surgery, Weill Cornell Medicine, New York - United States

Introduction: Symptomatic lumbar spondylolisthesis is commonly accompanied by spinal stenosis in multiple segments. These pathologies are routinely treated by multilevel decompression and instrumented fusion. However, it was hypothesized that a minimally invasive (MIS) fusion in the unstable segment combined with a lone standing tubular decompression in the stenotic segments is a biomechanically feasible alternative to a two-level fusion and superior to open laminectomy adjacent to and instrumented fusion procedure. This concept has demonstrated success in a recently published biomechanical cadaver study (Grunert et al. Neurosurgery 2016). We hereby describe our operative technique and clinical outcomes of patients undergoing a single level minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) with additional decompressive tubular laminectomy in the adjacent segment. Material and Methods: All patients were treated by a single level MIS-TLIF and an MIS tubular decompression in the adjacent level (above/below). All procedures were performed with total navigation using a 3D navigation system, so without the need of intraoperative fluoroscopy. The tubular decompression of the adjacent level was then performed through a separate incision. We prospectively collected the data and retrospectively analyzed 15 patients, treated in our institution between 2014 and 2016. We assessed the surgical time (ST), estimated blood loss (EBL) and perioperative complications as well as implant accuracy and postoperative clinical outcomes (ODI, VAS for back and leg). Results: Mean age was 70 years ± 9. All patients suffered from monosegmental degenerative spondylolisthesis and adjacent stenosis between L1 and S1. The mean EBL was 136 ml ± 46, while the mean ST was 250 min ± 51. The postoperative length of stay was 4 days ± 1. During that period, no postoperative complications were observed and none of our patients showed misplacement of instrumentation. Follow up ranged from 2 weeks to 24months mean 8 months None of the patients required revision surgery due to instability. VAS improvement at latest follow up was in average 2 points. Conclusion: Our case series results showed a trend in favor of the hypothesis that a single level MIS fusion with an additional tubular decompression is a safe alternative for longer more rigid constructs. These findings corroborate the results from e recent biomechanical study. Longer follow up studies and a larger sample may be needed in order to drive final conclusions regarding the long-term benefits when compared with longer instrumentations.

P264 - Endospine Plus For Minimally Invasive Endoscopic Spinal Surgeries

Anshul Gupta¹

¹Department of Neurosurgery, Sir Ganga Ram Hospital, New Delhi - India

Introduction: Lumbar prolapsed intervertebral disc (PIVD) and lumbar canal stenosis (LCS) are well described pathological conditions which typically result from degeneration and spondylosis. Traditionally, these lumbar pathologies are treated with an open decompressive laminectomy / foraminotomy / discectomy, with or without facetectomies. We performed the minimal invasive technique for treating these pathologies using an indigenously modified endoscopic sheath “Endospine plus” in 200 patients in a span of 5 years and analyzed the results and outcome of the procedure. Material and Methods: A total of 200 patients suffering from lumbar prolapsed intervertebral disc or canal stenosis were treated using “Endospine plus” sheath and evaluated. Pre-operative pain assessment was done according to the Visual Analogue scale. Surgical procedure was conducted after obtaining an informed consent from the patients. The findings along with operative details were recorded and post-operative morbidity, complications and clinical outcome were noted. Follow up of the patients was done at one week, one month, 3 months and 6 months and results were analyzed according to the “Modified Macnab’s criteria”. Results: Of the total 200 patients, 133 suffered from disc disease and rest 67 had canal stenosis. Most common symptom in both groups was sciatica. L5-S1 level was most common in PIVD and L4-5 level was the most common level involved in LCS. There was a statistically significant difference between the pre-operative and post-operative visual analogue scale. Dural tear was the most common complication associated with the procedure. Outcome after 6 months was excellent/good in 92.5% with 5.5% fair and 2% poor outcome in PIVD group and excellent /good in 80%, fair in 11.5% and poor in 8.5% in the LCS group. Conclusion: Endoscopy provided wide visualization and minimal tissue disruption for both type of pathologies. It allowed bilateral decompression via a unilateral approach for LCS, thereby preserving the contralateral ligaments and musculature. This lead to decreased post-operative morbidity and early recovery and discharge from the hospital. Also with significant reduction in post-operative pain as assessed via VAS and excellent to good outcome in majority of the patients, endoscopic discectomy and spinal decompression using “Endospine plus” is a new minimally invasive technique which is upcoming and can be considered an effective alternative to the conventional open surgery for prolapsed intervertebral disc and lumbar canal stenosis.

P265 - Minimally Invasive Resection Of Extradural Dumbbell Tumors Of Thoracic Spine

YuTong Gu¹

¹Department of Orthopaedics, Zhongshan Hospital of Fudan University, Shanghai - China

Introduction: The Dumbbell-shaped thoracic tumors represent a distinct type of tumor and involve in both the spinal canal and the posterior thoracic cavity. Successful treatment for the tumors depends on gross total resection (GTR) via an open laminectomy and facetectomy or transthoracic transpleural approach. However, these operations have significant morbidity related to the surgical approach, potential blood loss, or extensive dissection. In this study, we report our experiments with minimally invasive method for the removal of extradural dumbbell thoracic tumor and evaluate the feasibility, efficacy and safety of this technique. Materials and Methods: We retrospectively reviewed 15 patients with dumbbell-shaped thoracic tumors who underwent minimally invasive resection and unilateral transforaminal thoracic intervertebral fusion (TTIF) through unilateral paraspinal muscle approach with an expandable tubular retractor from December 2013 to May 2014. The mean age was 41.3 years (range, 18-53 years). Clinical data, and tumor characteristics were analyzed. The pain intensity in the previously symptomatic region was graded with VAS. The severity of the neurologic deficit was assessed by using the ASIA impairment scale before and after surgery. The radiological outcomes were evaluated according to the change of bone bridging, the radiolucency, the instability and the disc height. Results: All patients underwent successful minimally invasive treatment of their spinal neoplasms. There were no procedure-related complications. The efficacy in terms of neurological recovery, pain improvement and operative variables (length of incision, operative duration, blood loss, and hospital stay) was better when compared with prior published studies. Postoperative CT image demonstrated complete resection of dumbbell tumor in the patients. The solid fusion was obtained after 3 months follow-up and there was no failure of internal fixation. Conclusions: If the medial border of intracanal component of extradural dumbbell tumor is near the midline of canal and the pedicles of adjacent vertebrae to tumor are intact, minimally invasive resection of tumor through unilateral paraspinal muscle approach combined with unilateral TTIF is good choice.

P266 - a prospective randomized comparative study of minimally invasive spinal decompression surgery using arthroscopy (biportal technique) vs. Microscopy

SiYoung Park¹, TaeWook Kang¹, Seungwoo Suh¹

¹Department of Orthopaedic Surgery, Korea University, Seoul - Korea

Introduction: Lumbar laminectomy and discectomy is a standard surgical technique for lumbar radiculopathy due to disc herniation. Many new surgical techniques have been introduced from open surgery to percutaneous procedures. Minimally invasive surgical techniques are preferred because of less postoperative pain and shorter hospital stay. However, there have been many controversies about success rate of percutaneous techniques. The object of this study was to assess the feasibility of spinal surgery using arthroscope compared with microscope. Material and Methods: 62 patients undergoing laminectomy and discectomy were included. Randomized two groups, arthroscope group (AG) and microscope group (MG) were dividing random number table. All surgery were performed as routine partial laminectomy and discectomy by one surgeon. Perioperative data and clinical outcomes at postoperative 6 months were collected and analyzed. Results: Demographic data, level of surgery were comparable between two groups. Shorter operation time and less pain at first day after surgery were recorded in AG. There were no significant differences in clinical outcomes comparing micorscopic surgery. A favorable clinical outcomes were shown at 6 months after surgery in both groups. Conclusion: Lumbar laminectomy and discectomy using arthroscopy showed favorable clinical outcomes, less pain and shorter hospital stay compared surgery using microscope.

P267 - Endoscopic Decompressive Surgery For Lumbar Spinal Stenosis: Analysis Of Clinical Outcome And Predictive Factors

Azizul Akram Salim¹

¹Department of Orthopaedic, Universiti Sains Malaysia, Kubang Kerian - Malaysia

Introduction: Endoscopic approach is one of the approaches that maintained the aim of surgery while minimize the collateral tissue destruction. Its efficacy and safety have been advocated by numerous studies. To our knowledge, there are number of studies done for lumbar stenosis with regards to the outcome and related issues in endoscopic spine surgery, however there are lacked of literature that evaluate the outcome of the endoscopic decompressive lumbar spine surgery Material and Methods: Between 2009 and 2013, 60 eligible patients who undergone endoscopic interlaminar decompressive spine surgery (Destandau’s method) for lumbar degenerative spinal stenosis in Hospital Universiti Sains Malaysia were selected for the study. The surgery was done by 2 experienced endospine surgeon. The clinical outcome was measured pre and post-operative for Visual Analogue Scale (VAS) for back and leg pain, motor grading, sensory, Oswestry Disability Index (ODI), and MacNab’s criteria. The cohort was group into two categories: excellent to good result was grouped into favourable category and fair to poor result was grouped into unfavourable category. Paired t-test and Fisher exact test was used for statistical analysis Results: The mean age of patients were 60.82 years old. The mean follow-up period was 30.1 months (range 17.2 to 43 months). There were 23 (38.3%) male and 37 (61.7%) female. The mean operation time was 183.6 minutes (ranging from 124.8 minutes to 242.4 minutes). Mean blood loss was 150.18 ml (ranging from 30.82 ml to 269.54 ml). Post-operative hospital stay mean was 2.45 days (ranging from 1.34 days to 3.56 days). Most frequently involved level were L4/L5 in 51 patients (52.6%), followed by L3/L4 in 19 patients (19.6%), L5/S1 in 24 patients (24.7%), and L2/L3 in 3 patients (3.1%). VAS for back pain and leg pain and ODI for pre and post operation was statistically significant (p < 0.001). Reduction in neurology is statistically insignificant. Based on Macnab’s criteria, 88.4% showed excellent to good outcome and 11.7% showed fair outcome. There was no significant predicitive factor for the outcome of surgery. As for complication, 13.3% of patients had dural tear; 1.6% had nerve root injury, wrong level and delay wound healing; 11.6% had leg dysesthesia; 11.6% had recurrent stenosis; and 1.6% and 6.6% had reduced motor and sensory respectively. Conclusion: Endoscopic decompressive lumbar stenosis surgery is a safe surgery. It has an excellent outcome as comparison with the conventional open decompression technique. Hence, it has advantages in term of maintaining the motion segment of spine and its posterior stabilizer, reducing the back and leg pain, and improve quality of life beside a shorter hospital stay and early mobilization.

P268 - Learning Curve Of Minimally Invasive Oblique Lateral Lumbar Interbody Fusion: Single Surgeon’s Experience Of 57 Consecutive Cases

Jung-Woo Hur¹, Kyeong-Sik Ryu¹, Jin-Sung Kim¹

¹Seoul St. Mary’s hospital, Seoul - Korea, Republic

Introduction: Minimally invasive oblique lateral lumbar interbody fusion (MIS-OLIF) using a tubular retractor and pre-psoas approach has recently been gaining popularity because of its potential for minimizing para-spinal muscle damage and reducing recovery time. However, the published literature has not characterized the surgeon’s learning curve with the technically demanding technique of a MIS-OLIF. The purpose of this study is to define and analyze the learning curve for MIS-OLIF with a single spine surgeon’s experience based on intra- and perioperative parameters. This study is retrospective analysis of single surgeon’s consecutive case series in a single institution Material and Methods: Fifty-seven consecutive patients with single or multi-level degenerative lumbar diseases who were treated by MIS-OLIF were included in the study. Surgeries were performed using oblique pre-psoas approach with a tubular retractor, and a cage was inserted using an orthogonal maneuver by a single surgeon. The corresponding segments were fixed with additional percutaneous pedicle screws. MIS-OLIF without posterior decompression was performed in 33 cases and MIS-OLIF plus posterior decompression was performed in 24 cases. Corrected operative time per level, operative blood loss, postoperative drainage, transfusion rate, and ambulation recovery time were measured. Intraoperative and postoperative complication incidences were also identified. Clinical results were assessed using the visual analogue scale (VAS). The learning curve was assessed using a logarithmic curve-fit regression analysis. In the single-level OLIF group (n = 21), 12 patients were defined as the “early” group (among the first 30 cases of the series), and the subsequent 9 cases were defined as the “late” group for comparison. Results: Corrected operative time gradually decreased as the series progressed, and an asymptote was reached after about 30 cases. Average VAS scores for lower back pain and radiating pain also significantly decreased from an average of 6.9 to 3.8 and 7.6 to 2.5, respectively. In the single-level OLIF series, operative time was significantly shorter in the late group (99 ± 54 min) than the early group (141 ± 21 min), and blood loss during the operation was significantly reduced in the late group (482 ± 269 mL) compared with the early group (542 ± 157 mL). Ambulation recovery time and VAS scores for back and leg pain did not differ between the two groups. There were two cases of retroperitoneal hematoma in the early second group requiring revision surgeries. Conclusion: The MIS-OLIF is a technically difficult procedure to the practicing spine surgeon with regard to unfamiliar retroperitoneal approach. Although it is not easy to master this minimally invasive technique, Operative time and blood loss improved with the surgeon’s experience. After the initial learning curve, this technique could be an effective and reliable option for the surgical treatment of lumbar degenerative disease. Further studies are warranted to delineate the methods to minimize the complications associated with the learning curve.

P269 - Percutaneous Instrumentation Plus Mini-Opening for the Treatment of Thoracolumbar Fractures. August 2015 to August 2017. Hospital Santo Tomás, Panamá

Alvino De Leon¹, Jose Hermida¹, Juan Altafulla¹

¹Department of Neurosurgery, Hospital Santo Tomás, Panama - Panama

Introduction: Hospital Santo Tomás is the most important trauma center in Panamá. Spine trauma is common and represent one of the main causes of disability. Thoracolumbar fractures is traditionally treated by open instrumentation and fusion. In recent years minimally invasive spine instrumentation surgery has emerged as a tool for the treatment of many spine disorder because it reduces postoperative pain, blood loss and quicker recovery times therefore leading to decrease length of stay. In this case study we present our data in the treatment thoracolumbar trauma . Materials and Methods: 113 patients were included . All were first evaluated and admitted thru the emergency department. All patients were male. The average age was 22. None of the patients present comorbidities. The trauma mechanics were motor vehicle accidents (57%), falls (22%) and been hit by a car (21%). The patient's neurological evaluation present as follow: Asia A 15% Asia B 34% Asia C 23% Asia D 12% Asia E16%. The affected leves were T11 9%, T12 9%, L1 11%, L2 12%, L3 9%, L4 21% and L5 22%. We use the AOSpine thoracolumbar fracture classification. Most of the Fractures were A3 and A4 but we also include B Fractures.

After proper work up and informed consent was signed the patients were taken the OR. Antibiotics were apply one hour prior to the procedure. Under general anesthesia the patient went to prone position and rolls were allocated under the thorax and abdomen. Alcohol plus chlorhexidine was apply twice. Sterile drapes were apply. The fluoroscopy is brought in and the affected leves identified. From the site of the fracture two leves up and two leves down were operated and the instrumentation was extended if it ended at T11 or L5. In AP views the pedicles are located and in the external border the skin is marked. Approximately 2.5 cm skin wound is performed and through an standard technique the screws are inserted and united by a posterior bar. At the site of the fracture the fascia is open and a standard laminectomy is preform. The retropulsion fragment is ether push forward or a transpedicular osteotomy is preformed and the fragment is remove. We did not use bone matrix or bone surrogates. All patients were treated with sodium hypochlorite. The patient is then evaluated by a physical therapy physician and discharge in the first 48 hours. Results: The follow up period it is up a year. 16 patients were lost in the follow up. Three of this patients died for unrelated causes. The blood loss was minimally. The kyphosis was reduced with this approach. Most patients required only one drug for pain control. No patients had worsened of symptoms in the post op period. Only 3% of the ASIA A went to B but 39% of the ASIA B went to become ASIA C or D specially those how had two point discrimination. No ASIA B or C became A. 3 patients presented one month later for spondilodiscitis and were treated accordingly. 9 patients present with post surgical kyphosis and needed a second surgery all of them went to an open procedure and fusion. 6 patients had a failed back syndrome and went to persist with axial pain although the mri and electromyography were normal. One patient had screw extrusion and had to be remove. Conclusions: Minimally invasive technique represent an option for the thoracolumbar fractures. Post op kyphosis and instrumentation extrusion is similar to the conventional treatment.

P270 - Spinal Stenosis Decompression By Percutaneous Endoscopic Intervertebral Decompression Under Local Anesthesia And Outpatient Surgery Setting -Case Series, Preliminary Results And Literature Review

Ting Chun Huang¹

¹National Taiwan University Hospital Chu-Tung Branch, Hsinchu County - Taiwan, Province of China

Introduction: The necessity of fusion for spinal stenosis has been questioned [2]. Decompression become the main stay of treatment for spinal stenosis. PELD through transforaminal approach for lateral recess stenosis was proved to be effective.[3] Interlaminar approach of PELD had little reports; however, similar approach of MED was will established in terms of unilateral laminectomy and bilateral decompression (ULBD).[1] This research is to proposed PELD through interlaminar approach for spinal stenosis treatment. Material and Methods: Prospective non-randomised case series of 30 cases from single hospital by single surgeon (author) from 2016/07 to 2018/05. Preoperational and post operational MRI CT were conducted to verify the area of decompression. SF-36, JOA score and ODI were recorded preoperatively and postoperatively(immediate postop, 1 month, 3 month and 6 months). Patients was under local anesthesia (2%Xylocaine injected around the incision and through the surgical wound. No sedation was used and heart rate and blood pressure was controlled with IV medications. Unilateral laminotomy and bilateral decompression were done with endoscopic high speed burr and endoscopic instruments such as Kerrison through single portal. Hemostasis was done with endoscopic electrocautery and IV transamine and no drain was inserted. Patients was discharged one hour after surgery. Non-parametric statistical methods were applied(Mann-Whitney U test). Postop decompression area was compared with using 3D CT reconstruction and imaging registering software. Results: SF-36, JOA score and ODI all revealed significant differences comparing preoperatively and postoperatively conditions(Mann-Whitney U test). Bleeding and operation time were comparable to literature.[4] Complications of asymptomatic minimal dural tear were noted on one PEID case. Surgical time shorten by half on the fourth case of PEID (70min/ level) (Video will be showed during presentation). Surgical time was analyzed by dividing the video into bony procedures(laminotomy), hemostasis, ligamentum flavum removal. Bleeding was minimal. Conclusion: Unilateral laminotomy and bilateral decompression is a well established surgical method for spinal stenosis. Using percutaneous endoscopy with endoscopic high speed burr to perform it under local anesthesia is a novel and breaking through approach with acceptable results.

P271 - Comparing Decompression Effects Of Spinal Stenosis Treated By Percutaneous Endoscopic Lumbar Discectomy Through Transforaminal Versus Intervertebral Approach Under Local Anesthesia And Outpatient Surgery Setting-Case Series, Preliminary Results And Literature Review

Ting Chun Huang¹

¹National Taiwan University Hospital Chu-Tung Branch, Hsinchu County - Taiwan, Province of China

Introduction: The necessity of fusion for spinal stenosis has been questioned [2]. Decompression become the main stay of treatment for spinal stenosis. PELD through transforaminal approach for lateral recess stenosis was proved to be effective.[3] Interlaminar approach of PELD for spinal stenosis had little reports. It is challenging to decide whether transforaminal approach or interlaminar approach to utilize for individual spinal stenotic patients. This research is to analyze decompression effects of two approaches imagewise and functionwise. Material and Methods: Prospective non-randomized spinal stenosis with radiculopathy or claudication case series of 30 cases of PETD(PELD via transforaminal approach) and 30 cases of PEID (PELD via interlaminar approach) for spinal stenosis with unilateral/ bilateral radiculopathy from single hospital by single surgeon (author) from 2016/07 to 2018/05. Preoperational and post operational MRI CT were conducted to verify the area of decompression. SF-36, JOA score and ODI were recorded preoperatively and postoperatively (immediate postop, 1 month, 3 month and 6 months). Patients was under local anesthesia (2%Xylocaine). No sedation was used and heart rate and blood pressure was controlled with IV medications. Endoscopic high speed burr was used only in PEID and endoscopic instruments such as Kerrison through single portal were utilized in both approaches. Hemostasis was done with endoscopic electrocautery and IV transamine and no drain was inserted. Patients was discharged one hour after surgery. Non-parametric statistical methods were applied(Mann-Whitney U test). Postop decompression area was compared with using 3D CT reconstruction and imaging registering software. Results: SF-36, JOA score and ODI revealed no significant differences comparing both approach with unilateral radiculopathy; however, interlaminar approach has significant results for bilateral radiculopathy(Mann-Whitney U test) . Bleeding and operation time were comparable for both approaches and to literature.[4] Surgical time was analyzed by dividing the video into bony procedures(foraminoplasty or laminotomy), hemostasis, ligamentum flavum removal and annuloplasty. Surgical time was significant shorter for transforaminal approach (40min/ level) than interlaminar approach (70 min/ level). Complications of asymptomatic minimal dural tear were noted on one PETD case and one PEID case. Decompression area (3D and 2D) data was pending. Preliminary data revealed transforaminal appoach could decompressed foramen and lateral recess lateral to inner side of pedicle within the endoscopic trajectories; however, interlaminar approach could decompressed the ligaventum flavum from origin to superior lamina of next vertebra and could decompress to inner side of pedicle and to foramen. Concluson: Case series has its limitation of no control group and its subject to bias. Limited followup time was also need improvements. For both approaches, preoperative 3D planning utilizing 3 views of MRI(coronal, sagittal and axial views) was the key points for relieving patient’s symptoms and the accessibility of pathologies. For unilateral radiculopathy caused by lateral recess stenosis, posterior epidural space were not severely stenotic and both approaches could accomplish adequate decompression for lateral recess and foramen. For bilateral radiculopathy caused by central stenosis, interlaminar approach could decompressed posterior epidural space adequately but transforaminal approaches could not. (Videos could be showed during presentation).

P272 - Adjacent Segment Disease Treated By Percutaneous Endoscopic Lumbar Decompression Via Interlaminar Approach Under Local Anesthesia, Preliminary Results And Literature Review

Ting Chun Huang¹

¹National Taiwan University Hospital Chu-Tung Branch, Hsinchu County - Taiwan, Province of China

Introduction: Adjacent segment disease (ASD) occur in 30% of lumbar fusion surgery and annual incidence is 2-3%.[2] The most effective treatmen for ASD has not yet been determined. Fusion does not necessarily improve surgical outcome in primary spondylolisthesis.[1] Decompression only for ASD patient without mechanical back pain or manageable by pain intervention is rarely reported. There has been reports that transforaminal approach has 2 years of survival rate of near 70%. [5]Preventive decompression for those with stable facet orientation has been reported to be effective for 84% of the patients.[3] This study is aimed to study decompression with percutaneous endoscopic lumbar decompression through interlaminar approach for ASD treatment. Material and Methods: Prospective non-randomised case series of 5 cases of adjacent segement disease from single hospital by single surgeon (author) from 2016/07 to 2018/05. Preoperational and post operational MRI CT were conducted to verify the area of decompression. SF-36, JOA score and ODI were recorded preoperatively and postoperatively(immediate postop, 1 month, 3 month and 6 months). Patients was under local anesthesia (2%Xylocaine injected around the incision and through the surgical wound. No sedation was used and heart rate and blood pressure was controlled with IV medications. Unilateral laminotomy and bilateral decompression were done with endoscopic high speed burr and endoscopic instruments such as Kerrison through single portal. Hemostasis was done with endoscopic electrocautery and IV transamine and no drain was inserted. Patients was discharged one hour after surgery. Non-parametric statistical methods were applied(Mann-Whitney U test). Postop decompression area was compared with using 3D CT reconstruction and imaging registering software. Results: SF-36, JOA score and ODI all revealed significant differences comparing preoperatively and postoperatively conditions(Mann-Whitney U test) . Bleeding and operation time were comparable to literature.[4] Complications of asymptomatic minimal dural tear were noted on one PEID case. Surgical time shorten by half on the fourth case of PEID (70min/ level) (Video will be showed during presentation). Surgical time was analyzed by dividing the video into bony procedures(laminotomy), hemostasis, ligamentum flavum removal. Bleeding was minimal. Conclusion: Careful selection of ASD patient with spinal stenosis without instabilities could warrant decompression only as a treatment of choice as long as no further iatrogenic instabilities are created. Percutaneous endoscopic lumbar decompression via interlaminar approach may be a treatment option for this indication on the advantage of no general anesthesia burden, less further soft tissue damage and a shorter recovery.

1. Forsth P, Olafsson G, Carlsson T, Frost A, Borgstrom F, Fritzell P, Ohagen P, Michaelsson K, Sanden B. A Randomized, Controlled Trial of Fusion Surgery for Lumbar Spinal Stenosis. N Engl J Med. 2016;374:1413-1423.

2. Harrop JS, Youssef Ja Fau - Maltenfort M, Maltenfort M Fau - Vorwald P, Vorwald P Fau - Jabbour P, Jabbour P Fau - Bono CM, Bono Cm Fau - Goldfarb N, Goldfarb N Fau - Vaccaro AR, Vaccaro Ar Fau - Hilibrand AS, Hilibrand AS. Lumbar adjacent segment degeneration and disease after arthrodesis and total disc arthroplasty.

3. Hikata T, Kamata M Fau - Furukawa M, Furukawa M. Risk factors for adjacent segment disease after posterior lumbar interbody fusion and efficacy of simultaneous decompression surgery for symptomatic adjacent segment disease.

4. Liu X, Yuan S, Tian Y. Modified unilateral laminotomy for bilateral decompression for lumbar spinal stenosis: technical note. Spine. 2013;38: E732-737.

5. Telfeian AE. Transforaminal Endoscopic Surgery for Adjacent Segment Disease After Lumbar Fusion.

P273 - PLIF With Stand-alone Titanium Cages

Seishi Matsui¹, Seiji Shigekawa¹, Takeharu Kunieda¹

¹Department of Neurosurgery, Ehime University School of Medicine, To-on - Japan

Introduction: The purpose of this study was to determine the clinical and radiographic outcomes in patients treated for degenerative lumbar spine disease with a posterior lumbar interbody fusion (PLIF), using stand-alone box-shaped titanium cages. Material and Methods: The 41 patients comprised 14 males and 27 females, aged 29-81 years (mean 64). All patients complained lumbago and/or pain of lower extremities. 29 patients had lumbar spondylolisthesis (grade 1), 8 had intervertebral foraminal stenosis, and 4 had lumbar canal stenosis. All patients underwent lamina fenestration and stand-alone PLIF, with minimum or no medial facetectomy. PLIF for 1 level was in 35 patients, and 2 levels in 6. 20 patients had posterior decompression in other lumbar levels simultaneously at surgery. Postoperative follow up period was more than 2 years (mean 46 months). Clinical outcomes were measured using JOA score (max. 15 pts). X-ray radiographs were used to evaluate fusion, that was defined as the absence of segmental instability on flexion–extension, and adjacent segment degeneration as newly developed/enlarged osteophyte or narrowing disc height. Results: JOA score was improved from 7.9 ± 2.2 to 13.6 ± 1.5 while early cage migration was seen in 5 patients. Of these 5 patients, 2 became symptomatic and required revision surgery . In 39 patients who did not undergo reoperation, the fusion rate was 4.4% at 1 year, 40% at 2 year, and 64.4% at final follow up, and no adjacent segment degeneration was observed. Conclusion: PLIF with stand-alone box-shaped titanium cage, preserving facet joints, showed low fusion rate. However it can provide good clinical outcome and decrease the incidence of postoperative adjacent segment degeneration.

P274 - Cortical Bone Trajectory Screws For Posterior Lumbar Interbody Fusion: Our First 100 Cases

Nicola Marengo¹, Fabio Cofano¹, Salvatore Petrone¹, Marco Ajello¹, Paolo Pacca¹, Francesco Zenga¹, Diego Garbossa¹, Alessandro Ducati¹

¹Departement of Neuroscience, Neurosurgery, University of Turin, Turin - Italy

Introduction: The use of cortical bone trajectory (CBT) pedicle screws for circumferential interbody fusion first described in 2009 now represents a viable alternative for single level procedure with reduced invasiveness and less tissue destruction than the traditional technique. In addition, CBT screws have a potentially stronger pull-out strength because of the greater amount of cortical bone intercepted. Only few series exist evaluating clinical and radiological outcomes of CBT screws. Material and Methods: We retrospectively reviewed all patients that underwent a posterior lumbar interbody fusion (PLIF) with CBT screws. We evaluated patient demographics, clinical outcome with VAS scale and ODI index, radiological data such as fusion, lordosis and muscle trauma (Multifidus cross sectional area – MF-CSA before and after the procedure), operative blood loss, hospital stay, use of fluoroscopy and postoperative complications. Results: A total of 100 patients undergoing CBT-PLIF for degenerative lumbo-sacral disease were reviewed. 60 were male, 40 were female, from April 2014 to March 2017. 21 of them (21%) had previous lumbar spine surgery. Mean surgical time was 2,9 hours. Mean operative blood loss was 282 ml and x-rays dose per procedure was 1,60 mGcm². Mean length of stay was 3,3 days. Mean follow-up time was 12,3 months. Mean MF-CSA % change was 16%. For each level a mean lordosis of 9,8° was measured after the procedure. Fusion was highlighted in 92 patients at 12 months (92%). There were 4 complications in 3 patients (4%): 3 misplaced screws were observed and one wound infection. Mean ODI index improved from 51 to 21, whereas mean VAS data showed an improvement from 8,2 to 3,1. Conclusion: This is one the largest study worldwide about CBT-PLIF. Results underlined the safety of this technique and the promising clinical and radiological outcomes that will need a longer follow-up.

P275 - Ten-Step Minimally Invasive Cervical Laminectomy Via A Unilateral Tubular Approach: Technical Note And Early Clinical Experience

R. Nick Hernandez¹, Rodrigo Navarro-Ramirez¹, Sergio Soriano-Solis², Christoph Wipplinger¹, Roger Hartl¹, Jose-Antonio Soriano-Sanchez²

¹Department of Neurosurgery, New York-Presbyterian/Weill Cornell Medicine, New York - United States ²Soriano Institute of Minimally Invasive Spine Surgery, ABC Hospital, Neurological Center, Sante Fe Campus, Mexico City - Mexico

Introduction: Minimally invasive spine surgery (MISS) utilizing tubular retractors has become an increasingly popular approach to the spinal column. The concept of a unilateral approach for bilateral decompression, first applied in the lumbar spine, has recently been applied to the cervical spine. However, a better understanding of the indications and surgical techniques is required to effectively educate surgeons on how to appropriately perform tubular laminectomy via a unilateral approach in the cervical spine to facilitate safe and successful surgery. We therefore describe a ten-step approach for minimally invasive cervical laminectomy via a unilateral, tubular approach and report our early clinical experience. Materials and Methods: We reviewed our experience between 2008 and 2017 to develop a ten-step description of the surgical techniques for performance of a minimally invasive cervical laminectomy via a unilateral tubular approach in patients with cervical spondylotic myelopathy. We identified 15 patients (9 males, 6 females) who were treated with this approach. Visual analog score (VAS) and neck disability index (NDI) were obtained pre- and post-operatively. Results: The mean age of the 15 patients was 73.1 ± 6.8 years (range 64-85 years). The median number of levels treated was 1 (range 1-3). Mean operative time was 125.1 ± 30.9 minutes, or 87.8 ± 19.7 minutes per level. Mean estimated blood loss was 57.3 ± 24.6 cc. No complications were encountered. Median follow-up was 15 months (range 3-48 months). Mean pre- and post-operative VAS were 6.4 ± 2.4 and 1.0 ± 0.8, respectively (p < 0.001). Mean pre- and post-operative NDI were 46.4 ± 19.2 and 7.0 ± 6.9, respectively (p < 0.001). Key technical points include drilling no more than 50% of the medial, ipsilateral facet, constant attention to the avoidance of downward pressure on the cervical spinal cord, “wanding” the tubular retractor medially to perform an “over-the-top” contralateral laminectomy using the ligamentum flavum (LF) as a protective layer, identifying the cranial and caudal borders of the LF, and use of a ball-tip probe or blunt hook to create a dissection plane between LF and cervical dura prior to LF resection. Conclusion: In our early clinical experience, minimally invasive cervical laminectomy via a unilateral tubular approach is safe and effective. Adherence to the presented ten-step description of this procedure will allow surgeons to effectively address bilateral cervical pathology while preserving stability and minimizing complications.

P276 - Microinvasive Midline Decompression And Interbody Fusion For Lumbar Degenerative Diseases

Zan Chen¹, Zhenlei Liu¹

¹Department of Neurosurgery, Xuanwu Hospital, Capital Medical University, Beijing - China

Introduction: With an aging population, lumbar degenerative diseases have become the most common indication for spine surgery in patients over 65 year old [1]. Cortical Bone Trajectory (CBT) screw was introduced in 2009 to better solve the complications caused by low bone quality following spine instrumentation surgery [2]. Here we present a preliminary result of a prospective observational study to evaluate the effectiveness and safety of microinvasive midline decompression and interbody fusion for lumbar degenerative diseases. Methods: Patients with lumbar degenerative diseases treated with midline decompression and interbody fusion combined with posterior fusion with CBT screw between Dec. 2016 and Feb. 2017 were enrolled. All the patients manifested bilateral lower limb neurogenic claudication. Perioperative data including demographics, symptom severity (Japanese Orthopedics Association (JOA) scale, Visual Analog Scale (VAS) scale), walking ability, operation time, blood loss, hospital stay and complications was collected. Results: 32 patients were included (19 male and 13 female, mean age 68.5 ± 11.2 year old). Claudication presented for 2.5 ± 1.2 years because of lumbar spinal stenosis (28 cases, 23 of which comorbid with L4/5 spondylolisthesis) and lumbar disc herniation (4 cases). Preoperative JOA and VAS were 10.5 ± 3.5 and 7.5 ± 1.2, respectively. Patients could walk 280.5 ± 105.3 meters without claudication (claudication distance) preoperatively. All patients underwent midline decompression, lumbar interbody fusion (64 interbody cages) and posterior fusion with CBT screws (132 screws with a diameter of 5.0 mm and length of 35 mm) with intraoperative navigation. Operation time, blood loss and incision length were 2.6 ± 0.5 hours, 106.5 ± 25.5 ml and 3.2 ± 0.5 cm, respectively, for single level procedures. Patients were recommended to ambulate 3 days postoperatively with a lumbar brace for 3 months. The mean hospital stay was 3.5 ± 2.5 days. One month postoperatively, the JOA, VAS and claudication distance were 14.5 ± 2.5, 4.2 ± 1.5 and 550.5 ± 280.6 meters, respectively. One patient suffered from radicular pain caused by L5 spondylolysis following CBT screw insertion. Revision was performed and the patient’s symptom was completely relieved. No other complications, like wound infection, epidural hematoma, nerve root injury, deep vein thrombosis or pulmonary embolism, happened. Conclusion: Midline decompression and interbody fusion combined with CBT posterior fusion is efficacious and safe for the management of lumbar degenerative diseases for short term. The long term results remain to be validated. Proper attention should be paid to avoid bone complications like spondylolysis during implantation of CBT screws.

P277 - Posterior Lumbar Interbody Fusion With 3D-Navigation Guided Cortical Bone Trajectory Screws For L4/5 Degenerative Spondylolisthesis: 1-Year Clinical And Radiographic Outcomes

Ibrahim Hussain¹, Michael Virk¹, Thomas Link¹, Apostolos Tsiouris², Eric Elowitz¹

¹Department of Neurological Surgery, Weill Cornell Medical Center-New York Presbyterian Hospital, New York - United States ²Department of Neuroradiology, Weill Cornell Medical Center - New York-Presbyterian Hospital, New York - United States

Introduction: Posterior lumbar interbody fusion (PLIF) with traditional trajectory pedicle screws is a time-tested treatment for degenerative spondylolisthesis. However, retraction of neural elements required during the procedure can result in new neurologic dysfunction and cerebrospinal fluid leak in 7-10% of cases. Intraoperative blood loss can range from 400-800 mL and average hospital stays are as long as 10 days in some studies. PLIF with cortical bone trajectory screws (PLIF-CBT) serves as a minimally-invasive alternative. This technique uses a more inferomedial entry point and superolateral trajectory, thus requiring a smaller incision and less tissue dissection. Less thecal sac retraction is necessary due to narrower interbody cages. Also due to bicortical purchase, these screws have increased uniaxial pullout strength compared to traditional trajectory pedicle screws. Our objective was to determine the clinical and radiographic outcomes of PLIF-CBT at a minimum of one year postoperatively at our institution. Materials and Methods: Patients undergoing PLIF-CBT utilizing an intraoperative CT scanner and 3D-navigation guidance system for grades 1 or 2 L4/5 degenerative spondylolisthesis between February 2015 and May 2016 were included. Demographic, intraoperative, and perioperative data were collected. Pre- and post-operative pain and disability questionnaires were prospectively collected and retrospectively analyzed using back and leg pain visual analog scores (VAS) and the Oswestry Disability Index (ODI). Follow-up questionnaires and CT imaging were obtained at a minimum of one year postoperatively. Fusion status was rated as 0 (no fusion), 1 (partial), or 2 (complete), with scores 1 and 2 considered definitively fused. Paired t-test for used for statistical analysis with P-values less than 0.05 considered significant. Results: 18 (13 females) met inclusion criteria. The average age and BMI at the time of surgery was 67.2 years old and 28.9 kg/m², respectively. Average blood loss, operative time, and hospital length of stay were 161.67 mL, 219.67 minutes, and 2.4 days, respectively. The average back pain VAS improved significantly from 5.82 preoperatively to 1.53 postoperatively (P = 0.0025). The average combined bilateral buttock and leg pain VAS improved significantly from 20.65 preoperatively to 2.0 postoperatively (P < 0.0001). The average ODI also improved significantly, from 40.35 to 11.47 (P < 0.0001). The overall fusion rate at an average of 14.9 months was 37.5% (25% complete; 12.5% partial). There were no instances of intraoperative or postoperative complications and no patient required subsequent interventions during the study period. Conclusion: PLIF-CBT can be performed safely and reproducibly using iCT-based 3D-navaigation image guidance for grades 1 or 2 L4/5 degenerative spondylolisthesis. The low complication profile while decreasing intraoperative blood loss and hospital length of stays reveals this procedure to be superior to PLIF with traditional pedicle screws. At one year postoperatively, patients experienced statistically significant reductions in back pain, leg pain, and disability, and none required subsequent interventions. Fusion rates at an average of 15 months postoperatively were unexpectedly low at 37.5%, however did not correlate with clinical outcomes. A larger cohort and longer time point for clinical/radiographic follow-up is required to more accurately capture the durability of this procedure compared with other lumbar interbody fusion techniques.

P278 - Technical Note: The Use Of 2 Microscopes For Multilevel El Lumbar Spinal Stenosis Decompression Using The “Slalom Technique”

Christoph Wipplinger¹, Eliana Kim¹, Rodrigo Navarro-Ramirez¹, R. Nick Hernandez¹, Carolin Melcher¹, Michelle Paolicelli¹, Farah Maryam¹, Roger Härtl¹

¹Department of Neurological Surgery, Weill Cornell Medicine, New York - United States

Introduction: Lumbar stenosis can be effectively treated using tubular “over the top” decompression. For multilevel stenosis, a bilateral multi-segmental microsurgical decompression through separate, alternating cross-over approaches has been described and is referred to as the “slalom technique”. Longer operation and thus greater anesthesia times with multilevel surgery are associated with higher perioperative complication rates. We introduced the use of two microscopes in order to reduce operative time. Here, we present our step-by-step guide and perioperative outcome data using two microscopes simultaneously. Material and Methods: We collected data on 13 patients, suffering from multilevel symptomatic lumbar spinal stenosis, operated at our institution between 2015-2016 in which we performed our “Slalom Laminectomy Technique”. These patients were compared to a group of 18 patients who underwent a MIS tubular laminectomy using one microscope. We assessed surgical time (ST) per operated level, estimated blood loss (EBL) per level, perioperative complications and revision surgeries. All surgeries were performed in the same fashion by two neurosurgeons. For L3-L5 stenosis; the surgeon sets the incision at L4/5, while the other surgeon stands opposite and sets the incision at L3/4. It is critical to set the incision at L4/5 as lateral as possible to provide enough space for both microscopes. 18 mm tubular retractors are used for retraction. Subsequent steps are carried out simultaneously by two surgeons using two microscopes according to our previously published 10 step technique (Operative Neurosurgery, 2016). Results: The mean age of the patients was 68 years ± 8. The ST per level was 68 min ± 19 in the Slalom (S) group vs. 89min ± 26 (p < 0.05) in the single microscope group (C) with an EBL per level of 39ml ± 30 (S) vs. 44 ml ± 24(C). We had no intraoperative complications and none of our patients required a revision surgery during a mean follow-up of 12 months. Conclusion: Our case series showed that the simultaneous use of two microscopes is feasible and can be performed safely for multi-segmental lumbar spinal stenosis with significantly shorter surgical time and lower EBL than the conventional MIS tubular decompression. Further, randomized-controlled studies with a larger sample size may be necessary to drive any final conclusions.

P279 - Sarcopenia On Minimally Invasive Spine Surgery: Is Ict Sarcopenia Evaluation A Clinical Outcome Prognostic Tool For Patients Undergoing Mis Trans-Psoas Surgery (XLIF)?

Rodrigo Navarro-Ramirez¹, Juan De Dios Del Castillo-Calcaneo¹, Carolin Melcher¹, Christoph Wipplinger¹, Eliana Kim¹, Maximiliano Gimenez-Gigon¹, Roger Härtl¹

¹Weill Cornell Brain and Spine Center, New York - United States

Introduction: Sarcopenia is defined as the loss of skeletal muscle mass and strength that occurs with advancing age >70yo. It has been significantly associated with self-reported physical disability in both men and women, independent of ethnicity, age, morbidity, obesity, income, and health behaviors. Sarcopenia has proven useful as a prognostic factor in other fields such as oncology and has also been identified to increase Hospitalization and other health care demands. It has been estimated that a 10% reduction in the prevalence of sarcopenia can be valued for $1.1 billion Health Care cost reduction. Sarcopenia has never been considered a prognostic factor for Minimally Invasive Spine Surgery (MISS) procedures. In MISS and spine surgery in general, it is of vital importance to identify patients who are at greater risk for postoperative morbidity and mortality without increasing the costs of preoperative studies. For these reasons, we decided to study the clinical effect of sarcopenia using fan beam intraoperative CT (FBiCT) images from a series of patients undergoing XLIF. Material and Methods: A prospective collection and retrospective analysis of the images obtained intraoperatively using a FBiCT from patients undergoing XLIF between 2014-2017 at our institution were performed. The Psoas-Lumbar Vertebra Index (PLVI) was determined for all patients using the preoperative CT scan obtained inside the operating room using the FBiCT system and following the formula: L4 Psoas para-vertebral index; Psoas Cross Sectional Area (PCSA) = [(right PCSA mm2 + left PCSA mm2 / 2)/ L4 vertebral body surface area (VBSA) mm2. Patient demographics (age, sex, surgery level), Complications, Surgical Time, Estimated Blood Loss, ODI and VAS scores from preoperative and postoperative consultations and Surgery Failure (requiring re-intervention) was obtained from the electronic records of these patients. Linear regression was used to assess the independent effect of sarcopenia among other comorbidities. Results: We collected data of 27 patients; 19 subjects were finally included after 8 were excluded due to insufficient data at the latest follow-up. 10 were males (52%), with a mean age of 70.4 years; PLVI values below the mean (0.92) were classified as Sarcopenic (42%). Of the total of 5 failures, 3 (60%) were in the normal muscle group. Pre-and postoperative clinical outcomes showed non-statistically significant results when compared with each other and as independent factors. Conclusion: Intraoperative imaging technology and sarcopenia assessment was not found of predictive value for poor clinical outcomes after XLIF in elderly population. Larger sample studies are needed to confirm these results.

P280 - Optimal 2d Imaging For Safe Placement Of Percutaneous Pedicle Screws In The Cervical Spine

Jorrit-Jan Verlaan¹, Ronald L.A.W. Bleys², F. Cumhur Öner¹, Martijn Van de Giessen³

¹Department of Orthopedics, Universitair Medisch Centrum Utrecht, Utrecht - Netherlands ²Department of Anatomy, Universitair Medisch Centrum Utrecht, Utrecht - Netherlands ³Dept. Clinical Science & Medical Affairs, Image Guided Therapy, Philips, Best - Netherlands

Introduction: The practice of percutaneous placement of pedicle screws has been shown to decrease soft-tissue damage, reduce blood loss and improve patient recovery. Unfortunately, placement of percutaneous pedicle screws in the cervical spine is not yet routinely practiced due to concerns of potential damage to the vertebral artery or spinal cord in case of misplaced screws. Accurate placement of percutaneous pedicle screws is currently hampered by difficult perioperative visualization of the bony anatomy and by a lack of dedicated tools for percutaneous cervical implants. Using standard anterior-posterior and lateral fluoroscopy views, determining the optimal location and orientation for pedicle screw placement is difficult due to the complex 3D anatomy of the neck. In this study we explored the use of fluoroscopy views perpendicular to the pedicle for safe minimally invasive cervical pedicle screw placement. Material and Methods: Cannulated 3.5 mm diameter AO small-fragment screws (simulating percutaneous cervical pedicle screws) were percutaneously placed in a cadaveric specimen (female, 90 years old). Optimal fluoroscopy views were obtained by acquiring a cone-beam CT volume and planning an optimal virtual screw path through the cervical pedicle into the vertebral body, maximizing screw diameter and length. Based on this path the fluoroscopy C-arm was automatically positioned to have a cervical pedicle ‘bulls-eye’ view. In this view a K-wire was placed into the pedicle under fluoroscopy, followed by introduction and placement of the cannulated screw. Imaging and path planning were performed with a Philips Allura FD20 with XperGuide. Accurate screw placement was validated through cone-beam CT acquisition and anatomical dissection afterwards. Results: Nine pedicle screws were placed at the C1 (one screw) C3, C4, C6 and C7 (two screws each) levels. All screws were positioned with a clinically acceptable accuracy, avoiding both spinal canal and vertebral arteries as could be observed with postprocedural CT images and following anatomical dissection. During placement 40 cone-beam CT acquisitions were used for intermediate and final confirmation of accurate screw placement. 5 K-wire placements were adjusted based on 3D acquisitions: 3 after just entering the cortical bone, 2 after lateral placement. Conclusion: Accurate placement of percutaneous pedicle screws is feasible in the cervical spine using a pedicle ‘bulls-eye view’. In this experiment, cone-beam CT was used more extensively for intermediate validation than is acceptable in clinical practice. With increased experience in using pedicle views, we expect that this can be decreased to acceptable radiation exposure. The fluoroscopy pedicle views thereby form an enabling step towards development of percutaneous cervical pedicle screw placement procedures and tools.

P281 - Minimally Invasive Oblique Lumbar Interbody Fusion In Degenerative Lumbar Spinal Disorders: Assessment Of Early Radiological And Clinical Outcomes

Nisarg Parikh¹, Amit Jhala², Manish Mistry²

¹Spine Fellow, Chirayu Fracture and Orthopeadic Hospital, Ahmedabad - India ²Consultant Spine Surgeon, Chirayu Hospital, Ahmedabad - India

Introduction: Minimally Invasive Lumbar Interbody Fusion is a retroperitoneal approach which uses corridor between psoas and great vessels. Here we have retrospectively analyzed its early radiological & clinical outcomes in degenerative lumbar spine disease. Methods: OLIF was carried out in 49 segments of 38 patients from May 2016 to August 2017. Patients with degenerative lumbar spine disease were included whereas patients with infection, trauma, lumbar disc prolapse, severe bony canal stenosis, lysthesis of grade 3 or more were excluded. 34 patients (45 segments) were included in this study. All patients were operated from left side. 40 segments had posterior percutaneous and 5 segments had anterior fixation. Auto graft was used in 21 patients (31 segments) and artificial bone graft was used in 13 patients (14 segments). Indirect decompression by distraction was achieved in all patients. Neuromonitioring was not used. Clinical assessment was done according to modified Macnab’s criteria. Radiological assessment was done on lateral radiographs of lumbosacral spine & MRI. Percentage improvement in foraminal height, disc height, reduction of lysthesis & increase in segmental lordosis were measured on radiographs and increase in overall area of spinal canal was evaluated on MRI scans. Results: Out of 34 patients 11 were male and 23 were female. Average age was 63 years. Single segment fusion was done in 24, 2 segment fusion in 9 and 3 segment fusion was done in 1 patient. Average follow up was 5 months. By modified Macnab’s criteria, 24 patients (70.59%) had excellent, 8 patients (23.53%) had good & 2 patients (5.88%) had fair outcomes. None required direct decompression. Per operative complications included rupture of iliolumbar vein in 1(2.94%), breach of peritoneum and fracture of superior endplate of inferior vertebrae in 2 (5.88%) patients. All patients had postoperative graft site pain in which autograft was taken. Graft site fracture occurred in 2 (5.88%) patients which got healed within 3 weeks. Ipsilateral psoas weakness/ pain was seen in 11 (32.35%) patients which got resolved within 3 weeks. 1 (2.94%) patient had superficial /deep infection. 6 (17.64%) had contralateral radiculopathy with motor deficit in 1 patient. 3(8.82%) of them required direct decompression. Conservatively managed patients recovered partial to fully within 1 month. 1(2.94%) patient had numbness in area distribution of left genitofemoral nerve. Overall complication rate was 40.12%. On radiological assessment, overall improvement in foraminal height was 20.78%, disc height improved by 97.32%, average lysthesis reduction was 7.1%, increase in segmental lordosis was 3.16^o.36 segments were studied on T2 W MRI axial scans. Overall improvement in spinal canal area was 46.54%. Conclusion: Early clinical outcomes of this study have shown excellent to good results & also significant increase in foraminal height, disc height, segmental lordosis, spinal canal area and reduction of listhesis on radiological assessment with low rate of irreversible complications.

P282 - The Value Of Percutaneous Endoscopic Interlaminar Discectomy In The Treatment Of Lumbar Disc Herniation

Bo Liang¹, Guowang Zhang¹, Jianguang Xu¹, Xiaofeng Lian¹

¹Department of orthopedics, Shanghai Sixth People’s Hospital, Shanghai - China

Objective: To evaluate the usage of percutaneous endoscopic interlaminar discectomy (PEID) in the treatment of lumbar disc herniation. Methods: We retrospectively analyzed the data of 44 patients who were treated surgically with percutaneous endoscopic interlaminar discectomy in our hospital from March 2016 to March 2017. Among these 44 cases, there were 39 males and 5 females, with an average age of 37.8 (18-61). 33 patients received PEID for a single level, and 11 patients received hybrid surgery of PEID+ percutaneous endoscopic transforaminal discectomy (PETD) for two consecutive levels. As to the anesthesia performed on these patients, general anesthesia was used for 7 patients and local infiltration anesthesia was delivered to other 37 patients (surgery was ceased for one patient due to intolerable pain, and changed to general anesthesia). The time cost of surgery on single level was 41-160 min (56.8 on average), and 85-180 min (94.5 on average) for two levels. Blood loss was both low in two types of surgery. Results: Surgeries were performed successfully on all patients, excepted for one patient who cannot tolerate the pain under local infiltration anesthesia, and change to general anesthesia. Among all 44 patients, 42 surgeries were performed on L5/S1 segment, 2 surgeries on L4/5 segment. 5 patients received PEID because of the failure of puncture from transforaminal approach. Upward migrated herniated discs were found in 4 patients. Calcified herniating discs were shown in 6 patients. 32 surgeries were done through shoulder approach of nerve root, and among them, discography was performed on 28 patients. 12 surgeries were delivered through axillary approach. The mean time to return to off-bed activity was 6.8 days (1-15). The mean VAS scores for back and leg pain decreased to 1.3 postoperatively from 4.8 preoperatively, ODI were significantly improved from 56.7 preoperatively to 22.4 postoperatively. Complications such as nerve injury, infection and recurrent disc herniation in one year post-op were not seen in all patients. Conclusion: PEID is a beneficial supplementary for PETD, especially in the circumstances that having trouble with puncture in thansforaminal approach, upward migrated disc herniation as well as calcified disc herniation. For PEID, local infiltration anesthesia was suitable, it can facilitate the implementation of discography, and it is also convenient for the surgery to change the approach from transforaminal to interlaminar temporarily.

P283 - Metrics Development For A Minimally- Invasive Lumbar Decompression Procedure For Surgical Training

Carolin Melcher¹, Rodrigo Navarro², Christoph Wipplinger², Michael Cunningham³, Kevin Foley⁴, Andreas Korge⁵, Wegener Bernd¹, Christof Birkenmaier¹, Roger Hartl¹

¹Department of Orthopedic Surgery, Physical Medicine and Rehabilitation, UNiversity Hospital LMU Munich, Munich - Germany ²Weill Cornell Brain and Spine Center, New York - United States ³AO Foundation, AO Education Institute, Duebendorf - Switzerland ⁴Semmes-Murphey Clinic and Professor, Departments of Neurosurgery, Orthopaedic Surgery, and Biomedical Engineering, University of Tennessee Health Science Center, Memphis - United States ⁵Schön Klinik München Harlaching, Department of Spine Surgery, Munich - Germany

Introduction: Assessment of medical education and competence is always difficult and becomes even more challenging within postgraduate training. Surgical trainees should acquire certain competencies during training, however assessment and measurement of these competencies have been difficult. To characterize the essential operational definitions (metrics) of a reference step-by-step minimally-invasive lumbar decompression procedure for use in surgical training and to evaluate the appropriateness of the steps and errors identified. Methods: A metrics group of three experienced spine surgeons and an educationalist deconstructed a lumbar decompression procedure by defining essential steps and errors. After individual identification, the metrics were discussed and defined by consensus. Twelve videos of the procedure were analyzed to assess the defined essential steps and potential errors. During this process, the metrics were tested for clarity and the ability to be scored in binary fashion as either occurring or not occurring. The metrics were subjected to analysis by 5 more spine surgeons with different levels of experience to obtain face and content validity using a modified Cooke methodology With all steps and errors defined, the surgeons in the metrics group performed 2 procedures on a lumbar stenosis simulation model to translate the theoretical step-by-step module into an operational procedure for future surgical training. Results: Main phases, steps and errors were identified in the characterization of a lumbar decompression procedure. Procedural errors were specified, with some designated as sentinel errors. Amendments to the metrics were made after performing a modified Cooke deliberation. Consensus on the resulting metrics was obtained and face and content validity was verified. Conclusions: This study confirms that a group of experienced spine surgeons with educationalist support is able to perform task deconstruction of a lumbar decompression procedure creating a step-by-step module that accurately characterizes the essential components, which can be revised and validated by a panel of spine surgeons. The resulting metrics can be used to improve surgical skills training and assess trainee progression toward proficiency. A second phase to compare training progress in residents using a simulation model is planned.

P284 - Facet Sparing Contralateral Approach For The Treatment Of Foraminal Stenosis Combined With Degenerative Lumbar Scoliosis

Se Young Pyo¹, Kee Chang Lee¹, Yong Tae Jung¹

¹Department of Neurosurgery, Busan Paik Hospital, Inje University, Busan - Korea, Republic

Introduction: Lumbar foraminal stenosis had been treated if it were indicated surgery by facetectomy with fusion surgery or foraminal decompression through contralateral approach. But if these pathologies have combined with lumbar degenerative scoliosis(DLS), surgical treatments methods had been variable from decompression only to long level fusion. Then we introduced tailor retractor or tubular retractor guided facet sparing foraminotomy through a contralateral approach to the treatment of these pathologies. The aim of this study is to evaluation of clinical result along approach side such as concave or convex, and radiologic changes of Cobb angle of DLS after this surgical approach to foraminal stenosis combined with DLS. Material and Methods: From 2011 to 2016, 22 patients were enrolled. The patients had symptoms of bilateral or unilaterally dominant lower extremity radiculopathies with/without neurological intermittent claudication, who was defined multilevel pathologies such as foraminal stenosis (FS) with/without foraminal disc herniations combined with DLS which had additional central spinal stenosis, lateral recess stenosis, or pre-operative minimal instability such as vacuum disc on image studies. 10 patients had foraminal stenosis on convex side and others had concave side. All the patients underwent foraminotomy with/without discectomy via a contralateral approach through tailor retractors or tubular retractors. Pre- and post-operative back and leg pain were evaluated by Visual Analogue Scale (VAS). Functional outcomes were evaluated using MacNab’s criteria. Lumbar coronal balance was measured by Cobb angle. Results: Back and leg pain relief was assessed by Visual analogue scale (VAS) postoperative immediately and 2,4,6 months after procedure. Early post-operatively there was significant improvement in VAS back pain and VAS leg pain (p < 0.001) on the pathology and the approach side. After one year there was also significant improvement in VAS back pain and VAS leg pain (p = 0.001) on the pathology and the approach side. The functional outcome was excellent and good in almost. Although surgical fields of concave side approaches were more narrow than convex side, that results were not differ between them. Mean coronal Cobb angle improvement was 6.3 ± 0.05 (p < 0.05). Conclusion: Facet sparing contralateral foraminotomy with/without contralateral discectomy was an effective technique with favorable clinical outcome for treatment of foraminal stenosis combined with degenerative lumbar scoliosis even in concave side. And this procedure would be expected with reducing fusion surgery under these diseases entity. Randomized comparison study with fusion surgery and evaluation of long term stability would be needed.

P285 - Minimally Invasive Treatment Of Hangman Fractures

Francisco Ardura¹, Ruben Hernandez-Ramajo², Jesus Crespo², Raul Corredera³, David Noriega¹

¹Department of Orthopedics, Clinical Hospital. Department of Surgery, School of Medicine, Valladolid - Spain ²Department of Orthopedics, Clinical Hospital, Valladolid - Spain ³Department of Radiology, Clinical Hospital, Valladolid - Spain

Introduction: Hangman fractures are defined by the injury of the C2 Neural arch produced by multiple mechanisms acting on the cervical spine. Its diagnosis is based on the image tests as the simple radiology or TAC that can be used for a good definition of the bone injury and the RMN what indicates if there are disc and ligaments lesions. The treatment is still controversial depending on the type of lesion presented by the patient and its stability, so it may vary from a conservative treatment to surgery with C1-C3 fusion. This surgery has a high risk of damage vascular and nerve structures so during the last years a synthesis of the C2 fracture has begun to be used through the use of transpedicular screws what get a good stabilization of the fracture. Moreover we must also take into account the variability of the cervical spine between patients because the use of navigated surgery with O-arm system decreases the inherent risks in screw insertion. Material and Methods: We present three patients with C2 traumatic spondylolisthesis treated surgically. These patients were operated in prone position with posterior approach in cervical spine, osteoshyntesis of the fracture using the surgery navigated with O-arm which enables to control the insertion point with maximum mechanical efficiency, choose the trajectory of the implantable device, calculation of the length of the implanted the correct insertion of the screw having under control all vessels and nerves. Results: The evolution of patients from the point of view of the surgical and fracture healing was excellent without neurological or surgical complications. Balance of the cervical spine at the time medical discharge was under normal values.

Conclusion

1. Hangman’s fracture osteosynthesis:

2. avoids side effects of decreased mobility because of the fusion or the disadvantages of prolonged immobilization

3. shorten period of recovery

The technical application of high-resolution navigation:

increases the chances of success

reduces potential iatrogenic injury and surgical exposure

P286 - Effect Of Minimally Invasive Oblique Lumbar Interbody Fusion On Indirect Neural Decompression

Nisarg Parikh¹, Amit jhala², Manish Mistry²

¹Spine Fellow, Chirayu Fracture and Orthopeadic Hospital, Ahmedabad - India ²Consultant Spine Surgeon, Chirayu Hospital, Ahmedabad - India

Introduction: Direct decompression and interbody fusion is one of the most sought after technique for degenerative unstable lumbar spine disease. However Minimally invasive Oblique Lumbar Interbody Fusion can be used for such disorders which alleviates the need and thereby complications of direct decompression. Here we have analyzed efficacy of minimal access OLIF to achieve indirect decompression after assessing radiological and clinical outcomes. Methods: This is retrospective study. Oblique lumbar interbody fusion was carried out in 49 segments of 38 patients over the period of 16 months from May 2016 to August 2017 with the longest follow-up for 1 year. Patients with degenerative lumbar spine disorders were included whereas patients with infection, trauma, lumbar disc prolapse, severe bony canal stenosis, lysthesis of grade 3 or more were excluded. So 45 segments of 34 patients were included in this study. All patients were operated from left side by minimally invasive oblique lumbar inter body fusion with cage. 40 segments had posterior percutaneous fixation and 5 segments had anterior fixation. Auto graft was used in 21 patients (31 segments) and artificial bone graft (hydroxyapatite crystals and calcium tri-phosphate) was used in 13 patients (14 segments) along with cage. Indirect decompression by distraction was achieved in all patients. None of the patients had direct decompression done. No neuromonitioring was carried out on the patients. Per operative and perioperative complications were noted. Patients were followed up at 6 weeks, 3 months, 6 months and 1 year. All patients were clinically and radiologically evaluated. Clinical assessment was done according to modified macnab’s criteria. Radiological assessment was done on standardized pre and postoperative lateral radiographs of lumbosacral spine. Post operative MRI was done in 28 patients (36 segments). Percentage improvement in foraminal height, disc height, reduction of lysthesis & increase in segmental lordosis were measured on radiographs and increase in overall area of spinal canal was evaluated on MRI scans depending on the Schizas grading of the stenosis. Results: Out of 34 patients 11 were male and 23 were female. Age was from 40 to 82 years with average age of 63 years. Diagnosis was Disc degeneration in 3 patients, degenerative lysthesis in 20 patients, lytic lysthesis in 2 patients, Lumbar stenosis in 4 patients and adjacent segment degeneration in 5 patients. Single segment fusion was done in 24 patients, 2 segment fusion was done in 9 patients and 3 segment fusion was done in 1 patient. Average follow up was 5 months. By modified MacNab’s criteria out of 34 patients, 24 patients (70.59%) had excellent, 8 patients (23.53%) had good & 2 patients (5.88%) had fair outcomes. All were benefited with indirect decompression. None required direct decompression post operatively due to persistent preoperative symptoms. 3(8.82%) patients required direct decompression due to contralateral radiculopathy. On radiological assessment, overall improvement in foraminal height was 20.78% and disc height improved by 97.32% as compared to preoperative status. Lysthesis was present in 39 segments out of which 36 segments had grade 1 and 3 had grade 2 lysthesis. Average lysthesis reduction was 7.1% in affected individuals. Overall increase in segmental lordosis was 3.16 degrees.36 segments were studied on T2 W MRI axial scans. Overall improvement in spinal canal area was 46.54%. Conclusion: Minimally invasive OLIF approach can achieve indirect decompression with excellent to good clinical results & significant radiological improvement in the form of increase in foraminal area, disc height, segmental lordosis, spinal canal area & reduction in lysthesis. Thus it alleviates all the complication associated with direct decompression.

P287 - Women Do Not Have Poorer Outcomes After Minimally Invasive Lumbar Fusion Surgery - A Five-Year Follow-Up Study

Ming Han Lincoln Liow¹, Graham Seow-Hng Goh¹, William Yeo¹, Zhixing Marcus Ling¹, Wai-Mun Yue¹, Chang Ming Guo¹, Seang Beng Tan¹

¹Department of Orthopaedic Surgery, Singapore General Hospital, Singapore - Singapore

Introduction: Females have been shown to report more pain than men, with studies demonstrating the female gender to be an independent risk factor for poorer functional outcome after lumbar fusion surgery. It is unclear why women perform worse after lumbar fusion surgery. It is postulated that their poorer outcomes are potentially related to a higher incidence of chronic low back pain and psychological factors. Recent studies have shown that women may not fare worse than men. However, these studies reported on heterogeneous cohorts of patients who underwent a myriad of different lumbar spine surgical procedures and short-term follow-up data. To our knowledge, there are no studies reporting the effect of gender on the outcomes of minimally invasive (MIS) transforaminal lumbar interbody fusion (TLIF). The aim of our study is to determine if gender influences functional, patient-reported (PROM), health-related quality-of-life (HRQoL), satisfaction and fulfilment of expectations outcomes after MIS-TLIF at five-year midterm follow-up. Material and Methods: Prospectively collected registry data of 907 patients who underwent MIS-TLIF at a single institution from 2004-2013 were reviewed. Of these, 296 patients (94 males and 202 females) were reviewed at five-year follow-up. All patients were assessed pre- and post-operatively at two and five years, with numerical pain rating scale (NPRS back and leg pain), Oswestry Disability Index (ODI), Short-form 36 Physical and Mental component scores (SF-36 PCS and MCS), North American Spine Society (NASS) score for neurogenic symptoms (NS), return to work (RTW), return to function (RTF) and satisfaction/expectation fulfilment. Length of operation, length of stay and comorbidities were also recorded. Student’s T-test and Chi-Square test was used to compare parametric and proportion-based outcomes respectively between genders. Multiple logistic regression was performed with gender as the dependent variable to identify associated independent variables. Results: Females who underwent MIS-TLIF were generally younger (p = 0.04) and had significantly higher prevalence of osteoarthritis (p = 0.04). In addition, females had significantly poorer preoperative ODI (p < 0.001) and SF-36 PCS/MCS scores (p < 0.01). There were no significant differences in BMI, length of procedure, length of stay or proportions of other comorbidities. However, at two-year and five-year follow-up, there were no significant differences in functional, PROM or HRQoL scores between genders. In addition, both groups reported similar proportions that RTW and RTF. At 5 years, 89.4% of males and 88.6% of females were satisfied with their surgeries (p = 0.99), while 92.6% of males and 94.1% of females had their expectations fulfilled (p = 0.81). Conclusion: Women who elect to undergo MIS-TLIF have poorer function and QoL than men. However, women demonstrated greater improvement after surgery, attaining similar clinical outcomes, PROM and HRQoL scores at 5 years midterm follow-up. In addition, women returned to work at a comparable rate to males after MIS-TLIF, reporting equivalent rates of satisfaction and expectation fulfilment with surgery. Our study demonstrates that poorer preoperative function in females should not be considered as an absolute contraindication for MIS-TLIF surgery and the management of degenerative spine disease should not be biased by gender, since both sexes are capable of experiencing comparable outcomes with surgery.

P288 - Minimally Invasive Transforaminal Lumbar Interbody Fusion Improves Mental Health In Patients With Lower Preoperative Mental Health

Ming Han Lincoln Liow¹, Graham Seow-Hng Goh¹, William Yeo¹, Zhixing Marcus Ling¹, Wai-Mun Yue¹, Chang Ming Guo¹, Seang Beng Tan¹

¹Department of Orthopaedic Surgery, Singapore General Hospital, Singapore - Singapore

Introduction: A subgroup of patients who undergo minimally invasive (MIS) transforaminal interbody fusion (TLIF) have poorer outcomes and remain dissatisfied. Poor preoperative mental health has been shown to predict outcomes following lumbar spine surgery. However, the effect of MIS-TLIF on mental health is unclear. Poor preoperative mental health may be caused by bodily pain and functional limitations associated with degenerative lumbar spine conditions, which have the potential to improve postoperatively. The aim of our study is to: (1) determine the impact of MIS-TLIF on mental health and, (2) examine the influence of mental health on functional, patient-reported (PROM), health-related quality-of-life (HRQoL), satisfaction and fulfilment of expectations after MIS-TLIF. Material and Methods: Prospectively collected registry data of 907 patients who underwent MIS-TLIF at a single institution from 2004-2013 were reviewed. Of these, 296 patients with preoperative and complete 2 year and 5 year postoperative follow-up data were included in the study. Linear regression was used to determine improvement in mental health at 2 years and 5 years after MIS-TLIF according to preoperative SF-36 Mental Component Summary (MCS) scores. Patients were subsequently stratified into Low MCS (<50, n = 183) and High MCS (≥50, n = 113) based on their preoperative MCS scores and assessed pre- and postoperatively at 2 and 5 years. Student’s T-test and Chi-Square test was used to compare parametric and proportion-based outcomes respectively between groups. One-way ANOVA was used to compare preoperative, 2 and 5 year MCS scores in both groups. Results: Low MCS group demonstrated poorer clinical outcomes, PROM, HRQoL and longer hospital stay. Lower preoperative MCS score was predictive of greater improvement in MCS at 2 years (Coefficient = -0.58, R = 0.58, p < 0.001) and 5 years (Fig. 1, coefficient = -0.55, R = 0.61, p < 0.001) postoperatively. In general, the High MCS group performed better than the Low MCS group (Table 2). At 2 years, High MCS group had significantly lower ODI (p < 0.01), NASS NS (p < 0.01), NPRS (back and leg pain)(p = 0.03). At 5 years, High MCS group had significantly lower ODI (p = 0.02), NASS NS (p < 0.01) and NPRS (leg pain)(p < 0.01). Both groups reported similar proportions that RTW, however, the High MCS group had a larger proportion of patients that RTF at 2 years (73.5% vs 59.6%, p = 0.02) and 5 years (84.1% vs 72.7%, p = 0.03) (Table 3). There were no significant differences in satisfaction/expectation fulfilment between the High and Low MCS groups, however, a trend towards higher satisfaction/expectation fulfilment was noted in the High MCS group (Table 4). Conclusion: The relationship between mental health and postoperative outcomes after MIS-TLIF is complex, as the organic functional limitations of degenerative spinal conditions are likely to contribute to poorer mental health. Our study has demonstrated that MIS-TLIF has the potential to provide greater improvements in postoperative mental health in patients with lower preoperative mental health. However, at 5 years, patients with lower preoperative mental health scores still performed poorer, despite demonstrating greater improvements. MIS-TLIF may, in part, lead to improvements in mental health, however, preoperative optimisation of mental health must still be pursued to ensure ideal outcomes.

P289 - Clinical And Radiological Outcome Of Modified Mini Open And Open Transforaminal Lumbar Interbody Fusion – A Comparative Study

Sudhir Ganesan¹, Vignesh Jayabalan¹, Karthik Kailash¹

¹Department of Spine Surgery, Chennai – India

Introduction: Studies have shown that minimally invasive transforaminal lumbar interbody fusion (MTLIF) is associated with less blood loss, shorter hospital stay and less pain. We modified the MTLIF technique by direct free hand insertion of pedicle screws using stab incisions without tubular retractors and compared the clinical and radiological outcome of modified mini open TLIF (modMOTLIF) versus open TLIF(OTLIF). Material and Methods: The study included 24 patients in modMOTLIF and 27 patients in OTLIF group. Average period of follow up was 25.6 months. Clinical outcome was measured using VAS and ODI. Serial X rays were done at 1, 3, 6 and 12 and 24 months to assess union and presence of instability. We also compared the blood loss and length of hospital stay in both the groups. Results: All patients had a progressive improvement in VAS and ODI. There was no difference in preop and postop ODI, VAS leg between the groups.The immediate postop VAS back was significantly high in OTLIF compared to modMOTLIF group whereas there was no difference at 1 and 2 yrs. Radiological analysis showed nonunion in 2 mMOTLIF and 1 OTLIF patient. Average blood loss was 63 ml in modMOTLIF group and 254 ml in OTLIF group. Mean hospital stay was 3 days for modMOTLIF and 5 days for OTLIF patients. Conclusion: modMOTLIF is associated with reduced blood loss, shorter hospital stay compared with OTLIF. There is no significant difference in the clinical and radiological outcome between both the groups at the end of two years despite reduced back pain in the immediate postoperative period in modMOTLIF patients.

P290 - Are Lumbar Lamellar 3d Titanium Cages More Or Less Prone To Subsidence?

Alessandro Versace¹, Marco Sassi², Roberto Assietti³

¹Department of Neurosurgery, ASST Fatebenefratelli Sacco, Milano - Italy ²Neurosurgeon in IRCCS Istituto Ortopedico Galeazzi, Milan - Italy ³Chief of the Department of Neurosurgery, ASST Fatebenefratelli Sacco, Milan - Italy

Introduction: Minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) is one of the most popular surgical procedure because of the reduced neural tissue traction compared with other posterior lumbar interbody fusion and reduce trauma to back muscles and bony structures compared with conventional open procedures. Subsidence is of particular concern after this technique because these rely on indirect decompression of the neural elements. There are several studies that correlate different shapes of cages and some materials with the risk of subsidence. We have been using lamellar 3D titanium cages (cascadia) for three years, and we reviewed our data from 2015 to 2017 to see if this material has real benefits for subsidence. Materials and Methods: A retrospective study included 40 patients underwent MIS-TLIF L4-L5 or L5-S1 (23 and 17 respectively) with K2 M Cascadia cages and bilateral penduncolar screws between 2015 and 2017 (monocenter and monosurgeon cases); Mean age 59 years; 25 M and 15 F. CT scan was performed the day after surgery, to esclude early cage subsidence (ECS) due to intraoperative vertebral endplate violation) and at 6 months to evaluate delayed cage subsidence (DCS). DCS was measured and classified in according with Marchi et al. based on the amount of cages subsidence into the vertebral endplates: grade 0 0-24%, grade I 25-49%, grade II 50-74%, grade III 75-100%. Results: 2 patients had ECS at the first CT so they were excluded from the study. The others 38 were studied at 6 months: just 3 developed DCS (7.9%), 2 grade 0 (5.3%) and 1 grade I (2.6%). Grade 0 and grade I were considered by Marchi low-grade subsidence indeed no patients developed clinical subsidence. Conclusions: In our case the subsidence rate is 7.8%, slightly lower than that of the literature (higher of 10%). Furthermore, we have just low-grade subsidence without clinical symptoms. We think that the lamellar 3d titanium technology of K2 M Cascadia cages plays an important role to achieving these results. Follow-up is short but in a recent study Malham et al. and others older studies found that noted subsidence occurring in the early postoperative period between 6 weeks and 3 months. We will continue follow-up and we need a comparative study between different kinds of material to confirm these data.

P291 - Extraforaminal Technique For Cage Insertion And Pedicle Screw Placement

Asdrubal Falavigna¹, Orlando Righesso², Frederico De Farias³, João Pedro Britz³

¹University of Caxias do Sul - Brazil ²Hospital Tacchini, Bento Gonçalves - Brazil ³University of Caxias do Sul - Brazil

Introduction: Approaches to inserting a MIS cage can be challenging due to the unique anatomy. The transfacet approach requires removing the articular facet complex before inserting the cage into the disc space. The extraforaminal approach can spare the articular facets unless spinal canal decompression is necessary and relying only in the anatomical features. This study aimed to describe the MIS extraforaminal transmuscular microsurgical approach to promote cage insertion and nerve decompression. Material and Methods: A series of 72 patients underwent a minimally invasive transmuscular microsurgical approach for the treatment of degenerative disc disease. All patients were clinically evaluated using the visual analog scale (VAS), Oswestry Disability Índex (ODI), satisfaction index (SI), and hospital anxiety and depression scale (HAD) preoperatively and postoperatively at 6 months and yearly.

Results: Both pain scores and functional status showed significant improvement after surgery (p < 0.001): radicular pain decreased from a VAS score of 7.9 to one of 1.3, lower back pain from VAS score of 2.4 to 1.4, and the Oswestry Disability Index from 42.0 to 12.3. The satisfaction index is over 87%. The surgeons’ confidence was high without a steep learning curve. Spinal decompression could safely be performed by medially advancing the tube or retractor, having the yellow ligament as an anatomical barrier before visualizing the nerve root. Conclusion: The transmuscular extraforaminal microsurgical approach combines the advantages of using the conventional anatomy that is always available independent of the disease and readily reaching the intervertebral disc space.

P292 - Dual-Docking In Minimally Invasive Tubular Approach For The Treatment Of Lumbar Spine Disorders: A Technical Note

Ankit Patel¹, Arvind Kulkarni¹, Mehul Sarkar¹, Navin Mewara¹, Sameer Ruparel¹

¹Department of Orthopaedics & Spine Surgery, Bombay Hospital, Mumbai – India

Introduction: Minimally invasive surgery has expanded over the past two decades initially used only for treatment of lumbar disc herniation but now is used to perform spinal fusion, extended spinal decompression as well as intra-dural tumor excision. Lately it has gained criticism for the cautery induced soft tissue trauma and in order to reduce such trauma we ventured to use a technical variation. In this note, we aim to discuss the use of Dual-Docking in minimal surgical approach for the treatment of Lumbar spinal disorders with the METRx system. Material and Methods: A Tubular retractor when placed over the last dilator has a thin, albeit conspicuous layer of muscle overlying the bony structure underneath. It is a common tendency to cauterize it so as to proceed further. We devised and implemented a Dual-Docking approach in which, after the first docking the herniated muscle (creep) is longitudinally split and sub-periosteally erased off the underlying lamina with the initial dilator and sequentially increasing sizes of dilators are placed over this re-docked initial dilator. The second docking of METRx tube is a true minimal invasive muscle sparing docking helping to prevent native tissue damage and attain a secure, stable docking for further surgical steps. Results: We implemented this strategy of Dual-Docking for all our Tubular surgeries preserving more muscle tissue. This approach also helps in reducing blood loss, improving vision at the periphery, secure docking, wanding of tube to reach distant areas for decompression, improved muscle fall-back post tube removal and faster recovery. Conclusion: A Dual-Docking minimal surgical approach using a tubular retractor makes the procedure a true muscle sparing technique. This extra step is useful tool to decrease the surgical footprint, expedite the overall surgical process, minimize postoperative local site pain and preserve muscle function.

P293 - Clinical Experiences Of Percutaneous Biportal Endoscopic Spine Surgery

JinHwa Eum¹, Seung Deok Sun¹

¹Department of Neeurosurgery, Sun Orthopedic Clinic, Seoul - Korea, Republic

Introduction: Traditionally, lumbar spine diseases that require surgical intervention are treated with an open decompressive procedures. Microsurgery is a very effective technique. PELD (Percutaneous Endoscopic Lumbar Discectomy) was introduced and some experienced surgeons had good results. But it may have limited vision and complete decompression may not be successful in some cases. Biportal endoscopic surgery is different from other spinal endoscopic system with one portal. There are two skin portals, one portal for endoscope and the other for working instruments. Thus the endoscopic system is similar to joint arthroscopy. Percutaneous biportal endoscopic operating procedure is the same pattern as open spine surgeries under excellent visualization. The authors present cases of lumbar discectomy, central and foraminal decompression, lumbar interbody fusion, and posterior cervical foraminotomy and discectomy using percutaneous biportal endoscope. Materials and Methods: We collected data retrospectively from February 2011 to February 2016. Results: A total 534 patients (357 female, 177 male) were operated. 84.5% patients improved clinically and radiographically after percutaneous biportal endoscopic surgery. Conclusions: Percutaneous biportal endoscopic spinal decompression would be a safe and effective minimally invasive procedure compared to conventional open surgery. Duration 2011 Feb. - 2016 Feb. Total 534. hld 157 - hcd 57 - htd 5 - spondy 78 - ls 237. Results: 84.5% excellent or good, 9.7 fair, 5.8 poor.

P294 - Usefulness And Results Of Minimum Invasive Cervical Laminoplasty With Titanium Plate

Takaki Yoshimizu¹, Kanji Sasaki¹

¹Spine Center, Seirei Hamamatsu General Hospital, Hamamatsu - Japan

Introduction: Cervical laminoplasty is a procedure to enlarge the spinal canal. It is taken priority that widening of whole canal, so minimizing the invasion is difficult. Thus we often troubled with severe nape pain after surgery, caused by muscle or bone invasion. We deviced Minimum invasive Laminoplasty (MIS-LP) from 2014. Using our procedure, skin incision is about 1 inch, and plate and screw for lamina fixation deliver primary strong fixation. This study aimed to analyze the usefulness and result of this procedure. Material and Methods: An observational retrospective study was performed, reviewing the clinical records from preop to postop of patients performed cervical laminoplasty.144 cases with LP (107 male/ 37 female; average 64.9 years old) were investigated. All cases were followed more than 12 months. 107 cases were undergone MIS-LP. This procedure is combination of Shiraishi�fs and Hirabayashi fs method. Splitting spinous process preserve muscles damage are preserved with spinous process. After reveal the lamina without spinous process, we undergo both open-door laminoplasty from C4 to C6 and dome laminoplasty to C3 and C7. For comparative cases, 37 cases were undergone conventional LP (open-door or French-door laminoplasty: hydroxyapatite blocks, more than 3 inch). Japanese Orthopaedic Association Score (JOA Score) and Hirabayashi fs Recovery Rate at one year after operation, Operative time, amount of bleeding, complications and survival time were investigated. Postoperative pain was evaluated by Numerical rating scale (NRS). We also checked postoperative change from preoperation cervical lordosis and spondylolisthesis. For comparison between two groups, The Wilcoxon test was used for statistical analysis. Results: There were no cases of worsened neurological deficit and the neurological scores (JOA) were not significantly different in JOA Score. Recovery Rate among two procedures were also same. Surgical time of MIS-LP (average 72 minutes) was significantly superior to conventional procedure (104 minutes). The mean amount of bleeding during MIS procedure (average 39 g) was significantly less than conventional LP (104 g). Nape pain of the minimum-open was significantly less than conventional procedure. Postoperative XP change of cervical lordosis is not significant. Each procedure only showed the slight kyphotic changes (MIS: 3 degree, conventional: 5 degree). Conclusion: Our minimum invasive laminoplasty is safe as old methods. This procedure can reduce surgical time, bleeding nape pain. Surgical outcome is stable. Our device is one of the best options for minimum invasive cervical surgery and this procedure is necessary for coming ages.

P295 - Comparative Analysis Of Radiological And Clinical Outcomes In Extreme Lumbar Interbody Fusion (Xlif): Instrumented Versus Stand-Alone Cages

Reuben CC Soh¹, Nicole XL Toh¹, William Yeo¹, Chang Ming Guo¹

¹Department of Orthopaedic Surgery, Singapore General Hospital, Singapore - Singapore

Introduction: The increased global awareness of restoration of sagittal parameters via the use of multilevel interbody cages has led to minimally invasive XLIF surgery (MIS-XLIF) gaining popularity as an effective minimally invasive option to treat lumbar degenerative diseases. To date, a comprehensive result of instrumented versus stand-alone (SA) cages in MIS-XLIF has not been reported in literature. This study aims to analyse and report on the clinical and radiological midterm outcomes of the two procedures in a head to head comparison. Materials and Methods: We performed a retrospective review of prospectively collected data of patients undergoing MIS-XLIF for lumbar degenerative disease from January 2007 to August 2015. A total of 23 cases of instrumented MIS-XLIF were paired by age, gender, preoperative lumbar lordosis (LL), and number of spinal levels operated to 23 cases of MIS-XLIF with stand-alone (SA) cages. Clinical outcomes were measured using patient-reported outcome measures recorded by independent assessors before surgery, at 1 month, 3 month, 6 month and 2 years postoperatively. Outcomes evaluated include Numerical Pain Rating Score for back (NPRSBP) and leg pain (NPRSLP), Oswestry disability index (ODI) and short form-36 (SF-36). Radiological parameters that were analysed were lumbar lordosis (LL) before surgery, at 1 month, 6 months and 2 years post-surgery. In addition, time to radiological fusion using the Bridwell criteria and cage subsidence were also measured on radiographic plain films. Results: As early as the first month post-surgery, clinical outcome analysis showed both groups improving significantly in the areas of back pain and leg pain and ODI with an increase in SF-36. The mean NPRSBP score showed a reduction of 6.9 to 2.4 (p < 0.05) and the NPRSLP score showed a reduction of 5.4 to 1.4 (p < 0.05). Comparing the SA to instrumented group, we found that both had similar results in terms of ODI (p = 0.429), NPRSBP (p = 0.895), and NPRSLP (p = 0.657). At 24 month follow up, both groups reached similar scores in ODI as well as SF-36 as well as maintenance of back and leg pain (p = 0.989). Radiological analysis of LL showed increment in both groups post-surgery, with greater absolute increase of lumbar lordosis seen in the SA cage group. There was however no statistical difference between the lordosis achieved in both groups. Similar rates of cage subsidence was reported in both groups with during this period. All 46 patients achieved a Bridwell fusion criteria of 2 or more. Conclusions: Stand-alone cages and instrumented XLIF both demonstrate good clinical and radiologic outcomes and provide viable and safe options for lumbar fusion, with no significant clinical advantages over the other. While there may be concern regarding the stability and maintenance of correction of lordosis in SA XLIF, our data demonstrates that both clinical and radiologic parameters are maintained even after a minimum of 24 months of follow up. Comparing both groups, there was no statistical difference in outcomes. Thus, stand-alone XLIF surgery remains an effective option for lumbar fusion in patients who are unable to undergo posterior surgery for instrumentation.

P296 - Translaminar Approach Fenestration Technique For Herniated Nucleus Pulposus In The “Hidden Zone” Of The Lumbar Spine

Jin-Sung Kim¹, Quillo-Olvera Javier¹, Hyun- Jin Jo¹, Guang-Xun Lin¹

¹Department of Neurosurgery, Seoul St. Mary’s Hospital, College of Medicine, The Catholic University of Korea, Seoul - Korea, Republic

Introduction: Most soft lumbar disc herniation can be removed through traditional approaches, but the challenging case is a herniated nucleus pulposus that has migrated into the “hidden zone”. We present our experience with the translaminar approach for this pathology. Material and Methods: Six patients with soft up-migrated lumbar disc herniation underwent surgical treatment via a translaminar approach between May 2014 and June 2017, including percutaneous endoscopic lumbar discectomy (PELD) 3 cases, microsurgery 3 cases. After paramedian approach a small ovoid fenestration was performed using the drill and the herniated disc was removed in a standard manner. Clinical outcomes were assessed regarding preoperative and postoperative numerical rating scale (NRS) scores. Postoperatively, magnetic resonance imaging (MRI), computed tomography (CT), X-ray was taken. Follow-up was routinely carried out 4 weeks postoperatively. Results: Four of the six affected discs were at the L4-5 level, one at L2-3, and one at L5-S1. In all cases, the up-migrated disc herniation was successfully removed through translaminar approach, as confirmed by postoperative MRI. Leg pain disappeared immediately after surgery. The average surgical time was 83.33 ± 20.66 minutes. The average blood loss was 46.67 ± 29.44 ml. Clinical outcomes were acceptable: the average pre-operative NRS was 6.17 ± 0.75 (range, 5-7), which decreased to 2.00 ± 0.63 (range, 1-3) at 4 weeks postoperatively. No complications were observed during the follow-up period. Conclusions: The translaminar approach seems to be an effective and safe to access the “hidden zone” disc herniation, and could be a good alternative technique.

P297 - A Decade Of Xlif: A Single Surgeon’s Experience

Jeffrey Coe¹

¹Silicon Valley Spine Institute, Campbell - United States

Introduction: XLIF has been a major addition in armamentarium of spine surgeons over the last decade. Individual and collective experience over the past decade have made XLIF the procedure of choice for MIS interbody fusion in the TL spine at levels above L5-S1 for many surgeons XLIF, however, is not without its detractors. Many critics, for example, challenge the safety of the MIS lateral approach at L4-5. The purpose of this study is to review a single surgeon’s experience with the XLIF procedure over the last 10+ years with an analysis of the immediate post-operative complications in the entire cohort, along with the radiographic and patient reported outcomes (PRO) for those patients who were followed for greater than 12 months. Material and Methods: A retrospective review of all XLIF cases performed by the author since his adoption of the procedure in mid-2005 was performed. The entire cohort was evaluated with regards to catastrophic complications and the cohort whose surgery was performed before April of 2016 were reviewed for fusion with dynamic radiographs and for clinical PRO on the basis of VAS and ODI. Results: 331 XLIF procedures (578 levels) were performed by the author between August 2005 and April 2017. In this cohort, there were 2 deaths (0.6%) within 6 months of the surgery (cardiac arrest and bowel perforation secondary to obstruction). Femoral nerve palsy occurred in 6 patients (1.8%), none occurred within the last 5 years of the study period. 252 of 306 eligible patients (82.4%) were followed for greater than 12 months (mean 37.5 months, range 12-132 months). Primary diagnoses were degenerative spondylolisthesis in 40.1%, stenosis in 19.4% and degenerative scoliosis in 12.3%. Transient thigh pain/numbness noted in 63 of 253 patients (25.0%). Mean improvement in VAS was 3.5 (p < 0.01) and mean improvement in ODI was 15.7 (p < 0.01). No vascular complications nor implant migration requiring revision was observed. Only one patient was noted to have a non-union at latest follow-up (fusion rate 99.6%). Conclusion: XLIF is a safe and reproducible procedure in selected patients with a safety and outcome profile that is similar or better than that reported in the literature in other lumbar fusion procedures. Femoral nerve palsy in particular appears to have a decreasing incidence with surgeon experience and overall refinements in surgical technique.

P298 - Impact Of Intrathecal Baclofen Therapy Outcomes: In Spasticity, Pain, Anxiety And Satisfaction With Life

Stanislaw Adamski¹, Wojciech Kloc², Krzysztof Basinski³, Agata Zdun-Ryzewska³, Witold Libionka⁴, Patryk Kurlandt¹, Jakub Wisniewski¹, Maciej Racinowski¹, Piotr Murawski¹

¹Departament of Neurosurgery, Copernicus Hospital, Gdansk - Poland ²Department of Neurology and Neurosurgery, Faculty of Medical Sciences, University of Warmia and Mazury, Olsztyn - Poland ³Department of Quality of Life Research, Medical University of Gdansk, Gdansk - Poland ⁴University of Physical Education and Sport, Gdansk, Gdansk - Poland

Introduction: Study reports outcomes of intrathecal baclofen (ITB) therapy for spasticity management in patients in whom failed oral therapy and who had received ITB treatment and are under control in Department of Neurosurgery in Copernicus Hospital in Gdansk. Our study was compared with similar examination: “Long-term Intrathecal Baclofen: Outcomes after More than 10 Years of Treatment” performed by Sunjay N. et al. Materials and Methods: 37 Patients underwent surgery, stay under control and surveyed a psychological examination. Spasticity was measured in Modified Ashworth Scale (MAS) before and after procedure. Psychological examination included: Cantril Ladder (CL), Intrathecal Baclofen Survey (ITBS), Satisfaction with Life Scale (SWLS), The Illness Perception Questionnaire (B-IPQ), Brief Pain Inventory (BPI), Modified Hospital Anxiety and Depression (HADS-M), that Patients had fulfilled before and after surgery. Results: The difference in spasticity and ITBS before and during ITB therapy was statistically significant. Mean MAS was reduced for 25,57%. Correlations between CL and both: SWLS (r = 0,53; p < 0,05) and BPI (r = 0,53; p < 0,05) were positive and statistically significant. Conclusions: ITB therapy is safe efficient and acceptable treatment in spasticity reduction. It increases satisfaction with life and decreases pain and anxiety. Outcomes were similar with compared study.

P299 - Correction Of Spinopelvic Parameters By Minimal Invasive Transforaminal Lumbar Interbody Fusion In Low Grade Isthmic Spondylolisthesis

Amr El-Adawy¹, Tarek ElHewala¹

¹Spine Unit, Department of Orthopedic, Faculty of Medicine, Zagazig University, Zagazig - Sharkia - Egypt

Introduction: Lumbar spinal fusion has been used to treat symptomatic patients with isthmic spondylolisthesis after failure of conservative treatment. Instrumented fusion has corrected the deformed spinopelvic parameters in these cases due to the ability of pedicle screws to reduce and maintain the reduction till the fusion occurs. Supported by some growing evidence, the main advantages of percutaneous pedicle screws are the avoidance of unnecessary muscle disruption and soft tissue dissection with decreased blood loss and faster recovery with less hospital stay. Controversy remains about the ability of the percutaneous instrumentation to reduce and maintain the slippage till fusion occurs in these segments. The purpose of this study is to evaluate the safety, and technical challenges of minimal invasive transforaminal lumbar interbody fusion (MI-TLIF) in the management of low grade L5-S1 isthmic spondylolisthesis and to study its effectiveness in correcting the deformed spinopelvic parameters that occur with these patients. Material and Methods: In this prospective cohort study, twenty-four patients with low grade L5-S1 isthmic spondylolisthesis with axial low back pain and/or leg pain were treated with minimal invasive transforaminal lumbar body fusion augmented with percutaneous pedicle screw fixation. The operative data (blood loss, radiation exposure and operative time) were evaluated and the radiological assessment for reduction and the changes in spinopelvic parameters, lumbar lordosis and correction in local kyphotic angle, slip degree and slip angle were studied on standing long films X-ray. The patient functional outcome was evaluated using Oswestry Disability Index (ODI), visual analogue scale (VAS) for back and leg pain. Patients’ satisfaction with the procedure was recorded. Results: The estimated blood loss and operative time were reduced by the increase in learning curve. Local bone graft from the removed facet joint and parts of the lamina was used with PEEK cages to obtain interbody fusion and the fusion rate at the final follow up was about 95.83% according to the radiographs. There was a significant correction in the slip degree and the slip angle in comparison to the preoperative data. Post-operative correction of the spinopelvic parameters, till nearly normal values, was obvious and was maintained throughout the follow up. No major wound related complication was reported. One case showed backward displacement of the cage with no neurological deterioration and without affecting the final outcome. ODI and VAS of back and leg pain were significantly reduced postoperatively when compared the preoperative data. Conclusion: Minimal invasive TLIF with local bone graft has been shown to be a good modality in reducing isthmic spondylolisthesis and correcting the deformed spinopelvic parameters. Cost effectiveness of this technique must be evaluated thoroughly with the final and late outcome in these cases. More randomized controlled and comparative studies with open TLIF are needed to support these findings.

Navigation

P300 - Role of 3D C-Arm Based Navigation in Anterior Surgical Excision of Osteoid Osteoma of C 6 Body: Technical Report

Ankit Patel¹, Arvind Kulkarni¹, Navin Mewara¹, Rahul Prakash¹

¹Department of Orthopaedics & Spine Surgery, Bombay Hospital, Mumbai – India

Introduction: An osteoid osteoma of the cervical vertebral body is rare and carries a surgical risk because of the close anatomic relationship to vital structures. We report the case of a 20- year-old male with an osteoid osteoma of the C6 body abutting the spinal canal causing intractable pain. Computed tomograms showed an oval nidus and marked sclerosis around this lesion at the right posterior corner of C6 body. Material and Methods: Owing to concerns regarding thermal damage to the spinal cord, nerve root, and vertebral artery using CT-guided radiofrequency ablation, we curetted the nidus using a 3D C-arm based intra-op scan integrated with an optical navigation system through a minimal access anterior cervical exposure. The patient reference array was affixed to the left clavicle using a threaded pin facilitating the procedure. Results: Twelve months after surgery, the pain was relieved with no limitation of cervical movement and there has been no evidence of recurrence. Precise and complete excision of the lesion is possible with preservation of adjacent structures thus resulting in better outcomes. Conclusion: Navigation allowed safe curettage of the nidus through a small hole while maintaining spinal stability. Navigation is feasible in anterior approaches to cervical spine with this novel patient reference array placement using threaded pin on clavicle.

P301 - Dorsal Fusion as Correction of Craniocervical and Atlantoaxial Instability in Patients with Benign and Malignant Lesions Using O-Arm System

Nikolay Mirchev¹, Robert Behr¹, Orlin Pavlov¹, Karlis Doze¹

¹Department of Neurosurgery, Klinikum Fulda gAG, Fulda - Germany

Introduction: A retrospective and prospective analysis of the surgical treatment and results of 118 patients with benign and malignant craniocervical, atlantoaxial and high cervical lesions operated during 60 – month period (2011-2016) 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: We analyzed 84 patients with traumatic lesions, 10 patients with inflammatory lesions, 8 patients with degenerative instability, and 16 patients with high cervical tumors. Results: In 118 patients we performed 132 operations. We used posterior cervical, and craniocervical median approach. Because of craniocervical/cervical instability we made posterior screw fixation in all of 118 patients. In order to improve screw placement accuracy we performed intraoperative O-Arm in 102 cases. The operative duration was 2.15 h. in O-Arm operations and 4.35 h in C-arm operation. The blood loss was 300 ml in O-Arm and 550 ml in C-Arm procedures. The mean screw length in C1/C2 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 5 cases, screw misplacement - in 2 cases (in C- Arm procedures) without early operative mortality. The 12-monts follow-up showed good recovery in 79 patients, moderate disabling – 25 patients, severe disabling – 5 patients, vegetative state – 4 patients, death 5 patients with malignant lesions. Conclusion: Early correction of craniocervical and high cervical instability facilitated neurological recovery by preserving the existent neurological function. Using of O-Arm increase operative screw placement accuracy, and preserve intraoperative nerve and vertebral artery injury. Recently because of the improvement of neuroimaging techniques, operative approaches, surgical techniques and neurointensive care the results of treatment of these lesions are optimal.

P302 - Error Propagation in Spinal Intra-Operative Navigation From Non-Segmental Registration: A Prospective Cadaveric and Clinical Study

Daipayan Guha¹, Raphael Jakubovic², Zaneen Jiwani³, Michael Fehlings¹, Albert Yee⁴, Victor Yang¹

¹Division of Neurosurgery, University of Toronto, Toronto - Canada ²Department of Biomedical Physics, Ryerson University, Toronto - Canada ³Biophotonics and Bioengineering Laboratory, Sunnybrook Health Sciences Centre, Toronto - Canada ⁴Division of Orthopedic Surgery, University of Toronto, Toronto - Canada

Introduction: Computer-assisted navigation may guide spinal instrumentation. Current systems rely on a dynamic reference frame (DRF) for image-to-patient registration and tool tracking. Displacement of levels distant to the DRF may generate inaccuracy from intersegmental mobility. Here, we quantify navigation inaccuracy due to distance from the registered level, due to surgical manipulation, and due to intra-operative patient respiration-induced vertebral motion. Material and Methods: Navigation error due to distance from the DRF, and vertebral motion during screw tract formation, were quantified in 4 human cadavers. An optical navigation system was registered through a posterior midline exposure. Bone screws were implanted into the laminae bilaterally from C2 to S1. The tip of a tracked awl was placed into the screw head at each level, at 0-5 levels distant from the registered level, and the tool tip position on the navigation system was compared to that of the screw head on post-procedure CT imaging. To quantify vertebral motion from surgical manipulation, the position of the tracked awl was quantified before and after exertion of force to create pilot holes for pedicle screw tracts, from C2-S1. Respiration-induced vertebral motion was quantified from 13 in-vivo clinical cases of open posterior instrumented fusion. Patients were positioned prone on a Wilson frame, with Mayfield head clamp for cervical fusions. The 3D position of a spinous-process clamp was tracked by OTI navigation over 12 respiratory cycles. Results: Significant increases in translational navigation error were seen with increasing distance from the registered level, with an increase in overall 3D error greater than 2 mm at 3 or more levels distant from the DRF. The increase in 3D error was predominantly in the medio-lateral axis (1.78 ± 0.86 mm, 2.78 ± 0.86 mm, 2.19 ± 0.92 mm, and 3.08 ± 0.89 mm, at 2, 3, 4 and 5 levels distant to the DRF, respectively)(mean ± SD) and antero-posterior axis (1.40 ± 0.81 mm, 1.79 ± 0.81 mm, 2.18 ± 0.87 mm, and 4.30 ± 0.84 mm, at 2, 3, 4 and 5 levels distant to the DRF). Manipulation during screw tract formation caused displacement predominantly in the medio-lateral (0.71 ± 0.84 mm) and cranio-caudal planes (1.02 ± 0.92 mm)(mean ± SD). Medio-lateral displacement was greater in the thoracic spine than in the cervical spine (0.96 ± 0.91 mm and 0.45 ± 0.30 mm, respectively), while cranio-caudal displacement was greater in the lumbar vs. cervical and thoracic spines (1.38mm ± 1.12 mm, 0.92 ± 0.82 mm, and 0.82 ± 0.72 mm, respectively). Peak-to-peak respiration-induced absolute vertebral motion was maximal in the antero-posterior (2.42 ± 1.77 mm) and cranio-caudal axes (0.92 ± 0.69 mm)(mean ± SD). Absolute antero-posterior displacement was greater in the lower thoracic spine (4.64 ± 1.45 mm) than in the cervical (2.14 ± 1.70 mm) or lumbar spine (1.50 ± 0.74 mm)(mean ± SD). In multivariate regression, both tidal volume and end-expiratory pressure were positively correlated with antero-posterior and 3D displacement. Conclusion: Vertebral motion is unaccounted for during image-guided surgery when performed at levels distant from the DRF. While respiration- and manipulation-induced vertebral motion are typically small, they can be greater than 2 mm in up to 37% of cases in our study. Navigation error from distance from the DRF alone is greater than 2 mm at 3 or more levels from the DRF. Surgeons may mitigate these errors intra-operatively by placing the DRF adjacent to the registered level; temporary apnea may be warranted at critical stages of the procedure.

P303 - Quantification of Computational Geometric Congruence in Surface-Based Registration for Spinal Intra-Operative Three-Dimensional Navigation

Daipayan Guha¹, Raphael Jakubovic², Albert Yee³, Victor Yang¹

¹Division of Neurosurgery, University of Toronto, Toronto - Canada ²Department of Biomedical Physics, Ryerson University, Toronto - Canada ³Division of Orthopedic Surgery, University of Toronto, Toronto - Canada

Introduction: Computer-assisted navigation (CAN) may guide spinal instrumentation, and requires alignment of patient anatomy to imaging. Iterative-Closest-Point algorithms register anatomical and imaging datasets, which may fail in the presence of significant geometric symmetry (congruence), leading to failed registration or inaccurate navigation. We computationally quantify geometric congruence in posterior spinal exposures, and identify predictors of potential navigation inaccuracy. Material and Methods: Midline posterior exposures were performed from C1-S1 in four human cadavers. An optically-based CAN generated surface maps of the posterior elements at each level. Maps were reconstructed to include bilateral hemilamina, or unilateral hemilamina with/without the base of the spinous process. Maps were fitted to symmetrical geometries (cylindrical/spherical/planar) using computational modelling, and the degree of model fit quantified based on the ratio of model inliers to total points. Geometric congruence in a clinical setting was assessed similarly, in 11 patients undergoing midline exposures in the cervical/thoracic/lumbar spine for posterior instrumented fusion. Results: In cadaveric testing, increased cylindrical/spherical/planar symmetry was seen in the subaxial cervical spine relative to the high-cervical and thoracolumbar spine (p < 0.001). Inclusion of the base of the spinous process decreased symmetry independent of spinal level (p < 0.001). Registration with bilateral vs. unilateral hemilamina did not significantly reduce geometric symmetry. In clinical testing, increased cylindrical/spherical/planar symmetry was again seen in the subaxial cervical spine relative to the thoracolumbar spine (p < 0.001), and in the thoracic spine relative to the lumbar spine (p < 0.001). Symmetry in all geometries was decreased by 20% with inclusion of the base of the spinous process vs. without. Conclusion: Geometric congruence is most evident at C1 and the subaxial cervical spine, warranting greater vigilance in navigation accuracy verification. At all levels, inclusion of the base of the spinous process in unilateral registration decreases the likelihood of geometric symmetry and navigation error, important for minimally-invasive unilateral approaches.

P304 - Surgeon, Staff, and Patient Radiation Exposure in Minimally Invasive Transforaminal Lumbar Interbody Fusion: Impact of 3D Cbct-Based Navigation in Comparison to Conventional Fluoroscopy Aided Technique

Ankit Patel¹, Arvind Kulkarni¹, Navin Mewara², Rahul Prakash², Mehul Sarkar¹

¹Department of Orthopaedics & Spine Surgery, Bombay Hospital, Mumbai - India

²Department of Orthopaedics & Spine Surgery, Bombay Hospital, -

Introduction: Symptomatic unstable degenerative conditions of lumbar spine are treated with spinal fusion. The minimal access technique of Transforaminal lumbar interbody fusion (MIS TLIF) is increasingly used but has been found to generate increased radiation exposure. 3D C-arm devices are capable of providing conventional 2D fluoroscopic images as well as 3D image sets for intraoperative navigation. This study was designed to compare the radiation exposure between these two intraoperative imaging techniques in MIS TLIF. Material and Methods: Retrospective analysis of prospectively collected data. 54 patients operated for single level MIS TLIF (2011-17) were allocated to one of two groups with respect to the applied intra-operative imaging technique: conventional fluoroscopy (FLUORO group) and 3D Cone-beam CT based navigation (3D NAV group). 36 patients were in FLUORO group and 18 in the 3D NAV group. Radiation exposure was measured from the time of positioning of the patient to the end of the procedure both for navigated and non-navigated freehand instrumentations. Endpoint being radiation exposure to the surgeon and is measured by numerical exposure readings directly from the Arcadis-Orbic 3D c-arm. Results: The accumulated radiation exposure for the surgeon was significantly higher in the non-navigated group, average 2.18 times (p < 0.001). The radiation exposure to the patient was higher with the 3D NAV technique 109.66 sec versus 57.57 sec (FLUORO) reaching a statistically significant level. Surgeon-Staff received only 24% of the total radiation generated in the OR. Use of 3D NAV resulted in 54.27% reduction in exposure to the surgeon-staff compared to the Fluoro group. Conclusion: Intraoperative 3D-CBCT navigation for MIS TLIF is technically feasible and reliable with reasonable set up time. It helps the surgeon-staff to escape the harmful radiation to a significant level with added advantage of increased accuracy aided by Multi-planar reconstruction.

P305 - Computed Tomography- Based Navigation System in the Surgical Treatment of Osteoid Osteoma of Spine

Alvaro Silva¹, Manuel Valencia¹, Carlos Thibaut¹, Bartolome Marré¹, Ratko Yurac¹, Felipe Novoa¹, Juan José Zamorano¹, Cristhian Herrera¹, Guillermo Izquierdo¹

¹Clinica Alemana - UDD, Santiago - Chile

Introduction: Osteoid osteoma (OO) is a small osteogenic benign tumor which is rarely found in the spine. The typical clinical setting includes intense local or regional night pain which typically alleviates with nonsteroidal anti-inflammatory drugs. Treatment alternatives include conservative and surgical management. Percutaneous techniques like radiofrequency ablation have shown good results for lesions in the appendicular skeleton. However its use to treat spinal osteomas can damage nearby neural tissues, such as nerve roots. Open en bloc resection of the nidus is a curative treatment, but it can cause spinal instability requiring reconstruction. This is why less invasive resection techniques using intraoperative computed tomography (CT) assisted navigation are an attractive alternative to achieve complete resection, while avoiding the need for spinal reconstruction. The purpose of this study is to describe the use of intraoperative computed tomography-assisted navigation guidance for less-invasive or conservative surgery, achieving a lesion-free margins resection in 3 patients with OO of the spine. Material and Methods: We reviewed the clinical records and imaging of the 3 patients (one female and two males, 24, 27 and 32 years old) with an OO of the spine operated using CT-assisted navigation in our institution during the year 2016. The location of the OO was the right T2-T3 facet joint (T2 inferior facet) in one patient, the right L1-L2 facet joint (L2 superior facet) in one patient and the right L2-L3 facet joint (L2 inferior facet) in the other patient. Because of their location, all the nidus were partially hidden from direct view and close to the nerve root, which contraindicated the use of radiofrequency ablation. The 3 patients reported long lasting back pain (mean 15 months), refractory to pharmacological treatment. Using virtual navigation based on intraoperative CT scan we pinpointed the location of the OO and defined a broad area for high speed drilling resection. The intraoperative anatomical area of resection was done without a direct view of the nidus. Anatomical broad margins around the OO, but with facet joint preservation were achieved in the 3 patients and no spinal reconstruction was needed. Results: None of the patients presented surgery-related complications, they all returned to their normal activities two weeks after the procedure and the follow up was 9, 16 and 18 months. No recurrence of pain and no segmental instability was observed. Pathology analysis confirmed the diagnosis of OO in the 3 patients. Conclusion: Total resection of a vertebral nidus without destabilizing the spine can be technically difficult in many cases. The classic en bloc resection ensures the complete removal of the nidus, but usually requires spinal reconstruction, increasing the procedure’s morbidity. The use of emerging imaging technologies, such as intraoperative navigation, is a key element to help us achieve the goal of a conservative resection with secure margins and without destabilizing the spine.

P306 - A New Classification of Pedicles Based on Technical Complexity of Screw Insertion Assessed by Airo® Intraoperative Ct Navigation in Complex Spinal Deformity

S Rajasekaran¹, Manindra Bhushan², Siddharth Aiyer³, Ajoy Shetty⁴, Rishi Mugesh Kanna⁵

¹Chairman, Dept of Orthopaedics, Trauma & Spine Surgery, Ganga Hospital, Coimbatore - India ²Spine Fellow, Department of orthopaedics, Ganga Hospital, Coimbatore - India ³Senior Registrar, Dept of Orthopaedics, Ganga Hospital, Coimbatore - India ⁴Senior Spine Consultant, Dept of Orthopaedics, Ganga Hospital, Coimbatore - India ⁵Associate Consultant, Dept of Orthopaedics, Ganga Hospital, Coimbatore - India

Introduction: Pedicle screw insertion in complex spinal deformity is challenging, and is complicated by morphometric limitations of pedicle dimensions, altered anatomical landmarks for insertions and abnormal orientation in space. AIRO® navigation systems have reported excellent screw placement however, accuracy in the clinical scenario of complex spinal deformity has not been reported previously. The purpose of this study is to develop a classification based on the technical complexity encountered during pedicle screw insertion and to evaluate the performance of AIRO® CT navigation system based on this classification, in complex spinal deformity. Materials and Methods: A prospective study was performed on 31 patients undergoing complex spinal deformity correction surgery using posterior pedicle screw instrumentation. There were 24 patients with scoliosis and 7 with kyphosis with an average cobb angle of 68.3° (range 60°-104°). Pedicles were classified according to complexity of insertion into five types: type1- normal anatomy, primary surgery and no deformity, type 2- deformity surgery, revision lumbar surgery, type 3-revision cervical and thoracic surgery, altered pedicle anatomy, congenital deformity, type 4- pedicle screw insertion unsafe without navigation due to complex trajectory, type 5- pedicle unfit for screw insertion. Analysis was performed to estimate the accuracy of screw placement, time for screw insertion and radiation exposure. Breach greater than > 2 mm were considered for analysis. Critical breach was considered to be > 4 mm, non critical breach was between 2-4 mm. Results: Total of 452 pedicle screws were inserted [T1-T6: 116; T7-T12: 171; L1-S1: 165]. We had 242 grade 2 pedicles, 133 grade 3, 77 grade 4 and 44 pedicles were unfit for pedicle screw insertion. There were total of 27 screws with pedicle breach noted, including 10 medial, 16 lateral and 1 anterior wall breach. No case was clinically symptomatic for malpositioned pedicle screw. Among Medial breach (n = 10) only 1 screw had a critical breach needing revision and 9 screws had non critical breach. Among lateral breach (n = 16), 10 screws were planned for in-out pedicle screw insertion. After accounting for planned breach, the effective breach rate was 3.8% resulting in 96.2% accuracy for pedicle screw placement. In all cases, we were able to scan whole of the planned instrumented levels in one single scan. Average screw insertion time was 1.76 ± 0.89 minutes (range 0.42- 5.35 minutes). Average radiation exposure to the patient was 4.85 ± 1.18 mSv (range 2.24-9.42 mSv). Conclusion: Studies comparing accuracy of different forms of navigation have an inherent flaw; in that the technical difficulty of screw placement, depending on the disease pathology and pedicle morphology is not standardized. To overcome this deficiency in literature, we have devised a classification with 5 types of increasingly complex pedicle screw insertion scenarios. This will allow for comparison on studies using different navigation based technologies and results from various institutions. The study also assessed accuracy of AIRO in technically challenging pedicles for screw placement. We found an accuracy of 96.2% and found AIRO to be safe and useful in complex spinal deformity.

P307 - Intraoperative Cone-Beam Computed Tomography and Navigation in Sacroiliac Joint Arthrodesis

Robert Lee¹, Vijay Rajamani¹

¹Department of Spinal Surgery, Royal National Orthopaedic Hospital, Stanmore - United Kingdom

Introduction: The anatomy of the sacroiliac joint (SIJ) is extremely variable and patients with transitional and complex anatomy can make SIJ fusion very challenging. Traditionally SIJ fusion with transverse cages is performed with 2D fluoroscopy and is reliant on identifying the alar line. Patients with deformities or anatomical variations can make identification of this key anatomical landmark nearly impossible and hence the use of transverse cages can be contraindicated in these cases. Even in ‘simple’ cases, the anatomy of the sacroiliac joint can be difficult to appreciate and the recommended cage insertion position may in fact lead to a malpositioned cage. The use of intraoperative cone-beam computed tomography and navigation allows accurate assessment of the anatomy and safe insertion of the guide wire and cages without danger to neurovascular structures. We present our series of 16 patients (17 fusions) who presented with both simple and complex anatomy. We describe our surgical technique and the essential role of navigation in simple and complex cases. Materials and Methods: This study is a retrospective review of prospectively collected data from a single surgeon series. The surgical technique is described together with radiographic review of pre and post-operative radiographs and CT scans. Predicted cage position on fluoroscopy is compared to position on CT. Retrospective review of prospectively collected data with minimum 6 month follow-up. Results: All patients had the navigation frame inserted into the contralateral PSIS. A universal navigated drill guide was used, once the 3D scan was acquired, to insert guide wires across the SIJ, followed by cage insertion. 2D fluoroscopy was also used to compare the classically described entry point to the one demonstrated on navigation. In every case the position of the most cranial cage was more posterior than would be expected. In two cases, patients had extremely challenging anatomy with deformities which would have precluded the insertion of transverse cages. Both patients underwent successful fusion. None of these patients have required revision and there has been no neurological injury. Conclusion: The use of intraoperative cone-beam computed tomography and navigation can overcome anatomical challenges in the SIJ and allow more accurate insertion of transverse cages. Even in ‘simple cases’, the placement of sacroiliac cages may not be what would be expected using fluoroscopy alone.

P308 - Robotic Assisted Fixation of Sacral Fractures – Initial Experience

Schroeder Josh¹, Leon Kaplan¹, Bilal Qutteineh¹, Yoram Weil¹, Meir Liebergall¹

¹Hadassah University Hospital, Jerusalem - Israel

Introduction: Unstable sacral fractures are challenging for orthopaedic trauma surgeons. In most cases percutaneous fixation techniques are utilized after reduction. However, these techniques are not risk free mainly due to anatomical considerations. Screw misplacement is quite common and concerning. As spine surgery evolved, a miniature robotic guidance system was successfully utilized in pedicular screw insertion. The aim of the study was to demonstrate the use of the miniature robot in the fixation of unstable sacral fractures. Material and Methods: Patients and Methods: 10 patients with unstable sacral fractures without significant displacement were eligible for percutaneous fixation. These included 8 traumatic fractures and 2 pathological fractures. Nine fixation constructs were planned using a preoperative CT scans and one case was done with an intraoperative CT. The patients were placed prone and the robot was mounted on a Dynamic Reference Bridge (DRB), in cases of the preoperative CT-2 verification fluoroscopic images were taken in the case of the intraoperative imaging a 3D scan was performed intraoperative after fracture reduction. The robot was mounted on the DRB and was sent by the robotic computer to the desired screw(s) trajectory. The guide wires were inserted through stab wounds and screws were placed subsequently. CT scans were made postoperatively and fluoroscopic and operative time were recorded intraoperatively. Results: Mean patient age was 29 (17-63) number of screws ranged 1-8 (average 2.5). Mean operative time was 50 min (range 15-90), and average fluoroscopic time was 18 sec (7-42). None was the screws was misplaced. Conclusion: Robotic assisted fixation of sacral fracture is promising. In displaced fractures intra operative reduction and fixation can be used as well.

Nonoperative Clinical Treatments

P309 - Clinical Efficacy of Selective Nerve Root Block in Lumbar Radiculopathy due to Disc Prolapse: Outcome Analysis in the Nepalese Population

Gaurav Raj Dhakal¹, Yoshiharu Kawaguchi¹

¹National Trauma Center, Kathmandu - Nepal

Introduction: Although studies have shown benefits with steroid injections in lumbar disc herniation with radiculopathy in the short term, however, most of them involved epidural injections. We are not aware of any study demonstrating the efficacy of selective root block in lumbar radiculopathy due to a herniated disc in the Nepalese population. Material and Methods: The recently validated Nepali version of the Oswestry Disability Index Questionnaire was used to analyze the effects of transforaminal steroid injections in 41 patients with lumbar disc herniation and radiculopathy. Patients with leg pain, positive straight leg raising test and single level disc prolapse on MRI were included. Patients with profound motor sensory weakness, cauda equina syndrome, previous spine surgery and injections were excluded. The procedure was performed under fluoroscopic guidance and assessment was done pre-injection, 1 week, 1 month, 6 months and 1 year post injection. Results: 41 patients (m = 23) with a median age of 38 years with lower limb radiculopathy were included in the study. 23 had left leg pain and 25 patients had disc prolapse at L4L5; 14 at L5S1; 2 at L3L4. The mean VAS score preinjection was 8.024 ( ± 0.85) and ODI was 33.2 ( ± 6.8); 1 week post injection mean VAS reduced to 4.6 ( ± 1.84) and mean ODI 21.2 ( ± 9.16); 1 month mean VAS score 2.7 ( ± 1.06) and mean ODI 12.7 ( ± 4.56); 6 months mean VAS 2.3 ( ± 0.75) and mean ODI 9.8 ( ± 2.87); 1 year VAS 2.6 ± 0.84) and ODI 10.03 ( ± 2.97). One week after the first injection 6 patients underwent surgery due to unrelieved pain. Paired t test was applied for statistical significance (p < 0.05) and the reduction in pain VAS score and ODI score between preinjection and 1 week, 1 month, 6 months and 1 year was statistically significant however the reduction in pain and ODI score between 6 months and 1 year was not statistically significant. Conclusion: Selective Nerve Root Block in lumbar radiculopathy significantly reduces the pain up to a year, however, the reduction in pain plateaus around six months duration. Because of the cultural and language barrier, validated cross cultural outcome questionnaire should be used in the assessment.

P310 - Impact of a Newly Developed Flexion Orthosis on Clinicial Parameter in Patients with Neurogenic Claudication. A Prospective Randomized Trial

Klaus John Schnake¹, Sylvia Schreyer¹, Catherine Disselhorst-Klug²

¹Center for Spine and Scoliosis Surgery - Schön Klinik Nürnberg, Fürth – Germany ²Dept. of Rehabilitation and Prevention Engineering, Aachen - Germany

Introduction: Conservative treatment of neurogenic claudication includes physical therapy and epidural steroid injections. The effects of wearing a lumbar orthosis are unclear. The purpose of this study was to examine the clinical effects of a newly developed lumbar flexion orthosis in patients with neurogenic claudication due to spinal stenosis. Material and Methods: Prospective randomized study. 30 patients suffering from neurogenic claudication due to lumbar spinal stenosis were enrolled. Twenty patients (mean age 62.7 years, 12 male, 8 female) used a newly developed lumbar flexion orthosis over a period of 21-28 days. 10 patients (mean age 71.7 years, 3 male, 7 female) served as control group without any intervention. Clinical tests with 6 standardized elements of relevance in everyday life (standing upright, standing bent forward, trunk rotation, stairs up and down, chair rising and 6 minutes walking test) were performed at baseline and at the end of the follow-up period. The European Questionnaire for Quality of Life in 5 Dimensions (EQ-5D), Zurich Claudication Questionnaire (ZCQ), Oswestry Low-Back Pain Disability Index (ODI), pain measured by visual analogue scales (VAS) and analgesics use were assessed. Results: Follow-up rate was 100%. There was a significant and clinical relevant improvement in the 6-minute walk test with a mean increased walking distance of 13.3%. The chair-rising and stairs-up-and-down tests also showed a clear positive effect with a mean improvement of 27.6% and 18.8%, respectively. All 5 self-reported assessments showed an improvement in the orthosis group, especially in the ZCQ, ODI and pain VAS, whereas the control group showed a tendency towards deterioration. Thus, the new dynamic lumbar flexion orthosis contributes to improvements in performance in important activities of daily living, such as walking, sitting down and getting up, and climbing stairs. Conclusion: The tested orthosis showed a significant and clinical relevant effect on the walking distance in patients with neurogenic claudication due to lumbar stenosis. Positive effects were seen in all used assessments.

P311 - Triple Modalities Guide Nerve Block and Radiofrequency Ablation for Lumbosacral Pathologies-Treatment Rationale, Technical Note and Literature Review

Ting Chun Huang¹

¹National Taiwan University Hospital Chu-Tung Branch, Hsinchu County - Taiwan, Province of China

Introduction: Discomfort at waist and peributtock regions are of high prevalence; however, multiple pathologies including facet, sacroiliac joint(SI), sacral radiculopathy and multiple tissue including osseous, ligamentous and neurogenic need to be deferentiated. Additional to history, physical examination and imaging, nerve block(NB) serves a deterministic diagnostic tool and radiofrequency ablation(RF) serves as a minimally invasive treatment for these patients. This study aims to introduce NB and RF under sonoguide, electric stimulation and fluoroscopic validation of contrast median distribution as a method of diagnosing and treating lumbosacral pathologies. Material and Methods: Retrospective case series of 100 cases (SI arthrosis, Facet arthrosis, Lumbo-sacral Radiculopathy) from single hospital by single surgeon (author) from 2016/07 to 2018/05. Preoperational plain film were collected. SF-36, JOA score and ODI were recorded preoperatively and postoperatively(immediate postop, 1 month, 3 month and 6 months). NB was performed in outpatient setting for facet, sacroiliac joint pathologies with only sonoguide and was performed in operating room for lumbarsacral radiculopathy. After NB relief partial of patients symptoms which recurred one week after. Patients was arranged for Radiofrequency ablation under local anesthesia(0.1mg/ml Marcaine) in the operation room after electric stimulation confirm the location of nerve (0.3 mA). No sedation was used and heart rate and blood pressure was controlled with oral medications. C-arm Fluroscopy and sonography (curvelinear probe) were utilized the location, electrical stimulation was used to confirm with the patient and epidural contrast spread was checked under fluoroscopy. Non-parametric statistical methods were applied(Mann-Whitney U test). Results: SF-36, JOA score and ODI all revealed significant differences comparing before NB and after NB and after RF. Clinical photo of surgical markings, fluoroscopic and ultrasound pictures will be shown in the presentation. Conclusion: Case series has its limitation of no control group and its subject to bias. Limited followup time was also need improvements. S1-4 NB from S1-4 foramen was best performed under fluoroscopic guidance with caudal deviation about 30 degrees. with electric stimulation, patients can inform surgeon if the stimulated feelings matched the pathologies to differentiate whether pain was origin from sacroiliac joint, facet or sacral radiculopathy. SI block for SI region pain is useful and intraarticular injection is not needed. Medial branch block for facet pain is very useful but need to monitor the spread of medication to avoid affecting lumbar roots.

P312 - Comparison of Radicular Blockage Efficacy in Patients with Foraminal Lumbar Disc Hernia

Thiago Maia¹, Charbel Jacob Jr¹, Igor Machado Cardoso¹, José Lucas Batista Jr¹, Marcus Alexandre Novo Brazolino¹, Diego Caldas¹, Eduardo Correa Damazio¹, Ricardo Sturzeneker Cerqueira Lima¹

¹Department of Orthopedics, Santa Casa de Vitoria, Vitoria - Brazil

Introduction: This research aims to evaluate the improvement of pain and functional outcome in patients with lumbar disc hernia undergoing transforaminal blockade. To relate the obtained results, comparing the different types of agents and associated vehicles in the medications most used for the technique. Materials and Methods: A prospective, longitudinal study of the comparative type. After the MRI examination, 60 patients underwent transforaminal root blockade. Three drugs of the corticosteroid class were used: Betamethasone, Dexamethasone and Triamcinolone. The medications were administered in a randomized, triple blind manner. Patients were divided into three groups of 20 subjects each: group 1 - Betamethasone 3 mL (4 mg / mL) + 2 mL anesthetic; group 2 - Dexamethasone 2.5 mL (4 mg / mL) + 1 mL (2 mg / mL) + 1.5 mL anesthetic; group 3 - Triamcinolone 2 mL (20 mg / mL) + 3 mg anesthetic. Functional and pain assessment questionnaires were applied serially (pre, 1 and 6 months after the procedure). Results: Group 1 presented mean AVA in the preoperative period of 8.05 after 1 month of 5.45; after 6 months 5.578. Roland Morris preoperative mean value of 19.10; after 1 month of 14.30; after 6 months 13,21. Oswestry mean preoperative value of 27.65; after 1 month of 21.85; after 6 months 20,89. Group 2 presented mean AVA in the preoperative period of 8.65; after 1 month of 5,10; after 6 months 5,777. Roland Morris pre-operative average of 19.10; after 1 month of 12.00; after 6 months 13,27. Oswestry medium preoperatively of 23.40; after 1 month of 15.65; after 6 months 16,50. Group 3 presented mean AVA in the preoperative period of 8.80; after 1 month of 6.95; after 6 months 5,888. Average Roland Morris in the preoperative 18,20; after 1 month of 16.05; after 6 months 13,44. Oswestry medium preoperatively of 27.55; after 1 month of 21.95; after 6 months 25 555. Conclusions: in the long term there was no significant difference in the results presented by the different compounds evaluated, which leads us to think that criteria such as cost and rate of side effects should be given greater importance when the selection of the compound to be used in the transforaminal block.

Novel Technologies

P313 - Computer-assisted Patient Specific Prototype Template for Thoraco-lumbar Cortical Bone Trajectory Screw Placement: Cadeveric Study

Yougun Won¹

¹Harvard Medical School Orthopedic Trauma Initiative, Boston - United States

Introduction: For improvement of holding screw strength with less invasive exposure, a cortical bone trajectory (CBT) screw technique reports effective mechanical and clinical results. Accurate and safe placement of screw is crucial. A patient-specific drill template with pre-planned trajectory has been thought as a promising solution, it is critical to assess the efficacy, safety profile with this technique. The goal of this study is to evaluate the accuracy of patient-specific CT-based rapid prototype drill guide templates for thoraco-lumbar CBT technique. Material and Methods: The volumetric CT scanning was performed in 7 cadaveric thoraco-lumbar spines and a three-demensional (3D) reconstruction model was generated. Using the computer software, the authors constructed the drill templates that fit onto the posterior surface of thoraco-lumbar vertebrae with drill guides to match the cortical bone trajectory. Eighty guide templates from T12 to L5 were created from the computer models using a rapid prototyping machine. The drill templates were used to guide drilling of the trajectory of cortical bone screw without any fluoroscopic control and the CT images were obtained after fixation. The entry point and direction of the planned and inserted screws were measured and compared. Results: In total, 80 screws were inserted from T12 to L5. No misplacement or bony perforation was observed by postoperative CT scan. Conclusion: Using the patient specific prototype template system demonstrates the clear advantage in safe and accurate cortical screw placement of thoraco-lumbar spine. This method has shown its ability to customize the patient-specific trajectory of thoraco-lumbar spine, based on the unique morphology. The potential use of drill templates to place thoraco-lumbar cortical bone trajectory screws is promising.

Keywords: drill template, cortical bone screw, computer assisted template, rapid prototyping

P314 - Three Columns Vertebrotomies in Extra-Apical Area as a Method of Surgical Deformity Correction of Cervicothoracic Transition: Analysis of the Clinical Series and Literature Data

Egor Filatov¹, Sergey Riabykh¹, Dmitry Savin¹

¹Ilizarov Centr, Kurgan - Russian Federation

Introduction: Retrospective analysis of the treatment results of the patients with malformation and segmentation of the cervical and upper thoracic vertebrae. Material and Methods: Retrospective multi-center cohort of 8 cases aged from 8 to 15 years. Inclusive criteria are as follows: children aged less than 15 years by the time of operation, deformity in the frontal plane, application of three columns vertebrotomy and complete radiological archive availability. Results: Patients with multiple abnomalies with a leading component maldevelopment of vertebral segmentation and formation are predominated. There were no violations of sagittal balance in patients. The amount of scoliotic deformity according to Cobb ranged from 30° to 66° (mean value - 46.1°), with a frontal imbalance in 6 (55.5%) patients. After operations scoliosis values were from 3° to 34° (mean value - 15.3°). However in all cases after operation the frontal balance was restored. The amount of correction ranged from 49% to 90% (mean 69.4%). No permanent neurological complications were observed in peri- and post-operative periods. Conclusion: The key criterion for surgical correction of the defects of the cervicothoracic transition is the reconstruction of the local balance in the frontal and sagittal planes, and not the absolute correction of local deformation. Spine osteotomy in extra-apical area in children with multiple mal-developments of the cervical and upper thoracic spine allows us to produce adequate deformity correction (for mean 69.4%) and to reduce the risk of neurological disorders through main compression manipulation. That reduces the zone of instrumental fixation which is important for preservation of the axial growth.

P315 - Relationship between Opioid Use and Outcomes in Patients Undergoing Basivertebral Nerve Ablation for Chronic Low Back Pain

Peter Vajkoczy¹, Rick Sasso², Alfred Rhyne³, Alpesh Patel⁴, Wellington Hsu⁴, Jeffrey Fischgrund⁵

¹Klinik für Neurochirurgie, Berlin - Germany ²Indiana Spine Group, Carmel - United States ³OrthoCarolina Spine Center, Charlotte - United States ⁴Department of Orthopaedic Surgery Northwestern University, Chicago - United States ⁵Beaumont Orthopaedic Center, Royal Oak - United States

Introduction: Opioid dependency is a social problem reaching near epidemic proportions in the U.S., with over 20 000 prescription opioid related overdoses observed in 2015.¹ Opioids may be used to manage pain in certain patients diagnosed with chronic low back pain (CLBP); ideally, alleviation of CLBP may affect consumption of opioid pain relievers. Materials and Methods: Opioid use was monitored in a randomized clinical trial (SMART) to investigate the effect of basivertebral nerve (BVN) ablation on CLBP. The primary outcome variable in the trial was the observed change in ODI at 3 months; a statistically significant decrease in ODI was observed in the treatment group.² Opioid medication use history was collected at each follow-up interval and subsequently converted to opioid equi-analgesic weekly dose; at each follow-up time point individual use was categorized as unchanged, increased, or decreased. After the conclusion of the study, we compared the average change in ODI and VAS in the treatment group patients who increased as opposed to decreased use of opioid medication at 3 months. Results: Short acting opioids were used at time of enrollment by 57 out of 145 patients on an intent-to-treat (ITT) basis and 48 out of 127 patients on a per-protocol (PP) basis. At the three month primary endpoint, the mean improvement in ODI and VAS in patients increasing and decreasing their use of opioids was compared. These metrics were statistically and measurably inferior in patients reporting an increased use of opioids as shown in Table 1. Conclusions: Patients who increased their consumption of opioid medications following RF ablation of the BVN for relief of CLBP had poorer outcomes measured using ODI and less pain relief measured using VAS than did patients with constant or decreasing use of opioids. These data suggest that there exists a relationship between decreased functional and pain outcomes and increased use of opioid pain relievers in patients with CLBP, and that relieving chronic back pain may be a factor in reducing opioid usage.

Table 1.

Comparison of ODI and VAS at 3 months in patients who increased and decreased their use of opioids. Values represent a decrease from baseline.

Metric	Increased OP Use	Decreased OP Use	p value
ODI (ITT Basis)	10.6 ± 8.0 (n=18)	18.7 ± 13.7 (n=29)	0.03
ODI (PP Basis)	10.6 ± 9.0 (n=14)	20.9 ± 13.9 (n=24)	0.02
VAS (ITT Basis)	0.87 ± 1.5 (n=18)	2.7 ± 2.3 (n=29)	0.004
VAS (PP Basis)	0.8 ± 1.5 (n=14)	3.0 ± 2.2 (n=24)	0.002

References

1. Rudd et al., Increases in Drug and Opioid Involved Overdoses 2010-15, http://dx.doi.org/10.15585/mmwr.mm655051e1

2. Fischgrund et al., NASS, 2016

P316 - Satellite Rod Technique Around Rod-Breaking Area in Revision Surgery after Three-Column Osteotomy: A Minimum of 2 Years Follow-Up

Zezhang Zhu¹, Benlong Shi¹, Xu Sun¹, Zhen Liu¹, Yong Qiu¹

¹Department of Spine Surgery, Drum Tower Hospital, Nanjing University Medical School, Nanjing - China

Introduction: To evaluate the radiographic and clinical outcomes of satellite rod technique used around the rod-breaking area in the revision surgery due to rod fracture after three-column osteotomy within a minimum of 2 years follow-up. Materials and methods: Eleven patients (7 males and 4 females) applying satellite rod technique in the revision surgery from December 2012 to March 2015 were retrospectively reviewed. The average age of the cohort was 27.3 years. The coronal parameters including Cobb angle and distance between C7 plumb line and center sacral vertical line (C7PL-CSVL), and the sagittal parameters including global kyphosis (GK) and sagittal vertical axis (SVA) were assessed at pre-revision, post-revision and last follow-up. The paired t test was used to analyze the difference among pre-operation, post-operation and last follow-up. Results: The average follow-up period was 29.2 months. The Cobb angles at pre-revision and post-revision were 38.4 ± 21.1° and 32.0 ± 19.9°, respectively (P = 0.003). The average correction rate was 20.3% ± 14.4%. At last follow-up, the average Cobb angle was 31.9 ± 14.2°, and there was no significant loss of correction (P = 0.439). Post-revision C7PL-CSVL changed from19.0 ± 19.7 mm to 20.1 ± 14.7 mm (P = 0.864), of which the average value was 22.4 ± 18.3 mm at last follow-up (P = 0.786). The pre-revision and post-revision values of GK were 23.8 ± 24.8° and 19.0 ± 22.1° with the average correction rate being 23.7% ± 19.0% (P = 0.176). At the last follow-up, the average GK was 22.1 ± 21.4° and the correction was well maintained (P = 0.254). In terms of SVA, the average values were 51.2 ± 40.1 mm for pre-revision, 30.7 ± 16.7 mm for post-revision, and 31.2 ± 12.9 mm for last follow-up. Improvements were observed at post-revision though the difference between pre-revision and post-revision was not significant (P = 0.644). All patients responded to the SRS-22 questionnaire and all the domains showed improvement in different levels. In addition, there was no complication of implant failure during follow-up and all patients achieved solid bony fusion. Conclusions: The satellite rod technique used around the rod-breaking area in the revision surgery due to rod fracture in patients undergoing three-column osteotomy could get satisfied clinical and radiographic outcomes. With the utilization of satellite rod technique, the coronal and sagittal balance could be well maintained during follow-up.

Keywords: satellite rod; spinal deformity; rod fracture; revision

P317 - The Significance of Upper Extremity Neuromonitoring Changes in Patients Undergoing Thoracolumbar Surgery

Kivanc Atesok¹, Walter Smith¹, Gerald McGwin¹, Thomas Niemeier¹, Jason Pittman¹, Sakthivel Rajaram¹, Steven Theiss¹

¹Department of Orthopaedic Surgery, University of Alabama at Birmingham, Birmingham - United States

Introduction: Peripheral nerve injuries of the upper extremities in patients undergoing posterior thoracolumbar surgery is a well described, yet preventable complication. Upper extremity (UE) neuromonitoring has been utilized to alert the surgeon of the development of such an injury. This study investigates the significance of UE neuromonitoring changes in patients undergoing thoracolumbar surgery. Materials and Methods: All patients who underwent posterior thoracic, lumbar, or thoracolumbar surgery at a single institution from 2014-2016 with neuromonitoring were included in the study. UE neuromonitoring consisted of ulnar somatosensory evoked potentials (SSEPs). Patients with intraoperative ulnar SSEP signal changes were identified and compared with a group of pair-matched patients who did not develop intraoperative ulnar SSEP signal changes. The groups were matched based on the number of vertebral levels undergoing surgery. Data regarding intraoperative attempts to resolve signal changes and outcomes were collected. The two groups were compared to identify the risk factors for the development of UE neuromonitoring changes. Results: Between January 2014 and December 2016, 843 patients in our institution underwent thoracic, lumbar or thoracolumbar spine surgeries in prone position with intraoperative bilateral ulnar SSEPs neuromonitoring data available. Of these, 37 patients (4.4%) had intraoperative signal changes in the UE; an equal number of patients without signal changes were also selected. In each group, six patients underwent thoracic, 20 patients underwent lumbar, and 11 patients underwent thoracolumbar procedures. In eight patients (21.6%), there was no resolution of SSEP signal changes despite intraoperative attempts. The two groups were similar with respect to age and co-morbidities including diabetes, ischemic heart disease, and peripheral arterial disease. There was also no significant difference in the mean BMI (p = 0.22). The mean duration of the procedures was 324 minutes in the SSEP signal change patients and 260 minutes in the patients who did not experience SSEP signal changes (p = 0.03). No patient with UE SSEP changes had a clinically detectable neurologic deficit postoperatively. Conclusions: Upper extremity SSEP signal changes during multilevel posterior thoracolumbar procedures are more likely to occur as the duration of the operation increases. The presence of UE signal changes does not coincide with clinically significant peripheral neuropathies.

P318 - Free-Hand Placement of C7 Laminar Screws: Accuracy and Safety in 43 Consecutive Patients

Jiwon Park¹, Hyo Sae Ahn¹, Quan You Li¹, Ho-Joong Kim¹, Bong-Soon Chang², Choon-Ki Lee², Jin Sup Yeom¹

¹Spine Center and Department of Orthopedic Surgery, Seoul National University College of Medicine and Seoul National University Bundang Hospital, Sungnam-si - Korea, Republic ²Department of Orthopaedic Surgery, Seoul National University College of Medicine and Seoul National University Hospital, Seoul - Korea, Republic

Introduction: Although pedicle screws have been regarded as the first-line choice for fixation of C7, they may require radiographic or fluoroscopic guidance, take time for placement, and have a potential risk of neurovascular complications. Given such limitations, C7 laminar screw might serve as a viable alternative. However, while laminar screws are widely used for C2 fixation, reports on the clinical experience of C7 laminar screws are quite limited. The purpose of this study was to determine the accuracy and safety of C7 laminar screw placement with a free-hand technique. Material and Methods: All patients who underwent posterior cervical fixation with C7 laminar screws by the last author were chosen. All screws were placed with a free-hand technique without radiographic or fluoroscopic guidance. The operating time for each screw placement was approximately 1-2 minutes. Clinical information and radiologic data of the patients were analyzed. Using postoperative CT scans, which were taken in all patients, the accuracy of screw placement was evaluated by two orthopedic surgeons by assessing the direction (dorsal versus ventral) and degree of laminar cortical breach. Results: Forty-three consecutive patients were enrolled. There were 26 males and 17 females, and the age averaged 59 years (range, 14-82). A total of 61 C7 laminar screws were used: twenty-five patients underwent unilateral C7 laminar screw fixation, and eighteen patients underwent bilateral fixation (Figs 1 and 2). All the laminar screws were 3.5 mm in diameter and 20 to 26 mm in length (3 20-mm, 13 22-mm, 38 24-mm, and 7 26-mm screws). Of the 61 screws, 14 screws (23%) breached the laminar cortical wall, including 3 dorsal and 11 ventral breaches. Of those 14 screws, 11 screws (18%) breached by less than 50% of screw diameter and 3 screws (5%) breached by more than 50% but less than 100% of screw diameter. Nine screws were one of the screws placed bilaterally, and 5 screws were unilaterally placed. No intraoperative neurovascular injury was observed, and none of the screws with cortical breaches resulted in worsening of neurologic symptoms. None of the patients required reoperation for any reason. Over the follow-up period of 20 months, mechanical failure such as loosening or fractures of screw-rod system has not been observed. Conclusion: To our knowledge, this is the largest clinical study ever performed on C7 laminar screw fixation. Although laminar cortical breach was common (25%) with our free-hand technique, most were trivial and none had clinically relevant neurovascular complications nor mechanical failures. Therefore, C7 laminar screws, which can be placed quickly and easily without the need of radiographic or fluoroscopic guidance, may provide a valuable alternative to pedicle screws for C7 fixation in terms of efficacy and safety. However, long-term outcomes, including fusion status, remains to be evaluated with further follow-up.

P319 - Novel Technique for Treating Levine and Edwards Type II Hangman Fracture

Yuqiang Wang¹, Yilin Liu¹, Liang Zhao¹, Ruipeng Song¹, Hao Yang¹, Yang Zhang¹, Limin Wang¹

¹The First Affiliated Hospital of Zhengzhou University, Zhengzhou - China

Introduction: Hangman fracture is a fracture which involves the pars interarticularis of C2 on both sides. The treatment of Levine and Edwards type II hangman fracture is still controversial. Conservative treatment requires long-term external fixation of the neck. Surgical treatment can realize early activities, but the risk of complications are very high. It needs more appropriate surgical treatment for this injury. This research is to explore the feasibility and operative effect of posterior semi-threaded pedicle screw (Smooth shank polyaxial screws) in the treatment of Levine and Edwards type II hangman fracture. Material and Methods: A retrospective analysis of 2 cases with Levine and Edwards type II hangman fracture who were treated with semi-threaded pedicle screws only. Both patients were male. One case was 45 years old, and the other case was 18 years old. The elder patient was caused by traffic accidents, while the other was owing to falling high. Neck collar was advised for 4 weeks after surgery. Reduction of fracture and bone union were evaluated by images. The curative effect was evaluated by JOA score, VAS score and ASIA grading. Results: The average operation time was 40 min. Average amount of bleeding was less than 50 ml. There were no vertebral artery or nerve injury during the surgery. Both patients were followed up for 12 months at least. Bone fusion was confirmed by the imaging at six months after surgery. Cervical sequence and cervical function were well preserved. Neurological function were restored to normal. No neck pain or other symptoms were found on two cases. JOA score was increased from an average of 13.5 points to 17 points at the last follow-up. However, VAS score was decreased from an average of 6.5 to 0.5 at the last follow-up. ASIA spinal cord function of two patient was increased from preoperative D grade to postoperative E grade. Conclusion: Posterior semi-threaded pedicle screw can be used to treat Levine and Edwards type II hangman fracture. Semi-threaded pedicle screw could not only be used for fixing fracture, but also play the effect of compression for reduction. Using screw fixation only could be called the Judet fixation. This novel technique can retain range of motion for the cervical spine resulting in less trauma. It should be recommended.

P320 - First Clinical Experience with a Carbon/Peek Composite Plating System for Anterior Cervical Discectomy and Fusion (Acdf)

Helena Maria Milavec¹, Christoph Kellner¹, Moritz Caspar Deml¹, Naresh Kumar², Lorin M. Benneker¹

¹Spine Unit, Department of Orthopedics and Traumatology, Inselspital, University of Bern, Bern - Switzerland ²Department of Orthopaedic Surgery, National University Hospital, Singapore - Singapore

Introduction: This study assessed the efficacy and safety of anterior cervical discectomy and fusion (ACDF) with a new Carbon/PEEK anterior cervical plate system for clinical outcomes and radiographic evaluations in cervical degenerative, trauma and tumour disease. Materials and Methods: Patients with cervical degenerative, trauma or tumor disease who underwent ACDF with Icotec^© anterior cervical plate system between January 2011 and June 2016 were assessed retrospectively. All patients were evaluated clinically and radiologically before surgery and had a clinic and radiographic follow up directly after surgery and 2, 6 and 12 months postoperatively. Implant safety and failure, intraoperative management, clinical outcome, patient acceptance, and the degenerative changes in adjacent segments were examined during each follow-up examination. For radiologic assessment, we obtained lateral and anteroposterior plain radiographs and measured the sagittal segment alignment (SSA) of the operated segments and the sagittal alignment of the whole cervical spine (SACS) according to Cesare et al. Results: The final data analysis included 39 patients. The majority of patients had monosegmental ACDF (n = 23), followed by bisegmental ACDF (n = 15) and trisegmental (n = 1). Screws had good primary positioning and there was no plate- or screw fracture at 12-months follow up. 12 patients presented excellent clinical outcome, 15 good, three fair and one poor outcome. 10 patients occasionally had cervical pain at 12-months follow up, two were complaining about persistent dysphagia. In two cases revision was necessary due to complications. For analysis of SACS and SSA over a 12-month period 31 patients were available. The improvement of SACS an SSA overall between preoperative radiographs and immediately postoperative control could be shown as statistically significant (p < 0.001), whereas there was no statistically significant difference between SACS and SSA postoperative and at 12-month follow-up. At 12-months follow up-radiographs, changes in degeneration at the adjacent levels were found in 4 patients (10.3%). Interbody fusion after 12 months was graded I in 18 patients (60%), II in 5 (17%), III in 7 (23%) and grade IV was not found (according to Bridwell et al). Conclusion: The use of a PEEK plate is suitable for use in ACDF in trauma, degenerative and tumour disease. In terms of safety, clinical outcome and reliability a PEEK plate is comparable to the commonly used plating systems and comparable to the “gold standard” titanium plates.

P321 - Youtube as An Educational Platform in Orthopaedics: A Novel Grading System for Lumbar Fusion Surgery Videos

Sandip P. Tarpada¹, Matthew T. Morris¹, Woojin Cho²

¹Albert Einstein College of Medicine, Bronx, NY - United States ²Department of Orthopaedic Surgery, Albert Einstein College of Medicine / Montefiore Medical Center, Bronx, NY - United States

Introduction: Since their conception, online video platforms have increasingly been utilized within the surgical community as an educational adjunct to residency curricula. YouTube, in particular, is a commonly cited educational resource by orthopaedic surgery residents. To date, despite the growing popularity of orthopaedic surgery videos on YouTube among trainees, there exists no uniform system to evaluate these videos for educational value. Here, we propose such a grading scheme applied specifically to orthopaedic lumbar fusion videos on YouTube. Methods: A 20-point video grading scale was devised and applied to YouTube videos of lumbar fusion surgery. The grading scale took into account a number of factors, including the procedure itself, video quality, and general educational value of the video. (Figure 1). The following search terms were used to find relevant videos: “spinal fusion,” “lumbar spinal fusion,” “anterior lumbar interbody fusion,” “posterior lumbar interbody fusion,” “transforaminal lumbar interbody fusion,” “transpsoas interbody fusion,” and “oblique lateral lumbar interbody fusion.” Search terms were entered as plain text within the search box; Boolean operators were not used. The search was refined to include only videos with a run time of 20 or more minutes, found within the first 5 results pages. Videos targeting patients, from personal accounts, or created for entertainment purposes were strictly excluded. Results: A search yielded 150 non-duplicate videos. Of these, 18 remained after application of inclusion and exclusion criteria. Mean video score was 13.1 ± 2.5 points out of 20. Six videos (33%) achieved scores above 16, and were deemed as useful educational adjuncts for the orthopaedic trainee. The mean number of views for videos scoring below 16 points was 11 754.4 ± 312.1, significantly greater than that of videos scoring above 16 points (8061.1 ± 112.1; p < 0.003). Video results and grading are summarized in Table 1. Conclusion: Here, we describe a grading system for assessment of the educational value of lumbar fusion surgery videos on a globally popular online video platform. With the growing number of surgery videos available online, a verified video evaluation system such as ours can prove to be a valuable asset to the orthopaedic trainee.

Figure 1.

Video Grading Scheme.

Table 1.

Search Results.

Name of Video	Shortened URL	Score	Uploaded by	Num of views	Notes	Surgery
Anterior approach to thoracic spine - Dr Sandeep Sonone	coLsbaZY6HM	8	Individual	18 872	Surgery video with no description or narration.	Anterior lumbar interbody fusion
L5-S1 OLIF Demonstration by Richard Hynes, MD	XhsOa23fpnk	12	Institution	4049	Complete surgery with three views: fluoroscopic, surgeon’s and mid shot of surgeon. Lab.	Oblique lateral lumbar interbody fusion
Oblique Demonstration by Kamal Woods, MD	0Q-VzmXdAmc	20	Educational institution	663	Complete surgery with three views: fluoroscopic, surgeon’s and mid shot of surgeon. Lab.	Oblique lateral lumbar interbody fusion
Posterior Revision Decompression and Lumbar Fusion Surgery of the Spine	BMBNqM2PKgk	20	Individual	6080	Video shows surgery from several different angles with surgeon’s commentary and views of some films.	Posterior lumbar interbody fusion
Oblique Lumbar Interbody Fusion (Lab Demonstration) - Kevin T. Foley, MD	FmB6Dy4uI7U	20	Educational institution	675	Complete surgery with multiple views.	Transforaminal lumbar interbody fusion
Posterior Revision Decompression and Lumbar Fusion Surgery of the Spine	UJ53CtXfc3o	20	Hospital	39 395	View of surgery from several angles.	Posterior lumbar interbody fusion
Live Spine Surgery: Minimally Invasive Lumbar Fusion	BfFaVT9h194	12	Hospital	24 037	View of surgery from several angles. Vision is often poor.	Lumbar spinal fusion
Least Invasive Lumbar Fusion L45 Spondylosisthesis	4La8lGaIL9E	12	Hospital	1362	View of surgery from several angles, some of which are quite far away.	Lumbar spinal fusion
Minimally Invasive Revision Lumbar Fusion	KOBIwppxFHc	8	Hospital	537	View of surgery from several angles. No sound	Lumbar spinal fusion
ACTUAL ADR SURGERY: 2-Level Lumbar Disc Replacement Surgery Video from Enande and Dr. Ritter-Lang	Ws94agBww1Q	20	Hospital	384	Surgery in close up with voiceover	Lumbar spinal fusion
Live Spine Surgery: Percutaneous Lumbar Pedicle Screws 1-15-16	6XnwxCs93tU	12	Hospital	681	Shows surgery from several angles, however none are very useful	Lumbar spinal fusion
XLIF® Procedure- Minimally Disruptive Procedure for Spine Surgery	lXHk8I-WnZ0	8	Hospital	68 868	Basically an advertisement. Any view of the surgery itself is incidental	Posterior lumbar interbody fusion
Posterior Lumbar Stabilization	7T8t0eG8k3E	12	Individual	159	Single view of the surgery. No voice over or narration given. Surgery is complete.	Posterior lumbar interbody fusion
Minimally Invasive Spinal Surgery - Unilateral Uniportal TLIF	e0B41cI9gjI	8	Individual	1061	Single unobstructed view of the surgery with no voice over given. Not complete	Posterior lumbar interbody fusion
L5S1 lumbar discectomy	qX9S2eKKW8	8	Individual	40 787	Single unobstructed view of surgical field. No sound	Anterior lumbar interbody fusion
Least Invasive Lumbar Fusion L45 Spondylosisthesis	4La8lGaIL9E	12	Hospital	1318	View of surgery from several angles, some of which are quite far away.	Transforaminal lumbar interbody fusion
Minimally Invasive Spinal Surgery - Unilateral Uniportal TLIF	e0B41cI9gjI	12	Individual	1029	View of surgery from close up with no narration	Transforaminal lumbar interbody fusion
MIS TLIF with Dr. Greg Anderson	wevs93QRKVw	20	Hospital	1547	Surgery given from one angle, with narration and films	Transforaminal lumbar interbody fusion

P322 - Targeted Localization of Doxorubicin-Bound Nanoparticles to the Vertebral Column Using Magnetic Kyphoplasty in a Pig Model

Steven Papastefan¹, Steven Denyer¹, Abhiraj Bhimani¹, Pouyan Kheirkhah¹, Jack Zakrzewski¹, Tania Aguilar¹, Akop Seksenyan¹, Marysol Arce¹, Jack Williams¹, Andreas Linninger², Gail Prins³, Ankit Mehta¹

¹Department of Neurosurgery, University of Illinois at Chicago, Chicago - United States ²Department of Bioengineering, University of Illinois at Chicago, Chicago - United States ³Department of Pathology, University of Illinois at Chicago, Chicago - United States

Introduction: Metastatic prostate cancer with spinal metastasis is traditionally treated with radiation therapy alone or with cytoreductive surgery. Patients with prostate cancer metastasis to the spinal column are at greater risk for events that lead to neurological deficits, bone pain, and spinal instability. Subsets of patients with prostate spinal metastasis who are poor surgical candidates and fail radiation therapy are left with limited options. Kyphoplasty is a procedure utilized in this population as a palliative means of improving oncological pain through stabilization for fractured or weak vertebral bodies. Our study uses a novel in-vivo model to develop a targeted drug delivery platform for spinal metastatic prostate disease that blends minimally-invasive kyphoplasty with nanomedicine. More specifically, the purpose of this proof of concept study is to use magnet-enhanced cement kyphoplasty cement to act as a magnetic localizer for systemically delivered doxorubicin-bound iron nanoparticles (DOX-MNPs) to sites of prostate metastasis in the spine. Material and Methods: One Landrace-Yorkshire cross pig underwent a kyphoplasty procedure with Polymethyl methacrylate (PMMA) cement with neodymium-iron-boron (NdFeB) magnets placed in two separate lower thoracic vertebral bodies two levels apart. An internal control of PMMA without magnets placed in 2 separate lumbar vertebral bodies two levels apart. After 24 hours, a solution of doxorubicin-bound gold-iron oxide nanoparticles were injected into the right ear vein under guidance of a veterinarian. The pig was sacrificed 24 hours after nanoparticle injection, and the injected vertebral bodies and adjacent bodies were removed and frozen. The vertebral bodies were decalcified with hydrochloric acid for 6 hours and embedded in paraffin for sectioning at 12 μm. Prussian blue stain counterstained with nuclear fast red was employed to label the iron MNPs. Results: Our results revealed successful localization of magnetic nanoparticles to the vertebral bodies adjacent to the magnetic cement at the lower thoracic spine. No nanoparticles were present in the lumbar spine adjacent to bodies with only PMMA cement. The pig did not experience a hyperacute infusion-related reaction to the DOX-MNPs. Conclusion: This study demonstrates proof of concept that systemically-injected magnetic nanoparticles can be successfully localized to specific areas of the vertebral column using a magnet-enhanced kyphoplasty. Further development of this technique may provide an integrated surgical option for patients that provides both spinal stabilization and localized cancer treatment. Further animal studies are needed to assess long-term toxicity and to assess the efficacy of our delivery system in treating metastatic prostate cancer in a pig tumor model.

P323 - The Accuracy and Safety of Subaxial Cervical Pedicle Screw Insertion Using Vertebral Lateral Notch-Referred Technique

Kai Cao¹, Yiwei Chen¹, Junlong Zhong¹, Zhimin Pan², Pingguo Duan¹

¹Orthopedics Department, The First Affiliated Hospital of Nanchang University, Nanchang - China ²Department of Neurosurgery, Spine and Spinal Cord Institute, Yonsei University College of Medicine, Seoul - Korea, Republic

Introduction: Biomechanical studies revealed that pedicle screw instrumentation has superior stabilizing effect than other internal fixations in the reconstruction of subaxial cervical spine, particularly, in the surgery of cervical tumor resection, deformity correction and severe fracture and dislocation. However, high neurovascular risk precludes surgeons to conduct the pedicle screw manipulation in cervical spine. We here advocate a novel, easy-mastering and practical technique (as called notch-referred technique) for subaxial cervical PS insertion. In this study, the accuracy and safety of lateral vertebral notch-referred technique for subaxial cervical pedicle screw (PS) were evaluated clinically. Materials and Methods: Eighty-six consecutive patients with cervical disorders underwent cervical PS instrumentation in two spine teams in a single spine center. Preoperative X-ray, CT and MRI of cervical spine were taken for surgery plan. The pedicle screw position was confirmed by postoperative CT scans. The perforation rate was analyzed and the position of pedicle screw was classified into four grades from excellent position to poor position to assess the accuracy of this technique: Grade 0 = screw centered in pedicle (excellent); Grade I = perforation of pedicle wall less than one-fourth of the screw diameter (good); Grade II = perforation more than one-fourth of the screw diameter but less than one-second (fair); Grade III = perforation more than one-second outside of the screw diameter (poor). Neurovascular complication related with PS insertion was recorded to assess the safety of this technique. The accuracy of PS insertion between two surgeons was analyzed to confirm the manipulative consistency. Results: A total of 504 pedicle screws were inserted in subaxial cervical spine. Postoperative CT scan indicated the excellent and good position of PS by using notch-referred technique was as high as 90.9% (458/504) (Grade 0 + Grade I), the poor PS position was only 4.9% (25/504) (Grade III). There was no vertebral artery injury or spinal cord injury related with cervical PS misplacement in this cohort except one slight nerve root compression. The patient relieved from the radiculopathy in the course of follow-up without screw removal. No revisional surgery was conducted due to the misplacements of pedicle screws. The PS manipulation consistency between two surgeons was not significantly different. Conclusions: The lateral vertebral notch is the reliable and consistent anatomic landmark. The accuracy and safety of subaxial cervical pedicle screw insertion by using notch-referred technique are high and satisfactory. Notch-referred subaxial cervical PS insertion is an easy-mastering, practical technique.

P324 - Decreased Incidence of Total Blood Loss Peroperatively and Postoperatively in Revision Spinal Fusion Surgeries with Topical Application of Tranexamic Acid Compared to Intravenous Administration

Sureshkumar BC¹, A Navaladi Shankar¹

¹Department of Orthopaedics Apollo Hospitals, Chennai - India

Summary: Revision spinal fusion surgeries including TLIF, PLIF among failed back syndromes is associated with significant blood loss. Topical application of tranexamic acid (TXA) reduces calculated %total blood loss (%TBV) peroperatively and postoperatively compared to intravenous tranexamic acid administration. Hypothesis: Topical application of TXA administration reduces % TBV loss in revision spinal fusion surgeries including TLIF, PLIF compared to intravenous administration of TXA. Design: This was a retrospective comparative case-control study evaluating 50 revision spinal fusion surgeries by a single surgeon at Apollo Main Hospital, Chennai from Jan (2014) to Dec (2016). Introduction: Revision spinal fusion surgeries including TLIF, PLIF are typically associated with significant blood loss. Anti-fibrinolysis such a TXA has been proposed to reduce both blood loss (peroperatively and post operatively) and the subsequent need for blood transfusion. Methods: Efficacy of TXA was evaluated by comparing mean estimated blood loss (EBL) and %TBV loss, peroperatively and postoperatively and the requirement of blood transfusion, with clinical factors including age, sex, number of levels fused and length of operation was tested for correlation with %TBV loss. Conclusion: Topical application of TXA during revision spinal fusion surgeries including TLIF, PLIF reduced significant blood loss peroperatively and post operatively compared to intravenous TXA.

P325 - 3D Modeling and Printing Technologies in Spine Surgery: A Survey of Aospine Members

Peter Eltes¹, Laszlo Kiss¹, Marton Bartos², Zsolt Eösze¹, Peter Pal Varga¹, Aron Lazary¹

¹National Center for Spinal Disorders, Budapest - Hungary ²DO3D Innovations Ltd., Budapest - Hungary

Introduction: Computer aided engineering methods such as finite element analysis (FEA) based simulations have a huge impact on everyday clinical activity. 3D printing (3DP) due to it’s cost-effective, easily accessible manufacturing process for unique geometries, play an important role in personalized spine surgery. However, there is little information on a global perspective about the spread and approval for teaching and for clinical use among spine surgeons of the 3DP, FEA simulation, 3D virtual and physical models (3D technologies). Materials and Methods: In collaboration with AOSpine, we have performed a global, online survey-based study where we aimed to determine the acceptance rate and the factors which stand against the wider spread of the 3D technologies. Our analysis is based on the responses of 282 spine surgeons from 57 countries. To interpret our results in a global context, we used the Human Development Index (HDI) of the respondent’s countries in comparisons. Results: The results of the study shed light on significant and widespread interest among spine surgeons towards the incorporation of these 3D technologies in the clinical practice. However, we found a significantly higher difference between the AOSpine regions, with the highest approval in the Asia-Pacific region. The attitude towards the technology varied based on the respondent’s resident country’s HDI score and was significantly different between „medium” vs “very high” and “high” vs “very high” HDI category. The role of education, healthcare and the economic environment is highlighted by the significant positive correlation between the acceptance of 3D technology and the HDI. There was no significant difference in acceptance score when comparing the responses according to the field of spine surgery, or when grouped by the surgical experience in years. The reported main limitations towards regular use of 3D technologies were the lack of accessibility and high costs. Conclusion: Our results also provide the basis of a strategy to promote the application of 3D technologies on a wider scale that has to focus on development of more cost effective technology and delivery of know-how.

P326 - Expandable Anterior Lumbar Interbody Fusion Cages – Early Clinical and Radiographic Results and the Ability to Fine Tune Adjacent Segmental Lordosis

Robert Lee¹

¹Department of Spinal Surgery, Royal National Orthopaedic Hospital, Stanmore - United Kingdom

Introduction: The potential benefits of expandable anterior lumbar interbody fusions include the ability to increase very collapsed disc height and provide finer control of lordosis. Controlled expansion may also prevent subsidence. Some of the controversies include possible compromise of the area for bone grafting and the justification for the increased cost of these implants. There is little evidence for expandable ALIF cages. This paper aims to address these controversies and present our early experience with these expandable ALIF cages. Materials and Methods: This is a retrospective review of prospectively collected data of a single surgeon case series of 17 patients. Pre and post-operative radiographic parameters: Lumbar lordosis (LL), Pelvic Incidence-Lumbar Lordosis mismatch (PI-LL), Sagittal Vertical Axis (SVA), Pelvic Tilt (PT) and segmental lumbar lordosis at adjacent levels were measured. Outcome scores included VAS Back, VAS leg, EQ-5D and Oswestry Disability Index (ODI). Patients were followed up at 6 weeks, 6 months and 1 year. Patients had CT scans at either 6 months or 1 year to assess fusion. Results: A total of 21 cages in 17 patients were inserted. These included standalone single level ALIFs, two level ALIFs with posterior fusion, ALIF combined with TLIF, degenerative scoliosis correction and spondylolisthesis correction. There were 17 L5/S1 ALIFs and 4 two level L4/5 and L5/S1 ALIFs. 7 patients have had CT scans to assess fusion and all show evidence of fusion through the cage. Clinical Results at 6 months show an average reduction in VAS Leg 8.4 to 1.0, VAS Back 8.1 to 1.4, ODI 64 to 22 and an increase of EQ-5D 0.357 to 0.856. In 8 patients, the pre-operative radiographs showed no mismatch between lumbar lordosis and pelvic incidence but the levels adjacent to the degenerate discs showed compensatory lumbar lordosis such that lordosis was abnormally distributed in the lumbar spine. The use of expandable cages in these cases allowed fine tuning of the lordosis such that postoperative compensation at these adjacent levels was eliminated. This is showed in the figures below. Conclusion: Our early experience of expandable ALIF cages shows excellent early outcomes, good fusion through the cage and the ability to fine tune lordosis at levels adjacent to the degenerate disc. It is hoped that this will lead in the long term to less adjacent level failure and the additional cost will reduce the need for revision surgery.

P327 - How Can a Novel Hybrid Spine Surgery Simulator Distinguish between Different Experience Levels?

Simon Weidert¹, Matthias Mayr¹, Axel Greiner¹, Christopher Becker¹, Wolfgang Böcker¹, Bianka Rubenbauer¹, Felix Achilles¹

¹Orthopedic Trauma Department, University of Munich, München - Germany

Introduction: Being able to safely insert a needle through the spinal pedicles is a core skill in spine surgery training and is a key step in many procedures such as kyphoplasty or spinal fusion. While the apprenticeship model is still the major training principle in most departments, simulation is promising to improve training with a safe and effective means to educate future spine surgeons. In our study, we aim to determine how a novel hybrid simulator for spine surgery can distinguish between different skill levels. Material and Methods: Two groups were defined with novices and experienced surgeons ( > 10 pedicle procedures within the last half year). A prototype of a spinal surgery simulator consisting of a 3D-printed spine specimen of L2 to L4, artificial skin and soft tissue as well as an electromagnetic tracking system with real instruments was used. A 15 min. video instruction about the technique and the objectives as well as a learning program about the C-arm controls was provided. Subsequently, one of the three spinal levels was randomly assigned to each participant. After localizing the vertebra with the radio-opaque tool and virtual fluoroscopy using a foot pedal, the C-arm joints had to be moved until fluoroscopy showed an ideal projection of the vertebra. The Jamshidi needle was inserted percutaneously onto the bone surface until the tip position was regarded ideal on biplanar fluoroscopy. The tool was advanced either using a hammer or by pushing and turning the tool with the hand while carefully observing fluoroscopy. The test subjects were free to indicate when final position was obtained. Each test subject completed two pedicle placements. All simulated procedures were videotaped and the simulator automatically recorded several metrics such as time, number of fluoroscopy images, instrument path as well as correct vertebra and pedicle breach grade. Matlab was used for a 3D review of the tool path and for the computation of P-values. Results: Seven experienced and ten novice surgeons (n = 17) were recorded performing the simulated surgery. Total procedure time was less than half in the experienced group (median: 08:03 min vs. 16:32 min, p = 0.02). Furthermore, the novices showed a much higher number of pedicle breaches (1xB, 3xC, 3xE, Gertzbein-Robbins) compared to only one B-grade breach in the experienced group. There was no significant difference between the experienced and novice group regarding the number of images taken during the procedure (median: 98 vs. 87, p = 0.84). Conclusion: Realism and proper determination of skill level are fundamental requirements for any simulation technology. While realism is highly subjective, relevant metrics for skill determination must be well defined and are ideally acquired in an automatic and objective manner. This can be done by a hybrid simulator merging the “real” haptic feeling of real instruments and synthetic bone with the “virtual” imaging of fluoroscopy and instrument tracking. Our study shows that overall performance of experienced surgeons is clearly superior when compared to novices, especially regarding primary outcome parameters such as pedicle breaches and procedure time.

P328 - Fmwand in Posterior and Lateral Surgery for Spinal Deformities: Clinical and Radiological Study

Alessandro Ramieri¹, Giuseppe Costanzo²

¹Don Gnocchi Foundation, Milan - Italy ²Orthopaedics. Sapienza University, Roma - Italy

Introduction: The ferromagnetic dissection (FMd), is based on inductive high frequency magnetic fields able to cut, ablate and vaporize the tissue, obtaining a highly hemostatic effect. FMd in spine surgery is a technological innovation. Materials and Methods: We used the FMd by FMwand for posterior approach of 40 different types of scoliosis and 25 spondylolisthesis. All these procedures involving the use of evoked potentials. The FMd was used also for diskectomy during XLIF. We recorded surgical time and blood loss, comparing the data with other 60 spinal defomities (group B), prepared by monopolar/bipolar electrical devices (Mpd). Post-operatively, we evaluated tenderness, swelling, bruise of the paravertebral tissue. Post-operative MRI for the paravertebral muscle evaluation was obtained at 14 days, 1 and 3 months after surgery. Results: In group A, the mean preparation time was 19 minutes (range 17-55), while in group B was 37 minutes (range 27-78) (p < 0.01). In group A, mean blood loss was 58 cc (range 30-80) and in group B 84 cc (50-150) (p < 0.05). Tenderness/swelling showed no particular differences. Evoked potentials showed no abnormalities during FMd and an electrical silence was always recorded. In XLIF, cutting and ablation of the annulus were quick, more than with mechanical tools. Conclusion: In vivo studies established that FMd decreases damages to the paraspinal muscles, edema or postoperative scar. Our original application to paravertebral muscles in spinal deformities showed positive results in terms of surgical time and bleeding. The absence of electrical stimulation did not affected intraoperative monitoring. Incision and ablation of the annulus were more rapid compared to that performed with mechanical instruments. On MRI, damage of muscles and paravertebral tissue seems to be more severe after MPd.

P329 - Posterior Subaxial Cervical and Cervicothoracic Joint Spine Fixations: Recommendation From a Intraoperative Neurophysiological Monitoring Point of View

Juan Pablo Cabrera C.¹, Francisco Luna A.¹, Esteban Torche V.¹, Walter Rivas W.¹, Máximo Torche V.¹, Sebastián Vigueras A.¹, Rubén Muñoz C.¹, Guillermo Valdés I.¹

¹Department of Neurosurgery, Hospital Clínico Regional de Concepción, Concepción - Chile

Introduction: Posterior cervical and cervicothoracic joint fixations are necessary surgeries in context of trauma and degenerative. Cervical myelopathy is often present, and worsening of motor and sensory function can occur despite using Intraoperative Neurophysiological Monitoring (IOM) and experienced hands. However, to our knowledge, there is not a recommendation regarding when to place and lock rods during instrumentation, as exist in tumoral and deformity surgeries. Objective: Demonstrate the advantage and timing of instrumentation during posterior cervicothoracic spine surgeries. Material and Methods: Prospectively collected and retrospectively reviewed study since August 2012 to September 2017. We have analized the cases of posterior cervical and cervicothoracic joint surgeries, of trauma and degenerative, with or without instrumentation, in which IOM was used. Craniocervical (C0-C2) and lower levels than T2 were excluded. Results: Total of surgeries 34, 17 (50%) laminectomy alone or laminoplasty and 17 (50%) decompression plus instrumentation. All patients have been studied with CT scan and MRI before surgery. In 4 patients were necessary to change the position of the head subsequent to an IOM warning (11.8%). IOM alerted for MEP and/or SSEP decreasement 8 patients (23.5%): 6 did not develop new neurological deficit, of them 4/6 decompressed before rods placed; and 2 had significant clinical impairment (5.9%), these last 2 patients without instrumentation. In 3 patients (8.8%) IOM were unrecordable secondary to myelopathy or anesthesia. Four patients had IOM improvement comparing to baseline (11.8%), all of them placing rods before decompression. Conclusion: In our experience, posterior cervical and cervicothoracic joint spine surgeries are benefit by instrumentation rather than posterior decompression alone. Our recommendation from an IOM point of view is to place and lock rods before to perform decompression, in order to avoid neurological worsening.

Spine Biologics

P330 - Lumbar Interbody Fusion Rates in 3D Printed Lamellar Titanium Cages Using a Silicate Substituted Calcium Phosphate Bone Graft

Michael Mokawem¹, Robert Lee¹, Clare Harman¹

¹Spinal Surgery Unit, Royal National Orthopaedic Hospital, Stanmore - United Kingdom

Introduction: The use of lumbar interbody cages in minimally invasive adult deformity and degenerative surgery allows restoration of sagittal and coronal balance, provides neural decompression (indirect and direct) and can achieve a 360-degree fusion. Successful long-term outcomes are dependent on achieving a solid fusion. This is dependent on cage material, cage design, bone graft used as well as surgical technique. Moreover, it is harder to achieve fusion in multilevel surgery. We present a case series of 78 patients who had a combination of either transforaminal or lateral interbody 3D printed lamellar titanium cages packed with silicate substituted calcium phosphate bone graft. No iliac crest bone graft was harvested. We achieved a 99% fusion rate at 12 months. Material and Methods: This study is a review of prospectively collected data from a single surgeon consecutive case series of 78 adult patients with lumbar degenerative disease or deformity requiring anterior column reconstruction. Transforaminal Lumbar Interbody Fusion (TLIF) and Lateral Lumbar Interbody Fusion (LLIF) cases were included. All cases had 3D printed lamellar titanium cages with silicate substituted calcium phosphate bone graft. All patients had their reconstruction augmented with posterior instrumentation or a lateral plate. Outcome measures: 1. Radiological: All patients had CT scans at 12 months to assess fusion. CT scans were reported by a consultant musculoskeletal radiologist and independently reviewed by both authors. 2. Patient reported: EuroQol-5Dimension (EQ-5D), EQ-5D Visual Analogue Scale (VAS), VAS Leg Pain, VAS Back Pain and Oswestry Disability Index (ODI) were collected at 6 weeks, 6 months and 1 year. Results: Case mix was as follows: 25 single level TLIF (14 cases at L4/5, 10 at L5/S1, 1 at L2/3), 14 two level TLIFs (6 cases at L3/4 and L4/5 and 8 cases at L4/5 and L5/S1), 39 LLIF cases with 79 cages (11 cages at L1/2, 22 cages at L2/3, 30 cages at L3/4 and 16 cages at L4/5). 12 Patients had two lateral cages inserted and 10 patients had 3 or more lateral cages in the correction of degenerative scoliosis. CT scans showed solid fusion in all but one case with good integration of the cage at the vertebral body interface and no evidence of screw loosening. The one case of pseudoarthrosis was in a two level TLIF in a grade 2 spondylolisthesis with fusion at L4/5 and pseudoarthrosis at L5/S1. Patient reported outcomes showed significant improvements at 1 year: EQ-5D from 0.312 to 0.916, EQ-5D VAS from 47.9 to 80.35, VAS Leg Pain from 7.55 to 1.75, VAS Back Pain from 7 to 2.15 and ODI from 56.25 to 21.7. Conclusion: Our study demonstrates that excellent fusion rates can be achieved with 3D printed lamellar titanium cages and silicate substituted calcium phosphate bone graft even where multilevel interbody cages are used. We believe that the excellent fusion rates significantly contribute to the improvement in patient reported outcomes. The increased cost of the bone graft compared to autologous bone graft is justified due to the increased rate of fusion and the decreased morbidity.

P331 - Nanoparticles for the Delivery of Zoledronate to Bone Metastasis Secondary to Prostate Cancer

Elie Akoury¹, Bardia Barimani¹, Pouyan Ahangar¹, Karl-Philippe Guerard², Jacques Lapointe³, Lisbet Haglund³, Derek Rosenzweig³, Michael Weber³

¹Department of Experimental Surgery - Division of Orthopedics, The Research Institute of the McGill University Health Centre, Montreal - Canada; ²Department of Surgery, Division of Urology, The Research Institute of the McGill University Health Centre, Montreal - Canada; ³Department of Surgery, McGill University, Montreal - Canada

Introduction: Up to 80% of patients with primary tumors of the breast, prostate or lung will develop spine metastases. These bone metastases cause chronic pain, functional deficit and severely diminished health related quality of life. Available therapies include radio-chemo-therapy, hormone therapy and surgery. Surgical resection of metastatic bone tumors leads to large bone defects, instability and poor bone repair. Another current treatment that is being explored involves bisphosphonates (BP) -such as Zoledronate [Zol]- which act not only as osteoclast inhibitors reducing bone resorption, but also as a direct anti-tumor compound inhibiting tumor growth. The use of BP for cancer therapy is currently limited to intravenous infusion to achieve the dose required for efficacy. However, such procedure can cause severe side effects such as renal toxicity. Interestingly, our group has shown that local BP delivery blocks tumor-induced osteolysis while preventing the occurrence of side effects associated with systemic administration. Over the past decades, nanoparticles have emerged as an exciting method for delivering anti-cancer drugs directly to tumor sites, which allow for high and local administration while avoiding the complications of systemic delivery. Our aim is to develop a valuable tool that delivers BP locally for enhanced bone repair while attempting to inhibit cancer recurrence in patients with bone metastasis secondary to prostate cancer. Material and Methods: Nanoparticle-BP preparation: we incubated fluorescent Zol overnight with mesoporous nanoparticles that were either uncoated or coated with a thin chitosan shell. The nanoparticles were dispersed in physiological media. Aliquots from the dispersed solution were taken daily for up to 10 days. Small samples of particles were observed by fluorescence microscopy, while eluted Zol was measured using a plate reader. Testing Zol in vitro: we have obtained commercially available prostate cancer cell lines and isolated tumor cells of spinal bone metastasis from patients with primary prostate cancer undergoing surgery. To test the metabolic activity and proliferation, each cell line and the patient tumor cells were seeded, incubated with non-fluorescent Zol for different time points. Metabolic activity and proliferation rate are then assessed using the alamarBlue® and MTT assays respectively. Results: Our results show that chitosan-coated nanoparticles hold and release more BP over time in aqueous media compared to uncoated nanoparticles. Testing the effect of Zol on different prostate cancer cell lines in vitro shows significantly reduced proliferation and metabolic activity after 48 hours of BP treatment, in a dose dependent manner. Assessing the effect of nanobead release of Zol on prostate cancer cell lines and patient derived cells is ongoing. Conclusions: Nanoparticles releasing Zol could constitute a therapeutic promise to combat metastatic spine tumors secondary to prostate. These nanoparticles can be integrated into commercial bone putty to develop a bioactive bone graft following bone tumor resection to deliver localized bisphosphonate drug facilitating bone stability and healing while preventing tumor recurrence.

P332 - Back Pain Improvement after Cost-Effective Posterior Midlinedecompression with Postero-Lateral Fusion with Autologous Morselised Bonegraft with Bmac Aspirateapplication in Elderly Patients with Severe Degenerative Spinal Canal Stenosis

A Navaladi Shankar¹

¹Department of Orthopaedics, Apollo Hospitals Chennai - India

Summary: Significant back pain improvement among the elderly aged between 60years to 70years who underwent posterior midline decompression with posterolateral fusion with autologous morselised bonegraft with bmac aspirate application and its cost effectiveness compared to instrumentation.

Hypothesis: Elderly patients with significant preoperative back pain with degenerative spinal canal stenosis respond well with significant improvement in back pain with the cost effective posterior midline decompression with postero-lateral fusion with autologous morselised bonegraft with BMAC aspirate application.

Design: This was a retrospective study evaluating clinically along with post operative pain score compared to preoperative pain score among the elderly patients aged between 60years to 70years who underwent posterior midline decompression with postero-lateral fusion with autologous morselised bonegraft with bmac aspirate application, by a single surgeon at Apollo Main Hospital, Chennai from Feb 2015 to Jan 2017.

Introduction: Elderly patients with degenerative spinal canal stenosis with severe back pain who generally require fusion surgery with instrumentation, respond well with simple posterior midline decompression with posterolateral fusion with autologous morselised bonegraft with BMAC aspirate application, considering its cost effectiveness, decreased surgery timing and early rehabilitation. Methods: Elderly patients categorised between 60years to 70years with significant back pain who were diagnosed degenerative spinal canal stenosis, categorised according to age, sex and levels involved, who underwent posterior midline decompression with postero-lateral fusion with autologous morselised bonegraft with BMAC aspirate application were followed up during the 1st, 3 rd, 6th and 12months and compared with the pain score and clinically, showed significant improvement. Conclusion: Simple cost effective posterior midline spinal decompression with postero-lateral fusion with BMAC aspirate application among elderly patients diagnosed with degenerative spinal canal stenosis, respond very well clinically with improved pain score with decreased surgery timing and early rehabilitation and very cost effective than spinal fusion surgeries requiring instrumentation.

P333 - Effectiveness Evaluation of Platelet-Rich Plasma in the Bone Consolidation of Patients Submitted to Lumbar Arthrodesis

Thiago Maia¹, Charbel Jacob Jr¹, Igor Machado Cardoso¹, José Lucas Batista Jr¹, Marcus Alexandre Novo Brazolino¹

¹Department of Orthopedics, Santa Casa de Vitoria, Vitoria - Brazil

Introduction: Knowing the importance of adequate bone healing for the success of vertebral arthrodesis surgery and the various existing limitations to the use of autologous grafts, an increase in studies with the use of bone substitutes associated with hydroxyapatite (HA), bone protein (BPM) and platelet rich plasma (PRP), among the aforementioned materials with osteoinductive properties PRP has been described in the literature as one of the most widely used and currently researched. The aim, therefore, is to determine if the use of autograft associated with platelet-rich plasma (PRP) increases bone healing in patients undergoing lumbar fusion. Materials and Methods: A prospective, descriptive and comparative study, with 40 patients undergoing lumbar fusion. They were divided into two groups: group I only autograft and group II autograft associated with PRP. After surgery, the monitoring was held on the first, third and sixth month. The Molinari radiographic and Glassman tomographic classifications were used as criteria to analyze the bone consolidation. Results: Comparing the Group I with Group II, it was observed that in the first month after surgery, according to the criteria of Molinari, bilateral fusion was 27.5% for the group I. In the third and sixth month, bilateral fusion was 25.0% and 20% for group II, respectively. And based on the results of CT scans performed at six months after surgery, according to the criteria of Glassman, bilateral solid fusion was 15.0% and 10.0% in groups I and II respectively. Conclusions: It was observed that the use of PRP showed no significant difference in bone healing lumbar arthrodesis.

Surgical Complications

P334 - Preoperative Steroids for Intramedullary Spinal Tumors Do Not Affect 30-Day Reoperation and Readmission Rates: A Nsqip Analysis

Abhiraj Bhimani¹, Morteza Sadeh¹, Darian Esfahani¹, Gregory Arnone¹, Steven Denyer¹, Jack Zakrzewski¹, Pouyan Kheirkhah¹, Tania Aguilar¹, Kate Louise Milan¹, Ankit Mehta¹

¹Department of Neurosurgery, University of Illinois at Chicago, Chicago - United States

Introduction: Intramedullary spinal cord tumors (IMSCTs) account for 8-10% of all spinal cord tumors and affect patients of all ages. Although uncommon, IMSCTs carry risk of neurological morbidity and mortality, with 5-year survival rates ranging from 50 to 80%. In this study, we utilize the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database to determine the effect of steroid administration on 30-day outcomes following surgery for IMSCTs. Material and Methods: ACS-NSQIP data for patients undergoing surgery for intramedullary tumors from 2005 to 2015 was reviewed. Patients were selected based on CPT codes 63 285 (Laminectomy, intradural, intramedullary, cervical), 63 286 (Laminectomy, intradural, intramedullary, thoracic), and 63 287 (Laminectomy, intradural, intramedullary, thoracolumbar). ICD-9 and ICD-10 codes were chosen based on the diagnosis of a tumor. 30-day clinical outcome data, including reoperations and readmission rates were collected and compared. Results: 259 patients were reviewed. 181 patients had benign intramedullary tumors and 78 had malignant intramedullary tumors. The majority of IMSCTs were at the thoracic level (n = 100), followed by cervical (n = 99), and thoracolumbar (n = 39). 31 patients were on corticosteroid therapy prior to surgery. Patients with preoperative steroid administration had no significant difference in reoperation and readmission rates. No significant differences were noted between steroid vs. non-steroid therapy for discharge destination, length of hospital stay, or other postoperative complications. Conclusion: Corticosteroid use prior to surgery for IMSCTs does not have a significant impact in 30-day risk of readmission, reoperation, and risk of postoperative complications.

P335 - Intra-Operative Neuro-Monitoring Availability During Surgery in Patients with Thoracic Spine Deformities

Sergey Ryabykh¹, Marat Saifutdinov¹, Dmitry Savin¹, Olga Pavlova¹

¹Ilizarov Center, Kurgan - Russia

Summary of background data: Spinal deformity correction in patients with affected thoracic spine is hidden with a relatively high risk of postoperative neurological deficit.

Objectives of the study: To systematize the electrophysiological changes during thoracic spine surgery and to develop new scale of intraoperative neurophysiological testing of the pyramidal tract. Materials and methods: We analyzed 318 protocols of intraoperative neuromonitoring of 288 patients (107 males, 181 females), aged from 1.3 years old to 27 years old (12.6 ± 0.35 years old) who underwent surgery in thoracic spine followed by different types of spine osteotomies and pedicle screw fixation. Intraoperative neuromonitoring was performed by «ISIS IOM» (Inomed Medizintechnik GmbH, Germany) system. The changes of motor evoked potentials (MEP) were evaluated according to our new scale. Results: Five types of pyramidal system reaction to operative invasion were revealed. According to neurophysiological criteria three grades of the risk of neurological deterioration during surgery were defined. The frequency of changes of MEP, indicating the danger of iatrogenic lesions, depended on the age of the patient and did not exceed 10% of cases. Conclusion: Intraoperative neurophysiologic monitoring allows the surgeon and anesthesiologist to correct their actions during surgery and it minimizes the danger of iatrogenic neurological deterioration. Our new grading system of MEP changes in the intraoperative neurophysiologic testing of the pyramidal tract, allows quantifying the risk of neurological disorders in patients during thoracic spine surgery.

P336 - Rate of Instrumentation and Fusion-Related Complications after Surgical Treatment for Severe Pediatric Spinal Deformity Within 2 Years: A Prospective Multi-Center Cohort Study

Munish Gupta¹, Lawrence Lenke², Jahangir Asghar³, Oheneba Boachie-Adjei⁴, Patrick Cahill⁵, Mark Erickson⁶, Sumeet Garg⁶, Peter Newton⁷, Amer Samdani⁸, Suken Shah⁹, Harry Shufflebarger¹⁰, Brenda Sides¹, Paul Sponseller¹¹, Daniel Sucato¹², Michael Kelly¹, Fox Pediatric Spinal Deformity Study Group¹

¹Department of Orthopaedic Surgery, Washington University School of Medicine, St. Louis - United States

²Department of Orthopedic Surgery, Columbia University Hospital, New York, NY - United States

³Orthopedics, Miami Children’s Hospital, Miami, FL - United States ⁴FOCOS Orthopaedic Hospital, Accra - Ghana ⁵Orthopaedic Surgery, Children’s Hospital of Philadelphia, Philadelphia, PA - United States

⁶Orthopedic Surgery, Children’s Hospital, Aurora, CO - United States ⁷Orthopaedic Surgery, Rady Children’s Hospital, San Diego, CA - United States ⁸Shriners Hospitals for Children, Philadelphia, Philadelphia, PA - United States ⁹Orthopaedic Surgery, Nemours Alfred I. duPont Hospital for Children, Wilmington, DE - United States ¹⁰Orthopedics, Nicklaus Children’s Hospital, Miami, FL - United States ¹¹Orthopaedic Surgery, Johns Hopkins University, Baltimore, MD - United States ¹²Orthopaedic Surgery, Texas Scottish Rite Hospital, Dallas, TX - United States

Introduction: Severe pediatric deformity can be extremely challenging to treat due to difficulties with instrumentation placement in small patients, stress on implants due to correction of severe deformities, and use of three column osteotomies. This study analyzed the instrumentation and fusion related complications in complex spine deformity surgical cases. Hypotheses: pediatric patients with severe spinal deformities treated surgically have a high rate of revision surgery for instrument and fusion related complications. Material and Methods: This was a prospective observational multi center cohort of pediatric patients having surgical treatment for severe spinal deformity ( > 100° or planned VCR). 176 patients with severe complex spinal deformity were included from a prospective database with a min. 2 year follow-up. Complications with or without revision due to pseudoarthrosis, instrumentation failure, infection requiring instrumentation removal and progression of deformity were all analyzed. Results: 176 patients out of 313 pts reached a minimum of 2 years follow up. 21 patients (12%) had complications associated with the instrumentation. 15 patients (9%) required 16 revision surgeries because of instrumentation failure. 6 patients (3%) had complications but did not require any revisions. The 16 revision surgeries included 7 (43%) with loss of fixation. The average time for the revision surgery was 13 months (0-28) after the index surgery. Only one patient had 2 revisions. 4 patients were revised for pseudarthrosis at an average of 23 months (17-35). 2 patients (13%) had revisions for prominent instrumentation (both at 27 mos postop), 2 (13%) for infection (19 and 36 months respectively), and one patient had revision surgery for deformity progression at 2 months postoperatively. The patients that did not have revision surgeries included 2 with prominent implants both found at 18 months postop, 2 with progressive deformity/PJK at 18 months average (14-22), and 2 had loss of fixation at 6 months (0-12). Conclusion: Pediatric patients with severe spinal deformity are high risk for revision surgeries at 12% rate within 2 years. The average time for revision surgery was 19 months postoperatively. These patients require close follow-up and will require continued follow-up after 2 years.

P337 - Rod Fracture in Adult Spinal Deformity Surgery Fused to the Sacrum: Prevalence, Risk Factors and Impact on Health Related Quality of Life in 526 Patients

Thamrong Lertudomphonwanit¹, Michael Kelly², Keith Bridwell², Lawrence Lenke³, Steve McAnany², Prachya Punyarat⁴, Jacob Buchowski², Bryan Timothy², Lukas Zebala², Brenda Sides², Karen May⁵, Munish Gupta²

¹Department of Orthopaedic Surgery, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok - Thailand ²Department of Orthopaedic Surgery, Washington University School of Medicine, St. Louis - United States ³Department of Orthopedic Surgery, Columbia University Hospital, New York, NY - United States

⁴Department of Surgery, Faculty of Medicine, Thammasat University, Pathumthani - Thailand ⁵Division of Biostatistics, Washington University School of Medicine, St. Louis, MO - United States

Introduction: There is limited data documenting the incidence of rod fracture (RF) following posterior spinal fusion to the sacrum in the treatment of adult spinal deformity (ASD). Our study evaluated the incidence of and risk factors for RF and determined outcomes changes associated with RF after ASD surgery. Material and Methods: A retrospective single-center analysis of ASD patients (age > 18 years) undergoing ≥ 5 vertebrae posterior fusion to the sacrum from 2004 to 2014 was performed. Patients were included if they demonstrated RF occurrence or did not develop RF with a minimum 2-year follow-up. We analyzed baseline demographic, radiographic, clinical outcomes, and operative data. We identified risk factors for RF using separate Cox proportional hazard models based on rod material and diameter. Results: Five hundred twenty-six patients out of 657 patients were included. RF occurred in ninety-seven patients (18.4%). RF occurred within three years in 51 patients (52.6%), between three and five years in 23 patients (23.7%), between five and 10 years in 22 patients (22.7%) and beyond 10 years in one patient (1%). Forty (41.2%) of 97 patients with RF required revision surgery. Risk factors for RF from multivariable model included preoperative sagittal vertical axis (hazard ratio (HR), 1.07 (95% confidence interval [95%CI], 1.02 to 1.14) per 1-cm increase), preoperative thoracolumbar kyphosis (HR, 1.02 [95%CI, 1.01 to 1.04] per 1-degree increase) and number of levels fused for patients received rhBMP-2 < 12 mg per level fused (HR, 1.48 [95%CI, 1.20 to 1.82] per 1-level increase). CoCr 5.5 mm rod diameter and stainless steel 6.35 mm rod diameter models also demonstrated the same risk factors as shown in CoCr5.5 model with additionally included CoCr 5.5 mm rod (HR, 8.49 [95%CI, 4.26 to 16.89] compared to stainless steel 6.35 mm rod). The RF group had less overall improvement in Scoliosis Research Society (SRS) satisfaction (p = 0.007) and SRS self-image domain (p = 0.01). Conclusion: The incidence of RF after index procedure was 18.4% but only 41% of the patients with RF required revision surgery. Greater preoperative sagittal vertical axis, greater preoperative thoracolumbar kyphosis, increased number of vertebrae fused for patients received rhBMP-2 < 12 mg per level fused, and CoCr 5.5 mm rod were associated with RF risk. Less improvement in patient-satisfaction and self-image was noted in the RF group. This study emphasizes that long term follow-up time, up to ten years, is needed to detect RF following ASD surgical procedures.

P338 - Effect of Obesity on the duration of Surgery, Post-Operative Complications, Need of Blood Transfusion and Total Length of Stay in the Hospital in Patients with Grade II and III Spondylolisthesis

Waleed Awwad¹, Khalid Binown Binown¹, Bdulrahman Alkadhaib¹, Nawaf Modahi¹, Saud Alfayez¹, Omar Alsultan¹

¹King Saud University Medical City, Riyadh - Saudi Arabia

Introduction: Objectives: to assess the differences between obese and non-obese patients in terms of the duration of surgery, need of blood transfusion, post-operative complications and length of hospital stay. Material and Methods: Methods: the charts of patients with spondylolisthesis who underwent transforaminal lumbar interbody fusion (TLIF) at our academic tertiary hospital from January 2013 to July 2016 were reviewed retrospectively. The inclusion criteria involved patients with grade II & III degenerative spondylolisthesis who were admitted electively for TLIF. Patients who underwent previous spine surgery, had relatively decreased hemoglobin level or managed surgically by different spine surgeons were excluded. Univariate and multivariate logistic regression analyses were conducted to evaluate the impact of obesity, among other risk factors, on the duration of surgery, post-operative complications, need of blood transfusion and total length of stay in the hospital. P-values less than 0.05 were considered significant. Results: Sixty seven patients were included of whom 55.1% were obese. The encountered complications were wound infection and deep venous thrombosis in 10.1% and 4.3%, respectively. Approximately 14.5% of the patients had suboptimal wound healing. None of the patients developed pulmonary embolism or deep infection. There were no significant differences between obese and non-obese patients. The duration of surgery was the only dependent variable that showed significant increase in the odds ratio among obese patients; however, upon multivariate logistic regression, the increase in odds ratio was not significant Conclusion: Obesity is not associated with higher rates of post-operative complications or higher hospital length of stay; however, the duration of surgery is significantly longer when operating on obese patients based on the results of the univariate logistic regression analysis.

P339 - Outcomes Revision Surgery after Instrumental Fusion of the Spine with Degenerative Lumbar Spine Disease

Alexey Evsyukov¹, Roman Khalepa¹

¹Federal Neurosurgical Center, Novosibirsk - Russian Federation

Introduction: The results of a repeat operation as a rule, are less good than in the first operation. The aim this research is to study the outcomes of revision surgical treatment of patients who had been operated on the degenerative lumbar spine disease with the instrumental lumbar spine fusion. Materials and Methods: Were analyzed the results of revision surgical treatment of 96 patients who had been operated on degenerative disease with use instrumental lumbar spine fusion. All patients 36 (37.5%) men and 60 women (62.5%). The average age is 53.8 ± 13.3. In 5 (5.2%) patients a surgical procedure was performed in our clinic. Patients underwent MRI, MSCT, X-ray of the spine with an assessment of the stability of segments, balance of the spine. Functional activity and quality of life assessment were determined by the Oswestry index before surgery and at 6 and 12 months after operation. The outcomes of treatment were assessed on the MacNab scale. Results: Patients are divided into two groups - depending on the reason of surgical treatment the failed back surgery (43 patients) and the advanced segment degeneration (53 patients). Of the 43 patients in group one 30 patients had nonunion after different lumbar fusion operations. In total, 110 surgical interventions were performed in two groups, 60 operations in 1 group and 50 operations in the second group. 62 (56.4%) patients were performed posterior surgical treatment, 25 (22.7%) patients were performed anterior lumbar interbody fusion and 23 (20.9%) were performed anterior and posterior surgical treatment. The frequency of major complications in the first group was 23 (38%), which is significantly higher (p = 0.026) than in the second 12 (24%) complications. The outcomes of the interventions was tracked during 1 year. In both groups, positive dynamics in VAS and ODI was noted: 1 group before operation 6.7 / 64.5 after 3.9 / 35.1, p < 0.005, second group before surgery 5.3 / 57.4 after 2.1 / 28.1, p < 0.005. Good clinical outcomes of differential treatment were obtained in 74.2% of patients, in the first group, the results are significantly worse than p = 0.03. Conclusions: 1. The adjacent segment degeneration is the main cause of revision surgical treatment (55.2% of patients). 2. Pseudoarthrosis is the most common cause of surgical treatment of the spine segment which had been operated, which was detected in 30 (69.8%) patients. 3. The results of surgical intervention are significantly worse (p = 0.03) after surgical treatment of pathology of the operated level than after the treatment adjacent segment degeneration.

P341 - The Surgical Learning Curve of C1-C2 Stand Alone Posterior Trans-Articular Screw Fixation Technique: Progress of a Single Surgeon, Complications and its Effect on the Outcome

Tarun Dusad¹, Vishal Kundnani¹, Ankit Patel¹, Mahendra Singh¹, Sameer Ruparel¹, Gaurav Mehta¹, Shumayou Dutta¹

¹Department of Spine Surgery, Bombay Hospital & Medical Research Centre, Mumbai - India

Introduction: Proximity of vital structures like vertebral artery, spinal cord makes Trans-articular fixation procedure technically very demanding. Despite the excellent outcomes, complications associated with this technique like vertebral artery injury (VAI) can be catastrophic. It is of paramount importance to be aware of risks associated with the procedure performed earlier in surgeon’s carrier and at what points they are expected to be competent. Performing new surgical procedure without understanding its learning curve may result into repeated and unnecessary errors. No study have analysed learning curve and single surgeon’s progress in transarticular screw fixation before. The objective of this case series was to define learning curve of C1-C2 stand alone posterior transarticular screw (TAS) fixation technique and its effect on postoperative outcomes. Material and Methods: Patients who underwent C1-C2 TAS by single fellowship trained spine surgeon in single institute were identified from prospectively maintained database and divided into early 30, middle 30 and late 36 consecutive cohort. Patient demographics, intra-operative parameters, pre and post-operative VAS, ODI, mJOA, ADI(Anterior Atlanta-Dens interval), SAC(Space available for Cord) and post-operative fusion status were noted and compared between 3 cohorts. Multivariate regression analysis was done to analyze effect of chronology of C1-C2 stand alone TAS procedure on above mentioned parameters. Learning curve was assessed on basis of negative exponential curve fit regression analysis. Results: There was steady decrease in both mean operation time and estimated blood loss from initial to recent cohort. Hospital stay also reduced significantly. There was no significant difference in change in VAS, ODI, mJOA, SAC, ADI at any point between cohorts. The interspinous fusion rate was noted significantly higher in recent cohort. Complications occurred in 7 patients (7.29%), most frequent was VAI (3 cases i.e. 3.12%; 2 in initial & 1 in recent cohort). In two of them, it occurred at the time of drilling the second screw path, thus it was first controlled with tamponade and then screw was placed. In one case, we had to avoid the screw insertion on the bleeding side, and inter laminar wire with one trans-articular screw fixation was done. None of them showed any abnormality on CT angiogram later. 2 Patients (initial cohort) had screw malpositioning without any clinical consequences. 2 patients from middle cohort had dural tear which was intra-operatively managed without any consequence in the post-operative period. Number of complications were least in recent cohort but without any statistically significant difference. On negative exponential regression analysis, 50% of improvement in surgical time was seen at case 26, and 90% learning milestone was achieved at case 78. Conclusion: Trans-articular screw fixation technique is one of the most effective option for C1-C2 arthrodesis. 50% of improvement was predicted after 25 cases and 90% after 78 cases. The results showing low complication rate suggest that it is possible to perform C1-C2 TAS early in the career of a spine surgeon without placing the patient at an increased risk for complications.

P342 - Unplanned Return to Operation Room (Or) Following Growing Spinal Constructs in Early Onset Scoliosis

Anil Solanki¹, Aditya Banta², Saumyajit Basu², Amitava Biswas²

¹Department of Spine surgery, Park Clinic, Kolkata - India ²Department of Neuroscience, Park Clinic, Kolkata - India

Introduction: Growing spinal constructs are routinely used for treatment of early onset scoliosis (EOS) and are followed by repeated planned expansion procedures. Studies have reported variable rate of complications following these surgeries – out of which many complications requires unplanned return to operation rom (OR) which demands extra resources. The purpose of this study is to evaluate the incidence and risk factors associated with the same. Material and Methods: Medical records of 12 patients of EOS operated by single surgeon using various types of growing spinal implants (growing rod, VEPTR and hybrid type VEPTR) were evaluated for complications requiring unplanned surgeries. Complication included were pullout/loosening of screws/anchors, breakage of rod/screws, infection and wound healing problems, neurological deficit, etc. Data was analysed to find out rate of unplanned surgeries and relation with age at index surgery, type of implant, diagnosis, reason for unplanned surgery and management. Results: The study included 9 congenital, 2 syndromic and 1 neuromuscular scoliosis that were operated from 2011 to 2017. Mean age at index surgery was 5.5 years (range 2 years to 8 years) and average period of follow up was 34.33 months. There were 7 growing rod, 4 VEPTR and 1 hybrid VEPTR constructs included in the study. 8 out of 12 patients had one or more unplanned surgeries till end of follow up (66.67%). Out of total 72 surgeries following index procedure (Growing construct implantation) 34 were unplanned surgeries (47.22%), including 26 surgeries for implant related complications (14 rod/screw breakage, 12 screw/anchor pullout), 6 for wound healing problems (5 infections and 1 wound dehiscence) and 2 for neurological deficits (delayed). Surgical management of complications included -- 22 implant revisions, 8 implant removal, 3 debridement (retaining implant) and one plastic surgery procedure for coverage. Looking at initial diagnosis, there were 20 out of 52 surgeries in congenital scoliosis (9 patients), 7 out of 12 in syndromic (2 patients) and 7 out of 8 surgeries in neuromuscular scoliosis (1 patient) were unplanned. As per implant type, there were 26 out of 49 surgeries (53.06%) following growing rod and 8 out of 23 surgeries (34.78%) following VEPTR (which also include hybrid VEPTR) were unplanned (p = 0.15).When age of implantation of growing construct was < 5 years, 20 out of 35 (57.14%) surgeries were unplanned and with age > 5 years, there were 14 out of 37 (37.84%) unplanned procedures (p = 0.10). Conclusion: Growing spinal constructs in EOS requires frequent revisit to operation room which includes significant number of unplanned visits regardless of implant type- which should be well understood by surgeon, patient and care-takers. Unplanned return to Operative room is mostly due to rod/ screw breakage or pullout but also can be due to neurodeficit or wound healing problems/infection. Management of complications frequently requires revision of constructs or implant removal and/or debridement. Unplanned reoperations are relatively more in syndromic and neuro-muscular cases than congenital and especially higher if age at initial implantation is less than 5 years.

P343 - Latin American Spinal Surgeons’ Perception About Complications

Asdrubal Falavigna¹, Jeferson Dedea²

¹University of Caxias do Sul - Brazil ²Laboratory of Clinical Studies and Basic Models on Spinal Cord Pathologies, University os Caxias do Sul - Brazil

Introduction: By 2060, it is estimated that approximately 23% of the population over 65 years of age will present with some degree of spinal deformity. This rise in the number of cases will increase the demand for corrective surgery and consequently the complications. These postoperative complications of spine surgery are not well defined in the literature. In this context, the cultural diversity present in Latin America (LA) can determine how each professional perceives these complications. The objective of the study is to analyze the perception of spine surgeons regarding complications in the postoperative period. Material and Methods: A questionnaire was sent to spine surgeons who were members of AOSpine Latin America, containing the following variables: specialty, years of practice, the annual number of surgeries with and without instrumentation, and eleven scenarios of surgical cases with different degrees of complications. The professionals were asked about their perception regarding the complications, classifying them as major, minor or without complication. Statistical analysis of the data was performed using the IBM SPSS® 22.0 program, and presented a value of p < 0.05 Results: Of the 708 questionnaires answered, orthopedic surgeons represent about 58.2% (n = 412) and neurosurgeons 41.8% (n = 296). The most experienced professionals ( > 10 years) corresponded to 45.6% (n = 323) of the sample. The countries with more than 50 respondents were included in the study and the results were compared between them. The countries analyzed were Brazil (31.5%), Mexico (17.5%), Argentina (14.4%), Colombia (8.0%) and Venezuela (7.6%). There was a consensus among surgeons that wound infection (99.7%), blood loss (86.6%), deep venous thrombosis (93.2%) and screw positioning (93.0%) were considered major complications. However, there is no agreement on the complications of dysphagia (69.2%) and movement limitation (22.6%). Among LA respondent countries, there is a difference in how surgeons perceive complications. In Venezuela, 59% of surgeons believe that movement limitation is not a complication, and the average in LA is 75.2%. Deep wound infection was perceived by Colombia spine surgeons as a minor complication in 16% of surgeons, compared to 34.2% from LA surgeons. The North American (NA) spine surgeons believe that dysphagia is a minor complication in 58% of cases, which increases the percentage in LA spine surgeon to 76.8%. Intraoperative blood loss was seen as a serious complication by 25% of NA surgeons and 39.2% from LA. There was a consensus between the countries of LA and NA that classified urinary tract infection (81.4% vs 80%), inflammation (86.2% vs 80%) and screw malpositioning (66.6% vs 62%) as minor complications. Conclusion: The perception of complications by spine surgeons depends on regional experience. A significant agreement was found in the perception of the presence and types of complications in most of the scenarios.

P344 - Intrathecal Morphine Use in Patients Undergoing Spine Surgery Necessitating Transfer to the Intensive Care Unit due to Postoperative Complications

Ryder Reed¹, Robin Carlson², Michelle George², John McClellan²

¹Nebraska Spine Hospital, Omaha, United States

Introduction: Intrathecal morphine in major spine surgery has proven an effective means of controlling pain during the first post-operative day. However, complications caused by narcotics remain a primary concern for clinicians. Of specific concern when administering morphine intrathecally is the potential for both immediate and late-onset respiratory depression. For highly-specialized centers such as a spine hospital, postoperative complications may necessitate transfer to an intensive care unit to manage the patient. Indeed, the transfer leads to a lower quality of care and poorer patient outcomes. A closer review of adverse events following intrathecal morphine administration may provide insight into the precipitating factors and ultimately help determine instances in which intrathecal morphine should be withheld. This study aims to characterize instances of postoperative complications necessitating transfer to the ICU following intrathecal morphine administration during spine surgery. Materials and Methods: A retrospective case study of the electronic medical records (EMRs) of 37 patients were inspected individually by an independent reviewer to extract the required data, including length of stay, intrathecal use and dosage, demographic factors such as age, BMI, and gender, American Society of Anesthesiologists (ASA) Physical Status Classification score, and complications. Data were compiled and grouped to describe features shared among discharged patients who received intrathecal morphine during their operation. Of the 2456 patients who underwent inpatient spine surgery between 2015 and 2017, 37 were transferred to the ICU and ranged in age from 32 – 83, with 16 being male and 21 females. Results: Of the 37 patients transferred to the ICU, 9 patients (24%) received intrathecal morphine. The average age of this subset was 60 with an average BMI of 31. Doses of morphine ranged from 300 µg to 1 mg, with 400 µg being the most frequently used dose. seven of the nine patients had an ASA Physical Status Classification score of 3 and the remaining two had an ASA score of 4. A further analysis of those 9 patients revealed that 5 were discharged due to cardiovascular complications and 4 were discharged due to respiratory failure. All the transfers due to respiratory failure occurred within 12 hours of the start of surgery. Additionally, 3 of these 4 patients had a history of respiratory disease such as asthma (2), obstructive sleep apnea (2), and COPD (1). The average length of stay prior to transfer due to cardiac complications was 24 hours and every patient had some history of cardiovascular disease, such as hypertension (4), hyperlipidemia (3), arrhythmia (3), myocardial infarction (1), and stroke (1). Conclusions: Here we have described features of patients transferred from a specialty spine hospital to the ICU following spine surgery in which they received intrathecal morphine. These results would indicate that more care should be taken in weighing the analgesic effects of intrathecal morphine with the complications it may precipitate, particularly in morbid patients as indicated by their ASA score. While there is little doubt that effective pain management is good for patient satisfaction, the safety of certain means should be questioned in certain instances.

P345 - Efficacy of Prochlorperazine Maleate Preoperative Medication for Postoperative Nausea and Vomiting (Ponv) in Spinal Surgery

Yushi Hoshino¹, Atushi Sato¹, Kazunari Tomita¹, Yoshifumi Kudo², HIroshi Maruyama², Toshiyuki Shirahata², Tomoaki Toyone², Katunori Inagaki²

¹Dept. of Orthopedic Surgery, Showa University, Koto Toyosu Hospital, Tokyo - Japan ²Dept. of Orthopedic Surgery, Showa University, School of Medicine, Tokyo - Japan

Introduction: The mean frequency of postoperative nausea and vomiting (PONV) has been reported to be 30%. PONV causes discomfort to patients, prevents early ambulation, and thus, decreases patient satisfaction. Here, we investigated whether preoperative oral administration of prochlorperazine maleate (Novamin) prevents PONV after spinal surgery. Methods: In this retrospective study, we included 195 patients who underwent spinal surgery under general anesthesia at our hospital between April 2014 and September 2016. The patients were divided into two groups: 87 patients not receiving prochlorperazine (untreated group: April 2014 to May 2015) and 108 patients receiving prochlorperazine (treated group: June 2015 to September 2016). Patients in the treated group received oral administration of prochlorperazine at 6:00 am before surgery or at bedtime after surgery on the day of surgery. We compared the incidence of PONV, the number of patients receiving an intravenous injection of metoclopramide (Primperan), and its dosage between the two groups. In addition, we assessed the patient sex, age, operative time, Apfel score, and use of intravenous patient controlled analgesia (IV-PCA). Results: The incidence of PONV was 35% in the untreated group and 25% in the treated group. Although not statistically significant, the incidence of PONV was lower in the treated group. The number of intravenous metoclopramide injections per patient with PONV was 1.41 in the untreated group and 1.11 in the treated group, which was not significantly different. Although the incidence of PONV was significantly high in patients with an operative time of 120 min, no significant differences were observed in Apfel score or sex. Among patients who received IV-PCA combined with droperidol, the incidence of PONV in the untreated group, 38%, was significantly lower than that in the treated group, 20%. Discussion: The incidence of PONV in patients undergoing spinal surgery is approximately 35%, which is not a low rate for a surgical complication. Prochlorperazine has a long half-life, and thus, oral administration of prochlorperazine before surgery may prevent PONV. Oral administration of prochlorperazine showed a decrease in the incidence of PONV; however, this decrease was not statistically significant. Moreover, prochlorperazine was effective in patients using postoperative IV-PCA, which suggested an alleviation of PONV, which is an adverse reaction to opioids. Our results indicate that preoperative administration of prochlorperazine may prevent PONV associated with spinal surgery. Further, when IV-PCA is used for postoperative pain control, preoperative administration of prochlorperazine is effective.

Summary: In spinal surgery, preoperative administration of prochlorperazine maleate may prevent postoperative nausea and vomiting.

P346 - Difference in the Changings of Blood Coagulation Fibrinolysis Markers Before and after Spinal Surgery in Adolescent and Elderly Patients

Hideaki Watanabe¹, Hirokazu Inoue², Ryo Sugawara¹, Ichiro Kikkawa¹, Kastushi Takeshita²

¹Department of Pediatric Orthopedic Surgery, Jichi Children’s Medical Center, Shimotsuke - Japan ²Department of Orthopedic Surgery, Shimotsuke - Japan

Introduction: The incidence of venous thromboembolism (VTE) after pediatric spinal surgery (0.09%-0.30%) is lower than that after adult spinal surgery (0.3%-31.0%). To investigate the development of postoperative VTE, we evaluated changes in blood coagulation-fibrinolysis markers after spinal surgery in adolescent and elderly patients. Material and Methods: In this retrospective study, we enrolled 27 adolescent patients who underwent posterior fusion for adolescent idiopathic scoliosis (AIS) and 31 elderly patients who underwent laminectomy for lumbar spinal stenosis (LSCS). No patients had risk factors for VTE. Blood samples were taken preoperatively and at 1, 3, and 7 days postoperatively. D-dimer, soluble fibrin monomer complex (SFMC), and plasminogen activator inhibitor type 1 (PAI-1) levels were measured. Results: Significantly increased D-dimer levels were observed on postoperative days 1, 3, and 7 in both groups (p = 0.01). Increased SFMC levels were observed on postoperative days 1 and 3 in the AIS group and on day 1 in the LSCS group (p = 0.01). Increased PAI-1 levels were observed on postoperative day 7 in the AIS group and on days 1, 3, and 7 in the LSCS group (p = 0.01). Conclusion: The persistent increase in postoperative PAI-1 in elderly patients may be associated with the development of postoperative VTE.

P347 - Complications in Adult Spine Deformity Surgery: A Systematic Review of Literature

Sigurd Berven¹, Charles Ledonio², David Polly³

¹Chief Spine Service, Department of Orthopaedic Surgery, UCSF, San Francisco - United States ²Innovative Surgical Designs, Wayne - United States ³Chief Spine Service, Professor, Department of Orthopaedic Surgery, University of Minnesota, Minneapolis - United States

Introduction: There has been an exponential increase in the number of spine surgeries over the past 2 decades as a result of a growing elderly population and advances in surgical innovations. Surgical management of adult spinal deformity (ASD) are technically challenging and are associated with high rates of complications. With advances in technology and knowledge more surgeons are operating on increasingly challenging cases. As surgeons become more experienced with ASD surgery they are developing a better understanding of the patient-specific limitations to surgery. Thoughtful consideration of the complications related to adult spine deformity surgery is essential. Complications lead to longer hospital stay, higher mortality rate, higher readmission rate, and higher overall cost of treatment all of which lead to diminished efficacy and cost-effectiveness of surgical treatment. Thus there has been an interest in creating a meaningful and comprehensive reporting of complications. Material and Methods: An electronic keyword search using PubMed/Medline and EMBASE was conducted with a professional librarian with expertise on literature reviews from the University of Minnesota’s Biomedical Library. The citations were initially screened objectively using the following guidelines: Commentaries, letters to the editor, non English and review articles were excluded. Poorly designed studies which did not clearly state the outcomes for the device were excluded.

After the initial screening the criteria below was used to include or exclude the full text articles.

Inclusion criteria

Outcome studies with complications reported

100 patients

1-2 year follow-up

Complications mentioned in the series

Adults Results: Ailon et al defined Spinal deformity can as an abnormality in alignment, formation, or curvature of 1 or more portions of the spine. They describe Adult spinal deformity (ASD) as a wide range of conditions that result in abnormal spinal alignment and may result in pain, disability, neurological impairment, and/or loss of function. The search yielded 1244 articles of which only 274 were initially excluded leaving 970 abstracts reviewed. Of these 456 full text articles met inclusion criteria and reviewed in detail. Of these only 20 met the inclusion criteria. Complications were classified as major or minor; per organ system; 30-90 day readmission rates; and per incidence. Complications are an important concern in surgical treatment of ASD and a high incidence of surgical complications has been reported. The percentage of major complications was 5.5-7.3% and for minor complications was 5-6.3%. Infection were common and range from 1-11%. However, the data quality, procedures, diagnosis and collection method of complications varied greatly. Therefore, pool ability of data was not possible. Overall, the rate of complications was generally high - 22%. Conclusion: There is tremendous variability in reporting of complications for ASD surgery. There is an urgent need to establish a standard to systemically observe and record the complications related to different surgical procedures. Critical analysis of past complications can hopefully lead to strategies to avoid future complications and to improve patient outcome.

Trauma - Cervical

P348 - Analysis of Spinal Motion and Dural Sac Compression in the Unstable Upper Cervical Spine During the Application of a Cervical Collar

Sven Vetter¹, Shiyao Liao¹, Niko R. E. Schneider², Paul A. Grützner¹, Erik Popp², Stefan Matschke¹, Michael Kreinest¹

¹BG Trauma Center Ludwigshafen, Department of Trauma Surgery, Ludwigshafen - Germany ²Heidelberg University Hospital, Department of Anesthesiology, Heidelberg - Germany

Introduction: Instable conditions of the upper cervical spine such as atlanto-occipital dislocation (AOD) or atlanto-axial instability (AAI) are severe injuries with a high risk of tetraplegia or death. Immobilization of the cervical spine by a cervical collar to protect the patient from secondary damage is a standard procedure in trauma patients. If the application of a cervical collar to a patient with an unstable upper cervical spine may cause secondary injury to the spinal cord based on semental motion and compression of the spinal cord is unknown. The aim of the current study is (i) to analyze compression on the dural sac and (ii) to determine spinal motion during the application of a cervical collar in case of an unstable upper cervical spine Material and Methods: In six fresh cadavers each, ligamental AOD as well as ligamental AOD combined with ligamental AAI was simulated. Real-time changes of the dural sac’s width was measured during the application of a cervical collar (Stifneck Select, Laerdal Medical, Puchheim, Germany) by video fluoroscopy (Veradius C-Arm, Philips, Netherlands) and myelography (Optiray, 300 mg/ml, Mallinckrodt, Germany). Furthermore, segmental angulation and distraction in the upper cervical spine was analyzed by fluoroscopy data. Overall 3D spinal motion were measured by a motion tracking system (Xsens Technologies, Enschede, Netherlands). Sample size calculation and statistical analysis was performed with SPSS (IBM, USA). Results: Mean dural sac’s width was significantly decreased about 1.1 mm (range: 0.7 to 1.0 mm) in case of AOD and about 1.2 mm (range: 0.6 to 1.6 mm) in case of combined AOD and AAI. A significant (p = 0.028) increased angulation of 4.9° (range: 3.8 to 7.0°) was measured at C0/C1 segment in case of AOD. C1/C2 level was distracted 0.91 mm (range: 0.64 to 1.75 mm) during the application of a cervical collar in case of stable upper cervical spine. No significant changes have been seen towards distraction in case of AOD nor in case of combined AOD and AAI. Moreover, immense three-dimensional movement up to 22.9° of cervical spine flexion was documented during the procedure of applying a cervical collar. Conclusion: Mean dural sac’s width was significantly decreased about 1.1 mm (range: 0.7 to 1.0 mm) in case of AOD and about 1.2 mm (range: 0.6 to 1.6 mm) in case of combined AOD and AAI. A significant (p = 0.028) increased angulation of 4.9° (range: 3.8 to 7.0°) was measured at C0/C1 segment in case of AOD. C1/C2 level was distracted 0.91 mm (range: 0.64 to 1.75 mm) during the application of a cervical collar in case of stable upper cervical spine. No significant changes have been seen towards distraction in case of AOD nor in case of combined AOD and AAI. Moreover, immense three-dimensional movement up to 22.9° of cervical spine flexion was documented during the procedure of applying a cervical collar.

References

1. Hindman BJ et al. (2015) Anesthesiology 123: 1042

2. Eismont FJ et al. (1984) Spine 9: 663

P349 - Cervical Spine Immobilization and Clearance Following Blunt Trauma: Practices at a Tertiary Care Trauma Center in a Developing Country

Badar Ujjan¹

¹Department of Neurosurgery the Aga Khan Hospital, Karachi - Pakistan

Background: An overzealous and indiscriminate use of Philadelphia collar was observed in our Emergency Department. Many patients fulfilling the criteria of clinical clearance receive rigid collar immobilization that sometimes stays for days despite a lack of clear indication. To confirm these observations and to improve our practice of cervical spine immobilization we planned a prospective observational study in which we studied the practices of cervical spine immobilization in trauma victims reporting at hour hospital.

Method: This was a prospective observational study conducted at The Aga Khan University Hospital Karachi Pakistan from 2nd December 2015 to 18th February 2016. We included all the patients irrespective of mechanism, gender, injury severity who presented in Emergency Room with a history of trauma and received cervical collar. Criteria for application and cervical clearance were recorded. We analyzed the data using SPSS v 20 IBM. Mean ± standard deviation was calculated for continuous data with normal distribution. Result: A total of 94 patients were included in the study. Cervical injury was present in 5 out of the 94 patients, provided cervical collar in ER. 43 patients had at least one of the high-risk factors mentioned in the Canadian C-spine Rule. In the remaining, 48 patients had at least one of the low-risk factors mentioned in the Canadian C-Spine rule. According to the Canadian C spine rule only 54 patients should have received. The use of Xrays was also noticed to be indiscriminate with about 85% patients undergoing Xrays which were mostly inadequate. Conclusion: Cervical collar immobilization is overused in the setting of emergency room. Strictly following the Canadian C rule can significantly limit the number of cervical collars used. Countries with limited resources must try to practice cost effective medicine.

Keywords: cervical collar, cervical trauma, cervical immobilization

P350 - Outcomes of Unstable Subaxial Cervical Spine Fractures Managed by Postero-Anterior Stabilization and Fusion

Mithun Jakkan¹, Rishi Dwivedi², Charanjit Singh Dhillon²

¹Department of Spine Surgery, Solapur - India ²Department of Spine Surgery, Chennai - India

Introduction: Unstable subaxial cervical spine injuries that often involve disruption of anterior column as well as posterior tension band osteo-ligamentous complex. Such injuries need immediate surgical intervention. Different methods of reduction and surgical approaches have been published in literature with lack of consensus on uniform or standardized method. Controversy still exists regarding stabilization of unstable cervical fractures by anterior or posterior alone or combined approaches. Method: Total 24 cases of post-traumatic unstable subaxial cervical spine injuries were retrospectively evaluated with their pre-operative clinical details, X-ray, CT and MRI of cervical spine for fracture classification according to the mechanism of injury with status of disc herniation and posterior tension band disruption. All patients were managed by immediate reduction, posterior and anterior stabilization and fusion in a single session of anesthesia. Data of all patients were analyzed with respect to preoperative and postoperative neurological status by ASIA(American spinal injury association) grading, Visual analogue scale, bony fusion, implant failure at 1, 3 6 and 12 months. Data were analyzed using paired t-test. Results: All cases had solid fusion at the desired level with considerable neurological improvement by the follow-up of one year. Conclusion: In unstable cervical injuries, stabilization of disrupted posterior tension band increases the stability to anterior plating and fusion. This method of immediate reduction and circumferential stabilization is rapid, safe, effective and has low complications.

P351 - Blunt Trauma to the Cervical Spine with Brown-Sequard Syndrome Presenting as a Cerebrovascular Stroke

Igor Movrin¹, Tomi Kunej¹

¹Department of traumatology, University Medical Centre, Maribor - Slovenia

Introduction: We present a case of incomplete spinal cord injury after C6 lamina fracture that initially presented as a suspected cerebrovascular stroke (CVS). Material and Methods: An 80-year old female patient presented to the ED as a candidate for thrombolysis after a suspected CVS. CT and CTA of the head and neck showed no ischaemic lesions in the brain, instead a fracture of the posterior part of the body and the right lamina of C6 with suspected dissection of the right vertebral artery was discovered. Detailed neurologic exam showed ipsilateral hemiparesis and contralateral change in pain and temperature perception – Brown-Sequard syndrome. Emergency MRI of the head and cervical spine showed oedema of the spinal cord at the C6 level with a suspected rupture of the anterior longitudinal ligament. Results: At the time of diagnosis methylprednisolone was given. Emergency surgery with laminectomy, posterior fixation, anterior discectomy, partial corpectomy and fusion with a cortico-cancellous graft and locking plate was performed 5 hours after presentation. Postoperatively marked improvement in neurological status was seen, with nearly normal motor function of the lower extremity, some muscle weakness in the right arm remained. Pain and temperature perception deficits did not improve. 35 days after surgery the patient was mostly independent in day-to-day activities and was transferred to a non-acute care institution. Conclusion: Blunt trauma to the cervical spine with hemiparesis can mimic the symptoms of a CVS. We suggest that a cervical spine CT and/or MRI should be performed in cases of ambiguous imaging findings. The best management for such injuries is spinal cord decompression with stabilisation as necessary.

P352 - Motion Preserving Fixation Procedure for the Treatment of Hangman’s Fracture

Gohsuke Hattori¹, Hisaaki Uchikado², Motohiro Morioka¹

¹Department of Neurosurgery, Kurume University School of Medicine, Kurume - Japan ²Uchikado Neuro-spine Clinic, Fukuoka - Japan

Introduction: Opinions have varied regarding the optimal treatment of an unstable hangman’s fracture. C2 pedicle screw instrumentation is a biomechanically strong fixation witch although done through a simple posterior approach. The purpose of this study is to determine the effectiveness of C2 pedicle screw fixation on Hangman’s fracture management. Methods: This prospective study included 6 consecutive patients with displaced type II or IIA traumatic spondylolisthesis of the axis. There were three males and three females with mean age of 58 years at surgery. The cause of injury was a road traffic accident in 3 patients and a fall from height in 3 patients. All patients had a single stage reduction and direct transpedicular screw fixation through the C2 pedicles. Two patients required additional fixation with the C3 lateral mass screw. During follow-up, clinical evaluation and plain X-rays were performed at each visit; at 3, 6, and 12-month follow-up, additional dynamic lateral flexion/extension views and a CT scan were performed. Results: Mean follow-up period was 85 months (range of 53-100 months). At final follow-up, all patients were asymptomatic and regained a good functional outcome with no limitation of range of motion; all the patients showed solid union with no implant failure. There were no neurological complications. At 6-month follow-up, CT evaluation showed fusion in all patients and an adequate position of 12 screws. Conclusions: Transpedicular screw fixation through the C2 pedicles is a safe and effective method in the treating type II traumatic spondylolisthesis of the axis. It produces good clinical and radiological results. Adequate reduction was achieved and motion segments were preserved with its use.

P353 - A Chronic Odontoid Fracture Diagnosed and Treated 12 Years after Cervical Trauma

Jonathan Samuel Morgado Vázquez¹, Jorge Luis Olivares Peña¹, Carlos Raul Rangel Morales¹, Jorge Arturo Santos Franco¹

¹Department of Neurosurgery, Mexican National Medical Center “La Raza” IMSS, Mexico City - Mexico

Introduction: Injury to the cervical spine due to trauma is responsible for 6,000 deaths and 5000 new cases of quadriplegia in the United States of America every year (1). Odontoid fractures represent 9% to 15% of all fractures in cervical trauma (2,3). The most frequent odontoid fractures are type II according to the classification of Anderson and D’Alonso which represent a fracture at the base of the odontoid process. Less than 10% of fractures are accompanied by neurological deficit (2). It has been reported that 4 to 30% of fractures are not diagnosed (4). This abstract presents the case of a chronic fracture of the Odontoid process type II discovered 12 years after falling from three meters in height, which developed pseudoarthrosis and had transient episodes of neurological deficit prior to its diagnosis and treatment. Material and Methods: A 34-year-old male with a history of falling from three meters in height at age of 22 years treated only with NSAIDs, with transient quadriplegia (20 minutes) with total posterior recovery, after trauma he used to present transient episodes of paraplegia (15-20 minutes) 1 to 2 times per year whit physical effort like playing soccer with posterior total recovery. It is received in the emergency room after riding a roller coaster with posterior quadriplegia without recovery. A tomography was performed, observing a fracture in the base of the odontoid process, classified as a type II fracture (Anderson and ‘D’Alonso) and changes in bone density suggestive of an old fracture with features of a pseudoarthrosis process, magnetic resonance imaging showed chronic myelopathy at the level of C1-C2 confirming an old fracture. A transoral approach whit odontoidectomy and posterior occipito-cervical fixation where performed. After surgical management, the patient had recovery whit global force 4/5 at discharge 5 days after a surgical event. A literature search was conducted in the MEDLINE database through PubMed to search for articles similar to our presented clinical case. English MeSh terms were used to maximize search results. Only the filter to accept articles in English and Spanish language was used. No time limits were used. We used the following search strategy (“OdontoidProcess / abnormalities” [MeSH] OR “OdontoidProcess / injuries” [MeSH] OR “OdontoidProcess / physiology” [MeSH] OR “OdontoidProcess / physiopathology” [MeSH] OR “OdontoidProcess / surgery” [MeSH] AND “Spinal Fractures” [MeSH] AND “Chronic Disease” [MeSH]. The results showed 5 articles that fit the search criteria; three were excluded due to the language (2 in German and 1 in French) and the other one was reviewed. The study by Blacksin and Avagliano presented 3 cases of chronic odontoid fracture (5). The maximum time span between the injury and the diagnosis was 1 year in the three patients examined. The diagnostic criteria used by the authors to determine the chronicity of a fracture were also used to the images of the patient of our case, and all of them fit in the category of chronic fracture of the odontoid process. Results: After surgical management, the patient had recovery whit global force 4/5 at discharge 5 days after a surgical event. A rare case of a type II odontoid fracture with diagnosis is presented 12 years after the traumatic event with a favorable evolution after their surgical treatment. Conclusion: The correct evaluation of a patient after cervical trauma must be complete to avoid a latent risk of morbidity and mortality. Presenting this case serves as a precedent for treating injuries of a long evolution.

References

1. Davenport M, Mueller J, Belaval E, et al. Fracture, cervical spine. eMedicine Specialties, Emergency Medicine, Trauma & Orthopedics; 2008

2. Patel A, Smith HE, Radcliff K, Yadlapalli N, Vaccaro AR. Odontoid fractures with neurologic deficit have higher mortality and morbidity. Clinical Orthopaedics and Related Research. 2012;470(6):1614–1620.

3. Bohlman H. Acute fractures and dislocations of the cervical spine. Analysis of three hundred hospitalized patients and review of the literature. Journal of Bone and Joint Surgery A, vol. 61, no. 8, pp. 1119–1142, 1979. [8] B.

4. Gerrelts D, Petersen EU, Mabry J, and Petersen SR. Delayed diagnosis of cervical spine injuries. Journal of Trauma, vol. 31, no. 12, pp. 1622-1626, 1991.

5. Blacksin MF, Avagliano P. Computed tomographic and magnetic resonance imaging of chronic odontoid fractures. Spine, vol. 24, no. 2, pp. 158-162, 1999.

P354 - Post-Traumatic C7-D1 Fracture Dislocations: Technical Nuances and Surgical Outcome

Ravi Sharma¹, Shashank Kale¹, Sachin Borkar¹

¹Department of Neurosurgery AIIMS New Delhi, New Delhi - India

Introduction: Cervicothoracic (C7-D1) fracture-dislocations are rare, but an important cause of traumatic paraparesis or paraplegia especially in young adults. Only very few studies are available in the literature which describe in detail the clinico-radiological characteristics and outcome of such injuries. Objective: To perform an analysis of clinical features and radiological findings of traumatic fracture-dislocation in the region of the seventh cervical to the first thoracic vertebrae and to discuss treatment modalities and outcomes in patients managed at a level 1 apex trauma centre. Material and Methods: The present study is a prospective cum retrospective study of 41 patients with C7 to D1traumatic fracture operated over 7 years (2009-2016) at a level 1 apex trauma centre in India. Results: Mean age at presentation was 30.5 (range 5yrs - 59 yrs). 27 patients (65.8%) suffered from low velocity trauma. 30 patients (73.1%) had complete motor and sensory loss at the time of presentation. Mean preoperative Frankel score was 1.23. Most common vertebral involvement was both C7 and D1 in 20 patients, C7 alone in 18 patients, D1 alone in 3 patients. Mean duration from injury to surgery was 10 days (range 1 day - 24 days). Majority patients were approached anteriorly (80.4%). Four patients (9.8%) were operated through posterior approach. Combined anterior and posterior approach was used in 4 patients (9.8%). Mean postoperative Frankel score at discharge was 2.1. Final outcome was measured at last follow up visit. Most common complication was pulmonary infection in 15 patients (36.5%). In hospital mortality was 12.2%. Mean follow up was 4.8 years (range - 6 months to 6.5 years). Out of 41 patients 34 patients were available for follow up. Out of 34 available for follow up 20 patients (58.8%) showed improvement in motor function. Conclusion: Cervicodorsal fracture dislocation is cause of significant mortality and morbidity in young population. Anterior surgical approach is safe and effective intervention . Long term follow up indicates improvement in motor function in more than half of the patients.

P355 - Predictors of In-Hospital Mortality in Patients with Cervical Spinal Cord Injury: A Systematic Review of Current Literature

Amr Eisa¹, Sarang Sapare², Muralidharan Venkatesan², Nasir Quraishi²

¹Assiut University Hospitals, Assiut - Egypt ²The Centre for Spinal Studies and Surgery, Queen’s Medical Centre, Nottingham - United Kingdom

Introduction: Cervical spinal cord injury is a devastating consequence of high energy trauma and despite of advances in emergency care of quadriplegia patients it is associated with high in-hospital mortality. We conducted systematic review of current literature to identify the predictors of in-hospital mortality in patients with cervical spinal cord injury. Materials and Methods: Two independent reviewers conducted systematic review of English literature between period January 2000 and May 2017 for articles reporting predictors of in-hospital mortality after traumatic spinal cord injuries. Review was conducted according to PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses) guidelines using a PRISMA checklist. Inclusion criteria were studies with more than 50 adult patients (18 years or older) with traumatic spinal cord injury and reporting predictors of mortality. We included those predictors when at least two studies were available for those predictors. The method of best evidence synthesis for observational studies were used to analyse the quality of each studies and for synthesis of final evidence. Results: The search strategy resulted in 8 articles. Three studies were rated as ‘high quality’, one study as ‘moderate quality’ and four as ‘low quality’. Increasing age, higher cervical level, early surgical decompression, higher ASIA grade at presentation, ventilatory requirements and cardiovascular stability are all observed to be associated with high in-hospital mortality in this patient population. Increasing age and longer ventilatory support were consistently found to be associated with high in-hospital mortality with moderate grade of evidence. Conclusion: Whilst there is no conclusive strong evidence of the predictors for in-hospital mortality following cervical spinal cord injury, special attention should be paid to the above observed predictors. Further prospective studies are warranted in large samples that can delineate the most effective predictor or combination scheme of predictors to ultimately aid clinicians risk stratify the patients and improve the survival outcome.

P356 - National Trends in C2 Fractures and Their Treatment – An 11 Year National Inpatient Sample Study

William Ryan Spiker¹, Darrel S. Brodke¹, Nicholas Spina¹, Brandon D. Lawrence¹, Vadim Goz¹, Brook I. Martin¹

¹Department of Orthopaedics, University of Utah, Salt Lake City - United States

Introduction: Fractures of the axis (C2) account for between 9% and 18% of all cervical spine fractures. These fractures have been traditionally thought of as having a bimodal age distribution, presenting in the younger population from high-energy trauma and in the older population from low energy trauma. The spectrum of interventions range from nonoperative treatment with a cervical orthosis to operative intervention with instrumented fusion. A significant amount of controversy remains regarding nonoperative versus operative treatment of geriatric C2 fractures. Materials and Methods: We used AHRQ’s National Inpatient Database (NIS) to identifypatients having a hospital admission for C2 fracture as coded using International Classification of Disease, 9th Revision, Clinical Modification (ICD-9-CM). Patients with previous surgery, spinal cord injury, congenital anomalies, and cancer, or spine fractures at other levels were excluded. Survey-weighted generalized regressions were used to describe trends in annual operative and non-operative care, and in-hospital mortality, controlling for age, sex, race, comorbidity, income, elective admission, and year. Results: C2 fracture incidence increased from 3 per 100 000 in 2002 to 4.2 per 100 000 in 2013. Fractures in the elderly population have increased from 60% of all C2 fracture admission in 2002 to to 74% in 2013. This has resulted in a distribution of C2 fractures that peaks in the over 85 age range. Although there was an 87% increase in C2 fracture admissions from 2002 to 2013, the proportion of surgically treated patients decreased slightly from 13.5% in 2002 to 11.5% in 2013 Of the operatively treated patients, 78% were elective admissions and 22% were emergent. In the non-operative group, 95% were treated electively and only 5% were emergent. The length of hospital stays for operatively treated has decreased over time. In hospital mortality increased with age, but was significantly lower in the operative group (OR 0.483, p < -.001). Conclusions: Overall rates of C2 fractures have increased over time while the proportion of operatively treated C2 fractures have slightly decreased. This may be related to the fact that most patients treated operatively for C2 fractures today in the United States are treated in an elective setting.

P357 - Comparison of Two Temporary Fixation Techniques for the Treatment of Odontoid Fracture

Linnan Wang¹, Tao Li¹, Xi Yang¹, Lei Wang¹, Li-min Liu¹, Hao Liu¹, Yue-ming Song¹

¹West China Hospital, Chengdu - China

Introduction: To evaluate and compare the clinical and radiographic results between temporary C1-C2 pedicle screw fixation and cable-dragged reduction and cantilever beam internal fixation. Materials and Methods: Between 2010 and 2013, temporary C1-C2 pedicle screw fixation (Group P, 28 patients) and cable-dragged reduction following cantilever beam internal fixation (Group C, 33 patients) were performed on type II odontoid fracture cases. Implants were removed after fracture union. Results: All of the 61 surgeries were performed successfully with no iatrogenic neurological worsen. One patient in Group P detected intra-operative vertebral artery injury. All patients gained fracture union. Among the observed indexes, only blood loss in Group P (128.9 ± 73.9 ml) is statistically higher than in Group C (97.3 ± 54.2 ml). Conclusions: Pedicle screw fixation carries the risk of vertebral artery injury, especially in patients with high-riding vertebral artery. Cable-dragged reduction following cantilever beam internal fixation could avoid the potential risk of vertebral injury, but it prolonged the fixed segments. We thought cable-dragged reduction following cantilever beam internal fixation could be an alternative method for treating.

P358 - Results in Percutaneous Posterior Screw Fixation C1/C2 for Stabilization of Pseudarthrosis of Odontoid after Previous Ventral Screw Fixation in Unstable Odontoid Fractures Type Anderson 2 in the Elderly

Stefan Hauck¹, Jan Vastmans¹, Thomas Weiss¹, Oliver Gonschorek¹

¹Spine surgery, Murnau - Germany

Introduction: For the surgical treatment of unstable odontoid fractures in old age several several surgical procedures are possible: direct anterior screw fixation of the dens, with one or two screws at the age. This often leads to pseudarthrosis of odontoid with an unstable fracture situation. This leads to the loosening of screws in osteoporotic bone metabolism. Revision surgery as the dorsal open technique with C1/C2-screw fixation and iliac crest bone graft and cerclage is very stressful for the elderly. The dorsal percutaneous screw fixation C1/C2 can lead to healing of the odontoid fracture. After completion of the fracture healing the screw fixation can be removed. Material and Methods: In a prospective study was carried out 10 patients over 60 years with unstable pseudarthrosis of odontoid undergone a revision surgery with percutaneous posterior stabilization with C1/C2-screw fixation. All patients received an initial anterior screw fixation with one or two screws. In the absence of fracture healing, or screw loosening with pseudarthrosis of the odontoid a revision surgery was performed with percutaneous posterior stabilization with C1/C2- screw fixation. The surgery was performed with 3D image converter for documentation of the reposition preoperatively and postoperatively to control the screw position. Intraoperative the percutaneous approach was documented with the exact image converter in two planes, ap and strictly laterally. Postoperative clinical controls were performed and CT inspection to document the stability and healing of the pseudarthrosis of the odontoid within a year. Results: In the period from January 2007 to December 2012 in 10 patients with unstable pseudarthrosis of the odontoid after previous anterior screw fixation, were stabilized with the posterior stabilization with percutaneous screw fixation C1/C2. 4 women and 6 men with a mean age of 69.8 years / - 7.7 (median 70, min 57, max 82) were stabilized. The mean OR-time was 59.9 min / - 38.8 (median 45, min 36, max 165). In the mean follow-up of 382 days / - 324 (median 273), all patients had a stable course. In 8/10 patients healing of the pseudarthrosis of the odontoid could be demonstrated by CT. In 3/10 the dorsal screws were removed. Conclusion: The C1/C2 dorsal percutaneous screw fixation for unstable pseudarthrosis of the odontoid is a safe and promising, the patient little burdensome procedure. With the help of 3D imager the operating profit can be improved. Especially the older patients benefit from this supply strategy with high healing of the pseudarthrosis of the odontoid. The metal removal can be effected by healing of the pseudarthrosis of the odontoid, and thus the C1/C2-Joint can be given free again.

P359 - Results in Dorsal Percutaneous C1/C2-Screw-Osteosynthesis in Unstable Odontoid Fractures Type Anderson 2 in the Elderly

Stefan Hauck¹, Jan Vastmans¹, Thomas Weiss¹, Oliver Gonschorek¹

¹Spine surgery, Murnau - Germany

Introduction: For the surgical treatment of unstable odontoid fractures in old age several surgical procedures are possible: - direct anterior screw fixation of the odontoid - dorsally by C1/C2-screw-osteosynthesis, open with iliac crest bone graft and cerclage (n.Gallie) or - dorsally by C1/C2-screw-osteosynthesis percutaneously with two C1/C2-screws.

The ventral direct screw in osteoporotic bone metabolism is not successful, the dorsal C1/C2-screwing in open technique with iliac crest bone graft and cerclage is very stressful for the elderly. The percutaneus C1/C2-screw-osteosynthesis can lead to healing of the odontoid fracture; after completion of the fracture healing the screw fixation can be removed. Material and Methods: In a prospective study 32 patients with unstable odontoid fracture and an age over 60 years were stabilized with percutaneous posterior dorsal screw fixation C1/C2. The surgery was performed with 3D image converter for documentation of the reposition preoperatively and postoperatively to control the screw position. Intraoperative the percutaneous approach was documented with the exact image converter in two planes, ap and strictly laterally. Postoperative clinical controls were performed and CT inspection to document the stability and the healing of the fracture of the odontoid within a year. Results: In the period from January 2007 to December 2012 was carried out in 32 patients with unstable odontoid fractures with percutaneous screw fixation C1/C2 posterior stabilization. 17 women, 15 men with a mean age of 81.8 years / - 7.5 (median 84, min 57, max 91) were stabilized. The mean OR-time was 50.0 min / - 24.3 (median 44.5, Min 16, Max 123). In the mean follow-up of 117 days / - 244 (median 29.5), all patients had a stable course. In 12/32 patients the healing of the fracture could be demonstrated by CT, in 3/32 the metal was removed. Conclusion: The C1/C2 dorsal percutaneous screw fixation of unstable odontoid fractures is a safe and promising, the patient little burdensome procedure. With the help of 3D-imaging operating profit can be improved. Especially the older patients benefit from this supply strategy with high healing rate of the fractures. The metal removal can be effected by fracture healing of the odontoid, and thus the C1/C2-joint can be given free again.

Trauma - Other

P360 - Imaging Modalities for the Acutely Traumatized Spine Patient with Ankylosing Spinal Disorders: The Utility of Mri Beyond Baseline CT

Richard Bransford¹, Samia Ghaffar¹, Carlo Bellabarba¹

¹Department of Orthopaedics, Harborview Medical Center, Seattle - United States

Introduction: Ankylosing spinal disorder (ASD) patients are at a greater risk for spinal fractures due to osteoporosis and rigidity of the spinal column. The estimated incidence is four times that of the normal population, with neurologic compromise resulting from delayed or missed diagnoses due to difficulty of diagnosing contiguous fractures. Many propose that a MRI is mandatory in addition to a CT in ASD patients to identify fractures, ligamentous injury, and cord signal abnormalities. Studies have also shown that MRIs can cause further neurological injury due to positioning. The purpose of our study was to assess the frequency with which an MRI identified an injury NOT previously identified on CT, and whether this affected the management and outcome of the patient. Material and Methods: After obtaining IRB approval, a retrospective assessment of the radiology database at a level I institution was undertaken from 2005 to 2015 to identify patients with ASD who sustained an acute fracture. Patients were included if they had a CT and MRI upon admission. Final radiology reports were assessed to determine presence and type of fracture(s) from CT. MRI report was then reviewed to assess if additional fractures or injuries were identified beyond that already known from the CT. Neurologic status upon admission, mode of injury, type of fracture and final intervention was determined by inpatient notes and/or operative reports. Results: In the designated time frame, 124 patients were identified. Neurologic status was classified as follows: 14 ASIA A, 5 ASIA B, 3 ASIA C, 12 ASIA D, and 70 ASIA E. Twenty had an unknown neurological status due to exams unable to be performed due to head injury or mental status issues. Six patients (4.8%) had additional injuries on MRI that had not been identified on CT. Four of these six patients had a change in treatment plan based off of subsequent MRI findings. These included a 1) C3-4 extension injury, 2) C6-7 extension injury, 3) C5-T4 epidural hematoma, and 4) C5-C6 extension injury treated in a brace. Two of the six patients that had additional injuries identified on MRI had no change in their treatment plan. One patient had an additional lumbar extension injury noted above previously identified injury on CT, which was managed in the original TLSO plan. The last patient died due to a cord transection with no treatment. Conclusion: In this study, 3.2% (4/124) of patients with ASD who presented to a level I trauma center with an acute fracture had treatment plans that changed based off of the MRI. All patients in whom the management changed had symptoms which warranted further investigation. Two patients were incomplete cord injuries (ASIA C and D) and the other two were ASIA E with paresthesias and severe pain. Based off of these results, it may be beneficial to obtain a MRI in ASD patients with negative CT scans who report motor weakness and/or sensory changes or else if there is severe pain.

P361 - Kyphoplasty and Vertebroplasty in the Treatment of Osteoporotic Vertebral Compresion Fractures

Uriel Nahum Garcia Ortiz¹, Miguel Angel Fuentes Rivera¹, Amado Gonzalez Moga¹, Hugo Alberto Santos Benitez²

¹Department of Spine Surgery, ISSEMYM Ecatepec Medical Center, - Mexico ²Cerebral and Vertebral Neurosurgery Unit, Ruber Juan Bravo Hospital, Madrid - Spain

Introduction: Osteoporosis is a public healthcare problem worldwide, with one of the most common complications being vertebral compression fractures, representing 1.4 million patients per year. Even though the gold standard of treatment is conservative management, patients may have persistent pain, lower quwwality of life and even higher rates of mortality. Vertebral augmentation has appeared as an effective method of treatment, reporting better management of pain and quality of life. Controversies exist between which method is superior and if the number of portals affect the results. The objective of this study is to compare kyphoplasty and vertebroplasty in the treatment of vertebral compression fractures. Material and Methods: The study took place in Ruber Quiron Juan Bravo Hospital. Patients who underwent kyphoplasty or vertebroplasty due to osteoporotic vertebral compression fractures in the period of March 2010 to October 2016 were eligible, independent of the number of levels fractured. Patients with prior spine surgery, and fractures due to other reasons (eg. metastatic) were excluded. Kyphosis, anterior vertebral height, Oswestry Disability Index (ODI) and Visual Analog Scale (VAS) pre and postsurgery were recorded, as well as number of portals, amount of bone cement, and complications. A p value lower than 0.05 was established as statistically significant. Results: 68 patients were eligible, accounting for a total of 105 procedures. An improvement in ODI and VAS scales was observed in both procedures (p < 0.001). There was no statistically significant difference between Kyphoplasty and Vertebroplasty in the means of ODI, VAS, kyphosis correction, and anterior vertebral height improvements. No difference was observed with the use of one or two portal, or with the amount of bone cement applied. A high correlation between kyphosis correction and ODI improvement was observed (0.905, p = 0.012) Conclusion: Kyphoplasty and Vertebroplasty are effective procedures in the treatment of osteoporotic vertebral compression fractures. We found no statistically significant differences between both procedures, the number of portals used, and the amount of bone cement applied in the means of ODI, VAS, kyphosis correction, and anterior vertebral height improvements. The high correlation found between kyphosis correction and ODI improvement suggests these procedures may be superior to conservative treatment for the improvement of life quality, however more studies comparing vertebral augmentation and conservative treatment are necessary.

P362 - Place of Internal Fixation in the Management of Gunshot Pelvic Fractures

Saber Saadi¹, Ahmed Tounsi¹, Khalil Amri¹, Karim Tlemsani¹, Abderrazek Rafrafi¹, Lotfi Nouisri¹

¹Department of Orthopedics, the Military Hospital of Instruction of Tunis, Tunis - Tunisia

Introduction: The management of ballistic fractures in the civilian context has largely benefited from military practices including debridement and lavage but is distinguished from those occurring in a military context by the possibility of internal fixation in bone stabilization. The purpose of our work is to show the place of internal fixation in the management of pelvic ballistic trauma in the civilian setting. Material and Methods: We report the case of a 36-year-old civilian patient, victim of a firearm injury causing pelvic ballistic trauma. Injuries were caused by damped projectile. The initial clinical examination showed the presence of a bullet’s entrance in the right iliac fossa without an exit orifice, associated with a complete cauda equine syndrome at S1 level without vascular lesion. The standard radiography showed deposits of barium titanate and a complex sacral fracture. The computed tomography scan showed an associated rectal perforation. The patient was initially cared for in the surgery department where he had debridement and lavage, colostomy and transrectal drift of the temporary cavity. Seen the mechanical instability of the pelvis, an internal fixation was done by a left unilateral lumbar-iliac fitting. To compensate for the loss of bone substance of the sacrum and to ensure a permanent pelvic stability, a bone graft of fibula has been fixed between L3 and the iliac wing. Results: The restoration of colonic continuity was performed after 4 months. The removal of the lumbar-iliac fixation was performed at one year. At mean 24-month follow-up the patient did not present infectious complications, does not complain of pain with restoration of walking with canes of crutches. The radiological results confirmed the bone consolidation of the fracture and graft site. Conclusion: The treatment of ballistic fractures in the military and civilian context is based on the principle of debridement and lavage which remains univocal but differs in bone stabilization. In fact in the civil context the use of internal fixation is possible, allowing bone consolidation and mechanical stability without increasing the infectious risk which remains the major complication to be feared.

P363 - Medullary Lesion in the Brazilian Setting: Systematic Review and Meta-Analysis

Thiago Maia¹, Charbel Jacob Jr¹, Igor Machado Cardoso¹, José Lucas Batista Jr¹, Marcus Alexandre Novo Brazolino¹, Flavia Schulthais da Silva¹, Gabriel Donato Amorim¹

¹Department of Orthopedics, Santa Casa de Vitoria, Vitoria - Brazil

Introduction: Due to the great relevance and severity of the spinal cord injuries, are directly related the damage of the affections to public policy factors in economic, social and for the development of Brazilian health, and it is therefore fundamental to build a national epidemiological profile of the spinal cord injury, until then non-existent for the standardization of actions and a more efficient treatment for each lesion with its possible complications. Materials and Methods: National epidemiological studies were compared in patients with spinal cord injury, and data and information from the researched articles were analyzed in the form of a systematic review with reference to the Ministry of Health Guideline on Methodology for Systematic Review and Meta-Analysis. The research bases used were PUBMED / MEDLINE and LILACS / BIREME. The 128 articles resulting from phase 1 were intended for screening. At the end of the systematic review, 9 studies were selected. These deliberate studies were analyzed and from these we collected information and epidemiological data that were compared statistically by meta-analysis. Results: The review reveals that the main sex involved in spinal cord injuries is predominantly male, with a mean of 79.41% of the total, while the female sex represents only 20.50% of the cases. The mean age of greatest involvement is 36.26 years. The cases of spinal cord injuries include traffic accidents with 29.05% (car accidents, motorcycle accidents, trampling), causes of violence of 26.22% (injury caused by firearm, white weapon, aggression), falls with 23, 48% (drop in height, decrease in height), dip with 7.76%, and other causes, such as tumor compression, surgical accidents and anesthetics, and no description with 10.82%. The segment of the most affected spine was thoracic, with 41.56% of the total, followed by cervical spine with 30.89%, lumbar spine with 18.80%, and in other places with 8.59%. Conclusions: Considering the high average number of patients per article and the representativeness of the country’s extension, this review is appropriate to understand the different types of causes of spinal cord injuries and their respective prevalences in the Brazilian population, as well as to have a detailed analysis of the characteristics of the affected individuals, such as gender, age group, main sites of involvement and casuistry. Therefore, it is a study basis for the construction of public health prevention and promotion policies in the country for this aggravation.

P364 - Spinal Fusion in a Developing Country: A Neurosurgical Perspective

Peter Wanyoike¹

¹BSR Hospital, Nairobi - Kenya

Introduction: In a developing country like Kenya fusing the spine is a big challenge. This is not only because of the low number of trained spine surgeons (orthopedic and neurosurgeons) but also the expense of modern reconstruction implants. It costs $2000 for the cage, plate and screws plus B.M.P, if you add $2,000 for five days hospitalization and professional fee of $3000, the total cost is estimated at $ 7,000, way above the income bracket of most in developing countries. The scope of spinal fusion in Kenya is currently not known (who is doing what and for what indications). A multidisciplinary approach is required for better patient management and attempts at standardization. The authors present experience with 150 cases of spinal fusion both in private and public service. Degenerative causes were the most common followed by trauma. Material and Methods: A retrospective review of cases performed by the author in various hospitals in Kenya both urban and rural settings. Review of records from both public and private hospitals over a 5 year period from 2012 to 2017. Results: A total of 148 cases were reviewed ranging from non-instrumentation C1 and C2 fractures (4), ACDF (42 or 28%), thoracic (15), thoraco-lumbar (38), lumbar (47 or 31%). 4 patients were fitted with halo jacket for C1 and C2 fractures while all cervical injuries were treated with a peek cage plate and screws. 22 Patients with thoracic and thoraco-lumbar injuries had anterior transthoracic corpectomy interbody cage and lateral plate or rod fusion. The rest had posterior pedicle screw fusion. Conclusion: The scope of spinal fusion in Kenya is currently not known (who is doing what and for what indications). A multidisciplinary approach is required for better patient management and attempts at standardization. Development of centers of excellence, more training and low priced but quality implants will change the demographics like our Northern and Southern Africa counterparts.

P365 - Outcome of Early Surgical Intervention in Spinal Trauma Patients, An Overview of 109 Spinal Trauma

Ammar Dogar¹, Haseeb Hussain¹, Ashfaq Ahmad¹, Amer Aziz¹, Shahzad Javed¹, Rizwan Akram¹

¹Dept of Orthopaedics and Spine Surgery, Ghurki Trust Teaching Hospital, Lahore - Pakistan

Introduction: The prognosis for spinal cord injuries varies depending on the severity of the injury. There is always hope of recovering some function with spinal cord injuries. The completeness and location of the injury will determine the prognosis. The sooner treatments are implemented to strengthen muscles below the level of the spinal cord injury, the better the prognosis. The first year of recovery is the hardest as the patient is just beginning to adjust to his or her condition. The use of physical and occupational therapy during this time is the key to recovery. The extent of the function fully returning is typically seen in the first two years after the initial injury. To determine the neurological outcome of patients who presented early with those whose presented late. Materials and Methods: It is a descriptive case series done in the Department of Orthopaedics and Spine between Jan 2014 to Dec 2016. 109 patients who presented to ER or OPD with spinal trauma were included. Those patients who were operated else where or having trauma of more than 10 days or those who were managed conservatively were excluded. After admission, history, examination and investigations surgical intervention was done on same day. Every patient was followed regularly for 2 years to assess the neurology. The data was analyzed using SPSS 17.00 Version. Results: There were 109 total patients that presented with spine trauma. 74 (67.9%) were male and 35 (32.1%) were females. Male to female ratio was 2.11:1. Of the 109 total patients that presented 78 (71%) were below 40 years of age and 41(28.5) patients were above 40.17 (15.6%) had trauma to the cervical spine, 34 (31.2%) to the thoracic spine, 3 (2.8%) to the thoracolumbar spine and 55 (50.5%) to the lumbar spine. 79 (72.5%) patients had a fall from height. 26 (23.9%) were involved in road traffic accidents. 1 (.9%) had assault and 3 (2.8%) had sports injuries. At the time of presentation out of 109 patients, 97 (89%) had their neurology involved while 12 (11%) had intact neurology. 18 (16.5%) presented within the first 24 hrs while 91 (83.5%) presented after 24 hrs. All the patients were operated on the same day of admission. Among the 18 patient who presented with in 24 hours, 17 patients having full recovery with in 12.66 ± 1.2 months. While the late presenters only 15 patients got fully recovered after 2 years follow up while 42 patients having partial neurology recovery and 24 having just sensory improvement and 28 having no improvement after two years follow up. Conclusion: Spinal trauma is an emergency and having high morbidity and mortality rate. Early presentation and surgical intervention in spinal trauma patients having good neurological outcome as compared to delayed presentation and surgery.

P366 - To Develop a Data Set for National Spinal Cord Injury Registry of Iran (NSCIR-IR)

Kazem Zendehdel¹, Seyed Behzad Jazayeri², Zahra Azadmanjir², Vafa Rahimi-Movaghar³

¹Cancer Research Center, Cancer Institute of Iran, Tehran University Medical of Sciences, Tehran - Iran, Islamic Republic ²Sina Trauma and Surgery Research Center, Tehran University of Medical Sciences, Tehran - Iran, Islamic Republic ³Sina Hospital, Tehran - Iran, Islamic Republic

Introduction: The development of a data set is an essential step for designing a registry system. The aim of present study was to develop a data set for National Spinal Cord Injury Registry of Iran (NSCIR-IR). Material and Methods: NSCIR-IR data set was developed during 8 months, from March to October 2015. An expert panel of 14 members was formed. After review on data sets of similar registry centers in developed countries, the selection and modification of the basic framework was performed based on the objectives and feasibility during sixteen meetings. Results: NSCIR-IR data set was developed using the International Spinal Cord Injury Data Set (ISCIDS) as the main resource. The final version of data set was composed of 350 data elements included sociodemographic, hospital admission, injury incidence, pre-hospital procedures, emergency department, medical history, vertebra injury, other injuries, SCI, interventions, complications in the acute phase, discharge, pressure ulcer, pain, and spasticity categories. In addition, 163 components of American Spinal Injury Association neurological assessment along with the 26 questions of WHOQOL-BREF questioner were included. Conclusion: NSCIR-IR data set was developed in order to meet the quality objectives of the registry. Data elements focus on data demonstrating how to provide appropriate care in hospitals for patients in acute and chronic phase of Traumatic SCI. The Selected ISCIDS as a basic framework of data set, can use in order to help comparison with data from other countries. Expert panel modifications facilitate the integration of the registration process with the current clinical practice in hospitals.

The study was supported by Ministry of Health and Medical Education of Iran and AOSpine of Middle East.

Trauma - Thoracolumbar

P367 - Minimally Invasive Pedicle Screw Fixation Plus Pvp with Calcium Phosphate for the Surgical Treatment of Thoracolumbar Burst Fracture

YuTong Gu¹

¹Department of Orthopaedics, Zhongshan Hospital of Fudan University, Shanghai - China

Introduction: Traditional short-segment pedicle instrumentation for the treatments of thoracolumbar burst fracture was frequently applied into the adjacent intervertebral bodies of the injuried vertebrae, but with a high failure rate for the later factors including osteoporosis, insufficient support of anterior column, and lack of enough fixation segments. In addition, the traditional screw implantation, which commonly use a posterior midline approach, resulted in great trauma and blood loss, as well as slow recovery, for the extensive split of muscles. We designed minimally invasive pedicle screw fixation (noncannulated pedicle screw insertion under direct vision through minimal-access in a paraspinal sacrospinalis muscle-splitting approach and rod placed over the pedicle screws through subcutaneous soft tissues and muscles) plus PVP with calcium phosphate for treating acute thoracolumbar burst fracture to reduce the trauma, blood loss and failure rate. The aim of this study was to evaluate the feasibility, safety and efficacy of this method. Materials and Methods: Twenty-three patients with a mean age of 51.6 years (ranging 40-63 years), who sustained thoracic or lumbar fresh burst fracture without neurologic deficits underwent the procedure of minimally invasive pedicle screw fixation plus PVP with calcium phosphate. Visual analog scale pain scores (VAS) were recorded, and Cobb angles and anterior vertebral body height were measured on the lateral radiographs before surgery and immediately, 1 month, 2 months, 3 months, 6 months, 1 year and 2 years after surgery. Results: The mean duration of the operation was 92 minutes (range 75-120 minutes). The mean blood loss was 52 ml (range 40-75 ml), and no blood transfusions were required. The mean stay in the hospital was 5.6 days (range 4-7 days). The patients were followed for an average of 26 months (ranging 24-29 months). The VAS significantly decreased from 8.8 ± 1.2 before surgery to 1.8 ± 0.6 immediately after surgery and 0.4 ± 0.5 (P < 0.001) 2 years after surgery. The Cobb angle before surgery was 22.6 ± 1.8° and 3.2 ± 1.7°(P < 0.001) immediately after surgery. The compression rate of vertebral body height decreased from 50.4 ± 7.2% before surgery to 6.2 ± 1.5% (P < 0.001) immediately after surgery. No significant changes in both kyphosis correction and vertebral body height restoration obtained were observed 2 years after surgery. There was no patient with the failure of instruments during the follow-up. Conclusions: Minimally invasive pedicle screw fixation plus PVP with calcium phosphate is a good choice for the treatment of acute thoracolumbar burst fracture.

P368 - Percutaneous Vertebroplasty Versus Conservative Treatment for Osteoporotic Vertebral Compression Fractures: An Updated Meta-Analysis of Prospective Randomized Controlled Trials

Lin Xie¹

¹Wuhan Puai Hospital, Wuhan - China

Introduction: This meta-analysis of Randomized Controlled Trials (RCTs) aims to evaluate the efficacy and safety in percutaneous vertebroplasty (PVP) and conservative treatment (CT) for osteoporotic vertebral compression fractures (OVCFs). Material and Methods: The authors searched RCTs in electronic databases (Cochrane Central Register of Controlled Trials, PubMed, EMBASE, Medline, Embase, Springer Link, Web of Knowledge, OVID and Google Scholar) in a timeframe from their establishment to Feb 2017. We also manually searched the reference lists of reports and reviews for possible relevant studies. Researches on PVP versus CT in OVCFs were selected in this meta-analysis. The quality of all studies was assessed and effective data were pooled for this meta-analysis. The outcomes were measured by pain relief (one week, one month, three months and six months), quality of life (RDQ, ED-5Q and QUALEFFO) and the rate of adjacent vertebral fracture. Publication bias assessment was also performed, respectively. The meta-analysis was performed using RevMan 5.1. Results: 13 reports (12 RCTs) with a total 1231 patients (623 in the PVP and 608 in the CT) met inclusion criteria. Patients were followed up for at least 2 weeks in all the studies. Statistical differences were found between pain relief (one week (MD 1.36, 95% CI (0.55, 2.17)), one month (MD 1.56, 95% CI (0.43, 2.70)) and six months (MD -1.59, 95% CI (-2.9, -0.27))) and QUALEFFO (MD -5.03 95%CI (-7.94, -2.12)). No statistical differences were found between pain relief (three months (MD -0.28, 95% CI (-1.46, 0.90))), RDQ (MD -0.59, 95% CI (-1.31, 0.13)), ED-5Q (MD 0.10, 95% CI (-0.01, 0.22)) and the rate of adjacent vertebral fracture (RR 1.21, 95% CI (0.89, 1.62)). Conclusion: PVP is associated with higher pain relief than CT in the early period. Furthermore, PVP did not increase the rate of adjacent vertebral fracture. The results indicate that it is a safe and effective treatment for OVCFs. Because of some limitations, these findings should be interpreted with caution. Additional studies are needed. Large, definitive RCTs are needed.

P369 - Long Term Results From a Pilot Monocentric Investigator Initiated Study to Compare the Safety and Effectiveness of Two Vertebral Compression Fracture Reduction Techniques

David Cesar Noriega Gonzalez¹, Francisco Ardura¹, Ruben HernandeZ Ramajo¹

¹Orthopedic Department, Valladolid University, VALLADOLID - Spain

Introduction: Vertebral augmentation techniques are widely used for the treatment of painful osteoporotic vertebral compression fractures. The aim of the study is to compare the safety and effectiveness of an expandable intravertebral implant (SJ) with the Inflatable Bone Tamp (BK) for use in fracture reduction procedures in osteoporotic patients with painful VCFs. Materials and Methods: This study was designed as a prospective, comparative, randomized, pilot study, and was approved by the local ethics committee. 30 patients, with painful osteoporotic fractures were included: SJ (n = 15), mean age: 67.9 years (61-74); BK (n = 15), mean age: 68.3 years (56-75). Globally 33 vertebral fractures were treated. Vertebral fractures were assessed using the Genant classification: wedge fractures: 88%, biconcave fractures: 6%, crush fractures: 6%. The severity of the fractures graded from 0 to 3: mild grade 1: 27%; moderate grade 2: 40%; severe grade 3: 33%. There were no statistically significant differences between both groups for demographics and pre-operative baseline characteristics. The time interval from symptoms appearance to the surgery was a mean of 28.2 days. The mean quantity of cement injected: SJ 4.9 ± 1.3 ml, BK 5.1 ± 1.3 ml. Clinical parameters: Pain (VAS), functional capacity (ODI). Radiological parameters: Vertebral height ratio (AVBHr, MVBHr, PVBHr), vertebral kyphotic angle, pre-operative, immediate postoperative, and at 6, 12 and 36 months post-op. Results: Twenty-eight patients were followed-up at 3 years, two patients died during the follow-up period (1 SJ, 1 BK). The mean patient follow-up time was 37.1 ± 10.4 months in the SpineJack^® group and 38.0 ± 7.8 months in the balloon group. There was a statistically significant reduction in pain and functional disability in both groups. VAS: SJ 64.6 ± 16.1, BK 58.9 ± 14.2 (p < 0.001). ODI: SJ 57.2 ± 16.7%, BK 49.4 ± 13.9% (p < 0.001). Statistically significant differences between groups for anterior and midline height ratio were seen. AVBHr (mean ± SD): SJ 16 ± 14% immediate postop, 10 ± 13% at 3-year (p = 0.007) compared to BK 4 ± 8% postop, 0 ± 8% at 3-year. MVBHr: SJ 16 ± 14% postop, 10 ± 11% at 3-year (p = 0.034) compared to BK 6 ± 8% immediate postop, 3 ± 7% at 3-year. Vertebral kyphotic angle reduction; SJ 6.1° postop, 5.0° at 3-year (p = 0.003); BK 1.1° postop and no statistically significant reduction (-0.4°) at 3-year (p = 0.980). There is a statistically significant difference between the two groups (p = 0.002). One asymptomatic cement leakage (3.3%) was reported in the SJ group. 4 subsequent fractures (3 of them adjacent fractures: SJ:2, BK:1) were seen at the 1-year follow-up. One of these 3 adjacent fractures (in SJ group) was due to a new trauma (fall at 55 days post op). One new adjacent fracture was reported at the 3-years follow-up in the BK group. No device-related AE were reported. Conclusion: Long term results confirmed that both techniques are safe and efficient for the treatment of osteoporotic VCFs. Radiological results indicate that SJ procedure has a higher potential for maintenance over time of height restoration and kyphosis reduction in comparison to BK procedure.

P370 - Percutaneous Transpedicular Kyphoplasty with Ppma for Treatment of Vertebral Body Compression Fractures: Clinical and Radiological Results on 500 Cases

Gabriele Carrabs¹, Giovanni Sessa¹

¹Neurosurgery, Avellino - Italy

Introduction: Vertebral compression fractures of the thoracic and lumbar column caused by osteoporosis, metastasis or trauma may have a relevant socio-economic impact because of high incidence of relevant complications and deaths. Percutaneous kyphoplasty is a minivasive surgical procedure that relieve the pain not responding to conservative treatment, restore the height of the fractured vertebral body, reduce the segmental kyphosis and stabilize the fracture with polymethylmethacrylate bone cement (PMMA). Materials and Methods: The analisys was conducted on 500 patients operated on at our Institution between 2007 and 2017 for Magerl A1.1.and A1.2 compression fracture after failure of conservative treatment. Clinical (VAS for vertebral pain) and radiological (plain RX films in AP and LL projections for evaluation of kyphosis at 1,2,3 and six months) follow-up range from six months to ten years. Before surgery all patients experienced a cycle of conservative treatment with a mean duration of 3-4 weeks. Exclusions criteria adopted: vertebra plana (vertebral body height reduction > 90%); burst fractures; posterior wall of the vertebral body involvement with a reduction of spinal canal diameters > 20%; vertebral instability; A3 fractures; neoplastic epidural invasion from tumour; local infections; haemorragic syndromes; cardiorespiratory insufficiences. We always performed local anesthetic infiltration of skin, fascia, muscles and vertebral bone, transpedicluar approach with fluoroscopic AP and LL check of procedural steps. Results: We performed 500 percutaneous kyphoplasties on 460 patients (348 F and 112 M - 75,65% and 24,35%), with a median age of 72,3 years (range 16-93 years). The procedure was performed in two months on 80% of patients, in six months on 10% and in 1 yera on 10%. We performed: 410 biportal procedures and 90 monoportal procedures. We collected: 310 osteoporotic fractures, 185 post-traumaticfractures and 5 metastatic fractures. 122 vertebral fractures were involved the thoracic spine and 378 the lumbar spine. One level was fractured in 340 patients, two levels in 158 and three levels in 2 cases. The execution time of surgical procedure range from 20 to 45 minutes. Surgical complications involved 4 patients: intradiscal injection of PMMA without clinical sequelae. We don’t experienced PMMA extravasation in the spinal canal, hypotension, embolic events, infections of the surgical site, adjacent vertebral fractures or pseudarthrosis in any case. All patients reported absence of pain at 72 h from surgical treatment and at three months all occupied patients returned to their job. In 80% of cases we registered a vertebral body augmentation > 40%. Conclusion: The percutaneous transpedicular kyphoplasty is a minivasive surgical procedure, with low cost, of brief duration, easy to perform, useful for thoracic and lumbar compression (not burst or instable) fractures that provide a rapid pain relief and prevent the vertebral body collapse and the pseudoarthrosis with consequential spinal kyphosis.

P371 - Burst Thoracolumbar Fractures Treated by Mis Reduction and Fixation: Minimun 4 Years Prospective Study

David Cesar Noriega Gonzalez¹, Francisco Ardura¹, Ruben HernandeZ Ramajo¹

¹Orthopedic Department, Valladolid University, Valladolid - Spain

Introduction: Our aim was to study the safety and effectiveness of a new intravertebral expansive implant for the treatment of vertebral compression fractures type A3 Materials and Methods: Consecutive observational prospective study. We included patients with a vertebral fracture type A3 (Magerl classification before november 2013) with more than 20% of VB collapse, that underwent surgery between june 2008 and may 2013. The procedure consisted on the use of an intravertebral expansive implant to restore the vertebral body and endplates, and later fixation with PMMA, through a percutaneous approach. Demographic, medical and procedure data were collected. Clinical and radiological evaluations were carried out through the follow up, as well as VAS, ODI and EQ5D scales. All patients had a final visit in may 2017. Complications were recorded. Results: 44 patients were included; all of the patients had one only fracture.Mean age 56.4, 29 male and15 female, mean BMI 29.8, 82.8% of the fractures were located between T11 and L2. Leakage rate was 12.9%, and all of them were asymptomatic. Mean follow up was 66.8 months (48-103). All clinical scales improved significantly after the procedure. Anterior height improved 3.58 mm after surgery(p < 0.001), posterior height improved 2.95 mm after surgery, both of them maintained the restoration at final follow-up(p < 0.001). Vertebral body angle improved almost 4º at final follow-up(p < 0.001). Regional kyphosis improved 6º at final follow-up(p < 0.001). VAS score improved from 7.84 prep to 1.34 at final follow-up(p < 0.001). ODI prep was 81.4 and improved to 13 at final follow-up (p < 0.001). No patients needed re-surgery during the followup. Conclusion: Cement leakage rate is lower than those observed in bibliography. Maintaninance of the reduction at final follow-up is an interesting parameter that also correlates with and improvement in the quality of life. No complications related to the use of cement in the long term. This technique is effective and safe in the treatment of vertebral fractures type A3, both in short and long term.

P372 - Outcome of Spine Fixation for Unstable Fractures at Dorsolumbar Junction Including Fractured Vertebrae in Pedicular Screw Fixation

Waqar Alam¹

¹Department of Orthopedics District Headquarter Hospital Timergara, Timergara - Pakistan

Introduction: Injury of the spinal cord with loss of neurological function is the most devastating life-changing injury. In the United States, spinal cord injuries occur at an annual rate of 30 cases per million inhabitants, which translates into 8000 new cases per year. Each year a large number of Pakistani population sustain spinal injuries. Studies on spinal injuries have been published in Pakistan but the exact incidence of spinal injuries in Pakistan is still unknown. Unstable vertebral burst fractures are two or three column fractures according tothe Three Column Concept of Denis and all vertebral fractures with more than 50% loss of vertebral height, more than 20 degrees angulation or more than 50% spinal canal compromise need surgical intervention. A uniform consensus has not yet been developed for the standard treatment of unstable burst fractures or fracture dislocation. With surgical spine fixation patients could expect to become mobile early, perform rehabilitative remedies, overcome anatomic fractures, and improve, in most cases, nervous functions by using decompression and fixation. Different procedures of posterior fixation of thoracolumbar spine fractures e.g. hooks and Harrington rods have undergone tremendous improvement over the last couple of decades. Moreover, pedicle screw fixation has revolutionized spinal surgeries all over the world. Short-segment posterior fixation is the most common and simple treatment. It offers the advantage of incorporating fewer motion segments in the fusion . There are biomechanical advantages of posterior fixation including the fractured vertebra (PFFV) over conventional short-segment fixation. It will be biomechanically stronger by inserting screws at the fracture level which in turn may omit the need for further anterior reconstruction. Studies have shown the inclusion of the fracture level in short segment fixation. This study was designed to evaluate the radiological and clinical results of transpedicular screw fixation of spine fractures including the fractured vertebra. Material and Methods: All patients with unstable single level fracture from D11 to L2 were fixed with transpedicular screws and rods. The fracture vertebra was included in the fixation by putting transpedicular screws in it. Patients were evaluated both radiologically by measuring anterior and posterior vertebral heights, Cobb angle and sagittal index. All these parameters were determined before surgery and immediately post-operatively. Results: A total of 23 patients with 16 males and 7 females having the mean age of 30.34 years (range 20 to 52 years) were enrolled in the study. Majority fractures were of L1 (n = 10) and D12 (n = 9). The mean Cobb angle was improved from preoperative 7.35 ± 4.57 to 2.18 ± 1.71post operatively. The pre-operative mean anterior and posterior vertebral height were improved from 17.45 ± 3.8 mm and 26.81 ± 5.291 to 27.02 ± 3.83 mm and 39.63 ± 3.59 mm respectively.The pre-operative average sagittal index of 17.42° was reduced to 6.83° post operatively. The Oswestry disability index was improved from pre-operative score of 67.14 ± 17.68% to 39.81 ± 20.56%. Visual analogue score was improved from pre operative 7.3 ± 1.3 to 2.4 ± 0.9 post operatively. No major complications were reported. Conclusion: Transpedicular screw fixation including the fractured vertebrae gave excellent radiological outcome results in majority of our patients.We therefore strongly recommend fixation of the fractured vertebra in transpedicular screw fixation of dorsolumbar spine fractures.

P373 - The Main Goal: Neurologic Recovery after Surgery of Thoracolumbar Fractures with Cauda Equina Syndrome. Case Series

Daniel Oscar Ricciardi¹, Gabriel Genaro Carrioli¹, Ignacio Gabriel Garfinkel¹, Guillermo Alejandro Ricciardi¹

¹Department of Orthopedic Surgery, General Acute Patients Alvarez Hospital, Buenos Aires - Argentina

Introduction: We present a series of patients with thoracolumbar fractures with cauda equina syndrome (CES) injuries with neurological recovery after surgical treatment. Objective is to evaluate the feasibility of surgical posterior approach only for the treatment of this type of lesions. Second objective is to determine the temporary incapacity for work of these patients. Materials and Methods: We present 4 cases of vertebral fractures from the thoracolumbar junction with neurologic deficit due cauda equina injuries treated for the same surgical team in Fitz Roy Medical Center (Buenos Aires, Argentina) in the period between august 2014 and august 2015. All of them were high energy trauma work accidents. Clinical records and imaging about patients were described. Values assessed were: Sex, Age, AOSpine Thoracolumbar Classification System, neurologic status (Frankel Scale) pre and postoperatively, surgical delay (days) and Temporary Incapacity for Work (TIW) (days). The TIW was defined according to Argentinian Law standards. All patients were treated by a standard posterior approach, extended posterolaterally to an egg shell technique plus a complete resection of posterior arch, resection of bony intracanal fragments and reduction by impaction of remaining posterior wall retropulsed fragments. Dura mater had to be repaired by local suture and patching. Poliaxial bi lateral pedicle screws were placed for a Posterior long segment fixation. Results: 21 thoracolumbar fractures were surgically treated. 11 cases had neurologic deficit: (5 cauda CES and 6 spinal cord involvement). 4 of the CES improved the neurologic status postoperatively. According to AOSpine Thoracolumbar Classification System and Frankel scale these cases were: L2-L1 C (L2 A4; N3) - Frankel, T12: A4 (N3;M1) -Frankel C, L2-L3: C (L2: A4;N3) - Frankel C and T12-L1: B (L1: A4;N3) - Frankel B. The average surgical delay since the diagnosis of neurologic deficit was 2,75 days (1-5). Three cases with initial Frankel C grade improved to Frankel E and one with Frankel B grade to Frankel C after surgical treatment. The average of TIW was 411,5 days (219-721), with one case of 721 days because of an oncological intercurrence (Hodgkin lymphoma). 1 patient return to the same previous work and the rest were reassigned. Conclusions: Our series seems to show that thoracolumbar fractures with neurologic deficit due to cauda equina injuries should be surgical treated as soon as possible once obtained clinical stability. The posterior approach with indirect reduction of the posterior wall fragments remains a valid and effective technique to treat this type of patients. The average of TIW was 411,5 days.

P374 -The Validity of the Thoracolumbar Injury Classification System in Thoracolumbar Spine Injuries

Sung Kyu Kim¹, So Hyun Moon²

¹Department of Orthopedic Surgery, Chonnam National University Hospital, Gwangju - Korea, Republic ²Department of Nursing, Chosun University, Gwangju - Korea, Republic

Introduction: This study evaluates the validity of TLICS when making treatment decisions to agroup of thoracolumbar fracture patients. Material and Methods: Retrospective study was performed among the 330 patients that were treated from 2000 to 2016 in our hospital for thoracolumbar injuries. Evaluation was done on clinical outcome and radiologic result and each case was analysed and scored according to the ASIA scale, Magerl/AO classification, TLICS classification. Results: 139 patients out of 330 patients (42.1%) received conservative treatment and 191 patients out of 330 patients (57.9%) received surgical treatment. 128 patients out of 139 patients (92.1%) who received conservative treatment showed correspondence to treatment recommended by TLICS. On the other hand, 160 patients out of 191 patients (83.8%) with surgical treatment showed correspondence with the treatment recommended by TLICS. Conclusion: TLICS classification showed high validity for conservative treatment of thoracolumbar injuries.

P375 - Clinico-Radiological Outcomes of Posterior Surgery (Decompression + Instrumentation + Transpedicular Bone Graft) in Osteoporotic Burst Fracture Associated with Neurological Deficit [OFND]

Mahendra Singh¹, Vishal Kundnani², Tarun Dusad², Gaurav Mehta¹

¹Dept of Orthopedics and Spine Surgery, Mumbai - India

Introduction: Surgery in neurological deficit due to delayed collapse of non-healing osteoporotic fractures is often met with complication due to associated co-morbidity and potential of instrumentation failure. Management of OFND is controversial. Material and Methods: 40 patients with neurological deficit due to delayed osteoporotic vertebral collapse managed by posterior surgery (decompression + instrumentation + transpedicular bone graft) with minimum 2 years follow up included. Demographic data (age, sex, mode of injury, severity of osteoporosis, duration of delay in presentation); clinical parameters [Visual Analogous score (VAS), Oswestry Disability Index (ODI), Frankel grade], radiological parameters (local kyphosis), surgical variables (blood loss, surgery duration, intra-operative problems) recorded. Neurological worsening /improvement, complications, implant loosening /failures were noted. Results: Significant improvement noted in VAS (pre-op 8.20 ± 0.65/post-op 4.1 ± 0.64), ODI (Pre op 76.54 ± 6.96/Post op 30.5 ± 6.56). Complete neurological recovery noted in 37 patients (Frankel grade E), 3 patients remained non ambulatory (Frankel grade C). Significant improvement noted in local kyphosis angle (pre op = 21.80 ± 2.7⁰; post op 11.40 ± 1.8⁰), with 10% loss of correction (2.5+/-0.9⁰) at final follow up. Symptomatic implant failure was noted in 2 patients and proximal junctional failure in 1 patient requiring revision. Conclusion: OFND can be managed with single posterior surgery (decompression + instrumentation+ transpedicular bone-graft) with significant improvement in neurology and functional scores of patient. Aggressive kyphosis correction often not required and significant correction of kyphosis is noticed due to positioning alone. Transpedicular grafting is safe and simple alternative to cement augmentation or anterior surgery for collapsed vertebrae.

P376 - Outcome of Short Same-Segment Fixation of Thoracolumbar Burst Fractures Using Pedicle Fixation at the Fracture Level

Umair Nadeem¹, Shahzad Javed¹, Naeem Ahmed¹, Atiq Uz Zaman¹, Amer Aziz¹

¹Department of Orthopedic and Spine Surgery, Ghurki Trust Teaching Hospital, Lahore - Pakistan

Introduction: Preservation of as many motion segments as possible is highly desirable with spinal fixation for trauma. This could be possible with traditional short segment posterior fixation, but it was found to have high incidence of implant failure and poor functional outcome. Short segment posterior fixation with transpedicular screw fixation at the level of the fracture (Short Same-Segment Fixation) is reported to provide a number of biomechanical advantages: better maintenance of kyphosis correction and decreased risk of implant failure. However, how much of that holds true in clinical terms, remains to be seen. Methods: A retrospective review of 71 thoracolumbar burst fractures treated with short same-segment fixation at Ghurki Trust Teaching Hospital, Lahore was done from January 2013 to December 2015. Patients presenting with thoracolumbar spinal trauma were initially treated following ATLS protocol. Thorough radiographic evaluation was done including CT and MRI. After informed consent, short same-segment fixation of burst fractures was done using locally made titanium mono-axial transpedicular screws. Outcome was measured in terms of incidence of hardware failure and loss of kyphosis correction within the follow-up period. Long-term function was assessed using Oswestry Disability Index. Results: Mean age was 34.2 ± 12.65 with 53 (74.6%) males and 18 (25.4%) females. Average duration of the follow-up was 18.23 months (range 4 to 37 months). Three patients (4.2%) presented with implant failure or pseudoarthrosis. Mean pre-operative kyphosis was 16.8°. Mean post-operative kyphosis was -1.63° (lordosis). Average loss of kyphosis correction from post-operative time to last follow-up was 13.5° (P < 0.0001). At one month follow-up, average Oswestry Disability Index score was 58.7% (range 22% to 91%). At last follow-up, the average score improved to 6.2% (range 1% to 19%). Two patients were lost to follow-up. Conclusions: Although not as favorable for maintenance of kyphosis correction, short same-segment fixation of thoracolumbar burst fractures using transpedicular fixation at the fracture level results in a low rate of hardware failure. Moreover, long-term disability and pain is considerably reduced.

P377 - Results with a Trabecular Metal – Cage for the Monosegmental Thoracoscopic Spondylodesis of Fresh Unstable Thoracolumbar Spinal Fractures in 95 Cases

Stefan Hauck¹, Thomas Weiss¹, Oliver Gonschorek¹

¹Spine 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 January 2010 to December 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.

Abb. 1

P378 - Percutaneous Fixation of Thoracolumbar Fractures. Does Index level Fixation Help in Fracture Reduction and Stability?

Tarek ElHewala¹, Amr El-Adawy¹

¹Spine Unit, Department of Orthopedic, Faculty of Medicine, Zagazig University, Zagazig - Sharkia - Egypt

Introduction: Thoracolumbar burst fractures are caused by compression injury with subsequent loss of vertebral height and development of local kyphotic deformity. The application of pedicle screws in the fractured vertebrae i.e. index level fixation, had been proven to help in reduction and correction of the local kyphotic deformity and anterior vertebral height loss with their maintenance in short segment fixation. Recently, percutaneous pedicle screws are introduced and used in the thoracolumbar fracture fixation with the proposed advantage of the less soft tissue dissection, muscle disruption and atrophy and assumed less wound related complications. Controversy remains about the ability of the percutaneous instrumentation to reduce and maintain the correction of local kyphosis and lost vertebral height caused by the fracture compared to the open instrumentation. Material and Methods: In this prospective study, thirty-eight neurologically intact patients with thoracolumbar burst fractures (T11-L2) type A3 and A4 according to AOSpine classification were treated between 2012 and 2015 with posterior pedicle screw fixation. The patients were divided into two groups, group 1 included 18 patients treated with percutaneous pedicle screws (PPS) while group 2 included 20 patients treated by standard open posterior approach with pedicle screws fixation (OPS). The operative data (blood loss, radiation exposure, operative time, and cost of implants) were compared between the two groups. The patients’ radiographs were assessed for local kyphotic angle (LKA) and anterior vertebral body height (AVH) compression and compared for correction and maintenance. The patients’ visual analogue scale (VAS) for back pain and treatment related complications were reported. Results: The blood loss was the only operative parameter that was significantly less in the PPS group and although the operative time decreased in the PPS group by the increase in learning curve, the other operative data show significant difference in favor of the OPS group. Post-operative correction of the local vertebral compression assessed radiologically with LKA and AVH significantly improved in both groups compared to the pre-operative degree and was maintained till the end of follow up. No major wound related complication was found in both groups. VAS of back pain was significantly reduced in PPS group in the early postoperative follow up than the OPS, but both groups at the end showed a significant improvement between early post-operative and late follow up. Conclusion: Percutaneous pedicle screw fixation is a good minimally invasive modality in the management of thoracolumbar fractures and the application of screw in the fractured vertebrae improves the correction and maintenance of local kyphosis in short segment fixation. Cost effectiveness of this technique must be evaluated thoroughly with the final and late outcome of this management. More randomized controlled and multicenter studies are needed to support these findings.

P379 - Minimally Invasive Treatment of Vertebral Body Ffractures Supported with Cranio-Caudal Expandable Implant (SPINEJACK)

Stanislaw Adamski¹, Wojciech Kloc², Witold Libionka³, Rafal Pankowski⁴, Marek Roclawski⁴, Patryk Kurlandt¹, Maciej Racinowski¹, Jakub Wisniewski¹, Piotr Murawski¹

¹Departament of Neurosurgery, Copernicus Hospital, Gdansk - Poland ²Department of Neurology and Neurosurgery, Faculty of Medical Sciences, University of Warmia and Mazury, Olsztyn - Poland ³University of Physical Education and Sport, Gdansk, Gdansk - Poland ⁴Department of Orthopaedics, Medical University, Gdansk - Poland

Introduction: The aim of study is assessment of clinical and radiological outcome for traumatic vertebral body fractures supported treatment with cranio-caudal expandable, intravertebral implant (SpineJack) in combination with cement and in some instances with transpedicular percutaneous stabilization. Methods: From May 2014r to June 2017 consecutive 58 patients (41 males and 17 females) with traumatic vertebral body fractures: Th8 (3) Th9 (5) Th10 (2) Th11 (3) Th12 (6) L1 (25) L2 (10) L3 (3) L4 (1), were operated on. Fractures were classified according to AO: A1 (34), A2 (3), A3 (18), B2 (3). In radiologic evaluation we take under consideration: wedge angle, local kyphosis Cobb angle and vertebral body height measured in anterior, medial and posterior part in tree parallel lines lead through two pedicles and spinous process. Measurements were taken preoperatively, one month and 6 months postoperatively. In cases of B2 (3) and A3 (1) fracture, transpedicular stabilization was also performed. Whole 58 surgical procedures were facilitated with CT O-arm scan and StealthStation S7 Surgical Navigation System. In clinical evaluation ODI and VAS were measured preoperatively, one month and 6 months postoperatively. Results: We observed VAS reduction (from 7,17 to 2,26) and ODI improvement (from 73,03 to 27,53). In radiological evaluation we achieved height restoration in anterior (3,55 mm), medial (4,23 mm) and posterior (2,45 mm) part of vertebral body that was maintained in 6 months. Wedge angle was reduced for 8,56 degree and local kyphosis Cobb angle for 4,92. Asymptomatic cement leakage was observed in 24 cases. Conclusions: A Procedure lead to significant height restoration combined with good clinical outcome and is maintained in 6 months observation. Procedure may be performed minimally invasive and in some instances can be also combined with percutaneous transpedicular stabilization.

Tumor

P380 - Oblique Sagittal Osteotomy for Treatment of a Giant Cell Tumour

David Pescador¹, Tony Setiobudy², Diego Rendón³, Carlos Marqués¹, Lourdes Ollero⁴, Juan Francisco Blanco¹

¹Spine Unit, Department of Orthopaedics, Complejo Asistencial Universitario de Salamanca, Salamanca - Spain ²Spine Unit, Department of Orthopaedics, Mount Elizabeth Medical Centre, Singapore - Singapore ³Department of Orthopaedics, Hospital Universitario de Canarias, Santa Cruz de Tenerife - Spain ⁴Department of Orthopaedics, Salamanca, Salamanca - Spain

Introduction: Curative resection surgery of spinal tumors usually requires vertebral osteotomies in order to remove the tumor with safety margins. The marrow and neurovascular structures, together with the location, extension and nature of the tumor largely condition the surgical treatment. Giant cell tumors that affect the spine and the thoracic wall are very rare and can reach a large size. From a histological perspective, they are benign lesions, but locally they show an aggressive behavior that destroys and invades neighboring structures. On the other hand, these tumors show a large capacity to recur, which means that the surgical procedure must be implemented via an en bloc resection with safety margins. We present the case of a giant cell tumor of the thoracic wall that invades the thoracic spine, which was treated with oblique osteotomy guided with pedicle needles. Material and Methods: The patient is a 28-year-old man who had been diagnosed and treated when he presented with a giant-cell tumor of the left side of the chest wall which spread to the spine at a thoracic level. He had undergone a thoracotomy with prior embolization of two segmental arteries of T8 and T9 in which the resection of the tumor lesion was not possible. The patient received chemotherapy and radiotherapy, as well as treatment with denosumab for 5 months with no response in terms of a reduction of the volume of the tumor. The CT study revealed the existence of a mass in the left hemitorax which originated on the side and had mediastinal infiltration with postoperative changes in its posterior region. The PET scan shows a left paravertebral hypermetabolic mass (11x4x13 cm). The pathological anatomy of the first operation described a giant-cell tumor. The patient underwent a one-step surgical procedure. The patient was placed in prone position and a middle posterior approach on the thoracic spine was performed, with transpedicular screw fixation on the right side. On the left side, pedicle screws were placed distal and proximal to the lesion, and on the affected vertebras, the common free hand technique for pedicle screws was applied, but instead of screws, 2.5 mm Kirschner wires were inserted up to the anterior part of the vertebral body. The vertebral osteotomy was performed over these needles with an osteotome. The progressive opening of the osteotomy made it possible to cut off the affected roots. The spinal canal was not opened. At this point, the patient was placed in a lateral decubitus and a left thoracotomy was performed over the previous scar, with free excision margins. The affected section of the wall was delimited and osteotomies of the 6th, 7th and 8th ribs were performed, which made it possible to move the tumor mass. The anterior release continued with a dissection of the aorta and a section of the affected pleura. Finally, the osteotomy was completed with a section of the anterior common vertebral ligament, and an en bloc excision of the lesion was performed. Results: After 48 hours the patient could walk and do respiratory exercises. After 72 hours he could use an exercise bike and he continued his respiratory therapy. The results from the anatomical pathology study of the resected piece confirmed the previous diagnosis of giant-cell tumor. The margins of the tumor were disease-free, and an en bloc excision had been performed, although the history of previous surgery does not exclude the possibility of recurrence. Conclusion: We present a patient with a giant-cell tumor which affects the thoracic wall and vertebral structures which are very close to the main vessels. The technique consisted of a one-step surgical approach with several multilevel oblique osteotomies guided with transpedicular needles to expose the tumor mass after a stabilization with transpedicular bars and screws on the dorsolumbar spine. Afterwards, the patient is placed in a left lateral decubitus to perform a thoracotomy, and a costotomy is performed to facilitate the movement of hte tumor mass and to carry out an en bloc resection of its entire contents together with the affected structures. Although the most important objective of the operation is the complete elimination of the tumor, the stabilization and reconstruction of the spine is also an important challenge. The multilevel oblique osteotomy that is performed in order to achieve adequate margins creates a high vertebral instability, because the procedure involves the resection of multiple pedicles and the anterior part of the vertebral body. Giant-cell tumors of the spine represent a great surgical challenge, and a long experience is required in these cases.

P381 - Denosumab: A New Treatment Option for Recurrent Aneurysmal Bone Cyst of the Spine

Ankit Patel¹, Arvind Kulkarni¹

¹Department of Orthopaedics & Spine Surgery, Bombay Hospital, Mumbai - India

Introduction: ABCs are expansile osteolytic lesions that typically contain blood-filled spaces separated by fibrous septa. Standard treatment includes surgical resection or curettage and packing; however, for some spinal lesions, the standard approach is not optimal. One therapeutic strategy is to treat spinal ABC with an agent that targets a pathway that is dysregulated in a disease with similar pathophysiology. The bone destruction in both giant cell tumors of bone and ABCs is mediated by RANK ligand (RANKL) produced by the tumor cells. Denosumab, a human monoclonal antibody to RANKL, is effective in the treatment of giant cell tumors of bone. Material and Methods: We report a case of a large thoracic spine ABC that responded to denosumab. A 14-year-old female developed increasing back pain and paraparesis. Imaging revealed a lytic lesion in the D5 vertebra with no clear solid component and regions where the cortex was difficult to identify. ABC was diagnosed on biopsy. Two surgeries for intralesional excisions were performed and there was a recurrence again with epidural compression after recovery from paraparesis. Denosumab was given using the regimen for giant cell tumors of bone (120 mg sc monthly with a loading dose). Results: The patient’s back pain and neurologic deficit gradually resolved 2 months after initiation of denosumab treatment. MRI scans at 3, 6, 12, 18 months showed complete resolution and no recurrence. Conclusion: We conclude that denosumab can result in symptomatic and radiological improvement in ABC and may be useful in select cases. Long-term results are mandatory to confirm the efficacy of denosumab and to evaluate local recurrence after stopping denosumab.

P382 - Unilateral Approach for Removal of Ependymoma of the Cauda Equina

Stefano Telera¹, Francesco Crispo¹, Carmine Carapella¹, Alfredo Pompili¹, Nicola Gorgoglione², Laura Raus¹

¹Deparment of Neurosurgery, National Cancer Institute “Regina Elena”, Rome - Italy

²Depertment of Neurosurgery, University of Messina, Messina - Italy

Introduction: Spinal intradural tumors are usually removed by uni- or multi-level laminectomy/laminotomy with midline dural incision. Patients’ pain, discomfort, delayed post-operative kyphosis, and spinal instability (6% of the patients) may be minimized by adopting a more conservative unilateral microsurgery, which avoids bilateral damage to muscles and ligamenta and spares the interspinous ligament. Material and Methods: 15 patients with lumbar ependymomas (14 myxopapillary, one metastatic) were operated upon with unilateral laminectomy (June 2005-March 2015). This series included 8 males and 9 females, mean age 42 years (17-74). The extent of the laminectomy was usually kept to one level, having care to remove all the cranial and caudal ligamentum flavum. When necessary, it was extended cranio-caudally for 1.5-2 cm and/or to a second lamina. Careful radioscopic indentification is mandatory. The dura was opened paramedially, the tumor dissected and removed either “en bloc”, when smaller than 2 cm, or piecemeal, after CUSA debulking. Neurophysiologic monitoring was performed routinely. Dural closure was done with 6-0 Prolene stitches. KPS, Dennis Pain Scale, and Mc Cormick Scale were evaluated pre-post operatively and at follow-up. Results: Mean operative time was 160 minutes (range 100-300). No mortality or major neurological complications were observed. The uncomplicated patients were discharged on day 5-7. 5 patients had orthostatic headaches (severe in two cases); one of them presented a CSF leak which resolved with bed rest and a lumbar drainage for 7 days. Median KPS preoperative was 71. The most common symptom in patients affected by lumbar ependymomas was pain 13 cases out of 15 (median 5 Dennis Pain Scale). 3 patients presented a preoperative neurological deficit: McCormick grade 4 for the patient with metastatic ependymoma, grade 2 and 3 respectively, in other two patients. 3 patients with preoperative sphincter dysfunctions improved post-operatively. No worsening of neurological functions were observed post-operatively.

In lumbar ependymomas we did not observed either recurrent tumors or spinal instabilities during follow up. The young patient affected by metastatic ependymoma died three years after surgery for cerebral recurrence of the disease. After one year of follow-up, only two patients complained about pain (Grade 2 Dennis Pain Scale) (p < 0.001). Median KPS was 95 (p < 0.001). (Wilcoxon signed rank test and paired Student T-test) Conclusion: Hospital stay is shortened and stability preserved with an appropriate microsurgical mini-invasive technique. Neurological and oncological results are good. Patient’s post-operative pain and discomfort are reduced. No external bracing is necessary, permitting early rehabilitation, and probably reduction of the overall costs. Based on our experience on schwannomas and meningiomas, the same technique could be proposed for ependymomas.

P383 - Left Lateral Lombotomic Mini-Invasive Pre-Psoas Approach for Lumbar Vertebral Somatectomy/Vertebrectomy in Cancer Patients

Stefano Telera¹, Carmine Carapella¹, Maddalena Giovannetti¹, Francesco Crispo¹, Alfredo Pompili¹, Laura Raus¹

¹Deparment of Neurosurgery, National Cancer Institute “Regina Elena”, Rome - Italy

Introduction: Criteria for somatectomy in patients affected by spinal metastases, should be strict, since this kind of surgery is challenging and has palliative aims. Symptomatic spinal cord compressions and instability with an expected survival of at least 6 months are reasonable indications. When surgery from L2 to L4 is required, combining a left lombotomic pre-psoas lateral approach with a lateral stabilization or a posterior approach, may offer a valid alternative to other surgical techniques. Material and Methods: Between 2012 and 2016 we operated 9 patients. The series included 6 males and 3 females, mean age 55 years (45-66); two patients had MM, two a recurring cordoma, four solid tumors and one a meningioma. All patients presented a Tokuhashi score ≥ 12. In 7 cases the vertebra L3 was involved, in one the L2 and in one, three vertebral bodies were removed. A standard posterior approach in the prone position, with laminectomy, artrectomy, bilateral peduncolectomy and posterior instrumentation, was performed in 4 patients. To complete the 360° stabilization, the patients were then fixed in lateral position. The skin incision was located amid the XIIth rib and the iliac crest performing a careful dissection of the muscle layers, to preserve ileohypogastric and ilioinguinal nerves. Peritoneal cavity was medialized with blunt dissection. The psoas fibers were gently dislocated laterally. The lumbar plexus remained posterior and was usually visualized after removal of the involved vertebral body. An hydraulic expandable cage was inserted after the somatectomy. In five patients the construct was implemented by lateral stabilization, through screws and plates on the level above and below the treated one. Results: No peri-operative complications, neurological worsening or dural leakages were reported in 7 patients. We did not find an increase of haematic loss with this approach, neither of the hospital stay (median 8 days after surgery). In the patient, affected by a L1-L3 recurrent cordoma, in which a complex reconstructive surgery was necessary, a post-operative dural leakage healed with spinal drainage, and a subsidence of the cage after one month, required further surgery. One patients developed an infection of the surgical wound, which required two surgical revisions and a prolonged antibiotic treatment. Pain relief was obtained in all patients, who remained independently ambulatory with a mean follow-up of 17 months. Conclusion: With this approach, i) the lateral incision, is minimal, ii) the psoas muscle is preserved, minimizing the risk of ambulatory impairment, iii) the overall ability to control relevant anatomic structures as the anterior major arteries and veins, the left ureter, the symphatetic ganglia, the dural sac and the lumbar roots, is increased compared to the pure posterior approach, iv) the somatectomy can be combined with a posterior or lateral stabilization. Although it seems a reasonable compromise for L2-L3-L4 metastatic lesions, a longer follow-up and more cases are essential to draw definitive conclusions.

P384 - Langerhans Cell Histiocytosis Causing Multiplex Spinal Tumor-Like Lesions - An Extreme Rare Entity with Challenging Diagnosis and Management

Laszlo Kiss¹, Aron Lazary¹, Peter Pal Varga¹

¹National Center for Spinal Disorders, Budapest - Hungary

Introduction Langerhans cell histiocytosis (LCH) is a clonal neoplastic proliferation of Langerhans cells with unclear etiology. LCH is a rare entity, with 1 per 1,5 million. Mostly it occurs in children and adolescents but in some cases a late onset could be observed. Only 6% of the cases affect the spine, and only one literature report has published its multiplex spinal appearance so far. The multifocal, progressive disease would require early histological diagnosis and oncological treatment to avoid its spreading and systemic, severe consequences. Materials and methods: Case report with four-year follow-up. Results: A young female patient (35y) with no past medical history presented with intermittent costal, back and low back pain. Detailed imaging studies described multiplex, diverse bone lesions in ThVIII, LIV, LV and iliac crest. MRI T2 signal intensity was varied from hypo- to hyperintensity. LIV showed a mixed lesion with contrast enhancement and soft tissue mass in the spinal canal without neurological compression. PET/CT proved a highly increased FDG uptake in more spinal sites (ThII, ThIV, ThVIII, ThIX, LI, LIV, LV) and the iliac crest. Infectious origin was excluded by detailed laboratory check-up. An LIV open biopsy was performed two months after the date of the MRI. Result was negative. Three month later a trocar biopsy was done from the radiologically significant iliac crest lesion but it did not result in any diagnosis. Laboratory tests, endocrinological and hematological detailed examinations showed no metabolic, hormonal or hematological disease. Repeated imaging studies showed a rapid change in the morphology of the bone lesions, but the patient complaints reduced and she refused any further invasive procedures. Two years later, the patient was readmitted into the hospital because of an acute, severe local neck pain without neurological signs. A severe, unstable CVI compression fracture was diagnosed and a CVI corpectomy was performed. The histological diagnosis of the fractured vertebral bone proved Langerhans cell histiocytosis. Oncological treatment (citarabin) was started 4 weeks after the surgery. One year after the surgery, local control and function is excellent, but complete remission has not been reached regarding the activity of the multiplex spinal lesions. Conclusion: Multiplex spinal LCH in adulthood is an extreme rare clinical entity and can cause severe pathological vertebral fractures. Our case report highlights the diagnostic difficulties of this tumor-like lesion. Based on the long-term follow-up of this patient, we can conclude that a very short interval is required between the imaging studies and the biopsy based on them to catch the bone lesion in its histologically positive phase and to start the early, effective oncological treatment.

P385 - Differentiated Surgical Treatment of Craniovertebral Tumors

Roman Khalepa¹

¹Spinal Neurosurgical Department, Federal Center of Neurosurgery, Novosibirsk - Russian Federation

Introduction: The craniovertebral junction is a funnel comprised of the clivus and foramen magnum and the upper two cervical vertebrae that acts as a biomechanical unit. Neoplasms that arise within the craniovertebral junction comprise osseous tumors, extensions from the soft tissue that surround the region and neoplasms of nervous system structures. There are posterior, lateral, anterior approaches to the craniovertebral area for the removal of tumors. The use of these approaches should be differentiate depending on the location of the tumor and its relationships to the spinal cord and blood vessels. Material and Methods: From 2013 till 2017 24 patients (7 male and 17 female) were provided surgical treatment. Average age was 54 years. Assessment of the neurological status was performed by ASIA scale (American Spinal Injury Association) and functional status was performed by McCormick scale. MRI, CT angiography were performed to determine the size, location of tumors and their relationships to the spinal cord and vertebral arteries. To determine the instability, the SINS scale and White-Panjabi criteria were used. Surgery: far lateral approach used for ventral and ventrolateral extramedullary tumors or vertebral tumors 15 (63%), transoral approach used in case of ventral vertebral tumor - 1 (4%), median posterior approach used in cases of intramedullary and extramedullary dorsolateral tumors - 8 (33%). Results: Clinical outcomes were estimated according to McCormic and ASIA scales. Average McCormic before surgery 1.8 ± 0.6, after surgery 1.7 ± 0.8 and in 1.5 year 1.6 ± 0.8. ASIA before surgery E - 8; D - 15; C -1; after surgery E - 6; D - 17; C - 0; B - 1 and in 1.5 year E - 8, D - 15; C - 1; B - 0. Total removal 19 (15 extramedullary tumors, 2 vertebra tumors, 2 intramedullary), subtotal 5 (4 vertebra tumor, 1 extramedullary). Histology: ependymoma -1; cavernous angioma - 1; schwannoma - 7; meningioma - 5; neurofibroma - 4; chondrosarcoma - 1; plasmocytoma - 2; metastasis of adenocarcinoma - 1; chordoma - 1. Complications: Infection of the surgical site - 1 case; pseudomeningocele 2; neurological deterioration – 1. Follow up 1,5 year. 3 patients died: 1 neurofibroma (concomitant pathology, myocardial infarction) in 6 months after surgery; 1 chondrosarcoma, continued growing (refusal to reoperation) in 12 months after surgery; 1 metastasis of adenocarcinoma (progression of the underlying disease) in 6 months after surgery. Conclusion: The differentiated application of various surgical approaches ensures the achievement of good functional results.

P386 - Pathological Fracture of Aggressive Vertebral Hemangioma with Spastic Paralysis

Wendy XP Lee¹, Nur Aida F Senan², Tiam Siong Tan¹, Ying Chyi Chong², Chung Chek Wong²

¹Department of Orthopaedic Surgery, Sibu Hospital, Sarawak, Malaysia, Sibu - Malaysia ²Department of Orthopaedic Surgery, Sarawak General Hospital, Kuching, Malaysia, Kuching - Malaysia

Introduction: Aggressive form of Vertebral Hemangioma (VH) with dissolution and massive collapse of vertebra remains a rare entity against the backdrop of its relatively common dormant asymptomatic counterparts found incidentally on radiological imaging and or autopsies. Neurological deficit may be incurred as a result of extra-osseous extension into the spinal canal compressing onto spinal cord. We present a case of aggressive thoracic VH with vertebral collapse and cord compression. Material and Methods: A 31-year-old female presented at a late setting of one-month in spastic paraplegic state with a preceding ten-month history of back pain and nocturnal accentuation followed by new onset thoracic radiculopathy and progressive bilateral lower weakness after having sustained a trivial fall. Zero motor power with spasticity over bilateral lower extremities (upper motor neuron signs) and discernible sacral and sphincter sparing were demonstrated. Plain radiograph discovered T8 vertebral collapse sparing the subjacent discs with focal protrusion of posterior vertebral body. Magnetic resonance imaging revealed T8 pathological fracture with extra-osseous soft-tissue mass extension causing spinal cord compression with low to isointense on T1-weighted, hyperintense on T2-weighted & increased uptake post contrast-enhancement. Preoperative differential diagnosis erred towards metastatic entity however primary source workup was negative. T8 subtotal resection via pedicle subtraction posterior column closing wedge osteotomy, and posterior T6 to T10 instrumentation was performed. Results: A notably greater-than-usual hypervascular bleeding state was encountered upon T8 vertebral resection and osteotomy. Upon completion of decompression, the cord was noted to recover normal pulsation. Histological examination revealed microscopic bony trabeculae enclosing a fibrous stroma containing multiple dilated blood vessels of varying sizes lined by single layer of benign endothelium, in keeping with VH. Substantial functional recovery was observed since the first week of her postoperative period with subsequent attainment of normal lower limbs neurological examination and independent ambulatory capacity at three-month follow-up. Conclusion: Rare presentation of VH with associated severe fracture collapse and myelopathy, the fourth and last within the spectrum of VH, renders atypical radiological features. To be borne in mind of the underlying pathologically hypervascularity state in its most aggressive form may intelligibly explain its operative mechanism in causing acute cord compression. Also, elucidating the significance of hypervascular stroma in its most aggressive form depicting as hypointense signal intensity in T1-weighted in contrast to its dormant non-aggressive T1 hyperintensity owing to the presence of fatty stroma can aid in delineating the most probable pre-operative diagnosis in retrospect. To be aware of the predictive factors of a potentially aggressive VH transformation based on the presence of three or more of six radiological features, namely, its location between T3-T9, entire vertebral body involvement, neural arch extension, expanded cortex with indistinct margins, irregular honeycomb pattern and presence of soft tissue mass, can raise attention for vigilant follow up. Delayed presentation in a paraplegia state, especially an incomplete one with sacral sparing, shall not hinder surgical dimension in terms of adequate decompression and stabilization due to the optimistic nature of recovery of benign tumor as such.

P387 - Correlation between Clinicopathological Features and Surgical Outcome in Intramedullary Spinal Cord Tumors

Rajesh Kumar Sharma¹, L N Gupta¹, Ajay Choudhary¹, Suryanarayanan Bhaskar¹, Sushil kumar Shinde¹

¹Department of Neurosurgery, PGIMER DR RML Hospital, New Delhi - India

Introduction: Spinal tumors are rare and potentially devastating lesions that threaten the patient’s mobility or even life. Intramedullary tumors are defined as all space occupying lesions localised inside the spinal cord. Intramedullary tumors are rare in all spinal tumors. Both the histologic type and grade is critical in the diagnosis and treatment of spinal cord tumors. Material and Methods: This prospective observational study was conducted in the Department of neurosurgery, PGIMER & Dr. RML Hospital, New Delhi. The study period was 1 year 6 months. Patients were clinically evaluated with modified McCormick scale pre and post-operatively. Total 23 cases were operated and followed post operatively after 1 and 3 months. Results: Postoperatively patients were divided in three groups based on surgical outcome.Astrocytoma was most common tumor followed by ependymoma and hemangioblastoma in our study and significant correlation found between surgical outcome and extent of resection based on histological findings. A statistically significant change in McCormick Grade was observed from pre-operative stage and 3 months post-operative (p = 0.007) which was suggestive of better outcome with early intervention in patients with good preoperative neurological status and better tumor histology. Conclusion: Tumors plane and extent of resection are better predictors for surgical outcome which depends on tumor histology also postoperative neurological outcome is better if preoperative neurological status is good as suggested by modified McCormick grade, hence we conclude and recommend tumor histology and preop McCormick grade as most important determinant of surgical outcome.

P389 - Postoperative Hardware Failure in Patients Undergoing Surgery for Metastatic Spinal Tumors

Vikram Mehta¹, Rachel Pedreira², Nancy Abu-Bonsrah¹, A. Karim Ahmed³, Rafael De la Garza Ramos⁴, C. Rory Goodwin¹, John Berry-Candelario¹, Eric W. Sankey¹, Zachary Pennington³, Ziya L Gokaslan⁵, Justin Sacks², Daniel M. Sciubba³

¹Department of Neurosurgery, Duke University Medical Center, Durham - United States ²Department of Plastic Surgery, The Johns Hopkins School of Medicine, Baltimore - United States ³Department of Neurosurgery, The Johns Hopkins University School of Medicine, Baltimore - United States ⁴Department of Neurological Surgery, Montefiore Medical Center/Albert Einstein College of Medicine, New York, New York, Newy York - United States ⁵Department of Neurosurgery, The Warren Alpert School of Medicine of Brown University, Provodence - United States

Introduction: The spine is the most common site of skeletal metastases, affecting approximately 30% of individuals with cancer. The aim of surgical treatment for metastatic spine disease is generally palliative to address pain and/or neurologic compromise, significantly improving patients’ quality of life. Patients with metastatic spine disease, however, represent a vulnerable cohort and may have comorbidities or previous treatments that impair the structural integrity of spinal hardware. As such, identifying factors that may contribute to hardware failure is an essential component in treating individuals with metastatic spine disease. The aim of this study was to identify pre-operative risk factors associated with hardware failure in patients undergoing surgical treatment for metastatic spine disease Material and Methods: A retrospective cohort study was conducted to include patients surgically treated for metastatic spine tumors between 2003 and 2013, at a single institution. A univariate analysis was initially performed to identify associated factors. Any associated factor with a p-value < 0.20 was included in the multivariate analysis. Results: 3 patients (1.9%), of the 159 patients included in the study, had failure of the spine instrumentation. 1 patient had metastatic prostate cancer, and 2 had metastatic breast cancer. Patient demographics, co-morbidities, tumor location, and primary tumor etiology were not found to be statistically significant, with respect to hardware failure. Predictive factors included in the multivariate model were other bone metastasis, visceral metastasis, brain metastasis, Modified Rankin scale, previous systemic chemotherapy, previous radiation to the spine, and mean survival. Previous radiation to the spine was the only factor to be significantly associated (p = 0.029), present in all three patients with hardware failure. Of note, there was a trend indicating that patients with longer life expectancies were more likely to experience hardware failure (mean survival of 16.7months in non-failure cohort vs. 33months in failure cohort), though this did not achieve statistical significance due to the limited sample size of patients with hardware failure. Conclusion: Hardware failure is a risk for all patients who undergo instrumentation following resection for metastatic spine tumors. This study identified that pre-operative radiation may increase the risk for hardware failure in this population.

P390 - Spinal Metastases in a General Hospital, Los Angeles Chile

Oscar González¹, Catalina González Bustamante², Nicolas Costa Trucco¹, Boris Fuentealba Contreras¹, Luis Medina Barra¹, Patricio Campos Carrasco¹, Tatiana Saavedra Palma¹, Ramon Segovia Mera¹, Gustavo Canessa Aguila¹

¹Complejo Asistencial Victor Rios Ruiz, Los Angeles - Chile ²Universidad San Sebastian, Concepción - Chile

Introduction: Spinal metastases are the most common tumors of the spine, compromising approximately 90% of masses encountered with spinal imaging. Spinal metastases are more commonly found as bone metastasis and approximately 20% present with symptoms of spinal canal invasion and cord compression. The advances in diagnosis and treatment lead to a better survival and prognosis, thus a more complicated management algorithm has devolved requiring a multidisciplinary approach with institutional commitment and support.

we review our experience in a General Hospital in the last seven years. Material and Methods: We reviewed 34 patients hospitalized in our center, admitted to the neurosurgery unit between 2000 and 2016, with spinal metastases. Data was collected from their initial admission and from follow-up and electronics records. Statistic analysis was performed using Microsoft Excel 2010 and STATA v10. Results: Of the total number of patients evaluated, all sustained spinal metastases. Mean age was 64 (SD: 17 - 89) years. 59% were mens (20/34). The initial symptoms were axial pain 65% (22/34), radiculophaty 21% (7/34) and motor deficit 14% (5/34). The most affected segment was thoracic (41%) and lumbar (38%). In this case series the etiology of metastases was multiple myeloma/plasmacytoma (44%), follow by lung cancer, breast cancer, prostate cancer and sarcomas with a 9% each one, kidney and gallbladder cancer with 6% each one. Surgical treatment was required in 68% of cases, the other 32% underwent orthopedic management and/or palliative care. 47% (16/34) has a good outcome. 30 day mortality was 6% (2/34); 6-month mortality was 15% (5/34). Loss of follow -up was 12% (4/34). Conclusion: To optimize the outcomes of patients with spinal metastatic disease, a multidisciplinary approach is necessary. The rol of Surgery is important for biopsy, decompression and stabilization. This case series only represent a small sample of the universe of patients suffering because spinal metastases. Emphasis must be done in the early detection of this condition and related complications, and improve medical therapy and paliative care.

P391 - Paradigm Shift in Sacral Chordoma Treatment: The Combination of Intracapsular Debulking and Carbon Ion Radiotherapy

Zsolt Szövérfi¹, Aron Lazary¹, Peter Pal Varga¹

¹National Center for Spinal Disorders, Budapest - Hungary

Introduction: Sacral chordoma (SC) is a rare primary spinal tumor where the adjuvant treatment possibilities are limited. The gold standard in the treatment of SC is the en bloc resection which is a surgical procedure with significant morbidity, associated with decreased quality of life (QOL). This is enhanced in the case of elderly patients with multiple comorbidities. The objective of this paper is the introduction of a new palliative surgical procedure combined with a novel adjuvant radiotherapy the carbon ion radiotherapy, which can be applied at the elderly patient population. Material and Methods: The surgical procedure relies on the morphologic property of SC of having a jelly content bordered by a pseudocapsule. From a dorsal approach a small 3-4 cm incision is performed above the sacrum, the pseudocapsule is dissected and incised. A suction tube is inserted in the tumor; thus the jelly content can be suctioned out. This can be completed by blunt perforation of the intratumoral septum’s. The obtained cavity is irrigated with a 25% phenol solution. This procedure was named the “intracapsular debulking” technique (ICD). After ICD the patients can be sent to carbon ion radiotherapy, which is preceded by a presacral, pretumoral silicon spacer insertion, to prevent the visceral radiotoxicity. Results: Between 2011 and 2017 ICD was performed at 12 SC patients. The mean age of the patients was 68 years (38-84 years), the female: male ratio was 6:5. The mean OR time was 60 minutes (30-135 minutes), the mean blood loss was 89 ml (50-3000 ml). During postoperative follow up tumor progression was observed at 54% of patients. In consequence, at four patients we performed more than one ICD procedure, in three cases two procedures, in one case four procedures. We observed postoperative complications at five patients: in three cases deep wound infection, in one case superficial infection and in one case transient urinary disfunction. In three cases the ICD procedure was followed by carbon ion radiotherapy, in two cases with presacral silicon spacer implantation. Three patients died during follow up due to tumor progression. The rest of the patients are under oncologic control with minimal complaints and symptoms. Conclusion: Hereby we present a novel surgical technique for palliative treatment of sacral chordoma, which can be applied in elderly patients with multiple comorbidities. In our case series we found that the ICD procedure can slow the tumor progression, and alleviate patient symptoms like pain or vegetative disfunction. Combining ICD with carbon ion radiotherapy can cause even tumor remission and can provide a prolonged survival with good quality of life. Further long term prospective studies are needed to support our findings.

P392 - Global C2 Dumpbell- Shaped Cervical Neurinomas: What is the Best Approach?

Orlando Righesso¹, Daniel Volquind², Marco Antonio Koff², Asdrubal Falavigna²

¹Hospital Tacchini, Bento Gonçalves – Brazil ²University of Caxias do Sul, Rio Grande do Sul - Brazil

Introduction: The treatment of hourglass-shaped neurinomas of the C2 root is surgical, using various approaches such as the posterior, postero-lateral, anterior or combined ones. There are controversies in the literature regarding the choice of the best surgical access aiming to remove the tumor completely and safely and maintaining the stability of the spine. This paper reports the authors’ experience with 14 hourglass-shaped neurinomas of the C2 root, comparing the posterior and anterolateral approaches. Material and Methods: Fourteen patients with hourglass-shaped neurinoma of the cervical root of C2 were surgically treated. The analysis involved symptoms, radiological diagnosis, information about surgery and postoperative outcome. The posterior approach was used to remove the tumors in 9 patients, and the anterolateral one in 5 patients. The 10 steps and tips/tricks for safe surgical removal are identified and reported. Results: Females predominated in this sample (n = 8) and the mean age was 52 ± 4.16 years. The time from onset of the symptoms to diagnosis was 17.8 months ( ± 7.8 months). The mean surgical time was 180 minutes ( ± 39.15) in the posterior approach and 192 minutes ( ± 22.17) in the anterolateral approach (p = 0.52). There was no statistically significant difference in the volume of intrasurgical bleeding among the groups (posterior approach: 70.71 ± 16.93; anterolateral approach: 65.00 ± 24.15; p = 0.64). The tumor was completely resected in all patients. A complication occurred with the posterior access, which was the presence of a cerebrospinal fluid fistula, and it was necessary to reoperate, reconstructing the duramater with fascia lata. Conclusion: The tumor was completely resected with both surgical approaches, but the posterior approach has the advantage of being more familiar to the surgeon.

P393 - Developement and Validation of Clinical Prediction Models of Survival and Clinical Outcomes for Patients with Metastatic Epidural Spinal Disease: A Systematic Review

Anick Nater¹, Jetan Badhiwala², James Hong³, So Kato⁴, Melanie Anderson⁵, Michael Fehlings¹

¹Department of Surgery, University of Toronto, Toronto - Canada ²Division of Neurosurgery, Toronto Western Hospital, Toronto - Canada ³Toronto Western Research Institute, University Health Network, Toronto - Canada ⁴Krembil Research Institute, Toronto Western Hospital, Toronto - Canada ⁵University Health Network, Toronto - Canada

Introduction: In multivariable prognostic research, the development and external validation are the first phases typically involved towards the establishment of clinical prediction models (CPMs) in practice. This systematic review aims to identify and assess CPMs created to predict clinical outcomes in patients with metastatic epidural spinal disease (MESD) and subsequent validation studies. Material and Methods: Three electronic databases were searched (January 1, 1990 to June 20, 2017), without language restriction, to identify studies that developed or evaluated CPMs predicting any clinical outcomes in adult patients with MESD (CRD42017072908). Selected studies were then assessed based on their accordance with the Transparent Reporting of a multivariable prediction model for Individual Prognosis Or Diagnosis (TRIPOD) statement. Results: Among 7,275 unique full-text articles, 107 were included. Among the 41 articles describing the development of a CPM, 25 did not include any assessment of model performance while only 5 specifically mentioned missing data and 13 reported the number of outcome events. We identified 76 studies evaluating CPMs. Among the 25 articles with the term “validation”, “validated” or “validity” in the title or abstract, missing data, number of outcome events as well as both calibration and discrimination were specifically mentioned in 6, 13 and 3 studies, respectively. Conclusion: Since 1990, over 40 CPMs predicting clinical outcomes in patients with MESD were developed and 76 studies performing some sort of evaluation of such CPM were published. Based on the items included in the TRIPOD statement, the majority of these studies did not report on key methodological and data analysis elements. The lack of rigor in the development and validation of CPMs may explain why most CPMs are not generally used in clinical practice.

P395 - Primary Spinal Tumors at the National Medical Center “La Raza” Mexico City: Statistics From July 14, 2014 to July 30, 2017

Jorge Luis Olivares Camacho¹, Jorge Luis Olivares Peña², Jonathan Samuel Morgado Vázquez², Jorge Arturo Santos Franco², Carlos Alberto Espitia³, Angel Hernandez Cruz⁴

¹Service of Neurosurgery of the Hospital of Specialties of the National Medical Center “Siglo XXI”, Mexican Institute of Social Security, Mexico City - Mexico ²Department of Neurosurgery, Mexican National Medical Center “La Raza” IMSS, Mexico City - Mexico ³Medical Tower San Angel Inn, Mexico City - Mexico ⁴General Hospital Balbuena, Mexico City - Mexico

Introduction: Retrospective study to determine the statistics of primary intra-axial and extra-axial spinal tumors, which are treated in a medical center of reference and concentration in Mexico City by the Mexican Social Security Institute by a single physician, determine their age of onset, sex relation, location and type. Material and Methods: A retrospective analysis of records of adult patients between 18 and 84 years of age, with diagnosis of primary spinal tumor, treated surgically open by a single neurosurgeon from July 14, 2014 to July 30, 2017 and with confirmatory diagnosis by tumor pathology. Data were analyzed through measures of central tendency and frequency. Tables and graphs representing the results were made. Inclusion Criteria: Adult patients 18 years of age or older. Patients with primary tumor of the spine Exclusion criteria: Patients younger than 18 years. Patients with tumors of metastatic origin. Results: A total of 24 patients were analyzed in the period described, of which 10 are male, 14 are female. The average age was 50 years, minimum age was 18 years, maximum age 84 years. By type of tumor were 10 meningiomas, 7 schwannomas, 1 chondrosarcoma, 2 chordomas, 2 osteosarcomas, 2 ependymomas. The general location of the tumors was 6 cervical, 2 cervicothoracic, 11 thoracic, 1 thoracolumbar, 3 lumbar, 1 sacro-coccygeal. By type of tumor we found that they were located of the following way:

Meningiomas: 2 cervicothoracic, 8 thoracic

Schwannomas: 1 cervical, 3 thoracic, 3 lumbar

Chondrosarcoma: 1 cervical

Cordomas: 1 cervical, 1 sacro-coccygeal

Osteosarcoma: 2 cervical

Ependymomas: 1 cervical, 1 thoraco-lumbar Conclusion: It was found that tumors in this series were more frequent in women than in men, with an average age of 50 years. Meningiomas were the most frequent tumor, secondarily schwannomas, ependimomas, osteosarcomas, chordomas and chondrosarcomas, successively. The main location was the thoracic spine, followed by the cervical location and thirdly the lumbar spine. This information has great value to create strategies for the management of our patients and is comparable to the current literature.

P396 - A Retrospective Observational Study on the Treatment Outcomes of 17 Patients with Atypical Spinal Meningioma Including Four Cases of Metastatic Meningioma

Kyung Hyun Kim¹, Jeong Yoon Park¹, Sung Uk Kuh¹, Dong Kyu Chin¹, Keun Su Kim¹, Yong Eun Cho¹, Sung Hyun Noh¹

¹Severance Hospital, Seoul - Korea

Introduction: Surgical and clinical outcomes were reviewed to determine the biological behavior and prognostic factors of atypical spinal meningioma. Because of the scarcity of atypical meningioma, there is a lack of research on this type of tumor and malignant transformation. Methods: We retrospectively reviewed the data from all patients on whom we performed spinal cord tumor removal between 1994 and 2016. Seventeen patients were pathologically proved to have atypical meningioma. Surgical extent and disease progression were established by the surgeon according to operative findings, postoperative MRI, and outpatient department (OPD) follow-up. Results: Seventeen patients were included in the analysis, 12 (70%) of whom had tumors in the thoracic region, 4 (24%) of whom had tumors in the cervical region, and 1 (6%) of whom had tumors in the sacral region. Complete resection was achieved in 15 (88%) patients, and subtotal resection was performed in 2 (12%) patients. 4 (24%) patients had metastatic meningioma from brain. Among 4 patients, 3 patients administered radiotherapy after surgery as adjuvant radiotherapy. One patient who underwent surgery for anaplastic meningioma in the brain recurred, and underwent three operations in the spine. The 5- and 10-year overall survival rates were 88.3%, while the 5- and 10-year recurrence-free survival rates were 83% and 52%, respectively. Additionally the mean Ki-67 index differed significantly between patients who did and did not develop recurrence (43% vs. 14%; p = 0.001). Conclusions: Total surgical resection should be considered as a primary treatment modality for individuals with atypical spinal meningioma and if subtotal resection was performed, adjuvant radiotherapy is necessary.

P397 - Asymptomatic Implant/Construct Failure in Metastatic Spine Tumour Surgery: Incidence, Onset, and Underlying Mechanisms

Naresh Kumar¹, Ravish Patel¹, Jonathan Tan¹, Barry Tan¹

¹Department of Orthopaedic Surgery, National University Hospital, Singapore - Singapore

Introduction: There is dearth of literature on asymptomatic implant/construct failure in metastatic spine tumour surgery (MSTS). We aim to study the incidence and onset of asymptomatic implant/construct failure and their underlying mechanisms. Materials and Methods: This is a retrospective study of 288 patients (246 for final analysis) who underwent spinal fixations with or without decompression for metastatic spine disease (MSD) at a single tertiary care institute from 2005-2015. The data collected included patient demographics, oncological, operative and postoperative variables. Operative details included were number of spinal levels instrumented and/or decompressed and types of fixation used. Radiological signs of implant/construct failures were noted from available radiographs at each follow-up visit. Results: Asymptomatic implant/construct failure was observed in 41/246 patients (17%) with 43 events. Of these events, 21% were implant failure while 79% were construct failure. The average onset of asymptomatic failure after surgery was 2 months (1-9 months). Early failures ( < 3 months from surgery) accounted for 79% while late failures ( > 3 months) were observed in 21%. Breast (13/40 = 33%), prostate (7/22 = 32%) and haematological (7/30 = 23%) tumours (p = 0.01) were more likely to fail asymptomatically. There was a trend towards asymptomatic failure in patients with SINS > 7, instrumentation crossing junctional areas and construct length of 6-9 levels, although the associations were not significant. The most common radiologically detectable failure mechanism was angular deformity (increase in kyphosis) in 29 patients followed by screw ploughing and screw loosening in 15 patients each. Conclusions: Asymptomatic failures were radiologically detectable early in a majority of cases. However, these were clinically inconsequential and did not require any special intervention.

P398 - Effects of Primary Tumour Type and Management on Survival and Neurology in Patients with Metastatic Spinal Cord Compression

Sheweidin Aziz¹, Annie Law¹, Wai Weng Yoon¹

¹Trauma and Orthopaedic Department, University Hospitals of Leicester, Leicester - United Kingdom

Introduction: Metastatic spinal cord compression is defined radiographically as an epidural metastatic lesion causing true displacement of the spinal cord from its normal position in the spinal canal (1). Spinal metastasis is common in patients with malignancy. The spine is the third commonest site for metastasis after lung and liver (2). Approximately 70% of cancer patients have metastatic disease at death. The spine is involved in up to 40% of those patients. Spinal cord compression may develop in 5% - 10% of cancer patients and up to 40% of patients with pre-existing non-spinal bone metastasis (2). The management of patients with metastatic spinal cord compression is individualised and can include surgery, radiotherapy and chemotherapy. The role of surgical decompression is expanding as the survival times increase. Materials and Methods: Prospective data collection and analysis over a 3 year period of consecutive patients referred with metastatic spinal cord compression were included (n = 289). Record of surgical intervention, non-surgical management, neurological status and survival were included. The patients were followed up for minimum of 6 months. Results: A total of 289 patients were identified in the study, 60.6% were males (175/289) and 39.4% were females (114/289). A mean age of 66 years (median 68 and range 32-94 years). A large proportion of patients were managed non-operatively representing 74.7% (216/289) with a mean age of 69 years (range 32-94, median 70); operatively managed patient had a mean age of 63 years (range 33-87, median 64). Lung, prostate, myeloma and breast accounted for 63% of all primary tumours (n = 182). Lung, Prostate, Myeloma and Breast primaries represented 18.3%, 24.2%, 8% and 12.5% of all tumours respectively. The overall 90 day survival amongst these patients was 41.5% and 77.3% for non-operatively management and operative management respectively (p < 0.0001). More than 50% of patients with prostate and breast primaries showed improvement in neurology following surgical intervention compared to lung and Myeloma where more improvement was observed with other treatment modalities (radiotherapy). Conclusion: Operative intervention certainly has a role in management of patients with metastatic spinal cord compression, however, the natural history of tumours should be taken into account when deciding whether to intervene surgically or not.

References

1. Metastatic spinal cord compression Nasir A Quraishi consultant spine surgeon 1, Claire Esler consultant oncologist 2 BMJ 2011; 342: d2402 doi: 10.1136/bmj.d2402.

2. Metastatic Spinal Cord Compression. Meic H. Schmidt, MD1, Paul Klimo Jr, MD, MPH1 and Frank D. Vrionis, MD, PhD2. J Natl Compr Canc Netw 2005; 3: 711-719.

P399 - Total En Bloc Spondylectomy of C3

Jan Stulik¹, Petr Nesnidal¹, Michal Barna¹

¹Department of Spinal Surgery, First Faculty of Medicine, Charles University and Teaching Hospital Motol, Prague - Czech Republic

Introduction: Radical resection of a vertebra is reserved only for specific tumors that invade the surrounding tissues and recur when not removed completely. The vertebra may be removed using a piecemeal technique or en bloc, using only two (in thora-columbar spine) or more osteotomies (in cervical spine). We present our technique of en bloc resection of subaxial cervical vertebra for Ewing’s sarcoma of C3, with preservation of all nerve roots and both vertebral arteries. To our knowledge, this surgical technique has not been reported in the English literature. The aim of this study is to describe the new technique of radical resection of subaxial cervical vertebra. Material and Methods: A transoral biopsy of tumor tissue anterior to C2-C3 was performed in 8-year old boy, revealing a diagnosis of Ewing’s sarcoma. The patient was started on neoadjuvant chemotherapy. After 6 chemotherapy cycles with the VIDE regimen, the soft-tissue component completely regressed, with the only a residual deposit in C3 vertebral body. Based on further multi-disciplinary meeting, an en bloc spondylectomy of C3 was recommended, preferably with preservation of nerve roots and vertebral arteries. In August 2014, prior to the planned surgery, we performed another thorough examination of the patient using plain films, CT and MRI. Neither angiography nor embolization was performed. The first stage of the operation consisted of resection of the posterior structures. After 19 days we performed the second stage surgery from an anterior approach with the removal of the anterior and lateral parts of the vertebra. The vertebral body was released and extracted en bloc. In the next step, both vertebral arteries were mobilized and shifted medially and the lateral portions of the transverse processes were released and removed en bloc. The empty space was filled with solid allograft and the C2-C4 levels were bridged by the cervical plate in 2+1+2 configuration. Results: There were no complications during both surgeries. The follow-up CT examination 4 months after the operation revealed a clear bone fusion of C2-C4, both anteriorly between vertebral bodies and posteriorly between the arches. Clinically the patient has reached 8 month follow up and had no complaints, both he and his parents were satisfied. Physiotherapy is proceeding according to plan. The patient remains under supervision at our centre. Conclusion: Total en bloc spondylectomy of a subaxial cervical vertebra with preservation of vertebral arteries and nerve roots is a radical surgery that should be used to treat only the most serious conditions. The risk of neurological deficit is outweighed by the benefits of oncological radicality. This new surgical technique has not yet been described and it is clear, that a larger cohort of patients is necessary to assess and potentially modify this technique so that it can be used more frequently in the future.

P400 - Is Salvaged Blood Transfusion Appropriate in Metastatic Spine Tumour Surgery? A Prospective Clinical Study

Naresh Kumar¹, Jonathan Tan¹, Nivetha Ravikumar¹, Ravish Patel¹, Dhiraj Sonawane¹

¹Department of Orthopaedic Surgery, National University Hospital, Singapore - Singapore

Introduction: Salvaged blood transfusion has not found wide application in MSTS due to the theoretical concern of reinfusing tumour cells resulting in tumour dissemination; despite its routine use in spinal surgeries for degenerative conditions and deformity. We have previously reported our laboratory studies on the safety of the blood salvaged during MSTS. Spine surgeons, however, remain reluctant to employ IOCS because of the lack of clinical data addressing the concerns of tumor dissemination. Materials and Methods: We prospectively analyzed 42 patients who underwent MSTS between January2014 and January2016. Patients were divided into three groups depending on transfusion history: (i) no blood transfusion(NBT) group (ii) salvaged blood transfusion (SBT) group and (iii) allogeneic blood transfusion (ABT) group. Primary outcome measure was progression-free survival (PFS) rates comparing between the three groups. Overall survival (OS), postoperative complication rates and length of hospital stay (LOS) were also studied as secondary outcomes. Results: There was a trend towards better PFS and OS rates in SBT group compared to ABT or NBT group though the differences were not significant. Univariate and multivariate Cox regression analyses revealed that primary tumour type and ECOG performance status were the factors significantly influencing PFS. Transfusion status did not increase the risk of tumour progression. Postoperative complication rates and length of stay were also favourable in SBT group compared to ABT and NBT group. Conclusions: Patients who received salvaged blood transfusion had comparable outcomes in terms of tumour progression and survival to those who received allogeneic blood. Our study paves a path for larger cohort or randomized study where salvaged blood transfusion can be evaluated for its appropriateness and efficacy in patient blood management for oncological surgeries.

P401 - Factors Influencing Extended Hospital Stay in Patients Undergoing Metastatic Spine Tumour Surgery

Naresh Kumar¹, Samuel Wang¹, Ravish Patel¹, Nivetha Ravikumar¹, Jonathan Tan¹

¹Department of Orthopaedic Surgery, National University Hospital, Singapore - Singapore

Introduction: Patients with spinal metastases are elderly, high-risk patients with a shorter predicted survival. Deeper understanding of the factors influencing eLOS in these patients will assist both physicians and patients alike to better weigh the costs and benefits of spinal tumour surgery and aid in making an informed decision regarding admission and discharge as well as preoperative planning of surgical procedure. Extended LOS is well studied for elective surgeries; however, there is paucity of literature regarding LOS in patients undergoing MSTS. Materials and Methods: We included all patients who underwent MSTS at our institution between 2005-2015. Data were retrieved by manually searching the case notes and hospital electronic records which included preoperative, intraoperative and postoperative variables as well as socioeconomic factors. The outcome measure was eLOS that we defined as positive when the LOS exceeded the 75th percentile for this cohort. Univariate and multivariate logistic regression analyses were performed to determine the predictive factors of eLOS. Results: A total of 267 patients were included in the final analysis. The overall median LOS was 10 days (1-30 days) and 27% of patients had extended LOS (LOS ≥ 16 days). Multivariate analysis revealed that significant variables independently associated with extended LOS were Charlson comorbidities index ≥ 8, preoperative haemoglobin level ≥ 12g/dl, 3 or more spinal segmental levels decompressed, presence of postoperative complications, absence of family support and discharge destination being community hospital. Conclusions: The current study provides evidence that there are medical/surgical as well as socioeconomic factors influencing eLOS in patients undergoing MSTS. It will assist the health care providers for better resource allocation as well as enable metastatic spine patients to spend a larger proportion of their limited life span in their home or preferred environment.