Rapid Fire Presentations

RF01: DEGENERATIVE LUMBAR SPINE SURGERY 1

ID: 1960

RF002: Minimally invasive transforaminal lumbar interbody fusion (MIS TLIF) with expandable cages that expand both height and lordosis: a comparison of the one-year postoperative outcomes of two cage designs

Chibuikem Ikwuegbuenyi ¹ , Khanathip Jitpakdee ¹ , Fabian Sommer ¹ , Edna Gouveia ¹ , Minaam Farooq ¹ , Blake Boadi ¹ , Jessica Berger ¹ , Noah Willett ¹ , Ibrahim Hussain ¹ , Roger Härtl ¹

¹ Och Spine at NewYork-Presbyterian/Weill Cornell Medical Center, Department of Neurological Surgery, New York, United States

Introduction: Failure to achieve lordotic alignment is a common challenge following minimally invasive transforaminal lumbar interbody fusion (MIS TLIF), even when using expandable cages that increase disc height. This study examines the impact of two different types of expandable cages in MIS TLIF: one that increases only disc height (Group H) and another that expands both height and lordosis (Group HL). We compared the postoperative sagittal alignment outcomes, clinical results, fusion rates, subsidence, and effectiveness in maintaining sagittal alignment during a one-year follow-up period between these two groups. Material and Methods: Seventy-five patients who underwent MIS TLIF using expandable cages were reviewed. These included 35 cases in group H and 40 cases in group HL. Clinical outcomes, including a visual analog score of back pain (VAS-B), leg pain (VAS-L), and Oswestry Disability Index (ODI), and radiographic parameters, including disc height, segmental, and lumbar lordosis, were evaluated. The fusion status, subsidence, and complications were recorded at each follow-up. Results: Both groups demonstrated significant improvements in VAS-B, VAS-L, and ODI, with no difference between groups. Both group H and group HL showed substantial improvement in pain relief at both the 1-month and 1-year follow-up evaluations, with no significant differences in 1-year postoperative VAS-B (3.8 ± 3.4 and 2.8 ± 2.8, respectively, p = 0.332), VAS-L (2.1 ± 2.4 and 1.7 ± 2.8, respectively, p = 0.591), and ODI (20.6 ± 22.2 and 16.4 ± 19.1, respectively, p = 0.540), indicating comparable clinical outcomes a year after surgery. There was also a significant increase in disc height and foraminal height postoperatively. For sagittal alignment at the 1-year follow-up, group HL showed significantly greater positive changes in segmental lordosis (4.0 ± 3.3° vs 1.9 ± 5.4°, p = 0.045) and disc angle (5.8 ± 4.1° vs 1.9 ± 4.2°, p < 0.001) compared to group H. The overall fusion rate was 92%, and the incidence of subsidence was 32% (decreased to 20% after completing the initial 20 cases as part of the learning phase). No difference was observed between the two groups regarding overall complications, including revision surgeries and neurological deterioration. Conclusion: The study findings indicate that MIS TLIF with expandable cages designed to increase the lordotic angle can achieve favorable clinical and radiographic outcomes, a relatively high fusion rate, and more significant increases in segmental lordosis up to the 1-year follow-up as compared to conventional expandable cages that increase only disc height. Cautious experience utilizing these cages is essential to prevent excessive force in achieving greater disc height or lordosis. This may lead to cage subsidence, pseudarthrosis, and failure to maintain lordotic alignment.

ID: 2239

RF003: The impact of unmet expectations on patient satisfaction in minimally invasive lumbar spine surgery

Kiumars Edalati ¹ , Michael Jeffko ^1,2 , Paul Wilson ¹ , Aiyush Bansal ² , Patricia Lipson ^1,2 , Jack Sedwick ^1,2 , Maxey Cherel ^1,2 , Laura Reynolds ^1,2 , Philip Louie ²

¹ University of Washington, Seattle, United States,

² Virginia Mason Medical Center, Seattle, United States

Introduction: With the increasing prevalence of minimally invasive lumbar surgeries in the United States, identifying key indicators of successful surgical outcomes has become more crucial. This study aims to assess the correlation between discrepancies in patient expectations and outcomes, and overall satisfaction among individuals undergoing minimally invasive lumbar decompression surgery. Additionally, we explore the relationship between other patient-reported outcomes (PROs) and patient satisfaction. Materials and Methods: This prospective cohort study was conducted on patients at Virginia Mason Franciscan Health who underwent elective, minimally invasive one- or two-level lumbar decompression surgeries. The study assessed variables including preoperative and postoperative results from the Musculoskeletal Outcome Data Evaluation and Management System (MODEMS) survey, the Short Form-36 Health Survey (SF-36), and a single-item Likert scale question measuring patient satisfaction. Data from the MODEMS and SF-36 surveys were collected within 10 days preoperatively, and again at 6 weeks and 3 months postoperatively. Patient satisfaction was assessed in relation to their preoperative expectations and postoperative reality using the Likert scale, while health-related quality of life was measured using the SF-36 across eight subcategories. To assess the relationship between expectation-actuality mismatch and patient satisfaction, as well as changes in SF-36 subcategories and patient satisfaction, Spearman’s correlation analysis was performed. Results: Data analysis from 44 patients who completed the 3-month follow-up revealed a significant negative correlation between expectation-actuality mismatch and patient satisfaction (ρ = -0.762, p < .001). Among the 45 patients included, 41 completed the SF-36 at the 3-month postoperative mark. Of the eight SF-36 subcategories, five showed statistically significant correlations between changes in pre- and postoperative scores and patient satisfaction: physical function (ρ = -0.532, p < 0.001), role limitation due to physical health (ρ = -0.366, p < 0.05), energy/fatigue (ρ = -0.399, p < 0.01), social functioning (ρ = -0.491, p < 0.01), and pain (ρ = -0.637, p < 0.001). Conclusion: This study investigates the link between patient expectations and outcomes in minimally invasive lumbar spine surgery. Our results show a strong negative correlation between expectation-actuality mismatch and patient satisfaction, demonstrating that patients whose expectations were not met reported significantly lower satisfaction levels. While this relationship may seem intuitive, it has not been previously demonstrated in the context of minimally invasive lumbar spine surgery. Additionally, significant negative correlations were observed between satisfaction and changes in five of the eight SF-36 subcategories, reinforcing the themes illustrated in our MODEMS survey. These results highlight the importance of aligning preoperative expectations with likely postoperative outcomes to enhance patient satisfaction. By addressing expectation-outcome mismatches, clinicians can potentially reduce dissatisfaction and improve overall recovery experiences following spine surgery.

ID: 588

RF004: Effects of preoperative HbA1c on outcomes following lumbar interbody fusions

Noah Coleman ¹ , Ara Khoylyan ¹ , Matthew Parry ² , Alex Tang ² , Tan Chen ³

¹ Geisinger Commonwealth School of Medicine, Scranton, United States,

² Geisinger Health, Orthopaedic Surgery Northeast Residency, Wilkes-Barre, United States,

³ Geisinger Health, Department of Orthopaedic Surgery, Wilkes-Barre, United States

Introduction: Uncontrolled Diabetes Mellitus (DM) is associated with higher rates of post-operative complications and poor outcomes following spinal surgery. There is limited data describing the long-term outcomes and clinical trajectory amongst post-operative diabetic patients. The purpose of this study was to (1) compare post-operative patient-reported outcome measures (PROMs) between non-diabetic (non-DM) and diabetic (DM) patients undergoing Posterior Lumbar Interbody Fusion (PLIF) or Transforaminal Lumbar Interbody Fusion (TLIF), (2) characterize the clinical trajectory, complications, and rate of improvement between non-DM and DM cohorts, and (3) determine if a clinically relevant HbA1c cutoff exists and if Minimally Invasive Surgery (MIS) protects against values above this cutoff. Material and Methods: Retrospective analysis was performed identifying non-DM and DM patients who underwent elective single or multi-level PLIFs or TLIFs for degenerative pathology between 2019-2023. Diabetes was defined as having a pre-operative HbA1c ≥ 6.5%. Patient demographics, Oswestry Disability Index (ODI), and Patient-Recorded Outcomes Measurement Information System (PROMIS) scores were collected longitudinally. Maximum medical improvement (MMI) was defined as the time point where more than 90% of the cohort achieves minimal clinically important difference (MCID) for both ODI and PROMIS score reports. Descriptive and inferential statistics were performed. Results: A total of 114 non-DM and 14 DM patients were included. The DM cohort was observed to have higher average BMI (non-DM: 30.7, DM: 35.0, p = 0.003), and decreased availability of a care partner (non-DM: 85%, DM: 60%, p = 0.046). No difference was noted for cohort age (non-DM: 55.3 years, DM: 61.3 years, p = 0.097), complications (non-DM: 8%, DM: 0%, p = 0.276), approach (non-DM MIS: 8%, non-DM Open: 92%, DM MIS: 7%, DM Open: 93%, p = 0.921), procedure (non-DM TLIF: 26%, non-DM PLIF: 74%, DM TLIF: 36%, DM PLIF: 64%, p = 0.423), or number of levels fused (non-DM: 1.3, DM: 1.1, p = 0.399). The DM cohort reported poorer pre-operative ODI (non-DM: 45.2, DM: 53.1, p = 0.048), PROMIS-Overall (non-DM: 28.6, DM: 23.7, p = 0.003), PROMIS-Physical (non-DM: 37.5, DM: 33.1, p = 0.004), and PROMIS-Mental (non-DM: 43.7, DM: 38.9, p = 0.022) scores, but were found to have similar clinical improvement exceeding MCID at one year follow up as the non-DM cohort. Both cohorts achieved MMI at similar rates. Multivariate analysis showed pre-operative HbA1c was not correlated with rate of MCID achievement, MMI, or outcome scores when controlling for age, BMI, sex, care partner presence, number of levels fused, procedure type, approach type, and complications. There was no difference in outcomes between MIS or open surgery patients. Conclusion: Elevated pre-operative HbA1c was correlated with worse pre-operative outcome measures. Despite this, both diabetic and non-diabetic patients achieve similar post-operative recoveries following elective PLIF and TLIF with no difference in long term outcomes, complications, and rate of improvement. Our results highlight the importance of continued research on pre-operative optimization, risk management, patient counseling, and developing individualized treatment plans.

ID: 2036

RF005: The impact of BMI on sagittal alignment in patients with degenerative de novo scoliosis

Thilo Khakzad ¹ , Putzier Michael ¹ , Janina Serve ¹ , Nima Taheri ¹ , Julian Vorpahl ² , Athina Danovasili ¹ , Falko Löffler ² , Lukas Schönnagel ¹

¹ Charité Universitätsmedizin Berlin, Orthopädie und Unfallchirurgie, Berlin, Germany,

² RAYLYTIC Software GmbH, Machine Learning Engineer, Leipzig, Germany

Introduction: As obesity prevalence continues to rise globally, its impact on musculoskeletal health becomes a critical area of investigation. Excessive body might also exacerbate spinal deformities, leading to worsened sagittal alignment and subsequently more severe clinical outcomes. Understanding the relationship between body mass index (BMI) and sagittal alignment is essential, as it may reveal significant biomechanical influences that obesity exerts on spinal structure and function. This study aims to quantify the effect of BMI on sagittal alignment in patients with degenerative scoliosis. Materials and Methods: This retrospective study reviewed clinical data from non-operative patients with degenerate scoliosis at the outpatient clinic of a tertiary spine center. Patients with spinal fusion, fractures, spinal metastasis were excluded. Sagittal alignment was measured in EOS imaging with a previously validated machine learning algorithm and included the Sagittal Vertical Axis (SVA), Lumbar Lordosis (LL), Pelvic Tilt (PT), Pelvic Incidence (PI), Sacral Slope (SS). We performed univariable and multivariable logistic regression to evaluate the association between BMI and the sagittal alignment, which was adjusted for potential confounders: age, sex, diabetes mellitus, and intervertebral osteochondrosis. Results: A total of 421 non-operative patients (52.9% female) with a median age of 71 (IQR 61.78) were included in the study. Patients had a mean BMI of 26.5 (IQR 24.30) and a mean SVA of 56.4 mm (IQR 28.9 - 91.3). Univariable regression analysis revealed a significant association between BMI and SVA (β: 2.33, 95% CI: 1.41 - 3.24, p < 0.001), as well as LL (β: 2.33, 95% CI: 1.41 - 3.24, p < 0.001). These associations remained significant in the multivariable analysis, where each unit increase in BMI was linked with a 2.16 mm increase in SVA (β: 2.16, 95% CI: 1.23 - 3.10, p < 0.001) and a decrease of minus 0.36° in LL (β: -0.36, 95% CI: -0.70 - -0.02, p = 0.040). Discussion: The study confirms significant correlation between increased BMI and changes in critical sagittal alignment parameters, highlighting the biomechanical impact of increased body weight on spinal structure. The findings suggest that higher BMI may contribute to worsening sagittal imbalance which may exacerbate symptoms and complicate the management of degenerative scoliosis. These results also highlight the potential benefit of targeted weight management strategies in this patient cohort. By addressing obesity, there may be substantial potential to alleviate the biomechanical burdens on the spine, potentially mitigating symptom progression and improving overall clinical outcomes in this population.

ID: 1783

RF007: Preoperative prognostic factors and models predicting an unfavorable outcome after lumbar discectomy: a systematic review

Annegien Boeykens ^1,2 , Charlotte Kik ¹ , Bart Koes ³ , Clemens Dirven ¹ , Biswadjiet Sanjay Harhangi ^1,2

¹ Erasmus Medical Center, Neurosurgery, Rotterdam, Netherlands,

² Park Medical Center, Neurosurgery, Rotterdam, Netherlands,

³ Erasmus Medical Center, General Practice, Rotterdam, Netherlands

Introduction: Between 10% and 40% of patients experience unfavorable outcomes after lumbar discectomy. Validated prognostic factors or models could help select patients at high risk. With a growing number of national outcome registries, prognostic research has become more feasible. This systematic review aims to identify prognostic factors and models that predict unfavorable outcomes one year after elective lumbar discectomy. Material and Methods: We searched Cochrane, Embase, Medline, and CINAHL from inception to May 14, 2024, and reviewed reference lists of relevant articles. We considered studies involving adults undergoing elective, primary lumbar discectomy. We included (preoperative) prognostic factors and model studies with prospective cohort designs and one-year follow-up. We included studies reporting unfavorable outcomes (e.g. non-success, poor or worse outcomes) in disability, pain, functionality, or quality of life. Only predefined patient reported outcome measures were acceptable. We excluded studies lacking MRI diagnostics or involving other spine disorders (i.e. stenosis, listhesis, trauma, malignancy, and malformation). Two reviewers independently selected studies, extracted data (CHARMS), assessed the risk of bias (QUIPS or PROBAST), and evaluated the certainty of evidence (GRADE). We reported the results in accordance with the TRIPOD guidelines. Results: Out of 2,061 articles, fifteen met the inclusion criteria. We identified nine prognostic factors from twelve studies. These factors predicted unfavorable recovery in disability with moderate to high certainty. The Oswestry Disability Index (ODI) was the primary measure of choice. High comorbidity (3 studies, n = 21,363) was the strongest prognostic factor. Moderate evidence associated older age (3 studies, n = 21,363), female gender (4 studies, n = 21,418), smoking (2 studies, n = 10,309), and high BMI (4 studies, n = 21798) to an unfavorable prognosis. The baseline presence of back pain (1 study, n = 11,081), and anxiety or depression (2 studies, n = 14,895) could predict with moderate strength. Also long duration of symptoms, with leg pain > 3 months (1 study, n = 6,468) and back pain > 12 months (1 study, n = 11,081), moderately predicted worse or poor disability post-surgery. This review included prognostic models from Switzerland (n = 1,244), the Netherlands (n = 479), Denmark (n = 1,988), and two from Norway (n = 11,081 and n = 21,161). Four models showed low certainty of evidence due to limited validation and performance issues. One validated machine learning tool from Norway showed strong performance, with a calibration slope close to one. The C-statistic for this ODI model ranged from 0.81 to 0.84 (pooled estimate: 0.82; 95% CI, 0.81-0.84). Conclusion: The baseline presence of anxiety, depression or back pain may help predict an unfavorable outcome one year after lumbar discectomy. Our findings also confirm the prognostic value of age, female gender, smoking, high BMI, high comorbidity, and long duration of symptoms. One machine learning tool showed strong performance. However, most developed models lack validation and accuracy, limiting their clinical applicability.

ID: 1376

RF008: Impact of sarcopenia on outcomes following lumbar spine surgery for degenerative disease: an updated systematic review and meta-analysis

Michael Jian-Wen Chen ¹ , Yuan-Shun Lo ² , Hsien-Te Chen ¹

¹ China Medical University Hospital, Orthopedics, Spine Center, Taichung, Taiwan,

² China Medical University Beigang Hospital, Yunlin, Taiwan

Introduction: In lumbar spine surgery for degenerative disc disease, the negative impact of pre-existing sarcopenia on postoperative outcomes has been noted, necessitating further investigations. This study aimed to consolidate the evidence regarding the prognostic influence of sarcopenia in degenerative lumbar spine surgeries. Material and Methods: A literature search of public databases was conducted up to Nov 15, 2023 using combinations of the key words“sarcopenia” and “lumbar spine surgery”. Eligible studies were those that focused on adults undergoing decompression or fusion surgery for degenerative lumbar spine diseases, and compared the outcomes between patients with and without preoperative sarcopenia. Primary outcomes were change in Oswestry Disability Index (ODI), and back and leg pain visual analog scale (VAS) pain scores. Secondary outcomes were changes in EuroQol 5-Dimension (EQ5D), Japanese Orthopaedic Association (JOA), and Short Form Health Survey-Physical (SFHS-p) scores, and length of hospital stay (LOS). Results: Ultimately, nine retrospective studies with a total of 993 patients were included. Sarcopenic patients exhibited significantly worse functional improvement as assessed by ODI compared to non-sarcopenic patients (pooled standardized mean difference [pSMD] = 0.53, 95% confidence interval [CI]: 0.17-0.90). Back pain (pSMD = 0.31, 95% CI:0.15 - 0.47) and leg pain (pSMD = 0.21, 95% CI:0.02 - 0.39) improvement were also less in sarcopenic patients. Non-sarcopenic patients had greater improvements in EQ5D (pSMD = 0.25) and SFHS-p (pSMD = 0.39), and shorter LOS (pSMD = 0.62). Conclusion: As compared to patients without sarcopenia, those with sarcopenia undergoing lumbar spine surgery for degenerative diseases have lower improvements in functional ability, quality of life, physical health, pain relief and extended hospitalization compared to those without sarcopenia.

ID: 1461

RF009: A decade later: long-term outcomes of disc degeneration surgery in adolescents

Samir Dalvie ¹ , Taarini Johri ¹ , Naveen Ramesh ¹

¹ P.D. Hinduja Hospital and MRC, Spine Surgery, Mumbai, India

Introduction: Despite numerous clinical series, the long-term outcomes of discectomy in adolescents remain uncertain. This study aimed to evaluate the long-term results of discectomy in patients younger than 18 years of age. Material and Methods: A retrospective analysis of 20 adolescent patients who underwent microdiscectomy for prolapsed intervertebral disc between 2009 and 2014 was done. All patients were operated by a single surgeon at a single centre. Pre operative function (VAS & ODI), radiology and neurology were retrieved from the from Electronic Medical Record system and imaging database. The patients were called for yearly follow up and post operative functions (VAS & ODI) were noted. At the recent follow up spinopelvic parameters were assessed to look for any PI-LL mismatch and post laminotomy kyphosis. Complications if any were note. Results: 14 patients were male and 6 were female. L4/5 was the commonest level of herniation followed by L5/S1. Average follow-up of these patients was 10 years. At follow-up, 20 out of 20 patients reported excellent early outcomes. 1 presented with recurrence after 2 years and underwent microdiscectomy. At recent follow up all patients had significant improvement in VAS and ODI scores. Spinopelvic parameters were assessed and were found to be optimal. Conclusion: Microdiscectomy can provide satisfactory clinical outcomes in young patients with disc herniation. Excellent functional and radiological outcomes suggest that surgical management of adolescent disc herniation should be approached where indicated.

ID: 1253

RF010: Qualitative evaluation of paraspinal musculature after minimally invasive lumbar descompression: a prospective study

Ramon Soares ¹ , Nelson Astur ^1,2 , Lucas Silveira Rabello de Oliveira ^1,3 , Michel Kanas ^1,2 , Marcelo Wajchenberg ^1,2 , Delio E. Martins ^1,2

¹ Hospital Israelita Albert Einstein, Orthopaedic and Trauma Department, São Paulo,

² Instituto Cohen Ortopedia, Spine Surgery Department, São Paulo,

³ Faculdade de Medicina do ABC, Orthopaedic and Trauma Department, São Paulo

Introduction: Traditional microdiscectomy methods can cause significant muscle damage, leading to atrophy and reduced biomechanical function, which can negatively impact long-term outcomes, such as persistent lumbar pain. Minimally invasive techniques, such as tubular microdiscectomy, aim to reduce this damage by limiting muscle retraction, offering potential clinical benefits such as reduced blood loss, shorter recovery times, and less postoperative pain. The objective of this study was to quantify fatty infiltration and degree of paraspinal muscle degeneration in patients submitted to tubular microdiscectomy and conventional open microdiscectomy. Material and Methods: A prospective cohort of patients was submitted to microdiscectomy for lumbar disc herniation after failure of conservative treatment. Selection of the technique was based on the surgeon’s preference. Analysis of the multifidus muscle was performed using the Goutallier system and the percentage of fat in the muscle. Preoperative and 1- year postoperative T2- weighted magnetic resonance imaging was used, and statistical analysis was carried out using the Wilcoxon test and Spearman correlation test using a significance level of 5%. Results: Thirty- two patients were included in the study. The percentage of fatty infiltration in the muscle increased on both sides of the spine 1 year after surgery, although only the ipsilateral side presented statistical significance in patients submitted to conventional microdiscectomy (43.3% preoperative and 57.8% postoperative). Muscular degeneration increased significantly ipsilateral to the disc herniation according to the Goutallier classification (grades 1.2) for both interventions. No statistically significant difference was found for fatty infiltration scores or for the degree of muscular degeneration of the multifidus in the comparative analysis of the methods. Conclusion: Muscular damage resulting from surgery of lumbar disc herniation significantly increases fatty infiltration and degeneration of the multifidus. Muscular degeneration was associated with worsening back pain.

Clinical Relevance: While no significant difference was found between the techniques, the tubular minimally invasive approach shows a tendency for less muscle damage. These findings highlight the importance of minimizing muscle injury during surgery to improve postoperative recovery and long- term outcomes.

ID: 510

RF011: Meta-analysis of the effects of diabetes mellitus on fusion rates and patient-related outcomes in spinal fusion surgery

John O'Toole ¹ , Gonzalo Mariscal ² , Christopher Chaput ³ , Michael Steinmetz ⁴ , Paul Arnold ⁵ , Christopher Witiw ⁶ , Bradley Jacobs ⁷ , James Harrop ⁸

¹ Rush University Medical Center, Chicago, United States,

² Institute for Research on Musculoskeletal Disorders, Valencia Catholic University, Valencia, Spain,

³ UT Health San Antonio, Department of Orthopedics, San Antonio, United States,

⁴ Cleveland Clinic Lerner College of Medicine, Neurological Institute, Department of Neurosurgery, Cleveland, United States,

⁵ Loyola University Chicago, Department of Neurological Surgery, Chicago, United States,

⁶ University of Toronto, Department of Surgery, Division of Neurosurgery, Toronto, Canada,

⁷ University of Calgary, Department of Clinical Neurosciences, Calgary Spine Program, Calgary, Canada,

⁸ Thomas Jefferson University, Department of Neurological Surgical, Department of Orthopedic Surgery, Philadelphia, United States

Introduction: Diabetes Mellitus (DM) is believed to be associated with an increased risk of adverse events during spinal surgery. With the increasing prevalence of DM and the increasing number of degenerative spinal procedures, understanding postsurgical expectations and optimal care is essential. This meta-analysis aimed to provide a comprehensive evaluation of the impact of DM on spinal surgery outcomes, specifically assessing fusion rates and patient-reported outcome measures (PROMs). Material and Methods: Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, a systematic search was conducted across PubMed, EMBASE, Scopus, and the Cochrane Library, selecting studies comparing patients with and without DM who underwent spine fusion surgeries. Outcomes of interest were the incidence of spinal pseudoarthrosis and patient-reported outcomes measures (PROMs). Odds ratios (OR) were calculated for dichotomous variables, whereas mean differences (MD) were calculated for continuous variables. Standard Mean Differences (SMD) were use for continuous variables that did not share the same scale or units. Meta-analysis was performed using the Cochrane’s RevMan version 5.4 software. Random effects were used if there was evidence of heterogeneity. Results: Eighteen studies, comprising 118,617 patients, were included in the final analysis. DM patients had a higher incidence of pseudoarthrosis at the lumbar spine (OR 1.13, 95% CI 1.02 to 1.25, p < 0.05). Patients with DM also reported increased VAS back/neck pain scores (SMD 0.21, 95% CI 0.14 to 0.28, p < 0.001) and worse Oswestry Disability Index outcomes (MD 3.96, 95% CI 3.10 to 4.82, p < 0.001). EQ-5D (MD -0.06, 95% CI -0.08 to -0.03, p < 0.001) and SF-12/36 PCS scores (SMD -2.70, 95% CI -4.99 to -0.41, p < 0.05). Conclusion: Patients with DM who underwent spinal surgery had a higher incidence of pseudoarthrosis and worse functional outcomes compared to non-DM patients. These findings underscore the need for targeted clinical management and preventive strategies for patients with DM undergoing these procedures.

ID: 717

RF012: Stand alone cages via lateral or oblique lumbar approaches versus posterior lumbar interbody fusions for adjacent segment disease: a systematic review and meta analysis

Shashwat Shah ¹ , Esteban Quiceno Restrepo ² , Mohamed Soliman ² , Asham Khan ² , Isabelle Stockman ¹ , Joseph St. Onge ¹ , Benard Okai ¹ , Hendrick Francois ¹ , Deanna Chan ¹ , Jeffrey Mullin ² , John Pollina ²

¹ Jacobs School of Medicine and Biomedical Sciences, Neurosurgery, Buffalo, United States,

² University at Buffalo Neurosurgery, Neurosurgery, Buffalo, United States

Introduction: Adjacent segment disease (ASD) is a frequent occurrence following lumbar fusions, with reported incidence rates as high as 40%, leading to substantial rates of reintervention and imposing significant costs on healthcare systems. Various surgical approaches have been employed to manage patients with ASD, including the posterior approach, which offers benefits such as direct decompression but also presents challenges such as dealing with surgical scarring and the risk of cerebrospinal fluid leaks. The utilization of standalone cages has emerged as a pivotal surgical strategy in addressing ASD. The objective of this study was to compare the clinical and surgical outcomes of patients with ASD who underwent management with standalone cages versus posterior approaches (transforaminal or posterior lumbar interbody fusion, TLIF/PLIF). Material and Methods: A systematic review was conducted following the PRISMA guidelines. PubMed and Embase databases were searched using terms such as ALIF, LLIF, OLIF, TLIF, PLIF, and ASD. Out of 811 articles screened, 8 studies met the inclusion criteria. Both dichotomous and continuous outcomes were analyzed using RevMan 5.0. A fixed-effects model was employed when I2 was below 50%, and a random-effects model was utilized in instances of high heterogeneity. Results: Results indicated significantly lower blood loss (-311.66 ml, p < 0.001), shorter operative time (-85.14 minutes, p < 0.001), and reduced length of hospital stay (-3.23 days, p < 0.001) in the standalone cage group. Additionally, the standalone group demonstrated significantly higher disc height change (1.67, p = 0.001) and lower complication rates (OR = 0.38, p = 0.02). However, the standalone group exhibited a higher rate of subsidence (OR = 4.65, p = 0.02) during follow-up. Notably, there were no significant differences in changes in lumbar lordosis, segmental lordosis, or Oswestry Disability Index. Moreover, there were no disparities in reoperation rates or pain outcomes. Conclusion: Standalone lateral cages represent a viable option for treating patients with ASD, demonstrating comparable rates of patient-reported outcomes with fewer complications than TLIF/PLIF. However, patients should be informed about the elevated risk of subsidence.

ID: 2147

RF013: 10-year trend of lateral lumbar interbody fusion in a high-volume academic center: impact of 3D-printed titanium cages on standalone utilization

Marco Burkhard ¹ , Ali Guven ¹ , Paul Koehli ¹ , Jan Hambrecht ¹ , Bruno Verna ¹ , Erika Chiapparelli ¹ , Jennifer Shue ¹ , Federico Girardi ¹ , Andrew Sama ¹ , Frank Cammisa ¹ , Alexander Hughes ¹

¹ Hospital for Special Surgery, New York, United States

Introduction: Lateral lumbar interbody fusion (LLIF) has been used both as a standalone technique and with posterior instrumentation since the early 2000s. While standalone LLIF offers benefits like reduced invasiveness and muscle preservation, concerns over instability, increased cage subsidence, and lower fusion rates have led many institutions to favor routine posterior augmentation. However, in 2017, a 3D-printed Titanium (3DTi) cage was introduced, demonstrating reduced subsidence and improved fusion rates compared to polyetheretherketone (PEEK), potentially expanding the indications for standalone LLIF. This study aims to investigate single institutional trends in circumferential and standalone LLIF usage before and after 3DTi implementation, with secondary outcomes being standalone use in the setting of prior lumbar fusion. Material and Methods: We retrospectively reviewed all LLIF procedures performed by four senior surgeons at a high-volume academic center from January 2014 to December 2023. We assessed the total number of LLIF procedures per year, the proportion of standalone LLIFs, and the use of PEEK versus 3DTi cages. A regression analysis with an interaction term was used to examine whether the trend in standalone use differed before and after the 3DTi transition (2017.2018). The rates of standalone LLIF among surgeons who adopted 3DTi versus those who continued with PEEK were compared between the pre- (2014.2017) and post-transition periods (2019.2023) using chi-square tests. Rates of prior lumbar fusion in patients treated with standalone LLIF were also analyzed using regression analysis. Statistical significance was set at p < 0.05. Results: In total 1864 patients (3259 levels) were included for analysis, with 42.6% (794 patients; 1354 levels) undergoing standalone procedures. Annual LLIF patient volumes ranged from 120 to 228, with a decline during the global pandemic. Three of the four surgeons started to use 3DTi cages in 2017-18, and by 2019 had fully transitioned to their use, while one continued using PEEK. Among those who adopted 3DTi, the rate of standalone LLIFs was significantly higher in the post-transition period (50.7% from 2019.2023) compared to pre-transition (32.3% from 2014.2017; p < 0.001), with no significant change observed for the surgeon who continued with PEEK. Before 3DTi implementation, standalone LLIF use declined from 38-45% in 2014-2015 to 19% in 2017 and remained stable at 19-25% until 2019. From 2019 to 2023, standalone use increased significantly up to 67% in 2023 among surgeons who adopted 3DTi (all p < 0.001), while a non-significant downward trend was seen in the surgeon who continued with PEEK. The rate of prior lumbar fusion before standalone LLIF increased significantly from 26% in 2019 and 20% in 2020 to 40-41% in 2021-2023 (p = 0.043). Conclusion: This study, the largest single-center study to date evaluating standalone and circumferential LLIF procedures, shows a significant increase in standalone LLIF use following the adoption of 3DTi cages. The improved biomechanical properties of these cages may expand the patient population benefiting from this less invasive approach, including those with a prior lumbar fusion. Re-evaluation of standalone versus circumferential LLIF performance and updated guidelines on their use are warranted.

ID: 1945

RF014: Facet joint anatomy and potential degenerative instability at L4-5

Maxey Cherel ^1,2 , Aiyush Bansal ² , Takeshi Fujii ^2,3 , Jack Sedwick ^1,2 , Laura Reynolds ^1,2 , Michael Jeffko ^1,2 , Patricia Lipson ^1,2 , Rafael Garcia de Oliveira ² , Venu Nemani ² , Jean Christophe Leveque ² , Philip Louie ²

¹ University of Washington, Seattle, United States,

² Virginia Mason Medical Center, Seattle, United States,

³ Keio University, Tokyo, Japan

Introduction: The purpose of this study was to identify anatomical features of facet joint degeneration on supine MRI that can predict the level of instability as shown on standing XRs/CTs and to assess their relative associations with indicators of instability on standing imaging. Materials and Methods: A total of 231 cases with operations at L4-5 were analyzed, including 100 cases with spondylolisthesis, 80 with fusions, 149 with decompression, and 54 with discectomy. The mean age of the patients was 64.3 ± 12.6 years, with a mean BMI of 29.0 ± 5.9 kg/m². The cohort consisted of 55 females (23.8%). Preoperative features of facet joint anatomy were measured using radiographic measurements on MRI and X-ray. Multivariate stepwise regression was performed to predict measures of spinal instability. The outcomes measured were the change in % L4-5 slip between standing (XR) and supine (MRI), change between flexion and extension (XR), change in translation between standing (XR) and supine (MRI), and change in L4-5 disc angle between standing (XR) and supine (MRI). Univariate Pearson correlation was performed for the strongest predictors. Results: Multivariate analysis revealed that anterior disc height was a significant predictor of % L4-5 slip change between supine (MRI) and standing (XR) (β = -0.33, p = 0.01), and middle disc height predicted change in L4-5 disc angle (β = -1.17, p = 0.01). Additionally, facet effusion width significantly predicted change in L4-5 disc angle between flexion and extension (XR) (β = 0.32, p = 0.05). Univariate analysis also showed that anterior disc height was significantly correlated with preoperative L4-5 slip (r = -0.51, p < .001). Conclusions: Greater anterior and middle disc heights are associated with improved stability at the L4-5 level. Univariate analysis demonstrated that anterior disc height is strongly correlated with reduced preoperative L4-5 slip, emphasizing its potential role as a predictive marker. Facet effusion width may also be a relevant predictor of instability during motion. These findings highlight the importance of specific anatomical features in predicting spinal stability, informing surgical decision-making between fusion and decompression operations. Further research is warranted to explore additional factors influencing spinal stability.

ID: 1231

RF015: Comparative efficacy of uniportal and biportal endoscopic techniques in the treatment of lumbar spinal stenosis: a meta-analysis

Ramon Guerra Barbosa ¹ , Yan Silva ² , Marcus Vinícius Serra ³

¹ Hôpital de Chicoutimi, Neurosurgery, Saguenay, Canada,

² Hospital São Rafael, Orthopedics, Salvador, Brazil,

³ BESSC, Neurosurgery, Santos, Brazil

Introduction: Endoscopic spine surgery has been increasingly consolidated as a minimally invasive technique for decompressing lumbar spinal stenosis (LSS). However, there remains uncertainty regarding which of the two techniques -uniportal or biportal endoscopy - yields superior outcomes in treating LSS. This meta-analysis aimed to compare the results of these two approaches to provide clearer evidence on their relative efficacy and safety. Material and Methods: A comprehensive search was conducted in the PubMed and Cochrane databases using the MeSH terms “laminectomy” and “endoscopy.” A total of 217 articles were initially identified. After removing 24 duplicates, 193 articles were further screened. Of these, 66 were excluded for lack of relevance to the topic. Finally, only 2 studies met the inclusion criteria by directly comparing uniportal and biportal endoscopic approaches for LSS. Statistical analysis was performed using the Cochrane RevMan software. Results: The two studies included a total of 174 patients. Both approaches demonstrated significant clinical improvements postoperatively, with reductions in Visual Analog Scale (VAS) scores and Oswestry Disability Index (ODI) scores. Biportal endoscopy was associated with a shorter operative time, while uniportal endoscopy was associated with shorter hospitalization time. Blood loss, as well as VAS scores for back and leg pain and ODI scores, were similar between the two techniques. Conclusion: Both uniportal and biportal endoscopic techniques offer effective decompression for LSS, with similar clinical outcomes. Operative time and complication rates were lower in the biportal group, but these differences were not statistically significant. Further research is needed to substantiate these findings and aid in surgical decision-making for the treatment of LSS.

ID: 1983

RF016: Complication rates following lumbar uniportal endoscopic spine surgery (UESS): a systematic review and proportional meta-analysis

Sean Inzerillo ¹ , Chibuikem Ikwuegbuenyi ² , Eesha Gurav ³ , Noah Willett ² , Mousa Hamad ² , Galal Elsayed ² , Osama Kashlan ² , Roger Härtl ²

¹ SUNY Downstate Health Sciences University, New York, United States,

² Och Spine at NewYork-Presbyterian/Weill Cornell Medical Center, Department of Neurological Surgery, New York, United States,

³ University of South Carolina, Columbia, United States

Introduction: Uniportal Endoscopic Spine Surgery (UESS) has emerged as an effective technique for addressing various spinal pathologies, offering reduced tissue damage, shorter recovery times, and improved patient outcomes. However, its considerable learning curve may influence complication rates. Complication rates for UESS have been observed to range from 0-30% in the literature, emphasizing the need for a pooled analysis. We conducted a systematic review and proportional meta-analysis of all studies published in the last decade to quantify the incidence of total and specific complications associated with uniportal lumbar MISS. Material and Methods: We registered on PROSPERO (CRD42024570377) and conducted a systematic search of PubMed, Medline, Embase (via OVID), and the Cochrane Library (Jan 2013.Mar 2024) following PRISMA guidelines. Search terms included “Minimally invasive,” “MISS,” “uniportal,” “lumbar,” “spine,” and “complications.” Studies were included if they involved at least ten adult patients, focused on UESS, and provided extractable data on complication rates. Conference abstracts, reviews, meta-analyses, non-English studies, and those utilizing micro endoscopic, lateral, or oblique surgical approaches were excluded. A random-effects model pooled complication rates and accounted for variability across studies. The Cochrane Risk of Bias Tool and the Newcastle-Ottawa Scale were used for the quality assessment of randomized and non-randomized studies, respectively. All analyses were conducted using the meta package in R Studio. Results: The meta-analysis included 21 studies with 1,258 patients: 14 retrospective or case-control studies, six prospective cohort studies, and one randomized controlled trial. Most studies were high quality, with only one showing moderate risk of bias. Patient ages ranged from 41.6 to 73.5 years, and 38.7% were male. UESS was primarily used for lumbar spinal stenosis, with 15 studies on this condition, and follow-up periods ranged from 6 to 26.5 months. The overall pooled complication rate for UESS was 9.79% (95% CI [7.00%, 13.53%]). Specific complications reported included dural tears (3.75%, 95% CI [2.74%, 5.11%]) in 17 studies, nerve palsy (2.69%, 95% CI [1.06%, 6.66%]) in 14 studies, postoperative hematomas (0.24%, 95% CI [0.02%, 2.59%]) in 8 studies, surgical site infections (0.01%, 95% CI [0.00%, 0.89%]) in 10 studies, and surgical revisions (2.39%, 95% CI [1.06%, 5.29%]) in 11 studies. Total complication rates showed significant heterogeneity (I² = 65.5%, p < 0.01), while specific complications exhibited low to moderate heterogeneity. Conclusion: This proportional meta-analysis of studies from the last decade shows UESS has an overall pooled complication rate of 9.79%, with dural tears and nerve palsy being the most common. These findings support the safety of uniportal approaches for lumbar pathologies, particularly spinal stenosis. However, the variability in complication rates across studies underscores the need for careful patient selection and refined surgical techniques to minimize risks. Future research should focus on identifying predictors of specific complications and comparing long-term outcomes with traditional methods to optimize UESS in contemporary minimally invasive spine surgery.

ID: 2250

RF017: Expectation vs. reality: exploring decisional regret in minimally invasive lumbar spine surgery

Michael Jeffko ^1,2 , Aiyush Bansal ¹ , Patricia Lipson ^1,2 , Jack Sedwick ^1,2 , Maxey Cherel ^1,2 , Laura Reynolds ^1,2 , Philip Louie ¹

¹ Virginia Mason Medical Center, Seattle, United States,

² University of Washington, Seattle, United States

Introduction: Decisional regret is an emerging patient reported outcome (PRO) used to evaluate surgical success and quality patient care. The purpose of this study is to determine if there is a correlation between patient expectation-actuality differences and decisional regret among patients undergoing minimally invasive decompression lumbar spine surgery. Further, we aim to identify if there are other PROs that correlate with patient decisional regret. Materials and Methods: This prospective cohort study gathered data from eligible patients at Virginia Mason Franciscan Health who underwent elective minimally invasive one and two-level lumbar decompression surgery. Variables evaluated include pre and postoperative Musculoskeletal Outcome Data Evaluation and Management System (MODEMS) survey, the Decisional Regret Scale (DRS), and Question 22 of SRS-22. MODEMS survey results were collected 10 days or less preoperatively and 3 and 6 months postoperatively. The DRS was collected 3 months and 6 months postoperatively. Statistical analysis was performed using Spearman’s rank correlation to assess the relationships between patient satisfaction, decisional regret, and expectation-actuality mismatch. Spearman’s rho (ρ) was used to determine the strength and direction of these associations, with statistical significance set at p < 0.05. Correlations were assessed at both 3-month and 6-month postoperative time points to evaluate changes over time in the relationships between these variables. Results: Analysis of initial data from 17 patients who have passed both the 3-month and 6-month postoperative mark demonstrate there is a significant negative correlation between decisional regret and satisfaction at 3 months (ρ = -0.757, p < 0.01) and a moderate negative correlation at 6 months (ρ = -0.618, p < 0.01). The greater the decisional regret a minimally invasive lumbar decompression patient has, the less satisfaction they experience. While this is generally intuitive, it has not been illustrated in a cohort of minimally invasive lumbar patients. Of the 17 patients that have completed both time requirements, there is a moderate positive correlation between decisional regret and expectation-actuality mismatch at 3 and 6 months (ρ = 0.460, p < 0.063) and (ρ = 0.549, p < 0.05). In addition to the 17 patients who completed both the 3-month and 6-month postoperative decisional regret surveys, 33 and 34 patients completed the 3-month and 6-month postoperative decisional regret surveys, respectively. In both cohorts, there was a significant moderate correlation between decisional regret and expectation-actuality mismatch (ρ = 0.431, p < 0.05) and (ρ = 0.602, p < 0.001). Conclusion: This study explored the link between patient expectations, satisfaction, and decisional regret following minimally invasive spinal surgery. Preliminary findings from 40 patients revealed a significant correlation between decisional regret, satisfaction and expectation-outcome mismatch. While greater decisional regret generally correlates with lower patient satisfaction, the relationship between expectation-actuality mismatch and decisional regret is more complex. This study highlights the importance of clear preoperative expectations to better align expectations, enhance satisfaction, and improve recovery outcomes. Open discussions can refine patient preferences, boost satisfaction, and accelerate recovery.

ID: 2690

RF018: Extraforaminal full-endoscopic approach to the L5 pars for L5 - S1 foraminal pathology: technical note and early clinical results

Cristian Ricardo Correa Valencia ¹ , Matias Nahuelpan ² , Facundo Van Isseldyk ³ , Diego Prado ⁴ , Marcus Vinícius Serra ⁵ , Jin-Sung Kim ⁶

¹ Universidad de La Frontera, Temuco, Chile,

² Hospital Dr. Hernan Henriquez Aravena, Temuco, Chile,

³ Hospital Privado de Rosario, Rosario, Argentina,

⁴ Instituto Neurocirugía Dr. Alfonso Asenjo, Santiago, Chile,

⁵ Santista Institute of Neurosurgery and Spine, Santos, Brazil,

⁶ Seoul St. Mary's Hospital, Neurosurgery, Seoul, South Korea

Introduction: The development of full-endoscopic spine surgery has made it possible to address foraminal pathology in a versatile and effective way, achieving direct and selective decompression, which could avoid the need for routine fusion. In cases of L5-S1 foraminal stenosis, the most used option is the contralateral interlaminar approach; however, in cases of previous interlaminar surgery, this approach can be complicated by fibrosis. Posterolateral transforaminal approaches with in-out techniques are alternatives with a risk of postoperative dysesthesia of up to 30%, caused by injury of the dorsal root ganglion (DRG) or hematoma induced by segmental arterial bleeding. Objective: Present a new docking site using extraforaminal access, as an alternative technique for foraminal pathologies at the lumbar level L5-S1 starting in the pars of L5. This approach may be an option to reduce DRG. We show our early results of the first cases. Material and Methods: Retrospective study. Nine patients with symptomatic L5-S1 degenerative foraminal pathology. Full-endoscopic surgery with extraforaminal access and approach to the L5 pars interarticularis. Operated between 2020 and 2024. Patients with grade 2 or 3 foraminal stenosis, balanced degenerative scoliosis and grade I spondylolisthesis were included. Patients with unstable L5-S1 segments were excluded. The visual analogue scale (VAS), the Oswestry index (ODI), and the modified MacNab criteria were used to evaluate pain clinical results, functional and patient satisfaction. Intraoperative and postoperative complications were recorded. Radiographic follow-up was at 1, 3 months, and one year. The minimum follow-up was three months. Results: A total of nine patients. Seven women, two men, average age 69.1 (50 - 86). The average surgical time was 102 minutes. All patients were discharged within the first 8 hours. An improvement of 42 points was observed in the ODI (preoperative 62.3 - postoperative 19.6), and 5 points in the VAS (preoperative 8.3 - postoperative 2.8). Eight of nine cases had good or excellent results. No cases of postoperative dysesthesia. No de novo instability was evident on dynamic radiographs. No surgical re-interventions. Conclusion: The use of L5 pars as a docking site may be safe, reproducible, and effective in treating L5-S1 foraminal pathology, with minimal blood loss, a low rate of complications, and the preservation of spinal stability. The disadvantages are the longer operative time and the need for experienced, trained surgeons to perform complex lumbar endoscopic surgery. This alternative should be considered as a viable option in patients with a low iliac crest or patients with previous interlaminar surgeries despite having a high iliac crest.

RF02: MIS 1

ID: 1238

RF019: Minimally invasive robotic spondylosis repair

Stanley Kisinde ¹ , Isador Lieberman ¹ , Joseph Albano ¹ , Alexander Satin ¹

¹ Texas Back Institute, Scoliosis & Spine Tumor Center, Frisco, United States

Introduction: Surgical treatment for pars defects, which involves either repair of the defect or fusion, should be considered for patients who have failed extensive conservative measures for spondylolysis. The Buck technique, of which ours is a modification – a minimally-invasive, robotic-assisted approach, has shown healing rates from between 88-100% and resolution of the disc stresses at the affected level as well as the adjacent segments. A less invasive robotic-assisted approach preserves the midline structures as these remain untouched, while also avoiding fusion, which reduces the of risk of adjacent segment degeneration, a particularly important consideration in young patients. This study aimed to investigate the feasibility and clinical outcomes of a minimally-invasive, robotic-assisted pars repair technique. Material and Methods: We retrospectively reviewed patients that underwent minimally-invasive, robotic-assisted pars lysis repair from 2017-2021. We queried the database for patient demographics, type of surgery in terms of levels of lysis/repair, surgical parameters, perioperative complications, pre- and post op PROMs, length of hospital stay, discharge disposition, and return to work/ADLs. Results: 12 screws were successfully placed percutaneously across each of the pars lysis lesions in 7 patients using computer-navigated robotic guidance. There were no intra- or immediate post-operative complications. 2 patients developed pseudarthrosis & loosening of instrumentation and underwent revision involving removal of instrumentation in both cases at least 1 year after the initial procedure, and a subsequent 360 L5-S1 fusion in only one of them. The mean follow-up is about 2yrs with all the patients reporting improvement in their PROMs - 66.6% average reduction in VAS and a 28-point improvement in ODI overall. Conclusion: A percutaneous robotic-assisted technique instead of a traditional open approach and debridement, is feasible with clinically acceptable outcomes.

ID: 2682

RF020: Vascular treatment of segmental arteries in mini-open retropleural approach of thoraco-lumbar LIF corpectomy

Takashi Moriwaki ¹ , Sho Fujiwara ¹ , Koichi Iwatsuki ¹

¹ Osaka Gyoumeikan Hospital, Department of Neuro Spinal Surgery, Osaka, Japan

Introduction: Microneurospinal Surgical Anatomy Conscious of Membranes and Layers is important in Mini-Open Retropleural Approach of Thoraco-Lumbar LIF Corpectomy. The Adamkiewicz artery is present in 83% on the left side of the spine and 83% from T9 to L1(Andrew A Fanous et al., Spine 2015). Vascular treatment of segmental arteries in Mini-Open Thoraco-Lumbar LIF Corpectomy were investigated. Material and Methods: 37 cases of Mini-Open Retropleural Approach of Thoraco-Lumbar LIF Corpectomy (level; T9∼L2, age 76.2y, M/F; 14/23) after November 2019 were examined. Intraoperative microscope video was used to confirm the presence of segmental arteries and blood flow during LIF Corpectomy procedure. Results: Spinal cord infarction was not observed in any of the cases. In 32/37 cases from intraoperative records were available, segmental arteries could be confirmed, in 28/32 cases their blood flows from the intercostal artery (retrograde blood flow) were confirmed when segmental arteries were resected. Mini-Open Retropleural approach, which is based on dissecting the layer between the endothoracic fascia and the parietal pleura different from the layer between Innermost intercostal muscle and Internal intercostal muscle where the intercostal arteries are located, can preserve the intercostal artery blood flow, and is thought to be involved in maintaining retrograde blood flow in segmental artery. Thus Mini-Open Retropleural approach maintains the retrograde blood flow at segmental artery from intercostal artery. And the retrograde blood flow at segmental artery maintains spinal cord blood flow through Anterior radicular artery to Artery of Adamkiewicz. Conclusion: The treatment of segmental arteries in Mini-Open Retropleural Approach of Thoraco-Lumbar LIF Corpectomy is safe.

ID: 515

RF021: Full-endoscopic vs conventional microsurgical therapy of lumbar disc herniation: a prospective, controlled, single-center, comprehensive cohort trial (FEMT-LDH Trial)

Frank Hassel ¹ , Babak Saravi ^1,2 , Alisia Zink ¹ , Uelkuemen Sara ^1,2 , Sébastien Couillard-Després ³ , Gernot Michael Lang ²

¹ Loretto Hospital, Spine Surgery, Freiburg, Germany,

² Faculty of Medicine, University of Freiburg, Orthopedics and Trauma Surgery, Freiburg, Germany,

³ Paracelsus University Salzburg, Institute of Neuroregeneration, Salzburg, Austria

Introduction: Lumbar disc herniation, a predominant cause of chronic low back pain, often necessitates surgical intervention when conservative treatments fail. The advent of full-endoscopic disc decompression (FED) presents a minimally invasive alternative to the traditional microsurgical disc decompression (MSD), yet comparative evidence remains limited. Material and Methods: In this single-center comprehensive cohort trial, patients with lumbar disc herniation were enrolled to receive either FED or MSD. The study design incorporated both randomized and non-randomized arms, catering to patient preference regarding randomization. Primary and secondary outcomes included the Oswestry Disability Index (ODI), Numeric Rating Scale (NRS) for pain, SF-36 health survey, and clinical characteristics (operation time, hospital stay, complications). Additionally, inflammatory markers (C-reactive protein, Procalcitonin, interleukin 6) were evaluated. Mixed effects models analyzed the changes in outcomes over time. Results: Fifty-six patients were analyzed (FED: n = 36, MSD: n = 20). Operation times and hospital stays were comparable between groups. Complication rates necessitating resurgery did not differ significantly. ODI improvements were notable in both groups, with FED showing a more pronounced and consistent enhancement, especially in randomized patients. NRS for back and leg pain significantly decreased in both groups, underscoring the efficacy of both techniques in pain management. The SF-36 General Health scores improved significantly, indicating enhanced patient-perceived health post-surgery. Inflammatory markers highlighted a biological response to surgical trauma without significant systemic inflammation or infection risk, showcasing both techniques' safety. Notably, the MSD group exhibited a slightly better outcome in SF-36 General Health at the 1-year mark and a more pronounced inflammatory response, suggesting differences in the healing trajectory between techniques. Conclusion: Both FED and MSD effectively improved functional and pain outcomes in lumbar disc herniation patients, with minimal complications and similar recovery profiles. FED, particularly in the randomized cohort, showed a more significant improvement in ODI scores, affirming its potential as a viable alternative to MSD. The similar postoperative trajectories in inflammatory markers between groups affirm the safety and minimally invasive nature of FED. These findings advocate for patient-centered decision-making in surgical approach selection, emphasizing the need for further randomized controlled trials to explore the nuanced benefits and applications of full-endoscopic techniques in spinal surgery.

ID: 289

RF022: Minimally invasive versus open approach fracture fixation in ankylosing spine disease

Mostafa Meshneb ¹ , Khalid Salem ¹ , Elie Najjar ¹ , Weronika Nocun ¹ , Ahmed Hassan ^1,2 , Nasir Quraishi ¹

¹ Queen's Medical centre, Nottingham University Hospitals, Nottingham, United Kingdom,

² Department of Orthopedics and Trauma Surgery, Assiut University School of Medicine, Assiut, Assiut, Egypt

Background: Ankylosing spine disease (ASD) patients are at an increased risk of unstable fracture due to the long lever arm in multilevel fused vertebras. While both open (OS) and minimally invasive (MIS) posterior long segment fixation can be used, few studies compared both techniques. Objective: To systematically evaluate the relevant literature regarding the outcomes of MIS versus OS to ankylosed spine fractures with respect to operation time, blood loss, length of hospital stay and complications. Methods: A systematic review of the English language literature using Pubmed, Embase and Cochrane and dating up until September 2023 was undertaken following Preferred Reporting Items for Systematic Review and Meta-Analysis guidelines. Results: Of the initial 381 articles, 5 were relevant (level III evidence) and were analyzed. A total of 77 ASD patients with spine fractures underwent OS fixation. Their average age was 68.9 (55-81) years, the male to female ratio was 63/14. 78% of the fractures were thoracic, 18% were lumbar and 4% were cervical. 87% of patients had AO type B fractures and 13% had type C. The average operative time was 247 (153-253) min with average blood loss of 863 (409-1248) cc. The average hospital stay was 32.2 (15-42) days. During an average follow-up of 42 months, the rate of complications was 16%. Additionally, 123 ASD patients with spinal fractures underwent MIS fixation. Their average age was 72 (58-77) years and the male to female ration was 91/32. 88% of the fractures were thoracic and 12% were lumbar. 94% of the patients had AO type B fractures and 6% had type C. The average operative time was 187 (127-170) min with average blood loss of 347 (185-700) cc. The average hospital stay was 14.9 (14-21) days. During an average follow-up of 47 months, the rate of complications was 6%. Statistical analysis comparing MIS to OS techniques showed significant reduction in operative time (p = 0.006), blood loss (p < 0.001), hospital stay (p = 0.002), and complication rates (p = 0.01). There was no statistical significance comparing both groups, average age, location of fractures or AO types. Conclusion: This is the first systematic review comparing MIS vs OS in ASD. MIS fixation had significantly shorter operative time and lower blood loss, hospital stay, and complication rates compared to OS technique.

ID: 2232

RF023: Effectiveness and safety of intrathecal morphine for percutaneous endoscopic lumbar discectomy: a prospective, randomized, double-blind clinical trial (the IMPELD trial)

Lei Yue ¹ , Jianming Zhang ¹ , Haolin Sun ¹

¹ Peking University First Hospital, Beijing, China

Introduction: Percutaneous endoscopic lumbar discectomy (PELD) is a surgical setting that requires minimal motor impairment. Low-dose spinal ropivacaine induces little motor blockade and could be ideal for maintaining safety of PELD, but its analgesic efficacy is questionable. An adjunct analgesic approach is needed to maximize the benefits of low-dose spinal ropivacaine for PELD. Material and Methods: A double-blind, randomized, placebo-controlled trial. Trial registration: ChiCTR2000039842 (https://www.chictr.org.cn). Sample: Ninety patients scheduled for elective single-level PELD under low-dose spinal ropivacaine.Outcome measures: The primary outcome was the overall intraoperative visual analogue scale (VAS) score for pain. Secondary outcomes were intraoperative VAS scores assessed at multiple timepoints; intraoperative rescue analgesic requirement; postoperative VAS scores; disability scale; patients' satisfaction with anesthesia; adverse events; and radiographic outcomes. Methods: Patients were randomized to receive low-dose ropivacaine spinal anesthesia with (ITM group, n = 45) or without (control group, n = 45) 100 µg ITM. Results: The overall intraoperative VAS score in the ITM group was significantly lower than that in the control group (0 [0, 1] vs 2 [1, 3], p < .001). During operation, the VAS scores at cannula insertion, 30 minutes after insertion, 60 minutes after insertion, and 120 minutes after insertion were all significantly lower in the ITM group (all p < .05). Less patients in the ITM group required rescue analgesia during operation compared with those in the control group (14% vs 42%, p = .003). The VAS score for back pain in the ITM group was lower than that in the control group at 1 hour, 12 hours, and 24 hours postoperatively. Besides, the satisfaction score in the ITM group was significantly higher than that in the control group (p = .017). For adverse events, 8/43 of ITM and 1/44 of control participants experienced pruritus (p = .014), with a relative risk (95% confidence interval) of 8.37 (1.09-64.16). The incidence of other adverse events was similar between the two groups. Of note, respiratory depression occurred in one ITM-treated patient. Conclusion: The addition of 100 µg ITM to low-dose ropivacaine appears to be effective in analgesia without compromised motor function for PELD; however, ITM increased the risk of pruritus and clinicians should be vigilant about its potential risk of respiratory depression.

ID: 1984

RF024: Outcome of minimal invasive scoliosis surgery in adolescent idiopathic scoliosis

Muhammad Jawad Saleem ¹

¹ Orthopedic Spine Institute, Lahore, Pakistan

Objective: Here we are presenting outcome of minimally invasive scoliosis surgery (MISS). Methods: This prospective case series was carried out using probability consecutive sampling technique. The study was conducted at Orthopedic Spine Institute, Doctors Hospital & Medical Centre, Lahore from 1^st March 2017 to 28^th February 2022. A sample size of 51 patients presented in our hospital with flexible curves between 40 to 70 degree recruited in the study and followed prospectively. Patients with rigid curves, curves more than 70 degree and congenital scoliosis were excluded from study. All patients had pre-operative radiograph and Screening MRI. All patients were operated by the same surgeon. The outcome measures were degree of correction achieved and hospital stay. Patients were followed up at 3 weeks, 6 weeks, 12 weeks, 6 months and then yearly. Results: The mean age was 16.5 year. Average duration of surgery was 5.6 hours in first 15 cases then 3.5 hours for last 36 cases. Mean estimated blood loss was 250cc. Two transient neuro-monitoring changes intra-operative that returned to baseline during surgery. One infection of the superior portal. All patients were mobilized on first postoperative day. Mean hospital stay was 2.8 days. Average Cobb Angle was 55.6 pre-operatively and 13.8 post-operatively. Time to return school was 18-27 days. Conclusion: In the short term this procedure decreases the morbidity of the open surgery. In the long run hopefully will decrease the incidence of junctional problems associated with long segment fusions

Keywords: Minimally Invasive Scoliosis Surgery (MISS)

ID: 2357

RF025: Full-endoscopic lumbar spine discectomy: are we finally there? A meta-analysis of its effectiveness against conventional and tubular microdiscectomy

Kajetan Latka ¹ , Dariusz Latka ¹ , Kacper Domisiewicz ¹ , Piotr Lasowy ¹ , Klaudia Kozłowska ²

¹ Institute of Medicine, Neurosurgery, Opole, Poland,

² Wroclaw University of Science and Technology, Wrocław, Poland

Introduction: Full-endoscopic lumbar discectomy (FELD) has gained increasing attention as a minimally invasive alternative to conventional microdiscectomy (MD) and open discectomy (OD). Over the past decade, significant technological advancements have been made in endoscopic techniques, yet it remains unclear whether FELD offers a definitive advantage over more traditional methods. This meta-analysis focuses on studies published between 2013 and 2024 to reflect the most up-to-date clinical evidence regarding FELD’s effectiveness in comparison to MD, tubular microdiscectomy (MED), and OD, with particular attention to operative time, clinical outcomes, complications, and reoperation rates. Material and Methods: A systematic review and meta-analysis were conducted following PRISMA guidelines. We searched PubMed, Embase, Web of Science, and the Cochrane Library for studies published between 2013 and 2024 that compared FELD to MD, MED, or OD. The primary outcomes included visual analog scale (VAS) for back and leg pain, Oswestry Disability Index (ODI), complications, and reoperation rates. Subgroup analyses were performed for randomized controlled trials (RCTs) and non-randomized trials (nonRCTs), and heterogeneity was assessed using the I² statistic. Results: A total of 84 studies, including 14 randomized controlled trials (RCTs), with 16,785 patients were included in this meta-analysis. Our analysis revealed that FELD resulted in significantly better short-term outcomes in terms of VAS back pain and ODI scores compared to MED and OD. In the subgroup analysis, TELD demonstrated superior functional improvement at 6 months, while no significant differences were found at 12 and ≥ 24 months. Operative time showed no significant differences between FELD and MD, although FELD showed a trend towards a slightly shorter operative time in randomized controlled trials. No significant differences were observed in reoperation rates or complications across any of the groups. Heterogeneity was high for several outcomes, reflecting the variability in study design and reporting standards. Conclusion: FELD demonstrates several advantages, particularly in terms of short-term pain relief and faster patient mobilization, while maintaining similar risks of recurrence, reoperation, and complications compared to traditional techniques. However, the heterogeneity of existing studies and the lack of high-quality prospective randomized trials suggest that further research is necessary to establish FELD as the new gold standard. Well-designed studies, with a focus on long-term outcomes, radiological findings, and cost-effectiveness, are essential to fully evaluate the potential of endoscopic spine surgery.

ID: 2571

RF026: Direct posterior intradural surgical repair in the management of the spontaneous spinal cerebrospinal leak: a six-year retrospective Canadian cohort study

François Dantas ¹ , Karlo Pedro ¹ , Jed Lazarus ¹ , Peyton Lawrence ¹ , Eric Massicotte ¹

¹ University of Toronto, University Health Network - Toronto Western Hospital , Neurosurgery, Toronto, Canada

Introduction: Spinal cerebrospinal fluid (CSF) leaks can lead to intracranial hypotension, with a wide range of clinical presentations. This condition is rare, making both diagnosis and treatment challenging. Surgical repair remains the primary treatment for persistent CSF leaks, particularly those unresponsive to epidural blood patches. Surgical technique includes direct repair of the dura, however, getting to the dural defect can present challenges. This contributes to variations in approach and repair techniques described in the literature. Our previous work introduced a systematic classification for spontaneous spinal CSF leaks using MRI and digital subtraction myelography, identifying 4 distinct types. This study aims to describe the clinical profile, postoperative outcomes, and predictors of symptom resolution following posterior primary dural repair. Methods: This single-center retrospective cohort study included all consecutive patients diagnosed with spontaneous spinal CSF leak, surgically treated between June 2017 and December 2023. Symptoms at initial presentation and duration were examined. All patients underwent preoperative full spine and brain magnetic resonance imaging (MRI). Digital subtraction myelogram was performed to identify the location and type of CSF leak. Leaks were classified as: ventral dural tear (type 1), lateral dural tear (type 2), CSF-venous fistula (type 3), and distal nerve root sleeve leak (type 4). Associated pathologies, such as calcified discs or osteophytes, and spinal longitudinal extradural collection (SLEC) were analyzed. All patients underwent microscopic, open, posterior, intradural primary surgical repair of leak with intraoperative neuromonitoring. The primary outcome was symptom improvement, as reported by patients at the first follow-up. Postoperative complications were recorded, and follow-up evaluations were performed multiple times after surgery with postoperative full spine and brain MRI. We assessed the association between variables and outcome using univariate and multivariate regression analysis. Results: A total of 40 patients, with an average age of 50.48 years (±11.88) were included. The majority (72.5%) had Type 1 leaks, followed by Type 3 (20%), and Type 2 (7.5%). Laminectomy (18/40) or laminoplasty (13/40) were the most common surgical approach for Type 1 and 2 leaks, respectively, while a minimally invasive approach was used for Type 3 lesion. The mean duration from symptom onset to surgery was 41 (±54.3) months, with no significant difference between leak types (p = 0.28). The thoracic region was the most common leak location (39 patients). SLEC was most frequently observed in Type 1 leak (86.2%), while cranial stigmata were most common in Type 2 leaks (33.3%). Microscopic direct dural repair led to symptom resolution in 34 patients (85%), with headache improvement in 33 patients (82.5%). Two patients experienced transient motor weakness as the only reported complication. Preoperative SLEC and cranial stigmata resolved in 27.5% and 60% of patients, respectively, by at least six months postoperatively. Regression analysis identified preoperative cranial stigmata as a significant predictor of symptom resolution following surgical intervention. Conclusion: Direct posterior surgical repair is a safe and effective treatment for spontaneous spinal CSF leaks, leading to significant symptom improvement at six months after surgery. Accurate preoperative identification of leak location and cranial stigmata is crucial for optimal surgical planning and outcome prediction.

ID: 1499

RF027: Is there a difference in unilateral versus bilateral facetectomy in an open or MIS TLIF? A systematic review and meta-analysis

Mohamed Macki ¹ , Mario-Cyriac Tcheukado ¹ , George Nageeb ¹ , Michael Steinmetz ¹

¹ Cleveland Clinic Foundation, Neurological Insitute, Cleveland, United States

Objective: To compare radiological, operative, and clinical outcomes of a unilateral versus bilateral facetectomy for the transforaminal lumbar interbody fusion (TLIF) utilizing an open approach or minimally invasive surgery (MIS). Material and Methods: Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, a comprehensive search of research databases yielded 9 clinical cohort studies that explicitly compared unilateral versus bilateral facetectomy for TLIF for degenerative lumbar pathology: 2 open-only, 6 MIS-only, and 1 combined MIS-open TLIF publications. Forest plots generated a pooled analysis for each outcome measure. Results: Meta-analyses found no difference in lumbar lordosis between facetectomy procedures in open-only, MIS-only, or combined groups. Disc height change was similar in MIS-only and combined groups but not reported in open-only articles. In MIS-only publications, bilateral facetectomy was associated with higher operative blood loss, postoperative drainage, and surgical duration. One open-only publication reported that bilateral facetectomy experienced statistically significantly greater ΔPHQ-9 (-4.6 ± 5.2 vs -0.8 ± 4.6, p = 0.03) and ΔQALY (0.3 ± 0.2 vs 0.1 ± 0.2, p = 0.01). One MIS-only publication reported that unilateral facetectomy incurred significantly greater ΔODI-2yrs (25.8 ± 23.5 vs 8.2 ± 29.6, p = 0.026) while bilateral facetectomy had a greater ΔPROMIS-PF-2yrs (13.7 ± 4.4 vs 3.7 ± 4.0). Conclusion: Regardless of surgical technique, unilateral facetectomy is comparable to bilateral facetectomy with respect to radiologic, operative, and clinical outcomes. The unilateral approach in MIS TLIF has the added benefit of decreased blood loss, operative time, and drainage, while these parameters were not specifically compared in the open-only TLIF studies. The role of a unilateral facetectomy for standard lumbar degeneration is an acceptable and favorable approach, which is particularly valuable in MIS TLIFs wherein only a single facet is exposed.

ID: 1511

RF028: Dural tears in uniportal vs biportal endoscopic spine surgery: a comparative systematic review

Yusuf Ansari ¹ , Arwa Alabide ² , Saqib Hasan ³

¹ Temple University, Philadelphia, United States,

² Hurley Medical Center, Flint, United States,

³ Golden State Orthopedics and Spine, Oakland, United States

Introduction: Endoscopic spinal surgery has gained popularity for its minimally invasive nature, offering patients reduced recovery times, smaller incisions, and fewer complications compared to traditional open surgery. However, one of the key complications that remains a concern is the occurrence of dural tears. This systematic review aims to assess the effectiveness, complications, and specifically the relationship between unilateral and bilateral endoscopic procedures and the occurrence of dural tears. Methods: Following PRISMA guidelines, a systematic search of electronic databases including PubMed, Google Scholar, and Scopus was conducted using relevant keywords: “endoscopic spine surgery”, “dural tears”, and “incidental durotomy” were used to identify relevant studies published up to September 2024. Studies report patients who underwent spinal surgery and reported postoperative complications especially dura tears were included. Data extraction and quality assessment were performed independently by two reviewers. included descriptive statistics and chi-square tests to explore the relationship between the type of procedure and the incidence of dural tears using the R program. Results: The review analyzed data from 4774 patients, with females predominant (616). The weighted mean (SD) age of patients was 59.99 ± 13.81 years, and the BMI was 24.93 (5.126). Disc herniation was the most frequent indication for surgery (4063, 85.19%), with L5-S1 most commonly affected. Biportal endoscopic spinal surgery was the most common surgical indication (1551, 33.5%). The mean (SD) operation time was 97.40 (59.38) minutes, and the mean (SD) estimated blood loss was 171.86 (192.22) ml. Dural tears occurred in 103 (4.63%) patients, with 81 treated by bed rest. The mean (SD) hospital stay was 5.24 (5.68) days. Postoperative improvements in Visual Analog Scale (VAS) pain scores and Oswestry Disability Index (ODI) were observed across all techniques. A chi-square test comparing unilateral and bilateral procedures yielded a chi-square statistic of 0.064 and a p-value of 0.800, indicating no significant difference in dural tear rates or postoperative outcomes between the two approaches after a mean follow-up of 23.71 (11.6) months. Conclusion: The various endoscopic spinal surgery techniques result in similar postoperative outcomes regarding the occurrence of dura tears as a complication. There is no statistically significant relationship between the type of procedure and the occurrence of dural tears, indicating that factors other than the type of endoscopic approach may influence tear duration.

ID: 1889

RF029: Robot-assisted minimally invasive cortical bone trajectory (CBT) screw fixation in lateral transpsoas interbody fusion: a clinical experience

Nicola Marengo ¹ , Federico Pecoraro ² , Enrico Lo Bue ¹ , Stefano Colonna ¹ , Marco Ajello ¹ , Francesco Zenga ¹ , Fabio Cofano ¹ , Diego Garbossa ¹

¹ A.O.U. Città della Salute e della Scienza, Neurosurgery, Turin, Italy,

² Casa di Cura Sileno e Anna Rizzola - San Donà di Piave (VE), Neurosurgery, San Donà di Piave, Italy

Introduction: Lateral lumbar interbody fusion (LLIF) is a commonly used minimally invasive procedure for lumbar interbody fusion. The cortical bone trajectory (CBT) is a novel lumbar posterior fixation technique with screws following a mediolateral route in the axial plane and a caudo-cephalad route in the sagittal plane. Biomechanical strength has been demonstrated in many different cadaveric studies. Placement accuracy is fundamental considering the potential complications of screw malpositioning. In recent years, a multitude of technologies have been reported to improve accuracy of screw placement such as navigation software, neuromonitoring, custom-made template guides and robot-assisted surgery. We present our clinical experience of robot-assisted CBT screw placement for posterior fixation in LLIF. Material and Methods: This multicenter retrospective observational study of prospectively collected data included 62 patients surgically treated with LLIF and robot-assisted minimally invasive CBT screw fixation. The surgical procedure was either performed with a double-position or single-lateral position. The choice of a single-position technique was adopted when indirect decompression was considered feasible and effective based on preoperative foraminal height and spinal stenosis according to Schizas classification. All the screws were implanted using a robot-assisted navigation system through a single median incision with subfascial-transmuscular technique. Short and long-term postoperative complication were evaluated in all patients. Postoperative radiological evaluation included a CT scan to evaluate screw placement accuracy according to Gertzbein classification and an MRI performed at least 1 year from the surgery to evaluate the indirect decompression and the grade of muscle atrophy in terms of T2-ratio and multifidus cross-sectional area (MF-CSA). Results: A total of 62 patients were surgically treated with LLIF and robot-assisted minimally invasive CBT screw fixation. Overall, a total of 70 levels were treated, with 55 (88.7%) patients treated with a single-level procedure, and 7 (11.3%) patients treated with a multi-level procedure. In aggregate, 264 screws were implanted, with 208 (78.8%) screws positioned in double-position technique, and 56 (21.2%) screws positioned in single-position technique. Overall accuracy of screw positioning was 94%, with 16 (6%) grade 1 malpositioned screws according to Gertzbein classification. No statistically significant differences of accuracy were found between different levels, nor between single- or double-position procedures. Long-term complication included 2 (3.2%) cases of pseudoarthrosis not requiring surgical revision; short-term complication included 3 (4.8%) cases of postoperative epifascial seroma. All cases treated with single-lateral technique achieved effective indirect decompression at postoperative lumbo-sacral MRI evaluation. Overall, the grade of postoperative muscular atrophy was lower compared to results from open fusion techniques available in the literature. Conclusion: Robot-assisted CBT screw placement for posterior fixation in LLIF is an accurate and effective technique for spinal fusion surgery. This technique was found to be an excellent solution to obtain precise screw insertion and decrease the incidence of postoperative complication. The proposed surgical technique aims to combine the biomechanical advantages of CBT screws, the reduction of postoperative muscular damage, and the use of innovative robot-assisted technology for screw placement.

ID: 1422

RF030: Anatomical positional variations of retroperitoneal organs and lumbar lordosis angle changes during single-position prone lateral lumbar interbody fusion

Qiang Yang ¹ , Chao Chen ¹

¹ Tianjin Hospital of Tianjin University, Tianjin, China

Introduction: For the first time, we used patients scheduled for LLIF surgery as research subjects and performed CT measurements in three different decubitus: prone, right lateral, and oblique (30°), ensuring that the abdomen was freely hanging to best replicate the patient's intraoperative state. We analyzed the positional changes of retroperitoneal organs such as the psoas major, blood vessels, and left kidneys, as well as the lumbar lordosis angle in the three different decubitus. Accurately mastering the positional changes of retroperitoneal organs in different positions is crucial for the selection of surgical approach and surgical safety. Material and Methods: Patients included in this study underwent CT scans in three decubitus: prone, right lateral, and oblique. Measurements were taken of the anatomical positions of the psoas major, abdominal aorta, left common iliac arteries, and left kidneys at the L1/2-L4/5 disc levels, as well as changes in the lumbar lordosis angle in different decubitus. Results: The study included 18 patients scheduled for lateral lumbar interbody fusion surgery, with an average age of 54 years (range 30-74 years), including 6 males and 12 females. Significant changes were observed in the thickness of the psoas major, the outer edge of artery, lumbar lordosis angle, and kidney position across the three positions. Compared to the lateral decubitus, in the prone decubitus, the thickness of the psoas major increased by 4.07 ± 3.41 mm (p < 0.05), the abdominal aorta shifted laterally by 2.29 ± 2.79 mm (p < 0.05), the left common iliac artery shifted laterally by 1.98 ± 3.54 mm (p < 0.05), the anterior movement of the kidney was 6.97 ± 5.84 mm (p < 0.05), and the lumbar lordosis angle increased by 7.73 ± 3.76° (p < 0.05). Compared to the lateral decubitus, in the oblique decubitus, the thickness of the psoas major muscle increased by 3.14 ± 3.36 mm (p < 0.05), the abdominal aorta shifted laterally by 1.59 ± 2.82 mm (p < 0.05), the left common iliac artery shifted laterally by 2.45 ± 4.51 mm (p < 0.05), the anterior movement of the kidney was 3.92 ± 4.70 mm (p < 0.05), and the lumbar lordosis angle increased by 3.04 ± 3.55° (p < 0.05). When comparing the prone decubitus with the oblique decubitus, the anterior movement of the kidney was 3.06 ± 3.74 mm (p < 0.05), and the increase in the lumbar lordosis angle was 4.68 ± 3.53° (p < 0.05). Conclusion: Compared to traditional lateral lumbar interbody fusion, single-position prone lateral lumbar interbody fusion shows significant changes in retroperitoneal organs and lumbar lordosis angle, with increased thickness of the psoas major; displacement of the abdominal aorta and left common iliac arteries; anterior displacement of the kidneys; and an increased lumbar lordosis angle. These findings are of great significance for preoperative planning and surgical safety in single-position prone lateral lumbar interbody fusion.

ID: 739

RF031: Comparison of minimally invasive lumbar decompression in the management of lumbar stenosis with and without degenerative spondylolisthesis

Lauren Barber ^1,2 , Stone Sima ² , Charmian Stewart ² , Alisha Sial ^2,3,4 , Ashish Diwan ^2,3,4

¹ Virginia Commonwealth University, Orthopaedics, Richmond, United States,

² Spine Labs, St George and Sutherland Clinical School, UNSW, Sydney, Australia,

³ Spine Service, Orthopaedics, St George Hospital, Sydney, Australia,

⁴ Spinal Surgery, Discipline of Orthopaedic Surgery, The University of Adelaide, Adelaide, Australia

Introduction: As the global life expectancy continues to rise, the incidence of degenerative spinal disease has also increased. Lumbar decompression is a proven treatment for the management of degenerative spinal disease. Though back and leg pain are key symptoms of both lumbar stenosis with (+DS) and lumbar stenosis without (-DS) degenerative spondylolisthesis, they are two different pathologies with different mechanisms of disease. Nevertheless, both pathologies can be managed with lumbar decompression. However, there is a paucity of literature evaluating patient reported outcomes (PROs) after lumbar decompression between +DS and -DS. This study aims to compare patient reported outcomes between patients undergoing decompression for +DS and -DS using a novel spinous process osteotomy decompression technique, which maintains midline attachments. Methods: This is a prospective cohort study of adult patients (> 18 years old) who underwent 1-3 level lumbar decompression between 2020 and 2023 using a novel spinous process osteotomy technique. This technique involves a unilateral soft tissue exposure, an osteotomy at the junction of the spinous process and the lamina, and sub-spinous process contralateral exposure. Through this approach, bilateral decompression with maintenance of all midline attachments can be achieved. All patients had a diagnosis of lumbar stenosis with or without degenerative spondylolisthesis. In addition to demographic variables, comparison between pre-operative and post-operative back and leg visual analogue scale (VAS), and Oswestry disability index (ODI) at baseline, 3-, 6-, and 12-months were evaluated. Results: 112 total patients were included with an average age of 64 ± 17 years. 56% of the patients were male and 57% had a diagnosis of -DS. Males had a higher rate of -DS compared to +DS ( ${\chi }^2$ = 5.3, p < 0.05), patients with +DS were older (69 ± 15 vs. 61 ± 17, p < 0.05). When compared to baseline VAS and ODI there was significant improvement at all time points for both groups. There was no significant difference in leg VAS and ODI at all timepoints when comparing patients undergoing decompression for +DS vs -DS. However, patients with +DS had a higher back VAS at 6 (4.7 ± 3.2 vs. 3.4 ± 3.0, p < 0.05) and 12 (5.2 ± 3.2 vs. 3.2 ± 2.9, p < 0.05) month when compared to patients with -DS. Discussion: Though +DS and -DS are different degenerative pathologies, both groups had similar outcomes in pain, disability, and quality of life following decompression using this novel spinous process osteotomy decompression technique. Thus, these findings suggest lumbar decompression alone can be a useful strategy in lumbar stenosis both with and without degenerative spondylolisthesis. This is particularly important given the concerns for inducing or worsening instability with decompression of degenerative spondylolisthesis. These results can not only serve as a pre-operative clinical decision-making guide, but also as a post-operative expectation management tool in patients with degenerative spinal diseases.

ID: 1520

FR032: Minimally-invasive, cervical pedicle screw fixation using image-guided technology as an alternative method for the treatment of subaxial cervical fractures

Lukas Bobinski ¹ , Johan Wänman ¹

¹ Spine Unit, Department of Orthopedics, Umeå University Hospital, Department of Diagnostics and Intervention, Umeå University, Umeå, Sweden

Introduction: Posterior cervical fixation requires wide access and significant muscle dissection. This can be associated with excessive blood loss and an increased risk for postoperative complications, such as infection, muscle atrophy, or adjacent level disease. We present a preliminary report on 30 consecutive patients treated with minimally-invasive, cervical pedicle screw (MICEPS) fixation as an alternative treatment for unstable fractures in the subaxial spine. Material and Methods: The data were collected retrospectively from medical and radiological records of patients operated at the spine unit, department of orthopedics, Umeå University Hospital (NUS), Umeå. Image-viewing software (SECTRA) was utilized for the classification of screw position along the axis of the bone corridor of pedicle using the orthogonal view evaluation method (OVEM) defined as follows: 1 (no breach), 2 (screw thread breach only), 3 (any breach larger than grade 2 without neurovascular injury) and 4 (grade 3 breach causing neurovascular injury). All patients underwent fully navigated surgery (O-arm^TM in combination with Stealth Station, Medtronic) with cervical pedicle screws (CPS) using a tubular access system (MetrX Quadrant). Surgery in cervico-thoracic junction was performed using a combination of tubular access and fully percutaneous system for thoracic screws (Voyager/Longitude, Medtronic). Descriptive and inferential statistics were performed. Results: A total of 30 patients (26 men, 4 women) with cervical fractures, were enrolled. The mean age was 64 years (57-71, 95% CI). Twenty-one (70%) of the patients were classified as ASA 3 or 4. Fourteen (47%) sustained fractures due to ankylosing spondylitis (AS) or diffuse idiopathic skeletal hyperostosis (DISH). A total of 147 (133 cervical and 14 thoracic) screws were implanted. Of these, 115 (78%) screws were classified as OVEM 1 or 2, and 32 (22%) as OVEM 3. There were no OVEM 4 screws. Eleven (37%) of the patients underwent MICEPS in combination with anterior surgery. The mean surgical time was 179 (150-208, 95% CI) minutes with a mean blood loss of 137.9 ml (CI: 97.8-175). The mean radiological follow-up was 9.5 months (CI: 6.4-11.8), with three patients lost to follow-up. There were no intraoperative complications and no postoperative neurological deteriorations. There were no postoperative infections. Fusion was achieved in 100% of radiologically followed patients. One patient deceased in post-operative period due to alkalosis and cachexia associated with alcohol abuse. One patient with advanced cardio-vascular disease developed a clinically silence pulmonary embolism, which was successfully treated. One patient presented with atrophy of the trapezius muscle caused by direct tubular access. Following the adoption of percutaneous fixation with the thoracic system, we did not encounter any more cases of muscle atrophy. One patient underwent planned screw removal following temporary, unilateral fixation due to pedicle and facet fracture. Conclusion: Our results indicate that MICEPS can be succesfuly used for the treatment of subaxial cervical fractures. This method can be especially beneficial for frail patients who require posterior cervical stabilization by minimizing the risks for peri- and postoperative complications.

ID: 909

RF033: Efficacy of expandable and static cages in LLIF surgery: a comparative analysis of preoperative and postoperative disc height and indirect decompression

Akihiko Hiyama ¹ , Nobuaki Hattori ¹ , Satoshi Nomura ¹ , Hiroyuki Katoh ¹ , Daisuke Sakai ¹ , Masahiko Watanabe ¹

¹ Tokai University School of Medicine, Department of Orthopaedic Surgery, Isehara, Kanagawa, Japan

Introduction: Expandable cages, designed to allow in-situ expansion to match lumbar alignment, are often perceived as superior to static cages in restoring disc height (DH). Despite this assumption, there is a lack of comprehensive studies directly comparing the radiological outcomes of indirect decompression using expandable cages in lateral lumbar interbody fusion (LLIF). This study aims to investigate and compare the preoperative and postoperative imaging outcomes between patients treated with an expandable LLIF cage (RISE-L, Globus Medical) and those treated with a static LLIF cage. This study specifically focuses on parameters such as anterior disc height (ADH), posterior disc height (PDH), segmental disc angle (SDA), and measures of spinal canal decompression. Materials and Methods: The study included 104 patients (59 males, 45 females; mean age at surgery: 71.4 years) who underwent LLIF with percutaneous pedicle screw (PPS)-based indirect decompression for conditions such as lumbar spinal stenosis or spondylolisthesis with instability. Surgeries were performed between July 2020 and May 2024. Both preoperative and postoperative CT and MRI images were analyzed to evaluate the surgical outcomes. The patients were divided into two groups: the expandable cage group (E group: 51 patients, 77 disc levels) and the static cage group (S group: 53 patients, 76 disc levels). ADH, PDH, and SDA were measured using CT images. In contrast, the dural sac’s cross-sectional area (CCA) and anteroposterior canal diameter (CD) were measured from MRI axial and sagittal views. Both the expandable and static cages used in this study were titanium. The statistical analysis was performed using the t-test or Mann-Whitney U test, and significance was set at p < 0.05. Results: In the expandable cage group (E group), ADH and PDH increased from 5.9 ± 3.3 mm and 3.4 ± 2.6 mm preoperatively to 10.7 ± 1.8 mm and 7.7 ± 1.8 mm postoperatively. In the static cage group (S group), ADH and PDH increased from 6.4 ± 3.6 mm and 4.1 ± 2.5 mm preoperatively to 10.9 ± 2.2 mm and 7.7 ± 1.8 mm postoperatively. The SDA increased from 3.5 ± 4.2° to 4.8 ± 2.8° in the E group and from 3.5 ± 3.9° to 5.2 ± 3.0° in the S group. However, no statistically significant differences in these parameters were observed between the two groups. Similarly, the CCA and CD improved from 55.8 ± 35.8 mm² and 5.0 ± 2.4 mm preoperatively to 89.7 ± 36.1 mm² and 8.3 ± 2.5 mm postoperatively in the E group, and from 53.9 ± 33.3 mm² and 4.9 ± 2.4 mm to 82.4 ± 32.4 mm² and 7.8 ± 2.1 mm in the S group. Again, the groups had no significant differences regarding dural sac expansion or canal diameter restoration. Conclusion: This study's findings demonstrate no significant differences between expandable and static cages regarding DH restoration, SDA correction, or indirect decompression as measured by spinal canal expansion. Unlike posterior approaches, where facetectomy and other invasive techniques may enhance outcomes, the LLIF procedure - without requiring facet joint resection - showed no significant advantage of the expandable cage over the static cage. Therefore, in the context of LLIF surgery, both types of cages appear to provide similar radiological outcomes, and the use of expandable cages does not offer a notable benefit over static cages in terms of achieving the desired indirect decompression and spinal alignment.

ID: 887

RF034: Assessing the accuracy and safety of the robotic assisted spine surgery in pedicle screw replacement: a retrospective clinical study with 2200 patients

Josh Schroeder ¹ , Leon Kaplan ¹ , Ohad Einav ¹

¹ Hadassah Medical Center, Department of Orthopedics, Jerusalem, Israel

Introduction: Robotic surgery is increasingly utilized in spinal fusion surgery for improved accuracy and safety in pedicle screw placement. This study aimed to evaluate the real-world performance of this robotic system through an extensive clinical experience. Material and Methods: A total of 2200 patients underwent spinal fusion surgery using the robotic surgery (Mazor, Medtorinc) between 2010 and 2024. Patient data was retrospectively analyzed to assess the robot's execution rate, accuracy in pedicle screw placement, and the occurrence of neurological deficits. Results: A total of 10,000 pedicle screws were implanted in 2,200 patients, with each patient receiving between 2 and 26 screws. The surgeries were performed for various indications, including trauma, tumors, degenerative spine conditions, and spinal deformities. There was a 95% execution rate. Among these successful executions, the accuracy rate for pedicle screw placement was 93.2%. Four neurological deficits were observed across the entire patient cohort. Conclusion: The accuracy and safety rates observed in this study compare favorably to those reported in the literature for free-hand and navigation-guided techniques for spine surgery. The robotic system appears to offer a significant advantage in terms of precision and reducing the risk of complications.

ID: 696

RF035: Safety and efficacy evaluation of targeted lateral recess approach for treating radicular canal stenosis under full-view spine endoscopy

Kunfeng Song ¹ , Honggang Zhou ¹

¹ Third People's Hospital of Henan Province, Minimally Invasive Spine Surgery Center, ZhengZhou, China

Introduction: To evaluate the safety and clinical efficacy of the targeted lateral recess approach for treating radicular canal stenosis under full-view spine endoscopy. Material and Methods: A total of 120 patients diagnosed with radicular canal stenosis at our hospital between July 2020 and June 2022 were included in the study. All patients underwent minimally invasive spine endoscopic surgery under local infiltration anesthesia combined with intravenous anesthesia. A targeted lateral recess approach was employed to maximize the preservation of the facet joint's integrity. Surgical duration, intraoperative blood loss, and postoperative complications were recorded. Clinical outcomes were assessed using the Visual Analog Scale (VAS) for pain, the Oswestry Disability Index (ODI), and the modified MacNab criteria at the last follow-up. Results: All patients successfully completed the surgery. The operation time ranged from 40 to 95 minutes, with an average of 62.55 ± 12.35 minutes. Intraoperative blood loss ranged from 10 to 50 milliliters, with an average of 30.19 ± 19.25 milliliters. Postoperative complications included three cases of recurrent nucleus pulposus compression on the dural sac, which improved after percutaneous endoscopic revision; one case of muscle weakness, which recovered after rehabilitation therapy; and one case of numbness, which resolved with conservative treatment. VAS and ODI scores at 1 day, 3 months, and 6 months postoperatively showed significant improvements compared to preoperative scores (p < 0.05). The follow-up period ranged from 12 to 24 months, with an average of 20.52 ± 4.75 months. At the final follow-up, the modified MacNab criteria showed an excellent and good rate of 98.6%. Conclusion: The targeted lateral recess approach under full-view spine endoscopy for the treatment of radicular canal stenosis is safe and demonstrates satisfactory early clinical efficacy.

ID: 847

RF036: Relationship between the oblique corridor at l4-l5 and the morphology of the left psoas in the different types of Roussouly

Juan Pablo Taleb ^1,1 , Juan Pablo Guyot ¹ , Enrique Miguens ¹ , Ruy Lloyd ¹ , Emanuel Zaragoza ¹ , Santiago Suarez Crespo ¹ , Eduardo Galaretto ¹

¹ Hospital Universitario Austral, Pilar, Argentina

Introduction: Roussouly classified different morphological types of spines based on sagittal alignment. The oblique corridor is defined as the distance between the left psoas muscle and the aortoiliac vessels. There are no studies that evaluate what happens with the oblique corridor at the L4-L5 level and the morphology of the left psoas in the different Roussouly types. Material and Methods: We retrospectively analyzed our center's database, identifying all patients who underwent spinograms and lumbar spine MRIs between January 2023 and June 2024. Exclusion criteria: deformities (scoliosis > 20°, lytic spondylolisthesis), L5 sacralization, patients younger than 18, incomplete studies and previous spine surgeries. Of the 342 patients analyzed, 162 met the inclusion criteria. Variables: age, sex, L4-L5 oblique corridor (Ng JP et al., and in millimeters), left psoas morphology (modified Moro classification), spinopelvic parameters (PI, SS, PT, TPA), and Roussouly type. We used the Surgimap and Visual Medica software. This study was approved by the ethics committee. Results: Among the 162 patients analyzed, the median age was 47.50 years (median [IQR] 32.00, 61.00), and 66% were men (n = 107). We identified five Roussouly types: 1 (n = 39, 24.1%); 2 (n = 15, 9.3%); 3 (n = 58, 35.8%); 3A (n = 14, 8.6%); and 4 (n = 36, 22.2%). Patients with Roussouly 3A were significantly younger (p = 0.00182) and also had a lower TPA compared to the rest (p < 0.001). When analyzing the oblique corridor at the L4-L5 level, we found the following distribution: 0 (n = 30, 18.5%), 1 (n = 64, 39.5%), 2 (n = 48, 29.6%), and 3 (n = 20, 12.3%). Patients with types 2 and 3 were significantly older (p < 0.001). Regarding the morphology of the left psoas muscle, we identified patients with type 1 (n = 61, 37.7%), 2 (n = 7, 4.3%), A1 (n = 65, 40.1%), A2 (n = 24, 14.8%), and A3 (n = 5, 3.1%). Types A2 and A3 had a significantly higher PI compared to type 1 (p < 0.005). A3 was associated with a significantly higher TPA compared to 1, 2, and A1 (p < 0.005). Lastly, types A1 and A3 had smaller corridors than 2 (p < 0.05). Patients with Roussouly 4 had an 83% lower odds ratio of having a larger oblique corridor compared to patients with Roussouly 1 [OR 0.17, 95% CI (0.03 - 0.80), p = 0.027]. On the other hand, patients with psoas type A3 had an 89% lower odds ratio of having a larger oblique corridor compared to those with psoas type 1 [OR 0.11, 95% CI (0.01 - 0.88), p = 0.043]. Finally, we established that for each additional year of age, the odds ratio of having a larger oblique corridor increased by 7% [OR 1.07, 95% CI (1.04 - 1.09), p < 0.001]. Conclusion: This study demonstrates that anatomical changes occur when correlating the type of psoas muscle, oblique corridor, spinopelvic parameters, and age. Understanding these correlations is crucial for the proper treatment planning of our patients.

RF03: SURGICAL COMPLICATIONS IN SPINE

ID: 372

RF038: Early reoperations do not adversely affect long term pain and activity scores in adult spinal deformity patients

Sarthak Mohanty ¹ , Fthimnir Hassan ² , Nathan Lee ³ , Justin Scheer ⁴ , Chun Wai Hung ⁵ , Steven Roth ⁶ , Erik Lewerenz ² , Joseph Lombardi ² , Zeeshan Sardar ² , Ronald A. Lehman ² , Lawrence Lenke ²

¹ Massachusetts General Hospital, Boston, United States,

² Columbia University Irving Medical Center, New York, United States,

³ Midwest Orthopaedics at RUSH, Chicago, United States,

⁴ Cedar Sinai Medical Center, Los Angeles, United States,

⁵ Houston Methodist, New York, United States,

⁶ University of Florida Medical Center, Gainesville, United States

Introduction: Surgery for adult spinal deformity (ASD) is associated with a high rate of complications and subsequent reoperations. The influence of early, successfully managed reoperations on long-term health-related quality of life (HRQoL) remains contentious, highlighting its importance in patient counseling. The purpose of this study is to examine the impact of effectively managed early complications following ASD surgery on two-year (2Y) patient reported outcomes (PROs). Methods: This is a retrospective, single center cohort study of surgically treated ASD patients with at least 2Y of follow-up. Patients underwent posterior spinal fusion (PSF) and met one or more of the following criteria: pelvic incidence-lumbar lordosis mismatch (PI-LL) > 20 degrees, T1 pelvic angle (T1PA) > 30 degrees, sagittal vertical axis (SVA) > 5 cm, or scoliosis > 50 degrees. We stratified patients into two groups: those without readmissions/reoperations (No Reops) and those who underwent early reoperation within six months post-index surgery (Early Reop). An early reoperation was defined as an unplanned return to surgery resulting from complications within six months of the initial ASD correction. Evaluated outcomes comprised 2Y PROs, PRO improvements, and minimum clinically important difference (MCID) attainment. Additionally, Question 22 from the SRS-22r questionnaire, which assesses the likelihood of opting for the same treatment again, was analyzed. A sample size of at least 48 patients was required to detect a 0.1-point difference in PRO improvement with 95% statistical power. Between-group changes in PROs were analyzed using a mixed-effects model for repeated measures. The model included fixed effects for treatment, time (one-year, two-year), and their interaction. Results: 238 patients were included. Of these, 211 (89%) had no No Reops, while 27 (11%) underwent Early Reop. Early reoperations were associated with PJK or DJK (29.63%, n = 8), implant dislodgement (18.52%, n = 5), and pedicle or vertebral fracture (14.81%, n = 4). Other complications, each at 7.41% (n = 2), included painful implants, screw breakage, motor deficits, and spinal cord injury. Between cohorts, there was no significant differences in demographics, operative characteristics, baseline alignment measures, and preop PROs. PRO improvement was not significantly different for SRS Activity (0.67 vs 0.54, p = 0.392), Pain (1.08 vs 0.88, p = 0.291), Appearance (1.35 vs 1.12, p = 0.179), Mental Health (0.36 vs 0.33, p = 0.840), Satisfaction (1.36 vs 0.93, p = 0.098), Total score (0.91 vs 0.74, p = 0.152), and ODI (-17 vs -15, p = 0.564). MCID achievement was comparable for SRS Activity (59% vs 52%, p = 0.536), Pain (74% vs 59%, p = 0.115), Appearance (82% vs 78%, p = 0.269), Mental Health (36% vs 37%, p > 0.999), Satisfaction (82% vs 74%, p = 0.149), and ODI (61% vs 70%, p = 0.403). SRS total score MCID attainment was greater for No Reops Cohort (82% vs 70%, p = 0.048). In addition, a greater proportion of No Reop patients endorsed that they would choose the same operative management (86% vs 70%, p = 0.046) if they had to choose again. Conclusions: Early reoperations within six months after ASD surgery that address the reason for the revision do not adversely affect two-year functional and pain outcomes. However, only 70% would choose the same treatment again, compared to 86% of those who did not undergo a reoperation, albeit less than the rate among uncomplicated cases.

ID: 2629

RF039: Stimulation of the pedicle corridor with an electrical probe. Comparison with direct pedicle screws stimulation and its correlation with medial pedicle breaches in postoperative computed tomography

Lyonel Beaulieu ¹ , Roberto Larrondo ¹ , Sebastian Cabello ¹ , Andre Beaulieu ²

¹ Clinica Universidad de los Andes, Traumatología y Ortopedia, Centro de Columna, Santiago, Chile,

² Hospital del Trabajador, Traumatología y Ortopedia, Santiago, Chile

Introduction: The spine instrumentation with pedicle screws (PS) can compromise adjacent neural structures. The utility of pedicle screw stimulation (PSS) has been described as a tool available during intraoperative neuromonitoring (IONM). Stimulation of the pedicle corridor (SPC) using an electrified probe is a less utilized and studied tool, which could assist in the instrumentation and alert the presence of medial pedicle breaches (MPB) before screw placement, potentially reducing neurological and mechanical risks. The objective of this study is to evaluate the reliability of PSS and SPC with an electrified probe in PS positioning comparing them with the gold standard (postoperative computed tomography (post-op CT) to assess de PS position. Material and Methods: A retrospective review of patients who underwent instrumented posterolateral arthrodesis for lumbar degenerative pathology between January 2017 and December 2019 was conducted. Surgeries were performed by two surgeons of our institution, with screw positioning conducted under anatomical references and fluoroscopic assistance in two planes. IONM was performed by three neurologists from our institution. SPC and PSS were conducted with progressively increasing intensity until a motor response was obtained or reaching the maximum intensity of 12 mAmp in SPC and 30 mAmp in PSS. The results of SPC and PSS were correlated with the post-op CT images for each PS. Sensitivity (Se) and specificity (Sp) were established for different proposed thresholds for each test (SPP and PSS). The electric current intensity values between well-positioned screws and those pedicles that showed MPB were also compared. Results: A total of 304 PS were evaluated between L1 and S1, with 29 of them showing MPB. Four of these patients presented with irritative radicular symptoms, one of which lasted less than 10 days. The remaining patients experienced symptom resolution within 60 days postoperatively, without the need for injections or additional surgeries related to the instrumentation. The well-positioned screws averaged 11.73 mAmp when stimulating the pedicle corridor and 25.69 mAmp when stimulating the screw, while the averages for screws that exhibited medial breaches were 10.41 and 16.24 mAmp, respectively (p = 0.0013 and p < 0.001). ROC curves were modeled for both tests; the area under the curve (AUC) for PPS was 0.5995, whereas the AUC for direct PSC was 0.7935. Establishing a cutoff value of 12 mAmp for screw stimulation increased sensitivity from 37.93 to 44.83% and 41.38% when complemented with pedicle corridor stimulation using cutoff values of 10 and 8 mAmp, respectively. However, utilizing a cutoff value of 15 mAmp for screw stimulation increased sensitivity from 48.28 to 51.72% with corridor stimulation at a cutoff of 10 mAmp, without increasing sensitivity at other thresholds. Conclusion: Both SPP and PSC demonstrate low sensitivity for detecting malpositioned screws with medial breaches; however, direct stimulation of the screw seems to show a greater impact in its association with MPB on postoperative CT. Adding SPC to screw stimulation does not significantly increase diagnostic sensitivity.

ID: 1234

RF040: Spinal alignment and adjacent segment disease in short-segment lumbosacral fusion

Giuseppe Loggia ¹ , Mazda Farshad ¹ , Moritz Jokeit ¹ , Jonas Widmer ¹ , Stefani Dossi ¹ , Marco Burkhard ¹

¹ Balgrist University Hospital, Zurich, Switzerland

Introduction: This study examined the association between global and distal lumbar spinopelvic alignment (SPA) and adjacent segment disease (ASD) development necessitating revision surgery in long-term follow-up after short-segment lumbosacral fusion. Secondary objectives were ultimate postoperative patient reported outcome measures (PROMs) in dependance of ASD development. Material and Methods: This retrospective cohort study analyzed patients who underwent L4-S1 spinal fusion from 2003-2015, with a minimum follow-up of 5 years. Patients requiring ASD revision surgery (ASD group) were compared to controls. Pre- and postoperative standing radiographs were annotated and the following global lumbar SPA parameters analyzed: Pelvic incidence (PI), sacral slope (SS), pelvic tilt (PT), lumbar lordosis (LL), PI-LL-mismatch, lumbar pelvic angle (LPA). Additionally, the following distal lumbar SPA parameters were analyzed: Distal lordosis (DL) between L4-S1, lordosis distribution index (LDI = DL/LL), PI-DL-difference, DL-PI-ratio, adjacent segment lordosis (ASL). The Oswestry Disability Index (ODI) and the 5-level EQ5D (EQ5D5L) were assessed via a telephone interview. Results: Eighty-six patients with a mean follow-up of 12 ± 4 years had a 29.1% incidence (n = 24) of ASD revision surgery. No significant differences in pre- and postoperative global lumbar SPA were found. PI (53.6° vs. 59.6°) and preoperative SS (34.9° vs. 40.3°) trended to be lower in the ASD group, although non-significant. Distal lumbar SPA parameters did not differ from pre- to postoperative between groups. Patients needing ASD revision had higher ultimate ODI scores (28 (IQR = 15-42) vs. 12 (IQR = 4-28); p = 0.011) and lower EQ5D5L scores (70 (IQR = 53-83) vs. 85 (IQR = 70-90); p = 0.019). Conclusion: SPA was not associated with ASD revision surgery in short-segment lumbo-sacral fusions in a long-term follow-up, suggesting other factors may be more influential in long-term outcomes. Patients requiring ASD revision had worse postoperative PROMs, underlining the importance of ASD prevention.

ID: 1789

RF041: Prolonged operative time significantly impacts on the incidence of complications in spinal surgery

Annalisa Monetta ¹ , Cristiana Griffoni ¹ , Luigi Falzetti ¹ , Gisberto Evangelisti ¹ , Luigi Emanuele Noli ^1,2 , Giuseppe Tedesco ¹ , Carlotta Cavallari ¹ , Stefano Bandiera ¹ , Silvia Terzi ¹ , Riccardo Ghermandi ¹ , Marco Girolami ¹ , Valerio Pipola ¹ , Alessandro Gasbarrini ¹ , Giovanni Barbanti Bròdano ¹

¹ IRCCS Istituto Ortopedico Rizzoli, Department of Spine Surgery, Bologna, Italy,

² ISNB Istituto delle Scienze Neurologiche di Bologna, Bologna, Italy

Introduction: In spinal surgery adverse events (AE) and surgical complications (SC) significantly affect patient’s outcome and quality of life. The duration of surgery has been investigated in different surgical field as risk factor for complications. The aim of this study is to analyze the correlation between operative time and adverse events in spinal surgery. Material and Methods: We retrospectively analyzed data collected prospectively in a cohort of 336 patients surgically treated for spinal diseases of oncological and degenerative origin in a single center, between January 2017 to January 2018. Demographics and clinical data were collected. Adverse events were classified using Spinal Adverse Events Severity System version 2 (SAVES-V2) capture system. Focusing on degenerative patients, bivariate analysis and univariate logistic regression were used to determine the association between operative time and complications. Results: A total of 105/336 patients experienced an AE related to surgery, respectively 38% in the oncological group and 28% in the degenerative group. The average age at surgery was 60.3 years (SD 17.1) and the mean operative time was 164.8 ± 138 minutes. A total of 206 adverse events (30 intraoperative, 135 early postoperative and 41 late postoperative AEs) were recorded. Early post-operative complications accounted for the most recorded AEs (55.5% in the oncological group and 73.2% in the degenerative group). Univariate logistic regression analyses confirmed that operative time correlated with increased risk of intra-operative (p-value = 0.0008), early post-operative (p-value < 0.001) and late post-operative (p-value < 0.001) adverse events. Conclusion: This study highlights the strong correlation between the occurrence of adverse events in spinal surgery and prolonged operative time and suggests that efforts should be made to minimize the duration of surgical procedures while prioritizing patient’s safety, without compromising the technical achievement of the procedure.

ID: 1596

RF042: DNA-based epigenetic age is a better predictor of complications than chronological age and frailty

Quante Singleton ¹ , Rohit Bhan ¹ , Yu Zhang ¹ , Christopher Diaz ¹ , Nisha Kale ¹ , Christopher Ames ² , Bo Zhang ¹ , Michael Kelley ¹ , Nicholas Pallotta ¹ , Brian Neuman ¹

¹ Washington University in St. Louis, Orthopaedic Surgery, St. Louis, United States,

² University of California, San Francisco, Neurosurgery, San Francisco, United States

Introduction: The prevalence of symptomatic adult spinal deformity (ASD) is increasing with an aging population, with surgical complication rates of 37%-71%. Prior studies propose increased chronological age (CA) and frailty as risk factors for complications, but this may be due to differences in epigenetic age (EA), suggestive of a patient’s underlying biological reserve in response to stress. DNA methylation assays have emerged as the gold-standard for determining EA. We aim to investigate the relationship between EA and complications within 6 weeks after ASD surgery. Materials and Methods: ASD patients provided blood samples on the day of surgery. DNA methylation of peripheral blood mononuclear cells (PBMCs) was analyzed using IlluminaEpic v2.0. EA was calculated using the Horvath biological clock (DNAmAge) algorithm. Edmonton Frailty Index (EFI) was collected at the pre-operative visit. EFI, EA, and CA were assessed as risk factors for complications reasonably related to a patient’s biology. Parametric and non-parametric analyses were used to assess significance. Results: 30 surgical ASD patients were enrolled. 15 (50%) were revisions. 21 patients (70%) received all-posterior and 9 (30%) underwent anterior-posterior surgery. 7 (23%) received a three-column osteotomy and average levels fused was 11.9 (SD = 3.7). Complications were pulmonary emboli (N = 2), death (N = 1), reoperation for dehiscence (N = 1), altered mental status (N = 5), and acute kidney injury (N = 4). There were no 30-day readmissions. Mean EA and CA were significantly different (71.2 vs 68.4, p = 0.009). For patients who experienced a post operative complication (N = 14, 47%) there was an association with EA > CA (86%) compared to CA > EA (14%, p = 0.038). The difference between EA and CA (EA-CA) was greater in patients that had a complication (5.07 vs 0.87, p = 0.029). There was no association of EFI for frailty between complication groups. Between complication groups, there was no difference in mean CA (67.7 vs 69.0, p = 0.596), EA (73.0 vs 69.7, p = 0.12), or EFI (4.3 vs 3.7, p = 0.468). Conclusion: Preliminary findings suggest EA > CA has greater association with perioperative complication after ASD surgery than EFI, EA, or CA alone. Further studies with more patients are warranted to investigate epigenetic stressors linked to changes in EA. These patient-specific factors can be used to improve risk-stratification in ASD surgeries.

ID: 843

RF043: Metallosis in posterior lumbar fusion: corrosion susceptibility based on rod metal type and bending method

Samantha Corman ^1,2 , Nicole DeVries Watson ² , Douglas Fredericks ² , Catherine Olinger ²

¹ University of Iowa, Carver College of Medicine, Iowa City, United States,

² University of Iowa, Orthopedics and Rehabilitation, Iowa City, United States

Introduction: Metallosis is a rare but significant adverse event associated with metal on metal implants, caused by metal debris in the periprosthetic tissue with resultant type IV hypersensitivity and potential for implant failure. In the context of instrumented spinal fusions, there is insufficient understanding of implant qualities that affect metallosis. Two factors of interest are the metal type and the presence of notches, formed by manually bending rods. In this study, we investigate how rod material (titanium alloy vs cobalt chromium alloy) and bending method (pre-bent vs surgeon-bent) affects production of metal debris in Posterior Lumbar Fusions (PLFs) through a novel mechanical test. Material and Methods: Standard PLF rods and screws were used to compare wear using a modified ASTM F1717 protocol. Four groups were tested, with 5 bilateral setups per group (n=10 samples each): Surgeon-bent Cobalt Chromium Alloy Rods (SB CoCr), Pre-bent Cobalt Chromium Alloy Rods (PB CoCr), Surgeon-bent Titanium Alloy Rods (SB Ti), Pre-bent Titanium Alloy Rods (PB Ti). Titanium alloy screws and set screws were used for all constructs. Implants were wrapped with LRS-soaked cotton to enable debris collection. Implants underwent 3 million cycles of compression in force control between -5N and -155N at 5Hz with simultaneous axial rotation in rotation control (± 1.50°) at 3Hz for 1.8 million cycles. Cotton was removed and dissolved to produce corrosion samples. Implants were deconstructed and rinsed in LRS following testing to obtain secondary corrosion samples. Metal debris was dissolved, and samples were analyzed using Inductively Coupled Plasma Mass Spectrometry (ICP-MS) to measure the total mass of Ti, Co, and Cr. Stereomicroscopic exam of the implants localized wear. ANOVA will be used to compare metal debris between groups. Results: Preliminary results compare PB CoCr (n = 6) and SB CoCr groups (n = 6). Preliminary T tests were performed, and a statistically significant difference was found in chromium detected in each group (PB CoCr mean = 156.34 µg, sd = 53.16 µg; SB CoCr mean = 247.71 µg, sd = 78.22 µg). Cotton samples covering cobalt chromium rods held a comparatively low amount of titanium (PB CoCr mean = 4.66 µg, sd = 0.206 µg; SB CoCr mean = 3.03 µg, sd = 3.06 µg), serving as a negative control and validating the protocol. Passive corrosion control trials produced no detectable wear, supporting that wear occurred through fatigue-corrosion testing. Conclusion: There is no ASTM standard for assessing corrosion susceptibility in spinal implants. Previous studies have yielded few findings from titanium and cobalt chromium alloys. This project creates an updated fatigue-corrosion testing model to match modern materials. It is unique in the addition of axial rotation, to better mimic in vivo forces and allow for titanium and cobalt chromium alloys to be quantitatively compared. This study also assesses corrosion susceptibility based on bending method, a variable that has not been previously reported on. This project allows quantitative comparisons of notching and rod metal type on corrosion and fretting, clarifying factors that affect risk of metallosis in spine constructs. This information will help with clinical decision making, reducing the risk of metallosis-related complications.

ID: 667

RF044: Rate of surgical site infection following spinal surgery and effectiveness of preoperative intranasal photodynamic disinfection therapy and chlorhexidine gluconate body wipes prophylaxis: a quality of care study

Louis Carrier ¹ , Ariane Paquette ¹ , Bernard LaRue ¹ , Jocelyn Blanchard ¹

¹ Université de Sherbrooke, Département de Chirurgie, Faculté de Médecine et des Sciences de la Santé, Sherbrooke, Canada

Introduction: Surgical site infections (SSI) following spine surgery occur in 1-16% of cases and can lead to morbidity and increased hospital costs. To reduce the incidence of spinal SSI, combined use of preoperative intranasal photodynamic disinfection therapy (nPDT) and chlorhexidine gluconate body wipes (CHG) can be utilized. This prophylaxis was found to significantly decrease SSI rates in spine patients, regardless of the procedure. Material and Methods: In this retrospective quality of care study at our center, we aimed to determine the rate of SSI following any spine surgeries before and after the introduction of nPDT-CHG prophylaxis on April 2023. All adult patients who had spinal surgery from January 2021 to April 2024 were included, regardless of the procedure or the indication for surgery. Patients who did not benefit from postoperative follow-up were excluded. The secondary outcomes were to (1) determine the compliance rate in our center following elective and urgent spinal surgeries and (2) evaluate the effectiveness of nPDT-CHG prophylaxis for reduction in spine SSI in the per-protocol population. Results: 246 patients were included, of those 69 (28%) and 177 (72%) patients had surgery before and after April 2023, respectively. Demographic data showed no significant difference between the two groups. The SSI rate was 5.8% in the first group compared to 3.95% in the second group (p = 0.508). In the second group, compliance to nPDT-CHG prophylaxis was at 58,2% [50.6% - 65.5%] amongst all patients, while it was at 81% during elective procedures and at 8.9% during urgent procedures (p < 0.001). When comparing patients who had the prophylaxis (103 patients) to those who did not (143 patients), the SSI rate was 0.97% compared to 6.99%, respectively (p = 0.028). Looking at the elective population, the deep wound infection rate was 0% compared to 5.9% (p = 0.025) in patients who had the prophylaxis and those who did not, respectively. Conclusion: No significant difference was found between the SSI rate following spine surgery before and after the introduction of nPDT-CHG prophylaxis in our center. However, the compliance rate to the prophylaxis was lower than expected, and when comparing SSI rates between patients who had the prophylaxis to those who did not, a significant decrease was found. Deep wound infection rate was also significantly lower when patients had the prophylaxis following an elective procedure. This reinforces the known benefits of this prophylaxis in spinal SSI prevention.

ID: 402

RF045: Effects of intraoperative hypothermia in posterior lumbar fusions

Erin Welby ¹ , Alex Tang ² , Edward DelSole ³ , Tan Chen ⁴

¹ Geisinger Commonwealth School of Medicine, Scranton, United States, ² Geisinger Health, Orthopaedic Surgery Northeast Residency, Wilkes-Barre, United States, ³ Keystone Spine & Pain Management Center, Wyomissing, United States, ⁴ Geisinger Health, Department of Orthopaedic Surgery, Wilkes-Barre, United States

Introduction: Intraoperative hypothermia (T < 36°C) has been well established to increase surgical complications, blood loss, and need for transfusion in orthopaedic arthroplasty literature. There is limited data investigating the perioperative effects of hypothermia in spine surgery. The purpose of this study was to (1) compare the demographics of lumbar fusion patients who did and did not develop complications, and (2) characterize the effects of intraoperative hypothermia on blood loss and postoperative complications. Material and Methods: Retrospective analysis was performed identifying adult patients undergoing elective posterior lumbar fusion for degenerative pathology from 2022 to 2024. Patient demographics, intraoperative blood loss, perioperative temperature records and postoperative complications were collected. Descriptive and inferential statistics were performed. Results: A total of 293 patients were collected, of which 35 (11.9%) developed a postoperative complication (Comp) and 258 (88.0%) had uneventful recoveries (No-Comp). Demographic analysis demonstrated the Comp cohort had higher ASA scores (2.77 vs. 2.59, p = 0.019), higher Charlson Comorbidity Index scores (3.1 vs. 2.2, p = 0.009), and greater number of fusion levels (2.2 vs. 1.7, p = 0.017). No cohort differences were found for patient BMI, age, ethnicity, and smoking status. Cohort analysis demonstrated no difference in intraoperative hypothermic time (Comp: 94.3min, No-Comp: 96.3 min, p = 0.897), temperature fluctuation (Comp: 1.0°C, No-Comp: 1.2°C, p = 0.132), mean temperature (Comp: 36.0°C, No-Comp: 36.0°C, p = 0.965), length of surgery (Comp: 209.0min, No-Comp: 206.2, p = 0.857), and estimated blood loss (Comp: 431.0ml, No-Comp: 340.1ml, p = 0.182). On univariate and multivariate analysis, EBL and complications were influenced by number of fusion levels but not by hypothermic time (p < 0.05). Each additional fusion level corresponded to a 65.8ml increase in blood loss and 1.39 times the odds of complications. Conclusion: Intraoperative hypothermia does not influence postoperative complications or blood loss following posterior lumbar fusion, going against previous published literature in non-spinal orthopaedic subspecialties. Each additional fusion level corresponded to a 65.8ml increase in blood loss and 1.39 times the odds of complications.

ID: 371

RF046: The impact of CSF leaks on 90 day reoperation rates for recurrent CSF leakage among adult spinal deformity patients

Erik Lewerenz ¹ , Fthimnir Hassan ¹ , Lawrence Lenke ¹

¹ Columbia University Irving Medical Center, New York, United States

Introduction: A not too uncommon intraoperative complication in adult spinal deformity (ASD) surgery is a dural tear accompanied by cerebral spinal fluid (CSF) leakage. The methods to rectify this complication vary depending on surgeon preference. Further CSF leakage following discharge in this patient population does occur, typically induced by signs of worsening headaches when standing and improvement when laying down. However, the incidence and reoperation rates are of recurrent CSF leakage and repair following ASD surgery is unknown. The purpose of this study is to determine the incidence rate and differences in treatment associated with recurrent CSF leakage and repair. We hypothesize that ASD patients who incur an intraoperative CSF leak rarely experience further CSF leakage requiring a return to the operating room (RTOR) due to proper sealing techniques and vigilant postoperative monitoring. Methods: This is a retrospective, single surgeon case series of ASD patients who experienced CSF leaks intraoperatively. The primary outcome of interest was the incidence rate of recurrent CSF leakage and repair following ASD surgery. The secondary outcome was whether differences in treatment are associated with recurrent CSF leakage. Patients were dichotomized to whether they returned to the operating room for further CSF leakage (RTOR) or not (NROTR). Patient, operative, and radiographic characteristics were analyzed and compared through bivariate analyses to assess differences in treatment. Results: 624 consecutive ASD patients were analyzed with 116 (18.5%) patients found to have experienced an intraoperative CSF leak. 5/116 (4.3%) of these patients RTOR for recurrent CSF leakage repair (RTOR = 5, NRTOR = 111). Both groups were comparable in age, BMI, gender, number of revision cases, preoperative diagnosis, and presence of any form of stenosis (p > 0.05). Operatively, both groups were comparable in EBL, transfusion rates, operative time, instrumented levels, rates of pelvic fixation, and total osteotomies performed, including three-column osteotomies (p > 0.05). Repair methods, including Gore-Tex suture, DuraSeal, DuraGen, Surgicel, and muscle grafts between each group were also similar. Postoperative care, including nights spent in the ICU, total number of hours kept horizontal following the initial intraoperative repair, and lengths of stay were similar. Postoperatively, both groups differed radiographically where the RTOR was found leaning forward in the sagittal plane more on discharge X-rays than NRTOR (CrSVA-H: 7.5 vs 4.3 cm, p = 0.0404) and (SVA 5.6 vs 2.3 cm, p = 0.0156), both of which were statistically significant. None of the RTOR patients had any further surgery for CSF leakage following the repair. Conclusions: Among ASD patients who experienced an intraoperative CSF leak, 4.3% (5/116) of these patients had a RTOR for further leakage repair which was successful. There were very few differences between the two groups who did vs. did not RTOR for further leakage when analyzing preoperative, intraoperative, and postoperative factors. Thus, repair of CSF leaks with a suture, sealant and graft, and at least 24 hours of flat bedrest with close monitoring post-surgery appears sufficient in the vast majority of cases to prevent further leak.

ID: 1443

RF047: Predicting surgical site infections in lumbar discectomy and laminectomy procedures: a cutting-edge algorithmic approach by incorporating ensembled stacking into the current state-of-the-art for automated machine learning

Ali Haider Bangash ¹ , Rose Fluss ^1,2 , Sertac Kirnaz ² , Saikiran Murthy ² , Yaroslav Gelfand ² , Reza Yassari ² , Rafael De La Garza Ramos ^1,2

¹ Spine Research Group, Montefiore Medical Center, Albert Einstein College of Medicine, Bronx, NY, United States, ² Department of Neurosurgery, Montefiore Medical Center, Albert Einstein College of Medicine, Bronx, NY, United States

Introduction: Surgical site infections (SSIs) are a significant complication following spinal procedures, with an incidence rate of approximately 1.5%. These postoperative infections can lead to prolonged hospital stays, increased healthcare costs, and potentially life-threatening consequences. Accurate prediction of SSI risk is crucial for implementing preventive measures and optimizing patient management. However, traditional statistical models have limitations in capturing complex, nonlinear relationships inherent in heterogeneous patient population datasets. This study aimed to develop a cutting-edge algorithmic model for predicting SSIs following lumbar discectomy and laminectomy by incorporating ensembled stacking techniques into automated machine learning (aML) approaches. Material and Methods: A comprehensive dataset from a multicenter surveillance study on SSIs following lumbar laminectomy and/or discectomy was utilized. After data preprocessing, the dataset was split into training (70%) and testing (30%) sets. Nine algorithms, including eXtreme Gradient Boosting (XGBoost), Neural Networks, CatBoost, Light Gradient Boosting Machine (LGBM), and Random Forest, were adopted with hyperparameter tuning. Ensembling of the developed models was carried out, followed by stacking. The macro-weighted average Area Under the Receiver Operating Curve (mWA-AUROC) was used to evaluate the discriminating ability of the models. Accuracy, sensitivity and specificity metrics were also considered. Results: The dataset consisted of 4,027 patients (Mean age: 59 years; Female: 31%). Only lumbar spine was involved in 75% (n = 3020) cases with 60% (n = 2416) patients being managed with discectomy. 0.65% (n = 26) patients developed an SSI. A stacked ensemble algorithmic model, comprising a stacked XGBoost model and an ensemble of XGBoost, Neural Network, CatBoost, LGBM, and Random Forest models, predicted SSI with an mWA-AUROC of 0.994, an accuracy of 98.7%, a sensitivity of 90% (95% CI: 68.30% - 98.77%) and a specificity of 98.81% (95% CI: 98.15% - 99.28%). The top-weighted constituent model, XGBoost-20, identified operative time, smoking status, and patient age as the most influential predictors of SSI. Conclusion: This study presents a novel algorithmic approach that integrates ensembled stacking techniques into the current state-of-the-art for aML to predict SSIs following lumbar discectomy and laminectomy procedures. The performance of the stacked ensemble model, with its high discriminative ability and robust evaluation metrics, highlights its potential to serve as a valuable clinical decision support tool, enabling more informed decision-making, optimized resource utilization, and enhanced patient outcomes. The study addresses a critical need for accurate SSI prediction and demonstrates the potential of advanced machine learning techniques to revolutionize surgical risk assessment and preventive strategies. Future research should focus on validating the model's performance in diverse settings, exploring its applicability to other spinal procedures, and evaluating its integration into clinical practice.

ID: 1126

RF048: Neurological complications associated with anterior lumbar interbody fusion: a systematic review

Takeshi Fujii ^1,2 , Rakesh Kumar ¹ , Jihun Cha ³ , Aiyush Bansal ¹ , Venu Nemani ¹ , Jean Christophe Leveque ¹ , Rajiv Sethi ¹ , Philip Louie ¹

¹ Virginia Mason Medical Center, Seattle, United States,

² Keio University, Tokyo, Japan,

³ Washington State University, Seattle, United States

Introduction: Anterior lumbar interbody fusion (ALIF) is increasingly utilized to treat pathologies of the lumbosacral as it provides a substantial correction of lumbar lordosis and achieve appropriate sagittal alignment. While multiple studies have reported perioperative complications including vascular, ureteral, visceral, and neurologic injury associated with ALIF, there is a paucity of literature reporting data on neurological complications in ALIF to date. The aim of this article is to investigate the incidence and risk factors of neurological complications in ALIF through a systematic review of existing literature. Materials and Methods: A systematic review of the literature was designed for articles published between January 2000 and June 2024. Literature search was conducted to identify articles reporting neurological complications associated with ALIF. Studies evaluating outcomes following lateral approach, abstracts without full text available, and literature written not in English were excluded. For outcome measures, we collected information on the type of neurological complications and their incidence. Results: A total 28 articles met final inclusion criteria and reported neurological complication rates in patients who underwent ALIF. Neurological complications associated with ALIF included nerve root injury (radiculopathy and neurological deficit) and sympathetic nerve injury (retrograde ejaculation and post-sympathectomy dysfunction). The overall rate of neurological complication associated with ALIF ranged from 1.8% to 9.4%, While the rates of nerve root injury in lumbar spine diseases were 0.1-3.8%, the rates were higher in the studies including adult spinal deformity (ASD), ranging from 7.1% to 38.4%. When focusing on the ALIF at L5-S1, L5 nerve root injury can be caused by a foraminal stenosis due to pincer mechanism and nerve root stretch secondary to overdistraction with hyperlordotic. 3 studies reported reoperation rates related to nerve root injuries following hyperlordotic ALIF at L5-S1, with these rates ranging from 1.8% to 8.3%. Reduced neurological complications were reported in the procedures using a mini-open, retroperitoneal approach, utilizing an experienced access surgeon and neuromonitoring, and avoiding recombinant human bone morphogenetic protein (rhBMP). Conclusion: While the overall rate of neurological complications associated with ALIF were relatively low, ALIF for ASD reported higher incidence of nerve root injury. Given that certain patients required revision surgery following hyperlordotic ALIF, careful surgical planning is essential to mitigate the risk of these complications in the correction surgery.

ID: 240

RF049: Laminectomy with fusion for degenerative cervical myelopathy is associated with higher early morbidity and risk of perioperative complications compared to laminectomy alone

Abhinav Sharma ¹ , Paramveer Birring ¹ , Manaav Mehta ² , Nicole Goldenhersh ¹ , Frederik Heath ¹ , Jason Liang ¹ , Maziar Moslehyazdi ¹ , Amanda Tedesco ¹ , Nischal Acharya ³ , Michael Steinhaus ⁴ , Hao-Hua Wu ¹ , Sohaib Hashmi ¹ , Don Park ¹ , Yu-po Lee ¹ , Zorica Buser ⁵ , Nitin Bhatia ¹

¹ University of California, Irvine, Department of Orthopaedic Surgery, Orange, United States,

² University of Massachusetts Chan Medical School, Worcester, United States,

³ University of California, Irvine, Department of Neurological Surgery, Orange, United States,

⁴ The Spine Institute, Salt Lake City, United States,

⁵ NYU Grossman School of Medicine, Department of Orthopedic Surgery, New York, United States

Introduction: The choice of decompression with fusion or decompression alone for management of degenerative cervical myelopathy (DCM) is controversial. Advantages of fusion include potentially reduced rates of instability leading to postlaminectomy kyphosis and late neurologic deterioration; however, fusion has also been shown to be associated with increased rates of postoperative complications, length, complexity, and cost of surgery. The purpose of this study was to investigate differences in perioperative outcomes of DCM patients treated with decompression and fusion versus decompression alone. Material and Methods: Inclusion criteria were adults ≥ 18 years of age who presented with spondylosis with cervical myelopathy (ICD10: M47.12) or spinal stenosis of the cervical region (ICD10: M48.02) who had undergone laminectomy (CPT 63001, 63015, 63045) with or without fusion (CPT 22600) from 2015 to 2020 included in the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database. 30-day post-op complication data and American Society of Anesthesiologist (ASA) physical status classification were evaluated through Chi-square and analysis of variance (ANOVA) tests, with results further stratified according to ASA classification using ANOVA with post-hoc Tukey and Chi-square analyses. Complications consisted of estimated 30-day mortality and morbidity, reintubation, unplanned reoperation, unplanned readmission, and length of stay in the hospital (days), superficial infection, deep wound infections, sepsis, bleeding requiring transfusions, deep vein thrombosis, pulmonary embolism, urinary tract infection, renal insufficiency, renal failure, myocardial infection, cardiac arrest, and stroke. Results: 6,412 patients met inclusion criteria. Patients undergoing decompression with fusion had higher mean morbidity (estimated probability 0.073 vs. 0.064, p < 0.001), unplanned reoperations (4.2% vs. 2.7%, p < 0.002), unplanned readmissions (7.6% vs. 6.3%, p < 0.014), mean length of stay (5.0 ± 8.9d vs. 3.4 ± 7.2d, p < 0.001), deep wound infections (0.8% vs. 0.4%, p < 0.022), and bleeding risk necessitating transfusion (3.8% vs. 1.6%, p < 0.001). Stratification by ASA scores demonstrated an overall higher rate of 30-day postoperative complications associated with increasing ASA score for both cohorts, with a correspondingly greater increase in complications in the fusion cohort relative to decompression alone patients within each ASA group. Conclusion: In patients undergoing surgery for DCM, decompression with fusion is associated with higher estimated morbidity, unplanned reoperations and readmissions, and risk of immediate postoperative complications, including bleeding risk necessitating transfusion and deep wound infections, as well as longer length of stay relative to decompression alone within the first 30-days postoperatively. Decompression alone should be considered as treatment for DCM, particularly for patients with higher ASA scores and risk for postoperative complications.

ID: 2812

RF050: Fusion mass fractures vs pseudarthrosis in rod fractures following thoracic to pelvis fusion surgery for adult spinal deformity

Eliana Seider ¹ , Lauren Daunt ¹ , Vanessa Vashishth ¹ , Aazad Abbas ¹ , Stephen Lewis ¹

¹ University of Toronto, Toronto, Canada

Introduction: Rod fractures are a major mechanical issue in adult spinal deformity (ASD) surgery patients and is generally attributed to pseudarthrosis. While pseudarthrosis is the prevalent mode of failure, there is potential for a fracture of the fusion mass to occur leading to a rod fracture. The primary objective of this study was to determine whether fusion mass fractures in the presence of a solid posterior fusion mass is an identifiable cause of rod fracture. Material and Methods: A retrospective chart and radiograph review of 200 consecutive ASD cases with fusion from the thoracic spine to the pelvis from a single fellowship-trained spine surgeon was performed. Patients with complete charts and imaging that included post rod fracture CT scans available on the hospital system were included. Demographic and clinical variables such as age, body mass index (BMI), and presence of neurodegenerative disorders were collected. Fusion mass fractures were defined as transverse fractures of the fusion mass that were not in the region or orientation of the facet joints with no identifiable defect in the fusion mass. Pseudoarthrosis was defined as defects in the fusion mass that followed the orientation of the facet joints. Disc height in millimeters and the presence or absence of an interbody cage were documented. Continuous variables were summarized with mean and standard deviation (SD), and categorical variables were summarized using counts (N) and percentages (%). Radiographs and CT scans were reviewed by 4 observers and etiology of the rod fracture determined by consensus. Results: 161 patients were included, with 20 patients undergoing revision surgery for rod fractures. Seven patients experienced fusion mass fractures, while 13 had pseudarthrosis. Transverse rod fractures were frequent in patients with disc heights > 10 mm at the fracture site (6/7). There were no interbody cages placed at the fractured level. In contrast, 92.3% of patients with pseudarthrosis had a disk height < 10 mm at the fracture site, and 23.1% had cages placed. Age, sex and BMI did not correlate with whether a pseudarthrosis or fusion mass fracture occurred. Rod material and length varied, with higher use of cobalt chrome rods in transverse fracture patients. Fusion mass fracture cases occurred at more proximal levels with 5/7 (71%) occurring between L2 and L4 while 10/13 (77%) of pseudarthrosis cases occurred between L3 and S1. All patients had 2 rod constructs, and all procedures were performed through single stage posterior surgeries. Conclusion: This study highlights that fusion mass fractures, as opposed to pseudarthrosis, is a proven phenomenon that occurred in 35% of rod fracture cases involving patients undergoing posterior-only long fusions for ASD with 2 rod constructs. Of the cases with fusion mass fractures, 6/7 occurred at levels with disc heights > 10 mm and none of these levels had interbody fusions. This suggests that motion occurring in the mobile anterior column occurs even in the presence of a solid posterior fusion and can lead to fusion mass fractures. Anterior column support and multi-rod constructs may be protective in preventing fusion mass fractures.

ID: 1492

RF051: Reoperation rates after lumbar discectomy in pediatric patients

Andy Liu ¹ , Suhas Etigunta ¹ , Adeesya Gausper ¹ , Karim Shafi ¹ , Kenneth Illingworth ¹ , David Skaggs ¹ , Alexander Tuchman ¹ , Corey Walker ¹

¹ Cedars Sinai, Spine Department, Beverly Hills, United States

Introduction: Lumbar disc herniation (LDH) is uncommon in the pediatric population but can cause significant low-back or radicular pain, and at times, neurological deficits. LDH is characterized by displacement or rupture of the soft tissue content of the intervertebral disc beyond the fibrous outer ring, which may result in compression of adjacent neural structures. Outcomes following lumbar discectomy in the pediatric population is less studied than for adults. We aimed to study discectomy operations in pediatric patients with hopes of defining long-term reoperation rates to provide insight into surgical outcomes that may inform clinical decision-making and patient counseling. Methods: A national insurance claims database (PearlDiver) was queried to identify pediatric patients (< 21 y.o.) who underwent discectomy. Procedures were characterized by demographics features including age of patient, year, and location. Reoperations (discectomy, re-exploration discectomy, fusion, and laminectomy) included any operation occurring within 5 years of the initial discectomy. A subsequent parallel analysis looked at reoperations following re-exploration discectomies. Kaplan Meier survival and cox proportional regression analyzed factors impacting survival post primary discectomy. Results: 4,410 primary discectomy patients were identified. Of these patients, 11.8% underwent reoperation within 5 years of the initial discectomy. The incidence of discectomy operations increased with patient age, with only 11 patients receiving a discectomy under the age of 10 to 1,863 patients in the 20-21 age range. The rate of reoperation was highest within the first-year post-discectomy, with nearly half of reoperations occurring in this time. Specifically, reoperation rates were 2.3% at 3 months, 3.5% at 6 months, 5.5% at 1 year, 7.3% at 2 years, and 11.8% at 5 years. Among the reoperations, the most common procedure was another discectomy. For parallel analysis a total of 290 pediatric patients were identified undergoing a revision/re-exploration discectomy procedure. The reoperation rates following these revision operations were 2.4% at 3 months, 3.8% at 6 months, 6.2% at 1 year, 9.7% at 2 years, and 13.8% by 5 years, suggestion only a slightly high risk of third reoperation in patients with reoperations for reherniation. However, fusion was the most common procedure following a failed revision discectomy (42% at 5 years). The Kaplan-Meier survival analysis similarly showed most procedures occurred in the first 3 years, with obesity and ECI inversely correlated with survival. Conclusion: Overall, pediatric reoperation rates following discectomy are 11.2% in this study, similar to prior adult literature (12.2%) (Heindel et al. 2017). This informs expectations in patients under 21 years of age needing surgery for LDH. Obesity and ECI significantly increase risk of reoperation and should inform patient counseling. In patients with a reherniation requiring revision discectomy, it seems that the rate of third reoperation follows that for the index procedure, but should it be required, most of the time it will be a spinal fusion. This study provides real world, large scale data that may guide surgeons caring for pediatric patients undergoing microdiscectomy.

ID: 2670

RF052: Impact of wound drainge on the early revision rate in posterior spinal fusion surgery - a prospective randomized multicenter study

Klaus Schnake ^1,2 , Denis Rappert ¹ , Olga Cheremina ¹ , Alexander Hammer ^1,3

¹ Malteser Waldkrankenhaus St. Marien, Center for Spinal and Scoliosis Surgery, Erlangen,

² Paracelsus Medical University, Department of Orthopedics and Traumatology, Nuremberg, Germany,

³ Paracelsus Medical University, Department of Neurosurgery, Nuremberg, Germany

Introduction: It is not clear whether wound drainage has a significant protective impact in posterior thoracolumbar spinal fusion surgery. Especially concerning revision surgery and length of stay (LOS) the effect of wound drainage is lacking. We analyzed the effect of wound drainage on the revision rate and the LOS in a collective of posterior thoracolumbar spinal fusion surgery up to 4 segments. Material and Methods: In this prospective randomized multicenter study 281 patients over a period of 29 months with a follow-up of 3 months were included. Indications for an open, posterior instrumented, thoracolumbar spondylodesis with pedicle screws over 1-4 segments with or without history of previous surgery at the affected levels were the inclusion criteria. Dural tear, unstable fractures, pregnancy, known coagulation disorders, cognitive impairment Infections (e.g. spondylodiscitis), inflammatory diseases and tumours, multiple injuries, polytrauma and no possibility for follow-up examination were the exclusion criteria. One subfascial drainage with and one subcutaneous without negative pressure were placed and later removed after a minimum of 2 and a maximum of 4 days, depending on the amount of drain volume. Categorical variables were analyzed with the Chi-Square test and continuous variables with the Mann Whitney-U-test after exclusion of a normal distribution in the Kolmogorow-Smirnow-Test. Regression analysis was performed in order to detect factors modifying the revision rate and LOS. Results: 281 of 314 patients were available (89.5%, mean age 63 years ± 13.2, m: 45.9%, f: 54.1%) for the final analysis after applying the exclusion criteria. Patients with drainage had a significant lower early revision rate (14 of 138; 10.1%) in comparison to patients without drainage (32 of 143, 22.4%) in the univariate analysis in the Chi-Square test (OR 2.55; 95% CI 1.29-5.03; p = 0.0056). Early revision surgery (≤ 3 months) included implant related (7 of 46; 15.2 %), infection related (27 of 46; 58.7 %) or hematoma related early revision surgery (12 of 46; 26.1%). The usage of a drainage (OR 0.36; 95% CI 0.17-0.74; p = 0.0053) and a low body mass index (BMI) (OR 1.09; 95% CI 1.02-1.16; p = 0.067) were the significant main predictors for the avoidance of revision surgery. The length of stay was not influenced significantly by the application of a wound drainage (with drain: 11.2d ± 5.9d); without drain 11.6 ± 6.8d; p = 0.90; Mann Whitney-U-test). In multivariate regression analysis early revision surgery (p < 0.0001) and an increasing number of segments (p < 0.0001) but not the usage of a drainage (p = 0.14) were factors significantly predicting LOS. Conclusion: Early revision can be avoided by the usage of wound drainage which significantly decreases the early revision rate while not increasing the LOS in posterior thoracolumbar spinal fusion surgery up to 4 segments.

ID: 1781

RF053: Identification of novel differentially methylated positions in adult spinal deformity patients that experienced perioperative complications

Quante Singleton ¹ , Rohit Bhan ¹ , Yu Zhang ¹ , Christopher Diaz ¹ , Christopher Ames ² , Bo Zhang ¹ , Michael Kelley ¹ , Nicholas Pallotta ¹ , Brian Neuman ¹

¹ Washington University in St. Louis, Orthopaedic Surgery, St. Louis, United States,

² University of California, Neurosurgery, San Francisco, United States

Introduction: The rising prevalence of adult spinal deformity (ASD) in an aging population, with surgical complication rates of 37%-71%, highlights the importance of pre-surgical risk assessment. Traditional risk factors like age and frailty partially account for perioperative complications, pointing to the need for patient-specific risk stratification. DNA methylation at certain CpG sites reflect aging and disease, which may predispose to perioperative complications. We aim to link genome-wide DNA methylation profiles from ASD patients to the risk of postoperative complications. Materials and Methods: ASD patients provided blood on the day of surgery. DNA methylation of peripheral blood mononuclear cells (PBMCs) was analyzed using IlluminaEPIC v2.0 BeadChip. Differential analysis between complication groups was performed in Minfi software. X and Y chromosomes were excluded to avoid sex bias. Differentially methylated positions (DMPs) were defined such that p<0.001 and absolute methylation difference between two groups was set to 0.05. Results: 30 surgical ASD patients were enrolled. 15 (50%) were revisions. 21 patients (70%) received all-posterior and 9 (30%) underwent anterior-posterior surgery. 7 (23%) received a three-column osteotomy and average levels fused was 11.9 (SD = 3.7). 47% (N = 14) experienced a post-operative complication, including pulmonary emboli (N = 2), death (N = 1), dehiscence (N = 1), altered mental status (N = 5), and acute kidney injury (N = 4). 50 significant DMPs were identified. 26 DMPs were hypomethylated and 24 were hypermethylated in the complication group. These sites had opposing methylation patterns in the non-complication group. Genes tagged were highly associated with immune response and lymphocyte function, such as LRBA (LPS-Responsive Beige-Like Anchor Protein) and NFACT2 (Nuclear Factor Activator of T-cells). DMPs tagged with regulators of the EGFR and WNT pathways (EPS8, APC2) were hypermethylated in the complication group. Conclusion: We identified 50 significant DMPs in patients that experienced complication after ASD surgery. These differences are linked to genes involved with lymphocyte and immune response, coinciding with increased epigenetic age. Further work could yield a differential methylation-based risk score specific to ASD. We aim to further evaluate these markers for enhancing pre-surgical risk assessment and precision-medicine.

ID: 159

RF054: The incidence and risk factors for bone cement displacement in patients with osteoporotic vertebral compression fractures after percutaneous kyphoplasty: a single-center retrospective study

Yonghao Wu ¹ , Shuaiqi Zhu ¹ , Yuqiao Li ¹ , Chenfei Zhang ¹ , Weiwei Xia ¹ , Zhenqi Zhu ¹ , Kaifeng Wang ¹

¹ Peking University People’s Hospital, Department of Spinal Surgery, Beijing, China

Introduction: Bone cement displacement (BCD) was one of serious complications following vertebroplasty in patients with osteoporotic vertebral compression fractures (OVCFs) and percutaneous kyphoplasty (PKP) might produce a promoting effect on the occurrence of it. However, there were few studies systematically exploring the risk factors of BCD after PKP. This research aimed to study the risk factors for BCD following PKP. Material and Methods: The clinical data of 463 patients who underwent single-entry PKP from June 2016 to August 2022 at our department were individually reviewed. Ultimately, a total of 181 patients (76.8% female, mean 73.67 ± 8.43 years old) were included with a median follow-up time of 7.00 months. Patients were categorized into the bone cement displacement group (n = 12) and the bone cement non-displacement group (n = 169). The diagnosis of BCD was that the lateral X-ray film showed that the bone cement was obviously displaced to the front of vertebral body or Computed Tomography (CT) revealed bone cement displacement > 2 mm. The following data were collected: age, gender, body mass index(BMI), underlying disease, history of fracture at other sites, injected bone cement volume, fractured vertebral segment, intravertebral vacuum cleft(IVC), postoperative distance between the bone cement and anterior edge of the vertebral body, sagittal position of the cement filling, contact between the bone cement and the endplate, distance between the bone cement and the vertebral endplates, collapse rate of the vertebral body, recovery rate of the vertebral anterior margin height, restoration rate of the Cobb angle, bone-cement distribution score, bone cement leakage and postoperative anti-osteoporosis treatment. Univariate analysis, binary logistic regression analysis and the AUC of ROC curve were conducted to identify possible risk factors, independent risk factors and discrimination ability, respectively. Results: The incidence of BCD following PKP in this study was 6.6% (12/181). The time from surgery to the occurrence of BCD ranged from 1 to 42 months, with a quartile of 7.00 (3.00, 15.00) months. Univariate Analysis showed that high BMI, preoperative IVC, high postoperative the vertebral anterior margin height, high recovery rate of the vertebral anterior margin height, high restoration rate of the Cobb angle, non-whole vertebral body of cement filling in sagittal position, noncontact between bone cement and endplates, high distance between the bone cement and the vertebral endplates, low postoperative bone-cement distribution score and bone cement leakage were possible risk factors for bone cement displacement following PKP (p < 0.05). The Binary Logistic Regression Analysis showed that independent risk factors associated with BCD after PKP were as follows: BMI (OR = 1.301,95%CI 1.002∼1.689), restoration of Cobb angle (OR = 1.036,95CI 1.007∼1.065), distance between bone cement and vertebral endplates (OR = 16.473, 95%CI 1.440∼188.395), and anterior bone cement leakage (OR = 29.200, 95%CI 3.552∼240.027). The ROC analysis results indicated that the AUC for BMI, the restoration of Cobb angle, bone cement leakage and the distance between bone cement and vertebral endplates were 0.687 (95%CI 0.510∼0.864), 0.759 (95%CI 0.591∼0.927), 0.689 (95%CI 0.540∼0.839) and 0.762 (95%CI 0.667∼0.858), respectively. Conclusion: Patients with a high BMI, a high restoration rate of the Cobb angle, a high distance between the bone cement and the vertebral endplates, and bone cement leakage have an increased risk of bone cement displacement after PKP.

RF04: ADULT SPINAL DEFORMITY 1

ID: 2182

RF055: Imaging features of post-traumatic thoracolumbar kyphosis: a retrospective analysis

Guangzhou Li ^1,2

¹ Suining Central Hospital, Spine Surgery, Suining, China,

² Affiliated Hospital of Southwest Medical University, Luzhou, China

Introduction: Understanding the imaging characteristics of post-traumatic thoracolumbar kyphosis (PTK) is conducive to accurate surgical plannings, however, few studies have focused on this aspect. The objective of this study was to investigate imaging characteristics of PTK. Material and Methods: Preoperative demographic, clinical, and radiographical parameters of 60 consecutive PTK patients (24 men, 36 women; average age: 56.6 ± 9.5 years) were evaluated. Patients were divided into spontaneous spinal arthrodesis (SSA: n = 37, 61.7%) and non-SSA groups by preoperative SSA status. The aforementioned parameters were compared between two groups and their correlation with SSA was determined by Spearman correlation test. Results: Injured vertebral bodies were primarily in T12 (n = 17, 28.3%), L1 (n = 29, 48.3%), and T11/L2 vertebral bodies (n = 7 each, 11.6%). Regarding AO classification, there were type A1 (n = 26), A3 or A4 (n = 30), and B (n = 4) fractures. Endplate damage accounted for 90% of the cases (upper: 31, lower: 9, both upper and lower: 14). Disease duration (SSA vs. non-SSA: 14.39 ± 12.43 years vs. 3.66 ± 5.55 years), local Cobb angle (36.5 ± 9.4° vs. 28.0 ± 6.4°), anteroposterior ratio (A/P, 0.40 ± 0.12 vs. 0.52 ± 0.10), anterior vertebral height ratio (AVH, 0.58 ± 0.14 vs. 0.44 ± 0.11), wedge angle (WA, 24.6 ± 9.2° vs. 17.6 ± 4.5°), and the presence of rigidity of kyphosis, were significantly different between two groups (all p < 0.05). SSA was significantly correlated with disease duration (r = 0.507), local Cobb angle (r = 0.551), WA (r = 0.408), rigidity of kyphosis (r = 0.509), A/P (r = -0.430), and AVH (r = 0.427) (all p < 0.05). Conclusion: PTK was mainly caused by compression and burst fractures with endplate injury and often accompanied by SSA. SSA was closely related to disease duration, local Cobb angle, WA, AVH, and the ratio of the injured anterior and posterior walls. Widespread SSA signs might contribute to rigid kyphosis.

ID: 1385

RF056: Impact of posterior column osteotomy on outcomes of single-level transforaminal lumbar interbody fusion: a retrospective analysis

Jialun Chi ¹ , Ved Vengsarkar ^1,2 , Kate Woods ³ , Hanzhi (Leo) Yang ¹ , Yi Zhang ⁴ , Jesse Wang ¹ , Lawal Labaran ¹ , Xudong Li ¹ , Jin Li ¹

¹ University of Virginia School of Medicine, Department of Orthopaedic Surgery, Charlottesville, United States,

² Rutgers New Jersey Medical School, Department of Orthopaedic Surgery, Newark, United States,

³ Creighton University School of Medicine, Department of Orthopaedic Surgery, Omaha, United States,

⁴ The Second Xiangya Hospital of Central South University, Department of Spine Surgery, Changsha, China

Introduction: The combination of Transforaminal Lumbar Interbody Fusion (TLIF) with PCO has been explored as a method to address spinal deformities. In patients at risk of developing kyphosis following a TLIF, a PCO can be an important adjunct procedure. However, the addition of a PCO is not without risks and may lead to instability due to the removal of posterior structures. Though the integration of these techniques has evolved as a solution to enhance patient outcomes in complex long-segment adult spinal deformity, there is a paucity of literature on its implications for short-segment fusion. This study aims to retrospectively analyze the outcomes of a single-level TLIF performed with and without PCO in order to better understand the impact of this combined approach on postoperative outcomes. Material and Methods: A retrospective review was performed using the PearlDiver national database. The study included all patients older than 18 years who underwent a single-level TLIF with and without PCO. A 1:5 ratio was used to match the 2 cohorts for age, sex, and relevant comorbidities. Multivariate logistic regression was used to compare 90-day and 2-year medical and surgical complications as well as 5-year reoperation rates. Results from the database were compared with a retrospective, single-center study. Segmental lordosis at either L4-L5 or L5-S1 was determined pre-operatively, post-operatively, and 2 years postoperatively using the Cobb technique. Multivariate logistic regression was used to determine postoperative complications and outcomes. Repeated measures ANOVA test with post-hoc analysis was used to identify significant changes in lordosis over time within each group. Independent samples t-test was used to identify significant changes in lordosis between groups post-operatively. Results: 2,637 patients in the national database who underwent TLIF and PCO were paired with 12,976 TLIF-only patients following the match. Patients undergoing TLIF with PCO exhibited increased 90-day postoperative rates of pneumonia (p = 0.001), pulmonary embolism (p = 0.014), sepsis (p = 0.004), and hyponatremia (p = 0.029), and a higher 2-year pseudarthrosis rate (p = 0.042). Over five years, the TLIF with PCO group also faced a significantly higher reoperation rate (p < 0.001). In the single-center study, patients undergoing a combined TLIF with PCO displayed greater estimated blood loss (EBL) (p < 0.001), operative times (p < 0.001), and post-operative hospital length of stay (p = 0.026). Patients who underwent TLIF with PCO had a significant increase in segmental lordosis immediately post-operatively (p < 0.001) and 2 years post-operatively when compared to pre-operative baseline (p < 0.001). Compared to the TLIF group, the TLIF+PCO group demonstrated a greater change in segmental lordosis between postoperative and preoperative imaging (-0.054 degrees vs. 4.61 degrees; p < 0.001) and between 2-years postoperative imaging and preoperative imaging (-0.89 degrees vs. 3.17 degrees; p < 0.001). Conclusion: The potential for over-correction with PCO in TLIF underscores the need for meticulous preoperative planning and patient selection. Spine surgeons should consider the extent of the spinal deformity and the correction required when choosing the appropriate surgical technique. In cases where significant sagittal correction is needed, alternative osteotomy techniques or additional procedures may be warranted to achieve the desired outcome.

ID: 1686

RF057: Evaluating Chat GPT responses to patient inquiries regarding adult spinal deformity surgery

Fergui Hernandez ¹ , Rafael Guizar ¹ , Jacob Ball ¹ , Marc Abdou ¹ , Henry Avetisian ¹ , William Karakash ¹ , Andy Ton ² , Emily Mills ¹ , Jeffrey C. Wang ¹ , Raymond Hah ¹ , Ram Alluri ¹

¹ Keck School of Medicine of USC, Department of Orthopaedic Surgery, Los Angeles, United States,

² University of California, Irvine, Department of Orthopaedic Surgery, Irvine, United States

Introduction: Adult spinal deformity (ASD) affects up to 68% of the elderly population. Surgical intervention for ASD, while potentially beneficial, is associated with complication rates of up to 50%. Research indicates there are often no significant improvements in patient-reported outcomes (PROs) following surgery. Given these challenges, comprehensive patient education regarding expected postoperative outcomes is crucial for managing patient expectations. However, the high patient volumes faced by spine surgeons often limit the time available for in-depth preoperative education. Language learning models (LLMs), such as ChatGPT, may function as a supplemental resource for additional patient queries. This study aims to evaluate ChatGPT-3.5's accuracy and comprehensiveness in answering frequently asked questions about ASD surgical correction. Materials/Methods: Structured interviews were conducted with patients who had previously undergone spinal deformity surgery at our institution. These interviews focused on their preoperative expectations and postoperative outcomes. Based on common themes from these interviews and frequently used online resources, we generated 40 questions. Three authors then selected 19 questions most relevant to patient inquiries, which were reviewed and approved by a board-certified orthopedic spine surgeon. Each question was posed to ChatGPT-3.5 in a separate “new chat” to ensure unique responses. Three spine surgeons evaluated the accuracy of ChatGPT-3.5's responses using a previously published scale. On this scale, a score of 1 indicates an excellent response without need for further clarification, while a score of 4 indicates an unsatisfactory response requiring substantial clarification. The readability of the responses was assessed using the Flesch-Kincaid Grade Level (FKGL) formula. The FKGL is a widely acknowledged and validated measure of readability in terms of academic grade levels. Results: The patient responses revealed four main themes: (A) preoperative preparation, (B) recovery (including pain expectations and physical therapy), (C) lifestyle modifications (such as restrictions and limitations), and (D) postoperative course. The accuracy of AI-generated responses varied across these themes. Preoperative preparation-related responses averaged an accuracy score of 1.67 out of 4. Both recovery and lifestyle modification questions received an average accuracy score of 1.33, while postoperative course questions averaged 2.0. AI-generated responses were graded as follows: 59.7 ± 15.2% excellent without need for further clarification, 26.3 ± 5.3% satisfactory with minimal clarification needed, 12.3 ± 16.9% satisfactory with moderate clarification needed, and 1.8 ± 3.0% unsatisfactory, requiring substantial clarification. Notably, the response to “Is there a chance my pain will return and get worse after undergoing spinal deformity surgery?” was the only one deemed inaccurate by all reviewers. Regarding readability, all 19 responses were found to be more complex than the average US adult reading level (eighth grade), exceeding it by an average of 5.91 grade levels. Conclusion: While ChatGPT shows potential as a patient education tool, the accuracy of its responses varies and often exceeds recommended readability levels. ChatGPT may serve as a useful adjunct in patient education by providing information that patients can discuss during their appointments. However, it should not be viewed as a replacement for direct patient-physician communication.

ID: 817

RF058: The characteristic of thoracolumbar vertebral fractures in patients with dropped head syndrome: an analysis of global spinal alignment in 90 cases

Soji Tani ¹ , Yoshifmi Kudo ¹ , Chikara Hayakawa ¹ , Ryo Yamamura ¹ , Ichiro Okano ¹

¹ Showa University, Tokyo, Japan

Objective: Dropped Head Syndrome (DHS) is a condition characterized by forward bending of the neck. We have previously reported the significance of thoracolumbar malalignment in patients with DHS and cervical spine malalignment. Many patients with global spinal malalignment also present with vertebral fractures, but detailed reports on the relationship between global spinal alignment abnormalities and vertebral fractures in DHS patients are lacking. This study aims to evaluate the characteristics of global spinal malalignment and thoracolumbar vertebral fractures in patients with DHS. Methods: This study included 90 patients with DHS who visited our hospital (mean age 75.8 ± 8.5 years; 76 females). The patients were divided into two groups: those with thoracolumbar malalignment (TL group) and those without (C group). Thoracolumbar malalignment was defined as any of the following: local kyphosis angle ≥ 30°, thoracic kyphosis (TK) ≥ 60°, or sagittal vertical axis (SVA) ≥ 50 mm. We compared global spinal alignment, the presence of vertebral fractures, and the location of fractures (upper thoracic spine, middle/lower thoracic spine, thoracolumbar junction, lumbar spine) between the two groups. Results: After excluding two patients due to inappropriate alignment measurement, data from 88 patients were analyzed. The TL group included 48 patients (54.5%, mean age 77.8 ± 7.1 years), while the C group included 40 patients (45.5%, mean age 73.4 ± 9.6 years). The TL group showed significantly higher values in SVA, T1 slope, TK, pelvic tilt (PT), and pelvic incidence-lumbar lordosis mismatch (PI-LL) and substantially lower LL compared to the C group (all, p < 0.01). The incidence of vertebral fractures was considerably higher in the TL group (n = 28, 58.3%) than in the C group (n = 6, 17.7%) (all, p < 0.001). Regarding fracture location, there was no significant difference between the groups in the upper thoracic spine, but the TL group showed significantly more fractures in the middle/lower thoracic spine (31.3% vs. 5.0%), thoracolumbar junction (41.7% vs. 10.0%), and lumbar spine (39.6% vs. 12.5%) (all, p < 0.01). Discussion: More than half of the DHS patients had thoracolumbar malalignment, and these patients had significantly more vertebral fractures, especially in the middle/lower thoracic spine and below. These findings suggest that vertebral fractures may influence the pathophysiology of DHS and that patients with such fractures are more likely to develop global spinal malalignment. Conclusion: In DHS patients with global spinal malalignment, it is crucial to consider the presence of vertebral fractures when evaluating their condition.

ID: 122

RF059: Risk factors for proximal junctional kyphosis in adult patients with congenital hemivertebra

Yilin Lu ^1,2,3 , Miao Yu ^1,2,3

¹ Department of Orthopaedics, Peking University Third Hospital, Beijing, China,

² Engineering Research Center of Bone and Joint Precision Medicine, Beijing, China,

³ Beijing Key Laboratory of Spinal Disease Research, Beijing, China

Introduction: Congenital hemivertebra (HV) is a morphological defect that occurs during embryonic development. Most patients with congenital hemivertebra are treated in childhood, but many do not receive surgical treatment until adulthood when the malformation has developed into a structural deformity. However, studies discussing the surgical treatment and prognosis for adult hemivertebra patients are rare. This study investigates the effectiveness of surgical treatment in adult patients with congenital hemivertebra and the risk factors for developing Proximal Junctional Kyphosis (PJK) after corrective surgery. Methods: This study retrospectively reviewed a cohort of congenital hemivertebra patients who underwent corrective surgery and had at least one year of follow-up. Inclusion criteria included being over 18 years old, having complete radiographic data, being diagnosed with congenital hemivertebra without other spinal diseases, and having no history of spinal surgery. Patients' baseline data, clinical features, surgical details, and radiographic parameters were retrospectively analyzed. Univariate and multivariate analyses were conducted to explore risk factors affecting the occurrence of PJK postoperatively. Results: The study included 70 patients, with 42 males (60%), and an average age of 35.51 years. The average follow-up duration was 22.5 months, and the average number of fused segments was 7.03. Postoperative spinal-pelvic parameters showed significant improvement compared to preoperative values. At the last follow-up, 20 patients (28.57%) had developed PJK. Univariate and binary logistic regression analyses indicated that the presence of multiple hemivertebrae and follow-up SVA were significantly associated with the occurrence of PJK (p = 0.016 and p = 0.010, respectively). Conclusion: Previous studies have shown that PI-LL and SVA are two key parameters in spinal deformities. Among the sagittal parameters, apart from SVA, there were no significant differences in PI-LL and other sagittal parameters between the groups. Additionally, based on the differences in baseline data and disease characteristics between the two groups, age, BMI, the presence of multiple hemivertebrae, and fusion to S1 were selected as potential risk factors. According to the results of this study, surgical treatment in adult patients with congenital hemivertebra generally achieves satisfactory outcomes, with multiple hemivertebrae and a larger follow-up SVA being risk factors for PJK.

Keywords: Proximal Junctional Kyphosis; Congenital Hemivertebra; Adult Spinal Deformity.

ID: 1660

RF060: Predictive factors of vertebral collapse for thoracolumbar osteoporotic vertebral compression fractures

Apratim Maity ¹ , Alexandra Echevarria ¹ , Claire Verret ¹ , Sarah Trent ¹ , Sohrab Virk ¹ , David Essig ¹

¹ Donald and Barbara Zucker School of Medicine at Hofstra/Northwell, Orthopedic Surgery, Hempstead, United States

Introduction: Although risk factors for osteoporotic vertebral compression fractures (OVCFs) have been widely studied, there exists no standard practice amongst spine surgeons for predicting when these fractures will lead to vertebral collapse. In 2010, the Spine Section of the German Society for Orthopedics and Trauma (DGOU) developed an Osteoporosis Fracture (OF) classification system to help identify anatomic abnormalities which can aid in the estimation of future vertebral collapse risk. Our study aimed to use the OF classification system to stratify a cohort of 1400 patients with OVCFs and identify radiographic markers that can be used to estimate the risk of further collapse. Methods: After receiving institutional review board approval #23-0902, patients seen in our institutions for the treatment of vertebral fractures were selected for review. 1400 patient charts were screened. Patients were excluded if they met any of the following criteria: age < 65, history of metastatic disease, multiple compression fractures, fractures caused by high impact injuries, fractures above T8, or history of prior thoracic/lumbar spine surgery. Included patients’ CT and MRI imaging were analyzed and OVCFs were classified according to the OF classification system. Additional radiographic parameters such as the presence or absence of vacuum phenomenon within the intervertebral disc space, vertebral level affected, vertebral height measurements, bony retropulsion, local kyphosis, lumbar lordosis, thoracic kyphosis, pelvic incidence, and paraspinal muscle Goutallier classification were recorded. Vertebral collapse was defined mathematically in two ways: vertebral compression ratio (VCR) % > 20 and anterior height compression (AHC) % > 20. Chi-squared analysis was performed to look for any statistical significance (p < 0.05) between indicated parameters and vertebral collapse. All statistics were conducted in R version 4.3.2. Results: Of the 1400 patients screened, 268 met inclusion criteria. Vertebral collapse rates for OVCFs classified as OF2 were ∼25%, for OF3 ∼50%, and OF4 ∼70% for both definitions of vertebral collapse (VCR%: p = 1.961e-09; AHC%: p = 3.531e-13). Furthermore, when defining collapse by VCR%, nearly 50% of OVCFs occurring at the thoracolumbar junction had collapsed compared to 20% for non-thoracolumbar junction OVCFs (p = 0.003). Lastly, when defining collapse using AHC%, OVCFs displaying observable intervertebral disc vacuum phenomenon on CT imaging showed a 50% collapse rate as opposed to a 33% collapse rate for those without the intervertebral disc vacuum phenomenon (p = 0.013). No significant relationships between adjacent level disc injury, muscle health, or lumbopelvic mismatch and vertebral collapse were found. Discussion: Identifying radiographic indicators that aid in predicting the progression of OVCFs can be immensely valuable in shaping the diagnostic and treatment strategies for one of the most frequently encountered orthopedic spinal conditions. Our results suggest that the OF classification system, as well as the thoracolumbar status and the presence of intervertebral disc vacuum phenomenon in relation to OVCFs may serve as indicators that an OVCF should be monitored more closely for risk of collapse.

ID: 535

RF061: Dental cement augmentation increases pullout strength with comparable removal torque for lateral mass screws

Javier Castro ¹ , James Mok ¹ , Karl Bruckman ¹ , Calvin Chan ¹ , Anna Karnowska ¹ , Harsh Wadhwa ¹ , Olivia Okoli ¹ , Jayme Koltsov ¹ , Serena Hu ¹

¹ Stanford University School of Medicine, Stanford, United States

Introduction: Premature loosening and fixation failure is a known problem of screw fixation of the spine, especially in cases of poor bone quality due to osteoporosis, tumor, or revision surgery. Cement augmentation of screws with PMMA, while described in the thoracolumbar spine, has limited utility in the cervical spine due to the small size of the bone and high risk of PMMA extravasation. Augmentation with dental cement may present a viable solution for posterior cervical spinal screw fixation. Material and Methods: 15 fresh frozen human cadaveric cervical vertebra were prepared by stripping all soft tissues. Lateral mass screw fixation (3.5x12 mm) was performed bilaterally with standard freehand technique by an attending spine surgeon. For augmented screws, dental composite (self-cure Stela composite, a BPA-free resin monomers with specially surface-modified nanoparticles of amorphous silica) was applied into the screw hole before placement of the screw. 9 vertebrae were used for pull-out testing. Screws were attached to a material testing machine (E10000) and axially loaded until failure. In the remaining 6 vertebrae, peak torque required to remove the screws from bone was measured via a digital torque driver. A t test was used to analyze the results between the augmented and non-augmented groups with significance set to p < 0.05. Results: Augmented lateral mass screws exhibited significantly higher pullout strength (263.8 ± 79.4N) compared to non-augmented screws (127.7 ± 21.2N). (p = 0.0005) There was no significant difference in the mean torque required for screw removal between the augmented (4.20 ± 2.83 lb-in) and non-augmented groups (4.49 ± 2.09 lb-in) (p = 0.9). The dental composite was radio-opaque and observable on xray. Conclusion: Augmentation with dental composite enhanced pullout strength without altering removal torque of cervical lateral mass screws in human bone. Further investigation of dental composited augmented screws is needed to identify additional applications for and long term performance of this technique. Dental cement augmentation of lateral mass screws during subaxial cervical spine fusion may be a safe and effective method of improving fixation strength without affecting ease of revision.

ID: 2791

RF062: Adeherence to the Lamartina-Berjano classification and suggested surgical treatment decreases the rate of postoperative mechanical failure in adult deformity patients. A retrospective observational study with a minimum 10 years follow-up

Domenico Compagnone ¹ , Luca La Verde ² , Andrea Redaelli ¹ , David Solano-Varela ³ , Francesco Langella ¹ , Marco Damilano ¹ , Daniele Vanni ¹ , Claudio Lamartina ¹ , Pedro Berjano ¹ , Riccardo Cecchinato ¹

¹ IRCCS Ospedale Galeazzi Sant'Ambrogio, Milan, Italy,

² University of Milan, Milan, Italy,

³ Universidad del Rosario, School of Medicine and Health Sciences, Bogotà, Colombia

Study Design: Retrospective cohort analysis. Objectives: To evaluate the effectiveness of the Lamartina-Berjano (L-B) classification in reducing mechanical complications in patients with adult spinal deformities, with a minimum follow-up of 10 years. Material and Methods: The study included cases of adult deformity with at least 10 years of follow-up. The rate of clinically-relevant mechanical complications, defined as any implant-related issue requiring revision surgery, was estimated. The independent variable was adherence to the treatment guidelines of the L-B classification. The analysis was limited to patients with thoracolumbar deformities, and the population was stratified according to postoperative alignment using GAP scores. Results: A total of 121 patients met the inclusion and exclusion criteria. In this cohort, the revision surgery rate for clinically-relevant mechanical complications was 49.6% (60 out of 121 patients). Of these, 90 patients (74%) had surgery following the L-B classification guidelines. A lower risk of complications was observed in aligned patients whose surgeries adhered to the L-B classification. Additionally, the survival curve showed significant differences between patients who followed L-B guidelines and those who did not. Conclusion: Our retrospective analysis shows that following the L-B classification guidelines leads to a reduction in mechanical complications in patients with thoracolumbar deformities, particularly in a long-term follow-up scenario.

ID: 1835

RF063: 4 rods fixation with bilateral iliac screws and sacral ala-iliac screws colud be a new fixation method to prevent rod breakage in circumferencial minimally invasive surgery for adult spinal deformity

Tomohisa Harada ^1,2 , Satoshi Makio ^1,2

¹ Sangubashi Spine Surgery Hospital, Tokyo, Japan,

² Rakuwakai Marutamachi Hospital, Kyoto, Japan

Introduction: Circumferential minimally invasive surgery (cMIS) using lateral interbody fusion (LIF) and percutaneous pedicle screw (PPS) for adult spinal deformity (ASD) is considered less invasive than conventional open surgery, but the high rod breakage rate is one of the problems. To prevent rod breakage, we have changed our fixation method from the initial 2-rods fixation to 3-rods and 4-rods fixation. The purpose of this study is to evaluate whether 4-rods fixation could be a new method to prevent rod breakage in cMIS for ASD. Material and Methods: The study included 78 ASD who had undergone correction from the lower thoracic to the pelvis using LIF and PPS. According to the number of rods used, the patients were divided into 3 groups: 2-rods group, 3-rods group, and 4-rods group. The number of fixation levels, operative time, intraoperative blood loss, radiological parameters (Cobb angle, Lumbar Lordosis (LL), Pelvic Tilt (PT), Pelvic Incidence (PI) -LL), and rod breakage rates at 1 and 2 years after surgery were examined. Results: There were 30 patients in the 2-rods group, 32 in the 3-rods group, and 16 in the 4-rods group. The mean fixation levels for each group were 8.0, 8.1, and 8.1, and the mean operative time and intraoperative blood loss were 415 minutes and 483 ml, 348 minutes and 370 ml, 321 minutes and 341 ml, respectively. The radiological parameters of each group were as follows: Cobb angle improved from 44° to 11°, 51° to 15°, 46° to 13°, LL from 4° to 48°, 13° to 51°, 12° to 50°, PT from 34° to 19°, 34° to 18°, 35° to 18°, PI-LL from 46° to 1°, 40° to 0°, 41° to -2. The rod breakage rates at 1 year after surgery were 3/30 (10%), 2/32 (6%), and 0/16 (0%), in each group and at 2 years after surgery were 7/30 (23%), 4/32 (13%), and 0/7 (0%), respectively. Discussions: There was no difference in the amount of intraoperative blood loss and corrective effect between the groups, but the operative time decreased over time, suggesting a learning curve effect. The rod breakage rate decreased as the number of rods used increased, and the rod breakage rate was 0% in the 4-rods group at both 1 and 2 years after surgery. This result was likely due to the use of both iliac screws and both SAI screws, which allow for completely independent 4-rods fixation. Another advantage of this method is that the four rods do not interfere with each other because of the different positions of the iliac and SAI screw heads. Conclusion: A new 4-rods fixation technique could be a new method to prevent rod breakage in cMIS for ASD.

ID: 1040

RF064: A prospective radiological and functional outcome study to compare the outcomes of mis-olif vs mis-tlif in management of degenerative scoliosis

Ayush Sharma ¹

¹ Dr. Babasaheb Ambedkar Memorial Hospital, Spine Surgery, Mumbai, India

Introduction: Minimally invasive Oblique lumbar interbody fusion (OLIF) and minimally invasive transforaminal interbody lumbar fusion (MIS-TLIF) are the two most popular minimally invasive fusion techniques for lumbar spine. The aim of the study was to compare the radiological and functional outcomes of OLIF vs MIS-TLIF in management of degenerative scoliosis. Results: 92 OLIF and 156 MIS-TLIF patients with more than one year follow up were included in final analysis. On comprising the VAS and ODI scores both OLIF and MIS-TLIF group shows significant improvement without any significant statistical difference at 3 months, 6 months and one year follow up. On comparing lumbar canal axial diameters on preoperative, six months follow up and one year follow up MRI, OLIF group showed significantly better improvement in canal decompression compared to MIS -TLIF. With mean increase in canal diameter of 72% at one year follow up for OLIF group. While comparing the correction in coronal and sagittal imbalance OLIF groups showed significant better correction in scoliosis and PI-LL (Pelvic incidence and lumbar lordosis) mismatch .The mean correction in scoliosis was 12 degrees in OLIF group com compared to 4 degrees in MIS -TLIF (p = 0.01) similarly the mean correction in PI-LL mismatch was 10.09 degrees for OLIF patients compared to 6.8 for MIS-TLIF (p = 0.03).Return to work after surgery in days was significant faster for OLIF group with p = 0.002 . Conclusion: Both OLIF and MIS -TLIF can result in significant improvement in VAS and ODI scores after lumbar interbody fusion for degenerative scoliosis. OLIF surgery results in better decompression and better correction of sagittal /coronal imbalance with faster return to work compared to MIS -TLIF.

ID: 1584

RF065: Exploring the role of acetabular version and pelvic parameters on compensatory mechanisms for sagittal imbalance: insights for spine and hip surgeons

Ethan Sheppard ¹ , Zuhair Mohammed ¹ , Gerald McGwin ² , Steve Theiss ¹

¹ University of Alabama at Birmingham Heersink School of Medicine, Orthopaedic Surgery, Birmingham, United States,

² University of Alabama at Birmingham Heersink School of Medicine, Epidemiology, Birmingham, United States

Introduction: Positive sagittal spine imbalance, characterized by an abnormal forward alignment of the spine, often causes back pain and disability, particularly in older adults. The body compensates for this imbalance by increasing pelvic tilt through hip hyperextension. While some patients can significantly increase pelvic tilt to improve sagittal alignment, others cannot. The role of acetabular version - the orientation of the hip socket - in these compensatory mechanisms is unclear, as acetabular version affects hip hyperextension. Understanding whether hip anatomy limits the ability to increase pelvic tilt could clarify how patient-specific factors influence the body’s capacity to manage sagittal imbalance. Objectives: This study aimed to assess whether acetabular anatomy or version influences a patient's ability to compensate for sagittal imbalance by increasing pelvic tilt. Material and Methods: A retrospective review was conducted on 101 patients with adult spinal deformity treated at the University of Alabama at Birmingham from 2013 to 2022. Eligible patients were over 18, with no history of thoracolumbar fusion or hip surgery. Standing scoliosis films and CT images of the lumbar spine or pelvis were analyzed. Spinopelvic parameters, including pelvic incidence (PI), pelvic tilt (PT), lumbar lordosis (LL), and sagittal vertebral axis (SVA), were assessed on lateral standing full-spine radiographs, while acetabular version and center edge angle (CEA) were measured on CT scans. Patients were grouped into three cohorts based on sagittal balance and the ability to compensate with increased pelvic tilt: sagittally imbalanced with normal PT (Group 1), sagittally balanced with abnormal PT (Group 2), and sagittally imbalanced with abnormal PT (Group 3). Kruskal-Wallis tests were used for statistical analysis. Results: All groups were demographically similar. There were no statistically significant differences in acetabular version or CEA among the three cohorts (p > 0.05), although the acetabular version of groups able to increase pelvic tilt trended toward significance. Groups 1 and 3 had significantly higher PI-LL mismatch than Group 2. PI was significantly greater in Groups 2 and 3, who were able to increase pelvic tilt to compensate for sagittal imbalance. Discussion: The study suggests that acetabular version or coverage (CEA) does not significantly affect a patient's ability to compensate for sagittal imbalance by increasing PT through hip hyperextension. Instead, PI may be a governing factor in the ability to increase pelvic tilt. Group 1, with the lowest median PI, showed less ability to increase PT for compensation, whereas higher PI values in the other groups correlated with increased PT. Conclusion: Acetabular version does not significantly influence compensation for sagittal imbalance, while PI may better predict a patient’s ability to compensate via increased PT. Although acetabular version might not directly affect sagittal balance, its role in spinopelvic dynamics warrants further investigation. Future research with larger cohorts, dynamic imaging, and advanced 3D modeling is necessary to clarify the interplay between pelvic and acetabular parameters, potentially refining surgical strategies and improving patient outcomes.

ID: 2594

RF066: More rods, better outcomes? Impact of multi-rod constructs on rod fracture rates in adul spinal deformity surgery

Diego Soto Rubio ¹ , Bryan Clampitt ² , Molly Monsour ² , Samantha Schimmel ² , Kiana Yeganeh ³ , Jay I. Kumar ¹ , Cesar Carballo ¹ , Puya Alikhani ¹

¹ Department of Neurosurgery and Brain Repair, University of South Florida, Morsani College of Medicine, Tampa, Florida, USA., Tampa, United States,

² USF Health Morsani College of Medicine, Tampa, Florida, USA., Tampa, United States,

³ Ponce Health Sciences University School of Medicine, Ponce, Puerto Rico, USA, Ponce, United States

Introduction: Achieving successful correction in adult spinal deformity (ASD) surgeries is challenging, with significant stress placed on both vertebral alignment and surgical hardware. Rod fracture remains a frequent complication, prompting exploration into multi-rod constructs aimed at reducing hardware fatigue and improving clinical outcomes. Such constructs are hypothesized to distribute stress more evenly along the spinal column, potentially decreasing the incidence of rod fractures postoperatively. Material and Methods: A retrospective review encompassed 264 ASD surgeries conducted at our tertiary care center from 2016 to 2023. Inclusion criteria required patients with a follow-up exceeding one year, focusing on those with constructs spanning from the pelvis to an upper instrumented vertebra (UIV) at T12 or higher. Data included number of rods, fused levels, rod fractures, and patient demographics. Patients were categorized into two groups: those with traditional 2-rod constructs and those with 3 or more rods. Statistical analysis utilized SPSS software. Results: Among the 148 cases analyzed, 74.5% utilized a 2-rod construct, while 13.7%, 7.8%, and 0.4% employed 3, 4, and 5 rods, respectively. The average number of instrumented levels was 10.06 (± 2.64), with no significant difference observed between patients with and without rod fractures (p = 0.583). Rod fracture rates were significantly lower in constructs with 3 or more rods compared to traditional 2-rod constructs (23.2% vs. 42.4%, p = 0.018). Of the 51 rod fractures identified, 96.1% necessitated revision surgery, with additional rods incorporated in 12.2% of these cases. Two patients did not undergo revision due to either evidence of fusion or medical comorbidities precluding surgery. Conclusion: Multi-rod constructs demonstrate a notable association with reduced rod fracture rates in ASD patients undergoing pelvic instrumentation. Integrating supplementary rods in extended spinal fusions emerges as a critical factor in surgical planning to mitigate the risk of postoperative rod fractures and improve overall surgical outcomes. This approach underscores the importance of optimizing hardware configurations to enhance the durability and efficacy of spinal deformity corrections.

ID: 1774

RF067: Surgery improves sexual life as well as physical activity in adult spinal deformity patients: predictive factors

David Van Schaik ¹ , Alice Baroncini ² , Lisa Goudman ^3,4 , Daniel Larrieu ² , Javies Pizones ⁵ , Anouar Bourghli ⁶ , Louis Boissiere ² , Ibrahim Obeid ²

¹ Free University of Brussels, Orthopaedics and Traumatology, Brussels, Belgium,

² Hopital de Bordeaux, Orthopaedics and traumatology, Bordeaux, France,

³ Free University of Brussels, STIMULUS research group, Brussels, Belgium,

⁴ Research Foundation - Flanders (FWO), Brussels, Belgium,

⁵ European Spine Study Group Essg, Barcelone, Spain,

⁶ Kingdom Hospital, Neurosurgery, Riyadh, Saudi Arabia

Introduction: A spinal disease can have a severe impact on the patient’s sex life, resulting in decreased sexual function, libido, and sexual satisfaction. Eventually, this can lead to a lower (sexual) quality of life and cause depression and relationship distress. Spinal surgery is suggested to improve sexual function; however, in-depth evaluations concerning sexual health after spinal surgery and predictors of improvement are still scarce. Therefore, this study evaluated which factors predicted improvement in sexual health in patients with adult spinal deformity (ASD) who underwent surgical treatment. Material and Methods: A retrospective review of a prospective multicenter database was collected from 5 centers with a minimum follow-up (FU) of 2 years. Inclusion criteria were age > 18 years and a diagnosis of ASD, as defined by one of the following parameters: Cobb angle > 20°, pelvic tilt (PT) ≥ 25°, sagittal vertical axis (SVA) ≥ 5 cm, or thoracic kyphosis ≥ 60°. The association between COMI-back items, SRS-22 items, SF-36 items, and ODI question 8 (Q8) was explored with Pearson correlations and Principal Component Analysis (PCA). Improvement in sexual health was evaluated through a 1-point decrease on question 8 of the ODI. Comparisons between patients with and without improvement in sexual health, and the non-response to question 8 of the ODI in pre-op, were evaluated with two-sample t-tests. IBM SPSS (version 26.0) and R Software Version 4.1.2 (R Foundation for Statistical Computing, Vienna, Austria) were used for the statistical analysis. Results: Data from 880 patients were collected at baseline and at 2 years. The total number of patients with an answer to Q8 after 2 years was 365 (41%). PCA with rotation indicated that sexual health was related to the level of activity of the patients and was dependently correlated with questions 5 and 18 of the SRS-22 and 3d to 3j of the SF-36. The main factors associated with non-response to ODI question 8 were older age, worse sagittal imbalance, and nationality. Patients with an improvement in sexual health at 2 years of FU were those with a worse quality of life in pre-op, older patients with greater sagittal correction, and a better improvement in physical activity levels after surgery (p < 0.000). Improvement was also associated with pelvic fixation and 3-column osteotomies. No significant difference in terms of general PROMs at 2 years FU was found between the two groups. Conclusion: Non-response to ODI Q8 on sexual activity was correlated with age and nationality. ASD surgery could improve sexual health scores, which were correlated with improved physical activity, severely deformed patients with worse preoperative quality of life scores, and better postoperative sagittal correction.

ID: 877

RF068: Application of non-radiation scoliosis screening technology based on artificial intelligence and pressure sensing monitoring

Fang Xie ¹ , Zhuojing Luo ¹ , Xueyu Hu ¹

¹ Xijing Hospital, Xi’an, China

Introduction: To explore the feasibility of using high-precision pressure real-time sensing detection technology to achieve radiation free screening of scoliosis. Material and Methods: Clinically diagnosed patients with scoliosis and volunteers without scoliosis were recruited. We use a flexible pressure sensing detection device to obtain the abnormal characteristics of body pressure distribution caused by scoliosis in patients. We also utilize convolutional neural network artificial intelligence algorithm to obtain the accuracy and area under the curve (AUC) of determining whether scoliosis exists, the number of bends (single curve, double curves, and triple curves), and the curvature type (upper thoracic curve, thoracic curve, thoracolumbar curve, and lumbar curve). Results: 230 patients with scoliosis and 100 volunteers without scoliosis were included in the study. Trunk pressure distribution data were obtained using pressure monitoring clothing. Using the artificial intelligence algorithm, the accuracy of determining the presence or absence of scoliosis was 83%, with an AUC of 0.887; the accuracy of determining the number of bends was 72.5%, with an AUC of 0.925; and the accuracy of determining the curvature was 64.1%, with an AUC of 0.858. Conclusion: Due to skeletal asymmetry, patients with scoliosis experience significantly abnormal body pressure compared to the normal population. Flexible stress testing can be used as a non-radiative clinical tool for screening and evaluating scoliosis, and larger sample sizes are needed in the future to improve screening accuracy and reliability.

ID: 2847

RF069: Can we rely on reciprocal change to occur in the unfused thoracic spine in adult spinal deformity patients undergoing lower thoracic to pelvis fusions?

François Dantas ¹ , Fatemeh Alavi ² , Christopher J. Nielsen ³ , Stephen Lewis ³ , Raja Rampersaud ³

¹ Toronto Western Hospital, Neurosurgery, Toronto, Canada,

² Osteoporosis Program, Schroeder's Arthritis Institute, University Health Network, Toronto, Canada,

³ Toronto Western Hospital, Orthopedic Surgery, Toronto, Canada

Introduction: Deformity correction for degenerative scoliosis is common with long fusions from the low thoracic spine to the pelvis frequently being performed. Despite accurate restoration of sagittal alignment in adult spinal deformity surgery (ASD), unknown reciprocal change (RC) in the non-instrumented spine can lead to unsatisfactory sagittal balance. Determining the ideal upper instrumented vertebra in these constructs relies on predicting the expected reciprocal changes that will occur in the unfused thoracic spine proximal to the fusion. The aim of this study was to determine the incidence of reciprocal changes following fusions from the distal thoracic spine to the pelvis and its association with proximal junctional kyphosis (PJK). Material and Methods: Ninety-one consecutive patients (mean age 66.7 ± 10.8 years, 65.9% females) who underwent fusion from the lower thoracic spine to the pelvis in a single institution were retrospectively reviewed. Upper-instrumented vertebra (UIV) was T9-T12 in all cases and all patients had a minimum follow-up of one year. The measurements on preoperative and immediate postoperative spinopelvic parameters were performed. The patients were stratified based on their preoperative T1 to UIV kyphosis (T1_UIV) into three categories: Hypokyphosis (< 30°), Normokyphosis (between 30° and 40°), Hyperkyphosis (> 40^o). The patients were classified based on their post-to-preoperative changes in T1_UIV_Cobb angle into no reciprocal change (NRC) (< 5^o), minimal reciprocal change (MRC) (between 5^o and 10^o), and reciprocal change (RC) (> 10^o). Statistical tests were used to determine the association between thoracic kyphosis, reciprocal changes, and PJK development. The rate of PJK was compared between the groups. Results: No reciprocal change was present in 36.2%, minimal reciprocal change in 42.8%, and reciprocal change (dT1_UIV_Cobb > 10^o) was observed in 20.8% of patients. There was no significant association between the preoperative amount of thoracic kyphosis and upper thoracic reciprocal change (p = 0.184). The development of PJK was not associated with preoperative thoracic kyphosis (p = 0.570) or reciprocal changes (p = 0.116). The overall incidence of PJK was 46% (42/91). The lowest PJK rate was in the group of patients with reciprocal change (26%). Conclusion: The overall incidence of upper thoracic reciprocal change following lower thoracic to pelvis fusions in ASD patients was only 20.8%. In this cohort of 91 patients, there was no association between the development of PJK and reciprocal changes. We observed the lowest rate of PJK in patients who demonstrated reciprocal change. When considering spinal fusions for adult spinal deformity from the lower thoracic spine to the pelvis, surgeons should not expect any significant compensation or reciprocal change to occur in the sagittal alignment from the non-fused thoracic spine.

ID: 2793

RF070: Intraoperative neuromonitoring alerts, responses, and postoperative neurological outcomes in lumbar high-grade lumbar spondylolisthesis fusion surgery: AO Spine international multicenter spinal deformity intraoperative monitoring (SDIM) study

Thorsten Jentzsch ¹ , Anna Rienmüller ² , Colby Oitment ³ , Yong Qiu ⁴ , Ferran Pellise ⁵ , Ahmet Alanay ⁶ , Justin Smith ⁷ , Nasir Quraishi ⁸ , Randolph Gray ⁹ , Saumyajit Basu ¹⁰ , Go Yoshida ¹¹ , Amer Aziz ¹² , Lawrence Lenke ¹³ , Stephen Lewis ¹⁴ , AO Deformity Knowledge Forum

¹ Balgrist University Hospital, Orthopedics, University of Zurich, Zurich, Switzerland,

² Medical University of Vienna, Orthopedics, Vienna, Austria,

³ Scarborough Health Network, Orthopedics, Toronto, Canada,

⁴ Drum Tower Hospital of Nanjing University Medical School, Nanjing, China,

⁵ Hospital Universitari de la Vall d’Hebron, Barcelona, Spain,

⁶ Acibadem Mehmet Ali Aydinlar University School of Medicine, Istanbul, Türkyie,

⁷ University of Virginia, Virginia, United States,

⁸ Nottingham University Hospitals NHS Trust, Nottingham, United Kingdom,

⁹ The Children`s Hospital Westmead, St. Leonards, Australia,

¹⁰ Kothari Medical Centre, Kolkata, India,

¹¹ Hamamatsu University School of Medicine, Hamamatsu, Japan,

¹² Ghurki Trust Teaching Hospital, Lahore, Pakistan,

¹³ Columbia University Medical Center, New York, United States,

¹⁴ Toronto Western Hospital, Orthopedics, University of Toronto, Toronto, Canada

Introduction: This study aimed to record intraoperative neuromonitoring changes and postoperative outcomes in patients with high-grade spondylolistheses. Material and Methods: This study was part of the AO Spine international multicentric spinal deformity intraoperative monitoring (SDIM) study (n = 555). It consists of a subgroup of nine patients with high-grade spondylolisthesis, who underwent dorsal fusion surgery. Intraoperative monitoring recorded alerts through assessment of motor evoked potential (MEP), somatosensory evoked potential (SSEP), and electromyography monitoring (EMG). Postoperative evaluation consisted of American Spinal Injury Association (ASIA) Lower Extremity Motor Score (LEMS). Results: GENERAL: Five (55.6%) patients showed alerts, while four (44.4%) patients did not show alerts. Of those with an alert, three (60.0%) patients had one alert, one (20.0%) patient had two alerts, and one (20.0%) patient had five alerts. Patients with alerts tended to be older than those without alerts (median [interquartile range (IQR)] 36.0 [26.0] versus 28.5 [27.0] years). Five (71.4%) females had an alert, while no (0%) male had an alert. RADIOLOGICAL ALIGNMENT: Patients with alerts had higher sagittal C7 plumb lines (median (IQR) 44.9 (21.1) versus 30.0 (48.5) millimeters. SURGICAL TECHNIQUE: All (n = 3 [100%]) revision surgeries had an alert, while 2 (33.3%) primary surgeries showed an alert. All osteotomies (n = 3 [100%]) had an alert while 2 (33.3%) patients without osteotomy had an alert. Of patients with an osteotomy, two (66.7%) patients had a (Schwab) type 3-4 osteotomy, while one (33.3%) patient had a type 2 osteotomy. TYPE OF ALERTS: In all (100%) patients with alerts, MEP changes were observed. Of these, 3 (50.0%) were MEP alerts only. One alert (16.7%) presented with unilateral MEP and SSEP changes. Two alerts were unilateral MEP and EMG changes. TIME OF MEP ALERTS: The median time to an MEP alert was 171.5 (IQR 88) minutes. One unilateral MEP alert was due to an osteotomy type 3-4, two (one unilateral and one bilateral) due to correction, one unilateral due to traction, and another two due to other reasons. RESPONSES TO ALERTS: In response to MEP alerts, blood pressure was elevated once, blood transfusion was done once, rod removal was performed twice, implant removal was done once , the osteotomy was opened once, steroids were given once, and decompression was performed once, while other measures were done in response to three alerts. Most alerts recovered (n = 4 [66.7%] versus n = 2 [33.3%]). Most patients with unilateral alerts recovered, while only half of bilateral alerts recovered (n = 4 [80%]) versus n = 1 [50%]). The median time to recovery was 3.5-4.0 (IQR 0.0-1.0) minutes. POSTOPERATIVE OUTCOME: Two (22.2%) patients presented with de novo postoperative neurological deficits with decrease of ASIA LEMS. Of these, all (100%) showed intraoperative alerts. Yet, of those 5 patients with intraoperative alerts, only 2 (40.0%) showed postoperative neurological deficits. Conclusion: In posterior fusion of high-grade spondylolistheses, intraoperative neuromonitoring alerts (55.6%) and postoperative deficits (22.2%) are common. Intraoperative measures to alerts are important to decrease postoperative deficits.

ID: 2817

RF071: Risk factors for IONM alerts

Anna C. Rienmüller ¹ , Kenny Yat Hong Kwan ² , Yong Qiu ³ , Ferran Pellise ⁴ , Ahmet Alanay ⁵ , Justin Smith ⁶ , Nasir Quraishi ⁷ , Randolph Gray ⁸ , Saumyajit Basu ⁹ , Go Yoshida ¹⁰ , Amer Aziz ¹¹ , Lawrence Lenke ¹² , Stephen Lewis ¹³

¹ Medical University Vienna, Vienna, Austria,

² University of Hong Kong, Hong Kong, Hong Kong,

³ Nanjing University Medical School, Nanjing, China,

⁴ Hospital Universitari de la Vall d’Hebron, Barcelona, Spain,

⁵ Acibadem Mehmet Ali Aydinlar University School of Medicine, Istambul, Türkyie,

⁶ University of Virginia, Charlottesville, United States,

⁷ Nottingham University Hospitals NHS Trust, Nottingham, United Kingdom,

⁸ The Children`s Hospital Westmead, St. Leonards, Australia,

⁹ Kothari Medical Centre, Kolkata, India,

¹⁰ Hamamatsu University School of Medicine, Hamamatsu, Japan,

¹¹ Ghurki Trust Teaching Hospital, Lahore, Pakistan,

¹² New York Presbyterian, Columbia University Medical Center, New York, United States,

¹³ University Health Network, Toronto Western Hospital, Toronto, Canada

Introduction: Adult spinal deformity (ASD) surgery presents significant challenges due to its complexity and the potential for neurological complications. Intraoperative neuromonitoring (IONM) is a standard of care that provides real-time feedback on the integrity of neural structures to prevent neurological injury. However, IONM alerts during surgery indicate potential intraoperative risks, requiring prompt intervention to mitigate damage. Identifying the risk factors associated with these alerts is crucial for optimizing surgical outcomes and minimizing postoperative complications. Material and Methods: A large multicenter study including patients aged between 10 and 80 years undergoing spinal complex deformity surgery was conducted to assess IONM alerts. An IONM alert was defined as somatosensory evoked potential (SSEP) and/or Motor evoked potential (MEP) amplitude loss > 50% in two of three muscle groups and/or Electromyogram (EMG) sustained activity for > 10 seconds. Univariate tests were performed to explore patient-specific and surgical risk factors for having an IONM alert. Subgroups regarding SSEP and uni- or bilateral MEP changes were assessed. Results: 555 patients (349 cord-level surgeries, 197 non-cord-level surgeries, and nine spondylolisthesis) were included in this study. IONM alerts occurred in 84 patients (15.1%). 57 patients in cord-level surgery (16.3%), 22 patients in non-cord-level surgery (11.2%) and five patients with spondylolisthesis surgery (55.6%). Significant risk factors for having an IONM alert included the primary diagnosis (spondylolisthesis), revision surgery, gender (female), higher maximum Coronal Cobb angle and Coronal deformity angular ratio (DAR), and intraoperative traction, higher BMI. Significant risk factors for MEP alerts were similar, whereas risk factors for SSEP alerts were only female gender and body mass index. The most common surgical event leading to an alert was correction/rod placement with 64%, and non-surgical event was anesthesia-related with 60%. Conclusion: Various risk factors were identified for IONM alerts during adult deformity surgery. Large coronal deformities, especially with high DAR and patients undergoing surgery for high grade spondylolisthesis were at particular high risk of IONM alerts. Rod placement/correction was the stage of surgery most likely associated with IONM alerts, highlighting the need for extra vigilance during this part of the procedure.

ID: 394

RF072: Novel radiological predictors for the progression of proximal junctional kyphosis in osteoporotic vertebral compression fracture with kyphosis following posterior corrective surgery

Junyu Li ¹ , Yinghong Ma ¹ , Baitao Liu ¹ , Junjie Ma ¹ , Zhuo Ran Sun ¹ , Yongqiang Wang ¹ , Miao Yu ¹ , Weishi Li ¹ , Yan Zeng ¹

¹ Peking University Third Hospital of China, Beijing, China

Introduction: With population aging, the Osteoporotic Vertebral Compression Fracture (OVCF) has become an important public problem. Previously, we used sagittal parameters such as TK, SVA, PI-LL to make surgical plans, but for OVCF patients with thoracolumbar deformity, it is more suitable to focus on the thoracolumbar parameters to provide reference for orthopedic strategies. This study aimed to identify the effect of some novel risk factors associated with L1 vertebrae and parameters closely related to the thoracolumbar segment for the occurrence of proximal junctional kyphosis (PJK) following surgery for patients with osteoporotic vertebral compression fractures. Material and Methods: A total of 74 OVCF patients undergoing posterior corrective surgery between January 2008 and June 2021 with a minimum 2-year follow-up were included. These patients were divided into PJK and non-PJK groups. Spinopelvic parameters, thoracolumbar slope (TLS), and the L1 plumb line (L1PL) were measured preoperatively, postoperatively, and at follow-up. Multivariate logistic analysis was performed on various risk factors as well as Global Alignment and Proportion (GAP) score. Associations between novel parameters and PJK were analyzed using receiver operating characteristic analysis. Results: PJK was identified radiographically in 28.4% of patients. The mean age and follow-up were 63.45 years and 38.17 months, respectively. There was no difference between the PJK and the non-PJK groups in baseline demographics, pre-operative and immediate post-operative pelvic incidence-lumbar lordosis mismatch. Multiple comparisons showed that the proportion of PJK in the severely disproportioned group (the group of the highest GAP scores) and that of other two groups of lower GAP scores was statistically different (p < 0.001). Potential risk factors for PJK included preoperative TK (p < 0.001), TLS (p = 0.016), and postoperative TLS (p < 0.001), L1PL (p < 0.001). Postoperative TLS and L1PL were respectively independent as risk factors for PJK, with the cut-off values set at 8.6° and 10.4 mm to predict the occurrence of PJK. Conclusion: TLS and L1PL can be used to predict the occurrence of PJK in patients undergoing surgery for OVCF and are crucial for preventing the progression of PJK. Achieving a proportionate GAP Score postoperatively seems to be a viable option as higher GAP scores were associated with higher rates of PJK.

RF05: DEGENERATIVE SPINE

ID: 2808

RF073: Impact of degenerative cervical radiculopathy - Assosiated headache (DCR-HA) on surgical outcome

Samer Habiba ^1,2 , Elisabet Danielsen ³ , Tor Ingebrigtsen ^2,4 , Tore Soldberg ^2,4

¹ 1Department of Neurosurgery, University Hospital of North Norway, Tromsø, Norway,

² Institute of clincial medicine,UiT The Arctic University of Norway, Tromsø, Norway, Tromsø, Norway,

³ 2Faculty of Health Sciences, UiT The Arctic University of Norway, Tromsø, Norway,

⁴ 3Department of Neurosurgery and the Norwegian Registry for Spine Surgery (NORspine), University Hospital of North Norway, Tromsø, Norway

Introduction: Degenerative cervical radiculopathy (DCR) associated arm pain is the most frequent cause for cervical spine surgery. Yet, neck pain (NP) and concurrent headaches (HA) are common among these patients. Prior studies have identified various prognostic factors that predict a successful outcome, but it is unknown whether headache is associated with surgical outcomes. This study aims to determine whether DCR-HA is an independent prognostic factor for surgical success. Material and Methods: In this study o6,234 patients were operated for anterior cervical surgery for DCR, consecutively registered in the Norwegian Registry for Spine Surgery (NORspine) and followed for one year. Binary logistic regression was used to evaluate if DCR-HA was associated to successful outcomes, defined as a ≥ 35% improvement in the Neck Disability Index (NDI), when adjusted for potential confounders. The secondary outcome measures were the numeric rating scales (NRS) for headache (NRS-HA), neck pain (NRS-NP) and arm pain (NRS-NP), and health related quality of life with EuroQol five dimensions five-level (EQ-5D). Results: In our cohort, 4566 (73.2%) reported DCR associated headache. Patients with headaches had higher baseline levels of NRS-HA, NRS-NP and NRS-AP and EQ-5D, of which had significant improvement at 12 months follow-up. The presence of headache was associated with a 37% (odds ratio: 0.63, 95% confidence interval 0.51 - 0.70; p < 0.001) lower likelihood of achieving a successful outcome. In subgroup analyses, each unit increase in NRS-HA scale was associated with an 8% decrease in the likelihood of successful outcomes (p < 0.001). Conclusion: DCR-HA is an independent prognostic factor for surgical non-success in patients operated for DCR. These findings underscore the importance of incorporating DCR-HA into pre-surgical evaluations and discussions, potentially guiding the development of clinical guidelines to optimize patient treatment and outcomes.

ID: 2270

RF074: Hounsfield units as a predictor of cage subsidence and clinical outcomes following anterior cervical discectomy and fusion

Jason Salvato ¹ , Taylor Moglia ¹ , Ara Khoylyan ¹ , Frank Vazquez ¹ , Arpitha Pamula ¹ , Alex Tang ² , Tan Chen ³

¹ Geisinger Commonwealth School of Medicine, Scranton, United States,

² Geisinger Health, Orthopaedic Surgery Northeast Residency, Wilkes-Barre, United States,

³ Geisinger Health, Department of Orthopaedic Surgery, Wilkes-Barre, United States

Introduction: Anterior cervical discectomy and fusion (ACDF) is a common procedure for addressing refractory cervical degenerative disease. A notable post-operative complication is intervertebral cage subsidence, which can lead to spinal deformity, recurrence of neurological symptoms, hardware failure, and poor fusion outcomes. Literature has shown a correlation between bone mineral density (BMD) and risk of subsidence. Hounsfield Units (HU) derived from computed tomography (CT) scans have been proposed as a surrogate for assessing BMD outside dual-energy X-Ray absorptiometry. The purpose of this study was to (1) determine if cervical HU values are associated with radiographic subsidence following ACDF, (2) evaluate which cervical levels are most predictive, and (3) identify any relationship between subsidence, HU, and long-term clinical outcomes. Material and Methods: A retrospective chart review was performed identifying patients with degenerative spine pathology who’ve had recent preoperative CT imaging, undergoing elective single-level ACDF between 2019 and 2023. Patients with non-degenerative diagnoses, revision surgeries of the index level, multilevel ACDF procedures, and corpectomies were excluded. Patient demographics, longitudinal clinical outcomes scores, and HU of C2-C7 vertebrae were recorded. HU measurements were performed at each vertebral body (C2-C7; mid-sagittal). Based on prior literature, moderate radiographic subsidence was defined as collapse of the interbody cage by greater than one-third but less than two-third of cage height. Collapse greater than two-third of total cage height was defined as severe subsidence. Descriptive and inferential statistics were performed. Results: A total of 39 patients (33 no subsidence, 6 subsidence) met inclusion criteria. There were no differences in cohort age (52.8yo vs 52.5yo, p = 0.966), BMI (32.1 vs 33.2, p = 0.370), gender (46% vs 33% male, p = 0.582), or use of plating (58% vs 50%, p = 0.731). No significant differences were noted in HU values between the subsidence and non-subsidence cohorts across all cervical levels, with mean HU values of 368.5 ± 20.85 for the subsidence cohort and 385.17 ± 27.31 for non-subsidence cohort. Both cohorts demonstrated similar long term clinical improvement in terms of ΔNDI (-19.1 vs -20.4, p = 0.800), ΔPROMIS-Overall (2.3 vs 6.1, p = 0.375), ΔPROMIS-Physical (4.1 vs 7.5, p = 0.623), and ΔPROMIS-Mental (0.9 vs 5.3, p = 0.502). Multivariate analysis demonstrated HU values were not significant predictors of cage subsidence at any cervical level (p > 0.05). HU values at C5 (r = 0.477, p = 0.043), C6 (r = 0.602, p = 0.011), and C7 (r = 0.490, p = 0.046) were positively correlated with long term NDI scores. Conclusion: Preoperative Hounsfield units (HU) of the cervical spine were not correlated with radiographic cage subsidence following single level ACDF for degenerative pathology after controlling for patient demographics and use of anterior plating. While Hounsfield units have been found to be correlated with bone density and cage subsidence in lumbar interbody fusions, our findings suggest the cervical spine may behave biomechanically differently. Further investigations are warranted on the utility of HU in the cervical spine.

ID: 2777

RF075: Defining the minimal clinical important change for degenerative cervical radiculopathy assosiated headache (DCR-HA): A study based on data from the Norwegian Registry for Spine Surgery

Samer Habiba ^1,2 , Elisabet Danielsen ³ , Tor Ingebrigtsen ^1,4 , Tore Soldberg ^1,4

¹ Institute of clinical medicine, UiT The Arctic University of Norway, Tromsø, Norway,

² Department of Neurosurgery, University Hospital of North Norway, Tromsø, Norway,

³ Faculty of Health Sciences, UiT The Arctic University of Norway, Tromsø, Norway,

⁴ Department of Neurosurgery and the Norwegian Registry for Spine Surgery (NORspine), University Hospital of North Norway, Tromsø, Norway

Introduction: Previous research have reported that up to 80% of patients undergoing surgery for degenerative cervical radiculopathy (DCR) experience headaches (HA). Yet, this issue has received relatively little attention, and there is a need to quantify if these patients experience meaningful improvements in their headaches after surgical intervention. This study aims to assess the prevalence of HA within a DCR patient cohort, establish the minimal clinical important change (MCIC) for DCR-HA and determine the proportion of patients achieving the MCIC at a 12-month follow-up. Material and Methods: We included a cohort of 6,234 patients consecutively enrolled from the Norwegian Registry for Spine Surgery (NORspine) between 2012 and 2022. All patients underwent anterior cervical surgery for DCR and reported headaches. The MCIC for DCR-HA was determined using the Global Perceived Effect (GPE) scale as an external criterion. The mean Numeric Rating Scale for Headache (NRS-HA) scores at 12 months, the change scores, and the corresponding percentage change scores were analyzed. A cut-off value for the NRS-HA (MCIC) was established by evaluating sensitivity and specificity through a receiver operating characteristic (ROC) curve. Results: The percentage change in NRS-HA had the largest Area Under Curve (AUC) of 0.75 (95% CI: 0.73-0.77). The MCIC for NRS-HA was determined to be a 23.6% improvement, with a sensitivity of 70% and a specificity of 80%. At baseline, 70% of the study population reported DCR-HA. At the 12-month follow-up, 62% of the DCR-HA subgroup achieved the MCIC. Conclusion: The MCIC necessary for patients to perceive a meaningful improvement in headaches post-surgery is 23.6%. Just over half of the DCR-HA population reached this MCIC. Future research should explore whether this threshold alters the rate of surgical success and if DCR-HA is a negative predictor of favorable outcomes post-surgery.

ID: 116

RF076: Epidemiological study of ossification of the posterior longitudinal ligament in Caucasian population at tertiary referral hospital in United Kingdom

Nirup Chandrashekara ¹ , Sudarshan Munigangaiah ¹ , Shashank Chitgopkar ¹ , Jaffaray David ¹ , Sujay Dheerendra ¹ , Jayesh Trivedi ¹

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

Introduction: Ossification of the posterior longitudinal ligament (OPLL) is a condition that exerts a significant influence on individuals affected by it, leading to the constriction of the spinal canal, impairments in neurological function, and a reduction in overall quality of life. Despite being extensively examined within Asian populations, there is a scarcity of research dedicated to investigating OPLL within Caucasian groups, especially within Western tertiary care facilities. This gap in knowledge underscores the importance of conducting more studies to gain a better understanding of the epidemiology, pathophysiology, and optimal management strategies of OPLL in non - Asian populations. This retrospective study provides detailed results from an CT scans investigation carried out in a tertiary hospital facility in the United Kingdom with the primary aim to find the hospital prevalence of OPLL in the Caucasian population. Secondary aim is to know the radiological presentation of the OPLL in Caucasian population in UK. Material and Methods: Our study is a retrospective study design. CT scans of all patients from 1.09.2012. to 1.09.2022 was reviewed and the data that has been collected are the total number of OPLL seen on a CT scan, gender, age, levels of OPLL, number of cervical vertebrae levels involved, size of the OPLL, narrowest spinal canal dimensions, space available for spinal cord, type of OPLL (according to the classification of the Hirabayashi et al.) ,bridging or non-bridging, the level of bridging and if there is any myelopathy or no myelopathy. Other data collected are, if any spinal surgery was done and weather it was anterior or posterior surgery. Results: 43,647 CT was analyzed, and 50 patients had ossification of the posterior longitudinal ligament. Prevalence of OPLL is 0.1% and out of 50 patients, 37 (74%) patients had myelopathy. Type B was the most common at 52%, almost equal distribution between bridging and non-bridging. C4 TO C6 vertebrae was most involved with 18%. Mean size of OPLL was 3.8 mm in C4 & C5 and the highest was at C2, C6 &C7 with 4.8, 4.4 & 4.5 mm respectfully. The least space available for the spinal cord was at C7 with 6.84 mm. Around 39 (78%) of patients had spine surgery and out of 39 patients, 32 patients had posterior spinal surgery. Conclusion: OPLL prevalence in the Caucasian population is 0.1% in United Kingdom, lot less than East Asian population, However Caucasian population became more symptomatic with myelopathy if they had OPLL.

ID: 1727

RF077: Evaluating T2 disc intensity for quantifying spinal disc degeneration

Lukas Schönnagel ¹ , Tim Mihalache ¹ , Paul Köhli ¹ , Bernhard Hoehl ¹ , Daishui Yang ¹ , Hendrik Schmidt ¹ , Pumberger Matthias ¹

¹ Charite Universitätsmedizin Berlin, Berlin, Germany

Objective: An accurate and reliable method of quantifying disc degeneration is crucial in understanding its etiology, progression, and the effect of potential treatment. Reliance on qualitative and subjective classifications can lead to inconsistencies, and their categorial nature limits the detection of small changes. As such, this study aims to establish a quantitative measurement of disc degeneration. Materials and Methods: Patients between 18 and 65 years were prospectively recruited as part of the ongoing DFG Research Unit FOR5177. The intervertebral discs at level L1/2 to L5/S1 were segmented mid-sagittal in T2 weighted sagittal MRIs and divided into five equal regions via custom code. The mean intensity value of the middle regions was then calculated to avoid the inclusion of annulus fibers. This value was divided by the mean intensity value of the cerebrospinal fluid (CSF) at the disc height to account for variations in intensity between MRIs, resulting in a value between 0 and 1. The Pfirrmann Grade of each disc was additionally evaluated. Two different MRI machines were used: the MAGNETOM Lumina (Siemens) and Ingenia (Phillips), with a field strength of 3 and 1.5 tesla, echo time of 100 and 112, and repetition time of 4000 and 3500, respectively, and N4 Bias adjustment was used to reduce the influence of bias field distortion. To test the validity of the CSF adjusted disc intensity (CADI) and the Pfirrman grade, we assessed their association with patient age, as an established risk factor for disc degeneration. We then used linear regression analysis to assess the association between the Pfirrmann Grade and the CADI and to test the difference in the CADI across MRI machines and field strength. Results: A total of 136 patients (56.6% female) were included in the study, with a median age of 43 (IQR 33 to 54). The CSF adjusted intensity value ranged from 0.417 at L1/L2 to 0.38 at L5/S1 and an overall mean value of 0.41. Though both the mean Pfirrmann Grade and mean T2 intensity were significantly associated with age (p < 0.001), the T2 intensity value demonstrated a substantially higher correlation coefficient than the Pfirrmann Grade (0.549 vs. 0.289). The correlation between the T2 intensity value and the Pfirrmann Grade was low to moderate (r² of 0.12 to 0.50), with a large variance in each category. No significant effect of field strength on the CADI was found (p > 0.05). Conclusion: This study demonstrates that the CSF adjusted disc intensity value correlates more strongly with patient age compared to the classical Pfirrmann Grade, suggesting a more accurate method of capturing the extend of disc degeneration. The considerable heterogeneity and overlap of CADI values across different Pfirrmann Grades underscores the heterogeneity inherent to this classification.

ID: 363

RF078: Management of thoracic disc herniations; surgical outcome and algorithm based on a consecutive case series of 275 patients

Mark Arts ¹

¹ Haaglanden Medical Center, The Hague, Netherlands

Introduction: The optimal surgical treatment of thoracic disc herniations remains controversial and depends upon the consistency of the herniation and its location related to the spinal cord. Most patients are treated from anterolateral through a mini-transthoracic approach (mini-TTA) or posterolateral through a transfacet approach. We analysed a large consecutive single center cohort of patients with thoracic disc herniations and proposed a surgical algorithm based on our clinical experience. Material and Methods: In the period 2005 - 2024, 275 patients with symptomatic thoracic disc herniations were operated. The localization of the herniated disc in relation to the spinal cord and the consistency of the herniated disc were evaluated by preoperative CT and MRI. Accordingly, patients were being operated from anterior (mini-TTA or manubrium split), or posterior (posterolateral trans facet). Surgical complications and neurological outcome of all patients were documented. Results: Most patients presented with myelopathy or radicular pain. T10T11 was the most frequent level of disc herniation and T2T3 the least frequent. Nearly 60% of the herniated discs were calcified and 75% was larger than 1/3 of the spinal canal. All patients presented with ASIA grade C, D, or ASIA E. The type of surgery was determined by the level of the affected disc, the axial localisation of the herniated disc in relation to the spinal cord, and the presence of calcification; 5 patients were operated anteriorly transsternal, 209 patients were operated anterolateral through mini-TTA, and 61 patients were operated through posterolateral trans facet approach. In some cases, circumferential decompression of the spinal cord was performed. The duration of surgery, blood loss, hospital stay, and complication rate were significantly higher in patients treated with mini-TTA, and were mainly related to the magnitude and consistency of the herniated disc. Postoperatively, nearly half of the patients improved at least one grade on the ASIA scale. At last follow-up, more than 70% of the patients reported good outcome. Conclusion: Surgical treatment of a symptomatic herniated disc contributed to a clinical improvement in most cases. The approach is dependent upon the level, the location of the herniated disc in relation to the spinal cord, and the consistency of the herniated disc. Medially located large calcified discs should be operated though an anterior approach, whereas non-calcified or lateral herniated discs can be treated from posterior. Complication rate is rather high in anteriorly operated patients and mainly related to the presence of calcifications. For optimal treatment of this rare entity, the treatment should be performed in selected centers.

ID: 994

RF079: Associations between MRI image features and inflammatory biomarkers and the occurrence of low back pain in patients with lumbar disc herniation

Xiaolong Chen ¹ , Dongfan Wang ¹ , Zheng Wang ¹ , Peng Cui ¹ , Shibao Lu ¹

¹ Xuanwu Hospital Capital Medical University, Beijing, China

Introduction: While MRI image features and inflammatory biomarkers are frequently used for guiding treatment decisions in patients with lumbar disc herniation (LDH) and low back pain (LBP), our understanding of the connections between these features and LBP remains incomplete. There is a growing interest in the potential significance of MRI image features and inflammatory biomarkers, both for quantification and as emerging therapeutic tools for LBP. The purpose of this study is to investigate the evidence supporting MRI image features and inflammatory biomarkers as predictors of LBP and to determine their relationship with pain intensity. Material and Methods: A series of continuous patients diagnosed with LDH who underwent discectomy surgery at our institution from February 2020 to June 2023 at the author’s institution were categorized into acute LBP (< 12 weeks), chronic LBP (≥ 12 weeks), and non-LBP groups in this prospective cohort study. MRI image features in discogenic, osseous, facetogenic, and paraspinal muscles, as well as inflammatory biomarkers in serum (including CRP (C-reactive protein), ESR (erythrocyte sedimentation rate), PCT (procalcitonin), TNF (tumor necrosis factor), interleukin-1 beta (IL-1β), and IL-6), and paraspinal muscles (including TNF, IL-1β, IL-6, IL-10, and transforming growth factor beta 1 (TGF-β1)). MRI image features and inflammatory biomarkers relation to pain intensity was assessed using the independent t-test, Chi-squared tests, Spearman rank correlation coefficient, and logistic regression test. Results: Compared to the non-LBP group, the chronic LBP group exhibited a higher incidence of intervertebral disc (IVD) degeneration (≥ grade 3) and high-fat infiltration in paraspinal muscles, alongside a significant reduction in the cross-sectional area (CSA) and fatty degeneration of the multifidus muscle. Furthermore, there was a greater expression of IL-6 in serum and TNF in paraspinal muscles in the chronic LBP group and a greater expression of CRP and IL-6 in serum and TNF in paraspinal muscles in the acute LBP group. CSA and fatty degeneration of multifidus muscle were moderately negatively correlated with chronic LBP scores. The expression of TNF and IL-6 in serum and the expression of TNF in the multifidus muscle were moderately correlated with preoperative LBP. IVD degeneration and high-fat infiltration were identified as risk factors for chronic LBP. Conclusion: The results provide evidence that IVD degeneration, high-fat infiltration, and the reduction of CSA in paraspinal muscles were associated with the development of chronic LBP in patients with LDH, and these associations are linked to inflammatory regulation. This deepens our understanding of the etiology and pathophysiology of LBP, potentially leading to improved patient stratification and more targeted interventions.

Keywords: Intervertebral disc; Endplate change; Facet joint; Paraspinal muscle; Inflammation; Low back pain; Lumbar disc herniation

ID: 1227

RF080: Noggin expression in human nucleus pulposus cells: a comparative study of degenerative and healthy intervertebral discs

Shuimu Chen ^1,2,3 , Sebastian Bigdon ⁴ , Sonja Häckel ⁴ , Christoph Albers ⁴ , Zhen Li ⁵ , Benjamin Gantenbein ^2,4

¹ University of Bern, Department of Orthopedic Surgery & Traumatology, Inselspital, Tissue Engineering for Orthopedics & Mechanobiology (TOM), Bone & Joint Program, Department for BioMedical Research (DBMR), Faculty of Medicine, Bern, Switzerland,

² University of Bern, Tissue Engineering for Orthopedics & Mechanobiology (TOM), Bone & Joint Program, Department for BioMedical Research (DBMR), Faculty of Medicine, Bern, Switzerland,

³ University of Bern, Graduate School for Cellular and Biomedical Sciences (GCB), Bern, Switzerland,

⁴ University of Bern, Department of Orthopedic Surgery & Traumatology, Inselspital, Bern, Switzerland,

⁵ AO Research Institute, Davos, Switzerland

Introduction: Low back pain (LBP) is a health issue that leads to considerable disability and socioeconomic burdens. The degeneration of the human intervertebral disc (IVD) is a key factor in the pathogenesis of LBP. During disc degeneration, the nucleus pulposus (NP), a critical component of IVD, undergoes significant alterations in structural composition and function. Recent studies have highlighted the importance of various genes in IVD health. Noggin has been described as an essential gene in nucleus pulposus cells (NPCs) and a central role in inhibiting osteogenesis. In this study, we conducted a comparative analysis of Noggin expression in human NPCs from degenerative and healthy IVD. Material and Methods: Twenty-six IVD samples (nineteen from degeneration and seven from trauma) were collected to isolate NPCs for RNA extraction. Noggin expression was quantified at the transcript level by qPCR to analyze the difference between degenerative and healthy IVD. Results: Results indicated that Noggin expression was lower in NPCs from degenerated IVD compared to trauma cases. The severity of IVD degeneration correlated with decreased Noggin levels. Healthy males exhibited higher Noggin expression than healthy females and those with IVD degeneration. Noggin expression peaked in young adults (18-45y), decreased in middle age (46-69y), and rose again in the elderly (over 69y), but remained lower than in youth. Furthermore, upper lumbar discs (T12/L1-L2/3) showed higher Noggin levels than lower lumbar discs (L3/4/-L5/S1). Conclusion: This research elucidates valuable insights into the variability of Noggin concerning sex, age, degree of disc degeneration and disc location. It provides implications for IVD health and LBP treatment.

ID: 1949

RF081: Not so indolent: a prospective analysis of Cutibacterium acnes prevalence in degenerative disc tissue

Logan Lake ¹ , Esha Reddy ² , Paul McMillan ¹ , Isaac Hale ¹ , Anthony Guanciale ¹

¹ University of Cincinnati College of Medicine, University of Cincinnati Department of Orthopaedic Surgery, Cincinnati, United States,

² University of Cincinnati College of Medicine, Cincinnati, United States

Introduction: Back pain represents a significant functional, psychological, and socioeconomic burden for millions of individuals worldwide. Degenerative disc disease (DDD), a common reason for surgical spinal decompression, often results from age-related spinal changes. Recent research suggests that Cutibacterium acnes (C. acnes), a low-virulence bacterium, may play a role in this pathogenesis. This study aims to evaluate the prevalence of C. acnes in disc samples from DDD patients and identify associated risk factors. Material and Methods: This prospective observational study included patients treated by a single academic orthopedic spine surgeon between May 2021 and June 2024, all diagnosed with DDD and undergoing elective discectomy or microdiscectomy. Patients with a history of spine surgery (HSS) and those undergoing their first procedure were enrolled. General medical history and demographics were collected via chart review. Using strict antiseptic protocols, a standard surgical approach was employed for exposure, decompression, and disc sample collection, which were sent to the microbiology lab under sterile conditions. Samples were incubated for 14-days and assessed for bacterial growth, with quantitative PCR used to confirm positive cultures. Statistical analysis employed the independent samples t-test and chi-square, with significance defined as p < 0.05. Results: Intervertebral disc samples were collected from 208 patients. Samples from the paraspinal musculature served as internal controls to detect contamination. Ninety-two patients had a history of at least one prior spine surgery, and 166 underwent spine surgery for the first time. On average, primary surgical candidates (PSCs) were younger than patients with a HSS (49.33 ± 14.08 vs 58.87 ± 11.59 years, respectively; p < 0.001). No other patient characteristics differed significantly between PSCs and those with HSS. Interestingly, 22.41% (26/116) of disc samples from PSCs resulted in bacterial growth, significantly higher than the 10.87% (10/92) rate observed for patients with HSS (p = 0.041). No control samples returned a positive culture. Among first-time patients, 22 grew C. acnes (18.97%), 3 grew isolated Staphylococcus epidermidis (2.59%), and 1 grew Corynebacterium striatum (< 1%). The population of PSCs that grew C. acnes was compared to those who demonstrated no culture growth (n = 90). There were no statistically significant differences between the groups in terms of mean age, BMI, race, smoking history, acne history, history of epidural spinal injections, recent antibiotic use, disc level, or Modic score. Our results demonstrated a higher incidence of C. acnes growth in males (p = 0.030), with male sex identified as a risk factor (RR = 3.214, 95% CI 1.193-8.662) for culture growth, and female sex identified as a protective factor (RR = 0.390, 95% CI 0.172-0.883). Conclusion: Our findings indicate positive bacterial cultures are a result of true indolent disc infection rather than specimen contamination. Additionally, we show male sex as a significant risk factor for C. acnes infection, underscoring the need for investigation of the biological mechanism behind this association. Future research should focus on developing diagnostic tools for early identification of indolent infections and on targeted interventions for prevention of DDD progression.

ID: 1721

RF082: Assessing the impact of degenerative disc disease on lumbar mobility

Lukas Schönnagel ¹ , Hendrik Dörfer ¹ , Luis Becker ¹ , Lea Cordes ¹ , Daishui Yang ¹ , Lukas Moedl ¹ , Pumberger Matthias ¹ , Hendrik Schmidt ²

¹ Universitätsmedizin Charite, Orthoppedics, Berlin, Germany,

² Universitätsmedizin Charite, Biomechanics, Berlin, Germany

Objective: Lumbar disc degeneration is a common pathology and a major cause of pain and disability globally. This study aims to analyze the relationship between degenerative disc disease and lumbar mobility via a multivariable analysis. Materials and Methods: Patients between 18 and 64 years of age were prospectively enrolled, as part of the ongoing DFG Research Unit FOR5177. Patients with malignant or immunomodulatory disease or former vertebral fractures were excluded. Intervertebral disc degeneration was rated according to the Pfirrmann classification at each lumbar level (L1/2 to L5/S1). Additionally, a combined lumbar Pfirrmann Grade was calculated by adding the Pfirrmann Grade of each lumbar level. Spinal mobility was assessed non-invasively using a handheld device that is rolled along the spine, employing a gyroscope to track and measure spinal position. It was calculated as the difference in position between the extended and flexed spine. The association between disc degeneration and spinal mobility was analyzed via a uni- and multivariable linear regression model. The multivariable model included age, sex, body mass index (BMI), and low back pain intensity and duration as relevant confounders. Results: After exclusions, 347 patients (43.5% female) with a median age of 46 (35 - 54) were included in the study. The median lumbar and thoracic mobility was 48° (41° - 56°) and 50° (41° to 60°), respectively. The highest degree of disc degeneration was seen at L5/S1, with a median of 2 (2-3), while the median combined lumbar Pfirrmann Grade was 10 (7 - 12). In the univariable analysis, the Pfirrmann Grade of each lumbar level demonstrated a significant correlation with the lumbar spinal mobility (p < 0.001). In contrast, only the L1/2 and L2/3 levels were significantly associated with thoracic mobility (p < 0.001 and p = 0.005). After adjusting for described confounders, only the association between L5/S1 level (β: -1.39, 95% CI: -2.57 - -0.21, p = 0.022) and combined lumbar Pfirrmann grade (β: -0.52, 95% CI: -0.95 - -0.08, p = 0.019), remained significant. The β-Coefficient means that with each increase in the Pfirrmann Grade at L5/S1, the lumbar mobility was reduced by 1.39 degrees. Discussion: Our study demonstrates a significant relationship between lumbar disc degeneration and reduced spinal mobility, particularly at the L5/S1 level and the combined lumbar Pfirrmann grade. No association with thoracic mobility was found after adjustment, suggesting a localized effect of disc degeneration on spinal mobility.

ID: 1666

RF083: Correlation between osteoporosis and endplate damage in degenerative disc disease patients: a study based on phantom-less quantitative compusted tomography and total endplate scores

Yiming Zhang ^1,2 , Yichen Wang ^2,3 , Qiang Yang ^2, Chao Chen ¹

¹ Tianjin Medical University, Tianjin, China,

² Tianjin University Tianjin Hospital, Tianjin, China,

³ Tianjin University, Tianjin, China

Objective: Osteoporosis and degenerative disc disease (DDD) are two common diseases in the elderly population. Endplate damage is a significant trigger and typical manifestation of DDD. This study aimed to investigate the relationship between osteoporosis and endplate damage using PL-QCT and TEPS as measurement tools. Methods: This retrospective study included 205 patients with DDD who were treated at our hospital from January 2019 to May 2022. We collected data on age, sex, body mass index (BMI), PL-QCT values, and total endplate scores (TEPS). The average PL-QCT value of L1-L4 and TEPS were used to represent volumetric bone mineral density (v-BMD) and the degree of endplate damage, respectively. Based on the average PL-QCT value of L1 and L2, patients were divided into three groups: normal group (BMD > 120 mg/cm³), osteopenic group (80 mg/cm³ ≤ BMD ≤ 120 mg/cm³), and osteoporosis group (BMD < 80 mg/cm³). Multiple linear regression models were used to identify independent factors associated with endplate damage. Results: The overall TEPS (4.3 ± 1.3 vs 5.0 ± 1.0 vs 5.9 ± 1.5, p < 0.01) and segment (L1/2-L4/5) TEPS (p < 0.05) in each group showed significant differences, increasing in order from normal group to osteoporosis group. A significant negative correlation was found between TEPS and PL-QCT values in overall and each segments (p < 0.001). The PL-QCT values and age (p < 0.05) were independent factors influencing endplate damage. Conclusions: Our study confirmed a significant positive correlation between osteoporosis and endplate damage. We used a more refined osteoporosis grouping to reveal the importance of preventative protection for patients with osteopenia. Therefore, when treating patients with DDD and osteoporosis, clinicians should carefully consider and implement comprehensive treatment plans.

Keywords: Osteoporosis, Degenerative disc disease, DDD, Endplate damage, total endplate scores, TEPS, phantom-less quantitative computed tomography, PL-QCT, volumetric bone mineral density, v-BMD

ID: 1176

RF084: Comparison of clinical outcome of cooled vs conventional radiofrequency ablation of basivertebral nerve in patients with chronic low back pain of discogenic origin - A single blinded randomized control trial

Prabhat Agrawal ¹ , Abhishek Anand ¹

¹ All India Institute of Medical Sciences, Orthopaedics, Patna, India

Introduction: A significant portion of chronic low backache patients experience is of discogenic origin. Nociceptive receptors present on vertebral end plates transmit pain signal through basivertebral nerve. On MRI the presence of MODIC changes depicts underlying inflammatory process. The transmission of pain signals can be interrupted through Radio Frequency Ablation (RFA). Radio waves are employed to produce a current that warms a small section of nerve tissue during RFA. Conventional RFA has shown promising result in the literature in controlling vertebrogenic pain. Here in this study we compared conventional vs cooled RFA with a notion that since tip of cooled radiofrequency probe is cooled by water, which maintains a low temperature and will ablate larger area of vertebral body it may provide better mean clinical difference. Material and Methods: The objective of our investigation was to evaluate the efficacy of conventional and cooled RFA. The study included patients who met the inclusion criteria, which were a black lumbar disc on MRI with chronic axial low back pain that worsened with forward flexion, protracted standing, and sitting. The patients' age was greater than 18 years. To allocate treatment to patients, Block Randomization Technique was implemented. Using a Block size of 4, a randomization sequence was generated, and the sequence was placed in a sealed opaque envelope. MRI findings were used to determine the target area of ablation, and the vertebrae superior and inferior to the afflicted disc were chosen for RFA. Cooled and Conventional RFA probe were used according to patient’s group and ablation was performed according to the decided level. The VAS (Visual Analogue Scale) scale was used to evaluate the procedure's outcome at three and six months, as well as the NRS (Numerical Rating Scale), ODI (Oswers Industry Disability Index), and SF 36 scale at six months. Results: Pre-operatively in both groups there was no significant difference in pain scores. Post-operatively, pain reduction was more pronounced in the conventional method group, but this was non-significant. At the 3-month follow-up, both groups reported similar pain scores, with no significant intergroup difference. The study, however, discovered that the Cooled RFA significantly reduced VAS scores compared to conventional at 6 months, with no significant effects of factors like age, gender, or the level of ablation. The cooled method also showed a significant improvement in the Numeric Rating Scale at 6 months, with no significant effects of other variables. The SF-36 score showed a negative association with the cooled method, while age had a positive effect. Other factors like gender and pain duration were not significant. The Oswestry Disability Index (ODI) score showed a significant increase at 6 months, but male gender is associated with lower scores. Conclusion: The result of the study suggests that RFA significantly improves discogenic pain and improves the quality of life of patients. Cooled RFA method can be a potential alternative to conventional method in improving clinical outcomes in the longer term.

ID: 1328

RF085: How big is too big? Predicting the need for surgical or conservative treatment in PIVD, based on MRI findings

Venkatesh Dasari ¹ , Sohael Khan ² , Pradeep K Singh ³ , Kartik Soni ⁴

¹ Saptgiri Hospital, Raipur, India,

² Jawaharlal Nehru Medical College, Wardha MH, India,

³ DR L H Hiranandani Hospital, Powai, Mumbai, India,

⁴ Raipur Institute of Medical Sciences, Raipur, India

Introduction: Two major treatment modalities for Prolapsed Intervertebral disc are: Surgical – decompression & discectomy, and Conservative – Medications & Blocks. While patients having severe pain, severe neurological deficit, and/or cauda equina syndrome are straight forward indicated for surgical management, patients having minimal backache and/or radicular pain, along with minimal or no disc bulge on MRI are treated with conservative modalities. In the middle of this spectrum lie the patients with a variable amount of pain, having a variable size of disc herniation on MRI, and they constitute a ‘grey area’ of treatment modality where a selection of conservative or surgical treatment is purely based on the surgeon’s practice and acumen. There isn’t much evidence that correlates the initial MRI findings with the question of wh treatment modality is required. The rationale of this study is to try to define this ‘grey area’ of decision-making and to find out the role of disc-herniation-related-canal-compromise in the lumbar spine in predicting the need for surgical or conservative treatment in patients. Material and Methods: In this ambi-directional study, 64 patients were enrolee in each group: surgical & non-surgical/conservative groups. These were 64 patients who underwent surgery for prolapsed intervertebral disc and got pain relief, and 64 patients undergoing medical conservative treatment for prolapsed intervertebral disc and got relief. The pre-treatment MRI findings of these patients were studied and various measurements were taken. The various measurements were: the area of herniation of the disc, area of canal area, canal compromise ratio, anteroposterior disc length (AB), anteroposterior canal length (CD), mid-width of the herniated disc (EF), the mid-width spinal canal (GH). All the measurements were done using the OSiriX application for IOS. These measurements were then further studied to establish a predicting value for surgical or conservative management in symptomatic lumbar disc herniation patients. Results: The mean age of the surgical group was 45.26 ± 11.20 years and of the conservative group was 49.43 ± 13.74 years. The mean disc length (5.43 ± 1.11 mm), mid-width of the herniated disc (5.64 ± 0.98 mm), mean disc area (211.78 ± 6.60 sq.mm), and canal compromise ratio (0.453 ± 0.015) of the surgical group were found significantly higher than the conservative group. Conclusion: The results of this study can be considered to establish radiological criteria for selecting optimal management options for PIVD. The study suggests that of the patients presenting with symptomatic single-level intervertebral disc herniations, patients whose initial imaging showed:

1. Larger disc herniation length (5.43 ±1.11 mm)

2. Lager disc herniation area (211.78 ± 6.60 mm)

3. Smaller canal cross-section area (467.50 ± 4.61 mm2)

4. Larger canal compromise ratio (0.453 ± 0.015) are more likely to fail with conservative treatment and hence can be advised surgical interventions as first line.

ID: 1109

RF086: Systematic review and meta-analysis of surgical approaches and procedures for thoracic discectomies

Kendra Cooper ^1,2 , Rakesh Kumar ¹ , Aiyush Bansal ¹ , Venu Nemani ¹ , Jean Christophe Leveque ¹ , Rajiv Sethi ¹ , Philip Louie ¹

¹ Virginia Mason Medical Center, Seattle, United States,

² University of Washington, Seattle, United States

Introduction: Thoracic disc herniation (TDH) is a rare condition, comprising only 0.25%-0.75% of symptomatic disc herniations. Surgical resection of TDH presents significant challenges due to the complexity of operating in the thoracic spine and the high potential for complications. Various surgical approaches, including anterior, lateral, and posterior, have been developed, each with distinct advantages and risks. However, no consensus exists on the optimal approach. Methods: A systematic review and meta-analysis were conducted according to PRISMA guidelines, with three reviewers independently screening studies from PubMed, Embase, and Google Scholar. Inclusion criteria were studies reporting complication rates stratified by approach (anterior, lateral, posterior) and procedure (MIS, open, endoscopic, VATS), along with the number of cases and follow-up period. Exclusion criteria were studies that did not meet these reporting standards. A total of 10 articles (390 cases) were identified for the anterior approach, 6 articles (196 cases) for the lateral approach, and 46 articles (1259 cases) for the posterior approach. Random effects models were used to calculate mean complication rates per case-year with 95% confidence intervals (CIs). Subgroup differences by approach and procedure were also analyzed. Results: The meta-analysis revealed the following mean complication rates by approach: anterior approach 0.09 (95% CI [0.06, 0.11]), lateral approach 0.17 (95% CI [0.08, 0.25]), and posterior approach 0.03 (95% CI [0.02, 0.04]). Significant differences were found between anterior and posterior approaches (Δ = 0.0531, 95% CI [0.0283, 0.0778], p < 0.0001), and between lateral and posterior approaches (Δ = 0.0955, 95% CI [0.0515, 0.1395], p < 0.0001). For procedures, MIS was 0.12 (95% CI [0.07, 0.18]), open was 0.05 (95% CI [0.04, 0.07]), endoscopic was 0.01 (95% CI [0.01, 0.02]), and VATS was 0.07 (95% CI [0.04, 0.10]). MIS had a significantly higher complication rate compared to both endoscopic (Δ = 0.0724, 95% CI [0.0380, 0.1068], p < 0.0001) and open procedures (Δ = 0.0497, 95% CI [0.0077, 0.0917], p = 0.0203). VATS also had a significantly higher complication rate compared to endoscopic (Δ = 0.0566, 95% CI [0.0343, 0.0789], p < 0.0001). Conclusion: The posterior approach exhibited the lowest complication rates among the different surgical approaches. This suggests that the posterior approach is preferable when minimizing morbidity in TDH surgery. Among the procedural techniques, MIS had the highest complication rate, while the endoscopic approach had the lowest with a significant difference. These findings provide valuable insights for surgical decision-making in TDH management.

ID: 2008

RF087: Similar genotypic and phenotypic changes are preserved across different anatomic locations and in different intervertebral disc degeneration models

Mulati Mieradil ¹ , Shambhavi Bhagwat ¹ , Jie Shen ¹ , Matt Silva ¹ , Brian Van Tine ² , Regis O'keefe ¹ , Matthew Goodwin ¹

¹ Washington University, Department of Orthopedic Surgery, St Louis, United States,

² Washington University, Oncology, St Louis, United States

Introduction: Intervertebral disc (IVD) degeneration is often thought of as resulting from wear and tear/mechanical breakdown. Many current IVD models rely on direct injury to the disc to induce degeneration. However, human disc degeneration is not typically due to traumatic injury, but rather is multifactorial and often times is associated with instability. Further, mouse models that utilize non weight bearing tail discs appear less externally valid. However, tail models can be faster, cheaper, easily replicated, and more predictable than lumbar spine models. Understand that disc degeneration is more than just a mechanical disease, we sought to understand whether there was a common “disc degeneration” pathway by which IVDs underwent degeneration, regardless of method by which degeneration was induced or weight-bearing status. We compared 3 models of degeneration: 1) Direct injury model in a weight-bearing disc (lumbar spine), 2) Direct injury model in a non-weightbearing disc (tail), and 3) Instability model in a weight-bearing disc. We hypothesized that there are common genotypic and phenotypic changes induced during degeneration regardless of weight-bearing status or mechanism. Material and Methods: First, we determined the most common genotypic changes that were preserved across each condition using RNAseq. Then we validated this by demonstrating preserved phenotypic changes across these conditions using histological analyses. All performed w/ WashU/SOM IACUC approval. C57BL/6J mice of 7-9 months were used (each group, n = 15). For lumbar and tail poke, a 27g needle was used (retroperitoneal approach for lumbar spine). For instability, bilateral facets were resected and the supraspinous/interspinous ligament divided. Histological analysis, IF, and RNAseq done at 2, 4, and 8 wks. Sections were stained w/ Safranin O/Fast Green and Picrosirius red; images captured with ZEISS Axiocam 503microscope. Data = mean ± SEM. The study was approved by the local animal care committee and conducted in accordance with national legislation on protection of animals/NIH guideline for the care and use of laboratory animals. Results: To determine if degeneration proceeds via a common preserved pathway, we examined the most common up/downregulated genes/pathways present at 2 wks. Full RNAseq expression profiles demonstrated overlapping, but not identical, up and down regulation of genes/pathways. To account for baseline differences and determine a “common gene set,” we determined the most up- or downregulated genes regardless of mechanism (injury vs instability) or location (tail vs lumbar spine). For each condition we analyzed all genes up- or down-regulated at least five-fold. The top 15 up- or downregulated genes from each were cross-referenced wth the other conditions. Twelve upregulated genes and five down regulated genes were common across all conditions. Supporting this genotype, the phenotypes of each condition were also similar, with only minor differences. Conclusion: We have provided dats suggesting there is a common disc degenerative pathway by which intervertebral discs undergo degeneration, regardless of weight-bearing status or method by which degeneration is induced. We hope to aid in the development of specific treatments that may slow or even reverse these changes. Given that disc disease contributes to almost every spine pathology, development of better treatment for IVD degeneration is critical.

ID: 2050

RF088: Pre-operative vs post-operative depression in micro-lumbar discectomy patients

Vasanth Bharathidasan ¹ , Gowri Nanda ² , Nigil Palliyil ³ , Jim Vellara ³

¹ Amrita School of Medicine, MBBS, Kochi, India,

² Amrita School of Allied Health Sciences, Kochi, India,

³ Amrita Institute of Medical Sciences, Kochi, India

Introduction: One of the most common causes of lower back pain is lumbar disc herniation, which can occur with or without lumbar radiculopathy. Depression and emotional distress are common psychological symptoms associated with chronic lower back pain. We conducted this study to understand better, the impact of micro-lumbar discectomy on emotional distress and mental well-being in patients suffering from chronic back pain. Material and Methods: In 23 patients with lumbar disc herniation who underwent micro-lumbar discectomy at our institution, the quantitative measurement of leg pain (LP) and back pain (BP) was evaluated using the Visual Analog Scale (VAS), the disease-specific disability scale Oswestry Disability Index (ODI), and the degree of depression was measured using the Modified Zung Self-Rating Depression Scale. The values were taken pre-operatively and post-operatively at day 0, 2 weeks, and 3 months and analyzed for significant relations. Results: Out of the 23 patients, pre-operatively 4 patients were normal, while 13 (56.52%) patients were found to be at risk for depression, and 3 (13.04%) had distressed depression. It was found that post-operatively at 2 weeks and 3 months, 22 patients (95.65%) were found to be normal, with only one patient having distressed depression. There was a significant reduction (p < 0.001) in the mean modified Zung score from 24.23 ± 10.56 pre-operatively to 4.91 ± 4.67 at 3 months, showing a significant improvement in the mental health of patients following the procedure. A significant reduction (p < 0.001) in the pre-operative and post-operative mean ODI and VAS scores for both leg and back pain was also seen. The difference between pre-operative mean ODI scores and VAS scores for leg pain and back pain for each Zung Scale Depression category was also found to be significant (p = 0.003 and p = 0.014, respectively). Conclusion: This study proves that increased functional disabilities, quality of life, and perception of pain are associated with depression, and depressive symptoms, which were significantly reduced after the patient underwent a micro-lumbar discectomy. It was also seen that patients with no depressive symptoms pre-operatively had a better post-operative outcome than patients with pre-operative depression symptoms. As a result, we recommend that patients receive psychological and psychiatric evaluations and treatment prior to surgery to improve their post-operative outcomes.

ID: 2115

RF089: Assessment of 24-month arthrodesis following 3-level ACDF in subjects prospectively enrolled in the FUSE IDE Clinical Trial

Joshua Heller ¹ , Pierce Nunley ² , Rahul Shah ³ , Marcus Stone ² , K. Brandon Strenge ⁴ , Daniel Williams ⁵ , Alexander Lemons ⁵ , Gabriel Tender ⁶ , Bruce McCormack ⁷ , Matthew Jenkins ⁸ , April Slee ⁹ , Erik Summerside ⁸

¹ Thomas Jefferson University, Philadelphia, United States,

² Louisiana Spine Institute, Shreveport, United States,

³ Premier Orthopaedic Associates, Vineland, United States,

⁴ Strenge Spine Center, Paducah, United States,

⁵ Pinehurst Surgical Clinic, Pinehurst, United States,

⁶ Louisiana State University, New Orleans, United States,

⁷ University of California San Francisco, San Francisco, United States,

⁸ Providence Medical Technology, Pleasanton, United States,

⁹ New Arch Consulting, Seattle, United States

Introduction: When performing an anterior cervical discectomy and fusion (ACDF), achieving solid arthrodesis helps ensure sustained relief of symptoms from disc degeneration. The rate of successful arthrodesis has been well established in 1- and 2-level ACDF, however, rates for 3-level treatment have been limited to retrospective case series. The FUSE IDE study is a randomized trial where control-arm subjects received ACDF for treatment of symptoms from degenerative disc disease at three levels. The purpose of this analysis is to describe comprehensive radiographic outcomes in this control dataset as derived from both dynamic x-ray and thin slice CT assessed at 24 months after surgery. Material and Methods: Subjects were recruited from 18 sites. Radiographic fusion was determined at 24 months post study treatment. Successful arthrodesis was defined as a range of motion (ROM, dynamic x-ray) < 2° and interbody bridging bone (IBB) across all three segments as well as absence of subsequent surgical intervention (SSI) at any of the index levels. Radiographic outcomes were determined by an independent core imaging lab. Results: At time of interim analysis, a total 57 subjects contributed to study outcomes (58 ± 10 years, 54% female). Fusion success was observed in 15.8% of subjects by month 12 improving to 33.3% by month 24. By 24 months, ROM was < 2° across all treated levels in 40.4% of subjects, where IBB was observed across all levels in 33.3% of subjects. On a per level bases, ROM and IBB decisions were complimentary in 93.8% of levels and incongruent in 6.3% (ROM_yes & IBB_no = 4.9%; ROM_no & IBB_yes = 1.4%). Thirteen subjects (22.8%) with fusion failure required subsequent surgical intervention performed a median 400 days (range = 2-602 days) from study treatment. Conclusion: To the authors’ knowledge, this study is the first prospective randomized clinical trial assessing radiographic outcomes in patients treated with 3-level ACDF. When followed through 24 months, less than half of ACDF subjects achieved composite arthrodesis across all levels with congruent success rates observed between ROM and IBB definitions. The incidence of radiographic pseudarthrosis when assessed as a composite outcome or individual components appears to be far greater when compared to similar quality data for 1- and 2-level treatment. Further analyses need to be done to understand how these radiographic outcomes correlate with relief of initial complaints.

ID: 2016

RF090: Efficacy of combined human allograft and bone marrow aspiration from the iliac crest autograft for anterior lumbar interbody fusion

Majdi Ben Romdhane ¹ , Allain Jerome ¹ , Poignard Alexandre ¹ , Arvieu Robin ¹

¹ Institute of the Parisian Spine, Île-de-France, Paris, France

Introduction: Spinal fusion procedures have been widely employed to alleviate symptoms and stabilize the spine in various degenerative spinal disorders . While the ultimate goal of achieving successful fusion remains consistent across surgical techniques, identifying the ideal osseous graft, having the best safety, efficacy and cost balance stay uncertain and still discussed The quest for a universally superior method is powered by the fact that even the historical gold standard, the iliac crest bone graft (ICBG), is associated with a lot of complications. Ranging from 1 to 39%, and including hematomas, infections, prolonged chronic site pain or sensory deficits, highlighted the exploration of alternative safer techniques and equally effective. With these challenges, our study aimed to evaluate the efficacy of a novel approach that combines the utilization of human allograft treated with Osteopure® process and osseous autograft from bone marrow aspiration from the iliac crest using a trocar in lumbar interbody fusion procedures after one year of follow up, and secondly to identify the associated factors with a successful fusion, and the safety profile of such a technique. Materials and Methods: A total of 58 patients (32 females, 26 males), with an average age of 54 years, undergoing 75 lumbar arthrodesis between March 2021 and 2022, were included in this retrospective study. Pathologies included 75% degenerative conditions (discopathy with or without spondylolisthesis or adult scoliosis) and 25% isthmic spondylolisthesis, with 38.7% at L5-S1 and 29.3% at L4-L5. Interbody instrumentation involved ROI A or AVENUE L cages, optionally combined with anterior plate fixation (ARTHEMIS or PYRAMIDE) or pedicle screws. All patients underwent a one-year postoperative CT scan, with fusion classified by two independent observers according to Bridwell's criteria. Results: Interbody fusion was classified as grade I in 81.3%, grade II in 14.7%, and grade III in 4% of the operated levels. No patient required reoperation for pseudarthrosis. The rate of grade I fusion was unaffected (p > 0.05) by:

• Gender: 77.3% (females) versus 87.1% (males) with no significant difference.

• Treated pathology: 73.3% for isthmic spondylolisthesis versus 83.3% for degenerative conditions.

• Operated level: 75.9% at L5-S1 versus 81.8% at L4-L5 and 85.7% at L3-L4.

• Vertebral endplate preparation with impactor chisel: 75% versus 83.1% with exclusive use of a fenestrated square curette.

• Type of interbody instrumentation: 85.4% with Avenue L cages versus 76.5% with ROI A cages.

• Addition of anterior or lateral plate fixation: 75.9% versus 84.8% with stand-alone cages. All 20 osteosyntheses combining interbody cages with pedicle screws achieved fusion (Bridwell I) in 74% without posterior instrumentation (p = 0.08). No infections, hematomas, or persistent pain at the marrow harvest site were reported, and no femoral cutaneous nerve injuries occurred. Conclusion: The combination of human-derived spongy graft (Ostéopure™) and percutaneous bone marrow autograft harvested via Jamshidi trocar for interbody fusion yields a fusion rate (Bridwell I or II) of 96%, comparable to the gold standard methods of iliac crest graft and BMP usage. This approach offers the advantages of avoiding morbidity associated with bone marrow harvest and significantly reducing financial costs compared to Inductos™, while eliminating previously reported carcinogenic and heterotopic ossification risks.

RF06: RAPID FIRE PRESENTATIONS IN SPANISH/PORTUGUESE

ID: 1079

RF091: Recosan registry of lumbar disc herniation: prospective and multicenter study of 836 patients operated. Comparison of clinical results with open, tubular and endoscopic technique

Marcelo Molina ^1,2 , Ratko Yurac ¹ , Ramón Torres ² , Lucio Gonzales ² , Karen Weissmann ³ , Juan pablo Otto ⁴ , Daniel Lobos ⁵

¹ Clínica Alemana, Ortopedia y Traumatología, Santiago, Chile,

² Instituto Traumatológico, Ortopedia y Traumatología, Santiago, Chile,

³ Clínica MEDS, Ortopedia y Traumatología, Santiago, Chile,

⁴ Hospital Dipreca, Ortopedia y Traumatología, Santiago, Chile,

⁵ Hospital Sótero del Rio, Ortopedia y Traumatología, Santiago, Chile

Introduction: The Santiago Spine Surgery Registry, RECOSAN, is the first national, prospective, and multicenter registry that contains standardized information on spine surgeries in Chile. The Lumbar Disc Herniation (LDH) is the most common cause of spinal surgery. The aim is to analyze the epidemiological characteristics, surgical techniques, and complications of LDH operations in healthcare centers in Chile. Method: This analytical, prospective, multicenter study was conducted across 10 hospitals and clinics in Santiago from September 2020 to June 2024, including patients diagnosed with lumbar disc herniation. The study evaluated epidemiology, surgical parameters, complications, and the one-month post-surgery outcomes of three discectomy techniques: open (O), tubular (T), and endoscopic (EN), as well as the general average (G). The statistical analysis was done using SPSS, with a significance level of p > 0.05. Results: Out of 2204 surgeries, 770 were for lumbar LDH (34%). Of these, 55% were men, with an average age of 45 years. 85% of patients had primary LDH, while 15% had recurrent LDH. Among those with recurrent LDH, 31% required fusion surgery. In terms of surgical techniques, 57% were performed using open technique (442 patients), 30% using tubular technique T (233 patients), and 13% using endoscopic technique (95 patients). The results for O, T, EN techniques and G average were compared in terms of bleeding, surgical time, intraoperative complications, complications one month post-operation, medical complications one month post-operation, and length of hospital stay. Only mild statistical difference was found in bleeding and number of days hospitalized, with p < 0.05. Conclusion: Lumbar Disc Herniation is the most common cause of spinal surgery, accounting for 34% of the patients. Of these cases, 85% of cases are primary hernias and 15% are recurrent. 31% of recurrent LDHs required fusion. There are three discectomy techniques, open, tubular and endoscopic with no significant clinical differences between them. This is the first prospective, multicenter registry of LDH surgeries in Chile. It outlines the epidemiology and describes the three surgical techniques in relation to surgical variables, complications, and hospital stay.

ID: 995

RF092: Estenocol: does the indirect instability criteria provide a clear decision for adding arthrodesis to decompression in lumbar degenerative stenosis?

Marcelo Molina ^1,2,3 , Jose Dangond ⁴ , Alfredo Guiroy ⁵ , Gonzalo Kido ⁶ , Lucio Gonzales ⁷ , Michael Dittmar ⁸ , Cristobal Carvajal ³

¹ Clinica Alemana, Traumatología, Santiago, Chile,

² Instituto Traumatológico, Traumatología, Santiago, Chile,

³ Universidad Finis Terrae, Santiago, Chile,

⁴ Fundación Clínica Campbell, Ortopedia, Barranquilla, Colombia,

⁵ Clínica Cuyo, Neurocirugía, Mendoza, Argentina,

⁶ Hospital Italiano, Ortopedia, Buenos Aires, Argentina,

⁷ Instituto Traumatológico, Ortopedia, Santiago, Chile,

⁸ Universidad de Guadalajara, Ortopedia, Guadalajara, Mexico

Introduction: In degenerative lumbar stenosis (DLS), various pathological findings such as spondylolisthesis, scoliosis, joint effusion, facet sagittalization, and facet cysts are observed. Some authors suggest performing arthrodesis for these findings, which are considered “indirect” effects of instability. The objective of this study is to assess the clinical outcomes of patients who underwent surgery for DLS and presented with these indirect criteria of instability based on the surgical technique used. Material and Method: This was an analytical, prospective, and multicenter study involving patients with DLS who underwent surgery in seven Latin American hospitals. The RedCap Database of the Lumbar Spine Stenosis project (STENOCOL) was utilized for data collection. The study considered the diagnosis, presence of “instability criteria,” and the results of surgical treatment based on two surgical techniques: pure decompression (PD) and decompression plus arthrodesis (DA). The results were evaluated using the ODI (Oswestry Disability Index), SF-36, PHQ-9, VAS pain score, as well as intra and post-operative complications. The follow-up period was 2 years. Statistical analysis was performed using SPSS with a significance level of p < 0.05. Results: A total of 136 patients underwent surgery, with 61 undergoing PD and 75 undergoing DA. The results were analyzed in two subgroups based on the presence or absence of the following “instability criteria”: spondylolisthesis, scoliosis, joint effusion, facet sagittalization, and facet cysts. No statistically significant differences were found between the two surgical techniques for each “indirect instability” criterion based on ODI, SF-36, PHQ-9, lumbar pain, VAS for leg pain, intra and post-operative complications (p > 0.05). Conclusion: The study revealed that there were no significant differences between the pure decompression and decompression plus arthrodesis groups in patients with DLS and indirect instability criteria. The study did not find any specific indicators of “indirect instability criteria” to determine which patients would benefit from undergoing arthrodesis for DLS.

ID: 952

RF093: Study of cervical kyphosis post-laminoplasty

Vitor Viana Bonan de Aguiar ¹ , Emilson Camapum ¹ , Alex Oliveira de Araujo ² , Ricardo de Amoreira Gepp ¹ , Asdrubal Falavigna ³

¹ Sarah Network of Rehabilitation Hospitals, Neurosurgery, Brasília, Brazil,

² Sarah Network of Rehabilitation Hospitals, Orthopaedics, Brasília, Brazil,

³ University of Caxias do Sul, Neurosurgery, Caxias do Sul, Brazil

Introduction: Spondylotic cervical myelopathy typically requires surgical treatment, and one option is cervical laminoplasty. However, kyphosis can be a potential complication after this procedure and is linked to poorer clinical outcomes. The aim is to assess the effectiveness of various preoperative cervical alignment parameters in identifying patients who are at a higher risk of developing kyphosis after undergoing cervical laminoplasty. Material and Methods: Patients who underwent open-door cervical laminoplasty for spondylotic cervical myelopathy were retrospectively assessed before and after surgery, with a minimum follow-up period of 2 years. Cervical radiographs were taken before and after surgery in an upright position with the head in a neutral profile. Various cervical sagittal alignment parameters were then calculated, including the Cobb angle C2-C7, Cobb C0-C2, C2 slop, cervical sagittal vertical axis, T1 slop, and the mismatch or discrepancy between T1 slop and cervical lordosis. The thoracic inlet angle (TIA) was determined using a T1-weighted MRI. Patients who were previously lordotic were divided into two groups based on whether they developed postoperative kyphosis, defined by a Cobb angle between C2 and C7 of less than zero, and their preoperative variables were compared. Results: A total of 101 patients were evaluated, with a mean age of 53.4 years and 62.3% being men. The average follow-up time between surgery and the last radiography evaluated was 6.8 ± 3.5 years, ranging from 2 to 18.2 years. On average, there was a loss of -4.3° ± 9.5° of cervical lordosis between C2-C7, with a p-value of 0.0774. Out of the 101 patients, 7 already had kyphosis before the surgery. Among the 94 lordotic patients, 10 developed kyphosis after laminoplasty (10.6%). Before surgery, this group showed, on average, a greater cervical mismatch (19.6° vs. 11.6°; p-value 0.0030) and a greater C2 inclination (18.9° vs. 9.9°; p-value 0.0009). An analysis of the Receiver Operating Characteristic (ROC) curve identified a satisfactory area on the curve of 0.8 for both measurements, with angulations of 22.4° of cervical mismatch and 19.6° of C2 inclination being points of adequate cutoff to predict kyphosis after laminoplasty, with 96.4% and 91.7% specificity, respectively. In the series, no patient underwent reoperation until the last evaluation. Conclusion: This study highlights the importance of preoperative assessment of cervical mismatch and C2 inclination in identifying patients at a higher risk of developing kyphosis after cervical laminoplasty and establishes cutoff points with high diagnostic accuracy.

ID: 1075

RF094: Risk factors for degenerative lumbar stenosis: a Ibero-American multicenter case-control study

Gabriel Alonso Cuéllar ¹ , Nicolás Prada Ramírez ¹ , Jorge Ramirez ¹ , José Rugeles ¹ , Carolina Ramirez ¹ , Viviana Plazas Bedoya ² , Diego Muñoz Suárez ³ , Vladimir Sánchez ⁴ , Yajaira Castro ¹

¹ LESS Invasiva Academy, Research & Education, Bogotá, Colombia, ² Clínica Reina Sofía, Bogotá, Colombia, ³ Clínica Foscal Internacional, Bucaramanga, Colombia, ⁴ Hospital Nacional arzobispo Loayza-MINSA, Lima, Peru

Introduction: Ibero-American population, as in the rest of the world, has increased its life expectancy. This impact on longevity and the demographic explosion have created fundamental challenges for medical science. In this regard, one of the challenges for public health focuses on improving predictive, diagnostic, and treatment tools for chronic non-infectious diseases with low mortality, such as degenerative lumbar spinal stenosis (LSS). Due to its chronic and degenerative nature, one of the primary management strategies is preventing risk factors (RF). Some recent studies have reported abdominal obesity, hypertension, diabetes, dyslipidemia, high BMI (body mass index), facet tropism, and occupations related to excessive physical exertion. Most of these investigations have been carried out in countries such as Italy, Japan and the United States, and to date, studies have yet to determine whether there is any particularity in the development of LSS in the Ibero-American population. The primary purpose of this retrospective multicentric study is to evaluate the association of a series of demographic, medical and degenerative conditions with the presentation of degenerative lumbar stenosis in patients from different centers in Colombia, Ecuador, Mexico, Peru, and Spain. Material and Methods: This retrospective multicenter case-control study was carried out between August 2022 and August 2023. The seven center that participated in the study were at seven Ibero-American cities: Bogotá, Bucaramanga, Duitama, Lima, Quito, Mexico City, and Barcelona. According to their imaging studies, the patients were assigned to each of the two groups: the case group corresponded to patients with symptoms related to LSS. Diagnosis of lumbar stenosis was confirmed by a spine surgeons expert using the MRI images in all cases and according NASS guidelines. Results: A total of 270 patients from clinical centers located in five countries of the Ibero-American region were analyzed. 136 patients met the inclusion criteria and were in the lumbar spinal stenosis (LSS) group (cases). The control group was made up of individual who consulted for signs and symptoms other than those related to low back pain and were 134 individuals. The groups did not differ significantly in sex, BMI (body mass index), or weight. Statistically significant differences were found in the age of the groups (56.8 years vs 52.02 years; p = 0.0140). No risk factor related to patient occupation was found to be statistically significant. Multivariate analysis showed a strong association between the presence of scoliosis (p = 0.001; OR 12.6 CI 2.9-55.4), instability (p = 0.005; OR 4.9 CI 1.6-14.9), and facet trophism (p = 0.001; OR 4.2 CI 17-10.1) with the presentation of lumbar stenosis. Radiculopathy proved to be a symptom highly related to lumbar stenosis. Conclusion: There are strong association between the degenerative pathologies of the spine and LSS. This study found no relationship between habits, history, occupation, and age as risk factor for developing LSS in Ibero-American patients.

ID: 2433

RF095: Inter- and intraobserver reliabilities of proximal femur maturity index for staging skeletal growth

Dante Escobar ¹ , Maria Celeste Zamora ¹ , Marcelo Alejandro Valacco ¹ , Felix Imposti ¹ , Mariano Servidio ¹

¹ Complejo Medico Churruca Visca, CABA, Argentina

Introduction: The predictors of skeletal maturity guide the treatment of idiopathic scoliosis by the risk and timing of curve progression. Skeletal maturity status can be a crucial factor for treatment prognosis and an indicator for the risk of curve progression. There are multiple skeletal maturity measures currently in use for assessing growth, including Risser staging, triradiate cartilage closure, Sanders staging, the distal radius and ulna classification, and the proximal humeral ossification system. The purpose of this study was to determine the inter and intraobserver reliabilities of the Proximal Femur Maturity index (PFMI) for Staging skeletal Growth. Material and Methods: Data from a consecutive series of 45 spine radiographs from a data base were evaluated retrospectively. 27 were female and 18 were male patients. The inclusion criteria were patients < 20 years of age, skeletal immaturity and who had complete spinograms including both hips. The corresponding image material was presented in random order. To determine interobserver reliability, the five raters rated the images separately. The raters had different levels of training, 2 senior surgeons, with more than 15 years of experience, 2 junior surgeons with less of 15 years of experience, and 1 fellow. At 4 week later, the same image material was assessed again in a different order by the same surgeon to determine the intraobserver reliability. The weighted kappa coefficient (wκ) was used to determine the interobserver and intraobserver agreement. Results: The interobserver agreement was moderate, wκ = 0.66. The values for intra observer agreement was for the observer 1 and 2 with > 15 of experience wk = 0.65 and wk = 0.72. For surgeon with < 15 of experience, observer 3 and 4, wk: 0.69 and wk: 0.64 respectively. For observer 5; corresponding to fellow was wk = 0.73. Conclusion: In this single center study, we reported moderate interobserver (wk: 0.66) agreement and variable intra observer agreement (wk: 0.64 to wk: 0.73). Levels of training did not imply a better agreement.

ID: 957

RF096: Population clusters and the risk of low back pain in the adult population from an unsupervised analysis of the 2016 - 2017 National Health Survery

Francisco Fernandez Schlein ¹ , Mauricio Campos ¹ , Maria Jesus Lira ¹ , Jose Lira ¹

¹ Pontificia Universidad Catolica de Chile, Orthopedic Surgery, Santiago, Chile

Introduction: Low back pain (LBP) is one of the leading causes of disability-adjusted life years (DALYs) and work absenteeism, underscoring the need to identify specific characteristics of at-risk subpopulations. In this context, the objective of the present study was to evaluate the risk of LBP using a cluster analysis of the adult population. Material and Methods: A cross-sectional study was conducted employing unsupervised machine learning techniques on data from the National Chilean Health Survey (ENS) 2016–2017. Dataset preprocessing involved coding categorical and ordinal variables, followed by normalization. Several techniques were applied to reduce variable dimensions prior to clustering: initially, a manual selection of important variables was conducted, followed by the removal of redundant factors based on variance, collinearity, and agreement with LBP. The XGBoost algorithm was used as a regression model to identify the most important predictors of back pain, which were subsequently used in the cluster analysis. Clustering was performed using the K-prototype algorithm due to the mixed nature of the data. The optimal number of clusters was determined using Silhouette and Davies-Bouldin indices. LBP prevalence was then compared across clusters, and multivariate regression was performed with variables previously selected. Statistical significance was set at p < 0.05. All computations were carried out using Python version 3.8 and Stata version 17.0. Results: The overall prevalence of low back pain was 20.4% (95% CI, 18.2-22.8%). Three distinct clusters (A, B, and C) were identified. Compared to Cluster A, both Clusters B and Cluster C exhibited a 1.6-fold increased risk of LBP (A vs. B: OR 1.02-2.5, p = 0.037; A vs. C: OR 1.2-2.3, p = 0.006). No significant differences in LBP prevalence were observed between Clusters B and C (p > 0.05). In the multivariate analysis, Cluster A demonstrated a significantly lower prevalence of hypovitaminosis D (17.1%) compared to Clusters B (23.8%) and C (23.5%). Additionally, the mean waist circumference was significantly smaller in Cluster A (93.9 cm) than in Clusters B (96.1 cm) and C (96.3 cm). Differences were also observed between Clusters A and C in terms of engaging in work or strenuous physical activity (13.5% in Cluster A vs. 17.5% in Cluster C; p-value < 0.05). Depression prevalence was higher in Cluster C (17.4%) compared to Cluster A (12.8%; p-value < 0.05). Conclusion: The risk of LBP varies among the clusters derived from the ENS dataset. The cluster with the lowest prevalence of LBP exhibited lower rates of hypovitaminosis D, fewer individuals with suspected depression, a smaller proportion of those engaged in physically strenuous occupations, and smaller waist circumferences. Assessing LBP prevalence based on these risk clusters may offer valuable insights for the development of targeted preventive programs tailored to specific subpopulations.

ID: 1639

RF097: Use of SPECT/CT in apparently aseptic spinal revisions: a case series

Matias Leonardo Cullari ¹ , Juan Ignacio De Giano ¹ , Facundo Aguirre ¹ , Santiago Aguer ¹ , Ruy LLoyd ¹

¹ British Hospital, Buenos Aires, Argentina

Introduction: Low back pain is a significant health issue associated with substantial economic and social costs. Management of this condition ranges from conservative treatments to more invasive methods. Spinal arthrodesis is performed to enhance spinal stability in various spinal pathologies. Unfortunately, despite spinal fusion surgery, a notable number of patients continue to experience low back pain. Identifying patients who might benefit from additional surgery is thus crucial. One significant cause of persistent pain and reoperation is the loosening of surgical material. Conventional imaging methods can make detecting loosening challenging due to metal artifacts. Bone scintigraphy with SPECT is a valuable tool for these cases as it is not affected by metal artifacts. Additionally, hybrid imaging techniques combining SPECT and CT have greatly improved the anatomical localization of anomalies found in SPECT. Recent studies suggest that screw loosening may be associated with chronic low-virulence infection at the surgical implant. These bacteria often form biofilms, which can decrease sensitivity to conventional culture methods. The use of sonication to retrieved inert material before culturing disrupts the biofilm and results in significantly higher recovery of bacterial growth. This study aims to present a series of patients who underwent spinal reoperation due to persistent pain, with hypercaptation on SPECT/CT and positive cultures by sonication. Material and Methods: A retrospective analysis was conducted on patients who underwent spinal revision due to postoperative pain without clinical signs of infection. Clinical data collected included age, gender, comorbidities, time elapsed from the initial surgery to revision. Additional data included samples sent for sonication analysis, positive cultures by sonication and conventional methods, delay in sonication results, and duration of antibiotic treatment. All patients underwent CT and SPECT/CT to look for signs of loosening. The site of hypercaptation on SPECT/CT was also assessed. The surgeon's impression of material firmness at the time of removal was correlated with SPECT/CT findings, and postoperative complications were recorded. Results: A total of 17 patients were included, with a mean age of 55 years, consisting of 9 men and 8 women. The average time between the initial surgery and revision with material removal was 27.82 months. Of the total patients, 5 (29.41%) had loosening observed in pre-revision CT, and 11 (64.70%) showed hypercaptation in SPECT/CT. A comparative analysis between the surgeon's sense of material firmness at the time of removal and the preoperative SPECT findings showed that 6 patients (35.29%) with intraoperative loosening had previously shown hypercaptation in the same area on SPECT/CT, resulting in a statistically significant correlation (p = 0.04). Nine patients (52.94%) had positive cultures by sonication; of these, 5 (55.55%) had hypercaptation on SPECT/CT (p = 0.61). The microorganisms detected by sonication were: Propionibacterium acnes 5 (55.55%), Staphylococcus warneri 2 (22.22%) Staphylococcus epidermidis 1 (11.11%) Propionibacterium avidum 1 (11.11%). Conclusion: SPECT/CT is an effective tool for detecting surgical material loosening in patients with persistent low back pain following spinal fusion surgery, especially when complemented by sonication cultures to identify chronic infections. The significant correlation between hypercaptation in SPECT/CT and intraoperative loosening highlights its value in preoperative assessment.

ID: 2434

RF098: Correlation between the risser sign and a proximal femur maturity index

Dante Escobar ¹ , Maria Celeste Zamora ¹ , Marcelo Alejandro Valacco ¹ , Felix Imposti ¹ , Mariano Servidio ¹

¹ Complejo Medico Churruca Visca, CABA, Argentina

Introduction: The assessment of skeletal maturity is of great importance in cases of adolescent idiopathic scoliosis because it used to guide treatment and surgical planning. The Risser sign is the skeletal maturity indicator that is preferred for follow-up and it is applied in multicenter studies and multicentric databases. In 2022 a novel Proximal Femur Maturity Index (PFMI) for staging skeletal growth was presented. The present study aimed assessing the correlation of Risser sign with PFMI. Material and Methods: Data from a consecutive series of 45 spine radiographs from a data base were evaluated retrospectively. 27 were female and 18 were male patients. The inclusion criteria were patients < 20 years of age, skeletal immaturity and who had complete spirograms including both hips. The corresponding image material was presented in random order. To determine the correlation, the five participants rated the images separately. The same image was qualified according to Risser and PFMI. The raters had different levels of training, 2 senior surgeons, with more than 15 years of experience, 2 junior surgeons with less of 15 years of experience, and 1 fellow. The relationship between Risser sign and PFMI was investigated using the Kendall Tau-b (K Tau-b) correlation test. Results: The values for intra observer correlation using Kendall Tau-b coefficient versus PFMI were for the observer 1 and 2 with > 15 of experience K Tau-b = 0.55 and K Tau-b = 0.56. For surgeon with < 15 of experience, observer 3 and 4, K Tau-b = 0.68 and K Tau-b = 0.56 respectively. For observer 5; corresponding to fellow was K Tau-b = 0.78. Conclusion: The Risser sign has a very strong correlations with PFMI. The advantages of using these two indices are that both can be measured on the same routine spine radiographs and thus avoiding additional radiation exposure. These two indices can be complementary to make better decisions.

ID: 210

RF099: Spondylolisthesis in children younger than 10 years: who will progress to a high grade slip

Sofía Frank ¹ , Julie Joncas ¹ , Jean-Marc Mac-Thiong ¹ , Soraya Barchi ¹ , Stefan Parent ¹ , Hubert Labelle ¹

¹ CHU Sainte Justine, Orthopedic Surgery, Montréal, Canada

Introduction: The risk of progression for patients younger than 10 years old with spondylolisthesis remains largely unknown, lacking clear guidelines for follow-up. The purpose of this study is to document the progression of spondylolisthesis in children younger than 10 years old, and identify predictors of progression. Material and Methods: We reviewed the radiographs of patients younger than 10 years presenting with a spondylolisthesis at our institution, and who attended at least 1 follow-up visit. The percentage of slip, sacral slope, pelvic tilt, and pelvic incidence were measured. Results: There were 58 girls and 36 boys aged 8.5 ± 1.8 years at initial presentation and 13.7 ± 3.4 years at last follow-up. The mean of follow up was 5.1 ± 3.2 years. There were 91 patients with low-grade spondylolisthesis mean 19.1 ± 10.7 % slip and 3 patients with high-grade spondylolisthesis 80.1 ± 8.5 % slip at the initial presentation. 22 patients (24%) showed a slip progression greater than 10% during follow-up. A significant association was found between the slip % at the initial presentation vs. last follow-up. No associations were found between pelvic parameters and slip progression. At the end of follow-up, 4 children had a slip greater than 50 % and 2 children underwent spondylolisthesis surgery before the age of 10 years and 1 one child at 11 years old. The average age of this group was 9.05 years (5.9-10.6). All of these were girls and all had an initial slip greater than 40° except for one girl whose initial slip was 29% at the age of 5.9 years. Conclusion: Our study has demonstrated that spondylolisthesis in children under 10 years of age may progress. The only factor with a significant positive association with final slip was the degree of initial slip. “Low/high-border subtype” with 40-50% of slip and dysplasia as a new risk factor of progression needs further investigation to validate this finding and to determine the most appropriate follow-up protocols for each patient subgroup.

ID: 578

RF100: Time to surgery for subaxial cervical fractures: a multicenter study

Guisela Quinteros Rivas ¹ , Guillermo Ricciardi ² , Ignacio Cirillo ³ , Edgar Márquez García ⁴ , Juan P. Cabrera Cousiño ⁵ , Charles Carazzo ⁶ , Ratko Yurac ¹ , Alfredo Guiroy ⁷

¹ Clinica Alemana de Santiago, Spine Unit, Orthopedic Department, Santiago, Chile,

² Centro Medico Integral Fitz Roy, Orthopedic and Traumatology, Buenos Aires, Argentina,

³ Hospital del Trabajador, Orthopedic and Traumatology, Santiago, Chile,

⁴ Instituto Mexicano del Seguro Social, Unidad Medica de Alta Especialidad Victorio de la Fuente Narváez, Ciudad de Mexico, Mexico,

⁵ Hospital Clinico Regional de Concepcion, Concepcion, Chile,

⁶ Hospital de Passo Fundo, Rio Grande, Brazil,

⁷ Clinica de Cuyo, Mendoza, Argentina

Introduction: The timing of surgery for subaxial unstable cervical injuries without neurological deficits, especially in polytrauma patients, remains a subject of debate. Prompt surgical decompression is crucial for managing traumatic spinal cord injuries and mitigating their long-term effects. While some cases may necessitate delays in surgical intervention, it is essential to strive for early treatment whenever possible. Updated clinical guidelines advocate for early surgery (within 24 hours), and there is ongoing research exploring even earlier interventions. Therefore, assessing regional practices and developing strategies to facilitate timely treatment is imperative. This study aims to identify delays in the surgical stabilization of subaxial cervical fractures and the primary factors contributing to these delays across Latin America. Material and Methods: This is a retrospective multicenter cohort study of patients surgically treated for subaxial cervical fractures from 13 spine centers across Latin America from January 1th 2014 to January 1th 2023. Causes of delay to surgery beyond 24 hours were documented. Results: We included 529 patients from 13 institutions in Latin American countries: 408 (77.1%) males and 121 (22.9%) females with a mean age of 43.4 (SD = ±16,2). Predominantly caused by traffic accident (n = 256; 48.4%), followed by fall from height (n = 233; 44%). Mostly, suffered type C fractures (n = 348; 65.8%) and/or neurological injury (n = 384; 72.6%). The time from admission to surgery was > 72 hours in 70% of the patients included (n = 375; 70.9%). More than 45% waited longer than a week (n = 257; 48.6%) for spine surgery. Only 12.5% (n = 66) of the patients received surgery in the first 24 hours from admission. The primary reasons for the surgical delay were the necessity for other surgical procedures (n = 161; 34.8%), the unavailability of surgical implants (n = 60; 13.0%), patient clinical instability (n = 55; 11.9%), and delays in referral (n = 38; 8.2%). Conclusion: We documented significant and concerning delays in providing spinal decompression and stabilization surgery to patients with cervical spine fractures. Only 17% of patients have surgery in the recommended time < 24 hrs, more than half of the patients must wait for more than 72 hours, and nearly half of patients wait for longer than a week.

ID: 1178

RF101: Unilateral cervical facet fracture f2 and f3: identifying managment and prognostic factors. a retrospective study

Joaquín Herrera ¹ , Ignacio Cirillo ¹ , Ignacio Farías ¹ , Marcos Gimbernat ¹ , Juan Zamorano ¹ , Carlos Tapia ¹ , Pablo Carreño ¹ , José Via Dorado ¹

¹ Hospital del Trabajador, Santiago, Chile

Introduction: Cervical facet injuries (F2 or F3) pose a complex clinical challenge due to the lack of well-defined stability criteria for guiding treatment, which often relies on subjective factors (1,2). Management strategies and prognosis remain under debate in the literature (2,3). This study aims to describe a series of cases to identify factors that facilitate decision-making in the management and prognosis of these fractures. Material and Methods: A retrospective study of 50 patients with unilateral cervical facet fractures (F2 or F3, AOSpine classification) was conducted at a single trauma center considering patients between 2009 and 2023. The study included 46 males and 4 females aged 21-65 years (mean age 40.1 years, SD 12.7). All patients underwent initial spine CT scans, with MRI and radiographs performed as needed. Management was based on fracture stability and clinical presentation. Patients were categorized into F2/F3 groups and further subdivided based on initial management: orthopedic, emergency surgery (kyphosis >11°, listhesis >3.5 mm, or neurological compromise), and planned surgery. Follow-up included imaging studies and specialist consultation. In cases where conservative management failed (listhesis progression or non-union), surgery was performed. Analyzed variables included the affected segment, listhesis, facet comminution, disc injury, associated injuries, initial neurological status, and final status at follow-up. Results: Fifty patients were diagnosed with cervical facet fractures, with the C6-C7 segment being the most commonly affected (53.06%). Nine patients required emergency surgery (4 in F2, 5 in F3). All patients presented with disc injury, and 7 (77.7%) had listhesis > 2 mm. Among patients receiving orthopedic management, 7 (25%) experienced treatment failure, all of whom exhibited disc injury, facet synovitis, and prevertebral edema. The success rate for conservative treatment differed between groups: 84.2% (16 patients) in the F2 group and 55.5% (5 patients) in the F3 group. None of the patients presented with lasting neurological injuries at follow-up. Conclusion: The presence of disc lesions and facet synovitis, as identified in our results, significantly influences treatment outcomes, underlining the need for tailored approaches to optimize patient care.

ID: 326

RF102: Artificial intelligence assistance for the measurement of full alignment parameters in whole-spine lateral radiographs

Federico Landriel ¹ , Bruno Cruz Franchi ² , Candelaria Mosquiera ² , Fernando Padilla Lichtenberger ¹ , Alfredo Guiroy ³ , Santiago Hem ¹

¹ Hospital Italiano de Buenos Aires, Spine Unit - Neurosurgery, Buenos Aires, Argentina,

² Hospital Italiano de Buenos Aires, Health Informatics, Buenos Aires, Argentina,

³ Clinica de Cuyo, Spine Unit - Neurosurgery, Mendoza, Argentina

Introduction: Measuring spinal alignment with radiological parameters is essential in patients with spinal conditions likely to be treated surgically. These evaluations are not usually included in the radiological report. As a result, spinal surgeons commonly perform the measurement, which is time-consuming and subject to errors. We aim to develop a fully automated artificial intelligence (AI) tool to assist in measuring alignment parameters in whole-spine lateral radiograph (WSL X-rays). Material and Methods: We developed a tool called Vertebrai that automatically calculates the global spinal parameters (GSPs): Pelvic incidence, sacral slope, pelvic tilt, L1-L4 angle, L4-S1 lumbo-pelvic angle, T1 pelvic angle, sagittal vertical axis, cervical lordosis, C1-C2 lordosis, lumbar lordosis, mid-thoracic kyphosis, proximal thoracic kyphosis, global thoracic kyphosis, T1 slope, C2-C7 plummet, spino-sacral angle, C7 tilt, global tilt, spinopelvic tilt, and hip odontoid axis. We assessed human-AI interaction instead of AI performance alone. We compared the time to measure GSP and inter-rater agreement with and without AI assistance. Two institutional datasets were created with 2267 multilabel images for classification and 784 WSL X-rays with reference standard landmark labeled by spinal surgeons. Results: Vertebrai significantly reduced the measurement time comparing spine surgeons with AI assistance and the AI algorithm alone, without human intervention (3 minutes vs. 0.26 minutes; p < 0.05). Vertebrai achieved an average accuracy of 83% in detecting abnormal alignment values, with the sacral slope parameter exhibiting the lowest accuracy at 61.5% and spinopelvic tilt demonstrating the highest accuracy at 100%. Intraclass correlation analysis revealed a high level of correlation and consistency in the global alignment parameters. Conclusion: Vertebrai’s measurements can accurately detect alignment parameters, making it a promising tool for measuring GSP automatically.

Keywords: Artificial intelligence; Deep learning; Spinal parameters; Spine alignment.

ID: 325

RF103: Measuring the delay in the referral of unstable vertebral metastasis to the spine surgeon: a retrospective study in a Latin American Institution

Federico Landriel ¹ , Fernando Padilla Lichtenberger ¹ , Liezel Ulloque-Caamano ² , Candelaria Mosquiera ³ , Santiago Hem ¹

¹ Hospital Italiano de Buenos Aires, Spine Unit - Neurosurgery, Buenos Aires, Argentina,

² Hospital Padilla, Neurosurgery, San Miguel de Tucuman, Argentina,

³ Hospital Italiano de Buenos Aires, Health Informatics, Buenos Aires, Argentina

Introduction: The delay in the referral of patients with potential surgical vertebral metastasis (VM) to the spine surgeon is strongly associated with a worse outcome. The spinal instability neoplastic score (SINS) allows for determining the risk of instability of a spine segment with VM; however, it is almost exclusively used by specialists or residents in neurosurgery or orthopedics. The objective of this work is to report the delay in surgical consultation of patients with potentially unstable and unstable VM (SINS > 6) at our center. Material and Methods: We performed a 5-year single-center retrospective analysis of patients with spine metastasis on computed tomography (CT). Patients were divided into Group 1 (G1), potentially unstable VM (SINS 7-12), and Group 2 (G2), unstable VM (SINS 13-18). Time to surgical referral was calculated as the number of days between the report of the VM in the CT and the first clinical assessment of a spinal surgeon on the medical records. Results: We analyzed 220 CT scans, and 98 met the selection criteria. Group 1 had 85 patients (86.7%) and Group 2 had 13 (13.3%). We observed a mean time to referral of 83.5 days in the entire cohort (std = 127.6); 87.6 days (std = 135.1) for G1, and 57.2 days (std = 53.8) for G2. The delay in referral showed no significant correlation with the SINS score. Conclusion: We report a mean delay of 83.5 days in the surgical referral of VM (SINS > 6, n = 98). Both groups showed cases of serious referral delay, with 25% of patients having the first surgical consultation more than three months after the CT study.

Keywords: Oncological surgical delay; SINS referral delay; spine tumor referral delay; unstable metastasis surgical referral delay.

ID: 1663

RF104: Patients with cervical distractive flexion fractures treated with anterior discectomy and fusion: a retrospective cohort with a minimum follow-up of 2 years

Julio Bassani ¹ , Matias Petracchi ¹ , Carlos Sola ¹ , Gonzalo Kido ¹ , Marcelo Gruenberg ¹

¹ Hospital Italiano de Buenos Aires, Buenos Aires, Argentina

Introduction: There is still controversy regarding the proper management of cervical flexion-distraction fractures, as they can be treated through an anterior approach, posterior approach, or a combination of both. Material and Methods: A retrospective analysis was conducted on 27 patients with flexion-distraction injuries, treated between 2004 and 2020 with anterior cervical arthrodesis, with a minimum follow-up of 2 years. The following were determined: type of injury according to the Allen and Ferguson classification, arthrodesis rate, and prevalence of mechanical failure. The following were also analyzed: sex, age, and affected disc level. Cases without a minimum follow-up of 2 years, patients with cervical ankylosing spondylitis, evident radiological osteoporosis, and signs of diffuse idiopathic skeletal hyperostosis (DISH) were excluded. Results: The median follow-up was 28 months, and 85% of the patients were men with a median age of 34 years. Bilateral facet dislocations accounted for 52% of the cases. Injuries at the C6-C7 level occurred in 45% of the cases. Mature arthrodesis was achieved in 93% of the cases. One case of pseudoarthrosis was recorded, which required revision surgery, and one patient developed segmental kyphosis that stabilized at 10º and remained asymptomatic, so no further surgery was required. Two distal and one proximal asymptomatic adjacent segment syndromes were observed, without the need for active treatment. No implant failures were recorded in the analyzed population. Conclusion: In 93% of our series of patients with cervical flexion-distraction injuries treated with discectomy and anterior arthrodesis, a solid arthrodesis was achieved without the need for a complementary posterior approach. In the absence of vertebral endplate fractures, segmental kyphosis greater than 11º, or anterolisthesis greater than 3.5 mm, “stand-alone” anterior cervical discectomy and arthrodesis is a safe and effective treatment for stage 2 and 3 flexion-distraction injuries.

ID: 1498

RF105: Is cervical imbalance after ACDF a risk factor for the development of adyacent segment degeneration? A retrospective study with an average of 8 years of follow-up

Valentino Latallade ¹ , Matias Pereira Duarte ¹ , Ignacio Sola ¹ , Gonzalo Kido ¹ , Ivan Huespe ¹ , Matias Petracchi ¹ , Marcelo Gruenberg ¹

¹ Hospital Italiano de Buenos Aires, Ciudad Autónoma de Buenos Aires, Argentina

Introduction: There is limited evidence indicating how cervical imbalance following anterior cervical discectomy and fusion (ACDF) may influence the development of adjacent segment degeneration (ASD). The primary objective of this study is to evaluate the hypothesis that postoperative sagittal imbalance influences the development of ASD in patients over 18 years of age who have undergone ACDF. Material and Methods: We retrospectively analyzed a consecutive series of 63 patients with ACDF fusion, with a minimum follow-up of 2 years. Radiological assessment included sagittal balance parameters (C2-C7 segmental lordosis and C2-C7 sagittal vertical axis) and radiographic parameters indicating the development of ASD (proximal intervertebral disc narrowing, proximal intervertebral disc angle, listhesis, and anterior osteophytes). Additionally, a distinction was made between fusion techniques (plate vs. standalone interbody device). Results: In the analysis of postoperative imbalance as a predisposing factor for ASD, we found that patients with postoperative balance had a 26% incidence of adjacent degeneration, compared to 22% in patients without postoperative balance. This difference between groups was not significant (p = 0.7). When comparing the proportion of patients with degeneration between those operated on with a plate versus those operated on with a standalone interbody device, 23% of patients with a plate showed degeneration, compared to 27% of patients with the interbody device, with no significant difference between groups (p = 0.7). Conclusion: We conclude that neither postoperative imbalance nor the type of fusion in patients undergoing ACDF for degenerative pathology showed a positive correlation with the development of cervical radiographic ASD over an average follow-up of 8 years.

ID: 772

RF106: Does position of pedicle screws correlate with adjacent segment degeneration? An average 6-year follow-up retrospective study

Valentino Latallade ¹ , Matias Pereira Duarte ² , Ivan Huespe ¹ , Gonzalo Kido ¹ , Matias Petracchi ¹ , Marcelo Gruenberg ¹

¹ Hospital Italiano de Buenos Aires, CABA, Argentina,

² Clinica la Pequeña Familia, Junin, Argentina

Introduction: Adjacent segment degeneration (ASD) is still a frequent consequence in medium- and long-term follow-up after lumbar fusions. Several variables have been identified as risk factors for ASD development after lumbar fusion, however, the evidence discussing the relevance of pedicle screw (PS) position within the first instrumented vertebral (FIV) remains scarce. The primary objective was to assess the correlation between pedicle screw (PS) position of the first instrumented vertebra (FIV) with proximal ASD development or progression. Secondarily, we aimed to establish cut-off points of the analyzed variables that may determine a security zone for the PS position. Material and Methods: Patients ≥ 55 years who have undergone lumbar fusion with a minimum 2-year follow-up were included. Radiographic PS position was assessed by the angle between the 1st PS and the upper vertebral endplate (VE) and by the PS tip-VE distance. Radiographic parameters of ASD included: disc height, disc angle, and vertebral listhesis. ASD magnetic resonance imaging (MRI) parameters included: disc degeneration and lumbar stenosis. ROC curve analysis was performed to identify the best cut-off points in correlation with lumbar stenosis. Results: Forty-eight patients were included with an average follow-up of 6 years. PS tip-VE distance and PS-VE angle were both positively correlated with: 1) Delta (Δ) lumbar stenosis; 2) Δ Disc degeneration; and 3) Δ Disc height. ROC curve analysis correlating PS tip-VE distance and PS-VE angle with an increase in the canal stenosis severity ≥2 degrees resulted in a cut-off point of 36% and 9.5°, respectively. Conclusion: The cranial orientation (PS-VE angle) of the pedicle screw in the first instrumented vertebra, along with a shorter pedicle screw tip-vertebral endplate distance (PS tip-VE), positively correlated with ASD progression at an average 6-year follow-up. Protective values against lumbar stenosis were identified as a PS tip-VE distance ≥ 36% of the first instrumented vertebra height and a PS-VE angle ≤ 9.5° relative to the upper vertebral endplate.

RF07: SPINAL ONCOLOGY 1

ID: 451

RF107: Neuro-osseous growth mismatch identified on MRI is associated with later curve progression in adolescent idiopathic scoliosis

Peter Udby ¹ , Cyrus Zamany ^1,2 , Sidsel Fruergaard ¹ , Nicolai Kaltoft ³ , Martin Gehrchen ¹ , Benny Dahl ¹ , Søren Ohrt-Nissen ¹

¹ Rigshospitalet, Department of Orthopedic Surgery, Spine Unit, Copenhagen, Denmark,

² Zealand University Hospital, Department of Orthopedic Surgery, Koege, Denmark,

³ Rigshospitalet, Department of Radiology, Copenhagen, Denmark

Introduction: Adolescent idiopathic scoliosis (AIS) is a complex 3-dimensional deformity of the spine with a prevalence of 2-3% of the general population. Some types of AIS progress to a severe deformity that may result in low back pain, impaired physical function, psychological symptoms, and cosmetic concerns. The underlying etiology of AIS has been extensively studied and the identification of patients at risk of progressive scoliosis is paramount to guide treatment at the early stage. This aim of this study was to investigate the relationship between spinal cord anatomy and the risk of curve progression in mild to moderate AIS. Material and Methods: Over a six-year period, we prospectively included patients presenting with AIS. Irrespective of curve severity, patients underwent full-spine MRIs. Patients were followed until skeletal maturity or surgery and categorized as progressive or non-progressive. We included patients with curves < 40° on presentation, with MRI scans available for 3-D reconstruction. We measured the true lateral cord space (LCS) ratio, a measure of the lateral displacement of the medulla in the spinal canal. Curve progression was defined as a Cobb angle increase ≥ 10° at follow-up. Results: Of the 64 included patients, 18 (28%) progressed more than 10 degrees during follow-up. At baseline, mean age in the progression and non-progression group was 13.1 ± 1.6 vs. 15.8 ± 1.5 years (p < 0.001), and mean Cobb angle was 32° ± 7 vs. 26° ± 9 (p < 0.001). The time from baseline x-ray to MRI was 1.3 ± 3 months vs. 1.7 ± 3.6 months (p = 0.738). LCS ratio was 1.5 (IQR: 1.1-1.7) in the progression group and 1.0 (IQR:0.8-1.3) in the non-progression group (p < 0.001). When matched for baseline Cobb angle and age, median LCS ratio was 1.5 [1.1, 1.7] and 0.9 [0.7-1.2] in the progression and non-progression group, respectively (p < 0.001). Conclusion: We found significant displacement of the medulla towards the concavity of the curve in progressive AIS cases. This supports the theory of a neuro-osseous growth mismatch as a part of the etiopathophysiology of AIS and may play a predictive role in the prognosis of milder cases of AIS.

ID: 1561

RF108: Spinal osteotomies are a risk factor for motor evoked potential changes during spine deformity surgery

Dejan Čeleš ¹ , Janez Mohar ^1,2 , Robert Cirman ¹ , Zoran Rodi ^{1 2}

¹ Orthopaedic Hospital Valdoltra, Ankaran, Slovenia,

² Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia

Introduction: Aim of this study was to determine the rate of motor evoked potential (MEP) alerts and the associated risk of postoperative motor deficits during thoracic and lumbar spine deformity surgeries. Material and Methods: A consecutive series of 88 patients underwent 99 spine surgeries from 2016 to 2024. MEP alerts were based on an amplitude loss exceeding 75% without recovery after increasing stimulation by up to 100V. The timing of the MEP alert was recorded at specific surgical stages: pedicle screw placement (PSP), correction maneuver (CORR), or osteotomy (OST). Postoperative day 1 (POD1) lower extremity motor scores were assessed. Results: MEP alerts were recorded in 27 surgeries (27%, N = 27/99), with 26% (7/27) of patients experiencing a POD1 motor deficit. Most alerts (48%, 13/27) occurred during OST (30%, 13/39), followed by PSP (8/90) and CORR (6/87) (p = 0.0001). In response, interventions were performed in all 27 surgeries, including a surgical pause, optimization of arterial pressure and oxygenation, and, as needed, rod removal, less aggressive correction, or further decompression. Following these interventions, MEPs fully improved in 15 surgeries (56%), partially improved in 9 (33%), and showed no improvement in 3 (11%). Among patients with full or partial MEP recovery, 0% and 44% (N = 4/9) respectively, experienced a POD1 motor deficit. In contrast, 100% (3/3) of patients without MEP improvement had a POD1 motor deficit (p = 0.0002). Of the 7 patients with a POD1 deficit, 6 had an MEP alert during OST (15.4%, 6/39) and 1 during CORR (1.1%, 1/87). Conclusion: Spinal osteotomies are associated with the highest rate of MEP alerts and the highest risk of POD1 motor deficits. Full or partial recovery of MEPs following intraoperative intervention significantly reduced the risk of POD1 deficits, with absolute risk reductions of 100% and 56%, respectively. All patients without MEP improvement exhibited a POD1 neurologic deficit.

ID: 648

RF109: Long-term quality-of-life, functional and detailed neurological outcome after IONM-aided microsurgical resection of cervical and thoracic intramedullary spinal cord tumors - a prospective cohort study

Sebastian Siller ^1,2 , Sylvain Duell ² , Deniz Reyhaniye ² , Stefan Zausinger ^2,3 , Joerg-Christian Tonn ² , Andrea Szelenyi ²

¹ University Hospital Regensburg, Department of Neurosurgery, Regensburg, Germany,

² LMU Hospital, Department of Neurosurgery, Munich, Germany,

³ Wirbelsaeulentherapie am Rindermarkt, Department of Neurosurgery, Munich, Germany

Introduction: IONM-aided microsurgical resection is the therapy of choice for cervical and thoracic intramedullary spinal cord tumors (IMSCTs). While coarse neurological outcome has been multiply reported, more detailed long-term outcome for quality-of-life (QoL) aspects and functional/detailed neurological status have been reported rarely. Material and Methods: We prospectively assessed 40 patients (m/f: 26/14, median age: 47 years) undergoing cervical/thoracic IMSCT surgery with intraoperative recording of muscular motor and somatosensory evoked potentials, Direct Wave and free-running electromyography. Detailed neurological status, McCormick Score, as well as QoL with regard to Physical/Mental Compound Short-Form-36 Health Survey Score (SF-36-P/MCS) and Barthel-Index (BI) were assessed pre- and immediately postoperatively as well as at during long-term follow-up (mean 29 months) and correlated with patients’/tumor characteristics. Results: 78% of the tumors were located in the cervical and 22% in the thoracic spine. Preoperativeley, motor deficits were present in 40%, sensory disturbances in 78% and gait ataxia in 38% of the patients; median McCormick Score was 1, mean SF-36-P/MCS 45.1/43.3 and median BI 100 in the overall cohort. Gross-total resection was accomplished in 88%. At last follow-up, 80% of the patients had a postoperative improvement or stable course in motor function, 25% in sensory function and 75% in gait function compared to the preoperative status; the overall cohort’s median McCormick Score was 1, mean SF-36-P-/MCS 44.5/44.5 and median BI 100 with no significant differences compared to the preoperative status for each item. Rates for individual improvement/stability/deterioration in QoL aspects were 30%/33%/37% for SF36-PCS, 33%/35%/32% for SF-36-MCS. Presence of a permanent postoperatively new or worsened sensory deficit after surgery (OR = 0.01, p = 0.022) and a preoperatively higher score in SF36-PCS (OR = 0.77; p = 0.016) were significant risk factors for a worse long-term outcome regarding the physical component of QoL perception. Conclusion: QoL aspects improve or stabilize in more than 60% of the patients during long-term follow-up after microsurgical resection of cervicothoracic IMSCTs. Persistence of a postoperative deterioration in sensory function and a higher preoperative QoL perception are significant predictors for a worse QoL long-term outcome regarding the physical component of QoL perception.

ID: 604

RF110: Ephiteliod hemangioma of the spine: a case series and treatment flow chart - Experience of a single centre

Emanuela Asunis ¹ , Chiara Cini ¹ , Cristiana Griffoni ¹ , Stefano Bandiera ¹ , Alberto Righi ² , Riccardo Ghermandi ¹ , Valerio Pipola ¹ , Marco Girolami ¹ , Giuseppe Tedesco ¹ , Marco Gambarotti ¹ , Alessandro Gasbarrini ³

¹ IRCCS Istituto Ortopedico Rizzoli, Chirurgia Vertebrale, Bologna, Italy,

² IRCCS Istituto Ortopedico Rizzoli, Anatomia Patologica, Bologna, Italy,

³ Rizzoli, Bologna, Italy

Introduction: Epithelioid Hemangioma is recognized by the World Health Organization as a distinct benign neoplasm; however, it is characterized by locally aggressive and rarely metastasizing behavior. Very few cases of EH of spine have been reported in the literature; therefore, it is difficult to make evidence-based therapeutic decisions for these patients. We report herein our experience with eleven patients suffering from EH of the spine. Materials and Methods: In this case series the patients were identified from the Pathological Anatomy Register of the Rizzoli Orthopedic Institute from 2016 to present. The surgical, clinical and radiographic data were retrospectively analyzed. Pathology records were accurately examined. Results: The ten patients included two men and eight women. Patients aged between 15 and 75 years (with average age of 45.7 years). All patients presented had lytic vertebral body lesion, six of them with pathological fracture. The majority of patients (80%) presented myelo-radicular compression. Other long bone localizations were detected in 3 patients. All patients were surgically treated and preoperative embolization were performed in all cases. In six patients an intralesional resection was performed. Of these, three patients received gross total resection (GTR) and three Subtotal Resection STR. Only one patient was treated in an emergency setting with posterior element decompression and fixation for pathological fracture with unknown nature. After pathologist’s result positive for EH, the patient underwent adjuvant conventional RT. After six months, a new surgery was required. The follow-up available for all the patients ranged from 6 to 85 months (average 33 months). One patients who underwent en bloc resection suffered FOR wound dehiscence and required a surgical revision 11 days after surgery. The same patient, had mechanical complication with loss of correction at the 18^th month of follow up and then a revision surgery and extension with sacropelvic fixation. Conclusions: In light of the literature review and the clinical experience of our center, we can consider eh a locally aggressive tumor that requires surgical treatment in case of symptoms. In this regard, we propose a treatment algorithm that could be useful in the management of patients with this rare disease because of the absence of guidelines to this time.

ID: 1991

RF111: Intramedullary astrocytomas: therapeutic management and impact on survival and functional state

Aziz Bedioui ¹ , Wièm Mansour ¹ , Ghassen Gader ¹ , Kerima Belhajali ¹ , Skander Guediche ¹ , Mohamed Zouaghi ¹ , Mouna Rkhami ¹ , Mohamed Badri ¹ , Kamel Bahri ¹ , Ihsen Zammel ¹

¹ Trauma and Burns Center of Ben Arous, Neurosurgery, Ben Arous, Tunisia

Introduction: Intramedullary astrocytomas (IMAs) are rare tumors, that occurs mainly among young individuals. They can be the cause of severe handicap. Clinical manifestations are not specific and they are those of a progressive spinal cord compression. Spine MRI is essential for diagnosis and follow up. Given their infiltrating nature and the usual absence of a dissection plane with adjacent spinal cord, IMAs represent a difficult therapeutical challenge, specifically in their surgical treatment. Consequently, this puts both the functional and vital prognosis at stake. However, advancement in microsurgery, ultrasonic cavitation, sonography and neuro-monitoring largely improved the outcome of surgery. Radiotherapy represents another relevant element in the treatment arsenal of IMAs. Material and Methods: We made a retrospective study about 21 patients treated for IMAs in a 9-years period. These patients were treated in two different neurosurgery departments in Tunis, Tunisia, with collaboration with two different radiotherapy department. The delay of follow-up was 2 years after surgery. Results: The patients mean age was 36,1 years. There was a discreet male predominance (sex ratio of 1.1). The predominant symptoms were motor deficit (76%) and sphincter dysfunction (57%), followed by back pain, sensory disorders and spine deformations. Before surgery, 67% of patients presented a good functional state, according to McCormick scale (grade I and II). MRI allowed diagnosis in all cases. Tumor limits were blurry in 86% of patients. The more frequent location was the thoracic spine (57%). Spine deformation and spine static disorders were found in 4 patients (19%). Gross total resection was obtained in 7 patients (33%), while partial resection was done in 14 patients (67%). Six patients (29%) had complementary spine fusion. 38% of patients presented an immediate postoperative functional deterioration, with only 48% of patients presenting a good functional state. However, at 2-years follow-up, most of the patients presented an improvement of their functional state, with 68% of patients having a grade I or II on McCormick scale. Pathology found WHO grade I tumors in 19% of patients, grade II in 67% and grade III in 14% of patients. Seven patients (33%) received adjuvant radiotherapy. Overall survival 2-years after surgery was at 90%, while progress free survival was at 57%. Conclusion: In our study we found that gross total resection is associated to better oncological results, with a progress free survival of 71%, even though it is related to more immediate postoperative functional deterioration (43%). Additionally, we noted that after a partial resection, complementary radiotherapy improved progress free survival: 57% vs 29% in patients having not received radiotherapy, but with less satisfying functional results (33% of improvement vs 50%).

ID: 2575

RF112: Carbon fiber implant for spinal tumors: outcomes and complications

Lancelot Benn ¹ , Oliver Tannous ^2,3 , Andrew Mo ³ , Addisu Mesfin ⁴

¹ Medstar Orthopaedic Institute, Washington Hospital Center, Washington, United States,

² Medstar Orthopaedic Institute, Georgetown School of Medicine, Washington, United States,

³ Medstar Orthopaedic Institute, Georgetown School of Medicine, Washington, United States,

⁴ Medstar Orthopaedic Institute, Georgetown School of Medicine, Orthopaedics, Washington, United States

Introduction: Due to advances in the detection and treatment of cancer, life expectancy for cancer patients has increased. There is a shift towards less invasive approaches for metastatic spine disease. Carbon fiber implants provide better post-op visualization for radiation therapy planning and for obtaining imaging for surveillance purposes. Materials/Methods: A retrospective series of spinal tumor patients managed from 12/2020 - 03/2024. Inclusion criteria were patients with primary or metastatic spine tumors undergoing a carbon fiber instrumentation. Patient demographics (age, sex, race/ethnicity) as well as tumor histology, levels of surgery, type of implants used (open pedicle screw, percutaneous pedicle screws) and hybrid constructs (combination of titanium screws and rods with carbon fiber implants) and number of screws. Intraoperative, post-op surgical/implant complications, length of follow-up, and patient survival were collected. Results: 26 patients undergoing 27 procedures (14 percutaneous and 13 open) with 133 carbon fiber screws and one carbon fiber corpectomy cage met the inclusion criteria. The demographics were: average age 61.2 years (15-83), 11 Females, 15 Males, 18 Whites, 6 Blacks, 2 Hispanics. Tumor types were Multiple Myeloma (4), Colon cancer (4), Breast (4), Thyroid (2), Prostate (2), Lung (2), Pancreatic (2), (1), Squamous Cell (1), Aneurysmal bone cyst [ABC] (2), Endometrial (1), Hepatocellular (1), and Esophageal (1). Tumor locations were Thoracic (n = 10), Lumbar (n = 13), and Sacral (n = 3). The average estimated blood loss (EBL) was 486.9 ml (50-2000), with the percutaneous implant group having significantly less blood loss compared to the open group (442.5 ml vs. 534.6 ml, p < 0.05). Most patients (N = 20) had a carbon fiber-only construct, and 6 had a hybrid construct where carbon fiber rods or cages were combined with titanium implants. There were 0 intra-op complications. Post-op one patient with carbon fiber-only implants underwent revision surgery within 2 weeks of surgery to reposition a right S1 symptomatic percutaneous screw. All three patients that were treated for sacral tumors developed surgical site infection post-op that required incision and drainage. Nine patients had passed away at the latest follow-up, and 17 patients were alive with a follow-up spanning 1 to 32 months (average of 8.3 months). Conclusion: Carbon fiber implants for spinal tumors appear to be equivalent to titanium implants, with one implant-related complication requiring a revision. Multi-center studies are needed to evaluate the long-term effectiveness of these implants and to justify the high cost of these implants.

ID: 2401

RF113: Towards defining frailty in the metastatic spine population: an observational study from the Metastatic Tumor Research and Outcome Network (MTRON)

Raphaële Charest-Morin ¹ , Michael Weber ² , John Shin ³ , Alessandro Luzzati ⁴ , Alexander Disch ⁵ , Alessandro Gasbarrini ⁶ , Jorrit-Jan Verlaan ⁷ , William Teixeira ⁸ , Arjun Sahgal ⁹ , Ilya Laufer ¹⁰ , Áron Lazáry ¹¹ , Dean Chou ¹² , Charles Fisher ¹³ , Ziya Gokaslan ¹⁴ , Michael Fehlings ¹⁵ , Laurence Rhines ¹⁶ , Addisu Mesfin ¹⁷ , Chetan Bettegowda ¹⁸ , Daniel Sciubba ¹⁹ , Tony Goldschlager ²⁰ , Cordula Netzer ²¹ , Michelle Clarke ²² , John O'Toole ²³ , Stefano Boriani ²⁴ , Ori Barzilai ²⁵ , Norio Kawahara ²⁶ , Naresh Kumar ²⁷ , Nicolas Dea ¹ , Jeremy Reynolds ²⁸ , C. Rory Goodwin ²⁹

¹ Vancouver General Hospital, University of British Columbia, Orthopaedic Surgery, Vancouver, Canada,

² McGill University, Montreal, Canada,

³ Penn Medicine, Philadelphia, United States,

⁴ IRCCS Istituto Ortopedico Galeazzi, Milan, Italy,

⁵ University Hospital Carl Gustav Carus, Dresden, Germany,

⁶ Rizzoli Institute, Bologna, Italy,

⁷ UMC Utrecht, Utrecht, Netherlands,

⁸ Instituto do Câncer do Estado de São Paulo, Sao Paulo, Brazil,

⁹ Sunnybrook Health Sciences Center, Toronto, Canada,

¹⁰ NYU Langone, New York, United States,

¹¹ National Center for Spinal Disorders, Budapest, Hungary,

¹² Columbia University Irving Medical Center, New York, United States,

¹³ University of British Columbia , Vancouver, Canada,

¹⁴ Brown University, Warren Alpert School of Medicine, Providence, United States,

¹⁵ University of Toronto, Toronto, Canada,

¹⁶ MD Anderson Cancer Centre, Houston, United States,

¹⁷ Medstar Orthopaedic Institute, Georgetown University School of Medicine, Washington, United States,

¹⁸ Johns Hopkins University School of Medicine, Baltimore, United States,

¹⁹ Northwell Health, Manhasset, United States,

²⁰ Monash University, Melbourne, Australia,

²¹ University of Basel, Basel, Switzerland,

²² Mayo Clinic, Department of Neurologic Surgery, Rochester, United States,

²³ Rush University Medical Center, Chicago, United States,

²⁴ University of Bologna, Bologna, Italy,

²⁵ Memorial Sloan Kettering, New York, Canada,

²⁶ Kanazawa Medical University, Uchinada, Ishikawa, Japan,

²⁷ National University Hospital, Singapore, Singapore,

²⁸ Oxford University, Oxford, United Kingdom,

²⁹ Duke, Durham, United States

Introduction: Frailty has been associated with poor outcomes, including increased mortality, adverse events, and longer hospital stays in the general spine population. Current frailty tools have shown poor performance in the metastatic spine disease (MSD) population. Determining the ability to tolerate a surgical procedure in this population is complex and needs to factor in not only patient variables but also oncological variables. The primary objective was to determine the patient and oncologic predictors associated with 90-days mortality in patients undergoing surgical treatment for MSD. The secondary objectives were to determine the patient and oncologic predictors associated with non-home discharge and worsening of the ECOG performance status at the 3 months postoperative visit. This study was conducted on the behalf of the AO Spine Knowledge Forum Tumor. Material and Methods: Patients treated surgically for MSD who were enrolled prospectively between Q3/2017 and Q3/2024 in the multicentric Metastatic Tumor Research and Outcome Network (MTRON) study were analyzed retrospectively. The following procedure was repeated 100 times. 1) The full data set was divided between a training and a testing set (80% vs 20%). 2) The Lasso algorithm was repeated 100 times to perform variable selection with 80% of the training set used for training and the rest for validation. 3) The variables selected at least 80% of the time were used with multiple logistic regression models on the test set. The variables selected are those included by the procedure at least 80% of the time. To provide an estimate of odds ratio, a Firth logistic regression was performed on the full data set. These analyses were conducted for the primary and secondary objectives. Results: A total of 1267 patients were included. Variable selection: The best model to predict 90-days mortality was the weighted logistic regression model (Mean AUC 0.72 over 100 repetitions). Variables predicting 90-days mortality were number of comorbidities, body-mass index (BMI), baseline ECOG performance status, the total number of metastatic site, the presence of visceral/brain metastasis, the primary tumor site histology, the degree of epidural disease and having received prior treatment for the metastasis prior. Odds Ratio. On logistic regression for the 90-day mortality; having an ECOG score 0-1 at baseline decreased the odds (OR 0.54, 95% CI 0.37-0.79), each comorbidity increased the odds 24 % (OR 1.24, 95% CI 1.10-1.40), elevated BMI has a slight positive effect (OR 0.94, 95%CI 0.90-0.97), the presence of brain/visceral metastasis and presence of > 5 bone metastasis at other sites increased the odds by twofold (OR 2.17, 95%CI 1.48-3.19 and OR 2.31, 95%CI 1.57-3.42, respectively), having received prior treatment for the metastasis prior decreased the odds (OR 0.44, 95%CI 0.30-0,63) and not having a prostate or breast cancer primary tumor site increased the odds (OR 2.50, 95%CI 1.20-5.09 to OR 2.21, 95%CI 1.41-3.57 depending on the histology). Conclusion: This study highlights the multidimensional aspect of frailty in the MSD population. We have isolated patients, and oncological variables that are predictive of 90 days mortality, non-home discharge and worsening performance status.

ID: 1743

RF114: Rapid custom spinal bracing for pain management in multiple myeloma patients

Anna Courtney ¹ , Sam Walmsley ¹ , Jack Choong ¹ , Connor Mumford ¹ , Jason Bernard ² , Tim Bishop ² , Darren Lui ²

¹ The London Orthotic Consultancy, Kingston Upon Thames, United Kingdom,

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

Introduction: This study examines the effectiveness of rapid custom spinal braces in managing pain, stabilising fractures, and improving the quality of life in multiple myeloma patients. Standard bracing and stock braces often fall short due to the unique anatomical challenges these patients present with. Our research explores custom-made spinal braces designed with advanced 3D scanning technology, enabling a rapid turnaround and personalised fit. Material and Methods: Patients were assessed and fitted (within a 48-hour production window) using 3D scanning technology to create custom braces. A retrospective qualitative study was conducted with 85 patients, of whom 54 provided us with complete responses. The study evaluated the impact of these braces on pain management and patient satisfaction. Pain levels were measured using the Visual Analogue Scale (VAS) before, during, and after brace use, and the rate of surgical interventions, such as kyphoplasty, was recorded. Results: The study showed a significant reduction in pain, with VAS scores dropping from 6.2 pre-bracing to 3.5 during brace use, and a further drop to 2.8 after brace removal (p = 0.0003). The post-bracing kyphoplasty rate was 9.3%, suggesting a potential reduction in the need for surgical interventions. Patient satisfaction was high, with an average score of 8/10. All patients reported use of the brace for 8-16 hours daily, with a usage mean of 12 hours. Self-reported feedback indicates that rapid custom spinal braces led to improved independence in completing daily activities in this patient group, and high overall satisfaction with the brace. Conclusion: Rapid custom spinal bracing may be an effective adjunct for assisting with pain and potentially reducing surgical intervention rates in multiple myeloma patients. The integration of 3D scanning technology into clinical practice enhances the speed and precision of brace fitting, significantly improving patient comfort and outcomes. Future improvements could involve hospital staff using a widely accessible iPhone app for scanning, which would further enhance timely brace provision, and warrants further investigation, as does the implication of pain medication throughout treatment.

ID: 1794

RF115: The METASTRA project: computer-aided effective fracture risk stratification of patients with vertebral metastases for personalised treatment through robust computational models validated in clinical settings

Luca Cristofolini ¹ , Giovanni Barbanti Bròdano ² , Vincenzo Carbone ³ , Enrico Dall'Ara ⁴ , Rudolf Ferenc ⁵ , Stephen Ferguson ⁶ , Jose Manuel García-Aznar ⁷ , Niccole Germscheid ⁸ , Áron Lazáry ⁹ , Nikolina Lednicki ¹⁰ , Marco Palanca ¹ , Sanja Sale ¹¹ , Peter Vajkoczy ¹² , Jorrit-Jan Verlaan ¹³ , Lazslo Vidacs ¹⁴ , Emmanuelle Voisin ¹⁵

¹ University of Bologna, Bologna, Italy,

² IRCCS Rizzoli Orthopaedic Institute, Bologna, Italy,

³ InSilicoTrials Technologies SpA, Trieste, Italy,

⁴ University of Sheffield, Sheffield, United Kingdom,

⁵ FRONTENDART SZOFTVER KFT, Szeged, Hungary,

⁶ ETH Zurich, Zurich, Switzerland,

⁷ University of Zaragoza, Zaragoza, Spain,

⁸ AO Foundation, Davos, Switzerland,

⁹ BHC Budapest, Budapest, Hungary,

¹⁰ Rice to Research and Innovation Services-RISE d.o.o., Zagreb, Croatia,

¹¹ EURICE, Ingbert, Germany,

¹² Charite, Berlin, Germany,

¹³ UMC Utrecht, Utrecht, Netherlands,

¹⁴ University of Szeged, Szeged, Hungary,

¹⁵ VCLS, Boulogne-Billancourt, France

Introduction: Patients with positive cancer prognosis frequently develop metastases. In 30-70% subjects, metastases affect the spine. The strength of the affected vertebrae is significantly compromised. Vertebral fractures occur in ≈30% patients. The dilemma is whether to operate to stabilize the spine (often exposing patients to unnecessary surgeries) or leave the patient exposed to a fracture risk (with dramatic consequences). The standard-of-care are scoring systems (e.g. Spine Instability Neoplastic Score, SINS) based on medical images, with little consideration of the spine biomechanics, and of the structure of the vertebrae involved. Such scoring systems fail to provide clear indications in ≈60% patients. This often results in under- or over-treatment. Material and Methods: METASTRA is a project developed by biomechanicians, modelers, clinicians, experts in verification, validation, uncertainty quantification and certification from 15 partners across Europe. METASTRA will improve the stratification of patients with vertebral metastases evaluating their risk of fracture by developing dedicated reliable computational models based on Explainable Artificial Intelligence (AI) and on personalized Physiology-based biomechanical (VPH) models. The METASTRA-AI model is expected to be able to stratify most of the cases, while requiring very limited effort end cost, based on a semi-automated analysis of the medical files and images. The cases which are not reliably stratified through the AI model, are examined through a more detailed and personalized biomechanical VPH model. To build credibility of the models, they must be trained on large datasets. The model predictions must be validated against reliable data. METASTRA is developing three unprecedentedly large datasets: a multicentric retrospective study of 2000 patients (providing medical files and images to train the models), a multicentric prospective study of 200 patients (where the METASTRA models will be tested), and an ex-vivo dataset where 120 specimens from metastatic donors are tested from the organ-level down to the sub-tissue level. Results: The METASTRA project has been running for little more than 1 year (total duration: 5 years). The results so far are extremely encouraging. The retrospective study is nearly completed. This has already allowed building and successfully running the first instance of the METASTRA-AI models. The experimental testing of the metastatic vertebrae is already 30% completed, with multimodal clinical images, mechanical properties (strain distribution, failure load) being collected. The sub-models of the personalized biomechanical model (METASTRA-VPH) are showing excellent agreement with the experimental data. Conclusion: The METASTRA approach is expected to cut down the indeterminate diagnoses from the current 60% down to 20% of cases. This will provide better life quality and more realistic expectations, to the patients. METASTRA will also reduce the overall workload for clinicians. While each patient assessed with the METASTRA tools will cost between 200 and 1000 €, the METASTRA approach is estimated to save € 1.4B/year from avoiding unnecessary surgeries, and € 1.0B/year from prevented fractures.

Acknowledgements: METASTRA project funded by the European Union, HEU topic HLTH-2022-12-01, grant 101080135

ID: 2852

RF116: Metastatic spinal cord compression secondary to genitourinary primary cancers: a retrospective study

Yasemin Keith ¹ , Priyanshu Saha ¹ , Charles Taylor ¹ , Zion Hwang ¹ , Adnan Sheikh ¹ , Hasan Raza ¹ , Liam Rose ¹ , Timothy Bishop ¹ , Jason Bernard ¹ , Darren Lui ¹

¹ St George's University Hospitals NHS Foundation Trust, Department of Orthopedic and Spinal Surgery, London, United Kingdom

Introduction: Genitourinary cancers have significant global burden. Earlier disease may be suitable for tumour removal; however, advanced disease may involve more radical surgery, and/or other systemic/targeted treatments. One possible complication of genitourinary cancer is metastatic spinal cord compression (MSCC). This paper therefore aims to assess how various factors affect clinical outcomes in MSCC from genitourinary cancers. Materials and Methods: This retrospective study included 23 patients with MSCC from genitourinary primary cancers, identified from an MDT database from 2017 to 2023 (2,503 total MSCC cases). Cases of bladder, penile, and testicular cancer were included. There were no cases of ureteric or urethral cancer. Prostate cancer and renal cancer were excluded. Data collected included age, sex, primary tumour type, survival time, and 30-day mortality. ECOG performance score, Frankel scores, Charlson Comorbidity Index scores and Tokuhashi scores were calculated. Surgical versus non-surgical treatment outcomes were compared. Results: Among the 23 patients, 19 were male (82.6%) and 4 were female (17.4%). 4 underwent surgery (17.4%), and 19 (82.6%) did not. The mean age was 73 years, ranging from 41-92 years. Average age of surgical patients was 66, compared to 75 for non-surgical patients. Surgical patients also had better ECOG performance scores and Frankel scores at presentation. Average survival was 26 months in patients aged between 40-49, compared to 0 months for those aged 90-99. Those scoring 0 on the Charlson comorbidity score had average survival of 5.92 months, compared those scoring 2 (6.33 months), and 3 (0 months). Bladder cancer was the most common primary cancer (82.6%). The longest survival time was seen in penile cancer (13.5 months), compared to 5.67 months for bladder, and 0 months for testicular. Mean survival time was 1.67 months for surgical patients, and 7.13 months for non-surgical patients. 30-day mortality rates were 0% for surgical patients and 31.6% for non-surgical patients. All patients except one scored between 0-8 on the Tokuhashi score and had an average survival time of 6.52 months. The remaining patient scored between 9-11 and survived for one month. Conclusion: Survival time was greater in younger patients. Penile cancer cases had longer survival compared to bladder and testicular. Variation in survival times was also seen by Charlson comorbidity score, however lacking clear correlation. Findings may have been limited by the low prevalence of genitourinary MSCC in this cohort, particularly in certain sub-groups. On average, surgical patients were younger, with better ECOG performance scores and Frankel scores at presentation. While surgical patients showed shorter overall survival times, they demonstrated a lower 30-day mortality rate, and more research is needed to explore this. There was an unexpected contradiction between actual and predicted outcomes from the Tokuhashi score – those scoring higher had shorter survival time, contrasting what is predicted. This potentially calls into question the use of the Tokuhashi scoring system in genitourinary MSCC.

ID: 1869

RF117: Management of pathological vertebral fractures: indications for device-assisted kyphoplasty in spinal metastasis and systematic review

Esteban Ramirez Ferrer ¹ , Romulo Andrade de Almeida ¹ , Rob North ¹ , Christopher Alvarez-Breckenridge ¹ , Laurence Rhines ¹ , Claudio Tatsui ¹

¹ MD Anderson Cancer Center, Neurosurgery, Houston, United States

Background: Vertebroplasty has traditionally been used to achieve symptomatic relief for painful osteoporotic vertebral fractures. Its role in the management of pathological fractures is emerging, with reports of device-assisted Spinejack Kyphoplasty (SJK) demonstrating improvement in vertebral height and postoperative pain control. However, no specific indications exist for using these devices in the context of pathological vertebral fractures. Also, the role of SJK has not been compared to conventional Vertebral Augmentation Techniques (VAT), such as Balloon-Assisted Kyphoplasty (BK), in this context. Methods: We conducted a single institution retrospective review from January 2019 to January 2023 of patients with spinal metastases who underwent kyphoplasty with SJK and collected information regarding perioperative pain, radiographic features, and complication rates. Additionally, we performed a systematic review under PRISMA guidelines using Medline, Web of Science, and Google Scholar databases, comparing spinal metastasis patients with indications for percutaneous vertebral height augmentation using SJK and compared to patients who underwent regular vertebroplasty or BKP. Outcomes regarding pain scores (Visual Analogue Scale, VAS), vertebral height gain (VHG), and kyphotic angle (KA) were assessed. Results: 17 patients were collected with 42 devices implanted, 21 levels treated, and a female rate of 47.1%. Clear Cell Renal Cell Carcinoma (CCRCC) was the most common primary tumor diagnosis. Thoracolumbar junction was the most common level treated. An absolute VAS reduction of 2 points between the preoperative and early postoperative period was documented. All the patients had a preoperative SINS equal to or greater than 7. The mean height gain was 3.88mm during the immediate postoperative period, 2.01mm at 6 months, and 1.62 mm at 12 months. Statistically significant vertebral height increase was documented (p < 0.01). Regarding the systematic review, 623 articles were found with the search strategy. Eleven articles were included, and a total of 602 patients were analyzed. There were 123 patients in the SJK group and 479 in the BKP group. No differences were found regarding demographic features. Postoperative pain VAS at 6 months was lower in the SJK group (p < 0.01). Conclusion: SJK is a reliable approach for pathologic fractures secondary to neoplastic infiltration with comparable results to BKP. The integrity of pedicles and posterior wall, loss of 30-70% of height, and the presence of trabecular bone are reliable indications for SJK in Spinal Metastatic Disease. A high Spinal Neoplastic Instability (SINS) alone should not be considered an independent variable for SJK contraindication. Nevertheless, longer follow-up is required to assess long-term outcomes regarding pain and radiographic results.

ID: 1124

RF118: The OxMINT pathway. A novel service for the rapid referral assessment and treatment of metastatic spinal patients in Oxford. The design and implementation of the patient pathway and the multidisciplinary team meeting and comparison with other international models

Georgios Zilidis ¹ , Clare Jacobs ² , Gerard Mawhinney ³ , Jeremy Reynolds ⁴ , Yaron Berkowitz ⁵ , Emma Kenney-Herbert ⁶ , Ather Siddiqi ⁷ , James Teh ⁸ , Basavaraj Chari ⁸ , Martin Gillies ⁹ , Tim Mccormick ¹⁰ , Ami Sabharwal ¹¹ , Stana Bojanic ¹² , Hayley Jones ¹¹ , Alex Anderson ¹³ , Claire Worrall ¹³ , Niamh Louwman ¹³ , Harriet Dent ¹³ , Mariam Latif ¹⁴ , Tomasz Bajorek ¹⁵ , Victoria Bradley ¹⁶ , Nicolas Beresford-Cleary ¹⁷

¹ Oxford University Hospitals, Spinal Surgery , OxMINT, Oxford, United Kingdom,

² Churchill Hospital, Oxford University Hospitals, Department of Clinical Oncology, OxMINT, Oxford, United Kingdom,

³ Oxford University Hospitals, Oxford Spinal Surgery Unit, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom,

⁴ Oxford University Hospitals, Spinal Surgery, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom,

⁵ Oxford University Hospitals, Radiology Department, Nuffield Orthopaedic Centre, Experimental Medicine Division, Nuffield Department of Experimental Medicine, University of Oxford, Oxford, United Kingdom,

⁶ Oxford University Hospitals , Department of Clinical Oncology, Oxford, United Kingdom,

⁷ Oxford University Hospitals, Orthopaedic Oncology and Arthroplasty, Oxford, United Kingdom,

⁸ Oxford University Hospitals, Department of Musculoskeletal Radiology, Oxford, United Kingdom,

⁹ Oxford Functional Neurosurgery University of Oxford, Oxford, United Kingdom,

¹⁰ Oxford University Hospitals, Department of Anaesthesia, Oxford, United Kingdom,

¹¹ Oxford University Hospitals, Department of Clinical Oncology, Churchill Hospital, Oxford, United Kingdom,

¹² Oxford University Hospitals , Department of Neurosurgery, Oxford, United Kingdom,

¹³ Oxford University Hospitals, Department of Palliative Medicine, Oxford, United Kingdom,

¹⁴ Oxford University Hospitals, Department of Anaesthetics, Oxford, United Kingdom,

¹⁵ Oxford University Hospitals, Department of Psychiatry, Oxford, United Kingdom,

¹⁶ Oxford University Hospitals, Department of Palliative Medicine, OxMINT, Oxford, United Kingdom,

¹⁷ Oxford University Hospitals, Oxford Spinal Surgery Unit, OxMINT, Oxford, United Kingdom

Introduction: Metastatic or secondary bone tumours are known to be associated with skeletal-related events, such as pathological fractures, spinal cord compression, or hypercalcemia. These deposits are often highly painful and cause significant functional impairment and harm to quality of life. Recent advances in cancer treatment have improved patient survival in almost all cancer types which amplifies the magnitude of the problems as more patients are living longer with greater volumes of symptomatic bony disease. We would estimate based on rising prevalence of cancer in the UK predicted to reach 3.5million in 2025, the number of patients living with bone metastases will reach epidemic proportions. While management pathways of the much rarer primary bone tumours are well established there has not until now there has not been a unified pathway for the review of secondary bone tumour patients in the UK to ensure equitable and appropriate management. Materials and Methods: We will describe the published literature describing service models internationally that offer comprehensive or semi-comprehensive e services for managing symptomatic bone metastases. We will then offer a critique of how they meet the patient need. Results: We will describe the setup of a best-in-class novel collaborative multi-specialty service to assess and treat all patients with symptomatic metastatic bone disease in Oxfordshire, England. This will include description of the change process of engaging relevant specialties, accessing funding streams to support protected workforce and creation of novel patient pathways. Conclusion: Integrated and collaborative models for working are essential for the successful management of metastatic bone disease and this provides an example of service design and set up.

ID: 1454

RF119: Treatment of acute neurological deficit in patients with spinal metastasis with unknown primary - A 12-year retrospective review

Samir Dalvie ¹ , Rohan Parihar ¹ , Kshitij Chaudhary ¹

¹ P.D. Hinduja Hospital and MRC, Spine Surgery, Mumbai, India

Introduction: Patients presenting with metastatic epidural spinal cord compression (MESCC) with acute neurological deficit require emergency spinal cord decompression. The treatment recommendations for MESCC differ for patients with known metastasis versus those presenting with unknown primary. Surgery is preferred for solid organ metastasis with known diagnosis while radiotherapy is the preferred treatment option for hematolymphoid malignancies. However, this decision cannot be made for patients presenting to the ER without prior diagnosis of the primary. Material and Methods: Retrospectively reviewed a single hospital database of patients with spinal metastasis with unknown primary with neurological deficit who underwent surgery on an emergency basis between January 2009 to December 2021. Cases with known histology of tumor were excluded. Results: 18 patients underwent urgent posterior surgical decompression ± stabilization for unknown MESCC + neurological deficit. Postoperative histological diagnoses were multiple myeloma in 6 (33.3%), lymphoma 3 (16.6%), prostate 3 (16.6%), Lung 2 (11.1%), and Thyroid 2 (11.1%). The thoracic spine was the most common site (15, 83%). Preoperative neurological deficit was Frankel A (5), B (1), C (8), and D (3). Nine patients (50%) with hematolymphoid malignancy presented with Frankel A (2), B (1), C (4), and D (2). The spine instability neoplastic score (SINS) for the hematolymphoid malignancies were classified as stable in 1, indeterminate in 4 and unstable in 4. Conclusion: 50% of patients presenting with a neurological deficit of unknown MESC had a hematolymphoid diagnosis out of which 4 (44%) patients had an unstable spine. Current international guidelines recommend primary radiation for these malignancies + deficit without frank instability. However, in ER where the diagnosis is not known quickly enough, surgery is offered despite the knowledge that about 50% of cases are ultra-radiosensitive. At present, there is no reliable way to establish a histopathological diagnosis in the emergency setting.

ID: 2172

RF120: The outcomes of radiotherapy with or without surgery in patients with solitary plasmocitoma of the spine: a sistematic review and meta-analysis

Jackson Daniel ¹ , Luis Eduardo Carelli Texeira da Silva ² , Denise Silva ³ , Jose Alberto Oliveira ⁴

¹ University Hospital of Federal University of Piaui, Neurosurgery, Teresina, Brazil,

² National Institute of Traumatology and Orthopedics, Rio de Janeiro, Brazil,

³ Estadual University of Piaui, Teresina, Brazil,

⁴ Federal University of Ceara, Fortaleza, Brazil

Introduction: The treatment of solitary plasmacytoma of the spine poses a clinical challenge, with therapeutic options including isolated radiotherapy and radiotherapy combined with surgery. While both approaches aim to control disease progression and improve patients' quality of life, there is a growing need to understand their respective efficacy and safety profiles. Solitary plasmacytoma of bone (SPB) has potential to progress to multiple myeloma (MM), then, the decision between surgical or non-surgical interventions, such as radiotherapy alone, remains controversial, especially regarding progression to MM and long-term survival. This meta-analysis aims to evaluate the impact of these interventions in patients with SPB of the spine. Methods: Searches were conducted in PubMed, Cochrane and Embase databases up to September 2024, using combinations of the following terms and their variations: “spine plasmacytoma”, “surgery” and “Radiotherapy”. The search followed the PRISMA guidelines to ensure transparency and reproducibility and resulted in 642 studies, 36 were selected for full reading. Data collection form was created using the Cochrane Consumers and Communication Review Group Data Extraction model and statistical analysis was performed using a random-effects model to adjust for heterogeneity among the included studies. Results: A total of 36 studies with a total of 9838 patients were included in this meta-analysis, involving patients with solitary bone plasmacytoma (SBP) of the spine treated with surgery and/or radiotherapy. Progression to multiple myeloma (MM) was 45,97%, significantly higher in patients who received surgery combined with radiotherapy compared with patients who received isolated radiotherapy or other non-surgical treatments, whose progression was 19.41% (p < 0.05). The 5-year survival was similar between the groups with and without surgery (68.06% vs. 69.17%, respectively), with no statistical difference (p > 0.05). Follow-up identified a higher progression rate (46.0%) to MM in patients with long-term follow-up (≥ 60 months) compared with short-term follow-up (< 60 months), whose progression was 19.3% (p < 0.05). Comparison between SPB and extramedullary plasmacytoma (EMP) showed a higher rate of progression to MM in patients with SPB (49.4%) compared EMP (17.75%). Meta-regression found no significant association between age and progression to MM or survival (p > 0.05). Heterogeneity between studies was moderate, with I² = 51.87% for progression to MM and I² = 35.72% for survival. Conclusion: This meta-analysis demonstrates that patients with solitary bone plasmacytoma (SBP) treated with surgery combined with radiotherapy have a higher rate of progression to multiple myeloma (MM), while 5-year survival rate is comparable between both therapies. Although age was not a significant predictor of progression to MM or survival, the moderate heterogeneity between studies suggests that further research is needed to understand the variables that influence these outcomes. Future investigations should consider the impact of clinical factors, such as patients’ baseline condition and follow-up time, to refine treatment strategies and optimize long-term outcomes.

ID: 1440

RF121: 3-dimensional morphometric study of sacral variability and dysmorphism for use in planning iliosacral stabilization surgery

Vikram Murugan ¹ , Karthik Tappa ² , Bryce Lanier ³ , Jestin Williams ² , Shalin Patel ² , Laurence Rhines ² , Justin Bird ²

¹ Creighton University School of Medicine, Omaha, United States,

² MD Anderson Cancer Center, Houston, United States,

³ Howard University, Washington, DC, United States

Introduction: Iliosacral instrumentation is widely performed to address destabilizing injuries of the spinopelvic junction. The safe and effective placement of devices into the sacrum depends on the dimensions and integrity of the sacral bony corridor. Pathologic fractures of the sacrum uniquely disrupt its structural integrity and create significant challenges. Historically, pathologic sacral fractures have been treated either non-operatively or with lumbopelvic stabilization, iliosacral screws ± PMMA augmentation, or (more recently) photodynamic nails. The safety and efficacy of placing devices into the sacrum hinges on the “S1 and S2 Bony Corridors,” critical anatomic pathways constrained by both bony and neurologic structures. Morphologic variability and dysmorphic characteristics such as L5-S1 sacralization, tongue-in-groove phenomenon, and mammillary bodies may pose significant challenges to these fixation techniques, driving the need for individualized surgical planning. A 3-dimensional morphometric analysis was performed to provide insights into sacral morphology for the purpose of planning iliosacral stabilization procedures in the context of pathologic sacral fractures. Material and Methods: High-resolution computed tomography pelvic datasets from 46 patients were analyzed using 3D Slicer. Three-dimensional interlandmark distances were measured. The cohort was categorized by age, sex, normal sacral morphology, and various dysmorphic sacral forms. Patients with prior pelvic conditions, history of pelvic surgeries, or reported congenital abnormalities were excluded. Results: Twenty-two cases (47.8%) exhibited sacral dysmorphism, including 11/24 males and 11/22 females. There were 10 cases of lumbar-sacral fusion/articulation, 7 cases with mammillary processes, and 5 cases exhibiting the tongue-in-groove phenomenon. The average S1 anterior bony corridor heights were 17.45 millimeters in the non-dysmorphic male sacra and 14.65 millimeters for non-dysmorphic female sacra, contrasting sharply with 11.80 millimeters for dysmorphic cases. Dysmorphic groups showed additional variance: L5-S1 dysmorphia had S1 corridor heights of 14.23 mm, tongue-in-groove cases had heights of 9.68 mm, and cases with mammillary processes showed heights of 7.45 mm. S1-S2 interforamen distance also varied, with normal averages at 13.94 mm, L5-S1 at 12.63 mm, tongue-in-groove at 16.01 mm, and mammillary processes at 15.02 mm. S1 foraminal canals length averaged 17.08 mm in normal male sacra compared to 16.03 mm in dysmorphic male sacra and 15.18 mm in normal female sacra compared to 13.54 mm dysmorphic female sacra. Conclusion: Significant anatomical variability exists between sexes and among those with sacral dysmorphism. Reduced S1 anterior bony corridor heights in dysmorphic cases, along with significant differences in foramen widths between sexes, further support the necessity for tailored approaches to ensure safe and effective implant placement. Future research should aim to refine these morphometric insights, develop biomechanical models, and incorporate them into surgical planning tools to improve the safety and efficacy of spinopelvic stabilization surgery.

ID: 1463

RF122: The OxMINT metastatic spine tumour checklist

Georgios Zilidis ¹ , Clare Jacobs ² , Gerard Mawhinney ³ , Jeremy Reynolds ³ , Yaron Berkowitz ⁴ , Emma Kenney-Herbert ² , Ather Siddiqi ⁵ , James Teh ⁴ , Basavaraj Chari ⁴ , Martin Gillies ⁶ , Tim Mccormick ⁷ , Ami Sabharwal ² , Stana Bojanic ⁶ , Hayley Jones ² , Alex Anderson ⁸ , Claire Worrall ⁸ , Niamh Louwman ⁸ , Harriet Dent ⁸ , Mariam Latif ⁷ , Tomasz Bajorek ⁹ , Victoria Bradley ⁸ , Nicolas Beresford-Cleary ¹

¹ Oxford University Hospitals, Oxford Spinal Surgery Unit, OxMINT, Oxford, United Kingdom,

² Oxford University Hospitals, Department of Clinical Oncology, Churchill Hospital, Oxford, United Kingdom,

³ Oxford University Hospitals , Oxford Spinal Surgery Unit, Oxford, United Kingdom,

⁴ Oxford University Hospitals, Department of Musculoskeletal Radiology, Oxford, United Kingdom,

⁵ Oxford University Hospitals, Orthopaedic Oncology and Arthroplasty, Oxford, United Kingdom,

⁶ Oxford University Hospitals, Department of Neurosurgery, Oxford, United Kingdom,

⁷ Oxford University Hospitals, Department of Anaesthesiology, Oxford, United Kingdom,

⁸ Oxford University Hospitals, Department of Palliative Medicine, Oxford, United Kingdom,

⁹ Oxford University Hospitals , Department of Psychiatry, Oxford, United Kingdom

Introduction: With an ever-increasing prevalence of cancer in the population metastatic spine tumours are becoming far more common than previously. With recent advances in oncological, surgical and radiological treatment options most doctors including spinal surgeons, oncologists and radiologists are having difficulty identifying the best treatment options for each individual patient. Methods: We analysed the literature and created a checklist which will help both doctors who need to refer a patient with metastatic spine disease to a specialist service as well as specialists like spinal surgeons, oncologists and radiologists who will be asked to offer a specialist opinion on the information that they will need to collect in order to make the best possible personalised treatment recommendations. Results: The minimum dataset for each metastatic spinal patient should include: the patient identification details, age, sex, details on the primary oncological diagnosis and how long ago it was made, previous and current oncological surgical treatments including previous radiotherapy with details on the exact timing and dose used, information on previous radiofrequency ablations, the location and extent of metastatic disease in other organs from recent CT chest abdomen pelvis and PET scans and with systemic oncological treatment options are still available. Furthermore it should include the patient’s current performance status, Karnofsky performance score, spinal instability neoplastic score, Tokuhashi Score and prognosis from the treating oncologist. It should also include information on the patient’s visual analogue pain score, the Patient Expectations in Spine Oncology (PEPSO) questioner and the Spine Oncology Study Group Outcome Questionnaire. Conclusion: The Oxford metastatic spine tumour (OMST) checklist is a useful tool for both the referring and receiving doctor in order to collect all the relevant data that are necessary to make the best possible decision for each individual patient with metastatic spine disease. It can be used during the multidisciplinary team meeting (tumour board) in order to ensure that all relevant data have been collected. It can also be used during follow-up appointments in clinic to monitor the outcomes of metastatic spinal disease patients after treatment.

ID: 2043

RF123: Designing and implementing a complex spine multidisciplinary team (MDT) approach to recognising and treating oligometastatic spinal disease: a quaternary level 1 spine unit experience

Priyanshu Saha ¹ , Charles Taylor ¹ , Zion Hwang ¹ , Adnan Sheikh ¹ , James Geddes ¹ , Liam Rose ¹ , Hasan Raza ¹ , Jason Bernard ¹ , Timothy Bishop ¹ , Darren Lui ¹

¹ St George's University Hospitals NHS Foundation Trust, Department of Orthopedic and Spinal Surgery, London, United Kingdom

Introduction: Treatment paradigms for spinal oligometastatic disease (OMD) and oligo-progressive disease (OPD) have evolved. Oncological radical treatment can lead to disease free state in patients. Traditionally this was achieved with Tomita En Bloc spondylectomy. Stereotactic ablative radiotherapy (SABR) as a primary treatment modality can deliver radical treatment without open surgery. In separation surgery, postoperative SABR can be indicated in metachronous OMD for Maximum Local Control (MLC). Other novel methods include radiofrequency ablation (RFA) which can be combined with the techniques described above. Traditionally, surgery is indicated for neurological deficit and pain. Goals of surgery was maintenance of ambulation and continence. Indications of surgery should also include oncological control regardless of neurological deficit or pain because radical treatment can improve prognosis. The authors present a quaternary level 1 spinal center’s experience in managing spinal oligometastatic disease. Material and Methods: A retrospective review of spinal OMD management at a quaternary level 1 spinal center between 2017 and 2024. Demographic data, type of tumour, surgical type (En Bloc, Separation Surgery (SS), RFA, Palliative Decompression (PD), cases with local recurrence and mortality data were examined. Statistical analysis was done using GraphPad Prism. Results: 166 patients were identified with OMD or OPD. Synchronous – 15%, Metachronous – 85%. Mean age: 56 (13-84); females: 55% males: 45, histological: Renal – 24%, Breast – 17%, Sarcoma – 12%, Prostate – 7%, Colorectal – 7%, Lung – 8%, Ovarian – 2%, Chordoma – 5%, Thyroid – 5%, Plasmacytoma – 3%, Paraganglioma – 2%, Bladder – 2%, Melanoma – 2%, Lymphoma – 2%, Schwannoma – 2%, Neuroendocrine – 2%. 103 radical surgical patients, 66.5% had separation surgery, 8.5% had En Bloc Surgery, RFA ± Cement was 18%, 16 patients also had undergone RFA and cement for enhanced MLC and infection control. Mortality: 1 year mortality for radical surgery is 1.5% and 0% for separation surgery + SABR. Including palliative surgery: 30-day mortality – 6% (n = 4; 2 COVID, 1 encephalopathy, 1 T1RF), none of the deceased patients had post adjuvant radiotherapy and no hardware related issues. 2 patients had PD.1 year mortality – 9% (n = 6, 2 additional patients: patient 5: SS converted to PD as no SABR was administered; patient 6: PD) Infection: 30-day infection rate – 1.5%, 1 yr infection rate 3%. Local Recurrence (LR): 1-year: 0%, 2-year: 1.5% 3-year: 3% Conclusion: It is important to recognise OMD and OPD states which allowed consideration of oncological radical treatment. Our data shows excellent 7-year local recurrence rates of 3% and 1 year infection rate of 3%. Failure to deliver radical treatment in OMD shows higher 1 year mortality compared to palliative treatment (1.5% versus 7.5%). To provide Enneking Appropriate treatment for OMD or OPD there are various surgical techniques in the armamentarium including En Bloc Surgery, separation surgery and RFA. For carefully selected patients, non-surgical methods can also be indicated such as primary treatment modality such as SABR.

ID: 2103

RF124: Survival prediction and management strategies for metastatic spinal cord compression in different tumour types: a retrospective analysis of surgical and non-surgical patients

Priyanshu Saha ¹ , Charles Taylor ¹ , Zion Hwang ¹ , Adnan Sheikh ¹ , Liam Rose ¹ , James Geddes ¹ , Hasan Raza ¹ , Jason Bernard ¹ , Timothy Bishop ¹ , Darren Lui ¹

¹ St George's University Hospitals NHS Foundation Trust, Department of Orthopedic and Spinal Surgery, London, United Kingdom

Introduction: Metastatic spinal cord compression (MSCC) is a severe complication of advanced cancer, resulting in significant morbidity and mortality. MSCC can lead to acute neurological deficits, pain, and reduced quality of life. This study aims to evaluate the effectiveness of the Tokuhashi scoring system in predicting survival outcomes and the clinical parameters influencing the decision between surgical and non-surgical management in MSCC patients across six primary cancer types: renal cell carcinoma (RCC), gastrointestinal (GI) cancers, gynaecological and genitourinary cancers, prostate cancer, breast cancer, and lung cancer. Material and Methods: This retrospective study analyzed data from 906 MSCC patients treated between 2017 and 2024. Data were collected from the iClip PowerChart system, including patient demographics, primary tumor location, symptoms at presentation, surgical details, ICU and hospital stay duration, Charlson Comorbidity Index (CCI) scores, Frankel scores, Tokuhashi scores, and survival outcomes. The study compared surgical and non-surgical patient groups across the different cancer subtypes. Results: Among the 69 RCC patients, surgical patients had a higher revised Tokuhashi score (mean 7.8) compared to non-surgical patients (mean 6.6), with a mean survival time of 8.33 months for surgical patients and 6.97 months for non-surgical patients. In the 154 GI cancer patients, surgical patients had a mean survival time of 6.35 months, compared to 5.15 months for non-surgical patients. Colorectal cancer was the most common primary tumor (54%). The audit of 138 gynaecological and genitourinary cancer patients revealed that surgical patients had higher Tokuhashi scores (mean 9.40) than non-surgical patients (mean 7.71). The 30-day mortality rate was 11.1% for surgical patients compared to 21.3% for non-surgical patients. Of the 398 prostate cancer patients with MSCC, 52 underwent surgery. Surgical patients had higher Tokuhashi scores and better survival outcomes, with a mean survival time of 10 months compared to 5.67 months for non-surgical patients. In 147 breast cancer patients, 39 underwent surgery. Higher CCI scores were associated with worse prognosis, while Tokuhashi scores varied from 5 to 14. Surgical patients showed improved Frankel scores post-treatment, indicating better neurological function. Among 131 lung cancer patients, 49 underwent surgery. The Tokuhashi score accurately predicted 58.8% of patients with expected survival < 6 months. Surgical patients had a mean survival time of 6.35 months compared to 5.15 months for non-surgical patients. Conclusion: The Tokuhashi scoring system demonstrates moderate accuracy in predicting survival outcomes for MSCC patients across various primary cancer types. Surgical intervention generally improves survival outcomes and neurological function, but the decision for surgery should consider additional factors such as comorbidity, patient age, and primary tumor type. This study underscores the need for a multidisciplinary approach and further research to refine prognostic tools and optimize management strategies for MSCC patients.

RF08: DEGENERATIVE CERVICAL SPINE SURGERY

ID: 1979

RF125: Comparative outcomes of laminectomy alone versus laminectomy with fusion in degenerative cervical myelopathy: a systematic review and meta-analysis

Christopher Lozano ^1,2,3 , Armaan Malhotra ^1,2,3 , Vishwathsen Karthikeyan ^1,2,3 , Husain Shakil ^1,2,3 , Jefferson Wilson ^1,2,3

¹ University of Toronto, Division of Neurosurgery, Toronto, Canada,

² University of Toronto, Institute of Health Policy, Management and Evaluation, Toronto, Canada,

³ St Michael's Hospital, Li Ka Shing Knowledge Institute, Toronto, Canada

Introduction: Degenerative Cervical Myelopathy (DCM) is a leading cause of spinal cord dysfunction and often requires surgical intervention to prevent neurological decline. Laminectomy, with or without fusion, is commonly performed in DCM patients. However, the impact of fusion on functional outcomes, the risk of post-laminectomy kyphosis, and complication rates remains unclear. This systematic review and meta-analysis (SRMA) aimed to compare these outcomes between laminectomy alone (LA) and laminectomy with fusion (LF). Material and Methods: Following PRISMA guidelines, we searched PubMed, MEDLINE, EMBASE, Scopus, and Web of Science for randomized controlled trials (RCTs) and observational cohort studies in adult DCM patients (age ≥ 18) undergoing LA or LF, with ≥ 12 months of follow-up. Primary outcomes were functional recovery (mJOA, JOA), incidence of post-laminectomy kyphosis, and complications. Random-effects meta-analysis models were used. Results: Twenty-five studies were included (1 RCT, 24 cohort studies), with 2,211 patients undergoing LA and 975 undergoing LF. There was variability in the outcome measures reported by these studies. Meta-analysis of four studies reporting mJOA scores showed no significant difference in functional improvement between LF and LA (mean difference = -0.40, 95% CI: -1.79 to 0.99, p = 0.573). The incidence of post-laminectomy kyphosis in LA patients ranged from 0% to 47%, with a pooled incidence rate of 2.02% per person-year (95% CI: 1.26% - 2.78%). Significant heterogeneity was present (I² = 84.59%, p < 0.0001), likely due to variations in follow-up duration and baseline alignment. Complications were significantly lower in LA compared to LF (OR = 0.4260, 95% CI: 0.2579 - 0.7037, p = 0.0092). A separate meta-analysis of 13 LA-only studies estimated a pooled complication rate of LA at 13.15% (95% CI: 11.38%-15.14%). Conclusion: Studies comparing LA versus LF for DCM demonstrate comparable functional outcomes based on the mJOA score. While LA is associated with a lower rate of short-term complications compared to LF, this benefit may come with a trade-off of an increased risk of post-laminectomy kyphosis, estimated at around 2% per person-year. Further studies are needed to understand the impact of delayed kyphosis on functional outcomes of LA patients with long term follow-up.

ID: 731

RF126: Feasibilty of posterior screw-rod fixation without bone graft in the treatment of unstable Hangman's frctures

Guangzhou Li ¹

¹ Department of Spine Surgery, Suining Central Hospital, Suining, China

Introduction: Previous study has showed that patients with unstable Hangman's fractures could be treated with posterior fixation without fusion, however, such study lacks comparison and the number of cases is small. The objective of this study was to evaluate the feasibility of posterior screw-rod fixation without bone graft in treating unstable Hangman's fractures, by comparing the efficacy of two surgical methods. Material and Methods: A retrospective analysis was conducted on 39 patients with unstable Hangman's fractures who underwent posterior screw-rod internal fixation at our hospital between 2014 and 2020, with a minimum follow-up of 2 years. There were 31 males and 8 females with an average age of 43.1 ± 16.1 years (range from 13 to 70 years). Patients were divided into two groups: Group A (22 patients) underwent posterior screw-rod fixation without bone graft, and Group B (17 patients) underwent posterior screw-rod fixation plus autogenous iliac bone graft fusion. The study compared operative time, blood loss, postoperative complications, and various efficacy assessment indices including visual analogue scale (VAS) scores, neck disability index (NDI), American Spinal Cord Injury Association (ASIA) spinal cord injury grade, Odom's grade, and radiographic parameters such as C2/3 displacement, angulation, and cervical lordosis. The operation time and blood loss, postoperative complications and postoperative curative effect evaluation indexes were recorded and compared between the two groups. The clinical outcomes were assessed using the Visual Analog Scale (VAS), the Neck Disability Index (NDI), and the Odom’s grading system. Plain radiography was used to measure the displacement and angulation of C2-C3, and cervical lordosis. Plain radiography and three-dimensional CT were also used to observe the bony fusions of fracture lines and the posterior facet joint and interbody fusion of C2-C3. Results: All the operations of 39 patients were completed successfully, and the average follow-up was 3.2 years. Group A demonstrated shorter operative times (99.3 ± 14.2 min vs. 137.9 ± 19.5 min), less blood loss (94.6 ± 12.6 ml vs. 140.6 ± 17.8 ml), and fewer operation-related complications compared to Group B (p < 0.05). Both groups showed significant improvements in VAS scores, NDI, and neurological function recovery, with no significant differences between groups at any follow-up time point. Postoperative C2/3 angulation, displacement, and cervical lordosis improved significantly in both groups, without significant intergroup differences. All patients achieved solid fracture fusion. In group A, spontaneous fusion at bilateral C2/3 facet joints was found in all patients, anterior bony bridge of intervertebral bodies at C2/3 in 1 case, posterior bony bridge of intervertebral bodies at C2/3 d in 9 cases, and spontaneous fusion of anterior and posterior edge of vertebral body in 4 cases. In group B, bony fusion of bilateral C2/3 facet joints was achieved in all the patients, no spontaneous fusion of the anterior edge of vertebral body, spontaneous fusion of the posterior edge of vertebral body occurred in 10 cases, and spontaneous fusion of both anterior and posterior edges of vertebral body occurred in 3 cases. At final follow-up, there was no statistical difference in the results of C2/3 facet joints and interbody fusion between the two groups (all facet joints were fused in both groups, and the interbody fusion rates in groups A and B were 63% and 76% , respectively) (p > 0.05). Conclusion: Posterior screw-rod fixation and fusion without or with bone graft can yielde satisfactory clinical outcomes in treating unstable Hangman's fractures. While both techniques achieved comparable fusion rates and functional improvements, posterior screw-rod fixation without bone graft can shorten the operative time, reduce intraoperative blood loss and avoid complications related to bone graft harvest. We carefully suggest that posterior screw-rod fixation without bone graft may represent a feasible and effective alternative for the surgical management of unstable Hangman's fractures.

Keywords: Hangman's fracture, posterior screw-rod fixation, bone graft, spontaneous fusion

ID: 2536

RF127: Defining developmental cervical spinal stenosis and its clinical implications using > 200- magnetic resonance images

Jason Cheung ¹ , Prudence Wing Hang Cheung ¹

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

Introduction: For degenerative cervical myelopathy (DCM), developmental cervical spinal stenosis (DcSS) is an important risk factor but its definition needs clarification. By specifically incorporating the multilevel characteristics of developmental spinal stenosis, this study aims to define DcSS using magnetic resonance imaging (MRI), to assess the prevalence of DcSS based on the defined values, and to evaluate whether the presence of DcSS predicts DCM. Material and Methods: This cross-sectional study analyzed MRI spine morphological parameters at C3 to C7 (including anteroposterior (AP) diameter of spinal canal, spinal cord and vertebral body) from a cohort of 95 DCM patients who underwent surgical decompression and 2019 individuals recruited from the general population. Level-specific median AP spinal canal diameter from DCM patients were used to screen for stenotic levels in the populated-based cohort. An individual with ≥ 3 vertebral levels (i.e. multilevel) of AP canal diameter smaller than the DCM median values was considered having DcSS. Receiver operating characteristic (ROC) analyses was used to determine the optimal cut-off canal diameter per level for DcSS. Multivariable logistic regression was performed for the prediction of developing DCM that warranted surgical intervention. Results: A total of 2114 individuals were studied, with mean age of 64.6 ± 11.9. Optimal cut-off AP spinal canal diameters for DcSS were: C3 < 12.9 mm, C4 < 11.8 mm, C5 < 11.9 mm, C6 < 12.3 mm, C7 < 13.3 mm. Based on these values, the prevalence rate of having DcSS at multilevel was 13.0% (262 of 2019) of the population-based cohort. Multilevel DcSS (OR 6.12, 95% CI, 3.97-9.42, p < 0.001) and gender (male, OR 4.06, 95% CI, 2.55-6.45, p < 0.001) were found predictors of developing DCM. Conclusion: Based on the MRI analyses of cervical spine morphologies of DCM patients and of the general population, this is the first study to define DcSS with level-specific cervical canal diameter cut-off values with the incorporation of the characteristics of multilevel involvement. Clinical use of these DcSS canal diameter cut-offs (C3 < 13 mm, C4 < 12 mm, C5 < 12 mm, C6 < 12.5 mm, C7 < 13.5 mm) aids in its diagnosis. Specifically, males with DcSS at ≥ 3 levels fulfilling those cut-offs are at high risk of developing DCM requiring surgery. These are useful parameters for close monitoring or for early intervention in patients with silent or early myelopathy.

ID: 2439

RF128: Results of surgical treatment of atlantoaxial instability and cranial settling in patients with rheumatoid arthritis: a series of 30 consecutive cases

François Dantas ¹ , Fernando Luiz Dantas ² , Antônio Carlos Vieira Caires ² , Bárbara Campos Mattos ² , Carlos Henrique De Figueiredo ² , Victor Kelles Tupy Da Fonseca ³

¹ Biocor Instituto/Rede D'Or, Neurocirurgie, Belo Horizonte, Brazil,

² Biocor Instituto/Rede D'Or, Neurosurgery, Belo Horizonte, Brazil,

³ Faculdade Ciências Médicas de Minas Gerais, Post-graduation, Belo Horizonte, Brazil

Introduction: Rheumatoid Arthritis (RA) is a systemic inflammatory disease of autoimmune nature and unknown etiology. RA is considered the most common inflammatory disease affecting the cervical spine. Involvement of the cervical spine is common, with a prevalence varying between 17% and 80%. Cervical disease in RA typically presents in one of three forms: atlantoaxial instability or subluxation, vertical axis instability or cranial settling, and subaxial subluxation. This study aims to demonstrate the effectiveness of atlantoaxial and craniocervical fusion in patients with cervical spine instability resulting from RA. Methods: A retrospective analysis was conducted on patients with RA who underwent surgery for atlantoaxial or craniocervical instability in a single institution, from January 2000 to January 2023. All patients were operated on by the same surgical team and had a minimum follow-up of 1 year. All patients underwent magnetic resonance imaging (MRI), computed tomography (CT) scan, and flexion and extension radiographs preoperatively. Age, sex, clinical status, type of surgery, complications, and clinical outcomes were evaluated. Patients were clinically classified on the Ranawat classification pre- and postoperatively (I no neurological deficit; II subjective weakness with hyperreflexia and dysesthesia; IIIa objective weakness, signs of myelopathy, ambulatory; and IIIb non-ambulatory, quadriparesis). Patients underwent atlantoaxial fusion in cases of atlantoaxial instability and occipitocervical fusion in cases of cranial settling or severe bony erosion of the C1 lateral masses. Decompression was performed in patients with severe spinal cord compression or myelopathy. All patients had follow-ups at 3 months, 6 months, and 1 year postoperatively. Radiographs were obtained in the immediate postoperative period and at 3 months, 6 months, and 1 year after surgery. MRI was performed at 6 months for patients in whom C1-C2 pannus was observed preoperatively, to assess pannus regression. Results: Thirty patients underwent surgery for craniocervical or atlantoaxial instability. Twenty-two were women and eight were men. Ages ranged from 36 to 84 years. Fifteen patients underwent atlantoaxial fusion (using the Magerl, Goel-Harms, or Wright techniques) and 15 underwent craniocervical fixation. Preoperatively, 3 patients had Ranawat grade I, 15 patients had grade II, 10 patients had grade IIIa and 2 had grade IIIb. There was pannus regression in all cases, and no hardware failures were observed. In patients who underwent atlantoaxial fusion, there was no progression of bone erosion or cranial settling at the final follow-up. There was neurological improvement in 90% of patients according to Ranawat's classification. Two postoperative complications were observed, one being a surgical wound infection and the other a transient neurological worsening. Conclusions: The craniocervical junction is commonly affected in RA. Craniocervical or atlantoaxial instability resulting from RA should be treated as early as possible, even in the absence of signs of spinal cord compression. Surgery is safe and effective and prevents disease progression in the craniocervical junction.

ID: 590

RF129: Effects of preoperative HbA1c on the rate of clinical improvement following anterior cervical discectomy and fusion

Noah Coleman ¹ , Ara Khoylyan ¹ , Matthew Parry ² , Alex Tang ² , Tan Chen ³

¹ Geisinger Commonwealth School of Medicine, Scranton, United States,

² Geisinger Health, Orthopaedic Surgery Northeast Residency, Wilkes-Barre, United States,

³ Geisinger Health, Department of Orthopaedic Surgery, Wilkes-Barre, United States

Introduction: Uncontrolled Diabetes Mellitus (DM) is associated with higher rates of post-operative complications following spinal surgery. There is limited data and consensus describing the long-term outcomes and clinical trajectory amongst post-operative diabetic patients following cervical spine surgery. The purpose of this study was to (1) compare post-operative patient-reported outcome measures (PROMs) between non-diabetic (non-DM) and diabetic (DM) patients undergoing Anterior Cervical Discectomy and Fusion (ADCF), and (2) characterize the clinical trajectory, complications, and rate of improvement between non-DM and DM cohorts. Material and Methods: Retrospective analysis was performed identifying non-DM and DM patients who underwent elective single or multi-level ACDFs for degenerative pathology between 2019-2023. Diabetes was defined as having a pre-operative HbA1c ≥ 6.5%. Patient demographics, Neck Disability Index (NDI) and Patient-Recorded Outcomes Measurement Information System (PROMIS) scores were collected longitudinally. Maximum medical improvement (MMI) as defined as the time point where more than 90% of the cohort achieves minimal clinically important difference (MCID) for both NDI and PROMIS score reports. Descriptive and inferential statistics were performed. Results: A total of 261 non-DM and 52 DM patients were included. The DM cohort was older (non-DM: 54.8 years, DM: 60.1 years, p < 0.001) and had higher BMI (non-DM: 30.3, DM: 35.4, p < 0.001). No difference was found for number of fusion levels (non-DM: 1.9, DM: 1.8, p = 0.360), postoperative complications (non-DM: 3%, DM: 8%, p = 0.109), and follow-up time (non-DM: 20.5 months, DM: 22.5 months, p = 0.464). Both cohorts had significant clinical improvement exceeding MCID at postoperative 1 year with no difference in ∆NDI (non-DM: 24.9; DM: 23.0; p = 0.824) or ∆PROMIS-Physical Function (non-DM: 7.1; DM: 9.1; p = 0.373). Clinical improvement was similar between single and multi-level fusions. MMI was achieved earlier amongst the non-DM cohort, with a significant difference in proportion of patients achieving MCID by 6 months (non-DM: 95%; DM: 84%; p = 0.010) and 1 year (non-DM: 97%; DM: 90%; p = 0.049). Multivariate analysis showed DM patients are less likely to achieve 1-year postoperative MCID based on PROMIS-Mental Function (OR: 0.176, p = 0.031) when controlling for age, BMI, sex, number of levels fused, and complications. Conclusion: Both diabetic and non-diabetic patients achieve similar long term clinical benefit following single and multi-level ACDF for degenerative pathology, with no difference in complication rates. Diabetic patients observe a comparatively slower rate to achieve maximum medical improvement. The results demonstrated emphasize the importance of counseling and setting postoperative expectations amongst higher risk surgical patients.

ID: 1497

RF130: Complication profiles leading to revision surgery after cervical disc arthroplasty

Giuseppe Loggia ¹ , Franziska Altorfer ¹ , Fedan Avrumova ¹ , Jiaqi Zhu ¹ , Celeste Abjornson ¹ , Darren Lebl ¹

¹ Hospital for Special Surgery, Spine, New York, United States

Introduction: Cervical disc arthroplasty (CDA) is a motion-preserving alternative to anterior cervical discectomy and fusion (ACDF) for cervical degenerative disc disease, however, complications such as migration, heterotopic ossification and osteolysis remain concerns. Data was collected from nine CDA devices which were included in the Food and Drug Administration (FDA) Manufacturer and User Facility Device Experience (MAUDE) database. This analysis evaluated early, intermediate, and late postoperative phases, as well as complications across the CDA devices. Additionally, CDA revisions due to conversion to fusion were summarized. Material and Methods: A retrospective analysis was performed using the MAUDE database, examining occurrences from January 2005 to September 2023 across nine FDA-approved CDA devices (Mobi-C, M6-C, Prodisc-C, Prestige, PCM, Bryan, Secure-C, Simplify, Discover). Complications were retrieved after the initial surgery and categorized by median onset time: early (< 6 months), intermediate (6-18 months), and late (> 18 months). These events were identified as reasons for revision surgery, as well as subsequent arthroplasty procedures or conversions to fusion. Results: A total of 707 revision cases were reviewed, with a median revision onset time of 12 months (IQR 3-36). Complication with a median early-onset time were led by implant migration (23.7%), with the PCM model accounting for 84.1% of these cases. Median intermediate-onset complications were primarily characterized by neck pain (15.4%), with the highest percentage observed in Simplify (23.8%). Subsidence (6.4%) was most common in the Prestige (14.8%) and Prodisc-C (12.4%) models. The most frequently seen late-onset complications had a median of 6.7% osteolysis (Simplify (19%) and M6-C (18.6%)), and 6.5% heterotopic ossification (Simplify (14.3%) and Prodisc (11.2%)). Eight out of the nine CDA models had a high percentage (> 69%) revision due to conversion to fusion, while Mobi-C demonstrated a lower value at 16.2%. Subsequently, 83.3% of Mobi-C revision cases were due to arthroplasty. Conclusion: Complications in CDA varied based on follow-up time and implant model. It is important to note, early concerns consisted of a high incidence of migration, particularly in the PCM model. Neck pain and subsidence were more commonly seen in the intermediate phase, while osteolysis and heterotopic ossification were noted in late-onset complications. Most CDA models were to converted to fusion during the revision surgery, except for the Mobi-C model, which predominantly underwent another arthroplasty.

ID: 743

RF131: Predictive factors of surgical adjacent segment disease in the cervical spine: a nested case-control study

Henri-Arthur Leroy ^1,2 , Pierre De Buck ³ , Tuong LU ¹ , Amélie Toubol ¹ , Boulos Ghannam ¹ , Pierre Haettel ¹ , Richard Assaker ^1,4

¹ CHU Lille, Department of Neurosurgery, Lille, France,

² AO Spine, Chairman for France, Davos, Switzerland,

³ Institut Catholique de Lille, Faculté de Médecine, Maïeutique, Sciences de la Santé, Lille, France,

⁴ AO Spine, Minimally Invasive Task Force, Davos, Switzerland

Study Design: Nested case-control study. Objective: During follow-up, radiological adjacent segment degeneration is reported in a significant proportion of patients operated on for ACDF. Only a part of them will experience clinical symptoms, ultimately requiring a second cervical spine surgery (_SASD). Our retrospective observational study, with prospective data collection, aims at considering the potential influence of cervical sagittal balance on post-ACDF second surgery based on postoperative imaging follow-up. Four key potential predictive factors were evaluated between cases and controls: the number of levels operated on, the local kyphosis, the C2-C7 sagittal vertical axis, and the postoperative cervical lordosis. Methods: Between January 1^st, 2014, to January 1^st, 2020, more than a thousand patients were operated for ACDF in the Spine Department of Lille University Hospital. From this population, we identified 19 cases and 76 matched controls. Cases were defined as follow: > 18 y/o, operated on for a second ACDF during the study period related to a sASD. Controls patients did not undergo a second cervical surgery during the study period. Each case was matched with 4 controls according to following criteria: age (± 10 years), sex (male, female), and duration of follow-up (± 6 months). Results: In our institution, the prevalence of sASD was of 1.76%. Neither the cervical sagittal axis (p = 0.12), nor the cervical lordosis (p = 0.40) were significantly related to sASD. However, we reported a strong tendency for the numbers of levels operated on and the postoperative local kyphosis to be risk factors of _SASD (respectively p = 0.056 and p = 0.06). Conclusion: On a large scale-based single center population, we did not report a clear impact of the cervical spine balance parameters such as cervical lordosis or cSVA on the risk of second cervical surgery at 2 years. Though, we highlighted the potential correlation between the initial number of cervical spine levels operated on and the occurrence of sASD and the presence of early local kyphosis.

ID: 509

RF132: Anterior cervical discectomy and fusion with polyetheretherketone cage or anterior cervical plate: a comparative evaluation of short-term outcomes

Vikramaditya Rai ¹ , Vipin Sharma ¹ , Mukesh Kumar ² , Lokesh Thakur ¹

¹ Dr. Rajendra Prasad Government Medical College, Department of Orthopaedics, Kangra, Himachal Pradesh, India,

² Dr. Rajendra Prasad Government Medical College, Department of Neurosurgery, Kangra, Himachal Pradesh, India

Introduction: Neck pain affects 30-50% of adults annually, with cervical degenerative disc disease (DDD) being a common cause. Anterior cervical discectomy and fusion (ACDF) is the gold standard treatment for cervical DDD when conservative methods fail. While anterior cervical plating has been traditionally used, it has potential drawbacks. Self-locking cage systems, particularly those made of polyetheretherketone (PEEK), have emerged as alternatives to address these concerns. Despite numerous studies, there is no consensus on the superiority of standalone cages versus plated ACDF constructs. This study aims to contribute to the existing literature by presenting a large single-institution case series comparing the outcomes of ACDF using standalone PEEK cages versus conventional ACDF with anterior cervical plating. By analyzing clinical and radiological results, we seek to provide insights into their relative efficacy and safety, informing surgical decision-making in cervical DDD treatment. Material and Methods: This ambidirectional cohort study, conducted from 2021 to 2023, included patients with degenerative cervical radiculopathy or radiculomyelopathy at C3-C4 to C6-C7 levels. Patients were randomized into two groups: ACDF with stand-alone PEEK cage (Group A) and conventional ACDF with anterior cervical plating (Group B). Surgeries used the Smith-Robinson technique, with slight variations between groups. Post-operative care included immobilization in a Philadelphia hard cervical collar for three months. Follow-ups were conducted at 1, 3, and 6 months post-surgery. Outcome measures included VAS scores, muscle power, NPDI, SWAL-Qol score, neck range of motion, handgrip strength, CSFS, Odom's criteria, arthrodesis, and cervical lordosis correction. Secondary outcomes included complications and fusion rates. Statistical analysis used appropriate tests for categorical and quantitative variables, with p < 0.05 considered significant. Results: Both groups showed significant improvements in pain and functional scores. At 6 months, mean VAS neck pain scores decreased to 0.53 ± 0.92 (plate) and 0.57 ± 0.94 (cage) (p = 0.912). Mean muscle power improved to 4.53 ± 0.92 (plate) and 4.64 ± 0.84 (cage) (p = 0.731). Median NPDI scores reduced to 18 (range 9-63) for plate and 18 (range 13-71) for cage groups (p > 0.05). Mean SWAL-QoL scores improved to 13.27 ± 6.35 (plate) and 13.29 ± 4.97 (cage) (p > 0.05). Normal neck flexion was achieved in 80% (plate) and 85.71% (cage) of patients (p > 0.05). Cobb's angle increased to 24.07° ± 2.05° (plate) and 24.29° ± 1.9° (cage) at 1 month (p = 0.768). Fusion rates at 6 months were 86.67% (plate) and 85.71% (cage) (p = 1.00). No implant malpositioning or subsidence was observed. At 6 months, 100% of patients in both groups reported no complications. Conclusion: At 6-month follow-up, ACDF with standalone PEEK cage and conventional ACDF with anterior cervical plating demonstrated equivalent effectiveness and safety in treating degenerative cervical spine conditions. Both techniques showed similar improvements in clinical outcomes, radiographic parameters, and fusion rates. The choice between the two methods can be guided by specific patient needs and surgeon preference.

ID: 2233

RF133: How reliable is the assessment of fusion status following ACDF using dynamic flexion-extension radiographs?

Christopher Martin ¹ , S. Tim Yoon ² , Ram Alluri ³ , Edward C. Benzel ⁴ , Christopher M. Bono ⁵ , Samuel Cho ⁶ , Jason Cheung ⁷ , Stipe Corluka ⁸ , Andreas Demetriades ⁹ , Zoher Ghogawala ¹⁰ , Robert Gunzburg ¹¹ , Waeel Hamouda ¹² , Amit Jain ¹³ , Hai Le ¹⁴ , Patrick Hsieh ³ , Philip Louie ¹⁵ , Hans-Jörg Meisel ¹⁶ , Sathish Muthu ¹⁷ , Gregory Schroeder ¹⁸ , Jeffrey C. Wang ³ , Yabin Wu ¹⁹

¹ University of Minnesota, Minneapolis, United States,

² Emory University, Atlanta, United States,

³ University of Southern California, Los Angeles, United States,

⁴ Cleveland Clinic Foundation, Cleveland, United States,

⁵ Massachusetts General Hospital, Department of Orthopaedic Surgery, Harvard Medical School, Boston, United States,

⁶ Ichan School of Medicine, New York, United States,

⁷ University of Hong Kong, Hong Kong, China,

⁸ University Hospital Centre Sestre Milosrdnice, Zagreb, Croatia,

⁹ Royal Infirmary Edinburgh, Edinburgh, United Kingdom,

¹⁰ Lahey Hospital and Medical Center, Burlington, United States,

¹¹ Edith Cavell Clinic, Brussels, Belgium,

¹² Cairo University, Cairo, Egypt,

¹³ Johns Hopkins University, Baltimore, United States,

¹⁴ University of California Davis, Davis, United States,

¹⁵ Virginia Mason Medical Center, Seattle, United States,

¹⁶ BG Klinikum Bergmannstrost , Halle, Germany,

¹⁷ Government Medical College, Tamil Nadu, India,

¹⁸ Rothman Institute and Thomas Jefferson University, Philadelphia, United States,

¹⁹ AO Foundation, Davos, Switzerland

Introduction: The radiographic diagnosis of non-union is not standardized. Prior authors have suggested using a cutoff of < 1 mm of interspinous process motion (ISPM) on flexion-extension radiographs, but the ability of practicing surgeons to make these measurements reliably is not clear. Methods: 29 practicing spine surgeons measured ISPM on 19 levels of ACDF from 9 patients. Surgeons relied on these measurements to report on the fusion status. Inter-observer correlation co-efficients (ICC), standard error (SEM) and the minimum detectable difference (MD) of these measurements were calculated. We screened for clerical errors by checking measurements more than one standard deviation from the group mean. Results: The ICC for ISPM was 0.77 (0.65; 0.88) with an SEM of 0.97 mm and an MD of 2.69mm. Agreement on fusion status was moderate, with an ICC of 0.6 (0.44; 0.76). After screening for and removing clerical errors, the ICC improved to 0.82 (0.71; 0.91), the SEM improved to 0.83 mm, and the MD improved to 2.29mm. Six reviewers had an ICC > 0.9. The ICC from these high performing reviewers was 0.94 (0.9; 0.97), the SEM was 0.45mm, and the MD was 1.26 mm. Conclusions: The MD of 2.29mm in our overall study group was not precise enough to support a cutoff of < 1 mm ISPM as the sole measurement technique in screening for non-union after ACDF, and there was only moderate agreement amongst surgeons on fusion status based on dynamic radiographs. More stringent techniques are necessary to avoid mis-diagnosing non-union in clinical studies. Future studies should consider auditing measurements to identify clerical errors.

ID: 2842

RF134: Clinical and radiological evaluation of non-treated intervertebral disc in multilevel ACDF

Giuseppe Barbagallo ¹ , Giacomo Cammarata ¹ , Massimiliano Maione ¹ , Francesco Certo ¹

¹ University Hospital “G. Rodolico - San Marco”, Neurosurgery, Catania, Italy

Introduction: Cervical degenerative pathology involving non-contiguous disc levels is a rare condition in which an intermediate disc segment remains unaffected despite degeneration of the adjacent cranial and caudal levels. In the context of surgical treatment with anterior cervical discectomy and fusion (ACDF), the necessity of fusing the intermediate segment, thereby sacrificing a healthy intervertebral disc, remains debated. This study aims to investigate the radiological progression of surgically untreated intermediate vertebral segments and their clinical correlates, compare the clinical and biomechanical outcomes of non-contiguous cervical fusion versus contiguous fusion of three cervical segments and assess the impact of different interbody devices on both intermediate and adjacent segments. Material and Methods: We conducted a retrospective analysis of 17 patients (11 males, 6 females) treated at the Neurosurgery Unit of the University-Hospital Policlinico “G. Rodolico-S. Marco,” Catania, Italy, between October 2004 and July 2021. The mean age was 51.29 years (range 37-66), and the average follow-up was 74.35 months (range 11-212). All patients were diagnosed with cervical disc degenerative disease with symptomatic radiculopathy and/or myelopathy unresponsive to conservative treatment and studied with cervical X-ray with dynamic tests, MRI and CT. Clinical assessment scales used: NDI, VAS, mJOA, and EMS. Preoperative and postoperative cervical parameters included Cervical Lordosis (CL), Cervical sagittal vertical axis (C2SVA), Neck Tilt (NT), T1 Slope (T1S), TIA, ROM of C2-C7, Intervertebral Disc height (DHI) and Cobb angle at the IS. Patients were divided into two groups: Group A (8 patients) underwent ACDF of two non-contiguous segments, and Group B (9 patients) underwent ACDF of three contiguous segments. Results: In Group A, the operated segments were C3-C4 and C5-C6 in 3 cases; C3-C4, C4-C5, and C6-C7 in 3 cases; C4-C5 and C6-C7 in 2 cases. In Group B, the segments were C3-C4, C4-C5, and C5-C6 in 4 cases; C4-C5, C5-C6, and C6-C7 in 5 cases. Postoperative mJOA and EMS scores at the last follow-up evaluation were higher in Group A compared to Group B (p-value < 0.05). VAS scores showed a greater reduction in Group A compared to Group B at the last follow-up. Post-operative NDI scores improved in both groups, with a non-significant trend favoring Group A. Globally, postoperative Neck Tilt and TIA values were higher than preoperative values, particularly in Group A, with a statistically significant difference compared to Group B (p-value = 0.05 and p-value < 0.04, respectively). No statistically significant differences were found between two groups regarding cervical lordosis, C2SVA, and T1 slope. The same applied to C2-C7 ROM values, although a greater preservation of ROM was confirmed in Group A. For the intermediate segment in Group A, DHI values were lower (p-value < 0.05) but with increased segmental ROM in the postoperative period. Conclusion: This study, characterized by a longer mean follow-up than previous reports, is the first to compare the outcomes of anterior cervical discectomy and fusion between non-contiguous and contiguous segments. The findings suggest that surgical treatment of two non-contiguous cervical segments is a safe and effective approach in the long term, preserving motion at the intermediate segment without accelerating disc degeneration.

ID: 1758

RF135: Porous titanium cages in anterior cervical discectomy: a retrospective multicenter study

Flavio Panico ¹ , Stefano Colonna ¹ , Ludovico Comite ¹ , Ayoub Saaid ¹ , Enrico Lobue ¹ , Andrea Gatto ¹ , Marco Ajello ¹ , Nicola Marengo ¹ , Alessandro Fiumefreddo ¹ , Salvatore Petrone ¹ , Nicola Zullo ² , Marco Bozzaro ³ , Diego Garbossa ¹ , Fabio Cofano ¹

¹ AOU Città della Salute e della Scienza Torino, Turin, Italy,

² Casa di Cura Città di Bra, Bra, Italy,

³ Humanitas Gradenigo, Turin, Italy

Introduction: ACDF stands as a widely employed surgical intervention for various cervical conditions. Commonly used interbody devices include allograft, titanium, and PEEK. In recent years, promising results are being obtained from trabecular titanium cages. Few data can be found in the literature regarding its efficacy in stand alone implants on the cervical segment. The purpose of this study is to evaluate the rates of subsidence, fusion, cage mobilization, maintenance of sagittal alignment in porous titanium cervical implants in absence of self-locking screws or plating for short segment fixation. Material and Methods: double-level ACDF for degenerative pathologies. Clinical outcomes and fusion rates were documented at 1, 6, and 12 months. VAS and SF-12 were used as outcome parameters. Radiographs and dynamic x-rays of the segment were performed at follow-up to assess rates of subsidence, fusion, cage mobilization, and segmental lordosis. Results: A total of 89 patients (102 levels) were evaluated. Effective improvement registered by NRS and SF-12 scores was achieved with statistical significance (p < 0.05). Effective fusion rate at 6 and 12 months was 84% and 96%, respectively. Radiological subsidence rate was 2.4% never causing the need for revision, with no cases of cage displacement despite the absence of self-locking screws or anterior plates. No significative differences were recorded among patients that underwent double-level fixations. Conclusion: Porous titanium cervical implants for anterior cervical fusion achieved significant clinical improvement after surgery, showing promising results in terms of subsidence and fusion rates, with negligible risk of displacement despite the absence of plates or self-locking screws for cage fixation.

ID: 1623

RF136: Recent global trends and hotspots in occipitocervical fusion: a bibliometric analysis and visualization study

Anna Gorbacheva ¹ , Clifford Pierre ¹ , Julius Gerstmeyer ¹ , Donald Davis ¹ , Bryan Anderson ¹ , Tara Heffernan ¹ , Luke Jouppi ¹ , Zeyad Daher ¹ , Arash Tabesh ¹ , Stephen Lockey ² , Amir Abdul-Jabbar ¹ , Rod Oskouian ¹ , Jens Chapman ¹

¹ Seattle Science Foundation, Seattle, United States,

² University of Virginia, Orthopaedic Surgery, Charlottesville, United States

Introduction: Occipitocervical arthrodesis has a variety of indications to treat craniocervical and atlantoaxial pathologies for which a selective cervical fusion would not provide sufficient stability. Over time, the indications for occipitocervical fusions (OCF) have evolved, as new technologies and surgical techniques were developed. In this bibliometric analysis, we aim to explore the progression of OCF literature over time, analyzing the trends in publications and citations, publishing countries and authors, keywords and topics. Material and Methods: The Web of Science (WoS) database was used for data retrieval on July 3^rd, 2024, with the search “occipitocervical fusion” OR “occipito-cervical fusion” OR “occipitocervical arthrodesis” OR “occipital cervical fusion” OR “occipital cervical arthrodesis” OR (“OCF” AND “spine surgery”). Excel was used to create the citation analysis and publication trend figures, along with the publishing countries and author analysis. The bibliometric software VosViewer was used to generate the keyword co-occurrence network visualizations. Results: Overall, 762 articles were extracted. The number of pertinent publications and citations increased until 2020 before beginning to decrease. We found that Ehlers Danlos syndrome (EDS) has become a more prevalent topic, as the association between EDS and craniocervical instability has received further scrutiny. “Dysphagia” continues to be a commonly cited topic, while, conversely, rheumatoid arthritis has decreased in publication frequency, possibly related to advances in medical management and surgical techniques. Overall, the United States of America, China, and Japan are the top publishing countries. Conclusion: This analysis of OCF literature provides a helpful overview of emerging trends and clinician concerns, especially as seen through the perspective of time.

ID: 2176

RF137: The impact of preoperative degree of cervical stenosis on postoperative outcomes after anterior cervical discectomy and fusion

Sahil Garg ¹ , Sean Muir ² , Alexa Dietrich ¹ , Sonny Gill ³

¹ Steadman Philippon Research Institute, Center for Outcomes Based Orthopaedic Research, Spine Research, Vail, United States,

² Ohio Health, Riverside Methodist Internal Medicine, Ohio, United States,

³ The Steadman Clinic, Spine Surgery, Vail, United States

Introduction: Anterior Cervical Discectomy and Fusion (ACDF) for degenerative cervical disease is an accepted treatment in patients with myelopathy. Cervical stenosis is described as the etiology of disease for patients with diagnosis of myelopathy. Symptomatic myelopathy may cause a significant amount of long-term disability for patients. The expected improvement in quality of life after ACDF has not been studied with respect to the degree of myelopathic disease experienced by patients. The purpose of this study is to determine if differences in improvement in patient reported outcomes after ACDF may associated with severity of preoperative cervical stenosis. Material and Methods: Retrospective chart review. 196 subjects who underwent an ACDF procedure with a diagnosis of cervical myelopathy were retrospectively identified at a single institution. 35 subjects met inclusion and exclusion criteria. Short-Form 12 (SF-12) data was analyzed for 35 subjects with a minimum of 1 year follow up. Subjects were categorized by their degree of preoperative central cervical stenosis using the Kang Scale. Differences in SF-12 scores, gender, and age were analyzed and compared between groups. Results: 35 subjects were included in the analysis. Using the Kang classification system, 3 subjects had mild stenosis, 19 subjects had moderate stenosis, and 13 subjects had severe stenosis. Subjects with moderate stenosis had a mean age at the time of surgery of 53.60 years with an average length of follow-up of 2.38 years. Subjects with severe stenosis had a mean age at the time of surgery of 53.50 years with an average length of follow-up of 2.60 years. Mean Total SF-12 scores in the moderate group were 88.93 preoperatively and 92.37 postoperatively. Mean follow-up time was 2.38 years. Mean SF-12 scores in the severe group were 82.95 preoperatively and 89.98 postoperatively. Mean follow-up time was 2.59 years. Conclusion: Subjects, regardless of degree of preoperative stenosis, observed improvement in their physical and mental status assessed through SF-12 at 1 year postoperatively. No significant differences in magnitude of improvement were observed between cohorts. Compared to those with mild stenosis, those with moderate and severe stenosis were likely to have higher baseline Mental Component SF-12 scores (p < 0.01). Further study is warranted using a larger study population and additional patient reported outcome measures (PROMs), such as NDI and PROMIS-10, to elucidate potential differences between groups.

ID: 1678

RF138: Establishing a diagnosis of degenerative cervical myelopathy in cases of diagnostic uncertainty using comprehensive clinical assessment: a prospective cohort study

Khadija Soufi ¹ , Omar Ortuno ¹ , Allan Martin ¹

¹ University of California, Davis, Neurological Surgery, Sacramento, United States

Introduction: Degenerative cervical myelopathy (DCM) is a common and debilitating condition due to cervical spinal cord compression and frequently occurs in patients with neurological, musculoskeletal, and other comorbidities which have overlapping symptoms with DCM that may obscure the diagnosis and confound measurement of severity. This study aimed to create a methodology to establish a diagnosis of DCM in patients with diagnostic uncertainty, including very mild symptoms and individuals with confounding comorbidities. Methods: A prospective cohort study was conducted with extensive data collection including medical/symptom history, QOL questionnaires, dynamometer and power testing in 22 myotomes, sensory testing, GRASSP-Myelopathy, and quantitative gait and balance testing using an electronic pressure mat. Patients with possible DCM were divided into two groups: definite DCM if the patient has ≥ 1 symptom, ≥1 clinical sign, imaging evidence of cervical cord compression, and no confounding comorbidities or diagnostic uncertainty (DU-DCM) group. Patients in the DU-DCM group were analyzed using comprehensive data where subjective and objective finding was independently considered by 3 raters. Patients were then assigned to the probable DCM group if they had one or more subjective and one or more objective findings attributed to DCM. Results: 104 age-matched healthy controls and 72 (47%) definite DCM (D-DCM), 50 (33%) probable DCM (P-DCM) and 31 (20%) improbable DCM (I-DCM) were enrolled. The rate of confounding comorbidities was 48% (24/50) P-DCM and 71% (22/31) I-DCM. Definite DCM compared to P-DCM and I-DCM had significantly worse symptoms history of arm weakness (D-DCM 3.3, P-DCM 2.8, I-DCM 1.2, p < 0.04), worse saddle numbness severity (p < 0.03), worse Jamar Hand Grip (D-DCM 1.5, P-DCM 1.9, I-DCM 1.8, p < 0.03), finger 2-3 pinch (D-DCM 1.3, P-DCM 1.6, I-DCM 1.6, p < 0.03), decreased mJOA upper extremity score (D-DCM 3.9, P-DCM 4.5, I-DCM 4.2, p < 0.05) and decreased monofilament hand scores (p < 0.04), along with more signs of hyper-reflexia in the biceps, triceps, brachioradialis and inverted brachioradialis (all p-values < 0.04). P-DCM compared to I-DCM had significantly decreased mJOA gait, hand coordination and total (p < 0.03) but not sensory or urinary incontinence scores, higher rates of hyper-reflexia (for biceps, triceps, brachioradialis, patella, p < 0.001), increased finger flexion weakness (p < 0.01), increased LE motor deficits (p < 0.001), decreased UE sensation to pin-prick and light touch (p < 0.001), decreased Jamar hand-grip strength (p < 0.001), decreased grasp dexterity completion (p < 0.02) and increased difficulty with berg balance overall score (and standing eyes closed, standing 1 leg, turning over shoulder) (p < 0.001) and impaired fast paced walk, Romberg and tandem stance (p < 0.01). Conclusion: Patients that present to a surgeon with suspected DCM frequently have comorbid conditions that complicate diagnosis. The use of a battery of clinical assessments appears to have pragmatic utility in categorizing a patient as probable or improbable DCM, although there is no diagnostic gold standard to compare this categorization against. Clinical signs such as hyperreflexia, Hoffman/Tromner/inverted brachioradialis reflexes, hand intrinsic weakness and incoordination, and gait ataxia are particularly useful to support a DCM diagnosis. Diagnostic criteria are needed that are sensitive to mild DCM, but allow for the possibility of diagnostic uncertainty due to confounding conditions.

ID: 1693

RF139: What is the chronology of symptoms of patients presenting with degenerate cervical myelopathy?

Omar Ortuno ¹ , Khadija Soufi ¹ , Allan Martin ¹

¹ University of California, Davis, Neurological Surgery, Sacramento, United States

Introduction: Degenerative cervical myelopathy is a common, debilitating, and treatable condition due to compression of the cervical spinal cord, leading to motor, sensory, and autonomic dysfunction that will continue to rise with our aging populations. DCM continues to be a clinical diagnosis corroborated with radiological findings and therefore understanding the presentation and natural history of this condition is essential to appropriate diagnosis. Currently, there are no published diagnostic criteria contributing to diagnostic delays. In this study, we aimed to assess an array of clinical symptoms for the purpose of informing the development of diagnostic criteria and understanding the onset and chronology of early symptoms experienced by DCM patients. Materials and Methods: A prospective cohort study was conducted with data collection involving validated medical and symptom history that focused on the duration (years), severity (scale of 1-10), frequency (per week), laterality (left/right/bilateral), along with pattern (constant vs intermittent), progression (none/slow/steady/rapid) and a freehand description of clinical symptoms. The clinical symptoms included headache, neck pain, back pain, hand incoordination, gait imbalance, sexual dysfunction, urinary urgency/incontinence, fecal incontinence, saddle numbness and weakness, pain and numbness in the upper (UE) or lower extremities (LE). Additionally, patients completed multiple questionnaires including mJOA, NDI, QuickDASH, EQ-5D-5L, and EQ-VAS. Results: A total of 138 DCM patients and 104 healthy controls (HC) were enrolled in the study. Amongst the DCM patients, the most common symptoms reported were neck pain (n = 118, 85.5%), headaches (n = 81, 58.7%), UE numbness (n = 75, 54.3%), gait imbalance (n = 72, 52.2%), UE weakness (n = 68, 49.3%), UE pain (n = 68, 49.3%), hand incoordination (n = 61, 44.2%) and urinary dysfunction (n = 41, 29.7%). The initial presenting symptoms of patients with DCM were neck pain (n = 46, 33.3%, mean duration 5.9 years), headache (n = 30, 21.7%, mean duration 6.1 years), UE numbness (n = 25, 18.1%, mean duration 3.7 years), UE pain (n = 21, 15.2%, mean duration 5.6 years), and UE weakness (n = 19, 13.8%, mean duration 2.5 years).The average number of symptoms patients with DCM presented with were 6.2 (median 6) with 52 patients presenting with > 1 symptom. Among the DCM patients that presented with 2+ initial symptoms (34%, n = 52), 33% (n = 17) had neck pain and UE pain, 23% (n = 6) had headache and neck pain, 23% (n = 6) had neck pain and hand incoordination, 23% (n = 6) had UE numbness and hand incoordination, 17% (n = 9) had neck pain and gait imbalance, 15% (n = 8) had UE pain and UE weakness, and 15% (n = 8) had UE numbness and gait imbalance. Conclusion: The initial symptoms that DCM patients present with are frequently neck pain, UE pain, and headaches, rather than the widely recognized neurological symptoms measured by the mJOA, which include UE sensory dysfunction, hand incoordination, gait imbalance, and urinary dysfunction. Clinicians need to pay closer attention to pain symptoms that occur in DCM, in conjunction with performing a thorough neurological examination, to accurately diagnose early DCM. These findings are important for the foundation of diagnostic criteria, which should be designed to be sensitive to very early DCM to properly identify this condition and better manage this patient population.

ID: 1859

RF140: A novel smartphone application for objective assessment of degenerative cervical myelopathy

Benjamin Steel ¹ , Pranay Singh ¹ , Erdong Cheng ¹ , Wilson Wang ¹ , Ella Majd ¹ , Haris Naveed ¹ , Olivia Tung ¹ , Isaac Becker ¹ , Sriharsha Gonuguntla ¹ , Salim Yakdan ¹ , Camilo Molina ¹ , John Ogunlade ¹ , Daniel Hafez ¹ , Wilson Ray ¹ , Mohamad Bydon ² , Caitlin Kelleher ³ , Brian Johnson ⁴ , Ryan Duncan ⁵ , Zachary Wilt ⁶ , Jetan Badhiwala ⁷ , Jacob Greenberg ¹

¹ Washington University in St. Louis School of Medicine, Neurosurgery, St. Louis, United States,

² Mayo Clinic, Neurologic Surgery, Rochester, United States,

³ Washington University in St. Louis, Computer Science and Engineering, St. Louis, United States,

⁴ Washington University in St. Louis School of Medicine, Occupational Therapy, St. Louis, United States,

⁵ Washington University in St. Louis School of Medicine, Physical Therapy, St. Louis, United States,

⁶ Rothman Orthopaedic Institute, Manahawkin, United States,

⁷ University of Toronto, Toronto, Canada

Introduction: Degenerative cervical myelopathy (DCM) is a common and debilitating condition resulting from arthritic degeneration and compression of the cervical spinal cord. It leads to various neurological deficits, particularly impairments in dexterity, gait, and balance. However, there is a lack of high-quality, objective tools for accurately measuring DCM-related disabilities, which are critical for guiding treatment decisions and monitoring patient outcomes. Smartphones and wearable technologies are equipped with a range of sensors and capabilities, including accelerometers, gyroscopes, and cameras, that are particularly well-suited for evaluating gait and upper extremity function. Based on these theoretical benefits, we developed SynapTrack, a smartphone application (app) designed to assess DCM severity using patient-performed tasks, such as gait and dexterity assessments. This study outlines SynapTrack’s initial promising results in evaluating functional impairments in DCM patients. Material and Methods: SynapTrack was developed with SwiftUI for iOS smartphones. Our efforts have centered around bootstrapping a live app (currently in Beta) for in-clinic data collection. The gait assessment algorithms were trained using data from the phone's sensors in patients with DCM and validated against objective measurements obtained from gait mats and video capture. Dexterity algorithms were developed using both self-reported assessments and data from objective tasks, such as the 9-hole peg test and a tapping task. Results: Initial testing of SynapTrack on real patients suggests that it can reliably measure key impairments associated with DCM. From gait analysis of patients with DCM (n = 6), the app accurately quantified time between steps with an average error of 17 milliseconds and demonstrated correlations with objective gait mat measurements (r = 0.92). In dexterity assessments, patients reporting greater difficulty with fine motor tasks exhibited lower performance scores on the tapping task as analyzed by backend algorithms. These preliminary results highlight the potential of SynapTrack for diagnostic and predictive purposes for patients with DCM. Additional validation testing is ongoing, and we anticipate having data from at least 20 DCM patients and non-myelopathy controls to present at the Global Spine Congress. Conclusion: The development and initial testing of SynapTrack demonstrates promise as a novel, objective tool for assessing DCM-related disabilities. By utilizing smartphone capabilities and sensors, SynapTrack offers a more precise and accessible method for evaluating disease progression and patient status. These early results support further development and validation of the app, underscoring its potential to enhance neurosurgical care for patients with DCM and advance the use of smartphone technology in clinical settings. We plan to expand testing to at-home settings and reach more patients through emerging relationships with leading clinics and care providers.

ID: 1815

RF141: Waveform analysis of intraoperative motor evoked potentials can predict functional recovery in patients with cervical spondylotic myelopathy

James P. Caruso ¹ , Ahmad Kareem Almekkawi ² , Christian Collins ³ , Faraaz Azam ⁴ , Parker Smith ⁴ , Kevin Morrill ⁴ , Mazin Al Tamimi ⁴ , Carlos Bagley ² , Salah Aoun ⁴

¹ NYU Langone, Neurosurgery, New York, United States,

² Saint Luke's Hospital, Neurosurgery, Kansas City, United States,

³ Nuvasice, San Diego, United States,

⁴ UT Southwestern, Neurosurgery, Dallas, United States

Introduction: Cervical spondylotic myelopathy (CSM) is a progressive and debilitating pathology characterized by spinal cord injury secondary to degenerative changes, often resulting in neck pain, sensory and motor deficits, limited ambulation, and decreased ability to perform activities of daily living. Intraoperative neurophysiologic monitoring is often viewed as a standard adjunct in the operative treatment of CSM. Material and Methods: A retrospective analysis was conducted on 90 patients who underwent surgical treatment for CSM. TcMEP amplitude and area under the curve (AUC) were analyzed for bilateral deltoids, abductor pollicis brevis--abductor digiti minimi (APB-ADM) and abductor hallucis--abductor digiti quinti (AH-ADQ). Functional outcomes were assessed using Odom criteria, Nurick score, and modified Japanese Orthopaedic Association (mJOA) score at immediate postoperative, 6-month, and 12-month timepoints. Mixed effects models analyzed the impact of TcMEP changes on Odom scores. Additionally, univariate linear regression analyses were performed to examine relationships between changes in TcMEP measurements and postoperative functional outcomes. Results: Patients with postoperative decreases in left deltoid amplitude and AUC had significantly worse Odom scores at 6-month follow-up compared to those with amplitude and AUC increases (p = 0.016, η² = 0.14; p = 0.021, η² = 0.14). A ≥ 50% increase in left deltoid AUC was associated with significantly better Odom scores at 6 months (p = 0.044, η² = 0.07). No significant differences were observed for right deltoid, APB-ADM or AH-ADQ recordings in the mixed effects models. Univariate linear regression analyses revealed additional significant relationships. Improvements in left APB-ADM strength were associated with better postoperative outcomes as measured by Odom's Criteria (coefficient = 0.023, p = 0.009). Improvements in right deltoid strength were associated with better outcomes at 6 months as measured by Odom's Criteria (coefficient = 0.020, p = 0.019). Furthermore, improvements in right APB-ADM strength were associated with better outcomes at 12 months as measured by the Nurick Score (coefficient = -0.019, p = 0.043), and improvements in right AH-ADQ strength were associated with better outcomes at 6 months as measured by the Nurick Score (coefficient = -0.019, p = 0.035). Interestingly, improvements in left AH-ADQ strength were associated with worse postoperative outcomes as measured by the mJOA Score (coefficient = -0.066, p = 0.029), which warrants further investigation. Conclusion: In CSM patients, postoperative decreases in left deltoid TcMEP amplitude and AUC are associated with worse functional recovery at 6-month follow-up. A ≥ 50% increase in left deltoid AUC may predict 6-month functional improvement. Additionally, changes in various muscle group strengths show significant associations with functional outcomes at different time points. Granular TcMEP analysis shows promise for anticipating postoperative outcomes in CSM patients, but some counterintuitive findings suggest the need for further research to fully understand the complex relationships between TcMEP changes and functional outcomes.

ID: 2898

RF142: Indirect posterior decompression by flaval ligamentous unbuckling after an anterior cervical discectomy and fusion - A retrospective cohort study of radiological data

Chan Hee Koh ¹ , Joseph Davids ² , Mark Nowell ² , Constantinos Thoma ² , Niels van Vucht ³ , Kia Rezajooi ⁴ , Vittorio Russo ² , Parag Sayal ² , Adrian Casey ² , George Prezerakos ²

¹ UCL Queen Square Institute of Neurology, London, United Kingdom, ² National Hospital for Neurology and Neurosurgery, Department of Neurosurgery, London, United Kingdom, ³ University College London Hospitals, Department of Radiology, London, United Kingdom, ⁴ Royal National Orthopaedics Hospital, Department of Neurosurgery and Spinal SUrgery, London, United Kingdom

Introduction: Degenerative cervical myelopathy is the commonest cause of spinal cord impairment worldwide. The spinal cord may be compressed anteriorly by disc herniations and osteophyte formations, or posteriorly by flaval ligamentous encroachment into the canal. The gold standard for treatment is surgical decompression, which can be done from anterior or posterior approaches. It has been posited that the flaval ligamentous compression may be due to buckling of the ligament from the loss of intervertebral height that is often seen in degenerative cervical myelopathy, and that therefore anterior cervical decompression and fusion (ACDF) may contribute to indirect posterior decompression through “unbuckling” and stretching of the flavum. However, there is no evidence in the literature to support this. Material and Methods: 78 consecutive patients in two British spinal surgical units with degenerative cervical myelopathy undergoing ACDF on 104 levels were included in this study. Anatomical parameters, including posterior ligamentous compression, were measured using preoperative and postoperative MRI studies. Multivariate mixed-effects linear regressions were conducted. Results: The median preoperative posterior compression was 2.7mm (IQR: 2.188 to 3.025). There was a significant decrease in posterior compression after ACDF (mean improvement: 1.1 mm, 95% CI: 0.86 mm to 1.27 mm; p < 0.0001). Multivariate regressions showed that an estimated 25.9% change in posterior compression could be expected (95% CI: 6.3% to 45.5%; p = 0.01). There was no evidence that the preoperative disc height, postoperative disc height, or the change in disc height was associated with the extent of posterior ligamentous decompression. Conclusions: This study provides the first quantitative evidence for ligamentum flavum unbuckling providing a moderate indirect posterior decompression (26%) in patients with degenerative circumferential spinal cord compression and cervical myelopathy undergoing ACDF.

RF09: NOVEL TECHNOLOGIES IN SPINE SURGERY

ID: 373

RF143: Development of a multimodal machine learning model for prediction of myelopathic symptoms in a cohort of single-level ACDF patients

Ananth Eleswarapu ¹ , Kyle Mani ² , Dan Berman ¹ , Erdi Kara ³

¹ Montefiore Einstein, Orthopedic Surgery, Bronx, NY, United States, ² Albert Einstein College of Medicine, Bronx, NY, United States, ³ Spelman College, Atlanta, GA, United States

Background: Cervical myelopathy is a progressive clinical syndrome that can be caused by cervical stenosis. However, it is common for patients with cervical central stenosis to not have myelopathic symptoms. Identifying imaging features that are predictive of myelopathic symptoms would be helpful in planning which patients need surgical decompression. Multimodal machine learning (ML) models have been used in a variety of clinical syndromes to better classify patient phenotypes and aid in decision making. Our goal in this study was to develop a multimodal machine learning (ML) model that integrates diverse data inputs with the aims of predicting myelopathic symptoms in a retrospective cohort of single-level ACDF patients at our institution. Methods: 173 single-level ACDF patients with myelopathy, radiculopathy, or combined myeloradiculopathy were extracted from our institutional EHR. Patients were labeled as “myelopathic” or “non-myelopathic”. Labels were assigned by physicians who read the pre-operative notes and assessed for mention of loss of balance or dexterity (myelopathy) in the pre operative HPI. We utilized a pre-trained convolutional neural network (CNN) to extract features from an axial MRI image at the level of the disc at the operative level. Each image was resized to 224x224 pixels, converted to a numerical array, and normalized to ensure consistent pixel value distribution. The processed images were then passed through the InceptionV3 model, and the extracted features were flattened to create a feature matrix. We employed the quanteda package for NLP within the R environment to preprocess free-text EHR inputs (past medical and surgical history and medication lists). Chief complaint, history of present illness, and physical exam were excluded to avoid “giving away” the answer as to the patient’s symptoms. The refined text was tokenized and transformed into numerical vectors using a bag-of-words approach and integrated with the tabular EHR data and the image feature matrix to create a final document-feature matrix. Tabular data extracted from the EHR included age, gender, BMI, cervical spinal level operated on, insurance payor, and serum lab results. An ensemble stacking model, incorporating several Extreme Gradient Boosted (XGBoost) ML models, was trained on this combined matrix. Area under the curve (AUC), Precision, Recall, and Brier score were recorded for model performance. Results: 173 patients (64.7% female) were extracted with a median age of 57.0 (IQR: 49.0 - 66.0) and median BMI of 30.3 $\frac{\mathit{k}\mathit{g}}{{\mathit{m}}^{\mathbf{2}}}$ (IQR: 26.7 – 34.3). The multi-modal model predicted myelopathy with AUC of 0.858, Precision of 0.866, Recall of 0.963, and Brier Score of 0.147. Important features were patient age, previous history of myelopathy, previous history of radiculopathy, hypothyroidism, prednisone usage, and BMI. Conclusions: A multimodal ensemble stacking machine learning model can utilize the large amount of data in EHRs to accurately predict myelopathic symptoms. While machine-learning risk calculators have been developed previously in orthopaedics using structured data, our innovative approach allows for extraction of meaning from free text and images. Future work includes prospectively validating the models within our institution and the assessment of whether a similar approach can be used to predict improvement in symptoms after surgery.

ID: 2403

RF144: Clinical and radiographic outcomes of “target zone” cement injection technique for osteoporotic vertebral compression fracture

Chen Jin ¹ , Liang Tang ¹ , Jiang-Ming Yu ¹ , Xiao-Jian Ye ¹

¹ Tongren Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China

Introduction: Osteoporotic vertebral compression fracture (OVCF) is regarded as one of the most common complications of osteoporosis. Percutaneous vertebroplasty (PVP) can provide an excellent therapeutic effect, including immediate pain relief, biomechanical stability and restoration of vertebral height. However, previous studies reported that the incidence of refracture of cemented vertebrae after PVP ranged from 0.56 to 27.63%, and even a surprising 63% in some cases. Unfortunately, so far, no effective surgical technique has been described to avoid the refracture of cemented vertebrae. This study aims to assess the feasibility of the “target zone” injection technique, and compare the clinical efficacy of reducing the incidence of refracture after PVP between “target zone” cement injection and conventional injection method. Material and Methods: In this study, 160 patients who were treated with PVP, were enrolled. The patients were grouped into two groups based on type of procedure performed: (1) “target zone” group, (2) control group. In “target zone” group, once the needle tip passed through the pedicle and located at one-fourth of the posterior part of the affected vertebral body, the entry stopped. Then, we pulled out the inner core and inserted the curved needle core. Under lateral fluoroscopy view, the curved needle core was adjusted to face the upper or lower endplate and located at the fracture line depending on the position of the fracture line. Meanwhile, the curved needle core crossed the midline of the vertebral to the projection of contralateral pedicle on the posteroanterior view. The polymethyl methacrylic (PMMA) was prepared at appropriate viscosity and was slowly injected into the fracture vertebrate body. By turning the direction of the flexible thruster, the bone cement was filled the vertebrate evenly and made contact with the upper and/or lower endplates. In control group, the PMMA cement was directly injected into the vertebrate using conventional straight annular tubes. The following main indexes were measured: intravertebral cleft, initial vertebral compression rate, the initial vertebral compression rate, initial vertebral height reduction rate, vertebral height recompression rate, and cement distribution pattern. Results: Refracture rate in “target zone” group (4.2%) was significantly lower compared with that in control group (12.3%) (p = 0.027). Intravertebral cleft was found in 19 subjects in “target zone” group, and 31 subjects in control group (p = 0.633). The initial vertebral compression rate in “target zone” group (33.0 ± 7.5%) showed no significant difference with that in control group (35.0 ± 8.9%) (p = 0.257). Although the initial vertebral height reduction rate was found higher in “target zone” group (5.5 ± 0.83%) than that in control group (4.3 ± 0.77%), no significant difference was achieved (p = 0.056). The vertebral height recompression rate in “target zone” group was 1.60 ± 0.76%, which showed remarkable lower in comparison with that in control group (4.10 ± 0.55%) (p = 0.029). Conclusion: This study provides a novel “target zone” cement injection technique, which is beneficial to achieve ideal distribution pattern of cement and to avoid refracture of cement vertebrate.

ID: 1104

RF145: Low-cost augmented reality system for endoscopic spine surgery: a step-by-step guide

Facundo Van Isseldyk ^1,2 , Marcus Vinícius Serra ³ , Alberto Gotfryd ⁴ , Lisandro Rodriguez Sattler ⁵ , Cristian Ricardo Correa Valencia ⁶ , Julio Bassani ⁷ , Jin-Sung Kim ^2,8

¹ Hospital Privado de Rosario, Neurosurgery, Rosario, Argentina,

² Endospine Academy, Balgrist University Hospital, Zürich, Switzerland,

³ Santista Institute of Neurosurgery and Spine, Santos, Brazil,

⁴ Santa casa de São Paulo Medical School and Hospital, Sao Paulo, Brazil,

⁵ Asociación Española Primera de Socorros Mutuos, Montevideo, Montevideo, Uruguay,

⁶ University of La Frontera, Orthopedic Department, , Temuco, Chile,

⁷ Hospital Italiano, Buenos Aires, Argentina,

⁸ St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Department of Neurosurgery , Seoul, South Korea

Introduction: Endoscopic surgery has gained increasing popularity and acceptance over the past 10 years. Its high-quality imaging combined with minimal invasiveness has made it an attractive technique for spinal surgeons. However, intraoperative orientation is a key factor in performing these procedures and remains one of the main challenges in the learning curve. To address this, surgeons need access to a large amount of information: the patient’s CT scan, MRI, fluoroscopic images, and the video feed from the endoscopic camera. Additionally, in complex cases, 3D reconstruction of the spine may be required, which can necessitate up to five separate displays at the same time. This makes it difficult to achieve a comfortable and ergonomic setup in the operating room. Video systems are expensive and require a significant amount of physical space. To ensure versatility, high-definition displays must be mounted on supports that allow six degrees of movement and can be easily relocated. We present a step-by-step guide for installing a low-cost augmented reality system that improves ergonomics in the operating room, displaying all the necessary information for surgery on virtual displays that can be easily adapted to the surgeon’s needs. Material and Methods: The augmented reality system consists of a headset, head strap, battery, capture card, and a dedicated router. All components are available worldwide. The total cost is less than 1,000 US dollars, and the system can be connected to any laptop with a USB input. The software required for its operation is free. Videos and photos demonstrating its functionality are available for presentation. Results: The image quality experienced showed no perceptible differences compared to traditional displays. No signal interruption was observed. The latency was less than 30 milliseconds. Ergonomics and movement in the operating room were significantly improved, with an 80% reduction in the number of required displays. Prolonged use of the head strap may cause some discomfort, which is partially alleviated by a built-in fan system. Conclusion: The augmented reality system described offers a low-cost alternative to traditional displays used in endoscopic spinal surgery.

ID: 2540

RF146: State of the machine: a critical analysis of use of machine learning for diagnosis and prognostication of degenerative cervical myelopathy - What have we learned? Where are we going?

Negeen Halabian ¹ , Mohammed Ali Alvi ^1,2 , Jiawen Deng ¹ , Karlo Pedro ^1,2 , Michael Fehlings ^1,2

¹ University of Toronto, Toronto, Canada,

² University Health Network, Toronto, Canada

Introduction: Traditional prognostic and diagnostic models for predicting the neurological, functional, and quality of life outcomes in patients with degenerative cervical myelopathy (DCM) typically involve logistic/linear regression modeling of accessible patient-level predictors. These predictors include patient demographics, disease severity scores (such as assessments using the modified Japanese Orthopedic Association score), and subjective imaging findings like compression or signal changes. In contrast, machine-learning (ML) powered models can identify complex, non-linear relationships between predictors to capture correlations otherwise elusive with statistical methods. This capability offers the potential for more individualized prognostic and diagnostic predictions for DCM-patients, which could improve outcomes. We conducted a scoping review to summarize and critically appraise the current literature on the use of ML models in DCM diagnosis and management. Material and Methods: We conducted this scoping review following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extension for Scoping Reviews (PRISMA-ScR) checklist. A database search was conducted in MEDLINE, EMBASE, Cochrane Library, and Web of Science to identify studies reporting the development and validation of ML models (both supervised and unsupervised) for facilitating the diagnosis, prognosis, and/or treatment of DCM. The risk of bias in the included studies was assessed using the Prediction Model Risk of Bias Assessment Tool (PROBAST). Results: From 577 records, 55 studies were included with the earliest being published in 2015, and the majority (91%) published after 2021. Diagnosis and phenotyping of DCM were the most commonly studied research topics (n = 20). Surgical prognosis was the second most common application with 17 studies, followed by 11 studies aiming to classify DCM severity. The included studies demonstrated that ML models can enhance DCM diagnosis, prognosis, and management by identifying specific clinical factors, particularly when multiple data modalities are used. Deep learning algorithms (such as radiomics) combined with advanced imaging techniques - like diffusion tensor imaging (DTI), and diffusion basis spectrum imaging (DBSI) - identified imaging biomarkers like T2 texture features and wavelet-LL variance, which correlated with disease severity and predicted postoperative recovery, thus improving prognostic accuracy. ML models also identified patient-specific predictors of surgical outcomes like fat infiltration, higher BMI, and other comorbidities—aiding in risk stratification and surgical decision-making. Furthermore, ML algorithms discovered novel risk factors for postoperative complications, contributing to individualized patient care and informing preoperative planning. Unsupervised ML algorithms identified distinct patient phenotypes within the mild DCM group that have better post-surgical outcomes. However, risk of bias assessments revealed that most studies had a high risk due to poor adherence to reporting guidelines and absence of external validation, raising concerns about transparency and generalizability. Methodological issues, such as inadequately described feature selection processes and unclear reporting of predictors, further limited reproducibility. Conclusion: ML models have the ability to enhance diagnosis and management by improving detection accuracy, predicting disease severity and postoperative outcomes, and enabling personalized treatments. However, methodological flaws limit their generalizability and clinical application. Future research must focus on methodological rigor, better reporting, and collaboration between data scientists and clinicians to develop robust, clinically relevant ML models.

ID: 2380

RF147: Integration and application of artificial intelligence and surface topography in scoliosis screening

Rohan Tiwari ¹ , Bhavuk Garg ¹ , Deepak Joshi ² , Barath Kumar ²

¹ ALL India Institute of Medical Sciences, Orthopaedics, New Delhi, India,

² Indian Institute of Technology, Biomedical Engineering, New Delhi, India

Introduction: Traditional scoliosis diagnosis typically relies on radiographic imaging, which involves exposure to ionizing radiation, posing potential health risks with repeated use. However, recent advancements in 3D surface topography, such as the application of Microsoft Kinect V2.0, offer a promising radiation-free alternative. The Kinect V2.0 captures highly detailed 3D images of the body's surface using time-of-flight technology. By integrating this technology with artificial intelligence (AI) and machine learning (ML), diagnostic accuracy can be significantly improved. Automated detection of anatomical landmarks and precise calculation of spinal metrics can enhance the efficiency of scoliosis assessments. This study explores the synergy of AI and 3D surface topography to deliver a cost-effective, efficient, and radiation-free approach to scoliosis assessment, with an emphasis on minimizing radiation exposure. Material and Methods: This study involved 25 participants recruited from a specialized orthopaedic hospital. The Kinect V2.0 sensor was used to capture 3D surface topography of the participants' backs, with data processed to measure key spinal metrics such as thoracic kyphosis, lumbar lordosis, and Cobb angles. Both concurrent and criterion validity were assessed. Concurrent validity was evaluated by comparing Kinect measurements with clinical assessments, while criterion validity involved comparing Kinect data with recent spinal radiographs. The procedure included placing adhesive markers on anatomical landmarks (C7, L1, and bilateral PSIS) and capturing images from various distances to enhance generalizability during machine learning (ML) training and scoliosis classification. Results: The Kinect V2.0 provided valid measurements for thoracic kyphosis but demonstrated less consistent correlation for lumbar lordosis when compared to traditional radiographic methods. AI-driven analysis of Kinect data was effective in detecting trunk rotation, which is useful for scoliosis assessment. Conclusion: The Kinect's non-invasive and radiation-free approach offers advantages in cost, portability, and safety. Despite these benefits, the study identifies the need for further refinement of AI algorithms to improve measurement accuracy and clinical reliability.

ID: 1241

RF148: Full endoscopic neuronavigated decompression of craniocervical junction with duraplasty in Chiari malforamtion Type I: description of a novel treatment

Benedikt Trnovec ¹ , Juraj Sutovsky ¹ , Radoslav Hanzel ¹ , Martin Hanko ¹ , Zuzana Humpolcova ¹ , Svorad Trnovec ² , Anna Sebova ³ , Kamil Kolejak ¹

¹ BORY Hospital, Neurosurgery and Spine Surgery, Bratislava, Slovakia,

² University Rostock, Neurosurgery, Rostock,

³ BORY Hospital, Radiology, Bratislava, Slovakia

Background: Open surgery in patients with CM I. relates to risks such as neurological impairment, CSF leakage, muscle trauma, development of hydrocephalus with shunt dependency, wound healing complications, and postoperative neck pain. The advent of high-end endoscopic equipment enables new strategies in extraordinarily complex areas like craniocervical junction and new strategies challenging standardized procedures to prove its effectiveness. Research Question: Introducing a novel technique and comparison of safety and clinical benefits to standard open treatment. Design: Monocentric study Methods: 4 Adult patients with CM I. with- or without Syringomyelia were treated via full endoscopic surgery with neuronavigational assistance and intraoperative neuromonitoring. Suboccipital craniectomy and C1 laminectomy followed by durotomy and dural patch performed in full endoscopic fashion. Follow up in 3, 6, 12 and 24 weeks with clinical check-up, neurological and radiologic examination. Results: We state no neurological impairment after endoscopic treatment. Intraoperative no signs of decreasing SEPs, MEPs, caudal brainstem nerves, we state increase of BAEPs. Common postoperative signs were persistent: mild or strong headache, retrobulbar pressure, ataxia, hypesthesia on limbs, ataxia, episodic fever. In the whole group of patients these symptoms were dramatically regredient within the postoperative check up in the 12^th week. We stated sufficient decompression based on radiologic criteria in the whole cohort. No wound healing complications, nor CSF leak, or infection stated in the long term follow up. Discussion: The duration of the surgery in terms of introduction a novel method is still incomparable with the standard open treatment. On the other hand, there were no readmissions, nor reoperations needed. Based on the clinical, functional and radiologic outcome we state the safety and efficacy of full endoscopic management in patients with CM I.

ID: 2902

RF149: Development and validation of a novel AI framework using NLP with LLM integration for clinical data extraction and postoperative billing automation: an analysis of 68,260 records

Mert Dagli ¹ , Hasan Ahmad ¹ , Daksh Chauhan ¹ , Ryan Turlip ¹ , Kevin Bryan ¹ , Connor Wathen ¹ , Yohannes Ghenbot ¹ , John Arena ¹ , Joshua Golubovsky ¹ , John Shin ¹ , Ali Ozturk ¹ , William Welch ¹ , Jang Yoon ¹

¹ University of Pennsylvania, Neurosurgery, Philadelphia, United States

Introduction: Manual chart review (MCR) for extracting surgical data from Electronic Health Records (EHRs) is time-consuming, prone to error, and a significant bottleneck in clinical research and quality control. This study aimed to develop and validate a novel artificial intelligence (AI) framework that integrates Natural Language Processing (NLP) with a Large Language Model (LLM) to automate the extraction of relevant clinical data from spinal surgery EHRs and automate postoperative billing. By leveraging GPT-4 Turbo, the system was designed to streamline the labor-intensive process of data extraction, reduce errors associated with MCR, and ensure time and cost efficiency. Material and Methods: This study adhered to the Transparent Reporting of Multivariable Prediction Models for Individual Prognosis or Diagnosis + Artificial Intelligence (TRIPOD+AI) guidelines. We utilized three institutional databases comprising thoracolumbar adult spinal deformity cases (N = 646), lumbar endoscopic spinal surgery cases (N = 182), and lumbar decompression cases (N = 5,998). The AI framework integrating NLP with an LLM was replicated ten times to address hallucinations, totaling an analysis of 68,260 records across the ten replications. The primary outcome was the accurate identification of surgical details, including surgery type, levels operated, number of disks removed, levels fused, incidental durotomies, and postoperative billing. Secondary objectives explored time efficiency, tokenization lengths, and costs. Performance metrics such as accuracy, sensitivity, area-under-curve receiver-operating-characteristic (AUC-ROC), F1-score, and positive predictive value (PPV) were calculated with 95% confidence intervals using bootstrapping. Results: The AI framework successfully extracted relevant clinical data and automated postoperative billing with high accuracy across all datasets, outperforming the human control. The NLP+LLM system achieved a sensitivity of 0.999 and an AUC-ROC of 0.997 for clinical data extraction, demonstrating similar performance in billing automation. Postoperative billing automation achieved comparable accuracy and efficiency. The use of a majority vote, utilizing data from the deduplicated (ten replications) run, eliminated errors from singular runs. Tokenization and cost analyses indicated substantial time savings (38.8 seconds per case) and cost savings ($9.04 per case) compared to manual chart reviews. Feature importance analysis revealed that surgery type and levels operated were the key variables in data extraction. Conclusion: We demonstrated that the integration of NLP and LLM within an AI framework can significantly improve the accuracy, time, and cost efficiency of clinical data extraction and postoperative billing. These results suggest the potential for widespread adoption of AI-based automation in healthcare. Further research will focus on enhancing the sensitivity and validating the model in broader clinical settings to further optimize billing automation and clinical documentation processes.

ID: 1221

RF150: Virtual, augmented, and mixed reality applications for surgical rehearsal, operative execution, and patient education in spine surgery: a scoping review

Tim Bui ¹ , Miguel Ruiz Cardozo ¹ , Karma Barot ¹ , Michael Kann ^1,2 , Karan Joseph ¹ , Sofia Lopez-Alviar ¹ , Gabriel Trevino Verastegui ¹ , Samuel Brehm ¹ , Alexander Yahanda ¹ , Camilo Molina ¹

¹ Washington University School of Medicine, Neurological Surgery, St. Louis, United States,

² University of Pittsburgh School of Medicine, Pittsburgh, United States

Introduction: Advances in virtual reality (VR), augmented reality (AR), and mixed reality (MR) technologies have led to their increasing use in various medical specialties. Recently, these technologies have enabled novel methods of simulation, practice, and education in spine surgery, offering creative supplements for rehearsal in physician training and patient education in clinical care. VR has primarily been used for training and simulation while AR is often utilized for assisting surgical navigation and execution. MR, while less prevalent than the other two modalities, offers a unique blend of the virtual and physical space with potential for fostering a more integrative perspective. The objective of this review was to explore current uses of VR, AR, and MR in spine surgery, focusing on their roles in surgical rehearsal, operative execution, and patient education. Material and Methods: A systematic scoping review was conducted following PRISMA guidelines. The review searched for studies published in English that explored VR, AR, or MR applications in spine surgery, including resident training, preoperative planning, surgical execution, and patient education. The databases PubMed and Scopus were searched on January 23, 2023. A total of 228 studies were initially identified, and after applying inclusion and exclusion criteria, 46 articles were selected. The study quality was assessed using different tools: the Medical Education Research Study Quality Instrument (MERSQI) for education research, the Quality Appraisal for Cadaveric Studies (QUACS) scale for cadaveric studies, and the Joanna Briggs Institute (JBI) critical appraisal tools for clinical studies. Results: Of the 46 articles included in the review, 14 studies focused on VR applications, 27 on AR, and 5 on MR. These studies comprised various research designs, including clinical case studies, case series, cadaveric studies, and randomized controlled trials. VR was primarily used for resident training while AR showed the most promise in enhancing the accuracy of spine surgeries. The most simulated procedure was navigation for pedicle screw placement and spinal decompression in both AR and VR. MR, although less commonly studied than its AR/VR counterpart, demonstrated potential for further improving surgical precision by integrating virtual models with the physical operative environment. In educational settings, both AR and VR significantly improved trainees' visuospatial skills and understanding of complex spine anatomy. Conclusion: VR, AR, and MR have demonstrated significant potential in spine surgery with its recent advances in medical application. VR provides robust platforms for surgical rehearsal and patient education, allowing for repeated practice without patient risk. AR, with its ability to overlay holographic models onto the real-time surgical field, enhances precision and safety during operations. MR, while still in its infancy, shows promise in integrating virtual and physical environments for more interactive surgical experiences. These technologies are likely to play an increasing role in medical training and surgical practice, contributing to improved patient outcomes and reduced learning curves for surgeons. Future research should focus on overcoming the current limitations such as the lack of haptic feedback in VR or the cost barriers currently preventing use of these technologies in the clinical practice of resource-limited areas.

ID: 1398

RF152: Assessing the utility, limitations, and implementation of machine learning in scoliosis management: a systematic review

Jibran Khan ¹ , Abdelrafour Houdane ¹ , Amro Hajja ¹ , Joseph Nassar ² , Daniel Alsoof ² , Bassel Diebo ² , Zeeshan Sardar ³ , Muhammad Abd-El-Barr ⁴ , Anouar Bourghli ⁵ , Faisal Konbaz ⁵

¹ Alfaisal University College of Medicine, Riyadh, Saudi Arabia,

² Warren Alpert Medical School of Brown University, Department of Orthopedic Surgery, Providence, United States,

³ Columbia University Medical Center, The Spine Hospital at New York Presbyterian, Department of Orthopedic Surgery, New York, United States,

⁴ Duke University Medical Center, Department of Neurosurgery, Durham, United States,

⁵ King Faisal Specialist Hospital and Research Center, Department of Spine Surgery, Riyadh, Saudi Arabia

Introduction: Machine learning (ML) has revolutionized medical research, recently so in managing scoliosis. It allows automated assessment of outcomes such as diagnosis, disease progression, and treatment response. This study aimed to review the application of ML in the diagnosis, operative outcomes, prognosis, and risk assessment across all types of scoliosis, emphasizing understanding the applications, limitations, and the challenges in implementation of ML in scoliosis practice. Material and Methods: A systematic review of the literature was conducted following the PRISMA guidelines and was registered in the Prospective Register of Systematic Reviews (PROSPERO) database. The literature search included the PubMed, Embase, and Google Scholar databases. Studies since 2019 were included if they used ML models in scoliosis management. Conference abstracts, non-retrievable articles, animal or cadaveric studies, duplicates, and studies that did not meet the inclusion criteria were excluded. Data extraction focused on the type of scoliosis, sample size, ML model architecture, model development, training data, cross-validation, the utility of the model, single- or multi-center study design, clinical implementation, and study limitations. Results: The study included 63 articles that underwent full-text review after excluding duplicates, conference abstracts, and studies that did not meet the inclusion criteria. The most commonly studied disorders were adolescent idiopathic scoliosis (n = 48), adult spinal deformity (n = 15), early-onset scoliosis (n = 2), and other disorders (n = 3), with one study not specifying. The utility of the models was primarily in diagnosis/classification (n = 38), followed by perioperative management (n = 11), prognosis (n = 7), and risk assessment (n = 7). The most frequently used machine learning models included convolutional neural networks (n = 38), random forest (n = 11), and support vector machines (n = 9). For training, most studies used only radiographic data (n = 48), with some using only clinical data (n = 6), and others using both (n = 9). Only 16 studies reported external validation, while none of the studies implemented the model in their practice. Common limitations reported were small sample size, artifacts obscuring images, potential selection bias, limited variety in disease severity, certain parameters not being included, lack of patient diversity, missing information, varying accuracy with curve site and severity, and lack of external validation. Conclusion: The current state of machine learning in scoliosis management is promising, showing potential for improving diagnostic accuracy and optimizing treatment strategies for both pediatric and adult patients. However, significant challenges remain, including limited generalizability, lack of external validation, and difficulties in implementation. To fully understand the benefits of ML in scoliosis care, larger, multi-center studies with more validation and effective implementation strategies are needed.

ID: 2803

RF153: 3D porous titanium microspheres for the treatment of vertebral compression fracture: analysis of clinical efficacy and safety profile

Giuseppe Barbagallo ¹ , Giacomo Cammarata ¹ , Angelo Basile ¹ , Giulio Bonomo ¹ , Carmelo Vitaliti ¹ , Francesco Certo ¹

¹ University Hospital “G. Rodolico - San Marco”, Neurosurgery, Catania, Italy

Introduction: Kyphoplasty has evolved as a minimally invasive surgical technique for the treatment of vertebral compression fractures (VCFs), offering pain relief and spinal stabilization. The use of titanium microspheres in kyphoplasty has been proposed to provide a more durable augmentation material with potential benefits over traditional polymethylmethacrylate (PMMA). This study aims to assess the efficacy and safety of titanium microspheres in kyphoplasty for patients with VCFs. Material and Methods: We retrospectively retrieved all 32 patients, 16 males and 16 females, treated with kyphoplasty using titanium microspheres at our institution between January 2022 and January 2024. Patient demographics, fracture characteristics, procedural details, and pre- and postoperative clinical outcomes, including pain scores (NRS) and quality of life (SF-36), were extracted from the medical records. All patients were studied preoperatively with spine X-ray in supine position (AP and LL), MRI and spine CT. Vertebral heigh restoration was evaluated measuring Vertebral Body Height (VBH) in anterior, medial, and posterior vertebral body. Wedge Angle (WA), measured as the angle between the upper endplate and the lower endplate of the fractured vertebra, and Kyphosis Angle (KA), measured as the angle between the inferior endplate of the intact vertebra above and the superior endplate of the intact vertebra below, were also measured. Intraoperative and postoperative adverse events were documented. Data statistical analysis was performed using RStudio version 23.12.0. Results: The study included 32 patients with a mean age of 55 years and 5 months ± 19.3 (range 15 - 82). The mean follow-up was of 15 months. For each patient, the number and location of VCFs level treated were recorded. 28 Patients had an A1 fracture and 4 an A3 fracture according to AO Spine Thoracolumbar Classification System. Significant pain reduction was observed postoperatively with mean NRS scores decreasing from 7.18 preoperatively to 2.95 postoperatively (p < 0.001). Post-operative ODI has shown an important improvement with mean 17.84% ± 16. The SF-36 scores showed marked improvement in physical function and bodily pain domains at 12-month follow-up. KA values showed a significant postoperative decrease, with the mean reduction from 11.09 preoperatively to 7.99 postoperatively (p = 0.007). Furthermore, there was statistical significance between pre- and postoperative values of anterior VHB (p = 0.029). There wasn’t statistical significative difference between Cranial and Caudal Vertebral Body Height measurements before and after surgery (p = 0.766 and p = 0.512). There were minimal procedural complications, with no reports of microsphere leakage or migration. In one case post-surgical kyphosis required Th12 somatectomy and trans-thoracic anterior arthrodesis surgery with expanding cage and percutaneous vertebral stabilization of the Th11-L1 segments, while in another case a Th11-L3 for L1 fracture was required. Conclusion: Kyphoplasty with titanium microspheres appears to be an effective and safe option for the treatment of VCFs, offering significant pain relief and improved quality of life. The use of titanium may provide an advantageous alternative to PMMA, with potentially fewer long-term complications. Further prospective studies are warranted to validate these findings and to compare the outcomes with other augmentation materials.

ID: 1191

RF154: Use of Smiley face technique for pars interarticularis repair

Diego Alvarez ¹ , Francoise Descazeaux ¹ , Carlos Huaiquilaf ¹

¹ Hospital Dr Exequiel Gonzalez Cortes, Servicio de Traumatología, Santiago, Chile

Introduction: Interbody fusion in children and adolescents often leads to stiffness, reduced range of motion, and adjacent level disease, with an 8.5% complication rate, including surgical site infection, lung damage, and pseudoarthrosis. These risks are especially pertinent in surgically managed spondylolysis, where the goal is to avoid fusion and maintain mobility. Various pars repair techniques exist, but they tend to have high complication rates. This study presents a case series of patients undergoing spondylolysis repair using the Smiley face technique (Gillet technique), a method aimed at preserving interbody mobility while providing greater mechanical resistance and reducing the bone defect. Materials and Methods: This retrospective case series involved seven patients with spondylolysis refractory to medical management, without spinopelvic imbalance or disc degeneration. The Smiley face technique was employed for pars repair. Patients were positioned prone with hyperextension of the hips to promote reduction. A midline incision was made, and the lamina and fatty-fibrous tissue at the site of lysis were identified. Care was taken to protect the joint capsule while dissecting fibrous tissue to expose the lysis. Pedicle screws were placed using the Freehand technique with radioscopic guidance. The fusion bed was prepared at the upper and lower poles of the lysis site, and a U-shaped bar was molded and passed behind the joints, deep to the interspinous process. The lysis was reduced by progressively lowering the bar bilaterally, achieving reduction while preventing pullout. Data on postoperative recovery, pain scores, and complications were collected. Results: The patients in the case series had a mean age of 14.5 years, all presenting with low back pain (100%) and a visual analog scale (VAS) pain score of 6.6/10 upon admission. All patients had altered activities of daily living (ADL) and were unable to participate in sports. Prior to surgery, 50% of patients underwent prolonged kinetic therapy (mean 117 days) with minimal improvement (post-therapy VAS 6.5/10). Following surgery, the average postoperative VAS score improved to 2.5, with a mean hospital stay of 3.3 days. Only two patients required postoperative kinetic rehabilitation. One patient experienced asymptomatic non-union at the one-year follow-up. The overall complication rate was low, and the technique was well-tolerated by all patients. Conclusion: The Smiley face technique (Gillet technique) for pars repair in spondylolysis is an effective surgical option that preserves interbody mobility and provides good clinical outcomes. This method is relatively easy to learn, with short surgeries, minimal complications, and rapid recovery. Based on this case series, pedicle fixation-based pars repair techniques, particularly the Gillet technique, should be preferred for treating refractory spondylolysis in adolescents, offering a balance between mechanical stability and the preservation of mobility.

ID: 1268

RF155: Clinical accuracy and complications of augmented reality-assisted pedicle screw placement in 104 consecutive cases

Richard Price ¹

¹ University of California Davis, Sacramento, United States

Introduction: Augmented reality (AR) utilizes optical projections into the user’s field of view to create a visual overlay in the visual field. Recently, several AR spinal navigation systems have been approved for thoracolumbar pedicle screw placement. Cadaveric studies and initial human studies show accuracy similar to robotic navigation system. However, large validation studies are lacking or only include open or percutaneous pedicle screws. This series extensively evaluates accuracy and complications in 104 consecutive open and percutaneous thoracolumbar fusion cases. Material and Methods: This is a retrospective review of 104 consecutive thoracolumbar spinal instrumentation procedures utilizing augmented reality (Augmedics xvision) for pedicle screw placement from May 2022 thru August 2024. In this analysis we examine clinically accuracy of pedicle screws and complications related to pedicle screw placement. Clinical accuracy was determined by intra-operative CT or post-operative Xray. Results: A total of 727 pedicle screws were placed during 104 cases by a single surgeon. Twenty-seven were traditional open cases, while 77 cases utilized percutaneous placement of pedicle screws. Thoracic pedicle screw accuracy was 98% (251/256) and lumbar pedicle screw accuracy was 99.8% (460/461). There were no inaccurate S2AI screws (10/10). Overall accuracy was 99.2%. Screw inaccuracies only occurred in three percutaneous cases. There were no screw inaccuracies in open cases. The use of augmented reality was aborted during two percutaneous cases for perceived inaccuracies. During the follow up period there were no screw related complication or need for revision surgery. There was one post-operative hematoma in this series that was not related to pedicle screw placement. Conclusion: To date, this is the largest series examining 727 open and percutaneous pedicle screws placed by the same surgeon. Overall accuracy in combined open and percutaneous cases was 99.2% which is consistent or better than published robotic navigation accuracy. There were no screw related complications or revision surgery performed form screw inaccuracy. The use of AR is safe and accurate for the placement of pedicle screws in the thoracolumbar spine. AR is non-inferior to robotic navigation for pedicle screw placement.

ID: 663

RF156: Motion preservation for unstable discoligmentous injuries of the cervical spine - an alternative to ACDF? - a biomechanics cadaver study

Adrian Cavalcanti Kußmaul ¹ , Titus Kuehlein ¹ , Kistler Manuel ¹ , Becker Christopher ¹ , Warnecke Daniela ² , Jan Wulf ¹ , Holzapfel Boris ¹ , Böcker Wolfgang ¹ , Greiner Axel ¹

¹ Department of Orthopaedics and Trauma Surgery, Musculoskelettal University Center Munich (MUM), University Hospital, LMU Munich, Munich, Germany,

² Arthrex GmbH, Orthopedic Research Department, Munich, Germany

Introduction: Currently, the gold standard for the treatment of AO type B3 cervical spine injuries is anterior cervical discectomy and fusion (ACDF), leading to an iatrogenic spondylodesis of the affected segment and ultimately bearing the risk of long-term morbidity due to implant related complications and adjacent segment disease. The purpose of this study was to evaluate the biomechanical properties of a combination of a cervical total disc replacement (CTDR) with anterior tape augmentation for the treatment of AO type B3 injuries. The tape augmentation is hereby meant to imitate the function of the ruptured anterior longitudinal ligament (ALL). Biomechanical testing was conducted in direct comparison to ACDF. Material and Methods: 14 human cadaveric cervical spine specimens (C5/6) were biomechanically tested under four different conditions: native, after simulation of an AO type B3 injury, after ACDF and with the combination of a CTDR + Tape. All conditions were tested in the sagittal, frontal, and transversal plane with a load of 2.25Nm and recorded using an optical measurement system. The mean value of range of motion (ROM) was calculated and statistical analysis performed to identify differences in ROM and the neutral zone. Results: In flexion/extension, native testing showed a mean deflection of 11.2° ± 3.3°, the AO type B3 injury of 13.7° ± 2.9°, the ACDF of 6.7° ± 3.8° and the CTDR + Tape of 9.3° ± 2.9°. Lateral bending revealed a ROM of 6.8° ± 2.7° in the native, 7.7° ± 2.4° in the injured group and 4.7° ± 2.8° after ACDF, as well as 5.6° ± 2.4° after CTDR + Tape. The rotation showed a mean ROM of 5.6° ± 2.8° in the native and 5.8° ± 2.6° in the injured group, 4.0° ± 2.1° after ACDF and 6.3° ± 2.8° after CTDR + Tape. Conclusion: The combination of a CTDR + FiberTape proved to adequately stabilize an AO type B3 cervical spine injury while maintaining micro-mobility and approaching physiological segment mobility. Therefore, in this ex vivo setting it presents a feasible alternative to ACDF. Further biomechanical and clinical studies are needed to evaluate this new method.

ID: 746

RF157: Sagittal adjusting screw system improves the alignment correction and fracture reduction in thoraco-lumbar vertebral fractures

Yusuke Dodo ¹ , Ichiro Okano ¹ , Kento Shiga ² , Yoshihisa Komuro ³ , Joji Ogawa ⁴ , Koki Tsuchiya ¹ , Chikara Hayakawa ¹ , Yuki Midorikawa ³ , Tomoyuki Ozawa ² , Yoshifmi Kudo ¹

¹ Showa University, Orthopaedic Surgery, Tokyo, Japan, ² Tokyo Kyosai Hospital, Orthopaedic Surgery, Tokyo, Japan, ³ Ohtanishinouchi Hospital, Orthopaedic Surgery, Fukushima, Japan, ⁴ Tokyo Metropolitan Hiroo Hospital, Orthopaedic Surgery, Tokyo, Japan

Introduction: Thoraco-lumbar (TL) vertebral fractures with malalignment or fragments within the spinal canal are commonly managed using reduction techniques such as ligamentotaxis, which aim to enhance long-term outcomes. The sagittal adjusting screw (SAS) system, a monoaxial screw system featuring a fixed screwhead with a concave sliding saddle, facilitates lordotic sliding of the rod in the sagittal plane following screw insertion. The SAS system permits motion exclusively in the sagittal plane, thereby providing secure fixation and enabling angular reduction. Additionally, specialized trauma reduction devices designed for use with the SAS system are available. This study aims to evaluate the efficacy of the SAS system in correcting alignment and reducing fractures in TL vertebral fractures, and to compare its performance with that of the multi-axial screw (MAS) system to assess the relative advantages of the SAS system. Materials and Methods: A retrospective review was conducted on the records of patients who underwent spine surgery for traumatic vertebral fractures between January 1, 2017, and February 29, 2024, at three medical facilities. The study included patients who received posterior fixation using either the Sagittal-adjusting screw (SAS) system with a trauma reduction device or the multi-axial screw (MAS) system. Data collected encompassed patient demographics, surgical details, and pre- and post-operative radiographic assessments. These assessments included measurements of regional kyphosis angle (RKA), percentage loss of anterior vertebral body height (%AVB), AO classification, TLICS score, and Load Sharing Classification (LSC) scores. The reduction of malalignment achieved with the SAS and MAS systems was evaluated by comparing pre- and post-operative RKA and %AVB. Simple and multivariable logistic regression analyses were performed to compare outcomes between the SAS and MAS systems. Results: A total of 97 patients were included in the study, with 48 undergoing treatment with the multi-axial screw (MAS) system and 49 with the Sagittal-adjusting screw (SAS) system. Of these, 60 patients were followed up for one year. The SAS group exhibited a significantly greater reduction in post-operative percentage loss of anterior vertebral body height (%AVB) compared to the MAS group (MAS: -9.6%, SAS: -25.9%, p < 0.001). This reduction in %AVB was sustained at one year postoperatively (MAS: -5.45%, SAS: -21.2%, p = 0.001). Additionally, the SAS group demonstrated more pronounced changes in post-operative regional kyphosis angle (RKA) compared to the MAS group (MAS: -2.1°, SAS: -7.0°, p = 0.001). Multivariable analysis identified the use of the SAS system and the reducibility of sagittal deformation in the LSC as independent factors associated with post-operative %AVB. Conclusion: The SAS system demonstrated a greater reduction in post-operative percentage loss of anterior vertebral body height (%AVB) and regional kyphosis angle (RKA) compared to the MAS system. Notably, the reduction in %AVB achieved with the SAS system was sustained at one year follow-up, suggesting that the SAS system may enhance reduction outcomes for thoraco-lumbar vertebral fractures. Further research is warranted to evaluate the long-term benefits of the SAS system and its impact on additional clinical outcome measures.

ID: 1120

RF158: A safe, novel and ingenious method for autologous bone graft storage in spine surgery with constrained resources - Operative site as the bone bank

Ravi Bains ¹ , Si Jian Hui ² , Veushj Sharma ³ , Niten Kumar ³ , Laranya Kumar ⁴ , Nirmal Singh ¹ , Amarjit Rai ⁵ , Naresh Kumar ²

¹ Northern California Regional Spine Center, Oakland, United States,

² National University Health System, Singapore, Singapore,

³ SGL Hospital, Amritsar, India,

⁴ Royal College of Surgeons of Ireland, Dulin, Ireland,

⁵ London Norwich Spine Clinic, Norwich, United Kingdom

Background: The aim of our study is to establish whether the bone graft harvested and stored in the surgical wound by our novel technique is safe, reproducible and preserves the viability of the graft. In doing so, it promises successful bony fusion in spine and orthopaedic surgeries. Material and Methods: A prospective clinical case series was conducted for autogenous bone graft storage in complex spine surgeries requiring staged procedures, in resource constrained settings. The bone graft harvested was morselized, wrapped in moist sterile gauze and stored in the paraspinal gutter within the operative site. Thereafter, the surgical wound was easily closed without tension. During the second stage surgery, the stored bone was retrieved and mixed with more autologous bone (if necessary) and appropriately laid at fusion sites. Bacterial samples were sent before implantation. Results: 16 complex spinal deformity patients who underwent surgery in a resource constrained hospital over a period of 5 years were included. Duration between both stages was within 2 weeks. All patients showed successful fusion, with mean follow-up of 2.6 years. There were no cases of deep or systemic infection in our series. Surgeons found harvesting, storing and retrieval of graft to be straightforward. Conclusion: The operative site provides an ideal, safe and reproducible location for bone graft storage for staged surgeries conducted in resource constrained situations. The osteogenic potential of the autogenous bone graft is retained. This technique can be extrapolated to other orthopaedic surgeries conducted under resource limited environments like in surgical camps or combat medical facilities.

Keywords: Autologous bone graft, Auto-bone bank, Storage, Resource-constrained, Staged Spine Surgeries

Level of evidence III

ID: 270

RF159: Comparison of rostral facet joint violations in robotic- and navigation-assisted pedicle screw placement for adult lumbar spine instrumentation

Paal Nilssen ¹ , Nakul Narendran ¹ , David Skaggs ¹ , Alexander Tuchman ² , Corey Walker ² , Tiffany Perry ² , Christopher Mikhail ¹

¹ Cedars-Sinai Medical Center, Orthopaedic Surgery, Los Angeles, United States, ² Cedars-Sinai Medical Center, Neurosurgery, Los Angeles, United States

Introduction: Facet joint violation by pedicle screws may lead to adjacent-segment disease and postoperative pain. Previous studies have reported the incidence of rostral facet joint violation using various pedicle screw insertion techniques. However, the incidence of facet joint violations with robotic guidance has not been determined. Materials and Methods: All patients who underwent robotic-assisted lumbar fusion at a major spine center up until 2023 were retrospectively identified and matched 1:3 to patients undergoing CT navigation guidance based by on age, sex, rostral vertebral level, and length of construct. Inclusion criteria consisted of age greater than 18 years, bilateral pedicle screw fixation, and presence of a postoperative CT scan of the lumbar spine or abdomen/pelvis at any point in the post-operative period. Descriptive statistics were used to compare cohorts: frequencies, chi-squared analysis for categorical variables, and t-test for continuous variables. Results: A total of 408 rostral pedicle screws were implanted in 204 patients (Robot: 102; Navigation: 306). Overall, 13 (12.3%) rostral facet joint violations were observed in the robot cohort and 75 (24.5%) in the navigation cohort (p = 0.01). Specifically, fewer robotic violations were observed at the L2 (3.5% vs 32.1%, p = 0.003) and L3 levels (3.9% vs. 18.1%, p = 0.08) compared to navigation. No difference was observed at L4 and L5. Bilateral violations are significantly reduced with robotic approaches (5.3% vs. 14.4%, p = 0.03). Lastly, more facet joint violations were observed during open approaches (robot: 18.8%, navigation: 27.3%) than percutaneous approaches (robot: 11.6%, navigation: 7.1%) in both groups (p < 0.001). The rate of L4 facet violations was 18.8% in the robotic cohort and 27.3% in the navigation cohort. The rate of L5 facet violations was 31.3% in the robotic cohort and 29.2% in the navigation cohort. Conclusion: Use of robotic assistance in lumbar pedicle screws significantly reduced the rate of rostral facet joint violations compared to navigation guidance at L2 and L3 levels, but not at L4 and L5, with facet violations approaching nearly one-third of the patients at L5 screws. Rostral facet violations can play a significant role in adjacent segment degeneration and disease. Technical factors and trajectory issues likely play a role and addressing these components should minimize unintended facet violation and proximal adding on.

ID: 2098

RF160: Augmented reality enhanced tubular trans-facet interbody fusion: a multi-surgeon 32 case series

Jose Castillo ¹ , Hania Shazad ¹ , Safdar Khan ¹ , Richard Price ¹

¹ University of California Davis, Sacramento, United States

Introduction: Augmented reality (AR) utilizes optical images that are projected into the user’s field of view to create a visual overlay in the visual field. Recently, augmented reality technology has been applied to spine surgery to assist in navigating pedicle screws. Moreover, the technology can be expanded to additional aspects of spine surgery such as tubular transforaminal interbody fusion (MIS TLIF). Here we show novel applications of AR to perform the entirety of a MIS TLIF (AR-MIS TLIF) from a two surgeon case series. The addition of AR ultimately improves efficiency and reduces radiation exposure for surgical teams. Material and Methods: A retrospective review of 32 consecutive patients undergoing 1 or 2 level MIS-TLIF from two different surgeons was conducted. In this series AR (Augmedics xvision) was utilized for the entirety of the procedure, not just for screw navigation. Briefly, an intra-operative CT was performed and the data loaded into xvision console for processing. The surgeon and assistant were fitted with xvision head-mounted display. From this point AR navigation was utilized for the entirety of the tubular MIS-TLIF procedure. AR was used for pedicle screw placement, decortication of contralateral facets, placement of graft materials, facetectomy, and discectomy portions of the MIS TLIF were examined. Intra-operative CT or Xrays were used to confirm accurate placement pedicle screws and interbodies. Intra-operative data and complication data was analyzed. Results: AR-MIS TLIF was performed on 32 patients with a total of 42 TLIF levels. All patients have at least a six week follow up. Average operative time was 124 minutes per level. Blood loss averaged 60.4 ml per operation, or 47.9 ml per level fused. All 24 patients were ambulatory on POD 1. Fourteen patients (43.8%) were discharged on POD 1 and seventeen patients (53.1%) were discharged on POD 2 and one patient on POD 4 (3.1%). No patients experienced major surgical complications. There was a significant reduction (p < 0.01) in fluoroscopy time with AR-MIS TLIF when compared to traditional MIS TLIF. All pedicle screws (n = 162) and interbodies (n = 42) were accurately positioned as verified by post-operative Xrays. There was a significant reduction (p < 0.01) in fluoroscopy time with AR-MIS TLIF when compared to traditional transfacet MIS-TLIF. Conclusion: The use of AR allows for an efficient and precise MIS TLIF that is reproducible among surgeons. In this series, screw accuracy and interbody was 100%. There also were no complications related to instrumentation. We show that AR navigation can be implemented beyond pedicle screw placement to perform most surgical steps through the entirety of an MIS-TLIF. Augmented reality allows for precision in establishing trajectory into the disc space as well as within the disc space to plan interbody placement. This allows for faster, more precise surgery while also significantly reducing radiation exposure. This study demonstrates the power of applying AR to the entirety of spine surgery procedures, not just pedicle screw placement.

RF10: DEGENERATIVE SPINE SURGERY

ID: 702

RF161: Best frailty index in thoracolumbar deformity surgery and risk factors associated with complications

Esteban Quiceno Restrepo ¹ , Shashwat Shah ² , Mohamed Soliman ¹ , Isabelle Stockman ² , Benard Okai ² , Hendrick Francois ² , Deanna Chan ² , Joseph St. Onge ² , Jacob Greisman ¹ , Asham Khan ¹ , Charles Stube ² , Ryan Goliber ² , Ethan Herbold ² , Benjamin Ciocca ² , Maxwell Kahn ² , Ethan Kaiser ² , John Pollina ¹ , Jeffrey Mullin ¹

¹ University at Buffalo Neurosurgery, Neurosurgery, Buffalo, United States,

² Jacobs School of Medicine And Biomedical Sciences, Neurosurgery, Buffalo, United States

Introduction: Thoracolumbar adult deformity surgery (ASD) is associated with increased rates of medical and surgical complications. Although several frailty indexes have been described and applied in patient cohorts undergoing complex spine surgery, there is a notable absence of direct comparisons between them. The objective of our study was to determine which is the best frailty index to predict early complications (3 months after surgery) after thoracolumbar spine surgery and determine the factors associated with complications. Material and Methods: Retrospective analysis of consecutive patients from a tertiary center who underwent thoracolumbar ASD surgery involving 7 or more levels, patients were categorized based on the following frailty indexes: mFI-11,mF-5,mF-19,ASD-F1, and CD-F1. Subsequently, patients were further analyzed based on whether they experienced complications or not. Both univariate and regression analyses were performed. Results: A total of 231 patients were included in the analysis. The mean age of the patients was 67.77 ± 12.2 years, and the mean number of levels fused was 9.3 ± 3.2. Frailty scores means were: mFI-11 (0.17 ± 0.14), mF-5 (0.22 ± 0.17), mF-19 (0.13 ± 0.09), ASD-F1 (0.27 ± 0.16), and CD-F1 (0.24 ± 1.32). The best predictor of complications after ASD surgery was CD-F1, with an area under the ROC curve of 0.618. Among the patients, 83 (35.9%) experienced complications. Those who experienced complications had longer fusions (10 ± 3.6vs8.87 ± 2.9 levels, p = 0.008). Additionally, their mF-5, mF-19, ASD-F1, and CD-F1 scores were significantly higher compared to those without complications (p < 0.05). Patients reporting feeling worn out most of the time (p = 0.009), having poor general health (p = 0.032), not being in excellent health (p = 0.004), or having an unsteady gait (p = 0.024) were more likely to experience complications in the univariate analysis. In the regression analysis, factors associated with complications included age above 80 years old (OR4.8,95%CI1.33-17.465, p = 0.016) and diabetes (OR3.73,95%CI1.38-10.1, p = 0.009). Conclusion: The best available frailty score to determine complications after thoracolumbar ASD surgery is CD-F1, additionally, patients aged above 80 years old and those with diabetes have higher odds of experiencing complications following ASD surgery.

ID: 1456

RF162: Reintervention for adjacent segment disease in a cohort of patients operated of anterior corpectomy and fusion for degenerative cervical myelopathy

Michele Da Broi ¹ , Aria Nouri ¹ , Granit Molliqaj ¹ , Karl Schaller ^1,2 , Enrico Tessitore ^1,2

¹ Geneva University Hospitals, Neurosurgery, Geneva, Switzerland,

² University of Geneva, Medecine, Geneva, Switzerland

Introduction: To analyze reoperation rate with specific focus on adjacent segment disease (ASD) in a cohort of patients operated of anterior corpectomy and fusion (ACCF) for degenerative cervical myelopathy (DCM). Material and Methods: A prospectively collected database of 34 consecutive patients who underwent ACCF for DCM at Geneva University Hospital between 2019 and 2023 were analyzed regarding reintervention rate and postoperative complications. Results: Overall, 79.4% patients (27/34) underwent ACCF as first surgery, while 20.6% as revision. A PEEK cage was used in 14 cases (41.2%), and a titanium in 20 cases (58.8%). The mean preoperative mJOA was 13.4 ± 2.6 with a mean increase of 1.4 ± 2.5 at 1 year follow-up. The reoperation rate was 17.6% (6/34) with a mean time to second surgery of 228.7 ± 245.0 days over a mean follow-up of 18 ± 11.2 months. Median age at first surgery was 61.0 years [range: 52.5-69.5 years]. The main reason for reintervention was hardware loosening (11.8%, 4/34), only 1 patient (2.9%) for ASD, and 1 for persistent stenosis (2.9%). Altogether, 34 patients underwent 50 surgical procedures with a postoperative hematoma rate of 4.0% (2/50), and postoperative infection rate of 2.0% (1/50). Discussion: ACCF seems to be a safe and effective technique to treat patients with DCM with a low infection and postoperative hematoma rate. ASD seems to be a rare cause of reintervention in patients who undergo ACCF.

ID: 689

RF163: The effectiveness of artificial intelligence-based pedicle screw trajectory planning in patients with different levels of bone mineral density

Xu Xiong ^1,2 , Jiaming Liu ^1,2 , Shanhu Huang ^1,2 , Zhi-Li Liu ^1,2

¹ The First Affiliated Hospital, Jiangxi Medical College, Nanchang University, Department of Orthopaedic Surgery, Nanchang, China,

² Jiangxi Provincial Key Laboratory of Spine and Spinal Cord Disease, Nanchang, China

Introduction: Pedicle screw fixation is the predominant method used for providing spinal stability in lumbar spine surgery. However, one of the major challenges associated with this technique is the potential loosening of pedicle screws, particularly in patients with osteopenia and osteoporosis. Therefore, increasing the pullout force (POF) of pedicle screws in patients with osteopenia and osteoporosis is helpful to reduce the incidence of screw loosening. AO standard screw trajectories may coincide with regions of low vertebral bone mineral density (BMD) and result in screw loosening due to low screw POF. Despite growing literature exploring the utilization of artificial intelligence (AI)in pedicle screw trajectory planning, there is still a paucity of studies on the investigation of its efficacy in patients with different levels of BMD. In this study, a novel AI software was utilized to plan pedicle screw sizes and trajectories. The objective of this study was to investigate the effectiveness of AI-based pedicle screw trajectory planning in patients with different levels of BMD by comparing it with the AO standard screw trajectory. Material and Methods: The patients were divided into five groups (group A-E) according to their BMD. The AI software utilizes lumbar spine CT data to perform screw trajectory planning and simulate AO screw trajectories for bilateral L3-5 vertebral bodies. Both screw trajectories were subdivided into unicortical and bicortical modes. The AI software automatically calculating the POF and pullout risk of every screw trajectory. The POF and risk of screw pullout for AI-planned screw trajectories and AO standard trajectories were compared and analyzed. Results: Forty-three patients were included. For the screw sizes, AI planned screws were greater in diameter and length than those of AO screws (p < 0.05). In groups B-E, the AI unicortical trajectories had a POF of over 200N higher than that of AO unicortical trajectories. POF was higher in all groups for the AI bicortical screw trajectories compared to the AO bicortical screw trajectories (p < 0.05). AI unicortical trajectories in groups B-E had a lower risk of screw pullout compared with that of AO unicortical trajectories (p < 0.05). Conclusion: AI unicortical screw trajectory planning for lumbar surgery in patients with BMD of 40–120 mg/cm3 can significantly improve screw POF and reduce the risk of screw pullout.

Keywords: bone mineral density; pedicle screw; pullout force; osteoporosis; artificial intelligence

ID: 2244

RF164: Measuring surgical outcomes of delayed presented cauda equina syndrome patients using a new scoring system: analysis of 109 patients

Sarvdeep Dhatt ¹

¹ PGIMER, Orthopaedics, Chandigarh, India

Study Design: Retrospective Cohort Study. Objectives: To evaluate the long-term outcomes of cauda equina syndrome patients who presented delayed in their course of disease. To develop a scoring system to evaluate long-term surgical outcomes of cauda equina patients. To determine the predictors of good and poor functional outcomes. Setting: PGIMER, Chandigarh, India Methods: All patients who completed 2 years after their surgery were called and examined to see motor, sensory and autonomic dysfunction. ODI (Oswestry Disability Index) scores were measured. Patients were divided into 3 groups i.e, Good, Fair and Poor outcome groups at 2-year follow-up based on a new scoring system i.e, Dhatt & Kumar scoring. This scoring system was compared with ODI score to check its sensitivity and specificity. Results: 109 patients included in this study with mean age of 42.8 yrs (21 . 66), mean follow-up duration 7.2 ± 2.6 years, and mean delay was 14.50 ± 9.7 days. All patients showed improvement in atleast few parameters. ODI scores in patients with good, fair and poor outcomes were 2.7 ± 1.26, 7.65 ± 3.05 and 16.17 ± 1.17 respectively. Young patients, male sex, positive anal wink at presentation determine good outcome. Diabetic patients are prone to have poor outcomes. Conclusion: Age, past history of sciatica, diabetes, anal wink are the predictors of surgical outcomes. Dhatt & Kumar scoring system is useful in evaluating functional outcomes of cauda equina patients.

ID: 2031

RF165: Effect of positional graft placement on pseudarthrosis rates in anterior cervical discectomy and fusion

Soroush Shabani ¹ , Brandon Yoshida ¹ , Andy Ton ² , Ivan Luu ¹ , William Karakash ¹ , Emily Mills ¹ , Jeffrey C. Wang ¹ , Raymond Hah ¹ , Ram Alluri ¹

¹ Keck School of Medicine of USC, Department of Orthopaedic Surgery, Los Angeles, United States,

² UCI School of Medicine, Department of Orthopaedic Surgery, Irvine, United States

Introduction: Anterior cervical discectomy and fusion (ACDF) is the most common surgical treatment for cervical degenerative conditions. The procedure involves placement of an interbody graft, which may be paired with anterior plate fixation. A common postoperative complication is fusion degradation, which can progress to pseudarthrosis through hardware loosening and subsequent intersegmental motion. This study aims to investigate the potential association between location of graft placement along the vertebral body and pseudarthrosis occurrence. Material and Methods: This was a retrospective cohort analysis analyzing consecutive patients at a single academic hospital undergoing ACDF from 2020-2024. Pseudoarthrosis status was determined using a dynamic mobility criterion. The criterion employed ≥ 4 mm superjacent interspinous motion to validate functional cervical mobility and ≥ 1 mm interspinous movement to indicate pseudarthrosis. Graft length and vertebral body length were measured at 150% magnification on the most recent radiograph after time of surgery. Graft location was categorized as either anterior or posterior placement if its midpoint was positioned within the anterior 50% or posterior 50% of the endplate length respectively. These measurements were calibrated to the flexion and extension radiographs. Flexion and extension spinous movements were measured at 150% magnification on radiographs taken closest to the 2 year post operative mark, within a window of 6 months to 2 years after surgery. T1 slope, cervical lordosis angle, and sagittal vertical axis length were also measured in neutral position on the flexion and extension radiographs. All measurements were conducted by a single independent investigator. A univariate logistic regression was used to analyze the data. Results: This retrospective analysis encompassed 106 patients (57 male) who underwent single and multi-level ACDF, resulting in a total of 180 individual levels analyzed. Among these levels, 120 (66.6%) demonstrated fusion, while 60 (33.3%) met radiographic criteria for pseudarthrosis. Statistical analysis revealed no significant association between pseudoarthrosis and the following parameters: graft to endplate ratio, posterior graft space, anterior graft space, and the respective normalized percentages as a ratio to the endplate (p > 0.05). Graft location approached significance (p = 0.09, OR = 0.87). 134 grafts were placed posteriorly, and the remaining 46 were anterior. The mean posterior graft space for successful fusion was 3.50 mm and in the pseudarthrosis cohort 3.11 mm (p > 0.05). The mean anterior graft space for successful fusion was 0.94 mm and in the pseudarthrosis cohort 0.80 mm (p > 0.05). The mean graft to endplate ratio for successful fusion was 0.78%, while in pseudarthrosis cohort it was 0.80% (p > 0.05). Conclusion: The findings of this study suggest that graft placement does not significantly influence the likelihood of pseudarthrosis development following ACDF, despite graft location approaching significance. Additional studies are warranted to determine the impact of graft placement on pseudarthrosis. These results currently support the surgeon's discretion in positioning grafts to optimize fusion and clinical outcomes.

ID: 945

RF166: The effect of varenicline use on clinical and patient-reported outcomes in smokers undergoing spinal fusion

Goutham Yalla ¹ , Rachel Huang ¹ , Tariq Issa ² , Siddharth Vemuri ¹ , Saket Gokhale ¹ , Hannah Levy ³ , Jose Canseco ¹ , Alan Hilibrand ¹ , Gregory Schroeder ¹ , Alex Vaccaro ¹ , Christopher Kepler ¹ , Brian Karamian ⁴

¹ Department of Orthopaedic Surgery, Rothman Orthopaedic Institute at Thomas Jefferson University, Philadelphia, United States,

² Department of Orthopaedic Surgery, Icahn School of Medicine, The Mount Sinai Hospital, New York, United States,

³ Department of Orthopedic Surgery, Mayo Clinic, Rochester, United States,

⁴ Department of Orthopaedic Surgery, University of Utah, Salt Lake City, United States

Introduction: Smoking is a known inhibitor of spinal fusion, with high serum nicotine levels shown to significantly increase pseudoarthrosis. Varenicline, a pharmaceutical adjunct for smoking cessation, is a partial agonist that outcompetes nicotine at the α4β2 acetylcholine receptor. Animal models have shown varenicline to mitigate nicotine’s adverse effects on spinal fusion, but there is a lack of clinical studies examining this relationship. Therefore, this study aims to determine the effect of varenicline use on clinical and patient-reported outcomes after spinal fusion, when compared to current smokers. Material and Methods: Patients > 18 years of age who underwent primary 1- to 4- level anterior cervical discectomy and fusion (ACDF) or primary 1- to 3- level lumbar fusion (posterior lumbar decompression and fusion [PLDF] or transforaminal lumbar interbody fusion [TLIF]) at a single institution from 2014 to 2022 were retrospectively identified. Current smokers or patients taking varenicline in the perioperative period (documented prescriptions within 14-days of surgery) were included and divided accordingly into two cohorts. Patient demographics, surgical characteristics, and surgical outcomes were collected. Patient-reported outcome measures (PROMs) extracted at 3-months, 6-months, 1-year, and 2-years included VAS (Neck/Arm for ACDF, Back/Leg for lumbar fusion), Neck Disability Index (NDI), Oswestry Disability Index (ODI), and the Mental and Physical Components of the Short-Form 12 Health Survey (MCS-12 and PCS-12, respectively). For ACDF patients, postoperative flexion-extension radiographs evaluated radiographic fusion, defined as < l mm of interspinous motion between each instrumented level as per Cervical Spine Research Society Special Project Committee guidelines. ≥ l mm of motion defined pseudoarthrosis. Statistical significance was set at p < 0.05. Results: 554 patients were included. 143 (25.8%) were on varenicline during the perioperative period and 411 (74.2%) were current smokers. Smoking status at 1-year (p = 0.362) and 2-year (p = 0.283) were not statistically significant between cohorts. Revision rates were lower in varenicline patients (varenicline: 4.20% vs. smoker: 9.61%, OR = 0.42 [0.16-0.95], p = 0.064) with a statistically significant odds ratio, but an insignificant p-value. Differences in 90-day readmission (varenicline: 1.40% vs. smoker: 3.91%, p = 0.179) and secondary adjacent segment procedures (varenicline: 6.99% vs. smoker: 5.91%, p = 0.795) were not statistically significant. Among 211 ACDF patients (77 on varenicline [36.5%], 134 smokers [63.5%]), revision rates were not different (varenicline: 3.90% vs. smoker: 9.09%, p = 0.260). There were no differences in radiographic non-union (varenicline: 36.4% vs. smoker: 40.0%, p = 0.897). Changes in PROMs were insignificant apart from delta 1-year PCS (varenicline: -6.31 vs. smoker: 4.23, p = 0.024) and delta 1-year VAS Arm (varenicline: -0.57 vs. smoker: -3.23, p = 0.044). Among 343 lumbar fusion patients (66 on varenicline [19.2%], 277 smokers [80.8%]), revision rates were not different (varenicline: 4.55% vs. smoker: 9.85%, p = 0.261). Changes in PROMs were insignificant apart from delta 3-month ODI (varenicline: -8.10 vs smoker: -20.15, p = 0.013). Conclusion: Perioperative varenicline use may reduce revision rates following spinal fusion when compared to current smokers. Isolating cervical and lumbar fusion patients showed minimal differences between cohorts, including radiographic fusion in ACDF patients. Analysis demonstrates no adverse clinical outcomes associated with varenicline use in the perioperative period, but without definitive benefits on spinal fusion outcomes.

ID: 757

RF167: Adjacent level disease following posterior cervical decompression and fusion

Morsi Khashan ¹ , Dror Ofir ¹ , Zvi Lidar ¹ , Gilad Regev ¹ , Khalil Salame ¹

¹ Tel Aviv Medical Center, Tel Aviv University, Tel aviv, Israel

Introduction: Adjacent segment disease (ASD) is a frequent and extensively investigated complication following anterior cervical fusion surgery, ranging from asymptomatic adjacent segment degeneration (ASDeg) to symptomatic ASD. However, data on ASD following Posterior Cervical Fusion is scant. This study aims to investigate the occurrence and risk factors of ASD in patients post posterior cervical fusion surgery. Methods: This is an observational cohort study in which we retrospectively analyzed the clinical data from patients who underwent primary posterior cervical fusion. We included patients with at least two year follow up. The collected data included patient demographics, comorbidities, results of neurological examinations conducted before and after surgery, and post-operative complications. Radiographic measurements included the C2-C7 Cobb angle, T1 slope, and C2-C7 lordosis using sagittal view MRI or CT images. Results: Eighty four patients met the inclusion criteria. ASD was diagnosed in eleven patients (13%), and three of which underwent reoperation due to ASD. Multivariate analysis revealed a higher incidence of ASDeg in patients with non-lordotic preoperative curves (p = 0.03, Odds ratio = 3.385, 95% confidence interval 1.14-10.02), though this wasn't the case for ASD. Additionally, patients who faced post-operative complications developed ASD at an accelerated rate (OR = 5.04, CI 1.07-23.68, p = 0.04). Conclusions: Our study revealed a more frequent occurrence of adjacent segment disease compared to previous studies. Risk factors for ASD included loss of effective preoperative lordosis and complications following surgery.

ID: 768

RF168: A comparison of radiological and functional outcomes of anterior cervical discectomy and fusion using standalone polyetherether-ketone cages: fin anchored cage vs screw anchored cage designs

Cassie Yang ¹ , Yeong Huei Ng ¹ , Reuben Soh ¹ , John Chen ¹ , Youheng Ou Yang ¹

¹ Singapore General Hospital, Department of Orthopaedic Surgery, Singapore, Singapore

Introduction: Standalone Polyetherether-Ketone (PEEK) cages for anterior cervical fusion may be anchored by either broad stabilising fins, or by a combination of fixed angle screws. These anchoring options violate the adjacent bony endplates differently. We hypothesize that this may lead to potential differences in radiological or functional outcomes. This study evaluates the 1-year radiological and 2-year functional outcomes of patients undergoing anterior cervical discectomy and fusion (ACDF) with Finned Anchored Cages (FAC) and Screw Anchored Cages (SAC). Material and Methods: A retrospective review of patients who underwent a single or double level ACDF for a diagnosis of cervical myelopathy, radiculopathy or myeloradiculopathy, with either FAC or SAC between 2015 and 2022 at a single tertiary institution. Patients with prior cervical spinal surgery, additional cervical procedures within 1 year, a diagnosis of malignancy, trauma, or infection were excluded. Data was collected for: patient age, gender and number of levels operated. Radiological outcomes were quantified by subsidence rate (>2mm change in total intervertebral height), fusion rate, Δ Sagittal Cobb Angle after surgery (ΔSCA) at 1 year. Functional outcomes were quantified by the American Association of Orthopaedic Surgeons (AAOS) Neck Pain and Disability (NPD), Neurogenic Symptoms (NS), Neck Disability Index (NDI), SF-36, Visual Analog Scale (VAS) for Neck and Upper Limb Pain, Japanese Orthopaedic Association Cervical Myelopathy Score (JOA-CMS) at 6 months and 2 years. Results: 37 FAC and 42 SAC cases were identified. The average age of patients were 64.5 ± 10.4 years old for FAC and 56.5 ± 10.6 for SAC. There were no significant differences in the number of levels operated, 1 level (FAC = 19, SAC = 20), 2 level (FAC = 18, SAC = 22) and gender distribution (FAC = 19 M, 18 F, SAC = 26 M,16 F) (p > 0.05). Subsidence rates were significantly higher in FAC (FAC = 54.1%, SAC = 28.6%, p = 0.012). There was no change in fusion rate (FAC = 86.5%, SAC = 95.2%), ΔSCA (FAC = -4.84°, SAC = 3.16°) (p > 0.05) at 1 year. At 6 months, NDI (FAC = 11.6, SAC = 18.3 p = 0.049) and VAS Upper Limb Pain (FAC = 0.47, SAC 1.68 p = 0.037) were superior in FAC. NPD, NS, NDI, SF-36, VAS neck pain and JOA-CMS were not significantly different (p > 0.05). At 2 years, all measured PROMS: NPD, NS, NDI, SF-36, VAS Neck Pain, VAS Upper Limb Pain, JOA-CMS did not reach statistical significance between the two groups (p > 0.05) Conclusion: Compared to SAC, FAC cages demonstrated nearly double the subsidence rates at 1 year. However, FAC cages conferred earlier functional improvements in 6-month NDI and VAS Upper Limb Pain scores. Nonetheless, at 2 years, both designs demonstrated no significant difference in all measured functional outcomes. Therefore, neither FAC or SAC cage designs offer a clear clinical advantage over the other in terms of long-term functional and radiological outcomes.

ID: 1764

RF169: Improvement in clinical mobility after single level lumbar fusion surgery

Rabie Ayari ¹ , Achref Abdennadher ¹ , Khalil Amri ¹ , Manai Mohamed ¹ , Khaled Khlil0 ¹

¹ Military Hospital of Tunis, Tunis, Tunisia

Introduction: Lumbar fusion surgery prevents mobility on the operated levels, which is a source of concern for patients. However, fusions are generally performed on pathological levels with limited mobility. Furthermore, the pain generated by the pathology tends to limit overall lumbar mobility. Thus, arthrodesis would not necessarily limit mobility, and might even restore it by relieving the symptoms. The aim of this study was to analyze spinal mobility by evaluating finger to ground distance (FGD) before and after single-level lumbar fusion surgery, regardless of the technique or the level. Material and Method: All patients operated on for single-level lumbar arthrodesis surgery between 01/01/2018 and 01/08/2023 were included in this study. For all patients, in addition to standard data and information on the type of surgery, flexion mobility by finger to ground distance was measured by a computer tool during a physiotherapy check-up pre-operatively, at 3 months and at one year follow-up. Results: 195 patients were analyzed. All patients were operated on using the posterior approach with cage (TLIF). Patients suffered from different pathologies (disc disease, degenerative spondylolisthesis lysis spondylolisthesis). One year after fusion, 102 patients (52%) improved their mobility, with a mean gain of 15.6 cm, p < 0.001. It should be noted that all patients had good results at one year: on satisfaction (87% of patients satisfied or very satisfied), on pain (3.3-point decrease in lumbar VAS) and on function (30-point decrease in Oswestry score). Conclusion: In spinal pathologies where medical treatment has failed, single-level lumbar fusion does not reduce lumbar mobility, and even appears to significantly improve it. This analysis simply serves to reassure patients about their concerns about loss of mobility in case of lumbar arthrodesis surgery.

ID: 2740

RF170: Complications and revision strategies in multilevel anterior cervical discectomy and fusion with stand alone cages

Senol Jadik ¹

¹ Kuwait Hospital, Neurosurgery, Kuwait City, Kuwait

Introduction: Anterior cervical discectomy and fusion (ACDF) is a common surgical procedure used to address cervical spine pathologies, particularly in cases involving radiculopathy or myelopathy. However, there is a growing body of evidence suggesting potential complications associated with standalone cages in multilevel ACDF, especially among elderly patients. This study aims to examine the outcomes of ACDF using standalone cages, with a particular focus on vertebral body collapse, kyphotic deformities, and other post-surgical complications. Materials and Methods: A retrospective analysis was conducted on 100 patients who underwent multilevel ACDF using standalone cages. Patient demographics, clinical presentations, and postoperative outcomes were collected and analyzed. Radiological assessments and follow-up evaluations were performed to assess vertebral stability, deformity progression, and any need for revision surgeries. Additionally, cases with atypical symptoms such as nonfusion, facet joint arthropathy, and persistent neck pain were evaluated with bone scintigraphy and managed accordingly. Results: Out of 100 patients, 8 experienced significant vertebral body collapse post-ACDF, leading to kyphotic deformities that required revision surgeries involving corpectomy and anterior plating. These patients initially presented with mild radiculopathy and neck pain, which progressively worsened into severe cord compression manifesting as gait imbalance, electric sensations, limb stiffness, and myelopathy. Furthermore, 5 patients developed nonfusion, facet joint arthropathy, and persistent neck pain, with bone scintigraphy showing increased enhancement in facet joints. Anterior revision with plates and cages or posterior fixation was performed to address these issues. Conclusion: The findings highlight the potential for adverse outcomes, such as vertebral body collapse and kyphotic deformities, following multilevel ACDF with standalone cages in elderly patients. These complications can progress to severe neurological impairment and require complex surgical revisions. The study underscores the need for careful preoperative planning, intraoperative decision-making, and vigilant postoperative monitoring, particularly in elderly patients undergoing ACDF with anterior plating. In cases with persistent or atypical symptoms, additional diagnostic tools and surgical approaches, such as anterior plating or posterior fixation, may be necessary to manage complications effectively.

ID: 1056

RF171: Comparison between UNI-TLIF and Standard TLIF on sagittal lumbar-pelvic parameters for degenerative lumbar diseases and its relation with patient reported outcomes

Kunal Chanji ¹ , Sajan Hegde ¹ , Appaji Krishnan ¹ , Vignesh Badikillaya ¹ , Harith Reddy ¹ , Sharan Achar Thala ¹ , Akshya Raj ¹ , Sakthivel Ramaswamy ¹

¹ Apollo Hospitals, Spine Surgery, Chennai, India

Introduction: Improving the sagittal lumbar-pelvic parameters after fusion surgery is important for improving clinical outcomes. Lumbar degenerative disorders, including lumbar spinal stenosis, lumbar disc herniation, and degenerative lumbar spondylolisthesis, can be effectively treated with transforaminal lumbar interbody fusion surgery (TLIF). A lengthy recovery period, higher intraoperative bleeding and postoperative complications, and significant paraspinal muscle dissection are some of the few problems with the standard open TLIF surgery. Using the novel technique of UNI-TLIF in which via unilateral exposure with unilateral pedicle screw insertion and direct decompression on the affected side with indirect decompression on the opposite side is achieved. This minimizes the surgical incision and decreases muscle insult, which ultimately results in less trauma and bleeding. To our knowledge no study has studied the use of the novel technique of UNI-TLIF in restoration of sagittal lumbar pelvic parameters. The sagittal lumbar pelvic alignment is restored using a long modular banana cage inserted from the open side. The current study compared the imaging data and clinical efficacy of UNI-TLIF with those of standard TLIF to evaluate the impact of both procedures on the sagittal lumbar-pelvic parameters in the treatment of lumbar degenerative diseases. Material and Methods: Patients who underwent single-segment UNI-TLIF and standard TLIF for lower back pain, unilateral or bilateral lower-limb radiating pain, numbness, or intermittent claudication after strict conservative treatments for at least three months with complete preoperative and postoperative lateral lumbar X-ray images and at least two year of follow-up data after surgery were included. Results: In our study, in the UNI-TLIF and standard TLIF groups showed significant improvement in LL at the final follow-up. Moreover, statistical analysis showed that there was no significant difference in ΔLL within the two groups. Therefore, it must be considered that UNI-TLIF and standard TLIF have an equal ability to improve LL in the treatment of lumbar degenerative diseases. Results revealed, PI was similar to that recorded prior to operation, while SS significantly increased and PT significantly decreased compared to those recorded prior to operation in both groups confirming that UNI-TLIF could achieve similar results as compared to Standard TLIF. Clinically, both groups' patients had better VAS and ODI scores at the final follow-up than when they were recorded before the procedure. There was no significant difference in clinical patient reported scores between the two groups at the final follow-up. Conclusion: One-level unilateral pedicle screw instrumented UNI-TLIF provided similar sagittal parameters and clinical outcomes to bilateral pedicle screw instrumented standard TLIF with the added benefit of less operative time, less blood loss, shorter hospitalization, and less cost in selective cases. This study showed that UNI-TLIF with unilateral pedicle screw fixation should be sufficient in the management of preoperatively stable patients with lumbar degenerative disease.

ID: 564

RF172: Historical evolution, management, and outcome of surgical treatment of high grade spondylolisthesis: a systematic review

Elias Elias ¹ , Daoud Ali ² , Elias Charbel ³ , Ryan Chiu ¹ , Jose Sanchez ¹ , Zeina Nasser ⁴

¹ University of Texas Southwestern, Dallas, United States,

² Illinois College, Jacksonville, United States,

³ University of Pittsburgh, Thomas E. Starzl Transplantation Institute, Pittsburgh, United States,

⁴ Lebanese University, Faculty of Medicine, Beirut, Lebanon

Background and Objectives: High-grade spondylolisthesis (HGSL) is a rare condition characterized by a vertebral slippage of more than 50% relative to the adjacent vertebra. Despite the range of surgical techniques available, there is no consensus regarding the optimal management approach for HGSL. Although various interventions are documented in the literature, definitive guidelines remain absent. Our systematic review aims to provide a comprehensive analysis of the chronological evolution of surgical management, along with clinical, and radiographic outcomes and complications, to assist surgeons in selecting the best techniques for their patients. Methods: PubMed, Ovid Medline, Cochrane, Cumulative Index to Nursing and Allied Health Literature (CINAHL), and Scopus were systematically searched for eligible studies published in peer-reviewed journals up till May 2024. Following data extraction, the National Institutes of Health (NIH) quality assessment tools were used to evaluate the methodological quality of the included studies. Results: Out of 1798 papers found in the literature, 33 met the inclusion criteria. Eligible articles assessed 463 subjects with HGSL. Fifteen papers described the reduction approach whereas nineteen papers described the In-Situ fusion technique. Most of the reported neurological injuries were associated with reduction techniques, whereas most of the graft failures were associated with Bohlman’s technique. Most patients in both In-Situ fusion and decompression and fusion reported good outcomes post-operatively in terms of back pain and leg pain. Conclusion: The historical progression of HGSL treatment, from its early interventions in 1932 to the techniques used today, has been pivotal in shaping patient outcomes. Our findings have many implications for clinical practice and provide a framework for implementing treatment guidelines. The authors underscore the importance of a comprehensive evaluation of the benefits and risks of each surgical approach, with particular emphasis on customizing interventions to accommodate the specific anatomical features of each patient.

Keywords: Systematic review; High grade Spondylolisthesis; In-Situ fusion; reduction; clinical outcome; complications.

ID: 1035

RF173: Efficacy, safety and reliability of surgery on the lumbar spine under general versus spinal anesthesia analysis of 64 cases

Sharif Ahmed Jonayed ¹

¹ National Institute of Traumatology and Orthopaedic Rehabilitation, NITOR, Spine Surgery, Dhaka, Bangladesh

Study design: Double blinded quasi experimental prospective study. Purpose: The purpose of this study was to compare between GA and SA on patients undergoing lumbar spine surgery in terms of the intra and post-operative parameters, surgeon satisfaction and cost effectiveness. Overview of Literature: Surgery on the lumbar spine is the most common surgical procedure that is encountered among all spinal surgical practices. Both the General anaesthesia (GA) & Spinal anesthesia (SA) are shown to be suitable techniques for performing the surgery safely. Though GA is the most frequently used method, SA is becoming increasingly more popular because it allows the patient to self-position thereby reducing various complications associated with GA in a prone position. Methods: This was double blinded quasi experimental prospective study on 64 patients from June 2016 to July 2019 who underwent either discectomy, laminectomy or lamino-foraminotomy for herniated lumbar disc herniation or lumbar canal stenosis in 1 or 2 levels. They were randomized into two groups with 32 patients in GA Group and another 32 patients were in SA Group. The heart rate (HR), mean arterial pressure (MAP), blood loss, total anesthetic time, surgeons’ satisfaction, analgesic and other medication requirements, cost of the procedure and hospital stay were recorded and compared. Results: There were no significant differences in demographic characteristics, baseline HR, or baseline MAP between the two groups. Mean anaesthetic time, mean PACU time, mean doses of postoperative analgesic and antiemetics requirement and cost of anesthesia was significantly less in SA Group in comparison with GA group (p < 0.05). But, the amount of blood loss, duration of operation and hospital stay though varied between the two groups, no significant difference was observed. Meanwhile, the surgeon’s satisfaction was significantly higher in GA group. No major intra and postoperative complications was reported nor significant difference is found in either series. Conclusion: Spinal anesthesia was as safe and effective as general anesthesia for patients undergoing surgery on lumbar spine. Potential advantages of spinal anesthesia include a shorter anesthesia duration, decreased nausea, antiemetic and analgesic requirements, and fewer complications and relative cost effectiveness. Successful surgery can be performed using either anesthesia type.

Keywords: Lumbar spine surgery, Spinal anesthesia, General anaesthesia

ID: 1523

RF174: Is unilateral pedicle screw fixation and interbody fusion sufficient in treating patients with severe lumbar canal stenosis? A single centre study

Sajan Hegde ¹ , Appaji Krishnan ¹ , Vignesh Badikillaya ¹ , Sharan Achar T ¹ , Akshya Raj ¹ , Sakthivel Ramaswamy ¹

¹ Apollo Hospitals, Greams Road, Thousand Lights, Chennai, India

Introduction: Trans-foraminal Lumbar Interbody Fusion is the standard technique for spinal stenosis. unilateral pedicle screw fixation and interbody fusion is an alternative technique to achieve decompression and fusion in patients with canal stenosis. The advantages of this procedure are less blood loss, less immediate post-op pain, shorter duration of surgery, shorter hospital stay, early recovery and rehabilitation of patient. The use of latest banana/ modular cages with its modular insertion handle and technique aids its positioning in the anterior- middle 1/3^rd of the disc space and inserting the maximum size covering nearly 30-35% of end plate surface. Thus providing the indirect decompression of the canal and opposite neural foraminal area. The aim of this study is to assess the efficacy and benefits unilateral pedicle screw fixation and interbody fusion. Material and Methods: A Total of 245 patients (male 134, female 111) who underwent unilateral pedicle screw fixation and interbody fusion between 2018 to 2022 Were included in this study. Visual analog scale scores and Oswestry disability index, walking distance were assessed at 3 months, 6months, 1year, 2yr post operatively. X-rays and CT scan done to assess fusion, MRI to determine the changes in canal cross sectional area, foraminal height and width restoration. Results: Visual analog scale scores and Oswestry disability index were significantly improved. Mean follow up 30 months (24.40). canal cross sectional area increased significantly from the preoperative 79.7 + 36.02 mm² to 185.8 + 11.3 mm² (p < 0.0001) (2.3 times). The foraminal height and width increased from 12.87 + 3.41 mm, 8.26 + 1.58 mm to 16.43 + 2.32, 9.63 + 1.68 post-operatively respectively (p < 0.005). Conclusion: Unilateral pedicle screw fixation and interbody fusion with ipsilateral side direct decompression and contralateral side indirect decompression is sufficient for significant improvement in patients with lumbar canal stenosis. The improvement of canal cross sectional area, foraminal height and width may be due to increased disc height, indirect distraction by cage.

ID: 2798

RF175: Analysis of adjacent segment degeneration (ASD) and fusion patterns in patients with prior XLIF spinal fusion: a prospective study with a minimum of 36 months follow-up

Riccardo Iundusi ¹ , Amarildo Smakaj ² , Luigi Trupia ¹ , Elena Gasbarra ¹ , Umberto Tarantino ¹

¹ Università di Roma TorVergata, Department of Clinical Sciences and Translational Medicine, Rome, Italy,

² Università di Roma TorVergata, Department of Biomedicine and Prevention, Rome, Italy

Introduction: This prospective single-center study aims to evaluate adjacent segment degeneration (ASD) and fusion patterns in patients who underwent Extreme Lateral Interbody Fusion (XLIF) with posterior instrumentation in the lumbar spine. The focus is on long-term outcomes, with a minimum follow-up of 36 months. Material and Methods: A total of 25 patients (16 women, 9 men) were included in the study, all treated surgically between 2015 and 2021 at the Orthopedics and Traumatology Unit of Policlinico Tor Vergata, Rome. The study population had a mean age of 67.7 ± 10.5 years and a mean BMI of 29.7 ± 4.9 kg/m². The most frequently treated lumbar segments were L4-L5 (46.2%) and L3-L4 (30.8%). All patients underwent XLIF using either titanium or PEEK cages, with posterior fixation using either unilateral or bilateral pedicle screws, or a Facet Wedge device. The mean follow-up period was 79.5 ± 15.8 months, and clinical outcomes were assessed through pre- and post-operative Visual Analog Scale (VAS) and Oswestry Disability Index (ODI) scores. Radiological evaluations focused on fusion patterns and ASD using computed tomography (CT) scans, and disc height was measured at five positions: anterior third, anterior, middle, posterior third, and posterior. Results: The mean pre-operative VAS score was 7.7 ± 1.6, which significantly improved to 3.9 ± 1.8 post-operatively (p < 0.001). The ODI decreased from a pre-operative average of 50.7 ± 16.9 to 31.6 ± 22.6 post-operatively (p < 0.05). Bilateral pedicle screw fixation showed the greatest improvement, with a mean VAS reduction of 6.5 points and an ODI improvement of 42 points. Patients with unilateral pedicle screw fixation showed a VAS reduction of 4.6 points and an ODI improvement of 35.3 points, while the single case with a Facet Wedge showed the least improvement (VAS reduction of 4 points, ODI improvement of 16 points). Radiologically, 100% of patients achieved interbody fusion, with different fusion patterns observed. The most frequent pattern was Type VI (complete fusion within the cage and bone bridging on one side), observed in 38% of patients, followed by Types III and VII (31% each). The Torg-Pavlov index, used to assess spinal canal diameter relative to vertebral body size, improved significantly from 0.32 ± 0.08 pre-operatively to 0.49 ± 0.10 post-operatively (p < 0.001). Disc height reduction was significant across all measured positions. The anterior third showed the greatest reduction (-2.63 mm, p < 0.001), followed by the anterior (-1.78 mm, p < 0.01), middle (-1.61 mm, p < 0.01), posterior third (-1.47 mm, p < 0.01), and posterior (-1.20 mm, p < 0.01). ASD was identified in 15.38% of levels, with greater degeneration observed at inferior adjacent segments (mean reduction -2.30 mm, 23.08% showing a reduction of ≥ 3 mm). Conclusion: This study demonstrates that XLIF with posterior fixation in the lumbar spine, particularly at levels L4-L5 and L3-L4, provides significant clinical improvements in pain and disability, along with high fusion rates. Bilateral pedicle screw fixation offers the best outcomes in terms of pain relief and functional improvement.

ID: 29

RF176: Comparative analysis of minimally invasive transforaminal lumbar interbody fusion outcomes for spondylolisthesis, degenerative disk disease and revision surgery

Stone Sima ¹ , Alisha Sial ^1,2 , Lauren Barber ³ , Charmian Stewart ¹ , Ashish Diwan ^1,2

¹ Spine Labs, St George and Sutherland Clinical School, University of New South Wales, Sydney, Australia,

² Spine Service, Department of Orthopaedics, St George Hospital, Sydney, Australia,

³ Virginia Commonwealth University, Orthopaedics, Richmond, United States

Background: Minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) is growing in acceptance for treating spondylolisthesis but remains unclear for degenerative disk disease (DDD) due to limited comparative studies on these conditions. Though back and leg pain are key symptoms of spondylolisthesis and DDD, they are two different pathologies with different mechanisms of disease. There is a paucity of literature evaluating patient reported outcome measures (PROMs) after MIS-TLIF between spondylolisthesis and DDD. This study aims to compare PROMs between patients undergoing MIS-TLIF for spondylolisthesis and DDD as well as in primary and revision surgeries from a real world surgical setting. Methods: A prospective cohort study of adult patients (> 18 years) who underwent MIS-TLIF between 2020 and 2023 was conducted (n = 80). Comparison between and preoperative and post-operative numerical rating scale (NRS) and Oswestry disability index (ODI) at 3, 6 and 12 months were evaluated. Patients were categorised by diagnosis and primary or revision MIS-TLIF. Results: 80 total patients were included with an average age of 58 ± 14. 41% of the patients were male, 62.5% were diagnosed with spondylolisthesis and 63% underwent primary MIS-TLIF. There was no difference in age and sex between spondylolisthesis vs. DDD group and primary vs. revision group. Both spondylolisthesis and DDD groups experienced significant improvements in back pain NRS, leg pain NRS, and ODI at 3, 6, and 12 months postoperatively (p < 0.001) Patients undergoing primary MIS-TLIF demonstrated improvements in back pain NRS, leg pain NRS, and ODI at all time points post-operatively. However, patients undergoing revision MIS-TLIF demonstrated improvements in back pain NRS at 3 and 6 months, and leg pain NRS at 3, 6 and 12 months, with no changes in ODI post-operatively. Conclusion: Spondylolisthesis and DDD patients all achieved positive outcomes in pain and disability and quality of life following MIS-TLIF. Revision MIS-TLIF patients had a recurrence in back pain at 12 months and did not demonstrate any improvement in disability. These findings demonstrate variations in the efficacy of MIS-TLIF based on different pathologies and surgical context. These results contribute information to guide pre-operative clinical decision making and to manage expectations in patients post-operatively.

ID: 1077

RF177: Pre- and intraoperative factors associated with improvement of neck pain after laminoplasty for the treatment of cervical myelopathy

Dong-Ho Lee ¹ , Chang Ju Hwang ¹ , Jae Hwan Cho ¹ , Sehan Park ¹

¹ Asan Medical Center, Seoul, Souh Korea

Introduction: Laminoplasty offers several advantages in treating cervical myelopathy, including its suitability for long-segment cord compression, preservation of neck motion, and low complication rate. However, the procedure inevitably damages the neck muscles and posterior ligamentous complex of the cervical spine, often resulting in exacerbated neck pain and loss of cervical lordosis. While preservation of muscle insertion at C2 and C7 has been reported as critical for preventing worsened neck pain, other factors predictive of neck pain improvement after laminoplasty remain poorly understood. Therefore, this study aimed to elucidate factors associated with neck pain improvement following laminoplasty. Materials and Methods: We conducted a retrospective review of patients who underwent laminoplasty for degenerative cervical myelopathy. Patients with preoperative neck pain, as measured by the visual analogue scale (VAS) of ≥ 4, and those followed up for ≥ 1 year were included. Patients with a ≥ 50% improvement in neck pain VAS were classified as the improved group, while others were classified as the unimproved group. Radiographic factors including C2-C7 lordosis in neutral, flexion, and extension positions, C2-C7 range of motion (ROM), C2-C7 sagittal vertical axis, T1 slope, K-line tilt, and thoracic kyphosis were measured. Neck pain VAS, Neck Disability Index (NDI), and Japanese Orthopaedic Association (JOA) scores were assessed preoperatively and at the 1-year postoperative follow-up. Regression analysis was performed to identify factors associated with ≥ 50% neck pain improvement. Results: A total of 88 patients were included, with 34 (38.6%) in the unimproved group and 54 (61.4%) in the improved group. Patients in the unimproved group more frequently underwent C3 laminectomy compared to the improved group (76.5% vs. 51.9%, p = 0.026). C2-C7 lordosis in the extension position (improved, 28.2 ± 7.6°; unimproved, 21.9 ± 13.0°; p = 0.006) and C2-C7 ROM (improved, 37.4 ± 11.3°; unimproved, 31.0 ± 17.9°; p = 0.043) were significantly greater in the improved group than the unimproved group. Multivariate logistic regression analysis demonstrated that C3 laminectomy decreased the likelihood of neck pain improvement (odds ratio, 0.285; p = 0.018), while greater C2-C7 lordosis in the extension position increased the possibility of improvement (odds ratio, 1.057; p = 0.048). Cut-off value of 20.5° was with sensitivity of 85.2% and specificity of 47.1% to predict improvement of neck pain after laminoplasty (Area under curve, 0.629; p = 0.043). Conclusion: In this study, 61.4% of patients with moderate preoperative neck pain (VAS ≥ 4) experienced more than a 50% improvement after laminoplasty, suggesting its feasibility for patients with neck pain. Additionally, two factors associated with neck pain improvement were identified: (1) undergoing C3 laminectomy; and (2) greater C2-C7 lordosis in the extension position. Injury to the semispinalis muscles is occasionally inevitable during C3 laminectomy procedures. Previous studies have suggested that preservation of semispinalis cervicis is not possible when the C2 interspinous angle is narrow. Therefore, careful consideration and potential modification of the surgical procedure are warranted when planning C3 laminectomy. Furthermore, greater C2-C7 lordosis in the extension position may indicate better neck muscle power preoperatively, potentially providing greater capacity to resist exacerbation of neck pain after laminoplasty. Thus, patients with greater C2-C7 lordosis in extension, specifically > 20.5°, may be considered good candidates for laminoplasty, even in the presence of preoperative neck pain.

ID: 1574

RF178: Basivertebral nerve ablation as the most effective treatment for discogenic low back pain: prospective case series and feasibility study

Renato Gondar ^1,2 , Frédéric Schils ¹ , Jean-Baptiste Martin ³

¹ Clinique Generale Beaulieu, Neuro and Spine Surgery, Geneva, Switzerland,

² Geneva University Hospitals, Neuro and Spine Surgery, Geneva, Switzerland,

³ Centre Jean Violette, Neuroradiology and Pain Center, Geneva, Switzerland

Introduction: Chronic axial low back pain (CLBP) that is not responsive to medication or physical therapy often requires significant clinical intervention and is a leading cause of disability. Anatomic, histological and clinical evidence demonstrate that vertebral endplates (VEP) have a strong innervation and vascularization via the basivertebral nerve (BVN) and venous plexus, being susceptible to edema, and playing a major role in discogenic/vertebrogenic low back pain. This makes VEP a good target for radiofrequency ablation. While blocking the nociceptive signal transmission of the BVN, this ablation procedure proves to be an effective and durable therapy for the above-mentioned patients, particularly those with either Modic type I or Type II changes (damaged vertebral endplates) between L2 and S1. The objective of our study is to describe the technical feasibility of BVN ablation with straight transpedicular access needles and probes between L1 and S1, as the originally described curved probes are still not available in Europe. We also report on efficacy, safety and expanding indications for this technique. Material and Methods: Twenty-one patients with discogenic CLBP underwent 50 levels of BVN ablation (average 2.4 levels) in a private practice setting between August 2023 and August 2024. Prospective data was collected for Visual analog scale before the procedure and at a last follow-up time (LFU), complication rate and index pathology. Intra-operative imaging was also stored for further anatomical technical description on how to target BVN with the available straight pedicle access needles and probes despite the variable pedicle and vertebral body anatomies. Results: Our cohort included 14 male and 7 female patients with a mean age of 64.3 ± 25 years old. There is a statistically significant improvement in axial low back pain Visual Analogue Scale between the preoperative state (7.4 ± 2.3) and the average LFU (2.3 ± 1.0, p < 0.02). The LFU time until this day is 4.6 ± 2.1 months. Most of our patients presented with Modic I and/or II changes (N = 19, 90.5%) and received BVN ablation as a single procedure. Seven patients (33.3%) benefited from the ablation in combination with, or several months after, microsurgical laminotomy decompression or herniated disc ablation. Conclusion: Previous research showed that BVN ablation is the best treatment for discogenic CLBP in patients exhibiting Modic type 1 or 2 endplate changes but was limited by the lack of independence regarding industry endorsements. Our case series avoids this bias and describes the feasibility of such technique utilizing straight pedicle access needles and probes under 2D fluoroscopy-guidance. Several post-operative MRI imaging proved a good targeting by the lesions made visible, even in the L5 and S1 vertebrae where the anatomy of the pedicles is less favorable. Widespread use and acceptance of this treatment modality is expected to come with the spread of the existing curved devices to other continents and would beneficiate from larger independent studies. Existing literature already shows a significant reduction in healthcare costs and lumbar fusion rates 5 years after BVN ablation compared to baseline. Further indications for BVN ablation could include adjacent segment disease-related pain or even painful pseudoarthrosis.

RF11: SURGICAL COMPLICATIONS IN SPINE SURGERY

ID: 1798

RF179: Spinal infections in conjunction with infective endocarditis: a retrospective analysis and proposal for diagnostic criteria

Artem Ilgeldiev ¹ , Victoria Yushenko ² , Semen Ilgeldiev ³ , Yahya Habib ² , Anne Carolus ² , Veit Braun ²

¹ Diakonie Jung-Stilling Hospital, Siegen, Germany,

² Diakonie Jung-Stilling Hospital, Siegen, Germany,

³ Klinikum Chemnitz gGmbH, Chemnitz, Germany

Introduction: Spondylodiscitis and infective endocarditis (IE) rarely occur together, leading to complex clinical courses. This retrospective study investigates the relationship between the two conditions by analyzing data from a single-center patient cohort. The objective is to identify clinical patterns and propose diagnostic criteria for spinal infections associated with IE, improving diagnostic accuracy in cases of complicated bacteremia. Material and Methods: The study retrospectively analyzed electronic medical records from the Department of Neurosurgery at Klinikum Diakonie, Jung-Stilling, Siegen, Germany, over a ten-year period (2001–2020). A total of 97 patients diagnosed with spondylodiscitis were included, of whom 8 were also diagnosed with endocarditis. All data were anonymized and password-protected to ensure confidentiality. Results: The analysis showed that hematogenous spread was the most common route of infection in patients with both spondylodiscitis and IE. Endocarditis was more frequent in patients with multisegmental spinal involvement (10%) compared to those with single-segment spondylodiscitis (7.27%). Thoracic spondylodiscitis was present in 15% of patients without IE and 43% of those with IE. Patients with endocarditis more frequently underwent thoracic decompression and fusion surgery (43%) compared to those without IE (15%). Cervical spondylodiscitis was not associated with endocarditis. Leukocytosis was observed in 43% of patients with IE, compared to 24% of patients without heart valve involvement. C-reactive protein (CRP, normal value < 0.5 mg/dL) levels were significantly higher in patients with IE (median = 19.15 mg/dL) than in those with isolated spondylodiscitis (median = 8.7 mg/dL), with this difference becoming statistically significant after surgery (p = 0.018). Postoperatively, CRP levels normalized under antibiotic therapy in patients with isolated spondylodiscitis, while remaining elevated in the IE group. Preoperative creatinine levels were also higher in the IE group (p = 0.035), but decreased after surgery. Spondylodiscitis caused by contiguous spread was not associated with IE, even in multimorbid patients with a history of cardiac disease. Psoas abscesses were more frequently found in patients with contiguous spread of spondylodiscitis. Endocarditis occurred in 75% of patients with pre-existing heart disease, compared to 23.53% of those without (p = 0.00545). Epidural abscesses were more common in patients with both spondylodiscitis and IE. These patients also experienced more complicated hospital courses and frequent clinical deterioration. Proposed Diagnostic Criteria for Spinal Infections and IE: The following diagnostic criteria are proposed for identifying spinal infections in patients with IE, analogous to the modified Duke criteria for IE diagnosis (ESC Guidelines 2015):

Major Criteria:

1. Positive imaging (MRI or CT) showing spinal infection.

2. History of cardiac disease increasing the risk for IE.

3. Manifest renal insufficiency.

4. Persistent elevation of CRP despite antibiotic treatment.

Minor Criteria:

1. Positive blood cultures with pathogens commonly associated with IE or spinal infections.

2. Multisegmental spinal involvement.

3. Predominant thoracic involvement, possibly due to septic emboli. Conclusion: These criteria aim to aid in the systematic diagnosis of spinal infections associated with IE, particularly in cases of complicated bacteremia. A structured approach may help identify serious infections earlier and improve outcomes in high-risk patients.

Ethics committee approval 2021-702-f-S

ID: 2503

RF180: Debridement and fusion combined with short-segment screws and rod fixation through anterolateral mini-access for the treatment of thoracic or lumbar infection

YuTong Gu ¹

¹ Zhongshan Hospital Fudan University, Shanghai, China

Introduction: To evaluate the feasibility, efficacy and safety of debridement and fusion combined with short-segment screws and rod fixation through anterolateral mini-access for treatment of thoracic or lumbar infection. Material and Methods: 48 patients with single segment thoracic or lumbar infection from December 2019 to January 2022 were included. There were 42 cases of tuberculosis (TB), 2 cases of brucellosis, 4 cases of Escherichia coli. The abscess, infected and necrotic tissue were completely removed through anterolateral mini-access under direct vision. Through the same approach the fusion using only autologous rib bone, only autologous cortical iliac bone, titanium mesh, cage or artificial vertebra with autologous or allograft bone, was performed, and short-segment screws and rod fixation was undertaken with the pedicle screws inserted into involved vertebrae. The transthoracic approach was used for T8-11, transthoracic, transdiaphragmatic and retroperitoneal approach for T11-L1, retroperitoneal approach for L1-S1. Operative duration, blood loss, incision length and hospital stay were recorded. Pre- and postoperative visual analog scale (VAS) pain scores, Oswestry disability index (ODI), complications and images were also recorded. Results: There were operative duration of 173 (95-206) min, blood loss of 280 (35-450) ml, incision length of 52 ± 11 mm and hospital stay of 6 (4-8) days. VAS scores significantly dropped postoperatively (p < 0.001) and ODI significantly decreased 2 years after surgery (p < 0.001). Fusion has been achieved in 47 cases and there was 1 case of autologous cortical iliac bone broken. No internal fixation failure and other complication were found. Conclusion: Debridement and fusion combined with short-segment screws and rod fixation through anterolateral mini-access is a feasible, efficient and safe method in treating single segment thoracic or lumbar infection. It shows advantages of less surgical trauma and faster postoperative recovery. It is better for fusion to use titanium mesh, cage or artificial vertebra than only autologous bone.

ID: 710

RF181: Disparities in the clinical profile of spinal tuberculosis in Africa: a scoping review of management and outcome

Emmanuel Oladeji ^1,2 , Tochukwu Enemuo ² , Temitayo Anthony-Awi ² , Adedamola Olaniyi ² , Japheth Olaku ² , Peter Aransiola ² , Ridhwanullah Salawu ² , Gabriel Adedoyin ² , Olorunnisola Olatide ²

¹ St Richard's Hospital Chichester, Trauma and Orthopaedics, Chichester, United Kingdom,

² Surgery Interest Group of Africa, Trauma and Orthopaedics, Lagos, Nigeria

Introduction: Spinal tuberculosis (STB) is a significant contributor to non-traumatic myelopathy. There is a rising burden in Africa, in parallel with the high prevalence of human immunodeficiency virus. We conducted a scoping review to highlight the disparities in the management and outcomes of STB in Africa. Materials and Methods: This study used the preferred reporting systems for systematic review and meta-analysis extension for scoping review guidelines. AJOL, Embase, MEDLINE, Google Scholar, and Cochrane CENTRAL databases were searched to identify all relevant peer-reviewed articles published on the management of STB in African centres, excluding abstract-only articles, literature reviews, and meta-analyses. Results: 60 studies were eligible for inclusion, comprising data from 3416 patients aged eight months to 89 years (median, 32 years). Thoracic and lumbar segments were the most commonly affected vertebral regions (Thoracic = 42.7%; Lumbar = 35.9%). The most common clinical features were back pain and neurological deficits. Lack of essential laboratory and imaging diagnostic infrastructure was a common problem. Patients received antitubercular therapy (ATT) for varying durations and only 18.3% underwent surgery. A favourable outcome was achieved in 51.6% of patients, 20.3% developed a permanent disability, and the mortality rate was 2.1%. Treatment outcome was adversely affected by a high rate of late presentation and treatment default. Conclusions: ATT remains the mainstay of treatment, however, the duration of treatment varied widely among studies. Further research is required to explore the feasibility and efficacy of short-course ATT in treating STB in the African population.

ID: 2816

RF182: Evaluating the impact of the high-pressure irrigation and topical vancomycin on CRP levels in spine surgery: effective or not?

Betul Yaman ¹ , Samet Dinç ¹ , Hediye Erzurumlu ¹ , Inan Uzunoglu ¹

¹ Ministry of Health, Etlik City Hospital, Neurosurgery, Ankara, Türkyie

Introduction: Surgical site infections (SSIs) are a significant issue in spine surgery. The local use of antibiotics, especially vancomycin, has been explored as a preventive measure. However, the effectiveness of topical vancomycin in spinal surgery is debated. While some studies suggest it reduces SSIs, others report no clear benefit. Some meta-analyses of randomized trials have found no conclusive evidence that topical vancomycin reduces infections. Interestingly, some studies have also found that intrawound vancomycin powder is associated with an acute inflammatory response. The aim of our study is to investigate the effects of high-pressure saline irrigation with prophylactic topical application of vancomycin powder on CRP levels in initial spinal surgery. Material and Methods: Our study includes patients who developed discitis following spinal surgery within the last year in the Neurosurgery Clinic at Etlik City Hospital. Statistical analyses were performed using JASP Statistics version 0.18.3 (Apple Silicon) software (University of Amsterdam, Netherlands) and statistical significance was set at p < 0.05.We analyzed several parameters, including patient gender, age, CRP levels pre-operatively and at weeks 1, 2, 4, 6, 8,and 12 post-operatively, the level of surgical procedure performed(categorized vertebra levels into 1-2, 3-4, or 5 and more),positive surgical site cultures, post-operative antibiotic use, ODI (Oswestry Disability Index) scores, pre-operative neurological examination (MRC scale), post-operative neurological outcomes, complications (systemic, surgical site infections),and intraoperative irrigation techniques (topical vancomycin powder plus high pressured irrigation). Results: Among the 24 patients included in the study,13 were female, with a mean age of 55.8 years (SD = 12.1), and 11 were male, with a mean age of 61.2 years (SD = 14.3).There was a significant difference between pre-operative and post-operative CRP levels at week 1 (p = 0.005) and week 12 (p = 0.018),but no significant difference was found between pre-operative CRP and the surgical procedure performed (p = 0.838).A significant difference in pre-operative CRP levels was observed between male and female patients (p = 0.046), while no significant difference was found in CRP values between groups with positive and negative surgical site cultures. There was a significant difference between the levels of surgical procedure performed and the presence of positive surgical site cultures (p = 0.04). In patients who received post-operative antibiotics, CRP levels at week 6 were significantly different (p = 0.007), and post-operative week 1 CRP levels showed significant differences when compared to all other post-operative CRP values (p < 0.001). However, no significant difference was observed between intraoperative irrigation groups and groups with or without positive culture growth (p = 0.219), or between antibiotic use and culture results (p = 0.089). Additionally, there was a significant difference between post-operative complications and CRP levels at week 4 (p = 0.013), but no significant difference was found when comparing ODI score, MRC scale score, and post-operative neurological outcomes with all CRP levels. Lastly, no significant difference was observed between CRP levels in the group that received high-pressure irrigation plus topical vancomycin powder and the group that did not. Conclusion: Although the effects of prophylactic vancomycin and high-pressure irrigation on CRP levels could not be demonstrated, pre-operative and post-operative week 1 CRP levels are important for monitoring patients. The significance of post-operative week 12 CRP levels suggests that patients should be followed up for at least 3 months. Post-operative antibiotic use did not affect culture growth, but its effect on CRP levels at post-operative week 6 may be attributed to the continuation/discontinuation of antibiotic therapy and inflammatory processes related to healing. Also, there is a significant association between the level of surgery and positive surgical site cultures. Additionally, we can conclude that the patient's disability,as well as pre-operative and post-operative neurological examinations, did not influence CRP levels. Increasing the number of patients in the study would provide further insights.

Keywords: Spine surgery, infections, topical vancomycin, high pressured irrigation

ID: 2178

RF183: Profile of patients admitted with spondylolidiscitis in the neurosurgery service at a private institution

François Dantas ¹ , Fernando Luiz Dantas ² , Barbara De Campos Mattos Campos ³ , Victor Kelles Tupy Da Fonseca Fonseca ⁴

¹ Krembil Neuroscience/ Western Hospital, Neurosurgery, Toronto, Canada,

² Biocor/Rede D'or Hospital, Neurosurgery, Post-Graduation Faculdade de Ciências Médicas de Minas Gerais, Belo Horizonte,

³ Biocor/Rede D'Or Hospital, Neurosurgery, Belo Horizonte, Brazil,

⁴ Post-Graduation Faculdade de Ciências Médicas de Minas Gerais, Post-Graduation, Belo Horizonte, Brazil

Introduction: Spondylodiscitis is an infection of the intervertebral disc and adjacent vertebral bodies. It is a rare disease, with an insidious onset and a clinical picture composed of non-specific signs and symptoms and late appearance of radiological changes, which, in most cases, leads to a delay in diagnosis and consequent treatment of the condition. Objectives: To evaluate the profile of patients admitted with a diagnosis of Spondylodiscitis between 2002 and 2020 Material: Retrospective observational study by reviewing the medical records of patients admitted to a private institution between 2002 and 2020 with a diagnosis of spondylodiscitis. The epidemiological data of the patients were analyzed, such as gender, average age and clinical aspects such as pre-existing comorbidities and site of spinal involvement, the average time of treatment with intravenous antibiotics and the response to it based on the comparison between the values of inflammatory markers on admission and before hospital discharge. Patients underwent tomography, resonance and bone scintigraphy and, in some cases, biopsy for diagnostic confirmation. Results: 52 cases were observed, 31 male. The mean age of the patients was 61a (33-84y) years (S.D. = 12.68). Baseline PCR averaged 68.57 (4.9-208.9); The initial VHS averaged 66.37 (7-126). The average antibiotic time was 5.08 weeks (4-6). The high CRP was on average 15.22 (S.D. = 10.41), with the lowest CRP being 1.50 and the highest being 52.60; The high ESR was on average 38.81 (S.D. = 25.70), with the lowest ESR being 12 and the highest being 118. In 68.0% of cases there was a community infection and 32.00% had a hospital infection. In 35% of patients, a disc biopsy was performed. The majority of patients (73%) had negative disc/bone culture results. Among the positive results were Citrobacter sp, CoNS, E.coli, Enterobacter sp, Enteroccus sp, M.morganni, P. Aeruginosa, S aureus (which was the only culture present in more than one individual) and multidrug-resistant Serratia. In addition, two individuals presented more than one type of culture. Blood culture was performed in 81% of cases, that the majority (80.95%) tested negative. Furthermore, among the positive results were E. Faecalis, Enterobacter, S.aureus and Serratia. The lumbar spine was the most affected site with 60% of cases, 20% in the thoracic, 12% in the lumbosacral, 4% in the thoracolumbar and 4% in the cervical spine. Among the comorbidities present, 46% had arterial hypertension, 23% had diabetes mellitus, 8% had hypothyroidism, 4% had decompensated liver cirrhosis; 4 had hypercholesterolemia, 4% had bacterial endocarditis, 4% had rheumatoid arthritis Conclusions: Spondylodiscitis should be part of the differential diagnosis in patients between 50 and 70 years of age, with neoplasia or comorbidities such as Diabetes Mellitus, Liver Cirrhosis, Dialytic Renal Insufficiency or Valvular Diseases, who present with intense and disabling low back pain, associated with systemic signs and symptoms such as weight loss, hyporexia and fever. Observing neurological severity criteria, such as new or progressive appendicular motor deficit and segmental vertebral instability, is essential when deciding on surgical intervention.

ID: 1425

RF184: Lateral lumbar interbody fusion (LLIF) surgery, psoas muscle size changes, and clinical findings: do they correlate?

Luke Jouppi ^1,2 , Clifford Pierre ^1,2 , Neel Patel ^1,2 , Julius Gerstmeyer ^1,2,3 , Bryan Anderson ^1,2 , Donald Davis ^1,2 , Zeyad Daher ¹ , Tara Heffernan ¹ , Daniel Norvell ⁴ , Amir Abdul-Jabbar ^1,2 , Rod Oskouian ^1,2 , Jens Chapman ^1,2

¹ Seattle Science Foundation, Seattle, United States,

² Swedish Neuroscience Institute, Seattle, United States,

³ Ruhr University Bochum, BG University Hospital Bergmannsheil, Department of General and Trauma Surgery, Bochum, Germany,

⁴ Spectrum Research Consulting, Tacoma, United States

Introduction: Lateral Lumbar Interbody Fusion (LLIF) is a minimally invasive fusion technique seeking to reduce soft tissue damage as compared to similar alternatives. However, major concerns have been raised over nerve injury after LLIF, with reported postoperative concerns over sensory deficits and iliopsoas weakness. This study sought to determine if LLIF is associated with a change in psoas muscle size, postsurgical hip flexor (HF) weakness, or lower extremity numbness after surgical intervention. Methods: We conducted a retrospective review of LLIF-consecutive patients at our institution from 2016 to present. Cross-sectional area of the psoas was measured bilaterally at mid-body of L3. Change from preoperative to postoperative ipsilateral and contralateral measurements of psoas area, HF strength, and numbness were compared. Postoperative imaging was required to be at least one month after the surgery. Results: Ninety-three LLIF patients met our initial criteria, and 37 (40%) had imaging available for comparison. Ninety-three LLIF patients met our initial criteria, and we used a matched cohort of 27 patients with CT patients and 27 with MRI. On CT imaging, there was a significant decrease in ipsilateral psoas area (p = 0.05) after LLIF but no significant change in contralateral psoas area. Contralateral HF strength increased postoperatively at least one grade (p = 0.04), but no significant changes in ipsilateral HF strength, numbness, or contralateral numbness were found. Of the 32 patients with documented symptoms, 9.6% (n = 9) of patients reported preoperative numbness and a different 9.6% reported postoperative numbness (n = 9). Resolution of postoperative symptoms occurred between 1 to 7 months (2.47 ± 1.97), except for three patients who required further surgery. Conclusion: LLIF may be associated with decreases in ipsilateral psoas size. Our study showed no significant correlation in ipsilateral numbness or weakness after LLIF and change in psoas size, though future studies with greater sample size may be helpful to support these findings.

ID: 1500

RF185: Long term clinicoradiological outcome of cost-effective composite reconstruction in dorsal koch spine - an Indian perspective

Sudhir Srivastava ¹ , Saurabh Muni ²

¹ K.J.Somaiya Medical College & Research Centre, Department of Orthopedics, Mumbai, India,

² Zenon Multispeciality Hospital, Orthopedics, Mumbai, India

Introduction: In India tuberculosis is the commonest cause of chronic infection in dorsal spine leading to neurological deficit and deformity. Authors have devised a versatile approach to perform thorough neural decompression and reconstruction with use of cost effective implant and its hybrid innovation. Its long term functional and radiological outcome is being presented. Materials and Methods: In this retrospective study of surgically treated 153 patients of dorsal Koch spine, we analyzed the clinical and radiological outcome after a follow up of 10 years. Healed post- tubercular kyphotic deformity correction was excluded from the study. There were 88 males and 65 females. The age ranged from 5 years to 63 years. Out of 153 patients, 148 patients had varied grades of neurological deficit (Frankel’s grading) while 5 patients did not have any neurological deficit and were operated in view of significant column destruction and instability. 133 patients (Group A) were treated surgically by versatile approach where through a single curvilinear incision keeping the patient in lateral position, anterior decompression (through transthoracic) and posterior instrumentation on dorsal surface of column was done through same incision along with posterior decompression, in cases of circumferential compression. In this group, fixation was done by sublaminar wire and hartshill rectangle. In 20 patients (Group B) where the lesion was in lower dorsal region and required upper lumbar vertebrae fixation, pedicular screw fixation was done keeping the patient in prone position. In both the groups bony reconstruction was done using ribs and/or iliac crest graft. Adequate interbody (>2/3^rd of antero-posterior width) reconstruction, onlay anterior grafting and posterior interlaminar grafting was done in all the cases. The cost of implant in group A varied from Rs 2000 to 2500 per case while in group B it varied from Rs 8000 to 9000. These patients were followed at regular intervals, initially 3 monthly and later on yearly. At each follow up clinical and radiological assessment was done. Result: Out of 148 patients with neurodeficit, 142 recovered to grade 5 motor power and resumed their previous work. One patient remained paraplegic, one improved upto grade 2 but remained non-ambulatory. 4 patients had persistence of spasticity but could manage their job. Two patients of Group A had implant failure at distal end (one because of breakage of sublaminar wire and other because of buckling of strut graft) these were converted to hybrid fixation at lower end of hartshill. In two of the paediatric patient (proximal implant failure), implant was taken out at the end of 18 months & 2 years respectively. The loss of column correction varied from 4 to 12 degrees. Radiological outcome did not vary in Group A or Group B. Conclusion: Meticulous neural decompression, skillful preparation of osteogenic bed, autologous strut grafting and adequate stabilization of column gives excellent and long lasting clinico-radiological outcome even with cost effective implant in dorsal spine tuberculosis with its varied sequelae.

ID: 111

RF186: Odontogenic focus in pyogenic spondylodiscitis: a frequently overlooked entity

Ann Kathrin Joerger ¹ , Miriam Zahn ¹ , Carolin Albrecht ¹ , Markus Nieberler ¹ , Herbert Deppe ¹ , Maria Wostrack ¹ , Bernhard Meyer ¹

¹ Technical University Munich, Munich, Germany

Introduction: Primary spondylodiscitis occurs through the hematogenous spread of a pathogen entering the body via a point of entry. The infection's origin often remains unclear. During dental procedures or through minor traumas, oral bacteria can enter the bloodstream and disseminate throughout the body. An association with periodontal bacteria has been established for infective endocarditis. This study investigates spondylodiscitis patients, focusing on a potential odontogenic origin. Material and Methods: In a cohort of 340 consecutive patients with primary spondylodiscitis treated at our Level I Spine Center from 01/01/2018 to 12/31/2022, those with oral bacteria in blood cultures or disc tissue samples and available orthopantomograms (OPG) were retrospectively re-evaluated concerning an odontogenic focus. Radiological features indicating a dental focus included apical radiolucency, impacted teeth, residual roots, and vertical or cup-shaped bone loss. Patients with secondary spondylodiscitis from a previous operation (< 3 months) in the same segment were excluded. Results: We included 340 patients with a median age of 73 (31 - 94) years. A causative bacterium could be detected in 286 (84.1%) cases, either through blood cultures (18.2%), tissue samples from the disc space (42.7%), or both (38.1%). The most frequent infective focus was joint infection (14.1%), followed by ulcers of the extremities (10.3%) and urosepsis (10.0%). An odontogenic focus was initially identified in 8.9%. In 33.1% of cases, the source of infection was not found. Oral bacteria were found in 38 cases (13.3%). The most frequent oral bacterial species were Streptococcus dysgalactiae (15.4%), followed by Parvimonas micra (11.5%) and Streptococcus mitis (9.6%). Of the 38 cases with oral bacteria, six had an identified focus of the throat, and six had an initially clear dental focus. Of the remaining 26 cases, OPG was available for 14. Re-evaluation of OPG revealed an odontogenic focus in 9 out of 14 cases (64.3%). 2 of these cases had a concomitant infective focus (i.e., joint infection), while in 7 cases, initially, no infective focus was found. Conclusion: An odontogenic focus for spondylodiscitis is more prevalent than initially presumed, particularly in patients where no focus is identified at first sight. We therefore recommend a thorough diagnostic dental work-up as a standard procedure for patients with primary spondylodiscitis.

ID: 113

RF187: The 3D volumetric loss of bone mass within vertebral bodies is strongly correlated with the local mRNA RANKL/OPG ratio in vertebral osteomyelitis patients

Siegmund Lang ¹ , Hendrik Roetzheim ² , Sarah Peschke ² , Melanie Schindler ^1,3,4 , Jonas Krueckel ¹ , Josina Straub ¹ , Daniela Drenkard ² , Markus Rupp ¹ , Martijn Riool ² , Volker Alt ¹

¹ University Hospital Regensburg, Trauma Surgery, Regensburg, Germany,

² University Hospital Regensburg, Experimental Trauma Surgery, Regensburg, Germany,

³ Karl Landsteiner University of Health Sciences, Department for Orthopedics and Traumatology, Krems, Austria,

⁴ University Hospital Krems, Division of Orthopaedics and Traumatology, Krems, Austria

Introduction: The Receptor Activator of Nuclear Factor Kappa-B (RANK), its ligand (RANKL), and Osteoprotegerin (OPG) regulate bone resorption, with soluble RANKL (sRANKL) and soluble OPG (sOPG) proposed as biomarkers for bone diseases. Their role in vertebral bone loss during vertebral osteomyelitis (VO) remains unclear. This study aimed to examine the correlation between local mRNA RANKL/OPG ratios and vertebral bone loss in VO, and assess the sRANKL/sOPG ratio as a potential serum marker for bone loss. Material and Methods: Subsequent adult patients with VO were prospectively included and followed up for at least 12 weeks. Demographic information, treatment details, microbiological findings, and serum parameters (C-reactive protein (CRP) and white blood cell count (WBC)) were documented. Serum samples were taken at the time-point of initial diagnosis of VO (t0), one week after diagnosis (t1), and at the time point of surgery (if, applicable, ts). ELISA was used to determine serum levels of free sRANKL and sOPG. Bone samples from infected vertebral bodies were collected from surgically treated patients and the mRNA expression levels of RANKL and OPG were determined by RT-qPCR. The initial vertebral bone loss was quantified with 3D volumetric segmentation based on the initial CT scan (t0) using a previously established calculation method. Results: Included patients (n = 11; 68.1 ± 12.6 years; 63.6% male, 36.4% female) suffering from cervical (18.2%), thoracic (45.5%), and lumbar (36.4%) VO. In 45.5% of cases, a pathogen was identified. In 54.5% of cases, surgery was conducted, and bone samples were collected. The mean CRP concentration at t0 was 70.4 ± 48.5 mg/dL and decreased to 52.4 ± 40.9 mg/dL (t1) and the mean WBC decreased from 9.0 ± 2.0 cells/nL (t0) to 7.3 ± 2.9 cells/nL (t1). The mean free sRANKL concentration at t0 was 0.9 ± 0.5 pg/mL and decreased to 0.8 ± 0.4 pg/mL at t1 (p = 0.316). The mean free sOPG concentration at t0 was 707.7 ± 252.0 pg/mL and increased to 752.7 ± 354.4 at t1 (p = 0.389). This calculates to a mean free sRANKL/sOPG ratio at t0 of 1.54E-03±1.05E-03 which decreased until t1 to 1.48E-03 ± 1.10E-03 (p = 0.457). The mean calculated bone loss was 26.8 ± 13.1% (7.8 - 50.9%). We identified a strong and statistically significant correlation between the height of the local mRNA RANKL/OPG ratio (ts) and the amount of bone loss (r = 0.983, p < 0.001). There was a small and not significant correlation between the free sRANKL/sOPG ratio (t0) and the amount of bone loss (r = 0.133; p = 0.820). Lastly, there was a moderate correlation between the sRANKL/sOPG and local RANKL/OPG ratio without reaching statistical significance (r = 0.371; p = 0.526). Conclusion: VO was linked to significant 3D volumetric vertebral bone loss. The local mRNA RANKL/OPG ratio was strongly associated with bone loss, unlike the sRANKL/sOPG ratio. This study suggests the RANK/RANKL/OPG axis, as a potential therapeutic target to mitigate bone loss during VO. Further follow-up and a control group will enhance understanding of spinal infections' impact on bone metabolism in VO.

ID: 716

RF188: Comparison of vascular surgical outcomes between anterior lumbar interbody fusion and oblique lumbar interbody fusion

Hendrick Francois ¹ , Esteban Quiceno Restrepo ² , Benard Okai ¹ , Asham Khan ² , Mohamed Soliman ² , Shashwat Shah ¹ , Isabelle Stockman ¹ , Deanna Chan ¹ , Joseph St. Onge ¹ , Jeffrey Mullin ² , John Pollina ²

¹ Jacobs School of Medicine and Biomedical Sciences, Neurosurgery, Buffalo, United States, ² University at Buffalo Neurosurgery, Neurosurgery, Buffalo, United States

Introduction: Low back pain is a ubiquitous condition affecting more than 80% of Americans and surmounts up to $50 billion dollars annually within the US. Various etiologies of low back pain exist decreasing quality of life and encompasses spondylisthesis, lumbar spinal stenosis, and disc degeneration. Throughout the 21st century, advancements in surgical treatment for lumbar degenerative spine disease have steadily increased and advanced the field. The innovative work of physicians met with the complexity of degenerative pathology has created an arsenal of approaches today for the spine surgeon to use which include the ALIF, OLIF, DLIF, LLIF, and XLIF. Up until this point, there have been numerous comparative systematic reviews investigating postoperative complications between lumbar fusion approaches but none have primarily investigated vascular injury rates between the anterior lumbar interbody fusion and oblique lumbar interbody fusion. The aim of this study is to analyze and quantify injured blood vessels, estimated blood loss, and complications to mitigate complications when selecting an approach. Material and Methods: All full text English-language manuscripts studying the vascular complications between anterior lumbar interbody fusion and oblique lumbar interbody fusion approach were screened using Pubmed, and Embase. Results: A total of 112 articles were identified and 68 papers were selected. Two studies were prospective series and the remaining 110 were retrospective. All included studies totaled 13,517 patients with a total follow up of 30.23 months which ranged 8-209 months. In surgical treatment of lumbosacral disc pathology, vascular complications averaged 3.2% (95% 0.022-0.042) and 1.3% (95% 0.006-0.019) respectively in ALIF and OLIF approaches. Estimated blood loss per case averaged 109.04 ml (95% 83.09-134.98) vs 133.578 (95% 111.326-155.829) respectively in ALIF and OLIF approaches. ALIF studies had a total of 262 vascular injuries with the most common including the left common iliac vein 72% (190/262), left common iliac artery 9.9% (26/262), and the inferior vena cava 4.9% (12/262). OLIF studies had a total of 36 vascular injuries with the most common including the left segmental artery 36% (13/36), left common iliac vein 25% (9/36), and left iliolumbar vein 19% (7/36). Conclusion: Due to the wide range of surgical approaches and therapeutic overlap, comparison is crucial to mitigate complications. The ALIF approach compared to the OLIF demonstrated greater vascular injury and intraoperative blood loss. Although certain approaches are ideal for specific levels, spine surgeons must use the available data with discretion.

ID: 771

RF189: Underreporting of proximal junctional kyphosis and failure in adult spine deformity surgery: a multicenter radiological review using multiple diagnostic criteria

So Kato ^1,2 , Eric Klineberg ^2,3 , Caglar Yilgor ^2,4 , Michael Kelly ^2,5 , Lawrence Lenke ^2,6 , Christopher Shaffrey ^2,7 , Kenneth Cheung ^2,8 , Sigurd Berven ^2,9 , Yong Qiu ^2,10 , Yukihiro Matsuyama ^2,11 , Ferran Pellise ^2,12 , Jonathan N. Sembrano ^2,13 , Benny Dahl ^2,14 , Maarten Spruit ^2,15 , Ahmet Alanay ^2,16 , Stephen Lewis ^2,17

¹ The University of Tokyo, Tokyo, Japan,

² AO Spine Knowledge Forum Deformity, Davos, Switzerland,

³ UTHealth Houston, Houston, United States,

⁴ Acibadem Maslak Hospital, Istanbul, Türkyie,

⁵ Rady Children's Hospital, San Diego, United States,

⁶ The Spine Hospital, New York, United States,

⁷ Duke University, Durham, United States,

⁸ The University of Hong Kong, Hong Kong, Hong Kong,

⁹ University of California, San Francisco, San Francisco, United States,

¹⁰ Drum Tower Hospital of Nanjing University Medical School, Nanjing, China,

¹¹ Hamamatsu University School of Medicine, Hamamatsu, Japan,

¹² Hospital Universitari de la Vall d’Hebron, Barcelona, Spain,

¹³ University of Minnesota, Minneapolis, United States,

¹⁴ Rigshospitalet, Copenhagen, Denmark,

¹⁵ Sint Maartenskliniek Nijmegen, Ubbergen (near Nijmegen) Gelderland, Netherlands,

¹⁶ Acibadem Mehmet Ali Aydinlar University School of Medicine, Istanbul, Turkey,

¹⁷ University of Toronto, Toronto, Canada

Introduction: Proximal junctional kyphosis (PJK) and its severe form, proximal junctional failure (PJF), are common adverse events following adult spine deformity (ASD) surgery, which unfortunately are also frequently underreported due to its variable clinical significance and radiological subtlety. Several PJK criteria have been reported in the literature, affecting the reported PJK/PJF rates. Additionally, subjective clinician diagnoses are prone to bias, posing a challenge in data interpretation. The purpose of the present study was to review radiological data from an international multicenter study of ASD to determine PJK/PJF rates based on different diagnostic criteria and compare them with clinicians’ diagnostic reports. Material and Methods: A prospective, multicenter, multi-continental, observational longitudinal cohort study was conducted by AO Spine. The study enrolled patients aged ≥ 60 years undergoing primary spinal fusion surgery of ≥ 5 levels for coronal, sagittal or combined deformity (PEEDS). Patients with pre-, and 2-year post-operative standing whole spine X-rays were included in the analyses (n = 166). Proximal junctional angle (PJA) was defined as the sagittal Cobb angle between the upper instrumented vertebra (UIV) and UIV+2. PJK/PJF was diagnosed by the following criteria: (1) Glattes’ PJK: (a) ∂PJA (pre-operative vs. 2-year post-operative) > 10° and (b) PJA at 2-year post-operative > 10°, (2) ASLS-1 PJF: (a) ∂PJA > 20°, (b) UIV and/or UIV+1 fracture with >20% height loss, (c) screw dislodgement, and (d) spondylolisthesis at UIV+1/UIV > 3 mm, (3) Consensus-based PJF: review by four experts focusing on (a) bone failure: UIV/UIV+1 fracture, (b) construct failure: screw pull-out/cut-out, hook dislodgement, and (c) junctional failure: spondylolisthesis and posterior ligamentous complex damage. Lastly, adverse events were collected from the case report form (CRF), and PJK was defined when denominated as “junctional pathology” or “compression fracture” by 2 years post-operatively. Results: The detailed radiologic review identified Glattes’ PJK in 84/163 (51.5%) cases, whereas ASLS-1 PJF was diagnosed in 75/164 (45.7%) cases, with only 58 cases (35.6%) fulfilling both criteria. Consensus-based PJF was reported in 87/165 (52.7%) cases. The kappa values against ASLS-1 PJF were 0.47 (95% confidence interval [CI]: 0.34 - 0.61) for Glattes’ PJK, showing moderate agreement, and 0.81 (95%CI: 0.72 - 0.90) for consensus-based PJF, indicating almost perfect agreement. The most common criterion for the ASLS-1 PJF diagnosis was fracture at UIV or UIV+1 (81.3%), followed by ∂PJA > 20° (44.0%) and screw dislodgement (29.3%). On the other hand, PJK reported in CRF was found in only 15 cases, indicating significant underreporting with a kappa value of 0.19 (95%CI: 0.09 - 0.29). Conclusion: PJK/PJF rates varied based on different radiologic criteria. PJK was underreported in PEEDS study in CRF filled by clinicians, in contrast to the radiologic assessment of PJK/PJF based on geometric definitions.

ID: 1272

RF190: Preoperative risk factors are predictive of complications and cost in adult spinal deformity surgery

Brendan O'Reilly ¹ , Pratibha Nayak ² , Cole Payne ¹ , Richard Hostin ³ , Eric Klineberg ¹

¹ University of Texas Health Science Center at Houston McGovern Medical School, Department of Orthopaedic Surgery, Houston, United States, ² HCA Healthcare Research Institute, Dallas, United States, ³ Southwest Scoliosis and Spine Institute, Dallas, United States

Introduction: Patients with adult spinal deformity (ASD) suffer from multifactorial symptoms, including debilitating back pain, neurological deficits all of which lead to disability. Surgical treatment can greatly improve quality of life; however, it is associated with high complication rates, impacting the cost of care. The need for a classification system for patient risk stratification and cost prediction is crucial. The International Spine Study Group-AO (ISSG-AO) developed a classification system specifically for ASD based on intervention to allow for more precise complication grading. Classifying complications based on severity and invasiveness can help surgeons better understand and predict impact on cost and other outcome measures. This study aims to identify preoperative risk factors associated with greater ISSG-AO complication scores and the relationship between worse scores and costs. Material and Methods: Patients undergoing surgical repair of ASD at 19-US based sites were enrolled. Patients were assessed preoperatively for study inclusion, and postoperative complications were recorded. Complications were graded by level of invasiveness according to the ISSG-AO system: grade 0 (none); grade 1, mild (e.g., medication change); grade 2, moderate (e.g., ICU admission); grade 3, severe (e.g., reoperation related to surgery of interest). The cost of complications for each patient was collected to calculate the average total cost of care and categorized following the ISSG-AO system. Results: A total of 638 patients underwent surgery involving > 4 fusion levels (69% female, mean age 61.2 years) were enrolled. Sixty-five percent were classified as overweight or obese, and 46% had one or more comorbidities. Of the patients, 51.3% experienced no complications, 19.7% had mild complications, 8.8% encountered moderate complications, and 20.2% faced severe complications. Preoperative risk factors for ASD showed with each additional year of age, the risk of severe complications rises by 2.9%. Also, each additional unit increase in BMI raises the risk of severe complications by 6.9%. Patients with an additional medical condition have a 21.3% higher chance of facing moderate complications and a 17.3% greater risk of severe complications compared to those without the condition. In the adjusted model, each extra day of length of stay (LOS) increased the likelihood of experiencing mild complications by 9.8%, moderate complications by 11.8%, and severe complications by 12.25%. With worse grades associated with greater LOS, we found that the average direct cost for LOS was $18,926 (SE, $1,179). For patients without complications, the direct cost for LOS was estimated at $17,867 (SE, $1,702), while for those with severe complications, it was $20,428 (SE, $3,275). Conclusion: In this multi-institutional study, we identified risk factors, namely BMI, age, and comorbid status, that are associated with worse complications as measured by ISSG-AO scoring. Patients with higher ISSG-AO scores tend to have longer LOS and incur more costs. This study helps provide better risk stratification for patients, and leads to improved preoperative counseling, and postoperative complication surveillance. With the recent development/integration of the ISSG-AO complication classification system for ASD the data collected can be used to assess the impact of specific complication categories and intervention severity on costs and outcomes.

ID: 1092

RF191: “Turn and die” - cardiac arrest after decubitus prone-to-supine turnover in spine surgery. Systematic review and two case reports

João De Oliveira ¹ , Alex Michel Daoud ¹ , Gabriel José Dos Santos ¹ , Lucas Viana ¹ , Victor Maraboti ¹ , Vinicius Guirado ¹ , Flavio Miura ¹ , Jefferson Walter Daniel ¹ , Jean De Oliveira ¹ , Jose Carlos Veiga ¹

¹ Division of Neurosurgery, Department of Surgery, Santa Casa de Sao Paulo School of Medical Sciences, Sao Paulo, Brazil, São Paulo, Brazil

Introduction: Cardiac arrest (CA) is a rare but disastrous complication in spine surgery when performed in the prone position. Reasons for intraoperative prone position CA or following the prone-to-supine position change are usually unknown. Likewise, the incidence of CA after decubitus prone-to-supine turnover is unclear. Therefore, a systematic review was performed, along to two cases reports, for doctors to be aware of this usually fatal surgical complication. Material and Methods: The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) recommendations were followed. A search of the MEDLINE/PubMed, Embase, and Web of Science databases was conducted to identify English-language articles. The following descriptors were applied: (“Spine surgery” OR “Spinal surgery”) AND (“Cardiac arrest” OR “Cardiopulmonary arrest”). The risk of bias in the studies was evaluated using the Cochrane Risk of Bias Tool. The two cases were collected retrospectively and described. Results: Thirty-two papers were found, reporting 37 cases of CA. Scoliosis correction was the most common surgery. Tumor resection was performed in one case. The most common etiology was pulmonary air embolism. CA during surgery was more common during the surgical procedure than post operative decubitus prone-to-supine turnover (6 cases). Overall, 17 cases resulted in death. We present two cases of intraoperative cardiac arrest during spinal surgery in our neurosurgery division. The first case is a 25-year-old female with thoracic pain and paraparesis due to a T3 vertebral metastasis from Luminal B breast cancer. CA occurred upon transitioning to the supine position after spinal fusion, and resuscitation was unsuccessful. Intraoperative ultrasound indicated pulmonary embolism. The second case involves a 48-year-old male with cervical pain and quadriparesis from an intradural extramedullary tumor at C7. After tumor resection, CA occurred during repositioning. Resuscitation was successful, but the patient died 23 days later due to pulmonary embolism. Conclusion: Cardiac arrest is a life-threatening complication in spine surgery regarding all spinal segments. The etiology is diverse, therefore surgical and anesthesiology teams must remain aware to prevent the “turn and die” situation from occurring besides acting swiftly when necessary.

ID: 1554

RF192: Impact of surgical termination level on reoperation rates following long segment posterior cervical spine surgery: a systematic analysis

Rowen Lin ¹ , Evan Minami ¹ , Jahan Jazayeri ¹ , Matt Sung ¹ , Kevin Mo ² , William Fang ² , Haley Nadone ³ , Sohaib Hashmi ³ , Don Park ³ , Yu-po Lee ³ , Nitin Bhatia ³ , Daniel Lee ² , Hao-Hua Wu ³

¹ Touro University Nevada, Henderson, United States,

² Valley Hospital Medical Center, Las Vegas, United States,

³ University of California, Irvine, Department of Orthopaedic Surgery, Orange, United States

Introduction: Corrective long segment posterior cervical spine surgery is a complex procedure that may lead to post-operative complications necessitating further reoperation. One critical decision point in such surgeries is the selection of the surgical termination level, particularly in relation to crossing the cervicothoracic junction (CTJ). This study investigates the impact of different surgical termination levels - C7, T1, and T2 - on reoperation rates to understand how these decisions influence clinical outcomes and to guide surgical strategies for improved patient outcomes. Material and Methods: We conducted a systematic review of the literature to evaluate the efficacy of different surgical termination levels. A comprehensive search was performed across multiple databases, including PubMed, SCOPUS, Web of Sciences, Embase, and Cochrane, covering studies published from inception to January 2024. The inclusion criteria encompassed studies reporting on reoperation rates following long segment posterior cervical spine surgery with documented termination levels at C7, T1, or T2. A total of 15 articles, involving 5,368 patients, were selected for analysis. Data on reoperation rates, operative time, blood loss, infection rates, hospital stay duration, and pseudarthrosis rates were extracted and compared between patients whose fusion terminated before and after the cervicothoracic junction. Results: Our analysis revealed two distinct cohorts: those with fusion termination at or before C7 and those with fusion termination below the cervicothoracic junction (T1 or T2). Patients with termination at C7 had a reoperation rate of 21.65% (range: 5.3% - 66%), an operative duration of 208.9 minutes (range: 149 - 276.5 minutes), blood loss averaging 252.8 mL (range: 116 - 657.5 mL), an infection rate of 6.4% (range: 0 - 10.5%), a hospital stay of 8.03 days (range: 4 - 18 days), and a pseudarthrosis rate of 10.5% (range: 2.7 - 21.2%). In contrast, patients with fusion termination below the cervicothoracic junction exhibited a lower reoperation rate of 13.9% (range: 2.2% - 68.7%), a longer operative duration of 258.7 minutes (range: 196 - 330 minutes), greater blood loss of 409.5 mL (range: 200 - 610.9 mL), an infection rate of 7.97% (range: 0 - 22.2%), a shorter hospital stay of 6.77 days (range: 4.0 - 11.6 days), and a pseudarthrosis rate of 7.35% (range: 2.17 - 10.96%). Common causes for reoperation in both cohorts included adjacent segment disease and pseudarthrosis, with revision occurring between 1 month and 5 years postoperatively. Conclusion: The findings suggest that termination of fusion below the cervicothoracic junction is associated with a lower incidence of reoperation and pseudarthrosis compared to termination at C7. However, this approach is linked to increased operative time, blood loss, infection rates, and length of hospital stay due to the complexity of fusing additional spinal levels. Despite these challenges, extending the fusion beyond the cervicothoracic junction may offer superior long-term stability, thereby reducing the need for subsequent surgeries. Surgeons must weigh these factors to balance operative risks with potential benefits in patient outcomes.

ID: 269

RF193: X-ray based deep learning artificial intelligence models for predicting proximal junctional kyphosis following adult spinal deformity surgery

Ted Shi ¹ , Varun Arvind ¹ , Justin Reyes ¹ , Cole Morrissette ¹ , Yong Shen ¹ , Mark M. Herbert ¹ , Roy Miller ¹ , Gabriella Greisberg ¹ , Matan Malka ¹ , Fthimnir Hassan ¹ , Zeeshan Sardar ¹ , Ronald A. Lehman ¹ , Lawrence Lenke ¹ , Joseph Lombardi ¹

¹ Columbia University Medical Center, New York, United States

Introduction: Proximal junctional kyphosis (PJK) following spinal deformity surgery remains very difficult to predict. Multiple radiographic measurements have been proposed as risk factors, indicating that imaging may provide useful knowledge for predicting PJK. Artificial intelligence possesses the potential to extract complex, relevant features from imaging, but there is a paucity of literature exploring this topic. Materials and Methods: 498 patients who underwent adult spinal deformity (ASD) surgery with 5 or more fusion levels from a single institution between 2015 and 2022 were included. Preoperative and initial postop anteroposterior (AP) and lateral x-rays were collected for all patients. A deep learning approach using convolutional neural networks (CNNs), which are commonly used for classifications tasks, was used to train and test a model to predict PJK outcomes. A total of seven different models were trained and evaluated using different combinations of the four x-ray image types as data inputs for the model. The seven models were preop AP only, preop lateral only, postop AP only, postop lateral only, preoperative (preop AP and preop lateral together), initial postoperative (postop AP and postop lateral together), and combined preoperative and initial postoperative (all four image types together). The models with multiple image types featured a multi-channel architecture, where each image was processed individually first and then integrated and analyzed all together. Model performances were evaluated using predictive performance metrics such as accuracy, sensitivity, specificity, and area under the receiver operating curve (AUROC) score. Additionally, gradient class activation mapping, which highlights hotspots on each image that are important to model decision-making, was conducted to qualitatively determine which regions of each image was important for the prediction of PJK. Analysis was performed using scikit-learn (v.1.3.2) in Python (v.3.12.1). Results: 25 of the 498 (5.0%) patients were found to have developed PJK post-operatively. When evaluating on a test cohort, the model performances, measured by AUC, were 0.65 (preop AP), 0.54 (preop lateral), 0.71 (postop AP), 0.69 (postop lateral), 0.59 (preoperative), 0.63 (initial postoperative), and 0.82 (combined preoperative and initial postoperative). Furthermore, the combined model achieved an accuracy of 67.3%, sensitivity of 100%, and specificity of 66.0%. Gradient class activation mapping highlighted that in preoperative images, the model focused on the overall deformity, alignment, and balance of the patient, whereas in postoperative images, the model focused on regions where instrumentation was present, especially in the upper thoracic region. Models utilizing data from the initial postoperative period typically performed better. Ultimately, the model that incorporated all data together had the highest performance. Conclusions: This is the first study to demonstrate the successful application of deep learning for the prediction of PJK. The success of the combined model compared to other standalone models indicate that PJK may be partially explained by changes between the preoperative and postoperative period. Deformity, alignment, balance, and surgical decision-making may also play important roles, as indicated by the gradient class activation maps. The results of this study demonstrate that deep learning possesses the capability to conduct advanced computational analysis to detect and synthesize complex features from perioperative imaging to predict PJK.

ID: 2496

RF194: GLP-1 receptor agonist medications alter outcomes of spine surgery

Joshua Wiener ^1,2 , Parshva Sanghvi ^1,2 , Katelyn Vlastaris ¹ , Thomas Mroz ² , Jonathan Belding ³ , Thomas Olson ⁴ , Kevin Francis ⁴ , John Adams ⁴ , Nicholas Bernthal ⁴ , William Sheppard ⁴

¹ Case Western Reserve University, School of Medicine, Cleveland, United States,

² Cleveland Clinic, Center for Spine Health, Cleveland, United States,

³ MetroHealth Medical center, Orthopedics, Cleveland, United States,

⁴ University of California - Los Angeles, Department of Orthopedics, Los Angeles, United States

Introduction: Spinal fusion is a prevalent surgical procedure globally, with over 400,000 cases performed annually in the United States alone. Obesity and diabetes, increasingly common among fusion patients, are associated with higher rates of post-operative complications such as infections, venous thromboembolisms, and non-union. As the incidence of obesity and diabetes rises, so does the demand for spinal fusion procedures and the associated risk of complications. Glucagon-Like Peptide-1 Receptor Agonists (GLP-1 RAs), originally developed for Type II Diabetes Mellitus management and recently approved for weight loss, have shown potential in improving bone health in animal studies. However, there is a lack of clinical data on the impact of GLP-1 RAs on post-operative outcomes following spinal fusion. Material and Methods: This retrospective, multi-center study utilized the TriNetX Research Database to identify diabetic and non-diabetic patients who underwent spinal fusion between 2008 and 2018. Patients were stratified based on being overweight (BMI ≥ 30) and GLP-1 RA usage. Propensity score matching was employed to create balanced cohorts, and orthopedic outcomes were compared between GLP-1 RA users and non-users. The primary outcomes included post-operative infection, readmission, revision surgery, and quality of life outcomes. Results: After matching, the study cohort consisted of 5,518 patients, with 4,010 classifying as obese. GLP-1 RA use was associated with significantly reduced post-operative infection rates (HR = 0.473 for obese; HR = 0.394 for non-obese), fewer revisions (HR = 0.651, 95% CI = 0.509 - 0.832 for obese; HR = 0.569, 95% CI = 0.379 – 0.855 for non-obese), and decreased rates of muscle weakness and mobility abnormalities. No significant differences were observed in back pain or epidural injection rates between GLP-1 RA users and non-users. Conclusion: GLP-1 RA use in spinal fusion patients was associated with improved post-operative outcomes, including lower infection rates, fewer revisions, and better quality of life metrics. These findings suggest that GLP-1 RAs may be a valuable adjunctive therapy in managing surgical outcomes in diabetic and obese patients undergoing spinal fusion. Further prospective and animal-based studies are needed to confirm these findings and explore the underlying mechanisms.

ID: 262

RF195: Complications of cervical spine fusion in patients with postoperative COVID-19

Henry Avetisian ¹ , Nicole Hang ¹ , Andy Ton ² , William Karakash ¹ , Bahador Athari ¹ , Jeffrey C. Wang ¹ , Raymond Hah ¹ , Ram Alluri ¹

¹ Keck School of Medicine of USC, Department of Orthpaedic Surgery, Los Angeles, United States,

² University of California, Department of Orthpaedic Surgery, Irvine, United States

Introduction: COVID-19 is a respiratory virus associated with severe multisystemic complications including cardiopulmonary and coagulopathic events. Given that spine surgery similarly places patients at risk for venous thromboembolism, understanding the unique postoperative risks conferred by COVID-19 is important to understand, particularly given the seasonal occurrence of COVID-19 in tandem with the rising rates of cervical spine surgery. The objective of this study is to assess postoperative complications in patients undergoing cervical spine fusion subsequently diagnosed with COVID-19 within 30- and 90-days of their procedure. Methods: Using the Pearldiver Mariner Database, patients who underwent primary anterior cervical discectomy and fusion (ACDF) or posterior cervical spine fusion (PCF) for degenerative pathologies were queried from 2010 to Q3 of 2022 using Current Procedural Terminology (CPT) and ICD-9 and ICD-10 codes. Patients aged < 18 years, or with operative indications for trauma, malignancy, or infection were excluded. Patients were further stratified based on COVID-19 diagnosis within 30- and 90 days postoperative. Propensity matching based on age, sex, Elixhauser Comorbidity Index (ECI), and smoking was performed to create 1:1 cohorts of patients with postoperative COVID-19 diagnosis and those without. Complication rates were analyzed using conditional logistic regression analysis. Results: The PearlDiver database identified 484,289 patients who underwent cervical spine fusion during the study period, of which 8,800 were diagnosed with COVID-19 within 30 and 90 days postoperatively. The COVID-19 group was older and had a higher number of comorbidities (mean age = 59.67 + 11.53; ECI = 7.7 + 4.4) compared to the control group (mean age = 54.97 + 11.51; ECI = 4.7 + 3.7). On logistic regression analysis, those diagnosed with COVID-19 within 30 days showed higher risk for pneumonia (OR= 7.196, 95%-CI: 6.093-8.550, p < 0.001), deep vein thrombosis (DVT) (OR = 2.618, 95%- CI: 1.852-3.768, p < 0.001), acute COPD exacerbation (OR = 1.936, 95%-CI: 1.446-2.616, p < 0.001), and pleural effusion (OR = 1.495, 95%-CI: 1.134-1.980, p < 0.05). Those diagnosed with COVID-19 within 90 days revealed higher risk of pneumonia (OR = 6.021, 95%-CI: 5.192-7.011, p < 0.001), DVT (OR = 2.561, 95% CI: 1.876-3.547, p < 0.001), acute kidney injury (OR = 2.063, 95% CI: 1.750-2.439, p < 0.001), aspiration pneumonia (OR = 1.437, 95% CI: 1.041-1.994, p < 0.05), and acute COPD exacerbation (OR = 1.743, 95% CI: 1.359-2.246, p < 0.001). Discussion: Postoperative COVID-19 diagnosis significantly increases the risk of DVT, renal, and pulmonary complications following cervical spine fusion. Surgeons should emphasize the added benefit of preventative measures against COVID-19 in patients with multiple comorbidities undergoing spine surgery, particularly during seasons with peak COVID transmission.

Patients diagnosed with COVID-19 following cervical spine fusion are at greater risk for DVT, renal, and pulmonary complications.

ID: 442

RF196: The hidden risk: intracranial hemorrhage following durotomies in elective spine surgery

Julius Gerstmeyer ^1,2,3 , August Avantaggio ² , Clifford Pierre ^1,2 , Neel Patel ^1,2 , Donald Davis ^1,2 , Bryan Anderson ^1,2 , Periklis Godolias ⁴ , Thomas Schildhauer ³ , Amir Abdul-Jabbar ^1,2 , Rod Oskouian ^1,2 , Jens Chapman ^1,2

¹ Swedish Neuroscience Institute, Seattle, United States,

² Seattle Science Foundation, Seattle, United States,

³ BG University Hospital Bergmannsheil, Department of General and Trauma Surgery, Bochum, Germany,

⁴ St. Josef Hospital Essen-Werden, Department of Orthopedics and Trauma Surgery, Essen, Germany

Objective: Intracranial hemorrhage (ICH) after durotomy in elective spine surgery, though rare, can pose a significant risk to patient outcomes. Spine surgeries bear a risk of dural tears (DT) with potential of postoperative cerebrospinal fluid leakage (PCSFL). Excessive PCSFL can precipitate a decrease in intracranial pressure, potentially leading to ICH. Literature on ICH as a postoperative complication is scarce. The aim was to assess the incidence and risk factors of ICH in patients undergoing elective spine surgery. Methods: Utilizing the 2020 National Impatient Sample (NIS) adults (> 18 years) were selected by primary procedure category codes for spine fusion, discectomy, spinal cord decompression and cervicothoracic/lumbosacral nerve decompression. Exclusion criteria were trauma and malignancy. The primary outcome was occurrence of ICH. Comparative analysis and a multivariable logistic regression were used to identify independent risk. Results: In total, 40,990 patients met our criteria with an incidence of ICH at 0.08%. The ICH-group showed an increased length of stay and higher mortality compared to the control group. Spinal cord decompression, DT and PCSFL were significantly more frequent in patients with ICH. Alcohol, drug abuse and hypertension were significantly more prevalent in patients with ICH. DT, alcohol abuse and hypertension were independent risk factors for ICH. Conclusion: This study underscores the rarity and severity of ICHs following elective spine surgery, emphasizing awareness and looking for possible preventive measures. Our finding suggests that DT, as a complication of surgical techniques, as well as alcohol abuse and hypertension are significant predictors of ICH.

RF12: DEGENERATIVE LUMBAR SPINE SURGERY 2

ID: 2924

RF197: Influence of workers’ compensation on outcomes in spinal endoscopic surgery

Prashanth Rao ^1,2,3,4 , Andrew Berg ¹

¹ Brain and Spine Surgery, Bella Vista, Australia,

² Norwest Private Hospital, Department of Neurosurgery, Bella Vista, Australia,

³ University of New South Wales, Sydney, Australia,

⁴ Macquarie University Hospital, Department of Neurosurgery, Macquarie Park, Australia

Introduction: Workers’ compensation is associated with worse post-operative outcomes in spine surgery. However, there is not much data on endoscopic spine surgery. This retrospective study of prospectively collected data analyses the influence of Workers’ compensation (WC) on the outcomes of endoscopic spinal surgeries in an Australian single-centre Neurosurgical practice to explore this relationship. Material and Methods: This retrospective analysis included 270 patients with spinal conditions who had undergone endoscopic surgery between August 2021 to June 2024. Comprehensive patient data, such as demographic information, preoperative clinical status, intraoperative details, clinical complications, and postoperative outcomes, were collected from electronic medical records. Measurable surgical outcomes include Visual Analogue Scale (VAS) leg pain scores, VAS back pain scores, Oswestry Disability Index (ODI), Roland-Morris Disability Questionnaire (RMDQ) scores, and the Quality-of-life EuroQol-5 Dimensions Questionnaire (EQ5D) scores. These outcomes were assessed using Descriptive statistics, Estimation-Stats package, and Spearman’s rank correlations, considering a p-value < 0.05 as statistically significant. Results: The analysis revealed a significant negative correlation between WC status and 6.12 week postoperative improvements in ODI (r = -.25, p = .017), RMDQ (r = -.29, p=.002), VAS Back (r = -.21, p = .017) and VAS Leg pain scores (r = -.36, p < 0.001), indicating that WC status is associated with less postoperative improvement. These were not reflected in EQ5D scores, where WC had no effect (p = .27). At 6-9 months, these negative correlations remained for VAS Back (r = -.31, p = .01), VAS Leg (-.47, p = 0.001) but disappeared for ODI (p = .8), RMDQ (p = .18) and EQ5D (p = .069). Despite variations in disability improvement, the WC group experienced pain relief postoperatively. Conclusion: This is the first study looking at the effect of WC status on endoscopy surgical outcomes. WC has a significant inverse relationship with short-term improvements in pain and disability except EQ5D5L following endoscopic spinal surgery. But this inverse relationship disappeared at medium term in disability while persisting in back and leg pain. These indicate the WC patients, in comparison to non-WC patients, experienced less improvement in pain in the short term and medium term however disability improvement is similar in medium term. Further data is needed to establish improvements in the long term.

ID: 431

RF198: Evaluating recovery rates and outcomes following single-level vs. multi-level lumbar interbody fusion

Ara Khoylyan ¹ , Noah Coleman ¹ , Alex Tang ² , Matthew Parry ² , Tan Chen ³

¹ Geisinger Commonwealth School of Medicine, Wilkes-Barre, United States,

² Geisinger Health, Orthopaedic Surgery Northeast Residency, Wilkes-Barre, United States,

³ Geisinger Health, Department of Orthopaedic Surgery, Wilkes-Barre, United States

Introduction: Single-level lumbar interbody fusions have been associated with lower rates of post-operative complications and improved subjective outcomes in comparison to multi-level fusions. There is limited available data evaluating rate of recovery and clinical trajectory following single level and multiple level transforaminal lumbar interbody fusion (TLIF) and posterior lumbar interbody fusion (PLIF). This study aims to address this gap by characterizing the clinical trajectory, complication rates, and rates of improvement following these procedures. Material and Methods: A retrospective review was conducted of patients who underwent elective TLIF or PLIF for degenerative spinal pathology between 2019-2023. The patient population was separated into single-level and multi-level cohorts for comparative analysis. Patient demographics and longitudinal Oswestry Disability Index (ODI) and Patient-Recorded Outcomes Measurement Information System (PROMIS) scores were collected at baseline and at 6 weeks, 3 months, 6 months and 12 months post-operatively. Maximum medical improvement (MMI) was defined as the point where over 90% of the cohort achieved a minimal clinically important difference (MCID). MCID was defined as an ≥ 8-point improvement on PROMIS or ≥ 10-point improvement on ODI between the pre-operative and any post-operative timepoint. Descriptive and inferential statistics were performed. Results: 99 patients undergoing single-level and 29 patients undergoing multi-level lumbar interbody fusion were included with available patient reported outcomes measure scores (PROMs). No demographic differences were observed between cohorts for age (56.1 years vs. 55.3 years, p = 0.774), BMI (30.9 kg/m² vs. 31.5 kg/m², p = 0.688), pre-operative A1c (5.7% vs. 5.6%, p = 0.325), or gender (61% female vs. 48% female, p = 0.237). There were no observed differences in post-operative complication rate (7% vs. 7%, p = 0.974) or procedure type (25% TLIF vs. 32% TLIF, p = 0.467). Both cohorts achieved similar clinical improvement at one year for ∆ODI (Single: -21.2, Multi: -24.9, p = 0.184) and ∆PROMIS-Physical (Single: 7.5, Multi: 8.7, p = 0.223). The multi-level cohort had significantly improved ODI scores at 6 months (Single: 26.9, Multi: 18.2, p = 0.013), and reached MMI by 6 months based on ∆ODI, exhibiting a significantly quicker rate of achievement (Single: 70% achieved, Multi: 93% achieved, p = 0.014). By the end of the survey period, 97% of patients who underwent multi-level fusion had achieved MCID in comparison to 76% of the single-level cohort (p = 0.014) and had a significantly greater likelihood of achieving MCID with ∆ODI at 1 year (OR 6.884, p = .047). Subgroup analysis demonstrated that TLIF patients had significantly better outcomes compared to PLIF at 1 year based on both ODI (TLIF: 14.3, PLIF: 26.7, p = 0.007) and PROMIS-Physical (TLIF: 48.7, PLIF: 43.7, p = 0.030). Conclusion: Patients undergoing multi-level TLIF/PLIF reach maximum medical improvement at a quicker rate than those undergoing single-level fusion, without an increased incidence of post-operative complications. These results challenge previous literature and suggest that multi-level fusion procedures may offer a more favorable recovery trajectory by addressing the entirety of a patient’s degenerative picture instead of only the most symptomatic spinal level. This information can be valuable for optimizing pre-surgical planning, patient counseling, and managing post-operative expectations.

ID: 2431

RF199: Effectiveness and safety of the TOPS system for lumbar degenerative spondylolisthesis: a systematic review

Joao Victor Pereira Gonzalez ¹ , Rafael Silva ¹ , Gabriela Nunes e Brito ¹ , Luciano Carneiro Filho ¹ , Pedro Henrique Matos Oliveira ¹ , Antonio C. Marttos Jr ²

¹ Escola Bahiana de Medicina e Saude Publica, Salvador, Brazil,

² University of Miami Miller School of Medicine, Dewitt Daughtry Family Department of Surgery, Miami, United States

Introduction: Lumbar degenerative spondylolisthesis (LDS) is a prevalent spinal condition, particularly in elderly populations, causing significant disability. The Total Posterior Spine (TOPS) system provides a motion-preserving alternative, offering stabilization without the drawbacks of spinal fusion. This systematic review aims to evaluate the long-term effectiveness and safety of the TOPS system in the treatment of LDS. Material and Methods: A systematic review was conducted following PRISMA 2020 guidelines. EMBASE, PubMed/MEDLINE, Web of Science, and Cochrane databases were searched from its inception until September 19th, 2024. Inclusion criteria were full-text cohort and randomized controlled trials published in English, Portuguese or Spanish involving LDS patients treated with the TOPS system, with at least two years of follow-up. Results: Five prospective studies with 249 patients were included, with follow-ups ranging from 2 to 11 years and a mean participant age of 63. Across all studies, patients experienced significant reductions in both back and leg pain. Preoperative VAS scores for back pain ranged from 56.2 to 71, decreasing to a mean of 7 at 2 years and 16 at 5 years postoperatively. Leg pain VAS scores dropped from a preoperative range of 47 to 83.5 to 3 for left leg pain and 11 for right leg pain at long-term follow-up. Compared to traditional fusion, where VAS scores decreased to a mean of 30.9 for back pain and 21.1 for leg pain, the TOPS system demonstrated superior pain relief. Functional improvements were significant. Preoperative Oswestry Disability Index (ODI) scores ranged from 49.1 to 51.6, dropping to an average of 8.4 at 5 years, compared to a reduction to 21.1 for fusion patients. SF-36 physical component scores increased from 27.9 preoperatively to 79.8 at 5 years, while the mental component improved from 48.7 to 85.3, indicating substantial improvements in quality of life. Fusion patients showed a comparatively smaller increase in physical and mental component scores, with physical scores reaching 64% of the improvement seen in the TOPS group. Radiographic analysis confirmed preserved spinal mobility, with flexion-extension ROM maintained between 4.5° and 9° over the follow-up period. No significant progression of spondylolisthesis or spontaneous fusion was observed, demonstrating that the TOPS system effectively stabilizes the spine while preserving segmental motion. The safety profile of the TOPS system was favorable, with a low reoperation rate of 5.8%, compared to 8.8% for fusion procedures. Only one device failure was reported, requiring revision surgery. Adjacent segment degeneration was significantly lower in the TOPS group (0%) compared to the fusion group (54%), suggesting the TOPS system's ability to mitigate long-term complications. Conclusion: This systematic review demonstrates that the TOPS system significantly reduces pain, enhances function, and preserves spinal mobility in patients with lumbar degenerative spondylolisthesis, while also minimizing complications. These findings support the TOPS system as a strong alternative to spinal fusion. However, larger-scale studies are necessary to validate these outcomes and further assess long-term benefits.

ID: 228

RF200: Elevated alkaline phosphatase is associated with increased rates of pseudoarthrosis, readmission, and return to operating room in open but not minimally invasive lumbar arthrodesis surgery

Abhinav Sharma ¹ , Manaav Mehta ² , Frederik Heath ¹ , Nicole Goldenhersh ¹ , Jason Liang ¹ , Maziar Moslehyazdi ¹ , Nischal Acharya ³ , George Rublev ⁴ , Michael Steinhaus ⁵ , Hao-Hua Wu ¹ , Sohaib Hashmi ¹ , Don Park ¹ , Yu-po Lee ¹ , Zorica Buser ⁶ , Nitin Bhatia ¹

¹ University of California, Irvine, Department of Orthopaedic Surgery, Orange, United States,

² University of Massachusetts Chan Medical School, Worcester, United States,

³ University of California, Irvine, Department of Neurological Surgery, Orange, United States,

⁴ David Tvildiani Medical University, Tbilisi, Georgia,

⁵ The Spine Institute, Salt Lake City, United States,

⁶ NYU Grossman School of Medicine, Department of Orthopedic Surgery, New York, United States

Introduction: With the recent advances in surgical technology, minimally invasive surgery (MIS) for lumbar arthrodesis procedures have dramatically risen. MIS facilitates safer surgeries with similar results to open procedures. Postoperative pseudoarthrosis — malunion resulting in pain and instability — is an increasingly occurring complication due to overall larger procedure volumes. Alkaline Phosphatase (ALP), a biomarker of bone metabolism and inflammation, has been used to monitor bone and liver health. Herein, we examine the association between serum ALP and the incidence of pseudoarthrosis, readmission, and return to OR (ROR) in patients undergoing open versus MIS lumbar arthrodesis surgery. Material and Methods: Patients undergoing open (CPT 22633, 22558, 22533, 22630, 22612) and MIS (CPT 22586) lumbar arthrodesis surgery and who had documented serum ALP in the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database from 2015-2021 were included. Analysis included univariable and multivariable logistic regression that accounted for sex, smoking, diabetes, BMI, and uremia; further analysis stratified by American Society of Anesthesiologist (ASA) physical status classification. Results: In the open procedures (n = 39,524), elevated ALP was significantly associated with pseudoarthrosis (odds ratio [OR] 1.62, 95% confidence interval [CI] 1.03-2.55; OR 1.63, CI 1.03-2.56), hospital readmission (OR 1.78, CI 1.29-2.45; OR 1.65, 1.19-2.27), and ROR (OR 2.00, CI 1.37-2.93; OR 1.89, 1.27-2.72) in univariable and multivariable models, respectively. Patients with pseudoarthrosis were more likely to be male, diabetic, and obese; readmitted and reoperated patients were smokers, diabetic, obese, and uremic. Classifying by ASA, high ALP was associated with pseudoarthrosis (OR 2.60, CI 1.26-5.36) in ASA 2 models and ROR (OR 1.78, CI 1.12- 2.83) in ASA 3 models. In the MIS procedures (n = 207), elevated ALP was associated with pseudoarthrosis (OR 11.24, CI 1.25-101.01; OR 12.35, CI 1.11-137.75), but not readmission nor ROR. Smoking was associated with ROR. No other association was significant, including confounders and when stratifying by ASA. Conclusion: Elevated ALP is strongly associated with increased odds of pseudoarthrosis, readmission, and ROR in open lumbar arthrodesis surgeries, including when stratifying by ASA status. Variables that portend worse overall health—smoking, diabetes, obesity, uremia—were also associated with the outcomes of interest. Although elevated ALP is associated with pseudoarthrosis for MIS lumbar arthrodesis surgery, there were overall lower rates of readmission and ROR even when accounting for confounding factors and ASA status. These results may inform the surgeon’s decision to pursue open versus MIS lumbar arthrodesis surgery in patients with high ALP.

ID: 1928

RF201: Risk factor of cage subsidence following UBE-TLIF

Songwut Sirivitmaitree ¹

¹ Bandung Crown Prince Hospital, Udon, Thailand

Background: Lumbar interbody fusion has become a commonly performed procedure for the treatment of degenerative lumbar disorders. Biportal endocopic Tranforaminal lumbar interbody fusion (BE-TLIF) become popular after developed endoscopic system. However, BE-TILF can result in several complications such as subsidence of the polyetheretherketone (PEEK) cage is the most common perioperative complication. However, the literature about potential risk factors for cage subsidence has been lack. Therefore, this study aimed to report the incidence, and potential risk factors of PEEK cage subsidence following BE-TLIF. Study Design: Retrospective cohort study. Objective: This study aimed to report the incidence and potential risk factors of polyetheretherketone (PEEK) cage subsidence following BE-TLIF. Methods: The study included a retrospective cohort of 72 consecutive patients (30 men and 42 women; mean age, 55.4 years) who had underwent BE-TLIF between January 2020 to March 2022. Patients were classified into subsidence and non-subsidence groups. Cage subsidence and bony fusion were evaluated using computed tomography (CT) images with coronal, and sagittal plan obtained 6, 12 months after surgery. PEEK cage subsidence was defined cage sunk into an adjacent vertebral body by > 2 mm. Preoperative variables such as age, sex, body mass index, smoking status, corticosteroid use, operative level and multifidus muscle fatty degeneration were collected. Univariate and multivariate logistic regression analyses were used to analyze the risk factors of subsidence. Results: Total of the 72 patients and 82 levels were included in this study, 46 level (56.1%) met the subsidence criteria and 36levels (43.9%) without cage subsidence. The factors significantly associated with cage subsidence were (BMI) > 25.0 kg/m² (OR = 3.7, p < .001)), Higher PEEK cage height (OR = 4.2, p < .001), different anterior disc height between pre and post-operative (OR = 6.3; p < .001) Conclusions: Risk factors for subsidence in BE-TLIF were higher BMI, higher PEEK cage height, and Different anterior disc height between pre and post-operative.

ID: 954

RF202: Results of instrumented fusion surgeries with reduction of spondylolisthesis - Comparison of posterior, anterior and combined approaches

Martin Cmorej ¹ , Peter Durný ¹ , Vladimir Katuch ² , Branislav Kolarovszki ¹

¹ UNM Martin, Neurosurgery, Martin, Slovakia,

² UNLP Kosice, Neurosurgery, Kosice, Slovakia

Introduction: Spondylolisthesis is one of the most common spinal disorders. While the diagnosis of spondylolisthesis has changed little in recent years, there has been significant progress in its treatment. The management of begins with non-surgical methods, but after the failure of conservative therapy, surgical intervention is indicated. The optimal surgical approach remains a subject of controversy. Scientific studies do not provide a clear consensus on the type of surgical approach, nor on whether the reduction of spondylolisthesis is a better method compared to in situ fusion in terms of clinical outcomes, spinopelvic parameters, and the risk of complications Material and Methods: Our retrospective study examines and compares radiological and clinical parameters before surgery and 24 months postoperatively, focusing on the surgical approach and the extent of spondylolisthesis reduction in patients who underwent lumbar interbody fusion surgery between 2017 and 2022 at the Neurosurgery Clinic of University Hospital Martin and the Neurosurgery Clinic of University Hospital Košice. The total sample size is 204 patients, divided into three main groups: patients who underwent single-segment surgery via the transforaminal approach with spondylolisthesis reduction; the second group consisted of patients who underwent single-segment surgery via the transforaminal approach with in situ fusion (without spondylolisthesis reduction); and the third group comprised patients who underwent ALIF or LLIF surgery with spondylolisthesis reduction. We compared the impact of reduction and surgical approach on the resulting changes in sagittal balance, particularly focusing on lumbar lordosis and the difference in PI-LL values. We also closely examined preoperative and postoperative ODI score values. Results: The results of our study show that when comparing patients who underwent surgery using the TLIF approach, the average improvement in lumbar lordosis in the group with spondylolisthesis reduction was 2.2°. Conversely, the average deterioration in lumbar lordosis was -3.3° in the group of patients who underwent TLIF with in situ fusion. When comparing ODI scores preoperatively and postoperatively, we observed an average reduction of 38% in patients without spondylolisthesis reduction and 47% in patients with spondylolisthesis reduction. In the next part of the study, we compared spondylolisthesis reduction based on the surgical approach in two groups: patients who underwent surgery via the ALIF or LLIF approach and those who underwent TLIF surgery. In terms of lumbar lordosis, we achieved positive correction in both groups, with a more significant improvement in the ALIF/LLIF group (4°) compared to the TLIF group (2.2°). Postoperative reduction in ODI scores was comparable between the two groups, with a 47% reduction in the TLIF group and 45% in the ALIF/LLIF group. Statistical significance was achieved in all these measurements. Conclusion: The results of the retrospective study show that patients who underwent spondylolisthesis reduction experienced a more significant improvement in both lumbar lordosis and ODI scores compared to those who had in situ fusion. Among patients with spondylolisthesis reduction, a greater correction of lumbar lordosis was achieved using the ALIF or LLIF techniques compared to the TLIF approach. Postoperative changes in ODI scores between these two groups, however, showed no significant differences.

ID: 1010

RF203: Influence of pars defects and spinopelvic parameters on stand alone ALIF clinical outcomes - a long term review

Maxime Saad ¹ , Mitchell Hansen ²

¹ John Hunter Hospital, Neurosurgery, Orthopaedic Surgery, New Lambton Heights, Australia,

² John Hunter Hospital, Neurosurgery, New Lambton Heights, Australia

Introduction: Anterior Lumbar Interbody Fusion (ALIF) is a well known technique used to address low back pain and radicular pain with good results. However, the need to use additional posterior fixation is still a matter of debate, especially in the presence of unfavorable anatomical situations such as the presence of lytic spondylolisthesis or high sacral slopes. The aim of this study is to evaluate the consequences of high pelvic incidences and pars defects on the long term outcomes of stand-alone ALIFs. Material and Methods: All patients operated for an L5-S1 ALIF by two senior surgeons between January 2013 and September 2023 were included in this retrospective study. Active spinal infection, history of past L5-S1 fusion attempt and multiple level fusions were exclusion criteria for this study. The primary outcome was the rate of reoperations for additional posterior L5-S1 fixation. Secondary outcomes were Oswestry Disability Index (ODI) and visual analogue scale (VAS) scores for back and leg pain. Radiological data included pre-operative and post-operative disc height and lordosis as well as a measurement of pelvic parameters. Patients were separated in two groups: « low pelvic incidence (PI)» when PI was < 55° and « high pelvic incidence » when PI was > 55°. The relationships between the different study variables on the outcomes were evaluated by either Fischer's exact test, Chi square test, or Student's t test depending on the case, with a p-value threshold of 0,05 for statistical significance. Results: 94 patients aged 21 to 83 years old (mean 50) were included in the study. Mean follow up duration was 49 ± 29 months (20-101). Mean ODI went from 43,7 pre-operatively to 31,5 at last follow up. Back and leg pain mean VAS respectively went from 6.0 and 4.1 pre-operatively to 4.0 and 2.8 at last follow-up. 7 Patients had to undergo an additional posterior L5-S1 fixation (8.5%) at a mean 11.9 months delay (0-36.5). All these patients had a lytic spondylolisthesis (p < 0.05). No statistically significant association between high pelvic incidence and additional posterior fixation was found. No association was found between the presence of a lytic spondylolisthesis or a high pelvic incidence and ODI, back or leg VAS scores (p > 0.05). Conclusion: Stand-alone ALIF allows for good results in regards to ODI, back and leg pain VAS. It is however associated with a higher rate of reoperations in the presence of a lytic spondylolisthesis.

ID: 217

RF204: A proposal and preliminary testing of a novel MRI-based criterion for co-occurring degenerative features prior to lumbar discectomy

Tero Korhonen ¹ , Jyri Järvinen ¹ , Juha Pesälä ² , Marianne Haapea ³ , Pietari Kinnunen ² , Jaakko Niinimäki ¹

¹ Oulu University Hospital, Department of Diagnostic Radiology, Oulu, Finland,

² Oulu University Hospital, Department of Orthopedics and Traumatology, Oulu, Finland,

³ Oulu University Hospital, Research Service Unit, Oulu, Finland

Introduction: Preoperative degenerative features in the operated segment may increase the risk of low back pain (LBP) and leg pain following lumbar discectomy. Although prior research has demonstrated increased clinical value for co-occurring magnetic resonance imaging (MRI)-observed lumbar degenerative features over individual features in the context of LBP severity, the impact of preoperative co-occurring degenerative features on lumbar discectomy outcomes has not been previously evaluated. Material and Methods: To assess the co-occurrence of intervertebral disc (IVD)-related degenerative features prior to lumbar discectomy, the authors collaboratively developed a novel, literature-based criterion termed “Advanced Preoperative Degeneration” (APD). To fulfill the APD criterion, the operated segment was required to preoperatively exhibit at least two advanced-level phenotypes from the three included MRI-observed degenerative features of endplate damage (EPD), Modic changes (MC) and IVD degeneration. Based on previous studies on lumbar spine degeneration, the thresholds for advanced-level phenotypes were defined as follows: an area of damage covering ≥ 25% of the affected endplate for EPD, pure or predominant Modic changes type I (MC1) for MC, and a Pfirrmann grade ≥ 4 for IVD degeneration. The predictive value of the APD criterion for one-year lumbar discectomy outcomes was subsequently tested on a retrospective cohort of patients who underwent single-level lumbar micro- or endoscopic discectomy at a tertiary-level hospital. Patients were categorized into APD-positive, APD1/3, and APD0 groups based on the presence of two or more, one, or none of the required phenotypes, respectively. Controlling for demographic and clinical covariates, a mixed-effects model was employed to evaluate differences between these groups in improvement rates of one-year postoperative patient-reported outcome measures (PROMs), consisting of LBP and leg pain on a 0-100 Visual Analogue Scale (VAS), disability on the Oswestry Disability Index (ODI, 0-100), and quality of life measured by the EQ-5D-3L scale. Results: The study cohort included 140 patients (mean age 45.3 years, 81 [57.9%] male). Overall, significant improvements were observed in all PROMs following discectomy. However, at the one-year follow-up, the APD-positive group exhibited significantly higher leg pain and disability levels compared to the APD0 group, with estimated means of 33.8 versus 19.8 for leg pain (regression coefficient [B] = +26.5, p = 0.001) and 20.4 versus 13.6 for ODI (B = +10.7, p = 0.016), respectively. Conclusion: This study presents a novel approach by integrating preoperative co-occurring IVD-related degenerative features into a composite APD criterion that is both clinically and academically practical. The APD criterion demonstrated clinical significance, as its fulfillment was associated with significantly poorer short-term outcomes for leg pain and disability following lumbar discectomy.

ID: 1406

RF205: A prospective cohort study of outcome in lumbar spine pain intervention in kuching, sarawak

Thurgai Tharshainy ¹ , Bik Liang Lau ¹ , Eu Gene Teo ¹ , Sii Hieng Wong, Albert ¹

¹ Sarawak General Hospital, Kuching, Malaysia

Introduction: Low back pain (LBP) is the leading cause of disability globally. The prevalence of LBP is projected to surge to an estimated 843 million people by 2050, marking a 36.4% increase from 2020.The goal of this study is to prospectively evaluate the outcome of pain intervention in improving low back pain as an effective short-term pain reliever. Material and Methods: Patients of various age groups presenting with low back pain for more than 3 months, with a pain score greater than 5 and not resolving with analgesia and physiotherapy, were offered spinal injection intervention. These patients were seen in our clinic from September 2022 until February 2024. We performed 37 facet joint injections, 14 epidural injections, 22 transforaminal injections, and 8 radiofrequency ablations (RFA) under image intensifier guidance. Cooled radiofrequency ablation was conducted for 2 ½ minutes at 60°C, and transdiscal for 15 minutes at 50°C.The outcome was assessed based on complete relief or at least a 50% reduction from the initial pain score via the Visual Analog Scale (VAS) at immediate post-injection, 1 month, and 3 months post-injection. Patients with similar or greater pain scores than the initial presentation at the 3-month assessment were offered a second pain intervention. Results: RFA showed the greatest reduction in pain score, with 84% reduction immediately post-intervention, improving to 96% and 97% at the 1st and 3rd-month assessments, respectively. This was followed by epidural and facet injection techniques, which consistently showed greater than 50% pain reduction over the 3 months of follow-up. Transforaminal injection resulted in less than 50% pain reduction. Pearson Chi-square tests showed no significant relationship between the initial pain score and the reduction in pain score at the immediate, 1 month, and 3 months post-injection time points. Conclusion: RFA significantly reduces pain in short-term follow-up. Epidural and facet injections are crucial options for excellent short-term pain relief, especially for patients who have failed conservative management. A larger sample size with continuous follow-up is needed to assess the long-term efficacy of RFA, epidural, and facet injections.

ID: 1407

A018: Anterior cervical discectomy and fusion and carpal tunnel release surgery: a retrospective analysis

Ignacio Garcia Fleury ¹ , Catherine Olinger ¹ , Reagan Grieser-Yoder ¹

¹ University of Iowa, Orthopedics and Rehabilotation, Iowa City, United States

Introduction: Anterior Cervical Discectomy and Fusion (ACDF) and Carpal Tunnel Release (CTR) surgeries address different but related conditions—cervical radiculopathy and carpal tunnel syndrome (CTS), respectively. Both conditions involve the compression of nerves, which can lead to pain, sensory deficits, and loss of function. Cervical radiculopathy affects the cervical spine, while carpal tunnel syndrome involves the median nerve at the wrist. Given the overlap in symptoms and the proximity of the anatomical structures involved, there has been interest in exploring a potential relationship between these conditions. The double crush syndrome hypothesis suggests that a proximal nerve compression, such as that occurring in cervical radiculopathy, can increase the vulnerability of the distal nerve (in this case, the median nerve in the carpal tunnel) to additional compression. This theory has led to speculation that patients undergoing ACDF for cervical spine issues may have a higher propensity to develop CTS, thus requiring CTR surgery. The present study investigates this relationship to identify patterns and potential prognostic factors that might link the two surgeries. Previous studies have shown varying levels of association between cervical radiculopathy and median nerve compression. Some studies suggest that a more proximal nerve lesion makes the distal nerve more susceptible to entrapment, while others argue that additional factors, such as systemic conditions (e.g., diabetes) or biomechanical stress, may play a role in this co-occurrence. This study builds on existing knowledge by retrospectively analyzing a cohort of patients who underwent ACDF, assessing the incidence of CTS and the subsequent need for CTR surgery. Material and Methods: A retrospective analysis used data from 504 patients who underwent ACDF surgery at a single institution between 2010 and 2020. Demographic variables included age, gender, occupation, and relevant medical comorbidities such as diabetes and smoking history. Surgical data collected included the specific levels of cervical fusion, duration of surgery, and any recorded intraoperative complications. Patients were grouped based on whether they had undergone CTR surgery or had been diagnosed with CTS. The main outcomes measured were the incidence of CTR surgery following ACDF and the time between the two surgeries. Results: Of the 504 patients who underwent ACDF, 51 patients (10%) had either undergone CTR surgery or had CTS documented in their medical records. Among these, 16 patients (31%) had both a diagnosis of CTS and underwent CTR surgery. Thirteen patients had CTR surgery without a previous diagnosis of CTS, while 22 had CTS documented without undergoing surgery. Conclusion: This study demonstrates a notable association between ACDF and the subsequent development of CTS, leading to CTR surgery in a subset of patients. While the exact mechanisms remain to be fully elucidated, the results suggest that patients undergoing ACDF should be closely monitored for signs of carpal tunnel syndrome. Further research is needed to understand the relationship between cervical and median nerve compression fully and to identify preventative strategies that could reduce the likelihood of CTR surgery in ACDF patients. These findings contribute to the growing body of evidence supporting the double crush syndrome hypothesis.

ID: 934

RF206: The importance of preoperative analysis of lumbo-pelvic parameters in the prevention of L5-S1 adjacent segment disease after lumbar fusion

Meddeb Mehdi ¹ , Hachicha Hassan ¹ , Safouen Ben Brahim ¹ , Amine Chabchoub ¹ , Khalil Habboubi ¹ , Mondher Mestiri ¹

¹ Kassab Institute, Adults, Manouba, Tunisia

Introduction: Posterior lumbar fusion is a common surgical procedure performed in many clinical situations, especially in degenerative conditions. Arthrodesis ensure stability and good functional results, but also lead to mechanical overloading of the underlying and especially the overlying discs, resulting in disc changes and thus adjacent segment disease. Proximal adjacent syndrome has been well studied in the literature, but few studies have investigated the development of adjacent syndrome in the distal segment, particularly at the L5-S1 level. The aim of our work was to study the value of preoperative analysis of lumbopelvic parameters in preventing L5-S1 adjacent segment disease after floating lumbar fusion (arthrodesis sparing the L5-S1 disc). Material and Methods: We analyzed the results of 53 patients who underwent surgery in our department for degenerative spinal pathology between the years 2013 and 2018 with an average follow-up of 7.8 years. We studied the lumbopelvic parameters, namely pelvic incidence and lumbar lordosis, both preoperatively and at the last follow-up. Postoperative lumbar lordosis was compared with theoretical lumbar lordosis using Le Huec's formula: LL= 0.54 x PI + 27. This comparison enabled us to define 3 groups of patients:

- Group 1: Theoretical LL - 5°≤ Postoperative LL ≤ Theoretical LL + 5

- Group 2: Theoretical LL - 5°< Postoperative LL ≤ Theoretical LL - 10°.

- Group 3: Postoperative LL < Theoretical LL - 10°.

We also carried out a study of the l5-S1 disc of all our patients preoperatively and at the last recoil, including: Calculation of l5-S1 disc height, search for osteophytes in the L5-S1 space, look for osteocondensation of the L5 and/or S1 vertebral endplates, dynamic assessment for signs of L5-S1 instability. We divided the operated patients into 2 groups according to the evolution of the disc. L5-S1 at 5 years post-op:

- Group S: patients who showed no disc degeneration or L5-S1 instability

- Group D: patients who developed disc degeneration and/or L5-S1 instability

We analyzed these parameters analytically, looking for statistical relationships. Results: In our study, 12 patients presented a disc modification and no one presented a clinical symptom. These changes correlated with pelvic incidence, but were not statistically significant. However, a statistical relationship was found with lumbar lordosis. The lower the postoperative lumbar lordosis compared with the theoretical lumbar lordosis is, the greater the adjacent L5-S1 segment disease is. Our results are in line with the literature, with a high frequency of patients developing disc degeneration with an PI-LL differential > 10°, and a statistically significant correlation was found (p = 0.0472). This could help to better establish the indications for L5-S1 capture in lumbar arthrodesis. Conclusion: Pre-op lumbopelvic parameters and planned lumbar lordosis have been the subject of numerous studies and reviews. Our study and the literature had clearly demonstrated the relationship between these parameters and the occurrence of adjacent segment disease, as well as the importance of well-planned intervention.

ID: 2549

RF207: Changes in the Oswestry Disability Index after lumbar facet joint cryodenervation in physical workers

Michal Krakowiak ¹ , Klaudia Kokot ² , Jaroslaw Dzierzanowski ¹ , Tomasz Szmuda ¹ , Piotr Zieliński ¹

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

² Students’ Scientific Circle of Neurosurgery, Neurosurgery, Gdansk, Poland

Introduction: Cryodenervation is a minimally invasive procedure in low back pain (LBP) treatment originating from facet joints. Estimates show that up to 85% of the population will experience LBP at least once in their lifetime. Peak incidence occurs between 35 and 55 years of age. LBP is the most common cause of sickness absence in UK, accounting for over 52 million working days. Occupational physical activities are suspected of causing LBP. Movements such as twisting, lifting are reported risk factors associated with LBP. Material and Methods: The study includes a retrospective analysis of physical workers who underwent cryodenervation of intervertebral joints at the Department of Neurosurgery of the University Clinical Center in the years 2017-2023 at the L4-L5 level using CRYO-S Painless device. Data analysed: age, gender, BMI, smoking, level of pain symptoms measured using the NRS (Numeric Rating Scale for Pain) and the results of the Oswestry Disability Index (ODI) questionnaire validated in Polish version 2.1. The study was approved by the Bioethics Committee for Scientific Research at the Medical University of Gdańsk in the form of resolution number NKBBN/59/2020 and the Consent of the Department of Clinical and Scientific Research at the University Clinical Center number 23/2020. Results: 41 patients were included into analysis. The mean age was 53.1 and mean BMI was 28. The number of males was n = 18, females n = 23. 46.3% of the cohort were smokers. Both NRS and ODI where statistically different after the procedure (p < 0.01), mean NRS and ODI before and after cryoneurolysis were: 7.1 and 4.2, 50.3 and 41.3 respectively. Statistically significant changes in the ODI formular were noted in: lifting, sitting, standing and sleeping (p > 0.01). Conclusion: Cryodenervation of the medial branch is an effective invasive procedure in alleviating LBP originating from lumbar facet joints. Not every aspect of the ODI questionnaire is affected by cryoneurolysis. The patient and surgeon must be aware of the elements which will be significantly affected by cryodenervation and which will remain unchanged.

ID: 2476

RF208: Clinical efficacy of screw to interbody cage length ratio in standalone lateral interbody fusion using integrated, expandable implants: a 1 year follow up study

Dean Biddau ¹ , Gregory Malham ²

¹ Queensland University of Technology, School of Biomedical Science, Brisbane, Australia,

² Epworth HealthCare, Department of Neurosciences, Richmond, Australia

Introduction: Lateral Lumbar Interbody Fusion (LLIF) is a widely used technique for treating degenerative spinal conditions. The use of standalone LLIF with expandable intervertebral cages that include integrated plate-screws (eLLIFp) has emerged as a promising approach to improve fixation and reduce the need for supplemental posterior fixation. This study assesses both of the utilisation of isotope bone scans on clinical decision making in spine surgery and the clinical outcomes and complications associated with standalone eLLIFp in a cohort of patients with at least 12 months of postoperative follow-up. Aim: To evaluate 1. the clinical effectiveness, complication rates, and correlation between the screw-to-implant length ratio and clinical outcomes in patients treated with standalone eLLIFp; and 2. the influence isotope bone scans on surgical planning. Methods: This retrospective analysis of prospectively collected data included 67 consecutive patients who underwent eLLIFp with at least 12 months of postoperative follow-up. The expandable intervertebral spacer used integrated plate-screws for fixation without additional posterior fixation. Patient demographics, diagnoses, treated levels, and complications were recorded. Diagnostic isotope bone scans were used to define systematic pathology in some cases. After the preoperative isotope bone scan, the surgical plan was then re-declared or confirmed. Clinical outcomes were assessed using pain scores for low back and leg pain, the Oswestry Disability Index (ODI), and quality of life scores (SF-12). Paired analyses were performed to compare preoperative and postoperative outcomes. Regression analysis was conducted to examine the relationship between the ratio of integrated screw lengths to intervertebral cage length and clinical improvements. Results: The cohort had a mean age of 64.4 years, and 51% were female. A total of 71 spinal levels were treated across 67 patients (n = 62, single level eLLIFp, n = 5 two level eLLIFp). By use of isotope bone scan, 16% of surgical plans were altered from the original. The most frequently treated levels were L3-4 (41%) and L2-3 (34%). The cumulative diagnoses included stenosis in 55% of patients, degenerative disc disease in 54%, spondylolisthesis in 22% and adjacent segment disease in 46%. Five complications (7.5%) were observed, including three neurological issues (one motor weakness and two sensory disturbances) and two cases of non-union requiring revision surgery. No cases of intervertebral implant subsidence were reported in our data. Significant improvements were noted in patient reported outcome measures (PROMs): low back pain decreased from 7.5 to 0.8 (p < 0.0001), leg pain improved from 5.7 to 0.6 (p < 0.0001), and ODI scores improved from 24.4 to 5.1, representing a 79% improvement (p < 0.0001). Quality of life, as measured by SF-12 physical and mental component scores, improved by 52% and 33%, respectively (both p < 0.0001). Regression analysis showed that a higher ratio of screw length to cage length was associated with improved PROMs clinical outcomes, particularly in terms of disability improvement (p = 0.0436). Conclusion: Standalone eLLIFp demonstrated excellent clinical outcomes, with significant reductions in pain, disability, and improved quality of life at 12 months postoperatively. The procedure was associated with a low complication rate, revision surgery only required in 2 cases due to non-union. Isotope bone scans within this cohort were a useful adjuvant tool to guide surgical procedure planning. A higher screw-to-cage length ratio was associated with improved disability outcomes, suggesting surgeons should aim to optimise screw-to-cage ratio when undertaking eLLIFp.

ID: 1274

RF209: Segmental decompression as a safer alternative to wide decompression in multilevel lumbar stenosis

Yoon Jae Cho ¹ , Tae Sik Goh ¹ , Jung Sub Lee ¹ , Hansol Kim ¹ , Minjun Choi ¹

¹ Pusan National University Hospital, Department of Orthopaedic Surgery, Busan, South Korea

Introduction: Recently, endoscopic spine surgery has gained popularity for minimizing soft tissue and structural damage, thus preserving natural spinal stability and reducing postoperative pain. Despite this, in multilevel spinal stenosis, wide decompression via total laminectomy remains common in open spine surgery. We hypothesize that such extensive decompression may compromise stability and increase complications. This study compares outcomes between segmental decompression and wide decompression to evaluate their impact on pain, function, and complications. Materials and Methods: From March 2016 to March 2024, 132 patients undergoing multilevel posterior decompression and fusion were enrolled. Patients were divided into segmental decompression (Group 1, 68 patients) and wide decompression (Group 2, 64 patients). Outcomes included pain (VAS), disability (ODI), health-related quality of life (SF-36), fusion rates, operative time, blood loss, and complications (cauda equina syndrome, infection). Follow-up was a minimum of two years. Results: Both groups showed significant postoperative improvements in VAS, ODI, and SF-36 scores, with no statistically significant differences between the two groups (p > 0.05). Group 1 had longer operative times (150 ± 35 minutes vs. 190 ± 40 minutes, p < 0.05), but lower blood loss (850 ± 250 mL vs. 1,050 ± 310 mL, p < 0.05). Both groups had comparable fusion rates (88% in Group 1 vs. 84% in Group 2), and Group 1 had no cauda equina syndrome cases, while Group 2 had 4 cases (p < 0.05). Conclusion: Although segmental decompression demonstrated lower blood loss and fewer complications like cauda equina syndrome, there were no significant differences in postoperative pain, functional outcomes, or health-related quality of life between segmental and wide decompression techniques. Both remain viable options for multilevel lumbar stenosis, with segmental decompression offering some advantages in terms of safety.

ID: 2170

RF210: Lordosis not maintained after single level transforaminal lumbar interbody fusion on post-operative X-rays at one year

Victoria Greenstein ¹ , Donnell McDonald ¹ , M. Umar Jawad ¹ , Norman Chutkan ²

¹ University of Arizona - Phoenix, Orthopaedic Surgery, Phoenix, United States,

² The CORE Institute, Orthopaedic Spine Surgery, Phoenix, United States

Introduction: Transforaminal lumbar interbody fusion (TLIF) can achieve significant improvement in lordosis during the intraoperative period, but it is unclear if the amount of lordosis is maintained over the post operative period. This retrospective cohort study aims to determine if the amount of intraoperative lordosis can be maintained after a single level TLIF after one year. Material and Methods: Adults undergoing single level transforaminal lumbar interbody fusion (TLIF) from 2011 to 2021 were identified by ICD codes from a single practice’s EMR. Imaging was used to measure and compare the segmental and inter-segmental lordosis at the TLIF level. Segmental lordosis was measured using the Cobb angle of the fused level. The inter-segmental lordosis was measured via the Cobb angle using the superior and inferior endplates adjacent to the interbody cage. Intra-operative lordosis was compared to the postoperative x-rays at 6 weeks, 3 months, and 1-year time periods. Results: The average difference between the segmental lordosis between intraoperative and postoperative times was calculated to be 4.96° at 6 weeks, 7.06° at 3 months and 11.92° at 1 year. The inter-segmental lordosis average difference was calculated to be 1.98°, 3.52° and 6.04° at the same time points. The average difference between the segmental lordosis at 6 weeks versus 3 months is 2.10° and 6.96° versus 1 year follow-up. The average difference between the inter-segmental lordosis at 6 weeks versus 3 months is 1.50° and 4.06° versus 1 year follow-up. Compared to 6-week radiographs, patients lost 18% of intersegmental lordosis at one-year follow-up. Conclusion: Our analysis supports that, on average, there was a loss of both segmental and inter-segmental lordosis within the first year after single level TLIF. The loss of inter-segmental is likely secondary to the interbody cage subsiding into the endplates, which in turn creates a loss of overall segmental lordosis. TLIF cages are often smaller than cages utilized for anterior and lateral approaches and also have a smaller surface area. The intraoperative imaging is done while the patient is prone, and though an effective lordosis correction may be obtained, this study suggests that it is often not maintained once the patient is upright. It also suggests that patients continue to lose lordosis within the first year post-operatively.

ID: 2849

RF211: Decreased reoperation rates for single level lumbar isthmic spondylolisthesis with anterior approach: a PearlDiver Study

Victoria Greenstein ¹ , Donnell McDonald ¹ , M. Umar Jawad ¹ , Norman Chutkan ²

¹ University of Arizona - Phoenix, Phoenix, United States,

² The CORE Institute, Phoenix, United States

Introduction: We aim to analyze the impact of different surgical approaches (anterior vs. posterior vs. anterior with posterior fusion) on 1-and 3-year reoperation rates in patients with single level fusions for lumbar isthmic spondylolisthesis (LIS) using the PearlDiver database. The PearlDiver database currently contains over 4 billion patient records obtained from the analysis of private and public insurance claims. The purpose of this study is to determine if there a difference in reoperation rates based on the approach used for single level fusions for patients with lumbar isthmic spondylolisthesis? Material and Methods: In this retrospective cohort study adult patients undergoing lumbar fusions from 2010 to 2021 were extracted from the PearlDiver database. The patients with any subsequent reoperation were identified at 1- and 3-years post-operative. Using CPT4 coding, all the patients had to have undergone lumbar fusion using anterior only, posterior only, or anterior with posterior fusion techniques who underwent only single-level procedure. Reoperation rates due to proximal junction kyphosis, spondylosis, degenerative disc disease, infection mechanical failure (Including pseudarthrosis), post-laminectomy syndrome, and stenosis were evaluated. Results: The Patient cohort included 51,709 patients: 44620 were posterior-based, 4120 were anterior only, and 2969 were anterior and posterior fusion. The incidence of reoperation rates was found for anterior vs. posterior vs. anterior with posterior fusion at the 1- and 3-year postoperative period and the relative risk for anterior only and combined anterior-posterior approach were calculated. There was a statistically significant lower reoperation rate for spondylosis and stenosis for both groups (p < .05). There were no statistically significant differences for reoperation rates for degenerative disc disease, infection, mechanical failure, and post-laminectomy syndrome were noted among approaches. Conclusion: There was a statistically significant lower reoperation rate for spondylosis and stenosis for anterior only and anterior with posterior fusion compared to the posterior only approach.

ID: 1220

RF212: OF classification reveals significant correlation to CT-Hounsfield units

Ina Moritz ¹ , Biniam Bekele ¹ , Tabea Miron ¹ , Steffen Reissberg ² , Yu-Mi Ryang ¹

¹ Helios Klinikum Berlin Buch, Neurosurgery, Berlin, Germany,

² Helios Klinikum Berlin Buch, Neuroradiology, Berlin, Germany

Background: The gold standard for diagnosing osteoporosis is dual-energy X-ray absorptiometry (DEXA) and the resulting T-score. However, studies have shown that this method is only reliable to a limited extent. A less expensive and widely available method is the measurement of Hounsfield units (HU) on CT. This study analysed the correlation of DEXA-based T-scores and CT Hounsfield units with the severity of osteoporotic fractures using the OF classification. Methods: From 2019 to 2024, 350 patients (with osteoporotic fractures of the spine) were examined. All patients underwent CT imaging of the lumbar spine and 170 patients underwent a DEXA scan. 170 patients were analysed via DEXA scan (n = 170 with T-score of the lumbar spine, n = 123 with T-score of the hip, n=113 with T-score of the femur). Only patients who received both examinations were analysed. HU and T-scores were compared with the OF classification of these patients. The HU cut-off value for an osteoporotic fracture was set at < 90 based on the new modified AO score for osteoporotic fractures. The parameters were statistically analysed using the Kruskal-Wallis test. Results: A total of 263 fractures were evaluated in 170 patients. Most patients (34%) showed OF 3 fractures, 31% OF 4 fractures, 21% OF 2, 12% OF 5 and 2% OF1 fractures. After analysing the OF classification, a significant successive decrease in HU (p = 0.036) was observed according to the severity of the osteoporotic fracture (OF1: 91.28; OF2: 86.61; OF3: 82.14; OF4: 75.78; OF5: 68.3). The DEXA scan shows the following results with regard to OF classification (lumbar spine T-score): OF1: -1.8; OF2: -2; OF3: -1.9; OF4: -2.1; OF5: -1.95; with no significant correlation for the T-score in the DEXA scan of the lumbar spine (p = 0.86), the hip (p = 0.77) or the femur (p = 0.96). Conclusion: In our study, we demonstrated a significant correlation of HU with the severity of OF. A prediction for surgical therapy can be made based on the HU. Even though the DEXA scan is still the gold standard, HU seems to be better suited to detect manifest osteoporosis.

ID: 1968

RF213: The role of spinopelvic parameters in clinical and functional outcomes following lumbar fusion surgery

Renato Pereira ¹ , Henrique Félix ² , Maura da Silva Cambango ¹ , Pedro Ribeiro ¹ , Nubélio Duarte ¹ , Renata Marques ¹

¹ Hospital de Braga, Braga, Portugal,

² University of Minho, School of Medicine, Braga, Portugal

Introduction: The influence of spinopelvic parameters on clinical and functional outcomes has been widely studied in spinal fusion surgeries involving long segments. However, it is also important to examine the effect of these parameters in fusion surgeries of short segments. We aimed to evaluate the spinopelvic parameters in patients undergoing lumbar interbody fusion and to analyse the correlation with clinical and functional indicators. Furthermore, to determine whether the variables related to the patient, diagnosis and surgery have an influence on the clinical and functional indicators obtained. Material and Methods: A longitudinal prospective study was carried out between January 2021 and December 2023, which included patients with lumbar stenosis with and without spondylolisthesis who underwent lumbar interbody fusion. Data was collected about the patient, the diagnosis and the surgery. Functional results were assessed using the Oswestry Disability Scale (ODI), while clinical results were assessed using the Visual Analogue Scale for low back pain and lower limb pain. Spinopelvic parameters were measured on an extra-long X-ray of the spine. Functional and clinical results as well as spinopelvic parameters were measured before surgery and 6 months afterwards. Results: There was a clinical and functional improvement after surgery (p < 0.001). The variables lumbar stenosis with spondylolisthesis and 2-level fusion showed less improvement post-surgery (p < 0.05). The L4-S1 parameter showed an increase postoperatively (+3.81 ± 10.4; p = 0.022). However, there was no correlation between the increase in L4-S1 and the post-operative clinical and functional results. Conclusion: There was a significant improvement in clinical and functional results, but this was not related to the increase in L4-S1 or variation of other spinopelvic parameters.

ID: 1932

RF214: Trajectory of pre-operative bone mineral density measured in Hounsfield units prior to thoracolumbar fusion predicts post-operative proximal junctional kyphosis and failure

Yevgeniy Freyvert ¹ , August Avantaggio ¹ , Jonathan Pluemer ¹ , Anna Gorbacheva ¹ , Zac Tataryn ¹ , Jerry Robinson ¹ , Jared Cooke ¹ , Nathan Pratt ¹ , Julius Gerstmeyer ¹ , Clifford Pierre ¹ , Amir Abdul-Jabbar ¹ , Rod Oskouian ¹ , Jens Chapman ¹

¹ Seattle Science Foundation, Seattle, United States

Introduction: Proximal junctional kyphosis (PJK) and proximal junctional failure (PJF) are common complications following thoracolumbar spinal fusion with significant adverse cost and patient satisfaction consequences. A definitive method for preventing PJK has not yet been identified, but various strategies have been proposed to optimize biomechanics at the uppermost instrumented vertebra (UIV) and UIV+1. Poor bone mineral density (BMD) is the most universally recognized medical risk factor for PJK. Dual-Energy X-ray Absorptiometry (DEXA) scans have long been the gold standard of osteoporosis screening but are known to overestimate BMD in the vertebrae of patients with adult spinal deformity. Opportunistic CT, with Hounsfield units (HU) measured in the trabecular bone, is an appealing method to gauge BMD when treating spinal deformity as low HU measurements of vertebral bodies in the lumbar spine have been linked to PJK. In this study, we aim to evaluate whether a trend of declining BMD measured with opportunistic CT, irrespective of absolute bone density, is associated with PJK in long segment thoracolumbar fusion. Material and Methods: An IRB-approved single-institution retrospective cohort study of consecutive spinal fusions from January 1^st, 2015 through April 30^th, 2021 was performed. Patients undergoing five or more levels of fusion in the thoracolumbar spine for whom pre- and peri-operative CT scans including UIV and UIV+1 were included and divided into two cohorts based on available imaging studies. Vertebral BMD was measured using HU and BMD velocity (rate of change) was calculated between imaging studies. Sagittal Cobb angle above the construct was measured on a post-op x-ray to determine PJK while PJF was identified with a combination of clinical and imaging factors. Statistical analysis was performed using chi-square test, logistic regression, and bivariable and multivariable analyses. Results: Mean BMI values for PJK and PJF patients were lower at 27.58 and 28.93 kg/m³, respectively, than the 30.90 kg/m³ seen in patients without proximal junctional pathology. The inverse correlation between BMI and PJK/PJF approaches significance with a p-value of 0.08. There was no significant difference in smoking history or rates of osteoporosis and osteopenia between patients with and without PJK/PJF. Across both cohorts, mean follow up time is highest for PJK patients and lowest for PJF patients. Pre- and peri-operative BMD measurements are higher in patients without PJK/PJF almost universally, with the exception of only pre-operative BMD at the UIV+1 in cohort 1. A negative trend in peri-operative BMD at the UIV +1 was significantly associated with nearly 5 times the odds of experiencing PJK/PJF. Conclusion: A trend in BMD can be established using HU on opportunistic CT using multiple time-data points. This study’s results show a statistically significant correlation between rates of PJK/PJF and a negative trend in BMD at the UIV + 1, pre-operative BMD changes at the UIV, and peri-operative BMD changes at the UIV + 1. Reducing rates of PJK will lower re-operation risks and hospital costs in addition to improving patient outcomes.

RF13: DIAGNOSTICS AND EPIDEMIOLOGY IN SPINE

ID: 1605

RF 215: Quantitative morphological apical intervertebral disc characteristics as predictors of curve progression in adolescents with scoliosis

Conor Boylan ¹ , Morgan Jones ^2,3 , Siddhant Kapoor ² , David Marks ² , David Polly ⁴ , Arin Ellingson ⁴ , Joe Jan Gouda ²

¹ University of Edinburgh, Edinburgh, United Kingdom,

² The Royal Orthopaedic Hospital Birmingham, Birmingham, United Kingdom,

³ Birmingham Children's Hospital, Birmingham, United Kingdom,

⁴ University of Minnesota, Minneapolis, United States

Introduction: Quantitative disc analysis is a promising method to assess intervertebral disc morphology in patients with adolescent idiopathic scoliosis (AIS) with a higher accuracy and reproducibility than currently used subjective measures. Furthermore, when combined with other patient and pathological characteristics, it may improve our ability to predict disease progression and need for early surgical intervention. This project explored morphological characteristics of apical discs in patients with AIS and a statistical model was developed to predict need for surgery. Material and Methods: This was a retrospective case-control study at a single tertiary referral centre for spinal deformity surgery, where it is routine practice for patients to have MRI scoliosis protocol performed at baseline presentation to spinal deformity clinic. Patients with appropriate imaging were randomly selected, 50 of which required surgery within 5 years and 50 of which did not. Data on nucleus pulposus (NP) and disc signal intensity, NP area, NP location, transition zone slopes and disc asymmetry indices were calculated using a novel script developed by researchers at the University of Minnesota. Data on Cobb angle, Lenke type, Risser stage, SRS-22 scores, and other baseline characteristics were also collected. Univariable statistical methods were used to compare individual characteristics between cohorts and backward input binary logistic regression was used to develop an optimal model to predict which patient would proceed to surgery based on their baseline data. Results: Patients in the surgical cohort were younger (p = 0.007), had larger Cobb angles (p < 0.001), and were more likely to have a double thoracic curve type (p = 0.001). Surgical patients also had greater mean NP signal intensity (p = 0.008), more well-defined concave transition zones (p = 0.008) and an overall greater coronal transition zone symmetry (p = 0.036). Surgical patients were more likely to have an apical disc in the lower thoracic region and non-surgical in the thoracolumbar/lumbar region (p = 0.030). Of the 50 patients that underwent surgery, the majority underwent posterior correction (88.0%). SRS-22 scores did not differ significantly between cohorts. A model was developed to predict which patients would require early surgical intervention with 85.0% accuracy (p < 0.001, AUC 0.904), which is greater than when using Cobb angle alone. Predictors included were Cobb angle, age, coronal asymmetry index, NP signal intensity, Lenke type, and NP location (weighted) in the coronal plane – with the first three being most impactful in the model. Conclusion: This study has demonstrated the use of detailed quantitative disc morphological analysis in a real clinical setting and has identified several factors predictive of need for early surgery in patients with AIS, many of which have not been examined with this level of scrutiny before. It indicates the value of detailed disc morphological analysis in a clinical setting and will form the basis of future research which aims to improve our ability to predict scoliotic patients that will require surgical intervention at the earliest possible timepoint.

ID: 1216

RF216: Sex differences in epidemiology, treatment, and outcomes of traumatic spinal fractures: a retrospective cohort study and scoping review

Anna Veenstra ¹ , Sebastian Bigdon ¹ , Christoph Albers ¹ , Sonja Häckel ^1,2

¹ Inselspital, University Hospital Bern, Department for Orthopaedic Surgery and Traumatology, Bern, Switzerland,

² University Bern, Graduate School of Health Sciences, Bern, Switzerland

Introduction: Spinal injuries are common in young men injured by high-energy trauma such as traffic accidents or falls, whereas older women are more prone to fractures associated with osteoporosis. Despite these recognized sex differences in spinal fractures, the consequences such as treatment and outcomes are unknown. The aim of this study is to investigate sex differences in the epidemiology of spinal trauma. In addition, we conducted a literature review to answer the question of whether there is a sex-specific difference in the treatment and outcomes of spinal fractures and in enrollment in clinical trials. Material and Methods: A retrospective cohort study of traumatic vertebral fractures over 10 years at a Level-1 trauma center was conducted to examine epidemiologic sex differences (incidence, fracture classification, treatment) and bone quality (Hounsfield units on CT). A systematic search was also performed for randomized controlled trials, and prospective and retrospective studies that included patients with acute spinal fractures. Studies involving pathologic vertebral fractures or osteoporosis were excluded. The PCC (Population, Concept, Context) framework was used to analyze the inclusion of sex as a variable. Results: Among 2,473 patients with traumatic vertebral fractures, 1,615 were male and 858 were female. Statistically significant differences were found in the localization of fractures: women were more frequently injured in the occipitocervical (C0-C2) and thoracolumbar (T10-L2) regions, while men had more frequent injuries in the cervical spine (C3-C7). Men were 1.25 times more likely than women to receive surgical treatment (p = 0.013, OR: 1.25 [95% CI 1.04-1.5]). The literature review indicated that women had higher disability scores on subjective measures, such as the Oswestry Disability Index, even with similar radiologic outcomes. Women were also more likely to receive conservative treatment. Conclusion: Men experience traumatic spinal injuries more frequently, particularly in the cervical spine, and are more likely to undergo surgery. The literature review underscores the need for further research on sex-specific outcomes to refine treatment approaches and enhance clinical care for both sexes.

ID: 538

RF217: Lumbar range of motion using the Wolfson Schober Test

Oded Hershkovich ¹ , Raphael Lotan ¹

¹ Edith Wolfson Medical Centre, Orthopedics, Spine, Holon, Israel

Introduction: Lumbar range of motion (ROM) is a critical component of spinal function and is often affected by age and sex. This study aimed to evaluate the variations in lumbar ROM across different age groups in a healthy adult population and to determine the influence of sex, height, weight, and body mass index (BMI). Methods: 208 subjects (106 males, 102 females) were recruited and stratified into age groups from the 20s to 60s and older. Lumbar ROM was measured using WMST (Wolfson Modified Schober Test). Data analyzed for flexion, extension, and total ROM. Linear regression examined the predictors of lumbar ROM. Results: The study found a progressive decline in lumbar flexion and total ROM with age in both sexes. Male and female height and weight differed significantly, but these differences did not influence lumbar ROM. Age was the only significant predictor of lumbar flexion, with no significant impact of weight and BMI on ROM. Extension measurements were inconsistent and did not show a clear pattern across age groups. Conclusions: Age-related changes in lumbar ROM were consistent with known physiological changes within the spine. Despite physical differences in height and weight, the lumbar spine ROM was similar between sexes, highlighting the influence of age over sex in lumbar motion. Lumbar ROM decreases with age, with flexion affected more than extension, not significantly influenced by weight or BMI. These findings underscore the importance of considering age in assessing lumbar spine health and flexibility and the role of WMST in assessing lumbar ROM.

ID: 921

RF218: Impact of provider variability and patient factors in preoperative screening for osteoporosis in adult deformity patients at a tertiary academic center

Avionna Baldwin ¹ , Zodina Beiene ² , Aboubacar Wague ³ , Ashraf El Naga ¹ , David Gendelberg ¹ , Anna Filley ¹ , Sigurd Berven ¹

¹ University of California, Orthopedic Surgery, San Francisco, United States,

² Orthopedic Trauma Institute, San Francisco, United States,

³ University of California, San Francisco, United States

Introduction: In the adult spine deformity population, research has established osteoporosis as a risk factor for mechanical failure after spine instrumentation. While orthopedic trauma initiatives aim to increase screening for osteoporosis after fragility fracture, there is currently no work assessing the frequency and determinants of screening for osteoporosis using the gold standard Dual-Energy X-ray Absorptiometry (DXA), within the spine deformity population. Screening for osteoporosis can reduce disparities in healthcare by identifying risk factors and creating standardized practices in care. This study aims to report the frequency of preoperative bone health measurements in adult spinal deformity patients prior to elective multilevel reconstructive surgery, and to identify risk factors for lacking preoperative assessment of bone health. Material and Methods: Retrospective study design of adult spine deformity patients 65 and older undergoing at least six levels of fusion between 2016-2018. Electronic medical record was used to collect patient demographics and perioperative data. The two cohorts (DXA vs no DXA) were compared using statistical analysis and significant variables identified (p value < 0.05). Multivariable logistic regression was performed to identify any independent associations while accounting for potential confounders. Results: 372 total patients- 227 patients (61.0%) underwent preoperative DXA and 145 (39.0%) had no DXA. Mean age (yrs) was 72.13 (SD 4.89) and 72.46 (SD 5.13), respectively. Females predominated in the DXA group (159, 72.6%) and were significantly more likely to have DXA than males (p < 0.001). There was no significant difference in terms of ethnicity. Sub-grouping comparing White, Asian, and the remaining underrepresented minorities (URM) showed a significant difference in screening rates (p = 0.042), specifically on post hoc analysis a trend toward no DXA in the URM group (p = 0.052). The neurosurgery service had statistically significant higher rates of DXA (152, 72.7%) compared to the orthopedic surgery service (75, 46.0%) (p < 0.001). Patients undergoing thoracic-sacral surgery, over 12 or more levels, were significantly more likely to have undergone DXA (p = 0.008; p = 0.004). There was a statistically significant difference in DXA rates among the 12 providers (range, 91.7% to 23.1%) (p < 0.001). The providers were then grouped into high vs low screeners based on the cohort threshold of 61% screening. On multivariate analysis, sex (female), screener group (high compared to low), and regions of surgery (thoracic and thoracic-sacral compared to cervical) were independently associated with DXA screening (p < 0.001; p < 0.001; p = 0.039; p = 0.025). Female sex, the high screener group, and thoracic and thoracic-sacral regions had 6.08 (95% CI: 3.35 - 11.03), 12.40 (95% CI: 5.56 - 27.65), 15.14 (95% CI: 1.15 - 199.25), and 2.42 times (95% CI: 1.12 - 5.21) higher odds of undergoing screening. Conclusion: Osteoporosis is a major risk factor of mechanical complication in the adult deformity population, making preoperative bone health assessment crucial for elderly patients undergoing multilevel reconstructive surgery. Our findings reveal that both spine surgeon practices and patient demographics, particularly gender and ethnicity, significantly impact the likelihood of preoperative osteoporosis screening. Standardizing protocols across surgical providers to identify and screen high-risk groups prior to spine surgery could optimize outcomes. Future research should examine spine surgeon motivations, attitudes, and barriers to preoperative screening.

ID: 1821

RF219: High variability of vertebral artery anatomy: implications for anterior cervical surgery

Gonzalo Alberto Moros Daza ¹ , Bujung Hong ¹ , Eder Florian ² , Ansgar Berlis ³ , Christoph Maurer ³ , Ina Konietzko ¹ , Ehab Shiban ¹

¹ Lausitz University Hospital, Neurosurgery, Cottbus, Germany,

² University of Augsburg, Faculty of Medicine, Augsburg, Germany,

³ University of Augsburg, Neuroradiology, Augsburg, Germany

Introduction: The anterior cervical spinal approach offers relatively safe access for a wide range of cervical pathologies. Although rare, injury to the vertebral artery (VA) can lead to serious complications. Normally, the VA is protected within the transverse foramen; however, anomalies such as elongation and loop formation are described. These variations may increase the risk of vascular injury during the surgery. The purpose of this study is to analyze anatomical variations of VA. Material and Methods: We conducted a retrospective analysis of CT angiograms of the head and neck in 1,001 patients, with data collected between 2018 and 2020 from Augsburg University Hospital, Germany. All images were obtained using a 2nd generation dual-source CT scanner (SOMATOM Definition FLASH, Siemens Healthcare, Forchheim, Germany), with 128 slices at 0.6 mm and subsequent 3D reconstruction. Elongation was defined as a deviation of one or both VA from their normal course within the transverse foramen. The presence of elongation, its laterality, anatomical location, and correlations with age and sex were documented. Results: VA elongation was observed in 145 (14.5%) patients, of which 71 patients had isolated left-sided anomalies, 39 had isolated right-sided anomalies, and 35 had bilateral anomalies. The most common level of elongation was C2/3 (n = 77), followed by C3/4 (n = 69), C4/5 (n = 31), and C5/6 (n = 10). No loops were identified at the C1/2 or C6/7 levels. Conclusion: The incidence of VA elongation in our cohort was very high. Preoperative evaluation of VA anatomy is essential to avoid vascular injury during anterior cervical spinal surgery.

ID: 378

RF220: Radiological assessment of lumbar fusion status: which imaging modality is best assessing non-union in lumbar spine pseudoarthrosis?

Enrique Gonzalez Gallardo ^1,2 , Ian A. Buchanan ¹ , Kingsley O. Abode-Iyamah ¹ , Eric W. Nottmeier ¹ , Selby G. Chen ¹ , Stephen M. Pirris. ¹ , Oluwaseun O. Akinduro ¹ , Juan Pablo Navarro Garcia de Llano ¹ , Jesus Emiliano Sanchez Garavito ¹ , Justyna O. Ekert ¹ , Michaelides Loizos ^1,3 , Jorge Rios Zermeno ¹ , Harshvardhan Iyer ¹ , Alfredo Quinones Hinojosa ¹ , Rodrigo Navarro- Ramirez ¹

¹ Mayo Clinic, Neurosurgery, Jacksonville, Florida, United States,

² Lic. Adolfo Lopez Mateos Regional Hospital, Department of Neurosurgery and Spine Surgery, Mexico City, Mexico,

³ Lebanese American University, Gilbert and

Rose-Marie Chagoury School of Medicine, Byblos, Lebanon

Introduction: Lumbar Disc Degenerative Disease (LDDD) is the leading cause of low back pain and disability globally, particularly in the aging population. Lumbar Interbody Fusion (LIF) surgery is the standard treatment for a variety of lumbar spine conditions, including degenerative, traumatic, infectious, and tumoral pathologies. Despite its widespread use, LIF can lead to complications such as pseudoarthrosis, a condition characterized by failed spinal fusion and incomplete osseous bridging over a year post-surgery. This systematic review examines current radiographic techniques used to assess lumbar fusion outcomes. Material and Methods: We followed PRISMA guidelines to conduct a systematic review of PubMed, Embase, Google Scholar, and Cochrane Library databases, focusing on articles in English. We included studies involving patients aged 18 and older who had undergone lumbar interbody or posterolateral fusion with at least one year of radiographic follow-up. The primary outcomes analyzed were sensitivity, specificity, and the correlation of radiographic findings with surgical exploration, the gold standard for fusion assessment. Results: Thirteen studies, published between 1989 and 2019, met the inclusion criteria. These studies primarily originated from North America and Europe, with a majority being retrospective. The review covered a total of 715 patients, with mean ages ranging from 42 to 78 years. Surgical approaches were predominantly open posterior. The reviewed studies employed various imaging techniques, including Plain Radiographs, Dynamic or Flexion-Extension Radiographs, Computed Tomography (CT), Single Proton Emission-CT (SPECT), Bone Scintigraphy, Magnetic Resonance Imaging (MRI), and Ultrasonography. CT was the most frequently used and showed a wide range of sensitivity (53%-100%) and specificity (78%-96.7%). Flexion-extension radiographs, while common, demonstrated high variability in sensitivity and specificity, making them less reliable, especially in the presence of lumbar instrumentation. MRI and ultrasonography were the least employed techniques, with limited data supporting their use. Conclusion: Current imaging techniques for assessing lumbar fusion vary widely in reliability and accuracy. CT scans, with advanced reconstruction techniques, are the most dependable, but no single modality has been universally endorsed. Further research is needed to standardize imaging criteria for better clinical outcomes in LIF patients.

ID: 2691

RF221: Spine deformity patients with spinal cord stimulators and intrathecal drug delivery devices do not have greater opioid use

Alexandra Dionne ¹ , Kurt Holuba ¹ , Riley Sevensky ¹ , Justin Reyes ¹ , Roy Miller ¹ , Fthimnir Hassan ¹ , Cole Morrissette ¹ , Yong Shen ¹ , Matan Malka ¹ , Mark M. Herbert ¹ , Gabriella Greisberg ¹ , Joseph Lombardi ¹ , Zeeshan Sardar ¹ , Lawrence Lenke ¹

¹ Columbia University Medical Center, New York, United States

Introduction: Chronic opioid use can have serious negative effects on spine surgery patients, and the risks are especially high for the adult spinal deformity (ASD) population. Spinal cord stimulators (SCSs) and intrathecal drug delivery devices (IDDDs) are used as alternative treatments for chronic back pain, but very little is known about their effect on chronic opioid use after subsequent spine surgery. This study aims to determine if ASD patients with a SCS or IDDD have more chronic opioid consumption or worse surgical outcomes than a matched cohort. Methods: We conducted a retrospective matched comparison of implanted (SCS [n = 11] or IDDD [n = 3]) and non-implanted ASD patients (n = 40) who underwent corrective spine surgery at a single center. We evaluated their intraoperative characteristics, long-term postoperative complications, radiographic correction, and chronic opioid use, measured as use on more than 50% of days for greater than 6 months pre- or postop and total morphine mg equivalents (MME) and MME per dose. Results: We found no difference in the rate of chronic opioid use between the implanted and non-implanted ASD cohort: 6m preop: 50% (n = 7) vs 40% (n = 16), admission: 71% (10) vs 45% (18), 6 m postop: 64.3% (9) vs 32.5% (13), FFU: 64.3% (9) vs 37.5% (15), p > 0.05. Similarly, there was no difference in Total MME: 6m preop: 101.3 ± 177.8 vs 37.3 ± 89.4, admission: 68.2 ± 77.8 vs 45.3 ± 129.9, 6m postop: 59.8 ± 83.1 vs 20.8 ± 46.9, FFU: 51.2 ± 68.7 vs 31.1 ± 55.5, p > 0.05 for all. There was also no difference in MME per dose: 6m preop: 33.9 (49.2) vs 21.1 (58.2), admission: 55.1 (85.6) vs 20.4 (59.8), 6 m postop: 18.3 (19.2) vs 11.1 (39.6), FFU: 19.7 (25.8) vs 8.9 (15.7), p > \0.05 for all. We observed a trend of higher values in the implanted group at all timepoints. Implanted patients had higher OR time (implanted: 734.9 [103.4] vs non-implanted: 637.2 [147.8] min, p = 0.0272), intraoperative blood requirement (2.1 [1.6] u pRBCs vs 1.1 [1.5] u, p = 0.0500), and rate of dural tears (42.9% (6/14) vs 15% (6/40). Otherwise, their surgical outcomes, long-term complication rates and revision rates were equivalent. Conclusion: This study indicates that implanted ASD patients are not at increased risk for chronic opioid use and that they overall do not have worse postoperative compilation rates than non-implanted patients. However, the trends in the data support the need for further research in larger cohorts to ensure adequate power. High revision rates and prolonged postoperative opioid use illustrate the increased risk for chronic opioid use in the ASD population as a whole.

ID: 1532

RF222: Cervical paraspinal muscle parameters are associated with bone mineral density as measured by quantitative computed tomography and vertebral bone quality in preoperative patients

Bruno Verna ¹ , Artine Arzani ¹ , Thomas Caffard1 ² , Lukas Schönnagel ³ , Krizia Amoroso ¹ , Erika Chiapparelli ¹ , Jiaqi Zhu ⁴ , John Carrino ⁵ , Jennifer Shue ¹ , Andrew Sama ¹ , Frank Cammisa ¹ , Federico Girardi ¹ , Alexander Hughes ¹

¹ Hospital for Special Surgery, Spine Care Institute, New York, United States,

² University of Ulm, Department of Orthopedic Surgery, Ulm, Germany,

³ University of Berlin, Center for Musculoskeletal Surgery, Berlin, Germany,

⁴ Hospital for Special Surgery, Department of Epidemiology and Biostatistics, New York, United States,

⁵ Hospital for Special Surgery, Department of Radiology and Imaging, New York, United States

Introduction: Osteoporosis and sarcopenia are prevalent conditions among elderly patients and often coexist. Previous studies demonstrated a positive association between lumbar paraspinal muscle functional cross-sectional area (fCSA) and volumetric bone mineral density (vBMD) measured with quantitative computed tomography (QCT). The relationship between cervical paraspinal muscle parameters and cervical bone mineral density has not been investigated. Another imaging method for assessing site specific bone quality is vertebral bone quality (VBQ). This study aims to characterize the association between paraspinal musculature at C3 and cervical vBMD and quality measured with QCT and VBQ. Material and Methods: Patients with preoperative cervical MRI and CT imaging who underwent anterior cervical discectomy and fusion between 2015 and 2018 were reviewed. Muscles at C3 were categorized into 4 functional groups: sternocleidomastoid group, anterior group, posteromedial and posterolateral group. For all groups, the cross-sectional area (CSA), functional CSA (fCSA), and percent fat infiltration (FI) were measured. QCT measurements and VBQ scores of the cervical vertebral bodies were performed using prior established methodologies. Multivariable linear regression analyses adjusted for age, sex, and BMI were performed. The Benjamini-Hochberg procedure was applied to adjust p-values. Results: A total of 100 patients (median age 56.5 years; 38 females) were included. Regarding QCT, a high BMD value indicates greater bone strength. For VBQ, a high score indicates high fat content of the bone, meaning that high VBQ scores indicate lower bone quality and low VBQ scores indicate better bone quality. After adjusting for age, gender and body mass index and adjusting p-values with the Benjamini-Hochberg procedure, regression analysis demonstrated a significant negative association between fCSA of the anterior group with VBQ scores from C2 to T1. Additionally, regression analyses demonstrated a significant positive correlation between CSA of the posteromedial group with QCT measured on C1 and C3. Conclusion: This study is the first to report significant correlations between bone mineral density, quality and cervical paraspinal muscles. These findings also demonstrate the potential clinical utility of cervical muscle and BMD analysis as part of a preoperative assessment.

ID: 148

RF223: The impact of prior knee or hip arthroplasty on Oswestry Disability Index two years after lumbar surgery

Jan Hambrecht ¹ , Paul Koehli ¹ , Erika Chiapparelli ² , Krizia Amoroso ^1,2 , Jiaqi Zhu ² , Ali Guven ¹ , Gisberto Evangelisti ¹ , Marco Burkhard ¹ , Koki Tsuchiya ¹ , Roland Duculan ¹ , Jennifer Shue ¹ , Carol Mancuso ¹ , Andrew Sama ¹ , Frank Cammisa ¹ , Federico Girardi ¹ , Alexander Hughes ¹

¹ Hospital for Special Surgery, Department of Orthopaedic Surgery, New York City, United States,

² Hospital for Special Surgery, New York City, United States

Introduction: The loss of mobility and musculoskeletal discomfort caused by degenerative diseases significantly reduces the quality of life, especially for the aging population. As a result, the number of hip and knee replacements and spine surgeries is increasing. Managing spinal conditions along with hip or knee osteoarthritis presents challenges in treatment decisions and may result in ongoing postoperative complaints. While several studies have examined the impact of pre-existing spinal conditions and prior spinal fusion surgery on arthroplasty outcomes, few have examined the impact of arthroplasty on lumbar spine surgery outcomes. This study aims to evaluate the influence of prior total hip arthroplasty (THA) and total knee arthroplasty (TKA) on Oswestry Disability Index (ODI) two years after elective lumbar surgery. Material and Methods: A secondary analysis of a prospective study of patients undergoing lumbar surgery for degenerative conditions was conducted. Patients with a two-year ODI follow-up were included. ODI was prospectively assessed pre- and postoperatively. Patients without ODI-assessment were excluded. Differences in pre- and postoperative ODI were evaluated, and patients were categorized based on ODI-improvement. Statistical analyses included Mann-Whitney-U-test, univariable logistic regression, and multivariable logistic regression adjusted for age, sex, and BMI. Results: A total of 385 patients with age 65 ± 10 years (57% female) were included. Prior to lumbar surgery, there were 46 patients (12%) with a history of isolated THA, 34 (9%) patients with a history of isolated TKA and 11 (3%) patients with TKA and THA. ODI improvement was achieved in 91% of patients. 36 patients (9%) showed no ODI improvement two years after lumbar surgery. Patients with ODI non-improvement postoperatively were predominantly male (64%, p ≤ 0.001). A history of combined TKA and THA was significantly associated with ODI non-improvement (OR 9.9, 95% CI 2.53-38.3, p = 0.001) compared to patients without prior arthroplasty. Prior isolated TKA also tended to be a risk factor for ODI non-improvement, although not statistically significant (OR 2.8, 95% CI 0.9-7.4, p = 0.052). A history of THA only was not significantly associated with ODI non-improvement (OR 1.7, CI 0.5-4.5, p = 0.339). 23% of the patients received only a decompression, and 77% underwent fusion and decompression surgery. Conclusion: Patients with a prior history of concomitant TKA and THA have higher odds for ODI non-improvement two years after elective spinal surgery. These findings imply that coexisting, musculoskeletal degeneration of the spine and lower extremity might have a negative effect on a patient’s potential for improvement following lumbar surgery. The results of this study underscore the connection not only between the hip, but also the knee and the spine, also referred to as the knee-spine syndrome.

ID: 958

RF224: One size doesn’t fit all: ergonomics of instruments routinely used in spinal surgery

Susana Núñez-Pereira ¹ , Cristina Lloret-Peiró ² , Margalida Hernández-Vicens ²

¹ Vall d'Hebron University Hospital, Spine Surgery Unit, Barcelona, Spain,

² Vall d'Hebron University Hospital, Orthopaedics and Trauma Surgery, Barcelona, Spain

Introduction: Most instruments used during spinal surgery are produced in a single standard size, but surgeons' hand sizes can vary between 6 and 8.5 inches. Surgeons with smaller hands may struggle to apply sufficient force to instruments they cannot grip properly, leading to underperformance, inaccuracy, and potential injuries. We conducted a biomechanical study measuring grip strength (GS) in different positions to highlight the need for a range of instrument sizes. Materials and Methods: This biomechanical study involved orthopedic surgeons from a single European center. Demographic data and hand anthropometric measurements (length of palm (LP), length of hand (LH), and wrist circumference (WC)) were recorded. All participants underwent three grip strength measurements in two different positions (ergonomic (EP) and forced position (FP)) using a calibrated Jamar hydraulic dynamometer (JLW Instruments, Chicago, IL). Mean values of the three measurements were used. Results were analyzed using Spearman correlations, one-way ANOVA, and multivariate regression. Results: Fifty-nine participants (33.8% female, mean age 38.2). Hand size distribution differed by gender, 75% of females had a hand size of 7 inches or smaller, whereas 81% of males had a hand size greater than 7 (p < 0.0001). Statistically significant correlations were found between hand size, all anthropometric hand measures, and GS. Higher correlations were observed in FP (Hand size r = 0.713, LP r = 0.658, LH r = 0.860, WC r = 0.749, EP = 0.929; all p < 0.01). GS progressively increased with hand size: size 6.5 (EP 21.4, FP 13.2), size 7 (EP 33.0, FP 23.3), size 7.5 (EP 34.4, FP 26.4), size 8 (EP 40.0, FP 31.4), size 8.5 (EP 60.0, FP 49.1). Individuals with smaller hands (≤ 6.5 inches) lost 36.8% of their GS when shifting from EP to FP, compared to 14% in those with larger hands (≥ 7 inches) (p < 0.0001). There was a significant correlation between hand size and GS loss (rho = 0.642). Multivariable analysis showed that GS in FP was significantly associated with GS in EP, hand size, and LH, with an r² of 0.951. The FP distance was 10.5 cm, while the grip distance of the Kerrison rongeurs in our institution ranged between 9.5 and 11.5 cm. Conclusion: Although this study is limited by high collinearity among variables, it demonstrates that surgeons with smaller hands (predominantly females in our setting) are at a disadvantage when using common instruments like Kerrison rongeurs. Awareness of these disadvantages should encourage policies that offer more instrument size options to accommodate the ergonomics of different hand sizes.

ID: 824

RF225: The first years of practice of young spine surgeons in Latin America

Jose Dangond ¹ , Alfredo Guiroy ² , Omar Marroquin Herrera ³ , Guisela Quinteros Rivas ⁴ , Pedro Henrique Couri ⁵ , Fernando Alvarado Gómez ⁶ , Nelson Astur ⁷

¹ Hospital Serena del Mar/Clinica Campbell, Orthopedicts, Spine, Cartagena/Barranquilla, Colombia,

² Hospital Español de Mendoza, Mendoza, Argentina,

³ Hospital MAC, Puebla, Mexico,

⁴ Hospital Regional de Talca, Talca, Chile,

⁵ Hospital Albert Einstein, Spine, Sao Paulo, Brazil,

⁶ Fundacion Santa Fe De Bogota, Orthopedicts, Spine, Bogota, Colombia,

⁷ Hospital Albert Einstein, Orthopedicts, Spine, Sao Paulo, Brazil

Introduction: The increasing demands placed on spine surgery residents, along with the constant advancements in technology whose application calls for prior preparation, have led to noticeable gaps in education and training processes. Factors such as uneven levels of experience, the lack of standardization in programs and fellowships, varying degrees of course director support, and inconsistent learning curves pose potential challenges to the training of spine surgeons. Material and Methods: A multiple-choice questionnaire was sent to AO Spine Associate Fellows who completed their studies within the past 5 years. This survey aimed to gather information on their professional activities during the initial 3 years of practice following their fellowship. By comparing the responses and activities undertaken by surgeons on a country-by-country basis, it will be possible to describe and analyze the local and regional outcomes in Latin America. Results: The countries with the highest participation in the AO Spine Fellowship program are currently Argentina (30.7%), Brazil, and Colombia (28.21%). Participants aged 36 to 45 are the age group with the highest engagement (30.7%). Among program participants, 75% are orthopedists. Other notable findings include that 95% of respondents have greater experience and feel more comfortable working in degenerative spine pathology. Conclusion: Currently, junior fellows in the AO Spine program report a high level of comfort with the initiative. However, our study reveals valuable insights that can contribute to its improvement. It is worth noting that there is a clear preference for the standard posterior approach persists. Nevertheless, there is a growing interest among junior surgeons in endoscopic and minimally invasive techniques. This study serves as a gateway to essential data for future studies and the enhancement of the Fellowship education program in Latin America.

ID: 2265

RF226: Morphological findings of the sub-axial cervical spine among different continents and populations and its implication on pedicle cervical screw placement: a systematic review and metanalysis

Raphael Bastianon ¹ , Esteban Quiceno ¹ , Jacob Greisman ¹ , Mohamed Soliman ¹ , John Pollina ¹ , Jeffrey Mullin ¹

¹ University at Buffalo Neurosurgery - UBNS, Spine, Buffalo, United States

Introduction: Cervical pedicle screws (CPS) were first introduced by Abumi in 1994.They were used in traumatic cases with good rates of neurological recovery and correction of deformities reported by the authors. The use and indications were extrapolated for other cases a few years late. Since then, multiple studies have been published describing the results of CPS and comparing the anatomic feasibility and biomechanics differences between pedicle and lateral mass techniques. The major drawback is the higher risk of neurovascular structures associated with CPS placement. The anatomy of the sub axial cervical vertebrae can present significant variations and offer limitations during surgical instrumentation. In this systematic review, the authors evaluate the main measures for the sub axial spine pedicles among different populations from distinct continents. Material and Methods: A comprehensive search was conducted using PubMed, Google Scholar, and EMBASE. The authors included anatomical studies with computed tomography (CT) measurements, cohort studies, and case series. Participants included adult populations from diverse countries on different continents. Four key measurements were analyzed in the studies: Pedicle Width (PW), Pedicle Height (PH), Main Maximal Screw Length (MSL), and Pedicle Transverse Angle (PTA). The authors grouped the studies based on geographic location and ethnic characteristics (e.g., the USA and Europe were combined into one group as they predominantly included Caucasian populations). Subgroup 1 (East Asia) consisted of Japan, China, and South Korea. Subgroup 2 (Southern Asia) included India, Pakistan, and Nepal. Countries from the Middle East were categorized under Subgroup 3. The USA and Europe (both including Caucasians) were placed in Subgroup 4. Countries in Southeastern Asia, specifically Thailand, and Singapore composed Subgroup 5. The last Subgroup consisted of studies from Rwanda and Uganda, representing Africa. One study from South America (Brazil) was excluded from the statistical analysis. Results: The cervical spine Computed Tomography (CT) measurements of more than 4153 patients/cadavers from different countries and locations grouped by geographic/ethnicity were obtained. A total of 48 studies using CT measurements were included. A total of 18.702 measurements of PW were analyzed across various studies. Significant differences were observed among the groups for the C3, C5, C6, and C7 vertebrae, with p-values of 0.02, 0.03, 0.01, and 0.02, respectively. The main PW progressively increased from C3 to C7. The PW was largest in Subgroup 1 (Japan, China, and South Korea), followed by the Southeastern Asia Subgroup, and it was significantly smaller in the Southern Asia group. PTA was reported in 40 studies. A total of 16.227 measurements were analyzed from C3 to C7. The test for subgroup differences was significant only for C7. No significant differences were found in PH and MSL among the groups. Conclusion: Understanding the pedicle anatomy and orientation in different populations may enrich the safety of the CPS technique and help select the best candidates for it. Differences in anatomy across various regions should be explored to enhance surgical accuracy and improve procedural outcomes.

ID: 2818

RF227: A retrospective study of all cauda equina referrals received by the on-call spinal unit at Stockport NHS Trust

Opeyemi Oyeleke ¹ , Vik Kapoor ²

¹ Stockport NHS Foundation Trust, Stockport, United Kingdom,

² British Association of Spinal Surgeons, London, United Kingdom

Introduction: Cauda equina syndrome (CES) is a spinal surgical emergency and a delay in confirming diagnosis and commencing treatment can result in permanent lower limb paralysis & bladder/bowel incontinence. This results in high volumes of referrals as there are significant medicolegal costs in failure to identify this. Method: We conducted a retrospective data-gathering exercise was at Stockport NHS Trust which involved the analysis of all suspected CES diagnosis referrals to the Spinal department between August 2023 & August 2024 from the Emergency department. We evaluated these referrals using the Getting It Right First Time (GIRFT) National Suspected Caudal Equina Pathway and qualitative data such as acute onset back and/or leg pain, saddle anaesthesia, bladder and/or bowel incontinence, and magnetic resonance imaging (MRI) scan results were captured. Results: A total of ninety-nine referrals were made during the duration of this audit. Sixty-six percent were females. The highest age demographics for male and females were 0-39 and 50-59, respectively. Following the GIFRT criteria, only eighty-three patients (83%) met the criteria for an emergency MRI scan, while there was only one confirmed case of CES which gives an incidence rate of 1%. Also, only sixty-four patients (65%) got a pre- and post-void bladder scan. Conclusion: There is a need to adhere to the GIRFT suspected cauda equina pathway so only patients who meet the criteria get emergency MRI scans. It would also be beneficial for all suspected cases to get bladder scans done, as this has been shown to be helpful in assessing suspected cases.

ID: 2196

RF228: Surgical treatment for correction of spinal deformities via anterior and posterior approaches: current Brazilian overview and the effects of the COVID-19 pandemic based on Unified Health System (SUS) data

Rodolfo Gomes Dias ¹ , Alysa Almojuela ¹ , Michael Johnson ¹ , Michael Goytan ¹ , Neil Berrington ¹ , Jay Toor ¹ , Sager Hanna ¹ , Mohammad Zarrabian ² , Perry Dhaliwal ¹

¹ Health Science Centre/ University of Manitoba - Winnipeg Spine Program, Department of Neurosurgery, Winnipeg, Canada,

² McMaster Spine Surgery Center, Department of Orthopedics, Hamilton, Canada

Introduction: Spinal deformities like scoliosis involve deviations in the spine's lateral, axial, and sagittal planes, affecting 1-2% of children and adolescents. Idiopathic scoliosis is the most common type. This study aims to present an epidemiological and economic overview of spinal deformity correction surgeries over the past five years within Brazil's Unified Health System (SUS) and assess the impact of the COVID-19 pandemic on these procedures. Materials and Methods: An aggregated observational study was conducted using data from the Department of Information Technology of the Unified Health System (DATASUS). Procedure codes were obtained from the Management System of the Table of Procedures, Medications, Orthoses, and Prostheses (SIGTAP). Ethics Committee approval was not required as the data are publicly available per Resolution No. 510/2016-CNS. The study analyzed the number of procedures, total and average costs, in-hospital stay durations, and mortality rates over a five-year period (2019-2023) across Brazil and its regions. Results were organized in a spreadsheet, and descriptive statistics were employed to understand the national epidemiology of spinal deformity corrections. Approximately 75% of the Brazilian population depends exclusively on the SUS. For statistical analysis, the Chi-Square test was used with significance set at p < 0.05. Results: Over the past five years, 4,307 spinal deformity correction procedures have been performed via anterior and posterior approaches on pediatric, adolescent, and adult patients, accruing a cumulative cost of BRL 48,501,251.45. The average cost per procedure was BRL 11,261.03. Patients had an average hospital stay of eight days and an average mortality rate of 0.86%. The greatest reduction in procedures occurred between 2019 and 2020, decreasing by 32.68% (p < 0.05), likely due to the COVID-19 pandemic. The most significant increase was between 2021 and 2022, rising by 50.96% (p < 0.05), indicating a rebound post-pandemic. Regionally, the Southeast performed the highest number of procedures (1,987), while the North performed the least (60 procedures over five years). The North experienced the largest reduction between 2022 and 2023, decreasing by 57.14%, and the South saw a reduction of 49.11% between 2019 and 2020. Conversely, the North had a 180% increase between 2021 and 2022. These disparities highlight significant differences in healthcare access across Brazil. Conclusion: The COVID-19 pandemic significantly affected corrective spinal surgeries in Brazil, with procedures declining from 893 in 2019 to 616 in 2020. Recovery was observed in 2022 and 2023, with 951 and 1,123 procedures, respectively. The minimal number of procedures in the North during 2022 and 2023 (only 12 procedures) underscores persistent regional disparities. In contrast, the United States performs approximately 38,000 scoliosis surgeries annually for pediatric patients alone, highlighting a substantial disparity in healthcare resources. This emphasizes the need to improve the quality and accessibility of care in Brazil to better serve patients with spinal deformities and enhance health outcomes. Addressing these disparities requires strategic investments in healthcare infrastructure, particularly in underserved regions, and implementing policies that ensure equitable access to essential surgical interventions. Enhancing training programs for healthcare professionals and increasing funding for spinal deformity treatments could contribute to reducing the gap in care availability nationwide.

ID: 2854

RF229: Trends in hospitalizations for intervertebral disc disorders in Brazil: a 2008-2024 analysis of sociodemographic factors and social vulnerability

Vitor Matheus Silva ¹ , Hector Fugihara Kroes ²

¹ Faculdade de Medicina da Universidade de São Paulo (FMUSP), São Paulo, Brazil,

² Faculdade de Medicina da Universidade de São Paulo (FMUSP), São Paulo, Brazil

Introduction: Intervertebral disc disorders significantly affect the quality of life of a considerable portion of the global population, often being associated with chronic pain and functional limitations. Understanding hospitalization patterns is essential for identifying potential risk factors and vulnerabilities associated with these health conditions. This study conducts an epidemiological survey of hospitalizations for these disorders in Brazil using data from DATASUS, a program responsible for disclosing, managing and processing Brazilian public health information, aiming to analyze trends in these hospitalizations over time and correlate them with sociodemographic variables and social vulnerability indicators. Materials and Methods: Data on the number of hospitalizations, sex, race, age group, and year of hospitalization related to cervical disc disorders and other intervertebral disc disorders, covering the period from January 2008 to July 2024, were obtained from the DATASUS database through the Tabnet platform. Vulnerability indices from the IVS-IPEA were correlated by the patient's municipality of residence. Temporal trends were assessed using linear regression models. The predominance of categorical groups was evaluated with the chi-square test. The reported relationships exceeded the adopted significance level of 0.05. All analyses were performed in R v4.3.1, using the RStudio v2023.09.1+494 interface. Results: A total of 186,926 records of hospitalizations for intervertebral disc disorders were identified over the 17 years analyzed. Of these, 101,815 (54.5%) of the patients were male, representing a statistically significant predominance (p < 10^-16) that remained stable throughout the entire time series analyzed. The majority (84.7%) of patients were between 30 and 69 years old, with the peak of the distribution occurring between 40 and 49 years. During this period, trends indicated an increase in hospitalizations among patients over 60 years old and a decrease among those aged 10 to 39 years. Regarding racial distribution, 60.2% of patients were white; 34.8% were mixed race; 3.9% were black; and 1.1% were yellow. However, there was a significant increase in the representation of mixed-race individuals, sustaining an average of 1.7% per year, surpassing the number of white individuals in the last two years of the survey. Additionally, 1.8% of patients resided in areas with very high social vulnerability index (IVS); 24.1% in high; 18.2% in medium; 31.7% in low; and 24.1% in very low. Hospitalizations of residents from areas with very high, high, and medium IVS increased during the period, while those from areas with low and very low IVS decreased. Conclusion: This study indicates significant shifts in the sociodemographic dynamics related to intervertebral disc disorder care in Brazil, reflecting changing patterns in hospitalizations over 17 years. The trends observed suggest an evolving landscape in which access to healthcare may be influenced by factors such as race and social vulnerability. These findings highlight the need for targeted public health interventions to address disparities and improve healthcare access, particularly for populations at greater risk. By understanding these shifts, policymakers can better formulate strategies to enhance health outcomes and ensure equitable care for all individuals affected by these conditions.

ID: 149

RF230: The disaggregated Oswestry Disability Index - What is the most predictive subsection for patient satisfaction after lumbar surgery

Jan Hambrecht ¹ , Paul Koehli ¹ , Roland Duculan ¹ , Erika Chiapparelli ¹ , Ranqing Lan ¹ , Ali Guven ¹ , Gisberto Evangelisti ¹ , Marco Burkhard ¹ , Koki Tsuchiya ¹ , Jennifer Shue ¹ , Andrew Sama ¹ , Frank Cammisa ¹ , Federico Girardi ¹ , Carol Mancuso ¹ , Alexander Hughes ¹

¹ Hospital for Special Surgery, Department of Orthopaedic Surgery, New York City, United States

Introduction: The Oswestry Disability Index (ODI) is crucial in evaluating outcomes of spinal disorders and provides valuable insights into a patient's preoperative status. There is limited information available on the individual characteristics of its subsections and their relation to postoperative patient satisfaction. This study aims to analyze how different ODI subsections and their improvement affect patient satisfaction 2 years after elective lumbar surgery for degenerative lumbar spondylolisthesis (DLS). Material and Methods: Pre- and 2-year postoperative ODI and patient satisfaction were assessed. The analysis included preoperative scores and improvements in each ODI subsection 2 years postoperatively. Satisfaction was rated on a scale of 1 to 5, with scores ≥ 4 deemed satisfactory. Univariate linear regression and ROC analysis established cutoffs for subsection improvement and postoperative target values to achieve postoperative satisfaction. Results: Overall, 265 patients (60% female, 67 ± 8 years) were included. ODI improvement was achieved in 91%, and postoperative patient satisfaction in 73%. Patients with lower postoperative subsection scores and greater differences between pre- and postoperative scores were more likely to be satisfied (all p < 0.001). A postoperative subsection target score of ≤ 1 was associated with patient satisfaction. Change in degree of pain was the most predictive subsection for satisfaction, with an AUC of 0.84 (sensitivity 79%, specificity 86%). Walking (AUC 0.83, sensitivity 87%, specificity 65%), pain intensity (AUC 0.82, sensitivity 79%, specificity 79%), personal care (AUC 0.82, sensitivity 83%, specificity 68%), and standing (AUC 0.82, sensitivity 83%, specificity 83%) all had an AUC greater than 0.80. The postoperative subsection with the lowest predictability was sleeping (AUC 0.69). Conclusion: Pain domains, walking, standing, and personal care were the subsections with the highest predictability for patient satisfaction. These findings on the correlation between different ODI subscales and patient satisfaction are valuable for improving preoperative education, addressing disability, and ensuring postoperative satisfaction.

ID: 2653

RF231: What is the current status of anterior cervical discectomy and fusion (ACDF) surgeries in Brazil? Data from the Unified Health System and the effects of the COVID 19 pandemic

Rodolfo Gomes Dias ¹ , Alysa Almojuela ¹ , Jay Toor ¹ , Michael Johnson ¹ , Michael Goytan ¹ , Neil Berrington ¹ , Sager Hanna ¹ , Mohammad Zarrabian ² , Perry Dhaliwal ¹

¹ Health Science Centre/ University of Manitoba, Winnipeg Spine Program, Winnipeg, Canada,

² McMaster Spine Surgery Center, Hamilton, Canada

Introduction: Anterior Cervical Discectomy and Fusion (ACDF) is a standard surgical procedure for treating cervical spine disorders such as herniated discs and degenerative disc disease when conservative treatments fail. In the United States, ACDF is among the most frequently performed spinal surgeries, with estimates exceeding 130,000 procedures annually. The COVID-19 pandemic disrupted healthcare services globally, potentially impacting the frequency of elective surgeries like ACDF. This study aims to analyze trends in ACDF surgeries within Brazil's Unified Health System (Sistema Único de Saúde - SUS) over a five-year period (2019-2023), focusing on the pandemic's effects and comparing procedure rates with those in the United States to highlight disparities. Material and Methods: An observational study was conducted using publicly accessible data from the Hospital Information System (SIH/SUS) via the Department of Informatics of the Unified Health System (DATASUS). Procedure codes specific to ACDF were extracted from the Management System of the SUS Table of Procedures (SIGTAP). The analysis included the number of approved hospital admissions, average cost per hospitalization, average length of hospital stay, and mortality rate from 2019 to 2023. Data were organized using electronic spreadsheets, and descriptive statistics were applied. A Chi-square test assessed the significance of changes over the years, with a p-value less than 0.05 considered statistically significant. Results: Over the five-year period, a total of 1,379 ACDF procedures were performed within Brazil's public health system. In 2019, there were 281 procedures with an average cost per hospitalization of BRL 3,192.60, an average hospital stay of 11.2 days, and a mortality rate of 3.20%. In 2020, the number of procedures significantly decreased by 21.7% to 220 (p < 0.05), likely due to the pandemic's impact. The average cost slightly decreased to BRL 3,033.50, the average length of stay reduced to 10.1 days, and the mortality rate increased to 3.64%. In 2021, procedures increased slightly to 235, a 6.8% rise from 2020. By 2023, a significant increase to 399 procedures was observed, marking a 63.5% rise from the previous year (p < 0.05). Throughout the period, fluctuations in costs, length of stay, and mortality rates were noted. Conclusion: The study reveals significant trends in ACDF surgeries within Brazil's public health system over five years, highlighting the substantial impact of the COVID-19 pandemic. The decrease in procedures in 2020 reflects the postponement of elective surgeries and resource reallocation to manage the pandemic. The subsequent recovery indicates a resilient healthcare system addressing surgical backlogs. Comparatively, Brazil's average annual ACDF procedures (approximately 276) are markedly lower than in the United States, where over 130,000 ACDF surgeries are performed annually. This stark disparity underscores differences in access to specialized spinal surgeries, healthcare infrastructure, and resource allocation between the two countries. Enhancing access to ACDF in Brazil could improve patient outcomes and align healthcare services more closely with global standards. Understanding these trends is crucial for healthcare policymakers and practitioners to optimize patient care, allocate resources effectively, and enhance the sustainability of surgical services during ongoing and future public health challenges.

ID: 1870

RF232: Critical role of MRI in the diagnosis and management of osteoporotic vertebral fractures in the acute setting

Victor Martin-Gorgojo ^1,2 , Antonio Silvestre Muñoz ^2,3,4 , Sonia Muñoz Donat ⁴ , Sara Burguet Girona ⁵ , Miguel Tena Roig ⁴ , José Miguel Molina Márquez ⁴ , Antonio Martín-Benlloch ^3,6

¹ NSW Spine Specialists, Sydney, Australia,

² Biomedical Research Institute INCLIVA, Clinic University Hospital, Valencia, Spain,

³ Universitat de Valencia, Department of Surgery (Orthopedics), Valencia, Spain,

⁴ Clinic University Hospital of Valencia, Orthopedic Surgery and Traumatology Department, Valencia, Spain,

⁵ IMED Colón Hospital, Valencia, Spain,

⁶ Dr. Peset University Hospital, Orthopedic Surgery and Traumatology Department, Valencia, Spain

Introduction: Osteoporotic vertebral fractures (OVFs) represent a growing clinical challenge due to their increasing prevalence, particularly in aging populations. Despite the clinical importance of OVFs, there is no universally accepted protocol for their diagnosis and treatment. The use of simple radiographs is common, with treatment often initiated based on compatible symptoms. However, this approach may overlook critical aspects of the fracture, leading some to advocate for the routine use of magnetic resonance imaging (MRI). MRI provides superior sensitivity in detecting both acute and chronic fractures, as well as identifying associated soft tissue injuries, such as damage to the posterior ligamentous complex (PLC) and signs of myelopathy. This study seeks to elucidate the role of MRI in managing OVFs during the acute clinical phase and assess its impact on treatment decisions. Material and Methods: Retrospective descriptive study conducted on patients admitted to a tertiary care hospital with suspected acute OVF over a one-year period. Inclusion criteria required patients to have undergone a thoracolumbar MRI within 30 days of symptom onset. The collected data included the presence of acute and/or chronic OVFs, confirmation of the initially suspected fractures through X-ray or computed tomography (CT), involvement of the PLC, detection of myelopathy, and identification of other significant concomitant spinal pathologies. The aim was to evaluate the contribution of MRI in refining the diagnostic process and influencing therapeutic management during the acute phase of OVF. Results: A total of 205 patients (mean age 76.3 years, 160 women [78.0%], 45 men [22.0%]) met the study’s inclusion criteria. Across these patients, 460 OVFs were identified, with 279 (60.7%) being in the acute phase. MRI revealed additional fractures not initially detected by other imaging modalities in 77 patients (37.6%), 47 (61.0%) of whom had at least one acute OVF. Conversely, in 13 patients (6.3%), the fracture that prompted their hospital admission was not confirmed by MRI, and in 6 of these patients (2.9%), no acute fractures were found at other vertebral levels. Furthermore, MRI detected lesions in the PLC in 13 patients (6.3%) and signs of myelopathy in 1 patient (0.5%). Importantly, MRI led to the incidental diagnosis of 2 metastatic lesions (1.0%) and 2 cases of early-stage spondylodiscitis (1.0%), conditions that would have otherwise been missed without the comprehensive assessment provided by MRI. MRI was critical in determining the optimal therapeutic strategy in 23 patients (11.2%). Conclusion: The results highlight the utility of MRI in the diagnosis and management of OVFs during the acute clinical phase, supporting its routine use.

RF14: RAPID FIRE PRESENTATIONS IN SPANISH

ID: 1951

RF233: Effect of treatment adherence on brace effectiveness for adolescent idiopathic scoliosis at 12 months of treatment: a randomized clinical trial

Alejandro Peiró García ¹ , Victor Martin-Gorgojo ² , Imma Vilalta Vidal ¹ , Rocio García Gracía ¹ , Carles Fabrés Martín ¹

¹ Hospital Sant Joan de Déu, Esplugues de Llobregat, Spain,

² NSW Spine Specialists, Norwest Central, Australia

Objective: Conservative treatment of adolescent idiopathic scoliosis (AIS) with full-time (FT) braces has been shown to reduce progression and the need for surgery. Night-time (NT) braces allow for fewer hours of wear, with their effectiveness being controversial. Adherence to treatment with each type of brace is a key factor for success. This study aims to compare therapeutic adherence, in terms of the number of hours worn, between NT and FT braces. Materials and Methods: A randomized clinical trial (PI20/00962) compared FT and NT braces in AIS. The number of hours of use was analyzed by reading thermal sensors installed in the braces during follow-up visits at 3, 6, 9, and 12 months. Radiographic data of the main curve were analyzed at baseline, 3 months, 6 months, and 12 months using Keops software. Results: A total of 78 patients with AIS were recruited, with 35 (44.87%) receiving FT treatment and 43 (55.13%) receiving NT treatment. The initial mean main curve was 35.59º for FT and 34.40º for NT (p = 0.232). At 12 months, NT (N:44) was used for an average of 7.18 hours, while FT (N:35) was used for an average of 10.28 hours. Using 8 hours as the success threshold for NT, 59% adhered to the treatment, whereas 18 hours as the success threshold for FT was met by 16.7%, with the result being statistically significant (p < 0.005). A decrease in the percentage of hours of brace use over time was observed in both groups. In cases that did not meet the required hours, there was an 85.4% success rate (no surgery at the end of treatment), whereas those who met the required hours had a 92.9% success rate. Conclusions: At 12 months of treatment, adherence to NT braces is higher than to FT braces, likely due to associated psychosocial factors. For both NT and FT braces, the number of hours worn decreases over time. Cases that did not meet the hourly goals had a lower success rate of treatment.

ID: 2708

RF234: Impact of reduced cervical muscle mass on degenerative pathology and cervical sagittal imbalance

Sofia Beltrame ¹ , Gonzalo Kido ¹ , Veronica Monzón ¹ , Gaston Camino-Willhuber ¹ , Marcelo Gruenberg ¹

¹ Hospital Italiano de Buenos Aires, Buenos Aires, Argentina

Introduction: Sarcopenia is currently diagnosed based on a decrease in normalized lumbar skeletal muscle mass (SMM), which reflects total body´s SMM. Research also shows that reduced lumbar SMM correlates with increased axial pain, degenerative pathology, and lumbosacral imbalance, and acts as an independent predictor of frailty. However, the role of cervical SMM as a predictor of cervical pathology is still under investigation. This study aims to evaluate the association between sarcopenia and cervical myosteatosis with degenerative pathology and cervical sagittal imbalance. Materials and Methods: We conducted a retrospective analysis of 100 patients who underwent surgery for degenerative cervical spine pathology. All patients had magnetic resonance imaging (MRI) and standing cervical X-rays. Total SMM was calculated using the Swartz et al. formula, measuring the cross-sectional area of skeletal muscle on an axial MRI slice at C3 level. Paraspinal myosteatosis was assessed using the Goutallier et al. classification. We evaluated the correlation of SMM with cervical sagittal balance parameters (C0–C2 lordosis, C2–C7 lordosis, T1 slope, cervical mismatch, thoracic inlet angle, and cervical sagittal vertebral axis) and the presence of degenerative disorders (number of affected discs, spinal canal stenosis, myelomalacia, facet arthrosis, Modic changes, and spondylolisthesis). A multiple linear regression model was employed to assess the association of SMM with predictive variables, with p < 0.05 considered statistically significant. Results: We analyzed 100 patients: 28 were non-sarcopenic (28%) and 72 were sarcopenic (72%). The mean age for the non-sarcopenic group was 44.4 years (SD = 13.7), while the sarcopenic group averaged 60.6 years (SD = 15.9). Significant differences in SMM were noted, with medians of 47.3 (Q1 = 44.1, Q3 = 53.8) in the first group and 38.7 (Q1 = 32.6, Q3 = 47.8) in sarcopenic patients. Among the sarcopenic patients, 88.9% had facet arthrosis, 90.3% had cervical spinal canal stenosis, and 61.1% had myelomalacia. A significant association was found between sarcopenia and myosteatosis (p = 0.0083), particularly for grades 3 and 4 (p = 0.0365; p = 0.0109 respectively), as well as with facet arthrosis (p < 0.001), cervical stenosis (p = 0.0026), and myelomalacia (p < 0.001). A negative correlation between the number of affected discs and SMM was significant (ρ = -0.332, p < 0.001), indicating that lower SMM correlated with more degenerated cervical discs. Significant involvement at C3-C4 (p = 0.0319) and C6-C7 (p = 0.0117) levels was observed in patients with decreased SMM. No significant associations were found between sarcopenia and sagittal balance alignment parameters. However, 7 sarcopenic patients (11%) had T1 slope values > 40°, compared to none in the non-sarcopenic group (p = 0.1641). Conclusion: Decreased MMI at the cervical level was associated with more affected discs, facet arthrosis, spinal canal stenosis, myelomalacia, and severe myosteatosis. Our findings can represent a significant step toward understanding the association between cervical muscle and cervical degenerative disorders. Further studies are needed, but strengthening cervical paraspinal muscles may be crucial for maintaining subaxial cervical spine health.

Keywords: cervical skeletal muscle mass, sarcopenia, paraspinal myosteatosis, degenerative cervical pathology, cervical sagittal alignment.

ID: 789

RF235: Postsurgical behavior of the non-instrumented lumbar curve in idiopathic scoliosis Lenke 1A

Andrey Martinez Pardo ¹ , Mauro Bruzzone ¹ , Abel Benedetto ² , Pablo Rizzi ¹

¹ Hospital Español de Buenos Aires, Orthopaedics, Buenos Aires, Argentina,

² HZGA Manuel Belgrano, Orthopaedics, San Andrés, Provincia de Buenos Aires, Argentina

Introduction: The benefit of selective thoracic fusion in Lenke 1A curves is to obtain correction and arthrodesis of the thoracic curve with a spontaneous correction of the lumbar curve, leaving the latter unfused. The objective of this work was to compare pre-surgical measurements of Lenke 1A curves in a neutral position and in the bending x-rays focusing in the non-structural curve, with the spontaneous correction obtained in the post-surgery. Materials and Methods: In this radiographic retrospective study, 46 patients operated on for Lenke 1 scoliosis between 2015 and 2022 were analyzed. The inclusion criteria were Lenke type 1A adolescent idiopathic scoliosis, undergoing instrumented arthrodesis of the thoracolumbar spine with transpedicular screws selectively, in which pre- and post-operative x-rays were available. The main thoracic curves and the compensatory curve were measured with the Cobb method, as well as the bending x-rays, and the main and compensatory thoracic curves in the postoperative period. The t test was used to compare continuous variables. Correlation analyzes were performed using Pearson correlation coefficients. A p value less than 0.05 was established as statistically significant. For nominal variables, the Chi-square test was used. A p value less than 0.05 was established as statistically significant. Results: The correlation between the percentage of correction of the main curve and the compensatory lumbar curve was statistically significant (r = 0.361 p < 0.05). There was no correlation between the number of fused levels and the correction of the non-structural curve (r: 0.35, p = 0.35). We found no correlation between the Cobb degrees of the postoperative main curve degrees and the preoperative inclination towards convexity, nor in the non-structural curve (r = 0.037, p = 0.84; r = 0.249, p = 0.17). The inclination of the L4 vertebra in the preoperative vs. postoperative showed no statistically significant differences (Fischer's Chi square 17.911, df: 4, p = 0.01). Concerning to the inclination of L4, 21 cases (67.7%) tilted towards the convexity of the compensatory curve, and 10 (32.3%), towards the concavity. Conclusion: The curve correction rate in our series was high in all cases. There was no correlation between the correction of the compensatory curve in the bending x-rays and same curve in the postoperative, which suggests that there are other factors that include the spontaneous correction of the latter. There was a positive correlation between the correction of the main curve and the compensating one. L4 inclination did not show significant changes between pre- and postoperative.

ID: 2360

RF236: Drenacol: wound drainage in lumbar fusion for degenerative disease. a multicenter and randomized study

Marcelo Molina ^1,2 , Ramón Torres ¹ , Lucio Gonzales ¹ , Karen Weissmann ³ , Marcos Ganga ⁴ , Roberto Postigo ⁵

¹ Instituto Traumatológico, Traumatología y Ortopedia, Santiago, Chile,

² Universidad de Chile, Santiago, Chile,

³ Clinica MEDS, Ortopedia y Traumatología, Santiago, Chile,

⁴ Clínica Santa María, Ortopedia y Traumatología, Santiago, Chile,

⁵ Clínica Universidad de los Andes, Ortopedia y Traumatología, Santiago, Chile

Introduction: Drains for surgical wound management are frequently used in spine surgery. They are often used to decrease the incidence of postoperative hematoma and decrease wound tension. No conclusive evidence in the literature supports using drains to avoid complications in degenerative lumbar spine surgery. We aimed to evaluate wound drains in patients with lumbar arthrodesis for degenerative disorders based on clinical outcomes, complications, hematocrit, and length of stay. Material and Methods: The study design is a multicenter randomized prospective controlled clinical trial. We enrolled surgical candidates for posterior lumbar decompression and fusion surgery for degenerative disorders from October 2019 to August 2021. Patients were randomized into the drain or nondrain group at nine hospitals. The inclusion criteria were as follows: patients aged 40 to 80 years with lumbar and radicular pain, lumbar degenerative disorder, and primary surgery up to three levels. The exclusion criteria were bleeding abnormalities, bleeding > 2,500 mL and dural tears. Preoperative data including Oswestry disability index (ODI), SF-36, lumbar and lower extremity visual analog scale (VAS), body mass index (BMI), hematocrit, and temperature were recorded. Surgical parameters, including surgical time, complications, estimated blood loss (EBL), postoperative temperature and hematocrit (days 1 and 4), dressing saturation, and length of hospital stay (LOS), were registered. The two groups were assessed preoperatively, perioperatively and at the 1-month follow- up. A REDCap database was used for registration. Data analysis was performed using classical statistics. Results: One hundred one patients were enrolled using the Redcap database, and 93 patients were evaluated at the final follow-up. Forty-five patients were randomized to the drain group, and 48 were randomized to the nondrain group. The preoperative characteristics were equivalent in both groups: demographic aspects, pain, ODI, SF-36, BMI, hematocrit, and spine pathology. Surgical time, EBL and complications were similar, with no difference between the groups. No difference was found between BMI and complications. No difference was observed in dressing saturation or postoperative temperature between the groups. The postoperative day 4 hematocrit was higher in the nondrain group [36.4% (32-39)] than in the drain group [34% (29.7-37.6)] without statistically differences (p = .054). The LOS was higher in the drain group [4 (3-5) days] than in the nondrain group [3 (2-4) days] (p = .007). The quality-of-life score, SF-36, was higher in the nondrain group [67.9 (53.6-79.2)] than in the drain group [56.7 (49.1-66)] (p = .043). Conclusions: Nondrain patients presented shorter LOS and better outcomes, with similar complication rates. No difference was found between BMI and complications. Based on this study, in patients undergoing primary posterior spinal decompression and fusion up to three levels for degenerative lumbar disorders, we do not recommend the use of postoperative drains.

ID: 1076

RF237: Recosan: Santiago Spine Surgery Registry, a prospective and multicenter study of 2204 patients

Marcelo Molina ^1,2 , Lucio gonzales ² , Karen Weissmann ³ , Ratko Yurac ⁴ , Ramón Torres ² , Daniel Lobos ⁵ , Juan pablo Otto ⁶

¹ Clínica Alemana, Ortopedia y Traumatología, Santiago, Chile, ² Instituto Traumatológico, Ortopedia y Traumatología, Santiago, Chile, ³ Clínica MEDS, Ortopedia y Traumatología, Santiago, Chile, ⁴ Clínica Alemana, Ortopedia y traumatología, Santiago, Chile, ⁵ Hospital Sótero del Rio, Ortopedia y Traumatología, Santiago, Chile, ⁶ Hospital DIPRECA, Ortopedia y Traumatología, Santiago, Chile

Introduction: The Santiago Spine Surgery Registry (RECOSAN) is the initial prospective and multicenter study of spine pathology in Chile. The preliminary analysis, published in 2021, included 832 patients. The aim was to analyze the epidemiological characteristics, diagnoses, surgical techniques, and complications of spinal pathologies treated in hospitals in Santiago. Methods: This was a descriptive, prospective, and multicenter study conducted at 10 healthcare centers in Chile from September 2020 to June 2024. The study included patient history, type of pathology, diagnosis, surgical technique, complications, days of hospitalization, and 1-month follow-up. The data was compared to RECOSAN 2021. The study was approved by Ethics Committees and the statistics were analyzed using SPSS v26.0. Results: The study included 2204 surgeries, with 50.9% female patients and an average age of 50 years. 70% of the surgeries were performed in private centers, 6% in military hospitals, and 24% in public hospitals. Degenerative pathologies accounted for 72% of the surgeries, trauma for 9%, and deformities for 8%. The most common diagnoses were lumbar herniated disc and lumbar stenosis, accounting for 34% and 15% respectively. 48% of the surgeries were arthrodeses, and 20% of the patients had undergone previous surgeries. The study also included data on surgical time, bleeding, and complications by type of pathology. Intraoperative complications were observed in 3% of cases. The average length of stay duration was 4 days, with the longest being 22 days for spondylodiscitis. Post-operative complications within a month of surgery occurred in 14% of cases. Significant associations were observed between intraoperative complications and bleeding (p < 0.001), as well as between complications and the duration of length of stay (p < 0.001). No significant differences were found compared to RECOSAN 2021. Conclusion: The study provided an epidemiological evaluation and analyzed surgical parameters, days of hospitalization, and complications by pathology and type of surgery, with results consistent with RECOSAN 2021. This study represents the first registry of spinal surgeries on a national level, featuring the largest case series with standardized information on diagnosis, surgical technique, and complications.

ID: 1211

RF238: Endoscopic treatment of recurrent lumbar disc herniation: experience after 42 cases and review of the literature

Alexis Montes Martinez ¹

¹ Hochtaunus Klinik, Neurosurgery, Bad Homburg, Germany

Introduction: Recurrence of lumbar disc herniation is a prevalent challenge within neurosurgery and orthopedic practice. Surgical intervention carries inherent risks, particularly due to scar tissue from prior operations, which can complicate reoperations. This study presents our experience with 42 cases of recurrent lumbar disc herniation managed through endoscopic techniques and compares our findings with existing literature. Materials and Methods: This retrospective study was conducted at the “Hochtaunus” clinic in Bad Homburg, Germany, under the practice of a single surgeon. The postoperative follow-up period for patients ranged from 4 to 12 months. A systematic review was also performed using the PubMed database, focusing on publications regarding “recurrence of lumbar disc herniation” and “complications of spinal endoscopic surgery.” Results: A total of 42 patients were included in the study, comprising 33 males and 9 females. Among the cohort, 37 patients experienced recurrent lumbar disc herniation following initial conventional microscopic surgeries, while 5 recurrences were noted after previously conducted endoscopic procedures, and 2 were identified as second recurrences. Notably, seven instances of spinal dura mater rupture were documented during surgery; however, there were no cases of cerebrospinal fluid leakage, infections, or nerve injuries reported in the postoperative period. Conclusion: The findings indicate that uniportal endoscopic surgery is an effective and safe technique for treating recurrent lumbar disc herniation. Although the procedure presents unique technical challenges attributed to scar tissue, successful dural repair was achieved with no significant postoperative complications. Future studies are essential to directly compare the complication rates of endoscopic surgery with those of conventional surgical methods for this condition, further guiding clinical decision-making.

Keywords: Endoscopic surgery, lumbar disc herniation, recurrence, complications, systematic review.

ID: 2547

RF239: Proposal algorithm for diagnostic and treatment of thoracic and lumbar spondylodiscitis in Mexico

Gabriela Moscoso Saquicela ¹ , Marco Marban Heredia ¹ , Juvenal Ordaz Vega ¹ , Luis Miguel Munguia Leon ¹ , Luis Villegas Esquivel ¹ , Alfredo Sandoval ¹ , Miguel Sanchez Aquino ¹ , Hugo Vilchis Samano ¹

¹ Instituto Mexicano del Seguro Social, Hospital de Traumatologia y Ortopedia Lomas Verdes, Cirugia de Columna , Naucalpan, Mexico

Introduction: The POLA classification of pyogenic spondylitis is based on radiological and clinical features to define a diagnostic and treatment algorithm. Material and Methods: Retrospective, longitudinal and observational study. 73 patients of both sexes diagnosed with spondylodiscitis participated. To determine the relationship of POLA classification with treatment and diagnosis, the Chi-square test was used. Results: A total of 73 patients were included (25 women and 48 men), the average age was 56 years, the most affected level was the lumbar (50 patients), the main type was primary (56 patients), in most the causal agent was detected, E. coli predominated (19 patients), all had neurological involvement, of a motor type (49 patients), pain was also a constant, severe (41 patients), the relationship between surgical or conservative treatment in group A, stable, and group B, unstable, has statistical significance (p = 0.01). Conclusion: The POLA scale classification is helpful in determining the diagnosis and treatment in patients with thoracic and lumbar discitis. Type A2 was the most frequent with 27.4% and without instability 84.9%. The POLA scale is related to the treatment, whether surgical or conservative, and allows for the proposal of a diagnostic and therapeutic algorithm.

ID: 2565

RF240: Access to technology and education for the development of minimally invasive spine surgery techniques in Latin America

Matias Orellana ¹ , Alfredo Guiroy ¹ , Martin Gagliardi ² , Juan P. Cabrera Cousiño ³ , Nicolas Coombes ⁴ , André de Oliveira Arruda ⁵ , Néstor Taboada ⁶ , Asdrubal Falavigna ⁷

¹ Clínica de Cuyo, Cirugia de Columna, Mendoza, Argentina,

² Hospital Español, Mendoza, Argentina,

³ Hospital Clinico Regional de Concepcion, Concepcion, Chile,

⁴ Axial Medical Group, Buenos Aires, Argentina,

⁵ Instituto Columna, Belo Horizonte, Brazil,

⁶ Clinica Portoazul, Barranquilla, Colombia,

⁷ Universidad de Caxias do Sul, Caxias do Sul, Brazil

Introduction: to evaluate the access to technologies and education to perform minimally invasive spine surgeries in Latin America. Material and Methods: we designed a questionnaire to evaluate characteristics of surgeons, their access to different technologies and their possibilities of education in minimally invasive spine surgery techniques. The survey was sent to members and registered users of AO Spine Latin America from 6th-20th January 2020. Major variables studied were nationality, specialty (orthopedics or neurosurgery), level of complexity of the hospital, number of surgeries performed per year by the spine surgeon, types of spinal pathologies commonly managed, number of minimally invasive spine surgeries performed per year. Other variables were related to specific access to different technologies: fluoroscopy during the procedures, access to percutaneous screws, cages, tubular retractors, microscopy, intraoperative CT, navigation and BMP. Finally, we asked about the main limitations and access to education in these techniques in the region. Results: the questionnaires were answered by 305 members of AO Spine Latin America from 20 different countries. Most responses were obtained from orthopedic surgeons (57.8%), those with more than 10 years of experience (42.4%). Majority of surgeons worked at private practice (46.4%), performed more than 50 surgeries per year (44.1%), but only 13.7% performed more than 50 minimally invasive spine surgeries per year; and there are mainly degenerative pathologies (87.5%). Most surgeons had always access to fluoroscopy (79%). Only 26% always has access to percutaneous screws, 24% to tubular retractors, 34.3% to cages (ALIF, LLIF or TLIF) and just 43% always had access to microscopy. About technologies, 71% never had access to navigation, 83% never had intraoperative CT and 69.3% never had BMP. The main limitations to widely used MISS technologies found were high cost of implants (69.3%) and high cost of navigation (49.3%). Most surgeons had access to online education activities (71%), but only 44.9% had access to face to face events and 28.8% to hands on activities; mainly because the courses were expensive (62.7%) or there are few courses in the region related with this topic (51.3%). Conclusion: most surgeons in Latin America had limited resources to perform minimally invasive spine surgery even in private practice. The main barrier mentioned was the costs of implants, technologies and face to face education opportunities.

ID: 2498

RF241: Neuromuscular scoliosis. Is the bipolar technique an alternative to posterior fusion in pediatric age?

Guillem Paz Ramirez ¹ , Imma Vilalta Vidal ² , Alejandro Peiró García ² , Carles Fabrés Martín ² , Rocio García Gracía ²

¹ Hospital de Mataró, Mataró, Spain,

² Hospital Sant Joan de Deu Barcelona, Barcelona, Spain

Introduction: Neuromuscular scoliosis (NM) in pediatric patients is progressive and does not respond to conservative treatment. Surgical treatment is demanding, with posterior spinal fusion, with or without pelvic inclusion, being the most common approach. Perioperative complications are reported in 24%-75% of cases, depending on the series (infection 32%, mechanical 12.7%, pulmonary 22.7%). Minimally invasive techniques, such as the bipolar approach, are gaining popularity with the goal of reducing complications and blood loss while maintaining adequate correction. Since 2019, our center has used the bipolar technique in NM patients. The objective of this study is to assess whether this technique can be an alternative to posterior fusion by minimizing perioperative complications. Material and Methods: We present a retrospective observational study of 38 NM scoliosis patients who underwent surgery using the bipolar technique (proximal hooks, distal or iliac screws) between 2019 and 2023. Data collected include demographic information, radiological data (pre- and postoperative coronal/sagittal Cobb angle, pelvic obliquity, hip dislocation), pre- and postoperative blood analysis, surgical time, transfusions, complications, and any required treatments. Results: Of the 38 patients (16 girls and 22 boys, ages 10-18, mean age 14.2 years), the average follow-up period was 20 months. Diagnoses included Spinal Muscular Atrophy (SMA, N = 12), Duchenne Syndrome (N = 4), Cerebral Palsy (CP, N = 4), Prader-Willi Syndrome (N = 3), Rett Syndrome (N = 3), and others (N = 12). Ten were ambulatory, and 28 were not. Preoperative halo traction was required in 12 patients (32%), and 32 (84.2%) needed non-invasive ventilation (NIV) adaptation before surgery. The mean preoperative Cobb angle was 96º, reduced to 54° postoperatively. The mean preoperative kyphosis was 65°, reduced to 39° postoperatively. Pelvic obliquity decreased from 18° to 6°. Hip dislocation was present in 23 patients pre-surgery (60%). The mean surgical time was 187 minutes. Preoperative blood analysis showed a mean hematocrit of 41.3 and hemoglobin of 13.6, while postoperative values were hematocrit 28.5 and hemoglobin 9.6. Twelve patients required transfusions (32%) with an average of 1.6 units of blood. The mean hospital stay was 7.8 days for community patients and 11 days for out-of-community patients. Complications occurred in 11 patients (28.95%): 6 infectious (15.7%) (Gram-negative bacilli), 5 superficial wound dehiscence (treated with antibiotics), and 1 deep infection (2.6%) requiring debridement. Mechanical complications occurred in 6 patients (15.7%): 4 proximal anchorage failures (10.5%) (between 15 days and 8 months postoperatively), and 3 rod fractures (7.8%) (1.6 years postoperatively). One patient (2.6%) had pulmonary complications. At follow-up, 80% reported no pain and had a good recovery. Conclusion: We believe the bipolar technique is a viable alternative to posterior fusion, requiring less surgical time, fewer transfusions, and a lower complication rate compared to what is reported in the literature for posterior fusion.

ID: 694

RF242: Comparison of complication rates between anterior versus posterior approaches for treating unstable Hangmans’s fracture. A systematic review and meta-analysis

Matias Pereira Duarte ¹ , Martin Gagliardi ² , Charles Carazzo ³ , Gaston Camino-Willhuber ⁴ , Alberto Gotfryd ⁵ , Alfredo Guiroy ⁶

¹ Clinica La Pequeña Familia, Junin, Argentina,

² University of Calgary, Spine Program, Neurosurgery, Calgary, Canada,

³ Passo Fundo University, Neurosurgery, Rio Grande do Sul, Brazil,

⁴ Policlinica Guipuzkoa, Orthopaedics, San Sebastina, Spain,

⁵ Santa Casa of Sao Paulo Medical School and Hospitals, Orthopaedics, Sao Paulo, Brazil,

⁶ Elite Spine Health and Wellness, Neurosurgery, Florida, United States

Introduction: A Hangman’s fracture, or traumatic spondylolisthesis of the axis, is defined as a bilateral fracture of the pars interarticularis of the C2 vertebra resulting in a traumatic spondylolisthesis of C2 over C3. It is the second most common fracture pattern of the C2 vertebrae following odontoid fractures. When internal fixation is required, the surgeon must decide whether an anterior or posterior approach is necessary. However, previously published reviews have not found any significant difference between approaches. The objective was to compare the complication rates associated with anterior and posterior approaches for the surgical treatment of unstable hangman’s fractures. Material and Methods: A systematic review and meta-analysis were performed following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines in PubMed, Web of Science, and Scopus databases to identify comparative studies reporting complications of anterior versus posterior approaches for the treatment of unstable hangman’s fractures. Results: The search yielded 1163 papers from which 5 studies were fully included. One hundred fifteen (115) patients were operated on using an anterior approach versus 65 through a posterior approach. The average complication rates for the anterior and posterior approaches were 26.1 % and 13.8 %, respectively. No com- plications following the anterior approach required pharmacological or surgical intervention (Clavien-Dindo, Grade 1), while 88.9 % of complications following the posterior approach did (Clavien-Dindo, Grade 2). Conclusion: No significant differences in the complication rates were found when comparing anterior versus posterior surgery for treating a C2 traumatic spondylolisthesis. However, most of the complications presented in the posterior surgery group were more severe.

ID: 849

RF243: Awake and outpatient anterior endoscopic cervical foraminotomy for spondyloarthrosis

Gabriel Alonso Cuéllar ¹ , Nicolás Prada Ramírez ¹ , Jorge Ramirez ¹ , Carolina Ramirez ¹ , José Rugeles ¹

¹ LESS Invasiva Academy, Research & Education, Bogotá, Colombia

Introduction: The global increase in longevity represents the success of public health policies, and Latin America has yet to be immune to this phenomenon. The WHO estimates that Latin Americans will live between 70 and 79 years. Therefore, in recent years, an increase in degenerative diseases that cause disabling pain has been observed; these pathologies include spine lesions like cervical spondylarthritis. This degenerative disease is usually found in patients over 50. Secondary pain is caused by foraminal narrowing caused by herniated discs or osteophytes [3]. Anterior cervical discectomy with fusion (ACED) developed in 1949, continues to be the gold standard for this pathology. However, it has been related to complications such as dysphagia, postsurgical hematoma, unilateral paralysis of the recurrent laryngeal nerve, pseudoarthrosis, and adjacent segment. To minimize the morbidity related to conventional procedures, mainly in elderly patients with inherent diseases and risks, techniques such as anterior endoscopic cervical foraminotomy (AECF) have been developed, offering similar clinical results with apparent advantages. This article aims to report the results obtained with the anterior cervical endoscopic technique for treating lateral stenosis caused by cervical spondyloarthritis. Material and Methods: This is a retrospective study in which the medical history and clinical results of patients who consulted for symptoms of cervical pain radiating to the arms, with radiological images consistent with spondyloarthritis, and who underwent surgery with the AECF technique were evaluated. Three outcome criteria were selected: the visual analog scale of leg pain (VAS), the Vernon & Moir test, and the modified Macnab. VAS and ODI criteria were evaluated in the preoperative and postoperative periods. The modified Macnab criteria was implemented in the immediate postoperative controls and at maximum follow-up time. Results: The AECF technique for treating lateral stenosis due to cervical spondyloarthritis was performed in 18 patients. 67% of the sample were women (12), while 33% were male patients. The average age of the sample was 67.9 (SD 12.45) years, ranging between 44 and 80 years. The modified Macnab criteria had an improvement rate of 97%. Patients reported 90% excellent to good satisfaction with the procedure. 7% of patients indicated regular improvement, and only 3% had poor results. Regarding functionality, the Vernon & Moir test showed results after the 24-month follow-up. They perceived improved neck and arm pain as excellent and good at 66%, improvement at 27%, and worst at 7%. Finally, patients reported a preoperative pain score of 8,0 on the VAS and then, in the postoperative period, a score of 2.83 (p < 0.05). In this sample, no complications or reoperations were associated with the procedure. Conclusion: According to the results obtained in this series, AECF can be considered a viable surgical option. Likewise, the existing evidence allows the endoscopic technique for treating lateral stenosis to be considered an alternative. However, it is essential to increase the level of evidence in the different research studies that involve this technique.

ID: 1154

RF244: Awake and outpatient endoscopic management for lumbar facet synovial cyst

Nicolás Prada Ramírez ¹ , Gabriel Alonso Cuéllar ² , Jorge Ramirez ² , Carolina Ramirez ³ , Viviana Plazas Bedoya ³ , José Rugeles ³

¹ Clínica Foscal Internacional, Bucaramanga, Colombia,

² LESS Invasiva Academy, Bogotá, Colombia,

³ Clínica Reina Sofía, Bogotá, Colombia

Introduction: Facet synovial cysts (FSC) are benign lesions that grow mainly from the synovium of the facet joint. FSC are characterized by a rapid appearance of radicular symptoms that can be initially managed with conventional medical treatment including analgesics and modification of physical activity. In cases where medical and interventional treatment does not offer favorable results, it is necessary to implement invasive techniques such as open decompression or facet excision, which, although are considered the most efficient procedures available, are related to complications, risk of segmental instability (when not complemented with fusion), adjacent segment syndrome and high reoperation rates. Recently, have been published studies that use minimally invasive techniques, including endoscopy This retrospective study aimed to examine the feasibility of implementing the most common endoscopic approaches - interlaminar and transforaminal - for treating FSC. Material and Methods: This is a retrospective study where were reviewed charts of patients who were admitted between April 2017 and August 2023 with radicular symptoms secondary to FSC. The population was divided into two groups: the first, patients treated with transforaminal endoscopy, and the second, those treated with an endoscopic interlaminar approach. Three outcome criteria were selected: visual analog scale of leg pain (VAS) and the Oswestry Functionality Index (ODI) and the modified Macnab. VAS and ODI criteria were evaluated in the preoperative and postoperative period. The modified Macnab criteria was carried out in the immediate postoperative controls and at maximum follow-up time. Results: Ten patients met all inclusion criteria. There were no differences in sex distribution. The average age was 58.9 ± 15.1 years. The average duration of the procedure was 65.3 ± 41.0 minutes. Both groups significantly decreased the clinical parameters evaluated (VAS and ODI). Pre-surgical VAS and the VAS taken at maximum follow-up was an average of 7.40 ±1.50, going from 9.60 ± 0.69 in the preoperative period to 2.20 ± 1.40 (p = 0.005). The average ODI of the patients before surgery was 62.6 ± 16.9 points, moved after surgery to a score of 18.8 points on average, this difference being statistically significant (p = 0.008). There were no differences between clinical outcomes when comparing the two groups (p > 0.05). 80% of patients reported a MacNab between good and excellent. The two patients (women) with fair and poor satisfaction in the Macnab criterion also had differences of less than 3 and 30 points in the VAS and ODI criteria. Both were approached through the interlaminar route. Conclusion: Spinal endoscopy offer new options for treating different degenerative pathologies of the lower back and particularly of the facet joints. Full- endoscopic FSC decompression is a technically feasible procedure. Compared with other results reported in the literature, the results obtained in this study show that those obtained in this sample correspond to what was found in the literature.

ID: 1337

RF245: Traumatic injuries of the cervicothoracic junction: a multicenter retrospective cohort

Guillermo Ricciardi ^1,2,3 , Guisela Quinteros Rivas ⁴ , Ignacio Cirillo ^5,6,7 , Juan P. Cabrera ⁸ , Edgar Márquez García ⁹ , Charles Carazzo ¹⁰ , Ratko Yurac ⁴ , Alfredo Guiroy ¹¹

¹ Centro Médico Fitz Roy, Ortopedia y Traumatología, Ciudad Autónoma de Buenos Aires, Argentina,

² Sanatorio Guemes, Ortopedia y Traumatología, Ciudad Autónoma de Buenos Aires, Argentina,

³ Hospital General de Agudos Dr. T. Álvarez, Ortopedia y Traumatología, Spine surgery, Ciudad Autónoma de Buenos Aires, Argentina,

⁴ Clinica Alemana, Santiago, Chile,

⁵ Hospital del Trabajador, Santiago, Chile,

⁶ Universidad Andrés Bello, Santiago, Chile,

⁷ Clinica universidad de los Andes, Santiago, Chile,

⁸ Hospital Clínico Regional de Concepción, SAntiago, Chile,

⁹ Hospital de Traumatología Dr. Victorio de la Fuente Narvaez - Instituto Mexicano del Seguro Social (Mexico), Mexico, Mexico,

¹⁰ University of Passo Fundo, São Vicente de Paulo Hospital, Passo Fundo, Brazil,

¹¹ Elite Spine Health and Wellness Center, Florida, United States

Introduction: We aim to analyze a multicenter cohort of patients surgically treated for C7-T1 traumatic injuries with focus on its surgically approach and complications. Material and Methods: This is a retrospective multicenter cohort study of patients surgically treated for cervical trauma among Latin American institutions during the period between January 1st 2014 and January 1st 2023. We included adults (> 18 years-old) of any gender who had undergone surgery for C7-T1 fractures. Penetrating trauma, follow-up less than 3 months and incomplete medical records with regard to critical data on the time from trauma to surgery were excluded. We obtained data from medical records according to the following variables: age, gender, injury mechanism, type of hospital (public or private), time to referral from another hospital, comorbidities, associated injuries, neurological status according to ASIA impairment scale (AIS), surgical approach, fixed spinal segments, use of steroids, use of cervical traction, and complications. Results: A multicenter cohort of 545 unstable cervical fractures was analyzed among 13 Latin American spine centers during the study period, resulting in a sample of 55 cases (10%) C7-T1 injuries. Most of them, male patients (n = 41; 73.2%), with an average age of 43.2 years (SD = 14.5). The most common mechanism of injury was a fall from a height (n = 28; 50%), followed by traffic accidents (n = 20; 35.7%). Significant non-vertebral associated injuries were documented in 17 (30.4%) patients. According to fracture type, 47.3% (n = 26) of the patients sustained a Type C C7-T1 injury and 20 patients (n = 35.7%) exhibited dislocated or subluxated (F4) facet joints. Neurological damage was documented in the majority of the sample (n = 35; 63.6%). Cephalic traction was performed in nine patients with type C injuries. The median surgical delay was four days (range 0-110). Posterior approach was undertaken more frequently (n = 25; 44.6%), followed by anterior approach (n = 17; 30.4%) or combined approach (n = 13; 23.2%). Anterior approach was associated with fractures without translation (p = 0.018). We registered 11 complications and 10 patients (17.9%) who experienced at least one early complication. The most frequent was nosocomial pneumonia (n = 3; 25%), while analyzing grouped complications, over half were related to the surgical treatment (n = 7; 58.3%), including surgical site infection (n = 2; 16.7%), cerebrospinal fluid fistula (n = 2; 16.7%), implant failure (n = 2; 16.7%) and postoperative progression of neurological injury (n = 1; 8.3%). It was found that documented complications were statistically significantly related to a larger median length of stay (p = 0.029) and the presence of associated injuries (p = 0.028). Complications were independent of surgical delay (p = 0.256), surgical approach strategy (p = 0.380), length of instrumented segments (p = 0.731), AO type of fracture (p = 0.445), comorbidities or neurological damage (p = 0.322). Conclusion: This multicenter cohort of patients with high-energy traumatic injuries at the cervicothoracic junction has been documented, highlighting the complexity and severity of this entity, which frequently results in neurological damage. The posterior approach was the most common, but the anterior approach was associated with fractures without translation. A high complication rate (17.9%) was observed, with surgical complications being the most prevalent. Complications were associated with a longer median length of stay and the presence of associated injuries.

ID: 812

RF246: Spinal gunshot wounds and infection: myth or truth?

Guillermo Ricciardi ^1,2,3 , Juan P. Cabrera ⁴ , Oscar Martinez ⁵ , Javier Matta ⁶ , Hugo Vilchis Samano ⁷ , Jeasson Perez ⁸ , Charles Carazzo ⁹ , Michael Dittmar ¹⁰ , Ratko Yurac ¹¹

¹ Centro Médico Fitz Roy, Traumatology, Spine Surgery, Buenos Aires, Argentina,

² Sanatorio Guemes, Ortopedia y Traumatología, Cirugía de Columna, Ciudad Autónoma de Buenos Aires, Argentina,

³ Hospital General de Agudos Dr. T. Álvarez, Ortopedia y Traumatología, Cirugía de Columna, Ciudad Autónoma de Buenos Aires, Argentina,

⁴ Hospital Clínico Regional de Concepción, Neurosurgery, Santiago, Chile,

⁵ Hospital Universitario Dr. José E. González, Ortopedia y Traumatología, Monterrey, Mexico,

⁶ Hospital Militar Central, Bogota, Colombia,

⁷ Unidad Médica de Alta Especialidad Hospital de Traumatología y Ortopedia Lomas Verdes IMSS, Naucalpan de Juarez, Mexico,

⁸ Clinica de Columna “Dr Manuel Dufoo Olvera”, Mexico, Mexico,

⁹ University of Passo Fundo, São Vicente de Paulo Hospital, Neurosurgery, Passo Fundo, Brazil,

¹⁰ Centro Médico Puerta de Hierro, Zapopan, Mexico,

¹¹ Clínica Alemana de Santiago, University del Desarrollo, Santiago, Chile

Introduction: We aimed to analyze the development of infectious complications from civilian gunshot wounds to the spine and its association with the type and duration of prophylactic antibiotics administered. Material and Methods: This is a retrospective cohort study of patients treated for spinal gunshot wounds at Latin American institutions between 2014 and 2022. Adult civilian patients aged ≥ 18 years who were treated for spinal gunshot wounds to the spine were included. Patients were excluded if they died prior to the assessment on arrival or were transferred from another center after the first 48 hours of trauma, received antibiotic prophylaxis at another center and/or lacked record of this information, and had gunshot wounds no deeper than the soft tissue or a paravertebral bullet without a bone trajectory. Demographic and clinical data, type of spinal gunshot injury, treatment of penetrating trauma and spinal injury, and infectious complications were recorded. Results: We established a database of 384 patients treated for spinal gunshot wounds among institutions from Mexico (n = 319; 83,1%); Colombia, Venezuela, Brazil, and Argentina. Following the exclusion of patients, 292 patients were included in the analysis. Predominantly adult male civilian patients (n = 251; 86.0%) with a mean age of 32.6 years (SD, 11; range, 18-65) without comorbidities (n = 157; 53.8%) were included. Most injuries were to the thoracic spine (n = 135; 46.2%), followed by the lumbosacral (n = 95; 32.5%) and cervical (n = 62; 21.2%) spine. We documented 20 cases (6.8%) of gunshot wounds to the spine, of which 3 (1.0%) developed spinal infections, 6 (2.1%) developed non-spinal infections (abdominal sepsis in 5 cases and meningitis secondary to brain injury in 1 case), and 11 (3.8%) developed wound infections. Spinal infections included pyogenic discitis in 1 case and meningitis in 2 cases. Most patients (n = 274; 93.8%) received an early course of antibiotic prophylaxis. The median duration of antibiotic therapy was 8 days (0 to 35). Most patients were treated with an extended course of antibiotics. Of these patients, 63 (21.5%) received extended antibiotic therapy due to infectious complications (nosocomial infection or trauma-related infection). Most patients (n = 140; 47.9%) were treated with intravenous broad-spectrum antibiotics, covering gram-positive, gram-negative, and anaerobic bacteria. The median duration of antibiotic prophylaxis was statistically longer in patients with dirty wounds (p < 0.001) caused by high-velocity projectiles (p = 0.001). The incidence of spinal infectious complications was not dependent on the duration of antibiotic administration. A statistically significant difference was observed in the proportion of patients who experienced non-spinal complications, with those who received antibiotics for < 72 hours showing a higher rate of complications than those who received antibiotics for > 72 hours (p = 0.032). Conclusion: Our study indicated a low incidence of spinal infectious complications, with a prevalence of only 1% among all cases. The incidence of spinal infections was not influenced by the duration of antibiotic administration. Conversely, trauma-related non-spinal infections were significantly more prevalent in patients who received a course of antibiotics for less than 72 hours. Further research, in the form of prospective cohort studies and clinical trials, is warranted to address this topic.

ID: 2716

RF247: Can surgical time predict the spectrum of pathogens in surgical site infections in spine surgery?

Sebastián Vial Juillerat ^1,2 , Dennys Gonzales ³ , Andrea Contreras Alfaro ¹

¹ Universidad de Chile, Santiago, Chile,

² Instituto Traumatológico Dr. Teodoro Gebauer, Cirugía de Columna, Santiago, Chile,

³ Instituto Traumatológico Dr. Teodoro Gebauer, Santiago, Chile

Introduction: Surgical site infections (SSI) in spine surgery have an incidence rate between 0.6-17.6%, associated with significant morbidity, costs, and mortality. Multiple risk factors have been described for the occurrence of this complication, including surgical time. In 2023, Algarny and colleagues (DOI: 10.21873/invivo.13255) conducted a study that found an association between the duration of surgery and different pathogens causing SSI. The primary objective of this study is to determine whether there is an association between surgical time and the spectrum of pathogens causing SSI in lumbar spine surgeries. Secondary objectives include evaluating the association of other intraoperative factors, such as durotomy and the use of bone cement, with the type of pathogens identified in these infections. Material and Methods: This is a cross-sectional study that included all patients diagnosed with SSI following spine surgery performed between January 2018 and March 2023 in Instituto Traumatológico Dr. Teodoro Gebauer (Santiago, Chile). Eligible patients were identified through a retrospective review of medical records, and demographic, clinical, and surgical data were collected. Microbiological data were obtained from cultures of wound swabs or tissue samples taken during the treatment of the SSI. Descriptive statistics were used to summarize the demographic and clinical characteristics of the patients. Associations between categorical variables, such as surgical time and the spectrum of pathogens, were evaluated using chi-square tests. Logistic regression analysis was employed to identify independent predictors of the type of pathogen responsible for the infection. Data analysis was conducted using JASP1 and SPSS software. Results: A total of 23 patients with SSI were included in the study. The mean surgical time for these patients was 157 ± 74 minutes, with a range of 40 to 302 minutes. The most frequently isolated microorganism was Staphylococcus aureus, accounting for 10 cases (47.6%), followed by Staphylococcus epidermidis in 3 cases (14.3%) and Pseudomonas aeruginosa in 3 cases (14.3%). The remaining pathogens were isolated in only one case each. There was a statistically significant association between infections caused by S. aureus and shorter surgical times (< 118 minutes) (p = 0.01). In contrast, longer surgeries were more likely to result in infections caused by other pathogens. Furthermore, we found that SSIs caused by S. aureus and S. epidermidis were significantly associated with the occurrence of intraoperative durotomy (p = 0.005) and the use of bone cement (p = 0.001). Conclusion: Our study suggests that there is a correlation between shorter surgical times and the predominance of Staphylococcus aureus as the causative pathogen in SSIs following lumbar spine surgery. Longer surgical durations appear to be associated with a broader spectrum of pathogens. Additionally, intraoperative factors such as durotomy and the use of bone cement were found to be associated with an increased likelihood of infections caused by S. aureus and S. epidermidis. These findings highlight the importance of surgical time management and intraoperative precautions to potentially reduce the risk of specific infections in spinal surgery. Further prospective studies are needed to validate these findings and explore preventive strategies.

ID: 880

RF248: Epidemiology and complications of scoliosis surgery in one country in Latin America

Karen Weissmann ¹ , Marcelo Molina ² , Andres Chain ³ , Rodrigo Varela ² , Juan Otto ³

¹ MEDS/Redsalud, Spine Surgery, Santiago, Chile,

² Clinica Alemana de Santiago/Instituto Traumatologico, Santiago, Chile,

³ MEDS, Spine Surgery, Santiago, Chile

Introduction: Spinal deformities are complex pathologies with a high incidence of complications. Objective: To analyze the epidemiological characteristics, surgical techniques, and complications in spinal deformities operated on in Santiago, Chile. Method: This is an analytical, prospective, and multicenter study of data entered between September 2020 and June 2024 in the “Registro de Columna de la ciudad”, “RECOSAN.” The study included patients diagnosed with adolescent idiopathic scoliosis (AIS), neuromuscular scoliosis (NMS), syndromic scoliosis (SS), congenital scoliosis (CS), early-onset scoliosis (EOS), kyphoscoliosis (K), Scheuermann's disease (SchD), and high-grade spondylolisthesis (SPL). Epidemiological, surgical parameters, and complications were evaluated up to one month postoperatively. Statistical analysis was performed using SPSS. Results: Out of 2204 surgeries, 119 patients had spinal deformities, with 73.12% being female and an average age of 19.4 ± 11.8 years. The breakdown of diagnoses was as follows: 82.4% AIS, 2.5% SS, 5.9% NMS, 0.8% EOS, 2.5% SPL, 2.5% K, and 3.4% SchD. Of the patients, 19.3% had previous comorbidities, and 81.5% were classified as ASA 1. Surgical techniques included 68.9% posterior instrumented arthrodesis, 20.2% vertebral body tethering (VBT), and 2.5% mixed fixation, with an average of 11.52 levels per patient. Osteotomies were performed in 28.6% of cases, with Schwab grades 1 and 2 in 87.9%. The average surgical time was 246.97 minutes ± 135.14, average blood loss was 552.29 ± 421.579 ml, and the average length of hospital stay (LOS) was 4.61 ± 4.23 days. Intraoperative complications occurred in 3.4% of cases, and 7.2% experienced complications within the first month. Significant factors correlating with a higher incidence of intraoperative complications included the type of osteotomy (p = 0.024), surgical time (p = 0.050), blood loss (p < 0.001), ASA classification (p = 0.015), and diagnosis (p < 0.001). Complications also increased LOS (p < 0.001). Conclusion: Spinal deformities accounted for 5.3% of spine surgeries in our city, with 7.2% intraoperative complications and 0.8% permanent neurological damage.

RF15: RAPID FIRE PRESENTATIONS IN PORTUGUESE

ID: 2314

RF249: Retained gunshot projectiles in the spinal column: how do spine surgeons in the Latin America treat them?

Emiliano Vialle ¹ , Otávio Vitório Alvarenga Pereira ¹ , José Orlando Nava ² , Vinícius Lopes Fruet ¹ , Luis Felipe Pereira ³ , João Victor Nascimento Ferreira ³ , Joana Guasque ¹

¹ Pontifícia Universidade Católica do Paraná, Hospital Universitário do Cajuru, Orthopedic and Traumatology Service, Spine Surgery Group, Curitiba, Brazil,

² Unidad de Neurocirurgía y Columna Vertebral, Cuauhtémoc, Mexico,

³ Pontifícia Universidade Católica do Paraná, Curitiba, Brazil

Introduction: Gunshot wounds are the second most common cause of spinal injuries, accounting for 17%-31% of spinal cord trauma and resulting in significant mortality and morbidity in the civilian population. The thoracic spine is the most affected, followed by the cervical and lumbar regions. Despite the severity of these injuries, there is no consensus on the ideal treatment. The aim of this study is to investigate the treatment decisions made by spine surgeons in Latin America regarding gunshot injuries and their complications in the spinal column. Material and Methods: After a systematic review of the topic, 10 key questions were formulated to guide the treatment of gunshot injuries to the spine. A questionnaire was administered to 81 spine surgeons in Latin America with experience in treating gunshot injuries, presenting various possible treatment approaches. The agreement of the responses was evaluated, using a 75% threshold for significant consensus, and the most prevalent responses were compared to the recommendations in the literature. Results: No response achieved greater than 75% agreement with the literature recommendations. There was only agreement among the surgeons that the number of projectiles does not influence therapeutic decision-making, despite a lack of literature support for this conclusion. Conclusion: These results align with our hypothesis prior to the study that there is no standardization in the treatment of gunshot injuries to the spine, and there is a need to encourage the production and updating of scientific knowledge on this topic. Some of the most frequently reported decisions contradict the best evidence in current literature. A critical example of this discrepancy is found in question 2, where most surgeons always remove projectiles from the thoracic spinal canal without proven clinical benefit for the patients, and the risks of this surgery, such as cerebrospinal fluid leaks and infections, outweigh any potential benefits.

ID: 2284

RF250: Management of retained gunshot injuries to the spine - a systematic review

Emiliano Vialle ¹ , José Orlando Nava ² , Otávio Vitório Alvarenga Pereira ¹ , Vinícius Lopes Fruet ¹ , Luis Felipe Pereira ³ , João Victor Nascimento Ferreira ³ , Joana Guasque ¹

¹ Pontifícia Universidade Católica do Paraná, Hospital Universitário Cajuru, Orthopedics and Traumatology Service, Spine Surgery Group, Curitiba, Brazil,

² Unidad de Neurocirurgía y Columna Vertebral, Cuauhtémoc, Mexico,

³ Pontifícia Universidade Católica do Paraná, Curitiba, Brazil

Introduction: Spinal cord injuries from gunshot wounds ranks as the third leading cause of spinal trauma worldwide, representing 17% to 21% of cases. These injuries are particularly prevalent in developing regions, particularly in Latin America and Asia. The impact of these is exacerbated by the significant morbidity, mortality, and socioeconomic burden they impose, especially in low-resource settings. This study aims to review current management strategies and propose guidelines for treating spinal gunshot wounds, considering the complexity of surgical options and varying outcomes. Material and Methods: A systematic literature review following MOOSE, PRISMA, and STROBE guidelines, was conducted focusing on studies from January 1999 to November 2023. We assessed treatment strategies based on projectile location - cervical, thoracic, lumbar, vertebral body, intervertebral disc, facet, and paravertebral muscles - as well as projectile type (lead, copper) and associated complications. Fifty articles were included after stringent selection criteria, leading to the identification of key variables affecting therapeutic decisions. Ten variables that should be considered in decision-making and can influence the therapeutic option were identified: Segment of the spine (cervical, thoracic, lumbar); Location (facet, vertebral body, disc, spinal canal, paravertebral musculature), type of projectile (lead, copper, encapsulated). The selected articles were read critically and evaluated using a checklist of these ten variables. Each article and question were scored individually by two spine surgeons and discrepancies were resolved by senior research. Results: Management of spinal gunshot wounds depends on projectile location and neurological status. In cervical spine injuries, early removal of projectiles is recommended, especially in progressive cases, to potentially enhance neurological recovery. For thoracic spine injuries, projectiles can often be safely retained in non-progressive injuries but should be removed in cases with progressive deficits. In the lumbar spine, removal is recommended for both progressive and non-progressive injuries due to the potential for multiple neuronal compressions. Projectiles in vertebral bodies generally do not require removal unless they affect mechanical stability or surgical access. Projectiles in discs and facets require careful monitoring due to risks of lead poisoning. Lead levels should be checked at the initial time of treatment, two weeks later, and monthly for three months. Projectiles in paravertebral muscles usually do not necessitate removal unless symptoms arise. Copper projectiles often require removal due to the high local inflammatory response they can trigger. When the projectiles are in the path of a possible surgical approach, it should be removed. Conclusion: This review offers evidence-based recommendations to aid clinical decision-making in the management of spinal gunshot wounds. While surgical intervention for spinal gunshot wounds remains controversial, individualized approaches based on projectile location and neurological status can improve outcomes.

ID: 2155

RF251: Psychological follow-up of patients with spinal deformities: a descriptive data analysis in a psychology outpatient clinic

Alexia Sousa ¹ , Rebeca Chaves ¹ , Dielson Sousa ¹ , Bruna Ferreira ¹ , Cibele Maia ¹ , Jose Alberto Oliveira ¹

¹ Hospital Infantil Albert Sabin, Fortaleza, Brazil

Introduction: Spinal deformities can significantly impact the daily lives of children and adolescents. From diagnosis onward, both patients and caregivers report various physical, emotional, and social care needs. Effective treatment requires an integrated approach that addresses these complex needs, as failure to do so may lead to poor physical and mental health outcomes¹. Living with this progressive condition is challenging, often resulting in concerns about appearance, difficulties in social interactions, and dissatisfaction with body image². Psychological support is crucial in managing stress related to diagnosis, treatment, and the progression of the deformity. This study aims to describe the profile of patients with spinal deformities treated in a psychology outpatient clinic, focusing on their psychological demands and the interventions used. Materials and Methods: This cross-sectional descriptive study evaluated the sociodemographic profile, psychological demands, and interventions applied to children and adolescents with spinal deformities in a psychology outpatient clinic at a referral public hospital in Ceará, Brazil, from July 2023 to August 2024. Data were collected from documented psychology service records. Sociodemographic variables (age, gender, origin), psychological demands, and the main therapeutic interventions were analyzed. Statistical analysis was performed using SPSS version 20, with results expressed in absolute and relative frequencies. The study was approved by the Ethics Committee of the Albert Sabin Children's Hospital (CAAE: 81691924.6.0000.5042). Results: The sample included 128 patients, of whom 111 (86.7%) were female, and 117 (91.4%) were between 12 and 18 years old. Most patients came from rural areas (66; 51.5%). Psychological services were also provided to 70 family members, and five operative groups included 20 patients. Patient contact primarily occurred through follow-up appointments (68; 53.1%), interconsultation (40; 31.3%), and active case finding. The main psychological demands were adaptation to illness or treatment (58; 26.7%), emotional responses to surgical procedures or invasive treatments (41; 16.7%), and understanding of diagnosis and prognosis (27; 11%). Interventions included emotional support (75; 26.2%), preparation for invasive procedures (61; 21.3%), guidance/psychoeducation (50; 17.5%), as well as conflict mediation, family bonding support, and psychological documentation. Conclusion: This study underscores the importance of a multidisciplinary approach to caring for adolescents with spinal deformities, highlighting their specific psychological needs. Psychological support was crucial in managing emotional reactions and adapting to treatment, contributing to improved overall care and quality of life. These findings emphasize the need to integrate psychological support as a standard part of treatment for this population.

References

1. Niekerk M, Richey A, Vorhies J, et al. Effectiveness of psychosocial interventions for pediatric patients with scoliosis: a systematic review. World J Pediatr Surg. 2023;6(2).

2. Motyer GS, Kiely PJ, Fitzgerald A. Adolescents' experiences of idiopathic scoliosis in the presurgical period: a qualitative study. J Pediatr Psychol. 2022;47(2):225-35.

ID: 2825

RF252: Outcomes and complications of surgery for neuromuscular scoliosis correction due to myelomeningocele sequelae: a 10-year retrospective study focusing on an exclusively posterior approach

Joao Pedro Oliveira ¹ , Alex Oliveira de Araujo ¹ , Cassio Franco ¹ , Emilson Camapum ² , Vitor Viana Bonan de Aguiar ² , Walter Junior ³ , Ricardo de Amoreira Gepp ² , Cícero Gomes ¹

¹ Sarah Network of Rehabilitation Hospitals, Orthopedic Surgery, Brasília, Brazil, ² Sarah Network of Rehabilitation Hospitals, Neurosurgery, Brasília, Brazil, ³ Hospital Regional do Paranoá, Orthopedic Surgery, Brasília, Brazil

Introduction: Neuromuscular scoliosis associated with myelomeningocele is a complex condition that presents challenges for both surgical and interdisciplinary management. The literature generally indicates that surgical treatment can be performed via both anterior and posterior approaches. The objective of this study is to evaluate the outcomes achieved with the exclusively posterior approach and to compare the hybrid technique using hooks and pedicle screws with the technique that employs only pedicle screws. Material and Methods: All consecutive patients undergoing surgery for the correction of neuromuscular scoliosis due to myelomeningocele between 2012 and 2022 were evaluated retrospectively. Until 2017, patients underwent hybrid construction with screws and hooks. From late 2017 onward, patients were treated with fixation using only pedicle screws. These two groups were compared regarding their outcomes. Results: Fifty patients were included in this series (26 males; 52%), with a mean age of 13.2 ± 2.2 years, a BMI of 18.3 ± 3.5 kg/m², and a mean follow-up time of 51.8 ± 29.7 months (ranging from 12 to 132 months). The mean surgical time was 421 ± 93.3 minutes, and the average blood loss was 891 ± 581.3 mL. The average preoperative Cobb angle was 101.6°, which decreased to 54.7° at the last follow-up (mean difference of -46.9°; p-value < 0.0001). The average preoperative pelvic obliquity was 25.8°, decreasing to 13° postoperatively (mean difference of -12.9; p-value < 0.0001). The main complication was material failure, observed in 15 patients (30%); however, only 2 of these patients required reoperation (4% of the series). Infection occurred in 8 patients (16%), all of whom underwent reoperation. One additional patient was reoperated due to an ischial ulcer. Therefore, the total reoperation rate was 11 out of 50 (22%). Patients who underwent hybrid construction or pedicle screws had similar preoperative Cobb angles (103.7° vs. 99.8°; p-value 0.67). However, the Cobb angle at the last follow-up was lower in the second group, with a statistically significant difference (64.2° vs. 46.1°; p-value 0.0038), indicating a greater correction capacity for this technique. The failure rate of the material was higher in the hybrid construction group, but the difference only approached statistical significance (42% vs. 19% in the pedicle screw group; p-value 0.0837). Demographic parameters, surgical time, intraoperative blood loss, and rates of infection and reoperation were similar between the two groups. Although pelvic obliquity was, on average, greater in the screw fixation group (29.3° vs. 22.1°; p-value 0.0456), the pelvic obliquity at the end of follow-up was statistically similar between the two groups (p-value 0.1899), indicating a greater correction capacity for this parameter with the pedicle screw technique. Conclusion: The study illustrates the technical evolution in the treatment of scoliosis associated with myelomeningocele using an exclusively posterior approach. The data suggest that corrections performed exclusively with pedicle screws are more effective and maintain their results over time. The low failure rate of the synthetic material requiring reoperation encourages the use of the exclusive posterior approach in this population.

ID: 2260

RF253: Profiling biomarkers of oxidative stress and antioxidant response acoording to stages of lumbar disc degeneration

Charles Carazzo ¹ , Alexandre Tognon ² , Manuela Peletti-Figueiró ¹ , Asdrubal Falavigna ¹

¹ Caxias do Sul University, Caxias do Sul, Brazil, ² São Vicente de Paulo Hospital, Research, Passo Fundo, Brazil

Introduction: Degenerative disc disease is one of the primary causes of lower back pain, associated with multiple environmental, occupational, epigenetic, and genetic factors. Initial treatment is conservative, involving medication, injections, and physical therapy. Surgery is indicated only in refractory, symptomatic cases with clinical-radiological agreement. Understanding the pathophysiology of the degenerative process requires comprehension of cellular death and regeneration mechanisms. Oxidative stress has been studied as one of the key molecular factors inducing disc degeneration, attracting researchers' interest due to its association with neurodegenerative diseases and biological factors linked to aging. The objective of this study is to evaluate oxidative stress in the human intervertebral disc in degenerative lumbar disease through protein, genetic, and biochemical markers to aid in understanding the role of oxidative stress in disc degeneration. Material and Methods: Intervertebral disc samples were obtained from 30 patients who underwent surgical treatment for lumbar spine disorders, divided into mild (Pfirrmann grades II and III) and severe (Pfirrmann grades IV and V) groups. The following analyses were performed: I - immunohistochemistry to assess the expression of antioxidant proteins TRX and PRDX/PAG1, II - RT-qPCR to verify the expression of genes NF-κB, GSK3β, and P21/CDKN1A, and III - Biochemical tests to quantify sulfhydryl protein and determine nitric oxide production to assess oxidative stress levels. Results: The TRX protein showed predominant positive expression in chondrocytes and fibroblasts, with significantly higher expression in milder disease grades (75.32 ± 6.65) compared to more severe ones (68.98 ± 8.25) (p ≤ 0.001). PRDX/PAG1 exhibited higher expression in clusters of NP chondrocytes and in milder diseases (65.70 ± 12.15) (p < 0.001). All evaluated genes showed a trend of increased expression in more severe disease grades and presented a positive Pearson statistical correlation, especially the P21/CDKN1A gene, which demonstrated genetic overexpression with significant statistical difference in the most severe grades of pathology (p = 0.038). The sulfhydryl protein was more abundant in milder grades compared to severe grades of pathology (14.42 ± 6.37 vs. 7.52 ± 3.26, p = 0.009). The amount of nitric oxide produced was higher among those with severe degeneration compared to those with moderate degeneration (9.29 ± 2.55 vs. 8.02 ± 0.92, p = 0.290). Conclusion: According to this study, the more severe grades of this pathology (Pfirrmann Scale) occur due to reduced antioxidant activity (TRX, PRDX/PAG1, sulfhydryl proteins), increased expression of inflammatory and senescent genes (NF-κB, GSK3β, P21/CDKN1A), and elevated nitric oxide production, ultimately leading to cellular apoptosis.

ID: 2556

RF254: Evaluation of Google forms usage for applying the Oswestry Disability Index in patients undergoing spine surgery

Mauricio Cardoso ¹ , Andre Castilho ¹ , Pedro Torres ¹ , Rodrigo Cruzeiro ¹

¹ Hospital Unimed, Belo Horizonte, Brazil

Introduction: To evaluate the feasibility and effectiveness of using Google Forms for the longitudinal application of the Oswestry Disability Index (ODI) in patients undergoing spine surgery. Methods: A prospective observational study conducted in a specialized orthopedic clinic in Belo Horizonte, Brazil, between 2021 and 2023. Patients undergoing spine surgery (n = 402) were invited to complete the ODI via Google Forms preoperatively and at 30, 90, 180, and 360 days postoperatively. The clinic secretary made telephone contact and sent the form link via email. Response rates were analyzed over time, by sex, age group, and year of inclusion. Results: Response rates were 100% preoperatively and at 30 days, 93.8% at 90 days, 84.6% at 180 days, and 62.4% at 360 days. Patients between 41-60 years old showed the most consistent high response rates. Women demonstrated slightly higher adherence in longer periods. Patients included in 2021 and 2022 maintained response rates above 98% after one year. Conclusion: The use of Google Forms for longitudinal application of the ODI in spine surgery proved to be feasible and effective, with high response rates, especially in initial follow-up periods. This approach offers a promising alternative to traditional data collection methods, potentially improving the efficiency of postoperative follow-up in spine surgery.

ID: 1631

RF255: Evaluation of vertebral endplate degeneration using modic classification in patients undergoing lumbar descompression surgery for disc herniation: a prospective cohort study

Matheus Castanheira ¹ , Guilherme Pajanoti ² , Felipe Monteiro ¹ , Michel Kanas ² , Delio E. Martins ² , Marcelo Wajchenberg ² , Nelson Astur ²

¹ Instituto Cohen, Sao Paulo, Brazil, ² Hospital Israelita Albert Einstein, Sao Paulo, Brazil

Introduction: Modic changes (MC) are MRI-detected signal alterations in vertebral endplates commonly associated with degenerative disc disease. Types 1 and 2 are most frequently observed in patients undergoing lumbar microdiscectomy, but the effect of surgical intervention on their progression is not fully understood. This study aims to assess the evolution of Modic changes in patients following lumbar microdiscectomy. Material and Methods: A retrospective observational study was conducted, analyzing lumbar spine MRIs from 57 patients who underwent lumbar microdiscectomy. MRI scans were performed preoperatively and 12 months postoperatively. Modic changes (types 1 and 2) were evaluated in terms of prevalence and area size at the surgical level. Statistical analysis was applied to compare the progression of Modic changes between pre- and postoperative MRI scans. Results: Preoperatively, 37% of patients presented with Modic type 1 changes, while 25% had type 2. After 12 months, a significant reduction in the area of Modic type 1 changes was observed, with an average decrease of 59.3%, suggesting a reduction in endplate inflammation. However, no significant reduction in Modic type 2 areas was noted (p = 0.72). Additionally, some patients initially classified with Modic type 1 showed progression to Modic type 2 postoperatively, indicating a possible evolution from Modic type 1 to type 2 after surgery. Conclusion: This study demonstrates that lumbar microdiscectomy significantly reduces Modic type 1 changes, likely reflecting decreased vertebral endplate inflammation. However, Modic type 2 changes appear less responsive to surgical intervention, possibly due to their chronic and structural nature. Understanding these radiological changes can provide better insight into the postoperative management of patients undergoing lumbar microdiscectomy.

ID: 1160

RF256: Long-term pulmonary function after combined anterior-posterior spinal fusion for scoliosis in neurofibromatosis type 1 and Marfan syndrome at mean follow-up of 13 years

Jose Alberto Oliveira ^1,2 , Rogério dos Reis Visconti ¹ , Alderico Girão Campos de Barros ¹ , Plinio Braga Linhares Garcia ¹ , Luis Eduardo Carelli Texeira da Silva ¹ , José Roberto Lapa e Silva ²

¹ Jamil Haddad National Institute of Traumatology and Orthopedics, Rio de Janeiro, Brazil,

² Federal University of Rio de Janeiro, Rio de Janeiro, Brazil

Introduction: This study investigates the long-term (> 10 years) effects of thoracotomy and posterior arthrodesis on pulmonary function in patients with scoliosis secondary to Marfan syndrome versus Neurofibromatosis type 1. Material and Methods: A retrospective cohort study was carried out at the National Health Center reference in spinal surgery to assess the lung function of patients with scoliosis who underwent surgery from 1997 to 2009. A sample of nine patients eligible for the study was obtained after meeting the inclusion and exclusion criteria. The choice of approach was based on radiographic criteria (rigid curves, flexibility < 40%, and/or severe curves > 80°). The procedure was performed in two stages. Interbody spinal fusion was performed during the anterior approach. Eligible patients underwent an assessment during the postoperative period with radiography and spirometry tests. Outcome measures: gender; age (at diagnosis and surgery); corrected height by wingspan; body mass index (BMI); duration of surgery (minutes); estimated blood loss (mL); follow-up (years); pulmonary and implants related complications; preoperative and postoperative Cobb angle of main thoracic curve and of thoracic kyphosis (T5 to T12); number of instrumented levels; absolute and percentage predicted of Forced Vital Capacity (FVC) and Forced Expiratory Volume in 1 second (FEV1). All analyzes were performed in SPSS version 20.0 for Windows, adopting a confidence level of 95%. Results: During the comparison between the groups regarding certain absolute (FVC, FEV1) and predicted percentages (FVC%, FEV1%) parameters of pulmonary function, it was noted that there were no significant differences between preoperative and postoperative values. In the analysis of the Odds Ratio between the etiology of syndromic scoliosis versus pulmonary complications, no greater chance of these was identified between groups. When comparing preoperative and postoperative radiographic values ​​between the groups, a significant reduction (p < 0.05) was observed in the magnitude of the Cobb angle of the main thoracic curve after surgery in patients with Marfan syndrome. However, there was no difference in this variable between the groups, as well as in the preoperative and postoperative thoracic kyphosis values. Conclusion: Considering the %FEV1 and %FVC values, the combined approach did not result in worse pulmonary impairment. The findings suggest that preoperative pulmonary function is a key predictor of postoperative outcomes. This highlights the importance of considering preoperative lung function in surgical planning.

ID: 2436

RF257: Assessing the predictive accuracy of the “dialogue support tool for spine surgery” in a Portuguese patient cohort

Afonso Faria ¹ , Sara Alves ² , Bianca Sousa Barros ¹ , Mário Rui Silva ¹ , Carolina Luísa Lemos ² , Ricardo Rodrigues-Pinto ^2,3

¹ ULS Santo António, Serviço de Ortopedia, Porto, Portugal,

² Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, Porto, Portugal,

³ ULS Santo António, Serviço de Ortopedia, Unidade Vertebro-Medular, Porto, Portugal

Introduction: Despite advancements in surgical techniques and diagnostic tools, some patients undergoing spine surgery may not achieve the desired postoperative outcomes. This dissatisfaction persists even in cases where surgery is technically successful and adherent to appropriate indications, with no guarantee of a satisfactory outcome. Prognostic tools, aiming to align patient expectations pre-surgery, have emerged as potential aids in improving communication between surgeons and patients. This study aims to assess the predictive accuracy of the Dialogue Support (DS) application, based on Swedish Spine Registry, in predicting one-year post-surgical outcomes for a cohort of Portuguese patients undergoing spine surgery. Material and Methods: The study included diagnoses of lumbar disc herniation (LDH), lumbar spinal stenosis (LSS), lumbar degenerative disc disease (DDD), and cervical radiculopathy (CR). Patients with degenerative cervical myelopathy were excluded. A total of 158 patients participated in the survey, providing complete preoperative data and at least a 1-year follow-up. The study captured patients' perspectives on quality of life using the Global Assessment of Pain (GA pain) and satisfaction with surgical outcomes. Data retrieval for the Portuguese cohorts involved manually entering predictions into the DS tool. Variables included operated levels, demographic information, quality of life, comorbidity profile, and pain scores. The degree of concordance at the group level was analyzed using calibration plots, and ROC curves were used to study the predictive capacity at an individual level. Results: On average, the DS tool predicted lower success rates for pain control than what was actually observed in the Portuguese cohorts. Patient satisfaction was generally higher than expected, except for those with cervical radiculopathy (61.5% satisfied vs. 68.3% predicted). In the lumbar disc herniation group, 79.5% were satisfied compared to the 57.8% predicted. For lumbar spinal stenosis, 72.5% reported good outcomes versus 47.5% expected. Finally, 65.0% of patients with degenerative disc disease were satisfied, compared to the 62.9% predicted. The length of stay in the hospital was longer in the study population than expected, except for the cervical group. ROC curves showed low predictive capacity with an AUC (area under the curve) near 0.5, except for the lumbar disc herniation group, where the AUCs were 0.85 for pain control success and 0.81 for reported satisfaction. Conclusion: Many patients with good postoperative outcomes still expressed dissatisfaction, likely due to unmet expectations and lack of preparedness for residual pain. Improving pre-surgical communication and aligning patient expectations are crucial for enhancing satisfaction. The DS can be a useful tool to assist both patients and surgeons in discussing and deciding on surgical treatment for degenerative spine conditions. However, the predictive capabilities of this instrument were not applicable to these Portuguese patient cohorts. Adapting the DS tool to the unique characteristics of the Portuguese population could improve its predictive accuracy and clinical applicability.

ID: 2704

RF258: Direct vertebral rotation versus simple rod derotation tecniques in correction of adolescent idiopathic scoliosis: a systematic review and meta-analysis

Filipi Andreão ¹ , Filipe Ribeiro ² , Davi Coelho ³ , Murilo Mancilha ⁴ , Helvécio Filho ⁵ , André Nishizima ⁶ , Bernardo Nogueira ⁷ , Danilo Gomes Quadros ⁸

¹ Federal University of Rio de Janeiro, Rio de Janeiro, Brazil, Rio de Janeiro, Brazil,

² Barão de Mauá University Center, Faculty of Medicine, Ribeirão Preto, SP, Brazil, Ribeirao Preto, Brazil,

³ CEUMA University, Imperatriz, Brazil, Imperatriz, Brazil,

⁴ Anhembi Morumbi University, São José dos Campos - SP, Brazil, São José dos Campos, Brazil,

⁵ Faculty of Medicine, University of Fortaleza, Fortaleza, Brazil, Fortaleza, Brazil,

⁶ Bahiana School of Medicine and Public Health, Salvador, Brazil, Salvador, Brazil,

⁷ Serra dos Órgãos University Center, Teresópolis, Rio de Janeiro, Brazil, Teresópolis, Brazil,

⁸ Núcleo Oscar Freire, Salvador, BA, Brazil, Salvador, Brazil

Introduction: One method for treating adolescent idiopathic scoliosis (AIS), which is characterized by abnormal spinal align- ment in the coronal, sagittal, and rotational planes, is surgical correction. The two surgical techniques most typically used to correct spine alignment are simple rod derotation (SRD) and direct vertebral derotation (DVR). The objective of the present study is to evaluate the safety and efficacy of Direct vertebral rotation versus simple rod derotation techniques in correction of adolescent idiopathic scoliosis. Methods: We searched Medline, Embase, Web of Science databases following PRISMA guidelines. We used single proportion analysis with 95% confidence intervals under a random-effects model, I² to assess heterogeneity, and Baujat and sensitivity analysis to address high heterogeneity. Eligible studies included those with ≥ 4 patients treated with direct vertebral rotation or simple rod derotation techniques in correction of adolescent idiopathic scoliosis. Results: Ten studies, comprising 615 patients, were analyzed for coronal and sagittal plane outcomes. Sagittal plane analysis found no significant differences between pre and post-operative DVR and SRD for thoracic kyphosis (DVR: MD = 3.61, 95% CI: -0.74 to 7.96, I² = 84%, p = 0.1; SRD: MD = 4.57, 95% CI: -0.44 to 9.59, I² = 86%, p = 0.07) or lumbar lordosis (DVR: MD = -0.07, 95% CI: -3.11 to 2.97, I² = 53%, p = 0.96; SRD: MD = -0.22, 95% CI: -3.68 to 3.24, I² = 55%, p = 0.9). Coronal plane analysis showed significant differences in Cobb angle for thoracic scoliosis (DVR: MD = -39.33, 95% CI: -41.36 to -37.29, I² = 24%, p < 0.01; SRD: MD = -37.56, 95% CI: -40.58 to -34.53, I² = 54%, p < 0.01) and lumbar curves (DVR: MD = -23.96, 95% CI: -27.45 to -20.47, I² = 64%, p < 0.01; SRD: MD = -21.07, 95% CI: -25.15 to -17.00, I² = 64%, p < 0.01), though global coronal balance showed no difference (DVR: MD = -0.02, 95% CI: -2.06 to 2.03, I² = 0%, p = 0.99). Conclusion: This systematic review and meta-analysis indicate that the direct vertebral rotation (DVR) and simple rod derotation techniques for the correction of adolescent idiopathic scoliosis did not show significant differences in the sagittal plane. However, in the coronal plane, the DVR technique demonstrated superior results.

ID: 2722

RF259: A retrospective analysis of open and percutaneous endoscopic surgery for vertebral lumbar disc herniation using propensity score matching

Filipi Andreão ¹ , Filipe Ribeiro ² , André Faria ³ , André Nishizima ⁴ , Helvécio Filho ⁵ , Danilo Gomes Quadros ⁶

¹ Federal University of Rio de Janeiro, Rio de Janeiro, Brazil, Rio de Janeiro, Brazil,

² Barão de Mauá University Center, Faculty of Medicine, Ribeirão Preto, SP, Brazil, Ribeirão Preto, Brazil,

³ Hospital Federal dos Servidores do Estado, Rio de Janeiro, Brazil, Rio de Janeiro, Brazil,

⁴ Bahiana School of Medicine and Public Health, Salvador, Brazil, Salvador, Brazil,

⁵ Faculty of Medicine, University of Fortaleza, Fortaleza, Brazil, Fortaleza, Brazil,

⁶ Núcleo Oscar Freire, Salvador, BA, Brazil, Salvador, Brazil

Introduction: Disc herniation is a relatively common cause of back pain and sciatica. Some surgical techniques are used to treat this pathology, among them open surgery and percutaneous endoscopic surgery. There is still little scientific evidence on the safety and effectiveness of these procedures. This study aims to investigate which technique is safer and more effective, open surgery or percutaneous endoscopic in patients with lumbar disc herniation. Methods: We conducted a retrospective cohort study utilizing the TriNetX database where we included patients with diagnosis of lumbar disc herniation who underwent surgical treatment. Two cohorts were compared: The Open Cohort Approach, comprising patients treated with open access surgical technique and Percutaneous Endoscopic Cohort, comprising patients treated with endoscopic technique. The Propensity score matching (PSM) was applied to balance the cohorts based on demographics (age and sex) body mass index (BMI), comorbidities (such as hypertension, diabetes, and cardiovascular diseases), severity of disc herniation, and history of prior treatments. Results: Our study initially included 5,428 patients in the Open approach cohort and 544 patients in the Percutaneous endoscopic cohort. After applying PSM, the final cohorts comprised 381 and 274 patients, respectively. The risk analysis for recurrence of lumbar disc herniation showed that the risk difference was -0.049 (95% CI: -0.131 to 0.034, p = 0.200). The test statistic (t = -0.983, df = 26, p = 0.335) indicated that there was no significant difference in the rates of disc herniation recurrence between the two groups. Conclusion: The findings of this study suggest that both open surgery and percutaneous endoscopic surgery are viable and safe options for the treatment of lumbar disc herniation, with no significant differences in terms of postoperative complications and recurrence.

ID: 587

RF260: Lumbar tubular decompression: barriers and limitations hampering the technique's dissemination across Latin America

Alberto Gotfryd ¹ , Matias Pereira Duarte ² , Daniel Raskin ³ , Cristian Ricardo Correa Valencia ⁴ , Facundo Van Isseldyk ⁵ , Alfredo Guiroy ⁶

¹ Santa Casa of São Paulo Medical School and Hospitals, Orthopedics, São Paulo, Brazil,

² Hospital Italiano de Buenos Aires, Rosario, Argentina,

³ Santa Casa of São Paulo Medical School and Hospitals, São Paulo, Brazil,

⁴ University of La Frontera, Traumatology Department, Temuco, Chile,

⁵ Hospital Privado de Rosario, Neurosurgery Department, Rosario,, Argentina,

⁶ Elite Spine Health and Wellness, Spine Department,, Fort Lauderdale, United States

Introduction: Lumbar tubular surgery is a popular minimally invasive surgical option for the treatment of lumbar disk herniation and spinal stenosis. Though such operations do not require implantable devices, several specific surgical tools and other pieces of equipment are required, which may increase the final cost of the procedure and could arise as barriers to the widespread use of these techniques in developing countries. Surgeons are often forced to perform surgical adaptations to reduce costs, which could affect the procedures' effectiveness and increase the risk of surgical complications. The use of tubular retractors for lumbar decompression was first described by Foley et al, and their use has gained worldwide popularity over the past 20 years. Several advantages of this approach have been reported, including lower infection rates and faster recovery times. Recently, AO Spine published a 10-step guide for tubular decompression to standardize and facilitate the utilization of these procedures. There is a minimum operating room setup required for this type of surgery, which includes a set of tubular retractors, microscopic or loupe magnification, a high-speed drill, hemostatic agents, and bayonetted instruments, among others. Additionally, surgeons must be trained to perform surgeries in a reduced field, and a steep learning curve has been described. The present study aimed to identify major barriers and limitations restricting the widespread utilization of tubular spine decompressions (TSDs) in Latin America. This can be considered the first regional publication to recognize a list of priorities and limitations for tubular surgeries spanning several countries in this region. The authors believe this is a first step toward developing future strategies focused on facilitating the dissemination of such operations in developing countries in a safe and economically viable way. Material and Methods: A cross-sectional study was performed using a survey designed specifically by the authors. This survey was mailed to all spine surgeons who are members of AO Spine Latin America. Eighty-seven surgeons from 15 countries (Brazil, Argentina, Bolivia, Chile, Colombia, Costa Rica, Ecuador, Guatemala, Mexico, Nicaragua, Panama, Dominican Republic, Uruguay, Venezuela, and Peru) who claimed to have performed at least 30 tubular decompressions were included in the analysis. Results: Thirty-one percent of participating surgeons claimed they needed to adapt their technique to perform minimally invasive tubular surgeries. Meanwhile, though 70.5% answered they do not consider tubular surgery expensive, 32.8% lacked access to standard equipment like a complete set of retractors or curved high-speed drill. Conclusion: Several barriers limit the development of tubular spine surgery in Latin America. The most important discrepancies between surgeons' preferred equipment and their availability for such operations are high-speed drills, bayoneted instruments, and hemostatic agents.

ID: 2297

RF261: Systematic literature review on classifications and surgical decision making in primary spinal infections

Emiliano Vialle ¹ , Andrés González ² , Marcelo Duarte ² , Otávio Vitório Alvarenga Pereira ¹ , Vinícius Lopes Fruet ¹ , Luis Felipe Pereira ³ , João Victor Nascimento Ferreira ³ , Paulo Meira ¹

¹ Pontifícia Universidade Católica do Paraná, Hospital Universitário do Cajuru, Orthopedics and Traumatology Service Spine Surgery Group, Curitiba, Brazil,

² Clinical Medcal Proinfo, Bogotá, Colombia,

³ Pontifícia Universidade Católica do Paraná, Curitiba, Brazil

Introduction: Primary spinal infections encompass pathologic processes including discitis, vertebral osteomyelitis, epidural abscess, intramedullary abscess, and subdural empyema. Surgical decision-making is multifactorial and there is not a perfect algorithm or fluxogram that might lead both clinicians and surgeons towards a better and standardized treatment. Different classifications have focused on separate aspects of spinal pathology and patient characteristics, without a strong reliability or comparison between them. This study aims to identify classifications and treatment algorithms that lead to a more objective decision-making process on the treatment of spinal pyogenic primary infections. Material and Methods: A systematic literature review was performed in English, Spanish, Portuguese, and German - using databases such as Cochrane, Embase, PubMed, Lilacs. Keywords included: “Decompression”, “Decompression Surgical”, “Spine”, “Discitis”, “Osteomyelitis”, “Spinal Fusion”, “Spinal Diseases” covering the years 2003 to 2023. Case reports, letters to the editor and articles in languages other than those specified were excluded primarily Articles that did not correlate with the purpose of this study by title and abstract were also removed. Finally, we have evaluated the confidence and quality of the evidence with the CASP tools, and a scoring system was applied over the selected articles. Results: Of the 697 papers in the databases 193 were excluded based on title, and 478 were excluded after the author’s review. At the end 26 articles were evaluated by the CASP tool, and 17 were considered for inclusion. Finally, a score was applied in the remaining 17 articles to evaluate the overall reliability. These articles have allowed the authors to identify 13 domains that might be relevant to the management of spinal pyogenic infections. Five studies provided a scale to assist in surgical indication and were compared and ranked according to their domains. Conclusion: This systematic review identified key factors that might lead to a better comprehension of the factors influencing surgical decision-making in primary spinal infections, and the need for improvement on the definition of spinal instability in infections. The findings provide a basis for developing more standardized and reliable treatment algorithms.

ID: 2570

RF262: Comparison of antimicrobial prophylaxis protocols of clindamycin and cefazolin in preventing surgical site infection in spine surgery

Emiliano Vialle ¹ , Paulo Meira ¹ , Vinícius Lopes Fruet ¹ , Otávio Vitório Alvarenga Pereira ¹ , João Victor Nascimento Ferreira ² , Luis Felipe Pereira ²

¹ Pontifícia Universidade Católica do Paraná, Hospital Universitário Cajuru, Orthopedics and Traumatology Service, Spine Surgery Group, Curitiba, Brazil,

² Pontifícia Universidade Católica do Paraná, Curitiba, Brazil

Introduction: Surgical site infections (SSIs) are one of the most feared complications in orthopedic surgeries, particularly in spine surgeries, where the consequences can be severe, leading to prolonged hospital stays, the need for additional interventions, and compromised patient recovery. Adequate antimicrobial prophylaxis plays a crucial role in reducing the incidence of these infections. Cefazolin, a first-generation cephalosporin, is widely recommended in international guidelines as the preferred choice for surgical prophylaxis in orthopedic procedures due to its efficacy and broad-spectrum activity against common pathogens. However, during the COVID-19 pandemic, shortages and rising costs of cefazolin forced many hospitals to adopt alternatives, such as clindamycin, a lincosamide antibiotic frequently used in patients allergic to penicillins or cephalosporins. In this study, we compared the efficacy of two antimicrobial prophylaxis protocols - cefazolin and clindamycin - in preventing SSIs in spine surgeries performed by the Spine Surgery Group between 2023 and 2024. The aim is to assess whether the temporary substitution of cefazolin with clindamycin, due to pandemic-related circumstances, had a significant impact on postoperative infection rates. Material and Methods: The is a retrospective transversal based in patient`s medical record analysis conducted by the Spine Surgery Group from 2023 to 2024. A total of 886 spine surgeries were analyzed: 251 patients received Clindamycin and 635 patients received Cefazolin. Clindamycin was administered at 600 mg during anesthesia induction with an 8-hour interval post-operatively for 24 hours. Cefazolin was administered at 1 g (or 2 g for > 80 kg patients) during anesthesia induction, with a 12-hour interval post-operatively for 24 hours. Clindamycin use was temporarily adopted due to a shortage and price increase of Cefazolin during the COVID-19 pandemic. All surgeries were performed by the same team of five lead surgeons and two spine surgery fellows. The main outcome measured was the incidence of SSIs, excluding patients with pre-existing infections. Results: The incidence of SSIs was significantly higher in the Clindamycin group (11.2%) compared to the Cefazolin group (0.98%), with a p-value of < 0.05, indicating a statistically significant difference favoring Cefazolin. Conclusion: When compared with other studies, the results align with previous findings that support the superior efficacy of Cefazolin in preventing SSIs in orthopedic surgeries. The Clindamycin protocol, though necessary during the Cefazolin shortage, proved to be less effective in clinical practice. The Cefazolin prophylaxis protocol was significantly more effective in preventing SSIs in spine surgeries compared to the Clindamycin protocol, which showed a considerably higher infection rate.

ID: 1816

RF263: Surgeon preference as a key factor in decision making in degenerative spondylolisthesis

Emiliano Vialle ¹ , Luiz Vialle ¹ , Joana Guasque ¹ , Otávio Vitório Alvarenga Pereira ¹ , Marcelo Molina ² , João Victor Ferreira ³ , Luis Felipe Pereira ³ , Vinícius Lopes Fruet ¹

¹ Pontifícia Universidade Católica do Paraná, Hospital Universitário Cajuru, Orthopedics and Traumatology Service, Spine Surgery Group, Curitiba - PR, Brazil,

² Clinica Alemana, Instituto Traumatológico, Cirugía de Columna, Departamento de Ortopedia y Traumatología, Santiago, Chile,

³ Pontifícia Universidade Católica do Paraná, Curitiba - PR, Brazil

Introduction: Despite its high prevalence, surgical management of degenerative spondylolisthesis is highly controversial. Although some studies have presented similar results comparing fusion and decompression, others have emphasized the need for a better definition of subgroups based on several radiographic characteristics, such as sagittal parameters, facet angulation, anterior displacement and degree of disc degeneration. The decision regarding fusion type and approach is even more controversial, differing from posterolateral fixation to circumferential fusion. This study aims to determine which radiographic factors guide surgical decision-making regarding decompression with or without fusion for lumbar degenerative spondylolisthesis within a group of Latin American spine surgeons. Material and Methods: A questionnaire was created using Google Forms containing 30 representative clinical cases of patients with degenerative spondylolisthesis, presenting images and radiological measurements, and providing the patient's age and sex. All patients exhibited intermittent claudication and mild low back pain associated with the failure of conservative treatment. This questionnaire was sent to 33 spine surgeons from Latin America, who had to choose between maintain conservative treatment, isolated decompression, or decompression associated with arthrodesis. Cluster analysis was applied to identify decision-making profiles among the surgeons, while the Kappa coefficient was used to measure the degree of interobserver agreement. Results: Data analysis revealed the existence of four clusters with high grouping quality and significant variation in treatment preferences. Pattern A (15.2% - clear preference for fusion); B (39.4% - tendency for fusion over decompression); C (39.4% - tendency for decompression over fusion); D (6.1% - clear preference for decompression). Furthermore, overall agreement among the specialists was assessed using the Kappa concordance coefficient. In this study, 33 evaluators resulted in 528 pairs of comparison, which were classified according to Landis JR and Koch GG. Of the 528 comparisons, 43.5% were significant at the 5% level, with 67.7% showing poor and weak agreement; 28.2% were significant at the 1% level, with 50.3% showing poor and weak agreement. For both 5% and 1% significance levels, none showed strong agreement (0%), and only a few showed good agreement (3.1% and 4.7%, respectively). A significance level of 5% was adopted. Statistical analysis was conducted using SPSS software version 26. Conclusion: Despite the radiographic information offered and considering that all cases had the same clinical picture, there was a clear trend for one specific treatment option for most surgeons, allowing for the conclusion that surgeon preference is the key factor on surgical decision making for degenerative spondylolisthesis. This study highlights significant findings regarding the therapeutic decisions of spine surgeons in Latin America. As evidenced by the Kappa coefficient, there is a lack of consensus among surgeons concerning the treatment of this condition, revealing significant divergence in the approaches adopted. The lack of consensus demonstrates the need for standardization in therapeutic guidelines to ensure more consistent and effective management. Thus, the implementation of guidelines could contribute to better preparation in clinical/surgical planning, ultimately enhancing therapeutic outcomes in both the short and long term.

ID: 1233

RF264: Translation and validation into Brazilian Portuguese of the spine oncology study group outcomes questionnaire (sosgoq) for patients with spinal metastases

Guilherme Pajanoti ¹ , Bruno Braga Roberto ¹ , Nelson Astur ¹

¹ Hospital Israelita Albert Einstein, Sao Paulo, Brazil

Introduction: The population of patients with advanced stages of cancer, including metastatic spinal disease, is growing because of better treatment options allowing for longer control of disease. The main goal of treatment for these patients is to improve or maintain their health-related quality of life (HRQOL). The AO Spine Knowledge Forum Tumor patient expectations questionnaire regarding treatment outcomes in spine oncology aims to better align patient expectations before treatment with their subsequent perceptions. So far, the SOSGOQ has been translated and validated in Italian, German, and Thai. Therefore, it is important to translate and validate the questionnaire into Portuguese so that this population can be safely assisted. Material and Methods: In the present study, the translation of the SOSGOQ questionnaire was carried out following the methodology proposed by Beaton et al. The study was divided into two phases: the first being the translation, back-translation, evaluation of the final version, and assessment of the application test. As a first step, two independent translators performed an initial translation from English to Portuguese, both being native Portuguese speakers. A conceptual translation was conducted, avoiding the literal use of words or phrases. This resulted in two Portuguese versions, which were then compared and synthesized by a third linguist into a single optimized version (“preliminary version_1”) in Portuguese. In the second phase, a linguist back-translated “preliminary version_1” into English without access to the original English version. Based on corrections from the back-translation, a “preliminary version_2” in Portuguese was created. Upon completion of this step, a committee consisting of the principal investigator, another research team member, and one of the translators met online to jointly review the final document. Finally, the instrument was validated by a bilingual physician who reviewed the Portuguese questionnaire with 5 patients through cognitive interviews at Hospital with metastases patients. Results: All steps of translation and validation of the SOSGOQ questionnaire were successfully completed. The initial translation by two independent translators resulted in two Portuguese versions, which were synthesized into a single version (“preliminary version_1”). The back-translation process confirmed the accuracy of the conceptual translation, leading to minor adjustments before finalizing “preliminary version_2.” The final document was reviewed by the translation committee, ensuring the questionnaire's linguistic and cultural adaptation. The Portuguese version of the SOSGOQ was applied to 5 patients at Vila Santa Catarina Hospital during cognitive interviews. All patients demonstrated a clear understanding of the questions and responded appropriately, confirming that the scale was easy to comprehend and use in the context of spinal oncology. There were no significant difficulties or ambiguities reported in interpreting the questionnaire. Overall, the patients' feedback supported the validity of the instrument for use with Portuguese-speaking patients. Conclusion: The scale was deemed effective in aligning patient expectations with treatment outcomes, as intended by the original SOSGOQ. The successful adaptation ensures that this tool can now be utilized to assess and manage patients with spinal metastases in Portuguese-speaking populations.

ID: 2005

RF265: Comparative efficacy of endoscopic discectomy versus microdiscectomy for L5-S1 lumbar disc herniation: a meta-analysis of clinical outcomes

Eshita Sharma ¹ , Ayesha Ayesha ² , Kaike Eduardo da Silva Lobo ³ , Beatriz Pomianoski ⁴ , J. Martín Kotochinsky ⁵ , Yan Silva ⁶

¹ David Geffen school of medicine, Los Angeles, United States,

² Shifa College of Medicine, Islamabad, Pakistan,

³ State University of Pará, Belém, Brazil,

⁴ Universidade Nove de Julho, São Paulo, Brazil,

⁵ Universidad Nacional de Cuyo, Mendoza, Argentina,

⁶ Hospital Ortopédico do Estado, Salvador, Brazil

Introduction: Lumbar disc herniation (LDH) is a common cause of back and leg pain. The endoscopic techniques are now available in several countries and is paramount to evaluate which patients would best benefit from the technique. L5-S1 LDH is frequent and usually treated via a straightforward approach through microdiscectomy (MD) or endoscopic discectomy (ED). As the standard MD technique has already proved to be effective and safe, the aim of this meta-analysis is to compare the MD with ED at L5-S1 level. Material and Methods: We systematically searched PubMed, Embase, and Cochrane Central for randomized controlled trials (RCTs) and observational studies comparing patients who underwent LDH surgery with MD or ED for L5-S1 level. Primary outcomes were operative time (OT), recurrency rate (RR), complications and functional outcomes pre and postop were also evaluated (VAS back and leg and ODI at one, six and twelve months postop). Mean differences (MDs) and odds ratio (OR) were used for all outcomes. The p < 0.05 presented a significant statistical result and I² < 40% showed low heterogeneity. Results: Of 3506 articles screened, a total of 4 studies and 264 patients were included, of whom 134 (51%) were treated with MD and 130 (49%) were treated with ED. There were no significant differences between the groups in OT (MD = 2.45, 95% CI [-31.09, 63.74], p = 0.89, I² = 92%), RR (OD = 0.85, 95% CI [0.22, 3.35], I² = 0%). The VAS for back pain at 1 month postop favored the endoscopy group (OD = 0.59, 95% CI [1.06, 0.11], I² = 0%), no difference was found on VAS for leg pain at one month (OD = 0.16, 95% CI [0.78, 1.10], I² = 0%), moreover both groups improved at one, six and twelve months postop evaluation. Conclusion: Our study showed no significant difference in between ED and MD for LDH at the L5-S1 level regarding the outcomes evaluated. At one month, it seems that the ED has less back pain, what would be in line with the concept of a less invasive surgery. At the L5-S1 level, the larger interlaminar space may underpower the benefits from lesser invasive endoscopic surgery, more studies are needed to address if this remains true in a more homogeneous populations on randomized clinical trials.

ID: 2861

RF266: Risk of peritoneal violation in transforaminal endoscopy: an MRI study

Rafael Barreto ¹ , Carlos Almelunge ¹ , Gabriel Pokorny ²

¹ IMAP, Indaiatuba, Brazil,

² Instituto de Patologia da Coluna, São Paulo, Brazil

Introduction: In an attempt to find an ideal entry point for each patient, some authors have proposed the use of preoperative CT or MRI scans to identify the location of the retroperitoneal structures and then assess how horizontal a lateral access could be. However, one of the main difficulties with this analysis is that the retroperitoneal structures move to a more anterior position, between the dorsal position (CT or MRI position) and the prone position (surgical position). The aim of this study is therefore to analyze the position of the retroperitoneal structures and their movement using CT scans in prone and dorsal decubitus, as well as to verify the theoretical risk of retroperitoneal injury at each of the following entry points. Methods: Cross-sectional observational, comparative, non-randomized study. The inclusion criteria was as follows, Patients over the age of 18, who have consented to take part in the study by filling in the free consent form, and who have no medical contraindications to undergoing CT scans. And the exclusion criteria was patients with any pathology that makes it impossible to take the measurements proposed in the study. Patients who, for whatever reason, have a low-quality image exams. The risk of violation of peritoneal content was assessed both in dorsal and ventral decubitus from two different starting points (red line and green line). Data was compiled in a spreadsheet and analyzed using R software. Categorical variables were described as count and percentage. To compare the impact of different entry points in the risk of peritoneal violation a generalized linear mixed model with binomial distribution family was built. To compare the contrasts and obtain estimations of the odds of peritoneal violation, the estimated marginal means contrasts were analyzed. P values lower than 0.05 were deemed significant. Results: 28 patients were included in the work, of those 16 were female (57%), with the mean age of 39 years old. The risk of peritoneal violation in the “red line” approach was significantly greater than the risk of peritoneal violation in the “green line” approach, showing significant difference in every studied level, both in ventral as in dorsal decubitus. The probability estimated by model of peritoneal violation in ventral decubitus (DV) for the “green line” in L1L2 was 5% (1% - 13%), while for the “red line” the estimative was around 83% (68% - 92%), p < 0.0001. Similarly, in the L2L3 level, the “green line” approach had an 1% (0.3% - 3%) risk of peritoneal violation, compared to 53% (33% - 77%) form the “red line”, p < 0.0001. Furthermore, similar discrepancies were noted in L3L4 (0.3% vs. 23%) and L4L5 (0.6% - 38%). Conclusion: The use of the “red line” approach led to a high risk of peritoneal violation, even in the ventral decubitus. On the other hand, the use of the “green line” entry point, led to diminutive risks of violation in the ventral decubitus with estimated probability of peritoneal violation smaller than 2% for every level below L1-L2.

RF16: ADOLESCENT SPINAL DEFORMITY

ID: 482

RF267: Can intraoperative cell salvage reduce the rate of allogeneic transfusion in pediatric spinal deformity surgery?

Vivien Chan ¹ , Geoffrey Shumilak ² , Armaan Malhotra ³ , David Lebel ³ , David Skaggs ¹

¹ Cedars-Sinai Medical Center, Los Angeles, United States,

² University of Saskatchewan, Saskatoon, Canada,

³ University of Toronto, Toronto, Canada

Study Design: Retrospective cohort study. Objectives: The objective of this study was to characterize the association between cell-salvage and allogeneic transfusion rate in pediatric patients undergoing posterior arthrodesis for scoliosis. Methods: NSQIP Pediatric database years 2016-2022 was used. Patients under the age of 18 who received posterior arthrodesis with 7 or more surgical levels for spinal deformity correction were included. Rates of cell-salvage and allogeneic transfusion were determined. We assessed the impact of cell-salvage on the rate of allogeneic transfusion using chi-square test and multivariable logistic regression. Results: There were 34,241 patients in this study. The rate of allogeneic transfusion was 21.6% (n = 7 407). The allogeneic transfusion rates for idiopathic, neuromuscular, and congenital/syndromic scoliosis were 12.3%, 50.8%, and 25.9%, respectively. Cell-salvage was used in 71.1% of patients (n = 24,344). In the multivariable regression analysis, longer operative time (p < 0.001), non-idiopathic scoliosis (p < 0.001), hematocrit less than 35 (p < 0.001), and ≥ 13 surgical levels (p < 0.001) were associated with higher odds of allogeneic transfusion. Use of cell-salvage (p < 0.001), increasing age (p < 0.001), and increasing patient weight (p < 0.001) were associated with significantly lower odds of allogeneic transfusion. In a subanalysis, use of cell-salvage was associated with reduced rate of allogeneic transfusion in patients with idiopathic scoliosis. Cell-salvage was not associated with reduced rates of allogeneic transfusion in neuromuscular and congenital/syndromic scoliosis. Conclusion: This is the largest study investigating the impact of cell-salvage on rate of allogeneic transfusion in pediatric spinal deformity surgery. Use of cell-salvage is associated with reduced allogeneic transfusion rates in idiopathic scoliosis surgery.

ID: 867

RF268: How much residual deformity is acceptable for Lenke 5 adolescent idiopathic scoliosis patients after surgery?

Fang Xie ¹ , Zhuojing Luo ¹ , Xueyu Hu ¹

¹ Xijing Hospital, Xi’an, China

Introduction: To analyze the deformity degree threshold associated with satisfaction in Lenke5 AIS patients based on Scoliosis Research Society scale (SRS-22). Material and Methods: Lenke 5 adolescent idiopathic scoliosis (AIS) patients who underwent surgical treatment at our Hospital from January 2016 to December 2020 were included. All patients were followed up for more than 2 years, and the results of the SRS-22 scale before and at the last follow-up were analyzed. Patients who selected “very satisfied” and “satisfied” in question 21 “Are you satisfied with the effectiveness of your back treatment?” were recorded as having reached the Patient Acceptable Symptom State (PASS), and the thresholds for PASS in the four dimensions of appearance, pain, function, and psychology in the SRS-22 scale were calculated separately. Using residual lumbar deformity degree and general information as independent variables, binary regression analysis was conducted to obtain relevant indicators for achieving PASS status. Receiver operating characteristic curve (ROC) was used to calculate the area and threshold under the curve. Results: 66 patients were included in the study, with an average age of 17.2 years and an average follow-up of 31 months. 45 patients (68.2%) reached PASS status, and the threshold and area under the curve for each dimension of the SRS-22 scale to reach PASS were appearance (4.1 points, 0.824), pain (3.8 points, 0.698), function (4.2 points, 0.723), and psychology (4.0 points, 0.716), respectively. The regression analysis results showed that postoperative lumbar curvature was closely related to the patient's achievement of clinical PASS and appearance PASS, with thresholds of 13.8° and 12.2°, respectively. Conclusion: The residual degree of lumbar curvature is closely related to the satisfactory treatment and appearance of Lenke 5 AIS patients after surgery. When the residual degree of lumbar curvature is ≤ 13.8°, patients are satisfied with the clinical result, and this threshold can be used as a reference indicator for intraoperative correction.

ID: 181

RF269: Outcomes of vertebral column resection in rigid severe adult and pediatric spinal deformities

Mehmet Erkilinc ¹ , Munish Gupta ²

¹ Saint Louis University, St. Louis, United States,

² Washington University in St. Louis, St. Louis, United States

Introduction: Managing severe and rigid spinal deformities are challenging to correct. Vertebral column resection (VCR) is often necessary for adequate correction. Substantial risks remain with blood loss, prolonged operative time and risk to the neural elements. We studied VCR in rigid pediatric and adult spinal deformities including deformity correction, IONM alerts, spinal cord/nerve injuries, and perioperative adverse events Methods: We conducted a retrospective review of 54 patients who underwent VCR for severe and rigid spinal deformities between 2016 and 2022 with min 2 yr F/U. A single surgeon performed all the surgeries. Demographic data, diagnosis, comorbidities, radiographic parameters and all adverse events were collected. Results: Twenty-three pediatric patients average age of 14.25 (9.8 to 20.6) and 31 adult patients with average age of 53.7 (24.4 to 79.7) underwent VCR for either rigid severe scoliosis, kyphosis or short angular deformities. Average BMI was 25.4 ranging (14.6 to 41.7). Average Cobb angle for Scoliotic deformities was 106.9 degree ranging from 66 to 131. Kyphosis was average 90.6 degree (78 to 108). Average flexibility index was 15.7% ± 10.9. Two of pediatric cases and 11 of adult cases were revisions. Average postop correction rate was 68%. Scoliosis was corrected 71.4% and kyphosis was corrected 65.2% The average EBL was 1066 ml (150 to 5500 ml). Seven dural tears were repaired with no short or long term sequelae. Four of 7 pts. who have dural tear were revision cases. The incidence of dural tear in revision cases (30%) significantly higher than primary cases (7%). (p = 0.052). Two patients have pleural rents which were repaired. Six patients have IONM alerts during the surgery, with an incidence rate of 11.1%. Two of 6 patient’s data normalized immediately after optimization of anesthesia technique and blood pressure. Prompt surgical intervention including decreased correction and more decompression was performed on the 4 remaining patients with subsequent reversal of the monitoring change to baseline IONM data and negative wake up tests. One of the patients had loss of bilateral lower extremity MEP signal multiple times, leading to the decision to stage with subsequent successful correction. In the second stage, vertebral resection was carried out without any MEP loss. Conclusions: VCR can be a safe and effective option for correcting rigid and severe spinal deformities as demonstrated by this single surgeon series with averagw scoliosis > 100° and kyphosis > 90°.The average curve flexibility was 15.7% but the average correction rate with VCR was 68%. The incidence of IONM alerts in patients undergoing vertebral column resection was 11.1%. None of the patients suffered from a spinal cord injury with a neurologic deficit intraop and postoperatively.

ID: 1773

RF270: Beyond the Cobb: the preoperative radiographic effects of halo gravity traction in severe spine deformities

Alderico Girão Campos de Barros ¹ , Giancarlo Jorio Almeida ¹ , Gabriel Alves ¹ , Luis Eduardo Carelli Texeira da Silva ¹

¹ INTO, Spine Surgery, Rio de Janeiro, Brazil

Introduction: Severe spine deformities are those which does not correct below 20 to 30% of the initial cobb value in bending tests. Patients with these deformities frequently present for the first time in a reference center with rigid curves, significant humps, cardiorespiratory dysfunction and imbalance of trunk, shoulders, pelvis and lower limbs. The planning and execution of scoliosis surgeries in these patients is challenging and numerous factors should be considered. The management of these patients require the use of diverse strategies, among them is the Halo Gravity Traction (HGT). There is considerable evidence in the literature of the benefits of preoperative HGT in the treatment of complex spinal deformity. The vast majority of them only focus on the improvement of the angular value of the curve. The objective of this study was to evaluate whether the benefits of HGT in these patients improve not only the magnitude of the curve measured by the cobb angle, but also whether there is an improvement in other radiographic parameters related to the balance of shoulders, trunk, pelvis and lower limbs. Material and Methods: Retrospective study carried out by review of medical records and radiographic images of patients with severe spinal deformity treated with preoperative HGT in a reference center from 2017 to 2023. Patients with all curve etiologies were included. Cases with deformity less than 100 degrees, use of traction only during surgery or between surgical stages, as well as patients with less than 2 weeks of traction were excluded. Only the results of the initial x-rays and the final preoperative HGT x-rays were considered. The study did not compare surgical results. The data were assessed for normality using the Kolmogorov-Smirnoff test. Paired T or Wilcoxon tests was used to compare pre and post HGT values ​​of numerical variables. A p-value ≤ 0.05 was considered significant. Results: Of the 7 male and 8 female patients who underwent HGT during the study period, none were excluded. The patients’ ages ranged from 9 to 32 years, with an average of 16.9 years, while the traction time ranged from 14 to 55 days, with an average of 39.1 days. Coronal cobb reduced on average 22.2%, while the sagittal cobb showed reduction of 21.3% on average. A statistically significant reduction was found between the pre- and post- traction values of curve angulation using the Cobb method for the proximal thoracic, main thoracic, and thoracolumbar or lumbar curves; the Clavicular Angle; the Apical vertebra Translation; The coronal Balance; the Thoracic Trunk Shift; the Leg Length discrepancy, the Sacral Obliquity; the Pelvic Obliquity through both Maloney and Osebold methods; the Thoracic Coronal Alignment; and Sagittal Cobb. No statistically significant difference was found between pre- and post-HGT regarding T1 Tilt Angle, SVA, and spinopelvic parameters. Conclusion: The benefits of preoperative halo gravity traction in patients with severe spinal deformities include not only the reduction in the angular value of the curve, but also the improvement in radiographic parameters related to the balance of the shoulders, trunk, pelvis and lower limbs.

ID: 2268

RF271: Evaluating the impact of iron deficiency in adolescent scoliosis surgery

Annie Qiu ¹ , Yona Feit ¹ , Fthimnir Hassan ¹ , Daysha Fliginger ¹ , Guohua Li ¹ , Lawrence Lenke ¹ , Eldad Hod ¹ , Lisa Eisler ¹

¹ Columbia University Irving Medical Center, New York, United States

Introduction: Iron is essential to the functioning of red blood cells and many other cell types. Iron deficiency (ID) is the leading cause of anemia worldwide, and in addition contributes to reduced physical and cognitive performance. Adolescents undergoing spinal fusion surgery for scoliosis are not routinely screened for ID, though their growth and development increase the body’s demand for iron while surgery-related bleeding and inflammation lead to further losses and iron sequestration. Therefore, this study aimed to better characterize the burden of ID in this vulnerable population. Methods: Patients undergoing a primary posterior spinal fusion surgery for scoliosis at MSCHONY were prospectively enrolled in an observational cohort study of RBC and iron parameters from preoperative evaluation through surgical recovery. Baseline characteristics, clinical laboratory findings, and RBC transfusion events were obtained from the electronic medical record, while history of iron supplementation was provided by patient/parent report. Research specimens drawn at presentation for surgery and at a surgery clinic follow-up visit serum ferritin and soluble transferrin receptor concentration (sTfR), as well as RBC indices and other iron parameters. ID was defined as a ferritin < 25 µg/L and/or sTfR > 4.4 mg/L. Anemia was defined as Hg < 12 g/dL for females and < 13 g/dL for males. Proportions were compared using Fisher’s exact test. Results: This study enrolled 46 participants (13 males and 33 females) ranging in age from 11 to 18 years between September 2021 and August 2023. Baseline anemia was present in 17.4% (n = 8/46) of patients. 13% (n = 6) reported taking an iron supplement preoperatively. The rate of ID on presentation for surgery was 33.3% (n = 14/42). RBC transfusion occurred in 10.8% (5/46) of patients, with iron deficient patients being transfused more commonly than non-iron deficient patients (35.7% vs. 0.0% respectively, p = 0.0024). In samples obtained 6-8 weeks postoperatively (n = 24), iron deficiency was present in 73.9% of patients overall, while anemia was present in 50%. Conclusions: Preoperative ID was observed in one third of adolescents presenting for scoliosis surgery at our institution and was associated with a higher likelihood of RBC transfusion. At 6 to 8 weeks after spinal fusion surgery, the vast majority of patients were iron deficient, and most demonstrated abnormal RBC and/or other iron parameters. Given the high burden of disease, its potential impact on RBC transfusion, as well as the lack of supplementation under the current standard of care, these data indicate the need for future studies examining the potential benefits of perioperative iron therapies and call for us to examine the extent of preventable perioperative harm.

ID: 140

RF273: L3 Versus L4 as the lowest instrumented vertebra in posterior instrumented spinal fusion for Lenke lumbar modifier C adolescent idiopathic scoliosis: a case series, systematic review, and meta-analysis

Yilong Zheng ¹ , Vikaesh Moorthy ¹ , Reuben Soh ¹

¹ Singapore General Hospital, Singapore, Singapore

Introduction: The optimal lowest instrumented vertebra (LIV) for patients with Lenke lumbar modifier C adolescent idiopathic scoliosis (AIS) is controversial. This study aimed to compare the outcomes between patients with L3 and L4 as the LIV after posterior instrumented spinal fusion for Lenke lumbar modifier C AIS. Material and Methods: PubMed and Embase were systematically reviewed and patients operated on by the senior author between 2015 and 2022 were included. The exposure was the LIV, defined as either L3 or L4. The outcomes were the Scoliosis Research Society-22 questionnaire (SRS-22) scores, peak lumbar flexion and extension, and radiographic parameters at the latest follow-up. Radiographic parameters analyzed included the thoracolumbar/lumbar (TL/L) Cobb angle, LIV tilt (LIVT), coronal balance, and lumbar lordosis on erect radiographs. Results: Of the 186 articles screened, 6 studies reporting 575 patients and 31 patients from our cohort were included in the meta-analysis. Most patients had L3 as the LIV (393 patients, 64.9%), and the estimated pooled mean (SD) age at surgery and follow-up duration were 15.3 (3.7) and 3.8 (1.6) years respectively. Patients with L3 as the LIV had significantly better SRS-22 function/activity scores than patients with L4 as the LIV at the latest follow-up (MD = 0.18; 95% CI = 0.02 to 0.34). Patients with L3 as the LIV also had greater peak lumbar flexion (mean 31.2 vs 28.5 degrees; p = 0.820) and extension (mean 19.8 vs 16.8 degrees; p = 0.820) at the latest follow-up, though these differences were not statistically significant. There were no significant differences in radiographic outcomes between the L3 and L4 LIV groups except for lumbar lordosis (MD = 1.83; 95% CI = 0.19 to 3.47) at the latest follow-up. Preoperatively, patients in the L3 LIV group had significantly lower curve severity as defined by the TL/L Cobb angle (MD = -3.25; 95% CI = -5.05 to -1.46), LIVT (MD = -1.92; 95% CI = -3.82 to -0.01), and coronal balance (MD = -2.70; 95% CI = -5.26 to -0.15). Conclusion: Among patients who underwent posterior instrumented spinal fusion for Lenke lumbar modifier C AIS, patients who had L4 as the LIV achieved greater curve correction but also experienced significantly greater functional morbidity than patients with L3 as the LIV at the latest follow-up. Range of motion was not significantly affected irrespective of the LIV in our population.

ID: 343

RF274: Will the growing rod surgery change the cervical balance in the treatment of early onset scoliosis? A case-control retrospective study based on machine learning algorithms

Bo Han ¹ , Junrui Jonathan Hai ² , Yong Hai ^1,3

¹ Beijing Chaoyang Hospital, Capital Medical University, Orthopedic Surgery, Beijing, China,

² Princeton International School of Math and Science, Princeton, United States,

³ Center for Spinal Deformity, Capital Medical University, Beijing, China

Introduction: This study aimed to analyze the changes in cervical sagittal alignment following growing rod treatment in early-onset scoliosis (EOS) and to identify risk factors for cervical sagittal imbalance using machine learning techniques. Material and Methods: We conducted a retrospective review of EOS patients treated at our center between 2007 and 2019. Radiographic parameters assessed included cervical lordosis (CL), T1 slope, C2-C7 sagittal vertical axis (C2-7 SVA), primary curve Cobb angle, thoracic kyphosis (TK), C7-S1 sagittal vertical axis (C7-S1 SVA), and proximal junctional angle (PJA). These parameters were evaluated at three time points: preoperatively, postoperatively, and at the final follow-up. Statistical analyses were performed using t-tests and χ2 tests. Additionally, we applied the machine learning methodology of Sparse Additive Models (SAM) to identify risk factors contributing to cervical sagittal imbalance. Results: A total of 138 patients (96 males and 42 females) were included in this study. The average thoracic curve Cobb angle was 67.00 ± 22.74°, and the mean age at the time of the first surgery was 8.5 ± 2.6 years. The mean follow-up duration was 38.48 ± 10.87 months. Significant increases in CL, T1 slope, and C2-7 SVA were observed at the final follow-up compared to preoperative values (p < 0.05). Patients who developed proximal junctional kyphosis (PJK) postoperatively exhibited more pronounced increases in CL and T1 slope than those without PJK (p < 0.05). The location of the upper instrumented vertebrae (UIV) and whether single or dual growing rods were used did not significantly influence sagittal cervical parameters (p > 0.05). Machine learning analysis using SAM identified postoperative PJK, greater improvement in kyphosis, and increased T1 slope as significant risk factors for developing cervical sagittal imbalance during growing rod treatment. Conclusion: Growing rod surgery in EOS significantly impacts cervical sagittal alignment. The development of postoperative PJK, along with greater correction of kyphosis and increased T1 slope angle, were identified as key risk factors for cervical sagittal imbalance. These findings highlight the importance of carefully monitoring cervical alignment and considering these risk factors in the surgical planning and postoperative care of EOS patients undergoing growing rod surgery.

ID: 1260

RF275: Mechanical complications following long segments spinal fusion for degenerative kyphosis: what are the failure mode of each patterns of imbalance?

Yong Qiu ¹ , Zhen Liu ¹ , Li Jie Li Jie ¹ , Zhen Tian ¹ , Dongyue Li ¹ , Xiaodong Qin ¹ , Zhong He ¹ , Zezhang Zhu ¹

¹ Nanjing Drum Tower Hospital, Affiliated Hospital of Medical School, Division of Spine Surgery, Department of Orthopedic Surgery, Nanjing, China

Objective: This study aims to investigate the correlation between preoperative sagittal plane morphology, bone and muscle degeneration indicators, and the patterns of proximal junctional kyphosis (PJK) occurrence in adult patients undergoing long-segment spinal deformity correction and fusion surgery. Methods: We conducted a retrospective analysis of 190 patients with degenerative spinal deformity who underwent posterior long-segment instrumentation with S2AI screws between January 2016 and January 2019. Patients who developed PJK within 2 years postoperatively were included. Based on the pattern of PJK occurrence, patients were categorized into three groups: single-segment collapse group (S group), multi-segment degeneration group (M group), and proximal junctional failure group (F group). Preoperative, immediate postoperative, and 2-year follow-up standing whole spine X-rays were analyzed to measure and record Cobb angle, coronal balance distance (CBD), global kyphosis (GK), thoracic kyphosis (TK), lumbar lordosis (LL), sagittal vertical axis (SVA), proximal junctional angle (PJA), T1 pelvic angle (T1PA), pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), and PI-LL. Differences in imaging parameters, vertebral bone quality score (VBQ), and paravertebral muscle fat infiltration rates were analyzed among the three groups. Results: Among all patients, 55 developed PJK, yielding an incidence rate of 28.9%. The M group accounted for 74.5%, the S group for 10.9%, and the F group for 14.5%. In the M group, 85% of patients had the peak kyphosis located in the thoracic spine (TL), whereas 67% of the S group had the peak kyphosis below L2. In the S group, 50% of the upper-end fixation levels were below T10, which was significantly lower than in the M group. The F group had a significantly higher incidence of overall SVA imbalance (SVA > 5 cm) compared to the M group, at 67%. Compared to the S and M groups, the F group exhibited significantly increased VBQ scores and higher rates of paravertebral muscle fat infiltration (VBQ score: F group 3.4 vs. M group 3.0 vs. S group 2.75; paravertebral muscle fat infiltration rate: F group 40% vs. M group 36% vs. S group 29%), with statistically significant differences (p < 0.05). Conclusion: Postoperative PJK in degenerative spinal deformity patients is predominantly characterized by multi-segment symmetrical degeneration. Patients with preoperative imbalance and significant bone and paravertebral muscle degeneration have a higher risk of proximal junctional failure.

ID: 2310

RF276: Predictive significance of axial plane parameters in coronal plane correction in vertebral body tethering (VBT) patients

Kai Chun Augustine Chan ¹ , Anjaly Saseendran ¹ , Kenny Yat Hong Kwan ¹

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

Introduction: Previous studies have investigated mainly on coronal plane correction in vertebral body tethering (VBT) but not the axial plane. This retrospective radiographic study aims to investigate the 3D changes in VBT patients with minimum of 2-years follow-up and determine the relationship between preoperative 3D parameters and postoperative changes, especially those involving axial parameters. Material and Methods: A total of 25 major curves in 21 patients (5 males, 16 females), with a mean follow-up of 33.1 months (range: 24 to 54 months) were analysed. All patients underwent VBT between Feb 2019 to Jan 2022, with average age of 12.0 ± 1.3 at time of surgery. 3D reconstructions with EOS® radiographs (EOS® imaging, Paris, France) of patients were created for pre-op, immediately post-op, 1- year post-op and 2-years post-op films, obtaining relevant 3D parameters for analyses of trend and relationships. Radiographic outcomes include changes of coronal, axial, sagittal and spinopelvic parameters from pre-op to immediately post-op, 1-year and 2-years post-op respectively. Axial parameters assessed were apical vertebral rotation (AVR), maximal vertebral rotation (MVR) and torsion index (TI). Relationships were assessed between preoperative parameters and 3D changes at 1-year and 2-years postoperatively, especially those between preoperative AVR, MVR and TI with magnitude of curve regression and percentage curve correction (i.e. correction rate). Linear regression analysis was performed to assess these relationships. Complications including tether breakage, overcorrection and pulmonary were recorded for our cohort. Results: Mean major Cobb angle was 51.4 ± 12.5 degrees (°) pre-op and improved to 24.5 ± 7.6° immediately post-op, which was maintained at 23.5 ± 10.1° at 2-years post-op (p < 0.001). Mean AVR was 10.4 ± 5.5° preoperatively and achieved immediate correction to 6.6 ± 5.1° postoperatively, which was maintained at 7.2 ± 6.2° at 2-years post-op (p = 0.036). Mean MVR improved from 15.7 ± 5.2° to 11.3 ± 4.7° post-op and was maintained at 12.6 ± 5.8° at 2 years (p = 0.001). There were minimal changes in thoracic kyphosis (p = 0.478) and lumbar lordosis (p = 0.909). Sagittal pelvic tilt increased progressively from 3.0 ± 7.6° pre-op to 9.0 ± 7.9° at 2-years (p = 0.027). Higher pre-op MVR was predictive of greater magnitude of curve regression at 1-year (B(beta coefficient) = 1.19; R square(²) = 0.24; p = 0.013) and 2-years (B = 1.44; R² = 0.26; p = 0.009). Similar association was shown with pre-op AVR at 1-year (B = 1.26; R² = 0.29; p = 0.006) and 2-years (B = 1.76; R² = 0.41; p < 0.001). Pre-op AVR was also predictive of correction rate at both 1-year (B = 2.09; R² = 0.20; p = 0.024) and 2-years (B = 2.54; R² = 0.25; p = 0.012). Post-op pulmonary complications (pleural effusion and pneumothorax) were seen in 3 patients while there were 6 patients with asymptomatic tether breakage between post-op one and 2-years. From post-op 1-year to 2-years, there was worsening of both MVR (+5.8 ± 4.5° VS +1.0 ± 5.0°; p = 0.031) and AVR (+5.0 ± 5.5° VS -1.2 ± 6.0°; p = 0.021) in these patients compared to those with intact tether. Conclusion: VBT was showed to be significantly effective in correcting coronal deformity in 2-years and could reduce severity of axial rotations. Further, axial parameters, in particular MVR and AVR, showed predictive value in determining degree of curve regression in our patients, with increased axial rotation associated with greater coronal correction. While success in VBT is multifactorial, VBT could be considered even in patients with severe pre-op axial rotations.

ID: 2348

RF278: Can multimodal large models become screening tools for scoliosis?

Junxiao Su ¹ , Yang Yang ¹ , Hui Zhang ¹

¹ Gansu Provincial Hospital, Lanzhou, China

Introduction: This study evaluated the capabilities of three representative multimodal large models, Chatgpt-4, Minigpt-4, and Owl-2, in identifying scoliosis imaging, aiming to explore the potential application of multimodal large models in the field of orthopedics, especially in scoliosis screening, and to provide early exploration for the clinical use of multimodal large models. Material and Methods: The study used a retrospective design, employing a total of 60 open-source database-backed photos of the human back (30 from patients with spinal deformities and 30 from normal controls). Two experienced spinal surgeons conducted a detailed assessment of the patients' back photos and medical histories to determine the presence of spinal deformities and classified them into Cobb angle groups: less than 15°, 15°-40°, and greater than 40°. The images from each group were presented to Chatgpt-4, Minigpt-4, and Owl-2 in a question-and-answer format, and the models' judgments or tendencies regarding the presence of scoliosis in the patient were extracted from their responses. Due to the equivocal nature of the large models' answers, only the AI's first response after clearing all context was used. Descriptive statistics were performed on whether the three models answered correctly and the time required for their responses. The results of the large model interpretations of the back images were compared with the diagnoses given by human experts to calculate the accuracy, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the specific model in screening for scoliosis. Additionally, the study assessed the impact of the degree of curvature on the diagnostic results. Results: The sensitivity of ChatGPT-4 in diagnosing scoliosis was 63.33%, and the specificity was 76.67%. Minigpt-4 had a sensitivity of 56.67% and a specificity of 70.0%, while Owl-2 had a sensitivity of 60.0% and a specificity of 66.67%. In diagnosing the group with a Cobb angle greater than 40°, all three models achieved the highest sensitivity at (0.8 vs 0.8 vs 0.7) and specificity at (0.9 vs 0.8 vs 0.8). There was a significant difference in the sensitivity of the large models in diagnosing different groups. Conclusion: Multimodal large models showed variable diagnostic performance in interpreting back images of scoliosis patients, demonstrating higher accuracy in more severe cases of curvature. However, the results also revealed challenges faced by multimodal large models in clinical diagnosis and patient screening applications, especially in improving sensitivity in patients with milder degrees of curvature. To make large models more reliable and widely applicable in medical diagnosis, further training, parameter tuning, and optimization on specific disease datasets are required. Although large models have shown some potential for application in certain situations, significant progress in sensitivity and specificity is needed before they can be considered reliable tools for clinical diagnosis.

ID: 627

RF279: Is the information provided by large language models valid in educating patients about adolescent idiopathic scoliosis? An evaluation of content, clarity and empathy. The perspective of the European Spine Study Group

Siegmund Lang ^1,2 , Jacopo Vitale ³ , Fabio Galbusera ³ , Tamas Fekete ² , Louis Boissiere ⁴ , Yann Philippe Charles ⁵ , Altug Yucekul ⁶ , Caglar Yilgor ⁶ , Susana Núñez-Pereira ⁷ , Sleiman Haddad ⁷ , Alejandro Gomez-Rice ⁷ , Jwalant Mehta ⁸ , Javier Pizones ⁹ , Ferran Pellisé ¹⁰ , Ibrahim Obeid ⁴ , Ahmet Alanay ⁶ , Frank Kleinstuck ² , Markus Loibl ²

¹ University Hospital Regensburg, Trauma Surgery, Regensburg, Germany,

² Schulthess Clinic Zurich, Spine Surgery, Zurich, Switzerland,

³ Schulthess Clinic Zurich, Spine Center, Zurich, Switzerland,

⁴ Hôpital Pellegrin Bordeaux, Spine Unit Orthopaedic Department, Bordeaux, France,

⁵ Hôpitaux Universitaires de Strasbourg, Spine Surgery, Strasbourg, France,

⁶ Acibadem Mehmet Ali Aydinlar University, Department of Orthopedics and Traumatology, Istanbul, Türkyie,

⁷ Vall d'Hebron University Hospital, Spine Research Unit, Barcelona, Spain,

⁸ Royal Orthopaedic Hospital UK, Spine Surgery, Birmingham, United Kingdom,

⁹ La Paz University Hospital, Spine Unit Orthopaedic Department, Madrid, Spain,

¹⁰ Vall d'Hebron University Hospital, Spine Surgery Unit, Barcelona, Spain

Introduction: Large Language Models (LLM) have the potential to bridge knowledge gaps in patient education and enrich patient-surgeon interactions. This study evaluated three chatbots for delivering empathetic and precise Adolescent Idiopathic Scoliosis (AIS) related information and management advice. Specifically, we assessed the accuracy, clarity, and relevance of the information provided, aiming to determine the effectiveness of LLMs in addressing common patient queries and enhancing their understanding of AIS. Material and Methods: We sourced 20 web pages for the top frequently asked questions (FAQs) about AIS and formulated 10 critical questions based on them. Three advanced LLMs - ChatGPT 3.5, ChatGPT 4.0, and Google Bard -were selected to answer these questions, with responses limited to 200 words. The LLMs´ responses were evaluated by a blinded group of experienced deformity surgeons from seven spine centers. A pre-established 4-level rating system from excellent to unsatisfactory was used with a further rating for clarity, comprehensiveness, and empathy on the 5-point Likert scale. If not rated “excellent” the raters were asked to report the reasons for their decision for each question. Lastly, raters were asked for their opinion towards AI in healthcare in general in 6 questions. Results: The responses among all LLMs were 'excellent' in 26% of responses, with ChatGPT-4.0 leading (39%), followed by Bard (17%). ChatGPT-4.0 was rated superior to Bard and ChatGPT 3.5 (p = 0.003). Discrepancies among raters were significant (p < 0.0001), questioning inter-rater reliability. No substantial differences were noted in answer distribution by question (p = 0.43). The answers on diagnosis (Q2) and causes (Q4) of AIS were top-rated for clarity, while outcomes (Q7) and cosmetic corrections (Q9) had lower 'excellent' ratings. The most dissatisfaction was seen in the answers regarding definitions (Q1) and long-term results (Q7). Exhaustiveness, clarity, empathy, and length of the answers were positively rated (> 3.0 on 5.0) and did not demonstrate any differences among LLMs. However, GPT-3.5 struggled with language suitability and empathy, while Bard's responses were overly detailed and less empathetic. Overall, raters found that 9% of answers were off-topic and 22% contained clear mistakes. Conclusion: Our study offers crucial insights into the strengths and weaknesses of current LLMs in AIS patient and parent education, highlighting the promise of advancements like ChatGPT-4.0 alongside the need for continuous improvement in empathy, contextual understanding, and language appropriateness.

ID: 282

RF280: Does pelvic fixation in neuromuscular scoliosis correction affect functional ability? A systematic review and meta-analysis

Rodrigo Muscogliati ^1,2 , Weronika Nocun ¹ , Mohammad Daher ¹ , Elie Najjar ¹ , Shakil Patel ¹ , Ahmed Hassan ^1,3 , Nasir Quraishi ¹

¹ Queen's Medical centre, Nottingham University Hospitals, Nottingham, United Kingdom,

² Hull-York Medical School, Hull, United Kingdom,

³ Department of Orthopedics and Trauma Surgery, Assiut University School of Medicine, Assiut, Egypt

Background: Neuromuscular scoliosis (NMS) often involves pelvic obliquity and surgical correction may encompass instrumenting to the pelvis. However, there is no clear consensus whether such extended fixation and fusion negatively impacts walking ability and function post operatively. Purpose: Assess the influence of pelvic fixation as a part of scoliosis correction in patients with NMS on postoperative function. Study design: Systematic review of literature. Methods: A systematic review of the English language literature using Pubmed, Embase and Cochrane and dating up until November 2023 was undertaken following Preferred Reporting Items for Systematic Review and Meta-Analysis guidelines. Results: Five papers (Level III evidence) were relevant from a pool of 297 initial studies. A total of 120 NMS patients with an average age of 15.8 years (M/F = 0.87) underwent surgical correction with pelvic fixation. The preop Cobb’s angle was 62.8° and pelvic tilt was 16.5°. Average blood loss was 2851 ml, and hospital stay was 19 days. The 2 year post op Cobb’s angle and pelvic tilts were 32.4° and 8.6° consecutively. With an average follow-up of 30 months, the number of major complications was 29. A total of 110 NMS patients with an average age of 15.6 years (M/F = 1.08) underwent surgical correction without pelvic fixation. The preop Cobb’s angle was 76.7° and pelvic tilt was 16.8°. average blood loss was 1383 ml, and hospital stay was 21 days. The 2 year post op cobb’s angle and pelvic tilts were 29.4° and 11.5° consecutively. With an average follow-up of 36 months, the number of major complications was 34. Each study used a different scoring system for function and mobility. There was no significant changes in both groups regarding changes in functional ability (0.1 vs 0 (p = 0.65)), SF36 (7.6 vs 3.6 p = 0.007), GMFCS (0.8 vs 0.9 p = 0.18). In addition, statistical analysis showed no significant difference in blood loss (p = 0.17), hospital stay (p = 0.67), preoperative and 2 year follow-up cobb’s angle (p = 0.06 and p = 0.54), preop and 2 year follow-up PT (p = 0.3 and p = 0.5) and rate of major complications (p = 0.55). Conclusion: Comparing patients undergoing NMS correction surgery with and without pelvic fixation showed no significant difference in blood loss, hospital stay, radiological parameters and functional outcomes.

ID: 1862

RF281: Modified halo-pelvic traction combined with bilateral growth rod implantation in the treatment of severe early-onset scoliosis in children: a report of two cases

Jianming Zhang ¹ , Lei Yue ¹ , Haolin Sun ¹

¹ Peking University First Hospital, Beijing, China

Introduction: Early onset scoliosis (EOS) refers to the age of onset of scoliosis in patients less than 10 years old. EOS covers a wide range. According to different etiologies, it can be divided into congenital scoliosis, neuromuscular scoliosis, idiopathic scoliosis in infants and young children, and other spinal deformity syndromes. The treatment of children with EOS should not only meet the needs of orthopedics with the growth of children's age, but also meet the needs of children's spine growth and lung and other important organ development. At present, there is still a lack of unified and effective treatment strategies for children with severe EOS. Material and Methods: This study reports the diagnosis and treatment process of two Tibetan children (a 5-year-old male child and a 6-year-old female child) who received treatment in Taiyuan district of Peking University First Hospital and the Central District of Peking University First Hospital. After the two children were admitted to the hospital, various examinations were improved, and a modified Halo-pelvic traction was performed one week after admission. The modified Halo-pelvic traction is characterized in that the telescopic connecting rod is designed at the front and outside of the patient's trunk to avoid the traditional head basin ring from hindering the patient's normal dressing and supine rest. Two children underwent secondary spinal adjustable device implantation (bilateral growth rods) with satisfactory traction effect after 10 weeks of traction. The observation indexes of this study were mainly based on the imaging data to evaluate the parameters of scoliosis improvement: coronal Cobb angle, apical vertebral offset, sagittal thoracic kyphosis angle, T1-S1 height, and to record the complications of children in the traction process. Results: Two children did not experience any complications such as instrument related infection or nerve damage during the four month new head pelvic ring traction. By comparing the imaging data of the pediatric patients before, after, and after the modified halo-pelvic traction, it was found that there was a significant improvement in scoliosis after traction and surgery compared to before traction (p < 0.05). Male pediatric patients had a Cobb angle of 140.4° before traction, 75.5° after traction, and 82.4° after surgery; Female pediatric patients had a Cobb angle of 125.2° before traction, 63.2 ° after traction, and 48.9° after surgery. The sagittal thoracic kyphosis angle in male patients is 90.5° before traction, 67.1° after traction, and 35.8° after surgery; Female pediatric patients have a thoracic kyphosis angle of 60.4° before traction, 40.5° after traction, and 38.4° after surgery. Although the improvement of coronal Cobb angle in male patients after surgery was slightly lower than that after traction, the difference was not statistically significant (p > 0.05). Conclusion: The modified halo-pelvic traction combined with bilateral growth rod implantation technology has shown satisfactory clinical efficacy in the treatment strategy, providing an implementable treatment option for children with severe EOS.

ID: 333

RF282: Outcome of posterior spinal fusion for management of adolescent idiopathic scoliosis in Nigeria

Mutaleeb Shobode ^1,2 , Oladapo Ekundayo ³ , Lukman Ajiboye ⁴ , Misbahu Ahmad ⁵ , Mohammed Kabir Abubakar ⁶ , Adeleke Abiodun ⁷ , Gbadebo Ibraheem ⁸ , John Onuminya ⁹ , Mohammed Salihu ^10,11

¹ National Orthopaedic Hospital Dala Kano, Spine Surgery, Kano, Nigeria,

² Nationwide Childrens Hospital, Clinical Research, Columbus, United States,

³ University of Alberta, Division of Orthopedic Surgery, Department of Surgery, Edmonton, Canada,

⁴ Usmanu Dan Fodiyo University Teaching Hospital, Orthopaedics, Sokoto, Nigeria,

⁵ Aminu Kano Teaching Hospital, Neurosurgery, Kano, Nigeria,

⁶ Bayero University Kano, Orthopaedics, Kano,

⁷ Obafemi Awolowo University Ife, Orthopaedics, Osun, Nigeria,

⁸ University of Ilorin Teaching Hospital, Department of Orthopaedics, Ilorin, Nigeria,

⁹ Irrhua Specialist Hospital, Irrhua, Orthopaedic, Edo, Nigeria,

¹⁰ National Orthopaedic Hospital Dala Kano, Orthopaedic, Kano, Nigeria,

¹¹ University of Abuja Teaching Hospital Gwagwalada, Department of Orthopaedics, Abuja, Nigeria

Introduction: Idiopathic Scoliosis (AIS) is a 3-dimensional deformity of the growing spine and accounts for about 85% of all cases of scoliosis. It is seen in 2-4% of adolescents. The Adolescent Idiopathic variety is the most common with the chance of curve progression 10-fold higher in females. Although largely a painless pathology, the accompanying deformity of the trunk is mostly a source of disturbance for the patients and their families. Early detection and treatment is advocated. Objective: To highlight the clinico-epidemiological profiles of patients with AIS and our early results of management of these patients. Materials and Methods: A hundred and two (102) patients with AIS had surgical correction between June 2016 and October 2023. Patient demographics, clinico-epidemiological data and deformity characteristics were recorded. All the patients were evaluated with plain radiographs, while those with Cobb’s magnitude of 90 and above had, in addition, a CT scan, an MRI scan and a pulmonary function test. All had posterior spinal fusion either as a single procedure or in combination with an anterior release/ Ghurki halopelvic traction. ASIA- IS and SRS-22r were used to measure outcomes. Post-operative plain radiograph immediately after surgery, at 3, 6 and 12 months were used to assess fusion. Average follow up period was 18 months. SPSS version 17 software was used to analyze the data. Results: The patients were aged 10 to 18 years, with a mean Cobb’s magnitude of 82°. Late presentation was common with an average presentation to intervention time of 10 months. Lenke 1AN was the most common. Forty three patients had thoracoplasty (anterior or posterior) in addition to the fusion (ATR greater than 25). GHT was applied in 20 patients while 32 had a staged correction. Two patients had neurologic impairment with a post-operative ASIA-IS of A and B. Eleven patients (about 11%) had shoulder imbalance postoperatively. Average blood loss was 750mL and average duration of surgery was 3hrs for curves less than 70°. Intra-operative neuro-monitoring was deployed in all cases. Conclusions: Results of AIS treatment is Nigeria is encouraging. The surgical correction is safe and the expertise is readily available. Public enlightenment, advocacy and education is necessary to create awareness about AIS and available treatment options.

Keywords: Idiopathic scoliosis, AIS, SRS-22r, Cobb’s angle, thoracoplasty, Halopelvic traction.

ID: 984

RF283: Is it necessary to extend fusion to L4 when correcting pediatric L5–S1 spondylolisthesis?

Ziming Yao ¹ , Jiahao Jiao ¹ , Dong Guo ¹

¹ Beijing Children’s Hospital, Department of Orthopaedics, Beijing, China

Introduction: Although PLIF is popular for pediatric lumbosacral spondylolisthesis, the optimal levels for fusion remains controversial. The objective of this study was to investigate whether extending fusion to L4 is imperative in the surgical treatment of pediatric L5-S1 spondylolisthesis. Material and Methods: 68 pediatric patients with dysplastic L5–S1 spondylolisthesis who underwent PLIF were categorized into two groups based on the upper instrumented vertebra (group L4 and group L5). Radiographic parameters including slip percentage (SP), lumbar lordosis (LL), sagittal vertical axis (SVA), pelvic incidence (PI), Spinal Deformity Study Group dysplastic lumbosacral angle (SDSG-LSA), pelvic tilt (PT), Dubousset’s lumbosacral angle (Dub-LSA), sacral slope (SS), and severity index (SI) were measured. Surgery-related data and complication data were also collected. The incidence rates of complications were compared, including those of neurological deficit, adjacent-segment instability (ASI), and other complications. ASI was defined as progression of slippage > 3 mm or posterior opening > 5° in the adjacent segment. Clinical outcomes were assessed with the numeric rating scale (NRS) and the Oswestry Disability Index (ODI) scores. The follow-up period for all patients lasted a minimum of 2 years. Results: Group L4 consisted of 15 patients and group L5 comprised 53 patients. The patients included in both groups had comparable baseline demographic characteristics and radiographic parameters. Postopera- tive SP and SDSG-LSA were significantly lower in group L5 (p < 0.05). No other postoperative radiographic differences were observed between groups. One patient in group L4 and 3 patients in group L5 experienced transient neurological deficits (p > 0.05). There were 13 cases of ASI in group L5 compared with none in group L4 (24.5% vs 0%, p > 0.05). Of the 13 patients with ASI, 4 underwent revision surgery due to L4–5 level instability and clinical symptoms. The remaining individuals exhibited no symptoms, and regular annual follow-up assessments are being conducted for all patients. The NRS and ODI scores at final follow-up did not exhibit any significant differences between the two groups. Conclusion: Fusion to L5 could achieve comparable satisfactory results to fixation to L4, albeit with increased likelihood of ASI. Extension of fusion to L4 may not be necessary for most patients with pediatric L5-S1 spondylolisthesis.

ID: 345

RF284: Active apex correction (APC) technique in early onset scoliosis. A report of 17 cases

Mutaleeb Shobode ¹ , Oladapo Ekundayo ² , Gbadebo Ibraheem ³ , Lukman Ajiboye ⁴ , Bolarinwa Akinola ⁵ , Omolola Fagbohun ⁶ , Adekunle Adebanjo ⁷ , John Onuminya ⁸ , Mohammed Salihu ⁹

¹ Nationwide Children's Hospital, Department of Orthopaedics, Clinical Research, Columbus, Ohio, United States,

² University of Alberta, Division of Orthopaedics, Edmonton, Canada,

³ University of Ilorin Teaching Hospital, Department of Orthopaedics, Kwara, Nigeria,

⁴ Usmanu Dan Fodiyo University Sokoto, Department of Surgery, Sokoto, Nigeria,

⁵ Osteon Clinic, Orthopaedics, Lagos, Nigeria,

⁶ Lagos State University Teaching Hospital, Department of Anaesthesia, Lagos, Nigeria,

⁷ Olabisi Onabanjo University Teaching Hospital Sagamu, Department of Surgery, Ogun, Nigeria,

⁸ Irrhua Specialist Hospital, Department of Orthopaedics, Edo, Nigeria,

⁹ University of Abuja Teaching Hospital Gwagwalada, Deaprtment of Orthopaedics, Abuja, Nigeria

Introduction: The Scoliosis Research Society defines Early Onset Scoliosis (EOS) as all spinal deformities seen in children before the age of 10. The main aim of treatment in EOS is to achieve a flexible spine while buying time for optimal thoracic volume and lung development. The Active apex Correction technique is a non-fusion, growth friendly modification of the SHILLA approach that aims to modulate growth at the apex of the deformity. It is particularly useful in resource poor environments like Nigeria as it obviates the need for multiple surgeries to lengthen the concavity. With the increasing interest in complex spine deformity care in Nigeria, there is the need to share our experience with the adoption of this novel technique in EOS care. Objective: To highlight the pathology and provide a preliminary report on the use of the APC technique as a non-fusion treatment option. Materials and Methods: Of the 35 patients that presented with EOS between 2022 and 2023, 21 had surgical correction using the APC technique. Patient demographics, clinico-epidemiological data and deformity characteristics were recorded. All the patients were evaluated with plain radiographs, CT scan, an MRI scan and a pulmonary function test. All are thoracic curves. ASIA- IS and SRS-22r were used to measure outcomes. Post-operative quarterly plain radiograph was used for monitoring the curves. Results: The 21 patients were aged 4 to 9 years. There were 7 males and 14 females with a mean Cobb’s magnitude of 88°. Nine patients with a bending Cobb’s of 90 and above had the Ghurki Halopelvic traction for 4 weeks prior to the non-fusion surgery. One patient had proximal foundation failure that was revised. There has been no worsening of the curves in any of the patients with significant improvement in coronal balance and curve magnitude. Average blood loss was 350mLs and average duration of surgery was 3hrs. The average follow up period was one 13 months. All had intra-operative neuro-monitoring. Conclusions: Early results of the use of the APC technique in the treatment of EOS are encouraging. The surgical technique is safe with minimal soft tissue dissection in most.

Keywords: Early onset scoliosis, APC technique, SRS-22r, Cobb’s angle

RF17: SPINAL ONCOLOGY 2

ID: 2738

RF285: Time is function: early surgery correlates to improved recovery for patients with intramedullary tumors

Leon Cleres Penido Pinheiro ¹ , Rodrigo Kei Kuromoto ¹ , Walterney Amancio Filho ¹ , Matheus Yamaki ¹ , Marlon Cesar Melo de Souza Filho ¹ , Rodrigo Almeida Cunha ¹ , Gustavo Lordelo ¹ , Andrei Joaquim ¹ , Eloy Rusafa Neto ¹ , Osmar Jose Santos de Moraes ¹ , Roger Schimidt Brock ¹

¹ Sao Paulo University, Sao Paulo, Brazil

Background: Intramedullary tumors are lesions that develop inside the spinal cord. These conditions are challenging to treat, and recovery can be demanding for patients. This study aimed to understand the recovery of patients with intramedullary tumors as a function of the time elapsed before surgical intervention. Methods: A retrospective analysis was conducted on patients with intramedullary spinal tumors treated at a tertiary hospital in São Paulo, Brazil, from 2017 to 2024. The values of the McCormick Scale (MCS) and modified Rankin Scale (mRS) were obtained before surgery and 12 months after surgery. The variation coefficient was calculated by subtracting the preoperative value from the 12-month postoperative value. The correlation between the time from clinical complaint to surgery (TCS) and the variation coefficient was analyzed using Spearman’s Rank Correlation. Results: A total of 41 patients underwent surgery for intramedullary tumors. The average time from clinical complaint to surgery was 12.1 months. The correlation coefficient between the McCormick Scale variation coefficient and TCS was 0.82 (S = 522.15, p < 0.001). The correlation coefficient between mRS variation and TCS was 0.70 (S = 852.81, p < 0.001). Conclusion: There is a significant statistical association between the 1-year postoperative status and the time elapsed before receiving appropriate treatment. These results are relevant for prioritizing surgery for patients suffering from intramedullary tumors.

ID: 524

RF286: Long-term neurological outcomes following surgical treatment of spinal schwannomas, a population-based cohort study

Aman Singh ¹ , Victor Gabriel El-Hajj ¹ , Erik Edström ¹ , Adrian Elmi Terander ¹

¹ Karolinska Institutet, Stockholm, Sweden

Introduction: Spinal schwannomas are the second most common primary intradural spinal tumors. Despite being mostly benign, they may cause spinal cord compression and subsequently acute or chronic neurological dysfunction. The primary treatment is surgical resection. The aim of this study was to identify pre- and postoperative predictors of favorable outcomes after surgical treatment for spinal schwannoma. Material and Methods: All adult patients surgically treated for a spinal schwannoma between 2006 and 2020 were eligible for inclusion. Medical records and imaging data were retrospectively reviewed. The primary outcome measures were neurological improvement according to the modified McCormick scale (mMC) and changes in motor deficit, sensory deficit, gait disturbance, bladder dysfunction and pain at long-term follow-up. Results: In total, 180 patients with a median follow-up time of 4.4 years were included. Pain was the most common presenting symptom (87%). The median time between symptom presentation and surgery was 12 months, while the median time between diagnosis (first MRI) and surgery was 3 months. Gross total resection (GTR) was achieved in 150 (83%) and the nerve root could be preserved in 133 (74%) patients. A postoperative complication occurred in 10 (5.6%). Surgery was associated with significant improvements in motor deficit, sensory deficit, gait disturbance, bladder dysfunction and pain (p < 0.001). Of these symptoms, bladder dysfunction was the one most often improved with complete symptom resolution in all cases. However, no other predictors of improvement could be identified. There were 3 cases of recurrence after GTR and 9 cases of regrowth after partial resection. A reoperation was performed in 6 (3.3%) cases. GTR was associated with a significant improvement in neurological status at long term follow-up and increased the chance of progression-free survival. Conclusion: In this population- based cohort study surgery was safe with few complications and associated with significant improvement in neurological status at the long-term follow-up for most patients. However, no predictive factors for postoperative improvement, for those with a preoperative neurological deficit could be identified.

ID: 320

RF287: Minimally invasive approches for lumbosacral plexus Schwannomas

Federico Landriel ¹ , Fernando Padilla Lichtenberger ¹ , Alfredo Guiroy ² , Manuel Soto ³ , Camilo Molina ⁴ , Santiago Hem ¹

¹ Hospital Italiano de Buenos Aires, Neurosurgery, Buenos Aires, Argentina, ² Clinica de Cuyo, Neurosurgery, Mendoza, Argentina, ³ Spine Clinic, The American-British Cowdray Medical Center, Neurosurgery, Mexico City, Mexico, ⁴ Spine Unit, Washington University School of Medicine, Neurosurgery, Saint Louis, United States

Introduction: Lumbosacral plexus schwannomas (LSPSs) are benign, slow-growing tumors that arise from the myelin sheath of the lumbar or sacral plexus nerves. Surgery is the treatment of choice for symptomatic LSPSs. Conventional retroperitoneal or transabdominal approaches provide wide exposure of the lesion but are often associated with complications in the abdominal wall, lumbar or sacral plexus, ureter, and intraperitoneal organs. Advances in technology and minimally invasive (MIS) techniques have provided alternative approaches with reliable efficacy compared with traditional open surgery. We describe 3 MIS approaches using tubular retractor systems according to the lesion level. Material and Methods: This was a multicenter, retrospective observational cohort study to evaluate the use of MIS tubular approaches for surgical resection of LSPSs. We included 23 lumbar and upper sacral plexus schwannomas. Clinical presentation, spinal level, surgical duration, degree of resection, days of hospitalization, pathological anatomy of the tumor, approach-related surgical difficulties, and outcomes were collected. Results: The posterior oblique approach was used in 43.5% of the cases, the transpsoas approach in 39.1%, and the transiliac in 17.4%. The mean operative time was 3.3 hours, and the mean hospitalization was 2.5 days. All tumors were WHO grade 1 schwannoma. Postoperative MRI confirms gross total resection in 91.3% of the patients. No patient requires instrumentation. The pros and cons of each approach were summarized. Conclusion: The MIS approaches adapted to the lumbar level may improve surgeons’ comfort allowing a safe resection of retroperitoneal LSPS.

ID: 1246

RF288: Intradural tumors treatment: is there any space to endoscopic spine surgery approach?

Juliano Dias ¹

¹ Hospital Universitário Risoleta Tolentino Neves, Belo Horizonte

Introduction: Spinal endoscopic surgery has demonstrated a revolutionary treatment in minimally invasive spine surgery. With the evolution of the technique, we have noticed more and more situations that the endoscopic surgery is indicated. The question that emerges is: “Is there any space of usage of Endoscopic Spinal Surgery to treat intradural tumors?” In this paper we will show that it is possible. We have collected data of series of three cases with intradural extramedullary tumors treated using spine endoscopic approach. Material and Methods: We have treated surgically three patients with intradural extramedullary tumors. The first case was a young female person with a huge thoracic meningioma and an important medullar compression. It was treated with full endoscopic procedure with a gross total resection of tumor and dura layer coagulation (Simpson II resection classification). We have had an excellent evolution and complete neurological functions recovery. The second case was another young woman with a lumbar epidermoid tumor, also treated with a full endoscopic procedure. It was possible a total resection tumor with a good evolution and a complete recovery deficit. And the third case was a male person with a lumbar Schwannoma, treated by a multiportal/triportal endoscopic access. It was able a total resection tumor with a good clinical evolution; and this triportal approach made it possible a dural layer closure using a bimanual maneuver. Results: The three patients have an excellent evolution after surgery, with a good image control and improving their clinical symptoms. Most frightening situations was the fear of intracranial hypertension after dural opening and manipulation. It was handled by using just the gravity in saline solution inflow with the lowest position saline site as possible; as well as the intraventricular neurosurgeons uses in their intraventricular tumors’ resections. Another challenging situation was the dural closure. In two first cases, treated by full endoscopic surgery, it was not possible to close the dura mater layer, and we knew it. So, we programed a non-hermetic dural closure, using an absorbable hemostat and fibrin glue. In the third case, it was possible to perform a bimanual dural manipulation and suture with the optic/endoscope fixed in the third portal. The landmarks portals entries were calculated using de “physics sines law” to triangulate the instruments in a proper target site. Conclusion: We were able to conclude that it is possible and feasible to explore the “intradural space” using the multiportals endoscopic surgery to resect specific tumors and others intradural lesions. And, possibly, it could be the first step to incorporate portable robots in use of intradural and spinal manipulations. But it is important to mention that the experience of the surgeon is critical to have good outcomes and, certainly more studies must be done to corroborate this technique and suggested approach.

ID: 1421

RF289: Vertebral reconstruction with customized 3D printed prosthesis after spondylectomy with a 5-year follow-up

Feng Li ¹ , Hui Liao ¹ , Jianfeng Guo ¹ , Wei Wu ¹

¹ Tongji Hospital Attached to Tongji Medical College Huazhong University of Science and Technology (HUST), Department of Orthopaedic Surgery, Wuhan, China

Introduction: Traditionally, surgical reconstruction after spondylectomy is performed with titanium cages, bone grafts and other methods, which has a low strength and high rate of subsidence in long term. 3D printing prosthesis was attributed to the customization of the vertebral defect and complex internal mesh geometries, increasingly accepted by orthopedics. This study aimed to evaluate the outcomes of vertebral reconstruction with patient-specific 3D printing prosthesis after tumor resection. A significant improvement of The Short-From-36 Health Survey (SF-36), The Musculoskeletal Tumor Society (MSTS) and Visual Analogue Scale (VAS) scores of all patients used 3D printing prosthesis have been observed. Material and Methods: The study enrolled 23 patients performed with spinal tumor resection and reconstructed by using patient-specific 3D printing Ti6Al4V implant from 2017 to 2024 in our department. Total operation time, implant placement time, blood loss and complications were recorded. SF-36, MSTS, VAS scores and Frankel grading were used to evaluate the clinical outcomes. X-ray, CT and MRI scanning were performed to evaluate the situation of bony fusion, collapse of spinal endplate and long-term results of spinal tumor resection. Results: Data of 23 patients were collected, the average follow-up duration was 51.5 ± 9.8 months. Female/male = 11/12; the mean age was 43.3 ± 6.5 years; These cases covered 8 cases thoracic tumor, 8 cases lumbar tumor and 7 cases sacral tumor. Including 2 cases schwannoma, 8 cases giant cell tumor, 5 cases osteoblastoma, 2cases hemangioma and 6 cases chordoma were diagnosed by pathological section. We demonstrated that reconstruction by using patient-specific 3D printing prosthesis after tumor resection revealed a decline of operation time and blood loss. 3D printing prosthesis mimic the morphology of adjacent vertebral endplates, as it was found to contribute immediate primary stability with instantaneous device ‘press-fit’ and self-location to correct position, the surgeon could place and fix the implant easily. Resulting in a significant reduction in implant placement time for the implant (< 3 min). Compared with pre-operation, a significant improvement of SF-36 (69 ± 9.85, p = 0.015), MSTS (22.5 ± 1.35, p = 0.014), VAS (2 ± 0.52, p = 0.012) scores and Frankel grading were observed. X-ray images demonstrated abundant new bone formation in the scaffold around three months after the operation, combined with a further CT scanning and MRI evaluation, we confirmed the that these implants had a good biological ability. Meanmore, no collapse of endplate was occurred. Conclusion: 3D printing implant exhibits a good matching rate with the morphology of adjacent vertebral endplates, excellent biological ability of bony fusion and a low ratio of collapse of endplate. The quality of life has been significantly improved.

ID: 2713

RF290: Outcomes after total en bloc spondylectomy at a mean follow-up of 11 years

Wai Kiu Thomas Liu ¹ , Kenny Yat Hong Kwan ² , Yat Wa Wong ¹

¹ Queen Mary Hospital, Department of Orthopaedics and Traumatology, Pokfulam, Hong Kong,

² University of Hong Kong, Department of Orthopaedics and Traumatology, Hong Kong, Hong Kong

Introduction: Total en bloc spondylectomy (TES) of spinal tumours results in huge vertebral defect. Despite reconstruction and fusion, there is potential concern for long-term mechanical stability. Material and Methods: Twenty-three patients (mean age: 40.0 ± 15.3 years) underwent TES for either primary spinal tumours or solitary metastasis and reconstruction with instrumented posterior spinal fusion and anterior fusion with titanium mesh cage in our institution from November 2001 to April 2022. The mean follow-up was 11.5 ± 4.9 years. Primary diagnoses include giant cell tumours (13), primary sarcomas (3), haemangiopericytomas (2), solitary metastases (2), aneurysmal bone cyst (1), haemangioma (1) and chordoma (1). The locations of the tumours were either in lumbar (10) or thoracic (13) spine. Fifteen patients had one vertebral level resected, others were two- (2), three- (4), four- (1), or five-level (1). Ten patients had fixation with both allogenous and autogenous bone grafts, five had autogenous bone graft only and eight had allogenous bone graft only. The mean duration of operation was 751.7 ± 212.6 minutes and the mean intraoperative blood loss was 2864.3 ± 2124.8 ml. The mean length of resected tumour was 51.6 ± 23.3 mm. Cage subsidence at post-operative 1-month and oblique placement of cage were noted in seven and eight patients, respectively. Investigated outcomes were instrumentation failure, revision and post-operative complications. Results: Twelve patients (52.2%) required revision surgery. Instrumentation failure occurred in eight patients (34.8%) and all of them required revision surgery, making it the most common indication for revision. All failures presented sudden back pain and rods breakage on x-ray. The mean time to instrumentation failure was 7.6 years (SD = 3.9 years). Instrumentation failure with rod fracture was associated with long operation time (p = 0.031), more blood loss (p = 0.022) and longer length of resected tumour (p = 0.035). No significant association was identified between the investigated outcomes and the parameters, including sex, pathology, pre-operative neurology, location of tumour, level of vertebra resected, type of bone graft used, surgical approach, tumour margin, radiotherapy, chemotherapy, current disease status, distant metastasis, local recurrence, cage subsidence, oblique cage placement, bony fusion, and number of rods used. Radiological evidence of bony fusion could be seen in both groups (62.5% in failure group vs. 86.7% in no failure group), and there was no significant difference between the two groups (p = 0.181). Local recurrence of the pathology occurred in three patients (13.0%). According to Kaplan Meier analysis, the overall revision-free survivals were 67.0%, 48.8% and 36.6% at post-operative 5-, 10- and 15-year, respectively. The 5-, 10-, 15-year instrumentation failure-free survivals were 85.2%, 65.7%, and 56.3%, respectively. 91.3% and 84.3% of the patients would be free from local recurrence at post-operative 5- and 10-year, respectively. Conclusion: Although local recurrence after TES was uncommon, revision surgery was quite common following TES. Instrumentation failure is not an uncommon late complication requiring revision following TES. Longer lengths of resection and longer complicated operations are at risk of future instrumentation failure. Even fusion has taken place, the strength of the fusion block may be suboptimal, therefore, bony union does not guarantee long-term success of the construct.

ID: 1880

RF291: Postoperative patient-controlled epidural analgesia in spine metastases

Esteban Ramirez Ferrer ¹ , Keyuri Popat ² , Romulo Andrade de Almeida ¹ , Christopher Alvarez-Breckenridge ¹ , Rob North ¹ , Laurence Rhines ¹ , Claudio Tatsui ¹

¹ MD Anderson Cancer Center, Neurosurgery, Houston, United States,

² MD Anderson Cancer Center, Anesthesiology and Perioperative Medicine, Houston, United States

Introduction: Spinal metastases occur in 20-30% of cancer patients, often signaling uncontrolled disease. These metastases are associated with reduced Quality of Life due to refractory pain, mobility limitations, and neurologic deficits. Additionally, postoperative pain control in complex spinal oncological surgery has been a challenge. Different strategies addressing refractory pain have been described, including erector muscle blockage, postoperative Patient-Controlled Intravenous Analgesia (PCIVA), and epidural analgesia, without a clear superiority of one. Furthermore, the evidence of Patient-Controlled Epidural Analgesia (PCEA) is scarce and null in the context of spinal metastasis surgery. We decided to assess postoperative pain control in patients with spinal surgery for metastatic disease treated with epidural analgesia through patient-controlled catheter infusion (PCEA) and compare it to PCIVA. Material and Methods: We did a retrospective review of our cohort of patients from January 1^st, 2019, to August 31^st, 2023, with spinal metastases who underwent spinal surgery and in whom an epidural catheter for postoperative analgesia infusion was implanted. We excluded the pediatric population, patients with previous spinal surgery, percutaneous procedures, other analgesic procedures performed during the surgery (e.g., erector spinal muscle blockage), and recent (< 6 months previously) use of pain pumps. To obtain a comparative group, we matched this group with a cohort treated with PCIVA for demographic data, Frankel status, opioid use, and catheter duration. The match's success between the two groups was assessed by obtaining p-values using an independent-sample t-test and chi-square. P values below 0.05 were considered statistically significant. The primary outcome was the pain Visual Analogue Scale (VAS) difference between the preoperative and postoperative periods. The secondary outcomes were the postoperative pain VAS scores, the postoperative rehabilitation scores measured through AMPAC, and the Gait FMI score. Results: The most common primary oncologic diagnosis was renal clear cell carcinoma in both groups. No statistical differences were documented regarding primary oncologic diagnosis (p = 1), time in surgery (p = 0.45), vertebrectomies (p = 0.78), number of transpedicular screws (p = 0.24), carbon-fiber hardware cases (p = 0.81), preoperative embolization cases (p = 0.75) or preoperative radiotherapy (p = 0.6). Regarding the primary outcome, there was a statistically significant lower postoperative pain VAS in the PCEA group from the second day to the fourth (p = 0.04). Still, no differences were documented before or after this period. However, there was a higher difference between preoperative and discharge from hospital VAS in PCEA (p = 0.03). Also, there were higher rehabilitation scores in PCEA at discharge from the hospital (p = 0.03). Interestingly, the PCEA had a lower Morphine Equivalent Dose (MED), but no statistically significant difference was found. Conclusion: PCEA offers a safe alternative for postoperative care in patients undergoing vertebrectomies and posterior instrumentation for spinal metastasis, with higher rehabilitation rates at discharge compared to PCIVA. However, it does not provide superior immediate postoperative pain control. Finally, although the MED was less in the PCEA group, controlled trials are required to assess this finding, which was not statistically significant in this study.

ID: 487

RF292: Development and internal validation of Unable to Surgery Predictive Score for Spinal metastasis Score (USPS) for spinal metastasis surgery

Warunyu Limmaneevichitr ¹ , Nath Adulkasem ¹ , Borriwat Santipas ¹ , Sirichai Wilartratsami ¹ , Pinprapha Boonhyad ² , Panya Luksanapruksa ¹

¹ Faculty of Medicine Siriraj Hospital, Mahidol University, Department of Orthopedic Surgery, Bangkok, Thailand,

² Faculty of Medicine Siriraj Hospital, Mahidol University, Division of Research, Department of Orthopedic Surgery, Bangkok, Thailand

Background: Scoring systems for metastatic spine disease predominantly concentrate on post-operative mortality and morbidity. Nevertheless, accurately predicting perioperative mortality alone may be the primary factor to consider when contemplating surgical intervention. Our objective was to create and assess a novel tool, known as Unable to Surgery Predictive Score for Spinal metastasis Score (USPS), which aims to predicated on the patient’s ability to tolerate spinal metastasis surgery. Methods: This retrospective cohort study was included all spinal metastasis patients who underwent surgical treatment from 2008 to 2023. We considered various potential predictors, such as clinical performance status and laboratory parameters. Subsequently, a predictive score was developed using multivariable logistic regression modeling with these potential predictors. Results: A total of 467 patients were included. Among the inpatient population, 3.42% (N = 16) of patients experienced postoperative mortality. The severe complications contributing to mortality included pulmonary embolism in 1.71% (N = 8) of cases and myocardial infarction in 2.78% (N = 13) of cases. The factors independently associated with these outcomes, which formed the predictive model, were the presence of anemia, (male with Hb < 12 g/dl, female with Hb < 13 g/dl), ASIA score below grade C, American Society of Anesthesiologist (ASA) grade more than grade 2, albumin deficiency, and end-stage renal disease (GFR < 15 mL/min/1.73 m2). The defining the risk categories in the predictive model resulted in Safe surgery (score 0-3), Potential inability to tolerate surgery (score 4-7) and Avoid surgery (score ≥ 8). The discriminative ability of the final model was found to be good, with an AuROC of 0.72 (95% CI 0.65 to 0.78). Conclusion: The USPS is a tool that predicts the ability of a patient to tolerate surgery for spinal metastasis. Its specificity for post operative mortality and morbidity, as well as its simplicity, make it a predictor tool for surgeons when making clinical decisions for patients with metastatic spine disease.

Level of Evidence: Level II

Keywords: Spinal metastatic surgery, Post operative mortality and morbidity, Predictor tool

ID: 1772

RF293: Health-related Quality of Life in patients treated with enbloc resection for primary tumor of the spine

Luigi Emanuele Noli ^1,2 , Chiara Alcherigi ² , Cristiana Griffoni ² , Eleonora Pesce ² , Simona Rosa ³ , Gisberto Evangelisti ² , valerio pipola ² , Paolo Francesco Davassi ² , Annalisa Monetta ² , Giovanni Barbanti Bròdano ² , Silvia Terzi ² , riccardo ghermandi ² , Giuseppe Tedesco ² , Marco Girolami ² , Stefano Bandiera ² , Alessandro Gasbarrini ²

¹ ISNB Istituto delle Scienze Neurologiche di Bologna, Bologna, Italy,

² IRCCS Istituto Ortopedico Rizzoli, Department of Spine Surgery, Bologna, Italy,

³ Alma Mater Studiorum University of Bologna, Department of Biomedical and Neuromotor Sciences, Bologna, Italy

Introduction: En bloc resection in the spine is a surgical procedure designed to completely remove a tumor in one piece, with wide margins preserved, in order to reduce the risk of local recurrences. This demanding procedure has been shown to guarantee better local control and survival rates and, besides a relatively high morbidity. The aim of this study is to evaluate the functional outcomes and the health-related quality of life (HRQOL) in patients undergoing en bloc resection of spinal tumors. Material and Methods: 327 patients underwent en bloc resection between 1980 and 2021 and 38 came out to be eligible for this analysis. Eligibility criteria includes at least one follow-up visit within a two-year period from surgery and Patient Reported Outcomes evaluation collected prospectively at baseline and at least one follow up in the range 4-24 months. The outcome variables (EQ5D Numeric Scale and Index, SF36 scores and NRS score) were analyzed with multilevel linear mixed-effects regression. Baseline (age, gender, localization, histotype, number of levels of resection, previous surgery) and time-dependent covariates (adverse events, spinal cord damage) were included. Results: Beside a slight improvement of all the scores, no significant differences were found between baseline and follow up times for EQ-5D-3L Numeric Scale and Index and for SF-36 Standardized Physical component. SF-36 Standardized Mental component appeared to be significantly better at 12-month FU compared to baseline. Ultimately, age over 50 years old and the occurrence of adverse events emerged to be as the two main factors determining worsening in several HRQOL scores. Pain came out to be significantly reduce at 24-month compared to baseline. Conclusion: En bloc resection guarantees better survival outcomes and, despite its radicality, our preliminary results suggest that patients experience a slight to moderate improvement postoperatively compared to their preoperative perceived health status.

ID: 629

RF294: Treatment strategies for intermediate Spinal Instability Neoplastic Score (SINS 7-12) patients: a systematic review

Benard Okai ¹ , Esteban Quiceno Restrepo ² , Mohamed Soliman ² , Hendrick Francois ¹ , Isabelle Stockman ¹ , Shashwat Shah ¹ , Jacob Greisman ² , Asham Khan ² , Joseph St. Onge ¹ , Deanna Chan ¹ , John Pollina ² , Jeffrey Mullin ²

¹ Jacobs School of Medicine And Biomedical Sciences, Neurosurgery, Buffalo, United States,

² University at Buffalo Neurosurgery, Neurosurgery, Buffalo, United States

Introduction: Various prognostic scores such as the Spinal Instability Neoplastic Score (SINS) have been developed to assess impending spinal instability in patients with spine metastasis. Patients with intermediate SINS scores (7-12) are categorized as “potentially unstable” and require tailored treatment. This systematic review evaluates diverse treatment options for this patient group. The objective of our study was to identify the management patterns for patients with intermediate SINS scores. Material and Methods: We conducted a systematic search of English-language literature from PubMed, Embase and Cochrane databases between 2010 to 2023. Inclusion criteria encompassed studies involving metastatic disease, SINS scores between 7-12, and treatment information. Data was extracted using the PRISMA guidelines. Results: Our search identified 1201 articles, with 9 meeting the inclusion criteria. Among the diverse findings, surgical interventions, external beam radiation therapy (EBRT) combined with surgery (S+E) and cement augmentation with EBRT (K+E), were associated with better survival and ambulatory ability, although they raised concerns regarding revision rates. Vertebral instrumentation was more common in cases with higher SINS scores but showed no significant neurological outcome advantage, with increased complications. Vertebrectomy demonstrated improved survival in patients with indeterminate SINS, but blood loss was higher in this group. SINS scores predicted the risk of vertebral compression fractures (VCF) post-stereotactic radiosurgery (SSRS), with the majority of VCFs occurring within the first four months. A correlation between SINS scores and short-term mortality was evident, emphasizing the importance of the assessment in risk stratification. Conclusion: The comprehensive systematic review underscores the multifaceted considerations in managing spinal metastatic disease, highlighting the relevance of SINS scores in guiding treatment decisions. Clinicians should employ a multidisciplinary approach, carefully balancing stability, neurological outcomes, and potential complications. These findings contribute significantly to the evolving body of knowledge and the enhancement of clinical practice for patients with spinal metastatic disease, offering a pathway to improved decision-making and patient outcomes.

ID: 1784

RF295: Hadron-therapy effectiveness in the treatment of mobile spine chordomas after intralesional excision and in the mangement of local recurrencies. A retrospective observational study

Valerio Pipola ¹ , Stefano Bandiera ¹ , Riccardo Ghermandi ¹ , Silvia Terzi ¹ , Giovanni Barbanti Bròdano ¹ , Giuseppe Tedesco ¹ , Gisberto Evangelisti ¹ , Marco Girolami ¹ , Stefano Pasini ¹ , Luigi Falzetti ¹ , Emanuela Asunis ¹ , Giovanni Tosini ¹ , Marco Cianchetti ² , Maria Rosaria Fiore ³ , Alessandro Gasbarrini ^{1 4}

¹ IRCCS Istituto Ortopedico Rizzoli, Department of Spine Surgery, Bologna, Italy,

² Azienda Provinciale per i Servizi Sanitari, Prton Therapy Unit, Trento, Italy,

³ CNAO Centro Nazionale di Adroterapia Oncologica, Pavia, Italy,

⁴ University of Bologna, Department of Biomedical and Neuromotor Sciences, Bologna, Italy

Introduction: To evaluate the outcomes in patients diagnosed with Chordoma or local recurrence of Chordoma of the mobile spine, after surgical treatment with intralesional excision and CRF-PEEK instrumentation, followed by hadron-therapy. Material and Methods: Data were retrospectively collected between January 2015 and April 2020. Inclusion criteria were:

• patients aged 11 or over;

• patients diagnosed with Chordoma undergoing surgical treatment with inappropriate margins according to the Enneking classification;

• patients diagnosed with Chordoma of the mobile spine, whose localization and/or local extension was not suitable for en bloc resection surgery with marginal or wide margin according to the Enneking classification;

• patients diagnosed with local recurrence after en bloc resection. Results: Twenty-one patients (14 M and 7 F) meeting the inclusion criteria were included in the study. The mean age was 61.4 years (range 12 - 81). The localizations of the lesions were: 3 (14%) in the cervical spine, 5 (24%) in the thoracic spine and 13 (62%) in the lumbar spine. Seven patients (33%) presented local recurrence after marginal resection. These patients underwent intralesional excision of the recurrence and fixation with CRF-PEEK instrumentation. Thirteen patients (62%) had undergone a previous intralesional surgery considered inappropriate, according to Enneking criteria: 2 underwent en bloc resection, 4 underwent gross total excision, 5 underwent extracapsular intralesional excision of the lesion and 2 had an intracapsular intralesional excision. All patients underwent adjuvant hadron-therapy: carbon ion therapy (8 patients) and proton therapy (13 patients). Four patients experienced a local recurrence with a mean interval of 21 months (range 16- 27). One is died of disease (DOD) and 3 are alive with disease (AWD). The remaining 17 patients have no evidence of disease (NED) at follow-up. The local disease control rate was 71.8% at 24 months and 61.5% at 36 months. Conclusion: Hadron-therapy is able to obtain a high local control rate in the treatment of chordoma recurrences after surgery with inappropriate resection margins. A prospective observational study is ongoing to confirm the hadron-therapy effectiveness and to evaluate the correlation between the local recurrence and the presence of residual disease after surgery.

ID: 2693

RF296: 3D virtual models vs. 2D imaging: improving preoperative planning for complex spinal tumour resections - A retrospective controlled cohort study

Miki Shikanai ¹ , Aditya Swaminathan ¹ , Ilijana Sumonja Zisakis ² , Siu Li Boo ² , Melvin Grainger ² , Huma Haseeb ² , Thomas Land ² , Jonathan Shadwell ² , Hussein Shoukry ² , Wai Cheong Soon ² , Sophie Walters ² , Marcin Czyz ²

¹ College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom,

² University Hospitals Birmingham NHS Foundation Trust, Birmingham, United Kingdom

Introduction: Spinal tumours, which are rare yet debilitating, pose diagnostic and surgical challenges. In certain cases, en bloc resection (EBR) offers superior outcomes, but demands anatomical precision. Implementation of three-dimensional virtual models (3DVM) to the preoperative work-flow can aid procedural planning, enhancing understanding and confidence, and thus patient outcomes. This study evaluates the accuracy of 3DVM in depicting tumour-related anatomical distortion, and assesses the feasibility of implementing this technology to clinical practice as an education and communication tool. Material and Methods: This retrospective study at Queen Elizabeth Hospital Birmingham included 31 patients with spinal tumours who underwent EBR between 01/01/2019-01/02/2024, with no limits on histology, vertebral level, or surgical approach used. 3DVM were created by fusing routine CT and MRIs using commercial neuronavigation software. Time spent on each phase (image selection, tumour demarcation, and anatomical reconstruction) was recorded in every case. A novel scoring index, the Scale of Anatomical Distortion (SAD), was developed to quantify tumour invasion into surrounding neural, vascular, osseous, and soft tissue structures. This enabled quantitative comparison between the accuracy of 2D scans and 3DVM, relative to a benchmark score and to each other. Benchmark values were generated from evaluations by four neuroradiologists. Six spinal surgeons with varying levels of training validated the 2D scans and 3DVM. Surgeon perception of utilising 3DVM was surveyed through an 11-question Likert-scale survey. Statistical analyses performed included Spearman’s, Wilcoxon, Kruskal-Wallis, and Cohen’s Kappa for modality comparison. Results: The SAD index showed reliability and consistency, indicated by the strong correlation between surgeon 2D and benchmark scores (Spearman’s ρ = 0.75; p < 0.0001) and fair to moderate inter-rater agreement (Kappa’s κ = 0.47). Each 3D reconstruction took approximately 70 (±25) minutes. 3DVM depicted tumour anatomy accurately (ρ = 0.771; p < 0.0001; κ = 0.54), though bony distortion tended to be overestimated (p = 0.02), and vascular distortion was less accurately represented (κ = 0.19). Agreement between surgeon scores and benchmark values improved with the addition of 3DVM (κ increased from 0.47 to 0.54) compared to 2D scans alone, particularly among younger surgeons. Surgeons underestimated tumour volume with 2D scans (p = 0.0009), and fellows scored 3DVM faster than 2D images (p = 0.01). Learning curve analysis demonstrated improved usability of 3DVM over time (R² = 0.74). The questionnaire yielded positive results, with both junior and senior surgeons agreeing on the benefits to preoperative planning and education in most cases. Conclusion: 3DVM are easy to interpret, accurate, and improve EBR planning, concordant with existing literature. However, they do not enhance distortion visibility compared to 2D images. While the SAD index was simple to use, it requires refinement to minimise subjectivity. The feasibility of 3DVM implementation into clinical and educational settings was viewed positively. Future research should evaluate 3DVM predictive accuracy for surgical outcomes. Additionally, it should explore their integration into virtual or augmented reality to enhance training and precision.

ID: 2461

RF297: Spinal metastasis in patients with soft tissue sarcomas, a retrospective case series

Akbar Jaleel Zubairi ¹ , Muhammad Ahsan Sulaiman ¹ , Javeria Saeed ¹ , Fateh Ali Janjua ¹ , Bilal Raza Slote ¹ , Masood Umer ¹

¹ Aga Khan University Hospital, Karachi, Pakistan

Introduction: Soft tissue sarcomas (STS) are a group of rare and heterogeneous tumors that are uncommon. Patients suffering from soft tissue tumors are at risk of having metastasis to areas such as the lungs, liver, brain, and bone. Despite adequate resection there is a risk of recurrence at distant sites with the majority of the spread occurring through the blood. This study aimed to determine the associated risk factors associated with spinal metastases in soft-tissue tumors with this study. Material and Methods: We conducted a retrospective study, that included patients with a history of biopsy-proven soft tissue sarcoma and spinal metastasis, treated from January 2008-2019 December. All the patients’ data was collected from the Hospital-based Orthopedic Tumor Registry. Ethics review committee (ERC) exemption was taken for conducting this study. Results: Out of 17 cases of soft tissue sarcoma, 9 (52.9%) had metastasized to the spine. The most common presenting complaint was swelling and the mean duration of complaints at presentation was 7 months. The mean follow-up duration was 11.1 14.0 months. Soft tissues Ewings Sarcoma had the greatest number of cases which was 3. There was 1 case of Liposarcoma and 1 of High-grade malignant Peripheral Nerve Sheath Tumor and the rest of the cases were different from other single morphologies of tumor. The metastatic lesions were spread in different regions of the spine, 4 were located around the thoracic spine, 3 in region lumber, 1 in sacral and 1 cervical spine. Out of 9 patients, 4 patients died and the rest of the 5 patients (55.5%) were alive. Conclusion: Our study showed few numbers of patients with spinal metastasis, having a low survival rate and heterogeneous morphology of the disease along with multiple locations in the body.

ID: 1173

RF298: A descriptive analysis of spinal melanocytoma in current literature: review of clinical presentations, treatment regiments and histological parameters

Davide Marco Croci ¹ , Mehdi Rizk ² , Bryan Clampitt ³ , Sarah Moffitt ³

¹ University of South Florida, Neurosurgery and Brain Repair, Tampa, United States,

² University of South Florida, Morsani College of Medicine , TAMPA, United States,

³ University of South Florida, Morsani College of Medicine , Tampa, United States

Introduction: Melanocytomas are benign CNS neoplasms that are locally aggressive and can present within the spinal canal. Clinical manifestations generally lead to focal neurological deficits. Complete surgical resection is the recommended treatment and often provides the most favorable prognosis. Diagnosis of melanocytomas relies on immunohistochemical markers such as S-100, Melan-A, and HMB-45. Our review of current literature on intraspinal melanocytomas aims to describe the demographic variables, clinical manifestations and treatments, histological parameters, and outcomes of the disease. Methods: A literature search was conducted using the PubMed database from 1978 to 2024 for relevant English-language publications. The key search terms were (melanocytoma) AND ((spinal) OR (spine)). All retrieved publications underwent an initial screening process by the research team to remove any duplicate articles, as well as sources where access to the full publication was not possible. After this initial screening, our team identified relevant inclusion and exclusion criteria to further refine our dataset. Results: There was a total of 102 patients extracted from 80 included studies, with 56 males and 46 females. The average age of a patient in our analysis was 47.68, ranging from 14 to 79 years old. Most patients’ lesions were located either within the thoracic (n = 55, 53.9%) or cervical (n = 37, 36.3%) spine. Surgical outcomes were primarily split between subtotal (32.6%) and gross total (58.7%) resection. 26 (32.9%) patients reported tumor recurrence. Only 21 cases had specific mentions of the pursuit of radiotherapy, in which 40.9% of patients did. 62.7% of patients with reported post-operative symptomology had complete symptom resolution. Primary lesion grading was only described for 29 patients, with 7 (24.1%) described as “low” and 22 (75.9%) described as “intermediate.” A positive reaction to the S-100 stain was described in 75 out of 79 reported values (94.9%). Epithelial Membrane Antigen (EMA) stain positivity was described in 3 out of 57 patients (5.3%). HMB-45 positivity was described in 70 out of 71 patients. Discussion: Intraspinal melanocytomas are rare and have been minimally analyzed. Our analysis has shown the need for more thorough descriptions of cases of melanocytomas in future research to allow for the capability of a more precise review and analysis.

ID: 1579

RF299: Impact of the UK Spinal Sarcoma Surgical Forum on the treatment recommendations - an analytical review

Nikhil Mummaneni ¹ , Jeremy Reynolds ¹ , Melvin Grainger ² , Alistair Irwin ³ , Hanny Anwar ⁴ , Simon Hughes ⁵ , Thomas Land ² , Gerard Mawhinney ¹ , John Afolayan ⁴ , Marcin Czyz ²

¹ Oxford University Hospitals NHS Trust, Department of Spine Surgery, Oxford, United Kingdom,

² University Hospitals Birmingham NHS Trust, Department of Neurosurgery, Birmingham, United Kingdom,

³ The Newcastle Upon Tyne Hospitals NHS Trust, Newcastle, United Kingdom,

⁴ Royal National Orthopaedic Hospital NHS Trust, London, United Kingdom,

⁵ Royal Orthopaedic Hospital NHS Trust, Birmingham, United Kingdom

Introduction: There is approximately one spinal sarcoma specialist per 10 million people in the UK. With half of the UK's centers having a single specialist, isolated decision-making on a per-center basis is suboptimal, especially for a cancer that has one of the highest complication rates and worst outcomes. To address this need, all of the UK’s spinal sarcoma specialists have collaborated to create a virtual forum that allows for peer-to-peer support in decision-making. By allowing for a national review of complex spinal sarcoma patients, the forum aims to give specialists and patients clarity in treatment plans. Artificial intelligence-powered analysis of the forum recordings is a promising way to evaluate their impact. Materials and Methods: We analyzed 30 cases discussed during the UK Spinal Sarcoma Forum. Forum transcripts were generated using Microsoft Teams software and corrected manually. During the correction process, identifying patient information was removed from the transcripts. A researcher manually reviewed the forum recordings for information on each case discussed, such as diagnosis, spinal levels involved, and whether treatment recommendations were altered by forum deliberation. The forum transcripts were then uploaded to ChatGPT-4 for analysis of the same parameters. Results: Analysis comprised 30 cases with the median age of 30 years (IQR 33). Diagnoses included: aggressive haemangioma n = 1, anapaestic ependymoma n = 1, aneurysmal bone cyst n = 1, chondrosarcoma n = 6, chordoma n = 4, rhabdomyosarcoma n = 1, Ewing’s sarcoma n = 4, epithelioid sarcoma n = 1, malignant peripheral nerve sheath tumour n=3, osteoblastoma n = 2, osteosarcoma n = 2, giant cell tumour n = 4. The manual analysis revealed that the forum impacted treatment recommendations in 67% of the cases discussed. Meanwhile, ChatGPT-4 reported that the forum impacted care decisions only 33% of the time. Furthermore, the manual analysis and ChatGPT-4 analysis agreed on the patients in all cases, and the spinal levels involved 57% of the time. Interestingly, the transcripts generated by Microsoft Teams were 94.53% accurate compared to their manually corrected counterparts. Conclusion: Our study reveals that the UK’s Spinal Sarcoma Forum is a critical part of shaping care recommendations for complex cases. Based on these findings, national peer-to-peer support forums should be explored in the context of other fields of complex surgical oncology. We also demonstrate that ChatGPT-4 is not a viable tool for analyzing MDT efficacy. Though AI holds promise in this application, further development in its ability to analyze medical discussions is needed.

ID: 1583

RF300: Local control after adjuvant radiosurgery in metastatic spine disease treated with decompression and hardware stabilization: a comparative study between carbon fiber/PEEK and titanium implants

Romulo Augusto Andrade de Almeida ¹ , Francisco Call-Orellana ¹ , Esteban Ramirez Ferrer ¹ , Juan Zuluaga ¹ , Gil Kimchi ¹ , Christopher Alvarez-Breckenridge ¹ , Laurence Rhines ¹ , Rob North ¹ , Claudio Tatsui ¹

¹ The University of Texas MD Anderson Cancer Center, Department of Neurosurgery, Houston, United States

Introduction: The use of carbon fiber-reinforced polyetheretherketone (CFRP) spinal implants is gaining popularity in the management of spinal metastasis as they produce less imaging artifacts and have less interaction with radiation particles than traditional titanium hardware. These properties may enhance post-treatment surveillance and potentially translate into an improved outcome especially in patients undergoing spinal stereotactic radiosurgery (SSRS) where precise imaging is essential for accurate planning. In this study, we evaluated local control and hardware durability in patients with spine metastases treated with decompressive surgery and either CFRP or titanium hardware stabilization followed by SSRS. Materials and Methods: This double-arm, retrospective cohort study was approved by the local institutional review board. Patients who underwent decompressive surgery with posterior segmental instrumentation for metastatic spine disease were screened based on specific inclusion and exclusion criteria. Exclusion criteria: 1) cervical implants, 2) mixed-type hardware, 3) SSRS performed more than 60 days post-surgery, and 4) less than three months of MRI follow-up. Included patients had their electronic medical charts accessed for collection of demographics, clinical, pathological, surgical, radiation, and follow-up data. Only tumor progression occurring inside or at the margins of the irradiated field was considered. An alpha of 5% was used to determine significance. Results: A total of 82 patients, corresponding to 83 spinal segments (55 titanium and 28 CFRP) were evaluated. The two groups were statistically similar with respect to age, sex, KPS, number of affected vertebras, transitional segment, screw quantity, and construct length. The mean follow-up time was 20.7 months (range, 3.0-70.4 months). Fifteen local progressions were identified, all in the titanium group (p = 0.02). The cumulative incidence using competing risks analysis using death as a competing factor showed a statistically significant lower local progression in the CFRP group (p = 0.004). The mean time to progression was 9 months (range, 2-33 months), with local progression-free survival being significantly higher in the CFRP group (p = 0.005). Notably, a larger proportion of patients in the CFRP group received single fraction 24Gy SSRS compared to multi-fraction regimens of 27Gy or 30Gy. Single fraction 24Gy SSRS was significantly associated with local control (p = 0.009). Multivariate analyses confirmed that both CFRP hardware and single fraction SSRS were independently associated with better local control. Regarding hardware failure, the titanium cohort experienced four failures: two cage subsidence, one screw subsidence, and one screw breakage. The CFRP group had two cases of screw breakage and loosening. The difference in hardware failure rates between the groups was not statistically significant (p > 0.05). Conclusion: CFRP implants were associated with improved tumor control when compared to titanium counterparts. We hypothesize that superior results may be attributed to less artifacts in post-operative imaging facilitating planning leading to more patients receiving single fraction 24 Gy SSRS, which is linked to better local control. Nevertheless, the consistent significance of CFRP in multivariate analysis even after accounting for the radiation fractionation, suggests that improved local control with CFRP hardware can be achieved independently of the radiation scheme employed. No differences in hardware durability were identified.

ID: 1411

RF302: Early data from the OxMINT project a novel multidisciplinary service model for managing metastatic bone disease

Georgios Zilidis ¹ , Clare Jacobs ² , Gerard Mawhinney ³ , Jeremy Reynolds ³ , Yaron Berkowitz ⁴ , Emma Kenney-Herbert ² , Ather Siddiqi ⁵ , James Teh ⁴ , Basavaraj Chari ⁴ , Martin Gillies ⁶ , Tim Mccormick ⁷ , Ami Sabharwal ² , Stana Bojanic ⁸ , Hayley Jones ² , Alex Anderson ⁹ , Claire Worrall ⁹ , Niamh Louwman ⁹ , Harriet Dent ⁹ , Mariam Latif ⁷ , Tomasz Bajorek ¹⁰ , Victoria Bradley ⁹ , Nicolas Beresford-Cleary ¹

¹ Oxford University Hospitals, Oxford Spinal Surgery Unit, OxMINT, Oxford, United Kingdom,

² Oxford University Hospitals , Department of Clinical Oncology, Churchill Hospital, Oxford, United Kingdom,

³ Oxford University Hospitals , Spinal Surgery , Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom,

⁴ Oxford University Hospitals , Department of Musculoskeletal Radiology, Oxford, United Kingdom,

⁵ Oxford University Hospitals , Orthopaedic Oncology and Arthroplasty, Oxford, United Kingdom,

⁶ University of Oxford, Neurosurgery, Oxford, United Kingdom,

⁷ Oxford University Hospitals, Department of Anaesthesiology, Oxford, United Kingdom,

⁸ Oxford University Hospitals , Department of Neurosurgery, Oxford, United Kingdom,

⁹ Oxford University Hospitals , Department of Palliative Medicine, Oxford, United Kingdom,

¹⁰ Oxford University Hospitals , Department of Psychiatry, Oxford, United Kingdom

Introduction: Metastatic or secondary bone tumours are known to be associated with skeletal-related events, such as pathological fractures, spinal cord compression, or hypercalcemia. These deposits are often highly painful and cause significant functional impairment and harm to quality of life. Recent advances in cancer treatment have improved patient survival in almost all cancer types which amplifies the magnitude of the problems as more patients are living longer with greater volumes of symptomatic bony disease. We would estimate based on rising prevalence of cancer in the UK predicted to reach 3.5million in 2025, the number of patients living with bone metastases will reach epidemic proportions. While management pathways of the much rarer primary bone tumours is well established there has not until now there has not been a unified pathway for the review of secondary bone tumour patients in the UK to ensure equitable and appropriate management. In Oxford we have set up a comprehensive service to manage symptomatic bone metastases and present our case series thus far. Materials and Methods: We will present the collated data from attempting to build a burgeoning evidence base for the best personalised treatments for patients including combination treatments across the gamut of surgical, interventional and radiological procedures with a focus on complimentary interventions and the order they offer greatest impact. Results: We will present data from all cases discussed in this novel service since November 2023 with descriptive statistics including objective measures of improvement in pain control following intervention. At the point of submission, we have collected activity and outcome data on the first 108 unique patients discussed in 125 documented MDT discussions. Patients had a spread of haemato-oncological diagnoses, with an average age at diagnosis of 66 years and an even split of men and women. Patients discussed were on an average oral morphine equivalent dose of 85 mg and 56% of referrals were from the Palliative Medicine service. Over 70% of referrals were for outpatients and the majority of those who were hospital or hospice inpatients had been admitted due to uncontrolled symptoms. The average time from referral to discussion was 2 days and for referral to procedure was 21 days. In 86 cases intervention was suggested (24 surgical, 28 interventional radiology, 5 anaesthetic and 29 external beam radiotherapy). Conclusion: Integrated and collaborative models for working are essential for the successful management of metastatic bone disease and this provides an example of service design and set up with initial data from patients referred in over a 9 month period. Our long-term goal is to for this service to offer a single point of contact that will access recommend plan and offer multidisciplinary treatments for patients with metastatic bone disease in a timely and efficient manner that will improve their long-term outcomes and their quality of life.

RF18: SPINE TRAUMA

ID: 1908

RF303: Decisional regret in orthopaedic surgery: a systematic review of assessment tools

Michael Jeffko ^1,2 , Laura Reynolds ^1,2 , Maxey Cherel ^1,2 , Aiyush Bansal ² , Patricia Lipson ^1,2 , Philip Louie ²

¹ University of Washington, Seattle, United States,

² Virginia Mason Medical Center, Seattle, United States

Introduction: As shared decision-making models gain prominence in healthcare, patients are taking on more responsibility in deciding whether to undergo surgery. Decisional regret is a key patient-reported outcome (PRO) used to evaluate the quality of care and surgical success. With an increased emphasis on decisional regret, determining the tools to measure regret is of increasing importance. The primary aim of this systematic review is to identify and quantify the tools used to measure decisional regret in elective orthopedic surgery. Additionally, we aim to examine the timeframe for measuring regret postoperatively. Materials and Methods: The authors conducted a systematic literature review of PubMed and Embase databases with search terms focused on decisional regret and orthopedic surgery. Two mutually blinded independent reviewers conducted screening and inclusion of titles and abstracts. All studies that discuss a patients’ decisional regret in the context of an elective orthopedic surgery were eligible. This review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines. Results: Initial results yielded 1002 articles and 27 were ultimately chosen for inclusion. The Decisional Regret Scale (DRS) was the most used regret tool, being used to measure regret in 50% of the articles. Question 22 of SRS-22 was used in 12% of the studies and novel questions where regret was either evaluated or incorporated in measured outcomes were used in 38% of the articles. Of studies conducted within the last five years, from 2019 to 2024, 77% utilized either the DRS or Question 22 of SRS-22, both validated questionnaires. Additionally, regret was assessed at 24 months in 25% of studies, 12 months in 21%, 6 months in 25%, 6 weeks in 4%, multiple timeframes in 8%, 60 months in 4% and not stated in 12%. Conclusion: To our knowledge, no systematic review has been conducted on decisional regret in patients undergoing orthopedic surgery. With an increased focus on decisional regret, the use of validated questionnaires as identified in this review is logical but has not yet been demonstrated. The majority of studies where decisional regret is the primary outcome rely on the DRS for measurement. However, in many cases, regret was evaluated as a secondary or tertiary outcome using novel tools that varied across studies. The lack of standardization in decisional regret measurement tools hinders the ability to compare interventions across different studies. Additionally, the time at which decisional regret was evaluated was heterogeneous across studies, with regret potentially increasing or decreasing as patients reflect on their outcomes. This study demonstrates that the fluctuating nature of regret can be communicated to patients preoperatively to help set realistic expectations and aid in more positive surgical outcomes.

ID: 2220

RF304: Tools and indices utilized to assess socioeconomic disparities in surgery: a systematic review

Patricia Lipson ^1,2 , Jihun Cha ³ , Aiyush Bansal ^2,2 , Takeshi Fujii ² , Rafael Garcia de Oliveira ² , Jean Christophe Leveque ² , Philip Louie ²

¹ University of Washington, Seattle, United States,

² Virginia Mason Medical Center, Seattle, United States,

³ Washington State University, Pullman, United States

Introduction: Socioeconomic disparities have been shown to be associated with various outcomes surrounding episodes of surgical care. Several tools and indices have been applied to assess these socioeconomic factors, but they evaluate different domains that have been described as surrogates of socioeconomic “status” in surgical literature. This study aims to provide a systematic review of these diverse tools and indices to better understand how socioeconomic disparities have been evaluated and assess if some form of standardization can be achieved in the future. Materials and Methods: The authors performed a comprehensive systematic literature search of the PubMed and Embase databases using search terms related to surgery and socioeconomic disparity measurement tools and indices. Two independent reviewers screened the article titles and abstracts for relevance. We included studies that utilized tools or indices for measuring socioeconomic disparities in patients undergoing a surgical procedure. Studies with only an abstract, letters to the editor, and lack of full texts were excluded. This review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. Results: Seventy-five articles published between 2016 and 2024 met the inclusion criteria. Our study found that the most commonly applied indices are the Area Deprivation Index (ADI), Distressed Communities Index (DCI), Social Vulnerability Index (SVI), and Social Deprivation Index (SDI) at 24 (32%), 17 (22.7%), 9 (12%), and 8 (10.7%), respectively. The surgical specialties that were highly represented include general, orthopedic, cardiothoracic, and cardiovascular surgery. In total, our systematic review includes 19 different indices for measuring socioeconomic disparities in surgery and 14 different surgical specialties. Conclusion: To our knowledge, this is the first systematic review to assess tools and indices used to measure socioeconomic disparities in surgery. Our findings demonstrate a preference for specific indices including the ADI and DCI across multiple surgical specialties. However, multiple other indices are represented in this study as well. These findings highlight the need to establish a consensus on the most appropriate index for measuring disparities across different surgical specialties as this will ensure consistency and accuracy in comparisons and assessments.

ID: 1525

RF305: 3D printed implant for sacrum reconstruction after tumor excision

Chiara Cini ¹ , Emanuela Asunis ¹ , Giovanni Barbanti Bròdano ¹ , Gisberto Evangelisti ¹ , Marco Girolami ¹ , Valerio Pipola ¹ , Riccardo Ghermandi ¹ , Stefano Bandiera ¹ , Giuseppe Tedesco ¹ , Silvia Terzi ¹ , Alessandro Gasbarrini ¹

¹ Istituto Ortopedico Rizzoli, Spine Surgery, Bologna, Italy

Introduction: En bloc resection of sacral tumors lead to partial or complete spine-pelvic discontinuity and complicates the restoration of the spinopelvic area's anatomical integrity. Despite extensive research, standardized methods for reconstruction remain elusive, and mechanical complications like loosening, nonunion of bone grafts, and fractures are common. Recent advancements in 3D printing technology offer potential solutions through personalized implants that enhance preoperative planning and provide better biomechanical fit. This case-based article investigates the use of 3D-printed implants for sacral reconstruction following tumor excision, focusing on their effectiveness, benefits, and the challenges faced. Material and Methods: We retrospectively reviewed three patients who underwent sacral resection and reconstruction using modular, 3D-printed total sacral implants. The patient cohort consisted of two men and one woman, with a mean age of 40 years (range 27-48 years). Preoperative imaging (X-ray, CT scan, MRI) was performed to evaluate tumor characteristics and its relationship with surrounding structures. CT data in DICOM format were exported to the selected software to define the osteotomy plane, to predict the bone defect and reconstruct a 3D model. The implant design was biomechanically evaluated by individualized finite element analysis. The implant was characterized by a porous structure with low modulus of elasticity and high coefficient of friction to enhance the contact surface and distribute vertical forces, thereby ensuring sufficient biomechanical stability to obtain osseointegration. Results: Case 1: A 27-year-old man with low back pain was diagnosed with Grade 2 chondrosarcoma after MRI and biopsy. The patient underwent preoperative selective arterial embolization (SAE) and surgery involving a combined anterior and posterior approach with sagittal osteotomy of left S1, resulting in sacrifice of one of the S-1 nerve roots. Postoperative complications included cerebrospinal fluid leakage (CSF), deep vein thrombosis, and recurrent infections treated with DAIR approach and implant retention. The patient maintained ambulation but experienced partial loss of bladder function. Case 2: A 45-year-old woman with a metastatic malignant Brenner tumor underwent extensive surgical L5-S1 right hemicorpectomy, unilateral resection of the sacroiliac joint and reconstruction with a custom 3D-printed prosthesis. Postoperative complications included wound dehiscence and local recurrence threated with radiotherapy. No revision surgery was required. The patient was able to walk without external supports after surgery and complained of numbness along L5 dermatome, but he did not consider lower extremities numbness to be particularly disabling. Normal bladder function was preserved. Case 3: A 48-year-old man with mesenchymal chondrosarcoma underwent neoadjuvant chemotherapy followed by S1-S3 sagittal resection followed by a 3D-printed prosthesis reconstruction. Complications included wound dehiscence, which required surgical revision for flap closure using advancement of the gluteus maximus muscle and local recurrence threated radiotherapy. The patient was was functionally paraplegic preoperatively and suffered from complete loss of bladder function. Conclusion: 3D-printed implants offer a promising approach for sacral reconstruction after tumor excision, providing customized solutions that enhance surgical planning and potentially reduce complication rates. Nevertheless, the high complexity of the procedures and frequent complications highlight the need for continued research to optimize outcomes and improve long-term patient care.

ID: 1353

RF306: Unlocking success: a pilot study on lumbopelvic fixation’s game-changing impact on unstable Isler Class II and III sacral fractures!

Atiq Uz Zaman ¹ , Zubair Khalid ¹ , Umair Nadeem ¹

¹ Ghurki Trust Teaching Hospital, Department of Orthopedic and Spine, Lahore, Pakistan

Introduction: Sacral fractures represent a significant portion of pelvic fractures, with 10% to 45% of cases and 17% to 30% classified as unstable, primarily due to high-energy injuries. These fractures often present with associated injuries, including sacral plexus damage and other pelvic complications. While non-operative treatment is viable for many cases, unstable fractures, particularly those involving the lumbosacral articulation (Isler II and III), require surgical fixation for biomechanical stability. This study investigates the clinical and radiological outcomes of lumbopelvic fixation (LPF) in these unstable fractures, aiming to provide insights for orthopedic surgeons and influence treatment guidelines, ultimately enhancing patient care. Materials and Methods: Patients diagnosed with unstable Isler II and Isler III sacral fractures who underwent LPF utilizing a posterior triangular osteosynthesis (PTO) were analyzed. Comprehensive clinical and radiological assessments were conducted preoperatively and postoperatively (following a 2-year follow-up period). Evaluation of clinical and radiological outcomes was made. Results: In a total of 13 patients, the majority were male (8 patients, 61.5%), with an average age of 27.46 ± 3.73 years at the time of surgery. Neurologic function was impaired in 9 patients (69.2%). Seven patients (53.8%) had Isler II fractures, while the remaining 6 patients (46.2%) had Isler III fractures. The mean preoperative Visual Analog Scale (VAS) score improved significantly from 6.62 ± 1.12 to 1.85 ± 0.80 postoperatively (p < 0.0001). The mean postoperative Oswestry Disability Index (ODI) score improved from 82.15 ± 6.61 to 17.61 ± 1.45 (p < 0.0001). Radiologically, complete fracture healing was observed in all patients, with none requiring revision surgery. Residual deformity was present in 4 patients (30.8%), but it was deemed clinically insignificant. Two patients (15.4%) experienced superficial surgical site infections (SSI), which were effectively treated with antibiotics. Conclusion: Lumbopelvic fixation for Isler II and III unstable sacral fractures significantly improved pain and disability scores, with complete fracture healing observed in all patients. Residual deformities were clinically insignificant, and the procedure demonstrated a favorable safety profile.

Keywords: lumbopelvic, osteosynthesis, Oswestry disability index, sacral, visual analog scale.

ID: 1777

RF307: A comparison of monoaxial versus polyaxial screw fixation in thoracolumbar A3/A4 spine fractures

Emiliano Vialle ¹ , Luiz Vialle ¹ , Joana Guasque ¹ , Renato Beraldo ¹

¹ Hospital Universitário Cajuru, Orthopedics, Spine Surgery, Curitiba, Brazil

Introduction: There is controversy regarding the choice of implants for fixing thoracolumbar fractures, mostly regarding whether to use a mono-axial or poly-axial screw. The first has the advantage of allowing a better lever arm for deformity correction and ligamentotaxis, whilst the second is easier to assemble and puts less stress to the bone-screw interface. This study aims to compare the use of mono-axial and poly-axial screws in AOSpine type A3 and A4 thoracolumbar fractures. Methods: Prospective case control study, involving patients treated surgically with short fixation using mono-axial or poly-axial screws. The type of treatment was chosen according to the surgeons' preference and implant availability. The qualitative variables used were: type of implant (mono-axial or poly-axial), type of fracture (A3 or A4), neurological deficit, use of an additional screw in the fractured vertebra, need for reoperation. The quantitative variables were: preoperative Cobb (CobbPre); immediate postoperative Cobb (CobbPOI); late postoperative Cobb (CobbPOL); Delta (Δ) kyphosis; preoperative anterior vertebral body collapse (AVBC%); postoperative AVBC%; Δ AVBC%. For quantitative variables, the Student's T Test was used. Results: 35 patients were included, 22 in the mono-axial group (eight patients A3 and 14 A4) and 13 in the poly-axial group (two patients A3 and 11 A4). The postoperative AVBC% was statistically superior for the mono-axial group (mean of 0.60 ± 0.09 in the pre-operative AVBC% to 0.77 ± 0.11 in the post-operative), compared to the poly-axial group (0.60 ± 0.12 to 0.69 ± 0.13), p = 0.04. Δ AVBC% was also statistically different (0.17 ± 0.10 in the mono-axial group and 0.08 ± 0.12 in the poly-axial group), p = 0.01. The other quantitative variables had no significant differences. Conclusion: Surgical treatment using mono-axial screws was statistically superior in recovering anterior vertebral body height.

ID: 1964

RF308: Multicenter external validation of the accuracy of computed tomograpgy criteria for thoracolumbar posterior ligamentrous complex injury

Mohamed Ali ¹

¹ Prince Mohamed Ben Abdel Aziz Hospital, Neurosurgery, NA, Riyadh, Saudi Arabia

Background and Objective: Recent studies have proposed computed tomography (CT) criteria for posterior ligamentous complex (PLC) injury: disrupted if ≥ 2 CT findings, indeterminate if single finding, and intact if 0 CT findings. The study aims to validate the CT criteria for PLC injury externally. Methods: Three level 1 trauma centers enrolled 614 consecutive patients with acute thoracolumbar fractures (T1- L5) who received Computed tomography (CT) and magnetic resonance imaging (MRI). Three reviewers from each center were the patients from the respective center for sessed CT for facet joint malalignment, horizontal laminar fracture, spinous process fracture, and interspinous widening and MRI for disrupted PLC. The primary outcome is the diagnostic accuracy of CT criteria (0, 1, ≥ 2 findings) in detecting disrupted PLC on MRI using all CT readings. Subgroup analysis for each participating center and reviewer was done. The inter-reader agreement on PLC status on MRI and CT criteria was assessed using Fleiss Kappa (k). Results: The positive predictive value (PPV) for PLC injury was 0 findings, 3%; single positive CT, 43%; ≥ 2 CT findings, 94%, and was consistent among different centers and reviewers. The AUC for ≥ 1 CT findings in detecting PLC injury ranged from 90% to 97%, indicating excellent discrimination for all centers. The inter-reader k on PLC status by MRI and CT criteria was substantial (k > 0.60). Conclusions: This study externally validates the previously proposed CT criteria for PLC injury. ≥ 2 positive CT findings or 0 CT findings can be used as criteria for a disrupted PLC (B-type injury) or intact PLC (A-type injuries), respectively, without added MRI. A single CT finding implies indeterminate PLC status and the need for further MRI assessment. The CT criteria will potentially guide MRI indications and treatment decisions for burst fractures in patients without neurological impairment.

Keywords: Posterior ligamentous complex, Diagnostic accuracy, Multicenter, External validation, Computed Tomography, thoracolumbar fractures, AOSpine Classification.

ID: 2332

RF309: A met-analysis of the prevalence of intraabdominal injures associated with thoracic or lumbar flexion distraction injuries

Mohamed Ali ¹

¹ Prince Mohamed Ben Abdelaziz Hospital Riyadh, Neurosurgery, NA, Riyadh, Saudi Arabia

Background: The association of intra-abdominal injuries (IAIs) with thoracic or lumbar flexion distraction injuries (FDI) is well documented and may increase morbidity and mortality. However, the reported prevalence varies widely (10-50%) among studies. Aim: We aim to synthesize data about the prevalence of IAIs associated with thoracolumbar FDI. Methods: We searched PubMed, WOS, and Cochrane databases for all studies reporting the prevalence of IAIs associated with thoracolumbar FD1. The primary outcome was the overall pooled incidence of IAIs, the incidence of specific organ injuries, and the rate of surgical intervention. A subgroup analysis was done for studies restricted to adults, pediatric, or mixed populations. We assessed the methodological quality of the included studies using the Newcastle-Ottawa Scale and the Joanna Briggs Institute Critical Appraisal Checklist. A random-effects model was used for the meta-analysis to calculate pooled incidence rates and assess heterogeneity. This systematic analysis followed PRISMA guidelines. Results: A total of 8 studies with 652 patients met the inclusion criteria. The overall pooled incidence of IAIs associated with thoracolumbar flexion-distraction injuries was 36.2% (95% CI: 32.2% - 57.2%), with high heterogeneity (I² = 90.71%, p = 0.0001). The incidence of surgical intervention across 8 studies (527 patients) was 29.03% (95% CI: 22.0% - 48.3%), with high heterogeneity (I² = 92.3%, p < 0.0001). Specific organ injuries were also analyzed: small intestine injuries occurred in 19.17% of cases, large intestine injuries in 10.92%, liver injuries in 7.6%, spleen injuries in 7.2%, kidney injuries in 5.36%, and pancreas injuries in 3.7%. Less common injuries included adrenal gland injuries (1.6%), mesentery injuries (2.88%), and aorta injuries (1.03%). Some injuries, such as those to the stomach (0.82%) and Omentum (1.44%), showed minimal to no heterogeneity. Conclusion: The prevalence of IAIs associated with thoracic or lumbar FDI and the rate of surgical intervention is relatively high, at 36.2% and 29.03%, respectively. The incidence in pediatric is higher than adults The reported estimates are highly heterogeneous due to the studies' heterogenicity regarding the included population and methodology. The reported prevalence of IAIs may be overestimated predominantly due to the nature of the case series and the retrospective design of most studies. Therefore, more prospective cross-sectional studies are needed to estimate the true prevalence of IAIs accurately.

ID: 1656

RF311: Impact of different surgical and non-surgical interventions on health-realted quality of life after thoracolumbar burst fractures without neurological deficit: a comprehensive systematic review with network meta-analysis

Sebastian Bigdon ¹ , Lea Lanter ¹ , Gabriel Torbahn ² , Peter Obid ³ , Jonathan Henssler ⁴ , Sebastian Kreuzer ¹ , Christoph Albers ¹ , Niklas Rutsch ^1,5 , Martin Müller ⁶

¹ Inselspital University Hospital, Department of Orthopedic Surgery and Traumatology, Bern, Switzerland,

² Friedrich-Alexander-Universität Erlangen-Nürnberg, Institute for Biomedicine of Aging, Nürnberg, Germany,

³ University Hospital Freiburg, Department for Orthopedics and Trauma Surgery, Freiburg, Germany,

⁴ Charité - Universitätsmedizin Berlin, Department of Psychiatry and Psychotherapy, Berlin, Germany,

⁵ Charité - Universitätmedizin Berlin, Department of Neurosurgery, Berlin, Germany,

⁶ Inselspital, Department of Emergency Medicine, Bern, Switzerland

Introduction: There is no international consensus on treating thoracolumbar burst fractures (TLBF) without neurological deficits. This study is first to investigate the effect of both surgical and non-surgical treatments on midterm health-related quality of life (HRQoL). Methods: We performed a systematic review (SR) with network meta-analysis (NMA) which followed our published peer-reviewed protocol¹. The Scopus, EMBASE, Medline and Cochrane databases were searched from 2000 until December 2023, and all controlled (CCT) and randomized trials (RCT) comparing surgical or non-surgical treatment of TLBF were included in a NMA. We focused on adult patients (≤ 65 years) with acute TLBF without neurologic deficits, excluding pathological fractures. The investigated primary outcome was midterm (six months to two years after injury) overall HRQoL. Risk of bias was assessed with Cochrane RoB V.2.0 tool for RCT and the Newcastle-Ottawa Scale for CCT. The NMA was performed using the RStudio “netmeta” package to synthesize direct and indirect evidence for each treatment comparison which is presented as comparison to conservative treatment. Each comparison was evaluated for its quality of evidence using the CiNeMA tool. Results: We screened 2,789 studies and included 20 studies (ten RCT and ten CCT) with 1747 (273 non-surgical cases) participants and 10 different treatments (Figure A). Regarding HRLQoL, network heterogeneity was moderate (I² 81.7%). Short posterior fixation with index vertebrae fixation was superior to conservative treatment (1.48, 95%CI; -0.14; 3.09; moderate confidence). Minimally invasive surgery (MIS) (MIS short posterior: 1.03, 95%CI: -0.21; 2.28) and MIS with intermediate screw (0.83, 95%CI: -0.64; 2.31) were superior to conservative treatment without brace (low confidence in evidence, Figure B). Bracing showed a higher QoL than conservative treatment alone (0.21, 95%CI -1.05; 0.62). Discussion: The NMA allows for a direct and indirect comparison of all described treatments of TLBF including surgical and non-surgical techniques for HRQoL. Our findings indicate that surgical treatment results in a higher HRQoL in the midterm interval after injury compared to conservative treatment. Within the conservative treatment options, bracing does not show a clinically relevant difference in HRQoL. Figure: NMA comparing all included surgical techniques regarding the midterm overall HRQoL. A Network plot of direct comparisons. Numbers indicate studies per comparison and the point size corresponds to the patient numbers per treatment. The line color shows to the mean risk of bias of the studies. B Forest plot comparing all treatments against conservative. References

1. Lanter L, Rutsch N, Kreuzer S, et al. Impact of different surgical and non-surgical interventions on health-related quality of life after thoracolumbar burst fractures without neurological deficit: protocol for a comprehensive systematic review with network meta-analysis. BMJ Open. 2023;13(12):e078972. doi:10.1136/bmjopen-2023-078972

ID: 2712

RF312: Stairway to heaven: the dangers of falling downstairs

Deepshika Varasala ¹ , Zion Hwang ¹ , Shruthi Atapaka ¹ , Mak Macapagal ¹ , Jack Williams ¹ , nawal siddiqui ¹ , Jason Bernard ¹ , Timothy Bishop ¹ , Bisola Ajayi ¹ , Tesfaladet Kurban ¹ , Hasan Raza ¹ , Adnan Sheikh ¹ , James Geddes ¹ , Liam Rose ¹ , Darren Lui ¹

¹ St Georges University of London, London, United Kingdom

Introduction: Falling downstairs can be lethal or have significant morbidity. Falls can be split up into those from ground level (low energy trauma) and a greater height (high energy trauma). However, the severity and pattern of injury in stair-focused falls is little studied compared to those from ground or higher level. This study aims to evaluate outcomes in patients who fall downstairs are admitted to a level 1 trauma centre as Major Trauma Calls. Material and Methods: Retrospectively, we identified all major trauma patients from a trauma 1centre from 2017-2022. We reviewed them via an electronic database and identified those with spinal injury with a fall from stairs. We split the patients into the following categories; fall from standing, < 5 steps, 5-10 steps, 11-15 steps and > 15 steps. The mean AOTLICS score was calculated and used to compare falls from standing and downstairs. Results: From a total of 362 suspected major trauma presentations, 200 patients were had falls from stairs. Of these, 71 (36%) from standing, 18 (9%) from < 5 steps, 21 (11%) from 5-10 steps, 78 (39%) from 11-15 steps, 11 (6%) from > 15 steps. Out of the spinal injuries were reported, 91 (34%) cervical, 104 (39%) thoracic, 67 (25%) lumbar and 6 (2%) sacral injuries. Cervical injuries were most sustained in the standing 43% (12/28), < 5 steps 43% (3/7) and 11-15 steps 38 (62/162) groups. Whilst the groups with 6-10 steps, 55% (29/53) and > 15 steps 53% (8/15) had more thoracic injuries. By injury classification, Type A injuries were seen in 25 (26%) from standing, 6 (6%) from < 5 steps, 10 (10%) from 5-10 steps, 46 (48%) from 11-15 steps, 9 (9%) from < 15 steps. Only 1 patient had a Type B injury, which was a fall from standing. Type C injuries were sustained by 2 from standing, 5 from the 6-10 steps and 7 from the 11-15 groups. 86 of all patients presented with polytrauma, including, 60 (69%) head, 25 (29%) neck, 15 (17%) upper limb, 11 (13%) lower limb and 41 (48%) thorax injuries. The average AOTLICS score was 5 (standing), 5 (< 5), 2 (5-10), 2 (11-15) and 2.8 (> 15). The mean hospital length of stay 5.8 (standing), 2.6 (< 5), 11.6 (5-10), 10.8 (11-15) and 9.2 (> 15), indicating significance between the groups by ANOVA test [F = 5.71521, p = 0.00026]. 16 patients died within 30-days: 2% (standing), 1% (< 5), 0.5% (5-10), 4.5% (11-15), 0% (> 15). Of these, 14 received conservative treatment and 2 received surgical treatment. Overall, 157 (79%) of patients were treated conservatively with 45 (standing), 11 (< 5 steps), 14 (5-10) 52 (11-15), 7 (< 15). 22% of patients received surgical treatment with 18 (standing), 6 (< 5), 5 (6-10), 13 (11-15), 1 (< 15). 40 out of the 200 patients were admitted to ICU with a mean stay of 6.3 days (standing), 5.3 days (< 5), 6 days (5-10), 9 days (11-15), 6.3 days (> 15). Conclusion: 55% of urban level 1 major trauma presentations are caused by fall down the stairs. Of these 26% warrant surgery, yet only 21% actually received surgery and 7% more patients die without surgical management. 71% of those that die have associated head injuries. Falls from 11-15 steps have almost double the number of deaths compared to fall from standing and are associated with 43% more ICU admissions and 5 days longer stay.

ID: 489

RF313: Cross-cultural adaptation and pyschometric property study of the Thai Version of the AOSpine Patient Reported Outcome Spine Trauma questionnaire (AOSpine PROST)

Borriwat Santipas ¹ , Panya Luksanapruksa ¹ , Sirima Nilnok ² , Sirichai Wilartratsami ¹

¹ Faculty of Medicine Siriraj Hospital, Mahidol University, Department of Orthopedic Surgery, Bangkok, Thailand,

² Faculty of Medicine Siriraj Hospital, Mahidol University, Division of Research, Department of Orthopedic Surgery, Bangkok, Thailand

Study Design/Setting: Multi-center validation study. Objective: To translate and cross-culturally adapt the AO Spine PROST (Patient Reported Outcome Spine Trauma) into the Thai version, and to evaluate and determine the reliability and validity of the reliability and validity of the AO Spine PROST scores. Methods: Patients from three level-1 hospitals were recruited and assessed using the AO Spine PROST, the 36-item Short Form Survey (SF-36), and the EuroQol 5D-5L (EQ-5D-5L: Thai version) at baseline and 7 days post-treatment. Descriptive statistics were analyzed to characterize patients. Concurrent validity was assessed by comparing the AO Spine PROST with the SF-36 and EQ-5D-5L through the analysis of floor and ceiling effects, Cronbach's alpha coefficients, Spearman’s rank correlation, effect sizes (ES), standardized response means (SRM), and factor analysis, as well as identifying any irrelevant or missing items. Test-retest reliability was assessed in a subgroup of patients who completed the questionnaires at both time points. Results: Eighty-four patients (mean age: 49 years; 60 males, 24 females) were included. The internal consistency was good (Cronbach’s α = 0.837-0.964), with intraclass correlation coefficients (ICC) ranging from 0.719 to 0.930. Baseline scores were 76.87 (AO Spine PROST), 62.08 (SF-36: physical component summary; PCS), and 65.32 (SF-36: mental component summary; MCS), showing significant changes after 1 week. Notable changes were seen in SF-36 domains for role-physical (ES: -0.309), bodily pain (ES: -0.248), and mental health (ES: -0.202). Minimal changes were observed in EQ-5D-5L and EQVAS (ES: 0.083, 0.118). Good correlations were found between AO Spine PROST and SF-36, particularly physical functioning (0.825), role physical (-0.695), and bodily pain (0.613). The PCS and MCS components correlated at 0.747 and 0.509, respectively. Moderate to strong correlations were also found between AO Spine PROST and EQ-5D-5L, particularly in mobility (-0.732), usual activities (-0.735), and self-care (-0.629). Conclusion: The AO Spine PROST questionnaire's Thai version demonstrated good validity and reliability outcomes.

Keywords: AO spine PROST, spine trauma, outcome instrument, patient perspective, function, health

ID: 1370

RF314: Health outcomes in traumatic thoracic and lumbar spinal cord injury

Xenia Zubenko ¹ , Susan Liew ^2,3 , Sandra Reeder ¹ , Belinda Gabbe ^1,4

¹ Monash University, Melbourne, Australia,

² The Alfred, Department of Orthopaedics, Melbourne, Australia,

³ The Alfred, Monash Department of Surgery, Melbourne, Australia,

⁴ Swansea University, Health Data Research UK, Medical School, Swansea, United Kingdom

Introduction: Traumatic injury to the spinal cord has been a well-studied phenomenon, yet little is known about the difference in long-term health outcomes between upper and lower levels of spinal cord injury (SCI). The purpose of this study was to compare the long-term outcomes of patients who have a traumatic injury to the spinal cord or cauda equina with preserved hand function. Material and Methods: This was a registry-based cohort study of people with a diagnosis of traumatic SCI below the level of T4 or traumatic cauda equina syndrome with a date of injury from 2010 to 2024. Patients were recruited from the Victorian State Trauma Registry (VSTR). The AIS and ICD-10-AM coding were used to identify SCI below the level of T4 and cauda equina. People with a concomitant cervical spinal cord or an unspecified level of lumbar spinal cord injury were excluded. Participants were divided into two groups; upper motor neuron (UMN) injury (SCI at L1 and above) and lower motor neuron (LMN) injury group (SCI at L2 and below). From the VSTR, demographic, injury event, and hospital stay details were extracted. Follow-up was conducted by the registry at six, 12- and 24-months post injury, and included the World Health Organization Disability Assessment Schedule (WHODAS), EuroQol EQ-5D scale, and return to work outcomes. Descriptive statistics and mixed effects regression modeling were used to compare the characteristics and outcomes between groups. Results: Of the 1,203 participants, 1,154 (96%) were categorised as UMN, and 49 (4%) as LMN. Within both groups, most were men (69%). Road trauma N = 502 (44%) was the leading cause of injury for the UMN injury group while low falls N = 17 (35%) were the leading cause for the LMN injury group. Mixed effect regression modeling of the EQ-5D outcomes over time showed little improvement in outcomes for both injury groups. At 24-months post-injury, the UMN and LMN injury groups showed similar proportions reporting some degree of problems within EQ-5D dimensions: mobility (UMN N = 376 (61%), LMN N = 18 (67%)), self-care (UMN N = 264 (43%), LMN N = 11 (41%)), usual activities (UMN N = 434 (70%), LMN N = 22 (81%)), pain and/or discomfort (UMN N = 458 (75%), LMN N = 21 (78%)), and anxiety and/or depression (UMN N = 309 (50%), LMN N = 10 (38%)). The return to work rate was higher for the LMN injury group at all follow-up time points, with N=260 (57%) of the UMN injury group returning to work at 24 months post-injury compared to N = 11 (69%) of the LMN injury group. At 24 months post-injury, the level of disability was similar between both groups, with N = 249 (62%) of people in the UMN injury group reporting a WHODAS score equal or greater to ten, whilst N = 11 (65%) of people in the LMN injury group reported WHODAS score equal or greater to ten. Conclusion: In conclusion, the demographics of patients within the UMN and LMN injury groups were similar except for the cause of injury. Overall health quality of life outcomes remained similarly poor over time for both injury groups, with little improvement in outcomes over time.

ID: 434

RF315: Evaluating the efficacy of indirect spinal canal decompression in thoracolumbar junction burst fracture management

Oleksii Nekhlopochyn ¹ , Vadim Verbov ² , Ievgen Cheshuk ² , Milan Vorodi ²

¹ Romodanov Neurosurgery Institute, Spine Neurosurgery, Kyiv, Ukraine,

² Romodanov Neurosurgery Institute, Restorative Neurosurgery Department, Kyiv, Ukraine

Introduction: Indirect decompression of the spinal canal through ligamentotaxis is one of the methods for remodeling the spinal canal in traumatic stenosis. This study aims to evaluate the effectiveness of indirect decompression of the spinal canal for different morphological types of burst fractures of vertebral bodies at the thoracolumbar junction. Materials and Methods: A preoperative and postoperative analysis of computed tomography scans was performed on 59 patients who were treated at the “Romodanov Neurosurgery Institute, National Academy of Medical Sciences of Ukraine” for burst fractures at the thoracolumbar junction. The criterion for the effectiveness of indirect decompression was the area of the spinal canal, measured at the level of injury in the zone of maximum compression. The grading of burst fractures was performed using the classification by F. Magerl et al. (1994). Results: In the preoperative period, the median degree of stenosis in the group of patients was 43.47% (95% confidence interval (CI): 37.53-46.22%). For damage type A3.1, it was 36.9% (95% CI: 28.1-40.5%), for type A3.2 - 46.1% (95% CI: 32.1-54.5%), and for type A3.3 - 47.6% (95% CI: 37.5-56.5%). After surgical treatment, the degree of stenosis decreased by 20.14% (95% CI: 15.93-21.56%). For type A3.1, the effectiveness was 20.1% (95% CI: 9.5-22.7%), for type A3.2 - 15.2% (95% CI: 7.51-17.3%), and for type A3.3 - 21.7% (95% CI: 20.8-26.4%). The difference between types A3.2 and A3.3 was statistically significant (p = 0.0018). It was found that indirect decompression is most effective with higher degrees of stenosis. For Grade I by D. Wolter (1988), the canal expansion achieved was 7.07% (95% CI: 5.69-8.65%), for Grade II ‒ 21.6% (95% CI: 20.4-22.7%), and for Grade III - 30.3% (95% CI: 27.0-33.6%). Conclusions: Closed remodeling of the spinal canal with transpedicular fixation and the effect of ligamentotaxis is an effective method for correcting traumatic spinal canal stenosis at the thoracolumbar junction. The effectiveness of the technique is determined by many factors, including the type of burst fracture, the initial degree of stenosis, and the level of injury.

ID: 2095

RF316: Conservative versus surgical management of patients with an AOTLICS score of 4 and 5

Rhys Owen ¹ , Zion Hwang ¹ , Darren Lui ¹ , Nawal Siddiqui ¹ , Jack Williams ¹ , Mak Macapagal ¹ , Bisola Ajayi ¹ , Deepshika Varasala ¹ , Jason Bernard ¹ , Timothy Bishop ¹ , Shruthi Atapaka ¹

¹ St Georges, University of London, London, United Kingdom

Introduction: Thoracolumbar injury contributes a significant number of major trauma presentations. Having appropriate guidelines to facilitate optimum management decisions for these patients is vital. The AO Spine Classification System establishes that AOTLICS scores less than 4 require conservative management and greater than 5 surgical management. However, a grey area exists in the management guidance for injuries scoring 4 or 5. This study aims to evaluate the outcomes when the decision for surgery is equivocal. Material and Methods: All trauma patients admitted to a level 1 major trauma centre from 2017 to 2022 were reviewed via an electronic patient database. Patients with thoracic and lumbar spinal injuries were identified and their AOTLICS score was calculated. Those with scores of 4 and 5 were identified and analysed to determine whether they received surgical or conservative management. Results: 1,119 patients were identified as having a spinal injury, of which 823 suffered a thoracolumbar injury. Of these, 66 (6%) patients were identified as having a thoracic or lumbar spinal injury with a AOTLICS score of 4 or 5. 45 (67%) were Male, with an average age of 54 years. 35 (53%) of these patients presented with polytrauma, including 11 (17%) head, 8 (12%) face, 7 (11%) neck, 8 (12%) upper limb, 11 (17%) lower limb, 21 (32%) thorax, 3 (5%) abdomen, and 4 (6%) pelvic injuries. Spinal injuries were classified according to the AO Spine Injury Classification Systems. Of the 66 thoracolumbar injuries 58 had type A injury, 8 type B, and 0 type C. Neurological deficit was found in 6 (9%) patients. The most common mechanism of injury was a fall, which account for 68% of patients (45/66). 34 (52%) of patients were treated conservatively. The average AOTILCS score for the conservatively and surgically managed groups were 4.67 and 4.69 respectively. The average ISS score for conservatively and surgically managed was 14 and 16 respectively. The mean hospital length of stay for the conservatively managed group was 34 days versus 15 days in those who had surgery. However, the Mann-Whitney U test indicate a non-significant difference between groups, [U = 419.5, p = .424]. 13 (20%) were admitted to ITU, 6 patients who were managed conservatively, with a mean stay of 13 days, versus 11 days for the 7 surgically managed patients. The 30-day mortality was at 3% (2/66), with one patient in both the conservative and surgically managed groups. In reviewing the 35 patients who suffered polytrauma, 23 were conservatively managed, with a mean hospital stay of 27 days, versus 18 days for the 12 surgically managed patients Conclusion: Almost 10% of thoracolumbar injuries arising from major trauma rely on the surgeon’s expertise to determine their management. This research suggests that those with an equivocal AOTILCS score of 4 or 5, those who are managed surgically may have a reduced length of stay in hospital in comparison to those who are managed conservatively. Further research with a greater sample size would be required to validate the findings that this research suggests.

ID: 449

RF317: Effect of early surgical intervention in traumatic spinal fractures

Peter Udby ¹ , Charlotte Festersen ¹ , Line Sørensen ¹ , Martin Heegaard ¹ , Josefin Lysen ¹ , Martin Gehrchen ¹ , Benny Dahl ¹ , Søren Ohrt-Nissen ¹

¹ Rigshospitalet, Department of Orthopedic Surgery, Spine Unit, Copenhage, Denmark

Introduction: Spinal fractures constitute 5% of all traumatic fractures and surgical management is considered if stability, alignment, or neurological function is compromised. In the preoperative period, patients are often immobilized, while full mobilization is permitted after surgical stabilization. In other types of skeletal trauma there is a strong association between surgical delay and postoperative complications but whether this association exists for spinal trauma is unknown. This study aimed to determine if the prognosis and mortality after spinal fractures were related to the timing of surgery, and to investigate factors associated with hospital readmission. Material and Methods: This was a single-center retrospective cohort study on patients with traumatic spine fractures undergoing surgical stabilization from October 2016 to April 2022 at a single center. Patients were identified from the hospital's administrative database. Subsequently, clinical information was collected from journal records including age, gender, time of radiographic diagnosis, time of primary spine surgery, 30-day hospital readmission, and two-year survival status. Results: We included 565 patients (69% males). Twenty-two percent (n = 126) of fractures were in the cervical region, 41% (n = 231) in the thoracic region, 33% (n = 185) in the lumbar region, and 4% (n = 23) in multiple regions. Sixty-two percent (n = 352) were low-energy traumas and 38% (n = 213) were high-energy traumas. Fifteen percent (n = 82) of the patients were readmitted within 30 days. The mean time from trauma to surgery was 9.1 days in the non-readmission group compared to 13.8 days in the readmission group (p = 0.117). Nineteen percent of the patients in the non-readmission group underwent surgery within 48 hours compared to 17% in the readmission group (p = 0.704). In the non-readmission group, two-year mortality was 9% vs. 28% in the readmission group (p < 0.001). Mean age was 55.8y vs. 63.1y (p = 0.002). There was no significant difference in the distribution of low- vs high-energy trauma or fracture levels between groups. Conclusion: The findings from this study suggest that late surgery (> 48h) in patients with traumatic spine injury is not associated with a significantly higher risk of hospital readmission. The risk of readmission was markedly higher in patients with increased age. The two-year mortality rate was significantly higher in patients who were readmitted compared to those who were not.

ID: 2692

RF318: Speed hump spine fractures: a peculiar public transportation hazard

Juan Zamorano ¹ , Tania Rojas ¹ , Sebastian Bianchi Valenzuela ¹ , Ignacio Cirillo ¹ , Ignacio Farías ¹ , Marcos Gimbernat ¹ , Carlos Tapia ¹ , Harold Sherman Fuentes ¹

¹ Hospital del Trabajador Achs, Región Metropolitana, Ramón Carnicer 185, Providencia, Santiago de Chile, Chile

Introduction: The efficacy of speed humps for reducing motor vehicle accidents is debatable, particularly when we consider previous reports of patients resulting with spine fractures due to their implementation in public transport routes. Our objective is to present a case series of patients with spine fractures, injured after going over a speed hump while seated in a motor vehicle. We describe this peculiar injury mechanism and potential prevention measures. Material and Methods: Retrospective case series (20 years: 1996-2015) of patients treated in a single center with spine fractures caused by this particular injury mechanism. Medical records and images were reviewed to collect demographic data, fracture characteristics, treatment type and evolution. Results: Series of 75 patients (85 fractures), none of them with neurological impairment, 56 women (74.67%) and 19 men (25.33%), mean age 49.2 ± 13.2 years. Sixty-seven patients (89.33%) were injured while traveling in a bus: 88.1% of them (59/67) were seated in the last row. All patients had compression fractures (type A of the AO classification), 52/85 (61.18%) were subtype A1 and 29/85 (34.12%) subtype A3. L1 was the most frequently affected level (39/85, 45.88%), followed by T12 (17/85, 20%). Sixteen patients (21.33%) required surgical treatment. The average time out of work was 108.3 days, and 4 patients (5.33%) received workers' compensation due to chronic back pain. Conclusion: Going over a speed hump while seated in the last row of a motor vehicle (particularly a bus) can cause severe traumatic spine injuries secondary to a catapult-type mechanism that generates an axial compression force on the spine. These fractures occur more frequently in women and mainly affect the thoracolumbar junction. Some patients may require surgical treatment and may even result in permanent disability. It is necessary to educate the population (especially public transport passengers and drivers) about this risk, together with reviewing current regulations in order to avoid the use of speed humps in public transport routes.

ID: 2137

RF319: Literature review and case report of a patient with a L4 bust fracture AO Classification Type A3 treated with percutaneous fixation and decompression using interlaminar endoscopic technique

Ramon Guerra Barbosa ¹ , Yan Silva ² , Marcus Vinícius Serra ³

¹ Hôpital de Chicoutimi, Neurosurgery, Chicoutimi,

² Hospital São Rafael, Orthopedics, Salvador,

³ BESSC, Neurosurgery, Santos

Introduction: Compression fractures are common in trauma and are often treated conservatively. However, in selected cases with significant spinal canal compromise, vertebral body height loss, or compression of neurological structures, surgical intervention is required. Various approaches, including posterior, lateral, or anterior access to the spine, are used to address anterior column injury with canal compromise. This study presents a case of an L3 - AO Spine A3 burst fracture treated with percutaneous fixation and an uniportal endoscopic interlaminar approach for decompression, along with a review of the relevant literature. Material and Methods: A search on PubMed using the terms “spine fracture” and “endoscopy” retrieved 161 articles. After excluding papers not related to the subject, just 3 articles were selected for review, each describing the use of endoscopy for treating burst fractures with percutaneous fixation. Two articles reported case studies using uniportal transforaminal endoscopy for canal fragment decompression, and one described a series of 10 patients treated with biportal endoscopy for decompression. In our case, a 42-year-old female obese patient, which fell from a horse, sustained an L4 burst fracture AO Spine classification A3 with a posterior wall fragment occupying 80% of the spinal canal, associated to an L3 compression fracture, AO classification A1. Patient complained back pain associated to saddle paresthesia. Surgical treatment involved percutaneous screw fixation at L2, L3, L4, and L5, combined with an uniportal endoscopic interlaminar laminectomy at L4-L5, “over the top” with bilateral decompression, and removal of the fracture fragments. To our knowledge, this is the first reported case using the “over the top” laminectomy performed by uniportal interlaminar endoscopic decompression for fragment removal. Results: Following the removal of the fractured fragments, the patient showed motor potential improvement through neuromonitoring. She was discharged 24 hours after the procedure, with significant pain relief (VAS score reduced to 2/10) and adequate decompression as seen in follow-up CT scans. These results are consistent with findings in the literature, where early surgical intervention and effective decompression are crucial for neurological recovery and alignment restoration. The minimally invasive approach provided substantial benefits, including less postoperative pain, shorter recovery time, and minimal surgical trauma, similar to previously reported outcomes with endoscopic techniques​ Conclusion: Spinal endoscopy is a safe and effective method for treating burst fractures as a decompression tool, offering reduced risks of hemorrhage, infection, postoperative pain, and shorter hospital stays. In trauma cases, this technique is a viable alternative for selected patients. This case represents the first known use of “over the top” laminectomy performed by uniportal endoscopic interlaminar decompression for a burst fracture, highlighting the need for further studies to validate the efficacy of this approach.

ID: 539

RF320: Hydraulic polymethylmethacrylate pressure delivery system versus manual ballon tamp system in ballon kyphoplasty

Oded Hershkovich ¹ , Raphael Lotan ¹

¹ Edith Wolfson Medical Centre, Orthopedics, Spine, Holon, Israel

Introduction: Osteoporotic vertebral compression fractures (VCFs) are prevalent among the elderly population, and Balloon kyphoplasty (BKP) is a minimally invasive solution for these. However, Polymethylmethacrylate (PMMA) leakage is a significant complication with potentially severe consequences. This study compares the safety and efficacy of manual balloon tamp system (MTS) and hydraulic Polymethylmethacrylate pressure delivery system (HPDS) in BKP. Methods: Retrospective cohort study involving 160 patients, comparing MTS (2008-2014) and HPDS (2016-2020) cohorts, assessed PMMA leakage, radiation exposure, and surgery duration. Results: PMMA leakage occurred in 52.8% of MTS and 62.5% of HPDS cases. Intradiscal leakage was the most common pattern in both groups. Multivariate logistic regression revealed that multilevel BKP and HPDS were associated with higher PMMA leakage rates. Radiation exposure was significantly lower with HPDS, while surgery duration was shorter. Discussion: This study provides novel insights into PMMA leakage and radiation exposure in BKP. HPDS was associated with a higher PMMA leakage rate. HPDS, however, offers advantages in terms of reduced radiation exposure and shorter surgery duration. Multilevel BKP also increased the risk of leakage. Further investigation is needed to better understand the impact of HPDS on PMMA leakage. Conclusion: This study underscores that while HPDS offers advantages regarding radiation exposure and surgery duration, it is associated with a higher PMMA leakage rate.

RF19: ADULT SPINAL DEFORMITY 2

ID: 2517

RF321: The smallest worthwhile effect outperforms the minimal clinically important difference in estimating health-related quality of life following surgical correction for adult idiopathic scoliosis

Nan Wu ¹ , Di Liu ¹ , Zhengye Zhao ¹ , Shengru Wang ¹ , Jianguo Zhang ¹

¹ Peking Union Medical College Hospital, Orthopedics, Beijing, China

Introduction: The smallest worthwhile effect (SWE) enables patients to evaluate the expected value of a treatment by weighing its benefits, risks, and costs. This threshold has emerged as an alternative to the minimal clinically important difference (MCID) for assessing health-related quality of life (HRQoL). This study aims to determine the SWE estimates in patients with adult idiopathic scoliosis (AdIS) and to assess whether the actual clinical outcomes align with the expected results. Material and Methods: This is an observational longitudinal study and participants were enrolled from the Deciphering disorders Involving Scoliosis and Comorbidities (DISCO) study at Peking Union Medical College Hospital. The Scoliosis Research Society-22 (SRS-22) and SRS-30 questionnaires were collected preoperatively and at a minimum of two-year follow-up. The MCID was determined using both anchor-based and distribution-based approaches. The benefit-harm trade-off method was employed to estimate absolute and relative SWE thresholds preoperatively, with the 50th and 90th percentiles indicated on the histograms. Additionally, the construct validity was assessed to evaluate the association between achieving the SWE threshold and overall patient satisfaction. Results: A total of 92.4% of participants (n = 110) reported satisfaction with their current condition. The absolute SWE at the 50th percentile was 0.8 points for the SRS-22 appearance, corresponding to a 31.3% relative improvement. The absolute SWE exceeded the MCID for the SRS-22 appearance domain (0.8 vs. 0.7). Furthermore, achieving or surpassing the absolute SWE threshold for appearance scores was significantly associated with overall postoperative satisfaction (Χ² = 11.3, p < 0.05). Additionally, 25-75% of patients required improvements ranging from 0.0-5.6%, 0.00-13.6%, 0.0-17.7%, and 5.4-17.4% for activity, pain, mental health, and total scores, respectively. Tertile analysis also revealed that participants with poorer baseline scores exhibited higher SWE estimates. Conclusion: The SWE had both statistical and clinical significance in the evaluation of patient-reported outcome measures (PROMs) after corrective surgery for AdIS, and it provided a more effective framework than the MCID for interpreting changes in SRS-22 scores. Spine surgeons could utilize SWE to enhance surgical decision-making and to support prognostic evaluations.

ID: 2419

RF322: Surgery improves social function of older adult spinal deformity (ASD) patients

Lauren Daunt ¹ , Vanessa Vashishth ¹ , Eliana Seider ¹ , Mauricio Campos Daziano ² , Brian Neuman ³ , Christopher Ames ⁴ , Stephen Lewis ¹

¹ Toronto Western Hospital, Division of Orthopaedics, Toronto, Canada,

² Pontificia Universidad Católica de Chile, Orthopedic Surgery, Santiago, Chile,

³ Washington University School of Medicine, Department of Orthopaedic Surgery, St Louis, MO, United States,

⁴ University of California San Francisco, Department of Neurosurgery, San Francisco, United States

Introduction: Adult spinal deformity (ASD) can have significant impact on various aspects of a patient’s life that include social interactions, relationships, activities such as study, work, or sports and ability to integrate into society. While there is significant research on outcomes of ASD surgeries, there is limited granular data on social function. This study aims to examine the impact of ASD surgery on the social functioning among a cohort of patients > 60 years of age. Material and Methods: A prospective, multicenter, multicontinental cohort of patients ≥ 60 years old undergoing primary spinal fusion ≥ 5-levels for ASD were reviewed. Basic demographic variables were recorded as well as work status, and Animal Fluency Test (AFT), as a metric for cognitive function. Patients were reviewed and outcome forms were completed at baseline, 10 weeks, 12 months, and 24 months. The outcome measures of interest in the current report were questions 14 (do you feel your back condition affects your personal relationships) and 18 (does your back condition limit your going out with friends/family)) of the Scoliosis Research Society-22r questionnaire (SRS-22r). Additionally, we focused on question 9 (impact of back pain on social life) from the Oswestry Disability Index (ODI). Descriptive statistics were used to present mean and standard deviation or median and interquartile range for continuous data and absolute and relative frequency for categorical data. Results: 219 patients met the inclusion criteria, with a median age of 67.5 and 80.4% being female. The mean BMI was 26.1 (SD 5.4). More than a third were employed or homemakers, 60.3% were retired and 25.7% showed some cognitive impairment as measured through the AFT. 61.2% of the patients were categorized as ASA II. For the SRS-22r Q14, at baseline, 40.1% of patients felt their back condition moderately or severely affected their personal relationships compared to 14.7% at 1-year and 15.4% at 2-years. Of the 73 patients that were moderately or severely affected pre-op, 19 (26%) remained so at 2 years while 25 (34%) rarely or never were affected at 2-years. For SRS-22r Q18, at baseline, 47.7% of patients felt their back often or very often limited them going out with friends/family compared to 21.5% at 1-year and 17.1% at 2-years. Of the 69 patients that were moderately or severely limited pre-op, 19 (28%) remained so at 2 years while 40 (58%) rarely or never were limited at 2-years. For the ODI, Q9, 8.7% of patients felt that their social was normal and does not cause them extra pain pre-op compared to 33.3% of patients at 1-year and 44.1% of patients at 2-years. Conclusion: While many factors such as social network, cognitive function and other medical conditions can affect a patient’s social function, in this cohort of a diverse international group of patients ≥ 60 years of age, ASD surgery had a significant positive impact on their social function. This data provides useful information in the expected outcomes following ASD surgery in older patients and attributes to the positive physical and mental benefits of these complex procedures.

ID: 2223

RF323: Enhanced recovery after surgery protocols in patients with adult spinal deformity: a systematic review

Takeshi Fujii ^1,2 , Rakesh Kumar ² , Patricia Lipson ^2,3 , Kellen Nold ² , Aiyush Bansal ² , Murad Alostaz ² , Philip Louie ² , Rajiv Sethi ²

¹ Keio University, Tokyo, Japan,

² Virginia Mason Medical Center, Seattle, United States,

³ University of Washington, Seattle, United States

Introduction: Enhanced recovery after surgery (ERAS) protocols have been shown to be beneficial in managing patients with adult spinal deformity (ASD). However, the perioperative interventions vary widely across institutions without widespread standardization. Therefore, the current study aims to review the consensus on the interventions for patients undering ASD surgery in addition to evaluating the impact of ERAS protocol on postoperative outcomes. Materials and Methods: A comprehensive systematic review was conducted in PubMed and Embase following PRISMA guidelines. We included studies that addressed the implementation of ERAS protocols for adults with spine deformities that underwent corrective surgery.Studies that included minimal invasive surgery (MIS), decompression-only interventions, cervical deformity, reviews, case reports, abstracts for conferences, and editorial letters were excluded.We conducted a meta-analysis on postoperative outcomes, where possible, by calculating the pooled standardized mean difference between the group treated with conventional care pathways (pre-ERAS) and those treated with ERAS pathways (post-ERAS). Results: Out of 62 articles, 7 were included in the systematic review. Common interventions in the ERAS protocols included: 1) preoperative anesthesia-related risk assessment, multidisciplinary assessment, and cessation of smoking, 2) intraoperative TXA administration and continuous monitoring of lab data, and 3) postoperative early mobilization and early nutritional support. Multimodal analgesia plans were commonly observed in many of the ERAS protocols. Two studies demonstrated significant reductions in readmission rates and total opioid consumption in the post-ERAS group compared to the pre-ERAS group, while three studies described comparable medical complication rates between the groups. Meta-analysis demonstrated no significant difference in LOS between the pre-ERAS and post-ERAS groups. Conclusion: The goals of ERAS protocols for ASD surgery often address preoperative optimization, intraoperative stress minimization, and postoperative recovery facilitation. Despite the advantages of ERAS programs, meta-analysis revealed that there was no significant difference in LOS with the implementation of ERAS. Further studies are required to standardize the ERAS protocol for ASD surgery and enhance the impact on postoperative outcomes.

ID: 2497

RF324: Multilevel hybrid combined surgical approach for adult degenerative scoliosis: a single center experience

Antonino Raco ¹ , Nicolo Norri ² , Michele Dughiero ² , Massimo Miscusi ² , Sokol Trungu ³ , Stefano Forcato ³ , Luca Ricciardi ¹

¹ University La Sapienza, Rome, Italy,

² University of Ferrara, Ferrara, Italy,

³ Department of Neurosurgery Pia Fondazione di Culto e Religione Cardinal G. Panico, Tricase, Italy

Introduction: The surgical treatment of adult degenerative scoliosis (ADS) is challenging and comes with a high risk of complications. However, a combination of minimally invasive lateral (XLIF) or anterior (OLIF) lumbar interbody fusion followed by additional open or minimally invasive posterior segmental instrumented fusion has shown promising results in treating ADS. Further studies are needed to assess the impact of this multilevel hybrid combined approach on various factors such as segmental and regional coronal angulation, sagittal realignment, Cobb angle, restoration of lumbar lordosis, and clinical outcomes. The authors of the study evaluated the clinical and radiological outcomes, as well as mortality and morbidity, of using a multilevel hybrid combined approach to treat ADS. Material and Methods: We conducted a retrospective analysis of data of patients who underwent a multilevel hybrid combined approach for ADS. We documented surgical details such as the number of instrumented levels, the type of surgical approach, and intra-operative and postoperative complications. Preoperatively and postoperatively, we collected full-spine x-rays, including standard and dynamic studies, and recorded radiographic measurements such as coronal angulation, pelvic incidence, lumbar lordosis, and sagittal vertical axis for all patients. Additionally, we used the visual analog score (VAS) for back and leg pain, the Oswestry Disability Index (ODI), and Short Form-36 (SF-36) scores to evaluate clinical outcomes. Results: We gathered comprehensive clinical and radiological information from forty-three out of fifty-one patients (M:F ratio was 2:1) with an average age of 65 (± 9) years, and a mean follow-up period of 31 (± 14) months. The average time between the two stages of surgery was 40 (± 15) days. There was a significant improvement in the mean VAS-back, VAS-legs, ODI, and SF-36 scores when comparing pre- and post-follow-up evaluations. The mean pelvic tilt (p < 0.01), segmental slippage (p < 0.02), and slip angle (p < 0.01) showed significant improvement after the multilevel hybrid combined approach. Postoperatively, the sagittal vertebral axis (SVA, p < 0.01), lumbar lordosis (LL, p < 0.01), and pelvic incidence-LL mismatch (PI-LL, p < 0.01) significantly improved in the group treated with the OLIF approach. Additionally, the group treated with the XLIF approach showed significantly better postoperative correction of the coronal misalignment (Cobb angle, p < 0.01). Conclusion: Our research indicates that open surgery has several advantages, including a more significant improvement in lumbar lordosis and pelvic tilt angle. However, it is associated with increased blood loss and major surgical complications. On the other hand, minimally invasive surgery, utilizing the OLIF technique, offers excellent correction for sagittal deformity, while the XLIF technique is effective for treating coronal deformity. These techniques can be complemented by mini-open posterior approaches like Smith Peterson osteotomies on a limited number of segments, with results comparable to open surgeries. In our experience, delaying the first and second surgical procedures can significantly enhance the realignment of spinal deformities, reducing the need for extensive and aggressive posterior corrections during the second stage of surgery. Additionally, the two-step surgical correction is a secure and reliable solution, especially for elderly patients.

ID: 2863

RF325: Hybrid treatment (minimally invasive/mini-open) with double anterolateral and posterior approach in degenerative scoliosis: outcome and clinical/radiological follow-up of 50 cases treated in a single center

Giuseppe Barbagallo ¹ , Giacomo Cammarata ¹ , Martina Rossitto ¹ , Francesco Certo ¹

¹ University Hospital “G. Rodolico - San Marco”, Neurosurgery, Catania, Italy

Introduction: Treatment of adult degenerative scoliosis represents one of the main challenges in contemporary spinal surgery, also in view of the epidemiological trend of population ageing. Traditional open surgery has characteristics, such as large surgical incision, usually longer surgical times, significant damage to the paravertebral muscles, considerable blood loss, intense post-operative pain with consequent delay in mobilization, which are poorly suited to an increasingly aged population usually affected by comorbidities, which can represent absolute contraindications to surgical interventions of this type. The use of modern minimally invasive surgical techniques with combined anterolateral and posterior approaches allows to considerably reduce risks and complications related to traditional open surgery, while still allowing satisfactory correction of the deformity to be achieved. Material and Methods: We retrospectively retrieved 50 patients (14 male and 36 female, mean age 64.8) treated for adult degenerative scoliosis with a double minimally invasive antero-lateral (XLIF) and posterior approach (MIS fixation ± TLIF), with intraoperative CT control and, in some cases, neuronavigation. All patients were studied preoperatively with whole spine X-ray in standing position (AP and LL), lateral bending and L/S dynamic views, MRI and spine CT; preoperative VAS and ODI were measured. Cobb angles were measured for the scoliotic curve and the spinopelvic parameters (PT, PI, SS, LL, L4-S1L) were analysed for sagittal alignment. Results: For each patient, data of sagittal and coronal imbalance were obtained as well as number and location of vertebral levels treated with anterolateral and posterior approaches; levels of posterior MIS fixation were recorded. Perioperative complications, intraoperative blood loss, blood transfusions, average hospital stay and clinical outcome at 1, 6 and 12 months were analyzed. Radiological outcome was evaluated by comparing whole spine pre- and post-operative X-rays (AP-LL) with coronal (Cobb angles) and sagittal alignment (PT, PI, SS, LL, L4-S1L). One patient suffered from early implant dislocation, which necessitated revision and lengthening of the system; in one patient a screw needed repositioning; 2 patients developed wound dehiscence requiring surgical revision. 6 patients suffered from post-surgical anemia requiring blood transfusion. Mean postoperative hospital stay was 6.3 days. The difference between pre- and last-follow-up VAS is statistically significant (7.545 vs 4.454, T test p < 0.005) as well as that between pre- and post-operative ODI (75.263 vs 44.368, T test p < 0.005). The average preoperative Cobb angle of the major scoliotic curve was 18.68° ± 8.47, while 5.27° ± 3.27 postoperative, with a variation of 71.7% (p < 0.001). The calculated preoperative mean lumbar lordosis (LL) was 37.9° ± 14.2, while 42.9° ± 10.5 postoperative (p = 0.06). Conclusion: The mini-invasive/mini-open hybrid treatment with double anterolateral and posterior approach of adult degenerative scoliosis has been shown to be noninferior to traditional open treatment in terms of radiological outcome, satisfactory degree of correction of the deformity both on coronal and sagittal. Furthermore, in terms of clinical outcome it has proved to be a valid and effective alternative to open surgery, being burdened by a lower rate of peri and post-operative complications.

ID: 800

RF326: What factors influence radiographic aggravation in ankylosing spondylitis patients?: An analysis using Roussouly Classification and GAP score

Yoon Jae Cho ¹ , Jung Sub Lee ¹ , Tae Sik Goh ¹ , Hansol Kim ¹ , Minjun Choi ¹

¹ Pusan National University Hospital, Department of Orthopaedic Surgery, Busan, South Korea

Introduction: Roussouly classification and GAP score are widely used tools for categorizing spinal alignment. However, there are no reports on the prevalence of specific types among ankylosing spondylitis (AS) patients and the correlation between these classifications and the disease. This study aims to investigate the distribution of Roussouly types and GAP scores in AS patients and examine their relationship with disease characteristics. Materials and Methods: We conducted a retrospective analysis of 330 patients diagnosed with AS at a single center from 2010 to 2024. Data collected included demographic characteristics, spinopelvic parameters, sagittal vertical axis (SVA), Roussouly classification, and GAP score. We analyzed the distribution of each variable in AS patients and conducted statistical analysis related to radiological progression for 125 individuals who were available for radiological follow-up for more than one year. Results: The average age of the study population was 41.1 ± 16.8 years with a follow-up period of 1.92 ± 3.17 years, consisting of 110 females and 220 males. Among all patients, the most common Roussouly type was Type 3, followed by Types 2 and 4, with Type 1 being the least common. Out of the 125 patients with radiographic follow-up, 89 showed no radiologic progression, whereas 36 demonstrated progression. The Roussouly classification distribution indicated significant differences between the groups, with Type 1 being more prevalent in the progression group (36.1% vs. 6.7%, p = 0.002). Patients with radiologic progression had significantly higher GAP scores (5.4 ± 4.5 vs. 1.8 ± 3.1, p < 0.001), increased SVA (52.5 ± 50.2 mm vs. -1.1 ± 28.8 mm, p < 0.001), and different spinopelvic parameters including lower lumbar lordosis (42.8 ± 17.3° vs. 51.1 ± 13.9°, p = 0.015), higher pelvic tilt (21.6 ± 8.7° vs. 13.4 ± 8.5°, p < 0.001), and lower sacral slope (29.8 ± 10.6° vs. 36.4 ± 8.9°, p = 0.002). Conclusion: The distribution of the Roussouly classification among the entire population of patients with AS matches the frequency distribution in the normal population. However, it was noted that the proportion of patients with radiographic progression is significantly higher in Type 1. Additionally, Higher GAP scores and increased sagittal vertical axis values are indicative of disease progression. Understanding these correlations can aid in the early identification and management of patients at risk for radiographic progression.

ID: 752

RF327: Use of early recovery after surgery protocols in adult spinal deformity with meta-analysis - are they effective?

Ahmed Hassan ^1,2 , Mohamed Hassanin ¹ , Elie Najjar ¹ , Nasir Quraishi ¹

¹ Queen’s Medical Centre, Nottingham University Hospitals NHS Trust, Centre for Spinal Studies and Surgery, Nottingham, United Kingdom,

² Assiut University Medical School, Orthopedics and Trauma Surgery, Assiut, Egypt

Introduction: Surgery for Adult Spinal deformity (ASD) can improve functional outcomes for patients, but the complication rates remain high. Enhanced Recovery after Surgery (ERAS) was first described in 1997 for colorectal surgery as a perioperative management pathway that reduces surgical stress response, aiming towards reducing the length of hospital stay and the overall incidence of complications. Since then, its use has gradually expanded to include spinal surgery. The main aim of our study was to assess all the available literature on the use of ERAS protocols in ASD and to evaluate its efficacy with regard to reducing blood loss (EBL), hospital stay, post-operative ambulation and complication/revision surgery. Material and Methods: A systematic review of the English-language literature was conducted using PubMed, Web of Science, and Cochrane databases up to June 2024, adhering to the PRISMA guidelines using free text forms and Boolean operators. Studies that included less than 3 fused segments or secondary causes of spinal deformity (e.g. infection, trauma or tumours) were excluded. The Risk of Bias (ROB) was assessed using the Joanna Briggs Institute (JBI) tool. Descriptive statistics were reported for all variables. Meta-analysis was conducted using Review Manager 5.5 software. The odds ratio (OR) was used to express the dichotomous data and the mean difference (MD) for continuous data. The random effect model was used, and the effect size was visualised in Forest plots. A p-value ≤ 0.05 was considered to declare statistical significance. Heterogeneity was assessed using the I2 test. Results: Out of the 65 articles initially identified, 5 were finally included in the study (all retrospective Level III) with all studies being eligible for meta-analysis. All of the studies showed a low risk of bias. The ERAS protocol was applied to 261 patients compared to 224 patients for the conventional pathway. No significant differences were observed in patients` demographics or baseline characteristics between the two groups. The meta-analysis showed statistically significant differences for EBL, length of hospital stay and post-operative ambulation, favouring the ERAS group (z = 2.03, p = 0.04, z = 3.39, p < 0.0007 and z = 3.94, p < 0.0001, respectively). However, there was no statistical significance between the two groups regarding complications (z = 1.75, p = 0.08) or revision surgery (z = 0.45, p = 0.65). Conclusion: The results of our study support the implementation of the ERAS protocol as a part of the surgical management of ASD to reduce EBL, hospital stay and earlier post-operative ambulation, but not complication rates or revision surgery. ERAS recommendations from the included studies are also discussed. However, our recommendation is restricted by the limited literature as all available studies are non-randomized retrospective studies with a small sample size, in addition to the lack of a standardized ERAS protocol across all study sites. Large randomised studies with uniformly reported assessment tools are required to reach more robust evidence.

ID: 88

RF328: Stand-alone extreme lateral interbody fusion (stand-alone XLIF) to treat radicular symptoms in patients with lumbar degenerative scoliosis: a monocentric observational study

Carolin Albrecht ¹ , Vicki Butenschön ¹ , Bernhard Meyer ¹ , Maximilian Schwendner ²

¹ Technical University Munich, Klinikum Rechts der Isar, Neurosurgery, Munich, Germany,

² University Hospital Heidelberg, Heidelberg, Germany

Introduction: Extreme lateral interbody fusion (XLIF) is a widely used technique for treating scoliosis and spondylolisthesis after a posterior fixation for spinal fusion. However, stand-alone XLIF may present an intermediate surgical strategy for primarily radicular symptoms for neuroforaminal or spinal canal stenosis in cases of severe degenerative coronal imbalance to avoid extensive posterior dorsal fixation and correction procedures. Therefore, this study aimed to evaluate the efficacy of treating radicular symptoms in degenerative scoliotic patients who underwent stand-alone XLIF without posterior instrumentation. Material and Methods: We performed a retrospective analysis of 21 patients who underwent stand-alone XLIF at our level 1 spine center between 2021 and 2024 for degenerative neuroforaminal stenosis or central canal stenosis due to thoracolumbar scoliosis and/or listhesis with coronal deformity. Post-operative outcomes were assessed regarding symptom relief, the need for revision surgery with posterior instrumentation, and post-operative radiological features such as restoration of foraminal height. Additionally, length of hospital stay, operative time, and blood loss were analyzed. We correlated initial diagnosis and number of heights fused with success rate to find predictive factors for good outcomes. Results: Patients' ages ranged from 65 to 86 years, with a median of 76 years; 48% were male and 52% female. Stand-alone XLIF was primarily indicated for adult degenerative scoliosis with neuroforaminal or central canal stenosis (67%) and spondylolisthesis in 14% of cases, including one ALIF. Most patients (43%) underwent single-level lateral fusion, while the maximum number of instrumented levels was three (29%). Of the 21 patients, 67% had previously unsuccessful lumbar decompression, and 9.5% had prior instrumentation at adjacent levels. Significant relief of radicular symptoms was reported in 52% of patients after stand-alone XLIF through indirect decompression. Additional dorsal direct decompression was performed in 28.6% of cases. Only four patients (19%) required secondary dorsal instrumentation and deformity correction due to persistent symptoms. Postoperative complications included retroperitoneal hematoma in 9.5% of patients and cage dislocation in 5%. Conclusion: Overall, 81% of patients experienced sufficient pain relief following stand-alone XLIF without posterior deformity correction. Stand-alone XLIF effectively addresses neuroforaminal stenosis through indirect decompression due to cage placement, promoting spinal alignment and secondary fusion. Additionally, secondary dorsal decompression for central spinal canal stenosis has been successful as a subsequent procedure, mitigating the need for extensive corrective spondylodesis in degenerative coronal scoliosis. While one out of five patients did require secondary dorsal instrumentation, our results demonstrate that stand-alone XLIF may present a viable treatment option for patients with degenerative scoliosis suffering from radicular symptoms or central canal stenosis.

ID: 534

RF329: Dental composite offers comparable or greater pullout and shear strength to lateral mass screw fixation in a human cadaveric model

Javier Castro ¹ , James Mok ¹ , Karl Bruckman ¹ , Calvin Chan ¹ , Anna Karnowska ¹ , Harsh Wadhwa ¹ , Olivia Okoli ¹ , Jayme Koltsov ¹ , Serena Hu ¹

¹ Stanford University School of Medicine, Stanford, United States

Introduction: Lateral mass screw fixation is the common method of fixation for instrumented posterior fusion of the subaxial cervical spine. While screws have established efficacy, dental composite material applied to the bony surface may be a promising alternative, offering potential advantages such as ease of application, size, and avoidance of screw loosening, malposition, or fracture. Material and Methods: 20 fresh frozen human cadaveric subaxial cervical vertebrae were collected and prepared for biomechanical testing. In each vertebra, one side underwent lateral mass screw fixation and the contralateral side underwent composite fixation. On the screw side, a 12x3.5 mm lateral mass screw was inserted using standard free hand technique (Ahn) by a spine surgeon. For the dental composite side, the lamina were treated with etching acid solution and dental bonding agent over a 10mm diameter area before an orthodontic metal bracket was attached using dental composite. Specimens were then fixed to a material testing machine (Instron E10000). 9 randomly chosen specimens in each group were subjected to an axial load to failure (pull-out) test, where the load was perpendicular to the vertebral surface. The remaining specimens were subjected to cyclical testing, where the load was applied cranially (shear) relative to each vertebrae and gradually increased with each cycle until failure occurred. Statistical analysis of the final ultimate loads was performed with a significance level set at p < .05. Results: Under axial load (pull-out), the dental composite group (203.4 ± 43.4N) showed significantly higher ultimate load than the screw group (127.7 ± 21.2N) (p < 0.001). The predominant failure mode under axial load was the composite cleanly pulling off the cortical bone surface whereas the screw pulled through the cancellous and cortical bone. In cyclical testing, the ultimate shear load between lateral mass screws (173.6 ± 65.5N) and composite materials (163.7 ± 48.4N) in human cadaveric bone was not significantly different (p = 0.7). The predominant failure mechanism observed in both fixation methods under shear loading was fracture distant from the fixation site, indicating robust fixation integrity despite material differences. Conclusion: Dental composite has similar shear strength and greater pullout strength compared to lateral mass screws. Composite fixation may serve as viable alternatives to traditional lateral mass screws in specific clinical scenarios. Dental composite may offer an alternative method of fixation for instrumented subaxial cervical spine fusion with similar resistance to shear load and greater pullout strength.

ID: 2619

RF330: Impact of minimally invasive lateral versus open posterior spinal surgery on spinopelvic parameters in adult spinal deformity

Puya Alikhani ¹ , Bryan Clampitt ² , Chloe Chose ² , Kiran Kittur ² , Petra Allen ² , Molly Monsour ² , Jay I. Kumar ¹ , Diego Soto Rubio ¹ , Cesar Carballo ¹

¹ Department of Neurosurgery and Brain Repair, University of South Florida, Morsani College of Medicine, Tampa, United States,

² USF Health Morsani College of Medicine, Tampa, United States

Introduction: Minimally invasive spine surgery (MIS) has emerged as a promising advancement in treating adult spinal deformity (ASD), aiming to reduce morbidity and complications compared to traditional open approaches. Understanding spinopelvic parameters is crucial for predicting surgical outcomes and patient suitability. Material and Methods: A retrospective review spanning 2016-2023 included all ASD surgeries at our tertiary care center. MIS was defined as lateral interbody fusion and percutaneous screw fixation, while open techniques involved full exposure pedicle screw and rod placement. Procedures addressed multilevel fusions for scoliosis and/or kyphosis correction with uppermost instrumentation typically at L2 or higher and lower instrumentation at S1 or the pelvis. Sagittal spinopelvic parameters were assessed using Surgimap, with postoperative mismatch from the Schwab angle and age-adjusted ideals calculated. Statistical analysis utilized SPSS. Results: Data from 265 patients revealed 36 (13.6%) underwent MIS procedures. Preoperative spinopelvic parameters were comparable between MIS and open surgeries. MIS procedures involved fewer fused levels (6.3 ± 1.6 vs. 8.5 ± 3.3, p < .05). Preoperative pelvic incidence-lumbar lordosis (PI-LL) mismatch tended to be lower in MIS (mean difference 4.6, 95% CI -0.8-10.1, p = 0.095), with significantly higher lumbar lordosis (LL) (mean difference -5.4, 95% CI -10.0- -0.84, p = 0.021). MIS achieved significantly less improvement in sagittal vertical axis (SVA) compared to open (ΔSVA 2.6 ± 1.3 mm vs. 4.7 ± 3.5 mm; p < .05). Differences in LL correction (mean difference 3.6, 95% CI 0.62-6.6, p = 0.019) and SVA (mean difference 2.1 mm, 95% CI 1.4-2.7 mm, p = 0.0) favored open approaches, indicating greater correction capability compared to MIS. MIS also exhibited larger mismatches from Schwab SVA (mean difference -8.9 mm, 95% CI -16.4- -1.5 mm, p = 0.02) and age-adjusted ideal SVA (mean difference -7.8 mm, 95% CI -16.8-1.2 mm, p = 0.087). Conclusion: In our cohort, MIS Lateral procedures showed less optimal adjustment of SVA and LL compared to open approaches, potentially attributed to limited osteotomy capabilities. Other spinopelvic parameters demonstrated similar outcomes between MIS and open approaches, suggesting nuanced considerations in surgical planning for ASD correction.

ID: 2858

RF331: Pre-operative pelvic incident associated with changes in distal lumbar lordosis and L1PA following low thoracic to the pelvis fusions for adult spinal deformity

Christopher J. Nielsen ¹ , Fatemeh Alavi ² , Francois Dantas ² , Stephen Lewis ¹ , Raja Rampersaud ¹

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

² Toronto Western Hospital, University Health Network, Toronto, Canada

Introduction: Sagittal alignment of the spine, as a modifiable risk factor for mechanical complications such as proximal junctional kyphosis (PJK), gained attention in the field of spinal deformity surgery. Recent research highlighted the importance of segmental lumbar lordosis restoration in sagittal alignment. We hypothesized that preoperative patient sagittal alignment parameters may impact achieving the desired postoperative distal lumbar lordosis (DLL > 30°) and L1PA. Material and Methods: 91 ASD patients (mean age 66.7 ± 10.8 years, 65.9% females) who underwent fusion surgery from the distal thoracic spine (upper-instrumented vertebra (UIV) from T9 to T12) to the pelvis in a single institution with minimum 1-year follow-up were retrospectively reviewed. The spinopelvic parameters were measured on preoperative and immediate postoperative images. Distal and proximal lordosis were represented as DLL and PLL, defined as L4-S1 and L1-L4 Cobb angles, respectively. The patients were stratified into two groups: postoperative DLL > 30º and DLL < 30º. PLL, LL, L1PA, and PT were compared between the two groups. Moreover, the values were compared between PJK and NPJK patients in each group. Results: 27% of patients had high DLL postoperatively. Among those, 44% developed PJK. There was no significant difference between the rate of PJK in high and low DLL groups (44% vs. 47%). Pelvic incidence (PI) was higher in the high DLL group (53° ± 13° vs. 43° ± 9°, p-value 0.002). However, there was no significant difference in PI between PJK and NPJK groups in each DLL group. In general, the mean post-to-pre increase in DLL was higher in the high postop DLL than low DLL group (5° vs. 1°). High postoperative DLL group had significantly more LL and DLL but same PLL preoperatively (DLL preop: 30° ± 13° vs. 21° ± 9°, p-value 0.004, LL_pre: 33° ± 23° vs. 21.6° ± 15°, p-value 0.02). Although the mean value of postoperative PLL was the same in both groups, LL was significantly higher in high DLL group (44° ± 12° vs. 32° ± 8°, p-value < 0.001). PJK group on average had kyphotic PLL preoperatively and experienced severe post-to-pre PLL changes compared to NPJK patients (12° vs. 7° changes), which can be one of the PJK risk factors. In patients with low postop DLL, the UIV distance to a line connecting T1 to the femoral head was significantly higher in PJK compared to NPJK group pre and postoperatively (p-values 0.02 and < 0.001). Conclusion: Correcting distal lumbar lordosis to greater than 30 degrees was more common in patients with higher pre-operative distal lordosis and pelvic incidence. Greater DLL was associated with greater change in L1PA. However, our research could not recognize any difference in the rate of PJK between groups, pre-operative proximal lumbar kyphosis and greater magnitude of change in PLL was significant for the development of PJK in the low DLL group.

ID: 298

RF332: Efficacy and surgical outcomes of posterior apical spinal osteotomy in thoracic/thoracolumbar/lumbar kyphoscoliosis in dystrophic curves of neurofibromatosis type 1

Jenil Patel ^1,2 , Ashwinkumar Khandge ³

¹ Bombay Hospital and Research Institute, Spine Surgery, Mumbai, India,

² Lilavati Hospital and Medical Institute, Spine Surgery, Mumbai, India,

³ D y Patil Medical College and Hospital, Pune, India

Introduction: Kyphoscoliosis (10-60%) most common deformity seen in patients of NF1. These dystrophic curves have a severe deformity often require surgical intervention. Various procedures which have been evaluated and studied with no obvious consensus which are also associated with higher rate of morbidity hence, the objective of this study was to evaluate the clinical and radiological outcomes of performing an apical spinal osteotomy in cases with thoracic/ thoracolumbar/ lumbar kyphoscoliosis in dystrophic curves in NF-1. Materials and Methods: A retrospective analysis of prospective collected data involving 21 children with dystrophic NF-1 curves operated with apical spine osteotomy at a single tertiary care centre from Nov 2009 - June 2017. The efficacy of ASO to correct the coronal and sagittal deformities was assessed. The clinical outcome (VAS, ODI, and Frankel grade) and radiological outcome (Cobb angle correction, fusion, complications) were evaluated. Results: 21 patients (11 males,10 females) with mean age of surgery 9 .33 yrs. Mean kyphotic Cobbs angle improved from 98.33 degree to 36.52 degree. The mean sagittal Vertical Axis (SVA) also improved significantly from 7.40 cms to 4.21 cms along with significant improvement in VAS and ODI scores. Conclusion: In this study, the authors described a technique of posterior approach single-level apical spinal osteotomy (ASO) for the treatment of severe dystrophic NF-1 curves. The technique can be performed in children with mild to moderate curves with good clinico-radiological outcomes and satisfactory correction rates.

Keywords: Posterior Apical spinal osteotomy, Kypho scoliosis, NF1, Deformity correction

ID: 528

RF333: Surgical management of lateral thoracic spinal cord herniation

Olivia Gilbert ¹ , Michael Galgano ¹

¹ University of North Carolina, Neurosurgery, Chapel Hill, NC, United States

Introduction: Spinal cord herniation (SCH) is an exquisitely unique pathology that is rarely encountered in an academic practice. Since it was first described in 1974, there have been less than 200 cases in the existing literature. Further, these cases are almost always located at the anterior thoracic spine levels, but some dorsal cervical SCHs have been described. One French case report describes an isolated lateral thoracic spinal cord herniation and its surgical management. These patients classically present with chronically progressive myelopathy, Brown-Séquard syndrome, or isolated neurological deficits including bladder/bowel incontinence. Material and Methods: Here we detail the second reported case in the world of a patient with lateral thoracic spinal cord herniation including an intracavitary meningeal diverticula, with novel illustrations, intraoperative photos, and a brief 2D operative video to supplement the presentation of his delicate surgical management. A previously healthy 23-year-old male presented with progressive loss of sensation, motor function, and proprioception in his left leg for years but with rapid deterioration over 9 months. His neurological exam was significant for thoracic myelopathy with long tract signs and left leg weakness. MRI and CT myelogram demonstrated a large left-sided dural diverticulum at T3-4 with spinal cord herniation extending out the neural foramen. The cord was severely stretched and tethered to the wall of the diverticulum, with a small adjacent lipoma. There was a syrinx spanning above and below the herniation, as well as a thoracic S-shaped scoliotic deformity. Surgical intervention was pursued to prevent further progression of his symptomatology. Results: Patient underwent T2-4 laminectomies and left T3-4 facetectomies, partial pediculectomies, and transverse process removal for intradural spinal cord detethering and reduction of the lateral herniation. Intraoperatively the cord within the dural diverticulum appeared dysplastic, hypervascular, and severely tethered at several points within the defect. Spinal ultrasound was utilized to confirm normal-appearing cord at the cranial and caudal extent of the exposure. A T-shaped dural opening was made to obtain optimal exposure to the most lateral portion of the herniated cord, noting the diverticulum itself extended beyond the cord herniation towards the pleura and aorta. Dentate ligaments were divided, and thick adhesions were released to detether the cord circumferentially. There was a transient reduction in left leg motor evoked potentials during reduction that resolved without postoperative clinical correlation. Alloderm was placed within the diverticulum laterally, and the contralateral dentate ligaments were sutured to the medial dura as secondary means of preventing reherniation and retethering. A lumbar drain was placed for 5 days to promote wound healing. At three months postoperatively, the patient has increased sensation in his left leg with stable ambulation. His scoliotic deformity was not corrected during surgery and remained stable on postoperative x-rays. Conclusion: SCH are not only extremely rare, but the lateral herniation described here represents only the second such case in the existing literature. The complexity of managing such cases, given the paucity of available data and intricate nature of the pathology, underscores the need for heightened awareness and discussion within the global spine community.

ID: 1823

RF334: Comparing functional outcomes of coronally balanced vs. unbalanced scoliosis patients

Isador Lieberman ¹ , Kyle Robinson ² , Bethany Wilson ² , Sara McMahan ²

¹ Texas Back Institute, Frisco, United States, ² Texas Back Institute, Plano, United States

Introduction: Adult spinal deformity (ASD) is a complex condition that can impact quality of life by causing pain and restricting mobility, leading to functional deficits. Deformities that span across a range of vertebral bodies can cause misalignment in both the sagittal and coronal directions. Although the impact of sagittal misalignment on gait and functional balance has been extensively studied, coronal misalignment has received comparatively less attention. This study aims to isolate the impact of coronal imbalance on functional outcomes by comparing functional measures between coronally balanced vs. unbalanced ASD patients, as well as how their functional outcomes compare to asymptomatic controls. Material and Methods: This was a preliminary analysis of a prospective, non-randomized study involving presurgical ASD patients and asymptomatic controls. ASD subjects were divided into the following two cohorts based on radiographic measurements: 1) Balanced (CVA < 20 mm) and 2) Unbalanced (CVA ≥ 20 mm). Patients were evaluated at a single timepoint, approximately 1 week before surgery (P0). Each subject was assessed using the Visual Analog Scale for Pain and the Oswestry Disability Index, and functional status through three 10-meter over-ground walking tests. Kinematic motion data and kinetic ground reaction force data were collected during all activities using three-dimensional motion tracking and force plates. Results: This study included 11 Balanced ASD subjects (9F/2M, Age: 50.8 ± 17.1, BMI: 28.1 ± 6.4), 7 Unbalanced ASD subjects (4F/3M, Age: 55.6 ± 17.9, BMI: 25.7 ± 5.9), and 18 asymptomatic controls (5M/13F, Age: 51.9 ± 16.4, BMI: 25.5 ± 3.8). Patients in both ASD cohorts reported comparable pain and disability scores with no significant differences between groups (all p > 0.05). No significant difference was uncovered when comparing the Balanced vs. Unbalanced ASD groups regarding spatiotemporal variables or balance measures (all p > 0.05). However, the Unbalanced ASD group displayed significantly reduced temporal gait measures, including walking speed and cadence, when compared to asymptomatic controls (p < 0.05). Conversely, the Balanced ASD group demonstrated reduced spatial measures during gait when compared to asymptomatic control, including step length and stride length, where p < 0.05. Additionally, when compared to asymptomatic controls, both symptomatic groups displayed an increased range of motion in the ankles and knees (p < 0.05). Lastly, unbalanced ASD patients exhibited a more exaggerated lateral motion while walking compared to coronally balanced ASD patients, highlighted by the elevated maximum displacement of the torso during gait (p < 0.05). Conclusion: Both the Unbalanced and Balanced ASD groups displayed various functional deficits when compared to asymptomatic controls. Although no significance was found between symptomatic groups regarding spatiotemporal variables and balance, the two groups displayed distinct independent differences from asymptomatic controls during gait. Unbalanced ASD patients demonstrated a greater lateral range of motion during gait compared to both the Balanced ASD cohort and asymptomatic controls. These findings may suggest previously undiscovered nuances in the compensatory mechanisms used by ASD patients with different deformity classifications and severity, such as those with significant coronal misalignment. To increase the power of this study, a larger sample size should be considered in future analyses.

ID: 450

RF335: Does the new Lenke modular radiographic classification of adult idiopathic scoliosis (AdIS) reliably dictate preferred treatment?

Christopher Mikhail ¹ , Fthimnir Hassan ² , Andrew Platt ³ , Stephen Stephan ⁴ , Gerard Marciano ² , Jose Sarmiento ⁵ , Lawrence Lenke ²

¹ Cedar Sinai Medical Center, Los Angeles, United States,

² Columbia University Irving Medical Center, New York, United States,

³ Loma Linda University Health, Loma Linda, United States,

⁴ Scripps Health, La Jolla, United States,

⁵ Cleveland Clinic, Weston, United States

Introduction: In attempt to both classify AdIS and help predict treatment, Lin, Lenke et al. published a modification of the original triad modular Lenke AIS classification which includes 6 (same) curve types, Lumbosacral and Global Alignment modifiers. The purpose of this study is to assess if this modular classification can accurately recommend fusion regions of AdIS. Methods: This was a retrospective study of AdIS patients who underwent corrective spine surgery. Patient demographics, periop data, and radiographic parameters were collected at baseline. Patients were then classified based on the new modular Lenke AdIS classification. Compliance with recommended treatment was then assessed on postop xrays with respect to whether structural regions were included in the fusion and nonstructural regions were not. Radiographic assessment of moderate to severe stenosis on lumbar MRI was added to the classification and reassessed if this improved compliance. Results: 153 patients were included [Type (T) 1 (30), T-2 (15), T-3 (24), T-4 (12), T-5 (39), T-6 (33)] [127 = F (83.6%)]. Median age was 45yrs, 13 patients (8.6%) had 3COs, and pelvic fixation was done on 82 patients (53.6%). Overall adherence of the original classification was 58.2%. When applying a lumbar MRI modifier, adherence increased to 62.7% (p = 0.4131). Treatment adherence was lowest in T-1 (73.3%), 2 (66.7%), and 5 (30.8%) curves. Adherence was at its highest in T-3 (95.8%), 4 (91.7%), 6 (90.9%) curves. When excluding T-5 curves, treatment adherence increased from 62.7% to 75.4% (p = 0.0276). The vast majority of Type 5 non-adherence was due to inclusion of a “nonstructural” Main Thoracic curve due to other clinical criteria such as shoulder alignment. A structural LS curve resulted in pelvic fixation in 91.2% of patients. On the contrary, a nonstructural curve resulted in no pelvic fixation in 68.8% of patients. All patients with lumbar stenosis on MRI were decompressed and instrumented to the pelvis. Conclusions: The new AdIS classification system had fairly good treatment recommendations for all curves (75.4%) except for Type 5 (only 31%) by this modular adaptation of the AIS system. The addition of a lumbar stenosis modifier on MRI predicted pelvic fixation with 100% accuracy.

ID: 2487

RF336: Adult degenerative scoliosis treated with stand alone OLIF/XLIF: clinical and radiological outcomes in patients who refused posterior surgery

Antonino Raco ¹ , Michele Dughiero ² , Nicolo Norri ² , Massimo Miscusi ² , Luca Ricciardi ¹ , Sokol Trungu ³ , Stefano Forcato ³

¹ La Sapienza, Rome, Italy,

² University of Ferrara, Ferrara, Italy,

³ Department of Neurosurgery Pia Fondazione di Culto e Religione Cardinal G. Panico, Tricase, Italy

Introduction: The staged approach for treating adult degenerative scoliosis has become quite common. In our clinical practice, several patients, after the first-stage anterior procedure, refused posterior stabilization due to a satisfactory health condition. The study aims to analyze the data and outcomes of these patients treated with stand-alone minimally invasive technique. Material and Methods: A retrospective analysis was conducted on patients treated for scoliosis or kyphoscoliosis by our surgical team at two different hospital centers over the past ten years. Those who had prior spinal surgeries were excluded from the study, as well as those treated for single-level discopathy. For each patient, preoperative and postoperative clinical and radiological data were collected and analyzed, including Short Form Health Survey 36 (SF-36), Oswestry Disability Index (ODI), Visual Analogue Scale (VAS), radiographic measurements of spinal alignment and complication rates. A minimum follow-up of 18 months was evaluated. Results: A total of 18 patients were selected for the study, with a mean age of 68 (± 7). 12 patients were treated using the XLIF stand-alone technique, while the remaining 6 underwent OLIF stand-alone. 9 of them were treated at two levels, 7 at three levels, and 2 at four levels, for a total of 47 levels treated. The SVA was less than 25 mm in all patients except one, which was 28 mm preoperatively and 20 mm postoperatively, indicating that none had sagittal imbalance postoperatively. All patients showed an improvement in VAS, ODI, and SF-36 scores. The mean postoperative lumbar lordosis (p < 0.01) and the Pelvic index – lumbar lordosis (p < 0.02) significantly improved compared to the preoperative values. The rate of postoperative complications is comparable to that reported in other studies. Conclusion: Stand-alone OLIF and XLIF are two surgical options that can be considered in adult degenerative scoliosis in selected patients, particularly those without major deformities in the sagittal plane. These procedures can provide significant clinical benefits even if they don't completely correct the coronal plane deformity.

ID: 2302

RF337: Evaluation of mechanical complications in adult spine deformity cohort

Avionna Baldwin ¹ , Zodina Beiene ² , Aboubacar Wague ¹ , Ashraf El Naga ¹ , David Gendelberg ¹ , Sigurd Berven ¹

¹ University of California, San Francisco, Orthopedic Surgery, San Francisco, United States,

² Orthopedic Trauma Institute, San Francisco, United States

Introduction: Adult spine deformity patients are at a higher risk of complications due to the complex nature of the surgery in an older patient population. Given this increased risk of complications, it is important to identify modifiable risk factors. While previous studies have identified osteoporosis as a risk factor for mechanical complications in spine surgery, the majority did not utilize the gold standard for osteoporosis diagnosis: Dual-Energy X-ray Absorptiometry (DXA). The purpose of this study was to evaluate the correlation between osteoporosis (as defined by DXA scans) and mechanical complications in an adult spine deformity cohort. Methods: Retrospective study design of adult spine deformity patients 45 and older undergoing at least six levels of fusion between 2016-2018. Electronic medical record was used to collect patient demographics and perioperative data. The four cohorts (osteoporosis, osteopenia, normal DXA, and no DXA (ND)) were compared using statistical analysis and significant variables identified (p value < 0.05). Multivariable logistic regression was performed to identify any independent associations while accounting for potential confounders. Results: 586 total patients had osteoporosis 77 (13.1%), osteopenia 156 (26.6%), normal DXA91 (15.5%), and ND 262 (44.7%). Age (p < 0.0001), sex (p < 0.0001), service (p < 0.0001), region of surgery (p < 0.0001), approach (p = 0.0057), and number of levels (p < 0.0001). was significantly different between groups. There were significantly more females in the osteoporosis (65, 18.4%) (p < 0.0001) and osteopenia (114, 32.2%) (p < 0.0013) groups, whereas more males predominated in the ND group (141, 60.8%) (p < 0.0001) on post-hoc analysis. The ND group was treated by the orthopedics service (144, 58.1%) (p < 0.0001), compared to the normal DXA treated by the neurosurgery service (69, 20.6%) (p < 0.0011). Thoracic-sacral surgery was associated with the osteopenia group (119, 31.4%) (p < 0.0112) and cervical surgery was associated with ND group (81, 70.4%) (p < 0.0001). Surgery on 6-11 levels was significantly associated the ND group (232, 50.5%) (p < 0.0001) versus 12 or more levels which was associated with the osteoporosis group (34, 26.8%) (p < 0.0001). The circumferential approach was significantly associated with osteopenia (p = 0.0173) and the posterior approach was associated with the ND group (p = 0.0381). There were proportionally more complications in the groups with osteopenia (56, 33.5%) and osteoporosis (24, 14.4%) compared to no complications (100, 23.9%; 53, 12.6%) although the difference between groups trended toward significance (p = 0.0702). There was no significant difference between groups in terms of revisions. Conclusion: In this small cohort, while there was no significant difference in complication rates, a proportionally greater number of patients with mechanical complications had abnormal scans indicating osteoporosis or osteopenia. Previous work surrounding osteoporosis and mechanical complications has variability in the definition of osteoporosis, while our work uses DXA scans to define osteoporosis/osteopenia. The significant differences in terms of age, sex, service, region of surgery, approach, and number of levels among those with diagnosed osteoporosis and osteopenia compared to normal and unknown groups. These differences suggest screening cannot be overlooked in those with an unknown status. This study further underscores the importance for preoperative evaluation and treatment in high-risk individuals to reduce complications rates.

ID: 2219

RF338: Upper instrumented vertebrae selection based on the first coronal reverse vertebrae in degenerative lumbar scoliosis without stable vertebra

Weishi Li ¹ , Zhuoran Sun ¹ , Xiang Yu Hou ¹

¹Peking University Third Hospital, Orthopedics, Beijing, China

Introduction: A lot of patients with degenerative lumbar scoliosis (DLS) lack an actual stable vertebra (SV), for whom selection of the upper instrumented vertebra (UIV) using plain radiographs can be difficult. This study aimed to describe the presence of SV in patients with DLS, and to assess the viability of utilizing the first coronal reverse vertebra (FCRV) as a criterion for selecting the UIV in patients with DLS lacking SV. Material and Methods: We retrospectively analyzed 153 consecutive patients with DLS. FCRV was determined by measuring the bilateral Hounsfield units of the vertebrae on preoperative CT. Pre- and postoperative plain radiographs were examined for determination and classification of SV, evaluation of proximal adjacent segment degeneration (pASD), and other radiological measurements. Results: The patients with DLS could be classified into four types based on the presence of SV and the relationship between the vertebrae and the central sacral vertical line. Among all 153 patients, 42 (27.45%) patients did not have SV. They exhibited a significantly more cranial UIV level, longer fusion level, and larger coronal balance distance on average. Patients with UIV at or above (≤) FCRV had a significantly lower rate of pASD than those with UIV below FCRV, both in all 153 patients (9.4% vs. 24.6%, p = 0.011) and in the 42 patients without SV (6.7% vs. 33.3%, p = 0.046). No other parameters significantly affected the occurrence of pASD. Among the 42 patients without SV, five did not have neutral vertebra (NV). In the other 37 patients with NV, NV was significantly higher than FCRV, and there is no significant difference in pASD occurrence between UIV ≤ NV patients and UIV > NV patients, while the occurrence of pASD remains significantly lower in UIV ≤ FCRV patients than in UIV > FCRV patients (3.8% vs. 36.4%, p = 0.021). The numbers of patients developing pASD are both one in both UIV ≤ FCRV and UIV ≤ NV groups. Conclusion: Over 1/4 (27.45%) of the patients with DLS did not have SV. These patients often present with severe coronal imbalances and require extensive surgery. Selection of UIV at or above the FCRV can significantly reduce the risk of pASD in these patients. For this population, FCRV proves to be a superior selection criterion compared to NV.

RF20: MIS 2

ID: 2007

RF339: Construction of a nomogram of postoperative residual pain in percutaneous vertebroplasty for single-segment osteoporotic vertebral compression fractures

SI Chen ¹

¹ Banan Hospital of Chongqing Medical University, Orthopaedics, Chongqing, China

Introduction: Percutaneous vertebroplasty (PVP) has become the mainstream treatment for patients with osteoporotic vertebral compression fractures (OVCFs). However, there are still some patients with residual pain after PVP, which seriously affects the efficacy of surgery. This study aims to analyze the independent risk factors for residual pain after PVP for single-segment OVCFs and to construct a nomogram prediction model with these factors. Material and Methods: Patients with single-segment OVCFs treated with PVP at Banan Hospital of Chongqing Medical University between January 2021 and June 2023 were included, and patients were divided into remission and residual pain groups based on whether they scored ≥ 4 on the visual analogue scale at both 3 days and 1 month postoperatively. LASSO regression was used to screen independent predictors of residual pain after PVP for single-segment OVCFs, from which a nomogram model was constructed and converted into an online calculator. The model was evaluated for discrimination, calibration, and clinical applicability by means of area under the receiver operating characteristic curve (AUC), calibration curve analysis, and decision curve analysis (DCA). Finally, the model was externally validated in a validation cohort and internally validated using Bootstrap. Results: This study included 309 patients, 74 males and 235 females, aged (75.77 ± 8.30) years, including 280 in the remission group and 29 in the residual pain group. Degree of fracture, intervertebral vacuum cleft, lumbodorsal fasciitis, bone cement distribution, and facet joint violation were screened as independent predictors. The AUC of the model was 0.851 [95% CI (0.802-0.900)] and the external validation result was 0.836 [95% CI (0.787-0.885)]. Also, the calibration curves and DCA verified that the model had satisfactory practical consistency and clinical applicability. Conclusion: Degree of fracture, intervertebral vacuum cleft, lumbodorsal fasciitis, bone cement distribution, and facet joint violation were associated with residual pain after PVP treatment of single-segment OVCFs, and the model based on this has good predictive efficacy, which can provide some basis for clinical decision-making in patients with OVCFs.

ID: 2134

RF340: Hemilaminectomy versus laminectomy for spinal tumors: a systematic review and meta-analysis

Gabriel Piñeiro ¹ , Marcos Paulo de Oliveira ¹ , Pedro Henrique Sandes ¹ , Davi de Souza ¹ , Gabriel Nunes ¹ , Caio Trocoli ² , Roger Schmidt Brock ³ , Vinıcius Monteiro de Paula Guirado ³ , Danilo Gomes Quadros ⁴

¹ Federal University of Bahia, Salvador, Brazil,

² Bahiana School of Medicine, Salvador, Brazil,

³ University of São Paulo Medical School, Department of Neurology, Division of Neurosurgery, São Paulo, Brazil,

⁴ Núcleo Oscar Freire, Salvador, Brazil

Introduction: Hemilaminectomy is a less invasive surgical option than the laminectomy technique in spinal tumors, but it remains to be seen which method provides better results. Thus, we aimed to perform a meta-analysis comparing outcomes between both approaches. Material and Methods: We searched PubMed, EMBASE, and Web of Science for studies comparing hemilaminectomy to laminectomy patients who underwent spinal tumor resection until August 2024. Outcomes were total resection rate, neurological deterioration, postoperative complications, length of stay, operative time, and estimated blood loss. Statistical analysis was performed using the R software (version 4.4.1). Heterogeneity was assessed with I² statistics. Results: Twelve studies, were included in this systematic review. A total of 1047 patients were included, with 405 (38.68%) in the hemilaminectomy group and 642 (61.32%) in the laminectomy group. The mean patient age was 56.6 ± 7.5 years. The mean follow-up was 19.4 ± 15.3 months. Of the tumors, 44.8% were meningiomas, and 57.4% were located in the thoracic spine. The most common tumor locations in the spinal canal were intradural extramedullary, extradural, and intradural intramedullary, accounting for 777 (79.86%), 172 (17.68%), and 24 (2.47%) patients, respectively. With no statistical difference between hemilaminectomy and laminectomy in total resection rate achieved (RR 1.04, 95% CI: 0.98-1.11, I² = 38%), hemilaminectomy showed lower neurological deterioration (RR 0.53, 95% CI: 0.35-0.81, I² = 0%) and postoperative complications (RR 0.58, 95% CI: 0.39-0.86, I² = 12%). Furthermore, length of stay (MD -2.84 days, 95% CI: -4.85 to -0.84; I² = 90%), operative time (MD -26.44 min, 95% CI: -46.22 to -6.67; I² = 61%), and estimated blood loss (MD -120.89 mL, 95% CI: -183.61 to -58.17; I² = 81%) were significantly lower in hemilaminectomy. In a subgroup analysis removing patients with metastasis, hemilaminectomy still showed no difference in total resection rate (RR 1.04, 95% CI: 0.98-1.13; I² = 42%), less postoperative complications (RR 0.53, 95% CI: 0.30-0.95; I² = 31%), less length of stay (MD -3.78 days, 95% CI: -6.13 to -1.43; I² = 85%), and less blood loss (MD -133.36 mL, 95% CI: -180.00 to -87.71; I² = 14%). However, there was no difference in neurological deterioration (RR 0.53, 95% CI: 0.35-0.81; I² = 0%) and operative time (MD -25.15 min, 95% CI: -50.56 to 0.26; I² = 67%) between hemilaminectomy and laminectomy non-metastatic patients. Conclusion: Hemilaminectomy is associated with lower neurological deterioration, postoperative complications, operation time, length of stay, and estimated blood loss with no difference in total resection rate compared with laminectomy in spinal cord tumors. Therefore, our results might suggest that hemilaminectomy may be a more promising and safer alternative to laminectomy.

ID: 2077

RF341: Full endoscopic interlaminar resection of lumbar facet cyst with neurologic complication in a cohort of 52 cases: 10 years follow up

Suthavee Pangkanon ¹

¹ Bumrungrad International Hospital, Spine Institute, Bangkok, Thailand

Introduction: Facet joint cysts (FJCs) are a rare but significant cause of neurological symptoms in lumbar spinal degenerative disease, first described by Vossschulte and Börger in 1950. These cysts, often located near nerve roots, contribute to lower back pain, radiculopathy, and neurological deficits. Although the exact etiology of FJCs remains unclear, degenerative changes in the facet joints are implicated, with the L4-L5 level being most commonly affected. The association of these cysts with spondylosis and degenerative spondylolisthesis is well-documented, and advances in imaging have improved diagnostic accuracy. Surgical intervention is frequently necessary to prevent neurological complications and manage the high recurrence rate of FJCs. Common procedures include hemilaminectomy, laminotomy, partial facetectomy, and newer techniques such as laser-assisted endoscopic decompression and full-endoscopic interlaminar and transforaminal approaches. The Bumrungrad Spine Institute has been a leader in implementing the full-endoscopic interlaminar lumbar facet cyst resection technique since 2009, with 50 cases performed and long-term follow-up. However, the scarcity of documented outcomes highlights the rarity of these cases. This study aims to fill this gap by evaluating the outcomes of full-endoscopic interlaminar decompression for lumbar facet cyst removal, offering insights into its long-term effectiveness and safety. These findings could refine surgical approaches, enhance patient care, and advance understanding in managing lumbar facet cysts. Material and Methods: This retrospective, descriptive case series reviews medical records of patients who underwent full-endoscopic interlaminar lumbar facet cyst removal at Bumrungrad International Hospital between 2009 and 2023. After obtaining approval from the Hospital Administration, Bumrungrad International Institutional Review Board (BI/IRB), and patient consent per the Personal Data Protection Act (PDPA), relevant data were extracted from the Hospital Information System. Results: Fifty-three patients underwent lumbar facet cyst removal due to neurological complications. The mean age was 64.04 years (95% CI 63.17-64.91), with 71.15% being men. Most patients were overweight (mean BMI 23.53; 95% CI 22.66-24.40). Radiculopathy was most common at L4-5 (67.30%), followed by L5-S1 (17.30%). The average operation time was 123.67 minutes (95% CI 122.80-124.54). Among these, 48 patients had single-level decompression, while 4 required two-level decompression. Thirty-six were local patients, and 16 were international, returning home post-treatment. Eight patients had co-existing spondylolisthesis requiring fusion (15.38%). Postoperatively, 96.15% of patients reported significant pain relief, with 84.61% experiencing no pain. All patients were able to stand and walk immediately after anesthesia, with 97.67% discharged within 24 hours. Conclusion: Endoscopic interlaminar resection of lumbar facet cysts is an effective treatment for patients with neurological complications, demonstrating benefits over a 10-year follow-up period. To improve the follow-up rate, especially for international patients, a systematic and proactive follow-up strategy is recommended.

ID: 1966

RF342: BMI-related preoperative outcomes in lumbar fusion surgeries (OLLIF, MIS-TLIF, TLIF)

Amir Sharif ^1,2 , Hamid Reza Abbasi ¹

¹ Inspired Spine, Spine Surgery, Burnsville, MN, United States,

² Sana Regio Klinikum Pinneberg, Spine Surgery, Pinneberg, Germany

Introduction: Obesity is an increasing public health concern associated with increased perioperative complications and expense in lumbar spine fusions. While open and mini-open fusions such as transforaminal lumbar interbody fusion (TLIF) and minimally invasive TLIF (MIS-TLIF) are more challenging in obese patients, new MIS procedures like oblique lateral lumbar interbody fusion (OLLIF) may improve perioperative outcomes in obese patients relative to TLIF and MIS-TLIF. The purpose of this study is to determine the effects of obesity on perioperative outcomes in OLLIF, MIS-TLIF, and TLIF. Material and Methods: This is a retrospective cohort study. We included patients who underwent OLLIF, MIS-TLIF, or TLIF on three or fewer spinal levels at a single Minnesota hospital after conservative therapy had failed. Indications included in this study were degenerative disc disease, spondylolisthesis, spondylosis, herniation, stenosis, and scoliosis. We measured demographic information, body mass index (BMI), surgery time, blood loss, and hospital stay. We performed summary statistics to compare perioperative outcomes in MIS-TLIF, OLLIF, and TLIF. We performed multivariate regression to determine the effects of BMI on perioperative outcomes controlling for demographics and number of levels on which surgeries were operated. Results: OLLIF significantly reduces surgery time, blood loss, and hospital stay compared to MIS-TLIF, and TLIF for all levels. MIS-TLIF and TLIF do not differ significantly except for a slight reduction in hospital stay for two-level procedures. On multivariate analysis, a one-point increase in BMI increased surgery time by 0.56 ± 0.47 minutes (p = 0.24) in the OLLIF group, by 2.8 ± 1.43 minutes (p = 0.06) in the MIS-TLIF group, and by 1.7 ± 0.43 minutes (p < 0.001) in the TLIF group. BMI has positive effects on blood loss for TLIF (p < 0.001) but not for OLLIF (p = 0.68) or MIS-TLIF (p = 0.67). BMI does not have significant effects on length of hospital stay for any procedure. Conclusion: Obesity is associated with increased surgery time and blood loss in TLIF and with increased surgery time in MIS-TLIF. Increased surgery time may be associated with increased perioperative complications and cost. In OLLIF, BMI does not affect perioperative outcomes. Therefore, OLLIF may reduce the disparity in outcomes and cost between obese and non-obese patients.

ID: 2021

RF343: Efficacy and clinical outcomes of minimally invasive direct thoracic interbody fusion: a retrospective analysis

Amir Sharif ^1,2 , Hamid Reza Abbasi ²

¹ Sana Regio Klinikum Pinneberg, Spine Surgery, Pinneberg, Germany,

² Inspired Spine, Spine Surgery, Burnsville, MN, Germany

Introduction: A unique surgical approach - the minimally invasive direct interbody fusion (MIS-DTIF) - was previously introduced in our proof-of-concept study, which included four patients who underwent thoracic interbody fusion below the scapula at the T6/7 vertebral level. However, due to the novelty of this method, a report of associated operative parameters such as pain, function, and clinical outcomes from an expanded patient cohort was needed to assess the validity of our results. Material and Methods: Following IRB approval, data were analyzed retrospectively from electronic health records between 2014 and 2021. Inclusion criteria were patients ≥18 years old who underwent minimally invasive thoracic interbody fusion using the MIS-DTIF technique for at least one vertebral level. The primary outcomes included demographic/radiographic features (e.g., age). Secondary outcomes included perioperative clinical features (e.g., preoperative and ≥ 1-year final follow-up (FFU)). Tertiary outcomes included perioperative complications. Both preoperative and FFU patient-reported pain and functional outcomes (ODI scores) were analyzed using t-tests to establish significance. Results: A total of 13 patients who underwent MIS-DTIF surgery were observed, with eight male patients and five female patients. The average age was 49.2 years, with an average BMI of 30.5 kg/m². Of the surgeries included, the majority (69.23%) were 1-level thoracic vertebrae fusions - with 2-level fusions and ≥ 3-level fusions accounting for 15.38% and 15.38% of cases, respectively. The mean operative time was 58.9 ± 19.9 minutes, with an average fluoroscopy time of 285.7 ± 126.8 seconds and an average actual blood loss volume of 109.0 ± 79.0 mL. The average hospital length of stay was 1.1 (±1.7) days, and no clinically significant perioperative complications were observed in this patient cohort. The average follow-up period was 12.1 ± 9.6 months, with preoperative and FFU back pain visual analog scale (VAS) scores showing highly significant improvement (p < 0.001). In addition to pain reduction, quality of life improvements was noted, with significant differences in some of the ODI domains between preoperative and FFU scores (p < 0.05), as well as the overall total score between preoperative and FFU ODI assessment (p < 0.001) - both of which reflect increased patient function and decreased disability. Conclusion: This study provides further evidence for the safety and efficacy of the MIS-DTIF approach for surgical management of symptomatically refractory patients with thoracic disc herniation or stenosis owing to degenerative disc disease or compression fractures. Additionally, the data gathered suggests that this minimally invasive procedure offers many clinical benefits, including less tissue damage, decreased intraoperative blood loss, shortened surgery time, and shortened hospital length of stay. Finally, in addition to significant pain intensity improvement, this study showed that treated patients highly benefited from 'sleeping' and 'return-to-work' domains and other ODI functional domains in activities of daily living (ADLs). More clinical studies are recommended in larger patient cohorts to ascertain the findings reported in this study.

ID: 164

RF344: Analysis of related risk factors for vertebral refracture after percutaneous kyphoplasty in patients with osteoporotic vertebral compression fractures: a retrospective study of 182 patients

Yonghao Wu ¹ , Shuaiqi Zhu ¹ , Yuqiao Li ¹ , Chenfei Zhang ¹ , Weiwei Xia ¹ , Zhenqi Zhu ¹ , Kaifeng Wang ¹

¹ Peking University People's Hospital, Department of Spinal Surgery, Beijing, China

Introduction: The aim of this systematic retrospective study of 182 patients was to explore the risk factors for vertebral refracture after percutaneous kyphoplasty (PKP) in patients with osteoporotic vertebral compression fractures (OVCFs). Material and Methods: The records during hospitalization and outpatient follow-up of 495 patients with single-segment OVCFs who underwent single-entry PKP at our department, between March 2016 and August 2022, were extracted. Vertebral refracture was diagnosed based on a 4 or millimeter reduction in the height of the vertebral body, whether cemented, adjacent or distant compared with the height measured within the first 3 days of surgery. The evaluation indices used were as follows: age, gender, BMI, underlying disease, history of fracture at other sites, Hounsfield Units (Hu) on computed tomography (CT) at upper lumbar levels, volume of cement, postoperative anti-osteoporosis treatment, primary fractured vertebral segment, intravertebral vacuum cleft (IVC), preoperative and postoperative distance between the bone cement and anterior edge of the vertebral body, sagittal position of cement filling, contact between the bone cement and endplate, distance between the bone cement and vertebral endplates, collapse of the vertebral body(%), recovery rate of the vertebral anterior margin height(%), restoration of the Cobb angle(%), bone-cement distribution score, and bone cement leakage. Univariate analysis was performed to ascertain the possible risk factors associated with vertebral refracture following PKP, whereas binary logistic regression analysis was performed to identify the independent risk factors. The discrimination ability of the predictive indicators was assessed using the AUC of ROC curve. Results: After 6-42 months of follow-up, 182 patients were included, with a median 7.00-months follow-up, a mean age of 73.71 ± 8.420 years, 76.92% females and 187 re-fracture vertebrae. Patients were divided into nonvertebral refracture group(n=143) and vertebral refracture group (n = 39). The incidence of vertebral refracture after PKP ranged from 0.5 to 38 months, with 6.73 months on average. In univariate analysis, possible risk factors for vertebral refracture after PKP included low Hu at upper lumbar levels (p = 0.049), thoracolumbar junction fracture (p = 0.004), preoperative IVC (p = 0.001), high recovery rate of the vertebral anterior margin height (p = 0.023), low postoperative Cobb angle (p = 0.005), high restoration of Cobb angle (p<0.001), sagittal position of nonwhole vertebral body filling (p = 0.003), non-cement‒endplate contact (p = 0.003), high distance between bone cement and vertebral endplates (p = 0.006), low bone-cement distribution score (p<0.001), bone cement leakage (p = 0.007), and absence of postoperative anti-osteoporosis treatment (p<0.001). Binary logistic regression revealed that low Hu at upper lumbar levels (OR = 0.928, 95%CI0.897∼0.960, p < 0.001), preoperative IVC (OR = 18.328, 95%CI3.146∼106.759, p = 0.001), high restoration of the Cobb angle (OR = 1.037, 95%CI1.013∼1.061, p = 0.003) and postoperative anti-osteoporosis treatment (OR = 0.084, 95%CI0.017∼0.413, p = 0.002) were independently associated with vertebral refracture. Hu on CT, preoperative IVC, restoration of Cobb angle and absence of postoperative anti-osteoporosis treatment were of satisfactory predictive value for vertebral refracture, with the AUC of 0.838 (95%CI 0.762∼0.914), 0.643 (95%CI 0.555∼0.731), 0.746 (95%CI 0.640∼0.852) and 0.683 (95%CI 0.577∼0.789), respectively. Conclusion: Low Hu at upper lumbar levels, preoperative IVC and high restoration of Cobb angle were factors contributing to vertebral refracture after PKP. Conversely, postoperative anti-osteoporosis treatment was observed to be a protective factor against subsequent vertebral refracture.

ID: 2756

RF345: High-grade lumbar spondylolisthesis treated with minimally invasive surgery - Transforaminal lumbar interbody fusion, a prospective analysis of the functional outcome with more than 2 years of follow-up

Shrey Binyala ¹ , Vishal Peshattiwar ¹

¹ Kokilaben Dhirubhai Ambani Hospital, Mumbai, Maharashtra, Mumbai, India

Introduction: Over decades lumbar inter-body fusion has been used to treat various lumbar spine diseases. Among various fusion methods, posterior approaches are most commonly used including PLIF and TLIF. TLIF achieves decompression and inter-body arthrodesis with lesser tissue injury and a significantly decreased thecal sac retraction. However, there are concerns about muscle atrophy due to the extensive skin incisions and peri-vertebral muscle detachment in conventional open surgeries. With the advent of minimally invasive techniques, there is preservation of much of the lumbar musculature due to splitting the muscle and reduced intraoperative bleeding. High-grade spondylolisthesis poses unique questions like achieving adequate reduction to restore spino-pelvic alignment or nerve root injury during the process of reduction. We aim to evaluate, the clinical outcomes and the complications of patients who underwent MIS TLIF for high-grade lumbar spondylolisthesis. Material and Methods: This retrospective analysis was conducted in between 2017 to 2022 and a total of 103 patients undergoing MIS-TLIF between February 2017 to February 2022 for grade 3 or above spondylolisthesis, according to Myerding classification, were included in our study. Parameters like cage size, disc height ratio, post-op VAS and ODI score, reduction of the grade of anterolisthesis, and associated complications were used to evaluate our procedure in the study. Results: Mean age 47.3 ± 8.5 years. Our study consisted of patients of both genders with females being 59.2% of the sample. All the patients were operated on at a single institute, by a single surgeon. Out of the bed mobilization was done on the same day of surgery. Bridwell Grade 1 fusion was seen in 101 patients by the end of two years. We observed one case with breakage of S1 screw at 6 months follow-up, however, CT scan showed a complete fusion of the L5 and S1 vertebral bodies. Conclusion: MIS-TLIF is a safe and effective method for treating high-grade lumbar spondylolisthesis showing recurrent, replicable satisfactory clinical outcomes and minimal complications with an excellent union rate. However, being a single-center-based study is our limitation.

ID: 1959

RF346: Risk factors for poor outcome following minimally invasive discectomy

Atif Ali ¹

¹ Ghurki Trust Teaching Hospital Lahore, Orthopaedics and Spine, Lahore, Pakistan

Objective: An analysis of prospectively collected data from a randomized controlled trial was conducted to identify risk factors related to poor outcomes in patients who underwent minimally invasive discectomy. Methods: Patients were divided into satisfied and dissatisfied subgroups based on Oswestry Disability Index (ODI), visual analog scale (VAS) back pain score (VAS-back), and leg pain score (VAS-leg) at short-term and midterm follow-up according to the patient acceptable symptom state threshold. Demographic characteristics, radiographic parameters, and clinical outcomes between the satisfied and dissatisfied subgroups were compared using univariate and multivariate analysis. Results: A total of 222 patients (92.1%) completed a 2-year follow-up, and the postoperative ODI, VAS-back, and VAS-leg were significantly improved after surgery compared to preoperatively. Multivariate analysis indicated that older age (2.6%), lateral recess stenosis (4.6%), and lower baseline ODI (2.7%) were related to poor short-term functional improvement. Higher baseline VAS-back (4.8%) was associated with poor short-term relief of back pain. In comparison, the absence of decreased sensation (1.9%) and far-lateral disc herniation (0.4%) were associated with poorer short-term relief of leg pain. Lumbar facet joint osteoarthritis was identified as a risk factor for poor functional improvement (3%) and relief of back pain (3.1%). Disc protrusion (3.6%) predicted poorer relief of back pain at midterm follow-up. Conclusion: Specific patient characteristics and clinical factors can influence surgical outcomes and should be considered when determining the suitability of patients for minimally invasive discectomy.

Keywords: Minimally invasive discectomy, Risk factors, Disability, Back pain, Leg pain

ID: 396

RF347: Cement augmented pedicle screw fixation and vertebroplasty under local anaesthesia

Varun Agarwal ¹

¹ Rohilkhand Medical College and Hospital, Orthopedics, Bareilly, India

Introduction: A high rate of implant failure has been frequently seen in osteoporotic spines. Since the most of the patients with osteopororsis are in elderly age group and are not fit for General anesthesia due to various systemic reasons. Cement augmented cannulated pedicle screw fixation aims to enhance the stability and fixation strength in patients with compromised bone quality. Material and Method: Forty-five patients (23 women, 22 men), mean age of 71.37 years (range, 53-94 y), with osteoporosis (T score > 2.5) and who were not fit for General anesthesia with various spinal diseases underwent spinal decompression and instrumentation with PMMA augmentation of cannulated pedicle screws. Total of 214 pedicle screw were inserted 28 individuals had 4 and 17 had 6 pedicle screw insertion with augmentation. Preoperative and postoperative visual analog scale scores for pain and the Oswestry disability index questionnaire data were analyzed. Screw migration, which is the distance from the screw tip to the anterior cortex and the upper endplate of the vertebra, was also evaluated immediately after surgery. Mean follow-up was up to 15.3 months. Result: The mean preoperative VAS was 8.76 (range 7-10). Being the most common complaint, pain showed significant improvement, and the mean postoperative VAS became 2.24 (range 0-5) recorded during the last clinical control (p < 0.001). Stretch signs and claudications were the main indications for surgery in nine patients. Oswestry disability index Patients showed significant improvement in the quality of life as measured using the ODI (p < 0.001). There was no significant vertical screw migration when the screws’ distances were compared just after the operation and at the final follow-up (p > 0.01). However, significant horizontal screw migration was found in lesions below the L2 level (p < 0.01). There was no major neurovascular injury, except in 1 patient, who had persistent left thigh pain due to cement leakage at the L1 level, and the symptom was controlled with analgesics. All the patients tolerated the surgery well under Local Anesthesia with MAC. Conclusion: The use of this technique in patients with bone softening caused by osteoporosis, infection or malignancy is recommended for being helpful for increasing the stabilisation of fixation and preventing screw loosening in medically unfit patients. It is safe and has very less complications.

ID: 1445

RF348: Single surgeon learning curve and outcomes of o-arm minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF)

Kia Teng Lim ¹ , Youheng Ou Yang ² , Cassie Yang ¹ , Alagan Gnanam ¹ , Gek Hsiang Lim ³ , Rui Xiang Toh ² , Reuben Soh ²

¹ Ministry of Health Holdings Pte Ltd (MOHH), Singapore, Singapore,

² Singapore General Hospital, Dept of Orthopaedic Surgery, Singapore, Singapore,

³ Singapore General Hospital, Health Services Research Unit, Singapore, Singapore

Introduction: O-arm navigated minimally invasive transforaminal lumbar interbody fusion (O-MIS-TLIF) has been shown to increase the accuracy of interbody cage and pedicle screw placement compared to C-arm guided placement and conventional open techniques. However, there is a known steep learning curve associated with MIS spine surgeries. The aim of this study was to assess the learning curve in O-MIS-TLIF. Materials and Methods: Retrospective analysis was conducted on 82 patients who underwent O-MIS-TLIF under a single surgeon, with follow-up of 2 years. The learning curve was assessed using logarithmic curve-fit regression analysis. The 80% learning milestone based on corrected operative time per level was identified to be case 47. Patients were divided into the “early” group (n = 47), defined as patients who were operated on from the first case up to when 80% learning milestone was reached, and “late” group (n = 35) comprising patients after the 80% learning milestone. Radiological, surgical outcomes and patient reported outcome measures (PROMs) at 1 month, 3 months, 6 months, and 2 years were compared between both groups. Results: Corrected operative time per level gradually decreased as cases progressed. 55 patients underwent single-level O-MIS-TLIF, whilst 27 patients underwent double-level O-MIS-TLIF. In the single-level O-MIS-TLIF group, 80% learning milestone was achieved at case 38. There was a significant difference in operative times before and after the milestone achievement (median 205 minutes (IQR: 165, 235) versus median 178 minutes (IQR: 155,190, p = 0.01). In the double-level O-MIS-TLIF group, 80% learning milestone was achieved at case 5, however the corrected operative times before and after remained equivalent (median 190 minutes (IQR: 181, 209) versus median 197 minutes (IQR 154, 216), p = 0.87). Across all O-MIS-TLIF patients, patients who are at ≤ 80% learning milestone (n = 47) and patients at > 80% learning milestone (n = 35) did not have significant differences in radiological outcomes such as cage migration, cage subsidence, end plate perforation, fusion at 2 years. Post-operative complications such as intra-operative blood loss, decrease in post-op hemoglobin levels, time to ambulation, time to stairs, length of hospitalization, superficial infection rates, revision surgery rates remained insignificant between both groups. In terms of PROMs, at 6 months, the patients in the “early” group experienced greater satisfaction with surgery (median 84.6 out of 100, IQR: 72.1, 87.5) compared to those later (median 73.3 out of 100, IQR 61.1, 80.0) (p = 0.04), but remained insignificant at 2 years. Patients in the “early” group had higher RAND-36 physical function scores (median 75, IQR: 25, 100) compared to those later (median 0, IQR: 0, 75) at 6 months (p = 0.047) but remained insignificant at 2 years. All other outcomes such as numeric rating scale lower limb pain, leg numbness, RAND-36 social function, bodily pain, general health, vitality, mental health, Oswestry Disability Index for back pain and neurogenic symptoms remained insignificant across all time points. Conclusion: Long-term outcomes remained equivalent between the early and late group of patients. In considering navigated MIS-TLIF, an approximation of 47 cases is required to reach 80% of the learning milestone in the learning curve expected for O-MIS-TLIF.

ID: 944

RF349: Anatomical correlation of the lumbar region applied to the anterior retroperitoneal lumbar intervertebral approach: a new classification

Diana Chávez ¹ , Ricardo Gomez Lopez ¹ , Alberto Perez ¹

¹ Hospitales Angeles, Neurosurgery, Mexico, Mexico

Introduction: The anterior lumbar retroperitoneal approach has evolved into one of the predominant surgical techniques for treating discogenic back pain at the L5-S1 level. While various surgical methods have been developed to access the anterior lumbar spine, the mini-open retroperitoneal approach has become the most widely accepted. This technique allows exposure of up to three disc spaces from L3-L4 to L5-S1, enabling direct manipulation of vascular structures. The overall complication rate for anterior lumbar approaches is 6.4%, with incidental peritoneal opening and injuries to the left iliac vein being among the most common complications. Risk factor classification during preoperative planning can help predict complication rates in anterior lumbar approaches. The objective of this study is to analyze the correlations between the surgical difficulty of the anterior lumbar approach and anatomical characteristics in MRI images. The aim is to develop a simple classification system that provides guidelines for appropriate case selection and evaluates the potential risks associated with the technique. Material and Methods: A prospective analysis was conducted using imaging and records from Hospital Angeles México and Hospital Ángeles Pedregal to evaluate the vascular anatomical correlation in the L3L4, L4L5, and L5S1 segments through MRI in patients over 18 years old who underwent ALIF and TDR between 2020-2024. Five spine surgeons (APC, EC, AG, SDB, PC) will assess the imaging studies. Descriptive statistics will be performed; for qualitative variables, Fisher's exact test and Chi-square (X2) tests will be used; for quantitative variables, Student's t-test or Mann-Whitney U test will be applied. A p-value of ≤ 0.05 will be considered significant. The statistical software GraphPad Prism V.10.1.0 will be utilized for analysis. Results: Based on the obtained scores, they were classified into difficulty grades I (0-4), II (4-8), and III (9-12). This classification took into account the vascular anatomy layout, bifurcation height, calcification of the iliac artery at levels L3, L4, L5, S1, presence of osteophytes, as well as the measurement of the perivascular fat pad. The latter allows for greater mobilization of vascular structures to access the intervertebral disc during anterior lumbar approach. This resulted in a proposed tool that is applicable and reproducible with high predictive value for complications. Conclusion: This new classification is a reliable and reproducible tool for studying the regional lumbar retroperitoneal anatomy using MRI before anterior lumbar approach interventions from L3 to S1. We propose that patients who present a higher degree of difficulty in this classification should be evaluated for an alternative approach.

ID: 2596

RF350: Comparison of biportal endoscopic and microscopic tubular paraspinal approach for foraminal and extraforaminal lumbar disc herniation

Hyun-Jin Park ¹

¹ Hallym University Kangnam Sacred Heart Hospital, Seoul, South Korea

Introduction: Foraminal and extraforaminal lumbar disc herniation (FELDH) is an important pathological condition that can lead to lumbar radiculopathy. The paraspinal muscle-splitting approach introduced by Reulen and Wiltse is a reasonable surgical technique. Minimally invasive procedures using a tubular retractor system have also been introduced. However, surgical treatment is considered more challenging for FELDH than for central or subarticular lumbar disc herniations (LDHs). Some researchers have proposed uniportal extraforaminal endoscopic lumbar discectomy through a posterolateral approach as an alternative for FELDH, but heterogeneous clinical results have been reported. Recently, the biportal endoscopic paraspinal approach has been suggested as an alternative. To compare the clinical outcomes of biportal endoscopic (BE) and microscopic tubular (MT) paraspinal approach for decompressive foraminotomy and lumbar discectomy (ParaLD) in patients with FELDH. Material and Methods: Ninety-one consecutive patients with unilateral lumbar radiculopathy and FELDH underwent paraLD. Among them, 43 underwent BE-ParaLD (group A), and the remaining 33 underwent MT-ParaLD (group B). Demographic and perioperative data were collected. Clinical outcomes were evaluated using the visual analog scale (VAS) for back and leg pain, the Oswestry Disability Index (ODI) for spinal disability, and the modified MacNab criteria for patient satisfaction. Postoperative complications and reoperation rates were also evaluated. Results: Totally, 76 patients were included in the final analysis. The demographic and preoperative data were not statistically different. All patients showed significant improvements in VAS-Back, VAS-Leg, and ODI scores compared to baseline values (p < 0.05). The improvement in VAS-Back was significantly better than that in group A on postoperative day 2 (p < 0.001). However, all clinical parameters were comparable between the two groups after postoperative year 1 (p > 0.05). According to the modified MacNab criteria, 86.1% and 72.7% of the patients were excellent or good in groups A and B, respectively. No intergroup differences were observed (p = 0.367). In addition, there were no differences in the total operation time or amount of surgical drainage. Postoperative complications were not significantly different between the two groups (p = 0.301); however, reoperation was significantly higher in MT-ParaLD (p = 0.035). Conclusion: BE-ParaLD is an effective treatment for FELDH and is an alternative to MT-ParaLD. In particular, BE-ParaLD has the advantages of early improvement in postoperative back pain and low reoperation rates.

ID: 1415

RF351: The perioperative efficacy and complication of biportal endoscopic, microtubular, and open lumbar laminectomy for lumbar stenosis: a comparative cohort analysis

Don Park ¹ , Thomas Olson ² , William Sheppard ²

¹ UC Irvine, Orthopaedic Surgery, Orange, United States,

² UCLA, Or, Santa Monica, United States

Objective: This study compares the efficacy and complications biportal endoscopic unilateral laminectomy for bilateral decompression (ULBD), microtubular laminectomy, and open laminectomy for one- and two-level lumbar laminectomy using an early recovery after surgery (ERAS) protocol. Methods: A retrospective analysis was conducted on 125 patients who underwent one- or two-level lumbar laminectomies with a preoperative indication of primary central canal stenosis. Trauma, tumor, infection, and revision cases were excluded. The cohort included 44 endoscopic, 31 microtubular, and 50 open cases with minimum 90-day follow up. These were performed at a single academic institution by fellowship-trained spine surgeons. ERAS protocol emphasized multimodal analgesic control in the perioperative period before and after surgery, along with early mobilization. Patient demographics, surgical outcomes, and postoperative complications were compared. Results: The demographic characteristics, including age, sex, BMI, ASA score, and Charlson Comorbidity Index, were statistically similar across the groups. The distribution of single versus two-level surgeries and the specific levels addressed were comparable. Open procedures had a significantly longer length of stay (mean 2.0 days) compared to endoscopic (1.1 days) and microtubular (0.9 days) procedures (p = 0.0198). Microtubular surgeries had the shortest surgical duration (107 minutes) compared to endoscopic (144 minutes) and open (145 minutes) procedures (p = 0.0028). There was no significant difference in intraoperative or postoperative narcotic use among the groups. Estimated blood loss (EBL) was significantly higher in open procedures (mean 97 mL) compared to microtubular (45 mL) and endoscopic (7 mL) procedures (p < 0.0001). Despite the differences in EBL, there was no difference in transfusion rate, which was zero across all groups. Drain utilization was highest in endoscopic procedures (100%) but with shorter duration and lower total output compared to open (p < 0.0001). Microtubular procedures had minimal drain usage. Endoscopic and microtubular procedures had a higher incidence of transient postoperative radiculitis (20% and 32%, respectively) compared to open (6%) (p = 0.0087). Open laminectomies had a significantly higher rate of dural tears (20%) compared to endoscopic (2%) and microtubular (6%) procedures (p = 0.0178). Revision surgery was more common in the microtubular group (16%) due to persistent symptoms and incomplete decompression, compared to 0% in the endoscopic group and 4% in the open group (p = 0.0093). Conclusion: When comparing similar patients undergoing one- and two-level laminectomies under the ERAS protocol, minimally invasive spine surgery (MIS) techniques are associated with shorter hospital stays, lower EBL, and fewer severe complications such as dural tears compared to open laminectomy. Endoscopic decompression also demonstrates a lower revision surgery rate compared to microtubular laminectomy, suggesting superior efficacy in achieving adequate decompression. These findings support the effectiveness, safety, and accelerated recovery of minimally invasive and endoscopic techniques for the treatment of lumbar stenosis.

ID: 1748

RF352: Early clinical outcomes of ULBD+Endolif for lumbar spinal stenosis with spondylolisthesis under full-view spine endoscopy

Kunfeng Song ¹ , Haijun Ma ¹

¹ Third People's Hospital of Henan Province, Minimally Invasive Spine Surgery Center, ZhengZhou, China

Introduction: This study aims to evaluate the early clinical outcomes of unilateral laminotomy for bilateral decompression (ULBD) combined with percutaneous interbody fusion (Endolif) under full-view spine endoscopy for the treatment of lumbar spinal stenosis with spondylolisthesis. Material and Methods: A retrospective analysis was conducted on 86 patients treated with this technique from January 2020 to December 2022. The average age of the patients was 59.6 years, and all cases involved L4/5 segment Grade I or II spondylolisthesis. All patients were followed up for at least 12 months. Results: The average operation time was 195.3 minutes, the average blood loss was 75.6 ml, and the average hospital stay was 8.5 days, with patients mobilizing on the 2.5th postoperative day. At the final follow-up, the Visual Analog Scale (VAS) scores for back pain and leg pain decreased from 7.8 and 6.9 to 2.1 and 1.8, respectively, and the Oswestry Disability Index (ODI) score decreased from 57.3% to 24.7%. These differences were statistically significant (p < 0.001). At the 12-month follow-up, the Bridwell Grade I and II fusion rates were 85.6% and 14.4%, respectively. Complications included transient nerve root irritation symptoms in 2 cases (2.3%) and superficial wound infection in 1 case (1.2%). Conclusion: The ULBD+Endolif technique under full-view spine endoscopy is a safe and effective method for treating lumbar spinal stenosis with spondylolisthesis, offering advantages such as minimal invasiveness, reduced blood loss, and rapid recovery. This technique achieves adequate neural decompression and interbody fusion, significantly improving patients' pain symptoms and functional status. It represents a promising minimally invasive surgical approach. However, further studies are needed to evaluate its long-term efficacy and suitability for specific patient populations.

ID: 2330

RF353: Comparison of safety and efficacy of different anesthesia methods for percutaneous endoscopic lumbar discectomy: a network meta analysis

Bin Zheng ¹

¹ Peking University People's Hospital, Spine Surgery, Beijing, China

Introduction: The objective of this study was to systematically evaluate the safety and efficacy of local anesthesia, general anesthesia and epidural anesthesia in percutaneous endoscopic lumbar discectomy (PELD). Material and Methods: We searched Pubmed, EMBASE and OVID databases for all relevant studies. All statistical analysis was performed using STATA 17.0. Results: 14 studies were finally included, comprising 7 randomized controlled trials and 7 retrospective studies. The total number of subjects across these studies was 1655, with 316 undergoing general anesthesia, 789 undergoing local anesthesia, and 550 undergoing epidural anesthesia. The meta-analysis of pairwise comparisons suggests that there are no differences among epidural, general anesthesia, and local anesthesia in terms of postoperative VAS, ODI, and surgery time. Regarding complications, general anesthesia has a higher complication rate compared to local anesthesia, but there are no differences between epidural and general anesthesia or between epidural and local anesthesia. In terms of anesthesia satisfaction, both general and epidural anesthesia have higher satisfaction rates compared to local anesthesia, with no significant difference between general and epidural anesthesia. The ranking of the best probabilities shows that epidural anesthesia has the lowest postoperative VAS scores, general anesthesia has the lowest ODI scores, local anesthesia has the fewest complications, and epidural anesthesia has the highest anesthesia satisfaction. Conclusion: Local anesthesia, general anesthesia, and epidural anesthesia are all safe and effective methods for PELD. Local anesthesia has advantages in complications and operation time. Epidural anesthesia is most advantageous in postoperative VAS scores, and general anesthesia is most advantageous in anesthesia satisfaction and postoperative ODI.

ID: 820

RF354: Dimensional study of lumbar interlaminar window for endoscopic spine surgery

Marcos Vaz de Lima ^1,2 , João Paulo Trecco ¹ , Eduardo Achar Filho ¹ , Marco Moscatelli ³

¹ Santa Casa de São Paulo, São Paulo, Brazil,

² Instituto Tecnológico de Aeronáutica - ITA, São José dos Campos, Brazil,

³ NEUROLIFE, Natal, Brazil

Introduction: Lumbar spine endoscopic surgery has gained popularity due to its numerous advantages over conventional open techniques, such as reduced tissue trauma, postoperative pain, and infection risk, as well as faster recovery times and early patient mobility. However, despite advancements in endoscopic techniques, challenges remain with L5-S1 hernias, migrated hernias, and other conditions due to spinal anatomy. The interlaminar approach, described by Ruetten et al., addresses these issues, but the success of this technique depends on the size of the interlaminar window. This study aims to measure the dimensions of the lumbar interlaminar windows at levels L3-L4, L4-L5, and L5-S1 in patients with various lumbar pathologies. Methods: We conducted a retrospective study analyzing 469 anteroposterior lumbar spine radiographs from patients who visited an orthopedic emergency department between 2018 and 2020. Radiographs with spinal deformities, fractures, or poor imaging quality were excluded. Measurements of the vertical and horizontal dimensions of the interlaminar windows were taken using the Radiant software. The sample was stratified by age and sex. Results: Significant correlations were found between the size of the interlaminar windows and patient demographics. The horizontal dimension of the L4 and L5 interlaminar windows showed the strongest positive correlation (r = 0.507, p < 0.001). Differences between sexes were also observed, with men having larger interlaminar windows on average compared to women. Patients younger than 49 years had wider horizontal windows, particularly at L5, where the mean dimension was 3.075 compared to 2.905 in patients aged 50 and older. Discussion: The findings indicate that larger interlaminar windows at L4-L5 and L5-S1 facilitate endoscopic access without the need for bone drilling, while narrower windows at higher levels may require lateral drilling. The results also highlight the influence of age and sex on the size of the interlaminar window, which should be considered in preoperative planning to optimize surgical outcomes and reduce complications. Conclusion: Preoperative assessment of interlaminar window dimensions is essential for successful lumbar endoscopic surgery, particularly in complex cases. Surgeons should account for anatomical variations based on patient age and sex to ensure safe and effective surgical approaches.

ID: 1586

RF355: Comparative outcomes of robotic-assisted versus free-hand techniques in adult spinal deformity surgery: a retrospective analysis of postoperative complications and recovery

Ved Vengsarkar ^1,2 , Jialun Chi ² , Arsany Yassa ¹ , Xudong Li ²

¹ Rutgers New Jersey Medical School, Department of Orthopaedic Surgery, Newark, United States,

² University of Virginia School of Medicine, Department of Orthopaedic Surgery, Charlottesville, United States

Introduction: Adult spinal deformity (ASD) represents a challenging area in spinal surgery due to its complexity and the high potential for postoperative complications, especially as it relates to prior malpositioned hardware. Conventional free-hand surgical techniques have been the mainstay for correcting these deformities, but advancements in technology have introduced robotic-assisted surgery as an alternative. While robotic systems have promised enhanced precision for pedicle screw placement, improved alignment, and potentially fewer complications, the comparative efficacy and morbidity of robotic-assisted versus free-hand techniques remains underexplored in the context of ASD. This study aims to retrospectively analyze immediate postoperative outcomes between patients undergoing ASD correction via robotic-assisted techniques and those receiving traditional free-hand surgery to guide future surgical decision-making and potentially influence standards in spinal deformity correction. Material and Methods: A retrospective review was performed using the PearlDiver national database. The study included all patients over 18 who underwent a posterior fusion of at least 7 segments from 2015 to 2022Q2. Two separate cohorts were created based on the use of robotic assistance (RA) or free-hand (FH). Utilization of three-column osteotomy, posterior column osteotomy, and pelvic fixation in both groups was also determined. Propensity score matching for 2 groups was performed based on age, sex, and relevant comorbidities. Multivariate logistic regression was used to compare 90-day medical and surgical complications. 90-day emergency department (ED) visits and readmission were also documented. Results: The RA group demonstrated a significantly lower incidence of atelectasis (3.0% vs. 6.8%; p = 0.018), respiratory failure (2.7% vs. 6.7%; p = 0.010), pleural effusion (3.3% vs. 7.0%; p = 0.021), and pneumonia (2.1% vs. 6.0%; p = 0.004) compared to the free-hand group. Additionally, the RA group also demonstrated a reduced incidence of spinal cord deficits (1.2% vs. 3.4%; p = 0.048) and a shorter average length of stay (LOS), in days (8.1 ± 8.3 vs. 10.2 ± 12.8; p = 0.009). Conclusion: Robotic-assisted surgery has demonstrated superior pedicle screw placement accuracy previously but the degree to which these outcomes are clinically meaningful have been unclear. In the present study, we discover that robotic assistance leads to improved short-term medical and surgical outcomes. Future research should focus on prospective, multicenter trials to validate these results and evaluate long-term outcomes.

ID: 2930

RF356: The effect of BMI on outcomes measured in spinal endoscopic surgery

Froukje Koremans ^1,2 , Ashish Diwan ³ , Gayani Petersingham ³ , Prashanth Rao ^1,2,4,5

¹ Brain and Spine Surgery, Bella Vista, Australia,

² University of New South Wales, Sydney, Australia,

³ Spine Service, University of New South Wales, Department of Orthopaedic Surgery, Sydney, Australia,

⁴ Norwest Private Hospital, Department of Neurosurgery, Bella Vista, Australia,

⁵ Macquarie University Hospital, Department of Neurosurgery, Macquarie Park, Australia

Introduction: Obesity affects 67% of Australian adults and is a significant public health issue. The influence obesity has on spinal surgery outcomes is an essential area of research. The purpose of this retrospective study was to demonstrate the impact of BMI on the outcomes of endoscopic spinal surgery in Australia across five Neurosurgical practice centres. Material and Methods: A total of 227 patients who underwent endoscopic surgical intervention for a spinal condition between August 2021 to March 2024 are included. An evaluation of patient data include demographics, preoperative clinical status, intraoperative details, complications and postoperative outcomes, was conducted. The surgical outcomes measured include Visual Analogue Scale (VAS) leg and back pain score, Oswestry Disability Index (ODI), Roland-Morris Disability Questionnaire (RMDQ) score and the Quality-of-life EuroQol-5 Dimensions Questionnaire (EQ5D) health level. A statistical analysis to determine the connection between BMI values and surgical outcomes, was conducted using descriptive statistics and Spearman’s Rho rank correlations. A p-value < 0.05 was considered as a statistical significance. Results: the mean BMI of the cohort study was 29.90 ± 5.99, with 82.61% of patients in the BMI category of overweight, obese and morbidly. The analysis revealed a significant negative correlation between BMI categories and 12-week postoperative improvements in ODI (r = -0.253, p = 0.005), RMDQ (r = -0.256, p = 0.007), and VAS Leg pain scores (r = -0.185, p = 0.044), indicating that higher BMI is associated with less immediate postoperative improvement. However, no significant correlation was found between BMI and Delta-VAS Back (r = -.145, p = 0.247), Delta-VAS Leg (r = -.096, p = .071), Delta-EQ5D (r = .166, p = .179) at 6-9 months. The mean difference in outcome scores showed that higher BMI categories were associated with less initial improvement in ODI scores compared to a shared control. However, after 6-9 months BMI categories did not influence the VAS or ED5D scores. Ultimately improvement in pain scores was observed for all BMI categories postoperatively. Conclusion: BMI has no significant relationship with long-term improvements in pain following endoscopic spinal surgery. However, in the short-term, BMI does inversely affect surgical recovery and disability. This demonstrates endoscopic surgical treatments is suitable for pain and disability management for patients in all BMI categories, after the initial recovery period. These findings allow Surgeons to set realistic expectations for functional improvement at postoperative time intervals when discussing endoscopic procedures with obese patients. This study highlights the efficiency of endoscopic procedures regardless of the weight of a patient while also emphasising the importance of addressing obesity as a modifiable risk factor to improve immediate patient outcomes following endoscopic spinal surgery.