Oral Presentations

OP01: Spine Trauma Surgical 1

ID: 523

A001: Survival and patient-reported outcomes following spinal fractures in patient with and without ankylosing spondylitis, a comparative nationwide propensity score-matched analysis

Victor Gabriel El-Hajj ¹ , Erik Edström ¹ , Adrian Elmi Terander ¹

¹ Karolinska Institutet, Stockholm, Sweden

Introduction: The evidence on ankylosing spinal disorders (ASDs), encompassing ankylosing spondylitis (AS) and diffuse idiopathic skeletal hyperostosis (DISH), in the context of spinal fractures stems from studies with relatively small sample sizes. There are no studies addressing patient reported (PROMs) and health-related quality of life outcomes associated with spinal fractures in this patient population. We hence aimed to investigate differences in treatment-related complications, mortality, and PROMs in patients with and without ASD. Material and Methods: All surgically and conservatively treated patients with spine fractures were identified through the nationwide Swedish Fracture Registry (SFR). Propensity score matching using KNN with a ratio of 1:1 was used to balance the groups. Primary outcomes included mortality and PROMs. For surgically treated patients, complications and reoperation rates were also retrieved. Results: A total of 14,604 patients without ASD and 1,368 patients with ASD were included. High-energy injuries were less frequent in patients with ASD (13% vs. 24%; p < 0.001). Patients with concomitant ASD were less likely to be neurologically intact on admission (90% vs 94%; p < 0.001). There were 1,707 surgically treated fracture patients without, and 559 with ASD. A higher overall risk of reoperation was found among patients with ASD after matching (9.1% vs. 3.4%; p = 0.007). Surgical site infections requiring reoperation (p = 0.012), unlike fixation failure or CSF leaks requiring reoperation (p ≥ 0.05) were found to be more common among patients with ASD. Post-matching, there were no differences in the overall survival between ASD and non-ASD patients (p > 0.05). Patients with spine fractures and concomitant ASD had significantly worse PROMs as indicated by the EQ5D index. However, this difference was only notable at 1-month following the injury (p = 0.002) and later resolved upon reassessment at 1-year (p = 0.31). Conclusion: Surgically treated patients with ASD experienced higher rates of postoperative complications as well as reoperations following surgery. Recovery after spinal fracture occurred at a slower pace in patients with concomitant ASD, although resulting in similar outcomes at 1-year postoperatively regardless of ASD. Finally, ASD alone did not exhibit a significant association with increased mortality risk over time.

ID: 2415

A002: Risk factors for 1-year mortality in patients over 65 years of age with a tramatic spine injury

Joost Rutges ¹ , Harmen Kuijten ² , Chiara Bruggink ¹ , Nathan Marhold ³ , Cumhur Oner ² , Harmke Polinder-Bos ⁴ , Jan van Ditshuizen ³ , Max Reijman ¹

¹ Erasmus MC, Orthopaedics and Sport Medicine, Rotterdam, Netherlands,

² UMC Utrecht, Orthopedics, Utrecht, Netherlands,

³ Erasmus MC, Trauma Research Unit Department of Surgery, Rotterdam, Netherlands,

⁴ Erasmus MC, Department of Internal Medicine, sector of Geriatric Medicine, Rotterdam, Netherlands

Background: The global population of individuals ≥ 65 years is increasing rapidly. Additionally, the incidence of traumatic spine injury in this patient group has increased the past decade, with 33%. Moreover, an unexpectedly high 1-year mortality rate up to 25% has been reported recently for this patient group. This study aims to identify risk factors for 1-year mortality in patients ≥ 65 years with traumatic spine injuries and compare them with risk factors of adult patients < 65 years. Methods: A retrospective analysis was conducted on 1,079 adult patients (> 18 years) with traumatic spine injuries treated at a level I trauma center between 2018 and 2022. Data were collected from the Dutch National Trauma Registry and electronic patient files, including patient demographics, injury characteristics, treatments, complications, and 1-year mortality rates. Univariate and multivariate logistic regression analyses were performed to identify factors related to 1-year mortality in age groups 18-65 and ≥ 65 years. Results: Of 1,079 patients, 360 (33.4%) were ≥ 65 years and 719 (66.6%) < 65 years. The 1-year mortality rate was significantly higher in patients ≥ 65 years compared to those < 65 years, 87 vs 72 (24.2% vs. 10.0%, p < 0.001). In the ≥ 65 group, the median age was 75.0 years (IQR 10.1), 222 (61.7%) were male, the median Injury Severity Score (ISS) was 17.0 (IQR 15.0), 54 (25.5%) frail patients according Modified Frailty Index-5 (MFI-5) and a spinal cord injury was present in 73 (20.3%) cases. In the < 65 years group the median age was 42.5 years (IQR 26.2), 588 (75.4%) were male, the median ISS was 21.0 (IQR 17.0), 23 (5.4%) frail patients according the MFI-5 and spinal cord injury was present in 127 (17.7%) cases. Univariate analysis identified age, sex, American Society of Anesthesiologists (ASA) score, AO type A fracture, AO type C fracture, presence of a spinal cord injury, thoracic fractures, lumbar fractures and ISS as factors with an association to 1-year mortality in patients > 65 years. In patients < 65 years, ASA score, AO type A fracture, modified frailty index, cervical fractures, surgical treatment and ISS were identified. Multivariate analysis in patients >65 years confirmed age (OR 1.14, p < 0.001), ASA score > 3 (OR 10.7, p = 0.032), and ISS (OR 1.08, < 0.001) as independent factors for mortality one year after a traumatic spinal cord injury. For patients < 65 years associated factors were age (OR 1.03, p = 0.011), ISS (OR 1.09, p < 0.001) and ASA score > 3 (OR 5.61 p = 0.001). Conclusion: This study confirms a significantly higher 1-year mortality rate in spine injury patients ≥ 65 years compared to patients < 65 years. The identification of similar risk factors across both age groups suggests that the underlying cause of the increased mortality remains unknown. These findings underscore need for further research to elucidate the specific mechanisms contributing to increased mortality in older patients. Concurrently, they emphasize the importance of patient-centered decision-making processes and the implementation of targeted interventions and specialized care protocols for spine injury patients over 65 years of age.

ID: 1230

A003: Validation of the AO Spine PROST (Patient Reported Outcome Spine Trauma) version 1.1 in patients with longstanding spinal cord injury

Marcel Post ¹ , Aline Hakbijl ¹ , Sylvia Egberts ¹ , Janneke Stolwijk ² , Rutger Osterthun ³ , Tijn van Diermen ⁴ , Cumhur Oner ⁵ , Olesja Hazenbiller ⁶ , Said Sadiqi ^5,7 , Charlotte Dandurand ⁷

¹ De Hoogstraat Rehabilitation, Utrecht, Netherlands,

² Centre of Excellence for Rehabilitation Medicine, UMC Utrecht Brain Centre, University Medical Centre Utrecht, and De Hoogstraat Rehabilitation, Utrecht, Netherlands,

³ Rijndam Rehabilitation Center, Rotterdam, Netherlands,

⁴ Department of Spinal Cord Injury Rehabilitation, Sint Maartenskliniek, Nijmegen, Netherlands,

⁵ Department of Orthopaedics, University Medical Center Utrecht, Utrecht, Netherlands,

⁶ AO Spine Knowledge Forum Trauma and Infection, Davos, Switzerland,

⁷ Department of Orthopedics, Vancouver Spine Surgery Institute, University of British Columbia, Vancouver, Canada

Introduction: The AO Spine PROST (PROST) is a validated measure of health-related quality of life (HRQoL) designed for use in individuals with spine trauma with no neurological deficit or incomplete spinal cord injury (SCI). For use in individuals with motor-complete traumatic or non-traumatic spinal cord disease (SCI/D), a slightly adapted PROST version 1.1 was developed. This multicenter study investigates the reliability and validity of the PROST 1.1 in people with longstanding motor-complete SCI/D. Material and Methods: Individuals with motor complete SCI/D were included. Internal consistency (Cronbach’s alpha), test-retest reliability (Intra-Class Correlations (ICC with 95% Confidence interval (CI)) and concurrent validity (Spearman correlations ≥ .50 with reference measures) were investigated. Results: A total of 72 participants were included (75% male, median age 54 (Inter-Quartile Range (IQR) 40-64) years, 63% ASIA Injury Severity grade A, 79% with paraplegia, median time since onset 20 (IQR 8-34) months of whom 62 also completed the second administration after a median of 7 (IQR 5-11) days. An approximately normal distribution without floor or ceiling effects was observed in the total PROST 1.1 score. Alpha was excellent (.90) and the ICC was good (.84; 95% CI .75-.90). Most correlations between the PROST 1.1 and the reference measures were strong (≥ .50) as expected, ranging from .27 with the VAS-score of the EuroQoL 5D-5L up to .70 with the sum-score of the EuroQoL 5D-5L. Conclusion: The slightly adapted AO Spine PROST (version 1.1) appears to be applicable in people with motor-complete SCI to evaluate their HRQoL. Treating surgeons are encouraged to use the PROST in the clinical setting and research to contribute to further evidence-based and patient-centered spine trauma care.

ID: 1881

A004: Outcome of early vs late traumatic spine fixation: a debate

Sabir Khan Khattak ¹

¹ Ghurki Trust & Teaching Hospital, Orthopedic and Spine Center, Lahore, Pakistan

Introduction: The timing of spinal fixation in injuries is debated, with early fixation promoting quicker recovery and late fixation reserved for certain cases. There is limited consensus on the best approach, particularly in Asia, where patient profiles and healthcare resources vary. Our objective is to compare the impact of early surgery and delayed spine fixation surgery on the patient's outcome in terms of neurology, hospital stay, ICU stay in the tertiary care hospital, Lahore. Material and Methods: A non-randomized retrospective study was conducted at the Department of Orthopedics & Spine Centre, Ghurki Trust Teaching Hospital, Lahore. 200 Patients meeting appropriate inclusion criteria were divided into an early or a late surgical treatment group. The neurologic outcomes, Time to surgery, hospital stay, ICU stay and post-operative complications were evaluated. Results: A total of 200 patients were included in the study; the majority were male cases as compared to female cases with 42.7 ± 15.2 ranging from 20 to 75 years, with 75 (37.5%) in the early surgery group and 125 (62.5%) in the delayed surgery group. Among them, 85 (42.5%) had thoracic fractures, 100 (50%) had lumbar fractures, and 15 (7.5%) had cervical fractures. Baseline characteristics between the groups were similar. Patients who underwent early surgical stabilization experienced significantly shorter intubation times, ICU length of stay (ICU-LOS), and overall hospital length of stay (LOS) compared to those in the delayed surgery group. There is significant improvement in neurology on ASIA impairment scale (AIS) observed in patients treated early after 6 months follow up as compared to delayed group. The mortality rate was 5% in the early surgery group and 11% in the late surgery group in cervical trauma patients. The most benefited of early surgery were of those who had thoracic spine injury with recovering of AIS from type C & D to E. In this subgroup of patients, those treated within the first 72 h had shorter mechanical ventilation time than those operated after the first 72 h. Conclusion: There is no reason to delay surgery, as the outcomes in the early surgery group are significantly better compared to the delayed group. Early surgical stabilization results in shorter intubation times, ICU stays, and hospital stays, with marked improvements in neurology in term of ASIA impairment scale, particularly in patients with thoracic spine injuries. The findings clearly show that early intervention leads to better patient outcomes, making it the preferred approach over delayed surgery.

ID: 1027

A005: Acute traumatic sub-axial central cord syndrome: can delaying surgery causes disaster?

Sharif Ahmed Jonayed ¹

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

Introduction: Traumatic central cord syndrome (TCCS) is an incomplete spinal cord injury defined by greater weakness in upper versus lower extremities, variable sensory loss, and variable bladder, bowel, and sexual dysfunction. The optimal timing of surgery for TCCS remains controversial. Objective: The purpose of this study was to evaluate whether timing of surgery for TCCS predicts neurological outcomes, length of stay, and complications. Methods: Forty-two patients with TCCS without fracture or dislocation were identified and divided into two groups described as two groups i.e. early surgery and delayed surgery group. Clinical outcomes including ASIA Motor Score (AMS), Japanese Orthopaedic Association (JOA) score upon admission and follow-up, change in AMS, and JOA recovery rate were analyzed. Logistic regression analysis was performed to show the correlation between timing of surgery and clinical outcomes. Results: All patients received a minimum of 1-year follow-up and showed significant neurological recovery at the final follow-up. No statistical differences in final AMS and JOA scores were observed between the two groups. There is insufficient evidence that lengths of hospital or intensive care unit stay differ between patients who undergo early versus delayed surgery. Furthermore, there is insufficient evidence that timing between injury and surgery predicts mortality rates or serious or minor adverse events. Conclusion: Surgery for TCCS,24 hours after injury appears safe and effective. Although there is insufficient evidence to provide a clear recommendation for early surgery (24 hours), it is preferable to operate during the first hospital admission and within 2 weeks after injury.

ID: 1542

A006: Patients with traumatic spinal injuries treated in a low-middle income country: what happens after discharge?

Chibuikem Ikwuegbuenyi ¹ , Tyler Zeoli ² , Francois Waterkeyn ³ , Consolata Shayo ⁴ , Julieth Joseph ⁴ , Rahel Mwavika ⁵ , Hiten Solanki ⁴ , Arthur Okembo ⁴ , Julie Woodfield ⁶ , Ibrahim Hussain ¹ , Hamisi Shabani ⁴ , Halinder Mangat ⁷ , Scott Lawrence Zuckerman ^2,8 , Roger Härtl ¹

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

² Vanderbilt University Medical Center, Department of Neurological Surgery, Nashville, United States,

³ Grand Hôpital de Charleroi, Department of Neurosciences, Charleroi, Belgium,

⁴ Muhimbili Orthopedic and Neurosurgery Institute, Division of Neurosurgery, Dar es Salam, Tanzania,

⁵ Muhimbili Orthopaedic Institute, Division of Orthopaedics, Dar es Salam, Tanzania,

⁶ University of Edinburgh, Centre for Clinical Brain Sciences, Edinburgh, United Kingdom,

⁷ Kansas University Medical Center, Department of Neurology, Kansas City, United States,

⁸ Vanderbilt University of Medical Center, Department of Orthopedic, Nashville, United States

Introduction: Traumatic spinal injuries (TSI) represent significant global health challenges, particularly in low- and middle-income countries (LMICs). In a cohort of patients suffering TSI from a major East Africa center, we sought to address long-term outcomes after hospital discharge through the following objectives: a) describe who was successfully contacted post-hospital, b) report post-hospital complications, and c) assess predictors of successful post-hospital contact, and post-hospital complications. Material and Methods: A retrospective cohort 2016-2021 from an institutional TSI registry was the source of patients and contact methods. Telephone calls were made to the primary telephone number between 06/2022 and 04/2023, and a subjective neurological assessment was performed using a questionnaire. Our outcomes were successful post-hospital contact and post-discharge complications. Predictors of each outcome were assessed through univariable/multivariable logistic regression. Results: Of the 466 TSI patients treated from 2016-2021, 40.6% were successfully contacted at a median follow-up period of 29 months. The median age was 34 years, with most patients being male (85.8%). Among those contacted, 84.8% experienced post-discharge complications, including muscle spasticity (61.4%), pressure ulcers (35.9%), and mortality (21.2%). Most patients reported a perceived improvement in their neurological status. Key factors predicting successful contact included undergoing surgery, involvement in road traffic accidents (RTAs), and more recent hospital admission dates following TSI (2019-2021). Employment post-injury was associated with fewer complications (OR 0.20, 95% CI 0.04-0.76). AIS-A at discharge was associated with a significantly increased mortality risk compared to AIS B-E (OR 15.58, 95% CI 5.80-50.46, p < 0.001). Conclusion: This is one of few studies to report on post-hospital follow-up using telephone contact for TSI in an LMIC. Among the contactable patients, there were high rates of morbidity and mortality and low rates of employment, showing the considerable medical, social, and economic impact of TSI in this young population and the need for rehabilitation and support services post-discharge.

ID: 21

A007: Vertebral fracture incidence and risk factors following liver transplantation: tertiary transplant center experience

Fawaz Alshaalan ¹ , Faisal Konbaz ¹ , Anouar Bourghli ¹ , Khaled Almusrea ¹

¹ King Faisal Specialist Hospital and Research Center, Spine Surgery, Riyadh, Saudi Arabia

Introduction: Solid organ transplant is considered an established treatment that improves the longevity and quality of life in end-organ failure patients, with liver being one of the most common transplanted organs. Post-transplantation bone disease has been established as a common consequence of solid organ transplant. This study aims to assess the incidence and risk factors of vertebral compression fractures following liver transplant surgery in a tertiary transplant care center. Material and Methods: A retrospective electronic audit included all patients undergoing liver transplant surgery at King Faisal Specialist Hospital and Research Center (KFSHRC), Riyadh, Saudi Arabia, from 2016 to 2020, with at least 3 years of follow-up. Pre- and Post-transplant Data were collected. The Kaplan–Meier statistic was used to estimate the cumulative incidence of fractures. Statistical significance was determined by two-tailed p-values < 0.05. Results: 434 patients were included in the audit, with a mean follow-up of 46.5 months. Vertebral fracture incidence was 8.3%, with most being at the thoracolumbar junction. The first-year post-transplant recorded the highest rate of fracture incidence with a mean of 10.5 months. Most patients were either osteoporotic or osteopenic pre- and post-transplant. The utilization of bone protective medications was low pre- and post-transplant, at 11% and 18%, respectively. The mean duration of glucocorticoid use was 26 months. Post-transplant use and duration of prednisolone and other immunosuppressant medications showed no significant association with fracture incidence. Pre-transplant osteoporosis was predictive for vertebral fracture post-transplant (p = 0.011). Conclusion: Our audit reveals a higher incidence of vertebral compression fractures following liver transplant compared to recently published data. The risk seems to be highest soon after transplant. Post-transplantation bone disease prevention should focus on optimizing bone mass prior to transplantation and preventing bone loss in the early postoperative period.

ID: 2772

A008: Symptomatic pars defect repair by intra-laminar screws and bone graft

Kamrul Ahsan ¹

¹ Bangladesh Sheikh Mujib Medical University (BSMMU), Orthopaedic Surgery, Dhaka, Bangladesh

Introduction: Out of wide range of surgical techniques direct repair techniques are emphasized to avoid fusion related complications in pars defects. To assess the clinical, functional and radiological outcome of direct operative repair of pars defects by intra-laminar screws and bone graft. Material and Methods: This retrospective study was done in Bangabandhu Sheikh Mujib Medical University and in our private settings, within the period of July 2005 to December 2022. Records of 36 patients (age range, 21-35 years) with symptomatic pars defect, 21 men and 15 women (mean 28 years) who underwent direct pars repair with intralaminar screws and bone graft were reviewed. The surgical time, intra-operative blood loss, post-operative hospital stays and time to achieve union was recorded. Self-evaluated back pain using VAS and ODI was analyzed. Clinical outcome was assessed using Modified Prolo Scale, Radiological fusion using Shin criteria, restoration of total lumbar lordosis (TLL) and overall functional outcome using Odom's Criteria was calculated. Chi-squared test and paired-t test were used for statistical analysis using SPSS. Results: The VAS, ODI and clinical outcome had significant (p < 0.05) improvement as had the radiological fusion and TLL. Overall satisfactory outcome was achieved in 91.67% cases. Despite of no intra-operative or post-operative complications, pseudarthrosis developed in 02 case which could be managed conservatively. Conclusion: Direct repair of pars defect with intra-laminar screws and bone graft is satisfactory in properly selected cases.

ID: 839

A009: Retrospective analysis of fall characteristics in pre-COVID and post-COVID eras: a comparative study between patients under 65 and over 65 in a major trauma hospital in London

Shruthi Atapaka ¹ , Zion Hwang ² , Liam Rose ² , James Geddes ² , Adnan Sheikh ² , Hasan Raza ² , Tesfaladet Kurban ² , Timothy Bishop ² , Bisola Ajayi ² , Jason Bernard ² , Rhys Owen ¹ , Mak Macapagal ¹ , Deepshika Varasala ¹ , Nawal Siddiqui ¹ , Jack Williams ¹ , Paavan Shah ¹ , Charles Taylor ² , Darren Lui ²

¹ St. George's, University of London, London, United Kingdom,

² St. George's hospital , London, United Kingdom

Introduction: Falls are a leading cause of morbidity and mortality, particularly in older adults, and frequently cause spinal injuries. Major trauma is defined as an Injury Severity Score (ISS) >15, with falls representing a significant portion of these high-severity presentations. Spinal injuries due to falls often involve polytrauma and carry a high injury severity profile. The COVID-19 pandemic might have influenced fall patterns, particularly spinal trauma, due to changes in social support, mobility, and mental health. This study compares spinal trauma resulting from falls among patients under 65 and over 65 in pre-COVID and post-COVID periods at a London Major Trauma Centre. Material and Methods: This retrospective analysis examined spine trauma patients admitted between 2017-2022 following falls. The study period was divided into pre-COVID (2017-2019) and post-COVID (2020-2022). 2017, 2020, and 2021 were selected for focused analysis to establish a pre-COVID baseline (2017) and capture the immediate pandemic’s impact (2020-2021) on fall-related spinal trauma patterns and outcomes. Patient demographics, injury characteristics, and outcomes were assessed, with a Chi-squared test used to evaluate significant differences. Results: Among 1549 spine trauma patients admitted between 2017-2022, 769 were fall-related, with 57.9% male, 42.1% female, and a mean age of 64.5 years. The average ISS was 19.6, with 50.3% of patients having an ISS > 15, and 58% presenting with polytrauma, highlighting the complexity of spinal injuries in fall-related trauma. Pre-COVID, younger patients (under 65) experienced more high-height falls (>15 feet) (21.4% in 2017) (p < 0.05), often resulting in severe spinal injuries, while older patients primarily suffered low-height falls (< 5 feet) (46.5% in 2017), which also led to significant spinal trauma due to their increased vulnerability. Post-COVID, high-height falls in younger patients decreased (15.0% in 2021), while low-height falls among older patients remained common (43.2% in 2021), underscoring continued risks for spinal injuries in this population. Polytrauma rates, including complex spinal injuries, rose significantly from 47% in 2017 to 60% in 2020 across both age groups (p < 0.05). The ISS in older patients initially decreased from 15.1 to 11.9 before spiking to 42 in 2021, corresponding with more severe spinal injuries. In younger patients, the ISS rose from 13.6 to 22 in 2020 and fell to 15.8 in 2021 (p < 0.05). The pandemic coincided with a 69% reduction in trauma cases among patients under 65 and a 45% decline in older patients, but the severity of spinal injuries increased in both groups. Mortality remained stable among younger patients (9.7% in 2017 vs. 9.1% in 2021), while mortality increased among older patients, from 30.2% in 2017 to 32.8% in 2021, reflecting the increased complexity of spinal trauma in this group. Conclusion: The COVID-19 pandemic has markedly influenced fall-related spinal trauma patterns, leading to an overall reduction in fall cases but an increase in spinal injury severity and polytrauma, particularly in patients over 65. Older adults consistently experienced high rates of low-height falls, contributing to serious spinal injuries, highlighting the need for targeted fall prevention strategies and enhanced support systems for this vulnerable population.

OP02: Degenerative Cervical Surgery 1

ID: 2949

A010: Posterior cervical foraminotomy compared with anterior cervical discectomy with fusion for cervical radiculopathy: two-year results of the FACET randomized noninferiority study

Nádia Simões de Souza ¹ , Anne Broekema ¹ , Michiel Reneman ¹ , Jan Koopmans ¹ , Henk van Santbrink ¹ , Mark Arts ¹ , Bachtiar Burhani ¹ , Niels van der Gaag ¹ , Martijn Verhagen ² , Katalin Tamasi ¹ , Marc van Dijk ¹ , Rob Groen ¹ , Remko Soer ¹ , Jos Kuijlen ¹

¹ University Medical Center Groningen, Groningen, Netherlands,

² Noordwest Ziekenhuisgroep, Alkmaar, Netherlands

Introduction: Posterior cervical foraminotomy (posterior surgery) is a valid alternative to anterior discectomy with fusion (anterior surgery) as a surgical treatment of cervical radiculopathy, but the quality of evidence has been limited. The purpose of this study was to compare the clinical outcome of these treatments after 2 years of follow-up. We hypothesized that posterior surgery would be noninferior to anterior surgery. Material and Methods: This multicenter, randomized, noninferiority trial assessed patients with single-level cervical radiculopathy in 9 Dutch hospitals with a follow-up duration of 2 years. The primary outcomes measured reduction of cervical radicular pain and were the success ratio based on the Odom criteria, and arm pain and decrease in arm pain, evaluated with the visual analog scale, with a 10% noninferiority margin, which represents the maximum acceptable difference between the new treatment (posterior surgery) and the standard treatment (anterior surgery), beyond which the new treatment would be considered clinically unacceptable. The secondary outcomes were neck pain, Neck Disability Index, Work Ability Index, quality of life, complications (including reoperations), and treatment satisfaction. Generalized linear mixed effects modeling was used for analyses. The study was registered at the Overview of Medical Research in the Netherlands (OMON), formerly the Netherlands Trial Register (NTR5536). Results: From January 2016 to May 2020, 265 patients were randomized (132 to the posterior surgery group and 133 to the anterior surgery group). Among these, 25 did not have the allocated intervention; 11 of these 25 patients had symptom improvement, and the rest of the patients did not have the intervention due to various reasons. At the 2-year follow-up, of 243 patients, primary outcome data were available for 236 patients (97%). Predicted proportions of a successful outcome were 0.81 after posterior surgery and 0.74 after anterior surgery (difference in rate, -0.06 [1-sided 95% confidence interval (CI), -0.02]), indicating the noninferiority of posterior surgery. The between-group difference in arm pain was -2.7 (1-sided 95% CI, 7.4) and the between-group difference in the decrease in arm pain was 1.5 (1-sided 95% CI, 8.2), both confirming the noninferiority of posterior surgery. The secondary outcomes demonstrated small between-group differences. Serious surgery-related adverse events occurred in 9 patients (8%) who underwent posterior surgery, including 9 reoperations, and 11 patients (9%) who underwent anterior surgery, including 7 reoperations (difference in reoperation rate, -0.02 [2-sided 95% CI, -0.09 to 0.05]). Conclusion: This trial demonstrated that, after a 2-year follow-up, posterior surgery was noninferior to anterior surgery with regard to the success rate and arm pain reduction in patients with cervical radiculopathy. Therapeutic Level I.

ID: 406

A011: Evaluating MRI-based vertebral bone quality as a predictor of cage subsidence following anterior cervical discectomy and fusion

Ara Khoylyan ¹ , Jason Salvato ¹ , Taylor Moglia 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 spine procedure to treat degenerative cervical conditions. A significant surgical complication is cage subsidence, which can result in loss of indirect decompression, deformity, recurrent neck pain and radicular symptoms. Cage subsidence can be influenced by patient factors such as age, medical history, and bone quality. Recent advancements in magnetic resonance imaging (MRI) have introduced the Vertebral Bone Quality (VBQ) score, an MRI-based measure of trabecular bone, offering a potentially more precise measure of bone quality. The primary objectives of this study are to determine the association between VBQ scores and subsidence after single-level ACDF and whether there is a clinically relevant cutoff that can be used to determine risk. We hypothesize that higher VBQ scores, which correlate with poorer bone quality, are associated with higher subsidence risk. Material and Methods: Retrospective review was performed identifying patients who underwent elective single-level ACDF procedure for degenerative pathology between November 2019 and April 2023. Exclusion criteria included non-degenerative diagnosis, prior revisions at the index level, multilevel procedures, anterior/posterior fusions, and corpectomies. VBQ was calculated at C2-C7 from pre-operative T1-weighted MRI images within one year of surgery. 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 117 patients undergoing ACDF were included. Moderate radiographic subsidence was present in 22 patients (19%), and severe subsidence was present in 3 patients (2%) post-operatively. Mean VBQ score was significantly higher in those with clinical subsidence than those without (2.2 vs. 2.7, p < .001). There was moderate correlation between VBQ score and clinical subsidence (R = 0.388, p < .001). Those with a higher VBQ demonstrated significantly higher odds of developing clinical subsidence post-operatively (OR = 14.59, 95% CI 1.64-128.58, p = .016). A VBQ score of 2.11 demonstrated 90% sensitivity and 38% specificity in detecting clinical cage subsidence. A VBQ score of 2.79 was 45% sensitive and 91% specific (AUC = 0.747, p < .001). There were no differences in one-year postoperative outcomes between those with and without clinical subsidence based on PROMIS (31.1 vs 29.6; p=.566) and NDI (32.3 vs 32.5; p = .984) scores. Conclusion: Patients with higher cervical VBQ scores are at a significantly greater risk of developing radiographic cage subsidence following single-level ACDF, with a VBQ cutoff of 2.11 demonstrating high sensitivity. Our findings further elucidate the utility of VBQ scores in cervical spine surgery and help guide pre-operative planning and patient counseling.

ID: 1978

A012: Differences in outcomes following circumferential cervical fusion at three levels compared to ACDF alone: an interim analysis of 12- and 24-month results from a prospective randomized IDE trial

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

¹ Thomas Jefferson University, Philadelphia, United States,

² Pinehurst Surgical Clinic, Pinehurst, United States,

³ Strenge Spine Center, Paducah, United States,

⁴ Premier Orthopaedic Associates, Vineland, United States,

⁵ Louisiana State University, New Orleans, United States,

⁶ Louisiana Spine Institute, Shreveport, 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: ACDF is the most common surgical treatment for degenerative conditions of the cervical spine. One of the greatest risks following ACDF is pseudoarthrosis, particularly when treating multiple levels. Including posterior supplemental fixation (circumferential cervical fusion, CCF) is one method to decrease the risk of pseudoarthrosis, however this introduces additional surgical burden, particularly when done with an open approach. The FUSE IDE clinical trial was designed to understand how CCF with a tissue-sparing posterior cervical stabilization system (PCSS) impacts clinical and radiographic outcomes when compared to ACDF alone. Material and Methods: Subjects were randomized 1:1 to ACDF alone -or- CCF with PCSS. All had symptoms resulting from degenerative discs at 3 levels. The primary endpoint was fusion at 12 months. The secondary endpoint was a composite safety outcome assessed at 24 months and was dependent on fusion, improvement in NDI, absence of surgical revision, and maintenance/improvement in neurological status. Fusion was assessed by an independent imaging lab with success defined as all treated segments exhibiting a range of motion < 2 with evidence of bridging bone across the interbody space. Meaningful improvement in NDI was defined as 15+ improvement if baseline was ≥ 30 or 50+% improvement if baseline was < 30. Neurological success was defined as maintenance or improvement in neurological assessment compared to baseline. Results: At the time of this interim analysis, 202 subjects (58 ± 9 years, 59% female) contributed to 12-month outcomes and 116 subjects (58 ± 10 years, 57% female) to 24-month outcomes. At 12 months, CCF had a higher percentage of subjects with fusion when compared to ACDF (CCF = 61.0%, ACDF = 16.7%, p < 0.001). At 24 months, CCF exhibited higher rates of composite safety success when compared to ACDF (CCF = 50.8%, ACDF = 22.8%, p = 0.002). Observed differences in composite safety success at 24 months were largely driven by differences in fusion (CCF = 74.6%, ACDF = 33.3%, p < 0.001) and incidence of subsequent surgical intervention (CCF = 1.7%, ACDF = 22.8%, p = 0.002). Improvement in NDI was recorded in 69.6% of CCF and 57.7% of ACDF (p = 0.196). Neurological success was achieved in 93.0% of CCF and 96.1% of ACDF (p = 0.682). Conclusion: Subjects receiving CCF with PCSS had superior radiographic and safety outcomes when compared to ACDF only for the treatment of 3-level disease. The observed rate of revision in the ACDF only group suggests the risk of symptomatic pseudoarthrosis in 3+ level treatment may be greater than what is currently reported and that supplemental fixation with PCSS mitigates this risk.

ID: 570

A013: Novel anterior approach to the cervical spine: an operative technique

Germain Sophie Ngana ¹ , Zain Nassrullah ¹ , Suhail AlAssiri ² , Abdulaziz Al-Zailaie ² , Geofrey Ngetich ² , Desmond Kwok ³ , Markian Pahuta ³ , Amanda Martinyuk ⁴ , Daipayan Guha ⁴

¹ McMaster University, Michael G. DeGroote School of Medicine, Hamilton, Canada,

² Hamilton Health Sciences, Spine Surgery, Hamilton, Canada,

³ McMaster University, Department of Surgery, Division of Orthopedic Surgery, Hamilton, Canada,

⁴ McMaster University, Department of Surgery, Division of Neurosurgery, Hamilton, Canada

Introduction: Among anterior approaches to the cervical spine the Smith-Robinson, or anterolateral approach is most commonly used by neurosurgeons and orthopedic surgeons to expose vertebrae in the context of discectomy/fusion, arthroplasty, or corpectomy. However, postoperative dysphagia, associated with extended and continuous retraction of the esophagus, remains a significant complication. Here we describe an alternative paramedian strap-splitting approach that provides a direct window to the cervical spine while requiring less retraction of midline structures compared to the more lateral Smith-Robinson approach. Material and Methods: Using a cadaveric model, we demonstrate both the standard anterolateral Smith-Robinson approach and the paramedian strap-splitting approach for anterior cervical exposure. Results: Our cadaveric study presents a detailed, step-by-step guide for executing the strap-splitting approach and highlights its advantages over the standard Smith-Robinson approach in terms of reduced retraction and more direct midline trajectory to the spine. Conclusion: Our comparison of these approaches provides a comprehensive understanding of the surgical anatomy necessary for the strap-splitting approach in anterior cervical spine surgeries as an alternative to the standard Smith-Robinson approach. This strap-splitting method develops a plane between the tracheoesophageal bundle medially and the infrahyoid strap muscles laterally, providing a greater margin of safety from the carotid sheath. Unlike the more lateral Smith-Robinson approach, the strap-splitting technique aligns more directly with the midline, minimizing the retraction of and potential traction injury to midline structures. This in turn may reduce intraoperative pressure on the esophagus and theoretically decrease the incidence of postoperative dysphagia, one of the most common complications of anterior spinal surgery. This detailed description of the strap-splitting approach, not previously described in the literature, provides surgeons with a viable and more direct alternative for anterior cervical spine surgeries. Clinical data is required to quantify the comparative safety and efficiency of this approach.

ID: 2291

A014: Postoperative outcomes of cervical decompression surgery without fusion in patients with cervical spondylotic myelopathy with predominant neck pain

Hiroyuki Nakarai ¹ , So Kato ¹ , Yasushi Oshima ¹

¹ The University of Tokyo Hospital, Department of Orthopaedic Surgery, Tokyo, Japan

Introduction: Neck pain (NP) is a frequently observed manifestation in patients with cervical spondylotic myelopathy (CSM). Although it has been suggested that improvement in myelopathy may relieve concurrent NP directly or indirectly, surgeons may be more inclined to perform fusion surgery rather than decompression surgery in patients with predominant neck pain (pNP) than in patients with non-predominant neck pain (npNP), namely predominant upper extremity pain. However, there is a lack of evidence regarding the impact of pNP on the outcome of cervical decompression surgery without fusion. The objective of this study was to evaluate the outcomes of decompression surgery in CSM patients with pNP. Material and Methods: This is a multicenter retrospective cohort study that utilizes a registry database of all spine surgeries performed at 13 tertiary referral hospitals. Patients with CSM who underwent primary laminoplasty or laminectomy without fusion between 2019 and 2022 with one-year postoperative follow-up were included. The Neck Disability Index (NDI) and the Japanese Orthopaedic Association (JOA) score, and Numerical Rating Scale (NRS) scores for NP and hand pain (HP) were collected. The pNP was defined as baseline NP greater than HP, while npNP was defined as HP greater than NP. A minimum clinically important difference (MCID) of 4.2 was used for the NDI, as previously reported. A comparison of patient backgrounds and pre-to-postoperative outcomes was conducted between patients with pNP and npNP. Inverse probability weighting (IPW) with propensity scores was applied to adjust for patient demographics and baseline NRS-NP. Results: A total of 554 patients (mean age 71 ± 11 years, 66% male) were analyzed. The mean baseline NRS-NP for the overall patient cohort was 2.4 ± 2.7, demonstrating a statistically significant improvement to 1.8 ± 2.2 postoperatively (p < 0.001). The proportion of patients with NRS-NP ≤ 3 was 73% preoperatively and increased to 82% postoperatively. However, only 44% of patients with baseline NRS-NP > 7 exhibited an improvement to NRS-NP ≤ 3 postoperatively. A total of 157 patients (28%) were classified as being in the pNP group. Patients with pNP were significantly younger (68.6 vs. 72.2 years old, p < .001) and exhibited better preoperative JOA scores (11.8 vs. 11.0, p = 0.01). However, no differences were observed in other demographic and surgical factors, including the number and levels of decompression between groups. Although postoperative NDI (26.7 vs 23.3, p = 0.04) and JOA recovery rate (7.1 vs 24.3%, p = 0.03) were significantly worse in pNP patients, the rate of MCID achievement was not significantly different (55 vs 50%, p = 0.35). After adjustment using IPW, the postoperative NDI, JOA score, and MCID achievement rate was not significantly different between groups. Conclusion: The baseline NP was significantly improved following cervical decompression surgery without fixation. Although there was a tendency for greater baseline NP to persist postoperatively, postoperative outcomes for CSM patients with pNP and npNP were found to be comparable.

ID: 202

A015: Leveraging small-sample machine learning for rigorous prediction of postoperative outcomes in cervical spondylotic myelopathy patients: insight from imaging parameters and modeling strategies

Zihe Feng ¹ , Honghao Yang ¹ , Zhangfu Li ¹ , Yong Hai ¹

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

Introduction: Degenerative Cervical Myelopathy (DCM) is a leading cause of spinal cord dysfunction, particularly in the aging population. Laminoplasty (LP) is a favored surgical treatment for its minimally invasive nature and preservation of joint mobility. However, postoperative complications such as axial pain and kyphosis remain significant concerns. Traditional prognostic studies focus on unchangeable factors, but recent research emphasizes the importance of modifiable biomechanical characteristics, including spinal sagittal alignment and paraspinal muscle condition. This study aims to leverage small-sample machine learning to enhance the prediction of postoperative outcomes in DCM patients, addressing the limitations of traditional statistical methods and exploring the potential of expert-informed feature engineering. Material and Methods: Data from 143 patients diagnosed with cervical spondylotic myelopathy (CSM) who underwent LP between January 2013 and December 2021 were analyzed. Patients were grouped based on postoperative outcomes using the Japanese Orthopedic Association (JOA) score recovery rate. The study employed two feature engineering strategies: Method 1 focused on cervical sagittal alignment parameters and paravertebral muscle cross-sectional area indices, while Method 2 incorporated these parameters along with fat infiltration levels. Machine learning algorithms, including Random Forest, XGBoost, Gaussian Naive Bayes, and Logistic Regression, were evaluated through grid search and 5-fold cross-validation. The dataset was divided into training and test sets, with multiple iterations of random partitioning to ensure robustness. Performance metrics such as sensitivity, specificity, accuracy, and AUC were used for evaluation. Results: Method 2, which included fat infiltration parameters, consistently outperformed Method 1 across multiple evaluation metrics. The Gaussian Naive Bayes algorithm achieved the best overall performance, with an accuracy of 76.90% and an AUC of 75.24%. Logistic regression and support vector machines also performed well but were slightly less accurate. Random forests showed high specificity but low sensitivity, suggesting a potential for missing high-risk patients. The study demonstrated that iterative sampling enhances metric stability and confidence intervals, indicating the robustness of the model performance evaluation. The results underscore the prognostic relevance of incorporating fat infiltration imaging parameters, allowing for more precise outcome predictions. Conclusion: This study demonstrates the efficacy of small-sample machine learning in predicting postoperative outcomes for CSM patients undergoing laminoplasty. By incorporating expert-informed feature engineering and multiple iterations, the study highlights the limitations of traditional statistical methods and showcases the potential of machine learning in clinical decision-making. The inclusion of fat infiltration parameters significantly enhances prognostic accuracy, with the Gaussian Naive Bayes algorithm showing the highest potential for clinical application. Despite some limitations, such as small sample size and lack of external validation, this research provides valuable insights into improving patient outcomes through advanced predictive modeling techniques.

ID: 869

A016: Case subsidence and long-term outcomes following standalone vs. cage-plate constructs in single-level anterior cervical discectomy and fusion

Taylor Moglia ¹ , Ara Khoylyan ¹ , Jason Salvato 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 spine procedure to treat refractory degenerative cervical conditions. Cage subsidence can occur following ACDF which can result in loss of indirect decompression, deformity, recurrent neck pain and radicular symptoms, and can be influenced by plate usage, bone quality, and cage material. The purpose of the study is to assess long term clinical outcomes and determine the association between standalone and cage-plate constructs, cage material, vertebral bone quality (VBQ) scores, and post-operative subsidence. Material and Methods: Retrospective analysis was performed identifying patients who underwent elective single-level ACDF for degenerative pathology between November 2019 and April 2023. Exclusion criteria included non-degenerative diagnoses such as trauma or infection, revision surgeries of the index level, multilevel ACDF procedures, and corpectomies. Radiographic subsidence was defined as a collapse of one-third or greater of the cage height. Cervical VBQ scores were measured to assess the relationship between bone density, subsidence, and fusion construct. Sub-group analysis was performed to assess differences in subsidence between cage materials. Descriptive and inferential statistics were performed. Results: 117 patients undergoing ACDF were included. Radiographic subsidence was present in 22 patients (19%). The subsidence and no subsidence cohorts had equal rates of plate usage (58% vs. 59%, p = 0.918). There was no difference in utilization of PEEK, titanium, or structural allograft cages between the two cohorts (p = 0.692). There were no differences in rate of subsidence between plate and standalone constructs in all three material groups on individual sub-group analysis (PEEK 82% vs 79%, p = 0.778; Titanium 80% vs 81%, p = 0.980; Allograft 81% vs. 100%, p = 0.672). VBQ score was positively associated with plate presence and patients with plate constructs had higher mean scores (r = 0.230, p = 0.017; 2.16 vs. 2.40, p = 0.017). VBQ scores were also significantly associated with increased risk of subsidence (O.R. 18.9, p < 0.001). Patients with cage-plate constructs demonstrated significantly lower Neck Disability Index (NDI) scores at 1 year completed to the standalone cohort (27.1 vs 38.9, p = 0.044). Conclusion: Both single-level standalone and cage-plate ACDF constructs demonstrated similar rates of post-operative radiographic subsidence. Cage-plate constructs are not shown to be protective of subsidence for patients with higher VBQ scores and poor bone quality. Subsidence rates were similar for PEEK, titanium, and structural allograft cages. Patients with single level cage-plate constructs demonstrated significantly better long term outcome scores, suggesting biomechanical differences in the standalone construct design which may lead to segmental micro-instability and eventual pseudarthrosis.

ID: 1673

A017: Novel radiologic parameter for assessing decompression adequacy in anterior cervical decompression surgery: the V-line

Sung Tan Cho ¹ , Dong-Ho Lee ² , Sehan Park ² , Jooyoung Lee ³

¹ Seoul Seonam Hospital, Seoul, Souh Korea,

² Asan medical center, Seoul, Souh Korea,

³ Dong-A Medical Center, Busan, Souh Korea

Introduction: Anterior cervical decompression surgeries, such as Vertebral Body Sliding Osteotomy (VBSO) and Anterior Cervical Corpectomy and Fusion (ACCF), serve as vital surgical options for managing cervical myelopathy. Despite their effectiveness, incomplete expansion of the spinal canal can occur in certain cases. However, many patients still experience positive clinical outcomes after these surgeries, suggesting that assessing outcomes based solely on the lesion’s canal-occupying effect may be limited. In cases of anterior-based fusion surgery, changes in cervical alignment can occur postoperatively. Since traditional measures like the canal occupying ratio (COR) consider only the absolute size of the lesion, they may overlook improvements in clinical symptoms due to enhanced lordosis. This study introduces the V-line, a novel radiologic parameter, to universally evaluate decompression outcomes in these procedures. Material and Methods: This retrospective analysis encompassed 93 patients treated for cervical myelopathy due to ossification of the posterior longitudinal ligament through either VBSO (N = 76) or ACCF (N = 17). The V-line, defined on a plain lateral radiograph in the neutral position, connects the lowest point on the posterior margin of the vertebral body immediately above the osteotomy site to the highest point on the posterior margin immediately below it. The V-line classification was “V-line (-)” if the postoperative pathologic lesion contacted the V-line and “V-line (+)” if it did not. Patients were categorized based on postoperative COR and the V-line assessment. Radiological evaluations included C2–7 lordosis, segmental lordosis, and COR. The Japanese Orthopedic Association (JOA) scores were assessed preoperatively, at 1-year postoperatively, and at the final follow-up. Results: The V-line (+) group achieved a higher final JOA score (15.3 ± 1.91) and JOA recovery rate (62.16 ± 32.22) compared to the V-line (-) group, which recorded a final JOA score (14.25 ± 2.33, p = 0.037) and a JOA recovery rate (24.71 ± 32.00, p < 0.001). Additionally, postoperative C2-7 lordosis (18.05 ± 9.59, p < 0.001) and segmental lordosis (18.53 ± 8.49, p = 0.008) in the V-line (+) group were significantly greater than in the V-line (-) group (10.68 ± 8.38; 11.42 ± 7.87). However, when comparing groups based on postoperative COR, significant differences were observed only in the JOA recovery rate, with no notable differences in final JOA score, C2-7 lordosis and segmental lordosis between the groups. Conclusion: Since the V-line accounts for both the mass effect of the pathological lesion and cervical alignment, this parameter effectively reflects the reduced impact of spinal cord compression when cervical lordosis is restored, even with residual canal-occupying lesions present. These findings underscore the importance of considering changes in alignment, not just the reduction in lesion size, in assessing decompression adequacy. Therefore, the V-line provides a more comprehensive measure of decompression adequacy than the traditional COR, which may fail to capture the clinical significance of changes in postoperative spinal alignment.

Keywords: V-line, Vertebral Body Sliding Osteotomy, Anterior Cervical Corpectomy and Fusion, decompression surgery, cervical myelopathy

ID: 1562

A018: Anterior cervical discectomy and fusion and carpal tunnel release surgery: a retrospective analysis

Ignacio Garcia Fleury¹, Catherine Olinger¹, Reagan Grieser-Yoder¹

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.

OP03: Spinal Oncology 1

ID: 1608

A019: Development of a Spine Cancer-Related Pain Classification

Ori Barzilai ¹ , Marie-Laure Vial ² , Jorrit-Jan Verlaan ³ , Joost Rutges ⁴ , Dean Chou ⁵ , Michelle Clarke ⁶ , Cordula Netzer ⁷ , Mohammed Karim ⁶ , Nicolas Dea ⁸ , Hanbo Chen ⁹ , John O'Toole ¹⁰ , Raphaële Charest-Morin ⁸ , Sheng-Fu Larry Lo ¹¹ , Daniel Lubelski ¹² , Charles Fisher ⁸ , Lisa Doan ¹³ , Michael Weber ¹⁴ , Ilya Laufer ¹³

¹ Memorial Sloan Kettering Cancer Center, New York, NY, USA, New York, United States,

² AO Foundation , Davos, Switzerland,

³ UMC Utrecht, Utrecht, Netherlands,

⁴ Erasmus MC, Rotterdam, Netherlands,

⁵ Columbia University Irving Medical Center, New York, NY, USA, New York, United States,

⁶ Mayo Clinic Comprehensive Cancer Center, Rochester, Rochester, United States,

⁷ Universitätsspital Basel, Basel, Switzerland,

⁸ The University of British Columbia, Vancouver, BC, Canada, Vancouver, Canada,

⁹ Sunnybrook Health Sciences Centre, Toronto, Canada,

¹⁰ Rush University Medical Center, Chicago, United States,

¹¹ Northwell Health Neurosurgery, Great Neck, NY, United States,

¹² Johns Hopkins University School of Medicine, Baltimore, MD, USA, Baltimore, United States,

¹³ New York University Langone Health, New York, New York, United States,

¹⁴ McGill University, Montreal, QC, Canada, Montreal, Canada

Introduction: Pain affects up to 66% of cancer patients, with spine being the most common site of cancer pain. Spine tumor pain serves as the most common symptom and treatment indication for patients with spinal metastatic tumors. A large proportion of patients continue to experience significant pain after spine tumor-directed treatment. A systematic literature review of the key pain states associated with spinal tumors identified significant knowledge gaps in spine tumor-specific taxonomy, assessment, and treatment recommendations. The objective of this study is to generate a core set of spine tumor descriptors and develop a mechanism-driven classification system for systematic pain assessment, treatment selection and focused pain experience measurement. This study was conducted on behalf of the AO Spine Knowledge Forum Tumor. Material and Methods: A modified Delphi process was conducted among 66 participants including 62 AO Spine Knowledge Forum Tumor members (neurosurgeons, orthopedic surgeons, radiation oncologists) and 3 pain anesthesiologists and 1 physiatrist. Three survey rounds were followed by a structured virtual summary meeting. Consensus at a minimum threshold of 75% participant agreement was predefined. Results: The initial survey included six categories, each with various subcategories 1) demographics included: age, sex, race, occupation, education and employment status; 2) pain characteristics included: location, temporal characteristics, pain severity, pain duration, pain quality and response to treatment; 3) psychosocial factors included: cognitive, emotional, behavioral, social and education; 4) clinical exam included: findings over the pain site, range of motion, posture change, weight bearing, Lasegue test, Ely’s (Duncan-Ely) test, Spurling test, “heel drop” test, Kemp test, sacroiliac provocation tests, paravertebral trigger points, presence of myelopathy; 5) diagnostic tests included: Imaging, EMG/NCS, diagnostic injection; and 6) medical comorbidities included: obesity, anxiety/depression, extent of cancer, smoking, spinal cord injury and pre-existing chronic pain diagnosis. To better understand important relations between mechanisms and descriptors, several yes/no questions were added to each round to achieve consensus. Consensus was reached for three categories necessary to comprehensively describe and differentiate types of spine cancer-related pain based on pain generation mechanism. The core classification includes location, pain descriptors and radiographic findings. Additional important variables helpful in guiding treatment decisions were included as modifiers. Conclusion: Expert consensus was reached regarding the key spine tumor pain assessment elements and a classification system was developed. This will provide the foundation for systematic evaluation and reporting of spine cancer-related pain and facilitate research and therapeutic decisions.

ID: 2402

A020: Intra-operative salvaged blood transfusion in metastatic spine tumour surgery: a propensity-score group matched analysis

Si Jian Hui ¹ , Naresh Kumar ¹ , Yiong Huak Chan ² , Yong Hao Tan ¹ , Aye Sander Zaw ¹ , Praveen Jeyachandran ² , Laranya Kumar ¹ , James Hallinan ¹ , Jiong Hao Tan ¹

¹ National University Health System, Singapore, Singapore,

² National University of Singapore, Singapore, Singapore

Purpose: Blood loss is an important consideration in metastatic spine tumour surgery (MSTS). Allogeneic blood transfusion (ABT) is the current standard of blood replenishment for MSTS despite known complications. Salvaged blood transfusion (SBT) through intraoperative cell salvage (IOCS) addresses majority of complications related to ABT. However, use of SBT in MSTS remains controversial. We conducted a prospective propensity-score (PS) matched analysis to evaluate the long-term clinical outcomes of IOCS in MSTS. Materials and Methods: Patients who underwent MSTS from 2014-2017 were included. PS matched cohort was created using the relevant and available predictors of treatment assignment and outcomes of interest. Clinical outcomes consisting of overall survival (OS), as well tumour progression (TP) that was evaluated using RECIST (v1.1) were analysed. Results: Our study included 98 patients with a mean age of 60 years old. 33 patients received SBT, 39 received ABT and 29 received NBT. Median blood loss was 400 mL [IQR 200-900 mL] and median BT was 328.5 mL (IQR: 0 - 1042 mL). Group PS matching included 30 patients who received ABT and 28 patients who received SBT. There was also no significant difference between the OS of patients who underwent ABT or SBT (p = 0.250, HR = 0.66, 95% CI 0.32-1.34). SBT did not show any significant increase in 4-year tumour progression (p = 0.908, unadjusted HR = 1.1, 95% CI 0.29-4.1). The incidence of both surgical and medical complications were consistent across both matched groups, showing no significant differences. Similarly, the duration of stay in the surgical high dependency (SHD) unit or intensive care unit (ICU), as well as the overall length of hospitalization, were comparable among both PS matched groups. Conclusion: SBT has shown to have similar clinical outcomes to that of ABT in patients undergoing MSTS, with benefits of avoiding complications of ABT. This is the first long term PS matched analysis reporting clinical outcomes of SBT, affirming its role in MSTS today.

Keywords: Metastatic spine tumour surgery, Salvaged blood, Blood transfusion, Allogenic blood, Intraoperative cell salvage

ID: 1996

A021: Voice of the customer: AO spine survey regarding spine oncology knowledge generation and translation needs preferences

Matthew Goodwin ¹ , Janneke Loomans ² , Ori Barzilai ³ , Nicolas Dea ⁴ , Alessandro Gasbarrini ⁵ , Cordula Netzer ⁶ , Jeremy Reynolds ⁷ , Laurence Rhines ⁸ , Arjun Sahgal ⁹ , Jorrit-Jan Verlaan ¹⁰ , Charles Fisher ¹¹ , Aron Lazary ¹² , Ilya Laufer ¹³ , on behalf of AO Spine Knowledge Forum Tumor

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

² AO Foundation, Davos Platz, Switzerland

³ Memorial Sloan-Kettering Cancer Center, New York, NY, United States

⁴ University of British Columbia, Combined Neurosurgical and Orthopedic Spine Program, Vancouver, BC, Canada

⁵ IRCCS Istituto Ortopedico Rizzoli, Bologna, Italy

⁶ Universitätsspital Basel, Basel, Switzerland

⁷ Oxford University Hospital NHS Trust, Oxford, United Kingdom

⁸ MD Anderson, Department of Neurosurgery, Houston, United States

⁹ Sunny Brook, Toronto, ON, Canada

¹⁰ UMC Utrecht, Utrecht, Netherlands

¹¹ University of British Columbia, Vancouver Spine Surgery Inst., Vancouver, BC, Canada

¹² National Center for Spinal Disorders, Budapest, Hungary

¹³ NYU Grossman School of Medicine, New York, NY, United States

Introduction: The management of both metastatic and primary spine tumors is a core responsibility of most spine surgeons. However, comfort and competency levels managing spinal tumors vary markedly, which is concerning. To better understand the current state of spine oncology knowledge, AO Spine members were surveyed about their comfort and competency in decision-making and surgical techniques necessary to treat patients with spine tumors, both column and cord. We also assessed their needs in spine oncology knowledge generation and translation both current and going forward. Material and Methods: An online needs assessment survey was distributed to all AO Spine members to gather general demographic information about the surgeons, as well as specific details on the volume and types of spine tumors they treat, and their comfort levels and knowledge of existing instruments for managing these tumors. The questions were presented in various formats, such as single and multiple-choice, open-ended, and Likert scale questions. Results: Three hundred and eighty-one providers (age 25 to 65+) from 82 countries completed the survey. Most respondents were either orthopedic spine surgeons (62%) or neurosurgeons (36%) performing 100-200 spine surgeries per year (42%). Most (84%) treated extradural primary tumors, with the largest group (55%) treating 1-5 cases per year. Less than half (38%) used systems to estimate survival or measure frailty. The majority (81%) felt comfortable deciding when emergency surgery was needed, but 78% found nuanced timing decisions challenging. While 68% felt comfortable with perioperative glucocorticoid use, questions about dosage and duration were common. Nearly all respondents (95%) treated metastatic extradural tumors, with 44% managing 6-20 cases per year. Most (80%) used a decision framework, with 69% using the NOMS framework. Nearly 70% used formal systems for evaluating epidural tumor extension, with 93% using the Bilsky ESCC score. While 61% assessed survival prognosis, only 43% assessed frailty. Most (82%) were comfortable determining emergency surgery needs, but 69% found subtle timing decisions challenging. Over 70% were comfortable with perioperative glucocorticoid use, but nearly 80% indicated guidelines on steroid administration would be useful. Nearly all respondents (92%) use SINS to assess tumor-related instability, highlighting its integration into clinical practice. While 51% used PROs, 74% were unaware of SOSGOQ2.0, and of those who were, only 50% used it. Less than half used the AO Surgery Reference. Respondents expressed a strong desire for guidelines on tumor-related spinal pain (85%), treatment timing (85%), stabilization (85%), and glucocorticoid use for symptomatic extradural metastatic tumors (77%). Most indicated they would likely use a classification system for spine tumor pain (65%) and for stabilization decisions (80%). Conclusion: The majority of respondents indicated they needed more support in decision-making, especially around timing of surgery, patient selection, and invasiveness related to life expectancy and frailty. Additional knowledge is needed around preventing neurologic deterioration and optimizing neurologic recovery. Guidelines and classification systems were highly coveted for daily practice.

ID: 1956

A022: Clinical outcomes of minimally invasive treatment for vertebral metastases: a retrospective multicenter study and comparison with literature

Alvaro Silva ^1,2 , Andres Lisoni ^1,2 , Ratko Yurac ¹ , Nicolás Rotman Hinzpeter ¹ , Ernesto Pino ³

¹ Clinica Alemana de Santiago - Universidad del Desarrollo, Spine Surgery, Santiago, Chile,

² Hospital Clínico de la Fuerza aérea de Chile, Spine Surgery, Santiago, Chile,

³ Clinica Alemana de Santiago - Universidad del Desarrollo, Traumatology and Orthopaedics, Santiago, Chile

Introduction: The aim of this study is to evaluate the clinical outcomes of a series of patients with vertebral metastases treated through minimally invasive fixation surgery, with or without epidural decompression. Material and Methods: This is a retrospective, descriptive, multicenter study. The clinical histories of 72 patients over 18 years old, who underwent surgery for vertebral metastases via percutaneous spinal stabilization, with or without minimally invasive epidural decompression, were reviewed. The minimum follow-up period was 3 months. Variables analyzed included demographics, origin and location of metastases, preoperative neurological status, type of surgery, postoperative changes in neurological status, and postoperative complications. Results: Patient demographics: 39 men, 33 women, mean age of 62 years. Type of metastases: Breast 26.4%, Lung 26.4%, Kidney 11.1%, Prostate 9.7%, Multiple Myeloma 6%, Colorectal 4.2%, Uterine 2.8%, Neuroendocrine 2.8%, Bladder 2.8%, Miscellaneous 5.6%, Double Cancer 1.4%, Unknown Origin 1.4%. Metastasis location: (T1-T6) 19.4%, (T7-T12) 44.4%, (L1-S1) 36.1%. Preoperative neurological status: ASIA E: 44 patients (61.1%), Isolated Radiculopathy: 8 patients (11.1%), Cauda Equina: 1 patient (1.4%), ASIA D: 9 patients (12.5%), ASIA C: 9 patients (12.5%), ASIA B: 1 patient (1.4%), ASIA A: 0%. Surgical approach: Fixation with percutaneous screws in 72 patients, epidural decompression (tumor separation surgery) in 35 patients (48.6%) (using tubular or “mini-open” midline surgery), and associated kyphoplasty to fixation in 21 patients (29.1%). Postoperative neurological status: ASIA E: 65 patients (90.3%), Isolated Radiculopathy (0%), Cauda Equina (0%), ASIA D: 5 patients (6.9%), ASIA C: 1 patient (1.4%), ASIA A: 1 patient (1.4%). Neurological status changes: 46 patients (63%) maintained their neurological status (44 ASIA E and 2 ASIA D), 25 patients (34.7%) improved (including those with radiculopathy and cauda equina), and 1 patient (1.4%) worsened from ASIA C to ASIA A (postoperative paraplegia interpreted as spinal ischemia). Postoperative complications: 10 patients (13.9%) experienced postoperative complications: wound dehiscence in 3 patients (4.2%), pneumonia in 2 patients (2.8%), epidural hematoma in 2 patients (2.8%) requiring surgical intervention, paraplegia in 1 patient (1.4%), urinary tract infection in 1 patient (1.4%), deep vein thrombosis in 1 patient (1.4%). There were no cases of wound infection (0%). By using the tumor separation technique at the spinal level and radicular decompression via a minimally invasive tubular or “mini-open” approach, along with percutaneous pedicle screw fixation, 27 out of 28 patients with neurological involvement improved their status, and only one worsened from ASIA C to ASIA A. These results are comparable to those observed with open decompression techniques. Furthermore, the complication rate was low and comparable to the literature, with a notable absence of postoperative infection, in contrast to open techniques where infection rates range from 10-24%, depending on the series. Conclusion: Minimally invasive treatment of vertebral metastases, consisting of percutaneous fixation with or without epidural decompression, appears to achieve comparable results to the open standard approach, with a lower complication rate.

ID: 2731

A023: Stereotactic radiosurgery for the treatment of spinal metastasis: a systematic review and meta-analysis with 2,209 patients

Filipe Ribeiro ¹ , Lucca Palavani ² , Marcelo Sousa ³ , Filipi Andreão ³ , Helvécio Filho ⁴ , Gabriel Simoni ⁵ , Ana Santos ⁶ , Anthony Hong ⁶ , Marcio Ferreira ⁷ , Thiago Scharth Montenegro ⁸ , Hérika Negri ⁹

¹ Barão de Mauá University Center, Faculty of Medicine, Ribeirão Preto, SP, Brazil, Ribeirão Preto, Brazil,

² Max Planck University Center, Indaiatuba, São Paulo, Brazil, Indaiatuba, Brazil,

³ Federal University of Rio de Janeiro, Rio de Janeiro, Brazil, Rio de Janeiro, Brazil,

⁴ Faculty of Medicine, University of Fortaleza, Fortaleza, Brazil, Fortaleza, Brazil,

⁵ University Center of Várzea Grande, Várzea Grande, Brazil,

⁶ School of Medicine, University of Costa Rica, San Pedro, San José, Costa Rica, San José, Costa Rica,

⁷ Department of Neurosurgery, Lenox Hill Hospital/Northwell Health, New York, NY, USA, New York, Brazil,

⁸ Michigan State University/Spectrum Health / MSU, Grand Rapids, United States,

⁹ Department of Neurosurgery, Mayo Clinic Hospital, Arizona, United States, Phoenix, United States

Introduction: Spinal metastases are the most prevalent tumors of the vertebral column, affecting up to 10% of cancer patients, with multiple lesions being the most commonly observed. Stereotactic radiosurgery is an established and effective therapeutic modality for the treatment of both brain and spinal metastases. However, there is a lack of robust evidence regarding the safety and efficacy of this procedure in various clinical contexts, such as spinal cord compression, progression-free survival (PFS), and Karnofsky status. A comprehensive meta-analysis could provide a clearer understanding of these aspects. Therefore, the objective of this study is to systematically evaluate the safety and efficacy of stereotactic radiosurgery in the treatment of spinal metastases, addressing the existing gaps in the literature. Methods: Following Cochrane and PRISMA guidelines, a search was performed in Medline, Embase, and Cochrane databases. Eligible studies included randomized or observational studies with ≥ 4 patients reporting on stereotactic radiosurgery for the treatment of spinal metastasis. A random-effects model was used to calculate a single-proportion analysis with 95% confidence intervals. Statistical analyses were performed using RStudio. Results: Thirty-seven studies involving 2,209 patients were selected. The progression-free survival rate (PFS) at 1 year was 79% (95% CI: 72 to 85), at 2 years was 73% (95% CI: 60 to 85), and at 3 years was 55% (95% CI: 37 to 73). 224 of 544 patients, 35% (95% CI: 14 to 58), demonstrated some neurological improvement. Spinal recurrence was observed in 18% (95% CI: 13 to 24) of cases. 14 of 252 patients experienced permanent postoperative deficits, 5% (95% CI: 2 to 9). The overall survival rate (OS) at 6 months was 66% (95% CI: 54 to 78), at 1 year was 56% (95% CI: 46 to 67), at 2 years was 51% (95% CI: 33 to 69), and at 3 years was 36% (95% CI: 30 to 42). Conclusion: Stereotactic radiosurgery is a safe and effective option for the treatment of spinal metastases. Future studies should take into account the primary lesion type and consider multiple variables, such as spinal stability, ambulatory status, prognosis, and Karnofsky performance status, to further refine treatment strategies and outcomes.

Keywords: Stereotactic radiosurgery; spinal metastasis; metastasis.

ID: 479

A024: CT-based 3D finite element analyses of pedicled tibia and fillet of thigh flap reconstruction for spinopelvic discontinuity after ischial-sparing external hemipelvectomy with sacrectomy

Ritika Menghani ¹ , Justin Bird ² , Karthik Tappa ² , Alex Mericli ² , Matthew Hanasono ² , Shalin Patel ² , Laurence Rhines ² , Patrick Lin ² , Valerae Lewis ² , Raudel Avila ¹

¹ Rice University, Houston, United States,

² MD Anderson Cancer Center, Houston, United States

Introduction: Spinopelvic discontinuity following external hemipelvectomy with sacrectomy presents significant challenges in both stability and function. Traditional reconstruction methods may not adequately restore biomechanical integrity, leading to compromised patient outcomes. A novel ischial-sparing, pedicled tibia and fillet of thigh flap technique has been developed to address this issue. However, the biomechanical stability of this reconstruction remains under explored. In this study, we analyzed 3D patient-specific spinopelvic models reconstructed from computed tomography (CT) data to understand the influence of relevant physiological loads on both pre- and post-reconstruction models. A high-fidelity 3D finite element (FE) model was used to simulate the spatial distribution of mechanical stresses within the reconstructed spinopelvic region, aiming to provide a detailed and systematic understanding of the critical stress distributions, load-bearing capacity, and further biomechanical implications of this innovative surgical technique. Material and Methods: A retrospective review was performed on all ischial-sparing spinopelvic resections and pedicled tibia reconstructions done between 2013 and 2024. CT data were de-identified and used to construct geometrically accurate in silico models of the spinopelvic complex, both pre- and post-reconstruction. A 3D finite element (FE) model based on linear elasticity was used to quantify the magnitude and spatial distribution of equivalent von Mises stresses resulting from bone displacements within the reconstructed pelvis, subjected to physiological forces ranging from 0 to 500 N to simulate real-life loading conditions during various activities. The Young’s modulus of the spinopelvic complex varied between 0.07 and 17 GPa, depending on bone type and density, while the Poisson’s ratio ranged from 0.2 to 0.4 for different bone types. The spinopelvic complex was meshed with 3D tetrahedral stress elements (C3D10M) and shell elements (STRI65) to model the material interfaces between cancellous and cortical bone. The total number of elements in the model ranged from approximately 180,000 (healthy) to 540,000 (reconstructed). Results: Eighteen cases were identified for review. Clinically, there were no tibia fractures. The FE analysis was initially performed on a representative reconstruction case. The simulation revealed high-stress concentrations within the reconstructed pelvis showing stress redistribution along the iliopectineal line and the sacrum that provide the loading paths under compressive loading. Overall, the stress distributions of the pedicled tibia reconstruction indicate successful restoration of the structural integrity. Furthermore, a comparison of the normalized stress distribution across three distinct reconstruction cases shows that the tibia provides superior biomechanical stability, with a stress ratio $\left(\frac{{\_}_T}{{\_}_{HP}}\sim 3\right)$ relative to the healthy pelvis ( ${\_}_{HP}$ ), compared to that of the femur $\left(\frac{{\_}_{FE}}{{\_}_{HP}}\sim 15\right)$ or fibula $\left(\frac{{\_}_{FI}}{{\_}_{HP}}\sim 13\right)$ . Conclusion: CT-based 3D FEA provides crucial insights into the biomechanical advantage of the pedicled tibia reconstruction for spinopelvic discontinuity. Compared to other graft options, the tibia offers a favorable balance between strength and adaptability, allowing for a reconstruction that not only restores structural stability but also mitigates the risk of future stress fractures. This biomechanical advantage, coupled with the observed clinical outcomes, supports the continued use and further refinement of this technique. Further research is essential to fully establish the long-term benefits and potential force loading limitations of this reconstruction method.

ID: 1517

A025: Proposal of a novel approach to graft fashioning for posterior column reconstruction after en bloc resection of primary spine tumors: the roof technique

Chiara Cini ¹ , Emanuela Asunis ¹ , Giovanni Barbanti Bròdano ¹ , Gisberto Evangelisti ¹ , valerio pipola ¹ , Marco Girolami ¹ , Giuseppe Tedesco ¹ , riccardo ghermandi ¹ , Stefano Bandiera ¹ , Silvia Terzi ¹ , Alessandro Gasbarrini ¹

¹ Istituto Ortopedico Rizzoli, Spine Surgery, Bologna, Italy

Introduction: Besides appropriate oncological principles for resection, spine tumors require complex reconstructive techniques in a setting of biologic compromise. Fusion outcomes in this cohort are influenced by several variables. Most previous studies focused more on the oncology related prognosis and only briefly reported on fusion rates and instrumentation failure. The aim of our study was to evaluate the efficacy of using bone graft for fusion across long posterior column defects after en bloc resection. Material and Methods: This retrospective observational study analyzed 30 patients with primary spinal tumors who underwent posterior column reconstruction after en bloc resections. In all cases, the resected anterior column was reconstructed with 3D-printed custom-made prosthesis, titanium mesh cages (TMC) or Polyetheretherketone/Carbon fiber (PEEK/CF) Vertebral Body Replacement (VBR). In regions where the posterior elements were completely resected, a structural fresh-frozen allograft or autologous bone graft was placed to span the defect and cover spinal cord. Fashioned bone graft was prepared with saddle cuts on its proximal and distal end to sit on the surface of the extremities of the spinous processes anchored to posterior instrumentation with sublaminar bands. Posterior fusion graft assessment was performed using CT scans with multiplanar reconstruction (MPRs) at 6 months, 12 months, and at the last follow-up. Fusion status was recorded according to four grades: complete fusion (cortical union of the structural allograft with central trabecular continuity), partial fusion (cortical union with partial trabecular incorporation), unipolar pseudarthrosis and bipolar pseudarthrosis (central trabecular discontinuity with superior or inferior cortical non-union, or both, along with a complete lack of central trabecular continuity, respectively). Results: The mean length of the graft was 10.01 ± 4.2 cm, and the mean construct spanned 6.7 ± 3.0 vertebral levels. Complete posterior graft fusion was achieved in 25 patients (83.3%) with a mean fusion time of 8.3 ± 2.1 months, while 5 patients (16.7%) achieved partial fusion with a mean time of 9.2 ± 2.1 months. Among the 9 patients who were treated with Proton Beam Therapy with a mean prescription dose of 50-54 Gy(RBE) in 25-27 fractions within 25 weeks from index surgery, complete fusion was observed in all cases at the last follow-up (38.6 ± 12.8 months). No significant difference in time to fusion was found compared to patients who did not undergo radiotherapy (7.3 vs 8.2 months, p = 0.070). All patients with PEEK/CF instrumentation (40% of the total) achieved complete fusion, with a mean fusion time of 6.2 ± 1.3 months. At the final follow-up (mean of 78 ± 2.3 months), no evidence of graft dislodgment or increased axial pain was found in our population. A rod fracture, without evidence of graft dislodgment, occurred only in one patient who underwent revision surgery at 20 months of follow-up. 3 (3%) patients experienced wound infections treated with DAIR approach without affecting the final fusion. Conclusion: This innovative technique of fashioning the graft posteriorly allows for both early and long-term stability with solid fusion. Additionally, in case of revision surgery for local recurrence, it avoids direct exposure of the spinal cord.

ID: 2225

A026: RAB3B dictates mTORC1/S6 signaling in chordoma and predicts response to mTORC1-targeted therapy

Jianxuan Gao ¹ , Dianwen Song ¹ , Ping Wang ² , Tong Meng ¹

¹ Department of Orthopedics, Shanghai Bone Tumor Institute, Shanghai General Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China,

² Tongji University Cancer Center, Shanghai Tenth People’s Hospital, School of Medicine, Tongji University, Shanghai, China

Introduction: Chordoma is a rare mesenchymal malignant tumor derived from notochord remnants, characterized by a high recurrence rate and poor prognosis. To date, its tumorigenic regulatory mechanisms remain unclear, and there is a lack of effective therapeutic targets and drug sensitivity markers. As a member of the Ras family GTPases, RAB3B has shown tumor-promoting effects in various cancers, but its role in chordoma remains undefined. This study aims to explore whether RAB3B regulates the occurrence and progression of chordoma through the mTORC1/rpS6 signaling pathway and whether RAB3B can serve as a potential predictive marker for mTORC1-targeted therapy. Material and Methods: We compared chordoma tissues with normal control tissues through transcriptomic and proteomic analyses to identify differentially expressed genes and proteins. Subsequently, we analyzed chromatin accessibility in chordoma cell lines and normal control cells using ATAC-seq and ChIP-seq technologies, identifying the transcriptional activity of differentially expressed genes. By knocking out the RAB3B gene using CRISPR-Cas9 technology, we further assessed its impact on the proliferation, migration, stemness maintenance, and tumorigenic capacity of chordoma cells both in vitro and in vivo. To investigate the specific regulatory mechanisms within signaling pathways, we utilized RNA-seq to analyze the effects of RAB3B knockout on key nodes of the PI3K-Akt-mTOR signaling pathway, and co-immunoprecipitation combined with mass spectrometry was used to validate the physical interactions between RAB3B, rpS6, and its dephosphorylating enzyme DUSP12. Finally, through drug intervention experiments using mTORC1 inhibitors (dactolisib and rapamycin) and clinical sample evaluation, we aim to clarify the predictive role of RAB3B in mTORC1-targeted therapy. Results: Transcriptomic and proteomic analyses revealed that RAB3B is significantly overexpressed in chordoma tissues. Tissue microarray and immunohistochemistry results further confirmed that the expression levels of RAB3B in chordoma patients are higher than in normal notochord tissues, and its expression positively correlates with malignant tumor phenotypes. Functional experiments demonstrated that RAB3B knockdown significantly reduced the proliferative capacity of chordoma cells, downregulated the expression of stemness maintenance markers, and notably decreased cell migration and tumorsphere formation abilities. Additionally, tumor growth was significantly inhibited in in vivo mouse models. Mechanistic studies showed that RAB3B regulates chordoma progression through the mTORC1 signaling pathway, particularly by specifically promoting the phosphorylation of rpS6 at the S235/236 site through its interaction with rpS6. Co-immunoprecipitation and mass spectrometry confirmed that RAB3B interacts with the dephosphorylating enzyme DUSP12, maintaining rpS6 activity by inhibiting DUSP12-mediated dephosphorylation of rpS6. RAB3B knockout led to a significant decrease in rpS6 phosphorylation at S235/236, thereby inhibiting the activation of the mTORC1 signaling pathway. Pharmacological experiments indicated that mTORC1 inhibitors (dactolisib and rapamycin) significantly suppressed the malignant phenotypes of chordoma cells with RAB3B overexpression and blocked rpS6 phosphorylation. Compared to cells expressing wild-type RAB3B, chordoma cells with RAB3B knockdown showed a significantly reduced response to mTORC1 inhibitors, suggesting that RAB3B may serve as a potential sensitivity marker for mTORC1-targeted therapy. Analysis of clinical chordoma patient samples revealed that patients with higher RAB3B and p-S6 (S235/236) expression levels had poorer prognoses but responded better to mTORC1 inhibitor treatments, indicating the potential of the RAB3B/p-S6 axis in predicting drug sensitivity. Conclusion: This study reveals that RAB3B is a novel activator of the mTORC1 signaling pathway and highlights the oncogenic and predictive roles of the RAB3B/p-S6 axis in chordoma. It suggests the therapeutic potential of mTORC1-targeted treatments for advanced chordoma patients with abnormal activation of RAB3B/p-S6.

ID: 230

A027: Safety and efficacy of tranexamic acid in oncologic surgery for spinal metastases: a systematic review and meta-analysis

Ali Haider Bangash ¹ , Jessica Ryvlin ¹ , Mitchell Fourman ¹ , Yaroslav Gelfand ¹ , Saikiran Murthy ¹ , Reza Yassari ¹ , Rafael De la Garza Ramos ¹

¹ Montefiore Einstein, Neurosurgery, New York, United States

Introduction: Tranexamic acid (TXA), an antifibrinolytic agent, has been shown to reduce blood loss and transfusion requirements in various surgical settings. However, its role in metastatic spinal tumor surgery remains unclear. The purpose of this study is to evaluate the safety and efficacy of tranexamic acid (TXA) in metastatic spine surgery through a systematic review and meta-analysis of primary studies. Material and Methods: A systematic review was conducted following PRISMA guidelines. Searches were performed in PubMed/Medline, Cochrane Database of Systematic Reviews, and Epistemonikos. Studies comparing TXA versus non-TXA outcomes in metastatic spine surgery published up until April 20, 2024 were included. The primary endpoint was added odds of adverse events/complications. The secondary endpoint was intraoperative blood loss. Tertiary endpoints included added odds of blood transfusion, number of packed red blood cells (PRBC) units transfused postoperatively, operating time, and postoperative blood loss. The study quality was assessed using the Methodological Index for Non-randomized Studies (MINORS) tool. Statistical analyses included odds ratio (OR) and inverse-variance random-effects model analysis to calculate standardized mean difference (SMD) and mean difference (MD) using RevMan and MedCalc software. Results: Three studies, including two case-control studies and one case series, met the inclusion criteria, comprising 354 patients with a mean age of 60 years and 51% (179 of 354) of female sex. For our primary endpoint, the analysis showed no significant difference in the odds of complications with TXA use compared to non-TXA group (OR 0.59 [95% CI 0.23 - 1.54]; p = 0.28). For the secondary endpoint, intraoperative blood loss was found to be significantly higher in the TXA group (SMD 0.248 [95% CI 0.023 to 0.474]; p = 0.03). For our tertiary endpoints, TXA was associated with increased odds of postoperative blood transfusion (OR 1.77 [95% confidence interval 1.04 to 3.01]; p = 0.04). The number of PRBC units transfused postoperatively, operating time or postoperative blood loss was not different between groups. Conclusion: The findings of this study suggest that based on the current best available evidence, the use of TXA in metastatic spine surgery does not increase the risk of complications. However, intraoperative blood loss and transfusion rates may be higher in cases involving TXA use. Further high-quality randomized trials are needed to clarify the role of TXA in this complex patient population.

OP04: Adult Deformity-Thoracolumbar 1

ID: 1184

A028: Analysis of the benefits and limitations conferred by the T1-pelvic-angle and the L1-pelvic-angle

Max Fisher ¹ , Ankita Das ¹ , Anthony Yung ¹ , Tobi Onafowokan ¹ , Tyler Williamson ² , Brett Rocos ¹ , Andrew Schoenfeld ³ , Zorica Buser ⁴ , D. Kojo Hamilton ⁵ , Nitin Agarwal ⁵ , Dean Chou ⁶ , Thomas Buell ⁵ , Nima Alan ⁷ , Michael Gerling ⁴ , Paul Park ⁸ , Andrew Chan ⁶ , Peter Passias ¹

¹ Duke University School of Medicine, Division of Spine Surgery, Departments of Orthopaedic and Neurological Surgery, Durham, United States,

² University of Texas Health Center at San Antonio, Department of Orthopaedic Surgery, San Antonio, United States,

³ Harvard Medical School, Department of Orthopaedic Surgery, Boston, United States,

⁴ Gerling Institute, New York, United States,

⁵ University of Pittsburgh School of Medicine, Department of Neurological Surgery, Pittsburgh, United States,

⁶ Columbia University, Department of Neurological Surgery, New York, United States,

⁷ University of California: San Francisco, Department of Neurosurgery, San Francisco, United States,

⁸ Semmes Murphy Clinic, Memphis, United States

Introduction: The T1-Pelvic-Angle (T1PA) provides a consistent global measure of sagittal alignment independent of compensatory mechanisms and positional changes. The L1-Pelvic-Angle (L1PA) is a different measure of sagittal alignment that can be similarly employed. However, these sagittal alignment measures may not explicitly inform alignment goals that correlate with a lower complication risk. This study assesses the value of T1PA/L1PA in delineating sagittal alignment goals across the ASD population. Material and Methods: Operative ASD patients ≥ 18 years with complete baseline (BL) and at least two-year (2Y) operative, radiographic, and health-related quality of life data were included. The primary outcome was development of mechanical complications. Cohorts were based on postoperative T1PA (T1PA < 10° or > 30° = unfavorable vs. T1PA 10°-30° = favorable) and L1PA (L1PA = Theoretical L1PA ± 5°: ideal vs. L1PA≠Theoretical L1PA ± 5°: non-ideal). Theoretical L1PA = 0.5x(Pelvic Incidence)-21°. Adjustments for confounders with separate analyses were done with multivariable logistic regressions. Results: 596 patients met inclusion criteria (mean age: 61.5 ± 13.4, 78.8% female, mean BMI: 27.8 8 ± 5.9 kg/m2, mean co-morbidity index: 1.9 ± 1.8). Postoperatively, 390 (67.1%) patients had favorable T1PAs, and 191 (32.9%) did not. 361 patients (60.1%) had ideal L1PAs postoperatively and 235 patients (39.4%) did not. Those with favorable T1PAs demonstrated significantly higher PJK rates than unfavorable T1PAs (52.0% v. 48.0%, p = 0.035). When adjusting for confounders, favorable T1PAs decreased risk of PJK development (OR: 0.532, 95% CI: 0.288-0.985, p = 0.045). After adjusting for confounders, ideal L1PAs increased risk of developing PJK at 6W, 1Y, and 2Y (OR: 1.507, 95% CI: 1.030-2.205, p = 0.035; OR: 1.670, 95% CI: 1.144-2.437, p = 0.008; OR: 1.548, 95% CI: 1.076-2.228, p = 0.018, respectively). Conclusion: T1PA/L1PA offer valuable perspectives on global alignment but fall short in acknowledging and adjusting for the great variation in ASD patients. As such, we recommend integrating the T1PA/L1PA with alternative alignment strategies to better inform clinical care.

ID: 452

A029: Global alignment following adult spinal deformity surgery is vital to long-term improvement of PROs regardless of regional alignment

Sarthak Mohanty ¹ , Christopher Mikhail ² , Fthimnir Hassan ³ , Erik Lewerenz ³ , Christopher Lai ¹ , Stephen Stephan ⁴ , Andrew Platt ⁵ , Nathan Lee ⁶ , Joseph Lombardi ³ , Zeeshan Sardar ³ , Ronald A. Lehman ³ , Lawrence Lenke ³

¹ Massachusetts General Hospital, Boston, United States,

² Cedar Sinai Medical Center, Los Angeles, United States,

³ Columbia University Irving Medical Center, New York, United States,

⁴ Scripps Health, La Jolla, United States,

⁵ Loma Linda University Health, Loma Linda, United States,

⁶ Midwest Orthopaedics at RUSH, Chicago, United States

Introduction: Significant attention has been paid to the effect of sagittal parameters on PROs. PI-LL < 10 has been considered to be optimal alignment of the lumbar spine and a reliable regional conduit for global alignment. However, the position of the head relative to the hips remains a vital element in long term satisfactory outcomes. We hypothesize that regardless of PI-LL, patients who achieve CrSVA-H < 2cm at final follow up (FU) have both greater increase and overall PROs at final FU. Methods: This was a retrospective analysis within a prospectively collected single center database of adult spinal deformity (ASD) patients who underwent corrective surgery with minimum 2yr FU. Patient demographics, perioperative data, radiographic parameters and PROs were collected at baseline (BL) and FU. Patients were placed into 3 separate cohorts based on whether they were completely aligned (CA = CrSVA-H < 2, PI-LL < 10), globally aligned (GA = CrSVA-H < 2c m, PI-LL ≥ 10), completely malaligned (MA = CrSVA-H ≥ 2 cm, PI-LL ≥ 10) at final FU. Results: 151 patients were included [CA (n = 71), GA (n = 58), MA (n = 22)]. At BL, CA was younger (mean [SEM]) (44.1 [2.2] vs. 57.6 [1.8] vs 54.7 [3.1], p = 0.0003) and had less PI-LL mismatch (1.6 [2.3] vs 27.9 [2.4] vs 25.0 [4.8], p < 0.0001) than GA and MA. CrSVA-H differed significantly between CA and MA (-1.5 [0.5] vs 4.1 [1.2], p = 0.0012) but did not between CA and GA (-1.5 [0.5] vs -1.0 [0.8], p = 0.9957). There was no significant difference in BMI or TIL across all 3 cohorts (p > 0.05). CA and GA had greater BL PROs when compared to MA, specifically in SRS22r total (p = 0.0025, p = 0.0244), self-image (p = 00032, p = 0.0074), and satisfaction (p = 0.0313, p = 0.0011). BL ODI scores differed only between CA and MA (32.2 [2.5] vs 41.1 [2.4], p = 0.0312). No differences between CA and GA were observed (p > 0.05). This relationship persisted by final FU with CA and GA possessing higher PROs, including the aforementioned PROs and ODI scores (p = 0.0016, p = 0.0044) when compared to MA. Mixed effects model of PROs stratified by the cohorts and their respective time points demonstrated CA and GA experienced greater increase in PROs when compared to MA (p < 0.05). Conclusions: ASD patients with CrSVA-H < 2cm by final FU improved significantly across the majority of PROs regardless of regional alignment when compared to pts who were both globally and regionally malaligned. Our results further emphasize that the position of the head relative to the hips is a vital element in the long-term improvement of PROs following ASD surgery.

ID: 967

A030: Staged versus same-day anterior and posterior spinal fusions: a comparative study

David Le ¹ , Spencer Smith ¹ , W.H. Andrew Ryu ¹ , Jung Yoo ¹

¹ Oregon Health Science University, Portland, United States

Introduction: Over the past several years, there has been an increase in the amount of staged anterior and posterior spinal fusions due to the increase in complexity and perioperative morbidity from performing such procedures. The difference in the length of stay and morbidity between staged and same-day spinal fusions are not yet completely understood. A paucity of literature exists on this topic; however, our study is one of the largest and most recent to date. Our objectives are to compare the length of stay and complications between 1-stage and 2-stage anterior and posterior spinal fusions across multiple centers across the United States. Material and Methods: Data collected from EPIC Cosmos from 2014 to 2023 was performed. This database consists of pooled data from hospitals across the United States. Patients included in the review underwent non-cervical anterior and posterior spinal fusions and were screened with current procedure terminology (CPT) codes that indicate they had an anterior and posterior fusion. Pooled subjects were then divided into anterior and posterior fusions performed on the same day and those who underwent staged procedures at a later date. Patients were also grouped into the number of levels that were fused (≤ 6 levels, 7-12 levels, ≥ 13 levels). Average length of stay, frequency of surgery-related complication, 30-day, and 90-day readmission rates, and rates of home discharge were collected. Multivariate regression, student t-test, and chi square test models were performed to determine if there was a difference in the variables between same day versus staged procedures. Results: A total of 2,203 patients were identified to have undergone an anterior and posterior spinal fusion from 2014 to 2023. Of those, 56% (1252) underwent same day procedures and 43% (951) underwent staged procedures. There was no difference in 30 or 90 day complications between the same day and the staged spinal fusions. Staged surgeries had a higher 30 and 90 day readmission rate for the patients who underwent fusion of ≤ 6 levels (p = 0.004, 0.001, respectively) and greater 90 day readmission rate for those who underwent staged fusions of ≥ 13 levels (p = 0.04). Length of stay was longer for those who underwent staged fusion of ≤ 6 levels compared to same day (p = 0.001); however, there were no significant difference in LOS for additional levels fused. In addition, there were no difference in the rate of discharge to home between staged and same day across all categories of fusion levels. Conclusion: Undergoing staged anterior and posterior fusions offer no benefit in terms of decreased complications or home discharge. There are higher readmissions rates for those who undergo staged fusions of ≤ 6 levels and those who undergo staged fusion of ≥ 13 levels. There are no benefits of decreased LOS for single day surgery unless patients had ≤ 6 levels fused.

301

A031: Incidence of apex fusion after surgical management of early onset scoliosis with active apex correction technique

Alaa Azmi Ahmad ¹ , Majed Dwaik ¹ , Nam Vo ² , Abdullah Shah ³ , Walid Yassir ⁴ , Mohammad Armouti ⁵ , Farah Shahin ¹ , Mohammad Awad ¹ , Haya Warasna ¹ , Mohamad Banat ¹ , Bashar Awad ¹ , Ahmad Hammad ⁶ , Yehia Bromboly ⁷

¹ Palestine Polytechnic University, Hebron, Palestine,

² Hospital for Traumatology and Orthopedic, Ho Chi Minh, Viet Nam,

³ Ghurki trust Teaching Hospital, Lahore, Pakistan,

⁴ Children hospital of Michigan, School of Medicine, Waynesstate University, Detroit, United States,

⁵ Abdali Hospital, Amman, Jordan,

⁶ American University of Beirut Medical Center, Beirut, Lebanon,

⁷ Medical School Zagazig University, Cairo, Egypt

Introduction: Active Apex Correction (APC) is a hybrid posterior tethering strategy featuring replacing a traditional SHILLA with apex non-fusion and growth modulation. The aim is to determine the rate of Apex facet fusion in children with Early Onset Scoliosis treated surgically with APC technique. Material and Methods: Seventeen patients were treated with the APC technique as index surgery for Early Onset Scoliosis with more than one year of follow-up. A 3D CT scan was done to determine the facet fusion rate in the deformity's apex controlled with posterior tethering. Results: The average follow-up time was 26.4 months (12-56), Average age at index surgery was 81.2 months (30-132), and average number of surgeries done 1.3. Apical vertebrae studied for facet fusion were the 3 vertebrae in the apex in each patient that were subjected to posterior tethering according to the APC technique. In total they were 86 apical vertebrae (172 Facets studied with 86 convex side, 86 concave side). Our observations showed that 29 facet joints were fused (16% of the total facets studied),15 were on the convex, 14 on the concave side (no statistically significant difference). Regarding the facet joint distance in the non-fused facets was 0.99 mm on the convex side and 1.08 mm on the concave side with no statistical significance difference. Conclusion: APC for Early Onset Scoliosis achieves apical growth modulation and control utilizing posterior tethering without inducing fusion. This study demonstrated that APC is an effective non-fusion technique through the low incidence of facet fusion levels at the Apex, limiting the crankshaft phenomena seen in cases with apex control through arthrodesis.

ID: 670

A032: Selection of the lowest instrumented vertebra and odds ratio of complications for structural thoracolumbar/lumbar curves in adolescent idiopathic scoliosis using a posterior approach: a systematic review and meta analysis

Asham Khan ¹ , Esteban Quiceno Restrepo ¹ , Hendrick Francois ² , Benard Okai ² , Mohamed Soliman ¹ , 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: There is no clear guideline on where to stop instrumentations in thoracolumbar and lumbar idiopathic scoliosis. The present study aims to systematically analyze the different surgical criteria to determine the LIV in thoracolumbar and lumbar structural curves. Material and Methods: A literature review was performed via PubMed and Embase, from inception to 04/01/2024. The following search strategies containing the terms: Lenke 5, Lenke 5 and posterior surgery, Lower instrumented vertebra and Lenke 5, Lower instrumented vertebra and Lenke 3, lower instrumented vertebra and Lenke 6, lower end vertebra and scoliosis were done. Results: The search yielded a total of 1693 articles. After scanning for title and abstract and eliminating the duplicates, 22 studies were selected. The L3 pooled instrumentation rate was 70.8% (95% CI 64.3-77.3) (I2 = 98.4%) p < 0.001, the L4 pooled instrumentation rate was 22.3% (95% CI 17.5-27.1) (I2 = 96.81%) p < 0.001, The L5 pooled instrumentation rate was 2.1% (95% CI 0.9-3.3) (I2 = 80.53) p < 0.001, just 5 patients had L2 as the LIV. The pooled rate of complications for L3 = LIV was 11.1% (95%CI 7.4-14.8) (I2 = 88.95%) p < 0.001, the pooled rate of complications for L4 = LIV was 7.4% (95%CI3.6-11.3) (I2 = 22.87%) p = 0.226 and, the pooled rate of complications for L5 = LIV was 43.8% (95% CI 17.8-69.7) (I2 = 77.69%) p = 0.004. When the L3 and L4 LIV complications were compared across 8 studies no significant difference was found between groups (p = 0.26). Four studies compared the complications between the L4 LIV and L5 LIV groups, favoring the L4 group OR: 0.17 (95% CI 0.08-0.36) p < 0.00001. Six studies compared the complication rates between the LIV = LEV-1 and LIV = LEV, the LEV group had significantly less associated alignment complications than the LEV-1 group OR:8.43 (95%CI 3.62-19.66) p < 0.00001. Four studies compared the complications between the LIV = LEV and LIV = LEV+1, favoring again the LEV group OR:0.23 (95%CI0.08-0.63) p = 0.004. Conclusion: The ideal fixation for thoracolumbar/lumbar curves (Lenke 3/5/6) can be L3 or L4. Fixation to L5 should be avoided due to the increased risk of coronal imbalance and severe decompensation.

ID: 2687

A033: Understanding blateral MEP changes during cord level spinal deformity surgery: etiology, significance and response

Brian Neuman ¹ , Michael Kelly ² , Zeeshan Sardar ³ , Ganesh Swamy ⁴ , Justin Smith ⁵ , Lawrence Lenke ³ , Munish Gupta ¹ , Saumyajit Basu ⁶ , Eric Klinerberg ⁷ , Robert Ravinsky ⁸ , Christopher J. Nielsen ⁹ , Stephen Lewis ⁹

¹ Washington University, St Louis, United States,

² Rady Children's Hospital, San Diego, United States,

³ Columbia University, New York, United States,

⁴ University of Calgary, Calgary, Canada,

⁵ Unversity of Virginia, Charlottesville, United States,

⁶ Kothari Hospital, Kokata, India,

⁷ UT Health Houston, Texas, United States,

⁸ MUSC, Chalreston, United States,

⁹ University of Toronto, Toronto, Canada

Introduction: Cord-level spinal deformity surgery carries a risk of neurologic injury. Intraoperative neurophysiologic monitoring (IONM) can help reduce the risk of neurologic deterioration and detect intraoperative injuries. This study aims to enhance our understanding of bilateral MEP alerts that occur during cord-level spine deformity surgery. Material and Methods: 20 international centers prospectively documented IONM (EMG, SSEP, MEP), demographics, radiographs, and surgical events of patients (10-80 years) undergoing spinal deformity correction for a major Cobb > 80° or involving a cord-level osteotomy. This study is a descriptive analysis of patients who experienced bilateral MEP alerts during these surgeries. Alerts were further classified into MEP-only or MEP associated with SSEP changes (MEP+SSEP). MEP alerts were defined as a loss of ≥ 50% of MEP amplitude from baseline. Surgical (exposure, implant placement, osteotomy, correction/rod placement, traction) and nonsurgical (systemic, anesthesia, technical) events preceding the alert were recorded. The relationship between bilateral MEP alerts with traumatic preceding events, defined as osteotomies or implant placement, was assessed. Results: Out of 349 cord-level spinal deformity surgeries, 25 patients (7%) experienced a total of 34 bilateral MEP alerts. Of the 34 MEP alerts, 19 (56%) were associated with only surgical events, 9 (26%) with only nonsurgical events, and 6 (18%) with a combination of both. 85% (29/34) of the bilateral MEP alerts were MEP-only. These alerts occurred on an average of 271 minutes from skin incision. 76% (22/29) of the time a surgical event preceded the bilateral MEP-only alert. Correction/rod insertion was the most common surgical event preceding the alert (73%, 16/22), followed by traumatic event (5/22) and other (3/22). 15% (5/34) of the bilateral MEP alerts were associated with SSEP changes (MEP+SSEP). A surgical event preceded the MEP+SSEP alert 60% (3/5) of the time. All (3/3) of the MEP+SSEP alerts with surgical preceding event occurred after a traumatic event. 80% (20/25) of bilateral MEP alerts with surgical preceding event had bilateral recovery at the time of closure. Recovery rates varied based on the type of preceding event. 88% (7/8) of alerts that occurred after a traumatic event demonstrated bilateral recovery. In contrast, the bilateral recovery rate of alerts after nontraumatic events was lower, at 76% (13/17). Among patients with a bilateral MEP alert, 20% (5/25) developed a neurological deficit immediately after surgery. This comprised 15% (3/20) from the bilateral MEP-only group and 40% (2/5) from the bilateral MEP+SSEP group. Maneuvers were performed in response to the alerts. By the time of discharge, only 8% (2/25) had a neurological deficit in the MEP-only group and 0 in the MEP+SSEP group. Conclusion: Bilateral MEP changes during cord-level spinal deformity surgery occur infrequently and are most often related to surgical events. When MEP alerts occur in isolation, they are more commonly associated with correction maneuvers and rod insertion, potentially indicating an ischemic event to the spinal cord. In contrast, MEP changes accompanied by SSEP alterations after a surgical event are typically linked to more traumatic events. Alerts after traumatic surgical events have higher rates of bilateral intraoperative recovery than alerts after non-traumatic surgical events following appropriate surgical maneuvers.

ID: 404

A034: Role of somatosensory evoked potential (SSEP) in enhancing intraoperative neuromonitoring for spinal deformity surgery - Results from a prospective multicenter study

So Kato ^1,2 , Lawrence Lenke ^2,3 , Kristen Jones ^2,4 , Sigurd Berven ^2,5 , Christopher J. Nielsen ^2,6 , Saumyajit Basu ^2,7 , Michael Kelly ^2,8 , Justin Smith ^2,9 , Samuel Strantzas ¹⁰ , Yong Qiu ^2,11 , Ferran Pellise ^2,12 , Ahmet Alanay ^2,13 , Nasir Quraishi ^2,14 , Randolph Gray ^2,15 , Go Yoshida ^2,16 , Amer Aziz ^2,17 , Stephen Lewis ^2,6

¹ The University of Tokyo, Tokyo, Japan,

² AO Spine Knowledge Forum Deformity, Davos, Switzerland,

³ Columbia University, New York, United States,

⁴ University of Minnesota, Minneapolis, United States,

⁵ University of California San Francisco, San Francisco, United States,

⁶ University of Toronto, Toronto, Canada,

⁷ Kothari Medical Center, Kolkata, India,

⁸ Rady Children’s Hospital, San Diego, United States,

⁹ University of Virginia, Charlottesville, United States,

¹⁰ Hospital for Sick Children, Toronto, Canada,

¹¹ Drum Tower Hospital of Nanjing University Medical School, Nanjing, China,

¹² Hospital Universitari de la Vall d’Hebron, Barcelona, Spain,

¹³ Acibadem Mehmet Ali Aydinlar University School of Medicine, Istanbul, Türkyie,

¹⁴ Queen's Medical Centre Campus, Nottingham, United Kingdom,

¹⁵ The Children`s Hospital Westmead, St. Leonards, Australia,

¹⁶ Hamamatsu University School of Medicine, Hamamatsu, Japan,

¹⁷ Ghurki Trust Teaching Hospital, Lahore, Pakistan

Introduction: The use of multimodal intraoperative neuromonitoring (IONM) has been advocated for ensuring safety in spinal deformity surgery. Somatosensory evoked potential (SSEP) monitors the functional integrity of the dorsal column pathways. The significance of incorporating SSEP alongside motor evoked potential (MEP) and/or electromyography (EMG) in preventing neurological deficits remains unclear. The objective of the present study was to understand the sensitivity and specificity of SSEP in predicting neurological deficits following spinal deformity surgery, and to investigate the complementary performance of SSEP to MEP/EMG. Material and Methods: Twenty international centers prospectively documented IONM, demographic details, radiographic findings, and surgical events for complex spinal deformity surgery. Patients aged 10-80 yrs, with a coronal or sagittal major Cobb > 80°, or undergoing posterior column or 3-column osteotomy, were included. A total of 526 cases were analyzed, excluding the cases with multiple alerts during a single operation. SSEPs were predominantly recorded after stimulation of posterior tibial nerves (98.9%) and peroneal nerve was occasionally used (7.2%). An IONM alert was defined as a > 50% loss of amplitude in SSEP or MEP from baseline or sustained EMG activity > 10 secs. Neurological examinations were performed pre- and post-operatively, with the occurrence of new neurological deficits being meticulously recorded. Results: SSEP alerts were identified in 16 out of 526 (3.0%), either alone (n = 4), or in combination with MEP/EMG (n = 12). Post-operative new sensory deficits were recorded in 13 (2.5%), of which 11 cases did not have intraoperative SSEP alerts (false negatives). Overall, the sensitivity of SSEP was 15.4%, and specificity was 97.3%. All false negative cases either did not have motor deficits or had deficits confined to only one or two muscle groups, implicating the root injuries. No neurological deficits were documented after 4 isolated SSEP alerts without MEP/EMG alerts and the addition of SSEP to MEP/EMG did not result in an enhancement of the sensitivity in predicting post-operative neurological deficits. Conclusion: Although multimodal IONM has been deemed beneficial for predicting post-operative neurological deficits by comprehensively assessing spinal cord function, it was revealed that the current protocol with single nerve coverage of SSEP did not contribute to improved safety in complex spinal deformity surgery. Further studies are warranted to establish the optimal protocol for IONM.

ID: 294

A035: Where does most of the coronal and sagittal correction of main thoracic and thoracolumbar curves come from in adult idiopathic scoliosis (AdIS) surgery?

Nathan Lee ¹ , Fthimnir Hassan ² , Thomas Zervos ² , Ted Shi ² , Erik Lewerenz ² , Chun Wai Hung ³ , Steven Roth ⁴ , Justin Scheer ⁵ , Lawrence Lenke ²

¹ Midwest Orthopaedics at RUSH, Chicago, United States,

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

³ Houston Methodist, Houston, United States,

⁴ University of Florida Medical Center, Gainesville, United States,

⁵ Cedar Sinai Medical Center, Los Angeles, United States

Introduction: The relative effect of intraoperative positioning with posterior column osteotomies (PCOs) and rod application on deformity correction is not clearly defined among Adult Idiopathic Scoliosis (AdIS) patients. This is the first study to quantify the impact of PCOs with positioning and rod placement on thoracic and thoracolumbar/lumbar correction in AdIS. The relative effect of intraoperative positioning with posterior column osteotomies (PCOs) and rod application on deformity correction is not clearly defined among Adult Idiopathic Scoliosis (AdIS) patients. This is the first study to quantify the impact of PCOs with positioning and rod placement on thoracic and thoracolumbar/lumbar correction in AdIS. Methods: This is a retrospective, single surgeon case series of 50 AdIS patients that underwent posterior spinal instrumented fusion (PSIF) from 2022-2023. Both structural main thoracic (MT) and thoracolumbar/lumbar curves (TL/L) were assessed at preoperative, intraoperative, and postoperative in both the coronal/sagittal planes. Measurements included Cobb angles, thoracic kyphosis (TK), lumbar lordosis (LL), and pelvic incidence (PI). A “3D TK” was used to determine the true TK, based on the axial rotation of Cobb angles (Newton et al, 2015). Paired T-tests were used. Results: For main thoracic curves, the Cobb angle decreased from 63^o ± 17 preop upright, to 51^o ± 17 preop supine, to 32^o ± 13 after positioning/PCOs, to 16^o ± 11 after rod correction and 13^o ± 9 postop upright (p < 0.001). Thus, 66% improvement in the main thoracic curve occurred by positioning/PCOs alone while 34% occurred by rod correction. 3D TK increased from 15^o ± 17 preop upright and 12^o ± 14 preop supine, to 28^o ± 10 after positioning/PCOs (p < 0.001), to 31^o ± 8 after rod correction (p = 0.08), to 34^o ± 6 postop upright (p = 0.04). Thus, 80% of increased kyphosis was due to positioning/PCOs while 20% from rod correction. For thoracolumbar/lumbar curves, Cobb angle decreased from 61^o ± 14 preop upright, to 48^o ± 10 preop supine, to 34^o ± 11 after positioning/PCOs, to 13^o ± 7 after rod correction and 11^o ± 6 postop upright (p < 0.001). Thus 56% improvement in thoracolumbar curves occurred by positioning/PCOs while 44% after rod correction. LL changed from 53^o ± 11 preop upright, to 60^o ± 8 intraop after positioning/PCOs (p = 0.02), to 52^o ± 8 after rods in the context of a mean PI 53^o ± 10 with preop/postop PI-LL mismatch -0.3 ± 14/-0.7 ± 8. Conclusions: For both main thoracic and thoracolumbar/lumbar curves, most of the coronal correction occurs after positioning/PCOs as opposed to rod correction (main thoracic: 66% vs 34% (thoracolumbar: 56% vs. 44%). Surprisingly, positioning/PCOs is kyphogenic and restores most of the TK (80%) vs. rod placement (20%). In contrast, positioning/PCOs increases lordosis for the lumbar spine and may be adjusted after rod placement.

ID: 1820

A036: Age impacts gait recovery timeline following surgery to correct adult spinal deformity

Isador Lieberman ¹ , Bethany Wilson ² , Kyle Robinson ² , Sara McMahan ²

¹ Texas Back Institute, Frisco, United States,

² Texas Back Institute, Plano, United States

Introduction: Recovery after adult spinal deformity (ASD) correction is multifaceted, depending on a range of factors. While surgical intervention aims to alleviate pain and improve mobility, age may play a role in the extent and rate of postoperative recovery related to mobility. By analyzing outcomes, including pain levels and walking performance, this research explores how age impacts presurgical functional deficits and recovery trajectories. The findings aim to provide a deeper understanding of how age-related factors influence surgical success and long-term functional improvement in patients undergoing ASD correction. Material and Methods: This preliminary analysis focused on a prospective, non-randomized study of a concurrent cohort of ASD patients undergoing surgery, alongside asymptomatic controls. ASD subjects were divided into three cohorts based on age and compared with asymptomatic controls; 1) Ages 19-49, 2) Ages 50-69, and 3) Ages 70+. Evaluations were conducted preoperatively (P0), 3 months post-surgery (P3), and 1-year post-surgery (P12). Participants were assessed with Visual Analog Scales for Pain and the Oswestry Disability Index, and functional performance through over-ground walking tests. Kinematic motion and kinetic ground reaction force data were captured using 3D motion tracking and force plates. Results: This study included 24 ASD subjects ages 19-49 (9 M/15 F, Age: 30.8 ± 10.9, BMI: 25.6 ± 5.0), 83 ASD subjects ages 50-69 (24 M/59 F, Age: 62.7 ± 6.0, BMI: 28.7 ± 6.4), 53 ASD subjects ages 70+ (15 M/38 F, Age: 74.1 ± 2.9, BMI 27.9 ± 4.7), and 35 asymptomatic controls (15 M/20 F, Age: 39.0 ± 13.3, BMI: 24.7 ± 3.6). Preoperatively, the 19-49 yo group exhibited significantly lower pain and disability scores than the 50-69yo and 70+ groups, whose scores were comparable. However, the data demonstrates significant improvement in pain and disability for each group at P3 compared to P0, then stabilized with no significance between groups at either P3 or P12. Preoperatively, the 50-69 yo and 70+ groups demonstrated significant spatiotemporal differences - including reduced walking speed, stride length, and gait deviation index (GDI) - compared to the 19-49 yo group and controls. At P3, walking speed and stride length for 50-69 and 70+ groups were significantly lower than in 19-49 yo subjects. No significant differences in spatiotemporal measures were found between the 19-49yo and 50-69yo groups at P12, though the 19-49 yo and 70+ groups still differed in walking speed and stride length. GDI improved in the 50-69 and 70+ age groups at P3, removing the significant difference between these groups and 19-49 yo subjects. No significant differences in gait quality were observed between the 50-69 yo and 70+ groups, or between the 19-49 yo group and asymptomatic controls, at any follow-up. Significance was set at p < 0.05. Conclusion: The findings suggest that, while all age groups experienced significant improvements in pain and disability post-surgery, age-related differences in mobility persisted. The 19-49yo group showed earlier improvements in spatiotemporal gait parameters compared to older age groups, particularly those over 70, who continued to exhibit slower walking speeds and shorter stride lengths at P12. However, improvements in GDI across age groups highlight that gait quality can still recover over time, emphasizing the need to consider age-specific factors in postoperative recovery planning for ASD patients.

OP05: Basic Science 1

ID: 993

A037: Development of a smart implant for monitoring spinal stabilization using a rod-integrated measurement system - a cadaver biomechanic study

Luis Rodríguez Pino ¹ , Philip Johannes Steinbild ² , Nils Frederik Wieja ² , Stefan Zwingenberger ¹ , Anja Winkler ² , Robert Gottwald ² , Niels Modler ² , Werner Schmoelz ³ , Disch Alexander C. ¹

¹ University Center of Orthopaedics, Traumatology & Plastic Surgery and University Comprehensive Spine Center (UCSC), University Hospital Carl Gustav Carus Dresden, TU Dresden, Dresden, Germany,

² Institute of Lightweight Engineering and Polymer Technology, TU Dresden, dresden, Germany,

³ Department of Orthopaedics and Traumatology, Medical University of Innsbruck, Austria, Innsbruck, Austria

Introduction: The standard technique to treat thoracolumbar spinal instabilities is a posterior stabilization using pedicle screw rod systems. Spinal consolidation is often controlled using radiographs or CT-scans, but their value regarding misinterpretation is continuously under discussion. A measurement device coupled to spinal implants, that can directly monitor spinal loads, might improve follow-up of different spinal stabilization indications. Material and Methods: Four strain gauges were applied to conventional carbon fiber reinforced polymer (CFRP) rods for posterior stabilization, forming integrated sensor rods. In combination with pedicle screws, a series of 8 cadaver spine test models were instrumented with the sensor rods, creating a bisegmental thoracolumbar stabilization (Th11-L1). A customized measurement system using an integrated Bluetooth chip transmitted the acquired multidirectional strain data to a computer. To be able to simulate a healing process, a standardized fenestration defect was induced at the middle vertebra at T12. To simulate the healing process, four silicone mats of different shore hardness (0 ShA, 8 ShA, 30 ShA, 45 ShA) were inserted into the defect with 0 ShA simulating a fractured vertebra. The whole setup was monitored through both the implant measurement and an optical 3D system. Flexibility tests with pure moments of 5 Nm were applied to the specimens using a custom-made spine tester. Results: The newly introduced sensor rod system demonstrated reproducible strain data. Even with gross differences in flexibility and bone density between the specimens, significant difference between the maximum strains with each silicone was measured. With increasing hardness of the silicone, the measured strains acting on the rods decreased. A significant increase in strain was observed between the intact state and the sequence after fenestration was performed, instrumented with the least stiff silicone (0 ShA). During the following simulation of the healing process, from 0 ShA to 45 ShA, a significant decrease in strain was observed. Conclusion: The introduced rod sensor system demonstrated reliable strain measurement for different stable and unstable conditions in a standardized thoracolumbar spine test model. Increasing stability equally reduced strain on the implant. A development of the first prototype with a further miniaturization of the system and integration in the rod is planned, to enable future animal model implantation, generating in vivo data and paving the path for a trial in patients.

ID: 2010

A038: Is Cutibacterium acnes implicated in cervical degenerative disc disease? A prospective study of disc cultures

Logan Lake ¹ , Esha Reddy ² , Isaac Hale ¹ , Paul McMillan 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: The potential relationship between “indolent” intervertebral disc infection and disc degeneration has been of great interest in recent years. There has been widespread investigation within the context of lumbar disease, but little research has focused on the cervical spine. This study aims to characterize the prevalence of C. acnes in patients with cervical degenerative disc disease (DDD) and identify risk factors for infection. Material and Methods: This prospective study includes patients presenting to a single, academic orthopaedic spine surgeon for management of cervical DDD between May 2021 and June 2024. Both patients with a history of prior spine surgery (HSS) and primary surgical candidates (PSCs) were enrolled. Following rigorous preoperative antisepsis procedures, the surgical site was draped, and a standard surgical approach was used for exposure, decompression, and removal of intervertebral disc material. Samples from paraspinal musculature were collected as internal controls. Disc samples were handled with fresh instruments only and were immediately transferred to a sterile container upon retrieval. Specimens were promptly delivered to the microbiology lab where aerobic and anaerobic cultures were incubated for 14 days. Quantitative-PCR was used for identification of bacterial species. Demographic details, history of presenting symptoms, medical and surgical histories, and other patient characteristics were recorded at the time of surgery. Statistical analysis included independent t-tests and Pearson Chi-square tests (Fisher’s Exact) for continuous and nominal variables, respectively. Significance was defined as p < .05. Results: Samples from 45 patients were included for analysis. 15 patients had undergone at least one prior spine surgery while 30 were being operated on for the first time. There were no significant differences in patient characteristics between these groups. Interestingly, 10 of 30 disc samples from PSCs resulted in bacterial growth, while only 1 of 15 patients with a HSS had a positive culture (p = .070). Among first-time patients, eight grew C. acnes (26.67%) and two grew Staphylococcus epidermidis (6.67%). The population of PSCs that grew c. acnes (n = 8) was compared to those who demonstrated no culture growth (n = 20). There were no statistically significant differences between these groups regarding mean age, BMI, race, smoking status, history of acne, history of epidural spine injections, recent antibiotic usage, or Modic score. Despite 15 of 28 of subjects being female, all 8 cultures positive for C. acnes originated from male patients (p < .001). Over 60% of males undergoing surgical decompression for DDD had cultures indicative of an indolent spine infection. Conclusion: To the best of our knowledge, this study represents the largest cohort of patients with cervical DDD from which cultures have been analyzed for indolent infection. Despite predominance among normal skin flora, microenvironments with a high C. acnes biomass predispose underlying tissue to developing chronic bacterial infections. Our data reveal a strong association between male sex and growth of c. acnes from cervical intervertebral disc cultures. This may be linked to hormone-driven, sex-based variation in the density and distribution of sebaceous glands across regions of the skin. Further investigation of this relationship is essential to developing an effective approach for managing these patients.

ID: 2304

A039: Mechanism study of neuroinflammation induced by distraction stress via S1PR2 nuclear translocation in distraction spinal cord injury with spinal deformity

Bo Han ^1,2 , Weishi Liang ^1,3 , Xianjun Qu ¹ , Yong Hai ^1,3

¹ Joint Laboratory for Research & Treatment of Spinal Cord Injury in Spinal Deformity, Laboratory for Clinical Medicine, Capital Medical University, Beijing, China,

² Beijing Jishuitan Hospital, Capital Medical University, Beijing, China,

³ Beijing Chaoyang Hospital, Capital Medical University, Orthopedic Surgery, Beijing, China

Introduction: Distraction spinal cord injury (DSCI) is a serious complication of spinal deformity correction surgery, caused by excessive distraction and compression. The sphingosine 1-phosphate (S1P) pathway, especially S1PR2, plays a role in neuroinflammation, but its involvement under mechanical stress is not well understood. This study aims to explore the role of S1PR2 in neuroinflammatory injury after DSCI, focusing on its nuclear translocation and DNA methylation in microglia. Material and Methods: A large animal model of distraction spinal cord injury (DSCI) that mirrors clinical conditions was created, validated by a 75-100% reduction in motor evoked potentials. Immunofluorescence was used to analyze microglial activation. RNA-Seq and bioinformatics identified DSCI mechanisms and targets, confirmed by Western blotting. Our custom SD rat DSCI model was assessed for stability and treated with the S1PR2 inhibitor JTE-013. In vitro, we used BV2 microglia to study S1PR2/ERK/STAT3 and S1PR2/DNMT1/SOCS1 pathways in neuroinflammation. S1PR2 nuclear translocation and S1PR2-DNMT1 complex formation were examined by immunoprecipitation, and cytokine levels in spinal cord, cerebrospinal fluid, and serum were measured using ELISA and flow analysis. Results: Compared to the Sham group, the DSCI group showed significantly reduced behavioral scores. LFB staining revealed severe demyelination, while HE and Nissl staining indicated a significant loss of neurons and increased inflammation, congestion, and edema. Fluorescence staining showed a significant rise in CD16 and CD206 in microglia/macrophages (p < 0.05), and elevated levels of IL-1β, IL-6, and TNF-α in the spinal cord and cerebrospinal fluid (p < 0.05). KEGG analysis indicated that S1PR2 was significantly upregulated at 7 days post-DSCI, while other S1PR family members remained unchanged. Our custom-designed DSCI rat model demonstrated stability and efficiency. Treatment with the S1PR2 inhibitor JTE-013 improved BBB and ramp test scores, reduced hindlimb muscle atrophy, and alleviated spinal cord edema and hemorrhage. JTE-013 also reduced white matter demyelination and improved neuron survival. S1PR2 expression increased after DSCI, with SPHK2 levels rising in tandem. Immunofluorescence revealed S1PR2 in the nucleus and elevated expression in both the membrane and nucleus. The NF-κB inflammatory pathway and levels of TNF-α and IL-6 also increased with distraction duration. Western blot and Co-IP analyses showed enhanced interactions between DNMT1 and S1PR2, and between S1PR2 and KPNB1 proteins under stress. Under 10% distraction stress, DNMT1 expression in BV2 nuclei increased after 6 hours, with decreases in SOCS1 and increases in STAT3 (p < 0.01). S1PR2 knockdown reduced total and membrane S1PR2 levels, impairing receptor activation and signaling. After 14 days of DSCI, serum levels of TNF-α, CCL3, IL-1β, and CXCL1 increased but were reduced by JTE-013. Conclusion: In this study, DSCI models in Bama pigs and SD rats were established. Microglial activation, including M1/M2 and macrophages, is key in secondary neuroinflammation. S1PR2 levels rise with stress duration and damage, and it translocate to the nucleus via KPNB1, binding DNMT1 to regulate SOCS1 methylation. This activates the SOCS1/STAT3 pathway, causing neuroinflammation. JTE-013 reduces inflammation by inhibiting S1PR2 activation and nuclear translocation. These findings provide insights into DSCI inflammation mechanisms and potential drug targets.

ID: 2603

A040: Placental mesenchymal stem cells and extracellular vesicles on a dural graft improved motor function recovery after acute spine cord injury

Jose Castillo ¹ , Christopher Privetti ² , Allan Martin ¹ , Richard Price ¹ , Kee Kim ¹ , Aijun Wang ²

¹ UC Davis Medical Center, Sacramento, United States,

² UC Davis, Sacramento, United States

Introduction: Spinal cord injury (SCI) is a devasting disease associated with severe disability and no effective cure. We have shown placental mesenchymal stem cells (PMSCs) applied in utero improve ambulatory function and preserve motor neurons in an ovine model of spina bifida and have begun a first-in-human clinical trial for fetal spina bifida. PMSCs work through paracrine mechanisms and extracellular vesicles (EVs) have been shown to have neuroprotective properties. We hypothesized that PMSCs and PMSC EVs would provide a similar neuroprotective effect in SCI. Methods: Female Sprague Dawley rats were given a right C5 hemi-contusion injury using an RWD Precise Impactor. Immediately after the injury, the dura was opened at the injury site and rats were treated with one of the following repair treatments: extracellular matrix (ECM) only patch (n = 10), 1^st trimester PMSCs seeded on ECM at a seeding density of 300,000 cells/cm2 (n = 13), 1x10^9 1^st trimester PMSC EVs seeded on ECM (n = 9), 5x10^5 2^nd trimester PMSCs seeded on ECM (n = 10), and 1x10^9 2^nd trimester PMSC EVs seeded on ECM (n = 8). 8 rats served as sham controls and received a C5 laminectomy, but they did not receive a SCI. Weekly motor function testing included Irvine, Beatties, and Bresnahan (IBB) Forelimb Recovery Scale testing by blinded reviewers. After 8 weeks, rats were euthanized, and tissue collected for histology. Results: Four 2^nd trimester PMSC lines were evaluated with our established anti-apoptotic neuroprotection assay and a single cell line was chosen based on increased neurite outgrowth. IBB scoring showed 1^st trimester PMSC-ECM (p = 0.017) and 1^st trimester PMSC-EV-ECM (p = 0.015) rats had significantly improved motor function of the ipsilateral forelimb compared to rats that were treated with ECM only. Additionally, 2^nd trimester PMSC-ECM treatment group had a significant increase in motor function (p = 0.014) compared to the group treated with ECM only. However, rats treated with 2^nd trimester PMSC-EV-ECM did not show a significant improvement in motor function compared to rats treated with ECM only (p = 0.1275). Immunohistochemistry showed significantly increased axons in rats treated with 1^st trimester PMSC-ECM (p = 0.006) and 1^st trimester PMSC-EV-ECM (p = 0.00004) compared to ECM only. Increased activated microglia and fewer reactive astrocytes were also seen in 1^st trimester PMSC and EV treated groups. Conclusion: PMSCs and PMSC-EVs improved motor function recovery in a rodent model of SCI. 1^st trimester PMSCs and EVs performed better than 2^nd trimester PMSCs and EVs. Reduced gliosis and increased axon counts suggest neuroprotective capabilities of PMSC treatment.

ID: 2247

A041: Phillygenin inhibits neuroinflammation and promotes functional recovery after spinal cord injury via TLR4 inhibition of the NF-κβ signaling pathway

Yu Zhang ¹

¹ The First Affiliated Hospital of Nanchang University, Department of Orthopedics, Nanchang, China

Introduction: Spinal cord injuries (SCIs) trigger a cascade of detrimental processes, encompassing neuroinflammation and oxidative stress (OS), ultimately leading to neuronal damage. Phillygenin (PHI), isolated from forsythia, exhibits multiple biomedical uses, including anti-neuroinflammation activity. This study delves into the role and mechanisms of PHI in the activation of microglia-mediated neuroinflammation and subsequent neuronal apoptosis following spinal cord injury. Material and Methods: A rat SCI model was employed to investigate the impact of PHI on inflammation, axonal regeneration, neuronal apoptosis, and the restoration of motor function. In vitro, neuroinflammation models were induced by stimulating microglia with lipopolysaccharide (LPS), and the influence of PHI on pro-inflammatory mediator release in LPS-treated microglia and its underlying mechanisms were detected. Furthermore, we established a co-culture system involving microglia and VSC 4.1 cells to assess PHI's role in activating microglia-mediated neuronal apoptosis. Results: In vivo, PHI significantly inhibited the inflammatory response and neuronal apoptosis while enhancing axonal regeneration and improving motor function recovery. In vitro, PHI exhibited a dose-dependent inhibition of inflammation-related factors released by polarized BV2 cells. The Swiss Target Prediction online database predicted toll-like receptor 4 (TLR4) as a target protein for PHI. The Molecular Operating Environment software conducted a molecular docking of PHI within the TLR4 protein, resulting in a binding energy interaction of -6.7 kcal/mol. PHI inhibited microglia-mediated neuroinflammation, reactive oxygen species (ROS) production and activity of the NF-κb signaling pathway. PHI also increased mitochondrial membrane potential (MMP) in VSC 4.1 neuronal cells. In BV2 cells, PHI attenuated the overexpression of TLR4-induced microglial polarization and significantly suppressed the release of inflammatory cytokines. Conclusion: PHI ameliorates spinal cord injury-induced neuroinflammation by modulating the TLR4/MYD88/NF-κB signaling pathway. PHI has the potential to be employed in the treatment of SCI, representing a novel candidate drug for addressing neuroinflammation mediated by microglial cells.

Keywords: Neuroinflammation, Neuronal apoptosis, NF-κB signaling pathway, Phillygenin, Spinal cord injury

ID: 25

A042: Measuring the pressure changes at spinal epidural and intracranial areas in fresh cadavers during the full endoscopic lumbar spine surgery with continuous irrigation - Preliminary report

Metehan Öztürk ¹ , Ilyas Dolas ¹ , Ali Guven Yorukoglu ^1,2 , Dogukan Ozler ¹ , Duran Sahin ¹ , Musa Samet Özata ¹ , Ceyhun Kucuk ³ , Duygu Dolen ¹ , Tugrul Cem Unal ¹ , Akın Sabancı ¹ , Aydın Aydoseli ¹ , Yavuz Aras ¹ , Altay Sencer ¹

¹ Istanbul University, Faculty of Medicine, Neurosurgery, Istanbul, Türkyie,

² Florence Nightingale Hospital, Scoliosis and Spine Center, Istanbul, Türkyie,

³ Forensic Science, T.C. Adli Tıp Kurumu , Istanbul, Türkyie

Introduction: During the full-endoscopic lumbar discectomy (FELD) procedure, continuous irrigation is employed. However, this continuous irrigation can result in pressure changes within the surgical field. These pressure alterations in the lumbar epidural space may extend to affect higher spinal levels, potentially causing a rise in intracranial pressure (ICP). Especially in the last years, some complications in patients who underwent FELD have been reported such as head-neck pain, seizures, and even retinal hemorrhage. The reason for these complications is considered as the heightened ICP during FELD procedures. Within the scope of our study, our objective is to assess changes in ICP and epidural pressures across different spinal levels induced by continuous irrigation during FELD. Material and Methods: Thus far, our study was conducted using eight fresh cadavers ages 18-75, devoid of cranial or spinal trauma and without any previous spinal surgeries. Initially, we placed a catheter intraventricularly and needles at the epidural space of C2-3, T6-7, and L3-4 levels. Subsequently, these catheters and needles are connected to digital manometers. Different stages of FELD are performed on fresh cadavers, and data is saved instantly. Results: While we are using continuous irrigation systems for the FELD technique, we mainly noticed these irrigation systems can increase pressures in other spinal epidural spaces and even the intracranial area as well as the operation area. Especially, choosing of appropriate irrigation mode and pressure level for this continuous irrigation system during the surgery is highly significant for avoiding these pressure changes. Furthermore, when the measurement results were examined we noticed different brands of endoscopes and their design differences can affect pressure changes. Another consideration is that certain maneuvers, consciously employed to enhance the visualization of the surgical area (such as blocking the irrigation or working channel of the endoscope), can lead to an increase in pressure. These maneuvers can also induce rapid pressure changes in other spinal levels and intracranial areas. Conclusion: During FELD understanding the underlying causes of these pressure fluctuations and implementing strategies to mitigate them are paramount. For instance, use of the maneuvers that can increase pressure in surgical site should be avoided, due to the potential increased risk of complications associated with these sudden pressure changes. This way, potential complications can be avoided by preventing changes in epidural pressure during surgery, making FELD a safe alternative in the treatment of lumbar disc herniation.

ID: 2192

A043: Unravelling the role of complement proteins activation in intervertebral disc degeneration

S. Rajasekaran ¹ , Karthik Ramachandran ¹ , Sharon Miracle Nayagam ² , Chitraa Tangavel ² , Sri Vijay Anand KS ¹

¹ Ganga Hospital, Department of Spine Surgery, Coimbatore, India,

² Ganga Hospital, Ganga Research Centre, Coimbatore, India

Introduction: The complement system, a network of proteins regulating immune and inflammatory responses, has been implicated in intervertebral disc degeneration (IDD) pathogenesis. Tissue-specific complement activation in degenerated discs is well-established, but systemic expression in IDD patients plasma is less understood. This study investigates the levels of complement proteins in disease plasma to understand their implications during the disease progression. To investigate the role of altered complement proteins activation in IVDD by understanding the (dis)similarities between the proteome profiles of plasma in normal healthy volunteers and patients with IVDD and thereby correlate with the tissue proteins of the IVDD. Material and Methods: The study included 11 healthy volunteers (HV) with no history of low back pain and MRI of the lumbar spine showed Pfirmann grading I. The diseased group included 39 patients with IVDD with Pfirmann grades III and IV who underwent discectomy surgery. Plasma samples were collected from both the HV (HV-plasma) and diseased groups (DD-plasma). Disc tissues obtained during surgery constituted DD-tissue. Global proteomic analysis of human plasma and tissue samples was performed using high-throughput proteomic techniques, including mass spectrometry. Results: Analysis of complement pathways revealed significant upregulation of classical pathway components namely C4BPA, C4a, C4b, C2, C3, and C3/C5 convertase, with a notable downregulation of pathway regulators like C1q, C1r, factor D, clusterin and vitronectin. The lectin pathway showed significant upregulation of MASP1. The alternate pathway exhibited upregulation of MAC constituents and regulatory proteins (CFH, CFI), suggesting their role in immune defense. Interestingly in the corresponding disease tissue, we observed downregulation of all the complement proteins discussed above except for C1q which is upregulated. Conclusion: The study reveals altered complement activation during IVDD. The correlation between complement levels inside the DD tissue and in the DD plasma has to be studied further to understand the actions of complement proteins in an IDD context.

ID: 420

A044: C-reactive protein, high-sensitivity C-reactive protein and interleukins as predictors of lumbar disc herniation surgery outcomes

Esteban Espinoza ¹

¹ Hospital San Camilo, Division of Neurosurgery, San Felipe, Chile

Introduction: Assessing clinical prognosis following lumbar disc herniation surgery is crucial for optimizing patient outcomes. Various biomarkers, including interleukins, C-reactive protein (CRP), and high-sensitivity C-reactive protein (hs-CRP), have been studied to determine their utility in predicting postoperative recovery and complications. Material and Methods: A narrative literature review was conducted to evaluate the potential of CRP, hs-CRP, and interleukins as biomarkers for predicting postoperative outcomes following lumbar disc herniation surgery. The review included observational studies, randomized controlled trials, and animal trials published in English. The target population comprised adult patients who had undergone surgery for lumbar disc herniation. The primary objective was to identify key interleukins, CRP, and hs-CRP and assess their clinical utility in predicting postoperative outcomes and informing treatment decisions. Studies that did not include measurements of interleukins, CRP, or hs-CRP were excluded. A comprehensive search was performed in the PubMed database using MeSH terms related to interleukins, C-reactive protein, high-sensitivity C-reactive protein, lumbar disc herniation, surgery, inflammation, and clinical prognosis. The search was limited to articles published from 2000 onwards. The author independently screened the titles and abstracts of the retrieved articles. The full texts of eligible studies were subsequently reviewed to ensure adherence to inclusion and exclusion criteria. Extracted data were tabulated, and a narrative synthesis was conducted. Results: The review highlighted CRP, hs-CRP, and interleukins IL-6, IL-12, and IL-17 as key biomarkers. CRP and hs-CRP: Elevated CRP levels post-surgery indicate tissue damage and inflammation, correlating with poorer recovery outcomes. Preoperative hs-CRP levels can predict postoperative recovery, with higher levels associated with worse outcomes. IL-6: Postoperative IL-6 levels correlate with pain and disability improvement, making it a useful marker for predicting recovery. Higher preoperative IL-6 levels are associated with more severe pain and longer disease duration, indicating its potential role in early diagnosis and prognosis. IL-12 and its receptors: IL-12 and its receptors (IL-23R and IL12RB2) are elevated in patients with lumbar disc herniation and decrease post-surgery, correlating with clinical improvement. These markers are negatively correlated with treatment duration and positively correlated with clinical efficacy, suggesting their potential as therapeutic targets. IL-17 and Th17 lymphocytes: Higher levels are associated with increased pain intensity and inflammation in patients with ruptured lumbar discs. These markers are positively correlated with pain scores and inflammatory mediators like prostaglandin E2 (PGE2), indicating their role in the inflammatory response and pain perception. Conclusion: CRP, hs-CRP, IL-6, IL-12, and IL-17 have been studied as biomarkers for assessing clinical prognosis after lumbar disc herniation surgery. IL-6 and CRP are particularly significant, correlating with postoperative recovery and tissue damage. The hs-CRP serves as a predictive marker for recovery outcomes, while IL-12 and IL-17 provide insights into the inflammatory response and pain intensity. These biomarkers collectively offer valuable information for predicting and monitoring patient recovery post-surgery. However, further studies are needed to fully evaluate their clinical utility.

ID: 912

A045: Inheritance of adolescent “idiopathic” scoliosis (AIS): pedigree analysis of 26 families with familial AIS

Laura Marie-Hardy ¹ , Serge Zakine ¹ , Hugo Marty ¹ , Thomas Courtin ² , Pascal-Moussellard Hugues ¹ , Alexis Brice ³

¹ University Institute for Spine Surgery, Sorbonne University, Paris, France

² Necker Hospital, Paris, France

³ Brain Institute of Paris, Paris, France

Introduction: Adolescent idiopathic scoliosis (AIS) is a three-dimensional deformity of the spine, affecting 1-3% of the population. Its etiology is still debated, but a genetic involvement is certain, alongside with epigenetic and environmental factors. Isolated or sporadic cases are frequent, but AIS also affect families, with a reported heritability up to 38%. The main goal of this study was to evaluate the prevalence and the transmission of AIS in a large cohort of familial AIS. Material and Methods: Pedigree of 26 families with at least 2 confirmed cases of AIS were studied with confirmation and characterization of scoliosis (Cobb angle, Lenke classification) in affected individuals, as well as the absence of scoliosis signs in healthy relatives. The prevalence of AIS was calculated after correction for the recruitment bias. The transmission was first analyzed globally, then according to the gender of the affected parents and children. Results: 26 families were included, consisting of 94 patients affected with AIS, adjusted to 66 patients and 160 healthy relatives in the analysis corrected by the proband method, for a prevalence of 29.2%. The transmission of AIS was higher to daughters (49%) than to sons (17%) of affected parent, suggesting a Carter effect. Moreover, out of 66 AIS patients in the proband-adjusted analysis, 49 (74.2%) were female and 17 (25.8%) male (ratio = 3), demonstrating the higher penetrance in female for familial AIS. Conclusion: This study underlines an autosomic dominant mode of inheritance in familial idiopathic scoliosis, with an incomplete penetrance. Genetic research in scoliosis should focus on those families to discover significant causative variants.

OP06: Novel Technologies and Innovations 1

ID: 2399

A046: Efficacy and safety of ultrasound-guided percutaneous endoscopic lumbar discectomy in china: a systematic review and meta-analysis

Bin Zheng ¹

¹ Peking University People's Hospital, Spine Surgery, Beijing, China

Introduction: Percutaneous endoscopic lumbar discectomy (PELD) has become the preferred minimally invasive surgical treatment for lumbar disc herniation. This study aims to conduct a systematic literature review and meta-analysis to assess the efficacy and safety of ultrasound-guided PELD compared to X-ray-guided PELD. Methods: A comprehensive literature search was conducted in PubMed, Cochrane Library, OVID, Embase, and China National Knowledge Infrastructure database up to August 2024. Studies were included if they compared ultrasound and X-ray-guided PELD in patients with lumbar disc herniation. Risk of bias and quality of evidence were assessed using Cochrane Collaboration tools and the Newcastle–Ottawa Scale. Meta-analysis was performed using RevMan 5.4. Results: Seven studies were included, with a total of 767 patients (383 ultrasound-guided PELD, 384 X-ray-guided PELD). Ultrasound guidance significantly reduced fluoroscopy shots, radiation dose, fluoroscopy time, and working channel establishment time compared to X-ray guidance. Ultrasound also demonstrated higher one-time puncture success rates. No significant differences are found in overall operative time, complications, postoperative pain scores (VAS), or long-term functional outcomes (ODI and satisfaction rates). Conclusions: Ultrasound-guided PELD reduces radiation exposure and improves the efficiency of puncture and working channel establishment without compromising surgical outcomes. However, larger, high-quality randomized controlled trials are needed to validate these findings across diverse populations.

ID: 1999

A047: Risk of refractures in the sandwich vertebrae within one year after percutaneous vertebral augmentation

SI Chen ¹

¹ Banan Hospital of Chongqing Medical University, Orthopaedics, Chongqing, China

Introduction: The prognosis of sandwich vertebrae (SDV) formed after percutaneous vertebral augmentation (PVA) has become a clinical concern. This work aimed to investigate the risk factors for refractures in sandwich vertebrae and to construct a predictive model from this. Material and Methods: This study retrospectively analyzed patients who underwent percutaneous vertebral augmentation with formation of sandwich vertebrae from January 2020 to July 2023 at Banan Hospital of Chongqing Medical University. Patients were divided into a refracture group and a control group according to the presence or absence of refracture of the sandwich vertebrae during the 1-year postoperative follow-up period. Independent predictors were confirmed using the least absolute shrinkage and selection operator (LASSO) method. Visualization of the model was made possible with a static nomogram. The discrimination, calibration, and clinical applicability of the model were assessed by Area under the receiver operating characteristic curve (AUC), calibration curve analysis, and Decision curve analysis (DCA). Finally, we internally verified the nomogram using the bootstrap method. Results: A total of 259 patients were included in this study and 36 patients had refracture of SDV within one year. Low bone density (OR = 4.501, 95% CI: 2.519-8.863, p < 0.001), the number of PVA > 3 (OR = 3.773,95% CI: 1.480-9.734, p = 0.005), not antiosteoporosis (OR = 3.435,95% CI: 1.440-8.896, p = 0.007), and kyphosis angle of sandwich fracture segments > 10° (OR = 9.504,95% CI: 3.646-26.537, p <0.001) were screened as independent risk factors. The AUC of the model constructed based on this was 0.867 (95% CI: 0.822-0.920). The calibration curves and DCA also verified that the model had satisfactory practical consistency and clinical applicability. The internally validated AUC was 0.878 (95% CI: 0.826-0.925), validating the stability of the model. Conclusion: Bone density, the number of PVA, antiosteoporotic, and kyphosis angle of sandwich fracture segments were associated with refracture within one year of SDV, and a model based on this had good predictive efficacy.

ID: 551

A048: The burden of quantitative-CT (Q-CT) proven osteoporosis in subjects scheduled for minimally invasive transforaminal lumbar interbody fusion

Sunil Chodavadiya ¹

¹ Bombay Hospital, Mumbai, India

Introduction: Undiagnosed osteoporosis in patients undergoing MIS TLIF carries risk of implant failure, low fusion rates and related complications. Q-CT is a promising tool for accurate assessment of trabecular bone mineral density (BMD) and has several proven advantages over DEXA scan. This study aims to evaluate the prevalence of Q-CT-proven osteoporosis in patients undergoing MIS-TLIF. Materials and Methods: A prospective study of pre-operative Q-CT scans of 113 consecutive patients who were scheduled to undergo MIS TLIF between OCT-2022 and December-2023 was performed. Demographics of patients were recorded. Patients were categorized into normal BMD, osteopenia, and osteoporosis. Prevalence of osteoporosis and osteopenia recorded. Results: Among the 113 patients included in the study, [62 (55%)] were diagnosed with osteoporosis, [42, (37%)] with osteopenia, and [9 (8%)] with normal BMD. Conclusion: The prevalence of osteopenia and osteoporosis is high in patients undergoing MIS TLIF. Given its true reflection of spinal trabecular bone density and the loopholes associated with DEXA scan, it is recommended that all patients scheduled for MIS TLIF undergo Q-CT preoperatively.

ID: 1482

A049: Pedicle screw placement in thoracolumbar spine: comparison of fluoroscopy and 3D navigation

Anna Wagner ¹ , Jula Gierse ¹ , Benno Bullert ¹ , Eric Mandelka ¹ , Paul Alfred Grützner ¹ , Sven Vetter ¹

¹ BG Klinik Ludwigshafen, Klinik für Unfallchirurgie und Orthopädie, Ludwigshafen, Germany

Introduction: The insertion of pedicle screws carries a risk of screw misplacement, which may lead to complications such as neurovascular damage or poor stability. Freehand pedicle screw placement under fluoroscopic control as well as navigation systems represent commonly employed methods. They vary in screw placement accuracy. Navigated pedicle screw placement can be applied to allow for more accurate trajectory planning and screw placement compared to fluoroscopic guidance. This study compares 3D navigation systems with 2D-fluoroscopy controlled placement of pedicle screws regarding accuracy in the thoracolumbar region. Material and Methods: This prospective clinical trial included 45 patients undergoing dorsal stabilization in the thoracolumbar region (T1-L5), who were randomized into two groups based on the intraoperative imaging technique used. The first group consists of 30 patients who were treated using 2D fluoroscopy, while in the second group 15 patients were treated using 3D navigation. The same C-Arm Cone Beam CT (cCBCT) was used in both groups. In postoperative CT scans the accuracy of screw placement was rated according to Gertzbein and Robbins classification, with Grade A and B being considered accurate. Results: A total of 324 screws were evaluated within the trial. 223 screws were inserted using 2D fluoroscopy and 101 using navigation. 88.8% of screws were placed accurately in the fluoroscopy group, while 91.1% of the screws were placed accurately using navigation (p = 0.7). Conclusion: The use of navigation for pedicle screw placement facilitated higher accuracy rates compared to the use of fluoroscopy, though no significant difference was found. These results suggest that the choice of intraoperative imaging technique may have an influence on accuracy of screw placement in the thoracolumbar spine. Further evaluation of prospective randomized data should be performed. Also, other surrounding parameters should also be considered when choosing an intraoperative imaging technique.

ID: 734

A050: 3D-printed titanium cages for anterior and lateral lumbar interbody fusion result in excellent fusion rates one year after surgery

Anna-Katharina Calek ¹ , Bettina Hochreiter ¹ , Aaron Buckland ²

¹ Balgrist University Hospital, Zurich, Switzerland,

² Spine and Scoliosis Research Associates Australia, Melbourne, Australia

Introduction: Interbody composition is a key factor in the success of spinal fusion surgery. While the use of three-dimensional printed titanium (3DPTi) has been well established in other orthopaedic applications, little data exists when comparing to fusion rates with well-established polyetheretherketone (PEEK) or milled titanium alloy. The aim of this study was to determine the fusion rate in patients undergoing anterior lumbar interbody fusion (ALIF) and/or lateral lumbar interbody fusion (LLIF) with titanium cages. Material and Methods: Retrospective analysis of consecutively enrolled skeletally mature patients who underwent ALIF and/or LLIF interbody fusion for degenerative or deformity pathologies utilizing 3DPTi cages between 2020 and 2022 from a single surgeon spine registry. Fusion rate at 1-year follow-up was assessed by computed tomography (CT) scans and graded by Lenke-Bridwell classification. Flexion-extension lateral radiographs were assessed at 1-year postoperatively and fusion confirmed if < 5 degrees range of motion was detected through the fused segment. Perioperative metrics including bone graft type, operative time, estimated blood loss, revisions within the first postoperative year, and clinical outcome assessed by the Oswestry Disability Index (ODI) were analyzed. Results: Seventy-three patients, with 130 fusion levels with 3DPTi cages were identified. 71.2% of patients were treated for degenerative pathologies, 24.7% for deformity pathologies and 4.1% for pseudoarthrosis. 5.5% of patients underwent a revision procedure with 3DPTi cages. Overall, 99.2% of interbody levels were fused on CT at 1-year postoperatively. On flexion-extension radiographs, all levels were deemed to be fused. Five patients (6.8%) required an additional surgery within the first two years. No revisions were required for cage subsidence/migration, or pseudoarthrosis. Median ODI significantly improved at 1-year postoperatively compared to baseline (median baseline ODI: 46; 1-year ODI: 22, p = 0.001). Conclusion: 3DPTi cages for ALIF and LLIF result in excellent fusion rates at one year postoperatively without the need for rhBMP-2.

ID: 2550

A051: Using natural language processing to extract procedural information from 6,000 lumbar spine surgery notes

Mert Dagli ¹ , Yohannes Ghenbot ¹ , Daksh Chauhan ¹ , Hasan Ahmad ¹ , Ryan Turlip ¹ , William Welch ¹ , Ali Ozturk ¹ , Jang Yoon ¹

¹ University of Pennsylvania Perelman School of Medicine, Philadelphia, United States

Introduction: The accurate extraction of procedural information from operative notes is critical for clinical research and quality control in surgical practice. Objectives: This study aimed to develop and internally validate a natural language processing (NLP) algorithm capable of accurately identifying lumbar diskectomies involving two or fewer disks, extracting the specific levels of diskectomy, and quantifying the number of disks operated on. Secondary objectives included the extraction of similar data for additional procedures such as laminectomy, foraminotomy, facetectomy, and posterior fusion with instrumentation. Methods: We utilized a dataset, including operative notes extracted by our institutional Data Analytics Center (DAC), specifically targeting lumbar decompression surgeries between January, 2019 and September, 2023. The NLP algorithm, rooted in a rule-based framework, employed regular expressions and predefined spinal order functions to parse and classify surgical procedures within operative notes. After pre-processing, fuzzy regex matching was applied to identify procedure-specific phrases while handling slight variations in nomenclature. To address inherent limitations of a rule-based system in recognizing complex sentence structures and contextual nuances, a transformer-based model, specifically OpenAI's GPT-4 Turbo gpt-4-1106-preview Application Programming Interface (API), was integrated. Performance metrics such as accuracy, sensitivity, precision, AUC-ROC, and F1-score, along with their 95% confidence intervals (CI), were calculated using a bootstrapping method with 10,000 resamples. Results: Using the DAC dataset with 6,000 records, the pipeline was able to identify 1,955 diskectomies involving two or fewer disks, extracting procedure type, spinal levels and number of disks. Internal validation of the NLP algorithm was conducted on 162 records. The algorithm correctly identified all diskectomies. During the first step, level strings were accurately extracted in 159 records. Challenges arose with the remaining records, where the rule-based model's lack of contextual depth led to inaccuracies in level extractions (3/162). After the evaluation step with GPT-4 Turbo all conflicts were resolved. Conclusions: The GPT-4 Turbo augmented NLP algorithm showcased exceptional performance in parsing complex surgical records and accurately extracting procedural details with high precision without fatigue, suggesting a path toward automating clinical data extraction that may render manual review obsolete.

ID: 144

A052: 1-year ODI predicts return-to-work at 2 years among employed patients undergoing lumbar spine surgery for grade ii spondylolisthesis - A quality outcomes database study

Michael Tawil ¹ , Kai-Ming Fu ² , Marc Prablek ¹ , Timothy Yee ¹ , Anthony di Giorgio ¹ , Alysha Jamieson ¹ , Vivian Le ¹ , Jay Turner ³ , Juan Uribe ³ , Anthony Asher ⁴ , Domagoj Coric ⁴ , Michael Virk ² , Christopher Shaffrey ⁵ , Oren Gottfried ⁵ , Eric Potts ⁶ , Mohamad Bydon ⁷ , Michael Wang ⁸ , Paul Park ⁹ , Steven Glassman ¹⁰ , Kevin Foley ¹¹ , Cheerag Upadhyaya ¹² , Mark Shaffrey ¹³ , Erica Bisson ¹⁴ , Dean Chou ¹⁵ , Praveen Mummaneni ¹

¹ UCSF, San Francisco, United States,

² Cornell, New York, New York, United States,

³ Barrow, Phoenix, United States,

⁴ Cnsa, Charlotte, United States,

⁵ Duke, Durham, United States,

⁶ Goodman Campbell brain and spine, Carmel, United States,

⁷ Mayo, Rochester, United States,

⁸ University of Miami, Miami, United States,

⁹ Univeristy of Michigan, Ann Arbor, United States,

¹⁰ Norton, Louisville , United States,

¹¹ Semmes Murphey, Memphis, United States,

¹² UNC, Chapel Hill, United States,

¹³ UVA, Charlottesville, United States,

¹⁴ University of Utah, Salt Lake City, United States,

¹⁵ Columbia University, New York, New York, United States

Introduction: Returning to work is a critical measure of patient function and success after surgery. In this study, we aimed to identify predictors of return-to-work status following lumbar spine surgery for grade II spondylolisthesis. Material and Methods: We queried the Quality Outcomes Database for employed patients who underwent lumbar spine surgery for grade II spondylolisthesis. Return-to-work status was assessed if patients returned to work at any time within 24 months postoperatively. Results: Among 400 patients who underwent surgery for grade II spondylolisthesis, 170 were employed before surgery. Return-to-work data was available for 153 patients at 1 year postoperatively and 159 patients at 2 years postoperatively. 131 patients (85.6%) returned to work by 1 year and 140 patients (88.1%) returned to work by two years. Patients who returned to work had lower ODI and higher EQ5D scores at baseline compared to those who did not return to work. Demographic characteristics did not differ between these groups. RTW patients had lower VAS-leg pain scores, higher EQ5D scores, and were more likely to be satisfied with surgery at 1 year post-operatively (p = 0.004). In multivariate analysis, lower ODI at 12 months independently predicted return-to-work status by 24 months (OR 1.2, p = 0.04). Conclusion: Patients with grade II spondylolisthesis have a high rate (88%) of returning to work after surgery. Lower ODI scores at 1 year predict return-to-work status by two-years postoperatively.

ID: 513

A053: Robotic vs navigation based spine surgery: early insights on outcomes and cost savings from a matched patient cohort

Pirateb Sundaram¹, Yang Yao Daniel Peh², Wenjin Jane Poh², Arun-Kumar Kaliya-Perumal², Jacob Oh¹

¹ Tan Tock Seng Hospital, Division of Spine Surgery, Department of Orthopaedic Surgery, Singapore, Singapore,

² Nanyang Technological University, Lee Kong Chian School of Medicine, Singapore, Singapore

Introduction: Spine surgery has experienced significant advancements, particularly with the integration of robotic systems that enhance surgical techniques and patient outcomes. This study aims to compare robotic-assisted and navigation-based spine surgery in single- and double-level interbody fusion cases with respect to operative duration, intraoperative blood loss, and length of hospital stay. A comparison on the costs of surgery with both systems along with other factors that influence healthcare costs are evaluated in this study. Material and Methods: A retrospective cohort study was conducted at a tertiary institution on patients who underwent single- and double-level transforaminal and oblique lateral lumbar interbody fusion (TLIF and OLIF) surgeries by a single surgeon with the use of robotic-assisted spine surgery between October 2022 and May 2024, and patients who underwent navigation-based spine surgery prior to the introduction of robotic system in the institution between January 2018 and December 2020. The first 20 cases that underwent robotic surgery were excluded to account for its learning curve. Patient groups were matched for analysis based on the number of levels of fusion and surgical approach (TLIF or OLIF). Data on demographics, comorbidities, diagnoses, operative duration, intraoperative blood loss, and length of hospital stay were collected and analyzed. Results: There were 36 robotic cases and 45 navigation cases in our matched analysis. 32 (71%) of the navigation cases were done via a minimally invasive surgical (MIS) approach while all robotic cases were done via a MIS approach. The mean operative duration for single and double level OLIF cases were significantly shorter in robotic surgery compared to use of the navigation system by 50 and 62 minutes respectively (p < 0.05). The blood loss was lower with robotic surgery in double-level TLIF and single- and double-level OLIF cases with robotic surgery, although not reaching statistical significance. The length of stay was also shorter in single-level TLIF and double-level OLIF cases, but not reaching statistical significance. Cost analysis indicated significant savings with robotic surgery, amounting to $4,188.70 per patient for 2-level OLIF cases when employing robotic systems. Conclusion: The findings of this study suggest that robotic-assisted spine surgery could offer advantages over navigation-based techniques in terms of reducing operative duration, minimizing intraoperative blood loss, and shortening the length of hospital stay. Robotic surgery allowed for ease of MIS approach. These benefits may contribute to improved patient outcomes, reduced perioperative complications and decreased healthcare costs. With 200 such cases performed annually, potential savings could reach S$837,740 per year. As robotic technologies continue to evolve, their integration into spine surgery practice is justified, presenting a promising future for improved patient outcomes and cost effectiveness.

ID: 2079

A054: Advancements in artificial intelligence for low back pain integrating automated muscle analysis and disc identification

Fabrizio Russo ¹ , Gianluca Vadalà ¹ , Giuseppe Francesco Papalia ¹ , Luca Ambrosio ¹ , Federico D'Antoni ² , Mario Merone ² , Rocco Papalia ¹ , Vincenzo Denaro ²

¹ Campus Bio-Medico University Hospital Foundation, Rome, Italy,

² Campus Bio-Medico University of Rome, Rome, Italy

Introduction: Low back pain (LBP) is an endemic musculoskeletal condition and a global leading cause of disability1. In the pursuit of enhancing early diagnostic and treatment capabilities, artificial intelligence (AI) has emerged as a transformative tool2. In this study, we developed a fully automated algorithm for disc identification and lumbar paraspinal muscle segmentation from lumbar magnetic resonance imaging (MRI) scans. Material and Methods: Automated identification and spatial analysis of intervertebral discs: After Gaussian filtering for noise reduction, a 2D isotropic filter is applied. Column-wise average intensity is calculated, allowing to determine a reference coordinate for the spinal canal by resolving argmax over the intensity columns. The spinal canal coordinates guide a composite function for curve identification. Utilizing intensity, a linear approximation is made for the upper 20% of image rows, followed by a 3rd-degree polynomial for the remaining curve. The resulting shape is used to create a mask, shifting it leftwards to select the region encompassing the vertebrae and discs based on intensity. Extraneous columns are removed. Similarly, total intensity per pixel row is calculated, identifying intensity peaks (vertebrae) and valleys (discs). Local minimal intensity reveals the vertical coordinates of intervertebral discs. Knowing each disc center facilitates identifying the axial slice corresponding to each disc. Paraspinal muscle segmentation: The focus then shifts to the strategically chosen L4-L5 level. A U-Net architecture is employed for the automated segmentation of lumbar paraspinal muscles. This sophisticated algorithm processes MRI data, distinguishing between muscle and non-muscle structures. The outcome is a precise delineation of muscle boundaries, forming the foundation for subsequent analyses. Adipose Infiltration Assessment: The second segmentation task involves distinguishing between muscle and fat subregions within previously predicted regions of interest (ROIs). A visible contrast difference between muscle and fat tissues is leveraged, employing an intensity-based segmentation strategy followed by region-based spatial refinement. Otsu’s thresholding method is applied to the paraspinal ROI. The raw fat mask is then propagated using a recursive empirical region-growing algorithm, exploring boundary pixels for high-contrast regions in a local neighborhood. This process applies iteratively until no substantial area increase is detected. Hyperparameters are optimized through grid search, enhancing accuracy metrics for the final setup. T2-weighted lumbar MRI scans of 91 subjects were considered for the preliminary investigation, and images of 100 patients from a public dataset were utilized for further validation. Results: We achieved accurate automated disc identification (100%) and subsequent selection of axial slices. At the L4-L5 level, the U-Net-based muscle segmentation achieved an average DICE score > 95% on the internal dataset, and > 94% on the public dataset. Adipose infiltration assessments complemented these findings, contributing to a comprehensive understanding of the musculoskeletal dynamics. Conclusion: This detailed methodology integrates cutting-edge AI techniques, revolutionizing LBP management. The automated disc-to-axial slice association streamlines the process, allowing for targeted analysis at the L4-L5 level. The implications for personalized treatment plans and the broader landscape of AI-enabled healthcare interventions will shed a new light on LBP treatment.

OP07: Outcomes and Epidemiology

ID: 2831

A055: Familial predisposition for acute low back pain: longitudinal follow-up data from 20279 families

Jason Cheung ¹ , Prudence Wing Hang Cheung ¹

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

Introduction: Acute low back pain (LBP) is one of the most devastating and common problems worldwide. Its prevalence and risk factors are unclear from general population studies. Utilizing a large population cohort, we identified a standardized set of risk factors for acute LBP. The investigators have studied a FAMILY Cohort in which 20279 families were recruited with a panel of risk factors that are investigated for its predisposition for acute LBP. Material and Methods: 46001 individuals from 20279 families were recruited for longitudinal follow-up. Each sampling unit was from a family living in the sample household. Through stratified random sampling of households from all districts in the territory, a population-wide survey was conducted. In this FAMILY Cohort, individuals completed face-to-face interviews during 2 waves of household visits. This comprises of a standardized panel of parameters including age, sex, body mass index, medical history (diabetes mellitus, hypertension, hypercholesterolaemia, coronary heart disease), social history (smoking, drinking and drug use, educational level, occupation and type of work involved), International Physical Activity Questionnaire (IPAQ), life stress event, highly-sensitive C-reactive protein and HbA1C. Acute LBP was defined as having LBP in the past 12 months. Poisson regression models were used to identify risk factors for acute LBP with estimated relative risks and 95% confidence interval, adjusted for age, gender and body fat percentage. Results: A total of 42471 subjects (92.3%) responded and 14624 (31.8%) reported acute LBP with a predilection for men (61.9%). The mean age was 49.4 (SD 16.5) years and mean BMI was 23.9 (SD 3.8). About half (52.2) of the surveyed population had moderate level of physical activity but the reported acute LBP was higher in the low-level physical activity category (36.2%). 22.3% (n = 9458) of individuals had simultaneously 1 or more family member experiencing acute LBP. Among those households reporting acute LBP, those with family size of 4 people reported 69.4% having multiple members with acute LBP. Up to 75.1% was noted in 5-person households and 75.9% in 6-person households. Poisson regression model (wald X² 57.084, p < 0.001) reveals the following risk factors: family member experiencing acute LBP at same household (RR 3.059, 95% CI 2.868 - 3.263) p < 0.001), male (RR 1.467, 95% CI 1.322 - 1.628, p < 0.001), ever smoker (RR 1.126, 95% CI 1.031 - 1.229, p = 0.008), stress event in past 12 months (RR 1.289, 95% CI 1.206 - 1.376, p < 0.001), age (RR 1.007, 95% CI 1.004 - 1.010, p < 0.001) and occupation with high physical demand (RR 1.364, 95% CI 1.266 - 1.470, p < 0.001). Conclusion: In the general population, risk factors for acute LBP were the family factor, increased age, male gender, more physically demanding work, ever smoker and life-stress event in recent 12 months. We recommend preventive measures on modifiable factors including exercise, diet modification and smoking cessation, whereas support should be offered to those partaking in labour-intensive jobs and those who had recent stressful life events. This is especially important for those with family members suffering from acute LBP.

ID: 114

A056: Gender differences in outcomes in patients treated for thoracolumbar burst fractures without neurological deficits: prospective international multicenter study

Charlotte Dandurand ¹ , Marcel F. Dvorak ¹ , Cumhur Oner ² , Dimitri Hauri ³ , Klaus Schnake ⁴ , Alex Vaccaro ⁵ , Lorin Michael Benneker ⁶ , Gregory Schroeder ⁵ , S. Rajasekaran ⁷ , Mohammad El-Sharkawi ⁸ , Rishi Kanna ⁷ , Eugen Cezar Popescu ⁹ , Jin Tee ¹⁰ , Andrei Joaquim ¹¹ , Harvinder Singh Chhabra ¹² , Ulrich Spiegl ¹³ , Richard Bransford ¹⁴

¹ University of British Columbia, Vancouver, Canada,

² University Medical Centers, Utrecht, Netherlands,

³ AO Innovation Translation Center, Davos, Switzerland,

⁴ Center for Spinal and Scoliosis Surgery, Malteser Waldkrankenhaus St. Marien Erlangen, Erlangen, Germany,

⁵ Thomas Jefferson University, Philadelphia, United States,

⁶ University of Bern, Bern, Switzerland,

⁷ Ganga Hospital, Coimbatore, India,

⁸ Assiut University, El Fateh, Egypt,

⁹ Prof. Dr. N. Oblu” Emergency Hospital, Iasi, Romania,

¹⁰ The Alfred Hospital, Melbourne, Australia,

¹¹ State University of Campinas, Campinas-Sao Paulo, Brazil,

¹² Sri Balaji Action Medical Institute, New Delhi, India,

¹³ University of Leipzig, Leipzig, Germany,

¹⁴ University of Washington, Seattle, Canada

Background: Investigations on the relationship between gender and outcomes after spinal surgery have produced mixed results. However, many studies found that males have better scores or outcomes after spinal surgery. Studies have shown that women report worse health outcomes than men, not only after medical procedures, but also in population norm studies. A recent systematic review analyzing differences between genders showed that most studies (76.6%) report differences in outcomes after spinal fusion. This review identified a clear knowledge gap with only 6.3% of studies (retrospective) reporting on traumatic spinal pathologies. Considering the burden on patients and society related to thoracolumbar burst fractures, it is essential to explore gender differences in outcomes to ensure optimization of treatment. The goal of this study was to assess if any gender differences exist in patients treated for thoracolumbar (TL) burst fractures without neurological deficits, specifically in terms of Oswestry Disability Index (ODI) improvement. Secondarily, we aimed at assessing if gender differences exist in baseline characteristics, treatment selection and other patient reported outcomes. Methods: Patient demographics, clinical and outcome data were prospectively collected. Primary endpoint was defined as time to achieve minimal clinically important difference (MCID) in Oswestry disability index (ODI). In exploratory analysis, we defined improvement in ODI as reaching minimal disability. Results: Genders were similar in terms of baseline characteristics except working status and similar in terms of injury characteristics as well as treatment selection and timing. Surgically treated females showed a statistically faster achievement of MCID in ODI compared to males (14 days, 95%CI 14.0-28.0 vs 28 days, 95% CI 15.0-34.0, p = 0.009). On multivariable model, nonoperatively treated female patients had a lower chance for achieving improvement in the ODI than nonoperatively treated male patients (HR 0.55, 95% CI: 0.32-.96, p = 0.036). Females had a longer median time to achieve minimal disability (102.0 days, 95% CI: 76.0; 131.0 vs 62.0 days, 95% CI: 51.0; 72.0, p = 0.008). Nonoperative females had a longer median time to achieve minimal disability (130.0 days, 95% CI: 82.0-185.0 vs 61.0 days, 95% CI: 47.0-76.0, p = 0.048). On multivariable model, nonoperative females had a lower chance for achieving minimal disability than nonoperatively treated males (HR 0.55, 95% CI 0.31-0.98 p = 0.042). Conclusion: This unique study, to our knowledge, is the largest and only prospective study to date to assess gender difference in thoracolumbar spinal trauma. We present new and unique findings from a prospective international and multicenter study. This study provides novel data showing that gender differences exist in TL burst fractures in neurologically intact patient. Females do worse within nonoperative management compared to males. In addition, female patients do better with operative management than nonoperative management in achieving MCID while this was not observed in male patients. Thus, females also seem to benefit to a greater extent from surgical management. The results highlight the importance of personalized treatment based on gender. Future studies should assess gender differences in other traumatic spinal pathologies.

ID: 2352

A057: Growing impact of osteoporotic vertebral fractures: an epidemiological analysis in a tertiary hospital

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 University of 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: Population aging is associated with a loss of bone density, leading to an increased frequency of fractures, with osteoporotic vertebral fractures (OVFs) being the most prevalent. The socioeconomic impact of OVFs is significant, as they are linked to various adverse outcomes. This study aims to characterize a series of patients with OVFs admitted to a tertiary hospital. Material and Methods: Epidemiological, retrospective follow-up study of patients admitted to a tertiary hospital for acute OVFs over the period of one year. Patients with a confirmed diagnosis of acute OVF via magnetic resonance imaging (MRI) were included. Demographic variables, data related to OVFs and other osteoporotic fractures, as well as the treatments received, were analyzed. Results: A total of 222 patients were included in the study, corresponding to an acute OVF-related hospital admission every 1.6 days, with an incidence of 2.3 per 1,000 person-years at risk. These cases accounted for 15.9% of total admissions to the Orthopaedics and Traumatology Department during the study period and 16.8% of the department's total budget. The mean age of the patients was 76.2 ± 9.8 years, with the majority being women (176; 79.3%). The average Charlson Comorbidity Index score was 4.2 ± 1.7, corresponding to a 10-year survival estimate of 47.2%. Despite 29 patients (13.1%) having a prior diagnosis of OVF and 79 (35.6%) having a history of other fragility fractures, only 43 (19.4%) were receiving anti-osteoporotic treatment at the time of admission. A total of 511 OVFs were diagnosed, 321 (62.8%) of which were acute. The most common site for primary acute OVF was at the T12-L1 level (120 cases; 54.0%). According to the AO Spine-DGOU classification, OF2 fractures were the most prevalent, accounting for 132 cases (59.5%). The most frequent mechanism of injury was a fall from the patient’s own height (160 patients; 71.1%), followed by overexertion (39 patients; 17.3%). Conservative treatment was used in 163 patients (73.4%), while 59 patients (26.6%) underwent surgery. Conservative treatment led to better pain resolution at the end of follow-up (84.9% vs. 66.1%, p = 0.004) and a lower incidence of subsequent OVFs (3.3% vs. 15.5%, p = 0.003), at nearly three times lower direct costs per patient (€3,426.85 vs. €10,064.44). The median length of stay was 4.0 [3.0-6.0] days, nearly double for those undergoing surgery (11.0 [8.0-14.0] vs. 5.0 [4.0–8.0] days). During follow-up, 15 patients (7.1%) died. Conclusion: This study reveals a high incidence of OVFs with significant morbidity and mortality. These findings highlight the significant clinical and epidemiological challenge that OVFs currently pose. The results underscore the need for preventive and pharmacological measures aimed at reducing the occurrence of these fractures.

ID: 856

A058: Global orthopedic spine research in LMICs: a scoping review

Jacob Matityahu ¹ , Haley Nadone ¹ , Kylen Soriano ¹ , Sohaib Hashmi ¹ , Hansen Bow ² , Michael Oh ² , Don Park ¹ , Yu-po Lee ¹ , Nitin Bhatia ¹ , Hao-Hua Wu ¹

¹ University of California, Irvine, Department of Orthopaedic Surgery, Global Spine Research Initiative, Orange, United States,

² University of California, Irvine, Department of Neurological Surgery, Orange, United States

Introduction: Spinal disorders have a profound impact on global health, especially in low- and middle-income countries (LMICs) where access to spine surgery is often limited. This scoping review aimed to identify gaps in global orthopedic spine research to guide future research priorities by assessing the quality and quantity of spine literature in low- and middle-income countries (LMICs). Material and Methods: Using the 6-stage Arksey and O'Malley framework for scoping reviews, we analyzed orthopedic spine studies conducted in LMICs from 2004 to 2014. Studies were categorized based on geographic location, anatomical region, study type, condition etiology, population size, and level of evidence. Results: Out of 22,714 searches, 118 studies met the inclusion criteria. Of these, 68.6% were from LMICs in South Asia, 17.8% from sub-Saharan Africa, 11.0% from the Middle East and North Africa, 1.7% from East Asia and the Pacific, and 0.8% from Europe and Central Asia. Nearly half of the studies from South Asia (48.1%) focused on traumatic spinal conditions, representing the highest proportion of such studies compared to other regions. Traumatic conditions were the predominant research focus across all regions, with 30.8% of studies from the Middle East and North Africa and 28.6% from sub-Saharan Africa falling into this category. The studies mainly addressed therapeutic (55.1%), epidemiological (22.9%), and diagnostic aspects (13.6%) of spinal conditions. Only 5% of studies were on minimally invasive surgery (MIS), all of which were conducted in South Asia, with 83% of these classified as Level 4 evidence. Overall, only 5% of studies achieved Level 1 or 2 evidence. Of the 118 studies, 45 were prospective and 16 included a control group. Level 1 and 2 studies were less likely to be epidemiological and more likely to be diagnostic, prognostic, or systematic reviews/meta-analyses (0% vs. 24.1%; 33.3% vs. 12.5%; 16.7% vs. 6.3%; 16.7% vs. 0%; p = 0.01). Academic affiliations were present in 88.1% of the studies, and collaboration between LMIC and high-income country (HIC) researchers was noted in 7.6% of studies, but this collaboration did not correlate with higher levels of evidence. Conclusion: The review highlighted a significant shortage of high-level evidence in spine studies from LMICs, with very few achieving Level 1 or 2 evidence. There is a marked regional disparity, with South Asia contributing the majority of the studies, while sub-Saharan Africa is underrepresented. Most studies focused on traumatic conditions, with minimally invasive surgical techniques rarely explored. This scoping review underscores the need for improved research capacity and emphasizes the importance of prioritizing high-quality research in LMICs to address the global burden of spine disorders.

ID: 2764

A059: Nationwide trends in survival after surgery for metastatic spine disease in Finland

Leevi Toivonen ¹ , Ville Ponkilainen ¹ , Jussi Repo ¹ , Ville Mattila ¹

¹ Tampere University Hospital, Tampere, Finland

Introduction: Ageing populations and advancing oncological treatments increase the number of cancer patients. As a result, metastatic spine disease (MSD) is expected to manifest at an accelerating pace. In MSD, surgery has its role in reducing neurological deficits resulting from metastatic spinal cord compression and in the management of unstable spine lesions. The burden of surgery needs to be weighed against the frailty and potentially short life expectancy of the patients. Population-based data on survival after surgery for MSD are limited, but they are required for optimizing treatment solutions in this population. Material and Methods: Data were derived and combined from three nationwide, population-based registers: Finnish Cancer Register (FCR), Finnish National Hospital Discharge Register, and Finnish Cause of Death Register. All individuals stored in FCR by 2021 were screened for spine surgery related hospitalizations between 1997-2020. MSD surgeries were identified on the basis of diagnosis and procedural codes in the hospitalizations and subsequent FCR records. Incidence rates of surgery for MSD were calculated per 100,000 inhabitants and adjusted for age and sex. Kaplan–Meier survival estimates (with 95% confidence intervals) were calculated based on the first MSD surgery per patient. Results: The data included 1,827 patients who underwent 1,991 surgeries. The mean age of the patients was 65 years (SD, 55-73), and 59% were men. The most common primary cancer diagnoses were prostate cancer (n = 275, 13.8%), breast cancer (n = 217, 10.9%), and myeloma (n = 212, 10.6%). The age- and sex-adjusted incidence of MSD surgeries increased from 1.05 per 100,000 person-years in 1997 to 1.90 per 100,000 person-years in 2018. Over the same period, 6-month survival remained stable between 56% (46%-68%) in 2006 and 76% (68%-85%) in 2004 and 2011. Surgeries increased most among patients aged 60-79 years. The survival probabilities were 56% (53%-58%) at 1-year, 42% (40%-45%) at 2-years, 26% (24%-28%) at 5-years, and 17% (16%-20%) at 10-years. The 1-year survival probability ranged from 81% (74%-88%) in patents aged under 40 years to 48% (40%-57%) in patients aged over 80 years. The 1-year survival probability was highest in patients with breast, 73% (67%-80%), and lowest in kidney cancer, 42% (35%-50%). Conclusion: Finnish nationwide data show a modest increase in surgeries for MSD between 1997-2020, and simultaneously a stable estimated survival postsurgery. In the study period, MSD surgeries in Finland were mainly targeted at acute spinal cord compression. In this setting, majority of patients have a short life-expectancy, but some will survive several years, highlighting the need to minimize the surgical burden but still choose durable surgical strategies.

ID: 814

A060: Prediction of fragility fracture risk using computed tomography-based trabecular density (Hounsfield Units): a retrospective cohort study

Gonzalo Kido ¹ , Sofia Beltrame ¹ , Ivan Kalejman ¹ , Julio Bassani ¹ , Matias Petracchi ¹ , Marcelo Gruenberg ¹

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

Introduction: Osteoporosis is characterized by decreased bone mass and quality, which predisposes individuals to fragility fractures. While dual-energy X-ray absorptiometry (DXA) is the gold standard for assessing bone mineral density (BMD), many patients with fragility fractures can present with non-osteoporotic BMD values. Moreover, conditions such as obesity and degenerative diseases may complicate accurate DXA measurements. Lumbar trabecular attenuation measured in Hounsfield Units (HU) by computed tomography (CT) has good correlation with DXA T-scores, making it a potential alternative for diagnosing osteoporosis and assessing fracture risk in these patients, especially using a cut-off of 90 HU. The aim of this study is to evaluate the independent predictive capacity of osteoporosis (HU < 90) measured by CT for fragility fractures over ten years. Materials and Methods: This retrospective cohort study included patients aged over 60 treated at the Italian hospital of Buenos Aires, who underwent CT scans of the abdomen or lumbar/thoracolumbar spine between January 2010 and December 2012. Follow-up continued until the end of 2022, with fragility fractures as the primary outcome. BMD measurements using HU were performed by two orthopedic specialists blinded to fracture outcomes. Other variables were extracted from electronic medical records, focusing on fragility fractures. A researcher, also blinded to BMD measurements, manually verified the accuracy of the primary outcome. We explored the independent predictive capacity of osteoporosis as documented by CT using an adjustment model similar to Lee et al., adding body mass index (BMI), sarcopenia (defined as BMI below 34.4 cm²/m² in women and 45.4 cm²/m² in men), and psychotropic drug use. Our main outcome was osteoporotic fracture, considering death as a competing event. Results: A total of 587 patients were analyzed. During follow-up, 80 patients (13.63%) experienced osteoporotic fractures, with 19 (23.75%) classified as vertebral fractures. In bivariate analysis, patients with BMD < 90 HU had a 222% increased risk of fragility fracture (HR 3.22, 95% CI 2.07-5.01; p < 0.001). After adjusting for age, sex, BMI, prior fractures, corticosteroid use, bisphosphonate use, creatinine clearance < 60 mL/min/1.73 m², smoking, alcohol use, rheumatoid arthritis, psychotropic drug use, and sarcopenia, this association remained significant (HR 2.73, 95% CI 1.55-4.83; p = 0.001). Conversely, sarcopenia showed no significant association with the development of osteoporotic fractures (bivariate HR: 0.86; CI 0.54 to 1.38; p = 0.549; multivariate HR: 0.82; CI 0.49 to 1.36; p = 0.496). Conclusion: This study confirms that BMD < 90 HU measured by CT is an independent predictor of osteoporotic fracture risk over ten years, providing evidence supporting the predictive value of established prognostic factors.

ID: 1204

A061: The impact of smoking on low back pain and disability - a propensity score matched analysis

Lukas Schönnagel ^1,2 , Bernhard Hoehl ² , Nima Taheri ² , Friederike Schömig ² , Luis Becker ² , Paul Köhli ² , Hendrik Schmidt ² , Pumberger Matthias ²

¹ Universitätsmedizin Charite, Berlin, ² Universitätsmedizin Charite, Berlin, Germany

Objective: Low back pain (LBP) is a predominant cause of disability worldwide, significantly diminishing quality of life and exerting pressure on healthcare resources. While the multifactorial nature of LBP encompasses a range of risk factors, the relationship between smoking and LBP, especially in terms of severity and disability, has not been fully explored. The goal of this study is to evaluate the impact of smoking on LBP in a propensity score matched analysis. Material and Methods: This study is part of the ongoing DFG Research Unit FOR5177. Patients between 18 and 64 years of age were prospectively enrolled. The severity of LBP was assessed with the von Korff questionnaire, from which the pain intensity and the disability score, ranging from 0 to 100 each, were calculated. Disability was additionally assessed with the Roland Morris Disability Scale (RMDS), ranging from 0 to 24. Smoking was stratified by the number of pack years (PY) and if patients were actively smoking or not. Propensity score matching was performed regarding age, sex, body mass index (BMI), drinking, and physical activity, measured by the International Physical Activity Questionnaire (IPAQ), and depression, measured by the patient health questionnaire (PHQ4). Three matched groups were evaluated: Never-smoking vs. smoking patients with any amount of PY, 0 to < 10 PY, and ≥ 10 PY. A multivariable linear regression model was used to further analyze the relationship between pain, disability and smoking. Results: A total of 645 patients (55.7% female) with a mean age of 41 (IQR 32 - 53) were included, of which 84 (12.2%) patients smoked. The mean pain intensity and disability score were 33.3 (IQR 20 - 50) and 13.3 (IQR 3.3 - 30), respectively. In the propensity score-matched analysis, patients with 0 to < 10 PY did not show a significant increase in the pain-associated outcomes, while patients with ≥ 10 PY demonstrated a significant increase in pain severity (43.3 vs. 30.0, p = 0.024, r = 0.22 ), disability (26.7 vs. 10.0, p = 0.01, r = 0.27) and the RMDS (6 vs. 3, p = 0.02, r = 0.22). The multivariable linear regression also demonstrated a significant relationship between PY and LBP-related outcomes, while smoking status alone was not significant. For each PY, the pain intensity increased by 0.35 (95% CI: 0.11 - 0.59, p = 0.01), and the subjective disability score by 0.30 (95% CI: 0.06 - 0.55, p = 0.017). Conclusion: This study reveals a dose-response relationship between smoking and increased severity of LBP, strengthened through a robust propensity score analysis. The findings support enhanced patient education and suggest that incorporating smoking cessation interventions into LBP management could benefit both individual and public health.

ID: 1127

A062: Comparative analysis of the quality of life of Brazilian children with early onset scoliosis using the EOSQ-24 and CHQ PF-50 questionnaires

Rodrigo Goes ¹ , Wesley Martins ¹ , Patricia Fucs ¹ , Maria Fernanda Silber Caffaro ¹ , Alberto Gotfryd ¹ , João Tomás Garcia ¹ , Robert Meves ¹

¹ Santa Casa de São Paulo, São Paulo, Brazil

Introduction: Early-onset scoliosis (EOS) involves a group of diverse etiologies and natural history, which often require repetitive surgeries in childhood and adolescence. In recent years, there has been a growing interest in assessing the quality of life of children with EOS. Therefore, the study aimed to apply and correlate the Early-Onset Scoliosis-24 Questionnaire (EOSQ-24) with the Childhood Health Questionnaire (CHQ-50 PF). Material and Methods: Cross-sectional study with a population composed of caregivers of patients with EOS. The sample consisted of 72 patients, with pre-defined inclusion and exclusion criteria. The Portuguese version of the EOSQ-24 and CHQ-50 PF both (0-100) scores were applied in three treatment centers by two separate research assistants. The EOSQ-24 assesses the subjective response of children with EOS from their parent's point of view. The clarity and understanding of the EOSQ-24 translated into Portuguese were assessed using the five-point Likert scale. The CHQ is a self-administered questionnaire or parental proxy assessment of the psychological and social status of children aged 5 to 18 years. This questionnaire measures a child's general health status and was developed for researchers and clinicians to study children's functional activities. The aim of this study is to perform a comparative analysis of quality of life using the Early Onset Scoliosis 24-Item Questionnaire (EOSQ-24) and CHQ PF-50, already validated in Portuguese; taking into account surgical versus non-surgical groups, types of surgery and epidemiology of patients with IPE. Results: We evaluated 72 patients, 41 (56.9%) were female, with a mean age of 11.9+4.2 years. The most common scoliosis was of neuromuscular origin (32%). The CHQ questionnaire showed that family-related items had high scores. When comparing the analysis of quality of life, according to the CHQ-50 and EOSQ-24, in surgical cases vs. non-surgical cases, no statistically significant difference was found between the groups. The analysis of surgical cases, we compared whether quality of life was different between cases undergoing arthrodesis vs. non-arthrodesis. For most subcategories of the EOS-24 questionnaire, no statistically significant difference was identified, p > 0.05. However, for general health (Global Health), a difference was detected with higher values ​​in favor of the group that did not undergo arthrodesis, p = 0.047. Conclusion: In the general health subcategory of the EOS-24 questionnaire, a significant difference was detected, p = 0.047, for patients who did not undergo arthrodesis, characterizing this procedure as a factor that worsened the quality of life of patients with EOS. There were no other significant differences between quality of life, based on the EOSQ-24 and CHQ-50 questionnaires, in surgical and non-surgical cases.

ID: 1194

A063: A temporal analysis of the epidemiology of lower back pain in the United States

Nithin Gupta ¹ , Jagroop Doad ¹ , Rohin Singh ² , Derek Chien ³ , Matthew Cotroneo ³ , Daniel Reid ⁴ , Michael Cloney ⁵ , David Paul ²

¹ Campbell University School of Osteopathic Medicine, Lillington, United States,

² University of Rochester Medical Center, Department of Neurosurgery, Rochester, United States,

³ University of Rochester Medical School, Rochester, United States,

⁴ Conway Medical Center, Department of Orthopaedic Spine Surgery, Conway, United States,

⁵ University of Pittsburgh, Department of Neurosurgery, Pittsburgh, United States

Introduction: Low back pain (LBP) is a major contributor to lost wages and disability in the United States (US.) It is well known that LBP is associated with increasing age and sedentary lifestyle, thus given the population dynamics in the US, the incidence of LBP is expected to rise. Due to LBP's multifactorial causes, US epidemiological trends lack sufficient data. Therefore, this study aims to elucidate the sociodemographic and regional geographic variations in LBP incidence, prevalence, and burden in the United States from 2000-2019. Material and Methods: Descriptive epidemiological data including disability-adjusted life years (DALYs), incidence, and prevalence per 100,000 population from 2000-2019 were collected from the Global Burden of Disease database. State-level data regarding poverty, insurance and employment status were obtained from the US Government Census Bureau and US Department of Labor. Statistical significance was indicated by p < 0.05. Results: From 2000-2019, there was a 3.67%, 0.23%, and 2.93% decrease in LBP incidence, prevalence, and DALYs in the US, respectively. Regional analysis demonstrated the Midwest to have the greatest mean incidence, prevalence, and DALYs; with Midwestern females significantly more affected than females in other regions. Those aged 25-49 in the Midwest were impacted significantly more across all measures compared to age-matched populations in other regions. Nationally, there were no significant associations between unemployment and LBP. Poverty was inversely correlated with LBP incidence (R = -0.51, p = 0.04). Uninsured status was positively correlated with prevalence (ρ = 0.87, p < 0.01) and DALYs (ρ = 0.85, p < 0.01). Conclusion: There is data to support an overall reduction of the impact of LBP in the US, however disparities still remain. The Midwest region has greater rates for all measures compared to other US regions. Further, females and those aged 25-49 in the Midwest were more likely to be affected by LBP compared to counterparts in other regions. Future studies may seek to identify specific factors contributing to elevated LBP rates in the Midwest in order to guide targeted interventions to reduce the incidence and burden of LBP.

OP08: Imaging and Diagnostics 1

ID: 432

A064: Magnetic resonance imaging versus 18F-FDG-PET/CT in the detection of tuberculous spondylodiscitis: preliminary results from the Spinal TB X cohort

Julian Scherer ^1,2 , Ferdinand Oompie ¹ , Tessa Kotze ¹ , Friedrich Thienemann ¹

¹ University of Cape Town, Cape Town, South Africa,

² University Hospital of Zurich, Zurich, Switzerland

Introduction: Magnetic resonance imaging (MRI) is the current imaging gold standard for the radiological assessment of tuberculous spondylodiscitis, with a reported sensitivity and specificity of above 90%. Recently, a study showed that 18F-Fluorodeoxyglucose Positron Emission Tomography-computed Tomography (PET/CT), as a whole-body imaging modality, may produce comparable sensitivity but a better specificity than MRI in the detection of spondylodiscitis. Studies comparing the detection of tuberculous vertebral lesions between MRI and PET/CT are rare. In this preliminary analysis we assessed and compared the detection of lesions and the number of diseased vertebras per lesion caused by Mycobacterium tuberculosis between the two imaging modalities in 22 patients with microbiologically confirmed spinal tuberculosis (STB). Material and Methods: The Spinal TB X cohort (clinicaltrials.gov: NCT05610098) is an ongoing prospective cohort study describing the clinical phenotype of spinal TB using whole-body 18FDG-PET/CT (PET/CT) and whole-spine MRI at baseline with repeated PET/CT at six- and 12-months to monitor treatment respond. Results: At the time of submission, 82 patients were screened, of which 28 patients were enrolled and underwent both MRI and PET/CT. 22 patients had microbiologically confirmed STB (50% female, 45.5% HIV-infected, median age 47.5 years, IQR 23.8). Spinal skip lesions were detected by PET/CT in five patients (80% HIV-uninfected) whereas MRI detected spinal skip lesions in only one patient. Psoas abscess formation was detected by PET/CT in 15 patients (MRI 14 patients). The mean lesion count per patient was 1.3 (SD 0.6) on PET/CT and 1.1 (SD 0.4) on MRI. (Shapiro-Wilk < 0.001, p = 0.094). PET/CT identified an average of 2.9 diseased vertebras per lesion (SD 1.4), whereas MRI detected an average of 2.4 (SD 0.6) diseased vertebras per lesion. (Shapiro-Wilk < 0.001, p = 0.205). Conclusion: In our findings, we had a higher rate of lesion detection using PET/CT including spinal skip lesions, compared to the current imaging gold standard. Further, more diseased vertebras per lesions were detected by PET/CT compared to MRI. PET/CT might be an advantageous imaging modality to quantify the extent of disease in patients with STB. With increasing sample size, we aim to confirm these findings.

ID: 2277

A065: International multicenter validation of the AO Spine DGOU osteoporotic fracture classification system: reliability and reproducibility among clinicians

Klaus Schnake ¹ , Julian Scherer ² , Gaston Camino-Willhuber ³ , Ulrich Spiegl ⁴ , Andrei Joaquim ⁵ , Harvinder Singh Chhabra ⁶ , Marcel F. Dvorak ⁷ , Gregory Schroeder ⁸ , Mohammad El-Sharkawi ⁹ , Richard Bransford ¹⁰ , Lorin Benneker ¹¹ , Sebastian Bigdon ^11,12

¹ Center for Spinal and Scoliosis Surgery, Erlangen, Germany,

² Division of Orthopaedic Surgery, Faculty of Health Sciences, University of Cape Town, Kapetown, South Africa,

³ Policina Gipuzkoa, San Sebastian, Spain,

⁴ Klinik für Unfallchirugie München Harlachingen, München, Germany,

⁵ Neurosurgery Division, Department of Neurology, State University of Campinas, Sao Paulo, Brazil,

⁶ Sri Balaji Action Medical Institute, New Delhi, India,

⁷ Combined Neurosurgical and Orthopedic Spine Program, Vancouver General Hospital, Vancouver, Canada,

⁸ Department of Orthopaedic Surgery, Rothman Institute, Thomas Jefferson University Hospital, Philadelphia, United States,

⁹ Department of Orthopaedic and Trauma Surgery, Faculty of Medicine, Assiut University, Assiut, Egypt,

¹⁰ Department of Orthopaedics and Sports Medicine, Harborview Medical Center, University of Washington, Seattle, United States,

¹¹ Department for Spine Surgery, Sonnenhof Spital, University of Bern, Bern, Switzerland,

¹² Department for orthopaedics and traumatology, Inselspital, University Hospital Bern, Bern, Switzerland

Background: Osteoporotic vertebral fractures are a significant global health concern, particularly affecting the aging population. A standardized classification system is essential for consistent diagnosis, treatment planning, and research. The AO Spine-DGOU Osteoporotic Fracture Classification System was developed to provide a comprehensive framework for these fractures. However, its reliability across diverse international settings has not been extensively validated. Objective: To evaluate the inter-rater reliability and intra-rater reproducibility of the AO Spine-DGOU Osteoporotic Fracture Classification System in a large, international, multicenter cohort of clinicians. Methods: A total of 320 clinicians from various regions, including Europe and Asia, participated in this study. Each participant assessed 27 osteoporotic vertebral fracture cases on two separate occasions, four weeks apart, to minimize recall bias. Assessments were conducted via an online platform, providing key images along with CT and MRI scans in sagittal, coronal, and axial views. Inter-rater reliability was measured using Fleiss' kappa coefficient (κ) to determine agreement among different raters. Intra-rater reproducibility was assessed by comparing each participant's classifications between the two assessments. Results: The overall agreement with the gold standard classification was 76% in both assessments. Inter-rater reliability demonstrated moderate agreement (κ = 0.57 in the first assessment and κ = 0.58 in the second assessment). Intra-rater reproducibility was substantial, with a mean κ of 0.66 and a median κ of 0.71. Higher agreement levels were observed for OF 4 and OF 5 fractures (substantial agreement), while OF 3 fractures exhibited lower agreement (moderate agreement). Conclusion: The AO Spine-DGOU Osteoporotic Fracture Classification System shows moderate to substantial reliability and reproducibility among clinicians internationally. These findings support its use as a standardized tool for classifying osteoporotic vertebral fractures, which can enhance global communication and inform clinical decision-making in spine care. Significance: This study represents the largest international validation of the AO Spine-DGOU classification to date, involving a diverse group of clinicians. The adoption of this classification system can improve consistency in the assessment and management of osteoporotic vertebral fractures worldwide, ultimately benefiting patient outcomes.

ID: 2409

A066: Craniocervical instability in Ehlers Danlos syndrome: a comparative analysis of radiological measurements and symptomatology

Dineth Fernando ¹ , Prashanth Rao ¹ , Ashish Diwan ²

¹ Brain and Spine Surgery, Neurosurgery, Norwest, Australia

² Spine Service, Orthopaedic Surgery, Kogarah, Australia

Introduction: Craniocervical instability (CCI) is a disabling consequence of ligamentous laxity at the craniocervical junction for some patients with Ehlers Danlos syndrome (EDS). This study investigates differences in the clinicoradiological presentation of EDS compared to non-EDS patients with suspected CCI and assesses the usefulness of dynamic imaging for the radiological evaluation of CCI. Material and Methods: This retrospective cohort study analyzed the medical records of a consecutive series of 104 patients referred to a single neurosurgeon (PR) between September 2019 and July 2024 with neurological symptoms clinically suggestive of CCI. Patients were divided into EDS and non-EDS groups. Symptoms at presentation were assessed using a CCI questionnaire. The modified clivo-axial angle (mCXA), Grabb-Mapstone-Oakes measurement (pB-C2), basion-axial interval (BAI) and basion-dental interval (BDI) were measured on T2W MRI in neutral, flexion, and extension. The angular displacement between C1 and C2 (C12-AD) was measured on axial CT images in maximal left and right rotation. Symptom prevalence and radiological measurements were compared between EDS and non-EDS groups. Frequencies of abnormal radiological measurements, as defined by established pathological thresholds, identified with multipositional imaging and neutral-only scans were compared. Intra- and inter-examiner reliability was assessed for the radiological measurements. The level of significance was set at α=0.019 after adjusting for multiple comparisons with a false discovery rate of 10%. Results: A total of 55 EDS and 49 non-EDS patients were included in this study. The EDS group had a 5.8 times greater female to male ratio in comparison to the non-EDS group (χ² = 11.497; Φ = 0.332; p = 0.001) and were 7.1 years younger on average (t = -3.524; Cohens d = -0.690; p = 0.001). EDS patients more commonly reported headache localized to the back of the head (p = 0.003), features of dysautonomia (palpitations, p = 0.015; syncope, p = 0.005; pre-syncope, p = 0.007; postural orthostatic tachycardia syndrome, p < 0.001; decreased gastrointestinal motility, p = 0.019; gastric reflux, p = 0.013; and frequent vomiting, p < 0.001), failure in school (p = 0.014), stabbing pain (p = 0.019), difficulty discerning temperature (p < 0.001), and problems with proprioception (p < 0.001). Median Modified Karnofsky score was lower in EDS patients (50 vs. 60, p = 0.002). EDS patients had more kyphotic mCXAs in neutral (134.33 ± 12.33° vs. 146.91 ± 11.03°; p < 0.001), flexion (130.50 ± 141.07° vs. 141.07 ± 9.48°; p < 0.001), and extension (154.18 ± 12.59° vs. 160.99 ± 10.60°; p = 0.004); larger pB-C2 in neutral (7.52 ± 1.40 vs. 6.85 ± 1.37; p = 0.015); and larger C12-AD in right (34.01 ± 4.65° vs. 29.17 ± 7.52°; p = 0.001) and left (34.49 ± 6.18° vs. 27.81 ± 6.98°; p < 0.001) rotation. Dynamic imaging was very strongly associated with increased detection of pathological mCXA (Φ = 0.633, p < 0.001), pB-C2 (Φ = 0.596, p < 0.001), and BDI (Φ = 0.341, p < 0.001) measurements, and strongly associated with increased detection of pathological BAI (Φ = 0.138, p < 0.001) measurements. Intra-examiner reliability for measurements was satisfactory (ICC > 0.700) for all measurements, but inter-examiner reliability was unsatisfactory for BAI and BDI. Conclusion: In patients with suspected CCI, those with EDS experience greater mechanical neuraxial deformity in the form of increased cervicomedullary angulation, ventral compression, and rotation at the C1-C2 motion segment. CCI in EDS patients has a distinct clinical presentation predominated by dysautonomia and multi-tract sensory changes. Dynamic imaging is useful in the radiological evaluation of suspected CCI, though adequate training in interpretation is required particularly in the identification of bony landmarks.

ID: 1804

A067: Comprehensive skeletal maturity index can obviate the need for hand radiographs for sanders scoring

Alison Dyszel ¹ , Elyette Lugo ¹ , Amit Jain ¹

¹ Johns Hopkins, Orthopaedic Surgery, Baltimore, United States

Introduction: Scoliosis radiographs are often used to assess both scoliosis curvature and skeletal maturity in pediatric patients. However, the Sanders score, extracted from hand radiographs, is considered the gold standard for assessing skeletal maturity and determining peak height velocity (PHV), which is not evaluated in scoliosis radiographs. On routine scoliosis radiographs, four growth indicators are often assessed: Risser staging, triradiate cartilage (TRC), proximal femur maturity index (PFMI), and proximal humerus ossification system (PHOS). This study investigates whether the incorporation of these four growth indicators into a comprehensive skeletal maturity index (RTFH), can reveal growth information as well as Sanders hand radiographs. Material and Methods: We retrospectively analyzed 205 radiographs of pediatric scoliosis patients from 2017 to 2024 who received both a scoliosis radiograph and a hand radiograph for bone age assessment on the same day. We graded each scoliosis radiograph based on four growth indicators: Risser, TRC, PFMI, and PHOS, using their individual grading scales. Risser was graded from 0 to 5; TRC from 0 (open) to 2 (closed); PFMI from 0 to 6; and PHOS from 1 to 5. These individual grades were added to create a comprehensive skeletal maturity index (RTFH), with scores ranging from 2 to 18. The RTFH was then compared to the Sanders score extracted from the hand radiograph. An RTFH score of < 6 was indicative of pre-PHV, correlating with a Sanders score of < 3; an RTFH score of 6-10 indicated a patient at PHV, correlating with a Sanders score of 3-4; and an RTFH score of > 10 indicated post-PHV, correlating with a Sanders score of > 4. A matching RTFH and Sanders score would indicate that evaluating the combination of Risser, TRC, PFMI, and PHOS is adequate for determining PHV compared to the gold standard. Results: Among the 205 radiographs analyzed, 96.10% of the RTFH scores precisely correlated with the Sanders scores. Specifically, 83% of these scores accurately indicated pre-PHV, with an RTFH of less than 6 corresponding to a Sanders score of less than 3. Additionally, 100% of the scores effectively identified PHV, with an RTFH ranging from 6 to 10 correlating with a Sanders score of 3 to 4. Furthermore, 95.4% of the scores correctly identified post-PHV, with an RTFH greater than 10 corresponding to a Sanders score of greater than 4. Among the 3.90% of scores that did not match, the RTFH overestimated the patient’s skeletal maturity in 6 patients and underestimated in 2 patients in comparison to the Sanders score. Conclusion: There is a significant correlation between the use of our comprehensive skeletal maturity index (RTFH) and the gold standard Sanders score. This indicates that RTFH could be a viable method for evaluating PHV in patients with scoliosis, and obviate the need for extra radiation from hand radiographs.

ID: 1149

A068: Deep learning model for lumbar spinal stenosis on MRI: comparison with general radiologists and orthopedists

You Jun Lee ¹ , Changshuo Liu ² , Jiong Hao Tan ³ , Yong Han Ting ¹ , Alex Quok An Teo ³ , Andrew Makmur ¹ , Zongchen Li ¹ , Alvin Hong Zhi Ng ⁴ , Aric Lee ¹ , Chongyan Wang ³ , Xinyi Lim ³ , Qai Ven Yap ⁵ , Joey Chan Yiing Beh ⁴ , Shuxun Lin ⁶ , Naresh Kumar ³ , Beng Chin Ooi ² , James Hallinan ¹

¹ National University Hospital, Department of Diagnostic Imaging, Singapore, Singapore,

² National University of Singapore, Department of Computer Science, School of Computing, Singapore, Singapore,

³ National University Health System, University Spine Centre, University Orthopaedics, Hand and Reconstructive Microsurgery (UOHC), Singapore, Singapore,

⁴ Ng Teng Fong General Hospital, Department of Radiology, Singapore, Singapore,

⁵ National University of Singapore, Biostatistics Unit, Yong Loo Lin School of Medicine, Singapore, Singapore,

⁶ Ng Teng Fong General Hospital, Division of Spine Surgery, Department of Orthopaedic Surgery, Singapore, Singapore

Introduction: Deep learning (DL) models can aid radiologists in interpreting lumbar spinal stenosis (LSS). Convolutional neural network (CNN) and transformer models have been used in image classification tasks, the latter showing potential improved performance with increased complexity. This study aims to develop and optimize CNN and transformer models for region of interest (ROI) detection and LSS severity classification on MRI, and compare their performance to general radiologists, orthopedists, and specialists-in-training using internal and external datasets to assess generalizability. Material and Methods: Lumbar spine MRI studies from Sep-2015 to Sep-2019 were retrospectively obtained. Exclusion criteria were spinal instrumentation, suboptimal image quality, post-gadolinium studies, and severe scoliosis. Axial T2-weighted and sagittal T1-weighted images were used. Internal datasets were split into training (74%), validation (8%) and test (18%) sets. A local external test set of 100 studies was available. Labelling was performed using LabelImg (https://github.com/tzutalin/labelImg). Training data were labelled by 4 radiologists using predefined gradings (normal/mild/moderate/severe) for the central canal, lateral recesses and neural foramina. Two models, a 2-component model using CNN for ROI detection and classification, and a transformer model utilizing a CNN to extract latent features first and a transformer architecture for ROI detection and classification, were developed. Consensus labelling by two experienced musculoskeletal radiologists served as the reference standard. Test sets were labelled by 8 participants (2 general radiologists, 2 radiologists-in-training, 2 orthopedists, 2 orthopedists-in-training). Detection recall (%), interrater agreement (Gwet κ), sensitivity, and specificity were evaluated. Results: Overall, 564 MRI lumbar spine studies were included (mean age = 52 ± 19 [SD]; 302 women), with 464 used for training (74%) and validation (8%), and 100 for the internal test set (18%). Both models showed high recall for all regions of interest (> 94%), similar to the participants. Quaternary classification (normal/mild/moderate/severe) by the CNN model, transformer model, and participants showed respective kappas for central canal 0.96/0.89/0.79-0.87, lateral recesses 0.92/0.77/0.54-0.77, and neural foramina 0.96/0.82/0.65-0.74 on internal testing (p < 0.001); for central canal 0.94/0.83/0.64-0.80, lateral recess 0.86/0.69/0.31-0.65, and neural foramina 0.95/0.79/0.60-0.77 on external testing (p < 0.001). Dichotomous classification (normal/mild vs. moderate/severe) by the CNN model, transformer model, and participants showed respective kappas for central canal 0.99/0.99/0.97-0.98, lateral recesses 0.98/0.94/0.81-0.94, and neural foramina 0.98/0.95/0.91-0.95 on internal testing (p < 0.001); for central canal 0.99/0.97/0.92-0.97, lateral recess 0.97/0.90/0.61-0.91, and neural foramina 0.99/0.94/0.87-0.93 on external testing (p < 0.001). Conclusion: The CNN and transformer models showed high agreement with the reference standard for LSS classification, with the CNN model significantly outperforming the transformer model for all regions of interest on both internal and external testing. The CNN model overall also showed higher or similar sensitivity and specificity compared to the transformer model. Compared to a range of clinicians, the CNN model showed superior performance and the transformer model showed similar to superior performance for classification of central canal, lateral recess and neural foraminal stenosis. Study limitations include bias from the limited number of participants and expert radiologists performing consensus labelling. Performance difference between the CNN and transformer models requires further investigation. Overall, these models could assist clinicians in report generation, surgical planning and patient education.

ID: 2554

A069: Predictors of pelvic incidence discrepancy in EOS imaging and lumbar spine/pelvic computed tomography

Maile Curbo ¹ , Rebekah Julie Park ¹ , Srivathsan Ramesh ¹ , Jacob Siahaan ¹ , James Showery ¹

¹ The University of Texas Health Science Center at Houston, Department of Orthopedics, Houston, United States

Introduction: Although PI is considered a constant pelvic parameter, exaggerated motion through the sacroiliac joints (SIJ) may result in variation according to posture. As EOS imaging becomes more common in surgical planning, understanding these discrepancies is crucial. The purpose of the study was to identify predictors of discrepancies in pelvic incidence (PI) measurements between EOS and computed tomography (CT) imaging. Material and Methods: A single-center retrospective review was conducted on patients who underwent both EOS full spine standing imaging and lumbar spine/pelvic CT within 12 months between July 1, 2022, and January 15, 2024. Demographic and medical history data were collected. PI was measured from EOS images using Surgimap and from CT via 3D reconstructions created with Mimics and 3-Matic. Results: For 32 patients, Bland-Altman analysis showed a mean bias of 1.7° (95% CI: 0.460–2.93) with limits of agreement -5.02° to 8.41°. Multivariable linear regression found levels of lumbar fusion (β = 1.4, CI: 0.7-2, p < 0.001) and reported hip pain (β = -3.1, CI: -5.8 to -3.2, p = 0.030) to be significant predictors of PI discrepancy. The intraclass correlation coefficients for consistency and agreement (96.0% and 95.9%, respectively) were excellent, with a significant discrepancy observed in patients who had previously undergone hip replacements. Conclusion: Although PI is considered a constant pelvic parameter, exaggerated motion through the sacroiliac joints based on variations in posture may contribute to discrepancies between EOS and CT measurements. Our findings challenge the assumption of PI as a fixed value and suggest that surgical planning must account for potential variation due to various biomechanical and imaging-related factors, including compensatory movement in adjacent joints and obscuration of the femoral heads. As EOS imaging becomes more common in surgical planning due to reduced radiation exposure and time efficiency, understanding these discrepancies is crucial. Lumbar fusion and hip pathology significantly affect the measurement of PI between EOS and CT which may contribute to suboptimal surgical planning and execution.

ID: 985

A070: Sagittal spinopelvic parameters in healthy Chinese children: a retrospective analysis of 1,098 cases

Ziming Yao ¹ , Jiahao Jiao ¹ , Dong Guo ¹

¹ Beijing Children’s Hospital, Department of Orthopaedics, Beijing, China

Introduction: The reconstruction of sagittal alignment has become a critical focus in the treatment of spinal deformities. While normative spino-pelvic parameters and their relationships have been extensively studied in adults, the normal sagittal parameters in children and their developmental changes remain unclear. The aim of this study was to describe the parameters of the normative spino-pelvic parameters in children and to analyze their changes during growth and development. Material and Methods: We retrospectively analyzed data from 1,098 healthy children who underwent standing full-spine radiographs at our hospital. Radiographic measurements included thoracic kyphosis (TK), lumbar lordosis (LL), pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), and Dubousset’s lumbosacral angle (Dub-LSA). TK was categorized into TK_(T1-T14) and TK_(T4-T12), while LL was divided into LL_(L1-L4) and LL_(L4-S1). Patients were grouped based on age, Risser stage, and triradiate cartilage status. Sagittal spino-pelvic parameters were compared across groups using one-way ANOVA with Bonferroni correction for post hoc analysis, and sex-based differences within each group were evaluated using t-tests or rank-sum tests. Results: Of the 1,098 children (634 males, 464 females; mean age: 9.7 years), 264 were in Group 1 (mean age: 6 years), 249 in Group 2 (mean age: 9 years), 258 in Group 3 (mean age: 11 years), 168 in Group 4 (mean age: 12 years), and 159 in Group 5 (mean age: 14 years). Analysis revealed that with growth, PI increased from 37.2° to 43.4° (p < 0.001), PT increased from 4.4° to 9.7° (p < 0.001), and SS remained unchanged (p = 0.134). LL increased from 48.4° to 51.6° (p = 0.002), primarily driven by an increase in LL_(L1-L4) (from 14.9° to 17.5°). No significant differences were observed in TK or Dub-LSA across the groups. Post hoc analysis indicated that the most pronounced changes in PI, PT, LL, and LL_(L1-L4) occurred between the ages of 11 and 12 years. Conclusion: This study is the first large-sample, single-center analysis of sagittal parameters in healthy children from China. PI and LL increased gradually during growth, peaking between 11 and 12 years of age. PT increased consistently with PI during growth, while SS remained relatively unchanged. The increase in LL was primarily attributed to the rise in proximal LL.

ID: 1664

A071: Evaluation of psoas muscle atrophy following lateral lumbar interbody fusion: a retrospective MRI analysis

Daniel Rusu ¹ , William Karakash ¹ , Kevin Sun ¹ , Henry Avetisian ¹ , Jeffrey C. Wang ¹ , Raymond Hah ¹ , R. Kiran Alluri ¹

¹ Keck School of Medicine of USC, Los Angeles, United States

Introduction: Lateral lumbar interbody fusion (LLIF) is a minimally invasive surgical technique used for disc height restoration, deformity correction, and indirect spinal decompression. This retroperitoneal approach involves psoas muscle dissection. LLIF has gained popularity in surgery due to its reduced tissue trauma, decreased intraoperative blood loss, and preservation of the posterior spinal ligamentous structures. However, postoperative complications frequently include transient hip flexor weakness and sensory disturbances in the proximal thigh. Although extensive research addresses lumbar plexus neuropraxia related to LLIF, there is limited investigation into the effects of this approach on psoas muscle integrity. This study aims to compare preoperative and postoperative psoas muscle parameters to assess potential iatrogenic atrophy following LLIF. Materials and Methods: This retrospective review examined patients who underwent LLIF at a single tertiary academic hospital from 2014-2024. Patients were included if they had both a preoperative MRI and postoperative MRI > 3 months after surgery. Exclusion criteria included deformity, infection, and malignancy. Bilateral psoas atrophy was assessed by comparing preoperative and postoperative MRI parameters: cross-sectional area (CSA), anteroposterior (AP) and mediolateral (ML) diameters, and Goutallier classification of fatty infiltration. Welch's two-sample t-test was used to compare differences between the surgical approach side and the contralateral side, evaluating potential iatrogenic psoas muscle atrophy following LLIF procedures. Results: A total of 43 patients met inclusion, with a median follow-up period of 19 months. Comparative analysis between the surgical approach side and the contralateral side revealed no statistically significant differences in several key parameters. The percent change in cross-sectional area (CSA) was -8.8% [-43.3%, 25.6%] for the surgical side versus -0.96% [-55.8%, 53.8%] for the contralateral side (p = 0.115). Similarly, the percent change in mediolateral (ML) diameter showed no significant difference: -8.0% [-41.7%, 25.7%] for the surgical side compared to -2.8% [-36.2%, 30.5%] for the contralateral side (p = 0.155). The absolute change in Goutallier classification was also not statistically significant: 0.19 [-0.71, 1.09] for the surgical side versus 0.09 [-0.76, 0.95] for the contralateral side (p = 0.328). However, the percent change in anteroposterior (AP) diameter showed a trend towards statistical significance: -3.86% [-26.5%, 18.7%] for the surgical side versus 0.32% [-20.9%, 21.5%] for the contralateral side (p = 0.081). Conclusions: This retrospective analysis of patients undergoing LLIF reveals no statistically significant evidence of iatrogenic psoas muscle atrophy associated with the surgical approach. However, the trend towards significance in the anteroposterior diameter suggests a need for further investigation. These findings imply that LLIF may not result in substantial long-term psoas muscle atrophy, which could explain the transient nature of postoperative hip flexor weakness. Future prospective studies with larger sample sizes and extended follow-up periods are recommended to confirm these results and further elucidate the long-term effects of LLIF on psoas muscle integrity.

ID: 1084

A072: Comparative analysis of endplate vBMD and EBQ for predicting cage subsidence in lateral lumbar interbody fusion

Hanming Bian ^1,2 , Qiang Yang ²

¹ Tianjin Medical University, Tianjin, China,

² Tianjin University, Tianjin Hospital, Tianjin, China

Objective: To compare the predictive efficacy of QCT-based endplate volumetric bone mineral density (EP-vBMD) and MRI-based endplate VBQ score (EBQ) for cage subsidence after lateral lumbar interbody fusion (LLIF) combined with posterior pedicle screw fixation (PSF). Method: A series of 97 patients underwent single level LLIF in conjunction with PSF in our institution between January 2019 to April 2023 were included in the present retrospective study. We measured the EP-vBMD based on the preoperative CT using the Phantom-less QCT software. Measurement of the EBQ score was based on preoperative MRI. CS was defined as a decrease of more than 2mm in the midpoint height of the intervertebral space. The predictive efficacy of EP-vBMD and EBQ for CS was compared by comparing the area under the receiver operating characteristic (ROC) curve (AUC). Result: A total of 97 patients who underwent LLIF were included in this study, including 31 patients with CS and 66 patients without CS. The EP-vBMD of the CS group was lower than that of the non-subsidence group (NCS), and EBQ was higher than that of the NCS group. The area under the ROC curve of EP-vBMD for predicting CS was larger than that of global and segmental vBMD. The area under the ROC curve of EBQ for predicting CS was larger than that of global and segmental VBQ, and the AUC of EP-vBMD was larger than that of EBQ. Finally, the combination of EP-vBMD and EBQ had the largest area under the ROC curve. Conclusion: The regional endplate BMD assessment based on QCT and MRI can effectively predict cage subsidence after LLIF, and it has better predictive efficiency than the global or surgical segmental cancellous bone BMD assessment results.The multimodal prediction method combining EP-vBMD and EBQ has better prediction efficiency than single modality.

Keywords: cage subsidence; endplate; Phantom-less QCT; MRI; Volumetric bone mineral density; VBQs.

OP09: Biomechanics

ID: 2186

A073: Validation of the RWD precise impactor for a rodent cervical spinal cord injury contusion model

Jose Castillo ¹ , Michael Le ¹ , Christopher Privetti ² , Richard Price ¹ , Allan Martin ¹ , Kee Kim ¹ , Aijun Wang ²

¹ UC Davis Medical Center, Sacramento, United States,

² UC Davis, Sacramento, United States

Background: Cervical spinal cord injuries are the most common human spinal cord injury (SCI). Various contusion models have been developed to mirror SCI pathology in humans but few have described cervical-level injuries. We utilized the RWD Precise Impactor which uses penetration depths and a controlled dwell time to generate three severities of cervical spinal cord contusion. The goal of this study is to determine an optimal penetration depth that produces a consistent and reliable graded SCI for testing potential new therapeutic modalities. Methods: Hemi-contusion SCI was created with the RWD precise impactor on 14 rats, with 3 as uninjured controls. Penetration depths of 2.11 mm (n = 4), 2.24 mm (n = 4), and 2.36 mm (n = 3) were used to create mild, moderate, and severe injuries. Behavioral assessments on weeks 1, 2, 5, and 8 included a grooming test, forelimb asymmetry test, and the Irvine, Beatties and Bresnahan forelimb scale (IBB). After 8 weeks rats were euthanized and spinal cord histology was performed. Results: The three different penetration depth groups were consistent in their motor function outcomes and relative recovery. Deficits in motor function were graded, with a significant difference between the mean IBB scores per injured group at week 8 (p < 0.0001). The 2.11 mm penetration depth animals recovered to near normal motor function and did not have significantly less white matter when compared to normal controls. In the mild (2.11 mm) and moderate (2.24 mm) groups there was significant improvement in the amount of ipsilateral forelimb usage throughout the study period, while the severe (2.36 mm) group remained with 100% asymmetrical usage. Conclusions: Using the RWD Precise Impactor we were able to create a reproducible model of cervical SCI with severity of injury correlating with greater penetration depth. A penetration depth of 2.24 mm appears to provide enough capacity to allow for differences to be seen with various treatment arms in future studies.

ID: 1203

A074: Not all are created equal: lumbosacral anatomy is different in pediatric spondylolysis

Ryan Finkel ¹ , Nakul Narendran ¹ , Daniel Farivar ¹ , Paal Nilssen ¹ , Melodie Metzger ¹ , David Skaggs ¹ , Kenneth Illingworth ¹

¹ Cedars-Sinai Medical Center, Department of Spine Surgery, Los Angeles, United States

Introduction: Pediatric spondylolysis is a known source of low back pain. With its low incidence, there lacks data describing how geometric parameters of the lumbosacral anatomy contribute to its development. This study compares novel parameters on computed tomography (CT) scans of pediatric patients with and without spondylolysis at L5. Materials and Methods: CT-scans of pediatric patients at a single-center (2005-2022) were reviewed. Patients with isolated L5 spondylolysis were identified and matched 1:4 (age, sex, BMI) to patients without spondylolysis. Sagittal parameters were assessed: sacral slope angle, sacral table angle, L4-S1 and L5-S1 Cobb angles, the horizontal angle of the L5 pars interarticularis, and the distances between the L4 inferior articular process (IAP) and the S1 superior articular process (SAP) and their respective individual distances to the L5 pars. On coronal view, the percent subluxation of L4 IAP below the facet joint was assessed. Statistical analyses included two-tailed t-tests for each parameter and Pearson correlation analysis with significance at 0.05. Results: The incidence of L5 spondylolysis was 3% (32/1084). Spondylolysis patients (mean age 15 ± 2.3, 46.9% female) were compared to 122 patients without spondylolysis. The horizontal angle of the L5 pars was greater in spondylolysis patients (142.5 ± 10.2 vs. 119.9 ± 5.9, p < .001). There was less distance (mm) between L4 IAP and S1 SAP (11.3 ± 3.9 vs. 14.7 ± 2.9, p < .001) in the spondylolysis group. There was less distance (mm) from both L4 IAP (2.6 ± 1.7 vs. 5.4 ± 2.2, p < .001) and S1 SAP (0.7 ± 0.4 vs. 1.5 ± 0.7, p < .001), respectively, to the L5 pars. Spondylolysis patients had greater subluxation of L4 IAP beneath the facet joint (29.0 ± 20.1 vs. 13.2 ± 11.4, p < .001). There was no difference in sacral slope, sacral table, or Cobb angles. Pearson’s analyses revealed that a larger horizontal angle of the L5 pars is strongly associated with spondylolysis (0.59). Conclusion: Pediatric patients with L5 spondylolysis are more likely to have a horizontal L5 pars situated closer to both the L4 IAP and S1 SAP, therefore causing increased impingement on lumbar extension.

ID: 324

A075: Preoperative disc degeneration and age predict changes in adjacent segment kinematics three years after anterior cervical discectomy and fusion

Kimberly Hua ¹ , Clarissa LeVasseur ^2,3 , Samuel Pitcairn ² , Romano Sebastiani ¹ , Christopher Como ² , Shelley Olivera Barbosa ² , Jeremy D. Shaw ² , Joon Y. Lee ^2,3 , William F. Donaldson ² , William Anderst ²

¹ University of Pittsburgh School of Medicine, Pittsburgh, United States,

² University of Pittsburgh, Department of Orthopaedic Surgery, Pittsburgh, United States,

³ Bethel Musculoskeletal Research Center, Pittsburgh, United States

Introduction: Anterior cervical discectomy and fusion (ACDF) remains the most common surgical treatment for cervical radiculopathy and myelopathy [1]. Within 10 years of ACDF, approximately 25% of patients develop adjacent segment disease (ASD) and require reoperation [2]. The etiology of ASD is unclear but proposed to be related to increased stress in discs adjacent to fused segments and/or genetic predisposition to disc degeneration [3,4]. Previous studies suggest preoperative disc degeneration has the strongest association with ASD [5]. Vertebral kinematics can be used to infer disc loading. The purpose of this study was to identify patient factors that predict changes in adjacent segment kinematics three years after ACDF. We hypothesized that preoperative disc height and disc bulge, which characterize preoperative disc degeneration, would be the primary predictors of changes in adjacent segment range of motion three years after ACDF. Materials and Methods: Patients who were scheduled to receive ACDF performed three trials each of full range of motion (ROM) flexion-extension and axial rotation while synchronized biplane radiographs were collected at 30 images/sec before and three years after ACDF. Preoperative CT scans of the cervical spine were used to create subject-specific 3D bone models. Digitally reconstructed radiographs were generated from the 3D bone models [6] and matched to the biplane radiographs using a validated volumetric model-based tracking technique [7]. Joint kinematics, ROM at each motion segment, and disc height were calculated [8]. Patient age, sex, BMI, smoking status, diabetes, psychiatric history, inciting events, length of symptoms, and disc bulge were collected. Multiple linear regression was performed to identify patient factors that predicted changes in adjacent segment kinematics. Results: Sixty-three patients (22M, 28F, mean age: 47.8 ± 8.7 years) completed preoperative and postoperative testing. From before to three years after ACDF, flexion/extension ROM increased by 1.2 ± 3.1° (range -9.7° to 9.1°) at the superior adjacent motion segment and by 2.4 ± 3.9° (range -6.2° to 10.1°) at the inferior adjacent motion segment. Axial rotation ROM increased by 0.6 ± 2.5° (range -4.5° to 6.6°) at the superior adjacent motion segment and by 1.0 ± 2.9° (range -4.0° to 8.4°) at the inferior adjacent motion segment. Greater BMI (β = -0.194; p = 0.021) and age (β = -0.136; p = 0.027) predicted decreased superior adjacent segment flexion/extension ROM after ACDF. Younger age (β = -0.082; p = 0.078) and greater preoperative superior adjacent segment disc height (β = 1.040; p = 0.052) predicted increased superior adjacent segment rotation ROM after ACDF. Younger age (β = -0.231; p = 0.016) predicted increased flexion/extension ROM after ACDF. Conclusions: The results partially supported our hypothesis. Preoperative disc degeneration, characterized by disc height only, predicted increases in superior adjacent segment ROM after ACDF. Age predicted changes in superior and inferior adjacent segment ROM after ACDF. Surgeons may be able to use patient-specific information to develop a more accurate prognosis for patients receiving ACDF.

References

1. Saifi et al., Spine J, 2018.

2. Hilibrand et al., JBJS Am, 1999.

3. Matsunaga et al., Spine, 1999.

4. Battie et al., Spine, 2009.

5. Simpson et al., Spine, 2008.

6. Treece et al., Comput Graph, 1999.

7. Anderst et al., Spine, 2011.

8. Anderst et al., Med Eng Phys, 2017.

ID: 416

A076: Improved axial stability associated with bilateral compared to ipsilateral pedicle screw fixation in transforaminal lumbar interbody fusion (TLIF): an in-vitro human cadaveric spondylolysis model

Layla Dawit ¹ , Theodore Joaquin ² , Jonathan Day ² , Daina Brooks ³ , Zan Naseer ³ , Mesfin Lemma ³ , Bryan Cunningham ³

¹ Harvard University, Cambridge, MA, United States,

² Georgetown University School of Medicine, Washington, DC, United States,

³ MedStar Union Memorial Hospital, Baltimore, MD, United States

Introduction: Minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) utilizing unilateral fixation has gained popularity in recent years for the treatment of a host of common spinal conditions, including lumbar spondylolisthesis, a condition characterized by vertebral instability and malalignment. Although MIS TLIF with unilateral pedicle screws remains a common and successful form of treatment for symptomatic degenerative spondylolisthesis, this procedure remains controversial in the setting of isthmic spondylolisthesis, where the spine is inherently more unstable by virtue of defects in the pars interarticularis. Recent studies have demonstrated increased post-surgical cage migration, pain, and lower fusion rates with the use of UPS for the isthmic subtype. The purpose of this study was to quantify changes in multidirectional stability of the lumbar spine via biomechanical and radiographic evaluation following TLIF augmented with unilateral vs bilateral pedicle screws in the setting of pars defects. To our knowledge, this has not yet been reported in the literature. This study may assist surgeons in formulating optimal treatment plans for this subgroup of patients presenting with spine-related pain and disability. Material and Methods: Eleven lumbosacral specimens were used in this investigation. Five InfraRed Emitting Diodes (IRED) motion detection markers were placed on the top/base containers and intervening vertebral bodies (L3, L4 and L5), equipped with three non-co-linear infrared emitting diodes designed for detection by an optoelectronic motion analysis system. Reconstructions at the operative L4-L5 level were performed and motions quantified for seven treatment conditions. Multidirectional flexibility testing was performed utilizing a custom-designed, six-degree-of freedom spine simulator. The lumbosacral specimens were evaluated under six sequential loading conditions including: flexion-extension, lateral bending and axial rotation using an unconstrained, pure moment system at an angular displacement rate of 3 degrees/second. Results: BPS fixation significantly reduced segmental range of motion compared to UPS in the intact setting and the setting of bilateral pars defects for flexion-extension (FE), lateral bending (LB), and axial rotation. There was no statistically significant difference when comparing TLIF with UPS vs BPS in the setting of pars defects for either FE (p = 0.0618) or LB (p = 0.0642). However, the ROM in axial rotation for the TLIF cage + BPS (72.64 ± 39.36%) in the setting of pars defects demonstrated significantly increased stability (p = 0.0029) at the operative level compared to the TLIF cage + UPS (110.96 ± 47.49%), with a mean difference of 1.723° (0.5582-2.887, p = 0.001). Conclusion: Our findings indicate TLIF with bilateral fixation provides significantly greater spinal stability in axial rotation than unilateral fixation alone in the setting of pars/isthmic defects. In the clinical setting, this may be accomplished via traditional unilateral MIS TLIF, but with the addition of percutaneous pedicle screw fixation on the contralateral side via robotic or navigation technologies, now widely available at most hospitals. This would preserve the minimally invasive nature of the procedure while improving stability across the construct. We hypothesize that the improved stability afforded by the bilateral fixation would help mitigate several unilateral MIS-TLIF concerns when treating patients with isthmic spondylolisthesis reported in the literature, including cage migration and reduced fusion rates.

ID: 1174

A077: The impact of sacral slope on joint kinematics and facet loading in L5-S1 disc replacement

Suhas Etigunta ¹ , Christopher Mikhail ¹ , Andy Liu ¹ , Sang Kim ¹ , Melodie Metzger ¹

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

Introduction: Total disc replacement (TDR) is increasingly utilized for the treatment of lumbar degenerative disc disease (DDD) in cases where conservative treatment fails. Despite its popularity, lumbar TDR - particularly at the lumbosacral junction (L5-S1) - has not seen the same widespread adoption as cervical TDR. This may be due to the unique biomechanical challenges posed by the lumbosacral junction, which is influenced by sacral slope and related forces. The lumbosacral junction is subject to higher shear forces due to its inclination, and the effect of varying sacral slopes on the biomechanical performance of TDR at this level has not been thoroughly investigated. This study aims to explore the impact of sacral slope on anterior translation and facet joint pressures at L5-S1 following TDR. This biomechanical study investigates the impact of sacral slope on anterior translation and facet pressures in the lumbosacral spine following TDR at L5-S1. Materials and Methods: Seven fresh-frozen human lumbosacral (L5-S1) cadaveric segments were obtained and biomechanically tested. Each specimen was prepared and tested under varying sacral slopes, ranging from 20° to 70° in 10° increments, using a custom-built apparatus. This apparatus applied combined compressive and shear forces while thin pressure sensors (Tekscan) were inserted into the facet joint capsules to measure facet pressures. Specimens were tested first in their intact state and then after implantation of a Pro-disc-L (Synthes Spine) prosthetic disc. Anterior translation of the disc and facet pressures were measured at each sacral slope, allowing comparison between intact and post-TDR states. Results: In both the intact and post-TDR states, anterior translation increased as sacral slope increased, with the highest translation observed at 70°. Notably, the percent change in anterior translation following TDR implantation showed an inverse relationship with sacral slope. At a sacral slope of 50°, anterior translation approached near-intact levels, indicating that the implant resisted anterior translation more effectively at higher sacral slopes. Facet pressures, while increasing with sacral slope, exhibited a general decreasing trend in percent change after TDR, though these changes were not statistically significant. The highest facet pressures were observed at lower sacral slopes in both intact and TDR specimens, suggesting that higher sacral slopes may redistribute forces away from the facets and toward the TDR implant. Conclusion: This study demonstrates that increasing sacral slope leads to higher anterior translation and facet pressures at the lumbosacral junction in both intact and post-TDR conditions. Interestingly, the inverse relationship between sacral slopes may promote a biomechanical environment in which shear forces are transferred from the facets to the TDR implant. This biomechanical shift may place the implant in an extended position, reducing facet load but potentially increasing implant wear. These findings underscore the importance of considering sacral slope when planning TDR at L5-S1, as higher sacral angles may influence implant function, longevity, and long-term outcomes. Further studies are necessary to evaluate the clinical implications of these biomechanical changes, particularly in relation to implant wear and failure rates over time. Given the increasing use of TDR, understanding the role of sacral slope could improve patient selection and optimize surgical outcomes, especially for patients with significant sacral inclination.

ID: 748

A078: Lumbar disc height variation in health individuals

Emily Mills ¹ , Jane Han ¹ , McKenzie Culler ¹ , Mary Richardson ¹ , Brian Chung ¹ , Jennifer Wang ¹ , Nathaneal Heckmann ¹

¹ Keck School of Medicine at the University of Southern California, Los Angeles, United States

Introduction: Prior studies have reported the average lumbar disc heights, with most studies concluding that the L4-5 disc is tallest in all individuals; however, no studies have examined if there exists a variation in disc heights between individuals. The purpose of this study was to examine the individual variation in disc heights between lumbar levels. Material and Methods: Standing lateral lumbar spine radiographs of 50 healthy young subjects (25 male, 25 females) between the ages of 18 to 35 years old were analyzed. Those with a history of hip or spinal pathologies and hip or spinal surgeries were excluded. Anterior (Ha) and posterior (Hp) disc heights as well as superior (Ds) and inferior disc depths (Di) were measured from L1/L2 to L5/S1. Disc height index (DHI) was quantified utilizing an adaptation of Farfan’s method: [(Ha+Hp)/(Ds+Di)]x100. Results: Subjects had an average age of 25.7 ± 2.3 years and BMI of 24.1 ± 3.0 kg/m². Ha was tallest at L5-S1 (n = 29), followed by L4-5 (n = 17), followed by L3-4 and L2-3 (both n = 2). Hp had more variation, with L4-5 being the tallest in 18 volunteers, followed by L5-S1 (n = 11), L3-4 (n = 9), L2-3 (n = 6), and L1-2 (n = 6). In most individuals, L5-S1 DHI was the tallest (n = 30) followed by L4-5 (n = 19) and L3-4 (n = 1). Conclusion: The individual variations of disc height throughout the lumbar spine has not been previously reported. The present data suggests that there is variation in disc height between individuals and not all subjects have the greatest contribution from L4-L5. The majority of subjects had the largest DHI and Ha at L5-S1. Hp had more variation and was tallest at L4-5 in most individuals. This data gives further insight into lateral lumbar radiographs and natural disc height variation.

ID: 1925

A079: Does the lumbar spine change shape after just a decompression-only surgery? An analysis of the segmental and adjacent levels

Jack Sedwick ^1,2 , Aiyush Bansal ² , Takeshi Fujii ^2,3 , Maxey Cherel ¹ , Laura Reynolds ^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: Lumbar spinal stenosis (LSS) often results in a loss of lumbar lordosis due to chronic forward leaning. Lumbar decompression surgery, which involves the removal of sections of the lamina, ligamentum flavum, and osteophytes, is commonly performed to relieve symptomatic LSS. While decompression surgery is known to preserve lumbar spine mobility, its impact on adjacent segmental and disc angles, especially without fusion, is less understood. This study investigates changes in sagittal alignment at adjacent segments following decompression surgery for LSS. Materials and Methods: This retrospective study included 31 patients who underwent isolated L4-L5 laminectomies, discectomies, or both between 2015 and 2024, with preoperative imaging within a year before surgery and postoperative imaging within six months. Patients with prior spine surgeries were excluded. Preoperative and postoperative segmental and disc angles at L1-L2, L2-L3, L3-L4, L4-L5, and L5-S1 were measured using weight-bearing lateral radiographs. Lumbar lordosis (LL) was measured from the superior endplate of L1 to the superior endplate of S1. Univariate and multivariate linear analyses were conducted to predict changes in adjacent disc and segmental angles at L3-L4 (cranial) and L5-S1 (caudal), with predictors including age, sex, BMI, surgical approach (MIS or open), type of procedure, preoperative LL, and changes at the L4-L5 level. Results: The study cohort included 31 patients, with 17 females and 14 males, all of whom had surgeries at L4-L5. Among them, 23 underwent laminectomies and 8 had combined laminectomy and discectomy procedures. The analysis revealed that preoperative lumbar lordosis significantly influenced changes at L5-S1. Greater preoperative LL was associated with a decrease in both disc angle (β = -0.27, p = 0.01) and segmental angle (β = -0.25, p = 0.003) at L5-S1. Additionally, changes in the segmental angle at L4-5 were significantly associated with changes in the disc angle at L5-S1 (β = 0.73, p = 0.001). No significant predictors were found for changes at L3-L4. Conclusion: This study demonstrates that lumbar decompression surgery, even without fusion, can lead to changes in adjacent segmental and disc angles, particularly at L5-S1. Greater preoperative lumbar lordosis was associated with reduced lordosis at L5-S1 postoperatively. While the biomechanical changes observed post-decompression are less pronounced than those seen with fusion, these findings suggest that isolated decompression can still influence adjacent segment alignment. Further research is needed to explore the long-term clinical implications of these changes and their impact on patient outcomes.

Keywords: Lumbar Decompression Surgery, Sagittal Alignment, Adjacent Segment Disease, Lumbar Lordosis, Segmental Angle, Spinal Stenosis

ID: 2023

A080: Influence of trunk muscle activity on spinal geometric compensation: a cross-sectional case-controlled investigation

Adi Mithani ¹ , Ahmed Aoude ² , Mark Driscoll ³

¹ McGill University, Biomedical Engineering, Montreal, Canada,

² McGill University Health Center, Surgery, Montreal, Canada,

³ McGill University, Mechanical Engineering, Montreal, Canada

Introduction: Trunk muscle activation disturbances may trigger adaptations in spinal geometry. The flexion relaxation phenomenon (FRP) is defined as the reduction in electrical activity of the erector spinae muscles during forward bending. However, low back pain (LBP) subjects exhibit elevated paraspinal muscle activity in forward bending. In-vivo analyses have shown that increases in paraspinal muscle activity has been associated with reduced lumbar range of motion. However, data concerning the geometric compensatory response of the spine, to changes in muscle activity, have yet to be explored. This in vivo study investigates how LBP-related changes in trunk muscle activation affect spinal geometry, specifically lumbar L2-S1 IVR, lumbar lordosis (LLA), thoracic kyphosis (TKA), lumbar range of motion (RoM), and abdominal muscle activity during a 60° passive forward bending maneuver. Material and Methods: A case-controlled study included fifteen LBP and 18 asymptomatic participants. Participants performed a guided 60° flexion in a motion bucky apparatus with a fixed pelvis. X-ray fluoroscopy captured L2-S1 IVR and surface EMG (sEMG) measured activity from multifidus (MF), iliocostalis (ILM), longissimus (LGM), gluteus (GM), rectus (RA) and external oblique (EOM) muscles. Motion capture systems assessed the LLA and TKA. Statistical analyses included Shapiro-Wilk for normality and Levene’s test for homogeneity of variances. An independent t-test assessed for significance of differences in L2-S1 IVR, lumbar RoM and the LLA between groups, while a Mann Whitney U test was applied to data of the TKA and sEMG of muscles between groups. To compare differences in muscle activity between forward flexion and the return to standing phase within each group, a Wilcoxon signed-rank test was applied. A Spearman correlation was used to compare sEMG from each muscle against spinal kinematic data. Cohen’s d effect sizes (ES) was applied to muscle sEMG in flexion and return to standing within each group. The Hedges’ g ES was computed to compare sEMG of muscles and spinal kinematic variables between groups. Results: Healthy subjects showed reduced MF (ES = 0.4, p < 0.05), ILM (ES = 0.3, p < 0.05), and GM (ES = 0.7, p < 0.05) activity during flexion compared to the return to standing. LBP patients demonstrated decreased ILM (ES = 0.2, p < 0.05) and LGM (ES = 1.0, p < 0.05) activity during flexion but increased EOM activity (ES = 0.2, p < 0.05). Significant differences between LBP and healthy subjects in ILM activity were observed during the return to standing (ES = 0.9, p < 0.05). LBP patients exhibited a 9.2° reduction in lordosis (ES = 0.7, p < 0.05) and a significant loss in lumbar RoM (ES = 0.9, p < 0.05), but no correlation was found between sEMG and spinal kinematic variables. Conclusion: Healthy individuals displayed higher ILM activity, while LBP patients showed increased EOM activity and significant reductions in lumbar RoM and lordosis. Despite no significant correlation between muscle activity and spinal kinematics, the increased abdominal muscle activity and reduced erector spinae activity suggests that defensive bracing type strategies were employed.

ID: 1287

A081: Biomechanical study of pedicle screw pull-out strength in osteoporotic cancellous bone model-Jamshdi needle versus pedicle probe technique

Shival Tharmaseelan ¹ , Mohd Hezery Harun ¹ , Fadzrul Abbas Mohamed Ramlee ¹ , Mohd Na'im Abdullah ²

¹ University Putra Malaysia, Spine Unit, Department of Orthopaedics, Serdang, Selangor, Malaysia

² University Putra Malaysia, Department of Aerospace Engineering, Faculty of Engineering, Serdang, Selangor, Malaysia

Introduction: Spinal fusion surgery with pedicle screws is commonly performed to stabilize the spine of osteoporotic patients. However, securing a strong screw fixation in osteoporotic bone presents significant challenges due to the reduced bone density. This study aimed to compare the biomechanical performance in an osteoporotic bone model of pedicle screws inserted using two different techniques: Jamshidi needle technique and Pedicle Probe Technique as well as the influence of tapping on both these techniques. The research sought to determine if the surgical device used in aiding pedicle screw placement- Pedicle probe (Open Technique) and Jamshidi Needle (MIS technique) affects the eventual stability of screw in osteoporotic conditions. The findings of this study could enlighten surgical practices, potentially leading to improved clinical outcomes for patients suffering from osteoporosis-related spinal instability. Material and Methods: An in-vitro biomechanical comparative study was performed whereby pedicle screws were inserted into a standardized polyurethane foam model of Grade 10 mimicking osteoporotic bone. Cylindrical poly-axial pedicle screws of 6.5mm diameter and 45mm length made out of medical grade titanium alloy, Ti-6Al-4V were inserted using four different techniques: Jamshidi needle, Jamshidi needle with tapping, Pedicle Probe, and Pedicle Probe with tapping. The screws were inserted by a trained spine surgeon in a standardized manner across all groups, The constructs were subsequently attached to Material Testing System (MTS) 810 machine using a customized jig. A direct-load-to-fail test was performed where data was collected and tabulated into a force-displacement graph. The axial pull-out strength, axial stiffness, and displacement to failure of each construct was then extracted from the graph. Independent sample T-test was then used to compare and study association between the groups where p < 0.05 was considered statistically significant. Results: The Pedicle Probe Technique demonstrated superior pull-out strength (698.36 ± 16.34 N) compared to the Jamshidi needle technique (557.15 ± 4.52 N) (p < 0.05). A greater displacement to failure was also seen in for Pedicle Probe group (2.26 ± 0.04 mm) versus Jamshidi needle group (1.18 ± 0.06 mm) (p < 0.05). However, the Jamshidi needle technique exhibited higher axial stiffness (336.88 ± 23.24 N/mm) compared to (208.82 ± 7.82 N/mm) Pedicle probe technique (p < 0.05). In examining the influence of tapping on both techniques, results show significantly reduced pull-out strength and displacement to failure in the Pedicle Probe group. Conclusion: Pedicle Probe technique offers enhanced initial stability in osteoporotic bone as evidenced by the superior pull-out strength and displacement to failure. On the other hand, Jamshidi needle technique provides greater resistance to deformation demonstrated by higher axial stiffness. The use of tapping should be carefully considered especially whilst using Pedicle Probe technique as demonstrated by significantly reduced pull-out strength and displacement to failure. The choice of technique should be informed by specific clinical context balancing the need for initial stability, resistance to deformation and risk of screw failure.

Keywords: Pedicle Screw Fixation, Osteoporotic Bone Model, Biomechanical Comparison, Spinal Fusion Surgery, Jamshidi Needle, Pedicle probe

OP10: Novel Technologies and Innovations 2

ID: 178

A082: Novel implantable anesthetics for spine fixation surgery: first-in-human results

Hein Jonkman ^1,2 , Suzanne Bruins ² , Floris van Tol ² , Jasper Steverink ² , Lorin Benneker ³ , Ruth Geuze ⁴ , Paul de Baat ⁵ , Bas Oosterman ² , Jorrit-Jan Verlaan ^2,6

¹ Radboud University Medical Center, Medical Innovation and Technology, Nijmegen, Netherlands,

² SentryX, Utrecht, Netherlands,

³ Sonnenhof Hospital, Orthopaedic Surgery, Bern, Switzerland,

⁴ Elisabeth Tweesteden Hospital, Tilburg, Netherlands,

⁵ Catharina Hospital, Eindhoven, Netherlands,

⁶ University Medical Center Utrecht, Utrecht, Netherlands

Introduction: There is a troubling lack of effective pain treatments after major surgery. Opioids remain dominant despite their many drawbacks, resulting in worse clinical outcomes and higher costs. Locoregional anesthetics are increasingly employed, but their added value remains limited by their short duration of effect. BR-003 is a novel implantable anesthetic designed to address severe pain after spine fixation surgery. It consists of a ring-shaped biodegradable hydrogel that is easy to co-implant with regular pedicle screws. Unlike injections, BR-003 stays in place and delivers bupivacaine to the surgical site for more than three days. By reducing pain and opioid-related side-effects, BR-003 may help patients leave the hospital sooner and in better shape. In this study, BR-003 was tested in humans for the first time to assess safety and obtain an early indication of efficacy. Material and Methods: Open-label Phase Ib clinical trial on BR-003 safety and pharmacokinetics. Two cohorts of 6 patients were scheduled for posterior degenerative spine fixation in two hospitals. Cohort 1 received 4 pedicle screws with 4 BR-003 rings. Cohort 2 received 6 screws and 6 rings. In both cohorts, 3 patients were planned for minimally invasive surgery (MIS) and 3 for open procedures. The primary endpoint was the peak serum concentration of bupivacaine (Cmax). Secondary endpoints included additional pharmacokinetics, safety, and exploratory efficacy up to 6 weeks. Safety assessments included additional pharmacokinetics, adverse events, ECGs, X-rays, and blood tests up to 6 weeks after surgery. Vital signs, wound healing, and neurological status were assessed daily until discharge. Efficacy was explored by comparing back pain in rest (AUC-NRS-R) and opioid use (Morphine Milligram Equivalents, MMEs) in the first three days to a recent observational cohort undergoing the same type of surgery in the same hospitals. In MIS cohort 1, pre-emptive analgesia was restricted to assess the early effects of BR-003. Results: Eleven patients were included in the study in total. Mean bupivacaine Cmax was 148.6 (95% CI 119.4 to 177.9). The terminal half-life was 34.5 hours (95% CI 27.7 to 41.3). No serious adverse drug reactions transpired. Clinical assessments, blood chemistry, ECGs, and X-rays revealed no relevant abnormalities related to BR-003. In the first three days after surgery, total opioid use was 52% lower with BR-003 (mean MME 231 vs. 111), with a 36% reduction in back pain in rest (mean AUC-NRS-R 4.2 vs. 2.7). Opioid use on day 2 and 3 was low, providing opportunities for earlier discharge. Conclusion: BR-003 appears to be a safe and promising new way of delivering bupivacaine directly at the surgical site for more than 3 days after spine fixation surgery. Preliminary data from a Phase Ib trial revealed no safety concerns. Bupivacaine Cmax remained 10x below the known toxic threshold. A substantial reduction in pain and opioid use was found as compared to a recent observational cohort in the same hospitals. A large randomized controlled trial is planned to confirm these findings and study the impact of BR-003 on pain, opioid use, and early recovery.

ID: 2907

A083: Development and validation of a keypoint region-based convolutional neural network to automate thoracic Cobb angle measurements using whole-spine standing radiographs

Mert Dagli ¹ , Hasan Ahmad ¹ , Daksh Chauhan ¹ , Ryan Turlip ¹ , Kevin Bryan ¹ , Jonathan Sussman ¹ , Bhargavi Budihal ¹ , Connor Wathen ¹ , Yohannes Ghenbot ¹ , John Arena ¹ , Joshua Golubovsky ¹ , John Shin ¹ , Ali Ozturk ¹ , Jason Anari ¹ , Beth Winkelstein ¹ , William Welch ¹ , Jang Yoon ¹

¹ University of Pennsylvania, Neurosurgery, Philadelphia, United States

Introduction: Adolescent idiopathic scoliosis (AIS) affects a significant portion of the adolescent population, leading to severe spinal deformities if untreated. Diagnosis, surgical planning, and outcome assessments heavily rely on measuring the thoracic Cobb angle (TCA) using anteroposterior spinal radiographs. This study aimed to develop and validate an artificial intelligence (AI) tool utilizing a keypoint region-based convolutional neural network (R-CNN) to automate TCA measurements from coronal whole-spine standing radiographs. Secondary outcomes included comparison of model performance to other models prior reported in the literature. Material and Methods: This project was funded by an NIH grant (R21AR075971). This retrospective study was conducted following established guidelines, including STROBE, TRIPOD+AI, and CLAIM. Institutional Review Board (IRB) approvals were obtained from Penn Medicine and Children’s Hospital of Philadelphia (IRBs 852054, 22-020186), with a waiver of patient consent due to the retrospective design. The keypoint region-based convolutional neural network (R-CNN) was trained on “Dataset 16” from SpineWeb. This dataset consisted of 609 whole-spine anteroposterior X-ray images of adolescent idiopathic scoliosis (AIS) patients. Validation was performed using an institutional AIS registry containing 83 patients who underwent posterior spinal fusion (PSF) surgery. Performance metrics for automated thoracic Cobb angle (TCA) measurements were assessed, including mean absolute error (MAE), median absolute error (MedAE), mean squared error (MSE), symmetric mean absolute percentage error (SMAPE), and intraclass correlation coefficient (ICC). Statistical analyses and performance assessments were conducted using Python 3.11, with bootstrapping (10,000 resamples) to calculate 95% confidence intervals for the MedAE. Results: The keypoint R-CNN model was trained using “Dataset 16” and then validated on an independent dataset from 83 patients undergoing PSF for AIS correction. During validation, the keypoint R-CNN achieved an MAE of 2.22 (95% CI: 1.06-3.39), MedAE of 1.47 (0.89-3.15), MSE of 9.1, SMAPE of 4.29, and ICC of 0.98, significantly outperforming existing automated methods such as VLTENet and Auto-CA. By comparison, VLTENet achieved a SMAPE of 5.44 on the test subset of the AASCE dataset, which dropped to 13.9 when applied to external clinical data. The superior performance of the R-CNN on external datasets suggests greater generalizability. Notably, the SMAPE of 4.29 in this study outperformed Auto-CA, which had a SMAPE of 5.27, and the MAE of 2.22 was superior to the 2.51 reported by VLTENet. Conclusion: The keypoint R-CNN demonstrates exceptional accuracy in automating coronal TCA measurements and outperforms existing methods. Its further development, scaling, and adoption could streamline scoliosis screening, surgical planning, and postoperative assessment, improving overall patient outcomes and reducing manual workload. Further validation across diverse populations and imaging modalities is warranted.

ID: 1427

A084: Full-endoscopic anterior cervical discectomy, decompression and fusion (eACDF) for degenerative disk disease and cervical myelopathy

Christian Morgenstern ¹ , Rudolf Morgenstern ²

¹ Morgenstern Institute of Spine, Centro Médico Teknon, Barcelona, Spain,

² Endospine SLU, El Tarter, Canillo, Andorra

Introduction: Despite increasing popularity of endoscopic spine procedures, adoption of the endoscopic anterior cervical approach has been lagging. Main reasons are concerns about the safety of the percutaneous anterior cervical approach and the inability to place an interbody cervical cage after endoscopic discectomy to achieve fusion. To overcome these limitations, we have developed novel approach instrumentation that allows a safe and reproducible endoscopic anterior approach to the cervical spine under direct endoscopic visualization to achieve full-endoscopic anterior cervical discectomy, decompression and fusion (eACDF). Aim of this study is to evaluate the feasibility, the clinical and radiologic outcome, as well as post-operative complications of eACDF for degenerative disk disease and cervical myelopathy. Material and Methods: This is a prospective case series study. Inclusion criteria comprised degenerative disk disease, central canal stenosis and symptomatic cervical myelopathy. Exclusion criteria comprised infection, tumor and vertebral body fracture. Surgically, a percutaneous approach to the cervical spine was performed with novel instrumentation (Unintech GmbH, Germany) that allows safely bypassing anatomic neck structures. Annulotomy was performed with a crown reamer under direct endoscopic vision. Full-endoscopic discectomy was performed without the need of a retractor. Constant irrigation allows excellent visualization of posterior endplates and decompression of the spinal canal. Finally, novel retractor blades allow percutaneous placement of a standard zero-profile cervical interbody cage under fluoroscopic imaging. Visual Analogic Scale (VAS) and Neck Disability Index (NDI) scores were evaluated pre-operatively and post-operatively at hospital discharge, as well as 1, 3, 6, 12 and 24 months. Post-operative radiologic evaluation was performed with a standing X-ray at hospital discharge and at 12 months follow-up. Statistical analysis was performed with Student’s paired T-Test. Statistical significance was defined for p < 0.01. Results: 22 patients (12 (55%) female) were included with a mean age 53.7 ± 13.2 years. A total of 31 cages were placed, including 9 two-level cases. Total mean follow-up was 28.8 ± 19.2 months. VAS neck scores improved from 7.2 ± 2.2 pre-op to 2.2 ± 1.8 post-op at latest follow-up (p < 0.01). VAS arm scores improved from 5.1 ± 3.0 pre-op to 1.5 ± 1.6 post-op at latest follow-up (p < 0.01). NDI scores improved from 28.1 ± 10 pre-op to 15.2 ± 9.9 post-op at latest follow-up (p < 0.01). The fusion rate of the interbody cages was 95%. The patient was mobilized a median of 5 hours after surgery and hospital discharge in less than 24 hours. Post-operative complications included two cases with transitory muscle weakness of left finger flexion that resolved after 2 to 4 weeks of physiotherapy and intramuscular cortisone treatment. One case with asymptomatic fracture of a C5 vertebral body was treated conservatively by wearing a stiff neck for 6 weeks. No cases of post-operative hoarseness, hematoma and bleeding were reported. Conclusion: Full-endoscopic ACDF is a promising technique that allows successful treatment of degenerative disk disease and cervical myelopathy with satisfactory preliminary results after more than 2 years follow-up. No retractor is used during discectomy, minimizing risk of post-operative hoarseness, bleeding and dysphagia.

ID: 1020

A085: Predicting outcomes in microdiscectomy surgery with applied machine learning

Jack Roadley ¹ , Quinlan Bucklak ^2,3 , Jainam Shah ⁴ , Tony Goldschlager ^2,5

¹ University of Queensland, School of Medicine, Brisbane, Australia,

² Monash Health, Department of Neurosurgery, Melbourne, Australia,

³ University of Notre Dame, School of Medicine, Sydney, Australia,

⁴ Monash University, School of Medicine, Melbourne, Australia,

⁵ Monash Health, Department of Surgery, Melbourne, Australia

Introduction: Microdiscectomy surgery is a common procedure used to treat lumbar disc herniation (LDH), a condition causing significant lower back pain and sciatica. Despite its widespread use, outcomes vary, with some patients experiencing re-herniation. Accurate prediction of postoperative outcomes could improve patient counselling and treatment planning. This study explores the application of machine learning models to predict re-herniation at 12 months using preoperative clinical and demographic data. Material and Methods: This multi-centered study used data from a randomised controlled trial involving 211 patients who underwent microdiscectomy. After addressing missing data, 152 cases were analysed. Logistic regression was first applied to determine significant covariates, followed by the development of supervised learning classifiers, including Random Forest, AdaBoost, and Neural Networks. Model performance was evaluated using metrics such as the Matthews correlation coefficient (MCC) and area under the receiver operating characteristics curve (ROC-AUC). Results: Significant predictors of re-herniation included smoking status and emergency department (ED) presentations. Smokers were 11 times more likely to experience re-herniation, and those with frequent ED visits were 19 times more likely to do so. The Random Forest model achieved the highest predictive performance, with an MCC of 0.47 and an AUC of 0.69. Application of SMOTE improved sensitivity but decreased specificity in most models. Conclusion: Machine learning models, particularly Random Forest, demonstrated moderate predictive ability for re-herniation following microdiscectomy. Significant preoperative factors like smoking and ED visits were strongly associated with poor outcomes. These findings suggest that machine learning can enhance clinical decision-making by identifying high-risk patients, allowing for more personalised treatment strategies.

ID: 923

A086: Coccygectomy - A novel technique

Nigil Palliyil ¹ , Jim Francis Vellara ¹ , Masood Shafafy ² , Vasanth Bharathidasan ³

¹ Amrita Institute of Medical Sciences, Spine Division, Orthopaedics, Kochi, India,

² Queens Medical Centre, Centre for Spinal Studies and Surgery, Nottingham, United Kingdom,

³ Amrita School of Medicine, Kochi, India

Introduction: Coccygectomy is recognised as a treatment option for chronic refractory Coccydynia, but is often known to have higher rates of wound complications such as wound dehiscence and surgical site infections. To address these issues, different surgical approaches have been explored, including Para median incisions, Para median curvilinear incisions, Z-plasty techniques etc. In our case series, we describe a novel technique using a transverse skin incision for coccygectomy and assess the clinical outcomes and patient satisfaction associated with this approach. Material and Methods: Patients suffering from refractory Coccydynia, resistant to conservative therapies, underwent Coccygectomy using a transverse skin incision between 2011 and 2023. Demographic data for all patients were collected from electronic medical records retrospectively. Informed consent was obtained from each patient for clinical photography for medical publication, adhering to institutional policies. The primary outcome measure assessed the postoperative wound healing. Secondary outcomes included the evaluation of Visual Analog Scale (VAS) scores and overall patient satisfaction. Results: 16 patients (3 males and 13 females) fulfilled the inclusion criteria. The mean age of the study population was 29.5 years (range 7-55 years). 2 patients (12.5%) experienced wound dehiscence that required re-suturing and 1 (6.25%) patient had a superficial wound infection which was treated with oral antibiotics. None of the patients had deep infection. The mean VAS improved from 8.5 ± 1.5 (pre-operatively) to 3.2 ± 2.8 (post-operatively). 13 patients had an excellent outcome after the procedure while 3 had a fair outcome. Conclusion: A transverse skin incision appears promising as an alternative to the conventional midline incision, potentially lowering the incidence of delayed wound healing and surgical site infections.

ID: 1757

A087: Dynamic changes in mechanical properties of the adult rat spinal cord after injury

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

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

Introduction: Spinal cord injury (SCI), a debilitating medical condition that can cause irreversible loss of neurons and permanent paralysis, currently has no cure. However, regenerative medicine may offer a promising treatment. Understanding and characterizing the mechanical properties of the spinal cord tissue is very important. This study aimed to perform comprehensive mechanical characterisation of adult rat spinal cord tissues after crush injury via microindentation tests. The specific objectives were to (1) measure the elastic stiffness and viscosity of the spinal cord tissue at different time points postinjury and (2) explore the possible spatiotemporal changes in the tissue viscoelastic properties. Material and Methods: Adult female Sprague-Dawley rats weighing 250 ± 10 g were utilized. The crush injury model was established. This study comprised two distinct phases. The first (1) was an exploratory test phase, wherein the initial mechanical information regarding the ex-vivo thoracic spinal cord tissue was gathered and characterised. The second (2) comprised a full-scale test phase wherein the tested procedures were performed to systematically explore the dynamic viscoelastic properties of ex-vivo spinal cord tissue. Mechanical characteristics were evaluated ex vivo using a Mach-1 Model V500css Device (Biomomentum Inc., Laval, QC, Canada). In the exploratory test phase, indentation experiments were performed on the ex-vivo spinal cord specimens to quantify the tissue force-relaxation response with loading ramps at 0.10 mm/s at a target indentation depth of 0.25 mm and holding times of 30 s. To investigate the spatial distribution of the elastic modulus of the spinal cord, stiffness maps were created based on the indentation measurements. Statistically significant differences were demonstrated with P values less than 0.05. Results: Our results demonstrated that in comparison with uninjured spinal cord tissue, the injured tissues exhibited lower stiffness (median 3281 Pa versus 9632 Pa; p < 0.001) but demonstrated elevated viscosity (median 80% versus 57%; p < 0.001) at 3 days postinjury. Between 4 and 6 weeks after SCI, the overall viscoelastic properties of injured tissues returned to baseline values. At 12 weeks after SCI, in comparison with uninjured tissue, the injured spinal cord tissues displayed a significant increase in both elasticity (median 13698 Pa versus 9920 Pa; p < 0.001) and viscosity (median 64% versus 58%; p < 0.001). Conclusion: Three days after SCI, the spinal cord tissue at the injury site exhibited the lowest stiffness and modulus but demonstrated elevated viscosity compared to the nearby uninjured tissue. Between 1 and 6 weeks after SCI, the overall viscoelastic properties returned to baseline values at different rates, and the window period that transiently obliterated the mechanical difference lasted for a period of ∼2 weeks. Six weeks postinjury, the injured spinal cord tissues displayed a continuous and significant increase in both elasticity and viscosity synchronously until the end of the observation period (i.e. week 12 postinjury). This work constitutes the first quantitative mapping of spatiotemporal changes in spinal cord tissue elasticity and viscosity in injured rats, providing a mechanical basis of the tissue for future studies on the development of biomaterials for SCI repair.

ID: 907

A088: Evaluation of the accuracy and precision of augmented reality for pedicle screw placement in the cervical spine

Lisa Tamburini ¹ , Anthony Viola ² , Rohan Patel ¹ , Tomer Korabelnikov ¹ , Raghunandan Nayak ¹ , Justin King ¹ , Scott Mallozzi ¹ , Isaac Moss ¹ , Hardeep Singh ¹

¹ University of Connecticut, Department of Orthopaedics, Farmington, United States,

² Valley Orthopaedic Specialists, Shelton, United States

Introduction: Augmented reality (AR) has gained popularity in spine surgery. Head mounted AR devices superimpose a 3D reconstructed spine on patient anatomy which has been shown to assist with accurate placement of lumbar spine pedicle screws. We evaluated the accuracy and precision of AR in cervical spine (CS) pedicle screw placement. Material and Methods: 7 fresh-frozen cadaveric CS specimens from C2-T1 were used. Soft tissues were removed and specimen were potted in polyvinyl chloride (PVC) tube with PMMA all-purpose self-cure acrylic repair material. Wood blocks were attached to PVC tubes to allow for attachment to surgical table. Four 2-mm screws were placed in lamina as fiducial markers to ensure accuracy. Pre-operative computed tomography (CT) scans were obtained and uploaded to the Augmedics system. Augmedics AR navigation system was utilized for placement of C2-C7 pedicle screws. Screen shots were taken of initial trajectory, planned trajectory, and final navigation screw placement. Post-operative CT scan was obtained. Time from initial CT scan to start of navigation and total navigation time were recorded. Radiation dose information was obtained. Intraoperative CT was used to compare difference in angular trajectory of planned trajectory and navigated screw placement. Navigated screw placement trajectory was compared to post-operative CT scan. Measurements were performed by on axial and sagittal images. Trigonometric functions were used to determine linear deviation of the screw tip. Post-operative CT scans were graded using Gertzbein-Robins classification. Results: 82 pedicle screws were placed, C2 on one specimen was excluded as it was inaccessible. All fiducial markers were accurately registered. Average time from CT scan to navigation was 2 minutes and 19 seconds and average total navigation time was 33 minutes and 46 seconds. The average radiation exposure time was 26.01 ± 2.36 seconds and the average dose-length product (DLP) was 551.15 ± 74.04 mGy-cm. The mean angular deviation between planned trajectory and navigated screw placement at all levels was 2.63° ± 2.65 and 3.08° ± 2.32 in the axial and sagittal planes. The mean calculated linear deviation from planned trajectory to navigated screw placement at all levels was 1.11 mm ± 1.04 and 1.24 mm ± 0.84 in the axial and sagittal planes. The mean angular deviation between navigated and actual screw placement at all levels was 3.68° ± 4.15 and 2.44° ± 2.17 in the axial and sagittal planes. When divided into upper (C2-C4) and lower (C5-C7) CS levels, mean angular deviation in the upper CS was 4.56° and 2.88° in the axial and sagittal planes and in the lower CS was 2.96° and 1.92° in the axial and sagittal planes. The mean calculated linear deviation between navigated and actual screw placement at all levels was 1.51 mm ±1.53 and 1.02 mm ± 0.88 in the axial and sagittal planes. 95% of screws were classified as accurately placed, grades A or B, using Gertzbein- Robbins Classification. Accuracy was 95% in the upper CS and 98% in the lower CS. Conclusion: AR can assist in placement of pedicle screws in the CS. Accuracy and precision both improved when comparing upper CS to lower CS levels.

ID: 455

A089: A machine learning approach to predict root-level intraoperative neuromonitoring (IONM) loss in adult spine deformity surgery

Nathan Lee ¹ , Lawrence Lenke ² , Varun Arvind ² , Ted Shi ² , Alexandra Dionne ² , Chidebelum Nnake ² , Mitchell Yeary ² , Michael Fields ² , Matthew Simhon ² , Anastasia Ferraro ² , Matthew Cooney ² , Erik Lewerenz ² , Justin Reyes ² , Steven Roth ³ , Chun Wai Hung ⁴ , Justin Scheer ⁵ , Thomas Zervos ² , Earl Thuet ⁶ , Joseph Lombardi ² , Zeeshan Sardar ² , Ronald A. Lehman ² , Benjamin Roye ² , Michael Vitale ² , Fthimnir Hassan ²

¹ Midwest Orthopaedics at RUSH, Chicago, United States,

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

³ University of Florida Medical Center, Gainesville, United States,

⁴ Houston Methodist, Houston, United States,

⁵ Cedar Sinai Medical Center, Los Angeles, United States,

⁶ New York Presbyterian/Och Spine Hospital, New York, United States

Introduction: Quantifying a patient’s risk for neuro deficit during adult spine deformity (ASD) surgery remains challenging given the myriad of perioperative factors. Therefore, a ML approach was used to generate an accurate scoring system to predict root-level IONM data loss. Methods: 735 ASD patients from a single center (2015-2023) were studied. 193 distinct perioperative variables were included (demographics, diagnosis, medical history, physical exam, operative factors, labs, preop/intraop x-rays, preop MRI/CT). Root-level IONM data loss was defined as either complete signal loss or when motor-evoked potentials met institutional warning criteria and was reviewed with the senior member of the IONM team. Patients were randomly allocated into training/testing (75% / 25%) cohorts to train a random forest and logistic regression machine learning classifier. Threshold values for features were calculated from trained random forest model, and scores were derived by rounding up weights from the logistic regression model. Variables in the final scoring calculator were selected to optimize predictive performance (accuracy/sensitivity/specificity/area under the receiver operating characteristic curve (AUROC)). Analysis was performed using scikit-learn (v.0.24.2) in Python (v.3.9.18). Results: The rate of root-level IONM loss was 5% (39/735) and most involved the tibialis anterior (72%), extensor hallucis longus (56%), and vastus (33%). Of those with root-level loss, 26% had severe motor deficit (≤ g rade 3 anti-gravity strength) immediately postop. Thru the ML approach, 5 features were included. Calculated scores for Lumbar Foraminal/Lateral Recess Stenosis, Preop to Intraop Delta in Hematocrit ≥ 12, Lower Instrumented Level at Ilium, Dural Tear, and Three Column Osteotomy were 3, 1, 1, 1, and 1 point, respectively. An aggregate score of ≤ 3 had an associated risk of nerve-root IONM loss of 1.7%, while those with total scores ≥ 6 had a rate of 60%. On the test cohort, the scoring system achieved an accuracy of 86.4%, sensitivity of 80%, specificity of 86.6%, and an AUROC of 0.83. Conclusions: This study introduces the first ML-derived scoring system that can be used preoperatively to predict root-level IONM motor data loss for ASD patients undergoing reconstructive surgery with excellent model performance.

ID: 1661

A090: Outcomes of lumbar interbody fusion using hydroxyapatite-infused polyetheretherketone cages: no significant advantage in adding BMP

Bahador Athari ¹ , Henry Avetisian ¹ , William Karakash ¹ , Andy Ton ² , Marcel Dreischarf ³ , David Oka ³ , Ram Alluri ¹ , Raymond Hah ¹ , Jeffrey C. Wang ¹

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

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

³ Innovasis, Inc, Salt Lake City, United States

Introduction: Lumbar interbody fusion (LIF) using cages has become a cornerstone in spine surgery, helping to restore disc height, increase foraminal diameter, and enhance lumbar lordosis. Achieving solid fusion is critical, and many surgeons incorporate bone morphogenic protein (BMP) to improve fusion rates. However, BMP carries significant risks, such as increased costs and potential complications, including ectopic bone formation and vertebral osteolysis. With advancements in cage materials like hydroxyapatite (HA)-infused polyetheretherketone (PEEK), there is potential to achieve high fusion rates without BMP. This study compares patient-reported outcome measures (PROMs) and fusion rates between patients receiving BMP and those using only local bone grafts with HA-infused PEEK cages in a large multicenter registry, aiming to assess the necessity of BMP in these procedures. Methods: We conducted a retrospective analysis of patients who underwent single-level LIF with HA-infused PEEK cages. Patients were divided into two groups: (1) the control group, which only received either local bone or iliac crest grafts, and (2) the BMP group, which received bone morphogenic protein. Patients undergoing revision surgery, or with tumor or infection, were excluded. PROMs (Visual Analog Scale [VAS] for back pain, Oswestry Disability Index [ODI]) and fusion rates were assessed at 6 weeks, 3 months, 6 months, and 12 months. Fusion was evaluated using dynamic radiographs, with less than 4 degrees of range of motion (RoM) considered successful fusion. Results: Among 654 patients (mean age: 59.5 ± 14.2 years; 43% male), 507 received local grafts and 147 received BMP. Distribution of surgical approaches included anterior (ALIF, 31.3%), posterior (PLIF, 28.7%), transforaminal (TLIF, 25.8%), and lateral (LLIF, 14.1%) LIF. Preoperative ODI was 50.1 ± 15.2 in the BMP group and 48.4 ± 17.0 in the control group, while pre-op VAS scores were 71.1 ± 21.0 and 70.9 ± 23.0, respectively. At 12 months, ODI improved to 21.7 ± 18.2 in the BMP group and 24.3 ± 19.5 in the control group, with no significant differences between groups (ODI, p = 0.751; VAS, p = 0.999). Fusion rates were similar between the groups at 12 months (BMP: 95%; control: 93%). Preoperative RoM was 4.9 ± 4.2 degrees for the BMP group and 3.5 ± 3.9 degrees for the control group. By 12 months, RoM had reduced to 0.8 ± 0.6 degrees in the BMP group and 1.0±1.2 degrees in the control group, with no significant differences at 6 or 12 months (p = 0.999). There were 13 unrelated complications, with no revisions required due to HA-infused PEEK cages. Conclusion: Our findings suggest that HA-infused PEEK cages, when combined with local bone grafts, offer fusion rates and patient-reported outcomes comparable to those achieved with BMP. The use of HA-PEEK cages may help avoid BMP-related complications and reduce costs, offering a safe and effective alternative for lumbar interbody fusion.

OP11: Spinal Oncology 2

ID: 2746

A091: Optimizing dural closure technique in cases of intradural spine tumor surgery: report of a controlled case series and systematic literature review

Paula Klurfan ¹ , Jed Lazarus ¹ , Michael Fehlings ¹

¹ Toronto Western Hospital, Neurosurgery, Toronto, Canada

Introduction: Post operative Cerebrospinal Fluid (CSF) complications are common and concerning problems after spinal tumor surgery and other spinal surgery were the dural plane is breached (1-28.6%). These include wound CSF leaks and formation of a pseudomeningocele leading to infections, intracranial hypotension and secondarily complications related to prolonged bed rest and use of antibiotics among others. In addition, CSF leak is associated with increased length of stay, hospitalization costs and mortality. Multiple techniques and materials have been used in an effort to reduce this complication with varying results. These include the use of polyethylene glycol (PEG) sealants, dural and fat/muscle grafting. Despite this, the reported number of CSF related complications remains high with great variation between studies. Hemostatic and sealing patches are novel approved materials that have been successfully used in the areas of cardiovascular and general surgery and more recently for cranial and spinal dural repair. One such product, Hemopatch is made of bovine collagen backing and pentaerythritol polyethylene glycol ether tetra-succinimydyl glutarate (NHS-PEG) monomer that seals and induces hemostasis of bleeding tissue. In this study we review our experience with the Hemopatch in the management of dural closure after intradural spinal tumor surgery (ISTS) and provide a systematic review of the literature. Materials and Methods: We conducted a single center, ambispective controlled case series review of 40 consecutive ISTS cases. All patients were operated by the senior author during 2023 and 2024. All cases had a standard management with watertight primary dural closure with a neurolon 4.0 suture. In 20 cases, a PEG sealant and grafting with muscle, fat or dural parch was performed. In 20 cases, Hemopatch was placed over the dural closure. All patients were managed with a surgical subfascial JP drain and flat bed rest in the initial post operative period. We reviewed the patients’ age, gender, tumor diagnosis, length of hospital stay (LOS), CSF leak incidence, postoperative infections, and associated complications. A systematic review of the literature was undertaken following PRISMA standards. Results: Six (30%) patients in the conventionally treated (control) group had a CSF leak postoperatively. Three patients had minor CSF wound leaks that were treated with extra wound suturing and bed rest. Two patients required a lumbar drain and prolonged bed rest and two (10%) patients required reoperation and dural repair. One patient required wound debridement and antibiotics for a local infection. To date, no CSF leak complications have been encountered in the group of ISTS cases treated with the Hemopatch as an adjunct to dural closure and all cases have been rapidly mobilized without complication. The systematic review revealed a great range of techniques and materials for dural closure with various results. Conclusion: Although the vast majority of intradural tumors are benign and are generally associated with good prognosis, the risk of CSF leak and adequate dural closure remains a challenge. The use of a hemopatch to assist in dural closure appears promising and based on our case series has been associated with excellent results.

ID: 1141

A092: Utility of 3D-printed models in the surgical planning for primary spine tumors: a survey of international spinal oncology experts

Anthony Mikula ¹ , Laurence Rhines ² , Shalin Patel ³ , Zachary Pennington ¹ , Mohammed Karim ⁴ , Jonathan Morris ⁵ , Karthik Tappa ³ , Christopher Alvarez-Breckenridge ² , Rob North ² , Claudio Tatsui ² , Peter Rose ⁴ , Michelle Clarke ¹ , Justin Bird ³

¹ Mayo Clinic, Neurological Surgery, Rochester, United States,

² MD Anderson Cancer Center, Neurological Surgery, Houston, United States,

³ MD Anderson Cancer Center, Orthopedic Oncology, Houston, United States,

⁴ Mayo Clinic, Orthopedic Oncology, Rochester, United States,

⁵ Mayo Clinic, Radiology, Rochester, United States

Introduction: Spinal column tumors can be technically challenging to resect given the complex surrounding anatomy. In primary spinal column tumor surgery, models detailing the tumor location and surrounding anatomy have been described in limited case reports and case series, but further evaluation of the technology’s potential benefits is needed. The purpose of this study was to further explore the utility of a patient specific 3D-printed model for planning the surgical resection of primary spinal column tumor cases by surveying a group of international spinal oncology experts. Material and Methods: A survey of individual members of an international study group of spinal oncology surgeons was performed. Participants were provided a clinical vignette, pathologic diagnosis, and pre-operative imaging for three primary spinal oncology cases. Study participants provided a free text surgical plan for resection and were then presented an associated 3D printed model for each case and asked to re-evaluate their surgical plan. Results: Ten spinal oncology surgeons participated in the study, representing nine institutions across five countries. Four of the surgeons (40%) made significant changes to their surgical plan after reviewing the 3D models, including sacrifice of an additional nerve root to obtain negative margins, sparing an SI joint that was originally planned for inclusion in the en bloc resection, adjusting the location of osteotomy cuts, changes to the number of surgical stages and/or staging order, and preservation of neurology that was originally planned for sacrifice. The overall impression of the 3D models was positive, with 90% of the participants stating they found the 3D model useful in developing a surgical plan. Conclusion: Surgical planning for resection of primary spinal column tumors is challenging and time intensive. 3D printed patient specific surgical models may be an additional tool that can augment surgical planning and execution by improving the chance of accomplishing surgical resection goals and minimizing morbidity.

ID: 2126

A093: Days spent alive and at home after treatment of spinal metastases: measurement of a patient centred outcome with population health data

Husain Shakil ¹ , Armaan Malhotra ¹ , Alexander Kiss ² , Vishwathsen Karthikeyan ¹ , Christopher Lozano ¹ , Christopher Witiw ¹ , Donald Redelmeier ² , Jefferson Wilson ¹

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

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

Introduction: Days spent alive and at home (DAH) is a patient-centered outcome that has not been described for patients with spinal metastases. In this study, we measure DAH after initial treatment of spinal metastasis, investigate the optimal follow-up period for measurement, assess the validity of DAH as an outcome measure, and estimate the minimal important difference (MID) in the outcome. Material and Methods: A retrospective analysis was conducted of population health data from 2007 to 2019 in Ontario, Canada. Primary study outcomes include DAH and survival at 30-days, 90-days, 180-days, 365-days, and 730 days of follow-up after first treatment of a spinal metastasis. We fit a multivariable quantile regression model to identify patient factors associated with significant differences in DAH. The MID was estimated using both distributional and anchor-based methods. Results: We identified 36, 233 patients treated for spinal metastases. Mean age was 64.4 years (13.4 SD), and most common primary cancers were lung (N = 9973, 27.5%), breast (N = 5650, 15.6%), prostate (N = 5470, 15.1%), and gastrointestinal (N = 3109, 8.6%). Median survival for the cohort was 152 days (95% CI 148 to 155 day). Median DAH-180 was 114 days (95% CI 112 to 117), and closely approximated DAH-365 (median 120; 95% CI 117 to 123), and DAH-730 (median 121; 95% CI 118 to 125). Older age, frailty, prior ICU admission, increased baseline health resource utilization, metastasis secondary to melanoma, hepatobiliary or lung cancer, and greater distance between a patient’s home and the treating cancer center were associated with significantly decreased median DAH-180 (p < 0.01, Wald’s test). These findings support construct validity of DAH-180 at the patient health, social, and cancer level. The estimated minimally important difference (MID) in DAH-180 was 14 days. Conclusion: This study presents real world data on time spent at home after treatment of a spinal metastasis. Our study found DAH-180 demonstrated both construct and predictive validity as a patient-centered outcome measure, with a MID of approximately 14 days. Future research is required to consider patient perspectives and compare DAH to validated patient reported outcomes.

ID: 1601

A094: Minimal clinically important differences in the Spine Oncology Study Group Outcomes Questionnaire (SOSGOQ2.0) in patients with symptomatic spinal metastases

Anne Versteeg ¹ , Arjun Sahgal ² , Ilya Laufer ³ , Laurence Rhines ⁴ , Daniel Sciubba ⁵ , Michael Weber ⁶ , Aron Lazary ⁷ , Stefano Boriani ⁸ , James Schuster ⁹ , Chetan Bettegowda ¹⁰ , Michael Fehlings ¹¹ , Michelle Clarke ¹² , Paul Arnold ¹³ , Ziya Gokaslan ¹⁴ , Charles Fisher ¹⁵

¹ University of Toronto, Orthopaedic surgery, Toronto, Canada,

² Sunnybrook Health Sciences Centre, Radiation Oncology, Toronto, Canada,

³ NYU Langone Health, Department of Neurosurgery, New York, United States,

⁴ The University of Texas MD Anderson Cancer Center, Department of Neurosurgery, Houston, United States,

⁵ Northwell Health, Department of Neurosurgery, Manhasset, United States,

⁶ McGill University and Montreal General Hospital, Division of Surgery, Toronto, Canada,

⁷ National Center for Spinal Disorders and Buda Health Center, Budapest, Hungary,

⁸ University of Bologna, Bologna, Italy,

⁹ Hospital of the University of Pennsylvania, Department of Neurosurgery, Philadelphia, United States,

¹⁰ Johns Hopkins University School of Medicine, Department of Neurosurgery, Baltimore, United States,

¹¹ University of Toronto and Toronto Western Hospital, Department of Neurosurgery, Toronto, Canada,

¹² Mayo Clinic, Department of Neurosurgery, Rochester, United States,

¹³ Carle Illinois College of Medicine, Department of Neurosurgery, Urbana, United States,

¹⁴ The Warren Alpert Medical School of Brown University and Rhode Island Hospital and The Miriam Hospital, Department of Neurosurgery, Providence, United States,

¹⁵ University of British Columbia and Vancouver General Hospital, Orthopaedic surgery, Vancouver, Canada

Introduction: The Spine Oncology Study Group Outcomes Questionnaire (SOSGOQ2.0) is a validated tool that measures patient reported health related quality of life (HRQOL) in patients with spinal metastases. It is currently however unknown what absolute change in SOSGOQ2.0 represents a clinically meaningful change for a patient which causes challenges with the interpretation of the SOSGOQ2.0 total score or domain scores. The aim of this study was therefore to determine the minimally clinically important difference (MCID) for the SOSGOQ2.0 in patients with spinal metastases. Material and Methods: An international multicenter prospective observational study including patients with spinal metastases who were treated with surgery and/or radiotherapy was conducted by the AO Spine Knowledge Forum Tumor. HRQOL was evaluated using the SOSGOQ2.0 at pre-defined time points. The MCID values for the SOSGOQ2.0 were determined using both distribution-based as well as anchor-based methods. For the anchor-based method, the post-therapy questions of the SOSGOQ2.0 served as the anchor. Spearman correlation coefficients were calculated to confirm a correlation of ≥ 0.30 or higher between the SOSGOQ2.0 post-therapy questions and the SOSGOQ2.0 overall score and domain scores. A response of “somewhat better or much better” in the post-therapy questions was used to classify improvement. MCID values from the distribution-based methods were derived using the statistical characteristics of the study population and compared to the anchor-based results. Results: A total of 317 patients had SOSGOQ2.0 data available at baseline and at 12 weeks post-treatment and were included in the final analyses. Statistically significant MCID scores were found for the SOSGOQ2.0 total score and all the individual domain scores. For deterioration, only the MCID scores for the SOSGOQ2.0 total score and mental health domain demonstrated to be significant. The MCID value for improvement in the SOSGOQ2.0 total score, physical function, pain, mental health and social function domain score based on the anchor based are 16.5, 10.2, 26.0, 14.4 and 17.2 respectively. Based on the distribution-based approach there was moderate agreement between the anchor-based approach and the 0.5 standard deviation values for improvement. Conclusion: This is the first study to report MCID values for the SOSGOQ2.0 total score and domain scores. The results of this study will help both clinicians as well as researchers with the interpretation of the effect of treatment for painful spinal metastases on patient reported HRQOL.

ID: 543

A095: Survival after surgery for spinal metastases from prostate cancer

Johan Wänman ¹

¹ The Faculty of Medicine, Diagnostic and Intervention, Umeå, Sweden

Background: Bone metastases occur in more then 80% of patients with prostate cancer and the spine is the most common location with a severe risk for development of metastatic spinal cord compression (MSCC). Surgery combined with radiotherapy has shown better outcomes for patients with MSCC compared to radiotherapy alone, but surgery is also associated with risk for complications, comorbidity and mortality. Estimation of postoperative survival is a key component in the complex selection process for patients that may benefit from surgery. This study aimed to analyse the prognostic factors for survival after surgery for MSCC in patients with prostate cancer in a large national cohort. Material and Methods: This is a retrospective observational multiregistry cohort study. The data was derived from the Swedish National Spine Surgery Register (Swespine), the Swedish National Prostate Cancer Register (NPCR) and the database named Prostate Cancer data Base Sweden (PCBaSe). Epidemiological data on primary tumor diagnosis (age, tumor stage, Gleason score, and serum level of prostate-specific antigen-PSA), MSCC diagnosis (age, MRI, hormone status, neurological function, the Charlson comorbidity index, type of surgery), and postoperative survival were analyzed. The Frankel score was used to categorize the neurological function prior to surgery. Postoperative survival was estimated by Kaplan-Meier analysis, and survival curves were compared using the log-rank test. A multivariate Cox regression model for survival was constructed with the Charlson comorbidity index, age, ambulation, and hormone status at the time of surgery as covariates. Results: In total 306 patients with MSCC from prostate cancer were included in the study. The thoracic spine was the most common location for the metastatic lesion (n = 191). One hundred thirty patients were ambulatory and 161 were non-ambulatory, 15 patients had missing information about ambulation prior to surgery. Posterior approach was performed in 290 (95%) patients. Eighty-eight patients were classified as having hormone-naïve prostate cancer and 218 patients as having castration resistant prostate cancer (CRPC) at the time of surgery. Patients with hormone-naïve prostate cancer had a median postoperative survival of 20 months (12-27, 95% CI) compared to 8 months (7-9, 95% CI) for patients with CRPC (p < 0.001). Only hormone status had a significant impact on postoperative survival in the cox proportional hazard model (p < 0.001). Conclusion: Hormone status is a strong predictor of postoperative survival in patients with MSCC from prostate cancer.

ID: 1334

A096: Analysis of postoperative sagittal alignment changes after resection of primary extradural spinal tumors and stabilization: a single center retrospective study

Paul Warnke ¹ , Cara Maria Schmitt ¹ , Alexander Thomas ¹ , Julia Luckow ¹ , Luis Rodriguez Pino ¹ , Schaser Klaus-Dieter ¹ , Disch Alexander C. ¹ , Uwe Platz ¹

¹ University Hospital Carl Gustav Carus at the TU Dresden, University Center for Orthopaedics, Trauma and Plastic Surgery, University Comprehensive Spine Center, Dresden, Germany

Introduction: Extradural primary spinal tumors are rare neoplasms, which mostly originate from bone or soft tissue, recommended for Enneking appropriate resection and subsequent reconstruction of the spine. Advancements in surgical resection and adjuvant therapies have shown to significantly increase patients` overall survival. Sagittal malalignment is a crucial factor in spinal fusion surgery, contributing to adjacent segment degeneration (ASD) and instrumentation failure. The influence of postoperative malalignment, health related quality of life (HQL) and post-operative implant failure is not clear in that cohort of patients. Methods: Between 2017 and 2024, a cohort of 120 patients with extradural primary spinal tumors was studied using pre- and postoperative radiological examination (RE). Among these, 40 underwent tumor resection and spinal reconstruction, with 20 having lumbar spine reconstructions. Only 10 of these patients had both pre- and postoperative standing X-rays available. Radiographic assessments were conducted using specialized spine angle measurement software to evaluate both global and regional sagittal alignment parameters, including pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), lumbar lordosis (LL), the L4-S1 angle (L4-S1), and the local SA of the instrumented vertebrae. These biomechanical parameters were correlated with (HQL) metrics such as EQ-5D VAS scores through regression and correlation analysis. The study was approved by the local ethics committee. Results: We observed significant changes in pre- and postoperative spinopelvic alignment, notably a shift towards a less lordotic orientation with a 95% confidence interval (CI) of -10.99° ± 6.29° (p = 0.0034). Significant changes were also seen in lumbar lordosis (LL), sacral slope (SS), and the L4-S1 angle (LL: p = 0.02, 95% CI: -12.96° ± 7.8°; SS: p = 0.006, 95% CI: 8.3° ± 5.3°; L4-S1: p = 0.01, 95% CI: -10.8° ± 7.8°). Postoperatively, the difference between measured LL and the ideal LL (LL = 0.54×PI + 27.6) was significant (p = 0.046, 95% CI: 20° ± 9.7°), but not preoperatively (p = 0.55, 95% CI: 6.3° ± 4.8°). Regression analysis suggested that greater changes in LL were associated with changes in quality of life (EQ-5D VAS score), indicating a decline of HQL. However, due to the limited number of patients attributable to the rarity of these tumors, the results did not achieve statistical significance. Discussion: Our study has demonstrated that postoperative sagittal lumbar malalignment is present in patients that did undergo aggressive resection for extradural primary spinal tumors. Reconstructions did not match preoperative and ideal lumbo-pelvic parameters, maybe due to the difficulty to adequately restore lordosis using standard anterior implants in multilevel resections. Alignment failure in turn might be one reason for the high rate of implant failure and reduced life quality in these patients. Reconstruction planning should include SA to avoid complications and further revisions. The possible bias due to reduced sample is noted, an expansion of the database based on a multicenter study might increase the validity of the presented results.

ID: 1961

A097: Evaluating the survivability of renal cell carcinoma spinal metastasis comparing surgical versus non surgical intervention in high grade metastatic spinal cord compression patients: a cohort study

Marzuq Abbas ¹ , Priyanshu Saha ¹ , Charles Taylor ¹ , Zion Hwang ¹ , Liam Rose ¹ , Adnan Sheikh 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: Renal cell carcinoma (RCC) is a significant cause of metastatic spinal cord compression (MSCC). It is radio-resistant and there is the risk of extensive blood loss in surgery. Systemic anti-cancer therapy (SACT) via immunotherapy which may include immune checkpoint modulators (ICI) and vascular endothelial growth factor receptor inhibitors (VEGFR) have taken precedence over chemotherapy. A comparison of the outcomes of surgical vs non-surgical management of patients with MSCC secondary to RCC can further optimise the care pathway for these patients. Materials and Methods: The study retrospectively reviewed 69 RCC patients who presented with MSCC from a database of 2503 patients collected between 2017-2023. Key parameters included mean age at presentation, gender ratio, Charlson Comorbidity Index Score (CCI), revised Tokuhashi Score, ECOG performance status, Frankel Score, survival status, immunotherapy or chemotherapy usage, and mean survival time. Statistical analyses were performed using independent samples tests and Mann-Whitney U tests. Results: Analysed 42 surgical patients and 27 non-surgical patients. Surgical patients had a mean age of 63.8 years and non-surgical patients 64.6 years. Both groups had a median CCI score of 0, with 33.3% of non-surgical patients receiving immunotherapy or chemotherapy in comparison to 16.7% for surgical patients. The mean revised Tokuhashi Score was 7.8 in surgical patients and 6.6 for non-surgical patients (p = 0.015). The pre-MDT Frankel Score was 2.0 for both surgical and non-surgical patients (p = 0.058) and the Median ECOG performance status score was 3.0 for surgical patients and 2.0 for non-surgical patients (p = 0.574). The mean survival time was 8.33 months for surgical patients and 6.97 months for non-surgical patients (p > 0.05). The proportion of deceased patients was 71.4% in the surgical group and 74.1% in the non-surgical group. Conclusion: Surgical patients had a lower mean age and greater mean survival time than non-surgical patients, whilst having a higher mean Tokuhashi score. It is likely that the SACT improves survival times and surgical intervention facilitates this change, whilst Tokuhashi scoring may be inaccurate in patients with survival times less than 12 months. Future studies should aim to include a larger sample size and compare outcomes across different primary tumors to validate these findings and explore potential therapeutic impacts more thoroughly.

ID: 1822

A098: Role of planned colostomy in en bloc sacral sarcoma resection - Impact on surgical site infection and length of stay

Jerome Linkwinstar ¹ , Tho-Vinh Nguyen ² , Fabian Wong ³ , John Afolayan ³ , Ahmed Fadulelmola ³ , Hanny Anwar ³

¹ Royal National Orthopaedic Hospital, Spinal Surgery, London, United Kingdom,

² Royal National Orthopaedic Hospital, London, United Kingdom,

³ Royal National Orthopaedic Hospital, London, United Kingdom

Introduction: Sacrectomy is a surgical procedure performed for the en bloc resection of sarcomas of the sacrum. High rates of surgical site infections (SSIs) have been reported previously. The degree of impact on residual bowel function depends on the level of surgical resection, and thus, patients undergoing low sacrectomy would not routinely require a colostomy. This study aims to determine the impact of having a planned peri-operative colostomy on the rate of SSI in patients undergoing sacrectomy for sarcoma resection, as well as its effect on the length of stay. Material and Methods: A retrospective review was conducted on consecutive patients who underwent sacrectomy at a designated UK tertiary sarcoma specialist orthopaedic hospital between 2011 and 2024. Data collection included patient demographics, tumour types, level of sacrectomy, inclusion of planned colostomy, post-operative surgical site infection, and length of stay. Results: A total of 48 patients were identified over the 13-year period and included in the study. Of these, 31 were males (62%) and 17 were females (38%). Sacrectomy was performed in 26 patients (53%) for conventional chordoma, followed by chondrosarcoma in 7 patients (14%) and osteosarcoma in 1 patient (2%). Twenty-three patients underwent low sacrectomy, while 25 underwent high sacral resection above the level of S3. A total of 24 patients (50%) had a colostomy procedure. Overall, 20 out of 48 patients (42%) developed SSI, of which 14 had either total or partial high sacrectomy. Thirteen patients had a high total sacrectomy with colostomy, 6 of whom (46%) developed SSI, compared to 7 patients (54%) who did not. Among the 23 patients who had low sacrectomy (total or partial), 2 out of 9 with a planned colostomy developed SSI, while 4 out of 14 without colostomy developed SSI. The odds ratio for SSI in low sacrectomy following planned colostomy was 0.71, while the relative risk of SSI with colostomy was 0.78, equating to a 22% risk reduction. Regarding length of stay, patients who developed SSI following low sacrectomy had a mean inpatient stay of 49.3 days, compared to 36.2 days for those who did not develop SSI. Conclusion: Our results suggest an association between the level of sacrectomy and the incidence of surgical site infections (SSIs). High sacrectomy was found to have a higher rate of SSIs, irrespective of whether a colostomy was planned. However, in cases of low sacrectomy, a planned colostomy reduced the risk of SSI by 22%. The study also found a shorter mean length of stay in low sacrectomy cases without SSI.

ID: 1861

A099: En bloc spondylectomy versus separation surgery for spinal metastasis: a systematic review and meta-analysis

Ahmad Kareem Almekkawi ¹ , Ashlesha Bhojane ² , Adeesya Gausper ² , Brandon Edelbach ³ , James P. Caruso ⁴ , Salah Aoun ⁵ , Samuel Goldlust ⁶ , Carlos Bagley ⁷ , Tarek El Ahmadieh ⁸

¹ Saint Luke's Hospital, Neurosurgery, Kansas City, United States,

² University of Missouri - Kansas City, School of Medicine, Kansas City, United States,

³ Loma Linda University, School of Medicine, Loma Linda, United States,

⁴ NYU Langone, Orthopedic Surgery, New York, United States,

⁵ UT Southwestern, Dallas, United States,

⁶ Saint Luke's Cancer Institute, Neurooncology, Kansas City, United States,

⁷ Saint Luke's Hospital, Neurosurgery, Kansas City, United States,

⁸ Loma Linda University, Neurosurgery, Loma Linda, United States

Introduction: Spinal metastases are commonly treated surgically using either en bloc spondylectomy or separation surgery with adjuvant radiotherapy. However, the comparative effectiveness of these approaches remains unclear. Material and Methods: A systematic review and meta-analysis were conducted, searching PubMed, Embase, Scopus, and Web of Science from inception through January 2024. Studies comparing en bloc spondylectomy to separation surgery for metastatic spinal tumors were included. Primary outcomes were overall survival (OS), progression-free survival (PFS), operative blood loss, and post-operative infection rates. Results: Thirty-nine studies (2,967 patients) met inclusion criteria. En bloc spondylectomy (n = 642) was associated with significantly higher intraoperative blood loss compared to separation surgery (n = 2,325) (1595.5 ± 574.8 ml vs 754.5 ± 228.5 ml, p < 0.001). No significant differences were observed in OS (35.7 ± 21.5 vs 26.5 ± 22.2 months, p = 0.307), PFS (22.8 ± 20.2 vs 25.2 ± 28.1 months, p = 0.870), or post-operative infection rates (1.05% vs 1.67%, p = 0.255) between en bloc and separation surgery, respectively. Good clinical outcomes (Frankel grade D or E) were achieved in 93.2% of en bloc cases and 69.8% of separation surgery cases (p = 0.443). Subgroup analyses revealed that kidney metastases had improved PFS with separation surgery (p = 0.012), while thyroid and colorectal metastases had higher recurrence risk with en bloc spondylectomy (p = 0.039 and p = 0.025, respectively). Lumbar spine metastases showed higher recurrence risk with separation surgery (p = 0.038). Conclusion: While en bloc spondylectomy was associated with greater intraoperative blood loss, both techniques demonstrated comparable oncologic and functional outcomes. The choice between these approaches should be individualized based on patient factors, tumor characteristics, and surgical expertise. Further prospective studies are needed to refine patient selection criteria for these procedures in the management of spinal metastases.

OP12: Degenerative Cervical Surgery 2

ID: 1990

A100: Expandable titanium interbody cages with adjustable height and lordosis for anterior cervical discectomy and fusion: a clinical and radiological study

Chibuikem Ikwuegbuenyi ¹ , Hanley Ong ² , Khanathip Jitpakdee ¹ , Jessica Berger ¹ , Minaam Farooq ¹ , Galal Elsayed ¹ , Osama Kashlan 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,

² New York Presbyterian Hospital, Weill Cornell Medicine, Department of Radiology, New York, United States

Introduction: Anterior cervical discectomy and fusion (ACDF) is a well-established surgical procedure for treating degenerative disc disease of the cervical spine, effectively relieving symptoms of myelopathy and radiculopathy. Success in ACDF is often linked to the restoration of cervical and segmental lordosis, as studies show that inadequate correction can result in higher rates of adjacent segmental disease (ASD) and revision surgeries. Despite its benefits, achieving optimal sagittal balance remains challenging with traditional static cages, which can lead to endplate damage and suboptimal lordosis correction. Recent innovations, such as expandable titanium cages with adjustable height and lordosis, offer potential advantages by minimizing endplate violation and enhancing sagittal balance. This study aimed to assess the outcomes of ACDF using an expandable cage, focusing on pain, disability, sagittal alignment restoration, subsidence, fusion rates, and complications. Material and Methods: We conducted a retrospective, single-center study of consecutive patients who underwent ACDF using an expandable titanium cage with adjustable height and lordosis between September 2019 and May 2023. Outcome measures included patient-reported pain and disability scores and radiographic parameters. Fusion was defined as less than 1 mm of motion between spinous processes on dynamic X-rays, while subsidence was identified as a change of more than 2 mm in intervertebral height between immediate post-op and follow-up. Statistical comparisons across time points were performed using the Wilcoxon Signed Rank Test or paired t-test. Logistic regression was used to examine the association between subsidence rate and year of surgery, with significance set at 0.05. All analyses were performed in R Studio. Results: A total of 44 patients (mean age 53 ± 13 years; 52.3% female) with 77 treated levels were analyzed. The most treated level was C5-6 (39%), with most undergoing two-level fusions (61.4%). Median follow-up was 12 months (IQR: 11-13 months). Clinical outcomes showed significant improvements: median NRS-Arm pain decreased from 2 preoperatively to 0 at follow-up (p = 0.025), NRS-Neck pain from 6 to 2 (p < 0.001), and ODI scores improved from a median of 35 to 9 (p = 0.031). Radiographically, cervical lordosis improved from a median of 4.4° preoperatively to 9.0° immediately postoperative (p < 0.001), maintained at follow-up. Segmental lordosis increased from a median of -0.9° to 2.4° postoperatively (p < 0.001). Anterior disc height increased from 4.0 mm to 8.5 mm postoperatively (p < 0.001), remaining significantly higher at follow-up. The fusion rate was 89.6%, with subsidence observed in 20.8% of segments. Subsidence rates significantly decreased from 40% in 2019 to 0% by 2023 (p = 0.044). There were no revision surgeries or neurosurgical complications. Conclusion: This study is the first to evaluate using an expandable titanium cage with adjustable height and lordosis in ACDF procedures. Our findings highlight its effectiveness in correcting cervical sagittal imbalance and increasing disc height and lordosis at the treated level. The results suggest these cages are safe and practical, significantly improving clinical and radiological outcomes. These early results suggest that expandable titanium cages may optimize ACDF procedures and improve patient outcomes.

ID: 293

A101: Anterior versus posterior surgery for degenerative cervical myelopathy: a Canadian spine outcomes research network cost utility analysis

Armaan Malhotra ¹ , Husain Shakil ¹ , Ahmad Essa ² , Nathan Evaniew ³ , Canadian Spine Outcomes Research Network Collaborators ⁴ , Christopher Witiw ¹ , Jefferson Wilson ¹ , Nicolas Dea ⁵

¹ University of Toronto, Toronto, Canada,

² Shamir Medical Center, Zerifin, Israel,

³ University of Calgary, Calgary, Canada,

⁴ Canadian Spine Outcomes Research Network, Toronto, Canada,

⁵ Vancouver General Hospital, Vancouver, Canada

Introduction: Degenerative cervical myelopathy (DCM) is the most common cause of spinal cord dysfunction in adults worldwide. There remains uncertainty regarding the optimal surgical approach for treatment of this disease. We therefore sought to compare anterior to posterior surgery for the treatment of patients with multi-level (2- to 3-level) DCM. Material and Methods: This cost-utility analysis was conducted from the healthcare payer perspective using a lifetime horizon. We conducted a multicenter observational cohort study utilizing prospectively collected data from the Canadian Spine Outcome Research Network (CSORN) and costing data obtained through systematic review and meta-analysis of North American studies. We identified DCM patients enrolled prospectively in CSORN between 2015-2022 undergoing surgery for 2- or 3-level DCM. The study exposure was anterior compared to posterior surgery. The primary outcome was the incremental cost utility ratio (ICUR) of anterior compared to posterior surgical intervention for DCM patients with 2- or 3-level disease. We estimated HRQoL (utility) values measured at 12 months post-surgery using patient reported EQ-5D. Propensity score matching between anterior and posterior surgical groups ensured confounder balance. A random effects meta-analysis was conducted to pool costs derived from systematic review of the literature. These estimates were then used in a time-homogenous Markov state transition model to estimate lifetime costs and utilities associated with each treatment. Results: We included 142 matched DCM patients (71 anterior group, 71 posterior group) after propensity score matching. At 12-months post-surgery, there was no significant difference in EQ-5D between treatment groups (mean difference 0.05, p = 0.055 [t-test]). Meta-analysis of 10 studies found no significant difference in direct cost between the treatment groups with respect to initial in-patient care (mean difference -$4,030.28 USD, p = 0.919 [unpaired t-test]). Lifetime projections found anterior surgery was associated with 0.83 QALYs gained at a cost of $5814.60 USD relative to posterior surgery, on average. The resulting ICUR was $6,979.54/QALY. After Monte-Carlo microsimulation of 10,000 cases, 92.6% of cases favored anterior surgery at 50% the willingness-to-pay threshold, 98.3% at the willingness-to-pay threshold, and 99.1% of cases at 150% the willingness-to-pay threshold, highlighting the dominance of the anterior strategy for lifetime cost-effectiveness. Conclusion: We found an incremental lifetime health-economic benefit to anterior surgery for multi-level DCM in the setting of clinical equipoise. The absolute gains in QALYs were small, suggesting that either surgical approach can be considered depending on patient factors. In a setting of clinical equipoise, anterior surgery is favorable using a lifetime horizon from the perspective of the healthcare payer.

ID: 1309

A102: Prospective comparative study to assess the clinico-radiological adequacy of cord decompression after navigated vs non-navigated laminectomy in cervical spondylotic myelopathy

Jenil Patel ¹ , Ayush Sharma ²

¹ Bombay Hospital and Research Institute, Spine Surgery, Mumbai, India,

² Dr Babasaheb Ambedkar Central Railway Hospital, Spine Surgery, Mumbai, India

Introduction: Cervical laminectomy has traditionally been performed non navigated. Use of navigation has been used and studied mainly for accuracy in pedical screw a. Navigation based approach is likely to improve the accuracy of bony decompression while avoiding facetal breaches. Use of navigation for laminectomy is emerging technique to improve outcome in decompression surgeries. Study Design and Material, Methods: Cervical spondylotic myelopathy treated with navigated and non-navigated laminectomy was included in the study and the data was compared prospectively. Preop and Postop MRI and CT scans were used to assess radiological adequacy of cord decompression with parameters like Total Area (TA), Mean Cord Compression (MCC), and Mean Spinal Cord Compression (MSCC) using Surgimap software, while mJOA and VAS score were used to assess functional outcome. Also to determine usefulness of Navigated cervical laminectomy various parameters like blood loss, operative time, facetal breach were compared. Results: Total 75 patients were included in the analysis. Both navigated and non-navigated procedures showed consistent improvements, with mean VAS scores decreasing from 6.16 to 3.41 and from 5.2 to 2.86, respectively. The mean pre operative mJOA improved from 12.96 to 15.09 post-operatively in Navigated laminectomy, as indicated by a p-value of 0.0001 and from 12.59 pre-operatively to 14.86 post-operatively, with a p-value of 0.0003. Both navigated and non-navigated surgeries showed significantly increased Total Area (TA) post-surgery (“< 0.0001”), with no significant difference between the two. Mean Cord Compression (MCC) percentages decreased significantly (“< 0.0001”) in Navigated approach as compared to non-navigated one. Also, Mean Spinal Cord Compression (MSCC) percentages decreased significantly overall (p-value 0.008), primarily in navigated surgeries. Non-navigated surgeries had longer operative times (144.51 minutes) than navigated (136 minutes), with a significant difference (p-value 0.002). Navigated procedures had a lower incidence of facetal Breach (1 cases) compared to non-navigated (5 cases), with a significant difference (p-value 0.01). Navigated procedures due to limited lateral bony dissection showed lesser mean blood loss of 263.7 ml compared to non-navigated procedures having a mean of 340.9 ml. Conclusion: Navigated surgical approach resulted in significant improvements in Functional and Clinico-radiological parameters post-surgery as compared to non-navigated approach. Use of Navigation exhibited lower rates of complications, better patients’ satisfaction, and lesser chances of future instabilities, mainly because of limited bony excision.

Keywords: Cervical spondylotic myelopathy, Navigation, Laminectomy

ID: 2836

A103: Optimal instrumentation level for long-segment cervical spinal fusions

Marlena Ramanis ¹ , Haley Nadone ¹ , Bryce Picton ¹ , Kyrillos Grace ¹ , Yijie Luo ¹ , Sohaib Hashmi ¹ , Don Park ¹ , Yu-po Lee ¹ , Nitin Bhatia ¹ , Hao-Hua Wu ¹

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

Introduction: Long-segment cervical spinal fusions are a common surgical intervention for managing complex cervical pathologies such as trauma, degenerative conditions, and deformities. One of the key surgical decisions in this procedure is selecting the appropriate distal level for instrumentation, typically ranging from C7 to T3. Fusion to C7 preserves mobility but may lead to junctional complications, while fusions extending to the upper thoracic levels (T1-T3) provide greater biomechanical stability at the cost of increased morbidity. This study aims to evaluate clinical outcomes, complication rates, and biomechanical parameters across different fusion levels (C7-T3) to determine the optimal distal fusion level. Material and Methods: A retrospective cohort study was conducted on 1,034 patients who underwent long-segment cervical spinal fusions between 2010 and 2022. Data points collected for each patient included the number of segments fused (starting and ending segments), sagittal vertical axis (SVA), cervical lordosis (CL), T-score (bone mineral density), pre- and post-operative Neck Disability Index (NDI) and Oswestry Disability Index (ODI), as well as patient demographics and comorbidities (mechanical complications, re-operation, medical record number [MRN], date of birth [DOB], primary insurance, age at surgery, body mass index [BMI], smoking status, diabetes, blood thinner usage, ankylosing spondylitis, diffuse idiopathic skeletal hyperostosis [DISH], pain scores, and infection rates). Results: In this study of 1,034 patients undergoing long-segment cervical spinal fusions, significant improvements were observed in clinical outcomes across the patient cohort. Radiographic assessments showed notable enhancements in sagittal vertical axis (SVA) and cervical lordosis (CL) for distal levels, demonstrating better alignment and stability across groups. Complication rates varied. Overall, patients showed significant improvements in disability scores post-surgery, indicating enhanced neck function. Conclusion: The selection of the distal instrumentation level in long-segment cervical spinal fusions should be guided by a combination of clinical, biomechanical, and patient-specific factors. General synthesis of findings and patterns commonly reported in research indicate fusion to C7 provides greater neck mobility but is associated with higher rates of junctional kyphosis and reoperations. Fusion to T1 offers an ideal balance between stability, sagittal alignment, and complication risk, emerging as the most favorable option in most cases. Fusion to T2/T3 provides the best biomechanical outcomes but at a higher complication cost. The results underscore the importance of tailoring fusion levels to individual patient needs. Further prospective studies are needed to validate these findings and optimize surgical planning for patients requiring long-segment cervical fusions.

ID: 2413

A104: The use of intraoperative neuromonitoring in anterior cervical spine procedures for myelopathy; alert incidence, interventions, and prognostic value

Sydney Rucker ¹ , Gabriella Rivas ² , Jessica Barley ¹ , Jeffrey Korte ¹ , Robert Ravinsky ¹ , James Lawrence ¹

¹ Medical University of South Carolina, Charleston, United States,

² Trident Medical Center, North Charleston, United States

Introduction: The routine use of intraoperative neuromonitoring (IONM) in anterior cervical spine procedures for moderate pathology, particularly degenerative cervical myelopathy, remains controversial. Poorly defined indications for its application and a lack of clear evidence validating protocols for managing intraoperative alerts within this patient population present a critical knowledge gap. Materials and Methods: 109 anterior cervical spine cases from 2021-2024 with continuous IONM were included for retrospective review, excluding revisions and non-degenerative conditions. The incidence of IONM alert was recorded for both myelopathic and non-myelopathy groups. Significant intraoperative signal changes were categorized and assessed for surgical event at time of alert, intraoperative interventions, resolution and duration of alert, and correlation with new post-operative deficit. Patient demographic (age, sex, BMI, race, ethnicity, ASA score) and procedural variables (procedure (ICD-10), surgeon, alternative diagnosis (CPT), number of levels, total monitoring time, intraoperative fluctuations in blood pressure) were assessed for potential confounding effects. Results: Of the 109 cases, 59 included a primary diagnosis of myelopathy and 50 without myelopathy. 26 patients experienced one or more intraoperative alert. The incidence of alert was higher in the myelopathic group (16, 27.1%) compared to the non-myelopathic group (10, 20.0%) (p = 0.385). The most common event at the time of alert for both groups was instrumentation (26%) followed by decompression (24%) and patient positioning (24%). Intraoperative interventions in response to alerts included increasing stimulation parameters, adjusting anesthesia, patient repositioning, and reversal of last surgical maneuver. Alerts in the myelopathic group were more likely to remain unresolved at closure (p = 0.027; OR = 1.62, 95% CI [1.001, 2.62]) and associated with a lower positive predictive value for post-operative deficit. The incidence of alert in both groups was not significantly influenced by fluctuations in blood pressure or any other procedural or demographic variable assessed. Conclusion: The incidence rate of IONM alert was higher in the myelopathic group than non-myelopathic group, but the difference was not statistically significant. Myelopathic patients were significantly more likely to have unresolved alerts at closure; however, unresolved alerts demonstrated limited ability to predict new postoperative deficits.

ID: 62

A105: Machine learning models for predicting dysphonia following anterior cervical discectomy and fusion - A Swedish registry study

Ali Buwaider ¹ , Victor Gabriel El-Hajj ¹ , Anna MacDowall ² , Paul Gerdhem ² , Victor Staartjes ³ , Erik Edström ¹ , Adrian Elmi Terander ¹

¹ Karolinska Institutet, Stockholm, Sweden,

² Uppsala University, Uppsala, Sweden,

³ MICN laboratory, Zurich, Switzerland

Introduction: Dysphonia is one of the more common complications following anterior cervical discectomy and fusion (ACDF). ACDF is the gold standard for treating degenerative cervical spine disorders, and identifying high-risk patients is therefore crucial. This study aimed to evaluate different machine learning models to predict persistent dysphonia after ACDF. Material and Methods: This study analyzed data from the SWESPINE registry on adult patients who underwent elective ACDF between 2006 and 2020, focusing on dysphonia lasting at least one month after surgery. Patients with missing dysphonia data at the one-year follow-up were excluded. Data preprocessing involved one-hot encoding categorical variables, scaling continuous variables, and imputing missing values. Four machine learning models (logistic regression, random forest (RF), gradient boosting, K-nearest neighbor) were employed. The models were trained and tested using an 80:20 data split and 5-fold cross-validation, with performance metrics guiding the selection of the best model for predicting persistent dysphonia. Results: In total, 2,708 were included in the study. Twelve key predictors were identified. Four machine learning models were tested, with the RF model achieving the best performance (AUC = 0.794). The most significant predictors across models included preoperative NDI, number of operated levels, EQ5Dindex, smoking status, and ASA class 1. The RF model, chosen for its superior performance, showed high sensitivity and consistent accuracy, but a low specificity and positive predictive value. Conclusion: In this study, machine learning models were employed to identify predictors of persistent dysphonia following ACDF. Among the models tested, the RF classifier demonstrated superior performance, with an AUC value of 0.790. The RF model identified NDI, EQ5Dindex, and number of fused vertebrae as key variables. These findings underscore the potential of machine learning models in identifying patients at increased risk for dysphonia persisting for more than one month after surgery.

ID: 1923

A106: Cervical pedicle screw placement with patient-specific 3D-printed guides: accuracy and safety in a clinical experience

Nicola Marengo ¹ , Stefano Colonna ¹ , Ayoub Saaid ¹ , Enrico Lo Bue ¹ , Alessandro Pesaresi ¹ , Mario Allevi ¹ , Marco Ajello ¹ , Geert Mahieu ² , Fabio Cofano ¹ , Diego Garbossa ¹

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

² ORTHOCA-AZ Monica Hospital, Orthopedic Surgery, Antwerp, Belgium

Introduction: Cervical pedicle screw (CPS) instrumentation offers significant biomechanical advantages compared to lateral mass or transarticular fixation. Nonetheless, malpositioning complications constitute a relevant concern. Customized patient-specific 3D-printed templates have been developed to improve CPS placement accuracy and safety. The aim of this study is to present our experience with this surgical technique and its accuracy and safety in a clinical setting. Material and Methods: This single-center retrospective observational study of prospectively collected data included patients undergoing CPS fixation surgery using a patient-specific 3D template guide system. In all surgical procedures bilateral or monolateral templates were used. All patients underwent a 3D-volumetric high-resolution CT scan of the cervical spine for preoperative surgical planning. Postoperative CT scans were used to evaluate pedicle perforation, CPS trajectories, and deviations between the planned and the actual screw position. Results: A total of 115 CPS were implanted in 25 patients, with 107 (93.1%) of the screws completely placed inside the pedicle. Cortical breach within 2 mm was observed in 8 (6.9%) cases, with no cases of more severe pedicle infractions or perioperative neurovascular complication. No differences of CPS accuracies were found between each metameric fusion level, and between monolateral or bilateral templates. Mean total deviations were 0.75 mm vertically and 0.51 mm horizontally at the screw entry point, and 0.72 mm vertically and horizontally at the narrowest pedicle point. Mean total sagittal and transverse angular deviations were 2.94° and 3.04°, respectively. Conclusion: Cervical pedicle screw placement using patient-specific guides is safe and accurate, supporting the feasibility of this technique in posterior cervical spine fusion surgery. The significant biomechanical advantages of CPS could allow increased fixation strength over lateral mass screw techniques with potential reduction of fusion area.

ID: 881

A107: Rates of recovery following anterior cervical discectomy and fusion for spondylotic myelopathy vs radiculopathy

Katie Lee ¹ , Arpitha Pamula ¹ , Christopher Lloyd 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 spinal procedure for treating cervical spondylotic myelopathy, radiculopathy, and myeloradiculopathy. While previous studies have compared final outcomes and complication profiles of ACDF procedures, there is limited outcomes data investigating postoperative rates of clinical improvement longitudinally. The purpose of this study was to (1) compare trends in patient reported neck disability index (NDI) scores longitudinally and (2) identify demographic and perioperative characteristics that may influence rate of improvement. Material and Methods: A retrospective analysis was performed from 2019–2023 identifying patients who underwent elective ACDF for cervical spondylotic myelopathy, radiculopathy and myeloradiculopathy. Data collected included patient demographics, surgical diagnosis, perioperative data, surgical complications and reoperations, number of fusion levels, and longitudinal NDI scores. Delta (∆) NDI was calculated as the difference between the current NDI score from the preoperative NDI at each timepoint. A minimal clinically important difference (MCID) of 11 was assumed based on previous literature. Descriptive and inferential statistics were performed. Results: A total of 278 patients (185 Radiculopathy, 39 Myelopathy, 54 Myeloradiculopathy) who underwent ACDF surgeries were included. Average follow-up time was 2.13 years. No cohort differences were observed for age, gender, BMI, ethnicity, or fusion levels. Demographic and perioperative analysis revealed that the radiculopathy cohort had a lower estimated blood loss (39.7 ml vs 43.2 ml, 74.2 ml, p = 0.006), a shorter length of stay (1.9 days vs 2.6 days, 2.2 days, p < 0.0001) compared to myelopathy and myeloradiculopathy cohorts. The myelopathic cohort has a higher percentage of patients using an assistive device (27% vs 7%, 7%, p = 0.001), and a lower percentage of tobacco use (3% vs 11%, 20%, p = 0.045) compared to radiculopathy and myeloradiculopathy cohorts. At 6 weeks postoperatively, more patients achieve improvement exceeding MCID in the myelopathy cohort (82%) than the radiculopathy (50%) and myeloradiculopathy (44%) cohorts (p = 0.029). This difference in recovery subsides, and all cohorts achieve similar long-term recovery by 1 year (Myelopathy: 72%, Radiculopathy: 80%, Myeloradiculopathy: 78%, p = 0.523), with similar improvement in ∆NDI scores (Myelopathy: -17.8, Radiculopathy: -23.7, Myeloradiculopathy: -23.3, p = 0.087). MCID analysis was also performed comparing single-level and multi-level procedures with no statistical significance found between both groups at all timepoints. At 1 year, 74% of the single-level cohort achieved MCID compared to 81% of the multi-level cohort (p = 0.214). No demographic or perioperative factor was found to influence ∆NDI scores based on multivariate linear regression analysis. Conclusion: Patients undergoing ACDF for cervical spondylotic myelopathy, radiculopathy and myeloradiculopathy achieve similar long term clinical improvement exceeding MCID. Myelopathic patients however have a more rapid improvement, and a greater proportion achieve MCID by 6 weeks post-operatively compared to patients with radiculopathy or myeloradiculopathy. This difference in recovery rate is not explained by number of fusion levels, demographic or perioperative factors based on multivariate analysis. Our results have potential to guide providers in counseling patients, establishing realistic recovery timelines, and managing postoperative expectations.

ID: 1369

A108: Posterior only or single-stage combined anterior and posterior approach decompression for treating multilevel cervical spondylotic myelopathy with occupation rate more than 50%: a prospective controlled study with a minimum 6-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: Multilevel cervical spondylotic myelopathy (MCSM) is a common disorder caused by degenerative changes. Surgical decompression by anterior, posterior or combined approach should be considered with neurological deficits. Posterior approach by laminoplasty may be a preferred method for MCSM.However,when occupation rate more than 50%, inadequate decompression by laminoplasty only may result in unsatisfactory neurofunctional improvement. Then one-stage combined anterior and posterior approach would be a theoretically better strategy with adequate decompression. However, for MCSM with occupation rate exceeds 50%, optimal strategy remains controversial. This prospective study was to compare clinical and radiological outcomes between laminoplasty only approach and single-stage laminoplasty combined with anterior decompression approach for MCSM when occupation rate more than 50%. Material and Methods: The study enrolled 80 MCSM patients with occupation rate more than 50% from 2014 to 20017 in our department. Among these patients, 40 underwent single-stage combined anterior decompression and laminoplasty (combined group) and 40 underwent laminoplasty only (posterior group). The clinical outcome was evaluated by VAS and mJOA. The radiological outcome was evaluated with cervical alignment and ROM. Operation time, blood loss, complication and reoperation rate were recorded and compared between the two groups. Results: In terms of age and sex, differences were not detected between two groups. The mean follow-up duration was 78.4 ± 2.2 months in combined group and 79.6 ± 2.0 months in posterior group (p = 0.766). The VAS scores in posterior group decreased from an average of 3.8 ± 1.0 preoperative to 1.2 ± 0.5 points at last follow-up, while decreased from 3.9 ± 1.1 to 1.1 ± 0.4 in combined group, without significant difference. The mJOA scores increased from an average of 9.8 ± 1.0 to 13.4 ± 1.2 at last follow-up in posterior group, while increased from 9.6 ± 0.9 to 14.5 ± 0.9 in combined group, with significant difference at last follow-up (p = 0.043). Interestingly, when evaluated upper limb function improvement by mJOA, significant difference was detected with 2.1 ± 0.4 in posterior group and 3.0 ± 0.5 in combined group (p = 0.037), but not for lower limb function score (p = 0.599). The cervical alignment and ROM showed no difference between two groups. The operation time and blood loss was more in combined group. Minor complications occurred in 6 patients (15%) in posterior group and in 9 patients (22.5%) in combined group. The reoperation rate in posterior group was 10%, including residual symptoms in 3 and new onset symptom in 1, while 2.5% in combined group for adjacent-level disease. Satisfaction survey showed that 40% of patients in posterior group seen to undergo combined anterior and posterior approach at last follow-up. Conclusion: Although with relatively more surgical trauma, for MCSM with occupation rate exceed 50%, one-stage combined anterior and posterior approach may provide better improvement of neurological function, especially for upper limb function. The reoperation for residual symptoms should be an ignored problem when occupation rate more than 50%.

OP13: Cervical Trauma Surgical 1

ID: 2334

A109: Traumatic posterior atlantoaxial dislocation without an associated fracture: a PRISMA-compliant case-based systematic review and meta-analysis

Mahmoud Fouad Ibrahim ¹ , Ahmed Shawky Abdelgawaad ¹ , Amr Hatem ¹ , Essam Mohammed El-Morshidy ¹ , Mohamed El-Meshwawy ¹ , Mohammad El-Sharkawi ¹

¹ Assiut University Hospitals, Department of Orthopedic and Trauma Surgery, Assiut, Egypt

Introduction: The atlantoaxial joint has a wide range of motion, contributing to more than 50% of cervical spine rotation. Anterior atlantoaxial dislocation usually results from disruption of the transverse ligament or deformity of the odontoid process. Posterior atlantoaxial dislocation is primarily associated with fracture of the odontoid process or the anterior arch of C1. Therefore, traumatic posterior atlantoaxial dislocation (TPAD) without an associated fracture is a rare injury. The first reported case of this injury was presented by Haralson and Boyd in 1969. Since then, few cases have been documented in the literature. Nevertheless, the pathogenesis and optimal management for these uncommon injuries remains topics of debate. This PRISMA-compliant case-based systematic review and meta-analysis aimed to comprehensively explore TPAD, covering clinical presentation, diagnosis, treatment, and clinical and radiological outcomes. Material and Methods: Initially, we presented a case of TPAD without an associated fracture. Then we systematically searched electronic databases (Scopus, PubMed and Web of Science) with no language restrictions, from inception through October 2023 to identify case reports of patients with TPAD without an associated fracture. Furthermore, we manually examined the references of the included articles. The search terms used were (((((((atlantoaxial) OR (atlanto-axial)) OR (atlanto axial)) OR (atlas)) OR (axis)) OR (c1-c2)) AND ((dislocation) OR (luxation))) AND ((((traumatic) OR (posttraumatic)) OR (post-traumatic)) OR (post traumatic)). We included patients with TPAD who did not have any associated fractures of the odontoid process or the C1 arch. Cases with dislocation due to congenital anomalies or inflammatory process were excluded. Two researchers independently extracted the data, using a standardized data extraction form. The extracted data included: author, year of publication, country, gender, age, mechanism of injury, associated injuries, loss of consciousness, facial injury, neurological deficit, neurological recovery, method of reduction, time from injury to the first attempt of closed reduction, method of fixation, fusion, and follow up period. Results: 31 cases of TPAD without an associated fracture were included. The majority (81%) were males, and traffic accidents were the leading cause (87%). Initially, 52% of the cases did not exhibit any neurological deficits. Regarding treatment approaches, 23% were managed through closed reduction alone, 32% required fusion following closed reduction, and 45% underwent open reduction and fusion. A time delay exceeding 7.5 days significantly increased the risk of closed reduction failure (OR 56.463; p = .011). Conclusion: TPAD without an associated fracture is a challenging spinal injury. Patients often present without neurological deficits. Based on the evidence, this review identified key management strategies. It is crucial to promptly perform closed reduction under C-arm while monitoring neurological status once the patient is hemodynamically stable. Surgical fusion is indicated for cases with MRI-confirmed transverse ligament rupture or residual instability. If closed reduction fails, open reduction and fusion should be carried out. Posterior C1-C2 screws fixation is the preferred fusion technique, providing high levels of safety and biomechanical stability.

ID: 2065

A110: Dens fractures and traumatic posterior atlantoaxial subluxation: mechanism of injury, concomitant injuries, complications, and mortality

Emily Adams ¹ , Allen Zou ² , Leila Erbay ² , Andrew Li ² , Antonio Lobao ¹ , Daniel Chen ² , Mohamed Yousef ¹ , Robert Shepard ² , Raj Gala ¹ , Michael Stauff ¹

¹ UMass Memorial Medical Center, Department of Orthopedics and Physical Rehabilitation, Worcester, United States,

² UMass Chan Medical School, Worcester, United States

Introduction: Many patients with dens fractures are at risk for traumatic posterior atlantoaxial subluxation (TPAS). This study analyzes rates of TPAS in patients with dens fractures and the associated morbidity/mortality of this injury pattern compared to dens fracture patients without TPAS. We hypothesize that patients with dens fractures and TPAS will have higher rates of neurologic injury and morbidity/mortality than non-TPAS patients. Material and Methods: 201 adult patients with acute dens fractures from 2017 - 2023 were retrospectively reviewed and sorted by TPAS (n = 68) and non-TPAS (n = 133) injuries. CTs, CTAs, and MRIs from the time of injury were reviewed and fractures were identified using AO Upper Cervical and Subaxial classification systems. Demographics, mechanism of injury (MOI), injury details, and complications were also collected. Results: TPAS patients were significantly older than non-TPAS patients (TPAS 82.5, non-TPAS 70.7; p < 0.001). Charlson comorbidity index, body mass index, pre-injury ambulation rates, Glasgow Coma Scale, Injury Severity Score, and length of stay were not significantly different between groups. The MOI differed significantly between groups (p = 0.027). Ground level fall (GLF) and fall from height (FFH) were the most common MOI for TPAS (GLF 60.3%, FFH 30.9%) and non-TPAS (GLF 50.4%, FFH 21.8%). Non-TPAS patients were more often involved in motor vehicle collisions (MVC 18.0%) or were pedestrian struck (PS 3.0%). While concomitant limb or head injury rates were not significantly different between groups, TPAS patients saw greater rates of concomitant spinal cord injury (SCI) (TPAS 14.7%, non-TPAS 4.5%; p = 0.012) and lower rates of visceral injuries (TPAS 13.2%, non-TPAS 21.1%; p = 0.001) and C4 fractures (TPAS 0%, non-TPAS 6.0%; p = 0.039) than non-TPAS patients. Dens fracture morphology was significantly different between groups (p < 0.0001). Within the TPAS group, 98.5% of patients had either a type II (88.2%) or III (10.3%) dens fracture; 97.7% of non-TPAS patients had a type II (40.6%) or III (57.1%) fracture. TPAS patients had a higher rate of type II dens fractures, versus non-TPAS patients who had a higher rate of type III fractures. Surgical treatment (TPAS 14.7%, non-TPAS 6.0%, p = 0.041) and death within 30 days of initial injury (TPAS 13.2%, non-TPAS 11.3%, p = 0.002) were both significantly different between groups. Conclusion: Among dens fracture patients, TPAS patients experienced significantly higher rates of 30-day mortality in addition to greater rates of concomitant SCI than non-TPAS patients. TPAS patients also presented with a higher rate of type II dens fractures than non-TPAS patients. Given the displacement of the atlantoaxial segment and higher rate of type II fracture morphology, we believe this type of injury will more commonly require surgical treatment. We also think the patient with a type II dens fracture and TPAS represents a special subset of dens fractures that have a higher risk of neurologic injury than is typical for all other dens fractures.

ID: 1558

A111: The effect of early vs late surgery on clinical outcome in patients with central cord syndrome

Rebecca Irvine ¹ , Ahmed Ibrahim ¹ , Kevin Tsang ¹

¹ Imperial College London, London, United Kingdom

Introduction: Traumatic spinal cord injury (TSCI) constitutes a considerable proportion of the injury burden within the United Kingdom (UK). Central cord syndrome (CCS) is a common cause of incomplete TSCI, often presenting in elderly patients with neck hyper-extension. A meta-analysis of animal studies found that early decompressive surgery improved outcomes by 35% for patients with TSCI. However, the effect of early surgery in the clinical setting for patients with CCS remains unclear. In this study, we aim to investigate whether early surgery improves neurological outcomes in a UK trauma centre. Material and Methods: A retrospective cohort study was conducted of adults admitted with CCS to a level 1 major trauma centre between 2016 and 2019. The Trauma Audit and Research Network database was used to identify 1621 patients admitted with spinal injury. Children, patients without surgical intervention, and patients without spinal cord involvement were excluded. Electronic health records were then used to identify patients with CCS. The primary outcome was the timing of surgery on admission American Spinal Injury Association (ASIA) Impairment Scale. Results: 37 patients with CCS were included, of which 75.7% were male. The mean age of patients was 66.8 years old, and the most common aetiology of injury was falls (91.9% of patients). 35.1% of patients had an improvement in ASIA grade from admission to discharge. Overall, patients undertaking surgery within 24 hours from admission had a statistically significant higher improvement in ASIA grade (p = 0.0078). Conclusion: The first 24 hours from admission represent a crucial timeframe to undergo early decompressive surgery, for optimal clinical outcome in patients with CCS. Further investigation would be required to determine patient-specific neurosurgical factors, such as local pressure on the spinal cord, that could determine the urgency of surgical decompression.

ID: 2333

A112: Survival rates after cervical spine fractures in patients with ankylosing spinal disorders: a matched comparison of surgical and non-surgical managements

Josefin Åkerstedt ¹ , Ali Buwaider ² , Victor Gabriel El-Hajj ² , Johan Wanman ¹ , Henrik Frisk ² , Simon Blixt ³ , Anna MacDowall ⁴ , Erik Edström ⁵ , Adrian Elmi Terander ^4,5 , Anastasios Charalampidis ³

¹ Umeå University, Department of Diagnostics and Intervention, Orthopedics, Umeå, Sweden,

² Karolinska Institutet, Department of Clinical Neuroscience, Stockholm, Sweden,

³ Karolinska University Hospital, Department of Reconstructive Orthopedics, Stockholm, Sweden,

⁴ Uppsala Academic Hospital, Department of Surgical Sciences, Uppsala, Sweden,

⁵ Löwenströmska Hospital, Capio Spine Center Stockholm Spine Center, Stockholm, Sweden

Introduction: Ankylosing spinal disorders (ASD) increase the risk of unstable cervical spine fractures, especially among the elderly with high mortality rates. Surgery is recommended but challenging due to deformation and loss of anatomical landmarks. Non-surgical options may often fail yet are still chosen in many cases. However, it is unclear if non-surgical treatment is less effective in patients with intact neurological function. This study aimed to compare survival rates between surgical and non-surgical treatments of ASD-related cervical fractures in matched cohorts. Methods: The study analyzed data from the Swedish Fracture Registry (SFR) on adult patients treated for ASD-related cervical spine fractures between January 2013 and December 2021. Preoperative variables included age, sex, trauma type, neurological function, fracture morphology, and treatment method. Surgically treated patients underwent fracture fixation, while non-surgically treated patients received rigid collars. Propensity score matching was conducted to compare outcomes between treatment groups, ensuring balanced comparison groups regarding age, sex, type of trauma, time from injury to admission, fracture type, level of injury, and neurological function. Results: In total, 357 adult patients with ASD-related cervical spine fractures were analyzed. Among them, 186 were treated surgically and 171 non-surgically. Treatment failure and conversion so surgical treatment was seen in 3.4% of the non-surgically treated patients. Most patients were male (80%), with a median age of 75 years. Fractures were mainly caused by low-energy trauma (69%). Most patients (92%) were ambulatory (Frankel grade D or E). In the unmatched analysis, surgically treated patients had significantly lower mortality rates (17%, p < 0.001), but after matching, there were no significant differences in survival between the two groups (p = 0.810). Multivariable logistic regression analysis identified high age as the only predictor for 30-day mortality (OR 1.14 [95% CI 1.09 - 1.22], p < 0.001). Conclusion: Patients with subaxial ASD-fractures who are neurologically intact may be managed successfully both using surgical and non-surgical approaches. Individualized management strategies, with a global assessment of risks, are advised. In addition, patients should be carefully monitored for early identification of treatment failure.

ID: 650

A113: Surgical delay predicts unplanned reoperation and increased length of stay following anterior fixation of odontoid fractures

Austen Katz ¹ , Ryan Hoang ² , Wyatt David ¹ , Junho Song ³ , Timothy Hoang ³ , Shane Burch ¹

¹ University of California, San Francisco, Orthopaedic Surgery, San Francisco, United States,

² UC Irvine School of Medicine, Irvine, United States,

³ Mount Sinai Department or Orthopedic Surgery, New York, United States

Introduction: Surgical management of odontoid fractures is utilized to promote higher fusion rates, reduce medical complications, and limit mortality. Operative indications are narrow and based on age, overall comorbidities, and fracture pattern, thereby allowing for a homogeneous research population. Delay in surgical management of operative odontoid fractures after hospital admission, however, may be associated with greater rates of adverse events and length of stay. Prior research has identified delay in surgery for patients undergoing elective ACDF as a risk factor for major adverse events, mortality, and hospital stay. There currently is no literature evaluating delay in surgery as a risk factor for poor outcomes following anterior surgical management of odontoid fractures. Material and Methods: A retrospective observational study was conducted on patients who underwent anterior fixation for an odontoid fracture from 2013 to 2022, utilizing the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP). Eligibility for inclusion was determined by age > 18 years and CPT codes 22318 and 22319. Patients with preoperative sepsis or cancer were excluded. Outcomes including length of stay, wound infection, mortality, reoperation, and readmission were compared between cohorts. Prolonged time between hospital admission and surgery, defined as surgical delay > 48 hours based on previous literature, was assessed as a predictor of clinical outcomes. Multivariable Poisson regression adjusted for demographics and comorbidities, including age and ASA-class was used to determine if surgical delay was predictive of complications, with Wald chi-square (χ2) employed to quantify the contribution of each variable to the logistic regression model. Results: There were 265 patients identified, 32% (85) of which had a surgical delay > 48 hours. Mean age was 71.5 years. Patients in the surgical delay group had greater rates of ASA-class > 3 (42.1% vs 34.3%, p = 0.049). Age, sex, race, BMI, and other medical comorbidities were statistically similar at baseline between groups. In univariate analysis, surgical delay was associated with greater length of stay (8.2 vs 4.5 days, p = 0.012) and unplanned reoperation (11.8% vs 3.3%, p = 0.011), and trended toward association with readmission (9.4% vs 3.3%, p = 0.072). Surgical delay did not predict mortality (4.7% vs 3.9%, p = 0.749). After adjusting for significant covariates, multivariate Poisson regression demonstrated that surgical delay independently predicted length of stay (χ2 = 257.75, p < 0.001) and unplanned reoperation (χ2 = 5.24, p < 0.001), but not readmission (χ2 = 3.21, p = 0.073). Conclusion: At baseline, patient demographic and comorbidity characteristics were similar in the delay and non-delay groups, with the exception ASA-class > 3. Rates of readmission, length of stay, and reoperation were statistically greater in the surgical delay cohort, while the remaining complications, including mortality, did not differ significantly. When adjusting for significant covariates in the regression model, surgical delay independently predicted length of stay and reoperation. Due to limitations with the NSQIP database, it is not possible to conclude if surgical delay itself is due to systematic factors such as lack of operating room availability or is a result of more medically complex patients requiring optimization. These results suggest that patients with delay to surgery should be identified and targeted to minimize risk of adverse outcomes.

ID: 2084

A114: Disproportionate use of computed tomography angiography in traumatic cervical spine fracture patient population

Antonio Lobao ¹ , Leila Erbay ² , Andrew Li ² , Allen Zou ² , Emily Adams ¹ , Daniel Chen ² , Mohamed Yousef ¹ , Robert Shepard ² , Raj Gala ¹ , Michael Stauff ¹

¹ UMass Memorial Medical Center, Department of Orthopedics and Physical Rehabilitation, Worcester, United States,

² UMass Chan Medical School, Worcester, United States

Introduction: Computed Tomography Angiography (CTA) is often ordered to evaluate for vertebral artery injuries (VAI) in traumatic cervical spine fracture (CSFX) patients. This study analyzes CTA ordering patterns and observed risk factors for acute VAIs. We hypothesize that there are discrepancies in the injury profile of patients receiving CTAs versus those who suffer VAI. Material and Methods: Medical records of 930 adult patients with traumatic CSFXs from 2017-2023 were retrospectively reviewed. We identified patients with CTAs ordered (CTA) versus no CTAs ordered (non-CTA); CTA was subdivided between patients with acute VAI (VAI-positive) and without VAI (VAI-negative). Demographics, mechanism of injury (MOI), AO Spine Upper Cervical and Subaxial classifications, and injury details were collected and analyzed using Student’s t-tests and chi-squared tests. Results: CTA consisted of 674 (72.5%) patients; 102 were VAI-positive (15.1% of CTA). There were no significant differences in demographics between CTA and non-CTA, however VAI was associated with male sex (73.5% versus 56.1%, p < 0.001). There were no significant differences in other demographic factors between CTA subgroups. CTAs were associated with higher rates of upper CSFXs (62.1% versus 33.2%, p < 0.001), however there was no association with VAI for upper CSFXs. Subaxial CSFXs were more likely in VAI-positive patients (67.6% versus 54.5%, p = 0.014). CTAs were more often ordered for non-displaced upper CSFXs and tension band injuries (OR = 2.53, p = 0.013), whereas VAI-positive patients were more likely to suffer displaced or dislocated subaxial CSFXs (OR = 2.81, p < 0.001). Floating lateral mass injuries (2.5% versus 0.4%, p = 0.035) and cervical ligamentous injuries (45.5% versus 37.9%, p= 0.035) were more likely to receive CTA; there was no significant difference between CTA subgroups. Rates of subluxed, perched, or dislocated facet injuries were greater in VAI-positive patients (18.6% versus 8.2%, p = 0.001). Upper CSFXs that were neurologically intact were more likely to receive CTA (48.1% versus 24.2%, p < 0.001) and subaxial CSFXs that were neurologically intact were less likely to have VAI (25.5% versus 37.9%, p = 0.016). Although there was no significant difference in spinal cord injury (SCI) rates between CTA and non-CTA patients, VAI-positive patients experienced higher SCI rates (21.6% versus 10.3%, p = 0.019). There was no significant difference in MOI between CTA and non-CTA. VAI-positive patients were more likely to be injured by motorcycle collisions (MCC; OR = 2.48, p = 0.049) and gunshot wounds (GSW; OR = 11.63, p = 0.006) than VAI-negative patients. Conclusion: CTA orders were disproportionately higher for neurologically intact patients with non-displaced upper cervical spine fractures and concomitant ligamentous and lateral mass injuries. VAIs are more likely to present in male patients, injured by MCC or GSW, who suffer dislocated subaxial cervical spine fractures, severe facet injuries, SCIs, and neurological deficit. Providers should consider fracture severity and location, patient sex, neurological status, and MOI when ordering CTAs to rule out VAI. A thorough algorithm for ordering CTAs can encourage more efficient allocation of limited imaging resources for other at-risk patient populations.

ID: 308

A115: Predictive value of scoring systems in timing of surgical intervention for acute traumatic central cord syndrome: a retrospective cohort study in a multi-ethnic Asian population

A Aravin Kumar ¹ , Linda Lim Huiling ¹ , Zhiquan Damian Lee ¹ , Lester Lee ¹ , Dinesh Shree Kumar ² , Robin Pillay ¹ , Ji Min Ling ¹

¹ National Neuroscience Institute, Department of Neurosurgery, Singapore, Singapore,

² Changi General Hospital, Department of Orthopaedic Surgery, Singapore, Singapore

Introduction: Acute traumatic central cord syndrome (ATCCS) is the most prevalent form of incomplete spinal cord injury. Recent recommendations advocate for early surgical intervention to enhance neurological outcomes. However, these recommendations are predominantly based on North American studies, raising concerns about their applicability to Asian populations. Scoring systems such as the Central Cord Score (CCScore), Acute Traumatic Central Cord Syndrome Score (ATCCSS), and Subaxial AO Spine Injury Score (Subaxial AOSIS) are increasingly used to guide treatment and improve patient outcomes. This study aimed to evaluate the predictive value of these scores in relation to functional and neurological improvements, stratified by surgical timing - early (within 24 hours) versus late (more than 24 hours). Material and Methods: A retrospective cohort study was conducted at tertiary centres in Singapore from 2010 to 2023. Adult patients diagnosed with ATCCS were included, while those with other neurological conditions were excluded. The ATCCSS, CCScore, and Subaxial AOSIS were calculated for all patients, who were grouped by surgical timing. Key outcomes included meaningful motor recovery at 12 months (≥ 20% improvement in the American Spinal Injury Association Motor Score), improvement in the Functional Independence Measure (FIM), and modified Japanese Orthopaedic Association (mJOA) scores. Area under the curve (AUC) analysis was used to assess the predictive ability of each score for distinguishing between early and late surgery, with optimal cutoffs identified using Youden's J statistic. Subgroup analyses explored the influence of surgical timing on outcomes and score concordance. Results: Eighty patients were included, with a mean age of 66.9 years (SD 11.4); 85% were male, and 67.5% underwent surgical management. AUC analysis demonstrated that the CCScore had the highest predictive value for distinguishing early from late surgery (AUC = 0.85, 95% CI: 0.72-0.95), followed by ATCCSS (AUC = 0.82, 95% CI: 0.69-0.92) and Subaxial AOSIS (AUC = 0.73, 95% CI: 0.55-0.88). Optimal cutoffs for early surgery were 3 for ATCCSS, 11 for CCScore, and 14 for Subaxial AOSIS. Subgroup analysis showed that early surgery patients had significantly higher ATCCSS (mean 3.4, SD 0.74) and CCScore (mean 11.5, SD 2.07) compared to late surgery patients (mean ATCCSS 2.38, SD 0.85; mean CCScore 8.23, SD 2.36), with p-values < 0.01 for both. While early surgery was associated with higher meaningful motor recovery at 12 months (93%, SD 25.8% vs. 79%, SD 40.9%), this was not statistically significant (p = 0.15). Early surgery was linked to a significantly lower FIM improvement rate (13%, SD 35.2% vs. 41%, SD 49.8%, p = 0.028). mJOA improvement was similar between the two groups (87.0% vs. 87.2%, p = 0.96). Concordance analysis showed that early surgery patients had higher concordance with ATCCSS (93.3% vs. 66.7%, p = 0.012) and slightly higher concordance with CCScore (86.7% vs. 66.7%, p = 0.10). Conclusion: Both the CCScore and ATCCSS were strong predictors of early surgical intervention. ATCCSS, with a cutoff of 3, was particularly useful in guiding early treatment. Together with CCScore and Subaxial AOSIS, these scores provide valuable tools for optimizing surgical timing and improving outcomes across diverse populations.

ID: 1615

A116: Predictors of occipito-cervical fusion and halo immobilization in the setting of type 3 occipital condyle fractures

Matthew Kreinbrink ¹ , Parantap Patel ¹ , Ziam Khan ¹ , Adedayo Olaniran ¹ , Ovais Hasan ¹ , Emre Derin ¹ , Timothy Chryssikos ¹

¹ University of Maryland School of Medicine, Department of Neurosurgery, Baltimore, United States

Introduction: Occipital condyle fractures (OCFs) often occur in the setting of multi-trauma, with reported prevalence rates ranging from 4% to 16%. Approximately 23% of OCFs are type III, a subtype with potential instability due to disruption of the alar ligament insertion site. Current management strategies include hard collar immobilization, Halo immobilization, and occipital-cervical fusion. This study assessed predictors of treatment selection and reports outcomes of patients managed conservatively with hard cervical collar only. Material and Methods: A retrospective analysis of type III OCF was performed over an 8-year period (2016-2024) at a single Level 1 Trauma Center. Patients were identified by querying an institutional database for relevant ICD-10 codes. All patients and their respective imaging studies were screened to verify diagnosis of type III OCF. Patients with type I and type II OCF were excluded. Demographic, clinical, surgical, and radiographic data were collected. Univariate and multivariate analyses were performed to assess for significant associations with treatment selection. Results: One-hundred-twenty-five patients with confirmed type III OCF were identified. Median age was 41 [17-84], and 69.6% of patients were male. Mean GCS was 11.1 and mean ISS was 26.2. Among the 63 patients who underwent MRI, 15 (23.8%) had additional evidence of direct injury to the alar ligament itself. One-hundred-seven patients (85.6%) were managed with collar only, including ten patients with evidence of direct alar ligament injury. Head-to-head comparison of collar versus occipital-cervical fusion or HALO immobilization revealed that high energy injury mechanism (p < 0.001), bilateral Type III OCF (p < 0.001), direct alar ligament injury (p < 0.001), and additional fracture or dissociation between C0-C1-C2 [including atlanto-occipital dissociation (AOD) and atlanto-axial dissociation (AAD)] (p = 0.03) were associated with selection of occipital-cervical fusion surgery or halo immobilization rather than collar. A multivariate model showed that admission GCS was an independent and significant predictor for selection of conservative (collar) versus more invasive (surgery or HALO) treatment (OR 1.28 [95% CI 1.13-1.46]). Six patients underwent occipital-cervical fusion. Indication for surgery was AOD in three patients, AOD and AAD in one patient, and AOD and AAD with spinal cord injury in two patients. Two patients underwent Halo immobilization, and the primary indication in each was AOD. Among patients managed with collar only, there were no cases of worsening C0-C1 subluxation/subsidence on CT at 6-week follow-up (65.6%). No patient treated with collar only had delayed occipital-cervical fusion surgery at 6-month follow-up (39.3% of patients) or 12-month follow-up (18.0% of patients). Conclusion: There was a significant association between admission GCS and management strategy for Type III OCF. Among patients treated with collar only, there was no C0-C1 subluxation/subsidence at short-interval follow-up and no patient had delayed surgery at 6 or 12 months. Patients who were treated with occipital-cervical fusion or Halo immobilization had additional injuries between C0-C1-C2. Direct injury to the alar ligament itself in the setting of Type III OCF did not preclude successful treatment with collar only.

ID: 2301

A117: Stable central cord syndrome (CCS-S): clinical features of a distinct phenotype of central cord syndrome

Karlo Pedro ¹ , Mohammed Ali Alvi ¹ , Michael Fehlings ^1,2

¹ University of Toronto, Toronto, Canada,

² University Health Network, Toronto, Canada

Introduction: The outcomes of central cord syndrome (CCS) are highly variable, in part owing to the heterogeneous patient phenotypes this term encompasses. CCS may result from high-energy trauma (e.g., motor vehicle accidents) producing fractures, dislocations, and/or disc herniations, or alternatively, from low-energy trauma (e.g., falls) in patients with pre-existing cervical spondylosis and stenosis, without bony column injury. However, a direct comparison of outcomes in these two distinct patient groups, both with CCS, is lacking. In the current paper, the authors introduce the terms ‘central cord syndrome-stable’ (CCS-S) and ‘central cord syndrome-fracture’ (CCS-F) to establish a stratified framework to address the inherent heterogeneity within the CCS population. Materials and Methods: We identified cases of cervical incomplete SCI from four major prospective, multicenter studies conducted between December 1991 and March 2017. CCS patients were identified based on a minimum 5-point difference between the lower extremity motor score (LEMS) and upper extremity motor strength (LEMS – UEMS ≥ 5). These patients were then stratified into CCS-F and CCS-S groups based on the absence or presence of a fracture, respectively. Initial injury severity and neurological recovery were assessed using LEMS, UEMS, and ASIA total motor score (AMS), while functional outcomes were evaluated using the functional independence measure (FIM) score. We analyzed change in outcomes at one year, including the proportion of patients achieving the minimum clinically important difference (MCID), using univariate statistics. A subgroup analysis, adjusted by propensity score matching, was conducted to compare surgically treated CCS-S patients. Independent predictors of neurological and functional outcomes were identified through multivariable regression analysis. Results: Out of the 2,452 SCI patients in the combined dataset, a total of 268 patients were treated for CCS. Among these, 124 (46%) patients were classified as CCS-S. This group was significantly older (mean age: 49.74 vs 44.06 years, p = 0.01) with predominantly male sex compared to the CCS-F cohort. Falls were the primary cause of injury in the CCS-S group, whereas vehicular crashes were the leading cause in the CCS-F cohort. Despite lower baseline functional motor scores (FIM Motor. 52.52 vs 62.28, p = 0.01), CCS-S patients demonstrated greater improvement in UEMS [Mean Difference (MD) = 3.61, p = 0.03], FIM motor (MD = 7.07, p = 0.02) and FIM total scores (MD = 7.07, p = 0.03) compared to their CCS-F counterparts. Patients undergoing surgery achieved significantly greater functional independence at one year, with a higher proportion reaching the FIM Motor MCID (67.6% vs 35.7%, p = 0.004). CCS-S class emerged as an independent predictor of neurological and functional improvement in CCS patients at one-year follow up. Conclusion: CCS-S represents a distinct phenotype within the CCS patient population, demonstrating greater upper motor and functional recovery potential compared to the CCS-F cohort. Surgical intervention in this group was associated with superior functional outcomes at one year. Adopting uniform terminology for CCS-S will facilitate the implementation of treatment algorithms and help address the heterogeneity of this condition.

OP14: Surgical Complications

ID: 2493

A118: Using machine learning to predict pseudarthrosis following corrective surgery in adult spinal deformity patients

Ted Shi ¹ , Varun Arvind ¹ , Alexander Tward ¹ , Daniel Ortega ¹ , Hamzah Abbas ¹ , Justin Reyes ¹ , Roy Miller ¹ , Cole Morrissette ¹ , Yong Shen ¹ , Mark M. Herbert 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: Pseudarthrosis of the spine is a poorly understood condition and remains difficult to predict despite extensive literature regarding risk factors. Machine learning (ML) has the potential to aid in the clinical risk assessment for pseudarthrosis, although no clear ML tools currently exist in clinical practice. Materials and Methods: We retrospectively reviewed 336 adult patients undergoing spinal deformity surgery. More than 100 variables were included (medical history, operative factors, labs, preoperative x-rays). Patients were randomly separated into training (70%) and testing (30%) cohorts. A preoperative risk calculator to predict pseudarthrosis was developed using a stepwise ML approach. First, a random forest classifier model was trained on all variables. Then, Boruta, a feature selection algorithm, selected for the most important variables. Finally, a multivariate logistic regression model was trained and evaluated on the variables selected by Boruta. Model performances were evaluated using predictive performance metrics such as accuracy, sensitivity, specificity, and area under the receiver operating curve (AUROC) score. Comparative statistics (p < 0.05) were also performed to evaluate differences between union and nonunion cohorts. Analysis was performed using scikit-learn (v.1.5.1) in Python (v.3.9.5). Results: 45 of the 336 (13.4%) of patients were found to have developed pseudarthrosis. Traditional comparative statistics determined that BMI, age, baseline Oswestry Disability Index (ODI) score, number of rods, amount of bone morphogenetic protein (BMP), decompression (yes/no), posterior cranial vertical line (PCVL) to sacrum, sacral slope, pelvic tilt, and fatty atrophy were significantly different in union and nonunion cohorts. The Boruta feature selection method selected BMI, age, smoking history, osteopenia/osteoporosis, anti-inflammatory use, bone mineral density, BMP use, number of posterior column osteotomy levels, number of decompression levels, and number of transforaminal interbody fusion levels as important variables to be included in the final regression model. When evaluating the model on the separate test cohort, the final model achieved an accuracy of 91.1%, sensitivity of 60.0%, specificity of 96.6%, and AUROC score of 0.86. Conclusion: This is the first study to prove ML can be used to predict pseudarthrosis in the preoperative period. The results of the Boruta selection process demonstrate that pseudarthrosis is multifactorial, with demographics, medical history, and surgical details all playing a role. While most of the factors selected by Boruta were not “statistically significant”, many of them align with clinical intuition, such as osteoporosis/osteopenia, smoking history, and the surgical factors. Despite this “statistical insignificance”, the ML model maintained a strong predictive performance, highlighting its ability to look beyond traditional statistics to fine-tune decision-making and contribute meaningful information in the clinical setting that humans may not be able to detect on face value.

ID: 358

A119: Can the recovery of root-level intraoperative neuromonitoring data result in a lower risk for a postoperative lower extremity weakness in spine deformity surgery?

Nathan Lee ¹ , Fthimnir Hassan ² , Alexandra Dionne ² , Chidebelum Nnake ² , Mitchell Yeary ² , Michael Fields ² , Matthew Simhon ² , Ted Shi ² , Varun Arvind ² , Anastasia Ferraro ² , Matthew Cooney ² , Erik Lewerenz ² , Justin Reyes ² , Steven Roth ³ , Chun Wai Hung ⁴ , Justin Scheer ⁵ , Thomas Zervos ² , Earl Thuet ⁶ , Joseph Lombardi ² , Zeeshan Sardar ² , Ronald A. Lehman ² , Lawrence Lenke ²

¹ Midwest Orthopaedics at RUSH, Chicago, United States,

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

³ University of Florida Medical Center, Gainesville, United States,

⁴ Houston Methodist, Houston, United States,

⁵ Cedar Sinai Medical Center, Los Angeles, United States,

⁶ New York Presbyterian, New York, United States

Introduction: Intraoperative neuromonitoring (IONM) is commonly used in spinal deformity surgery to reduce the risk for neurologic injury. Spinal cord data loss has been associated with postoperative deficits in prior literature; however, the clinical implications of root-level data improvement after intervention is less well understood. The purpose of this study is to determine whether the resolution of root-level IONM data alerts portends an improved rate of avoiding postoperative motor weakness. Methods: This is a retrospective, single surgeon cohort study of 1,065 patients who underwent spinal deformity surgery from 2015 to 2023. All patients underwent multimodal IONM, including bipolar recording of motor evoked potentials (MEP), somatosensory evoked potentials (SSEP), and electromyography (EMG). Root level data was reviewed with the senior member of the neuromonitoring team. Timing of IONM loss, interventions, and baseline/postoperative day 1 (POD1) lower extremity motor scores were analyzed. Results: Overall, root-level IONM loss was 3.8% (41/1065). In those 41 patients, compared to their preop motor exam, 48.8% (20/41) of patients had a POD1 deficit and 50% (10/20) of those patients had severe weakness (motor strength grade 3 or less out of 5) in the corresponding muscle group after surgery. All 41 patients had MEP changes, while 26.8% (N = 11) had SSEP changes and 17.1% (N = 7) had abnormal spontaneous EMG. Most root alerts occurred after rod (26.8%, N = 11) or screw (17.1%, N = 7) placement, or after decompression/laminectomy (14.6%, N = 6). Interventions were performed in all 41 patients with root data loss, and most required further decompression (68.3%, N = 28). After intervention, IONM data improved in 70.7% of patients (Full improvement: 36.6%, N = 15; Partial improvement: 34.1%, N = 14). For those with full and partial IONM recovery, severe weakness was denoted in 6.7% (1/15) and 21.4% (3/14) of patients, respectively. In comparison, for those without any improvement by closure, 58.3% (7/12) of patients had severe POD1 weakness (p = 0.009). Conclusions: In spinal deformity surgery, root-level data loss followed by intraoperative interventions lead to data improvement in 71% of patients. Those with full and partial recovery of IONM are significantly associated with a lower risk for severe (motor strength grade 3 or less) lower extremity weakness with an absolute risk reduction of 51.7% and 37%, respectively.

ID: 220

A120: Elevated alkaline phoshatase is associated with increased rates of pseudoarthrosis and perioperative complications following lumbar fusion surgery

Abhinav Sharma ¹ , Frederik Heath ¹ , Manaav Mehta ² , Nicole Goldenhersh ¹ , Jason Liang ¹ , Maziar Moslehyazdi ¹ , Nischal Acharya ^{1 3} , George Rublev ⁴ , Michael Steinhaus ⁵ , Hao-Hua Wu ¹ , Sohaib Hashmi ¹ , Don Park ¹ , Yu-po Lee ¹ , Zorica Buser ¹ , 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

Introduction: In the past two decades, the frequency of lumbar spine procedures and fusion surgeries has risen markedly, nearly quadrupling since 2011. This increase has coincided with a rise in postoperative complications, notably pseudoarthrosis - a failure in spinal fusion manifesting as recurring pain and mechanical instability. Alkaline Phosphatase (ALP), a biomarker linked to bone metabolism and inflammation, is traditionally used to monitor bone and liver health. The purpose of this study was to explore the association between serum ALP and the incidence of pseudoarthrosis, as well as hospital readmission and return to operating room (OR) following lumbar spinal fusion surgeries. Material and Methods: This study is a retrospective cohort study of the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP). Inclusion criteria were specific lumbar fusion surgeries (CPT codes: 22633, 22558, 22533, 22630, 22612), and documented serum ALP levels from 2015-2021. Both univariate and multivariate models were used to examine the outcome measures of pseudoarthrosis, readmission, and return to OR. These models accounted for variables including sex, smoking status, diabetes, BMI, and uremia. Analyses were further stratified by American Society of Anesthesiologist (ASA) physical status classification (I-IV). Results: 39,524 patients underwent elective lumbar fusion surgery between 2015-2021 and had a documented serum ALP level. Of these, 38,024 patients had reference ALP levels, 1,038 low, and 462 high. High ALP levels were more common in women (63.6%), obese individuals (55.9%), smokers (20.3%), as well as insulin-dependent diabetics (14.1%). Elevated ALP was significantly associated with pseudoarthrosis (odds ratio [OR] 1.62, 95% confidence interval [CI] 1.03-2.55), hospital readmission (OR 1.78, CI 1.29-2.45), and ROR (OR 2.00, CI 1.37-2.93) in the univariate analysis. Total hospital time was on average 2.15 days longer compared to reference (5.76 days, SD 6.45). Elevated ALP was associated with significantly increased odds of pseudoarthrosis (OR 1.63, CI 1.03-2.56), readmission (OR 1.65, 1.19-2.27), and return to OR (OR 1.89, 1.27-2.72) in the multivariate analysis. Stratifying by ASA class in our multivariate models, elevated ALP was associated with significantly increased odds of pseudoarthrosis (OR 2.60, 1.26-5.36), but had no association with readmission or return to the OR in ASA 2 patients. Additionally, elevated ALP was no longer significantly associated with pseudoarthrosis (OR 1.36, 0.76-2.45) or readmission rates, but was associated with increased return to the OR (OR 1.78, CI 1.12- 2.83) in ASA 3 patients. Conclusion: Elevated ALP levels are strongly associated with an increased odds of pseudoarthrosis, readmission and return to the OR among those undergoing lumbar spinal arthrodesis and retained a strong association with pseudoarthrosis and return to OR after stratifying by ASA classification. Conversely, low ALP levels may offer a protective effect against pseudoarthrosis, though not statistically significant. These results may inform surgeons of risks associated with elevated ALP levels prior to lumbar spine fusion surgery.

ID: 1501

A121: A comprehensive review of patch-based approaches for dural tear management in spine surgery

Rowen Lin 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: Dural tears are a recognized complication during spine surgery, typically addressed through suture repair. Recent advancements have introduced various dural patch alternatives, including fibrin glue, collagen matrix (DuraGen), polyethylene glycol hydrogel (DuraSeal), fibrinogen and thrombin (Tachosil), polyglycolic acid mesh, and epidural blood patches. This systematic review aims to evaluate the efficacy and performance of dural repair patches and compare the postoperative outcomes associated with these novel dural repair materials. Material and Methods: We conducted a comprehensive search across PubMed, Embase, and Cochrane Library databases following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Data extraction and quality assessment were performed using the Newcastle-Ottawa Scale (NOS). Statistical analyses were executed using STATA to evaluate the incidence rates of postoperative complications and overall efficacy of each dural repair method. Results: The review incorporated 35 articles with a total of 2,131 patients. Dural patches were predominantly used in lumbar spine surgeries (54.5%). Fibrin glue was the most frequently employed patch, used in 31.7% of cases. Tachosil demonstrated variable outcomes with postoperative CSF leakage and revision rates ranging from 0% to 18.2%. The mean length of surgery was between 98.3 and 191.7 minutes, with minimal associated postoperative complications. DuraSeal exhibited a postoperative CSF leakage and revision rate of 0% to 13.6%, and an infection rate between 0% and 10%. Epidural blood patches had a wide range of CSF leakage rates (4.3% to 75%) and reinjection rates (4.3% to 50%), with headache complications ranging from 0% to 33%. Fibrin glue alone resulted in a CSF leakage rate of 0% to 15.8% and a revision rate of 0% to 11.8%, with low rates of headache (0% to 3.2%) and infection (0% to 4.2%). Combining fibrin glue with polyglycolic acid (PGA) mesh yielded CSF leakage rates from 0% to 32%, and revision rates from 1.3% to 4.6%, with headache and infection rates of 0% to 22.6% and 0% to 2.7%, respectively. Conclusion: To our knowledge, current systematic reviews have compared direct suture techniques with dural patching, this is the first study to systematically compare the outcomes of various dural patch alternatives. The systematic review highlights variability in outcomes across different dural repair patches, reflecting the diverse efficacy and complication profiles of each method. While individual studies provide insights into the performance of each patch, there is a lack of direct comparative studies to definitively determine the most effective repair strategy. This underscores the need for further research to directly compare these dural patches and establish evidence-based guidelines for optimal dural repair in spine surgery.

ID: 376

A122: Does normalizing T4-L1PA relationship in long-segment fusions independently reduce mechanical complications and improve patient reported outcomes?

Sarthak Mohanty ¹ , Zeeshan Sardar ² , Michael Kelly ³ , Josephine Coury ² , Justin Reyes ² , Fthimnir Hassan ² , Nathan Lee ⁴ , Justin Scheer ⁵ , Steven Roth ⁶ , Chun Wai Hung ⁷ , Joseph Lombardi ² , Ronald A. Lehman ² , Lawrence Lenke ²

¹ Midwest Orthopaedics at RUSH, Boston, United States,

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

³ Rady's Childrens Hospital, San Diego, United States,

⁴ Midwest Orthopaedics at RUSH, Chicago, United States,

⁵ Cedar Sinai Medical Center, Los Angeles, United States,

⁶ University of Florida Medical Center, Gainesville, United States,

⁷ Houston Methodist, Houston, United States

Introduction: Studies in asymptomatic adults have highlighted a harmonious T4 Pelvic Angle (T4PA), L1 Pelvic Angle(L1PA) relationship, characterized by a T4PA within four degrees of L1PA. The implications of malalignment between T4PA and L1PA on mechanical complications (MCs) and patient-reported outcomes (PROs) in the context of adult spinal deformity (ASD) are significant yet not fully understood. This study investigates whether normalizing the T4-L1PA relationship in ASD patients undergoing long-segment posterior spinal fusion (PSF) reduces reoperations due to MCs and improves PROs. Methods: This is a retrospective, single center cohort study involving ASD patients who underwent PSF spanning more than six levels. T4PA-L1PA mismatch was assessed at six weeks postoperatively following deformity correction and patients were followed for two years (2Y) thereafter. Primary outcomes included mechanical complications, specifically implant-related reoperations and reoperations for proximal junctional kyphosis or failure (PJK/F), alongside the achievement of minimum clinically important differences (MCID) for Scoliosis Research Society (SRS) scores and Oswestry Disability Index (ODI) at two years postoperatively. The MCID thresholds were set at 0.4 for SRS scores and -11 for ODI. A multivariable logistic regression model investigated the association between (T4PA-L1PA)² and MC, adjusting for comorbidities (CCI), preoperative spinal alignment, upper instrumented vertebrae (UIV), pelvic fixation, and the magnitude of alignment correction. A polynomial logistic regression was employed to model the quadratic relationship between T4PA-L1PA [(T4PA-L1PA)²] and MC risk, with plots illustrating the probability of MC across the T4PA-L1PA spectrum. Logistic regression analyses investigated the relationship between (T4PA-L1PA)² mismatch and MCID attainment in PROs. Results: The cohort comprised 427 patients, with a mean age of 61.2 years, subjected to an average of 12.50 instrumented levels, 78.7% of whom received pelvic fixation. 66 (15.5%) underwent reoperations due to mechanical complications. Univariate analysis indicated that higher CCI (OR = 1.3, p = 0.001), increased (T4PA-L1PA)² (OR = 1.01, p < 0.001), lower preoperative thoracic kyphosis (TK) (OR = 0.99, p = 0.021), increased delta pelvic incidence minus lumbar lordosis (ΔPI-LL) (OR = 1.01, p = 0.037), and ΔT4PA (OR = 1.03, p = 0.029) were associated with a higher likelihood of mechanical complications. In the multivariable model (AUC = 0.72, p < 0.001), higher CCI (OR = 1.21, p = 0.029), pelvic fixation (OR = 2.78, p = 0.022), and a greater square of T4PA-L1PA mismatch (OR = 1.01, p < 0.001) emerged as independent predictors of MCs. The probability of mechanical complications revealed that both overcorrection and under correction are linked to MCs. The square of T4PA-L1PA mismatch did not correlate with achieving MCID in SRS activity (p = 0.635), pain (p = 0.444), appearance (p = 0.800), mental health (p = 0.800), satisfaction (p = 0.189), or ODI (p = 0.472). Conclusions: Normalizing the T4-L1PA mismatch within normative ranges effectively mitigates the risk of mechanical complications but does not significantly affect the attainment of MCID in patient-reported outcomes. This finding underscores that mechanical complications are driven in part by spinal alignment, whereas patient reported outcomes are possibly influenced by a broader spectrum of biopsychosocial factors.

ID: 236

A123: Increasing obesity class corresponds with greater risk of deep vein thrombosis and pulmonary embolism following elective lumbar spine surgery

Abhinav Sharma ¹ , Frederik Heath ¹ , Manaav Mehta ² , Nicole Goldenhersh ¹ , Jason Liang 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: Obesity portends worse outcomes after elective spine surgery. The effect of body mass index (BMI) classification on postoperative outcomes, pulmonary embolism (PE), and deep vein thrombosis (DVT), following elective lumbar spine surgery has yet to be previously evaluated at a large scale. The purpose of this study was to evaluate the effect of obesity class on perioperative complications following elective lumbar spine surgery. Material and Methods: Inclusion criteria were adults ≥ 18 years of age who underwent elective lumbar spine surgery from 2015 to 2021 included in the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database. 30-day post-op complication data was evaluated using multivariate models examining the risk of return to OR, readmission, PE, and development of DVT. Obesity was further classified as type 1 (BMI 30-34.9), type 2 (BMI 35-39.9), and type 3 (BMI > 40). Predictors included BMI category, age, sex, smoking, diabetes, uremia, BUN creatinine ratio, malnourished and ASA classification. Results: Of 39,522 patients who met inclusion criteria, 285 patients developed a DVT requiring therapy and 235 developed a PE. Type 2 obesity was significantly associated with DVT in both univariate (odds ratio [OR] 1.76, 95% confidence interval [CI] 1.15-2.70) and multivariate models (OR 1.83, CI 1.19-2.81). Both types 2 and 3 obesity were significantly associated with PE on both univariate (OR 2.78, CI 1.71-4.52; OR 2.31, CI 1.31-4.48) and multivariate modeling (OR 2.94, CI 1.80-4.81; OR 2.51, CI 1.41-4.48). Type 3 obesity was significantly associated with hospital readmission on univariate (OR 1.43, CI 1.20-1.70) and multivariate modeling (OR 1.50, CI 1.26-1.80). All three obesity types were significant for return to OR on univariate and multivariate modeling, respectively: type 1 (OR 1.37, CI 1.07-1.75; OR 1.38, CI 1.07-1.76); type 2 (OR 1.80, CI 1.39-2.34; OR 1.80, CI 1.38-2.35); type 3 (OR 1.77, CI 1.30-2.40; OR 1.74, CI 1.27-2.39). Older age (OR 1.02, CI 1.01-1.03) and malnourishment (OR 1.60, CI 1.05-2.43) were significantly associated with DVT. Older age (OR 1.02, CI 1.01-1.03) was the only non-BMI variable significant for PE. Conclusion: Increasing BMI results in elevated postoperative complication, readmission, and reoperation risks following elective lumbar spine surgery. Due to the elevated risk of poorer outcomes according to severity of obesity, multidisciplinary counseling and possible deferral of elective surgery until nutritional status is optimized and bariatric evaluation is complete may be warranted.

ID: 751

A124: Outcome and safety of expansion duroplasty in acute spinal cord injury during thoracic ossified ligamentum flavum surgery

Shahid Ali ¹ , Muhammad Jawad Saleem ¹ , Abubakar Atiq Durrani ² , Shahzaib Baloch ³

¹ Orthopedic Spine Institute, Spine Surgery, Orthopedic Sugery, Lahore, Pakistan,

² Orthopedic Spine Institute, Spine Sirgery, Orthopedic Sugery, Lahore, Pakistan,

³ Orthopedic Spine Institute, Spine Surgery, Lahore, Pakistan

Introduction: Thoracic Ossified Ligamentum Flavum (TOLF) is a rare condition but can lead to severe neurological complications due to spinal cord compression. Surgical intervention, although necessary, carries a significant risk of neurological injury. In the event of intraoperative neurological injury, the literature lacks effective remedies aside from extending laminectomy. Expansion Duroplasty (ED), which has been shown to improve physiological parameters in cases of acute traumatic spinal cord injury, could offer a potential solution. Neurological injuries during TOLF surgery may represent reperfusion injuries due to a sudden increase in cerebrospinal fluid (CSF) flow, leading to elevated intradural pressure; we coin this term as intra-spinal hypertension (ISH). ED has been hypothesized to relieve this pressure. This study presents the outcomes and safety of ED in treating acute spinal cord injury during TOLF surgery. Material and Methods: This prospective case series was conducted at the Orthopedic Spine Institute, Doctors Hospital & Medical Centre, Lahore, from January 1, 2020, to December 31, 2022. The study recruited 10 consecutive patients undergoing TOLF surgery who experienced intraoperative neurophysiological monitoring (IONM) drops. Patients were followed prospectively, and assessments included the Modified Japanese Orthopaedic Association (MJOA) scoring system, X-rays, CT scans, and MRI. Facia Lata or synthetic grafts were used for ED. IONM was continuously monitored during surgery, with a drop in IONM serving as the trigger for ED. Upon IONM drop, a Durotomy and arachnoid excision were performed, followed by the application of a fascia lata or synthetic patch. Patients were assessed on MJOA immediate post op & at 12months. Results: Cohort consisted of 10 patients with a mean age of 45 years, and a male-to-female ratio of 2:1. The mean follow-up period was 12 months. TOLF levels varied, with 5 patients at T9-10, 3 at T10-11, and 2 at T5-6. Seven patients had associated cervical ossification of the posterior longitudinal ligament (OPLL), and all had preoperative myelopathic symptoms, while 7 patients exhibited myelomalacia on MRI. Preoperatively, 3 patients had a Modified JOA score of 6, 5 patients had a score of 4, and 1 patient had a score of 9. From the sample size 4 patients improved their MJOA scores by 2 grades whereas 2 patients had an improvement by 1 grade while rest of the patients remained unchanged. Average operation time was 4 hours. No patient experienced neurological deterioration postoperatively. Hyperreflexia and spastic gait persisted in all. One patient developed a superficial wound infection, but no cases of deep infection or meningitis occurred. Conclusion: Expansion Duroplasty (ED) appears to be a safe and effective intervention for managing neurological injury during OLF surgery. It is not associated with any worsening of neurological function and demonstrates potential for improving neurological outcomes. However, further studies with larger sample sizes are warranted to confirm these findings and assess the long-term benefits of ED in such cases.

Keywords: Thoracic Ligamentum Flavum (TOLF), Intra-spinal Hypertension (ISH), Expansion Duroplasty (ED)

ID: 571

A125: Complications of anterior lumbar interbody fusion in patients with a primary hypercoagulopathy

Henry Avetisian ¹ , William Karakash ¹ , Maya Abu-Zahra ¹ , Chimere Ezuma ¹ , Bahador Athari 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

Introduction: Anterior lumbar interbody fusion (ALIF) is a common spine procedure, with complications including venous laceration, retroperitoneal hemorrhage, thrombosis, and ileus. Given the risks of hemorrhage and thrombosis during ALIF, it is crucial to understand the impact of primary hypercoagulable disorders on surgical outcomes. Currently, there is a gap in the literature regarding these effects. This retrospective study aims to examine the impact of primary hypercoagulable disorders on ALIF complications. We hypothesize that patients with these disorders are at increased risk of complications compared to those with normal coagulation profiles. Material and Methods: The PearlDiver national patient database was queried for patients with a primary hypercoagulopathy (e.g., Factor V Leiden, Protein C&S deficiency, antiphospholipid syndrome, lupus anticoagulant) who underwent ALIF between 2010 and 2022. Exclusion criteria included patients under 18 years, less than two years of preoperative follow-up, or operative indications for trauma, malignancy, or infection. Primary endpoints included the prevalence of hypercoagulable disorders in ALIF patients and the 30- and 90-day risks of postoperative complications, revision surgery, and readmission. Results: A total of 171,334 patients who underwent ALIF from 2010-2022 were identified, with 2,693 (1.57%) having a hypercoagulable disorder. The hypercoagulable cohort had significantly higher 30-day (7.43% vs 5.85%, OR = 1.29, 95% CI: 1.04-1.61, p < 0.05) and 90-day (8.93% vs 6.93%, OR = 1.32, 95% CI: 1.08-1.61, p < 0.01) readmission rates compared to controls. Additionally, 30-day rates of infection (4.16% vs 3.0%, OR = 1.40, 95% CI: 1.04-1.88, p < 0.05), DVT (3.27% vs 0.62%, OR = 5.46, 95% CI: 3.19-9.34, p < 0.001), and PE (2.31%, OR = 8.75, 95% CI: 3.99-19.18, p < 0.001) were higher in the hypercoagulable group. Surgical complications such as postoperative hemorrhage (0.77%, OR = 2.87, 95% CI: 1.21-6.80, p < 0.05) and hematoma (1.77% vs 0.81%, OR = 2.21, 95% CI: 1.32-3.72, p < 0.01) were also more common. Overall, all 30-day medical complications (16.63% vs 11.94%, OR = 1.47, 95% CI: 1.26-1.72, p < 0.001) were significantly higher in the hypercoagulable cohort. At 90 days, the cohort showed increased DVT (4.89% vs 0.92%, OR = 5.51, 95% CI: 3.55-8.56, p < 0.001), PE (3.32%, OR = 9.61, 95% CI: 4.82-19.16, p < 0.001), postoperative hemorrhage (0.96%, OR = 2.80, 95% CI: 1.30-6.0, p < 0.05), and hematoma (2.23% vs 1.04%, OR = 2.17, 95% CI: 1.37-3.44, p < 0.001). All 90-day medical complications were also significantly higher (23.33% vs 16.79%, OR = 1.51, 95% CI: 1.32-1.73, p < 0.001). Conclusion: Patients with hypercoagulable disorders undergoing ALIF are at increased risk for infection, hematoma formation, hemorrhage, DVT, and PE within 90 days post-procedure. Further research is needed to develop standardized guidelines for VTE prophylaxis in this patient population.

ID: 845

A126: Factors that influence the time course of recovery for post-operative C5 palsy

Rachel Huang ¹ , Jonathan Dalton ¹ , Michael Carter ¹ , Gregory Toci ¹ , Rajkishen Narayanan ¹ , Andrew Kim ¹ , Robert Oris ¹ , Chloe Herczeg ¹ , Joydeep Baidya ¹ , Jarod Olson ¹ , Jose Canseco ¹ , Alan Hilibrand ¹ , Alex Vaccaro ¹ , Chris Kepler ¹ , Gregory Schroeder ¹

¹ Rothman Orthopaedic Institute, Philadelphia, United States

Introduction: C5 palsy is a common and debilitating complication following cervical spine surgery with a prognosis that can be difficult to predict. No prior studies have examined risk factors predictive of timing of C5 palsy recovery. The purpose of this study is to assess the impact of demographic and surgical factors on postoperative C5 palsy recovery timing. Material and Methods: Adult patients with C5 palsy after either anterior or posterior cervical discectomy and fusion (ACDF, PCDF, respectively) were identified (2010-2023). Patient demographics and surgical variables were recorded. Patients were divided by resolution to preoperative strength at six months and one year after surgery. Appropriate statistical analysis was performed with alpha < 0.05. Results: 94 patients had postoperative C5 palsy after PCDF: 63 (67.0%), ACDF: 22 (23.4%), ACDF/PCDF: 6 (6.4%), and laminoplasty: 3 (3.2%). Patients resolved by 6 months were more likely to be younger (60.1 ± 12.4 vs. 66.0 ± 10.4; p = 0.009), female (44.7% vs 19.2%; p = 0.018), have a lower CCI (2.76 ± 2.10 vs. 3.40 ± 1.60; p = 0.032), and have higher deltoid (3.03 ± 1.1 vs. 1.79 ± 1.13; p < 0.001) and biceps (4 ± 0.93 vs. 2.96 ± 1.12; p < 0.001) strength at diagnosis. Biceps involvement was associated with failure to recover at six months (42 (80.8%) vs. 21 (55.3%); p = 0.018). Similar factors were associated with recovery at one year after surgery. Procedure type was not found to be independently predictive of recovery timing after controlling for levels fused. 71% of all patients recovered within one year. Conclusion: Earlier C5 palsy recovery was associated with being younger, female, and having higher muscle strength at diagnosis. Patients with biceps involvement recovered slower. Procedure type was independently predictive for timing of recovery, controlling for levels fused. Identifying these risk factors can enhance patient counseling.

OP15: Degenerative Lumbar Spine Surgery 1

ID: 1277

A127: Are PROMS enough? Using functional tests to assess the outcome of spinal fusion surgery

Patrick Beaumont ¹ , Xanthe Meehan ¹ , Matthew Blackman ¹ , Paul Licina ¹

¹ SpinePlus, Brisbane Private Hospital Spine Research Group, Brisbane, Australia

Introduction: PROMs are now the standard method of assessing outcome after spinal fusion surgery. However, there are questions about their sensitivity and specificity. Our aim was to develop a combination of functional tests to increase the objectivity of outcome measurement. We chose to measure three domains, namely strength, balance and flexibility. We developed two methods, the first being clinical tests using minimal equipment, and the second being mechanical tests using specialised equipment. Material and Methods: A prospective study was performed on patients undergoing lumbar fusion surgery through a single surgeons practice from March 2022 to September 2023. Participants completed two physical assessment (clinical and mechanical) at the pre-operative and 6-month post-operative timepoints. The clinical assessment consisted of measures of trunk flexion and extension endurance, standing balance, trunk flexibility (trunk flexion | combined extension, lateral flexion and rotation), and clinical combined tests such as the 30-second sit-to-stand and the timed-up-and-go. The mechanical assessment evaluated the same physical domains; however, validated testing equipment was used for all measures, including a force measurement device for trunk flexion and extension strength, force plates for assessing balance (total distance and area of sway), and wearable sensors for flexibility. The outcomes of each test within the clinical and mechanical assessments were first considered individually, and following this, the outcomes were combined in an unweighted fashion to give an overall clinical and mechanical score. Participants completed questionnaires relating to back and leg pain (VAS | 0-10 | clinically meaningful change = 1.5-points) and disability using the Oswestry disability index (ODI |0-100%| clinically meaningful change = 20-points) at baseline and 6-months post-operatively. For surgery to be considered a success, participants needed to have achieved a meaningful decrease in two of the three questionnaires. Results: 47 participants completed the pre- and post-operative assessments, 38 were classified as a surgery success and 9 as unsuccessful. Observing the clinical tests individually, weak positive correlations were seen between scores of left (R = 0.331; p = 0.023) and right (R = 0.415; p = 0.004) combined flexibility and achieving a successful outcome. No other significant correlations were observed across any of the clinical tests. When combining the tests into a sum score, it was shown that higher sum scores correlated with achieving a PROMS success (R = 0.332; p = 0.023). When assessing the mechanical tests individually, measures of single leg balance were shown to correlate with PROMs success. Specifically, a lower total sway on the left (R = -0.328; p = 0.026) and lower area of way on the right (R = -0.398; p = 0.024) were the only correlates with PROM success. Although, when combining the results from each test into a sum score, this did not correlate with success. Conclusion: Defining success after spine surgery is challenging, and relying only on subjective PROMs can be misrepresentative of the patient’s true condition. Specific components of objective physical testing show promise for assisting in defining success. Our future aim is to utilise machine learning to determine which of the physical tests contribute most to success, and what the optimal combination of tests is to give a holistic physical assessment.

ID: 405

A128: Utility of preoperative carboxyhemoglobin level as a predictor of surgical outcomes following transforaminal and posterior lumbar interbody fusion

Ryan Kempski 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: Smoking and tobacco use is known to increase postoperative complications and poor clinical outcomes following spinal fusion. Obtaining carboxyhemoglobin (COHb) levels is commonly performed during preoperative screening as an objective measure of patient smoking exposure. However, there is limited data on the use of COHb levels to predict outcomes following transforaminal or posterior lumbar interbody fusion (TLIF/PLIF). The purpose of this study is to (1) identify the relationship between preoperative COHb levels, surgical complications, and patient reported outcome measures following TLIF/PLIF, (2) determine if a clinically relevant cutoff for COHb level exists, and (3) compare outcomes between open and minimally invasive (MI) techniques. Material and Methods: A retrospective analysis was performed identifying patients who underwent single-level elective TLIF/PLIF from 2017-2022. Preoperative COHb levels, demographics, surgical technique, and complications were obtained via electronic health records. Patient-Reported Outcomes Measurement Information System (PROMIS) and Oswestry Disability Index (ODI) scores were collected perioperatively. Delta (∆) PROMIS and ODI was calculated from the difference between scores at preoperative and latest follow-up. A minimal clinically important difference (MCID) of 10 was used for ODI and 8 for PROMIS based on previous literature. Descriptive and inferential statistics were performed. Results: A total of 325 (open, n = 285; MIS, n = 40) patients were included. Average follow-up time was 2.2 ± 1.1 years (range: 0.02-4.06 years). Increased preoperative COHb levels were found to be associated with a decreased ∆PROMIS overall (r = -0.266, p = 0.010; B = -3.216, p = 0.010), ∆PROMIS physical score (r = -0.225, p = 0.031; B = -3.669, p = 0.031), and ∆PROMIS mental score (r = -0.302, p = 0.003; B = -5.161, p = 0.003). No associations were found between increased COHb and ∆ODI (p = 0.686), complications (p = 0.691), or mortality (p = 0.334). A preoperative COHb level cutoff of 0.95% correlated with a sensitivity/specificity of 100%/36.4% for ∆ODI of 10 [area under curve = 0.608]. There was no cutoff value for ∆PROMIS that met MCID. Compared to the open cohort, the MI cohort had a greater proportion of smokers (27% vs. 10%, p = 0.023) and higher COHb levels (2.9 ± 1.5 vs. 1.5 ± 1.0, p < 0.0001). Similar long-term outcomes were observed between the two groups for ∆PROMIS-overall [MI: 9.0 ± 7.3, open: 10.5 ± 12.5, p = 0.794] and ∆ODI [MI: 11.2 ± 46.3, open: 10.1 ± 29.5, p = 0.935]. There was no difference in surgical complications [MI: 5 (13%), open: 57 (20%), p = 0.389] or mortality [MI: 0 (0%), open: 11 (4%), p = 0.372]. Conclusion: Our findings suggest higher preoperative carboxyhemoglobin levels are associated with decreased PROMIS scores postoperatively following elective TLIF/PLIF. A cutoff of 0.95% was associated with a long term ∆ODI improvement less than MCID, although its overall predictive value is poor. Despite MIS patients having a significantly higher proportion of smokers than open patients, both groups maintained similar complications and outcomes. This suggests that minimally invasive techniques may confer a protective effect against surgical complications among current smokers.

ID: 2660

A129: Vertebroplasty combined with transpedicular fixation for the management of non-traumatic osteoporotic vertebral fractures associated with pedicle fractures

Hamisi Mraja ¹ , Baris Peker ² , Tunay Sanli ¹ , Sepehr Asadollahmonfared ¹ , Enas Daadour ¹ , Mehmet Zamanoglu ¹ , Onur Levent Ulusoy ¹ , Selhan Karadereler ¹ , Meric Enercan ² , Azmi Hamzaoglu ¹

¹ Scoliosis and Spine Center, Istanbul, Turkye

² Demiroglu Bilim University, Istanbul, Turkye

Introduction: Non-traumatic osteoporotic vertebra fracture (OVF) in association with bilateral pedicle fractures is a rare condition. Especially OVFs demonstrating vacuum cleft sign and superior endplate discontinuity extending to the posterior cortex may be associated with non-traumatic pedicle fractures. This co-existence results in an unstable fracture pattern and when solely treated with vertebroplasty, such patients can develop further vertebral collapse which leads to dead bone formation. The aim of this study is to evaluate the efficacy of vertebroplasty combined with transpedicular fixation for the management of OVFs associated with pedicle fractures. Material and Methods: Patients who were treated with vertebroplasty combined with percutaneous transpedicular fixation with fenestrated screw at same level of the osteoporotic vertebra fracture. Prophylactic vertebroplasty was performed one level above and below. All patients underwent MRI and CT scans during preop evaluation. Preop and postop CT scans used for vertebral height measurements and comparison. Results: 32 OVF patients (10 M, 22 F) with a mean age 74 (47-92) years and a mean f/up 30 (24-74) months were included. Q-CT analysis including BMD and T-score mean values was 56.79 mg/cm3 and -4.38 ± 0.538 respectively. Vertebroplasty combined with transpedicular fixation was performed at Thoracolumbar in 21 patients, Thoracic in 8 patients and Lumbar spine in 3 patients. Prophylactic vertebroplasty was performed at 87 levels. The mean vertebral body angle improvement was 20.9% and the mean local kyphosis angle improvement was 17.2%. Mean anterior vertebral height and posterior vertebral height increased by 13.5% and 3.5%, respectively. None of the patients developed further vertebral collapse and none of the pedicle screws pulled out at the final f/up. Conclusion: According to our study, vertebroplasty combined with transpedicular fixation provided stable fixation and prevented further vertebral collapse in all patients with osteoporotic vertebra fracture associated with pedicle fractures. O osteoporotic vertebra fractures having vacuum cleft sign or superior endplate discontinuity extending to the posterior cortex must be evaluated for the co-existence of a spontaneous pedicle fracture which causes instability and vertebral collapse. We recommend routine preop CT scan evaluation to determine the fracture pattern and check pedicle integrity in addition to MRI scans.

ID: 1582

A130: ALIF and expandable - TLIF achieve similar lordosis and disc height at L5-S1

Jackson Byrd ¹ , Nate Buchanan ¹ , Saurabh Rawall ¹ , Zuhair Mohammed ¹ , Asa Peterson ¹ , Luke Hiatt ¹

¹ University of Alabama at Birmingham, Department of Orthopaedic Surgery, Birmingham, United States

Introduction: Anterior lumbar interbody fusion (ALIF) and transforaminal lumbar interbody fusion (TLIF) are the most common techniques to achieve L5-S1 fusion. The fusion rates and clinical outcomes for TLIF are comparable to ALIF. ALIF is reported to be superior to TLIF in restoring lordosis and foraminal height. The disadvantages of ALIF are that it requires repositioning, an extra approach, an access surgeon and possibly two staged surgery. Moreover, it doesn’t allow direct decompression. Expandable-TLIF can restore segmental lordosis, disc height and foraminal height better than static-TLIF. However, no clinical study has compared the radiological results of ALIF and expandable-TLIF at L5-S1. Materials and Methods: We included all patients who underwent L5-S1 fusion at our institution, with an expandable-TLIF or ALIF, from 2015 to 2023. We recorded demographic data, interbody device details and surgical details. Additionally, we compared preop radiological data (including anterior and posterior disc heights, disc angle, L5-S1 sagittal lordotic angle, L4-S1 sagittal lordotic angle and L1-S1 sagittal lordotic angle) to x-rays done at first and second postop visit. Results: The final cohort consisted of 158 patients (114 ALIF and 44 expandable-TLIF). ALIF cohort showed significantly higher surgical times, anaesthesia time as well has higher percentage of staged procedures. Expandable-TLIF cohort had significantly more instrumented levels, increased S2AI screws use, along with increased device lordosis. For ALIF, between pre-op and first follow-up imaging, we found significant differences in anterior disc height (9.53 vs. 21.24, p ≤ 0.0001), posterior disc height (4.22 vs. 9.48, p ≤ 0.0001), interdisc angle (9.06 vs. 17.98, p ≤ 0.0001), L5-S1 cobb angle (17.88 vs. 24.88, p ≤ 0.0001), L4-S1 cobb angle (29.38 vs. 38.67, p ≤ 0.0001), and L1-S1 cobb angle (40.93 vs. 50.01, p ≤ 0.0001). Between pre-operation and second follow up, we found significant difference in anterior disc height (9.53 vs. 19.94, p ≤ 0.0001), posterior disc height (4.22 vs. 8.44, p = 0.0001), interdisc angle (9.06 vs. 18.25, p = 0.0001), L5-S1 cobb angle (17.88 vs. 24.27, p ≤ 0.0001), L4-S1 Cobb angle (29.38 vs. 38.21, p ≤ 0.0001), and L1-S1 Cobb angle (40.93 vs. 51, p ≤ 0.0001. For expandable-TLIF, between pre-op and first follow-up imaging, we found significant differences in anterior disc height (11.00 vs. 19.64, p ≤ 0.0001), posterior disc height (5.23 vs. 7.95, p ≤ 0.0001), interdisc angle (10.23 vs. 18.81, p ≤ 0.0001), L5-S1 Cobb angle (18.68 vs. 26.58, p ≤ 0.0001), L4-S1 Cobb angle (30.24 vs. 38.75, p ≤ 0.0001) and L1-S1 Cobb angle (45.31 vs. 51.98, p = 0.0004). Between pre-op and second follow up radiographs, we found significant differences between anterior interdisc height (11.00 vs. 19.16, p ≤ 0.0001), posterior interdisc height (5.23 vs. 7.77, p ≤ 0.0001), interdisc angle (10.23 vs. 16.57, p ≤ 0.0001), L5-S1 Cobb angle ( 18.68 vs. 24.93, p ≤ 0.0001), L4-S1 Cobb angle (30.24 vs. 36.34, p = 0.0011) and L1-S1 Cobb angle (45.31 vs. 49.38, p = 0.0109). Conclusion: Our findings indicate that expandable-TLIF is comparable to ALIF in restoring lordosis and disc height at L5-S1. Expandable-TLIF at L5-S1 allows for an ideal single position posterior surgery with similar radiological outcomes as ALIF. This is especially beneficial for complex multilevel fusions by obviating the need for an additional anterior surgery.

ID: 1963

A131: “One and a half” minimally invasive transforaminal lumbar interbody fusion (MIS TLIF): A single center retrospective case series

Chibuikem Ikwuegbuenyi ¹ , Minaam Farooq ¹ , Rodolfo Villalobos ¹ , Andreas Kramer ¹ , Mousa Hamad ¹ , Noah Willett ¹ , Ibrahim Hussain ¹ , Galal Elsayed ¹ , Osama Kashlan ¹ , Roger Härtl ¹

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

Introduction: Spondylolisthesis with multilevel stenosis is traditionally treated with open decompression and multilevel fusion, which can lead to adjacent segment degeneration and postoperative complications. Our group's recent biomechanical study demonstrated that minimally invasive (MI) tubular decompression causes significantly less instability than open laminectomy at the adjacent level of MI-TLIF. Based on these findings, we implemented the “One and a Half TLIF” approach in our clinical practice for patients with multilevel lumbar stenosis, combining MIS fusion at the unstable segment with unilateral laminotomy for bilateral decompression at adjacent level with stenosis. This study aims to assess the rate of reoperation, specifically the extension of fusion to the adjacent decompressed level, along with evaluating clinical outcomes in pain and disability, radiological outcomes, and associated complications, with a minimum follow-up of one year. Material and Methods: We conducted a retrospective, single-center case series of patients who underwent the “One and a Half TLIF” procedure by a single surgeon between 2015 and January 2023. Hospital records, imaging, and pre-and post-operative assessments were reviewed. Radiological outcomes were measured using lumbar spine X-rays and sagittal CT scans. Pseudarthrosis was defined as the absence of bony bridging lucency, with ≥2 degrees angulation changes or ≥1 mm translation in flexion-extension X-rays, and subsidence as >2 mm loss in intervertebral height from post-op to follow-up. Pain (NRS) and disability (ODI) scores were used to assess clinical outcomes. Wilcoxon Signed Rank Test and paired t-test were used for statistical analyses, with significance set at 0.05. All analyses were performed in R Studio. Results: Thirty-three patients underwent “One and a Half TLIF” with median clinical and radiological follow-ups of 26.88 and 12 months, respectively. All patients had one-level fusion, with L4-5 being the most common fused level, while L3-4 (53.8%) was the most common decompressed level. The reoperation rate was 6.1%, with two patients requiring fusion extension. Median NRS-L improved significantly from 5.5 preoperatively to 0 at follow-up (p = 0.022). ODI improved from 38 preoperatively to 13.5 at follow-up (p = 0.008). At the fused level, anterior disc height increased from 6.5 mm preoperatively to 11 mm postoperatively, with a follow-up median of 8.5 mm (p < 0.001). Posterior disc height increased from 4.1 mm to 8 mm postoperatively, with a follow-up median of 6.6 mm (p < 0.001). Right foraminal height increased from 14.8 mm to 18.1 mm postoperatively, with a follow-up median of 16.6 mm (p < 0.001), with similar improvements on the left. Lumbar lordosis improved from 40.4° preoperatively to 45.1° at follow-up (p < 0.05). The subsidence rate was 19.2%, and the fusion rate was 96.2%. No major complications were reported, including neurological deterioration or reoperations within 30 days. Conclusion: The “One and a Half TLIF” approach demonstrates promising results for managing spondylolisthesis with multilevel stenosis. It significantly improves pain, disability, and radiological outcomes, offering a less invasive and effective alternative to traditional multilevel fusion. This technique has the potential to reduce adjacent segment degeneration and postoperative complications.

ID: 1417

A132: Rates of lumbar spine fusion following sacroiliac joint fusion

William Karakash ¹ , Henry Avetisian ¹ , Ali Issani ¹ , Ram Alluri ¹ , John Liu ² , Jeffrey C. Wang ¹ , Marc Abdou ¹

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

² Keck School of Medicine of USC, Department of Neurological Surgery, Los Angeles, United States

Introduction: The sacroiliac (SI) joint is increasingly recognized as a potential source of low back pain, with estimates suggesting it may account for up to 30% of cases. SI joint fusion has proven effective in improving pain, physical function, and quality of life for individuals with SI dysfunction and pain. As a result, the frequency of SI joint fusion procedures has risen significantly and is expected to continue increasing, particularly given the aging population. While it is well-established that a history of lumbar fusion increases the risk of subsequent SI joint fusion due to stress transfer from the lumbar spine to the SI joint, the reverse relationship - whether SI joint fusion increases the likelihood of subsequent lumbar fusion - remains unexplored. This study aims to investigate whether SI joint fusion increases the likelihood of subsequent lumbar fusion. Methods: A retrospective analysis was conducted using the PearlDiver Mariner database to identify patients diagnosed with lumbar degenerative disease (LDD) between 2010-2022. Patients were divided into two cohorts: those with a history of SI joint fusion and those without. We compared the rates of subsequent lumbar spine fusion between the two groups. Relevant diagnoses and procedure codes were extracted using International Classification of Disease, 9th and 10th Edition (ICD-9, ICD-10) and Current Procedural Terminology (CPT). Statistical analysis employed student’s t-tests for continuous data and chi-squared analyses for categorical data. Results: This study identified 46,147,409 patients diagnosed with lumbar degenerative disease during the study period. Of these, 19,849 (0.04%) had undergone sacroiliac (SI) joint fusion. Among patients without a history of SI joint fusion, 608,909 (1.32%) underwent subsequent lumbar fusion. In contrast, in patients with a history of SI joint fusion, 8,589 patients (43.27%) underwent subsequent lumbar fusion. Statistical analysis revealed that a history of SI fusion was significantly associated with subsequent lumbar fusion in patients with lumbar degenerative disease (OR = 23.18 [95% CI: 22.8-23.6], p < 0.001). Discussion: This study reveals that patients with LDD who have undergone SI joint fusion are significantly more likely to require subsequent lumbar spine fusion compared to those without prior SI joint fusion. This information is crucial for spine surgeons when counseling patients who are candidates for SI joint fusion, as the potential for future lumbar fusion should be a critical component of the shared decision-making process. These results also contribute to the broader understanding of spinal biomechanics. The high rate of subsequent lumbar fusion observed suggests that SI joint fusion significantly alters the stress distribution in the spine. The redistribution of forces may accelerate lumbar degeneration, potentially explaining the increased need for lumbar fusion in these patients. Furthermore, these findings have implications for healthcare costs and resource utilization. Patients who undergo SI joint fusion may require more extensive long-term care and follow-up. Future research should focus on elucidating the biomechanical changes following SI joint fusion, identifying the optimal surgical candidate, and developing strategies to mitigate the risk of subsequent lumbar degeneration.

ID: 554

A133: Influence of frailty on clinical and radiological outcomes in patients undergoing transforaminal lumbar interbody fusion with the use of an expandable interbody device - institutional analysis of 433 patients and 538 treated segments

Yesim Yildiz ¹ , Stefan Motov ¹ , Lorenzo Bertulli ¹ , Felix Stengel ¹ , Gregor Fischer ¹ , Linda Bättig ¹ , Francis Kissling ¹ , Laurin Feuerstein ² , Daniele Gianoli ² , Thomas Schöfl ² , Benjamin Martens ² , Martin Stienen ¹ , Nader Hejrati ¹

¹ Cantonal Hospital of St. Gallen & Medical School of St. Gallen, Department of Neurosurgery, Spine Center of Eastern Switzerland, St. Gallen, Switzerland,

² Cantonal Hospital of St. Gallen & Medical School of St. Gallen, Department of Orthopedic Surgery, Spine Center of Eastern Switzerland, St. Gallen, Switzerland

Purpose: The purpose of this study was to analyse the influence of frailty on cage subsidence, fusion rates, complications and clinical outcomes in patients undergoing transforaminal lumbar interbody fusion (TLIF). Methods: In a retrospective, single-centre observational cohort study we reviewed n = 433 patients treated by posterior lumbar fusion, including TLIF with an expandable interbody device on 538 spinal levels. Parameters of interest included demographic, clinical, radiological, surgical and clinical outcome variables. Patients were grouped into vulnerable/frail (n = 142) versus well/fit (n = 291), according to the Canadian Frailty Index. Results: Frail patients were significantly older (63.3 vs 69.0 years, p < 0.001), had worse American Society of Anesthesiologists (ASA) and Charlson Comorbidity Index (CCI) grades (both p < 0.001) and had a higher number of fused segments (2.3 vs 3.1 segments, p = 0.002) due to underlying adult spinal deformity (12.7% vs. 4.8%, p = 0.032). Postoperative AEs until discharge (25.4% vs 41.5%, p = 0.001), at three (10.7% vs 23.9%, p = 0.001) and 12 months (6.5% vs 20.4%, p < 0.001) occurred more frequently and were more severe in frail patients (all p < 0.05). Cage subsidence was seen more often in frail patients at time of discharge (14.8% vs 24.6%, p = 0.012) and at 12 months (22.7% vs 34.5%, p = 0.026). In univariate logistic regression, frail patients were more likely to experience a postoperative AE until discharge (OR 2.11, 95%CI 1.38-3.22), 90 days (OR 1.59, 95%CI 1.1-2.3) and 12 months (OR 3.85, 95%CI 2.04-7.26) and less likely to have a favorable 12-month outcome (OR 0.66, 95%CI 0.46-0.96). Multivariable logistic regression, adjusted for confounders, showed that frailty was an independent risk factor for postoperative AE’s at 12 months (OR 3.51, 95% CI 1.76-6.99), while keeping a tendency for inferior clinical outcome (OR 0.69, 95% CI 0.44-1.07). Conclusions: In this series, frailty had a negative influence on the rate of AEs and clinical outcomes until 12 months in patients undergoing posterior spinal fusion with TLIF. More data is needed to evaluate whether preoperative medical optimization or prehabilitation positively impacts patient reported outcomes.

ID: 562

A134: Preoperative determinants of postoperative expectation fulfillment following elective lumbar spine surgery: an observational study from the Canadian Spine Outcome Research Network (CSORN)

Vishwajeet Singh ¹ , Andrew Glennie ² , Eugene Wai ³ , Michael Weber ⁴ , Raphaële Charest-Morin ⁵ , Najmedden Attabib ⁶ , Chris Small ⁶ , Adrienne Kelly ⁷ , Supriya Singh ⁸ , Bernanrd LaRue ⁹ , Sean Christie ² , Daryl Fourney ¹⁰ , Jerome Paquet ¹¹ , Andrew Nataraj ¹² , Nicolas Dea ⁵ , Neil Manson ⁶ , Chris Bailey ⁸ , Raja Rampersaud ¹³ , Alex Soroceanu ¹ , Charles Fisher ⁵ , Andrew Schoenfeld ¹⁴ , Greg McIntosh ¹⁵ , Ken Thomas ¹

¹ University of Calgary Spine Program, Division of Orthopedics, Department of Surgery, Calgary, Canada,

² Dalhousie University, Division of Orthopedic Surgery, Halifax, Canada,

³ Ottawa Hospital, Division of Orthopedic Surgery, Ottawa, Canada,

⁴ Department of Orthopaedic Surgery, University of Montreal Health Centre, McGill University & Montreal General Hospital, Montreal, PQ, Canada, Montral, Canada,

⁵ Combined Neurosurgical and Orthopedic Spine Program, University of British Columbia, Vancouver, BC, Canada, Vancouver, Canada,

⁶ Division of Orthopaedics, Canada East Spine Centre and Horizon Health Network, Saint John, NB, Canada, Saint John, Canada,

⁷ Sault Area Hospital, Northern Ontario School of Medicine, Sault Ste. Marie, ON, Canada, Sault Ste Marie, Canada,

⁸ London Health Sciences Centre Combined Orthopaedic and Neurosurgery Spine Program, Schulich School of Medicine, Western University, London, ON, Canada, London, Canada,

⁹ Department de chirurgie, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, QC, Canada, Sherbrooke, Canada,

¹⁰ Department of Surgery, University of Saskatchewan, Saskatoon, SK, Canada, Saskatoon, Canada,

¹¹ Centre de Recherche CHU de Quebec, CHU de Quebec-Universite Laval, Quebec, Quebec, Canada, Quebec city, Canada,

¹² Division of Neurosurgery, Department of Surgery, University of Alberta, Edmonton, AB, Canada, Edmonton, Canada,

¹³ Schroeder Arthritis Institute, Krembil Research Institute, University Health Network, University of Toronto, Toronto, ON, Canada, Toronto, Canada,

¹⁴ Department of Orthopedic Surgery, Brigham and Women's Hospital, and Harvard Medical School, Boston, MA, USA, Boston, United States,

¹⁵ Canadian Spine Outcomes and Research Network, Markdale, ON, Canada, Markdale, Canada

Introduction: Preoperative patient factors determining expectation fulfillment from elective lumbar surgeries are poorly defined. The objective of the study was to identify preoperative factors associated with the levels of expectation fulfillment following elective lumbar spine surgery. Material and Methods: This retrospective cohort study used the Canadian Spine Outcome Research Network (CSORN) registry data with participants enrolled between January 2015 and December 2020. The registry prospectively enrolled surgical patients for the treatment of spinal disorders from twenty-three sites. Participating patients completed preoperative and follow-up questionnaires, including information on expectations from surgery. Patients recorded their levels of expectation fulfillment on a Likert scale of 1-5, with responses ranging from Completely met (5) to Not applicable (1) in seven expectation dimensions. Consecutive patients with four lumbar conditions (spinal stenosis, disc herniation, degenerative disc disease, or degenerative spondylolisthesis) and those with complete one-year follow-up questionnaires were included. Patients treated for thoracic or cervical pathologies and non-elective lumbar conditions were excluded. There were 6971 eligible patients. A total of 5389 patients who underwent surgery and completed one-year follow-up questionnaires were included. Patients’ socio-demographics, lifestyle, health status, and clinical factors were examined. The primary outcome was the association between expectation fulfillment and preoperative patient factors, estimated with ordinal logistic regression models. Results: The mean age of the participants was 59.5 years, with 49.8% (2683) of them being females. Unmet expectations ranged from 6.7% to 25.7%, with improvement in general physical capacity being the most important expectation fulfilled from surgery for 20% of patients. Factors such as longer symptom duration (OR:0.74; 95% CI:0.63-0.86), previous lumbar spine surgery (OR:0.63; 95% CI:0.46, 0.89), and reoperations (OR:0.36; 95% CI:0.2, 0.63) were associated with higher unmet expectations in the leg pain reduction dimension. Similar results were noted across all other expectation dimensions. Conclusion: Identifying patients before surgery who are at risk of unmet expectation fulfilment provides an opportunity for intervention during presurgical consultations.

ID: 2051

A135: Examining the impact of successive revision spine surgeries on pain, disability, mental health, satisfaction, and length of stay: a Canadian Spine Outcomes and Research Network (CSORN) study

Sufyan Faridi ^1,2 , Erin Bigney ^2,3 , Jeffrey Hebert ^4,5 , Neil Manson ^2,6,7,8 , Edward Abraham ^2,3,8,9 , Chris Small ^2,6,8,10 , Eden Richardson ^2,3,11 , Rory McPhee ^2,12 , Jill Kearney ^2,3 , Najmedden Attabib ^2,7,13

¹ Dalhousie Medicine New Brunswick, Faculty of Medicine, Saint John, Canada,

² Canada East Spine Centre, Saint John, Canada,

³ Horizon Health Network, Saint John, Canada,

⁴ University of New Brunswick, Faculty of Kinesiology, Fredericton, Canada,

⁵ Murdoch University, School of Psychology and Exercise Science, Perth, Australia,

⁶ Horizon Health Network, Division of Orthopaedic Surgery, Zone 2, Saint John, Canada,

⁷ Dalhousie University, Faculty of Medicine, Halifax, Canada,

⁸ Saint John Orthopaedics, Saint John, Canada,

⁹ Dalhousie Medicine New Brunswick, Department of Surgery, Saint John, Canada,

¹⁰ Dalhousie Medicine New Brunswick, Saint John, Canada,

¹¹ Canadian Spine Outcomes and Research Network, Markham, Canada,

¹² University of New Brunswick, Saint John, Canada,

¹³ Horizon Health Network, Division of Neurosurgery, Zone 2, Saint John, Canada

Background: Patients undergoing spine surgery frequently require revision procedures, which are more complex and often result in poor outcomes compared to primary surgery. However, the specific impacts of successive revision surgeries are underexplored. Hypothesis/Objective: To estimate the rates of revision and succussive revision spine surgeries in Canada and compare outcomes among patients undergoing primary surgery, 1-revision surgery, and 2 or more revision spine surgeries. Methods: This retrospective cohort study utilized data from a national database collected preoperatively, and 3- and 12-months post-surgery. Patients who underwent thoracolumbar surgery for degenerative conditions were categorized into primary, 1-revision, or 2+ revision cohorts. Outcomes included Numeric Rating Scales (NRS) for leg and back pain, Oswestry Disability Index (ODI), Mental Health Component Score of the SF-12 (MCS), patient satisfaction, and length of stay. Linear mixed-models controlled for age, sex, education, smoking, comorbidities, and number of surgical levels. Model results were reported with difference scores (DS) and 95% confidence intervals. Results: Among 6,068 patients, 9.8% underwent revision, and 1.1% underwent 2 or more revision surgeries. All cohorts showed significant improvement in NRS-leg pain, NRS-back pain, and ODI. Compared to the 1-revision cohort, the 2+ revision cohort demonstrated greater NRS-leg pain at 3- (DS = 1.33[0.71 to 0.69]) and 12-months (DS= 1.35[0.69 to 2.01]), NRS-back pain at 3- (DS = 0.92[0.36 to 1.48]) and 12-months (ds = 0.93[0.34 to 1.51]), and ODI at 3- (ds = 9.24[5.29 to 13.18) and 12-months (DS = 10.16[6.02 to 14.28]). The 2+ revision cohort also demonstrated greater NRS-leg pain at 3- (DS = 2.06[1.47 to 2.66]) and 12-months (DS= 2.19[1.56 to 2.82]), NRS-back pain at 3- (DS= 1.58[1.04 to 2.11) and 12-months (DS = 1.77[1.22 to 2.33]), and ODI at 3- (DS= 16.60[12.84 to 20.37]) and 12-months (DS= 18.36[14.42 to 22.29]) compared to the primary cohort. Two or more revision patients had worse baseline MCS scores compared to the 1-revision (DS = -13.45[-16.02 to -10.88]) and primary (ds = -13.71[-16.18 to -11.24) cohorts but improved from baseline to 3- (DS= 10.44[7.78 to 13.10]) and 12-months (DS= 15.70[12.90 to 18.51]). Most patients in all subgroups were satisfied with their surgery: 2+ revision3 months = 72%, 12 months = 65%; 1-revision 3 months = 81%, 12 months = 76%; primary 3 months = 89%, 12 months= 87%. Two or more revision (mean = 7.0 [4.61 to 9.33) and 1-revision (mean = 4.90 [4.19 to 5.60]) cohorts had longer hospital stays compared to the primary cohort (mean = 3.44[3.11 to 3.78]). Discussion: Patients who underwent 2 or more revision surgeries experience large postoperative improvements in mental health., indeed their mean baseline MCS scores indicated severe psychological distress which rise to having post-operative scores on par with those seen in the general population. Patients who underwent 2 or more revision surgeries also had reduced pain and disability, though less than patients undergoing a single revision or primary surgery. Patients who underwent two or more surgeries were also less satisfied with their surgery at 1-year. This information can aid in expectation management and shared surgical decision-making.

OP16: Adolescent Spinal Deformity 1

ID: 536

A136: Limited fusion for congenital scoliosis: is it truly one and done?

Brandon Yoshida ¹ , Tyler Tetreault ² , Luke Drake ³ , Tiffany Phan ² , Jacquelyn Valenzuela-Moss ² , Tishya Wren ² , Lindsay Andras ² , Michael Heffernan ²

¹ University of Southern California, Keck School of Medicine, Los Angeles, United States,

² Children's Hospital Los Angeles, Los Angeles, United States,

³ University of Mississippi Medical Center, Jackson, United States

Introduction: Limited spinal fusion is a common surgical strategy in the treatment of congenital scoliosis. Due to the heterogeneity of deformity and treatment strategies, long term outcomes, including the need for additional surgery, are poorly understood. The purpose of the study was to understand the rate and risk factors for reoperation following limited fusion for congenital scoliosis. Methods: Congenital scoliosis patients initially treated with a limited instrumented fusion at a tertiary pediatric medical center were reviewed for clinical and radiographic data. Curve progression, complications, and the surgical details were compared between patients who underwent additional surgery and patients who did not require additional surgery. Risk factors for reoperation were compared between groups. Results: 35 patients underwent limited instrumented fusion at an average age of 4.9 years (SD: 2.5). The mean number of levels fused was 3.5 (SD: 1.3). Index surgery location included: thoracic (46%), thoracolumbar (31%), lumbar (17%), and lumbosacral (6%). Average follow-up was 7.6 years (range: 2.2-14.1, SD: 3.4). Average curve magnitude improved from 51° to 30°, with a mean improvement of 21° (range: 11° to 50°, SD: 15°, p = 0.002). Eighteen patients (51%) required reoperation at a mean of 5.2 years, with a mean of 1.8 (SD: 3.0) additional surgeries. Preoperative curve magnitude was greater in patients who had reoperation compared to patients who did not require reoperation (66.7 ± 20.3 vs 34.2 ± 6.7, p < 0.001). Pre-operative curves ≥ 45° had a 94% (17/18) reoperation rate compared to only 6% (1/17) in curves < 45°, odds ratio of 272 (95% CI: [15.7,4724.2], p < 0.0001). Additionally, constructs that did not span the upper and lower end vertebrae were associated with the need for additional surgery (p = 0.04). Age at index surgery, medical comorbidities, addressing all congenital anomalies during index procedure, number of levels fused, and location did not differ between groups. Conclusion: Limited fusion for congenital scoliosis resulted in a 51% reoperation rate at a mean of 5.2 years. The results suggest that limited fusion should be considered prior to the curve reaching 45º and instrumentation should span the deformity to minimize the need for reoperation.

ID: 2897

A137: The impact of patient age on surgical outcomes in adolescent idiopathic scoliosis: a comprehensive analysis

Ji Uk Choi ¹ , Dong-Ho Lee ¹ , Chang Ju Hwang ¹

¹ Asan medical center, Orthopaedics, Seoul, South Korea

Introduction: Optimal timing of surgical intervention in adolescent idiopathic scoliosis (AIS) is crucial to achieving favorable outcomes. Early surgery is often recommended for skeletally immature patients with curves exceeding 45-50°, as it can prevent curve progression and reduce the need for more extensive procedures. However, patients and families frequently delay surgery due to concerns about complications, postoperative pain, and academic or social disruptions. While existing studies compare outcomes between adolescence and adulthood, there is a gap in understanding the impact of age within the adolescent period on surgical outcomes. Material and Methods: This retrospective cohort study included 168 AIS patients who underwent posterior spinal fusion with pedicle screw instrumentation between 2012 and 2020. Patients were divided into two groups based on age at surgery: those younger than 14 years (Y-14, n = 37) and those aged 14 years or older (O-14, n = 131). Preoperative, postoperative, and follow-up radiographs were analyzed for curve correction and flexibility, and clinical outcomes were assessed using the SRS-22 questionnaire. Statistical comparisons were made between groups using paired t-tests, chi-square tests, and multivariable regression analysis. Results: The Y-14 group presented with larger main thoracic curves preoperatively but demonstrated superior correction rates immediately postoperatively and at two years (83.25% vs. 77.49%, p < 0.001). Age was a significant predictor of curve correction, with younger patients achieving better outcomes. Despite these radiographic differences, clinical outcomes, as measured by SRS-22 scores, were similar between the groups at two years. Complication rates were low and comparable across both groups. Conclusion: Early surgical intervention in AIS patients is associated with better radiographic outcomes, likely due to increased spinal flexibility in younger patients. Although health-related quality of life improvements are comparable regardless of age, early surgery may offer enhanced correction and reduced risks of complications. This study highlights the importance of considering patient age when planning AIS surgery to maximize clinical and radiographic outcomes. Future research should focus on long-term effects of surgical timing within adolescence.

ID: 346

A138: The use of Ghurki Halopelvic Traction (GHT) for severe scoliosis and other spinal deformities. A preliminary report

Mutaleeb Shobode ¹ , Gbadebo Ibraheem ² , Lukman Ajiboye ³ , Misbahu Ahmad ⁴ , Omolola Fagbohun ⁵ , Oladapo Ekundayo ⁶ , Bolarinwa Akinola ⁷ , John Onuminya ⁸ , Adetunji Toluse ⁹ , Taofeek Adeyemi ⁹ , Babatunde A. Osundina ⁹ , Ganiyu Aremu ¹⁰ , Mohammed Salihu ¹¹ , Adeleke Abiodun ¹²

¹ Nationwide Children's Hospital, Department of Orthopaedics, Clinical Research, Columbus, Ohio, United States,

² University of Ilorin Teaching Hospital, Department of Orthopaedics, Kwara, Nigeria,

³ Usmanu Dan Fodiyo University Sokoto, Department of Orthopaedics, Sokoto, Nigeria,

⁴ Aminu Kano Teaching Hospital, Department of Surgery, Kano, Nigeria,

⁵ Lagos State University Teaching Hospital, Department of Anaesthesia, Lagos, Nigeria,

⁶ University of Alberta, Division of Surgery, Edmonton, Canada,

⁷ Osteon Clinics, Orthopaedics, Lagos, Nigeria,

⁸ Irrhua Specialist Hospital, Department of Orthopaedics, Edo, Nigeria,

⁹ National Orthopaedic Hospital Lagos, Orthopaedics, Lagos, Nigeria,

¹⁰ Federal Medical Center Abuja, Orthopaedics, Abuja, Nigeria,

¹¹ University of Abuja Teaching Hospital Gwagwalada, Department of Orthopaedics, Abuja, Nigeria,

¹² Obafemi Awolowo University Teaching Hospital Ife, Department of Orthopaedics, Osun, Nigeria

Introduction: Severe spinal deformities including scoliosis with bending Cobb’s above 90⁰ are often very rigid and often difficult to achieve good correction with higher risk of complications. Late presentation is common in this part of the world with attendant rigid deformities. Different measures have been described and used to make this curves less rigid and easier to handle including the Ghurki Halopelvic Traction, GHT. Objective: To describe the use and versatility of the GHT in treatment of severe and rigid spine deformities. Materials and Methods: Forty five (56) patients that met the inclusion criteria were offered the GHT between July 2022 and 2024. Seven of these patients are still on traction and awaiting definitive spinal fusion and so are not included in this cohort. Patients’ demographics, Clinico-epidemiological data and deformity characteristics were recorded. There were two patients with thoracic and thoracolumbar kyphotic deformities and the remaining 47 had severe and rigid scoliosis curves (8 were EOS). All the patients were evaluated with plain radiographs, CT scan, an MRI scan and pulmonary function test. All the patients were counselled about the device, the intended use and a clinical psychologist was on hand to mentally prepare the patients for the procedure. Patients with EOS had traction for 4 weeks while others were maintained for an average of 7 weeks. Post-operative plain radiograph was taken immediate post traction and before definitive spinal fusion/non-fusion surgeries (in the case of EOS). SPSS version 17 software was used to analyze the data. Results: The patients were aged 4 to 28 years. There were 39 females and 10 males with a mean bending Cobb’s magnitude of 92⁰. All had over 60 percent correction of the coronal cobb’s magnitude at the time of definitive spinal fusion. There was also significant correction of apical vertebral translation. Two patients had traction aborted at 5 and 6 weeks after they choked on their meals. Pin tract infection, halo breakage, neck and pelvic pain were more common complications. Conclusions: The GHT is a good device for treating severe spinal deformities particularly in resource poor countries where patients can’t be admitted for too long as obtained with halo-gravity traction. It is versatile, easy to construct, gives better correction of coronal and sagittal imbalance, causes minimal disruption of activities of daily living but may require more supervision than the halo-gravity traction.

Keywords: GHT, Severe spinal deformities, Scoliosis, kyphosis, Cobb’s angle.

ID: 828

A139: Surgical technique comparison between high-density pedicle screw instrumentation and high-density instrumentation with sublaminar clamp in adolescent idiopathic scoliosis

Angelo Toscano ¹ , Elena Mendola ¹ , Fabrizio Perna ¹

¹ IRCCS Istituto Ortopedico Rizzoli, Ortopedia Generale, Dipartimento Rizzoli Sicilia, Bologna, Italy

Introduction: The surgical corrective techniques for adolescent idiopathic scoliosis (AIS) must include a triplanar correction in order to obtain a balanced spine with the least possible functional sacrifice. Hypokyphosis is the most common sagittal plane variance in patients with AIS and it represents the most influential parameter in long-term results. The aim of this work is to compare the radiographic and clinical results obtained using two different surgical techniques for AIS correction and to identify the best technique for sagittal plane correction capacity. Material and Methods: We conducted a retrospective analysis on 70 patients treated with two different techniques: correction by translation and derotation with asymmetrical rods using high density pedicle screws (group A - 54 patients) and correction by translation and derotation with asymmetrical rods, high density pedicle screws and sub-laminar clamps (group B - 16 patients). The postoperative radiographic and clinical results were compared with the preoperative values and between the two techniques. Results: The average follow-up was 8 months (1-36 months). The median preoperative Risser sign in group A was IV, while in group B was III. The mean value of the preoperative Cobb angle was 61.8° ± 15.5° in group A and 68.5° ± 11.57° in group B. The mean postoperative value was respectively 19.14 ± 9.23° in group A with a statistical difference between pre and post (p < 0.01) and 20.56 ± 8.35° in group B (p = 0.21). The mean preoperative value of thoracic kyphosis was 23.83 ± 12.72° in group A and 25.93° ± 10.8 in group B. The mean postoperative kyphosis value was 28.03 ± 8.14° in group A and 30.5 ± 9.2° in group B with a statistical difference in both groups between the pre and postoperative values (p < 0.01). Nevertheless, we couldn’t find any statistical differences regarding the postoperative changes in Cobb angle (p = 0.28) and the post operative changes in thoracic kyphosis angle (p = 0.34) while confronting simultaneously the two groups. Neither sagittal nor coronal balance has undergone significant postoperative changes. There were no major perioperative complications. Two minor perioperative complications were recorded in group A. At the last available follow-up, no screws pull-out, non-union or deformity progression were recorded. Conclusion: Both surgical techniques showed good deformity correction in the three spatial planes with excellent radiological results and a low complication rate. However, up to this point of follow up, our study has shown no statistical differences between the two groups in terms of frontal and sagittal correction and no evidence that one technique is better than the other. The authors suggest the need of further studies to analyse both techniques and their results on the sagittal plane.

ID: 617

A140: What happens when you wait? Larger curves require more resources for less correction in neuromuscular scoliosis

Brandon Yoshida ¹ , Jacquelyn Valenzuela-Moss ² , Tyler Tetreault ² , Tishya Wren ² , Tiffany Phan ² , Lindsay Andras ² , Michael Heffernan ²

¹ University of Southern California, Keck School of Medicine, Los Angeles, United States,

² Children's Hospital Los Angeles, Los Angeles, United States

Introduction: Despite previous attempts to assess the impact of curve magnitude on outcomes after posterior spinal fusion (PSF) in neuromuscular scoliosis (NMS), equipoise remains regarding optimal surgical timing. This study assessed the impact of curve magnitude on the complexity of surgery, resources utilized, and outcomes during surgical management of NMS. Methods: Consecutive patients aged 7-21 years with NMS and fusion to the pelvis were reviewed at a single tertiary pediatric hospital. Patient demographics, surgical parameters, complications, and radiographic measurements were collected. Clinical and radiographic outcomes were compared between patients with preoperative curves ≥ 80° and < 80°. Results: 337 patients met inclusion criteria with a mean curve of 83.1° ± 26.5°. Patients with curves ≥ 80° had greater blood loss (994 ± 607 vs 764 ± 535 ml, p = 0.0003), increased transfusion requirement (795 ± 647 vs 478 ± 482 ml, p < 0.0001), had longer surgical time (418 ± 117 vs 338 ± 117 min, p < 0.0001) anesthesia time (552 ± 123 vs 472 ± 122 min, p < 0.0001), and ICU stay (3 ± 2 vs 2 ± 1 day, p = 0.009) compared to patients with curves < 80°. Need for continued intubation was 2.4 times more likely (OR 2.4; 95% CI [1.5, 3.9]; p = 0.0002) and the odds of utilizing adjunctive surgical techniques (i.e. intraoperative halo traction, temporary rods, and/or staged procedures) were 4 times more likely for patients with curves ≥ 80° (OR 4.1; 95% CI [2.5, 6.6]; p < 0.0001). The use of spinal osteotomies was more likely among patients with larger curves (OR 4.6; 95% CI [2.8, 7.2]; p < 0.0001). 75% of unplanned staging occurred in the ≥ 80° group. Residual curve magnitude (44.7 ± 20.5 vs 22.6 ± 13.6, p < 0.0001) and pelvic obliquity (10.2 ± 12 .6 vs 4.8 ± 8.7, p < 0.0001) were higher in the ≥ 80° group. Complications were similar between groups (p = 0.81). Conclusion Curve magnitude ≥ 80° was associated with larger residual curves despite increased surgical complexity and greater resource utilization in the management of NMS, which parents and providers should consider when deciding on timing of surgical intervention.

ID: 1691

A141: Trends and outcomes in adolescent idiopathic scoliosis surgery: a nationwide analysis of improvements from 2010 to 2022

William Karakash ¹ , Henry Avetisian ² , Maya Abu-Zahra ¹ , Justin Zheng ¹ , Jeffrey C. Wang ¹ , Raymond Hah ¹ , R. Kiran Alluri ¹ , Daniel Rusu ¹

¹ Keck School of Medicine of USC, Los Angeles, United States,

² Jacobs School of Medicine, Buffalo, United States

Introduction: Surgical correction of adolescent idiopathic scoliosis (AIS) involves complex multilevel spinal fusion to restore three-dimensional spinal alignment, reduce deformity, and halt curve progression. These interventions are associated with prolonged operative times, substantial complication rates, and inter-surgeon variability. Advancements in implant technology, instrumentation, intraoperative monitoring, and spinal biomechanics have contributed to improved procedural safety. This study utilizes a large national database to evaluate trends in AIS operative management and post-operative outcomes in the United States, aiming to elucidate the evolving landscape of surgical interventions for this condition. Methods: A retrospective analysis was conducted using the PearlDiver Mariner database to identify patients with AIS who underwent multilevel posterior spinal fusion between 2010-2022. Data were extracted using ICD-9, ICD-10, and CPT codes for relevant diagnoses and procedures. Exclusion criteria encompassed patients younger than 10 or older than 18 years, as well as those with malignancy, infection, or trauma. Temporal trends were assessed by comparing outcomes between two time periods: 2010-2015 and 2016-2022. Statistical analyses included student’s t-tests and chi-squared analyses for continuous and categorical data, respectively. Results: The study analyzed 17,541 AIS patients who underwent multilevel posterior spinal fusion (9,174 in 2010-2015; 8,367 in 2016-2022). The average age remained consistent (14.5 ± 2.0 years, p = 0.94), while the Elixhauser Comorbidity Index (ECI) increased (1.0 ± 1.3 to 1.3 ± 1.4, p < 0.001) and hospital stay decreased (5.0 ± 3.1 to 4.1 ± 3.0 days, p < 0.001). Two-year revision rates declined (4.9% to 3.4%, p < 0.001), with reductions in incision and drainage and debridement procedures (3.2% to 2.1%, p < 0.001) and instrument removal (2.2% to 1.4%, p < 0.001). Surgical advancements showed increased use of computer navigation (5.4% to 15.5%, p < 0.001), robotics (0.3% to 1.3%, p < 0.001), and Smith-Peterson osteotomies (23.1% to 32.6%, p < 0.001). All-cause readmissions decreased at 30 days (6.7% to 4.0%, p < 0.001) and 90 days (7.5% to 4.6%, p < 0.001). Thirty-day surgical complications decreased (4.5% to 2.1%, p < 0.001), with a notable reduction in surgical site infections (2.7% to 0.6%, p < 0.001). Aggregate medical complications within 30 days also decreased (10.4% to 6.0%, p < 0.001), with reductions in post-operative infections, anemia, transfusions, and pneumonia (all p ≤ 0.01). Conclusion: This nationwide analysis reveals significant improvements in AIS surgical outcomes from 2010-2015 to 2016-2022. There were notable reductions in hospital stay, revision rates, readmissions, and both surgical and medical complications. The adoption of advanced techniques such as computer navigation, robotics, and Smith-Peterson osteotomies likely contributed to these improvements. Additionally, enhanced infection control measures have led to a decrease in surgical site infections and debridement procedures. These trends suggest that ongoing technological advancements and refined surgical techniques are improving the safety and efficacy of AIS interventions. Future research should explore long-term outcomes and the cost-effectiveness of these innovations to further optimize AIS management.

ID: 2101

A142: Comparative analysis of correcting larger adolescent kyphoscoliotic deformity with HPT and final fusion vs without HPT fusion only

Sabir Khan Khattak ¹

¹ Ghurki Trust & Teaching Hospital, Orthopedic and Spine Center, Lahore, Pakistan

Introduction: Idiopathic rigid decompensated kyphoscoliosis is a severe spinal deformity tending to progress without surgical treatment. Surgical management methods include the posterior, anterior, and combined anterior–posterior approaches with risk of complication. Halopelvic traction (HPT) is one of the procedure that gradually correct the deformity upto some extent and reduce the risk of complication in such patient.Material and Methods: This retrospective non randomized study was conducted on 79 patients meeting the inclusion criteria at the Department of Orthopedics & Spine Centre, Ghurki Trust Teaching Hospital, Lahore. All those patient who had large rigid curve with less than 15-degree correction on fulcrum radiograph was included. These patient was divided into 2 groups, one was treated with initial HPT for 6 weeks and gradual correction of deformity with later final fusion and 2^nd group was treated with fusion only without HPT. We measured postoperative Cobbs angle as deformity correction parameter in both group, as well as intraoperative neuromonitoring data loss, intraoperative bleeding and other postoperative complication. Results: In cohort of 79 kyphoscoliotic deformity patients, HPT and final fusion (group A) had 39 patients while without HPT final fusion (group B) had 40 patients. The gender distribution showed that Group A had a higher proportion of males (51.3%) compared to Group B (32.5%), while Group B had a higher proportion of females (67.5%) compared to Group A (48.7%). The mean age of patients in Group A was 15.62 years, significantly higher than the mean age of 14.33 years in Group B (p < 0.001). Pre-operatively, Cobb’s angle on the anteroposterior (AP) view was significantly higher in Group A (106.36°) compared to Group B (90.15°) with a p-value of 0.001. Similarly, post-operatively, Cobb’s angle on the AP view is almost comparable in Group A (27.77°) & Group B (24.80°) (p = 0.001). There was no intraoperative neuromonitoring data loss in group A while group B had data loss in 5 patients with 3 recovered intraoperatively. There was 1 postop mortality in group B and more ICU stay. Conclusion: In rigid larger adolescent kyphoscoliotic deformity, initial HPT for 6 weeks with gradual correction of deformity with traction and later final fusion shows good results in term of deformity correction and neurology loss than only fusion in such cases.

ID: 2584

A143: Schroth physiotherapeutic scoliosis-specific exercises does not improve bracing outcomes in adolescent idiopathic scoliosis - results from an assessor, statistician and investigator-blinded randomised clinical trial

Lee Yin Goh ¹ , Kenny Yat Hong Kwan ¹ , Aldous Cheng ²

¹ The University of Hong Kong, Hong Kong, Hong Kong,

² Duchess of Kent Children's Hospital, Hong Kong, Hong Kong

Introduction: Bracing is the most effective non-operative treatment for adolescent idiopathic scoliosis that are at risk of progression in skeletally immature patients, but treatment failure remains high. Schroth physiotherapeutic scoliosis-specific exercises (PSSE) has been shown to reduce curve progression rates but the lack of robust evidence prevents recommendation for its routine use. The objective of this study was to evaluate the effect of Schroth PSSE on curve progression in AIS patients during bracing compared with bracing alone until skeletal maturity. Material and Methods: We conducted a single centre, prospective, assessor, statistician and investigator-blinded randomized clinical trial (NCT03305185) on consecutive AIS patients who met the Scoliosis Research Society (SRS) criteria for bracing. 105 patients were randomly assigned to Schroth PSSE and bracing (Experimental group) compared to bracing alone (Control group) and followed up until skeletal maturity. All patients were prescribed an underarm brace and instructed to wear the brace at least 18 hours per day. The intervention consisted of a 45minute daily outpatient-based Schroth PSSE home program with 3-monthly supervised sessions. The primary outcome was curve progression of 6^o or more, and the secondary outcomes were change in Cobb angles, curve progression to 50^o or more, change in sagittal and axial parameters, and change in patient-related outcome scores at skeletal maturity. Results: 96 patients completed the study. At baseline, there were no statistical significant differences in age, gender, BMI, cobb angle, curve type, and skeletal maturity between the 2 groups. Mean follow up was 36 months. Brace wear compliance was similar between the 2 groups. Schroth compliance was 4.27 days per week, 89.5% attendance rate, with objective score of 81% by therapist. At skeletal maturity, there was no difference between the 2 groups in the proportion of patients who progressed (23.5 vs 31.1%) and those who improved or remained unchanged (76.5 vs 68.9%) (p = 0.4918). Mean Cobb angles were similar between the 2 groups (30.8 vs 33.4deg, p > 0.05). There was no difference in the proportion of patients who reached the surgical threshold (9.8 vs 13.3%, p = 0.75). No statistically significant difference was found in thoracic kyphosis, lumbar lordosis, angle of trunk rotation, self image scores or EQ-5D-5L between the 2 groups. Conclusion: Schroth PSSE added to bracing did not improve bracing outcomes in AIS patients who are at risk of curve progression. Routine use of Schroth PSSE during bracing is not recommended in this group of patients.

ID: 1374

A144: Determination of lowest instrumented vertebra using “Nanjing Rule” achieved shorter fusion safely compared with “LSTV Rule” for adolescent idiopathic scoliosis with Lenke 1A curves

Xiaodong Qin ¹ , Yi Chen ¹ , Zhong He ¹ , Dong Xie ² , Zhen Liu ¹ , Yong Qiu ¹ , Zezhang Zhu ¹

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

² Nanjing Drum Tower Hospital Clinical College of Jiangsu University, Division of Spine Surgery, Department of Orthopedic Surgery, Nanjing, China

Introduction: Posterior selective thoracic fusion is the mainstream surgical approach for adolescent idiopathic scoliosis (AIS) with Lenke 1A curves. However, it keeps controversial regarding the choice of the lowest instrumented vertebra (LIV). Lenke et al. proposed the “last substantially touching vertebra (LSTV) Rule”, suggesting that LIV should be the last vertebra substantially touched by the central sacral vertical line (CSVL). Meanwhile, our group developed a set of LIV selection criteria known as the “Nanjing Rule.” This study aims to compare the clinical outcomes of these two LIV selection rules. Material and Methods: The “Nanjing Rule” was defined as follows: when Risser ≥ 3, main curve length ≤ 8 segments, LSTV-1 rotation ≤ I°, LSTV-1 deviation from the CSVL < 20mm, preoperative coronal balance < 10mm, and the intervertebral disc between LSTV-1 and LSTV opens bidirectionally on bending films, the LIV can be selected as LSTV-1; if these conditions are not met, LIV should be selected as LSTV. A prospective consecutive collection of 120 Lenke 1A cases who underwent posterior spinal fusion surgery were enrolled. Patients with odd numbers were guided by the “LSTV Rule,” while those with even numbers followed the “Nanjing Rule”. The duration of follow-up was at least two years. Imaging parameters were measured at the final follow-up, and a comparison was made between the two groups. Results: The average duration of follow-up was 33.1 ± 6.3 months for the “LSTV Rule” group and 32.8 ± 7.5 months for the “Nanjing Rule” group. At the last follow-up, the incidence of distal adding-on phenomenon was 15.0% in the “LSTV Rule” group and 16.7% in the “Nanjing Rule” group, with no significant difference between the two groups. The main curve correction rates were 74.8 ± 10.5% and 73.2 ± 12.3%, respectively, with no significant difference. The “LSTV Rule” group had an average fused segment of 10.5 ± 1.7, while the “Nanjing Rule” group was significantly lower at 9.7 ± 1.5 segments (p = 0.003). Additionally, the LIV in the “Nanjing Rule” group was on average at the T12-L1 level, whereas in the “LSTV Rule” group, it was at the L1-L2 level (p = 0.004). Conclusion: For Lenke 1A patients, both the “Nanjing Rule” and the “LSTV Rule” for guiding LIV selection can achieve satisfactory correction outcomes. There is no significant difference in the incidence of complications such as distal adding-on phenomenon between the two approaches. Choosing LIV based on the “Nanjing Rule” allows for the preservation of distal fusion segments and demonstrates better clinical applicability.

OP17: Spine Trauma Surgical 2

ID: 2299

A145: Early surgery improves neurological, functional, and quality of life outcomes in acute traumatic spinal cord injury: a global endpoint analysis of 470 patients from the spine trauma study group (STSG) prospective cohort

Michael Fehlings ^1,2 , Karlo Pedro ¹ , Mohammed Ali Alvi ¹ , Jefferson Wilson ¹ , Kevin Thorpe ¹ , Alexander Vaccaro ³ , Bizhan Aarabi ⁴

¹ University of Toronto, Toronto, Canada,

² University Health Network, Toronto, Canada,

³ Thomas Jefferson University, Philadelphia, United States,

⁴ University of Maryland, Baltimore, United States

Introduction: Despite the advocacy of the STASCIS study for early surgery (< 24 hrs) after spinal cord injury (SCI) for over a decade, the optimal timing for surgical intervention remains controversial. Recent studies reveal significant heterogeneity in research findings, including varied time cut-offs, differing degrees of spinal decompression, and the use of insensitive outcome measures. While neurological improvement remains the primary focus of SCI trials, this metric alone does not fully capture the spectrum of clinically meaningful recovery post-injury. Incorporating a wide range of patient-reported outcomes allows for a more comprehensive evaluation and enhances the ability to detect treatment effects within the diverse SCI population. Materials and Methods: We reanalyzed data from the prospective cohort of the Spine Trauma Study Group (STSG), which enrolled adult SCI patients from 2002-2009. To assess outcomes, we utilized a guideline-compliant composite endpoint that integrates three outcome measures: Total Motor score (TOTM), Functional Independence Measure (FIM), and Short Form-36 Health Survey (SF-36), all measured at one-year post-surgery. We employed the Global Statistical Test (GST) to determine whether early surgery (< 24 hrs) resulted in overall improvement across these three endpoints. The analysis was conducted on the full study cohort and replicated using a covariate-adjusted cohort matched by propensity scores for age, etiology, and baseline neurological and functional status. We calculated the Global Treatment Effect (GTE) to summarize the treatment effect size, with a GTE greater than 0 indicating a global treatment benefit. Results: The study included a total of 470 patients in the complete cohort (mean age: 47.86 years, 25.1% females) and 340 patients in the propensity score-matched group. Among these, 247 and 223 patients received early surgical decompression (< 24 hours) and late surgical decompression, respectively. In the unadjusted complete case analysis, early surgery was associated with a significantly higher rank sum across all three endpoints compared to late surgery [Median rank sum (IQR) 729.0 (544.8, 910.8) vs 678.5 (500.2, 848.0), p = 0.01]. The propensity-score matched analysis yielded similar higher rank sum favoring early surgery [Median rank sum (IQR) 523.2 (401.1, 656.4) vs 497.0 (348.9, 622.1), p = 0.04]. Consistent GTEs were observed in both unadjusted (GTE = 0.08, 95% CI 0.02, 0.12) and adjusted analysis (GTE = 0.08, 95% CI 0.003, 0.15), indicating a 54% [=(1+GTE)/2] higher probability of global improvement with early surgery. The GST demonstrated the highest statistical power among the multivariable testing methods and required a smaller sample size compared to conventional parametric tests. Conclusion: Early surgery (< 24 hrs) after traumatic SCI is associated with concurrent global improvement in motor, functional, and quality of life domains at one year. This analysis reinforces the findings of the STASCIS trial, providing robust evidence for the benefits of timely surgical decompression and supporting GST as an efficient trial methodology encompassing multidimensional outcome scales.

ID: 1506

A146: What drives clinic follow-up after traumatic spinal injury? An observational cohort study from Tanzania

Chibuikem Ikwuegbuenyi ^1,2 , Julie Woodfield ^2,3 , Romani Roman Sabas ² , Magalie Cadieux ^2,4 , Scott Lawrence Zuckerman ^5,6 , Francois Waterkeyn ⁷ , Noah Willett ¹ , Halinder Mangat ⁸ , Hamisi Shabani ² , Roger Härtl ¹

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

² Muhimbili Orthopedic and Neurosurgery Institute, Division of Neurosurgery, Dar es Salam, Tanzania,

³ Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom,

⁴ Washington University School of Medicine in St Louis, Neurological Surgery, St Louis , United States,

⁵ Vanderbilt University Medical Center, Neurological Surgery, Nashville, United States,

⁶ Vanderbilt University Medical Center, Orthopedic Surgery, Nashville, United States,

⁷ Grand Hôpital de Charleroi, Department of Neurosciences, Charleroi, Belgium,

⁸ Kansas University Medical Center, Department of Neurology, Kansas City, United States

Introduction: Traumatic spinal injuries (TSI) are a significant health concern in low- and middle-income countries (LMICs), where access to resources is limited. Clinic visits are crucial for monitoring recovery and improving outcomes in TSI patients, yet factors influencing clinic attendance in LMICs remain under-researched. This study aims to identify the sociodemographic, injury-related, and hospital factors that drive clinic visits among TSI patients treated at Muhimbili Orthopaedic Institute (MOI), Tanzania. Material and Methods: This retrospective cohort study utilized data from a neurotrauma registry at MOI. The study included patients admitted with TSI between September 2016 and October 2021. Eligible patients were adults (≥ 14 years) with isolated TSI or TSI with mild traumatic brain injury (TBI). Data on demographics, injury characteristics, and hospital parameters were extracted from the registry, while clinic visit attendance was identified on the electronic medical record system. Follow-up attendance was tracked for up to at least one-year post-discharge. Logistic regression models were used to identify factors associated with return to the clinic, and Kaplan-Meier survival analysis was used to evaluate time to loss of follow-up. Results: Out of 477 patients, 250 (52.4%) returned for clinic follow-up, with a median age of 34 years (IQR: 27-42) and a predominantly male (410/477, 86%) cohort. Factors independently associated with increased odds of return to the clinic included patients with private insurance (adjusted OR 2.69, 95% CI 1.38-5.45, p = 0.005), patients involved in an RTA (adjusted OR 2.15, 95% CI 1.22-3.83, p = 0.009), patients with lumbar injuries (adjusted OR 2.26, 95% CI 1.30-4.00, p = 0.004), and patients with improved AIS scores at discharge (adjusted OR 3.52, 95% CI 1.72-7.64, p = 0.001). Longer hospital stays decreased return likelihood (adjusted OR 0.62, 95% CI 0.40-0.93, p = 0.022). Of returners, 63/250 (25.2%) completed one year of follow-up. AIS B-D at admission increased the odds of completing 1-year clinic visits (adjusted OR 2.49, 95% CI 1.10-6.00, p = 0.034), while the male patients had decreased odds (adjusted OR 0.21, 95% CI 0.09-0.43, p < 0.001). Kaplan-Meier analysis showed that 50% of patients were lost to follow-up within 14 days, with fewer than 13% remaining by one year. Conclusion: Several factors influence follow-up attendance after TSI in Tanzania, including private insurance, injury mechanism, neurological improvement, and gender. However, the high rate of loss to follow-up, with only 25% completing one year of clinic visits, underscores the challenges of maintaining long-term follow-up in LMICs. Addressing both patient-specific and systemic barriers to follow-up care is critical for improving outcomes in spine trauma patients in resource-limited settings. These findings highlight the need for targeted interventions to enhance follow-up rates and reduce the long-term burden of disability in LMICs.

ID: 2407

A147: Characteristics of mortality versus survivors in major trauma injuries associated with spinal fractures in an urban level 1 trauma centre

Shruthi Atapaka ¹ , Zion Hwang ² , Hasan Raza ² , Charles Taylor ² , Adnan Sheikh ² , James Geddes ² , Timothy Bishop ² , Jason Bernard ² , Rhys Owen ¹ , Deepshika Varasala ¹ , Mak Macapagal ¹ , Jack Williams ¹ , Darren Lui ²

¹ St. George's, University of London, London, United Kingdom,

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

Introduction: Spinal trauma poses significant challenges for major trauma centres, leading to high complication and mortality rates. Key factors influencing patient outcomes include injury severity, co-morbidities, and polytrauma. This retrospective study examines differences between survivors and non-survivors at an urban Level 1 trauma center, focusing on injury location, severity, co-morbidities, and surgical interventions to identify factors that may guide early interventions and improve survival rates. Material and Methods: This retrospective study reviewed patients with spinal fractures admitted to a Level 1 trauma center from 2017 to 2022, focusing on those with an Injury Severity Score (ISS) > 15. Data collected included demographics, injury mechanism, injury location, polytrauma (injury to two or more systems), and co-morbidities. Primary outcomes were in-hospital mortality (within 30 days), ITU length of stay, and surgical interventions. Injury classification followed the AOSpine Injury Classification System (types A-C) and Frankel Scores (Grade A-E). Mann-Whitney U-test for continuous variables and the chi-squared test for categorical data was used, with significance set at p < 0.05. Results: Among 1,549 suspected major trauma cases, 1,119 involved spinal injuries, with 396 patients having an ISS > 15 (major trauma). The mean age was 59 years (63% male, 37% female). Of these, 79% survived (n = 316), while 20% (n = 80) died within 30 days, resulting in an in-hospital mortality rate of 15.5%. Non-survivors had a mean age of 72.9 years compared to 54.8 years for survivors. Non-survivors had a significantly higher prevalence of co-morbidities (72.5% vs. 63% in survivors; p = 0.03) and polytrauma (92.5% vs. 87.8% in survivors; p = 0.04). Head injuries occurred in 76.3% of non-survivors compared to 41.3% of survivors. Falls were the most common cause of injury in both groups, with 50.7% in survivors and 73.8% in non-survivors. Road traffic accidents (RTA) were the second most common, occurring in 34.8% of survivors and 21.8% of non-survivors. In terms of injury types, non-survivors had more cervical spine fractures (57.5% vs. 34.1% in survivors) and AOSpine Type C fractures (15.5% vs. 11.4% in survivors). Frankel Scores indicated a higher proportion of Grade A injuries among non-survivors (20.0% vs. 5.1% in survivors). Surgical intervention rates were lower in non-survivors (11.3% vs. 23.9% in survivors; p < 0.05), with shorter ITU stays (6.5 days vs. 11.3 days; p < 0.01) possibly due to non-survivors dying in ITU. Among non-survivors, 95.8% required intensive care, compared to 35.4% in the survivor group. Conclusion: One-fifth of spinal trauma patients admitted to an urban Level 1 trauma center with ISS > 15 did not survive. Non-survivors were, on average, 18 years older and 10% more likely to have chronic co-morbidities compared to survivors. Falls from heights were the leading cause of mortality, particularly in the elderly, while non-survivors experienced significantly higher rates of multi-system injuries, including a 35% higher incidence of head injuries. Intensive care utilization was nearly triple that of survivors, suggesting a correlation between increased ITU demand and fatal outcomes. These findings highlight the necessity for earlier interventions of falls in elderly and optimisation of comorbid conditions to improve patient outcomes.

ID: 2931

A148: Comparative analysis of complications and patient-reported outcomes in operative versus nonoperative treatment of lumbopelvic dissociations

Arnaldo Martinez Rivera ¹ , Mark Lambrechts ¹ , Anna Miller ¹

¹ Washington University, St. Louis, United States

Sacral fractures present considerable challenges in treatment due to their complex anatomy, the interplay of biomechanical forces, and frequently poor bone quality. Both nonoperative and operative treatment options exist, particularly iliosacral screw fixation (ISF) and lumbopelvic fixation (LPF). However, a notable absence of standardized algorithms or definitive guidelines for the surgical management of these fractures persists. This study aims to fill this void by comparing nonoperative treatment to operative techniques - specifically ISF and LPF - in patients suffering from lumbopelvic dissociation, utilizing the AO spine sacral classification system. Study Objectives: The primary objective of this research was to evaluate complications, readmission rates, and health-related quality of life (HRQL) outcomes associated with each treatment modality. Materials and Methods: This retrospective study included adult patients diagnosed with sacral fractures linked to lumbopelvic dissociation (OTA/AO 61-A, B, C) who were treated at a Level I trauma center between 2011 and 2019. Patients exhibiting sacral pelvic dissociation (SPD) were identified using CT imaging. Key data collected included demographic information, injury severity, treatment modalities, and patient-reported outcomes. The classification of sacral fractures adhered to the AO system, and standardized radiographic measurements were utilized for assessment. The primary focus was to compare patient-reported outcomes (PROs) between surgical and nonsurgical treatments for sacral fractures with SPD. Secondary objectives included evaluating the impact of SPD on overall patient outcomes, such as total complications, reoperations, and the comparative effectiveness of surgical options. Statistical analyses were performed to assess HRQL, the Modified Frailty Index (mFI-5), complications, and length of hospital stay between surgical and nonsurgical cohorts. Results: A total of 64 patients were included in the study, comprising 29 males (46%) and 34 females (54%), all treated for unstable sacral fractures at a single academic Level I trauma center. The average age at injury was 60.23 years, with a mean injury severity score of 19.1. The predominant mechanism of injury was falling from a standing height, and the most common associated injury was a thoracic or lumbar spine fracture. Among the patients, 6 underwent LPF, while 40 received bilateral iliosacral screws; the remainder were treated nonoperatively. Among the operative cases, the C3 subtype was the most prevalent, comprising 63% of cases. The mFI-5 was significantly lower for C3 fractures treated operatively compared to those treated nonoperatively (p = 0.0029). Surgical intervention was successfully completed in 60% of patients, with no intraoperative complications reported. However, 8% of patients with ISF required hardware removal due to symptomatic issues, although no malpositioning was observed. In terms of HRQL, no statistically significant differences were noted between treatment groups. For the C0 subtype, the greatest observed difference related to pain interference, while for C3 fractures, differences were noted in depression scores; however, these differences did not reach statistical significance. Conclusion: The findings indicate that both treatment modalities yield similar outcomes and complication rates. Although ISF was associated with a higher incidence of symptomatic hardware removal, further research is necessary to identify optimal treatment strategies tailored to individual patient needs.

¹. ASTM international

ID: 247

A149: Non-operative management for patients with spinal ankylosing disorders presenting with extension type (AOSpine B3) fractures - Our experience with a cohort of 40 patients

Gal Barkay ¹ , Joel Fernandes ¹ , David Strong ¹ , Sean Suttor ¹ , Nathan Hartin ¹ , Randolph Gray ¹

¹ Royal North Shore Hospital, Sydney, Australia

Background: Non-operative treatment for patients with spinal ankylosing disorders presenting with extension type fractures (AOSpine B3) has been disregarded due to reports of poor outcomes including secondary fracture displacement and unacceptably high mortality rates. Recent studies have questioned the prevailing recommendation for surgical management, advocating for reconsideration of non-operative treatment in appropriate cases. We aim to further identify patient and radiographic factors favoring successful non-operative management. Methods: A retrospective analysis was conducted using data from Royal North Shore Hospital spine consult database. Patients with AOSpine B3 fractures treated non-operatively between 2021-2023 were included. Demographic, clinical, and radiographic data were collected and assessed, including outcome analysis of specific fracture patterns. Results: A total of 40 patients were treated non-operatively. 30 were deemed appropriate for non-operative management based on initial imaging assessment. Complications and 6-month mortality occurred in 13% of patients in this group. No patients failed non-operative management and good clinical and radiologic outcomes were observed in all patients on follow up. An additional 10 patients required surgery but were deemed medically unfit. Patients in this group were found to have a mortality rate of 80%. Conclusions: Non-operative management appears feasible for selected patients with DISH and AOSpine B3 fractures of an osseous or osseous-discal pattern, without posterior vertebral wall/annulus involvement and an anterior opening of up to 6 mm. These findings suggest non-operative treatment with close clinical and radiological follow up for specific patients is a viable treatment method in this patient group.

ID: 2161

A150: Percutaneous cross connectors - Utility, technique and outcomes of a minimally invasive method to maintain horizontal stability in pelvic fractures requiring spinopelvic instrumentation

David Gendelberg ¹ , Monty Khela ² , Ashraf El Naga ¹

¹ University of California, San Francisco, San Francisco, United States,

² Creighton University, Omaha, United States

Introduction: Pelvic ring injuries consist of a wide spectrum of injuries affecting the pelvic ring often requiring operative fixation. Unstable patterns include complete vertical posterior sacral fractures and iliosacral disruptions with diastasis in which the two hemipelvis are dissociated posteriorly. Maintaining compression is imperative for posterior pelvic injury healing or sacral fracture union. Ideal stabilization would provide both vertical stability and horizontal stability. While placement of spinopelvic instrumentation confers vertical shear stability, the hemipelvis could still displace by rotating around the axis of the pedicle screw. Traditionally, horizontal stabilization is achieved by placing a transiliac transacral screw (TTS). However, there are instances when TTS placement is not possible, most commonly in the dysmorphic, or transitional, pelvis or in the presence of other hardware. To prevent this rotational instability, it is necessary to place a horizontal cross connector between both rods, typically done with an open approach which is not ideal in this patient population who may have overlying soft tissue injuries. This case series describes the utility of and our technique for placing a minimally invasive, subfascial percutaneous cross connector to resist posterior pelvic ring diastasis of the pelvis in cases where a TTS is no feasible or if added fixation is needed. Materials and Methods: Percutaneous lumbopelvic fixation was performed. Bilateral L5 or S1 screws were placed through percutaneously using standard technique. A midline 4 cm incision was made distally at the lumbosacral junction which was use for placement of bilateral S2AI screws through fascial incisions medial to the PSIS. A 2 cm midline fascial incision was made to facilitate passing of a subfascial cross connector over the sacrum distal to the L5 spinous process. The cross connector is secured to each rod. Horizontal compression is applied across the rods, compressing across the fracture, and the cross connector is locked through the midline incision. Patient characteristics and radiographs were collected for patients undergoing this procedure between 2021-2024. Complication and outcomes were then recorded. Results: 10 patients were included in the study. Six had unilateral fractures and 4 had bilateral. Average age was 45.1. Two also had spinopelvic dissociation. There was an average of 86.5 cc of blood loss. Four patients were made weight bearing as tolerated post-operatively. Four patients had their weight bearing limited because of the presence of lower extremity injuries, two were non-weight bearing due to bone quality concerns. Mean follow up was 159 days. There was one complication, which was a broken cross connector discovered at the 6 month follow up. All other patients proceeded to full recovery. There were no re-operations for hardware complications. Conclusion: Placement of percutaneous cross connectors is a low morbidity, safe and effective way to treat pelvic fractures, particularly when a TTS screw is not feasible. It is minimally invasive avoiding the soft tissue complications associated with open lumbopelvic fixation and allows for immediate weightbearing in patients with complex pelvic ring injuries with challenging anatomy. Percutaneous cross connector placement is a useful technique when treating posterior pelvic ring injuries necessitating horizontal stabilization using spinopelvic fixation.

ID: 1054

A151: SCORE: multicenter randomized study for the treatment of osteoporotic odontoid fractures in the elderly - Rationale, study design and timeline

Maria Wostrack ¹ , Arthur Wagner ¹ , Victoria Kehl ² , Gisela Klatt ³ , Rita Stichling ⁴ , Barbara Ettinger ⁵ , Bernhard Meyer ¹

¹ Technical University Munich School of Medicine, Munich, Germany,

² Technical University Munich, Institute for AI and Informatics in Medicine, Munich, Germany,

³ Bundesselbsthilfeverband für Osteoporose e.V., Wendelstein, Germany,

⁴ Osteoporose Selbsthilfegruppen Dachverband e.V., Gotha, Germany,

⁵ Landesverband Bayern (LfO), Kitzingen, Germany

Introduction: Osteoporotic odontoid fractures are a common cervical spine injury in elderly people, increasing in relevance due to demographic aging and a higher fall risk. Currently, there is no clear scientific evidence on whether conservative treatment with a cervical collar or surgical stabilization is superior for these fractures. The aim of this nationwide multicenter randomized study is to gain reliable evidence-based insights focusing on the functional autonomy of geriatric patients. Material and Methods: This prospective multicenter randomized non-inferiority study includes patients aged 70 and above with acute odontoid fractures (Type II and III according to Anderson and d'Alonzo). Patients are randomized to either surgical stabilization with a screw-rod system or conservative treatment with a cervical collar for at least 12 weeks. The primary endpoint is the change in the Barthel Index between baseline and 12 weeks post-randomization. Secondary endpoints include quality of life (EQ-5D), duration of collar wear, hospital readmissions, Neck Disability Index (NDI), fracture healing (CT), crossover rates, and the visual analog scale (VAS). Additionally, endpoints assessing safety will be collected. Results: A total of 322 patients will be randomized in a 1:1 ratio. The sample size calculation accounts for a dropout rate of 15%, requiring the evaluation of data from at least 274 patients to achieve a statistical power of 90%. The study started in July 2024 and is planned to span 4.5 years, including the final publication of results. Sixteen spine centers across Germany have agreed to participate in recruitment. The study project is conducted in close collaboration with patient organizations such as the Federal Association of Osteoporosis (BfO), the Osteoporosis Self-Help Group Association (OSD), and the Bavarian Osteoporosis Self-Help State Association (LfO). Conclusion: The SCORE study will systematically evaluate for the first time the non-inferiority of surgical versus conservative treatment of osteoporotic odontoid fractures concerning functional status and quality of life in geriatric patients. The results will help close existing knowledge gaps and improve clinical practice through evidence-based recommendations. Special emphasis is placed on increasing the autonomy and quality of life of affected patients, which is underscored by the involvement of patient organizations and a focus on patient-relevant endpoints.

ID: 2591

A152: Comparison of safety and efficacy of percutaneous vesselplasty and vertebroplasty in chronic, non-healing osteoporotic thoracolumbar vertebral fractures: a prospective, comparative study

Akhil Monga ¹ , Nishank Mehta ¹ , Bhavuk Garg ¹ , Madhusudan Ks ¹ , Ankur Goyal ¹ , Deep Narayan Srivastava ¹

¹ All India Institute of Medical Sciences, New Delhi, India

Introduction: Osteoporotic vertebral compression fractures (OVCF), not responsive to conservative management are often treated with vertebral augmentation procedures (VAP) like vertebroplasty and kyphoplasty. Both these procedures, however, carry a risk of cement leakage causing pulmonary embolism or spinal cord compression. Vesselplasty is a new modification of percutaneous vertebroplasty (PVP) which involves the use of a polyethylene terephthalate (PET) balloon container which serves the dual purposes of creating space within the vertebral body as well as containing the injected cement, theoretically eliminating the risk of cement leakage. We aimed to compare the safety and efficacy of vesselplasty and PVP in patients with chronic, non-healing, symptomatic cases of thoracolumbar OVCF who did not respond to conservative management. Material and Methods: Forty-five consecutive patients with chronic thoracolumbar OVCF (duration ≥ 8 weeks) causing severe pain (Visual analogue scale; VAS ≥ 7) and disability attributable to OVCF who were not responding to conservative treatment, were included in the study. Twenty-eight patients underwent vertebroplasty (Group A) and 16 patients underwent vesselplasty (Group B) using a standardized technique. The two groups were compared for difference in the post-procedure physical functionality (SF-36 physical function) and post-procedure VAS scores at one week and three months post procedure. Comparative analysis was also done for reduction in analgesic requirement, volume of cement injected, change in the vertebral body height and rate of complications, including cement leakage. Results: A total of 45 patients (31 females; 14 males) with a mean age of 69 years (range: 51 - 83 years) underwent 49 VAPs. Twenty-eight patients underwent vertebroplasty involving 33 vertebrae (Group A) and 17 patients underwent vesselplasty in 17 vertebrae (Group B). The distribution of the fractures by location was as follows: D11 = 9, D12 = 15, L1 = 17, L2 = 8. The two groups did not differ with respect to baseline demographic or clinical characteristics. The mean VAS score at one week (Group A: 3.13, 95% CI – 2.65/3.61 v/s Group B: 3.07, 95% CI – 2.31/3.32) and 3 months post-procedure (Group A: 2.81, 95% CI – 2.31/3.32 v/s Group B: 2.72, 95% CI – 2.36/3.06) was comparable between the two groups. Patients in Group B (vesselplasty) however had a significantly better post-procedure SF-36 physical functionality score at one week and 3 months follow-up. The quantity of cement injected (Group A: 3.84 ml v/s Group B: 4.68 ml), mean increase in anterior vertebral height (Group A: 0.635 mm v/s Group B: 2.472 mm, mean increase in central vertebral height (Group A: 0.63mm v/s Group B: 1.96mm) also differed significantly between the two groups. Cement leakage, though asymptomatic, was seen in 14 patients (50%) in Group A whereas no patient in Group B had a cement leak. Conclusion: Vesselplasty significantly reduces the incidence of cement leakage in thoracolumbar OVCF with similar or better relief in pain, improvement in disability scores and vertebral body height. It can be a safer alternative to PVP especially in patients with posterior cortical breach.

ID: 484

A153: Health-related quality of life and return to work after traumatic spinal fractures without spinal cord injury after one year: a prospective, longitudinal follow-up study

Mathijs Suijkerbuijk ¹ , Fijneman Liv ¹ , Egmond, van Pim ¹ , Joosen Margot ² , Jongh Mariska ^2,3 , Ruth Geuze ¹

¹ ETZ, Orthopedics, Tilburg, Netherlands,

² Tilburg University, Trans Scientific Center for Care and Well-being, Tilburg, Netherlands,

³ ETZ, Network Emergency Care Brabant, Tilburg, Netherlands

Introduction: The incidence of traumatic spinal fractures without spinal cord injury (SCI) is increasing and is associated with high socioeconomic and medical costs. However, the impact on patients’ life remains unclear. Therefore, this study aims to describe the health-related quality of life (HRQoL) and return to work (RTW) following traumatic spinal fractures without SCI within the first year following trauma. Materials and Methods: Patients were included in a prospective, longitudinal follow-up cohort study between 2015 and 2016 in which the HRQoL and RTW were assessed during a 12-months follow-up period. Included patients met the following criteria: (1) age ≥ 18 years, (2) traumatic spinal fracture without signs of a SCI, (3) type A or B fracture of the cervical, thoracic or lumbar spine. All included patients underwent conventional imaging and/or additional CT scan as well as a complete neurologic exam to confirm diagnosis. The EuroQoL-5D-3L (EQ-5D-3L) was used to assess the HRQoL. RTW as determined from patient-reported questionnaires (1 = yes, 0 = no) and defined as the first time a patient started working after hospital admission. Data were collected by self-reported questionnaires at 1 week and 12 months after injury. A paired t-test was used to test for significance (p < 0.05). Results: A total of 138 patients with traumatic spinal fractures without SCI were identified. The fractures included cervical (n = 56), thoracic (n = 43) and lumbar fractures (n = 39), including 23 occipitocervical fractures, 79 type A fractures, 29 type B fractures, and 7 (unilateral) facet fractures. One year after trauma, 45% of patients experience limitations with mobility or daily activities, 64% report pain, and 26% experience psychological stress. No differences in EQ-5D-3L scores were found when comparing type A and type B fractures. Of the 69 patients who were employed before trauma, 35 (51%) were able to return to work within 12 months following trauma. Conclusion: The results of this study demonstrate that traumatic spinal fractures without SCI have a significant impact on patients' lives for at least 12 months after the injury. The majority of patients report persisting pain which possibly results in limitations with mobility or psychological distress, limiting their quality of life. Both type A and type B fractures appear to affect the HRQoL equally. In addition, half of the patients was unable to RTW within the first year after spinal fractures, which should be taken into account when counseling these patients. Future research should focus on identifying the factors that influence recovery after traumatic spinal fractures to accelerate patient recovery, improve their quality of life and mitigate the socio-economic consequences.

OP18: Novel Technologies and Innovations 3

ID: 868

A154: Utility and reliability of GPT-4o in developing treatment recommendations for complex spine pathologies

Ara Khoylyan ¹ , Jefferson Waters ¹ , Jason Salvato 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: There is growing evidence for the utility of large language models (LLM), such as ChatGPT, in optimizing the delivery of healthcare. Spine disease, often requiring complex surgical intervention, affects a large portion of the U.S. population. There is limited data available for the potential utility of ChatGPT in accurately identifying surgical or non-surgical spine treatment options. The purpose of this study is to explore the utility and reliability of GPT-4o in this capacity. We hypothesize that this software will have significant agreement with established treatment protocols for a wide spectrum of spinal pathologies. Material and Methods: 38 clinical vignettes involving traumatic, degenerative, or congenital spine pathologies were sourced from the textbook “Challenging Cases in Spine Surgery” by Abdulhak et al. Each case included history of present illness, physical examination findings, radiographic findings, and established treatments. Treatments were divided into respective categories. Standardized prompts were created presenting each clinical vignette to GPT-4o and querying for elected treatment category(s), which was then compared to the textbook protocol. The software was queried with three identical prompts in individual strings for each case to evaluate for interquery agreement. Majority response was determined from these three queries and established as the GPT-4o response. Majority response was then assessed for complete agreement, partial agreement, or disagreement with the textbook for elected treatment(s). GPT-4o responses were also extracted for diagnosis, recommended treatment details, and rationale, and subsequently scored for accuracy in comparison to the textbook by a board-certified spine surgeon. Factors for evaluation were alignment of elected surgical technique, surgical approach, spinal level of treatment, and treatment goal. A composite score of one corresponds with no concordance, two with partial concordance, and three with complete concordance in all four aspects. Descriptive and inferential statistics were performed. Results: There was treatment concordance between GPT-4o responses and the textbook in 84% (32/38) of cases. GPT-4o agreed with the textbook that a specific treatment was indicated 80% (49/61) of the time and not indicated 93% (226/243) of the time (χ2 = 154.3, p < 0.001). Sensitivity was highest for correctly predicting the necessity of decompression surgery (Sn 95%, Sp 84%, n = 18) and lowest for posterior fusion surgery (Sn 64%, Sp 88%, n = 9). The software had 83% interquery agreement between all treatment types. Mean accuracy score of GPT-4o responses was 2.26 (SD 0.64). Conclusion: GPT-4o shows promising utility in correctly identifying and recommending generalized treatments for complex spinal traumatic, degenerative, and congenital pathologies. GPT-4o has also demonstrated significant interquery reliability and reproducibility when electing spine treatments. While generally correct, inaccuracies and variations are observed in the specifics of GPT-proposed surgical treatment against author recommendations and may reflect the overall complexity of spine surgery and wide array of treatment options based on surgeon experience, training, and preferences. Further research is needed to elucidate GPT-4o’s clinical applicability, particularly with reference to established treatment guidelines.

ID: 2905

A155: Development and validation of an extreme gradient boosting model to predict reoperation following surgical site infection: an analysis of 96,216 patients using the ACS NSQIP database

Mert Dagli ¹ , Hasan Ahmad ¹ , Daksh Chauhan ¹ , Ryan Turlip ¹ , Kevin Bryan ¹ , Jaskeerat Gujral 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: The volume of lumbar spinal surgeries performed in the United States has been rising steadily, and surgical site infections (SSIs) represent a significant postoperative complication. SSIs contribute to patient morbidity and impose a considerable financial burden on healthcare systems due to extended hospital stays, emergency department visits, readmissions, and increased outpatient follow-ups. This study aimed to develop, and internally and externally validate, an artificial intelligence (AI) model using extreme gradient boosting (XGBoost) to predict reoperation following SSIs in lumbar spine surgery. 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 used the American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) database to identify patients who underwent lumbar spine surgery based on surgical procedure codes. Given the rarity of SSIs, the analysis included three types: superficial SSI, deep incisional SSI, and organ/space SSI. Predictor variables used in the AI model included SSI types, wound infection, preoperative albumin <3.5, preoperative hematocrit, preoperative white blood cell count, preoperative serum alkaline phosphatase, ASA classification, functional status, diabetes status, age, and race. After initial analysis, weighted extreme gradient boosting (XGBoost) was identified as the optimal machine learning method. A comprehensive grid search was conducted, and model performance was assessed through internal and external validation. An institutional database was used for external validation. Performance metrics included accuracy, recall (sensitivity), area-under-curve receiver-operating-characteristic (AUC-ROC), area-under-precision-recall-curve, F1-score, and positive predictive value (PPV). Bootstrapping was used to calculate 95% confidence intervals (CIs), and feature importance analysis was performed. Results: The study cohort included 96,216 patients who underwent lumbar spinal surgery. The weighted XGBoost model demonstrated an exceptional accuracy of 0.9939, a sensitivity of 0.8000, and an AUC-ROC of 0.9974. Feature analysis revealed that the most important predictors of reoperation following SSIs included wound infection types, preoperative albumin levels, and ASA classification. Conclusion: This study demonstrated the accuracy and reliability of an AI-based extreme gradient boosting model for predicting reoperation due to SSIs following lumbar spine surgery. The implementation of AI models for SSI prediction enables improved risk stratification and optimized resource allocation. Future research will focus on external validation of the model to strengthen its predictive power, as well as additional training to improve the sensitivity by analyzing false positive and false negative cases.

ID: 2468

A156: Research on cutting state recognition of spinal laminectomy robot

Zhuofu Li ¹ , Weishi Li ¹

¹ Peking University Third Hospital, Beijing, China

Introduction: The main function of the spinal robot in clinical application focuses on pedicle screw placement. Laminectomy, which is just as important as pedicle screw placement, lacks a mature robotic assistance system. For this reason, the research group developed a robot system that can identify and cut the laminae autonomously. How to ensure the safety of autonomous cutting is one of the research difficulties. The purpose of this study is to explore the robot autonomous lamina cutting status recognition method and explore its feasibility. Material and Methods: Taking pig vertebrae as the research object, the force and displacement information of the whole process from contact to penetration of the laminectomy was collected, and the two states of non-penetration and penetration were marked manually. Long Short Term Memory Fully Convolutional Neural Networks (LSTM-FCN) and Multilayer Perceptron (MLP) was used as a classification algorithm to classify the two states of the robot cutting not penetrated and penetrated, and the classification accuracy was calculated. The two methods were combined to form an overall status recognition scheme, and verification experiments were carried out on the laminae of 10 pig vertebrae to record the total number of operations, whether there was penetration each time and the remaining thickness of the unpenetrated laminae. Results: In the training of LSTM-FCN algorithm, 25,599 data pairs were finally collected, of which 15294 were pre-penetration and 10305 were penetration. It is divided into training set, verification set and test set according to the ratio of 3:1:1, and the classification accuracy is 95.89%. A total of 26,453 data sets were acquired by MLP algorithm training, including 16145 unpenetrated data sets and 10308 penetrated data sets. According to the ratio of 3:1:1, it was divided into training set, verification set and test set, and the classification accuracy was 95.67%. A total of 139 cuts were performed under the overall condition recognition scheme, of which only one was penetrated, the non-penetrated rate was 99.28%, and the average remaining thickness of the lamina was 1.04 ± 0.5 mm. Conclusion: The results of the study verify the accuracy of the robot system to identify the cutting state, which lays a foundation for the subsequent clinical application.

ID: 2470

A157: Artificial intelligence enabled spinal laminectomy robot system

Weishi Li ¹

¹ Peking University Third Hospital, Beijing, China

Introduction: The clinical application of spinal surgical robots mainly focuses on auxiliary pedicle screw placement, and there is a lack of auxiliary laminectomy robot system. To this end, the research group has developed an autonomous spinal laminectomy robot in the early stage. In earlier studies, the robot has been able to remove a single lamina. However, the actual decompression of laminectomy often requires spanning multiple segments. In order to achieve this requirement, it is necessary to achieve intraoperative posture registration of multi-articular vertebrae and safe excision of complex bone structures in the overlapping areas of upper and lower articular processes. In this study, artificial intelligence technology was introduced to realize intraoperative multi-level vertebral pose registration and automatic surgical planning, as well as chip status recognition under complex bone levels. The effect of laminectomy was evaluated by cadaver experiment. Material and Methods: A total of 17 vertebrae from 3 cadaveric specimens were included in the study. A multi-vertebral laminectomy was performed on the thoracic and lumbar vertebrae. After obtaining CT data, the robot system planned the laminectomy path according to the AI algorithm, including the scope and depth of the laminectomy (the lower part of the upper laminae, the entire part of the middle laminae and the upper part of the lower laminae), as well as the bone hierarchy of the overlapping part of the articular process. Multiple vertebral poses were registered and planned resection paths calibrated during the procedure, followed by automatic decompression by the robot. Postoperative CT scan was performed to quantitatively analyze the deviation of each cutting plane from the preoperative plan, evaluate the cutting effect, and record the time of laminectomy. Results: Three two-level laminectomies (T9-T11) were performed in the thoracic vertebrae, two two-level laminectomies (L3-5) and one single-level laminectomy (L4-5) in the lumbar vertebrae. The average time for unilateral longitudinal cutting was 983.00 ± 285.72 seconds, and the average time for lateral cutting was 266.50 ± 91.28 seconds. In terms of accuracy assessment, 77 (84%) were rated excellent (Grade A), 15 (16%) were rated good (grade B), and none were rated poor (grade C). The laminae were easily removed, and the structure of the ligamentum flavum between the laminae was intact. There was no damage to the dural sac. Conclusion: The results of the study verified that the improved autonomous laminectomy robot system can accurately perform multi-segment thoracolumbar laminectomy, laying a foundation for subsequent clinical application.

ID: 2324

A158: 3D printed dural tear repair training sumulation model

Daniel Lobos ¹ , Javier Castro ¹ , Jorge Cuéllar ¹ , Byron Delgado Ochoa ¹ , Hugo Demandes ¹ , Mauricio Campos ¹

¹ Pontificia Universidad Catolica de Chile, Traumatologia, Santiago, Chile

Introduction: Dural tear repair in the lumbar spine is an essential and complex technique, but it is rarely trained during residency and fellowship periods. Simulation has made it possible to train different surgical procedures with validated models. Our group designed a dural repair training model using a 3D printer. The objective of this work is to validate the training model and analyze the learning curve in trauma residents trained with the dural repair model. Material and Methods: Experimental design study. In the first phase, four expert spine surgeons were measured and compared with four inexperienced spine surgeons (less than three procedures) in the model. In the second phase, eight residents in 4 sessions separated by one week were trained on the 3D printed model. In both phases and each training session, the dural defect repair technique was evaluated through the OSATS performance scale, performance time, and distance traveled by both hands, using the ICSAD system. The scores obtained by the experts and inexperienced at baseline and the pre-and post-training results were compared. Results are reported in medians and range. The Mann-Whitney, Wilcoxon, and Friedman tests were used. Statistical significance p < 0.05. Results: When performing the exercise in the model, expert surgeons had a significantly higher OSATS score than inexperienced surgeons (21 (19-23) vs. 17 (16-17) (p = 0.02), shorter execution time (271 vs. 341 seconds (p = 0.04), and no differences in the distance traveled by both hands (28.5 meters vs. 26.2 (p = 0.8)). At the end of the training, if the first session is compared to the last session, the trained residents improved significantly for OSATS 13 (8-15) vs. 18 (17-20) (p < 0.01) and execution time 363 vs. 278 seconds (p = 0.02). The distance traveled with the dominant hand, 14 vs. 31.5 meters, and non-dominant, 16 vs. 29.4 meters, did not improve significantly. If compared with the experts, at the end of the training, the residents reach the level of the experts in execution time, 278-second residents vs. 271-second experts (p = 0.9), but not in OSATS 18 (17-20) vs. 21 (19-23) p = 0.02. There are also no differences in the distance traveled with both hands. Conclusion: The designed model allows us to differentiate novices from experts. After four training sessions on the model, the residents improved in OSATS and execution time but only reached the level of the experts in execution time. More training sessions or moving to more complex models may be required.

ID: 127

A159: 3D-printed laminae for kyphosis in ankylosing spondylitis in pedicle subtraction osteotomy

Yilin Lu ^1,2,3 , Gao Si ^1,2,3 , Mingxiao Bai ⁴ , Yongqiang Wang ^1,2,3 , Weishi Li ^1,2,3 , Miao Yu ^1,2,3 , Yu Wang ⁵

¹ 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,

⁴ Rizhao Hospital of Traditional Chinese Medicine, Rizhao, China,

⁵ Peking University First Hospital, Beijing, China

Background: Ankylosing spondylitis (AS) often presents with spinal kyphosis, and pedicle subtraction osteotomy (PSO) is a common surgical technique for correcting AS-related kyphosis. However, after PSO, the posterior column lacks rigid bone support, potentially leading to intervertebral disc mobility and loss of correction. In this study, we propose a novel approach using 3D-printed laminae to enhance posterior column stability and reduce deformity loss. Methods: 48 patients were included, with 16 receiving 3D-printed laminae implants. We collected preoperative and postoperative radiographic parameters, perioperative data, and patient-reported clinical scores. Statistical analysis involved independent sample t-tests or randomization tests for continuous variables and chi-square tests for categorical variables. Results: In the implanted group, kyphosis was corrected from 75.88° preoperatively to 27.06° postoperatively, and in the un-implanted group, from 70.98° to 28.42°. At the last follow-up, the ΔGK (global kyphosis correction) was 1.76° in the implanted group and 2.50° in the un-implanted group. PJA was 9.77° in the implanted group and 15.45° in the un-implanted group, showing significant differences. Two patients in the un-implanted group experienced sagittal reconstruction failure. Health-related quality of life (HRQoL) scores improved in the implanted group, with back pain scores of 2.63 and Oswestry Disability Index (ODI) scores of 13.50. Conclusion: Our study introduces a novel 3D-printed laminae technique for AS-related kyphosis, aiding in maintaining sagittal balance. Patients reported improved subjective outcomes, including reduced pain and better HRQoL. The potential of this paper is that we have for the first time proposed and produced a 3D-printed lamina, which has achieved satisfactory clinical efficacy and helps to optimize the prognosis of PSO surgery in AS patients with kyphosis.

Keywords: Ankylosing spondylitis; Kyphosis; Pedicle subtraction osteotomy; 3D-printed.

ID: 1186

A160: Early experience with prone single position corpectomy: feasibility, radiographic outcomes and complications

Ryan Le ¹ , Nischal Acharya ¹ , Haley Nadone ¹ , Hao-Hua Wu ¹ , Sohaib Hashmi ¹

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

Introduction: The use of lumbar corpectomy and posterior stabilization has been well described in various pathologies. Historically, this was performed using anterior approach; however this has since been associated with numerous postoperative complications. Given these, there has been a trend toward various alternative approaches. The lateral decubitus corpectomy with subsequent or staged posterior stabilization is a known technique. We describe our experience with the single position prone retropleural and transpsoas corpectomy which allows for simultaneous anterior and posterior column access in a single stage. Currently, there is limited literature for single position lumbar corpectomy in adult patients. We present a cohort of patients who underwent prone retropleural or transpsoas corpectomy and posterior decompression and stabilization for trauma, deformity, infection, and tumor. Material and Methods: We conducted a retrospective review of 9 consecutive adult patients who underwent prone transpsoas corpectomy at University of California, Irvine from January - December 2023. All patients underwent a single staged, single position prone lateral transpsoas lumbar corpectomy with posterior instrumentation. Clinical data collected included: demographics, corpectomy level, instrumented levels, intraoperative complications, operative duration, blood loss, and postoperative outcomes. Perioperative complications including infection, neurological deficit, hardware failure, screw pullout, and need for reoperation were also reviewed. Results: Of the 9 patients, 6 received single level corpectomy, and 3 received 2-level corpectomy. Average age was 53.8 years (range: 29-69), with 3 female and 6 male patients. There were 4 pathologic fractures, 3 Lumbar burst fractures, and 2 vertebral osteomyelitis with collapse. Of the 9 patients, 4 had undergone and failed previous surgery for their pathologies. Levels of corpectomy included L1 (4), L2 (1), L4 (1), L1-2 (1) and L3-4 (1). Total posterior instrumentation was on average 1.89 levels above and below the level(s) of corpectomy, with cement augmentation performed in 5 patients. The average preoperative sagittal alignment was 23.5 degrees of kyphosis, while the average postoperative sagittal alignment was 12.3 degrees of lumbar lordosis with an average change of 35.5 degrees in sagittal alignment. No iatrogenic dural tears were noted. Following an average length of stay of 12.7 days (5-21), 6 patients were discharged home and 3 to an acute rehabilitation unit. One patient required reoperation for posterior instrumentation revision in the setting of chronic osteomyelitis infection. We otherwise did not note any new neurologic deficit or lower extremity weakness, hardware failure, infection, pseudoarthrosis or adjacent segment disease in the remaining 8 patients. Conclusion: Prone transpsoas single position corpectomy is a safe and reliable technique for simultaneous anterior and posterior decompression, instrumentation, and fusion. Our series demonstrated 35.5 degrees of sagittal correction, and restoration of alignment in a safe and efficacious manner.

ID: 1469

A161: AI-powered 3D reconstructions from stereo-radiographs: is 3D ready for primetime

Justin Dufresne ¹ , Rachelle Imbeault ¹ , Marjolaine Roy-Beaudry ¹ , Cresson Thierry ² , Stefan Parent ¹

¹CHU Sainte-Justine, Montreal, Canada, ²Ecole de Technologie Supérieure, Montréal, Canada

Introduction: 3D reconstructions of the spine have been used for over 30 years mainly in a research environment. The main limitation to their clinical use has been access to rapid and accurate 3D reconstructions. This study assesses the accuracy and reliability of a newly developed AI-powered software for generating 3D spine reconstructions from 2D X-ray images, focusing on idiopathic scoliosis. Our aim is that the newly developed AI-powered software can generate accurate 3D spine reconstructions with significantly improved efficiency compared to the previous generation semi-automatic software. Material and Methods: This retrospective cohort data initially focuses on validating the accuracy of the AI-powered software by comparing 100 automatic reconstructions with those performed using a semi-automatic tool, which were validated by a third party (surgeon/3D reconstructions expert). Clinical parameters, including Cobb angle, thoracic kyphosis, lumbar lordosis, pelvic tilt, and plane of maximal deformity, are assessed. Following validation, the study shifts to creating a robust database by generating 1000 reconstructions using the validated automatic software. Results: Mean absolute differences (MAD) were observed for the Cobb angle (4.1° ± 4.4), thoracic kyphosis (4.9° ± 3.9), lumbar lordosis L1-L5 (4.8° ± 4.3), lumbar lordosis L1-S1 (3.1° ± 2.2), pelvic tilt (1.1° ± 1.2) and the plane of maximal deformity (6.2° ± 6.7). The ICC for each variable respectively was 0.84, 0.87, 0.82, 0.94, 0.95, and 0.84. Strong positive correlation coefficients were found: 0.76 for the Cobb angle, 0.89 for thoracic kyphosis, 0.76 for lumbar lordosis L1-L5, 0.89 for lumbar lordosis L1-S1, 0.92 for pelvic tilt and 0.72 for the maximum plane angle. Notably, the AI-powered software reduced the time required for a single 3D reconstruction to 2.21 minutes, demonstrating significant efficiency gains compared to the semi-automatic software, which took on average 74 minutes. Conclusion: This study confirms the precision of 3D spinal reconstructions generated by the AI software for database creation, demonstrating the successful automation of large-scale datasets. However, individual variability remains, and clinicians should exercise caution when using these methods interchangeably.

ID: 728

A162: Evaluation the effectiveness of AI-based pedicle screw trajectory planning in lumbar degenerative disease patients with osteopenia or osteoporosis: a prospective study

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

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

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

Introduction: Lumbar degenerative diseases (LDD), including lumbar spondylolisthesis, spinal stenosis, and disc herniation, are prevalent conditions that often require spinal surgery. Surgical interventions are recommended when conservative treatments are ineffective. During these surgeries, pedicle screws are typically used to ensure stability, which is crucial for achieving successful fusion. However, one of the major challenges associated with this technique is the potential loosening of pedicle screws, particularly in patients with osteopenia and osteoporosis. Artificial intelligence (AI) has emerged as a promising tool in various medical fields, particularly in spine surgery. AI application in spinal surgery is in its early stages, and clinical trials are needed to evaluate its efficacy and safety. The purpose of this study was to evaluate the effectiveness of AI-based pedicle screw trajectory planning in patients with LDD accompanied by osteopenia or osteoporosis. Material and Methods: A prospective non-randomized study was conducted between October 2022 and February 2023, including patients with LDD accompanied by osteopenia or osteoporosis and who underwent open posterior lumbar decompression and fusion surgery. Participants were prospectively enrolled and subsequently allocated into either the AI group or the free-hand (FH) group based on their preference. The AI group utilized AI software for preoperative screw trajectory planning, followed by the placement of pedicle screws using a spinal robotic system that adhered to the planned trajectory. Clinical and imaging outcomes were compared between the two groups. Results: This study included 90 patients, with 53 classified as osteoporosis and 37 as osteopenia. Both osteoporosis and osteopenia patients in the AI group demonstrated a higher pullout force (POF) and a greater rate of perfect screw position (grade A) compared to the FH group (p<0.05). Among those with osteoporosis, the AI group demonstrated a lower incidence of screw loosening, shorter time to bone graft fusion, and lower VAS for low back pain and ODI at final follow-up compared to the FH group (p<0.05). Conclusion: AI-assisted pedicle screw trajectory planning can reduce screw loosening rates and improve clinical outcomes in patients with LDD accompanied by osteoporosis.

Keywords: artificial intelligence; lumbar degenerative disease; osteoporosis; osteopenia; pedicle screw

OP19: Spine Infections

ID: 276

A163: Management of severe spinal infections: the 2SICK Study by the EANS spine section

Andreas Kramer ¹ , Santhosh G. Thavarajasingam ¹ , Jonathan Neuhoff ² , Felipa Lange ¹ , Hariharan Subbiah Ponniah ³ , Andreas Demetriades ⁴ , Benjamin Davies ⁵ , Ehab Shiban ⁶ , Florian Ringel ¹ , Eans 2Sick Studygroup ⁷

¹ University Medical Center Mainz, Department of Neurosurgery, Mainz, Germany,

² Berufsgenossenschaftliche Unfallklinik Frankfurt am Main, Center for Spinal Surgery and Neurotraumatology, Frankfurt am Main, Germany,

³ Imperial College London, Imperial Brain & Spine Initiative, London, United Kingdom,

⁴ Royal Infirmary Edinburgh, Department of Neurosurgery, Edinburgh, United Kingdom,

⁵ Addenbroke's Hospital, Cambridge University Hospital NHS Healthcare Trust, Cambridge, Department of Academic Neurosurgery, Cambridge, United Kingdom,

⁶ Universitätsklinikum Augsburg, Department of Neurosurgery, Augsburg, Germany,

⁷ European Association of Neurosurgical Societies (EANS), Brussels, Belgium

Introduction: Spondylodiscitis management presents significant clinical challenges, particularly in critically ill patients, where the risks and benefits of surgical intervention must be carefully balanced. The optimal timing of surgery in this context remains a subject of debate. This study aims to evaluate the effectiveness of early surgery versus delayed surgery or conservative management in critically ill patients with de novo pyogenic spondylodiscitis. Material and Methods: This international, multicenter retrospective cohort study analyzed patients from 24 centers, predominantly in Europe, treated between 2015 and 2022. The study focused on patients severely affected by pyogenic spondylodiscitis, characterized by an initial CRP level > 200 mg/l or the presence of two out of four Systemic Inflammatory Response Syndrome criteria upon admission. Patients were divided into early surgery (within 3 days of admission), delayed surgery (after 3 days of admission), and conservative therapy groups. The primary outcome was 30-day mortality. Secondary outcomes included length of ICU stay, length of hospital stay, and relapse rates. Results: Delayed surgery was associated with significantly lower 30-day mortality (4.05%) compared to early surgery (27.85%) and conservative therapy (27.78%) (p < 0.001). Delayed surgery also resulted in shorter hospital stays (42.76 days) compared to conservative therapy (55.53 days) and early surgery (26.33 days) (p < 0.001), and shorter ICU stays (4.52 days) compared to conservative therapy (16.48 days) and early surgery (7.92 days) (p < 0.001). The optimal window for surgery, minimizing mortality, was identified as ten to fourteen days post-admission (p = 0.02). Risk factors for increased mortality included multiple organ failure (p < 0.05), vertebral body destruction, and cervical infection location, whereas the presence of an epidural abscess was associated with reduced mortality (p < 0.05). Conclusion: Delayed surgery, optimally between 10 to 14 days post-admission, was associated with lower mortality in critically ill spondylodiscitis patients. These findings highlight the potential benefits of considering surgical timing to improve patient outcomes.

ID: 922

A164: AO Spine Primary Spine Infection Classification System: a unifying approach to standardize patient care

Brian Karamian ¹ , Rajkishen Narayanan ² , Jonathan Dalton ² , Richard Bransford ³ , Marcel F. Dvorak ⁴ , Harvinder Singh Chhabra ⁵ , Andrei Joaquim ⁶ , Mohammad El-Sharkawi ⁷ , Lorin Benneker ⁸ , Klaus Schnake ^9,10 , Cumhur Oner ¹¹ , Jose Canseco ² , Chris Kepler ² , Alex Vaccaro ² , Gregory Schroeder ²

¹ University of Utah, Orthopaedic Surgery, Salt Lake City, United States,

² Rothman Orthopaedic Institute, Philadelphia, United States,

³ University of Washington, Orthopaedic Surgery, Harborview Medical Center, Seattle, United States,

⁴ Vancouver General Hospital, Vancouver, Canada,

⁵ Sri Balaji Action Medical Institute, New Delhi, India,

⁶ University of Campinas, Campinas, Brazil,

⁷ Assiut University Medical School, Assiut, Egypt,

⁸ University of Bern, Sonnenhof Spital Bern, Bern, Switzerland,

⁹ Malteser Waldkrankenhaus St. Marien, Center for Spinal and Scoliosis Surgery, Erlangen, Germany,

¹⁰ Paracelsus Private Medical University, Department of Orthopedics and Traumatology, Nuremberg, Germany,

¹¹ University of Utrecht, Orthopaedic Surgery, Utrecht, Netherlands

Introduction: Primary spine infections (PSIs) have high morbidity and mortality. Currently there is no universal PSI classification system, which limits diagnosis, prognosis, and management standardization. This study aims to address that gap in the literature by utilizing the Delphi method to collate expert opinion on the most critical aspects of PSI treatment. The overarching goal is to derive a comprehensive classification system to standardize management for this vulnerable patient population. Materials and Methods: The Delphi method was used by the AO Spine Knowledge Forum (KF) Trauma & Infection to reach consensus and consisted of three rounds: two surveys followed by an in-person discussion. Each survey was open for three weeks followed by a three-month interval to compile responses and prepare for the next round. All participants were blinded to the identity of individual responses and only anonymized, aggregated responses were shared with the group. The first survey was created by identifying overarching categories and sub-categories from existing spine literature and from virtual brainstorming sessions with the AO Spine KF Trauma & Infection experts. Respondents were asked to rank the importance of each category on a scale of 1-3 (not important), 4-6 (important), and 7-10 (extremely important). In the first survey, participants could suggest new categories with justifications, which were reviewed for the second round. In the second round, participants reviewed their previous ratings and the group’s aggregated score. Stability of responses was assessed and if deemed unstable, subsequent rounds were required until consensus. Consensus was defined as ≥70% agreement, which determined inclusion/exclusion of categories. Final categories were discussed at the in-person meeting for further deliberation. Results: Of the 28 members, 24 participated in the first survey to rate 6 overarching categories and 39 subcategories. Two additional subcategories were suggested and added into round two. In the second survey, 23 of 24 experts responded. Ratings were similar to the first round; thus categories were deemed stable. One sub-category deemed not important (1-3) was excluded. 21 sub-categories and four overarching categories were deemed extremely important (7-10) and were thus included. The remaining 19 sub-categories and two overarching categories were deemed important (4-6) and were thus discussed in round three. The final classification system consists of four overarching categories and their related subcategories. 1) Location is subcategorized into A-lumbar, B-thoracic, C-cervical. 2) Morphology is subcategorized into 0-extra-spinal, 1-osteomyelitis and/or discitis without canal involvement, 2-canal involvement without neural compression, 3-canal involvement with neural compression. Additionally, the “+” modifier can be added to morphologic subcategories 1-3 to indicate bony destruction. 3) Neurologic status is subcategorized into N0-intact, N1-transient deficit, N2-radicular symptoms, N3-incomplete/cauda equina, N4-complete, and NX-unknown. 4) Modifiers is subcategorized into M1-inability to mobilize due to pain intractable pain with possible instability, M2-medical complications affect treatment, and M3- suspicion of atypical infections. Conclusion: This study proposes a universal PSI classification system derived from the AO Spine KF Trauma and Infection. This system encompasses location, infection morphology, neurologic findings, and modifiers. Future work includes extensive validation of this system in order to confirm broad generalizability.

ID: 1606

A165: [18F]FDG PET/CT imaging is associated with lower in-hospital mortality in patients with pyogenic spondylodiscitis - A registry based analysis of 29,362 cases

Siegmund Lang ¹ , Nike Walter ¹ , Stefanie Heidemanns ² , Constantin Lapa ³ , Melanie Schindler ^1,4,5 , Jonas Krueckel ¹ , Nils-Ole Schmidt ⁶ , Dirk Hellwig ² , Volker Alt ¹ , Markus Rupp ¹

¹ University Hospital Regensburg, Trauma Surgery, Regensburg, Germany,

² University Hospital Regensburg, Nuclear Medicine, Regensburg, Germany,

³ University Augsburg, Nuclear Medicine, Augsburg, Germany,

⁴ Karl Landsteiner University of Health Sciences, Department for Orthopedics and Traumatology, Krems, Austria,

⁵ University Hospital Krems, Division of Orthopaedics and Traumatology, Krems, Austria,

⁶ University Hospital Regensburg, Neurosurgery, Regensburg, Germany

Introduction: While MRI is the primary diagnostic tool for the diagnosis of spondylodiscitis, the role of [18F]-fluorodeoxyglucose ([18F]FDG) PET/CT is gaining prominence. This study aimed to determine the frequency of [18F]FDG PET/CT usage and its impact on the in-hospital mortality rate in patients with spondylodiscitis, particularly in the geriatric population. Material and Methods: We conducted a Germany-wide cross-sectional study from 2019 to 2021 using an open-access, Germany-wide database, analyzing cases with ICD-10 codes M46.2-, M46.3-, and M46.4- (‘Osteomyelitis of vertebrae’, ‘Infection of intervertebral disc (pyogenic)’, and ‘Discitis unspecified’). Diag-nostic modalities were compared for their association with in-hospital mortality, with a focus on [18F]FDG PET/CT. Results: In total, 29,362 hospital admissions from 2019 to 2021 were analyzed. Of these, 60.1% were male and 39.9% were female, and 71.8% of the patients were aged 65 years and above. The overall in-hospital mortality rate was 6.5% for the entire cohort and 8.2% for the geriatric subgroup (p < 0.001). The odds of in-hospital mortality closely mirrored the Patient Clinical Complexity Level (PCCL) categories, with lower categories showing reduced odds, As the complexity increased, so did the odds of mortality (PCCL 3-OR = 0.87, 95% CI: 0.78-0.97, p = 0.028; PCCL 4-OR = 1.97, 95% CI: 1.80-2.16, p < 0.001; PCCL 5-OR = 2.98, 95% CI: 2.68-3.33, p < 0.001; PCCL 6-OR = 6.07, 95% CI: 4.81-7.66, p < 0.001). Contrast-enhanced (ce) MRI (48.1%) and native CT (39.4%) of the spine were the most frequently conducted diagnostic modalities. Procedures associated with increased in-hospital mortality (OR > 1.00) included musculoskeletal ceCT (OR = 2.50; 95% CI: 1.67–3.74), abdominal ceCT (OR = 1.81, 95% CI: 1.65-1.99, p < 0.001), pelvic ceCT (OR = 2.16, 95% CI: 1.89-2.46, p < 0.001), and thoracic ceCT (OR = 2.00, 95% CI: 1.82-2.20, p < 0.001). When accumulated, all ceCT scans showed a significant association with in-hospital mortality (OR = 2.03, 95% CI: 1.90-2.17, p < 0.001). [18F]FDG PET/CT was performed in 2.7% of cases. CeCT was associated with increased in-hospital mortality (OR = 2.03, 95% CI: 1.90-2.17, p < 0.001). Cases with documented [18F]FDG PET/CT showed a lower frequency of in-hospital deaths (OR = 0.58, 95% CI: 0.18-0.50; p = 0.002). This finding was more pronounced in patients aged 65 and above (OR = 0.42, 95% CI: 0.27-0.65, p = 0.001). Conclusion: Despite its infrequent use, [18F]FDG PET/CT was associated with a lower in-hospital mortality rate in patients with spondylodiscitis, particularly in the geriatric cohort. This study is limited by only considering data on hospitalized patients and relying on the assumption of error-free coding. While a causal relationship between [18F]FDG PET/CT and in-hospital mortality cannot be established, several factors could contribute to this statistical correlation. Further research is needed to optimize diagnostic approaches for spondylodiscitis.

ID: 441

A166: The conundrum of spondylodiscitis treatment: the role of treatment strategies in readmission rates

Julius Gerstmeyer ^1,2,3 , August Avantaggio ² , Clifford Pierre ^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: The rising numbers in spondylodiscitis (SD) cases poses a significant challenge to healthcare systems worldwide. Treatment approaches commonly are inconsistent, without standardized algorithms and evidence-based guidelines. Readmission rates continue to be reported to be around 34.9%, highlighting opportunities for more consolidated management strategies. To date there is a knowledge gap relative to treatment, readmission rates and efficacy for different SD management strategies. This study aims to assess the 90-day all-cause readmission rates for SD and its different treatment pathways utilizing data from the Nationwide Readmissions Database. Methods: The 2020 National Readmissions Database, Healthcare Utilization Project (HCUP), was used to screen adult patients (> 18 years) using the primary diagnosis of SD by ICD-10 Codes (M46.2x, M46.3x and M46.4x). Demographic information, clinical data, and surgical treatment was extracted. Readmissions were identified using the VisitLink. The cohort was divided into two groups by treatment and subdivided by treatments upon readmission. Descriptive and comparative analysis, with a multivariate regression model to identify independent risk factors for readmission. Results: A total of 6,139 patients were included in our analysis, with 1,258 patients (20.5%) receiving surgical treatment. Overall, the all-cause 90-day readmission rate was 35%. Patients treated surgically had a significantly lower readmission rate over a longer timeframe compared to those treated non-surgically (29.3%; 41.65 days (±22.84) vs. 36.41%; 34.52 (±22.83)). Fifty-two patients (0.8%) received surgery at both index admission and readmission, with the longest mean time to readmission being 50.85 days (±24.27), which was significantly different from the 25.7% of patients who received non-surgical care during both admissions with the shortest mean interval to readmission being 34.16 days (±22.64). For both groups, a change in treatment was necessary in 8.4%. Compared to non-elective admission, surgical management at index admission was identified as a protective variable against readmission. Conclusion: SD management remains challenging and is applied inconsistently. The results of this study show that primary surgical treatment of SD resulted in a significantly lower readmission rates and a longer time interval until readmission compared to non-surgically treated. Surgery at initial admission was identified as a protective factors for readmission. These results suggest considering more standardized decision-making algorithms for SD management.

ID: 430

A167: Comparsion of hospital mortality and risk factors in conservative and surgical treatment of spondylodiscitis: nationwide analysis of 49,951 cases in Germany

Melanie Schindler ^1,2,3 , Jonas Krueckel ¹ , Josina Straub ¹ , Markus Rupp ¹ , Dietmar Dammerer ^2,3 , Volker Alt ¹ , Siegmund Lang ¹

¹ University Hospital Regensburg, Trauma Surgery, Regensburg, Germany,

² University Hospital Krems, Department of Orthopedics and Traumatologie, 3500 Krems, Austria,

³ Karl Landsteiner University of Health Sciences, 3500 Krems, Austria

Introduction: The treatment of spondylodiscitis presents a complex challenge in clinical practice. The decision between conservative and surgical therapy poses a significant clinical dilemma for patients and surgeons. The difficulty in comparing mortality rates often stems from small cohort sizes and the limitations imposed by selection bias. Therefore, with the current study, we aim to provide a comprehensive assessment of the risk factors for hospital mortality in patients treated conservatively and surgically. Methodology: In this study, data from January 2019 to December 2023 were extracted from the database of the german institute for the hospital remuneration system (InEK) GmbH. The german diagnosis-related groups (DRG) were used to analyze demographic data, therapy procedures, and accompanying diagnoses according to ICD-10 coding and procedures (OPS). The differences between conservative and surgical therapy were examined using the chi-square test. Odds ratios (OR) were used to analyze potential risk factors for hospital mortality. Results: In the analysis of 49.951 spondylodiscitis cases, a hospital mortality rate of 6.7% (n = 3.326) was observed. The patient cohort was predominantly male (n = 30,444; 61%). The diagnosis of spondylodiscitis was made in 0.60% of patients under 18 years of age (n = 302), 27.1% of patients aged 18-64 years (n = 13.528), 72.3% of patients aged 65 years and older (n = 36,118), and 30.6% of patients aged 80 years and older (n = 15,299). Overall, 62.9% of spondylodiscitis cases were managed conservatively, while 37.1% were treated surgically. Regarding age, there was a significantly higher hospital mortality rate with surgical compared to conservative treatment in patients aged 65 years and older (OR 1.66 vs. OR 0.75; p < 0.001) and 80 years and older (OR 1.89 vs. OR 0.75; p < 0.001). Conservatively treated spondylodiscitis with the presence of an intraspinal abscess showed an increased mortality risk (OR 1.9; p < 0.001). Comorbidities such as pneumonia, COVID-19 infection, systemic inflammatory response syndrome (SIRS), septic shock, acute renal failure, acute respiratory insufficiency, pleural effusion, atrial fibrillation, coronary artery disease, hypertension, diabetes mellitus, and acute hemorrhagic anemia were significantly associated with increased hospital mortality in both conservative and surgical therapy (p < 0.001). Conclusion: This study provides important insights into the current nationwide treatment of spondylodiscitis in Germany and the risk factors for hospital mortality in both conservative and surgical therapy. These findings underscore the need for careful risk assessment and individualized treatment decisions, especially in geriatric patients.

ID: 826

A168: Diagnosing pyogenic spondylodiscitis with next-generation sequencing: a comparative performance analysis with traditional diagnostic tests

Santhosh G. Thavarajasingam ^1,2 , Ahmed Salih ² , Jonathan Neuhoff ³ , Florian Ringel ¹ , Andreas Kramer ¹

¹ University Medical Center Mainz, Department of Neurosurgery, Mainz, Germany,

² Imperial College London, Imperial Brain and Spine Initiative, London, United Kingdom,

³ Berufsgenossenschaftliche Unfallklinik Frankfurt am Main, Center for Spinal Surgery and Neurotraumatology, Frankfurt am Mainz, Germany

Introduction: The incidence of pyogenic spondylodiscitis is rising, posing significant diagnostic challenges. Traditional methods, such as blood cultures, frequently fail to timely and accurately detect causative pathogens, leading to suboptimal treatment outcomes. This study introduces a novel approach using Next-Generation Sequencing (NGS) of cell-free DNA, aimed at enhancing diagnostic accuracy and improving patient management. Material and Methods: This prospective study at a tertiary care university hospital enrolled 13 patients suspected of having pyogenic spondylodiscitis. Participants were tested using both conventional blood culture and advanced NGS with the DISQVER platform, adhering strictly to ethical standards in compliance with the Helsinki Declaration. The study evaluated diagnostic efficacy, sensitivity, and specificity of the methods. Results: NGS demonstrated a significantly higher sensitivity (66.67%) compared to blood culture (33.33%) and was comparable to histopathology (83.33%). It also showed superior specificity (83.33%) relative to traditional diagnostics (blood culture: 66.67%, histopathology: 16.67%). NGS reduced the time-to-diagnosis, influencing therapeutic decisions, particularly in cases with inconclusive traditional results. Additionally, NGS identified pathogens in 38.46% of cases where traditional methods were limited, detecting pathogens such as Streptococcus pneumoniae, Parvimonas micra, and Enterococcus faecalis. The intraclass correlation coefficient (ICC) analysis highlighted the high diagnostic concordance of NGS with intraoperative swabs (ICC: 0.65), a stark contrast to the negative ICC values for blood cultures (-0.05) and histopathology (-0.1). The lack of statistical significance in these findings (p > 0.05) is likely due to the small sample size, with further data collection planned to confirm the initial findings. Conclusion: Early results support the integration of NGS as a standard diagnostic tool for managing pyogenic spondylodiscitis. By offering rapid and precise pathogen identification, NGS has the potential to transform the diagnostic landscape for complex infections, enabling more effective, tailored therapeutic interventions. Further research will validate these findings and potentially expand the use of NGS in diagnosing other complex infectious diseases.

ID: 1521

A169: Culture positive instrumentation sets in spine deformity surgery

Dejan Čeleš ¹ , Tanja Kanalec ¹ , Janez Mohar ^1,2 , Rihard Trebše ^{1 2}

¹ Orthopaedic Hospital Valdoltra, Ankaran, Slovenia,

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

Aim: Surgical site infection in spine surgery is a major complication that can have devastating health and socio-economic consequences. In the United States, it has resulted in cumulative medical expenditures of 1-10 billion dollars and 8000 deaths per year [1]. This study investigated the eventual colonization of surgical instruments during lengthy spine deformity surgeries. Method: We collected clean and unused instruments from open instrument sets at the beginning of surgery (incision time - IT); the second collection of clean and unused instruments left on open instrument sets was at the end of surgery (suture time - ST). Cultivation and molecular analysis were performed on the IT and ST instruments' sonication fluid. Before wound closure, we also collected tissue samples (TS) from above and below the thoracolumbar fascia. As a reference, agar gel plates (AG) were opened at the beginning of the surgery and collected at the end for airborne organisms. Laminar flow air temperature was stable in all cases, ranging between 18-19.5°C, with 43-45% humidity. Wilcoxon Signed Ranks Test was used for statistical analysis and paired sample comparison. Results: Samples from 17 paired sonications were analyzed. Among these cases, 12 AG and TS were collected as well. The mean surgical time was 273.23 minutes (range 200-335 minutes). In 2 cases, the collected instruments remained sterile. Sonication of instruments was microbiologically positive in 8/17 (47.1%) surgeries at the beginning of the operation (IT) and in 14/17 (82.4%) surgeries at the end (ST). The difference was statistically significant (p = 0.02) with more culture-positive instruments in the ST group. AG were positive in 11/12 cases – 91.7%. TS were positive in 3/12 cases – 25%. From 17 surgical cases, we isolated 61 bacterial colonies. Most commonly encountered were coagulase-negative Staphylococci (CNS) with S. epidermidis presented in 29.5% of isolates (18x), S. capitis in 14.6% (9x), S. haemolyticus in 13.1% (8x), S. hominis in 11.5% (7x), other bacteriae accounted for 31.1% (19x). Conclusions: Our study provided proof of significant airborne colonization of surgical instruments with mostly skin flora. We propose sequential opening of surgical sets depending on the stage of the procedure, sterile covering of opened surgical sets, and exchange of most used instruments. Causative bacteria can be a source of low-grade infection, persistent back pain, and pseudarthrosis [2,3].

References

1. Zhou et al Spine 2020;45(3):208-216

2. Zhang et al J Am Acad Orthop Surg Glob Res Rev 2022;6(3):e21.00259

3. Rupp et al BMC Infect Dis 2020;20(1):667

ID: 1018

A170: The association between low virulence organisms in lumbar spine and intervertebral disc structural failure: a prospective study

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

¹ Xuanwu Hospital Capital Medical University, Beijing, China

Introduction: Many factors may trigger intervertebral disc (IVD) structural failure (intervertebral disc degeneration (IDD) and endplate changes), including inflammation, infection, dysbiosis, and the downstream effects of chemical factors. Of these, microbiome dysbiosis has been considered as one of the potential reasons for disc structural failure. The exact relationships between microbial colonisation and IVD structural failure are not well understood. This prospective study aimed to investigate the impact of microbial colonisation and its location (such as skin, IVD, muscle, soft tissues, and blood) on IVD structural failure and corresponding low back pain (LBP) if any. Material and Methods: First, we searched four online databases for potential studies. The potential relationships between microbial colonisation in different sample sources (such as skin, IVD, muscle, soft tissues, and blood) and IDD and endplate change were considered as primary outcomes. Odds ratio (OR) and 95% confidence intervals (CI) for direct comparisons were reported. Grading of Recommendations Assessment, Development and Evaluation (GRADE) scale was used to assess the quality of evidence. Second, this study recruited 66 patients who underwent lumbar discectomy surgery for testing of gut microbiota, fecal metabolites, and IVD. 16S rRNA gene sequencing was used to detect the composition of gut bacteria, while liquid chromatography-mass spectrometry (LC-MS) was used to analyze metabolites in feces and intervertebral discs. Results: Twenty-five cohort studies met the selection criteria. Overall pooled prevalence of microbial colonisation in 2419 patients with LBP was 33.2% (23.6%-43.6). The pooled prevalence of microbial colonisation in 2901 samples was 29.6% (21.0%-38.9%). Compared with the patients without endplate change, the patients with endplate changes had higher rates of microbial colonisation of disc (OR = 2.83; 95% CI = 1.93-4.14; I2 = 37.6%; p = 0.108). The primary pathogen was Cutibacterium acnes which was present in 22.2% of cases (95% CI = 13.3%-32.5%; I2 = 96.6%; p = 0.000). 16S rRNA gene sequencing analysis revealed significant changes in the alpha and beta diversity of gut microbiota in patients with endplate alterations. Endplate degeneration group (Modic II type) is enriched with tumor bacteria. Metabolomics analysis revealed significant changes in tissue metabolites such as branched chain amino acid (BCAA) levels and their corresponding signaling pathways. Conclusion: This study found low-quality grade evidence for an association between microbial colonisation of disc with endplate changes. The primary pathogen was Cutibacterium acnes. Due to lack of enough high-quality studies and methodological limitations of this review, further studies are required to improve our understanding of the potential relationships and mechanisms of microbiota and IVD structural failure.

ID: 719

A171: External validation of the Spinal Infection Treatment Evaluation (SITE) Score: a single-center 19-year review of de novo spinal infections

Mohamed Soliman ¹ , Esteban Quiceno Restrepo ¹ , Alexander Aguirre ¹ , Asham Khan ¹ , Ali Khan ² , Megan Malueg 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: The authors assessed the predictive applicability of the Spinal Infection Treatment Evaluation (SITE) score in discerning between surgical intervention and medical management. This assessment represents the first external validation of the SITE score conducted in a cohort of patients with de novo spinal infections. This assessment represents the first external validation of the SITE score conducted in a cohort of patients with de novo spinal infections. Material and Methods: A comprehensive retrospective chart review was conducted, patients diagnosed with de novo spinal infections at a tertiary center between 2004 and 2023 were included. Data for calculating the SITE score were collected. Surgical intervention was advised for patients scoring 0-8 or exhibiting acute paralysis, bladder, or bowel dysfunction and optional for those scoring 9-12; medical treatment was recommended for patients scoring 13-15. Predictability of the score was scrutinized using the area under the curve (AUC) of the receiver operating characteristics (ROC) curve. Results: Stratifying patients based on medical and surgical management revealed that 27% underwent medical treatment alone and 73% required surgical intervention. Surgically managed patients exhibited a higher incidence of spinal stenosis with impingement of the spinal cord, with or without deformity when compared to non-surgical patients (38.7% vs. 22.2%, p = 0.04), had a lower SITE score (7.16 ± 2.39 vs. 8.2 ± 2.33, p < 0.001) and were more likely to have multilevel infection than patients who underwent medical management (59.2% vs. 33.3%, p < 0.001). Categorizing patients by the SITE score, the sensitivity of the score (using a threshold of 8) to predict surgical management was 68.6%, with a specificity of 59.3%. According to ROC curve, the SITE score exhibited an AUC of 0.66. Conclusion: Validation of the SITE score demonstrated poor external applicability for predicting medical versus surgical management in a tertiary center cohort of patients with de novo spinal infections. Further multicenter studies, incorporating additional variables and larger cohorts, are imperative to develop an optimal predictive tool.

OP20: Cervical Deformity 1

ID: 2607

A172: A classification system to assess cervical spine alignment and its association with sagittal spinal parameters: a multi-ethnic alignment normative study (MEANS)

Zeeshan Sardar ¹ , Roy Miller ¹ , Justin Reyes ¹ , Alexandra Dionne ¹ , Josephine Coury ¹ , Riley Sevensky ¹ , Matan Malka ¹ , Jean Charles Le Huec ² , Stephane Bourret ² , Kazuhiro Hasegawa ³ , Wong Hee Kit ⁴ , Gabriel Liu ⁴ , Dennis Hey Hwee Weng ⁴ , Michael Kelly ⁵ , Lawrence Lenke ¹

¹ Columbia University Medical Center New York, United States

² Bordeaux North Aquitaine Polyclinic, Bordeaux, France

³ Niigata Spine Surgery Center, Niigata City, Japan

⁴ National University Hospital (Singapore), Singapore, Singapore

⁵ Rady Children's Hospital, San Diego, United States

Introduction: Determining normative cervical spine alignment is crucial for guiding corrective surgery in spinal deformities. Prior studies correlate T1S-CL > 17 (cervical mismatch) as a threshold for defining deformity. Staub et al proposed a T1 Slope (T1S) formula predicting cervical lordosis (CL) with 40% accuracy and MAE of 7.8. A practical classification system for the cervical spine is still needed. This study assesses cervical mismatch rate and predictability of Staub's CL formula (CL = T1S - 16.5°) against linear regression, in an asymptomatic adult cohort as well as a new method of classifying cervical alignment. Methods: 468 asymptomatic adults (18-80 years) from 5 countries (USA, France, Japan, Singapore, Tunisia) formed the Multi-Ethnic Alignment Normative Study (MEANS). T1S and CL (C2C7°) were measured; cervical mismatch prevalence (T1S-CL > 17) was recorded. Positive values are kyphotic, and negative values are lordotic in this study. The validity of the Staub formula was assessed. MEANS cohort data was used for linear regression to derive a new predictive formula for comparison. A classification system was then developed using the new predictive formula and cSVA. Modifiers were added for segmental subaxial sagittal cervical alignment (SCA). CL was evaluated based on its comparison to predicted. Thresholds were set based on the average+2SD in the MEANS cohort for cSVA, and T1S. The threshold for SCA was based on the segment with the highest mean+2SD. The resulting classification system (Sardar-Miller Classification) is shown in Table 1. Radiographic parameters of the different alignment types were also compared. Results: Mean CSA was -0.42 (12.67)°, T1S was 23.0 (7.86), cSVA was 19.08 (9.75), and the highest mean SCA was 3.22 (4.77) which was of segment C4/C5. T1S-CSA was 22.58 (9.39) with an interquartile range of 9.5 - 35.7. Of all subjects, 71.4% exhibited cervical mismatch > 17°. Linear regression yielded CSA = -1.085(T1S) +24.52 (R² = 0.45, p < .0001) which was simplified to CSA = 24.5 - T1S. This MEANS-derived formula predicted CSA within 5° in 38.9% vs. 35% with an MAE of 7.64 vs. 8.99 when compared to Staub. 97% of the data was captured by Types 1A-B of the classification system, with the rest being captured by Types 2-4. Only 1% surpassed threshold for segmental kyphosis. Overall, age, CSA, OC2-CL, cSVA, T1S, and TK were statistically different amongst the groups (p < .01), without significant differences in lumbar or pelvic parameters. Conclusion: In this normative cohort, there was a high prevalence of cervical mismatch > 17°, suggesting that the previous definition of cervical deformity needs to be reassessed. A new classification for cervical alignment was thus developed using this normative cohort. There were significant differences in all cervical alignment parameters between groups, indicating clear distinction of cervical alignment between types.

ID: 2091

A173: Congenital atlantoaxial instability in children: surgical outcomes and pediatric specific intricacies

Karthigeyan Madhivanan ¹ , Pravin Salunke ¹

¹ Postgraduate Institute of Medical Education & Research (PGIMER), Department of Neurosurgery, Chandigarh, India

Introduction: The management aspects of pediatric congenital atlantoaxial dislocation (CAAD) differ from that of the adults. Softer bones, highly deformed joints, and fusion of multiple vertebral levels with potential for spinal growth impairment in younger age are unique challenges unique pertaining to this age group. We describe our experience and the challenges faced along with solutions, following multiplanar realignment and short-segment C1-C2 fusion in children with CAAD. Materials and Methods: A total of 56 pediatric patients with congenital AAD underwent C1-C2 posterior reduction and fixation. The oblique joints were drilled and remodeled to achieve multiplanar realignment. The baseline clinico-radiological data were compared with that of the follow up. Besides the surgical outcomes, we discuss the operative nuances and specific considerations in these children, different from their adult counterparts. Results: The series included 35 cases with irreducible and 21 cases with reducible AAD; the former had a higher incidence of bony anomalies, and the joints were more oblique and deformed. Nine patients had lateral angular dislocation, 3 had C1-C2 spondyloptosis and 5 had significant vertical dislocation. The C1-C2 joint drilling and manipulation was feasible in all patients. The operative techniques were modified to achieve an optimal bony purchase secondary to the drilling of relatively small bones and avoid screw pull out during intraoperative manipulation. Despite some challenges in few initial cases, realignment could be achieved in all. At follow up, there was a significant improvement in mJOA score in 95.8 % of cases, with 28 patients being independent. Conclusion: Children show relatively high oblique C1-C2 joints and therefore a frequent occurrence of spondyloptosis, severe vertical dislocation and lateral tilt. Despite the soft and small pediatric bones, a multiplanar realignment could be achieved by C1-C2 joint drilling and manipulation. The short segment C1-C2 fusion offers satisfactory clinical and imaging outcome in pediatric CAAD.

ID: 1737

A174: Five year trends in intraoperative neuromonitoring for cervicothoracic spine surgery

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

¹ Washington State University, Pullman, United States

² Virginia Mason Medical Center, Seattle, United States

³ University of Washington, Seattle, United States

Introduction: The utilization of intraoperative neuromonitoring (IONM) during spine surgery has been increasing in the United States. While studies have demonstrated this trend for the early 2000s, there is a lack of literature on patterns of IONM use during the most recent years. The purpose of this study was to investigate the trends and geographic variation in IONM use and cost from 2017 to 2021. Materials and Methods: This retrospective analysis utilized the National Inpatient Sample (NIS) from the Healthcare Cost and Utilization Project (HCUP) from 2017 to 2021. Patients undergoing cervical disc replacements (CDRs), cervical corpectomies, cervical decompressions and fusions, cervicothoracic decompressions, and hybrid procedures were isolated by ICD-10 PCS codes. Trends in the use of IONM and total hospital charge by geographic region were analyzed over the five-year period. Patient demographic data including age, sex, race, insurance type, income quartile based on zip code, and Elixhauser Comorbidity Index were collected. Results: A total of 145,986 patients were identified, of which 42,955 (29.4%) had IONM and 103,031 (70.6%) did not have IONM. There was an overall increase in IONM use from 2017 to 2021 in all regions, with New England having the greatest percent increase (75.7%) and the East North Central region having the smallest percent increase (7.9%). There was variation in IONM use among geographic regions, with the highest use by 2021 being in the South Atlantic region (7.1%) and the lowest use being in the East South Central region (1.2%). The national median hospital charge for procedures with IONM was $108,184.50 [68,491.50, 176,755.00] USD, compared to $89,214.00 [55,418.50, 150,060.00] USD for procedures without IONM. The median hospital charge increased in all regions during the five-year time period regardless of IONM use. By 2021, the highest median hospital charge was seen in the Pacific region ($175,392 USD with IONM, $147,778 USD without IONM) and the lowest was seen in the Northeast region ($80,0039 USD with IONM, $70,225 USD without IONM). Conclusion: This study demonstrates that IONM use and median total hospital charges have continued on an upward trend in the United States for the most recent years of data available from the NIS HCUP database. Geographic variation was seen in both the distribution of IONM use and the median total hospital charges. With the national median hospital charge for patients who had IONM use being around $18,970 USD higher than those without IONM, future studies are necessary to better understand the cost and utility of IONM.

ID: 2921

A175: Halo traction evaluation of craniocervical instability in hereditary connective tissue disorder patients: case series

Hussain Bohra ¹ , Joseph Maalouly ² , Neha chopra ¹ , Charmian Stewart ¹ , Ashish Diwan ¹ , Gayani Petersingham ^2,3 , Kevin Seex ⁴ , Prashanth Rao ^2,3,4,5

¹ Spine Service, University of New South Wales, Department of Orthopaedic Surgery, St George and Sutherland Clinical School, Sydney, Australia,

² Brain and Spine Surgery, Bella Vista, Australia,

³ University of New South Wales, Sydney, Australia,

⁴ Macquarie University Hospital, Department of Neurosurgery, Macquarie Park, Australia,

⁵ Norwest Private Hospital, Department of Neurosurgery, Sydney, Australia

Introduction: Cranio-cervical instability (CCI) is a condition commonly found in patients with connective tissue disorders such as Ehlers-Danlos Syndrome (EDS), leading to various symptoms. Assessing patients for surgical fusion as a treatment for CCI is challenging due to the complex nature of EDS-related symptoms. It is hypothesized that most symptom complexes related to EDS should be improved if the neurological and other manifestations were due to cranio-cervical abnormality/instability from EDS. This study aimed to evaluate the role of pre-fusion Halo traction in alleviating symptoms and determining suitable candidates for fusion surgeries. Material and Methods: EDS patients (n = 21) with neurological symptoms underwent halo traction between 2019 and 2022. Patients completed a CCI Questionnaire before and after the traction, reporting symptoms related to headache, vision, hearing, equilibrium, and performance. Symptom groups were assigned scores based on patient responses, with one point for each affirmative answer. Before and after scores were analyzed using paired t-test. Patients experiencing over 50% improvement in the majority of symptoms were considered for definitive fusion surgery. 16 out of 21 patients subsequently underwent fusion for CCI. Results: The average age of the patients was 35 years, with a female-to-male ratio of 20:1, consistent with existing literature. Significant improvements were observed in various symptom group after halo traction, including headache (57% improvement, p < 0.001), brainstem functions (71% improvement, p < 0.001), cerebellar functions (55% improvement, p < 0.001), hearing (63% improvement, p < 0.001), motor functions (51% improvement, p < 0.001), vision (60% improvement, p < 0.001), cardiovascular functions (46% improvement, p < 0.05), sensory and pain (53% improvement, p < 0.001), high cortical functions (54% improvement, p < 0.001), GI functions (52% improvement, p < 0.05), bladder functions (52% improvement, p < 0.05), and Modified Karnofsky score (30% improvement, p < 0.05). Conclusion: Halo traction could be an easy and effective way to screen patients for fusion surgery diagnosed with EDS presenting with cranio-cervical instability. It may provide significant relief in symptoms and provide an opportunity for surgeons to monitor patients the effect of a stable cranio-cervical junction before suggesting surgery. However, larger prospective or randomized studies are required for further evaluation.

ID: 2683

A176: Preliminary clinical efficacy of lateral mass interval release technique in the treatment of irreducible atlantoaxial dislocation

Deng Youwen ¹ , Liu Renfeng ¹

¹ The Third Xiangya Hospital of Central South University, Department of Spine Surgery, Changsha, Hunan, China

Introduction: Atlantoaxial dislocation is a severe craniocervical junction disorder, often caused by trauma, inflammation, or congenital abnormalities, leading to spinal cord compression and neurological dysfunction. In some patients, reduction becomes difficult due to fibrous tissue proliferation and joint adhesions, resulting in irreducible dislocation. Traditional reduction and fixation methods often encounter challenges such as incomplete reduction or recurrence in addressing these complex dislocations. The lateral mass interval release technique aims to improve reduction outcomes by releasing fibrotic structures around the joint. This study evaluates the preliminary clinical efficacy of this technique in enhancing reduction rates, postoperative stability, and neurological recovery. Material and Methods: This study included 30 patients with irreducible atlantoaxial dislocation treated with the lateral mass interval release technique between January 2019 and June 2023. Preoperative imaging confirmed the diagnosis, and satisfactory reduction was not achieved through external traction or other non-surgical interventions. Preoperative neurological function was assessed using the Japanese Orthopaedic Association (JOA) scoring system, with an average score of 8.4. The surgical approach involved posterior access, releasing the joint capsule and surrounding adhesions to achieve anatomical reduction of the dislocation. Postoperative reduction outcomes were confirmed through X-ray and CT imaging, with follow-ups at 1, 3, and 6 months to assess reduction status, joint stability, and neurological function recovery. Clinical efficacy was evaluated using JOA scores, imaging studies, and quality of life assessments (SF-36). Results: The lateral mass interval release technique successfully achieved anatomical reduction in all 30 patients, with a 100% reduction success rate confirmed by imaging. At the 6-month follow-up, 28 patients (93.3%) maintained good reduction without significant loss or recurrence of dislocation. Imaging showed that the atlantoaxial joint angles had returned to the normal range without significant bone structure damage. JOA scores significantly improved at 1, 3, and 6 months postoperatively, with an average score of 14.6 at 6 months (p < 0.01), indicating marked neurological function recovery. Quality of life assessments showed significant improvements in SF-36 scores, particularly in physical functioning, pain management, and daily activity capabilities at 3 and 6 months postoperatively. Only two patients experienced mild complications, both of which resolved within 3 months postoperatively. Conclusion: The lateral mass interval release technique demonstrates significant preliminary efficacy in the treatment of irreducible atlantoaxial dislocation, providing effective reduction and postoperative stability while significantly improving neurological function and quality of life. Initial results suggest that this technique holds promise in clinical practice, though further studies with larger sample sizes and extended follow-up periods are needed to confirm its long-term efficacy and safety.

ID: 1088

A177: Complications, morbidity, and mortality following corrective surgery for cervical deformity among geriatric cohorts

Andrew Kim ¹ , Yesha Parekh ¹ , Welsey Durand ¹ , Shay Bess ² , Douglas Burton ³ , Jeffrey Gum ⁴ , Munish Gupta ⁵ , Richard Hostin ⁶ , Khaled Kebaish ¹ , Michael Kelly ⁷ , Han Jo Kim ⁸ , Eric Klineberg ⁹ , Virginie Lafage ¹⁰ , Gregory Mundis ¹¹ , Paul Park ¹² , Peter Passias ¹³ , Themistocles Protopsaltis ¹⁴ , K. Daniel Riew ¹⁵ , Frank Schwab ¹⁰ , Christopher Shaffrey ¹³ , Justin Smith ¹⁶ , Christopher Ames ¹⁷ , Sang Hun Lee ¹ , International Spine Study Group (ISSG) ¹⁸

¹ Johns Hopkins Hospital, Baltimore, United States

² Presbyterian/St. Luke’s Medical Center and Rocky Mountain Hospital for Children, Denver, United States

³ University of Kansas Medical Center, Kansas City, United States

⁴ Leatherman Spine Center, Louisville, United States

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

⁶ Southwest Scoliosis and Spine Institute, Plano, United States

⁷ Rady Children's Hospital-San Diego, San Diego, United States

⁸ Hospital for Special Surgery, New York, United States

⁹ UTHealth Houston, Houston, United States

¹⁰ Lenox Hill Hospital, New York, United States

¹¹ Scripps Memorial Hospital, La Jolla, United States

¹² Semmes Murphey Clinic, Memphis, United States

¹³ Duke University Medical Center, Durham, United States

¹⁴ New York University, New York, United States

¹⁵ Columbia University, New York, United States

¹⁶ University of Virginia, Charlottesville, United States

¹⁷ University of California San Francisco, San Francisco, United States

¹⁸ International Spine Study Group, Denver, United States

Introduction: Corrective surgery for cervical deformity (CD) is challenging due to high risk of complications and morbidity as well as technical difficulties. With the increase of an aging population and utility of cervical spine fusions, there is a concomitant increase in the number of CD patients requesting corrective surgery. To our knowledge, this is the first study to analyze complication rates among different geriatric cohorts. Material and Methods: This is a retrospective review of a prospective, multicenter CD database. Operative CD patients with clinical and health-related quality of life (HRQL) data at 6-week follow-up were included in the study. CD patients were divided into 3 cohorts, > 75 vs. < 75 years of age, > 70 vs. < 70 years of age, and > 65 vs. < 65 years of age. Patient demographics, HRQLs, surgical characteristics, and complications (medical, surgical, neurological, revision surgery, mortality) were compared using Welch’s t-test and chi-square analysis. Logistic regression was performed to assess the impact of patient demographics on complication and revision surgery rates. Results: A total of 278 CD patients were analyzed. Mean age was 62.60 ± 11.32 years, with 57.19% (159/278) females. Number of levels fused, estimated blood loss, operative time, and length of showed no difference within the > 65, > 70, and > 75 years of age cohorts (p > 0.05). Baseline neck disability index (NDI) and numeric pain rating scale (NRS) neck were higher in < 65, < 70, and < 75 years of age groups within their respective cohorts (p < 0.05). The number of patients with complication were 82:71 in the < 65: > 65 years group, 113:40 in the < 70: > 70 years group, and 131:22 in the < 75: > 75 years group. Among complication types, patients < 65 years of age had higher rates of instrumentation complications (p = 0.049), and patients > 75 years had higher rates of dysphonia (p = 0.026) and musculoskeletal complications (p < 0.001). Logistic regression revealed age had no impact on complication or revision surgery rates (p > 0.05). History of osteoporosis was found to be a significant predictor of revision surgery, with odds of revision surgery increasing by 3.56 times (OR = 3.56, 95% CI [1.17, 10.89], p = 0.026). Conclusion: The present study demonstrates high complication rates following corrective surgery for CD more than 50% regardless of age criteria. There are no differences in surgical characteristics, complication rates, revision surgery and mortality when comparing patients among geriatric cohorts with different criteria including 65, 70 and 75 years old. Understanding high complication and morbidity risks associated with different ages will be important when discussing corrective surgery for CD in geriatric patients.

ID: 1300

A178: A novel classification of congenital cervicothoracic scoliosis: identification of coronal subtypes and their prognostic significance

Saihu Mao ¹ , Kai Sun ¹

¹ Division of Spine Surgery, Department of Orthopedic Surgery, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, China

Introduction: To propose a novel classification system for stratifying coronal curve patterns in congenital cervicothoracic scoliosis (CTS). Material and Methods: Type A: regional cervicothoracic deformity only disturbing the balance of head-neck-shoulder complex; Type B: cervicothoracic deformity with significant trunk tilt to the convex side; Type C: cervicothoracic deformity with a significant compensatory thoracic curve. The differences among different subtypes in deformity parameters and bony structures were compared to identify the causative factors predisposing to different subtypes. Results: 98 patients were classified into Type A (47 cases), Type B (31 cases), and Type C (20 cases). The Kappa test showed excellent reliability (Kappa value = 0.847) and reproducibility (Kappa value = 0.881) for this novel classification. The proportions of Klippel-Feil syndrome in Types B (71.0%) and C (85.0%) were significantly higher than in Type A (46.8%; all p < 0.05). Type A (66.0%) and Type B (71.0%) predominantly had their Hemivertebra (HV) at T3 or T4, while Type C (75%) mostly had HV at T1 or T2. Type B exhibited the most severe trunk tilt, head shift, neck tilt, head tilt, and coronal balance distance (all p < 0.05). Type C had the lowest T1 tilt and first rib angle despite the greatest cervicothoracic Cobb angle (all p < 0.05). Conclusion: This novel classification allows a better understanding of structural diversity and coronal compensatory mechanisms for the natural progression of different subtypes in CTS-HV. It can be of great help in determining the treatment strategy and standardizing academic communication for this rare clinical entity.

ID: 2710

A179: Does C1-C2 fixation offer superior outcomes than foramen magnum decompression in patients with Chiari malformations without instability?

Karthigeyan Madhivanan ¹ , Pravin Salunke ¹ , Puneet Malik ¹

¹ Postgraduate Institute of Medical Education & Research (PGIMER), Department of Neurosurgery, Chandigarh, India

Introduction: C1-C2 fixation without foramen magnum decompression (FMD) has been recently suggested for Chiari malformation (CM) without instability, and is controversial secondary to loss of C1-C2 movements. The claimed efficacy of this procedure over FMD, a well-established treatment modality for this entity has been scarcely evaluated. The objective was to prospectively assess the efficacy of C1-C2 fusion without FMD in Chiari patients without apparent atlantoaxial instability. Materials and Methods: Forty patients harbouring CM underwent C1-C2 distraction and fusion (without FMD). Pre-operative and follow-up clinico-radiological data were compared using Klekamp’s neurologic scale, visual analog scale, pBC2 index for ventral brainstem compression and Vaquero index for syringomyelia. Results: Twenty-eight patients (70%) improved in their neurological score and visual analog scale while 8 remained in the same status, 3 deteriorated and 1 expired at follow-up. The clinical improvement was not significantly associated with the severity of ventral cervicomedullary compression or presence of bony anomalies such as assimilated C1 arch, platybasia and basilar invagination despite the reduction in mean pBC2 index (7.9 vs 5.9). Syringomyelia reduced in 51.7%; Vaquero Index reduced at the follow-up (0.48 vs baseline, 0.38). Conclusions: The efficacy of C1-C2 distraction-fusion for CM without instability is not superior when compared with the reported outcomes following standard FMD. The ventral brainstem compression and associated osseous anomalies did not impact the clinical outcome in these patients.

ID: 1551

A180: Does coronal plane deformity matter for cervicothoracic kyphosis surgery? The incidence of cervical scoliosis and influence on the outcomes of cervical deformity surgery

Wesley Durand ¹ , Andrew Kim ¹ , Yesha Parekh ¹ , Shay Bess ² , Douglas Burton ³ , Jeffrey Gum ⁴ , Munish Gupta ⁵ , Robert Hart ⁶ , Richard Hostin ⁷ , Khaled Kebaish ¹ , Michael Kelly ⁸ , Han Jo Kim ⁹ , Eric Klineberg ¹⁰ , Virginie Lafage ¹¹ , Gregory Mundis ¹² , Paul Park ¹³ , Peter Passias ¹⁴ , Themistocles Protopsaltis ¹⁴ , Dan Riew ¹⁵ , Frank Schwab ¹¹ , Christopher Shaffrey ¹⁶ , Justin Smith ¹⁷ , Christopher Ames ¹⁸ , Sang Hun Lee ¹ , International Spine Study Group (ISSG) ¹⁹

¹ Johns Hopkins Hospital, Baltimore, United States,

² Presbyterian/St. Luke's Medical Center, Denver, United States,

³ Kansas University, Kansas City, United States,

⁴ Leatherman Spine Center, Louisville, United States,

⁵ Washington University in St. Louis, St. Louis, United States,

⁶ Swedish Neuroscience Institute, Seattle, United States,

⁷ Southwest Scoliosis and Spine Institute, Dallas, United States,

⁸ Rady Children's Hospital, San Diego, United States,

⁹ Hospital for Special Surgery, New York, United States,

¹⁰ University of Texas, Houston, Houston, United States,

¹¹ Lenox Hill Hospital, New York, United States,

¹² San Diego Spine Foundation, San Diego, United States,

¹³ Semmes Murphy Clinic, Memphis, United States,

¹⁴ New York University, New York, United States,

¹⁵ Columbia University, New York, United States,

¹⁶ Duke University, Durham, United States,

¹⁷ University of Virginia, Charlottesville, United States,

¹⁸ University of California, San Franciso, San Francisco, United States,

¹⁹ International Spine Study Group, n/a, United States

Introduction: Cervical deformity (CD) patients may have both cervical kyphosis (CK) and coronal plane cervical deformity, i.e., cervical scoliosis (CS). Although the deformity with the greatest influence on the clinical outcomes is CK, few studies, have focused on the complex condition of combined CK and CS and significance of CS in the correction of CD. This study sought to investigate 1) the incidence of combined CS/CK from a CD cohort underwent corrective surgery, 2) whether CK patients combined CS required more aggressive treatment and 3) had different preoperative and postoperative clinical outcomes compared to the CK only group. Material and Methods: This is a retrospective review of a prospective, multicenter CD database. Patients undergoing surgery for CD with cervical kyphosis (defined as C2-C7 (CL) > 10° kyphosis or C2-C7 sagittal vertical axis (SVA) > 4cm) were included. Patients with lumbar scoliosis > 10° were excluded. CS was defined as C2-C7 coronal Cobb angle as ≥ 10°. We compared surgical factors, pre-operative PROs as well as preoperative and follow-up radiographic data. Chi Square, Fisher’s Exact, and Wilcoxon-Mann-Whitney, and T-tests were utilized, as appropriate. Statistical significance was considered p < 0.05. Results: A total of 100 operative patients with cervical kyphosis were included (mean age 61.2 years, 51.5% female). 12 patients (12.0%) had combined CS with CK (CS/CK group) and 88 patients (88%) had CK only (CK group). Pre-operative maximum cervical coronal Cobb angle was 3.7° in the CK group and 17.1° in the CS/CK group. In the CS/CK group, this value improved to 10.1° (p < 0.0001), but CS > 10° was still present in 3 patients, with a mean correction percentage of 47.1% of initial scoliosis. Mean sagittal plane correction in the CK vs. CK/CS group was +7.6° vs. +14.9° (p = 0.54) in CL, -12.2mm vs. -7.4mm in C2-C7 SVA (p = 0.33), -13.9° vs. -11.1° in T1 slope (TS)-CL (p = 0.73), -0.4° vs. -1.6° in thoracic kyphosis (TK) (p = 0.57). The CK group had 13.8% anterior, 52.9% posterior, 33.3% anterior-posterior surgery, and the CS/CK group had 16.7% anterior, 41.7% posterior, and 41.7% anterior-posterior surgery (p = 0.77). 55.7% in the CK group underwent any type of osteotomy, versus 58.3% in the CS/CK group (p = 0.86). VCR or corpectomy was performed in 18.1% of the CK only group, and in 25.0% of the CS/CK group (p = 0.69). For the CK vs. CS/CK, the mean baseline NDI was 49.8 vs. 44.8 (p = 0.41), and 14.1 vs. 15.2 for mJOA (p = 0.16). Conclusion: Overall, 12.0% of CD patients also had combined cervical scoliosis. Post-operatively, the residual coronal plane deformity was > 50% of the preoperative deformity in the CK/CS group. However, the radiographic and clinical outcomes, surgical procedures of the CK group and the CK/CS group did not demonstrated significant differences. The present study firstly confirmed CK is the major component of CD and the correction of CK is the mainstay of corrective surgery of CD even combined with CS.

OP21: Intervention and Nonoperative

ID: 986

A181: Post-surgical virtual reality rehabilitation to augment recovery of hand dexterity after surgery for degenerative cervical myelopathy

Viprav Raju ¹ , Roxanne Hauer ¹ , Mohammad Ghassemi ² , Derek Kamper ² , Brian Schmit ³ , Aditya Vedantam ¹

¹ Medical College of Wisconsin, Milwaukee, United States,

² North Carolina State University, Raleigh, United States,

³ Marquette University, Milwaukee, United States

Introduction: Degenerative cervical myelopathy (DCM) is the most common cause of adult spinal cord dysfunction, with many patients experiencing impaired hand dexterity and diminished quality of life. Over 40% of people undergoing surgery for DCM report residual disability. Currently, there are no proven interventions to rehabilitate hand dexterity after surgery for DCM. Virtual reality training is a promising therapy for upper limb rehabilitation as it affords opportunities for repetitive practice with meaningful outcomes and facile adjustment of task challenge to promote learning. In this prospective, single-arm clinical trial, we investigated a novel virtual reality intervention to rehabilitate hand function for DCM patients after surgery. Methods: Post-surgical (within 1 year of surgery) DCM patients (n = 16) were recruited for a four-week intervention entailing three, one-hour sessions per week. During each training session, participants wore a sensor glove to train finger individuation in their self-reported more affected hand. Movement was guided by the Virtual Keyboard (VK system), which allowed participants to play a 5-key virtual piano keyboard by flexing their fingers, with a unique key associated with each digit. Task difficulty and speed were manipulated based on participant performance. The primary outcome measure was the Jebsen-Taylor Hand Function Test (JTHFT). Secondary outcome measures included quality of life indicators (Quickdash, EuroQol 5 Dimensions & Health score, SF36 physical and mental component scores [PCS & MCS]), myelopathy-specific scores (Myelopathy Disability Index - MDI and Modified Japanese Orthopedic Association scale - MJOA) and quantitative hand function tests (Nine-Hole Peg Test - 9HPT, Box and Block Test - BBT, and pinch strength). Outcomes were recorded at baseline and at 4 weeks after training. A paired t-test was used to determine differences between baseline and final follow-up scores. Results: Sixteen post-surgical DCM patients (mean (SD) age 68.12 (10.89) years, 12 men, 4 women) were prospectively enrolled at a mean of 4.36 (2.14) months post-surgery. Statistically significant improvement in the JTHFT (mean change -18.96s (15.88), p < 0.001) was noted at follow-up compared to baseline. Significant improvement in quality of life was noted for the EuroQol5 (mean change -1.13 (1.89), 95% CI [-4.84, 2.58], p = 0.031). Quantitative hand function tests showed significant improvement at final follow-up: BBT (mean change 4.94 (5.03), 95% CI [-4.98, 14.87], p = 0.0013), pinch (mean change 1.53 (1.31), 95% CI [-1.03, 4.09], p < 0.001), and 9HPT (mean change -2.92 (2.19), 95% CI [-7.21, 1.37], p < 0.001). Improvements in quantitative hand function tests (JTHFT, pinch strength, and BBT) exceeded the minimum clinically important difference (MCID). There were no adverse events associated with the training. Conclusion: Post-surgical DCM patients showed significant, sustained and clinically meaningful improvements in hand dexterity and quality of life after participating in a 4-week virtual reality hand training paradigm. The results demonstrate the efficacy of a targeted neurorehabilitative intervention to augment neurological recovery after surgery for DCM. Virtual reality hand dexterity training is a novel approach to target residual disability after surgery for DCM.

ID: 918

A182: Ionresonance vs clodronic acid in the conservative treatment of vertebral osteoporotic fracture. A comparative study on functional and radiological outcome

Luigi Meccariello ¹ , Vitaliano Muzii ² , Alessandra Alfieri ³

¹ AORN San Pio Hospital, Benevento, Italy,

² University of Siena, Siena, Italy,

³ AORN San Sebatiano and San Sebastiano, Caserta, Italy

Introduction: Approximately 200 million women worldwide have osteoporosis, representing one fifth of individuals aged over 50 years. Vertebral osteoporotic fractures (VOF) may predict the future occurrence of fractures and increase mortality. Treating underlying osteoporosis may prevent second fractures. The purpose of this study is to compare the effectiveness of ICR-like and clodronic acid in the conservative treatment of VOF. Material and Methods: A total of 66 elderly patients (20 males and 46 females), aged over 65 years, were enrolled, all suffering from VOF. The patients were divided into three groups: one group of patients (n = 20) was treated with dynamic corset and ICR-like therapy, another group (n = 20) with dynamic corset and clodronic acid, and a control group (n = 26) was managed with dynamic corset alone. The spinal orthosis was used for 90 days by all patients in the three groups, and all patients in the study groups underwent index treatment for 60 days. Outcome measures, during the clinical follow-up were visual analogue scale (VAS) for pain, Oswestry Low Back Pain Disability Questionnaire (OLBPDQ), Short Form 12 Health Survey (SF-12), and forced expiratory volume in the first second (FEV1). Regional kyphosis angle, Delmas Index, and height of the fractured vertebral body were also measured on standing full-spine X-rays. Follow-up intervals were 1, 3, and 6 months after injury. At 6-month follow-up, bone healing and correlation with bone marrow composition were assessed with X-ray and water-fat MRI. T- and Z- scores were also measured. Complications occurring during the 6-month follow-up were recorded. Results: There were no statistical differences between the three groups regarding fracture type, mean age, gender ratio, etc. At the 3- and 6-month follow-up, there was a significant difference (p < 0.05) in pain, disability, and respiration in favor of the ICR-like group. Complications were reported for 36 patients. They occurred in 16 patients (61.54%) of the control group, 3 patients (15%) in IRC-like group, and 7 (35%) in clodronic acid group, with a significative difference in favor of ICR-like group (p = 0.019). At sixth month, the second group presented better bone healing (p = 0.039), better functional recovery measured with Oswestry Low Back Pain Disability Questionnaire (p = 0.041), and Short Form 12 Health Survey (SF-12) (p = 0.039). At sixth months, the X-ray and MRI Index results were better for the second group (p = 0.029). Conclusion: The present study indicates that ICR-like or clodronic acid treatment in association with dynamic corset helps to reduce complications and improve outcomes after VOF in the elderly. The underlying concept is that proinflammatory processes can be attenuated by ionic exchange, balancing pH, reducing osteoclastic activity, and resulting in raised osteoblast levels. This is achieved through administration of clodronic acid or ICR-like, thereby promoting new bone formation. Biofeedback activation of back muscles is probably a key factor in improving functional outcome with dynamic orthosis.

ID: 601

A183: Enhanced scoliosis correction: the synergistic power of PSSE combined with an asymmetric scoliosis brace in adolescents

Anna Courtney ¹ , Sam Walmsley ¹ , Jack Choong ¹ , Connor Mumford ¹ , Finty Ilsley ² , Jason Bernard ³ , Tim Bishop ³ , Darren Lui ³

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

² Scoliosis SOS, London, United Kingdom,

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

Introduction: In-brace correction (IBC) is a key predictor of successful bracing outcomes in idiopathic scoliosis, with higher IBC linked to improved out-of-brace Cobb angle correction. Factors that may limit IBC include residual curve stiffness, suboptimal brace design, high BMI, non-compliance, and curve characteristics (e.g. length of curve). Physiotherapeutic Scoliosis-Specific Exercises (PSSE) are reported to improve curve flexibility. This study investigates the impact of PSSE on IBC. Material and Methods: This retrospective study analyses data from 54 patients with complete records over a 3-month period. Patients were grouped into those receiving bracing only (n = 25) and those receiving bracing combined with PSSE (n = 29). All participants met the SRS criteria for bracing and were fitted with their first scoliosis brace. All braces were assessed, modelled, and fit by a sole orthotist to ensure consistency. Skeletal correction was assessed using in-brace radiographs, with the primary outcome being the percentage reduction in Cobb angle. PSSE programmes were individually tailored to the patient's curve pattern and delivered by certified therapists, comprising up to 10 hours of face-to-face sessions and home exercises of 30 minutes, 4-5 times per week. Results: Preliminary analysis showed that the bracing plus PSSE group achieved greater IBC compared to the bracing-only group. In the bracing plus PSSE group, mean Cobb angle reduction in-brace was of 88%. In the bracing-only group, mean Cobb angle reduction in-brace was 75%. The results suggest that PSSE combined with asymmetric bracing enhances spinal flexibility and correction beyond bracing alone. Ongoing research will expand sample size to confirm statistical credibility of these findings and provide a clearer understanding of observed differences. Conclusion: Both groups benefited from bracing, but the addition of PSSE appeared to yield superior in-brace correction, suggesting PSSE as a valuable adjunct to bracing. This work supports the belief that PSSE may help address residual curve stiffness. Further research involving a larger sample size is required to validate these findings and explore the long-term effects on reduction/management of scoliosis progression.

ID: 1424

A184: Cervical retro-laminar injection for acute radiculopathy - A two years follow up

Morsi Khashan ¹ , Gilad Regev ² , Zvi Lidar ³ , Dror Ofir ² , Khalil Salame ³ , Uri Hochberg ⁴

¹ Tel Aviv Medical center - Tel Aviv university, Orthopedic Division, Neurosurgery, Tel Aviv, Israel,

² Tel Aviv Medical center - Tel Aviv University, Neurosurgery, Tel Aviv, Israel,

³ Tel Aviv Medical center - Tel Aviv University, Neurosurgery, Tel Aviv, Israel,

⁴ Tel Aviv Medical Center, Tel Aviv University, Orthopedic Division, Neurosurgery, Tel Aviv, Israel

Introduction: Cervical epidural steroid injections (ESI) are effective treatment for cervical radiculopathy. However, they are frequently avoided due to concerns regarding their safety (1,2). Recently, we reported that ultra-sound guided retro-laminar cervical injection (RLCB) are effective and safe procedure for treatment of cervical radiculopathy (3). In the current study, we provide a longer follow-up after RLCB in order to evaluate the lasting effects of the procedure, as cervical radiculopathy may recur or progress to a chronic condition. Methods: This is retrospective, comparative analysis of prospectively collected data of patients who underwent RLCB for cervical radicular pain between January 2021 to March 2023 at our clinic. All included patients had at least two years of follow up. The main out come measure was the change pain intensity following RLCB measured by numeric rating scale (NRS). Results: 130 patients were included in the study. A significant pain reduction was achieved after the. The mean NRS for the whole cohort decreased from 7.5 ± 3.1 to 4.3 ± 2.8 (p-value < 0.01) after receiving RLCB. This improvement in radicular pain intensity was maintained at two years following the procedure in 111 patient (81%). Fourteen patients (10.7%) eventually underwent surgical treatment. No major adverse events were reported, the most frequent complaint being of injection site soreness. Conclusions: Our findings suggest that the RLCB effectiveness in reducing pain in patients with cervical radiculopathy is sustained in the vast majority of patients for a prolonged period of at least two years following surgery.

References

1. Engel A, King W, Mac Vicar J. Standards Division of the International Spine Intervention Society. The effectiveness and risks of fluoroscopically guided cervical transforaminal injections of steroids: a systematic review with comprehensive analysis of the published data. Pain Med 2014; 15: 386-402.

2. Racoosin JA, Seymour SM, Cascio L, et al. Serious neurologic events after epidural glucocorticoid injection. The FDA’s risk assessment. N Engl J Med 2015; 373: 2299-301.

3. Hochberg, Uri et al. “A New Solution to an Old Problem: Ultrasound-guided Cervical Retrolaminar Injection for Acute Cervical Radicular Pain.” SPINE 46 (2021): 1370-1377.

ID: 2780

A185: Natural history of patients with mild degenerative cervical myelopathy treated non-operatively - A CSORN study

Nikolaus Kögl ¹ , Nathan Evaniew ² , Greg McIntosh ³ , Nicolas Dea ⁴

¹ Medical University Innsbruck, Neurosurgery, Innsbruck, Austria,

² University of Calgary, Department of Surgery, Calgary, Canada,

³ Canadian Spine Society, Markdale, Canada,

⁴ Vancouver General Hospital, Spine Department, Vancouver, Canada

Introduction: Degenerative cervical myelopathy (DCM) is the most common cause of spinal cord dysfunction in adults. Surgery is recommended in patients with moderate or severe DCM. However, the treatment of choice is uncertain in patients with mild DCM. While some authors report meaningful improvement with surgery in the mild category, the current literature is limited by the absence of a control non-operative group. The main goal of this study was to characterize the natural history of mild myelopathy and identify risk-factors for failure of non-operative management. Material and Methods: Data from the Canadian Spine Outcomes and Research Network DCM prospective cohort study were analyzed. For this analysis, only non-operatively treated mild DCM patients (mJOA 15-18) with clinical and radiographic follow-up at one year were included. The primary outcome was mJOA at 12 months post-enrollment. Secondary outcomes included various patient reported outcomes (NDI, NRS pain, EQ5D). A logistic regression was performed to assess potential risk factors for conservative treatment failure and crossover to the surgical group. Results: 146 mild DCM patients initially treated non-operatively were enrolled. Mean age was 58.1 (± 12.2) years and 53.4% were male. Mean mJOA at enrollment was 16.8 (SD 0.8), which did not change significantly at 1 year of follow-up: 16.6 ± 1.2 (p = n.s). No significant changes in PROs (NDI, SF-12 or EQ-5D, NRS) occurred after one year. Seventeen patients (11.6 %) crossed over to surgical treatment and 14 patients (9.6%) deteriorated by 2 or more mJOA points. Those who later underwent surgery, showed improved neck (5.0 ± 3.1 vs. 1.9 ± 1.4; p = 0.02) pain and stable mJOA post-operatively. Conclusion: Among patients with mild DCM treated non-operatively, we observed a cross-over rate of 11.6%. Patients who crossed-over had worse neurological function, health-related quality of life, neck and arm pain at baseline. Delayed surgery was associated with improvements in pain at 1-year follow-up. These findings support that non-operative management is associated with a low failure rate and conversion to surgery.

ID: 2061

A186: Optimising postoperative spine outcomes: an umbrella review of enhanced recovery after spinal surgery (ERASS) protocols

Daniel Sescu ¹ , Devika Dahiya ² , Laura Scamuzzo ³ , Stipe Corluka ⁴ , Sathish Muthu ⁵ , Samuel Cho ⁶ , Zorica Buser ⁷ , S. Tim Yoon ⁸ , Andreas Demetriades ⁹

¹ The School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Aberdeen, United Kingdom,

² Aberdeen Royal Infirmary, Department of Neurosciences, Aberdeen, United Kingdom,

³ Fondazione Policlinico Agostino Gemelli IRCCS, Department of Aging, Orthopaedic and Rheumatological Sciences, Rome, Italy,

⁴ University Hospital Centre Sestre milosrdnice, Spinal Surgery Division, Department of Traumatology, Zagreb, Croatia,

⁵ Government Medical College, Department of Orthopaedics, Karur, Tamil Nadu, India,

⁶ Icahn School of Medicine at Mount Sinai, Department of Orthopaedic Surgery, New York, United States,

⁷ NYU Grossman School of Medicine, Department of Orthopedic Surgery, Gerling Institute – NY Orthopedics, Brooklyn, United States,

⁸ Emory University, Department of Orthopedic Surgery, Atlanta, United States,

⁹ Royal Infirmary of Edinburgh, Department of Neurosurgery, AO Spine Knowledge Forum Degenerative, Edinburgh, United Kingdom

Introduction: Enhanced Recovery After Surgery (ERAS) protocols aim to accelerate recovery, reduce complications, and enhance surgical outcomes through a multimodal approach that spans preoperative, intraoperative, and postoperative phases. Core elements include patient education, optimized pain management, nutritional optimization, fluid control, and early mobilization. Given the complexity and extended recovery associated with spinal surgery, ERAS protocols hold significant potential to improve outcomes. Our aim was to conduct an umbrella review that synthesizes all published systematic reviews (SRs) on Enhanced Recovery After Spinal Surgery (ERASS) protocols. Material and Methods: This umbrella review followed PRISMA and PRIOR guidelines including SRs and meta-analyses (MAs) that evaluated the impact of ERAS protocols on spinal surgery outcomes. The search spanned databases such as Ovid MEDLINE, Embase, Cochrane Database of Systematic Reviews, Centre for Reviews and Dissemination and Web of Science from January 1990 to May 2024. Data extraction was independently conducted by two reviewers. The AMSTAR-2 and ROBIS tools were used to assess the quality and risk of bias in the included SRs. Meta-analytic estimates were recalculated from primary studies using random-effects models to account for heterogeneity, with Egger’s test used to assess publication bias. Results: Fifteen SRs, representing 224 primary studies and over 51,000 participants, were included in this umbrella review. Qualitatively, ERASS protocols consistently reduced hospital stays, postoperative complications, opioid use, and healthcare costs. Meta-analysis showed a reduction in hospital stay by 1.54 days (95% CI: 1.26-1.82), healthcare costs by $941.24 per patient (95% CI: $168.12-$2050.59), patient-reported pain scores by 0.27 (95% CI: -0.13, 0.66) and opioid consumption by 7.26 mg (95% CI: 3.70-10.82). Postoperative complication rate had a relative risk (RR) of 0.63 (95% CI: 0.53-0.74), while readmission rate was RR 0.79 (95% CI: 0.59-1.06). Study quality ranged from low to high (AMSTAR-2), with low risk of bias (ROBIS). Conclusion: This umbrella review is the first to evaluate ERAS protocols in spinal surgery, demonstrating significant reductions in complications, readmission rates, hospital stay, opioid use, and healthcare costs, ultimately enhancing patient outcomes. Overall, this review supports the widespread implementation of ERAS protocols in spinal surgery, with potential benefits for both patients and healthcare systems. Future studies should focus on standardizing ERAS interventions and addressing gaps in current research, particularly regarding long-term outcomes and patient satisfaction.

ID: 1485

A187: Are we “under-bracing” idiopathic scoliosis? Effectiveness of a providence night brace for curves under 25 degrees

Boulet Mathieu ¹ , Julie Joncas ¹ , Marjolaine Roy-Beaudry ¹ , Chemaly Olivier ¹ , Labelle Hubert ¹ , Jean-Marc Mac-Thiong ¹ , Brassard Felix ¹ , Stefan Parent ¹

¹ CHU Sainte-Justine, Montréal, Canada

Introduction: Observational studies have shown a significant progression rate (68%) in skeletally immature curves between 20 - 30°. Untreated immature curves have been previously shown to progress to a full-time bracing indication. Most bracing studies reported that conservative management is more effective with smaller and more flexible curves. The objective of this study was to determine if the 25° threshold for brace initiation should be revisited. Material and Methods: A prospective cohort of 166 idiopathic scoliosis was divided into two groups for comparison: 99 curves between 18° - 24° and 67 curves between 25° - 30°. Only skeletally immature patients were included (Risser 0 - 1 and 2). Results: For the cohort with early bracing (18° - 24°), mean age at initiation was 12.6 years (mean Risser 0.5 / Sanders 2.6). The average treatment duration with the night brace was 1.7 years. Mean Cobb angle did not significantly progress (22.2° at initiation of treatment vs. 22.5° after treatment (paired T-test p = 0.37). For the 25° - 30° cohort, mean age was 13.3 years at the brace initiation (mean Risser 0.8 / Sanders 3.7). This cohort spent an average of 1.2 years in a brace. Cobb angle means were 27.3° before, and 29.6° after treatment (paired T-test p = 0.017). Globally, patients were followed for a mean of 2.4 years until maturity at mean age of 15.3 (mean Risser 4.2 / Sanders 6.9). Curve improvement (decrease > 5°) was seen more often in the earlier cohort when compared to the classical bracing cohort (26.3% vs 11.9%). Of the patients with curve deterioration (increase > 5°), fewer patients had to be consented for surgery in the early start group (3% vs 9%). These differences were significant on a Chisquare test (p = 0.039). Conclusion: Night-time bracing in curves under the classical SRS bracing guidelines resulted in a greater proportion of patients with improved radiographic outcomes and a smaller proportion of patients undergoing surgery. An earlier night brace approach could be effective in reducing the burden of care when compared to a more delayed classical strategy often relying on full-time bracing.

ID: 2377

A188: Acceptance and commitment therapy (ACT) for patients with degenerative spinal conditions and maladaptive psychological processes: an observational study

Nathan Evaniew ¹ , Abdullah Alduwaisan ¹ , Victoria Smith ¹ , Tara Whittaker ¹ , Denise Eckenswiller ¹ , Rob Tanguay ¹ , Alex Soroceanu ¹ , Bradley Jacobs ¹ , Ken Thomas ¹ , Fred Nicholls ¹ , Ganesh Swamy ¹

¹ University of Calgary, Calgary, Canada

Background: Patients living with chronic pain often experience maladaptive psychological processes that include depression, somatization, kinesiophobia, pain catastrophizing, and anxiety. Spine surgery in the setting of maladaptive psychological processes can lead to poor outcomes, but intervention with Acceptance and Commitment Therapy (ACT), which is a specific form of Cognitive-Behavioral Therapy (CBT), may provide benefits. Our objective was to evaluate the effectiveness of ACT for patients with degenerative spinal disorders awaiting surgery. Methods: We performed a retrospective observational study of data that were collected in routine clinical practice at a single academic center. ACT was available as part of a multi-disciplinary optimization program, and referrals to ACT were at the discretion of the treating surgeons without standardized criteria. The following patient reported outcome measures (PROMs) were collected before and after ACT: Patient Health Questionnaire 9 item (PHQ-9) for depression, Patient Health Questionnaire 15 item (PHQ-15) for somatization, Tampa scale for Kinesiophobia (TSK), Pain Catastrophizing Scale (PCS), Generalized Anxiety Disorder (GAD-7), Post-Traumatic Stress Disorder (PTSD) Checklist, Injustice Experience Questionnaire (IEQ), and Pain Disability Index (PDI). Results: We included data from 63 patients who underwent ACT while awaiting spine surgery. ACT was associated with significant improvements for depression (mean change -3.3, SD 6.5, p < 0.01), somatization (-2.9, SD 4.1, p < 0.01), kinesiophobia (-6.1, SD 10.8, p < 0.01), catastrophizing (-9.9, SD 14.8, p < 0.01), anxiety (-2.1, SD 6.2, p < 0.01), injustice (-5.5, SD 8.5, p < 0.01), and pain disability (-6.4, SD 17.4, p < 0.01), but not PTSD (mean change -3.5, SD 14.3, p = 0.06). The proportions of patients that achieved the Minimum Clinically Important Difference (MCID) for each of these measures ranged from 27% to 52%, with the greatest effects being observed for catastrophizing, somatization, and kinesiophobia. Conclusion: Among selected patients, ACT prior to spine surgery was associated with significant improvements for many maladaptive psychological processes. These results suggest that implementation of ACT in clinical practice may be appropriate and that further research to understand effects on outcomes after surgery is warranted.

ID: 1733

A189: Enhancing scoliosis bracing: investigating the impact of in-brace correction exceeding 100% on skeletal outcomes, comfort and compliance

Anna Courtney ¹ , Sam Walmsley ¹ , Connor Mumford ¹ , Jack Choong 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: In-brace correction (IBC) is a key prognostic factor in bracing, with higher IBC associated with improved out-of-brace skeletal alignment. Comfort is crucial for consistent brace use, as wear duration also influences outcomes. While the industry standard for IBC is 50%, advancements in techniques, algorithms and brace design have enabled corrections that exceed 100%. The impact of IBC > 100% on skeletal outcomes, comfort, and compliance remains uncertain. This study retrospectively evaluates out-of-brace Cobb angle outcomes, comfort, and compliance during the first week, month, and full-time brace wear in patients with IBC > 100%. Material and Methods: Patients with IBC > 100%, who had grown 4 cm in truncal height and who had follow-up X-rays, were included. Braces were removed 24 hours before follow-up X-rays. Cobb angles were measured, and patients reported brace comfort (VAS scale) and compliance (percentage of prescribed 22 hours/day) retrospectively via an online survey. Complete data were available for eight female patients. Results: The mean age at brace initiation was 10.2 years. The initial mean Cobb angle was 33.4° (SD = 11.78), which corrected to -10.5° in-brace (SD = 6.19), achieving a mean correction of 134% (SD = 17.77%). Follow-up X-rays showed a mean out-of-brace Cobb angle of 17.5° (SD = 10.45), indicating significant skeletal correction in all patients (p = 0.013). During week one, 50% of patients achieved full-time wear, with the remainder achieving 75% compliance. By month’s end, 75% reached full-time wear, 12.5% reported 90% compliance, and 12.5% reported 75% compliance. Seven patients maintained 100% compliance throughout treatment, with one reporting they achieved 75%. VAS scores decreased from 4.5 (SD = 2.45) in week one to 1.6 (SD = 1.65) over treatment duration. Conclusion: IBC > 100% may enhance scoliotic correction, with a potentially statistically significant impact on follow-up, out-of-brace outcomes. High comfort and compliance rates support the use of over-corrective bracing in scoliosis management. Whilst long term follow up studies are necessary, these results suggest that orthotists should aim to achieve greater IBC when they are designing and fitting braces, likely only possible via asymmetric brace design.

OP22: Novel Technologies and Innovations 4

ID: 2408

A190: Novel filament-free 3D printable PEEK-HA-Mg2SiO4 composite material for spine implants

Si Jian Hui ¹ , Praveen Jeyachandran ² , Senthil Kumar ² , Jerry Fuh ² , Naresh Kumar ¹

¹ National University Health System, Singapore

² National University of Singapore, Singapore, Singapore

Background: Current ‘gold standard’ (Titanium) for spine implants have high young’s modulus which causes stress shielding and generates imaging artifacts. We aim to develop a novel filament-free 3D printable polyether ether ketone (PEEK)-hydroxyapatite (HA)-magnesium orthosilicate (Mg2SiO4) composite material with enhanced properties for use in tumour, osteoporosis and other spinal conditions. Our study evaluates the biocompatibility, imaging compatibility and printability of the material. Materials and Methods: Materials were prepared in three compositions, A: 75% PEEK, 20% HA, 5% Mg2SiO4; B: 70% PEEK, 25% HA, 5% Mg2SiO4; C: 100 % PEEK. Biomechanical properties were analyzed per ASTM standards and biocompatibility of the novel material was evaluated using indirect and direct cell cytotoxicity tests. Cell viability of the novel material was compared to PEEK and PEEK-HA materials. CT & MR imaging compatibility of the novel material cage were evaluated using a phantom setup. Results: Composite A resulted in cages and screws of optimal printability. Biocomposites exhibited linear elastic characteristic under bending load. Composite A enhanced cell viability up to around 30% compared to PEEK and PEEK-HA materials. Our material induces bioactivity thus avoiding the risk of delamination. Composite A cage and screws generated minimal/no artefacts on CT & MR imaging. Conclusion: Composite A demonstrated superior bioactivity and comparable imaging compatibility vs PEEK and PEEK-HA materials. Our biocomposite has Young’s modulus comparable to that of cortical bone, facilitating reduction in stress shielding. Filament-free printing also showed reduction in man-hours and costs savings during printing. Our material displays an excellent printability for manufacturing into spine implants with enhanced mechanical and bioactive property. This novel composite is predicted to improve osseointegration and reduce the chances of construct loosening/implant failure in MSTS and osteoporotic fixations.

Keywords: Spine, PEEK, 3D Printing, Implants, Magnesium orthosilicate

ID: 512

A191: The role of interleukin-6 as a biomarker in lumbar discectomy: implications for surgical outcomes and pain management

Esteban Espinoza ¹ , Manuel González ¹ , Alejandro Godoy ²

¹ Hospital San Camilo, San Felipe, Chile

² Clínica Alemana de Temuco, Temuco, Chile

Introduction: Interleukin-6 (IL-6), a key pro-inflammatory cytokine, has emerged as a significant biomarker in lumbar discectomy. This review explores IL-6's role in predicting postoperative recovery, assessing surgical magnitude, and informing therapeutic strategies for patients undergoing this procedure. Material and Methods: A comprehensive review was conducted through an extensive literature search in PubMed. Keywords such as “interleukin-6”, “lumbar discectomy”, “biomarker”, “postoperative outcomes” and “surgical magnitude” were used to identify relevant studies. Articles assessing IL-6 levels in the context of lumbar discectomy were included, covering studies on pathophysiology, postoperative outcomes, and surgical technique comparisons. Three authors independently reviewed and selected the most relevant articles based on their quality and clinical relevance. The studies were analyzed concerning their design, IL-6 measurement methods, and their relationship with postoperative clinical outcomes. Results: IL-6 levels strongly correlate with the extent of surgical injury, with higher levels indicating more invasive procedures. This cytokine peaks within 24 hours post-surgery, reflecting the acute inflammatory response, and typically returns to baseline by the seventh day. IL-6 levels also correlate with inflammatory markers like C-reactive protein (CRP) and creatine kinase (CK). The combined measurement of IL-6 and CK increases sensitivity in identifying tissue damage. Microendoscopic discectomy (MED) results in a smaller postoperative increase in IL-6 levels compared to open discectomy (OD), indicating less surgical trauma and potentially reduced postoperative pain. This is evidenced by a reduced inflammatory response, lower CRP levels, and shorter hospital stays for MED patients. Elevated IL-6 levels are associated with worse early postoperative outcomes, including higher pain scores and greater disability, suggesting slower recovery. Additionally, IL-6 serves as a sensitive early marker for surgical site infections, offering higher diagnostic accuracy than CRP and WBC. In lumbar herniated discs, elevated IL-6 levels suggest a localized inflammatory response. This inflammation plays a role in pain and may contribute to spontaneous herniation regression. However, while elevated IL-6 levels indicate local inflammation in lumbar disc herniation, there is no direct correlation between IL-6 levels and pain severity, suggesting that IL-6 may not be the sole factor in pain generation. Patients with low back pain due to spinal stenosis or degenerative disc disease exhibit higher serum IL-6 levels compared to those with disc herniation, indicating a broader role for IL-6 in these conditions. Higher IL-6 levels are significantly associated with chronic pain in lumbar disc herniation, although this does not directly correlate with pain severity. The presence of IL-6 and other cytokines in disc tissue and serum indicates an ongoing inflammatory process that may contribute to pain and tissue degradation. Conclusion: IL-6 is a valuable biomarker in lumbar spine surgery, correlating with surgical trauma, postoperative outcomes, and inflammation. Higher IL-6 levels indicate more invasive procedures and greater disability, while lower levels in less invasive techniques suggest reduced surgical stress. Its role in pain generation is complex, particularly in spinal stenosis and degenerative disc disease, making IL-6 crucial for optimizing patient care. Future research should focus on establishing standardized IL-6 thresholds for clinical use and exploring its application in personalized therapeutic strategies.

ID: 1739

A192: Utilizing deep learning-based early warning scores to forecast blood transfusion in lumbar spine procedure

Jung Sub Lee ¹ , Yoon Jae Cho ¹ , Tae Sik Goh ¹ , Hansol Kim ¹ , Minjun Choi ¹

¹ Pusan National University Hospital, Department of Orthopaedic Surgery, Busan, South Korea

Introduction: The deep learning-based early warning score (DEWS), an artificial intelligence (AI) assisted system, could be utilized in various clinical practices and for prevention of cardiac arrest. This study investigates the utility of DEWS in predicting intraoperative hemorrhagic risk in spinal surgeries, a critical factor for patient safety and surgical outcomes. Prior research predominantly focused on intraoperative determinants such as fusion levels and blood pressure to predict surgical blood loss. Our research expands this scope by examining the influence of both intraoperative variables and DEWS on blood loss during spinal surgeries. Additionally, we assess the correlation between DEWS scores and the necessity for transfusions in patients undergoing posterior lumbar spine surgery. Materials and Methods: This retrospective study encompasses 48 patients who underwent posterior lumbar spine surgery at Pusan National University Hospital. We collected demographic data, American Society of Anesthesiologists (ASA) scores, pre-operative and post-operative DEWS scores, and complete blood count (CBC) results as primary variables. The DEWS scoring system was employed pre- and postoperatively. Primary outcomes, including the volume of intraoperative blood loss and transfusion status, were meticulously recorded. Supplementary surgical parameters such as duration, fusion levels, estimated blood loss, and total concealed hemorrhage were also incorporated. Patients requiring transfusions (Hb < 7.0) were categorized as Group A, while those not requiring transfusions formed Group B. Results: Comparative analysis revealed no significant statistical difference in preoperative hemoglobin (Hb), hematocrit (Hct), and ASA scores between the groups. However, the preoperative DEWS score was notably higher in Group A (p = 0.032). Intraoperative fusion levels showed no significant variance (p = 0.073), but Group A exhibited longer surgery duration (p = 0.039). Postoperative Hb and Hct levels were significantly lower in Group A (p = 0.017, 0.031), and postoperative DEWS scores were elevated (p = 0.043). The study elucidates a substantial association between elevated pre- and post-operative DEWS scores and increased transfusion requirements. The Receiver Operating Characteristic (ROC) analysis between postoperative DEWS scores and transfusion necessity yielded an area under the curve of 0.752. Conclusion: Through rigorous retrospective analysis, we discerned the significant prognostic utility of postoperative DEWS scores in forecasting transfusion needs post-spinal fusion surgery. These findings underscore the imperative of integrating postoperative DEWS evaluations in clinical decision-making processes to enhance resource optimization and patient care during the perioperative phase.

Keywords: Artificial intelligence, Lumbar Spine surgery, blood transfusion, blood loss

ID: 2932

A193: An artificial intelligence-power platform to screen and monitor scoliosis via spinal movements

Nan Wu ¹ , Guilin Chen ¹ , Jianguo Zhang ¹

¹ Peking Union Medical College, Beijing, China

Introduction: Scoliosis is clinically diagnosed by measuring the Cobb angle when it exceeds 10 degrees on an anterior-posterior standing whole-spine X-ray. Scoliosis is a complex phenotype that may result from vertebral malformation, syndromic disorders, neuromuscular disorders, or idiopathic origins. The onset and specific risk factors of scoliosis remain unknown, making its prevention particularly challenging. Current screening methods for scoliosis are largely subjective and highly reliant on the examiner's expertise, including the forward bending test, Scoliometer, and Moiré topography. In response to these limitations, we have developed a novel screening strategy for scoliosis, integrating spinal movement analysis with artificial intelligence. Material and Methods: Strain sensors were employed to capture signals generated by spinal movements, including flexion, extension, bending, and rotation. Subsequently, a deep learning model was applied to process the strain time-series data. Initially, we utilized data from 62 patients diagnosed with adolescent idiopathic scoliosis, alongside age-matched controls (12 to 18 years), to develop this screening strategy. Additionally, we incorporated multi-center data to enhance the efficiency and accuracy of the approach. Results: Our study involved 62 patients with adolescent idiopathic scoliosis (AIS) and 44 healthy controls, matched for age and BMI. The median age was 14 years. Among the AIS patients, 54.5% presented with a single curve, 43.9% had a double curve, and one patient exhibited a triple curve. The Cobb angles of these patients ranged from 11 to 115 degrees. Initially, the strategy was applied to differentiate between healthy individuals and scoliosis patients, achieving a sensitivity of 100% and an accuracy of 88% for a single test. Subsequently, the strategy was used to assess the Cobb angle in patients. Patients were stratified into five groups based on their Cobb angle: 0-10, 10-20, 20-30, 30-40, and greater than 40 degrees. The strategy demonstrated a sensitivity of 97.22% and an accuracy of 83.1% for a single test. Conclusion: The integration of strain sensors with artificial intelligence enables the discrimination between healthy individuals and scoliosis patients. This approach can be further applied for scoliosis screening in daily life, while the enhanced algorithm can be utilized to monitor disease progression.

ID: 928

A194: Scoliosis with syrinx - A systematic review

Jim Francis Vellara ¹ , Nigil Palliyil ¹

¹ Amrita Institute of Medical Sciences, Spine Division, Orthopaedics, Kochi, India

Introduction: The incidence of associated scoliosis in patients with Syringomyelia ranges between 25%-85%. The risk of neurologic injury during deformity correction was thought to be substantially higher in the presence of associated Syringomyelia, and the recommendation was to perform prior neurosurgical treatment. However, in the past 2 decades, there has been a growing body of evidence to support single-stage posterior scoliosis correction without prior neurosurgical intervention. Material and Methods: The systematic review was conducted as per PRISMA guidelines using the search phrase (Syringomyelia OR Syrinx OR Chiari 1 Malformation) AND Scoliosis Surgery. Articles published in the English language between Jan 2003 and December 2023 were included. Case reports and case series with < 15 patients were excluded. Results: 10 articles that met the inclusion criteria were analysed. 369 patients (171 males, 198 females) with a mean age of 15.5 years with scoliosis associated with syringomyelia were included. The mean follow-up was 40.4 months (24-82.5). 58.7% of the patients had syringomyelia associated with a Chiari-1 malformation, while 41.3% had idiopathic syringomyelia. The average length of the syrinx was 9.4 vertebra (4.8-14). Pre-existing sensory deficits were found in 5.8% of patients, while 4.1% had mild motor deficits. 38.2% of patients underwent neurosurgical procedures (32.7% - foramen magnum decompression; 5.5% - syrinx shunting) before scoliosis correction. The mean pre-operative Cobb angle for the major curve was 63.20 which reduced to 20.50 post-operatively with the correction rate of 67.9%. The mean thoracic kyphosis was 38.40 which decreased to 29.60 post-operatively. Intra-operative neuro monitoring was performed in all patients with monitoring alerts (drop in MEPs) noted in 8.4% of patients. Patients with large syrinx (syrinx to cord ratio > 0.7) had a greater likelihood of needing prior neurosurgical decompression and also had less reliable intra-operative neuro monitoring. Three studies looked at the evolution of the syrinx after scoliosis correction which demonstrated a decrease in the size of the syrinx in 47.8% of patients. Neurological complications were seen in 1.4% of patients (3 patients with transient deficits, 2 patients with permanent deficits-1 root level, and 1 cord level deficit - ASIA C). This percentage is similar to the 0.69% - 1.06% range of complications reported in the literature for patients with adolescent idiopathic scoliosis (AIS) correction. Superficial surgical site infection was noted in 0.5% of patients. Screw malposition was noted in 2.4 % of patients, while junctional problems (PJF and DJK) were noted in 1.3% of patients. Conclusion: Surgical correction of scoliosis associated with syringomyelia can be safely undertaken with good clinical outcomes and minimal complications. A single-stage posterior scoliosis correction without prior neurosurgical decompression can be safely performed, in carefully selected patients with no overt progressive neurologic deficits.

ID: 1232

A195: Minimally invasive decompression vs open laminectomy for multilevel lumbar spinal stenosis: a systematic review and meta-analysis

Eshita Sharma ¹ , Kaike Eduardo da Silva Lobo ² , Ayesha Ayesha ³ , Paweł Łajczak ⁴ , Beatriz Pomianoski ⁵ , Yan Silva ⁶

¹ David Geffen School of Medicine, Los Angeles, United States,

² State University of Pará, Belém, Brazil,

³ Shifa College of Medicine, Islamabad, Pakistan,

⁴ Faculty of Medical Sciences in Zabrze, Medical University of Silesia, Katowice, Poland,

⁵ Universidade Nove de Julho, São Paulo, Brazil,

⁶ Hospital Ortopédico do Estado, Department of Orthopedic Surgery, Salvador, Brazil

Introduction: Lumbar spinal stenosis is a common spinal condition. Surgical intervention is often the treatment choice. The recent development of endoscopic techniques is posing questions on when is better to approach a multilevel stenosis with an endoscope and when the open approach could be a better choice. Two primary surgical approaches for treating lumbar spinal stenosis are open laminectomy surgery (OLS) and minimally invasive decompression (MID) with or without an endoscopic approach. Therefore, the aim of this meta-analysis is to compare the MID with OLS. Material and Methods: We systematically searched PubMed, Embase, and Cochrane Central for randomized controlled trials (RCTs) and observational studies comparing patients with multilevel lumbar stenosis treated with MID with and without an endoscopic approach, versus OLS. Primary outcomes were length of hospital stay (LHS), operative time (OT), complication rate (CR), intraoperative blood loss (IBL), reoperation due to recurrency (RDR) and low back pain 1 year after surgery (LBP). 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 3695 articles screened, a total of 4 studies and 618 patients were included, of whom 291 (47%) were treated with MID and 327 (53%) were treated with OLS. There were no significant differences between the groups in OT (MD = 7.86, 95% CI [-25.28, 41.01], p = 0.64, I² = 96%), CR (OR = 0.72, 95% CI [0.04, 14.73], p = 0.83, I² = 80%), RDR (OD = 0.34, 95% CI [0.06, 1.860], p = 0.21, I² = 0%) and LBP (MD = -0.38, 95% CI [-1.83, 1.08], p = 0.61, I² = 64%). However, the LHS was shorter when patients were treated with MID compared with OLS (MD = -3.26, 95% CI [-6.38, -0.13], p = 0.04, I² = 98%), which can reduce the risk of infections. Furthermore, IBL was reduced in MID in contrast with OLS (MD = -55.20, 95% CI [-105.73, -4.67], p = 0.03, I² = 95%), decreasing the need for transfusions and complications. Only the RDR presented a low heterogeneity while the rest of outcomes conferred a high heterogeneity. Conclusion: Our study showed important statistical differences between the groups analyzed, this is probably due to the lack of standardized approach and decompression techniques used across the studies. MID offers advantage in terms of recovery and intraoperative blood management when compared to OLS, which presents a safer treatment of lumbar spinal stenosis.

ID: 914

A196: Framework for the adoption of enabling technologies for improved outcomes in spine surgeries

Sathish Muthu ^1,2,3 , Swaminathan Ramasubramaniam ⁴ , Madhan Jeyaraman ⁵ , Roger Härtl ⁶ , Javad Tavakoli ⁷ , Samuel Cho ⁸ , Laura Scamuzzo ⁹ , Hardeep Singh ¹⁰ , Philip Louie ¹¹ , Andreas Demetriades ¹² , Patrick Hsieh ¹³ , Stipe Corluka ¹⁴ , Yabin Wu ¹⁵ , Xiaolong Chen ¹⁶ , Hai Le ¹⁷ , Gianluca Vadalá ¹⁸ , Waeel Hamouda ¹⁹ , Zorica Buser ²⁰ , Jeffrey C. Wang ¹³ , Hans-Jörg Meisel ²¹ , S. Tim Yoon ²² , Amit Jain ²³

¹ Government Medical College & Hospital, Department of Orthopaedics, Karur, India,

² Karpagam Academy of Higher Education, Department of Biotechnology, Coimbatore, India,

³ Orthopaedic Research Group, Department of Spine Surgery, Coimbatore, India,

⁴ Government Omandurar Medical College, Department of Orthopaedics, Chennai, United States,

⁵ ACS Medical College and Hospital, Department of Orthopaedics, Chennai, India,

⁶ Weill Cornell Medicine, Department of Neurosurgery, New York, United States,

⁷ RMIT University, Department of Biomedical Engineering, Melbourne, Australia,

⁸ Icahn School of Medicine at Mount Sinai, Department of Orthopedic Surgery, New York, United States,

⁹ Fondazione Policlinico Universitario Agostino Gemelli, Department of Spine Surgery, Rome, Italy,

¹⁰ University of Connecticut Health Center, Department of Orthopaedic Surgery, Connecticut, United States,

¹¹ Virginia Mason Medical Center, Center for Neurosciences and Spine, Seattle, United States,

¹² Royal Infirmary of Edinburgh, Department of Neurosurgery, Edinburgh, United Kingdom,

¹³ Keck School of Medicine, Department of Neurological Surgery and Orthopaedics, California, United States,

¹⁴ University Hospital Centre Sestre milosrdnice, Department of Traumatology, Zagreb, Croatia,

¹⁵ AO Spine, Research Department, Davos, Swaziland,

¹⁶ Xuanwu Hospital Capital Medical University, Department of Orthopaedics, Beijing, China,

¹⁷ UC Davis Medical Center, Department of Orthopaedic Spine Surgery, California, United States,

¹⁸ Università Campus Bio-Medico di Roma, Reaserch Unit of Orthopaedic and Trauma Surgery, Rome, Italy,

¹⁹ Kasr Alainy Faculty of Medicine, Department of Neurosurgery, Cairo, Egypt,

²⁰ 23.NY Orthopedics (Gerling Institute), New York, United States,

²¹ BG Klinikum Bergmannstrost, Hallee, Germany,

²² Emory University, Department of Orthopaedics, Atlanta, United States,

²³ Johns Hopkins University, Department of Orthopaedic Surgery, Baltimore, United States

Introduction: The integration of advanced technologies into spine surgery has heralded a transformative shift in medical practices. We aim to investigate the integration and impact of enabling technologies, such as augmented reality, virtual reality, mixed reality, navigation, robotics, and artificial intelligence within the domain of spinal surgery. Methods: We made a literature review for articles that examined the progression of adoption from initial to subsequent adopters. We also analysed the key determinants that influence adopting these technologies into clinical settings. These include cost-effectiveness, ease of integration, patient acceptance, learning curves, and availability of training resources. Based on the available data a suggestion has been made on the adoption framework for clinical utility. Results: These technological advancements have the potential to transform surgical practice, offering improved precision and efficiency. The journey toward a widespread adoption presents challenges, which include the financial implications, the necessity for specialized training, and complexities associated with integration. To navigate these hurdles, the study proposes recommendations aimed at improving cost-efficiency, the streamlining of technology integration, investing in professional development, and nurturing a culture of innovation and research. Conclusions: A framework has been established for the evaluation and integration of state-of-the-art technologies in spinal surgery, thereby maximizing their potential impact on surgical outcomes and patient welfare. Recent technological advancements in spine surgery aim to improve the precision, efficiency, and safety of care delivered to patients presenting with spine pathology. As we navigate the complex landscape of integrating these technologies into clinical settings, it is evident that a multifaceted approach, considering cost-benefit analyses, integration, workflow, patient acceptance, learning curves, and the availability of training and support, is crucial for successful evaluation and adoption. As we create a reproducible method to responsibly adopt new technologies, we can build on these algorithms to further improve patient care in the future. One must not forget that these are only complementary and not competing technologies in assisting the surgeon at delivering the best possible care efficiently.

ID: 2727

A197: Evaluation of the accuracy of robotic-guided pedicle screw placement in Hong Kong’s pioneering cohort of 209 screws

Wai Kiu Thomas Liu ¹ , Kai Chun Augustine Chan ² , Kenny Yat Hong Kwan ²

¹ Queen Mary Hospital, Department of Orthopaedics and Traumatology, Hong Kong, Hong Kong,

² University of Hong Kong, Department of Orthopaedics and Traumatology, Hong Kong, Hong Kong

Introduction: Precise placement of pedicle screws is crucial in spinal surgery to ensure stability and fusion. Robotic systems, leveraging advanced imaging and preoperative planning, aim to enhance accuracy and reduce human error. This study is the first to evaluate robotic-assisted spinal surgery (RASS) in Hong Kong. Material and Methods: This retrospective cohort study assessed the early efficacy of RASS for pedicle screw placement. The study included the first 15 patients who underwent robotic-assisted posterior spinal instrumentation and fusion (PSF) with Mazor X^TM Robot from October 2023 to March 2024 at our institutions. 7 patients had AIS and 8 had degenerative spinal condition. PSF was performed on all patients. All patients with AIS underwent open PSF without anterior column fusion. Overall, there were 5 cases of MIS and 10 cases of conventional open (CO) surgery. Results: 209 screws were inserted under robotic guidance. 189 and 20 screws were inserted in CO and MIS surgery, respectively. 23 screws (9.9%), out of 232 attempts of robotic-assisted insertion, required conversion to free-hand technique after intraoperative failure to insert the screws by robotic assistance with Mazor X registration and navigation. In addition, another four screws (1.9%, 4/209), that were inserted by robotic assistance, were malpositioned with no associated neurological complication. All malpositioned screws occurred in CO operation, however, no significant difference in the incidence of screw malpositioning was demonstrated between CO (4/189, 2.1%) and MIS (0/20, 0%) approaches (p = 0.510), or between AIS (2/148, 1.4%) and degenerative (2/61, 3.3%) patients (p = 0.360). The incidence of free-hand conversion was higher in AIS cases (20/168, 11.9%) compared to degenerative cases (3/64, 4.7%) (p = 0.100), and higher in CO (23/212, 10.8%) than in MIS (0/20, 0%) surgery (p = 0.121), however, the results were not statistically significant. The mean time per screw insertion was 5.79 minutes (SD ± 2.64; range: 2.0-18.25 mins). Screw insertion with CO approach (5.21 mins) required a significantly shorter time than that with MIS approach (11.75 mins) (p < 0.001). Screw insertion in AIS cases (4.93 mins) was also significantly faster than that in degenerative cases (8.00 mins) (p < 0.001). According to the regression analysis, no correlation was found between the time required to insert one pedicle screw and the cumulative screws inserted at our institutions (p = 0.801) or the number of cases (p = 0.685), respectively. Conclusion: The introduction of robotic systems in spinal surgery in Hong Kong shows promising results in enhancing the accuracy and efficiency of pedicle screw placement. Navigated robotic guidance achieved a successful pedicle screw positioning rate of 98.1%, with only one case requiring revision surgery and four screws (1.9%) being malpositioned. Higher risk of free-hand conversion was likely associated with AIS, due to the intrinsic challenges posed by the deformity and dysplastic pedicles. Although the MIS approach required longer screw insertion times compared to the CO approach, the early results of RASS with MIS, especially in terms of the accuracy of screw placement, are promising. As the first study of its kind in Hong Kong, it highlights the potential benefits of robotic assistance in both open and MIS spinal surgery.

ID: 1034

A198: The influence of professional membership in spine oncology research: a bibliometric analysis of AO spine knowledge forum tumor members

David Kurland ¹ , Daniel de Souza ¹ , Arjun Sahgal ² , Charles Fisher ³ , Laurence Rhines ⁴ , Stefano Boriani ⁵ , Ziya Gokaslan ⁶ , Ilya Laufer ¹

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

² Sunnybrook Health Sciences Centre, Radiation Oncology, Toronto, Canada,

³ University of British Columbia, Orthopedics, Vancouver, Canada,

⁴ MD Anderson Cancer Center, Neurosurgery, Houston, United States,

⁵ University of Bologna, Orthopedics, Bologna, Italy,

⁶ The Warren Alpert Medical School of Brown University, Neurosurgery, Providence, United States

Introduction: The primary objective of this study was to use bibliometric analyses to characterize publication trends in spine oncology research among a group of contemporary leaders in the field. We examined the impact of membership in a formalized professional organization on author, institutional, and international collaboration and identified influential articles and key contemporary topics. Material and Methods: We queried the Web of Science database for all publications authored by members of the AO Spine Knowledge Forum Tumor (KF Tumor, N = 64). The resulting publication metadata were exported, and statistical and bibliometric analyses were performed using various Python packages. Additionally, a Reference Publication Year Spectroscopy (RPYS) analysis was conducted to identify the historical works disproportionately cited by KF Tumor authors, revealing the influential articles that shaped their research. Results: Our query returned 9,294 articles, of which 4,619 were identified as specifically related to spinal oncology through an algorithmic analysis of titles, abstracts, and keywords. These works, published between 1980 and 2024, included contributions from 17,795 authors and demonstrated substantial growth following the establishment of AO Spine (2003) and KF Tumor (2010). Co-authorship among KF Tumor members, unique institutional affiliations per article, and international collaboration increased over time, contemporaneously with the formation of KF Tumor. A positive association was found between the number of KF Tumor authors on a publication and the impact factor of the source journal. The RPYS analysis identified the key influential articles that shaped KF Tumor authors' research, and zero-shot topic modeling highlighted active areas of research within the dataset. Conclusion: This study characterized key trends in collaboration, publication impact, scholarly origins, and research focus within the body of work produced by KF Tumor members. The findings suggest that the formalization of researcher relationships through the professional organization was associated with increased research output and collaboration. Through the development, support and maintenance of the Knowledge Forum model, the AO appears to play a key role in the generation and translation of critical spine-related knowledge worldwide. The methods used in this study are easily replicable and could be applied to investigate the impact of other professional organizations across various fields.

OP23: Imaging and Diagnostics 2

ID: 2179

A199: The role of prone MR imaging in spinal cord re-tethering

Laura-Nanna Lohkamp ¹ , Rita Nguyen ² , Linda Heier ³ , Alexandra Giantini Larsen ⁴ , Jeffrey P. Greenfield ⁴

¹ Thunder Bay regional Health Sciences Centre, Neurosurgery, Thunder Bay, Canada,

² Weill Cornell Medicine, Neurosurgery, New York, United States,

³ Weill Cornell Medicine, Diagnostic Radiology, New York, United States,

² Weill Cornell Medicine, Neurosurgery, New York, United States

Objective: Retethering of the spinal cord is a rare condition after surgical detethering, which can be a challenging diagnosis in supine Magnet Resonance Imaging (sMRI). Prone MRI (pMRI) has shown comparative advantages in primary tethered cord syndrome (TCS). The objective of the study was to determine the role and diagnostic value of pMRI in the specific context of post-operative spinal cord re-tethering. Material and Methods: Retrospective review of patients with TCS who underwent primary and secondary cord release at New York Presbyterian Hospital Weill-Cornell Medical Center between 2022 and 2024. MRI results, intra-operative findings, and timepoint of retethering after the index procedure were retrieved from the charts. The diagnostic accuracy of pMRI versus sMRI was assessed via identification of conus level, filum appearance, and cord mobility and compared to the intra-operative findings. Results: 13 patients were included in the study (range 8 to 60, median 29 years) with female predominance (77%). Ten patients initially met sMRI criteria for TCS with confirmation of radiographic findings, and pMRI versus sMRI was utilized to identify re-tethering in 9/10 patients, who underwent a total of 23 combined sMRI and pMRI. The diagnostic accuracy of pMRI in these patients was 100% versus 61% in sMRI with regards to re-tethering. The most conclusive parameter for re-tethering was absence of ventral motion of the conus medullaris during pMRI whereas the most common source of retethering were nerve roots or previously cut fatty filums with dorsal retethering. Conclusions: The standardized utilization of prone MRI for diagnosis tethered and retethered spinal cord is supported by an increased diagnostic accuracy and sensitivity compared to sMRI. Bigger cohort studies are required to confirm these results.

ID: 2650

A200: Imaging study of intervertebral disc calcification based on MRI-based Vertebral Disc Quality score (VDQ)

Junxiao Su¹, Yang Yang¹, Hui Zhang¹

¹ Gansu Provincial Hospital, Lanzhou, China

Introduction: MRI is one of the most accurate methods for diagnosing lumbar disc herniation, but it cannot determine whether disc calcification has occurred. Since disc calcification affects the choice of surgical methods and increases the risk of surgical complications, this study plans to establish an MRI-based Vertebral Disc Quality Score (VDQ) to assess the occurrence of disc calcification and evaluate its effectiveness and reliability. Material and Methods: This retrospective study included 42 patients (32 males and 10 females, average age 52.3 ± 9.2 years) who underwent surgical treatment for lumbar disc herniation (L5/S1) with disc calcification at our medical institution from June 2021 to June 2022. Using propensity score matching, 84 patients (64 males and 20 females, average age 52.1 ± 8.9 years) who underwent surgical treatment for lumbar disc herniation (L5/S1) without disc calcification during the same period were selected as a control group. All patients had complete preoperative CT and MRI data. The average signal intensity of the herniated disc at the L5/S1 segment and the cerebrospinal fluid behind the L3 vertebral body was measured on T1-weighted MRI images of the lumbar spine. The ratio of the signal intensity of the herniated disc to that of the cerebrospinal fluid was defined as the Lumbar Vertebral Disc Quality Score. The t-test was used to compare the VDQ scores between the two groups, and Logistic regression analysis was used to determine the correlation between VDQ scores and disc calcification. The area under the receiver operating characteristic curve (ROC) was calculated to evaluate the VDQ score as a predictor of disc calcification, and the cutoff value was determined based on the Youden index. Results: After matching the two groups based on propensity scores, there were no statistical differences in baseline data such as age, gender ratio, BMI, symptom duration, and surgical segment. The VDQ score of the herniated disc at L5/S1 in the case group was significantly lower than that in the control group (1.51 ± 0.21 vs. 1.81 ± 0.22, p < 0.001). Logistic regression analysis showed a significant negative correlation between the VDQ score of the herniated disc at L5/S1 and the occurrence of disc calcification (OR = 0.002, p < 0.001). The ROC curve analysis showed an AUC of 0.836, and when the VDQ score was 1.618, it could distinguish the presence of disc calcification with a sensitivity of 82.1% and a specificity of 69.0%. Conclusion: This study of patients with L5/S1 disc herniation showed that the MRI-based VDQ score can be used to assess the occurrence of disc calcification. Patients with disc calcification had significantly lower VDQ scores than those without disc calcification, and there was a negative correlation between VDQ scores and disc calcification.

ID: 2392

A201: Fusion assessment consensus exists between clinicians and AI assisted spinal motion analysis technology

Christopher Martin ¹ , S. Tim Yoon ² , Yabin Wu ³ , John Hipp ⁴ , Trevor Grieco ⁴ , Zorica Buser ⁵

¹ Department of Orthopaedic Surgery, University of Minnesota, Minnesota, United States,

² Department of Orthopaedic Surgery, Emory, Atlanta, United States,

³ AO Foundation, Davos, Switzerland,

⁴ Medical Metrics, Houston, United States,

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

Introduction: Despite the reported high fusion rates in patients treated with ACDF, there remains a lack of consensus on how best to define non-union. Use of dynamic flexion-extension radiographs with inter-spinous process motion (ISPM) cutoff of 1mm has been widely used, but the ability to reproducibly measure with 1mm of accuracy is unclear. Recently, multiple new tools have come available to aid in this assessment, and range from stabilization and segmentation aids, all the way to completely automated artificial intelligence (AI) based assessments. The purpose of this study was to compare the fusion assessments made by expert spine surgeon reviewers against technician reviewers working with the aid of the AI assisted tools. Material and Methods: Three methods of fusion assessment were compared. In Method 1, three senior level clinician experts evaluated 19 levels of ACDF from 9 patients using flexion-extension radiographs. A combination of ISPM measurements as well as a global assessment of radiographic markers of non-union such as interbody subsidence, hardware displacement, and the presence of radiolucent lines in the disc space, were used. Any case in which all three reviewers did not agree was then further discussed by the entire panel and a consensus was determined. For both Methods 2 and 3, the fusion assessment was performed by a technician. In Method 2, a certified technician (> 5 months of training) measured ISPM with Quantitative Motion Analysis (QMA, Medical Metrics) technology, which has been used extensively in clinical trials. This process minimizes error due to inconsistent landmarks and non-uniform magnification between images. ISPM is calculated by QMA; > 1 mm of ISPM was classified as nonunion. In Method 3, a technician assessed fusion status using intervertebral motion (IVM) results from a fully automated AI (SpineCAMP, Medical Metrics) in line with the protocol by Hipp et al¹: IVM < 1 deg rotation & < 5% strain = fused; IVM > 2 deg rotation & > 8% strain = pseudoarthrosis. The final diagnosis for all three methods were obtained in a blinded manner. Results: There was uniform agreement across the three methods in 17/19 (89.5%) samples. There were two cases in which Method 1 resulted in an Indeterminate assessment. In one of these cases Method 2 and Method 3 disagreed (Fused and Nonunion respectively). In the other disagreement case, Method 2 and Method 3 agreed (Fused). Agreement was 100% across all 3 cases when the expert clinician consensus (Method 1) was not Indeterminate. Conclusion: The accurate assessment of fusion status is important with respect to post-operative monitoring and long-term follow-up of symptomatic patients as well as for comparing outcomes of new implant designs and osteobiologics across studies. This comparative study demonstrates how technology enables non-clinicians to assess fusion outcomes with near identical results to those produced by an expert clinician panel. AI assisted fusion assessment technologies should be further investigated, and may provide a tool for standardizing fusion assessments across research studies, as well as for helping non-expert clinicians provide equivalent results to those from an expert panel.

ID: 356

A202: Anterior ultrasound imaging of the lumbar spine: a prospective cohort study defining normal parameters

Cody Schlaff ¹ , Christopher Knaus ² , Ayden Harris ² , Heather Decot ^1,3 , Sennay Ghenbot ¹ , Donald Fredericks, Jr. ¹ , Alfred Pisano ¹ , Melvin Helgeson ⁴ , Scott Wagner ¹

¹ Walter Reed National Military Medical Center, Orthopaedics, Bethesda, United States,

² Walter Reed National Military Medical Center, Radiology, Bethesda, United States,

³ Geneva Foundation, Bethesda, United States,

⁴ Mayo Clinic, Orthopaedics, Rochester, United States

Introduction: The United States and Coalition Forces have experienced a plethora of battlefield injuries over almost two decades of active conflict with spine fractures being the second most common missed injury. With recent use of ultrasound on the International Space Station (ISS) to provide images of the spine (Marshburn et al. 2014), this imaging modality seems ideal for expanded use for spinal imaging in an austere/low resource environment to aid in the battlefield triage of injured service-members. The primary aim of this study is to apply the ultrasound protocol developed by Marshburn et al., to obtain diagnostic quality images of the lumbar spine in active-duty service members to define normal physiologic parameters. Material and Methods: Twenty-eight active-duty healthy servicemembers were prospectively enrolled and underwent an anterior lumbar ultrasound from L1-S1 as described by Marshburn et al. 2014. Images collected were independently analyzed by three readers for anterior vertebral body height (VBH), intervertebral disc height (IDH) and width (IDW), space available for the central canal (SAC), neuroforaminal diameter (NFD) and sacral slope (SS) were compared to historical published controls. Data analysis included Welch’s t-test and Bland-Altman analysis for agreement. Results: The average morphometric measurements on the lumbar spine were: VBH 31 ± 3.7 mm, IDH 9.1± 2.4 mm and decreased through the upper lumbar segments, IDW 39.4 ± 5.3 mm, SAC 10.4 ± 2.4 mm, NFD 4.6 ± 1.8 mm, and SS was 35.6 ± 9.0°. Average SS was within 1 standard deviation of historical controls. Average disc height/width and SAC were also within 1 standard deviation. Mean neuroforaminal diameter was more difficult to visualize and was greater than 2 standard deviations from historical controls. Bland-Altman analysis demonstrated good agreement between reviewers and between ultrasound and matched MRI for all lumbar parameters. All parameters demonstrated minimal systematic bias and fell within the levels of agreement. Conclusion: With the nature of future conflicts likely to be further away from definitive medical care with advanced imaging capabilities and lack of advanced imaging in developing nations, successful creation and implementation of spinal ultrasound imaging will provide a familiar diagnostic tool to aid forward deployed providers. The normal values described here will serve as a reference for identifying lumbar spine pathology. We show that quality images can be reproducibly obtained in a short duration with ultrasound provided near similar measurements compared to historical CT controls. Additionally, Bland-Altman analysis demonstrated good agreement to matched MRIs in all parameters and between reviewers with all measurements falling within the limits of agreement and with minimal bias or heteroscedasticity. Future work should focus on real-time assessment of known spinal trauma and future development of more powerful hand-held base ultrasounds to increase resolution.

ID: 941

A203: Does repeat MRI in 90 days in spine infection patients lead to a change in care: a single institution study

Erin Choi ¹ , Joseph Rund ¹ , Natalie Glass ¹ , Yumeng Gao ¹ , Catherine Olinger ¹

¹ University of Iowa, Iowa City, United States

Background: Unnecessary magnetic resonance imaging (MRI) can lead to increased cost, inappropriate treatment, and patient anxiety. The incidence of inappropriate MRI can be upwards of 59%. The Infectious Disease Society of America (IDSA) clinical practice guidelines for vertebral osteomyelitis recommend using Erythrocyte sedimentation rate (ESR) and/or C-reactive protein (CRP) and clinical assessment to monitor vertebral osteomyelitis. The IDSA recommends against routinely ordering follow-up MRIs in patients with favorable clinical and laboratory responses. This study aims to investigate if repeat MRI within 90 days of the initial MRI for patients with spine infection leads to a change in patient care. Methods: All patients with at least two spine MRIs (repeated MRI) at a single institution between January 1, 2019- December 31, 2023, were reviewed. Inclusion criteria were infectious pathology and age > 18. Outcomes measured included demographics, surgical intervention, change in physical exam, administration of fast-acting anti-anxiety medication and ordering physician specialty. An estimated cost analysis was also performed. Results: 222 repeat MRIs in 141 patients were included in the final cohort after inclusion criteria were applied. 163 repeat MRIs were performed < 90 days from the first MRI and 59 repeat MRIs were performed > 90 days and served as the control group. Demographic data showed that the patients who had repeat MRIs > 90 days were significantly younger (p = 0.03). Otherwise, there was no difference in sex, BMI, race, ethnicity, or smoking status between the two cohorts. Patients who had a repeat MRI > 90 days were significantly more likely to have surgical intervention (p = 0.04) and a change in their physical exam (p > 0.001). Patients who had a repeat MRI < 90 days were significantly more likely to be administered an anti-anxiety medication prior to MRI (p = 0.04). Anti-anxiety medication was required prior to MRI for 30% of all patients. Infectious disease, neurosurgery, and internal medicine were the top three specialties with physicians who ordered repeat MRIs, accounting for 76.2% of all repeat MRIs identified. An estimated cost-analysis of repeated MRIs was $1,995,375 during this timeframe. Conclusion: Acquiring repeat MRIs within 90 days of the initial MRI does not lead to a change in patient care. Repeat MRIs were both expensive and led to anxiety in 30% of patients. Inflammatory labs are more cost-efficient and should be used to monitor patients with spine infections.

ID: 2198

A204: Curve magnitude and vertebral rotation influences the MRI predictability of pedicle dimensions in adolescent idiopathic scoliosis - an analysis of 1860 pedicles

S. Rajasekaran ¹ , Karthik Ramachandran ¹ , Ashish Naik ¹ , Ajoy P. Shetty ¹ , Rishi Kanna ¹

¹ Ganga Hospital, Department of Spine Surgery, Coimbatore, India

Introduction: The measurement of pedicle dimensions using MRI in AIS patients with structural thoracic curves has been studied, and its reliability has been proven. Large structural curves in AIS are characterised by increased vertebral rotation at the apex and periapical region, which are associated with a greater degree of pedicle dysmorphism. So far, the MRI predictability of pedicle dimensions based on the severity of the curve magnitude, and degree of vertebral rotations has not been studied. The purpose of the study is to determine and compare the MRI predictability of pedicle dimensions based on the severity of the curve, magnitude, and degree of vertebral rotation. Material and Methods: Operated AIS patients with pMRI and iCT scan images were included. Patients were categorised based on structural curve magnitude into Group 1 (50-70^o), Group 2 (71-90^o), and Group 3 (> 90^o). The degree of vertebral rotation was measured by the Nash and Moe method. Bilateral T2–L4 vertebral levels were evaluated for pedicle chord length and pedicle isthmic diameter to determine the correlation between pMRI and iCT. Results: A total of 1860 pedicles in 62 patients were analysed. We had 31 patients in Group 1, 22 in Group 2, and 9 patients in Group 3. Comparison between pMRI and iCT for the pedicle diameter showed good to excellent reliability (ICC = 0.87, 95% CI = 0.75-0.99) at all levels except the apical levels across three groups. At the apical levels, the comparison showed good correlation (ICC = 0.87, 95% CI = 0.85-0.89) in Group 1, moderate correlation (ICC = 0.75, 95% CI = 0.62-0.89) in Group 2, and poor reliability (ICC = 0.37, 95% CI = 0.27-0.47) in Group 3. The pedicle length showed good to excellent reliability (ICC = 0.92, 95% CI = 0.85-0.99) across all three groups. Comparison showed that Nash and Moe grade N and 1+ for pedicle diameter showed excellent correlation (ICC = 0.95, 95% CI = 0.90-0.99), whereas grade 2+ showed good correlation (ICC = 0.84, 95% CI = 0.74-0.94) at all levels. Grades 3+ and 4+ showed moderate to good correlation (ICC = 0.77, 95% CI = 0.56-0.99) at all levels except at the apex. At the apical level, grade 3+ showed poor to moderate correlation (ICC = 0.50, 95% CI = 0.25-0.75), and grade 4+ showed poor correlation (ICC = 0.44, 95% CI = 0.21-0.68). The pedicle length showed good to excellent reliability across all groups. Conclusion: The degree of vertebral rotation and the magnitude of the structural curve both have a significant impact on the MRI prediction of the pedicle dimensions, with a decrease in predictability as the curve magnitude and vertebral rotation increases.

ID: 2062

A205: The importance of the psoas muscle on low back pain: a single-center study on lumbar spine magnetic resonance imaging

Fabrizio Russo ¹ , Gianluca Vadalà ¹ , Giuseppe Francesco Papalia ¹ , Luca Ambrosio ¹ , Carlo Mallio ¹ , Rocco Papalia ¹ , Vincenzo Denaro ¹

¹ Campus Bio-Medico University Hospital Foundation, Rome, Italy

Introduction: Low back pain (LBP) prompts numerous magnetic resonance imaging (MRI) examinations of the lumbosacral spine. The specific role of soft tissues, particularly muscles, in LBP remains unclear, and detailed exploration of each MRI-derived parameter's contribution to LBP intensity is lacking. This study seeks to examine the relationship between soft tissue status, as derived from MRI parameters, and LBP. The focus is on evaluating the individual impact of parameters such as the area of paravertebral and psoas muscles, extent of intramuscular fat infiltration, and disc degeneration from L1 to S1 on LBP. Material and Methods: This retrospective observational study, conducted at a University Hospital, involved 94 patients experiencing LBP due to degenerative disc disease who underwent MRI scans of the lumbosacral spine. Imaging was performed with a 1.5 Tesla scanner. Patients provided symptom information through a questionnaire and assessed their pain intensity using the Visual Analogue Scale (VAS). VAS scores were classified as mild, moderate, or severe, with cutoff values of 3.8 and 5.7 based on literature. Biometric data, encompassing weight and height, were recorded for calculating the body mass index (BMI). The ratios between intramuscular fat infiltration and net muscle area were computed. Results: The stepwise analysis revealed that increasing psoas net area was associated with lower VAS levels [odds ratio (OR): 0.94: 95% confidence interval (CI): 0.90-0.98; p = 0.005], and an increase of one square centimeter of total psoas area resulted in a greater probability of reporting a mild (+1.21%; 95% CI: 0.37, 2.05%) or a moderate VAS (+0.40%; 95 % CI: -0.02, 0.82%), Furthermore, a more severe VAS was associated with a higher BMI (OR: 1.13; 95% CI: 1.00-1.27). Conclusion: Our research reveals a connection between LBP and the status of paravertebral and psoas muscles as indicated by MRI parameters. The significance of the psoas muscle in spine stabilization is underscored, and its correlation with clinical symptoms in LBP patients is evident. These insights have the potential to inform future studies and enhance treatment strategies for individuals with LBP, with the prospect of mitigating the effects on disability, quality of life, and socio-economic burdens.

ID: 561

A206: Prospective cohort study investigating the impact of muscle degeneration on low back pain after lumbar decompression

Pedro Henrique Couri ¹ , Alberto Gotfryd ¹ , Mario Lenza ¹ , Eliane Antonioli ¹ , Adham Castro ²

¹ Hospital Israelita Albert Einstein, Orthopaedics, São Paulo, Brazil, ² Hospital Israelita Albert Einstein, Radiology, São Paulo, Brazil

Introduction: The main reason for surgical procedures in the lumbar spine is nerve compression associated with radiculopathy or neurogenic claudication. Lumbar surgical decompression is effective in relieving neurogenic pain and restoring walking ability. However, the presence of associated preoperative low back pain (LBP) in patients with neurological symptoms is not uncommon, and its management is still controversial. Chronic dysfunctions, such as atrophy and muscle fat replacement of the main spine muscles, are related to pain intensity. These dysfunctions can be identified and measured by means of magnetic resonance imaging (MRI) as muscle fat infiltration and reduction of muscular cross-sectional area. The primary objective of this study was to correlate the degree of muscle degeneration with the presence of LBP before lumbar decompression surgery. The secondary objectives are evaluations of the impact of different surgical techniques in muscle degeneration, as well as of the association of pain, disability, quality life and psychosocial factors during recovery after lumbar decompression surgery. Material and Methods: This prospective cohort will include individuals older than 18 years who underwent surgical lumbar decompression. Radiographic exams and MRI examinations will be performed before the surgical procedure. Inclusion criteria: • adults aged 18 years and older; • symptoms of lumbosacral neural compression (radiculopathy or neurogenic claudication); • failed conservative treatment for at least 6 weeks; • undergoing surgery for neural decompression (discectomy and/or foraminotomy and/or hemilaminectomy); • with preoperative MRI image. Exclusion criteria • need for lumbar fusion; • spondylolisthesis > Meyerding Grade I; • deep infection requiring surgical debridement; • patients submitted to lumbar facet rhizotomy; • active rheumatologic disease, including seronegative arthropathies; • reoperation. Low back pain will be assessed using the Visual Analog Scale at baseline and 6 months post-surgery. We will analyze a 1.5-point change in the pain scale (VAS) among patients with and without muscle degeneration. Radiological evaluations will be performed using MRI examinations to assess muscle degeneration and fat infiltration. Qualitative and quantitative analyses will be conducted, with measurements of muscle cross-sectional area and fat infiltration grades. Sociodemographic characteristics including age, sex, body mass index, formal education, and occupation will be recorded. Additionally, psychosocial factors such as fear of movement, catastrophizing, mood disorders, and self-perception in recovery will be assessed. Descriptive statistics will be used to summarize numerical and categorical variables. Linear models will be employed to assess the relation between low back pain scores and fat infiltration, surgical technique, and radiographic findings. Generalized mixed models will be adjusted to investigate variations in clinical assessment instrument scores over time. Results: We reported reductions in ODI score means in postsurgical estimates from baseline in patients with and without fat infiltration (p < 0.001 in all comparisons), and significant reductions in mean ODI scores at 3-, 6- and 12-months postoperative estimates from baseline in patients with and without fat infiltration (p < 0.05 in all comparisons). Conclusion: According to partial statistical reports, there is a suggestion that patients with less fat infiltration have less low back pain and less disability during serial postoperative evaluations, considering ODI scores.

ID: 924

A207: MRI-based synthetic CT in pediatric spine patients: a case series

George Michael ¹ , Suhas Etigunta ¹ , Andy Liu ¹ , David Skaggs ¹ , Meliza Perales ¹ , Cristabelle Alexander ¹ , Christopher Watterson ² , Daniel Hoghoughi ² , Norman Gellada ² , Kenneth Illingworth ¹

¹ Cedars-Sinai Medical Center, Pediatric Spine/Orthopaedics, Los Angeles, United States,

² Cedars-Sinai Medical Center, Imaging Center, Los Angeles, United States

Introduction: Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) are common imaging studies used to evaluate pediatric spine patients. Recently, MRI-based synthetic CT (sCT) images have demonstrated near equivalence in accuracy when compared to CT in cadaveric studies. This recent advancement allows potential visualization of both bony and soft tissue anatomy without harmful ionizing radiation. To date, there are no reports of the use of sCT in the evaluation of pediatric spinal pathologies. This study aimed to evaluate the clinical utility of MRI-Based sCT in the clinical management of pediatric and adolescent patients suffering from various spinal conditions. Methods: Retrospective chart review of pediatric spine patients seen at a clinic affiliated with a quaternary care hospital from October 2023- August 2024. The inclusion criteria were any patient seen and referred for spinal MRI with the addition of bone sequence and sCT. An experienced musculoskeletal or neuroradiologist read the images, and the attending pediatric spine surgeon discussed and confirmed the findings. Case reports were generated for each patient by chart review with IRB approval. Results: 20 patients underwent spinal MRI with the addition of sCT-generated sequences, two of which were done on the cervical spine and 18 on the lumbar spine. The two cervical patients were assessed for any cervical bony anomalies causing their congenital muscular torticollis, with both later undergoing bipolar sternocleidomastoid release. Eight of these patients had isolated spondylolysis, with L5 being the most affected vertebrae (n = 5). Of these eight patients, two had undergone surgical intervention for repair of the defect. Three of the patients were evaluated for their grade 1 spondylolisthesis and three had scoliosis of varying degrees with associated lower back pain concerning for posterior element fracture. MRI-generated sCT for three of the patients was utilized to possibly diagnose a cause of chronic (> 1 year). Three patients had transitional anatomy and vertebral anomalies, with two causing pseudo articulation at the lumbosacral junction. Five of the 20 patients had received thin-section CT scans within 3 months prior to MRI-based sCT imaging. Comparison of the thin-section CT and sCT demonstrated no discernable differences in image quality or potential for accurate diagnosis according to the senior author and pediatric musculoskeletal trained radiologist. Conclusion: MRI-generated sCT has significant clinical utility in the pediatric and adolescent population, allowing the diagnosis of both bony and soft tissue pathologies without exposing patients to radiation and utilizing a single imaging study. Although more widespread integration is necessary, the ability to use a single imaging study could promote less time for diagnosis and intervention. In conclusion, we feel that sCT is a groundbreaking tool for providers dealing with complex pediatric spinal pathologies.

OP24: Cervical Arthroplasty and Fusion

ID: 2305

A208: Cervical fusion versus arthroplasty in the United States commercially insured population

Thiago Scharth Montenegro ¹ , Katherine Corso ² , Katherine Locke ³ , Glenn Arthuro Gonzalez ⁴ , Kevin HinesTh ⁴ , Sara Thalheimer ⁴ , Caio Matias ⁴ , Mohamed Abouelleil ¹ , Philippe Scharth Montenegro ¹ , Aline De Quadros Teixeira ¹ , Lucca Palavani ⁵ , Ashwini Sharan ⁴ , Joshua Heller ⁴ , James Harrop ⁴

¹ Michigan State University, Grand Rapids, United States,

² Johnson & Johnson Medical Devices, New Brunswick, United States,

³ Drexel University College of Medicine, Philadelphia, United States,

⁴ Thomas Jefferson University, Philadelphia, United States,

⁵ Max Planck University Center, Sao Paulo, Brazil

Study Design: This is a retrospective cross-sectional study. Objective: This study aims to examine the overall trends of cervical fusion and arthroplasty over time among United States (U.S.) commercially insured enrollees. Summary of Background Data: The early 2000s brought a new surgical option to traditional spinal fusion techniques for the treatment of symptomatic cervical degenerative disc disease with the FDA approval of the artificial disc to the United States (U.S.) market. Material and Methods: A retrospective cross-sectional study of IBM MarketScan Commercial Claims and Encounters Database was utilized to identify patients 19-64 years of age with cervical disk arthroplasty (CDA) or cervical fusion (ACDF) between 2005 to 2018. Elective spine patients with 1-2 level treatment were included. Patient-level procedure counts were projected to the U.S. commercially insured population. Yearly incidence and percent of characteristics were estimated per procedure and the percent change was used to summarize changes over time. Logistic regression models were used to compare the characteristics of patients who underwent fusion versus arthroplasty. Results: From 2005 to 2018, the projected count and incidence of CDA increased, while ACDF declined. In 2018, the estimated incidence of procedures was 9.9 per 100,000 enrollees and 58.0 per 100,000 enrollees, CDA and ACDF, respectively. Compared to arthroplasty, ACDF patients were older, more comorbid, female, diagnosed with stenosis/myelopathy or spondylosis, but had less outpatient procedures and Degenerative disk disease without myelopathy. The percentage of patients with high comorbidity scores (> 2) and outpatient surgery increased over time for all procedures. Conclusion: This illustrates that over the past decade there has been continual growth in CDA among the commercial insured population demonstrating a trend in motion-preserving techniques.

Keywords: Cervical Fusion, Arthroplasty, Total Disc Replacement

ID: 1004

A209: Efficacy, safety and reliability of anterior cervical discectomy and fusion (ACDF) in sub axial cervical spine injury

Shah Alam¹, Md. Ziaul Hasan², Sarwar Jahan², Abdullah Al Mamun²

¹ Bangladesh Spine and Orthopedic Hospital, BSOH, Spine and Orthopedic Surgery, Dhaka, Bangladesh,

² National Institute of Traumatology and Orthopedic Rehabilitation, NITOR, Spine and Orthopedic Surgery, Dhaka, Bangladesh

Background: The optimal course of treatment for cervical spine Injury (CSI) is still up for debate, however anterior cervical surgery with direct decompression is starting to gain traction. It is uncommon to find, though, in the published literature, that a single anterior strategy can effectively manage every case with sub axial CSI. Methods: Study comprised patients with sub axial CSI who underwent surgical stabilization utilizing a single anterior approach by ACDF. Most of the CSI was reduced and anterior cervical discectomy and fusion (ACDF) were performed. The patient's neurological condition, radiological findings, and functional outcomes were assessed. Results: There were 164 operated cases in all, and the average follow-up period was 42 months. The average age was 10.92 ± 37.50 years. C5/C6 injuries were the most common (58.7%). In 92.9% of cases, a reduction was accomplished. An average of 102.62 ± 25.27 ml of blood was lost throughout the 74.25 ± 9.45 minute operation. With the exception of total spinal cord injury (CSI), all subjects showed neurological improvement (89.73%). After surgery, the preoperative mean visual analog score (VAS) was improved to 2.15 ± 0.98 (p < 0.05), and the mean Neck Disability Index (NDI) was 11.19 ± 11.43. Fusion was accomplished in each instance. Transient dysphagia was the most frequent side effect (13.4%). After the procedure, no patient had a deterioration in their neurological condition. With two exceptions, implant failure was not noted at the last follow-up. Conclusion: According to the study's findings, treating subaxial CSD with a single anterior approach is a safe, efficient method that produces positive neurological, functional, and radiological effects.

ID: 2717

A210: Eliciting surgeon preferences regarding anterior cervical discectomy fusion, cervical disc arthroplasty, and hybrid constructs: an international survey

Philip Louie ¹ , Patricia Lipson ^1,2 , Aiyush Bansal ¹ , S. Tim Yoon ³ , Amit Jain ⁴ , K. Daniel Riew ⁵

¹ Virginia Mason Medical Center, Seattle, United States,

² University of Washington, Seattle, United States,

³ Emory University, Atlanta, United States,

⁴ John Hopkins University, Baltimore, United States,

⁵ Weill Cornell University, New York City, United States

Introduction: Anterior cervical discectomy and fusion (ACDF) has long been the gold standard for treating degenerative cervical stenosis, but cervical disc arthroplasty (CDA) has rapidly increased over the past decade. Despite their potential, hybrid constructs (a combination of ACDF and an adjacent disc arthroplasty) are rarely performed. Therefore, the primary objective of this study is to understand and assess the factors influencing the choice of cervical fusion, disc arthroplasty, and hybrid procedures. Methods: A multi-dimensional survey was distributed to surgeons worldwide as part of the AO Spine membership. Questions were focused on surgical preferences, challenges, and barriers with various anterior cervical techniques. Results: A total of 267 surgeons participated in this survey, representing 5 regions across the globe. The majority of participants practice in Europe and Southern Africa (31.5%) followed by Asia Pacific (27.3%), North America (16.5%), Latin America (15.7%), and Middle East and Northern Africa (8.9%). Participants were either trained in orthopedics (61.1%) or neurosurgery (38.6%). Experience varied with 25.5% of respondents having greater than 20 years of experience following residency and/or fellowship. Of the 92.9% of respondents who perform cervical spinal surgery, 99.6% perform cervical fusions, 58.9% perform cervical arthroplasty, and 39.9% perform hybrid surgery. In terms of comfortability level, 66.7% of respondents stated being experts at two-level ACDF, while only 42.1% and 35.4% regard themselves as experts in two-level CDA and hybrid surgery (ACDF at one level and CDA at adjacent level), respectively. Respondents cited the potential for CDA to preserve motion at the index level (71.7%) and CDA having less deleterious effects at adjacent disc levels (71.7%) as the two most common advantages of a hybrid construct compared to a 2-level ACDF. Additionally, respondents were asked where they believe the more advantageous location of a CDA in relation to a fusion is in a hybrid construct; the majority of respondents said it depends on the clinical scenario or CDA above the ACDF. Conclusion: Cervical fusions remain far more commonly performed globally, compared to cervical disc arthroplasty. Despite their potential advantages in preserving motion and reducing adjacent segment degeneration, hybrid procedures are less frequently performed, with fewer surgeons considering themselves experts in this technique. There appears to be some interest in the ability to combine the two techniques to perform a hybrid construct. However, tremendous clinical equipoise exists amongst clinical scenarios. Future studies should provide further insight to the indications for a hybrid construct based on short and longer term outcomes.

ID: 2786

A211: Visualized and bibliometric analysis of 100 most cited articles on cervical spondylotic myelopathy

André Nishizima ¹ , Rafael Silva ¹ , Luciano Carneiro Filho ¹ , Kenzo Donato ¹ , Danilo Gomes Quadros ²

¹ Bahiana School of Medicine and Public Health, Salvador, Brazil,

² Núcleo Oscar Freire, Salvador, Brazil

Introduction: Cervical Spondylotic Myelopathy (CSM) is recognized as the most prevalent cause of spinal cord dysfunction. This condition arises due to degenerative changes in the cervical spine, leading to compression of the spinal cord and subsequent neurological deficits. Research on CSM has evolved substantially, influencing clinical practices and surgical techniques. This study aims to perform a bibliometric analysis of the 100 most cited articles related to CSM, highlighting key trends and influential contributions to the field. Material and Methods: A search was conducted in the Web of Science database to identify the 100 most cited papers on CSM. Data were extracted regarding publication year, authors, country of origin, journal, and total citations. Citation trends, co-authorship networks, and keyword co-occurrence were visualized using VOSviewer software and the R package “bibliometrix”. Results: A total of 2804 eligible papers were retrieved. The timespan varied from 1957 to 2019, with 2013 being the most active year. The 100 most cited papers were published in 27 different sources, and “Spine” is the one with the most number of documents, followed by “Journal of Neurosurgery” and “Neurosurgery”. The top 100 most-cited articles ranged from 133 to 700, the average number of citations per document was 215.8, and the most cited sources were Spine, Journal of Neurosurgery and Brain. Spine emerged as the journal with the highest number of publications, while studies focused predominantly on surgical approaches. The United States is the leading citation country, followed by Japan and Canada. Most of the articles were affiliated with the University of Toronto, followed by Osaka University and Toronto Western Hospital. The most cited authors are Yonenobu K, Ono K, and Fehlings MG. The main keywords were “spondylotic myelopathy”, “cervical spondylotic myelopathy”, “laminoplasty”, “surgical treatment”, “laminectomy”, “laminoplasty” and “corpectomy”. Conclusion: This bibliometric analysis offers an overview of the most influential studies on CSM, with the United States leading both in quantity and impact. The focus on surgical interventions underscores the importance of these procedures in CSM management. These insights into citation patterns and collaboration networks provide a foundation for research and academic exploration in the treatment of CSM.

ID: 1790

A212: Relative prosthesis mobility of single-stage multi-level cervical disc arthroplasty

Alex Quok An Teo ¹ , Spencer Loh ¹ , Shiting Chiu ¹ , Jacqueline Yang ¹ , Dennis Hey Hwee Weng ¹

¹ National University Hospital Singapore, National University Spine Institute, Department of Orthopaedic Surgery, Singapore, Singapore

Introduction: Cervical disc arthroplasty is rapidly gaining popularity as a choice of surgery for an ever-expanding list of indications. Initial US FDA approval for disc arthroplasty limited surgeons to two levels of arthroplasty in one sitting. There is however a growing body of evidence demonstrating the safety of multiple level cervical arthroplasty if indicated. A larger number of disc replacements invariably introduces larger increases in overall spinal column length and therefore stretches the surrounding soft tissues post-operatively, which may limit the overall mobility of the implants. This study was performed to compare the regional and global range of motion in patients undergoing three or four-level cervical disc replacement compared to those undergoing one or two. Material and Methods: 88 consecutive patients who underwent 183 levels of cervical disc arthroplasty for cervical myelopathy or cervical radiculopathy were retrospectively analysed. All patients were operated on by a single fellowship-trained spine surgeon based in an academic spine surgery tertiary referral center. The same implant was used for all patients. All patients had radiographs of their cervical spine taken in neutral, flexion and extension views, performed pre- and immediately post-operatively, as well as at 3 months and 1 year post-operatively. Radiographic indices measured include cervical lordosis (CL), global cervical spine range of motion (from flexion to extension) as well as segmental lordosis/kyphosis and overall ROM at the operative levels. Note was also made of any need for revision surgery for any reason related to the index surgery. The cohort was divided into two cohorts, cohort one included those undergoing one or two-level arthroplasty and cohort two included those undergoing three or four-level arthroplasty. Level of significance for statistical analyses was set to p < 0.05. Results: 60 patients underwent one or two-level disc arthroplasty, while 28 patients underwent three or four-level disc arthroplasty. Within the first cohort, 27 patients underwent single-level arthroplasty, most commonly at C5/6. Within the second cohort, 5 patients underwent 4 level arthroplasty from C3/4 to C6/7. Both cohorts were equivalent at baseline in terms of pre-operative CL (0 vs 4.3 degrees, p = 0.1762), operative level segmental lordosis (0.9 vs 3.1 degrees, p = 0.242) and pre-operative range of motion (38.2 vs 31.6 degrees, p = 0.128). Range of motion of the operative levels was not significantly different from 3 months to 1 year (p = 0.911). Cohort one had a post-operative mean range of motion per disc of 11.2 degrees, which was significantly more than cohort two (7.4 degrees, p = 0.0016) at 1 year post-operatively. No patients required revision surgery within the 1 year follow up period. Conclusion: Performing single-stage multiple level cervical disc arthroplasty is feasible and safe, however may lead to slightly decreased mobility of the prostheses at each level compared to performing one or two levels.

ID: 2707

A213: Investigating the influence of locus of control on post-operative spinal surgery outcomes

Amanda Faust ¹ , Michaela Thomson ¹ , Angela Atkinson Atkinson ¹ , Don Moore ¹

¹ University of Missouri, Columbia, United States

Introduction: A variety of factors including pain chronicity, comorbidities, psychological distress, and social support influence postoperative outcomes after spine surgery. One novel factor that may contribute to patient outcomes is locus of control. Locus of control is a concept derived from social learning personality theory. Social learning theory is grounded in reinforcement values and social context as they relate to personality development. Locus of controls can be described by three domains; internal, external (others), and chance. The extent to which an individual believes these domains influence their life defines their personal locus of control. Patients' locus of control can be a combination of these domains to varying degrees. In chronic illness research, an additional domain has been identified and coined as “doctors”. This describes the extent to which patient’s believe their doctor influence their condition. The natural history of spinal pathologies frequently involves chronic pain. Locus of control assessments could become a mainstay for this population to potentially help predict postoperative improvement and inform personalized patient education. Investigating the interaction between locus of control and postoperative outcomes is appropriate and potentially impactful for spine surgery patients. The aim of this study is to evaluate whether patients' locus of control influences post-operative outcomes spinal surgery patients. Material and Methods: This study is a retrospective study including patients treated with the following operations between 2019-2022; 1 level or more anterior or posterior cervical/lumbar fusions, 1 level or more cervical/lumbar laminectomy, and 1 level or more cervical corpectomy. We identified 119 patients via CPT codes. After identification each patient was contacted by phone to fill out a validated locus of control survey and NDI/ODI questionnaires. Results: Health locus of control overall significantly influenced NDI/ODI scores to a large effect. Univariate ANOVA demonstrated that internal locus and the doctor locus have significant effects on NDI/ODI scores. The internal locus had a significant effect on NDI/ODI scores (p = 0.00) with a large effect size (F(1, 117) = 18.7, p = 0.00, η²_p = 0.14). The doctor locus had a significant effect on NDI/ODI with a medium effect size (F(1, 117) = 15.6, p = 0.00, η²_p = 0.12). The chance locus and others locus did not demonstrate a significant effect on NDI/ODI scores (p = 0.35 and 0.05 respectively). Conclusion: Overall, our study demonstrates that for those whose domains are internal, doctor, or a mix of the two may experience different therapeutic effects after undergoing spinal surgery compared to those with the locus of others and chance. While we cannot draw conclusions on the extent to which having the internal and doctor domain impact the patient experience, we can say with confidence that psychosocial attributes have the power to influence post-operative outcomes to a great degree after spinal surgery.

ID: 1933

A214: Does pre-operative sagittal alignment influence the radiological outcomes of cervical artificial disc replacement?

Alex Quok An Teo ¹ , Spencer Loh ¹ , Jacqueline Yang ¹ , Shiting Chiu ¹ , Dennis Hey Hwee Weng ¹

¹ National University Hospital Singapore, National University Spine Institute, Department of Orthopaedic Surgery, Singapore, Singapore

Introduction: Cervical artificial disc replacement (ADR) is increasingly performed worldwide, with purported benefits of motion-preservation and minimization of adjacent segment degeneration. There has been some concern about performing ADR in kyphotic segments, for fear of worsening the kyphotic deformity. This study aims to compare the radiographic outcomes following ADR in patients with kyphotic, neutral and lordotic cervical spines. Material and Methods: The medical records and radiographs of 88 consecutive patients who underwent 1 to 4 levels of cervical disc arthroplasty for cervical myelopathy or cervical radiculopathy were retrospectively analysed. All patients were operated on by a single fellowship-trained spine surgeon based in an academic spine surgery tertiary referral center. The same implant was used for all patients. All patients had radiographs of their cervical spine taken in neutral, flexion and extension views, as well as full body slot scanning imaging pre-operatively, and at 3 months and 1 year postoperatively. Radiographic indices measured include cervical lordosis (CL), global cervical spine range of motion (ROM) as well as segmental lordosis and overall ROM at the operative levels. Regional and global sagittal balance parameters were also measured. Patients were divided into 3 cohorts ‒ kyphotic, neutral and lordotic ‒ according to their pre-operative CL on a neutral lateral radiograph. Level of significance was set to p < 0.05. Results: There were 35, 29 and 24 patients in the kyphotic, neutral and lordotic cohorts respectively. The mean global CL in the 3 cohorts was significantly different in neutral (13.5 vs 1.0 vs -13.9, p < 0.00001), flexion and extension views on the pre-operative radiographs. The mean segmental lordosis at the operative levels in the 3 cohorts was also different (7.2 vs 1.2 vs -5.5, p < 0.00001). The mean range of motion at baseline was similar across all cohorts, both overall (p = 0.161) and segmentally (p = 0.582) at the operative levels. There was a higher mean number of levels operated on in the kyphotic compared to the lordotic cohort (2.5 vs 1.7, p = 0.00084). CL and segmental lordosis was maintained in the lordotic group and increased in the neutral (1 vs -4.2 degrees, p = 0.0272) and kyphotic (13.5 vs 7.4 degrees, p = 0.011) groups postoperatively. Global and segmental ROM was maintained in all 3 cohorts post-operatively. ROM per prosthesis however was lower in the kyphotic group (7.9 degrees) compared to the other 2 cohorts (lordotic 12.7 degrees, neutral 13.7 degrees, p = 0.0198). C2-7 SVA, and global sagittal balance parameters were unchanged post-operatively in all 3 cohorts. Conclusion: ADR can be performed safely in kyphotic cervical spine segments, and can be expected to produce a lordosing effect. Kyphotic cervical spines tended to be stiffer overall, with improvements in ROM seen following ADR albeit to a lesser extent per segment compared to lordotic and neutral spines.

ID: 2205

A215: Hybrid cervical spine surgery vs. standard surgery: comparison of clinical outcomes

Carlos Betancourt Quiroz ¹ , Eduardo Callejas ¹ , Jose Carlos Sauri Barraza ¹

¹ Centro Médico ABC Santa Fe, Cirugía de Columna Vertebral, Mexico City

Introduction: Cervical degenerative disc disease (CDD) is a prevalent condition that affects approximately 5% of the adult population, causing significant pain and disability. Traditional treatments include anterior cervical discectomy and fusion (ACDF), which, while effective in pain relief and stabilization, may increase the risk of adjacent segment disease (ASD). Cervical disc arthroplasty (CDA) emerged to preserve motion and potentially reduce ASD risk. However, neither technique alone fully addresses the complexity of multilevel CDD. Hybrid surgery (HS), which combines both fusion and motion preservation techniques, has been proposed as an alternative to overcome these limitations. This study aims to compare the clinical outcomes of hybrid cervical spine surgery with standard techniques (ACDF and CDA) for treating multilevel CDD. Material and Methods: A retrospective cohort study was conducted at Centro Médico ABC, Santa Fe, from January 2016 to June 2024. Patients diagnosed with multilevel cervical degenerative disc disease who underwent anterior microscopic approaches (either HS, ACDF, or CDA) were included. Clinical outcomes were measured using the Visual Analog Scale (VAS) for cervical and arm pain, and the Neck Disability Index (NDI). These were recorded preoperatively and at 1, 3, 6 months, and 1 year postoperatively. The study excluded patients with prior cervical surgeries or conditions such as cancer or rotator cuff disease. Statistical analyses were performed using IBM SPSS v27.0, with p-values < 0.05 considered statistically significant. Results: Seventy-seven patients were analyzed, with a median age of 56 years and a mean BMI of 24.02 kg/m². Significant reductions in cervical and arm VAS scores were observed across all groups, with a decrease from 4.28 to 2.82 for cervical VAS at 1 year (p < 0.001). Similar trends were observed in right and left arm pain VAS scores (p < 0.001). The NDI also improved significantly from 4.54 to 2.32 at 1 year (p < 0.001). While no significant differences were found between HS and ACDF/CDA at 1 year, HS demonstrated a trend toward better outcomes in terms of NDI reduction at 6 months (p = 0.035). Additionally, HS showed favorable results in arm pain relief, particularly in left arm VAS at 6 months (p = 0.007). Conclusion: Hybrid cervical spine surgery provides clinical outcomes comparable to standard techniques, with significant reductions in pain and disability over the first postoperative year. HS offers potential advantages in terms of motion preservation and may reduce the risk of adjacent segment disease. These findings suggest that HS is a viable and effective option for treating multilevel cervical degenerative disc disease, though longer follow-up is necessary to confirm its long-term benefits.

ID: 774

A216: Cervical laminoplasty is associated with lower healthcare costs as compared to cervical fusion procedures: a systematic review and meta analysis of comparative studies

Anthony Baumann ¹ , Omkar Anaspure ² , Shiv Patel ² , Nazanin Kermanshahi ³ , R. Garrett Yoder ⁴ , Keegan Conry ⁴ , Gordon Preston ⁴ , Jacob Hoffman ⁴

¹ College of Medicine, Northeast Ohio Medical University, Rootstown, United States,

² Perelman School of Medicine, Philadelphia, United States,

³ College of Medicine, Midwestern University, Glendale, United States,

⁴ Cleveland Clinic Akron General, Orthopedic Surgery, Cleveland, United States

Introduction: Cervical laminoplasty (CLP) and cervical fusion (CF) are viable alternatives for surgical management of cervical spine myelopathy, with no clear consensus on clinical superiority. However, there is limited data on the relative costs between CLP and CF despite clinical equivalence in patient outcomes. The purpose of this study is to examine the cost of CLP versus CF stratified by approach to guide decision-making. Methods: This systematic review and meta-analysis searched PubMed, CINAHL, MEDLINE, and Web of Science from database inception until January 17^th, 2024. Inclusion criteria were articles that examined cost between CLP and any type of CF (stratified by anterior, posterior, or combined approach). Article quality was determined by the Methodological Index for Non-Randomized Studies (MINORS) scale. A random-effects continuous model for meta-analysis was performed using standardized mean difference (SMD) due to heterogeneity in reported costs with frequency weighted mean (FWM) being used to describe cost. Results: Eleven retrospective articles out of 138 articles initially retrieved were included and determined to be low (n = 2 articles) or moderate quality (n = 9 articles). Patients (n = 21,033) had an average age of 56.0 ± 3.6 years and underwent either CLP (n = 4,364), posterior CF (n = 3,529), anterior CF (n = 13,084), or combined CF (n = 56). There was a statistically significant lower mean reported cost among patients who underwent CLP (n = 3,742) as compared to patients who underwent CF (n = 6,329), irrespective of approach for CF (FWM: $23,575.47 versus $33,699.57; p = 0.028; SMD = -2.965). For subgroup analysis by surgical approach, there was a statistically significant lower mean reported cost among patients treated with CLP as compared to patients treated with posterior CF (FWM: $18,060.64 versus $34,332.70; p = 0.013; SMD = -1.861) and anterior CF (FWM: $24,886.55 versus $33,567.95; p < 0.001; SMD = -0.344), but not combined approach (FWM: $2,791.78 versus $5,835.58 p = 0.063; SMD = -8.210) possibly due to a small sample size. Patients who underwent CLP had a statistically significant lower mean hardware cost as compared to patients who underwent posterior CF ($1,458.52 versus $7,204.59; p < 0.001; SMD = -3.275). Conclusion: CLP appears to be associated with statistically significant and clinically relevant lower reported costs as compared to CF, irrespective of approach based on meta-analysis of low or moderate quality retrospective studies. CLP may also have lower reported costs as compared to both posterior CF and anterior CF, although more data is needed for comparison between CLP and combined approach CF due to low power.

OP25: Basic Science 2

ID: 1261

A217: Structural changes of muscle spindles in the multifidus muscle after intervertebral disk injury are resolved by targeted activation of the muscle

Paul Hodges ¹ , Ben Ahern ² , Ben Goss ³ , Greg James ¹

¹ The University of Queensland, Centre for Innovation in Pain and Health Research (CIPHeR), Brisbane, Australia,

² The University of Queensland, School of Veterinary Science, Brisbane, Australia,

³ Mainstay Medical, San Diego, United States

Introduction: Low back pain is associated with impaired proprioception. This is likely to contribute to suboptimal motor control of the spine, and potentially, pain persistence. Animal data show that intervertebral disk (IVD) injury induces structural changes in the muscle spindles of the deep back muscles (multifidus), which provide critical sensory information regarding spine movement. These structural changes involve increased thickness of connective tissue of the capsule surrounding the spindles, and greater presence of collagen 1 (Col-I). This could underpin impaired proprioception. Fibrosis also accumulates throughout the multifidus. Other work has shown that targeted multifidus muscle activation (by restorative neurostimulation) in animals reduces muscle fibrosis. This antifibrotic effect might also reduce muscle spindle changes. We hypothesized that targeted multifidus activation in a model of IVD degeneration would attenuate the increased muscle spindle capsule thickness and reduce Col-I presence. Material and Methods: IVD degeneration was surgically induced in 18 merino sheep via a partial thickness unilateral annulus fibrosus lesion to the right side of the L1/2 and L3/4 IVDs. All 18 sheep received an implantable restorative neurostimulation device, that provides stimulation of the L2 medial branch of the dorsal ramus. Three months after surgery, animals were divided into two separate groups, Non-Activated and Activated. The Activated animals received two 30-minute neurostimulation sessions per day for 3 months. The non-activated group received no stimulation. Six months after surgery, the multifidus muscle was harvested adjacent to the spinous process adjacent to L2 (non-stimulated muscle) and L4 (stimulated muscle). Van Gieson’s stain examined the connective tissue of the muscle spindle capsule. Presence of Col-I was assessed using immunofluorescence assays. An AxioScan Z1 Scanner (Zeiss) and ImageJ (NIH) were used for slide imaging and data analysis, respectively. The whole CSA of the multifidus was imaged and each spindle was identified and imaged at an increased magnification for both the Van Gieson’s and immunofluorescence assays. Muscle spindle location was recorded based on their location along the mediolateral axis of the multifidus. Capsule thickness was measured at 8 points around the circumference of the spindle and averaged. Presence of Col-I in the connective tissue capsule was determined relative to surrounding background. Results: The thickness of the spindle capsule was significantly less in the neurostimulation than the injury group across the entire multifidus at L4 (p < 0.05). Regional analysis revealed that spindle capsule thickness was reduced in the neurostimulation and lateral spindle, when compared to the injury and medial spindles, respectively. Spindle capsule thickness was unchanged at L2. Col-I in the spindle capsule was significantly less in the neurostimulation group than the injury group across the multifidus at L4, but not L2. Conclusion: The results of this study suggest that targeted multifidus activation reverses fibrosis of the capsule of the multifidus muscle spindles that occur after IVD injury. Although requiring confirmation, if fibrosis of the muscle spindle capsule contributes to poor proprioception in back pain, these data suggest targeted activation of the multifidus muscle might provide an effective solution to resolve this deficit.

ID: 1187

A218: Promoting intervertebral disc fusion: the prostaglandin E2 receptor 4 agonist KMN159 acts synergistically with BMP2 and L51P to induce osteogenic differentiation of human annulus fibrosus cells

Shuimu Chen ^1,2,3 , Tian Xinggui ^4,5 , Stefan Zwingenberger ^4,5 , Christoph Albers ² , Benjamin Gantenbein ^1,2 , Sonja Häckel ^2,6

¹ University of Bern, Department for BioMedical Research (DBMR), Tissue Engineering for Orthopaedics & Mechanobiology, Bone & Joint Program, Bern, Switzerland,

² Inselspital, Bern University Hospital, Department of Orthopaedic Surgery and Traumatology, Bern, Switzerland,

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

⁴ University Hospital Carl Gustav Carus at TU Dresden, Center for Translational Bone, Joint and Soft Tissue Research, Dresden, Germany,

⁵ University Hospital Carl Gustav Carus at TU Dresden, University Center of Orthopedic, Trauma and Plastic Surgery, Dresden, Germany,

⁶ University of Bern, Graduate School for Health Sciences, Bern, Switzerland

Introduction: Spinal fusion surgery is often performed to restore proper spinal alignment, but it presents notable challenges, particularly in older patients with comorbidities. This study aims to identify factors that promote the fusion of intervertebral discs, focusing on minimally invasive approaches for spinal surgery. Specifically, we examine a novel method to induce osteogenic differentiation in annulus fibrosus cells (AFCs), using a combination of bone morphogenetic protein-2 (BMP2), L51P (a BMP2 analog), and KMN159 (a prostaglandin E2 receptor 4 agonist, which modulates inflammatory processes). Material and Methods: Primary human AFCs (n = 4) were stimulated with BMP2, L51P, and KMN159 and cultured for 21 days. Cell viability was assessed to detect cytotoxic effects following stimulation. At 7, 14, and 21 days, osteogenesis was evaluated by measuring the transcription levels of bone-related genes: alkaline phosphatase (ALP), Runt-related transcription factor 2 (RUNX2), bone gamma-carboxyglutamate protein (BGLAP, also known as osteocalcin), secreted phosphoprotein 1 (SPP1, also known as osteopontin), osterix (SP7), and type I collagen (COL1). In parallel, BMP antagonists such as Noggin, Gremlin 1, and Chordin were quantified using quantitative polymerase chain reaction (qPCR). On Day 14, ALP activity was measured at the protein level, and on Day 21, histological staining with alizarin red (ALZR) was performed to detect calcium deposits, indicating mineralization. Results: KMN159 had no discernible impact on the cell viability of AFCs but demonstrated weaker osteogenic effects on AFCs compared to BMP2. Specifically, fold changes in the expression of osteogenic markers on Day 21 showed BMP2 had a stronger effect than KMN159 in promoting the expression of genes such as ALP (2.828 vs 2.516), RUNX2 (4.199 vs 0.863), BGLAP (2.035 vs 0.7028), SPP1 (6.407 vs 1.078), SP7 (42.20 vs 1.094), and COL1 (1.664 vs 0.9518). When KMN159 was combined with BMP2 and L51P, there was a significant increase in ALP expression in AFCs (p < 0.05), suggesting enhanced osteogenic differentiation. This result was corroborated by increased ALP protein activity on Day 14 and intensified calcium deposition detected by ALZR staining on Day 21. Although other bone-related markers did not show statistically significant changes, an upward trend in expression was observed after 21 days. KMN159 had minimal impact on BMP antagonists (Noggin, Gremlin 1, and Chordin), indicating its minimal influence on their expression. Conclusion: Our results suggest that the combination of KMN159, BMP2, and L51P can successfully induce osteogenic differentiation in human AFCs. This combination may serve as a promising minimally invasive approach to enhance spinal fusion without the need to remove the intervertebral disc, offering potential new treatment options for patients suffering from lower back pain.

ID: 2009

A219: Is intradiscal injection of autologous bone marrow aspirate concentrate following lumbar microdiscectomy safe?

Alikhan Fidai ¹ , Jessica Berger ² , Ashley Cardenas ¹ , Chibuikem Ikwuegbuenyi ² , Blake Boadi ² , Jonathan Dyke ³ , Ibrahim Hussain ² , Lawrence Bonassar ¹ , Roger Härtl ²

¹ Cornell University, 1. Meinig School of Biomedical Engineering, Ithaca, United States,

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

³ Weill Cornell Medicine, Department of radiology, New York, United States

Introduction: Lumbar disc herniation patients face a higher risk of chronic lower back pain due to degeneration. Intradiscal injection of autologous bone marrow aspirate concentrate (BMAC) shows promise in treating early-stage intervertebral disc (IVD) degeneration, reducing pain and disability. However, the safety of BMAC post-microdiscectomy remains unclear. This study evaluates the safety of BMAC injections following microdiscectomy by assessing clinical outcomes and adverse events. Material and Methods: This prospective, single-center safety study included patients aged 18 years or older with degenerative disc disease who failed non-operative treatments for at least 3 months or had neurological deficits. Patients undergoing tubular lumbar microdiscectomy with concurrent BMAC injection were included. The primary outcome was safety, tracked via adverse events. Secondary outcomes included patient-reported outcomes (PROMs) like the Oswestry Disability Index (ODI) and Numeric Rating Scale (NRS) for back and leg pain, measured pre-operatively and at 3, 6, and 12 months. Radiological outcomes were assessed using T2 and T1-rho MRI scans to quantify changes in disc hydration, proteoglycan content, and nucleus pulposus (NP) size. Treated intervertebral discs (IVDs) were segmented using a Gaussian mixture model applied to first echo T2 and T1-rho images, with histograms fit to two normal distributions for background and disc tissue. A 2-5 standard deviation threshold from the background peak was applied for manual segmentation. T2 intensity, T1-rho intensity, and NP size were calculated and normalized against adjacent healthy controls. Statistical analysis used one-way ANOVA to evaluate PROM changes and radiological outcomes, with correlations analyzed via a generalized linear model. Results: Twenty-seven patients (mean age: 39.7 ± 14.7 years, 55.6% male) underwent lumbar microdiscectomy with concurrent intradiscal BMAC injection, predominantly L4- 51 (63%) level. One patient (3.7%) experienced same-site recurrent herniation, with no other complications reported. PROMs from 22 patients significantly improved (p < 0.0001) at all time points. Mean ODI decreased from 38 pre-operatively to 35 (3 months), 22 (6 months), and 13.5 (1 year). NRS-back scores decreased from 7 to 4, 2, and 1, while NRS-leg scores improved from 6 to 2, 1, and 0 at respective intervals. Radiological outcomes from 5 patients (15 discs) at one year showed increased T2 relaxation times (p < 0.05). T1-rho mapping revealed decreased proteoglycan content at three months, increasing at one year. NP size increased in three patients and decreased in two (p = 0.359). Strong correlations were found between T1-rho intensities and NRS-back (R = 0.68) and NRS-leg (R = 0.65), while T1-rho and ODI were also correlated (R = 0.58). Conclusion: Intradiscal BMAC injection following lumbar microdiscectomy appears safe, with significant improvements in pain and disability. Radiological findings suggest potential benefits in disc hydration and disc health. Future studies with control groups are needed to confirm these findings and further investigate the long-term regenerative effects of BMAC on IVDs.

ID: 2489

A220: Proteome differences in the annulus fibrosus between non-deformity degenerative and degenerative scoliosis patients

Taylor Bader ¹ , Zoe Myers ² , Manmeet Dhiman ¹ , David Hart ¹ , Holly Sparks ¹ , Neil Duncan ¹ , Paul Salo ¹ , Antoine Dufour ¹ , Ganesh Swamy ¹

¹ University of Calgary, Calgary, Canada,

² University of Ottawa, Ottawa, Canada

Introduction: Degenerative scoliosis (dScoli) can result from a decreased stability of the spinal units. The resulting translation results in considerable amounts of pain and immobility, sometimes requiring surgical treatment. Disproportionately, 84% of surgical treatments for dScoli is performed on post-menopausal females. It is unknown why some patients do not have translations associated with intervertebral disc degeneration (degen), while others develop dScoli. Mechanical changes of the annulus fibrosus (AF) may explain differences. We previously found reductions in the shear modulus in excised AF from dScoli patients as compared to non-deformity degenerative patients (Bader et al. ORS PSRS 2022). Here, we further explain the mechanical differences by examining the extracellular matrix proteome and N-terminomics of the AF in dScoli patients, as compared to degenerative and non-degenerative controls. Methods: AF samples were obtained during surgery for degenerative and dScoli cases and non-degenerative controls were donated through the Southern Alberta Organ Donation Program (University of Calgary Ethics ID: REB 18-1308). Small sections of the outer AF were snap frozen to -80°C within 15-minutes of sample collection. Protein extraction, trypsin digestion, shotgun proteomics, and N-terminomics using TAILS (Terminal Amine Isotopic Labelling of Substrates) were performed with standard techniques. Label-free analysis allowed for the comparison of multiple sample groups. After LC-MS/MS analysis, data was analyzed using MaxQuant. TopFIND was used for substrate cleavage site identification and Metascape and STRING for pathway enrichment analysis. To identify proteins of interest in both proteomics and N-terminomics, only hits found in > 50% of samples and with a 2-fold change were included. Results Section: A total of 24 patients and donation samples were collected. Using shotgun proteomics, we found 177 significant differently elevated proteins between non-degenerative and degenerative groups and 22 between degenerative and dScoli groups (p < 0.05, fold change > 2). Proteases upregulated in degen include increases in HTRA1, cathepsin B, and cathepsin D. In dScoli patients, increases in HTRA1, HTRA3, and MMP-3 were found. Enrichment pathways found increased neovascularization, innervation, and inflammation within dScoli patients. TAILS analysis detected novel increased proteolytic processing of HTRA1 (5-fold increase) within dScoli patients compared to degenerative cases. HTRA1 proteolytic processing were not found in any of the normal samples and notable substrates were increased within dScoli patients. Discussion: Using shotgun proteomics, increased neovascularization, innervation, and inflammatory factors were characterized in dScoli samples as compared to non-deformity and degenerative samples. HTRA1 was elevated in the dScoli patients, potentially leading to increased MMP-3 expression within IVD. Recent studies have found increased HTRA1 linked to increased expression of MMP-3, MMP-13, and disc degeneration. Further validation of its role will include activity-based probes, which confirm if specific types of proteases are active, and immunohistochemical staining to confirm its activation and spatial distribution within the tissue. There were no sex differences found in any condition. It remains unclear how these proteases influence the AF extracellular matrix and create changes in shear stiffness, which we believe leads to dScoli translations. Deeper characterization of the extracellular matrix will expand our understanding of differences between these conditions and continue to highlight differences in the disease processes. Significance: Changes in the AF proteome of deformity and non-deformity patients has not been well characterized, despite it potentially contributing to spinal degeneration and deformities. Proteomes and inflammatory pathways changes will be further characterized through activity-based probes of potential protease and extracellular matrix enrichment to explain why some patients, primarily post-menopausal women, develop these debilitating conditions. Specifically, we hope to explore the therapeutic role of HTRA1 inhibitors in intervertebral disc degeneration and spinal deformities.

ID: 1345

A221: Prospective study on serum protein biomarkers for diagnosis and prognosis in degenerative cervical myelopathy

Aditya Vedantam ¹ , Mahmudur Rahman ¹ , Sakib Salam ² , Anjishu Banerjee ² , Kajana Satkunendrarajah ¹ , Matthew Budde ¹ , Timothy Meier ¹

¹ Medical College of Wisconsin, Neurosurgery, Milwaukee, United States,

² Medical College of Wisconsin, Biostatistics, Milwaukee, United States

Introduction: Degenerative cervical myelopathy (DCM) is the most common cause of non-traumatic spinal cord injury worldwide. Many of the early symptoms of DCM are subtle, difficult to confirm on clinical examination, and may be confounded by co-morbid conditions. This leads to a delay in diagnosis and surgical intervention, which contributes to poorer recovery of neurological function. To better identify patients who will benefit from surgery, there is a need for additional objective assessments of spinal cord structure and function. Serum proteins are promising targets for biomarker discovery in DCM due to the ease of obtaining biospecimens, the potential for repeated sampling, and objective quantification. The objective of this study was to profile serum protein biomarkers in DCM and determine their potential diagnostic and prognostic utility in DCM. Methods: Patients clinically diagnosed with DCM (n = 20) and scheduled to undergo decompressive surgery were prospectively enrolled from July 2022 to August 2023. We excluded patients with trauma, syringomyelia, cord hemorrhage, tumor, pregnancy, and other neurological or muscular diseases that could explain their symptoms, as well as those with a history of prior cervical spine surgery. Serum neuronal and inflammatory proteins were quantified before surgery and at 3 months after surgery for DCM patients using ultrasensitive single-molecular array technology. Serum protein levels were compared between DCM patients and age- and sex-matched healthy controls (n = 10). Multivariable regression with variable selection was used to estimate the association between protein biomarkers and functional measurements (pre-surgery and post-surgery at 3 months). Results: DCM patients had a median age 70 years and healthy controls had a median age 65 years. Pre-surgical NfL (30.2 vs 11.2 pg/ml, p = 0.01) and IL-6 (2.9 vs 1.2 pg/ml, p = 0.003) were significantly higher in DCM patients compared to controls. Pre-surgical NfL, IL-6 and BDNF best differentiated DCM and controls (p < 0.001). The combined panel of NfL, IL-6, and BDNF demonstrated an area under the curve of 0.83 (95% CI 0.68-0.98) for diagnostic accuracy. At 3 months after surgery, serum BDNF (p = 0.001), AB-42 (p = 0.042) and TNFa (p = 0.007) were significantly increased compared to pre-surgical values. Pre-surgical serum NfL was significantly associated with improvement in pinch strength after surgery (p = 0.03). Multiple inflammatory biomarkers (IL-6, IL-10, IL-22) were linked to improvement in the neck pain-related disability and upper limb function. Conclusion: Pre-surgical serum levels of NfL, IL-6, and BDNF show potential as diagnostic markers for DCM. Pre-surgical serum biomarkers of neuronal damage and inflammation predict early post-surgical functional outcomes in DCM. Future validation of these results could enhance clinical decision-making for patients with DCM.

ID: 2215

A222: Link N modulates markers of pain and inflammation in the intervertebral disc through interaction with interleukin-1beta

Michael Grant ¹ , Muskan Alad ¹ , Laura Epure ¹ , John Antoniou ¹ , Fackson Mwale ¹

¹ McGill University, Montreal, Canada

Introduction: Chronic low back pain is often associated with degeneration of the intervertebral disc (IVD). IVD degeneration is typically characterized as proteolytic degradation of the extracellular matrix. However, disc cells from painful degenerative discs have been demonstrated to express pro-inflammatory cytokines such as interleukin-1β (IL-1β) and neurotrophic factors (i.e. NGF, BDNF). Treating chronic back may require both restoration of disc extracellular matrix and downregulation of painful factors. At the moment, there is no medical treatment to reverse or even retard disc degeneration. It has been previously shown that Link N, a peptide derived from the degradation of Link protein, can promote extracellular matrix regeneration in vitro and in vivo in a rabbit annular needle puncture model of IVD degeneration. Evidence indicates that Link N partially activates Smad1/5 signaling in disc cells by interacting with the bone morphogenetic protein (BMP) type II receptor. Whether Link N can alter the signaling pathways of other factors such as IL-1β in disc cells remains unknown. Material and Methods: Human NP disc cells were cultured as micro-pellets for gene expression analysis using qPCR. Cells were exposed to IL-1β (5 ng/ml), human Link N (hLN) (1μg/ml) or co-incubated with IL-1β+hLN for 7 days. To determine the effect of Link N on IL-1β signalling, NFκB activation was assayed by Western blotting for detection of P-p65 following 10 min exposure of IL-1β in the presence of 10, 100, or 1000 ng/mL hLN. Peptide docking of Link N to IL-1β was determined using CABS-dock web server. Immunoprecipitation was performed to validate docking results. To determine the effect of LN on IL-1β-induced neuronal activity, we isolated murine DRG neurons from lumbar regions L2-5 and incubated them for 7 days with IL-1β [1 ng/mL] with or without LN [1μg/mL]. Ca-immobilization assays were performed to measure for changes in hyperactivity. Results: Link N significantly decreased in a dose-dependent manner IL-1β-induced NF-κB activation in disc cells. Modulation on the biological effects of IL-1β-induced gene expression profiling of matrix proteins, catabolic enzymes, inflammatory and neurotrophic factors by Link N was associated with the degree of NF-κB inhibition. Peptide docking simulations indicated that Link N could interact with IL-1β even when IL-1β was docked to its receptor IL1R1. Immunoprecipitation revealed direct interactions of Link N with IL-1β. When DRG neurons were incubated with IL-1β, basal intracellular Ca2+ levels were elevated when compared to controls (p < 0.001; n = 4). LN significantly decreased basal Ca2+ levels when compared to IL-1β (p < 0.0001; n = 4). When DRG neurons were stimulated with capsaicin, IL-1β preconditioned neurons demonstrated a sustained increase in intracellular Ca2+. Co-treatment with LN blunted the sustained Ca2+ increase induced by IL-1β. Conclusion: We demonstrate that Link N directly interacts with IL-1β to inhibit its function. Link N was not only able to inhibit the effects of IL-1β on disc cells but was also capable of regulating IL-1β-induced DRG hypersensitivity. These results may support the use of Link N in the treatment of discogenic pain through regulation of IL-1β.

ID: 1304

A223: Regulatory effect of elastase on bone metabolism

Zhen Jin ¹ , Saihu Mao ¹

¹ Nanjing Drum Tower Hospital, Nanjing, China

Objective: To explore the effects of elastase on bone mass and its underlying mechanisms. Methods: We conducted a study using male C57BL/6J (WT) mice, along with globally overexpressed elastase (AAV9-Elastase) and elastase knockout (Elastase KO) mouse models. A human study included 84 patients over the age of 50 who underwent spinal surgery. Multiple methods were used to evaluate bone health in both mice and humans, including micro-CT, dual-energy X-ray absorptiometry (DXA), calcein labeling, histological analysis, RNA-seq, ELISA, Western blotting, and biomechanical testing. Results: Elastase KO mice exhibited significant bone loss. Adult mice overexpressing elastase through AAV9 showed notable increases in bone mass. Elastase was found to promote bone formation by osteoblasts while inhibiting bone resorption by osteoclasts. Clinically, elastase, an essential secretory protease, showed a significant positive correlation with bone mineral density in patient plasma samples. Conclusion: Elastase plays a crucial role in regulating bone metabolism and may serve as a potential therapeutic target for osteoporosis.

Keywords: Elastase, Bone Metabolism, Osteoporosis

ID: 1657

A224: 3D-printed, bi-layer, biomimetic artificial periosteum for boosting bone regeneration

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

¹ Tianjin Medical University, Tianjin, China,

² Tianjin University Tianjin Hospital, Tianjin, China,

³ Tianjin University, Tianjin, China

Objective: Periosteum, a membrane covering the surface of the bone, plays an essential role in maintaining bone tissue function, particularly in nourishment and vascularization during bone regeneration. However, current artificial periostea lack sufficient mechanical strength, degrade rapidly, and fail to integrate angiogenesis and osteogenesis functions. This study aims to address these shortcomings by fabricating a bi-layer, biomimetic, artificial periosteum using 3D printing technology. Methods: Hydrogels were prepared via photoinitiated radical polymerization. Gelatin methacrylate (GelMA) served as the primary ink, with nano-hydroxyapatite (nHA) incorporated to form the cambium layer (GelA-nHA). Copolymerization of GelMA with ACG stabilized the fibrous layer's transient network, ensuring appropriate in vivo degradation. Results: GelMA hydrogel exhibited low tensile stress, which significantly increased upon nHA inclusion, reaching 116.28 kPa tensile stress and 236.18 kPa tensile modulus with 67% nHA content. The P(ACG-GelMA)-Mg2+ hydrogel demonstrated higher mechanical strength compared to GelMA hydrogel-based periosteum. Both layers exhibited excellent biocompatibility (> 95% cell viability). Magnesium ion addition reduced pro-inflammatory cytokine expression and promoted M2 macrophage polarization and angiogenesis, as evidenced by increased VEGF and HIF-1α expression. Conclusion: A bi-layer, biomimetic artificial periosteum was successfully fabricated via 3D printing. GelMA-nHA formed the cambium layer with appropriate mechanical properties and degradation behavior, while P(ACG-GelMA)-Mg2+ comprised the outer fibrous layer, providing mechanical support and prolonged degradation. Magnesium ions regulated immune response and angiogenesis. This bi-layer scaffold facilitated efficient bone regeneration in critical size bone defects in rats by integrating immune modulation, angiogenesis, and osteogenesis functions.

Key words: 3D printing, Bi-layer periosteum scaffold, Immune regulation, Bone regeneration

ID: 1013

A225: Characteristics of gut microbiota and metabolites in postmenopausal women with osteoporosis

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

¹ Xuanwu Hospital Capital Medical University, Beijing, China

Introduction: Women often suffer from osteoporosis and metabolic diseases after menopause, and recently it has been confirmed that gut microbiota plays an important role in regulating the bone homeostasis microenvironment. Therefore, exploring the differences in gut microbiota and metabolites between postmenopausal women with osteoporosis and those with normal bone mass has important clinical significance. The aim of this study is to compare the gut microbiota characteristics and fecal metabolite changes between postmenopausal osteoporosis and normal bone women, and to preliminarily reveal new strategies for treating postmenopausal osteoporosis. Material and Methods: This study recruited 128 postmenopausal women for testing of gut microbiota and fecal metabolites. Among them, 76 patients who met the inclusion criteria were divided into postmenopausal osteoporosis (OP) group and postmenopausal normal bone (HC) group based on bone density (BMD). The composition of intestinal bacteria was detected by 16S rRNA gene sequencing, and fecal metabolites were analyzed by liquid chromatography-mass spectrometry (LC-MS). Results: 16S rRNA gene sequencing analysis found that compared with the HC group patients, the alpha diversity and beta diversity of the gut microbiota in the OP group patients were significantly altered. At the genus level, the enrichment of Bacteroidetes in the OP group was significantly negatively correlated with BMD, while the enrichment of Prevotella and Roche in the HC group was significantly positively correlated with BMD. Metabolomics analysis revealed significant changes in fecal metabolites such as acetic acid and N-acetylneuraminic acid, as well as their corresponding signaling pathways, particularly in the metabolism of alpha linolenic acid and selenium compounds. Conclusion: Postmenopausal women experience significant changes in gut microbiota and fecal metabolites, which are significantly correlated with BMD. These correlations provide new insights into the mechanism of PMO and the relationship between bone homeostasis and microbiota in postmenopausal women.

OP26: Novel Concepts in Spine Surgery

ID: 763

A226: Cervical extensor muscles involution in patients with symptomatic degenerative conditions: comparative analysis and impact on alignment parameters

Enrico Giordan ¹ , Brando Guarrera ¹ , Cristina Cuppone ¹ , Giuseppe Canova ¹

¹ AULSS2 Marca Trevigiana, Neurosurgery, Treviso, Italy

Introduction: In recent years, researchers have studied the impact of fatty infiltration (FI) of lumbar paraspinal muscles on instability and pain. FI is also commonly found in patients with cervical spine conditions such as whiplash, spinal cord injury, and degenerative myelopathy. Increased FI in the cervical flexor and extensor muscles has been linked to higher pain and disability. This study aims to analyze the composition of extensor muscles in preoperative imaging for patients undergoing cervical spine surgery, correlating them with cervical alignment and demographic parameters. Materials and Methods: This retrospective study looked at adult patients aged 18 and older who had surgery for cervical myelopathy in the last five years. We collected the type of intervention (anterior cervical discectomy and fusion (ACDF, SP group) or posterior laminectomy. ST group). The patients were divided into two groups based on the location of the compression: anterior, caused by spondylosis, and posterior, by single or multilevel compression, caused by degenerative changes of facet joints. Preoperative T2-weighted MRI for FI analysis and X-rays of the cervical spine for alignment collection were evaluated. We looked at the FI to muscle tissue (MA) ratio of paraspinal extensor musculature at each slice of the preoperative scans from C2–C7. Multiple uni and multivariate logistic regression models were used to compare cervical alignment, FI, and demographics. Results: We identified 143 patients; 78 were included in the spondylosis and 65 in the ST group. A significantly higher percentage of FI was found in ST patients than in SP (1.8% ± 2.6% vs. 5.0% ± 7.6%, p-value: 0.015, respectively). Multivariate analysis showed a correlation with lower odds of spondylosis development for lower values of T1S (OR 0.94, 95% CI 0.89 - 0.98, p-value: 0.017) as well as lower odds of developing spondylosis for lower values of FI (OR 0.83, 95% CI 0.71 - 0.98, p-value: 0.029). Conclusions: We found that patients with single or multilevel stenosis had a much higher degree of FI in the extensor muscles. Additionally, we observed significant differences in cervical lordosis and T1S values between the two groups, with patients with spondylosis showing significantly lower values of CL and T1S.

ID: 1106

A227: What's the harm? Evaluating complications associated with salvaged red blood cell transfusion in spinal deformity surgery: a non-randomized controlled trial

David Kurland ¹ , Anthony Frempong-Boadu ¹ , Darryl Lau ¹

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

Introduction: Salvaged red blood cells (sRBCs) are frequently used in spine surgery, despite concerns about their quality. Prior research has demonstrated that sRBCs collected in this setting suffer from significant hemolysis, abnormal deformability, and poor morphological integrity, questioning their efficacy as a blood substitute. This study aimed to evaluate the association of sRBC transfusion with postoperative complications in spinal deformity surgery. Material and Methods: This single-center, prospective, nonrandomized controlled trial included patients undergoing posterior-based multilevel thoracolumbar instrumented fusion for spinal deformity from June 2022 to July 2023. Participants were grouped based on whether they received sRBC transfusion. Postoperative complications were analyzed using frequentist methods, with and without propensity score matching (PSM), and a series of five Bayesian models of varying complexity that included hierarchical structures and covariates. Model comparison followed by weighted model averaging based on predictive performance was performed to to integrate the results from the different models into a composite model. Results: After PSM (specifically matching surgical invasiveness and blood loss), sRBC transfusion was associated with increased odds of infection (OR 3.77, 95% CI 0.99-14.33, p = 0.046), acute kidney injury (AKI, OR 3.36, 95% CI 1.37-8.22, p = 0.007), liver injury (OR 3.52, 95% CI 1.64-7.54, p = 0.001), pulmonary complications (OR 2.26, 95% CI 1.13-4.53, p = 0.025), and thrombocytopenia (OR 9.02, 95% CI 2.54-32.0, p < 0.001). The composite Bayesian model yielded consistent results, with additional associations noted for cardiac events (OR 2.18, 95% HDI 1.36–3.03) and coagulopathy (OR 3.13, 95% HDI 2.88-6.49). In contrast, allogeneic RBC transfusion was only associated with infection (OR 1.64, 95% HDI 1.04-2.59) and pulmonary complications (OR 1.73, 95% HDI 1.08-2.89). Conclusion: sRBC transfusion in complex spine surgery is independently associated with increased risks of various complications. These findings reinforce concerns about the safety of sRBC transfusion, suggesting a need for caution in their use in this setting.

ID: 73

A228: Long-term outcomes of operative versus nonoperative treatment for adult symptomatic lumbar scoliosis: durability of treatment effects and impact of related serious adverse events through 8-year follow-up

Justin Smith ¹ , Michael Kelly ² , Elizabeth Yanik ³ , Christine Baldus ³ , Vy Pham ³ , David Ben-Israel ¹ , Jon Lurie ⁴ , Charles Edwards ⁵ , Steven Glassman ⁶ , Lawrence Lenke ⁷ , Oheneba Boachie-Adjei ⁸ , Jacob Buchowski ³ , Leah Carreon ⁶ , Charles Crawford, III ⁶ , Stephen Lewis ⁹ , Tyler Koski ¹⁰ , Stefan Parent ¹¹ , Virginie Lafage ¹² , Munish Gupta ³ , Han Jo Kim ¹³ , Christopher Ames ¹⁴ , Shay Bess ¹⁵ , Frank Schwab ¹² , Christopher Shaffrey ¹⁶ , Keith Bridwell ³

¹ University of Virginia, Department of Neurosurgery, Charlottesville, United States,

² Rady Children's Hospital, San Diego, United States,

³ Washington University School of Medicine, St Louis, United States,

⁴ Dartmouth-Hitchcock Medical Center, Lebanon, United States,

⁵ Mercy Medical Center, Baltimore, United States,

⁶ Norton Leatherman Spine Center, Louisville, United States,

⁷ Columbia University, New York City, United States,

⁸ FOCOS Orthopedic Hospital, Accra, Ghana,

⁹ University of Toronto, Toronto Western Hospital, Toronto, Canada,

¹⁰ Northwestern University, Chicago, United States,

¹¹ Sainte-Justine University Hospital, Montreal, Canada,

¹² Lennox Hill Hospital, New York City, United States,

¹³ Hospital for Special Surgery, New York City, United States,

¹⁴ University of California San Francisco, San Francisco, United States,

¹⁵ Denver International Spine Center, Presbyterian St. Luke’s/Rocky Mountain Hospital for Children, Colorado, United States,

¹⁶ Duke University, Durham, United States

Introduction: The most common type of adult spinal deformity is lumbar scoliosis, resulting from either residual adolescent idiopathic scoliosis or from degeneration. Long-term follow-up studies of operative and nonoperative treatment of adult symptomatic lumbar scoliosis (ASLS) are needed to assess benefits and durability. Our objectives were to assess the long-term outcomes of operative versus nonoperative treatment for ASLS, including the durability of each treatment approach, and to assess the rates of serious adverse events (SAEs) and their potential impact on outcomes. Material and Methods: The ASLS-1 study is an NIH (2010-2017) and Scoliosis Research Society (SRS; 2017-present) sponsored multicenter prospective study to assess operative versus nonoperative treatment for ASLS, with randomized and observational treatment arms. Patients were 40-80 years old with ASLS (Cobb > 30^o and Oswestry Disability Index (ODI) > 20 or SRS-22 subscore < 4.0 in pain, function and/or self-image). Operative and nonoperative patients were compared using as-treated analysis, and the impact of related SAEs was assessed. Results: The 286 enrolled patients (104 nonoperative, 182 operative) had follow-up rates at 2, 5, and 8 years of 90% (256), 70% (199), and 72% (205), respectively. At 2 years, compared with nonoperative, operative patients had greater improvement in ODI (mean difference = -12.98 [95%CI, -16.08 to -9.88], p < .001) and SRS-22 (mean difference = 0.57 [95%CI, 0.45 to 0.70], p < .001), with mean differences exceeding minimal detectable measurement difference (MDMD) for ODI (7) and SRS-22 (0.4). Mean differences at 5 years (ODI = -11.25 [95%CI, -15.20 to 7.31], SRS-22 = 0.58 [95%CI, 0.44 to 0.72], p < .001 for both) and 8 years (ODI = -14.29, [95%CI, -17.81 to -10.78], SRS-22 = 0.74 [95%CI, 0.57 to 0.90], p < .001 for both) remained as favorable as at 2 years without evidence of degradation. The treatment-related SAE incidence rates for operative patients at 2, 2-5, and 5-8 years were 22.24, 9.08, and 8.02 per 100 person-years, respectively. At 8 years, operative patients with one treatment-related SAE still had significant improvement, with mean treatment differences that exceeded MDMD (ODI = -9.5 [95%CI, -14.3 to -4.8], SRS-22 = 0.62 [95%CI, 0.41 to 0.84], p < .001 for both). The 22 operative patients with 2+ SAEs at 8 years had significant improvement of both SRS-22 (mean difference = 0.49, p = 0.0002) and ODI (mean difference = -6.0, p = 0.0381) compared to nonop treatment, but only the SRS-22 mean difference exceeded MDMD. Conclusion: Operative treatment for ASLS provided significantly greater clinical improvement than nonoperative treatment at 2-, 5- and 8-year follow-up, with no evidence of deterioration over time. Operative patients with a treatment-related SAE maintained greater improvement than nonoperative patients. These findings demonstrate long-term durability of surgical treatment for ASLS and should prove useful for patient management and counseling.

ID: 2474

A229: Percutaneous endoscopic lumbar discectomy combined with platelet-rich plasma injection for the treatment of lumbar disc herniation: a meta-analysis of clinical outcomes

Kaike Eduardo da Silva Lobo ¹ , Cláudia Santos ² , Paweł Łajczak ³ , Numa Rajab ⁴ , Gabriela Nascimento ⁵ , Leonardo Santos ¹ , Yan Silva ⁶

¹ State University of Pará, Belém, Brazil,

² FG University Center, Brumado, Brazil,

³ Medical University of Silesia, Katowice, Poland,

⁴ Sulaiman Al Rajhi University, Al Bukairyah, Saudi Arabia,

⁵ Escola Superior de Ciências da Santa Casa de Misericórdia de Vitória, Vitória, Brazil,

⁶ Hospital Ortopédico do Estado, Salvador, Brazil

Introduction: Lumbar disc herniation (LDH) is a prevalent spinal condition for which minimally invasive surgical treatments, such as percutaneous endoscopic lumbar discectomy (PELD), are increasingly gaining popularity. Recently, platelet-rich plasma (PRP) injections have gained attention for their potential to improve clinical outcomes and enhance intervertebral disc repair. However, current evidence regarding the combined use of PELD with PRP injection for treating LDH remains limited. Therefore, we conducted a meta-analysis to evaluate their combined effects. Material and Methods: We systematically searched PubMed, Embase, Cochrane Library, and Web of Science for randomized controlled trials and observational studies evaluating patients undergoing PELD, with versus without the addition of PRP injection. The outcomes assessed included Visual Analog Scale (VAS) scores for leg and back pain, Japanese Orthopaedic Association (JOA) score, Oswestry Disability Index (ODI), MacNab criteria excellent or good rate, and recurrence rate. Mean difference (MD) and odds ratio (OR) were calculated for continuous and binary outcomes, respectively, with 95% confidence interval (CI). Results: Of 239 articles screened, 5 studies were included, with a total of 469 patients undergoing PELD, 230 (49%) treated with the addition of PRP injection and 239 (51%) without. PRP injection significantly reduced VAS back pain scores at 3 months (MD -0.35; 95% CI -0.65, -0.06; p = 0.02; I² = 81%), 6 months (MD -0.53; 95% CI -0.84, -0.22; p < 0.01; I² = 87%), and 1 year (MD -0.30; 95% CI -0.45, -0.14; p < 0.01; I² = 0%) postoperatively. PRP injection also decreased VAS leg pain scores at 3 months (MD -0.26; 95% CI -0.40; -0.13; p < 0.01; I² = 37%), 6 months (MD -0.31; 95% CI -0.46; -0.16; p < 0.01; I² = 42%), and 1 year (MD -0.36; 95% CI -0.54; -0.17; p < 0.01; I² = 0%). Additionally, JOA scores were significantly higher in the PRP group at 3 months (MD 2.53; 95% CI 0.35; 4.71; p = 0.02; I² = 92%), 6 months (MD 1.14; 95% CI 0.61; 1.67; p < 0.01; I² = 0%), and 1 year (MD 0.99; 95% CI 0.40; 1.58; p < 0.01; I² = 0%). There was no significant difference between groups in ODI at 3 months (MD -1.67; 95% CI -5.81; 2.48; p = 0.43; I² = 87%), but PRP injection led to lower scores at 6 months (MD -3.26; 95% CI -5.67; -0.85; p < 0.01; I² = 57%) and 1 year (MD -4.41; 95% CI -8.16; -0.66; p = 0.02; I² = 82%). The excellent or good rate of the MacNab criteria was not significantly different (OR 1.48; 95% CI 0.76; 2.89; p = 0.252; I² = 0%), but the recurrence rate was lower in the PRP group (OR 0.24; 95% CI 0.09; 0.67; p = 0.006; I² = 0%). Conclusion: In this meta-analysis, the combination of PELD with PRP injection significantly improved pain relief, functional outcomes, and reduced recurrence rates in patients with LDH compared to PELD alone. Although further high-quality research is needed to strengthen the evidence, our findings suggest that PRP injection may enhance the effectiveness of PELD for treating LDH, offering a valuable adjunct in surgical care.

ID: 1256

A230: Clinical success of P-15 peptide enhanced bone graft in transforaminal lumbar interbody fusion: 2-year follow-up of a multicenter prospective randomized controlled trial

John O'Toole ¹ , Paul Arnold ² , Michael Steinmetz ³ , Christopher Chaput ⁴ , Rick Sasso ⁵ , James Harrop ⁶

¹ Rush University, Neurosurgery, Chicago, United States,

² Loyola University, Chicago, United States,

³ Cleveland Clinic Lerner College of Medicine, Cleveland, United States,

⁴ University of Texas Health Science Center at San Antonio, San Antonio, United States,

⁵ Indiana University School of Medicine, Carmel, United States,

⁶ Thomas Jefferson University, Philadelphia, United States

Introduction: Numerous bone graft options are available for spine arthrodesis. P-15 is a synthetic 15-amino acid polypeptide that mimics the cell binding domain of Type I collagen to enhance cell binding, proliferation, and differentiation leading to new bone formation. ABM/P-15 Matrix (Cerapedics Inc., Westminster, Colorado, USA), an FDA breakthrough device, is a composite bone graft incorporating the P-15 peptide. P-15’s mechanism of action is well established with a long clinical history. This analysis presents the safety and clinical success outcomes of the multicenter FDA Investigational Device Exemption (IDE) randomized clinical trial of ABM/P-15 Matrix versus local autograft in instrumented transforaminal lumbar interbody fusion (TLIF) for the treatment of degenerative disc disease (DDD) with up to Grade I spondylolisthesis. Material and Methods: Skeletally mature patients, aged 22-80 years, with DDD were 1:1 randomized to either ABM/P-15 Matrix or local autograft control during single-level TLIF with a PEEK cage and bilateral posterior pedicle fixation. The primary study outcome was a Composite Clinical Success (CCS) measure at 24 months, defined as having met all of the following criteria: no index level secondary surgical intervention; achievement of fusion (evidence of bridging trabecular bone between vertebral bodies via thin-slice computed tomography); ≥ 15-point improvement in Oswestry Low Back Pain Disability Questionnaire (ODI) from baseline; no new or worsening, persistent neurological deficit relative to baseline; and no serious device-related adverse events (AEs). Results: A total of 290 patients from 33 sites were enrolled; 141 (48.6%) patients (mean: 58.8 years) received ABM/P-15 Matrix, and 149 (51.3%) patients (mean: 59.6 years) received autograft. One hundred nineteen (84.4%) patients in the ABM/P-15 Matrix group and 128 (85.9%) in the autograft group were available for the 24-month follow-up. ABM/P-15 Matrix was both non-inferior (p < 0.0001) and superior (p = 0.002) to autograft with respect to the CCS, with 55.5% of the ABM/P-15 Matrix group achieving clinical success compared with 37.5% of the autograft group. Additionally, the fusion results for the ABM/P-15 Matrix group were 25.8% higher than those for the autograft group (84.3% and 58.5%, respectively), demonstrating statistically higher achievement of fusion using ABM/P-15 Matrix over autograft by 24 months (p < 0.0001). The autograft group had significantly more patients with no index level secondary surgical interventions (difference = 6.5%, 95% CI -11.9%, -1.1%). There were no significant differences between groups with respect to ODI improvement, neurological deficits (motor and sensory), and serious device-related AEs. There were no significant differences between groups in overall device-related AEs. Conclusion: In this FDA IDE pivotal, randomized, controlled study, ABM/P-15 Matrix was statistically superior to local autograft in overall clinical success and fusion 2-years after instrumented TLIF. No significant differences in the incidence of AEs were observed, indicating ABM/P-15 is as safe as local autograft.

ID: 2038

A231: Global practices and preferences in the use of osteobiologics for anterior cervical discectomy and fusion: a global cross-sectional study

Luca Ambrosio ¹ , Sathish Muthu ² , Pieter-Paul A. Vergroesen ³ , Zorica Buser ⁴ , Hans-Jörg Meisel ⁵ , Gianluca Vadalà ¹ , AO Spine Knowledge Forum Degenerative ⁶

¹ Campus Bio-Medico University Hospital Foundation, Rome, Italy,

² Government Medical College, Karur, India,

³ Noordwest Hospitals, Alkmaar, Netherlands,

⁴ Grossman School of Medicine, New York, United States,

⁵ G Klinikum Bergmannstrost Halle, Halle, Germany,

⁶ AO Spine, Davos, Switzerland

Introduction: Anterior cervical discectomy and fusion (ACDF) is a widely performed spine surgery. While decompression of neural structures is essential, long-term outcomes depend on achieving bony fusion, typically accomplished through instrumentation and osteobiologics. Autologous iliac crest bone graft (AICBG) is considered the gold standard, but donor site morbidity has prompted the development of alternative osteobiologics. Despite various options such as bone morphogenetic protein (BMP)-2, demineralized bone matrix (DBM), and others, inconsistent regulatory and clinical evidence leads to fragmented use. To address this issue, AO Spine has developed an international guideline, the AO Spine Guideline for the Use of Osteobiologics (AOGO), to assist the spine community in selecting the most appropriate osteobiologics based on the best available evidence. The aim of this study was to assess global practice patterns and preferences regarding the use of osteobiologics in ACDF, and to identify the factors influencing the selection of specific osteobiologics over others. Material and Methods: An online questionnaire assessing the use of osteobiologics in ACDF was sent to AO Spine members globally, gathering demographic, clinical, and practice-related data. Information regarding previous formal training in the use of osteobiologics, awareness of osteobiologic costs, use of implants in ACDF surgeries (i.e., cages and plates), frequency of osteobiologic use in ACDF, strategies to reduce complications and improve treatment outcomes, and factors influencing the use of osteobiologics in ACDF. Statistical analyses, including chi-square tests and logistic regression, were used to identify associations between osteobiologic use and various factors such as surgeon experience, training, geographic location, and economic considerations. Results: A total of 458 surgeons participated, with representation from various global regions. Most respondents were male, aged 35-44, and had been practicing for at least five years. Notably, 79.7% of surgeons had not received formal training in osteobiologics, and 53.1% were unaware of the costs associated with these materials. The use of osteobiologics varied significantly by region (p < 0.0001), with AICBG more common in Asia-Pacific, while allografts and DBM were more frequently used in North America and Europe. Factors influencing the choice of osteobiologics included evidence base, availability, and cost. Surgeons in rural areas and those with fewer ACDF cases per year were less likely to use osteobiologics. Conclusion: The study highlights considerable variability in the use of osteobiologics for ACDF, influenced by surgeon training, regional practices, and economic factors. A lack of formal training and awareness of costs underscores the need for more structured education and dissemination of standardized guidelines, such as the AOGO. Addressing these gaps could lead to more consistent and effective use of osteobiologics, ultimately improving patient outcomes. Future research should aim to provide higher-quality evidence and strategies to enhance guideline adoption in clinical practice.

ID: 281

A232: Efficacy of a needle-shaped biphasic calcium phosphate ceramic versus autograft in instrumented posterolateral spinal fusion: a multicenter randomized controlled noninferiority trial with intrapatient design

Katherine Sage ¹ , Diyar Delawi ² , Diederik Kempen ³ , Eric Hoebink ⁴ , Job van Susante ⁵ , Moyo Kruyt ⁶

¹ Kuros Biosciences, Atlanta, United States,

² St. Antonius Ziekenhuis, Nieuwegein, Netherlands,

³ OLVG Amsterdam, Amsterdam, Netherlands,

⁴ Amphia, Nieuwegein, Netherlands,

⁵ Rijnstate, Arnhem, Netherlands,

⁶ UMC Utrech, Utrecht, Netherlands

Introduction: Successful spinal fusion with a solid bone bridge between the vertebrae is traditionally achieved by grafting with autologous iliac bone. However, the disadvantages of autograft and unsatisfactory fusion rates have prompted the exploration of alternative bone grafts. This study investigates a slowly resorbable biphasic Calcium Phosphate bone graft with submicron microporosity (BCP < μm) as an alternative for autograft. Material and Methods: Adults indicated for lumbar posterolateral fusion (PLF; one to six levels) were enrolled at five participating centers. After bilateral instrumentation and fusion-bed preparation, the randomized allocation side (left or right) was disclosed. Per segment 10cc of BCP < μm granules (1-2 mm) was placed in the posterolateral gutter on one side and 10cc autograft on the contralateral side. Fusion was systematically scored on one-year follow-up CT scans. The study was powered to detect > 15% inferiority with binomial paired comparisons of the fusion performance score per treatment side. At segment level, a Generalized Estimating Equations (GEE) model was used accounting for clustering of fusions within segments and within patients. Results: Out of 100 patients (57 ± 12.9 years, 62% female), 91 subjects and 128 segments were analyzed. The overall posterolateral fusion rate per segment (left and/or right) was 83%. For the BCP < μm side the fusion rate was 79% vs. 47% for the autograft side (difference 32 percentage points, 95% CI = 23 to 41). The estimated odds ratio was 4.2 (95% CI = 2.7 to 6.8) in favor of the BCP < μm. Analysis of the primary outcome confirmed the non-inferiority of BCP < μm with an absolute difference in paired proportions of 39.6% (95% CI = 26.8 to 51.2%, p < 0.001). Conclusion: This clinical trial demonstrates non-inferiority and even superiority of BCP < μm as a standalone ceramic compared to autograft for posterolateral spinal fusion. Further studies are needed to confirm these findings, but these results challenge the belief that autologous bone is the optimal graft material.

ID: 1595

A233: Faster fusion with P-15 enhanced bone graft in transforaminal lumbar interbody fusion: analysis of radiological outcomes of a multicenter, prospective, randomized controlled trial

John O'Toole ¹ , Paul Arnold ² , Michael Steinmetz ³ , Christopher Chaput ⁴ , Rick Sasso ⁵ , James Harrop ⁶

¹ Rush University, Chicago, United States,

² Loyola University, Chicago, United States,

³ Cleveland Clinic Lerner College of Medicine, Cleveland, United States,

⁴ University of Texas Health Science Center at San Antonio, San Antonio, United States,

⁵ Indiana University School of Medicine, Carmel, United States,

⁶ Thomas Jefferson University, Philadelphia, United States

Introduction: Autologous bone is considered the gold standard in spine fusion; however, numerous substitute biomaterials are now available. ABM/P-15 Matrix (Cerapedics Inc., Westminster, Colorado, USA), an FDA breakthrough device, is a composite bone graft incorporating P-15, a synthetic peptide that mimics the cell-binding domain of Type I collagen. P-15 has been shown in preclinical and clinical studies to significantly enhance attachment of osteogenic precursor cells and osteoblast differentiation, thus leading to generation of new bone. This analysis presents the radiological fusion outcomes from a multicenter, randomized controlled study comparing ABM/P-15 Matrix as the treatment and local autologous bone graft as the control in treating degenerative disc disease (DDD) using instrumented transforaminal lumbar interbody fusion (TLIF). Material and Methods: Skeletally mature patients, aged 22-80 years, with DDD were enrolled at 33 sites and randomized 1:1 to either the ABM/P-15 Matrix treatment group or the local autograft control group during single-level TLIF with a PEEK cage and bilateral pedicle screw fixation. Fusion assessments occurred at 6-, 12-, and 24-months. Fusion was evaluated by two independent radiologists and defined as evidence of continuous bridging trabecular bone from endplate to endplate by high resolution thin-slice computed tomography (CT) scans (1 mm slices with 1 mm index on axial, sagittal, and coronal reconstructions). Once fusion was radiographically confirmed, it was assumed fusion had occurred at all subsequent time points. Time-to-fusion was pre-specified as a superiority effectiveness endpoint and tested using the Kaplan-Meier survival rate. Results: A total of 141 (48.6%) patients received ABM/P-15 Matrix and 149 (51.3%) patients received autograft. One hundred twenty-seven (90.1%) patients in the ABM/P-15 Matrix group and 130 (87.2%) in the autograft control group were available for the 24-month imaging follow-up. ABM/P-15 Matrix promoted significantly faster fusion than autograft. Significantly more patients in the ABM/P-15 Matrix group than the autograft group achieved fusion at 6 months (59.7% vs 28.7%, respectively), 12 months (72.9% vs 44.1%, respectively), and 24 months (84.3% vs 58.5%, respectively) (p < 0.0001 for all). The ABM/P-15 Matrix group was 44% more likely to fuse by Month 24 compared with the autograft group. Further, using the Kaplan-Meir survival rate, there is robust statistical evidence that the time-to-fusion is shifted toward earlier times for ABM/P-15 Matrix relative to the autograft control, demonstrating superiority of ABM/P-15 Matrix over autograft for faster time-to-fusion (p < 0.0001). Conclusion: Significantly higher fusion rates were observed in patients treated with ABM/P-15 Matrix compared to those treated with autograft. The difference in fusion rates were statistically higher in favor of ABM/P-15 Matrix at 6-, 12- and 24-month follow-up. The results from these analyses demonstrate that ABM/P-15 Matrix promotes faster fusion and statistically superior earlier time-to-fusion than local autograft in instrumented TLIF.

ID: 1655

A234: P-15 peptide enhanced bone graft in cervical spine fusion: radiological and clinical outcomes from a prospective, multicenter clinical study

Bradley Jacobs ¹ , Christopher Witiw ² , Zhi Wang ³ , Perry Dhaliwal ⁴ , Carlo Santaguida ⁵ , Chris Bailey ⁶

¹ University of Calgary, Calgary Spine Program, Calgary, Canada,

² University of Toronto, Division of Neurosurgery, St. Michael's. Hospital, Toronto, Canada,

³ University of Montreal, Department of Orthopaedics, Montreal, Canada,

⁴ University of Manitoba, Section of Neurosurgery, Department of Surgery, Winnipeg, Canada,

⁵ McGill University, Department of Neurology and Neurosurgery, Montreal, Canada,

⁶ Western University, Division of Orthopaedics, London, Canada

Introduction: Anterior Cervical Discectomy and Fusion (ACDF) and Posterior Cervical Fusion (PCF) are common procedures in the treatment of degenerative conditions of the cervical spine. Successful arthrodesis is critical to favorable long-term outcomes. Both fusion technique and bone graft material choice have significant impact on arthrodesis. P-15 Peptide Enhanced Bone Graft (ABM/P-15 Matrix), is one such bone graft option. This abstract reports the early clinical and radiological outcomes associated with the use of ABM/P-15 Matrix in single and multi-level cervical procedures in a multi-center clinical trial. Materials and Methods: A prospective on-label study was conducted in six hospitals in Canada. Adult participants requiring cervical spinal fusion, between levels C2-T2, were included. Neurological status, relevant clinical history, Neck Disability Index (NDI), 12-Item Short Form Survey (SF-12), Numeric Pain Rating Scale (NRS) and Modified Japanese Orthopaedic Association (mJOA) were collected at baseline, 6-, 12- and 24-months. Active smoking, obesity (BMI > 30) and diabetes were considered high-risk factors. A thin-cut (< 1 mm) CT was acquired at 12-months and assessed for fusion status by an independent core-lab (Medical Metrics Inc.). Fusion status was reported by both participant and operative segment. Fusion status was reported at both the segmental and participant level. Adverse events and reinterventions at the index level were recorded. Results: A total of 76 participants (45 PCF participants, 31 ACDF participants) with 238 total operative levels (mean years and standard deviation of age 57.3 ± 11.9 for ACDF and 62.9 ± 10.4 for PCF; 47 male, 29 female) were included. 68.4% of participants presented with 1 or more high-risk comorbidities (25 with BMI > 30, 15 current smokers, 12 with diabetes). A total of 42 PCF (93%) and 23 ACDF (74%) participants had cervical myelopathy. The mean number of levels operated was 4.1 for PCF (range 1 to 7) and 1.5 for ACDF (range 1 to 2). Of the 30 PCF participants with data available, 86.7% were either fully (n = 21) or partially (n = 5) fused at 12 months. Additionally, 96.0% of the 124 PCF segments were either fully (n = 114) or partially (n = 5) fused. Of the 21 ACDF participants, 100% were either fully (n = 15) or partially (n = 6) fused at 12 months. Additionally, 100% of the 31 ACDF segments were either fully (n = 25) or partially (n = 6) fused. Mean improvement at 12 months for ACDF was noted in NDI (p = 0.004), SF-12 mental score (p = 0.010), NRS arm score (p = 0.031), and NRS neck score (p < 0.001). Mean improvement at 12 months for PCF was noted in NDI (p < 0.001), SF-12 physical score (p = 0.008), NRS arm score (p = 0.009), NRS neck score (p < 0.001) and mJOA (p < 0.001). No adverse events were reported that were related to the device. Conclusions: High fusion rates at 12-months in cervical interbody and posterior spinal arthrodesis were observed with P-15 peptide enhanced bone graft. Approximately 3 out of 4 of the patient population was considered high risk presenting with at least 1 co-morbidity known to adversely impact fusion and clinical outcomes. There was no evidence of graft related complications and no index level re-operations at 1-year post-operative.

OP27: Diagnostics and Modalities

ID: 2590

A235: Creating a prospective multicenter international study on intra-operative neuromonitoring in spinal deformity surgery

Stephen Lewis ¹ , Ariel Zohar ¹ , Lawrence Lenke ²

¹ University of Toronto, Toronto, Canada,

² Columbia University, New York, United States

Introduction: Significant controversy exists in the understanding, interpretation and methods used in Intra-operative Neuromonitoring (IONM) during complex spinal deformity surgeries. While there are multiple studies on IONM, the majority are retrospective, lump all types of changes together, and do not provide a detailed association of the events leading to the alert, the actions taken in response to the alert and the neurological sequelae. We review the methods of a prospective multicenter study on IONM using custom standardized forms in obtaining the necessary information to improve the understanding and interpreting IONM changes in spinal deformity surgery. Material and Methods: 20 centers with established IONM programs performing pediatric and/or adult spinal deformity surgeries were recruited. A standardized neuromonitoring protocol using transcranial MEP, SSEP and free run EMG under total intravenous anesthesia was communicated to all centers through multiple video conference calls. A custom standardized form was completed by each center incorporating demographics, radiographic features and measurements, procedural data, pre/post-operative neurological examination and details of IONM modalities and muscle and sensory regions recorded. For each IONM alert, detailed information in real-time on the time, hemoglobin and blood pressure at the time of the alert, which modalities were affected, which muscle groups or sensory regions were involved, the events preceding the alert, the actions taken in response to the alert, and details of the recovery of the IONM signal. Results: 555 patients from 20 centers were collected. Compliance in the form completion for demographic, surgical and radiographic detail was > 99% in all categories except pre-operative Cobb angle (92.3%) and baseline Hb level (97.3%). Completion of the neurological examination pre-op, immediate post-op and at discharge was > 99% in all categories except for pin prick examination which was 97.7%. There were 117 alerts in this cohort. The cause of the alert was surgical in 76%, systemic in 6%, anesthesia related in 12% and technical from the leads in 15%. 89.7% of alerts involved a loss in MEP signal, 17.9% involved a loss in SSEP signal and 13.7 % included a train of EMG activity > 10seconds. A systemic intervention (ie. Raise BP, transfuse) was performed in 51.3%, a surgical maneuver in 43.6%, and a technical correction in 6%. IONM signal returned to baseline in 70.1% of alerts and did not recover to baseline in 15.4%. New neurological deficits occurred in 28.2% of cases with 19.7% of the deficits still present upon discharge from hospital. Compliance for completing the form when an alert occurred was > 95% in all components of the form except for data collected for hemoglobin at time of alert (61.5%) and measurement of the diastolic blood pressure (94%) and mean arterial pressure (94%). 13 patients underwent a wake-up test. Conclusion: The methods employed and custom standardized IONM forms created for this study were effective in collecting valuable real-time data that will allow for high level interpretation and understandings of IONM changes. This information will significantly influence the understanding and help to create algorithms for IONM changes that will greatly help surgical teams appropriately manage these stressful situations.

ID: 2903

A236

A multi-modal artificial intelligence algorithm for the identification of syndromic scoliosis among broader scoliosis population

Nan Wu ¹ , Guilin Chen ¹ , Ziquan Li ¹ , Jianguo Zhang ¹

¹ Peking Union Medical College, Beijing, China

Introduction: Scoliosis is a spinal deformity defined by a Cobb angle exceeding 10 degrees. Etiologically, scoliosis is classified into congenital, syndromic, neuromuscular, and idiopathic scoliosis. Diagnosing scoliosis, particularly syndromic scoliosis, poses significant challenges for clinicians. Syndromic scoliosis diagnosis frequently necessitates whole-exome or whole-genome sequencing, followed by a comprehensive interpretation by experienced spinal surgeons and geneticists to establish a definitive diagnosis. A significant challenge is accurately identifying high-risk syndromic scoliosis patients among the broader scoliosis population. To address this, we have developed an AI model that leverages patients' EHR (electronic health records) data and full-spine anteroposterior and lateral imaging to classify scoliosis subtypes. This model aims to facilitate both diagnosis and treatment for scoliosis patients. Material and Methods: We developed the AI module using 4,872 electronic health records (EHRs) and 18,339 full-spine anteroposterior and lateral standing radiographs collected from a single center (Peking Union Medical College Hospital) and under the framework of DISCO (Deciphering Disorders Involving Scoliosis & COmorbidities) study. Each patient was diagnosed with congenital, syndromic, neuromuscular, or idiopathic scoliosis by at least two spine experts. Genetic tests conducted as part of the DISCO study confirmed all syndromic scoliosis diagnoses. The model was developed using the Prefix Image-text Transformer with ChatGLM and BEiT frameworks. Results: The dataset was divided into a training set of 432 cases containing 108 cases of each category of scoliosis and a validation set of 1,341 cases. Our cohort included 760 idiopathic scoliosis, 711 congenital scoliosis, 167 syndromic scoliosis, and 135 neuromuscular scoliosis cases. The accuracy of the multi-module model in diagnosing congenital scoliosis, syndromic scoliosis, neuromuscular scoliosis, and idiopathic scoliosis was 0.80, 1.00, 0.78, and 0.80, respectively. The F1 scores for the model's performance in diagnosing congenital, syndromic, neuromuscular, and idiopathic scoliosis were 0.70, 0.92, 0.69, and 0.73, respectively. Conclusion: Our model can accurately identify the syndromic scoliosis among the broader scoliosis population. Thus, the genetic test can be used to confirm the diagnosis, which makes the diagnosis more accessible and more accurate.

ID: 2278

A237: Validation of the AO Spine Osteoporotic Fracture Classification: influence of geographic region on reliability and reproducibility

Sebastian Bigdon ^1,2 , Julian Scherer ³ , Gaston Camino-Willhuber ⁴ , Ulrich Spiegl ⁵ , Andrei Joaquim ⁶ , Harvinder Singh Chhabra ⁷ , Gregory Schroeder ⁸ , Marcel F. Dvorak ⁹ , Mohammad El-Sharkawi ¹⁰ , Richard Bransford ¹¹ , Lorin Benneker ¹ , Klaus Schnake ¹²

¹ Department for Spine Surgery, Sonnenhof Spital, University of Bern, Bern, Switzerland,

² Department for orthopaedics and traumatology, Inselspital, University Hospital Bern, Bern, Switzerland,

³ Division of Orthopaedic Surgery, Faculty of Health Sciences, University of Cape Town, Cape Town, Kapetown, South Africa,

⁴ Policina Gipuzkoa, San Sebastian, Spain,

⁵ Klinik für Unfallchirurgie und Orthopädie, Klinik München Harlaching, München, Germany, ⁶ Neurosurgery Division, Department of Neurology, State University of Campinas, Sao Paulo, Brazil,

⁷ Sri Balaji Action Medical Institute, New Delhi, India,

⁸ epartment of Orthopaedic Surgery, Rothman Institute, Thomas Jefferson University Hospital, Philadelphia, United States,

⁹ Combined Neurosurgical and Orthopedic Spine Program, Vancouver General Hospital, University of British Columbia, Vancouver, Canada,

¹⁰ Department of Orthopaedic and Trauma Surgery, Faculty of Medicine, Assiut University, Assiut, Egypt,

¹¹ Department of Orthopaedics and Sports Medicine, Harborview Medical Center, University of Washington, Seattle, United States,

¹² Center for Spinal and Scoliosis Surgery, Malteser Waldkrankenhaus St. Marien Erlangen, Erlangen, Germany

Background: Osteoporotic vertebral fractures are a growing global health concern, with increasing incidence rates necessitating standardized classification systems for effective diagnosis, treatment, and communication among clinicians. The AO Spine-DGOU Osteoporotic Fracture Classification System was introduced in 2018 to categorize osteoporotic thoracolumbar vertebral body fractures into five types (OF 1-OF 5), aiming to guide therapeutic decisions and improve patient outcomes. While previous smaller studies have shown reliability and reproducibility of this system, larger-scale validation considering geographic influences is essential. Purpose: To evaluate the impact of geographic region on the reliability and reproducibility of the AO Spine-DGOU Osteoporotic Fracture Classification System among international clinicians. Methods: A total of 320 participants from six global regions (Europe, Asia, Central/South America, Africa, North America, and the Middle East) were recruited for this study. Participants underwent training via an online webinar and were provided with official classification materials. Each participant classified 27 cases of osteoporotic vertebral fractures using standardized imaging in two rounds, four weeks apart, to assess intraobserver reproducibility. Interobserver reliability and intraobserver reproducibility were calculated using Fleiss' kappa coefficients (κ). Agreement with a gold-standard committee was also evaluated. Results: Globally, the classification system demonstrated moderate to substantial agreement with the gold standard, with κ values improving from 0.58 in the first assessment to 0.61 in the second. European participants exhibited the highest agreement levels (κ = 0.64 and κ = 0.66), achieving substantial agreement in both assessments. OF 4 fractures were most accurately classified across all regions, while OF 3 fractures showed the least agreement. Intraobserver reproducibility was highest among European participants, with significant differences compared to other regions (p = 0.017). Post-hoc analysis revealed that German-speaking participants had significantly better reliability than other European participants (κ = 0.79 vs. κ = 0.70, p = 0.0026). Conclusion: The AO Spine-DGOU Osteoporotic Fracture Classification System shows moderate to substantial reliability and reproducibility internationally, with notable regional variations. European clinicians, particularly those from German-speaking countries, demonstrated higher agreement levels, potentially due to differences in training, clinical experience, and familiarity with the classification system. These findings highlight the necessity of targeted education and standardized training protocols to enhance the global clinical utility of the classification. Significance: This study underscores the influence of geographic and cultural factors on the adoption and application of fracture classification systems. Addressing regional disparities through tailored educational initiatives is crucial for improving consistency in the assessment and management of osteoporotic vertebral fractures worldwide, ultimately enhancing patient care.

ID: 2383

A238: Evaluation of deep learning algorithmic models to detect cervical ossification of posterior longitudinal ligament: systematic review and meta-analysis

Ali Haider Bangash ¹ , Mohammed Q. Alibraheemi ² , Rose Fluss ^1,3 , Sertac Kirnaz ³ , Saikiran Murthy ³ , Yaroslav Gelfand ³ , Reza Yassari ³ , Rafael De La Garza Ramos ^1,3

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

² Faculty of Medicine, Carol Davila University of Medicine, Bucharest, Romania,

³ Department of Neurosurgery, Montefiore Medical Center, Albert Einstein College of Medicine, Bronx, NY, United States

Introduction: Cervical ossification of the posterior longitudinal ligament (c-OPLL) is a challenging condition that requires accurate diagnosis for effective management. However, low-resource settings may not have access to advanced imaging and specialists. However, Deep learning (DL) algorithms have shown promise in medical imaging analysis, comparable to the performance of board-certified specialists. This systematic review and meta-analysis aimed to evaluate the performance of DL algorithmic models in detecting cervical OPLL on various imaging modalities, especially radiographs, with a focus on exploring their potential to be integrated into clinical practice. Material and Methods: Following PRISMA guidelines, we systematically searched PubMed/Medline, Cochrane Database, and Epistemonikos for studies adopting DL algorithms to detect c-OPLL on imaging modalities. Inclusion criteria encompassed studies with cervical OPLL patients, DL algorithms, separate training and testing datasets, and ground truths determined by specified medical professionals. The Quality Assessment of Diagnostic Accuracy Studies – version 2 (QUADAS-2) tool was adopted to assess study quality and risk of bias (RoB). Performance metrics (AUC, sensitivity, specificity, likelihood ratios, predictive values, and Cohen's Kappa) were extracted or calculated. Meta-analysis used random-effects Generic Inverse Variance models. Heterogeneity was assessed using I² statistic, and publication bias was evaluated using Egger's and Begg's tests. Results: Out of a total of 14 studies, 6 studies met inclusion criteria, encompassing 3,729 patients (mean age 56 ± 12.28 years, 43% female). All included studies were retrospective in design. Plain radiography was the data input imaging modality in 83% (n = 5) studies, with convolutional neural networks architecture adopted in 67% (n = 4) studies. The QUADAS-2 assessment indicated all included studies to have a low RoB in the ‘Reference Standard’ domain and its related applicability, with 17% (n = 1) studies each exhibiting uncertainty in patient selection and index test domains. Meta-analysis revealed high performance of DL algorithms for c-OPLL detection using radiographic imaging data: AUC of 0.93 (95% CI: 0.87-0.99), sensitivity of 90.57% (95% CI: 84.67-96.46), specificity of 88.68% (95% CI: 78.38-98.97), positive likelihood ratio of 13.38 (95% CI: -3.59-30.35), negative likelihood ratio of 0.16 (95% CI: 0.04-0.28), positive predictive value of 87.22% (95% CI: 83.35-91.09), negative predictive value of 89.52% (95% CI: 86.09-92.95), accuracy of 88.54% (95% CI: 85.69-91.38), and Cohen's Kappa (vs. spine surgeons) of 0.76 (95% CI: 0.71-0.82). Significant heterogeneity (I² > 75%) and publication bias was observed for most metrics. Conclusion: This systematic review demonstrated that DL algorithmic models exhibit high performance in detecting c-OPLL across various imaging modalities, particularly radiographs. The performance of models was comparable to that of board-certified spine surgeons, suggesting potential for clinical integration. However, the high heterogeneity and detected publication bias warrant cautious interpretation. Future prospective, multi-center studies with larger, diverse patient cohorts are required to validate these findings and assess the models' generalizability. Additionally, research should focus on standardizing DL model development and reporting to enhance comparability across studies. While promising, further investigation is required before these DL models can be confidently incorporated into routine clinical practice for c-OPLL detection.

ID: 1139

A239: Nearly one out of five spondylolysis are missed by MRI reports in pediatric patients with low back pain

George Michael ¹ , Andy Liu ¹ , Suhas Etigunta ¹ , David Skaggs ¹ , Vivien Chan ¹ , Kenneth Illingworth ¹

¹ Cedars-Sinai Medical Center, Pediatric Spine/Orthopaedics, Los Angeles, United States

Introduction: Spondylolysis, a defect in the pars interarticularis, is a common cause of pediatric back pain, particularly in athletes who compete in sports that require hyperextension of the lumbar spine. Computed tomography (CT) is the best test for confirming the diagnosis, however its widespread use is limited secondary to radiation exposure. Magnetic Resonance imaging (MRI) is more commonly used as a frontline imaging modality to evaluate patients with persistent low back pain. Previous studies have noted that spondylolysis is frequently missed on MRI; however, these studies have been limited due to the small number of patients. The aim of this study was to evaluate the rate of missed diagnosis of spondylolysis on MRI with a larger patient cohort and find any potential trends. Methods: A retrospective review was done of all patients seen at a single quaternary care center from January 2021- July 2024 by two pediatric spine surgeons. Inclusion criteria was a confirmed diagnosis of spondylolysis by either CT or provider interpretation of the MRI based on edema within the pars interarticularis on MRI STIR sequences. Patients with spondylolisthesis were excluded (n=77). All imaging collected was interpreted by one of the two pediatric spine surgeons as part of their standard clinical practice. Patient demographics were collected with an additional recording of the main mechanism of reproducing pain and pain during athletic activity. Official radiology reads were collected and compared to the surgeon’s interpretation. In addition, radiology reads were analyzed based on the location of the imaging center (i.e., hospital vs private imaging center), qualifications of the radiologist (i.e., fellowship training), and the incidence of surgeon-radiologist agreement on the report. Results: 86 patients with an average age of 14.9 years old (range 11-27) met inclusion criteria. Of those 86 patients, 17 (19.8 %) had an official MRI radiology report that had missed the spondylolysis. Of those 17 patients with missed MRIs, 70.6% (n = 12) of the radiology reads came from private imaging centers. In addition, 12 of the 17 missed MRIs came from radiologists who had no formal fellowship training in either musculoskeletal or neuroradiology. Lower back pain with extension was a physical exam finding in 78 patients (90.70%), and 80 patients (93%) were limited in their athletic activities secondary to their pain. Conclusion: MRI radiology reads had missed a spondylolysis in nearly one out of five patients. Although improved from previous studies, one must still have a high index of suspicion in adolescent patients with low back pain, specifically low back pain with lumbar hyperextension. Edema within the pedicle/pars interarticularis on sagittal STIR images is pathognomonic for spondylolysis.

ID: 201

A240: Comparison of predictive performance for proximal junctional kyphosis between CT-based Hounsfield units and MRI-based vertebral bone quality score in adult degenerative scoliosis

Honghao Yang ¹ , Yong Hai ¹

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

Introduction: To compare the predictive performance between CT-based Hounsfield units (HU) and MRI-based vertebral bone quality (VBQ) for proximal junctional kyphosis (PJK) in adult degenerative scoliosis (ADS). Material and Methods: This is a retrospective study of ADS patients treated at our institution from 2014 to 2023. Proximal junctional kyphosis (PJK) was assessed via X-ray, defined as a change of ≥ 10 degrees in the Cobb angle between UIV+2 and UIV compared to preoperative measurements. VBQ scores and HU values were measured from preoperative MRI and CT scans, respectively. Subsequently, the predictive performance of these two parameters were evaluated by comparing receiver operating characteristic (ROC) curves using the DeLong test. Results: A total of 164 patients (mean age 68.2 years) were included in the study, and 26 (15.9%) developed PJK. Patients who developed PJK had significantly higher VBQ scores (3.06 ± 0.57 vs. 2.45 ± 0.46, p < 0.001) and significantly lower HU values (105.91 ± 26.54 vs. 140.15 ± 47.27, p < 0.001). Both VBQ scores and HU values could predict the occurrence of PJK, with no significant difference in predictive ability between the two (p = 0.3867). There was a significant difference in postoperative spinal sagittal vertical axis (SVA) between the PJK group and the non-PJK group (45.3 ± 18.5 mm vs. 37.0 ± 14.8 mm, p = 0.013). Conclusion: MRI-based VBQ scores and CT-based HU values can both accurately predict the occurrence of PJK in patients with ADS, with no significant difference in predictive performance between the two. MRI-based VBQ score could be an alternative to conventional HU values.

ID: 2832

A241: Unilateral intra-operative neuromonitoring (IONM) MEP alerts in cord level surgeries for severe spinal deformity-etiology and recovery patterns

Colby Oitment ¹ , Saumyajit Basu ² , Stephen Lewis ¹

¹ University of Toronto, Toronto, Canada,

² Kothari Medical Centre, Kolkata, India

Introduction: IONM alerts are commonly encountered in corrective surgeries for severe spinal deformities. The purpose of this study was to identify the causes and significance of unilateral alerts in complex spinal deformity surgery. Material and Methods: A prospective, multicentric cohort study in 20 international centers documented the demographics, radiographic findings, and surgical events of patients undergoing complex spinal deformity correction surgery with EMG, SSEP, and MEP monitoring. A standardized data collection form included details of all IONM alerts, including events preceding alerts and corrective measures taken. Detailed neurological examination was performed at baseline, immediately post-op, and before discharge from hospital. IONM alert was defined as a loss of amplitude of > 50% from baseline in SSEP or MEP or sustained EMG activity lasting > 10 seconds. Results: 349 out of 555 patients had cord-level surgeries for severe spinal deformities. 57 patients had IONM alerts with 44 unilateral MEP alerts occurring in 37 patients. The average age was 21.4 (± 15.6) years, and 70.3% were female. 75.7% had scoliosis with a mean coronal Cobb angle of 77.6 ⁰ (± 24.8⁰) and coronal DAR (deformity angular ratio) was 11.5 (± 3.6). All had deformity apex in the thoracic spine with T9 (24.3%) and T8 (21.6%) the commonest levels. Intraoperative traction was utilized in 29.7%. 34 patients (91.9%) had an osteotomy, with 9 having 3-column osteotomies. 44 alerts occurred in these 37 patients, of which 38 had isolated MEP alerts, and 6 had combined with SSEP. The mean time of unilateral alert from skin incision was 213.8 minutes. Of the 44 events preceding the alerts, implant placement was seen in 7 (18.4%), osteotomy/release in 22 (57.9%), rod placement in 8 (21.1%), traction in 2 (5.3%) and other in 2 (5.3%). Common responses to alert were elevating blood pressure (36.4%), transfusing blood (20.5%), implant removal (18.2%), and steroids (18.2%). A traumatic surgical event was identified in 27 (61.4%) unilateral MEP alerts. Complete unilateral MEP signal loss occurred in 22.7%, > 75% loss in 68.2% and > 50% loss in 9.1%. By skin closure, MEP signal recovered to near baseline in 68.2% with 81.8% of alerts recovering to at least 50% of baseline. Of the 37 patients that had unilateral MEP losses, de novo neurological deficits were seen immediately post-op in 10 (27%) with 1 patient suffering a spinal cord syndrome. At discharge from hospital, 4 (10.8%) had neurological deficits. Conclusion: This study demonstrates that unilateral MEP alerts with and without SSEP changes will occur most frequently with osteotomies. 27% of patients with unilateral MEP alerts had early neurological deficits, with deficits at discharge being reduced to 10.8% of the patients. Appropriate surgical maneuvres relieving any compressive pathology was associated with partial or complete reversal of the IONM signal loss. 70% of complete unilateral MEP alerts resolved to near baseline within 60 minutes of the causative event and 82.1% of the incomplete losses recovered to at least 50% of baseline by skin closure. Recognizing and responding to unilateral MEP alerts was associated with a good outcome in this cohort of patients undergoing complex spinal deformity surgery.

ID: 988

A242: Development of a model combining deep convolutional neural networks based on MRI with clinical data for differentiation of tuberculous spondylitis and pyogenic spondylitis

Wei Xiong ¹ , Feng Li ¹

¹ Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China

Introduction: Accurate and expeditious discrimination between Pyogenic spondylitis (PS) and Tuberculous spondylitis (TS) of the spinal column is paramount, as it directly correlates with the clinical outcomes and subsequent patient management strategies. Within the domain of medical diagnostics, the integration of Deep Convolutional Neural Networks (DCNNs) into imaging analysis is rapidly advancing, promising a transformative leap in the precision and efficacy of diagnostic procedures. Material and Methods: This study included 236 patients with infectious spondylitis, including PS and TS. A total of 2296 sagittal and 3426 axial STIR magnetic resonance images with 236 clinical data from patients were acquired and used for CNN training and validation. In this study, we meticulously delineated receiver operating characteristic (ROC) curves for the models based on sagittal and axial imaging and the amalgamation of clinical data. The area under the curve (AUC) was meticulously computed to quantitatively gauge the DCNN performance metrics. Subsequently, we compared the sensitivity, specificity, and diagnostic accuracy of the sagittal and axial image models against the assessments provided by a panel of three experienced radiologists, ensuring a robust evaluation of the model's clinical utility and diagnostic efficacy. Finally, we conducted a comparative analysis of the diagnostic efficacy between the DCNN model utilizing solely clinical data and the hybrid DCNN model that incorporates both clinical data and imaging data. The hybrid model integrates sagittal and axial DCNN modelling alongside clinical data. The DCNN architecture uses stacked residual blocks to extract features indicative of spondylitis from both sagittal and axial images. These features are combined with clinical data to develop a multifactorial regression model. Results: The highest AUCs for the sagittal image model, the axial image model, the sagittal + axial image model, and the hybrid model with images and clinical data were 0.886 (95% CI 0.866,0.906), 0.853 (95% CI 0.831,0.875), and 0.984 (95% CI 0.957,1.000), respectively. The sagittal + axial image model has an equal efficacy comparable to a professional musculoskeletal radiologist with 15 years of experience. The overall efficacy of the DCNN model combined with clinical data was higher than that of the model constructed with clinical data only. Conclusion: In conclusion, the integration of the hybrid DCNN model by the retrospective study has proven to be a significant catalyst for enhancing diagnostic accuracy in the realm of infectious spondylitis, encompassing both pyogenic spondylodiscitis and tuberculous spondylitis with improved precision and timely diagnostic decisions.

ID: 183

A243: Advancing the early detection of degenerative cervical myelopathy: a systematic review of screening methods for the primary care setting

Sean Inzerillo ¹ , Pemla Jagtiani ¹ , Salazar Jones ²

¹ State University of New York Downstate Health Sciences University, Brooklyn, United States,

² Mount Sinai Hospital, Neurological Surgery, New York, United States

Introduction: Early diagnosis of degenerative cervical myelopathy (DCM) is often challenging due to subtle, non-specific symptoms, limited disease awareness, and a lack of definitive diagnostic criteria. As primary care physicians are typically the first to encounter patients with early DCM, equipping them with effective screening tools is crucial for reducing diagnostic delays and improving patient outcomes. This systematic review evaluates the efficacy of quantitative screening methods for DCM that can be implemented in the primary care setting. Material and Methods: A systematic search following PRISMA guidelines was conducted across PubMed, Embase, and Cochrane Library up to July 2024. Search terms included “degenerative cervical myelopathy,” “cervical myelopathy,” “screening,” “physical exam,” “clinical assessment,” and “questionnaires.” Studies were included if they evaluated screening tools for DCM applicable to primary care settings and reported sensitivity and specificity diagnostic accuracy measures. Conference abstracts, reviews, meta-analyses, non-English studies, and those focusing solely on asymptomatic spinal cord compression or screening tools irrelevant to primary care were excluded. Two independent researchers reviewed the studies, extracted data, and assessed study quality using the QUADAS-2 tool. The Youden Index, defined as sensitivity plus specificity minus one, was used to assess diagnostic balance, with values of 0.60 or higher indicating an effective diagnostic method. Results: The search identified 14 studies evaluating 18 DCM screening methods in a total of 6478 subjects. These studies were published between 2010 and 2024 and employed case-control designs, with all but two being prospective. While the QUADAS-2 tool identified a potential risk of bias in patient selection due to the case-control nature of the studies, applicability concerns and other measures of bias were generally low. Screening tools were categorized into three groups: questionnaires, conventional physical performance tests (PPTs), and sensor-assisted PPTs. Both identified questionnaires consistently showed high diagnostic accuracy, with Youden Indices exceeding 0.60. In contrast, only three out of nine conventional PPTs met the same threshold. Sensor-assisted physical performance tests (PPTs), which use specialized sensors to precisely measure movement, demonstrated significant diagnostic accuracy, with five out of seven methods achieving Youden Indices above 0.60. The highest value (0.841) was reported by employing a finger-wearable gyro sensor during the 10-second grip and release test. However, these tools present challenges related to accessibility and learning curves. Conclusion: This review highlights the potential of quantitative screening methods for early DCM detection in primary care. While questionnaires and conventional tests are accessible and effective, sensor-assisted tests offer superior accuracy but face challenges in implementation. A multi-faceted approach, tailored to primary care resources, is essential for improving patient outcomes. Future research should focus on validating these methods across diverse populations and standardizing diagnostic criteria.

OP28: Medical Economics and Cost Effectiveness

ID: 1749

A244: A comparative analysis study of cost-effectiveness among open transforaminal lumbar interbody fusion, minimally invasive transforaminal lumbar interbody fusion (MIS TLIF), and oblique lateral lumbar interbody fusion (OLIF)

Panapol Varakornpipat ¹

¹ Department of Orthopedic, Faculty of Medicine, Naresuan University, Phitsanulok, Thailand

Introduction: Lumbar spinal fusion has emerged as a standard surgical procedure for addressing degenerative pathologies. Minimally invasive surgery with lumbar interbody fusion has proven to be an effective alternative, offering sufficient visualization and enabling the attainment of surgical objectives. However, the material cost associated with MIS TLIF and OLIF is notably high, especially in developing countries. Consequently, the cost-effectiveness of single-level MIS TLIF, OLIF, and open TLIF remains unclear in such settings. This study aims to compare the cost-utility and clinical outcomes of MIS TLIF, OLIF, and open TLIF specifically in Thailand. Material and Methods: Patients with lumbar spinal stenosis who underwent single-level open TLIF, MIS-TLIF, and OLIF between 2015 and 2022 were retrospectively reviewed. Preoperative, 1-month, 3-month, 6-month, and 1-year follow-up clinical outcomes including EQ-5D and VAS scores, as well as healthcare costs, were collected. The results were evaluated based on quality-adjusted life years (QALYs) and incremental cost-effectiveness ratios (ICERs). Results: The study enrolled 236 patients, with 79 undergoing OLIF, 79 undergoing MIS TLIF, and 79 undergoing open TLIF. The mean total costs of open, MIS TLIF, and OLIF were 3,910.18 ± 1,242.12 USD, 5,396.37 ± 1,436.41 USD, and 5,854.93 ± 1,108.60 USD, respectively (p < 0.001). There was a significantly higher implant cost in the OLIF group: 2,938.86 ± 564.18 USD (p < 0.001), including cages (1,087.31 ± 0), percutaneous pedicular screws (1,243.87 ± 355.01), and biologic bone grafts (543.66 ± 0) (p < 0.001). The clinical VAS back score of the MIS TLIF and OLIF groups significantly improved at 1 month compared to open TLIF, but the improvement was not significant at 3, 6 months, and 1 year. The open TLIF group showed greater estimated blood loss (522.69 ± 87.8 ml), longer operative time (3.85 ± 0.58 hours), and longer hospital stays (4.88 ± 0.64 days) (p < 0.001). At 1 and 3 months postoperatively, the EQ-5D scores of the MIS TLIF and OLIF groups improved significantly compared to open TLIF, but the improvement was not significant at 6 months and 1 year. The MIS TLIF and OLIF groups had significantly better utility scores than the open TLIF group. The mean QALYs gained in 1 year showed no significant difference among the three procedures but at 1 month, the QALYs gains of OLIF (0.992) were significantly greater compared to MIS TLIF (0.901) and open TLIF (0.681). Conclusion: OLIF and MIS TLIF significantly reduce pain and disability in short term clinical outcomes compared open TLIF, but economic evaluation found that open TLIF is cost saving than MIS TLIF and OLIF.

ID: 1744

A245: Socioeconomic disparities in postoperative opioid use following spine surgery: a retrospective analysis of area deprivation Index and Household income

Ahmad Kareem Almekkawi ¹ , Ashlesha Bohjane ² , Abigail Jenkins ³ , James P. Caruso ⁴ , Salah Aoun ⁵ , Carlos Bagley ¹

¹ Saint Luke's Hospital, Neurosurgery, Kansas City, United States,

² University of Missouri-Kansas City School of Medicine, Kansas City, United States,

³ UT Southwestern, School of Medicine, Dallas, United States,

⁴ NYU Langone, Orthopedic Surgery, New York, United States,

⁵ UT Southwestern, Neurosurgery, Dallas, United States

Introduction: The opioid epidemic has heightened scrutiny of postoperative opioid prescribing, particularly in spine surgery. This study investigates the relationship between socioeconomic factors and opioid prescriptions following spine surgery. Material and Methods: A retrospective analysis was conducted on 1,132 patients who underwent spine surgery between August 2015 and August 2023. Socioeconomic status was assessed using Area Deprivation Index (ADI) and household income. Chi-square tests, t-tests, and Tukey's HSD post-hoc analyses were performed to evaluate associations between socioeconomic factors and opioid prescriptions at 3 and 12 months postoperatively. Results: Significant associations were found between 3-month opioid prescriptions and both race (p = 0.005545) and income groups (p = 0.019774). Patients in lower income brackets were more likely to have 3-month opioid prescriptions compared to higher income groups. However, these associations were not significant at 12 months, except between the lowest and highest income groups (p = 0.0472). ADI showed a weak positive correlation with 3-month prescriptions (r = 0.0625) and a weak negative correlation with 12-month prescriptions (r = -0.0098). Conclusion: Socioeconomic factors, particularly household income, influence short-term postoperative opioid use following spine surgery, but their impact on long-term use is less pronounced. These findings highlight the need for targeted interventions in the early postoperative period and comprehensive, individualized approaches to long-term pain management that address the complex interplay of socioeconomic and clinical factors.

ID: 2558

A246: The economic costs of spine fracture hospitalization in Poland - a single centre analysis

Michal Krakowiak ¹ , Jarosław Dzierżanowski ¹ , Klaudia Kokot ² , Rami Yuser ² , Piotr Zieliński ²

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

² Students’ Scientific Circle of Neurosurgery, Neurosurgery, Gdansk, Poland

Introduction: Spine fractures represent a minor part of trauma patients but their influence on the patients’ social and financial environment is more significant than other injuries. They have large socioeconomic consequences. Most fractures occur in the thoracic and lumbar spine followed by the cervical region. The aim of this study is to present an economic hospitalization cost comparison generated by spine fractures at different regions. Material and Methods: The study includes a retrospective analysis of spine fracture patients who were admitted to the Department of Neurosurgery at the University Clinical Center in Gdansk from 01.2020 up to 07.2024. Data was gathered on the basis of ICD 10 classification system. Economic data was provided by SGA company by the website MyHospital. Results: 155 fractures were included into the analysis. Cervical spine fractures n = 38 (24.5%), lumbar fractures n = 51 (32.9%), thoracic n = 66 (42.6%). The mean age of patient was 47 years. The mean hospital stay was 9 days. The mean hospitalization cost was 30432 PLN. 33 cases (21.6%) generated loss for the Department of which thoracic where the most common n = 16 (48.5%). The mean financial result of cervical, thoracic and lumbar fracture hospitalization was -4303.1 PLN, 11697.8 PLN, 20995.3 PLN respectively. Age was an statistically insignificant factor when compared patients generating loss and not. Conclusion: The results of this economic analysis suggests that cervical spine fractures are the most cost generating of all spine fractures. The most profit is generated from lumbar fracture hospitalization.

ID: 350

A247: Cost-effectiveness analysis of instrumented unilateral posterolateral fusion with transforaminal interbody fusion compared with instrumented bilateral posterolateral fusion in single level lumbar spinal stenosis

Watcharapong Eiamjumras ¹ , Sirichai Wilartratsami ¹ , Panya Luksanapruksa ¹ , Pochamana Phisalprapa ² , Chayanis Kositamongkol ²

¹ Faculty of Medicine Siriraj Hospital, Mahidol University, Orthopaedic Surgery, Bangkok, Thailand,

² Faculty of Medicine Siriraj Hospital, Mahidol University, Medicine, Bangkok, Thailand

Introduction: Lumbar spinal stenosis can lead to disability. Some patients may require surgery, including Posterolateral Fusion (PLF) or Posterolateral Fusion with Transforaminal Lumbar Interbody Fusion (PLF/TLIF). There was no economic study comparing each technique. The aims of this study is to conduct a cost-effectiveness analysis (CEA) and cost-utility analysis (CUA) comparing PLF/TLIF versus PLF for single-level lumbar spinal stenosis (SLS) in Thailand with societal perspective. Materials and Methods: A bidirectional cohort study of SLS patients from 2014 to 2022 compared outcomes, including the Oswestry Disability Index (ODI), EuroQol-5 dimensions 5 levels (EQ-5D-5L), and healthcare costs over 12 months postoperatively. Results were used in an economic model to calculate lifetime costs, quality-adjusted life years (QALYs), incremental cost-effectiveness ratio (ICER), and net monetary benefit (NMB). A Thai willingness-to-pay threshold of 5003 USD per QALY gained and a 3% discount rate were used, with the 2022 exchange rate of 1 USD = 31.98 THB. Results: The study included 140 SLS patients, with 70 underwent PLF/TLIF and 70 underwent PLF. At one year, the PLF/TLIF group showed significantly better ODI scores (22.24 vs. 37.65; p = 0.02) and lower visual analog scores (1.63 vs. 2.34; p = 0.04), but no significant difference in EQ-5D-5L (0.83 vs. 0.84; p = 0.47). The CEA and CUA revealed lifetime costs of 29,248 USD for PLF/TLIF and 35,853 USD for PLF, with QALYs of 12.04 and 11.70, respectively. The NMB was 8,303 USD, with an additional cost of 199 USD for each 1% reduction in ODI. Conclusions: PLF/TLIF demonstrated lower total lifetime costs and better quality of life at one year compared to PLF. Economic evaluation in the Thai context showed PLF/TLIF was cost-effective compared to PLF for SLS.

ID: 552

A248: The economic burden of diabetes in spinal fusion surgery: a systematic review and meta-analysis

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

¹ Institute for Research on Musculoskeletal Disorders, Valencia Catholic University, Valencia, Spain,

² Rush University Medical Center, Chicago, United States,

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 Surgery, Department of Orthopedic Surgery, Philadelphia, United States

Introduction: The cost and value of specific surgical procedures are not uniform across all populations. Diabetes Mellitus (DM) is known to increase spinal surgery patient costs and decrease surgical outcomes. Although studies have evaluated the cost impact of DM in spinal surgery, we performed a meta-analysis controlling for confounding variables to evaluate this on a broader spectrum. This study aimed at comparing the costs of spinal fusion surgery between patients with and without DM. We specifically evaluated cost-impacting events such as length of hospital stay (LOS), reoperation rates, and readmission rates. Material and Methods: Following PRISMA guidelines, a systematic search of four databases, including PubMed, EMBASE, Scopus, and the Cochrane Collaboration Library, was conducted. A meta-analysis was performed on comparative studies examining diabetic versus non-diabetic adults undergoing cervical/lumbar fusion in terms of cost. Heterogeneity was assessed using the I2 test. Standardized mean differences (SMD) and odds ratios (OR) with 95% confidence intervals (CI) were calculated using a random-effects model in the presence of heterogeneity. SMD enable the statistical combination of diverse costs, facilitating a comprehensive assessment of their impact irrespective of the specific cost type. Results: A total of 22 studies were included in this meta-analysis. Standardized costs were significantly higher in the diabetic group (SMD 0.02, 95% CI 0.01 to 0.03, p < 0.05). The excess cost per diabetic patient undergoing spinal fusion surgery was estimated to be $2,492 (95% CI: $1,620 to $3,363). The LOS was significantly longer in the DM (MD 0.42, 95% CI 0.24 to 0.60, p < 0.001). No significant difference was observed in ICU admission between the groups (OR 4.15, 95% CI 0.55 to 31.40, p > 0.05). Reoperation showed no significant differences between the groups (OR 1.14, 95% CI 0.96 to 1.35, p > 0.05). However, 30-day and 90-day readmissions were significantly higher in the DM group: (OR 1.42, 95% CI 1.24 to 1.62, p < 0.05) and (OR 1.39, 95% CI 1.15 to 1.68, p < 0.001), respectively. Non-routine or non-home discharge was also significantly higher in the DM group (OR 1.89, 95% CI 1.67 to 2.13, p < 0.001). Conclusion: This meta-analysis revealed that patients with DM undergoing spinal fusion surgery had increased costs, prolonged LOS, increased 30-day/90-day readmission rates, and more frequent non-routine discharges than patients without DM. These findings emphasize the importance of preoperative optimization and careful postoperative management in patients with DM undergoing spinal surgery.

ID: 1624

A249: Spine surgery utilization in Brazilian Public Healthcare System

Alisson R. Teles ¹

¹ Hospital São José - Santa Casa de Porto Alegre, Porto Alegre, Brazil

Objective: To analyze the socioeconomic, demographic and health management factors associated with spine surgery rates performed by the Brazilian Unified Health System (SUS) in the federative units in Brazil.

Methods: Descriptive and analytical ecologic study was performed on spine surgery rates (per 100,000 inhabitants) performed by SUS, in the 27 federative units of Brazil, between 2014 and 2023. The following variables were analysed: rate of spine surgeries performed (per 100,000 inhabitants), real GDP per capita (in 1,000 Brazilian reais), human development index (HDI), rate of neurosurgeons/orthopedic surgeons who serve SUS (per 100,000 inhabitants), rate of hospitals with neuro/ortho services (per 100,000 inhabitants). Statistical analyses were performed in SPSS. Results: A total of 176,033 spine surgeries were performed during the time period. The mean rate of public spine surgery was 7.32 (sd = 5.29, minimum 0.5 - maximum 26.7, coefficient of variation 72.26%). It was observed a decrease in public spine surgery utilization during 2020-2021. In regional terms, the performance of public spine surgeries in Brazil over the period analyzed suffered a great disparity; the procedures happen mostly in the South and Southeast regions, and least in the North and Northeast regions. Great variability in spine surgery utilization was observed in different federative units, as observed by the coefficient of variability ranging from 69% - 89%. The mean rate of neuro-ortho surgeons who serve SUS was 3.64 (sd 1.52) per 100,000 population. Also, the mean rate of neurosurgery/orthopedic surgery services accredited by SUS was 1.62 (sd 0.91). A positive correlation was identified between spine surgery utilization and rate of surgeons (r2 = 0.024, p = 0.024) and neuro/orthopedic services accredited by SUS (r2 = 0.114, p < 0.001). Moreover, a positive relationship was identified between surgery utilization and GDP per capita (r2 = 0.224, p < 0.001) and HDI (r2 = 0.412, p < 0.001). Final linear regression model identified that rate of surgeons and HDI was independently associated with higher utilization rate of spine surgery in public healthcare system in Brazil. Conclusion: Spine surgery utilization rate in Brazil presented high variation across different federative units. Surgeon’s availability and economic development were associated with higher utilization rates.

ID: 1033

A250: An updated cost analysis of magnetically controlled growing rods (MCGR) for early onset scoliosis following new manufacturer recommendations

Adam Lloyd ¹ , Jayesh Trivedi ¹ , Neil Davidson ¹ , Sudarshan Munigangaiah ¹

¹ The Robert Jones and Agnes Hunt Hospital NHS Foundation Trust, Oswestry, United Kingdom

Introduction: In 2009, magnetically controlled growing rods (MCGR) gained approval for use within the European Economic Area as a treatment option for early onset scoliosis (EOS). A 2014 NICE medical technology guideline (MTG 18) reported the device to be a cost-effective surgical option, but reports of early device related complications led to voluntary withdrawal from the UK market in 2020. New manufacturer recommendations for implant removal 2 years post implantation have since been published and the device has again become available for use. However, the cost implications of these new recommendations have not yet been evaluated. Material and Methods: This was an updated analysis based on previously published data that formed a basis for the MTG 18 guidelines in 2014. MCGR costs were modelled against those incurred using conventional growing rods for up to six years from index surgery assuming a requirement for both types of implant to be exchanged every 2 years and an annual device failure rate of 4.5%. Costs related to inpatient and outpatient care were included as per the original published analysis. Results: This analysis revealed that at the two-, four- and six-year timepoints, use of MGCR resulted in increased costs compared with conventional growing rods. Cumulative costs were £7582 greater at two years, £8586 more at four years and £9627 greater at six years; however none of these differences were statistically significant. Conclusion: In contrast to the previously published cost analysis in MTG 18 which evaluated MCGR to be cost neutral at 35 months following implantation, this updated analysis accounting for new device recommendations has found total costs of use to be greater at all time points in comparison to those incurred using conventional growing rods. This should be considered by surgeons in an increasingly economically challenged health services.

ID: 1236

A251: Inpatient costs for spine-related conditions in Brazilian Healthcare System (SUS) between 2014 and 2023

Carlos Tucci ^1,2 , Ari Halpern ^1,3 , Gabriely Rangel ¹ , Marina Siqueira ¹ , Marilia Navarro ¹ , Lucas Correa ¹

¹ Hospital Israelita Albert Einstein, CEPPS - Centro de Estudos e Promoção de Políticas em Saúde, São Paulo, Brazil,

² Sociedade Brasileira de Coluna, Comissão de Políticas em Saúde, São Paulo, Brazil,

³ HCFMUSP, Reumatologia, São Paulo, Brazil

Introduction: Spine-related conditions (SRC) are increasingly prevalent and pose a major challenge to the universal Brazilian healthcare system (SUS) due to their high direct and indirect costs, coupled with a low awareness and absence of specific policies. Spine surgeries are high costs, sometimes unnecessary, financially biased procedures and as such, might have a more effective approach if more reliable data-based policies were available. To date, only a few studies with heterogeneous methodologies have addressed SRC inpatient and outpatient costs within SUS. The aim of this paper is to estimate and evaluate inpatient total and categorized costs in SUS between 2014 and 2023 using a new proposed methodology. Material and Methods: A top-down cost-of-illness study was conducted for the period between 2014 and 2023 using data extracted from SUS hospital database (SIH-SUS). This study concentrated on procedure codes validated by SRC ICD-10, instead of ICD-10 only, aiming to provide a more comprehensive, specific, and standardized approach. All cost data were aggregated, and inflation and currency adjusted to estimate the direct costs of inpatient care for SRC. The analysis encompassed all available inpatient data, which were categorized by: 1) procedure type (surgical, non-surgical, diagnostic*), age groups (0-10, 11-18, 19-64, 65-79, 80-89, > 90), gender, and ethnicity. *Note: Only spine biopsies are considered diagnostic procedures in SUS; imaging exams are conducted at outpatient facilities. Results: Between 2014 and 2023, total direct inpatient costs for spine-related conditions (SRC) in SUS amounted to USD 328,1 million (BRL 1.66 billion). Of this total, USD 301,6 million (BRL 1.53 billion) (91.9%) were attributable to specific SRC surgical procedures, USD 24.5 million (BRL 123.9 million) (7.46%) to non-surgical procedures, and USD 2.0 million (BRL 10.2 million) (0.62%) to diagnostic procedures. The total number of hospital stay days during this period was 2.4 million, with an average of 9 days per procedure. Additionally, 5622 deaths related to SRC procedures were reported. Men had more surgical procedures (61%) than women (39%); 80% of all surgeries were performed in 19-64 age group. Non-white were 49% of all surgical patients. Trends and Impact of COVID-19: From 2014 to 2017, there was a minor reduction in SRC surgical procedures, followed by an upward trend in subsequent years, except for 2020, which experienced a 22% decrease, and 2022, which resulted in a 21% increase. These fluctuations were influenced by the COVID-19 pandemic's impact on overall surgical procedures. Specifically, elective surgical procedures experienced a 43% reduction between 2019 and 2020. Conclusion: The present study concluded that SRC places a high burden in SUS direct costs, predominantly due to surgical procedures. Gender and ethnicity play a significant role. COVID-19 pandemic significantly impacted, as well as population aging, elective SRC surgical procedures. Apart from incidental events like COVID-19, SRC procedures remain a critical focus to policy makers as they represent a high burden in SUS. While the findings suggest that a new methodology may be needed to ensure a more comprehensive, specific, and standardized approach, further investigation in future studies is warranted.

ID: 1591

A252: Outcomes of a 5-year project to improve clinical coding accuracy for paediatric spinal procedures

Conor Boylan ¹ , Duncan Loader ¹ , Morgan Jones ^2,3 , Joe Jan Gouda ²

¹ University of Birmingham, Birmingham, United Kingdom,

² The Royal Orthopaedic Hospital Birmingham, Birmingham, United Kingdom,

³ Birmingham Children's Hospital, Birmingham, United Kingdom

Introduction: All surgical procedures require a rebate (tariff) in order to cover their costs. This must match the actual cost of the procedure plus any other expected expenditure to avoid losses by the hospital. In 2019, paediatric spinal procedures moved from The Royal Orthopaedic Hospital, Birmingham to Birmingham Children's Hospital. Due to clinical coder inexperience, monetary rebates for these procedures fell despite case numbers remaining the same. A long-term quality improvement process was initiated in order to improve coding accuracy at the new institution. Material and Methods: Over three quality improvement cycles, a systematic process of reviewing paediatric spinal procedures and subsequent coding activity was undertaken. Procedures were manually coded and mock rebates generated with the aid of a consultant spinal surgeon and experienced coders from the previous site and compared to actual codes and rebate requests from the new site. Meetings were held with lead coders at the new site and instruction was provided on how to more accurately code spinal procedures. A spinal coding “operation manual” was generated with lay descriptions of spinal procedures and advice on coding them accurately. Results: Quality improvement checkpoints took place in three phases in 2019, 2021 and 2024. The mean difference between optimal and actual rebate requests in phase 1 was £4,243.16 [$5534.69] (SD £12,070.53 [$15,744.56]), in phase 2 was £2560.59 [$3339.98] (SD £10,846.56 [$14,148.04]), and in phase 3 was -£457.42 [-$596.65] (SD £732.32 [$955.22]). This represents a stepwise improvement from 82.16% to 89.91% to 102.47% of the calculated optimal rebate. The change from phase 2 to phase 3 is statistically significant (U = 154.5, z = -2.202, p = 0.026, r = -0.302). Conclusion: This long-term quality improvement process has significantly improved the accuracy of clinical coding for paediatric spinal procedures and, when extrapolated to an average of 150 cases per year, has generated an annual saving of £705,087.00 [$919,701.38] for the site. The authors have learned much from this iterative process and have recommendations that are applicable on a larger scale to any Trust with similar issues that they would like to share at your meeting.

OP29: Thoracolumbar Trauma Surgical

ID: 292

A253: Validation of the AO Spine-DGOU Osteoporotic Fracture Classification - Effect of surgical experience, surgical specialty, work-setting and trauma center level on reliability and reproducibility

Julian Scherer ^1,2 , Sebastian Bigdon ³ , Gaston Camino-Willhuber ⁴ , Ulrich Spiegl ⁵ , Andrei Joaquim ⁶ , Harvinder Singh Chhabra ⁷ , Marcel F. Dvorak ⁸ , Gregory Schroeder ⁹ , Mohammad El-Sharkawi ¹⁰ , Richard Bransford ¹¹ , Lorin Benneker ¹² , Klaus John Schnake ¹³

¹ University of Cape Town, Orthopaedic Research Unit, Division of Orthopaedic Surgery, Cape Town, South Africa,

² University Hospital of Zurich, Zurich, Switzerland,

³ University Hospital Bern, Bern, Switzerland,

⁴ Policina Gipuzkoa, San Sebastian, Spain,

⁵ Klinikum München Harlaching, Munich, Germany,

⁶ State University of Campinas, Sao Paulo, Brazil,

⁷ Sri Balaji Action Medical Institute, New Delhi, India,

⁸ Vancouver General Hospital, Vancouver, Canada,

⁹ Thomas Jefferson University Hospital, Philadelphia, United States,

¹⁰ Assiut University, Assiut, Egypt,

¹¹ University of Washington, Seattle, United States,

¹² University of Bern, Bern, Switzerland,

¹³ Paracelcus Private Medical University, Nuremberg, Germany

Introduction: Osteoporotic vertebral fractures (OVFs) are of increasing concern as they may result in a major morbidity and a potential risk factor for mortality. Treatment algorithms are mainly based on fracture classifications to determine fracture morphology precisely and are necessary for a standardized care of patients. A cornerstone of classification systems is good reliability amongst different groups of classification users. Thus, the aim of this international validation study was to assess the reliability of the new AO Spine-DGOU Osteoporotic Fracture Classification (OF classification) stratified by surgical specialty, work-setting, work-experience, and trauma center level. Material and Methods: 320 spine surgeons participated in this online-webinar based validation process. Participants were asked to rate 27 cases according to the OF classification at two time points, four weeks apart (assessment 1 and 2). The Cohen´s Kappa (κ) statistic was calculated to assess the inter-observer reliability and the intra-rater reproducibility. Members of the Osteoporotic Fracture working group of the DGOU provided the gold standard-classification for each injury on radiological imaging. Results: A total of 7798 (90.3%) ratings were recorded in the first validation round and 6621 (76.6%) ratings were recorded four weeks later. Amongst all participants, the global interrater reliability was moderate in both, first and second assessment (κ = 0.57; κ = 0.58). Participants with a work-experience of more than 20 years showed the highest inter-rater agreement amongst all participations in both assessments globally (κ = 0.65; κ = 0.67). Neurosurgeons had the best global inter-rater agreement in the first assessment (κ = 0.59) whereas orthopaedic spine surgeons showed a higher agreement in assessment two (κ = 0.60). Participants from a level-1 trauma center showed the highest agreement (κ = 0.58), whereas participants working at a tertiary trauma center showed higher grade of agreement in the second assessment (κ = 0.66). Participants working in academia showed the highest agreement in the second assessment (κ = 0.6). Surgeons with academic background and surgeons employed by a hospital showed substantial intra-rater agreement in the second assessment. Amongst all participants, the median intra-rater reproducibility was substantial (κ = 0.71). OF 3 fractures were rated the poorest amongst all sub-categories. Conclusion: Overall, the AO Spine-DGOU Osteoporotic Fracture Classification showed moderate to substantial inter-rater agreement as well as intra-rater reproducibility regardless of work-setting, surgical experience, level of trauma center and surgical specialty. Non-spine colleagues’ ratings were inferior to the ratings of spine surgeons, which suggests that training for non-spine disciplines should be educated towards this classification.

ID: 1763

A254: Medico economic comparison of spinal augmentation versus orthopaedic corset for the treatment of spinal compression fractures

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

¹ Military Hospital of Tunis, Tunis, Tunisia

Introduction: Kyphoplasty augmentation is widely employed for the treatment of recent spinal compression fractures. Conservative orthopedic treatment with a corset is still also valid alternative. The aim of our study was to compare these two therapeutic strategies in terms of analgesic efficiency, radiological results, morbidity and cost. Material and Method: We conducted a prospective randomized study from January 2016 to May 2022. We included patients with recent traumatic spine fractures type Magerl A3.1. The treatment choice was randomized including kyphoplasty and orthopedic treatment with a corset. Follow-up was done at 1, 12 and 24 months and included functional results (VAS, EQ-5D, ODI), radiological assessment (vertebral kyphosis, regional traumatic angle) and economic cost (material costs, rehabilitation period, consultations, time to return to work). Results: We included 50 patients, 25 in the Kyphoplasty group and 25 in the Corset group. VAS scores were significantly improved for all patients, with no difference between the two groups. ODI and EQ-5D scores were also significantly improved for both groups, but with faster kinetics in the Kyphoplasty group, with a significant difference at 1 month (p < 0.001). Radiological correction of vertebral kyphosis was significantly better in the Kyphoplasty group (p < 0.001) at every stage of follow-up. A loss of correction assessed by regional traumatic angle occurred only in the Corset group. The material cost of Kyphoplasty was higher than that of the Corset (p < 0.01), but associated with a shorter hospital stay, fewer consultations, less rehabilitation (p < 0.001) and a significantly shorter duration of work stoppage (p < 0.0001). There was no difference between the two groups in the prevalence or severity of complications. Conclusion: There was no statistical difference in analgesic efficiency between the 2 therapeutic methods. On the other hand, without any additional morbidity, patients treated with Kyphoplasty augmentation had better radiological results, shorter hospital stays, a quicker return to work and a lower burden of care.

ID: 1527

A255: Operative treatment of thoracolumbar fractures in patients with ankylosing spinal disorders: how many levels of fixation is enough?

Emily Hunt ¹ , Celeste Tavolaro ¹ , Karina Katchko ¹ , Eli Bunzel ¹ , Julie Agel ¹ , Carlo Bellabarba ¹ , Haitao Zhou ¹

¹ Harborview Medical Center, University of Washington, Department of Orthopaedic Surgery & Sports Medicine, Seattle, United States

Introduction: Despite their distinct etiologies, the two primary ankylosing spinal disorders (ASD) - diffuse idiopathic skeletal hyperostosis (DISH) and ankylosing spondylitis (AS) - both lead to spinal ankylosis, making the spine more vulnerable to similar unstable fractures. Individuals with ASD face a fourfold increase in fracture risk compared to the general population. Surgical management of spine fractures in these patients is associated with higher rates of perioperative complications and a greater one-year mortality risk. In the context of ASD, selecting between number of instrumented levels - two levels versus three levels above and below the injury - entails a trade-off between biomechanical stability and surgical morbidity. This study aims to assess the outcomes associated with different multilevel posterior instrumentation constructs in patients with ankylosing spinal disorders and thoracolumbar fractures. Material and Methods: A retrospective study was conducted on patients treated for thoracic and lumbar spine fractures associated with ankylosing spine disorders between 2005-2020 at a single, academic, level 1 trauma center. Patients were categorized into two groups based on the extent of posterior instrumentation: one group had instrumentation two levels above and below the injury (4 or 5 instrumented levels), and the other had instrumentation three levels above and below the injury (6 or 7 instrumented levels). Data collected included demographics, comorbidities, operative details, hospital data, and 90-day postoperative outcomes. Statistical analyses were performed using Student’s T-tests for continuous variables and Fisher’s Exact and Chi-square tests for categorical variables. Results: The study identified 197 cases of ASD (64 AS and 133 DISH) with fractures of the thoracic and/or lumbar region. Of these, 90 patients had instrumentation two levels above and below the injury, and 107 patients had three levels above and below. Mean instrumented levels was 4.61 ± 0.49 for two levels above and below and 6.28 ± 0.53 for three levels above and below (p < 0.001). Mortality within 90 days from index procedure was 14.2%, with no significant difference between groups. The three levels above and below group had a higher 90-day reoperation rate (17.8% versus 6.7%, p = 0.030) and higher rate of surgical site infection (15.9% versus 5.6%, p = 0.024). The three-level group also experienced significantly greater estimated blood loss (678.32 ± 564.95 vs. 355.67 ± 407.25, p < 0.001) and higher surgical invasiveness index (12.88 ± 1.92 vs. 8.80 ± 1.93, p < 0.001). Rate of hardware-related reoperation within 90 days, including screw revisions and acute rod failure with increased kyphosis, was comparable between groups (2.8% in three-level vs. 1.1% in two-level, p = 0.627). Conclusion: In this single-center study, patients with ASD and traumatic fractures of the thoracolumbar spine treated with posterior instrumentation two levels above and below the injury or three levels above and below were compared. Fusion constructs with three levels above and below the injured level were associated with increased blood loss, higher surgical invasiveness index, and higher rates of surgical site infection requiring reoperation within 90-days of index procedure. The rate of mechanical or hardware failure between the two groups was not significant. Therefore, fusion of two levels above and below the injury appears to offer adequate fixation with lower associated morbidity in this high-risk population.

ID: 2394

A256: Effectiveness of stentoplasty reduction in osteoporotic fractures

Álvaro Berríos ¹

¹ Hospital Las Higueras Talcahuano, Concepcion, Chile

Introduction: The diagnosis and management of osteoporotic spine fractures is currently well standardised. The OF classification of the German Orthopaedic and Trauma Society is the gold standard. Among its treatment recommendations, cement augmentation of the fractured vertebra without posterior fixation is reserved for OF1, OF2 and some OF3 fractures. The aim of this study was to evaluate the reduction of vertebral collapse and post-traumatic kyphosis in osteoporotic fractures operated on with the balloon stentoplasty technique without posterior fixation and its evolution over time. Material and Methods: A retrospective review was performed from 2019 to date of percutaneous balloon stentoplasties performed by the team under local anaesthesia and sedation. Sixteen patients were selected. These fractures were classified with weight-bearing radiography (standing) and scanning of the affected segment according to OF classification. Measurement of kyphosis (COBB method) was performed on a weight bearing lateral radiograph of the affected segment pre- and post-operatively. Patients were followed up for a minimum of 4 months and an average of 21 months. Reduction failure was defined as patients who did not improve their post-traumatic kyphosis after stentoplasty. Loss of reduction was defined as patients who over time lost the posttraumatic kyphosis reduction gained and exceeded 20° or became symptomatic (axial pain). Results: The average age was 75 years. Of the patients, 81.25% were female (13 patients) and 18.75% male (3 patients). The majority of fractures occurred at the L1 vertebra (50%) and were classified as OF3 (56%), OF2 (31%) and OF4 (12.5%). 75% of the patients (12 patients) had a reduction of the vertebral collapse with stentoplasty. In all of them the reduction was maintained over time and they had good clinical results. An average kyphosis correction of 8.5° was achieved. All patients were left with an acceptable segmental kyphosis (< 20°) with an average of 13°. The remaining 25% of patients (4 patients) were considered to have failed: - 2 patients had intraoperative reduction failure. This was probably due to the unilateral technique (1 stent). The fractures were classified as OF3 and OF4. Despite this, they had a good clinical outcome and did not require a second operation. - 2 patients had a postoperative loss of kyphosis reduction to unacceptable values. Both fractures were classified as OF3. As a common risk factor they had rheumatologic pathology with chronic corticosteroid use. Both patients were reoperated with percutaneous cemented fixation of the segment with good clinical results. Conclusion: Stentoplasty is an effective, safe and low morbidity technique for resolving OF2 and OF3 osteoporotic fractures. It has a collapse reduction success rate of 75% and a clinical success rate of 87.5%. - We do not recommend its use as the sole technique for OF4 fractures. - We do not recommend using the unilateral technique (1 stent). - We suggest a thorough case-by-case assessment of patient risk factors that may predict failure of this technique.

ID: 476

A257: AO Spine-DGOU Osteoporotic Fracture (OF) classification system: internal validation by the AO Spine Knowledge Forum Trauma

Julian Scherer ^1,2 , Andrei Joaquim ³ , Alex Vaccaro ⁴ , Rishi Kanna ⁵ , Mohammad El-Sharkawi ⁶ , Masahiko Takahata ⁷ , Mohamed Ali ⁸ , Gaston Camino-Willhuber ⁹ , Ulrich Spiegl ¹⁰ , Cumhur Oner ¹¹ , Jose Canseco ⁴ , Ratko Yurac ¹² , Lorin Benneker ¹³ , Eugen Cezar Popescu ¹⁴ , Richard Bransford ¹⁵ , Harvinder Singh Chhabra ¹⁶ , Frank Kandziora ¹⁷ , Marko Neva ¹⁸ , Klaus John Schnake ¹⁹

¹ University of Cape Town, Cape Town, South Africa,

² University Hospital of Zurich, Zurich, Switzerland,

³ State University of Campinas, Sao Paulo, Brazil,

⁴ Thomas Jefferson University Hospital, Philadelphia, United States,

⁵ Ganga Hospital, Coimbatore, India,

⁶ Assiut University, Assiut, Egypt,

⁷ Hokkaido University, Hokkaido, Japan,

⁸ Mansoura University, Mansoura, Egypt,

⁹ Policina Gipuzkoa, San Sebastian, Spain,

¹⁰ Klinikum München Harlaching, Munich, Germany,

¹¹ University Medical Center Utrecht, Utrecht, Netherlands,

¹² University del Desarrollo, Vitacura, Chile,

¹³ University of Bern, Bern, Switzerland,

¹⁴ Oblu Emergency Hospital, Iasi, Romania,

¹⁵ University of Washington, Seattle, United States,

¹⁶ Sri Balaji Action Medical Institute, New Delhi, India,

¹⁷ BG Unfallklinik Frankfurt am Main Frankfurt, Frankfurt, Germany,

¹⁸ Tampere University Hospital, Tampere, Finland,

¹⁹ Paracelsus Private Medical University Nuremberg, Nuremberg, Germany

Introduction: Injury classifications are important tools to identify fracture patterns, guide treatment-decisions and aid to identify optimal treatment plans. The AO Spine-DGOU Osteoporotic Fracture (OF) classification system was developed, and the aim of this cross-sectional survey study was to assess the reliability of this new classification system. Material and Methods: 23 Members of the AO Spine Knowledge Forum Trauma participated in the validation process. Participants were asked to rate 33 cases according to the OF classification at two time points, 4 weeks apart (assessment 1 and 2). The kappa statistic (κ) was calculated to assess inter-observer reliability and intra-rater reproducibility. The gold master key for each case was determined by approval of at least 5 out of 7 members of the DGOU. Results: A total of 1386 ratings (21 raters) were performed. The overall inter-rater agreement was moderate with a combined kappa statistic for the OF classification of 0.496 in assessment 1 and 0.482 in assessment 2. The combined percentage of correct ratings (compared to gold-standard) in assessment 1 was 71.4% and 67.4% in assessment 2. The average intra-rater reproducibility was substantial (κ = 0.74, median 0.76, range 0.55 to 1.00, SD 0.13) for the assessed fracture types. Conclusion: The assessed overall inter-rater reliability was moderate and substantial in some instances. The average intra-rater reproducibility is substantial. It seems that appropriate training of the classification system can enhance inter- and intra-rater reliability.

ID: 1843

A258: Does short-segment posterior fixation with index level screws improve outcome as compared to a long-segment posterior fixation for thoracolumbar fractures of the spine? A study of clinical outcomes

Laksh Agrawal ¹ , Shrinivas Prabhu ¹ , Gayatri Mehta ¹ , Anil Khandekar ¹ , Nilesh Vishwakarma ¹

¹ MGM Hospital, Kamothe, Orthopaedics, Navi Mumbai, India

Introduction: Thoracolumbar fractures are the most common spinal injuries. Although treatment remains controversial in some fracture types, posterior fixation is the most frequently used surgical technique to restore vertebral body height, correct kyphotic deformity, restore spinal stability and indirectly decompress the spinal canal. The use of transpedicular screws at the fractured level provides the advantages of a stiffer construct, an increased biomechanical stability, and the effect of 3- point fixation of the unstable segment guard against failure of the construct. Currently, short-segment pedicle instrumentation for thoracolumbar fractures is gaining popularity. Other- wise, long-segment fixation may be chosen as another treatment method. The purpose of this study was to understand whether a short-segment posterior instrumentation with index level pedicle screw provides comparable results when compared to long segment posterior instrumentation in single level thoracolumbar fractures of the spine. Material and Methods: 54 patients with single level thoracolumbar fractures undergoing posterior instrumentation were assessed and the decision to use long segment fixation or short segment fixation with index level pedicle screw was randomised. A total of 27 patients were operated with short segment fixation with index level pedicle screw and 27 patients with long segment fixation. All patients were evaluated pre- and post-operatively and for one year follow up for angle of correction, pain, neurological state, post-operative stiffness, Oswestry Disability Index and adjacent segment degenerative changes. Results: Twenty-five patients (50%) had short segment and 25 (50%) had long-segment fixation. In the short segment group, the pre-operative mean Cobb’s angle was 19° ± 3° and the angle of correction was 8° ± 2° after 1 year, while in the long segment group, the pre-operative mean Cobb’s angle was 19° ± 4° and the angle of correction was 9° ± 2°. Regarding pain, in the short segment group, the pre-operative visual analogue scale (VAS) was 6.16 ± 1.83 that was reduced to 1.92 ± 0.6 at the 1-year follow-up, while the long segment group VAS was 6.26 ± 1.87 pre-operatively that was reduced to 2.06 ± 0.62. 20% patients had post operative stiffness measured using Modified Schober’s test at 1 year follow-up in the group of patients with short segment fixation with index screw and 32% patients had post operative stiffness in the group of patients with long segment fixation. 32% showed adjacent segment DJD in short segment fixation with index screw while 44% patients in long segment fixation. Conclusion: In this study, short segment fixation with index level pedicle screw provided comparable results when compared to a long segment fixation in terms of Angle of correction achieved and patient specific Oswestry Disability Index. However, a study with a larger sample size would be required to adequately conclude that one form of fixation is superior to the other. In terms of operating time, blood loss, injury to the motion segments short segment fixation with index screw definitely confers more advantages vis -a-vis clinical outcome.

ID: 2647

A259: Sick leave and return to work after a thoracolumbar burst fracture - a register-based study comparing operative and non-operative treatment

Simon Blixt ^1,2 , Fabian Burmeister ³ , Lukas Bobinski ³ , Sebastian Mukka ³ , Karin Johansson ⁴ , Olof Westin ⁵ , Peter Försth ² , Paul Gerdhem ^1,2

¹ Uppsala University Hospital, Department of Orthopaedics and Hand Surgery, Uppsala, Sweden,

² Uppsala University, Department of Surgical Sciences, Uppsala, Sweden,

³ Umeå University, Department of Surgical and Perioperative Sciences (Orthopaedics), Umeå, Sweden,

⁴ Karolinska Institutet, Stockholm, Sweden,

⁵ Institute of Clinical Sciences at Sahlgrenska Academy, Gothenburg, Sweden

Introduction: Treatment of thoracolumbar burst fractures is controversial and includes both operative and non-operative options. Operative treatment may provide advantages such as earlier mobilization and faster return to normal activities. The aim of this study was to compare the days on sick leave and assess predictors of return to work between operatively and non-operatively treated thoracolumbar burst fractures in neurologically intact patients. Material and Methods: Patients with a thoracolumbar (Th10-L3) burst fracture within working age (18-66 years) without spinal cord or cauda equina injury were identified in the Swedish Fracture Register. Medical images were collected and reviewed to verify correct fracture classification. Data from the Swedish Social Insurance Agency was collected to assess number of days on sick leave and the reason for sick leave. Subgroup analysis was made for incomplete (A3) and complete burst fracture (A4), The thoracolumbar injury classification and severity score (TLICS), Thoracolumbar AOSpine Injury Score (TL AOSIS) and Load Sharing Classification (LSC) scores. Mann Whitney-U test was used to compare the number of days on sick leave. Chi-square test was used to compare the proportion of patients who had returned to work at 3 and 6 months. Multivariate linear regression was used to determine predictors for time to return to work. Results: A total of 228 patients were included, with 136 non-operatively treated and 94 operatively treated patients respectively. The operatively treated patients had more severe burst fractures with a higher ratio of A4 fractures (73% vs 37%), higher mean TLICS (3.7 vs 2.7), higher mean TL AOSIS (5.5 vs 4.1), higher mean LSC score (7.6 vs 6.8), more severe local kyphosis (11.8° vs 8.2°) and canal compromise (168.1 mm2 vs 213.0 mm2) compared to the non-operatively treated patients. The mean total number of days on sick leave was 149 days after injury. 59 patients did not have registered sick leave. No difference was seen between operatively and non-operatively treated patients in number of days on sick leave (160 and 142 days respectively, p = 0.3). The proportion of patients who had returned to work at 3 and 6 months after injury was not significant. Subgroup analyses did not reveal any significant differences between groups (all p > 0.05). The regression model explained 70% of the variability in sick leave after burst fracture, with age and sick leave the year before injury as significant variables. Conclusion: The number of days on sick leave after a thoracolumbar burst fracture is similar between operatively and non-operatively treated patients suggesting no benefit with operative treatment regarding return to work. However, the groups did differ substantially in fracture severity. Further randomized studies are essential to determine whether operative treatment may confer any advantages regarding sick leave patterns.

ID: 1834

A260: Complications after triangular osteosynthesis for spinopelvic injuries: a systematic review

Anas El Zouhbi ¹ , Michael Daaboul ² , Karim Hamdan ¹ , Siraj Sayegh ² , Ahmed Hassan ³ , Elie Najjar ³

¹ American University of Beirut, Faculty of Medicine, Beirut, Lebanon,

² American University of Beirut Medical Center, Division of Orthopedic Surgery, Beirut, Lebanon,

³ Queen's Medical Centre, Nottingham University Hospital, Nottingham, United Kingdom

Introduction: Spinopelvic injuries encompass a wide range of fracture patterns involving the lumbopelvic junction and the sacrum, subsequently affecting the spinopelvic biomechanics and stability. Their surgical management is very challenging, being associated with a wide range of complications, including wound dehiscence, surgical site infection, nonunion and chronic disabling low back pain. Conventional methods like iliosacral screws and posterior plating are often unable to neutralize vertical shearing forces and are associated with a high incidence of nonunion and malunion. Triangular Osteosynthesis, which was first described in the early 2000s, emerged as a more effective technique and is gradually becoming the working horse for managing such injuries. The objective of our study is to systematically review the literature on the management of spinopelvic injuries with triangular Osteosynthesis and assess the associated complications. Methods: A systematic literature review was conducted according to PRISMA guidelines from the date of inception till June 2024, focused on full-text studies in indexed journals evaluating triangular Osteosynthesis for traumatic spinopelvic injuries. The databases through which our search was conducted included PubMed, EMBASE, and Web of Science. Only English articles with available abstracts were included, excluding non-traumatic indications, surgical techniques, expert opinions, animal studies, and other non-peer-reviewed materials. Results: A total of 1327 records were retrieved for title and abstract screening. After full-text screening, 18 articles were included in the final analysis. Most were retrospective (13 articles vs five prospective articles) and were either case series or cohort studies (Level III or IV evidence). The studies included 431 patients with a minimum follow-up period of 8 months. Their age ranged between 15 and 78 years of age, with the most common mechanism of injury being falling from height, followed by motor car accidents. All patients received either open or percutaneous fixation, with only two studies using S2 alar iliac screws as a pelvic anchoring point and the rest using iliac screws. Regarding the complication profile of the procedure, the most commonly encountered complications were prominent implants (13.45%), followed by surgical site infection and wound dehiscence (6.26% and 2.78%, respectively). Regarding fracture healing-related complications, 13 patients (3.02%) developed implant loosening. Only three patients developed nonunion (0.7%) and two developed sacral malunion (0.46%). Finally, as for neurological complications, eight patients (1.86%) developed iatrogenic nerve injury. Out of the nine articles that reported the Majeed score, 78% of the patients (n = 137) were reported as excellent, 21.12% (n = 37) reported as either good or fair and only one patient (0.57%) was reported as poor. Conclusion: Despite the relatively high incidence of prominent implants and soft tissue-related complications, triangular Osteosynthesis is still considered a reliable option in managing those complex injuries, with a very low incidence of nonunion and favourable functional outcomes. Other modifications to the standard techniques can be utilized to reduce the high rate of complications, including percutaneous fixation, PSIS osteotomy, and S2 alar iliac screws.

ID: 2567

A261: The near-near-far-far surgical construct is a valid and cost-saving technique for treating ankylosed thoracic spine hyperextension injuries

Mark Xu ¹ , David Gendelberg ¹ , Anthony di Giorgio ¹ , Ashraf El Naga ¹

¹ University of California, San Francisco, United States

Introduction: Surgical treatment of thoracic hyperextension injuries in the ankylosed spine typically involves stabilizing the fracture 3 levels above and 3 levels below the fracture. The Near-Near-Far-Far (NNFF) surgical construct technique involves skipping the middle fixation level of both the proximal and distal 3 levels. For example, in a patient with a T9-10 hyperextension injury, bilateral pedicle screws are inserted at T7, T9, T10, and T12, with the T8 and T11 levels left uninstrumented. Benefits of this technique include the cost savings from implant and operating room time, as well as potential decreased surgical risks and radiation related to pedicle screw insertion. We hypothesize that the NNFF construct is a valid and cost-saving technique that maintains sagittal alignment with low re-operation rates. Material and Methods: This was a retrospective cohort study of 11 consecutive AOSpine B3 thoracic hyperextension injuries in patients with ankylosed spines and underwent the NNFF surgical construct technique. Demographic data, injury level, surgical fixation details, complications, re-operation rate, and follow-up length of time were obtained. Intra-operative prone and post-operative standing kyphosis angles above and below the fractures were measured. Primary outcome was re-operation rate due to construct failure. Implant costs at our institution were also obtained. T tests were used to compare the sagittal kyphosis angle between intra-operative and post-operative radiographs (significance p < 0.05). Results: Average age of patients was 74. All were men. Thoracic hyperextension injury levels ranged from T1 to T12. Average number of levels included in the fixation construct was 6. Six patients underwent open fixation versus 5 percutaneous. There was no significant difference between change in the average sagittal kyphosis angles above and below the fracture from intra-operative prone to post-operative standing radiographs (2.09 degrees, p=0.7357). Three patients underwent re-operations: 2 underwent an irrigation and debridement for post-operative wound infection, and 1 patient sustained a subsequent proximal fracture approximately 3 years later and underwent stabilization proximally. No patients underwent reoperation for failure of fixation related to the thoracic fracture stabilization. Average follow-up time was 49 months (range 3-83). Each patient had 2 skipped uninstrumented levels, which is the equivalent of saving 4 pedicle screws and 4 set screws. Per patient, the average implant savings for our institution was $2800 and $3480 for polyaxial and cannulated screws respectively, not including cost savings for OR time and personnel. Conclusion: In our study, anklyosed spine patients with thoracic hyperextension injuries undergoing the Near-Near-Far-Far surgical construct demonstrated no re-operation rates for construct failure, maintenance of sagittal alignment, and cost savings of $2800 and $3480 per patient for polyaxial and cannulated pedicle screws respectively, not including cost savings for OR and personnel time. Future studies with larger patient size and longer follow-up lengths are underway.

OP30: Navigations and Robotics 1

ID: 1042

A262: Navigation assisted endoscopic excision of osteoid osteoma in 21 year old male - a technical note

Ayush Sharma ¹

¹ Dr B R Ambedkar Memorial Hospital, Spine Surgery, Mumbai, India

Introduction: The osteoid osteoma is a benign osteogenic tumour most commonly affecting femur while affection of Lumbar spine is relatively rare. There are various treatment options like Surgical excision, Radiofrequency Ablation (RFA), CT-guided cryoablation and MR-guided focused ultrasound. Navigation assisted Endoscopic Excision is a novel technique which appears to be an innovative with promising diagnostic and therapeutic option. Study Design: A 21-year-old previously healthy male presented with chronic back pain since 2 years which aggravated in night and relieved by use of NSAIDs. CT and MRI scans of Lumbar spine showed round nodule at left lamina of L2 vertebra suggestive of bone tumour which is in close proximity to neural structures. The patient was planned for navigation assisted endoscopic resection in prone position under general anaesthesia. 3D C-arm was used to scan the lumbar spine and data was analysed using Brainlabs Navigation System. With the help of Navigation probe accurate trajectory was confirmed for Endoscope to reach lamina of L2 from right side then with the help of navigated burr drilling of lamina was done and under visualisation nidus was removed en bloc. After that Radiofrequency Ablation of margins was done and sample sent for histopathological examination. Discussion: Histopathological diagnosis came out to be osteoid osteoma. Traditional open surgical method may result in the absence of accurate localisation, excessive surgical resection of bone, spinal instability or approach related morbidity. New surgical modalities like RFA, cryoablation and MR guided ultrasound cause minimal damage to bone but carry risk of damage to adjacent neural structures and lack histological diagnosis. Navigated endoscopic surgery offers advantage of minimal incision, better visualisation, protection of neural structures, histological diagnosis. Conclusion: Navigation assisted endoscopy has resulted in successful excision of osteoid osteoma close to the neural structure with more precision, minimal invasive approach. It appears to be an innovative and potentially promising diagnostic and therapeutic approach as it is safe, effective and relatively low morbidity intervention.

ID: 2577

A263: Assessing the impact of intraoperative image-guided spinal navigation technologies in endoscopic lumbar spine surgery: a systematic review and meta-analysis

Yu-Che Wang ¹ , Hsu-I Chou ² , Ying Fong Su ³ , Rafael Garcia de Oliveira ⁴ , Abhinav Sharma ⁵ , Yang-Ching Chen ⁶ , Anh Tuan Bui ⁷ , Ching-Yu Lee ³ , Tsung Jen Huang ³ , Don Park ⁵ , Meng-Huang Wu ³

¹ Taipei Medical University Hospital, Department of Medical Education, Taipei, Taiwan,

² Taipei Medical University, School of Medicine, College of Medicine, Taipei, Taiwan,

³ Taipei Medical University Hospital, Department of Orthopedics, Taipei, Taiwan,

⁴ Virginia Mason Medical Center, Seattle, United States,

⁵ UC Irvine, Department of Orthopedic Surgery, Orange, United States,

⁶ Wan Fang Hospital, Department of Family Medicine, Taipei,

⁷ Vietnam Military Medical University, Department of Spine Surgery, Military Hospital, Hanoi, Viet Nam

Study Design: Meta-analysis. Objectives: This study aimed to evaluate whether the use of intraoperative image-guided navigation provides perioperative and clinical advantages in endoscopic lumbar spine surgery (ELSS). Methods: We searched the databases of PubMed, Europe PMC, Scopus, Cochrane Library, and ClinicalTrials.gov for articles comparing intraoperative image-guided navigation with conventional C-arm fluoroscopy in patients undergoing ELSS. Outcomes included perioperative outcomes such as operation time, puncture attempts, cannulation time and radiation dose; clinical outcomes such as length of stay, visual analog scale (VAS) score, Oswestry Disability Index (ODI). Results were summarized using the mean difference (MD) or standardized mean difference (SMD) with accompanying 95% confidence intervals (CI). Results: Seventeen studies (1,296 patients) were included in the meta-analysis. Intraoperative image-guided navigation in ELSS had significantly shorter total operation time (MD, -12.20 minutes; p < 0.0001), fewer puncture attempts (MD, -2.45 times; p = 0.0179), shorter cannulation time (MD, -12.59 minutes; p = 0.0003), lower radiation dose (SMD, -4.18; p < 0.0001), fewer fluoroscopy times (MD, -16.47 times; p = 0.0116), shorter length of hospital stay (MD, -0.46 days; p = 0.038) compared with C-arm fluoroscopy. There were no differences in VAS for back, VAS for leg or ODI up to 1 year of follow-up. No major complications were reported in either group. Conclusions: Intraoperative image-guided navigation in ELSS has been demonstrated to be an effective and safe technique with improvements in total operation time and radiation exposure that bring benefits to patients, surgical teams and health systems. It may also shorten the surgeon's learning curve compared with conventional C-arm fluoroscopy.

ID: 462

A264: Integrated optical and magnetic navigation for simplified percutaneous transforaminal endoscopic lumbar discectomy a novel approach

Aixing Pan ¹ , Xingchen Yao ¹ , Junpeng Liu ¹

¹ Beijing Chaoyang Hospital, Orthopaedic Surgery, Beijing, China

Introduction: This study aims to evaluate the clinical benefits of the integrated optical and magnetic surgical navigation system in assisting transforaminal endoscopic lumbar discectomy (TELD) for the treatment of lumbar disc herniation (LDH). Material and Methods: A retrospective analysis was conducted on patients who underwent TELD for LDH at our hospital from November 2022 to December 2023. Patients treated with the integrated optical and magnetic surgical navigation system were defined as the navigation-guided transforaminal endoscopic lumbar discectomy (Ng-TELD) group (30 cases), while those treated with the conventional X-ray fluoroscopy method were defined as the control group (31 cases). Record and compare baseline characteristics, surgical parameters, efficacy indicators, and adverse events between the two patient groups. Results: The average follow-up duration for the 61 patients was 11.8 months. Postoperatively, both groups exhibited significant relief from back and leg pain, which continued to improve over time. At the final follow-up, patients’ lumbar function and quality of life had significantly improved compared to preoperative levels (p < 0.05). The Ng-TELD group had significantly shorter total operation time (58.43 ± 12.37 vs. 83.23 ± 25.90 min), catheter placement time (5.83 ± 1.09 vs. 15.94 ± 3.00 min), decompression time (47.17 ± 11.98 vs. 67.29 ± 24.23 min), and fewer intraoperative fluoroscopies (3.20 ± 1.45 vs. 16.58 ± 4.25) compared to the control group (p < 0.05). There were no significant differences between the groups in terms of efficacy evaluation indicators and hospital stay. At the final follow-up, the excellent and good rate of surgical outcomes assessed by the MacNab criteria was 98.4%, and the overall adverse event rate was 8.2%, with no statistically significant differences between the groups (p > 0.05). Conclusion: This study demonstrates that the integrated optical and magnetic surgical navigation system can reduce the complexity of TELD, shorten operation time, and minimize radiation exposure for the surgeon, highlighting its promising clinical potential.

ID: 1856

A265: Evaluation of coronal and sagittal alignment and clinical outcomes in adult spine deformity (ASD) surgical treatment: navigation versus free hand technique

Michele Inverso ¹ , Calogero Velluto ¹ , Maria Ilaria Borruto ¹ , Davide Messina ¹ , Laura Scamuzzo ¹ , Luca Proietti ¹

¹ Spine Surgery, Department of Aging, Orthopaedic and Rheumatological Science, Fondazione Policlinico Universitario Agostino Gemelli IRCSS, Rome, Italy

Introduction: Navigation technologies have increased their popularity in spine surgery in the last years. This technology, by processing and reconstructing real-time data, enhances the accuracy of screw positioning and reduces radiation exposure for surgeons. Few studies in medical literature have explored the improvement in spinopelvic parameter correction through 3D reconstruction and intraoperative assessment compared to traditional techniques. The present study aimed to radiographically evaluate the enhancement of spinopelvic parameters, accuracy in screws positioning, and clinical outcomes in patients underwent surgery for adult spinal deformity (ASD). Material and Methods: Forty patients affected by ASD were prospectively collected and retrospectively evaluated at a single institution. Patients were divided into two groups. Group A (22 patients, 5 males and 17 females), underwent surgery using intraoperative navigation; Group B (18 patients, 7 males and 11 females), underwent surgery with free-hand technique. All patients were seen at regular intervals. Preoperative assessment of spinopelvic parameters and L1PA angle (calculated by a line from the center of L1 vertebral body to the axis of femoral head and a line from the axis of the femoral head to the center of the S1 endplate) and CSVL (for the coronal imbalance) was conducted using long standing X-ray. CT, and MRI were also pre-operatively performed. Postoperative follow-up included long standing X-rays with evaluation of spinopelvic parameters and screw positioning. Clinical outcomes were evaluated by VAS scale and ODI questionnaire at regular intervals. Statistical analysis was conducted using SPSS statistic software using t-student test for parametric data and qui-squared test for non-parametric data. Results: Forty patients divided in 2 groups (Group A with an average age of 61.2 years) and Group B (with an average age of 59.3 years) were followed for a minimum of 12 months. Mean follow-up was 12.3 months in Group A and 15.6 months in Group B. No hardware failures were reported in either group. Considering the spinopelvic parameters: in Group A patients a greater recovery of lumbar lordosis and L1PA angle and a satisfactory restore of the spinopelvic parameters and L1PA angle (a medium recovery 13° ± 3°) compared to preoperative time was observed. Group B showed a satisfactory improvement of spinopelvic parameters, L1PA angle values (a medium recovery of 10° ± 4°) and coronal imbalance (CSVL) compared to pre-operative time. Group A showed a better improvement of the analyzed parameters compared to Group B. No statistically significant difference was observed in screw positioning comparing the two groups. A greater accuracy was observed in group A in the size of screws choice. Conclusion: Navigation, using intraoperative “stitching” and real-time measurement of spinopelvic parameters, allowed for intraoperative adjustments, leading to improved radiological outcomes, as seen in our Group A. Furthermore, real-time visualization of screw dimension allows a better and easier screw positioning, with the use of screws, that could be defined as custom made for the patient’s pedicle and vertebral body size.

ID: 2855

A266: Augmented reality surgical navigation in transforaminal lumbar interbody fusion (TLIF) procedure: a comparative study

Giuseppe Barbagallo ¹ , Giacomo Cammarata ¹ , Cateno Petralia ¹ , Angelo Basile ¹ , Carmelo Vitaliti ¹ , Francesco Certo ¹

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

Introduction: Transforaminal lumbar interbody fusion (TLIF) is a well-established procedure for treating degenerative lumbar spine conditions. With advancements in medical technology integration of augmented reality (AR) into surgical procedures holds significant potential to enhance precision, improve workflow and reduce complications. Traditional TLIF heavily relies on fluoroscopy or neuronavigation to guide surgeons during critical steps such as pedicle screw placement. However, recent studies suggest that AR may improve outcomes by offering surgeons a more intuitive visual overlay that facilitates real-time guidance throughout the procedure. This study aims to evaluate the role of AR in minimally invasive (mini-open) TLIF compared to fluoroscopy-only or neuronavigation-assisted techniques. Material and Methods: A retrospective study was conducted analyzing data from 69 patients who underwent mini-open TLIF between January and August 2024. Patients were divided into three groups: those who underwent surgery using fluoroscopic guidance only, those using neuronavigation assistance, and those supported by AR. Data collected included patient demographics, surgery duration, radiation exposure, pedicle screw placement accuracy, postoperative complication rates, and hospital stay. Postoperative imaging was segmented using the Elements Smartbrush software by BrainLab (BrainLab, Munich, Germany) to evaluate surgical accuracy, alignment, and osteotomy volume. Statistical analysis was performed to compare operative times, radiation exposure, and clinical outcomes among the groups. Results: The patient cohort comprised 69 patients (29 males and 40 female), with an average age of 62.7 years ± 12.3 (range 35-87). Among them, 28 underwent fluoroscopy-only TLIF, 36 received neuronavigation assistance, and 5 underwent AR-supported surgery. Key findings indicated no statistically significant differences in operative times between the groups (p = 0.2285). The average surgical times were 297.5 minutes for the fluoroscopy group, 387.5 minutes for the neuronavigation group, and 270 minutes for the AR group. Additionally, radiation exposure for both patients and the surgical team was significantly lower in the AR group, with median radiation exposure of 124.2 Cy*cm² for fluoroscopy group, 9.195 Cy*cm² for navigation and 0.0 Cy*cm² for AR group (p = 0.00047). No significant differences were observed in postoperative volume of osteotomy, accuracy of pedicle screw placement and postoperative complication rates between the groups; however, AR-assisted procedures showed a trend towards fewer revisions due to screw misplacement. Subjective feedback from surgeons indicated that AR enhanced their visualization and confidence, especially in complex anatomical cases or revision surgeries. Conclusion: The integration of augmented reality into mini-open TLIF procedures offers several advantages over traditional methods relying on fluoroscopy and neuronavigation. AR not only significantly reduces radiation exposure for both patients and surgical teams but also enhances surgical confidence and accuracy in complex anatomical cases. While AR-assisted surgeries demonstrated comparable operative times and hospital stays, the reduction in radiation exposure and trends toward fewer revisions suggest that AR could play a valuable role in refining surgical techniques. Further large-scale studies are necessary to confirm these findings and explore the long-term benefits of AR in spinal surgeries, particularly for more complex cases and revision surgeries.

ID: 2012

A267: Augmented reality enhances lateral interbody fusion by improving efficiency and reducing radiation

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 digital overlay in the visual field. AR has recently been integrated into spinal fusion surgery for navigation of pedicle screws. However, the utilization of augmented reality in spine surgery is rapidly expanding to incorporate additional uses. Lumbar lateral interbody fusion cases can be challenging secondary to positioning of the patient as well as safe access to the lateral disc space. Extensive fluoroscopy is necessary to find a safe corridor into the disc space while avoiding the lumbar plexus. Here we demonstrate the novel addition of AR technology to the life cycle of lateral lumbar interbody fusion surgery. Material and Methods: The patient was positioned in the either left lateral decubitus position for extreme lateral or prone for prone transpsoas approach. The patient marker was carefully positioned in the ilium to be easily visualized for the lateral approach. An intra-operative CT was performed, and the data loaded into Xvision console for processing. The surgeon was fitted with the Xvision head-mounted display. The incision and dissection to the disc space were completed in standard fashion. Next, a guidewire with an attached navigation array was then navigated into the target disc space. 3D AR visualization was utilized to optimize positioning in the disc space to avoid the lumbar plexus and vasculature without the use of fluoroscopy. The area around the guidewire was stimulated and once deemed safe, retractors were placed and the lateral interbody fusion continued in standard fashion. Results: A total of five patients underwent augmented reality driven lateral interbody fusion for a total of eight levels. Two were revision surgeries for adjacent segment disease while three cases were virgin spines. Levels spanned L2-5 (L2/3: 2, L3/4: 5, L4/5: 1). With each level, AR successfully navigated a guidewire safely into an idea the disc space without the need for fluoroscopy. Additionally, AR was used to plan the discectomy and final position of interbody. No patients experienced major surgical complications or lumbar plexopathies. There was a significant reduction (p < 0.01) in fluoroscopy time compared with traditional XLIF approach. All instrumentation were accurately positioned as verified by post-operative Xrays. For patients undergoing single position surgery (n = 3, percutaneous MIS pedicle screws were placed using AR the same time without the need for an additional OR spin. Conclusion: AR can successfully be utilized for lateral lumbar interbody fusion. The integration of the technology allows for not only placement of pedicle screws, but also precise and safe navigation into the lateral disc space. This reduces the traditional reliance on fluoroscopy when accessing the lateral disc space. AR navigation can be utilized with nearly all instrumentation and used to perform most surgical steps beyond pedicle screw placement, allowing for a precise and efficient procedure. Additionally, AR negates the need for radiation use for access to the disc space and placement of pedicle screws.

ID: 1545

A268: Morphometric analysis and prediction models for screw misplacement in subaxial spine based on 139 consecutive patients operated using image-guided cervicle pedicle fixation method

Lukas Bobinski ¹ , Johan Wänman ¹ , Anders Berglund ² , Hampus Hallberg ² , Joel Axelsson ¹ , Hassib Lewall ¹ , John Duff ³

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

² Epistat, Uppsala, Sweden,

³ I3 Spine International, Department of Neurosurgery, Dubai, United Arab Emirates

Introduction: The cervical pedicle screw (CPS) fixation technique remains challenging due to small bony volume of the pedicles, combined with anatomical variability and cervical mobility. Image-guidance techniques, such as like 3D fluoroscopy, have improved the accuracy and precision of cervical pedicle screw (CPS) screw placement. The objective of this study was to investigate prediction models for screw misplacement in subaxial spine (C3-C6) in patients operated with imaging guided technology (O-arm™ in combination with Stealth Station, Medtronic). Methods: Data were collected from medical records of operated patients at Neurosurgical Service, Department of Clinical Neurosciences, University of Lausanne Hospital (CHUV), Lausanne, Switzerland and Spine Unit and Department of Orthopedics, Umeå University Hospital (NUS), Umeå, Sweden. Image-viewing software (SECTRA) with multiplanar reconstruction (MPR) was used for radiological evaluation. The orthogonal view evaluation method (OVEM) along the axis of the bone corridor of pedicle, was used to classify the accuracy of the screws. The screws were categorized as grade I (no breach), grade II (screw thread cortical breach), grade III (any cortical breach larger than II grade without neurovascular injury) and grade IV (major cortical breach causing neurovascular injury). The diameter of each instrumented pedicle was obtained by measuring its narrowest part either in X (width) or Y (height) axis. Logistic regression was used to obtain odds ratios for screw misplacement (OVEM 3-4) adjusted for pedicle diameter, side and level of the instrumented vertebrae. Receiver operating characteristics (ROC) analysis was used for predictability. The optimal cut-off for pedicle diameter was obtained using restricted cubic spline. A p value < 0.05 was considered statistically significant. The statistical analysis was performed using R version 4.3.0. Results: A total of 410 CPS were implanted in 139 patients (36 men and 13 women at CHUV and 60 men and 30 women at NUS) in subaxial spine. The total number of screws classified as OVEM I was 113 (27.5%), grade II 164 (40%), and grade III 131 (32%). There were two grade IV screws (0.5%). The size of the instrumented pedicle, as well as level of instrumentation, demonstrated a statistically significant correlation with screw misplacement (p < 0.001 and 0.022 respectively). Operated side (left vs right) was not significant. The C3 level had the smallest pedicle diameter, which was thus used as a reference. There was a statistically significant correlation between operated levels (C5, p < 0.001) and (C6, p = 0.026) and screw misplacement. The 5.3 mm cut-of value of pedicle diameter demonstrated that odds ratio for screw misplacement increased exponentially with decreasing size of the pedicles. The ROC prediction model for misplacement demonstrated the highest values for the left C5 pedicle (AUC = 0.7699 95% CI: 0.6308-0.909, specificity 0.6765, sensitivity 0.8235). Conclusions: The CPS placement in the subaxial spine is technically demanding, but the risk for neuro-vascular injury is low. A small diameter of the pedicles and the C5 vertebra level demonstrated the strongest prediction for screw misplacement.

ID: 730

A269: Technique, safety and accuracy assessment of percutaneous pedicle screw placement utilizing computer assisted navigation in lateral decubitus single-position surgery

Anna-Katharina Calek ¹ , Bettina Hochreiter ¹ , Aaron Buckland ²

¹ Balgrist University Hospital, Orthopaedic Surgery, Zurich, Switzerland,

² Spine and Scoliosis Research Associates Australia, Melbourne, Australia

Introduction: Percutaneous pedicle screw (PPS) placement has become a pivotal technique in spinal surgery, increasing surgical efficiency and limiting the invasiveness of surgical procedures. While the accuracy of PPS is critical, the accuracy in placing them in the lateral decubitus position has not been extensively reported. The aim of this study was to analyze the accuracy of computer assisted PPS placement in the lateral decubitus position, as assessed with computed tomography (CT). Material and Methods: Retrospective review of prospectively collected data was performed on 44 consecutive patients treated between 2021 and 2023 with lateral decubitus single-position (L-SPS) lateral lumbar interbody fusion (LLIF), anterior lumbar interbody fusion (ALIF), or combined LLIF/ALIF with bilateral percutaneous pedicle screws (PPS) and rod fixation of 1-3 levels. PPS placement was assessed by CT scans and breaches graded based upon the magnitude and direction of the breach. The laterality of breaches and facet joint violations were assessed. Variables collected included patient demographics, indication for surgery, intraoperative complications, operative time, fluoroscopy time, estimated blood loss (EBL), and length of stay (LOS). Results: Forty-four patients, with 220 PPS were identified. 79.5% of all patients underwent ALIF only, 13.6% underwent LLIF only, and 6.8% received a combination of both ALIF and LLIF. Eleven screw breaches (5%) were identified: ten were Grade II breaches (< 2 mm) and one was a Grade IV breach (> 4 mm). All breaches were lateral. Of all breaches, 63.6% involved down-side screws indicating a trend toward the laterality of breaches for down-side pedicles. When analyzing breaches by level, 1.2% of screws at L5 exhibited a Grade II breach, 13% at L4, and 11.1% at L3 demonstrated Grade II breaches. No facet joint violations were noted. Conclusion: PPS placement utilizing computer assisted navigation in L-SPS is both safe and accurate. An overall breach rate of 5% was found; considering a safe zone of two millimeters, only one screw (0.5%) demonstrated a relevant breach.

ID: 1519

A270: Minimally invasive arthrodesis of the sacroiliac joint: RIALTO Oarm assisted technique - Surgical technique. A center experience

Federico Iaccarino ¹ , Demo Eugenio Dugoni ² , Giacomo Pavesi ¹ , Alessandro Landi ² , Pietro Vittorio La Cava ² , Corrado Iaccarino ¹

¹ UNIMORE, Modena, Italy,

² Centro Chirurgico Toscano, Arezzo, Italy

Introduction: Many techniques for arthrodesis of the sacroiliac joint (SIJ) require a lateral approach by the surgeon. The RIALTO system Oarm-assisted uses a posterior approach to the sacroiliac joint and this allows for less trauma to the muscles, reduced post-operative pain and a quicker resumption of normal activities by the patient. Material and Methods: For surgery to be indicated, patients must meet at least 5 out of 7 criteria: failure of conservative treatment, unilateral pain that does not radiate to the lower limbs, pain localized at the sacroiliac joint level, positive response to at least 3 provocative tests, no generalized tenderness behavior, imaging excluding other causes of pain, 75-80% pain reduction with diagnostic peripheral blocks. In this study the surgical steps that we use at Centro Chirurgico Toscano for minimally invasive arthrodesis of the sacroiliac joint will be exposed. The procedure is performed in neuronavigation and requires the presence of an Oarm, with which the scans for the navigation are carried out. Fenestrated screws are used (ø 12mm), which allow better bleeding of the articular surfaces, resulting in greater osteosynthesis and a consequent effective arthrodesis. The period considered goes from 01/01/2020 to 01/06/2024, 21 patients underwent the procedure. Results: The average time to perform the procedure was 45 minutes. Patients usually remained hospitalized for 3 days, they had to walk with crutches for 30 days, at the end of which they had to carry out a neuroimaging check to gradually abandon the supports. Further checks have been carried out 1,3, 6 months and one year after the operation, to make sure that the arthrodesis has taken place. There were no infections or implant failures and the neurological physical examination remained negative. Conclusion: The RIALTO system Oarm-assisted for minimally invasive arthrodesis of the sacroiliac joint represents an excellent surgical alternative to the treatment of mechanical dysfunction affecting this structure. The surgical times are short and the results obtained so far are encouraging.

OP31: Mis/Endoscopic Spine Surgery 1

ID: 963

A271: Decompression alone versus decompression with fusion (TLIF) for degenerative lumbar spondylolisthesis: Do the 5-year results differ when comparing only minimally invasive surgeries?

Andrew Chan ¹ , Vardhaan Ambati ² , Dean Chou ¹ , Mohamad Bydon ³ , Erica Bisson ⁴ , Steven Glassman ⁵ , Kevin Foley ⁶ , Christopher Shaffrey ⁷ , Eric Potts ⁸ , Mark Shaffrey ⁹ , Domagoj Coric ¹⁰ , John Knightly ¹¹ , Paul Park ⁶ , Michael Wang ¹² , Kai-Ming Fu ¹³ , Jonathan Slotkin ¹⁴ , Anthony Asher ¹⁰ , Michael Virk ¹³ , Regis Haid ¹⁵ , Praveen Mummaneni ²

¹ Columbia University, New York City, United States,

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

³ Mayo Clinic, Rochester, United States,

⁴ University of Utah, Salt Lake City, United States,

⁵ Norton Leatherman Spine Center, Louisville , United States,

⁶ Semmes Murphey Clinic, Memphis, United States,

⁷ Duke, Durham, United States,

⁸ Goodman Campbell Brain and Spine, Carmel, United States,

⁹ University of Virgina, Charlottesville, United States,

¹⁰ Carolina Neurosurgery and Spine Associates, Charlotte, United States,

¹¹ Maxim Spine, Morristown, United States,

¹² University of Miami, Miami, United States,

¹³ Cornell University, New York City, United States,

¹⁴ Geisinger Medical Center, Danville, United States,

¹⁵ Atlanta Brain and Spine, Atlanta, United States

Introduction: Advantages of minimally invasive surgery (MIS) include sparing of muscular and midline osseoligamentous structures. Thus, MIS may hypothetically mitigate the superiority observed for open fusion versus open decompression alone for grade 1 degenerative lumbar spondylolisthesis. Here, we compare 5-year outcomes of MIS transforaminal lumbar interbody fusion (TLIF) versus MIS decompression alone. Methods: We analyzed patients who underwent single-segment MIS TLIF or MIS tubular decompression for grade 1 degenerative lumbar spondylolisthesis from the prospective QOD spondylolisthesis cohort. Univariate and multivariable analyses compared outcomes including Oswestry Disability Index (ODI), numeric rating scale (NRS) back pain (NRS-BP), NRS leg pain (NRS-LP), EuroQol-5D (EQ-5D), North American Spine Society (NASS) satisfaction score, and cumulative related reoperation rate. Results: Overall, 608 patients were identified of whom 143 underwent MIS: 72 (50.3%) TLIF and 71 (49.7%) decompression. The MIS TLIF cohort was younger (62.1 ± 10.5 vs 72.3 ± 9.6 years), had lower rates of diabetes (9.7% vs 22.5%), was more likely to ambulate independently (88.9% vs 85.9%), use private insurance (65.3% vs 26.8%), be employed preoperatively (54.2% vs 23.9%), and had higher baseline NRS-BP (6.9 ± 2.6 vs 5.6 ± 3.2) (p < 0.05). Otherwise, the cohorts were similar for baseline characteristics. MIS TLIF had more blood loss (108.8 ± 85.0 vs 33.0 ± 63.2 mls), longer operative times (228.2 ± 110.7 vs 101.8 ± 48.0 mins), and longer hospitalization lengths (2.9 ± 1.8 vs 0.7 ± 1.2 days) (p < 0.001). 5 years postoperatively, both cohorts had significant mean improvements in ODI, NRS-LP, NRS-BP, and EQ-5D (p < 0.05). MIS TLIF had a significantly lower reoperation rate (5.6% vs 15.5%, p = 0.001). MIS TLIF demonstrated significantly larger reductions in NRS-BP (-4.0 ± 3.5 vs -2.2 ± 3.4) and higher rates of satisfaction (NASS 1 or 2: 81.4% vs 57.6%) (p < 0.05), but similar ODI, NRS-LP, NRS-BP, and EQ-5D (p > 0.05). Multivariate analyses did not identify fusion as a significant predictor of ODI, NRS-LP, NRS-BP, and EQ-5D. Conclusion: While both MIS TLIF and MIS decompression are associated with clinical benefits in well-selected patients, our 5-year results demonstrate that MIS TLIF is associated with fewer reoperations and higher patient satisfaction.

ID: 1177

A272: Single-position prone lateral interbody fusion is associated with improved radiographic and clinical outcomes at one year compared to single-position lateral interbody fusion: a single institution experience

Anthony Yung ¹ , Tobi Onafowokan ¹ , Peter Tretiakov ² , Max Fisher ¹ , Ankita Das ² , Ethan Cottrill ¹ , Isabel Prado ¹ , Iryna Ivasyk ¹ , Olivia Blaber ¹ , Caroline Wu ¹ , Tyler Williamson ³ , Zach Thomas ¹ , Andrew Schoenfeld ⁴ , Muhammad Abd-El-Barr ¹ , Thomas Buell ⁵ , D. Kojo Hamilton ⁵ , Michael Gerling ⁶ , Zorica Buser ⁶ , Nima Alan ⁷ , Andrew Chan ⁸ , Nitin Agarwal ⁵ , Dean Chou ⁸ , Paul Park ⁹ , Peter Passias ¹

¹ Duke University School of Medicine, Division of Spine Surgery, Departments of Orthopaedic and Neurological Surgery, Durham, United States,

² New York Medical College, Valhalla, United States,

³ University of Texas at San Antonio Health Sciences Center, San Antonio, United States,

⁴ Brigham and Women's Hospital, Boston, United States,

⁵ University of Pittsburgh Medical Center, Pittsburgh, United States,

⁶ Gerling Institute, Brooklyn, United States,

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

⁸ Columbia University, New York, United States,

⁹ Semmes Murphy Clinic, Memphis, United States

Introduction: Recent studies highlight the increasing adoption of single-position prone lateral (SP-PL) and single-position lateral decubitus (SP-LD) in Minimally Invasive Spine Surgery (MISS) to reduce operative time, enhance patient safety, and improve surgical accessibility. The goal of this study was to assess the differences between SP-PL and SP-LD achievement of optimal postoperative outcomes and post-operative complication rates. Material and Methods: A consecutive series of 152 Patients with baseline (BL) and 1-year (1Y) postoperative radiographic/HRQL data were included. Patients placed in the SP-PL or SP-LD were isolated. Optimal Outcome (OO) was defined as patients who experienced no complication requiring reoperation and achieved Substantial Clinical Benefit (SCB) for NRS-leg or NRS-back. Means comparison analysis assessed differences in radiographic and clinical outcomes. ANCOVA and multivariable backward stepwise logistic regression were used to adjust for confounders. Results: 59 SP-PL and 93 SP-LD patients were included. At baseline, cohorts were comparable in terms of age, gender, BMI, and CCI. Peri-operatively, SP-PL patients had a significantly lower operative time (207.22 vs 317.5 min; p < 0.001), LOS (3.1 vs 3.6 days; p = 0.033), EBL (244.5 vs 376.3 ml; p = 0.023), and demonstrated lower perioperative complication rate (25.4% vs 41.9%; p = 0.038). Multivariable analysis indicated that SP-PL patients had a lower likelihood of cardiac perioperative complications (OR 0.012; CI 95%: 0.0-0.6; p = 0.026). Immediate postoperatively, SP-PL had a greater degree of segmental lordosis improvement from L1-L2 to L5-S1 (all; p < 0.05). SP-PL patients have a higher likelihood of achieving SCB NRS-Back at 1Y (OR: 8.0; CI 95%: 1.5-42.0; p = 0.014) and MCID NRS-leg at 1Y (OR:4.6; CI 95%:1.002-21.2; p = 0.49). The SP-PL cohort had a significantly greater percentage of OO (96.6% vs 78.5%; p = 0.002) and a higher likelihood of achieving OO in adjusted analysis (OR:10.6; CI 95%: 2.1-53.3; p = 0.004). Conclusion: Patients placed in the SP-PL during minimally invasive spine surgery exhibit a reduced rate of perioperative complications, a higher incidence of SCB, and a superior rate of achieving optimal outcomes at the one-year follow-up. These findings underscore the SP-PL position as a potentially advantageous approach for minimally invasive lumbar fusion.

ID: 2811

A273: Percutaneous navigated C1-C2 (Magerl’s) transarticular screw treatment: case series

Kristian Varga ¹ , Peter Hudak ¹ , Benedikt Trnovec ² , Martin Sedliak ¹ , Jan Kozak ¹ , Milan Liska ¹

¹ Department of Neurosurgery, University Hospital in Bratislava - Ružinov, Bratislava, Slovakia,

² Neurosurgery Department, Bory Hospital, Bratislava, Slovakia

Introduction: Many surgical techniques are used for craniocervical junction trauma treatment. The most common are: Harms, Judet, Magerl. The classical surgical management of unstable craniocervical junction fracture by open surgery is still dominant. Open surgery can affect wound healing, duration of hospital stay and potentially functional status. We present our case series in a percutaneous navigated C1-C2 transarticular (Magerl) screw in trauma case. Material and methods: The patients were in prone position in a Mayfield carbon headholder. The navigation frame was placed on the head holder. An intraoperative, 3D image navigation system was used for the 1,5 cm skin incision on both sides and the optimal placement of the C1-2 transarticular screws. The patients were prospectively evaluated in terms of their clinical, functional, and radiological outcomes with a mean follow-up of 12 months. Results: A total of 16 screws were placed in eight patients by this technique with a mean follow up of 12 months. The mean duration of surgery was 130 minutes and the average blood loss was 30 mL. The patients were discharged from the hospital in early postoperative period. The intraoperative O-arm scan and follow-up CT showed correct placement of screws and wound healing. There were no complication regarding the atlanto-axial stability. Conclusion: Percutaneous navigated C1-C2 screw placement can safely compete most commonly used surgical procedures. This mini-invasive method reduce the blood loss during the surgery, hospital stay and preserve cervical musculature.

ID: 2349

A274: Comparison of clinical effectiveness of full endoscopic lumbar discectomy (FELD) and microdiscectomy (MD) in patients with lumbar disc herniation: a prospective, randomized study of 200 patients

Kajetan Latka ¹ , Dariusz Latka ¹ , Kacper Domisiewicz ¹ , Piotr Lasowy ¹

¹ Institute of Medicine, University of Opole, Department of Neurosurgery, Opole, Poland

Introduction: Lumbar disc disease (LDD) is increasingly prevalent globally, affecting progressively younger populations. Classical lumbar microdiscectomy (MD) has long been the standard treatment for symptomatic disc herniation. However, minimally invasive endoscopic approaches, such as Transforaminal Endoscopic Lumbar Discectomy (TELD) and Interlaminar Endoscopic Lumbar Discectomy (IELD), are gaining popularity. Both MD and endoscopic procedures offer unique advantages and drawbacks. This study compares the clinical effectiveness of these two surgical methods, focusing on postoperative pain relief, functional recovery, and recurrence rates. Patients and Methods: This prospective, randomized trial involved 200 patients aged 18 to 85 years with single-level lumbar disc herniation. None had undergone prior lumbar surgery, and all had symptoms persisting for at least six weeks. The patients were randomly assigned to either MD (100 patients) or endoscopic discectomy (TELD/IELD; 100 patients). MRI scans were performed 24 hours before surgery, 24 hours after surgery, and during follow-ups. Clinical outcomes were assessed using the Visual Analog Scale (VAS) for pain, the Core Outcome Measures Index (COMI), and the Oswestry Disability Index (ODI). Follow-up evaluations were conducted at 1, 3, 6, and 12 months postoperatively. At each follow-up, patients completed the VAS, COMI, and ODI questionnaires, and MRI scans were performed to evaluate disc recurrence or residual pathology. Results: Preliminary findings show a slightly higher recurrence rate in patients undergoing endoscopic discectomy compared to MD. However, endoscopic procedures had no infection risk, reduced hospitalization times, and allowed faster return to work. Additionally, patients in the endoscopic group reported significantly lower VAS back pain scores in the early postoperative period. At the one-month follow-up, patients in the endoscopic group had better COMI and ODI scores than those in the MD group, with these improvements persisting at three months. Specifically, endoscopic discectomy patients showed faster recovery and greater satisfaction in the early months postoperatively. By the six- and twelve-month follow-ups, VAS, COMI, and ODI scores between the two groups converged, showing no significant differences. Despite the slightly higher recurrence rates in the endoscopic group, early postoperative recovery was faster, with patients reporting better outcomes in the first three months. Conclusions: Though endoscopic discectomy techniques (TELD/IELD) remain relatively uncommon in Poland, they demonstrate similar effectiveness to MD, particularly in early recovery. Endoscopic procedures have advantages such as minimal infection risk, faster recovery, and quicker return to work, presenting a potential economic benefit. While recurrence rates may be slightly higher in endoscopic procedures, early functional and pain relief outcomes favor this approach. Further long-term follow-up is necessary to confirm these results.

ID: 1414

A275: Surgical relevance of the venous anatomy of prepsoas space: an anatomic study and radiographic review of 516 patients

Mohamed Macki ¹ , Mario-Cyriac Tcheukado ¹ , David Laczynski ²

¹ Cleveland Clinic Foundation, Neurological Institute, Spine Center, Cleveland, United States,

² Cleveland Clinic Foundation, Heart, Vascular, and Thoracic Institute, Cleveland, United States

Introduction: During a lateral L2-L5 interbody fusion, retroperitoneal anatomy is often an unfamiliar surgical corridor for the spine surgeon who has limited visualization through a long and narrow minimally-invasive retractor system. The venous anatomy anterior to the psoas muscle holds particular importance with an antepsoas approach, in which unexpected bleeding can impede the operation. Venous anatomy thus represents arguably one of the greatest challenges in the anterior-to-psoas surgery. The objective of this study is to define the venous anatomy so that the surgeon can not only understand the source of the intraoperative bleeding but also interpret preoperative image findings that may portend aggressive intraoperative bleeding for the prepsoas approach to the lateral L2-L5 interbody fusion. Material and Methods: All patients undergoing an anterior or lateral lumbar interbody fusion by four surgeons (who specialize in lateral approaches) at a single institution over the past seven years were retrospectively reviewed. Only patients with a preoperative MRI and/or CT myelogram of the lumbar spine were included in the study. Images were screened for aberrant venous anatomy, with a particular emphasis on the left renal vein because of its implications in dilated venous vasculature in the prepsoas space. Results: Of the 516 patients who met the inclusion criteria, fifteen images demonstrated a prominent lumbar, ascending lumbar, and/or reno-lumbar veins which are a collection of antepsoas vessels that communicate with the vena cava, iliac branches, and renal/ gonadal veins. Lumbar veins may also drain into the ascending lumbar vein, which ascend between the psoas muscle and the lumbar vertebrae. The most common indication for engorgement of the anterior-to-psoas veins was an aberrant left renal vein: eleven (2%) and three (0.5%) patients had a retro-aortic and circumferential left renal vein, respectively. This abnormal anatomy causes the aorta to compress – and subsequently enlarges – the left renal vein, which in turn distends the reno-lumbar veins and ascending lumbar vein (anastomoses with the left renal vein via the ascending lumbar communicant vein). Alternatively, a “nutcracker” phenomenon may compress the left renal vein between the aorta and superior mesenteric artery. When these prepsoas veins dilate, flow voids are readily appreciated on preoperative MRI. Conclusion: Identifying a flow void in the prepsoas space most commonly represents a dilated lumbar, ascending lumbar, and/or reno-lumbar veins. These preoperative image findings may foretell aggressive intraoperative bleeding during the prepsoas approach to lateral L2-L5 interbody fusion. Importantly, these veins can be swiftly coagulated or clipped early in the operation without physiologic consequence.

ID: 508

A276: New ipsilateral full endoscopic interlaminar approach for L5-S1 foraminal and extraforaminal decompression: technique description and initial case series

Marco Moscatelli ¹ , Marcos Vaz De Lima ^2,3 , Antonio Roth Vargas ⁴ , Rafael Barreto Silva ⁴ , Marcio Penna De Carvalho ⁵ , Juliano Rodrigues Dos Santos ⁶ , Martin Komp ⁷ , Sebastian Ruetten ⁸

¹ Neurolife, Natal, Brazil,

² Santa Casa De São Paulo, São Paulo, Brazil,

³ Instituto Tecnológico de Aeronáutica - ITA, São José dos Campos,

⁴ Centro Médico de Campinas, Campinas,

⁵ Ortovita, Belém, Brazil,

⁶ Vitória Apart Hospital, Vitória, Brazil,

⁷ St. Anna Hospital Herne/Marien Hospital Herne University Hospital/Marien Hospital Witten, Herne, Germany, Herne, Germany,

⁸ St. Anna Hospital Herne/Marien Hospital Herne University Hospital/Marien Hospital Witten, Herne, Germany

Background: The L5-S1 interlaminar access described in 2006 by Ruetten et al. represented a paradigm shift and a new perspective on endoscopic spinal approaches. Since then, the spinal community has shown that both the traditional ipsilateral and novel contralateral interlaminar approaches to the L5-S1 foramen are good alternatives to transforaminal access. This study aimed to provide a technical description and brief case series analysis of a new endoscopic foraminal and extraforaminal approach for pathologies at the lumbar L5-S1 level using a new ipsilateral interlaminar approach. Methods: Thirty patients with degenerative stenotic conditions at the L5-S1 disc level underwent the modified interlaminar approach. The surgical time, blood loss, occurrence of complications, and clinical outcomes were recorded. The data were compiled in Excel and analyzed using R software version 4.2. All continuous variables are presented as the mean, median, minimum, and maximal ranges. For categorical variables, data are described as counts and percentages. Results: Thirty patients were included in the study. The cohort showed significant improvements in all quality-of-life scores (ODI, visual analog scale of back pain, and visual analog scale of leg pain). Five cases of postoperative numbness and three cases of postoperative dysesthesia have been reported. No case of durotomy or leg weakness has been reported. Conclusions: The fundamental change proposed by this procedure, the new ipsilateral approach, presents potential advantages to surgeons by overcoming anatomical challenges at the L5-S1 level and by providing surgeon-friendly visualization and access. This approach allows for extensive foraminal and extraforaminal decompression, including the removal of hernias and osteophytosis, without causing neural retraction of the L5-S1 roots while maintaining the stability of the operated level.

ID: 1123

A277: An analysis of intraoperative neurophysiological monitoring events during single position minimally invasive spine surgery

Tobi Onafowokan ¹ , Max Fisher ¹ , Anthony Yung ¹ , Giovanni Cervini ² , Ethan Cottrill ¹ , Khoi Than ¹ , Zorica Buser ³ , Nitin Agarwal ⁴ , Thomas Buell ⁴ , Michael Gerling ³ , Paul Park ⁵ , Andrew Chan ⁶ , Nima Alan ⁷ , D. Kojo Hamilton ⁴ , Dean Chou ⁶ , Peter Passias ¹

¹ Duke University School of Medicine, Division of Spine Surgery, Departments of Orthopaedic and Neurological Surgery, Durham, United States,

² Liberty University College of Osteopathic Medicine, Lynchburg, United States,

³ Gerling Institute, Brooklyn, United States,

⁴ University of Pittsburgh Medical Center, Pittsburgh, United States,

⁵ Semmes Murphey Clinic, Memphis, United States,

⁶ University of Columbia, New York, United States,

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

Introduction: The purpose of this study was to identify differences in intraoperative neurophysiological monitoring (IOM) event rates between SP lateral decubitus and prone-lateral patients during spine surgery. Material and Methods: Patients were stratified by operative positioning: Lateral decubitus (LD) and Prone Lateral (PL). IOM was performed using somatosensory evoked potentials (SSEPs), motor evoked potentials (MEPs), and electromyography (EMG) techniques. An abnormal event was defined as any confirmed loss of signal during the operative period in the anatomical distribution of the surgery. Means comparison tests and multivariable logistic regression analysis assessed differences between patient groups. Results: 152 met inclusion criteria (93 LD & 59 PL). The majority were male (55.7%), mean age of 49.2 yrs and 2.0 levels fused and 18 (20.5%) undergoing an osteotomy. There was a significant difference in abnormal IOM event rates for patients who were in Lat (31%) vs PL (8%) positioning, p = 0.012. Multivariable analysis revealed that PL patients were less likely to experience an abnormal IOM event than Lat patients (OR 0.232 [CI 0.060-0.905], p = 0.035). This was seen in the saphenous, quadriceps and perineal sensory distributions. Conclusion: Prone lateral positioning offers advantages over lateral decubitus with regards to decreased abnormal intraoperative neurophysiological events. This may potentially help with risk stratification in the future when assessing patients undergoing single position procedures.

ID: 1541

A278: Awake surgery versus general anesthesia in minimal invasive lumbar spine procedures: a multicenter prospective comparative trial

Arthur André ^1,2 , Malaize Henri ³ , Brice Edouard ¹ , Antoine Kourilsky ¹ , Nadia Bezaz ¹ , Michael Ohana ¹ , Vincent Degos ² , Carpentier Alexandre ³

¹ Ramsay Sante, Hopital Geoffroy Saint Hilaire , Paris, France,

² Greater Paris Hospitals, Pitié-Salpêtrière Hospital, Anesthesiology, Paris, France,

³ Greater Paris Hospitals, Pitié-Salpêtrière Hospital, Neurosurgery, Paris, France

Introduction: Spine surgery has lastly benefited from minimally invasive surgery (MIS) techniques (MIS) and enhanced recovery after surgery (ERAS) protocols. We developed an awake microsurgery technique combining those advances. The aim of this study was to compare our method to the standard of care (SOC) with conventional management for simple lumbar decompression, disc herniation or 1 level Arthrodesis. Material and Methods: We conducted a comparative multi centric prospective trial, enrolling 99 patients in Paris, France. Patients Quality of Life (QOL), pain, walking distance, and anxiety were assessed preoperatively, at 1 Day and 1 month postoperatively. Clinical examination, surgery duration and length of stay at the hospital were also recorded. Surgery success was defined by an improvement of QOL for more than 30%. Results: QOL was significantly better in the ERAS group compared to SOC at 1 month (75% vs 45% of success). Mean pain was lower at day 1 (1.8 vs 5.5) and at 1 month (1.0 vs 2.3). Length of stay, analgesic drug consumption, and postoperative anxiety were also significantly lower in the ERAS group. There was no difference in terms of walking distance, neurologic deficit, or complications. Conclusion: Awake MIS appears to be safe and more efficient than conventional techniques in the early postoperative period, improving patient short term outcome and experience.

ID: 1028

A279: Relationship between disc height, segmental lordosis and indirect decompression in minimally invasive anterior and lateral lumbar interbody fusion

Jorge Luis Alejandre-Lopez ¹ , Carlos Razo Vite ¹ , Apolinar De La Luz Laguna ¹ , Gilfredo Gonzalez-Basile ²

¹ Centro Medico Nacional 20 de Noviembre, Neurosurgery, Column Surgery, Mexico, Mexico,

² Hospital Angeles Pedregal, Column Surgery, Mexico, Mexico

Introduction: Interbody fusion procedures are an accepted and successful treatment strategy to relieve pain and/or neurological symptoms associated with degenerative spondylolisthesis of the lumbar spine. Symptoms of radiculopathy and neurological claudication may also be alleviated indirectly through restoration of intervertebral and foraminal heights and correction of spinal alignment. The aim of the current study was to know the clinical (ODI) and radiographic impact (lumbar lordosis, disc height and segmental lordosis) in patient treated with LLIF and ALIF, measure indirect neural foraminal decompression in surgically operated patients using radiographic measurement and elucidate factors affecting foraminal restoration. Material and Methods: Retrospective, descriptive, single-center study from 2021 to 2023, in patients treated with LLIF and ALIF in CMN November 20, for degenerative lumbar pathology, without history of spine surgery, 1 or 2 levels was performed, Measurement of ODI PRE and POST at 6 months, radiological values (disc height, lumbar lordosis, segmental lordosis and foraminal area) were measured using Surgimap software. Results: Selection of 33 patients (15 LLIF and 16 ALIF), a median age of 60 years (±11.92). All LLIF were performed for levels L4-L5, 2 of this patient were performed a second level for L3-L4. All ALIF were performed for levels L5-S1. A PRE ODI of 67.11% (±11.05) was found with an ODI improvement at 6 months of 32.44% (±11.22). We observe in radiographic measurements an improved in LLIF and ALIF with increase disc height up to 5.65 mm and 5.78 mm, lumbar lordosis 3.17° and 4.26°, and segmental lordosis in 4.94° and 5.18° respectively. LLIF and ALIF resulted in a statistically significant (p < .01) improvement in foraminal area 30.6% and 55.2% respectively. The mean foraminal area increased from 99.2 mm in LLIF and 92.7 mm in ALIF preoperatively to 134.3 mm and 147.2 mm postoperatively (p < 0.001) respectively. Multivariate regression analysis demonstrated that the disc height was the only independent factor that correlated with the increase forminal area. Conclusion: LLIF and ALIF improves ODI at 6 months, with improvement in radiographic parameters such as lumbar lordosis, segmental lordosis and disc height. The LLIF and ALIF provides the necessary decompression. The disc height is a significant factor in the restoration of the foraminal area.

OP32: Cervical Deformity 2

ID: 1852

A280: Does the addition of a foraminotomy impact outcomes following multi-level PCDF for myeloradiculopathy?

Robert Oris ¹ , Jonathan Dalton ¹ , Rajkishen Narayanan ¹ , Tariq Issa ¹ , Michael Carter ¹ , Joydeep Baidya ¹ , Chloe Herczeg ¹ , Rachel Huang ¹ , Jarod Olson ¹ , Jonah Hammerstedt ¹ , Jose Canseco ¹ , Alan Hilibrand ¹ , Alex Vaccaro ¹ , Chris Kepler ¹ , Gregory Schroeder ¹

¹ Rothman Orthopaedics, Philadelphia, United States

Introduction: As the United States population continues to age, the incidence of cervical spine degenerative disease, including myelopathy, is expected to increase. For cervical degenerative disease, the optimal surgical approach remains controversial, especially in the setting of multilevel involvement. To address cervical myelopathy, posterior cervical decompression and fusion (PCDF) decompresses the central canal and provides stability to prevent post-laminectomy kyphosis. However, isolated PCDF may not adequately address concomitant radiculopathy due to neural foraminal compression. Conversely, a posterior cervical foraminotomy alone only addresses neural foraminal compression by expanding the neural foramen and providing indirect nerve root decompression. In the setting of cervical myeloradiculopathy, wherein patients demonstrate clinical symptoms of both pathologies, posterior approaches must address both sources of compression. Despite this, it is unclear if multi-level PCDF in the absence of intentional foraminotomy provides adequate indirect foraminal decompression. Therefore, the objective of this study was to evaluate whether patients with myeloradiculopathy experience better improvement in patient-reported outcomes (PROs) from addition of foraminotomy in the setting of PCDF. Methods: The final cohort included all adult patients who underwent 3+ level PCDF between 2017-2022 for myelopathy, had at least one complete 1-year PRO measure, and had preoperative documentation of arm pain, numbness, or weakness suggesting radiculopathy. Patients were classified as having a foraminotomy for foraminal decompression based on documentation in the op note. Patients who had a small foraminotomy only for the purpose of identifying the pedicle or relevant anatomy, rather than for foraminal decompression, were placed in the “No” group. Groups were compared based on baseline patient and surgical variables, surgical outcomes, and PROs at baseline and 1 year postoperatively. Results: A total of 36 patients had a foraminotomy while 71 did not. Age, sex, BMI, CCI, smoking status, race, and number of levels fused were similar between groups. Groups were similar regarding operating room time, cut-to-close time, length of stay, estimated blood loss, readmissions, or discharge disposition. Modified Japanese Orthopedic Association (mJOA), SF-12 PCS and MCS, NDI, and VAS neck scores were similar between groups. The foraminotomy group experienced higher baseline (5.56 ± 2.63 vs. 4.00 ± 2.69, p = 0.015) as well as greater improvement in VAS arm scores (-2.99 ± 3.22 vs. -1.25 ± 3.06, p = 0.035). Conclusion: Patients who had a foraminotomy experienced greater improvement in arm pain at 1-year follow-up without an increase in surgical time, hospital stay, or complications. The present study suggests that, for the appropriately selected patient with myeloradiculopathy undergoing multi-level PCDF, performing intentional foraminal decompression leads to improved outcomes without altering surgical morbidity or in-hospital resource utilization.

ID: 1522

A281: Cervical paraspinal muscles quality in orthopedic dropped head patients: a propensity score matching

Bruno Verna ¹ , Thomas Caffard1 ² , artine arzani ¹ , Lukas Schönnagel ³ , Ali Guven ¹ , Krizia Amoroso ¹ , Erika Chiapparelli ¹ , Ranqing Lan ⁴ , Jennifer Shue ¹ , Andrew Sama ¹ , Federico Girardi ¹ , Frank Cammisa 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, Biostatistics Core, New York, United States

Introduction: Dropped Head Syndrome (DHS) manifests as severe weakness in the cervical paraspinal muscles, leading to progressive sagging of the head and the distinctive chin-on-chest deformity marked by pronounced kyphotic curvature of the cervico-thoracic spine. DHS has various etiologies, with two theories focusing on the involvement of the paraspinal musculature: 1) excessive anterior cervical muscle tone overpowers the posterior cervical spine extensors, leading to neck flexion, and 2) primary weakness and/or atrophy of the posterior cervical musculature contributes to the syndrome. To the best of our knowledge, there is no literature analyzing the muscle fat infiltration (FI) of every subaxial level in orthopedic DHS patients. Our study aims to examine the cervical paraspinal musculature and assess differences in FI among patients with DHS, patients that underwent 1-2 level ACDF, and those undergoing multi-level ACDF. Material and Methods: Patients with orthopedic DHS were recruited. All patients demonstrated a chin-on-chest deformity. Patients with neurodegenerative conditions were excluded. Muscles from C3-C7 were categorized into 6 functional groups: sternocleidomastoid group (SCM), anterior group (AG), posteromedial (PM), posterolateral group (PL), scalenus group (SN) and trapezius group (TP). Muscle segmentation was performed using a dedicated software. After the muscles were segmented, a custom written software used to calculate the cross-sectional area (CSA), functional CSA (fCSA), and percent FI. Propensity score matching was performed adjusting for age, sex and BMI. The propensity score matching was performed on a dataset of 201 patients undergoing ACDF. The Kruskal-Walli’s test was used to test for significant differences among the three groups. For pairwise comparisons, Mann-Whitney tests with Bonferroni correction were conducted. Results: A total of 22 patients with orthopedic DHS were recruited (median age 71.5 years: 40.91% females). The propensity score analysis matched 22 1 or 2-level ADCF patients and 22 > 3 level ACDF patients. Statistical significance was set at a p-value of 0.05. At every level analyzed, differences were found among the 3 patient groups for the majority of the groups, being the extensors muscle groups the most significant ones. From C3 to C7, the DHS showed a significantly greater FI of the PL group compared to both ACDF patient cohorts. From C4 to C6, the DHS cohort showed a significantly greater FI of the PM group compared to both ACDF patient cohorts. Conclusion: To the best of our knowledge, this is the first study to quantify the FI in the different cervical muscle groups in DHS patients compared ACDF patients. Our findings reveal a higher FI in the DHS group compared to the ACDF group, supporting the hypothesis that cervical musculature is implicated in the pathology. Major significant results were found in the PM and PL groups, both which encompass the extensor cervical musculature that is believed to be the most involved in the development of DHS. Increased FI correlates with poorer post-surgical outcomes, negative patient-reported outcomes, and decreased quality of life. This highlights the necessity of adopting more integrative approaches to patient care and emphasizes the potential benefits of muscle training therapy prior to surgical intervention.

ID: 665

A282: Perioperative outcomes, technical and patient reported success of rigid occipitocervical (OC) fusions: a systematic review and meta-analysis of 1247 patients

Alexander Aguirre ¹ , Isabelle Stockman ² , Mohamed Soliman ¹ , Esteban Quiceno Restrepo ¹ , Asham Khan ¹ , Kyungduk Rho ¹ , Jacob Greisman ¹ , 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: Occipitocervical (OC) fusions are uncommon and challenging surgeries as patients present with a wide range of pathologies. Due to its rarity limited outcome data has been available for OC fusions. To the authors’ knowledge, this is the first meta-analysis on the topic of OC fusions, now with specific focus on the current preference of treatment focusing on rigid constructs. Material and Methods: A literature search of the Embase and MEDLINE databases was completed, studies were included if they focused on rigid construct methods for OC fusions. Meta-analysis was completed adhering to the random effects models, where continuous variables were analyzed with pooled-weighted means (95% confidence intervals [CI]), and categorical variables with pooled-weighted prevalence rates (CI). Results: A total of 42 studies encompassing 1247 patients were included in this study. Included patients had a mean age of 57.18 (CI, 52.21-62.15; I 2 = 94.47%) with males presenting 42.77% (CI, 35.97-49.86; I 2 = 53%) of the time. Successful bony fusion was found in 96.72% (CI, 92.54-98.59; I 2 = 0%) of cases, with reoperation occurring in 4.72% (CI, 2.62-8.36; I 2 = 0%) of patients. Surgical site infection was the most common complication at a rate of 6.97% (CI, 5.19-9.29; I 2 = 0%), followed by cerebral spinal fluid leak 2.93% (CI, 1.32-6.36; I 2 = 0%), instrumentation failure 2.60% (CI, 1.16-5.71; I 2 = 0%), vertebral artery injury 1.64% (CI, 0.74-3.61; I 2 = 0%), and screw loosening 1.44% (CI, 0.65-3.16; I 2 = 0%). Conclusion: Rigid OC fusions demonstrate an extremely high likelihood of successful bony fusion, and lower rates of complications than previously published demonstrating a promising current state and future of OC fusion.

ID: 672

A283: Tomographic morphometric analysis of the subaxial cervical pedicles for minimally invasive fixation techniques

Mohamed Soliman ¹ , Jacob Greisman ¹ , Esteban Quiceno Restrepo ¹ , Ryan Hess ¹ , Alexander Fritz ¹ , Asham Khan ¹ , Isabelle Stockman ² , Hendrick Francois ² , Shashwat Shah ² , Benard Okai ² , Deanna Chan ² , Joseph St. Onge 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: Cervical pedicle screw fixation offers significant biomechanical advantages, yet its adoption is constrained by concerns about potential complications, particularly vertebral artery injury. While minimally invasive techniques have been explored, their widespread utilization remains limited. This study's primary aim was to elucidate the morphological characteristics of cervical pedicles and assess the optimal trajectories and entry points for instrumenting the cervical spine, taking into consideration minimally invasive and transmuscular techniques. Material and Methods: Cervical CT scans were performed on consecutive patients using a Philips Ingenuity 128-slice scanner (Ingenuity Core 128, Philips Healthcare). A total of 91 patient scans were analyzed, encompassing measurements of pedicle width, height, screw length, transverse angle, and trajectory parameters. Results: The pedicle width, pedicle height, and screw length progressively increased from C3 to C7. Males had significantly larger pedicles and longer screw lengths than women (p < 0.05). The pedicle transverse angle was widest at C4 (54.2 ± -3.5) and narrowest at C7 (43.5 ± 4.7), with a statistically significant difference between levels (p < 0.001). The ideal starting point for a percutaneous approach ranged from 68.2 ± 9.6 mm at C7 to 74.5 ± 13.7 mm at C4. A strong positive correlation was found between higher BMI and larger distances (r: 0.67). The canal-vertebral angle showed a progressive decrease from C3 to C7, ranging from 56.2 ± 7.6 to 50.8 ± 10.5. The pedicle facet angle and the distance from the inferior tip of the inferior articular process to the ideal starting point increased progressively from C3 to C7, with a statistically significant difference between levels (p < 0.05). Conclusion: This study provides comprehensive insights into the morphological characteristics of cervical pedicles and optimal trajectories for safe screw instrumentation. The findings are in harmony with existing literature, offering valuable guidance for the safer and more accurate placement of cervical pedicle screws.

ID: 2919

A284: Influence of upper cervical malalignment and negative sagittal imbalance on clinical outcomes in patients with craniovertebral juncion kyphosis

Jae Taek Hong ¹

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

Introduction: This study aims to identify the possible prognostic factors for the craniocervical realignment procedure for CVJ kyphosis combined with negative sagittal imbalance, to determine the critical value of radiological parameters for predicting good surgical outcome, and to establish a radiological standard for reducing the CVJ kyphosis. Methods: This retrospective study underwent a craniocervical realignment procedure in patients with CVJ kyphosis and negative sagittal imbalance between January 2014 and November 2022. A total of 27 consecutive patients with CVJ kyphosis and negative cervical imbalance who underwent craniocervical realignment surgery were enrolled. The inclusion criteria were as follows: 1. The patient with a C0-C2 angle less than 0 degree. 2. The C2-C7 sagittal vertical axis (SVA) is less than 0 mm. 3. No previous history of cervical spinal surgery, cervical trauma, syrinx, tumor, or infection. 4. Minimum of one-year follow-up after surgery. The C0-C2 Cobb angle, C0-2 ROM, C2-C7 Cobb angle, C2-7 ROM, the C7 sagittal vertical axis (SVA), C2-7 SVA, C2-slope, C7-slope, thoracic kyphosis (TK), pelvic incidence (PI), and lumbar lordosis (LL) were measured before and one year after surgery. The Japanese Orthopaedic Association (JOA) score was used to determine the neurological outcome. Axial symptom severity was quantified by Neck Disability Index (NDI, 0 = no disability, 50 = total disability) and visual analog scale (VAS). Patients were divided into two groups according to their recovery rate (RR) for neurologic function. Patients with RR of > 50% and < 50% were designated as having good and poor outcomes, respectively. We also divided patients into two groups based on the improvement of NDI; good (NDI improvement > 10) and poor (NDI improvement < 10). The relationship between various possible prognostic factors and clinical outcomes were assessed by univariate and multivariate analysis. Results: A total of 27 consecutive patients with CVJ kyphosis and negative cervical imbalance who underwent craniocervical realignment surgery were enrolled (M/F = 6/21, The mean age = 57.1 ± 17.3 years). The patient mean age, gender, radiological and clinical parameters were similar between the two groups (p > 0.05), respectively. Postoperative cervical radiological parameters (C02 angle, C27 angle, C2 slope, C27 SVA, and cervical ROM) changed significantly (p < 0.001). However, there were no significant postoperative changes regarding the TK, LL, PI, and C7 SVA. Between the two JOA RR groups, the C02 angle change (12.7 vs 7.5, p = 0.042) and the C27 SVA change (18.8 vs. 5.1, p = 0.000) had significant differences. There were also significant differences between the two NDI groups in the C02 angle change (15.7 vs. 7.1, p = 0.000) and C27 SVA change (20.2 vs 9.3, p = 0.002). Multivariate regression analysis showed that C02 angle change was independently associated with NDI improvement (p < 0.01). Follow-up data analysis showed significant differences (P < 0.001) in the C02 angle, C27 angle, C2 slope, and C27 SVA, whereas no significant differences in C7 SVA, TK, LL, and PI. There was significant relaxation of the C2-C7 angle (p < 0.01) after surgery with significant improvement in cervical alignment, which positively correlated with the magnitude of CVJ deformity correction. C0-2 angle and C2-C7 SVA negatively correlated with NDI scores (r = -0.275 and r = -0.399, respectively). C2-C7 SVA was positively correlated with the JOA score (r = 0.241). Of 25 total patients, eighteen were classified as favorable NDI outcome group (postoperative NDI < 10), while the remaining seven patients achieved unfavorable outcomes (postoperative NDI > 10). Patients with favorable NDI outcomes had a significantly higher increase in C0-C2 (p = 0.042) and a higher increase in C2-C7 SVA (p = 0.000). C0-2 angle change significantly correlated with the correction of negative sagittal imbalance (ΔC2-7 SVA, p = 0.037) after surgery. Improvements in NDI scores significantly correlated with the correction of CVJ Kyphosis (ΔC0-C2 angle, p = 0.002) & negative imbalance (ΔC2-7 SVA, p = 0.003) after surgery. JOA RR significantly correlated with the correction of negative sagittal imbalance (ΔC2-7 SVA, p = 0.001) after surgery. Conclusions: Craniocervical realignment surgery improved the neurological function and quality of life of patients with CVJ kyphosis. The most critical radiological parameter for predicting good outcomes is the postoperative improvement of the C02 angle and C27 SVA. The C02 angle is the most significant independent parameter to predict the improvement of axial neck pain. Following surgical treatment of CVJ kyphosis, lower cervical compensation relaxed, negative sagittal imbalance improved, and NDI decreased. Our findings suggest that it is essential for clinical recovery to restore CVJ alignment and sagittal balance.

ID: 630

A285: Reduction of C2 slope as an indicator of adequate postoperative thoracolumbar deformity correction

Alexander Aguirre ¹ , Hendrick Francois ² , Esteban Quiceno Restrepo ¹ , Mohamed Soliman ¹ , Isabelle Stockman ² , Benard Okai ² , Shashwat Shah ² , Joseph St. Onge ² , Deanna Chan ² , Jacob Greisman ¹ , Asham Khan ¹ , 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: There is a limited body of research examining the changes in cervical parameters following thoracolumbar deformity correction surgery. This study seeks to explore modifications in cervical parameters following the successful surgical correction of thoracolumbar deformity in patients who do not have concomitant fixed cervical deformities. The objective of our study was to determine the impact of thoracolumbar surgery on the C2 slope. Material and Methods: We performed a retrospective analysis involving 122 consecutive patients who underwent surgery for severe thoracolumbar deformities. Patients who achieved favorable postoperative thoracolumbar and spinopelvic radiographic outcomes were included in the analysis. Preoperative and postoperative cervical parameters were measured and compared. Statistical analysis utilized Student’s t-test and Pearson's coefficient. Results: Out of the 122 patients, 78 achieved postoperative sagittal vertical axis (SVA) below 10 cm, pelvic tilt (PT) less than 20°, and lumbar mismatch within 5-15, indicating favorable radiographic outcomes. Analysis of various cervical parameters within these patients did not reveal any significant differences in preoperative and postoperative C1-C2 angle, C2-C7 angle, or the cervical sagittal vertical axis (cSVA). However, when assessed using a Pearson correlation coefficient, only the C2 Slope exhibited a strong positive correlation (r > 0.7) within successful radiographic cases (p < 0.001). Additionally, the mean reduction in the C2 slope was 13° (±7) among all patients who did not meet criteria for fixed cervical deformity and achieved successful thoracolumbar radiographic outcomes, with a p-value of 0.008. Conclusion: Cervical parameters exhibit changes after thoracolumbar deformity correction surgery. In patients without concurrent fixed cervical deformities, cervical spine lordosis becomes one of the primary mechanisms for maintaining horizontal gaze. The most significant compensatory radiographic parameter observed is the C2 Slope, which tends to decrease following successful thoracolumbar corrective deformity surgery. This reduction in the C2 Slope can be considered an indicator of adequate postoperative correction in the absence of cervical deformity.

ID: 1536

A286: Management strategies in irreducible atlantoaxial dislocation

Sudhir Srivastava ¹ , Sunil Bhosale ²

¹ K.J Somaiya Medical College and Research Centre, Orthopedics, Mumbai, India

² Seth G.S Medical College and KEM Hospital, Orthopedics, Mumbai, India

Introduction: Management of irreducible atlantoaxial dislocation (IAAD) more so with the component of basilar invagination (BI) has been challenging. Posterior decompression and fixation, anterior odontoidectomy and posterior joint distraction technique has been described. In 2006 Wang et al. described that by doing anterior release IAAD can be converted into reducible AAD. We present our algorithm of managing IAAD. Material and Methods: It is a retrospective study of 48 patients of IAAD [41 congenital, 7 acquired (Tuberculosis - 4, neglected trauma - 1, rheumatoid - 2), 30 out of 48 patients had BI] treated from 2007 to 2021. All patients had neurological deficit. Preoperative mJOA score and CCA (clivus canal angle) was measured. Reducibility of dislocation was assessed by dynamic X-ray. Patients were put on skeletal traction in the ward and reducibility was checked. Reducibility was also checked under anesthesia. IAAD were taken for anterior release [transoral (TO) – 12 cases, Retropharyngeal - 36 cases] where longus colli, longus capitis and anterior longitudinal ligaments were cut, joint capsule was opened and lateral joints were made supple. Under supervision patient was turned prone on head rest and posterior fixation with fusion was done. In cases of occipitalised Atlas, fixation and fusion was done from occiput to C3. C1-C2 transarticular fixation was done in 4 patients, C1- C2 separate screw fixation in 8 patients, OC (Occipitocervical) fusion in 36 patients. There were 41 males and 7 females. Results: 40 patients had full reduction while 8 patients had partial reduction. The mJOA improved from mean preoperative 10.89 to mean postoperative 16.82. Mean preoperative CCA of 110.4 improved to mean postoperative CCA of 146.4. Maceration of posterior wound occurred in 4 patients which healed by daily cleaning and dressing. Implant breakage on one side was noted after 3 months postoperative in one patient who remained asymptomatic. In a pediatric patient occipital plate backed out at 8 weeks. It was reexplored and plate was fixed to occiput with sublaminar wire. Fusion was achieved in all patients. Conclusion: Pre and intraoperative traction, single stage anterior release and posterior instrumented fusion in IAAD gives desirable clinico-radiological outcome.

ID: 1140

A287: Evaluating the learning curve of reliably placing sub-axial pedicle screws without navigation

Cameron Hogsett ¹ , Paul Waldrop ¹ , Michael Wade ² , Wesley Miaw ² , Cezar Sandu ¹

¹ John Peter Smith Hospital, Orthopaedic Surgery, Fort Worth, United States

² Texas College of Osteopathic Medicine, Fort Worth, United States

Introduction: Several surgical techniques have developed over the years for stabilization of the cervical spine such as spinous process and sublaminar wiring, lateral mass screws, translaminar screws, facet screws, and pedicle screws. Of these techniques, cervical pedicle screw (CPS) fixation provides early stability and increased biomechanical support to achieve superior spinal stabilization. Although CPS fixation provides known superior biomechanical strength than other techniques, the anatomic complexity of the pedicle and its adjacent structures, risk of complications, and inherently challenging application of proper screw placement limit its use clinically. Recently, Liu et al. published promising results of placing cervical pedicle screws in vivo at levels 3-7 free hand without navigation using their novel “medial slide technique”, reported as reliable and safe in select patients without the use of navigation and minimal fluoroscopy. Our study aims to replicate this technique with junior and senior orthopaedic surgery residents in cadavers to evaluate its reliability, safety, and ultimately feasibility in practice. Material and Methods: Specimens underwent preoperative three-dimensional computed tomography (3D-CT; 1mm slices) of the cervical spine to evaluate anatomic integrity and exclude structural abnormalities such as pedicle atresia or defects, sclerosis, or presence of previous hardware. Orthopedic surgery residents, one junior and one senior level, placed pedicle screws at spinal level C3-C7 on 20 different male and female cadavers. Alternating left and right orientation, 100 pedicle screws of 24mm length and 3.5 mm diameter were placed per resident. The screw pathway was created using the medial slide technique without navigation as described by Liu et al. For every cervical segment, the surgeon self-reported a confidence level of “low”, “medium”, or “high”, predicting the accuracy of the screw placement based on the initial feel of each pedicle probe pass and ball tipped probe feedback. 3D-CT was re-utilized to evaluate screw placement, graded blindly and separately using the Gertzbein-Robbins classification by two examiners. Learning curve cumulative summation (LC-CUSUM) was used to establish resident competency of the technique. Results: Confidence was significantly associated with successful screw placement (p = 0.003). A high level of confidence led to a 26% increase in the odds of success (α = 0.5%), compared to low confidence. LC-CUSUM showed the senior level resident achieved competency by the 22^nd screw, while the junior level resident did not achieve competency within this sample size. The medial slide technique was precise and accurate for levels C3-5 but eventually required a start point change for the C6-7 levels and adjustment of the medialization angulation of 30-35 degrees. Adapting the starting point of the medial slide technique to better accommodate spinal levels C6 and C7 allowed for more successful screw placement. Conclusion: We propose a more reliable pedicle screw start point for the C6-7 levels using the “medial slide technique” along with new exclusion/inclusion criteria that optimize the safety of placing sub-axial cervical pedicle screws without navigation. With our findings, we believe the learning curve proves to be achievable with the proposed starting points and technique along with careful patient selection.

ID: 2642

A288: Refining preoperative classification of irreducible atlantoaxial dislocation based on intraoperative reduction difficulity

Jing Xu ¹ , Shaodong Mo ¹ , Bailiang Liu ¹ , Fuzhi Ai ¹

¹ Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Department of Orthopedics, Guangzhou, China

Introduction: Traditional management of irreducible atlantoaxial dislocation (IAAD) often involved transoral release/decompression techniques. However, recent developments in posterior-only surgical approaches have demonstrated their efficacy in managing most IAAD cases, thereby minimizing the complications of transoral interventions. This progress calls for an update in the classification of IAAD. Building on our substantial collection of IAAD cases treated with the transoral stepwise release technique--which categorized reduction difficulties based on its procedural steps--this research aims to develop a preoperative predictive model to differentiate between mild and severe IAAD cases, assessing their potential for reduction via posterior-only approaches. Material and Methods: We conducted a retrospective analysis of IAAD cases managed with the transoral stepwise release technique, classifying patients into Grades I-IV based on reduction difficulty: Grade I (mild), Grades II-III (severe), and Grade IV (bony dislocation). We compared clinical characteristics and craniocervical deformities between severe and mild IAAD groups. Using feature engineering, we developed a predictive model to distinguish between mild and severe irreducible dislocations. The model’s clinical utility was validated by assessing its role in guiding the choice between posterior-only and transoral approaches for different IAAD categories. Results: Key predictors of severe IAAD included Chiari malformation, specific osteophyte formations, and joint deformities. The predictive model, integrating nine variables, demonstrated an accuracy of 80.54% in the training set and 75.00% in the testing set. Clinical validation with 37 patients confirmed the model’s effectiveness in guiding surgical decision-making, showing comparable outcomes in postoperative atlantoaxial reduction rates and improvements in Japanese Orthopaedic Association (JOA) scores across treatment groups. Conclusion: This study refines IAAD classification and introduces a predictive model that enhances surgical strategy planning. The model’s practical utility in clinical settings supports more precise decision-making for managing IAAD, optimizing patient outcomes.

OP33: Cervical Trauma Surgery 2

ID: 2298

A289: The sodium-glutamate antagonist riluzole improves outcomes after acute spinal cord injury: results from the RISCIS randomized controlled trial using a global statistical analytic technique

Karlo Pedro ¹ , Mohammed Ali Alvi ¹ , James Harrop ² , Ralph Stanford ³ , James Guest ⁴ , Bizhan Aarabi ⁵ , Michael Fehlings ^1,6

¹ University of Toronto, Toronto, Canada,

² Thomas Jefferson University, Philadelphia, United States,

³ Prince of Wales Hospital, Sydney, Australia,

⁴ University of Miami, Miami, United States,

⁵ University of Maryland, Baltimore, United States,

⁶ University Health Network, Division of Neurosurgery, Toronto, Canada

Introduction: Clinical trials in spinal cord injury (SCI) often rely on a single primary endpoint to assess drug efficacy. However, this may not fully capture the true impact of interventions, especially in heterogeneous conditions like SCI. To comprehensively evaluate outcomes, it is crucial to concurrently consider neurological function, functional capacity, and quality of life, thereby incorporating meaningful patient-reported endpoints. Contemporary statistical methods, like the global statistical test (GST), address this by testing multiple trial endpoints. This study aims to investigate the applicability and advantage of the GST framework using data from the RISCIS (Safety and Efficacy of Riluzole in Acute Spinal Cord Injury Study) trial. Materials and Methods: The RISCIS trial included patients with cervical traumatic SCI and American Spinal Injury Association Impairment Scale (AIS) grades A to C, occurring within 12 hours of injury. Patients were randomly assigned to receive either riluzole or placebo. Riluzole was administered at 100 mg orally twice daily (BID) for the first 24 hours, followed by 50 mg BID for the subsequent 13 days. We applied a multivariable nonparametric GST that integrates the ASIA motor score (TOTM), Spinal Cord Independence Measure (SCIM), and SF-36 PCS (Short Form-36) scores. Six-month outcomes were compared using a modified O’Brien’s rank sum test with sample variance adjustment. Higher summed ranks indicate better global outcome. The overall probability of improvement was computed using the global treatment effect (GTE). Results: A total of 131 patients with a mean age of 45.82 years old (81.7% males, 18.3% females) had complete outcome assessment at 6 months. Among these, 49.6% were classified as ASIA A, 20.6% as ASIA B, 29% as ASIA C, and 0.8% as ASIA D. Riluzole was administered within 12 hrs from injury for a total duration of 14 days in 65 patients, while 66 received placebo drug. The individual unadjusted mean change from baseline to 6 months suggests a favorable response in the riluzole group compared to placebo using TOTM (p = 0.95 by t-test; p = 0.29 by Wilcoxon test,), SCIM (p = 0.36 by t-test; p = 0.09 by Wilcoxon test), or SF-36 PCS (p = 0.15 by t-test; p = 0.14 by Wilcoxon test) scores. Using the GST to simultaneously assess TOTM, SCIM, and SF-36 PCS, a higher rank sum was observed in the riluzole group compared to placebo [median rank sum (IQR) = 207 (166-246) in riluzole vs 185.20 (146-236) in placebo, p = 0.04). Subgroup analysis revealed the greatest treatment benefit among ASIA A patients (GTE = 0.16, p = 0.02). At 6 months, riluzole treatment was associated with a 55% higher probability of global improvement compared to placebo. Conclusions: Riluzole was associated with a favorable global outcome in severe traumatic SCI patients, based on a composite score combining ASIA total motor scores, SCIM and SF36 outcomes at six months. The multidimensional approach to outcome assessment could enhance the power of detecting beneficial treatment effects in SCI trial and should be considered in future studies. Clinicians may consider using riluzole in acute SCI patients to optimize outcomes based on the available data.

ID: 2300

A290: The influence of fracture status in determining the effectiveness of surgical intervention in central cord syndrome

Karlo Pedro ¹ , Mohammed Ali Alvi ¹ , Michael Fehlings ^1,2

¹ University of Toronto, Toronto, Canada,

² University Health Network, Toronto, Canada

Introduction: Central Cord Syndrome (CCS) is the most common form of incomplete spinal cord injury (SCI), predominantly affecting elderly individuals after low-level falls. For CCS with fracture and instability (CCS-F), prompt surgical decompression and stabilization are well-established strategies to optimize neurological recovery. In contrast, the management of CCS resulting from spondylosis without associated bony injuries (CCS-S) remains controversial. A common practice involves an initial non-operative intervention until spontaneous recovery occurs, or delaying surgery until a neurological plateau is reached. This conservative approach, originating from early CCS descriptions, lacks robust evidence, with studies yielding conflicting results. The heterogenous nature of CCS, driven by variations in injury mechanisms and definitions, suggests that this strategy may not be universally suitable for all patients. This study aims to compare surgical versus non-operative interventions in both CCS-S and CCS-F patients, utilizing consistent diagnostic criteria and adjusted analyses from a large cohort of SCI patients. Materials and Methods: This ambispective study analyzed data from five multicenter SCI studies (NASCIS III, Sygen Trial, STASCIS, NACTN, and RISCIS), comprising 2,583 patients. CCS was defined by a ≥ 5-point difference between ASIA lower and upper extremity motor score (LEMS – UEMS ≥ 5) and an ASIA grade of C or D. Patients were stratified into CCS-F (with fracture) and CCS-S (stable). Propensity score-matching was employed to adjust for age, injury mechanism, neurological level, total motor score, and ASIA grade. Neurological outcomes were assessed using LEMS, UEMS, and ASIA total motor score (AMS), while functional outcome was measured using the Functional Independence Measure (FIM). We evaluated changes at one year and the proportion achieving the minimum clinically important difference (MCID). Multivariable regression analysis, including an interaction term for surgery and fracture status, identified independent predictors of functional recovery. Results: A total of 291 CCS patients were included, of which 246 (84.5%) were male. Of these, 205 (70%) underwent surgery, while 86 (30%) received non-operative treatment. At one-year follow-up, a significantly higher proportion of patients in the surgical group achieved the FIM-Motor MCID (57.1%) compared to the non-surgical cohort (41.9%) (p = 0.018). Stratified analysis showed that surgery was mainly beneficial for CCS-S patients, with 66.7% achieving MCID versus 34.2% in the non-surgical subgroup (p < 0.001). In contrast, among patients with CCS-F, there was no significant difference in outcomes between the surgical and non-surgical groups (MCID achievers = 49.1 vs 47.9%, p = 0.890). In the propensity-matched cohort, CCS-S patients demonstrated greater benefit from surgery than CCS-F patients. Surgery significantly increased the odds of achieving favorable functional outcomes (OR 2.83, 95% CI 1.23-6.56) compared to non-operative treatment. However, after adjusting for the presence of fractures, the odds of improvement decreased substantially (p value for interaction = 0.04, OR 0.32, 95% CI, 0.11-0.98), suggesting that fracture status modifies the impact of surgery on outcomes. Conclusion: Surgical intervention significantly improved functional outcome at one-year compared to conservative management in CCS patients, with particularly pronounced benefits in the CCS-S subgroup. This underscores the need for individualized treatment strategies tailored to specific patient characteristics in managing CCS.

ID: 1122

A291: Comparative validation of scoring systems using machine learning in acute traumatic central cord syndrome: a multi-ethnic study of ATCCSS, CCScore, and subaxial AOSIS for functional and motor recovery

A Aravin Kumar ¹ , Linda Lim Huiling ¹ , Zhiquan Damian Lee ¹ , Lester Lee ¹ , Dinesh Shree Kumar ² , Robin Pillay ¹ , Ji Min Ling ¹

¹ National Neuroscience Institute, Department of Neurosurgery, Singapore, Singapore,

² Changi General Hospital, Department of Orthopaedic Surgery, Singapore, Singapore

Introduction: Acute traumatic central cord syndrome (ATCCS) is the most common form of incomplete spinal cord injury. Treatment recommendations for ATCCS patients largely emerge from North American studies, and their applicability to Asian populations remains uncertain. Scoring systems and classification scales, such as the Central Cord Score (CCScore), Acute Traumatic Central Cord Syndrome Score (ATCCSS), and Subaxial AO Spine Injury Score (Subaxial AOSIS), are increasingly used to guide treatment, standardize practice, and improve outcomes. This study aims to validate and compare the predictive capabilities of ATCCSS, CCScore, and Subaxial AOSIS in a multi-ethnic Southeast Asian population, with a focus on motor and functional recovery. Material and Methods: A retrospective cohort study was conducted in tertiary specialist centres in Singapore from 2010 to 2023. Adult patients diagnosed with ATCCS were included, while those with confounding neurological pathologies were excluded. ATCCSS, CCScore, and Subaxial AOSIS were calculated for all patients. The primary outcome was meaningful motor recovery at 12 months, defined as ≥ 20% improvement in the American Spinal Injury Association (ASIA) Motor Score (AMS). Secondary outcomes included improvement in Functional Independence Measure (FIM) and modified Japanese Orthopaedic Association (mJOA) scores. The models were tested using logistic regression and machine learning, specifically gradient boosting, with subgroup analysis for operative and non-operative management. Results: A total of 80 patients were included, with a mean age of 66.9 years (SD: 11.4). The majority (85.0%) were male, and 67.5% underwent surgical management. The median ATCCSS was 2 (IQR: 1), CCScore was 8 (IQR: 3), and Subaxial AOSIS was 8 (IQR: 6). The mean AMS at 12 months was 88.7 (SD: 17.4), with a mean improvement of 56.8% (SD: 72.3). ATCCSS had the highest predictive performance for AMS improvement at 12 months, with an area under the curve (AUC) of 0.588 (95% CI: 0.416 - 0.761), compared to CCScore (AUC: 0.355, 95% CI: 0.216 - 0.495) and Subaxial AOSIS (AUC: 0.401, 95% CI: 0.243 - 0.559). For mJOA improvement, ATCCSS again performed best with an AUC of 0.708 (95% CI: 0.556 - 0.861), followed by Subaxial AOSIS (AUC: 0.674, 95% CI: 0.505 - 0.844) and CCScore (AUC: 0.571, 95% CI: 0.393 - 0.749). However, for FIM improvement, CCScore outperformed the other scores with an AUC of 0.625 (95% CI: 0.440 - 0.810), followed by Subaxial AOSIS (AUC: 0.542, 95% CI: 0.358 - 0.727) and ATCCSS (AUC: 0.417, 95% CI: 0.241 - 0.592). In subgroup analysis, ATCCSS performed better in non-operative cases (AUC: 0.761, 95% CI: 0.483 - 1.039) compared to operative cases (AUC: 0.572, 95% CI: 0.372 - 0.771). The treatment concordance for ATCCSS was significantly higher in non-operative patients (96.2% vs 74.1%, p = 0.018), while CCScore showed the opposite trend (operative concordance 72.2% vs non-operative concordance 30.8%, p < 0.001). Conclusion: The ATCCSS score demonstrated superior predictive power for AMS and mJOA improvement compared to CCScore and Subaxial AOSIS, particularly in non-operative cases. However, CCScore was more effective for predicting functional recovery as measured by FIM improvement. Tailoring these scoring systems for local populations may further improve outcome prediction and clinical decision-making.

ID: 1372

A292: Impact of frailty and temporalis muscle thickness on outcomes in acute traumatic central cord syndrome: a retrospective analysis

Linda Lim Huiling ¹ , A Aravin Kumar ¹ , Zhiquan Damian Lee ¹ , Zhihong Chew ² , Andy Yeo Kuei Siong ² , Terry Teo Hong Lee ² , Dinesh Shree Kumar ² , Ji Min Ling ¹ , Lester Lee ¹

¹ National Neuroscience Institute, Department of Neurosurgery, Singapore, Singapore,

² Changi General Hospital, Department of Orthopaedic Surgery, Singapore, Singapore

Introduction: Frailty and sarcopenia are important predictors of outcomes in patients with acute traumatic central cord syndrome (ATCCS), particularly in older adults. Frailty, characterized by reduced physiological reserve, is associated with higher risks of complications and in-hospital mortality, while sarcopenia exacerbates recovery challenges. Temporalis muscle thickness (TMT) is an emerging indicator of sarcopenia and nutritional status, though its variability across age, gender, and ethnicity limits the establishment of standardized cutoffs. The interplay between frailty and sarcopenia may influence patient recovery and treatment strategies. This study aimed to assess the impact of frailty (using the Modified Frailty Index, MFI-5) and TMT on outcomes in both surgical and non-surgical patients with ATCCS. It explored correlations between frailty and TMT and evaluated changes in functional outcomes, particularly ASIA impairment scale scores, over 6 to 12 months. Materials and Methods: A retrospective study was conducted on patients diagnosed with CCS at tertiary specialist centres between 2015 and 2023. Patients were divided into surgical and conservative management groups. Frailty was measured using the MFI-5, based on the presence of diabetes, hypertension, congestive heart failure, chronic obstructive pulmonary disease (COPD), or pneumonia, along with functional independence. TMT was measured from axial computed tomography (CT) brain scans at the level of the Sylvian fissure, with the average of left and right values recorded. The outcomes evaluated included changes in American Spinal Injury Association (ASIA) Motor Score (AMS) scores, Functional Independence Measure (FIM) improvement, and Modified Japanese Orthopaedic Association (mJOA) scores at 6, and 12 months. Logistic regression was performed to assess the influence of MFI-5 and TMT on these outcomes, with results reported as means, standard deviations (SD), and p-values. Results: 80 patients were included in this study. The participants had a mean age of 65.4 years (SD = 12.1), and 62% (n = 58) underwent operative management. The mean AMS on arrival was 38.7 (SD = 12.5. The mean MFI-5 score in the cohort was 1.02 (SD = 0.8), while the average temporalis muscle thickness (TMT) measured 7.12 mm (SD = 1.45 mm). Frailty was significantly associated with poorer outcomes at 6 months, with a coefficient of -0.151 and p = 0.021. Frail patients had lower improvement rates (mean = 0.37, SD = 0.48) compared to non-frail patients (mean = 0.64, SD = 0.49). Similarly, FIM improvement was significantly reduced in frail patients (coefficient = -0.117, p=0.036,), indicating a negative impact of frailty on functional recovery. TMT was not found to significantly influence outcomes. TMT was not significantly associated with improvement of AMS at 6 months (p = 0.148) nor FIM improvement (p=0.183), indicating no significant effect of TMT on recovery. Neither frailty nor TMT predicted long-term outcomes at 12 months. Significant AMS improvement (p = 0.660) at 12 months and mJOA improvement (p = 0.932) showed no meaningful correlations with either variable. Conclusion: Frailty, defined as MFI-5, significantly affects short-term functional recovery, particularly at 6 months and in FIM improvement. However, long-term outcomes at 12 months are not significantly influenced by frailty or TMT, indicating that frailty’s impact may diminish over time.

ID: 511

A293: Traumatic cervical spinal cord injury: relationship of MRI findings to initial neurological impairment

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

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

Introduction: Traumatic cervical spinal cord injury (TCSCI) represents a significant health challenge in medicine. To date, several investigators have examined some objective parameters related to length, such as maximum spinal cord compression, for assessing cervical spinal cord compression, and demonstrated the relationship between the MRI measurements and the neurologic outcome. However, more detailed assessments of compression, using axial images and area calculations are still scant. To quantify the degree of available space for the cord and cord swelling in patients following TCSCI, and to assess the relationship among the available space for the cord, cord swelling, and the severity of neurologic impairment. Material and Methods: This study included 91 patients. Maximum cord available area (CAA_max) and maximum cord swelling area (CSA_max) were measured by two blinded observers. The American Spinal Injury Association Impairment Scale (AIS) grades were used to evaluate the extent of neurological injury. Relationship among CAA_max, CSA_max, and initial AIS grades were assessed via univariate and multivariate analyses. Results: Patients who were AIS grade A demonstrated significantly greater median CAA_max and CSA_max than AIS grade C or D (p < 0.01). Multivariate analysis identified only CAA_max (OR, 20.88 [95% CI, 1.50-291.21]; p = 0.024) and CSA_max (OR, 17.84 [95% CI, 1.15-276.56]; p = 0.039) were identified as independently influencing the likelihood of complete injury at the initial assessment. The classification accuracy were best for CAA_max and CSA_max; areas under the curve were 0.8998 (95% CI 0.7881-1.0000) and 0.9167 (95% CI 0.8293-1.0000), respectively. Conclusion: The present study provides a novel, objective, quantitative, and reliable radiologic method for identifying the severity of TCSCI with MRI findings. Greater available space for the cord (CAA_max > 38%) and cord swelling (CSA_max > 29%) can be used to identify patients at risk for TCSCI and both imaging characteristics are associated with an increased likelihood of severe neurological deficits (complete injury).

ID: 481

A294: Development and validation of a computed tomography imaging based artificial intelligence screening tool for acute cervical spine trauma

Husain Shakil ¹ , Zixuan Hu ² , Christopher Smith ³ , Armaan Malhotra ¹ , Ahmad Essa ³ , Hui Ming Lin ² , Zakariya M. Khan ² , Errol Colak ² , Christopher Witiw ^1,3

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

² St. Michael's Hospital, Unity Health Toronto, Department of Medical Imaging, Toronto, Canada,

³ St. Michael's Hospital, Unity Health Toronto, Division of Neurosurgery, Department of Surgery, Toronto, Canada

Introduction: Global estimates place the annual incidence of traumatic spinal injury at over 750,000 cases each year, contributing to substantial worldwide morbidity, and reduced quality of life among affected patients. In the setting of traumatic spinal cord injury (SCI), there is high quality evidence demonstrating earlier intervention leads to improved outcomes. This poses a significant health equity challenge to regional hospitals reliant on patient transfer for surgical treatment. In this study, we describe the development and testing of an artificial intelligence (AI) based automated screening tool to predict likelihood of surgical intervention for patients with a traumatic for traumatic injury to the cervical spinal column and/or spinal cord using computed tomography (CT) imaging obtained in the emergency department. Material and Methods: Patients with cervical spinal trauma treated at a level 1 adult trauma center in Ontario, Canada from 2005 to 2023 were retrospectively enrolled using a provincial trauma registry. Two channel separated convolutional networks (CSNs), three two-dimensional combination convolutional and recurrent neural networks (2D CNN-RNN), and two vision transformer (ViT) models were trained, internally validated, and tested using spine CT scans. Binary patient-level labels corresponding to whether the patient received surgical intervention to the spine served as the outcome of interest. Patients treated between 2005 and 2021 were assigned to a training-validation and internal test cohort, while those treated between 2022 and 2023 were assigned to a hold-out test set. Predictive errors were reviewed along with gradient weighted class activation mapping (Grad-CAM) images to explain model predictions. Results: There were 3,068 trauma patients with spine CT scans enrolled in the study with a mean age of 48.3 years (SD 19.6 years), and male predominance (N = 2155, 70%). There were 383 patients (12.5%) that underwent cervical spinal surgery for traumatic injury to the cervical spinal column and/or spinal cord. There were 2,254 patients in the training and validation cohort (N = 286 underwent surgery, 12.7%), 398 patients in the internal test cohort (N = 50 underwent surgery, 12.6%), and 416 patients in the hold-out test cohort (47 underwent surgery, 11.3%). The CSN models were found to have the greatest mean sensitivity (91.5%, 95% CI: 80.1 - 96.6%), specificity (94.0%, 95% CI 91.1 – 96.0%), area under the receiver operating characteristic curve (0.93, 95% CI: 0.89 - 0.97), negative predictive value (98.7%; 95% CI 96.7 - 99.5%), and positive predictive value (61.4%; 95% CI 48.4 - 72.9%). Grad-CAM evaluation revealed most false negatives were due to cases of isolated soft tissue injury, and false positives were structural injuries that were managed conservatively. Conclusion: This study demonstrates, for the first time, that AI-based prediction models can be used to identify patients with cervical spine trauma who are likely to require surgical intervention. The CSN architecture demonstrates good performance as a screening tool to assist in surgical triage of acute spinal injury and SCI. Further training of the model using an expanded multi-center data set will likely improve performance and generalizability.

ID: 2033

A295: Predictors of in-hospital mortality in patients with type II odontoid fractures: a retrospective single center study

Ziam Khan ¹ , Matthew Kreinbrink ¹ , Emmeline Leggett ¹ , Kevin Kim ² , Timothy Chryssikos ²

¹ University of Maryland School of Medicine, Baltimore, United States,

² University of Maryland School of Medicine, Department of Neurosurgery, Baltimore, United States

Introduction: Type II odontoid fractures are common spine injuries which may present in isolation or in the setting of multi-trauma. This study sought to identify independent predictors of in-hospital mortality in patients with new diagnosis of Type II odontoid fracture. Material and Methods: This retrospective study assessed 237 patients admitted with new diagnosis Type II odontoid fracture to a Level 1 Trauma Center between January 2016 to March 2024. Demographic, clinical, radiographic, and surgical data were collected. Summary statistics were performed. Univariate analysis was performed for head-to-head comparison of patients by in-hospital mortality status. Significant variables after checking for collinearity were included in a multivariable model using stepwise backward selection. Results: Mean age was 75.5 ± 6.4 years, and 54% of patients were male. Fall was the most common injury mechanism (81.7%), followed by motor vehicle collision (12.3%), assault (3.4%), and pedestrian incidents (2.6%). Multiple traumatic injuries were present in 22.33%. Mean Injury Severity Score (ISS) was 12.77 ± 7.1, and mean GCS was 13.95 ± 2.75. Twenty-four patients (10.1%) had traumatic brain injury (TBI) and 14 patients (5.9%) had spinal cord injury (SCI). Overall mortality was 9.7%. In patients with TBI and SCI, mortality was 19% and 50%, respectively. We observed a bimodal distribution of mortality by age, with peaks at 25-35 years and 65-95 years. Head-to-head comparison of patients stratified by in-hospital mortality revealed that patients who expired were significantly older (p = 0.034), presented with lower systolic blood pressure (p < 0.001), diastolic blood pressure (p < 0.001), respiratory rate (p < 0.001), GCS (p < 0.001), Trauma Injury Severity Score (TRISS) (p < 0.001), Revised Trauma Score (RTS) measured at both the scene (p = 0.03) and upon admission (p < 0.001). Patients who expired had higher admission heart rate (p = 0.010), ISS (p = 0.006), rates of SCI (p < 0.001), and surgical intervention (p = 0.005). Multivariable analysis demonstrated that older age, ISS, heart rate, and presence of SCI were independent and significant predictors of in-hospital mortality. Conclusion: There was a bi-modal age distribution of in-hospital mortality among patients admitted with new diagnosis of Type II odontoid fracture. Higher ISS and presence of SCI but not TBI independently predicted in-hospital mortality. Higher admission heart rate also independently predicted in-hospital mortality. Except for age, demographic variables including 5-item Frailty Index, Area Deprivation Index, and smoking status did not predict in-hospital mortality.

ID: 916

A296: Type 2 odontoid fractures: atlantodental arthritis as a novel risk factor for failure of conservative management

Taylor Paziuk ¹ , Pratheek Makineni ¹ , Ashley Zheng ¹ , Belding Jonathan ¹ , Michael Kelly ¹ , Timothy Moore ¹

¹ MetroHealth, Cleveland, United States

Introduction: No current consensus exists regarding the optimal management of type 2 odontoid fractures in the elderly as the potential morbidity associated with both operative and nonoperative treatment is significant. Therefore, it is imperative that treating providers identify all variables associated with improved outcomes with either treatment modality to optimize patient outcomes and avoid failures of either index treatment modality. Radiologic atlantodental arthrosis is one such variable that may impact fracture healing given the fact that a more rigid lever arm adjacent to a fracture site induces greater biomechanical strain on what is an already tenuous fracture healing environment. Therefore, the purpose of this study is to assess how both the presence and grade of atlantodental arthrosis relate to outcomes of non-operatively managed Type 2 odontoid fractures. Methods: Patients presenting to an emergency room of a single level-1 trauma center with a Type 2 odontoid fracture treated between 2017-2023 were retrospectively identified using ICD-10 codes. Patients with an infectious, oncologic, or iatrogenic etiology of fracture were excluded along with individuals who received initial surgical treatment. Demographic and comorbidity information was collected. Radiologic evaluation was conducted on index CT and initial upright x-rays of the cervical spine for initial fracture angulation and displacement. Atlantodental arthrosis severity on index CT was scored based on the classification system established by Liu et al., which qualitatively graded the degree of arthrosis as 1 for mild, 2 for moderate, 3 for severe, and 4 for fused, based on osteophyte formation and imposition on the atlantodental and dental-basion intervals1. Failure of conservative treatment was defined by surgical stabilization within 6 months of injury due to functionally limiting pain in the setting of concordant fracture nonunion and mobility. Multivariable regression and Pearson correlation were utilized to assess the relationship between atlantodental arthrosis and failure of conservative management. Results: 81 patients were included in the study, with an average length of radiographic follow up from the date of injury of 180 days. There was no difference in demographics between the conservative treatment failure and success groups (p > 0.05). Patients who failed conservative treatment were more likely to have an atlantodental osteoarthritis (OA) grade > 2 (p < 0.001) and increased posterior displacement on index imaging (p = 0.008). Following multivariable regression, OA grade 3 (OR 4.4, 95% CI: 1.6 to 11.9, p = 0.004) and grade 4 (OR 13.9, 95% CI: 1.5 to 127.9, p = 0.02) were independently associated with increased risk for failing conservative management. Additionally, increased OA grade was correlated with failure of conservative management (r = 0.519, p < 0.001). Conclusion: This study represents the first of its kind to identify atlantodental arthrosis as a risk factor for failure of conservatively managed type 2 odontoid fractures. Further prospective studies are necessary to evaluate this metric as a possible data point in determining treatment modality of patients with type 2 odontoid fractures.

ID: 2644

A297: The association of insurance status with outcomes and procedural administration in cervical spine trauma

Sanket Mehta ¹ , Nicholas Danford ²

¹ Stanford University, Department of Orthopaedic Surgery, Palo Alto, United States,

² Columbia University Medical Center, Department of Orthopaedic Surgery, New York, United States

Introduction: Uninsured patients experience greater delays in care, undergo fewer procedures, and have higher postoperative complication rates when compared to insured patients. However, the relationship between insurance status and disparities in care for patients sustaining cervical spinal trauma is poorly understood. This study investigates the association of lack of insurance with clinical outcomes and the probability of diagnostic and therapeutic procedure administration to patients undergoing cervical spine trauma in Levels I-IV trauma centers. Materials and Methods: We performed a retrospective cohort study involving cervical spine trauma patients aged 18 to 64 years registered in the National Trauma Data Bank (NTDB) 2011-2019. Patients who were missing race information, dead on arrival, or had an injury severity score (ISS) less than 9 were excluded. Baseline patient characteristics were compared using bivariate analysis. Multivariate logistic analysis was employed to investigate the association of nonwhite race with in-hospital mortality, complications, and select diagnostic and therapeutic procedure administration, adjusting for age, sex, insurance status, ethnicity, ISS, presence of shock, mechanism of injury, intent of injury, Glasgow Coma Scale motor score, significantly different comorbidities, and year of admission. Results: A total of 118,306 patients with acute cervical spine trauma met the inclusion criteria. Overall, 98,495 patients (83.3%) were insured and 19,811 patients (16.7%) were uninsured. Uninsured patients had a higher rate of alcoholism and current smoking status and a lower rate of bleeding disorder, congestive heart failure, chronic renal failure, diabetes mellitus, functionally dependent health status, history of myocardial infarction, hypertension, respiratory disease, and cirrhosis. Uninsured patients were younger (37 vs. 43 years) and more likely to present in shock (7.0% vs. 5.4%; p < 0.001 for all). In-hospital mortality rate was greater in uninsured patients compared to their insured counterparts (10.2% vs. 6.4%; p < 0.001). Multivariable logistic regression analyses demonstrated an association of uninsured status with increased likelihood of in-hospital mortality (odds ratio [OR] = 1.79, p < 0.001) and cardiac arrest (OR = 1.19, p = 0.002). Despite this, uninsured status was associated with decreased likelihood of any complication (OR = 0.81; p < 0.001), acute respiratory distress syndrome (OR = 0.78; p < 0.001), urinary tract infection (OR = 0.74; p < 0.001), deep vein thromboses (OR = 0.68; p < 0.001), pulmonary embolism (OR = 0.69; p < 0.001), severe sepsis (OR = 0.74; p = 0.001), stroke (OR = 0.77; p = 0.01), unplanned intensive care unit admission (OR = 0.87; p = 0.02), unplanned intubation (OR = 0.77; p < 0.001), and unplanned return to operating room (OR = 0.79; p = 0.005). In a multivariable analysis of select diagnostic and therapeutic procedure administration, uninsured status was associated with an increased likelihood of receiving computerized tomography (CT) of the spine (OR = 1.05; p = 0.005) and decreased likelihood of receiving magnetic resonance imaging (MRI) of the spine (OR = 0.88; p < 0.001) and operative spinal fixation (OR = 0.79; p < 0.001). Uninsured patients also had an increased likelihood of being withdrawn from care (OR = 1.23; p < 0.001). Conclusion: In summary, uninsured status was independently associated with increased in-hospital mortality and withdrawal of care, as well as decreased rates of resource-intensive diagnostic and therapeutic procedures administration. Despite controlling for many of the medical factors that can influence outcomes, our data indicate that disparities in diagnostic and therapeutic workup in the acute post-trauma setting may contribute to insurance-based disparities in cervical spine trauma outcomes.

OP34: Adolescent Spinal Deformity 2

ID: 2726

A298: A retrospective analysis of skeletally maturing and mature MT and TL/L AIS Curves (40-66 deg) treated by mini-open anterior scoliosis correction using dual screw-line technique and multi-level thoracic and lumbar intervertebral de-tethering

Darryl Antonacci ¹ , Yashvi Verma ¹ , Caitlin Antonacci ¹ , Sam Dechario ¹ , Janet Cerrone ¹ , Madeline Sweeney ¹ , Laury Cuddihy ¹ , Christopher Antonacci ¹ , Randal Betz ¹

¹ Institute For Spine & Scoliosis, Lawrenceville, United States

Introduction: Anterior scoliosis correction with anterior longitudinal ligament and annular disc complex intervertebral detethering (ASC with ALL-ADC release) is a multi-year, multi-generational advancement upon vertebral body tethering, and is predominately a dual screw-line, multi-level thoracic and/or lumbar intervertebral “de-tethering” procedure with additionally one to two levels of bilaterally released and instrumented transition zones in double curves. Unlike vertebral body tethering alone, as published previously, the technique allows for significant de-rotation, curve correction, preservation of segmental vessels, and restoration of sagittal balance by addressing the underlying ligamentous and disc contractures of the scoliotic spine. It has been used to treat from EOS to adolescents with minimal or no growth remaining, and adults. In this retrospective IRB-approved analysis, we report outcomes of a cohort of skeletally maturing or mature patients. Material and Methods: 249 consecutive patients who underwent anterior scoliosis corrections for AIS by single surgeon, DA, at our institution from June 2020 to August 2022 were considered. Only skeletally maturing or mature patients (Sanders ≥ 3b) with operative MT and/or TL/L curves (between 40-66°, T5-L4), and who underwent mini-open anterior scoliosis corrections using predominately dual screw-line cord instrumentation with multi-level ALL-ADC intervertebral de-tethering release were included (n = 132). Of 132 qualifying patients, 96 patients (73%) with 130 treated curves (81 MT, 49 TL/L) had mean radiographic 30.2 months FU (range: 22 to 49 mo.). Cobb angles measured, AP: PT, MT, TL/L, L-Pelvic angle; and Lateral: C2-C7, T5-T12, L5-S1, for PreOp, Post-Op First Standing, and Post-Op latest FU, as well as Preop bends MT and TL/L. Results: Mean age at surgery was 17.5 y (range: 10 to 46) and Sanders, 6.7 (range: 3.5-8). PREOP: mean MT cobb was 52.2° (40-66°); mean TL/L cobb was 52.4° (37.1-68.6°); and mean 3D kyphosis T5-T12 was 2.3° (range -13.4 to 36.5). POST-OP 2 yr: Mean MT instrumented cobb was 11.2° (0.2-29.8°), Mean MT max 14.6°, (p < .0001, range: .2-33.7°); 72% correction. Mean TL/L instrumented cobb was 7.7° (0.1-21.3°), Mean TL/L max 8.8°, (p < .0001, range: 0.1-25.6°); 83% correction; and mean 3D kyphosis was 41.7° (12.9 to 56.2°). MT instrumented curves had mean 5.5 (range: 4-8) levels ALL-ADC intervertebral detethering releases; TL/L curves had mean 3.7 (range: 1-8) levels of ALL-ADC detethering releases. Peri-operative transfusion rate was 3/96 pts (3%). No infections. No significant IONM MEP changes during correction maneuvers. No revisions for loss of curve correction. 1 patient had partial removal of symptomatic instrumentation > 1y after surgery without significant loss of correction. 2 yr mean Oswestry low back pain score was 3.7 ± 4.8 (no disability) with 59.3% responding by abstract submission. Conclusion: The 2-4 yr results of ASC with multi-level ALL-ADC intervertebral detethering of 40-66° AIS is consistent with previously published data, and demonstrates mean corrections of 72%, and 83% in MT and TL/L max curves. Clinical success (max cobb ≤ 30°) was 95/96 (98%) of patients. Preliminary collection of functional pain scores and clinical follow-up does not suggest detrimental effects of ALL-ADC releases at mean 30.2 months follow-up.

ID: 2941

A299: Adolescent vs. young adult idiopathic scoliosis patients: should an older teen wait until adulthood to have a spinal fusion?

Alexandra Dionne ¹ Fthimnir Hassan ¹ , Chidebelum Nnake ¹ , Simon Blanchard ¹ , Justin Reyes ¹ , Roy Miller ¹ , Joseph Lombardi ¹ , Zeeshan Sardar ¹ , Lawrence Lenke ¹

¹ Columbia University Medical Center/NewYork-Presbyterian Och Spine Hospital , New York, United States

Introduction: The timing of corrective surgery is a critical question for surgeons treating patients with idiopathic scoliosis (IS). There is limited evidence to suggest that patients with IS who are operated on as adolescents (AIS) have better postoperative alignment and fewer surgical complications than those operated on as young adults (YAdIS). Thus, we sought to determine whether AIS patients have better long-term postoperative outcomes, complication rates and radiographic alignment than YAdIS patients. Material and Methods: This was a single center, retrospective comparative study of 237 patients with AIS (age 10-18, n= 145) or YAdIS (age 19-40, n=92) idiopathic scoliosis patients all of which had elective primary corrective surgery. Patients were included if they had a minimum follow up of 2 years. To minimize potential bias, a 1:1 propensity score matching (PSM) analysis was done matching on curve type, gender, main coronal cobb angle, and instrumented levels. Intraoperative outcomes, perioperative and long-term complications, coronal and sagittal radiographic alignment correction, and patient-reported outcomes (PROs) including the Oswestry Disability Index (ODI) and Scoliosis Research Society (SRS)-22r survey were compared between the two groups. Results: The 1:1 PSM of the generated two groups of 27 patients with identical gender ratios and curve types. The AIS group had lower preoperative Hb/Hct than YAdIS (11.8[1.9] vs 13.2[1.2] and 35.2[5.5] vs 39.4[3.3], p = 0.0213 and 0.0147 respectively) and lower age and BMI (p < 0.05), which was expected. Preoperative radiographic parameters were equal, except that AIS patients had slightly less lordosis (55.6^o[14.0] vs 61.8^o[11.7], p = 0.0486). AIS had lower OR time (4.7[1.2] hrs vs 5.2 [1.5] hrs, p = 0.0468), intraoperative transfusion rates (70.4% vs 96.3%, p = 0.0082), and postop Hb/Hct (9.0[1.9] vs 10.1[1.4] and 26.4[5.4] vs 29.7[3.7], p = 0.0280 and 0.0453 respectively). Other intraoperative outcomes and complications were the same (EBL, transfused pRBC and cell saver, surgical site infection, dural tears, and nerve root weakness, p > 0.05). Postoperatively, AIS patients had a lower rate of hypotension (7.4% vs 25.9%, p = 0.0253) and less pRBCs transfused (1.0[0.0]u vs 1.6[0.8]u, p = 0.0400). They also had smaller T2-T12 TK (36.3^o[11.0] vs 42.7^o[13.6], p = 0.0412), T2-T5 TK (13.3^o[8.7] vs 19.4^o[9.4], p = 0.0187), and T1PA (7.4^o[8.9] vs 12.4^o[7.9], p = 0.0200). The magnitude of correction of all spinal parameters was equal except for T1PA (1.0^o[5.1] vs 5.3^o[5.0], p = 0.0060) and CVA (-0.9[2.0] cm vs 0.6[2.1] cm, p = 0.0085), indicating that AIS had greater coronal correction to the left while YAdIS had greater correction to the right. Long-term rates of complications, revisions and mechanical failures, as well as baseline and follow-up PROs, were equivalent (p > 0.05). Conclusion: AIS patients have lower OR time, intraoperative transfusion rate, and postoperative transfused pRBCs and hypotension. Otherwise, they have comparable perioperative and long-term complication and revision rates and PROs to YAdIS patients. Radiographically, they have smaller postoperative T2-T12 TK, T2-T5 TK and T1PA, with greater CVA correction to the left versus the right.

ID: 2733

A300: Validation of an automatic tool for adolescent idiopathic scoliosis screening using a smartphone application based on surface tomography

Thierry Odent ¹ , Paul Martrenchar ²

¹ CHRU Tours, Orthopedic Pediatric Surgery, Tours, France,

² CHRU Tours, Orthopedic Surgery, Tours, France

Introduction: Adolescent Idiopathic Scoliosis (AIS) is a spinal deformity affecting 0.47-5.2% of the population. Current AIS screening and management face challenges, including late detection and insufficient follow-up, often resulting in surgical interventions when conservative treatment is outdated. This study evaluates a smartphone application (SA) based on surface topography for the early detection of scoliosis and estimation of the Cobb angle. Patient and Methods: A multi-center prospective study was conducted involving 170 pediatric patients from two reference hospitals in France and Canada. The participants included both scoliotic patients and healthy controls, all aged 8-18 years. Mean age of the patients was 14 years (9-21) and 84% were female. The SA was used to capture video scans of the patients, which were then analyzed using AI to estimate the Cobb angle. The results were compared to standard radiographic measurements (EOS antero-posterior and lateral spine X-rays) to validate the accuracy of the SA. Results: The study found that the SA had a mean average error (MAE) of 6.2° when estimating Cobb angles, with a high correlation (90%) compared to radiographs. The SA demonstrated a sensitivity (Se) of 91% and specificity (Sp) of 77% for detecting scoliosis at a Cobb angle of ≥ 10°, and even higher accuracy (97% (Se) and 92% (Sp)) for more severe angles such as an angle ≥ 20° (which is the reference threshold for conservative treatment). The application also showed potential for reducing the need for X-rays by providing a reliable, non-radiographic method for scoliosis screening. Conclusion: The SA is presented as a promising tool for AIS screening and diagnosis, particularly in school settings, where early detection is crucial. By integrating this technology, the proportion of conservative treatments could increase, reducing the need for surgical interventions and minimizing X-ray exposure. The SA shows significant potential for improving AIS screening and management. Future studies will focus on using the SA to monitor disease progression.

Keywords: Adolescent idiopathic scoliosis, scoliosis screening, body surface topography, artificial intelligence

ID: 2839

A301: VerteRo: a deep neural network approach for estimating vertebral body rotation in adolescent idiopathic scoliosis

Sompoom Sunpaweravong ¹ , Sittisak Honsawek ² , Rajalida Lipikorn ³ , Vit Kotheeranurak ^4,5

¹ Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand,

² Department of Biochemistry, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand,

³ Department of Mathematics and Computer Science, Faculty of Science, Chulalongkorn University, Bangkok, Thailand,

⁴ Department of Orthopaedics, Faculty of Medicine, King Chulalongkorn Memorial Hospital, Chulalongkorn University, Bangkok, Thailand., Bangkok, Thailand,

⁵ Center of Excellence in Biomechanics and Innovative Spine Surgery, Chulalongkorn University, Bangkok, Thailand, Bangkok, Thailand

Introduction: The axial vertebral body rotation (VBR) angle is an important measurement for planning the placement of pedicle screws during spinal fusion surgeries along with prognosis monitoring for patients with Adolescent Idiopathic Scoliosis (AIS). Recently, the most widely accepted methods for measuring axial VBR angle such as the Ho et al method utilizes Magnetic Resonance Imaging (MRI) or computed tomography (CT) scans, both of which have significantly lower availability and higher costs than anteroposterior (AP) view spine radiographs [1,2]. Using AP view spine radiographs can also reduce the radiation dose by 555 times when compared with spine CT scans along with preventing triggers of claustrophobia and significantly reducing the scanning time for each patient [3]. This study aims to construct a deep neural network (DNN) algorithm capable of estimating the axial Vertebral Body from anteroposterior (AP) view radiographs with greater accuracy than the current visual methods of estimating axial VBR angles such as the Nash-Moe method. Material and Methods: Model training and testing was conducted utilizing a feedforward deep neural network regression model. In the preliminary phase of our study (up to September 2024), 204 samples from all levels of the thoracolumbar spine were split into 3 pools, 164 samples (80.4%) were used for training, 20 were used for validation (9.8%) and 20 were used for testing (9.8%). Samples were labelled with the axial VBR angles measured from MRI scans using the Ho et al method [1]. Results: The VerteRo deep neural network algorithm estimated axial VBR angles with a mean squared error (MSE) of 1.5016 when tested on the testing sample which was isolated from the training and validation datasets in accordance with established frameworks for ethical research of artificial intelligence (AI) applications in medicine [4]. Conclusion: The VerteRo algorithm can estimate axial VBR angles with accuracy comparable to or greater than currently existing radiographic methods for estimating axial VBR angles such as the Nash-Moe method. The authors will continue training and testing on VerteRo with at least 1,700 more thoracolumbar samples before the oral presentation at GSC 2025.

References

1. Lam GC, Hill DL, Le LH, Raso JV, Lou EH. Vertebral rotation measurement: a summary and comparison of common radiographic and CT methods. Scoliosis. 2008 Nov 2;3:16. https://doi.org/10.1186/1748-7161-3-16

2. Taylor, John & Bussières, André. (2012). Diagnostic imaging for spinal disorders in the elderly: a narrative review. Chiropractic & manual therapies. 20. 16. https://doi.org/10.1186/2045-709X-20-16

3. Richards PJ, George J, Metelko M, Brown M. Spine computed tomography doses and cancer induction. Spine (Phila Pa 1976). 2010 Feb 15;35(4):430-3. https://doi.org/10.1097/BRS.0b013e3181cdde47

4. Crossnohere NL, Elsaid M, Paskett J, Bose-Brill S, Bridges JFP. Guidelines for Artificial Intelligence in Medicine: Literature Review and Content Analysis of Frameworks. J Med Internet Res. 2022 Aug 25;24(8):e36823. https://doi.org/10.2196/36823

Funding: This research project is supported by the Quick Win project of the Ratchadapiseksompoctch Fund, Chulalongkorn University which granted 25,691.15 USD (853,100 THB) to support this project.

Keywords: Artificial Intelligence, Adolescent Idiopathic Scoliosis, Spinal Fusion, Image Processing, Preoperative Planning

ID: 2443

A302: A predictive model for immediate postoperative X-rays of adolescent idiopathic scoliosis following posterior spinal fusion surgery based on generative neural networks: SVV-Net

Nan Wu ¹ , Jianguo Zhang ¹ , Yuanpeng Zhu ¹ , Xiangjie Yin ¹ , Xueyi Zhang ¹ , Di Liu ¹ , Guilin Chen ¹ , Qing Li ¹

¹ Peking Union Medical College Hosptial, Beijing, China

Introduction: Accurately predicting the surgical outcomes of posterior spinal fusion (PSF) in adolescent idiopathic scoliosis (AIS) patients is crucial, as it significantly assists surgeons in making well-informed decisions. Generative neural networks, such as GANs and VAEs, not only enhance medical diagnostics and accelerate drug discovery but also support personalized medicine by generating realistic synthetic data and effectively modeling disease progression. Material and Methods: We retrospectively included patients who underwent PSF surgery at a single center for training and test cohorts, while prospectively enrolling AIS patients scheduled for surgery. We developed the SVV-Net (Scoliosis-VQ-VAE) model, which includes an Encoder, Codebook, Decoder, and Transformer to integrate pre-operative X-ray features with surgical data for post-operative images. Model effectiveness was evaluated through image quality analysis, postoperative parameter assessment, and clinical review, using six metrics to compare generated and real X-rays. CCC measured agreement between generated and real Cobb angles. Two orthopedic surgeons rated the generated X-rays on clarity, authenticity, accuracy, reasonableness, and usability on a scale of 0 to 10. Results: A total of 720 patients met the inclusion criteria and were randomly divided into training (n = 540, mean age 14.4 ± 1.7 years, 87.8% female) and test cohorts (n = 180, mean age 14.4 ± 1.7 years, 85.0% female), with an additional 79 patients (mean age 14.5 ± 1.6 years, 89.9% female) in the prospective cohort. SVV-Net outperformed other generative models across six image quality metrics. The Cobb angles from generated images showed strong consistency with real images (CCC: 0.90 [internal] and 0.91 [prospective]), while the Cobb angle improvements also demonstrated high consistency (CCC: 0.97 [internal] and 0.96 [prospective]). Differences in UIVs and LIVs were minimal in both cohorts. Evaluator 1 rated clarity and authenticity highest (7.61 and 7.54), while Evaluator 2 gave the highest scores for usability and reasonableness (7.58 and 7.57). The average total score was 37.3 (± 5.3). Conclusion: We developed a model to predict immediate postoperative X-rays from preoperative X-rays of AIS patients and confirmed its effectiveness. The results of our model have demonstrated reliability through multiple validation methods, indicating that this model could assist clinicians in practice.

ID: 364

A303: Dystrophinopathy in paravertebral muscle of adolescent idiopathic scoliosis: a prospective cohort study

Junyu Li ¹ , Danfeng Zheng ¹ , Zekun Li ¹ , Jiaxi Li ¹ , Zexi Yang ¹ , Xiang Zhang ¹ , Y Zhang ¹ , Miao Yu ¹

¹ Peking University Third Hospital of China, Beijing, China

Introduction: Adolescent Idiopathic Scoliosis (AIS) is commonly associated with muscle pathology based on previous studies, but the patients did not show typical symptoms of decreased limb muscle strength and respiratory muscle function limitation. So AIS may be a particular kind of core myopathy, and we infer that the pathological changes of paravertebral muscles are involved in the development and evolution of AIS, especially the proteins therein. Based on the hypothesis that the onset and clinical progression of AIS may be associated with certain neuromuscular diseases, we used pathological methods to further analyze paraspinal muscle changes in AIS patients and introduced immunohistochemical antibody markers used in neuromuscular disease diagnosis through routine morphology. And we are particularly interested in the Dystrophin protein which is the pathogenic factors of Duchenne muscular dystrophy. Material and Methods: A total of 40 AIS patients were included in the case series, all of whom received posterior scoliosis correction surgery. Neurological, muscular, neuromuscular, and rheumatologic illnesses, malignancies, surgical correction history, and exercise therapy treatment were excluded. None of the patients in this series underwent preoperative physiotherapy or wore braces. The patients were also separated into mild (Nash-Moe 0 and I) and severe (Nash-Moe II and III) Nash-Moe groups to determine if dystrophin protein deficiency increased with vertebral rotation. Controls were 20 Congenital Scoliosis (CS) and 20 Spinal Degenerative Disease (SDD) patients. The biopsy of the muscle should be slightly away from the tendon tissue to avoid non-specific pathological morphology. The biopsy tissue was wrapped in a semi-humid saline gauze and immediately transferred to the laboratory, where it was drained with blotting paper and was consecutively embedded in tragacanth and OCT compound (Tissue-Tek) and finally frozen in isopentane pre-cooled in liquid nitrogen. This process avoids autolytic or irreversible artificial artifacts in muscle tissue within half an hour. Cryostat slices were 7-10μm thick. Conventional H&E staining, histochemical staining (NADH-TR), and EnVision two-step immunohistochemical staining were performed under standard techniques that used the following primary antibodies: Dystrophin-1 (Anti-dystrophin rod domain), Dystrophin-2 (Anti-dystrophin C-terminal), Dystrophin-3 (Anti-dystrophin N-terminal), Myosin. Results: There were significant deletions of dystrophin-1 (p < 0.001), dystrophin-2 (p < 0.001) and dystrophin-3 (p < 0.001) in AIS group compared with both CS group and SDD group. The higher the Nash-Moe classification in the AIS group, the more significant the loss of dystrophin-2 (p = 0.042) in the convex paraspinal muscles. In addition, there was a negative correlation between the dystrophin-1 and 2 on the concave side of AIS group and Cobb Angle, and there was a significant correlation between dystrophin-2 and Cobb Angle (p = 0.011). Conclusion: Dystrophin protein deficiency in the paraspinal muscles plays a significant role in the formation and progression of AIS. The severity of scoliosis in AIS patients is correlated with the extent of dystrophin loss in the paravertebral muscles. Therefore, dystrophin dysfunction may be relevant to the occurrence and development of AIS.

ID: 69

A304: Deformity correction at the disc angle level with limited apical fusion of structural disc levels and fusionless treatment of non-structural disc levels results in fewer levels fused and preserved lumbar spine range of motion in Lenke 5 and 6 AIS

Saechin Kim ¹

¹ Mass General Brighaml/Harvard Medical School, Orthopaedic Surgery, Boston, United States

Introduction: Adolescent idiopathic scoliosis (AIS) Lenke 5 and 6 curves present a challenge in preserving lumbar spine (LS) range of motion (ROM) in pediatric scoliosis surgery (PSS). The standard posterior PSS has been a spinal fusion (SF) that spans above and below the major structural curve that includes non-structural disc levels (nSDLs) that can correct significantly with side bending (SB). Though not including the nSDLs in the SF may preserve ROM, more limited SF has been associated with increased rates of adding on phenomenon (AO) and revision surgery (RS). We describe a novel method using intravertebral interpedicle (IVIP) constructs made of commercially available connectors and iliac lateral extenders (ILE) placed transversely into the pedicle screw tulips of the same vertebra that limits SF to the apex of the structural curve by correcting the angular deformity at each individual disc level as can be done in anterior SF for deformity and the nSDL deformity without fusion to reduce the risk for AO and RS. Our hypothesis is that the IVIP method is safe, results in fewer levels fused, and preserves LS ROM. Material and Methods: IVIP constructs with open ILE placed are used for SF and closed ILE with polyethylene terephthalate sublaminar bands placed through the closed heads are used for fusionless posterolateral vertebral tethering (PLVT). After IRB approval of this prospective study, we compared the results using the IVIP method to that of matched historical standard posterior fusion controls (MHFC). Inclusion criteria were Lenke 5 and 6 AIS with minimum 24 month f/u. Radiographic measurements from x-rays at 3-month and final f/u assess for AO and from bending x-rays at pre-op and at f/u determine the ROM as the difference between the right and left side bending (SB) lumbar T12L5 Cobb angles (SBROM) and between flexion and extension L1S1 Cobb angles (FEROM). SRS 22r Questionnaire was scored pre-op and at each f/u. Results: In the IVIP group (n = 7), avg age was 16.0 ± 2.2 years (Risser stages 3 (n = 1), 4 (n = 3) and 5 (n = 3)). The main curve (pre-op 57^o ± 8^o) had avg correction of 82% (post-op 10^o ± 8^o). The avg number of levels fused (4.0 ± 1.3) in the IVIP group was less than that in the MHFC (10.1 ± 1.5) (p < .0001) and the lowest fused level is L1 or L2 in the IVIP group and L3 or below in the MHFC. At avg of 31-month f/u (min. 24m), no PLVT failure, AO, or RS was seen. Avg SBROM at pre-op (25^o ± 11^o) and at f/u (28^o ± 14^o) were not statistically different (p = .45). Avg post-op FEROM was 41^o ± 13^o, within the normal range discussed in the literature. Avg SRS-22r score at final f/u was 4.5/5 and pre-op was 4.0/5 (p < .01). Conclusion: The IVIP method of apical SF and fusionless PLTB of nSDLs can result in fewer levels fused, be used for patients in wide range of age groups, is safe, and preserves LS ROM. We hope that the IVIP method can promote a paradigm shift from global correction of spinal deformity to correction at each disc level in PSS.

ID: 493

A305: Feasibility of modified halo-pelvic distraction technique in the management of severe spinal deformities in low-and middle-income countries: a pilot study in East Africa

Romani Roman Sabas ¹ , Magalie Cadieux ² , Bryson Mcharo ¹ , Albert Isaacs ³ , Muhammad Saad Ilyas ⁴ , Juma Magogo ¹ , Alexander Schupper ⁵ , Massimo Balsano ⁶ , Salim Msuya ¹ , Honest Massawe ⁷ , Hamisi Shabani ¹ , Amer Aziz ⁴ , Roger Härtl ⁸ , Alaa Azmi Ahmad ⁹

¹ Muhimbili Orthopaedic Institute, Division of Neurosurgery, Dar Es Salaam, Tanzania,

² Washington University in St. Louis, USA, Department of Neurosurgery, St. Louis, United States,

³ Nationwide Children’s Hospital, Columbus, Ohio. USA, Department of Neurosurgery, Ohio, United States,

⁴ Ghurki Trust Teaching Hospital,, Division of Orthopaedics and Spine Surgery, Lahore, Pakistan,

⁵ Icahn School of Medicine at Mount Sinai, New York, USA, Department of Neurological Surgery, New York, United States,

⁶ University and Hospital Trust, AOUI, Verona, Italy, Regional Spinal Department, Verona, Italy,

⁷ Kilimanjaro Christian Medical Centre, Moshi, Tanzania, Department of Orthopaedics, Moshi, Tanzania,

⁸ Weill-Cornell Medicine Och Brain & Spine, Department of Neurosurgery, New York, United States,

⁹ Palestine Polytechnic University, Paediatric Orthopaedic Surgery, Ramallah, Palestine

Introduction: Pediatric scoliosis, defined by a Cobb angle of at least ten degrees, affects 2-3% of children globally. Pediatric spine deformity, often arising from congenital or neuromuscular causes, can significantly impair cardiopulmonary and intra-abdominal function. Early identification and timely management are crucial to slowing curve progression. However, patient presentation varies by region: in resource-rich settings, scoliosis is often detected early, allowing for conservative management, whereas in low-to-middle-income countries (LMICs), patients frequently present late with severe curvatures exceeding 90 °. These advanced cases not only preclude non-surgical management but also increase the risks associated with surgical intervention. For severe curves, preoperative reduction is essential to mitigate surgical risks. The halo pelvic Ilizarov distraction device, a recently modified preoperative technique, aims to reduce severe spinal curvature and improve surgical outcomes. This study evaluates the feasibility of this modified device in an LMIC setting, focusing on its effects on curve correction, neurological function, and complication rates. Material and Methods: A prospective study was conducted at the Muhimbili Orthopedic Institute (MOI) in Dar es Salaam, Tanzania, from June 2023 to July 2024. A global surgery workshop on placing a newly modified halo-pelvic Ilizarov traction device was held at MOI, involving eight local surgeons in collaboration with the Ghurki group, who developed the device. Seven patients with severe scoliosis were enrolled, each undergoing treatment with the modified halo-pelvic distraction device over a 13-week period. Radiographic changes in Cobb angle, neurological function, and complication rates were assessed at defined treatment intervals. Statistical analyses were performed using Friedman and Wilcoxon signed-rank tests to evaluate the significance of observed trends. Results: The cohort comprised seven patients with median age of 15 years (14-20) and median Cobb angle of 110.0° (92.0°-120. 0°). The majority were male 57.1% (4/7), with AIS being the most common diagnosis (42.8%, 3/7). The application of the modified halo-pelvic distraction device resulted in a reduction in the median Cobb angle from 110.0° pre-traction to 76.0° post-traction (30.8% correction), and further to 69.0° after 13 weeks (37.1% correction) (p = 0.027). Complications were observed in two patients (28.6%): one developed Superior Mesenteric Artery (SMA) syndrome, managed by reducing traction forces, and another experienced lower limb weakness (MRC 2/5. Traction forces were adjusted, and the halo was removed three weeks later. The patient showed progressive improvement, with muscle strength increasing to (MRC 4/5) after six months follow up. No cases of cranial nerve paralysis or severe pin site infections were reported. Six patients (85.7%) underwent definitive surgery after halo traction, resulting in a final median Cobb angle of 49° (32.0°-55.2°). Conclusion: The modified halo-pelvic Ilizarov traction device presents a promising option for the staged management of severe, neglected pediatric spinal deformities commonly encountered in LMICs. The significant preoperative curve correction achieved is desirable for safe surgical intervention, given the potentially life-threatening complications associated with direct surgical correction of severe spinal curves. Expanding the use of this intervention, especially in LMICs, could offer greater insights into its potential benefits and safety in these settings.

ID: 1400

A306: Development of pelvic incidence in children: cross-sectional studies cannot tell the whole story

Joel Turtle ¹ , Ndidi Njoku ¹ , Joshua Klatt ¹ , Joshua Speirs ¹

¹ University of Utah, Orthopaedic Surgery, Salt Lake City, United States

Introduction: Pelvic morphology and sagittal spinal alignment are critical to understanding spinal biomechanics, with pelvic incidence (PI) playing a key role in determining spinal curvature, posture, and overall balance. While most studies on PI in children utilize cross-sectional designs, they are limited in capturing individual growth patterns over time. This study employs a longitudinal approach to investigate changes in PI among pediatric patients, offering a more nuanced understanding of the dynamic evolution of pelvic morphology during growth. Material and Methods: We conducted a retrospective cohort study of pediatric patients treated in a multidisciplinary orthopedic clinic. Inclusion criteria required patients to have at least two lateral spine radiographs taken at least one year apart, excluding those with prior spine surgeries. PI was measured on all qualifying radiographs, with measurements performed by a single trained observer to ensure consistency. Any patients found to have a change in pelvic incidence greater than 10 degrees had all radiographs remeasured by an attending surgeon. The primary outcome was the change in PI over time, analyzed using Microsoft Excel and R, with statistical significance defined as p < 0.05. Results: Of the 3,894 patients initially reviewed, 226 met the inclusion criteria. The mean age at the time of radiograph was 11.9 years (range: 0-20 years), with an average of 2.6 radiographs per patient over a mean follow-up of 3.1 years. The average PI at age 0 was approximately 41 degrees, increasing by 0.5 degrees annually. While mean PI changes were minimal, individual variability was significant: 20 patients (8.8%) showed increases greater than 10 degrees, and 7 patients (3.1%) exhibited decreases greater than 10 degrees. For instance, one patient’s PI increased from 70 to 84 degrees over four years, while another's PI increased by 11 degrees over two years. Conclusion: Our findings reveal significant individual variability in PI changes during growth, which is masked by cross-sectional designs. These changes suggest that PI can continue evolving into adolescence, impacting spinal alignment and long-term spinal health. This study underscores the importance of individualized monitoring of PI in pediatric patients, as significant changes may predispose individuals to future degenerative spine diseases. Early identification and intervention could help mitigate biomechanical disadvantages, improving quality of life and reducing the risk of spine disorders in adulthood. Further research is needed to develop targeted interventions for patients at risk.

OP35: Spine Infections and Other Complications

ID: 1168

A307: Pott’s spine - A major challenge for spinal surgeons in developing countries. Experiences in operative management

Yawar Shoaib Ali ¹

¹ Sarvodaya Hospital and Research Centre, Sec 8, Neurosurgery, Faridabad, India

Introduction: M.tuberculosis infections of the spine continue to be a major challenge for spine Surgeons in developing countries. This challenge has recently increased in view of the emergence of multi drug resistant strains. Potts spine can cause neurological deficits and lead to progressive spinal deformity. The general surgical indications include spinal cord or nerve root compression, neurological deficits and progressive deformity. In this study, we aim to assess the efficacy of posterior decompression and fusion for Potts spine in terms of reduction in radiological compression, improvement or stability in deformity and clinical improvement in neurological function. Material and Methods: 30 consecutive patients with Pott’s spine fulfilling the criteria for surgery were included in the study. All were operated by the same surgeon in a single center. 20 patients had involvement of the dorsal spine and dorsolumbar junction, 7 had involvement of the lumbosacral region and 3 had cervical involvement. 22 patients had radiological evidence of neural compression and 11 had kyphosis. Neurodeficit was present clinically in 16 patients. All patients were operated by a posterior only approach with decompression at the affected level and pedicle screw fixation two levels above and below. Accessible pus was drained and sent for labs and tissue was also harvested for histopathological examination. All patients received anti tubercular chemotherapy post surgery for a period of 18 to 24 months. Follow up MRI was done 3 and 6 months after surgery. Results: Neurological improvement was noted post surgery in 10 patients. Radiological evidence of neural decompression was noted in 11 patients at 3 months and 17 at 6 months. No patient had further progression of kyphosis after surgery. Conclusion: Posterior decompression and fixation for Pott’s spine is a simple, elegant and relatively less risk approach for neural decompression and spinal stabilization. In conjunction with antitubercular drugs, it achieves good results and reduces the risk of progressive kyphosis and neurological impairment.

ID: 2450

A308: Anterior column reconstruction in spinal tuberculosis: obligation or overkill

Pankaj Kandwal ¹ , Siddharth Sethy ¹ , Kaustubh Ahuja ¹

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

Background: Management of spinal tuberculosis (STB) is accomplished with or without anterior column reconstruction (ACR). Literature lacks definitive indication of ACR in STB. This study attempts to find out its essentiality. Methods: A retrospective analysis of prospectively collected data of STB was carried out. Patients were divided into two groups: one where ACR were performed and one without (N-ACR). Along with basic demography, radiological parameters like vertebral body height loss (VBHL), column height loss (CHL), segmental kyphosis (SK), adjusted kyphosis (AK) were calculated. An ROC curve analysis was done to identify cut-off values, followed by subgroup analysis for each parameter. Functional outcomes were assessed by ODI at 0, 1, 6 months. Results: In total 104 patients (61 female, 43 male) mean age was 34.46 ± 17.61. 54 cases were managed operatively out of which ACR was done in 32. ROC analysis identified cut-off values for VBHL 0.65 (Sensitivity 0.758, 1-specificity 0.493), CHL 1.12 (Sensitivity 0.727, 1-specificity 0.485), SK 18° (Sensitivity 0.727, 1-specificity 0.408), and AK 25° (Sensitivity 0.788, 1-specificity 0.465). Subgroup analysis was carried out in operated patients above these cutoff values. No significant differences in ODI were noted between ACR vs N-ACR across all subgroups. Conclusion: ACR was not found to be integral for better functional outcomes in short term result. However, its translation in long-term need validation with further studies assessing potential mechanical complications.

ID: 815

A309: Evaluation of spinal deformity and its progression in pyogenic spondylodiscitis: a retrospective MRI study of 59 cases

Andreas Kramer ¹ , Jonathan Neuhoff ² , Santhosh G. Thavarajasingam ³ , Rebecca Sutherland ⁴ , Hugh McCaughan ⁴ , Benjamin Davies ⁵ , Ehab Shiban ⁶ , Florian Ringel ³ , Andreas Demetriades ⁷

¹ University Medical Center Mainz, Mainz, Germany,

² Berufsgenossenschaftliche Unfallklinik Frankfurt am Main, Frankfurt am Main, Germany,

³ University Medical Center Mainz, Department of Neurosurgery, Mainz, Germany,

⁴ Western General Hospital, Department of Infectious Diseases, Edinburgh, United Kingdom,

⁵ Addenbroke's Hospital, Cambridge University Hospital NHS Healthcare Trust, Cambridge, Cambridge, United Kingdom,

⁶ Lausitz University Medicine, Department of Neurosurgery, Cottbus, Germany,

⁷ Royal Infirmary Edinburgh, Department of Neurosurgery, Edinburgh, United Kingdom

Introduction: Pyogenic spondylodiscitis management often remains conservative without surgical intervention, yet the risk of spinal deformity under such therapy is unclear. This study explores spinal deformity progression in conservatively treated patients and identifies predictive factors for deformity advancement. Material and Methods: Retrospective cohort design with radiological data analysis from 59 patients with conservatively treated pyogenic spondylodiscitis. Deformities were categorized into four progression types reflecting severity: Type 1 (progressive vertebral body edema/endplate erosion), Type 2 (Type 1 plus disc space collapse), Type 3 (vertebral body destruction/mild translation), and Type 4 (significant segmental kyphosis > 20°/severe translation). Results: Among 59 patients, 66% exhibited progressive deformity over a mean follow-up of 10.75 months. The distribution of deformity progression was: Type 1 in two cases (3%), Type 2 in seven cases (12%), Type 3 in 13 cases (22%), and Type 4 in 17 cases (29%). Progression of deformity included a 92% increase in cases with segmental kyphosis > 20°; and a 167% increase in cases with segmental translation. Risk factors for significant kyphosis included > 50% vertebral body erosive destruction (p < 0.01) and the presence of an epidural abscess (p < 0.05). Lumbar region involvement significantly reduced the likelihood of spinal fusion at follow-up (p < 0.05). A paravertebral abscess was significantly associated with the presence of a fractured vertebrae at follow-up (p < 0.05). Conclusion: This study underscores the importance of closely monitoring patients with conservatively managed pyogenic spondylodiscitis for progressive spinal deformity, and suggests considering early surgical intervention in cases with a high risk of progression.

ID: 1588

A310: Spinal hydatidosis and how albendazole impacts postoperative recurrency risk

Wièm Mansour ¹ , Ghassen Gader ¹ , Myriam Naceur ² , Hdhili Houssem ¹ , Bahri Farah ¹ , Aziz Bedioui ¹ , Mohamed Zouaghi ¹ , Mouna Rkhami ¹ , Kamel Bahri ¹ , Mohamed Badri ¹ , Zammel Ihsen ¹

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

² National Institute of Neurology, Department of Neurosurgery, Tunis, Tunisia

Introduction: Hydatid cysts result from the development of the larval form of Echinococcus granulosus in humans. Bone involvement in hydatid disease is uncommon, even in endemic regions, and is often diagnosed only after neurological complications have arisen, due to the condition’s clinical latency and nonspecific symptoms. This study aims to assess the impact of the duration and dosage of postoperative Albendazole treatment on recurrence rates and quality of life in patients with spinal hydatid disease. Methods: We conducted a retrospective study of 10 cases of vertebral hydatidosis collected from the neurosurgery departments of the Trauma and Burn Center in Ben Arous over a 7-year period, from January 2015 to December 2022. These patients were divided into two groups based on the dosage and duration of Albendazole treatment prescribed postoperatively. Results: The average age of the patients was 40.9 years, with a male predominance. The average diagnostic delay was 6 months. The clinical presentation was dominated by pain and motor disturbances. Five patients had sphincter disorders, and five had sensory disturbances. Spinal MRI helped guide the diagnosis, determine the extent of the involvement, and assess its impact. Eight patients underwent surgery via a posterior approach, while 2 patients underwent a combined approach. Complete excision was achieved in 5 patients. The average recurrence time after surgery was 11.4 months for the first group and 27 months for the second group. Conclusions: Vertebral localization is the most common and severe form of bone involvement in hydatid disease. The bone lesions are extensive, with a very gradual progression but inevitably lead to permanent neurological complications. The severity of vertebral echinococcosis lies in the therapeutic challenges, especially in advanced stages. Although surgery remains the cornerstone of management, its often incomplete nature has led many authors to resort to high-dose, long-term antihelminthic medical treatment to prevent secondary dissemination and recurrences and to optimize therapeutic strategies.

ID: 1447

A311: The use of prophylactic antibiotic loaded calcium sulphate beads in adolescent idiopathic scoliosis posterior correction surgery

Aliénor Warr-Esser ¹ , Priyanshu Saha ¹ , Charles Taylor ¹ , James Geddes ¹ , Liam Rose ¹ , Adnan Sheikh ¹ , Hasan Raza 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: The objectives of Adolescent Idiopathic Scoliosis (AIS) correction surgery are to prevent deformity progression, spine balance, maintain neurological function, preserve spinal motion, and achieve cosmesis. Spine Surgery Infection (SSI) management is important in noninfected and infected patients. In posterior surgery, the use of antibiotic-loaded calcium sulphate beads as opposed to traditional topical antibiotic powders is an innovative means of administering topical antibiotics useful for biofilm reduction, slow continuous elution, and dead space reduction. This review looks at the safety and efficiency of antibiotic-loaded beads compared to its traditional counterpart. Material and Methods: Retrospective review of all posterior approach surgical patients for scoliosis patients between 2017 and 2023 at St George’s NHS Trust. Patient demographics; surgery approach and type; vertebral levels for posterior instrumentation; operative complications; bone graft; prophylactic antibiotic regime; washout/debridement surgery; length of postoperative stay; and infection rate were recorded. Results: 113 scoliosis posterior spinal fusion patients (82 Female, 31 Male or 2.7:1), with an average age of 17.2 ± 8.4, underwent posterior only approach (n = 100), combined (n = 4), or 2-staged (n = 9) anterior/posterior or posterior/anterior approach. The average number of levels for posterior instrumentation was 12.0 ± 3.2 (lowest:2, highest:22). 105 of the surgeries were primary and 8 revision. Prophylactic antibiotic regime to prevent SSI: calcium sulphate beads loaded with Vancomycin + Cefuroxime (n = 82). Conventional antibiotic powder (n = 31) containing Vancomycin + Gentamycin + Cephalexin (n = 21); Cephalexin + Gentamycin/Vancomycin (n = 4), Vancomycin (n = 6). 6 postoperative infections occurred that required debridement surgeries: Patients 1-5: Vancomycin + Cefuroxime loaded calcium sulphate beads. Patient 6: Vancomycin + Gentamycin + Cephalexin as powder. Conclusion: The use of antibiotic-loaded calcium sulphate beads for scoliosis correction surgery is a safe method of preventing SSI. Beads deliver local, dose-dependent, antibiotic activity even against “resistant” infections. Beads have been shown in other studies to deliver excellent biofilm reduction, slow continuous elution, and dead space reduction making it an excellent option for non-infected or infected posterior spinal surgery cases.

ID: 2662

A312: Spinal hydatid disease in a South African paediatric population

Stefan Kruger ¹ , Anthony Figaji ²

¹ University of Cape Town, Neurosurgery, Groote Schuur Hospital, Cape Town, South Africa,

² University of Cape Town, Neurosurgery, Red Cross War Memorial Children's Hospital, Cape Town, South Africa

Introduction: Hydatid disease is thought more common in children, than adults and historically the aim has been the complete surgical removal of a hydatid cyst without rupture. This is thought to be required to prevent recurrence. Surgery is then followed with anti-helminthic treatments. Cases of hydatid disease involving the spinal column affect neurological function, but also spinal stability. There is a paucity in international literature that reports on long term outcomes in children who undergo surgery for spinal hydatid disease - publications being largely limited to case reports only. Material and Methods: Records of patients who were diagnosed with spinal hydatid disease, at Red Cross War Memorial Children’s Hospital (population younger than 13 years at diagnosis), during the preceding 15 years were retrieved. Demographic variables, clinical variables, and longer-term outcomes were collected as well as referral region, clinical presentation, associated imaging features and surgical management with its outcomes. Results: Five patients were found to have been diagnosed with spinal hydatid disease. Patients generally presented with long tract signs. One patient had cervical disease, one had lumbar, two had thoracic and one patient had non-contiguous thoracic and lumbar cysts. Extraspinal hydatid was seen in two patients who both had concurrent liver cysts. Two of the five patients had repeat operations for hydatid cysts, having presented with symptomatic recurrences (paraparesis). Four patients had vertebral involvement (Braithwaite and Lees type 4); two of whom had corpectomies with spinal instrumentation. One patient had intra-dural disease only, associated with syringomyelia. One patient had a normal neurological outcome, two patients had paraparesis but were ambulant, one patient had incomplete records and was lost to follow up. All patients were treated with long term Albendazole in order to avoid recurrence. The average follow-up time per patient was 4.9 years (range 0.76 to 10.5 years). The sample showed a geographical preponderance toward rural areas of South Africa’s Eastern Cape and Western Cape provinces where sheep farming is common. Conclusion: Spinal hydatid disease is a rare clinical entity but relevant to surgeons practicing in regions where rural sheep farming is common. Patients may present with non-specific symptoms and signs. Surgical decision-making pivots on neurological function as well as long term spinal stability. In this series, complete and long-term eradication of spinal hydatid remained challenging and long term treatment with anti-helminthics appears reasonable.

ID: 1167

A313: Cutibacterium acnes infection in instrumented spine surgery: defining patterns of presentation and treatment strategies

Susana Núñez-Pereira ¹ , Lluís Vila-Castillo ¹ , Ricard Llovera González-Adrio ² , Sleiman Haddad ¹ , Julia Sellares-Nadal ³ , Juan Fernando Salom Linares ¹ , Ana García de Frutos ¹ , Manuel Ramírez Valencia ¹ , Ferran Pellise ¹ , Dolors Rodríguez-Pardo ³

¹ Vall d'Hebron University Hospital, Spine Surgery Unit, Barcelona, Spain,

² Vall d'Hebron University Hospital, Orthopaedics and Trauma Surgery, Barcelona, Spain,

³ Vall d'Hebron University Hospital, Infectious Diseases Department, Barcelona, Spain

Purpose: Cutibacterium acnes surgical site infections (SSI) in instrumented spinal surgery are an increasing concern, often unexpectedly discovered during revision surgeries in patients with poor outcomes. C. acnes SSI typically have a delayed presentation, and there is insufficient data to guide decisions regarding implant exchange versus debridement, leading to unclear treatment strategies. This study aims to describe the clinical manifestations and determine when implant exchange is necessary. Methods: A retrospective analysis was conducted on all consecutive patients who underwent instrumented spinal surgery at a single institution between 2008 and 2023, with C. acnes infections confirmed by positive cultures. A descriptive analysis of patient demographics and infection characteristics was performed. Clinical and surgical variables were also evaluated, with a focus on treatment approaches (debridement versus implant removal, with or without reinstrumentation) and associated outcomes. Results: A total of 43 cases of C. acnes SSI were analyzed, with a mean patient age of 42.4 years; 65.1% were male. SSIs were classified as early (ESSI) when presenting within six weeks of the index surgery (15 cases, 34.95%), or late (LSSI) (6.95% between six weeks and one year, and 58.1% after one year). Fractures were the most common spinal condition (32.6%), followed by degenerative and deformity conditions, both at 27.9%. Cervical involvement was more frequent in ESSI (46.7% vs 17.9%, p = 0.045), while thoracic or lumbar involvement was more common in LSSI (60.0% vs 89.3%, p = 0.024). ESSI cases were polymicrobial in 66.7%, compared to 39.3% for LSSI (p = 0.06). In 11 cases (25,6%) there was no suspicion until revision taken was made for other reason and cultures were taken based on soft tissue appearance. The mean number of levels fused was 6.1. ESSI were more likely to present with wound complications (73.3% vs 25.0%, p = 0.002), while LSSI were more commonly associated with pseudarthrosis or implant loosening (0% vs 67.9%, p < 0.001). Clinical signs of infection were present in 88.4% of patients, the most frequent were persistent pain (48.8%) and wound complications (41.9%). Radiological abnormalities were observed in 67.4% of patients, with pseudarthrosis or implant loosening identified in 44.2% and collections or abscesses found in 23.3%. Initially, 14 of 15 ESSI cases were treated with debridement and implant retention (DAIR). DAIR failed in 3 cases (21.4%); one required additional debridement, another staged implant exchange, and the third implant removal. Implant exchange was performed in 22 cases (51.2%), and 7 cases (16.3%) involved implant removal without reinstrumentation. Conclusions: C. acnes is typically associated with late, low-grade infections. The current data reveal two distinct patterns of presentation. ESSI more commonly affects the cervical spine and is associated with wound complications and a trend toward polymicrobial infections. LSSI predominantly affects the thoracolumbar region, often accompanied by radiological changes or pseudarthrosis. Improved recognition of presentation patterns and radiological signs is essential for enhancing the diagnosis and management of these infections.

ID: 2709

A314: Analysis of correlation factors between video-assisted thoracoscopic spinal surgery and postoperative pleural adhesion

Chuanjiang Li ¹ , Daniel Rosenthal ²

¹ YuYao Banger Orthopaedics Hospital, Orthopaedics, YuYao, China,

² Frankfurt Hochtaunus Kliniken, Neurospine, Bad Homburg, Germany

Introduction: A certain proportion of pleural adhesions will occur after thoracoscopic surgery, but the situation of pleural adhesions in thoracoscopic assisted spinal surgery is not clear, and the related factors of the occurrence of adhesions are also lack of relevant literature reports. This study discusses the possible factors of thoracoscopic spinal surgery and postoperative complications of pleural adhesions, and finds out the high-risk factors from them. Make correct disease prevention guidance and treatment after operation. Material and Methods: From September 2010 to September 2024, patients hospitalized at Hochtaunus Kliniken Hospital in Germany were retrospectively included as a case group due to various thoracic diseases, excluding a history of chest and lung diseases. They underwent selective video-assisted thoracoscopic surgery. All patients were diagnosed by Magnetic resonance imaging (MRI) and CT. Gender, age, BMI, smoking history, drinking history, lung function, operation time (less than 2 hours, more than 2 hours and less than 4 hours) of all participants were retrospectively collected. More than 4 hours three groups), intraoperative blood loss (less than 100 ml, more than 100 ml less than 200 ml and more than 200 ml three groups), intraoperative number of segments, whether intraoperative implants were used, postoperative bed time and other relevant information. Then Chi-square test and multi-factor logistic regression statistical analysis were performed to determine the risk factors leading to pleural adhesions. Results: A total of 896 patients who underwent surgery for various thoracic diseases were included in this study, ranging in age from 16 to 84 years, with an average age of 65.42 years. The incidence of pleural adhesions showed an S-shaped increase with age. The incidence ratio of male to female was 1:1.03, and Fisher's exact probability method (p > 0.05) showed no statistical significance. First, the statistical results of univariate Chi-square test showed that among all the included factors, BMI > 34 kg/m² (p < 0.01), smoking history (average daily smoking > 10 cigarettes) (p < 0.01), pulmonary ventilation dysfunction (p < 0.01), and operation time (less than 2 hours and more than 4 hours) (p < 0.001), the intraoperative blood loss ≥ 200 ml (p < 0.01), the intraoperative number of segments greater than three levels (p = 0.02), and the postoperative bed time greater than 3 days (p < 0.01) had significant differences. In addition, multivariate Logistic regression analysis was performed for factors with a p-value < 0.10, and the statistical results also showed that the above included variables were high risk factors for pleural adhesions. Conclusion: BMI over 34 kg/m², daily smoking over 10 cigarettes, pulmonary ventilation dysfunction, operative time over 4 hours, blood loss over 200 ml, operative segments over 3 days, and postoperative bed rest time over 3 days are high risk factors for the occurrence of pleural adhesion in thoracoscopic spinal surgery. Relevant factors can be prevented and treated. Such as improving lung ventilation function before surgery, quitting smoking before surgery, reducing operation time and blood loss during surgery, and reducing the probability of early postoperative ground activity.

ID: 741

A315: Effectiveness of prophylactic negative pressure wound therapy in reducing surgical site infections after spinal surgery in high-risk patients

Nobuaki Hattori ¹ , Akihiko Hiyama ¹ , Daisuke Sakai ¹ , Hiroyuki Katoh ¹ , Masato Sato ¹ , Masahiko Watanabe ¹

¹ Tokai University School of Medicine, Orthopedic Surgery, Kanagawa, Isehara, Shimokasuya

Introduction: Surgical Site Infection (SSI) after spinal surgery is a serious issue that must be avoided. As a preventive measure against SSI, the WHO guidelines recommend prophylactic Negative Pressure Wound Therapy (pNPWT) for high-risk patients. This study reports the use of pNPWT at our facility and evaluates its effectiveness. Material and Methods: Between 2023 and 2024, 53 spinal surgery patients (31 males, 22 females, mean age 68.1 years) who used pNPWT were evaluated. These patients were considered high-risk, meeting one or more criteria: BMI > 30, HbA1c > 7.0, steroid therapy, dialysis, immunodeficiency, malnutrition, skin disease, or revision surgery. The survey items included diagnosis, operative time, blood loss, CRP level on postoperative day 7, site of use, reason for use, length of hospital stay, and occurrence of SSI during hospitalization. Results: The cohort included 20 patients with lumbar degenerative disease, 18 with adult spinal deformity, 8 with cervical spine disease, 2 with spinal cord tumors, 2 with idiopathic scoliosis, 2 with pyogenic spondylitis, and 1 with a postoperative infection. The mean operative time was 177 minutes, the mean blood loss was 206 ml, and the mean CRP level on postoperative day 7 was 3.4 mg/dL. pNPWT was applied in 2 anterior approaches to the cervical spine, 6 posterior approaches to the cervical spine, 4 posterior approaches to the thoracic spine, 29 posterior approaches to the lumbar spine, and 12 posterior approaches to the thoracolumbar spine. The reasons for pNPWT application included HbA1c > 7.0 in 11 patients, skin disease in 10 patients, malnutrition in 8 patients, immunodeficiency in 7 patients, revision surgery in 6 patients, steroid use in 5 patients, and dialysis and BMI > 30 in 3 patients each. The average length of hospital stay was 25 days, and SSI occurred in 1 patient (1.9%). This patient was undergoing steroid therapy for rheumatoid arthritis, had malnutrition, and had undergone posterior approaches to the thoracolumbar surgery. Conclusion: In this study, the incidence of postoperative SSI was only 1 patient among high-risk patients who received pNPWT. pNPWT as a postoperative dressing is expected to reduce the risk of SSI. However, further studies are needed to evaluate the cost-effectiveness and clinical criteria for applying pNPWT.

OP36: Navigation and Robotics 2

ID: 2088

A316: Intraoperative radiation exposure for patients and surgical teams in percutaneous thoracolumbar pedicle screw placement: comparing computer-assisted navigation and fluoroscopic guidance

Eric Mandelka ^1,2 , Jula Gierse ^1,2 , Anna Wagner ^1,2 , Paul Alfred Grützner ^1,2 , Sven Vetter ^1,2

¹ BG Klinik Ludwigshafen, Department of Trauma Surgery and Orthopedics, Ludwigshafen, Germany,

² University of Heidelberg, Heidelberg, Germany

Introduction: Over the last decade, pedicle screw placement with computer-assisted navigation (CAN) has become increasingly common in spine surgery. While literature almost unequivocally suggests CAN reduces radiation exposure to the surgical team compared to conventional fluoroscopic guidance (FG), the results regarding patient radiation exposure vary. This variability is likely due to the use of different imaging modalities, low-dose protocols, and differences in surgical procedures studied. This study aimed to analyze intraoperative radiation exposure to both the patient and the surgical team during percutaneous pedicle screw placement (PPSP) using CAN versus FG. Material and Methods: This is a matched pair subanalysis of a patient cohort from a prospective randomized trial comparing thoracic and lumbar PPSP with CAN or FG. Matching was performed by levels instrumented and number of screws placed. To create a homogeneous cohort, patients with additional intraoperative procedures (e.g. laminectomy) or open surgery were excluded. The same mobile C-arm cone beam computed tomography (CBCT) with identical settings was used in both groups. The primary outcome parameter was the radiation exposure per screw placed. The patient effective dose (ED) was calculated from the dose area product of the CBCT dose protocol using a BMI-dependent conversion factor. For the lead surgeon (LS), the assistant surgeon (AS), and the scrub nurse (SN), the cumulative ED was determined using live dosimeters attached to the lead gown at the upper chest. Results: 23 patient pairs with a total of 174 screws placed in each group were included. Patients in the CAN group were significantly older (p = 0.04), while there were no significant differences regarding patient sex and BMI. An intraoperative 3D scan was performed in 8 patients in the FG group compared to all patients in the CAN group (11 patients with 1 scan, 11 patients with 2 scans, 1 patient with 3 scans; p < 0.001). In general, the patient ED was significantly higher in the CAN group (4,283 ± 2,236 versus 2,792 ± 3,113 µSv; p = 0.03). In contrast, ED was significantly higher in the FG group than in the CAN group for the LS (47.4 ± 53.3 vs. 20.7 ± 36.2 µSv; p < 0.001) and the AS (25.3 ± 27.2 vs. 11.1 ± 16.9 µSv; p = 0.008), but not for the SN (6.5 ± 13.6 vs. 3.84 ± 3.96 µSv; p = 0.16). Accordingly, the European guidelines for occupational radiation protection (20,000 µSv per year) would limit the LS to 421 procedures per year using FG versus 966 procedures using CAN. Conclusion: This study highlights the implications of CAN for both patient and occupational radiation exposure. For the patients, the average intraoperative radiation exposure was below the dose of a lumbar CT scan (5,000 to 7,500 µSv according to the literature). Although the average radiation exposure to the surgical team in both groups is well below regulatory limits, no exposure level entirely eliminates radiation risk, particularly with long-term exposure in mind. In summary, CAN may be an effective method to reduce occupational radiation exposure. In addition, if postoperative CT imaging can be reduced by performing intraoperative 3D scans, CAN may even result in lower patient radiation exposure.

ID: 2741

A317: Comparison of free-hand technique, O-arm navigation and robot-assisted pedicle screw placement in the lumbar spine: a single-centre, triple-arm, double-blinded, prospective randomized controlled trial

Nishank Mehta ¹ , Bhavuk Garg ¹ , Sauma Shankar Dey ¹

¹ All India Institute of Medical Sciences, New Delhi, India

Introduction: Pedicle screw fixation is the cornerstone of modern of spine surgery but carries a risk of adverse events related to malpositioning and misplacement. Image-guided navigation provides real-time visualization of the trajectory and subsequent implant placement in three planes with potential implications on safety and accuracy. The addition of a rigid, robotic arm has purported benefits of reducing fatigue-related errors. The present study aims to compare the safety and accuracy of pedicle screw placement in the lumbar spine using three techniques: i) conventional free-hand technique, ii) using O-arm guided navigation and, iii) using robotic assistance. Materials and Methods: A single-centre, triple-arm prospective randomized controlled trial was conducted recruiting patients with lumbar degenerative spine disorders planned for single-level or two-level transforaminal lumbar interbody fusion (TLIF), which involved placement of lumbar pedicle screws. The patients were randomized between three techniques for pedicle screw placement: i) conventional free-hand technique, ii) using O-arm guided navigation and, iii) using robotic assistance. A total of 100 screws (50 pairs) were placed under each arm of the study group. The outcome assessor as well as the patient were both blinded to the study group allocation. The primary outcome was the number, direction (superior/inferior/medial/lateral) and grade of pedicle wall breach utilizing the Gertzbein and Robbins system (GRS). The secondary outcome measures were the insertion time for each pedicle screw (minutes), radiation exposure and incidence of complications directly attributable to pedicle screw malpositioning. An intention-to-treat analysis was performed and every case where O-arm navigation or robot-assisted screw placement had to be converted to conventional free-hand technique was documented. Results: The overall accuracy of pedicle screw placement (no breach) was 91% for the conventional free-hand technique, 96% for O-arm navigation and 96% for robot-assisted technique. Both O-arm navigated and robot-assisted screw placement resulted in a significantly lower incidence of total number of pedicle breaches and the number of medial pedicle wall breaches when compared to the conventional free-hand technique – the number of superior, inferior and lateral pedicle wall breaches was comparable between all three groups. There was no instance of GRS-D (> 4 mm) breach with either O-arm navigation or robot-assisted screw placement. Furthermore, the use of O-arm navigation resulted in a significantly lesser incidence of cranial facet violation when compared to conventional free-hand or robot-assisted techniques. The mean insertion time was significantly lower for the conventional free-hand technique (1.12 ± 0.30 mins) compared to O-arm navigation (1.88 ± 0.78 mins) and robot-assisted (3.58 ± 0.98 mins). Only one patient in the conventional free-hand technique group had a complication (foot drop, L4 nerve root palsy) that could be attributed to pedicle screw malpositioning. Conclusions: Both O-arm navigation and robot-assisted techniques decrease the incidence of medial pedicle wall breach in patients undergoing lumbar pedicle screw fixation – however, the improved accuracy comes at the cost of adding to the surgical time. To answer whether the improved accuracy leads to superior outcomes, better biomechanical purchase or decreases the incidence of clinical complications requires a study with a larger sample size.

ID: 1808

A318: Usefulness of neuronavigation for the resection of vertebral osteoid osteoma: a case series of seven patients

Alvaro Silva ^1,2 , Andres Lisoni ^1,2 , Manuel Valencia Carrasco ^1,3 , Ernesto Pino ⁴ , Nicolás Rotman Hinzpeter ¹

¹ Clinica Alemana de Santiago - Universidad del Desarrollo, Spine Surgery, Santiago, Chile,

² Hospital Clínico de la Fuerza aérea de Chile, Spine Surgery, Santiago, Chile,

³ Mutual de Seguridad CChC, Spine Surgery, Santiago, Chile,

⁴ Clinica Alemana de Santiago - Universidad del Desarrollo, Traumatology and Orthopaedics, Santiago, Chile

Introduction: Osteoid osteoma (OO) is an uncommon tumor in the spinal region, and when surgical intervention is warranted, en bloc resection is the most advocated approach according to existing literature, due to the intraoperative difficulty in visualizing the nidus. The utilization of intraoperative tomography in conjunction with neuronavigation has enhanced the ability to visualize the tumor's location, boundaries, and thereby to delimit and facilitate its resection. This is a descriptive retrospective study, presenting a case series. The aim is to elucidate the technical considerations and clinical outcomes associated with the application of neuronavigation in the management of vertebral OO in seven patients. Material and Methods: The study outlines the diagnostic process, the assessment of the anatomical positioning of the OO, and the decision-making involved for the surgical technique. The methodology for excising the nidus is described, highlighting the delineation of tumor-free margins facilitated by navigation based on intraoperative tomography. Postoperative clinical outcomes, follow-up data, and histopathological findings are also reported. Results: Out of the identified lesions, 5 were located in the thoracolumbar posterior arch, while 1 was situated in the posterior aspect of the vertebral body of C3, and another in the left lateral mass of C2 near the vertebral artery. A vertebral artery occlusion test was performed on the latter patient prior to surgical intervention. In all 7 patients, the nidus was accurately identified via intraoperative tomography. In 4 of the 5 patients with lesions in the posterior arch (all located in the joints), an intralesional resection was performed with at least 1 mm margins, obviating the need for spinal fusion. In the fifth patient with a thoracolumbar lesion, a 4-mm resection trocar was utilized to achieve complete excision of the nidus. For the patient with the lesion in the posterior aspect of the C3 vertebral body, a partial resection of the lower half was executed, including the nidus, and reconstruction was achieved using a custom-cut iliac crest graft. The patient with the lesion in the left lateral mass of C2 underwent a wide approach, and the nidus was identified using navigation. It was resected intralesionally with a 1 mm radiological margin. To manage bleeding from the adjacent vertebral artery, vascular clips were applied. Postoperative angiography showed vertebral artery occlusion without clinical consequences, attributable to the preoperative occlusion test. The histopathological analysis confirmed OO in all seven patients. No complications or iatrogenic instability were observed. Furthermore, no recurrences were noted during a minimum follow-up period of 18 months. All patients reported complete pain relief. Conclusion: Intraoperative tomography is capable of visualizing the nidus. In this cohort, the application of neuronavigation allowed accurate localization and resection of OO, preserving spinal stability in the thoracolumbar region and avoiding the necessity for corpectomy in the cervical spine. The integration of intraoperative tomography and navigation facilitates the identification of small lesions, enables the achievement of appropriate resection margins, and allows for limited resections without causing spinal instability.

ID: 2254

A319: 15-year analysis of the accuracy of 4,814 thoracolumbar pedicle screws inserted using intraoperative navigation

Pirateb Sundaram ¹ , Kevin Anthony Chong ¹ , Shao-Rong Alexander Pang ² , Joanne Lim ² , Jacob Oh ¹

¹ Tan Tock Seng Hospital, Singapore, Singapore,

² National University of Singapore, Singapore, Singapore

Introduction: 3D intraoperative imaging and navigation continue to be used as an adjunct in spinal instrumentation, aiming to enhance the accuracy of pedicle screw insertion. The study aims to analyse the accuracy of routine thoracolumbar pedicle screw insertion using O-arm navigation over a 15-year period, as well as report on any complications encountered and revisions that were performed. Material and Methods: A retrospective analysis was conducted on patients who underwent thoracolumbar pedicle screw insertion using intraoperative imaging and navigation between 2009 and 2023. Post-instrumentation O-arm spin images were obtained and analysed for pedicle screw breaches. The Gertzbein classification was used to grade the pedicle screw breaches. The breach rate and screw revision rate were computed thereafter. Results: 4,814 thoracolumbar pedicle screws were inserted using intraoperative navigation during the period of this study. There was a 98.36% insertion accuracy of the thoracolumbar screws. The rate of major breach was 0.19% and the rate of intraoperative screw revision was 0.44%. There was no incidence of returns to the operating theatre for the revision of screws. Conclusion: This study is the largest review of accuracy of intraoperative navigation to date. Intraoperative navigation is highly accurate for the insertion of thoracolumbar pedicle screws. This paper provides continued support of regular use of intraoperative imaging and navigation for consistently precise pedicle screw placement.

ID: 2940

A320: Assessing the impact of intraoperative image-guided spinal navigation technologies in endoscopic lumbar spine surgery: a systemic review and meta-analysis

Max Meng-Huang Wu ¹ , Yu-Che Wang ¹ , Hsu-I Chou ¹ , Rafael Garcia de Oliveira ² , Abhinav Sharma ² , Don Park ²

¹ Taipei Medical University Hospital, Department of Orthopaedics, Taipei City, Taiwan,

² UC Irvine School of Medicine, Department of Orthopaedic Surgery, Orange, United States

Introduction: This study aimed to evaluate whether the use of intraoperative image-guided navigation provides perioperative and clinical advantages in endoscopic lumbar spine surgery (ELSS). Material and Methods: We searched the databases of PubMed, Europe PMC, Scopus, Cochrane Library, and ClinicalTrials.gov for articles comparing intraoperative image-guided navigation with conventional C-arm fluoroscopy in patients undergoing ELSS. Outcomes included perioperative outcomes such as operation time, puncture attempts, cannulation time and radiation dose; clinical outcomes such as length of stay, visual analog scale (VAS) score, Oswestry Disability Index (ODI). Results were summarized using the mean difference (MD) or standardized mean difference (SMD) with accompanying 95% confidence intervals (CI). Results: Seventeen studies (1,296 patients) were included in the meta-analysis. Intraoperative image-guided navigation in ELSS had significantly shorter total operation time (MD, -12.20 minutes; p < 0.0001), fewer puncture attempts (MD, -2.45 times; p = 0.0179), shorter cannulation time (MD, -12.59 minutes; p = 0.0003), lower radiation dose (SMD, -4.18; p < 0.0001), fewer fluoroscopy times (MD, -16.47 times; p = 0.0116), shorter length of hospital stay (MD, -0.46 days; p = 0.038) compared with C-arm fluoroscopy. There were no differences in VAS for back, VAS for leg or ODI up to 1 year of follow-up. No major complications were reported in either group. Conclusion: Intraoperative image-guided navigation in ELSS has been demonstrated to be an effective and safe technique with improvements in total operation time and radiation exposure that bring benefits to patients, surgical teams and health systems. It may also shorten the surgeon's learning curve compared with conventional C-arm fluoroscopy.

ID: 84

A321: Accuracy and efficiency of navigated cervical pedicle screw placement: a comparative analysis regarding experience levels

Jula Gierse ^1,2 , Kevin Klockow ^1,2 , Eric Mandelka ^1,2 , Benno Bullert ^1,2 , Paul Alfred Grützner ^1,2 , Sven Vetter ^1,2

¹ BG Klinik Ludwigshafen, Trauma and Orthopaedic Surgery, Ludwigshafen am Rhein, Germany,

² University of Heidelberg, Heidelberg, Germany

Introduction: Surgical treatment of cervical injuries using pedicle screws poses significant challenges due to inherent risk of injury to nerves and blood vessels. Although research indicates that navigation improves the accuracy of screw placement, data on the usability subject to surgical experience is scarce. This study aims to compare two surgeons with different levels of experience regarding accuracy and time demand of navigated cervical pedicle screw placement. Methods: In this experimental single center study navigated cervical pedicle screw placement was performed on human specimens by two surgeons. The same C-arm CBCT (cCBCT) based navigation system was used by both surgeons. One was an experienced spine surgeon (ES) and the second was a resident in trauma and orthopedic surgery with limited experience in spine surgery and navigation (RS). Screw position was assessed in cCBCT scans and rated according to Bredow. Grade 1 and 2 were considered accurate (perforation < 2 mm, and/or perforation of the transverse foramen of < 50% of the screw diameter). Additionally, time demand for screw placement was measured and compared. Results: A total of 56 cervical pedicle screws were placed, 28 by each surgeon. Out of the screws placed by the ES, three screws showed a perforation of Grade 3 or higher, resulting in an overall accuracy of 89.3%. Of the 28 screws placed by the RS four were rated Grade 3 or higher, resulting in an accuracy of 85.7%. Time demand per screw placement was 2.6 min range 16.1 min for the ES, while it was 5.9 min range 14.6 min for the RS. Statistical analysis showed no significant difference between the two surgeons regarding accuracy achieved (p > 0.99), while the difference in time demand was significant (p < 0.001*). Conclusion: The results of this study show that an experienced spine surgeon can achieve highly accurate cervical pedicle screw placement using intraoperative navigation. Accuracy reached by the resident surgeon in this study was promising, suggesting an intuitive application of the navigation system used. Nonetheless a significant difference in time demand underlines the pivotal role of experience in cervical pedicle screw placement and the application of intraoperative navigation. Sample size should be increased to determine potential significance regarding the difference in accuracy.

ID: 2695

A322: Experience with inserting percutaneous pedicle screws (PPS) using 3D C-arm and navigation: innovations in attaching a reference frame to PPS and its accuracy

Nodoka Manabe ¹ , Sho Ishiwata ¹

¹ East Maebashi Orthopaedic Hospital, Department of Orthopaedic Surgery, Maebashi, Japan

Objective: This report discusses our experience with inserting PPS using a 3D C-arm and navigation system, capable of constructing intraoperative three-dimensional images. While it is common to place reference frames (RF) on spinous processes or the pelvis using pins or clips, we also implemented a method to attach the RF directly to the inserted PPS, which is reported here. Subjects: We included 140 cases undergoing LLIF for lumbar degenerative scoliosis, degenerative spondylolisthesis, and lumbar spinal stenosis (68 males, average age 70 ± 10 years, BMI 25 ± 5). Methods: The subjects were divided into two groups: the C-arm group, which utilized only the C-arm, and the 3D-Navi group, which employed the 3D C-arm and navigation system. We compared the following parameters for each intervertebral level: (1) operation time, (2) blood loss, (3) fluoroscopy time, and (4) occurrence of perioperative transfusion. The 3D-Navi group was further divided into two subgroups based on the use or non-use of a novel RF attached to the PPS. We measured radiation exposure indicators: (X) area Air Kerma (Gycm²), (Y) cumulative Air Kerma (mGy), and (Z) the number of CT-like images taken. We verified the accuracy of PPS insertion using postoperative CT images. Results: The 3D-Navi group showed a significant reduction in fluoroscopy time, with a tendency for shorter fluoroscopy times when using the RF attached to the PPS. Although there was no significant difference in (X) or (Y), the number of CT-like images taken was fewer and more stable in the RF group. The accuracy of PPS insertion was higher in the 3D-Navi group. Discussion: Compared to the C-arm alone, there was no significant difference in operation time or blood loss, while fluoroscopy time was reduced. The benefits of placing the RF on the PPS include: (1) stable placement unaffected by the quality of the spinous process or pelvic bone, (2) applicability even when multiple pedicle screws are inserted in adjacent vertebrae, and (3) potential adaptability to alignment changes compared to pelvic placement. Our findings suggest that using a reference frame that can be attached to the PPS with 3D C-arm and navigation systems may help reduce occupational radiation exposure.

ID: 96

A323: Navigated guided C-arm free MIS-TLIF

Masato Tanaka ¹

¹ Okayama Rosai Hospital, Orthopedic Suegry, Okayama, Japan

Background: Minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) is a widely utilized technique in spine surgery. This study compares the efficacy and safety of MIS-TLIF performed with traditional C-arm fluoroscopy and C-arm free O-arm navigation. To the best of our knowledge, our study is the first to compare cage positioning between C-arm free and C-arm techniques for MIS- TLIF. Methods: A retrospective, comparative analysis was conducted on 43 patients undergoing MIS-TLIF. The group was divided based on the utilization of C-arm fluoroscopy or C-arm free O-arm navigation. Key parameters analyzed included cage orientation, screw insertion accuracy, operative efficiency, and postoperative recovery. Radiographic measurements were used to assess surgical precision, and perioperative complications were documented. Results: The study encompassed 43 patients, with no significant differences in demographic characteristics between the two groups. Surgical time and blood loss were comparable between C-arm free and C-arm groups. O-arm navigation significantly reduced pedicle screw misplacement (p = 0.024). Cage positioning differed between groups (p = 0.0063): O-arm cages were mostly mid-center, while C-arm cages were more anterior-center. No significant differences were observed in postoperative complications (screw loosenings, dural tears, surgical site infections) between groups. The Oswestry Disability Index scores at final follow-up showed no significant difference between the O-arm and C-arm groups, indicating similar levels of postoperative disability. Conclusion: C-arm free MIS-TLIF significantly improves screw placement accuracy while maintaining comparable cage placement and reducing radiation exposure. This suggests its potential as a valuable tool for safer and more precise spinal fusion surgery.

Keywords: Spine surgery, MIS-TLIF, C-arm free, O-arm, Navigation

ID: 2915

A324: Time efficiency and radiation reduction in LLIF procedures using x-ray tracking: a comparative study of 100 levels

J. Alex Thomas ¹ , Emily Oettinger ¹

¹ Atlantic Brain and Spine, Wilmington, United States

Introduction: Lateral Lumbar Interbody Fusion (LLIF) is a widely used minimally invasive procedure associated with a significant radiation exposure to the staff and patient but with few if any commonly accepted navigation options. Fluoroscopy-based instrument tracking technology has been shown to decrease radiation exposure up to 90% while improving operative times¹, but has not been explicitly studied for lateral surgery. This multicenter study aims to evaluate the efficiency of instrument tracking technology in limiting LLIF retractor time as well as radiation exposure. Materials and Methods: A consecutive series of 100 LLIF levels across 90 patients using x-ray tracking technology and 28 LLIF levels across 20 patients using conventional fluoroscopic imaging were performed by two surgeons. LLIFs that required angled instrumentation were excluded. Data on elapsed time, radiation exposure, and number of x-rays for both skin incision to skin closure (skin-to-skin) and retractor placement to retractor removal (retractor) were then recorded, compared, and analyzed using a spreadsheet application. Results: The average retractor time using instrument tracking (12.3 minutes, range 5.0 - 27.5) was significantly shorter (p < 0.001) than conventional methods (14.9 minutes, range 8.1-29.5), a decrease of 17.7%. Using instrument tracking, the surgeons were 60% more likely to stay under a 20 minute retractor time. There was no significant difference (p = 0.12) between the average skin-to-skin time using instrument tracking (16.8 minutes, range 6.7-31.3) and conventional methods (18.1 minutes, range 12.3-26.2). The average number of x-rays taken using instrument tracking (11.5, range 2-35) was significantly shorter (p < 0.001) than conventional methods (44.6, range 28-76), a decrease of 74.3%. Conclusion: The adoption of x-ray tracking in LLIF procedures significantly reduces radiation exposure to the surgical staff and patient. Additionally, x-ray tracking reduces retractor time, which has been shown to be an independent predictor of neurological complications with LLIFs². Therefore, the use of x-ray tracking can not only substantially decrease the radiation risks associated with MIS spine surgery, but also potentially decrease a key morbidity of lateral lumbar interbody fusion.

References

1. Wang TY, Hamouda F, Sankey EW, Mehta VA, Yarbrough CK, Abd-El-Barr MM. Computer-Assisted Instrument Navigation Versus Conventional C-Arm Fluoroscopy for Surgical Instrumentation: Accuracy, Radiation Time, and Radiation Exposure. AJR Am J Roentgenol. 2019;213(3):651-658. doi:10.2214/AJR.18.20788

2. Uribe JS, Isaacs RE, Youssef JA, et al. Can triggered electromyography monitoring throughout retraction predict postoperative symptomatic neuropraxia after XLIF? Results from a prospective multicenter trial. Eur Spine J. 2015;24 Suppl 3:378-385. doi:10.1007/s00586-015-3871-8

OP37: Spine Trauma Surgical 3

ID: 1190

A325: Functional outcome and safety of expansion duroplasty in traumatic spinal cord injury

Shahid Ali ¹ , Muhammad Jawad Saleem ¹ , Abubakar Atiq Durrani ¹

¹ Orthopedic Spine Institute, Spine Surgery, Orthopedic Sugery, Lahore, Pakistan

Introduction: Expansion Duroplasty (ED) effectively improves physiological parameters in Traumatic Spinal Cord Injury. Here we are presenting functional outcome and safety of ED in Acute Traumatic Spinal Cord Injury (ATSCI). Material and Methods: This prospective case series was conducted at Orthopedic Spine Institute, Doctors Hospital Medical Centre, Lahore from 1st January 2019 to 31 December 2021. Patients presented in our hospital with ASIA A after ATSCI recruited in the study and followed prospectively. All patients had ASIA scoring, x-ray screening, CTSCAN and MRI. Facia lata graft was used for ED. All patients kept flat for 5 days after surgery. The results were evaluated using ASIA scoring system preoperatively, in immediate post operative period and in follow-up visits. Patients were followed up at 3weeks, 6 weeks, 12 weeks, 6 months and 12 months post-operatively. Results: 10 patients recruited in the study. There were 7 males and 3 females while Mean age was 25 years. The mean follow up was 12 months. Patients with ASIA score B,C,D,E were excluded from study. All patients were operated within 36hours after presentation in hospital. There was no evidence of worsening of neurology after surgery. There were six patients with thoracolumbar trauma while four patients had cervical spine injury. One patient with cervical spine injury recovered and walking with assistive device at 12months. One patient with cervical spine injury regained sensory and motor of upper limbs while other two cervical spine injuries remain unchanged. Two patients with thoracolumbar trauma were independent mobilizer by the end of one year and one patient regained sensory. Two patients in thoracolumbar group remain unchanged. Average operation time was 4hours for Thoracolumbar and 6hours for cervical spine. One patient had superficial wound infection while there was no deep infection, meningitis or dural leackage. Conclusion: So it is concluded that ED is not associated with neurological injury and effectively improves neurology. However further studies are warranted.

Keywords: Acute Traumatic Spinal Cord Injury(ATSCI),Expansion Duroplasty (ED)

ID: 383

A326: Risk factors for in-hospital in cervical spinal cord injuries: a nationwide, cross-sectional analysis of concomitant injuries, comorbidities, and treatment strategies in 4.008 cases

Melanie Schindler ^1,2,3 , Jonas Krueckel ¹ , Josina Straub ¹ , Sebastian Siller ⁴ , Maximilian Kerschbaum ¹ , Dietmar Dammerer ^2,3 , Volker Alt ¹ , Siegmund Lang ¹

¹ University Hospital Regensburg, Trauma Surgery, Regensburg, Germany,

² University Hospital Krems, Department of Orthopaedics and Traumatology, Krems, Austria,

³ Karl Landsteiner University of Health Sciences, Krems, Austria,

⁴ University Hospital Regensburg, Neurosurgery, Regensburg, Germany

Background: Cervical spinal cord injuries (CSCIs) present challenges with potential severe neurological complications. Despite advances in care, in-hospital mortality remains a concern. This study explores the impact of patient-related factors and therapeutic strategies on in-hospital mortality in individuals with CSCIs. Methods: In this cross-sectional study (2019–2022), we utilized data from the German Diagnosis Related Groups system to analyze main diagnoses, patient demographics, concomitant diagnoses (ICD 10), and procedures (OPS). Data specific was extracted from the German InEK GmbH database. Differences in comorbidities and injuries were analyzed using the Chi-square test. Odds ratios (OR) were used to analyze potential risk factors for in-hospital mortality. Results: Among the 4.008 cases, with an average length of hospital stay of 61 ± 69 days, 28% (n = 939) were classified at patient clinical complexity level (PCCL) Level 0, and 25% (n = 830) at Level 3. 38% (n = 1.458) of the cases were treated in a general hospital (≥ 300 beds) and 29% (n = 1.132) in a university hospital (≥ 800 beds). In the analysis of 4.008 hospital admission cases, an in-hospital mortality rate of 8.9% (n = 355) was observed. The patient cohort demonstrated a male predominance at 72.8%, with a higher male mortality rate (n = 257, 72.4%). 64.01% of the cases were aged over 60 years and they presented a significant risk factor for increased mortality (OR 1.95; p < 0.001). Vertebral fractures at the levels C5 and C6 were the most common concomitant spinal injuries (0.16%), while concomitant fractures at C1 and C2 were associated with a significant risk for mortality (OR 3.05, p < 0.001; OR = 2.45, p < 0.001). Pneumonia occurring after 48 hours of hospitalization was associated with an increased risk (OR 2.03, p > 0.001). Amongst others, acute kidney failure, acute respiratory insufficiency, and atrial fibrillation were found to have a significant association with mortality. Additional traumatic subdural hemorrhage occurred in 0.2% of cases, correlating with elevated mortality (OR 2.21, p = 0.01). The need for blood transfusion was associated with a high mortality rate of 30% risk (OR 2.31, p > 0.001). 55.9% of cases underwent operative intervention, with the remainder opting for conservative management. Discussion: Concomitant injuries and comorbidities indicating frailty and medical complications increase in-hospital mortality risk. The study highlights the need for thorough health assessments in patients CSCIs, encouraging personalized and optimized treatment strategies.

ID: 521

A327: Long-term outcomes and predictors of neurological recovery in patients with cervical spinal cord injury: a population-based cohort study

Victor Gabriel El-Hajj ¹ , Vasilios Stenimahitis ¹ , Erik Edström ¹ , Adrian Elmi Terander ¹

¹ Karolinska Institutet, Stockholm, Sweden

Introduction: Spinal Cord Injury (SCI) encompasses a spectrum of trauma-induced impairments to the spinal cord, affecting sensory, motor, and autonomic functions. Each year, SCI affects approximately 250,000 to 500,000 people globally, with a prevalence that continues to grow. While incidence rates demonstrate regional variance, falls and road traffic accidents remain the primary cause. Material and Methods: This retrospective study analyzed prognostic factors for neurological improvement and ambulation in 194 adult patients (≥ 15 years) with traumatic cervical spinal cord injuries treated at the neurological SCI unit (SCIU) at the Karolinska University Hospital Stockholm, Sweden, between 2010-2020. The primary outcome was American Spinal Injury Association Impairment Scale (AIS) improvement, with secondary focus on ambulation restoration. Results: Results showed 41% experienced AIS improvement, with 51% regaining ambulation over a median follow-up of 3.7 years. Significant AIS improvement (p < 0.001) and reduced bladder/bowel dysfunction (p < 0.001) were noted. Multivariable analysis identified initial AIS C-D (< 0.001), central cord syndrome (p = 0.016), and C0-C3 injury (p = 0.017) as positive AIS improvement predictors, while lower extremity motor score (LEMS) (p < 0.001) and longer ICU stays (p < 0.001) were negative predictors. Patients with initial AIS C-D (p < 0.001) and higher LEMS (p < 0.001) were more likely to regain ambulation. Finally, older age was a negative prognostic factor (p = 0.003). Conclusion: This study highlights the importance of the initial injury severity for the long-term prognosis in cervical SCI, while it simultaneously reveals the recovery potential that exists even in severe cases. It underscores the critical role that individualized rehabilitation efforts play in supporting meaningful recovery and in improving patient outcomes.

ID: 1175

A328: Do the postoperative outcomes and complications justify the choice of the posterior cervical surgical technique: craniocervical fusion versus posterior atlantoaxial fusion

Anas Dyab ¹ , Maxime Raket ¹

¹ Centre Hospitalier de Luxembourg, Luxembourg, Luxembourg

Introduction: C2 fractures, particularly in elderly patients, present a significant clinical challenge due to the complexity of the cervical spine and the increased risk of complications associated with aging. Surgical intervention is often required to ensure stability and promote fusion, with posterior atlantoaxial fusion and craniocervical fusion being two commonly employed techniques. Each approach has its own set of advantages and potential drawbacks, making the choice of surgical method crucial for optimizing patient outcomes. This study aims to provide a comparative analysis of these two surgical techniques, focusing on fusion rates and surgical outcomes, to guide clinical decision-making in the management of C2 fractures in the elderly population. By evaluating the efficacy and safety of posterior atlantoaxial fusion versus craniocervical fusion, we seek to offer insights that can enhance patient care and improve surgical results. Material and Methods: A retrospective analysis was conducted on elderly patients who underwent either posterior atlantoaxial fusion or craniocervical fusion for C2 fractures. Patient demographics, surgical details, fusion rates, and postoperative complications were recorded. Fusion was assessed using radiographic evidence, while surgical outcomes were evaluated based on operative time, blood loss, and length of hospital stay. Results: The study included 43 patients, with 22 undergoing posterior atlantoaxial fusion and 21 undergoing craniocervical fusion. The fusion rate was significantly higher in the craniocervical fusion group (95%) compared to the posterior atlantoaxial fusion group (90%). However, the posterior atlantoaxial fusion group had shorter operative times and less intraoperative blood loss. Postoperative complications were more frequent in the craniocervical fusion group, including higher rates of infection and hardware failure. Conclusion: While craniocervical fusion demonstrates a higher fusion rate, posterior atlantoaxial fusion offers advantages in terms of shorter operative times and reduced intraoperative blood loss. The choice of surgical technique should be tailored to the individual patient’s condition, considering both the potential benefits and risks.

ID: 295

A329: Timing of surgery for children and adolescents sustaining complete traumatic spinal cord injury

Armaan Malhotra ¹ , Ahmad Essa ² , Ahad Jassani ³ , Husain Shakil ¹ , Jetan Badhiwala ¹ , Jennifer Quon ¹ , George Ibrahim ¹ , Jennifer Dermott ¹ , David Lebel ¹ , Abhaya Kulkarni ¹ , Avery Nathens ¹ , Jefferson Wilson ¹ , Christopher Witiw ¹

¹ University of Toronto, Toronto, Canada,

² Shamir Medical Center, Zerifin, Israel,

³ Royal College of Surgeons Medical School, Dublin, Ireland

Introduction Spinal cord injury (SCI) trials have historically underrepresented pediatric patients. There are limited pediatric data examining the influence of surgical timing on complications and mortality for children and adolescents sustaining complete traumatic SCI (despite strong evidence for adults). We therefore sought to assess the association between early surgical intervention (< 24 hours) with occurrence of hospital complications and mortality for children with complete traumatic SCI. Secondarily, we sought to determine patient, injury and hospital factors associated with timing of surgical intervention as well as to examine differences between an earlier time threshold of surgery performed within 12 hours compared to 12- 24 hours. Material and Methods: The following multicenter cohort study used Trauma Quality Improvement Program data from 2010-2020. We identified pediatric patients (age < 18) that sustained complete traumatic SCI and underwent surgical intervention within 7 days of admission. Propensity score matching was performed between patients operated within 24 hours versus > 24 hours. We then determined assessed differences for the following outcomes: major in-hospital complications, immobility-related complications, length-of-stay (LOS) and mortality. Results: There were 837 patients with complete traumatic SCI managed across 297 trauma centers identified for study inclusion (70% underwent early surgery). After matching, 494 patients were available for analysis. Patients undergoing delayed surgery experienced longer intensive care unit LOS (3.74 days, 95% CI:0.91 to 6.57 days) and more major in-hospital complications (OR 1.77, 95% CI:1.16 to 2.73) and immobility-related complications (OR 2.09, 95% CI:1.25 to 3.56). There were no differences in mortality between groups. Younger age, non-white race, penetrating injuries, lower Glasgow Coma Scale score at admission, severe concomitant abdominal injuries, and motor vehicle collision injury mechanisms were associated with increased time to surgery. Conclusion: This multicenter retrospective observational cohort study demonstrated that surgery within 24 hours was associated with reduced major hospital complications, immobility complications and ICU LOS for children and adolescents with complete traumatic SCI, though no mortality differences were observed. Surgical timing was influenced by several patient and injury factors, some of which raise questions about the equity of care delivery. We did not find evidence to suggest reduced in-hospital complications, mortality or LOS conferred by surgery performed within 12 hours compared to surgery at 12-24 hours. There is a demonstrated and unmet need to determine the influence of surgical timing on long-term functional outcomes for children and adolescents with complete SCI through future prospective research.

ID: 1993

A330: Hospital outcomes in incomplete cervical spinal cord injury without instability

Vishwathsen Karthikeyan ¹ , Armaan Malhotra ¹ , Husain Shakil ¹ , Christopher Lozano ¹ , Ahmad Essa ² , Jefferson Wilson ¹ , Christopher Witiw ¹ , Jetan Badhiwala ³

¹ Li Ka Shing Knowledge Institute, St. Michael's Hospital, Division of Neurosurgery, Department of Surgery, Institute of Health Policy Management and Evaluation, Toronto, Canada,

² Li Ka Shing Knowledge Institute, St. Michael's Hospital, Division of Neurosurgery, Department of Surgery, Toronto, Canada,

³ Sunnybrook Research Institute, Division of Neurosurgery, Department of Surgery, Toronto, Canada

Introduction: The epidemiology of traumatic spinal cord injury (SCI) is changing, with an increasing proportion of older patients presenting with cervical incomplete cord injuries, such as Central Cord Syndrome (CCS). CCS is a heterogeneous entity involving diverse injury etiologies, kinetic forces, and biomechanical properties. CCS encompasses those with and without spinal instability. It has been hypothesized that classifying cervical spinal cord injury without instability (SCIWI) could capture a more homogeneous injury pattern with similar clinical outcomes. This study aims to compare the demographics, injury characteristics, and in-hospital outcomes of SCIWI patients to other incomplete cervical SCI subtypes. Material and Methods: We conducted a multicenter observational study using data from trauma centers participating in the American College of Surgeons Trauma Quality Improvement Program (ACS TQIP) between 2010 and 2020. Patients over 16 years old with cervical spinal cord injuries were included. Abbreviated injury scale (AIS) codes were used to identify patients with cervical fractures. The cohort was divided into two groups: those with spinal column injury (fracture or dislocation) and those without instability (SCIWI). Univariate comparisons were made using t-tests for continuous variables and Chi-square tests for categorical variables. Results: There were 26,677 incomplete cervical SCI patients identified of which 11,628 had cervical fractures. A total of 1,886 (16.2%) patients with fractures experienced hospital complications, compared to 658 (8.6%) without fractures (OR 0.49, 95% CI: 0.44-0.54, p < 0.01). Immobility-related complications were more frequent in the fracture group (8.8%) than in the non-fracture group (4.8%) (OR 0.52, 95% CI: 0.46-0.59, p < 0.01). Surgical site infections occurred in 1.1% of patients with fractures and 0.5% in the non-fracture group (OR 0.47, 95% CI: 0.30-0.74, p < 0.01). Patients with fractures had a longer ICU stay (9.4 ± 9.9 vs. 6.7 ± 7.0 days, p < 0.01), more days on mechanical ventilation (10.7 ± 12.3 vs. 8.3 ± 9.8 days, p < 0.01), and a longer overall hospital stay (14.8 ± 15.1 vs. 11.1 ± 11.5 days, p < 0.01). Conclusion: This study highlights the increased morbidity associated with cervical incomplete spinal cord injuries with fractures compared to those without fractures. Patients with fractures experience more complications, including immobility-related issues, surgical site infections, and longer ICU stays, mechanical ventilation, and hospital stays. These findings suggest that SCIWI represents a distinct clinical entity with implications for patient management and rehabilitation strategies. Further research is necessary to explore long-term outcomes and refine the classification of cervical spinal cord injuries to optimize clinical care.

ID: 1535

A331: Acute traumatic cervical spinal cord injury in a defined Norwegian population: epidemiology and management

Hege Linnerud ¹ , Marianne Efskind Harr ¹ , Mona Strøm ² , Tor Brommeland ¹ , Mads Aarhus ¹ , Eirik Helseth ¹

¹ Oslo University Hospital, Oslo, Norway,

² Sunnaas Rehabilitation Hospital, Nesodden, Norway

Introduction: Traumatic cervical spinal cord injury (cSCI) is a serious condition that requires a multidisciplinary treatment approach. Recommendations for patients with cSCI are; care at a neurotrauma centre (NTC), surgical decompression and stabilization within 24 h after injury, and access to specialized rehabilitation. Contemporary population-based studies of cSCI are important for ensuring the quality and planning of health care approaches for these patients. The aims of the study were to establish the epidemiology of cSCI from a defined general population, and to estimate our institutional compliance with the general accepted treatment recommendations. Material and Methods: Southeast Norway has a population of 3.1 million people and one NTC, which provides acute care management for all cSCI patients in this region. This is a population-based cohort study of patients diagnosed with cSCI in Southeast Norway between 2015 and 2022. The main outcome variables were population-based incidence, age and gender distribution, trauma mechanism, severity of SCI (AIS grade), rate of admittance NCT, rate and timing of surgical fixation/stabilization, rate of transfer to specialized rehabilitation, and 90-day mortality. Results: We identified 387 consecutive cases of acute traumatic cSCI from 2015 to 2022 in the cohort of Southeast Norway. The population incidence was estimated at 1.6 per 100,000. The median patient age was 64.3 years, and male predominance of 74.7%. Falls accounted for the majority (65.1%) of cSCI cases, with traffic-related accidents involving bicycles (12.4%), four-wheeled motor vehicles (5.4%), and two-wheeled motor vehicles (3.4%). The majority of cases presented with sensorimotor incomplete injury, classified as AIS grade D (47%), C (23.8%), or B (12.4%), while 16.8% were sensorimotor complete (grade A). Ninety-six percent (370/387) of all patients diagnosed with cSCI in Southeast Norway during the study period were referred to the NTC for acute management. Surgical intervention was performed in 75% of cases. In the surgically treated group, the median time from injury to acute surgery was 27.8 h, and 47% had surgery within 24 h. Surgery was performed at equal rates regardless of age. Of the patients admitted to NTC, 54% of patients received inpatient specialized rehabilitation, of whom 70% were transferred directly from the NTC to the rehabilitation centre. Advanced age, especially among octogenarians, was significantly linked to a lack of specialized rehabilitation. The 90-day mortality rate was 13%, while for octogenarians, the 90-day mortality rate was 32%. Conclusion: Acute treatment of patients with cSCI is complex. Knowledge of incidence and patient characteristics is important in planning of specialized health-care resources. In Southeast Norway, 96% of cSCI patients are transferred to the NTC for acute treatment. Surgery was performed in 75 % of the patients and barely a half were operated within the recommended 24 hours. In some patients there might be strong reasons for both to restrain from and/or delay surgical treatment, but any restrain or delay should be carefully reviewed, in order to secure an optimal treatment chain. The fraction of patients receiving specialized treatment is also rather low (54%), especially in the elderly, and studies to separate if this is based on medical considerations or limited resources are warranted.

ID: 2829

A332: Short-term outcome of subaxial cervical spine injuries management

Mahmoud Fouad Ibrahim ^1,2 , Peter Gayed ² , Essam Mohammed El-Morshidy ^1,2 , Mohammad El-Sharkawi ^1,2

¹ Faculty of Medicine, Assiut University, Assiut, Egypt,

² Orthopaedic & Trauma Surgery Department, Assiut University Hospital, Assiut, Egypt

Introduction: Cervical spine injuries account for 3% of blunt force trauma patients, with sub-axial cervical spine being the most prevalent site of damage. Fifty percent of injuries occur between C5 and C7. It leads to high morbidity having a detrimental impact on the patients and their families as well as a higher rate of disability and functional loss in the society. The aim of this prospective series was to report on the incidence and mechanism of injury of subaxial cervical spine in our locality and to look into the short-term clinical and functional consequences of managing these injuries in our institution. Material and Methods: All patients with sub-axial cervical spine injury presenting to our institution between January 2022 and December 2023 were included. Age, mode of trauma, anatomical level of injury, neurological deficit at time of diagnosis and type of management were recorded. The outcome measurements comprised a self-reported measure (Neck Disability Index) and neurological status according to the American Spinal Injury Association (ASIA) Impairment Scale (AIS). Perioperative and delayed complications were recorded. Patients were followed up at 2 weeks, 6 weeks, and 3 and 6 months. Results: The study involved 190 patients, whose age ranged from 10 to 85 years, with a mean age of 44 years. Male predominance (87.4%) was observed. The major mode of the trauma was road traffic accidents (51.1%) followed by a fall from height (24.2%). Sixteen patients (8.4%) had associated upper cervical injury (4 patients) or thoraco-lumbar injury (12 patients). Type C was the most common injury encountered (75 patients). On admission, 53 patients (27.9%) were grade A, 19 patients (10.0%) were B, while 62 patients (32.6%) were C, 21 patients (11.1%) were D and 35 patients (18.4%) were grade E. Twenty patients (10.5%) were managed conservatively, and 145 patients (76%) were managed operatively, while 25 patients (13%) died before the scheduled intervention due to respiratory failure. Anterior discectomy/corpectomy and stabilization was performed in 94 patients (64.8%). Posterior Laminectomy with posterior stabilization was performed in 41 patients (28.4%), and combined procedures in 10 patients (6.9%). Thirty patients (24.4%) improved by one or more grades in their AIS. Between two weeks and six months, there is a considerable improvement in the overall NDI values (P-value: 0.001). No patient was diagnosed with pseudoarthrosis. A very high mortality rate (35.2%) within the first 6 months was observed. Conclusion: Road traffic accident is the most common cause of sub-axial cervical spine injuries in the young people in our society leading to higher rate of morbidity and mortality. Operative management is the treatment of choice in patients with neurological deficit. Preoperative neurological state is a key predictor of postoperative neurological recovery. Most patients show good functional outcome with excellent NDI regardless the type of management. Preventive measures must be induced in order to avoid the consequences of these injuries for our society and economic resources.

Keywords: Subaxial cervical spine injuries, Neck Disability Index (NDI), American Spinal Injury Association (ASIA) Impairment Scale (AIS), Road Traffic Accident (RTA)

ID: 657

A333: Risk factors for venous thromboembolism in patients with acute cervical spine fracture

Allen Zou ¹ , Emily Adams ² , Leila Erbay ¹ , Andrew Li ¹ , Antonio Lobao ² , Daniel Chen ¹ , Mohamed Yousef ² , Robert Shepard ¹ , Raj Gala ² , Michael Stauff ²

¹ UMass Chan Medical School, Worcester, United States,

² UMass Memorial Medical Center, Department of Orthopedics and Physical Rehabilitation, Worcester, United States

Introduction: Patients who sustain cervical spine fractures (CSFXs) are at risk for venous thromboembolism (VTE). We hypothesize that certain risk factors allow for better prediction of patients who are at a higher risk of VTE in the setting of CSFXs. Material and Methods: Medical records of 671 adult patients who presented with traumatic CSFXs to a single trauma center from 2017-2023 were retrospectively reviewed. Demographics, comorbidities, injury details, and VTE within 30 days of CSFX were collected. Patients were grouped by no VTE, deep vein thrombosis (DVT), and pulmonary embolism (PE). CSFXs were sorted by mechanism of injury (MOI) and characterized by AO Upper Cervical and Subaxial Classifications. Results: Patients had an average age of 64.1 years (SD = 19.6) and BMI of 27.6 (SD = 6.9); 267 (40%) patients were female. There were 34 DVTs (5.1%) and 13 PEs (1.9%) in the cohort. There was a significant difference in length of stay between DVT and no VTE (33.4, 9.1, p < 0.001) and between PE and no VTE (65.3, 9.1, p < 0.001). Higher odds of death were seen in DVT (OR= 108.3; 95% CI, 12.25-956.99) and PE (OR= 392.5; 95% CI, 41.06-3751.91) compared to no VTE. There was no significant difference in the pre-injury use of antiplatelets or anticoagulants between VTE groups and no VTE. There was no significant difference in smoking status between VTE groups and no VTE. Patients with DVT were less likely to have a history of alcohol use compared to no VTE (38.2%, 56.1%, p = 0.041); there was no difference in alcohol use between PE and no VTE. Patients with DVT or PE had a higher average injury severity score (ISS) than no VTE (21.47, 12.85, p < 0.001), (24.77, 12.85, p = 0.006), respectively. The average Glasgow Coma Score (GCS) was lower in the DVT group than no VTE (11.97, 14.17, p < 0.001). Those who developed DVT had more severe CSFXs (AO B or C) than no VTE (AO B: 32.4%, 16.5%, p = 0.018; AO C: 32.4%, 18.6%, p = 0.048). Compared to no VTE, DVT and PE groups had higher rates of concomitant injuries, such as SCI (p < 0.001; p = 0.036), severe SCI (ASIA A) (p < 0.001; p < 0.001), abdominal visceral injuries (p = 0.028; p = 0.025), thoracic visceral injuries (p = 0.003; p = 0.010), spine surgery (p < 0.001; p = 0.012), and non-spine surgery (p < 0.001; p < 0.001); retroperitoneal injuries were more common in DVT than no VTE (p = 0.002). Conclusion: CSFX patients with lengthy admissions, poor ISS and GCS scores, and severe CSFXs (AO B or C) are at higher risk to develop VTE. Body cavity visceral injuries, SCI, severe SCI (ASIA A), and surgical treatment are more prevalent in CSFX patients with VTE. For patients with CSFX and these additional risk factors for VTE, special consideration should be given for multimodal VTE prophylaxis, including mechanical and chemical VTE prophylaxis and consideration for inferior vena cava filters.

OP38: Adult Deformity-Thoracolumbar 2

ID: 666

A334: Tethers and vertebroplasty as preventive measures for proximal junctional kyphosis in adult spinal deformity: a meta-analysis

Esteban Quiceno Restrepo ¹ , Mohamed Soliman ¹ , Asham Khan ¹ , Benard Okai ² , Isabelle Stockman ² , Shashwat Shah ² , Hendrick Francois ² , Jacob Greisman ¹ , Joseph St. Onge ² , Deanna Chan 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: PJK is a radiological finding that may occur in up to 40% of cases following surgical intervention for ASD. It can progress to clinical symptoms necessitating reoperation. Recently numerous studies have explored diverse adjunctive instrumentation methods aimed at preventing proximal junctional pathology. The objective of this study was to determine the protective effect of adjunctive methods for PJK. Material and Methods: Adhering to PRISMA guidelines, we systematically searched the PubMed/Medline, EMBASE, and Cochrane databases for full-text articles in the English-language literature. Our inclusion criteria encompassed studies comparing PJK, proximal junctional failure, and reoperation rates among patients undergoing ASD who were treated with and without tethers, as well as those treated with and without VPL. We calculated Odds ratios (ORs) to evaluate disparities in PJK occurrence and reoperation rates, and a random effect model was used. Results: Eight studies compared the use of tethers, involving a total of 1430 patients. The tether group demonstrated a lower OR for radiographic proximal junctional kyphosis (PJK) and reoperation, with OR = 0.46 (95%CI 0.22, 0.93, p = 0.02) and OR = 0.46 (95%CI 0.22, 0.93, p = 0.03), respectively. There was no significant increase in perioperative complications or surgical time associated with the use of tethers. Five studies comparing the use of vertebroplasty in the upper instrumented vertebra (UIV)+1 and UIV+2 were included in the analysis, comprising a total of 693 patients. VPL was found to be protective against reoperation due to proximal junctional pathology, with OR = 0.25(95% CI 0.12,0.49, p < 0.01). However, there was no significant difference in the development of radiographic PJK between groups that used VPL and those that did not, with OR = 0.91 (95%CI0.23,3.54, p = 0.89). Conclusion: The utilization of tethers prevents the development of radiographic PJK and reduces the need for reoperation. Similarly, vertebroplasty serves as a preventive measure against reoperation due to proximal junctional pathologies. These techniques do not entail an increase in additional complications. However, further studies are necessary to ascertain the optimal combination of these techniques for enhanced efficacy.

ID: 395

A335: The predictive value of multifidus degeneration in osteoporotic vetebral compression fracture patients with kyphosis deformity

Junyu Li ¹ , Zimo Wang ¹ , Gengyu Han ¹ , Zhuo Ran Sun ¹ , Yongqiang Wang ¹ , Miao Yu ¹ , Weishi Li ¹ , Lin Zeng ¹ , Yan Zeng ¹

¹ Peking University Third Hospital of China, Beijing, China

Introduction: Osteoporotic vertebral compression fracture (OVCF) causes pain, kyphosis and neurological damage, which significantly affect patients’ quality of life. Patients with OVCF are often elderly and have severe osteoporosis, which makes preoperative symptom more serious, postoperative recovery worse and the incidence of postoperative complications high. The paraspinal muscles have been well studied in adult spinal deformities, but there is no conclusive evidence that their findings can be applied to OVCF. The purpose of this study was to evaluate the associations between multifidus (MF) parameters including fat infiltration (FI), relative functional sectional area (rFCSA), relative gross cross-sectional area (rGCSA) and the sagittal parameters, symptom score, and postoperative complications. Material and Methods: The study included 108 OVCF patients with kyphosis deformity who underwent corrective surgery and were followed for two years. MRI were performed preoperatively to evaluate the paraspinal muscle morphology, including MF fat infiltration (MFFI), relative functional cross-sectional area (MFrFCSA), and MF relative gross cross-sectional area (MFrGCSA). VAS, ODI, JOA, and SRS-22 were conducted preoperatively. Preoperative, postoperative and last-follow up spine sagittal parameters were recorded, as well as sagittal balance, loss of correction results and improvement and deterioration of sagittal parameters. The occurrence of postoperative mechanical complications, including adjacent segment disease, screw loosening, proximal junctional kyphosis, and distal junctional problem were recorded. We analyzed the relationship between MF degeneration and the above parameters. Results: Strong correlation was observed in VAS and MFFI (rr = 0.597, p = 0.000), MF rFCSA(RR = -0.520, p = 0.001) and MF rGCSA (RR = -0.461, p = 0.005), as well as ODI and MFrFCSA (RR = -0.336, p = 0.042). Preoperatively, strong correlations were observed between MF rFCSA and LL (rr = -0.320, p = 0.010), TLK (RR = -0.271, p = 0.026), TK (rr = -0.251, p = 0.048). MF rGCSA and LL (rr = -0.259, p = 0.039), TLK (rr = -0.247, p = 0.043), TK (rr = -0.273, p = 0.030), GK (rr = -0.381, p = 0.002) were also strongly correlated. Our study showed strong correlations between MF FI and TLK loss (rr = 0.406, p = 0.003), TK loss (rr = 0.332, p = 0.045); MF rGCSA and SVA loss (rr = -0.367, p = 0.050), TPA loss (rr = -0.404, p = 0.030); MF rGCSA and TPA loss (rr = -0.401, p = 0.031), MF FI and GK loss (rr = 0.397, p = 0.027). MF FI was significantly higher in the complication-presence group (p = 0.045). Conclusion: Multifidus degeneration is significantly associated with QoL, sagittal parameters and mechanical complications in OVCF patients with kyphosis deformity. The pathological changes of paravertebral muscles should be included in the surgical strategy and postoperative paravertebral muscle rehabilitation should be adopted to improve the clinical outcomes of OVCF patients.

ID: 2459

A336: Minimally invasive vs open surgery in adult spinal deformity, evaluating post operative pain

Puya Alikhani ¹ , Cesar Carballo ²

¹ University of South Florida, Neurosurgery, Tampa,

² University of South Florida, Neurosurgery, Tampa, United States

Introduction: The ongoing opioid crisis has highlighted the importance of minimizing opioid prescriptions following major surgeries. Spinal surgery, particularly in adult spinal deformity (ASD), presents a significant challenge in postoperative pain management due to the complexity of the procedures and the high prevalence of preoperative pain. Minimally invasive spine surgery (MIS) has been increasingly adopted as a means of reducing recovery time, minimizing postoperative complications, and potentially decreasing opioid dependence. However, questions remain regarding its efficacy in pain management, especially when compared to traditional open spine surgery, which may offer superior deformity correction through improved spinopelvic alignment. This study aims to compare postoperative pain and opioid use between MIS and open surgery in ASD patients, with a focus on the relationship between surgical technique and spinopelvic alignment correction. Methods: We retrospectively analyzed adult patients undergoing ASD surgery at our tertiary care center between 2016 and 2023. The cohort included MIS (n = 36) and open surgery (n = 194) cases. ASD was defined as any spinal construct extending from L2 to the pelvis with posterior instrumented fixation or greater. Pain outcomes were measured using the visual analogue scale (VAS) for both back and leg pain, with higher VAS scores indicating greater pain. Postoperative opioid prescription data were collected, and chronic opioid use was defined as use persisting for ≥ 3 months postoperatively. Patients with incomplete data on opioid use or pain scores were excluded. Statistical analysis was performed using SPSS, with significance set at p < 0.05. Results: Surgical technique was significantly associated with differences in postoperative pain. At 3 months, patients who underwent open surgery reported lower back VAS (1.59) and leg VAS (0.88) scores compared to MIS patients, who had back VAS of 2.72 and leg VAS of 1.89 (p < 0.001). However, there was no significant difference in postoperative opioid use (p = 0.07) or chronic opioid use (p = 0.70) between the two groups. These results suggest that the superior correction of spinopelvic alignment achieved with open surgery likely contributes to better postoperative pain control, particularly in the medium-term recovery phase. The lack of significant differences in opioid use may be attributed to standardized pain management protocols across both surgical approaches. Conclusions: Open surgery for ASD provides better postoperative pain relief compared to MIS, likely due to superior spinopelvic alignment correction. Despite MIS's advantages in minimizing tissue damage, its role in ASD may be limited by its capacity for deformity correction, which remains a key factor in postoperative outcomes. Future studies should investigate strategies to enhance deformity correction in MIS while maintaining its minimally invasive benefits.

ID: 1064

A337: A novel technique for correction of thoracolumbar kyphotic deformity: the wedge vertebra forward-shifting technique and preliminary experience

Jianfeng Guo ¹ , Feng Li ¹

¹ Tongji Hospital Attached to Tongji Medical College Huazhong University of Science and Technology (HUST), Department of Orthopaedic Surgery, Wuhan, China

Introduction: Thoracolumbar kyphotic deformity is a clinical challenging problem result in pain or neurological dysfunction. The common etiology includes congenital and post-traumatic. Traditionally, thus deformity is corrected by technically demanding osteotomy procedure, such as Schwab Grade Ⅲ or Ⅳ osteotomy, with significant surgical trauma and risk of major complications. Here, we proposed a novel technique- wedge vertebra forward-shifting technique- for correction of thoracolumbar kyphotic deformity in 2014. In this study, we introduce this novel technique, its effectiveness and safety for the correction of thoracolumbar kyphotic deformity through case series. Material and Methods: Twenty-two patients with thoracolumbar kyphotic deformity corrected by wedge vertebra forward-shifting technique from 2014 to 2022 in our department were included in this study. In this novel technique, pedicle screws were inserted first in the upper and lower two vertebras, also the wedge vertebra with higher screw tail for vertebra forward shifting. Then proximal and distal intervertebral space of the wedge vertebra was released adequately through trans-articular approach like routine TLIF procedure after laminectomy. Finally, the wedge vertebra was pushed and shifted forward when tightening pre-bent rods, which simultaneously achieve neural decompression and kyphotic correction due to the higher screw tail and adequately released wedge vertebra. The ODI and JOA scores were used to evaluate clinical outcomes. The preoperative and postoperative sagittal parameters were compared. The operation time, intraoperative blood loss, postoperative hospital stays, and perioperative complications were also recorded. Results: 22 patients included 15 males and 7 females, with a mean age of 39.87 ± 17.18 years (15-68). The mean follow-up duration was 32.13 ± 6.52 months (24-48). The mean operative time of 254.00 ± 43.55 min (200-360), and mean blood loss of 740.00 ± 258.58 ml (400-1200). The mean postoperative hospital stay was 8.60 ± 2.38 d (6-14). Considering etiology, congenital kyphosis was diagnosed in 8 cases while posttraumatic kyphosis in 14 cases. All patients experienced varying degrees of relief in their pain or neurological dysfunction. The preoperative ODI and JOA scores were 51.5 ± 25.1 and 17.1 ± 7.4 respectively, 20.7 ± 9.4 and 24.4 ± 2.1 respectively at last follow-up, with statistically significance (p < 0.001). The mean local kyphotic angle was 45.8 ± 5.3° preoperatively, which significantly decreased to 6.8 ± 2.8° at last follow-up with a corrective rate of 85.2%. The lumbar lordosis increased from 37.4 ± 14. 2° preoperatively to 43.4 ± 13.9° at the follow-up (p = 0.115) with ideal match to the pelvic incidence of 43.8 ± 8.1°, and the thoracic kyphosis angle significantly increased from 4.4 ± 8.1° preoperatively to 13.2 ± 6.9° at last follow-up (p = 0.031). The SVA decreased from 20.2 ± 25.2 mm preoperative to 14.0 ± 12.5 mm postoperative, although without significant difference (p = 0.644). Complications included lower limb numbness in 2 cases, cerebrospinal fluid leakage in 2 cases, and pulmonary infection in 1 case. No patient suffered neurological deterioration. At last follow-up, internal fixation failure or nonunion was not detected. Conclusion: The wedge vertebra forward-shifting technique can be a new alternative strategy for treatment of thoracolumbar kyphotic deformity, which can safely and effectively correct thoracolumbar kyphotic deformity and gain neurological decompression. In our experience, this novel technique shows outstanding advantages in simplifying surgical procedure, reducing risk and providing biomechanical stability.

ID: 1205

A338: Reliability of DEXA based T-scores of lumbar spine, hip and femur in correlation to CT-based 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: Dual-energy X-ray absorptiometry (DEXA) and the resulting T-score are currently still considered the gold standard for bone density measurement and diagnosis of osteoporosis. In this study, we investigated the relationship of DEXA-based T-scores of the lumbar spine (LS), hip and femur in comparison to CT Hounsfield Units (HU) in patients with manifest osteoporosis. Methods: From 2019 to 2024, we analysed 350 patients with osteoporotic fractures of the spine. All patients underwent CT imaging of the lumbar spine. 170 patients were examined via DEXA scan (n = 170 with T-score of the lumbar spine, n =1 23 with T-score of the hip, n = 113 with T-score of the femur). DEXA and CT scans were filtered out of the patient data and only patients who had undergone both examinations were included. The DEXA scan was assessed using the T-scores of the lumbar spine, hip and femur. The HU was examined axially in each of three non-fractured vertebral bodies of the lumbar spine. For each vertebral body, an ROI (region of interest) was measured below the top plate, in the centre plate and above the base plate in the cancellous bone. Descriptive statistics and the chi-square test were used to analyse the data. Results: Complete DEXA and CT scans were available for 113 patients. The average age was 80 years, 68% of the patients were female, 22% were male. Most fractures were in the thoracolumbar junction (19%). A low HU score was found in 165 patients (97%), with a T-score in the osteoporotic range in 33% of DEXA lumbar spine scans, 26.8% of DEXA femur scans and 24.1% of DEXA hip scans. A statistically significant correlation was found between HU and DEXA T-score of the spine (11.6 (2, n = 113), p = 0.003) and DEXA T-score of the hip (10.3 (2, n = 113), p = 0.006. No significant correlation was found between the DEXA-T score of the thigh and the HU. In addition, no other significant differences were found with regard to demographics, age, number of fractures and fracture location. Conclusion: Even though the DEXA scan is still the gold standard, HU appears to be better suited to detecting manifest osteoporosis. DEXA was only able to reliably detect osteoporosis in patients with HU values below 50. In comparison, the T-scores of the lumbar spine and hip appear to be more suitable for detecting osteoporosis than the T-score of the femur. However, the reliability of the T-scores for the lumbar spine is also low compared to the reliability of the CT-HU of the lumbar spine and is probably unsuitable for detecting manifest osteoporosis.

ID: 2763

A339: Age adjusted alignment goals inadequately represent asymptomatic adults and are prone to undercorrection

Sarthak Mohanty ¹ , Justin Reyes ¹ , Fthimnir Hassan ¹ , Jean Charles Le Huec ² , Stephane Bourret ² , Kazuhiro Hasegawa ³ , Wong Hee Kit ⁴ , Gabriel Liu ⁴ , Dennis Hey Hwee Weng ⁴ , Michael Kelly ⁵ , Zeeshan Sardar ¹ , Lawrence Lenke ¹

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

² Bordeaux North Aquitaine Polyclinic, Bordeaux, France,

³ Niigata Spine Surgery Center, Niigata City, Japan,

⁴ National University Hospital (Singapore), Singapore, Singapore,

⁵ Rady Children's Hospital, San Diego, United States

Introduction: Recent literature emphasizes age-adjusted alignment objectives in deformity correction, advocating for less aggressive adjustments in older patients. However, applicability of these age-adjusted alignment formulas remains unverified in asymptomatic adults. Methods: 468 asymptomatic adult volunteers with biplanar spinal imaging were included in this multi-ethnic, multi-center cohort. The primary endpoint, mean absolute error (MAE), quantified the absolute discrepancy between observed and age-adjusted targets for Pelvic Incidence-Lumbar Lordosis (PI-LL) and T1 Pelvic Angle (T1PA). These targets were derived as follows: for PI-LL, [(Age-55)/2 +3]; for T1PA, [(Age-55)/2 +16]. Univariate and multivariable logistic regressions assessed the relationship between the actual-to-target alignment deviation and demographic/radiographic factors. The multivariable model adjusted for age, BMI, sex, and pelvic incidence (PI) and incorporated two-way interactions among these variables. Data are shown as [β Estimate (Std Error, P Value)]. Results: The MAE for PI-LL was 9.41°. Older age groups exhibited greater deviations: 55-65 years [4.11(1.1, 0.0002)], 65-75 years [5.9 (1.42, < 0.0001)], and > 75 years [5.71 (2.28, 0.0124)]. A significant correlation between PI and MAE was observed, with higher errors in PI ranges 60-70[ 6.3 (1.2, < 0.0001)] and > 70 [5.29 (1.47, 0.0003)]. Multivariable analysis identified increased age [0.75 (0.2, 0.0002)] and PI [0.42 (0.19, 0.0323)] as independent predictors of larger discrepancies, alongside a significant age x PI interaction [-0.01 (0.003, 0.0012)]. The greatest absolute error ( > 13°) was in participants > 55 years with PI > 60°. For T1PA, the MAE was 6.77°, with similar predictors to PI-LL in both univariate and multivariable models. In the latter, older age [0.86 (0.14, < 0.0001)] and higher PI [0.46 (0.13, 0.0005)], with a significant age x PI interaction [-0.01 (0.002, < 0.0001)], significantly influenced the error magnitude. Conclusions: Age-adjusted alignment formulas do not accurately represent asymptomatic adults. Age-adjusted targets, premised on assumed functional decline in symptomatic adults, risk under correction in older patients needing reconstructive surgery.

ID: 393

A340: Selection of proximal fusion level in chronic osteoporotic vertebral compression fracture with spinal kyphosis: 4 the importance of Hounsfield unit

Junyu Li ¹ , Yiqiao Zhang Zhang ¹ , Ben Wang ¹ , Baitao Liu ¹ , Xueshi Tian Tian ¹ , Zhuo Ran Sun ¹ , Yongqiang Wang ¹ , Miao Yu ¹ , Yan Zeng ¹ , Weishi Li 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. At least 20% people aged over 50 years had one vertebral fractures. Patients of chronic OVCF (duration of symptoms ≥ 6 weeks) is usually accompanied by spinal kyphosis and a poor quality of life(QoL), but due to advanced age, osteoporosis and paraspinal muscle atrophy, chronic OVCF surgery have a high complication rate and severe cases could lead to revision surgery and increase the cost of patients. Meanwhile, the deformity correction strategy of OVCF has been a concern and reaches no consensus, especially for selection of fusion level, which has been proved to be related to postoperative complications, such as proximal junctional kyphosis (PJK) and adjacent segment degeneration (ASD). CT value can effectively reflect bone mineral density (BMD) and the biomechanical state of the vertebra. To find the most stable vertebra as the UIV in OVCF patients, we came up with the upper maximal vertebra (UMV) and upper sagittal reverse vertebra (USRV) by Hounsfield Unit. Material and Methods: This clinical research included 70 chronic OVCF patients (14 males and 56 females) with a mean age of 63.24 ± 7.83 years and mean follow-up of 48.13 ± 20.22 months. Whole spine CT were performed for each patient. The patients were divided into groups according to whether their UIV was below the UMV or USRV. The incidence of ASD and PJK was evaluated in each subgroup. Results: The average HU value of all patients was 80.88 ± 39.84. All sagittal parameters improved significantly after operation and at follow-up. For UMV, the UIV of 31chronic OVCF patients was located on or above the UMV, while that of 39 patients was not. There was a significant difference in the rates of ASD (p = 0.003) and PJK (p = 0.010) between the 2 groups. 55 patients (78.57%) were identified to have USRV. The UIV of 26 patients was located on or above the USRV while that of 29 patients was not. There was a significant difference in the rate of ASD between the two groups (p = 0.010). Conclusion: HU values should be considered in the selection of UIV. Locating UIV on UMV might decrease the incidence of PJK and ASD, and taking USRV into the fusion level might reduce the occurrence of ASD.

ID: 606

A341: A new classification of shoulder imbalance in degenerative lumbar scoliosis: a retrospective cohort study

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

¹ Peking University Third Hospital of China, Beijing, China

Introduction: Degenerative lumbar scoliosis (DLS) is a common spinal condition in the elderly, with an incidence ranging from 2% to 68%. Shoulder imbalance (SI) is crucial in assessing the outcomes of orthopedic surgery, but there is a lack of systematic studies on the radiographic characteristics of DLS patients with SI, both before and after surgery. The study identified two types of SI in DLS patients based on clavicle orientation on the higher side. Each subtype has distinct clinical traits and requires a different surgical approach. The study's goal was to propose a new classification of preoperative SI in DLS patients and explore how this classification can guide scoliosis corrective surgery. Material and Methods: Patients with shoulder imbalance (SI) (CA ≥ 3°) were divided into type I and type II groups. The higher clavicle was congruent with the direction of the C7 plumb line (C7PL) offset in type I, whereas in type II, the higher clavicle was opposite to the direction of the C7PL offset. A comparative analysis was performed between the preoperative and postoperative radiological parameters of various patient types. Results: Of all the 297 patients with DLS, 216 are with balanced shoulders and 81 had SI, with the latter divided into type I and type II patients, of 33 and 48 patients respectively. The preoperative scores of JOA and Owestry of the imbalanced group were worse than those of the balanced group (p = 0.048; p = 0.044). Type I patients had a lower postoperative CVA than that of type II (p = 0.025) and balanced group (p = 0.004), and a lower SOA at the last follow-up than the balanced group (p = 0.015); while type II patients had a higher preoperative SOA (p = 0.033) and postoperative AVT(p = 0.001) than the balanced group, and a higher postoperative. In both types of SB, the male to female(M/F) ratio in patients who had a persistent postoperative SI (postoperative-CA-persistent group) was significantly higher than that in patients who recovered from SI postoperatively (postoperative-CA-recovered group) (type I, p = 0; type II, p = 0). Compared to patients who had a persistent postoperative SI, type I patients who recovered from SI had a lower preoperative and postoperative Cobb angle (p = 0.01; p = 0.012), while type II recovered patients showed a higher postoperative Sacral obliquity angle (SOA) (p = 0.015). Further correlation analysis revealed that the postoperative CA in type I patients is significantly correlated with preoperative Cobb (p = 0.014); while in type II patients, the postoperative CA is significantly correlated with preoperative CVA (p = 0.041) and postoperative SOA (p = 0.001). Conclusion: SI patients can be classified into Type I and Type II. Type I patients have flexible shoulders that help reduce body slant by tilting in the opposite direction, avoiding pelvic compensation during recovery. Type II patients have stiff shoulders, requiring compensatory sacral tilt, which can worsen coronal deformity. Different surgical strategies should be applied: for Type I, improving the Cobb angle during surgery is key, while intraoperative SOA residue in type II patients are necessary for achieving postoperative SB.

ID: 2767

A342: Normative alignment goals using machine learning finds the sweet spot between pseudarthrosis and proximal junctional kyphosis in adult spinal deformity

Sarthak Mohanty ¹ , Justin Reyes ¹ , Josephine Coury ¹ , Erik Lewerenz ¹ , Fthimnir Hassan ¹ , Joseph Lombardi ¹ , Ronald A. Lehman ¹ , Zeeshan Sardar ¹ , Lawrence Lenke ¹

¹ Columbia University Medical Center, New York, United States

Introduction: Traditional age-adjusted spinopelvic alignment formulas risk under-correction in ASD patients. Leveraging machine learning, this study develops surgical targets by analyzing alignment in asymptomatic volunteers. Methods: A predictive model was built for PI-LL from 468 asymptomatic adults (80% training, 20% validation) across multiple centers/ethnicities. The eXtreme Gradient Boosting algorithm utilized PI, age, & sex. To validate targets, we analyzed 458 ASD patients with 2Y follow-up. These patients were classified as under-(UC), adequately-(AC), or over-corrected (OC), based on the model’s targets ± 5°. Key outcomes were pseudarthrosis/implant breakage & PJK. Outcomes were analyzed using multivariable regression models, adjusted for significant variables identified in univariate analyses. Data shown as [UC vs AC vs OC, P (ANOVA)]. Results: Mean absolute error between observed & predicted PI-LL were 3.04° & 5.02° for training & validation groups. In the surgical ASD cohort, 149 (32.5%), 159 (32.8%), & 150 (34.7%) patients were UC, AC, & OC respectively. Differences were observed in instrumented levels (12.31 vs 12.69 vs 13.8, p = 0.0028), baseline PI-LL (30.3° vs 22.1° vs 17.8°, p < 0.0001), & T1PA (30.9° vs 26.0° vs 23.4°, p < 0.0001). Pseudarthrosis rate was 9.82% (45/548), with highest incidence in UC cohort (15.4% vs 8.18% vs 6.0%, p = 0.0161). PJK rate was 10.0% (46/458), most prevalent in OC group (19.3% vs 6.04% vs 5.03%, p < 0.0001). In an adjusted multivariable model (p < 0.0001, AUC = 0.76) found that AC (aOR: 0.45, p = 0.046), & OC (aOR: 0.41, p = 0.044) had lower odds of pseudarthrosis compared to UC patients. In an adjusted PJK model (AUC = 0.687, p < 0.0001), AC had lower odds of PJK compared to OC (OR: 0.45, p = 0.0034). Both models found the current classification supersedes baseline alignment and magnitude correction in association with pseudarthrosis & PJK. Conclusions: Machine learning-derived PI-LL targets demonstrate a critical balance in deformity correction. Deviation from these tailored benchmarks increases risk of pseudarthrosis when under-corrected and PJK when over-corrected.

OP39: Degenerative Lumbar Spine Surgery 2

ID: 1480

A343: Transforaminal lumbar interbody fusionfor degenerative lumbar spine disease improves lumbar lordosisand functional outcomes

Mthunzi Ngcelwane ¹ , Tsediso Makhwela ¹ , Mawande Mandaba ²

¹ University of Pretoria, Orthopaedics, Pretoria, South Africa,

² Mercantile Hospital, Orthopaedics, Port Elizabeth, South Africa

Introduction: Degenerative lumbar spine disease causes gradual loss of lumbar lordosis and mechanical instability. Failure to restore lumbar lordosis during operation causes a flat-back syndrome, resulting into back-pain due to loss of sagittal balance. This study is aimed at assessing the extent of restoration of lumbar lordosis and its relation to clinical outcomes in patients treated with a Transforaminal lumbar interbody cage for a single level fusion in lumbar degenerative disease. Material and Methods: This is a retrospective study of 57 patients who had a one level lumbar spine fusion for degenerative lumbar spine disease, using a TLIF cage. We calculated the change in Lumbar Lordosis (LL) and Segmental Lordosis (LS) between pre-op and post-op radiographs and assessed its correlation to Oswestry Disability Index (ODI) and visual analogue scale (VAS) score. Descriptive statistics were determined for continuous variables and frequencies and their percentages were determined for categorical variables. To test statistical significance for categorical variables, Fisher’s exact test or χ2 analysis as appropriate was used. All statistical tests were performed at a 5% level of significance. Results: The overall mean age was 60 years (SD: 8.16), majority (73.68%, n = 42) were in the age group < 65 years. The mean follow-up was 22 months. Statistically significant difference was detected for pre-operative and final follow up comparison for LL (39 ± 10.73° vs 44 ± 10.91°; p = 0.0023) and SL (15 ± 8.07° vs 21 ± 7.06°; p < .0001). This is an indication of a significant improvement of 4.7 ± 11.18° and 6.2 ± 7.40° in LL and SL, respectively. The overall patients’ back pain VAS scores correlated significantly with the final LL (r = -0.25, p = 0.007), meaning that patients with greater LL (r = -0.38, p = 0.011) and SL (r = -0.307, p = 0.043), tended to have less back pain and showed better recovery and function according to the ODI scores. Conclusion: Fusion with TLIF improves global and segmental lumbar lordosis. The functional outcomes of ODI and VAS also improve as lumbar lordosis improves.

ID: 1393

A344: Evaluating lumbar lordosis restoration and adjacent segment disease risk: a comparative study of ALIF versus TLIF in degenerative lumbar pathologies

Yi Zhang ¹ , Ved Vengsarkar ^2,3 , Jialun Chi ³ , Hanzhi (Leo) Yang ³ , Ariaz Goudarzi ³ , Eunha Oh ³ , Xudong Li ³

¹ The Second Xiangya Hospital of Central South University, Department of Spine Surgery, Changsha, China,

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

³ University of Virginia School of Medicine, Department of Orthopaedic Surgery, Charlottesville, United States

Introduction: In the context of degenerative lumbar diseases, attention to sagittal alignment has become increasingly important. Degenerative changes in the lumbar spine are typically characterized by disc space collapse and a reduction in lumbar lordosis. However, due to local compensatory mechanisms, the lumbar spine often maintains a compensatory balance. Therefore, during fusion surgery, it is crucial to identify and restore adequate lumbar lordosis to alleviate compensatory mechanisms and thus reduce the incidence of long-term adjacent segment disease (ASD). Different surgical approaches can significantly impact the restoration of lumbar lordosis. Material and Methods: This retrospective cohort study analyzed patients who underwent L4-S1 fusion surgery for degenerative lumbar disease between January 2017 and January 2022. A total of 150 patients (103 TLIF and 47 ALIF) were included. Radiographic parameters were assessed preoperatively, postoperatively, and at final follow-up. Surgical data, perioperative complications, and revision rates were also analyzed. Statistical analyses included Pearson χ2 tests, independent samples t-tests, multivariate logistic regression, and repeated measures ANOVA with post-hoc analysis. Results: The TLIF group showed significantly higher blood loss and a shorter operative time compared to the ALIF group. The TLIF group had a higher overall revision rate (25.2%) compared to the ALIF group (8.5%). Postoperative ASD rates were significantly higher in the TLIF group (15.5%) compared to the ALIF group (4.3%). Compared to the TLIF group, the ALIF group demonstrated a more significant increase in lumbar lordosis (-1.4 ± 6.6 vs 4.1 ± 6.8; p < 0.001) and L4-S1 lordosis (1.7 ± 6.4 vs 7.2 ± 5.6; p < 0.001). Additionally, the ALIF group showed a significant reduction in the L3-L4 intervertebral angle (0.2 ± 3.3 vs -2.6 ± 2.0; p < 0.001), which was associated with a decreased risk of ASD. Delta L3-L4 was identified as a risk factor for ASD, with an adjusted OR of 1.269 (95% CI: 1.031-1.562; p = 0.024). Conclusion: Effective restoration of lumbar lordosis during L4-S1 fusion surgery is associated with a lower incidence of ASD. ALIF appears to be more effective than TLIF in restoring lumbar lordosis and may reduce the risk of ASD. This study highlights the importance of sagittal alignment in managing degenerative lumbar diseases and suggests that ALIF might offer better long-term outcomes compared to TLIF.

Keywords: Lumbar lordosis, adjacent segment disease, ALIF, TLIF, sagittal alignment, spinal fusion

ID: 1725

A345: Risk factors for sacroiliac joint dysfunction and fusion following lumbar fusion: a retrospective database study

William Karakash ¹ , Ali Issani ¹ , Henry Avetisian ¹ , Marc Abdou ¹ , Bahador Athari ¹ , Ram Alluri ¹ , John Liu ² , Jeffrey C. Wang ¹

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

² Keck School of Medicine of USC, Department of Neurological Surgery, Los Angeles, CA, United States

Introduction: Lumbar interbody fusion (LIF) is a standard surgical treatment for degenerative spinal conditions. However, recurrent low back pain is common after this surgery, with sacroiliac joint dysfunction increasingly recognized as a significant factor. LIF limits the spine’s capacity for compensatory changes, redirecting force towards the sacroiliac joint. This redistribution increases both stress and movement in the sacroiliac joint. Given the extensive innervation of this joint, even slight increases in motion can result in pain. This study aims to identify risk factors for sacroiliac joint dysfunction (SIJD) or sacroiliac joint fusion (SIF) after undergoing lumbar fusion surgery. Materials and Methods: A retrospective analysis was conducted using the PearlDiver Mariner database to identify patients who underwent lumbar fusion between 2010-2022. International Classification of Disease, 9th and 10th Edition (ICD-9, ICD-10) and Current Procedural Terminology (CPT) codes were used to extract relevant diagnoses and procedures. Exclusion criteria included patients under 18 years of age, and those with malignancy, infection, or trauma. Rates of SIJD and SIF were assessed postoperatively. Patient demographics and operative characteristics were gathered to determine predictors of SIJD and SIF. Statistical analysis included student’s t-tests and chi-squared analyses for continuous and categorical data, respectively. Results: Among 620943 patients identified who underwent lumbar fusion, 114402 (18.4%) developed SIJD, and 5846 (0.9%) underwent subsequent sacroiliac fusion. Risk factors for SIJD included female sex (OR 1.58), osteoporosis (OR 1.41), obesity (OR 1.22), posterior instrumentation (OR 1.18), multi-level procedures (OR 1.15), and preoperative opioid use (OR 1.03). The risk increased with the number of fused lumbar levels, with odds ratio rising from 1.05 for two levels to 1.62 for five levels (p < 0.001 for all). Similar factors were associated with subsequent SIF, but with stronger associations. Preoperative opioid use showed the strongest association (OR 2.09), followed by multilevel procedures (OR 2.0), posterior instrumentation (OR 1.72), obesity (OR 1.54), osteoporosis (OR 1.53), and female sex (OR 1.35) (p < 0.001 for all). The number of fused lumbar levels also correlated strongly with the rate of subsequent SIF, with odds ratios increasing incrementally from two-levels (OR 1.36), three levels (1.69), four levels (2.49), to five levels (3.59) (p < 0.001 for all). Conclusion: This study reveals significant rates of sacroiliac joint dysfunction and fusion following lumbar fusion procedures, with key risk factors including female sex, osteoporosis, obesity, posterior instrumentation, multi-level procedures, and preoperative opioid use. The risk escalates with each additional fused lumbar level, supporting the theory of incremental force redistribution to the sacroiliac joint. The stronger associations observed for sacroiliac fusion suggest these factors contribute to both the development and progression of dysfunction. These findings underscore the need for careful surgical planning and patient counseling, particularly in multi-level fusions. Future research should focus on preventive strategies and optimized treatments for patients at high risk.

ID: 1351

A346: Predictors for poor outcome after lumbar discectomy in the National FinSpine Register - a review of 3339 patients

Jussi Repo ¹

¹ Tampere University Hospital, Tampere, Finland

Introduction: Lumbar discectomy for herniated disc is a common spinal procedure. Despite the surgical treatment, some patients are left with persistent pain and poor health-related quality of life. We aim to research preoperative predictive factors associated with poor outcome after lumbar discectomy. Material and Methods: National spinal surgery database (FinSpine) was searched for patients who had undergone primary discectomy for lumbar disc herniation. All patients had a minimum of 2 years follow-up. The Oswestry Disability Index (ODI) was used to categorize patients into either satisfactory (0-40) or poor outcome groups (41-100). Preoperative patient characteristics and patient-reported outcome data during the follow-up were collected and a logistic regression analysis performed. Results: In all, 3339 patients were included, of whom 2991 (90%) had minimal to moderate disability and 348 (10%) had severe disability assessed with ODI at the follow-up. Several factors were identified to associate with poor outcome after the surgery: older age (OR 1.03, 95%CI 1.02.1.03), female sex (OR 1.28, 95%CI 1.03-1.61), higher body mass index (OR 1.06, 95%CI 1.02-1.09), cardiologic comorbidity (OR 4.27, 95%CI 2.4-7.3), regular preoperative painkiller use (OR 2.2, 95%CI 1.5.3.3), and higher number of operated vertebrae (OR 2.4, 95%CI 1.6-3.6) were associated with poor outcomes. Symptoms lasting over one year was associated with worse outcomes when compared to symptoms for 3-12 months (OR 0.42, 95%CI 0.29-0.60), 6-12 weeks (OR 0.23, 95%CI 0.12-0.39), and those with symptoms for less than 6 weeks (OR 0.35, 95%CI 0.19-0.62). Employed individuals were associated with better outcomes when compared to those on a pension (OR 4.1, 95%CI 2.6-6.4), unemployed individuals (OR 4.4, 95%CI 2.6-7.2), and disabled individuals (OR 2.5, 95%CI 1.7.3.8). Worse preoperative quality of life scores was associated with poor outcomes after 12 months of follow-up. In the poor outcome group, ODI scores remained lower in all follow-up timepoints when compared to satisfactory outcome group. Conclusion: Several preoperative factors were associated with poor outcome after lumbar discectomy for disc herniation. These findings can be used inform the patients of potential outcomes.

ID: 1577

A347: The impact of psychological status on final outcomes in primary and revision lumbar spinal fusion surgeries

Aleksandar Vujadinovic ¹ , Amila Vujadinović ² , Jasmina Sivčević ³ , Nejra Šabanović ³ , Azra Kurtić ³

¹ ASA General Hospital, Orthopaedic, Sarajevo, Bosnia and Herzegovina

² Public Health Center “Dr. Mustafa Šehović”, Family Medicine Dept., Tuzla, Bosnia and Herzegovina,

³ Medical Faculty University of Tuzla, Tuzla, Bosnia and Herzegovina

Introduction: Lumbar spine fusion is today one of the most often performed surgical procedures with an average success rate of 70-80%. The need for revision surgeries after lumbar fusion causes disappointment for patients and the surgeons. The incidence of revision varies according to different studies, but most studies report data on 11% to 30% after fusion, in some studies up to 40%. Among others factors, psychological status is perhaps one of the most important factors that influence the final result and patient satisfaction in primary and revision lumbar spine surgeries. In this study, the authors analyzed the influence of patient's preoperative depression level on pain and functional improvement in primary and revision lumbar spinal surgeries. Material and Methods: In this prospective randomized study we have analyzed 64 patients (38 females and 26 males) average age of 53 year (31-73) in which primary and revision spine surgery performed at tertiary level center between 2016 - 2021. The patients were divided in Group 1 (patients in which index lumbar fusion surgery performed, 60.9%), Group 2 (patients with one revision, 17.2%) and Group 3 (those with multiple revision spine surgeries, 21.9%). In all patients we preoperatively analyzed psychological and functional status using Zung depression scale, VAS and Oswestry disability index (ODI) questionnaires they filled out the day before surgery as well as 2 years after the surgery. The findings statisticaly calculated with level of significance of p < 0.05. Results: The average score on Zung depression scale was 49.97% what was in range of normal to mild depression, 1,5 % patients were severely depressed and rest of patients were mildly to moderately depressed (48.53%). ODI score before surgery was 36,59 on average which relay to completely disabled individuals, while after index or revision surgery was 12.91 (mild disability). VAS score before surgery was 84.02, and after the surgery was reduced approximately 4 times, to 22.55. With standard multiple regression statistical analysis we have found that depression feeling had significant influence on postoperative functional outcome and pain in Group 1 (p < 0.05) and Group 3 (p < 0.05), while significant influence is related only on postoperative pain but not on functional outcome in Group 3 (p = 0.08). Conclusion: Depression generally has a very important and significant role on functional outcome and pain after lumbar spine fusion surgeries in primary and especially in multiple revision surgeries. This is something that have to be discussed with patient before any lumbar spine fusion surgeries.

ID: 1635

A348: A single expandable cage via a hybrid posterior-transforaminal approach with rhBMP-2 or allograft provides high fusion rates with low risk of subsidence

Charlie Faulks ¹ , Kaiwen Cabbabe ¹ , Dean Biddau ¹ , Nigel Munday ¹ , Gregory Malham ¹

¹ Epworth HealthCare, Melbourne, Australia

Introduction: Due to the ongoing debate surrounding the clinical impact of surgical technique; cage type (expandable versus static), cage shape (straight versus banana), or technique (posterior lumbar interbody fusion (PLIF) versus transforaminal lumbar interbody fusion (TLIF)), the aim of this study was to evaluate the mid-term clinical and radiographic outcomes of patients who underwent a hybrid P-TLIF with a single straight expandable titanium cage using recombinant human bone morphogenetic protein-2 (rhBMP-2) or demineralised bone allograft (DBA) bone substitute. Methods: A retrospective analysis of data from consecutive patients who underwent a hybrid P-TLIF by a senior spine surgeon between August 2017 and May 2022. A single straight expandable interbody cage was inserted obliquely after laminectomy and bilateral facetectomies. Cages were packed with either rhBMP-2 or DBA. Consecutive patients received rhBMP-2 prior to withdrawal (Australia, March 2020), and then DBA was used. Patient reported outcome measures (PROMs) included visual analogue scale (VAS) back and leg pain, Oswestry disability index (ODI) and 12-Item Short Form Survey (SF-12) measured at preoperative, postoperative 6-week, 6-month, 12-month, and 24-months. Computed tomography (CT) imaging, assessed by an independent radiologist, was conducted postoperative day-2 for instrumentation positioning then at either 6-, 12- or 24-months to assess subsidence and interbody/posterolateral fusion (Bridwell Classification). If fusion was achieved no further CTs were undertaken. Results: This cohort consisted of 81 (54.3% female) patients with a mean age of 57.3 ± 12.5 years. rhBMP-2 was used in 60 (74%) and DBA in 21 (26%) patients. Total clinical complication rate was 27.2% including 5 patients requiring reoperation. Asymptomatic radiologic subsidence rate was 7.4% and clinical subsidence rate was 1.2%. Total (interbody and posterolateral) fusion was achieved at 6-months in 34.4% and 55.8%, 12-months in 76.8% and 88.4%, and 24-months in 86.3% and 93.2% of patients. There was a non-significant difference in fusion rates at each timepoint between rhBMP-2 and DBA. Preoperative pain, disability, and function all significantly improved postoperatively. Mean VAS back/leg (7.8 ± 0.8, 7.7 ± 0.9), and ODI (35.8 ± 6.6) significantly (p < 0.0001) decreased (2.7 ± 1.8, 1.9 ± 2.3, 13.6 ± 5.8); SF-12 physical/mental (27.4 ± 3.8)/(38.1 ± 8.3) showed significant improvements (p < 0.0001) at 12-months follow-up (47.1 ± 8.8, 52.1 ± 8.7). The mean follow-up time was 20.3 ± 6.1 (12-24) months. Conclusion: A hybrid P-TLIF with a single straight titanium expandable cage permitted safe cage insertion, guided repositioning, and controlled expansion. Patients demonstrated significant improvements in pain, disability and function with low subsidence and high CT fusion rates over 24-month follow-up. The use of DBA in this cohort showed no significant difference in fusion rates across 24-months when compared to rhBMP-2.

Keywords: CT, expandable cage, posterior, transforaminal, lumbar interbody fusion

ID: 2160

A349: 3D-printed titanium: game-changer for standalone lateral lumbar interbody fusion? Analysis of risk factors for revision surgery

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

¹ Hospital for Special Surgery, New York, United States

Introduction: Lateral lumbar interbody fusion (LLIF) is a muscle-sparing technique that has raised ongoing debate about whether it should be performed as a standalone procedure or combined with posterior instrumentation. Novel 3D-printed Titanium (3DTi) cages have shown reduced subsidence and improved fusion rates compared to polyether ether ketone (PEEK) cages. However, it remains unclear whether 3DTi improves the long-term performance of standalone LLIF and reduces the risk of revision surgery. This study aims to address this gap by assessing risk factors for revision surgery after standalone LLIF, hypothesizing that 3DTi reduces revision risks. Material and Methods: A single-center retrospective cohort study was conducted on patients who underwent standalone LLIF between 2018 and 2022. Minimum follow-up was 2 years. Implanted cage type determined the two examined groups, the PEEK and the 3DTi group. Patient characteristics and surgical details were compared using Student’s t-tests, Wilcoxon rank-sum tests, chi-square tests, and Fisher's exact tests depending on parameter type and distribution. Univariate logistic regression was used to identify potential predictors of revision surgery. Variables with p < 0.2 in the group comparisons or univariate regression were included in a multivariable Poisson regression model to determine independent predictors and relative risks (RR). Secondary analyses examined differences in the rates, timing, and types of revision surgeries between the two implant types. Results: 233 patients were included for analysis (43.8% female) with median age 65 years (IQR: 56-71), BMI 28.0 (IQR: 24.7.32.1), and number of levels fused 2 (range 1-4). PEEK cages were used in 87 patients (37.3%), and 3DTi cages in 146 patients (62.7%). Patient characteristics and surgical details were similar between the groups, except for a trend towards longer follow-up in the PEEK group (3.3 years vs. 2.9 years, p = 0.065), more levels treated with 3DTi (p = 0.059), and more frequent involvement of L2/3 or above with 3DTi (52.7% vs. 37.9%; p = 0.029). Revision surgery was performed in 17.6% of patients after 26 ± 16 months. The revision rate was higher in the PEEK group (26.3%) compared to the 3DTi group (13.0%; p = 0.017). Multivariable Poisson regression adjusting for length of follow-up, number of levels treated and proximal level involvement, showed that 3DTi significantly reduced the risk of revision surgery (RR: 0.52, 95% CI: 0.30.0.90, p = 0.027), while no other factors were independently associated with revision risk. Among patients requiring revision (n = 41), a higher early failure rate within the first year was found with PEEK (36.4%) compared to 3DTi (10.1%), although non-significant (p = 0.058). The most common revision procedures were posterior spinal instrumentation at the caudal adjacent segment (22.0%), followed by proximal adjacent standalone LLIF (17.0%) and same segment decompression (14.6%). No difference in types of revision procedures were found between PEEK and 3DTi. Conclusion: 3D-printed Titanium cages significantly reduced the revision rate in standalone LLIF by half compared to PEEK, particularly in the early postoperative period. These findings suggest a biomechanical advantage of 3DTi that could impact surgical strategies for standalone LLIF. Further research is needed to explore the long-term benefits of 3DTi and standalone LLIF over other fusion techniques.

ID: 2074

A350: Evaluating the relationship between hip osteoarthritis and spinal degeneration in patients with de novo scoliosis

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

¹ Charité Universitätsmedizin Berlin, Berlin, Germany,

² Raylytic Software Gmbh, Leipzig, Germany

Introduction: The Hip-spine syndrome (HSS) describes a co-occurrence of hip osteoarthritis and degenerative spinal conditions, which persistently increase with age. While a coincidental occurrence of these conditions is common due to aging, the nature of their association remains ambiguous, raising questions about potential underlying connections beyond mere simultaneity. Existing clinical data have yet to definitively clarify whether the linkage between these conditions extends deeper than their shared association with advancing age. 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 prior hip replacement or spinal fusion operations, fractures, or spinal metastasis were excluded. Osteochondrosis was classified in EOS imaging and classified by the number of affected levels, grouped as 0, 1, 2-4 and ≥ 5 affected levels. Osteoarthritis was classified using the Kellgren and Lawrence classification, ranging from 0 to 4. In cases of bilateral hip osteoarthritis, the highest score was used. We performed univariable and multivariable logistic regression to evaluate the association between hip osteoarthritis and spinal osteochondrosis, which was adjusted for potential confounders, including age, sex, body mass index (BMI), and sagittal vertical axis (SVA). Results: A total of 326 patients (53.7% female) with a mean age of 71.5 (IQR 61 . 78) were included in the study. The mean osteoarthritis grade was 1(IQR 0 - 2). The analysis demonstrated a significant association between hip osteoarthritis and the likelihood of experiencing higher grades of spinal osteochondrosis in the univariable analysis (OR: 1.49, 95% CI: 1.21 - 1.85, p < 0.001) as well as after accounting for the confounders (Odds Ratio OR: 1.49, 95% CI: 1.21-1.85, p < 0.001). Age (OR: 1.07, 95% CI: 1.05-1.10, p < 0.001) and BMI (OR: 1.10, 95% CI: 1.04-1.16, p < 0.001) were also significant predictors, while SVA showed no significant effect (OR: 1.00, 95% CI: 0.99-1.00, p = 0.578) in the multivariable analysis. Discussion: This study shows a significant association between hip osteoarthritis and spinal osteochondrosis, independent of age, BMI, sex and sagittal spinal alignment. It suggests a deeper, possibly molecular link, such as collagen quality, that might predispose individuals to both conditions. Both age and BMI independently exacerbate these degenerative diseases, emphasizing the need for a comprehensive diagnostic approach in patients presenting with either hip or spine symptoms. The findings highlight the importance of considering co-morbid hip and spinal pathologies in treatment planning, which could lead to more effective management strategies and improved patient outcomes.

ID: 2046

A351: Does back pain catastrophizing influence 5-year surgical outcomes for patients with degenerative lumbar spondylolisthesis? A quality outcomes database study

Eunice Yang ¹ , Praveen Mummaneni ² , Dean Chou ¹ , Mohamad Bydon ³ , Erica Bisson ⁴ , Elan Schonfeld ¹ , Christopher Shaffrey ⁵ , Steven Glassman ⁶ , Kevin Foley ⁷ , Eric Potts ⁸ , Mark Shaffrey ⁹ , Domagoj Coric ¹⁰ , John Knightly ¹¹ , Paul Park ⁷ , Michael Wang ¹² , Kai-Ming Fu ¹³ , Jonathan Slotkin ¹⁴ , Anthony Asher ¹⁰ , Michael Virk ¹³ , Regis Haid ¹⁵ , Andrew Chan ¹

¹ Columbia University, New York, United States,

² UCSF, San Francisco, United States,

³ Mayo Clinic, Rochester, United States,

⁴ University of Utah, Salt Lake City, United States,

⁵ Duke University, Durham, United States,

⁶ Norton Leatherman, Louisville , United States,

⁷ Semmes-Murphey, Memphis, United States,

⁸ Goodman Campbell, Indianapolis, United States,

⁹ University of Virginia, Charlottesville, United States,

¹⁰ Carolina Neurosurgery & Spine Associates, Charlotte, United States,

¹¹ Maxim Spine, Morristown, United States,

¹² University of Miami, Miami, United States,

¹³ Cornell University, New York, United States,

¹⁴ Geisinger, Danville, United States,

¹⁵ Atlanta Brain and Spine, Atlanta, United States

Introduction: Degenerative lumbar spondylolisthesis is an important cause of back pain-influenced by factors including instability, disc degeneration, facet arthropathy, paraspinal radiculopathy, and psychosocial phenotype. The experience of high-severity pain is complex, with significant implications for surgical planning. The goal of this study is to assess the impact of severe pre-operative back pain on long-term outcomes following lumbar spondylolisthesis surgery. Material and Methods: We used the prospective Quality Outcomes Database cohort of patients undergoing single-segment surgery for grade 1 degenerative lumbar spondylolisthesis. Baseline NRS-Back Pain (NRS-BP) ≥ 8 was classified as “severe” and < 8 was classified as “mild-moderate” back pain. Patient-reported outcomes (PROs) were compared for patients with severe versus mild-moderate back pain at 60-months postoperatively. Multivariate analysis was conducted to assess impact of severe back pain on PROs, adjusting for variables reaching p < 0.20 on univariate analysis. Results: Of the 608 patients in the QOD dataset, 487 (80%) reached 60-month follow-up. A total of 260 (42.8%) had severe back pain and 348 (57.2%) had mild-moderate back pain at baseline. Patients with severe back pain were significantly younger (59.9 ± 2.2 vs 63.9 ± 11.7, p < 0.001), less often had ≥ 4 years college education (31.2% vs 42.5%, p = 0.004), and more often used private insurance (58.8% vs 47.7%, p = 0.01). The severe-pain cohort also had higher rates of depression (24.6% vs 17.0%, p = 0.02) and back pain symptom predominance (45.4% vs 32.2%, p < 0.001). Surgical and perioperative characteristics did not significantly differ between cohorts, though patients with severe back pain received slightly more fusions (74.1% vs 80.8%, p = 0.055). A similar proportion of patients across both cohorts received MIS (40.8% vs 45.0%, p = 0.30). The severe-pain cohort reported worse PROs at baseline and 60 months (p < 0.05). However, the magnitude of 60-month improvement was significantly greater across NRS-BP (-4.8 ± 3.2 vs -2.0 ± 3.1, p < 0.001), NRS-LP (-4.8 ± 3.7 vs -3.1 ± 3.8, p < 0.001), ODI (-25.9 ± 23.1 vs -19.1 ± 19.2, p = 0.001), and EQ-5D (0.2 ± 0.3 vs 0.2 ± 0.2, p = 0.008). Achievement of MCID at 60 months was also significantly greater for NRS-BP, NRS-LP, and EQ-5D (p < 0.05), though 60-month NASS satisfaction was not significantly different between cohorts. On multivariate analysis, severe back pain was significantly associated with 60-month NRS-BP change (OR = .1.44; 95% CI .1.80 to .1.08; p < 0.001) and MCID achievement (OR = 1.94; 95% CI 1.50 to 2.53; p < 0.001), but not with mean NRS-BP or other PRO metrics, including NASS satisfaction. Conclusion: Despite having worse baseline and 60-month outcomes, patients with severe back pain achieved substantially greater 60-month NRS-BP improvement and MCID achievement from surgery. However, patient satisfaction was comparable to the mild-moderate cohort. Our findings highlight the importance of appropriate expectation setting for patients with severe preoperative pain on the potential for substantial improvement, albeit with residual symptoms or disability.

OP40: Mis/Endoscopic Spine Surgery 2

ID: 205

A352: Innovative approaches in unilateral biportal endoscopic spine surgery: expanding the bounderies of minimally invasive techniques

Eric Astelo Belarmino ^1,2 , Agustin Miguel Morales ^1,2 , Jose Joefrey Arbatin ^1,2 , Oliver Ong ^1,2 , Lemuel Tonogan ²

¹ Chong Hua Hospital Fuente and Mandaue, Orthopedics, Spine Section, Cebu City, Philippines,

² Vicente Sotto Memorial Medical Center, Orthopedics, Spine Section, Cebu City, Philippines

Introduction: Unilateral Biportal Endoscopy (UBE) is at the forefront of minimally invasive spine surgery, offering significant advantages over traditional open approaches. UBE has been primarily employed for lumbar disc herniation and stenosis, providing benefits such as reduced soft tissue trauma, minimal bony resection, and faster recovery times. This paper presents a series of pioneering case studies that explore the innovative applications of UBE in spinal surgery, demonstrating its versatility in treating complex spinal pathologies beyond conventional indications. Material and Methods: We present 4 novel cases wherein UBE was selected as the treatment modality for conditions not commonly indicated in existing literature, highlighting the decision-making process and the rationale behind adopting these innovative approaches. Clinical outcome measure were pre- and postoperative visual analog scores and modified Macnab rating. Statistical significance were analyzed using paired t-test with a p value set to < 0.05. Results: Case 1 involves a 16-year-old male with a retained bullet fragment in the intervertebral disc space at the L5-S1 level. Traditional open surgery would necessitate extensive dissection and bony resection, potentially compromising spinal stability. UBE was utilized to remove the bullet fragment, preserving the posterior structures and minimizing soft tissue trauma. The patient experienced substantial pain relief and functional recovery, with a Macnab criteria rating of “good” at the 3-month follow-up. Case 2 details a 23-year-old male with a bullet fragment in the extraforaminal area at L4-L5. The paraspinal approach using UBE allowed for precise removal of the fragment, reducing the risk of iatrogenic instability and preserving spinal integrity. The patient's shooting pain significantly decreased, and motor function improved, demonstrating the technique's efficacy in managing extraforaminal pathologies. Case 3 features a 52-year-old male with severe lumbar stenosis and canal compromise at L4-L5. An innovative combination of Anterior-to-Psoas (ATP) lumbar interbody fusion and UBE provided both direct and indirect decompression. This approach effectively addressed posterior compression, offering enhanced visualization and minimizing soft tissue damage. The patient experienced immediate pain reduction, improved bladder function, and excellent clinical outcomes, with a Macnab criteria rating of “excellent” at 1-month post-surgery. Case 4 presents a 45-year-old female with a proximally migrated disc at L5-S1. The contralateral keyhole laminotomy using UBE allowed for targeted decompression with minimal bone resection, resulting in significant pain relief and no recurrence at the 3-month follow-up. This case exemplifies UBE's potential in addressing complex disc migrations with precision and minimal invasiveness. Conclusion: These innovative applications of UBE showcase its potential to revolutionize spinal surgery by extending its indications beyond traditional boundaries. The presented cases highlight UBE's versatility in managing diverse spinal pathologies, offering significant advantages over conventional methods. As technology and surgical expertise continue to evolve, UBE is poised to become a cornerstone of minimally invasive spine surgery, paving the way for future advancements in the field. This study aims to inspire further research and exploration into the myriad possibilities that UBE holds for the future of spine surgery.

ID: 2868

A353: Surgical outcomes following endoscopic decompression demonstrate no differences between obese and non-obese patients

Ryan Turlip ¹ , Hasan Ahmad ¹ , Yohannes Ghenbot ¹ , Daksh Chauhan ¹ , Mert Dagli ¹ , Kevin Bryan ¹ , John Arena ¹ , Connor Wathen ¹ , Dominick Macaluso ¹ , Ali Ozturk ¹ , Zarina Ali ¹ , Dmitriy Petrov ¹ , Neil Malhotra ¹ , Eric Zager ¹ , Paul Marcotte ¹ , Jang Yoon ¹

¹ University of Pennsylvania Perelman School of Medicine, Philadelphia, United States

Introduction: Endoscopic spine surgery is emerging as a frontier in minimally invasive spine surgery, offering shorter recovery periods and reduced postoperative pain by minimizing tissue damage. Discectomy is one of the most common procedures performed endoscopically, with evidence supporting comparable decompression outcomes to open procedures. However, the impact of obesity on outcomes in endoscopic spine surgery remains relatively underexplored. Studies have shown conflicting results on the effect of obesity on open lumbar microdiscectomy outcomes, with some demonstrating higher complication rates in obese patients. This study investigated whether obesity affects postoperative outcomes following endoscopic lumbar decompression surgery. Material and Methods: This retrospective study analyzed 124 consecutive patients who underwent transforaminal or interlaminar endoscopic lumbar decompression by a single surgeon between 2019 and 2023 at a multi-hospital academic center. Patients were stratified by body mass index (BMI), with 44 classified as obese (BMI > 30 kg/m²) and 80 as non-obese (BMI ≤ 30 kg/m²). Primary outcomes included postoperative patient-reported outcomes (PROs) such as Visual Analog Scale (VAS), EuroQol 5 Dimension (EQ5D), Oswestry Disability Index (ODI), PROMIS Physical Function (PF), PROMIS Pain Interference (PI), and PROMIS Depression. Secondary outcomes were intraoperative complications (e.g., CSF leaks, nerve injury, wound infection), length of stay (LOS), and reoperation rates. Propensity-scored stabilized inverse probability weighting (PS-SIPTW) was used to balance baseline characteristics between groups, and p-values were adjusted for multiplicity using the Benjamini-Hochberg correction. Results: Among the 124 patients, no significant differences were observed in postoperative PROs between obese comparted to non-obese cohorts across all metrics, including VAS (mean difference [MD] 0.3, 95% CI -0.7 to 1.3, adjusted p = 0.913), EQ5D (MD -0.5, 95% CI -7.8 to 6.9, adjusted p = 0.913), ODI (MD 1.8, -4.7 to 8.2, adjusted p = 0.913), PROMIS PI (MD 1.4, 95% CI -1.2 to 4.0, adjusted p = 0.913), PROMIS PF (MD -1.2, 95% CI -3.7 to 1.3, adjusted p = 0.913), PROMIS Depression (MD 0.5, 95% CI -3.1 to 4.1, adjusted p = 0.913). The mean length of stay was 21.1 ± 30.0 hours for obese patients and 45.9 ± 82.4 hours for non-obese patients (MD -24.8 hours, 95% CI -45.0 to -4.6 hours, adjusted p = 0.112). Total surgical time also did not differ significantly between the two groups. There were no significant differences in intraoperative complications, including CSF leaks, nerve injury, or wound infection, nor were there significant differences in reoperation rates. Conclusion: This study found no significant differences in postoperative patient-reported outcomes, complications, or reoperation rates between obese and non-obese patients following endoscopic lumbar decompression. These results suggest that obesity does not negatively impact outcomes in endoscopic spine surgery, and an endoscopic approach may help mitigate surgical risks associated with obesity. Future studies with larger cohorts are needed to further elucidate these findings.

ID: 1529

A354: Comparative outcomes of endoscopic versus microdiscectomy for lumbar disc herniation: a large-scale database analysis of short-term and long-term complications

Yi Zhang ¹ , Jialun Chi ² , Ved Vengsarkar ^2,3 , Rohan Boyapati ² , Hanzhi (Leo) Yang ² , Katelyn Kim ² , Xudong Li ² , Jin Li ²

¹ The Second Xiangya Hospital of Central South University, Department of Spine Surgery, Changsha, China,

² University of Virginia School of Medicine, Department of Orthopaedic Surgery, Charlottesville, United States,

³ Rutgers New Jersey Medical School, Department of Orthopaedic Surgery, Newark, United States

Introduction: Lumbar disc herniation (LDH) is one of the main causes of lower back pain. While conservative treatments are effective for many patients, some may still require surgical intervention, with discectomy being the most commonly performed procedure. Although there are various surgical techniques available for the initial operation, two widely employed surgical techniques for addressing lumbar disc herniation are endoscopic discectomy (ED) and microdiscectomy (MD). Compared to traditional open surgery, both ED and MD methods can be considered minimally invasive procedures, sharing common advantages of reduced patient trauma and faster postoperative recovery. In the current literature, there has not been a demonstrated consensus of one approach leading to superior clinical outcomes. Therefore, this study leverages the advantages of large-scale databases to compare the two surgical approaches by evaluating perioperative complications and complications during at least two years of postoperative follow-up, aiming to provide guidance for clinical decision-making. Material and Methods: A total of 1621 ED and 16,206 MD patients between the ages of 18-84 from 2017-2020 were identified within the PearlDiver database. Patients aged 18-84 undergoing LDH treatment between 2017 and 2020 were analyzed. The two cohorts, ED and MD, were matched based on age, sex, and Charlson comorbidity index, with a minimum of 2-year follow-up. Multivariable logistic regression was used to determine the independent effects of the surgical technique on the postoperative outcomes after adjusting for pertinent comorbidities. The study evaluated perioperative and 2-year postoperative complications. Results: The study found a significantly lower incidence of arrhythmia (2.5% vs 3.9%; p = 0.004) and urinary retention (1.4% vs. 2.1%; p = 0.049) in patients who underwent ED compared to MD within 90 days of surgery. Surgical complications, such as rates of dural tear (0.4% vs. 1.2%; p = 0.005), wound dehiscence (0.5% vs. 1.4%; p = 0.003), seroma (0.1% vs. 0.5%; p = 0.048), and deep wound infection (0.8% vs. 1.8%; p = 0.006) were also significantly lower in patients who underwent ED compared to MD within 90 days of surgery. However, ED was associated with a higher 2-year subsequent revision discectomy rate (13.2% vs. 5.9%; p < 0.001), shorter time, in days, to subsequent revision discectomy (343 ± 390 vs. 611 ± 732; p < 0.001), and shorter time, in days, to subsequent lumbar fusion (446 ± 390 vs. 742 ± 741; p < 0.001) questioning the long-term durability of this procedure compared to MD. Conclusion: Both ED and MD provide effective treatment for LDH with minimal invasiveness. ED offers benefits such as lower immediate postoperative complications and faster recovery but may require a careful consideration for long-term outcomes. This study contributes to ongoing discussions on the optimal surgical interventions for LDH and aids in clinical decision-making for treatment approaches.

ID: 1097

A355: Irrigation induced cerebrospinal fluid glucose wash-out during spine endoscopy with dural lesion: a proof of concept study

Jana Schader ^1,2,3 , Alexandra Stauffer ¹ , Carl Zipser ⁴ , Najmeh Kheram ^4,5 , Jonas Widmer ³ , José Spirig ¹ , Vincent Hagel ¹ , Mazda Farshad ¹

¹ University Spine Center Zurich, Balgrist University Hospital Zurich, University of Zurich, Zurich, Switzerland,

² Institute for Biomechanics, ETH Zurich, Zurich, Switzerland,

³ Spine Biomechanics, Balgrist University Hospital, Zurich, Switzerland,

⁴ Department of Neurology and Neurophysiology, Balgrist University Hospital, Zurich, Switzerland,

⁵ The Interface Group, Institute of Physiology, University of Zurich, Zurich, Switzerland

Introduction: Endoscopic spine surgery is a rapidly emerging minimal invasive procedure with a relatively low complication rate in trained hands. However, cerebral complications like seizure have been described and the pathomechanism remains unclear. Cerebrospinal fluid (CSF) composition changes through infection, electrolyte and metabolic disturbances may induce seizure. Therefore, we hypothesize that irrigation in the presence of a dural lesion might lead to changes in the CSF composition, e.g. hypoglycemia, which might trigger cerebral events during endoscopic spine surgery. Material and Methods: Interlaminar thoracic (T8/9) spine endoscopy was performed in two human cadavers after filling the dural sac with 20% glucose through a sacral approach. Irrigation pump pressure was set at 40 mmHg, irrigation was carried out using Ringer's solution. A dural lesion of 5x5 mm was performed at the T8/9 level. Additionally, a suboccipital puncture of the cisterna magna was performed by inserting a needle through a percutaneous C0/C1 approach. Position accuracy of the catheter was being verified through contrast enhanced X-ray imaging and ICP monitoring during filling the cisterna magna through the suboccipital approach. After first discarding 1ml, 1ml of fluid was extracted from the cisterna magna after 1, 3, 5, 10, 15, 20 and 30 minutes of irrigation. Stepwise glucose concentration measurements were conducted quantitatively by laboratory chemistry and visually by reagent strips. Results: During 30 minutes of thoracic endoscopic irrigation with 40 mmHg, the glucose concentration measured in the cisterna magna decreased from 12.0 mmol/l to 6.1 mmol/l and 28.0 mmol/l to 2.9 mmol/l in both specimens, respectively. This could be verified by visual control of the reagent strips. Conclusion: Intradural glucose concentration during interlaminar thoracic spine endoscopy in the presence of a dural lesion decreased by a factor of 2 to 10 compared to the initial level over the time course of 30 minutes in this proof-of-concept study. Changing cerebrospinal fluid composition through irrigation during endoscopic spine surgery in the presence of a dural lesion has to be considered as possible reason for cerebral complications.

ID: 2948

A356: Navigating through unchartered waters - A review of endoscopic anatomy of lumbar spine as seen via unilateral biportal endoscopic approach in 1000+ operated levels - Technical note and results

Ketan Dilip Deshpande ¹

¹ Saishree Hospital, Pune, India

Introduction: The advent of minimally invasive spine surgery has revolutionised the treatment of lumbar degenerative disorders, significantly reducing post-operative complications. This paper delves into the intricate anatomy crucial for successful unilateral biportal endoscopy (UBE) surger-ies on the lumbar spine, highlighting key observations and practical insights. Material and Methods: 1058 lumbar disc, decompressions and fusions done via Unilateral Bi-portal Endoscopic technique operated from September 2017 till August 2024 operated at single in-stitute by single surgeon were included for the study. Available video recordings of the surgeries were retrospectively analysed and consistently newer anatomical findings were documented and cross checked with pre-operative MRI pictures. The practical points are discussed along with rele-vant applied anatomy. Results: The results and their applications are enumerated below 1. Lamino-spinal to Lamino-facetal distance - to plan working space creation, 2. Ligamentum flavum to Interspinous connection - essential for Over the top decompression, 3. Caudal extension of ligamentum flavum - to expose junction of caudal lamina with superior articu-lar process (SAP), 4. Midline suspensory ligaments - to prevent incidental dural tears, 5. Axillary suspensory ligaments and Axillary blood vessels - to identify traversing nerve root, 6. Foraminal ligaments - for sufficient foraminal decompression, 7. Facetal orientation and hypertropy in lysthesis - to plan osteotomy, Having knowledge of the anatomy should decrease the hazards and facilitate a more seamless transition in the learning process for beginners. Conclusion: Overall, this paper offers a comprehensive understanding of endoscopic lumbar spine anatomy, addressing challenges faced by novice endoscopic surgeons and providing valua-ble guidance for a smoother transition into mastering Unilateral Biportal Endoscopic (UBE) proce-dures. Such knowledge is essential for mitigating risks, improving surgical outcomes, and facilitat-ing the learning curve in this advanced surgical domain.

ID: 221

A357: Can robot-assisted single-segment lumbar MIS-TLIF surgery really reduce intraoperative blood loss? A Propensity Score Matching (PSM) Study

Junxiao Su ¹ , Yang Yang ¹ , Weijie Cui ¹ , Hui Zhang ¹

¹ Gansu Provincial Hospital, Department of Orthopedics, Lanzhou, China

Introduction: MIS-TLIF is a common surgical procedure for treating degenerative lumbar diseases such as lumbar spinal stenosis and lumbar spondylolisthesis. Compared to traditional open surgery, it is associated with less intraoperative blood loss and shorter postoperative recovery times. Robot-assisted minimally invasive transforaminal lumbar interbody fusion (RA-MIS-TLIF) has gained popularity due to its improved accuracy in pedicle screw placement and reduced facet joint injury. However, there is a lack of research on blood loss during RA-MIS-TLIF surgery. Oozing into tissue interstitial spaces, pooling of blood at the surgical site, and hemolysis lead to invisible blood loss, known as hidden blood loss (HBL). Previous studies have compared HBL in TLIF and MIS-TLIF for the treatment of degenerative lumbar diseases. However, a comparison of HBL between patients undergoing MIS-TLIF with and without robotic assistance has not been studied. The purpose of this study is to compare the total blood loss and HBL in patients undergoing single-segment lumbar MIS-TLIF with and without robotic assistance, providing guidance for clinical practice. Material and Methods: Patients who underwent single-segment lumbar fusion surgery at a single center from January 2020 to March 2023 were collected according to the inclusion criteria. Basic information such as gender, age, height, weight, and blood-related indicators such as surgical segment, surgery time, intraoperative bleeding, blood transfusion, preoperative and postoperative hematocrit (Hct), hemoglobin (Hb), prothrombin time (PT), international normalized ratio (INR), activated partial thromboplastin time (APTT), and fibrinogen (FIB) were collected. Patients were divided into two groups based on the surgical method (RA group and non-RA group). After excluding confounding factors using propensity score matching (PSM), the data of the two groups were compared. Nadler's formula was used to estimate total blood volume (TBV), and Gross's formula was used to estimate total blood loss (TBL). Hidden blood loss (HBL) = TBL - visible blood loss + transfusion volume. Results: A total of 134 patients who underwent MIS-TLIF surgery were included in the study. After 1:1 PSM matching, 37 patients were included in each group. The average ages of the RA and non-RA groups were (57.1 ± 9.9 VS 57.3 ± 8.4, p = 0.930), BMI was (26.4 ± 3.4 VS 26.3 ± 2.7, p = 0.930), surgery time was (202.9 ± 69.4 VS 172.0 ± 45.8, p = 0.027), preoperative PT was (11.2 ± 0.6 VS 11.0 ± 0.8, p = 0.210), preoperative APTT was (30.5 ± 4.0 VS 31.5 ± 4.1, p = 0.312), preoperative INR was (0.97 ± 0.06 VS 0.94 ± 0.07, p = 0.560), preoperative FIB was (2.9 ± 0.7 VS 2.9 ± 0.6, p = 0.583), preoperative HB was (134.4 ± 9.7 VS 134.0 ± 13.0, p = 0.864), postoperative HB was (119.0 ± 12.0 VS 118.1 ± 14.2, p = 0.778), change in HB before and after surgery was (15.5 ± 7.8 VS 15.9 ± 9.2, p = 0.839), preoperative HCT was (40.3 ± 2.8 VS 40.1 ± 3.5, p = 0.790), postoperative HCT was (34.6 ± 3.4 VS 34.8 ± 3.5, p = 0.838), and change in HCT before and after surgery was (5.7 ± 2.1 VS 5.3 ± 1.6, p = 0.432). According to Nadler's formula, the results of TBV (total blood volume), TBL (total blood loss), and HBL (hidden blood loss) for the RA and non-RA groups were calculated. The RA and non-RA groups were as follows: TBV (3976.5 ± 661.6 VS 4077.3 ± 551.5, p = 0.479), TBL (594.9 ± 219.0 VS 573.0 ± 207.1, p = 0.659), HBL (496.5 ± 217.4 VS 474.6 ± 206.2, p = 0.657). Conclusion: Compared with non-robotic surgery, robot-assisted MIS-TLIF may not reduce the total blood loss and hidden blood loss.

ID: 2608

A358: Complication profile of lateral interbody fusion (LLIF): navigating the risks of a minimally invasive approach

Diego Soto Rubio ¹ , Molly Monsour ² , Samantha Schimmel ² , bryan clampitt ² , Petra Allen ² , Cesar Carballo ¹ , Jay I. Kumar 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, United States

Introduction: Minimally invasive spinal techniques have prioritized reducing morbidity while still obtaining adequate decompressive and reconstructive outcomes. Several techniques challenge the classical routes in search of alternative pathways to treat pathology, such as lateral lumbar interbody fusion (LLIF). LLIF is a minimally invasive procedure that, despite its benefits, presents a distinct set of complications if compared to traditional open surgeries. Some of the most associated risks may include lumbosacral plexus nerve injuries, groin pain, abdominal wall hernias, postoperative hematoma, and femoral nerve palsy. Recognizing and understanding these risks is essential to managing patients better, improving outcomes, and mitigating morbidity. Material and Methods: We performed a retrospective review of LLIF procedures conducted at our tertiary medical center between 2014 and 2022. Data on patient demographics, operative details, and intraoperative and postoperative complications was collected. Descriptive statistics, including frequencies for categorical variables and means with standard deviations for continuous variables, were performed using SPSS. Only patients with a minimum follow-up of six months were included in the analysis. Results: A total of 546 patients (M: 274; F: 272) undergoing 976 levels of LLIF were included, with a mean age of 62.86 years (range: 14-87). Among the 374 patients (632 levels) with follow-up exceeding six months, 82 patients (21.9%) experienced at least one postoperative complication. Medical complications included wound infections (5.9%), deep vein thrombosis (DVT) (3.2%), pulmonary embolism (PE) (1.1%), and myocardial infarction (MI) (0.5%). Neurological complications included acute thigh paresthesia (13.3%), transient weakness (11.2%), transient paresthesia (6.9%), femoral nerve palsy (1.1%), and hip flexion weakness (1.3%). Surgical complications included psoas hematoma (0.5%), abdominal wall hernia (0.75%), and bowel perforation (0.25%). Multilevel surgery was significantly associated with an increased risk of postoperative complications (p = 0.008), with complication rates rising from 17% in single-level procedures to 57% in four-level surgeries (p = 0.001). Conclusion: While LLIF offers a favorable risk-benefit profile in appropriately selected patients, it carries distinct risks. Particularly concerning complications may often include transient neurological deficits. Surgeons must be aware of the risks, especially in multilevel procedures, where complication rates increase significantly. Careful patient selection and thorough preoperative planning are essential to minimizing adverse outcomes.

ID: 1062

A359: Concordance between individual surgeon's endoscopic approach preference and expert recommendations. A global case-based survey

Facundo Van Isseldyk ^1,2 , Alfredo Guiroy ³ , Jahangir Asghar ³ , Javier Quillo-Olvera ^2,4 , Christoph J. Siepe ^5,6 , David Del Curto ⁷ , Marcus Vinícius Serra ⁸ , Alberto Gotfryd ⁹ , Cristian Ricardo Correa Valencia ¹⁰ , Marco Moscatelli ¹¹ , Lisandro Rodriguez Sattler ¹² , Fernando Nin ¹³ , Nicolas Prada Ramirez ¹⁴ , Muhammed Assous ^2,15 , Vincent Hagel ^2,16 , Mazda Farshad ^2,16 , Junseok Bae ¹⁷ , Yanting Liu ¹⁸ , Jin-Sung Kim ^2,18

¹ Hospital Privado de Rosario, Rosario, Argentina,

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

³ Elite Spine and Wellness Center, Fort Lauderdale, United States,

⁴ The Brain and Spine Care, Minimally Invasive Spine Surgery Group, Spine Center, Hospital H+, Department of Neurosurgery, Queretaro, Mexico,

⁵ Schön Clinic Munich Harlaching, Munich, Germany,

⁶ Spine Research Institute and Academic Teaching Hospital of the Paracelsus University Salzburg, Salzburg, Austria,

⁷ Federal University of São Paulo, School of Medicine, Sao Paulo, Brazil,

⁸ Santista Institute of Neurosurgery and Spine, Santos, Brazil,

⁹ Santa casa de São Paulo Medical School and Hospital, Sao Paulo, Brazil,

¹⁰ University of La Frontera, Orthopedic Department, Temuco, Chile,

¹¹ Clinica NeuroLife, Natal, Brazil,

¹² Asociación Española Primera de Socorros Mutuos, Montevideo, Uruguay,

¹³ Médica Uruguaya, Montevideo, Uruguay,

¹⁴ Clínica Foscal Internacional, Bucaramanga, Colombia,

¹⁵ Razi Spine Clinic, Amman, Jordan,

¹⁶ University Spine Center Zürich, Balgrist University Hospital, Zürich, Switzerland,

¹⁷ Wooridul Spine Hospital, Gangnam-Gu Seoul, South Korea,

¹⁸ The Catholic University of Korea, Seoul St. Mary's Hospital, College of Medicine, Department of Neurosurgery, Seoul, South Korea

Introduction: There are two major groups of full-endoscopic approaches to the lumbar spine: transforaminal (TF) and interlaminar (IL) approaches. Even when expert recommendation-based guidelines have been published to help surgeons select the most appropriate approach, different surgeons solve the same surgical case through other approaches. We present a Delphi-built case-based survey regarding global preferences for endoscopic approaches and their differences with expert’s recommendations. Material and Methods: This study consisted of two well-defined stages: In the first stage, experts and opinion leaders in endoscopic spine surgery developed five clinical cases focused on controversial topics. In the second stage, the five mentioned cases were used to create a survey distributed globally. Descriptive and inferential statistical analysis was performed. Results: Barely 32 respondents (21,19%) fully agreed with the expert's approach choices, and only 36% showed a balanced choice between IL and TF approaches. Individuals with more than 100 endoscopic practice cases have an 84.2% lower risk of preferring the IL approach compared to those with fewer than 100 cases (OR = 0.158, 95% CI: 0.034-0.746; p = 0.020). This indicates that extensive endoscopic experience influences surgeons to prefer the TF approach over the IL approach. Conclusion: This manuscript demonstrated heterogeneity of surgeon preference to select an endoscopic technique in a particular scenario, and that extensive endoscopic experience influences surgeons to prefer the TF approach over the IL approach.

ID: 786

A360: Endoscopic treatment of thoracolumbar spondylodiscitis: a sistematic review and meta-analysis

Enrico Giordan ¹ , Yanting Liu ² , Changik Lee ² , Jin-Sung Kim ²

¹ Aulss2 Marca Trevigiana, Neurosurgery, Treviso, Italy,

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

Introduction: Endoscopic surgery is a minimally invasive procedure that has been shown to relieve intradiscal pressure, irrigation of inflammatory factors, and visual debridement^, which are crucial for the successful treatment of spondylodiscitis. This study proposes a systematic review and meta-analysis to evaluate the effectiveness and safety of endoscopic treatment of thoracolumbar spondylodiscitis. Material and Methods: Multiple databases were searched for studies involving thoracolumbar spondylodiscitis treated by endoscopic disc drainage with or without additional posterior fixation over the last ten years. Studies that met the inclusion criteria, which included outcomes related to the percentage of cured infections, patient satisfaction, regression of inflammatory markers, and/or the percentage of adverse event rates, were included in the analysis. For each study, the percentage of patients who showed improvement or experienced an adverse event was abstracted and pooled in a meta-analysis. Results: Based on the search strategy and inclusion criteria, our systematic review and meta-analysis included 20 studies with 546 participants. The success rate was 89.4% (95% CI 83.1%-94.5%). The rate of major adverse events was 0.3%, while that of postoperative transient paresthesia 2.6% (95% CI 0.8%-5.1%). The recurrence rate was 1.7% (95% CI 0.3%-4.0%), and revision surgery was 8.5% (95% CI 3.8%-14.6%). The causative pathogen diagnosis rate was 73.9% (95% CI 67.7%-79.8%), while progression of deformity was 3.7% (95% CI 0.2%-9.8%), and spontaneous fusion was 40.1% (95% CI 11.0%-73.3%). Conclusions: Endoscopic discectomy for thoracolumbar spondylodiscitis has been shown to be a safe technique with satisfactory clinical outcomes and a high causative pathogen identification rate.