< Previous10 Abstracts CONCURRENT SESSION 3: FREE PAPERS 1–12 Paper 6:Outcomes and Complications After Anterior Lumbar Interbody Fusion with Percutaneous Pedicle Screws for Grade II/III Isthmic Spondylolisthesis Mauro Tavares Junior, MD - University of Kansas Medical Center; Andre Jakoi, MD - Orthopedic Health of Kansas City; Peter Derman, MD, MBA - Texas Back Institute; Joshua Bunch, MD - University of Kansas Medical Center; Jake Kreck, PA-C - Texas Back Institute; Brandon B. Carlson, MD, MPH - University of Kansas Medical Center Introduction: Isthmic spondylolisthesis (IS) incidence is 2.6-4.4% and most commonly occurs at L5-S1. When IS is treated surgically, if fusion is indicated the posterolateral and/or interbody surfaces can be used for arthrodesis. Anterior lumbar interbody fusion (ALIF) has many appealing characteristics compared to posterior-based interbody techniques. ALIF plus percutaneous pedicle screws (PS) is poorly studied in Grade II/III IS. It is postulated that ALIF for higher grade IS may have high rates of postop radiculopathy, stretch neuropraxia, and/or nerve root injury, and these risks may explain why so few studies exist on this topic. Objectives: The objective was to analyze Grade II/III IS treated with ALIF and PS without decompression to determine clinical and radiographic outcomes, radiculopathy, and reoperation rates. Methods: A multicenter review was performed on all single-level IS patients treated with ALIF plus PS without decompression. All subjects had minimum 90-day follow-up. Variables collected were: age, gender, BMI, IS grade, cage dimensions/lordosis, pre and postoperative measurements of listhesis, and percentage reduction. Presence of radiculopathy was assessed by clinical documentation of leg pain and/ or weakness, oral steroids prescribed within 90 days, spinal injections at the surgical level, or reoperation for radiculopathy. Results: 56 cases (55.4% female) were identified and analyzed. Mean age was 59±15yrs (33-83) and BMI was 32.0±6 (20- 49). Surgical levels were: L5-S1 (51), L4-L5 (4), and L5-L6 (1). There were 50 (89.3%) Grade II and 6 Grade III. Mean cage dimensions were Width (36.8±2.3mm), Depth (29.5±5.2mm), and Posterior Height (8.5±1.8mm). Cage lordosis was 20 degrees (46), 15 (8), 25 (1), and 16 (1). PreOp listhesis ratio (mm translation/mm length of superior endplate of caudal vertebra) was 0.37±0.09 and PostOp was 0.08±0.07. Mean reduction percentage was 78±18%. There were 8 (14.3%) radiculopathy cases. 6 patients were prescribed oral steroids. There was 1 reoperation (1.8%) for weakness noted on postop day 1. Foraminotomy was performed and the weakness resolved. All patients had resolution of radiculopathy by 90- day follow-up. Conclusion: In a multicenter series of Grade II/III IS surgically treated with ALIF plus PS and no decompression, we observed a 14.3% rate of transient postop radiculopathy and only 1.8% reoperation rate. ALIF plus PS without direct nerve root decompression is an acceptable minimally invasive technique for treating higher grade isthmic spondylolisthesis. Surgeons should use this information to educate patients that transient postop radiculopathy may occur but reoperation is rare. Paper 7: The Incidence of Complications and Neurological Deficits in Split Tubular, Endoscopic, and Robotic-assisted Endoscopic TLIFs: There Is a Difference Michael Gerling, MD - Gerling Institute; Melissa Baker - Gerling Institute; Evan Chaladoff - Gerling Institute; Zorica Buser, PhD MBA - Gerling Institute Introduction: Increase in fusion procedures, improvements in spinal technology, and outpatient setting have led to a substantial increase in minimally invasive Transforaminal Lumbar Interbody Fusions (TLIFs). Aims/Objectives: The aim of the current study was to evaluate if there are differences in the incidence of post- operative complications between three MIS TLIF techniques: standard split tubular, endoscopic, and Robot-assisted endoscopic TLIF. Methods: Patients who underwent single or multi-level TLIF between 2020 and 2022. Demographic and intra-operative variables (type of TLIF, levels, surgery time, blood loss, length of stay) were recorded. Data on post-operative medical and transient neurological complications (radiculitis) were collected. Chi-squared test with Bonferroni adjustment was used to compare groups and complication rates, with p< 0.025 being significant. Multivariate regression will be used to analyze the correlation between TLIF procedures and complication rates while controlling for demographics and intra-operative variables. Results: The current study included 147 patients undergoing TLIF. The average patient age was 47.8±11.1 years, with 68% of the patients being male. 88% of the patients had ASA grade II and 12% grade III. 16% of the patients were frequent smokers, 5% were “sometimes” smokers, and 79% were never smokers. 80% of the patients underwent single level TLIF, while 19% and 1% of patients underwent 2 level and 3 level 11 Please Click Here to VIEW Presenter Disclosures CONCURRENT SESSION 3: FREE PAPERS 1–12 TLIF, respectively. 26% of patients underwent endoscopic, 60% underwent tubular TLIF, and 14% were endoscopic with robotic guidance. At 2 weeks post-operatively, tubular TLIF had the lowest incidence of any complication (13.6%) compared to Endo (26.3%, p=0.0853) or Robot-assisted TLIF (23.8%, p=0.25). All complications in Endo and Robot- assisted TLIFs were neurological complication (radiculitis). In the tubular TLIF, 64% were radiculitis, 29% wound, and 7% DVT (1 patient) complications. When comparing the incidence of transient neurological complications, tubular TLIF had significantly lower incidence compared to Endo TLIF, 10.2% vs. 26.3% p=0.0206. Similarly, tubular TLIF had substantially lower incidence of radiculitis when compared to Robot- assisted (10.2% vs. 23.8% p=0.0946). At 3 months there was one new neurological complication in the tubular TLIF and one in the Endo TLIF at 6 months. Conclusions: The current study demonstrated that tubular TLIF had lower complication rates than both Endo and Robot- assisted TLIF procedures. There were significantly fewer neurological complications in the tubular group compared to Endo TLIF. Some of the limitations included learning curve, lack of randomization, and use of BMP2. Paper 8: Two-Year Outcomes of Full- endoscopic Versus Open Discectomy for Sciatica Pravesh S. Gadjradj - Weill Corneill; Biswadjiet Sanjay Harhangi, MD, PhD - Park MC Background: Open microdiscectomy (OM) is the current standard procedure to treat sciatica caused by lumbar disk herniation. Percutaneous transforaminal endoscopic discectomy (PTED) is an alternative procedure which is performed under local anesthesia. Here we report the long- term results. Methods: A pragmatic, multicenter, non-inferiority, randomized controlled trial was conducted in which patients were randomized between PTED or OM in a 1:1 ratio. The primary outcome is self-reported leg pain measured by the 0-100 Visual Analogue Scale (VAS) with a non-inferiority margin of 5. Secondary outcomes include self-reported ODI, back pain, costs, QALYs, health-related quality of life and self-perceived recovery. Outcomes were measured the day following surgery, at 2, 4, and 6 weeks, and at 3, 6, 9, 12, and 24 months. Results: A total of 613 were randomized to either PTED (n=304) or OM (n=309). At 24 months, 92% of the patients had follow-up data available. At 24 months, the adjusted between group difference of the VAS leg pain was 7.3 in favor of PTED (17.0 ± 22.4 vs. 24.3 ± 26.5). There was no difference in back pain at 24 months between both groups. All other secondary patient-reported outcomes showed small but statistically more favorable results for the PTED-group. Complication rates and rate of recurrent disc surgery (PTED 6.7%; OM 8.7%) appear similar between both groups. Except for costs of the surgery itself, all other costs were lower for PTED than OM. Cost-effectiveness acceptability curves indicated that the probability of PTED being cost-effective compared with OM was almost 100% for leg pain and QALYs, regardless of the willingness-to-pay. Conclusion: PTED is non-inferior and cost-effective to OM in the treatment of sciatica at 24 months of follow-up, and clinical outcomes appear to be more favorable for PTED, albeit not exceeding established MCIDs. Therefore, based on these study results, implementation of PTED as a treatment option for sciatica is warranted. Paper 9: Robotics Reduces Radiation Exposure in Minimally Invasive Lumbar Fusion Compared To Navigation Pratyush Shahi; Avani Vaishnav; Kasra Araghi; Daniel Shinn; Junho Song - Hospital for Special Surgery; Sidhant Dalal; Dimitra Melissaridou; Eric Mai; Marcel Dupont; Evan Sheha; James Dowdell; Sravisht Iyer; Sheeraz Qureshi Introduction: Navigation and robotics decrease the dependence on fluoroscopy and thus have been reported to reduce surgeons’ exposure to ionizing radiation. Although studies have been conducted comparing radiation exposure with robotics or navigation to that with traditional fluoroscopy, there has been no such comparative study between robotics and navigation. Objectives: To compare robotics and navigation for minimally invasive transforaminal lumbar interbody fusion (MI-TLIF) in terms of fluoroscopy time and radiation dose. A secondary objective was to compare the operative time demand. Study design: Retrospective cohort Patient population: Patients who underwent elective one- or two-level MI-TLIF by a single surgeon using navigation (Stryker SpineMask, Stryker Corp., Kalamazoo, MI) or robotics (ExcelsiusGPS, Globus Medical Inc, Audubon, PA) were included (navigation 2017-19, robotics 2019-21, resulting in prospective cohorts of consecutive patients for each 12 Abstracts modality). All surgeries had the intraoperative CT workflow. Outcome measures: 1) operative time (time of incision to time of closure), 2) time for setup and image capture (induction end time to incision time), 3) total operating room (OR) time (in room to out of room time), and 4) radiation exposure (fluoroscopy time for surgical procedure, fluoroscopy time for image capture, total fluoroscopy time, % of radiation for surgical procedure, % of radiation for image capture, and total radiation dose). Statistical analysis: The two cohorts were compared using Chi square test and Fisher’s exact test for categorical variables, and student t-test and Mann Whitney u-test for normally and non-normally distributed continuous variables, respectively. Results: 244 patients (111 robotics, 133 navigation) were included. The two cohorts were similar in terms of baseline demographics, primary/revision surgeries, and fusion levels. One-level TLIFs: Total fluoroscopy time, total radiation dose, and % of radiation for surgical procedure were significantly less with robotics compared to navigation (20 vs. 25s, p< 0.001; 38 vs. 42mGy, p=0.05; 58 vs. 65%, p=0.021). Although time for setup and image capture was significantly less with robotics (22 vs. 25 min, p< 0.001) and operative time was significantly greater with robotics (103 vs. 93 min, p< 0.001), there was no significant difference in the total OR time (145 vs. 141 min, p=0.25). Two-level TLIFs: Similar findings as one-level both in terms of radiation exposure and time demand. Conclusions: Robotics compared to navigation leads to a significant reduction in radiation exposure both for the surgeon and the patient. Although it does lead to a slight increase in the OR time, it is not statistically significant. Paper 10: Incidence of Radiographic and Clinically Significant Pneumohemothorax after Minimally Invasive Lateral Retropleural Approach for Thoracic Disc Herniation: Consecutive Case Series Nima Alan; S. Harrison Farber, MD - Barrow Neurological Institute; James Zhou - Barrow Neurological Institute; Steve S. Cho, MD, MS - Barrow Brain and Spine; Luke O'Neil; Robert K. Dugan; Kate L. Petty; Laura Snyder; Jay Turner; Juan Uribe Introduction: Minimally invasive lateral retropleural (MIS- LRP) approach has been described as an effective technique to address thoracic disc herniation. A common concern in this approach is the violation of parietal pleura. Some surgeons advocate prophylactic placement of chest tube. However, chest tube placement results in insertion site tenderness, potentially increasing analgesia/narcotic requirements, necessitates general surgery consultation, increases radiation exposure due to multiple radiographs, and delays progression of care. In this study we examine the incidence of radiographic and clinically significant pneumothorax (PTX) after MIS-LRP approach for thoracic disc herniation. Methods: This is an IRB-approved single institution retrospective study of consecutive cases from 2017 to 2022. Electronic medical charts were reviewed. Postoperative chest x-ray, radiology and operative reports, as well as postoperative physician and nursing notes were reviewed. Presence of PTX was determined on routine postoperative chest x-ray obtained for all patients. Size of PTX was dichotomized to large (>=3 cm) and small (< 3cm) based on American College of Chest Physician guideline. Clinically significant pneumothorax was defined as chest tube placement, and/or re-intubation. Results: Twenty-nine patients (32 levels) underwent thoracic discectomy via MIS-LRP approach by three surgeons during the study period. All patients were included. Most patients were male (n=20), with age range 25-74 years old, and BMI range 19.5-43.9. Most common treated level was T11-T12 (n=11). Intraoperative violation of pleura was noted in one patient. None of the patients received prophylactic chest tube. Fourteen patients had PTX on immediate postoperative chest x-ray (14/29; 48.2%): n=1 was large, the rest (n=13) were small. Repeat chest x-ray showed expansion of PTX in n=2 patients, requiring chest tube. One patient presented with shortness of breath on postoperative day 6 due to hemothorax requiring chest tube. Thus, total of n=3 required chest tube (3/29; 10.3%). None of the patients required reintubation. Conclusion: The majority of patients who undergo thoracic discectomy via MIS-LRP do not develop clinically significant PTX, obviating the need for prophylactic chest tube. Pneumothorax in this patient population should be treated with chest tube on an as-needed basis. CONCURRENT SESSION 3: FREE PAPERS 1–12 13 Please Click Here to VIEW Presenter Disclosures Paper 11:Early Compensatory Segmental Angle Changes at L3-L4 and L4-L5 Following a L5-S1 Anterior Versus Transforaminal Lumbar Interbody Fusion Bailey O'Connor - Virginia Mason Franciscan Health, University of Washington School of Medicine; Gina Canlas - Virginia Mason Franciscan Health; Caroline Drolet - Virginia Mason Franciscan Health; Jesse Shen - Virginia Mason Medical Center; Venu Nemani - Virginia Mason Franciscan Health; Jean-Christophe Leveque - Virginia Mason Franciscan Health; Rajiv Sethi - Virginia Mason Franciscan Health; Philip K. Louie - Virginia Mason Franciscan Health Introduction: As degenerative and chronic isthmic spondylolistheses progress over time at L5-S1, a decrease in the segmental lordosis at this level is often observed. This often progresses to lordotic overcompensation at the adjacent levels in an attempt to maintain spinopelvic balance. The fate of the adjacent angles following interbody fusion has not been well described. Aims/Objectives: To compare the early reciprocal changes seen at the L3-L4 and L4-L5 adjacent levels 6 months following an anterior (ALIF) or transforaminal (TLIF) lumbar interbody fusion at L5-S1. Methods: Patients who underwent a L5-S1 ALIF or TLIF with posterior pedicle screw instrumentation for a grade 1 spondylolisthesis between January 1, 2018 and November 1, 2021 were included in this study. Preoperative and 6-month postoperative measurements were made on sagittal standing radiographs: segmental lordosis (L3-L4, L4- L5, and L5-S1), lumbar lordosis, and pelvic incidence. We performed preliminary t-tests for descriptive purposes and multiple regression for our main hypothesis testing. Results: We identified 70 patients who met our inclusion criteria (35 ALIF and 35 TLIF). For both the overall lordosis (ALIF 4.6 deg, TLIF -4.3 deg) and at L5-S1 (ALIF 10.5 deg and TLIF -2.2 deg), ALIF procedures led to greater lordotic change than TLIF procedures (p < 0.001). A greater amount of lordosis achieved at L5-S1 was associated with a greater reduction of segmental lordosis at L4-L5 and L3-L4 (p = 0.02). In fact, a greater change in the compensatory lordosis (return to neutral) at L4-L5 predicted a similar change at L3- L4 (p = 0.02). Thus, patients that underwent an ALIF at L5- S1 demonstrated greater amounts of compensatory loss of segmental lordosis at L4-L5 and L3-L4 compared to those that underwent a TLIF. Conclusion: In patients who underwent a L5-S1 ALIF or TLIF with posterior pedicle screw instrumentation for a grade 1 spondylolisthesis, we observed greater segmental L5-S1 lordosis in those that underwent an ALIF compared to those undergoing a TLIF. Six months following surgery, greater compensatory changes (lordosis reduction) are observed at the L4-L5 and L3-L4 adjacent levels in patients undergoing an ALIF at L5-S1. Interestingly, the amount of lordosis correction at L5-S1 directly impacts the amount of compensatory loss of lordosis (return to neutral) at L4-L5, which in turn affects the change in segmental lordosis at L3- L4. This is suggestive of an indirect effect of the operative L5-S1 segmental angle change and procedure interaction through L4-L5 angle change on L3-L4. Paper 12:7-year Patient-reported Outcomes (PRO) After Lumbar Total Disc Replacement: A Post Hoc Analysis of a Prospective Clinical Trial with 7-year Follow-up Jack Zigler; Domagoj Coric; Peter B. Derman, MD, MBA - Texas Back Institute; Ernest E. E Braxton, MD, MBA - Vail Summit Orthopaedics and Neurosurgery; Kris Radcliff - Rothman Orthopedics; Glen Buttermann; Anton Jorgensen; Aaron Situ; Nicole Ferko; Leena Patel Introduction: Lumbar degenerative disc disease (DDD) is a spinal disorder that can have substantial impacts on patient quality of life, primarily due to pain and subsequent dysfunction in activities. There are several methods and dimensions for measuring PROs in spinal surgery. Objectives: To characterize differences between activL® Artificial Disc and ProDisc-L lumbar total disc replacement (TDR) for several types of PROs. Seven-year follow-up data from a prospective, multicenter Food and Drugs Administration (FDA) Investigational Device Exemption (IDE) randomized controlled trial were used for this evaluation. Methods: Patients with single-level, symptomatic lumbar DDD who were unresponsive to ≥6 months of nonoperative care were randomized to receive activL (n=218) or ProDisc-L (n=65). Patient-reported outcomes assessed included the SF-36 physical and mental component scores (PCS, MCS), narcotics use, return to work, and questions related to satisfaction with treatment. Two-sample t-test and Fisher’s exact tests were used to explore differences between treatment, and time-to-event data were analyzed using Kaplan-Meier methods. Regression models were used to identify predictors of self-reported outcomes. Multiple imputation was used for missing data. CONCURRENT SESSION 3: FREE PAPERS 1–12 14 Abstracts Results: At baseline, SF-36 scores were comparable between activL and ProDisc-L. At 7 years, mean MCS (activL, 17.2 points; ProDisc-L, 18.3 points) and PCS (activL, 13.1 points; ProDisc-L, 11.4 points) significantly improved compared with baseline (both P=0.0001). Median time to return-to-work was 67 days for activL and 74 days ProDisc-L (p=0.34). Opioid utilization declined to 0% after 7 years for both TDR groups (p=0.01). Improvements in these outcomes were largely achieved in the first year after surgery and were maintained to 7 years. Patient satisfaction outcomes aligned with other PROs, with excellent results achieved across questions for both TDRs and a trend towards higher improvement with activL. Specifically, 97.2% (207/213) of patients with activL and 91.9% (57/62) with ProDisc-L reported willingness to have surgery again (p=0.075), 90.6% (193/213) and 82.3% (51/62) reported they felt treatment was effective in eliminating symptoms (P=0.1072), and 95.3% (203/213) and 93.5% (58/62) reported being satisfied with treatment (p=0.526). There were no statistically significant baseline predictors found for SF-36 outcomes; however, preoperative narcotic use was negatively associated with returning to unrestricted full-time work activities. Conclusions: Various types of PROs, including physical, mental, and satisfaction measures, improved considerably from baseline to long-term follow-up. Gain achieved in the first year was maintained to 7 years. Paper 13:Single Position Transpsoas Corpectomy and Posterior Instrumentation in the Thoracolumbar Spine for Different Clinical Scenarios Alfredo J. Guiroy - Elite Spine Health and Wellness Center; Jahangir Asghar - Elite Spine Health and Wellness Center; Ashish Patel - Duly Health and Care; Alex Thomas - Atlantic Brain and Spine, Wilmington; Michael Rogers - Duly Health and Care; Gaston Camino-Willhuber - UCI Medical Center; Justin Seale; Cristiano Menezes; William Smith; Gergely Bodon Introduction: Single position spine surgery for disc pathologies has been gaining momentum as it has proven to reduce operative time, blood loss, and hospital length of stay with similar or better outcomes than traditional dual-position surgery. Objectives: The objective of this study is to describe and discuss a multicentric case series of patients treated by single position corpectomy (SPC). Methods: Multicenter retrospective study of patients treated using a single position corpectomy (SPC) of the thoracic or lumbar vertebra. The following data was collected from each center involved: demographics, diagnosis (trauma, tumor, or infection), neurological status, comorbidities, surgical approach and procedure (single position lateral or prone lateral), number of instrumented levels, intraoperative parameters (length of surgery, estimated blood loss, transfusion), postoperative parameters (time to mobilization, length of stay, days spent in the Intensive care unit), complications, reoperation and readmissions, and radiological variables. The minimum follow-up for inclusion was six months. Results: 34 patients were included (24 males, 10 females), with a mean age of 51.2 years. The diagnoses that motivated the corpectomy were: trauma (n=26), tumor (n=5), infections (n=2), and a revision PSO (n=1). The most common level affected was L1 (n=11) followed by L3 (n=8) and L2 (n=6). In 27 cases the corpectomy was done in lateral single position and in 7 in prone. Mean surgical time was 173.2 min, estimated blood loss 498 ml, and length of hospital stay 8.1 days. Segmental angle average changes were from 19º kyphosis to 2º or lordosis. As complications we had 2 returns to the operating room (1 persistent stenosis and 1 wound infection). Conclusion: This is the first multicentric series of patients that underwent single position corpectomy and fusion. This technique has shown to be safe and effective to treat a variety of spinal conditions with a relatively low rate of complications. More series are required to validate this technique as a possible standard approach when thoracolumbar corpectomies are indicated. Paper 14: Cervical Disc Arthroplasty and Range of Motion at 7-years: Impact on Adjacent Level Degeneration Alexander M. Satin, MD - Texas Back Institute; Mary P. Rogers-LaVanne, PhD - Texas Back Institute; Peter B. Derman, MD, MBA - Texas Back Institute Introduction: One benefit of cervical disc arthroplasty (CDA) compared to anterior cervical discectomy and fusion (ACDF) is maintenance of index level range of motion (ROM). However, recent studies highlight the potential for either hypo- or hyper-mobility to contribute to spinal pathologies, and little is known about hypo- and hyper-mobility after CDA. CONCURRENT SESSION 4: FREE PAPERS 13–2415 Please Click Here to VIEW Presenter Disclosures Objectives: The preservation of ROM for CDA patients may decrease stress at adjacent levels and therefore reduce progression of adjacent level degeneration (ALD). This study compares ALD progression after ACDF versus CDA and further assesses the relationship between ROM after CDA and ALD progression. Methods: A secondary analysis was conducted on seven- year follow-up data from a prospective, randomized (2:1), multicenter, 2-arm, noninferiority IDE clinical trial for 1-level Mobi-C (n=163, ClinicalTrials.gov Identifier: NCT00389597). ALD and index level flexion-extension ROM were measured with radiographic assessments. Dichotomous variables were assessed using the chi-square test. Continuous data was assessed using one-way analysis of variance (ANOVA). Alpha was set at 0.05. Results: ACDF patients experienced significantly more ALD progression than CDA patients (p=0.002 at the superior and p=0.049 at the inferior level). At the superior level, 65.1% ACDF patients versus 37.2% of CDA patients experienced ALD progression. At the inferior level, 62.9% ACDF patients versus 39.8% CDA patients experienced ALD progression. ROM seven years after CDA was binned in quartiles ranging hypomobile, mid-ROM, and hypermobile states (0-5.5°, 5.5-9.6°, 9.6-15.6°, and 15.6-28.5°). The increase in ALD score from pre-surgical baseline was significantly different (p=0.046 at the inferior level). Patients with the lowest and highest ROM after CDA experienced the largest increases from baseline ALD, where 48.1% patients with 0-5.5° ROM and 51.6% patients with 15.6-28.5° ROM experienced ALD progression. The relationship between demographic variables and ROM after CDA was analyzed. Age and sex were both associated with ROM, where patients with the highest ROM tended to be younger (p=0.023) and women (p=0.001). Conclusion: Patients who underwent ACDF experienced significantly more ALD progression at 7-years than patients who underwent CDA. While maintaining ROM after CDA may be more protective against ALD compared to ACDF, 39.8% CDA patients experienced ALD at the inferior level. Investigating variation within CDA patients demonstrates that those with the lowest and highest ROM after CDA have similar rates of ALD progression and greater increases in ALD compared with those who maintain a mid-ROM after CDA. This suggests that both hypo- and hyper-mobility after CDA may contribute to ALD progression. Paper 15: Multimodal Analgesic Protocol for Cervical Disc Replacement in the Ambulatory Setting: Clinical Case Series Michael C. Prabhu, BS - Rush University Medical Center; James W. Nie, BS - Rush University Medical Center; Timothy J. Hartman, BS - Rush University Medical Center; Kevin C. Jacob, BS - Rush University Medical Center; Madhav R. Patel, BS - Rush University Medical Center; Keith R. MacGregor, BS - Rush University Medical Center; Omolabake O. Oyetayo, BS - Rush University Medical Center; Eileen Zheng, BS - Rush University Medical Center; Kern Singh, MD - Rush University Medical Center Introduction: Effective pain control is paramount for surgical success in the ambulatory setting. Objective: The present study reports a clinical case series of patients undergoing cervical disc replacement (CDR) in an ambulatory surgical center (ASC) with the use of an enhanced multimodal analgesic (MMA) protocol. Methods: Patients with primary CDR procedures in an ASC with an enhanced MMA protocol were retrospectively included. Patients indicated for infectious/malignant/ traumatic etiologies were excluded. Patient demographics and preoperative characteristics were stratified by the number of levels operated on. Patient-reported outcome measures (PROMs) were collected preoperatively and at distinct time points postoperatively and included PROMIS-PF/VAS neck/ VAS arm/NDI/SF-12 PCS/MCS which were compared both within and between groups. MCID achievement was determined using values established in literature. Results: 106 patients were included with 76 undergoing single level CDR and 30 patients undergoing 2-level CDR. Mean narcotic consumption on POD 0 measured in oral morphine equivalents was 16.9 for single-level CDR and 18.5 for two-level CDR. One patient (0.9%) who underwent two- level CDR at C5-C7 was re-hospitalized for revision surgery after development of hematoma 5 days following surgery. This patient was readmitted to hospital, cervical drain was placed, and patient was discharged 2 days later. Both cohorts demonstrated statistically significant improvements from preoperative baseline for all PROMS at all postoperative time points, except SF-12 MCS at 1-year and 2-years and SF-12 PCS at 2-years (p< 0.047, all). Conclusion: This study demonstrates the efficacy of performing CDR surgery with an enhanced MMA protocol in an outpatient setting with proper patient selection and surgical technique. Patients in this cohort were discharged in a timely manner, had well-controlled postoperative pain, and demonstrated favorable long-term outcomes. CONCURRENT SESSION 4: FREE PAPERS 13–2416 Abstracts Paper 16:Proximal Adjacent Segment Disease Over Ten Years After Lateral Lumbar Interbody Fusion Molly Monsour, BS - USF Health Morsani College of Medicine; Elliot Pressman, MD - USF Health Morsani College of Medicine; Deborah Liaw, BS - USF Health Morsani College of Medicine; Puya Alikhani, MD - USF Health Morsani College of Medicine Introduction: Lateral lumbar interbody fusion (LLIF) is one modality used to treat degenerative spine disease. While sometimes used as a standalone technique, it is often supplemented by posterior instrumentation. Given its distinct alteration of biomechanics, it subjects the spine to different loading forces and may change the rates of adjacent segment disease (ASD). Our goal was to find factors that may predispose patients to the development of ASD. Methods: We conducted a retrospective cohort study on all patients who underwent LLIF at a single academic center between 2012 and 2021 with at least four years of follow- up. Patients without a lateral fusion at the top level of their construct were excluded. Proximal ASD was defined as a patient with previous surgery that developed back pain, claudication, or radiculopathy with imaging showing failure at the proximal adjacent level that required surgical intervention. Demographics and operative variables were analyzed. Results: 75 patients, comprising 117 levels, fit inclusion and exclusion criteria. 17 patients had ASD a median of 2312 days after index surgery. There was no difference in demographics between those who developed ASD and those who didn’t. An average of 1.57 (No ASD) vs. 1.53 (ASD) lateral levels were fused in each case (p=0.875). Standalone lateral fusions at the top level of a construct approached significance in being protective of ASD (No ASD: 22 (37.9%) vs. ASD: 2 (11.8%), p=0.073). More levels of posterior instrumentation in the index case approached significance in decreasing rates of ASD (No ASD: 1.10±0.326 vs. ASD: 1.71±0.636, p=0.0856). The lowest lateral instrumented vertebra (LLIV) was statistically associated with rates of adjacent segment disease (p=0.012), suggesting that between L3, L4, and L5, ending a lateral fusion at L4 predisposed patients to ASD. Through stepwise logistic regression, L4 as the LLIV (Odds Ratio (OR)=7.687, 95% Confidence Interval (95CI)=2.03-29.1, p=0.003) and increasing numbers of posterior levels instrumented in the index case (OR=1.78, 95CI=1.10-2.87, p=0.019) were associated with ASD. Analyzing patients with proximal junctional kyphosis (PJK; a severe subset of ASD), ACR was associated with a significant increase of PJK (No ASD=1 (1.4%), ASD=2 (66.7%), p=0.003). Conclusion: In patients with LLIF independently, or as part of a larger construct, using L4 as the LLIV, and increasing numbers of posteriorly instrumented vertebrae, are associated with increased risk of development of proximal ASD. PJK, a more severe form of proximal ASD, appears to have a strong relationship with ACR. Paper 17: Oblique Lateral Interbody Fusion at L5-S1: Feasibility, Surgical Approach Window, Incision Line, and Influencing Factors Jacob Razzouk - School of Medicine, Loma Linda University; Shaurya Mehta - University of California, Riverside; Gideon Harianj a- School of Medicine, Loma Linda University; Omar Ramos - Department of Orthopaedic Surgery, Loma Linda University; Nathaniel Wycliffe - Department of Radiology, Loma Linda University; Olumide Danisa - Department of Orthopaedic Surgery, Loma Linda University; Wayne Cheng - Division of Orthopaedic Surgery, Jerry L. Pettis Memorial Veterans Hospital Introduction: Oblique lateral interbody fusion at L5-S1 (OLIF51) carries significant approach-related complications. Providing a robust anatomic mapping of the OLIF51 approach may help to inform preoperative decision making and mitigate intraoperative complications. Aims/Objectives: The primary aim of this study was to describe the feasibility, surgical approach window (SAW), and incision line (IL) for OLIF51 using computed tomography (CT). A secondary aim was to identify associations among approach characteristics, and demographic and anthropometric factors. Methods: We performed a radiographic study of 50 male and 50 female subjects who received abdominal CT imaging. SAW was measured as the distance from the midline to medial border of the iliac vessel. IL was measured at the skin surface corresponding to the distance between the center of the disc space and SAW lateral margin. OLIF51 feasibility was defined as the existence of at least a 1 cm SAW without retraction of soft tissues. The intraclass correlation coefficient (ICC) two- way mixed model on absolute agreement was used to analyze interrater reliability. Differences between sexes were analyzed using independent sample t-tests. Differences between left- and right-sided measurements were analyzed using paired sample t-tests and one-way analysis of variance (ANOVA). Results: For the left side, the OLIF51 SAW and IL were 12.1±4.6 and 175.1±55.3 mm. For the right side, these measures were 10.0±4.3 and 185.0±52.5 mm. For the left versus right side, OLIF51 was not feasible 53% versus 67% of the time (p<0.001). ICC was .879 with a 95% CI of .852-.888. Differences in rate of feasibility, and SAW and IL sizes were CONCURRENT SESSION 4: FREE PAPERS 13–2417 Please Click Here to VIEW Presenter Disclosures not observed based on sex. Correlations of .648 (p<0.001) and .656 (p<0.001) were observed between weight and IL on the left and right sides, respectively. Conclusion: This is the first study to describe the bilateral feasibility, surgical approach window, and incision line for OLIF51. Left-sided OLIF51 allows for a larger approach window compared to the right side. Paper 18: Patient-centered Outcomes Following Prone Lateral Single-Position Approach to Same-Day Circumferential Spine Surgery Peter Passias; Tyler Williamson; Oscar Krol; Rachel Joujon-Roche; Bailey Imbo; Peter Tretiakov; Jamshaid M. Mir; Stephane Owusu-Sarprong; Jordan Lebovic; Ekamjeet Dhillon; Kimberly McFarland; Pooja Dave; Claudia Bennett-Caso; Dean Chou; Paul Park; Praveen Mummaneni; Justin S. Smith; Shaleen Vira; Bassel Diebo Introduction: Prone-lateral (PL) single positioning has recently gained popularity in spine surgery due to lower blood loss and operative time, but has yet to be examined for other notable outcomes, including realignment and patient-reported measures. Objectives: Evaluate surgical characteristics and postoperative 2-year results of the prone lateral circumferential approach to spinal fusion Study Design/Setting: Retrospective study Methods: We included circumferential spine fusion patients with minimum one-year follow-up. Patients were stratified into two groups based on undergoing PL approach versus same-day staged (Staged). Means comparison tests identified differences in baseline parameters. Multivariable logistic regression, controlling for age, levels fused, and Charlson Comorbidity Index (CCI) was used to determine the influence of approach on complication rates, radiographic and patient- reported outcomes up to two years. Results: 122 patients were included. 72 (59%) same- day staged and 50 (41%) PL. PL patients were older with lower BMI (both p.2). PL procedures demonstrated better correction in both PT (4.0 vs. -0.2,p=0.033 and PI-LL (-3.7 vs. 3.1,p=0.012). PL procedures were more likely to improve in GAP relative pelvic version (OR: 2.3,[1.5-8.8];p=0.003]. PL patients suffered fewer complications during the perioperative period and greater improvement in NRS-Back (-6.0 vs. -3.3,p=0.031), with fewer reoperations (0.0% vs. 4.8%,p=0.040) by two years. Conclusions: Patients undergoing prone lateral single position procedures received less invasive procedures with better correction of pelvic compensation, as well as earlier discharge. The prone lateral cohort also demonstrated greater clinical improvement and lower rate of reoperations by two years following spinal corrective surgery. Paper 19: Twenty-four Month Radiographic and Clinical Outcomes in Subjects with Risk Factors for Non-union that Underwent Single Level or Multi-level Lumbar Fusion with a Cellular Bone Allograft. Pierce D. Nunley; Daniel Park, MD - Beaumont Health System; Joshua Wind Introduction: Cellular Bone Allograft (CBA) contains the osteogenic, osteoinductive, and osteoconductive elements essential for bone healing in patients at a high risk for nonunion. There are limited prospective lumbar fusion studies to assess the safety and efficacy of CBA as an adjunct to fusion in patients with one or more risk factors for non-union. Objectives: A prospective, multicenter clinical study (NCT 02969616) was performed using Trinity ELITE CBA, to assess fusion and disease-specific disability in subjects undergoing single or multi-level lumbar arthrodesis for degenerative lumbar spinal disease. Study subjects were assessed to identify all risk factors (e.g., high BMI, nicotine use, osteoporosis, multi-level disease, etc.), which complicates postoperative bone healing. Methods: This final analysis includes 221 subjects at 12-months and 199 subjects at 24-months. Radiographic fusion was determined by independent review, characterizing angular and translational motion (< 3° and < 3mm, respectively) from flexion/extension X-rays, and the presence of bridging bone across the endplates or transverse processes (stand-alone PLF) on thin-cut CT scans. Results: The mean (± SD) age of the study cohort was 58.8 ± 12.5 years, 63% (n=173) were female, and the mean BMI was 30.7 ± 6.4. Subjects with risk factors for non-union included current nicotine users (18%, n=50), diabetics (19%, n=52), those with multi-level disc disease (25%, n=71), and those with osteoporosis (8%, n=21). Mean ODI significantly improved by 22.1 (p< 0.001) and 22.7 (p< 0.001) points from baseline at 12 and 24-months, respectively. Back pain scores decreased significantly from baseline at 12 months (39.0 points; p < 0.001) and 24 months (55.1 points; p < 0.001). Leg pain scores decreased by 45.4 points at 12 months (p < 0.001) and 64.1 points at 24 months (p < 0.001). CONCURRENT SESSION 4: FREE PAPERS 13–2418 Abstracts Fusion success rates were 91.4% (n=221) at 12-months and 91.9% (n=199) at 24-months. Fusion success for single and multi-level disease at 24-months was 91.6% (n=144) and 92.7% (n=55), respectively. Fusion success at 24-months for patients with BMI≥30 was 95.0% (n=101), nicotine users was 94.1% (n=34), diabetics was 89.7% (n=39), osteoporosis was 90.0% (n=20), and age 65+ was 91.2% (n=80). The fusion success rate for patients with 2 or more risk factors was 93.9% (n=99). A single adverse event was deemed related to the study device. Conclusions: Patients at risk for nonunion demonstrated a high rate of successful fusion and significant improvement in pain and disability at 12 and 24 months when undergoing lumbar fusion with CBA. Paper 20: Does Peri-Operative PTH Analogues in Osteoporotic Patients Help Increase Bone Density, and Decrease Mechanical Complications — Minimum 2-year Radiological Study Measuring Hounsfield Units Neel Anand - Cedars Sinai Medical Center; David Gendelberg - University of California San Francisco - Orthopaedic Trauma Institute; Anita Anand - Cedars Sinai Medical Center; Bardia Khandehroo - New York Medical College; Jose Jimenez Almonte; Andrew Chung; Babak Khandehroo - Cedars Sinai Medical Center; Sheila Kahwaty - Cedars Sinai Medical Center Introduction: Osteoporosis is common amongst elderly patients undergoing adult spinal deformity correction. Low bone density increases risk of fracture and mechanical hardware failure. The use of PTH analogues (Teriparatide) reduces complications due to osteoporosis. We conducted this study to evaluate the bone density and mechanical complication in patients with osteoporosis who took PTH analogues in conjunction with minimally invasive surgical correction for adult spinal deformity. Aim/Objectives: If patients are on PTH analogues for at least one year in conjunction with surgery, their lumbar spine bone density will improve. Materials and Methods: A prospectively collected data registry of 254 patients who underwent CMIS correction of ASD (Cobb angle>20 or SVA>50mm or (PI-LL)>10) from Jan 2011 to Jan 2020 was analyzed. Patients who were placed on PTH analogues for one year in conjunction with surgery were included for the study. 47 patients were identified. 41 patients who had pre-op and two-year post-operative CT scans for review of the Hounsfield units in the lumbar spine were included for this study. Hounsfield units were measured on L1-L3 Levels for all patients before and after surgery on pre-op and post-op CT scans. Results: Mean age of patients was 70 (52-84, SD 7). Mean follow-up was 66 (24-132, SD 33). The mean pre-op Hounsfield units of L1: 96 (33-234, SD 55), L2: 138 (32-249, SD 57), and L3: 151 (52-396, SD 85) significantly improved to L1: 185 (42- 380, SD 102), L2: 169 (64-314, SD 74), and L3: 182 (62-420, SD 95) at the 2-year post-op CT scans (p< 0.05). There was no screw loosening or screw pull out. Out of 8 patients with PJK criteria, only 2 patients underwent revision surgery (PJF 4.8%). Both these patients hadn’t completed their Teriparatide treatment: one patient only took Teriparatide for 3 months (PJK at 2-year post-op), and the other one took it only for 1 month (PJK at 1-year post-op). Only 5 patients (12%) did not show any increase in Hounsfield units in their pre-op density lumbar vertebrae after completing their PTH analogous course. Conclusion: The incidence of Teriparatide failing to increase bone density in our series was low at 12% (n=5). This study shows that Teriparatide is a useful tool in increasing bone density and decreasing mechanical complications when used in conjunction with surgery. Paper 21:Radiological and Clinical Outcomes Comparing 2-level MIS Lateral and MIS Transforaminal Lumbar Interbody Fusion in Degenerative Lumbar Spinal Stenosis Elliot Y. Chong; Reuben Soh - Singapore General Hospital; Don Koh; lenice Tan; Christoph Chong; Jiang Lei - Singapore General Hospital; Guo Chang Min; Lenice Tan Yue Tong Introduction: Both MIS LLIF and MIS TLIF are good options with comparable outcomes in single level comparison studies. There is, however, a lack of high-quality multi-level studies comparing both techniques. Objectives: To compare early postoperative radiological and clinical outcomes between 2-level minimally invasive (MIS) trans-psoas lateral lumbar interbody fusion (LLIF) and MIS transforaminal lumbar interbody fusion (TLIF) in the treatment of degenerative lumbar spinal stenosis. Methods: The study involved retrospective analysis of prospectively collected data from a single institution. The patient sample included 53 consecutive patients undergoing 2-level lumbar interbody fusion from L3-L5 for CONCURRENT SESSION 4: FREE PAPERS 13–2419 Please Click Here to VIEW Presenter Disclosures degenerative lumbar spinal stenosis from 2010 to 2018, with 24 undergoing 2-level LLIF and 29 undergoing 2-level TLIF. Demographics, comorbidities, and diagnoses between the two groups were comparable at baseline. Clinical outcomes, including perioperative data and complications, were obtained from medical records; patient reported outcomes (ODI, VAS for back and leg pain, SF-36 physical) were collected by trained personnel not directly involved in the study. For radiological outcomes, preoperative, postoperative, and 2-year postoperative lumbar spine radiographs were obtained in the neutral standing position. Fisher’s exact and independent T test were used to compare outcomes between the groups, and paired testing was used to compare different time points within groups. Results: Operative time and length of stay were similar between LLIF and TLIF (272.8±82.4 vs. 256.1±59.4 minutes; 5.5±2.8 vs. 4.7±3.3 days, p>0.05), whereas blood loss was significantly lower for LLIF (229.0±125.6 vs. 302.4±97.1mls, p=0.026). Neurological deficits were more common in LLIF than TLIF (9 vs. 3, p=0.025), whereas persistent deficits were rare for both (1 vs. 1, p=1). For both groups, all patient reported outcomes (VAS back pain, VAS leg pain, ODI, SF-36 physical) improved from preoperative to 2-year postoperative (p< 0.05), with LLIF and TLIF groups showing no significant differences in extent of improvement for any outcome. LLIF demonstrated superior restoration of disc height (L3- L4: 4.1±2.4 vs. 1.2±1.9mm, p< 0.001; L4-L5: 4.6±2.4 vs. 0.8±2.8mm, p< 0.001), foraminal height (L3-L4: 3.5±3.6 vs. 1.0±3.6mm, p=0.014; L4-L5: 3.0±3.5 vs. -0.1±4.4mm, p=0.0080), segmental lordosis (4.1±6.4 vs. -2.1±8.1°, p=0.005), lumbar lordosis (4.1±7.0 vs. -2.3±12.6°, p=0.026), and pelvic incidence-lumbar lordosis mismatch (-4.1±7.0 vs. 2.3±12.6°, p=0.019) at 2-year follow-up. Conclusion: The superior radiological outcomes demonstrated by 2-level trans-psoas LLIF did not translate into any difference in clinical outcomes compared to 2-level TLIF at the 2-year follow-up, suggesting both approaches are reasonable options for 2-level lumbar interbody fusion in degenerative lumbar spinal stenosis. Paper 22: A Retrospective Review of 110 Prone Lateral Lumbar Interbody Fusion Cases: A Single Surgeon Experience Ashish Patel - Duly Health and Care; Michael Rogers - Duly Health and Care; Eshan Doshi Introduction: Lateral lumbar interbody fusion (LLIF) allows for indirect decompression of central and foraminal stenosis, restoration of lordosis, and anterior fusion during surgical treatment of lumbar degenerative pathologies. When performed in the prone position (p-LLIF), there is a substantial improvement in time under anesthesia and cost efficiency from avoiding the flip from the traditional lateral decubitus to the prone position for decompression/osteotomy or placement of screws. We performed a retrospective look at our data and report complications. Aims/Objectives: The objective of this analysis is to report on our experience with prone lateral surgeries and perioperative complications. Methods: A retrospective chart review was conducted including intraoperative and perioperative data from patients who underwent p-LLIF from May 2019 to December 2021. Results: Our experience included a total of 208 interbody levels in 110 patients with an average age of 66.4 years. There were 65 single-level (60%), 21 two-level (18%), 20 three-level (17%), and 4 four-level (4%) surgeries performed. Eighty-one patients (73%) underwent a prone extreme lateral interbody fusion (p-XLIF) inclusive of the L4-L5 level. Two corpectomies and three anterior column reconstructions were performed. One hundred six patients had concomitant posterior work completed. The average surgical time for a single-level surgery was 72mins (min-max 51-105), with an average length of hospital stay of 1.1days (min-max 0-5). There were 2 cases of an unintentional anterior longitudinal ligament (ALL) rupture requiring interbody with plate fixation and 3 cases of femoral nerve palsy, 2 of which recovered fully at 6weeks, and a single case that improved to 4/5 at one-year post-op. There was 1 case of revision for implant malposition impinging on the contralateral foramen. There were no cases of vascular, bowel, or complete spinal cord/root/plexus injury. Conclusion: Our single surgeon experience data demonstrates the utilization of the p-LLIF technique in treating single and multilevel degenerative disease of the lumbar spine. In addition, our data demonstrates length of hospital stay and complication profile like that of a traditional LLIF performed in the lateral decubitus position. Further long-term studies are required to understand the complete utility of this approach CONCURRENT SESSION 4: FREE PAPERS 13–24Next >