Annual Forum SEPTEMBER 29–OCTOBER 1, 2022 | THE BELLAGIO | LAS VEGAS, NV ONLINE PROGRAM BOOK Abstracts2 Table of Contents CONCURRENT SESSION 3: FREE PAPERS Paper 1: Comparison of Reimbursement Rates Between Anterior Lumbar Interbody Fusion and Lumbar Disc Replacement from 2007 to 2022 Paper 2: Intraoperative Methylprednisolone Reduced ODI but Not VAS: Results from the ROIDs Trial Paper 3: Association Between Muscle Health and Patient-Reported Outcomes After Lumbar Microdiscectomy Paper 4: What Factors Drive Delayed Deterioration of Oswestry Disability Index Following Minimally Invasive Surgery for Adult Spinal Deformity? Paper 5: Pre-operative Predictors of Distal Failure Following Minimally Invasive Deformity Surgery with Sparing of the Lumbosacral Junction Paper 6: Outcomes and Complications After Anterior Lumbar Interbody Fusion with Percutaneous Pedicle Screws for Grade II/III Isthmic Spondylolisthesis Paper 7: The Incidence of Complications and Neurological Deficits in Split Tubular, Endoscopic, and Robotic-assisted Endoscopic TLIFs: There Is a Difference Paper 8: Two-Year Outcomes of Full- endoscopic Versus Open Discectomy for Sciatica Paper 9: Robotics Reduces Radiation Exposure in Minimally Invasive Lumbar Fusion Compared To Navigation Paper 10: Incidence of Radiographic and Clinically Significant Pneumohemothorax after Minimally Invasive Lateral Retropleural Approach for Thoracic Disc Herniation: Consecutive Case Series Paper 11: Early Compensatory Segmental Angle Changes at L3-L4 and L4-L5 Following a L5-S1 Anterior Versus Transforaminal Lumbar Interbody Fusion 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 CONCURRENT SESSION 4: FREE PAPERS Paper 13: Single Position Transpsoas Corpectomy and Posterior Instrumentation in the Thoracolumbar Spine for Different Clinical Scenarios Paper 14: Cervical Disc Arthroplasty and Range of Motion at 7-years: Impact on Adjacent Level Degeneration Paper 15: Multimodal Analgesic Protocol for Cervical Disc Replacement in the Ambulatory Setting: Clinical Case Series Paper 16: Proximal Adjacent Segment Disease Over Ten Years After Lateral Lumbar Interbody Fusion3 Please Click Here to VIEW Presenter Disclosures Paper 17: Oblique Lateral Interbody Fusion at L5-S1: Feasibility, Surgical Approach Window, Incision Line, and Influencing Factors Paper 18: Patient-centered Outcomes Following Prone Lateral Single-Position Approach to Same-Day Circumferential Spine 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. 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 Paper 21: Radiological and Clinical Outcomes Comparing 2-level MIS Lateral and MIS Transforaminal 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 Paper 23: Vascular and Visceral Complications Following Prone Transpsoas Lateral Lumbar Interbody Fusion: A Comparative Study to a Historical Survey Study on Standard Lateral Lumbar Interbody Fusion Paper 24: Early Clinical Outcomes of Prone Transpsoas Lumbar Interbody Fusion Technique CONCURRENT SESSION 5: YOUNG SURGEON FREE PAPERS Paper 25: Long-term Durability of Stand-alone Lateral Lumbar Interbody Fusion Paper 26: Lateral Single Position Anterior- Posterior Lumbar Fusion Outperforms Conventional Anterior-Posterior Lumbar Fusion with Patient Repositioning at 2-year Minimum Follow-Up Paper 27: Implant Size and Position Affects Patient Reported Outcomes After Lateral Lumbar Interbody Fusion Paper 28: High-level Evidence of Posterior Minimally Invasive Scoliosis Surgery Versus the Standard Posterior Approach for the Management of Adolescent Idiopathic Scoliosis Paper 29: Comparing 12-month Quality of Life, Work Status, and Disability Outcomes Between Decompression & Dynamic Sagittal Tether Stabilization vs. Transforaminal Lumbar Interbody Fusion for the Management of Lumbar Degenerative Spondylolisthesis. Interim Results of an FDA IDE Study Paper 30: Are 2-year Reoperation Rates Different for Circumferential Minimally Invasive Surgery (cMIS) vs. Open ASD Surgery? A Propensity Matched Cohort Study Using a Prospective ASD Database4 Table of Contents Paper 31: Comparing Long-Term Deformity Correction and Other Outcomes Between Single Level Circumferential XLIF and MI-TLIF: A Retrospective Review With 5-Year Minimum Follow Up Paper 32: A Powerful Tool to Create Lordosis, Anterior Column Release Can Come with Its Own Complications — A Case Series Paper 33: The Anatomical Positioning of Retroperitoneal Organs in Single-position Prone Lateral Lumbar Surgery Paper 34: VR Simulation Module for Spinal Instrumentation Demonstrates Improved Procedural Confidence and Performance Dose Response in Neurosurgical Trainees: Pilot Study Paper 35: The Safety and Efficacy of Erector Spinae Plane Blocks in Minimally Invasive Spine Surgery: Modulation of Pain Scores, Opioid Requirements, and Adverse Events Paper 36: Impact of Pandemic-induced Staff Shortages and Utilization of Immediate Use Surgical Sterilization on Surgical Site Infection After Spine Surgery SESSION 12: FREE PAPERS—LIGHTING ROUND Paper 37: A Single Center, Randomized Control Trial of IV Versus Oral Acetaminophen Perioperative to Instrumented Lumbar Fusion Paper 38: Surgeon-placed Erector Spine Paravertebral Block and Continuous Bupivacaine Infusion for Pain Control After Lumbar fusion Paper 39: Resolution of Back Pain Following Minimally Invasive Laminectomy Paper 40: Impact of Facet Replacement vs. TLIF in a Prospective Randomized FDA Study on ODI and Post-Operative Opioid Utilization Among Subjects at 24 Months Paper 41: Hardware Failure Over Ten Years After 574 Levels of Lateral Lumbar Interbody Fusion Paper 42: Biomechanical Comparison of Unilateral and Bilateral Pedicle Screw Fixation After Multilevel Lumbar Lateral Interbody Fusion Utilizing 26 mm Cages Paper 43: Biomechanical Comparison of Stability and Anterior Column Load Sharing: Transfacet-Intralaminar Cortical Fixation versus Traditional Pedicle Screw Instrumentation After Lateral Interbody Fusion Paper 44: A Retrospective Study of Lumbar Circumferential Fusion: Interlaminar Fusion Stabilization versus Pedicle Screw Instrumentation Paper 45: The Efficiency and Accuracy of the Robotic Assistance in Pedicle Screw Placement Paper 46: Objective and Subjective Validations of a Novel Spinal Guidance System for Pedicle Screw Placement Using Augmented Reality and Artificial Intelligence Paper 47: Minimally Invasive Percutaneous Screw Placement in Thoracic and Lumbar Spine with Optical Skin Marker Based Augmented Reality Navigation: Results from a Prospective Study5 Please Click Here to VIEW Presenter Disclosures Paper 48: Location Variance of the Great Vessels During Positioning Changes While Undergoing DLIF Paper 49: Do the 5-Year Outcomes for Minimally Invasive and Open Transforaminal Lumbar Interbody Fusion for Grade 1 Degenerative Lumbar Spondylolisthesis Differ? Paper 50: Decompression and Dynamic Sagittal Tether for Degenerative Spondylolisthesis: 24-month Pain, Disability and Reoperation Outcomes in 222 Patients from an FDA IDE Study Paper 51: Evaluating the Incidence of Subsequent Surgical Decompression Following Minimally Invasive Approaches to Treat Symptomatic Lumbar Spinal Stenosis: A Retrospective Database Review Paper 52: Biomechanical Analysis of Expandable Interbody Cage Stiffness, Force Exertion, and Subsidence in the Setting of Spondylolisthesis Paper 53: Clinical and Radiographic Outcomes of Late-onset Cage Subsidence After Minimally Invasive Lateral Lumbar Interbody Fusion Paper 54: Minimally Invasive Lumbar Decompression Versus Minimally Invasive Transforaminal Lumbar Interbody Fusion for Treatment of Low-Grade Lumbar Degenerative Spondylolisthesis Paper 55: Early Outcomes of Multilevel ACDF with Segmental Plate Fixation Paper 56: Impact of Age Within Younger Populations on Outcomes Following Cervical Surgery in the Ambulatory Setting Paper 57: Anterior Vertebral Body Tethering Has Reduced Pain and Improved Function for the First 6 Weeks After Surgery Compared to Fusion Paper 58: Clinical and Radiographic Results After Proximal Lumbar Anterior Column Realignment in Patients with Adult Spinal Deformity Paper 59: Does the Severity of Facet Arthropathy Limit the Sagittal Re-alignment in Circumferential Minimally Invasive Surgical (CMIS) Correction of Adult Spinal Deformity (ASD)? Paper 60: Circumferential Minimally-Invasive Adult Spinal Deformity Surgery Provides Incremental Benefit for Increasingly Frail Patients Paper 61: Sacroiliac Joint Fusion Navigation: How Accurate is Pin Placement? Paper 62: Shorter Length of Stay and Increased Return to Work with Cervical Disc Arthroplasty Versus Anterior Cervical Discectomy and Fusion Paper 63: Timing of Nerve Transfer Surgery for C5 Palsy: Does Recovery at 6 Months Predict Final Recovery? Paper 64: Incidence of Major Complications in Lateral Lumbar Interbody Fusion (LLIF) Performed via the Prone Transpsoas (PTP) Technique: A Survey of the Complete Early Experience6 Table of Contents Paper 65: Clinical Outcomes of the Prone Transpsoas Lateral Lumbar Interbody Fusion for Degenerative Lumbar Spine Disease: A Multicentre Study Paper 66: Complications Associated with Single Position Prone Lateral Lumbar Interbody Fusion: a Systematic Review and Meta-analysis Paper 67: Minimally Invasive Lateral Lumbar Interbody Fusion for Clinical Adjacent Segment Pathology — A Comparative Study with Conventional Posterior Lumbar Interbody Fusion Paper 68: Comparison of Pressure on the Soft Tissue Using 2 Different Lateral Retractors: Sweeping in Muscular Plane vs. Traditional Tubular Dilation. Paper 69: Risk Factors Analysis for Inferior Clinical Outcome and Recurrence After Full- endoscopic Interlaminar Discectomy (FEID) for Lumbar Disc Herniation; A Prospective Observational Study7 Please Click Here to VIEW Presenter Disclosures Paper 1: Comparison of Reimbursement Rates Between Anterior Lumbar Interbody Fusion and Lumbar Disc Replacement from 2007 to 2022 Vincent Federico; Athan Zavras - Rush University Medical Center; Alexander J. Butler, MD - Lenox Hill Hospital; Michael Nolte; Mohammed Munim; Samy Gabriel; Augustus Rush; Matthew Colman, MD - Rush University Medical Center; Frank Phillips, MD - Rush University Medical Center Introduction: Lumbar Disc Replacement (LDR) has proven to be a safe and effective treatment option for patients with degenerative disc disease (DDD) refractory to conservative management, with randomized controlled trials demonstrating noninferior to improved outcomes when compared to Anterior Lumbar Interbody Fusion (ALIF). Despite this, the utilization of LDR has been found to be decreasing over time. The reason for this continued decrease in volume is likely multifactorial. Objectives: The purpose of this study was to evaluate and compare the reimbursement trends between ALIF and LDR in the Medicare population. Methods: The Physician Fee Schedule Look-Up Tool from the Centers for Medicare and Medicaid Services (CMS) was queried using the Current Procedural Terminology (CPT) codes for ALIF (22558) and LDR (22857), and reimbursement data was extracted for years 2007 to 2022. Compound annual growth rates (CAGR) were calculated and adjustments in inflation to 2022 US Dollars (USD) were corrected for using the Consumer Price Index. Descriptive statistics and linear regression were used to evaluate trends in Medicare reimbursement rates for both nominal and inflation adjusted values. Results: Nominal reimbursement for LDR increased from $1391.74 in 2007 to $1831.18 in 2022 (31.6% increase over time). After adjusting for inflation, this resulted in a 6.8% decrease in reimbursement. ALIF experienced a 12.1% nominal increase in surgeon reimbursement, from an average of $1409.53 to $1579.42 between 2007 and 2022, respectively. However, this resulted in an inflation adjusted decrease of 20.6% over the 15-year study period. Moreover, ALIF reimbursements demonstrated a significant linear decline over time (R2 = 0.5, p = 0.002), while LDR did not (R2 = 0.03, p = 0.5). Adjusted CAGR redemonstrated this trend, with ALIF experiencing a significant linear decline over time (R2 = 0.41, p = 0.01), as compared to LDR (R2 = 0, p = 0.96). If Medicare had adjusted payments to coincide with the modest cost-of- living changes made to social security during the study period, ALIF and LDR reimbursements would be 120% and 102% of current rates, respectively. Conclusion: Both ALIF and LDR reimbursements have failed to keep up with adjustments in inflation. When compared to LDR, ALIF has undergone a significantly greater decline in adjusted reimbursement, with a nearly 21% decline over the study period. Further studies are needed to evaluate the efficacy, durability, and economic sustainability of both procedures. Paper 2: Intraoperative Methylprednisolone Reduced ODI but Not VAS: Results from the ROIDs Trial TJ Florence, MD, PhD - UCLA Neurosurgery; Daniel C. Lu, MD, PhD - UCLA Neurosurgery Introduction: Epidural methylprednisolone instillation (EMI) is a commonly used intraoperative adjunct during decompressive surgery. However, there is little data supporting its use. Existing literature show equivocal effects in reducing postoperative pain; moreover, there is reasonable concern that direct steroid instillation could increase the risk of wound breakdown and postoperative infection. Here we present early results from the prospective Randomized Operative Instillation of Depomedrol (ROIDs) trial. Aims/Objectives: To evaluate the utility of this technique, we performed a large multi-year single-center, single surgeon prospective randomized study. Methods: A total of 485 patients undergoing elective minimally invasive decompression were randomized in singly blinded fashion to steroid instillation or saline irrigation. Patients were followed for an average of 5.17 years. Patient demographics and treatment history were collected. Changes in symptomatic severity as measured by Owestry Disability Index (ODI) and pain Visual Analog Scale (VAS) were taken as primary outcomes. Secondary outcomes included ER visits, readmissions, and opioid use. Results: Methylprednisolone was associated with a significant reduction (16.7 vs. 21.0, p=0.04) in ODI at two weeks versus placebo. This effect was strongest among patients with high preoperative ODI. There was no significant reduction in VAS. The cohorts demonstrated identical opiate and ESI utilization. There was no difference in ER visits or readmissions. Methylprednisolone was associated with an increased risk of reoperation (7.9 vs. 3.7%, p = 0.049) during the observation period. There was no difference in perioperative complications. CONCURRENT SESSION 3: FREE PAPERS 1–12 8 Abstracts Conclusions: These data demonstrate that EMI is effective in reducing ODI but not VAS scores in patients with significant preoperative disability. Using VAS as a solitary measure may conflate preoperative symptoms with expected post-surgical pain. This may explain conflicting results from prior studies. Current efforts are focused on studying the duration of this effect and underlying cause of the apparent elevated risk of reoperation. Paper 3: Association Between Muscle Health and Patient-Reported Outcomes After Lumbar Microdiscectomy Junho Song - Hospital for Special Surgery; Kasra Araghi; Marcel Dupont; Pratyush Shahi; Patawut Bovonratwet; Daniel Shinn; Sidhant Dalal; Evan Sheha; James Dowdell; Sohrab Virk, MD - Department of Orthopaedic Surgery, North Shore University Hospital-Long Island Jewish Medical Center; Sravisht Iyer; Sheeraz Qureshi Introduction: Poor muscle health has been implicated as a source of back pain among patients with lumbar spine pathology. Recently, a novel magnetic resonance imaging (MRI)-based lumbar muscle health grade was shown to correlate with health-related quality of life scores. However, the impact of muscle health on postoperative functional outcomes following spine surgery remains to be investigated. Aims/Objectives: To determine whether muscle health grade measured by preoperative psoas and paralumbar muscle cross-sectional areas impact the achievement of minimal clinically important difference (MCID) following lumbar microdiscectomy. Methods: Consecutive patients who underwent 1-level lumbar microdiscectomy in a single institution between 2017-2021 were included. Two previously validated methods for muscle health grading were applied. Axial T2 MRI were analyzed for muscle measurements. The psoas-based method utilized the normalized total psoas area (NTPA), which is the psoas cross-sectional area divided by the square of patient height (mm2/m2). The paralumbar-based method incorporated the paralumbar cross-sectional area normalized by body mass index (PL-CSA/BMI) and Goutallier classification. Prospectively collected PROMs were analyzed at various postoperative timepoints up to 2 years. The rate of and time to MCID achievement were compared among the cohorts. Bivariate analyses were performed to assess for correlations between psoas/paralumbar cross-sectional areas and change in PROM scores from baseline. Results: The total cohort included 163 patients with minimum follow-up of 6 months and mean follow-up of 16.5 months. 40 patients (24.5%) were categorized into the low NTPA group, and 55 patients (33.7%)were categorized into the poor paralumbar muscle group. There were no differences in rates of MCID achievement for any PROMs between low vs. high NTPA groups or between poor vs. good paralumbar groups. Low NTPA was associated with longer time to MCID achievement for ODI, VAS back, VAS leg, and SF-12 MCS. Poor paralumbar muscle health was associated with longer time to MCID achievement for VAS back, VAS leg, and SF- 12 PCS. NTPA negatively correlated with change in VAS back (6-week, 12-week)and VAS leg (6-month). PL-CSA/BMI positively correlated with change in PROMIS-PF at 3 months follow-up. Conclusions: Among patients undergoing lumbar microdiscectomy, patients with worse muscle health grades achieved MCID at similar rates but required longer time to achieve MCID. Lower NTPA was weakly correlated with larger improvements in pain scores. PL-CSA/BMI positively correlated with change in PROMIS-PF. Our findings suggest that with regards to functional outcomes, patients with worse muscle health may take longer to recuperate postoperatively compared to those with better muscle health. Paper 4: What Factors Drive Delayed Deterioration of Oswestry Disability Index Following Minimally Invasive Surgery for Adult Spinal Deformity? Andrew K. Chan, MD - Columbia University/NewYork-Presbyterian; Dean Chou; Robert K. Eastlack; Richard Fessler; Khoi D. Than; Kai-Ming Fu; Paul Park; Michael Y. Wang, MD, FACS; Adam S.; David O. Okonkwo - University of Pittsburgh; Pierce D. Nunley; Neel Anand; Juan Uribe; Jay Turner; Gregory Mundis; Peter Passias; Shay Bess - Denver International Spine Center, Presbyterian St. Luke’s Medical Center; Christopher Shaffrey; Saman Shabani; Vivian Le, MPH - UCSF; Praveen Mummaneni Introduction: The factors associated with delayed deterioration following circumferential minimally invasive surgery (cMIS) for adult spinal deformity (ASD) are not completely defined. Aims/Objectives: To identify specific factors that lead to delayed deterioration after cMIS for ASD. Methods: This was a retrospective analysis of a prospective multicenter ASD database. Patients undergoing cMIS for ASD with 2-year follow-up with one of the following were included: maximum CC≥20°, SVA>5 cm, PI-LL≥10°, CONCURRENT SESSION 3: FREE PAPERS 1–12 9 Please Click Here to VIEW Presenter Disclosures CONCURRENT SESSION 3: FREE PAPERS 1–12 or PT>20°. Pre- and postoperative characteristics were compared for cohorts with the same or improved ODI (unchanged) or worse ODI (worse) between 1 (1Y) and 2 years (2Y) postoperatively. Clinically significant ODI worsening was defined as ΔODI >2.5 standard deviations. Outcome measures included 2-year ODI, NRS Back Pain, NRS Leg Pain, EQ-5D, EQ-5D VAS, SF-36 PCS, SF-36 MCS, and SRS-22r Total Score. Radiographic parameters included CVA, maximum coronal Cobb angle (CC), fractional curve Cobb angle (FC), SVA, PI- LL, and PT. 2-year complications were compared, including overall, major, minor, and reoperations. Results: Of 85 patients prospectively enrolled, 67 met inclusion criteria: 36 patients (53.7%) were Unchanged and 31 patients (46.3%) were Worse—only 2 (3.0%) had clinically significant ODI worsening. The two cohorts did not differ for clinical and surgical characteristics, including proportion of surgeries including S1 and the ilium (p>0.05). Despite starting with similar 1Y clinical outcomes (p>0.05 for NRS Back Pain, NRS Leg Pain, EQ-5D, EQ-5D VAS, SF-36 PCS/MCS, SRS- 22r) and superior 1YODI (22.7 vs. 30.9, p=0.027), Worse ultimately had higher 2YODI (38.0 vs. 21.0, p<0.001). Starting at 6 weeks, CVA was greater for Worse (36.3 vs. 22.8 mm, p=0.010), and this relationship was sustained at 1Y (33.8 vs. 21.6 mm, p=0.013) and 2Y (30.0 vs. 20.4 mm, p=0.038). This was associated with a 2Y elevation in FC for Worse (9.6 vs. 5.5°, p=0.023). There was no association between delayed deterioration and SVA, PI-LL, PT, and max CC (p>0.05). Reoperation and complication rates did not differ for the groups (p>0.05). Conclusions: Following cMIS for ASD, postoperative coronal malalignment at 6 weeks is associated with delayed deterioration in ODI between 1 and 2 years. An association between sagittal parameters and delayed deterioration was not observed. Preoperative disability, pain, quality of life, radiographic parameters, and postoperative complication occurrence—including reoperations—were not associated with delayed deterioration. Paper 5: Pre-operative Predictors of Distal Failure Following Minimally Invasive Deformity Surgery with Sparing of the Lumbosacral Junction Joseph Didomenico - Barrow Neurological Institute; James Zhou - Barrow Neurological Institute; S. Harrison Farber, MD - Barrow Neurological Institute; Joseph Abbatematteo; Timothy Gooldy; Juan Uribe; Jay Turner Introduction: Multilevel minimally invasive (MIS) lumbar deformity correction warrants consideration of whether to include the lumbosacral junction. In circumventing fixation across the L5-S1 segment, lumbar range of motion is preserved. However, the added stress of a long fused construct can lead to an increased risk for distal degeneration at the lumbosacral junction. This analysis seeks to elucidate the radiologic factors that may predict distal failure following L5-S1 sparing multilevel MIS lateral interbody fusions. Methods: A single-center retrospective analysis of L5-S1 sparing MIS lumbar lateral interbody fusions (LLIF) was completed. Patients without a minimum of 6 months follow- up were excluded. All patients were treated by L1-L5 or L2- L5 LLIFs with or without posterior segmental fixation. Pre- operative Cobb angles of the fractional curve, anterior and posterior disc height, and a disc height index (DHI) at L5-S1 were measured. Grades were assigned for the severity of facet arthropathy and disc degeneration by the Weishaupt and Pfirrmann classifications, respectively. These parameters were assessed for change at post-operative intervals until last follow-up or distal failure. Results: A cohort of 29 patients were included. The mean age of the population was 70 years old. 5 patients (17%) required extension across the L5-S1 segment for distal failure, at an average of 23 months from the initial surgery (SD = 13.45 months). Mean pre-operative posterior L5-S1 disc height was decreased for this subset (4.77mm vs. 5.99mm, p= 0.012). Mean pre-operative L5-S1 DHI for patients requiring revision was decreased compared to those who did not but did not reach significance. On last follow-up, those warranting revision had a further reduction in the posterior disc height and DHI. Pre-operatively, 80% of patients requiring revision had underlying grade III disc degeneration at L5-S1, compared to 35% in the subset not revised (p= 0.030). Severity of facet arthropathy did not differ between the two groups. Conclusions: Lumbar deformity correction through an MIS LLIF approach has several benefits in the way of patient satisfaction, rate of arthrodesis, and overall morbidity. For deformities not involving the lumbosacral junction, an L5- S1 sparing procedure can preserve range of motion while greatly improving global alignment. Patient selection based on radiologic parameters is critical to reduce the likelihood for revision surgery. Characteristics of the L5-S1 disc space, namely disc height and severity of disc degeneration as determined on pre-operative MRI, may help in predicting those patients less likely to have longstanding success with preservation of the lumbosacral junction.Next >