ONLINE PROGRAM BOOKABSTRACTSJOINTLY PROVIDED BY:Caesars Palace MERIN Lab Las Vegas, NVAnnual Forum ’18SEPTEMBER 6–8, 2018Las Vegas, Nevada | September 6–8, 2018 ANNUAL FORUM ’182ABSTRACTSBest Paper Award Finalist Free Paper #1: A Clinical Study to Evaluate Static vs. Expandable Lateral Lumbar Interbody Fusion Devices: With One-Year Follow-upRichard Frisch, MD1; Ingrid Y. Luna, MS1; Daina Brooks, BS2; Gita Joshua, MA2; and Charles Ledonio, MD2Southeastern Spine Institute, Mt Pleasant, SC1 and Globus Medical, Inc., Audubon, PA2Introduction: Static interbody spacers have long been considered the gold standard for treating patients with degenerative disorders of the spine. However, minimally invasive (MIS) lateral lumbar interbody fusion (LLIF) procedures utilizing static spacers may require excessive trailing and forceful impaction, which may lead to iatrogentic endplate disruption, excessive neural retraction, and implant subsidence. The in situ expansion capability offered by expandable interbody spacers facilitates insertion to reduce endplate damage and optimize endplate contact. Aims/Objectives: This clinical study sought to compare radiologic and clinical outcomes of static and expandable interbody spacers following MIS LLIF and to report device-related complications including implant subsidence. Methods: This study included 64 patients with degenerative disc disease who underwent MIS LLIF at 1-2 contiguous level/s using a polyether-ether-ketone static or a titanium expandable intervertebral spacer. 32 (41 levels) were treated with a static spacer and 32 (42 levels) patients with an expandable spacer. All procedures were combined with supplemental transpedicular posterior stabilization. Analyses were based on the comparison of perioperative outcomes to radiological and clinical metrics. Results: Mean patient age was 65.8±9.7years (63% female). No significant differences were observed between static and expandable groups in operative time (70±38.1min, 78±48min), estimated blood loss (52±86.2cc, 46±543cc), or length of hospital stay (2.2±1.4days, 2.3±1.2days) (P>0.05). Mean visual analog scale pain, Oswestry Disability Index, and RAND 36-item Health Survey scores improved significantly from preoperative to 12-month follow-up in both groups (P<0.05). Intervertebral disc and neuroforaminal heights increased significantly within each group from preoperative to 12-month follow-up (p<0.01) but were not different between groups (p>0.05). Segmental lordosis increased significantly in the expandable group (14.0° ± 7.9° preoperatively to 16.4° ± 8.8° at 12 months) (p=0.01) but did not increase significantly in the static group (p=0.40). Spacer subsidence was reported in 32.4% of static and 9.8% of expandable interbody spacer levels (p<0.01). Conclusions: LLIF using expandable interbody spacers resulted in clinical outcomes similar to those of static spacers; however, the expandable group experienced a significantly greater increase in segmental lordosis and a significantly lower subsidence rate than the static group.Disclosures:R. Frisch: B; Globus Medical. F; Globus Medical. D. Brooks: E; Globus Medical. G. Joshua: E; Globus Medical. C. Ledonio: E; Globus Medical.Free Paper #2: Static vs. Expandable Interbody Devices in Minimally Invasive Transforaminal Lumbar Interbody Fusion: Comparison of Radiographic and Functional OutcomesBenjamin Khechen, BA; Brittany Haws, MD; Dil Patel, BS; Mundeep Bawa; Harmeet Bawa; Jordan Guntin, BS; Kaitlyn Cardinal, BS; Andrew Block, BS; and Kern Singh, MDRush, Chicago, ILIntroduction: Limited studies have analyzed the differences in radiographic and patient reported outcomes (PROs) between expandable and static interbody devices. Aims/Objectives: This study aims to evaluate differences in radiographic parameters and PROs following single-level minimally invasive transforaminal lumbar interbody fusion (MIS TLIF) between static and expandable interbody devices. Methods: Patients that underwent primary, single-level MIS TLIF between 2014-2017 were retrospectively identified. Only patients that had completed at least six months of postoperative follow-up were included. Radiographic measurements including lumbar lordosis (LL), segmental lordosis (SL), disc height (DH) and foraminal height (FH) were performed on lateral radiographs before and after MIS TLIF with a static or expandable articulating interbody device. Radiographic outcomes and PROs were compared using paired and unpaired Student’s t-test. SESSION 2A: DEGENERATIVE & LATERAL FREE PAPERSLas Vegas, Nevada | September 6–8, 2018 ANNUAL FORUM ’183ABSTRACTSResults: 60 patients undergoing MIS TLIF were included, with 30 patients receiving expandable interbody devices and 30 patients receiving static interbody devices. Both static and expandable device cohorts demonstrated significant increases in DH, FH, and LL. Additionally, patients receiving an expandable device demonstrated a significant increase in SL. When comparing improvements in radiographic measures, the expandable device cohort exhibited significantly greater improvement in DH and FH at final follow-up. When examining patient outcomes, both surgical cohorts experienced significant improvements in ODI, and VAS back and leg at 6-months postoperatively. Conclusions: Undergoing MIS TLIF with an expandable interbody device led to a greater increase of DH than with a static interbody device. Patients reported significant improvements in PROs following MIS TLIF in both expandable and static interbody device cohorts. However, no differences in improvement were demonstrated between surgical cohorts. Although use of expandable interbody device led to greater increases in DH, this may not correlate with superior patient outcomes. As such, patients undergoing MIS TLIF can expect similar improvements in PROs, whether receiving a static or expandable interbody device.Disclosures:B. Khechen: None. B. Haws: None. D. Patel: None. M. Bawa: None. H. Bawa: None. J. Guntin: None. K. Cardinal: None. A. Block: None. K. Singh: A; CSRS Resident Grant. B; DePuy, Zimmer, Stryker, CSRS, ISASS, AAOS, SRS, Vertebral Column - ISASS. D; Avaz Surgical, LLC, Vital 5, LLC. F; Zimmer, Stryker, Pioneer, Lippincott Williams & Wilkins, Thieme, Jaypee Publishing, Slack Publishing.Free Paper #3: Immediate Restoration of Lordosis in Single-level Minimally Invasive Transforaminal Lumbar Interbody Fusion (MI-TLIF): A Comparison of Expandable and Static Interbody CagesAvani Vaishnav, MBBS1; Philip Saville, MD1; Steven McAnany, MD1; Roger Härtl, MD2; Sertac Kirnaz, MD2; Rodrigo Navarro-Ramirez, MD, MSc2; Catherine Gang, MPH1; and Sheeraz Qureshi, MD, MBA1Hospital for Special Surgery, New York, NY1 and Weill Cornell Medicine–New York Presbyterian Hospital, New York, NY2Introduction: Minimally invasive (MIS) techniques are becoming popular in spine surgery because they are associated with reduced morbidity. However, a common concern with MIS techniques is the failure to adequately restore lordosis. Aims/Objectives: To compare lordosis generated with non-articulating expandable cages and static cages and determine if intra-operative cage-positioning affects radiographic parameters. Methods: Upright lateral radiographs of patients undergoing single-level MIS-TLIF with non-articulating expandable or static interbody cages were reviewed. Segmental lordosis (SL), regional lordosis (RL) and Posterior Disc Height (PDH) were measured pre- and post-operatively. Distance from anterior edge of vertebral body to the front of the cage was measured. Based on pre-operative SL, patients were divided into: low-lordosis (<15°), moderate-lordosis (15-25°) and high-lordosis (>25°). Mann Whitney u-test was performed to compare radiographic parameters between static and expandable cages. Linear regressions were conducted to assess the effect of pre-operative SL on post-operative SL, and the effect of cage-position on post-operative SL and PDH. Multivariate regressions were conducted with SL and PDH as dependent variables. Results: A total of 171 patients, 60 in the expandable cohort and 111 in the static cohort, were included. In the expandable group, in patients with low lordosis (n=29) SL increased (10.5° to 13.7°, p=0.01), while RL was unchanged (48°). In patients with moderate lordosis (n=21) SL (18.3° to 20.2, p=0.34) and RL (57° to 52°, p=0.07) were unchanged. In patients with high lordosis (n=10) SL decreased (29.5° to 25.3°, p<0.03), while RL was unchanged (59 to 57°, p=0.49). In the static group, in patients with low lordosis (n=28) SL increased (10.6° to 13.7°, p<0.05), while RL was unchanged (47° to 48°). In the moderate lordosis group (n=48) SL (19.1° to 17.5°, p=0.08) and RL (56° to 55°, p=0.47) were unchanged. In patients with high lordosis (n=38) SL (29.5 to 25.3°, p=0.02) and RL (62° to 58°, p=0.002) decreased. When the static and expandable group were compared, there were no significant differences. PDH increased in both groups (Static: 5.9 to 8.2mm, Expandable: 3.6 to 7.5mm). Linear regressions showed that pre-operative SL moderately correlated with post-operative SL (R2=0.41, p<0.00001), but cage-position was not correlated with post-operative SL (R2=0.02) or PDH (R2=0.03). Multivariate regression for post-operative SL confirmed that pre-operative SL was predictive of post-operative SL, as was RL to a lesser extent; cage-position, cage-type, and pre-operative PDH were not. Multivariate regression for post-operative SESSION 2A: DEGENERATIVE & LATERAL FREE PAPERSLas Vegas, Nevada | September 6–8, 2018 ANNUAL FORUM ’184ABSTRACTSSESSION 2A: DEGENERATIVE & LATERAL FREE PAPERSPDH showed that cage-type, pre-operative PDH and pre-operative SL were related, but cage-position was not. Conclusions: Pre-operative SL was predictive of post-operative SL. There was no difference in lordosis generated by non-articulating expandable cages and static cages. Expandable cages resulted in a significantly improved PDH but showed no benefit in SL.Disclosures:A. Vaishnav: None. P. Saville: None. S. McAnany: None. R. Härtl: B; Brainlab, DePuy-Synthes, Ulrich. S. Kirnaz: None. R. Navarro-Ramirez: None. C. Gang: None. S. Qureshi: B; Zimmer-Biomet, Stryker Spine, Globus Medical Inc. D; Avaz Surgical. F; RTI, Zimmer-Biomet, Stryker Spine.Free Paper #4: Do Expandable Cages Lead to a Higher Incidence of Subsidence? Two-year Follow-up of Lateral Lumbar Interbody FusionsDan Cohen, MD1; Joseph O’Brien, MD2; William Tally, MD3; Thomas Lee, MD4; Torrey Shirk, BA5; Gita Joshua, MA5; and Charles Ledonio5Spine Care Institute of Miami Beach, Miami Beach, FL1; The George Washington University School of Medicine & Health Sciences, Washington, DC2; Athens Orthopedic Clinic, Athens, GA3; Spinemore Surgical Associates, P.C., St Louis, MO4; and Globus Medical, Inc., Audubon, PA5Introduction: Minimally invasive lateral lumbar interbody fusion (LLIF) using expandable spacers has been shown to have similar positive outcomes compared to static spacers, but with lower subsidence. Expandable interbody devices are designed to be inserted at a reduced disc height and expanded to optimal height within the disc space. Aims/Objectives: The current study seeks to investigate the outcomes of patients treated with LLIF using an expandable interbody device, and to assess subsidence. Methods: Data were prospectively collected for 27 patients (at 29 operative levels) undergoing LLIF with an expandable interbody fusion implant. Patients returned for follow-up visits through 24 months. Clinical and radiographic data were collected and analyzed. Complications were recorded. Results: Mean age of the patients was 58.7 years, and 63% of patients were female. Twenty-two patients (77.8%) underwent 1-level surgery, and the remaining 6 patients (22.2%) underwent 2-level surgery. Oswestry Disability Index scores decreased significantly from preoperative scores at all time points. Disc height and neuroforaminal height increased significantly over preoperative heights at 6 weeks, and remained significantly increased at 24 months. At 24 months, 96.4% of patients were determined to have achieved fusion. Radiographs showed no subsidence, migration, or collapse of the implant in any patient. Conclusions: The use of an expandable interbody device in an LLIF procedure led to positive clinical outcomes, and increased disc heights and neuroforaminal heights by 24 months. No observed subsidence in the current study lends support to the expectation that expandable implants help reduce endplate disruption.Disclosures:D. Cohen: B; Globus Medical. F; Globus Medical. J. O’Brien: B; Globus Medical, Medtronic, Stryker. D; K2M, RTI, ISD. F; Globus Medical, Nuvasive, RTI. W. Tally: F; Globus Medical. T. Lee: None. T. Shirk: E; Globus Medical. G. Joshua: E; Globus Medical. C. Ledonio: E; Globus Medical.Best Paper Award FinalistFree Paper #5: Minimally Invasive Spine Surgery through Lumbar Decompression: Patient-Reported Outcomes from more than 9,000 CasesStefan Prada, MD1; Michael Weiss, DO1; Stephen Songhurst, BS1; Chip Wade, PhD2; and Reginald Davis, MD1Laser Spine Institute, Tampa, FL1 and Auburn University, Auburn, AL2Introduction: Open lumbar laminectomy has long been the treatment of choice for lumbar stenosis and other degenerative conditions. However, subsequent lumbar instability from open approaches has turned the attention to minimally invasive surgery (MIS) techniques. Recently, studies have demonstrated similar outcomes for minimally invasive decompression (MID) techniques when compared to open approaches. Las Vegas, Nevada | September 6–8, 2018 ANNUAL FORUM ’185ABSTRACTSSESSION 2A: DEGENERATIVE & LATERAL FREE PAPERSAims/Objectives: The purpose of our study was to evaluate one of the largest MIS-MID cohorts for safety and efficacy in a free-standing ambulatory surgery center (ASC). Methods: From February 2012 to December 2017, 9,188 lumbar MIS-MID surgical cases were evaluated. Inclusion criteria required cases to have patient-reported outcomes (PROs) data at preoperative and one postoperative interval. The PROs were collected through surveys while the operative variables were extracted from electronic health records. The PROs survey includes a visual analog scale (VAS), Oswestry Disability Index (ODI) and a return to work (RTW) item. Operative variables include estimated blood loss (EBL), length of surgery (LOS) and intraoperative complications. Results: Significant improvements (p < .001) in both pain and disability from preoperative to postoperative were observed. The postoperative follow-up ranged from 90 to 2,021 days, resulting in a mean of 238.21 days (SD = 238.05). Mean VAS values improved from 6.21 to 3.65 from preoperative to postoperative, respectively. Similarly, mean ODI values improved from 46.14 to 27.32 from preoperative to postoperative, respectively. The RTW analysis, which included 6,569 cases, revealed that 86.07% of the sample reported returning to their usual occupation at the postoperative follow-up interval. Operative results extracted from about 30% of the sample demonstrated mean EBL and LOS values of 59.53 mL and 68.88 minutes, respectively. Only 57 (1.89%) of the 3,017 cases evaluated for intraoperative complications were marked, of which 52 were dura leaks. A sub-analysis of 497 MIS-MID cases was performed to demonstrate improvements from preoperative to postoperative along a continuum. The inclusion criteria required all cases to have pain and disability data at preoperative, as well as three-, six-, 12- and 24-months postoperative. Mean VAS values were 5.88, 2.97, 2.79, 2.83 and 3.11 with respect to preoperative, three-, six-, 12- and 24-months postoperative. Similarly, mean ODI values were 43.11, 21.08, 20.45, 20.57 and 23.01 with respect to preoperative, three-, six-, 12- and 24-months postoperative. Conclusions: We conclude that MIS-MID surgeries can be performed safely and effectively in a free-standing ASC. Additionally, MIS-MID surgeries result in few complications, minimal blood loss, short operative times and positive outcomes.Disclosures:S. Prada: None. M. Weiss: None. S. Songhurst: None. C. Wade: None. R. Davis: None.Free Paper #6: Minimally Invasive Transforaminal Lumbar Interbody Fusion (MI-TLIF) vs. Minimally Invasive Lateral Lumbar Interbody Fusion (MI-LLIF): A Comparison of Immediate Post-Operative Outcomes for the Assessment of DecompressionSheeraz Qureshi, MD, MBA; Avani Vaishnav, MBBS; Catherine Himo Gang, MPH; Steven McAnany, MD; and Todd Albert, MDHospital for Special Surgery, New York, NYIntroduction: Surgical decompression to relieve pressure on neural structures can be performed by direct decompression (i.e. resection of impinging tissue), indirect decompression (i.e. distraction between vertebrae to increase the space), or a combination of the two. Aims/Objectives: To compare outcomes of surgical procedures that involve direct and indirect decompression (i.e. MI-TLIF) to procedures that involve only indirect decompression (i.e. MI-LLIF), to assess if the additional direct decompression results in better outcomes. Methods: Clinical outcomes (length of stay, post-operative pain, in-hospital complications, need for additional direct decompression surgery), and patient-reported outcomes (PROs including ODI, VAS and SF-12) in patients undergoing MI-TLIF and MI-LLIF were compared using chi-square test for categorical and student’s t-test for continuous variables. Mixed ANOVA was used to assess if the change in PROs from pre-operatively to post-operatively was different between MI-TLIF and MI-LLIF. Results: Of the 72 patients, 49 had MI-TLIF and 23 had MI-LLIF. There were no differences in age (58.88+12.31vs 61.77+8.84 years, p=0.255), sex (36.7%vs 54.2% males, p=0.157) or BMI (27.57+7.31vs 27.44+3.99 kg/m2, p=0.933). The number of levels operated was greater in the MI-LLIF group compared to the MI-TLIF group (1.43vs 1.12, p=0.047), with almost 90% of MI-TLIFs being 1-level procedures and none 3-level. In contrast, 65% of MI-LLIFs were 1-level, 26% 2-level and 8.7% 3-level procedures. The level(s) operated were different, with over 60% of MI-TLIFs at L4-L5 and 34.5% at L5-S1, compared to 51.6% of MI-LLIFs at L3-L4, 24.2% at each L2-L3 and L4-L5, and none at L5-S1. There was no difference in procedural time (105.31+29.56 minutes in MI-TLIF vs 126.00+85.63 in MI-LLIF, p=0.281), length of stay (45.39+32.99 hours in MI-TLIF vs 35.64+23.43 in MI-LLIF, p=0.216), post-operative pain (5.42+1.94 Las Vegas, Nevada | September 6–8, 2018 ANNUAL FORUM ’186ABSTRACTSSESSION 2A: DEGENERATIVE & LATERAL FREE PAPERSin MI-TLIF vs 5.65+2.37 in MI-LLIF, p=0.180), or in-hospital complications (10.2% in MI-TLIF vs 4.3% in MI-LLIF, p=0.384). Additionally, no patient in the MI-LLIF group required subsequent direct decompression surgery due to persistence of symptoms. ODI, VAS leg, SF-12 MHS, SF-12 PHS and PROMIS-PF did not differ between the groups preoperatively or at 2-weeks. VAS back pain was worse in the MI-LLIF group at both time-points (p=0.020). Additionally, the change in PROs did not differ between the groups (ODI: p=0.970, VAS back: p=0.982, VAS leg: p=0.667, SF-12 PHS: p=0.848, SF-12 MHS: p=0.495, PROMIS-PF: p=0.744). Conclusions: There was no difference in outcomes between those who underwent MI-LLIF (indirect decompression), and those who underwent MI-TLIF (indirect and direct decompression). Thus, in an appropriately selected patient, indirect decompression can provide results that are comparable to direct compression. Underlying pathology, operative level and goals of the surgery should be kept in mind when selecting the procedure.Disclosures:S. Qureshi: B; Zimmer-Biomet, Stryker Spine, Globus Medical Inc. D; Avaz Surgical. F; RTI, Zimmer-Biomet, Stryker Spine. A. Vaishnav: None. C. Gang: None. S. McAnany: None. T. Albert: B; DePuy, a Johnson & Johnson Company, Nuvasive. D; ASIP, Biometrix, Breakaway Imaging, Crosstree, Facetlink, Gentis, InVivo Therapeutics, Invuity, Paradigm Spine, PMIG, Spinicity, Vertech. F; Biomet, DePuy, a Johnson & Johnson Company, Jaypee Publishing, Saunders/Mosby-Elsevier, Thieme.Free Paper #7: Employment is Associated with Superior Patient Reported Outcomes following Minimally Invasive Lumbar Spondylolisthesis Surgery: An Analysis of the Quality Outcomes DatabaseAndrew Chan, MD1; Erica Bisson, MD, MPH2; Mohamad Bydon, MD3; Steven Glassman, MD4; Kevin Foley, MD5; Eric Potts, MD6; Christopher Shaffrey, MD7; Mark Shaffrey, MD7; Domagoj Coric, MD8; John Knightly, MD9; Paul Park, MD10; Michael Wang, MD11; Kai-Ming Fu, MD, PhD12; Jonathan Slotkin, MD13; Anthony Asher, MD8; Panagiotis Kerezoudis, MD3; Regis Haid, MD14; and Praveen Mummaneni, MD1University of California, San Francisco, CA1; University of Utah, Salt Lake City, UT2; Mayo Clinic, Rochester, MN3; Norton Leatherman Spine Center, Louisville, KY4; Semmes-Murphey Neurologic and Spine Institute, Memphis, TN5; Goodman Campbell Brain and Spine, Indianapolis, IN6; University of Virginia, Charlottesville, VA7; Carolina Neurosurgery & Spine Associates, Charlotte, NC8; Atlantic Neurosurgical Specialists, Morristown, NJ9; University of Michigan, Ann Arbor, MI10; University of Miami, Miami, FL11; Weill Cornell Medical Center, New York, NY12; Geisinger Health System, Danville, PA13; and Atlanta Brain and Spine Care, Atlanta, GA14Introduction: The factors driving the best outcomes following minimally invasive surgery (MIS) for grade 1 lumbar spondylolisthesis are not clearly elucidated. Aims/Objectives: This study investigates the factors that drive the best 12-month patient reported outcomes (PRO) following MIS lumbar spondylolisthesis surgery. Methods: 797 patients from twelve high-enrolling sites participating in the Quality Outcomes Database (QOD) Spondylolisthesis Module underwent surgery for degenerative grade 1 lumbar spondylolisthesis. Surgeries were classified as MIS if any of the following were involved: MIS laminectomy, MIS pedicle screws, MIS interbody grafts, cortical screws, or percutaneous screws. Baseline and 12-month follow-up parameters were collected. PROs included the numeric rating scale (NRS) Back Pain, NRS Leg Pain, Oswestry Disability Index (ODI), and EuroQoL-5D (EQ-5D) Questionnaire. Multivariate models were constructed which included adjustment for patient characteristics (age, gender, body mass index, comorbidities, smoking status), presentation characteristics (dominant presenting symptoms, motor deficit on presentation, ambulation status, symptom duration), surgical variables (surgical approach, fusion versus nonfusion surgery), socioeconomic characteristics (ethnicity, education, employment status, insurance type), and baseline PRO values. Results: 318 (39.9%) patients underwent surgery via MIS techniques. The mean age of the MIS cohort was 63.9 ± 11.4 years and consisted of 180 (56.6%) women. At presentation, 136 (42.8%) were employed (employed and/or employed on leave). In multivariate analyses, employment status remained the sole significant predictor of superior MIS outcomes across the four PROs at 12 months (ODI OR=0.004 95% CI [0.0001-0.35], p=0.02, NRS back pain OR=0.45 [0.24-0.86], p=0.02, NRS leg pain OR=0.40 [0.21-0.78], p=0.01, and EQ-5D OR=1.06 [1.02-1.11], p=0.01). Aside from baseline PRO values, additional 12-month MIS predictors of (1) ODI included 4 years Las Vegas, Nevada | September 6–8, 2018 ANNUAL FORUM ’187ABSTRACTSof education or greater (OR=0.01 [0.0002-0.82], p=0.04), (2) NRS Back Pain included fusion surgery (OR=0.45 [0.20-0.996], p=0.049), (3) NRS Leg Pain included baseline anxiety (OR=3.20 [1.07-9.51], p=0.04), independent ambulation at baseline (OR=0.38 [0.16-0.92], p=0.03), and (4) EQ-5D included baseline depression (OR=0.93 [0.87-0.99], p=0.02), independent ambulation (OR=1.08 [1.02-1.15], p=0.01), and presence of a motor deficit at presentation (OR=0.95 [0.90-0.99], p=0.02). The multivariate analyses were repeated with the 479 (60.1%) open surgical patients, which did not identify employment as a significant predictor of ODI, NRS back pain, NRS leg pain, or EQ-5D (all p>0.05). Conclusions: Multiple factors affect 12-month outcomes following lumbar spondylolisthesis surgery. For MIS, but not open spondylolisthesis surgery, employment status remained the sole significant predictor of best outcomes across the four domains of disease-specific disability, back pain, leg pain, and health-related quality of life.Disclosures:A. Chan: None. E. Bisson: B; nView. M. Bydon: None. S. Glassman: B; Medtronic. F; Medtronic. K. Foley: B; Medtronic. D; Medtronic; Nuvasive; Spine Wave. F; Medtronic. E. Potts: None. C. Shaffrey: B; Nuvasive; Zimmer Biomet. D; Nuvasive. F; Nuvasive; Medtronic; Zimmer Biomet. M. Shaffrey: None. D. Coric: B; Spine Wave; Stryker; Medtronic; Premia Spine. D; Spine Wave; Premia Spine; Spinal Kinetics. J. Knightly: None. P. Park: B; Globus; Nuvasive; Allosource; Medtronic. F; Globus. M. Wang: A; Department of Defense. B; DePuy Synthes; JoiMax USA; K2M; Aesculap Spine; Vallum. D; Spinicity. F; Depuy Synthes. K. Fu: B; SI-BONE. J. Slotkin: B; Stryker. A. Asher: None. P. Kerezoudis: None. R. Haid: B; Nuvasive. D; Spine Universe. F; Nuvasive; Medtronic. P. Mummaneni: A; AOSpine. B; DePuy Synthes; Globus; Stryker; Spineart. D; Spinicity; ISD. F; DePuy Spine, Thieme Publishers, and Springer Publishers.Free Paper #8: Pre-operative Opioid Use Associated with Worsened Outcomes in Patients Undergoing Stand-alone Lateral Lumbar Interbody Fusion for Degenerative Disc DiseaseDavid Salvetti, MD; Alp Ozpinar, MD; Nima Alan, MD; David Okonkwo, MD, PhD; Adam Kanter, MD; and D. Kojo HamiltonUniversity of Pittsburgh, Pittsburgh, PAIntroduction: Outcomes in spine surgery may benefit from pre-operative optimization of medical comorbidities, nutritional status, and weight management. With increasing concern over prescription opioid dependence for chronic conditions such as back pain, it is critical to understand how this may affect spine surgery outcomes. Aims/Objectives: The aim of this study is to evaluate whether post-operative outcomes are linked to pre-operative opioid dependence following lateral lumbar interbody fusion (LLIF). Methods: A consecutive series of 48 patients from a single institution undergoing LLIF for degenerative spondylosis were identified and retrospectively analyzed. Patients were categorized according to the presence or absence of prescribed pre-operative opioid use of greater than 6 months duration. Basic demographic data was collected as well as pre- and post-operative outcome measures including Oswestry Disability Index (ODI), Visual Analog Scale (VAS), and Short Form 36 Physical and Mental Summary Scores (SF36-PCS, SF36-MCS). Statistical comparisons between groups were performed using an analysis of variance (ANOVA). Results: Of the 48 patients, (23 male, 25 female) mean age was 48.2 ± 14.6 years. The mean clinical follow up period was 14.1 months with the mean number of levels operated upon being 2 (range 1-4). Twenty-two patients (45%) were prescribed preoperative opioids for >6 months with a mean oral morphine equivalent of 14.3±11.4mg/day. Mean preoperative ODI was 46.1±12.9 (non-opioid 43.8±11.8, opioid 48.9±14, p=0.198). Mean postoperative ODI was 28.7±16.4 (non opioid 22.2±14.7, opioid 36.5±15.6, p=.003). There was a trend in the change in postoperative from preoperative ODI, with the non-opioid group showing a greater magnitude of improvement (-21.6±17.6 vs. -12.4±17.4, p=0.089). Mean preoperative VAS was 6.6±2.0 (non-opioid 6.5±1.9, opioid 6.7±1.0, p=0.802), and mean postoperative VAS was 4.1±2.3 (non-opioid 3.2±2.1, opioid 4.1±2.1, p=0.005). There was a statistically significant change in postoperative from preoperative VAS, with the non-opioid group showing a greater subjective decrease in pain (-3.3±2.4, -1.6±2.6, p=0.032). The differences from pre and post-operative SF36-PCS and SF36-MCS scores were not significantly different overall or by opioid use group. Conclusions: Preoperative opioid use correlated with less benefit in health-related quality of metrics following LLIF for degenerative spondylosis. Further study is required to identify whether strategies to wean preoperative opioids could negate this association.SESSION 2A: DEGENERATIVE & LATERAL FREE PAPERSLas Vegas, Nevada | September 6–8, 2018 ANNUAL FORUM ’188ABSTRACTSDisclosures:D. Salvetti: None. A. Ozpinar: None. N. Alan: None. D. Okonkwo: B; Nuvasive, Zimmer-Biomet. F; Nuvasive, Zimmer-Biomet. A. Kanter: B; Nuvasive, Zimmer-Biomet. F; Nuvasive, Zimmer-Biomet. D. Hamilton: None.Free Paper #9: Systematic Review of Facet Tropism as it Relates to Degenerative Disc Disease in the Lumbar Spine: The Overlooked Synovial JointFabio Pencle, MBBS1; Moawiah Mustafa2; Luai Mustafa2; Omar Viqar2; Zaid Sheikh3; and Kingsley Chin, MD1LESS Institute, Hollywood, FL1; Florida International University, Miami, FL2; and Florida International University, Miami, FL3Introduction: Lower back pain affects 28% of adults and is the fifth most common reason for visiting a physician in the United States. Degenerative disc disease, degenerative spondylolisthesis, arthritis, and facet arthrosis are major contributory pathologies for lower back pain. The facet joints, also known as the zygapophyseal joints, are located in the posterior aspect of the vertebral column and are the only true synovial joints between the vertebrae in humans. Aims/Objectives: Our goal is to study the facet processes in particular because of scarce information noted in the literature. The question remains if facet tropism is the root underlying cause leading to these major contributing pathologies or merely a symptom of another etiology.Methods: According to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, a systematic review of PubMed, Scopus, Cochrane database and EMBASE was performed on February 6th, 2018. The employed search strategy including all Medical Subject Heading (MeSH) terms consisted of the following: (“Facet Tropism”) AND (“Degenerative disc disease”). Results: A total of 8813 unique articles were identified from all four databases through the systematic search. The title and abstract were screened for meeting the inclusion criteria. A total of 30 articles were found with a combination of keywords (“Facet Tropism”) AND (“Degenerative disc disease”). Analysis of studies demonstrated that facet tropism was associated with muscular asymmetry in patients with chronic low back pain. Several key relationships have been shown across the studies. There is an increased stress transmission, stress concentration across the facet joint and disc. This could cause spondylosis, spondylolisthesis at proximal adjacent segment as well as lumbar degenerative disc disease. One study noted more FT in people with progressive facet arthrosis (PFA) vs. without PFA. The data presented in this study suggests that facet tropism is correlated significantly with facet joint degeneration in segments which are involved in frequent segmental motion. Mean facet tropism showed no significant difference between patients with far lateral and posterolateral lumbar disk herniations, this contradicts the previous article. Conclusions: This study aimed to review the available literature to assess facet joint tropism in lumbar degenerative disc disease. The literature and analysis demonstrate a definite correlation between both and may be a major factor for the treatment in lower back pain.Disclosures:F. Pencle: None. M. Mustafa: None. L. Mustafa: None. O. Viqar: None. Z. Sheikh: None. K. Chin: D; SpineFrontier.Free Paper #10: Influence of Lumbar Stenosis on Concomitant Sacroiliac Joint Pain: Short-Term and Preliminary Long-Term ResultsKonrad Bach, MD and Thomas Freeman, MDUSF, Tampa, FLIntroduction: As many as 30% of chronic back pain sufferers complain of sacroiliac joint (SIJ) pain, and minimally invasive surgical techniques have made surgical treatment of the SIJ increasingly effective and attractive for surgeon and patient alike. Many patients have both claudication symptoms due to lumbar stenosis as well as concomitant SIJ pain. Aims/Objectives: We hypothesize that this SIJ pain is secondary to walking with a flexed posture to alleviate claudication symptoms. If true, we hypothesize that this “secondary SIJ pain” will spontaneously improve after successful lumbar laminectomy or laminectomy and fusion when patients resume walking upright, obviating the need for surgical treatment of the sacroiliac joint. SESSION 2A: DEGENERATIVE & LATERAL FREE PAPERSLas Vegas, Nevada | September 6–8, 2018 ANNUAL FORUM ’189ABSTRACTSMethods: A retrospective review of charts from 01/01/2014 through the present was performed to identify sequential cases of adults 35 years of age or older with concomitant surgical spinal stenosis with neurogenic claudication as well as SIJ pain. SIJ pain was diagnoses clinically +/- confirmatory injection (≥ 50% improvement in SIJ pain). A 10-point VAS was used to assess SIJ pain preoperatively, at three months postoperatively, and at most recent follow up. Results: 17 contiguous patients (8 female) met entry criteria. 10 were treated with decompression alone, 7 with decompression and fusion. Mean SIJ VAS score improved in the decompression alone group by 8.0±2.4 (8.9±1.7 - 0.9±2.2; p<0.0005). Mean SIJ VAS score improved in the decompression and fusion group by 8.9±2.0 (9.4±1.0 - 0.6±1.1; p<0.0005). There was no significant difference in VAS change when comparing those with SIJ pain diagnosed clinically and confirmed by injection (n=7) vs. those diagnosed clinically alone. Conclusions: Sacroiliac joint pain shows rapid and dramatic improvement following lumbar laminectomy alone in patients with lumbar stenosis with claudication. The addition of a fusion also leads to a similar magnitude of improvement in SIJ pain. These results suggest that SIJ pain in patients with stenosis and claudication is secondary to walking in a flexed position, corrected rapidly after successful spinal decompression. While MIS techniques have improved SIJ surgery, in patients with concomitant stenosis with neurogenic claudication, it may not be necessary to operate on the SIJ altogether. Further research is needed to determine if other sagittal deformity corrections alleviate concomitant SIJ pain.Disclosures:K. Bach: None. T. Freeman: None.Free Paper #11: Anterior Column Release (ACR) during Lateral Interbody Fusion for Hyperlordotic Segmental CorrectionLarry Khoo, MD1; Roya Gheissari, MS2; and Charlie Loeb2Spine Clinic of Los Angeles, Los Angeles, CA1 and Los Angeles, CA2Introduction: Evidence to maximize segmental lumbar lordosis (LL) during spinal fusion to optimize LL and Pelvic Parameters continues to grow steadily. ACR represents the next evolution of traditional lateral lumbar interbody fusion (LLIF) techniques. Aims/Objectives: We sought to assess the safety, efficacy, and morbidity of the ACR technique in LLIF Methods: In a prospective study, 72 patients with segmental listhesis and sagittal imbalance were treated via LLIF during which ACR and implantation of a hyperlordotic fusion cage were completed. Same stage posterior arthrodesis and fixation were also done. Peri-operative data, radiographic and clinical outcomes were collected. Results: Preoperative data: mean age 67, BMI 28.5, CMI 1.6, T-scores -0.6, ODI 44, VAS leg 8.5, VAS back 9.75. OR data: Surgical time- 65 minutes (LLIF) 53 min (PSF/decompression), ebl total 75cc, LOS 2.5 days, Complications (major 1.5%, minor 8.3%)- 1 vascular, 4 transient psoas praxia (avg 2.5 wks), 1 wound dehiscence, 1 abdominal hernia, transfusions 1. Clinical Outcomes: 12 mo ODI change -23, VAS back -6.5, VAS leg -7.5. 53 cases used fixed cages of 20 degrees (22 avg) lordosis. 19 cases utilized an expandable and variable angle titanium cage (20-30 degree final). Radiographic Outcomes: Lordotic correction +19.5 immediate postop (16.5 fixed, 22.3 expandable), 18.2 deg at 6 months, 17.8 deg correction at 12 mos, Pelvic tilts improved at -9.5 deg postop, -13.2 at 6 months and -14.1 at 12 mos. Rigid fusion with 1 yr dynamic xrays and CT scan was observed in 67/72 (93%) with 5/72 demonstrating stable pseudoarthrosis. Conclusions: Instrumented ACR with or without expandable interbody implants represents a ready, far less-invasive and morbid alternative to traditional osteotomy deformity correction techniques.Disclosures:L. Khoo: None. R. Gheissari: None. C. Loeb: None.Free Paper #12: Minimally Invasive Multilevel Oblique Lumbar Interbody Fusion (OLIF): An Anatomical Single Position Approach for CMIS Correction of Adult Spinal Deformity (ASD)Neel Anand, MD; Edward Nomoto, MD; Christopher Kong, MD; Babak Khandehroo, MD; and Sheila Kahwaty, PA-CCedars Sinai Medical Center, Los Angeles, CAIntroduction: Lateral Transpsoas Interbody fusion surgery has been an effective adjunct to Circumferential MIS treatment of ASD. Recently an oblique lateral approach allows SESSION 2A: DEGENERATIVE & LATERAL FREE PAPERSNext >