< PreviousAbstracts AnnualForum’19 50ANNUAL FORUM ’19 | LAS VEGAS, NEVADA | OCT. 31–NOV. 2, 2019 CONCURRENT SESSION 8B: LATERAL, BIOLOGICS & HEALTHCARE ECONOMICS FREE PAPERS 24 months was more significant in the static group compared to the expandable group (p<0.05). Mean improvement in neuroforaminal height from preoperative to 6 weeks, 3, and 6 months was significantly greater in the expandable group compared to the static group (p<0.05). Subsidence was 0% in the expandable group and 18.5% in the static group. Conclusions: This study showed significant positive clinical and radiographic outcomes for patients who underwent MIS LLIF using titanium expandable interbody spacers with adjustable lordosis based on significant changes in VAS back pain scores, ODI scores, and radiographic parameters at 24-month follow- up. There was a 0% subsidence rate in the expandable group, compared to a 18.5% subsidence rate in the static group. Disclosures: Y. Li: A; Globus Medical. B; Depuy Synthes. Z. Huang: A; Globus Medical. J. Towner: None. Y. Li: A; Globus Medical. J. Riggleman: D; Globus Medical. E; Globus Medical. C. Ledonio: E; Globus Medical. Paper #64: Laterally Placed Expandable Interbody Spacers Improve Radiographic and Clinical Outcomes: A Two-Year Follow-up Study Yan Michael, MD, PhD 1 ; Zheng Huang, MD, PhD 2 ; James Towner, MD 1 ; Yan Icy Li, PhD 1 ; Samantha Greeley, BS 3 ; and Charles Ledonio, MD, CCRP 3 University of Rochester Medical Center, Rochester, NY 1 ; Guanghua Hospital, Shanghai, China 2 ; and Globus Medical, Inc., Audubon, PA 3 Introduction: Severe degenerative disc diseases necessitate surgical management with large interbody spacers to regain disc space. Static interbody spacers are the standard of care for minimally invasive lateral lumbar interbody fusion (MIS LLIF). However, using large static interbody spacers requires sacrifice of posterior stabilizing structures and aggressive endplate preparation prior to implant insertion, which may lead to subsidence, compromised stability, and adjacent segment disease. Aims/Objectives: This study describes clinical and radiographic outcomes of patients treated with expandable interbody spacers for MIS LLIF. Methods: This is a single-surgeon, retrospective IRB-exempt chart review on 22 consecutive patients who underwent MIS LLIF at 1-2 contiguous level(s) using expandable interbody spacers. Radiographic and clinical functional outcomes were collected and compared at preoperative and postoperative time points up to 24 months. Statistical results were significant if p<0.05. Results: Twenty-two consecutive patients were evaluated— average age, 57.6±11.0 years; 45.5% were female. Visual Analog Scale (VAS) back and leg pain scores decreased significantly by an average of 7.1±1.2 points at 24 months (p<0.001). Oswestry Disability Index (ODI) scores significantly decreased by a mean of 67.1±10.0 points at 24 months (p<0.001). Lumbar lordosis improved by a mean of 1.8±8.0° at 24 months. There were 28 spinal levels, with 42.9% at L3-4 and 39.3% at L4-5. Anterior, middle, and posterior disc height significantly increased at 24 months by averages of 4.7±3.6, 4.0±3.9, and 1.9±2.4 mm, respectively (p<0.001). Neuroforaminal height significantly increased at 24 months by a mean of 2.6±3.7 mm (p<0.001). Segmental lordosis significantly improved by 2.5±2.0° at 24 months (p<0.001). There was 100% fusion at all levels, with no cases of radiolucency. One incidence of subsidence (1/28, 3.6%) was reported at 24 months. There were no reported implanted-related complications, with no pseudoarthrosis and no secondary procedures. Conclusions: This study showed positive clinical and radiographic outcomes for patients who underwent MIS LLIF with expandable interbody spacers. Sagittal correction and indirect decompression were achieved and maintained up to 24-month follow-up from baseline, based on increased disc height, neuroforaminal height, and segmental lordosis. Functional clinical outcomes significantly improved based on decreased VAS pain and ODI scores at 24 months. Use of lateral expandable spacers was shown to be safe, durable, and effective for the studied patient population. Disclosures: Y. Michael: A; Globus Medical. B; Depuy Synthes. Z. Huang: A; Globus Medical. J. Towner: None. Y. Li: A; Globus Medical. S. Greeley: E; Globus Medical. C. Ledonio: E; Globus Medical. Paper #65: Determinants of Indirect Decompression in Lateral Lumbar Interbody Fusion David Xu, MD9; Jakob Godzik, MD 2 ; Corey Walker, MD 2 ; Joshua Wewel, MD 2 ; Nikolay Martirosyan, MD 2 ; James Zhou, MD 2 ; Jay Turner, MD, PhD 2 ; and Juan Uribe, MD 2 Baylor College of Medicine, Houston, TX 1 and Barrow Neurological Institute, Phoenix, AZ 2 Introduction: Lateral lumbar interbody fusion (LLIF) achieves indirect decompression of central stenosis through restoration of disc space height, augmentation of segmental lordosis, and ligamentotaxis. However, there is little understanding Abstracts AnnualForum’19 51ANNUAL FORUM ’19 | LAS VEGAS, NEVADA | OCT. 31–NOV. 2, 2019 CONCURRENT SESSION 8B: LATERAL, BIOLOGICS & HEALTHCARE ECONOMICS FREE PAPERS of anatomic or surgical factors that can affect the degree of indirect decompression and amount of segmental lordosis achieved. Aims/Objectives: The authors queried a single surgeon patient database of consecutive LLIF cases with pre- and postoperative MRI and CT-imaging to assess radiographic and clinical factors that impact the degree of indirect decompression and segmental lordosis achieved at the operative level. Methods: Inclusion criteria were patient age >18 years, and a postoperative MRI and CT-scan obtained within 48 hours after surgery. Demographic, clinical, and multiple radiographic measurements on CT and MRI were collected by the authors. The degree of indirect decompression was measured as the change in anterior-posterior (AP) diameter of the thecal sac, as well as changes in the interfacet distance measured on axial sequences. Statistical testing utilized the Kruskal-Wallis and one-way analysis of variation (ANOVA) for categorical and ordinal data, and the spearman correlation for continuous data. Results: A total of 40 patients with 72 treated disc space levels were analyzed. Based on a paired t-test, statistically significant increases in the sagittal AP thecal sac diameter (mean 2.6 mm, p<0.001), axial AP thecal sac diameter (mean 2.7 mm, p<0.001), interfacet thecal sac diameter (mean 2.5 mm, p<0.001), and segmental lordosis (mean 3.3⁰, p<0.001) occurred after surgery. On univariate analysis, the only factors that were found to correlate significantly with changes in the AP or interfacet thecal sac diameter were the baseline anterior (p=0.037) and posterior (p=0.004) disc space height, the change in the posterior disc space height after surgery (p=0.017), and the distance of the interbody away from the posterior disc space margin (p=.038). The degree of segmental lordosis was correlated to the severity of facet arthropathy ( p< 0.001) and reduction of anterolisthesis postoperatively (p<0.001). Notably, the dimensions of the implant and vacuum disc phenomenon did not impact segmental lordosis or indirect decompression Conclusions: Very few factors were found to correlate with the amount of central decompression in LLIF with the exception to the preoperative severity of disc space collapse and how posterior the implant is placed. One explanation is that even with the smallest sized implant utilized, most of the structurally achievable indirect decompression has already been maximized, suggesting a diminishing rate of return for aggressive interbody sizing Disclosures: D. Xu: None. J. Godzik: None. C. Walker: None. J. Wewel: None. N. Martirosyan: None. J. Zhou: None. J. Turner: None. J. Uribe: B; NuVasive, Misonix. D; NuVasive. F; NuVasive. Paper #66: The Role of Osteobiologics in Posterior Spinal Fusion Surgery— Do Cellular-Based Allografts Perform As Well As Autografts? Donald Kucharzyk, DO 1 and Dushan Budimir, BS 2 DK Orthopedics, Crown Point, IN 1 and The Center for Spine Minimally Invasive Surgery, Crown Point, IN 2 Introduction: Osteobiologics have seen a rise in use during spinal fusion surgeries to avoid complications associated with autografts. With this premise, various use of alternatives DBM, BMS, BMP, synthetics, allograft, and cellular-based allografts has risen as high as 95%. With the best alternative needing to possess the triad for fusion: osteogenesis, osteoinduction, and osteoconduction. Cellular-based allografts possess all 3 of these as well as contain viable mesenchymal stem cells. Aims/Objectives: A retrospective study was conducted to look at the effect of a cellular-based allograft Trinity Elite (Orthofix, Lewisville, TX) compared to the gold standard autograft (via literature comparison), as well as to Trinity Evolution (Orthofix, Lewisville, TX) was performed . Methods: A total of 150 patients who underwent lumbar fusions between 2016 to 2019 were included; a had 2-year follow-up. All the cases received Trinity Elite mixed with local autograft. All were evaluated for age, gender, height, weight, risk factors, levels fused, diagnosis, clinical presentation, bone graft volume, radiographics, outcome measurements, Minimal Clinical Importance Difference, and fusion rates. Results: The mean age of patients was 57.5 years, the male to female ratio was 1:1, mean height was 68 inches and mean weight 155 lbs. Risk factors included smoking in 68 patients, diabetes in 47, cardiovascular disease in 79, steroid dependence in 20, prior surgery in 70, and prior fusion surgery in 45. Surgical levels fused included L2-S1 in 6, L3-S1 in 28, L4-S1 in 33, L5-S1 in 66, 5 levels in 4, and 6 levels in 3. Patients were diagnosed with DDD in 125, spondylolisthesis in 100, radiculopathy in 130, spinal stenosis in 115, instability in 125, HNP in 130, facet arthropathy in 140, spondylosis in 130, and scoliosis in 25. The majority of patients (85%) reported back and leg pain, while the remainder reported back pain only (2%) and leg pain only (13%). Bone graft volume was 25 mL per level (12.5 mL per side)—15 mL allograft and 10 mL local autograft. A fusion was seen in 94.8%. Outcomes after initial surgery and 2-years follow-up included overall VAS reduction from 78.6 to 25, VAS back from 7.4 to 1.2, VAS leg: 8.0 to 0.5, ODI from 54.7 to 10.5, and Minimal Clinical Importance Difference (greater than 20 pts) 90%. Abstracts AnnualForum’19 52ANNUAL FORUM ’19 | LAS VEGAS, NEVADA | OCT. 31–NOV. 2, 2019 CONCURRENT SESSION 8B: LATERAL, BIOLOGICS & HEALTHCARE ECONOMICS FREE PAPERS Conclusions: Results revealed a fusion rate of 94.8% was achieved in this retrospective study. Compared to the literature autograft IC and local (31 studies) fusion rates were 79 % (40% to 100%) and 89% (65% to 95%) with this study showing a higher fusion rate. Comparing Trinity Elite to Trinity Evolution (the first-generation) Musante 2016 showed a fusion rate 90.7% compared to 94.8% for Trinity Elite. Based upon this study and compared to the literature for autograft, this cellular- based allograft produced comparable and higher fusion rate even in the presence of risk factors effecting fusion rates. Disclosures: D. Kucharzyk: A; RTI Medical. B; Orthofix , LifeSpine, SeaSpine, Medicrea, Sur-Gen-Tec, Precision Spine. C; Orthofix, SeaSpine, LifeSpine. F; Medicrea ,Precision Spine. D. Budimir: None. Paper #67: Titanium Implants Manufactured with Proprietary 3D-Printing Build Themes Contain Surface Features That Increase Biologic Activity Xiaoxan Xin 1 ; Kris Radcliff, MD 2 ; and David Rowe, MD 1 University of Connecticut, Farmington, CT 1 and Thomas Jefferson University-Rothman, Egg Harbor Township, NJ 2 Introduction: Biomaterials designed to mechanically support a gap within a bony structure need to be conducive for osteoprogenitor cells to firmly attach and build a matrix that will integrate with the adjacent host bone. Previous studies have demonstrated that acid etching of titanium creates a surface roughness that allows for osteoblastic differentiation. Similarly, surface features can be modified by varying build theme parameters in additive manufacturing. However, few studies exist on the biological effects of titanium surfaces generated by 3D printing processes. Aims/Objectives: The purpose of this study is to determine whether the surface of titanium structures created by proprietary electron-beam melting (EBM) build themes induces biological activity that is superior to PEEK or smooth titanium. Methods: We compared the osteogenic response of primary mouse bone marrow stromal cells (BMSCs) when plated on discs composed of 3D-printed, roughened titanium (3DPT), smooth titanium (ST), PEEK, and tissue culture plastic control (TCP). The BMSCs were derived from a dual transgenic mouse line that produced a green color at an early stage of osteogenesis (BSP- YFP) and red color with full osteocyte differentiation (DMP-RFP) allowing for real-time assessment of osteogenesis during a 21- day time course using a fluorescent microscope. Results: At day 3, 7, 14 and 21, samples were imaged for their fluorescent signal, trypsin-treated to release the cells from the discs and RNA-extracted for expression of transcripts that reflect the level of osteogenic activity. The 3DPT initiated differentiation sooner and reached a higher fluorescence intensity that TCP and ST (PEEK was not assessed due to its high autofluorescent background). The cells were firmly attached to the 3DPT relative to the other materials but the analysis of the liberated cells showed that 3DPT supported the highest percentage of BMSCs to enter the osteogenic lineage. The isolated cell analysis confirmed that the progression to full differentiation on 3DPT was equivalent to TCP and significantly better that SM and PEEK. The RNA expression was consistent with the fluorescence-based study with the markers of full differentiation (bone gamma-carboxyglutamate protein [Bglap] and PHEX gene) in the 3DPT and TCP being 10- to 100-fold higher than PEEK and ST. Conclusions: This study suggest that surface features manufactured with proprietary build themes are more biologically active than traditional smooth surfaces of titanium and PEEK. Future studies will be designed to compare different 3D-printed titanium surfaces and acid etched surfaces to ascertain if this property translates into improved integration with host bone. Disclosures: X. Xin: A; 4 Web Medical. K. Radcliff: A; 4 Web Medical, Simplify Medical, Orthofix, Biocomposites. B; Stryker K2M, 4 Web Medical, Advance Medical. D; Rothman Institute, 4 Web Medical. F; Globus Medical, Orthopedic Sciences, Innovative Spinal Devices. D. Rowe: A; 4 Web Medical. Paper #68: Cost-Effectiveness of Microdiscectomy Versus Endoscopic Discectomy for Lumbar Disc Herniation Jin-Sung Kim, MD, PhD 1 ; Kyung Chul Choi, MD, PhD 2 ; and Choon Keun Park, MD, PhD 3 Seoul St Mary's Hospital, The Catholic University of Korea, Seoul, Republc of Korea1; Leon Wiltse Memorial Hospital, Anyang, Republic of Koreaf2; and Leon Wiltse Memorial Hospital, Suwon, Republic of Korea 3 Introduction: Microdiscectomy (MD) is a standard technique for the surgical treatment of lumbar disc herniation (LDH). Endoscopic discectomy (ED) is another surgical option that has become popular owing to reports of shorter hospitalization and earlier return to work. No study has evaluated health care costs associated with lumbar discectomy techniques and compared cost-effectiveness. Abstracts AnnualForum’19 53ANNUAL FORUM ’19 | LAS VEGAS, NEVADA | OCT. 31–NOV. 2, 2019 CONCURRENT SESSION 8B: LATERAL, BIOLOGICS & HEALTHCARE ECONOMICS FREE PAPERS Aims/Objectives: To assess the cost-effectiveness of 4 surgical techniques for LDH: microdiscectomy (MD), transforaminal endoscopic lumbar discectomy (TELD), interlaminar endoscopic lumbar discectomy (IELD), and unilateral biportal endoscopic discectomy (UBED). Methods: Five hundred sixty-five patients aged 20- to 60 years who underwent either MD or ED for primary LDH using 1 of the 4 surgical techniques with at least 1-year follow-up were reviewed. Health care costs were defined as the sum of direct and indirect costs. The former included the covered and uncovered costs of the National Health Insurance from operation to 1-year follow-up; indirect costs included costs incurred by work loss. Direct and indirect costs were evaluated separately. Incremental cost-effectiveness ratio (ICER) was determined using cost/quality-adjusted life year (QALY). Health care costs and ICER were compared statistically among the 4 surgical groups. Cost-effectiveness was compared statistically between MD and ED. Results: One hundred fifty-seven patients who underwent TELD, 132 for IELD, 140 for UBED, and 136 for MD were enrolled. The direct costs of TELD, IELD, UBED, and MD were $3,452.2±1,211.5, $3,907.3±895.3, $4,049.2±1,134.6, and $4,302.1±1,028.9, respectively (p<.01). The indirect costs of TELD, IELD, UBED, and MD were $574.5±495.9, $587.8±488.3, $647.4±455.6, and $759.7±491.7, respectively (p<.01). The 1-year QALY gains were 0.208 for TELD, 0.211 for IELD, 0.194 for UBED, and 0.186 for MD. ICER (costs/QALY) was the highest for MD ($34,840.4±25,477.9, p<.01). Compared with MD, ED saved an additional net of $8,064 per QALY (p<.01). There was no significant difference in the ICERs among the three endoscopic techniques. 1-year follow-up. Disclosures: J. Kim: B; RIWOSpine, Elliquence, GS Medical, Innovasive. D; Medrics. K. Choi: None. C. Park: None. Paper #69: Combined Nucleus Pulposus Augmentation and Annulus Fibrosus Repair Prevents Intervertebral Disc Degeneration After Experimental Discectomy Sertac Kirnaz, MD; Christoph Wipplinger, MD; Stephen Sloan; Franziska Schmidt, MD; Antonella Schiavinato; Lawrence Bonassar, PhD; and Roger Hartl, MD Weill Cornell Medicine, New York, NY Introduction: Tissue-engineered approaches for the treatment of early stage intervertebral disc degeneration have shown promise in a variety of preclinical studies. None of these therapies have been approved for clinical use in part because they target only a single aspect of the intervertebral disc’s composite structure. At present, there is no reliable method to prevent intervertebral disc degeneration after herniation and subsequent discectomy. Here we demonstrate the prevention of degeneration and maintenance of mechanical function in the ovine lumbar spine after discectomy by combining strategies for nucleus pulposus augmentation using hyaluronic acid injection and repair of the annulus fibrosus using a photo-crosslinked collagen patch. Aims/Objectives: Objective of the current study is to assess the efficacy of combined annulus fibrosus (AF) using high-density collagen (HDC) geland nucleus pulposus (NP) repair using a hyaluronic acid (HA) gel in an in-vivo sheep model. Methods: We performed an anterolateral, retroperitoneal pre- psoas approach to access the intervertebral disc (IVD) L1-6 in a total of 8 skeletally mature Finn sheep. IVDs were randomized into 5 groups: intact; injured via 3x10 mm box annulotomy and removal of 200 mg of NP; injury and HDC gel patch for AF repair; injury and injection of a HA gel into the NP; and injury and HDC AF repair and NP HA replacement. At 6-weeks postoperatively, sheep were sacrificed and underwent post-mortem 3T-MRI scans as well as gross anatomical and histological evaluation. Disc height index (DHI) analysis and Pfirrmann grading (PG) were performed on each segment using MR images. Results: Intact control discs were not degenerated and had an average PG of 1, while injured, untreated discs had significant degeneration with an average PG of 3. Discs receiving the combined injection and collagen AF patch individually showed fewer signs of degeneration than injured alone, and the combined treatment resulted in the least amount of degeneration with PG not significantly different than the intact controls. DHI confirmed the trends seen in the PG, where injured discs lost 20% of the intact disc height, the individual NP and AF repairs restored 5%-10% of intact disc height, and the combined repairs preserved 90% of the intact disc height. Conclusions: PG and DHI results demonstrate that individual NP and AF repairs are able to prevent disc degeneration better than no treatment at all, however the greatest preservation of disc health was seen with combined AF and NP repairs. Disclosures: S. Kirnaz: None. C. Wipplinger: None. S. Sloan: None. F. Schmidt: None. A. Schiavinato: E; Fidia Farmaceutici. L. Bonassar: B; Fidia Farmaceutici, 3DBio. R. Hartl: B; Ulrich, BrainLab, DePuy Synthes. F; Zimmer Biomet.Abstracts AnnualForum’19 54ANNUAL FORUM ’19 | LAS VEGAS, NEVADA | OCT. 31–NOV. 2, 2019 CONCURRENT SESSION 8B: LATERAL, BIOLOGICS & HEALTHCARE ECONOMICS FREE PAPERS Paper #70: Lost to Follow-Up in Minimally Invasive Lumbar Spine Surgery Darren Chen, BA 1 ; Avani Vaishnav, MBBS 2 ; Catherine Himo Gang 2 ; Steven McAnany, MD 2 ; Sravisht Iyer, MD 2 ; Todd Albert, MD 2 ; and Sheeraz Qureshi, MD, MBA 2 Weill Cornell Medical College, New York, NY 1 and Hospital for Special Surgery, New York, NY 2 Introduction: Patients who are lost to follow-up (LTF) are a common source of selection bias for clinical outcomes research; systematic differences in outcomes between patients who are followed after spine surgeries versus those who are not followed could lead to skewed conclusions. Aims/Objectives: The purpose of this study is to determine whether minimally invasive (MI) lumbar spine surgery outcomes are different between those who are LTF and those who are not. Methods: We conducted retrospective chart reviews and telephone interviews of 289 patients undergoing MI lumbar surgery from April 1, 2017 to July 1, 2018. Patients were considered LTF if they had missed 2 or more consecutive follow-up visits or both the 6- and 12-month follow-up visits. For lost patients, we compared differences in patient response outcome measures (ODI, VAS back/leg, SF-12 Physical/Mental, PROMIS) between preoperative and interview timepoints; for patients who were not lost, we compared these scores between preoperative and 1-year follow-up timepoints. Results: Of the 289 patients treated, 99 (34.26%) were considered LTF and 190 (65.47%) were not. After applying exclusion criteria, we were successfully able to contact 53/86 (61.6%) of the remaining LTF patients. Independent t-test analysis showed that lumbar patients who were LTF had greater mean increases in PROMIS scores between preoperative and interview/follow-up times than those who were not lost (15.08 vs 10.38, p=0.026). From preoperative to interview/follow- up time points, LTF lumbar fusion patients had greater mean decreases in ODI (-30.94 vs -16.23, p<0.01) and VAS back scores (-4.92 vs -2.99, p=0.044), while also having greater mean increases in PROMIS scores (16.09 vs 10.38, p=0.049). Mann Whitney analysis showed LTF patients also have a shorter median return to driving than not LTF fusion patients (11 days vs 24 days, p=0.02). There were no significant differences in complication rates between lost and not lost patients. The most commonly reported reasons that patients did not return for follow up appointments were that they either forgot (35.8%) or were satisfied with the procedure (24.5%). Conclusions: Patients undergoing MI lumbar surgery—in particular lumbar fusions—who are LTF have improved self- reported outcomes (ODI, VAS back, PROMIS). This is counter to the common notion that patients who are LTF fare worse. We successfully contacted 53 of 86 (61.6%) LTF patients, which suggests that increased efforts to follow-up with these patients could yield substantial response rates. Disclosures: D. Chen: None. A. Vaishnav: None. C. Gang: None. S. McAnany: B; Titan, NuVasive, Stryker K2M. S. Iyer: A; NASS. B; Healthgrades. T. Albert: B; NuVasive, Facet Link. D; Vital 5, Biometrix, InVivo Therapeutics, Spinicity, CytoDyn, ASIP, Crosstrees Medical, Paradigm Spine, PMIG, Invuity, Gentis, Morphogenisis, Surg.IO, Nutriceutical Holdings PRN Physician Recommended Nutriceuticals, Innovative Surgical Designs, Strathspey Crown Holdings II, Pulse Equity Partners, Augmedics, Bonovo Orthopedics, United Health Group. F; Zimmer Biomet, DePuy Synthes. S. Qureshi: B; Stryker K2M, Globus Medical, Paradigm Spine, Spinal Simplicity, LifeLink. D; Avaz Surgical, Vital 5. F; Stryker K2M, RTI. Best Paper Award Finalist Paper #71: The Economic Impact of Non-Reimbursable Events in Open, Minimally Invasive, and Robot- Assisted Lumbar Fusion Surgery Avery Brown, MS 1 ; Katherine Pierce, BS 1 ; Cole Bortz, BS 1 ; Haddy Alas, BS 1 ; Hamid Hassanzadeh, MD 2 ; Lawal Labaran 2 ; Dennis Vasquez-Montes, BS 1 ; Waleed Ahmad, MS 1 ; Sara Naessig, BS 1 ; Shaleen Vira, MD 1 ; Bassel Diebo, MD 3 ; Daniel Sciubba 4 ; Pierce Nunley 5 ; Shaleen Vira 1 ; Paul Park 6 ; Michael Gerling, MD 1 ; Aaron Buckland, MD 1 ; Peter Passias, MD 1 NYU Langone Medical Center, New York, NY 1 ; University of Virginia Medical Center, Charlottesville, VA 2 ; SUNY Downstate, New York, NY 3 ; Hopkins University School of Medicine, Baltimore, MN4; Spine Institute of Louisiana, Shreveport, LA 5 ; and University of Michigan, Ann Arbor, MI 6 Introduction: Lumbar fusion surgery is a constantly evolving field, with recent advances including minimally invasive (MIS) and robot-assisted spine surgery. It is unknown if there has been a commensurate rise in the rates of postoperative non- reimbursable events. Aims/Objectives: Investigate the rates of economic impact of non-reimbursable events in lumbar spine fusion surgery. Methods: Inclusion criteria included surgical patients >18 years of age undergoing lumbar fusion. Patients were categorized into 3 groups based on procedure: open, MIS, and robot- assisted (robot). Open surgery included those undergoing open Abstracts AnnualForum’19 55ANNUAL FORUM ’19 | LAS VEGAS, NEVADA | OCT. 31–NOV. 2, 2019 CONCURRENT SESSION 8B: LATERAL, BIOLOGICS & HEALTHCARE ECONOMICS FREE PAPERS posterior fusion. MIS included those undergoing transforaminal or lateral lumbar interbody fusion with percutaneous screws. Robot-assisted surgery were those undergoing robot-assisted interbody fusion. Propensity score matching was performed for number levels fused. The rates of postoperative complications and non-reimbursable events were assessed for each group. Non-reimbursable events were defined as surgical site infections (SSIs), urinary tract infections (UTIs), and pulmonary embolisms or deep venous thromboembolisms(PE/DVT). The costs of non-reimbursable events were calculated using the PearlDiver database. For robot cases, costs were reflective of operational fees and initial purchase costs. Complications and comorbidities (CC) and major complications and comorbidities (MCC) were assessed according to CMS.gov manual definitions. Results: A total of 360 propensity matched patients (120 open, 120 MIS, 120 robot) were included. Descriptive statistics for the cohort were: age 58.8 ± 13.5, 50% women, BMI 29.4 ± 6.3 kgm2, operation time (OT) 294.4 ± 119.0 minutes, LOS 4.56 ± 3.31 days, EBL 515.9 ± 670.0 mL, and 2.3 ± 2.2 average levels fused. Overall, rates of postop complications were significantly higher in robotic cases versus open and MIS (43% robot vs. 21% open and 22% MIS; p<0.05). When compared to open and MIS, robotic cases had higher rates of non-reimbursable events (12.0% robo vs. 8.0% open and 7.0% MIS, both p<0.001), as well as baseline surgery costs ($60,047.01 robot vs. $42,538.98 open and $41,471.21 MIS). On average, non-reimbursable events costs $20,299.07. The overall costs of care for patients who experienced non-reimbursable events was significantly higher for robotic patients compared to open and MIS ($79,094.35 robot vs. $63,902.18 open and $61,957.87 MIS, both p<0.05). Conclusions: Non-reimbursable events represent a significant burden to cost efficiency in healthcare. While lumbar surgery techniques have advanced, little is known of the effect on non- reimbursable events. When matched for levels fused, robot- assisted surgery patients had 30% higher costs of surgery and significantly higher rates of never events compared to minimally invasive and open spine surgery patients. However, further longitudinal research is needed to fully assess the impact of non-reimbursable events lumbar spine surgery. Disclosures: A. Brown: None. K. Pierce: None. C. Bortz: None. H. Alas: None. H. Hassanzadeh: None. L. Labaran: None. D. Vasquez-Montes: None. W. Ahmad: None. S. Naessig: None. S. Vira: None. B. Diebo: None. D. Sciubba: B; Baxter, Depuy Synthes, Johnson & Johnson, Stryker K2M, Medtronic, NuVasive. P. Nunley: A; Strker K2M, Mesoblast, Organogenesis, Orthofix, Pfizer, Simplify, Spinal Kinetics, Spineology, Vertiflex, Zimmer Biomet. B; ABSS, Centinel Spine, Integrity Spine. C; Camber Spine, Stryker K2M, Spineology. D; Amedica, Camber Spine, Paradigm, Spineology. F; Camber Spine, Integrity Spine. S. Vira: None. P. Park: A; Vertex, Pfizer. B; Allosource, Globus Medical, Medtronic, NuVasive, AANS Spine Section, Journal Of Neurosurgery, Neurosurgery, Operative Neurosurgery, Scoliosis Research Society, The Spine Journal. F; Globus Medical. M. Gerling: None. A. Buckland: None. P. Passias: A; CSRS. B; Medicrea, Spine Wave, Allosource. C; Zimmer Biomet. Paper #72: Return to Activities and Discontinuation of Narcotics After Minimally Invasive Lumbar Spine Surgery Jung Kee Mok, BS 1 ; Avani Vaishnav, MBBS 2 ; Catherine Himo Gang, MPH 2 ; Steven McAnany, MD 2 ; Sravisht Iyer, MD 2 ; Todd Albert, MD2; and Sheeraz Qureshi, MD, MBA 2 . Presented by Darren Chen, BA. Weill Cornell Medical College, New York, NY 1 and Hospital for Special Surgery, New York, NY 2 Introduction: Patients undergoing spinal surgery for degenerative conditions are often concerned about their postoperative recovery. While several previous studies have shown faster short-term recovery with minimally invasive techniques compared to open ones, none have compared return to specific functions in patients undergoing different types of minimally invasive procedures. Aims/Objectives: The purpose of this study was to determine how long it takes patients undergoing either 1-level minimally invasive lumbar decompression or 1-level minimally invasive lumbar fusion to return to work, return to driving, and discontinue narcotic medications. A secondary goal was to determine the difference between the 2 surgical groups. Methods: The analysis included patients who had undergone elective 1-level minimally invasive lumbar decompression or fusion between April 2017 and August 2018. To be included, patients had to have been driving or working preoperatively, or had to have been administered narcotics postoperatively. The number of days it took for patients to return to the activity or to discontinue narcotics was calculated and compared between 1-level minimally invasive lumbar decompression and fusion. Results: All return to activity values are reported in medians. In the return to driving analysis, 1-level minimally invasive lumbar decompression patients (n = 36) took 14 days to return to driving while 1-level minimally invasive lumbar fusion patients (n = 41) took 16 days. In the return to work analysis, 1-level minimally invasive lumbar decompression patients (n = 38) took 16.5 days to return and 1-level minimally invasive lumbar fusion patients (n = 31) took 14 days to return. In terms of discontinuation of narcotics, 1-level minimally invasive lumbar decompression patients (n = 41) took 7 days to discontinue Abstracts AnnualForum’19 56ANNUAL FORUM ’19 | LAS VEGAS, NEVADA | OCT. 31–NOV. 2, 2019 CONCURRENT SESSION 8B: LATERAL, BIOLOGICS & HEALTHCARE ECONOMICS FREE PAPERS narcotics and 1-level minimally invasive lumbar fusion patients (n = 44) took 11.5 days to discontinue narcotics. For all 3 measures, there were no statistically significant differences in the demographic variables between patients who underwent 1-level minimally invasive lumbar decompression and fusion. Conclusions: Our study is the first to show that patients undergoing single level minimally invasive lumbar decompression or fusion procedures can expect to return to work and driving between 2 and 3 weeks after surgery and discontinue narcotic medications between 1 and 2 weeks after surgery. Importantly, our study also shows that there is no statistically significant difference in these postoperative achievements between patients undergoing minimally invasive decompression versus minimally invasive fusion procedures. Disclosures: J. Mok: None. A. Vaishnav: None. C. Gang: None. S. McAnany: B; Titan, NuVasive, Stryker K2M. S. Iyer: A; NASS. B; Healthgrades. T. Albert: B; NuVasive, Facet Link. D; Vital 5, Biometrix, InVivo Therapeutics, Spinicity, CytoDyn, ASIP, Crosstrees Medical, Paradigm Spine, PMIG, Invuity, Gentis, Morphogenisis, Surg.IO, Nutriceutical Holdings PRN Physician Recommended Nutriceuticals, Innovative Surgical Designs, Strathspey Crown Holdings II, Pulse Equity Partners, Augmedics, Bonovo Orthopedics, United Health Group. F; Zimmer Biomet, DePuy Synthes. S. Qureshi: B; Stryker K2M, Globus Medical, Paradigm Spine, Spinal Simplicity, LifeLink. D; Avaz Surgical, Vital 5. F; Stryker K2M, RTI. Paper #73: Minimally Invasive Surgery in Developing World: An Indigenous Approach to Avoid Economic Burden Viswanadha Arun-Kumar, MS 1 ; Viswanadha Bhavya, MS, IDCCM 2 ; and J. Naresh Babu, MS, FNB 1 Mallika Spine Centre, Guntur, India1 and Ramesh Hospitals, Guntur, India2 Introduction: With the increasing use of spinal fusion surgery, many innovations have emerged with the goal to minimize invasiveness and improve outcome. Various advanced minimally invasive (MIS) techniques have been developed with the evolution of specialized retractors, instruments, and implants. However, the question of affordability and availability arises in third world countries where the density of rural population is exceedingly higher. Methods: A total of 25 surgeries (13 lumbar spondylolisthesis and 12 pediatric/adolescent spinal deformity) have been performed, maintaining the principles of MIS with the usage of regular instrumentation. All the cases are performed with regular instruments and implants, which are used in traditional open procedures. Of these, 13 were MIS transforaminal interbody lumbar fusion (MIS TLIF) procedures and 12 were deformity corrective procedures. These cases were compared with counter-part controls (open procedures) and clinico- radiological outcomes were measured at final follow-up. Results: All procedures were successfully performed without conversion into classical approach. There was no significant difference in VAS (both back and leg pain). Although surgery time was not significant in both the categories (p - 1.20), blood loss and length of hospitalization were significantly less in MIS groups (p <0.05). Conclusions: This study documents feasibility of MIS procedures performed with regular instruments and implants. These procedures require no added cost and can be adopted easily, especially in developing countries where the concern is affordability and availability of implants. The added advantages include decreased blood loss, shortened stay in hospital, lower analgesic requirement, and faster recovery of daily life activities. Disclosures: V. Arun-Kumar: None. V. Bhavya: None. J. Babu: None. Best Paper Award Finalist Paper #74: A Prospective, In-Depth Analysis of Perioperative Anterior Thigh Symptoms Associated with a Direct Lateral Access Approach for Lumbar Interbody Fusion Pierce Nunley, MD 1 ; Clint Hill, MD 2 ; John Malloy, DO 3 ; K. Brandon Strenge, MD 2 ; and Marcus Stone, PhD 4 Spine Institute of Louisiana, Shreveport, LA 1 ; The Orthopaedic Institute of Western Kentucky, Paducah, KY 2 ; East Coast Orthopaedics, Pompano Beach, FL 3 ; and Spine Institute of Louisiana Foundation, Shreveport, LA 4 Introduction: Anterior thigh symptoms post-transpsoas lateral approach for lumbar interbody arthrodesis are well documented. However, reports of neurological complications have been largely based on retrospective reviews and are subject to reporting bias. Aims/Objectives: The aim of this analysis was to prospectively characterize adverse perioperative neurological changes associated with a direct lateral transpsoas retroperitoneal tubular retractor system. Further, provider-reported changes were compared versus subject-reported changes. Abstracts AnnualForum’19 57ANNUAL FORUM ’19 | LAS VEGAS, NEVADA | OCT. 31–NOV. 2, 2019 CONCURRENT SESSION 8B: LATERAL, BIOLOGICS & HEALTHCARE ECONOMICS FREE PAPERS Methods: Data were gathered in a prospective, multicenter, IRB-approved post-market study of adult subjects presenting with degenerative disc disease at 1 or 2 adjacent levels from L2 to L5. Subjects self-reported thigh pain, hip flexion weakness, and knee extension weakness on a 100 mm Visual Analog Scale (VAS) at the preoperative visit, prior to hospital discharge, and at 2-week, 6-week, 3-month, 6-month, and 12-month postoperative visits. Clinical assessments including muscle strength, Achilles reflexes, patellar reflexes, and sensory testing were performed at the same timepoints. Multiple questions specific to lateral access not typically collected in lumbar fusion studies were included in the analysis. Results: One hundred fifteen subjects (115)—71 females (61.7%), with a mean age of 64.0 and mean BMI of 30.8 kgm2— were included for analysis. Objective neurological exam showed 17 (14.8%) subjects with access-sided adverse changes from baseline at hospital discharge. These 17 included 5 patients (4.4%) with changes in strength, 5 (4.4%) with sensation changes, and 11 (9.6%) with reflex changes. Of these, 2 subjects had changes in both strength and reflexes; 2 had changes in both sensation and reflexes. All strength and sensation changes were resolved by 6 weeks. All reflex changes resolved by 3 months. Twenty-two subjects (19.1%) reported increased thigh pain (>20 mm) at discharge. All were resolved by 3 months. Forty-four subjects (38.3%) reported increased hip flexion or extension weakness (>20 mm), with 29 (65.9%) resolved by 6 weeks, 37 (84.1%) resolved by 3 months, 41/45 (93.2%) resolved by 6 months, and 3 have additional follow-up pending. Of the 17 subjects with objectively identified changes, 7 also reported subjective changes. Only 2 subjects (11.8%) reported symptoms (weakness) correlated with objectively reported results (strength). Conclusions: This unique prospective study is the first to our knowledge that captures in-depth subjective and objective data specific to lateral access surgery. The perioperative results provide a rare illustration of adverse changes and their almost complete resolution within 3 months. Further research to understand the differences in clinician reported versus subject reported changes is warranted. Disclosures: P. Nunley: A; Spineology. B; Stryker K2M, Zimmer Biomet, Spineology, Vertiflex, Camber Spine, Integrity Spine, Centinel Spine. C; Stryker K2M, Zimmer Biomet, Camber Spine, Integrity Spine. D; Amedica, Paradigm Spine, Spineology, Camber Spine. F; Zimmer Biomet, Stryker K2M, Camber Spine, Integrity Spine. C. Hill: A; Spineology. B; Globus Medical, Spineology. J. Malloy: B; Spineology. K. Strenge: A; Spineology. B; Spineology. M. Stone: A; Spineology. Paper #75: Comparative Analysis of Vascular Anatomy in OLIF51 Surgery By Using MRI and Intraoperative Enhanced CT Hiroyuki Tachi, MD 1 ; Yoshihisa Kotani, MD,PhD 2 ; Yumejiro Nakamura, MD 1 ; and Norimasa Iwasaki, MD,PhD 3 Steel Memorial Muroran Hospital, Muroran, Japan 1 ; Kansai Medical University Medical Center, Osaka, Japan 2 ; and Hokkaido University Hospital, Sapporo, Japan 3 Introduction: Several advantages of lumbosacral anterior lumbar interbody fusion (ALIF) have been reported in terms of superior stability, broad bone graft area, and indirect neural decompression. We have performed OLIF51 (lateral position mini-ALIF) in over 80 cases and have found out the intraoperative movement of intra-abdominal structures, especially vascular tissues. Aims/Objectives: This study aimed to analyze vascular anatomy in OLIF51 surgery by using MRI and intraoperative enhanced CT. Methods: A total of 18 patients receiving OLIF51 was evaluated. The average age was 68.4 years (range, 62-84). The applied disorders were L5 isthmic and degenerative spondylolisthesis, foraminal stenosis, pseudarthrosis and adjacent segment degeneration, and etc. We utilized 1.5T/3T lumbar MRI scan in supine position preoperatively and vein enhanced O-arm 3D scan in right decubitus position intraoperatively. We measured the distance from midline to right and left common iliac vein in L5 inferior endplate and S1 superior endplate level (RCIV L5,S1/ LCIV L5,S1) and the distance between right and left common iliac vessels (CIV) in axial view (central corridor window [CCW] L5,S1) and change of CIV and CCW from preoperative MRI to intraoperative CT (RCIVCT-MRI L5,S1/ LCIVCT-MRI L5,S1/ CCWCT-MRI L5,S1). The distance from CIV bifurcation to L5 inferior endplate in sagittal view (CIVsag) and change of sagittal CIV position from MRI to intraoperative CT (CIVsagCT-MRI) were also measured. Results: The average RCIV/LCIV L5 moved to 0.8 mm right/ 3.8 mm right from MRI to CT, and RCIV/LCIV S1 moved to 0.3 mm left / 6.9 mm right. The average CCW L5/S1 was 3.6 mm/2.5 mm shortened from MRI to CT, respectively. The average CIVsag moved to 6.3 mm caudally from MRI to CT. There are no significant related factors identified such as BMI, past abdominal surgery, etc. Conclusions: Although OLIF51 has been reported as an excellent MIS procedure, the intraoperative vascular movement occasionally causes the difficulty in surgical approach to 51 disc. In this study, CIV moved caudally and to right from supine position to right decubitus position due to gravity. Although Abstracts AnnualForum’19 58ANNUAL FORUM ’19 | LAS VEGAS, NEVADA | OCT. 31–NOV. 2, 2019 CONCURRENT SESSION 8B: LATERAL, BIOLOGICS & HEALTHCARE ECONOMICS FREE PAPERS the movement of abdominal organs in right decubitus position effectively improves the access to 51, we also need to be aware of the significant vascular movement in OLIF51 surgery. This study serves as important quantitative data of vascular tissues in OLIF51 surgery. Disclosures: H. Tachi: None. Y. Kotani: None. Y. Nakamura: None. N. Iwasaki: None. Paper #76: Psoas Muscle Mass are Maintained and No Progress of Fatty Degeneration After LLIF Tetsuro Hida, MD 1 ; Gregory Mundis Jr., MD 2 ; and Robert Eastlack, MD 2 Nagoya University, Nagoya, Japan 1 and Scripps Clinic, San Diego, CA 2 Introduction: The effect of surgical dissection through the psoas muscle on muscle volume and fatty degeneration from lateral lumbar interbody fusion (LLIF) is not well understood. This study aims to determine the effect of dilation through the psoas muscle during LLIF as assessed by MRI following 1- year of postoperative recovery. Aims/Objectives: To study whether psoas muscle injury normalizes following LLIF surgery. Methods: Consecutive patients undergoing L4-5 single level LLIF were enrolled and followed for a minimum of 1 year. Using pre- and 1-year postoperative axial T2 MRI at L4-5, the cross- sectional area (CSA) of the psoas muscle was measured both ipsi- and contralateral to the approach. Intramuscular T2 high intensity area was measured with the threshold method and defined as fat area (FA). Outcomes were assessed with ODI and analysing. We used paired T-test and Pearson’s correlation for statistical analysis. P<0.05 was considered significant. Results: A total of 20 patients (7 males, 13 females, mean 68 years) were analyzed. There was no significant difference in CSA before and after surgery on both sides (preop/postop; 1126 ± 345 mm2 / 1163 ± 343 mm2 at approach side, p = 0.39; 1110 ± 279 mm2 / 1149 ± 274 mm2 at opposite side, p = 0.30). There was no difference in FA before and after surgery on both sides (preop/postop; 43 ± 83 mm2/ 165 ± 80 mm2at ipsi-, p = 0.36; 186 ± 140 mm2/ 172 ±92 mm2 and contralateral side, p = 0.61). There was no difference in preop to postop CSA or FA between ipsi- and contralateral side. There were no significant correlations between clinical symptom (ODI and NRS) and muscle parameters (CSA and FA). Conclusions: Psoas muscle mass was maintained at 1-year postop despite dilation through the psoas muscle, with no evidence of fatty degeneration both ipsi- and contralateral to the approach side. There was no association between psoas image findings and postoperative symptoms. In LLIF, the influence of surgical invasion of the psoas muscle based on postop MRI characterization and clinical symptoms was insignificant. Disclosures: T. Hida: None. G. Mundis Jr.: A; NuVasive. B; NuVasive. C; Depuy Synthes, Stryker K2M, NuVasive. F; Stryker K2M, NuVasive. R. Eastlack: A; NuVasive. B; Aesculap, Baxter, Stryker K2M, NuVasive, Spineology, SI Bone, Titan. C; Radius. D; Alphatec, Carevature, Invuity, Nocimed, NuVasive, SeaSpine, Spine Innovations. F; Globus Medical, NuVasive, SeaSpine, SI Bone.Abstracts AnnualForum’19 59ANNUAL FORUM ’19 | LAS VEGAS, NEVADA | OCT. 31–NOV. 2, 2019 CONCURRENT SESSION 8C: YOUNG SURGEON FREE PAPERS Paper #77: The Effect of Surgical Decompression and Fusion on Balance in Patients with Degenerative Lumbar Spondylolisthesis Ram Haddas, PhD; Peter Derman, MD; John Burleson, MD; Andrew Block, PhD; and Isador Lieberman, MD Texas Back Institute, Plano, TX Introduction: Degenerative lumbar spondylolisthesis (DLS) is a condition in which a vertebra subluxates relative to an adjacent vertebra in the absence of a disruption in the neural arch. While the existing literature demonstrates that decompression and fusion can successfully alleviate pain and reduce disability in patients with DLS, no studies to date have used quantitative dynamic testing to determine the effect of surgery on CoE measures in this patient population. Aims/Objectives: To quantify the effect of lumbar decompression and fusion surgery on balance and stability in patients with DLS and compare them to controls. Methods: Prospective cohort study. Forty-two DLS patients performed a series of functional balance tests a week before and 3 months after surgery and were compared to 26 controls. The outcome measures included range of sway (RoS) and total sway for the center of mass (CoM) and head in the sagittal, coronal and axial planes, along with leg and back visual analog scale (VAS), Oswestry Disability Index (ODI), Fear/Avoidance Behavior Questionnaire (FABQ), Tampa Scale of Kinesophobia (TSK), and Demoralization scale. Results: RoS for the CoM (p<0.005) and head (p<0.017) decreased in all planes postoperatively. Reductions in CoM (p=0.001) and head total sway (p=0.001) were also observed after surgery. Furthermore, patients with DLS reported strong improvements in VAS low back (p=0.001), VAS leg (p=0.001), ODI (p=0.001), FABQ Physical (p=0.003), TSK (p=0.001), and demoralization (p=0.044) with surgical intervention. Although total sway was reduced after surgery, it did not return to the level of normal controls as demonstrated with more total sway of their CoM (p=0.002) and head (p=0.001), as well as more sagittal head RoS (p=0.048). Conclusions: This study confirms that surgical intervention for degenerative spondylolisthesis is effective at reducing disability, back and leg pain, demoralization, kinesiophobia, and fear- avoidance beliefs related to physical activity in patients with DLS. Furthermore, such patients exhibit a significantly more stable stance after surgery. However, balance parameters did not completely normalize by 3-months postoperatively. Disclosures: R. Haddas: A; Medtronic, SI-Bone, Aspen Medical Products, Cervical Spine Research Society. P. Derman: None. J. Burleson: None. A. Block: None. I. Lieberman: None. Paper #78: Rate of Fusion in Minimally Invasive Transforaminal Lumbar Interbody Fusion Chad Campion, MD; Catherine Olinger, MD; Kirk Thompson, MD; and Raymond Gardocki, MD Campbell Clinic/University of Tennessee, Germantown, TN Introduction: Minimally invasive transforaminal lumbar interbody fusion (MIS TLIF) has been shown to be an effective intervention for the treatment of symptomatic lumbar pathology. Aims/Objectives: The primary aim of the present study was to investigate the rate of fusion with elective MIS TLIF performed by a single surgeon at 1 year. We secondarily analyzed radiographic outcomes based on change in disc height, lumbar lordosis, Cobb angle, and listhesis of the treated levels at 1 year. Methods: Electronic medical records of 143 patients (75 females, 68 males) who underwent MIS TLIF performed by a single surgeon from January 1, 2010 to June 1, 2015 were reviewed. Patient fusion rates, height, Cobb angles, lordosis, and listhesis were analyzed from radiographs preoperatively and at 3 months and 1 year. Patient-reported outcomes on a visual analog scale (VAS) and Oswestry Scores (ODI) were recorded at the same time periods. Results: One hundred and twelve patients (88%) demonstrated radiographic fusion versus 15 patients (12%) with suspected nonunion at 1 year. Patients who achieved radiographic fusion had statistically significant less lumbar lordosis at the preoperative, postoperative, and 1-year time points versus those with radiographic nonunion. There were statistically significant improvements in lordosis from preoperative to 3 months and 1 year measured at the L3-4 level. Spinal motion unit height was statistically improved at 3 months for both L4-5 and L5-S1 and improved at 1 year for L5-S1 levels. There was no statistical difference in preoperative versus 3 months and 1 year lordosis, height, or listhesis at the remaining documented levels. Correction in listhesis at the L4-5 was significantly correlated to improvement in VAS (rho -.24;p=0.04). There was no correlation between the remaining radiographic parameters and ODI or VAS change at final follow-up. Next >