< PreviousAbstracts AnnualForum’19 30ANNUAL FORUM ’19 | LAS VEGAS, NEVADA | OCT. 31–NOV. 2, 2019 Conclusions: MEP monitoring has additional value to sEMG and tEMG during LLIF procedure at L4-5 by providing the surgeon of impending injury that would otherwise go unnoticed. Continued prospective data collection is necessary to ascertain the sensitivity and specificity of this neuromonitoring modality. Disclosures: N. Alan: A; SOLAS-Grant Award. G. Adams: None. N. Agarwal: None. A. Ozpinar: None. J. Balzer: None. V. Miele: None. A. Kanter: F; Zimmer Biomet, NuVasive. Paper #35: Percutaneous Transforaminal Lumbar Interbody Fusion with Expandable Cage Through Kambin’s Triangle: Initial Results and Feasibility Timothy Wang, MD; Vikram Mehta, MD MPH; Eric Sankey, MD; Alexia Bwensa; Mostafa Gabr, MD; C. Rory Goodwin, MD PhD; Isaac Karikari, MD; and Muhammad Abd-El-Barr, MD PhD Duke University Medical Center, Durham, NC Introduction: Minimally invasive transforaminal lumbar interbody fusion (MIS TLIF) is a common procedure in lumbar spine fusion. Typically, a medial facetectomy is performed, allowing access to the intervertebral disc and insertion of a cage. Percutaneous access to the disc through Kambin’s triangle obviates the need for a medial facetectomy and is thus hypothesized to decrease patient morbidity and pain. Most authors have described the use of static cages through this approach or the use of a porous allograft-containment mesh. In this paper, we describe the clinical outcomes and feasibility of percutaneous TLIF with an expandable cage through Kambin’s triangle. Aims/Objectives: Describe the importance of percutaneous TLIF, the surgical approach to Kambin’s triangle, and identify percutaneous TLIF with an expandable cage as an effective treatment for lower extremity radiculopathy and spondylolisthesis. Methods: A retrospective review of patients undergoing single-level percutaneous TLIF via Kambin’s triangle with an expandable cage was performed. Demographic information, pre- and postoperative radiographic factors, perioperative data, and complications were recorded. Results: Eight total patients (2 males) were included in this study. Average age was 56.4±12.4 years, and average BMI was 28.8.4±5.6 kg/m2. Average preoperative spondylolisthesis, anterior and posterior disc height, canal area and diameter, and left and right neuroforaminal area was 7.8±4.4 mm, 9.0±3.6 mm, 6.4±1.8 mm, 1.6±0.5 cm2, 8.3±4.9 mm, 0.8±0.5 cm2, 0.7±0.3 cm2, respectively. On average, there was 2.0±2.1 mm, 2.4±4.1 mm, 1.1±2.4 mm correction of spondylolisthesis, anterior, and posterior disc height, respectively. Average length of stay and blood loss was 2.8 days and 35 mL, respectively. All patients experienced significant reduction in back and leg pain; 1 patient experienced 30-day readmission for intractable pain but a CT scan did not demonstrate screw breach or anatomic cause for symptoms. This patient was managed by the pain service and discharged without further neurosurgical intervention. Conclusions: Initial experiences have shown than percutaneous TLIF with an expandable cage through Kambin’s triangle is a safe and clinically efficacious procedure for reducing lumbar spondylolisthesis and radiculopathy. Disclosures: T. Wang: None. V. Mehta: None. E. Sankey: None. A. Bwensa: None. M. Fabr: None. C. Goodwin: None. I. Karikari: None. M. Abd-El-Barr: None. Paper #36: A Radiographic Analysis of Segmental Sagittal Correction Following Interbody Fusion Through an Antepsoas Approach Joseph Lombardi, MD; Nathan Lee, MD; Jun Kim, MD; and Ronald Lehman, MD Columbia University, New York, NY Introduction: The antepsoas approach for lumbar interbody fusion (APLIF) has been described to offer many unique advantages including a psoas sparing corridor, avoidance of the lumbar plexus, absence of neuromonitoring requirements and ability to place posterior instrumentation without patient repositioning. To date, no study has examined the segmental sagittal correction that can be achieved through APLIF. Aims/Objectives: The objective of this study was to determine if significant sagittal correction can be achieved through use of hyperlordotic interbody cages when placed through an antepsoas approach. Methods: Twenty-four consecutive patients undergoing APLIF for treatment of degenerative conditions of the spine by a single surgeon were reviewed. Segmental sagittal cobb angles (SCA) were measured at 3 time points: Preoperative, intraoperative after placement of interbody, and intraoperative after posterior instrumentation. Additional data points included: surgical levels, interbody characteristics, and patient demographics. CONCURRENT SESSION 2C: YOUNG SURGEONS’ FREE PAPERSAbstracts AnnualForum’19 31ANNUAL FORUM ’19 | LAS VEGAS, NEVADA | OCT. 31–NOV. 2, 2019 Results: A total of 31 levels in 24 patients were analyzed for changes in SCA following placement of interbody cages and posterior instrumentation. On average, interbodies placed through APLIF had an increase in SCA by 10.85 degrees per level with 9.66 degree arising from interbody cages alone prior to instrumentation. The 24 degree hyperlordotic cages trended towards a greater SCA correction (14.7 degrees) when compared to 18 degree cages (11.7 deg). There was a statistically significant difference in SCA correction when comparing 18-deg cages (11.7) to 12-deg cages (6.8)(p=0.01) and 24-deg cages (11.7) to 12-deg cages (6.8) (p=0.01). Conclusions: APLIF provides excellent segmental sagittal correction averaging 10.85 degrees per level with 9.66 deg arising from the interbody cage alone. There is a trend for increasing SCA correction with larger hyperlordotic cages. This is likely due to an ability to perform anterior soft tissue releases as well as placement of large hyperlordotic cages through an antepsoas approach. Disclosures: J. Lombardi: None. N. Lee: None. J. Kim: None. R. Lehman: None. Paper #37: Predictive Machine Learning Algorithm to Calculate Probability of Developing Subsidence After Lateral Lumbar Interbody Fusion Ahmed Jorge, PhD; Nitin Agarwal, MD; Edward Andrews, MD; Alp Ozpinar, MD; Nima Alan, MD; David Hamilton, MD; David Okonkwo, MD, PhD; and Adam Kanter, MD University of Pittsburgh Medical Center, Pittsburgh, PA Introduction: Graft subsidence has been associated with worse outcomes after lateral lumbar interbody fusion (LLIF), including recurrence of foraminal stenosis, sagittal imbalance, and back pain. However, the role of demographic data, spinopelvic parameters, and level of operative pathology in the development of subsidence is not well characterized. Aims/Objectives: In this study, we aimed to determine the effects of these parameters on the occurrence of subsidence after LLIF. Methods: A retrospective review of a prospectively maintained database from 2008 to 2015 was conducted to identify patients undergoing stand-alone LLIF. Sacral slope (SS) was measured using long cassette films postoperatively (standing, 36-inch long). A support-vector machine (SVM), a common machine- learning algorithm, was utilized to calculate the probability of subsidence as a function of age, sacral angle, and operative spinal level (custom-code; MATLAB-MathWorks,Inc, Natick, MA). A receiver operating curve based on this model was then calculated and yielded the sensitivity and specificity to detect an increase in the probability of subsidence. Results: Two hundred seventy-two patients underwent stand- alone LLIF, 18 (7%) of which developed cage subsidence for which revision surgery was necessary. The probability of developing subsidence increased to approximately 15% in patients with a SS of approximately 35-50 degrees and those between 65 to 80 years of age. L3-L4 and L4-L5 involvement in subsidence had the most pronounced effects, both at similar SS and age range. The overall model sensitivity and specificity to detect an increase in the probability of developing subsidence was 71% and 73% respectively. Conclusions: Our model identified specific age ranges, sacral slope, and spinal levels involved with an increase in the probability of subsidence with a high degree of sensitivity and specificity. This model could be potentially used to stratify patients to minimize their risk for subsidence, for example, by considering posterior supplementation perioperatively. Disclosures: A. Jorge: None. N. Agarwal: None. E. Andrews: None. A. Ozpinar: None. N. Alan: None. D. Hamilton: None. D. Okonkwo: F; Zimmer Biomet, NuVasive. A. Kanter: F; Zimmer Biomet, NuVasive. Paper #38: When Indirect Decompression Fails: A Prospectively Collected Series of Patients Requiring Secondary Direct Decompression After Lateral Interbody Fusion Clinton Morgan, MD; Jacob Godzik, MD; Corey Walker, MD; Harrison Farber, MD; Courtney Hemphill, BA; and Juan Uribe, MD Barrow Neurological Institute, Phoenix, AZ Introduction: Eloquent execution of lumbar lateral interbody fusion (LLIF) affords the patient minimally-invasive decompression and a large surface area for arthrodesis at motion segments. However, complication avoidance is critical and there is significant morbidity attached to re-operation at the index LLIF level when symptoms fail to improve or worsen following this procedure. Furthermore, some patients are known to go on to require secondary direct decompression after LLIF-driven indirect foraminal decompression fails. It is important to understand which patients fail at the index LLIF level, why they fail, and common trends. CONCURRENT SESSION 2C: YOUNG SURGEONS’ FREE PAPERSAbstracts AnnualForum’19 32ANNUAL FORUM ’19 | LAS VEGAS, NEVADA | OCT. 31–NOV. 2, 2019 Aims/Objectives: The aims of this study were to evaluate a prospectively collected series of LLIF patients for common features of those patients who required secondary re- operation, which included the index LLIF level. Methods: After IRB approval was obtained, clinical, radiographic, and operative data were collected for 127 consecutive LLIF patients at a single institution by a single expert surgeon. Secondary direct decompression was defined as an unexpected return to the operating room for laminectomy or foraminotomy. Results: We identified 11 patients (8.7%) who required revision surgery at the index LLIF between July 2017 and May 2019. Most requiring revision were male (82%) and the median age was 65. The most common reason for re-operation was persistent radiculopathy at the level of the index LLIF. Interestingly, the contralateral nerve root to the side of approach appeared critical. We found that all (5/5) of cases requiring delayed secondary direct decompression involved a right-sided radiculopathy when a left-sided LLIF approach was chosen. The second most common reason for re-operation involved pseudoarthrosis-mediated posterior hardware failure (5/11). This sub-group included rod failure, screw pullout, and need for posterior fixation due to ongoing dynamic instability at the LLIF level. Finally, 1 patient developed an adjacent segment herniated thoracic disc causing sub-acute paraparesis. Conclusions: LLIF surgery, when performed by an expert surgeon, has exceedingly low rates of re-operation. Careful attention must be paid to the successful indirect decompression of the contralateral foramen when performing this procedure as every case of secondary direct re-operation and decompression was performed on the contralateral nerve root. Symptomatic pseudoarthrosis rates appear low, and mostly manifest in posterior hardware pull-out. Disclosures: C. Morgan: None. J. Godzik: None. C. Walker: None. H. Farber: None. C. Hemphill: None. J. Uribe: B; NuVasive, SI-Bone. Paper #39: Novel MIS 3D NAV Single Step Pedicle Screw System: Workflow, Accuracy, and Initial Clinical Experience Franziska Schmidt, MD; Hervé Lekuya; Sertac Kirnaz; Nick Hernandez; Ibrahim Hussain; Louis Chang; Christoph Wipplinger; Cameron Rawanduzy; and Roger Härtl Weill Cornell, New York, NY Introduction: Single step pedicle screw system (SSPSS)was developed for minimally invasive spine surgery (MISS). Aims/Objectives: We performed this study to report on safety, workflow, and our initial clinical experience with this novel technique. Methods: The prospective case study was conducted on data collected from patients who underwent MIS pedicle screw fixation between October 2017 and April 2018 using a novel single step 3D navigated pedicle screw system (Viper Prime System (DePuy Synthes, Raynham, MA). Outcome measurements were obtained from intraoperative CT navigation, including sagittal, axial, and coronal reformatted images. The images were evaluated to determine pedicle wall penetration after surgery. Breaches were classified as grade 1 (< 2 mm), grade 2 (2-4 mm), or grade 3 (< 4 mm), and as cranial, caudal, medial, and lateral. Results: Our study included 135 screws in 24 patients. SSPSS eliminated K-wires and multiple steps traditionally necessary for MIS pedicle screw insertion and therefore facilitated workflow. The median time per screw was 2.45 minutes. Three screws were corrected intraoperatively. Pedicle wall penetration occurred in 14 screws (10%). Grade 1 breaches occurred in 4 screws (3%) and grade 2 breaches occurred in 10 screws (7%). Lateral breaches were observed more often than medial breaches. The accuracy rate in our study was 90% (Grade 0 breach). No revision surgeries were needed and no complications occurred. Conclusions: We conclude that SSPSS with navigation is a safe, accurate, and efficient tool for MISS. Our accuracy rate is comparable to that found in the literature. We experienced an improvement in workflow and efficiency with SSPSS. Disclosures: F. Schmidt: None. H. Lekuya: None. S. Kirnaz: None. N. Hernandez: None. I. Hussain: None. L. Chang: None. C. Wipplinger: None. C. Rawanduzy: None. R. Härtl: None. CONCURRENT SESSION 2C: YOUNG SURGEONS’ FREE PAPERSAbstracts AnnualForum’19 33ANNUAL FORUM ’19 | LAS VEGAS, NEVADA | OCT. 31–NOV. 2, 2019 Paper #40: Accuracy of Percutaneous Pedicle Screw Placement in Minimally Invasive Spine Surgery: Fluoroscopic Guidance Versus 3D-Navigation Guang-ting Cong, MD 1 ; Avani Vaishnav, MBBS 2 ; Joseph Barbera, MD 1 ; Hiroshi Kumagai, MD 2 ; James Dowdell, MD 2 ; Catherine Himo Gang 2 ; Sravisht Iyer, MD 2 ; Steven McAnany, MD 2 ; Todd Albert, MD 2 ; and Sheeraz Qureshi 2 Icahn School of Medicine at Mount Sinai, New York, NY 1 and Hospital for Special Surgery, New York, NY 2 Introduction: Posterior spinal instrumentation for fusion using intraoperative CT navigation is gaining traction as an alternative to the conventional 2D fluoroscopic-guided approach to percutaneous pedicle screw placement. However, few studies to date have directly compared outcomes of these 2 minimally invasive instrumentation methods. Aims/Objectives: The purpose of the study was to compare accuracy of percutaneous pedicle screw placement using 3D intraoperative navigation guidance versus 2D fluoroscopy. Methods: A consecutive cohort of patients undergoing primary percutaneous posterior lumbar spine instrumentation for spine fusion was retrospectively reviewed. Revision surgeries or cases converted to open were excluded. Accuracy of screw placement was assessed using a postoperative CT scan with blinding to the surgical methods used. The Gertzbein-Robbins classification was used to grade cortical breach: Grade 0 (< 0 mm cortical breach), Grade I (< 2 mm), Grade II (2-4 mm), Grade III (4-6 mm), and Grade IV (> 6 mm). Screws were further scrutinized for presence of inferior/medial pedicle breach, tip breach, endplate breach, and facet violation. Based on this data, screw accuracy was graded using an ordinal grading scheme devised a priori based on opinion amongst the authors: good (no breach), acceptable (pedicle breach within the “safe zone” of up to 4 mm superior/lateral or 2 mm inferior/medial, or any distance of tip breach), or poor (facet violation into unfused level, breach outside of safe zone). Statistical comparisons were made between screws placed by CT navigation and those placed by fluoroscopic guidance. Results: CT navigation was found to significantly improve accuracy of screw placement (p<0.022;. There was significantly more facet violation of the unfused level in the fluoroscopy group versus the CT group (9% vs 0.5%; p<0.0001). There was also a higher proportion of poor screw placement in the fluoroscopy group (10.1% vs 3.6%). No statistical difference was found in the rate of tip breach, inferomedial breach, or lateral breach. Regression analysis showed that fluoroscopy had twice the odds of incurring poor screw placement as compared to CT navigation. Conclusions: This radiographic study comparing screw placement in minimally invasive fluoroscopy- versus CT navigation-guided lumbar spine instrumentation provides evidence that CT navigation significantly improves accuracy of screw placement, especially in optimizing the screw trajectory so as to avoid facet violation. Long term follow-up studies should be performed to ascertain whether this difference can contribute to an improvement in clinical outcomes. Disclosures: G. Cong: None. A. Vaishnav: None. J. Barbera: None. H. Kumagai: None. J. Dowdell: None. C. Gang: None. S. Iyer: A; NASS. B; Healthgrades. S. McAnany: B; Titan, NuVasive, Stryker K2M. T. Albert: B; NuVasive Inc., Facet-Link. D; Gentis, Bonovo Orthopedics, Biometrix, InVivo Therapeutics, Spinicity, Crosstrees Medical, Paradigm Spine, Invuity, ASIP, PMIG, Vital 5, Innovative Surgical Designs, CytoDyn, Morphogenisis, Surg.IO, Nutriceutical Holdings PRN Physician Recommended Nutriceuticals, Strathspey Crown Holdings II, Pulse Equity Partners, Augmedics, 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; RTI, Stryker K2M. Paper #41: Endoscopic Decompression of Epidural Spinal Metastasis Causing Lumbar Radiculopathy Through a Transforaminal Approach: Report of 2 Cases Fraser Henderson Jr., MD; Zachary Hubbard, MD MPH; Samuel Jones, BS; Jessica Barley, PhD; and Bruce Frankel, MD Medical University of South Carolina, Charleston, SC Introduction: Radiculopathy in patients with metastatic spine disease may be palliated with open or microsurgical techniques. However, delay of chemoradiation, infection risk, extended hospitalization periods, and surgical site pain may complicate surgical efforts to improve these patients’ lives. Aims/Objectives: Endoscopic approaches, heretofore used almost exclusively in degenerative spine disease, may also palliate debilitating pain while mitigating the drawbacks of surgical intervention in providing focal tumor debulking. Specimen for histopathologic diagnosis, which is of increasing importance in oncology treatments, may also be obtained by the endoscopic approach. Methods: Two patients were treated with an endoscopic approach for palliation of metastatic disease. A 61-year- old woman with right thigh pain and weakness referable to a foraminal component of metastatic disease underwent transforaminal endoscopic decompression through a single port with resolution of her primary pain complaint. A 50-year- old man with history of urothelial cancer presenting with CONCURRENT SESSION 2C: YOUNG SURGEONS’ FREE PAPERSAbstracts AnnualForum’19 34ANNUAL FORUM ’19 | LAS VEGAS, NEVADA | OCT. 31–NOV. 2, 2019 L5 radicular pain referable to foraminal tumor compression underwent a similar procedure with stabilization of his primary pain complaints. Results: Both patients received biopsy-proven results. The first had complete pain relief and resolution of weakness. The second patient had appreciated stabilization of pain but not complete relief. Neither patient experienced any surgical complication. Both were observed inpatient overnight out of an abundance of caution. Conclusions: Endoscopic technique may allow direct visualization with minimal morbidity for effective decompression of symptomatic metastatic disease resulting from compression of the exiting and traversing nerve roots. Patients compromised from systemic disease may benefit from this less invasive approach that requires neither endotracheal intubation nor extended hospital stay. Disclosures: F. Henderson Jr.: None. Z. Hubbard: None. S. Jones: None. J. Barley: None. B. Frankel: None. Paper #42: Percutaneous Endoscopic Transforaminal Interbody Fusion Through Bi-Portal Technique Javier Quillo-Olvera, MD; Javier Quillo-Reséndiz, MD; Diego Quillo-Olvera, MD; and Jin-Sung Kim, MD, PhD The Brain and Spine Care, Minimally Invasive Spine Surgery Center, Hospital H+ and Hospital Star Medica, Queretaro City, Mexico. Introduction: Transforaminal lumbar interbody fusion (TLIF) in patients with low back pain (LBP) and unilateral radicular symptoms due to instability has demonstrated encouraging outcomes. However, the approach can be iatrogenic with paraspinal muscles, and sometimes preparation of the endplates is not sufficient. Aims/Objectives: We decided to perform a prospective case- control study with a nine month cohort of 10 patients who underwent a new technique of TLIF, the full-endoscopic bi- portal unilateral (UBE) TLIF, and to present our preliminary results. Methods: We included 10 patients who underwent UBE-TLIF from February 2018 to May 2018. Inclusion criteria were chronic LBP treated by conservative strategies without improvement for at least 8 weeks, unstable low-grade spondylolisthesis (I or II) with mild or severe degenerative disc disease with associated foraminal stenosis, and unilateral radicular symptoms. We evaluated all patients preoperatively and postoperatively immediately after surgery and at 1, 3, 6, 9, 12, and 24-months by using the Visual Analog Scale (VAS) for back and leg pain. The Oswestry Disability Index (ODI) was used in the preoperative and in the 9th month follow-up, along with Macnab criteria for satisfaction. The radiological outcome also was evaluated. Statistical analysis for comparing changes over time in all the evaluations was done. Results: All the patients completed the 9-month assessments. Mean age was 53.2 (6 females and 4 males). Four L4-L5 and 6 L5-S1 levels were operated on. The mean surgical time was 168 minutes and mean intraoperative bleeding 70 mL. All the cases were discharged on the next day. No patient required postoperative narcotics for pain control. Both VAS and ODI decreased significantly from preoperative to postoperative (p<0.05), and Macnab criteria resulted in 9 patients referring excellent and 1 good outcome. Radiological evaluations showed a proper location of the cage into the intervertebral space and an appropriate direct decompression. Conclusions: Despite the small size of the sample, we concluded that percutaneous endoscopic bi-portal unilateral TLIF is another minimally invasive alternative for patients with low-grade spondylolisthesis with axial and unilateral radicular symptoms. All patients showed acceptable short-term clinical results in the cohort at 9 months. We await the 12-month outcomes to evaluate the fusion status. However, the direct visualization of the neural elements, excellent preparation of the endplates with direct visualization through the endoscopic portal and minimum postoperative pain are some advantages observed in our study. Disclosures: J. Quillo-Olvera: None. J. Quillo-Reséndiz: None. D. Quillo-Olvera: None. J. Kim: None. Paper #43: What PROMIS Scores Correlate with Severe Disability in Cervical Spine Surgery? Michael Steinhaus, MD; Francis Lovecchio, MD; Lauren Barber, MD; Karim Shafi, MD; Daniel Stein, BS; Thomas Ross, RN; Jingyan Yang, PhD; Todd Albert, MD; Darren Lebl, MD; Russel Huang, MD; Bernard Rawlins, MD; Frank Schwab, MD; Virginie Lafage, PhD; and Han Jo Kim, MD Hospital for Special Surgery, New York, NY Inroduction: The National Institutes of Health (NIH) Patient Reported Outcomes Measurement Information System (PROMIS) has demonstrated favorable psychometric properties in patients with cervical pathology. As PROMIS is a global outcome measure, interpreting the clinical implications of PROMIS scores in patients with cervical spine surgery may be CONCURRENT SESSION 2C: YOUNG SURGEONS’ FREE PAPERSAbstracts AnnualForum’19 35ANNUAL FORUM ’19 | LAS VEGAS, NEVADA | OCT. 31–NOV. 2, 2019 difficult.implications of PROMIS scores in patients with cervical spine surgery may be difficult. Aims/Objectives: To study correlation of PROMIS Physical Function (PF) and Pain Interference (PI) with Short-Form 36 Physical Component Score (PCS) and Neck Disability Index (NDI) and to define values that correlate with severe disability in patients with cervical spinal pathology. Methods: Adult patients indicated for cervical spine surgery at a single institution between 2016-2018 were prospectively enrolled. Patients undergoing surgery for instability due to trauma were excluded. Patients completed questionnaires (SF- 36, NDI, PROMIS PI and PF Computer administered tests [CAT]) preoperatively. Demographic data, presenting complaint, and procedures were recorded. Correlation and regression analyses were performed to define levels of severe disability and to determine formulas converting PROMIS PF and PI scores to SF- 36 PCS and NDI. Results: 196 patients met our inclusion criteria. The average age was 56.9 ± 12.9 years. The mean preoperative NDI score was 34.3±19, PCS was 51.6±19, PROMIS-PI was 60.9±7.3 and PROMIS-PF was 41.2±7.8. Scores were normally distributed as confirmed by the Komogorov-Smirnov test (p>0.05 for all variables). PROMIS PI was strongly correlated to NDI (r=0.76, p<0.001),and PROMIS PF was strongly correlated to PCS (r=0.079, p<0.001). Linear regression revealed the following formulas: PROMIS PI = 50.147 - 0.259*NDI (R2 = 0.57), PROMIS PI = 71.782 - 0.210*PCS (R2 = 0.31) PROMIS PF = 50.147 - 0.259*NDI (R2 = 0.40), PROMIS PF = 25.016 + 0.314*PCS (R2= 0.62) Conversion tables were constructed using the formulas above. Using an NDI score of 40 as a cut-off for severe disability, we found that PROMIS PI score of 62.6 or greater was correlated with significant disability. A reference table was constructed to convert SF-36 scores for various chronic conditions to PROMIS- PF and PI scores. Conclusions: We performed regression analysis enabling conversion of PROMIS PI and PF scores to NDI and SF-36 PCS. PROMIS PI was most strongly correlated to NDI, while PROMIS PF was most strongly correlated to PCS. A PROMIS PI score greater than 63 was correlated to substantial disability (NDI=40). These results provide valuable reference as PROMIS reporting becomes more widespread in the literature. Disclosures: M. Steinhaus: None. F. Lovecchio: None. L. Barber: None. K. Shafi: None. D. Stein: None. T. Ross: None. J. Yang: None. T. Albert: A; Saunders/ Mosby-Elsevier, Thieme. D; ASIP, Biometrix, Breakaway Imaging, Crosstree, FacetLink, Gentis, In ViVo Therapeutics, Invuity, Paradigm Spine, PMIG, Spinicity, Vertech. F; Biomet, DePuy, A Johnson & Johnson Company, Jay Pee, Saunders/Mosby-Elsevier, Thieme. D. Lebl: B; K2M, Nuvasive. D; Woven. R. Huang: None. B. Rawlins: None. F. Schwab: A; DePuy, A Johnson & Johnson Company, Nuvasive, Stryker. B; Globus Medical, K2M, Medicrea, Medtronic, Zimmer. C; K2M, Medtronic Sofamor Danek, Zimmer. F; K2M, Medtronic Sofamor Danek, Zimmer. V. Lafage: A; DePuy, A Johnson & Johnson Company, Medtronic, Nuvasive, Stryker. B; Globus Medical. C; DePuy, A Johnson & Johnson Company, K2M. D; Nemaris Inc. H. Kim: A; ISSGF. F; K2M, Zimmer. Paper #44: Two-Year Retrospective Bayesian Assessment of Cervical Artificial Disc Replacement Failure Factors Amir Vokshoor, MD; Vance Matthews, BA; Sophia Mostowy, BA; Johny Tran, BA; and Hyun Bae, MD Institute of Neuro Innovation, Santa Monica, CA Introduction: Previous cervical artificial disc replacement (C-ADR) research has not applied Bayesian methods to measure the associations between demographic and perioperative factors and C-ADR failure in small populations. Aims/Objectives: The objective of the study was to determine if associations exist between demographic and perioperative variables and C-ADR failures, defined as reoperations on or adjacent to the C-ADR’s index within 2 years. Methods: A neurosurgical population of C-ADR patients' demographic and perioperative data were retrospectively collected from 2013 to 2017. Associations between the variables were analyzed through univariate and multivariate Bayesian logistic regressions. Results: Fifty patients were identified as having either a C-ADR (n=28, 56%) or hybrid (C-ADR and fusion; n=22, 44%) surgery; 18% (9/50) were C-ADR failures. In the univariate analysis, the most positively associated factors with C-ADR failure were single marital status and C-ADR height >5 mm; 90% credible intervals over the log odds ratio (CI) were (0.09-2.71) and (0.27- 2.91), respectively. The most negatively associated factors were depression (90% CI, −2.24 to −0.68) and divorced marital status (90% CI, −5.62 to −0.36). Current smoking (90% CI, −0.04 to 3.15), non-white race (90% CI, −0.16 to 2.77), and >1-2 year symptom duration (90% CI, −0.33 to 2.55) trended positively with C-ADR failure, while length of stay (90% CI, −1.78 to 0.11) trended negatively. In the multivariate analysis, the most positively associated factors with C-ADR failure were non-white race (90% CI, 0.05-0.66), single marital status (90% CI, 0.03-0.55), and current smoking (90% CI, 0.20-0.83). Having depression (90% CI, −0.61 to −0.05) and being an older male (90% CI, −0.22 to −0.01) were negatively associated with C-ADR failure. Previous spine CONCURRENT SESSION 2C: YOUNG SURGEONS’ FREE PAPERSAbstracts AnnualForum’19 36ANNUAL FORUM ’19 | LAS VEGAS, NEVADA | OCT. 31–NOV. 2, 2019 surgery (90% CI, −0.08 to 0.45), former smoking (90% CI, −0.02 to 0.55), and hybrid surgery (90% CI, −0.05 to 0.46) trended positively with C-ADR failure, while workers compensation (90% CI, −0.58 to −0.04) trended negatively. Conclusions: In a small sample size, Bayesian methods were able to capture the range of certainty of associations between demographic and perioperative variables and C-ADR failure; however, distinguishing whether associations were patient selection biases for reoperation or real effects is undetermined. Future research will investigate models that can account for these potential biases with multiple surgeons. Disclosures: A. Vokshoor: A; Aegis Spine, Orthofix, Stryker K2M. B; Globus Medical. V. Matthews: None. S. Mostowy: None. J. Tran: None. Paper #45: The Impact of NSAID Use After Lumbar Fusion Surgery on Fusion Rate and Complications: A Meta-Analysis Yahya Othman; Abduljabbar Alhammoud, MD; Avani Vaishnav, MBBS; Catherine Himo Gang, MPH; Steven McAnany, MD; Sravisht Iyer, MD; Todd Albert, MD; and Sheeraz Qureshi, MD, MBA Hospital for Special Surgery, New York, NY Introduction: The purpose of this study is to compile data presented in the literature regarding the efficacy of incorporating NSAIDS in the postoperative course for patients undergoing spine surgery. In particular, NSAIDs impact on pain levels, opioid use, complications, and hospital length of stay. Methods: This is a meta-analysis and systematic review. A literature search was conducted using the backbone search [spinal surgery] [NSAID] [complications]. Criteria for inclusion were: use of NSAIDs for postoperative pain management after spinal surgery, comparison between NSAID and NSAID-free cohort, and reporting on any of pain scores, hospital opioid use, hospital length of stay, complications rate, and operative outcomes. Results: Out of 799 studies, 19 studies met the inclusion criteria. A total of 1522 patient were included in this analysis. The studies included randomized controlled trials, including prospective and retrospective cohorts. Operations included discectomies, laminectomies, and fusions. Most commonly regimens included the NSAID ketorolac, as in injection given immediately postoperatively. Patients that received NSAID analgesia postoperatively had significantly lower VAS pain scores at 1-hour and 12-hours postoperatively. This group also had a significantly lower opioid consumption and shorter hospital length of stay. Seven fusion studies reported on arthrodesis, showing a significantly lower odds of fusion after NSAIDs use, however after subgrouping according to smoking, this difference proved to be no longer significant. Conclusions: Incorporation of NSAIDs into the postoperative regimen for analgesia in patients undergoing spine surgery is an effective approach in reducing hospital length of stay, patient reported pain scores, hospital opioid use, and has no increased risk of complications. Furthermore, use of NSAIDs in the non- smoking population does not seem to affect arthrodesis rates in patients undergoing spine surgery. Disclosures: Y. Othman: None. A. Alhammoud: None. A. Vaishnav: None. C. Gang: None. S. McAnany: None. S. Iyer: None. T. Albert: None. S. Qureshi: None. Paper #46: Preoperative Opioid Use and Postoperative Pain in Patients Undergoing Minimally Invasive Stand-Alone Lateral Lumbar Interbody Fusion Alp Ozpinar, Medical Doctor; Nima Alan, MD; Nitin Agarwal; David Okonkwo, MD; Kojo Hamilton, MD; and Adam Kanter, MD University of Pittsburgh Medical Center, Pittsburgh, PA Introduction: Opioid use in management of pain secondary to spinal disorders has grown significantly in the US. There is present concern that preoperative opioid use may complicate recovery in patients undergoing surgical procedures, presenting risks beyond that of opioid dependence. We hypothesized that prolonged preoperative opioid use may lead to poorer patient outcomes following minimally invasive lateral lumbar interbody fusion (MIS LLIF) for lumbar degenerative disc disease. Aims/ Objectives: Outcomes in spine surgery may benefit from preoperative optimization of medical comorbidities, nutritional status, and weight management. With increasing concern over prescription opioid dependence for chronic conditions, the aim of this study is to evaluate whether postoperative outcomes are linked to preoperative opioid dependence following lateral lumbar interbody fusion. Methods: A consecutive series of patients from a single institution undergoing MIS LLIF between December 2009 and January 2017 was retrospectively analyzed. Patients were categorized according to the presence or absence of prescribed preoperative opioid use. Standard oral morphine dose- equivalents were computed using the opioid dose calculator CONCURRENT SESSION 2C: YOUNG SURGEONS’ FREE PAPERSAbstracts AnnualForum’19 37ANNUAL FORUM ’19 | LAS VEGAS, NEVADA | OCT. 31–NOV. 2, 2019 developed by the Washington State Agency Medical Directors' Group. Outcomes included the Oswestry Disability Index (ODI), Visual Analogue Scale (VAS), and Short Form 36 Physical and Mental Summary Scores (SF36-PCS, SF36-MCS). Between-cohort comparisons were performed with independent samples t-test. Results: Of 107 patients with an average of 2 ± 1 levels treated, 57 (53.1%) were prescribed preoperative opioids, with a mean oral morphine milligram equivalent (MME) of 26.6 ± 36.3 mg/ day. Patients were followed for 11.4 ± 7.8 months. There was no significant difference in preoperative ODI, VAS score, SF- 36 PCS, and SF-36 MCS between opioid use groups. Mean postoperative ODI was greater in patients with preoperative opioid use at 41.7 ± 16.9 versus 22.2 ±16.0 (p=0.002). Mean postoperative VAS score was greater in patients prescribed preoperative opioids while magnitude of decrease in VAS score was greater in opioid-naïve patients (p=0.001). Postoperative SF-36 PCS was 33.1 ± 10.6 in the opioid use group compared to 43.7 ± 13.1 in the non-use group (p=0.001). Conclusions: In this single center consecutive series of lumbar degenerative disc disease patients undergoing MIS LLIF, patients prescribed preoperative opioids had increased postoperative lumbar pain, disability, and subjective pain report compared to patients not prescribed preoperative opioids. Disclosures: A. Ozpinar: None. N. Alan: None. N. Agarwal: None. D. Okonkwo: None. K. Hamilton: None. A. Kanter: None. Paper #46b: Lumbar Microdecompression in Elderly Versus General Adult Patients: Comparable Outcomes Despite Group Differences Ziyad Knio, BS; Samuel Rosas, MD; Michael Schallmo, BS; and Tadhg O'Gara, MD Wake Forest School of Medicine, Winston-Salem, NC Introduction: Rates of lumbar spine surgery in the United States have increased considerably, particularly in the Medicare population. Moreover, minimally invasive techniques are increasingly selected over traditional approaches. Given this trend, it is important to consider whether differences exist in microdecompression outcomes between elderly and general adult patients. Aims/Objectives: This study investigates differences between patients under 65 and patients 65 and older following microdecompression for symptomatic lumbar spinal stenosis. Patient characteristics, surgical outcomes, and patient-reported outcome measures (PROMs) over a 2-year follow-up period are reported. Methods: The senior author’s microdecompression case log between January 2014 and June 2017 was reviewed. All living patients were included. PROMs included Visual Analog Scale (VAS) back pain and leg pain , Oswestry Disability Index (ODI), and EuroQol Five Dimensions (EQ-5D). PROMs were collected preoperatively and at 1-year intervals as standard-of-care. Two age groups were defined: patients under 65 and patients 65 and older. Differences between age groups were investigated with a t-test for continuous data and a chi-square test for categorical data. A linear mixed effects model was fit to PROMs; pairwise Tukey comparisons were used to assess improvement at 1- and 2- years and investigate whether age had an effect. Results: A total of 144 patients were included in this study (67 patients under 65, 77 patients 65 and older). Gender, obesity, tobacco use, and history of spine surgery were equally represented in the 2 groups. Length of hospital stay and revision rates were comparable between the 2 groups. Patients under 65 were more likely to require discectomy (21/67 vs. 3/77, p<0.001). Patients 65 and older were more likely to have diabetes (24/77 vs. 8/67, p=0.006) and require multi-level decompression (9/77 vs. 2/67, p=0.050). Despite patients under 65 having greater preoperative ODI (56.93 ± 14 vs. 46.37 ± 19.53, p=0.005) and 1-year back pain VAS (3.66 ± 3.18 vs. 2.43 ± 2.61, p=0.017), there was no difference in any 2-year PROMs between the 2 age groups. A linear mixed effects model confirmed improvement in PROMs at 1- and 2- years. Age had a significant effect on back pain improvement (p=0.016), but not on leg pain (p=0.377), ODI (p=0.063), or EQ-5D (p=0.138) improvement. Conclusions: Microdecompression is an effective treatment option for symptomatic lumbar spinal stenosis in both elderly and general adult populations. Pain, disability, and health state are comparable at 2-years post-operatively, despite differences between age groups. Disclosures: Z. Knio: None. S. Rosas: None. M. Schallmo: None. T. O'Gara: None. CONCURRENT SESSION 2C: YOUNG SURGEONS’ FREE PAPERSAbstracts AnnualForum’19 38ANNUAL FORUM ’19 | LAS VEGAS, NEVADA | OCT. 31–NOV. 2, 2019 Paper #47: Reoperation and Complication Rates After Strategic Circumferential Minimally Invasive Surgical (cMLS) Correction of Adult Spinal Deformities (ASD): A 7-Year Study Neel Anand, MD; Babak Khandehroo, MD; Sheila Kahwaty, PA-C; and Edward Nomoto, MD Cedars Sinai Medical Center, Los Angeles, CA Introduction: Several studies have shown that postoperative complications and reoperation rate represent an important measure of quality and cost-effectiveness of care in any surgery. However, there is little information about the readmission following the new strategic staged minimally invasive surgical (MIS) correction of ASD. Aims/Objectives: This study was conducted to assess reoperation and complication rate after cMIS correction of ASD. Methods: This is a retrospective review of prospectively collected data registry of 211 patients who underwent cMIS correction of ASD (Cobb angle>20 or SVA>50 mm or PI/LL mismatch>10) from May 2011 to August 2018. Minimum of 1-year follow-up, fusion of 3+ levels included 171 patients for this study. In all patients, multilevel oblique LLIF±L5-S1 OLIF/ALIF was done in the first stage. The patients were ambulated after a standing radiograph obtained 2 days later and further correction of alignment was planned for the second stage accordingly. Three days later MIS pedicle screws with aggressive rod contouring and derotation/translation was done. Postoperative complications and reoperation rates were collected and statistically analyzed. Results: The mean age of patients was 65 years (range, 21- 85). Mean follow-up was 54 months (range, 12-98). A total of 1174 levels were fused with an average of 7 levels (3-16) per patient. Mean hospital stay was 8 days(range, 2-26). The 30- day postoperative complication rate was 4.7% (n=8) including: 2 during surgery, 3 during hospital stay, 1 in the second week, and 2 in the third week postoperatively. Out of these 6 complications, 5 patients needed corrective/revised operation during initial hospitalization: 1 with incidental durotomy and CSF Leak, 1 with avulsed segmental arterial branch, 2 with uretero- pelvic junction injury, and 1 with misplaced screw. Within 30 days after index surgery, 3 patients needed readmission: 2 patient with hardware displacement and 1 patient with malaligned hardware. Overall 30-day readmission rate was 1.7% (n=3). After 30 days, there were 26 complications including: 5 adjacent segment degeneration, 5 hardware failure, 1 misplaced screw, 3 painful hardware (prominent Hardware), 3 PJK, 7 pseudarthrosis, and 2 stenosis. The complication rate was 3.5% (n=6) in first 6-month postop , 2.3% (n=4) in 6-12 months, 5.2% (n=9) in 1-2years postop, 2.3% (n=4) in 2-3 years postop, and 1.7% (n=3) in 3 to 5 years postoperative post-op. Conclusions: Our study delivers significant evidence that effort to reduce hospital readmissions for ASD patients should begin by concentrating on postoperative complications. cMIS approaches will not eliminate all postoperative readmissions but will likely have a major effect on dropping complication rates which could result in a substantial reduction in readmissions. Disclosures: N. Anand: B; Medtronics, Globus Medical, GYS Tech. C; Depuy Synthes, Stryker K2M. D; Medtronics, Globus Medical, Atlas Spine, Paradigm Spine, TheraCell, GYS Tech. F; NuVasive, Medtronics, Globus Medical. B. Khandehroo: None. S. Kahwaty: None. E. Nomoto: None. Paper #48: Revision Surgery Rates in Patients Undergoing Minimally Invasive Adult Spinal Deformity Surgery: Is There a Correlation with Roussouly Spine Type? Dean Chou 1 ; Pierce Nunley 2 ; Robert Eastlack 3 ; Juan Uribe 4 ; Richard Fessler 5 ; Khoi Tran 6 ; Paul Park 7 ; Kai-Ming Fu 8 ; Michael Wang 9 ; Adam Kanter 10 ; David Okonkwo 11 ; Neel Anand 12 ; Gregory Mundis 13 ; and Praveen Mummaneni 14 University of California, San Francisco, CA 1 ; Spine Institute of Louisiana, Shreveport, LA 2 ; Scripps Clinic, San Diego, CA 3 ; University of South Florida, Tampa, FL 4 ; Rush University Medical Center, Chicago, IL 5 ; Oregon Health & Science University, Portland, OR 6 ; University of Michigan, Ann Arbor, MI 7 ; Weill Cornell Medical Center, New York, NY 8 ; University of Miami, Miami, FL 9 ; University of Pittsburgh Medical Center-Presbyterian, Pittsburgh, PA 10 ; University of Pittsburgh, Pittsburgh, PA 11 ; Cedars-Sinai Spine Center, Los Angeles, CA 12 ; Scripps Clinic Medical Group, Department of Orthopedics, La Jolla, CA 13 ; and University of California, San Francisco, San Francisco, CA 14 Introduction: Correction for adult spinal deformity (ASD) has long been achieved with re-alignment of spinal balance. Traditional spinopelvic parameters have been used to evaluate ASD, but the Roussouly classification is an increasingly utilized alternative method. Aims/Objectives: Spinopelvic parameters have been used to predict construct failure and revision surgery rates. We investigate if revision surgery rates may be predicted based upon the Roussouly spinal classification. Methods: A retrospective, multicenter database review of North American ASD centers that performed circumferential minimally invasive surgery (cMIS) ASD with minimum 2-year CONCURRENT SESSION 8A: DEFORMITY & CERVICAL FREE PAPERSAbstracts AnnualForum’19 39ANNUAL FORUM ’19 | LAS VEGAS, NEVADA | OCT. 31–NOV. 2, 2019 follow-up. Inclusion criteria were age ≥18 years, and one of the following: coronal cobb >20, SVA >5 cm, PT >20, PI-LL >10. Patients were categorized into 4 groups based on Roussouly classification. Preoperative and postoperative measures were analyzed, including pelvic incidence (PI), lumbar lordosis (LL), Cobb angle, sagittal vertical axis (SVA), complications, reoperation rates for index surgery, reoperation rates for adjacent segment degeneration, and reoperation rates for proximal junctional kyphosis (PJK). Results: Patients were classified as Type I (41 patients); Type II (32 patients); Type II (23 patients); Type IV (8 patients). Preoperatively, Type IV patients had the highest PI (Type I: 50°, II: 50°, III: 55°, IV:66°, p=0.002) and LL (Type I: 39, II: 27, III: 48, IV: 56, p<0.001). The preoperative PI/LL mismatch was highest in Type II (I: 11, II: 24, III: 7, IV: 9). Postoperatively, PI/LL mismatch, Cobb angle, and SVA were not statistically different among the 4 groups. Reoperation rates for the index surgery were comparable between all groups (I: 19.5%, II: 38.7%, III: 13.0%, IV: 12.5%, p=0.097). The reoperation rates were also comparable for adjacent segment degeneration (p=0.204) and proximal junctional kyphosis (p=0.060). Complications were statistically higher for Type II patients (I: 29.3%, II: 61.3%, III: 34.8%, IV: 25.0%, p=0.031). Conclusions: ASD patients with preoperative Roussouly Type II experienced the highest rate of post-operative complications (mainly minor and radiographic) following cMIS. There was no correlation between Roussouly type and rate of revision surgery. However, this study may be underpowered to detect a statistical difference. Disclosures: D. Chou: B; Globus Medical, Medtronic. F; Globus Medical. P. Nunley: 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; Stryker K2M, Zimmer Biomet, Camber Spine, Integrity Spine. R. Eastlack: A; NuVasive. B; Aesculap/B.Braun, Baxter, Stryker K2M, NuVasive, SeaSpine, SI Bone. C; Radius. D; Alphatec Spine, Carevature, Invuity, Nocimed, NuVasive, SeaSpine. F; Globus Medical, NuVasive, SeaSpine, SI Bone. J. Uribe: A; NuVasive. B; Misonix, NuVasive, SI Bone. C; NuVasive. D; NuVasive. F; NuVasive. R. Fessler: B; DePuy Synthes. C; Benvenue, Inc. F; DePuy Synthes. K. Tran: B; Bioventus. P. Park: A; Pfizer, Vertiflex. B; Allosource, Globus Medical, Medtronic, NuVasive. F; Globus Medical. K. Fu: None. M. Wang: B; DePuy Synthes, A Johnson & Johnson, Globus Medical, Stryker K2M, Spineology. C; Children’s Hospital of Los Angeles, Depuy Synthes, Globus Medical, Springer Publishing. D; Innovative Surgical Devices. F; DePuy Synthes, A Johnson & Johnson, Quality Medical Publishing. A. Kanter: A; NuVasive. F; NuVasive, Zimmer Biomet. D. Okonkwo: F; Zimmr Biomet, NuVasive. N. Anand: B; Medtronic. C; Globus Medical, Medtronic. D; Atlas Spine, Medtronic, Paradigm, Theracell, Globus Medical, GYS Tech. F; Elsevier, Globus Medical, Medtronic. G. Mundis: A; ISSGF, NuVasive. B; Stryker K2M, NuVasive. C; DePuy Synthes, A Johnson & Johnson, Stryker K2M, NuVasive. F; Stryker K2M, NuVasive. P. Mummaneni: A; ISSGF, NREF. B; DePuy Synthes, A Johnson & Johnson, Globus Medical,. C; AO Spine, SpineArt. D; Spinicity. F; DePuy Synthes, A Johnson & Johnson, Springer, Taylor and Francis, Thieme. Paper #49: Are The New Strategic Circumferential Minimally Invasive Surgical Techniques a Safe and Effective Approach for Correction of Adults Spinal Deformity in Elderly Patients? Neel Anand, MD; Edward Nomoto, MD; Babak Khandehroo, MD; and Sheila Kahwaty, PA-C Cedars Sinai Medical Center, Los Angeles, CA Introduction: Recently the new strategic staged circumferential minimally invasive surgery (cMIS) approach for the correction of adult spinal deformity (ASD) has helped fine tune and sequentially correct sagittal misalignment. Implementing several changes to our original approach has made it a very attractive technique in elderly population. However, the impact of age on operative outcomes after these cMIS corrections has not been well studied. Aims/Objectives: To analyze clinical and radiologic outcomes of elderly patients who underwent cMIS correction for ASD. Methods: This is a retrospective study from a registry database of all patients who underwent cMIS correction of ASD (Cobb angle >20 degrees or SVA >50 mm or PI/LL mismatch >10) from May 2011 to August 2018. The inclusion criterial included a minimum of 1-year follow-up, fusion of 3+ levels, having preop and postop 36” scoliosis films, and having age >69 years. A total of 76 patients were included in study. In all patients, multilevel oblique LLIF±L5-S1 OLIF/ALIF was done in the first stage. The patients were ambulated after a standing radiograph obtained 2 days later and further correction of alignment was planned for the second stage accordingly. Three days later, MIS pedicle screws with aggressive rod contouring and derotation/ translation was done. Results: Mean age was 74 years (range, 70-85). Mean follow- up was 53 months (range, 12-98). Total of 502 levels fused with mean of 7 levels (range, 3-16) per patient. The mean blood loss and surgical time was 345 mL(range, 50-1700) and 262 minutes (range, 91-551) for the stage 1 and 410 mL (range, 50- 2000) and 266 minutes (range, 71-550) for the stage 2 group, respectively. Mean baseline HRQOL scores (VAS: 7 (2-10, SD 2), ODI: 47 (24-71, SD 13.8) were significantly decreased at the CONCURRENT SESSION 8A: DEFORMITY & CERVICAL FREE PAPERSNext >