Search

BACKGROUND CONTEXT Robot-guided lumbar instrumented fusion (RGLF) for accurate pedicle screw placement is increasingly popular. Learning curve (LC) has been reported to be short, but simple comparison of a set number of early to later cases may oversimplify the LC. This study offers an analysis of a single institution LC for RGLF as it relates to increasing case complexity as determined by Spine Surgical Invasive Index (SII) as described by Mirza, and advanced techniques. PURPOSE To determine if RGLF is related to SII and is more dynamic than previously described. STUDY DESIGN/SETTING Single-center retrospective cohort study. PATIENT SAMPLE A total of 346 patients undergoing RGLF at a single institution from 2018 to 2021. OUTCOME MEASURES Case complexity indicators (levels fused, SII, iliac fixation, single position surgery), radiation dose, procedure/operative time (PTime/OpTime), EBL, LOS, failed registration, robotic mechanical failures, perioperative complications and OR returns. METHODS All RGLFs at a single institution were included. Outcome measures indicating case complexity (levels fused, SII, iliac fixation, single position surgery) underwent regression analysis to determine risk factors for robot-related complications. Peaks in these characteristics over the course of 346 cases were identified. Outcomes including radiation dose, procedure/operative time (PTime/OpTime), EBL, LOS, failed registration, robotic mechanical failures, perioperative complications, and returns to OR were analyzed in stepwise fashion by each consecutive case using independent samples t-tests and chi-squared analyses as appropriate. RESULTS A total of 346 RGLFs included. No significant changes in demographics over time. SII was an independent risk factor for robot registration and intraoperative mechanical failures on multivariate regression analysis (p CONCLUSIONS Two learning curves were observed that mirrored significant peaks in SII. The second, more significant, wave of complications was observed with increased surgical complexity. This suggests a longer, more dynamic learning curve than has been previously described. Avoiding surgeries with high SII at the beginning of RGLF experience may prevent early complications. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

BACKGROUND CONTEXT Patients with diabetes mellitus (DM) undergoing posterior spinal fusion (PSF) with elevated HbA1cs are at higher risk of postoperative complications than those with lower HbA1cs. DM patients with an HbA1c >7.05% are prone to postoperative complications such as wound complications (WC). Pseudarthrosis (PA) is another complication for PSF and requires further insight in determining risk factors for DM. PURPOSE To determine if DM patients with higher preoperative HbA1c levels will have higher rates of WC and PA. STUDY DESIGN/SETTING Single-center retrospective cohort study. PATIENT SAMPLE This study included 229 DM patients. OUTCOME MEASURES Patient demographics, osteopenia, preoperative HbA1c, WC, PA, and levels-fused (LF). METHODS Included: DM patients undergoing thoracolumbar PSF from 2014-2019 with preoperative HbA1C levels, and a minimum 1-year postoperative follow-up. PA was defined by the treating surgeon via clinical presentation, radiographs and postoperative CT scan with minimum 1-year postoperative interval. WC included dehiscence, seroma requiring aspiration or infection of the surgical site. Excluded: Patients undergoing LLIFs and ALIFs or diagnosed with prior pars fracture, spinal tumor, ankylosing spondylitis, fracture and infection. Relationships between complications and HbA1c were determined using t-test, chi-squared analyses and multivariate regressions (α=0.05). In risk factors, the cutoff HbA1C value as a predictor for multiple postoperative complications was identified via receiver operating characteristic (ROC) analyses using Youden's index. RESULTS A total of 229 patients met these criteria. Age (Normal: 65.4±11.0, PA: 63.0±8.2, p=0.249; Normal: 65.2±10.6, WC: 64.5±9.7, p=0.753), CCI (Normal: 4.6±2.0, PA: 4.0±1.2, p=0.06; Normal: 4.6±1.9., WC: 4.6±1.7, p=0.761), gender, percent female, (Normal: 57%, PA: 47%, p=0.286; Normal: 55%, WC: 58%, p=0.829), osteopenia (Normal: 3%, PA:3%, p=0.968; Normal: 3%, WC: 0.0%, p=0.377), and smoker status (Normal: 11%, PA: 16%, p=0.44; Normal: 11%, WC: 12%, p=0.915) did not have a significant impact in the tested postoperative complications. Mean HbA1c (7.6±1.5%, p=0.001), LF (3.9±3.2, p=0.024) and BMI (35.8±7.4, p=0.004) in patients with WC were significantly higher than those without WC (HbA1C: 6.8±1.0%; LF: 2.5±2.9 BMI: 31.7±6.7). HbA1c (OR: 1.7 [1.2-2.5], p=0.005), BMI (OR: 1.1 [1.0-1.2], p=0.007) and LF (OR: 1.1[1.1-1.3], p=0.031) was an independent risk factor WC. In those with PA, mean HbA1c (7.0±1.3, p=0.289) was not significantly higher than those without PA (HbA1C:7.0±1.1). HbA1c (OR: 1.039 [0.73-1.478], p=0.831) was not an independent risk factor for PA.ROC analyses demonstrated HbA1c>7.05% (AUC: 0.693[0.587-0.800], p=0.001], BMI>32.92 (AUC: 0.664[0.555-0.772], p=0.007) and >1.5 LF (AUC: 0.626[0.502-0.750], p=0.036) as fair predictive models for WC. CONCLUSIONS Preoperative HbA1C>7.05%, BMI>32.92 and LF>1.5 are independent risk factors of WC; however, neither of these are predictors for PA in diabetics who had PSF. Regardless, DM patients undergoing PSF should strive to lower their HbA1c FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

BACKGROUND CONTEXT Robot-guided lumbar instrumented fusion (RGLF) has the potential to improve safety and accuracy of pedicle screw placement. However, there are pitfalls in adopting this new technology and, as in adopting any new OR technology, there may be early complications. Optimizing workflow by avoiding interbody placement prior to pedicle screws placement (interbody-first workflow, IFW) and using caution in patients with poor bone quality (L1 Hounsfield units [HU] under 148) may improve outcomes. PURPOSE To determine risk factors for robot-related complications and suggest optimal OR workflow. STUDY DESIGN/SETTING Single-center retrospective study. PATIENT SAMPLE A total of 344 RGLF cases from 2018 to 2021. OUTCOME MEASURES L1 and UIV HU, levels fused, L5-S1 inclusion, interbody placed first workflow (IFW), hyperlordotic interbody, robot registration method, robot registration failure, intraoperative robot mechanical failures and pedicle screw malpositioning. METHODS Retrospective analysis of RGLFs at a single institution. Univariate analysis with t-tests, Mann-Whitney U tests, or chi-squared analysis assessed demographics, L1 and UIV HU, levels fused, L5-S1 inclusion, IFW, hyperlordotic cage, and robot registration method as risk factors for robot registration failure, intraoperative robot mechanical failures, and pedicle screw malpositioning. Multivariate logistic regression of risk factors approaching or achieving significance was conducted. A receiver operating characteristic (ROC) curve was created to determine a threshold for independent risk factors. RESULTS A total of 344 RGLFs were included. In registered vs registration failure cases, smoking (12.73% vs 28.57%; p=0.041), L1HU (139.81±46.86 vs 177.16±55.74; p=0.009), L5-S1 inclusion (50.00% vs 80.95%; p=0.006), and IFW (58.07% vs 85.71%; p=0.014) were significant risk factors on univariate analysis. On multivariate analysis, smoking (p=0.003), L1HU (p=0.006), and L5-S1 inclusion (p=0.022) were independent risk factors and IFW approached significance (p=0.099) for risk of registration failure. In successful vs all robot failures cases, age (55.72±13.38 vs 59.92±11.38 years; p=0.046), female gender (48.70% vs 69.44%; p=0.018), levels fused (1.37±0.63 vs 1.67±0.76; p=0.010), L5-S1 inclusion (50.00% vs 69.44%; p=0.027), and IFW (57.47% vs 77.78%; p=0.012) were significant risk factors on univariate analysis. On multivariate analysis, female gender (p=0.047) and L5-S1 inclusion (p=0.049) were independent risk factors and IFW approached significance (p=0.055) for risk of mechanical failure. In successful vs pedicle screw malpositioned cases, IFW was a significant independent risk factor for pedicle screw malpositioning on multivariate analysis (p=0.038). On subanalysis of 124 robot-guided anterior-posterior lumbar fusion (RG APLF), L1 HU was an independent risk factors for registration failure (p=0.007) and approached significance for mechanical failures (p=0.051). ROC analysis revealed a cutoff of L1 HU of 148.55 for mechanical failures (area under the curve = 0.778). Levels fused (1.41±0.69 vs 2.00±0.54; p=0.018) was a significant risk factor for pedicle screw malpositioning on univariate analysis. CONCLUSIONS In all RGLFs, IFW was a risk factor for robot-related complications. In RG APLF, low L1 HU was a risk factor. Robot-related complications may be avoided by placing pedicle screws prior to interbody and by using caution in patients with poor bone quality. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

BACKGROUND CONTEXT The inter-relationship between the hip and spine has been increasingly studied in recent years, particularly as it pertains to the effect of spinal deformity and hip osteoarthritis (OA). Changing from standing (ST) to seated (SE) requires rotation of the femur from an almost vertical plane to the horizontal. OA of the hip significantly limits hip extension, resulting in less ability to recruit pelvic tilt (PT) in ST, and requiring increased PT in SE to compensate for loss of hip flexion. To date, the effect of total hip arthroplasty (THA) in altering spinopelvic SE and ST mechanics has not been reported. PURPOSE To investigate the change in spinopelvic alignment parameters between seated and standing positions in pre and post THA patients. STUDY DESIGN/SETTING Retrospective review at a single academic institution. PATIENT SAMPLE Adult patients undergoing THA with full body sitting and standing radiographs pre- and post-THA. OUTCOME MEASURES Spinopelvic alignment measures including pelvic incidence (PI), pelvic tilt (PT), T1 pelvic angle (TPA), sacral slope (SS), sagittal vertical axis (SVA), pelvic incidence and lumbar lordosis mismatch (PI-LL), and lumbar lordosis (LL). METHODS Patients ≥18yo undergoing THA for hip OA with full spine SE and ST radiographs pre and post THA were included. Spinopelvic alignment was analyzed pre-THA and post-THA in both ST and SE positions in a relaxed posture with the fingers on the clavicles. Paired t-test analysis was performed to compare Pre-and Post-THA groups. The effect of TL deformity (SVA>50, TPA>20, PI-LL>10) on these changes was also analyzed. Statistical significance set at p RESULTS There were 192 patients assessed. 179 patients had thoracolumbar (TL) deformity; TPA>20 (N=46), PI-LL>10 (N=55), and SVA>50 (N=78). In standing position, patients have a significant reduction in SVA post THA vs pre THA (34.09±42.69 vs 45.03±46.87, p=0.001) as a result of an increase in PT (15.7±9.74 ᵒ vs 14.6±9.88ᵒ,p=0.028), without significant changes in spinal alignment parameters including lumbar lordosis (-51.26±14.59 vs -50.26±14.87, p=0.092), thoracic kyphosis (35.98±12.72 vs 35.40±13.16, p=0.180), sacral slope (38.15±10.77 vs 38.83±11.31, p=0.205), T1 pelvic angle (14.22±9.94 vs 14.51±10.13, p=0.053) and PI-LL mismatch (2.59±14.61 vs 3.35±14.92, p=0.183). This change in ST_SVA was larger in patients with TL deformity, specifically in those with SVA>50 (61.29±45.69 vs 89.48±35.91, p=0.001), in PI-LL > 10 (59.08±45.49 vs 73.36±48.50, p=0.001) and in TPA>20 subsets (62.14±49.94 vs 82.28±49.55, p=0.001). When moving from ST to SE, the ΔPT was reduced post THA (16.70±15.27ᵒ vs 20.85±17.27ᵒ, p=0.001) in addition to a smaller SE_PT vs pre-THA (32.41±14.47 vs 35.46±14.20, p=0.006). CONCLUSIONS Post Total Hip Arthroplasty (THA), patients demonstrated an increased recruitment of pelvic retroversion to achieve a better global balance by reduction in standing SVA. This compensation was achieved solely by greater mobility of their hip and pelvis, and without a significant change in spinal alignment. ST_SVA reduction was more pronounced in patients with thoracolumbar (TL) spinal deformity (SVA>50, TPA>20, PI-LL>10). On the converse, PT was reduced in sitting (SE) post-THA compared to pre-THA, and the compensatory change in PT was also reduced between ST and SE as a result of restoration of hip flexion. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

BACKGROUND CONTEXT History, physical exams (PE) and imaging are used to diagnose spine pathology. There is limited data on differences in telehealth physical exam findings when compared to in person physical examinations in the same patient. Further analysis is required to determine differences in telehealth visits (TV) and office visits (OV) examinations and the clinical significance of these differences. PURPOSE To determine differences in TV and OV examinations and the clinical significance of these differences. STUDY DESIGN/SETTING Single-center retrospective cohort study. PATIENT SAMPLE This study included 296 patients (247 surgical and 49 non-surgical). OUTCOME MEASURES Tibialis anterior (TA) deficit, hand grip (HG), hand intrinsic (HI), bilateral lower extremity motor deficits, bilateral upper extremity motor deficits, tandem gait (TG) abnormalities, straight legged raise (SLR) abnormalities, and extremity sensation (ES) abnormalities. METHODS Included: patients with spine pathologies who received an initial TV and a subsequent OV post-March 2020. Excluded: patients who received telehealth and office visit by two separate providers, providers outside of the spine service, or patients with an initial office visit in the timeframe. The cohort was further analyzed by pathologies. Motor exam results were categorized dichotomously as “full-strength: antigravity” or deficit and other physical exam findings were classified as abnormal and normal. False positives (FP) were classified as abnormalities detected only in TV and false negatives (FN) were categorized as abnormalities detected only in OV. Relationships between the TV and OV exam findings were established using chi-squared analyses (α=0.05). RESULTS The total cohort's average age is 56.5, BMI=28.6, and 50% female. Among the cohort, 8.9% of lumbar radiculopathy (LR) patients’ TV (w/ 5.1% being FP and 12.7% being FN) recorded a TA deficit, but 16.5% reported deficit in OV (p=0.048). Thus, TV either missed or falsely recorded 17.7% TA deficits. No deficits (0%) were recorded in both HG and HI in MY TV, but 12.5% and 15.6% had reported HG and HI deficits in OV, respectively. For tandem gait (TG), 21.9% MY (w/ 6.3% FP and 15.6% FN) patients’ TV reported an abnormal tandem TG, but in OV, 31.3% (p=0.009) reported abnormalities. For straight-leg raise (SLR), 16.5% LR (w/ 5.1% FP and 7.6% FN) reported abnormal SLR in TV but 13.9% had abnormalities in OV (p CONCLUSIONS TA, TG, SLR, and motor sensation have the highest rates of FP and NP in the spine telehealth examination. There should be a low threshold for an OV in the setting of equivocal testing. During a pandemic, surgeons should rely on the TV history/examination and imaging to make a diagnosis. OV is appropriate in cases in which an accurate TA, TG, SLR, and ES is required. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

BACKGROUND CONTEXT Complex surgery for adult spinal deformity has high rates of complications, reoperations, and readmissions. Multidisciplinary conferences have been shown to improve patient outcomes in many medical specialties but are not currently widespread in spine surgery. Preoperative discussions of high-risk operative spine patients at a multidisciplinary conference may decrease rates of these adverse outcomes through appropriate patient selection and surgical plan optimization. With this goal, we implemented a high-risk case conference involving orthopedic and neurosurgery spine, anesthesia, intraoperative monitoring neurology, and neurological intensive care on 2/19/2019. PURPOSE Examine rates of intraoperative and postoperative complications, readmissions, and reoperations in high-risk spine patients before and after the implementation of a multidisciplinary high risk case conference. STUDY DESIGN/SETTING Single institution retrospective review. PATIENT SAMPLE This study included 236 surgical adult spinal deformity patients who met one of the following criteria for presentation to the conference: 8+ levels fused, osteoporosis with 4+ levels fused, 3-column osteotomy, anterior revision of the same lumbar level, or severe myelopathy, scoliosis (>75˚), or kyphosis (>75˚) with planned significant correction. OUTCOME MEASURES Intra- and postoperative complications and 30- and 90-day readmissions and reoperations. METHODS Retrospective review was performed for the patient sample. Patients were categorized as Before Conference (BC): surgery before 2/19/2019 or After Conference (AC): surgery after 2/19/2019. Statistical analysis included independent samples t-tests and chi-squared analysis with significance set at p RESULTS A total of 236 patients were included (67 AC, 169 BC). AC was older than BC (60.2 vs 54.4, p =0.033), but had similar BMI (27.0 vs 29.0, p=0.061), CCI (3.27 vs 2.92 p=0.266), and ASA classification (2.5 vs 2.6, p=0.911). Surgical characteristics, including levels fused (10.4 vs 10.7, p=0.558), levels decompressed (1.5 vs 1.2, p=0.375), 3-column osteotomies (11.9% vs 18.3%, p=0.232), anterior column release (13.4% vs 12.4%, p=0.834), and revision cases (50.7% vs 52.4%, p=0.821) were similar between AC and BC. AC had lower EBL (1174.0 vs 1850.2, p=0.001), fewer intraoperative complications (17.9% vs 33.7%, p=0.016) and fewer delayed extubations (6.0% vs 22.5%, p=0.003). Length of stay was similar between groups (7.0 vs 8.1, 0.245). AC had a lower incidence of DVT/PE (0% vs 5.9%, p=0.042), but a higher rate of hypotension requiring vasopressor therapy (19.4% vs 4.7%, p=0.002). Other postoperative complications were similar between groups. AC had lower rates of reoperation at 30 (0% vs 8.9%, p=0.012) and 90 days (1.5% vs 12.4%, p =0.009). AC trended toward lower readmission rates at 30 (4.5% vs 10.7%, p =0.133) and 90 days (7.5% vs 15.4%, p=0.104). CONCLUSIONS Following implementation of a multidisciplinary high-risk case conference, 30- and 90-day reoperation rates and intraoperative complications decreased in the high-risk spine surgery population. Postoperative thromboembolic events decreased. Hypotensive events requiring vasopressors increased, but this did not result in a longer length of stay or greater readmissions. These results demonstrate the important role of this conference in improving quality and safety for high-risk spine patients. Multidisciplinary conferences should be considered to minimize complications and optimize outcomes in complex spine surgery. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

BACKGROUND CONTEXT Unconstrained cervical disc replacements prostheses (UCDR) have become more commonly used among surgeons performing cervical disc arthroplasty (CDA). CDR have favorable outcomes in treating cervical radiculopathy and restoring normative motion in the spine. More recently, UCDR have become popular due to their ease of insertion, however the unconstrained design's effect on segmental range of motion (ROM) has not been evaluated. PURPOSE To evaluate the unconstrained design's effect on segmental ROM. STUDY DESIGN/SETTING Single-center retrospective cohort study. PATIENT SAMPLE A total of 148 patients (58 single-level, 90 two-level). OUTCOME MEASURES Patient demographics, implant characteristics, baseline (BL) ROM, and follow-up ROM. Methods Patients diagnosed with cervical radiculopathy who underwent a primary 1- or 2- level UCDA from 2015-2019 with pre- and postoperative flexion-extension radiographs. Segmental sagittal measurements were taken to determine baseline (BL) and follow-up segmental ROM from the flex-extension views. Hypermobility was classified as ≥11.0° in ROM from BL to follow-up &/or >3mm translation. Mean BL and follow-up ROM were compared at each level using t-test analyses (α=0.05). Relationships between patient and implant demographics and hypermobility were determined using multivariate logistic regressions. Results A total of 148 (58 single-level, 90 two-level) patients met the criteria. Age, gender and BMI were similar between normal (Age: 42.7±8.7, gender [% female]: 41%, BMI: 28.1±5.5) and hypermobile groups (Age: 44.4±9.4, p=0.272; gender [% female]: 41%, p=0.98; BMI: 29.6±12.6, p=0.309); however, hypermobile patients (0.9±1.0) had a significantly higher CCI than the normal groups (0.4±0.8, p=0.003). Single-level patients: 23 (40%) developed hypermobility at follow-up. Follow-up ROM (12.2±6.8°, p=0.003) was significantly higher compared to the average BL ROM (9.2±4.9°). C5-C6 had significantly higher follow-up ROM (C5-C6: 13.7±6.9°, p=0.003) than BL ROM (C5-C6: 9.2±4.9°). Two-level patients: Although there was no significant difference between follow-up ROM (6.12±6.95°, p=0.749) and BL ROM (7.87±10.54°), 21(23.3%) cephalad and 20 (22.2%) caudal implants developed hypermobility postoperatively. Multivariate regression analysis of implant factors, patient demographics and disc level demonstrated no risk factors for hypermobility except a slightly shorter implant depth (13.6±0.9 mm vs 14.3±1.2 mm, p=0.004; OR:0.565, p=0.005). Conclusions UCDR on average increased segmental ROM with more than forty-percent of these implants being hypermobile at follow-up. Furthermore, shorter implant depth (AP) was indicated to be a risk factor for hypermobility. Patients and surgeons should be aware of the prevalence of hypermobility of UCDR and consider the long-term outcomes of the procedure. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

BACKGROUND CONTEXT Patient Reported Outcome Information System (PROMIS) provides a tailored ability to compare different procedures. This study compares PROMIS results for patients undergoing common single-level spinal surgery, total hip arthroplasty (THA) and total knee arthroplasty (TKA) procedures with minimum 1 Year Follow-Up (FU). PURPOSE To evaluate the efficacy of spine surgery compared to adult reconstructive surgery. STUDY DESIGN/SETTING Single-center retrospective cohort study PATIENT SAMPLE A total of 98 spine patients (32 Laminectomy, 22 MLD, 44 TLIF) and 147 RECON patients (50 THA and 97 TKA). OUTCOME MEASURES Patient demographics, Physical-Function (PF), Pain-Intensity (PI) and Pain-Interference (P-IF). METHODS Included: Patients>18 years old who underwent single level spine surgery (Lami, MLD, TLIF) or RECON surgery with Baseline (BL) & 1Y PROMIS scores of PF, P-IF, and PI, which were grouped based on surgery type. Excluded: patients who underwent both single level spine and RECON surgeries. Paired t-tests calculated differences in BL, 1Y, and change in PROMIS scores for spine vs each RECON procedure. RESULTS Age and gender were similar between spine (Age=58.92±13.69; 45.91% Female) and RECON (Age=65.9±8.6; 63.95% Female) patients. Spine patients undergoing Laminectomy(PF: 13.3±15.4, P-IF: 90.9±7.3, PI:56.2±6.6), MLD (PF:9.8±16.1,P-IF:94.2±6.4,PI:61.2±6.5) , or TLIF (PF:10.6±10.9,P-IF:91.8±13.0,PI:56.4±6.5) had more disability and pain at BL than either THA(PF: 36.0±4.7,P-IF:64.0±5.5,PI:54.2±6.2) or TKA(PF:35.5±3.9,P-IF:63.6±6.2,PI:53.3±6.6)patients according to all 3 PROMIS categories. When assessing all lumbar surgery patients with RECON, spine patients had greater improvements in PF (15.5±21 vs 6.8±6.3, p CONCLUSIONS Patients undergoing single level spinal surgery had worse baseline disability and pain compared to those undergoing recon surgery. PROMIS improvement is equivalent, and often greater in the spine patients compared to RECON. Although patients undergoing spine surgery had lower initial PROMIS scores than RECON patients, spine patients showed at least as good or better improvement at a 1Y postoperative time point. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

BACKGROUND CONTEXT Recombinant human bone morphogenetic protein 2 (rhBMP-2) is a popular biologic product used in transforaminal lumbar interbody fusion (TLIF) surgeries to promote fusion and avoid the morbidity associated with iliac crest autograft. However, use of rhBMP-2 and its effect on pseudarthrosis rates in TLIFs remains unknown. PURPOSE To assess the rates of pseudarthrosis in open and MIS TLIF patients, with and without concurrent rhBMP-2 use. STUDY DESIGN/SETTING Retrospective cohort study at a single academic institution. PATIENT SAMPLE Included: 317 single level TLIF patients. Consisting of 157 open TLIF (OTLIF), 115 bilateral Wiltse MIS TLIF (WTLIF), and 45 hybrid midline MIS with percutaneous pedicle or cortical screws (MTLIF). OUTCOME MEASURES Clinical characteristics, perioperative and postoperative outcomes, surgical procedure, rates of pseudarthrosis diagnosis, and revision for pseudarthrosis. METHODS Patients ≥18 years old undergoing 1-level TLIF with minimum 1-year of clinical and radiographic follow up were included. Pseudarthrosis was determined using both radiographic and clinical evaluations. Differences between groups were assessed by ANOVA and chi squared analyses. Demographic and perioperative characteristics were analyzed by multivariate logistic regression. RESULTS The cohort included 317 patients (mean age 59.68±13.29, F 52.7%). There was no significant difference in gender, BMI, or smoking status among groups (all p>.05). WTLIF had the lowest EBL (ml) (192.16±177.11mL vs 302.73±246.51 vs 363.85±370.49, respectively p= CONCLUSIONS MP use did not reduce the rate of pseudarthrosis or the number of reoperations for pseudarthrosis in this cohort. No difference in pseudarthrosis rates between the three TLIF approaches was noted. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

BACKGROUND CONTEXT C5 palsy stands as a known but poorly understood complication of cervical spine surgery with rates reported as high as 30%. Although there are multiple studies presenting different risk factors, variability in findings have led to controversy in the etiology of postoperative C5 palsy. PURPOSE To evaluate factors that predispose a patient to developing C5 palsy following cervical spine surgery. STUDY DESIGN/SETTING Retrospective review of a large single center academic institution. PATIENT SAMPLE This study included 239 cervical spinal procedures from 2013 to 2018. OUTCOME MEASURES Patient demographics, surgical procedure and approach, perioperative clinical characteristics, postoperative rate of C5 palsy, C5 palsy resolution, and radiographic outcomes. METHODS Patients ≥18 years of age who underwent cervical spinal surgery including the C4/C5 level, with minimum 1-year follow-up were included. C5 palsy was defined as deltoid +/- bicep weakness with Modified Rankin Scale grading at least 1 point below baseline (BL). Characteristics studied include: demographics, surgical procedure and approach (decompression and/or fusion). Radiographic analyses of MRI and CT measurements of foramen dimensions and spinal cord drift at BL and follow-up were performed. Statistical analyses included t-tests, chi-square analysis, and multivariate logistic regression to determine independent predictive factors. A receiver operating characteristic curve was run to determine the cutoff levels for predictive factors. Significance set at p RESULTS A total of 239 patients were included, with a C5 palsy rate of 6.3% for all cases. Subjects that developed C5 palsy were older (64.67±8.61 vs 57.56±11.61, p=0.021), had more levels decompressed posteriorly (3.20±1.82 vs 1.12±1.74, p CONCLUSIONS C5 palsy following cervical spine surgery is correlated with residual postoperative foraminal stenosis and posterior surgery with increasing number levels decompressed. Patients undergoing more than 3.5 level laminectomy with less than 2.625mm foramen width postoperatively are at highest risk of developing C5 palsy. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

BACKGROUND CONTEXT Expandable cages (EXP) are more frequently utilized in Transforaminal Lumbar Interbody Fusions (TLIF). Designed to reduce complications related to neurological retraction, enable better lordosis restoration, and improve ease of insertion, particularly in the advent of minimally invasive techniques they are exponentially more expensive than the non-expandable (NE) alternate. PURPOSE To investigate the value of expandable cages given the significantly higher cost. STUDY DESIGN/SETTING Retrospective review at a single institution. PATIENT SAMPLE A total of 257 TLIFs between 2012 and 2018 were included. OUTCOME MEASURES Clinical characteristics, perioperative and neurologic complication rates and radiographic measures. METHODS Patients ≥ 18 years of age who underwent single-level TLIF with minimum 1-year follow-up were included. Outcome measures: clinical characteristics, perioperative complications and neurologic complications. Radiographic analysis included change in pelvic incidence-lumbar lordosis (PI-LL), segmental lumbar lordosis (LL), and disc height restoration. Subsidence was radiographically assessed at 1-year follow-up from intraoperative imaging for breaching of the vertebral endplates, measured from the cage endplate to vertebral endplate and defined as a >2mm. Statistical analysis included independent t-tests and chi-square analysis with significance set at p RESULTS A total of 257 TLIFs between 2012 and 2018 were included, with 155 NE (53.5% female, mean age 59.46±14.07, mean BMI 28.69±5.39) and 102 EXP (49% female, mean age 57.78±11.76, mean BMI 28.72±6.01) with no significant differences in demographics. There were significantly more MIS TLIF cases and BMP use in the EXP group (88.2% MIS, p CONCLUSIONS Once technique was controlled for, TLIFs utilizing EXP do not have significantly different neurologic or radiographic outcomes compared to NE. These results question the value of EXP given the higher cost. The findings require further direct comparison in the MIS population because the benefit on outcomes compared to the alternate remains controversial due to the bias towards increased use in MIS procedures. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

BACKGROUND CONTEXT The thoracolumbar junction poses increased risk for high stress on upper lumbar discs when not adequately fused. However, controversy persists. This study evaluates outcomes of upper instrumented vertebrae (UIV) selection in the thoracic versus the upper lumbar spine when fusing to the sacrum. PURPOSE To compare revision rates for thoracolumbar fusions to the sacrum and pelvis at 1- and 2-year follow-up, stratified by UIV selection. STUDY DESIGN/SETTING Retrospective cohort study at a single institution. PATIENT SAMPLE A total of 968 patients who had thoracolumbar fusion surgery between 2012-2018 with at least one year of postoperative follow-up. OUTCOME MEASURES Reoperation rates from 1 and 2 years after revision surgery, reoperation diagnoses, body mass index (BMI), gender, Charleston Comorbidity Index (CCI), perioperative complications, ASA grade (ASA), operative time (OT), and blood loss (EBL). METHODS A retrospective review of patients undergoing revision spinal fusion with lower instrumented vertebra of S1 or pelvis between 2012-2018 at a single institution was performed. Patients with less than 1 year of follow-up after their index procedure were excluded from the analysis. Patients were categorized based on UIV into 6 groups: T9-T11, L1, L2, L3, L4, and L5. Demographic and operative data were collected and compared between the different UIV groups in each cohort using chi-squared and ANOVA tests. Revision rates at 1- and 2-year follow-up and the reasons for revision were compared between groups. RESULTS There were 168 revision spinal fusions that reached 1-year follow-up, with 54 having UIV at T9-T11, 2 fusions L1 to sacrum, 26 fusions L2 to sacrum, 25 fusions L3 to sacrum, 36 fusions L4 to sacrum, 23 fusions L5 to sacrum. There was significant difference in patient age, with oldest in the L1 group (65.5±3.5) and youngest in the L5 group (51±15.4 p CONCLUSIONS There is no statistically significant difference in reoperation rates for revision thoracolumbar fusions to the sacrum/pelvis associated with different UIV selection. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.