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BACKGROUND CONTEXT Lumbar microdiscectomy is the most commonly performed surgery for treatment of radicular pain resulting from lumbar disc herniations. A growing body of evidence has demonstrated the clinical benefit compared to nonoperative interventions, including rapid recovery, symptom improvement and high patient satisfaction. Index level fusion following microdiscectomy, however, has not been well addressed in the literature. PURPOSE The purpose of this study was to identify risk factors for index level fusion following single level lumbar microdiscectomy. METHODS Retrospective review of patients undergoing primary single level lumbar microdiscectomy at a single institution with at least 6-month follow-up. Demographics, comorbidities, radiographic parameters and intraoperative variables were assessed. Patients undergoing index level fusion following discectomy were compared to those undergoing discectomy alone using independent t-test and chi square analysis for continuous and categorical variables, respectively. Multivariate analysis was also done using a logistic regression model. Significance was set as p RESULTS A total of 1,805 patients were identified for inclusion in analysis. This included 74 patients with eventual index level fusion and 1731 patients with discectomy alone. The fusion rate following primary lumbar discectomy was 4.1%, which occurred on average at 35.55 months (± 37.55 months). Patient-related risk factors include history of smoking, diabetes mellitus, and obesity (p CONCLUSIONS In a large cohort of patients undergoing lumbar discectomy for herniated nucleus pulposus, the risk of subsequent index level fusion was 4.1%. Potential risk factors for eventual fusion include patient related factors such as smoking, diabetes and obesity, radiographic evidence of spinal instability or coronal deformity, and surgical approach. While reherniation requiring revision discectomy may necessitate the eventual need for fusion, revision discectomy alone may not be an independent risk factor. This is a preliminary study, however, and prospective studies with a larger number of patients with long-term follow-up is necessary to investigate and validate these potential risk factors. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

BACKGROUND CONTEXT Posterolateral fusion (PLF) is a common procedure for spinal fusion, either stand-alone or in combination with interbody fusion. Achieving solid fusion in stand-alone PLF is challenging. OSTEOAMP® is a novel allograft bone graft substitute (BGS) manufactured using a proprietary process that retains high levels of endogenous growth factors, and offers a promise of an effective solution for BGS in PLF. PURPOSE To compare radiologic and patient outcomes following stand-alone PLF that used a novel BGS vs local autologous bone (LAB). STUDY DESIGN/SETTING A propensity score-adjusted nonconcurrent multicenter prospective cohort study. PATIENT SAMPLE Patients undergoing PLF with either the novel BGS or LAB. The OSTEOAMP group underwent a 1- or 2-level procedure and the LAB group underwent a 1-level procedure. OUTCOME MEASURES Fusion, Oswestry Disability Index (ODI), back and leg pain, SF36 PCS and MCS at 12 months. METHODS Clinical and patient outcomes for PLF using OSTEOAMP (N=38 patients) or LAB (control, N=104 patients) from two prospective studies were compared utilizing a propensity score approach to reduce selection bias in baseline characteristics. After application of propensity score region, 38 OSTEOAMP and 82 LAB patients were included in the analysis. The weighted analysis was performed using propensity scores as weights. Fusion was defined as uni- or bilateral bridging bone on CT scans and an absence of angular and translational motion ( RESULTS The fusion rate was 84% and 61% in the OSTEOAMP and LAB groups, respectively (P=0.028, RR = 1.4 (95% C.I. = 1.0 to 1.9)). At 12-month follow-up, both groups showed statistically significant improvements in all outcomes. There was no difference in ODI outcomes between the groups. The average ODI at 12 months was 20.3 and 18.8 in the BGS and LAB subjects, respectively. There was a marked and significant improvement in SF 36 PCS in both groups (15.4 and 13.1 in BGS and LAB groups, respectively, n.s.). SF 36 MCS improved in both groups (7.1 and 7.6 in BGS and LAB groups, respectively). Both groups experienced similar improvements in back pain and leg pain. Safety outcomes were similar between the groups. CONCLUSIONS OSTEOAMP is a viable replacement for LAB and achieves better radiologic fusion rates and similar patient outcomes in stand-alone PLF. FDA DEVICE/DRUG STATUS OSTEOAMP® is compliant to 21 CFR 1271 and is regulated as a 361 HCT/P.

BACKGROUND CONTEXT Herniations of lumbar intervertebral discs are one of the most common injuries sustained across the United States, and present challenges in management for the spine surgeon. Though patients often experience symptomatic relief following surgical decompression, reherniation is a common, yet unpredictable occurrence that may lead to further adverse outcomes. PURPOSE The purpose of this study was to create a prognostic tool to identify patients at greatest risk for reherniation after surgery. STUDY DESIGN/SETTING Retrospective cohort study. PATIENT SAMPLE Patients were identified by reviewing magnetic resonance imaging (MRI) studies and clinical documentation to identify all patients receiving surgical decompression of the lumbar spine for a herniated nucleus pulposus (HNP) from 2006 to 2018. OUTCOME MEASURES Reherniation of a lumbar intervertebral disc after decompression surgery. METHODS Following identification of the eligible cohort, patient charts were subsequently queried for type, location and incidence of reherniation events after decompression surgery. Baseline demographic (age, sex, body mass index (BMI), American Society of Anesthesiologist (ASA) Class, smoking history), clinical (duration of symptoms, type of herniation, number of planned operative levels), and radiographic information (pelvic tilt (PT), pelvic incidence (PI), sacral slope (SS), coronal angulation (CA), lumbar lordosis (LL)) was also collected. Following an 80:20 training and testing data split, multiple imputation and LASSO logistic regression were employed to build and validate a predictive model to identify patients at risk for reherniations after surgery. Ten folds of cross-validation were used to identify tuning parameters for the LASSO logistic regression model, allowing for selection of the strongest predictors for reherniation events. This model was subsequently refit to the multiply-imputed data to allow calculation of pooled model estimates. A threshold to distinguish patients as low- or high-risk for reherniations was established using Youden's index. The threshold for statistical significance was set p RESULTS A total of 517 patients (318 male, 199 female) presented for surgical decompression of a lumbar HNP, in which 51 experienced reherniations after surgery. Patients had a mean age of 45.2±13.9 years, BMI of 29.4±6.3 kg/m2, and 22.4±28.0 months of follow-up. Most herniations were paracentral (431/517; 83.4%), followed by central (55/517; 10.6%), and far lateral (29/517; 5.6%). Reherniations were seen at a mean of 46.0±70.0 months after surgery. LASSO logistic regression identified nine significant predictors for reherniations: age, sex, ASA class, operative levels, duration of preoperative symptoms, paracentral disc herniation, preoperative PI, preoperative LL, and VAS-Leg scores. Paracentral disc herniations and duration of preoperative symptoms were the strongest positive and negative predictors for reherniation outcomes, respectively. Validation of this model demonstrated excellent model discrimination (AUC: 0.834), sensitivity (71.4%), and specificity (87.6%). Within the testing cohort, 16.3% and 83.7% of patients were identified as high- and low-risk, respectively. Of these, 29.4% of high-risk patients (5/17) sustained future reherniations, while nearly all low-risk patients (85/87; 98.7%) experienced no recurrence of their HNP. CONCLUSIONS This is the first study to develop and validate a screening tool to identify patients with clear differences in risk for reherniation after lumbar decompression for HNP. With further validation, this tool can be readily implemented in clinical practice, and may accurately identify patients likely to experience lasting surgical benefit for lumbar disc herniations. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

BACKGROUND CONTEXT Tranexamic acid (TXA) has been increasingly used to decrease blood loss during a large variety of surgical procedures, including joint arthroplasty and spinal deformity procedures. However, TXA is not routinely used in degenerative lumbar spine cases, and the optimal dosing regimen for these cases is not known. PURPOSE The purpose of this study was to explore the clinical utility of TXA in open posterior lumbar fusions (PLF) while comparing intravenous and oral dosing regimens. STUDY DESIGN/SETTING Prospective randomized controlled trial. PATIENT SAMPLE Patients indicated for open posterior lumbar fusion for degenerative pathology by one of three fellowship-trained spine surgeons were recruited for the study. Patients with procedures that included 4 or more levels, or those who had a current/recent history of thromboembolic events, allergy to TXA, and/or pregnancy were excluded. OUTCOME MEASURES Outcome measures assessed were postoperative reduction in hemoglobin and hematocrit, blood transfusion rate, calculated blood loss, and complications. METHODS Patients were randomized to one of four study arms: 1) oral placebo, 2) intravenous TXA at time of incision, 3) 1950mg oral TXA 1 hour before incision, and 4) 1950mg oral TXA 1 hour before incision, and 1950mg oral TXA once per day for three days after surgery. Differences between study arms were assessed using a combination of chi-square & ANOVA for categorical and continuous data, respectively. The threshold for statistical significance was set at p RESULTS A total of 79 patients (44/79; 55.7% female) were enrolled, with a mean age of 64.9±12.2 years, body mass index of 32.3±6.2 kg/m2, and an average of 1.9±1.4 vertebral levels fused. For each treatment group, 21, 19, 20, and 19 patients were assigned to study arms 1-4, respectively. There were no differences in baseline demographic or operative characteristics. Patients across the entire cohort had a mean postoperative reduction in hemoglobin and hematocrit of -3.2±1.4 g/dL and -9.8±4.2 %, respectively, with an associated 1999.2±841.9 ml of calculated blood lost. Four patients experienced postoperative anemia (Group 1: 2/19, 10.5%; Group 4: 2/17, 11.8%) requiring a blood transfusion of 2 units each. No patients experienced other serious hospital complications such as postoperative epidural hematoma formation, pulmonary embolism, deep vein thrombosis, or stroke. There were no significant differences between groups in postoperative reduction in hemoglobin and hematocrit, blood transfusion rate, calculated blood loss, or complications. Similarly, there were no differences in assessed outcomes between patients who received any form of TXA when compared to placebo. CONCLUSIONS TXA can be used safely in PLF, though there was no clear benefit in hemostasis when compared to placebo, and outcomes did not vary based on dosing regimen. These preliminary findings suggest that TXA may not have a clinically meaningful application in short-length open PLF. FDA DEVICE/DRUG STATUS TXA: Investigational.