P140. Risk factors for index level fusion following lumbar microdiscectomy

Abstract

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.