P132. Is there a difference in clinical outcomes between single level and two level anterior lumbar interbody fusion for degenerative disc disease

BACKGROUND CONTEXT Anterior lumbar interbody fusion (ALIF) has shown significant improvements in clinical outcomes for patients with degenerative disc disease causing lower back pain and foraminal stenosis. However, few studies have examined if there is a difference between outcomes in single level vs two level standalone ALIF. PURPOSE The purpose of this study was to assess for a difference in outcomes in single level vs two-level ALIF. STUDY DESIGN/SETTING Retrospective cohort study of patients treated at a single academic institution by a single surgeon. PATIENT SAMPLE Consecutive adult patients from 2011 to 2019 with the diagnosis of degenerative disc disease who underwent a single level (L5-S1) vs two level (L4-S1) standalone ALIF were included in this study. Only patients with 6 months of follow-up were analyzed. OUTCOME MEASURES Patient demographic data including age, body mass index, gender and American Society of Anesthesiologists classification was collected. Visual analog scale (VAS) pain scores for the back and leg, Oswestry Disability Index (ODI), Short Form 12 (SF-12) and Veterans RAND 12 (VR-12) scores were collected for clinical outcomes preoperatively and at the final postoperative visit. METHODS This study was a retrospective review of prospectively collected data. The patients were divided into cohorts of single level vs level ALIFs. Demographic data was compared between the two cohorts to look for baseline differences. Changes between preoperative and final clinical outcomes were compared using bivariate and multivariate linear regressions. Patients who achieved the minimal clinically important difference (MCID) in VAS and ODI scores from both groups were further analyzed with bivariate and multivariate linear regressions to assess for significant differences in outcomes. RESULTS A total of 73 patients were included. Fifty-six (76.7%) underwent a single level ALIF and 17 (23.3%) underwent two level ALIF. There were no baseline differences in patient demographics, nor in preoperative clinical scores. Both cohorts demonstrated improvements in all clinical outcomes postoperatively, and there was no significant difference between either group in bivariate and multivariate regression analysis of the postoperative clinical outcomes. Twenty patients (35.7%) in the single level ALIF cohort and seven patients (41.2%) in the two-level ALIF groups met the MCID cutoffs in VAS and ODI scores, and there was no significant difference between these patients in outcomes. CONCLUSIONS Both single-level L5-S1 and two-level L4-S1 standalone ALIF for degenerative disc disease demonstrate improvements in all clinical outcomes postoperatively. There is no significant difference between patients who underwent a single-level vs two-level stand-alone ALIF. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.