Medical Student Carle Illinois College of Medicine, Minnesota, United States
Introduction: Many surgeons prefer to use posterior instrumentation to augment anterior lumbar interbody fusion (ALIF). In this study, we sought to study the adjusted benefit conferred by posterior instrumentation on surgical and patient-reported outcomes (PROs) on ALIF patients.
Methods: Using the Lumbar Quality Outcomes Database, we identified all patients undergoing ALIF, segmenting patients into anterior only and anterior with posterior instrumentation cohorts. The primary outcomes of our study were 30-day surgical complications, a 50% reduction in Oswestry Disability Index (ODI), and a reduction in back and leg pain via the visual analog scale (VAS). Multivariate analysis leveraged Firth’s logistic regression and propensity-score adjustment, constructed from demographics, baseline comorbidities, and indications for surgery.
Results: 1236 and 1214 patients were identified to receive ALIF with and without posterior instrumentation, respectively. Prior to adjustment, patients with posterior instrumentation had 24% greater rates of Grade 1 spondylolisthesis (p < 0.001), and greater rates of lumbar stenosis (15.3%, p < 001). Patients that had neurogenic claudication underwent posterior instrumentation at a 16.5% greater rate (p < 0.001). There were no statistical differences in post-operative surgical outcomes at 30-days between the two cohorts after propensity adjustment. Patients with posterior instrumentation had improved ODI at 3 months (OR = 0.671, p = 0.005), reduction of leg pain (OR = 0.697, p = 0.016), and reduction of back pain at 3- and 12-month periods (OR = 0.738, p = 0.033, OR = 0.630, p = 0.017, respectively). Outcomes at 24 months were equivalent between both cohorts.
Conclusion : We show in our analysis that patients undergoing posterior instrumentation for ALIF offers a short-term benefit to patients, adjusted for preoperative morbidity and baseline characteristics. In future analyses, the cost of posterior fixation should be weighed against the short-term improvement in PROs for a more effective cost-benefit analysis.
