Incidence and predictors of early and late reoperation after primary lumbar spine fusion: a 10-year retrospective cohort study of 1,356 patients.

Abstract

Unplanned reoperation remains a major concern following lumbar spinal fusion, yet limited evidence exists on the distinct predictors of early and late revision surgery using long-term competing-risk analyses. This study aimed to evaluate the incidence, timing, etiologies, and independent predictors of reoperation after primary instrumented lumbar fusion over a 10-year follow-up period. In this retrospective cohort study, 1,356 adult patients undergoing primary instrumented lumbar fusion between 2014 and 2024 were analyzed. Reoperations were categorized as early (≤ 90 days) or late (> 90 days). Cumulative incidence was estimated using Fine-Gray competing-risk models, accounting for mortality. Multivariable subdistribution hazard regression was used to identify independent predictors of reoperation. During follow-up, 133 patients (9.8%) underwent reoperation. Early revisions were mainly due to infection and acute complications, whereas late revisions were predominantly related to adjacent segment degeneration and pseudoarthrosis. Multilevel fusion, diabetes mellitus, obesity, osteoporosis, and prolonged operative time were independently associated with increased reoperation risk. A significant synergistic interaction between diabetes and obesity was observed. Reoperation after lumbar fusion demonstrates distinct early and late patterns driven by different mechanisms. Metabolic comorbidities and surgical complexity are key determinants of revision risk, highlighting the importance of risk stratification and perioperative optimization.