Examining the Role of Pre-Operative Retrolisthesis in Single-Level Lumbar Fusion: Impact on Reoperation Rates

Background/Objectives: Lumbar fusion for degenerative pathology is increasingly common, yet revision surgery, often due to adjacent segment disease, remains a major concern. While sagittal alignment has been widely studied, the role of preoperative lumbar retrolisthesis is less clear. This study evaluated the prevalence, distribution, and clinical significance of preoperative retrolisthesis in patients undergoing single-level L4-L5 fusion, with a focus on its association with revision surgery. Materials and Methods: A retrospective cohort study of 116 adult patients undergoing single-level L4-L5 posterior fusion with multilevel decompression from 2018 to 2022 was performed. Retrolisthesis was defined as posterior translation ≥ 2 mm and assessed across lumbar levels. Patients were stratified by revision status. Statistical comparisons and Cox proportional hazards models were used to evaluate associations between retrolisthesis burden, radiographic parameters, and revision risk. Results: Preoperative retrolisthesis was present in 78.4% of patients, most commonly at L3-L4 and L2-L3, and frequently involved multiple levels. Presence of retrolisthesis alone was not associated with revision (85.7% vs. 77.5%, p = 0.73). However, patients with ≥3 retrolisthesis levels demonstrated reduced revision-free survival, with a higher hazard of revision on univariate analysis (HR 3.65, p = 0.055). In multivariate analysis, ≥3 levels (HR 5.50, p = 0.018) and greater absolute L4-S1 lordosis change (HR 1.09 per degree, p = 0.031) were independent predictors of revision. Conclusions: Retrolisthesis is highly prevalent in patients undergoing L4-L5 fusion but is not predictive of revision when considered alone. A greater multilevel retrolisthesis burden, particularly when combined with larger segmental lordosis change, may represent a mechanically vulnerable spine phenotype associated with increased revision risk. These findings should be interpreted as exploratory and require validation in larger cohorts.