Impacts of Prior Lumbar Laminectomy and Fusion on Long Segment Thoracolumbar Fusion for Adult Spinal Deformity.

Abstract

Retrospective Cohort Study. This study examined whether prior lumbar laminectomy or fusion at overlapping levels affects outcomes after long-segment thoracolumbar fusion for ASD. Adult spinal deformity (ASD) from age-related degeneration is increasing with an aging population. Long-segment thoracolumbar fusion is an option for adults with severe deformity or misalignment, but prior lumbar surgery may increase operative complexity and prolong recovery. We reviewed 219 adults undergoing ≥4-level thoracolumbar fusion for ASD (2016-2021), grouped by prior overlapping fusion (n=65), laminectomy alone (n=36), or no lumbar surgery (n=118). The primary outcome was time to revision, evaluated using Kaplan-Meier and adjusted Cox analyses. Secondary outcomes were complications and change in Oswestry Disability Index (ODI) among patients with paired scores and ≥6 months of follow-up. Patients with prior lumbar fusion more frequently presented with sagittal deformity or mechanical failure, lower median Cobb angle, and greater sagittal vertical axis than surgery-naïve patients. Revision-free survival differed significantly among groups (log-rank χ²=20.0, P<0.001). Prior lumbar fusion was independently associated with increased revision risk compared with no prior lumbar surgery (hazard ratio [HR], 2.93; 95% confidence interval [CI], 1.58-5.44; P<0.001), whereas prior laminectomy was not (HR, 0.55; 95% CI, 0.23-1.34; P=0.186). Among 174 patients with paired ODI scores, median ODI improvement was 14 points in surgery-naïve patients, 6 points after prior laminectomy, and 10 points after prior fusion (P=0.478). Minimum clinically important difference achievement did not differ among groups (52.2%, 40.7%, and 42.1%, respectively; P=0.376), nor did postoperative complication rates. Prior overlapping lumbar fusion, but not prior laminectomy, was independently associated with greater revision risk after long-segment thoracolumbar fusion for ASD. Prior fusion and laminectomy should be considered separately during preoperative counseling and operative planning.