Effect of Baseline Adjacent Segment Degeneration on Clinical Outcomes After Lumbar Fusion

Study DesignCohort Study.ObjectivesEnd-stage degenerative segments above fusion levels have been associated with lower rates for surgical adjacent segment disease. We aimed to explore how this degeneration translates into patient reported outcomes.MethodsA consecutive series of lumbar fusion patients for degenerative pathologies were enrolled. Preoperative cranial adjacent segment degeneration status was determined using the Combined Imaging Score (CIS). Based on CIS, patients were trichotomized into mild (CIS <7), advanced (CIS 7-10), and end-stage (CIS >10) degeneration tertiles. In analysis, tertiles were adjusted for age, sex, and fusion length to control for potential confounders. The Oswestry Disability Index (ODI) was collected at baseline, 3 months, 1, 2, 5, and 10 years.Results197 patients were included. Postoperative improvements were similar across all CIS tertiles at all time-points, except for the marginal 10-point difference at 2-years, in favor of higher degeneration. Despite similar changes, end-stage degeneration (CIS >10) implied marginally lower disability levels at baseline and throughout follow-up.The 10-year all-cause mechanical reoperation rate was lowest in the third tertile (28%, 27%, 22%). Reoperation history was associated with greater disability among advanced degeneration (CIS 7-10); the ODI score difference 9 points, P = .009. Postoperative sagittal alignment was not reflected on physical performance.ConclusionsPreoperative adjacent segment degeneration status was only marginally reflected on 10-year disability outcomes. End-stage adjacent segment degeneration signaled lower reoperation risk and favorable functional outcomes. Our findings support the assumption that collapsed, end-stage degenerative segments without stenosis can be safely excluded from fusion constructs.