Degeneration and Instability and the Relation to Patients' Function Late After Lumbar Disc Surgery Data from a 12-Year Follow-Up

Objective: To investigate the excess risk of degeneration and segmental instability in operated segments late after lumbar disc surgery in patients with presurgically stable segments, and whether local pathological findings relate to patients' back health. Design: This retrospective analysis reports on 69 patients 12 years after firsttime, uncomplicated lumbar disc surgery. Two independent radiologists evaluated the patients' lumbar functional x-rays; the Back Pain Rating Score (LBP-RS) assessed back-specific function. Results: At 12 years after lumbar disc surgery, degenerative changes as well as segmental instability occurred significantly more frequently in the operated than nonoperated lumbar segments, but there was no association between increased degeneration and segmental instability rates. The risk for acquiring segmental instability was significantly associated with surgery (odds ratio, 6.5; 95% confidence interval, 1.5-28.8). Prevalence of segmental instabilities was associated with better LBP-RS scores. Analyses of LBP-RS subscores revealed a clear association of segmental instability with physical function, but not with pain or activities of daily living. Conclusions: Lumbar disc surgery seems to be associated with an increased risk of degeneration and segmental instability in the long term. This structural impairment, however, seems functionally well compensated and does not seem to be a relevant causal factor for a chronic back pain syndrome.