Reoperations after surgery for lumbar spinal stenosis

Objective To study the indication for reoperations after lumbar decompression, the factors predisposing to redo operations, and the effect of prior instrumentation on developing adjacent level stenosis requiring reoperation. Methods Kaplan-Meier analysis was used to compare the median interval to first reoperation. Cox regression was used for multivariate analysis of time to first reoperation. Results Of 335 patients who underwent surgery for lumbar spinal stenosis, 63 (18%) underwent instrumentation in addition to decompression. There were 50 reoperations performed in 44 patients (13%). Of these 50 reoperations, 26 were at the same level, 14 were at the same level plus an adjacent level, and 10 were at an adjacent level. In 21 reoperations, the indication was adjacent level spinal stenosis; in 16, adjacent level spinal stenosis plus instability; in 9, instability alone; and in 4, disc problem. The risk of reoperation was higher among male patients (hazard ratio [HR] 1.2, 95% confidence interval [CI] 0.5862.635) and in patients with prior instrumentation (HR 1.7, 95% CI 0.6844.640). There was no statistical association between prior instrumentation and subsequent risk of reoperation (P = 0.12). There was no association between prior instrumentation and development of adjacent level stenosis requiring reoperation (P = 0.473). Conclusions Many patients with spinal stenosis undergo instrumentation because of instability. Most patients in this study underwent reoperation at the same level, and the most common pathology was spinal stenosis. The risk of reoperation was lower in older patients (<65 years old). Although there was a trend that the risk of reoperation was higher among patients with prior instrumentation, it did not reach statistical significance. In this study, there was no association between prior instrumentation and adjacent level stenosis requiring reoperation. These findings need to be evaluated further in randomized trials.