Risk Factors for Reoperation in Patients Treated Surgically for Degenerative Spondylolisthesis

recurrent stenosis or progressive spondylolisthesis (45%), compliStudy Design. Retrospective analysis of prospective data from the degenerative spondylolisthesis (DS) arm of the Spine Patient Outcomes Research Trial. Objective. The aim of this study was to identify risk factors for reoperation in patients treated surgically for DS and compare outcomes between patients who underwent reoperation with nonreoperative patients. Summary of Background Data. Several studies have examined outcomes following surgery for DS, but few have identified risk factors for reoperation. Methods. Analysis included patients with neurogenic claudication (>12 weeks), clinical neurological signs, spinal stenosis, and DS on standing lateral x-rays. Univariate and multivariate analyses were used to investigate patient characteristics and risk factors. Treatment effects (TEs) were calculated and compared between study groups. Results. Of 406 patients, 72% underwent instrumented fusion, 21% noninstrumented fusion, and 7% decompression alone. At 8 years, the reoperation rate was 22%, of which 28% occurred within 1 year, 54% within 2 years, 70% within 4 years, and 86% within 6 years. The reasons for reoperation included