Risk for adjacent segment and same segment reoperation after surgery for lumbar stenosis: a subgroup analysis of the Spine Patient Outcomes Research Trial (SPORT).

STUDY DESIGN: Subgroup analysis of a prospective, randomized database.

SUMMARY OF BACKGROUND DATA: Reoperation due to recurrence of index level pathology or adjacent segment disease is a common clinical problem. Despite multiple studies on the incidence of reoperation, there have been few comparative studies establishing risk factors for reoperation after spinal stenosis surgery. The hypothesis of this subgroup analysis was that lumbar fusion or particular patient characteristics, such as obesity, would render patients with lumbar stenosis more susceptible to reoperation at the index or adjacent levels.

METHODS: The study population combined the randomized and observational cohorts enrolled in Spine Patient Outcomes Research Trial for treatment of spinal stenosis. The surgically treated patients were stratified according to those who had reoperation (n = 54) or no reoperation (n = 359). Outcome measures were assessed at baseline, 1 year, 2 years, 3 years, and 4 years. The difference in improvement between those who had reoperation and those who did not was determined at each follow-up period.

RESULTS: Of the 413 patients who underwent surgical treatment of spinal stenosis, 54 (13%) underwent a reoperation within 4 years. At baseline, there were no significant differences in demographic characteristics or clinical outcome scores between reoperation and nonreoperation groups. Furthermore, between groups there were no differences in the severity of symptoms, obesity, physical examination signs, levels of stenosis, location of stenosis, stenosis severity, levels of fusion, levels of laminectomy, levels decompressed, operation time, and intraoperative or postoperative complications. There was an increased percentage of patients with duration of symptoms greater than 12 months in the reoperation group (56% reoperation vs. 36% no reoperation, P < 0.008). At final follow-up, there was significantly less improvement in the outcome of the reoperation group in MOS 36-item Short-Form Health Survey physical function (14.4 vs. 22.6, P < 0.05), Oswestry Disability Index (-12.4 vs. -21.1, P < 0.01), and Sciatica Bothersomeness Index (-5 vs. -8.1, P < 0.006).

CONCLUSION: Lumbar fusion and instrumentation were not associated with increased rate of reoperation at index or adjacent levels compared with nonfusion techniques. The only specific risk factor for reoperation after treatment of spinal stenosis was duration of pretreatment symptoms more than 12 months. The overall incidence of reoperations for spinal stenosis surgery was 13%, and reoperations were equally distributed between index and adjacent lumbar levels. Reoperation may be related to the natural history of spinal degenerative disease.