Study design: Randomized trial with a concurrent observational cohort study.
Objective: To compare 8-year outcomes between surgery and nonoperative care and among different fusion techniques for symptomatic lumbar degenerative spondylolisthesis (DS).
Summary of background data: Surgical treatment of DS has been shown to be more effective than nonoperative treatment out to 4 years. This study sought to further determine the long-term (8-year) outcomes.
Methods: Surgical candidates with DS from 13 centers with at least 12 weeks of symptoms and confirmatory imaging were offered enrollment in a randomized controlled trial (RCT) or observational cohort study (OBS). Treatment consisted of standard decompressive laminectomy (with or without fusion) versus standard nonoperative care. Primary outcome measures were the Short Form-36 (SF-36) bodily pain and physical function scores and the modified Oswestry Disability Index at 6 weeks, 3 months, 6 months, and yearly up to 8 years.
Results: Data were obtained for 69% of the randomized cohort and 57% of the observational cohort at the 8-year follow up. Intent-to-treat analyses of the randomized group were limited by high levels of nonadherence to the randomized treatment. As-treated analyses in the randomized and observational groups showed significantly greater improvement in the surgery group on all primary outcome measures at all time points through 8 years. Outcomes were similar among patients treated with uninstrumented posterolateral fusion, instrumented posterolateral fusion, and 360° fusion.
Conclusion: For patients with symptomatic DS, patients who received surgery had significantly greater improvements in pain and function compared with nonoperative treatment through 8 years of follow-up. Fusion technique did not affect outcomes.
Level of evidence: 1.