This randomized controlled trial compared decompression surgery plus fusion surgery (fusion group) to decompression surgery alone (decompression-alone group) for patients with lumbar spinal stenosis, with or without degenerative spondylolisthesis. 247 patients were randomly assigned to either the fusion group or decompression-alone group. The primary outcome was the Oswestry Disability Index score at 2 years, with no significant difference found between groups. Secondary outcomes and 5-year follow up results also showed no significant differences. The fusion group had longer hospitalization, more bleeding, and higher costs. During mean 6.5 year follow up, additional surgery rates were similar between groups. The study found that decompression surgery plus fusion did not result