Background: One-third of patients with neurogenic claudication caused by lumbar spinal stenosis have low-grade degenerative spondylolisthesis. Decompression in these patients is considered a risk factor for instability, and it remains unclear whether instrumented fusion should be added. This study aims to assess the long-term clinical outcomes of decompressive surgery without instrumented fusion in patients with symptomatic spinal stenosis regardless of low-grade degenerative spondylolisthesis.

Methods: In this retrospective cohort study, patients with lumbar spinal stenosis with or without spondylolisthesis undergoing decompressive surgery were studied, 9 years postoperatively. Pain, functionality, and satisfaction questionnaires were sent to 250 patients with spondylolisthesis and 200 randomly selected patients with stenosis. Demographic characteristics, surgical technique, reoperation indication and incidence, and patient-reported outcome measures were assessed.

Results: At long-term follow-up, the mean Oswestry Disability Index was 23.6 ± 20.15 in the spondylolisthesis group and 23.4 ± 20.9 (P = 0.957) in the stenosis group. The EuroQol-5D was 0.74 ± 0.28 and 0.75 ± 0.24 (P = 0.793), respectively. The Zurich Claudication Questionnaire score was 48.2% ± 18.8 and 49.6% ± 18.5 (P = 0.646), respectively. After 9 years of follow-up, comparable satisfaction rates were reported (69% of patients with spondylolisthesis and 68% of patients with stenosis; P = 0.855). Reoperation rates were comparable in the spondylolisthesis and stenosis group (7% vs. 6%).

Conclusions: This cohort study showed comparable satisfaction and clinical outcomes after decompressive surgery for symptomatic spinal stenosis in patients with and without grade 1 degenerative spondylolisthesis. Decompressive surgery can, therefore, be considered an effective treatment for symptomatic lumbar spinal stenosis, even if it is accompanied by degenerative spondylolisthesis. Therefore, routinely adding instrumented spondylodesis is not deemed necessary.