No long term benefit of decompression of a borderline lumbar spinal stenosis level adjacent to a more stenotic index level.

Purpose: Lumbar spinal stenosis (LSS) frequently involves multiple levels of the spine. Whether to perform single-level decompression (SLD) or multi-level decompression (MLD) in patients with at least one borderline stenotic level adjacent to the primary (index) level, remains debated. Short-term follow-up studies show comparable outcomes for both strategies. This study aimed to assess five-year outcomes in patients with adjacent borderline stenosis.

Material: All participants were recruited from the NORDSTEN-SST. Patients with a preoperative adjacent borderline stenosis, defined as Schizas grade B or C, in addition to the index level, were included in the study. The cohort was divided into two groups based on the type of surgical intervention: SLD or MLD. Baseline characteristics and clinical outcomes were recorded for both groups, with follow-up conducted five years postoperatively. Subgroup analysis based on the Schizas grade in the adjacent level were also performed.

Results: Out of 437 patients in the NORDSTEN-SST, the 222 with borderline adjacent stenosis were included. Among these, 114 underwent SLD, while 108 underwent MLD. Baseline characteristics were comparable between groups. Mean change in ODI-score was - 16.0 (95% CI -18.9-12.9) for the SLD group and - 18.6 (95% CI -22.1-15.1) for the MLD group, p = 0.26. Subgroup analyses revealed no significant differences between groups in clinical outcomes or need for subsequent spinal surgeries.

Conclusion: In this observational study, five-year clinical outcomes in patients operated for lumbar spinal stenosis with a significant stenotic index level were not influenced by additional decompression of preoperative adjacent borderline stenotic levels.