Single-Level Versus Two-Level Decompression for Adjacent Segment Spinal Stenosis : A Spinal Canal Area-Matched Comparative Study

Retrospective cohort study. To investigate clinical outcomes between lumbar decompression without fusion by matching canal area between the adjacent level in one-level decompression and the upper level in two-level decompression procedures. In patients with multilevel lumbar stenosis, surgeons face the dilemma of whether to decompress only the symptomatic level or to prophylactically include adjacent stenotic segments. Current literature shows little consensus on this decision, with comparative studies indicating that single-level and two-level decompressions yield similar pain relief, functional outcomes, and reoperation rates. Furthermore, no comparison has been made between decompression groups that accounts for the severity of stenosis at the upper adjacent level. Preoperative imaging was evaluated for dural sac cross-sectional area (DSCSA) and spinopelvic parameters. A 1:2 propensity score-matched analysis was performed using age, sex, comorbidity, and DSCSA to compare reoperation rates and patient-reported outcome measures (PROMs). A total of 349 patients were included in the matching process. In matched cohort, overall reoperation rates were similar between groups (21.2% vs. 21.2%). However, reoperation at the upper adjacent level showed a trend toward higher rates in the single-level group [16.7% vs. 3.0%; P =0.057; number needed to treat (NNT) = 8], although this did not reach statistical significance. Both groups exhibited similar improvements in PROMs and recovery patterns. Single-level and two-level decompression groups exhibited similar clinical outcomes in patients with symptomatic stenosis at one level and radiographic stenosis at the upper adjacent level. The two-level decompression group may be associated with a relatively lower reoperation rate at the upper adjacent level, suggesting possible benefit of two-level decompression.