Impact of age and frailty on postoperative outcomes of single-level lumbar unilateral laminectomy bilateral decompression via biportal endoscopic spine surgery: retrospective, single institute study, Korea

Objective: This study investigated the impact of chronological age and frailty, assessed using the 11-item modified frailty index (mFI-11), on postoperative outcomes following single-level unilateral biportal endoscopic unilateral laminetomy with bilateral decompression (UBE-ULBD) in older patients with lumbar spinal stenosis.Methods: This retrospective study included 85 patients aged 60 years and older who underwent UBE-ULBD at a single institution between January 2015 and December 2020. Patients were stratified by age (60s, 70s, 80s) and mFI-11 score (0.00, 0.09, ≥0.18). Clinical outcomes included the visual analog scale (VAS) for pain, Oswestry disability index, the Macnab criteria, complication rates, and length of hospital stay (LOS). Statistical analyses involved analysis of variance, the chi-square test, and correlation analysis.Results: Chronological age showed significant correlations with postoperative VAS (r=0.312, P=0.004), LOS (r=0.265, P=0.015), and the Macnab criteria (r=–0.298, P=0.007). However, mFI-11 was not significantly associated with VAS, complication rates, or LOS. A comparison between mFI-11 subgroups (≤0.09 vs. ≥0.18) also showed no significant differences in clinical outcomes.Conclusion: Chronological age, rather than frailty measured by mFI-11, was significantly associated with postoperative pain, satisfaction, and LOS. Age may be a more practical predictor of outcomes in older patients undergoing UBE-ULBD and should be emphasized in preoperative assessments.