Early feasibility, operative-time trajectories, and safety observations of simultaneous dual-surgeon unilateral biportal endoscopic transforaminal lumbar interbody fusion for two-level lumbar degenerative disease: a retrospective study

Background Simultaneous dual-surgeon (SDS) unilateral biportal endoscopic transforaminal lumbar interbody fusion (UBE-TLIF) enables parallel work at two levels. This study characterized its implementation, operative-time trajectories, and early outcomes. Methods This retrospective single-center study included 202 of 206 screened patients: 163 single-level procedures (Surgeon A, 80; Surgeon B, 83) and 39 SDS procedures performed by the same pair. Single-level procedures provided experience context, not a two-level control. Operative-time trajectories were assessed using mean-centered cumulative sum (CUSUM) and fourth-degree descriptive fits. Surgeon-specific calendar-time regressions examined contemporaneous single-level procedures. Complications were verified through postoperative day 30; risk-adjusted analyses were exploratory. Pain and disability were assessed at baseline, 3 months, and final follow-up, with computed tomography (CT) at approximately 6 months. Results Before SDS initiation, Surgeons A and B had completed 21 and 33 single-level procedures, beyond their fitted divisions after cases 20 and 28. The SDS fitted division occurred near case 20; mean operative times were 305.5 ± 44.3 min for cases 1–20 and 241.3 ± 43.9 min for cases 21–39. Among 109 contemporaneous single-level procedures, neither surgeon showed a detectable downward linear time trend. Three SDS patients experienced a 30-day complication (7.7%; exact 95% confidence interval, 1.6–20.9%). All 39 had complete clinical scores; median final follow-up was 11.79 months (range, 3.09–16.59). Pain scores decreased, and mean Oswestry Disability Index improved from 70.3% to 21.2%. CT was evaluable in 36 patients: 57/72 levels (79.2%) met the Bridwell grade-I/II criterion, with both levels meeting it in 26/36 patients (72.2%). Subsidence occurred at 7/72 levels (9.7%) and posterior migration at 2/72 levels (2.8%). Conclusions This fixed-pair series documents the time-related demands and early outcomes of SDS two-level UBE-TLIF. The trajectories may inform initial scheduling, workflow review, and prospective training evaluation, but do not establish a proficiency threshold or comparative advantage. Safety and durability require prospective comparative assessment and longer follow-up.