Single-Lens Reconstructed Three-Dimensional Versus Two-Dimensional Visualization in Uniportal Full-Endoscopic Unilateral Laminotomy with Bilateral Decompression for Lumbar Spinal Stenosis: A Retrospective Comparative Study

Background: Full-endoscopic unilateral laminotomy with bilateral decompression (ULBD) through a single portal lacks stereopsis, which dual-lens three-dimensional (3D) endoscopes cannot supply. This study evaluated whether a single-lens 3D reconstructed system shortens key operative steps, whether the benefit is greater with segmental deformity, and whether 12-month outcomes differ. Methods: Sixty-seven consecutive patients undergoing single-level uniportal full-endoscopic ULBD (2023–2024) were retrospectively reviewed; the same endoscope was used in two-dimensional (2D) mode (n = 33) or single-lens 3D mode (n = 34). Allocation was not randomized; assignment to the 2D or 3D group was determined by insurance coverage rather than by the investigators. Operative times were analyzed in all 67 patients; pain and function were analyzed in the 62 who completed 12-month follow-up. Deformity was present in 14 and 17 patients (p = 0.534). Times, pain, and function over 12 months were compared by two-way ANOVA with a system × deformity interaction. Results: 3D shortened time to drilling (4.4 vs. 6.1 min) and flavectomy (41.8 vs. 61.4 min; p < 0.001). The interval from initiation of drilling to completion of flavectomy—the deep portion of the procedure—was 17.9 min shorter with 3D (37.4 vs. 55.3 min; p < 0.001). The benefit depended on deformity (interaction p = 0.038): deformity prolonged that interval by 7.7 min with 2D but by 0.02 min with 3D. No complications or reoperations occurred. No statistically significant between-group difference in pain relief was detected, and the 12-month Oswestry Disability Index advantage with 3D (6.3 percentage points) fell below the minimum clinically important difference. Conclusions: Single-lens 3D reconstructed visualization shortens the deeper, working-channel portion of uniportal full-endoscopic ULBD and offsets the added time cost of deformed anatomy, but was not associated with a detectable improvement in clinical outcomes in this cohort.