Two Surgeons, One Spine: Early Data on Simultaneous Dual-Surgeon Endoscopic Two-Level Lumbar Fusion

The retrospective single-center study, published in BMC Musculoskeletal Disorders, followed 39 patients who underwent simultaneous dual-surgeon unilateral biportal endoscopic transforaminal lumbar interbody fusion, or SDS UBE-TLIF, for two-level lumbar degenerative disease.

The study screened 206 patients and included 202. Of these, 163 underwent single-level procedures performed by Surgeon A (80 cases) or Surgeon B (83 cases), while 39 underwent the simultaneous dual-surgeon two-level procedure carried out by the same pair. The authors were careful to frame the single-level operations as experience context rather than a true control group for the two-level technique.

To characterize how operative times evolved, the researchers used mean-centered cumulative sum analysis and fourth-degree descriptive curve fits. Before the dual-surgeon program began, Surgeon A had completed 21 single-level procedures and Surgeon B 33, both beyond their fitted learning-curve divisions after cases 20 and 28. For the two-level SDS procedures, the fitted division fell near case 20: mean operative time was 305.5 plus or minus 44.3 minutes for cases 1 through 20, dropping to 241.3 plus or minus 43.9 minutes for cases 21 through 39.

A key check came from the surgeons’ contemporaneous single-level work. Among 109 single-level procedures performed during the same calendar period, regression analysis found no detectable downward linear trend in operative time for either surgeon.

Safety outcomes were tracked through postoperative day 30, with complications verified against records. Three of the 39 SDS patients experienced a complication within 30 days, a rate of 7.7 percent, with an exact 95 percent confidence interval of 1.6 to 20.9 percent. Risk-adjusted analyses were explicitly exploratory, and the small sample size means the true complication rate remains uncertain.

Clinical results were available for all 39 patients, with complete scores at every assessment point. Median final follow-up was 11.79 months, ranging from 3.09 to 16.59 months. Pain scores decreased over follow-up, and the mean Oswestry Disability Index, a standard measure of back-related disability, improved from 70.3 percent at baseline to 21.2 percent at the final visit.

Radiographic healing was assessed with computed tomography at approximately six months in 36 evaluable patients. Of 72 fused levels, 57, or 79.2 percent, met the Bridwell grade-I or grade-II criterion for fusion, and both levels met the criterion in 26 of 36 patients, or 72.2 percent. Cage subsidence occurred at 7 of 72 levels, 9.7 percent, and posterior cage migration at 2 of 72 levels, 2.8 percent.

The authors stress the limits of what this series can show. As a fixed-pair retrospective study, it documents the time-related demands and early outcomes of the technique but does not establish a proficiency threshold or demonstrate any comparative advantage over standard approaches. They call for prospective comparative assessment and longer follow-up before drawing conclusions about safety and durability.

Even so, the operative-time trajectories may offer practical value for teams considering the approach, informing initial scheduling, workflow review, and the design of future training evaluations. For now, the study stands as an early feasibility report on a two-surgeon, two-level endoscopic fusion model, with encouraging short-term pain and disability improvements that await confirmation in larger, controlled studies.

Subject of Research: Simultaneous dual-surgeon unilateral biportal endoscopic two-level lumbar interbody fusion for lumbar degenerative disease

Article Title: 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

Article References: Zhang, J., Wang, Z., Mou, L., Li, H., Wang, H., Zhu, W., Luo, H., Yang, H., & Lun, D. (2026). 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. BMC Musculoskeletal Disorders. https://doi.org/10.1186/s12891-026-10668-5

Image Credits: AI Generated

DOI: 10.1186/s12891-026-10668-5

Keywords: lumbar fusion, UBE-TLIF, endoscopic spine surgery, dual-surgeon surgery, operative time, learning curve, lumbar degenerative disease, Oswestry Disability Index, Bridwell fusion grade, retrospective study, spine surgery, minimally invasive