This study aims to compare three-dimensional (3D) and two-dimensional (2D) visualization in biportal endoscopic spine surgery using a simulated environment. Surgeons will perform standardized tasks on a spine model while using either 3D or 2D endoscopic systems. The goal is to determine whether 3D technology can improve precision, efficiency, and movement control during surgery. The study uses a randomized, blinded, crossover design to ensure objective results and may help guide future training and technology use in spinal endoscopy.

Spinal endoscopy, particularly the unilateral biportal endoscopic (UBE) technique, is an increasingly adopted minimally invasive approach for treating lumbar spine pathologies. While it offers clinical advantages over traditional open surgery-including less tissue disruption, reduced blood loss, and faster recovery-its uptake has been limited, in part due to the technical challenges associated with two-dimensional (2D) endoscopic visualization. The lack of depth perception inherent to 2D imaging can impair spatial orientation, hand-eye coordination, and surgical precision, especially in anatomically complex regions such as the lumbar spine.

Three-dimensional (3D) endoscopic systems are designed to address this limitation by restoring binocular depth cues and providing stereoscopic visualization. Preliminary evidence from other surgical fields-such as laparoscopy and cranial neurosurgery-suggests that 3D visualization improves operative performance, task efficiency, and user confidence. However, the benefits of 3D visualization in spinal endoscopy remain poorly understood, with no rigorous controlled studies to date assessing its impact on performance metrics under standardized conditions.

This randomized, blinded, crossover pilot study is designed to objectively evaluate the effect of 3D versus 2D endoscopic visualization on technical performance during simulated UBE procedures. Participants-including surgeons at various experience levels-will complete standardized surgical tasks on high-fidelity lumbar spine models using both 2D and 3D endoscopic systems. Motion tracking technology will be employed to quantitatively analyze instrument movement, capturing key metrics such as path length, velocity, motion economy, and high-velocity excursions.

The crossover design ensures that each participant serves as their own control, and blinding minimizes observational bias during performance assessment. The simulation setting allows for reproducible conditions free from patient-related variability, ensuring that observed differences can be attributed to visualization modality rather than anatomical or clinical complexity.

Findings from this study will provide foundational data on the potential utility of 3D visualization in spinal endoscopy, with implications for surgical training, operative safety, and the future integration of stereoscopic technologies in spine surgery.

Inclusion Criteria:

• Enrolled in the neurosurgical residency or fellowship program at the Department of Neurosurgery, Cantonal Hospital of St. Gallen, Switzerland
• Completion of basic neurosurgical training modules, including introductory endoscopic handling
• Age ≥ 18 years
• Willingness and ability to provide informed consent

Exclusion Criteria:

• Prior substantial experience with three-dimensional (3D) endoscopy (defined as > 5 independent procedures performed with 3D visualization systems)
• Ocular or neurological conditions impairing stereopsis, fine motor control, or safe endoscope handling
• Inability or unwillingness to complete the simulation protocol
• Declined participation

The study generated only simulation performance and questionnaire data from healthy volunteer trainees. No clinical or patient-level data were collected. Individual-level data will not be shared, but summary results are available in the publication.

In this single-center crossover simulation study, outcomes assessors responsible for performance evaluation and motion data analysis are blinded to the visualization modality used during each session (3D or 2D). Participants are not blinded due to the inherent perceptual differences between the two visualization systems. Investigators supervising the simulation are aware of the intervention assignments for operational purposes but are not involved in outcome assessment. All video and motion tracking data are anonymized and coded prior to analysis to maintain assessor blinding.