Evaluation of a 3D Simulation Model for Unilateral Biportal Endoscopic Lumbar Discectomy: A Validity Study in Residency Training

Abstract

square OBJECTIVES: Unilateral biportal endoscopic (UBE) surgery is a minimally invasive technique increasingly used for lumbar spine pathologies. However, its learning curve is steep, and structured training is required before clinical practice. The aim of this study was to evaluate the educational validity and reliability of a three-dimensional simulation model for UBE lumbar discectomy according to Messick's validity framework. square METHODS: This single-center study was performed at Ankara Etlik City Hospital, Department of Neurosurgery in October 2025. Ten neurosurgeons participated: 6 residents (novices) and 4 experienced UBE surgeons (experts). Each participant performed a simulated lumbar discectomy task using the UpSurgeOn Endoscopic LumbarBox. Technical performance was assessed by a Task-Specific Checklist (TSCL) and a Global Rating Scale (GRS). Face, content, construct, internal structure, and consequence validity were analyzed statistically. square RESULTS: Experts achieved significantly higher TSCL (median 18.5 vs. 11) and GRS (30 vs. 17) scores, shorter task time (15 vs. 25 min), and fewer errors (1 vs. 3) compared with novices (P < 0.05). Inter-rater reliability was excellent (intraclass correlation coefficient = 0.93 for TSCL, 0.87 for GRS), and internal consistency was high (Cronbach's a >= 0.8). Face and content validity scores were strong (median >= 8/10). Novices showed a significant improvement in self-efficacy after training (26-56.5, P = 0.028) and a clear positive learning curve across 3 trials. square CONCLUSIONS: The three-dimensional simulation model demonstrated strong validity and reliability for UBE discectomy training. It successfully differentiated between experience levels and improved participants' confidence and technical skills. This simulator provides a safe and effective platform for developing UBE competencies during residency prior to real surgical application.