In-house 3D-printed LLETZ simulator outperformed commercial model in RCT among traineesIn-house 3D-printed simulator improved surgical training scores compared to commercial models in this study

PURPOSE: Traditional surgical training methods such as "learning-by-doing" raise ethical and methodological concerns. To improve training and reduce patient risk, a 3D-printed LLETZ simulator was developed. While initial studies showed advantages over a conventional model, they were limited to medical students and lacked comparison with a commercially available simulator. METHODS: A single-center study was conducted at the University Hospital Wuerzburg. 60 medical students without prior LLETZ experience and 10 gynecology residents with prior exposure were randomly assigned to train on either a commercial or the novel in-house simulator. Each participant performed five electrosurgical excisions. Performance was evaluated using LEEP scores, resection status (R0 resections), and blinded video assessments by two senior clinicians. Additionally, participants completed questionnaires, to capture subjective training impressions. RESULTS: The in-house simulator demonstrated superior performance compared to the commercial model. When analyzed separately, changes in LEEP scores over the five attempts were statistically significant for both simulators. The effect size was larger for the in-house simulator (η = 0.227) than for the conventional simulator (η = 0.10). Within-group analysis revealed no significant pairwise differences across all attempts for the commercial simulator. In contrast, several pairwise comparisons remained statistically significant for the in-house simulator (attempts 1 vs. 3, 1 vs. 4, 2 vs. 5, and 1 vs. 5), all with large effect sizes (Cohen's d > 1.1). Between-group comparison of individual LEEP scores showed a statistically significant difference in the fifth attempt (p = 0.002), with a large effect size (Cohen's d = 1.01) favoring the in-house simulator. Higher R0 resection rates were observed with the in-house simulator in the third (100% vs. 83.3%) and fourth attempts (96.7% vs. 73.3%). Blinded video assessments by two senior experts confirmed these findings, demonstrating higher checklist, Global Rating Scale (GRS), and overall mean scores for the in-house simulator from the third attempt onward (all p < 0.05; all Cohen's d > 0.8). Participant feedback further supported these results, indicating improved confidence, technical skills, and perceived educational value. CONCLUSION: This study demonstrated that the novel in-house 3D-printed simulator significantly outperformed the commercial model in objective surgical performance, learning progression and user satisfaction.