The Zone of Proximal Development in Laparoscopic Skill Acquisition – A Randomised Controlled Trial Into the Effect of Mentoring in Surgical Training

Simon J Cole, BScHons, Hugh Mackenzie, MBBS, BSc, MRCS, Joon Ha, MBBS, BScHons, George B Hanna, PhD, FRCS, Danilo Miskovic, MD, FRCS

Department of Surgery and Cancer, Imperial College, St. Marys Hospital, Praed Street, London, UK, W2 1NY

Introduction:
The Zone of Proximal Development (ZPD) is the potential gain conferred by mentored over independent training. This study aimed to investigate the ZPD in laparoscopic skill acquisition in novice surgeons using simulated laparoscopic cholecystectomy.

Methods and Procedures:
Seventeen surgically naive medical students performed 10 consecutive laparoscopic cholecystectomies on a virtual reality (VR) simulator. They were randomised into two groups; (i) eight into an intervention group who received structured, mentored training for procedures 1-9 (ii) nine into a control group (self-directed training). Procedure 10 was performed independently by both groups. Laparoscopic surgical and cholecystectomy knowledge was tested before the first, fifth and tenth operation using a structured written test. Simulator metrics were recorded for all operations. The surgical quality of procedures 1, 5 and 10 was assessed by two blinded, independent raters using the Competency Assessment Tool (CAT). Outcomes were compared using the Mann-Whitney U test. Proficiency gain curves were plotted using curve fit and CUSUM curves.

Results:
The baseline knowledge for both groups was similar (p=0.33); however the intervention group scored significantly higher on the subsequent knowledge tests (p=0.03). Both groups showed significant improvement for the simulator metrics across the 10 operations; the intervention group had a marginally greater improvement in the number of movements (7.3%) and path length (2.2%). The mean operating time was significantly shorter for the control group (13:28 minutes vs. 17:10 minutes, p<0.001). The intervention group performed significantly fewer errors (1.25 vs. 2.72 p=0.05) and reached competency after operation 6 whereas the control group was still on the learning curve after 9 procedures. The intervention group performed significantly higher quality surgery at each stage of the operation, as demonstrated by the CAT scores (p<0.001). This difference was retained for the independently performed 10th procedure (CAT score 2.97 vs. 2.19, p< 0.001).

Conclusions:
Structured mentored training is an important and effective training intervention and a ZPD could be observed in this study. Self-directed training may be applicable for the gain of manual skills, but not for the acquisition of complex procedural skills.

Session: Poster Presentation

Program Number: P167