A concept and prototype implementation of a surgical knot tying trainer. Implemented in Unity3D with Varjo XR-3 hardware and featuring instructions in the form of volumetric videos.

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Abstract

This study presents a mixed reality training concept designed to enhance medical students’ acquisition of surgical knot-tying skills, a fundamental component of surgical training critical for effective wound closure and tissue healing. Utilizing a virtual reality headset with video passthrough functionality, the system provides adaptive visual instructions tailored to the user’s hand movements during the knot-tying process. A prototype was developed based on the concept, featuring three-dimensional videos in which virtual instructor hands demonstrate each step of the procedure. The training concept was derived from an iterative, user-centered process encompassing requirement analysis, prototype development, and evaluation. Key functionalities include the ability to display thread tension and tensile strength, dynamically adapt learning speed to the user’s progress, and deliver personalized feedback by visually augmenting the hands and fingers. Evaluation results indicate that spatial and tangible interactions facilitated by the mixed reality training prototype support the acquisition of practical skills, bridging the gap between digital and physical simulation training.