A Novel Mixed-reality Simulator for Training Metacarpal Fracture Reduction and Kirschner Wire Fixation.

Background: Metacarpal fracture reduction and Kirschner wire (K-wire) fixation are core competencies in hand surgery that are difficult to master. Surgical simulation using extended reality technologies has improved intraoperative performance among trainees in various surgical subspecialties. Methods: Imaging data from an uninjured patient were used as a reference to construct a 3D-printed hand. Wire channels and electromagnetic sensors were added to aid real-time tracking. Fracture bridges allowed introduction of fractures after single-piece printing, and the hand model was cast in silicone to reproduce surface anatomy. A scanned model of a K-wire driver was 3D-printed with movable parts, and an application was designed to track the positioning of the hand model, fracture sites, and the driver. Ten plastic surgeons and 8 residents evaluated the hand model simulator based on realism, representational accuracy, and training utility using a 5-point Likert scale for validation. Results: Printing accuracy showed a 3D printing error in Hausdorff distance below 0.13 mm. The target registration error for the fractures was below 1 mm. Qualitative evaluations of anatomical accuracy, clinical comparability, reduction realism of fractures, and the perceived value of simulator training each achieved a median score of 5. Percutaneous entry point selection, K-wire placement, fluoroscopy replicability, and training realism received a median score of 4. Overall, all plastic surgeons and residents unanimously recommended the simulator as an effective training tool. Conclusions: We introduce a validated mixed reality-integrated hand model simulator developed for training plastic surgery residents in metacarpal fracture reduction and fixation.