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

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.

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.

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.

We introduce a validated mixed reality-integrated hand model simulator developed for training plastic surgery residents in metacarpal fracture reduction and fixation.