Simulation-Based Corrective Osteotomy with Predicted Postoperative Forearm Rotation for Distal Radioulnar Joint Instability.

Background: Distal radioulnar joint (DRUJ) instability associated with forearm bone deformity is difficult to treat because residual osseous malalignment may impair forearm rotation even after triangular fibrocartilage complex (TFCC) reconstruction. This study evaluated the clinical usefulness of preoperative three-dimensional (3D) computer simulation and patient-matched instruments (PMIs) for corrective osteotomy in deformity-related DRUJ instability. Methods: Three patients with chronic DRUJ instability associated with forearm bone deformity underwent corrective osteotomy based on 3D computer simulation and PMI-assisted surgery. Preoperative simulation was used to determine osteotomy planes, correction angles, and postoperative forearm rotation. Patient-matched surgical guides and plates were manufactured according to the simulation. Corrective osteotomy was combined with TFCC repair or reconstruction. Clinical outcomes were evaluated based on pain, range of motion, grip strength, redislocation and Modified Mayo Wrist Score (MMWS). Results: Bone union was achieved in all patients within 6 months. Postoperative radiographs demonstrated correction of osseous deformity and reduction of the DRUJ. Forearm rotational limitation improved in all cases with fixed dislocation, and dynamic instability resolved in the remaining case. Wrist pain disappeared in all patients, and grip strength and MMWS improved without major complications. Conclusions: Preoperative 3D computer simulation and PMI-assisted corrective osteotomy enabled accurate restoration of osseous alignment and forearm rotation in deformity-related DRUJ instability. Combining corrective osteotomy with TFCC repair or reconstruction may provide stable and functional outcomes. Level of Evidence: Level IV (Therapeutic).