Biomechanical Effects of Distal Fragment Translation Guided by Target Postoperative Intermetatarsal Angle in Minimally Invasive Transverse Osteotomy for Hallux Valgus: A Patient-Specific Finite Element Study

This study investigated the biomechanical effects of distal fragment translation guided by target postoperative first–second intermetatarsal angle (IMA) in minimally invasive transverse osteotomy (MITO) for hallux valgus using patient-specific finite element models. Three-dimensional models were reconstructed from computed tomography data of three female patients representing mild, moderate, and severe hallux valgus. The distal first-metatarsal fragment was translated laterally to achieve target postoperative IMA values of 9°, 8°, 7°, 6°, and 5°. Maximum von Mises stresses of the first through fifth metatarsals and Kirschner wires, together with mean osteotomy contact pressure and contact area, were evaluated under standardized static standing. As the target IMA decreased, the required translation increased, osteotomy contact area decreased, and mean contact pressure increased in all models. First-metatarsal stress increased most markedly in the severe model, reaching 25.74 MPa at 5°. In the mild and moderate models, further correction at the smaller IMA settings produced relatively limited additional changes in metatarsal stress while fixation stress and osteotomy-interface demands continued to increase. In contrast, the severe model showed continued increases in first-metatarsal and fixation stresses with further correction. These exploratory findings indicate that the mechanical effects of correction depend on both the target postoperative IMA and the distal fragment translation required to achieve it.