Comparative analysis of triplanar Chevron osteotomy (TCO) and Chevron osteotomy (CO) for treating mild to moderate hallux valgus via computer simulation and 3D printing: An observational study

Hallux valgus (HV) deformity, which is characterized by lateral deviation and pronation of the metatarsophalangeal joint, demonstrates complex 3-dimensional challenges, thus prompting the development of various surgical approaches, including traditional Chevron osteotomy (CO) and novel triplanar Chevron osteotomy (TCO). The objective of this study is to determine TCO at various tilt angles by employing 3D printing for ex vivo osteotomy angle simulations and computer modeling to correct deformities across 3 planes, thus aiming to enhance surgical outcomes by preserving or even increasing the length of the first metatarsal and thereby overcoming the limitations of CO. In this study, we collected and analyzed non-weight-bearing CT data from 55 patients (61 feet) with mild-to-moderate hallux valgus, plantar callosities and metatarsalgia from June 2019 to June 2020. The study utilized Mimics software for 3D digital reconstructions and simulation osteotomy of both TCO and CO. For both procedures, the apex was centered at the first metatarsal head, with CO specifically oriented towards the fourth metatarsal head at a 60° angle. The plantar-oblique Chevron osteotomy (POCO) was defined by a 15° plantar tilt, whereas TCO involved a further 9° tilt towards the metatarsal head. The key metrics that were measured included the hallux valgus angle (HVA), 1-2 intermetatarsal angle (IMA), distal metatarsal articular angle (DMAA) and first metatarsal length (FML). Our study aged between 30 and 71 years, with an average age of 47.37 years. Postoperative assessments using Mimics software showed significant improvements in reducing the HVA, IMA, and DMAA after CO and TCO. However, when comparing both techniques, their corrective capacities were roughly equivalent, with no significant differences observed in these metrics. Notably, compared with CO, TCO significantly increased the FML (P < .001), thus suggesting that TCO has greater potential to effectively prevent transfer metatarsalgia. This study underscores the ability of TCO to significantly extend the first metatarsal, with precise adjustments to its distal tilt to tailor deformity corrections. In computational simulation experiments, TCO offers a superior alternative to CO for treating hallux valgus by addressing 3-dimensional deformities and preserving or even increasing FML, thereby preventing transfer metatarsalgia.