Contribution Ratio of Metatarsal Osteotomy and First Tarsometatarsal Joint Reduction in Moderate to Severe Hallux Valgus Correction

Hallux valgus is a common foot and ankle disease, for which numerous surgical procedures were introduced. So, understanding the mechanism of deformity reduction is important to select the proper method. Intermetatarsal angle (IMA) determines the severity of hallux valgus, which is influenced by the translated metatarsal head and the reduction of the first tarsometatarsal joint. We hypothesized that both of the mechanisms simultaneously contribute to the correction of IMA. Hallux valgus (70 feet) operated with a Scarf osteotomy with the Akin procedure were reviewed. Hallux valgus angle (HVA), IMA (mechanical and anatomical), hallux valgus interphalangeal angle (HVIP), distal metatarsal articular angle (DMAA), and sesamoid position were checked. The ratio of contributions to the IMA changes were calculated and compared. When the individual contributions by metatarsal head translation and first tarsometatarsal joint reduction were compared, metatarsal head translation contributed by 82%, whereas first tarsometatarsal joint reduction contributed by 18%. Both were responsible for mechanical IMA correction. However, IMA change by metatarsal head translation was a major correction mechanism compared to anatomical IMA change by first tarsometatarsal joint reduction.