5 - Hallux Varus

Abstract

The type of treatment for correction of hallux varus is determined by the flexibility of the metatarsophalangeal (MTP) and interphalangeal (IP) joints. Imbalance is always present between the flexor hallucis brevis (FHB) and the extensor hallucis brevis (EHB) muscles and between the abductor hallucis and adductor hallucis muscles. As with any muscle imbalance, the deformity will generally gradually increase, causing a spectrum of fixed and flexible deformities of the MTP and IP joints, with or without arthritis of either joint. Fortunately, the IP joint remains flexible in most hallux varus deformities. Over time, however, with increasing imbalance of the FHB and EHB muscles, a contracture of the IP joint develops. If this contracture is rigid or if arthritis of the IP joint is present, an arthrodesis of this joint is usually necessary. If an IP contracture is present but the joint is fairly flexible, then we try to manipulate the joint and determine if a tendon transfer without arthrodesis is possible. Release of this contracture is generally not successful because of the contracture of the FHL in addition to tightness of the plantar capsule. Once an arthrodesis of the IP joint is performed, the MTP joint deformity must be corrected either dynamically with a tendon transfer or statically through restoration of ligament stability with a tenodesis.