Hallux valgus interphalangeus (HVI), unlike the more common deformity hallux valgus, has not received much attention in foot and ankle literature. Hallux valgus interphalangeus involves lateral deviation with internal rotation of the distal phalanx in relation to the proximal phalanx. The deformity usually presents early in life and can rapidly progress during growth spurts.
Possible etiologies of HVI include obliquity of the articular surface of the proximal phalangeal head and an asymmetrical shape of the distal phalanx. A deviation of the articular surfaces of the interphalangeal joint is present in the deformity. Lateralization of the extensor hallucis longus (EHL) tendon insertion has also been cited as an influencing factor. Operative treatment options include osteotomy of the proximal phalanx or interphalangeal joint fusion. While mild cases of the deformity can be corrected after skeletal maturity with the osteotomy, arthrodesis of the interphalangeal joint provides the greater amount of correction with more reliable long term results.
Hallux valgus interphalangeus is a complex deformity involving the articulation as well as the neighbouring soft tissue. The deformity can progress rather rapidly, so early surgical intervention is recommended. Be cause the deformity is usually rigid and severe, arthrodesis of the interphalangeal joint is recommended to provide reliable and long-lasting correction.