Hallux valgus is a deformity at the base of the big toe or the metatarsophalangeal joint in which the great toe or hallux is deviated or points toward the lesser toes; in severe types of the deformity, the great toe goes over or under the second toe.
The musculotendinous attachments in the great toe bypass without any attachment to the head of the metatarsal itself to be inserted into base of the proximal and distal phalanges. When the great toe is in a normal alignment, the muscle forces exerted around it are balanced. Deformity is associated with muscle imbalance at the metatarsophalangeal joint. The muscle imbalance increases with the deformity; in long-standing hallux valgus deformity, a contracture in the overpowering lateral muscles and stretching of the medial capsule exists. As the deformity increases, the metatarsal head becomes prominent medially giving rise to the "bunion" deformity.
A number of operative procedures and osteotomies have been devised and or modified over the years. The great variety of procedures and osteotomies devised underlines the fact that all hallux valgus deformities are not similar and no single versatile osteotomy can treat them all. Therefore, exact procedure(s) selected for operative intervention is based on carefully clinical and radiological evaluation and planning.