Pathomechanics of congenital and acquired hallux varus: a clinical and anatomical study.

Hallux varus was observed in 69 feet among patients from a rural Indian population. This included three types of congenital hallux varus. The congenital "primary" type was the commonest and was not associated with any other foot deformity. Among the acquired forms was idiopathic hallux varus of middle age, which developed spontaneously in unshod persons and progressed gradually. Hallux varus following chronic arthritis was part of a consistent pattern of foot deformities in which the first ray collapsed in a zig-zag manner in two planes. Although the development of hallux varus is often due to intrinsic muscle imbalance, hallux varus secondary to chronic arthritis seems to occur as a result of both intrinsic and extrinsic muscle imbalance associated with midtarsal and subtalar arthritis. Muscular factors contribute to progression of the deformity also. No anatomical basis for a racial predilection for the deformity was noted. Failure to use footwear could account for the higher incidence of hallux varus in India.