Interdigital clavus: predisposition is the key factor of soft corns.

The soft corn is defined as an interdigital hyperkeratosis. Footwear contributes to interdigital corns when there is a congenital or acquired predisposing factor. These predisposing factors cause apposition of particular bony prominences between adjacent toes. The congenital factors include a short first metatarsal, a short fifth metatarsal, or third and fourth metatarsals of equal length. The acquired predisposing factors are hallux valgus and associated abduction, hammer deformity, burrowing and curling of the lesser toes. Sixty-five per cent of the 1,063 interdigital corns studied occurred in the fourth interspace. Seventy per cent of the fourth interspace corns occurred between the proximal interphalangeal joint of the fourth toe and distal interphalangeal joint of the fifth toe. Conservative treatment is recommended for most cases.