Relationship between onychocryptosis and foot type and treatment with toe spacer. A preliminary investigation.

The relationship between onychocryptosis and foot type was investigated in a series of 512 patients. Of these patients, 124 had signs or a history of onychocryptosis. Among the nine foot types identified by digital and metatarsal formulas, the Greek index minus and squared index minus types showed the strongest association with onychocryptosis, which was present in more than one-third of such feet. When anteroposterior radiographs of each type of foot were taken after binding the first and second toes together to simulate a tight shoe, the enlargement of bony structures of the second toe at the distal interphalangeal level in the Greek and squared index minus feet moved toward the distal enlargement of the distal phalanx of the first toe where the ingrowing occurs. Ten cases of stage I and four cases of stage II onychocryptosis were treated by placing a toe spacer between the first and second toes; all healed in about 3 weeks, suggesting that counterpressure of the second toe in tight shoes is a factor in the development of onychocryptosis.