Relationship of foot deformity to ulcer location in patients with diabetes mellitus.

The purpose of this study was to determine whether a relationship existed between type of foot deformity and the location of ulcers in patients with diabetes and insensitive feet. Forty-two ulcerated feet were examined in 40 patients. All patients had severely decreased or absent sensation. Foot deformities were classified according to operational definitions as 1) Charcot's foot, 2) a compensated forefoot varus, or 3) an uncompensated forefoot varus or forefoot valgus. The plantar surface of the midfoot and forefoot was divided into three regions. Six of the 7 patients with a Charcot's foot showed ulceration at the midfoot. Nine of 18 patients with a compensated forefoot varus showed ulceration at the second, third, or fourth metatarsal head. Fifteen of 17 patients with an uncompensated forefoot varus or forefoot valgus showed ulceration at the first or fifth metatarsal. A significant relationship was found between foot deformity and location of ulcer. These results support the hypotheses 1) that insensitivity, coupled with increased, repetitive pressure, is a primary cause of plantar ulcers and 2) that certain foot types are associated with characteristic patterns of pressure distribution and callus formation.