Sonography of the sole of the foot. Evidence for loss of foot pad thickness in diabetes and its relationship to ulceration of the foot.

The hypothesis that loss of tissue mass in the foot contributes to foot ulceration in diabetics has never been quantitated. We developed normal criteria for the thickness of the sole of the foot at the heel, and the five metatarsal heads of both feet, using high-resolution ultrasound (10 MHz). We studied 24 normal patients ranging in weight from 125 to 250 lbs. We examined the soles of the feet of 38 diabetics without foot ulcers and 11 diabetics with foot ulcers or a history of foot ulcers who were in the same weight range as the normals. Of statistical significance, the heel thickness in controls was greater than that of the diabetics, which in turn was greater than that of the diabetics with foot ulcers. The thickness of the sole over the first and second metatarsals was also greater in the controls compared with diabetics. We conclude that high-resolution ultrasound is an effective determinant of the thickness of the sole of the foot and that diabetics have variations from the norm in the heel and at the first and second metatarsal heads.