Date of Award


Document Type


Degree Name

Doctor of Philosophy (PhD)



First Advisor

B. Don Franks


This dissertation reviews the pathomechanics of plantar ulceration in patients with diabetes mellitus, and studies the relationship between joint mobility, pressure and the location of ulceration at the first metatarsal head. Neuropathy, mechanical stress and vascular disease have been shown to be the primary causes of ulceration in patients with diabetes. Sensory neuropathy is considered the permissive cause of plantar ulceration. Plantar ulcerations do not occur without loss of sensation in the foot. Other factors including motor neuropathy, autonomic neuropathy, abnormal mechanical stress, foot deformity, joint limitation, and hyperkeratosis are considered important component causes in plantar ulceration. Autonomic neuropathy and vascular disease are trophic factors which cause tissues to be more susceptible to damage and ulceration, but are not direct causes. Motor neuropathy, foot deformity, joint limitation and hyperkeratosis are associated with high foot pressures. Individuals with high foot pressures and loss of protective sensation develop ulcerations from repeated injuries during walking. Plantar ulcerations commonly occur at the first metatarsal head. This study was conducted to determine if first ray joint limitation was related to ulceration at the first metatarsal head. Measurements of first ray mobility, pressure, and other physical measurements were made on 19 diabetic patients with a history of ulceration at the first metatarsal head, 20 diabetic patients with a history of ulceration at other locations of the forefoot, 19 matched diabetic, and 19 matched non-diabetic controls. Analysis of variance showed patients with a history of first metatarsal head ulceration had significantly lower first ray mobility and significantly higher pressure at the first metatarsal head compared to the other groups. Regression analysis showed a strong, negative, linear relationship between limited dorsiflexion of the first ray, and peak pressure and the pressure-time integral. Analysis of other physical measurements showed duration of diabetes was significantly higher, and sensation, range of motion at the hip, ankle and foot was significantly lower in patients with a history of ulceration compared to controls. The results demonstrate that the pathomechanical factors, limited joint mobility and high pressure, are significantly related to plantar ulceration and ulcer location in diabetes.