Peak Plantar Pressure and Shear Locations

Diabetic foot ulcers burden the U.S. health care system with an annual cost of approximately $6 billion (1). Based on the mechanical etiology of diabetic foot lesions, investigators tried to establish a relationship between ulcer occurrence and plantar pressures. Mostly, peak pressure has been chosen as an ulcer predictor. However, previous studies have yielded only moderate correlations between peak pressure and the occurrence of diabetic foot lesions (2–4). Surprisingly, in one study that examined whether plantar ulcer locations matched peak pressure sites (4), only 38% of the ulcers developed under the peak pressure area. Therefore, foot pressure was labeled as a “poor” predictor of diabetic ulcer occurrences and their location (3). Effectiveness of diabetic ulcer prediction and prevention depends on an understanding of plantar soft tissue mechanics and the complete nature of foot-ground interactions. Further investigation of plantar shear in addition to pressure is essential to minimize the neuropathic ulcer prevalence. The purpose of this study was to find whether the peak pressure and shear under the feet of diabetic patients occur at different locations. If confirmed, shear distribution may explain the deviation between peak pressure and ulcer locations and potentially help researchers design more effective interventions. Thirty volunteers were recruited, among whom 10 had diabetic neuropathy. The remaining nondiabetic subjects served as control subjects. Subjects with gross foot deformities (except minor toe clawing), prior foot surgeries, and …