Plantar soft-tissue thickness predicts high peak plantar pressure in the diabetic foot.

Abstract

The aim of this study was to evaluate whether high plantar foot pressures can be predicted from measurements of plantar soft-tissue thickness in the forefoot of diabetic patients with neuropathy. A total of 157 diabetic patients with neuropathy and at least one palpable foot pulse but without a history of foot ulceration were invited to participate in the study. Plantar tissue thickness was measured bilaterally at each metatarsal head, with patients standing on the same standardized platform. Plantar pressures were measured during barefoot walking using the optical pedobarograph. Receiver operating characteristic analysis was used to determine the plantar tissue thickness predictive of elevated peak plantar pressure. Tissue thickness cutoff values of 11.05, 7.85, 6.65, 6.55, and 5.05 mm for metatarsal heads 1 through 5, respectively, predict plantar pressure at each respective site greater than 700 kPa, with sensitivity between 73% and 97% and specificity between 52% and 84%. When tissue thickness was used to predict pressure greater than 1,000 kPa, similar results were observed, indicating that high pressure at different levels could be predicted from similar tissue thickness cutoff values. The results of the study indicate that high plantar pressure can be predicted from plantar tissue thickness with high sensitivity and specificity.