The Forefoot-to-Rearfoot Plantar Pressure Ratio Is Increased in Severe Diabetic Neuropathy and Can Predict Foot Ulceration

Abstract

OBJECTIVE—We have previously demonstrated that high plantar pressures can predict foot ulceration in diabetic patients. The aim of the present study was to evaluate both the relationship between forefoot and rearfoot plantar pressure in diabetic patients with different degrees of peripheral neuropathy and their role in ulcer development. RESEARCH DESIGN AND METHODS—Diabetic patients of a 30-month prospective study were classified according to the neuropathy disability score: scores of 0, 1–5, 6–16, and 17–28 are defined as absent (n = 20), mild (n = 66), moderate (n = 95), and severe (n = 57) neuropathy, respectively. The F-Scan mat system was used to measure dynamic plantar pressures. The peak pressures under the forefoot and the rearfoot were selectively measured for each foot, and the forefoot-to-rearfoot ratio (F/R ratio) was calculated. RESULTS—Foot ulcers developed in 73 (19%) feet. The peak pressures were increased in the forefoot of the severe and moderate neuropathic groups compared with the mild neuropathic and nonneuropathic groups (6.2 ± 4.5 and 3.8 ± 2.7 vs. 3.0 ± 2.1 and 3.3 ± 2.1 kg/cm² [mean ± SD], respectively; P < 0.0001). The rearfoot pressures were also higher in the severe and moderate neuropathic groups compared with the mild neuropathic and nonneuropathic groups (3.2 ± 2.0 and 3.2 ± 1.9 vs. 2.5 ± 1.3 and 2.3 ± 1.0, respectively; P < 0.0001). The F/R ratio was increased only in the severe group compared with the moderate and mild neuropathic and nonneuropathic groups (2.3 ± 2.4 vs. 1.5 ± 1.2, 1.3 ± 0.9, and 1.6 ± 1.0, respectively; P < 0.0001). In a logistic regression analysis, both forefoot pressure (odds ratio 1.19 [95% CI 1.11–1.28], P < 0.0001) and the F/R ratio (1.37 [1.16–1.61], P < 0.0001) were related to risk of foot ulceration, whereas rearfoot pressure was not. CONCLUSIONS—Both the rearfoot and forefoot pressures are increased in the diabetic neuropathic foot, whereas the F/R ratio is increased only in severe diabetic neuropathy, indicating an imbalance in pressure distribution with increasing degrees of neuropathy. This may lend further evidence toward the concept that equinus develops in the latest stages of peripheral neuropathy and may play an important role in the etiology of diabetic foot ulceration.