The Prediction of Diabetic Neuropathic Plantar Foot Ulceration by Liquid-Crystal Contact Thermography

Abstract

OBJECTIVE To assess whether the development of plantar foot ulceration could be predicted from the mean plantar foot temperature (MFT), as assessed by liquid-crystal contact thermography (LCT), in patients with peripheral neuropathy. RESEARCH DESIGN AND METHODS Fifty patients with painful diabetic sensorimotor neuropathy were studied prospectively. Initially, 30 patients had no significant peripheral vascular disease (PVD) (ankle:brachial systolic blood pressure ratio >1.0). LCT was used to assess the MFT from eight standard plantar sites. RESULTS Initial MFT was higher in the patients without PVD (28.2 ± 2.9°C, mean ± SD) than in patients with PVD (25.6 ± 1.9°C, P < 0.001) and in nondiabetic control subjects (25.7 ± 2.1°C, P < 0.001). At review, on average 3.6 (range 3.0–4.1) years later, 11 patients had died (6 of whom had PVD), and one was lost to follow-up. Six patients (seven feet) from the group without PVD had developed neuropathic plantar foot ulcers. The initial MFT was significantly higher in these seven feet (30.5 ± 2.6°C) than in the 38 feet of the 19 survivors in this group (27.8 ± 2.3°C, P < 0.01). Only one patient with PVD developed a plantar ulcer, although four required foot surgery for ischemie feet. CONCLUSIONS LCT is a simple, inexpensive, and noninvasive method of identifying the neuropathic foot at increased risk of ulceration. Patients with high plantar foot temperatures are at increased risk of neuropathic foot ulceration. A normal or low MFT in the neuropathic foot is a marker of PVD, which confers an increased risk of ischemie foot disease.