The prediction of diabetic neuropathic plantar foot ulceration by liquid-crystal contact thermography.

Abstract

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. 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. Initial MFT was higher in the patients without PVD (28.2 +/- 2.9 degrees C, mean +/- SD) than in patients with PVD (25.6 +/- 1.9 degrees C, P < 0.001) and in nondiabetic control subjects (25.7 +/- 2.1 degrees 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 degrees C) than in the 38 feet of the 19 survivors in this group (27.8 +/- 2.3 degrees C, P < 0.01). Only one patient with PVD developed a plantar ulcer, although four required foot surgery for ischemic feet. 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 ischemic foot disease.