Plantar fat-pad displacement in neuropathic diabetic patients with toe deformity: a magnetic resonance imaging study.

OBJECTIVE: The aim of this study was to quantify the association between claw/hammer toe deformity and changes in submetatarsal head (sub-MTH) fat-pad geometry in diabetic neuropathic feet. RESEARCH DESIGN AND METHODS: Thirteen neuropathic diabetic subjects (mean age 56.2 years) with toe deformity, 13 age- and sex-matched neuropathic diabetic control subjects without deformity, and 13 age- and sex-matched healthy control subjects without deformity were examined. From high-resolution sagittal plane magnetic resonance images of the second and third ray of the foot, toe angle (a measure of deformity), sub-MTH fat-pad thickness, and subphalangeal fat-pad thickness were measured. The ratio of these thicknesses was used to indicate fat-pad displacement.
RESULTS: Sub-MTH fat pads were significantly thinner (2.5 +/- 1.3 vs. 6.0 +/- 1.4 mm, P < 0.001) and subphalangeal fat pads significantly thicker (9.1 +/- 1.9 vs. 7.6 +/- 1.2 mm, P < 0.005) in the neuropathic group with deformity compared with neuropathic control subjects. As a result, thickness ratio was substantially smaller in the deformity group: 0.28 +/- 0.14 vs. 0.79 +/- 0.14 in neuropathic control subjects (P < 0.001). A significant correlation of 0.85 was present between toe angle and thickness ratio (P < 0.001). No significant differences were found between neuropathic and healthy control subjects.
CONCLUSIONS: This study shows a distal displacement and subsequent thinning of the sub-MTH fat pads in neuropathic diabetic patients with toe deformity and suggests that, as a result, the capacity of the tissue in this region to reduce focal plantar pressure is severely compromised. This condition is likely to increase the risk of plantar ulceration in these patients. Copyright 2004 American Diabetes Association