Neuropathy, Claw Toes, Intrinsic Muscle Volume, and Plantar Aponeurosis Thickness in Diabetic Feet

Abstract Background: The objective of this study was to explore the relationship between claw toe deformity, peripheral neuropathy, intrinsic muscle volume, and plantar aponeurosis thickness using computed tomography (CT) images of diabetic feet. Methods: Forty randomly-selected subjects with type 2 diabetes were selected for each of the following four groups (n = 10 per group): 1) peripheral neuropathy with claw toes, 2) peripheral neuropathy without claw toes, 3) non-neuropathic with claw toes, and 4) non-neuropathic without claw toes. The intrinsic muscles of the foot were segmented from processed CT images. Plantar aponeurosis thickness was measured in the reformatted sagittal plane at 20% of the distance from the most inferior point of calcaneus to the most inferior point of the second metatarsal. Five measurement sites in the medial-lateral direction were utilized to fully characterize the plantar aponeurosis thickness. A linear mixed effects analysis on the effect of peripheral neuropathy and claw toe deformity on plantar aponeurosis thickness and intrinsic muscle volume was performed. Results: Presence of claw toe deformity ( p = 0.008) and presence of neuropathy ( p = 0.039) were both associated with decreased intrinsic muscle volume. Subjects with both neuropathy and claw toe deformity had significantly thicker plantar aponeurosis tissue compared with the other three permutation subgroups ( p < 0.001). A negative correlation was observed between plantar aponeurosis thickness and intrinsic muscle volume ( R 2 = -0.3233, p < 0.001). Conclusions: In subjects with claw toe deformity, there were strong relationships between smaller intrinsic foot muscle volumes and thicker plantar aponeurosis tissue. Intrinsic muscle atrophy and plantar aponeurosis thickening may be related to the development of claw toes.