Clawed toes in the diabetic foot: neuropathy, intrinsic muscle volume, and plantar aponeurosis thickness

Abstract

Clawed toes, defined as extension of the metatarsophalan- geal joint (MTPJ) and flexion of the proximal and distal interphalangeal joints (IPJ), have been associated with the diabetic foot. One theory states that this deformity is caused by an imbalance between the extrinsic and intrin- sic foot muscles [1,2]. However, Bus et al. found a 73% decrease in intrinsic muscle cross sectional area between diabetic neuropathic patients and controls, but only 2 of 8 neuropathic patients had toe deformities [3]. Anderson et al. found that diabetic neuropathic patients had a little more than 50% of the intrinsic muscle volume of either controls or non-neuropathic diabetic patients, but none of the diabetic neuropathic patients had toe deformities [4]. Others have found a link between plantar aponeurosis (PA) dysfunction and clawed toes [5,6] and between diabetes and a thicker PA [7-9]. The purpose of this study was to explore the relationship between claw toes, neuropathy, intrinsic muscle volume and PA thickness.