Plantar soft tissue homogeneity in ulcerated vs non-ulcerated feet using strain elastography

Background: Homogeneity (or in-homogeneity) of plantar soft tissues affects stress distribution inside the sole of the foot with significant implications in people with diabetic neuropathy as mechanical trauma is considered the main cause of foot ulceration in this population. While ultrasound strain elastography has been recently used to assess deformability of the plantar soft tissue (Lin et al., 2015; Matteoli et al., 2015), there is a paucity of studies assessing the homogeneity of plantar soft tissue using this data. Aims: To propose a method to quantify the homogeneity of plantar soft tissues and to investigate the differences in heel pads homogeneity between ulcerated and non-ulcerated feet. Methods: 5 diabetic (type-2) neuropathic patients with unilateral foot ulceration on the forefoot were included in this study. Strain elastography, (Esaote S.p.A., IT) was used to assess the deformability of the heel pad. A custom image-processing algorithm was developed to quantify changes in deformability between neighbouring pixels using central difference method. The average values and standard deviation of the aforementioned differences were calculated as non-homogenous indices along depth, breadth, and the oblique direction in the imaging plane. Results: The ulcerated feet showed higher homogeneity, indicated by observed higher average deformability gradient in depth, breadth and oblique directions. Summary: The homogeneity profile of plantar soft tissue in ulcerated feet appear to be different compared to non-ulcerated feet with possible implications in diagnosing tissue vulnerability and mechanical trauma in people with diabetic foot disease.