Experimental Analysis of Plantar Fascia Mechanical Properties in Subjects with Foot Pathologies

Silvia Todros,Piero G Pavan,Carlo Biz,Pietro Ruggieri

doi:10.3390/app11041517

Abstract

Plantar Fascia (PF) is a fibrous tissue that plays a key role in supporting the foot arch; it can be affected by several pathologies that can alter foot biomechanics. The present study aims at investigating the mechanical behavior of PF and evaluating possible correlations between mechanical properties and specific pathologies, namely diabetes and plantar fibromatosis (Ledderhose syndrome). PF samples were obtained from 14 human subjects, including patients with Ledderhose syndrome, patients affected by diabetes and healthy subjects. Mechanical properties of PF tissues were evaluated on three samples from each subject, by cyclic uniaxial tensile tests up to 10% of maximum strain and stress relaxation tests for 300 s, in hydrated conditions at room temperature. In tensile tests, PF exhibits non-linear stress–strain behavior, with a higher elastic modulus (up to 25–30 MPa) in patients affected by Ledderhose syndrome and diabetes with respect to healthy subjects (elastic modulus 10 ÷ 14 MPa). Stress-relaxation tests show that PF of patients affected by Ledderhose syndrome and diabetes develop more intense viscous phenomena. The results presented in this work represent the first experimental data on the tensile mechanical propertied of PF in subjects with foot diseases and can provide an insight on foot biomechanics in pathological conditions.

Highlights

The Plantar Fascia (PF) is a connective tissue composed of type I collagen fibers arranged in a longitudinal direction, elastic fibers and an extracellular matrix highly rich in hyaluronan [1]
In the present work the results of experimental tests on the nonlinear stress–strain and time-dependent behavior of PF show a tendency of plantar tissue in patients affected by Ledderhose syndrome and diabetes to be stiffer than the one in healthy subjects and to develop more intense stress-relaxation phenomena
The reduced number of samples considered in the present investigation comes from the evident difficulty in obtaining the PF from subjects that undergo foot excision due to Ledderhose disease or diabetes

Summary

Introduction

The Plantar Fascia (PF) is a connective tissue composed of type I collagen fibers arranged in a longitudinal direction, elastic fibers and an extracellular matrix highly rich in hyaluronan [1]. The most common pathological condition that the PF can undergo is plantar fasciitis [9], which typically affects workers and athletes whose activities have a high impact on the foot, causing inferior heel pain [10,11] Another pathology affecting the PF is plantar fibromatosis, called Ledderhose disease, which is a benign nodular formation usually in the medial part of the PF causing pain during gait [12,13]. Recent studies have focused on the importance of understanding the biomechanics of the diabetic foot to define the appropriate treatment and prevent complications for each of its different pathological aspects [19,20] This investigation must involve the PF, as one of the elements of the foot region assuming distinctive structural behavior. A selective PF release has been suggested to redistribute the pressure on the sole for healing forefoot chronic ulcers in diabetic patients [21]

Methods

Results

Conclusion