Affiliations: [a] Research Center for Science and Technology in Medicine, Tehran Medical Science University, Emam Khomeini Hospital, Keshavarz Bulvard, Tehran, Iran. E-mail: zbarani_2000@yahoo.com | [b] Department of Mechanics, Iran University of Science and Technology, Tehran, Iran. E-mail: mhaghpanahi@yahoo.com | [c] Biomedical Engineering Department, AmirKabir University of Technology, Tehran, Iran. E-mail: katoozian@engineer.com
Correspondence:
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Corresponding author.
Abstract: Current research in foot biomechanics includes studies on prevention of recurrence of neuropathic foot ulcers. This paper attempts to prescribe accommodative insoles, which reduce plantar pressure levels particularly under the hallux. There is little quantitative information available regarding the effects of insole materials on reduction of plantar pressure. The insole models available in the literature are mostly two-dimensional (2-D). Hence, there is a need to develop a 3-D model with actual geometry which includes sufficient details. In this study a three-dimensional (3-D) model of the insole was constructed. A linear and non-linear static analysis using finite element method (FEM) was performed. Results were compared for different materials such as Silicon Gel, Plastozot, Polyfoam, and Ethinil Vinyl Acetate (EVA). Our 3-D finite element model was constructed using 16170 ten-node tetrahedral, mixed U-P (displacement-pressure), hyperelastic, solid elements. Four different hyperelastic and foam materials were used and compared and the loading condition was based on the mid-stance phase of the gait. This research has shown that most of these materials are very effective in terms of reduction of plantar stress concentrations. The technique used in this research provides a promising approach to understanding of behavior of insole materials and suggests a design guideline for therapeutic footwear and orthoses.
Keywords: diabetic insoles, silicon gel, plastozot, polyfoam, ethinil vinyl acetate (EVA), hyperelasticity, three dimensional FEM
