Different Design Feature Combinations of Flatfoot Orthosis on Plantar Fascia Strain and Plantar Pressure: A Muscle-Driven Finite Element Analysis With Taguchi Method.

Yinghu Peng,Guoxin Zhang,Yan Wang,Tony Lin-Wei Chen,Duo Wai-Chi Wong,Ming Zhang,Qitao Tan,Shane Fei Chen

doi:10.3389/fbioe.2022.853085

Abstract

Customized foot orthosis is commonly used to modify foot posture and relieve foot pain for adult acquired flexible flatfoot. However, systematic investigation of the influence of foot orthotic design parameter combination on the internal foot mechanics remains scarce. This study aimed to investigate the biomechanical effects of different combinations of foot orthoses design features through a muscle-driven flatfoot finite element model. A flatfoot-orthosis finite element model was constructed by considering the three-dimensional geometry of plantar fascia. The plantar fascia model accounted for the interaction with the bulk soft tissue. The Taguchi approach was adopted to analyze the significance of four design factors combination (arch support height, medial posting inclination, heel cup height, and material stiffness). Predicted plantar pressure and plantar fascia strains in different design combinations at the midstance instant were reported. The results indicated that the foot orthosis with higher arch support (45.7%) and medial inclination angle (25.5%) effectively reduced peak plantar pressure. For the proximal plantar fascia strain, arch support (41.8%) and material stiffness (37%) were strong influencing factors. Specifically, higher arch support and softer material decreased the peak plantar fascia strain. The plantar pressure and plantar fascia loading were sensitive to the arch support feature. The proposed statistics-based finite element flatfoot model could assist the insole optimization and evaluation for individuals with flatfoot.

Highlights

Individuals with flatfoot may demonstrate abnormal foot kinematics, such as excessive rearfoot eversion, collapsed foot arch, valgus forefoot, altered muscle activations, and potential symptoms (Richie Jr, 2007; Cifuentes-De la Portilla et al, 2019; Flores et al, 2019; Zhang and Lu, 2020)
The foot orthoses with higher arch support and medial inclination angle effectively reduced peak plantar pressure
This study investigated the influence of four orthosis design parameters configurations on foot pressure and plantar fascia loading at midstance

Summary

Introduction

Individuals with flatfoot may demonstrate abnormal foot kinematics, such as excessive rearfoot eversion, collapsed foot arch, valgus forefoot, altered muscle activations, and potential symptoms (e.g., knee pain and foot pain) (Richie Jr, 2007; Cifuentes-De la Portilla et al, 2019; Flores et al, 2019; Zhang and Lu, 2020). One of the most common conservative treatments, have been widely used to provide support, distribute the foot pressure, correct the flexible misalignment, and constrain the painful joints (Cobb et al, 2011; Telfer et al, 2013; Banwell et al, 2014; Kosonen et al, 2017). Foot orthoses with arch support are common considerations for redistributing plantar foot pressure and relieving foot pain (Cheung and Zhang, 2005). Previous studies have proposed and tested various foot orthoses for flatfoot, there is a lack of consensus on the foot orthoses design and their configurations on foot kinematics and kinetics (Cobb et al, 2011; Telfer et al, 2013; Banwell et al, 2014; Kosonen et al, 2017). Compared to prefabricated foot orthosis, customized foot orthoses can provide better functional outcomes in hindfoot correction and pain relief due to their consideration in individual variance (Cheung et al, 2011). Design feature combinations for the customized foot orthosis seriously depended on the experience of a pedorthist, lacking quantitative theoretical support

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