The Evaluation of Stress Distribution of the Different Layers in Rearfoot Plantar Soft Tissue during Stance Phase

• Main Authors: I-Kuei Liu, 劉奕奎
• Other Authors: Weng-Pin Chen
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/48741293827914309854

碩士 === 中原大學 === 醫學工程研究所 === 96 === Based on the anatomical definition, the human heel fat pad consists of the microchamber layer lying beneath the plantar skin and the macrochamber layer lying near the calcaneus. In previous studies, the heel pad is often considered as a simple structure with homogeneous material owing to some simplifications and limitations. There is few study investigated the biomechanical behavior of the heel pad with both the microchamber and macrochamber layers during human locomotion. Therefore, the purpose of this study was to evaluate the biomechanical behavior of the detailed plantar heel soft tissue structure during stance phase by finite element analysis. In order to construct the detailed finite element model of the rearfoot, magnetic resonance imaging (MRI) system was used to capture the right foot images from a healthy male subject. A specially-designed loading device was integrated with an ultrasonic imaging system to measure the material properties of different plantar soft tissue layers as well. Motion analysis was performed to obtain the kinematic and kinetic data of the right foot of the same subject who received MRI scanning. Finally, the results from finite element analysis were compared with the data from plantar pressure measurement to verify the accuracy of computer simulation. The result show that the maximum stress which concentrated around the medial calcaneal tuberosity was about 250 KPa. Moreover, there was a high shear stress of 150 KPa found in the inner soft tissue. About 90% of the heel fat pad strain was found in the macrochamber layer when the plantar soft tissue was subjected to loading. On the other hand, only about 10% of the heel fat pad strain was found in the microchamber layer. Therefore, when considering the plantar soft tissue as a nonhomogeneous material not only can present the realistic loading response of the plantar soft tissue, but also show similar strain results from both finite element analysis and experimental measurement. For this reason, the presented quantitative data in the current study can provide meaningful reference for the prevention and treatment of foot disease for clinical applications.