Stress Distribution in Human Tibia Bones using Finite Element Analysis

Abstract

This paper presents the accuracy of finite element models of human tibia bones generated from CT-images used for analyzing stress distribution under loading. The effects of bone structures and material properties (isotropic and orthotropic materials) on stress distribution during stance phrase running were studied. Three-dimensional tibia models were constructed by using Mimics V.10.01, Geomagic V.10 and Catia V.5 software. Then these models were imported into the Hypermesh V.12 software to generate the FE models. Finally the FE models are imported to ANSYS (APDL) V.14.5 software to analysis the stress distribution in the tibia bones. By compared to the benchmark FE model of tibia bones (case studies 13 and 14) resembling to the real bone, we found that there were two sites of maximum von Mises stresses found on tibia bones which were on the middle of posterior tibia and the proximal tibia. However, FE models formed only by cortical bone could not capture the peak stresses on the proximal tibia due to the lack of relatively soft subsurface. The FE models with the medullary cavity formed by cortical bone over predicted the maximum von Mises stress on the middle of posterior tibia while ones with the medullary cavity formed by cancellous bone, bone marrow or bone marrow fat obtained quite similar results. The bone marrow fat in the medullary cavity could not assist to support load on the proximal tibia due to the relatively soft material. The maximum von Mises stresses obtained from FE models with cortical bone formed by orthotropic material were slightly different from ones formed by isotropic material. However, the difference of these FE results was directional cosines that indicated the direction of the crack initiation.