Finite element modeling to estimate the apparent material properties of trabecular bone

The in-vivo micro-structure and corresponding material property of trabecular bone is important to simulate the mechanical behavior of macroscopic bone structure. In order to simulate the mechanical behavior of bone numerically, the apparent Young's modulus of trabecular bone should be available. Generally a high-resolution finite-element model based on micro-CT-images could be was used to estimate this value. However, all the previous works regarding this issue have employed either eight-noded voxel elements or four-noded tetrahedral elements, which usually produces large amount of error in estimating an apparent material property. Therefore, rigorous studies on the accuracy of element type for predicting the material properties of cancellous bone have been made in this paper. Micro-CT-data were extracted from a femoral neck to construct three-dimensional finite-element models with three different element types and compression analyses were performed numerically (up to 1.3% strain) to estimate the apparent modulus. Compression tests using the specimens extracted from a cadaver were also performed to validate the simulated apparent material properties using different element types. As a result, ten-noded tetrahedral elements are recommended to obtain reliable material properties of cancellous bone instead of eight-noded voxel elements or four-noded tetrahedral elements.