µCT/HR-pQCT Image Based Plate-Rod Microstructural Finite Element Model Efficiently Predicts the Elastic Moduli and Yield Strength of Human Trabecular Bone

Osteoporosis is an age-related disease characterized by low bone mass and architectural deterioration, which affects primarily the trabecular sites and causes millions of fractures. High-resolution image voxel-based finite element (FE) models with the detailed 3D microstructure have been widely utilized to assess the mechanical properties of trabecular bone [1, 2]. However, the very large size of the voxel-based FE model, in general, limits its application to linear elastic cases. Despite the great potential it has shown in studying trabecular bone failure, iterative nonlinear analysis is still hard to be performed efficiently. Therefore, there is an apparent need for an alternative approach, which maintains the advantages of the voxel-based FE models in capturing details of trabecular microstructure, while allowing faster computation. Based on the individual trabeculae segmentation (ITS) technique [3], a specimen-specific plate-rod (P-R) microstructural FE model was developed by substituting the individual beam/shell element for 3D volume of trabecular plate/rod of μCT images of trabecular bone (21 μm resolution) (Fig. 1). The first goal of this study is to validate both linear and nonlinear predictions based on the P-R models for in vitro μCT images of human trabecular bone samples. The prediction accuracy and computational speed of the P-R model were examined by comparing with those of the voxel-based FE model.