Micro-Finite Element Model for Bone Strength Prediction - Computational Biomechanics of the Musculoskeletal System - page 323

24 Micro-Finite Element Model

for Bone Strength Prediction

He Gong, Ming Zhang, and Ling Qin

ContentS
Summary ........................................................................................................................................ 323
24.1 Introduction ......................................................................................................................... 323
24.2 Development of a Micro-Finite Element Model for Bone Strength Prediction .................. 324
24.2.1 Micro-CT Scanning Procedure ............................................................................. 324
24.2.2 Three-Dimensional Modeling of Trabecular Specimens ...................................... 324
24.2.3 Nonlinear Micro-Finite Element Analysis ............................................................ 324
24.3 Results from the Model Analysis ........................................................................................ 326
24.4 Applications of the Model ................................................................................................... 327
Acknowledgments .......................................................................................................................... 330
References ...................................................................................................................................... 330

Summary
A quantitative assessment of trabecular bone strength at the tissue level is essential for understand-
ing bone failure mechanisms associated with osteoporosis, osteoarthritis, loosening of implants,
and cell-mediated adaptive bone remodeling. The material properties of the trabeculae, in combi-
nation with their microarchitectures at the tissue level, determine the strength of trabecular bone.
Micro-CT (computed tomography) image-based micro-finite element analysis takes most determi-
nants of trabecular bone strength into consideration, such as the material properties of the trabeculae
and their micro-architectures. Under large loading conditions, bone tissue material nonlinearity and
large deformations within the trabecular network, such as bending and buckling, are important for
the characterization of the apparent and tissue-level failure behaviors. In this chapter, two trabecular
specimens with different microstructures are used as examples to illustrate a numerical technique
that offers a better understanding of trabecular yield behaviors under different loading directions.

24.1 introduction
There are two types of bones in the skeleton: dense, compact cortical bone and porous, spongy
trabecular bone. Trabecular bone is located inside cortical bone shells and responds faster to bio-
physical stimuli, and thus is most susceptible to osteoporosis, particularly in the elderly popula-
tion (Melton et al., 1992). Tissue level trabecular bone strength is essential for understanding bone
failure mechanisms, which is determined by the material properties of trabeculae in combination
with their microarchitectures at the tissue level. Direct mechanical tests on trabecular specimens
have been used to obtain the mechanical properties of trabecular bone (Morgan et al., 2003).
However, mechanical tests can be performed on each specimen only once due to the tests' destruc-
tive nature. Alternatively, with enhanced computational power and advanced imaging techniques,
mechanical tests can be simulated by micro-finite element analysis (also written as μFEA) based on

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