Trabecular Bone Poroelasticity for MicroCT-Based FE Models
A useful mathematical model that describes the mechanical behavior of bone is the poroelastic model. So far, numerical studies of trabecular bone poroelasticity have considered the tissue as a homogeneous porous structure. The objective of this study was
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Abstract A useful mathematical model that describes the mechanical behavior of bone is the poroelastic model. So far, numerical studies of trabecular bone poroelasticity have considered the tissue as a homogeneous porous structure. The objective of this study was to develop a methodology for creating large-scale finite element models that predict the poroelastic response of trabecular bone, including the tissue micro-architecture. 1 cm3 cubes of bovine trabecular bone were scanned using micro-computed tomography. Finite elements models were developed using different voxel and sample sizes. Strain equivalent to 1% of deformation was applied at three different rates and confined and unconfined conditions were simulated. Stress distributions in the bone phase were similar under confined and unconfined conditions. The fluid velocity and the pore pressure in the marrow were higher under confined than under unconfined conditions. The trabecular bone stiffness was higher under confined compared to under unconfined conditions, increasing with increments in the strain rate. Variations in the sample size were more significant in the predicted stiffness than variations in the voxel size. This study included both the poroelasticity and the micro-architecture of trabecular bone to predict changes in the mechanical response of trabecular tissue under time-dependent loading conditions.
C. Sandino () • S.K. Boyd Schulich School of Engineering, University of Calgary, Calgary, Canada Roger Jackson Centre for Health and Wellness Research, University of Calgary, Calgary, Canada McCaig Institute for Bone and Joint Health, University of Calgary, Calgary, Canada e-mail: [email protected]; [email protected] A. Wittek et al. (eds.), Computational Biomechanics for Medicine: Models, Algorithms and Implementation, DOI 10.1007/978-1-4614-6351-1 13, © Springer Science+Business Media New York 2013
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1 Introduction The poroelastic properties of trabecular bone play a critical role in the biomechanical response of bone tissue. Trabecular bone gives supporting strength to the ends of the weight-bearing bones, and this strength is related to the strain rate due to its poroelastic nature [4, 9]. Additionally, the inter-trabecular porous space is connected to the modularity cavity and is saturated with marrow, fat, and blood vessels. The marrow contains stem cells, which can differentiate into different phenotypes in order to generate tissue [3]. Trabecular bone poroelasticity has been studied at the macroscopic level [5]. At this level, trabecular bone tissue, which is formed by an interconnected structure of rods and plates saturated with marrow, is considered as a homogeneous material with specific properties describing its poroelastic behavior. Most of the studies have been focused on determining trabecular bone poroelastic properties [8, 11]. The study of Nauman et al. [11] demonstrated that the permeability of trabecular bone ranges over three orders of magnitude depending on the porosity and the ana
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