Effects of tissue heterogeneity on trabecular micromechanics examined by microCT-based finite element analysis and digital volume correlation

Trabecular bone is natural material with heterogeneous tissue properties. The effect of tissue heterogeneity on the micromechanical behavior of trabecular bone is commonly evaluated by microCT-based finite element (microFE) analysis. Results from prior work remain inconclusive and lack of experimental validation. To address these issues, we combined microFE analysis with mechanical testing and microCT-based digital volume correlation (DVC), as a validation for the microFE approach. Porcine trabecular specimens were tested in compression as sequential microCT scans were taken. DVC was performed to extract “realistic” boundary conditions that were applied to microFE models, and to measure microstructural deformation and strain of the trabecular specimens. Heterogeneous and homogeneous microFE models of each trabecular specimen were created and compared with the experimentally measured microstructural displacement and strains. Results showed strong correlations between DVC-measured and microFE-predicted trabecular displacement and strain fields (R² ​> ​0.9, p ​< ​0.05), regardless of heterogeneous or homogeneous material assignments. The heterogeneous and homogeneous models predicted similar magnitudes for maximum or minimum principal strains (R² ​= ​1, p ​< ​0.05). However, incorporation of tissue heterogeneity decreased more than 16.5% in the overall stress level of the trabecular tissues. Regardless, very strong correlations were found between the heterogeneous and homogeneous model-predicted principal strains or stresses. These results together suggest that tissue heterogeneity may have little effect on microFE modeling of typical elastic displacement and strains in the trabecular bone, suggesting that homogeneous material models might be sufficient to predict general trabecular micromechanics.