Prediction of anisotropic trabecular orientation and spatial distribution of anabolic remodeling by acoustic wave propagation

The microarchitecture of trabecular bone results from adaptation by the mechanical milieu applied to it. Characteristics of such anisotropic mechanical property can further understand adaptive response of bone to the particular mechanical loading and predict risk of fracture. Quantitative ultrasound (QUS) has demonstrated its ability to predict the principal structural orientation (PSO) of trabecular bone. It remains unknown whether the structural orientation would associate with mechanical strength of bone. The objective of this study was to evaluate the mechanical properties in different PSOs predicted using various methods (i.e., QUS and μCT), thus, to investigate the ability of QUS as a means to predict the PSO of trabecular bone noninvasively. Seven trabecular bone balls from distal bovine femurs were used for QUS tests, and to generate finite element analysis based on the 3-D μCT images. The stiffness in the PSOs predicted by QUS were highly correlated with the stiffness in the MIL tensor orientation (ATT vs. MIL, R 2=0.97, p<0.001; UV vs. MIL, R2=0.92, p<0.001).