The effect of structural anisotropy on the fast wave propagation in cancellous bone.

Abstract

QUS parameters are closely related to the structural properties and elastic properties of bone, which can provide important information related to bone quality and bone strength. One should be very careful, however, that bone contains complicated structure from microscopic to macroscopic levels. For example, the cancellous bone inside the epiphysis is composed of a complicated trabecular network in the bone marrow, showing strongly anisotropic and heterogeneous structure. We have then observed the longitudinal wave propagation in this complicated medium, paying special attention to the two wave phenomenon. The fast wave, which mainly propagates in the trabecular part of the cancellous bone, is more sensitive to the network structure. With the help of x-ray micro-computed tomography, three dimensional anisotropic trabecular structure and fast wave propagation were investigated using bovine cancellous bones. We can find the strong effect of anisotropic trabecular structure on the fast wave velocity. The mean intercept length (the information of average trabecular length) was a good parameter to describe the three dimensional trabecular structure and showed good correlation with the fast wave velocity.