Effect of Cortical Bone Layer on Fast and Slow Waves in Cancellous Bone: Investigations Using Stratified Models

Abstract

Fast and slow longitudinal waves can propagate through cancellous bone in the direction of the strong trabecular orientation. In in vivo experiments, the cortical bone layer surrounding cancellous bone is considered to affect the fast and slow wave propagations. In this study, the effects of the cortical bone layer were investigated using the stratified models of cancellous bone. In the experimental and simulated results, it was shown that the boundary condition between the cancellous and cortical bone regions affected both the fast and slow waves, particularly the slow wave. The slow wave could be clearly observed for the stratified bone model with a distinct boundary, but the slow wave amplitude decreased as the boundary became less distinct. This was because the generation of the slow wave was interrupted by the gradually varying pore spaces. Moreover, it was shown that the reflected waves within the cortical bone layer could affect the observation of the fast and slow waves. Despite the effects of the cortical bone layer, both the fast and slow waves could be observed for all stratified bone models.