Numerical investigation of ultrasound wave propagation in cancellous bone with oblique trabecular orientation

Two longitudinal waves of “fast and slow waves” propagating through cancellous bone can be separately observed in the case of the trabecular structure oriented parallel to the wave propagation, but a single wave, in which the fast and slow waves completely overlap, can be observed in the case of the perpendicularly oriented structure. This can be considered to be because the propagation paths of the fast and slow waves in these cases are different. In this study, the changes in the propagation paths (or directions) with the angle of the trabecular orientation have been numerically investigated using finite-difference time-domain simulations with realistic cancellous bone models reconstructed from a three-dimensional microcomputed tomographic image. The simulated results suggested that both propagation paths changed owing to the oblique trabecular orientation, which could affect the structural dependences of the propagation properties.