In vitro measurements of the lateral wave in human cortical bone

Ultrasonic wave propagation in human cortical bone has been investigated in vitro using an axial transmission technique. Two quasi-point source elements, one transmitter and one receiver, were used to generate a wide ultrasonic beam including the longitudinal critical angle and to receive the signals radiated from the sample surface. Validation of the measuring technique was performed on test materials, followed by experiments on human cortical bones. Velocity measurements of the first arriving signal based on time-of-flight determinations were in agreement with reported values of longitudinal velocities for both test materials and bone specimens, and so did the experimental arrival times of the first arriving signal and ray arrival times of the lateral wave. The velocity in cortical bone ranged from 3600 to 4050 m.s/sup -1/. Our results strongly suggest that the first arriving signal corresponds to the lateral wave predicted by theory.