The thicknesses of bone and bone marrow within a pig femur inserted with a metal stem of the total hip replacement system are investigated non-destructively by means of an ultrasonic technique. First, the wave velocities of bone and bone marrow are determined using the pulse echo method and thereby observing the time intervals between the first and the second echoes in these specimens. Next, an ultrasonic wave is emitted toward the femur inserted with the metal stem which is immersed in a water tank, and the distances from a normal probe to the boundary surfaces of bone and metal stem are measured. Subsequently, the actual thicknesses of the bone and the bone marrow are measured using vernier calipers. These measured results using the ultrasonic wave and the vernier calipers are compared and are graphically presented. Thus, the ultrasonic method is practically useful for the measurement of the bone and the bone marrow within the femur inserted with the metal stem.
