In vivo measurements of the phase constants of transverse mechanical waves in a human tibia from 100 to 1000 Hz.

This paper contains the details of a new technique for measuring the mechanical phase constants of transverse waves in human tibia, in vivo. The measurements are made in the frequency range from 100 to 1000 Hz. The importance of these measurements is that healthy tibia has quite small phase delays along the bone at these frequencies. On the other hand, a fractured tibia has a large phase delay at the fracture site. This paper establishes a set of typical phase delays for a range of tibia so that subsequent measurements on fractured patients can be interpreted. It contains a description of the method of measuring the phase delay and a detailed analysis of errors. In particular, it includes an account of the phase delay through the soft tissues as well as the bone and how the former can be eliminated. It is not an exhaustive account of this topic but contains sufficient results to show that the measurements can be made relatively easily. Finally, there is a theoretical model which can be used to predict the phase shift. However, in order to use the model various other measurements are necessary and a direct measurement of phase is easier than using a model.