Abstract: A non-invasive, non-ionizing, reproducible method and apparatus for analyzing the normal and abnormal function of human and animal joints is presented. The method includes passing vibrations through the joint to be analyzed and measuring the modulation of the amplitude and the phase characteristics of the vibrations caused by movement of the joint through a predetermined cycle. More specifically, the method includes transmitting a sinusoidal vibratory signal through a joint structure to be analyzed and measuring the amplitude and phase of the signal received on the opposite side of the joint during a prescribed movement of the joint both with and without the application of external mechanical forces, and comparing the profile of the modulated signal to the profiles obtained from reference joints.