Method and apparatus for evaluating osteointegration of medical implants

Ultrasound vibrometry is employed to determine the amount of bony in-growth (i.e., osteointegration) into a surgically implanted prosthetic component (or conversely, the degree of implant looseness). While specifically developed for assessing osteointegration for total ankle replacements, the technique has broader application to any joint arthroplasty device. With respect to ankle arthroplasty, a vibration is induced in a patient's ankle in a range of frequencies. A Doppler ultrasound unit scans the ankle, with an imaging plane focused on an implant surface. The vibrations input into the ankle are sinusoidal frequencies, in a range from 80-500 Hz. At a frequency determined to best facilitate vibration of the ankle (e.g., a resonant frequency), the output signal from the Doppler ultrasound is Fourier transformed so that the frequency components of the output signal can be observed. These output Fourier signatures have been shown to correspond to a graded response of implant osteointegration (or looseness).