Implantable sensors and methods for detecting changes in a characteristic of a soft tissue is disclosed. In one embodiment, an implantable sensor for detecting indicators of cartilage wear in a joint is provided. The implantable sensor includes a sensing element for detecting a signal indicative of a characteristic of the cartilage of the joint and a telemetry circuit in communication with the sensing element for transmitting a data set representative of the detected signal. In another embodiment, a system for detecting changes in joint cartilage includes an implantable acoustic sensing element and an external receiver in communication with the implantable acoustic sensing element. In other embodiments, methods of detecting cartilage degradation in a joint and methods of using the disclosed sensors are provided.
