An orthopedic implant having an energy-harvesting device is disclosed. In one embodiment the orthopedic implant is a prosthetic component of a joint of the muscular-skeletal system. The orthopedic implant can include electronic circuitry, a power source, and one or more sensors for measuring a parameter of the muscular-skeletal system or a parameter of in proximity to the implant. The energy-harvesting device generates charge for powering the electronic circuitry using movement of the muscular-skeletal system. The energy-harvesting device comprises a piezo-electric element that converts changes in force into charge that is stored onto a storage device. The energy-harvesting device is coupled to the patella of a knee joint. Movement of the knee joint changes a force applied to the energy-harvesting device thereby generating charge that is coupled to circuitry in a prosthetic component of the knee joint.
