Implantable bone growth stimulator

Abstract

Disclosed is an implantable bone growth stimulator which needs no internal battery or large buffer capacitor. A receiving coil in a preferred embodiment, a ferrite core coil, receives RF energy from a transmitter external to the patient. The received RF energy is voltage doubled and rectified and provided to a constant current generator which in turn supplies a constant amount of current between implanted cathodes and an implanted anode. In preferred embodiments, the receiving coil, power supply, and cathodes are one unit which is located in place on an internal fixation device attached to the bones near the fracture site. In another embodiment, only the cathodes are located in the vicinity of the fracture site and the receiver coil voltage multiplier circuit and constant current source are located remote from the fracture site. Additionally, the internal fixation device in a preferred embodiment may have a plastic insert therein having one or more holes therethrough for the insertion of cathodes into the vicinity of the fracture site. While a preferred embodiment utilizes the completely implanted bone growth stimulator, the plate is effectively utilized with an external bone growth stimulator power supply and percutaneous cathodes inserted through positioning holes in the plastic insert of the fixation device.