Current techniques for bone lengthening and bone transport procedures rely primarily on transverse pins or wires for fixation and movement of the bone segments. These pins and wires are responsible for significant morbidity, specifically pain, scarring, loss of motion in regional joints, and pin site infection. A cable actuator is proposed that will eliminate percutaneous penetration of transfixing wires or pins and the associated pain, scars, contractures, & risk of infection. This actuator will enable a practical, fully implantable distraction device for application to bone lengthening and bone transport procedures. To ensure clinical success of the implant system, the actuator must be small, self-powered, automatic (actuate without active patient participation), and controllable (provide means for external clinical control and programming). Phase I will begin development of the actuator, and several engineering prototypes capable of generating a controllable distraction force of 1200 N will be built and tested. In Phase II, a final-form actuator will be developed and tested. This device will occupy less than 100 cc, be powered by a small, integrated battery, and be directed transcutaneously by a radio transmitter. PROPOSED COMMERCIAL APPLICATIONS: Approximately 15,000 to 20,000 procedures are performed annually to replace or regenerate missing bone segments over 2.5-cm long. There are about 6,000 limb lengthenings performed annually. About one-third of these would be candidates for this system. The proposed design is advantageous compared to other approaches because the mechanism is located remotely, relative to the bone, with the force transmitted by a cable. Therefore, a standard intermedullary rod can be implanted, and the system can be applied to any bone amenable to rod fixation.