Nerve-muscle grafts in amputees for prosthesis control

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DESCRIPTION (provided by applicant): Currently transhumeral amputees can only operate a single degree-of-freedom at a time with myoelectric prostheses. This is very inadequate since multiple functions need to be controlled. We believe that the residual brachial plexus nerves in a transhumeral amputee can be grafted onto separate regions of the biceps, triceps and brachialis muscles and that these nerve-muscle grafts could provide additional myoelectric control signals that are physiologically related to the functions they would be controlling in the prosthesis. This would allow simultaneous control of multiple degrees-of-freedom with a more natural feel. The technique has great potential for improving the control of transhumeral myoelectric prostheses. A series of experiments have been performed that indicate the concept is feasible with a high probability of success. Since the muscles will be 'hyper-reinnervated' by the donor nerve, good muscle recovery is expected. Extensive EMG modeling studies indicate that surface EMG signals from the different nerve-muscle grafts will be able to provide discreet and independent control signals allowing simultaneous operation of a terminal device, elbow and wrist rotator. We propose a small, carefully orchestrated clinical trial of the nerve-muscle graft technique in recent transhumeral amputees. Baseline testing will be done with a conventional myoelectric prosthesis to measure operational performance. With IRB approval, surgery will be performed to denervate the medial head of the biceps and brachialis muscles, then graft the median and distal radial nerves on to these muscles. Once the muscles are reinnervated, the patient will be fit with an appropriately modified myoelectric prosthesis and trained in its use. The patient will then be able to use the nerve grafts to control a myoelectric hand and the lateral head of the biceps and the triceps to control the powered elbow. Performance testing will be repeated with the experimental myoelectric system for comparison to conventional measures.