PURPOSE: Myoelectric prosthetic limb function is inadequate for transhumeral amputees, because residual biceps and triceps are required to sequentially control the elbow, wrist and hand. We present the results of a new technique, termed targeted reinnervation, that employs multiple nerve transfers to reestablish the activity of the otherwise functionless median, and distal radial nerves for control of the myoelectric prosthesis.

METHOD: Targeted reinnervation surgery was performed on three patients with transhumeral amputations. The median nerve was transferred to the denervated medial head of the biceps and the distal radial nerve was transferred to the denervated brachialis muscle to control terminal device closing and opening, respectively. Each patient was fit with a conventional prosthesis prior to surgery and a modified, experimental prosthesis a few months after surgery when reinnervation was clinically evident. Objective functional testing of the patient was performed both before and after nerve transfer surgery.

RESULTS: Two of the three patients had successful nerve transfers reflected by clinical examination and marked improvements in functional testing. Blocks and Box scores increased from 2.5 to 7 fold while time to complete clothespin relocation testing was reduced by close to half in both patients. Assessment of motor and processing skills (AMPS) testing and other activities of daily living (ADL) were performed at substantially higher speeds and with greater ease using the experimental prosthesis when compared to the conventional prosthesis. The third patient did not have a successful experimental surgery due to a more proximal nerve injury.

CONCLUSION: Through the use of targeted muscle reinnervation in transhumeral amputees, two additional control signals may be created that objectively and subjectively improve prosthetic arm function. These signals allowed for simultaneous, intuitive control of the prosthetic hand and elbow.