TARGETED REINNERVATION TO IMPROVE MYOELECTRIC PROSTHESIS FUNCTION

这个子项目是众多研究子项目之一

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Currently, upper limb 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, especially with high-level amputations such as transhumeral (TH) and shoulder disarticulation (SD). Furthermore, they have no feeling with a prosthesis - the only feedback they receive is visual feedback from watching the arm and a bit of auditory feedback from hearing the motors. Using a technique we have developed, called 'Targeted Reinnervation', we have demonstrated that the residual arm nerves in amputees can be transferred onto separate regions of muscle and that the reinnervated muscle can provide additional myoelectric control signals that are physiologically related to the functions they would be controlling in the prosthesis. This allows simultaneous control of multiple degrees-of-freedom with a more natural feel. The technique has great potential for improving the control of myoelectric prostheses. Furthermore, the potential exists for important tactile sensory feedback by reinnervating skin in the residual regions with hand nerves. By placing sensors in the prosthetic hand and giving pressure over the reinnervated skin, the amputee actually perceives how hard he or she is squeezing with the prosthetic hand as if it were in their missing hand. Our first series of four patients has been very successful. One subject with a SD and 2 of 3 TH amputees have had successful targeted motor reinnervation. This has allowed them to simultaneously control their powered hands and elbows using physiologically appropriate nerve signals. The SD patient has also had targeted reinnervation such that he can feel light touch, graded pressure, sharp/dull and even hot and cold in his missing limb when touched on his chest. We propose a continued, carefully orchestrated clinical trial of the targeted reinnervation technique in recent TH and SD amputees to refine the procedure. Baseline testing will be done with a conventional myoelectric prosthesis to measure operational performance. With IRB approval, surgery will be performed to denervate muscles, or parts of muscles, in or near the residual limb and transfer the residual nerves to these muscles. Cutaneous nerves innervating residual limb skin will also be transferred for anastomosis to the residual hand nerves to provide targeted sensory feedback. 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 transfer muscle sites to control a myoelectric hand, powered elbow and possibly a powered wrist (all simultaneously in a natural fashion). Performance testing will be repeated with the experimental myoelectric system for comparison to conventional measures.