Application of Targeted Reinnervation for People With Transradial Amputation

The purpose of this study is to improve prosthesis control for transradial amputees with combining targeted muscle reinnervation surgery (TMR) and pattern recognition control.

Phase 1: Transradial amputees will be asked to come to the Rehabilitation Institute of Chicago, Walter Reed National Military Medical Center or the San Antonio Military Medical Center for initial fitting with a prosthetist for a multifunctional hand system or multifunctional hand and wrist system. The prosthesis system will consist of a custom-made socket and commercially available components. The first visit (up to five days)s involves casting, creating and fitting of a socket that will be used for the study. During the initial and subsequent visits, the subject will be asked asked to practice various control methods using a virtual reality system. EMG data and virtual "games" will be used to practice the control and will provide quantitative data that can be used to assess the various control methods mathematically, without the prosthesis. Once they receive a socket, they will complete 1-3 days of training to learn how to control the prosthesis with either conventional or pattern recognition control. The prosthetic training days may occur concurrently with the fitting appointment or it may require a separate visit. The subject will return home for the initial 8 week home use trial. They will be asked to use the prosthesis for an average of 2 hours per day across the 8 week home trial period. They will keep a home log of prosthesis use and check in weekly with a therapist to discuss usage and prosthesis performance. They may also be provided with a laptop computer with a camera for Skyping. The laptop can be connected to the prosthesis, and the screen can be viewed remotely. The research team can then continue with remote follow up with more training and problem solving as needed. Directly following the 8 week home trial period, usage data from the prosthesis will be downloaded. The subject will complete 1-3 days of outcomes testing with a therapist. A series of tests will be performed and data recorded of your performance. The subject will then repeat the 1-3 days of training, 8 week home trial period, and 1-3 days of outcomes testing with either the other type of control (i.e. conventional or pattern recognition). Phase 2: The subject will return to one of the three centers for Targeted Muscle Reinnervation (TMR) surgery. The surgery is an outpatient procedure that will be performed under general anesthesia, consistent with current standard of care. The surgery will involve the transfer of the median nerve to the flexor digitorum superficialis (DFS) muscle and the ulnar nerve will be transferred to the flexor carpi ulnaris (FCU) muscle. Both transfers can be done with a single incision. Alternative target muscles (e.g. the brachioradialis muscle) can be used if trauma interferes with use of the DFS and/or FCU. Some post-operative pain is expected and the subject will be given a prescription for pain medication if needed. Two weeks after the surgery the subject will be asked to start doing exercises to help with muscle recovery. They will return to using the prosthesis from Phase 1 with either conventional or pattern recognition control for 6 months after surgery. Socket adjustments will be made if needed. If they return to using pattern recognition control, their usage and performance data will be tracked during this 6 month period. The subject may be provided with a laptop computer and asked to perform a series of virtual tests. They will receive additional training on how to complete these tests. If the subject returns to using conventional control, they will not be asked to complete the additional tests, nor will the usage or performance data be tracked. Six months after surgery, when reinnervation of the target muscles has been completed, the subject will return to using the prosthesis with pattern recognition control. They will be asked to return to one of the three centers if socket adjustments or a replacement socket is needed. The subject will receive 1-3 days of pattern recognition control training, only this time special attention will be paid to utilizing EMG from target muscles for improved function. Preliminary testing will be done to ensure that they can adequately use the prosthesis. The subject will then take the prosthesis home for a third 8-week home-use trial. The subject will be asked to log daily use of the device, note any issues, and follow up weekly with a therapist. After this home-use trial, the same 1-3 days of comprehensive outcomes testing will be completed and usage data from their prostheses will be downloaded. Finally, the subject will continue using the prostheses at home for an additional 3-4 months. No usage requirements will be given during this time. At the end of this 3-4 month period (approximately 12 months after surgery), they will have a final round of 1-3 days of testing with the complete toolbox and data from the prosthesis will be downloaded. The days of prosthesis training and testing may take place at the Rehabilitation Institute of Chicago, Walter Reed National Military Medical Center, or the San Antonio Military Medical Center or near your home. Study coordinators will determine the best location.