Targeted Muscle Reinnervation (TMR) and Other Considerations in Upper Extremity Amputation

Targeted muscle reinnervation (TMR) is a procedure in which amputated nerves are transferred to motor branches of functionally expendable muscles, which can then serve as "biological amplifiers" of neurologic information. It is a technique that was developed with the primary intent of improving myoelectric prosthesis control in high level upper extremity amputees. Over time, TMR has been shown to confer significant benefits in terms of both residual and phantom limb pain and as such has become a powerful tool in neuroma management in amputees and non-amputees. This review first discusses general principles of amputation management in the upper extremity, including the different types of prosthetics that are available for these patients. The history, rationale, and evolution of TMR will then be outlined, followed by several relevant surgical principles. Finally, the current evidence for and against TMR will be reviewed. Robust data on the functional benefits are still needed, and future studies will continue to clarify its role in both upper and lower extremity amputees.