Targeted Muscle Reinnervation for Intuitive Prosthetic Control

The convergence of medical and technological advances has led to a substantial expansion of therapeutic approaches for patients with limb amputations. Targeted muscle reinnervation (TMR) is one of the strategies to improve control of bionic arms and has been applied for more than two decades. Through surgical rewiring of the nerves responsible for hand functions to a new muscle target, a neuromuscular interface of the lost extremity is created, enabling improved prosthetic control. Neural information that would otherwise be lost through transected peripheral nerves is thus reestablished and can be accessed via electromyographic (EMG) signal recordings to allow intuitive control of myoelectric prostheses. This is of particular importance in high upper-limb amputations, as muscles available for signal acquisition are limited in these cases. While utilizing trunk muscles is a viable option, it is unintuitive for controlling hand function. TMR not only increases the number of available signal sites but also enables prosthetic movements driven by coherent central motor intent. Coupled with advances in algorithm-based prosthetic control and implantable electrodes, the number of usable signals and corresponding degrees of freedom is further increased. Most recent approaches aim at utilizing high-density EMG to capture multiple signals from individual nerve-muscle interfaces to exploit the full potential of TMR. This review endeavors to provide a comprehensive overview of TMR for prosthetic control, covering patient selection, surgical technique and postoperative rehabilitation. Furthermore, the neurophysiological principles underlying TMR, current state-of-the-art technologies, and emerging prospects that may reshape the future of human-machine integration are discussed.