Performance of Two Different Targeted Muscle Reinnervation Approaches for Improving Myoelectric Prosthetic Control

Targeted Muscle Reinnervation (TMR) is a surgical approach that can produce a neural-machine interface to provide additional electromyography (EMG) signals in intuitive control of myoelectric prostheses for high-level limb amputees. Clinically, TMR interface can be built by two types of surgical protocols. The first surgical protocol is to transfer a residual nerve to a denervated targeted muscle using a nerve-to-muscle suture and another is to anastomose a residual nerve to a targeted nerve via a nerve-to-nerve suture. Currently, it still remains unknown which surgical protocol would be more suitable for their clinical applications. In this study, a comparative investigation of the two TMR protocols was conducted by using animals and their performance in reconstructing EMG signals was evaluated. For nerve-to-muscle animal model, the proximal end of ulnar nerve was implanted onto denervated biceps brachii muscle and for nerve-to-nerve model, the proximal end of ulnar nerve was anastomosed to the distal end of musculocutaneous nerve. Post-surgery EMG signals were collected from all the TMR animals. Our results showed that the amplitudes of EMG signals gradually increased for the animals in the two TMR protocols over time, with an obvious difference between nerve-to-muscle and nerve-to-nerve animals. The signal-to-noise ratio and the centroid frequency of EMG signals in nerve-to-muscle animals were notably higher than those in nerve-to-muscle animals. These superior characteristics of the postoperative EMG signals demonstrated that nerve-to-nerve surgical protocol would be better than nerve-to-muscle in reconstructing EMG signals. The findings of this animal study suggest that both the TMR surgical protocols could be useful in providing additional EMG signals for myoelectric control, while the nerve-to-nerve suture would outperform the nerve-to-muscle suture in the quality and the appearance of the reconstructed extra EMG signals.