Reinnervated Split-Muscle Technique for Creating Additional Myoelectric Sites in an Animal Model

Abstract

Background: This study proposes a novel reinnervated split-muscle operation to create additional myoelectric sites as sources of command signals of myoelectric prostheses for enhanced dexterous hand-to-wrist motions. The aim of this study was to investigate the postprocedure electromyographic properties of the muscles as distinct myoelectric sites in a rat model. Methods: The reinnervated split-muscle group (n = 6) had the gastrocnemius muscle separated along its longitudinal axis and nerves transferred to each new muscle (peroneal nerve to lateral muscle head and tibial to medial one); the non-split-muscle group (n = 6) only had nerve transfers with its muscle intact. Functional testing was conducted after 10 weeks. The main parameter is the difference in mean electromyographic amplitude between the new muscles, with greater values indicating better separability. Results: After the reinnervated split-muscle procedure, there is a significant increase of the average ratio between two muscles compared with the control group, from 0.44 (range, 0.02 to 0.86) to 0.77 (range, 0.35 to 0.98) (p = 0.011). In addition, compared with the non-split muscle group, nerve transfer in the split-muscle group is more successful in reaching its intended target muscle. Conclusion: A reinnervated split-muscle procedure could be beneficial for acquiring a more precise and discrete command signal in upper limb amputees, thus enabling the creation of more dexterous prosthetic arm.