Carrie Ann Kubiak1, Shelby Svientek2, Amir Dehdashtian3, Nathan Lawera3, Vidhya Nadarajan3, Jarred Bratley3, Theodore Kung3, Paul S Cederna4, Stephen William Peter Kemp5. 1. Section of Plastic Surgery , University of Michigan Hospital Department of Surgery, 2130 Taubman Center, 1500 E. Medical Center Drive, Ann Arbor, Ann Arbor, Michigan, 48109-5000, UNITED STATES. 2. University of Michigan, 1150 W Medical Center Drive, Ann Arbor, 48109-1382, UNITED STATES. 3. University of Michigan, 1150 W Medical Center Drive, Ann Arbor, Michigan, 48109-1382, UNITED STATES. 4. Department of Surgery, University of Michigan, Section of Plastic Surgery, Ann Arbor, 48109, UNITED STATES. 5. Surgery, University of Michigan, 1150 W Medical Center Drive, Ann Arbor, Michigan, 48109-1382, UNITED STATES.
Abstract
OBJECTIVE: Exoskeleton devices are a promising modality for restoration of extremity function in individuals with functional muscle weakness. However, no consistent or reliable way to effectively record efferent motor action potentials from intact peripheral nerves to control device movement exists. Here, we have developed the Muscle Cuff Regenerative Peripheral Nerve Interface (MC-RPNI), which consists of a free skeletal muscle graft wrapped circumferentially around an intact peripheral nerve. Our objective was to characterize the signaling capabilities and viability of the MC-RPNI. APPROACH: Thirty-seven rats were randomly assigned to one of five groups. For MC-RPNI animals, contralateral extensor digitorum longus (EDL) muscle was harvested and trimmed to 8 mm (Group A) or 13 mm (Group B) in length, and wrapped circumferentially around the intact ipsilateral common peroneal (CP) nerve. One 8 mm (Group C) and 13 mm (Group D) length group had an epineurial window created in the CP nerve immediately preceding MC-RPNI creation. Group E consisted of sham surgery. Additionally, isometric force analyses was performed on the distal CP-innervated EDL. MAIN RESULTS: Compound muscle action potentials (CMAPs) were recorded from MC-RPNIs and ranged from 3.67±0.58 to 6.04±1.01 mV, providing efferent motor action potential amplification of 10-20 times that of a normal physiologic nerve action potential. Maximum tetanic isometric force (Fo) testing produced values similar to controls, demonstrating that MC-RPNIs did not adversely impact distally-innervated EDL function. Comparison between MC-RPNI sub-groups did not reveal any statistical differences in signaling capabilities. SIGNIFICANCE: MC-RPNIs have the capability to provide efferent motor action potential amplification from intact nerves without adversely impacting distal muscle function. Neither the size of the muscle graft nor the presence of an epineurial window in the nerve had any significant impact. These results support the potential for the MC-RPNI to serve as a biologic nerve interface to control advanced exoskeleton devices.
OBJECTIVE: Exoskeleton devices are a promising modality for restoration of extremity function in individuals with functional muscle weakness. However, no consistent or reliable way to effectively record efferent motor action potentials from intact peripheral nerves to control device movement exists. Here, we have developed the Muscle Cuff Regenerative Peripheral Nerve Interface (MC-RPNI), which consists of a free skeletal muscle graft wrapped circumferentially around an intact peripheral nerve. Our objective was to characterize the signaling capabilities and viability of the MC-RPNI. APPROACH: Thirty-seven rats were randomly assigned to one of five groups. For MC-RPNI animals, contralateral extensor digitorum longus (EDL) muscle was harvested and trimmed to 8 mm (Group A) or 13 mm (Group B) in length, and wrapped circumferentially around the intact ipsilateral common peroneal (CP) nerve. One 8 mm (Group C) and 13 mm (Group D) length group had an epineurial window created in the CP nerve immediately preceding MC-RPNI creation. Group E consisted of sham surgery. Additionally, isometric force analyses was performed on the distal CP-innervated EDL. MAIN RESULTS: Compound muscle action potentials (CMAPs) were recorded from MC-RPNIs and ranged from 3.67±0.58 to 6.04±1.01 mV, providing efferent motor action potential amplification of 10-20 times that of a normal physiologic nerve action potential. Maximum tetanic isometric force (Fo) testing produced values similar to controls, demonstrating that MC-RPNIs did not adversely impact distally-innervated EDL function. Comparison between MC-RPNI sub-groups did not reveal any statistical differences in signaling capabilities. SIGNIFICANCE: MC-RPNIs have the capability to provide efferent motor action potential amplification from intact nerves without adversely impacting distal muscle function. Neither the size of the muscle graft nor the presence of an epineurial window in the nerve had any significant impact. These results support the potential for the MC-RPNI to serve as a biologic nerve interface to control advanced exoskeleton devices.