Complete regenerative peripheral nerve interfaces, fatigue and recovery

Modern technology has taken great strides to restore motion to amputees with prostheses. A key limitation in many cases is lack of a reliable controlling interface to the prosthetic devices. To address this issue, our lab has developed the Regenerative Peripheral Nerve Interface (RPNI). RPNIs transduce signals between residual peripheral nerves, muscle grafts, and prosthetic devices. Prior to this study, RPNI´s signal production was primarily evaluated during single evoked maximal action potential. The purpose of this study was to characterize RPNI function during and after repeated submaximal use. RPNIs (n=5) were constructed in a rat model by transferring the EDL muscle from the lower hind limb to the hip region and implanting the transected peroneal nerve into the muscle. Control EDL muscles (n=8) were left in the native location. The muscles were evaluated at least five months postoperatively in terms of maximum evoked compound muscle action potentials, force production, force production during repeated use, and post-fatigue force production. There was a strong correlation between maximum compound muscle action potential amplitude and maximum contractile force (r=0.83 p <; 0.01); thus, force was an indication of signaling. RPNI and Control muscles both fatigued as exponential regressions. Percent post fatigue force production did not differ significantly between the groups, with Controls recovering to 85% of initial maximum force and RPNIs recovering to 60%. RPNIs produce and recover signals in the same relative manner as Controls indicating RPNIs are prime candidates as controlling interfaces for myoelectric prosthetic devices.