Background. The purpose of this experiment was to develop a peripheral nerve interface using cultured myoblasts within a scaffold to provide a biologically stable interface while providing signal amplification for neuroprosthetic control and preventing neuroma formation. Methods. A Regenerative Peripheral Nerve Interface (RPNI) composed of a scaffold and cultured myoblasts was implanted on the end of a divided peroneal nerve in rats (n = 25). The scaffold material consisted of either silicone mesh, acellular muscle, or acellular muscle with chemically polymerized poly(3,4-ethylenedioxythiophene) conductive polymer. Average implantation time was 93 days. Electrophysiological tests were performed at endpoint to determine RPNI viability and ability to transduce neural signals. Tissue samples were examined using both light microscopy and immunohistochemistry. Results. All implanted RPNIs, regardless of scaffold type, remained viable and displayed robust vascularity. Electromyographic activity and stimulated compound muscle action potentials were successfully recorded from all RPNIs. Physiologic efferent motor action potentials were detected from RPNIs in response to sensory foot stimulation. Histology and transmission electron microscopy revealed mature muscle fibers, axonal regeneration without neuroma formation, neovascularization, and synaptogenesis. Desmin staining confirmed the preservation and maturation of myoblasts within the RPNIs. Conclusions. RPNI demonstrates significant myoblast maturation, innervation, and vascularization without neuroma formation.

Chronic lateral ankle instability can occur in a subset of patients following ankle inversion sprains. Operative treatment to restore stability in the ankle and hindfoot and to prevent further degenerative changes may be indicated in cases in which nonoperative treatment has failed. Anatomical direct repair with use of native ligament remnants with or without reinforcement of the inferior retinaculum is the so-called gold standard operative strategy for the treatment of lateral ankle instability. The procedure has shown promising short and long-term outcomes. Candidates for the procedure have ligament remnants of sufficient quality that are amendable to direct repair. Anatomical reconstruction with use of autograft or allograft is reserved for patients with insufficient ligament remnants to fashion a direct repair, failed previous lateral ankle repair, high body mass index, or generalized ligamentous laxity. A wide variety of autografts have been described, each with potential advantages and disadvantages. These procedures can provide good-to-excellent short-term outcomes. However, there is no available information on their long-term clinical results. Non-anatomical lateral ligament reconstruction typically involves the use of the adjacent peroneal brevis tendon and has been applied in cases in which only poor-quality ligament remains. The procedure can provide good to excellent short-term outcomes, although reported long-term outcomes have differed among studies. The particular tendon used for the graft should be carefully considered given the potential alterations in the kinematics of the ankle and hindfoot. Arthroscopic ligament repair is becoming increasingly popular as it is minimally invasive. This procedure is restricted to patients who have good-quality ligament remnants. Good-to-excellent clinical outcomes have been reported after short and long-term follow-up, although a relatively high rate of complications-including nerve damage-has been reported following the procedure and therefore warrants further investigation before widespread adoption can be advocated.

Therapeutic, III.