Supercharge Nerve Transfer to Enhance Motor Recovery: A Laboratory Study

Purpose To investigate the ability of a supercharge end-to-side (SETS) nerve transfer to augment the effect of regenerating native axons in an incomplete rodent sciatic nerve injury model. Methods Fifty-four Lewis rats were randomized to 3 groups. The first group was an incomplete recovery model (IRM) of the tibial nerve complemented with an SETS transfer from the peroneal nerve (SETS-IRM). The IRM consisted of tibial nerve transection and immediate repair using a 10-mm fresh tibial isograft to provide some, but incomplete, nerve recovery. The 2 control groups were IRM alone and SETS alone. Nerve histomorphometry, electron microscopy, retrograde labeling, and muscle force testing were performed. Results Histomorphometry of the distal tibial nerve showed significantly increased myelinated axonal counts in the SETS-IRM group compared with the IRM and SETS groups at 5 and 8 weeks. Retrograde labeling at 8 weeks confirmed increased motoneuron counts in the SETS-IRM group. Functional recovery at 8 weeks showed a significant increase in muscle-specific force in the SETS-IRM group compared with the IRM group. Conclusions An SETS transfer enhanced recovery from an incomplete nerve injury as determined by histomorphometry, motoneuron labeling within the spinal cord, and muscle force measurements. Clinical relevance An SETS distal nerve transfer may be useful in nerve injuries with incomplete regeneration such as proximal Sunderland II- or III-degree injuries, in which long regeneration distance yields prolonged time to muscle reinnervation and suboptimal functional recovery. (J Hand Surg 2013;38A:466-477. Copyright (C) 2013 by the American Society for Surgery of the Hand. All rights reserved.)