Protecting the Nerve Coaptation: Connector-Assisted Nerve Repair in Complex Injuries.

Purpose: This study evaluated differences in outcomes of peripheral nerve repair using connector-assisted repair (CAR) or direct repair (DR) in an injured soft tissue bed. Methods: The sciatic nerve of the right leg in 20 male Lewis rats was exposed and transected. We simulated a traumatized wound bed by cauterizing the underlying muscle bed with a bipolar coagulator. Nerves were repaired with either DR or CAR using porcine small intestine submucosa conduits. At 6 weeks, adhesions were assessed semiquantitiatively, and the gastrocnemius wet muscle weight of each hind limb was recorded to evaluate muscle atrophy. Histology of the nerve was evaluated immediately distal to the nerve repair site. Data were analyzed for differences between repair methods. Results: The DR group had a considerably higher area of foamy phagocytes and CD68-stained macrophages than that of the CAR group. There were considerably more blood vessels and axons in the CAR group than in the DR group. There were no differences between DR and CAR with respect to gastrocnemius muscle wet weight, extraneural adhesions, or intraneural collagen-to-cell ratio. Conclusions: There was less area occupied by macrophages and foamy phagocytes in the CAR group, which was indicative of lower inflammatory response and resolving Wallerian degeneration. The CAR group also had more blood vessels and axons compared to that of the DR group, indicating more robust nerve regeneration. Gastrocnemius muscle weight between groups was similar, indicating that nerve regeneration was incomplete in both groups at the 6-week timepoint. These results highlight the potential benefits of CAR in protecting the nerve during the healing process. Clinical relevance: This in vivo study evaluates histological changes in peripheral nerves during regeneration following transection with either CAR or DR.