Early muscle reinnervation by means of end-to-side neurorrhaphy in an experimental model

Aim: The aim of the study was to provide early muscular reinnervation to avoid muscle atrophy and functional loss in an experimental model. Methods: Fifty rats were divided into five groups. In group 0 (control group) only nerve dissection was performed. Total peroneal nerve section was performed in the remaining groups. Immediate end-to-end neurorrhaphy (EEN) was made in group 1. In group 2, an end-to-side neurorrhaphy (ESN) was performed from the tibial nerve to the peroneal nerve. In group 3, a direct EEN, plus an ESN, were used as a nerve graft as a bridge from the donor nerve (tibial); all nerve coaptations were performed through an epineural window. In group 4, only a neurotomy was made without any type of reconstruction. Results: Neural diameters were similar in groups 0, 1, and 3 (38 ± 1 mm, 31 ± 6 mm, 32 ± 3 mm). Neural fibers in group 3 had an 18% increase in the number of axons (P < 0.001) when compared to group 0. Group 2 (28 ± 1 mm) and group 4 (19 ± 3 mm) had diminished diameters with a lower index of muscle regeneration. Animals in group 4 presented with “clawed” lower extremities and had difficulty with ambulation. Neural graft diameters was similar in groups 2 and 3 (33 ± 4 mm, 31 ± 3 mm), but axon density was significantly higher in group 3 (53 ± 6 mm, 39 ± 8 mm) (P < 0.001). Axon density was 36% higher when the combination of EEN and ESN with a neural graft through an epineural window was performed. Conclusion: This study revealed that the combination of EEN and ESN repairs with the addition of a neural graft provides a lower index of muscle fiber destruction, and can be a reliable method for reconstruction in high neural injuries. ABSTRACT