Is End‐to‐Side Neurorrhaphy Effective? A Study of Axonal Sprouting Stimulated from Intact Nerves

ABSTRACT

The purpose of this study was to determine if axonal sprouting across an end-to-side coaptation could be stimulated and if so, to identify the source of the regenerating axons. Mechanical trauma, the method used to stimulate axonal sprouting, was compared to a control group with coaptation only and an additional non-grafted control group. After a 20-week recovery period, electrical stimulation revealed that the target muscles had been reinnervated in all groups except the non-grafted control group. Axonal counting demonstrated a significant increase for the mechanical trauma group compared to the control group with coaptation only [ratio of the density of axons/μm² of the experimental to the contralateral control side: 2.78 ± 0.11 vs. 0.96 ± 0.15, respectively, p < 0.002]. Tibialis anterior muscle weights were significantly increased for both groups vs. the non-grafted control group [ratio of experimental to the contralateral control side: coaptation-only control, 0.539 ± 0.024; mechanical trauma, 0.538 ± 0.036 vs. non-grafted control, 0.220 ± 0.003, p < 0.002]. Of importance, this study provides evidence that the intact tibial nerve functions as a bridge for regenerating axons derived from the proximal peroneal stump. This suggests an alternative explanation to successful end-to-side axonal sprouting, and questions the clinical utility of end-to-side coaptation.