Is end-to-side neurorrhaphy effective? A study of axonal sprouting stimulated from intact nerves

The purpose of this study was to determine if axonal sprouting across an en d-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, e lectrical stimulation revealed that the target muscles had been reinnervate d in all groups except the non-grafted control group. Axonal counting demon strated a significant increase for the mechanical trauma group compared to the control group with coaptation only [ratio of the density of axons/mu m( 2) 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 gr oup [ratio of experimental to the contralateral control side: coaptation-on ly control, 0.539 +/- 0.024; mechanical trauma, 0.538 +/- 0.076 vs. nongraf ted control, 0.220 +/- 0.003, p < 0.002]. Of importance, this study provide s evidence that the intact tibial nerve functions as a bridge for regenerat ing axons derived from the proximal peroneal stump. This suggests an altern ative explanation to successful end-to-side axonal sprouting, and questions the clinical utility of end-to-side coaptation.