Motor functional and morphological findings following end-to-side neurorrhaphy in the rat model

Nerve repair cannot always be achieved by the conventional end-to-end techn ique. This study evaluated the functional recovery of nerves repaired with end-to-side neurorrhaphy in a rat model. The right peroneal nerves of 80 fe male rats were transected and divided into four groups. In group A, the ner ve ends were separated and remained unrepaired; in group B, the distal pero neal ends were directly sutured to the epineurium of the tibial nerves in e nd-to-side fashion; in group C, the distal ends were sutured through an epi neurial window at the repair site in end-to-side fashion; and in group D, t he nerve ends were reconnected by the traditional end-to-end technique. Eva luation included gait analysis by calculation of a peroneal functional inde x, measurement of contractile function of the extensor digitorum longus mus cle, wet weight of the extensor digitorum longus, and histological examinat ion. The findings of this study suggested the following: (a) end-to-side ne urorrhaphy allows effective motor functional recovery, demonstrated by earl ier improvement of the peroneal functional index, stronger muscle contracti le function, greater muscle weight, and higher density of regenerated axons compared with unrepaired nerves; (b) removal of the epineurium of the dono r nerve at the nerve coaptation site increases the effectiveness of end-to- side neurorrhaphy, but the epineurium appears to be a partial barrier to ax onal regeneration; (c) removal of the epineurium does not affect the struct ure and function of the donor nerve; and (d) end-to-end repair achieved the best functional recovery among the four groups; therefore, end-to-side rep air should be considered as a potential alternative only when no proximal n erve is available.