Functional recovery following neurorrhaphy of the rat sciatic nerve by epineurial repair compared with tubulization

Recovery of motor function is often poor following transection injuries to peripheral nerves. The purpose of this study was to measure and compare functional recovery of the sciatic nerve in the rat following transection and neurorrhaphy with the use of a nerve guide tube and with traditional end-to-end epineurial repair. Muscle recovery was also evaluated following a crush injury, a model of an axonotmetic lesion. Recovery was assessed at 8, 16, and 32 weeks after injury by measuring the isometric contractile properties of the soleus muscle and at 8 and 16 weeks by measuring the conduction properties of the sciatic nerve. The mean conduction velocity of the sciatic nerve in the crush group and both transection groups was significantly slower than that of controls at both 8 and 16 weeks. Following a transection injury, the soleus became a significantly faster muscle as measured by time to peak twitch tension. By 32 weeks, the maximum isometric tension of the soleus muscle recovered to 90% that of the control group following a crush injury and to less than 70% following a transection injury and repair. Recovery was better in the epineurial repair group than in the tube repair group at 8 weeks, but no difference was found between the groups at 16 or 32 weeks. These results demonstrate that nerve guide tubes are a potential alternative to epineurial repair. The poor motor recovery following repair of transection injuries may be related to poor specificity of reinnervation.