Effects of delayed nerve repair on regeneration of rat sciatic nerve.

The optimal time for nerve suture in transected rat sciatic nerve was investigated. The sciatic nerve on both side nerves were transected and repaired by an epineurial suture technique 0-28 days after nerve transection. The regeneration distance was measured by the sensory pinch reflex test 2-6 days after nerve repair. The initial delay period and the regeneration rate were calculated by using a new mathematical model. One day delayed repair was sufficient to reduce the initial delay period and the largest reduction on the initial delay period was observed in the three day delayed repair group. The initial delay period was reduced to 0.87 days as compared to 2.31 days for nerves repaired immediately (controls). The seven day and ten day delayed repair had similar effects but they also showed a decrease of the regeneration rate. The regeneration rate was not affected except for these two time points. The results suggest that the repair delay period can influence the initial delay as well as the regeneration rate. In our model an optimal effect was achieved on both these measures with a one or three day delay between transection and repair.