A comparative study on primary and secondary nerve repair.

The sciatic nerve of rats was severed, and in the first group of rats the nerve repair was made immediately; in the second group, 1 month after severance; and in the third group, 2 months after severance. These rats were allowed to survive for 1, 2, 3, 5, and 7 months after nerve repair. At the seventh month after primary nerve repair, the average weight of the reinnervated anterior tibial muscle was 67 percent of that of the control muscle, and the cytochemical structure of the muscle fibers and subneural apparatuses was almost identical to those of the control. However, in the secondary nerve repair groups with neurorrhaphy 1 and 2 months after nerve severance, the average muscle weight was 50 and 60 percent, respectively, of that of the control. The cytochemical structure of both the muscle fibers and subneural apparatuses was not so mature as that of primary nerve repair. Furthermore, in rats with primary nerve repair, the size of muscle fibers was larger than that of rats with secondary nerve repair. The results observed in this experimental study strongly suggest the superiority of primary nerve repair over secondary nerve repair.