Relationship of intraneural damage in the rat sciatic nerve to the mechanism of injury.

The degree of nerve injury is difficult to determine and varies according to the mechanism of injury. Experimental nerve avulsion, cut, crush, and saw injuries were produced in male Sprague-Dawley rats. The extent of nerve damage was assessed histologically and by intraoperative observations on days 1, 8, and 21 post-injury. Nerve avulsions produced the most severe injury, followed by saw, crush, and cut mechanisms of injury. The intraoperative observations on day 1 were not predictors of the degree of injury at day 21. Avulsion injuries are most suitably treated secondarily by a nerve reconstruction technique, not by a primary repair.