Characteristics of the sciatic nerve injuries inflicted by high-velocity triangle fragments in swine / 中华创伤杂志

ABSTRACT

Objective To study the characteristics of the sciatic nerve injuries inflicted by highvelocity triangle fragments in swine.Methods According to the injury position,14 swines weighing (34.29±5.2)kg were divided into two groups.All swines were shot by 0.37 g triangle fragments at (773.1±12.4)m/s aimed at the midpoint of the lateral body surface projection of the right sciatic nerve in Group A(n=7)and at 2 cm aside from sciatic nerve in Group B(n=7).The entrance,exit and length of wound tract,distance between nerve and wound tract were detected,and the pathology of sciatic nerve and wound tract at 48 hours after injury were observed under light microscope and electron microscope.Results The course of the fragments was deviated to different extent.Six sciatic nerves were in primary wound tract,four of which were lacerated and ruptured at different degrees.The light microscope showed pathological changes including severe hemorrhage and edema,leukocytic infiltration,neurotmesis,axonotmesis and light myelin coloration;while electron microscope showed severe degeneration of myelin sheath and neuraxon distortion.Six nerves(one in Group A and five in Group B)were in the concussion zone,with the distance between sciatic nerve and primary wound tract for(2.07±0.45)cm.Hyporrhea and hyperemia under perilemma and perineurium,partial nerve fiber disrupt and axonotmesis were observed by light microscope and partly myelin sheath delamination by electron microscope.Two nerves (one in Group A and another in Group B)were in the contusion zone,with moderate pathological changes.Conclusions The track of high velocity triangle fragments is unstable in the tissues.High disrupt rate,severe and wide extent lesion,early Wallerian degeneration are the main characteristics of direct injuries of swine's sciatic nerves.Indirect injuries can induce pathologic changes too,for which the lesion severity is related to the distance between nerves and primary wound tract.