Evaluation of Hindpaw Position in Rats during Chronic Constriction Injury (CCI) Produced with Different Suture Materials

Bennett and Xie (1988) described an experimental peripheral neuropathy that is produced by loosely ligating a rat's left sciatic nerve with chromic gut suture. Four ligations, which are tied tightly enough to constrict the nerve and retard epineurial blood flow, produce a chronic constriction injury (CCI). Maves et al. (1993) reported that if the ligations are tied more loosely (i.e., no retardation of blood flow) than those that produce the CCI, rats exhibit postural changes only when the ligations are of chromic gut. We decided to evaluate effects of different suture materials on the abnormalities in paw position associated with the CCI (Attal et al., 1990). Five groups of rats were included in this study. In three of the groups, the CCI was produced with chromic gut, plain gut, or polyglactin (Vicryl) suture. Rats in the fourth group served as sham injury control animals, and rats in the fifth group served as unoperated control animals. Our results indicate that the position in which the rats held the affected hindpaw varied significantly among treatment groups. Rats whose CCI was induced with chromic gut suture spent more time with the hindpaw in an abnormal position than rats in the other treatment groups. And as compared to rats in the unoperated control group, rats whose CCI was induced with either plain gut or polyglactin suture also spent more time with the hindpaw in an abnormal position. Though these different suture materials produced similar degrees of nerve constriction, the effects on paw position were greater with chromic gut suture. These results suggest that chromic gut suture, when used to produce the CCI, may have more than just a constrictive effect on the sciatic nerve. However, since all suture materials produced changes in paw position, constriction is likely to play an important role in the development of abnormalities in paw position observed in rats with the CCI.