Effects of subepineural hyaluronic acid injection on nerve recovery in a rat sciatic nerve defect model

BACKGROUND: Maintenance of epineural integrity is very important for nerve healing. Reports on the use of substances considered to have positive effects on nerve healing in experimental nerve defect models are increasing. The present study assessed the effects of sub-epineural hyaluronic acid injection in a rat sciatic nerve defect model that was created while maintaining epineural integrity. METHODS: The study included 40 Sprague Dawley rats. The rats were randomly divided into a control group and three experimental groups (10 rats in each group). In the control group, the sciatic nerve was dissected and no additional surgery was performed. In experimental group 1, the sciatic nerve was transected in the middle, and then, primary repair was performed. In experimental group 2, a 1-cm defect was created while preserving the epineurium, and then, the defect was repaired with end-to-end suturing of the preserved epineurium. In experimental group 3, the surgical procedure for experimental group 2 was performed, and then, sub-epineural hyaluronic acid injection was carried out. Functional and histological evaluations were performed. RESULTS: On functional evaluation, there was no statistically significant difference among the groups during the 12-week follow-up period. On histological evaluation, nerve recovery was poorer in experimental group 2 than in experimental groups 1 and 3 (p<0.05). CONCLUSION: Although the functional analysis did not reveal any significant results, the histological findings suggest that hyaluronic acid increases the regeneration capacity of axons through its anti-fibrotic and anti-inflammatory effects.