Experimental Protocol for Study and Evaluation of Post-Surgical Perineural Scar

Introduction: The perineural fibrotic adhesion is one of the major complications of surgery of the peripheral nervous system. Many authors tested biocompatible antiaderential devices on animal models, but the methods used to induce scar tissue are different and not standardized. This work intends to compare different protocols to identify the best to induce perineural fibrosis and standardize a simple and reproducible protocol for the study of perineural scar after surgery.

Methodology and Material: 25 adult mice were used. We tested two methods of injury: the first one is burn perineural muscular bed with diathermo, the second one is scratch the nerve surface with cotton swab. The animals were sacrificed after 3 weeks. In each group we investigated the fibrotic reaction measuring the maximum force required to detach the nerve from muscular bed by means a tool specifically created. To this was associated histological analysis with collagen specific stain called Sirius red.

Results: Both methods produce fibrotic reaction. In burned group maximal adhesion force was 62 g, 47 g for scratching group, 37 g for control group. The statistical analysis shows a significant difference between the group of burn and the control group. The histological analysis showed perineural scar tissue in both groups, but with a different distribution and morphology.

Conclusions: The best method to induce a perineural fibrotic reaction is burn muscular bed. The method we have developed is effective and easy to perform and may be therefore a reproducible model for the study of the effectiveness of anti-adhesion devices. Our study also shows that the experimental evaluation of perineural adhesions should not be limited only to the histological analysis, but must be associated with biomechanical study to avoid underestimation of adherence’s entity.