Biological performance of a degradable poly(lactic acid-epsilon-caprolactone) nerve guide: influence of tube dimensions

One of the ways to reconstruct a nerve defect is to use a biodegradable nerve guide. The aim of this study was to establish a nerve guide constructed of an amorphous copolymer of lactic acid-caprolactone. A pilot study was set up to elucidate the effect of the tube dimensions on nerve regeneration. Four types of nerve guides, with internal diameters ranging from 1.12-1.23 mm and wall thicknesses ranging from 0.34-0.68, were tested for this purpose. We evaluated the biodegradation, foreign body reaction and nerve regeneration by light microscopy, after three different implantation times (1, 2, and 3 months). After 2 months, we observed that all types of nerve guides had changed from a transparent to an opaque and swollen state, and that they had lost their strength. The foreign body reaction was characterized by the presence of giant cells and fibroblasts surrounding the degrading nerve guide. From this pilot study, we conclude that nerve guide type 1, with an internal diameter of 1.23 mm and a wall thickness of 0.34 mm, can ensure nerve regeneration in the case of a 1-cm gap in the sciatic nerve of the rat. Nerve guides types 3 and 4, with relatively small lumens, show nerve compression due to a more pronounced swelling of the degrading tube.