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Physical Characteristics of Nerve-guide Can Correlate with the Effectiveness of Regeneration
Antonio Merolli, MD; Salvatore Marceddu; Luigi Mingarelli; Francesco Catalano
The Catholic University, Rome, Italy
Introduction: There are several degradable tubular nerve-guides (or conduits) in clinical use. Stitch suture is still the most recommended method to hold them in place, despite the well-known adverse inflammatory response elicited by stitches. In 2006 we proposed a new concept of nerve-guide, termed "NeuroBox", which is flat, double-halved, not-degradable and rigid, and allows the use of cyanoacrylic glues instead of stitches. The physical characteristics of the NeuroBox guide are quite different from traditional cylindrical guides and Authors suspected that they may improve the effectiveness of nerve regeneration.
EXPERIMENTAL METHODS: We compared the histomorphology of the regenerated nerve, between poly-methyl-metacrylate (PMMA) NeuroBox shaped guides (NBX) and traditional treated-collagen cylindrical shaped guides (TCC). Analysis was performed by visible light microscopy (VLM) and transmission electron microscopy (TEM). The experimental model was the gap-lesion of the sciatic nerve in the male Wistar rat (10 samples of NBX and 5 samples of TCC). Intact contralateral nerves were harvested as control.
RESULTS AND DISCUSSION: Macroscopic nerve regeneration occurred in 10/10 of the NBX guides and in 4/5 TCC guides: however this difference was not considered significative, due to the small dimension of the samples. When examined under VLM, the regenerated nerve inside the NBX guide presented a more physiological distribution of myelinated and non-myelinated fibers in respect to TCC guides. Fibrobalsts appeared to form an envelope around NBX guides which apparently helped the sliding of the guide in the freely moving animal. However, fibroblastic infiltration was nearly absent the regenerated nerve inside NBX guides while it was present in TCC guides. A notable characteristic was the good distribution of small intraneural capillary vessels in NBX guides, in contrast with TCC guides (figure 1).
CONCLUSION: A flat, rigid, non-degradable nerve-guide which avoids the use of stitches, perfomed better than a traditional degradable cylindrical nerve-guide. The emploied materials (PMMA and acrylate glue) are not acknowledged as good promoters of a better nerve regeneration, so Authors concluded that the different physical characteristics of the guide may be correlated with the effectiveness of nerve regeneration occuring inside NBX guides.
Figure 1: TEM showing fibroblasts, macrophages and vessels inside a TCC
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