Peripheral nerve lengthening by controlled isolated distraction: a new animal model

We have developed a simple and effective animal model to study: the distrac tion neurogenesis utilizing the sciatic nerve-lengthening technique in rats . The model allows macroscopic, physiological, anti histological evaluation of the distraction site. Fourteen adult Harlan Sprague Dawley rats (300-35 0 g) were used in this study. A 10 mm segment of the right sciatic nerve of each animal in the nerve-lengthening group was resected. Gradual nerve len gthening was performed by advancing the proximal nerve stump at a rate of 1 mm/day. The proximal stump neuroma was then dissected and a direct nerve a nastomosis was performed. On the left side a standard autogenous nerve-graf ting procedure was performed with a 10 mm segment of sciatic nerve used as an in situ nerve graft. Three months after the second surgery, the sciatic nerves were exposed rind investigated by gross observation and EMG followed by histological processing and tissue analysis. Neomicrovascularization wa s observed surrounding the sciatic nerve anastomosis in all five specimens of the nerve-lengthening group as compared to the more white-colored scar t issue that was observed in the nerve-grafting group. The EMG results were s imilar for both groups. Histological studies of the lengthened nerves showe d axon morphology equivalent to the grafted nerves. This study demonstrated a clear evidence of the successful nerve regeneration within a segmental n erve gap by serve lengthening. (C) 2001 Orthopaedic Research Society. Publi shed by Elsevier Science Ltd. All rights reserved.