Evaluation of two collagen conduits and autograft in rabbit sciatic nerve regeneration with quantitative magnetic resonance DTI, electrophysiology, and histology.

BACKGROUND: We compared different surgical techniques for nerve regeneration in a rabbit sciatic nerve gap model using magnetic resonance diffusion tensor imaging (DTI), electrophysiology, limb function, and histology. METHODS: A total of 24 male New Zealand white rabbits were randomized into three groups: autograft (n = 8), hollow conduit (n = 8), and collagen-filled conduit (n = 8). A 10-mm segment of the rabbit proximal sciatic nerve was cut, and autograft or collagen conduit was used to bridge the gap. DTI on a 3-T system was performed preoperatively and 13 weeks after surgery using the contralateral, nonoperated nerve as a control. RESULTS: Overall, autograft performed better compared with both conduit groups. Differences in axonal diameter were significant (autograft > hollow conduit > collagen-filled conduit) at 13 weeks (autograft vs. hollow conduit, p = 0.001, and hollow conduit vs. collagen-filled conduit, p < 0.001). Significant group differences were found for axial diffusivity but not for any of the other DTI metrics (autograft > hollow conduit > collagen-filled conduit) (autograft vs. hollow conduit, p = 0.001 and hollow conduit vs. collagen-filled conduit, p = 0.021). As compared with hollow conduit (autograft > collagen-filled conduit > hollow conduit), collagen-filled conduit animals demonstrated a nonsignificant increased maximum tetanic force. CONCLUSIONS: Autograft-treated rabbits demonstrated improved sciatic nerve regeneration compared with collagen-filled and hollow conduits as assessed by histologic, functional, and DTI parameters at 13 weeks.