Nerve regeneration through collagen tubes

Severe nerve injuries may require microsurgical grafting to span a defect. Introduction of graft material into a highly vascular recipient bed is documented to aid in early regeneration of neuronal blood supply. A silicone rod (SR)-induced fibrovascular sheath was employed to evaluate the regeneration of rat tibial nerve through 2-mm-diameter collagen tubes (CT) or contralateral nerve autografts (AUTO). At first operation, 5 mm of right tibial nerve was resected from 30 retired male breeder Sprague-Dawley rats. Resected nerve was replaced with either a 5 X 2 mm SR or the nerve ends were sutured to the intermuscular fascia. Four weeks later, animals were repaired by replacing the SR with either a CT or a contralateral AUTO from the left tibial nerve. Three months later, EMG testing was performed, and histologic sections were prepared. The EMG latency and the size of the compound action potential for sheathed or non-sheathed CT or AUTO were statistically superior to controls at the 95% confidence level. All other intergroup comparisons of latency and action potential size were statistically insignificant. The proportion of nerve fibers traversing the surgical sites was not influenced by the method of repair or by the presence or absence of sheathing. Tubulized repairs most closely resembled unoperated nerves, and autografted repairs had a large diameter, but much fibrosis, whereas controls displayed immaturity and disorganization. Our observations suggest that there was no difference between repairs performed with or without a vascular pseudosheath. However, CT supported regeneration better than did AUTO repair.