DENATURED MUSCLE AS A NERVE CONDUIT - A FUNCTIONAL, MORPHOLOGIC, AND ELECTROPHYSIOLOGIC EVALUATION

This experimental study evaluated denatured skeletal muscle and denatu red epineural basement membrane tube as conduits to bridge defects in rat sciatic nerve. A 1-cm segment of sciatic nerve was resected in 48 rats. In Group I (control), the segment was discarded; in Group 2, the segment was re-implanted orthotopically; in Group 3, the defect was b ridged by denatured (liquid nitrogen frozen and thawed) muscle; and in Group 4, the resected nerve segment was denatured as in Group 3, the axons removed, and the resulting epineural basement membrane tube used as a conduit. Functional assessment was carried out with the sciatic functional index (SFI). Histologic examination of the graft was made a t 1.5, 2, 2.5, 3, and 6 months postoperatively At 6 months, a Grass ne urostimulator was used to determine the minimal voltage necessary to e licit ankle motion. Hind-foot ulceration and/or toe loss occurred in a ll groups, but less commonly in the rats with denatured muscle and den atured nerve conduits. Both Groups 3 and 4 achieved a macroscopic appe arance of nerve at 45 days. However, the denatured conduits were longe r and narrower than in standard nerve grafts. In the distal nerve, a m ixture of axonal regeneration and degeneration was seen in Groups 2 to 4. By 6 months, the microscopic appearance of the nerve grafts, condu its, and distal nerves was that of normal nerve, with no differences b etween the groups. Active plantar flexion following electrical stimula tion was observed in Groups 2 to 4 at 6 months. The voltage required t o elicit ankle motion was greater in Groups 3 and 4 than in Group 2 (p < 0.001). Gait was impaired (SFI = -100) in all four groups throughou t the 6 months of observation. Results indicated that denatured skelet al muscle and denatured epineural basement membrane tubes can act as m atrices for the growth of regenerating axons. They appear to facilitat e protective sensory recovery more rapidly and motor recovery (as dete rmined by electrical stimulation) less effectively than conventional n erve grafts.