ABSTRACT
This experimental study evaluated denatured skeletal muscle and denatured 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 1 (control), the segment
was discarded; in Group 2, the segment was re-implanted orthotopically; in Group 3,
the defect was bridged 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 at 1.5, 2, 2.5, 3, and 6 months postoperatively. At 6 months, a
Grass neurostimulator was used to determine the minimal voltage necessary to elicit
ankle motion.
Hind-foot ulceration and/or toe loss occurred in all groups, but less commonly in
the rats with denatured muscle and denatured nerve conduits. Both Groups 3 and 4 achieved
a macroscopic appearance of nerve at 45 days. However, the denatured conduits were
longer and narrower than in standard nerve grafts. In the distal nerve, a mixture
of axonal regeneration and degeneration was seen in Groups 2 to 4. By 6 months, the
microscopic appearance of the nerve grafts, conduits, and distal nerves was that of
normal nerve, with no differences between the groups. Active plantar flexion following
electrical stimulation was observed in Groups 2 to 4 at 6 months. The voltage required
to 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 throughout the 6 months
of observation. Results indicated that denatured skeletal muscle and denatured epineural
basement membrane tubes can act as matrices for the growth of regenerating axons.
They appear to facilitate protective sensory recovery more rapidly and motor recovery
(as determined by electrical stimulation) less effectively than conventional nerve
grafts.
