Regeneration across 'stepping-stone' nerve grafts.

The ability of small nerve segments interposed between synthetic conduits to increase the total nerve gap distance across which successful nerve regeneration would occur was studied. Fifty adult male Lewis rats were randomized into five groups. In Group I a segment of resected sciatic nerve was repaired by a nerve graft. Group II had alternating silicone tubing/nerve graft/silicone tubing replacement of the resected nerve segment (single stepping stone group). Group III had silicone tubing/nerve graft/silicone tubing/nerve graft/silicone tubing repair of the nerve deficit (double stepping stone). Group IV had a single long silicone conduit repair. Group V control underwent a sham operation. Nerve regeneration was evaluated using walking track pattern analysis, electrophysiologic assessment and histomorphological evaluation. 'Stepping stone nerve grafts' enhanced regeneration across nerve gaps in comparison to a single long conduit, but were inferior to a single long nerve graft. In the repair of long nerve gaps, the use of multiple short conduits with interposed short nerve segments could provide a source of trophic factors to enhance regeneration.