Experimental study of peripheral nerve injury during gradual limb elongation.

The purpose of this study was to clarify how fast the peripheral nerve can be elongated gradually without inducing nerve conduction block, and to assess whether the damage to the peripheral nerve is reversible. Rabbit femur was gradually elongated to 30 mm at the rate of 0.8 mm/day, 2.0 mm/day, and 4.0 mm/day to stretch the sciatic nerve. Immediately after and eight weeks after elongation, each group was estimated. Elongation of the Ranvier's node, which was likely the cause of conduction block, was observed and its severity increased with elongation speed. There was no Wallerian degeneration even when conduction block was complete. There was little damage to the sciatic nerve in the group of 0.8 mm/day. Damage in the group of 2.0 mm/day immediately after elongation had a tendency to recover by eight weeks, but there was no such tendency in the group of 4.0 mm/day.