Zone of traction injury of the common peroneal nerve.

The history of functional motor recovery after reconstruction of traction injury to the common peroneal nerve is poor, regardless of technique and regardless of the experience of the surgeon doing the reconstruction. The hypothesis tested is that the failure of functional motor recovery after common peroneal nerve traction injury is because the zone of injury extends beyond the visible region of peroneal nerve in continuity injury and into the muscle entry zone of the motor nerve terminations. The opportunity arose to examine pathologically this suspected distal zone of injury in one patient. Histology from this patient was compared with that from a similar zone in a leg amputated for vascular indications. With a peroneal traction injury severe enough to cause disruption of the nerve, histology using Masson trichrome stain for collagen, neurofilament and S-100 stain for nerve fibers and Schwann cells demonstrated collagen deposition between the peroneal nerve and the muscle. This fibrosis was not seen in the in the same location from the amputation specimen. These findings were corroborated by electron microscopy of the myoneural junction in both specimens. It is concluded that stretch/traction injury zone extends into the myoneural junction, preventing otherwise successful neural regeneration through nerve grafts to reinnervate muscle. This suggests that with a distal zone of injury extending into the myoneural junction region, peroneal motor function may be better achieved by direct neurotization than with nerve grafting.