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Use of Peripheral Nerve Allograft in the Repair of Long- Segmental Nerve Defects Resulting from Gun-Shot Wounds Sustained During Operation Enduring Freedom
Patrick L. Basile; RT Howard; IL Valerio; GF Santiago
National Naval Medical Center, Bethesda, MD, USA
Introduction: Gunshot wounds to the extremities are a frequently encountered mechanism of injury in Operation Enduring Freedom Significant Peripheral nerve damage is common after such injuries and autologous repair is often complicated by the inability to harvest donor nerves of adequate length, diameter and fascicular organization [1].
Methods: The authors present two cases of patients who suffered penetrating gunshot wounds to the lower extremities resulting in long segmental nerve defects. Repairs of a 5 cm sciatic nerve and a 9 cm tibial nerve defect were performed using large diameter nerve allografts (Axogen AvanceTM nerve allograft). Physical exam as well as Nerve conduction studies were used to determine sensory and motor function of muscle groups distal to nerve coaptation. Muscle strength was assessed according to the British Medical Research Council Scale.
Results: Mean follow-up ranged from 12-18 months. Nerve conduction performed at 12 months following 9 cm Right Tibial nerve allograft showed low amplitude Compound Muscle Action Potential of 0.4 mV of the Tibial nerve. Strength was measured to be M4 in foot invertors, M5 in foot plantarflexors, M4 in Toe flexors. The medial and lateral plantar foot, including heel,was sensitive to deep pressure only. Nerve conduction performed at 12 months following left 5 cm sciatic nerve allograft showed absence of nerve conduction with stimulation of the tibial and peroneal nerves. Strength was measured to be M3 in left dorsiflexors, M4 in left plantarflexors, and M3 in the left extensor hallicus longus. Two-point discrimination performed at 18 months showed full sensation of the medial and lateral dorsal foot and 1st t toe web-space. There was no sensation of the plantar surface of the foot.
Conclusion: Early follow up suggests there is a significant role for the use of nerve allograft in the management of long-segment peripheral nerve injuries. Exam findings at one year are consistent with successful motor re-innervation distal to allograft. Continued follow-up is necessary to determine sensory re-innervation and utility of long-segment peripheral nerve allografts.
References:
1. Yang et. Al. Sciatic nerve repair by reinforced nerve conduits made of gelatin–tricalcium phosphate composites. Journal of Biomedical Materials Research Part A, 96A: 288–300.
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