BACKGROUND: It has been shown that irradiation to the neurolemma can reduce immunogenicity. However, it is still poorly understood whether the degenerated nerve can affect peripheral nerve regeneration. OBJECTIVE: To observe the effect of radiation-damaged nerve transplantation on functional recovery of the peripheral nerve. DESIGN, TIME AND SETTING: Self-control animal trial was performed at the Experimental Center of Orthopedics, Tangdu Hospital of Fourth Military Medical University from January to October 2005. MATERIALS: Fifty-four healthy, Chinese rabbits, irrespective of gender, were randomly divided into experimental (n = 36) and control (n = 18) groups. A 60 Co γ-radiation machine and NDI-200 nerve electro-myograph were provided by the Experimental Center of Orthopedics, Tangdu Hospital of Fourth Military Medical University. METHODS: A median incision was made in the posterior right thigh of rabbits after abdominal anesthesia. A 30-mm segment of sciatic nerve was excised from the inferior margin of the piriform muscle to the tibiofibular intersection. The sciatic nerve in the experimental group was sterilely radiated with 350 Gy for 9.5 minutes. The damaged nerve segment was then re-transplanted. In the control group, the sciatic nerve was re-transplanted directly following excision. Nerve conduction velocity was determined at 4, 6, and 8 months post-surgery. MAIN OUTCOME MEASURES: Functional assessments, such as gait, nutritional status of skin on dorsum of foot, toe spreading reflex, and foot holding, were made between 1 and 180 days post-surgery. The common peroneal nerve and tibial nerve reflexes under clamping were observed at 4, 6, and 8 months post-surgery to evaluate functional restoration of the peripheral nerve. Electromyogram was performed to observe nerve conduction velocity. RESULTS: From postoperative days 1 to 26, the limbs that were transplanted with irradiated nerve exhib- ited dragged walking, foot drop, sole ulcers, depilation, self-induced injury to the toes, and other denervation behaviors. From 95 to 120 days after re-transplantation, the ulcers recovered, in addition to recovered toe-spreading reflex. When subjected to the clamping text, nerve reflex occurred. Compared with animals transplanted with normal nerve, nerve conduction velocity in the experimental group was slower at 4 and 6 months post-surgery (P < 0.05 and P < 0.01). At 8 months after surgery, nerve conduction velocity recovered in the experimental group, but was still slower than the control group (P < 0.05). Recovered conduction velocity in the experimental group was significantly faster than the control group (P < 0.05). CONCLUSION: Reinnervation was achieved by pre-treating a 30-mm segment of sciatic nerve with 350-Gy radiation. Although radiation improved nerve conduction velocity recovery following re-transplantation, the velocity was not completely recovered to normal levels.
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