| Objective: The model of autogenous nerve transplantation in rabbit sciatic nerve defect provided theoretical basis for finding an ideal nerve repair method in clinic.Methods: According to their body weight,Seventy-two healthy New Zealand female rabbits(age:2 months or more,weight: 2.5-3.0kg)were divided into four groups by the method of random block design.There were 18 rabbits in each group.Group A represented vascularized nerve anterograde transplantation.Group B represented Non-vascularized nerve anterograde transplantation.Group C represented Vascularized nerve reverse transplantation.Group D represented Non-vascularized nerve reverse transplantation.The right thigh is the operative side.The left thigh is the non-operative side.The samples were taken from each group at 4?8 and 12 weeks after surgery.The general observation of rabbit body and transplanting nerve,nerve electrophysiological examination,nerve conduction velocity comparison,tibial anterior muscle wet weight recovery rate detection and comparison,the observation of sciatic nerve pathological section HE staining and myelinated nerve fiber recovery rate comparison were used for evaluating the effect of nerve transplantation.Results:1.General observation:All postoperative animals had claudication,foot drooping and foot ulcer at 4 weeks.Some rabbits suffered from anemia due to bleeding of foot ulcer.Most rabbits lost weight.The right shank muscles were weak in tension.and the muscles were partly atrophied.The anterior tibial muscle atrophy was obvious.At 8 weeks,the postoperative animals were still claudication.The claudication was slightly improved than that at the 4th week.The foot ulcer of individual animals were crusted,and the shank muscles were further atrophied.At 12 weeks,the animals were still limping.The drooping feet got well.Most foot ulcer had scabs and some foot ulcers had healed.Soft tissue hyperplasia,dry skin and desquamation could be seen in the operative foot.The degree of atrophy tended to be stable.The atrophy of tibial anterior muscle was obvious.2.The observation of nerve grafts Group A(vascularized nerve anterograde transplantation group): At 4 weeks,there was tissue proliferation,edema and adhesion around the graft segment.The diameter of which was about 2 times the diameter of the normal nerve.With the increase of time,the adhesion of tissue proliferation and edema decreased gradually.At 12 weeks,the surface of the epineurium was smooth.The appearance of the nerve was similar to that of the normal nerve.The adhesion was less.It was easy to separate from normal tissue.There was a little connective tissue around the anastomotic stoma.The new epineurium is similar to the normal epineurium.The neuroma and glioma were not seen in most of them.When the neural stem was stimulated,the evasion of the right leg was responsive sensitively.Group B(Non-vascularized nerve anterograde transplantation group): Proliferation edema and adhesion tissue were observed around the nerve graft at 4 weeks.The diameter of the nerve graft was about 2.5 times the diameter of the normal nerve.The adhesion was heavy and it was hard to separate from the normal tissue.At 12 weeks,most of the transplanted nerves were similar to the normal nerves.The new epineurium had been formed.The epineurium was thick.The distal nerve had no obvious changes in shape,and the neuroma and glioma was often seen at anastomotic stoma.The right leg was not sensitive to pain stimulation.Group C(Vascularized nerve reverse transplantation group)Proliferous dropsical and adherent tissue around nerve graft segment at 4 weeks.The diameter of the nerve was about 2 times that of the normal nerve.At the 8th and 12 th week,it was found that the cicatricial tissue was gradually decreasing.At 12 weeks,there were fewer adhesions around the transplanted nerve segment.The new epineurium formed,and the appearance of the nerve was slightly thicker than that of the normal nerve.There are a few neuromas in the anastomosis.When the neural stem was stimulated,the evasion of the right leg was responsive sensitively.Group D(Non-vascularized nerve reverse transplantation group): Proliferative adhesions were seen around the nerve graft segment at 4 weeks.The diameter of the nerve was about 3 times that of the normal nerve.The adhesion was severe and the nerve was difficult to free.At the 12 th week,the diameter of most grafts was thicker than that of the normal nerve,and the nerve-tumor was often found at the anastomosis.The shape of the distal nerve was not changed obviously.The right leg was not sensitive to pain stimulation.3.Electrophysiological examination and comparison of nerve conduction velocities At 4 and 8 weeks,there was no effective Compound Muscle Action Potential in each group.At 12 weeks,all four groups were able to elicit effective CMAP.Comparison of nerve conduction velocities: the nerve conduction velocities of group A and group C were better than those of group B and group D(P < 0.05).There was no significant difference between the anterograde and retrograde placement groups(P > 0.05).4.Detection and comparison of wet weight recovery rate of anterior tibial muscle At 4 weeks,the wet weight of the tibial anterior muscles decreased by about 40% in the four groups,and there was no statistical difference between the groups(P > 0.05).At 8 weeks,the wet weight of the tibial anterior muscles decreased by about 55% in the four groups,and there was no statistical difference between the groups(P > 0.05).At 12 weeks,the wet weight of tibial anterior muscle decreased about 59% in vascular group,while in Non-vascular group,the wet weight of tibia anterior muscle decreased about 66%.The recovery rate of muscle wet weight in the vascular graft group was better than that in the non-vascular graft group(P < 0.05).There was no statistical difference between anterograde placement and retrograde placement(P > 0.05).5.Observation of HE staining in pathological section of sciatic nerve The regenerated nerve fibers in the vascularized group are more abundant and mature than those in the non-vascularized group.The nerve fiber connective tissue with blood vessel group is less than that without blood vessel group.That is,vascularized nerve transplantation is better than non-vascular nerve transplantation.6.Comparison of regenerative axon recovery rate The vascularized group was superior to the non-vascularized group(P < 0.05),which had statistical significance.That is,vascularized nerve transplantation is beneficial to the regeneration of myelinated nerve fibers.There was no statistical difference between the anterograde placement group and the retrograde placement group(P > 0.05).Conclusion:1.Four different transplantation methods are effective for nerve defect repair.2.The good blood circulation of the transplanted segment can promote nerve regeneration.3.No significant difference has been found between anterograde and retrograde placement of autologous nerve graft. |
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