摘要
BACKGROUND： Autograft is commonly used to repair nerve deficit. Usually, the choice of donor nerves is based on their similarities in form and structures to the injured nerves. For the reason, the cutaneous antebrachii lateralis nerve is currently considered the most suited for digital nerve repair. OBJECTIVE： To compare early nerve regeneration after transplantation of three different autografts： the greater auricular nerve （GAN）, the saphenous nerve （SN） and the lateral femoral cutaneous nerve （LFCN）. DESIGN： Observational contrast study. SETTING： Department of Plastic Surgery and Burns, Tangdu Hospital, Fourth Military Medical University of Chinese PLA. MATERIALS： A total of 42 New Zealand rabbits, of both genders, 12-14 months old and weighing 2.0- 2.5 kg, were used in this study. In addition, Moller-spetra 900 operating microscope （Germany）, Olympus BX 51 microscope, DP 70 image collecting System （Japan）, BL-420E＋ Biologic function testing System （China）, JEM-100 electron microscope （Japan）, Reichet-JunG820 Cryostat （Swiss）, and Libror-AEG-120 precision analytical Balance （Japan） were also used in this study. METHODS： The experiment was carried out in the Department of Plastic Surgery and Burns, Tangdu Hospital, Fourth Military Medical University of Chinese PLA from April to November 2005. After anaesthesia, the GAN were dissected bilaterally and a 1.2 cm deficit was made in each nerve. The animals were randomly divided into three groups, including GAN group, SN group and LFCN group with 14 in each group. ① Nerve pinch test： At 1, 2, and 4 weeks after operation, three animals in each group were tested. The nerve grafts, along with the proximal and distal GAN segments were exposed and pinched with microsurgical forceps in distal-proximal orientations. The distance between the proximal anastomosis site and the most distal point, where the pinch evoked an ear contraction response, was measured as distance of nerve regeneration. ② Computer image analysis： At 4 and 12 weeks, 2 μm sections were prepared, each stained with either HE or methylene blue to assess axon number and density, cross-section area, and myelin sheath thickness. ③ Electrophysidogical tests： At 12 weeks, the bilateral GAN along with the nerve grafts of 4 animals in each group were exposed. Points A, B and C were marked on each specimen： point A： at the proximal GAN segment, 7 cm from the proximal anastomosis; point B： 0.5 cm from the proximal anastomosis; point C： at the distal GAN segment, 0.5 cm from the distal anastomosis. The whole nerve including nerve graft and proximal and distal GAN segments, as a block, was harvested and immersed in Ren＇s solution for several minutes until its excitability was stabilized. The specimen was then placed on the electrodes of the shield box to examine the action potential and conduction velocity on segment AB and AC with BL-420E＋biologic function testing system. AC/AB would be the recovery rate of action potential on segment AC. ④ Horseradish peroxidase （HRP） fascicle： At 12 weeks, at the site on the distal segment of GAN 1.0 cm from the distal anastomosis of nerve graft, the GAN was crushed by a pair of haemostatic forceps and HRP water solution was injected into the nerve. Two rabbits in GAN group, SN group and LFCN group, after having survived for 24 hours, 36 hours and 48 hours were selected. The C2 ganglion was exposed and the distance from C2 ganglion to HRP injection site was taken as the axoplasmic transport distance, from which the axoplasmic transport velocity and the mean density of the labeled C2 ganglion cells were calculated. MAIN OUTCOME MEASURES： ① The greatest distance of nerve regeneration; ② the axon number and density, cross-section area, and myelin sheath thickness; ③ the action potential and conduction velocity; ④ the axoplasmic transport velocity and the mean density of the labeled C2 ganglion cells. RESULTS： All 42 experimental rabbits were involved in the final analysis. ① The greatest distance of nerve regeneration： At 4 weeks after operation, the greatest distance of nerve regeneration was longer in the SN group than that in the GAN group and the LFCN group [（45.17±2.48）, （41.83±2.32）, （34.83±2.64） mm, P 〈 0.05], while the greatest distance of nerve regeneration was longer in the GAN group than that in theLFCN group （P 〈 0.05）. ② The axon number and density, cross-section area, and myelin sheath thickness： The number of nerve fascicle was the greatest in the GAN group, and the cross-section area was the most; however, ratio between nerve fascicle and cross-section area, and the axon density were lower than those in other two groups （P 〈 0.05-0.01）. In contrast, the axon density was the greatest in the SN group. At 4 weeks after operation, axon density was the most in the SN group, and then the GAN group and the LFCN group. There were significant differences among the three groups （P 〈 0.05-0.01）. At 12 weeks after operation, density of myelinated fiber and axon section area were higher in the SN group than those in other two groups （P 〈 0.05-0.01）. ③ The action potential and conduction velocity： At 12 weeks after operation, the maximal action potential, the recovery rate of action potential and the nerve conduction velocity were the highest in the SN group. HRP-labeled neurons early occurred in C2 ganglion, and the action potential and the recovery rate of action potential were increased （P 〉 0.05）. At 12 weeks after operation, even though the maximal action potential, the recovery rate of action potential and the nerve conduction velocity on segment AB remained similar in different groups, on segment AC, the action potential, the recovery rate of action potential and nerve conduction velocity were greater in the SN group than those in other groups. ④ The axoplasmic transport velocity and the mean density of the labeled C2 ganglion cells： After HRP injection in the SN group, the positive labeled cells in C2 ganglion firstly appeared at 24 hours, and in other two groups, they did not appeared until 36 hours. The density of labeled cells was the greatest in the SN group and the lowest in the LFCN group. The axoplasmic transport velocity in the SN group was also significantly faster than in the GAN group and the LFCN group （P 〈 0.05-0.01）. Otherwise, the axoplasmic transport velocity was faster in the SN group than that in the GAN group and the LFCN group. CONCLUSION： The donor nerve with greater axon number and density can achieve much better effects during early regeneration.
BACKGROUND： Autograft is commonly used to repair nerve deficit. Usually, the choice of donor nerves is based on their similarities in form and structures to the injured nerves. For the reason, the cutaneous antebrachii lateralis nerve is currently considered the most suited for digital nerve repair. OBJECTIVE： To compare early nerve regeneration after transplantation of three different autografts： the greater auricular nerve （GAN）, the saphenous nerve （SN） and the lateral femoral cutaneous nerve （LFCN）. DESIGN： Observational contrast study. SETTING： Department of Plastic Surgery and Burns, Tangdu Hospital, Fourth Military Medical University of Chinese PLA. MATERIALS： A total of 42 New Zealand rabbits, of both genders, 12-14 months old and weighing 2.0- 2.5 kg, were used in this study. In addition, Moller-spetra 900 operating microscope （Germany）, Olympus BX 51 microscope, DP 70 image collecting System （Japan）, BL-420E＋ Biologic function testing System （China）, JEM-100 electron microscope （Japan）, Reichet-JunG820 Cryostat （Swiss）, and Libror-AEG-120 precision analytical Balance （Japan） were also used in this study. METHODS： The experiment was carried out in the Department of Plastic Surgery and Burns, Tangdu Hospital, Fourth Military Medical University of Chinese PLA from April to November 2005. After anaesthesia, the GAN were dissected bilaterally and a 1.2 cm deficit was made in each nerve. The animals were randomly divided into three groups, including GAN group, SN group and LFCN group with 14 in each group. ① Nerve pinch test： At 1, 2, and 4 weeks after operation, three animals in each group were tested. The nerve grafts, along with the proximal and distal GAN segments were exposed and pinched with microsurgical forceps in distal-proximal orientations. The distance between the proximal anastomosis site and the most distal point, where the pinch evoked an ear contraction response, was measured as distance of nerve regeneration. ② Computer image analysis： At 4 and 12 weeks, 2 μm sections were prepared, each stained with either HE or methylene blue to assess axon number and density, cross-section area, and myelin sheath thickness. ③ Electrophysidogical tests： At 12 weeks, the bilateral GAN along with the nerve grafts of 4 animals in each group were exposed. Points A, B and C were marked on each specimen： point A： at the proximal GAN segment, 7 cm from the proximal anastomosis; point B： 0.5 cm from the proximal anastomosis; point C： at the distal GAN segment, 0.5 cm from the distal anastomosis. The whole nerve including nerve graft and proximal and distal GAN segments, as a block, was harvested and immersed in Ren＇s solution for several minutes until its excitability was stabilized. The specimen was then placed on the electrodes of the shield box to examine the action potential and conduction velocity on segment AB and AC with BL-420E＋biologic function testing system. AC/AB would be the recovery rate of action potential on segment AC. ④ Horseradish peroxidase （HRP） fascicle： At 12 weeks, at the site on the distal segment of GAN 1.0 cm from the distal anastomosis of nerve graft, the GAN was crushed by a pair of haemostatic forceps and HRP water solution was injected into the nerve. Two rabbits in GAN group, SN group and LFCN group, after having survived for 24 hours, 36 hours and 48 hours were selected. The C2 ganglion was exposed and the distance from C2 ganglion to HRP injection site was taken as the axoplasmic transport distance, from which the axoplasmic transport velocity and the mean density of the labeled C2 ganglion cells were calculated. MAIN OUTCOME MEASURES： ① The greatest distance of nerve regeneration; ② the axon number and density, cross-section area, and myelin sheath thickness; ③ the action potential and conduction velocity; ④ the axoplasmic transport velocity and the mean density of the labeled C2 ganglion cells. RESULTS： All 42 experimental rabbits were involved in the final analysis. ① The greatest distance of nerve regeneration： At 4 weeks after operation, the greatest distance of nerve regeneration was longer in the SN group than that in the GAN group and the LFCN group [（45.17±2.48）, （41.83±2.32）, （34.83±2.64） mm, P 〈 0.05], while the greatest distance of nerve regeneration was longer in the GAN group than that in theLFCN group （P 〈 0.05）. ② The axon number and density, cross-section area, and myelin sheath thickness： The number of nerve fascicle was the greatest in the GAN group, and the cross-section area was the most; however, ratio between nerve fascicle and cross-section area, and the axon density were lower than those in other two groups （P 〈 0.05-0.01）. In contrast, the axon density was the greatest in the SN group. At 4 weeks after operation, axon density was the most in the SN group, and then the GAN group and the LFCN group. There were significant differences among the three groups （P 〈 0.05-0.01）. At 12 weeks after operation, density of myelinated fiber and axon section area were higher in the SN group than those in other two groups （P 〈 0.05-0.01）. ③ The action potential and conduction velocity： At 12 weeks after operation, the maximal action potential, the recovery rate of action potential and the nerve conduction velocity were the highest in the SN group. HRP-labeled neurons early occurred in C2 ganglion, and the action potential and the recovery rate of action potential were increased （P 〉 0.05）. At 12 weeks after operation, even though the maximal action potential, the recovery rate of action potential and the nerve conduction velocity on segment AB remained similar in different groups, on segment AC, the action potential, the recovery rate of action potential and nerve conduction velocity were greater in the SN group than those in other groups. ④ The axoplasmic transport velocity and the mean density of the labeled C2 ganglion cells： After HRP injection in the SN group, the positive labeled cells in C2 ganglion firstly appeared at 24 hours, and in other two groups, they did not appeared until 36 hours. The density of labeled cells was the greatest in the SN group and the lowest in the LFCN group. The axoplasmic transport velocity in the SN group was also significantly faster than in the GAN group and the LFCN group （P 〈 0.05-0.01）. Otherwise, the axoplasmic transport velocity was faster in the SN group than that in the GAN group and the LFCN group. CONCLUSION： The donor nerve with greater axon number and density can achieve much better effects during early regeneration.
