| ObjectiveBy the animal model of anterior cruciate ligament reconstruction, to observe the effects of ACL reconstruction with preserving the remnant and removeing the remnant on healing of ACL autograft and collagen phenotype, and discuss the reasons of the effects, provid the theoretical basis for the preserving-remnant technique.Methods1. Experimantal treatment:The thirty-six mature New Zealand White rabbits were adopted in the experiment, the normal control group consists of four rabbits of them. Remaining rabbits were divided into four groups at random, each group had 8 rabbits.The anterior cruciate ligament of the rabbit was cut off, the remnant of original ACL was preserved on the left and removed on the right, then single bundle anterior cruciate ligament reconstruction was conducted with ipsilateral achilles tendon graft. After the operation, the animals in 4 groups were feeded for 6, 12, 18, 24 weeks postoperatively to observate the function of knees and get the specimens.2. Observation indexes:2.1 Function Assessmant Score:The active motion, passive motion and joint stability of the knee were observated and recorded at 6, 12, 18, 24 weeks postoperatively.2.2 Histological Observation:2.2.1 Intra-articular segment of the grafts:The knee specimens were fixed with 4% paraformaldehyde. The specimens were taken and embeded, sliced, and then strained with HE, Picric acid-Sirius red, Immunofluorescence of typeⅢcollagen to observe fibroblast density, collagen phenotype and histopathological situation.2.2.2 Tibial tunnel segment of the grafts:The knee specimens were decalcified with 10% EDTA-Na2. The specimens were taken and embeded, sliced, and then strained with HE and toluidine blue to observe tendon-bone healing situation.3. Statistical Analysis: Then the data was collected to make the statistical analysis with SPSS16.0.Results1. Function Assessmant Score:In each time section, Function Assessmant Score of the knee in preserving-remnant group was higher than that in removing-remnant group, there was significant difference between two groups(P<0.05); There wasn't significant difference among different time sections in each treatment group(P>0.05); There wasn't interaction between whether or not to preserve the remnant and time(P>0.05).2. Intra-articular segment of the grafts:HE staining: In each time section, the histopathological situation in preserving-remnant group was better than that in removing-remnant group. In each time section, the fibroblast density in preserving-remnant group was higher than that in removing-remnant group, there was significant difference between two groups(P<0.05); The density of 12 week time section was higher than 6, 18, 24 week time section, there was significant difference among different time sections in each treatment group(P<0.05); There wasn't interaction between whether or not to preserve the remnant and time(P>0.05). Sirius red staining: In each time section, the percentage of typeⅢcollagen in preserving-remnant group was higher than that in removing-remnant group, there was significant difference between two groups(P<0.05); The percentage of 12 week time section was higher than 6, 18, 24 week time section, there was significant difference among different time sections in each treatment group(P<0.05); There was significant difference between each treatment group and normal achilles tendon group on 24 week time section (P<0.05), this shows that the grafts undergoes the process of collagen remodeling and "re-ligaments"; There was significant difference between each treatment group and normal ACL group on 24 week time section (P<0.05), this shows that there was histopathological difference between two groups, the process of collagen remodeling was not completed.Immunofluorescence staining of typeⅢcollagen: In each time section, the fluorescence expression of typeⅢcollagen in preserving-remnant group was higher than removing-remnant group, there was significant difference between two groups(P<0.05); The fluorescence expression of 12 week time section was higher than 6, 18, 24 week time section, there wasn't significant difference among different time sections in each treatment group(P>0.05); There wasn't interaction between whether or not to preserve the remnant and time(P>0.05).3. Tibial tunnel segment of the grafts:HE and toluidine blue staining: In each time section, the histopathological situation of tendon-bone healing and metachromasia of cartilage cells in preserving-remnant group was higher than that in removing-remnant group. the process of tendon-bone healing in removing-remnant group was delayed than that in preserving-remnant group.Conclusion1.The ACL reconstruction by preserving-remnant can promote the postoperative restoration of knee's function.2.The ACL reconstruction by preserving-remnant is beneficial to the newborn cells growing of the intra-articular segment of the grafts.3.The ACL reconstruction by preserving-remnant is beneficial to the "creeping substitution" of typeⅢc ollagen of intra-articular segment of the grafts and to convert to typeⅠc ollagen, and promote the process of tendon graft "ligaments".4.The ACL reconstruction by preserving-remnant can promote the tendon-bone healing of tibial tunnel segment of the grafts. |
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