| Objective : This study was designed to compare the radiological and histological changes of the repaired bone defects under different treatment methods and during different periods.Meanwhile,it was aimed to observe the effect of allogenic platelet rich plasma clinical combined with bone grafting on the repair of bone defect,so as to provide a theoretical basis and practical guidance for clinical treatment.Methods:1 Experimental group: After a bone defect model was established in the rabbit lower limb femoral medial condyle,the 36 healthy New Zealand white rabbits were randomly divided into two groups: group A(n = 18),allogeneic bone allografts Platelet plasma implantation,group B(control group,n = 18),simple implantation of allogeneic bone,and the other 6 to establish a simple bone defect model as a blank group.2 Preparation of allogeneic PRP: The heart blood 50 ml were transferred to 10 ml centrifuge tube for the second centrifugation,the first time to 200 g centrifugal force,centrifugation 10 min,the second 200 g centrifugal force of the same time,PRP prepared about 1ml,PRP and allogeneic Bone was blended in a 2: 1 ratio to obtain a complex PRP gel.3 Platelet counting: After the blood was taken from the heart and take vein blood samples into hemocytometer to get the amount of the platelets.The PRP was prepared by method with reference to the Landesberg method and verify PRP platelet count whether the preparation of the PRP meet the experimental requirements.4 Observation and evaluation: The animals were sacrificed by excessive anesthesia of experimental animal.Firstly,we set the exposure conditions specific perturbation of the femoral condyle and X-ray(1m 220 KV,30mA.distance,exposure time 0.15s)to observe the bone defect bone graft healing.According to the Yang's radiographic scoring criteria,the resistance values of the upper,middle and lower three points of the bone defect area were recorded by X-ray plain film.Then the specimens were taken to observe the gross specimens,and the surface changes of the implant materials and the growth and repair of the implanted bone were observed.Making histological and immunohistochemical staining,observe the regeneration and repair of bone defects in rabbits under an optical microscope,and score according to the standard for evaluation of Lane's bone repair in each animal.The application of image analysis system(HMIAS-2000)and the professional image analysis software(Image-Pro Plus)to calculate the average optical density of positive cells the immunohistochemical slices(Mean Optical Density,MOD)and were conducted statistical analysis.Results:1 General observation: All animal incision healed well,postoperative 4weeks and 8 weeks,A group than the B group of defective tissue repair bone formation more flat,12 weeks after surgery,group A and group B bone tissue defect areas were completely repaired,the border has been unable to distinguish,and there are some heterotopic ossification.2 Whole blood and PRP platelet count: the number of platelets in PRP was in whole blood(4.30±0.28)times,which met the requirements of the Landesberg's method through the preparation of PRP for two times.3 The imaging score and observation results: The radiographic score of X-ray film at 4,8 and 12 weeks postoperatively showed that there was significant difference between A group and B group(P <0.05),A group was significantly higher than B group,and compared the X-ray density of A group and B group after operation in two groups,A group resistance,density value is superior to that of B group,the difference was statistically significant(P<0.05).4 Histological score and microscopic observation: The histological scores of group A and group B were higher than those of control group at 4,8 and 12 weeks postoperatively,and the difference was statistically significant(P<0.05).The results of optical microscopy showed that the area of the experimental group was higher than that of the control group at each time point(P <0.05).The results of immunohistochemistry showed that the mean optical density(MOD)of PDGF and TGF-? immunohistochemistry in group A was significantly higher than that group B(P<0.05),indicating that expression of the amount of PDGF and TGF-protein in fourth and 8 weeks was higher than the control group;At 12 weeks postoperatively,the expression of PDGF and TGF-? protein decreased,and there was no significant difference between the experimental group and the control group(P> 0.05).Conclusion:1 The combination of allogeneic platelet rich plasma and allogeneic bone tissue can promote bone formation and accelerate bone defect repair.2 Platelet derived growth factor(PDGF)and transforming growth factor(TGF-?)decreased significantly after 8 weeks,and they were important growth factors for early bone tissue regeneration.3 The bone defect of the model group was not repaired at 12 weeks postoperatively and the experimental model was established. |
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