| Part one:Establishment of aseptic nonunion model of tibial fracture after LCP internal fixation in rabbitsObjective:The model of aseptic nonunion of tibial fracture after LCP fixation in New Zealand rabbits was established to provide the basis for the subsequent experimental study on the treatment of aseptic nonunion of tibial fracture treated by LCP in rabbits.Methods:Eighteen healthy adult male white rabbits were divided into control group and experimental group according to different intraoperative treatment methods.In the experimental group,the right tibia was truncated and isolated with bone wax at the fracture end,and the LCP was locked and fixed.LCP was locked and fixed after osteotomy in the control group.X-ray examination was performed in the two groups at 2、4、8 and 12 weeks respectively.Gross specimen observation and histopathological examination were performed in the control group at the time of fracture healing,and the same examination was performed in the experimental group at 12 weeks after surgery to observe the fracture healing.Results:X-ray,gross specimen observation and histopathological examination showed that bone healing could be achieved at 4w after fracture operation in the control group.In the experimental group,bone nonunion was diagnosed at 12 W.Conclusion:This method can establish a practical animal experimental model of aseptic bone nonunion after LCP fixation,which can lay a foundation for subsequent experimental studies.Part two:Clinical observation on of tibial nonunion treated with"dynamization" combined with autologous bone graft after LCP internal fixation in rabbitsObjective:To observe the clinical effect of LCP "dynamic" combined with autologous bone graft in treatment of rabbit tibial nonunion.Methods:Forty-five model rabbits were randomly divided into three groups,group A removed the bone wax at the broken end of the fracture;In group B,bone wax was removed and bone grafte was preformed;Group C underwent the same process as group B,what else LCP "dynamization" was preformed.X-ray examination was performed at 2、4、6 and 8 weeks after intervention to compare Lane-Sandhu fracture healing scores.At 4、6 and 8 weeks after the intervention,bone tissues were taken from the fracture healing site from 3 rabbits in each group for pathological examination to observe the bone healing.At 8 weeks after operation,all the remainder rabbits were sacrificed and divided into three groups:group A(normal bone specimen)and group B(right tibia specimen of group B).Group C(right tibia specimen of group C);Three point bending test was performed and the maximum bending force and bending strength of each group were compared.Results:At 2 and 4 weeks after the intervention operation,there was no significant difference in X-ray scores among the three groups.At 6 and 8 weeks after surgery,the X-ray scores of the group C were significantly higher than those of the group B(P<0.05).Pathological examination showed that at 4,6 and 8 W after intervention,the bone healing process of group C was better than that of group B and group A.The three-point flexural mechanics test showed that the maximum flexural strength and bending strength of group C>group A(P<0.05).Conclusion:LCP "dynamization" combined with autologous bone graft could accelerate progress of fracture healing,Early tibia specimens showed stronger flexural resistance and higher bone quality.Part three:A preliminary study on the mechanism of osteogenesis of LCP"dynamization"combined with autologous bone graft in the treatment of rabbit tibial shaft nonunionObjective:To observe the effect of LCP "dynamization" combined with autograft,and to explore the preliminary possible mechanism of LCP "dynamization" in promoting bone nonunion healing.Methods:Twenty-seven animal models were divided into three groups:group A removed the bone wax at the broken end of the fracture;In group B,bone wax was removed and bone grafte was preformed;Group C underwent the same process as group B,what else LCP "dynamization" was preformed.X-ray examinations were performed at 2、4、6、and 8 weeks after the intervention,and Lane-Sandhu X-ray scores were compared.Serum samples were collected at 2、4、8、12、14、16、18,and 20w after model establishment respectively.BALP,PINP,CTX,TGF-β1 levels were detected and compared.At 4、6 and 8 weeks after the intervention,the bone specimens from the fracture healing site of 3 rabbits were taken for Western Blot detection,and the protein expression differences of BALP,BMP-2 and BMP-4 in each group were observedResults:At the 16、18 and 20 weeks,X-ray scores in group B and C were significantly higher than those in group A,and at the 16 and 18 weeks,X-ray scores in group C were significantly higher than those in group B(P<0.05).ELISA showed that BALP level in group C>group B>group A at 14、16 and 18 weeks;TGF-β1 level in group C>group A at 14 weeks,group C>group B>group A at 16、18 weeks,group B>group C>group A at 20 weeks;PINP level of group C was higher than group A and B at 14 weeks,and that in group B and C was higher than group A at 16、18 and 20 weeks.At 14 weeks,CTX level of group C was higher than group A and B,and group B>group C>group A at 20 weeks(P<0.05).Western Blot detection showed that at 4,6 and 8w after intervention,the protein expression content of group C>group B>group A(P<0.05).Conclusion:The "dynamization" of LCP can promote the generation of bone transformation markers,improve the expression of osteogenic proteins at fracture site,which accelerate the formation of bone callus and bone shaping,and promote fracture healing. |
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