Effect Of Osteoprotegerin Combined With Deproteinized Bone On Early Tendon-bone Healing After Anterior Cruciate Ligament Reconstruction In Rabbits

Objective: To discuss the effect of osteoprotegerin(OPG) combined with deproteinized bone(DPB) on early tendon-bone healing after anterior cruciate ligament(ACL) reconstruction in rabbits.To research the effect and probably mechanism of the complex of OPG/DPB promoting tendon-bone healing,to provide the basic theory for the therapy in the filed of ACL injury.Methods:Fresh metaphysis cancellous bone was took from femur of newborn calf,which was cut into 3mm×3mm×5mm to prepare DPB by way of 20%H2O2 and ether alternating soaking for 24 hours continuous 6 times.DPB was soaked in liquor of OPG to prepare the complex of OPG/DPB.A total of 80 New Zealand grow up health white rabbits(Provided by experimental animal center of Guilin medical University),weighing(2.5~3.5)kg,which were divided randomly into 4 groups(n=20):group A(OPG),group B(DPB),group C(OPG/DPB) and group D(CONTROL).After the experimental animals were anesthetized by 10% chloral hydrate,there left ACL were operated to build the model of ACL injuries and then reconstructed it by autologous tendon visually.The bone tunnels were filled with substances correspondingly,but only by autologous tendon in control group.Each experimental animal was given 50000 units gentamicin during operation to prevent infection.After operation each experimental animal was gave gentamicin continuous three days to avoid inflammatory.The general conditions of the experimental animals were observed postoperatively,six experimental animals were killed randomly 4,8 and 12 weeks postoperatively in each group.The specimens of the knee joints were used for general observation,biomechanical test and observing the histologic of tendon-bone interface by microscope.Results:General pathologic The tendon-bone interface were filled with soft tissue and then cartilage and at last were bone tissue in group A and C,it became mature gradually in group B and D,but poor bone formation,few of the specimens presented obvious bone tunnel enlargement.Biomechanical test 4 weeks after operation,the differences of maximum tension of the transplanted ligaments in each group had no significance(P>0.05);At 8 weeks,the maximum tension of group C was higher than group A,the maximum tension of group A was higher than group B and D, the difference between group A and C had significance,so as to the comparision between group A and B(P<0.05);The difference between group B and D had no significance(P>0.05).At 12 weeks,the differences had no significance among groups(P>0.05).Histological observation 4 weeks after operation,the bone tunnel were filled with fibrous connective tissue;At 8 weeks,soft tissue arranged closely,Sharpey type textile fiber arranged more regular in group C than other groups;At 12 weeks,the bone tunnel matured gradually,forming a continuous fibrocartilage connection in group B and D;The bone tunnel of group A and C were almost filled with newly formed bone, which formed a “tidal line” healing structure,fibrocartilage arranged more regular in group C than group A.Conclusion:OPG and the mixture of OPG/DPB can promote early tendon-bone healing after ACL reconstruction,the mixture of OPG/DPB has a batter effect than OPG.