Effect of diphosphonate on biochemistry change in subchondral bone of unstable rabbit knee joints

Abstract

Objective To explore the effect of diphosphonate on expression of matrix metalloproteinase-9(MMP-9) and cathepsin K(CK) in subchondral bone of unstable rabbit knee joints.Methods Fifty male New Zealand white rabbits were divided randomly into three groups according to random digits table:the control group (n=10),the model group (n=20).the diphosphonate group (n=20).Hulth model of unstable rabbit knee joint was achieved in the right knee joint.Ten rabbits from the diphosphonate group and 5 rabbits from the control group were sacrificed by aeroembolism at the second and tenth week postoperatively,respectively.Then the medial femoral condyles of the right knee were harvested.Specimens were processed for immunohistochemical analysis of MMP-9 and CK.Results Cells with expression of MMP-9 and CK could be found in the three groups at the second and tenth week after operation.Compared with the control group,there was a significant increase in the number of cells with expression of MMP-9 and CK in model group at the second and tenth week after operation.Diphosphonate could inhibit expression of MMP-9 and CK in cells.Compared with the model group,the number of cells with expression of MMP-9 and CK in diphosphonate group was fewer; there was a statistical significance between them.Conclusion Diphosphonate can inhibit the expression of MMP-9 and CK in subchondral bone of unstable rabbit knee joints,which can resist the bone resorption and protect articular cartilage. Key words: Osteoarthritis; Matrix metalloproteinase 9; Cathepsins; Diphosphonates