Study on the mechanical properties of tibial cartilage and subchondral bone

软骨下皮质位于薄层钙化软骨的正下方。它是一层致密、僵硬的皮质骨。在成熟的人类中，它形成一个封闭的帽子，一边支撑软骨，另一边由松质骨支撑。有关原发性骨关节炎病因的未解问题，以及最近在膝关节研究中使用有限元分析的兴趣，表明需要关于软骨下骨作为特定结构实体的力学特性的详细数据。本研究采用扫描声学显微镜(SAM)、外周定量CT(PQCT)和压痕法对膝关节骨关节炎患者胫骨近端软骨下骨和关节软骨的弹性模量值进行了测量。胫骨近端钢板取自骨关节病患者的胫骨。盘状试件从这些钢板上的标准位置用岩心钻头加工。标本的轴线与胫骨长轴平行。用针法测量软骨厚度的分布。以下是通过该实验获得的一个实例结果。内侧髁突中部至后方软骨损伤严重，软骨下骨外露。在内侧髁部，软骨下骨的密度和弹性模数后部高于前部。

The subchondral cortex lies immediately below the thin layer of calcified cartilage. It is a layer dense, stiff, cortical bone. In the mature human, it forms a closed cap supporting the cartilage on one side and supported by the cancellous bone on the other. Unanswered questions regarding the etiology of primary osteoarthritis, as well as the recent interest in the use of finite element analysis in the study of knee joint, suggest a need for detailed data on the mechanical properties of subchondral bone as a specific structural entity. However, only limited information is presently available on mechanical property of subchondral bone because of the lack of appropriate local elastic property measuring method.In this study we measured the elastic modulus of human proximal tibial subchondral bone and articular cartilage in the osteoarthritis of knee joint using the scanning acoustic microscope (SAM), peripheral quantitative computed tomography (pQCT) and the indentation method. Proximal tibial plates were taken from human tibiae of osteoarthrosis joints. Disc-shaped specimens were machined from standardized locations on these plates with a core drill. The axes of the specimens were parallel to the long axis of tibia. The distribution of cartilage thickness was measured by needle method. Following is an example results obtain through this experiment. There is a serious damage on the cartilage from the center to posterior of medial condyle and the subchondral boneis exposed. In the medial condyle, the density and the elastic modulus of the subchondral bone is higher at posterior area than anterior.