Study on the microstructure of human articular cartilage/bone interface

For improving the theory of gradient microstructure of cartilage/bone interface, human distal femurs were studied. Scanning Electron Microscope (SEM), histological sections and MicroCT were used to observe, measure and model the microstructure of cartilage/bone interface. The results showed that the cartilage/bone interface is in a hierarchical structure which is composed of four different tissue layers. The interlocking of hyaline cartilage and calcified cartilage and that of calcified cartilage and subchondral bone are in the manner of " protrusion-pore" with average diameter of 17.0 μm and 34.1 μm respectively. In addition, the cancellous bone under the cartilage is also formed by four layer hierarchical structure, and the adjacent layers are connected by bone trabecula in the shape of H, I and Y, forming a complex interwoven network structure. Finally, the simplified structure model of the cartilage/bone interface was proposed according to the natural articular cartilage/bone interface. The simplified model is a 4-layer gradient biomimetic structure, which corresponds to four different tissues of natural cartilage/bone interface. The results of this work would be beneficial to the design of bionic scaffold for the tissue engineering of articular cartilage/bone.