Biomechanics and repair of articular cartilage.

The most important function of the joints relies on excellent lubrication and the uniform distribution of impact loads onto the underlying bones, together with damping effects. In most joint disorders, as the lesion is limited to the joint surface, it becomes necessary to repair the joint surface. In this article, repair with an artificial composite osteochondral device (COD) is reported, as is biological resurfacing with cultured chondrocytes. The COD consists of polyvinyl alcohol (PVA) hydrogel as artificial cartilage and titanium fiber mesh (TFM) as porous artificial bone. PVA solution was impregnated into the pores of TFM by injection molding, and these two materials were bound together by a gelling process to create the COD. The key problem, i.e., to attain quick and firm attachment to the underlying bone, was addressed by creating this COD, in which the TFM interface allows not only firm attachment of the PVA gel but also strong attachment to the joint surface through bony ingrowth. For the purpose of simulating partial hemiarthroplasty for the femoral head, 30 COD prostheses were implanted into canine femoral heads. Histological findings of the acetabular cartilage and synovial membrane, as well as findings of attachment of the prosthesis to bone, were examined for an 18-month period after the operation. No particular pathological changes in acetabular cartilage were found, and firm attachment of the devices to bone was confirmed. These results indicate that the COD could be a very promising joint repair material.