Pathology of Osteoarthrosis

Abstract

The pathogenesis of mechanically induced arthrosis is due to a disproportion between the physiological resistance of the supporting tissue and the compressive stress developing in the joint. Those mechanical factors contributing to an increase in articular pressure are (1) a rise in the magnitude of the resultant force during movement, (2) a reduction of the pressure-transmitting articular surface, and (3) an eccentric position of the resultant force. Cluster formation, subchondral bone sclerosis, and osteophyte formation are reparation attempts made in the course of osteoarthrosis. Osteophytes are of chondral osteogenesis and they are subjected to stress by compressive forces. In considering the problem of the etiopathogenesis of osteoarthrosis, STR/lN-mice are included in current investigations because in this arthrosis model there are two different types of osteoarthrosis; one due to a biomechanically-induced instability (patellar luxation) and one due to biochemical changes (absence of keratan sulfate) in the articular cartilage. Polychrome sequential labeling is used to study the dynamics of subchondral bone sclerosis during developing osteoarthrosis in the knee joints of STR/lN-mice. The results indicate that subchondral sclerosis is caused by cartilage lesion, and that even slight changes of hyaline cartilage may initiate proliferation of the subchondral bone.