Osteoarthritis - histology and pathogenetic concepts

Osteoarthritis is the most common joint disease affecting over 60% of the e lderly population. It is characterized by the progressive erosion of articu lar cartilage leading to incapacity of movement. In the great majority of i nstances, osteoarthritis appears insidiously, without apparent initiating c ause. This primary form is usually oligoarticular involving hip, knee, cerv ical vertebrae, interphalangeal joints of the fingers or tarsometatarsal jo ints of the feet. In case of an underlying systemic disease or local injury the cartilage destruction is considered as secondary osteoarthritis. The p athogenesis of primary osteoarthritis suggests an intrinsic disease of cart ilage in which biochemical and metabolic alterations result in its breakdow n. Within the last decades different models were established which also con centrated on other joint structures such as bone or ligaments. Changes of t he subchondral bone were found to precide cartilage damage suggesting a pri mary alteration of the subchondral region. Other studies concentrated on th e metabolic activity of chondrocytes in healthy cartilage of osteoarthritis patients. The precise event that leads to these changes is still not clear . This review concentrates on the histological features in the course of th e disease and tries to provide a summary on different pathogenetic concepts .