OSTEOARTHRITIS: PATHOGENESIS AND

THE term 'osteoarthritis ' was first introduced by Sir Archibald E. Garrod in the 1890s. In 1909, Nichols and Richardson (1) distinguished, on the basis of anatomical features, the two major categories of chronic arthritis by separating inflammatory arthritis from degenerative arthritis: 'These joint lesions can be divided with great definiteness into two pathological groups: (i) those which arise from primary proliferative changes in the joints, chiefly in the synovial membrane and in the perichondrium, and (ii) those which arise primarily as a degeneration of the joint cartilage... These two pathological groups are characterised by distinct gross and histological differences. ' Nichols and Richardson went on to state that 'the earliest change to be observed in hypertrophic arthritis is a roughening of the cartilage, which begins near the center of the articular surface, i.e. at the point where pressure and friction between the ends of the bones is greatest.' In 1942, Bennett et al. (2) reported on age changes in each decade occurring in the knee joint. They concluded that the earliest changes were to be found in 'those areas in which weight bearing is pre-eminently concentrated, and which are the most severely subjected to shearing and twisting types of stress (... exposed portions of the tibia