Disorder of a joint associated with degeneration of the articular cartilage and subchondral bone and the development of periostal new bone. The disorder is due to a discrepancy between the mechanical demands on the joint (stress, loading, etc.) and its physical resilience. Symptoms include pain, stiffness (reduced flexibility), heat and effusion of the joint. As the disorder is progressive in nature, most of these changes are permanent and the only form of treatment is to reduce pain with anti-inflammatory drugs and to prevent further development.