Stiffness and pain in the joints was for centuries seen as a mark of mortality, one of the natural shocks of old age: just look at Leonardo da Vinci or Thomas Rowlandson's caricatures of old people, with their crooked digits and knobbly joints. Since the 16th century, anatomists have been familiar with the basic structure of joints—bones capped with cartilage, connected by ligaments, and lubricated by synovial fluid—and the name they gave to the principal disorder of these joints is a classic example of plain English put into learned Greek: arthritis, literally joint inflammation. ...physicians increasingly acknowledged a distinction between rheumatoid arthritis as a form of chronic inflammation and osteoarthritis as the consequence of physical wear. A broad demographic shift forced industrial states and their health-care systems to confront the burden of chronic disease affecting older populations, while medicine itself took on a new role in monitoring and maintaining health from cradle to grave.