Arthritis

The prevalence of arthritis (chronic damage of the joints) increases with age because the most common form, osteoarthritis, is age related, and also because chronic arthritis, particularly rheumatoid arthritis, persists into old age even when starting in early adult life (Silman and Hoch-berg). Osteoarthritis and rheumatoid arthritis are common, and represent two distinct but related mechanisms of joint disease in old age: respectively, "wear and tear" and inflammation.

The clinical features of arthritis. Pain is the predominant symptom. Most pronounced on movement, it also occurs at rest, after exercise, and at night. The other main complaint is stiffness, occurring in the morning and after exercise, when it is termed "gelling." In inflammatory arthritis, morning stiffness exceeds thirty minutes. Joint swelling is common, due to synovitis (inflammation of the joint lining), synovial effusions (swelling due to fluid in the joint cavity), and bony swelling around joints. Crepitus, grating when joints are moved, characterizes osteoarthritis. Arthritis causes muscle weakness that may be profound. Finally, there may be loss of movement due to joint swelling, muscle weakness, and deformities when joints are damaged.

The effects of arthritis. Arthritis causes disability and impairs quality of life due to the direct effect of inflammation of the synovium (synovitis). The pain, inflammation, and joint destruction of synovitis are compounded by muscle weakness and decreased sense of joint (proprioception) (British League Against Rheumatism).