arthritis — a family of painful joint disorders. Osteoarthritis, the most common
form, works like this: at the joints, where two bones meet, the bones have a protective layer of
cartilege that protects them. As people age, the cartilege can wear away, leaving unprotected
bones to smash into each other when the joint moves. This hurts!
Rheumatoid arthritis is less common but more serious. It often involves
inflammation. While osteoarthritis
usually occurs later in life, rheumatoid arthritis can strike people of any age.