How are joint pain and stiffness related to arthritis?
In osteoarthritis (OA), the soft, movement-easing cartilage at the ends of joint bones breaks down and wears away as the person grows older. Eventually the bones rub directly against each other whenever the joint moves, causing pain and stiffness. The rest of the body’s joint surfaces are covered with a smooth tissue lining called the synovium: In rheumatoid arthritis (RA), chemical changes in the synovium cause it to destroy cartilage. In post-traumatic arthritis, joint pain and stiffness may develop after injury to the joint; the resulting failure of the bone and cartilage to heal properly causes the roughened joint surfaces to grind together.
