It usually begins in people over the age of 60, but it may occur at an earlier age. Osteoarthritis progresses slowly. It may begin with minor trauma or repeated injury to the joint. The joint enlarges and movement becomes limited. The cartilage breaks down first.
Cartilage is the joint's cushion that covers the ends of bones allowing free movement.
It becomes rough, frays, or wears away, leaving bones to grind against each other. As a result, the joint becomes irritated and inflamed. Sometimes the irritation causes abnormal bone growths, known as spurs, that increase swelling. The disease normally affects the feet, knees, hips, and fingers. Usually only one, or maybe a few, joints are affected at one time.