Osteoarthritis is a form of arthritis that features the breakdown and eventual loss of the cartilage of one or more joints. Cartilage is a protein substance that serves as a “cushion” between the bones of the joints. Among the over 100 different types of arthritis conditions, osteoarthritis is the most common joint disease. OA occurs more frequently as we age. Before age 45, osteoarthritis occurs more frequently in males. After 55 years of age, it occurs more frequently in females. In the United States, all races appear equally affected. A higher incidence of osteoarthritis exists in the Japanese population, while South-African blacks, East Indians, and Southern Chinese have lower rates. Osteoarthritis is abbreviated as OA or referred to as degenerative arthritis or degenerative joint disease (DJD).
Osteoarthritis commonly affects the hands, feet, spine, and large weight-bearing joints, such as the hips and knees. Osteoarthritis usually has no known cause and is referred to as primary osteoarthritis. When the cause of the osteoarthritis is known, the condition is referred to as secondary OA.