What is osteoarthritis (OA)?

Updated: Oct 12, 2020
  • Author: Carlos J Lozada, MD; Chief Editor: Herbert S Diamond, MD  more...
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Osteoarthritis is the most common type of joint disease, affecting more than 30 million individuals in the United States alone. [1] It is the leading cause of chronic disability in older adults, costing the US greater than $185 billion annually. [2]   It can be thought of as primarily a  degenerative disorder with inflammatory components arising from the biochemical breakdown of articular (hyaline) cartilage in the synovial joints. The current view holds that osteoarthritis involves not only the articular cartilage but the entire joint organ, including the subchondral bone and synovium. (See the image below.)

Anteroposterior (AP) radiograph of the hip reveals Anteroposterior (AP) radiograph of the hip reveals severe superior migration of the femoral head (which reflects loss of articular cartilage), subchondral sclerosis, prominent osteophytes, and a large Egger cyst in the superior acetabulum. Mild flattening of the superior aspect of the femoral head is present.

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