About Osteoarthritis of the Knee
Osteoarthritis (OA) is the most common type of arthritis and the most common joint condition, worldwide. In the U.S. alone, more than 21 million people suffer from OA—and more than 14 million of those are estimated to have OA in one or both knees.
In knees with OA, the cartilage protecting the ends of the bones gradually deteriorates, and the joint fluid—called synovial fluid—loses its shock-absorbing qualities. Bones may begin to rub against each other, causing pain, stiffness and loss of movement in the joint. By contrast, a healthy knee’s cartilage and lubricating joint fluid protect and cushion the bones, making moving and bending easy.
The stages of osteoarthritis of the knee
Doctors use two different sets of terminology to talk about the severity of OA. Some may characterize OA as grade 1 to 4 (view the images on the right to learn more). Other doctors may describe OA as mild, moderate or severe.
Mild. The surface of the cartilage in your knee joint begins to wear down. Symptoms are generally mild, and may include occasional pain and brief morning stiffness.
Moderate. Joint cartilage continues to wear away and joint fluid may lose its ability to lubricate and cushion the knee. Bony growths, or spurs, may also form on the edges of the bones. Moving may become more painful.
Severe. Cartilage may totally wear away, causing bones to rub against each other. Pain may be more constant or more severe; your ability to perform day-to-day activities can diminish.
The symptoms of osteoarthritis are treatable, especially in the early stages. If you have pain or stiffness in one or both knees, ask your doctor if you have OA.