Osteoarthritis: The Facts
Who develops osteoarthritis?
Osteoarthritis is seen in both females and males in a 3:2 female/male ratio. Occurrence is usually noted between the ages of 45-90, and affects more than 20.7 million Americans today.
What exactly is osteoarthritis?
Osteoarthritis is the type of arthritis involving the cartilage of a joint. The cartilage of a joint is a tough, gristle-like material which is found on the ends of the bones. It forms the surface of the joint on either side. Cartilage is durable and somewhat elastic. It does not have a blood supply and therefore gets its oxygen from the joint fluid surrounding it.
When you use a joint, fluid and waste products are removed from the cartilage by the pressure involved. When pressure is relieved, oxygen and other nutrients are returned to the cartilage. Cartilage also has no nerve supply. It is this characteristic that allows large forces to be transferred without pain.
Over time, the cartilage may become worn. The bony surface of the joint may begin to grate against the bone on the other side and the elasticity of the cartilage may be decreased. Eventually the cartilage may wear away entirely. This cartilage deterioration is, in fact, what defines osteoarthritis. Unlike some other types of arthritis, OA does not affect the whole body. However, the changes which it can cause may limit patients due to pain and loss of movement.
Where does OA occur?
OA can occur in any joint and may occur only on one side of the joint. Usually, it is seen in the joints of the fingers, spine, hips, and knees. These joints fall into three common types of osteoarthritis.1
The first and usually mildest is the OA which affects the hands, causing knobby enlargement of the finger joints. When this occurs at the end joints of the fingers, these enlargements are called Heberden’s nodes. Growths in the middle of the fingers are called Bouchard’s nodes. This type of OA may cause stiffness and changes in the cosmetic appearance of the hand.
The second type of OA involves the spine. This can involve the neck area as well as the back. Bone spurs are symptoms of arthritis not necessarily the cause of pain.
The third type of OA commonly seen involves the weight-bearing joints, most frequently the hips and knees. This form of OA can become quite severe and limiting, or may only periodically cause symptoms. In extreme cases, walking may become extremely difficult or impossible. This type of OA frequently involves both sides of the body, and may cause a deformity in the lower extremity due to the degeneration process.
View our videos on Osteoarthritis of the Hip and Knee below to learn more.
When does OA occur?
OA can develop as a natural process of aging or it may occur as a result of a traumatic injury such as a fracture. Patients who have a congenital malformation of a joint also tend to develop OA at an earlier age than normally seen.
A common idea in past years was that osteoarthritis developed because of “wear and tear” or over-use of a joint. Research studies of people who participate in strenuous activities have failed to show a relationship between these activities and the development of arthritis.
Furthermore, most experts agree that a patient, even when diagnosed with OA, needs to continue a program of exercise to maintain optimal function of the joint.
Why does OA occur?
No one knows for sure what causes osteoarthritis. Some experts believe that people are born with defective cartilage or abnormalities in their joints which lead to the changes seen in OA. Others believe that OA develops as a result of over-using an already injured joint or because of joint damage caused by other arthritic conditions.
Research into the causes, prevention, and treatment of OA as well as other types of arthritis continue to provide improved methods for the relief of symptoms and will continue to aid in the understanding of these disease processes.
- Lorig, K., Fries, P.H., James, F., The Arthritis Helpbook, 4th ed., Addison-Wesley Publishing Co., 1995.