Primary Osteoarthritis: What Is It?

What are your chances of getting arthritis of the hip? In the United States, three to six of every 100 Caucasians have a form of hip arthritis called osteoarthritis (OA).

This type of arthritis occurs when the lining of the joints wears away. When this happens, the bones have no cushion and rub together. This damages the joint surfaces even more. The hip and the knee are most commonly affected.

Sometimes people get OA because of another condition that’s already present. A hip condition present at birth called hip dysplasia (shallow hip socket), rheumatoid arthritis in childhood, or any other infection or injury can lead to OA. The term secondary OA is used to describe OA from one of these conditions. When OA is present without a known cause, it is called primary OA.

Researchers are keeping track of how many people develop primary OA. By studying these people, it may be possible to tell who is more likely to have primary OA. Family studies from Sweden, Britain, and the United States show higher rates of hip OA in first-degree relatives (parents or siblings). Very few Black, Asian, or Hispanic people have hip OA. People from Japan and Hong Kong have almost no primary OA of the hip, but they do have more OA of the knee.

People who develop primary OA probably have genetic (inherited) factors present. If you are white and have a mother, father, sister, or brother with primary OA, your chances of getting primary OA are increased.