Almost half in U.S. will get knee arthritis: study

WASHINGTON (Reuters) - Nearly half of U.S. adults will develop painful arthritis of the knee, a leading cause of disability, and hospitalizations for the condition are soaring, researchers reported on Wednesday.

During their lifetimes, an estimated 45 percent of Americans will develop knee osteoarthritis, a common kind of arthritis that wears away cartilage cushioning the knee joint, according to a study in the journal Arthritis Care & Research.

U.S. Centers for Disease Control and Prevention and University of North Carolina researchers based the findings on data from 3,068 people age 45 and older in North Carolina.

Obese people had a higher risk, with the extra weight putting additional stress on the knee joint. While 35 percent of normal-weight people got osteoarthritis of the knee, 65 percent of obese people developed it, along with 44 percent of overweight people, the researchers said.

"Simply put, people who keep their weight within the normal range are much less likely to develop symptomatic knee osteoarthritis as they get older, and thus much less likely to face the need for major surgical procedures such as knee replacement surgery," Dr. Joanne Jordan of the University of North Carolina, one of the researchers, said in a statement.

There were no significant differences in risk associated with sex, race or education level, the researchers said.

The people in the study were interviewed and were given an exam that included X-ray images of their knees.

In addition, a report by an agency of the U.S. Department of Health and Human Services showed that hospitalizations due to osteoarthritis rose to 735,000 in 2006 from 322,000 in 1993, mostly due to an increase in knee replacement operations.

From 2000 to 2006, knee replacement surgery rates rose 65 percent, while hip replacement surgery rates rose 21 percent, according to the Agency for Healthcare Research and Quality.

Osteoarthritis, also called degenerative joint disease, is the most common type of arthritis. It can affect any joint but most often affects the hands, hips, knees and spine.

It worsens over time and there is no cure. The pain can be disabling and doctors may recommend joint replacement surgery.

(Reporting by Will Dunham; Editing by Maggie Fox and John O'Callaghan)

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