African-American women have the highest risk of developing knee osteoarthritis (OA) and needing joint replacement surgery, according to a study recently presented at the 2012 annual meeting of the American College of Rheumatology. The research, which looked at the lifetime risk of knee OA for different segments of society, also found that Hispanic women have higher rates than Caucasian women and than men of all races.

Knee OA occurs when the cartilage that cushions the joint wears away. It is painful, can interfere with daily tasks, and has no “cure” – aside from total knee replacement surgery.

Elena Losina, PhD, associate professor of orthopaedics at Harvard Medical School in Boston, wanted to identify who is most at risk of developing knee OA and when. She and her colleagues turned to a computer simulation model and entered information from published OA studies. The model then estimated the risk of developing knee OA, at different time points, for African-American men and women, Hispanic men and women, and Caucasian men and women.

The model shows that among people age 40 without existing arthritis, the highest lifetime risk of developing painful knee OA is in African-American women (17 percent) and the lowest was in Caucasian men (10 percent). By age 65, 11.3 percent of African-American women, 10.5 percent of Hispanic women and 10 percent of Caucasian women are expected to develop painful knee OA. Total knee replacement is expected to be needed in 6.8 percent of African-American women but in only 3.8 percent of Hispanic men.

Losina says that much of the higher risk among African-American and Hispanic women is due to their higher rates being overweight or obese, a major risk factor for developing knee OA, particularly in women. Weight loss, exercise and a healthy diet can reduce this risk, she says.

“We know that obesity increases the risk of osteoarthritis, and weight loss is likely to lower the risk of osteoarthritis and the need for total knee replacement surgery,” says Losina.

Losina says she and her co-authors hope that their study will lead to better and more targeted care for African-American and Hispanic women, including improved education about factors they can change to reduce their risk of developing knee OA.

In addition to maintaining a healthy weight and exercising regularly, Losina says that young people who engage in sports need to learn the right way to exercise to prevent knee injury – which can lead to OA down the road. Specific exercises that help prevent strain injuries (sometimes called ergonomic exercises) and stretching are helpful, as is not going to extremes by exercising vigorously for too many hours a day.

“This study emphasizes the importance of lifestyle modifications that may be able to reduce the risk of this common and painful disease, as well as the risk of having to undergo total knee replacement surgery,” says Amanda Nelson, MD, an assistant professor of medicine at the University of North Carolina Thurston Arthritis Research Center in Chapel Hill. Dr. Nelson was not involved in the study.