A study of military service members has found that women serving in the armed forces are at greater risk of hip osteoarthritis (OA) than their male counterparts and that blacks are not genetically protected from the condition, as was previously believed.

Danielle Scher, MD, an orthopedic resident at the William Beaumont Army Medical Center in El Paso, Texas, says anecdotal evidence suggested that hip osteoarthritis affected a large and diverse group of people, including younger adults; but her study set out to prove it.

“Rheumatologists might be seeing this every day but there’s nothing in the literature that was showing real definite numbers,” Dr. Scher says.

Researchers studied information from a military medical database collected from 1998 to 2006 on about 1.5 million service members. They documented 4,262 cases of hip osteoarthritis and then studied the demographics of that group.

What they found was that women in the military had nearly twice the risk of getting hip osteoarthritis when compared to male service members, and that blacks had a 30 percent greater chance of getting hip pain than whites. The risk for hip osteoarthritis also went up with age and with the nature of certain jobs – those assigned to more physically demanding work were more likely to develop hip pain.

The study was published in the April 15, 2009, issue of the journal Arthritis Care & Research.

Joanne Jordan, MD, PhD, of the Thurston Arthritis Research Center at the University of North Carolina in Chapel Hill is running a similar large-scale study called the Johnston County Osteoarthritis Project. She says what she finds interesting about this study is the data regarding race. She says previous data have shown that blacks do not get their hips replaced as often as whites. That led many to believe they were protected from hip osteoarthritis, which this study indicates is not true.

“African Americans are not protected from hip OA,” Dr. Jordan says. “They may not get their hips replaced, but it’s not because they don’t get hip OA. In fact, this study shows they are at an increased risk for hip OA.”

Philip Belmont, Jr., MD, an orthopedic surgeon at the William Beaumont Army Medical Center and a co-author on the study says this is also the first large-scale survey to show a link between activity level and osteoarthritis. That was possible because the rank group in the service indicates how much activity a service member is doing.

He says his work suggests that people “who are construction workers or are farmers who do high-end occupational or agricultural work” should be aware that they are at increased risk of hip osteoarthritis.

Though this is not the first incidence study of hip osteoarthritis, it is the largest to date. And because osteoarthritis has been found to have average direct yearly costs of between $2,650 and $5,700 per person, researchers say their findings are important from a public health standpoint.

“People need to put money and resources toward OA,” Dr. Scher says. “Sometimes I think it’s not looked at as a serious disease, but it really does take up a significant number of health-care dollars. It’s about where we put our resources.”

Dr. Belmont says the Department of Defense has about $60 million directed in the future toward more muscular and skeletal health care for military members and that hip osteoarthritis is an area to which they may need to devote more resources.