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Stories for Reprint
Men Under 55 at Greater Risk of Knee Arthritis
By Ferdous Al-Faruque, MARRTC Staff
A new study by the Arthritis Institute of America has found that gender and body fat may be indicators of who gets knee osteoarthritis in people under 55. Osteoarthritis, or OA, happens when cartilage that covers the end of a bone in the joint wears away, which can lead to pain and disability.
The study found men under age 55 were 85 percent more likely to develop OA and people who were obese were over three times more likely to develop the condition. Participants in the study were between the ages of 40 and 54. They completed questionnaires about their health and were given periodic knee x-rays over several years. More than 70 percent of the 633 participants were women.
Frances Vaughn Wilder, PhD, executive director of the Arthritis Research Institute of America and principal investigator of the study, says several factors may explain their findings. Weight seems to be a common factor when it comes to knee OA. More body mass means a higher weight load is put on the knee says Wilder. "And that increases the likelihood of bone-on-bone contact allowing damage to the surrounding cartilage." In a related study, researchers found overweight people age 40 and older with knee OA were twice as likely to have knee pain and extremely obese people were nine times more likely.
The factors for the gender difference in knee OA are not as simple or clear. First, women under age 55 may benefit from the protective effect estrogen has on bones, which can reduce osteoarthritis according to Wilder. "Clearly most women (younger than 55) are in the pre-menopausal state where they have estrogen (in their blood)," she says. "That may put them at lower risk (of developing knee OA)." Wilder says that after menopause women produce less estrogen, which may explain why women are at greater risk of developing the disease after 55.
The research concentrated on who got knee OA rather than why they got it. However, Wilder says in addition to the suggested protective effect of estrogen, which may explain why fewer women below 55 get knee OA, past injury to the knee may also explain why more men get the disease. In previous research Wilder has found that knee injury was an important indicator for knee OA and that men may be more prone to such injuries.
According to Wilder this research is a sign to doctors that they need to pay special attention to patients who may be at greater risk of developing knee OA. She says doctors need to evaluate patients for the disease and offer advice on how to reduce the risk.
Exercise and weight loss are be two ways to reduce the risk or even improve the symptoms of knee OA. One study found even a small amount of weight loss could be more effective in reducing knee pain than the best painkillers on the market. Furthermore, weight loss has also shown to help people with knee OA improve their mobility and their overall health.
Today, almost 21 million Americans are estimated to have osteoarthritis. Though it can affect people of all ages, OA is most common in older adults.
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