NEW YORK (Reuters) -- Postmenopausal women who take supplements of the sex hormone estrogen may significantly cut their risk of debilitating osteoarthritis, say researchers.
Led by Dr. Michael Nevitt at the University of California San Francisco, a team studied the effect of estrogen replacement therapy (ERT) on the development of osteoarthritis in the hip joint.
The researchers found a "significantly lower risk of osteoarthritis of the hip in women who are long-term users of estrogen," according to their report, published this week in the Archives of Internal Medicine.
Osteoarthritis is an often painful degenerative bone disease and "accounts for at least 70% of the more than 200,000 total hip and knee replacement surgical procedures that are performed annually in the United States," write the researchers.
Since osteoarthritis occurs more often in women than men, researchers have long thought the condition might be affected by the female hormone estrogen.
As part of the nationwide Study of Osteoporotic Fractures, Nevitt and colleagues looked at the hip x-rays of almost 5,000 postmenopausal white women over 65 years of age, looking for osteoarthritis. They then compared their findings with the women's medical histories.
"Women who were current users of oral estrogens had a 38% lower risk of any osteoarthritis of the hip," the study concludes.
The reduction in risk got higher as the years of ERT continued. During the first 10 years of ERT therapy, a woman taking ERT was found to have a 25% lower chance of developing osteoarthritis than a woman not taking ERT. When ERT was continued beyond 10 years, this number jumped to over 40%.
"Our findings are consistent with a greater reduction in risk with a longer duration of use," comment the study authors.
But the study found that discontinuing ERT can make women as vulnerable to osteoarthritis as those who had never received the therapy at all. "The risk of osteoarthritis of the hip in past users of estrogen was not different from that of those women who never used estrogen," write the authors.
Nevitt's team theorizes that estrogen levels influence the development of cartilage, especially in heavily-used joint areas like the knees and hips. Cartilage is the 'padding' that helps joints move without pain -- when it isn't replaced, joint friction results, and with it comes the pain associated with osteoarthritis. ERT may help ensure that cartilage regeneration continues smoothly.
Although Nevitt's study focused on hip-related illness, a previous study also found a one-third reduction in knee osteoarthritis in postmenopausal women using ERT.
Nevitt says that since "there are no known treatments that can effectively modify the course of osteoarthritis," ERT should be considered as a method of reducing the risk of developing the disease.
SOURCE: Archives of Internal Medicine (1996;156:2073-2080)
