HRT May Make Joint Replacement More LikelyOct 28, 2008 | Parker Waichman LLP
Women taking hormone replacement therapy—HRT—are likelier to require joint surgery, according to researchers at Oxford University. Women taking HRT experienced a 58 percent greater risk of needing a new knee versus women who had never used HRT; the women’s chances of requiring a hip replacement were 38 percent higher if they were taking HRT. HRT drugs link Premarin and Prempro are used to treat menopause symptoms.
The findings are a bit surprising because HRT is a popular preventative measure for osteoporosis, thinning of the bones. The Oxford team said that while the results are baffling, they may be due to the effect of the oestrogen in HRT on the joints. Meanwhile, other experts challenged the findings, noting that separate research on HRT shows it improves joint elasticity. The research team believes HRT probably enables women to stay fitter for longer, resulting in greater demand for joint replacements as compared with their more sedentary counterparts. The newest findings were published today in the journal Annals of the Rheumatic Diseases and are the result of a survey of 1.3 million middle-aged British women.
As part of the survey, the researchers asked women how old they were when they had their first and last periods, how many children they had given birth to, and whether they had used oral contraceptives and HRT. The women were monitored for about six years to determine if they were admitted to a hospital for a knee or hip replacement for the joint disease osteoarthritis. In the period studied, over 12,000 women required a hip replacement; slightly less than 10,000 required a knee replacement. Those women who gave birth to a lot of children and who experienced puberty early also showed a higher chance of requiring joint replacement. Onset of menstruation at or before age 11 increased the probability of both types of replacement surgery by between nine and 15 percent. Another increasing factor for replacement surgery was each birth—for hips, by two percent per child and for knees by eight percent per child. Although oral contraceptives do supply the body with additional oestrogen, previous use had no affect on the need for joint surgery.
Researcher Dr. Bette Liu said, “These findings, along with other evidence, strongly suggest that the female sex hormone oestrogen plays a role in the development of osteoarthritis of the hip and knee and the subsequent need for joint replacement.” Many experts feel that women taking HRT are better off and better educated and could be receiving joint replacements because they make more use of health services.
Dr. Liu noted that, ‘There is not enough evidence to recommend women change their use of HRT because they may be worried about developing osteoarthritis or having a joint replacement.” Meanwhile, Dr. John Stevenson, chairman of the charity Women's Health Concern, pointed out that previous studies using MRI scans found HRT users had more cartilage in knee joints than non-users, which would help prevent osteoarthritis. “There is no plausible biological reason for this finding when we know oestrogen protects bones,” he added. “If it's correct then it may demonstrate that women on HRT who tend to be more active may eventually need a replacement as a result of more wear and tear, especially as they tend to live longer than women not taking HRT.”