HRT users more likely to need hip and knee replacement

Using hormone replacement therapy (HRT) and having several children significantly increases the likelihood that a woman will need to undergo joint replacement surgery later on in life, new research suggests.

Dr Bette Liu and colleagues at England's University of Oxford, studied data from 1.3 million women involved in The Million Women Study to determine whether reproductive history or use of oral contraceptives and HRT had any impact upon a woman's risk of joint replacement surgery.

Results showed that women who used HRT were 38% more likely to need a hip replacement and 58% more likely to need a knee replacement than women who had never used HRT. Oral contraceptive use had no effect upon risk of joint replacement.

With regards to reproductive history, starting menstruation before the age of 11 was found to increase the risk of hip joint replacement by 9% and knee joint replacement by 15%. Having children also increased the risk of joint surgery, with each successive birth increasing the risk of hip replacement by 2% and knee replacement by 8%.

“These findings, along with other evidence, strongly suggest that the female sex hormone, estrogen, plays a role in the development of osteoarthritis of the hip and knee and the subsequent need for joint replacement,” said Dr Liu in a news release issued by the University of Oxford. However, she adds: “There is currently not enough evidence to recommend women change their use of HRT because they may be worried about developing osteoarthritis or having a joint replacement.”

Liu B, Balkwill A, Cooper C, Roddam A, Brown A, Beral V. Reproductive history, hormonal factors and the incidence of hip and knee replacement for osteoarthritis in middle-aged women. Ann Rheum Dis. Published Online First: 28 October 2008. doi:10.1136/ard.2008.095653

News release: HRT increases likelihood of hip and knee replacement. University of Oxford. October 28th 2008.