Early puberty, giving birth to multiple children, and taking hormone replacement therapy (HRT), all increase a woman's risk of needing joint replacement surgery due to arthritis.
Studies suggest that female sex hormones may play a role in osteoarthritis as women have a higher prevalence of this disorder and the incidence increases at the time of menopause. But few studies have focused on the role of reproductive factors such as age at menarche and menopause, number of children borne, the use of oral contraceptives or hormone replacement therapy.
Researchers from UK studied 1.3 million women recruited in 1996-2001 at an average age of 56 years. During an average follow-up of 6 years, approximately 12,000 women were found to have a hip replaced and 10,000 had a knee replaced. It was found that early menstruation (i.e., younger than 11 years old) increased the likelihood of needing both types of joint surgery by between 9 percent and 15 percent, while every successive birth increased the risk of needing a new hip by 2 percent and a new knee by 8 percent. The age of menopause did not affect the risk.
Although use of oral contraceptives did not impact the risk of joint replacement surgery, current use of HRT raised the odds of hip replacement by 38 percent and of knee replacement by 58 percent, compared with never having used HRT.
Having a high body mass index (BMI) is known to increase the risk of osteoarthritis and joint replacement but it is unlikely that a woman's current BMI would explain the associations found in the study as the researchers adjusted their analyses for this factor.
However, the underlying reasons for these findings remain unclear and further work is needed to understand the role of such potentially modifiable factors.
Annals of the Rheumatic Diseases
October 2008
October 2008