As If Hot Flashes Were Not Enough

Postmenopausal women taking menopausal hormone therapy (MHT) are significantly less likely to develop symptomatic knee osteoarthritis (OA) compared with those who do not take MHT, according to a recent observational study published online last month.

The researchers analyzed data from 4766 postmenopausal women who participated in the Korea National Health and Nutrition Examination Survey (KNHANES) between 2009 and 2012. They defined MHT as receiving regular hormone medication for at least one year; knee OA was defined according to how the patient felt, as well as what their x-rays looked like.

Breaking down the numbers, the 441 women in the MHT group were 30% less likely to have OA compared with the 4325 women in the non-MHT group, after adjusting for MHT duration, age, obesity, age of onset of menses and menopause, high blood pressure, diabetes, alcohol intake, smoking status, and socioeconomic status.

It cannot be concluded from this observational study that we should now consider hormones the fountain of youth, at least when it comes to your knees—and the chronic pain so many experience due to OA of the knees. And it should be remembered that the American Academy of Family Physicians (AAFP) and the US Preventive Services Task Force (USPSTF) recommend against using MHT in postmenopausal women, as, based on the data available, the harms of estrogen therapy outweigh the benefits. According to the USPSTF, although the use of hormone therapy to prevent chronic conditions in postmenopausal women is associated with some benefits, there are also well-documented harms.

Past and current users of hormone therapy had a lower prevalence of knee joint osteoarthritis, but without a long-term study, this study can only suggest that estrogen taken at menopause may inhibit cartilage damage and reduce knee deterioration seen on x-rays.

The concept of hormones as treatment for chronic pain is nothing new. A study published in 2010 in the journal Arthritis and Rheumatism looked at how sex hormones (estrogen and testosterone) can help people with OA. The researchers found that concentrations of these hormones within the joint can provide some pain relief to those with late-stage OA.

In this earlier study, the researchers focused on chondrogenic progenitor cells (CPCs). These cells are in tissue affected by osteoarthritis, and in theory they can help the tissue regenerate itself; one source of stimulation of these cells is hormone therapy.

Sex hormones are important for more than sex drive; estrogen and testosterone also help with cell growth and maintenance of muscles and bones, for example. Therefore, the researchers wanted to see if sex hormones could make CPCs regenerate joint tissue.

The researchers examined tissue samples from 372 total knee replacement patients, and they found estrogen receptors and testosterone receptors in that tissue. Putting estrogen or testosterone into the tissue cells did increase the regenerative properties of the CPCs—but that was sex-dependent. Tissue from women was most influenced by estrogen; tissue from men was most influenced by testosterone.

A new benefit-risk analysis might be warranted for some patients when it comes to MHT. Another study might explain what that means for the treatment of the pain of knee OA.