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Estrogen and Your Knees
December 05, 2006
By: Jean Johnson for Knee1
“It’s not very encouraging news to me,” said Lil Anderson of Portland. “First our hormones make us crazy all our lives, and then when they settle down they threaten our very mobility. Think about it. Knee osteoarthritis is what puts old people in wheel chairs.”
|The Center for Human Performance and Joint Restoration in the University of Southern Alabama Health System lists the following as the main focus in current treatment for knee osteoarthritis:|
Steroids or synthetic joint fluid injections
Surgical options include knee arthroscopy or a partial or total joint replacement
Women do put up with a lot from their bodies for the privilege of bearing children. Female hormones, particularly, have sent many on sustained, emotional roller coaster rides for extended periods of their lives. And while declining levels of estrogen might quiet some of the emotional fallout women can experience during their reproductive years, now researchers are saying that low levels of estradiol, a potent type of estrogen, can predispose women to osteoarthritis of the knees.
How Estradiol Functions
Estradiol is central to the growth of secondary sex characteristics like breasts. It is also involved in bone maturation. At menopause, concentrations of estradiol and the other estrogens fall to low levels and cause vascular instability that can bring on hot flashes and night sweats, bone loss or osteoporosis, and increased risk of heart disease.
Now, in addition to heart disease and osteoporosis, new research suggests – as many experts have suspected – that lower estradiol levels can cause knee osteoarthritis.
Who Is At Risk For Osteoarthritis?
As Anderson observed, osteoarthritis is one of the most frequent causes of disability among adults, second only to heart disease. A third of all Americans have evidence of osteoarthritis in the hand, foot, knee, or hip that can be detected via X-ray. Both men and women are diagnosed with the disease, although before age 45, osteoarthritis is more common in men. After 45, women are at greater risk.
With the baby boomer population aging, cases of osteoarthritis are expected to increase. Currently more than 20 million Americans have the disease but by 2030, numbers are expected to triple. Twenty percent of the population, or about 70 million people, will be 65 and older.
According to results published in the August 2006 issue of Arthritis and Rheumatism, women with the lowest levels of estradiol were almost twice as likely to develop osteoarthritis as women with higher levels of this type of estrogen. The study window was three years, a period that Mary Fran Sowers, Ph.D., professor of epidemiology at the University of Michigan in Ann Arbor, said is a relatively short time frame that “may not fully capture the arthritis development process.”
The study included 842 premenopausal and perimenopausal women. Perimenopause is the time during a woman’s forties – or even her thirties – when the body gets ready for menopause. It can last up to six years and be characterized by irregular menstruation, hot flashes, night sweats, mood swings, anxiety, palpitations, depression, insomnia, and vaginal dryness.
For three years, women participating in the study had annual X-rays of their knees as well as blood tests to determine the estradiol and urine levels of two other estrogen metabolites, 2-hydroxyestrone and 16a-hydroxyestrone. According to the American College of Rheumatology, “the results showed that the women who developed knee osteoarthritis during the study period had greater odds of having estradiol concentrations and urinary 2-hydroxyestrone levels in the lowest third of the study population.”
“There has been an ongoing debate as to whether hormone levels contribute to the pathogenesis of osteoarthritis and/or serve as a biomarker of risk for the development of osteoarthritis,” Sowers and her colleagues noted in Arthritis & Rheumatism. “Selected work with animal models provides support for the increased odds of developing osteoarthritis with lower estradiol concentrations.”
On the import of her research, Sowers told CIAOMed that “this is really important because there is a great need to understand the processes associated with the development of osteoarthritis, and this research may open doors to terms of prevention and treatment.”
Sowers added that “We are a long way from treatment and prevention strategies, as this is the first time people have looked at naturally occurring estrogen profiles. Most of the work has been done with hormone replacement therapy.”
Stay tuned for Part Two, where we explore the relationship between knee osteoarthritis and weight, and take a closer look at the condition…
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