A Colorado State University study of bone loss in female sheep has unveiled a possible treatment for osteoporosis, a debilitating disease that affects 10 million people in the United States.
In a one-year pilot study of 18 adult female sheep, clinical sciences Professor Simon Turner found that bone density in the hind legs of sheep increased when they were regularly exposed to a metal plate emitting a subtle but high-frequency vibration.
Using a method called dual-energy x-ray absorptiometry, bone density measurements were taken at seven areas in each ewe at the beginning of the study and every three months. Half the ewes were constrained in a chute so their hind legs stood on the vibrating plate for 20 minutes a day, five days a week over a one-year period.
The ewes whose hind legs were regularly exposed to the vibrations showed a 3 percent increase in bone density compared with the ewes that did not undergo treatment. Most of the increase in bone density in the sheep subjected to the vibrations occurred in the first six months of the study, then leveled out in the last six months, Turner said.
The Colorado State study–conducted with noted researchers Clint Rubin and Ken McCloud at State University of New York at Stony Brook–points to the possibility of using vibrations in some form as a non-drug treatment for osteoporosis.
Numerous risk factors are related to the development of osteoporosis, including lack of exercise, a diet low in calcium and estrogen deficiency after menopause. Because women can lose up to 20 percent of bone mass in the five to seven years following menopause, doctors often prescribe estrogen replacement therapy to help prevent bone loss and treat other symptoms of menopause. Turner points out that some women are reluctant to take hormones or experience side effects, prompting drug companies to call for effective alternatives.
The vibrating plate appears to mimic the benefits of exercise without subjecting bone to intense strain, Turner said. Subjecting bones to vibrations at high frequencies (such as those used in the study) may be an ideal treatment for older, less active women with osteoporosis.
"These findings are very promising," Turner said. "A three percent increase in bone density may not sound like a lot, but it may be enough to take a person out of the risk zone for fractures. They may still be classified as having osteoporosis, but every little bit of added bone density may help." Results from the pilot study were so promising that the National Institutes of Health has funded a more comprehensive, $1.2 million study over the next four years. Scheduled to begin this month, the study will analyze the effects of different frequencies and durations of exposure on bone density.
The project also will compare the effects of different vibration exposures on ewes with and without ovaries. Ewes without ovaries–which have lower estrogen levels than those with ovaries–will be allowed to lose bone mass for one year before being exposed to vibrations. Researchers are hopeful that the use of vibrations will not only help prevent additional bone loss, but also will prove effective in adding bone.
Turner and his research assistants will conduct all of the testing and experiments on the sheep at Colorado State, while researchers at Stony Brook will be responsible for laboratory and clinical analysis generated from the study "Our hypothesis is that there is a certain frequency and a certain length of exposure that will produce maximum results in terms of increasing bone density," Turner said. "Once we know what that benchmark is, we’ll know more specifically how low intensity, high-frequency vibrations might benefit women with osteoporosis. It isn’t very practical for older women to head to the gym to work out and strengthen bone. These low-intensity vibrations may be an alternative." Turner’s study of sheep over the past several years has proven they are a suitable comparison for investigating the effects of menopause in women. In other research projects, Turner has found that ewes without ovaries mimicked many of the same physiological effects found in post-menopausal women, including bone loss and changes in the makeup of blood vessels. Turner will further pursue the possible link between estrogen deficiency and heart disease–the leading killer of women–in a separate sheep study funded for $74,000 by the National Institutes of Aging.
Turner’s expertise using sheep as a model for post- menopausal osteoporosis led researchers at Stony Brook to form a partnership with Colorado State’s Veterinary Teaching Hospital. In previous studies, Stony Brook had been able to document the benefits of high-frequency vibrations on bone density in the legs of turkeys, but researchers needed a model that was more similar to women with osteoporosis.
Finding alternative treatments for the disease will give physicians and patients more choices in dealing with osteoporosis, a disease characterized by low bone mass and deterioration of bone tissue. According to the National Resource Center for Osteoporosis and Related Bone Diseases, 10 million Americans have osteoporosis and 18 million others have low enough bone mass to place them at risk for the disease. The center says osteoporosis is responsible for 1.5 million hip, spine and wrist fractures annually and $14 billion a year in directly related health care costs.