THURSDAY, Nov. 4, 2004 (HealthDayNews) -- Drugs used to treat osteoporosis may also help prevent the bone abnormalities that can lead to arthritis of the knee, new research suggests.
The study appears in the November issue of Arthritis & Rheumatism.
A team led by Dr. Laura Carbone, director of the metabolic bone unit at the University of Tennessee Health Science Center, evaluated 818 women, average age 75, enrolled in the Health, Aging, and Body Composition Study, a long-term look at factors contributing to disability. The ongoing research is being conducted at the University of Tennessee and the University of Pittsburgh.
"Women taking estrogen and alendronate had less MRI [magnetic resonance imaging] changes of severe osteoarthritis of the knee," Carbone said.
Osteoarthritis of the knee is one of the five leading causes of disability in older men and women, according to the American Academy of Orthopaedic Surgeons. The risk of disability from knee arthritis is as great as that from heart disease. Arthritis in the knee usually happens in joints that have been injured, infected or traumatized.
In the study, 214 women were taking either estrogen or alendronate (Fosamax) to prevent osteoporotic fractures. Fewer than 10 were taking raloxifene (Evista), another popular osteoporosis drug, but it was not associated with any changes in knee arthritis or its symptoms.
Other drugs are available to prevent fractures, Carbone said, including risedronate (Actonel) and calcitonin spray. However, estrogen and Fosamax happened to be the ones most of the women in the study used.
When Carbone's team looked at the MRI results, women taking Fosamax or estrogen had significantly fewer bone abnormalities associated with severe knee arthritis than those not taking these medicines.
"Some [other] studies have looked at estrogen and osteoarthritis," Carbone said. "Some have shown an effect, and some have not."
Women taking Fosamax also had less knee pain than nonusers. "It's not like a painkiller," Carbone said. "But, long term, they may have less severe changes of osteoarthritis of the knee."
Exactly how do the osteoporosis drugs work? "What we think is, they stop bone from being broken down. If you decrease bone breakdown, then hopefully the osteoarthritis won't be as severe," Carbone said.
In the United States, Carbone said, about 1.5 million osteoporosis-related fractures occur each year. And osteoarthritis, also called "wear-and-tear" arthritis, is the most common type.
Another expert, Dr. Peter Bonutti, an orthopedic surgeon who performs knee replacements, said the study is interesting. "If we can thicken the bone, maybe we can alter the arthritic changes," he said.
The type of bone that benefited from the osteoporosis drugs in the study, called the subchondral plate, lies under cartilage, Bonutti said. It's subject to stress fractures, and once that occurs, pain can start.
It's too early to suggest that women take the bone-building drugs to slow the progression of arthritis, Carbone said. "But if you happen to have to take one of these drugs for osteoporosis, it may have some beneficial effect on osteoarthritis of the knee."
Carbone added she would like to do a longitudinal study in which she follows people over time, assigning some to take the drugs and some not. "This study is a cross-sectional study, one snapshot in time," she said.
Carbone has served as a paid consultant to several makers of arthritis drugs, including Fosamax and Evista.
More information
To learn more about osteoarthritis of the knee, visit the American Academy of Orthopaedic Surgeons.
