Nov. 12, 2012 -- A drug used outside the U.S. to treat osteoporosis may not only lessen the everyday pain associated with kneeosteoarthritis, but may even slow down the progression of osteoarthritis, researchers say.
The drug is called strontium ranelate.
In a three-year study of more than 1,300 people with knee osteoarthritis, digital X-rays revealed substantially less loss of cartilage in the joint space in those who took strontium ranelate every day compared with people who took a placebo daily.
In people with osteoarthritis, the cartilage in a joint wears away in some areas. The function of cartilage is to reduce friction in the joints and serve as a "shock absorber." The wearing away of cartilage leads to pain and other symptoms.
Nearly one in 100 people have evidence of knee osteoarthritis on an X-ray. And nearly 19% of women and 14% of men age 45 and older have joint pain, stiffness, and other symptoms of knee osteoarthritis, according to a large 2007 study.
Study head Jean-Yves Reginster, MD, PhD, presented the findings today at the American College of Rheumatology (ACR) Annual Meeting in Washington, D.C. He is president and chair of the department of public health sciences at the University of Liège in Belgium.
Strontium is a trace element found in seawater and soil. Its main dietary sources are:
In several European countries and Australia, a form of strontium, called Protelos (strontium ranelate), is available as a prescription drug for osteoporosis treatment.
Protelos is not approved in the U.S. But forms of the element, such as strontium citrate, are widely available as nutritional supplements in supermarkets, health food stores, and online.
But strontium supplements can't just be substituted for Protelos, says ACR spokesman Stanley Cohen, MD, a rheumatologist at the University of Texas Southwestern Medical School in Dallas. They would have to be tested in another study.
But finding a drug that can actually delay the progression of knee osteoarthritis is difficult, he says. Several large trials of drugs that looked promising in early research failed to pan out.
"That makes this study potentially very exciting," he says.
But until the research has been reviewed by other doctors and published in a medical journal, it is too soon to draw firm conclusions, Cohen says.
With no approved treatment to delay the progression of the disease, current osteoarthritis treatments focus on improving disease symptoms through a combination of medication, physical therapy, and other non-pharmaceutical therapy.