Drug Slows Progression of Knee Osteoarthritis

A drug that is approved in 100 countries but not the USA was the subject of a three-year study of patients with mild to moderate knee osteoarthritis (OA). Patients who took strontium ranelate found that it reduced the structural progression of the disease. Researchers say that this may be the first disease-modifying drug for this condition. The study was reported by Nancy Walsh, staff writer for MedPage Today.

In the study, Jean-Yves Reginster, M.D., of the University of Liège in Belgium, and his colleagues randomized 1, 683 patients with mild-to-moderate knee OA to receive either 1 g or 2 g per day of strontium ranelate. More than two-thirds of the study participants were women with a mean age of 63 years and average disease duration of seven years. All of the participants had symptomatic disease and joint space width in the medial compartment of the knee of 2.5mm to 5mm on radiographic imaging. While both doses were associated with the inhibition of radiographic progression, clinical benefits were seen only for the 2-g dose, which is the dose used in osteoporosis.

The study found significantly less joint space narrowing, showing decreases in joint space width of −0.23mm and −0.27mm, respectively, compared with a loss of −0.37mm in the participants who received a placebo. This represented differences of 0.14mm (P<0.001) for the 1-mg dose and 0.10 (P=0.018) for the 2-g dose. There was with no significant difference between the two doses, Reginster reported in a press briefing at the annual meeting of the American College of Rheumatology.

“The clinical relevance of this is that if you reach a 0.5mm decrease over time in joint space, you have a five-fold increased need for surgery five to ten years later, ” he said. Knee OA is one of the most common debilitating diseases of older individuals, affecting more than 50% of people over 60.

Walsh noted that strontium ranelate has dual actions, in that it concomitantly inhibits bone resorption and stimulates bone formation. It is available in more than 100 countries for the treatment of postmenopausal osteoporosis, though it is not approved by the FDA for use in the U.S.