Strontium May Spare More OA Knees from Surgery



WASHINGTON – A daily dose of strontium ranelate was associated with a significant delay in joint space narrowing in adults with symptomatic primary knee osteoarthritis, based on data from the phase III Strontium Ranelate Knee Osteoarthritis Trial (SEKOIA).

Strontium renalate currently is not approved in the United States, but it is approved in more than 100 countries for treating osteoporosis, said Dr. Jean-Yves Reginster, who is head of the Center for Investigation in Bone and Articular Cartilage Metabolism at the University of Liège (Belgium).

Data from nonclinical studies have shown that strontium’s bone-building activity has a positive impact on cartilage as well, he noted at the annual meeting of the American College of Rheumatology.

To examine the effectiveness of strontium ranelate on the progression of knee osteoarthritis (OA), Dr. Reginster and his colleagues randomized 1,683 adults with symptomatic primary knee OA to 1 g of strontium ranelate per day (566 patients), 2 g/day (558 patients), or a placebo (559 patients). Complete data were available for 1,371 patients. The average age of the patients was 63 years, and 69% were women.

Overall, treatment with either dose of strontium was associated with a significant delay in the radiographic progression of knee OA, which was assessed by measuring the radiological joint space narrowing (JSN) of the medial tibiofemoral compartment of the knee joint.

After 1 year, joint space width decreased by 0.27 mm in the 2-g/day group, 0.23 mm in the 1-g/day group, and 0.37 mm in the placebo group. The differences between the 2-g/day and 1-g/day groups and the placebo group were 0.10 mm and 0.14 mm, respectively.

Significantly less radiological progression was noted in both strontium groups, compared with the placebo group. The percentage of patients with radiological progression (defined as joint space narrowing of at least 0.5 mm) was 26% in the 2-g/day group, 22% in the 1-g/day group, and 33% in the placebo group.

"The structural effect is translated clinically into a lower number of patients having a radiological progression over thresholds predictive of OA-related surgery," Dr. Reginster said. The findings suggest that strontium ranelate could reduce the need for knee surgery in OA patients, he added.

In addition, significantly more patients in the 2-g/day group exceeded the minimally perceptible clinical improvement (MCPI) threshold, compared with the placebo patients, on subscores of pain, stiffness, and physical function. The percentage of patients in the 1-g/day group above this threshold was not significantly higher than in the placebo group.

No significant differences in adverse events were observed among the three groups, and the incidence of serious adverse events was 17% in all groups.

The study findings also appeared online on Nov. 9 (Ann. Rheum. Dis. 2012 [doi:10.1136/annrheumdis-2012-202231]).

The study was sponsored by Servier. Dr. Reginster disclosed financial relationships with multiple companies, including Servier.

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