According to research presented this week at the American College of Rheumatology Annual Meeting in Washington, D.C., a daily dose of strontium ranelate -- a medication prescribed for osteoporosis -- may delay knee osteoarthritis progression. The study also revealed that taking strontium ranelate may improve knee pain, reduce joint damage and the need for surgery.

Knee osteoarthritis is caused by cartilage breakdown in the knee joint. Factors that increase the risk of knee osteoarthritis include obesity, age, prior injury to the knee, extreme stress to the joints, and family history. In 2005, 27 million Americans suffered from osteoarthritis, and one in two people will have symptomatic knee arthritis by age 85.

Strontium ranelate is an osteoporosis treatment proven to prevent vertebral and hip fractures. In non-clinical studies, strontium ranelate was shown to stimulate bone mass by slowing the breakdown of bone and stimulating new bone growth, having a positive effect on cartilage. Current OA treatments focus on improving disease symptoms through a combination of medication and non-pharmaceutical therapy, but there is currently no treatment approved to delay the progression of the disease. An international group of researchers recently evaluated if strontium ranelate was effective in reducing joint damage and symptoms caused by knee OA.

"Osteoarthritis is the most common disease in the elderly and there are currently major unmet medical needs in OA disease management," says Jean-Yves Reginster, MD, PhD, lead investigator in the study and president and chair, department of public health sciences at the University of Liège in Belgium. "There is currently no medication, approved by regulatory authorities to prevent the structural progression of the disease."

The Strontium Ranelate Knee Osteoarthritis Trial (also called SEKOIA) studied 1,683 participants with symptomatic primary knee OA over a three-year period. Participants were divided into three groups and randomly selected to receive strontium ranelate or placebo. Participants given strontium ranelate received one or two gram(s) daily dosage. Joint damage was evaluated yearly using digital X-rays. Also, using a computer assisted method, researchers measured knee joint space width, which correlates with cartilage loss. Researchers also evaluated symptoms such as pain, stiffness and changes in physical function using validated tools such as the WOMAC questionnaire.

Of the 1,683 participants, 82 percent (or 1,371) completed the study. Sixty-nine percent of the participants were female with average age 63 years-old, average body mass index (also called BMI) of 30±5 kg/m2, and average joint space width measuring 3.5 millimeters. Based on a test that measured disease progression, 60 percent of the patients had mild (stage two) and 40 percent moderate (stage three) knee OA.

Researchers noted that strontium ranelate was associated with a decrease in joint damage. After one year, cartilage loss in both groups assessed by the joint space width was -0.23±0.56 mm with 1g/day;-0.27±0.63 mm with 2g/day and -0.37±0.59 mm with placebo. The differences between treatment and placebo groups were 0.14 mm for 1g/day and 0.10 mm for 2g/day. Researchers also noted that strontium ranelate was effective in reducing pain and improving physical function. Overall, treatment with strontium ranelate was well tolerated, with no significant difference in adverse events between both treatment groups and placebo. Additionally, the safety of strontium ranelate was consistent with what was previously observed in osteoporosis.

"Strontium ranelate is a drug approved in 102 countries for the management of post-menopausal osteoporosis, which has been proven to be safe when used for ten years in this particular indication. Results of the present trial show also its ability to reduce the progression of osteoarthritis. This could be a major step in the global management of musculo-skeletal disorders in the elderly subjects," says Dr. Reginster.

Patients should talk to their rheumatologists to determine their best course of treatment.