Early Success for New Postmenopausal Osteoporosis Treatment
Investigators at the Sahlgrenska Academy at Göteborg University in Gothenburg, Sweden, discovered a possible new method for treating the osteoporosis associated with postmenopausal RA.
Explore this issueDecember 2007
New treatments alternatives are important since hormone replacement therapy with estrogen—the standard osteoporosis treatment—has recently been shown to have significant side effects.
Investigators began with a well-studied model of post-menopausal RA in mice. They then used raloxifene, a selective estrogen receptor modulator (SERM), to stimulate estrogen-like action.
“Raloxifene has recently been shown to be more efficient than estrogen in preventing some changes occurring in bone after the ovariectomy of mice—representing premenopause in women,” says Caroline Jochems, MD, lead author of the study, published in Arthritis & Rheumatism (2007;56:3261-3270).
After the disease developed in mice, investigators were able to decrease arthritic activity with the drug—as evidenced by lower frequency of the disease and a lower severity score. They were also able to preserve bone architecture.
According to Dr. Jochems, “the method by which raloxifene prevents the progress of arthritis is not fully understood and needs to be further studied. It does not seem to have common anti-inflammatory properties in all conditions, but has been shown to have these effects in arthritis and autoimmune encephalitis.” Raloxifene prevents the progression of osteoporosis by slowing bone turnover; raloxifene increases bone formation and decreases bone resorption.
Dr. Jochems and colleagues were surprised to learn of raloxifene’s very potent anti-arthritic effects; the SERM does not have a subduing effect on disease in mice—known as delayed type hypersensitivity (DTH)—that is used as a simplified model for arthritis.
Plans for clinical trials in humans are being discussed.
Knee Adduction May Be Key to Pain in OA
People with knee osteoarthritis (OA) typically have radiographic evidence, but the reverse is not always true; some patients who undergo radiographic screening positive for knee OA have no symptoms.
Now, researchers have discovered a biomechanical reason for the discrepancy: people who experience pain have significantly higher knee adduction moments. “The higher the knee adduction moment, the more likely one is to progress from mild to moderate to severe forms of the disease,” says Markus Wimmer, PhD, co-author of the study published in Arthritis Care & Research (2007;57:1254-1260).
To understand why people with suspicious radiographs weren’t registering pain, investigators studied the gaits of asymptomatic adults with radiographs indicating mild degeneration at the knee. These people walked in the same manner as people with healthy radiographs. More revealing was the discovery that they had significantly lower knee adduction moments than people with painful symptoms.