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.
New treatments alternatives are important since hormone replacement therapy with estrogen—the standard osteoporosis treatment—has recently been shown to have significant side effects.
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[7]: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.
“It was surprising that the presence of pain predicted the higher than normal joint loads,” says Dr. Wimmer. “We thought that the presence of structural changes would have been the indicator that something was seriously wrong with the knee joints.”
Dr. Wimmer says that his group’s work highlights the importance of knee joint alignment and mechanical loading. “Mechanical loading may be even more important than radiographic disease state in determining who is likely to progress to moderate and severe stages of disease.”
The presence of pain related to structural changes in the knee calls for a biomechanical intervention, and while it might seem intuitive to strengthen the knee muscles, this strategy only reduces pain; excess medial compartment loading still occurs.
“Presently non-surgical interventions for knee OA are directed towards alleviating knee pain but no conservative intervention exists that can significantly and reliably affect biomechanical risk factors for progression of knee OA,” says Dr. Wimmer. That’s why they considered an alternative.
Since the hip muscles control the body’s relative center of gravity, they also indirectly dictate balanced movement at the knee. Consequently, Dr. Wimmer and colleagues decided to pilot a novel exercise regimen directed at strengthening the hip abductor muscles.
They enrolled six OA patients with knee disease and strengthened their hip muscles for four weeks.
“The idea was that the patients improve their upper body position during gait and thus lower their knee adduction moments,” says Dr. Wimmer. The treatment seemed to work; all patients reduced their knee adduction moments and also experienced pain relief.
Dr. Wimmer presented details on this trial at the ACR/ARHP Annual Scientific Meeting in November.
Megan White is a medical journalist based in Boston.
