A University of British Columbia and Vancouver Coastal Health Research Institute study has found that a popular class of osteoporosis drugs nearly triples the risk of developing bone necrosis, a condition that can lead to disfigurement and incapacitating pain.The research is the largest study of bone necrosis and bisphosphonates, a class of drugs used by millions of women worldwide to help prevent bone fractures due to osteoporosis. It is also the first study to explore the link between bone necrosis and specific brands of bisphosphonates, such as Actonel, Didrocal and Fosamax. Researchers found that all three brands had similar outcomes. Bone necrosis, a relatively rare disease diagnosed in approximately 1 in 20,000 people per year, leads to permanent loss of blood supply to the bones. Without adequate blood supply, the bone tissue dies and causes the bone to collapse. The disease primarily affects shoulders, knees and hips at the joints, causing severe pain and immobility.Published online by the Journal of Rheumatology today, the findings follow a recent U.S. Food and Drug Administration alert about bisphosphonates that highlighted the possibility of severe and sometimes incapacitating bone, joint and/or muscle pain in patients taking the drugs. (To view the FDA alert, visit: http://www.fda.gov/cder/drug/infopage/bisphosphonates/default.htm.)