Osteoporosis drugs falsely implicated in rare thigh bone fractures, say new reports

By Dr. Ananya Mandal, MDMar 25 2010

Osteoporosis is a disease of the bones usually affecting elderly women and causes the bones to become brittle and easily breakable. Since last two years some alarming reports of women on drugs for therapy of this disease have come to notice. These reports show that these drugs intended for therapy may result in rare and serious fractures of their thigh bones where the bones break clean or may splinter. Often these fractures were not associated with any fall or impact. Moreover some of the sufferers are middle aged women in their 50’s who do not have full blown osteoporosis, a condition known as pre-osteoporosis or osteopenia.

These fractures are seen in the long bones of the thigh or femur. They may also occur in the pelvis. These fractures take longer to heal says Dr. Clifford J. Rosen, a professor of medicine at Tufts University School of Medicine. Surgeons may have to insert a long rod in the bone to set it. Patients "just step, they hear a crack, and they suffer a fracture," said Professor Dennis M. Black, who specializes in epidemiology and biostatistics at University of California, San Francisco.

On Wednesday a report was published in the New England Journal of Medicine that said there was no clear association between the drugs – of bisphosphonate class and these rare fractures.

Dr. Black said that thigh bone fractures are really rare. He says that the risk of these fractures outweighs the benefits that these drugs provide in osteoporotic women by prevention hip and spine fractures.

Thighbone fractures “are much much less common than typical hip fractures,” said Dr. Elizabeth Shane, a professor of medicine at the College of Physicians and Surgeons at Columbia University. “While these fractures are devastating, so are the more common types of hip fractures that are prevented by bisphosphonates.”

Dr. Shane went on to say that in women with pre-osteoporosis also known as osteopenia, there is a lower risk of fractures. In these women the risk-benefits analysis of these drugs need to be re-assessed. The rationale for using these drugs in pre-osteoporosis was thought to be protective. But she said that current management guidelines do not recommend therapy of osteopenia patients with bisphosphonates.

The reported study by Dr. Black was undertaken is assistance with Novartis and Merck who make these drugs. 14195 women with osteopenia on bisphosphonates were studied for 10 years.

“We had access to all the data,” Dr. Black said. “So when this issue came up we decided to go through all the hip and thigh fractures.” It was seen that hip fractures in 284 of the women and the unusual thighbone fractures in 10 women, who had a total of 12 such fractures. The number of fractures was so low it was impossible to say if there really was an increased risk with the drugs.

“The point is, these fractures are so rare you can’t say very much about them,” Dr. Black said.

This new study reassures millions of women taking Fosamax and Reclast.

Dr. Black says "If we treated 1,000 osteoporotic women for three years, we estimate you would prevent 100 fractures," at a possible cost of one or fewer of the unusual and rare thigh bone fractures examined in this study.