September 2008 ASBMR Meeting: Dr. Abrahamsen Asserts Atypical Fractures Of Femur Are Not Triggered By Fosamax

(Posted by Tom Lamb at DrugInjuryWatch.com)

In late June 2008 we learned that one type of femoral stress fracture (simple, transverse) may be caused by long term use of the popular bisphosphonate Fosamax.  Drs. Dean G. Lorich and Joseph M. Lane of NewYork-Presbyterian Hospital/Weill Cornell Medical Center presented information about this possible new Fosamax side effect in the latest issue of the Journal of Orthopaedic Trauma.

About three months later, however, a Danish researcher said said that such atypical fractures of the femur do not appear to be triggered by Fosamax (alendronate).

In more detail, in mid-September 2008 at the American Society for Bone and Mineral Research (ASBMR) meeting in Montreal, Bo Abrahamsen, Ph.D., of Copenhagen University Hospital Gentofte, asserted that patients treated with the anti-osteoporosis drug Fosamax apparently had a higher risk of these atypical fractures (as well as fractures of any kind) to start with for the simple reason that they were taking a drug known to reduce the risk of hip fractures.

For elaboration on Dr. Abrahamsen's position we turn to the September 15, 2008 Medpage Today article, "ASBMR: Alendronate Exonerated in 'Atypical' Femoral Fractures":

The three case reports earlier this year suggested that a common factor in patients with subtrochanteric or proximal diaphyseal fractures of the femur is [Fosamax]use, Dr. Abrahamsen said.

But those reports did not have any comparison data, he said. "The real problem is the denominator — you don't know how common this is," he said.

It's especially important to know how common such fractures are in comparison with hip fractures, Dr. Abrahamsen said, in order to understand the risks and benefits of the treatment.

To help fill the gap, he and colleagues looked at registry data for all patients born 1945 or earlier who arrived at Danish hospitals with fractures from 1996 through 2005….

He concluded that the atypical fractures are "best classified" as osteoporotic fractures and added that there's no evidence that use of [Fosamax] increases the risk of the atypical broken bones.

More facts in support of Dr. Abrahamsen's position can be found in the primary source for his September 2008 ASBMR presentation, "Subtrochanteric And Diaphyseal Femur Fractures in Patients Treated with Alendronate: A Register-Based National Cohort Study", by Abrahamsen B, et al, which was published in Journal of Bone Mineral Research (JBMR 2008; 23: Abstract 1026).