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Link between drugs, broken femur bone studied

​​​​​​​​​​​​Marshfield Clinic researcher has been studying the relationship between a specific type of bone-strengthening drug and an increased risk of a certain kind of break in the thigh bone, or femur.

women exercisingRheumatologist Fergus McKiernan, M.D.​, a long-time Clinic researcher, was appointed to the expert Task Force of the American Society for Bone and Mineral Research. Its goal was to determine if there was an increase in atypical femur fractures in persons taking specific drugs, including alendronate (Fosamax), risedronate (Actonel) and zoledronate (Reclast).

"Atypical" means that the fracture has the following unusual characteristics:

  • The femur break is at the shaft rather than closer to the hip joint
  • It occurs after minimal or no trauma (such as a fall from standing height)
  • It has a specific X-ray appearance

The task force findings, released in 2010 and recently updated, were based on an exhaustive review of published scientific reports, preclinical studies and expert clinical experience. They confirmed an association between these drugs and fractures. However, factors such as a genetic influence, other diseases, medication interaction and duration of drug exposure likely affect this relationship.

Atypical femur fractures have occasionally been seen in people who have never taken these drugs and have no other apparent predisposing risk.

"While there is an association between atypical femur fractures and long-term use of these drugs, that risk appears to be very low," said Dr. McKiernan. The risk appears to increase the longer people take these medications."

"The best evidence continues to indicate that these bone-strengthening drugs prevent many more 'typical' hip fractures than the 'atypical' fractures with which they have been associated."

He noted that these drugs continue to play an important role in fracture prevention, but their use should be reserved for persons at high risk for fracture and used for only a limited period of time.

Dr. McKiernan was the first researcher to demonstrate that atypical femur fractures can sometimes be detected on routine bone mineral density scans. Further research will determine how this information will be used in day-to-day practice.

"Marshfield Clinic was one of the first centers to report the relationship between these specific bone-strengthening drugs and atypical femur fractures, and we continue to look for new ways to prevent and detect these fractures," Dr. McKiernan said.

If you are taking one of these medications, talk to your doctor about what is best in your particular situation.