Bisphosphonates and Femur Fractures

There's some controversy about the relationship between bisphosphanates and subtrochanteric femoral fractures, very nicely summarized for radiologists by Rogers and Taljanovic in the current issue of the AJR. The take-away point is that even though the FDA's review of the existing data has failed to show a clear connection between bisphosphonate use and atypical subtrochanteric femur fractures, not all existing data was taken into account, and we "should feel comfortable in reporting the association of this type of femoral fracture with long-term bisphosphonate therapy."

Bisphosphonate-related insufficiency fractures are unique and different from the typical osteoporotic insufficiency fractures of the femur we're familiar with. Bisphosphonate-related insufficiency fractures are typically transverse and occur in the proximal third of the femoral diaphysis. They occur in the setting of low-impact trauma, but may also occur spontaneously.

In the case presented here, we have a transverse fracture of the right proximal femoral diaphysis that occurred after minor trauma in a patient on long-term bisphosphonate therapy. If you look carefully at the edge of the film on the left, you can see a small moundlike thickening of the lateral cortex of the subtrochanteric left proximal femur (small pink arrow), better demonstrated on dedicated images of the left femur (large pink arrow). The inset zooms in on the mound, and reveals a horizontally oriented lucency through the mound if you squint hard enough (small blue arrow).

Update

On October 13, 2010 the FDA updated the public regarding the previously communicated information. "As of this notice, the FDA is notifying patients and healthcare professionals of new Warnings and Precautions information that is being added regarding this risk to the labels of all bisphosphonate products approved for the prevention or treatment of osteoporosis. A new Limitations of Use statement will describe the uncertainty of the optimal duration of use of bisphosphonates for the treatment and/or prevention of osteoporosis. In addition, the FDA will require that a Medication Guide be included with all bisphosphonate medications approved for osteoporosis indications to better inform patients of the risk for atypical femur fracture."

References

• Porrino JA Jr, Kohl CA, Taljanovic M, Rogers LF. Diagnosis of proximal femoral insufficiency fractures in patients receiving bisphosphonate therapy. AJR Am J Roentgenol. 2010 Apr;194(4):1061-4.
• Rogers LF, Taljanovic M. FDA statement on relationship between bisphosphonate use and atypical subtrochanteric and femoral shaft fractures: a considered opinion. AJR Am J Roentgenol. 2010 Sep;195(3):563-6.
• Shane E. Evolving data about subtrochanteric fractures and bisphosphonates. N Engl J Med. 2010 May 13;362(19):1825-7.