Published: November 2009

Alendronate - risk of low-energy femoral shaft fracture

Prescriber Update 30(4): 25
November 2009

A number of published case reports have described atypical low energy stress fractures of the subtrochanteric and proximal femoral shaft in patients taking alendronate long-term.1-3 In some cases the patient experienced prodromal pain in the affected area weeks to months before a complete fracture occurred.

Prescribers are advised to consider the risk of atypical stress fractures in alendronate-treated patients reporting pain of the subtrochanteric or proximal femoral shaft. It is important to note that the reported alendronate-associated fractures were frequently bilateral; therefore the contralateral femur should be examined if a fracture is suspected.

Factors which may increase the risk of fractures include: vitamin D deficiency, malabsorption, glucocorticoid use, previous stress fracture, lower extremity arthritis or fracture, extreme or increased exercise, diabetes mellitus, and chronic alcohol abuse.

It is important to note that atypical stress fractures have also been reported in patients not taking bisphosphonates. In addition, it is possible that other bisphosphonates may be associated with an increased risk of atypical stress fractures.

Medsafe advises that the interruption of bisphosphonate therapy in patients with atypical stress fractures should only be considered following an individual risk-benefit assessment.

  1. Kwek EB, Goh K, Koh JSB, Png MA, et al. An emerging pattern of subtrochanteric stress fratures: A long-term complication of alendronate therapy. Injury 2008;39:224-231.
  2. Lenart BA, Lorich DG, Lane JM. Atypical fractures of the femoral diaphysis in postmenopausal women taking alendronate. New England Journal of Medicine 2008;358(12):1304-6.
  3. Neviaser AS, Lane JM, Lenart BA, et al. Low energy femoral shaft fractures associated with alendronate use. Journal of Orthopaedic Trauma 2008;22:346-50.