Correspondence Atypical Femur Fractures Associated With Diphosphonate Use To the Editor: I read with great interest the recent article on atypical femur fractures associated with diphosphonate use.1 In the article abstract, the authors repeatedly stress the “subtrochanteric region of the femur” as the location of atypical femur fractures. Although atypical femur fractures are most commonly observed in the proximal one third of the femoral shaft, it is generally agreed that such can occur anywhere along the femur, from just distal to the lesser trochanter to just proximal to the supracondylar flare of the femoral metaphysis.2-4 In our collection of atypical femur fractures, only a third of 83 fractures were located in the subtrochanteric region, within 5 cm of the lower border of the lesser trochanter. It is an important message to your readers that atypical femur fractures do occur along the whole length of the femur shaft and are not restricted to the subtrochanteric region. Dr. W. Y. Shen Kowloon, Hong Kong

The Author Replies: Thank you for your interest in our recent review article.1 We acknowledge that atypical fractures can occur in areas

of the femur other than the subtrochanteric femur. We focused our description on those within the subtrochanteric region of the femur because this is the most commonly encountered anatomic site, and we focused our review on the treatment of atypical fractures, regardless of their anatomic site. We appreciate that you shared your own data to help support the fact that these fractures can occur outside the subtrochanteric femur. Tessa Balach, MD Farmington, CT

References 1. Balach T, Baldwin PC, Intravia J: Atypical femur fractures associated with diphosphonate use. J Am Acad Orthop Surg 2015;23(9):550-557. 2. Shane E, Burr D, Abrahamsen B, et al: Atypical subtrochanteric and diaphyseal femoral fractures: Second report of a task force of the American Society for Bone and Mineral Research. J Bone Miner Res 2014; 29(1):1-23. 3. Einhorn TA, Bogdan Y, Tornetta P III: Bisphosphonate-associated fractures of the femur: Pathophysiology and treatment. J Orthop Trauma 2014;28(7):433-438. 4. Meling T, Nawab A, Harboe K, Fosse L: Atypical femoral fractures in elderly women: A fracture registry-based cohort study. Bone Joint J 2014;96-B(8): 1035-1040.

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Journal of the American Academy of Orthopaedic Surgeons

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