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Atypical Femoral Fracture -What Radiologists need to know?

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Radiograph of a patient with atypical femoral fracture
Atypical Femoral Fractures secondary to chronic bisphosphonates therapy

What is an atypical femoral fracture ?

  • Also known as Bisphosphonate-related proximal femoral fractures.
  • Type of insufficiency fracture.
  • Usually in patients on long term bisphosphonates (>3-5 years).
  • Can be bilateral in up to 60% of cases, always screen the opposite femur.
  • Changes first occur on the lateral femoral cortex.
  • Subtrochanteric , transverse orientation, lack of comminution cortical beak; occur with low velocity trauma.
  • Associated with poor healing.

What are the diagnostic criteria for an atypical femoral fracture (AFF)?

According to the American Society for Bone and Mineral Research Taskforce, 4 of the 5 major criteria are necessary for the diagnosis of AFF.[1]

Major Criteria (4 out of 5 necessary)Minor Criteria (not necessary for diagnosis)
Minima traumaIncreased cortical thickness of the femoral diaphysis
Fracture originating at the lateral cortex and being substantially transverseBilaterality
Complete fractures extending through both corticesDelayed fracture healing. 
Localized periosteal or endosteal cortical thickeningA prodrome of thigh or groin pain.
Minimal comminution at most
Major and Minor criteria for Atypical Femoral Fractures (AFF)

What is the management for atypical femoral fractures?

Conservative management: It is reasonable to discontinue bisphosphonates, adequate calcium and vitamin D intake should be ensured, and teriparatide should be considered for those who appear not to heal with conservative therapy [1]. Results are poor and patient may eventually need surgical management.

Surgical management:

Femoral subtrochanteric and shaft fractures are usually treated with intramedullary (IM) nailing or plating

Detailed discussion with video:

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A more detailed overview of proximal femoral fractures can be found here:


  1. Managing Osteoporosis Patients after Long-Term Bisphosphonate Treatment.
  2. Grainger & Allison’s Diagnostic Radiology

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