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Atypical Femoral Fracture -What Radiologists need to know?

Last Updated on November 8, 2020

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 trauma Increased cortical thickness of the femoral diaphysis
Fracture originating at the lateral cortex and being substantially transverse Bilaterality
Complete fractures extending through both cortices Delayed fracture healing. 
Localized periosteal or endosteal cortical thickening A 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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  1. Managing Osteoporosis Patients after Long-Term Bisphosphonate Treatment.
  2. Grainger & Allison’s Diagnostic Radiology

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Dr. Amar Udare, MD

Dr. Amar Udare has completed medical school from KEM Hospital Mumbai and radiology residency from Tata Memorial Hospital, Mumbai. He is a board-certified radiologist.

He has also completed fellowships in body imaging from Mumbai and Ottawa and is currently pursuing a fellowship in cross-section imaging at McMaster University, Canada.

He has a passion for teaching and his area of interest is body imaging. He started the website, RadioGyan to share radiology resources and cases to help residents and radiologists (#FOAMrad #radiology). He was a semi-finalist for the 2018 and 2020 Aunt-Minnie Most effective Radiology Educator Award.

You can read my most recent publications on: PubMed and Google Scholar

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