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Table 1 American Society for Bone and Mineral Research Task Force 2013 Revised Case Definition of AFF

From: Atypical femoral fracture in patients with bone metastasis receiving denosumab therapy: a retrospective study and systematic review

To satisfy the case definition of AFF, the fracture must be located along the femoral diaphysis between just distal to the lesser trochanter and just proximal to the supracondylar flare. In addition, at least four of the five Major Features must be present. None of the Minor Features is required, but they are known to sometimes be associated with these fractures [14].
Major features
 1: The fracture is associated with minimal or no trauma, as after a fall from a standing height or less.
 2: The fracture line originates in the lateral cortex and is substantially transverse in its orientation, although it may become oblique as it progresses medially across the femur.
 3: Complete fractures extend through both cortices and may be associated with a medial spike; incomplete fractures involve only the lateral cortex.
 4: The fracture is noncomminuted or minimally comminuted.
 5: Localized periosteal or endosteal thickening of the lateral cortex is present at the fracture site (“beaking” or “flaring”).
Minor features
 1: Generalized increase in the cortical thickness at the femoral diaphysis
 2: Unilateral or bilateral prodromal symptoms, such as dull or aching pain in the groin or thigh
 3: Bilateral incomplete or complete femoral diaphysis fractures
 4: Delayed fracture healing
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