Bisphosphonates (BP) are a commonly prescribed class of drugs for the prevention of osteoporosis-related fractures. However, paradoxically, they have been recently linked to fractures in the shaft of the femur.
These fractures have been termed ‘atypical’ fractures’
There are scant reports in radiology literature on these atypical fractures.
In fact, since many physicians including radiologists are not conscious of this entity, these fractures are often not recognized as a specific condition and thus may be treated like any other fracture.
Bisphosphonates are widely used for the treatment of osteoporosis. The occurrence of atypical femoral fractures in patients taking BP was first reported by Odvina, et al.
Recently, a multidisciplinary task force of the American Society for Bone and Mineral Research (ASBMR) reexamined the key questions by reviewing the published reports of atypical femoral fractures and tried to get an insight into the pathogenesis and treatment of these fractures.
According to this task force’s criteria for the diagnosis of ‘atypical’ fractures, femoral fractures with sub-trochanteric extension, pathological fractures associated with tumors, and peri-prosthetic fractures are to be specifically excluded.
Atypical fractures have to satisfy all the major criteria, i.e., location from distal to lesser trochanter to just proximal to the supracondylar flare; no history of trauma or only minimal trauma (fall from standing height or less); transverse or short oblique configuration; complete fractures may be associated with a medial spike, while incomplete fractures involve the lateral cortex only.
The fracture begins as a small beak-like localized cortical thickening of the lateral cortex. Then, an incomplete lucent lateral stress fracture appears, which progressively extends to involve both the medial and the lateral cortices.
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