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* Cite as: CMAJ 2017 April 10;189:E542. doi: 10.1503/cmaj.l60450
1 Atypical femoral fracture is an uncommon complication of longterm use of bisphosphonates
Long-term use of bisphosphonate is defined as greater than three years for the treatment of osteoporosis.1 This type of fracture accounts for 1.1% of all femoral fractures, with an age-adjusted incidence rate of 1.8 to 113 cases per 100000 personyears for bisphosphonate exposure of less than 2 years to 8-10 years, respectively.1 Number needed to harm is about 1 per 2000 per year of bisphosphonate use.2 Atypical femoral fractures can occur in the absence of osteoporosis treatment.
2 Atypical femoral fractures are stress or insufficency fractures occurring in the femoral shaft
Bisphosphonates inhibit osteoclasts and decrease bone remodelling that may lead to accumulation of microdamage and stress fracture in the femoral shaft (below the lesser trochanter and proximal to...