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Are atypical femur fractures linked with oral bisphosphonate use?



DOI:10.1038/bonekey.2012.70

This retrospective study sought to find out more about the atypical femoral shaft (FS) fractures that have been observed in patients taking oral bisphosphonates, and that may be related to bone micro-damage linked to a drug-induced reduction in bone turnover.

When a total of 5034 fractures were evaluated, the cumulative incidence of an atypical FS fractures with major features (AFM) was 18.2 per 100 000 person years [95% CI=16.0–20.7] and the cumulative incidence of atypical FS fractures with additional minor atypical features apparent by radiography (AFMm) was 5.9 per 100 000 person years [95% CI=4.6–7.4].

In general, FS fractures of all subtypes were not significantly associated with taking oral bisphosphonates, but bisphosphonate therapy was associated with those classified as atypical FS fractures that showed additional minor features in radiographs. However, the fracture rates remained similar over a long study period (13.5 years) while bisphosphonate dispensing increased.

Editor's comment: Only a minority of FS fractures show atypical features so it is important to use radiography to evaluate whether they are associated with bisphosphonate therapy. This study revealed that patients taking bisphosphonates were no more likely than controls to sustain an atypical FS fracture with major features but they were at increased risk of FS fractures with minor features. The association between bisphosphonate use and atypical femoral fractures warrants further investigation.


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