Do bisphosphonates cause femoral insufficiency fractures?

In recent years, several reports have suggested an association between the use of bisphosphonates and subtrochanteric insufficiency fractures. Research from animal studies and in some cases from histomorphometric data collected from patients provide evidence of a possible pathophysiological mechanism behind this phenomenon. Despite this, it has not yet been possible to confirm a causal relationship. The small number of cases, the lack of consistency in defining these atypical fractures, the absence of homogeneity between studies, and the fact that most data available are derived from retrospective observational studies, are some of the difficulties encountered in the evaluation of evidence. Despite the proven benefit of bisphosphonates at providing protection against osteoporotic fractures, caution should be used before continuing therapy for longer than 5 years.