Atypical femoral fractures

Osteoporotic fracture is associated with significant morbidity and mortality. Rahmani and Morin have reviewed the evidence supporting the use of oral bisphosphonates as first line therapy for postmenopausal women and older men with osteoporosis and/or fragility fractures. 1 Bisphosphonates reduce the risk of future fractures and their 10-year safety profile had appeared to be satisfactory. 2 However, long-term bisphosphonate use has been reported to contribute to the presentation of atypical femoral fractures, raising concern about long-term safety.

We recently sought to examine this potential risk in Australia through a national survey (April–August 2009). Questionnaires were sent to 750 orthopedic surgeons and 237 returned completed information. Of 15 463 patients treated with any acute fractures in the previous 12 months, 10 patients were considered to have had atypical femoral fractures. The estimated incidence of atypical femoral fractures was 0.6 per 1000 fractures. Patient details revealed a predominance of female sex, atraumatic fractures, corticosteroid use, tobacco smoking and underlying malignancy. Four patients were reported to have had osteoporosis. Only two had been treated with a bisphosphonate, alendronate.

The limited relationship to bisphosphonate is consistent with a Danish study suggesting similar incidence of atypical fractures in individuals treated or not with bisphosphonates. 3 As bisphosphonate therapy has been shown to approximately halve the risk of fractures, it is important to balance this benefit against the rare event of atypical femoral fracture, which also appears to have limited relationship to bisphosphonate use.