Incidence and medical management of bisphosphonate-associated atypical femoral fractures in a major trauma centre: a retrospective observational study

Neil Eisenstein, Ganesh Kasavkar, Dhruva Bhavsar, Faisal Shehzaad Khan, Zoe Paskins

Atypical femoral fractures (AFFs) are rare events associated with increased duration of bisphosphonate exposure. Recommended management of AFFs include cessation of bisphosphonates and imaging of the contralateral femur. The aims of this study were to identify the local incidence of AFFs in bisphosphonate users and to audit the medical management of AFFs against published recommendations. A retrospective analysis of the admissions database for a major trauma centre identified all femoral fractures (3150) in a five-year period (July 2009 to June 2014). Electronic health records and radiographs were reviewed using the 2013 American Society for Bone and Mineral Research (ASBMR) diagnostic criteria for AFF to establish the number of cases. To estimate incidence, the total number of bisphosphonate users was derived from primary care prescription and secondary care day-case records. Medical management of cases with AFF on bisphosphonates was audited against guidance from ASBMR and Medicines & Healthcare Products Regulatory Agency. 10 out of 3150 femoral fractures met criteria for AFF; 7 of these patients had a history of exposure to bisphosphonates (6 oral, 1 intravenous). There were 19.1 AFFs per 100,000 years of bisphosphonate use in our region. Bisphosphonates were stopped and the contralateral femur imaged in only 2 of the 7 patients treated with bisphosphonates. Our local incidence is in line with published figures; however, this is the first published evidence suggesting that medical management and identification of AFF may be suboptimal. Managing these patients remains challenging due to their rarity and possible lack of awareness.