Prevalence of atypical femoral fractures, a clinical update: A comparative retrospective study 7 years later.

Introduction: Atypical femoral fractures (AFFs) are a rare type of subtrochanteric or diaphyseal fracture frequently associated with the use of bisphosphonates (BPs). They are a clinical entity often overlooked, for which a correct clinical-instrumental classification is essential for a successful treatment. Nowadays, there is no accurate data on their real incidence. The aim of this work is to evaluate the period prevalence of AFFs and their risk factors, and to compare actual results with a previous study conducted at the same Institution seven years previously.

Materials and methods: The same methodology used in the previous study, conducted by the same Authors, was applied. Radiographs of all subtrochanteric and diaphyseal femoral fractures in patients over 60 years treated at a single Institution between January 2018 and February 2020 were reviewed, and cases that displayed the AFFs definition criteria were identified. Current and previous medical and pharmacological history were collected, and osteometabolic evaluation through the execution of first level blood tests, with the addition of a valuation of 25(OH)-vitamin D and parathormone was performed.

Results: Out of 40 subtrochanteric or diaphyseal femoral fractures in patient aged 60 years or older, four cases (10 %) presented a characteristic radiographic pattern significative for AFFs, in comparison with a 5 % observed in the previous study. All four patients were women with a positive (current or previous) history of BPs consumption.

Discussion: The efficacy of BPs for the prevention of osteoporotic fractures is widely demonstrated. However, particularly prolonged use of these drugs may increase the risk of developing AFFs in some patients. The incidence of AFFs is higher than that reported in the literature, if evaluated only for the subtrochanteric and diaphyseal sites (essential diagnostic criterion in the definition of AFFs). In our study, the incidence of AFFs doubled after seven years. The present data also confirm the frequent association between the use of BPs and the onset of AFFs.