Atypical femoral fractures in elderly women: a fracture registry-based cohort study

An atypical femoral fracture (AFF), with a transverse fracture radiologically through the lateral cortex is a rare but serious condition. In order to improve our ability to identify patients with this condition, we retrospectively surveyed all subtrochanteric, peri-implant and diaphyseal femoral fractures in patients aged ≥ 65 years who underwent surgical treatment at our hospital between 2004 and 2011. We describe the incidence of atypical fractures and their characteristics, with observational data including a review of the hospital and general practitioner records. Clinical outcomes were evaluated using the Harris hip score (HHS) and the timed up-and-go (TUG) test. Atypical fractures only occurred in women with an incidence of 9.8 per 100,000 person-years. The incidence in those who were treated with bisphosphonates was 79.0 per 100,000 person-years; eight of 17 fractures occurred around metal implants. There was a high incidence of delayed union and revision surgery. A total of nine patients (ten AFFs) were available for review at a mean follow-up of 36.5 months (10 to 104). The clinical outcome was poor with a mean HHS of 58.9 (95% CI 47.4 to 70.4) and a mean TUG test of 25.7 s (95% CI 12.7 to 38.8). The delay in diagnosis and treatment of AFF may result from a lack of knowledge of this condition.