The clinical characteristics of patients with hip fractures in typical locations and atypical femoral fractures

A Summary The pathophysiology of atypical fractures is unknown. We compared characteristics of patients with atypical femoral fractures and hip fractures in typical locations of the femur. Patients with atypical fracture reported a longer duration of use of bisphosphonates, had higher body mass index, and higher total hip bone mineral density. Further studies are needed. Introduction This study aims to describe the characteristics of patients with typical and atypical fractures of the femur assessed in a tertiary care osteoporosis center. Methods We abstracted clinical, laboratory, and radiographic data on subjects with a history of a low-impact fracture at the femur and/or hip (confirmed by review of radiograph and/or radiology report) from January 2008 to October 2011. Available radiographs were reviewed and fracture categorized as typical or atypical by a radiologist blinded to the original diagnosis. Results Radiology reports were available for 72 subjects: 40 hip fractures in typical locations (typical fracture), 16 atypical femoral fracture (atypical fracture), and 16 were excluded. While both those with typical and atypical fractures reported taking bisphosphonates at the time of fracture, duration of use was longer with atypical fractures (104.2 +/- 42.0 months) compared with typical (71.1 +/- 62.8 months) (p=0.04). Body mass index (BMI) was higher in patients with atypical fractures (26.2 +/- 3.2 kg/m(2)) than in those with typical (23.1 +/- 4.3 kg/m(2)) (p=0.006). Total bone mineral density (BMD) was higher in patients with atypical fracture (0.795 +/- 0.102) versus typical (0.686 +/- 0.130) (p=0.003) Previous history of cancer was reported by 7 of 16 patients with atypical and 7 of 40 patients with typical fracture (p=0.04). Conclusions Compared to those with typical fractures, patients with atypical fracture report a longer duration of use of bisphosphonates, higher BMI, and higher total hip BMD. Future studies should examine if these differences contribute to the pathophysiology of atypical fractures.