Identification of subtrochanteric and femoral shaft fractures as atypical femur fractures on radiology reports.

Background: Bisphosphonate-associated stress fractures, atypical femur fractures (AFF), are a rare subgroup of femoral stress fractures. Their correct and early diagnosis is imperative for appropriate treatment.

Purpose: To investigate the sensitivity of written radiology reports to mention radiographic features of AFF, depending on the time period and academic level of the hospital.

Material and methods: We used 171 patients, aged 55 years or older, who sustained an AFF between 2008 and 2010 (early period) identified through the Swedish National Patient Register and radiographic review and 104 patients identified through the Swedish Fracture Register between 2015 and 2018 (late period). Plain radiographs were extracted from 72 radiology departments in Sweden and individually re-reviewed and classified based on the American Society for Bone and Mineral Research case definition for AFF. Radiology reports were viewed for mentioning AFF or stress/insufficiency features (true positives). The number of true positives was compared with the number of false positives for both periods using non-parametric statistics and using the gold standard as reference.

Results: We obtained 98 of the possible 171 reports with 7% of true positives for the early period and 77 of the possible 104 reports with 27% true positives for the late period (P < 0.001). The level of improvement over time was independent of the academic level of the hospital.

Conclusion: Despite improvements over time, written radiology reports seldom mention AFF features. Clinicians, specifically orthopedic surgeons, are encouraged to contribute to a correct and early diagnosis to tailor treatment, while awaiting improvements in radiology reports.