Etiological Analysis and Treatment Principles of Atypical Femur Fracture

Purpose: To discuss the etiology and clinical characteristics of atypical femur fracture (AFF) and to improve AFF recognition.Methods: The clinical data of AFF patients treated in our hospital from January 2007 to June 2020 were retrospectively analyzed, and the clinical characteristics of AFF were summarized.Results: Sixteen patients (24 femurs, eight bilateral femurs), including 14 females, with a median age of 73 years (53-85 years old), were included in this study. The etiological factors were divided into four categories: (1) administration of bisphosphonates (BPs), (2) severe osteoporosis, (3) hip joint dysfunction, and (4) structural abnormality of the femur. Six femurs with incomplete fractures received conservative treatment. Three femurs with incomplete fractures and 13 femurs with complete fractures received intramedullary nail treatment, and one patient (bilateral femurs) underwent plate fixation. All patients were followed up until fracture union; the follow-up time was 3-14 months.Conclusions: For high-risk patients, if there are prodromal symptoms or a simple transverse fracture of the femur, the possibility of AFF should be considered. At the sametime, imaging examinations should be performed to exclude the presence of AFF on the contralateral side.

Risk of complete atypical femur fracture with Oral bisphosphonate exposure beyond three years

Background Bisphosphonate (BP) therapy has been associated with atypical femur fracture (AFF). However, the threshold of treatment duration leading to increased AFF risk is unclear. In a retrospective cohort of older women initiating BP, we compared the AFF risk associated with treatment for at least three years to the risk associated with treatment less than three years. Methods We used observational data from a large population of female members of an integrated healthcare system who initiated oral BP during 2002–2014. Women were retrospectively followed for incident AFF confirmed by radiologic adjudication. Demographic data, pharmacologic exposures, comorbidity, bone density, and fracture history were ascertained from electronic health records. Inverse probability weighting was used to estimate risk differences comparing the cumulative incidence (risk) of AFF if women discontinued BP within three years to the cumulative incidence of AFF if women continued BP for three or more years, adjusting for potential time-dependent confounding by the aforementioned factors. Results Among 87,820 women age 45–84 years who initiated BP (mean age 68.6, median T-score − 2.6, 14% with prior major osteoporotic fracture), 16,180 continued BP for three or more years. Forty-six confirmed AFFs occurred during follow-up in the two groups. AFF-free survival was greater for BP treatment < 3 years compared to treatment ≥3 years (p = 0.004 comparing areas under survival curves). At five years, the risk of AFF was 27 per 100,000 (95% confidence interval, CI: 8–46) if women received BP treatment < 3 years and 120 per 100,000 (95% CI: 56–183) if women received BP treatment ≥3 years (risk difference 93 per 100,000, 95% CI: 30–160). By ten years, the risks were 27 (95% CI: 8–46) and 363 (95% CI: 132–593) per 100,000 for BP treatment < 3 and ≥ 3 years, respectively (risk difference 336 per 100,000, 95% CI: 110–570). Conclusions Bisphosphonate treatment for 3 or more years was associated with greater risk of AFF than treatment for less than 3 years. Although AFFs are uncommon among BP-treated women, this increased risk should be considered when counseling women about long-term BP use. Future studies should further characterize the dose-response relationship between BP duration and incident AFF and identify patients at highest risk.