Predictors of atypical femoral fractures: experience of a Portuguese Fracture Liaison Service

Excerpt

Atypical femoral fractures (AFF) have gained recent attention due to their distinct characteristics, notably their predominant occurrence in the subtrochanteric region and association with prolonged bisphosphonates (BP) use – a frequently prescribed anti-osteoporotic medication [1, 2]. Despite their rarity, it is crucial for physicians to remain vigilant and recognise this clinical entity [3]. This report shares the experience of our Fracture Liaison Service (FLS) in addressing AFF. Our objective was to investigate the prevalence of AFF among hip fracture patients and identify associated factors. This is a retrospective case–control study, including patients over 50 years, who underwent hip fracture surgery and were observed at our FLS between September 2019 and January 2023. We classified fracture radiographs and compared demographic, clinical, biochemical features and BP purchase data between patients with AFF and those with typical osteoporotic fracture (TOF), as controls. Descriptive, univariate and multivariate logistic regression analysis were conducted using SPSS© version 29 and p value of < 0.05 was considered to be statistically significant. A total of 109 patients (9 AFF and 100 TOF) were included. Table 1 presents the baseline demographic and clinical characteristics of the included patients. Patients with AFF were younger (AFF: 71.0 ± 8.8 vs. TOF: 78.3 ± 8.6 years, p = 0.008), with a similar female sex distribution (AFF: 77.8% vs TOF: 84.0%, p = 0.457). AFF patients exhibited a higher body mass index (BMI) (AFF: 28.5 ± 5.2 vs. TOF: 24.8 ± 4.5 kg/m², p = 0.023) and a higher estimated glomerular filtration rate (eGFR) (AFF: 88.7 ± 19.3 vs. TOF: 70.9 ± 21.7 mg/dL, p = 0.027). Additionally, a significantly higher proportion had received BP treatment (77.8% vs. 14.0%, p < 0.001). No significant differences were found in the BP treatment duration, haemoglobin levels, Charlson’s Comorbidity Index, or the use of proton pump inhibitors, corticosteroids, anti-depressants or statins. Multivariate logistic regression analysis [X² (4) 29.2, p < 0.001; R² = 0.604] identified previous BP treatment and higher BMI as predictors of atypical femoral fracture (p = 0.006 and p = 0.017, respectively). Odds ratio (OR) for previous BP treatment was 58.2 (95% CI 3.1–1086.1) and, for higher BMI, it was 1.4 (95% CI 1.1–1.8). While deemed uncommon, our study revealed that 8.3% of femoral fracture patients experienced AFF, surpassing prevalence rates reported in earlier studies [4, 5]. Furthermore, our findings affirm the association between long-term BP use and AFF, echoing previous research [5, 6]. Importantly, we contribute to the growing evidence linking a higher BMI with an increased risk of AFF. Acknowledging limitations, including a small sample size and single-centre data, our work emphasizes the necessity for vigilance in recognising AFF and provides valuable insights into associated risk factors. …