Incidence and Characteristics of Atypical Femoral Fractures: Clinical and Geometrical Data

Abstract

Despite the multitude of studies published on atypical femoral fractures (AFFs), a profile for patients at risk does not exist. This study aimed first at estimating AFF incidence over a 19-month-period in Quebec City using the ASBMR Task force criteria to define AFF. The medical records of patients hospitalized for hip or femoral fracture between June 1, 2009, and December 31, 2010, were reviewed. Thirty-six cases of atypical fractures were identified during the 19-month period, representing an AFF incidence of 7.0 (range, 4.7 to 9.3) cases per 100,000 person-years. In the second part of the study, data regarding the characteristics suspected of increasing the risks of AFF were collected from medical and pharmacological records, proximal femur radiographs, and patient interviews. The data regarding each patient with an AFF during years 2008-2011 were compared to two controls with a hip or femoral fragility fracture or a traumatic fracture, paired for age and sex. Twenty patients with AFF were added to the 36 patients with AFF selected in the first part, thereby 56 patients with AFF were investigated. The association between the occurrence of AFF and bisphosphonates (BPs) use was proven statistically significant in multivariate analysis, odds ratio (OR) ¼ 10.39 (95% CI, 2.22 to 48.58; p ¼ 0.0029). Compared to controls, patients with AFF had excessive femoral offset (43.1 mm versus 38.3 mm, p ¼ 0.0007), proximal femoral neck angle in varus (128.9 degrees versus 134.0 degrees, p < 0.0001), and had greater proximal cortical thickness. This retrospective study confirms the low incidence of AFF, confirms its significant association with exposure to BPs, and reveals the possible contribution of proximal femoral geometry in AFF occurrence.

Osteoporosis treatment: recent developments and ongoing challenges

“…24 When used in patients who are at high risk of fracture, these drugs are estimated to prevent 80–5000 fragility fractures for each atypical femur fracture possibly induced by treatment. 65 Several steps can be taken to address this problem, 66 such as improved patient and doctor education regarding both the risk-benefit ratio of these drugs and the prodromal symptoms (eg, groin or hip pain) of atypical femur fractures; potential use of dual x-ray energy absorptiometry to monitor patients on therapy specifically for features of atypical femur fractures; 67 identification of high-risk patients using femur geometrical characteristics and other risk factors for atypical femur fractures; 68 and the development of pharmacogenomic markers identifying patients at increased risk of atypical femur fractures.…”

Genetic Risk Factors for Atypical Femoral Fractures (AFFs): A Systematic Review

“…Schilcher and colleagues showed ethnic differences in location of the AFFs, with fractures mainly occurring in the subtrochanteric region in Singapore, compared with diaphyseal in Sweden . The differences may be related to femoral geometric parameters that are more common in Asian women, such as increased femoral bowing and smaller neck‐shaft angles . Increased femoral curvature may lead to an altered distribution of loading with more tensile strain on the lateral side and more compression on the medial side of the femur.…”

Incidence of Mutations in the ALPL, GGPS1, and CYP1A1 Genes in Patients With Atypical Femoral Fractures

“…In addition, it should be pointed out that patients with AFF may also have other nongenetic factors that may predispose to this type of fracture, such as femoral and/or lower limb deformities. In this sense, recent studies have also suggested a possible contribution of proximal femoral geometry in AFF, reporting either an excessive femoral offset and femoral neck angle in varus, and/or femorotibial valgus deformities in some of these subjects …”