Bone cross-sectional geometry is not associated with atypical femoral fractures in Asian female chronic bisphosphonate users

• Published in: Bone (New York, N.Y.) Vol. 79; pp. 170 - 175
• Main Authors: Chou, Andrew Chia Chen, Ng, Alvin Choong Meng, Png, Meng Ai, Chua, David Thai Chong, Ng, David Chee Eng, Howe, Tet Sen, Koh, Joyce Suang Bee
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.10.2015
• Subjects: Absorptiometry, Photon; Aged; Asian Continental Ancestry Group; Atypical femoral fracture; Bisphosphonates; Bone Density - physiology; Bone Density Conservation Agents - adverse effects; Compressive Strength; Diphosphonates - adverse effects; Female; Femoral Fractures - pathology; Femoral Fractures - physiopathology; Hip morphology; Hip structural geometry; Humans; Middle Aged; Neck shaft angle; Orthopedics; Osteoporosis; Tensile Strength; Hip morphology; Osteoporosis; Hip structural geometry; Atypical femoral fracture; Neck shaft angle; Bisphosphonates
• DOI: 10.1016/j.bone.2015.06.003
• ISSN: 8756-3282

Abstract Introduction Atypical femoral fractures (AFF) tend to occur in Asian women with prolonged bisphosphonate exposure. Hip geometry is thought to contribute to the risk of AFF formation. We examined the hip structural geometry parameters in Asian female chronic bisphosphonate users who sustained an AFF and compared them to chronic bisphosphonate users who did not sustain any femoral fracture (NFF) and bisphosphonate-naïve patients who sustained an osteoporotic femoral fracture (OFF). Materials & methods Thirty-one patients with AFFs were gender and age-matched to 31 patients with NFFs and 49 patients with OFFs. The Hip Structural Analysis parameters analyzed were bone mineral density (BMD), cross-sectional area (CSA; a metric of resistance to axial compression), section modulus (SM; a metric of resistance to tensile loads), average cortical thickness (ACT; mean thickness of the femoral cortices), buckling ratio (BR; an index of likelihood of local buckling), and neck shaft angle (NSA; the angle between the neck and shaft axes). The regions analyzed were three cross-sections measured at the narrowest femoral neck diameter, the intertrochanteric area, and the proximal femoral shaft. One-way ANOVA with Bonferroni adjustment for multiple comparisons was used to compare parameters between the three patient groups, with statistical significance defined as p < 0.05. Results There were no statistical differences in parameters between patients with AFFs and patients with NFFs at all measured regions. Patients with AFFs and NFFs had statistically higher BMD, CSA, ACT, SM values and lower BR values at the NN and IT regions than patients with OFFs. Additionally, patients with NFFs had statistically higher SM values at the IT region than patients with OFFs, while patients with AFFs had statistically higher BMD, CSA, and ACT values at the FS region. All other measured parameters were not statistically different between the groups. Conclusions Chronic bisphosphonate users with and without AFFs had similar femoral structural geometries. Unlike in other populations, varus neck shaft angles were not found to be associated with AFFs in Asian female chronic bisphosphonate users. Thus, bone cross-sectional geometry is not likely to be associated with AFFs in Asian female chronic bisphosphonate users. Hip Structural Analysis does not show an increased predilection for tensile failure in AFFs.