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Femur strength predictions by nonlinear homogenized voxel finite element models reflect the microarchitecture of the femoral neck

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Gianluca Iori, Laura Peralta Pereira, Andreas Reisinger, Frans Heyer, Caroline Wyers, Joop van den Bergh, Dieter Pahr, Kay Raum

Original languageEnglish
JournalMedical Engineering & Physics
Publication statusAccepted/In press - 18 Mar 2020

King's Authors

Abstract

Introduction: In the human femoral neck, the contribution of the cortical and trabecular architecture to mechanical strength is known to depend on the load direction. Here, we investigate if QCT-derived homogenized voxel finite element (hvFE) simulations of varying hip loading conditions can be used to study the architecture of the femoral neck. Methods: The strength of 19 pairs of human femora was measured ex vivo using nonlinear hvFE models derived from high-resolution peripheral QCT scans (voxel size: 30.3 μm). Standing and side-backwards falling loads were modeled. Quasi-static mechanical tests were performed on 20 bones for comparison. Associations of femur strength with volumetric bone mineral density (vBMD) or microstructural parameters of the femoral neck obtained from high-resolution QCT were compared between mechanical tests and simulations and between standing and falling loads. Results: Proximal femur strength predictions by hvFE models were positively associated with the vBMD of the femoral neck (R² > 0.61, p < 0.001), as well as with its cortical thickness (R² > 0.27, p < 0.001), trabecular bone volume fraction (R² = 0.42, p < 0.001) and with the first two principal components of the femoral neck architecture (R² > 0.38, p < 0.001). Associations between femur strength and femoral neck microarchitecture were stronger for one-legged standing than for side-backwards falling. For both loading directions, associations between structural parameters and femur strength from hvFE models were in good agreement with those from mechanical tests. Conclusion: hvFE models reflect the load-direction-specific contribution of the femoral neck microarchitecture to femur strength.

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