Finite Element Resonant Ultrasound Spectroscopy to Characterize Maturation of Cortical Bone Elastic Properties
EU International Incoming Fellowships (IIF) – Marie Curie Actions (H2020-MSCA-IF-2014)
Project duration :
- 2 ans
- April 2015
Supported researcher :
- Biophysics of Bone and Cartilage (BBC), Dept. of Physics and Mathematics, University of Eastern Finland, Finland
As one of the important issues of research on osteoporosis, tissue elasticity, i.e. the whole set of the anisotropic stiffness constants on millimeter scale, that directly determines the bone resistance and fracture risk, is still poorly assessed by the prevailing biomechanical methods. The state-of-art approach to determine bone elasticity is the conventional ultrasonic pulse method by measuring acoustic velocities along various directions of a specimen with a major drawback of sample size limitation, typically larger than 5 mm. However, studies on bone metabolism greatly relies on small animal models, e.g. rabbit, rat, and mouse, with smaller bones compared with the human bones and the cortical thicknesses are close to or even smaller than 1 mm. Resonant ultrasound spectroscopy (RUS) has been well established to measure the anisotropic elasticity of small metallic samples. However, it was known to be not applicable to high-damping materials like bone, due to the complicated extraction of resonant frequencies from the overlapping resonant peaks. The project aims to develop a new RUS method for the accurate elasticity determination of animal long bones (femora and tibiae). New strategies of a non-linear optimization and Bayesian formulation of the inverse problem, recently proposed by the host lab, will be used to overcome the material limitation of bone attenuation. Moreover, the novel combination of the finite element (FE) method and RUS (FE-RUS) will be adapted to relax the regularly-shaped sample restriction for the convenience of practical application. We will perform an extensive methodology development, including theoretical analysis, numerical simulation, signal processing, and inversion scheme. The newly advanced technology will be validated by measuring mechanical properties of cortical bone during growth and maturation in the rabbit model. The originality of the project comes from the combination of innovative technological development with multidisciplinary approaches towards the accurate determination bone elasticity in response to current technical deficiency of the small animal bone quality evaluation.