Determination of bone properties from Lamb type of waves

Abstract

Our domain of interest is cortical bone characterization, i.e. determination of structural and material properties by means of ultrasound waves. The frequency spectrum of Lamb type of waves are the input data of the method of parameters identification, based on a least mean square algorithm. Specificities of clinical measurements of long bones require first to address the issue of measurements with limited access [Minonzio & al., J. Acoust. Soc. Am., 2010] and second, to develop methods for a combined determination of structural and elastic properties. The first physical model was the free plate under plane strain assumption for transverse isotropic materials with 4 elastic parameters and one structural (thickness). Experiments on flat plates and tubes of circular cross section are used as test case and the method was validated by comparison to independent techniques dedicated to material properties [Bernard S. & al. 2012]. The same method was applied on in vitro experiments on cortical bone samples. Here, the bone thickness was measured independently by X ray technique. This study opens the perspective of updating the physical model to determine additional relevant parameters, the tube diameter and/or the soft tissue properties in case of in vivo measurements.