Long cortical bone fracture evaluation using ultrasonic guided waves: A tubular phantom study

Abstract

Mode conversion theory seems to be promising for interpretation of the guided mode propagation in the fractured and healing long bone. In the study, long cortical bone was modelled as a tubular structure and the transmission characteristics of two fundamental longitudinal modes L(0,1) and L(0,2) were investigated by axial transmission method. Acrylic pipes were involved as the bone phantoms in the experiments. To imitate different fracture statuses, artificial notches were circumferentially sawed on the phantom pipes with varying fracture depth from 0 to 80% of the thickness. In parallel to the experiments, numerical simulations were performed using three-dimension finite-difference time-domain (3D-FDTD) method. Mode interaction between the longitudinal modes L(0,1) and L(0,2) was quantified by the energy percentage parameters. Both numerical simulation and phantom experiment indicated that the longitudinal mode conversion correlated strongly with fracture depth, which may offer great potentials for the long bone fracture evaluation.