Transverse and Oblique Long Bone Fracture Evaluation by Low Order Ultrasonic Guided Waves: A Simulation Study

Abstract

Ultrasonic guided waves have recently been used in fracture evaluation and fracture healing monitoring. An axial transmission technique has been used to quantify the impact of the gap breakage width and fracture angle on the amplitudes of low order guided wave modesS0andA0under a 100 kHz narrowband excitation. In our two dimensional finite-difference time-domain (2D-FDTD) simulation, the long bones are modeled as three layers with a soft tissue overlay and marrow underlay. The simulations of the transversely and obliquely fractured long bones show that the amplitudes of bothS0andA0decrease as the gap breakage widens. Fixing the crack width, the increase of the fracture angle relative to the cross section perpendicular to the long axis enhances the amplitude ofA0, while the amplitude ofS0shows a nonmonotonic trend with the decrease of the fracture angle. The amplitude ratio between theS0andA0modes is used to quantitatively evaluate the fracture width and angles. The study suggests that the low order guided wave modesS0andA0have potentials for transverse and oblique bone fracture evaluation and fracture healing monitoring.