Quantitative evaluation of long bone fractures by ultrasonic guided waves

Using ultrasonic guided waves to assess fractured long bone has become one of the hottest topics in recent years. To quantitatively evaluate long bone fractures, this paper uses two-dimension finite-difference time-domain (FDTD) simulations to quantitatively analyze the transmission of guided wave in long bone with partially and completely diaphyseal osteotomy. It is illustrated that under the narrowband low-frequency excitation, two fundamental guided modes S0 and A0 can be excited successfully. Different from S0 mode, A0 mode is very sensitive to the fracture geometry. An amplitude ratio parameter between S0 and A0 (S0/A0) is proposed to quantify the bone fracture degree. The simulation indicates that S0/A0 significantly increases with the fracture deepening and widening. Thus, the guided mode conversion can be used to evaluate depth and width of the diaphyseal fracture, which may also be helpful to monitor the fracture healing of long cortical bone.