Dodd Simon P, Cunningham James L, Miles Anthony W, Gheduzzi Sabina, Humphrey Victor F
Centre for Orthopaedic Biomechanics, Department of Mechanical Engineering, University of Bath, Bath, Avon, UK.
Ultrasound Med Biol. 2008 Mar;34(3):454-62. doi: 10.1016/j.ultrasmedbio.2007.09.002. Epub 2007 Nov 12.
An axial transmission technique has been used to investigate the changes in the first arrival time and signal amplitude of 200 kHz ultrasonic waves travelling across different fracture geometries. Results taken from intact bovine femora were compared with those produced when a transverse and an oblique fracture were simulated. The arrival time and signal amplitude displayed a different variation with receiver position for the two geometries and a given fracture gap width. A comparison between this work and a previous study suggested that the marrow does not play a significant role in the mechanisms causing the change in arrival time and signal amplitude. Numerical modelling revealed that an oblique fracture caused a reduction in the extra time delay of the propagating wave compared with the transverse case, but a decrease in the corresponding signal amplitude, i.e., greater signal loss. The angle of the oblique fracture was investigated and results suggested that decreasing the fracture angle relative to the wave propagation direction caused a decrease in the extra time delay and an increase in signal loss. These findings are important for determining the sensitivity of systems for monitoring fracture healing using ultrasound arrival time and signal amplitude. (E-mail: spd@inorbit.com).
一种轴向传输技术已被用于研究200千赫超声波穿过不同骨折几何形状时的首次到达时间和信号幅度的变化。将完整牛股骨的结果与模拟横向骨折和斜向骨折时产生的结果进行了比较。对于两种几何形状以及给定的骨折间隙宽度，到达时间和信号幅度随接收器位置呈现出不同的变化。这项工作与之前一项研究的比较表明，骨髓在导致到达时间和信号幅度变化的机制中不起重要作用。数值模拟显示，与横向骨折情况相比，斜向骨折导致传播波的额外时间延迟减少，但相应的信号幅度降低，即信号损失更大。对斜向骨折的角度进行了研究，结果表明，相对于波传播方向减小骨折角度会导致额外时间延迟减少和信号损失增加。这些发现对于确定利用超声到达时间和信号幅度监测骨折愈合的系统的灵敏度很重要。（电子邮件：spd@inorbit.com）
