EVALUATION OF MECHANICAL PROPERTY OF FRACTURE HEALING USING NON-DESTRUCTIVE TESTING

用扫描声学显微镜观察骨的声学各向异性。术后12周，从4只比格犬中采集骨折和完好的胫骨。观察了三种测量模式：C型成像、XZ型成像和超声速度测量。通过旋转安装在超声波振荡器上的狭缝透镜，在0度和90度方向上测量纵向弹性波的超声波速度。本文研究了正常胫骨皮质骨和骨折愈合处骨单位的各向异性，即在与皮质骨长轴平行和垂直的方向上超声速度的差异。在横截面和纵向上，骨单位中心管附近的内部区域的速度始终低于外部区域的速度。两个区域之间的流速差在200 - 300米/秒之间。横截面骨单位无声学各向异性。同时，在纵切面骨单位中，平行于中央管长轴方向的流速始终高于垂直于长轴方向的流速。两个方向的速度差在800 ~ 900 m/s之间。在骨折胫骨愈合部位，骨痂区几乎没有表现出各向异性，尽管原始皮质区保持其各向异性。

Acoustic anisotropy of bone was using the scanning acoustic microscope. Both fractured and sound tibias were harvested from four beagle dogs 12 weeks postoperatively. Three kinds of measurement mode were observed : C-mode imaging, XZ-mode imaging and measurement of ultrasound velocity. Ultrasound velocity of longitudinal elastic wave was measured in the directions of 0 and 90 degrees by rotating a slit lens attached to an ultrasound oscillator. Anisotropy, the difference of ultrasound velocity both in the parallel and rectangular directions to the long axis of the cortical bone, was studied on the osteons in the cortical bones of normal tibias and on the healing site of the fractured tibias. The velocity in the inner area near the central canal of the osteon was constantly lower than that in the outer area both in the cross section and the longitudinal one. The difference of the velocity between the two areas ranged from 200 to 300m/sec. There was no acoustic anisotropy in cross-sectional osteons. Meanwhile, in the osteons longitudinally sectioned, the velocity was constantly higher in the direction parallel to the long axis of the central canal than in the direction rectangular to the axis. The difference of the velocity between the two directions ranged from 800 to 900m/sec. In the healing site of the fractured tibias the callus area showed little anisotropy, although the original cortical area maintained its anisotropy.