中文摘要：

目的：评价数字标记点质心跟踪法在骨盆位移测量中的可靠性。方法：选择健康成人尸体骨盆标本6例,保留主要的韧带和关节囊,骨盆关键部位粘贴标记点;双足站立位,0~500 N垂直分级载荷下,CCD采集骨盆形变图像;基于Image J软件,采用数字标记点质心跟踪法测量冠状面上S1椎体的垂直位移及矢状面上骶骨相对于髂骨的角位移。结果：骨盆形变前后标记点图像具有良好的相关性,相关系数达到0.983;相对误差达到1.11‰。双足站立位,骨盆垂直载荷-位移曲线基本呈线性变化;侧位观察,骶骨相对于髂骨呈现屈曲运动,其载荷-角位移曲线呈非线性变化。500 N垂直载荷下,S1椎体垂直位移为（0.835 6±0.283 0）mm,骶骨相对于髂骨的角位移为（0.584±0.221）°。结论：基于Image J软件数字标记点质心跟踪法用于测试骨盆的位移,其测试方法简单、测试精度高,在生物力学上可以得到很广泛的应用。

英文摘要：

Objective：To evaluate the reliability of the digital marker tracing method combined with center-of-mass algorithm in measuring human pelvic displacement. Methods： Six cadaveric specimens of the third lumbar vertebra to the proximal 1/3 part of femur were used in present study. The specimens had no structural abnormality and all the soft tissues were dissected, reserving the hip joint capsules and the ligaments of the pelvic ring and floor. Markers with black dots against white background were used to mark the key points of the pelvis. Axial loadings from the proximal lumbar （simulating the two-legged stance） were applied by MTS in the gradient of 0 N to 500 N. Images of the front and lateral views were obtained using two CCD cameras. Using Image J software,we calculated the vertical displacement of Si （the first sacral vertebrae） in the front view and the micro-angular rotation of sacroiliac joint in the lateral view by measuring the marker＇s movement. Results： There was good correlation between the marked points before and after deformation of the pelvis, with the average correlation coefficient be- ing 0. 983. Based on the 768X 576 pixels, pixel size （mm） 0. 681 5×0. 681 5 image,the accuracy of the displacement was about 0. 018 pixels and the comparative error could reach 1. 11%0. The load-displacement curves obtained in this study accorded well with the clinical results. The pelvic load-displacement curve exhibited approximately a linear behavior; the sacroiliac joint loadangular rotation curve in the sagittal plane exhibited a non-linear behavior. Under a vertical load of 500 N,the average vertical displacement of Si of the pelvis was （0. 835 6±0. 283 0） mm and the average micro-angular rotation of sacroiliac joint in lateral view was （0. 584 ±0.221 ）. Conclusion： Digital marker tracing method combined with the center-of-mass algorithm is a simple, accurate method for measurement of pelvic displacement,which can be widely used in biomechanical research.