骨盆体位改变对模拟髋臼假体前倾角测量的影响

Effects of pelvic orientation on the anteveration measurement of simulated acetabular cup

背景:利用骨盆正位片测量髋臼假体放置角度是目前常用的评估人工髋关节置换效果的方法,骨盆体位的非标准化影响测量结果的准确性并使得相互比较较为困难。目的:试图了解骨盆体位变化时,髋臼假体前倾角测量的相应变化情况,以提高临床评价的准确性和比较研究的可比性。方法:自制系列前倾角模拟髋臼假体模型,分别代表0°,10°,20°,30°,40°前倾角。按35°,40°,45°,50°,55°外展角分别放置于6具防腐骨盆标本髋臼窝内,使骨盆标本沿冠状轴、矢状轴在±30°的范围内按5°/次分别旋转,保持X射线投照中心点始终与标准骨盆正位片投照中心点一致。摄X射线平片并进行前倾角测量。结果与结论:骨盆沿冠状轴或矢状轴每旋转1°,髋臼假体前倾角测量值变化为0.61°～0.73°,其中沿冠状轴向前旋转和沿矢状轴远离放射源时前倾角呈减小趋势,沿冠状轴向后旋转和沿矢状轴接近放射源时前倾角呈增加趋势,临床评价时应充分考虑骨盆体位因素对测量结果的影响。

BACKGROUND：Acetabular cup orientation using a standard radiograph of the pelvis is quite common method to assess artificial hip replacement nowadays.Non-standardization of pelvic orientation affected accuracy of measurement results,and it is difficult to compare.OBJECTIVE：To make sure how pelvis tilting affect the anteveration of the cup and to elevate clinical accuracy and compare study comparability.METHODS：Designed a simulated acetabular cup with serial concentric circles which pass through the same polars and represent anteveration of 0°,10°,20°,30°,40°.Loaded the simulated acetabular cup at an inclination of 35°,40°,45°,50°,55° to 6 cadaver pelves.Made the pelves tilt around the frontal axis and sagittal axis with 5° each time in a scope of ± 30°.Take standard radiograph of the pelvis accordingly.Radiograph was photographed and frontal angle of dip was measured.RESULTS AND CONCLUSION：Pelvic tilt of about 1° causes measuring errors of anteveration 0.61°-0.73°.The anteveration decreased at both acetabular cups when pelvic posterior tilt and at the acetabular cup that near the X-ray source as pelvic lateral tilt.The anteveration rose at both acetabular cups when pelvic anterior tilt and at the acetabular cup that away from the X-ray source as pelvic lateral tilt.During clinical evaluation,pelvic orientation effects on measurement results should be considered.