Lieberman Elizabeth G, Jansen Kirsten, Mast Laurel, Brady Jacqueline M, Yoo Brad J
Oregon Health and Science University, Sam Jackson Hall, S.W. Sam Jackson Park Road, Portland, OR.
OTA Int. 2018 May 16;1(1):e004. doi: 10.1097/OI9.0000000000000004. eCollection 2018 May.
Anatomic rotational reduction of diaphyseal femur fractures is essential in restoring limb mechanics. Errors in reproducing anteroposterior (AP) or lateral knee reference radiographs of the contralateral limb could result in inaccuracies during rotational reduction. The objective of this study was to examine whether fluoroscopic rotational variation can be observed with the same degree of precision with AP and lateral distal femur projections.
AP and lateral radiographs were obtained from intact knees of 7 cadaveric specimens using fluoroscopy. The lateral condylar width and coronal femoral width from the AP images and the posterior condylar offset and sagittal femoral width from the lateral images were measured by 3 reviewers. Interclass correlation coefficients (ICCs) among the 3 reviewers were calculated. The mean data from all reviewers were plotted against angle of rotation, and the slope () and regression of the line were then determined.
ICCs were 0.997 (lateral) and 0.994 (AP), demonstrating excellent interobserver agreement. The mean (±SD) value for lateral images was 0.016 ± 0.001 and for AP images was 0.009 ± 0.001 (.0001). The higher lateral value represents a more appreciable difference in size of the measured segment for the same rotational change.
The observed rotational change was 1.76 times greater on lateral images compared to AP images; thus, the lateral images may be more precise as a reference for rotation. The routine use of lateral knee radiographs to guide intraoperative rotational alignment of the femur may therefore be justified.
股骨干骨折的解剖旋转复位对于恢复肢体力学至关重要。对侧肢体前后位（AP）或侧位膝关节参考X线片复制过程中的误差可能导致旋转复位不准确。本研究的目的是检验在股骨远端AP位和侧位投照下，能否以相同的精度观察到透视下的旋转变化。
使用透视从7具尸体标本的完整膝关节获取AP位和侧位X线片。由3名观察者测量AP位图像上的外侧髁宽度和股骨冠状面宽度，以及侧位图像上的后髁偏移和股骨矢状面宽度。计算3名观察者之间的组内相关系数（ICC）。将所有观察者的平均数据与旋转角度作图，然后确定直线的斜率（）和回归情况。
ICC分别为0.997（侧位）和0.994（AP位），表明观察者间一致性极佳。侧位图像的平均（±标准差）值为0.016±0.001，AP位图像为0.009±0.001（P<0.0001）。较高的侧位值表示相同旋转变化下测量节段大小的差异更明显。
与AP位图像相比，侧位图像上观察到的旋转变化大1.76倍；因此，侧位图像作为旋转参考可能更精确。因此，常规使用膝关节侧位X线片来指导股骨术中旋转对线可能是合理的。
