Institut de l'Appareil Locomoteur, Rangueil University Hospital, Toulouse, France.
Int Orthop. 2012 Sep;36(9):1783-8. doi: 10.1007/s00264-012-1550-5. Epub 2012 May 3.
Primary paraclinical investigation to look for femoral morphological abnormality consistent with cam-type anterior femoroacetabular impingement (FAI) must include specific radiographic projections of the hip from the following: cross-table, frog-leg or Dunn (90° and 45° flexion). We use a frog-leg type view with fixed angles as described by Chiron, obtained with the patient in a supine position, with the hip in 45° flexion-abduction and 30° external rotation. The X-ray beam is anteroposterior and centred on the femoral head. We evaluated this view by comparing it with other views in common use.
In this experimental study, we created artificial radio-opaque morphological abnormalities secured onto normal femoral necks. The femurs were placed in relation to a fixed pelvis using orthogonal landmarks, in the positions of the various radiographic views. The digital radiographs were analysed by two observers. Nineteen femurs were included to reveal a difference of 5° between the alpha angle of Nötzli et al. [11] measured on the Dunn view and the frog-leg 45/45/30 view (Student's paired test).
The highest mean values of the alpha angle of Nötzli were always obtained with the frog-leg 45/45/30 view (87.4°, 86.2°, 84.5°) and the lowest with the cross-table view. We found a mean difference of 8.95° with the 90° Dunn view (P = 0.00007), 3.44° with the 45° Dunn view (P = 0.004) and 13.47° with the cross-table view (P = 0.002).
This experimental study confirmed the value of the frog-leg 45/45/30 view in assisting diagnosis of cam-type FAI.
为了寻找与凸轮型股骨髋臼撞击症（FAI）一致的股骨形态异常，初步临床检查必须包括来自以下特定髋关节的影像学投影：蛙式位、外展外旋位（Dunn 位）或外展内旋位（90°和 45°）。我们使用蛙式位，采用 Chiron 描述的固定角度，患者仰卧，髋关节处于 45°外展-屈曲位和 30°外旋位。X 射线束从前向后，并以股骨头为中心。我们通过与其他常用视图进行比较来评估该视图。
在这项实验研究中，我们将人工制造的不透射线的形态异常固定在正常股骨颈上。使用正交的标志点，将股骨相对于固定骨盆放置在各种影像学视图的位置。两位观察者分析了数字射线照片。为了揭示 Nötzli 等 [11] 测量的 Dunn 视图上的 alpha 角与蛙式 45/45/30 视图之间的差异为 5°，我们纳入了 19 个股骨（学生配对检验）。
Nötzli alpha 角的最高平均值始终是在蛙式 45/45/30 视图中获得（87.4°、86.2°、84.5°），而在蛙式位视图中获得的最低。我们发现与 90° Dunn 视图的平均差异为 8.95°（P=0.00007），与 45° Dunn 视图的平均差异为 3.44°（P=0.004），与蛙式位视图的平均差异为 13.47°（P=0.002）。
这项实验研究证实了蛙式 45/45/30 视图在协助诊断凸轮型 FAI 中的价值。
