Department of Radiology.
Department of Physiotherapy, Royal Hospital for Sick Children.
J Pediatr Orthop B. 2020 May;29(3):219-227. doi: 10.1097/BPB.0000000000000709.
The aim of this study was to determine the relationship of tangent to the lateral roof angle (TLRA), Graf's alpha angle and percentage femoral head cover (PHC) and to observed stability, and to establish intraobserver and interobserver errors for measurement of alpha angle and TLRA. In total, 2235 babies referred to the hip review clinic over a period of 8 years. Intraobserver and interobserver errors were calculated from readings of 383 hip images by an experienced paediatric radiologist and a trainee. Taking TLRA <70° as abnormal resulted in sensitivity for unstable right hips of 88% compared with 77% for alpha angle <60° (P = 0.002) and 81% for PHC <60% (P = 0.028) and specificity of TLRA 89%, alpha angle 90% (P = 0.07) and PHC 83% (P < 0.001). Corresponding figures for left hips are sensitivity of TLRA 99%, alpha angle 91% (P < 0.001) and PHC 96% (P = 0.013), and specificity TLRA 86%, alpha angle 83% (P = 0.001) and PHC 67% (P < 0.001). Mean intraobserver errors for alpha angle were 1.85° and 1.81° for consultant and trainee compared to 2.54 and 2.55 for TLRA. Mean interobserver errors were 2.22 for alpha angle and 3.42 for TLRA. TLRA, a new parameter, correlated better with observed stability with significant improvement in sensitivity in both hips and specificity in left hips compared with Graf's alpha angle, and significantly improved sensitivity and specificity in both hips compared with percentage femoral head cover.
本研究旨在确定切线至外侧顶角度（TLRA）、Graf α 角和股骨头覆盖率（PHC）之间的关系，并观察其稳定性，同时评估测量 α 角和 TLRA 的观察者内和观察者间误差。在 8 年的时间里，共有 2235 名婴儿在髋关节复查门诊就诊。由一位经验丰富的儿科放射科医生和一名受训者对 383 张髋关节图像进行了读数，计算出了观察者内和观察者间误差。将 TLRA<70°视为异常，与 α 角<60°（P=0.002）和 PHC<60%（P=0.028）相比，右侧髋关节不稳定的敏感性分别为 88%、77%和 81%，而 TLRA 的特异性为 89%、α角为 90%（P=0.07）和 PHC 为 83%（P<0.001）。对于左侧髋关节，TLRA 的敏感性为 99%、α角为 91%（P<0.001）和 PHC 为 96%（P=0.013），特异性为 TLRA 为 86%、α角为 83%（P=0.001）和 PHC 为 67%（P<0.001）。顾问和受训者测量 α 角的观察者内误差平均值分别为 1.85°和 1.81°，而 TLRA 的平均值分别为 2.54°和 2.55°。测量 α 角的观察者间误差平均值为 2.22°，TLRA 的平均值为 3.42°。TLRA 是一个新的参数，与观察到的稳定性相关性更好，与 Graf α 角相比，双侧髋关节的敏感性均显著提高，左侧髋关节的特异性也显著提高，与股骨头覆盖率相比，双侧髋关节的敏感性和特异性均显著提高。
