Department of Orthopaedic Surgery, Washington University School of Medicine, 660 S Euclid, 11300 West Pavilion, Campus Box 8233, St Louis, MO, USA.
Clin Orthop Relat Res. 2012 Dec;470(12):3313-20. doi: 10.1007/s11999-012-2510-5.
Three-dimensional imaging (CT and MRI) is the gold standard for detecting femoral head-neck junction malformations in femoroacetabular impingement, yet plain radiographs are used for initial diagnostic evaluation. It is unclear, however, whether the plain radiographs accurately reflect the findings on three-dimensional imaging.
QUESTIONS/PURPOSES: We therefore: (1) investigated the correlation of alpha angle measurements on plain radiographs and radial reformats of CT scans; (2) determined which radiographic views are most sensitive and specific in detecting head-neck deformities present on CT scans; and (3) determined if specific radiographic views correlated with specific locations on the radial oblique CT scan.
We retrospectively reviewed 41 surgical patients with preoperative CT scans (radial oblique reformats) and plain radiographs (AP pelvis, 45° Dunn, frog lateral, and crosstable lateral). Alpha angles were measured on plain radiographs and CT reformats.
The complete radiographic series was 86% to 90% sensitive in detecting abnormal alpha angles on CT. The maximum alpha angle on plain radiographs was greater than that of CT reformats in 61% of cases. Exclusion of the crosstable lateral did not affect the sensitivity (86%-88%). The Dunn view was most sensitive (71%-80%). The frog lateral showed the best specificity (91%-100%). Substantial correlations (intraclass correlation coefficients, 0.64-0.75) between radiograph and radial oblique CT position were observed, including AP/12:00 (superior), Dunn/1:00 (anterolateral), frog/3:00 (anterior), and crosstable/3:00 (anterior).
For diagnostic and treatment purposes, a three-view radiographic hip series (AP pelvis, 45° Dunn, and frog lateral) effectively characterizes femoral head-neck junction malformations.
Level II, diagnostic study. See Guidelines for Authors for a complete description of levels of evidence.
三维成像（CT 和 MRI）是检测股骨髋臼撞击症中股骨头颈交界处畸形的金标准，但初始诊断评估仍使用平片。然而，目前尚不清楚平片是否准确反映三维成像的结果。
问题/目的：因此，我们：（1）研究了平片上 α 角测量值与 CT 扫描的放射状重建之间的相关性；（2）确定了在 CT 扫描上检测到头颈畸形的最敏感和最特异的放射学视图；（3）确定了特定的放射学视图是否与放射状斜位 CT 扫描的特定位置相关。
我们回顾性分析了 41 例术前 CT 扫描（放射状斜位重建）和平片（骨盆正位、45°Dunn、蛙式侧位和交叉侧位）的手术患者。在平片和 CT 重建上测量 α 角。
完整的放射学系列在检测 CT 上异常 α 角方面的敏感性为 86%至 90%。在 61%的病例中，平片上的最大 α 角大于 CT 重建上的 α 角。排除交叉侧位不影响敏感性（86%-88%）。Dunn 视图最敏感（71%-80%）。蛙式位显示出最佳的特异性（91%-100%）。放射学与放射状斜位 CT 位置之间存在显著相关性（组内相关系数，0.64-0.75），包括骨盆正位/12:00（上）、Dunn/1:00（前外侧）、蛙式/3:00（前）和交叉侧位/3:00（前）。
对于诊断和治疗目的，三视射线髋关节系列（骨盆正位、45°Dunn 和蛙式位）可有效描述股骨头颈交界处畸形。
Ⅱ级，诊断研究。请参阅作者指南以获取完整的证据等级描述。
