Department of Orthopaedic Medical Engineering, Osaka University Graduate School of Medicine, Suita, Osaka, Japan.
Graduate School of Information Science, Nara Institute of Science and Technology, Ikoma, Nara, Japan.
J Arthroplasty. 2018 Feb;33(2):595-600. doi: 10.1016/j.arth.2017.09.027. Epub 2017 Sep 21.
Stem anteversion angle is important in the combined anteversion theory to avoid implant impingement after total hip arthroplasty (THA). However, anatomic measurements of stem anteversion angle may not represent functional anteversion of the femur if the femur undergoes axial rotation. Herein, the femoral rotational angle (FRA) was measured in supine and standing positions before and after THA to evaluate the difference between anatomic and functional measurements.
A total of 191 hips (174 patients) treated with THA for osteoarthritis were analyzed in this retrospective, case-controlled study. The FRA was measured as the angle between the posterior condylar line and the line through the bilateral anterior superior iliac spines (positive for external rotation) and was measured preoperatively and postoperatively in supine and standing positions with computed tomography segmentation and landmark localization of the pelvis and the femur followed by intensity-based 2D-3D registration. The number of cases in which the absolute FRA remained <15° in both positions was also calculated.
The average ± standard deviation preoperative FRA was 0.3° ± 8.3° in the supine position and -4.5° ± 8.8° during standing; the postoperative FRA was -3.8° ± 9.0° in supine and -14.3° ± 8.3° during standing. There were 134 cases (70%) in which the preoperative absolute FRA remained <15° in both positions while only 85 hips (45%) remained <15°, postoperatively.
Substantial variability was seen in the FRA, especially during the postoperative period. These results suggest that the anatomic stem anteversion angle may not represent the functional anteversion of the femur.
在全髋关节置换术（THA）后避免假体撞击的综合前倾角理论中，股骨前倾角很重要。然而，如果股骨发生轴向旋转，那么股骨前倾角的解剖学测量可能无法代表股骨的功能性前倾角。在此，通过测量 THA 前后仰卧位和站立位的股骨旋转角（FRA），来评估解剖学测量与功能性测量之间的差异。
本回顾性病例对照研究共分析了 191 髋（174 例患者）因骨关节炎接受 THA 治疗的病例。FRA 定义为后髁线与双侧髂前上棘连线（外旋为正）之间的夹角，通过骨盆和股骨的 CT 分割及标志点定位，在术前及术后仰卧位和站立位进行测量，然后进行基于强度的 2D-3D 配准。还计算了两种体位下绝对 FRA 均<15°的病例数。
仰卧位时，术前平均（标准差）FRA 为 0.3°（8.3°），站立位时为-4.5°（8.8°）；术后仰卧位 FRA 为-3.8°（9.0°），站立位时为-14.3°（8.3°）。术前两种体位下绝对 FRA 均<15°的病例有 134 例（70%），而术后仅有 85 髋（45%）符合这一标准。
FRA 变化较大，尤其是在术后阶段。这些结果表明，解剖学上的股骨前倾角可能无法代表股骨的功能性前倾角。
