Department of Orthopaedics Surgery, Niigata University Medical and Dental Hospital, 1-757 Asahimachidori, Niigata, Japan.
Clin Orthop Relat Res. 2013 Apr;471(4):1271-6. doi: 10.1007/s11999-012-2700-1. Epub 2013 Jan 3.
Pelvic flexion affects orientation of the acetabular cup; however, pelvic position is not static in daily activities. During THA it is difficult to know the degree of pelvic flexion with the patient in the lateral position and that position is static. However, surgeons need to appropriately determine pelvic tilt to properly insert the acetabular component.
QUESTIONS/PURPOSES: We investigated the reliability of pelvic flexion angle that was measured by manually identifying the location of the pubic symphysis and bilateral anterior superior iliac spines using synthesized lateral radiographs.
We synthesized 49 lateral radiographs based on CT data. Each of the 49 radiographs had a unique position: 7° of varying lateral tilt and rotation in each of seven selected pelvic flexion angles. The pelvic flexion angle was measured three times by three independent observers in each position and determined the accuracy (based on the true value from the reconstructions) and reliability of the measures.
The measurement error was 0.1° (range, -4.8° to 4.0°). There was a tendency for errors when the pelvic flexion angle was 0° or ±5°; the errors were less when the pelvic flexion angle was ±10° or ±20°. Lateral tilt was associated with greater error than rotation. The intraclass correlation coefficient (ICC) of the average value was 0.967. For one observer, more than two measurements are necessary for the ICC to be greater than 0.8, and only one measurement was needed for two of the three observers.
Our data suggest measurement of pelvic flexion angle using lateral radiographs is reliable. We recommend the measurement be performed once by two observers for better reliability.
骨盆前倾会影响髋臼杯的方向；然而，骨盆在日常活动中的位置并非固定不变。在全髋关节置换术中，很难在患者处于侧卧位且该位置为静态时确定骨盆前倾的程度。但是，外科医生需要适当确定骨盆倾斜度，以便正确插入髋臼部件。
问题/目的：我们研究了使用合成侧位 X 光片手动识别耻骨联合和双侧髂前上棘位置来测量骨盆前倾角度的可靠性。
我们根据 CT 数据合成了 49 张侧位 X 光片。每张 X 光片都有一个独特的位置：在七个选定的骨盆前倾角度中的每个角度上，倾斜度和旋转度各有 7°的变化。在每个位置，三位独立观察者对骨盆前倾角度进行了三次测量，并确定了测量的准确性（基于重建的真实值）和可靠性。
测量误差为 0.1°（范围，-4.8°至 4.0°）。骨盆前倾角度为 0°或±5°时，误差有增大的趋势；骨盆前倾角度为±10°或±20°时，误差较小。倾斜度比旋转度的误差更大。平均值的组内相关系数（ICC）为 0.967。对于一位观察者，要使 ICC 大于 0.8，需要进行两次以上测量，而对于三位观察者中的两位，仅需进行一次测量。
我们的数据表明，使用侧位 X 光片测量骨盆前倾角度是可靠的。我们建议由两位观察者进行一次测量，以提高可靠性。
