Department of orthopaedic surgery, North Hospital, Marseille, France.
Orthop Traumatol Surg Res. 2009 Dec;95(8):568-72. doi: 10.1016/j.otsr.2009.08.004.
Most computer-assisted navigation systems used in total hip arthroplasty (THA) reference the anterior pelvic plane, which connects the anterior superior iliac spines and the pubic symphysis. The pelvic tilt is defined as the angle between this anterior pelvic plane (APP) and a vertical line in the standing position. Important interindividual variations of this angle have been reported and may affect final functional anteversion of the acetabular cup. The preoperative value of the pelvic tilt has been included in computer-assisted navigation systems to improve acetabular cup positioning. However, there is no data available which strongly confirms the consistency of this angle for each individual after hip prosthesis implantation.
The orientation of the APP in the standing position is not significantly modified after THA.
To evaluate in a prospective manner, the reproducibility of pelvic tilt measurement and its variability between THA preoperative and 3-year postoperative measurements.
A lateral teleradiograph of the pelvis and dorsolumbar spine was obtained in the standing position preoperatively and 3 years after THA. Fifty patients undergoing THA performed by a single operator via an anterolateral approach (26 males and 24 females) were included prospectively. The pelvic tilt was measured on radiographs by two independent observers. The angle was defined as positive in case of pelvis retroversion relative to the vertical plane and negative in case of anteversion. Bland-Altman analysis was used to assess levels of agreement between both operator measurements while preoperative and last follow-up measurements were compared using the Student t-test for unpaired samples.
The level of agreement between measurements of both operators was satisfactory. Mean preoperative pelvic tilt was 4.68 degrees +/-0.68 S.D. (-6 degrees to 14 degrees), and 4.78 degrees +/-0.64 S.D. (-5 degrees to 14 degrees) at last follow-up. The mean difference between preoperative and last follow-up measurements was 3 degrees +/-0.3 S.D. There was no statistically significant variation between preoperative and 3-year follow-up values (p>0.05). Ninety-five percent of the patients had less than a 5 degrees difference between both measurements while 5% had a difference ranging from 5 degrees to 10 degrees ; none of the patients reported a variation greater than 10 degrees .
Our findings show no significant variation in pelvic tilt between preoperative and 3-year follow-up values after THA. Therefore, the individual preoperative value of this angle should be integrated to achieve proper acetabular cup placement during THA especially when using computed assisted navigation based on the APP.
大多数用于全髋关节置换术（THA）的计算机辅助导航系统都参考了前骨盆平面，该平面连接了前上髂嵴和耻骨联合。骨盆倾斜度定义为该前骨盆平面（APP）与站立位垂直线之间的夹角。已经报道了该角度的重要个体间差异，并且可能影响髋臼杯的最终功能前倾角。术前骨盆倾斜度已被纳入计算机辅助导航系统，以改善髋臼杯的定位。然而，目前尚无数据证实该角度在髋关节假体植入后对每个人的一致性。
THA 后，站立位 APP 的方向不会显著改变。
前瞻性评估 THA 术前和术后 3 年测量的骨盆倾斜度的可重复性及其变异性。
前瞻性纳入了 50 名由同一位术者通过前外侧入路行 THA 的患者（26 名男性和 24 名女性）。在术前和 THA 后 3 年时获得了骨盆和腰骶脊柱的侧位 X 线片。通过两位独立观察者在 X 线片上测量骨盆倾斜度。如果骨盆相对于垂直平面向后旋转，则角度为正，如果骨盆向前旋转，则角度为负。使用 Bland-Altman 分析评估两位操作者测量结果之间的一致性水平，同时使用配对样本 t 检验比较术前和末次随访测量结果。
两位操作者测量结果的一致性水平令人满意。术前平均骨盆倾斜度为 4.68 度 +/-0.68 标准差（-6 度至 14 度），末次随访时为 4.78 度 +/-0.64 标准差（-5 度至 14 度）。术前与末次随访测量结果之间的平均差值为 3 度 +/-0.3 标准差。术前与 3 年随访值之间无统计学显著差异（p>0.05）。95%的患者在两次测量之间的差值小于 5 度，5%的患者差值在 5 度至 10 度之间，没有患者报告差值大于 10 度。
我们的发现表明，THA 后，术前与 3 年随访时骨盆倾斜度无显著差异。因此，在进行 THA 时，特别是在使用基于 APP 的计算机辅助导航时，应将该角度的个体术前值纳入其中，以实现髋臼杯的正确放置。
