Lee Joshua K L, Sardana Vandit, White Craig, Speirs Andrew, Beaulé Paul E
1 Division of Orthopaedic Surgery, University of Ottawa, The Ottawa Hospital, Ottawa, Ontario - Canada.
Hip Int. 2014 Jul-Aug;24(4):347-54. doi: 10.5301/hipint.5000151. Epub 2014 May 26.
Accurate measurement of cup version on plain radiographs remains difficult due to the two-dimensional projection of an ellipse and difficulty obtaining reproducible radiographs.
Determine: 1) if the cup angle measured on the false profile view (FPV) could be used to determine radiographic cup version; 2) how patient positioning would affect cup angle measurement on the FPV; 3) if implant cup design affects cup angle measurement.
Three cup version positions were assessed in a sawbone: 13° (normal); 28° (excessive anteversion) and -2° (retroversion). Cup angle was measured on the FPV at five different degrees of pelvic rotation within each cup version group. Pelvic rotation was quantified using the ratio of the inter-femoral head distance measured on the FPV versus the anteroposterior radiographs (FP/AP ratio). Eighty patients (40 metal-on-polyethylene, 40 metal-on-metal) post-total hip were also assessed. Cup version was assessed with Einzel-Bild-Roentgen-Analysis software (EBRA). R2 was calculated to assess correlation between both measurement methods.
For the sawbone model, an R2 of 0.95 was obtained. For patients, overall R2 was 0.56 with an FP/AP ratio of 0.3-0.49 having an R2 of 0.72. The EBRA anteversion versus cup angle scatterplot had an R2 of 0.72 (95%CI: +/-7.8°). Subgroup analysis revealed no differences between the metal-on-poly and metal-on-metal for cup angle measurements. The intra-class coefficient for intra- and inter-observer reliability for all cases (individual and combined FP/AP groups) was 0.98 to 0.99.
The FPV cup angle measurement value provides an accurate measurement of radiographic cup anteversion with well-defined patient position parameters.
由于椭圆的二维投影以及难以获得可重复的X线片，在普通X线片上准确测量髋臼杯的外展角仍然很困难。
确定：1）在假轮廓视图（FPV）上测量的髋臼杯角度是否可用于确定X线片上的髋臼杯外展角；2）患者体位如何影响FPV上的髋臼杯角度测量；3）植入髋臼杯的设计是否会影响髋臼杯角度测量。
在人工骨模型中评估三种髋臼杯外展角位置：13°（正常）；28°（前倾角过大）和-2°（后倾）。在每个髋臼杯外展角组内，于五个不同的骨盆旋转角度下在FPV上测量髋臼杯角度。使用在FPV上测量的股骨头间距离与前后位X线片上测量的股骨头间距离之比（FP/AP比）来量化骨盆旋转。还对80例全髋关节置换术后患者（40例聚乙烯对金属，40例金属对金属）进行了评估。使用 Einzel-Bild-Roentgen-Analysis软件（EBRA）评估髋臼杯外展角。计算R2以评估两种测量方法之间的相关性。
对于人工骨模型，获得的R2为0.95。对于患者，总体R2为0.56，FP/AP比为0.3 - 0.49时R2为0.72。EBRA前倾角与髋臼杯角度散点图的R2为0.72（95%CI：±7.8°）。亚组分析显示，聚乙烯对金属和金属对金属在髋臼杯角度测量方面无差异。所有病例（个体和合并的FP/AP组）观察者内和观察者间可靠性的组内相关系数为0.98至0.99。
FPV髋臼杯角度测量值可在明确的患者体位参数下准确测量X线片上的髋臼杯前倾角。
