Hospital for Special Surgery, 535 E. 70th Street, New York, NY 10021, USA.
Clin Orthop Relat Res. 2012 Oct;470(10):2810-8. doi: 10.1007/s11999-012-2292-9. Epub 2012 Mar 1.
Although cross-table lateral radiographs are commonly used to measure acetabular component version after THA, recent studies suggest that CT-based measurement is more accurate. This has been attributed to variations in pelvic tilt, pelvic rotation, and component inclination. Furthermore, it has been suggested, based on limited data, that even with ideal positioning of the cross-table lateral radiograph, CT remains the more accurate modality.
QUESTIONS/PURPOSES: We determined whether appropriately positioned cross-table lateral radiographs could provide accurate measurements of acetabular component version, and compared accuracy and reliability of measurements from modified cross-table lateral radiographs with those from standard cross-table lateral radiographs and CT.
We implanted 27 Sawbones pelves with an acetabular cup using computer navigation. CT, an AP view of the pelvis, and cross-table lateral and modified cross-table lateral radiographs were performed for each specimen. For the modified cross-table lateral radiograph, the beam angle varied based on the cup inclination as measured on an AP view of the pelvis. Two independent observers measured acetabular component version and inclination. We calculated intraobserver and interobserver reliabilities for each method and compared these with values obtained from navigation presuming that to be the standard for judging accuracy.
Interobserver and intraobserver reliabilities were greater than 0.95 (95% CI, 0.904-0.999) for all measurements. Correlation with navigated values was 0.96 or greater (95% CI, 0.925-0.998) for all methods. Although CT had the highest correlation with navigated values, the correlations for the modified cross-table lateral and cross-table lateral radiographs were similar.
CT allows for accurate measurement of acetabular component version; however, when properly positioned, cross-table lateral radiograph-derived measurements are similarly accurate.
Our results support the use of plain radiographs to obtain important measurements after THA.
尽管髋关节置换术后髋臼假体版本的测量通常采用骨盆侧位 X 线片，但最近的研究表明，基于 CT 的测量更为准确。这归因于骨盆倾斜、骨盆旋转和假体倾斜的变化。此外，基于有限的数据，有人认为即使骨盆侧位 X 线片的定位理想，CT 仍然是更准确的模式。
问题/目的：我们确定了适当定位的骨盆侧位 X 线片是否可以提供髋臼假体版本的准确测量值，并比较了改良骨盆侧位 X 线片、标准骨盆侧位 X 线片和 CT 的测量值的准确性和可靠性。
我们使用计算机导航将 27 个 Sawbones 骨盆植入髋臼杯。对每个标本进行 CT、骨盆正位 X 线片、骨盆侧位和改良骨盆侧位 X 线片检查。对于改良骨盆侧位 X 线片，根据骨盆正位 X 线片上测量的杯倾斜角度改变射线束角度。两名独立观察者测量髋臼假体的版本和倾斜度。我们计算了每种方法的观察者内和观察者间的可靠性，并将其与导航假定的标准值进行了比较，以判断准确性。
所有测量的观察者内和观察者间可靠性均大于 0.95（95%置信区间，0.904-0.999）。所有方法与导航值的相关性均为 0.96 或更高（95%置信区间，0.925-0.998）。尽管 CT 与导航值的相关性最高，但改良骨盆侧位 X 线片和骨盆侧位 X 线片的相关性相似。
CT 可用于准确测量髋臼假体的版本；然而，当正确定位时，骨盆侧位 X 线片的测量值同样准确。
我们的结果支持在髋关节置换术后使用普通 X 线片获得重要的测量值。
