Seil R, Müller B, Georg T, Kohn D, Rupp S
Orthopedic University Hospital, Homburg/Saar, Germany.
Knee Surg Sports Traumatol Arthrosc. 2000;8(4):231-6. doi: 10.1007/s001670000121.
This study evaluated the reliability and interobserver variability of five patellar height ratios as measured by two examiners on standard radiographs: Insall-Salvati (IS), modified Insall-Salvati (MIS), Blackburne-Peel (BP), Caton-Deschamps (CD), and Labelle-Laurin (LL). Plain lateral radiographs with a knee flexion angle of 20 degrees for IS, MIS, BP, and CD ratios and 90 degrees for the LL method of 22 knees of 21 patients with varying pathological knee conditions were analyzed. Statistical results revealed a low interobserver variability with high correlation coefficients (0.86 for IS, 0.82 for MIS, 0.86 for BP, 0.92 for CD, and 0.81 for LL; P > 0.3) and low mean interobserver errors. However, regarding the reliability of the radiographic results of the different methods for patella alta, baja, or norma we found varying results in 68% of the patients. In two patients the patellar height was classified as alta, norma, or baja depending on the ratio used. Regarding the definitions of patellar height used by the authors of these methods, we found the lowest number of normal patellae with the IS ratio and no patella alta for the CD ratio. The LL method revealed the highest number of patella alta. The BP ratio showed intermediate results for both patella alta and baja, being the most moderate method. This study showed that there was a good interobserver reliability for the evaluation of patellar height according to the common radiological ratios. However, the high frequency of differing results between the different radiographic ratios showed that patellar height classification as "alta," "norma," or "baja" depends heavily on the chosen index. The differing results were due mainly to the normative patellar height data and to anatomical differences. Based on these findings we recommend a ratio using the articular surface of the patella in relation to the joint line. We recommend the BP method because it revealed the lowest interobserver variability and discriminated best among the groups alta, norma, and baja.
本研究评估了两名检查者在标准X线片上测量的五个髌骨高度比值的可靠性和观察者间变异性，这五个比值分别为：Insall-Salvati（IS）、改良Insall-Salvati（MIS）、Blackburne-Peel（BP）、Caton-Deschamps（CD）和Labelle-Laurin（LL）。对21例患有不同膝关节病变患者的22个膝关节进行了分析，IS、MIS、BP和CD比值采用膝关节屈曲角度为20度的普通侧位X线片，LL法采用膝关节屈曲角度为90度的普通侧位X线片。统计结果显示观察者间变异性较低，相关系数较高（IS为0.86，MIS为0.82，BP为0.86，CD为0.92，LL为0.81；P>0.3），观察者间平均误差较低。然而，对于不同方法测量高位髌骨、低位髌骨或正常髌骨的X线片结果的可靠性，我们发现在68%的患者中结果存在差异。在两名患者中，髌骨高度根据所使用的比值被分类为高位、正常或低位。关于这些方法的作者所使用的髌骨高度定义，我们发现使用IS比值时正常髌骨的数量最少，使用CD比值时没有高位髌骨。LL法显示高位髌骨的数量最多。BP比值在高位髌骨和低位髌骨方面均显示出中间结果，是最适中的方法。本研究表明，根据常见的放射学比值评估髌骨高度时，观察者间具有良好的可靠性。然而，不同X线片比值之间结果差异的高频率表明，将髌骨高度分类为“高位”“正常”或“低位”在很大程度上取决于所选择的指标。结果差异主要归因于正常髌骨高度数据和解剖学差异。基于这些发现，我们推荐一种使用髌骨关节面与关节线关系的比值。我们推荐BP法，因为它显示出最低的观察者间变异性，并且在高位、正常和低位组之间的区分效果最佳。
