Fettig Arthur A, Rand William M, Sato Amy F, Solano Mauricio, McCarthy Robert J, Boudrieau Randy J
Department of Clinical Sciences, Tufts University School of Veterinary Medicine, North Grafton, MA 01536, USA.
Vet Surg. 2003 Sep-Oct;32(5):471-8. doi: 10.1053/jvet.2003.50054.
To determine (1) the inter- and intraobserver variability in measurement of tibial plateau angle (TPA), (2) whether this inter- and intraobserver variability is related to the characteristics of the dog (age, size, and amount of degenerative joint disease [DJD]) and the experience level of the observer, and (3) the extent of any relationship between interobserver variability of TPA and the variability of the observers' selection of the specific cranial and caudal points along the tibial plateau.
Examination of tibial radiographs of 40 dogs clinically affected with a cranial cruciate ligament (CrCL)-deficient stifle joint.
Eleven different observers, divided into 3 groups based on their level of experience with the tibial plateau leveling osteotomy (TPLO) technique, measured the TPA on all 40 radiographs on 5 different occasions. The degree of DJD present in the stifle joint was independently graded as an overall measure and then again as it specifically related to the cranial and caudal points along the tibial plateau. The total observed variabilities of the TPA were assessed with reference to interobserver differences, intraobserver differences, and among the groups of observers with respect to the different dog characteristics. Finally, the specific points selected on the radiographs were reexamined to determine whether any variability was present in cranial and caudal point selection.
The interobserver standard deviation of the TPA measurements for each dog was 0.8 degrees, and the intraobserver standard deviation was 1.5 degrees. The TPA measurements obtained by the 11 observers differed significantly from each other (P <.001); however, there was no significant difference of TPA among the different groups of observers (P =.67). There was no significant correlation observed between either the inter- or intraobserver variability and the dog characteristics. Specific point data and their relationship to the various variables of dog characteristics and inter- and intraobserver TPA variability revealed significant correlations only to the amount of DJD present at the caudal point (P =.001).
Interobserver variation, but no significant group variation, was present. Overall DJD did not appear to be related to the variability in TPA angle measurement. Most of the interobserver variability was attributable to variability in horizontal point selection at both the cranial and caudal points and vertical point selection at the caudal point. It appears that degenerative changes that specifically obscure the points on the tibial plateau, especially at the caudal point, are responsible for most of the interobserver variation.
The desired postoperative TPA of 5 degrees is dependent on a precise initial measure of TPA preoperatively. This study indicates that there is statistically significant interobserver variability with measurement of TPA, which, therefore, can result in a similar amount of variability with the final tibial plateau slope obtained postoperatively.
确定（1）胫骨平台角（TPA）测量的观察者间和观察者内变异性；（2）这种观察者间和观察者内变异性是否与犬的特征（年龄、体型和退行性关节病[DJD]的程度）以及观察者的经验水平相关；（3）TPA的观察者间变异性与观察者沿胫骨平台选择特定颅侧和尾侧点的变异性之间的任何关系程度。
对40只临床患有颅侧十字韧带（CrCL）缺失的 stifle关节的犬的胫骨X线片进行检查。
11名不同的观察者，根据他们对胫骨平台水平截骨术（TPLO）技术的经验水平分为3组，在5个不同时间对所有40张X线片测量TPA。独立地将stifle关节中存在的DJD程度作为总体测量进行分级，然后再次将其与沿胫骨平台的颅侧和尾侧点具体相关联进行分级。参照观察者间差异、观察者内差异以及不同犬特征组的观察者间差异，评估TPA的总观察变异性。最后，重新检查X线片上选择的特定点，以确定颅侧和尾侧点选择中是否存在任何变异性。
每只犬TPA测量的观察者间标准差为0.8度，观察者内标准差为1.5度。11名观察者获得的TPA测量值彼此有显著差异（P <.001）；然而，不同观察者组之间的TPA没有显著差异（P =.67）。在观察者间或观察者内变异性与犬的特征之间未观察到显著相关性。特定点数据及其与犬特征的各种变量以及观察者间和观察者内TPA变异性的关系仅显示与尾侧点处存在的DJD程度有显著相关性（P =.001）。
存在观察者间差异，但无显著的组间差异。总体DJD似乎与TPA角度测量的变异性无关。大多数观察者间变异性归因于颅侧和尾侧点的水平点选择以及尾侧点的垂直点选择的变异性。似乎特别是使胫骨平台上的点模糊不清的退行性变化，尤其是在尾侧点，是大多数观察者间差异的原因。
期望术后TPA为5度取决于术前对TPA的精确初始测量。本研究表明，TPA测量存在统计学上显著的观察者间变异性，因此，这可能导致术后获得的最终胫骨平台斜率有类似程度的变异性。
