Department of Orthopedic Surgery and Traumatology, Freiburg University Hospital, Albert Ludwigs University Freiburg, Hugstetter Straße 55, 79106, Freiburg, Germany.
Orthopädische Klinik Paulinenhilfe, Diakonieklinikum Stuttgart, Rosenbergstr. 38, 70176, Stuttgart, Germany.
Knee Surg Sports Traumatol Arthrosc. 2022 May;30(5):1654-1660. doi: 10.1007/s00167-021-06697-3. Epub 2021 Aug 22.
Trochlear dysplasia is a significant risk factor for patellofemoral instability. The severity of trochlear dysplasia is commonly evaluated based on the Dejour classification in axial MRI slices. However, this often leads to heterogeneous assessments. A software to generate MRI-based 3D models of the knee was developed to ensure more standardized visualization of knee structures. The purpose of this study was to assess the intra- and interobserver agreements of 2D axial MRI slices and an MRI-based 3D software generated model in classification of trochlear dysplasia as described by Dejour.
Four investigators independently assessed 38 axial MRI scans for trochlear dysplasia. Analysis was made according to Dejour's 4 grade classification as well as differentiating between 2 grades: low-grade (types A + B) and high-grade trochlear dysplasia (types C + D). Assessments were repeated following a one-week interval. The inter- and intraobserver agreement was determined using Cohen's kappa (κ) and Fleiss kappa statistic (κ). In addition, the proportion of observed agreement (po) was calculated for assessment of intraobserver agreement.
The assessment of the intraobserver reliability with regard to the Dejour-classification showed moderate agreement values both in the 2D (κ = 0.59 ± 0.08 SD) and in the 3D analysis (κ = 0.57 ± 0.08 SD). Considering the 2-grade classification, the 2D (κ = 0.62 ± 0.12 SD) and 3D analysis (κ = 0.61 ± 0.19 SD) each showed good intraobserver matches. The analysis of the interobserver reliability also showed moderate agreement values with differences in the subgroups (2D vs. 3D). The 2D evaluation showed correspondences of κ = 0.48 (Dejour) and κ = 0.46 (high / low). In the assessment based on the 3D models, correspondence values of κ = 0.53 (Dejour) and κ = 0.59 (high / low) were documented.
Overall, moderate-to-good agreement values were found in all groups. The analysis of the intraobserver reliability showed no relevant differences between 2 and 3D representation, but better agreement values were found in the 2-degree classification. In the analysis of interobserver reliability, better agreement values were found in the 3D compared to the 2D representation. The clinical relevance of this study lies in the superiority of the 3D representation in the assessment of trochlear dysplasia, which is relevant for future analytical procedures as well as surgical planning.
Level II.
滑车发育不良是髌股不稳定的一个重要危险因素。滑车发育不良的严重程度通常基于矢状面 MRI 切片中的 Dejour 分类进行评估。然而，这往往会导致评估结果不一致。为了确保更标准化地可视化膝关节结构，开发了一种基于 MRI 的膝关节 3D 模型生成软件。本研究的目的是评估 2 名观察者在评估 Dejour 描述的滑车发育不良时，对 2D 轴位 MRI 切片和基于 MRI 的 3D 软件生成模型的组内和组间一致性。
4 名研究者独立评估了 38 例轴位 MRI 扫描的滑车发育不良情况。分析采用 Dejour 4 级分类进行，并区分低级别（A 型+B 型）和高级别滑车发育不良（C 型+D 型）。一周后重复评估。采用 Cohen's kappa（κ）和 Fleiss kappa 统计量（κ）评估组内和组间一致性。此外，还计算了观察一致性比例（po），以评估组内一致性。
在 Dejour 分类方面，观察者内可靠性评估的 2D 分析显示中度一致性，κ 值为 0.59±0.08 SD，3D 分析显示中度一致性，κ 值为 0.57±0.08 SD。考虑到 2 级分类，2D（κ=0.62±0.12 SD）和 3D 分析（κ=0.61±0.19 SD）均显示出良好的观察者内一致性。观察者间可靠性分析也显示出中度一致性，且在亚组间存在差异（2D 与 3D）。2D 评估显示 κ 值分别为 0.48（Dejour）和 0.46（高/低）。在基于 3D 模型的评估中，κ 值分别为 0.53（Dejour）和 0.59（高/低）。
总体而言，所有组均显示出中度至高度一致性。观察者内可靠性分析显示 2D 和 3D 表示之间没有明显差异，但 2 级分类的一致性更好。在观察者间可靠性分析中，3D 表示的一致性更好。本研究的临床意义在于，3D 表示在评估滑车发育不良方面具有优越性，这对未来的分析程序和手术计划具有重要意义。
2 级。
