Division of Sports Medicine, Department of Orthopaedic Surgery, Boston Children's Hospital.
Harvard Medical School, Boston, MA.
J Pediatr Orthop. 2022;42(5):e486-e491. doi: 10.1097/BPO.0000000000002111.
The novel Kocher classification is a 3-group magnetic resonance imaging (MRI) classification system for osteochondritis dissecans (OCD) of the knee that was shown to have comparable reliability to that of the established 5-group Hefti classification. The purpose of this study was to evaluate the validity and clinical utility of this simplified system as an alternative to the Hefti classification.
Demographic data and arthroscopic findings were retrospectively collected from medical and surgical records of 144 consecutive knees in children with arthroscopically diagnosed knee OCD. OCD lesions on preoperative MRIs and surgical reports (serving as the reference standard) were assessed by independent raters and assigned both a Kocher and Hefti classification. Agreement between MRI classification and arthroscopic findings for both systems was assessed using weighted kappa (kw) coefficients. Validation, accuracy, sensitivity, and specificity were measured by comparing a dichotomized Kocher classification for MRI and arthroscopy, and by estimating Cohen kappa (kc) coefficients. Agreement between arthroscopic findings and treatment type was measured using the Spearman correlation coefficient.
Inter-rater reliability between the 2 MRI raters was substantial for the Kocher classification [ka=0.66; 95% confidence interval (CI)=0.56-0.75] and moderate for the Hefti classification (ka=0.57; 95% CI=0.47-0.67). There was no difference detected in the agreement statistics for Kocher versus Hefti classifications (P=0.89). Binary agreement using dichotomized Kocher classifications was worse than the 3-group category classification. When dichotomized, combining Kocher grades 1 and 2 demonstrated moderate agreement (kc=0.41; 95% CI=0.25-0.58), and combining grades 2 and 3 demonstrated fair agreement (kc=0.34; 95% CI=0.21-0.48). There was a strong correlation between arthroscopy-based finding and treatment category for both the Kocher classification (r=0.85; 95% CI=0.80-0.89) and the Hefti classification (r=0.82; 95% CI=0.75-0.86).
The validity and clinical utility of the newer 3-group Kocher classification for knee OCD is comparable to that of the well-established 5-group Hefti classification. Both systems help determine lesion stability and characteristics on MRI, which correlate closely to arthroscopic findings. This simplified classification system, with less uncertainty, provides a foundation for further outcomes research to develop an evidence-based algorithm for effective surgical management of OCD lesions of the knee.
Level II-diagnostic study.
新的 Kocher 分类是一种用于膝关节剥脱性骨软骨炎（OCD）的 3 组磁共振成像（MRI）分类系统，其可靠性与已建立的 Hefti 分类相当。本研究旨在评估该简化系统作为 Hefti 分类替代方案的有效性和临床实用性。
回顾性收集了 144 例膝关节镜诊断为 OCD 的儿童的医疗和手术记录中的人口统计学数据和关节镜检查结果。MRI 分类和关节镜检查结果（作为参考标准）由独立的评估者评估，并分别分配 Kocher 和 Hefti 分类。使用加权 Kappa（kw）系数评估两种系统的 MRI 分类与关节镜检查结果的一致性。通过比较 MRI 和关节镜检查的二分 Kocher 分类，并估计 Cohen kappa（kc）系数，测量验证、准确性、灵敏度和特异性。使用 Spearman 相关系数测量关节镜检查结果与治疗类型之间的一致性。
两名 MRI 评估者之间的 Kocher 分类的组内一致性较高[ka=0.66；95%置信区间（CI）=0.56-0.75]， Hefti 分类的组内一致性为中度（ka=0.57；95% CI=0.47-0.67）。在 Kocher 与 Hefti 分类的一致性统计数据中未检测到差异（P=0.89）。使用二分 Kocher 分类的二元一致性差于 3 组分类。当二分化时，合并 Kocher 1 级和 2 级表现出中度一致性（kc=0.41；95% CI=0.25-0.58），合并 2 级和 3 级表现出适度一致性（kc=0.34；95% CI=0.21-0.48）。Kocher 分类（r=0.85；95% CI=0.80-0.89）和 Hefti 分类（r=0.82；95% CI=0.75-0.86）与关节镜检查结果之间均存在很强的相关性。
较新的 3 组膝关节 OCD 的 Kocher 分类的有效性和临床实用性与建立良好的 5 组 Hefti 分类相当。两种系统均有助于确定 MRI 上的病变稳定性和特征，这些特征与关节镜检查结果密切相关。这种简化分类系统，不确定性更小，为进一步开展基于结果的研究提供了基础，以制定基于证据的膝关节 OCD 病变有效治疗管理算法。
II 级诊断研究。
