术前膝关节剥脱性骨软骨炎分级及稳定性的磁共振成像评估

Preoperative Evaluation of the Grade and Stability of Osteochondritis Dissecans of the Knee by Magnetic Resonance Imaging

目的评价磁共振(MR)成像检查评估膝关节剥脱性骨软骨炎(OCD)分级及稳定性的能力。方法由2名放射诊断医师独立回顾性分析47例经关节镜证实的膝关节OCD患者的术前MR图像,按照OCD国际软骨修复协会分类标准将OCD病变分成4级,与关节镜结果进行对照,计算MR评价OCD稳定性的特异度、敏感度和准确度,计算Kappa值,评价2名医师之间MR诊断OCD分级的一致性。计算提示膝关节OCD不稳定的MR征象诊断不稳定OCD的特异度、敏感度及准确度。结果 47例患者中,48个OCD病灶,Ⅰ、Ⅱ、Ⅲ、Ⅳ级OCD分别为4、8、16、20例,2名医师MR术前诊断OCD稳定性的特异度、敏感度、准确度分别为75.0%(83.3%)、88.9%(86.1%)、85.4%(85.4%),2名医师诊断OCD分级的一致性较好(Kappa=0.82)。提示膝关节OCD不稳定的MR征象:病灶与母体骨交界面线状高信号、病灶邻近骨质多发囊变影或出现大囊变(直径>5 mm)、累及全层的软骨骨折线、累及全层的软骨缺损诊断膝关节OCD稳定性的特异度、敏感度、准确度分别为83.3%、80.6%、81.3%;75.0%、72.2%、72.9%;66.7%、69.4%、68.8%;100%、86.1%、89.6%。结论软骨缺损是诊断不稳定OCD最特异的MR征象,而软骨骨折线的准确率最低。膝关节MR检查是评价OCD稳定性及分级比较可靠的方法。

Objective To assess the diagnostic performance of magnetic resonance imaging（MRI） in the grading of osteochondritis dissecans（OCD） of the knee.Methods Totally 47 patients with OCD of the knee confirmed by arthroscopy were retrospectively enrolled in this study.The OCD lesions were classified into four stages according to classification system of the International Cartilage Repair Society.Two radiologists analyzed all MRI findings independently,and the results were compared with those of arthroscopy.Sensitivity,specificity,and accuracy were calculated.Kappa value were calculated to quantify inter-observer agreement of the diagnostic OCD grade between two doctors by MRI.Specificity,sensitivity,and accuracy of MRI criteria indicating instability for detection of OCD instability were calculated.Results Of these 47 patients with 48 OCD lesions,stagesⅠ,Ⅱ,Ⅲ,and Ⅳ lesions were detected in 4,8,16,and 20 patients,respectively.The specificity,sensi-tivity,and accuracy for the diagnosis of OCD stability were 75.0%（83.3%）,88.9%（86.1%）,and 85.4%（85.4%） for observer l（2）,and the agreement of OCD grade between these two readers was substantial with a Kappa value of 0.82.The specificity,sensitivity,and accuracy of MRI criteria for the detection of OCD instability including high T2 signal intensity at the interface between the OCD and the underlying bone,multiple cysts or a single cyst of5 mm in diameter surrounding OCD lesions,high T2 signal intensity cartilage fracture line traversing the articular cartilage,and osteochondral defect were 83.3%,80.6%,and 81.3%;75.0%,72.2%,and 72.9%;66.7%,69.4%,and 68.8%;100%,86.1%,and 89.6%,respectively.Conclusions Osteochondral defect is the most specific MRI sign for diagnosing instable OCD of the knee,whereas osteochondral fracture line has the lowest accuracy.MRI is a useful method to evaluate the grade and stability of OCD of the knee.