计算机断层扫描量化伴有J形征的异常髌骨轨迹

Quantification of Patellar Maltracking Combined with J-Sign Using Computed Tomography

目的:利用计算机断层扫描(computed tomography,CT)定量评估伴有J形征的异常髌骨轨迹。方法:本研究为回顾性研究,共纳入53名被诊断为复发性髌骨脱位成年患者,术前嘱患者主动屈伸膝关节,并由两名高年资医师评估髌骨轨迹,根据J形征的有无将患者分为A组(J形征阳性组)和B组(J形征阴性组)。此外,所有患者术前均在伸膝0°位状态下行膝关节CT扫描,并于横断位分别测量髌骨平分指数(bisect offset index,BOI),髌骨外侧位移指数(patellar trochlear-groove distance,PTG)及髌骨外侧倾斜角(patellar lateral tilt,PLT)。最后,比较J形征阳性组与J形征阴性组间的CT测量指数是否存在显著性差异,并利用ROC曲线进一步分析并对比三种参数量化J形征的准确性及稳定性。结果:53例患者中,共有37例(69.8%)呈现J形征阳性,其余16例(30.2%)患者均未见J形征。J形征阳性组患者BOI、PTG及PLT平均值均显著大于J形征阴性组患者。在区分J形征阳性与否的三个指标中,其曲线下面积(AUC)分别为AUC_(BOI)=0.906,AUC_(PTG)=0.883,AUC_(PLT)=0.833,其中BOI的灵敏度为83.3%,特异度为87.5%,cut-off预测值为97.5%。结论:在本研究中53例复发性髌股关节不稳定患者中,近端髌骨轨迹异常(J形征)的发生率为69.8%。可利用CT参数BOI,较好地区分J形征阳性与阴性患者。

Objective To quantify the patellar mal-tracking combined with J-sign using the computed tomography （CT）.Method Fifty-three adult patients diagnosed as recurrent patellar dislocation （RPD） were chosen.According to their patellar tracking during knee active flexion and extension,they were divided into group A （with positive J-sign） and group B （with negative J-sign）.The CT examinations were performed in all patients at 0° extension of the knee and the patella bisect offset index （BOI）,patella trochlear-groove distance （PTG） and patella lateral tilt （PLT） were measured in the axial position and compared.The receiver operating characteristic analysis （ROC） curve was used to analyse the accuracy and stability of the three J-sign parameters.Results In all the 53 patients,thirty-seven （69.8%） knees were of positive J-sign,while the rest 16 were of negative J-sign.The mean values of CT parameters BOI,PTG and PLT in group A were significantly larger than those of group B.Moreover,the area under the curve for BOI,PTG and PLT were 0.906,0.883 and 0.833 respectively.The sensitivity and specificity of BOI were 83.3% and 87.5%,while the predicting cut-off value was97.5%.Conclusion In all the 53 recurrent patella instability patients,the morbidity of patella proximal mal-trackingis 69.8%.The CT parameter BOI can be used to quantify the J-Sign into positive and negative groups.