探讨Cam型髋撞击辐射状层面α角的诊断价值

To Investigate The Alpha Angle Of Cam Type Femoro-Acetabular Impingement(FAI) Estimated by Means of the Multiple Radial Plane Protocol

目的探讨Cam型髋关节撞击患者α角在股骨头颈不同层面的诊断价值。方法选取临床诊断为Cam型髋撞击患者30例,另选取与病例组年龄相近,性别相同的30例患者为对照组,行CT扫描后重组各斜轴位及辐射状层面,并测量其α角,所得数据采用单因素方差分析,多重比较采用LSD法,并绘制其ROC曲线。结果对照组各层面α角进行比较,差异无统计学意义(P>0.05)。病例组斜轴位α角均值为(52.56±0.86)°,共有23侧髋关节>55°,占受试者的46%(23/50);在辐射状层面中12点、1点、2点、3点方向所得α角均值分别为(56.65±0.92)°、(66.34±1.21)°、(64.93±1.20)°、(52.70±0.86)°,共148侧髋关节α角>55°。其中1点、2点方向α角平均值明显大于其他各组,在该方向各有43~44侧髋关节α角>55°,占所有受试者的86%~88%。各层面α角进行比较,差异具有统计学意义(F=42.875,P<0.01),LSD比较结果显示,除1点与2点方向、斜轴位与3点方向差异无统计学意义外,其他各两组间均有统计学差异(P均<0.01)。病例组各层面ROC曲线下面积分别为0.959、0.981、0.996、0.998、0.966,各层面诊断界值分别为44.05°~45.57°、46.77°~48.72°、51.48°~52.22°、49.94°~51.91°、42.33°~43.79°,其中12点、1点及2点方向的敏感度及特异度均>90%。较传统斜轴位诊断阈值(50°或55°)相比,其敏感度及特异度均较高。结论辐射状层面对股骨头颈交界区前上方形态改变显示更加敏感,α角诊断性仍需进行大样本探讨,从而设定较合理的诊断阈值。

Objective To investigate the alpha angle of cam type femoro-acetabular impingement（FAI） estimated by means of the oblique axial and multiple radial plane protocols which were compared with the computed results.Methods30 cases with clinical diagnosis of cam type FAI were treated as the case group and the other 30 cases with asymptomatic presentations were treated as the control group.Hip joint MSCT scan and three-dimensional reconstruction were performed to assess the images of the oblique axial and multiple radial plane protocol.The data was tested by ANOVA test to draw the receiver operating characteristic（ROC） curve.Results The value of alpha angle of Cam-type on the control group was of no statistical significance（P 0.05）.The mean value of the alpha angle of the case group on the oblique axial plane was（52.56 ± 0.86） °.Alpha angle greater than 55° was found in 50 joints of 23 cases（46%,23/50）.The mean alpha angle values at the 12,1,2,3 o＇clock position were（56.65 ± 0.92） °,（66.34 ± 1.21） °,（64.93 ± 1.20） °,（52.70 ± 0.86） °,respectively.148 Alpha angle greater than 55° in total were found on the radial plane images.The mean alpha angle values at the 1 and 2 o＇clock position were greater than others.The Alpha angle greater than 55° in total were found at the 1 and2 o＇clock position,including 86%-88%（43-44/50） of the subjects.Significant statistical differences were found between the oblique axial and multiple radial plane protocols in the case group in the alpha angle value（P 0.05）.Multiple comparisons demonstrate that except result between the value of alpha angle on the 1 o＇clock and 2 o＇clock,oblique axial and 3 o＇clock,the others were statistically significant.The areas under receiver operating characteristic（ROC） curve of the alpha angle on the oblique axial and multiple radial plane protocol were 0.959,0.981,0.996,0.998,0.966,respectively.The diagnostic threshold values of the different levels were 44.05-45.57°,46.77-48.72°,51.48-52.22°,49.94-51.91°,42.33-43.79°,respectively.The sensitivity and the specificity were greater than 90° in 12,1,2 o＇clock position,which were greater than the oblique axial plane（50°or 55°）.Conclusion The morphological changes of the femoral head-neck junction were more sensitive on the multiple radial plane protocol.The diagnosis of the alpha angle has to be explored with a large sample,so as to set a more reasonable diagnostic threshold.