肩关节不稳定的肩盂骨缺损评估：肩盂下部圆心的确定

Evaluation of glenoid bone defects in anterior shoulder instability： determination of the center of the glenoid inferior portion

目的 探讨在正常肩盂CT三维重建标准正面观影像上确定肩盂下部圆心的可行性,比较同一个体左、右肩盂的半径大小,为术前精确定量评估肩盂骨缺损比例提供影像学依据. 方法 本研究测量了35例成人双侧正常肩盂（共70个）,每个肩盂均行64层螺旋CT扫描,由1位医生在三维工作站上获得肩盂的标准三维正面观影像及标尺,并将其以二维图像的格式导出.3位医生分别利用AutoCAD2006软件对图像进行处理,做肩盂下部前缘最突点、下缘最突点连线的垂直平分线,再做后缘最突点、下缘最突点连线的垂直平分线,将两垂直平分线的交点定为肩盂下部的圆心,分别测量该点到肩盂前下缘、后下缘和后缘的距离.比较3位医生测量的圆心到肩盂前下缘、后下缘和后缘距离值,以及左、右肩盂相应距离的测量数据. 结果 肩盂下部圆心到肩盂后缘最突点之间的距离（即圆的半径）为（14.1±1.6）mm,到肩盂前下缘的距离为（14.0±1.7）mm,到肩盂后下缘的距离为（14.1±1. 6）mm.3位医生测量的圆心到肩盂后缘距离值之间及左、右肩盂相应测量值之间差异均无统计学意义（P〉0.05）. 结论 在正常肩盂的CT三维标准正面观影像上利用肩盂下部前、后、下缘最突点确定肩盂下部圆心的方法是简便、可行的,可重复性较高.正常人左右肩盂下部的半径是一致的.以上结论可用于单侧肩盂骨缺损的精确定量评价.

Objective To explore the feasibility and application of determining the center of the inferior portion of the glenoid on a standard anteroposterior view of the normal glenoid. Methods Seventy shoulders of 35 mature adults were measured in this study. A 64-slice CT 3D reconstruction was performed for each glenoid. A standard anteroposterior view and the scale of glenoid were made at a 3D workstation by one radiologist, and then transferred to software AutoCAD as 2D images. The 2D images were analyzed with AutoCAD respectively by 3 radiologists. The line was drawn between the most anterior and the most inferior points of the glenoid bony rim. On the same image, another line was drawn between the most posterior and the most inferior points of the glenoid bony rim. Two perpendicular bisectors of the 2 lines were drawn. The cross point of the 2 perpendicular bisectors was regarded as the circle center of the inferior part of the glenoid. The distances from the circle center to the anteroinferior and the posteroinferoir rims of the glenoid and the most posterior point were measured. Measurements were expressed as the mean ± standard deviation. Several related samples Friedman rank sum test was used to compare the measurements （the distance from the circle center to the most posterior point） by the 3 radiologists. Paired t tests were used to compare the differences between the left and right glenoids. Results The mean distance from the circle center to the most posterior point was （ 14. 1 ± 1.6） mm, the anteroinferior rim was （ 14. 0 ± 1.7） mm, and the posteroinferoir rim was （ 14. 1 ±1.6） mm. No significant differences were found （ P〉0. 05） between measurements by the 3 radiologists. No significant differences were found （ P〉0. 05） between the measurements of the both-side glenoids. Conclusions The method of determining the center of the inferior portion of the glenoid based on the most anterior,posterior and inferior points of the glenoid on a standard 3D anteroinferior view of the normal glenoid is easy,practical and highly repeatable. The radius of the left glenoid is comparable to the radius of the right side in normal shoulders. This method can be used to quantify a glenoid bone defect precisely.