CORR：关节盂骨缺损面积采用3D-CT评估最为准确

创伤后的肩关节前侧不稳定往往和肩胛盂关节面前方的骨缺损相关，目前推荐对骨缺损范围大于20-27%的患者进行骨重建以避免肩关节手术后脱位再复发，因此在进行肩关节手术治疗前精确的评估前方骨缺损的范围对手术方案的制定非常重要。目前已有无创性评估肩胛骨关节盂缺损的方法有X片，普通CT，磁共振，及三维CT，上诉方法在临床中应用较多，但目前尚无研究对上诉方法的准确性进行评估，近期来自美国的学者就上述问题进行尸体标本的研究，发现术前的三维CT可以较为精确的评估肩胛盂部位骨缺损，相关结论发表在近期出版的CORR杂志上。

研究共采集7具肩关节尸体标本，4左3右，在对标本进行处理前先是用四种方法（X片，普通CT，磁共振，及三维CT）记录标本的原始数据；对7具尸体标本进行如下处置：人为制造肩胛盂前方骨缺损，面积分别为<12%，12-25%，25-40%，每次完成缺损标本的制作后，使用游标卡尺进行直视下标本缺损范围的测量，该测量值作为实际缺损范围的金标准，并通过四种影像学方法记录标本的图像数据，与直视下测量的标本实际缺损范围进行比较，共获取112幅影像学资料（7具标本×4种方法×4种缺损范围，图1），12个独立观察者对112副影像学资料进行观察，确定骨缺损的范围，并和实际缺损值进行比较，确定四种测量方法的组间一致性（interobserver reliability）；2月后相同的12位观察者对同样的图像进行观察，确定组内一致性（intraobserver reliability），可靠一致性统计指标采用kappa值。

 
图1：随机呈现的一具标本的四种影像学图片，A图X片，B图MRI，C图普通CT，D图三维CT扫描

研究结果提示：

不同观察者评估标本缺损范围和实际缺损范围一致性最高者为三维CT，0.50；最低者为X片，0.15，如图2；

 
图2：影像学评估标本缺损和实际标本缺损的总体一致性；

不考虑缺损范围，组间一致性由高至低分别为3-D CT, 0.54; CT, 0.47; MRI, 0.31;and radiographs, 0.15，如图3；

 
图3：不考虑骨缺损范围，不同影像学标本组间一致性比较；

不考虑影像类型，评估缺损一致率最高的是无缺损组和缺损>25%组，而缺损一致率最差的是0-25%组，如图4；

 
图4：不考虑影像学类型，不同缺损范围的一致性比较；

按缺损率大小进行影像学精准性评估，在0%缺损精确性最高的为三维CT（0.82）；0-12%，三维CT（0.52）；12-25%，三维CT（0.38）；25-40%，三维CT（0.57），如图5；

 
图5：按缺损率大小进行影像学精准性评估；

组内一致性由高至低分别为：CT, 0.64; 3-D CT, 0.59; MRI, 0.51; radiographs, 0.45，如图6；

 
图6：不论缺损范围大小，组内一致性比较；

研究者总结：术前三维CT 在各种测量方法中具有较好的准确率，组间一致性及组内一致性，可以相对精确的评估骨缺损，推荐广大骨科医生使用该方法进行影像学评估。但作者在讨论中也同时指出：即使三维CT较其他影像学方法更精确，其在评估0-25%缺损组时的精确性也仍存在不足，因此不能过分依赖术前三维CT结果；对部分不存在三维重建的医疗机构，使用CT作为替代评估也是一种可行的方法。

3-D CT is the most reliable imaging modality when quantifying glenoid bone loss.
BACKGROUND
Posttraumatic anterior shoulder instability is associated with anterior glenoid bone loss, contributing to recurrence. Accurate preoperative quantification of bone loss is paramount to avoid failure of a soft tissue stabilization procedure as bone reconstruction is recommended for glenoid defects greater than 20% to 27%.
QUESTIONS/PURPOSES
We determined whether radiography, MRI, or CT was most reliable to quantify glenoid bone loss in recurrent anterior shoulder instability.
METHODS
Seven intact fresh-frozen human cadaveric shoulders were imaged with radiography, MRI, CT, and three-dimensional (3-D) CT. Three sequential anterior glenoid defects then were created, measured, and the shoulders reimaged after each defect. Defect sizes were less than 12%, 12% to 25%, and 25% to 40%. The gold standard measurement was determined by comparing measurements taken on the cadaver by two surgeons using digital calipers with the measurements determined by using electronic digital calipers on the 3-D CT. This measurement was used for comparison of all estimations by the evaluators. Twelve independent blinded evaluators reviewed the 112 image sets and estimated the percent of glenoid bone loss. Images were scrambled and rereviewed by the same observers 2 months later to determine intraobserver reliability. We determined reliability with kappa values.
RESULTS
Kappa values between predicted bone loss versus true loss (determined by our gold standard measurements) across all 12 raters for each modality were: 3-D CT, 0.50; CT, 0.40; MRI, 0.27; and radiographs, 0.15. Interobserver agreement (kappa) values were: 3-D CT, 0.54; CT, 0.47; MRI, 0.31; and radiographs, 0.15. The intraobserver agreement (kappa) values were: 3-D CT, 0.59; CT, 0.64; MRI, 0.51; and radiographs, 0.45.
CONCLUSIONS
Three-dimensional CT was the most reliable imaging modality for predicting glenoid bone loss. Regular CT was the second most reliable and reproducible modality.