Background 

Bony Bankart lesions larger than a certain size can lead to a high redislocation rate, despite treatment with Bankart repair. Detection and measurement of glenoid bone loss play key roles in selecting the appropriate surgical therapy in patients with shoulder instability. There is controversy about which diagnostic modalities, using different measurement methods, provide the best diagnostic validity.

Questions/purposes 

(1) What are the diagnostic accuracies of true AP radiographs, West Point (WP) view radiographs, MRI, and CT to detect glenoid bone loss? (2) Are there differences in the measurements of glenoid bone loss on MRI and CT? (3) What are the intrarater and interrater reliabilities of CT and MRI to measure glenoid bone loss?

Methods 

Between August 2012 and February 2017, we treated 80 patients for anterior shoulder instability. Of those, we considered patients with available preoperative true AP radiographs, WP radiographs, CT images, and MR images of the affected shoulder as potentially eligible. Based on that, 63% (50 of 80) of patients were eligible for analysis; 31% (25 of 80) were excluded because not all planes or slices (such as sagittal, axial, or frontal) of each diagnostic imaging modalities were available and 7% (5 of 80) because of the insufficient quality of diagnostic images (for example, setting of the layers did not allow adequate en face view of the glenoid). Preoperative true AP radiographs, WP radiographs, CT images and MR images of the affected shoulders were retrospectively assessed for the presence of glenoid bone loss by two blinded observers at a median (range) 25 months (12 to 66) postoperatively. To evaluate sensitivity, specificity, positive predictive value, negative predictive value, accuracy, diagnostic odds ratio, positive likelihood ratio, negative likelihood ratio, and area under the curve (AUC), we compared the detection of glenoid bone loss at follow-up achieved with the aforementioned imaging modalities with intraoperative arthroscopic detection. In all patients with glenoid bone loss, two blinded observers measured the size of the glenoid bone loss on preoperative CT and MR images using six measuring techniques: depth and length of the glenoid bone loss, Bigliani classification, best-fit circle width loss method, AP distance method, surface area method, and Gerber X ratio. Subsequently, the sizes of the glenoid bone loss determined using CT and MRI were compared. To estimate intraobserver and interobserver reliability, measurements were performed in a blinded fashion by two observers. Their level of experience was equivalent to that of orthopaedic residents, and they completed a training protocol before the measurements.

Results 

For the ability to accurately diagnose Bankart lesions, the AUC (accuracy of a diagnostic test; the closer to 1.0, the more accurate the test) was good for MRI (0.83 [95% confidence interval 0.70 to 0.94]; p < 0.01), fair for CT (0.79 [95% CI 0.66 to 0.92]; p < 0.01), poor for WP radiographs (0.69 [95% CI 0.54 to 0.85]; p = 0.02) and failed for true AP radiographs (0.55 [95% CI 0.39 to 0.72]; p = 0.69). In paired comparisons, there were no differences between CT and MRI regarding (median [range]) lesion width (2.33 mm [0.35 to 4.53] versus 2.26 mm [0.90 to 3.47], p = 0.71) and depth (0.42 mm [0.80 to 1.39] versus 0.40 mm [0.06 to 1.17]; p = 0.54), and there were no differences concerning the other measurement methods: best-fit circle width loss method (15.02% [2.48% to 41.59%] versus 13.38% [2.00% to 36.34%]; p = 0.66), AP distances method (15.48% [1.44% to 42.01%] versus 12.88% [1.43% to 36.34%]; p = 0.63), surface area method (14.01% [0.87% to 38.25] versus 11.72% [2.45% to 37.97%]; p = 0.68), and Gerber X ratio (0.75 [0.13 to 1.47] versus 0.76 [0.27 to 1.13]; p = 0.41). Except for the moderate interrater reliability of the Bigliani classification using CT (intraclass correlation coefficient = 0.599 [95% CI 0.246 to 0.834]; p = 0.03) and acceptable interrater reliability of the Gerber X ratio using CT (0.775 [95% CI 0.542 to 0.899]; p < 0.01), all other measurement methods had good or excellent intrarater and interrater reliabilities on MRI and CT.

Conclusion 

The results of this study show that CT and MRI can accurately detect glenoid bone loss, whereas WP radiographs can only recognize them poorly, and true AP radiographs do not provide any adequate diagnostic accuracy. In addition, when measuring glenoid bone loss, MRI images of the analyzed measurement methods yielded sizes that were no different from CT measurements. Finally, the use of MRI images to measure Bankart bone lesions gave good-to-excellent reliability in the present study, which was not inferior to CT findings. Considering the advantages including lower radiation exposure and the ability to assess the condition of the labrum using MRI, we believe MRI can help surgeons avoid ordering additional CT imaging in clinical practice for the diagnosis of anterior shoulder instability in patients with glenoid bone loss. Future studies should investigate the reproducibility of our results with a larger number of patients, using other measurement methods that include examination of the opposite side or with three-dimensional reconstructions.

Level of Evidence 

Level I diagnostic study.

中文翻译：

---

MRI 可准确测量关节盂骨质流失

背景 

尽管采用 Bankart 修复治疗，但大于一定尺寸的骨性 Bankart 病变仍可能导致较高的再脱位率。关节盂骨丢失的检测和测量对于肩关节不稳患者选择适当的手术治疗起着关键作用。关于使用不同测量方法的哪种诊断方式可提供最佳的诊断有效性存在争议。

问题/目的 

(1) 真正的 AP 射线照片、西点 (WP) 视图射线照片、MRI 和 CT 检测关节盂骨丢失的诊断准确性是多少？（2）MRI和CT测量的关节盂骨丢失是否有差异？(3) CT 和 MRI 测量关节盂骨丢失的评估者内和评估者间可靠性是多少？

方法 

2012年8月至2017年2月期间，我们治疗了80名肩前不稳定患者。其中，我们认为具有术前真实的受累肩部 X 线照片、WP X 线照片、CT 图像和 MR 图像的患者可能符合资格。基于此，63%（80 名患者中的 50 名）符合分析条件；31%（80 人中的 25 人）被排除，因为并非每种诊断成像方式的所有平面或切片（例如矢状面、轴向或额叶）都可用，7%（80 人中的 5 人）因为诊断图像质量不够（对于例如，层的设置不允许关节盂有足够的正面视图）。由两名盲人观察者在术后中位（范围）25 个月（12 至 66 个月）时回顾性评估受累肩部的术前真实 AP 射线照片、WP 射线照片、CT 图像和 MR 图像是否存在关节盂骨丢失。为了评估敏感性、特异性、阳性预测值、阴性预测值、准确性、诊断比值比、阳性似然比、阴性似然比和曲线下面积 (AUC)，我们比较了随访时关节盂骨丢失的检测结果使用上述成像方式与术中关节镜检测。在所有患有关节盂骨丢失的患者中，两名盲人观察者使用六种测量技术在术前 CT 和 MR 图像上测量了关节盂骨丢失的大小：关节盂骨丢失的深度和长度、Bigliani 分类、最佳拟合圆宽度丢失方法、 AP距离法、表面积法、Gerber X比。随后，比较使用 CT 和 MRI 确定的关节盂骨丢失的大小。为了估计观察者内和观察者间的可靠性，由两名观察者以盲法进行测量。他们的经验水平与骨科住院医师相当，并且在测量前完成了培训方案。

结果 

对于准确诊断 Bankart 病变的能力，MRI 的 AUC（诊断测试的准确性；越接近 1.0，测试越准确）非常好（0.83 [95% 置信区间 0.70 至 0.94]；p < 0.01）， CT 尚可（0.79 [95% CI 0.66 至 0.92]；p < 0.01），WP X 线照片较差（0.69 [95% CI 0.54 至 0.85]；p = 0.02），真实 AP X 线照片失败（0.55 [95% CI]） 0.39 至 0.72]；p = 0.69）。在配对比较中，CT 和 MRI 在（中位[范围]）病变宽度（2.33 mm [0.35 至 4.53] 与 2.26 mm [0.90 至 3.47]，p = 0.71）和深度（0.42 mm [0.80 至 3.47]）和深度（0.42 mm [0.80 至 3.47]）方面没有差异。 1.39] 与 0.40 mm [0.06 至 1.17]；p = 0.54），并且其他测量方法没有差异：最佳拟合圆宽度损失方法（15.02% [2.48% 至 41.59%] 与 13.38% [2.00%]至 36.34%]；p = 0.66），AP 距离法（15.48% [1.44% 至 42.01%] 与 12.88% [1.43% 至 36.34%]；p = 0.63），表面积法（14.01% [0.87% 至 38.25]） ] 与 11.72% [2.45% 至 37.97%]；p = 0.68），以及 Gerber X 比率（0.75 [0.13 至 1.47] 与 0.76 [0.27 至 1.13]；p = 0.41）。除了使用 CT 的 Bigliani 分类具有中等的受试者间可靠性（组内相关系数 = 0.599 [95% CI 0.246 至 0.834]；p = 0.03）以及使用 CT 的 Gerber X 比率的可接受的受试者间可靠性（0.775 [95% CI 0.542 至0.899]；p < 0.01），所有其他测量方法在 MRI 和 CT 上均具有良好或优异的评估者内和评估者间可靠性。

结论 

这项研究的结果表明，CT 和 MRI 可以准确地检测关节盂骨质流失，而 WP X 线照片只能很差地识别它们，而真正的 AP X 线照片不能提供任何足够的诊断准确性。此外，在测量关节盂骨丢失时，所分析的测量方法的 MRI 图像产生的尺寸与 CT 测量结果没有什么不同。最后，在本研究中使用 MRI 图像测量 Bankart 骨病变给出了良好到极好的可靠性，这并不逊色于 CT 结果。考虑到 MRI 的辐射暴露较低以及能够评估盂唇状况等优点，我们相信 MRI 可以帮助外科医生在临床实践中避免额外进行 CT 成像来诊断肩关节盂骨丢失患者的肩关节前不稳定。未来的研究应该使用其他测量方法（包括检查对侧或三维重建）来调查我们的结果在更多患者中的重现性。

证据水平 

I 级诊断研究。