Alex Vaisman, Facultad de Medicina Clínica Alemana Universidad del Desarrollo, Francisco Bulnes Correa 3737, dep B-31, Las Condes, Santiago, Chile.
Am J Sports Med. 2014 Jan;42(1):112-6. doi: 10.1177/0363546513506849. Epub 2013 Oct 11.
Posterior acromioclavicular (AC) joint dislocations are frequently misclassified because posterior translation of the clavicle is difficult to evaluate in Zanca radiograph views. A novel radiographic index was used in this study to accurately diagnose posterior dislocations of the AC joint.
This novel index has a high degree of accuracy for the diagnosis of posterior AC joint dislocations.
Cohort study (diagnosis); Level of evidence, 2.
This was an analytic, descriptive study of 150 patients with different grades of AC injuries according to the Rockwood classification (30 patients for each grade of injury: I, II, III, IV, and V). The diagnosis of an AC injury was made both clinically and radiographically by using comparative Zanca and axillary views. Two measurements were performed in Zanca views: the coracoclavicular distance and the AC width distance. A width index was calculated for each patient. The Student t test, Bonferroni test, logistic regression, linear regression, and receiver operating characteristic (ROC) curves were used for statistical analysis. Forty cases were impartially selected to obtain a κ concordance value.
The average value of the AC width index per group (according to the Rockwood classification) was as follows: type I, 2.1% (range, -12% to 25%); type II, 4.2% (range, -19% to 29%); type III, 19.1% (range, -59% to 91%); type IV, 110.3% (range, 47% to 181%); and type V, -3.8% (range, -71% to 62%). There was a significant difference between the average width index in the patients with type IV injuries and those in the remaining groups (P < .05). The ROC curve showed that a width index of 60% has a sensitivity of 95.7% and specificity of 97.5%, with a positive predictive value of 96.7% and negative predictive value of 95.6% to predict a type IV injury. Intraobserver reliability was rated as substantial agreement for each of 3 observers; the interobserver reliability of the 3 independent raters was almost perfect.
An AC width index of ≥60% is highly accurate for the diagnosis of a posterior AC joint dislocation, with high intraobserver and interobserver concordance.
由于难以评估锁骨后向移位，因此经常错误分类后肩锁关节（AC）脱位。本研究使用一种新的影像学指数来准确诊断 AC 关节后脱位。
这种新的指数对于诊断 AC 关节后脱位具有很高的准确性。
队列研究（诊断）；证据水平，2 级。
这是一项对 150 名根据 Rockwood 分类具有不同 AC 损伤程度的患者（每组 30 例：I、II、III、IV 和 V 级损伤）的分析性描述性研究。通过比较 Zanca 和腋侧位片进行临床和影像学诊断 AC 损伤。在 Zanca 位片上进行了两项测量：喙锁间距和 AC 宽度距离。为每位患者计算了一个宽度指数。使用学生 t 检验、Bonferroni 检验、逻辑回归、线性回归和受试者工作特征（ROC）曲线进行统计学分析。随机选择 40 例以获得 κ 一致性值。
每组（根据 Rockwood 分类）AC 宽度指数的平均值如下：I 型，2.1%（范围，-12%至 25%）；II 型，4.2%（范围，-19%至 29%）；III 型，19.1%（范围，-59%至 91%）；IV 型，110.3%（范围，47%至 181%）；V 型，-3.8%（范围，-71%至 62%）。IV 型损伤患者的平均宽度指数与其余各组之间存在显著差异（P <.05）。ROC 曲线显示，宽度指数为 60%时，对预测 IV 型损伤的敏感性为 95.7%，特异性为 97.5%，阳性预测值为 96.7%，阴性预测值为 95.6%。3 名观察者的每项观察者内可靠性均评为高度一致；3 名独立评分者的观察者间可靠性几乎为完美。
AC 宽度指数≥60%高度准确地诊断 AC 关节后脱位，观察者内和观察者间一致性高。
