Saengpetch Nadhaporn, Bamrungchaowkasem Jaturong, Chitrapazt Niyata, Kongmalai Pinkawas
Department of Orthopaedics, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand.
Department of Radiology, Faculty of Medicine, Mahidol University, Bangkok, Thailand.
Asia Pac J Sports Med Arthrosc Rehabil Technol. 2024 Nov 27;39:15-21. doi: 10.1016/j.asmart.2024.11.003. eCollection 2025 Jan.
Bursal-side supraspinatus tendon tears are a common form of rotator cuff injury, often associated with acromial impingement and other extrinsic factors. Existing anatomical parameters, such as the lateral acromion angle, acromial index, and critical shoulder angle, have been studied in relation to rotator cuff tears; however, reliable indicators specific to the risk of bursal-side supraspinatus tears remain lacking. The acromioclavicular (AC) angle, which reflects the angular relationship between the acromion and clavicle, may offer a new predictive marker for this specific pathology.
In this retrospective case-control study, patients presenting with shoulder pain between January 2016 and February 2020 were reviewed. Group 1 included patients with isolated bursal-side supraspinatus tendon tears confirmed by arthroscopy, while Group 2 consisted of age- and gender-matched controls without rotator cuff pathology. The AC angle was measured using both X-ray and MRI. Diagnostic performance was assessed through Receiver Operating Characteristic (ROC) curve analysis, identifying the optimal cut-point with Youden's index. Reliability was measured using the Intraclass Correlation Coefficient (ICC) for both intra- and inter-rater reliability.
The ROC analysis determined an optimal AC angle cut-point of ≤160°. X-ray measurements showed moderate diagnostic value (AUC 0.60, sensitivity 67.2 %, specificity 51.7 %), while MRI measurements demonstrated good diagnostic performance (AUC 0.79, sensitivity 84.5 %, specificity 70.7 %). X-ray yielded high sensitivity but low specificity, suggesting its utility as an initial screening tool, whereas MRI provided improved diagnostic accuracy. Reliability assessments indicated high intra- and inter-rater reliability for AC angle measurements across both imaging modalities (ICC >0.80).
The AC angle, particularly when measured on MRI, may serve as a valuable diagnostic marker for identifying isolated bursal-side supraspinatus tendon tears. While X-ray can be utilized as an accessible screening tool, combining it with clinical assessments and MRI is recommended for greater diagnostic precision. Further multi-center, prospective studies are warranted to confirm the clinical utility of the AC angle in predicting rotator cuff pathology.
滑囊侧冈上肌腱撕裂是肩袖损伤的常见形式，常与肩峰撞击及其他外在因素相关。现有的解剖学参数，如外侧肩峰角、肩峰指数和临界肩角，已针对肩袖撕裂进行了研究；然而，仍缺乏针对滑囊侧冈上肌腱撕裂风险的可靠指标。肩锁（AC）角反映了肩峰与锁骨之间的角度关系，可能为这种特定病理情况提供一种新的预测标志物。
在这项回顾性病例对照研究中，对2016年1月至2020年2月期间出现肩部疼痛的患者进行了评估。第1组包括经关节镜证实为孤立性滑囊侧冈上肌腱撕裂的患者，而第2组由年龄和性别匹配、无肩袖病变的对照组组成。使用X线和磁共振成像（MRI）测量AC角。通过受试者操作特征（ROC）曲线分析评估诊断性能，用约登指数确定最佳切点。使用组内相关系数（ICC）测量评分者内和评分者间的可靠性。
ROC分析确定AC角的最佳切点为≤160°。X线测量显示出中等诊断价值（曲线下面积[AUC]为0.60，敏感性为67.2%，特异性为51.7%），而MRI测量显示出良好的诊断性能（AUC为0.79，敏感性为84.5%，特异性为70.7%）。X线敏感性高但特异性低，表明其可作为初始筛查工具，而MRI提供了更高的诊断准确性。可靠性评估表明，两种成像方式下AC角测量的评分者内和评分者间可靠性均较高（ICC>0.80）。
AC角尤其是通过MRI测量时，可能是识别孤立性滑囊侧冈上肌腱撕裂的有价值的诊断标志物。虽然X线可作为一种便捷的筛查工具，但建议将其与临床评估和MRI相结合以提高诊断精度。有必要开展进一步的多中心前瞻性研究，以证实AC角在预测肩袖病变方面的临床实用性。
