Abstract：
Full-thickness rotator cuff tears can lead to poor coaptation of the humeral head to the glenoid, disrupting muscle forces required for glenohumeral joint stability, ultimately leading to joint subluxation. The aim of this study was to evaluate muscle forces and glenohumeral joint translations during elevation in the presence of isolated and combined full-thickness rotator cuff tears. Eight fresh-frozen upper limbs were mounted to a computer-controlled testing apparatus that simulated joint motion by simulated muscle force application. Scapular-plane abduction was performed, and glenohumeral joint translations were measured using an optoelectronic system. Testing was performed in the native shoulder, a following an isolated tear to the supraspinatus, as well as combined tears involving the supraspinatus and subscapularis, as well as supraspinatus, infraspinatus, and teres minor. Rotator cuff tears significantly increased middle deltoid force at 30°, 60°, and 90° of abduction relative to that in the native shoulder (p < 0.05). Significantly greater superior translations were observed relative to the intact shoulder due to combined tears to the supraspinatus and infraspinatus at 30° of abduction (mean increase: 1.6 mm, p = 0.020) and 60° of abduction (mean increase: 4.8 mm, p = 0.040). This study illustrates the infraspinatus-teres minor complex as a major humeral head depressor and contributor to glenohumeral joint stability. An increase in deltoid force during abduction occurs in the presence of rotator cuff tears, which exacerbates superior migration of the humeral head. The findings may help in the development of clinical tests in rotator cuff tear diagnostics, in surgical planning of rotator cuff repair, and in planning of targeted rehabilitation.
摘要：
全厚度肩袖撕裂会导致肱骨头与关节盂的接合不良，破坏肱骨关节稳定性所需的肌肉力量，最终导致关节半脱位。这项研究的目的是评估在孤立和合并的全厚度肩袖撕裂的情况下，抬高过程中的肌肉力量和肱骨关节平移。将八个新鲜冷冻的上肢安装到计算机控制的测试设备上，该设备通过模拟的肌肉力施加来模拟关节运动。进行肩胛骨平面外展,使用光电系统测量了盂肱关节的平移。测试是在本地肩部进行的，在冈上肌的孤立撕裂之后，以及涉及冈上肌和肩胛骨下的合并眼泪，以及冈上肌，冈底,和teresminor。肩袖撕裂在30°处显著增加中三角肌力，60°,和相对于天然肩部的外展90°（p<0.05）。由于在外展30°时对冈上肌和冈下肌的联合撕裂，相对于完整的肩部观察到明显更大的上翻译（平均增加：1.6毫米，p=0.020）和外展60°（平均增加：4.8mm，p=0.040)。这项研究说明了冈下小复合体是主要的肱骨头压迫剂，并有助于肱骨关节的稳定性。在存在肩袖撕裂的情况下，外展期间三角肌力增加，这加剧了肱骨头的上迁移。这些发现可能有助于开发肩袖撕裂诊断的临床测试，在肩袖修复的手术计划中，以及有针对性的康复计划。
