Yeung Angus, Fernando Ashen, Patel Minoo, Gatto Laura, Ackland David C
Department of Biomedical Engineering, University of Melbourne, Parkville, Australia.
Department of Orthopaedic Surgery, Epworth Healthcare, Richmond, Australia.
J Orthop Res. 2024 Oct;42(10):2131-2139. doi: 10.1002/jor.25909. Epub 2024 Jun 12.
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.
全层肩袖撕裂可导致肱骨头与关节盂的对合不良，破坏盂肱关节稳定性所需的肌力，最终导致关节半脱位。本研究的目的是评估在存在孤立性和复合性全层肩袖撕裂的情况下，抬高过程中的肌力和盂肱关节移位情况。将8个新鲜冷冻上肢安装到计算机控制的测试装置上，通过模拟肌肉力施加来模拟关节运动。进行肩胛平面外展，并使用光电系统测量盂肱关节移位。测试在正常肩部、冈上肌孤立撕裂后、以及涉及冈上肌和肩胛下肌的复合撕裂、以及冈上肌、冈下肌和小圆肌的复合撕裂后进行。与正常肩部相比，肩袖撕裂在30°、60°和90°外展时显著增加了三角肌中部的力量（p < 0.05）。由于冈上肌和冈下肌在30°外展（平均增加：1.6 mm，p = 0.020）和60°外展（平均增加：4.8 mm，p = 0.040）时的复合撕裂，相对于完整肩部观察到明显更大的向上移位。本研究表明，冈下肌-小圆肌复合体是肱骨头的主要下压肌和盂肱关节稳定性的贡献者。在存在肩袖撕裂的情况下，外展时三角肌力量增加，这会加剧肱骨头的向上移位。这些发现可能有助于肩袖撕裂诊断中临床测试的开发、肩袖修复的手术规划以及有针对性康复的规划。
