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Abstract：
The deltoid muscle and rotator cuff tissue are structural components that maintain the dynamic stability of the shoulder joint. However, atrophy of the deltoid muscle may affect the stability of the shoulder joint, which in turn alters the mechanical distribution of rotator cuff tissue. Currently, the effect of muscle volume changes in the deltoid muscle on reducing the load on the rotator cuff tissue is still unknown. Therefore, this paper intends to analyze the mechanical changes of rotator cuff tissue by deltoid muscle atrophy through finite elements. Based on previously published finite element shoulder models, the deltoid muscle was modeled by constructing deltoid muscle models with different degrees of atrophy as, 100% deltoid muscle (Group 1), 80% deltoid muscle (Group 2), and 50% deltoid muscle (Group 3), respectively. The three models were given the same external load to simulate glenohumeral joint abduction, and the stress changes in the rotator cuff tissue were analyzed and recorded. In all three models, the stress in the rotator cuff tissue showed different degrees of increase with the increase of abduction angle, especially in the supraspinatus muscle. At 90° of glenohumeral abduction, supraspinatus stress increased by 58% and 118% in Group 2 and Group 3, respectively, compared with Group 1; In the subscapularis, the stress in Group 3 increased by 59% and 25% compared with Group 1 and Group 2, respectively. In addition, the stress of the infraspinatus muscle and teres minor muscle in Group 2 and Group 3 were higher than that in Group 1 during the abduction angle from 30° to 90°. Deltoid atrophy alters the abduction movement pattern of the glenohumeral joint. During glenohumeral abduction activity, deltoid atrophy significantly increases the stress on the rotator cuff tissue, whereas normal deltoid volume helps maintain the mechanical balance of the rotator cuff tissue.
摘要：
三角肌和肩袖组织是维持肩关节动态稳定性的结构部件。然而,三角肌萎缩可能会影响肩关节的稳定性，这又改变了肩袖组织的机械分布。目前,三角肌的肌肉体积变化对减轻肩袖组织负荷的作用尚不清楚。因此,本文拟通过有限元分析三角肌萎缩对肩袖组织的力学变化。基于先前发布的有限元路肩模型，通过构建不同程度萎缩的三角肌模型对三角肌进行建模，100%三角肌(第1组),80%三角肌(第2组),和50％的三角肌（第3组），分别。三种模型均给予相同的外载荷来模拟肱骨关节外展,分析并记录肩袖组织的应力变化。在所有三个模型中，随着外展角的增大,肩袖组织内的应力呈不同程度的增大,尤其是在冈上肌.肱骨外展90°,在第2组和第3组中，冈上肌应激分别增加了58%和118%，与第1组相比；在肩胛骨下，与第1组和第2组相比,第3组的应激分别增加了59%和25%.此外,在外展角30°至90°期间，第2组和第3组的冈下肌和小圆肌的应力高于第1组。三角肌萎缩改变了肱骨关节的外展运动模式。在肱骨外展活动期间,三角肌萎缩显著增加肩袖组织的应力，而正常的三角肌体积有助于维持肩袖组织的机械平衡。
