Rotator cuff tendon tears and tendinopathies are common injuries affecting a large portion of the population and can result in pain and joint dysfunction. Incidence of rotator cuff tears significantly increases with advancing age, and up to 90% of these tears involve the supraspinatus. Previous literature has shown that aging can lead to inferior mechanics, altered composition, and changes in structural properties of the supraspinatus. However, there is little known about changes in supraspinatus mechanical properties in context of other rotator cuff tendons. Alterations in tendon mechanical properties may indicate damage and an increased risk of rupture, and thus, the purpose of this study was to use a rat model to define age-related alterations in rotator cuff tendon mechanics to determine why the supraspinatus is more susceptible to tears due to aging than the infraspinatus, subscapularis, and teres minor. Fatigue, viscoelastic, and quasi-static properties were evaluated in juvenile, adult, aged, and geriatric rats. Aging ubiquitously and adversely affected all rotator cuff tendons tested, particularly leading to increased stiffness, decreased stress relaxation, and decreased fatigue secant and tangent moduli in geriatric animals, suggesting a common intrinsic mechanism due to aging in all rotator cuff tendons. This study demonstrates that aging has a significant effect on rotator cuff tendon mechanical properties, though the supraspinatus was not preferentially affected. Thus, we are unable to attribute the aging-associated increase in supraspinatus tears to its mechanical response alone.

肩袖肌腱撕裂和肌腱病是影响大部分人群的常见损伤，可导致疼痛和关节功能障碍。随着年龄的增长，肩袖撕裂的发生率显着增加，其中高达 90% 的撕裂涉及冈上肌。以前的文献表明，老化会导致冈上肌力学性能下降、成分改变和结构特性发生变化。然而，在其他肩袖肌腱的情况下，冈上肌力学性能的变化知之甚少。肌腱力学性能的改变可能表明损伤和断裂风险增加，因此，这项研究的目的是使用大鼠模型来定义与年龄相关的肩袖肌腱力学变化，以确定为什么冈上肌比冈下肌、肩胛下肌和小圆肌更容易因衰老而流泪。在幼年、成年、老年和老年大鼠中评估疲劳、粘弹性和准静态特性。老化对所有测试的肩袖肌腱普遍存在不利影响，特别是导致老年动物的刚度增加、应力松弛降低以及疲劳正割和切线模量降低，这表明所有肩袖肌腱老化的共同内在机制。这项研究表明，老化对肩袖肌腱的机械性能有显着影响，尽管冈上肌并未受到优先影响。因此，