Williamson Patrick M, Hanna Philip, Momenzadeh Kaveh, Lechtig Aron, Okajima Stephen, Ramappa Arun J, DeAngelis Joseph P, Nazarian Ara
Boston University, Mechanical Engineering Department, Boston, MA, USA; Center for Advanced Orthopaedic Studies at Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA.
Center for Advanced Orthopaedic Studies at Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA.
J Biomech. 2020 May 22;105:109798. doi: 10.1016/j.jbiomech.2020.109798. Epub 2020 Apr 18.
Healthy shoulder function requires the coordination of the rotator cuff muscles to maintain the humeral head's position in the glenoid. While glenohumeral stability has been studied in various settings, few studies have characterized the effect of dynamic rotator cuff muscle loading on glenohumeral translation during shoulder motion. We hypothesize that dynamic rotator cuff muscle activation decreases joint translation during continuous passive abduction of the humerus in a cadaveric model of scapular plane glenohumeral abduction. The effect of different rotator cuff muscle activity on glenohumeral translation was assessed using a validated shoulder testing system. The Dynamic Load profile is a novel approach, based on musculoskeletal modeling of human subject motion. Passive humeral elevation in the scapular plane was applied via the testing system arm, while the rotator cuff muscles were activated according to the specified force profiles using stepper motors and a proportional control feedback loop. Glenohumeral translation was defined according to the International Society of Biomechanics. The Dynamic load profile minimized superior translation of the humeral head relative to the conventional loading profiles. The total magnitude of translation was not significantly different (0.805) among the loading profiles suggesting that the compressive forces from the rotator cuff primarily alter the direction of humeral head translation, not the magnitude. Rotator cuff muscle loading is an important element of cadaveric shoulder studies that must be considered to accurately simulate glenohumeral motion. A rotator cuff muscle activity profile based on human subject muscle activity reduces superior glenohumeral translation when compared to previous RC loading profiles.
健康的肩部功能需要肩袖肌群的协调作用来维持肱骨头在关节盂中的位置。虽然在各种情况下都对盂肱关节稳定性进行了研究，但很少有研究描述动态肩袖肌群负荷对肩部运动期间盂肱关节平移的影响。我们假设在肩胛平面盂肱关节外展的尸体模型中，动态肩袖肌群激活会减少肱骨持续被动外展期间的关节平移。使用经过验证的肩部测试系统评估不同肩袖肌群活动对盂肱关节平移的影响。动态负荷曲线是一种基于人体运动肌肉骨骼建模的新方法。通过测试系统臂在肩胛平面施加肱骨被动抬高，同时使用步进电机和比例控制反馈回路根据指定的力曲线激活肩袖肌群。盂肱关节平移根据国际生物力学学会的定义确定。相对于传统负荷曲线，动态负荷曲线使肱骨头的上移最小化。各负荷曲线之间的总平移幅度没有显著差异（0.805），这表明肩袖的压缩力主要改变肱骨头平移的方向，而不是幅度。肩袖肌群负荷是尸体肩部研究的一个重要因素，在准确模拟盂肱关节运动时必须予以考虑。与先前的肩袖负荷曲线相比，基于人体肌肉活动的肩袖肌群活动曲线可减少盂肱关节上移。
