Mechanistic Characterization of Shoulder Function and Tissue Loading

肩部功能对人体活动至关重要。在现代世界中，肩部组织承受的负荷和情景往往会导致损伤、生活质量下降和生产力下降。超过一半的加拿大人在他们的一生中会有肩部损伤。拟议研究计划的指导目标是系统地提高肩部组织机械暴露、失败容限及其相互作用的量化，以更好地了解健康的肩部功能及其对人类生活的影响。*肩部和人类是复杂的共生机械系统。肩部令人难以置信的灵活性允许不同的功能，但代价是机械关节稳定性较低。整个人类群体的生物变异性使肩部评估进一步复杂化。我提出的研究将通过三个相互关联的目标解决肩部力学中的关键基本不确定性。*目标1：描述多尺度总体变异性对硅胶中组织暴露的影响：在我现有的肩部模型中，五个主要指标将被视为变量参数，以定义哪个指标(S)对组织反应影响最大。这些因素包括：1)组织组成，2)肩关节稳定性，3)肩部节律，4)节段性运动学，5)任务要求。目标2：量化肩部肌肉疲劳对体内运动学反应的影响：肩部必须在多种应激源存在的情况下发挥作用。肌肉疲劳是改变正常肩部力学的主要因素之一。我们将使用多维象征性运动片段表征来识别实验性疲劳进程。这些数据将被用来改进概率模型(Obj.1)和指导组织耐受性测试方案(Obj.目标3：确定组织对体外真实机械负荷的耐受性：生理的冈上肌腱负荷与肩部令人难以置信的姿势灵活性是分不开的，这会导致未经测试的复杂肌腱变形。标本将用一种新型的局部组织系统进行测试，该系统能够应用复杂的载荷分布，产生关于扭转、局部和纵向联合暴露的影响的高级数据，以帮助阐明冈上肌腱失效机制(OBJ)。1)。*总而言之，肩部力学-从骨骼运动到特定的组织负荷和失效模式-将通过生物力学领域的综合、尖端方法进行评估。数据驱动的概率模型将超过目前描述人类肩部力学的尝试，提供反映人类变异性的肩部行为描述。最终，这些对肩部功能的基本见解将为保持和开发我们上肢无与伦比的潜力的方法提供指导。

Shoulder function is crucial for human activities. In the modern world, shoulder tissues experience loads and scenarios that often cause damage, decreases in quality of life, and reduced productivity. Over half of Canadians will have shoulder damage in their lifetimes. The guiding objective of the proposed research program is to systematically improve quantification of shoulder tissue mechanical exposures, failure tolerances, and their interactions to better understand healthy shoulder function and its implications for human life.***Shoulders and humans are complex, symbiotic mechanical systems. The incredible flexibility of the shoulder allows diverse capabilities, but comes at the cost of low mechanical joint stability. Biological variability across the human population further complicates shoulder evaluation. My proposed research will resolve crucial fundamental uncertainties in shoulder mechanics through three linked objectives.******Objective 1: Characterize the influence of multi-scale population variability on tissue exposures in silico: Five major metrics will be treated as variable parameters within my existing shoulder model to define which metric(s) influence tissue response the most. These are: 1) tissue composition, 2) glenohumeral stability, 3) shoulder rhythm, 4) segmental kinematics, and 5) task demands.******Objective 2: Quantify the effects of shoulder muscle fatigue on kinematic responses in vivo: The shoulder must function in the presence of many stressors. Muscular fatigue is one of the primary factors that alters normal shoulder mechanics. We will use multi-dimensional symbolic motion segment characterization to identify experimental fatigue progression. The data will be used to improve the dynamic fatigue response of the probabilistic model (Obj. 1) and to guide tissue tolerance testing protocols (Obj. 3).******Objective 3: Define tissue tolerances to realistic mechanical loads in vitro: Physiological supraspinatus tendon loading is inseparable from the shoulder's incredible postural flexibility, which causes untested complex tendon deformation. Specimens will be tested with a novel focal tissue system capable of applying complex load profiles, yielding advanced data on the influences of combined torsional, focal, and longitudinal exposures to help clarify supraspinatus tendon failure mechanisms (Obj. 1). ***In summary, shoulder mechanics from bone movement to specific tissue loads and failure modes - will be assessed with integrative, cutting edge approaches from across the field of biomechanics. The data-driven probabilistic model will exceed current attempts to describe human shoulder mechanics, providing descriptions of shoulder behavior that reflect human variability. Ultimately, these fundamental insights into shoulder function will provide guidance on methods to maintain and exploit the incomparable potential of our upper limbs.**