Abstract：
The supraspinatus tendon plays a crucial role in shoulder abduction, making it one of the common structures affected by injury. Clinically, crescent-shaped tears are the most commonly seen tear shape. By developing six specimen-specific, three-dimensional, supraspinatus-infraspinatus finite element model with heterogeneous material properties, this study aimed to examine the changes in tissue deformation (maximum principal strain) of the supraspinatus tendon due to specimen-specific material properties and rotator cuff tear size. FE models with small- and medium-sized full-thickness crescent-shaped tears were subjected to loads seen during activities of daily living and physiotherapy. Six fresh-frozen cadaveric shoulders were dissected to mechanically test the supraspinatus tendon and develop and validate FE models that can be used to assess changes in strain due to small (< 1 cm, equivalent to 20-30% of the tendon width) and medium-sized (1-3 cm, equivalent to 40-50% of the tendon width) tears that are located in the middle and posterior regions of the supraspinatus tendon. FE predictions of maximum principal strain at the tear tips were examined to determine whether failure strain was reached during activities of daily living (drinking and brushing teeth) and physiotherapy exercises (prone abduction and external rotation at 90° abduction). No significant differences were observed between the middle and posterior tear failure loads for small- and medium-sized tears. For prone abduction, there was a potential risk for tear progression (exceeded failure strain) for medium-sized tears in the supraspinatus tendon\'s middle and posterior regions. For external rotation at 90° abduction, one model with a middle tear and two with posterior tears experienced failure. For all daily activity loads, the strain never exceeded the failure strain. Our three-dimensional supraspinatus-infraspinatus FE model shows that small tears appear unlikely to progress based on the regional strain response; however, medium-sized tears are at higher risk during more strenuous physiotherapy exercises. Furthermore, differences in patient-specific tendon material properties are important in determining whether the tear will progress. Therefore, patient-specific management plans based on tear size may be beneficial to improve clinical outcomes.
摘要：
冈上肌腱在肩关节外展中起着至关重要的作用。使其成为受损伤影响的常见结构之一。临床上,新月形泪液是最常见的泪液形状。通过开发六个特定的样本，三维，具有非均质材料特性的冈上-冈下有限元模型，这项研究旨在检查由于标本特定的材料特性和肩袖撕裂大小，冈上肌腱的组织变形（最大主应变）的变化。具有中小型全厚度新月形泪液的FE模型在日常生活和理疗活动中会承受负荷。解剖了六个新鲜冷冻的尸体肩，以机械地测试冈上肌腱，并开发和验证可用于评估因小（<1cm，相当于肌腱宽度的20-30%）和中型（1-3厘米，相当于肌腱宽度的40-50％）位于冈上肌腱中部和后部的撕裂。检查了泪液尖端最大主应变的FE预测，以确定在日常生活活动（饮酒和刷牙）和理疗练习（俯卧外展和外旋90°外展）期间是否达到失效应变。对于中小型泪液，中后部泪液破坏载荷之间没有观察到显着差异。对于容易被绑架，对于冈上肌腱中部和后部的中等尺寸撕裂,存在撕裂进展(超过失效应变)的潜在风险.对于外展90°外旋,一个中间撕裂的模型和两个后面撕裂的模型经历了失败。对于所有日常活动负荷，应变从未超过失效应变。我们的三维冈上-冈下FE模型表明，根据区域应变响应，小眼泪似乎不太可能进展；然而，在更剧烈的理疗练习中，中型眼泪的风险更高。此外，患者特异性肌腱材料特性的差异对于确定撕裂是否会进展很重要.因此,基于泪液大小的患者特异性管理计划可能有利于改善临床结局.
