Khandare Sujata, Arce Richard A, Vidt Meghan E
Biomedical Engineering, Pennsylvania State University, University Park, PA, USA.
College of Health Solutions, Arizona State University, Phoenix, AZ, USA.
J Electromyogr Kinesiol. 2022 Feb;62:102335. doi: 10.1016/j.jelekin.2019.07.005. Epub 2019 Jul 10.
Rotator cuff tear (RCT) in older adults may cause decreased muscle forces and disrupt the force balance at the glenohumeral joint, compromising joint stability. Our objective was to identify how increased RCT severity affects glenohumeral joint loading and muscle activation patterns using a computational model. Muscle volume measurements were used to scale a nominal upper limb model's peak isometric muscle forces to represent force-generating characteristics of an average older adult male. Increased RCT severity was represented by systematically decreasing peak isometric muscle forces of supraspinatus, infraspinatus, and subscapularis. Five static postures in both scapular and frontal planes were evaluated. Results revealed that in both scapular and frontal planes, the peak glenohumeral joint contact force magnitude remained relatively consistent across increased RCT severity (average 1.5% and -4.2% change, respectively), and a relative balance of the transverse force couple is maintained even in massive RCT models. Predicted muscle activations of intact muscles, like teres minor, increased (average 5-30% and 4-17% in scapular and frontal planes, respectively) with greater RCT severity. This suggests that the system is prioritizing glenohumeral joint stability, even with severe RCT, and that unaffected muscles play a compensatory role to help stabilize the joint.
老年人的肩袖撕裂（RCT）可能会导致肌肉力量下降，并破坏盂肱关节处的力平衡，进而损害关节稳定性。我们的目标是使用计算模型来确定RCT严重程度增加如何影响盂肱关节负荷和肌肉激活模式。肌肉体积测量用于按比例调整一个标称上肢模型的等长肌肉峰值力量，以代表一名普通老年男性的力量产生特征。通过系统性降低冈上肌、冈下肌和肩胛下肌的等长肌肉峰值力量来表示RCT严重程度增加。对肩胛平面和额状面的五种静态姿势进行了评估。结果显示，在肩胛平面和额状面中，随着RCT严重程度增加，盂肱关节接触力峰值大小相对保持一致（分别平均变化1.5%和 -4.2%），并且即使在严重RCT模型中，横向力偶也保持相对平衡。随着RCT严重程度增加，完整肌肉（如小圆肌）预测的肌肉激活增加（在肩胛平面和额状面中分别平均增加5 - 30%和4 - 17%）。这表明即使在严重RCT情况下，该系统也优先考虑盂肱关节稳定性，并且未受影响的肌肉起到补偿作用以帮助稳定关节。
