IEEE Trans Neural Syst Rehabil Eng. 2020 Apr;28(4):1022-1031. doi: 10.1109/TNSRE.2020.2972206. Epub 2020 Mar 5.
We characterized the passive mechanical properties of the affected and contralateral musculotendon units in 9 chronic stroke survivors as well as in 6 neurologically-intact controls. Using a position-controlled motor, we precisely indented the distal tendon of the biceps brachii to a 20 mm depth from skin, recording both its sagittal motion using ultrasound movies and the compression force at the tip of the indenter. Length changes of 8 equally-spaced features along the aponeurosis axis were quantified using a pixel-tracking protocol. We report that, on the aggregate and with respect to contralateral and control, respectively, the affected side initiates feature motion at a shorter indentation distance by 61% and 50%, travels further by 15% and 9%, at a lower rate of 28% and 15%, and is stiffer by 40% and 57%. In an extended analysis including the spatial location of the 8 designated features, we report that in contrast to the contralateral and control muscles, the affected musculotendon unit does not strain measurably within the imaging window. These results confirm that chronic stroke-induced spasticity changes musculotendon unit passive mechanics, causing it to not strain under stretch. The mechanisms responsible for altered passive mechanics may lie within extracellular matrix fibrosis.
我们对 9 名慢性脑卒中幸存者和 6 名神经正常的对照者的患侧和对侧肌肉肌腱单位的被动机械特性进行了特征描述。使用位置控制电机，我们将肱二头肌的远端肌腱从皮肤精确地压入 20 毫米深度，使用超声电影记录其矢状运动，并记录压入尖端的压缩力。使用像素跟踪协议对沿腱膜轴的 8 个等距特征的长度变化进行了量化。我们报告说，与对侧和对照组相比，患侧的特征运动起始于更短的压入距离，分别为 61%和 50%，运动距离更长，分别为 15%和 9%，速度更慢，分别为 28%和 15%，刚性更高，分别为 40%和 57%。在包括 8 个指定特征的空间位置的扩展分析中，我们报告说，与对侧和对照组肌肉相比，患侧肌肉肌腱单位在成像窗口内没有可测量的应变。这些结果证实，慢性卒中引起的痉挛改变了肌肉肌腱单位的被动力学特性，使其在拉伸下不会产生应变。改变被动力学的机制可能存在于细胞外基质纤维化中。
