Leonardis Joshua M, Desmet David M, Lipps David B
School of Kinesiology, University of Michigan, Ann Arbor, MI 48109, United States.
School of Kinesiology, University of Michigan, Ann Arbor, MI 48109, United States; Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI 48109, United States.
J Biomech. 2017 Oct 3;63:41-46. doi: 10.1016/j.jbiomech.2017.07.031. Epub 2017 Aug 10.
The sternocostal and clavicular regions of the pectoralis major are independently harvested to provide shoulder stability, but surgical decision making does not consider the biomechanical consequences that disinsertion of one fiber region over the other has on shoulder function. Differences in material properties between the fiber regions could influence which tissue is more optimal for surgical harvesting. The current study utilized ultrasound shear wave elastography (SWE) to investigate whether the in vivo material properties differ between the fiber regions. Shear wave velocities (SWVs) were collected from the sternocostal and clavicular fiber regions of the pectoralis major from ten healthy young male participants. Participants produced isometric shoulder torques of varying magnitudes (passive, 15%, and 30% MVC) and directions (horizontal and vertical adduction). Four shoulder positions encompassing different vertical abduction and external rotation angles were examined. One-way ANOVAs tested the hypotheses that differences in SWVs during rest existed between the fiber regions asa function of shoulder position, and differences in SWVs during contraction existed asa function of shoulder position and torque direction. In all shoulder positions, the clavicular region exhibited greater SWVs during rest than the sternocostal region (P<0.001). In shoulder positions that did not include external rotation, the clavicular region exhibited greater SWVs during contraction when producing horizontal adduction torques (P<0.001), while the sternocostal region exhibited greater SWVs during contraction when producing vertical adduction torques at 30% MVC (P<0.01). Our results suggest that each fiber region of the pectoralis major provides unique contributions to passive and active shoulder function.
胸大肌的胸骨部和锁骨部可独立获取以提供肩部稳定性，但手术决策并未考虑一个纤维区域相对于另一个纤维区域的离断对肩部功能产生的生物力学后果。纤维区域之间材料特性的差异可能会影响哪个组织更适合手术获取。本研究利用超声剪切波弹性成像（SWE）来研究纤维区域之间的体内材料特性是否存在差异。从十名健康年轻男性参与者的胸大肌胸骨纤维区域和锁骨纤维区域收集剪切波速度（SWV）。参与者产生不同大小（被动、15%和30%最大自主收缩）和方向（水平和垂直内收）的等长肩部扭矩。检查了包含不同垂直外展和外旋角度的四个肩部位置。单因素方差分析检验了以下假设：休息时纤维区域之间SWV的差异作为肩部位置的函数存在，收缩时SWV的差异作为肩部位置和扭矩方向的函数存在。在所有肩部位置，休息时锁骨区域的SWV均高于胸骨区域（P<0.001）。在不包括外旋的肩部位置，产生水平内收扭矩时，锁骨区域在收缩时的SWV更大（P<0.001），而在30%最大自主收缩时产生垂直内收扭矩时，胸骨区域在收缩时的SWV更大（P<0.01）。我们的结果表明，胸大肌的每个纤维区域对被动和主动肩部功能都有独特的贡献。
