Department of Mechanical Engineering, Stanford University, Stanford, CA, USA.
Gait Posture. 2013 May;38(1):86-91. doi: 10.1016/j.gaitpost.2012.10.019. Epub 2012 Nov 27.
The goals of this study were to determine if the muscle contributions to vertical and fore-aft acceleration of the mass center differ between crouch gait and unimpaired gait and if these muscle contributions change with crouch severity. Examining muscle contributions to mass center acceleration provides insight into the roles of individual muscles during gait and can provide guidance for treatment planning. We calculated vertical and fore-aft accelerations using musculoskeletal simulations of typically developing children and children with cerebral palsy and crouch gait. Analysis of these simulations revealed that during unimpaired gait the quadriceps produce large upward and backward accelerations during early stance, whereas the ankle plantarflexors produce large upward and forward accelerations later in stance. In contrast, during crouch gait, the quadriceps and ankle plantarflexors produce large, opposing fore-aft accelerations throughout stance. The quadriceps force required to accelerate the mass center upward was significantly larger in crouch gait than in unimpaired gait and increased with crouch severity. The gluteus medius accelerated the mass center upward during midstance in unimpaired gait; however, during crouch gait the upward acceleration produced by the gluteus medius was significantly reduced. During unimpaired gait the quadriceps and ankle plantarflexors accelerate the mass center at different times, efficiently modulating fore-aft accelerations. However, during crouch gait, the quadriceps and ankle plantarflexors produce fore-aft accelerations at the same time and the opposing fore-aft accelerations generated by these muscles contribute to the inefficiency of crouch gait.
本研究旨在确定在蹲姿步态和正常步态中，质心垂直和前后方向加速度的肌肉贡献是否存在差异，以及这些肌肉贡献是否随蹲姿严重程度而变化。研究质心加速度的肌肉贡献可以深入了解个体肌肉在步态中的作用，并为治疗方案提供指导。我们使用发育正常的儿童和脑瘫儿童的肌肉骨骼仿真来计算质心的垂直和前后加速度。对这些模拟的分析表明，在正常步态中，股四头肌在早期站立时产生较大的向上和向后加速度，而踝关节跖屈肌在站立后期产生较大的向上和向前加速度。相比之下，在蹲姿步态中，股四头肌和踝关节跖屈肌在整个站立过程中产生较大的相反的前后加速度。在蹲姿步态中，使质心向上加速所需的股四头肌力明显大于正常步态，并且随着蹲姿严重程度的增加而增加。在正常步态中，臀中肌在中站立时使质心向上加速；然而，在蹲姿步态中，臀中肌产生的向上加速度明显降低。在正常步态中，股四头肌和踝关节跖屈肌在不同时间加速质心，有效地调节前后加速度。然而，在蹲姿步态中，股四头肌和踝关节跖屈肌同时产生前后加速度，这些肌肉产生的相反的前后加速度导致蹲姿步态效率低下。
