Virginia Tech-Wake Forest School of Biomedical Engineering and Sciences, Virginia Tech, Blacksburg, VA 24061, USA.
J Biomech. 2013 Jul 26;46(11):1907-12. doi: 10.1016/j.jbiomech.2013.04.018. Epub 2013 May 29.
Among persons with unilateral lower-limb amputation (LLA), proximal compensations and preferential use of the sound limb during gait and movement may lead to chronic alterations and/or asymmetries in trunk mechanical and neuromuscular behaviors. Trunk stiffness, the magnitude and timing of maximum reflex force, and EMG reflex delays of superficial trunk muscles, were estimated here using multidirectional (anteriorly- and laterally-directed) position-controlled horizontal trunk perturbations (±5mm, applied at T8) with the pelvis immobilized. Alterations and asymmetries in these trunk behaviors were quantified and compared among eight males with unilateral LLA, and eight male non-amputation controls. During anteriorly-directed perturbations, trunk stiffness and maximum reflex force were 24% and 23% lower, respectively, among participants with LLA compared to non-amputation controls, and the timing of maximum reflex force was 8% later. During lateral perturbations, trunk stiffness and maximum reflex force were also significantly lower among participants with LLA, by 22% and 27%, respectively. Bilateral asymmetries were present in trunk stiffness and the timing of maximum reflex force among persons with LLA. Specifically, trunk stiffness was 20% lower and timing of maximum reflex force was 9% later during perturbations involving spinal tissues and muscles ipsilateral to the side of amputation. Reduced and asymmetric trunk mechanical and neuromuscular behaviors may suggest a condition of reduced trunk stability among individuals with LLA, which could be due to repeated exposure to altered and asymmetric gait and movement and/or compensatory muscle recruitment in response to lost or altered musculature subsequent to LLA.
在单侧下肢截肢（LLA）人群中，在步态和运动过程中，近端代偿和对健康肢体的优先使用可能导致躯干机械和神经肌肉行为的慢性改变和/或不对称。这里使用多向（前后向和侧向）位置控制水平躯干扰动（±5mm，在 T8 施加）来估计躯干刚度、最大反射力的幅度和时间以及浅表躯干肌肉的 EMG 反射延迟，骨盆固定。在这些躯干行为中，对 8 名单侧 LLA 男性参与者和 8 名非截肢男性对照组进行了定量和比较。在前向扰动期间，LLA 参与者的躯干刚度和最大反射力分别比非截肢对照组低 24%和 23%，最大反射力的时间延迟 8%。在侧向扰动期间，LLA 参与者的躯干刚度和最大反射力也显著降低，分别降低了 22%和 27%。LLA 参与者的躯干刚度和最大反射力的双侧不对称。具体来说，在涉及到截肢侧同侧脊柱组织和肌肉的扰动中，躯干刚度降低了 20%，最大反射力的时间延迟了 9%。LLA 个体的躯干机械和神经肌肉行为的减少和不对称可能表明躯干稳定性降低，这可能是由于反复暴露于改变和不对称的步态和运动，以及/或由于 LLA 后失去或改变的肌肉导致的代偿性肌肉募集。
