Department of Mechanical Engineering, The University of Texas at Austin, Austin, TX 78712, USA.
J Biomech. 2011 Feb 3;44(3):379-85. doi: 10.1016/j.jbiomech.2010.10.027. Epub 2010 Nov 11.
Unilateral, below-knee amputees have an increased risk of falling compared to non-amputees. The regulation of whole-body angular momentum is important for preventing falls, but little is known about how amputees regulate angular momentum during walking. This study analyzed three-dimensional, whole-body angular momentum at four walking speeds in 12 amputees and 10 non-amputees. The range of angular momentum in all planes significantly decreased with increasing walking speed for both groups. However, the range of frontal-plane angular momentum was greater in amputees compared to non-amputees at the first three walking speeds. This range was correlated with a reduced second vertical ground reaction force peak in both the intact and residual legs. In the sagittal plane, the amputee range of angular momentum in the first half of the residual leg gait cycle was significantly larger than in the non-amputees at the three highest speeds. In the second half of the gait cycle, the range of sagittal-plane angular momentum was significantly smaller in amputees compared to the non-amputees at all speeds. Correlation analyses suggested that the greater range of angular momentum in the first half of the amputee gait cycle is associated with reduced residual leg braking and that the smaller range of angular momentum in the second half of the gait cycle is associated with reduced residual leg propulsion. Thus, reducing residual leg braking appears to be a compensatory mechanism to help regulate sagittal-plane angular momentum over the gait cycle, but may lead to an increased risk of falling.
与非截肢者相比，单侧小腿截肢者跌倒的风险增加。全身角动量的调节对于预防跌倒很重要，但对于截肢者在行走过程中如何调节角动量知之甚少。本研究分析了 12 名截肢者和 10 名非截肢者在四种行走速度下的三维全身角动量。对于两组，所有平面的角动量范围都随着行走速度的增加而显著减小。然而，在前三步行速下，与非截肢者相比，截肢者的额状面角动量范围更大。这个范围与完整和残肢的第二垂直地面反作用力峰值的减少有关。在矢状面，在三个最高速度下，残肢步态周期前半部分的截肢者角动量范围明显大于非截肢者。在步态周期的后半部分，在所有速度下，截肢者的矢状面角动量范围明显小于非截肢者。相关分析表明，在截肢者步态周期的前半部分，角动量范围较大与残肢制动减少有关，而在后半部分，角动量范围较小与残肢推进减少有关。因此，减少残肢制动似乎是一种代偿机制，可以帮助调节步态周期中的矢状面角动量，但可能会增加跌倒的风险。
