Department of Biomechanical Engineering, Delft University of Technology, Delft, The Netherlands.
PLoS One. 2010 Feb 17;5(2):e9307. doi: 10.1371/journal.pone.0009307.
Humans normally dissipate significant energy during walking, largely at the transitions between steps. The ankle then acts to restore energy during push-off, which may be the reason that ankle impairment nearly always leads to poorer walking economy. The replacement of lost energy is necessary for steady gait, in which mechanical energy is constant on average, external dissipation is negligible, and no net work is performed over a stride. However, dissipation and replacement by muscles might not be necessary if energy were instead captured and reused by an assistive device.
METHODOLOGY/PRINCIPAL FINDINGS: We developed a microprocessor-controlled artificial foot that captures some of the energy that is normally dissipated by the leg and "recycles" it as positive ankle work. In tests on subjects walking with an artificially-impaired ankle, a conventional prosthesis reduced ankle push-off work and increased net metabolic energy expenditure by 23% compared to normal walking. Energy recycling restored ankle push-off to normal and reduced the net metabolic energy penalty to 14%.
CONCLUSIONS/SIGNIFICANCE: These results suggest that reduced ankle push-off contributes to the increased metabolic energy expenditure accompanying ankle impairments, and demonstrate that energy recycling can be used to reduce such cost.
人类在行走过程中会消耗大量能量，主要是在步幅之间的转换过程中。踝关节在蹬离过程中起到恢复能量的作用，这可能是踝关节损伤几乎总是导致较差步行经济性的原因。为了保持稳定的步态，需要替换失去的能量，在稳定的步态中，机械能平均保持不变，外部耗散可以忽略不计，在一个步幅中不做功。然而，如果能量被辅助设备捕获并重复使用，肌肉的耗散和补充可能就不是必需的。
方法/主要发现：我们开发了一种微处理器控制的人工脚，可以捕获腿部正常耗散的部分能量，并将其“回收”为正的踝关节功。在对踝关节受损的受试者进行的测试中，与正常行走相比，传统的假肢减少了踝关节蹬离功，使净代谢能量消耗增加了 23%。能量回收使踝关节蹬离恢复正常，使净代谢能量消耗的惩罚降低到 14%。
结论/意义：这些结果表明，踝关节蹬离的减少导致了踝关节损伤时代谢能量消耗的增加，并证明了能量回收可以用于降低这种成本。
