Background

Many studies on ankle-foot orthoses investigated the optimal stiffness around the ankle, while the effect of footplate stiffness has been largely ignored. This study investigated the effects of ankle-foot orthosis footplate stiffness on ankle-foot push-off power during walking in able-bodied persons.

Methods

Twelve healthy participants walked at a fixed speed (1.25 m·s⁻¹) on an instrumented treadmill in four conditions: shod and with a posterior leaf-spring orthosis with a flexible, stiff or rigid footplate. For each trial, ankle kinematics and kinetics were averaged over one-minute walking. Separate contributions of the ankle joint complex and distal hindfoot to total ankle-foot power and work were calculated using a deformable foot model.

Findings

Peak ankle joint power was significantly higher with the rigid footplate compared to the flexible and stiff footplate and not different from shod walking. The stiff footplate increased peak hindfoot power compared to the flexible and rigid footplate and shod walking. Total ankle-foot power showed a significant increase with increasing footplate stiffness, where walking with the rigid footplate was comparable to shod walking. Similar effects were found for positive mechanical work.

Interpretation

A rigid footplate increases the lever of the foot, resulting in an increased ankle moment and energy storage and release of the orthosis' posterior leaf-spring as reflected in higher ankle joint power. This effect dominates the power generation of the foot, which was highest with the intermediate footplate stiffness. Future studies should focus on how tuning footplate stiffness could contribute to optimizing ankle-foot orthosis efficacy in clinical populations.

中文翻译：

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后板弹簧踝足矫形器行走时踏板刚度对推力的影响

背景

许多关于踝足矫形器的研究调查了踝关节周围的最佳刚度，而足板刚度的影响在很大程度上被忽略了。本研究调查了健壮者行走时踝足矫形器踏板刚度对踝足蹬地力的影响。

方法

12 名健康参与者以固定速度 (1.25 m·s ^-1 ) 在仪表跑步机上以四种条件行走：穿鞋并使用带有柔性、刚性或刚性踏板的后板簧矫形器。对于每个试验，脚踝运动学和动力学平均超过一分钟的步行。使用可变形足模型计算踝关节复合体和后足远端对总踝足功率和功的单独贡献。

发现

与灵活和僵硬的踏板相比，刚性踏板的峰值踝关节功率显着更高，并且与穿鞋行走没有区别。与灵活和刚性的脚踏板和穿鞋行走相比，坚硬的脚踏板增加了峰值后足力量。随着踏板刚度的增加，踝足总功率显着增加，其中使用刚性踏板行走与穿鞋行走相当。对积极的机械功也发现了类似的效果。

解释

刚性脚踏板增加了足部的杠杆作用，从而增加了踝关节力矩以及矫形器后部板簧的能量储存和释放，这反映在更高的踝关节力量上。这种效应在足部的发电中占主导地位，中间踏板刚度最高。未来的研究应集中在调整踏板刚度如何有助于优化临床人群中的踝足矫形器疗效。