Biomechanical mechanisms underlying exosuit-induced improvements in walking economy after stroke
Biomechanical mechanisms underlying exosuit-induced improvements in walking economy after stroke
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DOI：
10.1242/jeb.168815
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发表时间：
2018-03-01
影响因子：
2.8
通讯作者：
Walsh, Conor J.
中科院分区：
文献类型：
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作者：
Bae, Jaehyun;Awad, Louis N.;Walsh, Conor J.
卒中导致的偏瘫步态具有不对称和代谢代价高的特点。瘫痪脚踝的虚弱和控制受损导致向前推进和离地行走的子任务减少，这对安全和有效的运动至关重要。因此，有必要进行有针对性的步态干预，以改善中风后偏瘫的踝关节功能。我们已经开发了基于纺织品的软可穿戴机器人，它使用Bowden缆线(软外衣)将非机载或身体穿戴的执行器产生的机械能量传输到偏瘫的脚踝，并证明外衣可以克服偏瘫肢体向前推进和离地间隙方面的缺陷，最终降低偏瘫行走的代谢成本。这项研究阐明了外源性糖皮质激素导致代谢能力降低的生物力学机制。我们评估了Exosuit引起的每条肢体产生的身体重心功率(COM功率)、个人关节功率和代谢功率之间的关系。与无动力外衣步行相比，外衣辅助在步步过渡的关键时期产生了更多对称的COM发电(对称性增加22.4+/-6.4%)。患肢关节屈光度的变化与偏瘫患者(R2=0.83，P=0.004)和非偏瘫患者(R2=0.73，P=0.014)踝关节屈光度的变化有关。有趣的是，尽管Exosuit只对偏瘫肢体提供直接帮助，但代谢功率的变化与非偏瘫肢体COM功率的变化有关(R2=0.8，P=0.007)，而与偏瘫肢体COM功率的变化无关(P>；0.05)。这些发现有助于从根本上理解中风后的个体如何与外衣相互作用，以降低偏瘫行走的代谢成本。
Stroke-induced hemiparetic gait is characteristically asymmetric and metabolically expensive. Weakness and impaired control of the paretic ankle contribute to reduced forward propulsion and ground clearance - walking subtasks critical for safe and efficient locomotion. Targeted gait interventions that improve paretic ankle function after stroke are therefore warranted. We have developed textile-based, soft wearable robots that transmit mechanical power generated by off-board or body-worn actuators to the paretic ankle using Bowden cables (soft exosuits) and have demonstrated the exosuits can overcome deficits in paretic limb forward propulsion and ground clearance, ultimately reducing the metabolic cost of hemiparetic walking. This study elucidates the biomechanical mechanisms underlying exosuit-induced reductions in metabolic power. We evaluated the relationships between exosuit-induced changes in the body center of mass (COM) power generated by each limb, individual joint power and metabolic power. Compared with walking with an exosuit unpowered, exosuit assistance produced more symmetrical COM power generation during the critical period of the step-to-step transition (22.4 +/- 6.4% more symmetric). Changes in individual limb COM power were related to changes in paretic (R-2=0.83, P=0.004) and non-paretic (R-2=0.73, P=0.014) ankle power. Interestingly, despite the exosuit providing direct assistance to only the paretic limb, changes in metabolic power were related to changes in non-paretic limb COM power (R-2=0.80, P=0.007), not paretic limb COM power (P>0.05). These findings contribute to a fundamental understanding of how individuals post-stroke interact with an exosuit to reduce the metabolic cost of hemiparetic walking.