Gait impairment is a common complication of multiple sclerosis (MS). Gait limitations such as limited hip flexion, foot drop, and knee hyperextension often require external devices like crutches, canes, and orthoses. The effects of mobility-assistive technologies (MATs) prescribed to people with MS are not well understood, and current devices do not cater to the specific needs of these individuals. To address this, a passive unilateral hip flexion-assisting orthosis (HFO) was developed that uses resistance bands spanning the hip joint to redirect energy in the gait cycle. The purpose of this study was to investigate the short-term effects of the HFO on gait mechanics and muscle activation for people with and without MS. We hypothesized that (1) hip flexion would increase in the limb wearing the device, and (2) that muscle activity would increase in hip extensors, and decrease in hip flexors and plantar flexors. Five healthy subjects and five subjects with MS walked for minute-long sessions with the device using three different levels of band stiffness. We analyzed peak hip flexion and extension angles, lower limb joint work, and muscle activity in eight muscles on the lower limbs and trunk. Single-subjects analysis was used due to inter-subject variability. For subjects with MS, the HFO caused an increase in peak hip flexion angle and a decrease in peak hip extension angle, confirming our first hypothesis. Healthy subjects showed less pronounced kinematic changes when using the device. Power generated at the hip was increased in most subjects while using the HFO. The second hypothesis was not confirmed, as muscle activity showed inconsistent results, however several subjects demonstrated increased hip extensor and trunk muscle activity with the HFO. This exploratory study showed that the HFO was well-tolerated by healthy subjects and subjects with MS, and that it promoted more normative kinematics at the hip for those with MS. Future studies with longer exposure to the HFO and personalized assistance parameters are needed to understand the efficacy of the HFO for mobility assistance and rehabilitation for people with MS.

中文翻译：

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对患有和不患有多发性硬化症的个体进行无动力髋关节屈曲矫形器的生物力学分析

步态障碍是多发性硬化症（MS）的常见并发症。髋部屈曲受限、足下垂和膝关节过度伸展等步态限制通常需要拐杖、手杖和矫形器等外部设备。移动辅助技术 (MAT) 对多发性硬化症患者的影响尚不清楚，并且当前的设备无法满足这些人的特定需求。为了解决这个问题，开发了一种被动单侧髋关节屈曲辅助矫形器（HFO），它使用横跨髋关节的阻力带来重定向步态周期中的能量。本研究的目的是调查 HFO 对患有和未患有多发性硬化症的人的步态力学和肌肉激活的短期影响。我们假设（1）佩戴该设备的肢体的髋部屈曲会增加，（2）髋部伸肌的肌肉活动会增加，髋部屈肌和跖屈肌的肌肉活动会减少。五名健康​​受试者和五名患有多发性硬化症的受试者使用三种不同级别的带硬度的设备步行一分钟。我们分析了髋部屈曲和伸展的峰值角度、下肢关节工作以及下肢和躯干八块肌肉的肌肉活动。由于受试者间的差异，使用了单个受试者分析。对于患有多发性硬化症的受试者，HFO 导致髋部屈曲峰值角度增加和髋部伸展峰值角度减小，证实了我们的第一个假设。健康受试者在使用该设备时表现出不太明显的运动变化。使用 HFO 时，大多数受试者臀部产生的功率有所增加。第二个假设并未得到证实，因为肌肉活动显示出不一致的结果，但一些受试者表现出 HFO 增加了髋部伸肌和躯干肌肉活动。这项探索性研究表明，健康受试者和多发性硬化症受试者对 HFO 的耐受性良好，并且它可以促进多发性硬化症患者的髋部运动更加规范。未来需要进行更长时间接触 HFO 和个性化辅助参数的研究，以了解 HFO 对多发性硬化症患者的行动辅助和康复的功效。