A novel mechanics-based intervention to improve post-stroke gait stability

独立机动性，个人成功、安全地在其环境中导航的能力， 是生活质量的主要贡献者。不幸的是，中风后的机动性通常会降低，从而阻止 许多中风幸存者恢复到典型的活动参与水平。减少的主要贡献者 移动性是指步态不稳定，它可以通过增加跌倒的风险或通过增加恐惧来限制功能 坠落的恐惧。一些现有的康复技术已经被证明可以改善某些方面的康复 中风后的步态功能，如增加自选的行走速度。然而，这些干预措施已经 普遍未能解决步态不稳定问题，跌倒风险缺乏改善就是明证。一个可能的原因是 当前康复方法的有限有效性在于它们不是基于独特的 中风后步态不稳定的潜在机制。 这一总的研究路线的长期目标是开发临床可用的、基于机制的 改善中风后步态稳定性的干预措施。作为实现这一目标的一步，该项目将 关注通过研究步态的前期工作所暗示的潜在的不稳定的机制原因 在未受伤的对照组和中风幸存者中稳定下来。这种方法与典型的 步态不稳定，主要侧重于量化非因果的稳定性指标，而不是理解 潜在的机制。 中心假设是中风后步态稳定性的紊乱通常是由于缺乏 脚部放置位置的机械适当调整。而步态稳定的个体 根据他们重心的机械状态主动控制他们的脚的放置，这证明了 中风后往往缺乏主动稳定。典型的步态稳定策略的破坏 推动了最近建造的能够操纵脚的康复机器人装置的原型 放置位置。这项提议的目标是进一步开发该装置并进行初步测试 它能够改善中风后的步态稳定性，基于运动学习的原理。这将会实现的 通过三个具体目标。 第一个具体目标是确定能够有效地调节脚的最简单的力场控制方法 放置。将对几种候选控制方法进行比较，以提高它们的能力 机械上适当的脚部位置调节。第二个具体目标是确定 典型的步态稳定策略可以通过重复的步态练习来恢复，同时力场也可以：1) 鼓励机械地适当放置脚；或2)放大错误，使其远离机械地-- 适当的目标位置。这两种干预策略基于不同的理论框架。 “挑战点框架”表明，由力场提供的机械协助可能允许 中风幸存者可以体验(并重新学习)他们原本可能无法完成的运动模式。 相反，“误差驱动的适应”框架表明，放大的运动学误差可能会驱动 参与者积极抵抗这些力量，在脚部放置时产生有益的后遗症。第三 具体目标将量化患者基线特征和剂量对干预的影响 效果，为未来更大规模的试验提供必要的数据。 建议的项目基于人体步态力学和运动学的综合理论框架。 学习，并将使用一种新的力场来量化基于机制的干预的潜力 中风幸存者的典型神经机械步态稳定策略。由此产生的知识具有 有可能对制定更大规模的康复范例作出重要贡献 哪些治疗干预措施针对患者的特定限制。

Independent mobility, the ability of an individual to successfully and safely navigate through their environment, is a primary contributor to quality of life. Unfortunately, mobility often decreases following a stroke, preventing many stroke survivors from returning to typical levels of activity participation. A major contributor to reduced mobility is gait instability, which can limit function either by increasing the risk of falls or by increasing the fear of falling. Several existing rehabilitation techniques have been demonstrated to improve certain aspects of post-stroke gait function, such as increasing self-selected walking speed. However, these interventions have generally failed to address gait instability, as evidenced by a lack of improvement in fall risk. A likely reason for the limited effectiveness of current rehabilitation approaches is that they are not based on the unique mechanisms underlying post-stroke gait instability. A longer-term goal of this general line of research is to develop clinically-available, mechanism-based interventions to improve post-stroke gait stability. As a step toward accomplishing this goal, the project will focus on a potential mechanistic cause of instability suggested by preliminary work investigating how gait is stabilized among uninjured controls and stroke survivors. This approach contrasts with typical investigations of gait instability, which largely focus on quantifying non-causal indicators of stability rather than understanding the underlying mechanisms. The central hypothesis is that post-stroke disruptions in gait stability are often caused by a lack of mechanically-appropriate adjustments in foot placement location. While individuals with stable gait patterns actively control their foot placement based on the mechanical state of their center of mass, this evidence of active stabilization is often lacking after a stroke. The disruption of the typical gait stabilization strategy has motivated the recent construction of a prototype rehabilitation robotics device able to manipulate foot placement location. The objective of this proposal is to further develop this device and conduct initial testing of its ability to improve post-stroke gait stability, based on principles of motor learning. This will be accomplished through three Specific Aims. The first Specific Aim is to identify the simplest force-field control method able to effectively modulate foot placement. Several candidate control methods will be compared in terms of their ability to increase mechanically-appropriate foot placement modulation. The second Specific Aim is to determine whether the typical gait stabilization strategy can be restored by repeated gait practice while the force-field either: 1) encourages mechanically-appropriate foot placement; or 2) amplifies errors away from mechanically- appropriate target locations. These two intervention strategies are based on distinct theoretical frameworks. The “challenge point framework” suggests that mechanical assistance provided by the force-field may allow stroke survivors to experience (and relearn) a movement pattern they may otherwise be unable to accomplish. In contrast, the “error-driven adaptation” framework suggests that amplified kinematic errors may drive participants to actively resist these forces, producing beneficial after-effects in foot placement. The third Specific Aim will quantify the effects of patient baseline characteristics and dosage on the intervention’s effects, necessary data for future larger-scale trials. The proposed project is based on the combined theoretical frameworks of human gait mechanics and motor learning, and will quantify the potential of mechanism-based interventions using a novel force-field to restore the typical neuromechanical gait stabilization strategy in stroke survivors. The resultant knowledge has the potential to make an important contribution to the development of a larger-scale rehabilitation paradigm in which therapeutic interventions are targeted to a patient’s specific limitations.