Hybrid Neuroprosthesis with a Variable Knee for Walking in SCI

描述(由申请人提供)： 本研究的目的是确定一种结合功能性神经肌肉刺激(FNS)和基于先进传感器的可控可变阻抗膝关节机构(VIKM)的新型混合型神经假体(HNP)能否用于脊髓损伤(SCI)截瘫患者的步行：(1)减少负荷过程中的冲击力，改善前进动量，减少躯干垂直运动的波动，并改善步行过程中的脚-地间隙；(2)通过控制膝关节屈曲阻力来恢复楼梯下降和站立功能。研究计划和方法-研究的三个阶段是：1)设计、开发和验证使用我们的新型可变阻抗膝关节机构(VIKM)来调节步态中站立阶段膝关节屈曲的闭环控制系统，2)评估在步态站立阶段结合膝关节屈曲的功能益处，以及3)评估VIKM控制楼梯下降和站立到坐的动作的能力。五名来自SCI的胸部截瘫患者将被招募来测试VIKM，作为混合神经假体(HNP)的一部分。受试者将植入一个八通道脉冲发生器和肌肉内电极，以激活髂腰肌/缝匠肌用于髋关节/膝关节屈曲，腿筋用于伸臀和股四头肌用于伸膝和腓肠肌用于足底屈曲。这些肌肉是站立、启动挥杆和身体向前推进的关键肌肉。踝关节将会弹跳 在主动足底屈曲推开后，在挥杆过程中将脚放回中立位。一个原型的VIKM将被整合到先前设计的外骨骼中，并与植入的FNS系统相结合，产生一种新型的HNP。在步态过程中调节膝盖的闭环控制器将基于传感器的反馈，这些传感器测量脚部与地面的接触、臀部和膝部角度、大腿和腿部的速度以及加速度。微控制器将根据步态周期的相位来调节阻尼器电流来控制VIKM的阻力。有限状态控制器 将控制VIKM并调节对瘫痪肌肉的刺激。将首先对其进行评估 在两个健全的个体中，以确保它可以准确地识别步态的阶段(控制器 验证)，并提供足够的抵抗力，防止膝关节在站立时崩溃(VIKM验证)。VIKM有望通过调节膝关节屈曲，在初始负荷时减轻冲击和吸收冲击的影响，减少身体质心位移，并在早期挥杆时改善脚趾间隙。在楼梯下降和站立到坐姿动作中，重点将放在身体的下降和重量的接受上，届时VIKM将执行通常由FNS无法控制的偏心收缩肌肉执行的大部分工作。控制器将进行优化，以减少在下降和降落在台阶下方和坐面时对上肢支撑的需求。使用基于VIKM的HNP行走将与仅使用FNS和传统矫形器行走进行比较。数据的统计分析将使用受试者内的实验设计来检验VIKM的效果。冲击力 在初始接触时，将测量身体重心的平均垂直运动和站立阶段的膝关节屈曲。将使用单向重复测量ANOVA来检验显著差异，并将使用Tukey诚实显着差异多重比较测试来确定95%的可信区间。

DESCRIPTION (provided by applicant): Objective - of the proposed research is to determine whether a novel hybrid neuroprosthesis (HNP) combining functional neuromuscular stimulation (FNS) and incorporating an advanced sensor based controlled variable impedance knee mechanism (VIKM) for walking in persons with paraplegia from spinal cord injury (SCI) can: (1) reduce impact forces during loading, improve forward momentum, reduce the fluctuations in vertical trunk motion, and improve foot-ground clearance during walking, and (2) restore stair descent and stand-to-sit functions by controlling the resistance to knee flexion while lowering of the body. Research Plan and Methodology - Three phases of the study are: 1) design, development, and validation of a closed loop control system using our novel variable impedance knee mechanism (VIKM) for modulation of stance phase knee flexion during gait, 2) evaluation of the functional benefits of incorporating knee flexion during stance phase of gait, and 3) evaluation of the ability of the VIKM to control stair descent and stand-to-sit maneuver. Five individuals with thoracic paraplegia from SCI will be recruited to test the VIKM as part of a hybrid neuroprosthesis (HNP). Subjects will be implanted with an eight channel pulse generator and intramuscular electrodes to activate iliopsoas/sartorius for hip/knee flexion, hamstrings for hip extension and quadriceps for knee extension and gastrocnemius for plantar flexion. These are key muscles for standing up, for initiating the swing and for forward propulsion of the body. The ankle joint will be spring loaded to return the foot to neutral during swing after actively plantar flexing for push-off. A prototype VIKM will be incorporated in previously designed exoskeleton and combined with implanted FNS systems to yield a novel HNP. A closed loop controller to modulate knee during gait will be based on feedback from sensors measuring foot-ground contact, hip and knee angles, thigh and leg velocity, and acceleration. A microcontroller will modulate damper current to control the resistance of the VIKM based on phase of the gait cycle. The finite state controller will control the VIKM and modulate stimulation to the paralyzed muscles. It will be first evaluated in two able-bodied individuals to ensure that it can accurately identify phases of gait (controller validation) and provide adequate resistance against knee collapse during stance (VIKM validation). The VIKM is expected to lessen the effect of impact and absorb shock during initial loading, reduce body center of mass displacement and improve toe clearance in early swing by regulating knee flexion. During stair descent and stand-to-sit maneuver the emphasis will be on lowering of the body and weight acceptance when the VIKM will perform most of the work normally performed by the eccentrically contracting muscles impossible to control with FNS. The controller will be optimized to reduce the need for upper extremity support during lowering and landing on the step below and sitting surface. Walking with the VIKM-based HNP will be compared to walking with FNS-only and conventional orthosis. Statistical analysis of the data will be carried out using a within subject experimental design to test effect of VIKM. Impact force at initial contact, average vertical motion of body center of mass, and stance phase knee flexion will be measured. A one-way repeated measure ANOVA will be used to test for significant differences and the Tukey honestly significant difference multiple comparison tests will be used to determine 95% confidence intervals.