Postural control in hemiparetic patients during walking

研究了人体步态中快速终止和转身的机制。正常受试者和偏瘫患者被要求在感觉到腓浅神经受到电刺激时立即停止行走或转向指示方向。在正常受试者中，臀中肌还有一种额外的活动，用于旋转躯干。这种活动与另一只脚撞击的时间密切相关，与施加刺激时步态周期的阶段无关。当在步态周期的特定阶段应用停止或转弯的提示时，正常受试者必须用一小步来刹车向前的动量。但偏瘫患者由于步态速度较慢以及拐杖的使用，可以在不使用步态策略的情况下停止或转身。基于这些结果，我们进行了足部压力和运动学分析，以确定正常人和偏瘫患者戴着踝足矫形器(AFOS)行走时的运动控制策略。与踝关节固定程度无关，正常人足底表面(AFO内侧)上的足底压力中心在矢状面上从脚跟区域几乎线性地移动到脚趾。研究发现，站姿阶段膝关节运动的控制对AFO步行时的平稳重心转移起着至关重要的作用。另一方面，一些偏瘫患者在站立阶段的早期足部压力中心出现了后移。当穿着直立较短的鞋角AFO时，它变得更大了。由鞋垫传感器系统评估的足底压力在矢状面上的轨迹似乎有助于确定AFO对人体步态动态方面的影响。

The mechanism involved in rapidly terminating and turning during human gait were studied. Normal subjects and hemiparetic patients were asked to stop walking or to turn toward the instructed direction as soon as they felt an electrical stimulus to the superficial peroneal nerve. In the normal subjects, there was an additional activity of gluteus medius for rotating the trunk. This activity was closely related to the timing of the opposite foot strike, independent of the phase of the gait cycle when the stimulus was applied. When a cue to stop or turn was applied during certain phases of the gait cycle, the normal subjects had to use a short step for braking the forward momentum. But the hemiparetic patients could stop or turn without using a stepping strategy because of their slower gait speed as well as cane usage.Based on these results, foot pressure and kinematic analyses were performed to identify the strategies for motor control when normal subjects and hemiparetic patients walk while wearing ankle-foot orthoses (AFOs). Independent of the degree of ankle fixation, the center of foot pressures on the plantar surface (inside of AFO) in normal subjects almost linearly moved from heel region to toe in the sagittal plane. We found that the control of knee movement during the stance phase played a crucial role in the smooth weight shift during walking with an AFO.On the other hand, a backward shifting of the center of foot pressures during early stance phase was observed in some hemiparetic patients. It became larger when wearing a shoehorn AFO with a shorter upright. The trajectories of foot pressures in the sagittal plane that are evaluated by an insole sensor system seem to be useful for making sure of the effects of AFOs on dynamic aspects of human gait.