Due to disrupted motor and proprioceptive function, lower limb amputation imposes considerable challenges associated with balance and greatly increases risk of falling in presence of perturbations during walking. The aim of this study was to investigate dynamic balancing responses in unilateral transtibial amputees when they were subjected to perturbing pushes to the pelvis in outward direction at the time of foot strike on their non-amputated and amputated side during slow walking. Fourteen subjects with unilateral transtibial amputation and nine control subjects participated in the study. They were subjected to perturbations that were delivered to the pelvis at the time of foot strike of either the left or right leg. We recorded trajectories of center of pressure and center of mass, durations of in-stance and stepping periods as well as ground reaction forces. Statistical analysis was performed to determine significant differences in dynamic balancing responses between control subjects and subjects with amputation when subjected to outward-directed perturbation upon entering stance phases on their non-amputated or amputated sides. When outward-directed perturbations were delivered at the time of foot strike of the non-amputated leg, subjects with amputation were able to modulate center of pressure and ground reaction force similarly as control subjects which indicates application of in-stance balancing strategies. On the other hand, there was a complete lack of in-stance response when perturbations were delivered when the amputated leg entered the stance phase. Subjects with amputations instead used the stepping strategy and adjusted placement of the non-amputated leg in the ensuing stance phase to make a cross-step. Such response resulted in significantly larger displacement of center of mass. Results of this study suggest that due to the absence of the COP modulation mechanism, which is normally supplied by ankle motor function, people with unilateral transtibial amputation are compelled to choose the stepping strategy over in-stance strategy when they are subjected to outward-directed perturbation on the amputated side. However, the stepping response is less efficient than in-stance response.

中文翻译：

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单侧胫骨截肢者在跑步机缓慢行走过程中受到向外扰动后的动态平衡反应对于截肢侧和非截肢侧有很大差异

由于运动和本体感觉功能受损，下肢截肢给平衡带来了相当大的挑战，并且大大增加了行走过程中出现干扰时跌倒的风险。本研究的目的是调查单侧胫骨截肢者在缓慢行走过程中，在非截肢侧和截肢侧的脚踩地时，骨盆受到向外方向的扰动推力时的动态平衡反应。十四名单侧经胫骨截肢受试者和九名对照受试者参加了该研究。当左腿或右腿触地时，他们会受到传递到骨盆的扰动。我们记录了压力中心和质心的轨迹、实例和步进周期的持续时间以及地面反作用力。进行统计分析以确定对照受试者和截肢受试者在未截肢或截肢侧进入站立阶段时受到外向扰动时动态平衡反应的显着差异。当在非截肢腿的足部撞击时传递向外的扰动时，截肢受试者能够与对照受试者类似地调节压力中心和地面反作用力，这表明应用了实例平衡策略。另一方面，当截肢进入站立阶段时施加扰动时，完全缺乏即时反应。截肢的受试者则使用迈步策略，并在随后的站立阶段调整未截肢腿的位置来进行交叉步。这种响应导致质心的位移明显更大。这项研究的结果表明，由于缺乏通常由踝关节运动功能提供的 COP 调节机制，单侧胫骨截肢患者在受到外向运动时被迫选择迈步策略而不是站立策略。截肢侧的扰动。然而，步进响应的效率低于实例响应。