Jesse Brown VA Medical Center, Chicago, IL, USA; Northwestern University Prosthetics-Orthotics Center, Dept. of Physical Medicine & Rehabilitation, Feinberg School of Medicine, Chicago, IL, USA.
Northwestern University, Department of Biomedical Engineering, Evanston, IL, USA.
J Electromyogr Kinesiol. 2019 Oct;48:145-151. doi: 10.1016/j.jelekin.2019.07.012. Epub 2019 Jul 23.
Persons with upper limb loss (ULL) experience a high prevalence of falls, with the majority of falls occurring when walking. This issue may be related to altered arm dynamics, which play an important role in proactive mechanisms of locomotor stability. This study investigated effects of ULL and prosthesis use on proactive stability mechanisms, particularly if matching the mass and inertia of the impaired limb to the sound limb would enhance locomotor stability. Gait data were collected on adults with unilateral ULL during level walking while: (1) not wearing a prosthesis, (2) wearing their customary prosthesis, (3) wearing a mock prosthesis that matched the sound limb mass and inertia. Main and interaction effects of limb side and condition on trunk rotations, arm swing, step width, free vertical moment, and margin-of-stability were analyzed. Across conditions, arm swing, free vertical moment, and margin-of-stability were 2.27, 1.13, and 1.20 times greater, respectively, on the sound limb side than the impaired limb side. Persons with ULL display asymmetry in proactive mechanisms of locomotor stability with potentially greater medial-lateral stability on the sound limb side irrespective of prosthesis use, but heavier prostheses reduced the walking base of support. This bias may enhance fall risk on the impaired side if the prosthetic limb is used inappropriately to regain balance following a disturbance. Research is warranted to explore the consequences of this asymmetry on perturbation response.
上肢截肢者（ULL）跌倒的发生率很高，大多数跌倒发生在行走时。这个问题可能与手臂动力学的改变有关，手臂动力学在主动运动稳定机制中起着重要作用。本研究调查了 ULL 和假肢使用对上主动稳定机制的影响，特别是如果将假肢的质量和惯性与健全肢体相匹配，是否会提高运动稳定性。在水平行走时，收集了单侧 ULL 成年人的步态数据，同时：（1）不佩戴假肢，（2）佩戴惯用假肢，（3）佩戴与健全肢体质量和惯性匹配的模拟假肢。分析了肢体侧和条件对躯干旋转、手臂摆动、步宽、自由垂直力矩和稳定裕度的主要和交互效应。在所有条件下，健全肢体侧的手臂摆动、自由垂直力矩和稳定裕度分别比受损肢体侧大 2.27、1.13 和 1.20 倍。上肢截肢者在运动稳定的主动机制中表现出不对称性，无论是否使用假肢，健全肢体侧的横向稳定性都可能更大，但较重的假肢会减小步行支撑基础。如果假肢在受到干扰后恢复平衡时使用不当，这种偏差可能会增加受损侧的跌倒风险。有必要进行研究，以探讨这种不对称性对扰动反应的影响。
