Institute of Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada.
KITE-Toronto Rehabilitation Institute, University Health Network, Toronto, Ontario, Canada.
J Neurophysiol. 2021 May 1;125(5):1681-1689. doi: 10.1152/jn.00302.2020. Epub 2021 Feb 24.
Individuals with motor incomplete spinal cord injuries (iSCI) often have impaired abilities to maintain upright balance. For able-bodied (AB) individuals, the ankle and hip joint accelerations are in antiphase to minimize the postural sway during quiet standing. Here we investigated how interjoint coordination between the ankle and hip joints was affected in individuals with iSCI, leading to their larger postural sway during quiet standing. Data from 16 individuals with iSCI, 14 age- and sex-matched AB individuals, and 13 young AB individuals were analyzed. The participants performed quiet standing during which kinematic and kinetic data were recorded. Postural sway was quantified using center-of-pressure velocity and center-of-mass acceleration. Individual ankle and hip joint kinematics were quantified, and the interjoint coordination was assessed using the cancellation index (CI), goal-equivalent variance (GEV), nongoal-equivalent variance (NGEV), and uncontrolled manifold (UCM) ratio. Individuals with iSCI displayed greater postural sway compared with AB individuals. The contribution of ankle angular acceleration toward one's sway was significantly greater for those with iSCI compared with AB groups. CI and the UCM ratios were not statistically different between the groups, while GEV and NGEV were significantly greater for the iSCI group compared with the AB groups. We demonstrated that individuals with iSCI show larger postural sway compared with the AB individuals during quiet standing, primarily due to larger ankle joint acceleration. We also demonstrated that the interjoint coordination between ankle and hip joint is not affected in individuals with iSCI, which is not successfully able to reduce the large COM acceleration. There are limited studies investigating the biomechanics of standing balance for individuals with motor incomplete spinal cord injury (iSCI). Through our study, we found that these individuals with iSCI demonstrated increased postural sway primarily due to increased ankle joint accelerations. In addition, the ankle-hip coordination was equivalent between able-bodied individuals and those with motor incomplete spinal cord injury, which was not able to reduce the large body acceleration.
患有运动不完全性脊髓损伤（iSCI）的个体通常存在维持直立平衡的能力受损的情况。对于健全人（AB），踝关节和髋关节的加速度是反相的，以最小化在安静站立时的姿势摆动。在这里，我们研究了 iSCI 个体的踝关节和髋关节之间的关节间协调如何受到影响，导致他们在安静站立时的姿势摆动更大。分析了 16 名 iSCI 患者、14 名年龄和性别匹配的 AB 个体和 13 名年轻 AB 个体的数据。参与者在安静站立时进行了测试，记录了运动学和动力学数据。使用中心压力速度和质心加速度来量化姿势摆动。量化个体踝关节和髋关节的运动学，并使用取消指数（CI）、目标等效方差（GEV）、非目标等效方差（NGEV）和非控制流形（UCM）比来评估关节间协调。与 AB 个体相比，iSCI 个体显示出更大的姿势摆动。与 AB 组相比，iSCI 患者的踝关节角加速度对其摆动的贡献明显更大。CI 和 UCM 比率在组间没有统计学差异，而 GEV 和 NGEV 在 iSCI 组明显大于 AB 组。我们表明，与 AB 个体相比，iSCI 个体在安静站立时表现出更大的姿势摆动，主要是由于踝关节加速度更大。我们还表明，iSCI 个体的踝关节和髋关节之间的关节间协调不受影响，无法成功减少大的 COM 加速度。目前关于运动不完全性脊髓损伤（iSCI）患者站立平衡生物力学的研究有限。通过我们的研究，我们发现这些 iSCI 患者的姿势摆动增加主要是由于踝关节加速度增加。此外，AB 个体和运动不完全性脊髓损伤个体之间的踝髋协调是等效的，无法减少大的身体加速度。
