Center for Human Movement Sciences, University Medical Centre Groningen, University of Groningen, A Deusinglaan 1, Sector F, 9713 AV Groningen, The Netherlands.
Med Eng Phys. 2010 Nov;32(9):1009-14. doi: 10.1016/j.medengphy.2010.07.001. Epub 2010 Aug 3.
Variability and stability of walking of eight transfemoral amputees and eight healthy controls was studied under four conditions: walking inside on a smooth terrain, walking while performing a dual-task and walking outside on (ir)regular surfaces. Trunk accelerations were recorded with a tri-axial accelerometer. Walking speed, mean and coefficient of variation of stride times (ST) and the root mean squares (RMS) of trunk accelerations was calculated. Gait variability and stability were quantified using measures derived from the theory of stochastic dynamics. Regularity was indexed using the sample entropy (SEn) and the scaling exponent α derived form Detrended Fluctuations Analysis. Local stability (LSE) quantified gait stability. Walking speed was lower, but ST variability was not different for amputees than controls. RMS of medio-lateral accelerations was higher for amputees; SEn was higher, implying less predictable accelerations, and LSE higher, indicating decreased stability. The largest condition effect was present for walking outside: trunk RMS increased and LSE decreased. Differences in walking between amputees and healthy controls and their responses to perturbations revealed themselves in the magnitude, variability and stability measures of trunk accelerations. These results imply that quantifying the dynamical structure of trunk accelerations can differentiate between groups with different walking abilities and between conditions of increasing difficulty and may therefore provide a useful diagnostic tool.
研究了 8 名股骨截肢者和 8 名健康对照者在 4 种条件下的行走变异性和稳定性：在光滑的室内地面行走、执行双重任务行走和在（不）规则表面的室外行走。使用三轴加速度计记录躯干加速度。计算行走速度、步时均值和变异系数 (ST) 以及躯干加速度的均方根 (RMS)。使用随机动力学理论得出的指标来量化步态变异性和稳定性。使用样本熵 (SEn) 和源自去趋势波动分析的标度指数 α 来评估规律性。局部稳定性 (LSE) 量化了步态稳定性。与对照组相比，截肢者的行走速度较低，但 ST 变异性没有差异。中间-外侧加速度的 RMS 更高；SEn 更高，意味着加速度更不可预测，LSE 更高，表明稳定性降低。室外行走的条件影响最大：躯干 RMS 增加，LSE 降低。与健康对照组相比，截肢者的行走差异及其对干扰的反应表现在躯干加速度的幅度、变异性和稳定性指标上。这些结果表明，定量分析躯干加速度的动力学结构可以区分不同行走能力的群体以及难度不断增加的条件，因此可能提供一种有用的诊断工具。
