Colobert Briac, Crétual Armel, Allard Paul, Delamarche Paul
Laboratoire de Physiologie et Biomécanique de l'Exercice Musculaire, UFR-APS CS 24 414, Rennes, France.
Clin Biomech (Bristol). 2006 May;21(4):427-34. doi: 10.1016/j.clinbiomech.2005.12.003. Epub 2006 Jan 27.
Using statistical characteristics of the centre of pressure displacement or of the ground reaction forces, it is difficult to have quantitative evaluation of the equilibrium strategy employed (ankle or hip). The purpose of this study is to validate a new force-plate based approach that allows to evaluate postural strategies employed through a method based on a double-inverted pendulum model.
This method allows to compute ankle and hip joint motion only from force plate data and relies on inverse kinematics with the centre of mass considered as the end effector. Furthermore, an index, depending on the covariance between hip and ankle angles, is proposed to quantify the strategy used. To validate the method and the strategy index, we compare the results of our computation to an optical stereophotogrammetry measurement of the angles considered as reference value.
The experiments demonstrate that our method provides acceptable results. The root mean square error between computed and measured hip and ankle angles stands between 4.5 x 10(-3)degrees for ankle angle in static condition and 1.1 x 10(-1) degrees for hip angle in hip forced condition.
The main interest of our method for clinicians is that it allows to retrieve the ankle and hip angles only using a simple and widespread device, the force-plate. Moreover, it proposes a new postural index that can be also be computed without videographic systems.
利用压力中心位移或地面反作用力的统计特征，很难对所采用的平衡策略（踝关节或髋关节）进行定量评估。本研究的目的是验证一种基于测力台的新方法，该方法能够通过基于双倒立摆模型的方法来评估所采用的姿势策略。
该方法仅根据测力台数据计算踝关节和髋关节的运动，并依赖于将质心视为末端执行器的逆运动学。此外，还提出了一个取决于髋关节和踝关节角度协方差的指标，以量化所使用的策略。为了验证该方法和策略指标，我们将计算结果与作为参考值的角度的光学立体摄影测量结果进行比较。
实验表明我们的方法提供了可接受的结果。计算得到的髋关节和踝关节角度与测量值之间的均方根误差，在静态条件下踝关节角度为4.5×10⁻³度，在髋关节受力条件下髋关节角度为1.1×10⁻¹度。
我们的方法对临床医生的主要好处在于，它仅使用一种简单且广泛使用的设备——测力台，就能获取踝关节和髋关节角度。此外，它还提出了一种新的姿势指标，该指标也可以在没有摄像系统的情况下进行计算。
