Neckel Nathan, Pelliccio Marlena, Nichols Diane, Hidler Joseph
Center for Applied Biomechanics and Rehabilitation Research, National Rehabilitation Hospital, 102 Irving Street, NW, Washington, DC 20010, USA.
J Neuroeng Rehabil. 2006 Jul 20;3:17. doi: 10.1186/1743-0003-3-17.
The presence of abnormal muscle activation patterns is a well documented factor limiting the motor rehabilitation of patients following stroke. These abnormal muscle activation patterns, or synergies, have previously been quantified in the upper limbs. Presented here are the lower limb joint torque patterns measured in a standing position of sixteen chronic hemiparetic stroke subjects and sixteen age matched controls used to examine differences in strength and coordination between the two groups.
With the trunk stabilized, stroke subjects stood on their unaffected leg while their affected foot was attached to a 6-degree of freedom load cell (JR3, Woodland CA) which recorded forces and torques. The subjects were asked to generate a maximum torque about a given joint (hip abduction/adduction; hip, knee, and ankle flexion/extension) and provided feedback of the torque they generated for that primary joint axis. In parallel, EMG data from eight muscle groups were recorded, and secondary torques generated about the adjacent joints were calculated. Differences in mean primary torque, secondary torque, and EMG data were compared using a single factor ANOVA.
The stroke group was significantly weaker in six of the eight directions tested. Analysis of the secondary torques showed that the control and stroke subjects used similar strategies to generate maximum torques during seven of the eight joint movements tested. The only time a different strategy was used was during maximal hip abduction exertions where stroke subjects tended to flex instead of extend their hip, which was consistent with the classically defined "flexion synergy." The EMG data of the stroke group was different than the control group in that there was a strong presence of co-contraction of antagonistic muscle groups, especially during ankle flexion and ankle and knee extension.
The results of this study indicate that in a standing position stroke subjects are significantly weaker in their affected leg when compared to age-matched controls, yet showed little evidence of the classic lower-limb abnormal synergy patterns previously reported. The findings here suggest that the primary contributor to isometric lower limb motor deficits in chronic stroke subjects is weakness.
异常肌肉激活模式的存在是限制中风患者运动康复的一个有充分记录的因素。这些异常肌肉激活模式，即协同作用，此前已在上肢进行了量化。本文展示的是在16名慢性偏瘫中风患者和16名年龄匹配的对照组受试者站立位测量的下肢关节扭矩模式，用于检查两组之间力量和协调性的差异。
在躯干稳定的情况下，中风患者用健侧腿站立，患侧脚连接到一个六自由度测力传感器（JR3，加利福尼亚州伍德兰），该传感器记录力和扭矩。受试者被要求围绕给定关节（髋关节外展/内收；髋、膝和踝关节屈伸）产生最大扭矩，并提供他们为该主要关节轴产生的扭矩反馈。同时，记录来自八个肌肉群的肌电图数据，并计算围绕相邻关节产生的次要扭矩。使用单因素方差分析比较平均主要扭矩、次要扭矩和肌电图数据的差异。
在测试的八个方向中的六个方向上，中风组明显较弱。对次要扭矩的分析表明，对照组和中风组在测试的八个关节运动中的七个运动中使用了相似的策略来产生最大扭矩。唯一使用不同策略的情况是在最大髋关节外展用力时，中风患者倾向于屈曲而不是伸展髋关节，这与经典定义的“屈曲协同作用”一致。中风组的肌电图数据与对照组不同，在于拮抗肌群存在强烈的共同收缩，尤其是在踝关节屈曲以及踝关节和膝关节伸展时。
本研究结果表明，与年龄匹配的对照组相比，中风患者在站立位时患侧腿明显较弱，但几乎没有先前报道的经典下肢异常协同模式的证据。此处的研究结果表明，慢性中风患者等长下肢运动功能障碍的主要原因是无力。
