Almonroeder Thomas G, Benson Lauren C, O'Connor Kristian M
Musculoskeletal Injury Biomechanics Laboratory, Department of Kinesiology, University of Wisconsin - Milwaukee, Milwaukee, WI.
J Appl Biomech. 2015 Jun;31(3):149-58. doi: 10.1123/jab.2014-0100. Epub 2014 Dec 23.
The mechanism of action of a foot orthotic is poorly understood. The purpose of this study was to use principal components analysis (PCA) to analyze the effects of a prefabricated foot orthotic on frontal plane knee and ankle mechanics during running. Thirty-one healthy subjects performed running trials with and without a foot orthotic and PCA was performed on the knee and ankle joint angles and moments to identify the dominant modes of variation. MANOVAs were conducted on the retained principal components of each waveform and dependent t tests (P < .05) were performed in the case of significance. Mechanics of the ankle were not affected by the foot orthotic. However, mechanics of the knee were significantly altered as subjects demonstrated an increase in the magnitude of the knee abduction moment waveform in an orthotic condition. Subjects also demonstrated a significant shift in the timing of the knee abduction moment waveform toward later in the stance phase in the orthotic condition. These orthotic effects were not related to subject's foot mobility, measured using the navicular drop test. The mechanism of action of a foot orthotic may be related to their effect on the timing of frontal plane knee loading.
足部矫形器的作用机制尚不清楚。本研究的目的是使用主成分分析（PCA）来分析预制足部矫形器对跑步过程中额面膝关节和踝关节力学的影响。31名健康受试者在佩戴和不佩戴足部矫形器的情况下进行跑步试验，并对膝关节和踝关节的角度及力矩进行PCA，以确定主要的变化模式。对每个波形保留的主成分进行多变量方差分析（MANOVA），在有显著性差异的情况下进行相关的t检验（P < 0.05）。足部矫形器未影响踝关节力学。然而，膝关节力学有显著改变，因为受试者在佩戴矫形器的情况下，膝关节外展力矩波形的幅度增加。受试者在佩戴矫形器的情况下，膝关节外展力矩波形的时间也显著向后移至站立相后期。这些矫形效果与使用舟骨下降试验测量的受试者足部活动度无关。足部矫形器的作用机制可能与其对额面膝关节负荷时间的影响有关。
