Legendre polynomial coefficients in the analysis of the horizontal and lateral component of the force plate measurements for an osteoarthritic gait.

The assessment of force plate measurement obtained from subjects with a pathological gait, normally carried out by visual examination of the force-time data, can be augmented by consideration of Legendre polynomial coefficients. The first seven coefficients are evaluated and presented for the horizontal (forwards) and lateral (sideways) components of the force-time curves. It is shown that for an accurate assessment of specific osteoarthritic abnormalities it is necessary to consider the horizontal and lateral component data in addition to that previously presented for the vertical component. Relevance The Legendre analysis identifies the major gait factors from the shape of the curves and gives a reliable method of reducing the dynamic data to a simple set of numerical values by formalizing the classic approach of visual examination of the force-time curves. The method is particularly suitable for assessing the clinical gait condition in respect of heel-strike, toe-off, and stability.