A technique for the display of joint movement deviations.

Abstract

Detection of deviations in lower-limb joint movements derived during locomotion testing may be enhanced by displaying as a function of the gait cycle the algebraic difference between actual performance and a synthetic waveform. A synthetic waveform for a joint movement may be generated by applying Fourier series coefficients derived from a statistical treatment of test data characterizing the performance of normal healthy individuals walking at various velocities. Application of waveform specifics related to velocity yields a synthetic pattern serving as the criterion at the specific velocity demonstrated by a patient. The deviations, when plotted for the gait cycle, show the manner in which the actual waveform differs from the synthetic. At any increment of the gait cycle, the magnitude of the deviation and whether it is positive or negative can be determined. A positive deviation means that an expected angular position was exceeded, while a negative deviation means that an expected angular position was not reached. Individual signatures may be identified by the shape of the deviation pattern. Detection of the presence of oscillatory components in joint movements may be enhanced. Deviation patterns, developed from joint movements monitored bilaterally, often reveal compensatory activity with regard to the relative performances of the ipsilateral and contralateral limbs. Deviation amplitudes exceeding statistically determined boundaries for the synthetic waveform (e.g., two standard deviations) at specific zones of the support or wing phases facilitate identification of dysfunction. This paper describes the technique for deriving the deviation pattern, and touches upon its potential utility in evaluating locomotory performance of patients.