Kinematic analysis of human walking gait using digital image processing.

A system using digital image processing techniques for kinematic analysis of human gait has been developed. The system is cheap, easy to use, automated and provides useful detailed quantitative information to the medical profession. Passive markers comprising black annuli on white card are placed on the anatomical landmarks of the subject. Digital images at the standard television rate of 25 per second are acquired of the subject walking past a white background. The images are obtained, stored and processed using standard commercially available hardware, i.e. video camera, video recorder, digital framestore and an IBM PC. Using a single-threshold grey level, all the images are thresholded to produce binary images. An automatic routine then uses a set of pattern recognition algorithms to locate accurately and consistently the markers in each image. The positions of the markers are analysed to determine to which anatomical landmark they correspond, and thus a stick diagram for each image is obtained. There is also a facility where the positions of the markers may be entered manually and errors corrected. The results may be presented in a variety of ways: stick diagram animation, sagittal displacement graphs, flexion diagrams and gait parameters.