Motion of the center of gravity of the body in clinical evaluation of gait.

The motion of the center of gravity during walking was analyzed in five hemiplegic subjects and eleven subjects affected by unilateral hip arthritis. In the hemiplegic subjects and 6 subjects with hip arthritis the transfer between kinetic and potential energy (with a passive pendular motion) was found to be 9-95% greater during the step performed on the affected limb ("pathological" step); as a consequence, the muscular work done during this step was 7-81% of the work done during the step performed on the second limb ("normal" step). Qualitatively similar gait anomalies were recorded in all hemiplegic subjects with hypertonus of the paretic limb: these subjects had to lift the spastic limb as a whole during the normal step, with the consequence that the center of gravity was lifted 0.6-3 cm more than during the pathological step. In contrast, various motor patterns were found in patients with hip arthritis. During the pathological step the center of gravity reached a height 0.5-3 cm greater in 7 subjects, 1 cm smaller in one subject, and about the same height reached during the normal step in 3 subjects. This was consistent with the various motor deficits caused by hip arthritis.