In this study, phase plane analysis was used to describe the mechanisms involved in human intralimb dynamics during a multijoint coordinated task. Nonhandicapped, spastic, and athetoid cerebral palsied individuals were videotaped as they performed a stepping task. Kinematic data for the hip and knee joint angles were digitized, smoothed, differentiated, and plotted. Phase plane analysis of movement data reveals striking differences between nonhandicapped and cerebral palsied individuals. Whereas nonhandicapped individuals have trajectories in the phase plane that suggest a self-contained second-order dynamical system, cerebral palsied individuals have self-interesting loops in their phase planes. Based upon these patterns some dynamical distinctions are offered, and suggestions are made toward a possible model.
Anne Beuter and Alan Garfinkel
Emmie Hsu, Steve Bardfield, Bryant J. Cratty, and Alan Garfinkel
This pilot study was conducted to test the usefulness of angle-angle diagrams and phase plane plots obtained through high-speed cinematographical methods for making graded assessments of associated movements in children. Kinematic data at the shoulder, elbow, and ankle joints of normal and motorically awkward children (5-7 years old) were obtained from digitized films of normal and heel walking trials on a motor driven treadmill. A computer program was developed to smooth, calculate, differentiate, and plot data. Angle-angle diagrams depicting simultaneous joint angular displacements of (a) shoulder versus ankle and (b) elbow versus ankle revealed graded differences in decoupling of joint motion, limb excursions, and joint range-of-motion changes between the 5-year-old, 7-year-old awkward, and 7-year-old normal subject. Phase planes of the shoulder, elbow, and ankle joint were obtained by plotting joint angular displacement against joint angular velocity. Differences in size, shape, and looping behavior showed the quantity of change and whether the changes were gradual or sudden. This noninvasive methodology and eventual standardization of angle-angle diagrams and phase planes could prove to be useful in providing more precise diagnoses of associated movements and other subtle movement disorders.