A measure of motor control at the knee in cerebral palsy

This investigation developed a measure of motor control for the knee extens ors in adults with cerebral palsy (CP). Four adults with CP and 4 able-bodi ed (AB) adults participated. A KinCom dynamometer rotated the knee from app roximately 90 degrees of knee flexion to 10 degrees /s less than the partic ipant's maximum knee extension at a speed of 10 degrees /s, while the parti cipant attempted to match a 44.5-N "target" force. The average, standard de viation, and median frequency of the force-time data were used to describe the test results. The individual force values for the AB group were near th e target force and clustered together. The values for the CP group were als o near the target force, but displayed greater variation. The average stand ard deviation for the CP group was more than three times lar er than that o f the AB group. The average median frequency for the CP group was less than that of the AB group. Results pointed to differing strategies for each gro up as they attempted to match the target force. The AB group attempted to m atch the target force with frequent small-magnitude force changes, while th e CP group attempted to match the target force with fewer oscillations of g reater magnitude. The methods employed in the present investigation are ini tial attempts to quantify one aspect of motor control, a visually guided tr acking task.