Significance of the confusion test in cerebral palsy.

The confusion test examines ankle dorsiflexion in patients with cerebral palsy. Orthopedists have related this test to swing-phase activity of the tibialis anterior, and have used it as a prerequisite for tendon transfer. To determine the validity of this assumption, ankle dorsiflexion was tested in 47 normal children. Forty-seven percent had a positive, unresisted confusion test, and 97% had a positive, resisted confusion test. Twenty-three patients with cerebral palsy who had a positive confusion test underwent gait analysis. Tibialis anterior electromyographs showed wide variability. Sagittal-plane ankle-movement curves revealed five patterns. Thirty-three percent of the patients showed abnormal swing-phase dorsiflexion, and 61% had abnormal swing-phase plantar-flexion. We conclude that the confusion test evaluates a normal, patterned response, and is positive in most children with cerebral palsy. Although a positive confusion test shows that active ankle dorsiflexion is possible, it is not predictive of swing-phase ankle kinematics.