Spasticity and contractures are a common problem in children with cerebral palsy (CP), yet the exact changes in muscle-tendon architecture associated with spasticity and contracture remain unknown. This study used ultrasound to image the medial gastrocnemius muscle-tendon unit in able-bodied children, children with CP who have spasticity without contracture, and children with CP who have developed contracture.

Normalized external tendon length was longer and normalized muscle belly length was shorter in subjects with CP than control subjects, with no significant difference between the two CP groups. Pennation angles were not significantly different between the three groups at ankle joint angles expressed relative to resting. Normalized fascicle lengths relative to resting ankle angle were shorter in the spasticity group than in the control group. Fascicle lengths were not significantly different between the control and contracture groups and between the two CP groups.