Muscle architecture in children with cerebral palsy and ankle contractures: an investigation using diffusion tensor imaging.

Abstract

Children with cerebral palsy frequently have ankle contractures which may be caused by changes in architecture of calf muscles. Here, we compared the architecture of medial gastrocnemius muscles in children with unilateral cerebral palsy and typically developing children using novel imaging techniques. Muscle volumes, fascicle lengths, pennation angles and physiological cross-sectional areas were measured from diffusion tensor images and mDixon scans obtained from 20 ambulant children with unilateral spastic cerebral palsy who had ankle contractures (age 11 ± 3 years; mean ± standard deviation) and 20 typically developing children (11 ± 4 years). In children with cerebral palsy, the more-affected side had, on average, 13° less dorsiflexion range and the medial gastrocnemius muscle had 4.9 mm shorter fascicles, 50 cm³ smaller volume and 9.5 cm² smaller physiological cross-sectional area than the less-affected side. Compared to typically developing children, the more-affected side had 10° less dorsiflexion range and the medial gastrocnemius muscle had 4.2 mm shorter fascicles, 51 cm³ smaller volume and 10 cm² smaller physiological cross-sectional area. We did not detect differences between the less-affected and typically developing legs. Three-dimensional measurement of whole medial gastrocnemius muscles confirmed that the architecture of muscles on the more-affected side of children with cerebral palsy differs from the less-affected side and from muscles of typically developing children. Reductions in fascicle length, muscle volume and physiological cross-sectional area may contribute to muscle contracture.