Article

OBJECTIVE: To quantify dynamic spasticity, i.e. the coupling between
muscle-tendon stretch velocity and muscle activity during gait, of the
gastrocnemius and soleus muscles in children with spastic cerebral palsy. DESIGN:
Prospective, cross-sectional study. SUBJECTS: Seventeen ambulatory children with
cerebral palsy with spastic calf muscles, and 11 matched typically developing
children. METHODS: The children walked at 3 different speeds. Three-dimensional
kinematic and electromyographic data were collected. Muscle-tendon velocities of
the gastrocnemius medialis and soleus were calculated using musculoskeletal
modelling. RESULTS: In typically developing children, muscles were stretched fast
in swing without subsequent muscle activity, while spastic muscles were stretched
more slowly for the same walking speed, followed by an increase in muscle
activity. The mean ratio between peak activity and peak stretch velocity in swing
was approximately 4 times higher in spastic muscles, and increased with walking
speed. In stance, the stretch of muscles in typically developing children was
followed by an increase in muscle activity. Spastic muscles were stretched fast
in loading response, but since muscle activity was already built up in swing, no
clear dynamic spasticity effect was present. CONCLUSION: Spastic calf muscles
showed increased coupling between muscle-tendon stretch velocity and muscle
activity, especially during the swing phase of gait.

Langue : ANGLAIS