Kinematic and kinetic evaluation of the ankle after intramuscular injection of botulinum toxin A in children with cerebral palsy.

Intramuscular botulinum toxin A (BTA) injection has a role in the conservative management of dynamic equinus deformity in children with cerebral palsy. The effect of BTA injection of the gastrocsoleus muscle during gait was evaluated. Eight children with hemiplegia (median age 4.4 years, range 2 to 8 years) were included in this retrospective study. Assessment included kinematic and kinetic gait analysis before and after (median 57.5 days) treatment. Postinjective kinematics showed significant improvement of ankle range of motion in the stance phase of gait. Ankle kinetics demonstrated a significant decrease of pathological power generation in midstance. The ankle power quotient (APQ) was also significantly improved. Ankle power in terminal stance was improved, although not to a significant level. These results provide evidence of normalization of energy production at the ankle, which is critical for normal gait. The effect of BTA is temporary and can be successfully repeated. This allows deferring the need for surgical intervention until the child is older and recurrence rate is lower.