Short-term Effects of Botulinum Toxin A and Serial Casting on Triceps Surae Muscle Length and Equinus Gait in Children with Cerebral Palsy

Aims: The aim of the study was to perform a comprehensive analysis of the short-term effects of a standardized high dose of BTX-A and serial casting on spastic equinus in children with cerebral palsy. A second goal was to evaluate this short-term effect on muscle lengths of the triceps surae. Materials and methodology: Prospective study on 10 children (17 limbs) with spastic cerebral palsy and equinus gait pattern. Three-dimensional kinematic and kinetic gait analysis with musculo-skeletal modelling was used to evaluate pre- and 10 weeks post-treatment results. The paired Student's T-test was used for data analysis. Results: Walking velocity and stride length did not change after BTX-A application. The maximal ankle angle at the end of single support increased (p = 0.045) which led to a change of the ankle angle slope quotient towards normal positive values (p = 0.001). Abnormal ankle power generation in the first part of single stance changed towards normal (p = 0.012). Notably, the ankle plantar-flexor power was not reduced 10 weeks after BTX-A injection (p = 0.486). No lengthening of the triceps surae muscles compared to the baseline assessment was found. Conclusions: Beneficial functional changes in ankle kinematics and kinetics after the application of BTX-A when combined with serial casting were demonstrated. The results of our study underline the possible differences in effect of BTX-A on intrafusal and extrafusal muscle fibres.