Surgical lengthening is used to address both overactivity and shortening of the spastic agonist muscle in children with cerebral palsy. It has been presumed that the function of the antagonist muscle will improve when the spastic agonist muscle has been surgically lengthened. The purposes of the current study were to use quantitative gait analysis to determine the prevalence of the ankle dorsiflexor muscles (antagonist) dysfunction during the swing phase of the gait cycle and to analyze how this function is affected following surgical lengthening of the ankle plantar flexor muscles (agonist).Methods:
The study design was a retrospective, cohort series of fifty-three children with cerebral palsy who underwent gait analysis before and after surgical lengthening of the gastrocnemius-soleus muscle group. Data from the physical examination, gait study kinematics, and dynamic electromyography in swing phase were analyzed.Results:
The mean age at the time of the initial gait analysis was eight years and eleven months. Significant improvements were noted in ankle dorsiflexion passive range of motion (p < 0.001), ankle dorsiflexor selective control (p = 0.002), ankle dorsiflexor strength (p = 0.001), and peak and mean ankle dorsiflexion in swing phase (p < 0.001 for each) following ankle plantar flexor lengthening surgery. Active ankle dorsiflexor function in swing phase was present in 79% of the extremities prior to ankle plantar flexor surgery. Swing phase dorsiflexor function was present in 96% of the extremities following surgery, with ten extremities improving from absent to present.Conclusions:
The kinematic data support the clinical impression that ankle dorsiflexion during swing phase is improved following ankle plantar flexor lengthening surgery in children with cerebral palsy. In the majority of patients, this was a consequence of the correction of a fixed equinus contracture of the ankle plantar flexors that was constraining preexisting ankle dorsiflexor function. Weakness of all of the muscles is common, and surgical lengthening should only be considered for the correction of recalcitrant muscle contractures. Improved function of the antagonist muscle should be anticipated and optimized by appropriately focused strength training and other modalities during rehabilitation.Level of Evidence:
Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.