Background: According to traditional teaching, the posterior
tibialis is the main cause of varus foot deformity in patients with cerebral
palsy. However, the relative frequency of anterior and posterior tibialis
dysfunction has only been reported with use of dynamic electromyography in
relatively small series of patients, with contrasting results. The purpose of
the current study was to determine the relative prevalence of posterior and
anterior tibialis dysfunction with use of gait analysis in a large group of
patients with cerebral palsy and varus foot deformity.
Methods: The muscular contributors to varus foot deformity in
seventy-eight patients (eighty-eight feet) who had cerebral palsy were
evaluated with use of computerized motion analysis and dynamic
electromyography. Data also were examined to identify any relationships
between the timing of varus during gait and the contributing muscle.
Results: The muscular contributor to varus deformity was the
anterior tibialis in thirty feet, the posterior tibialis in twenty-nine feet,
both the anterior tibialis and the posterior tibialis in twenty-seven feet,
and another contributor in two feet. Seventy feet had varus deformity during
both stance phase and swing phase. Of these seventy feet, twenty-five
exhibited dysfunction of the anterior tibialis, twenty exhibited dysfunction
of the posterior tibialis, and twenty-three exhibited dysfunction of both
muscles. Therefore, the timing of varus was not predictive of the contributing
muscle or muscles.
Conclusions: The current study demonstrated a higher prevalence of
anterior tibialis dysfunction, both alone and in combination with posterior
tibialis dysfunction, as a contributor to pes varus in patients with pes varus
and cerebral palsy than had been reported previously. Dynamic electromyography
provides clinically useful information for the assessment of such
Clinical Relevance: Definitive information outlining the muscular
contributors to pes varus is needed in order to allow more effective surgical
correction of such deformities and to improve surgical outcomes.