Triceps surae shortening in children

BACKGROUND: The triceps surae is the main muscle that exerts propulsion power during walking and running. Its retraction changes the biomechanics of the foot, alters locomotion, and results in the secondary development of flatfoot deformity. Literature data on the clinical assessment of triceps surae retraction vary. AIM: To assess the threshold value of foot dorsiflexion in different clinical assessment methods of determining Achilles tendon shortening. MATERIALS AND METHODS: The study included the clinical assessment results of foot dorsiflexion in 167 patients (325 feet) with flatfeet aged 7–18 years. The foot dorsiflexion evaluation consisted of the assessment of isolated foot dorsiflexion and foot dorsiflexion with stabilization of the tarsal joints. To determine the involvement of the gastrosoleus complex in the pathological process, foot dorsiflexion was assessed with knee joint flexion and extension. The obtained data were subjected to correlation, regression, and Bland–Altman analyses. RESULTS: Strong correlations were found when foot dorsiflexion was assessed with the same knee joint position (assessment of isolated foot dorsiflexion and foot dorsiflexion with stabilized tarsal joints and knee joint flexion; the same tests with knee joint extension). Moderate correlations were noted when comparing foot dorsiflexion with knee joint extension and flexion. In the regression analysis, formulas were obtained according to which the threshold values of foot dorsiflexion were calculated in various variants during knee joint flexion and extension, indicating the retraction of the triceps surae: isolated foot dorsiflexion with knee joint extension 20°, isolated foot dorsiflexion with knee flexion 36°, and foot dorsiflexion with tarsal joint stabilization and knee extension 23°. CONCLUSIONS: Retraction of triceps surae in children with flatfeet equally involves the gastrocnemius and soleus. Differences in the magnitude of foot dorsiflexion with knee joint flexion and extension are the main factors in the retraction of the triceps surae to the gastrocnemius muscle.