Impact of forefoot varus on standing and gait kinematics in children

Abstract

ObjectivesTo assess the compensations of proximal motion for forefoot varus (FV) by analysing the lower limb kinematics in standing and walking. MethodsA population of children (n = 375) underwent a goniometric evaluation of forefoot and hindfoot frontal-plane alignment (neutral/varus/valgus) drawn from a randomly selected primary school of Saragossa (Spain). Two groups were extracted: 1) forefoot varus group (FVG) (n = 30 FV children); 2) control group (CG) (n = 21 forefoot neutral children). The Oxford Foot Model and a conventional lower limb model were used to obtain kinematics while standing and walking. The Oxford Foot Model is a specific biomechanical model developed for the analysis of three-dimensional mobility of the ankle, hindfoot and forefoot in children. It is specifically adapted for paediatric use and offers normative data. Data acquisition was performed using a six-camera motion capture system. Kinematic variables were compared between both groups. Correlations between forefoot and hindfoot inversion/eversion with the rest of the kinematic variables in the FVG were carried out. ResultsFV children presented larger hindfoot eversion with flattening of medial longitudinal arch and larger hindfoot, knee and hip flexion, while standing and walking. Moreover, they walked with a higher anterior pelvis tilt and hip external rotation, and with smaller stride time and length and higher cadence. There was high correlation between forefoot inversion and hindfoot eversion during standing and some correlation between both forefoot inversion and hindfoot eversion and the rest of variables analysed during gait. ConclusionsThe results support the existence of a compensatory pronation of the subtalar joint. This is thought to occur during weight-bearing in order to achieve full contact of all metatarsal heads with the ground, and is probably responsible of an altered kinematic chain in the lower limb in standing and walking. FV correction might help to prevent this potentially harmful hindfoot compensation and the subsequent altered lower extremity kinematic chain.