Effect of foot orthoses on the medial longitudinal arch in children with flexible flatfoot deformity: A three-dimensional moment analysis.

Foot orthoses are often used to correct altered gait patterns. The purpose of this study was to investigate how foot orthoses can modify the magnitude of three dimensional moments of ankle, knee, and hip joints during a stride of gait in children with flexible flat feet. Bilateral gait data were collected from fourteen male children (age 10.2±1.4 years) suffering from flat feet syndrome. In order to obtain the kinematics data, a Vicon system with six cameras (100Hz) was used and two Kistler force plates (1000Hz) to record the kinetics data under each leg. Arc support foot orthoses were used as an intervention. Paired-sample T-test was used for within-group comparisons (α=0.05). The results of data analysis showed that foot orthoses can decrease the ankle evertor moment, knee and hip abductor moments and hip flexor moment in dominant lower limb. In non-dominant lower limb, using the orthoses can decrease evertor and internal rotator moments at the ankle, flexor and internal rotator moments at the knee and extensor moment at the hip, while it can increase dorsiflexor moment at the ankle. The findings imply that effects of orthoses on three dimensional moments differ in dominant and non-dominant lower limbs. Furthermore, results demonstrated that dominant and non-dominant lower limbs would also show different responses to the same intervention.