Kappa Active Orthosis: a preliminary biomechanical study on the immediate effect of a novel orthotic intervention for pediatric flexible flat foot

BACKGROUND: Pediatric flexible flat foot is characterized by morphological dysmorphisms often associated with postural control and biomechanical gait alterations. Although there is no strong scientific evidence about the efficacy of foot orthoses, some authors suggest that these could modify gait biomechanics and improve postural control. Our hypothesis is that a novel type foot orthosis (Kappa active orthosis) is capable of influence gait biomechanics and postural control of children with flat feet. METHODS: Retrospective observational study on a cohort of 13 Viladot type II bilateral flexible flat-footed children (5-12 years old). 3D gait analysis in barefoot and with kappa orthosis was conducted. A 15 seconds standing test was performed to analyze center of pressure (CoP) trajectory of each foot in four conditions: with eyes opened (OA) and closed (OC) both in barefoot and with Kappa orthosis. RESULTS: All the components of GRF significantly differs during 0-7% of the gait cycle; other significant differences were found on antero-posterior and vertical components of GRF during midstance and push-off between the tested conditions. A weak correlation was found between Staheli Arch Index and the amount of mGRF variation. No significant differences were found analyzing CoP swing and velocity between conditions but an interesting trend on median values of medio-lateral oscillations was found. CONCLUSIONS: The double wedge hindfoot support of the Kappa orthosis seems to be effective in modifying GRF during first rocker. Analysis of CoP sway suggest that Kappa orthosis could play a role also as a proprioceptive and exteroceptive stimulus.