A novel design conception of foot orthoses promotes normal walking in patients with pronated feet.

backgroundFoot orthosis (FO) is one of the most important treatments for pressure relief and gait rehabilitation in the foot misalignment population. The previous design conception was primarily focused on arch support and pressure reduction, but recent studies also questioned their efficiency.

methodsThree bionic fish bone FOs based on the COP characteristics of healthy people were designed and manufactured. The orthoses were tested in 30 volunteers through a series of experiments including both static standing and dynamic gait, and evaluated through finite element (FE) simulations with a detailed ankle-foot model considering deep tissue deformation.

resultsIn the static standing experiments, the calcaneus eversion angle was corrected with average ratios of 56%, 43% and 37% through three FO interventions, while the navicular drop height was reduced by average ratios of 65%, 54% and 46%. In dynamic gait experiments, obvious corrections for the COP curves of the volunteers were noted when comparing the COP corridor of healthy people, while COP excursion index values also increased by average ratios of 34%, 32% and 21% through 3 FO interventions. By the way, the peak plantar pressure was spontaneously reduced with an average ratio from 3% to 10%. Dynamic gait analysis with FE models also demonstrated that the foot orthoses can significantly reduce strain levels in the deep plantar soft tissues of flat feet from 1.6% to 28.9%.

conclusionThe change of evaluation indexes indicated significant effects of the present design on the correction of abnormal foot functions. We also believe that the present design can be extended for injury prevention or rehabilitation of other foot function-related diseases, such as diabetes or foot ligament laxity.