Influence of a novel elastic foot orthosis in foot motion during locomotion in adults with mild flatfoot

Background: Collapse of the foot arch is a one of the risk factors in medial tibial stress syndrome. Custom-made foot orthoses are used to reduce the collapse of foot arch, but the orthoses are designed for a specific shoe and cannot be used in other shoes. We developed an elastic foot orthosis that is highly fitted on the foot using thin films, is lightweight, and can be used with any shoe or without shoes. The purpose of this study was to investigate foot kinematics with our elastic foot orthosis during walking and running.

Methods: We recruited 30 participants with asymptomatic flatfoot for this study. Foot kinematic data were recorded for treadmill walking, treadmill running, and over-ground walking. Foot kinematics were recorded in three conditions, barefoot (BF), with the elastic foot orthosis (EFO), and with sham foot orthosis (SFO), and foot strain was measured using a stretch strain sensor. The difference in foot strain from initial contact to maximum strain during gait was calculated as loading arch strain, which was reflected as forefoot eversion excursion. A one-way analysis of variance with Bonferroni test was performed to compare the loading arch strain among the three conditions.

Results: In all tasks, loading arch strain with the EFO was significantly less than that in the BF and SFO conditions. Loading arch strain with the SFO was significantly more than that of BF in the treadmill gait condition.

Conclusion: Our results indicate that the EFO decreased foot strain during locomotion compared to without the EFO and is capable of supporting the foot arch during locomotion.