Biomechanical Evaluation and Strength Test of 3D-Printed Foot Orthoses

Abstract EN

Foot orthoses (FOs) are commonly used as interventions for individuals with flatfoot.

Advances in technologies such as three-dimensional (3D) scanning and 3D printing have facilitated the fabrication of custom FOs.

However, few studies have been conducted on the mechanical properties and biomechanical effects of 3D-printed FOs.

The purposes of this study were to evaluate the mechanical properties of 3D-printed FOs and determine their biomechanical effects in individuals with flexible flatfoot.

During mechanical testing, a total of 18 FO samples with three orientations (0°, 45°, and 90°) were fabricated and tested.

The maximum compressive load and stiffness were calculated.

During a motion capture experiment, 12 individuals with flatfoot were enrolled, and the 3D-printed FOs were used as interventions.

Kinematic and kinetic data were collected during walking by using an optical motion capture system.

A one-way analysis of variance was performed to compare the mechanical parameters among the three build orientations.

A paired t-test was conducted to compare the biomechanical variables under two conditions: walking in standard shoes (Shoe) and walking in shoes embedded with FOs (Shoe+FO).

The results indicated that the 45° build orientation produced the strongest FOs.

In addition, the maximum ankle evertor and external rotator moments under the Shoe+FO condition were significantly reduced by 35% and 16%, respectively, but the maximum ankle plantar flexor moments increased by 3%, compared with the Shoe condition.

No significant difference in ground reaction force was observed between the two conditions.

This study demonstrated that 3D-printed FOs could alter the ankle joint moments during gait.