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

Kuang-Wei Lin,Chen-Sheng Chen,Wen-Wen Yang,Chia-Jung Hu,Pi-Chang Sun,Li-Wei Chou,Shun-Hwa Wei

doi:10.1155/2019/4989534

Abstract

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.

Highlights

Foot orthoses (FOs) are commonly used as interventions for individuals with flexible flatfoot [1, 2]
The executed compressive tests revealed that the 45° and 90° build orientations engendered similar load and displacement behaviors in the FOs when the displacement was less than 5 mm (Figure 4)
The key findings of this study are that the use of 3D-printed FOs decreased the maximum ankle evertor and external rotator moments but increased the maximum ankle plantar flexor moment during walking

Summary

Introduction

Foot orthoses (FOs) are commonly used as interventions for individuals with flexible flatfoot [1, 2]. Wearing FOs might improve the pain scores [3] and alter the kinematics and kinetics of the rearfoot; for example, FOs reduce the peak rearfoot eversion [3, 4] and joint moment in the frontal plane [5]. A study indicated that the same shoe insert interventions produce substantially different effects for dissimilar individuals [6]. The actual prescription of orthotic devices is patient specific; this is because various levels of malalignments likely require different FO designs. According to the current manufacturing method, FOs can be either custom fabricated or prefabricated.

Methods

Results

Discussion

Conclusion