Functional flatfoot is a common foot disease which induces pain and functional decline. Insoles can be used for intervention and correction, especially customized insoles which are made according to different foot types. There have been few studies using 3D printing for customized insoles for functional flatfoot. Besides, compared to traditional method and subtractive manufacturing, the effect of 3D printing customized insoles is still controversial and depends on technology, materials and design.The purpose of present study is to compare the effects of 3D printing customized insoles using different thermoplastic materials on functional flatfoot patients' foot function and biomechanics. Twelve patients with functional flatfoot (foot function index> 6) aged 20-65 years old will be recruited in this study. Participants plan to wear three kinds of customized insoles fabricated by 3D printing with Nylon and TPU or computer numerical control machine with EVA. F-Scan system and questionnaires will be used to record foot biomechanics and pain after wearing insoles immediately, and foot condition after three weeks. Statistical analysis will be adopted for repeated-measures analysis of variance （ANOVA） for all outcome measures and post-hoc test will be used to test the difference between groups.
The aim of present study is to compare the effects of 3D printing customized insoles using different thermoplastic materials on functional flatfoot patients' foot function and biomechanics