Development of a foot orthosis modeling method to reduce model modification

[Purpose] According to the Orthotics (4th ed), positive models fabricated using the conventional impression foam-based modeling method require multiple modifications, including reductions at the waist girth, lateral aspect of the calcaneus, medial longitudinal arch, lateral longitudinal arch, and metatarsal arch as well as additions to account for soft tissue deformation around the dorsum of the foot and the calcaneus. Achieving accurate fabrication therefore requires considerable working time and technical proficiency. [Participants and Methods] In this study, we developed the arch support molding method (ASMM), which enables acquisition of a post-modification model by having the participants step on a dedicated arch support during modeling, and evaluated the usefulness of this method. Both feet of 10 healthy participants (5 men and 5 women) were modeled using both the ASMM and the conventional method, and the time required for each procedure and the resulting shapes were compared. [Results] The results showed that ASMM required less working time compared with the conventional method, and the obtained shapes were closer to those of the post-modified positive models. [Conclusion] These findings indicate the high utility of ASMM.