Design of a segmented custom ankle foot orthosis with custom-made metal strut and 3D-printed footplate and calf shell.

Abstract

3D-printing is a potential manufacturing process for optimizing the design and manufacture of ankle foot orthosis (AFOs). The feasibility of an AFO with interchangeable strut that is suitable for 3D-printing is created and evaluated. A segmented AFO with 3D-printed custom footplate and calf shell connected by a custom-made strut is studied. The duration of a healthy subject wearing the 3D-printed segmented AFO in daily activities is used to evaluate the feasibility and durability to integrate 3D-printed AFOs into orthotics practice. The 3D-scanning of a patient's leg is first conducted. The scanned 3D surface is modified by creating the clearance around bony prominences and trimlines for the footplate and calf shell. The footplate has a custom-shaped inside to match with the foot and a standard shape outside at the top to match and connect with the strut. For the calf shell, the inside shape is custom fit with the shank and the outside shape is standard to connect with the strut. Material extrusion is the 3D-printing process selected. Tree-like support structures are used to avoid the use of soluble support material and to eliminate the risk of residual chemical solvent in the orthosis. The segmented AFO with material extrusion footplate and calf shell was tested in a healthy subject with an active lifestyle, offering comfort, and stability for over 4 months without breakage. This segmented AFO is durable, requires short 3D-printing time, and enables the quick adjustment of bending stiffness via an interchangeable strut design.