Most existing Orthotic components can be incorporated into composite Orthoses. The function of some orthotic components cannot be bettered by composites.
Metal for instance is a much better material than composites when in compression or friction. This makes metal a better material for Orthotic joints and fastening points such as straps (threads).
Effective incorporation of these components is the major factor. Simply screwing or riveting metal components is not effective. Weak points will be created and increased weight with decreased strength will be the result. Metal can be incorporated into the composite structure itself. If done with accuracy it can increase the mechanical properties of the composite material.
Plastics will not bond with composite resins. Plastic components need to be attached with fastenings.