A good prosthetic foot needs to be strong and lightweight in order to carry the user’s weight and torque. It must also fit in a prosthetic foot shell, which is worn for cosmetic purposes and typically fits well inside a shoe. A common design for prosthetic feet is the SACH (solid-ankle-cushioned-heel) which is still quite popular because of its stability and function, especially for individuals with lower activity levels. The SACH foot has a rigid inner structure (usually made from wood or plastic) surrounded by a foam cosmetic shell.
Today’s more sophisticated feet are secured inside a cosmetic shell with many functions. Most people don’t see their prosthetic foot without it. They wear it for cosmetic purposes, but also to make sure that the prosthesis fills up all the space in the shoe.