A prosthetic foot restores mobility to people with lower-limb amputation. People who do not walk may only require a cosmetic foot, which is light weight and non-functional as a foot. Selecting the proper functional foot depends on several factors. The two most important are activity level of the user and stability required at the foot.
A Solid Ankle Cushioned Heel (SACH) foot is a functional non-articulating foot that contains an inner keel to provide cushioning and absorb energy during walking. It has limited movement at the ankle joint, increasing its stability at this location. However, its lack of movement can make the overall leg less stable because movement must be accommodated in other joints. SACH are low cost and offer limited performance.
The articulated single-axis foot has a hinge joint that allows the forefoot to move up and down about the ankle, much like the natural foot. The multi-axis foot also enables the foot to move side to side in addition to up and down. These added degrees of freedom can enable the foot to lie flat on irregular surfaces enhancing the connection between the foot and the ground. This can lead to increased lower limb stability over uneven ground, but it must be balanced with the instability associated with the increased movement at the joint.
Modern high-tech feet made from light-weight carbon fiber, such as the dynamic-response foot, absorb and release energy during walking, producing a more typical range of motion and gait. These may be used by more active people and athletes. They may be worn directly on the walking or running surface or inserted into a foot cover to provide the appearance of a natural foot.
Innovations in artificial foot technology includes the use of microprocessor-controlled sensors to more closely mimic natural foot movement than other previous versions. Lower-limb amputations are prevalent, and people who use prosthetic feet have expressed a need for better functioning designs to improve their participation in daily activities.
