There are two basic type of prosthetic feet; non-articulating (non-movable feet / rigid) and articulating feet (movable feet).
Examples of non-movable feet are SACH (Single Axis Cushion Heel) foot and elastic keel foot.
|Elastic keel feet.|
Basically elastic keel feet is just the same to SACH foot. The keel is more elastic in compare to the wooden keel of SACH foot.
The SACH foot is the simpler of the two. It is rigid and cannot bend. It has a rubber heel wedge that compresses under the user’s weight, allowing a little ankle movement early in the stance phase of walking (at the beginning of a step). It provides stability, but little lateral movement, in mid-stance (when walking). The SACH foot comes in several heel heights so it can be worn with different types of shoes. Elastic keel feet are a little more flexible than SACH feet. They allow the front part of the foot to adjust to varied walking conditions but stay stiff and stable while standing or walking.
The second type of prosthetic feet is articulated foot. There are three types of articulated feet: single-axis, multi-axis and dynamic-response feet. Both allow motion in one or more planes, much like the movement of a human foot.
· Have an ankle joint that allows the foot to move up and down, which adds knee stability.
· Are often used by people with higher levels of amputation (from the knee to the hip).
· Reduce the effort needed to control a prosthesis and keep the knee from buckling.
· Add weight to the prosthesis, need periodic repair and cost a little more than most basic feet.
· Are often used by people who need stability.
· Are similar to single-axis feet in terms of weight, need for repair, and cost.
· Move up and down as well as side to side to conform to uneven surfaces better than single-axis feet.
· Have ankle motion, which absorbs some of the stress of walking, protecting a person’s skin and reducing wear and tear on the prosthesis.
· Are often used by hikers, golfers, dancers and others who need a lot of foot movement.
· Store and release energy during the walking cycle.
· Give a sense of push-off, a more normal range of motion and balanced gait.
· May have a split-toe design to add stability.
· May lessen the impact on the heel of the person’s other foot.
· Are so comfortable and responsive that amputees might increase their level of activity.
· Are responsive and good for active amputees who vary their walking speed, change direction quickly, or walk long distances.
As technology in Prosthetics and Orthotics field is enlarge in mass, there are much more high technology of prosthetic foot can be invent in future.