Introduction of several common types of prosthetic feet

Introduction of several common types of prosthetic feet

Several commonly used prosthetic feet are classified as follows:

(1) SACH pin

SACH feet are fixed ankle soft heels. Its ankle and midfoot sections consist of an inner wood core covered with foam and shaped like a foot. Its heel is equipped with a soft plastic foam wedge, which is also called a soft heel. When the heel hits the ground, the soft heel deforms under pressure and then hits the bottom of the foot, similar to plantar flexion of the foot. As the prosthetic foot continues to roll forward, the movement of the forefoot portion of the foam shell approximates the dorsal extension of the toes. The movement of the prosthetic foot in the sagittal plane is achieved by the elastic material on the foot.

SACH feet are lighter in weight. It can also be used for calf prostheses to get better results. When used for thigh prostheses, it is only suitable for patients who walk on flat ground or patients in areas with relatively simple ground conditions. The flexible movement of the foot is limited to the heel and metatarsophalangeal joints, and it has no inversion and rotation functions. As the height of the amputation increases and the complexity of the terrain increases, the foot is less suitable. In addition, because it is relatively hard when hitting the ground, it also has an adverse effect on the stability of the knee joint.
(2) Energy storage pin

The energy storage foot was developed on a soft-heeled foot with a simple structure and light weight. It has been further improved in structure. Increased mobility of the foot in all directions. It stores energy during the support period and releases it during the kickback. The rate of energy release is related to the structure of the foot and the energy storage material used. This prosthetic foot is designed for sports such as running and jumping, and is suitable for patients with high mobility.

(3) Single shaft foot

A uniaxial foot has an articulation axis relative to the human ankle joint. The foot can do dorsiflexion and plantarflexion around this axis. The structure of the foot also determines that it can only move in the sagittal plane. The range of motion and damping of dorsiflexion and plantar flexion of the uniaxial foot can be adjusted by means of cushioning devices located in front of and behind the shaft. They also play a role in the stability of the knee joint. The disadvantage of this type of foot is that it is heavy, used for a long time or in poor conditions, and the joints are worn out.