The prosthetic socket is the interface part of the human-mechanical system that can comfortably house the stump and effectively transfer the force to the distal part of the prosthesis. The prosthetic socket of thigh prosthesis mainly includes conventional insertion prosthetic socket, quadrilateral full contact prosthetic socket, ISNY prosthetic socket, CAT-CAM prosthetic socket and so on.

 Conventional insert prosthetic socket

Traditional insertion prosthetic socket: The end is open. The aluminum leg in traditional prosthesis, the subepithelial aluminum thigh still uses this socket, often does not ensure the ischial bearing; To reduce the compression of the pubic symphysis the common method is adding rubber ring, but it still often causes the skin injury.

 Total contact quadrilateral socket

Total contact quadrilateral socket often referred to as the sorption of suction socket. This is a large internal and external diameter, anteroposterior diameter (ML diameter is larger than AP diameter) socket. Due to the small anterior and posterior diameter, appropriate pressure on the anterior wall equivalent to the femoral triangle can ensure that the ischial tuberosity falls on the seat of the superior margin of the posterior wall. There are four depressions in the socket that do not cause excessive compression of the adductor longus origin, rectus femoris, gluteus maximus, and hamstrings and limit muscle contraction. This kind of socket is in full contact with the stump, which not only shares the load bearing of the ischial bone but also plays a good role of suspension. It is a widely used socket at present.

                                                      Cross section of stump below the ischial tuberosity     Design of the socket below the ischial tuberosity

ISNY socket

Icelandic swedish – Newyork Socket is a quadrilateral full-contact socket with two layers inside and outside. The inner socket is made of transparent soft polyethylene and the outer socket is a load-bearing frame made of carbon fiber composite material. Because the inner socket is soft, it is comfortable to wear and does not interfere with some muscle movements.

The CAT - CAM socket

The CAT - CAM socket (contoured abducted trochanter – controlled alignment method socket). The disadvantages of the quadrilateral receptive cavity were discovered in the 1970s:

(1) When bearing weight, the abduction force of stump makes the sitting position move outward.

(2) When the hip is in flexion position, the ischium cannot bear weight when the foot follows the ground. For this reason, J. Abolich proposed a socket with a small ML diameter and a large AP diameter, and the medial side of the ischial bone and the lower part of the greater trochanter bearing weight simultaneously. He named CAT - CAM socket, many countries are in the trial and have new development constantly, such as: sciatic inclusion socket, which is also called the IRC socket (ischialram containment socket).

Suspension device

1. Belt, block belt, big head belt suspension is suitable for traditional leather leg, aluminum leg prosthesis suspension.

2. A Silesian belt is made of cloth or leather and can be used with a suction suspension. The belt is easy to use, comfortable, and has the function of controlling the rotation of the prosthesis. The disadvantage is not convenient as suction type suspension.

3. A gas valve is installed at the bottom of the suction suspension socket. When the socket bears weight, the residual limb is squeezed downward to discharge the bottom air. When the prosthesis is lifted, there is negative pressure at the bottom, which causes the prosthesis to suck on the stump. This kind of prosthesis does not need additional suspension device, easy to use, but when the circumference of the stump decreases, the prosthesis will leak and fall off.