In the case of a disarticulation amputation, which is where the actual knee joint has been separated, several advantages are offered to the amputee. This operation offers a better suspension of the prosthesis, more comfort when walking, better control over the prosthesis and faster rehabilitation. In short, a through-the-knee amputation makes a perfect suspension system for a prosthesis.
Unlike an above the knee amputation where the weight of the prosthesis is supported by the buttocks through the Ischial Tuberosity, a through-the-knee amputation allows a prosthesis to cling to the femoral condyles, so that the weight of the prosthesis is distributed around the remains of the knee joint. The extra length afforded by a through-the-knee amputation gives the amputee far better leverage, and suspension of the socket is greatly improved. The bigger the femoral condyles, the better, as the socket takes hold of the central part of the condyles, getting a good grip to preclude the socket from slipping off.
In a case where the condyles are not so prominent and the outer part of the remaining joint is the same size as or smaller than the rest of the limb, a seal in-liner is used to create an excellent suction suspension. A custommade silicone liner can also be made from a cast of your stump. This is extremely comfortable, allows the prosthesis a good suspension and lasts a long time.