There are many types of above knee prostheses. The type that an amputee is fit with depends on the shape of the residual limb, the length of the residual limb, activity level, prognosis, and individual preference. An AK amputee is unable to bear weight on the bottom of his residual limb. In order to keep the weight off the bottom of the limb, the amputee must support his body weight on the ischial tuberosity (seat bone), the soft tissue of the limb, and the gluteal tissues. Therefore, the AK amputee will always feel some pressure because he is essentially sitting on top of the socket. In order to hold the prosthesis onto the person’s body, a method of suspension must be used. The possibilities for suspension are suction suspension design and locking liner suspension designs.
With suction suspension the user pulls their residual limb into the socket with a donning sleeve which pulls through the bottom valve, bringing all tissues into socket, and once the valve is placed into socket the suction is kept with no air travel ensuring suction suspension.
Locking liner suspension requires a roll-on silicone suspension liner with locking capability onto the residual limb. The locking liner has a pin or a pull strap or lanyard design on the bottom end that locks into the bottom of the socket.
A prosthetic sock is worn over the silicone insert in order to allow for volume fluctuation.