A prosthetic leg is a prosthesis, or artificial limb, that is attached where the leg has been amputated due to a trauma or disease. Although such legs may vary greatly, all modern ones have three major components: the pylon, the socket and the suspension system. Additional features are dependent on the type of amputation that has been performed.
Traditionally made of metal rods, the pylon is the skeleton of the prosthetic leg and acts as a support structure. More recently, pylons have been made of carbon and fiber composites that are much lighter. Sometimes the pylon may be covered by foam or plastic, which can be formed and dyed to match the amputee’s skin tone to give a more natural look.
The socket is the part of the prosthetic leg that connects the prosthesis to the stump, or residual limb. A socket transfers forces from the prosthesis to the stump, which requires that the socket is carefully fitted so it doesn’t damage or irritate to the skin. The socket is attached to the limb over a liner and sometimes a prosthetic sock to assist with a comfortable fit.
The suspension system is the mechanism responsible for keeping the prosthesis attached to the body. The type of suspension system is dependent on the type of amputation that was performed. Some suspension mechanisms operate on suction, while other artificial legs are attached by using a harness system. Patients who have undergone a transfemoral amputation, or an amputation above the knee, will need a harness system, whereas patients who have undergone a transtibial amputation, or an amputation below the knee, will possibly be able to use a suspension system that relies on suction.
In addition to the type of suspension system used in a prosthetic leg, whether or not an amputation was transfemoral or transtibial dictates other features. For example, a patient who has undergone a transfemoral amputation will need to have a prosthesis that has an artificial knee. Even though all prosthetic legs have the three basic components and additional features, it is important to remember that each limb is custom made for the comfort and function of the amputee.
After an amputation has been completed and the swelling has gone down, a plaster mold is taken of the stump. This mold is used to make a duplicate stump for the purpose of fitting the prosthetic leg as it is being constructed. After the artificial limb is finished, adjustments are made through trial and error during multiple physical therapy sessions.