Parts of prosthesis vary according to the type of prosthesis used and its function. Prothesis is created and fixed to the person as a replacement of a limb or other body part.
Prosthesis has 4 main parts.
The interface of the prosthesis is the part that attaches the residual limb (called stump) to the body. This is usually made up of various thin cushion materials.
Gel cushion interface is worn over the residual limb and protects the skin from abrasive movements. It helps to even out the pressure on the limb due to weight of the body. Irregular stump contours (formed due to scars, sharp bones or burns) are fitted with custom molded interfaces. Ideally, a person is given 2 interfaces so that they can change it everyday. Usually interfaces are recommended to be replaced every six months at least.
Prosthetic sock can be replaced or worn with a gel interface. Socks made of wool, nylon or synthetic fabrics sometimes have gel sandwiched between the layers of fabric in varying thicknesses to suit the person. The size of the residual limb may change in the course of the day as a result of activities, weather and various other factors. Wearing multiple layers of socks or removing some layers helps in managing the changes.
Suspension is the component that helps the prosthesis to hold on to the residual limb. The following suspension systems are used commonly.
For lower limbs, components such as microprocessor-controlled ankles and knees may be fixed to provide greater stability and safety. They also reduced the energy spent to move the stump to have an effect to move the prosthesis and reduce stress to nearby joints and the backbone too.
For upper limbs, prosthesis is provided with fully functioning shoulder and arm controlling electronic components. Myoelectric upper limb prosthesis uses the natural electric signals of a person’s muscles. Muscle activity is detected by the electrodes in the socket and the signals are transmitted to the operative unit of the prosthetic hand, wrist and/or elbow.
Appearance or cover of the prosthesis:
People who want to make their prosthesis appear anatomically natural use a soft foam material that is equivalent to the density and consistency of the muscles and tissue covering the plastic and metal components. Such materials and coverings also reduce damage to clothing worn over them. However, they may increase the weight of the prosthesis.