Prosthetic Limbs

Prosthetic Arms

Introduction to Prosthetic Arms

Prosthetic arms are artificial limbs used to replace missing arms which may be amputated due to disease or trauma. These artificial arms serve as great tools for the amputees to restore some of the capabilities lost with their amputated natural arms. In some cases, prosthetic arms represent an aesthetic gift for the amputees because there are many people who are concerned about their physical appearance without an arm.

The History Of Prosthetic Arms

In ancient times, most prosthetic arms were mostly made of wood and iron held together with leather attachments. It would not be difficult to conjure up an image of a ferocious pirate with a wooden peg arm or a warrior with an iron cast for his hand. The choice of raw material for making these prosthetic arms reflects that these prosthetic limbs are merely props to conceal an embarrassing deformity.

These materials used in the earlier days made the artificial arms bulky and heavy, illustrating that the focus of these prosthetic arms was not for function. This also highlights the fact that the study of prosthesis did not take much flight until the 16th Century where a French doctor, Ambroise Pare, successfully invented hinged mechanisms for prosthetic limbs. In the early 1800's, a big breakthrough occurred in the history of prosthetic arms when an advanced prosthetic arm was invented that was controlled by the opposite shoulder.

The biggest difference between ancient prosthetic arms and modern prosthetic arms is the choice of material. Contemporary prosthetic arm designs opt for the lightweight but strong and durable carbon fibre as the base material.

Key Components Of A Prosthetic Arm

The pylon acts like the skeletal frame in ensuring a good overall support structure. It can be further developed to imitate a real arm by adding plastic material to the pylon and then dyeing this material to match the amputee's skin colour. The socket is the part of the prosthetic arm which attaches to the amputee's limb stump. It is important that a socket is fitted tightly yet comfortably so that it does not cause any irritation to the skin and allows the amputee to maximise the use of the prosthesis optimally. Therefore, the socket is assisted by a prosthetic sock to ensure a good fit. The suspension system mainly helps the prosthesis in attaching itself to the body. Some systems function using a harness system such as using straps and leathers and other systems rely on using suction to secure the prosthesis.

Powering The Prosthetic Arm

There are a few ways of powering the prosthetic arm for it to work. One way is to body-power it by using cables fastened with a harness to the opposite shoulder. This opposite shoulder is then manipulated in certain directions to control the prosthetic arm. Another way of powering the prosthetic device is to use motors. There will be a main control switch which the amputee can manipulate. By pressing buttons in a certain sequence, the prosthetic arm can perform a specific task. Using this sequence-control method will then allow the amputee to perform a variety of tasks according to the different sets of sequential codes.

Another method known as the Myoelectric method to control the prosthetic arm uses the reading of the contractions of muscles by electrodes fastened to the skin surface. As muscles can deliver small electrical signals when they contract, electrodes will measure the muscle contractions and send a message to the prosthetic arm to perform a certain task. As technology advances, we can be sure that there will be more varied and creative methods to power the prosthetic arm.