Prostheses - Prosthetics: Artificial Limb Information

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Rudimentary prostheses have been used since antiquity, to replace missing limbs, teeth, etc.; their use and sophistication has increased over time. In addition to the standard artificial limb for every-day use, many amputees or congenital patients have special limbs and devices to aid in the participation of sports and recreational activities.

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A Prosthetic is defined as an artificial substitute or replacement of a part of the body such as a tooth, an eye, a facial bone, the palate, a hip, a knee or another joint, the leg, an arm, etc. A prosthesis is designed for functional or cosmetic reasons, or both. A prosthesis is an artificial extension that replaces a missing body part. It is part of the field of biomechatronics, the science of fusing mechanical devices with human muscle, skeleton, and nervous systems to assist or enhance motor control lost by trauma, disease, or defect. Typical prostheses for joints are the hip, knee, elbow, ankle, and finger joints. Prosthetic implants can be parts of the joint, such as a unilateral knee. Joint replacement and arthroplasty mean the same thing.

An artificial limb is a type of prosthesis that replaces a missing extremity, such as arms or legs.

The type of artificial limb used is determined largely by the extent of an amputation or loss and location of the missing extremity. Artificial limbs may be needed for a variety of reasons, including disease, accidents, and congenital defects. Inside the body, artificial heart valves are in common use, with artificial hearts and lungs seeing less common use but under active technology development. Other medical devices and aids that can be considered prosthetics include artificial eyes, palatal obturator, gastric bands, and dentures.

Recently, there have been significant advancements in artificial limbs. New plastics and other materials, such as carbon fiber, have allowed artificial limbs to be stronger and lighter, limiting the amount of extra energy necessary to operate the limb. With advances in modern technology, cosmesis, the creation of life-like limbs made from silicone or PVC, has been made possible. Such prosthetics, such as artificial hands, can now be made to mimic the appearance of real hands, complete with freckles, veins, hair, fingerprints, and even tattoos. Cosmesis are attached to the body in any number of ways, using an adhesive, suction, form-fitting, stretchable skin, or a skin sleeve.

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There are Four Main Types of Artificial Limbs

These include the transtibial, transfemoral, transradial, and transhumeral prostheses. The type of prosthesis depends on what part of the limb is missing.

A transradial prosthesis is an artificial limb that replaces an arm missing below the elbow. Two main types of prosthetics are available. Cable operated limbs work by attaching a harness and cable around the opposite shoulder of the damaged arm. The other form of prosthetics available are myoelectric arms. These work by sensing, via electrodes, when the muscles in the upper arm moves, causing an artificial hand to open or close.

Transhumeral Prosthesis

A transhumeral prosthesis is an artificial limb that replaces an arm missing above the elbow. Transhumeral amputees experience some of the same problems as transfemoral amputees, due to the similar complexities associated with the movement of the elbow. This makes mimicking the correct motion with an artificial limb very difficult.

Transtibial Prosthesis

A transtibial prosthesis is an artificial limb that replaces a leg missing below the knee. Transtibial amputees can usually regain normal movement more readily than someone with a transfemoral amputation, due in large part to retaining the knee, which allows for easier movement.

Transfemoral Prosthesis

A transfemoral prosthesis is an artificial limb that replaces a leg missing above the knee. Transfemoral amputees can have a very difficult time regaining normal movement. In general, a transfemoral amputee must use approximately 80% more energy to walk than a person with two whole legs. This is due to the complexities in movement associated with the knee. In newer and more improved designs, after employing hydraulics, carbon fiber, mechanical linkages, motors, computer microprocessors, and innovative combinations of these technologies to give more control to the user.

Other less prevalent lower extremity cases include:

• Symes: This is an ankle disarticulation while preserving the heel pad.
• Knee disarticulations: This usually refers to an amputation through the knee, dis- articulating the femur from the tibia.
• Knee disarticulations: This usually refers to an amputation through the knee, dis-articulating the femur from the tibia.

There are several areas of technology that have advanced significantly recently and are showing considerable potential. Robotic limbs and direct bone attachment are two new technologies that have made tremendous gains recently.

Quick Facts Regarding Prosthetics

Prosthetics have been mentioned throughout history. The earliest recorded mention is the warrior queen Vishpala in the Rigveda. The Egyptians were early pioneers of the idea, as shown by the wooden toe found on a body from the New Kingdom. Bronze Roman crowns have also been found, but their use could have been more aesthetic than medical. With advances in medical science, a few experimental prostheses have been integrated with body tissues, including the nervous system. These highly advanced devices can respond to commands from the central nervous system, more closely approximating normal movement and utility than older prostheses.

100-Year History of Ottobock Prosthetic Legs - Ottobock - (2014-09-09)

U.S. Limb Loss Statistics

• One in 190 Americans is currently living with the loss of a limb. Unchecked, this number may double by the year 2050. In the year 2005, 1.6 million persons were living with the loss of a limb. Of these subjects, 42% were nonwhite and 38% had an amputation secondary to dysvascular disease with a comorbid diagnosis of diabetes mellitus. It is projected that the number of people living with the loss of a limb will more than double by the year 2050 to 3.6 million. If incidence rates secondary to dysvascular disease can be reduced by 10%, this number would be lowered by 225,000.
• In 2007, there are approximately 1.7 million persons living with limb loss in the U.S. (Unpublished paper from Johns Hopkins)
• The main cause of acquired limb loss is poor circulation in a limb due to arterial disease, with more than half of all amputations occurring among people with diabetes mellitus.

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