Upper Extremity Prosthetics

Historically, advancements in prosthetic devices have been due to three

major factors, war, illness, and advancements in science and

technology. For upper extremity prosthetics we are in a period where

advancements are being made are being generated by technology.

Let’s take a look at some of these recent advancements.

Technology and Upper Body Prosthetics

It has been over 40 years since we first started seeing batteries and

transistorized circuit boards guiding the small electric motors of an artificial

hand. Shortly thereafter MIT developed electric elbows, and the technology

push was on.

As time passed, more powerful batteries were matched with smaller, more

powerful miniature electric motors providing for more useful and more

natural looking devices. Advancements in transistor circuitry eventually

allowed the use of electromyographic (EMG) in prosthesis. Use of

computers, in combination with EMG began to allow for more natural

movements, and more practical use.

Today’s Prosthetics

Today’s upper extremity amputees can take advantage of prosthetics that

are much more natural looking, and practical. The use of advanced

polymers is making it possible for devices previously made of metal to be

made of these new stronger plastics. The plastics continue to grow

stronger and may eventually replace metal devices.

Myoelectric motors have become smaller and more powerful, allowing for

more emphasis to be placed on aesthetics. In some cases, today’s upper

body prosthetics are almost indistinguishable from the limbs they replaced.

This has provided a greater self-esteem for many who are utilizing them.

Continuing advances in power supplies have also made a great impact.

Many of today’s devices have the benefit of being powered by disposable

batteries, something that would have seemed unthinkable in the not too

distant past, when large re-chargeable power sources were the norm.

Sensory Feedback

Today, studies and tests are proceeding with a variety of concepts using

sensory feedback. In some, nerve stimulation techniques are used, so that

nerve stimulation is proportional to the pinch force at the ends of a device.

Laboratory tests show that extended physiologic taction (EPT) can produce

near normal control of a terminal device by a patient.

Body Power

While much of the development of upper extremity prosthetics have

centered around hand and arm devices that are externally powered, that

seems to be changing. The focus is now on body powered devices. New

materials like high strength polymers are pushing the development of new

lightweight prosthetics. Polymer strands are woven into a strong fibrous

thread providing cabling that is more durable.

Advances in Terminal Devices

Traditional hook-type devices are being updated to improve strength,

durability and longevity. The use of composite plastics provide for

exoskeletal prosthetics that are attractive in appearance, and provide a

hollow interior for cables and actuation devices. In addition, rubber is being

replaced by these polymers providing better grip.

Upper body prosthetics continue to make advances daily. A limited market

keeps the costs high, and increased funding would certainly help the

development of these devices. Fortunately, advances in technology outside

of prosthetics are allowing researchers to take advantage of these

discoveries and apply them to more practical, easier to use, an

aesthetically appealing devices.