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.
