The Science Behind How Prosthetic Hands Work

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The Science Behind How Prosthetic Hands Work

When you or a loved one experience the loss of a hand due to amputation or abrupt trauma, there are options for a custom prosthetic hand that will help you regain mobility and functionality.

A prosthetic hand can improve your quality of life by allowing you to engage in many of the same activities you participate in before the loss of a limb. There are passive, or non-functional, prosthetic hands that are devised mainly to approximate the look of biological hands. But when it comes to functional prosthetic hands, these devices can give you varying range of motion and control of movement depending on the type of prosthetic hand you can receive. You may be wondering, “how does a prosthetic hand work?” Scientific advancements have resulted in a range of high-functioning prosthetic hand options, with more innovations on the horizon.

Body-Powered Prosthetic Hands

As the name suggests, the scientifically-engineered “power” that enables body-powered prosthetic hands to work is human movement, rather than an external energy source. A harness and cable system makes up the main connecting structure of this type of prosthetic hand. Because the hand is powered by you, specific body movements can trigger the hand’s ability to open or close.

The two most common types of body-powered prosthetic hands are known as voluntary opening or voluntary closing. Voluntary opening prosthetic hands allow the hand to open when you put pressure on the cable system, with the hand closing on its own once that pressure is released. The opposite action powers a voluntary-closing prosthetic hand – the hand is naturally open, but pressure must be applied to close it. For people with limited strength, the voluntary-open option is usually recommended by your prosthetist.

Electric-Powered Prosthetic Hands

Myoelectric prosthetic hands harness the power of your nerves and muscles in the residual arm in order to “teach” the prosthetic hand how to move. Modern myoelectric hands rely on sophisticated, rechargeable batteries to power the connecting transmitters.

With training, the hand “learns” what the signals from contracted muscles in the residual limb are meant to accomplish, and becomes trained to react accordingly. For most people, electric-powered prosthetic hands are more comfortable and realistic-looking than body-powered prosthetic hands. It’s important to understand, however, that they need regular recharging and there’s a significant training period involved in teaching the prosthetic hand to react to various muscle signals.

With myoelectric prosthetic hands, the type of neuro-muscle needed, and signal detection components that are connected to the hand, depends largely on the amount of the residual limb remaining. Above-elbow amputees have transmitters that are attached to their biceps and triceps, while below-elbow amputees rely more heavily on their forearm and wrist muscles.

Advanced Systems

Prosthetics with fingers that can move individually represent the forefront of emerging prosthetic hand technologies. A new wave of prosthetic hands are expected to expand the possibilities of the current technology, where the existing limb gives information to the prosthetic hand. Devices with connecting electrode arrays are being developed that will allow the prosthetic hand to provide information about what it is touching – just like biological hands.

With this technology perfected, you won’t need to see what your prosthetic hand is touching in order to know when something is touching it, when things are hot or cold, or how much pressure should be applied in order to move or grip something efficiently.

If you or a loved one are interested in learning more about the options available for a prosthetic hand in Arkansas, contact Horton’s Orthotics & Prosthetics today at 501-683-8889 to set up an appointment with one of our certified clinicians.

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