Volume 2, 2002

First Step - A Guide for Adapting to Limb Loss, A publication of the National Limb Loss Information Center

Manufacturers and Distributors of Assistive Devices for U/E

Amputees Advanced Peripheral Technologies

Edward Niziol
E-mail: NizioLynch@aol.com

Hosmer Dorrance Corporation

Hunter Digital

LC Technologies, Inc.
E-mail: requests@eyegaze.com

Maddak Inc.

Madentec Limited

Origin Instruments Corporation

Otto Bock

The Propagated Development Group

Sammons Preston

Texas Assistive Devices, LLC

TRS Inc.

United States Manufacturing Company (USMC)


Assistive Devices Give Upper-Extremity Amputees a Helping Hand

image: spork used at meal

Simple, complex products make life easier for prosthetic and nonprosthetic users

by Rick Bowers

Though upper-extremity amputees, especially those with congenital limb differences, are remarkably adaptable in most situations, they, like all human beings, sometimes need a "helping hand." Some prefer to rely on their residual limb, their other hand, their feet, and the assistance of simple devices; others prefer to take advantage of more complex items like actual artificial hands, or prostheses. Whatever the individual amputee chooses, the necessity for assistance often leads to interesting adaptations of existing products or, in some cases, inventions.

Simple devices to help the nonprosthetic user

Performing tasks doesn’t always require complex devices. Amputees who do not want to use prostheses can often take advantage of much simpler items like shoes with Velcro laces that can be closed with one hand, double-sided tape, shirts with snaps, neck slings to help hold tools, and clip-on ties to make their lives easier. A simple cutting board with stainless-steel nails driven through it and protruding through can be used by one-armed nonprosthetic users to hold items like fruit and vegetables for cutting or peeling. Sammons Preston offers a simple device called a Pant Clip, which can help unilateral upper-extremity amputees pull up and button their own pants.

image: lady using Dressing StickMaddak Inc., offers a one-hand cutlery set that allows one-arm amputees to use a single device to cut and eat their food and dental floss holders that make flossing possible. One of the company’s more interesting devices is The Eatery - a relatively simple device that helps bilateral upper-extremity amputees eat independently without prostheses. Both Sammons Preston and Maddak Inc., offer elastic shoelaces that make it possible to slip in and out of shoes without tying or untying laces. Other devices from the two companies include: button loops that help upper-extremity amputees guide buttons through buttonholes; a dressing stick that makes dressing easier, writing instruments that can be held by a toe, and adjustable head pointers or mouth sticks that can hold a pen or be used to turn pages.

For bilateral upper-extremity amputees, toileting is one of the most difficult activities. image: the Winsford FeederAn easily installed bidet for the commode in the home can be very useful. With certain models, the control handle, which controls the water stream and the air for drying, can be manipulated using a mouth stick with a long metal hook.

On the more-complex end of the spectrum are devices like self-propelled lawn mowers, which can be purchased from numerous companies, and the Winsford Feeder, an automatic setup that helps people with no arms eat independently. A switch can be activated by a head or chin motion, which causes a spoon to go to the food and bring it back to the mouth of the user. The Winsford Feeder is available from Sammons Preston.

Taking advantage of computer technology

Computers are everywhere today, and the ability to use them can open up the world for upper-extremity amputees, giving them access to information, a social life, and even employment. For people with no hands or only one hand, however, using a computer that requires typing on a keyboard and moving a mouse may seem almost impossible. Although some amputees type with a one-handed keyboard or with a pen or pencil held between their teeth, the need or desire for something more efficient has again led to invention. Many products exist now that allow computers to be set up to operate totally hands-free - no prosthesis required!

Words+ and Origin Instruments Corporation offer the wireless HeadMouse, which can, as the name implies, be operated by movements of the user’s head. A sip/puff switch or software can be used to perform the clicking function. image: Head MouseThe HeadMouse can also be used with an on-screen keyboard, which helps the user write letters and use the Internet. Madentec Limited, Advanced Peripheral Technologies, and numerous other companies have similar devices available.

The Propagated Development Group and Hunter Digital offer a foot-controlled mouse, and The Propagated Development Group offers TouchKeys, a product that allows users to type with a mouse. An Infrared/Sound/Touch (IST) Switch, available from Words+, and the Eyegaze System, distributed by LC Technologies, Inc., make it possible for computer users to operate numerous devices and software with the blink of an eye or almost any type of body movement. Some might also want to consider speech-recognition or voice-activated software, which is offered by several companies. Some programs even allow users to do computer programming. Those who prefer prostheses Some amputees prefer to use prosthetic devices, like artificial hands, hooks, prehensors, or other terminal devices.

For example, amputee Edward Niziol’s favorite meal was a good steak dinner; however, it was difficult for him to manipulate the steak knife with his prosthetic hand. So he invented and patented a prosthetic knife to insert in his prosthetic arm to give himself and other amputees better control when cutting their food. When not eating, the amputee can simply push a lever on the prosthesis, and the knife moves out of sight.

image: N-Abler II (wrench attachment shown fixing gate)Amputee Ron Farquharson, co-owner of Texas Assistive Devices, LLC, also wanted a product that could help him cut things, but, ultimately, he invented a product that could do much more. In 1991, Farquharson (pronounced far-kwer-sun) co-invented the N-Abler - a terminal device for the end of an arm prosthesis that is a stable holder for a variety of inter-changeable tools. Over 100 tools, such as specially modified wrenches, pliers, hammers, knives, forks, spoons, fishing rods, and gardening tools, are now available for the device.

While the prosthetic knife and the N-Abler allow single-function tools to be used on the end of a prosthesis, hooks and prehensors like the GRIP and the Electric Greifer (Gripper) are functional terminal devices that perform many tasks.

Hosmer Dorrance Corporation and United States Manufacturing Company (USMC) both offer hooks, which are typically body-powered, but sometimes electric.

David W. Dorrance, the original designer of the "Split Hook," patented the device in 1912. Dorrance, who had lost his hand in 1909 in a sawmill accident, was unhappy with the immovable single hooks of the time that were similar to the well-known "pirate’s hook," so he went to work to produce something better. The split hook design he developed offered much more functionality in that it allowed the hook to be used for more than merely hooking onto things; the split hook allowed items to be squeezed and held between the hooks. Today, the company offers a wide variety of split hook designs.

Though many people prefer artificial hands for cosmetic purposes and, in the case of electric arms, for greater grip, the split hook also has many advantages. Using a hook, amputees can better see what they are trying to hold, while the size and thickness of artificial hands sometimes block their view. Because artificial hooks and hands can’t feel, being able to see what one is doing is important. This also makes hooks generally better for picking up smaller objects. Also because hooks are usually made of metal, amputees don’t have to be as careful around heat, which can melt artificial hands.

Among Hosmer Dorrance’s most popular hooks is the No. 7. "I call the No. 7 hook the Swiss Army Knife of prosthetic hooks," says John Michael, CPO and president of CPO Services Inc., an independent consulting firm. The No. 7 hook image: a prosthetic hand, a standard hook and a quick-disconnect wrist from USMCincludes a pail hook, a nail and chisel holder, and a knife grip as part of the hook and has a wider opening to allow for holding things like shovels and broom handles. A quick-disconnect wrist offered by the company allows users to switch from a hook to a regular hand with the push of a button.

USMC also offers a body-powered split hook and quick-disconnect wrist, as well as an easy-flex wrist that allows amputees to flex and lock their wrist at 45-and 65-degree angles so that they can better reach the midline of their body with their hook.

Somewhere between a hook and a hand are devices called prehensors, like the GRIP, which is produced by TRS Inc., and the Electric Greifer, which is produced by Otto Bock. These devices consist of a thumb-like component and a finger component and resemble lobster claws or pliers.

image: The Grip 3 and the Grip 2S from TRS, Inc.These devices are not as cosmetically pleasing as artificial hands, but like hooks, they are better able to offer visual feedback to the amputee. While most hooks are voluntary-opening, which means that the user must apply force to open the hook which then closes on its own with the aid of rubber bands, the GRIP is a voluntary-closing device, meaning that force must be applied to close it instead of to open it. Voluntary-opening devices are limited in their closing strength by the strength of the bands. Voluntary-closing devices, on the other hand, are only limited by the user’s strength and can be controlled incrementally. In addition to visual feedback, voluntary-closing devices provide a tension feedback similar to the "feeling" experienced when using bicycle handbrakes.

image: boy fixing bike using Electric GreiferThe Electric Greifer has a number of additional advantages: It is voluntary-opening and voluntary-closing, it allows very wide opening, it includes built-in wrist flexion, it is battery-powered, and it is myoelectric, which allows it to take advantage of the body’s own muscles for control. Its disadvantages are its heavy weight and its inability to be immersed in water.

Some amputees choose to use hooks or prehensors like the GRIP or Greifer, while others choose to use artificial hands. It is a matter of choice and depends a lot on what the amputee needs. In some cases, amputees choose to use different devices for different purposes.

By taking advantage of the myriad devices available to help them, upper-extremity amputees - whether they wish to use prostheses or not - should be able to accomplish almost any task. Sometimes, though, when no satisfactory product exists, amputees might have to do what Edward Niziol, Ron Farquharson, David W. Dorrance, and Bob Radocy (the inventor of the GRIP) did - they might just have to invent their own

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