What if every time you walked, you had to think: stairs coming up — slow down — bend knee and lift right leg to first stair — lock right knee, bend left knee and lift leg to second stair. Careful — uneven terrain ahead — walk slowly and be careful not to fall. Try to avoid that bumpy spot.¹

For people who have had a transfemoral (above the knee) amputation, thinking like this is essential for mobility.¹ Without biological knees, their bodies are unable to plan, execute, and compensate for actions that the rest of us take for granted. The good news is that technological advances are making artificial limbs more functional. This module will provide nurses with information about how people learn to use a prosthesis, types of lower extremity and upper extremity prostheses, advances in prosthetic technology, and resources for amputees.

Learning to Use a Prosthesis

A prosthesis is a device that is designed to replace, to the extent possible, the function and/or appearance of a missing limb or body part.² The prosthetist is a skilled professional who fabricates artificial limbs using a variety of synthetic materials.

In the first year after surgery, a new amputee spends a great deal of time with a prosthetist, as during this period, there are dramatic changes in the shape and size of the residual limb.³ Not all patients are candidates for a prosthesis. The amputee’s and family’s motivation to learn the skills needed to use and care for a prosthesis is vital.

A person who was not ambulatory before an amputation is unlikely to use a prosthesis. The person’s age and the level of amputation are the most important factors affecting a successful rehabilitation outcome.⁴ Increasing age and higher levels of amputation present significant challenges to the rehabilitation team.

Those with hip or knee contractures will not fully benefit from using a prosthesis. Patients with cardiovascular or respiratory disease may not have the energy reserves to use a prosthesis, and those who have cognitive, neurological, or visual impairment may jeopardize their safety by using a prosthesis.

Those who are prosthetic candidates must learn several important skills to gain maximum benefit from a prosthesis. The person must learn how to don (put on) and doff (take off) the prosthesis correctly. Amputees also should learn how to care for the prosthesis to extend its life; sometimes, insurance doesn’t cover the cost of frequent replacements.

The most important component of any prosthesis is the design and fit of the interface where the skin of the residual limb meets the surface of the prosthetic socket. When beginning to use the prosthesis, the person increases wearing time gradually. All amputees must be taught to inspect the skin of the residual limb for redness or irritation each time the prosthesis is removed.

If any signs of potential skin breakdown are present, the prosthesis should not be reapplied until skin redness or irritation disappears.^2,5 Weight changes of even 5 pounds may affect the fit of the socket and can result in skin breakdown of the residual limb.

Because people with diabetes often have a sensory loss due to neuropathy in their residual limb, they may not know if their prosthesis is causing skin irritation, because they are unable to feel it. People with diabetes must do a thorough skin inspection using their senses of touch, sight, and smell to detect signs of skin breakdown and infection.^2,5,6

For older adults with lower extremity amputations, the type of prosthesis available depends on the patient’s Medicare prosthetic functional level.

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Medicare Prosthetic Functional Levels

0  No ability or potential to move about or to transfer (e.g., move from bed to chair)

1  Ability to transfer or move about on level surfaces at a fixed cadence

2  Ability or potential ability to move about and to maneuver low-level barriers like curbs

3  Ability or potential ability to walk at a variable cadence

4  Exceptionally active individuals such as athletes or children

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Older adults usually are assigned to a functional level 1 or 2. As the functional level increases, the person has access to more sophisticated prosthetic components. Older people may be motivated to increase their rehabilitation efforts when they understand how increasing a functional level can benefit them.

Lower Extremity Prostheses

The goal for a person with a unilateral lower extremity amputation is to be able to ambulate safely and independently on level surfaces, stairs, ramps, and curbs with or without assistive devices. The most important goal for someone with a lower extremity amputation is to learn how to transfer safely. This ability, more than walking, is the key factor for self-sufficiency and independent living.⁷ About 70% of those with lower extremity amputations use their prostheses full time — donning it in the morning, using it during the day, and doffing it at night.⁸

Amputees must consider a number of factors in selecting a prosthesis, including their age, height and weight, activity level, the level of amputation, and mobility needs.² The energy needed to use a prosthesis must also be considered. A person with a bilateral transfemoral amputation will use up to 250% more energy in walking than they would have required using their own legs.⁸ As a result, older people and those who have impaired health states with bilateral lower extremity amputations may choose to use a wheelchair for mobility. What type of prosthesis to use and when to use it also depend on the individual’s ability to learn and his or her problem-solving skills.⁹

Single axis knees that move in only one direction are the lightest and most durable type of prosthetic knee. The most basic single axis knee requires the most muscle power to operate and allows users to walk at only one speed. These problems can be reduced by using fluid-controlled knees that automatically increase or decrease the time the leg is off the ground as the person changes walking speeds.² Amputees who have had a lower extremity amputation and who are able to use a walker or crutches usually are able to make good progress with a prosthesis.

Because those whose amputations are the result of vascular abnormalities such as peripheral vascular disease and diabetes are at high risk of cardiovascular disease, exercise testing is indicated before they start an exercise training and prosthetic rehabilitation program.

Upper Extremity Prostheses

It’s helpful to fit a person with a unilateral upper extremity amputation with a temporary prosthesis, because early fitting prevents the person from becoming accustomed to one-handed activities and discarding the idea of using a prosthetic device.¹⁰ Some people with an upper extremity unilateral amputation may prefer to use their residual limb without a prosthesis, because their ability to feel with their residual limb is an advantage over using a prosthesis. An upper extremity amputee can also learn to function well using his or her other hand, the residual limb, the feet and/ or assistive devices.⁸ The person with a bilateral upper extremity amputation is dependent on prosthetic devices for independent function and is most likely to accept and use the prostheses.

The distal end of an upper extremity prosthesis is known as a terminal device. People with upper extremity amputations need to decide whether they will primarily use a hook or an artificial hand as a terminal device. It is possible to have several interchangeable hooks and hands.

A hook is more functional because it allows the person to grasp small items with precision, it weighs less than a cosmetic hand, and is more reliable and requires less maintenance.¹⁰ Another important advantage of a hook compared to an artificial hand is that a hook allows the person to more easily visualize the item being handled. (The bulkier hand may cover up the item.)

This feature is especially important, as tactile sensation has been lost. However, because an upper extremity prosthesis is harder to use than a lower extremity prosthesis, may be cosmetically less attractive, and is less likely to be used for function if the unaffected arm is functional, some amputees with an upper extremity amputation select a nonfunctioning prosthesis with a cosmetic hand.¹⁰

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Upper Extremity Prostheses

• Passive prostheses provide a cosmetic replacement of the limb with limited gripping functions.
• Cable-operated prostheses have a variety of hooks, hands, wrists, elbows and shoulder joints.
• Electric prosthetic systems use an external power source such as a motor or gears.
• Hybrid systems use a combination of body-powered and electric options to create individualized systems.

• Adaptive prostheses have numerous adaptations that are customized or applied for specific activities, such as for sports, recreation or vocational needs.

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To fabricate an upper extremity prosthesis, the prosthetist makes a plaster cast of the residual limb and from that cast, makes a socket that fits onto the person’s limb very closely. Once the socket is fabricated, the prosthetist attaches it to the person’s body using a harness-type device.¹⁰

It’s important for the socket to fit the person’s residual limb closely for comfort and acceptability.¹⁰ It’s not uncommon for people’s limbs to change over time, especially if they have lost their arm in an accident, the most common way to lose an arm.

Advances in Prosthetic Technology

Microprocessors and lighter materials are making prostheses more functional than ever before.

Lower extremity prostheses: Options for prosthetic feet have increased from a few basic models to more than 50 varieties. Amputees can now select prosthetic feet designed for walking, running, dancing, golfing, cycling, swimming, and skiing.²

Much like the human foot, prosthetic feet today are energy-returning, meaning they store and expend energy to make walking with a prosthetic foot easier and less tiring.¹¹ A dynamic response foot is available for people at a Medicare functional level of 3 or 4.

This type of foot is much like a sophisticated spring that cushions when the heel strikes the ground and then uses the absorbed energy to push the foot into the next step. The spring action at toe-off propels the prosthesis through the swing phase of the gait, and the pattern then repeats. This phenomenon is known as energy return, meaning that a high percentage of the energy expended when the user steps forward is stored within the foot system and then returned as momentum for each successive step.¹¹

Computerized knees are able to compensate for changes in walking speed and provide safety and comfort for their users. Amputees who use computerized knees have a more natural gait, can sit and stand with ease, and can kneel and walk on all types of surfaces.¹ However, the most advanced knee system is not necessarily the optimum choice for every amputee. For some people, safety and stability are more important than functional performance.¹²

Upper extremity prostheses: Just 25 years ago, upper extremity amputees were restricted to a few cumbersome and intimidating prostheses, all with limited functionality.¹³ Today, the continuum of available prostheses ranges from being primarily cosmetic to being mostly functional.10 New technologies such as batteries, microcomputers, circuit boards, and other electronic devices allow upper extremity amputees greater function. Composite plastic and silicone materials are being used to produce lighter-weight designs and to fabricate more natural-looking prostheses.^10,14

Complex systems of bionic control are being developed. It has been demonstrated that a monkey’s brain signals were able to control a robotic arm as the monkey watched the arm from a computer. Although current technology allows the amputee to move the hand only as a unit rather than moving each individual finger, robotic technology might allow the individual to control all the fingers of an artificial hand.¹⁵

Even though the field of bionics is still developing, a variety of hand-like terminal devices are on the market to help upper extremity amputees. Four types of body-powered electrical terminal devices are available for upper extremity amputees: hooks, a functional hook known as a prehensor, artificial hands, and specialty terminal devices.¹⁵ Prehensors have some features of both a hook and a hand, allowing the person to grasp and hold objects.

These devices consist of a thumb-like component and a finger component and resemble pliers or lobster claws. Prehensors are not as cosmetically attractive as artificial hands, but like hooks, they are better able to offer visual feedback to the amputee, because they cover up less of the item being handled.¹⁵

Although no single product is able to replicate all the functions of a human hand, it is often possible for amputees who have more than one terminal device to easily and quickly switch from one type of device to another using quick-disconnect wrist units. Myoelectric control, using both the person’s muscle power and electrical stimulation, is the most effective, comfortable, and natural way to control artificial arms and hands.

Small stainless steel electrodes are placed on the skin, where they sense the electrical activity of the muscles. These muscle signals are electronically amplified and used to move the hand as desired. Viewers of the television program “ER” were able to see the myoelectrically controlled Utah Arm 2 used by the character Dr. Robert Romano.

The Utah Arm system for transhumeral (above the elbow) or higher amputees costs between $50,000 and $70,000. The cost is covered by most insurance companies and Medicare.16 If the cost is not paid for by insurance, less expensive prostheses that use both electric and body-powered systems are available.¹⁶

Researchers are working to develop an “artificial synapse chip” that may be able to serve as an interface from a prosthetic limb to the brain. Although this type of technology is in its earliest developmental stages, experts believe computer chips will play an increasing role in all types of prosthetic devices.10 Advances in prosthetic technology can potentially provide people who have lost hands with replacement hands fitted with connections to nerve endings in the biceps and triceps within the residual limb. Using this technology, the upper extremity amputee would have the ability to control his handgrip by clenching or relaxing different muscles.¹⁰

Although it is understandable for a person to want a prosthesis with the latest high-tech components, amputees should be informed about several issues before choosing an artificial limb. First, it’s easy to become sidetracked by the bells and whistles and miss out on the basics.³

New amputees should ask about the appropriate technology and devices that will facilitate their individual rehabilitation program. As function improves and needs and skills change, a more complex device may be appropriate.³ Second, what works for one person might not be as successful for another person, even one with a similar amputation.³ Third, it takes time for the newest technological prosthetic devices to be developed and to reach the market at a cost that insurance plans will cover.

Resources for Amputees

The Amputee Coalition of America sponsors an online support group for amputees who don’t have access to a local support group, those who are physically or emotionally unable to attend a support group, and those who would like support in addition to what they are already receiving from a local group.

The coalition also publishes InMotion, an award-winning bimonthly magazine for amputees; First Step: A Guide for Adapting to Limb Loss; Side Step, a guide for amputees with diabetes; and Military In-Step, a publication for people whose amputation was the result of a war injury. Some support groups have amputee members who will visit individuals having an amputation both before and after surgery. The person then has the opportunity to ask questions and to see the potential for quality of life after an amputation.

Early prosthetic fitting and training, physical rehabilitation, and early psychological support can promote functional recovery.⁵ A prosthetic program is successful when the person views the artificial limb as having added value to his or her quality of life. Physical therapists can support people with amputations by providing encouragement and support, by teaching them how to care for a prosthesis, and by suggesting resources that can help them network with other amputees and learn about rapidly evolving improvements in artificial limbs.

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