The Wonderful World of Cosmesis

One woman notes that her lifelike prosthesis is so good that it now takes longer for her to get through airport security because when the metal detector rings, security doesn’t believe her when she tells them that she has an artificial limb. “They can’t see that my right forearm and hand aren’t flesh and blood, and they usually have to feel the prosthesis several times before convincing themselves,” says Kim Doolan. There are several reasons Doolan’s arm prosthesis “fools” people.

• It is painted to match her left arm and duplicate its subtle variations in color, especially around the knuckles and palm.
• It was carved especially for her based on an impression of her sound arm.
• It has acrylic fingernails that have lunulae (half moons) at the base and white tips.
• It has a clear, translucent, outer "skin" layer that acts like the epidermal layer of natural skin.

Another possible reason the arm looks so real, Doolan says, is because she doesn’t try to hide it. "I know most people won’t notice I’m wearing a prosthesis and that gives me confidence to keep it out in public and not hide it beneath long sleeves or inside pockets. That, in turn, means I walk with a more natural gait with both arms swinging at my sides and feel free to use my prosthesis to help me with various two-handed activities."

Mike Holt, president of a company that makes custom cosmetic prostheses, explains why this is important. "Traditional prostheses have been fabricated primarily to restore motor function with little emphasis on aesthetic appearance," he says. "In today’s socially oriented society, however, the artificial look of the prosthesis is not acceptable. This is especially true for those in public positions.”

Michael Kaczkowski, president of another company that makes cosmeses, makes the same point almost verbatim. Some of his company’s prostheses are designed to simulate the three dermal layers of skin and alleviate this problem as much as possible.

Though some people with limb differences prefer not to wear a cosmetic prosthesis and argue that it’s okay to be different, many amputees would rather blend in than stand out in a crowd.

“Although the first objective of cosmeses is to restore the appearance of injured limbs sufficiently to eliminate the stigma associated with the disfigurement,” Holt says, this does not mean that they are merely for aesthetic purposes and are not functional. “They can also improve the gait and posture, ease lower back pain, relieve pressure on bone spurs and other sensitive areas, protect the tissue from further injury, improve the operation of myoelectric hands, as well as belowknee and above-knee prostheses, and more.”

What Are my options?

When purchasing a cosmesis, you should be aware of the numerous options available today. The various materials and techniques used to make a cosmesis each have advantages and disadvantages that affect the durability, quality, accuracy, level of realism, and price of the final product.

Standard, off-the-shelf, cosmeses, which are made to a variety of standard sizes, are typically made from silicone or Polyvinyl Chloride (PVC) and usually provide only basic details, if any.

Advantages of Silicone Cosmeses Over PVC

• More lifelike
• More stain-resistant
• More colorfast
• More flexible
• More resistant to extreme temperatures and sun damage
• Less likely to cause reactions in the patient’s body
• More long lasting (Silicone cosmeses generally last for years, while PVC cosmeses, due to their tendency to stain easily, will usually need to be replaced in less than six months.)

Advantages of PVC Cosmeses Over Silicone

• Don’t tear as easily as some types of silicone
• Less expensive, generally costing in the hundreds of dollars.

Custom-made cosmeses, which are usually made of some type of silicone of varying degrees of quality, are more expensive (in the thousands of dollars), but offer much greater detail. "If appearance is critical, there is no comparison," says William J. Hanson, president of a company that provides both standard production and highdefinition custom silicone cosmetic covers for prosthetic limbs. "They can be supplied with extraordinary details, such as freckles, veins, special skin pigmentation, human hair and even tattoos if desired," he explains. "Females may want to apply nail enamel to their fingernails, and this can be accomplished by substituting acrylic for the silicone nails normally supplied with the covers. The goal is to match the unaffected limb as closely as possible for a natural look.

"Two methods are used for producing these high-definition silicone covers: creating a clear shell with a painted interior surface or blending pigment into the silicone," Hanson explains. "Painting the interior surface has been done for a number of years, but more recently, two companies have started blending color into the silicone. This provides a more durable cover because the color is uniform throughout. In addition, it produces natural ‘depth’ of the skin surface."

These high-definition cosmeses are expensive, however, and some companies have found a niche between those that offer them and those that offer the standard, off-theshelf, cosmeses that are inexpensive and offer little detail. One company, for example, offers custom-made, seamless silicone covers that are colored to match the patient ’s skin, but that do not have hair, wrinkles, age spots, and other details. By using color swatches that the company sends them, patients can tell the company which colors to use for the cover. To meet the needs of a diverse population, the company offers 26 standard colors. For realism, patients should specify their "base color," "suntan color," and, if they have dark skin, their "palm color." The patient never has to visit the company.

“The material is stable against chemical and photo-oxidation attack, is resistant to staining, will not absorb moisture, and has very high tear-strength,” says the company’s president, James G. Stuart. “Its elasticity makes donning and doffing easy and allows good movement of the underlying prosthesis.”

Another company offers “skin“ covers that also fit into this niche. These silicone covers for lower-extremity prostheses were engineered to be very affordable, have actual skin detail with the option of custom toes, and come in two elastic sizes. “Patients can just stretch them on and go,” says Kaczkowski, the company’s president. “They don ’t require glue or a heat gun to fit.”

Companies offering these products compete by offering higher quality than off-the-shelf cosmeses and by offering lower prices than those for more detailed cosmeses, explains Stuart.

What Other Materials and Techniques Do Companies Use?

In addition to silicone and PVC, other materials are used to make cosmeses. One company offers a cosmetic urethane “skin “ finish for prostheses that may be applied either by spraying or brushing. “Once applied, this finish provides a durable, waterproof urethane protective coating that is easy to clean and, when applied over a foam cover, has the texture and feel of actual skin,” says the company ’s president, Jeff Kingsley. “It is available in three standard shades that may be tinted to match most natural skin tones, and features, such as freckles or the appearance of hair, may be applied with the available tinting kit.”

The company also offers “a prefabricated, pull-on protective and cosmetic below-knee leg covering” that is made with the urethane “skin” applied to a cosmetic hose. This covering “provides a durable, waterproof urethane skin that is available in seven natural-looking shades,” Kingsley says.

Another company produces “skin” by spraying a vinyl or urethane solution onto a foam cover or by pulling a removable “skin” sleeve onto it. This company is also looking for innovative ways to make the “skin” look more realistic. One technique they are working on is airbrushing the “skin “ and matching it to a digital photograph of the patient. Stock or custom tattoos can also be added.

How Do Companies Make the Artificial Limb Look Like the Missing Limb?

Several companies have devised techniques to ensure that the cosmesis matches the remaining limb. One company, for example, makes extremely lifelike and accurate custom silicone cosmeses for upperand lower-extremity limbs. By using 3D high-resolution scanning and 3D printing, the company provides a replica, by reversal, of the sound limb. “This is achieved by using precision computer and digital imaging tools for processing each individual to capture and replicate size, true form and the fine details of skin, such as fingerprints,” says the company’s president, Thomas Ferrone. “For an exact match, comfort of fit, and quick, easy delivery, we use our patented processes joining the most advanced materials, computerassisted design and computer-aided manufacturing. A color match is achieved through our custom color matching process based on color calibration and a color confirmation procedure.”

Another company is currently trying to develop a new method of producing a cosmesis that it hopes will surpass existing methods in accuracy. Currently, the company uses the available CAD/ CAM technology as a starting point in their process. After scanning the sound limb with a TracerCAD unit, they then carve a matching limb on a large PDI carver.

How Are Cosmeses Attached to a Limb?

Companies use a variety of methods to hold cosmeses to the prosthetic limb, including adhesives, suction, and/or form fitting. In some cases, the cosmetic “skin” is sprayed or painted directly onto the artificial limb.

One company, for example, offers a “skin” product that is made of tough vinyl and can be brushed or sprayed onto an artificial limb. Afterward, the pigment can be applied to match the patient’s body. The company also offers a stretchable skin product, which was developed especially for above-knee prostheses. This “skin” is applied directly to a foam cover and will stretch as the prosthesis is bent. One of the company’s products, a “skin” sleeve, is especially interesting. Once the covering is placed over a prosthesis, it is heated and shrinks to fit.

Is There Any Room For Improvement?

Unfortunately, as good as modern cosmeses are, they do have limitations. They cannot change, for example, as human skin changes during certain activities and with exposure to the sun, Hanson explains.

Though some companies have developed ways to partly solve this issue, none are total solutions. Some companies offer, for example, products that temporarily darken the cosmesis and then fade with time to mimic the fading of a natural suntan. The dilemma that remains, however, is how to make the products fade at the same rate as patients’ actual tans so that their cosmesis will always match their skin.

Damage to cosmeses is also a major problem. Though many types of cosmeses are stain-resistant and, according to some companies, stainproof, they are expensive and should be treated with care. Hanson advises users to treat them as they would their own hands. “Any of them can be damaged so contact with harsh chemicals, abrasive surfaces, sharp objects and fluids that stain should be avoided,” he says. “When appropriate, rubber or work type gloves should be worn to protect them. When performing work tasks or hobbies that might damage hands and gloves, a powered gripper should be considered as an alternative to the prosthetic hand.” Once the task is finished, the patient can replace his or her cosmesis.

What About the future?

Though the state of the art of cosmesis is already at an extremely high level, there is always room for improvement, and cosmesis-manufacturing companies are always trying to make a better product – one that looks, feels and perhaps even functions just a little more like the real thing.

— by Rick Bowers