Articles from prior issues of The Advocate

January/February 2000


External Prosthetic Devices Improving both function and looks are goals for the prostheses fitters.
Success depends a great deal on the condition of the remaining limb part.
by Mark Pratt, Minnesota DDS

ANNALEISE FURLONG PROVIDED THE NADE National conference with an informative presentation on external prosthetic devices. She devotes her time to fitting artificial arms and legs to amputees for both improved function and cosmetic reasons. She told the audience that 65 percent of all lower extremity amputees are 65 years of age or older, most of whom have peripheral vascular disease (PVD). PVD as the underlying cause of lower extremity amputation creates particular problems when fitting artificial legs and feet because leg tissues are so susceptible to infection and pressure sores. Furlong said that peripheral neuropathy is also a major hurdle to overcome. This is also a factor to consider in traumatic amputations where nerve damage has occurred. Peripheral neuropathy can also create major rehabilitation problems. Furlong stated, "Imagine what it would be like, not knowing where you were setting your foot down because it has no feeling. Is your leg under you properly, or is it too far forward or rearward?" She reported that many people give up completely on prosthetics because of falls or near falls. Medicare pays according to the level of total function that is expected for each patient. Heart disease or allergic reactions to the materials that might decrease exercise tolerance could mean limited funds for a device. Furlong said that below the knee prostheses can cause pressure sores when they are fitted. Care is taken to remove enough bone to allow a flap of calf muscle to wrap under the bones and to the front of the leg, forming a cushion. She pointed out that the skin on the legs is very different from the skin on the soles of the feet. It is thinner and cannot bear much pressure. She passed around various devices to show different ways to attach prosthetics and to illustrate the materials. Titanium is extremely strong and lightweight but expensive. To prevent an imbalance that would make walking harder, the trick is to create a limb weighing about the same as a real one, she said. Properly fitted and balanced, a below knee prosthesis takes thirty-five percent more energy too walk than normally required. An above knee prosthesis takes up to sixty-five percent more energy. Fitting a device is a real world task. Furlong said that after surgery, a shaping sock or ace wrap is placed on the limb to shape the surrounding tissue. This is done on both leg and arm amputations. As the patient's activity level increases, the site surgery site changes shape. This is why they first fit a temporary device that is expected that is expected to last three to twelve months, after which an assessment of activity level is done. The devices that Furlong demonstrated were varied, based on the expected function. Some were lifelike, down to the detail of revealing blood vessels and matching skin tones. These had endoskeleton (inside) stiffeners to allow for cosmetic materials on the outside. Devices with exoskeletal (outside) stiffeners allow construction workers to kneel without tearing apart the device. Some had joints that allowed flexion, making walking wearer and more natural. Each was different to allow for whatever the wearer felt was most important. Furlong stated that the life expectancy is three-to-five years for year device. Some intricate prostheses cost $15,000 to $20,000, plus an expected ten percent annual upkeep expense. She also showed an artificial arm fitted with an electronic ability to grasp at a cost of a mere $30,000. The user operates it by flexing arm muscles to press switches that open and close the hand. Questions arose about repairing or recycling the used equipment to keep costs lower. Furlong said liability issues in the U.S. prevent their reuse here. They are not wasted because they are sent overseas