Advances in Prosthesis

Thursday, May 24, 2007
By Marrecca Fiore

Newer technologies are making prosthetics more functional than ever before.
The use of microprocessors and lighter materials has made the devices easier to use and maneuver.
Examples of how far the technology has come could be seen a few months ago in amputee, Heather Mills turn on Dancing with the Stars and, more recently, in efforts by South Africa’s Oscar Pistorius to become the first amputee runner in the Olympics.
It's estimated that about 1.9 million or one out of every 200 people has had some kind of amputation, according to the Amputation Coalition.
Prosthetics have long helped people regain the functionality of a lost limb. And today, they’re available for just about every body part from legs and arms, to heart valves and breasts.
“Some of the biggest advancements include the use of thermal plastics and composites, which have made the prosthetic lighter and stronger,” said Brad Ruhl, vice president of sales and marketing for technical orthopedics at Otto Bock HealthCare. “There’s also been a lot of advancements in terms of design that really help people function at a higher level.”

Microprocessor Technology
Microprocessors, powered by electronic and computer technology, are nothing new to the field of prosthetics. What is fairly new, however, is the use of the technology in the lower extremities.
“It’s been around for 15 or 20 years,” said Joe McTernan, director of reimbursement services for the American Orthotic & Prosthetic Association. “What’s primarily come into play in recent years is its use in knees and feet.”

The C-Leg and Ossur’s power knee and Propio foot are some examples of the latest and greatest technology in prosthetics, said McTernan.
“With microprocessor technology, electrodes are placed over the socket of the limb and the patient is trained that when they flex certain muscles, it sends a signal to the motor to do a specific motion,” he said. “So the electrode picks that signal up and that, for example, causes the hand to open or close.”
The technology has made impressive strides in knee technology, said McTernan. Whereas the traditional prosthetic knee uses a hydraulic cylinder that has to be adjusted for more or less resistance, a knee using microprocessor technology is more fluid and acts more like an anatomical knee, he said. “One of things that this allows a patient to do that they couldn’t do before is walk foot over foot downstairs,” McTernan said. “Before, you would have to lock the prosthetic knee and basically drag that leg down the stairs. Even going down a hill, you would have to lock the knee in place and kind of drag the leg. So what it’s really done is allowed people to walk more naturally.”

Likewise, new technology in foot prosthesis uses carbon fiber for better flexibility when moving from one gate to the next. In some cases, a prosthetic foot is able to take a reading from a non-amputated foot so that the two feet will always be in proper alignment, said McTernan.
Two-thousand-eight Olympic hopeful Pistorius runs on a pair of "Cheetahs," which are j-shaped blades made of carbon fiber. Born with lower leg and feet defects, Pistorius had both legs removed below the knee when he was 11-months-old.

The Future of Prosthesis By far the most exciting advancements in prosthetics are still a few years off from hitting the commercial market. A team of researchers led by Johns Hopkins University’s Applied Physics Laboratory (APL) has developed a prosthetic arm prototype for the Defense Advanced Research Projects Agency (DARPA) that can be controlled neurally.
“What this means is that your mind would think about making a movement and your hand or arm would do it,” said Otto Bock’s Ruhl. “It’s truly the first step toward the kind of bionics you used to see on television.”

In recent years, the use of vacuum technology in which the prosthesis is attached to limb using a suction-like method has allowed amputees to remain active, even competing in sporting events like the Paralympic Games. “Before vacuum technology, which really allows the prosthetic to fit to the body intimately, athletes would have to worry, if they were running for example, literally about their leg coming out from under them,” Ruhl said. “Now it’s about pushing the limits and trying to see how far amputee athletes can go.” Ruhl said researchers are also studying the possibility of skeletal attachment in prosthesis. “With direct skeletal attachment you would eliminate the need to attach the prosthesis to a socket and give (the amputee) absolute confidence in the limb reattachment,” Ruhl added. “So hopefully this is also something we’ll see down the road.”

Some Facts about Prosthesis
These are some basic facts about prosthesis provided by the Web site, ineed2know.org. For more information, visit http://www.ineed2know.org/prosthetics.htm.
What are prosthetics?
Prosthetics are artificial appliances used to replace or restore human body parts in order to regain the lost functionality of the missing part.

What types of prosthetics are available?
Prosthetics are available for almost every body part and for just about every condition. Amputees benefit greatly from prosthetic limbs, which help them to regain the ability to walk or use their hands. Women who have had a mastectomy can benefit from prosthetic breasts in the form of implants. People with bad hips or knees can have these replaced with prosthetic alternatives and enable them to get up and moving again. Even prosthetic heart valves are available.

How do prosthetics improve your quality of life?
Prosthetics help people regain control over their lives and the ability to do things for themselves. They can walk around without assistance and tie their own shoelaces. Regaining control over your life is the most often cited reason of how a prosthetic can improve the life of an amputee.

What are some of the latest improvements in artificial limbs?
One of the best examples of advances in prosthetics technology is the myoelectric hand, a device fitted with a computer chip that can sense when you give a brain command to grasp something. Even though a person may have lost a hand, he or she can still tie a shoelace using this prosthesis. With the aid of computer technology and digital imaging, prosthetics are fitting better, lasting longer and providing a more natural look and feel to amputees.

How much does an artificial leg cost?
A simple prosthetic leg can cost around $2000, but once the prosthetist's costs and the latest mechanical and computer-aided devices are integrated, costs can range up to $10,000 or $15,000. This does not include the cost of maintenance required on the prosthetic leg.
This article was reviewed by Dr. Manny Alvarez