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When the National Academy of Sciences established the Artificial limb Program in 1945, the options for amputees were few: crude, wooden prostheses. And for those who chose none: life confined to a wheelchair. Fast-forward 65 years and the United States faces an influx of amputees from the conflict in Iraq, but the opportunities for soldiers returning home from war with an amputation are far more advanced. Listed are some of the most important advancements in robotic prosthetics in the last 20 years that give artificial limbs more function than ever before.
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1. Prosthetic Foot Materials
For years, wood was the dominant material for a prosthesis. But over the last 20 years, materials have emerged to give greater comfort and confidence for amputees. Susan Kapp, an associate professor of orthotics and prosthetics at the University of Texas Southwestern School of Health Professions, says if a prosthetic foot is cut open, most likely the material found inside is carbon fiber. Carbon fiber, according to Kapp, is a much more life-like material, giving amputees a sense of life in their foot. Thermoplastic sockets give prosthesis recipients extended comfort at the site the prosthesis is fitted, and titanium gives a prosthesis longer life and durability.
U.S. Army/ Roger J. Mommaerts Jr.
Bluetooth technology made the jump from the cell phone industry to prosthetics in 2007 when Marine Lance Cpl. Joshua Bleill received two artificial legs after seeing combat in Iraq. Each leg was fitted with a Bluetooth device. Bluetooth is more often recognized for its ability to connect pieces of technology together without the use of wires. In Bleill’s case, the Bluetooth devices communicate with each other to regulate stride, pressure and speed in the prosthetic legs. The benefit of Bluetooth technology, according to Ryan Blanck, a prosthetist at the Center for Prosthetics and Orthotics at Brooke Army Medical Center in Ft. Sam Houston, Texas, is the programmability of the software. “We can take that technology an further develop it to adjust to a patients need,” Blanck said.
3. Microprocessor Knees
With an onboard computer within the prosthesis, people with above-knee amputations have greater control over walking, stopping and moving on inclines. These “robotic” knees, termed microprocessor knees, analyze the pressure an amputee puts on the missing limb. Also contained within the knee is a fluid control unit, which the microprocessor monitors to appropriate joint resistance when walking on inclines. Available since the early 1990s, microprocessor knees have revolutionized the arenas of safety and stability for people without knees. Kapp says people that receive the prosthesis don’t have to worry about the knee buckling under them.
Touch Bionics Inc. and Touch EMAS Ltd.
4. Myoelectric Technology
When the i-LIMB hand debuted in the United Kingdom in July 2007, people caught a glimpse of the future of robotic prosthetics. The i-LIMB applies myoelectric technology, where the prefix myo- denotes a relationship to muscle. Myoelectric prostheses are controlled by placing muscle sensors against the skin at the site of amputation. The electric signals generated by the muscle at an amputee’s stump controls a processor aboard the prosthetic. This myoelectric technology allows for greater control and precision in the five fully functional digits, enabling recipients to perform everyday tasks such as picking up coins and opening tabbed aluminum cans.
5. Targeted Muscle Reinnervation
Amputees are in the infant stages of controlling prostheses directly with their minds. Through targeted muscle reinnervation, the nerves from the amputated limb are reenergized in a different part of the body, for example, the chest. When an amputee wants to use their arm in a particular fashion, he or she thinks the action, prompting the nerves in the chest to react. That reaction sends a message to a microprocessor in the robotic limb, which performs the action. Currently, there are only 35 people in the world with TMR limbs, and Blanck has fit 14 of them. He says the ever-changing prosthetic field aims to allow an amputee think about their prosthesis in a way that is normal. Jesse Sullivan (left) was the first man to receive this treatment technique from the Rehabilitation Institute of Chicago, and Claudia Mitchel (right) was the first woman to receive it.
When the Boston Marathon turned into a life-or-death situation for so many runners and spectators Monday, several who survived expressed immediate gratitude -- even those who lost limbs in the attack.
But how does the body survive without an arm or a leg?
The immediate trauma is physical: According to medical reports, two of Monday’s 10 or so amputees lost their limbs at the site of the bombings. The others underwent surgical amputation at the hospital.
Loss of blood is the main life-threatening concern, doctors said. Near the finish line, doctors and bystanders wrapped gauze tourniquets around legs.
"The major risk at that point is that you bleed to death," said Dr. Alberto Esquenazi, chairman of Einstein Healthcare Network's Department of Physical Medicine and Rehabilitation and chief medical officer for MossRehab Medical Center in Pennsylvania. "If there's nothing to hold the blood, you go into cardio shock, and as a result you die."
Most of the worst injuries seemed occur to the legs, because the bombs exploded close to the ground. How fast you bleed depends on where the limb was severed, said Dr. Terrence Sheehan, Chief Medical Officer at Adventist Rehabilitation Hospital of Maryland and medical director of the Amputee Coalition. The closer to the hip, the larger the blood vessels and the harder to stop the bleeding.
"That's why the first responders were very important," Sheehan said.
Time is also of the essence to save the limb, Sheehan said: Without blood flow, limbs can survive anywhere from one to six hours. Once in the operating room, surgeons are trained to salvage the limb and reattach it if at all possible, both doctors said.
"That's the mindset of the surgeon, to save the limb: amputation is seen as failure," Sheehan said.
But on Monday, there wasn’t much question that many of the patients’ limbs could not be salvaged.
The operating rooms at Boston Medical had multiple surgeons to make team decisions, Dr. Tracey Dechert, a trauma surgeon at Boston Medical, told The New York Times.
"What we like to do is before we take off someone's leg -- it's extremely hard to make that decision -- is we often get two surgeons to agree," Dechert said.
Time is of the essence when it comes to surviving limb amputation. iStockPhoto
A team approach in the operating room is also important, Sheehan said, to ensure the future success of adapting to a prosthesis. Sheehan likes to have a vascular surgeon, an orthopedic surgeon, a plastic surgeon and sometimes a peripheral nerve specialist collaborating during surgery.
"What they do at that point is going to affect the person all the way down the line," he said. "The skin need to be closed in a certain way so we’re able to work with a person who will need to have a prosthesis. If someone has an exposed nerve or a bone not appropriate handled, they'll end up with problems with their prosthesis later."
After the risk of blood loss is over, the next level of risk is infection, Esquenazi said. The heat from the explosive device may have sterilized the pieces of metal that wedged into limbs, but infection is still possible.
Some patients whose limbs were damaged at the marathon but still intact may face future choices about amputations, Esquenazi said. Soldiers with similar blast injuries sometimes choose amputation over multiple surgeries, he said. Amputation can allow someone to start rehab faster and get back to their new normal life.
After surgery, it can take a while for the body to realize a limb is gone.
"In some instances I have had patients who would try to get out of bed when they awake in the middle of the night not realizing their leg is not there anymore," Equenazi said. "The body is resilient and has memory, but eventually it adjusts."