Posts Tagged ‘amputee’

When Amanda Kitts’s car was hit head-on by a Ford F-350 truck in 2006, her arm was damaged beyond repair. “It looked like minced meat,” Kitts, now 50, recalls. She was immediately rushed to the hospital, where doctors amputated what remained of her mangled limb.

While still in the hospital, Kitts discovered that researchers at the Rehabilitation Institute of Chicago (now the Shirley Ryan AbilityLab) were investigating a new technique called targeted muscle reinnervation, which would enable people to control motorized prosthetics with their minds. The procedure, which involves surgically rewiring residual nerves from an amputated limb into a nearby muscle, allows movement-related electrical signals—sent from the brain to the innervated muscles—to move a prosthetic device.

Kitts immediately enrolled in the study and had the reinnervation surgery around a year after her accident. With her new prosthetic, Kitts regained a functional limb that she could use with her thoughts alone. But something important was missing. “I was able to move a prosthetic just by thinking about it, but I still couldn’t tell if I was holding or letting go of something,” Kitts says. “Sometimes my muscle might contract, and whatever I was holding would drop—so I found myself [often] looking at my arm when I was using it.”

What Kitts’s prosthetic limb failed to provide was a sense of kinesthesia—the awareness of where one’s body parts are and how they are moving. (Kinesthesia is a form of proprioception with a more specific focus on motion than on position.) Taken for granted by most people, kinesthesia is what allows us to unconsciously grab a coffee mug off a desk or to rapidly catch a falling object before it hits the ground. “It’s how we make such nice, elegant, coordinated movements, but you don’t necessarily think about it when it happens,” explains Paul Marasco, a neuroscientist at the Cleveland Clinic in Ohio. “There’s constant and rapid communication that goes on between the muscles and the brain.” The brain sends the intent to move the muscle, the muscle moves, and the awareness of that movement is fed back to the brain.

Prosthetic technology has advanced significantly in recent years, but proprioception is one thing that many of these modern devices still cannot reproduce, Marasco says. And it’s clear that this is something that people find important, he adds, because many individuals with upper-limb amputations still prefer old-school body-powered hook prosthetics. Despite being low tech—the devices work using a bicycle brake–like cable system that’s powered by the body’s own movements—they provide an inherent sense of proprioception.

To restore this sense for amputees who use the more modern prosthetics, Marasco and his colleagues decided to create a device based on what’s known as the kinesthetic illusion: the strange phenomenon in which vibrating a person’s muscle gives her the false sense of movement. A buzz to the triceps will make you think your arm is flexing, while stimulating the biceps will make you feel that it’s extending. The best illustration of this effect is the so-called Pinocchio illusion: holding your nose while someone applies a vibrating device to your bicep will confuse your brain into thinking your nose is growing.

“Your brain doesn’t like conflict,” Marasco explains. So if it thinks “my arm’s moving and I’m holding onto my nose, that must mean my nose is extending.”

To test the device, the team applied vibrations to the reinnervated muscles on six amputee participants’ chests or upper arms and asked them to indicate how they felt their hands were moving. Each amputee reported feeling various hand, wrist, and elbow motions, or “percepts,” in their missing limbs. Kitts, who had met Marasco while taking part in the studies he was involved in at the institute in Chicago, was one of the subjects in the experiment. “The first time I felt the sense of movement was remarkable,” she says.

In total, the experimenters documented 22 different percepts from their participants. “It’s hard to get this sense reliably, so I was encouraged to see the capability of several different subjects to get a reasonable sense of hand position from this illusion,” says Dustin Tyler, a biomedical engineer at Case Western Reserve University who was not involved in the work. He adds that while this is a new, noninvasive approach to proprioception, he and others are also working on devices that restore this sense by stimulating nerves directly with implanted devices.

Marasco and his colleagues then melded the vibration with the movement-controlled prostheses, so that when participants decided to move their artificial limbs, a vibrating stimulus was applied to the muscles to provide them with proprioceptive feedback. When the subjects conducted various movement-related tasks with this new system, their performance significantly improve.

“This was an extremely thorough set of experiments,” says Marcia O’Malley, a biomedical engineer at Rice University who did not take part in that study. “I think it is really promising.”

Although the mechanisms behind the illusion largely remain a mystery, Marasco says, the vibrations may be activating specific muscle receptors that provide the body with a sense of movement. Interestingly, he and his colleagues have found that the “sweet spot” vibration frequency for movement perception is nearly identical in humans and rats—about 90 Hz.

For Kitts, a system that provides proprioceptive feedback means being able to use her prosthetic without constantly watching it—and feeling it instead. “It’s whole new level of having a real part of your body,” she says.

https://www.the-scientist.com/notebook/vibrations-restore-sense-of-movement-in-prosthetics-64691

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A Royal Marine who had his leg blown off, leaving his Liverpool FC tattoo missing a word and reading You’ll Never Walk, has defied the odds to become a runner and climber.

Andy Grant, 26, had his limb amputated after he stood on an improvised explosive device (IED) while on routine foot patrol in Afghanistan.

He had an operation to remove the leg below the knee and woke up to find the word Alone missing from his You’ll Never Walk Alone tattoo.

However, the father of three used the ironic inking as inspiration and went through vigorous rehabilitation sessions for 18 months.

He has not only learnt to walk, but is now closing in on a running world record.

Mr Grant, who lives in Liverpool and was serving with 45 Commando at the time of the blast, said he has always seen the funny side.

He said: “I am a huge Liverpool fan so had the Liver bird and the words to the song You’ll Never Walk Alone on my leg.

“The tattoo that I have been left with has always been a bit of a joke. I use it in my motivational speeches.

“It is ironic that it says I will never walk as I have gone on to run 10k in 40 mins. At the moment I am just two minutes off a record record for the 10k for a single leg amputee and I have that in my sights.

“It is bizarre and I just laugh about it. But it adds to my story I guess. The fact is that regardless of what the words says, the operation allowed me to walk and run and do so much else. You have got to see the funny side of it.

“I also won a couple of gold medals at the Invictus Games and got to abseil the shard so I don’t think I have done too badly.

“I guess I did use the tattoo I was left with as an extra inspiration. But I was always going to prove it wrong.”

The impact of the IED blast in Sangin six years ago severed Mr Grant’s femoral artery and took out a “big chunk” of his thigh. He broke both the fibula and tibia in his right leg and lost 6cm of bone.

But two years after the blast, the 26-year-old decided to have his right leg amputated after watching comrades with similar injuries enjoying activities with their prosthetic legs.

He can still recall the conversation he had with surgeon Anthony Lambert when he woke up.

Mr Lambert told him: “Well, we had to raise a flap of skin on your leg to cover the bone ends… and it’s meant that your Liverpool Football Club tattoos are a bit messed up. The Liver bird is a bit all over the place, and your tattoo now says ‘you’ll never walk’.”

The date of his blast, February 3, and the date of his amputation, November 25, are both anniversaries that Andy marks.

He said: “The anniversary of the blast is a bitter sweet day, but one that I like to get together with friends and family.

“I am very proud of my achievements and like to turn my story around to try and inspire other people about what they can achieve in the face of adversity.

“I am all about looking forward. I can not undo what happened and I have no regrets. I am all about making the best of a bad situation.”

Such is his positive outlook on life now, he says he feels like the bomb blast was “worthwhile”.

He said: “It’s been a rollercoaster ride of emotions, and it’s been bittersweet for me. On that day in 2009 I basically ended my career in the corps. I lost a bit of myself on that day and, as a 20-year-old I changed.

“It’s been hard when you look at it like that, but on the flip side I’ve had some amazing experiences that almost make it seem like it was worthwhile.

“It is weird to hear myself say that, but it just shows the level of recovery. It’s opened so many doors.

“My job as an inspirational speaker takes me around the world; I’ve started amazing relationships with people; I have three children and an amazing family; I’m looking to row across the Atlantic; and I’m hoping to be picked for the Paralympics next year.

“My life has moved on in an amazing way and it’s all down to what happened. It’s given me more of a life than I probably would have had.”

The Liverpool Football Club fan left the Royal Marines in May, 2012 and now works as a motivational speaker.

http://www.telegraph.co.uk/news/uknews/defence/11394618/Royal-Marines-Liverpool-FC-tattoo-reads-Youll-Never-Walk-after-amputation.html