THE celebrity magazine People has ranked fashion model and actress Aimee Mullins among the world鈥檚 50 most beautiful people. She is president of the Women鈥檚 Sports Foundation, whose goal is to advance the lives of girls and women through sport and physical activity, and is herself a record-breaking athlete. Mullins is also a double amputee, having lost both her legs below the knee as a child.
She now has new legs, just not of the traditional type. 鈥淧eople say I have no legs, but in fact I have 10,鈥� Mullins says. The pair she uses to race in are made of carbon fibre, for example, and shaped like cheetah legs. For more glamorous occasions she has a more shapely pair with sexy shoes attached.
Mullins doesn鈥檛 look on herself as disabled. New technology combined with a positive attitude have transformed the way she sees her condition from a disability in need of a cure into an opportunity for human enhancement. She is not alone. Earlier this month, Mullins joined a host of others 鈥� amputees, athletes, composers, technologists and quadriplegics among them 鈥� at the Massachusetts Institute of Technology to discuss the myriad ways that technological innovation is challenging our perception of what it means to be able-bodied or disabled. Frank Moss, director of MIT鈥檚 , which staged the events, went further: 鈥淭his is a quest to blur the distinction between human ability and disability,鈥� he told the gathering.
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The technologies they discussed are a world away from a simple wheelchair or hearing aid. Many are starting to have previously undreamed-of, and deeply enabling, benefits. Take the story of 48-year-old Annette Coker, who in August 2002 was left paralysed from the shoulders down by a car accident. Two implants placed into her chest, and a dozen smaller electrodes in her neck and arms, now stimulate Coker鈥檚 muscles to move, allowing her to lift food to her mouth, scratch her head and even brush away the odd tear. 鈥淚t brings back a little bit of the independence that I had before the accident,鈥� she says. Being able to use her hands encourages others to view her as normal, she says.
Ultimately the goal is to get people like Coker up and walking. A more immediate aim is to make it easier for her, and others, to control their implants, which at present Coker activates by moving her neck muscles. Researchers would like these people to be able to do this using their thoughts alone. 鈥淭he brain signals will control the arm,鈥� explains of Brown University in Providence, Rhode Island, who is working toward this goal with researchers at Case Western Reserve University in Cleveland, Ohio, which developed the technology behind Coker鈥檚 implants.
Donoghue hopes to achieve this by linking this technology to another he is developing that has allowed Matt Nagle, who was paralysed from the neck down after being stabbed six years ago, to check his email, play a video game and move a prosthetic arm, using just his thoughts (New Scientist, 15 July 2006, p 28). To do this, the team plans to link the two technologies by developing a way to take the signals captured by the implant in the brain and transmit them to the electrodes in the muscles.
Other quadriplegics are being helped to develop their artistic talents. Dan Ellsey is a 32-year-old live-in patient at the Tewksbury Hospital in Massachusetts who is paralysed from the neck down by cerebral palsy. Though Ellsey cannot speak, he has just become a composer and performer of his own music.
To do this he uses software, originally developed by Media Lab researcher Tod Machover to help children with no musical training to compose melodies. The idea is that the children 鈥渄raw鈥� notes as lines on a computer screen, which the software interprets and tidies up to produce a tune. To allow Ellsey to start composing, Machover and colleague Adam Boulanger adapted the software so that it can accept inputs from an infrared light Ellsey wears on his head, allowing him to alter the volume and timing of the piece in real time using only head movements.
On 9 May, Ellsey鈥檚 live performance at the Media Lab meeting was greeted by a standing ovation. 鈥淎ll of Dan鈥檚 physical problems sum up to a primary barrier in communication,鈥� Boulanger says. 鈥淲orking with music enables him to combat the most fundamental aspects of his disease.鈥� As well as breaking down barriers that confront people with restricted physical function, such work 鈥渇undamentally changes our perceptions of what it means to have a disability鈥�, he adds.
Hugh Herr, a biomedical engineer at the Media Lab, agrees. 鈥淲hat you will see in the future is more and more examples of someone viewed by society as deficient beginning to exhibit augmentation,鈥� he says. Herr, who lost both legs while climbing, aged 17, is convinced that prosthetics will one day give people greater abilities than ordinary bodies do. 鈥淩ight now the Paralympics is slower than the Olympics. In future they will be faster. We are at the cusp of that change.鈥�
Running to the future
One athlete who personifies this change is Oscar Pistorius, a man happy to be known as the 鈥渇astest thing on no legs鈥�. In March he won a silver medal at the South African national athletics championships, running the 400 metres in 46.56 seconds. It was an able-bodied race, yet Pistorius is a bilateral amputee who uses carbon fibre 鈥渃heetah鈥� legs similar to the ones Aimee Mullins wears. The International Association of Athletics Federations is now debating whether Pistorius should be allowed to run in able-bodied races at future international meetings. Those who argue against him doing so claim his legs might give him an unfair advantage.
Most prosthetic leg specialists say such concerns are ill-founded, for now at least. The prosthetic legs, which are made by the Icelandic company Ossur, act like springs which store energy as the foot is pushed into the ground, and then return much of it to the runner, just as tendons do in a natural ankle. However, unlike natural legs, the Ossur prosthetics lack the muscles to generate their own power, and so provide much less energy overall than natural legs, the experts say.
That may be about to change. Herr, who has made it his life鈥檚 work to design improved prosthetic legs, is being funded by the US Department of Veterans Affairs to work on a prosthetic ankle that returns more energy in each stride. Inside each prosthetic are battery-powered motors that do a similar job to muscles. Last week, he wore two of these brand-new ankles for the first time. 鈥淚t was absolutely amazing,鈥� he says. 鈥淚t鈥檚 like hitting the moving walkway at the airport.鈥� People wearing the new prosthetic have been shown to expend 20 per cent less energy when walking than with a standard prosthetic, and Herr says their gait also looks completely natural.
Advances like these are shifting perceptions of disability. Herr mentions a 17-year-old girl who has decided to go ahead with an operation to amputate a damaged leg because, he says, she thinks a new prosthetic will give her more athletic ability than she has now. For his own part, Herr claims he would not swap his prosthetic legs for natural legs, even if he could. 鈥淲ould you buy a computer system if you were told you couldn鈥檛 upgrade it for 50 years?鈥� he says.
His goal is to create an artificial leg that outperforms a natural leg in every way. In the meantime he will focus on specialised designs for particular purposes: one that allows him to run faster than other humans, another that allows him to walk more efficiently and a third that allows him to climb better. 鈥淚 mean, Aimee and I can just switch legs in a matter of 15 seconds.鈥� That鈥檚 not something able-bodied people can do.
