As Verne understood, the U.S. Civil War (during which
60,000 amputations were performed) inaugurated the modern prosthetics era in the United States, thanks to federal funding and a wave of design patents filed by entrepreneurial prosthetists. The two World Wars solidified the for-profit prosthetics industry in both the United States and Western Europe, and the ongoing War on Terror helped catapult it into a US $6 billion dollar industry across the globe. This recent investment is not, however, a result of a disproportionately large number of amputations in military conflict: Around 1,500 U.S. soldiers and 300 British soldiers lost limbs in Iraq and Afghanistan. Limb loss in the general population dwarfs those figures. In the United States alone, more than 2 million people live with limb loss, with 185,000 people receiving amputations every year. A much smaller subset—between 1,500 to 4,500 children each year—are born with limb differences or absences, myself included.
Today, the people who design prostheses tend to be well-intentioned engineers rather than amputees themselves. The fleshy stumps of the world act as repositories for these designers’ dreams of a high-tech, superhuman future. I know this because throughout my life I have been fitted with some of the most
cutting-edge prosthetic devices on the market. After being born missing my left forearm, I was one of the first cohorts of infants in the United States to be fitted with a myoelectric prosthetic hand, an electronic device controlled by the wearer’s muscles tensing against sensors inside the prosthetic socket. Since then, I have donned a variety of prosthetic hands, each of them striving toward perfect fidelity of the human hand—sometimes at a cost of aesthetics, sometimes a cost of functionality, but always designed to mimic and replace what was missing.
In my lifetime, myoelectric hands have evolved from clawlike constructs to multigrip, programmable, anatomically accurate facsimiles of the human hand, most costing tens of thousands of dollars. Reporters can’t get enough of these sophisticated, multigrasping “bionic” hands with lifelike silicone skins and organic movements, the unspoken promise being that disability will soon vanish and any lost limb or organ will be replaced with an equally capable replica. Prosthetic-hand innovation is treated like a high-stakes competition to see what is technologically possible. Tyler Hayes, CEO of the prosthetics startup
Atom Limbs, put it this way in a WeFunder video that helped raise $7.2 million from investors: “Every moonshot in history has started with a fair amount of crazy in it, from electricity to space travel, and Atom Limbs is no different.”
We are caught in a bionic-hand arms race. But are we making real progress? It’s time to ask who prostheses are really for, and what we hope they will actually accomplish. Each new multigrasping bionic hand tends to be more sophisticated but also more expensive than the last and less likely to be covered (even in part) by insurance. And as recent research concludes, much simpler and far less expensive prosthetic devices can perform many tasks equally well, and the fancy bionic hands, despite all of their electronic options, are rarely used for grasping.
Activity arms, such as this one manufactured by prosthetics firm Arm Dynamics, are less expensive and more durable than bionic prostheses. The attachment from prosthetic-device company Texas Assistive Devices rated for very heavy weights, allowing the author to perform exercises that would be risky or impossible with her much more expensive iLimb bionic arm.Gabriela Hasbun; Makeup: Maria Nguyen for MAC cosmetics; Hair: Joan Laqui for Living Proof
Function or Form
In recent decades, the overwhelming focus of research into and development of new artificial hands has been on perfecting different types of grasps. Many of the most expensive hands on the market differentiate themselves by the number and variety of selectable prehensile grips. My own media darling of a hand, the iLimb from Ottobock, which I received in 2018, has a fist-shaped power grip, pinching grips, and one very specific mode with thumb on top of index finger for politely handing over a credit card. My 21st-century myoelectric hand seemed remarkable—until I tried using it for some routine tasks, where it proved to be
more cumbersome and time consuming than if I had simply left it on the couch. I couldn’t use it to pull a door shut, for example, a task I can do with my stump. And without the extremely expensive addition of a powered wrist, I couldn’t pour oatmeal from a pot into a bowl. Performing tasks the cool bionic way, even though it mimicked having two hands, wasn’t obviously better than doing things my way, sometimes with the help of my legs and feet.
When I first spoke with
Ad Spiers, lecturer in robotics and machine learning at Imperial College London, it was late at night in his office, but he was still animated about robotic hands—the current focus of his research. Spiers says the anthropomorphic robotic hand is inescapable, from the reality of today’s prosthetics to the fantasy of sci-fi and anime. “In one of my first lectures here, I showed clips of movies and cartoons and how cool filmmakers make robot hands look,” Spiers says. “In the anime Gundam, there are so many close-ups of gigantic robot hands grabbing things like massive guns. But why does it need to be a human hand? Why doesn’t the robot just have a gun for a hand?”
It’s time to ask who prostheses are really for, and what we hope they will actually accomplish.
Spiers believes that prosthetic developers are too caught up in form over function. But he has talked to enough of them to know they don’t share his point of view: “I get the feeling that people love the idea of humans being great, and that hands are what make humans quite unique.” Nearly every university robotics department Spiers visits has an anthropomorphic robot hand in development. “This is what the future looks like,” he says, and he sounds a little exasperated. “But there are often better ways.”
The vast majority of people who use a prosthetic limb are unilateral amputees—people with amputations that affect only one side of the body—and they virtually always use their dominant “fleshy” hand for delicate tasks such as picking up a cup. Both unilateral and bilateral amputees also get help from their torsos, their feet, and other objects in their environment; rarely are tasks performed by a prosthesis alone. And yet, the common clinical evaluations to determine the success of a prosthetic are based on using only the prosthetic, without the help of other body parts. Such evaluations seem designed to demonstrate what the prosthetic hand can do rather than to determine how useful it actually is in the daily life of its user. Disabled people are still not the arbiters of prosthetic standards; we are still not at the heart of design.
The Hosmer Hook [left], originally designed in 1920, is the terminal device on a body-powered design that is still used today. A hammer attachment [right] may be more effective than a gripping attachment when hammering nails into wood.Left: John Prieto/The Denver Post/Getty Images; Right: Hulton-Deutsch Collection/Corbis/Getty Images
Prosthetics in the Real World
To find out how prosthetic users live with their devices,
Spiers led a study that used cameras worn on participants’ heads to record the daily actions of eight people with unilateral amputations or congenital limb differences. The study, published last year in IEEE Transactions on Medical Robotics and Bionics, included several varieties of myoelectric hands as well as body-powered systems, which use movements of the shoulder, chest, and upper arm transferred through a cable to mechanically operate a gripper at the end of a prosthesis. The research was conducted while Spiers was a research scientist at Yale University’s GRAB Lab, headed by Aaron Dollar. In addition to Dollar, he worked closely with grad student Jillian Cochran, who coauthored the study.
Watching raw footage from the study, I felt both sadness and camaraderie with the anonymous prosthesis users. The clips show the clumsiness, miscalculations, and accidental drops that are familiar to even very experienced prosthetic-hand users. Often, the prosthesis simply helps brace an object against the body to be handled by the other hand. Also apparent was how much time people spent preparing their myoelectric prostheses to carry out a task—it frequently took several extra seconds to manually or electronically rotate the wrists of their devices, line up the object to grab it just right, and work out the grip approach.The participant who hung a bottle of disinfectant spray on their “hook” hand while wiping down a kitchen counter seemed to be the one who had it all figured out.
In the study, prosthetic devices were used on average for only 19 percent of all recorded manipulations. In general, prostheses were employed in mostly nonprehensile actions, with the other, “intact” hand doing most of the grasping. The study highlighted big differences in usage between those with nonelectric, body-powered prosthetics and those with myoelectric prosthetics. For body-powered prosthetic users whose amputation was below the elbow, nearly 80 percent of prosthesis usage was nongrasping movement—pushing, pressing, pulling, hanging, and stabilizing. For myoelectric users, the device was used for grasping just 40 percent of the time.
2 million
In the United States alone, more than 2 million people live with limb loss, and 185,000 people receive amputations every year.
More tellingly, body-powered users with nonelectric grippers or split hooks spent significantly less time performing tasks than did users with more complex prosthetic devices. Spiers and his team noted the fluidity and speed with which the former went about doing tasks in their homes. They were able to use their artificial hands almost instantaneously and even experience direct haptic feedback through the cable that drives such systems. The research also revealed little difference in use between myoelectric single-grasp devices and fancier myoelectric multiarticulated, multigrasp hands—except that users tended to avoid hanging objects from their multigrasp hands