The prosthetic exoskeleton sits bolt upright in a chair, looking as if a robot has stood up, walked away and left part of itself behind. Roughly three minutes later Kevin Oldt is strapped into the metal frame and ready to stand. He closes his eyes and takes a deep breath, stretching his arms away from his body like a high diver about to take a plunge. Except Oldt holds a crutch in each hand, and when it’s go time he pushes upward with his powerful arms. The exoskeleton’s four electric motors kick in with a low whir, straightening Oldt’s lower body as he steadies himself with the crutches.

Once Oldt is standing, a physical therapist checks the exoskeleton’s settings on a digital screen connected to its back support, and gives him the okay. Oldt takes a few steps, looks up and says, “I’m learning how to walk all over again.”

When a 49-year-old man says that, one assumes he has been through something terrible. For Oldt that was a snowmobile accident more than 14 years ago that injured his spine and left him in a wheelchair. After more than a decade of physical therapy and hard work he is back on his feet several times a week, with the help of a robotic medical exoskeleton.

More science than fiction

The device offers Oldt the support his legs no longer provide. “It almost feels like I am walking, with a little bit of help from the motors,” he says as he strides across the room, the exoskeleton clicking and purring. His steps are surprisingly fluid, given that they are a combination of the machine’s programming and the remaining strength in his legs. The exoskeleton’s software calibrates how much assistance Oldt needs by sensing how much force he generates as he lifts his foot off the ground and pushes forward. “I’m always trying to use my mind to initiate my leg to go forward,” he says, his forehead moist from the effort it takes to work with the device. “I look down because I can’t feel my feet, but I can at least see where they’re going.” That, he says, helps reconstruct the missing connection between his mind and his body.

Mechanical exoskeletons have been in development for decades, but for most of that time the focus was on creating hydraulic-powered suits that soldiers could wear to carry heavy loads. These exist mostly in the form of prototypes as the U.S. government’s Defense Advanced Research Projects Agency (DARPA) and contractors try to figure out how to make them practical for military operations, in terms of cost and logistics.

But Oldt’s exoskeleton—the Ekso GT, made by Ekso Bionics—and a variety of similar products from other companies have had much more impact in recent years on medical rehabilitation for spinal cord injury patients. In April the GT became the first exoskeleton approved by the U.S. Food and Drug Administration for use with stroke patients as well as patients suffering injuries as far up the spine as the cervical region (just below the neck), thanks to the device’s tall back plate. In March the FDA granted Parker Hannifin Corp. approval to sell its Indego robotic exoskeletons both to hospitals and directly to patients. Argo Medical Technologies—makers of the ReWalk exoskeleton—is reportedly the only other company that can sell directly to patients. In December 2015 the U.S. Department of Veterans Affairs began covering the cost of the ReWalk exoskeleton for eligible paralyzed veterans.

Standard care is very hands-on—two or three physical therapists often support and guide each step a patient takes. Often one of those therapists must manipulate the patient’s legs if the patient does not have the strength to move. That technique can be effective over time in helping patients regain some strength and mobility in their lower bodies, but measuring a patient’s progress is difficult and the work is very strenuous for therapists and patients alike. Another recent option has been assistive standing devices such as Hocoma’s Lokomat, which places a patient in an exoskeleton suspended by cables over a treadmill. Patients walk on the treadmill with the Lokomat exoskeleton’s help but do not have the untethered freedom that freestanding exoskeletons provide.

Robotic rehab

Exoskeletons such as the one Oldt uses require a single therapist. They can be tuned to provide varying levels of support to meet different patients’ needs, and they measure a patient’s progress more precisely. This leads to more effective therapy sessions, says Tom Looby, Ekso Bionics’ president and CEO. During a patient’s first rehabilitation session a team of physical therapists working without an exoskeleton can normally get that person to take eight “quality” steps, meaning the patient is not trying to contort his or her body to compensate for a lack of strength or balance, Looby says. He claims the same patient in an Ekso GT can take 400 quality steps during that first session.

Robotic “gait trainer” exoskeletons like these have become increasingly popular as a rehabilitation option, says Liza McHugh, a physical therapist at Kennedy Krieger Institute in Baltimore. The GT enables individuals with paralysis to have long therapy sessions during which they are able step in a way that “we believe is good for restoring the nervous system after spinal cord injury,” McHugh says, adding that Kennedy Krieger has treated dozens of patients with the device since it arrived in August 2015.

The latest exoskeletons allow therapists to measure and document statistics including the length and number of steps, how much power the suit’s motors are using to assist a patient, and how the patients shift their weight as they step. This allows therapists to measure progress more precisely than in the past, McHugh says, explaining that physical therapists have traditionally judged progress based largely on subjective observations.

Working out the kinks

But exoskeletons still have several drawbacks. In addition to being expensive—one can cost $70,000 to $150,000—and requiring a lot of special training for therapists, they are designed to be used only on surfaces that are solid, dry and level, McHugh says. A patient’s ability to walk in the clinic might not translate to wet, sandy or uneven terrain. The Ekso GT is adjustable for heights only between 1.5 and 1.8 meters, so “we are unable to use it with our pediatric population,” she adds.

There is also a lack of concrete evidence that exoskeletons are more successful than conventional physical therapy at rehabilitating patients. Ekso is sponsoring a study that compares the progress of 160 spinal cord injury patients undergoing rehabilitation with the GT, with hands-on therapy and with no therapy, over 12 weeks. In August the company enrolled its first patient in its WISE, or “walking improvement for spinal cord injury with exoskeletons,” clinical trial.

“Generally, all things being equal, those using exoskeletons are able to get more therapy—do more work—in a shorter amount of time,” says Dylan Edwards, WISE’s lead investigator and director of the Burke Medical Research Institute’s Laboratory for Non-Invasive Brain Stimulation and Human Motor Control in White Plains, N.Y. Edwards and his colleagues plan to evaluate whether robotic gait training can improve a patient’s walking speed—progress that would indicate that the brain, spinal cord, peripheral nerves and muscles are beginning to work together more effectively. The researchers will also evaluate patient pain and muscle spasticity, as well as economic factors such as number of physical therapists and staff required during training. “I’m trying to build an argument that we should embrace this technology in the physical therapy profession,” Edwards says.

Iron Man

Kevin Oldt is perhaps the best endorsement for exoskeletons thus far. He has been helping promote its technology for the past several years through demonstrations for the press and public. He says he relishes the relative freedom that wearing the Ekso GT gives him, even for a brief amount of time. And he claims that consistent use of the exoskeleton three days per week for the past few years has helped him regain some strength and motor control in his legs.

Oldt acknowledges that the technology needed to help him walk again with minimal or no exoskeleton help is years away. Still, his experience has given him hope. “Sixteen years ago there was nothing,” he says. “This was just a comic book design—reading about Iron Man. Now it’s reality.”