For “Finish,” a sculpture he installed at the Lincoln Park Zoo, Terry Karpowicz used industrial tubes painted gold to form a figure crossing a finish line to reach a goal.

And 40 years after losing much of his right leg in a motorcycle accident, Karpowicz can finally feel that elation.

Karpowicz, 67, is one of the first to test a new prosthetic leg, developed by researchers at the Rehabilitation Institute of Chicago, that responds to its wearer’s thoughts without requiring surgery.

“It allows me the opportunity to not think about the process of walking, but think about the destination,” Karpowicz said.

Karpowicz was 27 and working in England when he hit a truck on his motorcycle. After seven days of trying to salvage his right leg, the doctors had to remove it.

“A leg is not a heart, a leg isn’t a soul, it’s not what makes you, you. It was a lot easier to getting back to being a sculptor” once I understood that, he said.

His first prosthetic was just a piece of leather surrounding two rigid pieces of steel attached to a piece of wood.

Now, he has worn his first bionic limb — a leg with a motorized knee and ankle that uses electrodes in contact with Karpowicz’s skin to read signals from his leg muscles — to walk and climb stairs smoothly.

Institute researchers announced the leg’s creation and the results of an initial trial in a study published Tuesday in the Journal of the American Medical Association.

Bionic limbs are not a new concept. The Rehab Institute unveiled what they called the first thought-controlled bionic leg in September 2013. That limb required the wearer to undergo “targeted muscle reinnervation” surgery to help the leg communicate with the wearer’s brain.

But with the creation of a leg that doesn’t require the surgery, thought-controlled prosthetics become a possibility for people who lost their legs decades ago, like Karpowicz, according to project leader Levi Hargrove, director of the Neural Engineering for Prosthetics and Orthotics Laboratory at the Rehab Institute. He said the surgery is normally done within five years of the amputation.

The new limb uses electrodes on the amputees’ skin in place of the surgically altered nerves. All the wearer needs to do is put it on, and the electrodes on the leg will be in place, Hargrove said.

“People just think about moving or walking, we place electrodes over the muscle they have remaining and use algorithms to figure out what the muscles tell the prosthesis to do,” Hargrove said. “We teach the limb how to respond in an initial session. After that, the computer on the leg will respond when it is told to.”

The leg is meant for everyday activities in a broad spectrum of amputees, Hargrove said. Specialized limbs are still needed to swim or run.

Hargrove, an electrical engineer, heads a team of doctors, physical therapists, engineers, graduate students and prosthetists who design, build and test the limbs. The group is now recruiting a group of 15 amputees to try the limbs at home. Hargrove expects the limb to be available for public purchase within four years.

For the majority of amputees in this country, the improved technology could make a big difference. Ten times as many people have suffered lower limb amputations than upper limb, Hargrove said.

They could be people who lose their limbs due to problems stemming from obesity or diabetes, motor vehicle accidents or while serving in the armed forces.

The Rehab Institute’s initial research was sponsored by the U.S. Army, Hargrove said. The sponsorship will continue through the home trial, which will include some veterans who are amputees.

The National Institutes of Health is helping to improve the design of the limb so it learns more about its wearer with every step it takes, Hargrove said.

In the meantime, Karpowicz hopes to eventually use it on a daily basis.

“We are going to teach it to dance, maybe jog a little bit . . . those are some of the things I’d like it to do,” he said. “There’s a lot of things I dream about.”

Sculptor Terry Karpowicz, 67, works in his Bridgeport sculpture yard while wearing the new thought-controlled bionic limb designed by the Rehabilitation Institute of Chicago. | Rehabilitation Institute photo by Sheila Burt

Sculptor Terry Karpowicz, 67, works in his Bridgeport sculpture yard while wearing the new thought-controlled bionic limb designed by the Rehabilitation Institute of Chicago. | Rehabilitation Institute photo by Sheila Burt