Talking to Kirk Billingsley, you get the idea he’s not one to complain. In 2009, he lost a leg below the knee following surgery for an aortic aneurysm, a weakening of the artery that sends blood to every part of the body. But, he did what he had to do to return to his busy job, and he also got back on skis.

“I’m not as good as I used to be, but I’m pretty darn good,” said the now 59-year-old Jackson resident. “That was hard, but I did it.” Still, he was traveling a lot for work, and in time, he found wearing his prosthesis nearly unbearable.

With a standard socket prosthesis, the residual limb rests in what is essentially a hard bucket, which links to a prosthetic knee, limb, ankle and foot. Some patients cannot tolerate this system.

“If the residual limb is soft and fleshy, there’s not much of a muscular component, and pressure on the residual femur and skin irritation can make it hard for people to walk,” said David Del Toro, MD, physical medicine and rehabilitation physician and Medical College of Wisconsin faculty member.


Eager to find relief, Kirk began to investigate osseointegration, a procedure in which a metal implant is inserted into the bone of a residual limb and a prosthesis is then attached. The benefits of the system include increased range of motion and better mobility, as well as the elimination of recurrent discomfort.

For years, individuals had to travel to Australia or Sweden to take advantage of the new technique. So when Kirk learned that Froedtert Hospital, the academic medical center of the Froedtert & MCW health network, had begun offering OPRA,™ he contacted Dr. Del Toro, who had worked with him in the past. OPRA stands for Osseointegrated Prostheses for the Rehabilitation of Amputees and is the only implant system approved by the Food and Drug Administration.

As much as he wanted to improve the quality of his life, Kirk acknowledged that moving ahead gave him pause.

“You will have a piece of metal sticking out of the bottom of your leg for the rest of your life, not a knee replacement covered with tendons, skin and muscle,” he said.

After a consultation with John Neilson, MD, orthopaedic surgeon and MCW faculty member, Kirk had the first of two surgeries in October 2020. In the initial operation, Dr. Neilson implanted a titanium fixture in the femur. Over the following months, the bone grew around this fixture to anchor it. In the second procedure, which Kirk had in December, the abutment was installed. It extends outside the skin and attaches to the prosthesis.

“Froedtert Hospital is the only hospital in Wisconsin that offers this,” said Dr. Neilson, who learned the approach directly from its inventor, Swedish orthopaedic surgeon Rickard Brånemark. “We want to be able to provide this option for amputees whenever possible. It’s really a great opportunity to have better function.”

Adjusting to a New System

Adapting to an osseointegrated system demands a lot of the user.

“With longtime above-the-knee amputees, the bone actually becomes osteoporotic because patients are not bearing weight through the leg, but through the ischium, in the hip,” Dr. Neilson said. “When you move to an OPRA device, your bones are quite weak and are at risk for breaking. We begin patients on a weight-bearing protocol, where they slowly increase the amount of weight they place on their residual limb.”

While Kirk chose to do most of that training at home, he worked closely with Elizabeth Schmidt, DPT, a physical therapist at Froedtert & MCW West Bend Health Center, who had been oriented to the new system by Dr. Del Toro.

“Normally, once a patient gets the prosthesis, they can start to gradually put weight on their leg and begin to walk,” she said. “But in this instance, allowing the bone to take the impact of the weight takes a lot longer.”

“For eight months, everyday activities like taking a walk or going to the store are paused,” Kirk said. “You have to make the best of it and remember the long-term goal — getting back to where you can go out without having to stop because it hurts too much. People like me, in this situation, we chase that dream until we find some resolution. Hopefully, I’m done chasing.”

“I fully expect Kirk to be an enthusiastic advocate for this type of prosthesis,” Dr. Del Toro said. “He is so excited to do this and is very motivated. More importantly, he will be more mobile and that will be great for him and for other people to see.”