Prosthesis Method May Brighten Future for Amputees
Udo Rehberg walks quickly around the room. He's amuscular man, his stride brisk. With his pant leg rolled down, you'd never know his lower leg is attached to his upper leg with a titanium bolt and other innovations that together form an "osseointegrated" artificial leg.
Osseointegration means the prosthesis is hooked on using a bolt driven intobone, which will grow around it, a living attachment.
That type of prosthesis is believed to offer a brighter future for warriors returning from modern-day battles in the Middle East, for the increasing number of people who are losing limbs to diabetes and accidents and cancers. But the operative word is "future."
There are powerful barriers that must be overcome before osseointegrated prostheses become standard in this country, says Dr. Roy Bloebaum, Ph.D., research professor in the University of Utah Department of Orthopaedics and co-director of the Bone and Joint Research Lab in the Department of Veterans Affairs, Salt Lake City. The U. and VA are working to make it a reality, funded by three defense-related federal grants.
Their targets are preventing the serious infections that have thus far plagued the "built-in" limbs, and improving the design of those limbs.
"We're all interested in making the technology mature enough and safe enough to be introduced in the United States," says Bloebaum of osseointegrated limbs already being tried inhumans in Europe. There are groups in Sweden, Germany and England each doing testing and developing, and the Utah researchers have been consulting all ofthem for their own work. This week, Dr. Horst Aschoff of Germany was featured in Grand Rounds at the U., where his patient, Rehberg, demonstrated his leg. And the U. plans to exchange graduate students with England's group soon.
Aschoff, an amputation specialist atthe Sana Clinics Lubeck, says his program has 29 patients who have received osseointegrated prostheses. But because of infection, they've had to remove theimplants or replace them in many of the patients. Barring the infections, though, proponents say osseointegrated prostheses seem to offer several advantages, including use by those who have lost too much leg to be good candidates for a standard socket attachment, better perception of terrain, lighter weight, increased mobility, better gait performance and more.
When Rehberg was asked if there is anything he could do with a socket prosthetic that he can't do now, he grinnedand said, "No."
Those advantages are driving efforts to solve the problems.
There's no question, Bloebaum says, that American researchers can attach aprosthesis to existing bone and get it to stay there. The battle is inpreventing infection, which has been a very serious problem with osseointegration. "When the skin seal is broken, there's a potential to get infection around that skin area," he says. Soft tissue infections are tough. But infection that gets into bone is particularly difficult to combat.
There are "10 to the 10th power —that's 10 zeroes" cells in the human body. There are "10 to the 13th power bacteria on your skin right now," he explains. The human mouth alone has 600 types. So the researchers have been looking at various antimicrobialdermal barriers, inspired by those that seem to protect hippos from the scary bacteria lurking in their slime pits, even when they cut each other upfighting. They're looking for something that would provide the same protection to humans around the area where the skin has been breached for a prosthesis.
They believe that will likely need tobe combined with some kind of skin immobilization to prevent the breaches, and they're working on that, too.
Finally, they're looking at improved designs, as well, Bloebaum said.
Several members of the research team bare themselves veterans. They take the needs of the injured troops very seriously, Bloebaum says. "I think we'll get there."
But he admits the project, which the military originally estimated would take about three years, stretches still afew years into the future. "We've been humbled by bacteria," he says.
By Lois M. Collins
Deseret News
Published: April 18, 2008
Pictures above: Top: Udo Rehberg of Germany demonstrates his prosthetic leg, which is "osseointegrated,"meaning it's attached to his bone. (Elizabeth Banuelos-Totman)Bottom: Udo Rehberg of Germany demonstrates his prosthetic leg, which is "osseointegrated,"meaning it's attached to his bone. (Elizabeth Banuelos-Totman)
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