A Better Life For Soldier-Amputees: U of U, WPI Researchers Developing 'Intelligent' Artificial Limb Implant

August 17th, 2010

(PhysOrg.com) -- As unprecedented numbers of U.S. soldiers return from the wars in Iraq and Afghanistan missing arms, legs, hands, and feet, many come home to lives of greatly reduced mobility and fulfillment because poorly fitted artificial limbs cause infections or are too painful to wear.

Scientists from the University of Utah Department of Orthopaedics and Worcester Polytechnic Institute (Worcester, Mass.) believe soldiers who've made such sacrifices deserve better. To help make that happen, researchers at the two institutions plan to use a $3 million Department of Defense appropriation to design an "intelligent" prosthetic implant that will make artificial limbs comfortable to wear and infection-free by attaching internally to the skeleton and employing a skin seal to prevent bacteria from entering the attachment site.

The appropriation, secured with the leadership of Utah Sen. Bob Bennett, will help both the U of U and WPI continue their respective research in a new collaborative framework, according to Charles L. Saltzman, M.D., Utah co-principal investigator on the project and professor and chair of orthopedics at the U of U School of Medicine. The researchers plan to have an implant design ready for clinical trials within five years.

"This funding is going to allow us to support high-payoff research that will deliver significantly improved quality of life for the young men and women who have made extreme sacrifices in Iraq, Afghanistan, and elsewhere," Saltzman said. "We believe it is our responsibility as a society to ensure that the utmost is done to heal them."

Roy D. Bloebaum, Ph.D., director of the Bone and Joint Research Laboratory at the Veterans Affairs Salt Lake City Health System, research professor and Albert and Margaret Hofmann Chair in Orthopaedic Surgery at the University, and J. Peter Beck, M.D., adjunct professor of orthopedics at the U of U, are also Utah co-investigators on the project. W. Grant McGimpsey, Ph.D., professor and director of the WPI Bioengineering Institute, and Christopher Lambert, Ph.D., research associate professor of bioengineering, are the co-principal investigators at WPI.

"There are many significant challenges we must overcome to bring this technology out of the lab and into the clinic. The collaboration between our two institutions has all of the elements necessary to achieve this goal, from basic science and engineering to clinical expertise. I am very pleased we are moving ahead on this research and that we have such a productive partnership," said McGimpsey.

The need for a new prosthetic implant arises in large part from the increased survival of soldiers in battle. The body armor that protects a soldier's torso from bomb and missile blasts has, along with advanced battlefield medicine, decreased mortality from injuries. But body armor does not protect arms and legs, leaving soldiers exposed to severe limb injuries that often require amputation.

These types of amputations often leave a short stump where the arm or leg was taken off, making it difficult, if not impossible, to fit a conventional prosthesis that is comfortable and functional. In these cases, the artificial limb also often causes skin to break down and becomes infected at the attachment site.

The pain and infection related to a poorly fitted prosthesis can force the wearer to discard an artificial limb altogether. It's estimated, for example, that upward of 70 percent of patients with artificial arms will discard their prostheses because of pain, infection or both, according to Bloebaum.

University of Utah and WPI investigators are addressing these problems in two ways.

First, they're designing a titanium alloy implant that will attach inside the bone above where an arm or leg has been amputated. The implant will serve as a base for attaching an artificial arm, leg, hand or foot to the stump, taking the weight off of the stump and placing it on the implant and the bone. This will allow artificial limbs to fit better and eliminate the pain that affects so many soldiers and others who discard prosthetics.

Second, to prevent infection, researchers headed by Bloebaum are working on a way to make skin heal around the implant in a way that stops infections. "Without an impermeable seal, bacteria can go right down the implant post," Bloebaum said. "Our goal is to learn how to make skin heal in a way that creates a permanent seal to stop bacteria from getting into the implant site and creating infections."

Provided by University of Utah