Engineering healing

By Website Administrator | Jan 9, 2009

With research funded by the federal government, a Kettering professor is working with orthopedic surgeons to improve healing of serious lower leg injuries for soldiers and civilians alike.

Injuries to the lower leg, including trauma caused in battle, in an automobile accident, from a gunshot wound or other trauma, have historically proven difficult for doctors to treat. Dr. Patrick Atkinson, professor of Mechanical Engineering at Kettering University, is working with orthopedic surgeons at McLaren Regional Medical Center to develop more effective treatment for this type of injury.

They have focused their research on stabilizing the lower leg during the healing process. “We had to simulate a big injury, similar to a fracture caused by a bullet striking bone,” said Atkinson, “not necessarily what we would see in the United States, but more from a large caliber gunshot wound occurring far away from a hospital in a challenging environment.”  

Such wounds tend to have large bone and soft tissue defects mixed with mud and dirt causing there to be a high risk of infection, according to Atkinson. Military situations may also include a long trip to medical care. All of these factors are major issues contributing to the difficulty of getting bone to heal and an elevated risk of infection, he explained. “They make treatment challenging,” Atkinson said.

It is just this challenge Atkinson and Dr. Casey Beran, M.D., McLaren Regional Medical Center and Hurley Medical Center, Orthopedic Surgery resident, and Vineetha Gheebarughese, of LakeOrion, a Kettering graduate student, are working to address.

In total, four entities are involved in the research project, Kettering University, Michigan Technological University, Mott Community College (MCC) and the Southwest Research Institute (SWRI) in San Antonio. “We’re leveraging our resources to solve the problem,” said Atkinson.

“Traditionally there are two ways to treat severe injuries to the lower extremities,” said Atkinson. “One method is to amputate the lower leg, which is easier on the patient overall,” he said.  It takes an amputation patient about one month to then be fitted for a prosthetic and rehabilitate to become ambulatory more quickly, explained Atkinson.  The negative aspect of amputation is that the person is missing a part of their body.

Severe wounds to the lower leg present a variety of challenges, including less soft tissue to cover, hydrate, and deliver blood to the wound area, making it harder to promote healing in the shin bone. In a thigh injury there is generally more soft tissue available to promote healing.

Additionally, often salvage of a lower leg requires multiple surgeries, perhaps six to seven surgeries over a period of two years, he said, and there is a chance the surgeries will not work and the leg will still have to be amputated.

“Studies have shown that after two years, both amputees and patients whose legs were salvaged were equally pleased/displeased with the outcome,” said Atkinson. “Our research is trying to tip patient satisfaction in favor of the salvage because we think that is what patients want.”

“Our goal is to create a technology to convince surgeons and patients to choose salvage and tilt the odds in favor of success for the salvaged leg,” Dr. Casey Beran.

“We have developed a treatment to improve healing in these cases,” Atkinson added.

The technology they are utilizing has been around since WWII, according to Atkinson. It involves inserting rods down the length of the bone to stabilize the site during healing. Because bones are hollow, the rod stabilizes the leg until the bone can re-grow.

“In the case of a gunshot wound where a piece of bone is missing, we have to fill the gap with bone stimulating drugs suspended in a gel that turn on the bone building cells to build a bridge between the two ends,” explained Atkinson.

Atkinson likens the process to a constructions site. “The gel acts like the girders in a building; the bone stimulating drugs then move along the girders, building the structure as they progress.  Additional plastic surgery on the muscle flap provides blood and a healthy environment for the workmen to work in.”

The main issue Atkinson and his team are dealing with is that the metal rods can wear out before the wound can heal. “It is a footrace to get the bone to heal in an effort to protect the rod.”

Typically a leg in this condition is not weight bearing. Currently surgeons can only estimate load bearing ability on the bone versus the rod, based on how the bone looks on X-ray. To develop a better system, the Ketterin gteam measures the stress on the rod to indicate how much load the leg with the rod could carry.

“We hope to see the stress on the rod go down as the bone grows and takes on more load.”

The first part of their clinical testing will involve surgery simulation on cadaver rabbit legs (supplied by a butcher). “Kettering University and McLaren Regional Medical Center’s Orthopedic Surgery residency program have engineered a bunny-sized rod for testing. We will be working with local orthopedic surgeons to make sure our small scale rabbit surgeries will eventually translate to a larger human-sized scale,” Atkinson said.

“Can the design carry the load to facilitate daily activities? The stress load tests are done on a small scale, but theoretically, when translated to a larger ratio, the rod should continue to carry the load without failure,” he said.

The research has already proven the team’s rod design is mechanically appropriate. Versions of this type of treatment are currently offered to patients at Hurley Medical Center and McLaren Regional Medical Center in Flint.

“What we are focused on is making salvaging a limb more successful in military and trauma situations,” explained Atkinson. “Specifically in military situations we want to develop a technology for an initial field hospital surgery to be followed by a second surgery in a larger medical facility.”

In addition to the military applications, the resulting technology has numerous civilian applications, according to Atkinson.

The four entities involved in the research are dividing up the project to enhance speed of design and testing.  “At Kettering we have been working non-stop since October 2007,” said Atkinson, “it took three years prior to that to get through the review process for the project.” Researchers hope to have initial results by 2009.

For more information about the project, contact Dr. Patrick Atkinson at patkinso@kettering.edu.

Written by Dawn Hibbard
810.762.9865
dhibbard@kettering.edu