The Iowa Stater
February 2002
Big bird becomes a model
When it comes to intra-state sports rivalries, loyalties are divided between the two colorful birds, Cy and Herky, that serve as school mascots for the Cyclones and Hawkeyes. But when it comes to biomedical research, specialists from both schools have no trouble agreeing on the value of a different bird -- the ostrich-like emu.Biomedical researchers at Iowa State's College of Veterinary Medicine and the University of Iowa's College of Medicine used emus to develop a new animal model to study a disease that causes mechanical collapse in the human hip.
The disease, femoral head osteonecrosis, afflicts 20,000 to 30,000 new patients each year. Most are young, in their 30s or 40s, as was Bo Jackson, a Heisman Trophy winner whose professional sports career was ended by the disease. Osteonecrosis occurs when blood flow to the hipbone becomes abnormal and the bone dies. As the disease progresses, the head in the hip socket collapses and must be replaced by an artificial joint.
Unlike hip replacements for older people with arthritis-caused deterioration, the artificial joints for osteonecrosis patients have a lower success rate and last a much shorter time. (Bo Jackson has worn through several artificial joints). In their quest to find a more effective treatment strategy, medical researchers have been stymied by the lack of an animal model that reliably mimics the natural course of the disease in humans.
Enter orthopedic specialist Michael Conzemius, an ISU associate professor of veterinary clinical sciences with a Ph.D. in biomedical engineering. Two years ago, he developed a unique elbow implant that allows dogs to receive a total elbow replacement -- a medical feat that was unsuccessful using earlier implant devices.
With that patented success completed, Conzemius was open to an idea presented by Thomas Brown, a U of I professor and one of the leading experts in orthopedic biomechanics. Brown postulated that an emu might provide an effective research model because it is a two-legged animal with a high activity level and a hip structure similar to humans.
Linking that concept with experts in both human and veterinary orthopedics resulted in a $2.6 million grant from the National Institutes of Health. So far, the study has demonstrated that it is possible to closely replicate the stages of osteonecrosis from early onset to the end-stage mechanical collapse of the femoral head.
"We're pleased with our progress, and we believe that our bipedal model provides much more information than could previously be gathered using four-legged models," Conzemius explained.
Emus are 5 to 6 feet tall and weigh 90 to 120 pounds. With powerful legs, they are quick and agile, defying their gawky appearance. To replicate the dying of bone in the human hip, Conzemius' team uses a combination of relatively noninvasive surgical and medical procedures to injure the bird's hip, and then monitors the development of lameness over a period of up to six months.
The animal model developed by Conzemius led to computer modeling conducted by researchers at the University of Iowa. Both approaches provide valuable information and have gained the attention of additional orthopedic researchers. Investigators from the Mayo Medical Center and Johns Hopkins University are partners with Conzemius and Brown in a second osteonecrosis study. Researchers from all four institutions spent a weekend in August at ISU's College of Veterinary Medicine to get a hands-on look at the emus that are contributing to the study.
The new studies focus on treatment strategies. Researchers want to find out what causes the interference of blood flow to the femoral head and examine the effectiveness of intervention strategies that might prevent the interference.
-- Phyllis Peters
College of Veterinary Medicine
 Wanda Gordon and Michael Conzemius prepare an anesthetized emu for a diagnostic procedure using a new CT Scanner in the ISU Veterinary Teaching Hospital. The equipment allows radiologists to capture and reconstruct three-dimensional views in a noninvasive manner. Photo by Jim Fosse. |