ShareThisEven the guys whose scalpels and engineering wizardry had turned a three-legged dog into a four-legged one had to stare.
Cassidy, a German shepherd mix and former stray, took a few tentative steps this week on his new carbon fiber and titanium limb, then he made a break for it. He wandered down a hall at the North Carolina State University College of Veterinary Medicine with his buddy Della, a lumbering Rhodesian ridgeback.
"I'm actually a little bit shocked," said orthopedic surgeon Denis Marcellin-Little as he and Ola Harrysson, an associate engineering professor, studied Cassidy's gait and newly level pelvis. "We're 10 minutes into it, and he's moving really well." Cassidy is a celebrity wherever he goes, even to people who don't know that he's the first dog in the country to get a custom artificial limb fused directly to the leg bone.
NCSU has performed similar operations on a pair of cats and has two more dogs scheduled in coming weeks. Researchers intend to use what they're learning to help human amputees.
The NCSU researchers hope to transfer some of what they've learned to human patients in a few years. The Department of Defense is interested in studying possible applications for troops injured in Iraq and Afghanistan.
About 150 humans have undergone a basic form of the operation in Sweden. But researchers hope to take the idea a step further by making custom fittings, and by having the bone attach itself, which could reduce failures at the attachment point. They also hope to parlay their expertise into a new center that focuses on this crossroads between medicine and engineering.
In Cassidy's case, Marcellin-Little attached a custom-made titanium socket to his right rear tibia last summer, and, by this week, X-rays showed the bone was growing firmly into the honeycombed metal. Cassidy had been stumping along since fall on a simple, pogo-stick-like metal "training leg" but was ready for the final, space-age version to be screwed into the socket.
The dog's owners, Steve and Susan Posovsky, of Delray Beach, Fla., have no idea how Cassidy lost his leg -- it was gone when they adopted him. He also is in remission from cancer and still sports several shaved patches from his continuing chemotherapy.
After Cassidy was fitted with the final design this week at the vet school, he, Della and the Posovskys hopped into their truck to visit the engineering lab where Tim Horn, a Ph.D. candidate who made the carbon leg, could make some adjustments.
Harrysson and some of his students have been feeding CT scans from the vet school into a computer program. Then an array of machines uses the data to craft replicas of patients' bones in hard plastic. They also make metal patches and fittings that conform perfectly to the outside of the bones, like Cassidy's fitting.
The veterinarians can use the plastic bones to study how to perform a tricky operation, and then actually practice it by cutting and drilling the plastic, settling on just the right techniques and tools before mistakes get serious.
The collaboration started in 2002, when Marcellin-Little called Harrysson. Marcellin-Little had a patient, a German shepherd, with such severely deformed hind legs that it couldn't walk. Marcellin-Little wondered whether Harrysson would make models of the bones so that he could figure out how to fix them. After the operation, the dog was able to run and jump again and lived five years more, Harrysson said.
E-mail Jay Price at jay.price(at) newsobserver.com
(Distributed by Scripps Howard News Service, www.scrippsnews.com.)
Must credit The News and Observer of Raleigh, N.C.
