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August 5, 2008

Engineers help give dog a new leg

  — from NC State News Services

The dog, Cassidy, and his owner, Steve Posovsky, before the groundbreaking surgery. (Photo: Philip Ruckart)

A pioneering North Carolina State University collaboration between a veterinary surgeon and an engineer is giving a deserving dog the ability to walk on four legs again.

Cassidy, a male German shepherd mix, was born with a defect in his right hind leg. His owner was referred to NC State's College of Veterinary Medicine in 2005 in order to have the defective limb removed. Three years later, Cassidy came back, this time for surgery that replaced the lost leg with an osseointegrated prosthetic implant.

Dr. Ola Harrysson, associate professor of industrial and systems engineering, and Dr. Denis Marcellin-Little, associate professor of orthopedics, are pioneers in the area of osseointegration, a process that fuses a prosthetic limb with an animal's (or human's) bones. The result is a custom-designed, limb-sparing prosthesis that behaves more like a natural limb - and a technique with implications for the future of human prosthetics.

Surgeons sew up the skin around the implant. They'll attach a prosthetic limb in a few months. (Photo: Philip Ruckart)

Surgeons performed the procedure on July 31, inserting a titanium implant into the dog's leg. Cassidy will return to Raleigh in a few months to have the rest of the prosthesis attached to the implant, which now protrudes like a knob from his leg.

Marcellin-Little and Harrysson began their work on osseointegrated pet prosthetics in 2005 with a cat named George Bailey, who had been born without the lower half of his hind legs. Harrysson designed and built the limb in collaboration with his students and Marcellin-Little, who performed the surgery. The procedure involved inserting a titanium nail into one of the legs and securing it with screws.

Since then, the collaborators have improved and strengthened the design, and Cassidy's limb surgery was the third of its kind -- and the first such surgery on a dog --  performed at NC State.

"This research collaboration, along with new technologies, has made it possible for us to custom design and directly fabricate metal prosthetic implants in a timely and economical fashion," Harrysson says. "Ten years ago this process would have taken much longer, cost much more and not been as accurate. We see this process becoming even faster and more cost-effective in the future."

The researchers hope that Cassidy won't be the sole beneficiary of this surgery.

"The implications for this procedure are huge," Marcellin-Little says. "As we gain more experience with the surgical technique and the design of the limbs, we see the possible benefits for humans - implants that allow the prosthetic limbs to attach without chafing or irritation, and limbs with more natural ranges of motion. We believe that this is the future of prosthetics."

- peake -



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