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Background on Groundbreaking Orthopedic Surgery

Cassidy, a three-legged German shepherd mix owned by Steve and Susan Posovsky, has become a medical pioneer after being fitted with a prosthetic limb that was created through a process that could one day benefit humans who lose limbs through accidents or disease.

Cassidy’s care team involved Dr. Denis Marcellin-Little, associate professor of orthopedics in the College of Veterinary Medicine, and Dr. Ola Harrysson, associate professor of industrial and systems engineering in the College of Engineering. The two NC State University faculty 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.

Drs. 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. The procedure, which involves 3-D computer modeling, also has been employed to provide Pez, a Beagle with a large hole in the roof of his mouth, with a titanium plate and Mr. Franz, a feline without hind legs, with a prosthetic limb and foot.

Computed tomography (CT) scans help engineers create three-dimensional computer images and then the physical models. Surgeons then use the models to practice the procedure, making minute adjustments to ensure a perfect fit before the actual surgery.

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

"The implications for this procedure are huge," Dr. 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."

Cassidy’s surgery was reported throughout the U.S. and numerous other countries. Here are a few links to that coverage.

  • Link to MSNBC story
    Pioneering implant to get dog back on all fours View article
  • Link to News & Observer story (includes photo gallery and audio clip)
    Rescued dog blazes a surgical trail
    View article
  • Link to NBC-17 story (includes video)
    Implant surgery will put dog back on all fours
    (Link is no longer available at
  • Link to News 14 Carolina story (includes video)
    NCSU gives dog new way to walk
    View article
  • Link to NC State news release
    Groundbreaking surgical procedure will allow dog with amputated limb to walk on four legs again View release

Posted on August 1, 2008