Cyrano, a cancer-surviving 10-year-old cat, is back home in Upperville, Va. following the success of a total knee replacement surgery — the first-of-its-kind for a feline — at North Carolina State University’s Randall B. Terry, Jr. Companion Animal Veterinary Medical Center.
Cyrano was standing on his leg within a day of the operation but will need to rest for about a week. Owner Sandy Lerner will need to restrict Cyrano’s activities for three months before the cat, that weighs some 20 pounds, will be allowed to resume full, unsupervised activity.
Dr. Denis Marcellin-Little, professor of orthopedics at the NC State University College of Veterinary Medicine, led a team of four other surgeons in the nearly six-hour surgery on Jan. 26 to replace the knee on Cyrano’s hind leg. As in sophisticated human knee replacement, Cyrano’s state-of-the-art knee will provide a full range of natural motion unavailable in previous feline knee replacement surgeries.
The NC State University surgery is considered unique because the replacement prosthetic knee was engineered and custom-made for Cyrano and implanted through a technique that fuses engineered components into the leg. The process, called osseointegration, creates a strong, permanent bond between living bone and the titanium implant that is anchored into the bone—similar to the way an artificial tooth is anchored into the jaw.
The procedure culminated eight months of collaboration involving high tech 3-D computer design, unique component engineering, complex manufacturing, and technical surgery skills that required contributions from veterinarians and engineers from around the U.S. and abroad. Polymer replicas of Cyrano’s leg created by computer modeling at the NC State University College of Engineering allowed Dr. Marcellin-Little to practice the surgery over a period of time and suggest delicate changes in the engineered components. The minute size of the intricate components increased the complexity of the design, engineering, and fabrication of the knee joint and the components which extend into the bone on both sides of the prosthetic knee.
Cyrano’s knee was weakened following radiation therapy to treat cancer and while the cancer is in total remission, the cat could not stand on the painful leg. Owner Sandy Lerner’s search for options to amputation that she believed would negatively affect the active cat’s quality of life brought her to NC State where Dr. Marcellin-Little and Dr. Ola Harrysson, a professor of industrial and systems engineering in the College of Engineering, pioneered osseointegrated implants and customized prosthetic limbs in 2005.
Dr. Marcellin-Little during the nearly six-hour surgery to provide Cyrano with a custom-made, osseointegrated prosthetic knee–the first surgery of its kind for a cat. AP photo by Allen Breed.
Scan taken after Cyrano’s surgery show the custom-made, osseointegrated prosthetic knee implanted in Cyrano’s leg. Note extension into the live bone on either side of the prosthetic knee.
In the osseointegrated procedure, the live bone continues to grow into the implant. This allows the prosthesis and bone to become a single, solid unit. Human medicine is interested in the technique and its application for people who have lost limbs to disease, accident, or combat.