- Associated Press - Sunday, January 29, 2012

RALEIGH, N.C. — Because Cyrano weighs more than 20 pounds, amputating his cancer-weakened leg was out of the question. So the tubby tabby’s owners turned to doctors and engineers at North Carolina State University to get him back into mice-catching trim.

On Thursday, the 10-year-old cat from Upperville, Va., received what doctors think is the first feline total knee replacement in the U.S.

“This is the most complex implant that N.C. State has made and really, in all honesty, that anyone has built for any situation that I know of,” said surgeon Denis Marcellin-Little, a French-born veterinarian.

Cyrano - his full name is Mr. Cyrano L. Catte II - underwent treatment last year at Colorado State University for cancer in his left hind leg. The disease is in remission, but the treatment left the leg nearly useless and extremely painful.

Mr. Marcellin-Little and N.C. State engineer Ola Harrysson are pioneers in osseointegration, a process that fuses a prosthetic limb with living bone. In 2005, Mr. Marcellin-Little performed the world’s first surgery to fuse leg implants with a cat’s bone tissue, so Cyrano’s owners turned to him for help.

Britain’s Noel Fitzpatrick was credited with the world’s first total knee replacement in 2009 on a cat named Missy, whose leg was crushed by a car. But Mr. Marcellin-Little said Cyrano’s plastic and cobalt chromium alloy implant is more like those used in humans.

“It has a form of articulation that is unique - that allows the implant to bend and rotate,” he said, demonstrating with a model during a news conference the day before the surgery. “The devil is in the details.”

Such implants have become common in dogs. But a cat’s smaller anatomy has proved more difficult to work with, and Cyrano’s damaged bones posed an additional challenge, Mr. Marcellin-Little said.

Unlike other joints, which are machined, Cyrano’s knee - in cats, it’s called a “stifle” - was fabricated using a laser process that hardens metal powder to exactly replicate his bones. More than a dozen people worked on developing and testing the implant, each half of which is about 2 inches long.

Thursday’s operation began around 10:30 a.m. Attendants did not wheel Cyrano to the intensive care unit until almost 5 p.m.

Mr. Marcellin-Little said the tabby’s girth and big bones were a plus. He said Cyrano should be up and around in about a week, though he won’t be climbing trees for a while yet.

“We would like him to take it easy for about three months after surgery,” the doctor said. “And then we will let him be himself.”

Because so much of the time and material were donated, university representatives could not give a total cost estimate.

The bill to owners Sandra Lerner and Len Bosack will be around $20,000. Sitting in a waiting room after the surgery, a visibly exhausted Ms. Lerner, who helped found electronics giant Cisco Systems, said “Rat Boy” is worth every penny.