NCSU veterinarian uses osseointegration to rebuild limbs

RALEIGH, N.C.— In a first-of-its-kind procedure, osseointegration was used in a 1-year-old cat born without the lower half of its tibias at North Carolina State University (NCSU) College of Veterinary Medicine.

Osseointegration incorporates prosthesis with bone, making the two components one unit after approximately four to six weeks when the bone integrates with the metal implant.

The shaft of the artificial limb is inserted into the patient's bone and anchored in place. Once the living tissue and prosthesis mesh, the patient has a permanent prosthesis — eliminating the need for potentially removable prosthetics that can irritate skin.

Technician Wendy Brackett comforts George Bailey after his surgery at North Carolina State University, College of Veterinary Medicine.

The approximately $35,000 project was the combined effort of veterinarians, undergraduate students and researchers at the university's College of Engineering.

The procedure hasn't been performed at this level on a cat, says Dr. Denis Marcellin-Little, associate professor of orthopedics at the university. Marcellin-Little specializes in total hip replacement, external fixation, treatment of bone deformities and physical therapy and was the surgeon for the cat.

"Once the procedure becomes more common, the cost will be greatly reduced," Marcellin-Little says. "Much of the cost went into engineering and design of the prosthesis. The surgery is comparable to a total hip replacement that would range in price from $2,000 to $3,000."

A custom-made implant was attached to the cat's tibia, which is about half the size of a pencil.

A foot will be added after the bone and implant have stabilized, making the permanent structure more functional.

Drs. Marcellin-Little and Matt Stepnik attach the prosthesis to the upper tibia.

"It will be difficult enough for the cat to learn how to walk on three legs, so for now, just one leg will be attached," says Marcellin-Little.

The surgery was a combined effort using modern medicine and technology, Marcellin-Little says. First, CT scans were taken of the cat and given to two engineering students, who were responsible for designing the functionality of the device. The prosthesis was created using bio modeling and composed of plastic for a trial run.

Rapid prototyping allowed Marcellin-Little, to perfect the insertion and fixation of the prosthesis to the bone.

"The surgery had been planned for months," Marcellin-Little says. "This could have a significant impact in the animal world and in humans. There are very few people who have undergone the procedure, and all were overseas."

The completed surgery displays the connection before closing.

The final prosthetic leg and foot were composed of lightweight, biocompatible metal made by the university's Department of Industrial Engineering and an outside company, Marcellin-Little says.

The idea behind the procedure was derived from wanting to improve animal's quality of life.

"In the future if this proves to be a success, the procedure would be helpful with a variety of companion animals when they have limbs removed due to trauma or cancer," Marcellin-Little says. "The next step is to reproduce the procedure in a dog, then a front leg of a dog or cat."

The procedure is similar to the way an artificial tooth is anchored into the jaw, he adds. There was some concern with the bone splitting in this procedure.

"Luckily the bone held up, and everything went very well," Marcellin-Little says. "Within a month, the bone will begin to grow into the porous-part of the implant; that is when the foot will be attached to the prosthesis."

Without the surgery, the cat would eventually develop problems with his hips, lacking a way to balance his weight for the lower half of his body.

The cat returned home to its owners the day after the surgery. Physical therapy will not begin until the wound and bone graft has have time to heal and become stronger.

Gait training will come after new radiographs have been examined and the foot has been added to the prosthesis, the doctor says.

"I see a great future for not only animals, but people too using this procedure," Marcellin-Little says. "Diabetic patients that are missing digits or a foot could benefit."

There are other pet owners interested in having this procedure performed on their pets; however, there are none scheduled to be performed at presstime.