A team of Ohio doctors have replaced 80 percent of a woman's face in what is considered the world's first nearly complete facial transplant, the Cleveland Clinic announced Tuesday.
It was the first such operation in the United States and the fourth known facial transplant to have been successfully performed to date. The procedure took place in recent weeks on a patient who was disfigured by a traumatic injury.
The hospital released no further information about the patient, whom it said did not wish to be identified.
Facial transplants are controversial because they carry heavy risks and are performed to improve a patient's quality of life rather than as a life-saving operation.
The risks include failure of the transplanted tissue and complications from anti-rejection drugs, which the patient must take for the rest of their life.
Doctors in France performed the first partial face transplant in 2005 on a 38-year-old woman, Isabelle Dinoire, who was disfigured by a dog attack.
In 2006, a Chinese man underwent a facial transplant including the connection of arteries and veins, and repair of the nose, lip and sinuses. A bear had mauled the 30-year-old farmer as he looked for stray sheep.
A 29-year-old man French man underwent surgery in 2007. He had a facial tumor called a neurofibroma caused by a genetic disorder.
The tumor was so massive that the man couldn't eat or speak properly.
The Cleveland Clinic became the first US hospital to approve the procedure four years ago.
Maria Siemionow, director of plastic surgery research at the Clinic, performed the surgery along with a team of seven other doctors, according to Clinic officials.
Siemionow has conducted extensive research transplanting faces and limbs of laboratory rats.
A facial transplant involves the use of donor tissue to repair severe face disfigurement caused by burns, tumors, malformations or trauma, such as car crashes.
More information on the Ohio operation is expected at a Wednesday press conference.