Doctors hailed a groundbreaking transplant to replace 80 per cent of a woman's face, saying Wednesday it is a means for the severely disfigured to "face the world" without humiliation.

It was the world's first near-total facial transplant and the fourth known facial transplant to have been successfully performed to date.

"We need the face to face the world," said lead surgeon and researcher Maria Siemionow of the Cleveland Clinic.

"There are so many patients there, in their houses, where they are hiding from the society because they are afraid to walk to the grocery stores. They are afraid to go to the streets, because they're called names, and they are humiliated.

"So we very much hope that for this very special group of patients, there is a hope at one day they will be able to go comfortably from their houses and enjoy the things which we take for granted."

Doctors released few details about the patient, save to say that she had been disfigured to the point where she could not eat or breathe on her own as a result of a traumatic injury several years ago which left her without a nose and palate.

The hospital said the woman, who did not wish to be identified, had exhausted all conventional reconstructive surgery to replace her nose and rebuild her mouth, cheeks and lower eye sockets.

They hoped the operation would allow her to regain her sense of smell and ability to smile and said she had a "clear understanding" of the risks involved, including that her body could reject the new face.

The woman is doing well and showing no signs of rejecting the new face, doctors said.

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.

There are also concerns that the operation could eventually be used for purely cosmetic purposes or as a means of altering someone's identity.

Doctors at the Cleveland Clinic stressed that such operations should be limited to a medical context in order to free severely disfigured people from the suffering associated with social isolation.

"The relief of suffering is at the core of medical ethics, and provides abundant moral justification for this procedure," said the clinic's chair of bioethics Eric Kodish.

"A person who has sustained trauma or other devastation to the face is generally isolated and suffers tremendously. The damage to the quality of life cannot even be put into words."

Leading medical ethicist Arthur Caplan agreed that this suffering was sufficient to "risk possibly killing someone to improve their appearance for a better quality of life".

"If there is nothing else to be done, it actually makes sense for them to take a risk that involves death," Caplan, the director of the centre for bioethics at the University of Pennsylvania, said.

"It's ethically justifiable."

Doctors in France performed the first partial face transplant in 2005 on a 38-year-old woman, Isabelle Dinoire, who was disfigured in 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 French man underwent surgery in 2007. He had a facial tumour called a neurofibroma caused by a genetic disorder.

The tumour 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.

The latest operation was the first facial transplant known to have included bones, along with muscle, skin, blood vessels and nerves.

The woman received a nose, most of the sinuses around the nose, the upper jaw and even some teeth, said Dr. Frank Papay, the clinic's plastic surgery chief.

Doctors paid special attention to maintaining arteries, veins, and nerves, as well as soft tissue and bony structures, as they recovered the donor's facial tissue.

The surgeons then connected facial graft vessels to the patient's blood vessels in order to restore blood circulation in the reconstructed face before connecting arteries, veins and nerves in the 22-hour procedure.

AFP