IN ONE CORNER of the operating theatre, the green-gowned surgeon has been sitting quietly for some time, chiselling away at a small sculpture cupped in his hand.

On the other side of the room, his young patient is lying still on the operating table, watched by other doctors as plastic surgeon David Gault sits gouging and filing at what appears to be a piece of white-coloured bone.

As he finishes, he shakes the debris from his sculpture, carefully wipes it clean, and holds it up to the light to check that all is well. As he does so, it becomes clear that the sculpture he has been working on is a delicate human ear.

During the last 50 minutes or so in the middle of a five-hour operation at the Wellington Hospital in London, Dr Gault has turned two or three sections of living rib-bone cartilage taken from the young patient into his new ear.

Over the next two hours, he will fit the ear into a "sock" of skin attached to the sleeping boy's head. Within a few weeks he'll have an ear growing where once there was just a blob of loose skin.

This state-of-the-art surgery is revolutionis- ing the lives and appearances of the hundreds of people who are either born with one ear - a condition known as congenital microtia - or who have suffered trauma, either through car accidents or extreme cases of biting.

Ear reconstruction has held a technical fas- cination for doctors and scientists for decades, and cartilage, which is a kind of human gristle, is the material that surgeons and doctors have been working with most recently.

"Historically, almost everything has been used for ear reconstruction ... platinum, ivory, gold, oxtail, pig tissue, plastic, silicone, titanium, and so on," says Dr Thomas Romo, head of facial plastic surgery at Lennox Hill University Hospital in New York. "The problem with most of these substances is that they are not bio-compatible. A second problem is that the ear is located in a position where trauma occurs very easily, so you need something that is not going to get damaged."

During the first half of the marathon operation that Dr Gault regularly performs at the Welling-ton Hospital, the raw material that will become the new ear is harvested from the patient's chest.

"We take five to six inches of cartilage from between the end of the rib bones and the breast bone and then I turn it into an ear, using tools that were basically designed for sculptors," he says.

"What we need is a piece of the patient's own tissue that we can carve into the exact shape of an ear. Cartilage suits that purpose very well. We could make it out of plastic or pig cartilage, but autologous cartilage gives the best long-term results, with fewer risks of infection or rejection."

By the time the cartilage has been removed, Dr Gault already has a blueprint for the ear, usually based on a drawing he's made of the one good ear, which acts as a template for the other.

"Making it look right is one of our priorities. We are now getting ears that look like ears. If you don't go the full nine yards, they just don't. One of the problems, until relatively recently, was that no one made this field of work their speciality. As a result there are a lot of ears around that look like root vegetables," he says.

With microtia, a condition which affects one in 8,000 children, one ear is usually normal, but in place of the second, there is just a blob of skin the size and shape of a small peanut.

Sculpting complete, what Dr Gault does next in the operation is to insert the ear he has made from still-living tissue into this pocket. Once the skin has been stretched over it, a pump shrink-wraps the skin onto the cartilage. "It's like putting bacon into a vacuum-pack," explains Dr Gault.

"This is the most dramatic part of the operation," he says. "In an instant, what you've been making has been turned into a real ear."

For patients like 11-year-old J who have the operation done, the results are spectacular, both physically and psychologically.

"Until he was five or six he let his hair grow to cover it up and we thought that did the trick," says his father. "But as he got older he became more self-aware and it really began to affect him. He didn't seem to like himself very much, and generally he was a very unhappy little boy with few friends.

"We found out about the operation and it was J himself who decided to have it done. The ear looks excellent and has made a big difference to him. He is far more self-confident and he is very proud of it - one of the first things he did was to have his hair cut short. He is much more outgoing and has a lot more friends. I don't think we realised at the time how upset he was about it."

The operation, which is not usually carried out until a child is six (at which age ears have grown to 90 per cent of their eventual adult size), is also being performed in New York, where Dr Romo is working both with cartilage, and has been experimenting with a new type of polyethylene insert.

He says that in the most typical cases of microtia, the ear canal has bone in it, the ear drum is absent, and the middle ear system is small, but the inner ear is intact. "We first do a special bone hearing test to see if the inner ear is normal. If it is, we track the nerve and a specialist surgeon comes in to drill out an ear canal, make an eardrum, and hook it up to my ear. In that way we can restore the hearing in most cases too," he says.

Although using cartilage is the current state- of-the art method of ear reconstruction, it is not regarded as the final solution and a number of other techniques are at the research stage.

"I've been working with porous polyethylene as a moulded framework which is put inside the skin," says Dr Romo. "It has advantages, one of which is that kids don't need to have a hole made in their chests to take out these ribs. That can carry a high morbidity risk, and you need to take a piece of rib three centimetres by six to make an ear. That's a pretty good hunk out of a child's chest."

Another technique undergoing trials in Scandinavia is a titanium insert in the side of the head to which an artificial ear is attached. That ear is then linked up to a bone-sensitive hearing aid.

But most promising of all is a procedure under investigation by teams of scientists and doctors, in Berlin University and at Harvard. Here, the new ear is grown from "seeds" of cartilage taken from the normal ear. In this study, human cells are put onto a scaffolding or framework that is shaped like an ear and encouraged to grow. This process has already worked with animal tissue, and the first lab reports are expected soon.

If this method proves to be as successful as is hoped, there will be no more need to harvest ribs, the ear framework will be computer-generated for absolute perfection, and once the ear has been grown, it will simply connect into the recipient's blood supply, like a lamp-bulb into a socket.