"I am convinced polymers will take over from titanium in surgery in the coming years. Now [that] we have found a way to make them stronger, they are ideal for implants."

Titanium Alternative

Among the patients who have undergone surgery are a baby with a jaw tumor and a twelve-year-old girl who had been barely able to open her mouth from birth.

The "PolyHap" implants have been developed by teams led by Professor Steve Howdle in Nottingham and Dr. Vladimir Popov from the Institute of Laser and Information Technology in Troitsk, near Moscow, whose work is described in the current issue of Advanced Materials. Funding has been provided by the Wellcome Trust, Britain's biggest biomedical research charity.

The made-to-measure implants are light, tough, flexible and cheap, providing an excellent alternative to traditional titanium.

Professor Vitaly Roginsky, one of Russia's leading children's cranio-maxillofacial surgeons, said: "These implants allow us to carry out many more operations than before. They are easier to adjust and reshape and give us much more flexibility in our work."

Surgery Dress Rehearsal

When a child is assessed for an operation at the St. Vladimir Children's Hospital, Moscow, scientists use X-rays and tomography images to create a three-dimensional plastic cast of the damaged area. These solid biomodels, built by a high-tech process called laser stereolithography allow surgeons to plan operations with great precision before they even lift a scalpel.

Having assessed how much bone needs to be removed, the scientists in Troitsk use stereolithography to make the individual PolyHap implants. The technique, which can be completed in a matter of hours, can be used to make the most intricate shapes which are then sent to the hospital.

The outline of the implant is initially "drawn" by a laser beam which leaves a very fine coating of polymer. This process is repeated hundreds of times until the model is complete.

Ideal for Implants

So far, the Moscow operations have been carried out to correct jaw or skull deformities. But the implants can be adapted for any part of the skeleton.

"Precision is vital in this type of operation, since every injury will be unique in some way, and the patient is obviously hoping for the best possible visual effect after surgery," said Professor Howdle, from the School of Chemistry, University of Nottingham.

The success of PolyHap implants grew from the introduction of a mineral-like substance called hydroxyapatite, which makes the polymer tough and "bone-friendly." The collaborating scientists have also found a way to increase porosity -- which is important for new bone growth -- and clean out toxins from polymers using high-pressure carbon dioxide. Without this process, the implants could cause damaging reactions in the patients.

"I am convinced polymers will take over from titanium in surgery in the coming years. Now [that] we have found a way to make them stronger, they are ideal for implants," said Dr. Popov.

"Our technique allows operations to be performed more quickly and efficiently, which is better for the patient and saves time and money for the hospital."

Vanishing Implants

Although the PolyHap implants have produced good results, there is a possibility they might have to be replaced as the child grows and bones develop.

So Professor Howdle and Dr. Popov's teams have started work on a biodegradeable version, which will slowly dissolve as the repairing bone begins to re-grow.

In order to make these "vanishing" implants, they are developing a new Surface Selective Laser Sintering technique. This involves using a laser beam to melt just the polymer surface, leaving the bioactive inner section intact -- a crucial factor in creating a biodegradeable implant.

"If we can push the development on to this stage, it will mean children will only have to undergo one operation rather than several," said Professor Howdle. "The benefits from that are obvious."

'Everything Is Special'

"The technique being developed through this collaboration has some interesting innovations, and once perfected or even further developed, it should prove a great help to surgeons involved in this complex area of surgery," said Professor John Lowry, Secretary General of the European Association for Cranio-Maxillofacial Surgery.

Twelve-year-old Kseniya Gordeeva underwent a PolyHap operation in Moscow recently. She had suffered jaw damage at birth and could barely open her mouth. Kseniya had to eat through a straw, had difficulty talking, and found it almost impossible to clean her teeth. Because of the lack of normal nutritio,n she was also underweight for her age.

During a five-hour operation, Professor Roginsky removed the section of damaged bone and inserted a two-inch implant. Nine days later, Kseniya was able to open her mouth without so much effort and was clearly delighted.

"If I wanted to get my mouth open before the operation, I had to lean my head right back," she said. "Now it is much easier. I can talk like my friends and eat normally. I don't have a favorite food, because everything I eat is special."

Professor Roginsky said: "Kiseniya has made remarkable progress in a short time. We will have to do a little more work on her jaw, but the improvement is already very noticeable.

"Now she will be able to eat properly and grow into a fine, pretty girl."