Juli Dear's life was transformed by the operation

The new procedure, developed at the Royal National Orthopaedic Hospital, takes some cartilage cells from the patient and grows them in a culture solution in a laboratory.

When enough tissue has been grown, it is placed back into the knee to repair the damage.

As the original cells have come from the patient's own body, it will not reject the new tissue when it is implanted.

One patient who underwent the procedure is Juli Dear, who has had pain and weakness in the year since her injury.

'Pain free'

She said: "It was a daunting prospect and very depressing to think there is another 20 years of this, of not being able to go anywhere or do anything.

The cartilage cells are grown in the laboratory

"But I'm now pain free and I can walk long distances, and the knee doesn't collapse or give way."

Professor George Bentley at the Royal National Orthopaedic Hospital, said: "The patient should have relief from pain, and there should be a long-lasting effect.

"The methods we use now only last a few months or years."

However, demand for the new procedure could be high - an estimated 30,000 people a year in the UK suffer a knee injury which leaves permanent damage.