A WORLD-FIRST trial to be conducted in Melbourne could revolutionise the treatment of chronic knee injuries using adult stem cells.

Up to 60 Victorians are to trial a simple injection scientists believe could replace drugs - and even surgery- in treating debilitating osteoarthritis.

It could also prolong the careers of athletes, including AFL players, regularly sidelined by common cartilage tears.

Melbourne-based biotechnology company Mesoblast recently completed successful animal trials of the hi-tech procedure and believe there is a "billion-dollar market" for their technique.

The Australian trials found the injection of adult stem cells - taken from human donors' bone marrow, abdominal fat, hip, skin or teeth - protected damaged knee cartilage for up to nine months.

Professor Silviu Itescu, Mesoblast's director and chief scientific adviser, said the injected stem cells bound themselves to the cartilage, halting its degen eration.

"Is it that the cells are protecting the cartilage, or is it accelerating the rate of repair? At the moment, we don't know," he said. "Either way, the result is more cartilage, thicker cartilage."

Leading sports physician Dr Peter Larkins said stem cell therapy had the potential to prolong athletes' careers. "In terms of medical break throughs, it's a sensational prospect, if it works," he said.

The human trials, to be conducted in Melbourne and in the US, will involve about 80 pa tients aged 45-55 who have had knee arthroscopes in the pre vious month.

That is the surgery track star Jana Rawlinson famously underwent to compete in the 2004 Athens Olympics. Dr Peter Ghosh, Mesoblast's chief cartilage scientist, said the weeks after arthroscopic surgery - which typically involves the removal of a cartilage called meniscus - was the ideal time to test the injection of cells.

"As you get older, (meniscus) degenerates but, more commonly in younger people, it is also torn. It is a very common injury for football and netball players," he said.

"When it's torn, it can lock the joint and give you pain and symptoms and the joint blows up. It has to be removed."

However Dr Ghosh said the surgery, known as a meniscectomy, often fast-tracks the development of osteoarthritis, the degeneration of joint cartilage that affects about 1.3 million Australians.

"So football players and men and women in the street who have had this operation live in fear that when they reach 50 or 60, they'll be faced with this debilitating disorder."

If the trials are successful, Dr Ghosh said the "off-the-shelf' product would be on the market by 2012 and could treat "any joint that can be injected".