FOR six years, housewife Sin Gek Joo, 54, was held hostage by her failing knees.

The cartilage was so worn down that the bones in her knee joints would grind painfully against each other when she walked.

She found relief last year when doctors completed a revolutionary procedure that offers patients an alternative to painful knee replacement surgery.

Doctors from the National University Hospital (NUH) used MadamSin's cells to grow a tiny amount of cartilage in a laboratory and implanted it into her knee joints. The cells proliferated and filled the spaces between her bones, putting an end to the grinding.

'I used to have to go up and down the stairs sideways, like a crab, to ease the pressure on my knees. Now, there's no more pain,' she said in Mandarin.

She is among about 100 patients who have had their cartilage repaired this way at the NUH under Associate Professor James Hui since 2002. The operation costs about $15,000 per knee and requires a week's stay in hospital.

As for knee replacement surgery, bone is replaced with plastic and metal at a cost of about $12,000 per knee. However, the new knee would still be prone to wear and would feel unnatural, said Prof Hui.

About 5,000 people here resort to total knee replacement surgery each year, added the senior consultant at NUH's orthopaedic surgery department.

Before the stem cell treatment was available, there was no treatment for worn-down cartilage, said Prof Hui. 'People just bore with the pain till it got so bad they had to go for total knee replacement.'

To grow cartilage in a petri-dish, doctors took stem cells from Madam Sin's bone marrow and coaxed them to grow into cartilage.

The cells, prized for their adaptability, can also transform into bones and tendons, among other things.

Cartilage implants derived from bone marrow stem cells are also done in Japan and Taiwan. Countries such as the United States and those in Europe use cartilage cells as the use of stem cells is more controversial there, said Prof Hui.

He has yet to use embryonic stem cells, the master cells which can transform into any cell in the body, in these procedures.

Doctors usually use adult stem cells found in fat, blood or brain tissue. Similar procedures have been used to grow new skin for burn victims.

Prof Hui is now testing a way of replacing cartilage without using his scalpel.

In what has been described as a world first, he is injecting stem cells into patients' knees rather than slicing the kneecaps open to implant them. He has completed a trial with 15 patients.

Dr Chang Haw Chong, 40, consultant orthopaedic surgeon at Changi General Hospital and Gleneagles Medical Centre, said that if the method works, it could be a boon for patients.

'It can save four to six weeks of recovery time. They can save on hospitalisation and surgery costs as it can be an outpatient or day-surgery procedure.

'It's still experimental but it's safe. So even if it doesn't work, there's no harm done to the patient.'

Prof Hui presented his findings at a two-day stem cell symposium, under the UK-Singapore Partners in Science programme.

The symposium, which ended yesterday, was organised by the Agency for Science, Technology and Research and the British High Commission here.

wycin@sph.com.sg

This story was first published in The Straits Times on Mar 19, 2008.