Peter Heffernan's arthritis-riddled right knee partially collapsed as he hurriedly jumped from a pergola on the day of the 2003 Canberra bushfires, and within a month he went under the knife for a total replacement.

The effects of an apparent infection were clear to the former plasterer within days.

"Even the day after I got out I could feel my leg getting tighter and tighter," Mr Heffernan said. ''I went to my GP and said this pain in my right knee is getting unbearable.

"There was a little white spot on the top of my leg, 50 to 60 millimetres above my knee. When he pricked it, 180 millilitres of stuff came out."

It was confirmed that March that the knee was infected with a ''superbug'' known as methicillin-resistant staphylococcus aureus (MRSA), a potentially deadly bacteria that can withstand many common antibiotics.

Mr Heffernan, 59, said the infection lasted for more than a year, contributing to the knee replacement failure.

"As a result there was nearly two years on and off in hospital, and more than 20 general anaesthetics since 2003, all on the right leg," he said.

"If I hadn't had the infection I wouldn't have had to have two different knee replacements.

"The last one looked like it was going to work until I bled back into the new joint."

Instead he had his right leg amputated above the knee in 2011, and has since had a further 22 centimetres amputated. It now appears a functional prosthesis is unlikely.

A left-knee replacement meant Mr Heffernan was on a disability pension from 2000, but he had expected to return to work and his active lifestyle if not for the other joint's problems.

"For a person that used to go fishing and pig-hunting and everything else, I just haven't been able to do it," he said. After weighing in at 93 kilograms in late 2002, the wheelchair-bound Duffy resident said he would now be beyond 130kg.

Fairfax Media revealed last year that three ACT women had needed to have their legs amputated in recent years after they caught infections during or after apparently simple knee replacements at Calvary Hospital. Two of the patients were at Calvary Private Hospital, with the third at Calvary Public.

A Calvary Health Care ACT spokeswoman said the health provider had no comment, including on questions about hand-washing and use of gloves by nurses.