The centenarian - who was a ballroom dancer into her late 90s - proved age was no barrier to the major surgery, when her right hip got an upgrade in January.

Mrs Keith underwent emergency hip hemiarthroplasty - removing the ball of her right hip joint and replacing it with an artificial ball and metal stem - at Wollongong Hospital after she fell and fractured the neck of her femur bone.

The procedure has one of the highest in-surgery death rates among all operations.

Without the surgery, Daphne would never again have been able to get out of bed.

"[The] non-surgical option would have been not to operate," said Wollongong Hospital specialist anaesthetist and clinical associate professor Natalie Smith.

"The patient will continue to experience pain and won't be able to mobilise and what inevitably happens is they will get a chest infection or a urinary infection and it will be a downward spiral and they will ultimately die."

The average age of hip fracture patients in Australia is 84.

A 2017 audit of the Australian and New Zealand Hip Fracture Registry found 5 per cent of patients who break a hip will die in hospital, and up to 25 per cent will die within the year as a result of their injury. Half of hip fracture patients never fully regain their mobility.

The prospect of spending the rest of her life bedridden was unthinkable for Mrs Keith, who until recently lived independently in her apartment, her nephew Mick Chapman, 86, said.

Even after meddling "do-gooders" moved her to an aged-care home she got around with a walker with relative ease, Mr Chapman said.

But the surgery also carried significant risks.

"She was frail and she had just had a heart attack so she could certainly die as a result of having the operation," Dr Smith said.

"But she would almost certainly die in a more slow and painful way over a period of time if she didn't have the operation."

Mrs Keith's response was: "What do I have to lose?"

"She's an amazing person," Mr Chapman said of his aunt, who turned 108 in April.

"I cannot remember her ever being sick. It just wasn't part of who she is."

Her anaesthetists decided to use general anaesthesia, rather than spinal anaesthesia, which would have numbed her from the waist down. The latter was impossible because blood thinning medication she had been prescribed for her heart attack meant it would risk a major bleed.

"There is no really good evidence that having a spinal is the safer option, but it's generally considered to be safer, because if you give someone a general anaesthetic then you are affecting their brain, heart and lungs a lot more," Dr Smith said.

Mrs Keith's recovery was "fantastic", the anaesthetist said.

"Despite being 107, and despite having to have a general anaesthetic, she was awake and alert in the recovery unit one hour after surgery, having a cup of tea with four sugars," Dr Smith said.

She left hospital four days later on the walking frame she had used before her fracture.

Almost four months later, she and her hip are doing just fine.

The anaesthetists involved in Mrs Keith's surgery - senior resident Dr Anthony Hodsdon, specialist anaesthetist Dr Rupali Kini, and Dr Smith - co-authored a report of the case that was presented at the Australian and New Zealand College of Anaesthetists' (ANZCA) scientific meeting in Kuala Lumpur this week.

They say Mrs Keith's case showed age alone was not a barrier to undergoing surgery.

"She still knew her own mind," Dr Smith said. "It was amazing that she was not delirious at her age, in pain and in hospital after her fall.

"She was completely compos mentis, processing information and making decisions."

Amid growing recognition of the dangers of futile treatment and surgeries that do more harm than good for frail and elderly patients, Mrs Keith is exceptional, Dr Smith said.

But as our population ages and people live longer, we should expect to see elective hip replacements and emergency hip surgeries become increasingly common, Dr Smith added.

"Our job is to explain it to patients so that patients are fully informed and clearly understand their decision," she said.

There is no age restriction for hip replacement in Australia, but national guidelines recommend an orthogeriatrician must be involved in the assessment of elderly patients.

Kate Aubusson travelled to Kuala Lumpur as a guest of ANZCA.

smh.com.au