Obesity has become a big factor pushing people to get a joint replaced, but the outcome for an overweight person can be poor, plus the price and type of devices used can be questionable.
People classified as obese were given the majority (57 per cent) of all knee replacements in 2016, and 37 per cent of hip replacements.
The problem is that nearly half of obese patients with joint replacements had poor outcomes, including accelerated implant failure, and more likely need for repeated operations. Less than 10 per cent of "normal weight" people reported a poor outcome.
Professor of Health Systems and Services at Curtin University Andrew Briggs said choosing who gets a joint replacement surgery is not being "done well, particularly in the private sector" because the health system is not well suited to deliver other options than surgery.
One in four people, after technically successful surgery, still have ongoing pain and disability, Professor Briggs said.
Orthopedic surgery is the biggest spending item for private health insurers and it would be much cheaper for them to use non-surgical options to treat joint pain, where appropriate, such as psychological intervention, and exercise, Professor Briggs said.
"[But] the whole system not set up to support that kind of care and practitioners are funded on episodes of care, not outcomes.
"There are vested interests which are financially driven that influence what sort of care you might deliver as well."
Unnecessary knee replacement
Retired Emeritus Professor of Education at Macquarie University Kevin Harris had private health insurance and said he was pressured into an unnecessary knee replacement that ruined his retirement and quality of life.
Prof Harris tolerated osteoarthritis in his left knee for about 20 years but still led an active life. In 2004, aged in his mid-60s and freshly retired, he twisted his left knee and was advised by an orthopaedic surgeon to get both knees partially replaced, despite no pain in his right knee.
After seven months he could not stand on, bend or straighten the right knee and the pain was "constant and intolerable".
In March 2006 he had a complete right knee replacement but it was not successful and he had a revision in March 2007.
"Since then I have suffered every night and have been unable to walk," Mr Harris said. "Recently I saw yet another orthopedic surgeon who looked at X-rays and told me there 'was a real mess in there'.
"My wife and I moved to a single-storey house and I resigned myself to a sedentary life, a chair in the shower, and painkillers.
"The man living next door to me is about the same age as me and he has had a full knee replacement. He walks perfectly and goes on 40-mile bushwalks. I know for some people it works but I also know a lot of people with stories like mine."
No relief for public system
Adjunct Associate Professor at the Menzies Centre for Health Policy at the University of Sydney Dr Lesley Russell said despite 60 per cent of joint replacements being done in the private sector it doesn't take the pressure or cost away from public hospitals.
"It makes it worse because more than half of Australians don't have private hospital cover," Dr Russell said. "So most surgeons work in the private sector where they can make a lot more money which causes Medicare costs to be higher.
"[And] there is no evidence that higher charging surgeons and more expensive prostheses deliver better outcomes.
"The surgeons who do less have worse outcomes and they charge more, it doesn't matter what the surgery is, doctors who do more do better.
"[Public] waiting lists for hospitals in some cases are not outrageous but some people say 'oh well I need private health cover otherwise I'll never get my hip replaced', it's a scare campaign," Dr Russell said.
The longest median waiting time in Australia for a hip replacement was 355 days in 2016/17 at Goulburn hospital, with waiting periods above 300 days reported at many regional hospitals including Bowral, Coffs Harbour, Orange, and Maitland.
In Sydney, only Blacktown and Hawkesbury hospitals had median waiting lists of over 300 days for both hip and knee replacements. The shortest median waiting times in the state in 2016/17 were at Royal Prince Alfred Hospital in Camperdown where it was 39 days for a hip replacement, and 69 days for a total knee replacement.
Hip replacements were called 'the operation of the century' by The Lancet in 2007 but since then the devices implanted in people and how much they cost has come under scrutiny.
Tom Joyce, a Professor of Orthopaedic Engineering at Newcastle University in the UK, said the latest and most expensive new hip is rarely the best.
"The 'fashion trade' in hip replacements has been recognised for some time and in my opinion continues to this day," Prof Joyce said. "Some of the oldest hip replacements, with the best clinical results, tend to be the least expensive hips too."
Private Healthcare Australia chief executive Dr Rachel David said there's "really no evidence" that a 30-year-old design, especially for hips, is any better or worse than a recent design.
"We think this area needs constant scrutiny because we are dealing with big multi-nationals and their interests are to bump the price up," Dr David said.
The level of scrutiny on these new prostheses is "considerably less" than for new pharmaceuticals, she said.
The cost of implants for a hip range between $5,000 and $19,000, while knee replacement prostheses cost between $6000 and $15,000. The amount paid by private health
insurers for a prosthesis in the private sector can be twice the amount in public hospitals, and Australia pays higher prices than many other OECD nations, a 2017 Medical Journal of Australia report found.
Public hospitals use less expensive devices because they operate under a threshold price. Surgeons may have more choice in the private sector, but their experience with different prostheses may limit that choice. The reasons behind why the private sector pays more for these devices "is concerning", Dr David said.
"This area [new and expensive prostheses] hasn't been very transparent and there have certainly been under-the counter incentives supplied to both doctors and to hospitals to use particular medical devices," Dr David said. "Services in kind, education grants, training grants, and overseas trips.
"We are pushing for much more disclosure about those incentives through a transparency mechanism that we've been discussing with the federal government but to date, the medical device sector really lags the pharmaceutical sector in terms of what it's required to disclose.
"The inconsistency around out of pocket costs for orthopaedics is also a concern."
A Medical Technology Association of Australia (MTAA) spokesman said they worked with the federal government to harmonise prices of medical devices between the public and private hospital systems "on an aggregate level" last year.
“This action by our industry delivered cuts of $1.1 billion to the price of medical devices," the spokesman said.
“MTAA is working constructively through a number of industry working groups to deliver reforms which improve patients access to technology and increase transparency.
“Reimbursement for prostheses represents 11 percent of all Private Health Insurance costs - if you want transparency and slower premium increases you need to look at the totality of private healthcare costs including hospitals and surgeons."
The Australian Orthopedic Association (AOA), which has been running the National Joint Replacement Registry since 1999, collecting data on the performance of different devices. The registry helps identify poor performing devices helping to keep revision rates low for hip and knee replacements.
In 2017 an AOA analysis of more than 1.2 million joint replacements done in Australia (546,000 hip, 650,000 knee, and 38,000 shoulder) found 130 different combinations of implants had been used. There are 53 combinations still being used while 32 implant combinations were withdrawn from the market after some form of Therapeutic Goods Administration (TGA) intervention.
In 2017 the registry found higher than expected revisions in five new hip prostheses, and one knee replacement device.
In March 2018 the federal government reduced the minimum amount private health insurers had to pay for prostheses, saving insurers $188 million in the 2018 premium year. With more tightening over the next four years, private health insurers are expected to cut $1.1 billion dollars of expenses.
A federal government health spokesman said when the price a hospital pays for a prosthesis is higher than the benefit paid by the private health insurer, the recovery of the gap is a matter for the hospital.
"The health minister has asked the Private Health Insurance Ombudsman (PHIO) to monitor complaints about patients being charged gaps for medical devices listed on the prostheses list," the spokesman said.
The next round of prostheses benefit reductions begin on August 1, 2018.
Services listed on the Medicare Benefits Schedule (MBS) for hip and knee replacements are currently being reviewed by the Orthopaedic Clinical Committee under the MBS Review Taskforce, with recommendations expected by the end of this year, a spokeswoman for the federal Department of Health said.
Geoff Mulcahy, 77, had two knees replaced within 18 months due to "wear and tear" and is very happy with the outcome after he spent a few years trying to avoid surgery.
"I've been overweight for a long time and I played a lot of golf," Mr Mulcahy said. "It became almost impossible to stand and shave.
"I got physio and other therapies before the replacements [and] being overweight there was some reluctance from doctors for the operation with the risks of anaesthesia – they asked me to have heart tests and I passed."
It cost $30,000 each for the prosthesis, but because he had private cover it was "not really a consideration".
"I'm not terribly mobile because of my size, but I do not expect a revision. Being able to stand and walk is great."