All pain, no gain for hip patients

By Phil Taylor

An artificial joint touted as the best on the market has turned into an international medical disaster. The Weekend Herald investigates why no one here saw it coming.

Bruce Greenfield had his hip joint replaced with the ASR system in 2009, pictured right, but this month had to replace this joint with another. Photo / Sarah Ivey
Bruce Greenfield had his hip joint replaced with the ASR system in 2009, pictured right, but this month had to replace this joint with another. Photo / Sarah Ivey

Bruce Greenfield may be the last New Zealander implanted with a faulty hip joint that is causing turmoil in the orthopaedic world and heartache for patients.

As a doctor - a general practitioner - Greenfield is well placed to recognise that missteps occur in medicine and that the big money to be made can both drive innovation and delay acceptance of a problem.

That doesn't mean he doesn't feel aggrieved. "I'm pretty pissed off," he says. For a mild-mannered man, the cuss speaks volumes.

Greenfield is at home on crutches, recovering from an operation to replace the hip joint at the centre of the controversy - the so-called Articular Surface Replacement, or ASR system.

The ASR is produced by medical-device-maker DePuy, an arm of American giant Johnson & Johnson.

Greenfield thought he was getting the best hip device on the market. Instead, he has fallen foul of what has been described as "one of the biggest disasters in orthopaedic history".

The problem with the hip devices, which were touted to be market-leading, involves a controversy about how new medical devices are tested, verified and marketed.

The ASR prostheses (there is a total hip version and a resurfacing version where the ball of the femur is capped rather than removed) has been implanted in 507 New Zealanders. By the end of last year 37 had had the implants removed. The Weekend Herald has been told that many more have been removed in the seven months since those figures were compiled. Even so, the New Zealand failure rate on the available figures is four times the average - far less than overseas with one reported rate from Britain being 49 per cent.

With Australia reporting toxic readings of cobalt and chromium in some recipients of the ASR (which is made of cobalt chrome metal) the New Zealand failure rate may well rise.

Following repeat warnings of problems by Australia's joint registry, DePuy withdrew the ASRs from sale there and in New Zealand in late 2009.

A year later, in August 2010, the company "voluntarily recalled" the hips. Such a recall is no simple matter. Worldwide, 93,000 of these artificial hips have been implanted. Lawyers are all over it.

While the company has not acknowledged fault, about 1000 lawsuits have been filed in United States courts alone, accusing the medical-device-maker of knowing about problems with the ASR hip joints before it stopped making them.

Compensation is but one aspect of the recall. A lack of independent verification and the absence of clinical trials are being highlighted, as is the role marketing may have played. Did money at some point get in the way of prudence and good science?

"There's a natural tendency for companies [to think] it's probably factors other than a device, because they have invested a lot of time in it," Professor Stephen Graves, an orthopaedic surgeon and head of Australia's joint registry, recently told the British Medical Journal. "It does take some time on occasions to convince a company that there may be problems with the device."

By 2007, four years after the ASR came on the market, Graves' registry was reporting that the devices had a high revision rate. And it kept at it, warning Australia's regulators and DePuy 17 times between 2007 and 2009.

Because he was one of the last to be implanted with an ASR (about six years after they were first used and a few months before they were withdrawn in New Zealand), Greenfield considers himself "unlucky" rather than a guinea pig. Left hanging is the possibility that those who received the devices soon after they came on the market were.

There were no clinical trials. Pre-market testing included fitting the joint into foam blocks which critics say does not equate to the male human pelvic bone or biology. Such dry runs also enable perfect cup placement that is not easy to achieve in reality.

Criticism of the ASR includes that its design did not allow a practical margin for input error, that it risked "edge loading", that the cup was too thin and susceptible to losing shape, and that clearance between ball and cup was too small.

"The ASR looks good on a kind of robotic analysis but you have to put the cup in absolutely perfectly," a senior New Zealand orthopaedic surgeon who chose not to use the ASR told the Weekend Herald, "otherwise you likely get dry-bearing and edge-loading. It is very hard for humans to put in perfectly. A little off and it's prone to failure."

The surgeon did not want to be named "no one wants to put their head above the parapet too much on this" but predicts the New Zealand revision rate will rise. "My personal view is probably that all of these [ASR] hips need to come out."

Given his situation, Greenfield is strikingly reasonable. "On the one hand, without these companies and without them making massive profits we wouldn't have all the wonderful products modern medicine has got, but at the same time, one needs a fair degree of skepticism because they are profit-making operations." History, he says, demonstrates that medical companies haven't always been above board.

The ASR was developed in response to the success of a rival metal-on-metal product, the Birmingham hip which enjoys good success as do most metal-on-metal options.

Metal implants are expected to last longer and therefore are a better option for younger active males with arthritic hips.

The 507 Kiwis implanted with the problematic ASR hips make up a small percentage of the 63,694 hip replacements done in New Zealand during the decade to 2010, and hip replacements continue to be regarded as among the most beneficial operations because of the improved quality of life they usually deliver.

Having implanted ASR joints into 126 patients, Auckland surgeon Garry Heynen appears to be the biggest user. He points out that the figure makes up about 5 per cent of all hip replacements he has done since he began using the ASR in 2005 and stopped in July or August 2009.

"July 22, 2009." Greenfield stresses the date of his ASR total hip implant operation. It is significant, of course for the hole it has made in his life: the quality of life it promised but didn't deliver, the risk entailed in a second operation under general anaesthetic and the pain he describes as "unremitting". "It has totally ruled my life for two years."

The date is significant too because it appears flags were long being waved behind the scenes about a possible problem with the devices beyond Australia.

British orthopaedic surgeon Tony Nagel began using the ASR in 2004, wooed by company claims the hip resurfacing device would out-last a competitor's product. In early 2007 some of Nagel's patients reported groin pain and difficulty walking. When he operated, Nagel found soft tissue and muscle around the hip were destroyed and a pus-like fluid coming from the device. Tests ruled out infection.

Tom Joyce, a University of Newcastle biomedical engineer examined some of the failed implants and believed the mirror-smooth finish needed to optimise the body's natural lubrication had roughened, causing metal to grind on metal, something which could explain high cobalt and chromium readings in some patients.

The company's response was the same it gave the Australians - it blamed surgeon technique.

Heynen, who has implanted a quarter of the ASR devices used in New Zealand, told the Weekend Herald he got the same response.

In letters to patients Heynen has described the ASR as having "a significant design fault" and that after seven years of use "there is a higher than normal failure rate associated with increasing wear, metal sensitivity and loosening of implants ..."

This month he recommended that his ASR patients have blood tests to determine cobalt and chromium levels. Of those done, some were normal, some "a little higher" and one at a level that has prompted him to recommended the patient consider having the joint replaced even though his scans and x-rays appear okay.

Heynen told the Weekend Herald he had a history of successful use of metal-on-metal products (including with another DePuy device) and was persuaded to use the ASR for a specific group of patients by the company's data. "Being a metal-on-metal hip replacer, I guess I was drawn in by what the company said."

As time passed he began to see unusual occurrences, stems or cups coming loose and patients having ongoing discomfort. "It took a long time to filter through in terms of a problem. I started having concerns to the point I stopped doing them."

"I wasn't aware of anything happening internationally at that time ... Australia or anywhere else and I hadn't read anything or seen anything in the literature."

He says he wasn't aware of a 2005 critique of the ASR - given at a conference and available on the internet - by the architect of the Birmingham hip, Derek McMinn, which outlined design faults McMinn predicted would result in device failure.

"At the time I was doing the ASR hip," says Heynen, "had I needed a hip replacement I would have had one myself. That's how happy I was with what was presented to me [by DePuy] as the science."

"Had I had one I would be in the shit now too. It's an absolute travesty and it's going to be the most telling thing in my whole career but it is one of those things."

The company is paying out-of-pocket costs for patients who need the ASR replaced but because of ACC, New Zealanders can't sue for pain and suffering.

"I think that if DePuy and Johnson & Johnson try to hide behind ACC, that's an absolute travesty," says Heynen. "I hope they have the ethics and the morals to treat the New Zealand patients as they do the rest of the world in terms of getting some compensation for all the heartache and grief they are facing."

Major flaws in the system

The government agency tasked with ensuring that medical devices used here are safe did not check the ASR hip system and has not posted its recall on its website.

New Zealand's performance reflects the flawed regulation of medical devices slammed by the British Medical Journal as "unsatisfactory, unscientific, and in need of a major overhaul".

Medsafe's job is "to enhance the health of New Zealanders by regulating medical devices to maximise safety and benefit". But there is no approval process in the Medicines Act for medical devices.

Medsafe said Johnson & Johnson informed it of the recall of the ASR devices but the company "handled the communications concerning the recall".

Asked how Medsafe satisfied itself the ASR devices were safe and fit for purpose, a reply attributed to compliance manager Derek Fitzgerald who said that the devices had been approved by the US Food and Drug Administration, Australia's Therapeutic Goods Agency and was "CE [European conformity] marked in Europe".

"These regulators carry out assessments of medical devices pre-market," Mr Fitzgerald said.

However, checks indicate that Australia did not assess the ASR and the US agency approved only one of the two ASR systems.

In its editorial, the British Medical Journal said the way in which CE marks were issued was flawed. " Usually there is no need to provide proof of clinical efficacy."

"The process of approving medical devices must be entirely overhauled ... We still have far to go to minimise competing interests that influence patient care."

- NZ Herald

Your views

© Copyright 2014, APN New Zealand Limited

Assembled by: (static) on production apcf01 at 24 Oct 2014 21:50:46 Processing Time: 453ms