Tag Archives: hip replacements

No cancer rise in hip implant patients – Behind The Headlines – Horncastle News

“There is no evidence that metal-on-metal hip replacements increase the risk of cancer,” the BBC reported today.

The story is based on a study that found that patients with metal-on-metal hip replacements did not have a higher risk than the general population of developing cancer up to seven years after surgery, or than patients with hip replacements made of other materials.

The study comes in the wake of recent concerns about metal-on-metal hip implants, including high failure rates and the possible risks of small amounts of metal (ions) being released into the body. While the findings are reassuring, this type of study has limitations. in particular, it only looked at the risk of cancer within a few years of having hip replacement surgery. given that several cancers can take many years to develop, a study of longer-term outcomes of metal-on-metal implants is required and recommended by the researchers.

Recommendations from UK health regulators state that people with large metal-on-metal implants should be monitored annually. If they have any concerns, they can consult their doctor for patient-specific guidance.

The study was carried out by researchers from the University of Bristol, University of Exeter and Wrightington Hospital, Wigan. it was funded by the National Joint Registry for England and Wales.

The study was published in the peer-reviewed British Medical Journal, which has recently published a number of pieces on the wear rate and safety of metal-on-metal hip implants. Most notably, it conducted a joint investigation with BBC’s Newsnight.

The research was reported fairly by the media. both the BBC and The Daily Telegraph pointed out that the study only looked at cancer rates up to seven years after surgery, and that ongoing monitoring may need to be performed.

The authors point out that metal-on-metal hip implants have become popular over the past decade. these consist of:

  • resurfacing implants – where only the articulated surfaces of the existing hip joint are replaced with metal 
  • ‘stemmed’ implants – in which the ball replacing the top of the thigh bone and the artificial socket placed in the pelvis are made of metal. As their name suggests, stemmed implants feature an elongated metal stem that surgeons slide down into the thighbone to secure the implant in place

However, recent data show that all-metal stemmed implants have significantly higher failure rates and that metal-on-metal resurfacing implants have an above-average failure rate compared with implants made of other materials (such as ceramic or plastic).

In addition, the researchers say that little is known about the biological effects of the metals – predominantly cobalt, chromium and molybdenum – which are released into the body as the surface of the implants wears down. The researchers say that traces of these metals can be found in many organs, including the marrow, blood, liver, kidneys and bladder. they also say there is evidence that patients who have had joint replacements show a higher than normal incidence of DNA (genetic) damage, although there is no proven link between this and an increased risk of cancer.

To assess any raised risk of cancer, this study compared rates of cancer in patients with metal-on-metal hip implants to rates in patients with hip replacements made of alternative material, within seven years of surgery. it also compared cancer rates in patients undergoing hip replacements with those of a section of the general population, with predicted cancer rates matched for age and sex.

The researchers used data on hip replacements from the National Joint Registry of England and Wales, a database that holds records on over 1 million joint replacement procedures undertaken since its establishment in 2003. Researchers consulted all relevant data up until April 2011. The Registry is also linked annually to national hospital episode statistics data, in order to routinely monitor health information on patients who have had joint replacements. The hospital episode statistics data collection contains details of all admissions to NHS hospitals in England. it includes private patients treated in NHS hospitals, patients who were resident outside England and care delivered by treatment centres (including those in the independent sector) funded by the NHS.

For their study, the researchers used data from 289,571 patients in England who underwent hip replacements from 2003 to 2010, for whom joint registry data could be linked to hospital episode statistics. This comprised 40,576 patients who had metal-on-metal hip replacements and 248,995 who had hip implants made of other materials.

The researchers looked at hospital episode statistics data on these patients between 1997 and 2010, including any diagnoses of cancer (other than non-melanoma skin cancers) in the years after hip replacement. they also looked separately at specific cancers suspected of being related to metal ions, including blood cancers (such as leukaemia), malignant melanoma, prostate cancer and renal tract cancer (cancer of the bladder, ureter or kidney). they excluded from their analysis any patient who had a recorded diagnosis of the specific cancer before or at the time of their hip replacement.

They compared the outcomes in patients with metal-on-metal hip replacements (both stemmed and resurfaced) with patients who had hip implants made of other materials. they separated patients into three groups: those with stemmed metal implants, those with metal resurfacing, and total hip replacement with other materials. they adjusted their results for other factors that might affect the risk of cancer such as age, sex and general health.

In addition, they compared cancer rates in patients undergoing any type of hip replacement with those in the general population, using age- and sex-matched predicted incidence rates derived from national data.

The study found that, compared with patients who had hip implants made of other materials, there was no evidence that metal-on-metal implants were associated with an increased risk of any cancer diagnosis in the seven years after surgery. This was based on an average (mean) follow-up of three years, with 23% of patients observed for five years or more. Similarly, there was no increase in the risk of malignant melanoma or cancers of the blood, prostate and renal tract.

For men aged 60, the risk of being diagnosed with any cancer in five years after surgery was:

  • 4.8% (4.4% to 5.3%) after metal-on-metal resurfacing
  • 6.2% (5.7% to 6.7%) after a stemmed metal-on-metal implant
  • 6.7% (6.5% to 7.0%) after a hip implant made of other materials

For women aged 60 the rates were lower:

  • 3.1% (2.8% to 3.4%) after resurfacing
  • 4.0% (3.7% to 4.3%) after a stemmed metal-on-metal implant
  • 4.4% (4.2% to 4.5%) after other types of material

The researchers also found that one year after hip replacement, the incidence of new diagnoses of cancer was 1.25% (95% confidence interval [CI] 1.21% to 1.30%). This was lower than the predicted incidence of 1.65% (95% CI 1.60% to 1.70%) for the age- and sex-matched general population.

The researchers said the findings are reassuring and pointed out that, compared with the general population, the risk of cancer for hip replacement patients is low. however, they also said that a study of longer-term outcomes is needed.

This study’s strength lies in its large sample of patients who have had hip replacements. however, it should be noted that:

  • The study only shows results for up to seven years after surgery. since some cancers take time to develop, an analysis of longer-term data is required.
  • All hip implants produce some metal ‘debris’, even if the surfaces are not metal. it would, therefore, be better to compare the cancer rates of patients having metal implants with a control group of patients with osteoarthritis without any implants. The registry used does not include data on these people.
  • The fact that the study found lower cancer rates after one year in patients with metal-on-metal implants compared with the age- and sex-matched ‘normal’ population is not easy to explain. it may indicate the influence of other factors (confounders) because patients undergoing hip replacements are checked to ensure they are healthy before surgery. People of the same sex and age in the comparison group may not be as healthy. in the comparison of different hip replacement types, those selected for resurfacing may also be younger and fitter as this is one of the reasons these devices are fitted. these confounders could have explained some of the effect reported.
  • Using hospital statistics to identify cancers may underestimate cancer risk. This is because some patients are diagnosed and treated without hospital admission, for example only as outpatients.

While these findings offer some reassurance about the potential carcinogenic effect of hip replacement implants, further longer-term study of the effects of metal-on-metal implants is required. given the various concerns about these types of implants, it is likely that their use will be reduced in future and that monitoring of any cancer risks will continue.

No cancer rise in hip implant patients – Behind The Headlines – Horncastle News

Metal hip replacements under scrutiny after new recall

Richard Stone holds an X-ray of his pelvis and prosthetic hip, in Palm Beach, Fla. (Steve Mitchell/Associated Press)

A new kind of hip replacement – that’s supposed to last years longer than the standard type – is being recalled by another manufacturer, while the U.S. Food and Drug Administration plans to review how safe the devices are for patients.

One of the manufacturers of the devices, British-based Smith & Nephew, recently recalled a liner used in so called metal-on-metal hip replacements. The company said in a statement that it was “not satisfied with the clinical results” it was seeing.

It’s the fourth company to recall or suspend sales of the implants, which were introduced in the mid-2000s and billed as a more durable option compared to the traditional metal-and-plastic type.

But compared to standard hip replacements, research studies have suggested that those using a metal ball and a metal cup are more than three times more likely to fail, and can cause tissue damage around the joint.

Health authorities concerned

After approving the metal devices for use around the world, government watchdogs have been taking a second look at them.

In April, Health Canada issued a safety advisory saying that metal-on-metal implants can cause pain, “soft tissue reactions,” and that the implants can become loose.

Patients with the implants who have painful hips and an MRI showing tissue damage should have the devices removed, the agency said. and all patients with metal-on-metal hips, even if they have no symptoms, should be monitored by their surgeons.

South of the border, the U.S. Food and Drug Administration has said that it has “concerns” about the devices, cautioning that the metal ball and metal cup slide against each other so that “some tiny metal particles may wear off of the device and enter into the space around the implant,” and that the metal particles “may even get into the bloodstream.”

Later this month, the FDA plans to review how safe the devices are for patients. a public meeting is set for June 27 and 28, where the agency said will seek expert opinions on “the risks and benefits” of the devices, based on the available science.

Canadians affected

Thousands of patients in Canada have had a metal-on-metal hip replacement since they were introduced. Some have since had them removed. for many others they’ve become a source of worry.

Frank Cristo underwent the procedure five years ago, but he said the pain he had been experiencing only got worse so he had the implant removed and is waiting to have it

‘I was good for the first month or so, then I started feeling pain all the time.’—Frank Cristo, hip-replacement patient

replaced with the metal-and-plastic type.

“I was told metal-on-metal was supposed to be the best,” he said. “I was good for the first month or so then I started feeling pain all the time.”

Cristo isn’t alone. about one in 100 patients experience inflammation and pain. Canadian research suggests a smaller number develop something called pseudo tumors that cause serious muscle and tissue damage.

And the number of people complaining of problems related to a metal-on-metal hip replacement is on the rise in Canada, according to Dr. Nizar Mahomed, the head of orthopaedic surgery at Toronto Western Hospital.

“We are just starting to see the increased numbers of revisions or failures in the metal to metal prosthesis,” he said. “I hope that it stabilizes, but there are still concerns that the number of failures will continue to increase with time.”

Role of health authorities questioned

A recent study of 22 Canadian patients with metal-on-metal implants found that the devices failed in two of the cases.

Dr. Ross Leighton, who helped conduct the study and is a former president of the Canadian Orthopaedic Association, believes there weren’t enough independent studies of this type of implant before they were approved.

“It really comes down to Health Canada really having enough stringent criteria before they bring out a new component,” he said.

Health Canada says its approval requirements are among the most stringent in the world.

Companies that manufacture the metal devices say they continue to make and improve on them.

With files from CBC’s Pauline Dakin

Metal hip replacements under scrutiny after new recall

All-metal hips ‘wear down faster’ – Health – Derbyshire Times

Published on Saturday 21 April 2012 03:08

“Experts are calling for controversial metal-on-metal hip implants to be banned,” according to the Guardian. the newspaper said that research has found “unequivocal evidence” of high failure rates of these implants, particularly among women.

In recent months there has great deal of scrutiny about the safety of some types of metal-on-metal hip replacements, with concerns they wear out much faster than implants featuring plastic and ceramic parts.

To examine the issue, researchers working on behalf of the National Joint Registry in England and Wales analysed data on 402,051 hip surgeries performed using implants attached to the thigh bone by a metal stem, including 31,171 metal-on-metal implants. Researchers found that these had higher failure rates than other types of hip replacement, with an overall five-year failure rate of 6.2%. those with larger ‘heads’ (the part of the implant fitting into the hip joint socket) had a higher failure rate than those with smaller heads, as did hip implants in women.

This study provides more information on the longer-term performance of metal-on-metal hip replacements, and supports claims that they do not last as long as other types of hip implants.

The use of this type of implant in England and Wales is reported to have dropped dramatically since 2008, and the ongoing concerns seem likely to reduce its use further. overall, this study supports the recent recommendations by UK health regulators. it states that people with large-headed metal-on-metal implants should be monitored carefully over time to identify whether their implants are wearing down at a faster rate.

The study was carried out by researchers from the Universities of Bristol and Exeter, and the Centre for Hip Surgery at the Wrightington Hospital in Lancashire. it was performed on behalf of the National Joint Registry of England and Wales, which also funded the research.

The study was published in the peer-reviewed medical journal the Lancet.

This story was covered in a balanced way by the Guardian.

In recent months there has been some concern over the use of certain all-metal hip implants, particularly over whether they wear down at a faster rate compared to other types of implants.

Hip implants come in a variety of different sizes and materials, but the debate has centred on large-headed ‘metal-on-metal’ implants. these implants are designed so that both the ball replacing the top of the thigh bone and the artificial socket placed in the pelvis are made from metal.

This research was a registry study looking at data on hip implants collected by the National Joint Registry of England and Wales, which records all hip and knee replacement surgeries. this includes the first operation to install the implant, and any revision operations carried out to replace or remove part of the original implant.

Just like with natural bone, metal hip implants experience wear and tear and can eventually deteriorate. this means any implant may eventually need revision surgery, although analysing the revision rate gives an estimate of how often and how soon implants fail early. while the revision rate is an important indicator of the outcomes of hip replacement, it should be noted that not all hip implants that do not function well or cause pain will be replaced.

The researchers say that due to their resistance to wear, large diameter metal-on-metal hip stemmed implants have become popular. ‘Large diameter’ refers to the size of the ‘head’ part of the implant that sits in the hip socket section of the implant. Stemmed means the head is attached to an elongated stem that sits inside the top of the high bone and holds the head in place.

The study’s authors note that there have been concerns about the high failure rate of one particular brand of metal-on-metal hip stemmed implant called ASR, which was withdrawn from use in 2010. given this withdrawal and fresh concerns about other types of metal-on-metal implants, the researchers aimed to look at whether general metal-on-metal hip stemmed implants fail any more regularly than other hip implants (ceramic-on-ceramic or metal-on-polythene). they also looked at whether large diameter hip implants lasted any longer than implants with smaller diameter heads.

This type of registry analysis is useful for monitoring the long-term performance of devices once they are in use. it can help to identify any problems that are occurring with the implants. Ideally, data on the comparative performance of different implants would come from randomised controlled trials, but the researchers report that there are few such studies available.

The researchers looked at 402,051 first total-hip replacements using a stemmed implant carried out in England and Wales between April 2003 and September 2011. they then identified any revision operations carried out on these hip implants. This allowed them to determine how long it took before a revision operation was needed for each type.

The researchers did not include data on ASR implants in their analysis, because they are already known to have much higher revision rates than other brands and have already been withdrawn from the market. the researchers also only included data on hip replacements that had sufficient data recorded to allow them to identify which operations were revisions of which earlier hip replacements. this allowed them to analyse data on 82% of all first total-hip replacements using a stemmed implant performed in the study period.

The researchers tried to make sure the hip implant operations being compared were as similar as possible. for example, they only included those where the implants were not ‘cemented’ in, and where the operation was being performed in ‘typical’ patients.

Typical patients were defined as those whose hip replacement was needed due to osteoarthritis only, and who were generally healthy or with only mild illness at the time of primary surgery. this was defined using a recognised measure of pre-operative health. the researchers also took into account the age of the patient, and looked at men and women separately.

The researchers found that metal-on-metal hip implants were used in 8% of the 402,051 first total hip replacements using a stemmed implant. this equated to 31,171 replacements. use of these types of implants peaked around 2008 but then reduced sharply after this.

Overall, metal-on-metal implants required revision due to failure more quickly than other implants, with a 6.2% needing revision within five years of implantation. the size of the head of the metal on metal implant affected the failure rate in men and women, with larger heads failing earlier. overall, each 1mm increase in head size increased the risk of revision over time by about 2% (hazard ratio [HR] 1.020 in men, 95% confidence interval [CI] 1.004 to 1.037; HR in women 1.019, 95% CI 1.001 to 1.038).

In men aged 60 years, the five-year revision rate was 3.2% for 28mm head metal-on-metal implants, and 5.1% for 52mm head implants. In younger women, the five-year revision rate was 6.1% for 46mm head metal-on-metal implants, compared with 1.6% for 28mm head metal-on-polyethylene implants.

Revision rates for metal-on-metal implants were higher for women than men, even with implants with the same head size. for example, a 36mm head metal-on-metal implant in women aged 60 had a five-year revision rate of 5.1% compared to 3.7% among men of the same age and implant head size.

However, larger head sizes were more durable for ceramic-on-ceramic hip implants. In men aged 60 years, the five-year revision rate was 3.3% with 28mm head ceramic-on-ceramic implants, and 2.0% with 40mm head ceramic-on-ceramic hip implants.

Age also had an effect on hip implant survival for women, with younger women receiving hip implants more likely to have revision surgery.

The most common reasons for revisions were loosening and pain, and these were more common in people who had metal-on-metal implants.

The researchers concluded that metal-on-metal stemmed hip implants have a higher failure rate than other options, and should no longer be used. they say all patients with these types of implants should be carefully monitored, particularly young women whose hip implants have large diameter heads. they say that their findings support the continued use of large diameter ceramic-on-ceramic bearings as they seem to perform well.

Metal-on-metal hip implants have been under intense scrutiny in recent months, and this analysis provides useful data on how often they require revision and how they compare to hip implants made of other materials. overall, this research indicates that metal-on-metal hip implants have higher revision rates (rates of replacement) than other types of hip implants in England and Wales.

As with all such studies, there is the possibility that factors other than the implant type differed between the groups being compared, and that these other factors may influence the results. the researchers tried to minimise the risk of this by:

  • comparing similar operations in similar patients
  • looking at men and women separately
  • looking at the effect of age and implant head size

However, there are other factors such as activity levels that could still be having an effect.

As the data used in this study came from a surgical registry, not a lot of information was available about factors such as body mass index (BMI) or activity levels. these two factors could potentially influence the stress implants are placed under and therefore the wear that they display. the researchers say that in their opinion there is no obvious reason to suppose that these factors would vary to a large extent between people receiving the different large head metal and ceramic hip implants.

Due to these inherent limitations with observational research it is difficult to conclude that the differences seen are definitely due to the implants alone. the advantage of this registry data is that a large number of people were assessed. furthermore, this is not a selected subsample of people receiving hip implants but all patients from different surgeons and using different implants. the researchers say that these strengths and the consistency of their findings support the suggestion that these findings do represent the true effects of the implant types.

Overall, these findings do seem to suggest that metal-on-metal hips do require revisions more frequently than other types of hip implants. this study reports that since 2008 there has been a dramatic reduction in the use of metal-on-metal hip implants in England and Wales. overall it found that most hip replacements analysed in the study period (92% between April 2003 and September 2011) did not use metal-on-metal implants.

It seems likely that based on this study their use may decline further. it is important to bear in mind that the overall five-year revision rates with metal-on-metal hips is 6.2%, so the majority of these implants have not needed revision in this time. this study supports the authors’ suggestion and MHRA recommendation that people with these implants should be monitored carefully over time, to identify when such revisions might be required.

Analysis by Bazian

All-metal hips ‘wear down faster’ – Health – Derbyshire Times

Hip patients: Why weren’t we told?

New Zealand patients are angry that medical authorities and some surgeons failed to act on warnings that their hip replacements had failed. as the victims join a British lawsuit against manufacturers Johnson & Johnson, Phil Taylor reports on their painful fight for justice

Sanda Lawton remembers to the day her first indication that there was a problem with her hip implant. It was October 2008 while she was hiking in the Hong Kong hills. “I stopped dead in my tracks because I was getting these terrible pains in my groin.”

A gradual decline ensued in the otherwise fit and healthy 67-year-old. Unable to lift the infant she was caring for, she had to give up her job as a nanny in Hong Kong. Lawton has since had to give up the part-time work she found after returning to live in Auckland. “I really have doubts that I’ll be able to bend from the waist again,” she says.

the pain that began on the trail in Hong Kong led her on an odyssey that eventually resulted in surgery last October to replace the metal ASR cup with a ceramic one. this was almost four years after the ASR was fitted and in that time she says she was pain-free for just 11 months.

She regularly reported the pain to doctors but says it was dismissed. “So I just kept thinking the pain was in my head.”

Eventually an ultrasound revealed a pseudo-tumour near her hip a painful mass of soft tissue and fluid surrounding the joint. A blood test revealed concerning levels for cobalt and chromium.

These discoveries came after she received a letter dated July 22 from her surgeon, Gary French, informing her of the ASR recall. this was 11 months after the hip manufacturer, Johnson & Johnson subsidiary DePuy, advised surgeons to inform patients of the recall, and three weeks after the Herald first reported the ASR failure in New Zealand.

“I looked at the letter and burst into tears. It was like, ‘it’s not in my head after all, I’m not going crazy’. Then I pulled myself together and got angry and I’ve been getting angrier ever since.”

her revised hip dislocated last month, possibly due to tissue destruction resulting from the ASR.

Lawton says she doesn’t blame her surgeon for problems with the ASR but is disappointed at the delay in informing her of the recall.

another of French’s patients who suffered hip pain and has since had the ASR replaced told the Herald the surgeon notified her a year after the recall, by which time she had learned of it through the media.

French, who is overseas, did not respond in time for this article.

Stuart Willis, whose ASR hip was replaced last December after six years, was not notified at all by his surgeon, Jeremy Earl. Willis, a Whakatane accountant, 69, had high metal readings and is concerned about lost time caused by the failure to notify him and worried about possible health consequences.

Earl has apologised and told Willis he had moved from the region and understood a DePuy representative would notify his ASR patients. Earl refused to discuss the matter with the Herald.

the Herald asked Health Minister Tony Ryall whether he was comfortable that Medsafe did not list the ASR recall on its website when other product recalls were listed.

He replied; “As part of the new joint agreement with Australia, which comes into effect July 1, I would expect such recalls to be listed on the joint website. the fact that it hasn’t reflects Medsafe’s past practice and this will be changing.”

In a statement last year attributed to its head of compliance management, Derek Fitzgerald, Medsafe said Johnson & Johnson notified it of the recall but the company handled communications itself. this had included hand-delivering letters about the recall to the 31 surgeons trained in installing the device, advising 44 hospitals, and mailouts to 218 general orthopaedic surgeons.

“Medsafe agreed with the company that, because of the need for clinical assessment, this was the most appropriate and effective means of communicating the recall.”

There were two versions of the ASR prosthetic, a total hip replacement and a hip resurfacing option. Both used the same critical component, a solid metal cup that replaced a patient’s hip socket.

There are claims that the component was flawed in design.

the concern is that as the hip replacements wear, metal particles can be released, potentially destroying muscle and ligaments surrounding the joint and producing toxic levels of cobalt and chromium. There is no conclusive evidence either way about the health implications of high levels of these metals, though a British government health committee in 2006 said “it gave rise to concern because this may present a potential risk of carcinogenicity [cancer] in humans”.

Patients have reported a range of ailments including skin conditions, headaches and hearing problems which they worry may be related.

Up to 50 New Zealand patients have this week instructed a London barrister to seek compensation in England where the ASR was made. ACC legislation prevents them from suing for pain and suffering here.

In the wake of the recall the spotlight is on the lax system of checks on medical devices. the problem is that artificial hips, breast implants and other devices which are implanted in people do not undergo the same rigorous tests as drugs.

Drugs have to go through years of clinical trials but ” you could get a device through with a two or three-day literature review and no clinical data requirement”, Carl Heneghan, director of the Oxford-based Centre for Evidence-Based Medicine recently told the BBC.

In an internal email written a year before the ASR was recalled, a Johnson & Johnson executive reported that the United States Food and Drug Administration had refused to approve the ASR after reviewing company studies that showed it had failed prematurely in “significant” numbers, the New York Times reported last month.

the email, which was among thousands of company documents released to lawyers suing Johnson & Johnson, noted there had been “a significant number of revisions in the ASR group” compared to “very few in the control group”.

the executive noted that providing more information may not change the FDA’s decision and might carry “additional downside risk” for the company. the August 2009 email referred to complaints about early failures. At that time the device was being questioned in Britain and in Australia, where regulators were pressing DePuy to remove the artificial hip there or face having it forced off the market.

three months later, in December 2009, DePuy withdrew the ASR from Australia and New Zealand, citing flagging sales. In August 2010 it recalled the device worldwide. the hip had been implanted in 93,000 people worldwide.

the recall came after data from the England and Wales hip registry showed about 13 per cent of the ASR hips were failing within five years, more than triple the usual rate. the failure rate in Britain has since been reported to be 49 per cent and some experts predict all of them will need to be removed.

the US had requested clinical trials for the resurfacing version of the hip because that was a new procedure. Meanwhile this version was able to be sold elsewhere. while the clinical trials were under way, DePuy was able to market the total hip replacement version in the US from 2005 due to a regulatory loophole which allows through products similar to ones already on the market.

throughout the episode the company blamed surgeons for the higher failure rate, saying doctors were not positioning the component properly. but the clinical findings rejected by the FDA came from ASR studies run by surgeons DePuy handpicked, including some who helped develop the implant and had received royalties and fees.

Concerns were raised last month in the British Medical Journal about all metal-on-metal devices where the pelvic cup and head of the femur are both made with a cobalt-chrome alloy.

the journal’s investigations editor, Dr Deborah Cohen, wrote that “hundreds of thousands of patients around the world may have been exposed to toxic substances after being implanted with poorly regulated and potentially dangerous hip devices”.

the use of metal grew because metal cups were more durable than plastic. but Cohen says the dangers arising from metal toxins escaping into the bloodstream as the device wears down has long been known. “Patients have been kept in the dark about their participation in what has effectively been a large uncontrolled experiment.”

In response to the article, Britain’s MHRA (Medsafe’s equivalent) said there was “a small risk” of patients suffering complications from having metal-on-metal hip implants and recommended surgeons and doctors monitor them annually for the lifetime of their implant.

after studying metal hips in 2007, the regulatory body ruled that patients should sign a pre-surgery consent that spelled out the risks of metal debris. but, writes Cohen, the requirement was not communicated widely and no alert was put out to surgeons and patients.

Cohen says device regulation is not fit for the purpose and is in need of radical change. She quotes Nick Freemantle, professor of clinical epidemiology and biostatistics at University College, London: “Why is it that people are afforded different levels of protection depending on whether they have a heart attack, diabetes, or a hip replacement in their old age? the methods of device regulation seem to be more from the 1950s than the 21st century”.

New Zealand’s Health Ministry has been silent on the subject, leaving it to DePuy and surgeons. Consequently, some patients are still in the dark.

By Phil Taylor | Email Phil

Hip patients: Why weren’t we told?

Doctors urge against metal hip joints

British experts at the world’s biggest artificial joint registry said doctors should stop using metal-on-metal hip replacements, citing an analysis showing they have to be fixed or replaced more often than other implants.

All metal hip joints were already under scrutiny over questions about how long they last, and one major manufacturer recalled its product over a year ago. Last year, regulators in the U.S. asked makers to conduct safety studies on them. most artificial hip joints are plastic or ceramic.

Earlier this month, the British agency that regulates medical devices warned that patients with these joints should have yearly blood tests to make sure no dangerous metals are seeping into their bodies. it also advised patients with symptoms such as pain, swelling or reduced movement to get MRI scans to check for muscle damage in case the joints need to be removed.

In the new study, experts analyzed data for more than 400,000 hip replacements from the National Joint Registry of England and Wales between 2003 and 2011. More than 31,000 of those were metal-on-metal devices.

After five years, about 6 percent of people with the metal-on-metal variety needed surgery to fix or replace them. that compares with just 1.7 to 2.3 percent of people who had ceramic or plastic joints.

Doctors usually expect hip joints to last at least a decade. the study was published online Tuesday in the journal, Lancet. it was paid for by the National Joint Registry.

Ashley Blom, head of orthopedic research at the University of Bristol and one of the study authors, emphasized most people with a metal hip haven’t needed a replacement. But with so many alternatives, he said there was no reason to take that risk.

“If I were a patient, I would not choose a metal-on-metal hip,” he said.

He said the rates of failing metal hips were likely an underestimate since not all patients report their symptoms or have surgery to fix the problem.

In 2010, DePuy, part of Johnson & Johnson, recalled a metal hip implant after it was linked to high failure rates. Blom said the new analysis suggests the problem applies to all metal-on-metal hips, not just one brand. Doctors began using metal-on-metal implants after laboratory tests suggested the devices would be more resistant to wear and reduced the chances of dislocation. They aren’t sure why that isn’t the case once they are used in patients.

Last year, the U.S. Food and Drug Administration asked all manufacturers of metal-on-metal hips to conduct safety studies. use of the devices has dropped dramatically in recent years worldwide. in the U.K., only about 5 percent of patients are believed to be getting the metal hips.

In the U.S., estimates are about 500,000 people have them.

Some experts called for tighter regulation, warning there might be similar problems with other joint replacements, such as those for knees and shoulders.

“I wouldn’t be surprised if this was just the beginning of the storm,” said Art Sedrakyan, an associate professor of public health at Weill Cornell Medical College in new York, who authored an accompanying commentary in Lancet. “A lot of products have been allowed onto the market without clinical evidence they work.”

Doctors urge against metal hip joints