Metal on Metal Hips – Patient Advice
We understand that people will be deeply worried by the stories that have appeared in the Sunday newspapers about total hip replacements and cancer. If you need specific advice about the type of hip replacement you have had or if you just want to speak and get advice then please see your general practitioner who may refer you back to your surgeon for a longer discussion.
BOA/BHS Information to patients about newspaper reports on Cancer and Total Hip Replacements
We have put some information together for you about cancer and total hip replacement. Most patients do not have hip replacements with metal on metal bearings so that a metal ball rubs against a solid metal or metal lined socket (a metal on metal bearing): Only 1 in 6 (15%) of hip replacements recorded in the National Joint Registry are metal on metal.
Two studies were discussed at the British Hip Society in Manchester (March 1-2, 2012) one of which has been reported in the papers. A study performed in Bristol has been reported on the 4th of March, 2012 in the Sunday Times and Telegraph.
The report on 71 patients with metal on metal surface hip replacements found abnormalities in cells lining the bladder in 15 patients which are not fully understood, but the suggestion is that these cell changes may, in very few patients and over long periods of time, lead to cancer. One patient in this study was found to have an early bladder cancer and we are not certain that this was caused by their hip replacement.
A second research project was presented from Newcastle that showed NO increase in the number of patients presenting with bladder cancers in 723 patients with metal on metal hip replacements compared to 2,016 with hip replacements where the ball is metal but the socket is plastic. These patients had been followed up for much longer than the previous study for between 6 and 14 years. This study was not mentioned in newspapers despite the fact that it did not show any link with cancer.
Neither of these studies have been scrutinised by experts to see if the information provided is sound and conclusions are correct. This is a process that all scientific papers go through before they are published in a scientific journal and before the observations made can be verified as true with certainty and any subsequent actions recommended.
1. Many studies have shown that people with hip replacements tend to live longer than people who do not have hip replacements. This may be for many reasons. For instance, people who have surgery to increase their mobility may be fitter than the general population.
2. Roughly 5% of people will have had a diagnosis of cancer before they have a hip replacement and roughly 8% will get cancer afterwards. Not because of the hip replacement but because cancer gets more common as we get older anyway. It is against this background that any potential increased risks are assessed.
3. Population studies have shown that people tend to live longer after hip replacement and the rates of cancers are different. For instance, people with hip replacements have less lung cancer, less cancer of the stomach and colon but may have slightly more cancer of the bladder and melanoma of the skin. This is found in studies of tens of thousands of people, followed over very many years, some over twenty years.
4. There are several factors that increase the risk for bladder cancer and the most important is probably cigarette smoking.
5. A study in Finland by Visuri has looked at mortality after metal-on-metal (metal socket) and metal-on-polyethylene (plastic socket) Total Hip Replacements in Finland. They studied 2,164 patients over 16 years. Both bearing surfaces had lower overall mortality than the normal population.
6. The National Joint Registry collects information on all patients having joint replacements and has done so since 2003. Provisional and early analysis, which is still ongoing, indicates that when compared with traditional hip replacement, the many thousands of patients with a metal-on-metal hip replacements did not have an increased risk of a cancer treatment in the seven years after surgery. This information has not yet been checked by independent experts.
The follow-up of patients with metal on metal hip replacements is still short and we cannot therefore say if there is an increased risk in the longer term of 10-30 years.
The British Orthopaedic Association and the British Hip Society, the National Joint Registry, the MHRA and Department of Health are all working together to understand more about this. Even as we write there is more research being done to make sure that we have the best possible evidence on which to base advice for our patients and surgeons.
Currently there is no verified evidence that having a metal on metal hip replacement increases cancer risk. It would be unwise to suggest removing these joint replacements and taking additional risks of surgery just on the possible risk of cancer.
More information will be available in the next few weeks and we suggest that we wait for the outcome of further investigations of larger studies.
If you are anxious please discuss this with your treating doctors.
Far from participating in a “large uncontrolled experiment” as described in the media the British Orthopaedic Association (BOA), the National Joint Registry and the MHRA have been working closely together in looking after our patients by identifying the problems relating to Metal on Metal Hip Replacements, highlighted by yesterday’s updated published advice to surgeons.
It is important to understand that the move from a traditional hip replacement with a metal head and plastic socket was intended to benefit young patients. This was because the traditional implant was more likely to fail over time and require a complex revision operation. All the initial evidence suggested that changing the bearing surface to Metal on Metal could help the artificial joint to last longer. No manufacturer deliberately sets out to design a bad implant for patients.
The information on failures of Metal on Metal implants accumulated slowly – as is always the case – but came to a point when, based on Joint Registry data in Australia and the UK, one implant in particular – De Puy’s ASR system – was identified as performing significantly less well than others used to replace painful arthritic hip joints. The BOA brought this to the attention of the MHRA, helped provide senior and expert clinical input into the Expert Advisory Group on Metal on Metal Implants, and addressed the question of how to monitor implants introduced by forming the Orthopaedic Devices Evaluation Panel.
The Expert Advisory Group triggered the first MHRA ASR alert in 2010 and has been continually reviewing Joint Registry data since then. From the further data accumulated on stemmed large head Metal on Metal articulation it was appropriate that our advice to hip surgeons was updated now in the form of a further MHRA alert.
As our members conduct over one million orthopaedic operations each year in England alone, the BOA takes its responsibilities to patients extremely seriously. We helped to develop the advice to clinicians and formulate the initial MHRA alert on the ASR, asking that patients are seen each year and investigated for the metal Cobalt and Chromium in their blood. We have also recommended using an MRI scan to look for changes in the tissues, including those muscles round the hip replacement that may indicate the body reacting to the presence of metal debris released by metal ball of the hip rubbing on the metal cup.
Earlier this year we wrote to the Chief Executive Officers of each Trust and all orthopaedic surgeons reminding them of their responsibility to follow up all patients with ASR Metal on Metal Implants.
Following the earlier ASR alert the BOA, with the MHRA, have worked in briefing all relevant parties on the problems with CE marking and suggested ways of improving post market surveillance, to use Patient Reported Outcomes Measures data and other ways of identifying failing implants earlier, and suggesting methods of safer introduction of implants. This culminated last November in an international conference (attended by the US FDA, Care Canada and others), jointly led by the BOA and MHRA, to develop an initiative called “Beyond Compliance” that is currently being considered by the Department of Health.
In all our work we are guided our motto of ‘Caring for Patients, Supporting Surgeons’. We take pride in the quality of the care that we deliver, we promote excellence in surgical practice through continuous improvement and critical review of our outcomes. Accordingly we are working hard with partners, including the National Institute for Health Research and Arthritis Research UK, to enhance considerably the amount of funding available for trauma and orthopaedic research – precisely to focus on even better on improving our treatments and delivering safer outcomes that transform our patients’ lives.