Metal on Metal Hip Replacements, Resurfacing and Issues:

A Guide

There has been intense media coverage, some of which has been misleading, in respect of metal on metal hip replacements. 

In this page I will try to give some perspective and advice to those who have had such a replacement.

Metal on Metal Hips 

The MHRA, the organisation in the UK which regulates medical implants issued an alert in respect of all metal on metal hip replacements on the 28th February 2012.

Within this they have made recommendations with respect to ALL metal on metal hip replacements.

This is regardless of manufacturer and  includes all head sizes.

Specific recommendations have been made with respect to the monitoring and investigation of all patients.

 In the case of some impants this depends on whether patients have symptoms or not.

The alert refers to patients as being either "Asymptomatic" or "Symptomatic"

"Asymptomatic" patients would have little or no discomfort or pain, good function in their hip and feel as if their hip were normal or completely normal.

"Symptomatic" patients may feel discomfort, perhaps and ache, pain with exertion or symptoms that come on with certain activities, or a range of symptoms right up to severe pain.

If you are not certain at all about what you experience with your hip and whether it is normal or abnormal, or whether it relates to your hip or to something else, then it would be best to speak to your General Practitioner who can discuss with you whether your experience is what would be expected or not.

Many patients with metal on metal replacements are asymptomatic and if this is the case, although some patients require yearly review, the level of monitoring required is far less.

The level of monitoring you may require should you have a metal on metal hip is entirely dependent on the type of hip or resurfacing you have received and you or your GP will need to check this with your surgeon.

Regardless of which hip you have, should you develop symptoms you should bee seen by an Orthopaedic surgeon.

The full details of the alert and guidance can be found on the MHRA website at the address below. Please click on the link  and follow the link to the Guidance PDF:

http://www.mhra.gov.uk/Publications/Safetywarnings/MedicalDeviceAlerts/CON155761

At the end of the guidance is a table which breaks down the various types of implants as well as the recommendations for further monitoring.


What Should I do Next?  What kind of hip do I have?

It is likely that you will be very anxious. Some of the television programmes and newspaper articles have been disturbing.

The cases presented have been extreeme and there is nothing to suggest that what has been "reported" will happen to every metal on metal on metal hip. 

Indeed many individuals have very well functioning hip replacements that are likely to last them the rest of their lives.

This was of course the objective when the hip was implanted.

The MHRA recognises this and this is why they have divided patients into "Asymptomatic" as well as "Symptomatic" groups. You will notice they have stated this at the beginning of their alert.

But what kind of hip do you have?

There are a number of ways you can find out.

  •  Contact your General Practitioner who can enquire on your behalf. There is no need for an emergency review and it is very likely that the hospital at which you had your surgery will be putting systems in place to recall you if you did have a metal on metal hip. 

  • If your surgery was performed privately your surgeon will be able to tell you straight away what was implanted and you should contact your surgeon directly through the hospital where you recieved your surgery or by ringing his private secretary.

  • If your surgery was performed on the NHS you should contact the hospital where you had your surgery and they will be able to advise you which implant you have had implanted.  They will also be able to advise you of the steps being taken with respect to ongoing follow up.
It is easy to say not to worry but your surgeon will appreciate that you are anxious and want answers.

Your surgeon will be able to offer you advice, ensure that you are investigated correctly and tell you what the results of your investigations mean.

There is no reason for any rushed decisions and you and your surgeon should discuss matters fully. 

It is worth considering that for your surgeon there are are some questions that, at this time, cannot be answered as advice is still being issued.

As with the ASR hip detailed below further guidance and advice is likely to emerge from the British Orthopaedic Society in conjunction with the British Hip Society.

You and your surgeon should come to a solution based on your symptoms, any investigations and after a full consideration those.

The ASR Hip

The ASR hip system was produced by a company named DePuy a subsidary of Johnson & Johnson.

It gave surgeons the option to perform either a resurfacing (ASR) of the hip or place a large diameter metal head on top of a conventional hip replacement stem (ASR XL). 

The objective of either option was to try and prolong the lifespan of the hip replacement in a young or active adult.

It is well known that metal on polyethylene hip replacements have a finite lifespan and the use of metal on metal is an attempt to make the hip last longer.

Another advantage was the stability of the large head. 

The larger the head the more stable (less likely to dislocate) the hip becomes.

With both resurfacing and the XL heads the size of the head is the same as, or nearly the same as, the normal hip. This is a great advantage to the patient.


The ASR recall? What does it mean?

In the case of the ASR early revision rates appeared unacceptably high in some surgeons' patients.  This has been very variable and appears very dependent on which surgeon has implanted the hip.

The rates for revision have been as high as 50% in some surgeons' cases and as low as 4% in others.

For this reason and the highly variable outcomes the hip system has been withdrawn and all patients with it will need to be reviewed for life.

It is not the place of this site to delve into the process as to why this is the case and there are a number of theories as to why it occurs.

A recall was issued by the MHRA - the body which governs implants and their use - in late 2010. 

The British Orthopaedic Association, the British Hip Society and Depuy have since agreed that all patients who have received the ASR should recieve the following process of treatment.

The process is given as advice to surgeons and is not meant to be exhaustive but informative and in reality each individual patient should be considered as an indivuidual.

The advice previously issued has now been updated by the MHRA with the advice found at the link above.

Patients should be contacted by their treating surgeon or hospital and and arrangement made for an out-patient consultation.

During the consultation your surgeon can explain which investigations need to be undertaken and arrange them for you as well as further follow ups to discuss the results


What Tests are There?

The recommendations refer to a blood test and possibly imaging either an MRI or an Ultrasound.

The blood test is to look for levels of metal ions and specifically for those of Chromium and Cobalt.

These are consituents of the type of metal used to make the hip replacement system. If there is excessive wear then small amounts of metal (ions) are released around the hip. These then enter the blood stream.

This does not mean there are pieces of metal floating around the body and it does not mean that pieces of metal are lying all around the soft tissues of the hip. The metal is at a molecular level.

Indeed within your blood sream there is already metal, most of which is essential to keeping you alive, such as the Iron that transports the oxygen to your tissues. 

However we do know that locally high levels of metal ions can lead to changes in the soft tissues around the hip. 

For this reason further imaging such as Ultrasound and MRI can be useful to look a the soft tissues and to assess for fluid collections and soft tissue changes. 


What does the blood test mean?

The MHRA website talks about levesl of metal ions at 7ppb (parts per billion). This equates to a blood level of 119 nmol/ml of Cobalt and 134.5nmol/ml of Chromium.

These levels merely refer to the number of molecules of these metals in your bloodstream.

In itself these levels mean nothing specific but help the surgeon to decide how to monitor you.

They certainly do not mean that having these metals in your bloodstream means that you have blood poisoning.

The levels need to be taken into consideration together with the results of other tests if appropriate and you will see that the MHRA state that. 

Your surgeon will arrange the most appropriate test according to availability locally and all results need to be looked at together with a review of any symptoms you may have.

The blood tests merely act as an aid to the surgeon and it is possible to have normal blood tests but severe symptoms.

The blood test may need to be repeated at a period of time and reviewed by your surgeon.

For that reason having normal blood tests does not mean that there is no problem. However in the face of a blood test that were rising or changing your surgeon can see a trend that may help them make decisions about what is right for you on an individual basis.


What does it mean when it says "Revision"?

This means removing the old components and replacing them with different ones.

In the case of a resurfacing this means removing the old cup, cutting the neck of the thigh bone as would normally be done for an ordinary hip replacement and putting in and ordinary hip replacement.

In the case of an ASR XL head, already on a normal hip replacement, this means removing the old cup and putting in a new cup with a new head on top of the old stem.

Consideration would need to be given to what to replace the metal on metal bearing with.

You should discuss options with your surgeon.


How long will I need to be followed up if I have a Metal on Metal hip?

The recommendations are now that patients with metal on metal hips will need to be followed annually for the lifetime of their prosthesis if they have an ASR hip or a head size equal to or above 36mm on a stem.

For those patients who have a resurfacing system other than the ASR, or who have a metal on metal hip with a head size less than 36mm the recommnedations are for an annula review IF the patient is symptomatic and otherwise according to the local protocol.

However patients symptoms may change at any point and surgeons should continue to investigate their patients accordingly.

If you go on to have the components revised you woud not be followed up any longer than would be normal for a revision hip procedure.


What if my hip starts to hurt in several years time?

The MHRA alert now means that all metal on metal bearings will be reviewed if they are symptomatic. If you develop symptoms in the future but were previsouly well then you should contact your GP who will arrange for you to be reviewed by an appropriate surgeon.

All implants have a failure rate and with time all implants will come to revision. 

The hope with metal on metal replacements is that this would take a very long time because of the hard nature of the bearing surface.

However many factors can lead to a joint replacement failing and therefore some patients with a metal on metal hip would find that their hip will fail eventually.

If you have any symptoms you should contact your GP. Your GP will be able to find out for you which hip system has been used.

It is likely that the same process outlined above would be followed and together with your surgeon a decision can be made about how best to proceed for you next.


Is the ASR system still in use?

The ASR system was withdrawn from the market at the time of the recall and can no longer be used.

If you have had a hip replacement since the time of the recall - October 2010 onwards - you are not likely to have had an ASR resurfacing or an ASR XL head.


Are other metal on metal hips still in use?

There are a number of other Resurfacing as well as metal on metal hip replacement systems still available to surgeons in the UK health system.

It is likely that certain patients would benefit from such replacements.

You should discuss which implant you have had and if you are considering hip replacement which implant is to be used.


What might be the symptoms I would experience?

Usually the symptoms are of pain and stiffness

The pain can be minor initially but over a period of time it becomes more intense. It is usually located to the groin or around the hip but sometimes down the thigh.

Some patients experience grating or grinding. This is an unusual symptom but can occur without pain. If you were to experience this then you should see a surgeon. 

As time goes on more symptoms may be linked to metal on metal hips however at this time these are the main ones


Will I get Cancer? The papers have said that the metal is linked to cancer?

In extremely high levels of industrial exposure the metals concerned, Chromium and Cobalt, have been linked to cancers.

However these have either been through inhaltion, or through exposure to such metals through high levels in drinking water.

Such exposure has occurred over prolonged periods of time

The following link gives a full update on all the available evidence about metal on metal hips and cancer

http://www.bmj.com/content/344/bmj.e2383


What do I do  if I have an ASR Hip or resurfacing?

Depuy have agreed to formally fund all patients who require further surgery as well as fund their long term review.

More information about this can be obtained from their website below

http://www.depuy.com/ukasrrecall

If you have an ASR resurfacing or an ASR XL head hip then you should register with DePuy through their website.

If you know that you have an ASR hip you should follow the registration process to generate a claim reference number. 

This will allow your surgeon and hospital to discuss your case with De Puy and for you to liaise with them more clearly.


What do I do if I do not have an ASR and need further surgery?

Other manufacturers have not as yet made comment about their implants. This would include Birmingham hip replacements from Smith and Nephew, Durom From Zimmer, Cormet from Corin among many others.

There has been no suggestion that any of these implants have a significant issue  at all and indeed there is evidence to support their use.

It is likely that their manufacturers will in the future make some comment and issue guidance with respect to their implants given the level of concern as well as media interest.

At this time there is no clear guidance for your surgeon as to how to discuss this with you or direct you, other than to follow the guidance from the MHRA.

If you are concerned at all about your hip replacement, resurfacing or large diameter metal replacement it would be best for you to speak to a surgeon who undertakes regular revision hip surgery. 


I'm really quite scared about this and do not know what to do?

This is quite understandable. The articles in the press may have caused you to become quite alarmed.

However nobody is trying to cover this up and you are actively encouraged to see a surgeon. We as surgeons are bound to follow you and monitor you.

At any time your symptoms, if they change, can be reviewed and you do not need to wait or live in fear.

You will no doubt be anxious, concerned perhaps even angry. 

You can consult your GP and they in turn can refer you back to your surgeon or, you can consult your surgeon directly in the private sector.

No decisions need to be made in haste and you should take as much time as necessary with your surgeon to discuss the options.

Revision surgery is major surgery and carries significant risks. 

There is no need to rush into it and you should take time to consider it. 

Clearly if you have alot of symptoms the choice is easier to make. 

Your surgeon will be able to guide you with the aid of the  investigations.

It is very difficult to provide the answer to every question in this page and there may well be others you will have.

If you have further queries following this we would be happy to discuss them further with you. You can arrange this 

  • by speaking to my secretary on 01604885009 or 
  • via e mail through the contact section of the website.