DePuy ASR Hip Implants
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Overview
Following international concerns about the high failure rate of DePuy ASR (Articular Surface Replacement) hip implants and the global recall of these artificial hips by manufacturer DePuy Orthopaedics in August 2010, huge numbers of people have been identified with problematic implants. The recall process in Ireland has been progressing with patients being called back for x-ray examination, consultation with their surgeon and metal ion blood testing and at time of writing in February 2011, metal ion blood results are now being communicated to patients. Regrettably, many clients of Cian O’Carroll Solicitors are not receiving any explanation of what the problem with their hip implant is. Nor is the metal ion blood testing being explained with the effect that patients are worried and even fearful of what all this means for them. |
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The science behind the defective DePuy hip implants is still emerging with studies on different aspects of the defects progressing in several countries. Searching the internet for information yields very little hard science. Many websites offering information seem more interested in scaring patients than informing them while available scientific papers are highly technical and difficult to understand.
What is wrong with the DePuy ASR hip implants?
The DePuy ASR implants, whether hip resurfacing or the total hip replacement, were designed in a way that unintentionally made them likely to wear much more than they should. The metal cup into which the metal ball of the artificial hip fits is believed to be the more defective component. It was designed to be less than a full hemisphere so that the operation to fit it in the patient’s hip would be less invasive. The larger the cup, the more hip bone must be removed to allow it to be fitted.
Studies have shown however that because the DePuy ASR cup covers a smaller surface area of the ball, it has required a highly precise alignment between ball and cup to ensure that uneven pressures do not arise when the patient is using the hip joint in normal movement. Where this alignment is not precise, and such precision is often not possible due to various surgical and anatomical reasons, the ball and cup wear off each other excessively. This wearing leads to two problems.
How many are affected?At present, studies are looking at patients who have had these DePuy ARS hip implants for little more than 5 years. The implants have been in use since April 2003 so the available statistics are lagging behind what could be described as a true timeline. Nevertheless, it is clear that these implants are highly problematic. The only clear studies of reported failures of the implants come from abroad, the UK and Australia where each patient is monitored on an ongoing basis. Such studies are highly desirable but are not conducted in Ireland where a huge number of these devices have been implanted – some 3,500 in total. In those foreign studies, it was noted that up to 2009, 1 in 8 patients required further surgery due to adverse metal reactions in the first 5 years alone and it is reasonable to assume that that proportion will rise significantly over following years.
In Ireland, no such figures are available but from 100 or more clients of this firm who have had these implants, it is clear that many have been complaining of problems for some years without having their complaints adequately addressed.
Symptoms of failure
Typically, patients have complained of pain in their hip or groin, a feeling of looseness, clicking or grinding in the joint, leg length difference leading to limping and in extreme cases, dislocation of the hip, fracture or loss of use of the affected limb. Patients have been found to have large accumulations of fluid in the area of the hip which while not septic (no bacteria are infecting the area), their immune systems have reacted to the implant or metal debris wearing from it causing damage to the bone and soft tissues at or close to the affected hip.
The Blood testPatients have typically been given a blood test to analyse the levels of cobalt and chromium ions in their blood. These tests are indicative though not conclusive of the levels of those metals in the vicinity of the hip implant. To accurately analyse the levels at the joint, fluid must be removed or ‘aspirated’ from the joint area.
It is regrettable that the practice to date has not been to inform patients of the actual levels but merely to interpret those levels. The absence of transparency in this testing process is from a legal perspective unsettling. Patients, having submitted voluntarily to testing by or on behalf of DePuy should be informed fully of the results. I would advise all affected patients to insist on being given a copy of the laboratory report on their testing to ensure open and transparent reporting of these results which may impact enormously on the health and wellbeing of patients.
Elevated levels of cobalt and in particular chromium ions in a patient’s blood are indicative of a high risk of adverse reaction even in the absence of pain or other symptoms. These levels tend to be at their highest in the first two years after surgery and damage caused at that time can lead to serious medical complications later on.
What compensation are patients entitled to?
For patients affected by the recall, most if not all will require legal advice. While many patients will not require further surgery, many will and many others may suffer some level of pain, discomfort or other harm associated with the defective implants. For others fortunate not to suffer any harm, they will still have the worry of knowing that their implant is defective and may yet cause them harm and of course most patients will have to be monitored over following years for implant performance and metal ion levels.
Irish law is clear on what these affected patients are entitled to. The Liability for Defective Products Act makes clear that the supplier of a defective product is responsible for all pain, suffering or other loss caused to a person as a result of the defective product. While to date DePuy Orthopaedics have only offered affected patients free medical care and expenses, Irish law will oblige them to pay substantial damages to anyone injured by the implant. For many this compensation will run to six figure sums given the magnitude of the harm that they have suffered
The DePuy ASR implants, whether hip resurfacing or the total hip replacement, were designed in a way that unintentionally made them likely to wear much more than they should. The metal cup into which the metal ball of the artificial hip fits is believed to be the more defective component. It was designed to be less than a full hemisphere so that the operation to fit it in the patient’s hip would be less invasive. The larger the cup, the more hip bone must be removed to allow it to be fitted.
Studies have shown however that because the DePuy ASR cup covers a smaller surface area of the ball, it has required a highly precise alignment between ball and cup to ensure that uneven pressures do not arise when the patient is using the hip joint in normal movement. Where this alignment is not precise, and such precision is often not possible due to various surgical and anatomical reasons, the ball and cup wear off each other excessively. This wearing leads to two problems.
- The first is that the metal implants can be eroded or deformed by the normal pressures of carrying the weight of the patient.
- The second is that the metal that wears off can cause a reaction in the immune response of the patient leading to inflammation and damage to the hip of the patient and in many cases a build up or “pseudo tumour” that not only damages the bones at the hip but can also damage the muscles and tendons on the area of the hip.
How many are affected?At present, studies are looking at patients who have had these DePuy ARS hip implants for little more than 5 years. The implants have been in use since April 2003 so the available statistics are lagging behind what could be described as a true timeline. Nevertheless, it is clear that these implants are highly problematic. The only clear studies of reported failures of the implants come from abroad, the UK and Australia where each patient is monitored on an ongoing basis. Such studies are highly desirable but are not conducted in Ireland where a huge number of these devices have been implanted – some 3,500 in total. In those foreign studies, it was noted that up to 2009, 1 in 8 patients required further surgery due to adverse metal reactions in the first 5 years alone and it is reasonable to assume that that proportion will rise significantly over following years.
In Ireland, no such figures are available but from 100 or more clients of this firm who have had these implants, it is clear that many have been complaining of problems for some years without having their complaints adequately addressed.
Symptoms of failure
Typically, patients have complained of pain in their hip or groin, a feeling of looseness, clicking or grinding in the joint, leg length difference leading to limping and in extreme cases, dislocation of the hip, fracture or loss of use of the affected limb. Patients have been found to have large accumulations of fluid in the area of the hip which while not septic (no bacteria are infecting the area), their immune systems have reacted to the implant or metal debris wearing from it causing damage to the bone and soft tissues at or close to the affected hip.
The Blood testPatients have typically been given a blood test to analyse the levels of cobalt and chromium ions in their blood. These tests are indicative though not conclusive of the levels of those metals in the vicinity of the hip implant. To accurately analyse the levels at the joint, fluid must be removed or ‘aspirated’ from the joint area.
It is regrettable that the practice to date has not been to inform patients of the actual levels but merely to interpret those levels. The absence of transparency in this testing process is from a legal perspective unsettling. Patients, having submitted voluntarily to testing by or on behalf of DePuy should be informed fully of the results. I would advise all affected patients to insist on being given a copy of the laboratory report on their testing to ensure open and transparent reporting of these results which may impact enormously on the health and wellbeing of patients.
Elevated levels of cobalt and in particular chromium ions in a patient’s blood are indicative of a high risk of adverse reaction even in the absence of pain or other symptoms. These levels tend to be at their highest in the first two years after surgery and damage caused at that time can lead to serious medical complications later on.
What compensation are patients entitled to?
For patients affected by the recall, most if not all will require legal advice. While many patients will not require further surgery, many will and many others may suffer some level of pain, discomfort or other harm associated with the defective implants. For others fortunate not to suffer any harm, they will still have the worry of knowing that their implant is defective and may yet cause them harm and of course most patients will have to be monitored over following years for implant performance and metal ion levels.
Irish law is clear on what these affected patients are entitled to. The Liability for Defective Products Act makes clear that the supplier of a defective product is responsible for all pain, suffering or other loss caused to a person as a result of the defective product. While to date DePuy Orthopaedics have only offered affected patients free medical care and expenses, Irish law will oblige them to pay substantial damages to anyone injured by the implant. For many this compensation will run to six figure sums given the magnitude of the harm that they have suffered
