Chromium and Cobalt Poisoning: What are the Long Term Side Effects of Metallosis?

It is likely that the recipients of a metal-on-metal hip implant have heard about the possible consequences from the metal shavings which can be released into the body when the metal cup and ball rub against one another during normal activities. Tiny ions of cobalt and chromium shear off when the two surfaces meet and those ions can lodge in the surrounding tissues or can end up in the bloodstream. As more and more metal hip implant patients are realizing the seriousness of metal toxicity, blood testing for elevated levels of metals is increasing. In many cases patients have been found to have levels of cobalt and chromium in their bloodstream which are as much as a hundred times normal levels. 

Although slightly elevated levels of these metals are fairly normal for patients with metal-on-metal hip implants, extreme elevations can be very dangerous—and anxiety-producing for the patient. DePuy released a report indicating that concentrations of the metals greater than 7 parts per billion are cause for concern. The Mayo Clinic has set somewhat different reference values, stating that blood serum concentrations of chromium greater than 1ng/mL suggests significant wear of the metal implant while serum concentrations greater than 5.0 ng/mL of cobalt can be considered toxic and also suggest significant wear of the prosthesis. Remember that 1 PPB (part per billion) equals 1.0 ng/mL.

For DePuy plaintiffs - and our legal team - Ohio is the place to be.

By Independent Staff Writer
Two weeks ago, the U.S. Panel on Multidistrict Litigation conducted a hearing to discuss where the DePuy Hip Implant MDL should be placed. Today, the Panel announced that the litigation will take place in the Northern District of Ohio.

Complaints about the DePuy ASR hip implants have been reported throughout the United States, which prompted a hearing to consolidate the cases into multidistrict litigation. Counsel for DePuy Orthopaedics, Inc. did not object to doing so. The Multidistrict Litigation (MDL) Panel determined that the DePuy cases qualified for consolidation and created DePuy Mulitdistrict Litigation.

There were many different courts in the running for the federal district in which the pretrial proceedings would take place, including Kentucky, Indiana, New Jersey, Ohio, and Florida. Counsel for DePuy and several Plaintiffs' lawyers who represent people harmed by the DePuy devices submitted arguments to the Panel as to which court they felt was most appropriate for these cases.

As we've explained in previous articles, consolidating a case conserves resources for the attorneys as well as the judiciary, and bringing individual lawsuits for each case can make the costs so prohibitive as to present an obstacle to getting a fair settlement for the plaintiffs. The fact that DePuy Multidistrict Litigation has been formed creates a more efficient way for our legal team to pursue claims for our clients and ensures we are better able to give them the individual attention they need.

The ASR Acetabular System falls far short of other total hip replacement systems. Here's how.

By Independent Staff Writer

In a previous article we wrote on bone deterioration, we discussed how the bones of your hip are constructed and how a hip implant strives to mimic the qualities so that you can maintain a normal range of movement and a fairly active life.

In this article, we'd like to show you how the ASR XL Acetabular System was constructed - and why it fell so short of what hip implant patients needed to give them back their previous quality of life.

What a Hip Implant is Up Against

Any hip implant is going head-to-head against the natural construction of your body, which is no easy feat. What we think of as our hip is actually two bones: the acetabulum (also called the hip socket) and the femoral head, which is the rounded top of your femur (the main bone that runs the length of your thigh).

As you can see, the two bones of your hip are actually attached to each other securely by two ligaments. The shorter ligament at the center of the femur head is the transverse acetabular ligament, while the longer ligament that runs from the ilium down to the femur itself is the iliofemoral ligament.

These ligaments, along with the cartilage surrounding the hip joint, are the reason your hip doesn't dislocate on a regular basis. The iliofemoral ligament in particular is extraordinarily strong - in fact, the strongest ligament in the human body - and when you are standing or sitting, this ligament flexes or releases to allow a range of movement without letting the hip move out of the socket.

For its part, the transverse acetabular ligament and the surrounding cartilage make up the acetabular labrum, whose purpose is to deepen the hip socket so that the head of the femur can't slip out. The deeper the hip socket, the more secure the femur bone becomes and the less likely your hip will dislocate.

When your natural hip is removed to make way for a hip implant, neither of those ligaments is in place, and the cushion of cartilage is removed to make way for an artificial replacement. Removing the labrum means that your hip is 92% more likely to suffer contact stresses and 40% more likely to allow the femur and acetabulum to touch.

As you can see, your hip is a sophisticated and well-constructed mechanism, and it is extremely difficult to create a man-made replacement for it. Let's take a look at some of the best attempts available in the form of conventional hip replacement and total hip replacement systems, including the ASR Acetabular System. 

Women have a disproportionally larger number of problems with hip implant surgery than men do. Especially with the ASR XL Acetabular System.

By Independent Staff Writer

Several news sources, among them the New York Times, have already commented on the mounting data that more women than men are reporting problems with the ASR XL Acetabular System. We'd like to explain exactly why that is.

Problem: Hip Implant Not Designed Ideally for Wider Hip Sockets

Women, as you may have heard, are structured differently anatomically than men. The differences aren't merely on the surface, however; they extend into the skeletal structure and particularly in the pelvis region. Women have wider hips with bigger hip sockets to accommodate the process of giving birth, which means they often have more problems in hip implant surgery because those large hip sockets allow the implant to dislocate more easily.

In the DePuy ASR XL Acetabular System, however, the problems go beyond the norm. One of the reasons is that the hip implant was designed to be extremely shallow, exacerbating the problems women already have with hip implants.

Problem: Women More Likely to Require Hip Implants

Women are more prone to osteopenia, osteoporosis, and often have weaker bones overall than men, particularly as they age. The onset of menopause, and the subsequent drop in estrogen, have been linked to rapid bone deterioration. Because of all of these factors, women are more likely than men overall to require a hip implant because of a hip fracture.

Problem: Small, Shallow Hip Implant

The DePuy ASR XL Acetabular System was designed to give patients a greater range of motion. If you'll recall, the design of the hip implant included two parts: an implant inserted into the femur bone with a rounded top that fit into a cup placed in the hip bone.

In the design of the ASR XL Acetabular System, the cup was made very shallow, which meant that the patient could move their leg in a wider arc before the other part of the implant might dislocate.

Good in theory. And if DePuy had tested their product properly, it might have worked quite well. In real life, it went a little differently.

The shallow hip implants meant that all of the friction caused by everyday movement was focused on a much smaller area. There was more force on a smaller amount of material. The hip implant was under more stress and was more prone to the friction that caused small metal ions to break off into the bloodstream. It was also more likely to break altogether.

Especially in women. Their smaller, shallower hip implants meant there was even more strain on the material. Women who have an ASR XL Acetabular System are reporting problems in greater numbers than men in part because their hip implants are simply breaking down faster. They have the same problems, forced upon a smaller area.

Our consulting doctor offered some sobering statistics for smaller hip implants in general: the risk of a hip revision surgery for a hip implant with a head size of 44 mm is five times that of a hip implant with a head size of 55 mm.

Many patients who received a DePuy hip implant have suffered heavy metal poisoning. But what does that really mean?

By Independent Staff Writer

As we try to describe the reasons the DePuy ASR XL Acetabular System present such a danger to your health, we occasionally use terms you may be only vaguely familiar with. This is an ongoing series of articles on the medical terms related to the DePuy hip recall and hip revision surgeries.

Heavy metal poisoning, by its strictest definition, is simply the build-up of heavy metals in the soft tissues of the body. It is also referred to as heavy metal toxicity. The most common heavy metals associated with poisoning are lead, mercury, arsenic, and cadmium; the ones that are in the structure of the DePuy ASR XL Acetabular hip implant are chromium and cobalt.

One doctor who analyzed several patients who were tested for metal poisoning said that these were some of the highest levels for chromium and cobalt ions he has ever seen. Despite this, he also said that many of the patients had no symptoms, which makes for a very good argument that any patients who received an ASR XL Acetabular System should be monitored closely and receive regular blood tests.

For any kind of heavy metal poisoning, the symptoms largely revolve around the digestive system: nausea, vomiting, diarrhea, and stomach pain, for example. Patients may also have headaches or get a metallic taste in their mouths. In extreme cases, heavy metal poisoning may make patients lose cognitive, motor, and language function.

Too many ASR XL Acetabular Systems causing problems in first three years.

By Independent Staff Writer

In 2003, DePuy released the ASRTM XL Acetabular System, a hip implant that was touted to last up to 20 years with a stronger, more durable metal-on-metal design. Approximately 93,000 people around the world weighed the risks of surgery against their current level of pain and discomfort and chose to receive a hip implant that they believed would give them 15 to 20 years of pain-free movement.

DePuy issued a hip recall earlier this year, which means a disturbing number of those patients will likely have to undergo a hip revision surgery-years ahead of schedule. 

With a typical hip replacement, the patient is able to resume a normal life after three to six months of recovery. There are a number of "common" problems, such as loosening joints, fractures, and occasionally dislocation. Hip implant recipients are informed beforehand that the risk of these types of failure is .5-3%

The admitted failure rate of the ASR XL Acetabular System is 13%-meaning, this is the number acknowledged by DePuy. Mounting evidence suggests that the failure rate is higher than that, especially if one doesn't limit the definition of "failure" to DePuy's narrow view. 

The major flaw, as we've said in other articles about the problems with the XL Acetabular System, is the engineering. The two pieces of the implant rub together as the patient moves, releasing microscopic particles of chromium and cobalt into the bloodstream. Some patients experience pain when this happens; others have no idea of the damage being done to the bone and tissue surrounding the hip implant. Some patients and doctors have reported a loosening of the joints in the hip implant, fracturing of the surrounding bone, and full-out dislocation. 

Every hip implant releases small particles of the device's materials into the bloodstream, but the quantities are so small that the body can release them from the bloodstream as waste. In the ASR XL Acetabular System, the quantities being released are sometimes so great that the body can't get rid of them efficiently, causing metallosis.

Depuy Hip Recall Systems Glossary

 

Glossary of Medical Terms Related to the DePuy ASR Acetabular System

 Home | Personal Injury | DePuy Hip Recall | Traffic Tickets | Family Law | Criminal Defense |Get Informed

When you receive a hip implant, your doctor does his or her best to give you all the information you need to make an informed decision. However, it's unlikely that you will ever be as informed as your doctor is on any medical issue, no matter how relevant to your health. All those years of medical school amount to a wealth of knowledge that simply can't be communicated in a few hours.

That said, there are a number of medical terms to which we frequently refer in these articles, and we'd like to make sure you have them available in an easy-to-access location if you need to describe your concerns to your doctor or your legal counsel.

Acetabulum

The acetabulum is more commonly called the hip socket, and it is simply the cup-shaped impression in your pelvis where the top of your femur bone fits. The acetabulum and the head of the femur connect to form the hip joint.  

Acetabular cup

When inserting a hip implant, the acetabulum is kept intact, but is hollowed out to make room for a cup that is inserted into the hip socket to make the other half of the hip joint fit smoothly. This cup is called the acetabular cup.

Articular Surface Replacement (ASR) Hip Resurfacing System

The ASR Hip Resurfacing System is a hip resurfacing system that uses the trademarked ASR 1-piece metal bearing acetabular cup. Unlike the ASR Acetabular System, the ASR Hip Resurfacing System does not replace the head of the patient's femur. Instead, the femoral head is merely "resurfaced" with metal prosthesis that fits into the acetabular cup. It is secured to the patient's femur with a short stem inserted into the top of the femur bone.

This hip resurfacing system was recalled in August of 2010 along with the ASR XL Acetabular System, but it is a separate and unique medical device. The ASR Hip Resurfacing System was never approved for use in the United States, though it was released worldwide. The National Joint Registry of England and Waves reported a 5-year revision rate of approximately 12% for the ASR Hip Resurfacing System.

For more information on the difference between a total hip replacement and hip resurfacing, please scroll down to Total hip replacement and Hip resurfacing.

Articular Surface Replacement (ASR) XL Acetabular System

The ASR XL Acetabular System is a total hip replacement system that uses the trademarked ASR 1-piece metal bearing acetabular cup, which is placed in the hip socket. This hip implant uses a traditional femoral ball and stem (see conventional hip replacement). The "XL" in the device's name refers to the fact that the sockets are available in larger sizes.

This total hip replacement system was recalled in August of 2010 along with the ASR Hip Resurfacing System, but it is a separate and unique medical device. The ASR XL Acetabular System was sent to market in 2004 and made available worldwide. Currently, it is believed that approximately 93,000 have an ASR XL Acetabular System. The National Joint Registry of England and Wales reported a 5-year revision rate of an estimated 13% of recipients.

Criticisms of the ASR XL Acetabular System include insufficient testing, a lack of clinical testing, a high rate of failure, a delayed recall after problems were reported, poor design and engineering, and medical complications including metallosis, heavy metal poisoning, metal sensitivity, bone deterioration, tissue damage, and hip implant failure. Currently, DePuy has only recommended that recipients of the ASR XL Acetabular System who are experiencing pain or system failure have hip revision surgery.

Femoral component

In a hip implant, there are two parts to the hip joint that need replacing: the acetabular cup and the femoral component. The femoral component is the part of the implant that connects to the patient's femur bone, which runs the length of the thigh.

There are several different types of femoral components: it may be attached with cement or without, and the femoral component may replace part of the patient's femur or simply cap the top of the femur bone with a prosthetic surface and a stem inserted into the bone. 

Femoral head

The top of your femur bone forms a smooth, rounded ball that fits into your acetabulum (also called your hip socket). The part of your femur that fits into the acetabulum is called the femoral head.

In a hip implant, the term for the corresponding replacement is the same. The rounded top of the femoral component which connects to the acetabulum is also called a femoral head.

Hip implant failure

Hip implant failure occurs when a hip implant no longer performs its function properly. Often, hip implant failure requires hip revision surgery (see hip revision, below). The most common causes of hip implant failure are loosening of the hip replacement device, infection, breakage or wear, and damage to the surrounding bone. Hip implant failure may also occur due to poor design and engineering.

Heavy metal poisoning (see metal poisoning, below)

Hip replacement (total and partial)

A hip replacement is any surgical procedure in which the hip joint is replaced by a prosthetic hip implant. There are two parts to the hip joint and therefore two parts to a hip replacement: the acetabular cup and the femoral component. 

Hip replacement (total)

A total hip replacement, also called a total hip arthroplasty, replaces both the acetabulum and the femoral head with prosthetics.

Hip replacement (partial)

A partial hip replacement, commonly referred to as a hemiarthroplasty, generally only replaces the femoral head, though it may in some cases only replace the acetabular cup.

Hip resurfacing

A hip resurfacing system is a total hip replacement system that does not remove a part of the patient's femur to accommodate the femoral component. Instead, the top of the femur is simply capped with a prosthetic replacement and a stem is inserted into the bone.

Hip revision

A hip revision surgery is any surgery after the original hip replacement surgery.

Metallosis

Metallosis is a reaction to the immune system attacking metal objects within the body. In the case of a metal hip implant, the immune system reacts to the amount of metal being released into the bloodstream and concludes that the implant is a foreign body that needs to be attacked and destroyed.

As the immune system attempts to attack the foreign substance, it can over-compensate and kill healthy bone and soft tissue around the area. The surrounding area may also become infected, cutting off blood flow and leading to necrosis.

Metallosis has been linked directly to devices that release metal into the bloodstream via friction. Women, people of small stature, and the obese are more susceptible to metallosis.

Metal poisoning

Also referred to as heavy metal poisoning, metal poisoning is the build-up of metals in the soft tissues of the body. The most common heavy metals associated with poisoning are lead, mercury, arsenic, and cadmium; the heavy metals associated with the ASR XL Acetabular System are chromium and cobalt.

Metal poisoning causes nausea, vomiting, diarrhea, stomach pain, headaches, metallic taste in the mouth, and in extreme cases the loss of cognitive, motor, or language function. Chromium and cobalt have also been linked to increased cancer risk.

Metal sensitivity

Metal sensitivity can be viewed as an allergic reaction to metals. Metal sensitivity affects approximately 10-15% of the population, and as with other allergies, it can develop over time if the patient is over-exposed to certain metals. The most common reactions include hives, eczema, redness and itching; however, in patients who have received metal implants, the metal sensitivity may also cause pseudotumors (see pseudotumors).

Necrosis

Necrosis is the premature death of living cells and tissue. Usually, necrosis occurs as a result of infection, toxins, or trauma to the area. 

Pseudotumors

A pseudotumor is essentially an enlargement that resembles a mass of abnormal cells, but is in fact an inflammation. In the case of the DePuy ASR Acetabular System, doctors who have found pseudotumors in their patients have found that they are filled with fluid. 

If you have any questions about the ASR XL Acetabular System or the impending lawsuit against DePuy, please do give us a call at 800-730-7607 or contact us via our online form. We're here to help.