Do Stryker Hip Implants Cause Increased Metal Levels? Recalled Stryker Rejuvenate and ABGII May Cause Cobalt Metal Poisoning

An FDA warning was issued in February, 2011 which cautioned the public and physicians that metal-on-metal hip implants carried unique risks due to the potential of cobalt and chromium ion shear. Stryker Orthopedics issued an Urgent Safety Alert to all healthcare providers outlining these potential hazards in April, 2012 then issued a voluntary recall of the Rejuvenate and ABGII hip implant devices in July, 2012. One of the primary concerns centers around cobalt metal poisoning from the recalled Stryker Rejuvenate and ABGII hip systems. The symptoms of cobalt and chromium poisoning include:

·         Neurological, cardiovascular, renal and thyroid disorders

·         Disruptions in DNA

·         Bone loss, tissue destruction and death

·         Chronic or serious pain

·         Anxiety, depression, irritability

·         Loss of vision and hearing

·         Chronic headaches

·         Balance disruption, vertigo, dizziness

·         Gastrointestinal disorders

·         Memory loss

·         Skin disorders

Differences in Cobalt Toxicity between the Stryker and DePuy Hip Implants

While both the Stryker recalled hip implants and the DePuy ASR recalled implant can lead to metal toxicity, the Stryker implants are constructed differently and patients may be advised to undergo revision surgery when the levels of cobalt are much lower than those of a DePuy patient—even at levels of 2-3 parts per billion.  If a person without a metal hip implant were to go to their doctor and request a blood test to measure metal in the bloodstream the amount found in a healthy person would range from .19 to .4 parts per billion—an amount smaller than a grain of sand. An amount of 7 parts per billion or higher are definite cause for concern and, aside from the symptoms listed above, can cause constant pain in the hip region, the destruction of bone, tissue and muscle and muscle masses under the skin known as pseudotumors.

A revision will generally be recommended for a patient with a metal-on-metal hip implant who measures cobalt concentrations of 19 parts per billion. The difference between the DePuy ASR and the Stryker ABGII and Rejuvenate as far as levels of cobalt and chromium is that in a DePuy patient if the cobalt level is 20, 30, 40 or any other number, the chromium level is likely to be much the same. Stryker patients, however, are seeing a much greater disparity between the chromium and cobalt levels with the cobalt levels being much higher. The theory behind the higher cobalt levels in Stryker Rejuvenate or ABGII patients ties to the design of the Stryker models.

The “wear” in the Rejuvenate and ABGII comes from the stem and neck rather than the cup and ball portion of the joint—a surface which was not supposed to undergo wear. A Morse taper—a slightly angular junction which the physician hammers into the stem until snug and locked tightly—is implemented into the design of these two hip devices. At the location the Morse taper meets the stem, cobalt and chromium ions are released which in turn leads to cross ionization between the titanium stem and the cobalt and chromium neck. It is believed the neck portion is releasing more cobalt than chromium ions although scientists are not entirely certain why. In any case, the Morse taper has apparently created an added stress location which sends cobalt ion debris into the body of the patients.

Why the Loss of Muscle is More Serious than Loss of Bone

While the loss of bone, muscle or tissue is always a serious event, bone can be recreated using bone stock and cement. Muscles, however, cannot be artificially recreated therefore when any of the roughly 640 muscles in the body are killed through cobalt exposure, the muscle is gone forever. While the surrounding muscles can be strengthened through exercise enough to carry the loads placed on them as a result of the destroyed muscles, this extra load can also potentially lead to a burning sensation, a constant limp or gait, or, in extreme cases, the necessity of a walker or wheelchair for the remainder of the person’s life.  

FDA Approval for the Rejuvenate and ABGII

Both the Rejuvenate and ABGII gained FDA approval in 2009 through a process known as the 510k. This approval process requires minimal testing and must only meet the criteria of being substantially equivalent to a product already on the market. Stryker had no idea the Morse taper would wear in the way it has once implanted, causing cobalt ions to flood the body because there was very little in-depth research prior to marketing. Once the cobalt levels have become elevated in a patient with a Stryker recalled hip implant, it is likely the patient’s doctor will recommend revision surgery to remove the dangerous implant and replace it with a safer alternative.

Stryker Rejuvenate Hip Recall: Symptoms of ALVAL and Elevated Cobalt Levels

Hip implant recipients who received a metal-on-metal device may have a significant number of potential health issues to be concerned with. When the metal components of the implant rub against one another microscopic metal ions can be released into the body. This can be a serious matter for any patient however some patients are more sensitive to metals than others. This may explain why some hip implant patients with a relatively low amount of metals in the body can become extremely ill while others with much higher levels may have few adverse symptoms. The generally accepted “cutoff” point for the danger level of metals is seven parts per billion (The normal, healthy person will have levels between .19 and .4). This is a rather arbitrary number in that lower numbers can be just as dangerous in a recalled Stryker Rejuvenate or ABGII because of their unique design.

While any patient with symptoms of metal poisoning should definitely undergo blood tests to confirm the levels of metals although interpreting those results can be tricky. There are a number of variables which factor into deciphering the metal levels in a hip implant recipient including the patient’s age and gender, symptoms and, of course, the specific type of hip implant. The typical symptoms of metal poisoning include: gastrointestinal, renal, thyroid, cardiovascular and neurological issued, skin rashes, elevated risks of cancer, pseudo-tumors, DNA mutations, vertigo, vision and hearing loss, depression, anxiety, irritability and memory loss.

Metal Sensitivities Which Contribute to Hip Recall Symptoms

Metal sensitivities can contribute greatly to the symptoms experienced by those with metal hip implants. The Journal of Investigative Dermatology puts the number of people who experience some degree of sensitivity to nickel at approximately thirty percent. Some of those people will be severely allergic to nickel and will have violent reactions to virtually any exposure to nickel. Hip implants which are constructed of cobalt and chromium contain around one percent nickel. When the metal ions shear away from the implant, a certain number of nickel ions will also be transported throughout the body. A person with a severe nickel allergy who undergoes artificial hip implantation with a device made of cobalt and chromium could suffer extreme damage to the liver and kidneys.

Others who have metal sensitivities but not in the extreme can initially have fairly vague symptoms such as mild swelling, redness, fever, eczema and rashes with no other explanation. As time goes on and more metal ions enter the hip tissues and bloodstream, the allergic reactions will increase in severity. Chronic pain will occur as well as significant inflammation of the hip tissues. These in turn can lead to loss of mobility as well as implant failure as it pulls away from bone. Those patients who experience this level of hip recall symptoms may have little choice but to undergo painful and potentially risky revision surgery.

  

How Metal-on-Metal Hip Implants Can Lead to ALVAL

An extreme hypersensitive response to a metal-on-metal hip implant is known as ALVAL or Aseptic Lymphocyte dominated Vasculitis Associated Lesion. While doctors do not completely understand the ALVAL phenomenon it has been suggested that there may be a link between bone loss and ALVAL. When a patient has suffered chronic groin pain—particularly when that pain restricts the normal day-to-day activities—ALVAL may be suspected and tests for infection considered. Should the groin pain persist yet infection be absent, the physician may nonetheless recommend revision surgery and a new implant of a different substance.

When ALVAL is suspected the doctor will perform an exam, take a thorough patient history as well as x-rays and MRI. During a revision surgery a microbiological and histological analysis can prove the presence of ALVAL. Many doctors consider ALVAL to be under-diagnosed because of the fairly non-specific symptoms. One specific characteristic of ALVAL lies in the painful straight leg raise which is likely due to excess fluid around the joint. Among patients suspected of suffering from ALVAL, fluid withdrawn from the hip is generally a greenish gray color and a thicker viscosity. Any recipient of a metal hip implant such as the recalled Stryker Rejuvenate or ABGII who has hip recall symptoms should see their physician as soon as possible. Those with no overt symptoms should also have regular testing done to determine the levels of metals in their body.

Cobalt Hip Poisoning From Stryker Rejuvenate & ABGII Hip Implants: 510(k) Approval for the Rejuvenate and ABGII Rather than Full PMA Approval

Cobalt poisoning from hips is becoming more and more common among those recipients of a metal-on-metal hip implant device. Stryker Rejuvenate and ABGII were placed on the market in 2009, yet shortly after adverse reports began coming in regarding side effects of these two Stryker models. The Rejuvenate and ABGII both gained FDA clearance through a process known as the 510(k). To gain this type of clearance a medical device must only show it is substantially equivalent to a similar device. The problem with this type of clearance is that many times the device the new application is claiming to be similar to may have had its own share of safety issues.

There is a much more stringent type of FDA approval known as Premarket Approval or PMA. This approval requires the company to conduct clinical trials and safety testing—essentially to prove the device is safe and effective prior to marketing it to consumers. The 510(k) process requires little in the way of scientific research to prove safety. Further, at the time the Rejuvenate gained its 510(k) approval the neck was not constructed of cobalt and chromium, rather was changed later in 2009 without benefit of further FDA approval. The FDA did ask that Stryker conduct a study known as the Rejuvenate Modular Outcome Study which would follow patients for five and ten years to determine whether they had revision-free wear with no serious issues. At present this study shows it is ongoing, but not recruiting new participants.

Did the Design of the Rejuvenate and ABGII Contribute to Cobalt Hip Poisoning?

At the time the two Stryker designs were released, they were considered cutting edge as far as the innovation of the design. Offering a variety of necks and stems allowed surgeons to more closely match the implant to the patient’s individual size as well as their activity level. The titanium stem was believed to be more flexible than the much harder cobalt and chromium, adding a little “give” at the joint, while the cobalt and chromium neck were believed to be more durable. The Rejuvenate and ABGII were believed to be more stable and were advertised as being extremely long-lasting—maybe even up to twenty years. Because the two models were covered with a proprietary blend of titanium, molybdenum, zirconium and iron mixed with plasma spray, Stryker claimed there would be no corrosion from the dissimilar metals of the titanium stem and cobalt/chromium neck to worry about.

This coating failed to offer the resistance to corrosion Stryker expected, and, in fact, corrosion and fretting were occurring at significantly higher rates at the neck and stem junction. This corrosion caused microscopic metal ions to shear away from the hip implant, entering the bloodstream or the hip tissues. When the cobalt ions entered the hip region, pain as well as destruction and death of the tissue, muscle and bone could occur. Cobalt ions which entered the bloodstream caused metal toxicity among many Stryker patients. Symptoms of cobalt poisoning included: Gastrointestinal, renal, thyroid, cardiovascular and neurological damage, loss of vision and hearing, vertigo, DNA disruption, the formation of pseudo-tumors and issues such as irritability, depression and anxiety.

What did Stryker Know Prior to the Recall of the Rejuvenate and ABGII?

An “Urgent Field Safety Notice” was issued by Stryker in April prior to the recall in July of 2012. This safety notice went to doctors and hospitals—but not to recipients of the implants or consumers considering a Stryker hip implant. The notice admitted to certain flaws, claiming there was a higher-than-normal risk of fretting, corrosion and metal debris. Stryker went on to say that such things as the patient’s weight, whether the patient suffered from diabetes or had an infection, and the patient’s sensitivity to metals could all be responsible for a failed hip implant. They further stated that in some cases the neck pieces had not been adequately cleaned and that there were deficiencies in the locking and assembly of the tapers. It is unclear at this point exactly how much Stryker knew regarding the dangers of the Rejuvenate and ABGII prior to the recall. It is expected that this will be an issue in the pending Stryker Rejuvenate hip recall lawsuits as well as future lawsuits which are filed against Stryker.

Why Blood Testing is Crucial to Detect Metal Toxicity In Patients with Stryker Hip Implants

Metal hip implant recipients are likely very aware of the problems associated with the cobalt and chromium parts of the implant devices. The Stryker Rejuvenate and ABG II, both recalled in July, 2012, are not true metal-on-metal hip implants, but have found to have many of the same risks and dangers. The Rejuvenate and ABG II have a metal neck juncture as well as small metal trundles located on the neck piece. When the two models were recalled Stryker cited the risk of fretting, corrosion and early implant failure.

When the metal parts of the implant corrode, tiny metal particles can shear away from the implant, burrowing into surrounding hip tissues or entering the bloodstream. Metal toxicity can result from cobalt and chromium in the bloodstream and can have very serious consequences. Neurological, cardiovascular, gastrointestinal, renal and thyroid issues have all been found among those with high levels of cobalt and chromium as well as depression, anxiety, irritability, DNA disruption, vertigo, pseudotumor formation, vision and hearing loss and chronic headaches and pain.

There are several tests to measure the levels of cobalt and chromium in the bloodstream, including:

·         Inductively Coupled Plasma Mass Spectrometry (ICP-MS)

·         High-Performance Liquid Chromatography

·         Field-Flow Fractionation (FFF)

·         Isotope/Metal Speciation

The ICP-MS test is faster, more precise and more sensitive than the older atomic absorption tests and is able to detect metal levels as low as one part per trillion. A blood sample from the patient is ionized with inductively coupled plasma. A mass spectrometer then separates the plasma in order to record the levels of metals in the bloodstream. The high-performance liquid chromatography test may be used to test for abnormal levels of cobalt and chromium among those with metal hip implants. Chromatography consists of a mass transfer process which relies on pumps to send the sample of blood through a silica-filled column. This effectively separates the blood components from one another after which a digital microprocessor provides the blood analysis.

FFF uses fluid suspension to separate the blood sample as it is pumped through a long narrow channel. The blood may be sent through an electrical, gravitational, magnetic, centrifugal or thermal-gradient membrane in order to achieve separation. The resulting fractogram identifies the various levels of metals in the bloodstream as well as other species according to physical and chemical properties. Isotope/metal speciation can be used to measure levels of hexavalent chromium in the body. Remember that trivalent chromium is necessary for the normal function of the human body however hexavalent chromium is extremely toxic to the human body, potentially leading to cancer.

The recalled Stryker Rejuvenate and ABG II both have been found to have the potential to send cobalt and chromium into the body, causing a wide variety of adverse health symptoms. Patients who have chronic pain in the hip joint or notice any inflammation in the area should see their physician as soon as possible to undergo blood tests, MRIs and x-rays. Should the hip fail, revision surgery—both riskier and more complex than the original surgery—will be necessary.

When Stryker Rejuvenate and ABGII Hip Implant Patients Develop ALVAL and Metallosis

Patients with metal-on-metal hip implants are likely aware of the issues and recalls surrounding some models. Stryker recalled two of its all-metal hip implants, the Rejuvenate and ABGII in July, 2012. At the time of the recall Stryker declined to comment on the exact failure rate of the implants, however cited fretting, corrosion and the risk of metal debris in the body as reasons for the recall. Metal-on-metal implants were designed with longer wear in mind—the companies claimed from ten to fifteen years. Unfortunately, these claims did not pan out as adverse reports began coming in to the FDA only a short time after the Rejuvenate and ABGII were marketed in 2009.

When the metal parts of the all-metal hip implants rub against one another, there is the potential for metal debris to shear away, traveling through the body. Those metal shards can travel to the surrounding hip tissues or may find their way to the bloodstream. Some patients have been found to have a unique histological response to these all-metal implants termed ALVAL (aseptic lymphocyte dominated vasculitis associated lesion). This hypersensitivity may have a connection to bone dissolution or misalignment of the implant. Any type of misalignment can result in additional wear on specific parts of the implant and this additional wear can cause metal ion generation.

Most of those who suffer from ALVAL cannot complete a straight leg raise without experiencing extreme pain. Fluid aspirated from the hip region of those suspected of having ALVAL is generally thick and greenish-grey in color although there is no infection involved. ALVAL is not completely understood, however when a patient suffers from persistent groin pain yet infection is ruled out, ALVAL may be to blame. Many physicians believe ALVAL is under-diagnosed as the symptoms can be non-specific and systemic. Revision surgery will generally be indicated for patients with ALVAL with a different type of hip implant material.

Metallosis in a patient with an all-metal hip implant occurs when a foreign substance—in this case metal ions produced by friction of the hip implant—enter the tissues of the body. The body’s immune system sends macrophages into the body to fight the metal ions, trapping them and preventing them from spreading. The body is, however, unable to remove metal shards and the result is inflammation, pain, tissue and muscle destruction and death and bone loss. The longer these metal ions remain in the body the more likely the patient is to suffer from a variety of adverse health events.

While it appears some people have a higher tolerance for metal build-up in the body than others, in the end there really are no safe levels of cobalt and chromium in the human body. The longer the cobalt and chromium are allowed to remain in the body the higher the likelihood of a total hip failure, fracturing of the hip bone, severe levels of infection or loosening of the implant—all events which will require revision surgery.  Symptoms of metal poisoning can also occur in Stryker Rejuvenate and ABGII hip implant recipients and can include any of the following:

·         Thyroid and kidney issues

·         Gastrointestinal disorders

·         Cardiovascular and neurological issues

·         Skin disorders

·         Loss of vision and hearing

·         DNA disruption

·         Nerve damage

·         Elevated cancer risks

·         Impaired liver function

·         Reproductive system problems

·         Anxiety, irritability and depression

·         Vertigo

·         Formation of pseudo-tumors

Many of those with significantly elevated metal levels could be symptom-less until the cobalt and chromium levels are extremely high. One orthopedic surgeon, Dr. Antoni Nargol, noted that certain patients with no pain and normal x-rays were found to have “a horrendous amount of metal debris and the cups have been loosened by the metal and the metal debris gets behind the cup…and goes deep into the pelvis and has blown holes in the pelvis.” For this reason, all those with a Rejuvenate or ABGII hip implant should have regular blood testing done in order to monitor the levels of cobalt and chromium in their bloodstream.