Stryker Rejuvenate Coating Defects and How They Contributed to the Recall

After gaining FDA approval in 2008, the Stryker Rejuvenate began receiving negative feedback soon after its release. Over 9,000 Rejuvenate devices were implanted into consumers who believed the implants were safe. Following an April, 2012 Urgent Field Safety Notification regarding the Rejuvenate, the device was recalled in July, 2012. At the time of the recall, Stryker cited fretting and corrosion, leading to excess metal ion debris generation as well as a higher-than-normal failure rate. Many patients implanted with the Rejuvenate began experiencing symptoms of metallosis and metal toxicity, and these injured patients were looking for answers. While Stryker has largely remained silent regarding the specific design defects of the Rejuvenate (likely due to the number of lawsuits filed against Stryker since the recall), research offers several theories.

Mismatched Components and Frictional Torque

One theory centers around mismatched components, or the pairing of a titanium stem with the much harder cobalt and chromium neck piece. Studies done over a decade ago showed that mixing alloys could result in excess corrosion, yet Stryker chose to disregard this research when designing the Rejuvenate. Frictional torque is also an issue with the Rejuvenate; while most hip implant devices show the most frictional torque at the head-neck junction, the Rejuvenate shows the most frictional torque and wear at the neck-stem taper junction. When a patient is active, that activity causes frictional torque at the cobalt-chromium/titanium taper junction, leading to the shearing away of metal ion debris.

Stryker Rejuvenate Coating Defects

Stryker claimed that the proprietary blend of alloys which coated the Rejuvenate would prevent the problem of mismatched components. This mixture of titanium, molybdenum, zirconium and iron (TMZF) was mixed with a plasma spray and the Rejuvenate stem and neck were coated. Post-market data shows the coating failed to live up to expectations. While the coating may not have increased the amount of metal shear, it certainly failed to prevent it. Further, while most metal implants release chromium and cobalt in fairly equal proportions, the Rejuvenate appears to release higher levels of cobalt.

Whether this is related to the TMZF coating is unclear, however what is becoming increasingly clear is that Stryker may have had knowledge of at least some of the risks associated with the Rejuvenate at the time of its release. Another coating used on the stem of the Rejuvenate is known as HA or hydroxyapatite porous coating and is meant to encourage bone ingrowth. On the Rejuvenate, this HA coating is very deep and rough, making it extremely difficult to remove a Rejuvenate device in the event of revision surgery. Unfortunately, while the HA coating allows the Rejuvenate to bond to bone tissue, the coating may release into the bones, putting Rejuvenate patients at risk for osteolysis, or weakening of the bone. Should the bone surrounding the implant weaken enough, total failure of the implant is likely.

 

So What Is Wrong With the Stryker Rejuvenate?

Some implant recipients and surgeons feel the FDA approval process—known as the 510(k)—under which the Rejuvenate gained approval is inherently risky. The 510(k) process allows medical devices to be marketed once the manufacturer proves the device is substantially equivalent a device already on the market. The Rejuvenate gained approval based on the Wright Profemur hip implant device even though the only similarity between the two is the titanium stem. The Profemur has had problems of its own, and it gained approval based on yet another potentially flawed device. The 510(k) process allows manufacturers to skip clinical trials and conduct few safety tests prior to selling the device to consumers. This means that unsuspecting consumers and surgeons choose a product based on the company’s claims, believing it to be safe.

Results of Stryker Rejuvenate Corrosion

Many adverse reactions can occur once corrosion of the Rejuvenate hip implant occur. Metallosis and metal toxicity are caused by tiny metal ions which shear away following corrosion of the implant. These metal ions may enter the surrounding hip tissues, leading to inflammation, infection, chronic pain, bone loss and the destruction of hip tissue. As the inflammation increases, and the metal ions continue to enter the hip tissue, it is likely that hip revision surgery will become necessary as the implant fails. While Stryker has declined to put a number on the exact failure rate of the Rejuvenate, some research indicates it could be as high as 40%. In fact, prior to the recall, Stryker claimed that adverse reactions to the Rejuvenate were “rare,” occurring in no more than 1% of Rejuvenate patients. It is clear that this is hardly the case by the number of patients who have experienced metallosis and metal poisoning after being implanted with a recalled Rejuvenate.

When the metal ions enter the bloodstream, any number of negative health issues can occur, many of them extremely serious. Once the implant is removed, some of these issues will decrease, although in some cases the damage is irreversible. Such symptoms as loss of vision and hearing, neurological and cardiovascular problems, renal and thyroid disorders, vertigo, skin disorders, gastrointestinal problems, DNA disruption, the development of pseudo-tumors, anxiety, irritability, depression and reproductive disorders can occur in those with a Rejuvenate hip implant device. While some people appear to be more sensitive to metals in the body and may develop serious symptoms even though their tested metal levels are relatively low, there are really no safe levels of cobalt and chromium in the body. Others who are less sensitive to metals may test high for cobalt and chromium but have not yet developed serious health issues. Even so, considering the high rate of failure of the Rejuvenate, many of those with no current overt symptoms may become sick in the future.

Are You a Victim of Stryker Rejuvenate Defects?

Whatever the reasons behind the failure of the Rejuvenate and its subsequent recall—many of which may never be known—consumers deserved a safe implant, and it appears Stryker failed to deliver. Following the recall, lawsuits began being filed, and will likely continue until the statute of limitations has expired. In most states that statute is two years from the time of the recall in July, 2012. Recently a Florida Circuit Court granted consolidation for thirteen cases regarding the Rejuvenate, coordinating the individual lawsuits for discovery purposes only.