Stryker Rejuvenate and ABG II Modular-Neck Hip Stems

Stryker Hip Replacement

The Stryker Corp. is a Kalamazoo, Michigan Based medical technology company that manufactures medical devices for joint and bone replacement procedures as well as other medical technology products for the surgical profession. They hold over 5,300 patents for products ranging from hip replacement and bone prosthetic devices to blood clot removal devices and data analytic programs.  They operate in over 100 countries around the globe and has yearly sales of over $9 billion.

The Stryker Rejuvenate modular-neck stem for use in hip replacement surgery was approved by the U.S. Food and Drug Administration (FDA) in June of 2008.  The hip was designed to more closely model the biomechanics and anatomy of the human hip and to provide enhanced stability.  It was also engineered as a modular unit to make implantation easier for the physician as it was a flexible system.

The Stryker ABG-II modular-neck stem device was approved in November of 2009 and the two products were marketed for a younger patient.  They were advertised as “high performance” as they were supposed to resist metal fatigue and corrosion and would theoretically last longer.

Metal on metal hip replacement devices were known at the time of the Stryker introduction, to cause significant adverse events – some of which were debilitating.  Newer hip replacement products like those from Stryker were designed with those failures in mind and in fact companies like Stryker gained a majority of sales in the hip replacement market after companies who had manufactured all-metal products faced a mass number of injury cases.

Despite the supposedly advance design and prior knowledge about problems with other hip-replacement products, it appears that not enough investigation into their performance and safety was done.  Stryker is the subject of a number of lawsuits regarding their products and they are not the only manufacturer facing similar cases.  Stryker recalled these hip replacement products just three years after they were introduced but continues to market other hip replacement products to this day.

Design of Stryker Rejuvenate and ABG II Modular-Neck Hip Stems

The typical hip implant system is a one-piece neck and stem construction known as a monoblock.  The Stryker products, Rejuvenate and ABG-II were actually designed as a system or series of different stems and necks which could be mounted together to more closely mimic a particular patient’s anatomy and physiology.

The Rejuvenate system included 6 stems and 16 necks, while the ABG-II system had 8 right stems, 8 left stems and 10 necks for a variety of configurations.  The new modular systems were marketed towards younger patients who needed and were promised implants that offered greater range of motion and would last longer.  Stryker used a proprietary alloy blend of titanium, zirconium, molybdenum and iron and claimed that the patented formulation of the metal resisted corrosion and fretting – which is small metal flakes that break off into the body.

It was not known to the public that the devices caused injury until post-marketing data revealed evidence of both corrosion and fretting.  The Stryker implants were recalled by the Canadian health authority and the company voluntarily recalled products in the US and discontinued manufacture but many patients had already had the devices implanted and began experiencing the same problems the devices were said to prevent.

It is estimated that over 30,000 of these devices were sold worldwide, with over 20,000 sold in the US alone.

History of Stryker Hip Replacement Devices

The FDA approved the Stryker Rejuvenate modular-neck stem for use in hip replacement surgery in June of 2008.  According to the company, it was designed to simulate the anatomy and biomechanics of the human hip.  The company claimed that the hip stem provided enhanced stability and intraoperative flexibility that made implantation easier for surgeons.  The modular hip replacement was not offered for sale until the following year.

In November of 2009, the FDA approved the Stryker ABG-II modular-neck stem and the company markets the two products as a new generation of devices, “high performance” for a younger demographic.  The devices were said to be corrosion resistant and fatigue resistant in terms of construction.

In February of 2012, Stryker issued an “Urgent Field Safety Notice” to physicians, outlining the technique required for proper implantation and noting at the same time, a less than one percent failure rate due to “metallosis” which is a buildup of metal debris in soft tissues.  Metallosis is also identified as metal poisoning – caused by toxic levels of metal in the blood.  Despite the subtle warning to surgeons, there was no notification to the public at large or to patients who had been known to have received the implants.

In April of 2012, a second “Urgent Filed Safety Notice” was issued by the company to surgeons and hospitals for both replacement systems which listed “excessive metal debris and/or ion generation” caused by “fretting and/or corrosion at or about the modular neck junction,” which “may lead to increased metal ion generation in the surrounding joint space.”

In May of 2012, a report was published by Stryker stating that there were mechanical problems associated with the modular-neck stem devices.  Stryker likened the problems of potential metal toxicity to those in some patients who had received all metal hip implants which were no longer in use.  In the same month, the Canadian health authority issued a complete recall of the Stryker Rejuvenate implant.

By July of 2012, the FDA had received more than 45 severe adverse events reports of metal toxicity related to the Stryker devices, requiring revision surgery.  Stryker voluntarily recalled both the Rejuvenate and the ABG-II modular neck devices from the US device market.  They also stopped global production and all sales.

In August of 2012, Stryker finally urges physicians to notify their patients of the recalls and to encourage them to contact the company.

Serious Adverse Events and Complications the Stryker Hip Stem Implants

Many hip implant devices have been recalled since introduction and many manufacturers still face $billions in litigation costs, settlements and potential fines.  Most of these implants have focused on a metal on metal ball and socket problem which creates friction that releases metallic flakes or debris into body tissues with normal use.

The Stryker modular system with a separate neck and stem are not metal-on-metal as they do not have a metal ball in contact with a metal socket.

Despite this lack of exact replication of the problem, Stryker devices have created the same issues as they do have a metal-on-metal contact and are made of a metal alloy layering system.

The Stryker hip replacement implants can cause serious adverse events including:

  • Metallosis – corrosion and fretting which is the flaking off of microscopic or larger metal pieces, deposited into body tissues and causing metal toxicity, caused by grinding contact of metal-on-metal
  • Necrosis – tissue death in surrounding areas, likely due to metallosis toxicity
  • Osteolysis – dissolution of bone tissue from contact with metal fragments and toxicity
  • Pseudotumors – formation of “false” tumors which are large collections of solid or semi-solid mass around the implant.  It causes inflammation and may cause pain and restricted movement
  • Revision Surgery to replace implant – generally required due to severe pain and local reaction.  The hip replacement device will have to be removed and a new one implanted.  Recovery time from a revision hip replacement surgery may be considerably longer than the initial surgery due to tissue damage
  • Additional surgery for reconstruction – may be due to weakening of the bone tissue resulting in multiple fractures requiring reconstruction of the long bones (femur) or a portion of the pelvic girdle

Less serious but still bothersome adverse events caused by the Stryker hip replacement devices may include:

  • Pain in the hip, thigh or groin areas
  • Difficulty in standing or walking
  • Loss of muscle mass
  • Symptoms of inflammation in the hip, thigh or groin area
  • Dislocation of the hip
  • Other problems related to inflammation and the immune system such as rash, fatigue, headache and infection

The FDA 510(k) approval process

The FDA has an approval process for new medical devices known as the Premarket Approval (PMA).  This process requires that a new medical device undergo clinical testing in human patients according to stringent guidelines and that sufficient valid scientific evidence is presented that provides reasonable assurance that the device is safe and effective for its intended use.  The FDA also has a subsection which allows certain devices to be exempt from clinical trials.

The Stryker Hip Replacement products qualified for approval under a subsection, known as the 510(k) Premarket Notification Process.  This program allows a medical device to be offered for public marketing and use without undergoing human trials.  The manufacture is required to assert and provide documentation that the design of the new medical device is substantially similar or not different than a currently approved device.  Stryker’s new device, the Rejuvenate hip replacement product was asserted to be similar to those already on the market.  Stryker then only had to assert that the ABG-II device was similar to its already approved Rejuvenate device.  No clinical testing was required for either device prior to approval.

The 510(k) process requires only that the company conduct post-market surveillance of the product – that is, compile listings of reported adverse events that occur after implantation into a patient.  This program, the 510(k) application process is an apparently flawed system when allowed for devices that can potentially cause serious harm to patients.  Additionally, the Stryker devices were granted 510(k) status based on their modelling on devices that though approved, were already suspected of causing serious harm due to design flaws.  Many of the devices that the Stryker implants received an exception for have been recalled or discontinued due to problems of metal on metal but the Stryker design turned out to have similar problems.

Stryker Rejuvenat and ABG-II Hip Replacement Lawsuits and Settlements

Multicounty Litigation in New Jersey against Stryker Corp. is comprised of more than 500 lawsuits, including the first case filed in August of 2012.  The multicounty litigation is overseen by New Jersey Superior Court Judge Brian Martinotti.  Many more cases are expected.

The first phase of mediation for the New Jersey multicounty litigation took place in late 2013 and 2014.  Cases with eight of the ten plaintiffs chosen for the first phase were settled for an undisclosed amount.

Hundreds of additional cases have been filed in US federal courts and have been designated as multidistrict litigation which is being litigated in the United States District Court, District of Minnesota and overseen by US District Judge Donovan W. Frank.  The multidistrict litigation includes both Rejuvenate and ABG-II devices and currently includes over 600 litigants.

Judge Frank has ordered that the federal plaintiffs should coordinate with the lead counsel (lawyers) in New Jersey’s litigation cases to avoid the need to duplicate discovery process.  Any settlements in either litigation may affect the outcome of any other.

Attorneys for the plaintiffs have alleged that Stryker:

  • Was negligent in their design of the devices
  • Was negligent in failure to adequately test the devices before implanting them in human patients
  • Failed to warn the public and the medical community about the dangers associated with the devices
  • Concealed information about the risks of serious injury and the possibility of death

Previous hip replacement litigation involving other companies such as Johnson & Johnson have reached settlements that total in the $billions.  In October of 2013, Stryker completed a regulatory filing that suggests the company expects to spend between $700 million and $1.3 billion on litigation for the two products, not including insurance.  As of September 2013, $510 million had already been spent.

View Sources
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