December 30, 2014 - ATTENTION ALL STRYKER HIP IMPLANT RECIPIENTS - If you were implanted with a Stryker Rejuvenate or Stryker ABGII Metal Hip Implant, you should know that Stryker Corporation has recently reached a settlement agreement in its Multidistrict Litigation over these two hip models. Read more about this recent Stryker Hip Settlement here: Stryker Hip Settlement Agreement Explained
History of the Stryker Rejuvenate and ABGII
The Rejuvenate Modular Primary Hip System gained FDA approval on June 3, 2008, however marketing for the hip implant device did not begin until February, 2010. The ABGII gained FDA approval in 2009, and was marketed with the Rejuvenate in 2010. Stryker publicized their two newest hip devices aggressively, claiming there would not be the same problems with metallosis and metal toxicity such as those experienced by other metal-on-metal hip devices. Stryker also claimed that, once implanted, the ABGII and Rejuvenate implants would last from 15-20 years. Unfortunately, these claims did not work out as expected, and within mere months of implantation, some patients began experiencing serious, adverse side effects.
The Stryker Design
The Stryker design for the Rejuvenate and ABGII was considered exceptionally innovative at the time of its release. Unlike most other all-metal hip devices, the Stryker ABGII and Rejuvenate utilized a ceramic ball, rather than a metal ball. A variety of neck and stem components allowed surgeons to construct a hip implant device which was could be custom-fit to the individual patient, according to the patient’s size, body type and levels of activity. It was also believed that the Stryker design would add anatomical stability, due in part to the titanium femoral stem which more closely followed the natural contours of the femur bone. By conforming to the femur, the designers of the implant believed there would be a more even load transfer pattern which would closely proximate the natural stress distribution in the human body. The ABGII implant offered eight left and right stems, and ten modular necks in varying lengths and angles, while the Rejuvenate offered half a dozen stems and sixteen modular necks.
Stryker’ assessment of their new design, according to the Master Long Form Complaint and Jury Demand for ABGII Modular Hip Stem Cases, is that, “Unlike most prosthetic hip implants, the ABGII Modular Hip Stem is an artificial hip replacement device consisting of two basic components: a gas-atomized dispersion strengthened chrome cobalt (GADS CoCr) neck that is inserted into a titanium stem. The neck rests inside of the stem, which is implanted in the patient’s femur. The stem has a PureFix hydroxyapatite coating. Scales are incorporated into the stem’s anterior, posterior and medial surfaces to encourage the transmission of vertical loading from the implant to the bone and reduce the dependence on friction at the hydroxyapatite surface. The ABG II Modular Hip Stem can be used interchangeably with any number of Stryker bearing surface components (which comprise the ball and an acetabular cup or socket). The bearing surface system or components are unrelated to the ABG II Modular Hip Stem’s method of failure.”15
This description fails to address many of the problems associated with the recalled Stryker Rejuvenate and ABGII and does not mention that the Stryker neck design fits into the stem through a Morse taper junction which may create mechanical stress during periods of body motion. In any case, a design which was supposed to offer patients longevity and safety, by all accounts, failed dismally to deliver on those promises.
Safety Warnings Regarding the Stryker Rejuvenate and ABGII
In April, 2012, Stryker issued an Urgent Field Safety Notification to hospitals and surgeons, acknowledging potential dangers of the ABGII and the Rejuvenate. Stryker stated that the intent of the letter was to list all known potential hazards associated with the two hip devices. The letter further stated that the instructions for the two hip systems had been updated based on a “reported rate of less than one percent for revisions potentially associated with fretting and/or corrosion at or about the modular neck junction.”16 The reality of the actual revision rate numbers would turn out to be vastly different from this initial claim.
Stryker listed the potential hazards of the Rejuvenate and ABGII hip devices as “excessive metal debris and/or ion generation. Fretting and/or corrosion at or about the modular neck junction may lead to increased metal ion generation in the surrounding joint space.”16 Stryker noted that patients with a heightened metal sensitivity could experience more extreme allergic reactions, leading to revision surgery. The notification further stated that excessive fretting debris in the joint space could lead to osteolysis. In the Product Correction Bulletin which accompanied the Urgent Field Safety Notification, Stryker stated factors which could potentially increase the risk of adverse effects, including:
· Additional femoral offset which could be caused by excessive patient weight
· Patient’s prior history of diseases such as diabetes or infection which “may play a role in potential corrosion of an implant as these conditions may affect the pH of the tissue surrounding the implant.”16
· Inadequate locking or assembly of the Morse tapers
· Inadequate cleaning of the neck taper “may lead to increased debris generation.”16