The Stryker Rejuvenate and ABGII were recalled in July, 2012, after a significant number of implant recipients developed serious medical problems from the hip device. Stryker changed the design of these two models substantially; rather than using a cobalt and chromium ball, they used a ceramic ball and instead of a single modularity device the company designed a dual modularity device which offered surgeons many more options when placing the implant. With a variety of component sizes, surgeons were able to custom fit each hip implant device to the patient’s body size and type as well as to their level of activity. The Stryker Rejuvenate and ABGII were specifically marketed toward the younger, more active patients, and prospective recipients who had heard about the release of metal ions into the hip tissue and bloodstream when a metal ball was used felt like they were choosing a much safer alternative.
Why Dissimilar Metals Cause Excess Corrosion
When Stryker recalled the Rejuvenate and ABGII, they cited a higher-than-normal risk of fretting and corrosion which generates metal ion debris and can lead to metal toxicity and failure of the hip implant. More recently it has been found that a serious mismatch between the titanium stem portion and the cobalt and chromium neck which may be responsible for the high levels of metal ion release. The titanium stem is coated with a blend of titanium, molybdenum, zirconium and iron mixed with a plasma spray.
Studies done over a decade ago found corrosion to be significantly higher in hip implants which used dissimilar metals versus those components which are constructed of the same metal. In fact, 42% of mixed metal hip implants showed moderate to severe corrosion while only 28% of those constructed from one metal showed the same levels of moderate to severe corrosion. A more recent study showed a galvanic reaction occurred when a titanium stem and a chromium and cobalt adapter sleeve were mixed, likely because cobalt and chromium are much harder metals.
Additional Reasons for the Failure of the Rejuvenate and ABGII
Stryker’s Rejuvenate and ABGII may also be subject to undue frictional torque. Where the modular neck and stem meet, frictional torque leads to more wear on the joint. This happens to be a joint that is not supposed to suffer undue wear, therefore this is one more reason the recalled Rejuvenate and ABGI have caused problems in recipients. Excessive wear on a joint can be responsible for the formation of pseudo-tumors as well as total failure of the hip implant. The excess wear on the joint junctures as well as the dissimilar metals can cause metal ions to build up in the bloodstream and hip tissues causing loss of hearing and vision, vertigo, depression, anxiety and irritability, skin disorders, DNA disruption, cardiovascular, neurological, gastrointestinal, renal and thyroid disorders, some forms of cancer, reproductive issues and loss of memory.
Further, when the hip implant fails and revision surgery is required, the Rejuvenate holds the distinction of requiring the lengthiest, riskiest and most difficult revision surgery. The stem must be pried loose from the femur which comes with the possibility of femur fracturing or shattering. The patient is required to undergo a lengthy recovery period, meaning they are losing their regular paycheck in addition to having to pay extensive medical expenses.