While the Stryker Rejuvenate and ABGII are very similar in design, they do have a few very important differences, namely the length of the stem and the HA ingrowth coating used on the stem. These differences mean that the ABGII is not nearly as difficult to remove during a revision surgery as the Rejuvenate. The stem of the Rejuvenate is longer and is placed deeply within the femur during implantation. When the stem must be removed, in many cases it must literally be dug out of the bone. In addition to the extra length of the stem, the Rejuvenate implements a very rough and deep hydroxyapatite porous coating. When the bone grows into this coating, it grows in very securely, making the stem doubly hard to remove—one doctor likened it to removing a piece of rebar from cement which has fully set up. The ABGII on the other hand has an HA ingrowth coating that is much shallower and smoother than that of the Rejuvenate.
The HA coating may be one of the factors involved in the recall of the Rejuvenate and the ABGII last July, 2012. Other factors could include the design which implements an assortment of components, the TMZF coating and the mixture of metals (the titanium stem and cobalt and chromium neck). When the Rejuvenate and ABGII received FDA approval it was believed they would completely remove the dangers associated with metal-on-metal hip implants. Because the ball of these two hip implants is ceramic there would be no corrosion between the metal ball and metal neck. Unfortunately, although the variety of components allowed surgeons to choose the exact sizes for their individual patients, each place a metal juncture existed corrosion and fretting occurred. Mixing alloys has also been found to cause more problems than using the same metal for the stem and neck.
When the recall of the ABGII and the Rejuvenate occurred, Stryker stated the hip devices had a higher than normal risk of fretting and corrosion, leading to the release of metal ion debris and, potentially, complete failure of the device. Stryker’s claim that the ABGII and Rejuvenate have a 12% failure rate has been disputed by independent studies which place that number considerably higher—perhaps even as high as 45-50%. Metal ions which enter the bloodstream can cause serious medical issues for recipients. Gastrointestinal, renal, thyroid, cardiovascular and neurological disorders may occur as well as loss of vision and hearing, vertigo, disruption of DNA, reproductive disorders, the development of pseudo-tumors, irritability, depression and anxiety and chronic headaches. When the cobalt and chromium ions enter the hip tissues, severe inflammation can occur, leading to loss of bone and tissue and chronic pain.
If you are a recipient of a Stryker ABGII or Rejuvenate hip implant, it is important that you have regular medical checkups even if you have not yet experienced any problems with the implant. Blood testing to determine levels of cobalt and chromium, x-rays, MRIs and CT scans should be a regular part of your health check. Whether you have experienced problems yet or not, it is important to look into your State’s applicable statute of limitations to protect your right to recovery.