Many doctors as well as patients believed the Stryker Rejuvenate was a much safer alternative to the all-metal hip implants such as the DePuy Pinnacle or ASR. Metal-on-metal hip implants consist of a metal ball and acetabular cup. When the recipient of an all-metal implant engages in physical activities, these two metal surfaces rub against one another, causing tiny metal ions to shear away, lodging in surrounding tissues or entering the bloodstream. Because of the relatively large metal surfaces rubbing against one another, the levels of cobalt and chromium
ions can reach truly dangerous levels.
The Rejuvenate, on the other hand, implements a ceramic ball which was thought to prevent this metal ion release. When the Rejuvenate was recalled in July, 2012, Stryker stated a risk of corrosion and fretting at the neck juncture which could lead to the release of metal ions into the body. Later, it was discovered that the metal trunnions, located on either end of the neck piece of the implant could trap body fluids beneath them, also leading to corrosion. Any area which experiences corrosion experiences the release of toxic metals into the body. Because the metal surfaces which can suffer corrosion are much smaller in the Rejuvenate it would seem that it is still a safer alternative, however there is a major flaw in this belief.
Should a Pinnacle all-metal hip implant require revision surgery due to high levels of cobalt and chromium or excess pain, the surgical procedure is relatively simple and takes less than an hour. The person is opened up and the metal liner is removed and replaced with a plastic liner. While all operations have potential risks, this one is relatively safe, quick and easy. Should the ASR all-metal hip implant fail or the patient experiences high levels of metals or chronic pain, the revision surgery is more complicated than for the Pinnacle, but still relatively safe and easy: The patient is opened up and the acetabular cup is replaced. Should there be bone in growth into the cup, then the surgeon would be required to grind the cup out, making the surgical procedure both more complex as well as more painful with a longer recovery time.
However, neither of these surgeries require the surgeon to even touch the stem of the implant which is generally implanted deeply into the femoral bone during the original hip replacement surgery. Should the Rejuvenate require revision surgery, the stakes go up dramatically. Because of the location of the metal trunnions, the entire Rejuvenate implant must be removed during revision surgery. This requires the surgeon to dig the stem out of the femur—an act which can result in fracturing or shattering of the femur. Should the femur shatter the surgeon will be required to put it back together with metal bands—if it is possible to put it back together at all.
The typical Rejuvenate revision surgery
lasts from four to five hours—assuming there are no fractures of other complications. This length of time on the operating table can lead to excessive blood loss, infection and a much longer recovery time—six weeks or more. Many orthopedic surgeons will not perform a Rejuvenate revision simply because it is so difficult and so risky for the patient. So, while the Rejuvenate may not cause the high levels of cobalt and chromium in the blood, it nonetheless can cause corrosion and metal ions to enter the bloodstream. In the event a revision surgery is necessary, the dangers increase significantly.