The Problems with Stryker Metal-on-Metal Hip Replacement System

Orthopedic disease and trauma affect millions of people each year, media reports say. They potentially limit mobility, decrease productivity and reduce the quality of life. There are patients around the world who have come to depend on hip replacement products in hope that it may help them by restoring normal function, reducing pain and returning their normal daily activities. Stryker Orthopaedics is a global leader in the development, manufacture and sale of orthopaedic products and services such as the hip replacement systems. However, their orthopaedic products are associated with problems which led to recall. The implant systems Rejuvenate and the ABG II are voluntarily recalled by Stryker.

Stryker’s decision to voluntarily remove Rejuvenate and ABG II modular-neck stems and terminate its global distribution of these products comes after continued post-market surveillance. Because these two hip replacements are made of metals, it could potentially generate metal debris as the joints wear. It has been thought that metal debris is incompatible with the human tissues.

Metallosis, also known as metal poisoning, occurs when metallic debris is released into the body’s bloodstream. Usually, the condition refers to cobalt and chromium particles that are absorbed into tissue as a result of faulty metal hip implants. High levels of metal particles may potentially cause organ damage. Small metal debris is produced by the grinding of the two metal surfaces (ball and socket). As a result, the immune system identifies the metal ions as foreign objects and aggressively attacks the soft tissues containing them. Damaged and inflamed tissue can contribute to premature loosening of the hip implant. Metallosis may also lead to necrosis which is characterized by extreme skin rash and death of skin cells.

The Food and Drug Administration (FDA) has received over 16,800 reports of problems with metal-on-metal hip replacement systems from 2000 to 2010. Fourteen thousand patients had to undergo revision surgery to remove the defective implant and replace it with a new one. However, government health experts said that there are a few reasons to continue using the metal hip replacements, amid the growing evidences that the device may prematurely break down and expose patients to dangerous metallic particles.

People who received the Rejuvenate and ABG II implants may potentially suffer severe injuries. For this reason, they may need to consult a doctor or simply refer to the Stryker Hip Recall to know the potential complications.

References:

drugwatch.com/hip-replacement/

nytimes.com/2011/08/23/business/complaints-soar-on-hip-implants-as-dangers-are-studied.html?pagewanted=all&_moc.semityn

rsc.org/chemistryworld/2012/07/why-some-metal-hip-replacements-fail

usatoday.com/news/health/story/2012-06-25/metal-hip-implant-risks/55845858/1

Metallosis, a Serious Side Effect of a Stryker Hip Replacement

In July 2012 two hip implant models were voluntarily recalled by Stryker Orthopedics. The Rejuvenate and the ABG II modular-neck hip stem implants were the two hip implant models which were recalled.The recall followed over 60 reports to the United States Food and Drug Administration (FDA) that the hip implants corroded and fretted, resulting in pain and swelling in the hip region. The FDA noted that these reports indicated a possible negative trend with the Stryker hip implants due solely to problems with the implants and not to associated problems resulting from arthritis or other medical conditions.

Stryker issued a press release that admitted that metal on metal bearings in the hip replacement implants could create metallic wear debris between 20 and 80nm in diameter when the bearings were in motion.   The corroding debris caused by the metallic bearing eroding may create an adverse reaction in the local tissues and create swelling and pain.

The material in which the implant is made of is important since the composition of the hip implant will determine what kind of debris it gives off. Each material may cause a different long-term effect on the patient's body. One example is if the hip implant is a metal-on-metal hip implant, meaning both the femoral component and the cup are made of metal will create debris primarily made of cobalt and titanium ions, which can cause a condition known as metallosis.  Metallosis is a rare disease in which metallic debris are introduced into the body and cause pain in the soft tissue, in the case of hip replacement the tissue around the hip area is most affected.

Stryker’s hip replacements are different from more common hip replacements such as the DePuy series of hip replacements because the hip socket joint for the Stryker models is not metal-on-metal joint. Most of their products are ceramic. They do, however, have a metal-on-metal joint within the workings of the recalled devices which can deteriorate over time.   Because of these metal-on-metal workings inside the Stryker hip replacement, many patients have begun to suffer from the effects of metallosis. One such side effect is that these metal debris can cause grey discoloration of the tissue surrounding the implant, this usually means that the tissue is oxygen-starved and dying.   For those who have an illness called metal sensitivity having metallosis is particularly dangerous. Those patients who have metal sensitivity are more likely to suffer from metal poisoning.

In some cases the damage has been done and the only way to fix things is through hospital and corrective surgery. Stryker has begun warning patients on its website that if they began to experience  pain or discomfort in their hip area they may visit their doctor as soon as possible.

References:

aboutstryker.com/hip/disclaimer/