Wednesday, September 19, 2012

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/

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