In July 2012 two hip implant models were voluntarily recalled by Stryker Orthopedics. The two models that were recalled were the Rejuvenate and the ABG II modular-neck hip stem implants. This recall comes on the heels of around 60 different reports to the United States Food and Drug Administration (FDA) which held complaints ranging from implants corroding and slowly breaking, causing swelling and pain in the patient’s hip. The FDA had taken notice of the possible negative trend that these reports were showing since the complications the patients were reporting were not caused by underlying conditions such as arthritis.
In a press release Stryker admitted that their metal on metal bearings in their hip replacement implants could cause metallic wear particles around 20 to 80nm in diameter to be introduced into the body when the bearings were in motion. As the debris corrode, the metal ions found inside them can create an adverse reaction in the muscle tissue nearest to them causing swelling and pain.
However, the type of debris which is produced depends on the type of material the implants are made of. Each material may cause a different long-term effect on the patients body.For example, hip implants known as metal-on-metal hips in which both the femoral component and the cup are made of metal will create debris primarily made of cobalt and titanium ions, which may 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 effected.
The way that Stryker is different from the DePuy Hip Replacement line is that the hip socket joint for the Stryker models is not a metal-on-metal joint but mainly ceramic. However, they do have a metal-on-metal joint within the workings of the devices that may likely deteriorate over time. As a result, certain recipients of these implants may experience the dangerous 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. The effects of metallosis can be particularly acute in implant recipients who have a condition known as metal sensitivity. Those patients who have metal sensitivity are more likely to suffer from metal poisoning.
Hospitalization and painful corrective surgeries are sometimes necessary to alleviate pain and swelling caused by the affected Stryker implants. 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/
Hip Problems and Symptoms Information 