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Metal Ions

One concern with metal on metal has been that all metals release ions. Ions are the basic element of the metal. In metal such as chrome cobalt, the ions of chrome and cobalt are gradually released from these metals. These ions are normal in our bodies and, in fact, are necessary for life. Drinking water, for instance, from the city supply contains fairly high levels of metal ions. There are no known ill effects of metallic ions. Metal on metal has been used for over 50 years in total joints, and there have been no reported association with cancer development or any other problems. Patients often ask Dr. Clyburn what he would do if he needed a total hip arthroplasty. He would without hesitation have a metal on metal implant with a large femoral head.

There are two groups of patients where Dr. Clyburn is hesitant to use a metal on metal arthroplasty:

1. Young women. Young women who may become pregnant should understand that although there is no known ill effect of increased metal ions on the developing fetus, we cannot say without reservation that there could not be a problem. There is one study which reported that metal ions do not cross the placenta. This study was very small and has had its validity challenged. Basically, it is simply not known. Dr. Clyburn has used ceramic on ceramic in most young women.
2. Renal failure patients. Dr. Clyburn has used metal on metal with great success in patients who have had kidney transplantation. With well functioning kidney transplants, the chance of a patient having to go onto dialysis is low. However, because the metal ions are naturally eradicated from the body by the kidneys, patients on dialysis may have levels of metal ions which are far greater than in an otherwise normal person. Therefore, Dr. Clyburn usually does not recommend metal on metal in patients who are on dialysis.