Dr. Su’s Protocol for Metal Ion Testing Metal Ion Testing The testing of metal ion levels after hip resurfacing is controversial, to say the least. Because we are still learning about the metals used in resurfacing, how they are released (and in what quantity), and how the body reacts to these metals, there are no definitive guidelines for metal ion levels in every patient. There has been research done regarding the amount of metal ions that we expect to be produced and remain in the body after hip resurfacing. However, what we don’t know is: “At what level do these metals pose a problem?” It seems that different patients will have different tolerances for the amount of metal in their body – some react to the metals at a very low concentration, while others have no symptoms, even if their metal ion levels are high. This is what makes it difficult, if not impossible, to produce guidelines for metal ion testing. Many surgeons believe that metal ion testing will only lead to more questions and concerns, since we don’t know exactly what to do with this information. There is no cutoff value for metal ion levels; that is, there is no level that would make a revision necessary, at this point. The British Orthopaedic Association has made recommendations that cobalt and chromium levels be below 7 parts per billion, per hip; however, there can be patients who have levels above this threshold who do not have problems. The United States FDA has not made specific recommendations regarding metal ion testing; in their Safety Communication dated January 17, 2013, they state: “The FDA does not believe there is a clear need to routinely check metal ion levels in the blood if the orthopaedic surgeon feels the hip is functioning properly and the patient is asymptomatic.; and “At this time, the FDA is not recommending a specific metal ion level as a trigger for revision or other medical intervention.” I believe that metal ion testing gives information about what is happening in the joint with regard to wear. With conventional metal-on-polyethylene bearings, we can measure wear on an x-ray; with metal-on-metal, this is not possible, since the ball and socket are the same material. Therefore, I find the use of metal ion testing to be informative as to what is occurring inside the joint. Perhaps if I identify metal ion levels elevated above a level that I Believe to be normal, I can help guide a patient into modifying his/her activity to reduce the amount of wear. In addition, I believe it provides a check to make sure that a patient’s kidneys are functioning properly to filter the body of excess metals. My current protocol is to test the metal levels yearly, in all patients. Once I have gathered enough information that a joint is functioning well, then Decrease the frequency to every 2 years.