I can not stress enough how important it is for people with allergies to investigate whether you have a nickel allergy before knee replacement surgery. I knew I had an allergy because I had had a reaction to eye glass frames when the "gold" outer layer wore off and the base metal, nickel, caused a rash where it touched my face. Unfortunately neither I nor my doctor thought of this in 2001 when my first knee replacement was done. Afterwards my knee was still in constant pain for several reasons, one being the fact that it was metal and contained nickel. That knee was revised (replaced) again in 2004 after I had allergy tests to confirm a nickel allergy. My orthopedic specialist (different surgeon) had only worked with metal knee replacements and did not believe that a "skin contact allergy" would occur under the skin with the replacement knee. It was revised with a metal knee containing nickel. That knee was better but still constantly painful when I put weight on it. It remains that way today. In 2009 the same orthopedic specialist that did the second surgery took one look at my other knee and said "We are going to put an Oxinium implant in that knee." I did not have to say a word. He knew in the four years that passed that his revision had not gone well and was convinced that NOT having a metal knee replacement when you have a nickel allergy IS important. He had also, in the intervening years, worked with the oxinium implant. It is great. The 2009 replacement in my other knee is doing great! Does it feel like my "real" knee? No. But my "real" knee had become extremely painful and I had to go any distance in a wheelchair. Now I walk and just wish the doctors had been 10 years more informed when they did my first knee in 2001. I have very little bone left to revise the first knee for a third time so I will live with my metal as well as my oxinium knee and can compare them every day. Oxinium wins every time!