I knew from my nickel pierced earrings I might be allergic to nickel and after doing allergy testing it was confirmed that I was. My TKR surgeon is known for taking a mold of your knee before surgery and he uses that for the hardware unfortunately the company only uses nickel so I was not a candidate for this process and had to use an off the shelf titanium hardware. I am one of the unlucky ones that TKR recovery has been difficult and often wonder if they would of been able to make a mold of my knee first my recovery would be better .