Hi, Coniglietta, and welcome to BoneSmart! I'm glad you decided to join in the forum. Please do contintue reading here both in the BoneSmart Library and in the pre- and post-op forums. The more information you have, the less nervous you'll be about it all.
Also, be sure and post any specific question, concerns or fears you have....we'll address them and hopefully that will make you more relaxed. The surgery is a big step, but it's one that gives you an excellent chance for a normal, painfree life again.
As for your question about thinking about having "metal" in your knee....hon, you'll not feel it as anything but your knee. Your old joints are worn out and unable to carry on for you. Much as you might get a crown on a bad tooth, you're going to get some new parts for your bones that will enable the joint to work properly.