I had mine removed because one had become displaced and was causing pain and bruising. I went back to work the next day, teaching 1st graders. I took a Vicodin around lunch time, but other than that, was fine.
I originally had been told that I would have local anesthesia because the surgeon was only planning on removing the one wire, but after an x-ray, he saw that two others were also out of whack so I had general anesthesia and he removed them all through a 1 inch incision. The way I understand it, they cut the wire and then it slides right out because the bone doesn't adhere to the metal. I had one wire that the bone had grown over in a weird way, and he left a small piece in my sternum. Because of his desire to leave me with a very small incision (my previous was horizontal and he didn't want to reopen it), and the stretching of the skin required to reach all the wires, I had LOTS of bruising. My entire chest was BLACK for a few weeks, eventually turning into a beautiful green donut!
Good luck! It's a very minor surgery, especially in relation to the other one you had!