Hello, and welcome to Mayo Connect. We are people with a variety of conditions, who try to help one another understand what is going on.
How surprising to find out, after the fact, that there is new "hardware" in your body.

You indicate this was revision surgery, which I assume means something was wrong with the original replacement. Sometimes surgeons find bone deterioration, fractures, or other problems, and hardware - rods, plates, screws, wires - are added to stabilize everything. Perhaps this was explained to you as you came out of anesthesia, when you often don't retain info, and the surgeon never told you again?

At any rate, I would think you should go back to him for a thorough explanation and an evaluation of what is happening now. If everything is OK in the knee, you could ask for more PT evaluation - you may need to strengthen the surrounding muscles, or have an orthotic to soften the impact when walking or ???

Have you asked the doc to explain why you got new parts?
Sue