I've heard of people warming up their knee before doing any physical therapy - that is, after the initial recovery period of, say, 6 weeks. Ice is the thing to turn to for swelling. It doesn't hurt to experiment, see what works for you.
When my knee was limited by adhesions after my original TKR, it was quite swollen. I've now had a revision and already going from moderate to mild swelling, which never happened with the original TKR.