@Kathi 777
Stop pushing for ROM and stop allowing anyone (PTs or surgeon) to set artificial dates by which you must achieve a certain ROM. Your knee can't bend until much of the swelling has gone down, because the swelling keeps it stiff.
It takes a full year for a replaced knee to heal completely and your ROM can continue to increase for all of that year, or even longer, so there's no need to rush to get ROM.
I really don't know why some therapists get so hooked up on the ROM numbers, but I wish they didn't, because it just makes you feel inadequate if you don't meet their arbitrary deadlines.
It's not exercising that gets you your ROM, it's time. Time to recover, time for swelling and pain to settle and time to heal. Your ROM is there right from the start, just waiting for all that to happen so it can show itself.
The best way to help it is to spend as much time as you can resting, icing and elevating your knee, and just doing gentle everyday activities.