Then... the blue block extension exercise.
I've never heard of the blue block extension exercise. Please will you explain?
The pain rehab doc comes in and tells me that if I do not do the exercises today that the knee will be stiff and unusable. They do this all the time and this is how you get a useable knee. He said that he did not mean to sound unsympathetic but... the blue block is brutal but has to be done.
What he said was a load of rubbish. Try not to take any notice of it.
In spite of what you were told, there's no need to rush to get ROM (Range of Motion) because it can continue to improve for a year, or even much longer, after a knee replacement. There isn't any deadline you have to meet:
Myth busting: the "window of opportunity" in TKR
In any case, 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.
This is your knee and you are the only person with the right to say what will happen to it. Your surgeon has done your operation, but he/she doesn't own your knee. He/she can recommend what you do, but you have the right to choose whether or not to accept that advice.
Saying no to therapy - am I allowed to?
Since the blue block exercise causes you so much pain, don't do it.
Your knee is wounded and it needs gentle treatment, so it can start to heal. Remember the advice given to you in Post #7 -
a. If it hurts, don't do it and don't allow anyone - especially a physical therapist - to do it to you
b. If your leg swells more or gets stiffer in the 24 hours after doing it, don't do it again.
Myth busting: no pain, no gain