Don't worry about your ROM. It's going to improve as your swelling goes down.
I'm not surprised it had decreased after the session with the different PT.
Next time your therapist isn't available, just give PT a miss. You won't lose anything and it won't set you back.
In reality, going to PT and doing lots of exercises is not necessary.
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.
Any exercises that need a second person to help with them should be avoided.
It's all too easy to get trapped into thinking that the harder you work, the better the result will be, but that just isn't true for recovery from a knee replacement.
BoneSmart philosophy for sensible post op therapy
TKR: work “smarter” and not “harder”
Knee recovery - Lose the Work Ethic!!
Remember that, in spite of what your PTs and surgeon seem to be telling you, there is no need to rush to get ROM. There's no deadline you have to meet, because ROM can continue to improve for a year, or even longer, after a TKR.
Myth busting: the "window of opportunity" in TKR
How mean and petty of your stand-in PT and your surgeon to threaten and lecture you as if you were a child! You're not! You're a responsible adult.
This is your knee and you are in charge of it. You're the only one who has the right to say what will happen to it. Others can advise, but you can choose whether or not to accept the advice.
Saying no to therapy - am I allowed to?
I know all this must be very confusing, but your knee knows what it's doing. Listen to its messages and try to do all you can to keep it happy.
My surgeon doesn't allow any PT at all for the first month after a knee replacement. He says your knee needs that time, to start on its journey of healing. For that month, we rest, ice and elevate our leg, and walk around the house.
After that month, we just go to PT once every 2 weeks, where we are shown a few new exercises to do at home.
His patients all do well and achieve good ROM, as I did, and he hasn't had to do a manipulation to help with ROM for the past 4 years. I think that speaks for itself.
I didn't go to PT at all after my last TKR and my knee is great! It's strong and reliable. It straightens fully and bends to somewhere between 125 and 130 degrees - all without doing any formal exercises, but just letting the activities of daily living be my therapy.