Hello Brenda. I was mentioned by Amanda and will share my experience.
TKR left knee April 2021 that I consider highly successful. 9 months out: occasional minor soreness, mostly after exercise + some continued tightness that I attribute mostly to continued healing. A year is not an under estimate.
Flexibility 110 +. I really haven’t bothered measuring lately but whatever the “number” good enough for me.
I had flexibility problems until post-op swelling finally reduced at about 6 weeks. A course of prednisone helped a lot.
I found icing several times a day and elevation- particularly after exercise - critical for first 3 months to control pain and swelling.
I am not a PT but exercise followed by being non-functional due to pain and stiffness? Could be doing too much too soon?
Hope you are able to figure out what works best for you.