Please read the links the moderator gave you above and search this site for the report by Dr. Frank Noyes (cincinnati OH) for AF. If you are stiff because you have AF, you have such a small window to get it treated CORRECTLY before AF is a lifetime companion.
I am not sure who your OS is, but if he does not quote you very closely to what Dr. Noyes says, I would run the other direction. I had scar tissue carved out of my first TKR during what was supposed to be my second TKR. My first OS thought I was infected (hot, swollen, no ROM<50 degrees) so he was going to replace the first TKR.
While I was on the table, he did cultures for infection which came back negative, so he left the original TKR in, but carved out pounds of scar tissue. He did not give me aggressive PT and no followup for the scar tissue. Not only did it come back, but it came back with a vendetta and swelled my knee twice as much. I had so much swelling that both legs, my good one and bad one would swell so much I could not feel my toes.
So I went to OS #2 who swore OS #1 was a moron (for not removing the first TKR, putting in an anti-biotic spacer, treating with anti-biotics, and replacing the TKR in 6 wks) and promised me if I let him do TKR #3 he would tell me 2 wks postop what the infection was and the proper treatment for whatever it turned out to be.
My surgery was so horrendous I was calling 911 in my hospital room at 3 a.m. because i did not know where I was. The cultures came back negative (means no infection to me) but OS #2 and infectious disease doctors said I was infected, but could not tell me what the infection was.
He would not treat me any more and it looked like he let his intern close the surgery site. This was not some amateur....he is the team doctor for the Orlando Magic and worked on (Shaq's knees). He bragged several times how he had had done 4000 TKR's with only 20 infections.....well 21 if you count mine or more if you don't believe the man.
Anyway, if you have stiffness and it is scar tissue...ignoring it is the worst thing to do.
You MUST go to an AF specialist. I took Dr. Noyes report to OS#2 and he tossed it in the trash can. He told me I could let Dr. Noyes treat me or him......my bad....I made the wrong decision.
I should have hit him so hard his whole family fell down and scheduled a trip to Cincinnati before Florida 5-O shows up!!
Don't wait...don't hesitate...and don't go to anyone but an AF specialist at least until you get a solid diagnosis.