HI Sherry,
I had MUA 3 months after LTKR. I was having issues with extension mostly, not so much with flexion. I had -15 for extension and about 105 for flexion. During MUA, OS got me to -5 and 118. He said he heard a loud pop during the procedure and said I would never have broken through the scar tissue on my own. I felt great and could feel the better extension after just a couple of days. Thats when PT started with aggressive pushing, which caused swelling, which inhibited ROM and I lost what I had gained through the MUA. Also, just because your knees look similar in size, doesn't mean the soft tissues inside the knee aren't swollen. Think about the compact nature of the joint and how just a small inflammation might cause tightness.
I encourage you to use the MUA as an opportunity to jump start your recovery. Just remember that it will be swollen and it will be sore. Ice and elevate, take it easy. You will be amazed at the better outcome. As others have said, you are not ever going to train your knee into submission, it is healing and it simply takes time. I know that patience can be hard to come by all too well. I feel your pain and can relate to any frustration you feel. I am almost one year post TKR, going in on the 14th for a revision because I am still missing extension at -15-20. I wish I had done many things differently from the beginning of this journey. Starting Tuesday, I will be doing things differently.
Good luck tomorrow and keep us posted. If you read through my thread, I have detailed notes of how I felt right after the MUA. It may help provide a little bit of insight.
Looking forward to your updates!
Be well,
Dawn