I've had two TKRs this year, both with the Mako robotic assistant, and both went well. My ROM is 130 degrees in both knees with 0 degrees of extension. I'm a 67 y/o male.
It sounds like you may have a buildup of scar tissue in the knee, keeping the knee tight and in pain. Now with that said, 1) I'm not a doctor and 2) you may have already looked into this.
Scar tissue would form if you didn't do all the stretching exercises immediately after surgery, or possibly if you didn't do enough. I'm not suggesting that's what happened, just sharing what I've been told.
Have you discussed this or a revision surgery with your doctor? Best of luck to you.