It's difficult to know what to suggest as it looks to me like your poor knee has been abused by PTs and by a rather unfriendly doctor right from the outset.
I have been faithful about riding the exercise bike 15 minutes a day, 3x/day
With a swollen, stiff knee you don't need to do training, you need to do stretching. Sitting on the bike, turning the pedals with no resistance, for about 20secs is all you need. Do this lots of times a day. When you can turn the pedal easily, lower the saddle a tiny bit.
At no time should you put any force through the knee. No knee bends or anything like that.
Another good flexion regime is to use a rocking chair, just gently tip backwards and forward to the point of resistance in the knee.
There are a couple of other stretches outlined from my exercises thread, see my sig below. The skateboard one is good.
Your husband could help with an extension stretch
- You sit on the floor, TKR leg out straight.
- Rest the heel on a fairly thick book or similar, to get it may 2" off the ground (with 8 degrees of extension you may not need this)
- partner kneels at right angles to your leg, placing one hand about 6-9" below the knee, one about 6-9" above.
- gently pushes the leg towards the floor until you feel a good stretch through the back of the leg BUT NO FURTHER OR IT WILL HURT
- holds for about 20sec
- eases off, waits 30sec, repeats.
- repeat 3 or 4 times.