I disagree about the crutch, cane thing. I had been walking with a horrible limp for years and this continued after my replacement. I was put back on 2 crutches until I could walk in a correct gait with no limp. Then I graduated to 1 crutch and did the same thing. That took a bit of time, but I eventually got it and moved up to a cane which I used for (I think) 2 months. I am now limp free, except when very tired and/or sore.
TKR recovery is as you describe. You think you are getting "there" and something pulls the rug out from under you.
I continue to have some issues, but have decided to push through them anyway after 3 OS's told me that nothing is wrong.
OK, so nothing is wrong and I still have pain. My PCP happens to "get it" and gives me somepercocet so I can get on with my life (though NEVER at work).
There is really no easy way out. For some of us, the road is bumpy and curvy, and occasionally we fall off a cliff. Just get back to the road and continue on trucking and even when you are ready to throw it all away, give yourself some time and then get back at it.
I am really sorry you are going through this, as this is what I went through, and to some extent, am continuing to go through. I force myself to do stuff that makes me feel 'normal'. There is really no other choice.
Best, Sandy