I don’t want to say it. No wants to say it. You signed a release but probably didn’t read it, nobody does, but TKRs can and do cause Complex Regional Pain Syndrome. You are presenting with the classic signs and symptoms of CRPS, whether Type I or II, you would not know without further testing and scans by a knowledgeable NEUROLOGIST.
How do I know. I had the same symptoms, foot pain and numbness, lack of control with twisting, folding, arching, unable to walk without arch collapsing and pain in foot and outside of lower leg (NOT PIRIFORMIS.)
It took 11 doctors, 2 years, and being told such things as I was “anxious, making it up,” “was exaggerating,” “a baby,” or the pain would “ go away,” was “all in my head,” “not that bad,” or my favorite, to “just suck it up.”

This is a RARE CONDITION AND NEEDS SPECIALIZED TREATMENT BY A PAIN SPECIALIST NOW. You may have a chance at remission. I didn’t.