Good news: I really, REALLY have been working on regaining my knee's range of motion. And I have so much of my range back, I'm really astounded. And glad... one of my fears is that if I lose my balance, I don't want the knee to get damaged if it's abruptly and accidentally pushed past its self-imposed limit. That could turn into a really nasty setback, so it's a problem I'd rather avoid.
HOWEVER... in physics, we learned that for every action, there is an equal and opposite reaction. In this case, the reaction is a whole lot of OUCH. Every time I reach that range-of-motion limit, there's an "ouch" involved. Every time I let the knee sit there and stay flexed at that angle for a while, "Ouch." And every time I try to go a little bit beyond that limit, "OUCH."
But it's working. Slowly but surely, that range is coming back and it lets me flex it just a little bit farther the next time I try to test the limit.
The knee also sends off some strings of "ouch" signals in between these flex sessions. But that's why God created ice and pain meds. ;)