I managed to wake up around 4 am with my knee throbbing away and a brief walk to and from the bathroom seemed to fix it and then at 6:30 it woke me up and I decided to get up, stick a knee brace on and come downstairs. Actually 06:30 isn't so bad in reality just an hour before my 'usual' so it's not lying awake for hours or bad thoughts but my knee has been bad for years but not in any meaningful way. The last time it was bad was July a couple of months ago and it hasn't bothered me since.
No doubt another benefit of getting old although the damage was done around 1994/5 if I remember properly. Cricket that I shouldn't have been involved in and got press-ganged into. It didn't feel bad at the time but I ended up having around 6 weeks where I was driven to and from work in Canary Wharf, London. Hobbled into the building, up to 11th floor and then worked there all day and then hobbled back out to my waiting car for the journey home.
It's OK at the moment, I've put some freezing stuff on and a brace over so let's hope that sorts it out.