Hi, Annie:
In my own case, when I have knee involvement that the doctors actually called 'water-on-the-knee,' it is due to colitis similar to septic hip. The lymph accumulates in my knees and then gravity sometimes takes it down to my ankles. I had pain when walking for over a year after my worst bout with this before it finally relented/repaired--but I had to treat the colitis first.
Health,
John
