I am 77 but quite fit and healthy. Until recently I used to do hill walking quite a lot. Just before christmas 2014 I woke up with pains in my right knee. Although the pain arrived suddenly it has not gone away, It is worst first thing in the morning when I am reduced to limping. The pain usually lessens during the day but is bad again when I lie in bed. My doctor thinks it is osteoarthritis but can such a condition set in so markedly overnight? David Dugdale YYYY@YYYY