I am similar to silverling48, having been advised I would need an operation but have tried to be proactive with exercise, yoga, pilates, swimming & walking over several years to try and keep the operation as far away as possible. I did not know of the grading system so will find out more. We are of course all different with regard to pain levels and I wonder what others consider to be the upper limits as it were before deciding to go for the op. My other knee is also hurting now, so going up stairs or down hurts both knees, one more than the other, walking or standing just a dull ache most of the time, exercise I go as far as I feel able, night time is often quite bad with the aches & pains so not very restful. I suppose really what I am asking is when do you say to yourself enough is enough?