I am sincerely hoping that your meniscus trim goes exceptionally well tomorrow and you are out of pain in a couple of weeks. I understand your concern about the OA- I went in for a meniscus trim as well and had well established OA in my knees. I asked my OS afterward how the cartilage looked when he went in and he said it was surprisingly good for my age.
But for me the pain never left after surgery. My OS, my rheumatologist and I all believed that the surgery had caused my arthritis to flare and we treated it as such with bracing, synvisc, PT,you name it. Finally I went back to the surgeon and an x-ray showed bone-on-bone with a divot out. I had been limping over 9 months when I had my PKR.
I am sharing this story with you so that if things don't go back to normal withing the expected time frame you act and don't just assume that it will get better on its own. Have it checked out with an x-ray sooner rather than later. Had I insisted on an x-ray I think it would have showed bone-on-bone very soon after surgery. With my second knee it was great last September, started to bother in October, and bone-on-bone by Christmas.
For most people getting to bone-on-bone is a very long process, and hopefully it will be a very long time until your OA catches up with you(even better-if it never does), but if things don't seem to be going right, go with your gut and get it checked out.
Good healing and you will be in my prayers for a successful surgery.