Well, if you lucky enough to find a good PT place, especially if they have walking swimming pool, you may benefit from it greatly.
Try to find a place locally where you can go and swim at least couple times a week, this helps a lot with Arthritic pain/changes.
OA is age related changes in our bodies and may affect any part of it. MRI will show every little thing in your knee, and if this prevents you from being active, they may offer some knee shots. For some people it works for some is not, depends on damages, age, etc. I had good once, forgot the name, but it made out of chicken. Suppose to be very expensive and helpful, many people say it great help to them.
They may offer epidurals; watch out for them especially now and read tons of information since latest fungal meningitis affected those who had latest epidurals done. I had a month ago few done, I am OK but my DR didn't use the troubled ones.
Try your best to stay active; swimming is the best thing for this type problems. PT, walking... Your body will tell you what you are capable of and what is too much for you. You should listen.
OA is something we all have to deal with sooner or later. So try your best!