altabello

I'll be traveling TATL + connection in Europe in May. I tore some ligaments in my knee in January, but the knee is on the mend. I do have a knee brace that I use for hikes, longer walks, or walking on uneven terrain. In order to protect the knee, it's a tight fit and has to be worn under my pants. I could walk through security without it, but would have to put it on, if there's a significant walk through the airport to the gate. Since I have to go to a restroom or other private room in order to put it on/take it off, I'm wondering if it would be easier to just wear it through security? What issues should I expect? If I'm not wearing it, it wouldn't count as a carry-on item, correct? It's a hard plastic, hinged brace, so it wouldn't fit in a carry on bag, unless it's in its own bag.
My knee swells if I'm stuck in a seated position for over an hour. Ice & elevating helps, but a ziplock bag with ice is hard to balance on top of your knee. Can I bring my wrap-around, velcro ice packs (filled with the blue gel beads) on the plane? Does anyone have any ideas on other icing options that stay in place and could be replenished easily?
Should I obtain any doctor's notes that could help in dealing with TSA, FAs, etc.?
Thanks for all suggestions and helpful information!