I've been fortunate and had two successful knee replacements in 2022. I was 67 y/o when I had the TKRs.

I talked to my Dr about how the prostheses are sized. I don't recall what he said about the femoral replacements, but for the tibia, the edges of the plateau, the flat part of the prosthesis, should be inside the edges of your tibia.

That said, I doubt that a Dr would make such a mistake, but I suppose anything can happen. And you said you have small bones, so it may be worthwhile to have a second Dr look at your X-rays.

I don't think the prostheses are custom made. The size that is available that is best for you is used, and there are several available on the day of surgery. But what if your bones are so small that none of these would fit?

Again, I think it's unlikely, but you have nothing to lose by checking.

Another possible cause is inflammation. I have osteoarthritis and have only recently cut out all (ok almost all) refined sugar from my diet. Sugar is a significant cause of inflammation, and inflammation causes joint pain.

I hope something here helps. All the best to you! Joe