To ME (who is very much NOT a dermatologist), it looks like a hypertrophic scar - I have one on my shoulder from one of the scope ports during my slap repair. Mine has never flattened. I'm thinking silicone strips (which are hard to keep on a knee while moving) or a silicone gel (scar away or kelo-cote) might be a relatively benign thing to try.
The upper part of my scar keeps wanting to 'pop out', but every time I put my kelo-cote on it, it goes back down into place. I think there are things dermatologists can do to help, too.
Your green has inspired me to think about planting some seeds to sprout for March/April (we will likely have one more freeze before spring fully sets in)... Would you believe we actually had a FLY in our house yesterday? I looked at Bill and said "did we leave something electrical on?" He laughed his bootie off, and said "um, Liz.... It's a fly - you know, those annoying things that we see in the spring and summer?" I told him I was going to 'fly' over and use the 'swatter' on him if he wasn't careful!