Does this need medical attention?

[HoollyWugger]

DS (13) fell off his scooter (probably a good speed, mid-trick) and landed mostly on his left knee.

He's icing it now, but is that enough? He's likely to ham it up (autism-related issues) so I won't be able to accurately tell how bad it is in terms of pain while weight-bearing etc ...

Sounds like you’re doing the right thing. I’d leave it and see how he is in the morning

That's my gut instinct but I do tend to err on the side of healthy neglect

It's obviously grazed and a bit swollen but as long as he can weight bear it should be fine. Will he take ibuprofen? That'll help with the pain and swelling. Icing it is a good plan, and get him to rest and keep his leg raised if he'll do that.