I can add my DD to this thread now. Yesterday at gym (the social, home-school rec class she goes to once a week, as opposed to her actual training group), she rolled her ankle on the trampoline. She cried a little bit, but not much (she's 5). Then she ran out of gym, climbed up the outside of the stairs the way she always does, and went grocery shopping with me for an hour. Got home, and I noticed her hopping over to the lounge. Take her shoe off to discover her ankle twice it's normal size. X-rays today show a possible fracture and she also has torn ligaments.
Of course, today, any time anyone so much as looked at her, she was shaking and tears pouring down her face. But bust her ankle and run up the stairs at gym? No worries.