For those who have asked more about the accident, this is all I know, but you can follow the story on the Chronicle of the Horse Forum on this thread.
I would also like to add that the rider in this accident was on her steady-eddy, been-there-done-that, 20-year-old, saint of a horse. She wasn’t carelessly tearing around on a green horse. It was a gorgeous day and she was just out popping over some small x/c fences when this happened. If it can happen to this pair, it can happen to anyone; hence, why we need to wear our helmets for every ride. No excuses . . . . her right collarbone that is broken, which would indicate the right side hit the ground first. She also has cervical fractures.