I've been following this conversation and think there is something else at play here.
Not denying there is an injury, but if you consider and accept that young people are not always going to follow instructions, and that girls/kids of any age going down these slides will 'cat slide' in an attempt to slow their speed at least several times a week at least (amongst the thousands of kids using these slides), then one would expect these injuries to occur more often given each person has more or less the exact same ride conditions.
Logically thinking, it either happens more often and just isn't reported, or this young girl had an underlying issue.
Either way the truth will come out and I think it is important for the public to know the outcome as many of us have kids and these types of issues relate to their safety and the ability of parents to make informed choices on risk of these rides.