I'm pretty sure that "She hurt her head" is also correct. 了 indicating the past/change and all.
Along those lines, "She injured her head" should also be fine.
Three years on, this still isn't accepted. Seriously, the Chinese course is the worst.
"Her head got injured" should also be accepted!
Have you pressed the report button? (I just did)
Because 7 months later, it still isn’t accepted.
The audio for 了 should be changed so it is the correct one, instead of the 了 as used in 了解，等
Whats wrong with "she injured her head?"
She hurt her head.