Participles - Past simple + Simple continuous or past simple + past simple?
Solution 1:
I can see why this is confusing. The relevant distinction between the participles is whether they are active or passive, and you think that since Megan has been hurt (passive), the passive participle hurt is more appropriate here.
The problem is the object "her leg". A passive particple cannot take an object.
You could say "Megan fell of her bike, hurt", but there is no way to attach "her leg" to that. "Megan fell off her bike, hurt in the leg" is grammatical, but I don't find it very natural.
It might seem odd to use the active participle "hurting" when it is she that got hurt, and she didn't do so intentionally; but we use the verb "hurt" this way often in English: "I hurt my leg". "She hurt her hand". "He hurt himself": all of these do not imply intention.