What Is Causing My Daughter's Sore Knee After A Game?

My daughter (age 25) was playing softball last night, after the game she felt her right knee was getting a little sore. We she woke this morning she could not put any pressure on her right leg with out excrutiaing pain in her right knee. There is no swelling, she can bend the knee but cannot put pressure on it.

Any ideas as to what she may have injured?



Conerned Dad