Is she wearing inserts? I have extremely flat feet and have to wear my orthodics for cheer. When your feet are flat, it actually tilts your ankle so instead of being straight across, they are offset, which in turn can make your knees twist inward and cause more knee problems, hip, and back problems. My physical therapist thought I was going to tear my ACL in cheer before I was going to do anything else to hurt myself, so I've been proactive with that and making sure I have my inserts
Go figure, the one time I didn't have them, I tore a tendon in my foot and was in a boot.