Knee injuries are so common among dancers, and I've found several articles that can help you diagnose which injury you have if you have knee pain. This is also very helpful for us teachers so we can be knowledgeable about common knee injury causes and fixes. Several of my dancers suffer from knee pain on a regular basis, and I have to keep a very watchful eye on their turnout and their use of the plie when they land jumps. But, those aren't the only ways to prevent knee injuries, as you'll see in this article from Dance Spirit Magazine - "Beating Common Knee Injuries". Another good article can be found on Dance Magazine's website: On Dance Injuries: The Jumper's Knee.