Common knee injuries among dancers?

I'm a ballet dancer, and I have severe bow legs that sometimes cause me a lot of pain. I'm currently in a summer intensive which has reaally exacerbated my knee pain to the point where I sometimes can't walk...Pointe class hurts the most, however they won't let me skip the class or take the class on flat unless I have an actual diagnosable injury. Now, I knoow this is bad, but is there any sort of very common knee injury in dancers that I can say I have to get out of at least pointe? The SI is over at the end of the week, but I'm afraid if I push it I might actually really hurt myself and not be able to perform in their show.