Hi Lauren, I saw your comment on Doug K's whiteboard and thought I could help

 I had a similar prob about 10 yrs ago. Both patellas subluxed between 15-20 times each knee during my first season playing college football.

8 yrs ago, I had surgery on both knees to correct an "anatomical" problem - Patella Alta - Basically, my kneecaps sat too high and this made them prone to subluxation.

 Do you have a structural problem that NEEDS to be fixed by surgery?

If not, and the problem is a weak VMO coupled most likely with tight lateral quads, IT band and hipp abductors, then you may be able to get away with soft tissue therapy & strength work.

I can't help you with the diagnosis or most of this soft tissue work, but I can help you strengthen the VMO (BTW, if a physio has you doing any type of step-up to hit the VMO, you are wasting your time)

Try this - stand with your back to a wall - with a stability/swiss ball behind one of your knees. Your knee is bent between 10 and 20% of full flexion. Brace your body against something (a chair, another wall) and  push back with your bent leg. The resistance of the stability ball should make it hard to straighten your leg. Perform multiple sets of 5 reps

You may also want to look at loosening up your it band, quads, lateral thigh musculature and hips with a hard foam roller - look up Eric Cressey here at wellsphere - he has great info on his blog

Message me if you have any questions