Hello Kris_sordo,
basing on the new patho-mechanical theory of
Christopher Powers (
Christopher M. Powers, PT, PhD - MoveForwardPT.com) about the patellofemoral pain, I think that the flat feet it's not the primary cause of the dislocation of the patella but it could contribute to that.
When you land on the flat foot, there is a pronation of the sub-talar joint that is mechanical coupled with an excessive external rotation of the tibia and internal rotation of the femur. These movements can increase the Q-angle and thereby increase either the pain and the lateral bowstring force on the patella.

Try to check the Christopher Powers' studies.


Best regards

Agostino