I am not sure I buy this reason. First off you are saying that the DDF is pulling the third phalex down . It is my understanding that the only time this would happen is if the heels are trimed to short and then put stess on the tendon. It is also my understanding that laminitis is a metabolic diease and is associated with endotoxemia. Lactic acid in the blood increases in concentration when they founder.
Endotoxins cause histamine formation and blood platelet function is impaired.
Blood flow to the sensitive laminae is disturbed and the cornification process is disrupted. The secondary laminae become necrotic and then phalex 3 rotates or sinks and pulls away from the hoof wall. The foot has not foundered until it has rotation. In my humble opinon the cause of the pain is from the rotation and the lack of oxygen in the tissues.