re 1: As I understand it when testing hip range of motion passively you go to the point where the joint is restricted, not to the point where you can force the joint to. In other words when testing ROM in the hips you do so with fairly light manipulation on a relaxed patient to see where the joints are restricted. There is no pain at the point where the physio stops, and there is no pain when I actively rotate the joint. If the joint is forced into more IR than it’s capable of I feel impingement in the front of the hip.
Wolff’s law is a theory that states that bone in a healthy person or animal will adapt to the loads under which it is placed. Given the nature of impingement in the hip joint, if a healthy person (or animal) starts to use a range that was previously blocked by boney impingement is there a point to which the the impingement has gone too far and attempting to go against it will only damage the joint?