Dear Alophysio:
I believe that Ola Grimsby, as numerous others, has advocated and I believe has proved that theSIJ does move.
I have no problem with the concept. After all, why would a joint be where it is unless there was some sort of movement???
The innominate bones move relative to the sacrum and to each other. That is well attested to.
The test assesses movement not a "stuck" joint. It shows that the concept of "stuck' is not so. It shows a different cause than proposed by the "stork" test.
I am not sure why this is asked.
Best regards,
Neuromuscular