These accessory movements of the sacroiliac joint are not under voluntary control; they are necessary, however, for full painless function of the joint and full range-of-motion of the joint. Sacroiliac Joint dysfunction signifies a loss of JOINT PLAY movement. The existence of joint play movement is necessary for pain free voluntary movement to occur. If the JOINT PLAY movement is found to be absent, this movement must be freed before functional voluntary movement can be fully restored. This is best done by skilful manipulation.