As a result, there is very little movement at the sacroiliac joint.Listed below are the major reasons for pain around the sacroiliac joint:Muscle tightnessPregnancy: the pelvis widens to prepare for birth, stretching the ligaments -- strong, flexible tissue that connects bone to boneDifferent types of arthritis that causes SIJ painTypes of arthritis that causes SIJ painAnkylosing spondylitis is a