[2] The SIJ's stability is maintained mainly through a combination of only some bony structure and very strong intrinsic and extrinsic ligaments.

[8] The ridge and corresponding depression, along with the very strong ligaments, increase the sacroiliac joints' stability and makes dislocations very rare.

The fossae lumbales laterales ("dimples of Venus") correspond to the superficial topography of the sacroiliac joints.

The long dorsal sacroiliac joint ligaments run in an oblique vertical direction while the short (interosseous) runs perpendicular from just behind the articular surfaces of the sacrum to the ilium and functions to keep the sacroiliac joint from distracting or opening.

With sacroiliitis, the individual may experience pain in the low back, buttock or thigh, depending on the amount of inflammation.

When the provocative maneuvers reproduce pain along the typical area, it raises suspicion for sacroiliac joint dysfunction.

The diagnosis is confirmed when the patient reports a significant change in relief from pain and the diagnostic injection is performed on 2 separate visits.

[15][16][17] The hormonal changes of menstruation, pregnancy, and lactation can affect the integrity of the ligament support around the SIJ, which is why women often find the days leading up to their period are when the pain is at its worst.

[citation needed] Muscle imbalance, trauma (e.g., falling on the buttock) and hormonal changes can all lead to SIJ dysfunction.

Women are considered more likely to suffer from sacroiliac pain than men, mostly because of structural and hormonal differences between the sexes, but so far no credible evidence exists that confirms this notion.

Female anatomy often allows one fewer sacral segment to lock with the pelvis, and this may increase instability.