A subluxation of the Ilio-sacral joint automatically produces a tilt of the sacrum. Formerly I called this process subluxation of the sacrum and nowadays tilt of the sacrum, because the latter term describes the process better.
The Ilio-sacral joints are tilting joints. The tilting axis runs laterally across the sacrum and is positioned at the same level as the right and the left Spina iliaca superior posterior, which means that the upper part of the sacrum is small and the lower part of the sacrum is relative large. This means that the tilting forward of the upper shorter part of the sacrum is less than the movement backward of the longer lower part of the sacrum.
When the sacrum tilts in its upper part, the upper part of the sacrum moves forward and the lower part backwards. This always happens one-sided, i.e. at the side of the heaviest subluxation of the Ilio-sacral joint. The side of the subluxation of the Ilio-sacral joint changes in the course of time and with it also the tilting of the sacrum.