Abstract
When the sacrum is loaded and the pelvis is symmetrical, the primary and secondary loading forces are in balance. Any increase in posterior pelvic rotation will increase tension on the sacrotuberous ligament and increase friction and stability in the sacroiliac joints. Dysfunction may occur when the line of gravity shifts anterior to the acetabula, causing an anterior rotation of both innominates on the sacrum on an acetabular axis. This decreases tension on the sacrotuberous ligament decreasing friction in the sacroiliac joints. The force couple is disabled and the innominates will move cephalad and laterally on the sacrum moving on an acetabular axis and subluxating at the S3 segment. This may give the appearance of a multifactorial etiology or mimic the symptoms of a herniated nucleus pulposus and has many various effects on normal gait. As dysfunction of the sacroiliac joints (SIJD) is essentially always a pathological release of the self-bracing position with anterior pelvic rotation, correction of SIJD is simply manual restoration of the innominate bones caudad and medially on the sacrum back to the position of self-bracing. Correction of this subluxation will give immediate relief to at least three out of four people with low back pain.
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