Acetabular retroversion has recently been suspected of being an important factor in the development of femoral acetabular impingement and hip osteoarthritis. The proper function of the hip joint requires that the anatomic features of the acetabulum and femoral head complement one another. In acetabular retroversion, the alignment of the acetabulum is changed where it opens in a posterolaterally rather than anterior direction. Changes in acetabular orientation can occur with alterations in pelvic tilt (anterior/posterior), and pelvic rotation (left/right). A problem that alters pelvic tilt and rotation often seen by physical therapists is sacroiliac joint dysfunction, though it does not receive enough attention. A unique feature that develops in patients with sacroiliac joint dysfunction (SIJD) is asymmetry between the left and right innominate bones that can change pelvic tilt and rotation. This article puts forth a theory proposing that acetabular retroversion may be produced by sacroiliac joint dysfunction.