If you mean "rotated sacrum" the current theory is that that has played a role in the shoulder dystocias I've experienced because a rotated sacrum can't swing back normally. For me, physical therapy has made a tremendous difference in terms of pelvic stability.
Catholic wife in with my husband, mom to x5, x2, x6. Birther of babes, baker of bread, and connoisseur of human folly. WINNER OF THE SILVER BIRTH STOOL, APRIL 2010 DDC! Happily hospital birthing with my BFF, Epidural Man.