How the cylindrical girdle affects sacroiliac. The intermediary cylindrical girdle is the go-between for the sacroiliac. Since the sacroiliac does not have support, yet it permits a variety of turns and twists, it needs an intermediary to hold it up. The sacroiliac connects with the ilium and sacrum at the upper area of the hipbone or ilium and the joints between the ilium and sacrum. Now, if this girdle is interrupted it can cause a disease known as muscular dystrophy. The disease is crippling. MD is characterized by plodding waste of the skeletal muscles.