Review Question - QID 3604

APC II injuries are unstable injuries and occur as a result of high-energy trauma. Anatomic structures which are injured or torn include the pubic symphysis, anterior iliosacral ligaments, and the sacrotuberous ligaments. The posterior sacroiliac ligaments are spared in APC-II injuries, and differentiate an APC-II injury from an APC-III injury, in which the posterior ligaments are also torn.

Burgess et al review the classifications of pelvic ring disruptions and their association with mortality. They concluded that APC injuries required more blood replacement and were related to death more often than lateral compression, vertical shear, or combined mechanism pelvic injuries.

Tile studied the anatomy of anterior to posterior pelvic ring injuries. Although the anterior structures, the symphysis pubis and the pubic rami, contribute to 40% to the stiffness of the pelvis, clinical and biomechanical studies have shown that the posterior sacroiliac complex is more important to pelvic-ring stability. The posterior sacroiliac ligamentous complex is more important to pelvic-ring stability than the anterior structures and therefore, the classification of pelvic fractures is based on the stability of the posterior lesion.

Illustration A shows the APC classification.