Anatomical consequences of open-book pelvic ring disruption : A cadaver experimental study

"Open-book" pelvic fractures associate a diastasis and/or a fracture of the pubic rami with a posterior pelvic disruption of the sacro-iliac joint. These uni or bilateral lesions are potentially lethal mainly due to associated injuries and massive pelvic hemorrhage. The most frequently injured arteries are parietal branch of the commune, internal or external arteries because of their proximity to the bone, the sacro-iliac joint and the inferior ligaments of the pelvis. The pelvic bone dislocation and the increase of pelvic volume facilitate blood effusion. The aim of this study was to determine, on a cadaver fracture model, the direct anatomical consequences of "open-book" pelvic fracture on the ilio-lumbar pedicle and the pelvic cavity volume. Bilateral open-book pelvic ring injuries were created in ten non-embalmed cadaver specimens by directly disrupting the pubic symphysis, the right and the left sacro-iliac joints. Pelvic volume was determined after total pelvic exenteration. Consequences of this fracture on vascular parietal network, nervous pelvic trunk and pelvic cavity volume were studied. The mean volume of the pelvic cavity after complete visceral exenteration was 872.5 cm(3) (extremes 580-756 cm(3)). The average increase of pelvic volume was 20.8% after 5 cm of pubic diastasis. In all cases, because of a transversal disposition of the ilio-lumbar pedicle with regard to the sacro-iliac joint, reproduction of the open-book fracture caused a venous dilaceration of the ilio-lumbar vein in 12 cases after 5 cm of pubic diastasis (12/20=60%). No arterial dilaceration was observed on the ilio-lumbar artery, but this artery was put in tension. Open-book fractures create an increase of pelvic volume that facilitates blood diffusion from parietal pelvic vascular network. Ilio-lumbar pedicle seems to be very vulnerable in this type of fracture because of its relations to the sacro-iliac joint and its transversal disposition with regard to this joint.