Pelvic vertical shear fractures: The damping properties of ligaments depending on the velocity of vertical impact load

Abstract

The aim of this work was to determine the influence of ligaments and soft tissue on the mechanism of pelvic injuries resulting from shear forces caused by vertical impactors with velocity in the range 1-10 m/s. The elaborated finite element model of the human pelvis (LPC) contains a bi-layered structure of bone, varying stiffness of pelvic ligaments and hyperelastic behavior of cartilage. The performed analysis indicates two limiting values: a velocity of 5 m/s as a limit for bone injuries and a velocity of 3 m/s as a limit for ligament and cartilage destruction. The ligaments having the main role in stabilizing the pelvic girdle under vertical impact load are: sacrospinous, anterior and posterior sacroiliac, iliolumbar, and inferior and posterior pubic. Obtained stress distribution in the pelvis confirms the mechanism of Malgaigne type fracture as described in the literature, indicating the transverse process as a precursor of this fracture causing the stress concentration in the lower part of the pelvis.