Biomechanical analysis of the splenic avulsion mechanism.

The spleen is a frequently injured abdominal organ in road accidents, with an injury frequency close to 30%. The splenic avulsion exhibit a significant ratio of morbidity. It is clinically described as the complete failure of the pancreatico-splenic ligament (PSL) which is composed of splenic vessels and connective tissues. What are the biomechanical mechanisms involved with spleen avulsion? Is it possible to quantify tolerance levels of PSL structure? The current work combines both experimental and finite element (FE) investigations to determine the splenic avulsion process. Tensile tests on 13 PSL samples were performed up to failure. The experimental results provide reference data for model validation and showed a failure process starting at a peak force of 70±34 N combined with a peak strain of 105±26%. In an attempt to identify possible vessel ruptures within the PSL, a FE model of the PSL was developed including both vessels and connective tissues. The vessel wall behaviour up to failure was reproduced using an Ogden law and calibrated by inverse analysis according to literature data. The connective tissues function was modelled by a cohesion-loss interface. Once model correlation to experimental results was achieved, numerical simulation revealed that haemorrhage could occur even before the maximum peak is reached. Indeed, the first vessel ruptures were recorded at a strain of 92% at the upper lobe vein.