Analysis of mechanical characteristics of different screw fixation methods based on digital models of acetabular quadrilateral fracture line.

Abstract

This study aimed to hierarchically analyse the fixation effects of single and multiple screws on quadrilateral fractures in the acetabular region using finite element technology. A three-dimensional finite element model of the normal pelvis was constructed based on normal adult CT data using Mimics, Geomagic, SolidWorks, ANSYS. Six transverse equidistant fracture lines were designed for the hierarchical analysis, and five simulated human body positions were considered. We compared the mechanical properties of single and multiple screws used for fixation under various operating conditions. The results indicated a layer-by-layer decrease in the relative displacement of the fracture lines from top to bottom under different strength conditions in the standing position and the lumbar spine. In the lateral decubitus position, fracture lines 1-5 decreased layer by layer, whereas fracture line 6 increased. Moreover, in the multiple-screw model, posterior column corridor screw experienced lower stress than in the single-screw model, while blocking screws bore significantly higher stress than posterior column corridor screw. Additionally, pronounced displacement occurred along the anterior and posterior columns sides of the quadrilateral region, while the central segment showed only minor shifting under different loading states in the standing and lumbar postures; in contrast, such behavior was not observed in the lateral decubitus position. Multiple-screw fixation suggests better stability with smaller relative displacement than single-screw fixation under different loading conditions in the finite element analysis.