Five internal fixation methods for acetabular posterior column fracture: a finite element analysis / 中华创伤骨科杂志

ABSTRACT

Objective:To compare the biomechanical performance between 5 internal fixation methods for fracture of the acetabular posterior column using finite element analysis.Methods:One healthy female volunteer (50 years old, 160 cm in height and 63 kg in weight with a body mass index of 24.6 kg/m 2) was recruited for this study to undergo CT scan. Her CT scan data were imported into software Mimics15.0 in the format of DICOM to generate a 3D model of the pelvis. After pre-processing and accessory ligament structures added, a 3D finite element model of the pelvis was established and verified by software ANSYS. Next, software ANSYS was used to generate a model of acetabular posterior column fracture, on which models of 5 internal fixation methods (internal iliac-ischial plating, conventional posterior column plating, anterograde tensile screwing, lesser sciatic notch screwing and ischial tuberosity screwing) were established. Then stress was loaded onto the 5 internal fixation models to compare stress displacements of the fracture line on the articular surface and sites of stress concentration between the 5 internal fixation models. Results:The average stress displacement of the fracture line at the standing position was 6.13 μm for conventional posterior column plating, <6.85 μm for ischial tuberosity screwing, <7.07 μm for lesser sciatic notch screwing, <7.08 μm for internal iliac-ischial plating, and <7.85 μm for anterograde tensile screwing; the average stress displacement of the fracture line at the sitting position was 7.77 μm for conventional posterior column plating, <9.65 μm for internal iliac-ischial plating, <9.69 μm for anterograde tensile screwing,<10.1 μm for lesser sciatic notch screwing, and<10.20 μm for ischial tuberosity screwing. In all the 5 internal fixation models, the stress was chiefly concentrated at fracture ends.Conclusion:Internal iliac-ischial plating and conventional posterior column plating provide better stability than the hollow screws (anterograde tensile screwing, ischial tuberosity screwing and lesser sciatic notch screwing) for fracture of the acetabular posterior column.