Single iliac screw and dual iliac screws and titanium mesh cage fixation in the reconstruction of lumbosacral defects with finite element analysis / 中国组织工程研究

ABSTRACT

BACKGROUND:The surgical management to reconstruct the stability in lumbosacral region is very chal enging. There are many techniques to reconstruct the stability of the lumbosacral region, but the internal fixation loosening, fracture and pseudoarthosis are not uncommon. OBJECTIVE:Finite element analysis was used to analyze the stability of two types of reconstruction procedures and the stress of the internal fixation system. METHODS:A 64-slice spiral CT scan was used in a subject from L1 to pelvis. The scan data were imported into the Mimics 15.0 software to generate a three-dimensional surface model. The three-dimensional solid model was established using in the SolidWorks software. The solid geometry model of the L3, 4 pedicle screws combined with single iliac screw fixation and L3,4 pedicle screws combined with dual iliac screws and anterior titanium mesh cage support fixation were constructed by the Solidworks software. Two kinds of reconstruction procedures were simulated. The models were given material properties and analyzed by using the ABAQUS software. RESULTS AND CONCLUSION:(1) The maximum stress was 195.3 MPa in the complete model, 189.5 MPa in single iliac screw model, and 149.2 MPa in dual iliac screw+titanium cage model when constrained the roof of double acetabulum and applied a vertical load of 1 000 N. (2) The axial compression rigidity was 551.572 N/mm in the complete model, 613.87 N/mm in the single iliac screw model and 1 683.50 N/mm in the dual iliac screw+titanium cage model. (3) The bending rigidity of the dual iliac screw+titanium cage model was bigger than other models at 6 directions when applied 7 N?m bending loads. The maximum stress of single iliac screw model was bigger than other models. (4) The results suggest that the dual iliac screw+titanium mesh cage reconstruction can effectively restore the stability of the lumbosacral area. The stress of internal fixation system is smal er and more dispersed. There is obvious stress concentration in the connecting rod and the tail of the single iliac screw. The single iliac screw internal fixation system is easy to fatigue fracture and loosening.