Three-dimensional finite-element analysis of a pedicle screw system combined with a titanium mesh support and fixation in the treatment of L4-5 vertebral tuberculosis.

Abstract

This study aimed to assess the biomechanical stability of pedicle screws combined with titanium mesh bone grafting for spinal reconstruction and fixation during surgery for lumbar spine (L4-L5) tuberculosis using the finite-element method. A model of the L1-sacral segment of the human body was developed using the finite-element method. After verifying its effectiveness, a postoperative model was developed for treating vertebral tuberculosis at the L4-L5 level, which involved implanting an interbody titanium mesh and securing it with pedicle screws. Subsequently, the internal fixation materials and bone stress at L4 and L5 were analyzed. The verification of the finite element model proved to be effective. The titanium mesh exhibited a maximum von Mises stress of 477.9 MPa during forward bending and a minimum of 229.9 MPa during backward extension. The stress concentration was primarily observed at the cut edges, screws, and connections. Similarly, the rod experiences a maximum stress of 235.8 MPa when leaning to the right and a minimum of 101.4 MPa during backward extension. High-stress areas were identified on the screws and connecting rods. In the titanium mesh model, the maximum von Mises stresses on L4 and L5 reached 215.9 MPa during forward bending and exceeded 90 MPa in five directions. In the treatment of lumbar tuberculosis, titanium mesh fusion and pedicle screw-reinforced fixation carry the risk of prosthesis subsidence and screw breakage. Therefore, patients receiving this treatment should be cautious and avoid excessive forward and lateral flexion movements.