The Influence of Double-Headed Screws on Stability of Multi-Rod Structures in Posterior Three-Column Spinal Osteotomy
Objective To compare the stability of multi-rod structures with double-headed screws and traditional connectors in posterior three-column osteotomy of the spine using finite element analysis.Methods A finite element model of the T3-L4 thoracolumbar spine was constructed based on postoperative computed tomography(CT)data of patients with severe kyphosis.Based on the patient's standard two-rod model(2R),a double-headed screw multi-rod structure model(4R-DHS)and a traditional connector multi-rod structure model(4R-TC)were constructed.The two models were evaluated under 300 N follower load and 7.5 N-m moment load,and the stability,maximum von Mises stresses on the main rods,and stress distributions of the two multi-rod structures were analyzed.Results There was little difference in the stability between the two multi-rod structures.Compared with 4R-TC,4R-DHS showed a decrease in the maximum von Mises stresses on the main rods during all motions(the stress decreased by 7.2％,8.8％,8.7％,18.5％,and 16.9％during flexion,left lateral bending,right lateral bending,left axial rotation,and right axial rotation,respectively)and more uniform stress distribution,except for a slight increase in the maximum von Mises stresses on the main rods during post-extension.Conclusions The double-headed screw multi-rod structure can reduce the maximum stress on the main rod compared with the traditional connector multi-rod structure,and there is no problem with stress concentration on the main rod near the connector,which can more effectively reduce the risk of internal fixation failure.
three-column osteotomydouble-headed screwconnectorfinite element analysis
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