Establishment and verification of a non-linear finite element model for human L4–L5 lumbar segment

Object: To establish a non-linear finite element (FE) model for human L4-L5 lumbar segment and verify its reliability. Method: A FE model of human L4-L5 lumbar segment was established. Some empirical expressions were used to simulate the mechanical properties of vertebral body. The annulus fibrosus and nucleus were assigned hyper-elastic material. The surrounding ligaments were assigned be unsymmetric spring elements. The FE model was developed in ABAQUS software under the loading conditions of axial compression, lateral bending, extension, torsion, and flexion. Result: The result curves of different loading conditions all represent a similar nonlinear curve. The axial force and displacement curve of L4-L5 FE model was closely correlated with the published results of in vitro experimental study. The relationship between moment and degrees also showed a good agreement with the experimentally determined in vitro data during the loading condition of lateral bending, extension, torsion, and flexion. Conclusion: The FE model established in this paper can effectively reflect the actual mechanical properties of human L4-L5 lumbar spine. It can be used as the basis for further research on lumbar degenerative diseases and related treatments.