Biomechanical evaluation of a novel anatomical plate for oblique lumbar interbody fusion compared with various fixations: a finite element analysis.

Background: To build a model of an anatomical plate for oblique lumbar interbody fusion (OLIF) surgery based on previous anatomical parameters and verify the biomechanical effect with finite element analysis. Methods: The anatomical plate model was built with AutoCAD and Solidworks. Finite element models of the L2-3 and L4-5 segments were established with computed tomography images from a 46-year-old asymptomatic male individual. Six fixation technique models were created: (I) stand-alone (SA); (II) bilateral pedicle screws (BPS); (III) lateral rod-screw (LRS); (IV) lateral rod-screw plus facet screw (LRSFS); (V) two-screw lateral plate (TSLP); (VI) anatomical plate. The range of motion (ROM), the cage stress, and the instrument stress were calculated under different motion states. Results: In the L2-3 and L4-5 segment models, except for a slightly higher maximum cage stress in the extension state of the TSLP model and the right bending and rotation states of the BPS model, the maximum cage stress in each model was smaller than that of the SA model. In the L2-3 and L4-5 segments, each internal fixation limited the ROM in each motion state. The anatomical plate was more effective in reducing the maximum cage stress and vertebral ROM than the two-screw plate. Three-dimensional finite element analysis did not find a higher risk of construct failure for the anatomical plate model compared with the BPS internal fixation model. Conclusions: Anatomical plates can be considered as supplementary fixations using a single incision and position to improve the stability and rigidity of the construction and reduce the risk of complications.