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) twoscrew 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.

Background This study aimed to compare the biomechanical differences between anterior cervical discectomy and fusion (ACDF) with multiple-level separate plates and conventional long plates by using finite element analysis. Methods The following four finite element models were created to simulate various fixations: (1) C4–6 ACDF with multiple plates, (2) C4–6 ACDF with a single plate, (3) C3–6 ACDF with multiple plates, and (4) C3–6 ACDF with a single plate. The maximum Von-mises stress of the cage and fixation, compressive force of the adjacent intervertebral discs and range of motion (ROM) of different segments in the four models were calculated and analyzed. Results For C4–6 ACDF, the maximum Von-mises stress of the cage and fixation was lower in the multiple plate fixation model in all motion states. Similarly, for the C3–6 ACDF models, the peak stress of the C3–4 and C5–6 cages was lower with multiple plates fixation in all motions but the stress of the C4–5 cage in the multiple plates model was slightly higher in flexion, bending and rotation. Besides, applying multiple plates in C3–6 ACDF models resulted in a decreased maximum stress of the fixation under different motions except for bending. In both the C4–6 ACDF and C3–6 ACDF models, the ROM values of the adjacent motion segments were lower in the multiple plates models in extension, bending and rotation. In the C4–6 ACDF models, the peak stress on the adjacent intervertebral discs in the multiple plates models was slightly smaller. In C3–6 ACDF models, the maximum stress on the adjacent intervertebral discs was larger in the single-plate model under flexion, bending and rotation movements. Conclusion Multiple plates fixation has a positive effect on increasing stiffness and maintaining the ROM of adjacent segments, indicating lower risk of construct failure and adjacent segment degeneration. Further studies are required to confirm its efficacy in clinical practice.