Effects of finite element analysis for lumbar interbody fusion under axial loading

Methods: The study was designed to analyze the load distribution of the cancellous core after implantation of vertical ring cages made of titanium, cortical bone, and tantalum using the finite element (FE) method. The intact FE model of C5-C6 motion segment was validated with experimental results. Results: The percentage of load distribution in cancellous core dropped by about one-third of the level for the intact model after the cage implantation. The difference among cages made of different materials (or different stiffnesses) was not very obvious. Conclusions: These results implied that the influence of the cage on the load transfer in the cancellous core is greatly related to the cage's dimensions and position within the intervertebral space. The dimension and position of the cage that least disturb the load distribution in cancellous core could be criteria in cage development.