Biomechanical comparison of posterior lumbar interbody fusion and transforaminal lumbar interbody fusion with two straight-shaped cages by finite element analysis

Abstract

Abstract Background Previous biomechanical studies have compared posterior lumbar interbody fusion (PLIF) and transforaminal lumbar interbody fusion (TLIF), however the cages used in TLIF/PLIF surgery are different. Therefore, comparing the two surgical procedures with the same fusion cages is more reflective of the real differences between the two procedures. This study was to compare the biomechanical effects between PLIF and TLIF with placing two straight-shaped cages using finite element analysis. Material/Methods: A previously validated intact L3-L5 lumbar spine finite element model was modified to simulate two straight-shaped cages PLIF and two straight-shaped cages TLIF. A moment of 7.5 N-m with a compressive preload of 400 N was applied on the L3 vertebra to test the range of motion (ROM) and stress. Results There were no significant differences in the ROM between PLIF and TLIF with less than 1 degree for all loading cases. We found that stress of cage, and stress of L4 endplate were high in PLIF, and stress of pedicle screw was high in TLIF. Similar bone graft stress was found in PLIF and TLIF. Conclusions The biomechanical result indicated that both TLIF and PLIF can acquire similar ROM and bone graft stress. PLIF increases the stress of cage and L4 inferior endplate, and pedicle screw stress was high in the TLIF model. The findings of our study need to be verified through further clinical studies that explore differences between the two methods.