Background: Anterior lumbar interbody fusion (ALIF) and posterior lumbar interbody fusion (PLIF) surgery using one cage have been shown to have similar biomechanics compared to the use of two cages. However, there have been no reports on the biomechanical differences between using one versus two cages in transforaminal lumbar interbody fusion (TLIF) surgery.
Objective: To determine the biomechanical differences between the use of one versus two cages in TLIF by finite element analysis.
Methods: Three validated finite element models of L3-L5 lumbar segment were created [intact model (INT), single cage and paired cages TLIF models]. To study the biomechanics, a compressive preload of 400 N over 7.5 N-m was applied to the superior surfaces of the L3 vertebral body to simulate flexion, extension, rotation, and lateral bending.
Results: There was no significant difference in the range of motion between single cage and paired cages TLIF models, less than 1[degrees] for all loading cases. Cage stress was high in the single cage TLIF model under all loading conditions. Bone graft stress was high in the single cage TLIF model. Pedicle screw stress was higher in single cage versus paired cages TLIF.
Conclusion: Single cage TLIF approximates biomechanical stability and increases the stress of the bone graft. The use of a single cage may simplify the standard TLIF procedure, shorten operative times, decrease cost, and provide satisfactory clinical outcomes. Thus, single cage TLIF is a useful alternative to traditional two cage TLIF.
From: Biomechanical Comparison of Transforaminal Lumbar Interbody Fusion With One or Two Cages by Finite Element Analysis by Xu et al.