Biomechanical Evaluation of Transforaminal Lumbar Interbody Fusion and Oblique Lumbar Interbody Fusion on the Adjacent Segment: A Finite Element Analysis.

OBJECTIVE

To analyze the biomechanical changes of lumbar adjacent segment by comparing the biomechanics after the surgery of transforaminal lumbar interbody fusion (TLIF) and oblique lumbar interbody fusion (OLIF).

METHODS

The finite element model of the L1-S1 was reconstructed via computed tomography scan images. The models of TLIF and OLIF were constructed and analyzed. A 400-N vertical axial pre-load was imposed on the superior surface of L1 and a 10-N·m moment was applied on the L1 superior surface along the radial direction to simulate 4 different physiological motions: flexion, extension, bending, and torsion. The range of motion (ROM) and the intradiscal pressure (IDP) were evaluated and compared with investigate the biomechanical influences of TLIF and OLIF on the adjacent segments (L3-L4 and L5-S1).

RESULTS

Compared with the normal model, TLIF and OLIF in all motion patterns increased the ROM and the IDP of adjacent segments. However, the ROM and the IDP between TLIF and OLIF had no significant difference.

CONCLUSIONS

The biomechanical analysis showed that both TLIF and OLIF can increase ROM and IDP. It indicates that TLIF and OLIF probably increase the potential risk of adjacent segment degeneration similarly.