Design and Stress Analysis of Wider Lateral Lumbar Interbody Fusion (LLIF) Cages: A Finite Element Study

Abstract

It is important to better understand the impact of intervertebral cage material and design on the stress distribution in vertebral bodies to aid eliminate complications like subsidence and improve performance after lumbar interbody fusion. In this study, the cage materials of PLA, PEEK, titanium, and stainless steel were compared using a finite element model of the L3-L4 motion segment. Strain and stress were measured in the vertebra and cage when the model was loaded in axial compression, flexion, and torsion. Additionally, a wider cage designed to conform to the vertebral endplates could potentially evenly distribute and reduce the overall stress at the endplates. The wider cages increased the area in contact with the bone, distributing the stress more evenly and providing a potential way to decrease the danger of subsidence. Such cages could be manufactured by additive manufacturing.