Biomechanical comparison of a new stand-alone anterior lumbar interbody fusion cage with established fixation techniques- a three-dimensional finite element analysis
Initial promise of a stand-alone interbody fusion cage to treat chronic backache and restore disc height has not been realized. Others have used a posterior spinal fixation in conjunction to enhance stability and promote fusion rate.
Presently, a new stand-alone cage is compared with conventional fixation methods based on the finite element analysis, investigating cage-bone interface mechanics and stress distribution on the adjacent tissues.
Methods: Three trapezoid 8-degree interbody fusion cage models (dual paralleled cages, a single large cage, or a two-part cage consisting of a trapezoid box and threaded cylinder) were created and accompanied with or without pedicle screws fixation to investigate their relative importance on the spinal segmental response.
The contact stress on the facet joint, slip displacement of the cage on the endplate, and rotational angle of the upper vertebra were measured under different loading conditions.
Results: Simulation results demonstrated less facet stress and slip displacement under the maximal contact on the cage-bone interface. A stand-alone two-part cage had good slip behavior under compression, flexion, extension, lateral bending and torsion, as compared with the other two interbody cages, even with the additional posterior fixation.
However, this cage alone had the lowest rotation angles under flexion and torsion, but had no differences under extension and lateral bending.
Conclusions: Biomechanical benefit of a stand-alone two-part fusion cage is justifiable.
This device provides the stability required for interbody fusion, supporting clinical trials alternative to circumferential fixations.
Author: Shih-Hao Chen, Ching-Lung Tai, Chien-Yu Lin, Pang-Hsing Hsieh and Weng-Pin Chen
Credits/Source: BMC Musculoskeletal Disorders 2008, 9:88
Published on: 2008-06-18
Copyright by the authors listed above - made available via BioMedCentral (Open Access). Please
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