Influence d'un implant facettaire auxiliaire sur la biomécanique du rachis lombaire

Abstract : Lumbar stenosis and facet osteoarthritis represent the main indications for facet replacement. The purpose was to analyze the influence of a novel Auxiliary Facet System (AFS) on lumbar spine biomechanics. Kinematic in vitro experiments had demonstrated that the AFS has a minor influence on range of motion in flexion-extension and lateral bending at the instrumented level L4-L5. Facetectomy led to a major increase in axial rotation, which was reduced by the AFS because of the implant's crosslink. This limitation of hypermobility represents the major role of the implant. The instrumented disc has been studied in vitro by measuring intradiscal pressures and using a finite element model. The AFS decreased intradiscal pressures in flexion-extension. Von Mises stress at the annulus was similar after AFS instrumentation and after lesion by facetectomy and undercutting laminectomy. Fusion decreased annulus stress at the instrumented level better than the AFS. At the adjacent segments, a similar behavior was observed between the AFS and the intact spine in flexion-extension and lateral bending, whereas fusion increased annulus stress and peak contact forces at adjacent facet joints. In axial rotation, the AFS and fusion increased annulus stress and facet peak contact forces similarly. An in vitro shear loading experiment simulated beginning degenerative spondylolisthesis. The lesion decreased shear stiffness and increased anterior displacements, whereas the shear properties were similar between the AFS instrumented segment and the intact spine.
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Contributor : Yann Philippe Charles <>
Submitted on : Friday, September 28, 2012 - 9:32:13 AM
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  • HAL Id : pastel-00736335, version 1

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Yann Philippe Charles. Influence d'un implant facettaire auxiliaire sur la biomécanique du rachis lombaire. Biomécanique [physics.med-ph]. Arts et Métiers ParisTech, 2012. Français. ⟨NNT : 2012ENAM0032⟩. ⟨pastel-00736335⟩

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