Finite Element Modeling And Biomechanical Analysis Of Lumbar Disc Degeneration

Finite element modeling and biomechanical analysis of lumbar disc degeneration【Objective】To establish a finite element model of L4-5 motion segment with disc degeneration and to evaluate the effects of disc degeneration on biomechanical behavior of human lumbar spine segments.【Methods】The experiment used a finite element analysis software Super—Sap to create a finite element model of L4-5 motion segment with non-degenerated disc(normal disc model, NDM). Then, a finite element model of spine segment with disc degeneration (degenerated disc model, DDM)was established through changing the material properties of disc tissues. The biomechanical parameters of two models such as the displacement and the stress level of disc, facet loadings was measured under 1500N axial compressive load.【Results】(1) In the condition of axial pressure, both disc axial displacement and posterolatera] disc bulge obviously decrease after disc degeneration(P＜0.01). (2) In the condition of axial pressure, axial compressive pressure of both end-plate and outer annular fibrosus increases after disc degeneration(P＜0.01); Otherwise, both interdiscal pressure and axial compressive pressure of inner annular fibrosus differ little after disc degeneration(P＞0.05). (3) In the condition of axial pressure, yon mises stress of both inner and outer annular fibrosus increases after disc degeneration(P＜0.01); Otherwise, yon mises stress of end-plate differs little after disc degeneration(P＞0.05). (4) In the condition of axial pressure, the relative displacement, axial compressive stress and yon mises stress of facets decrease after disc degeneration(P＜0.01).【Conclusions】(1) The stiffness of disc and motion segment obviously increases after disc degeneration. (2)Accroding to the spine three -columns mechanical theory, the loadings of anterior and central columns increase but the loading of posterior column decreases after disc degeneration. (3)The risk of disruption in both inner and outer annular fibrosus increases after disc degeneration.