Posterior facet load changes in adjacent segments due to moderate and severe degeneration in C5-C6 disc: a poroelastic C3-T1 finite element model study.

Study Design: Biomechanics of normal vertebral segments adjacent to a degenerated segment in the cervical spine.

Objective: To test the hypothesis that posterior facet joints of adjacent segments are loaded more when degeneration occurs in the intermediate disc segment.

Summary Of Background Data: Degeneration progression in adjacent segments is a clinical concern.

Simulation of inhomogeneous rather than homogeneous poroelastic tissue material properties within disc annulus and nucleus better predicts cervical spine response: a C3-T1 finite element model analysis under compression and moment loadings.

Study Design: A finite element (FE) modeling of homogeneous and inhomogeneous poroelastic tissue material properties within disc anulus fibrosus (AF) and nucleus pulposus (NP).

Objective: To test the hypothesis that simulation of inhomogeneous poroelastic tissue material properties within AF and NP quadrants, rather than homogeneous properties within regions of AF and NP without quadrants, would better predict the cervical spine biomechanics.

Summary Of Background Data: In order to represent tissue swelling and creep deformation behavior more physiologically in FE models, disc poroelastic tissue material properties should be modeled appropriately.

Relative contributions of strain-dependent permeability and fixed charged density of proteoglycans in predicting cervical disc biomechanics: a poroelastic C5-C6 finite element model study.

Disc swelling pressure (P(swell)) facilitated by fixed charged density (FCD) of proteoglycans (P(fcd)) and strain-dependent permeability (P(strain)) are of critical significance in the physiological functioning of discs. FCD of proteoglycans prevents any excessive matrix deformation by tissue stiffening, whereas strain-dependent permeability limits the rate of stress transfer from fluid to solid skeleton. To date, studies involving the modeling of FCD of proteoglycans and strain-dependent permeability have not been reported for the cervical discs.