Servizio Comunitario di Informazione in materia di Ricerca e Sviluppo - CORDIS

Finite element model

Intervertebral discs have a primarily mechanical role in transmitting loads through the spine. The disc is subjected to a combination of elastic, viscous and osmotic forces; previous models have typically neglected osmotic forces. The fibril-reinforced poroviscoelastic swelling model of Wilson, which has recently been developed in our group, is used to compute the interplay of osmotic, viscous and elastic forces in an intervertebral disc under axial compressive load.

The unloaded 3D finite element mesh equilibrates in physiological solution, exhibiting an intradiscal pressure of about 0.2 MPa. Before and after axial loading the simulated hydrostatic pressure compares well with the experimental ranges measured. Loading the disc decreases the height of the disc and results in an outward bulging of the outer annulus. Fiber stresses are highest on the most outward bulging on the posterior-lateral side. The osmotic forces resulted in tensile hoop stresses, which are higher than typical values in a non-osmotic disc. The computed axial stress profiles reproduced the main features of the stress profiles, in particular the characteristic posterior and anterior stress peaks, which were observed experimentally by McNally et al.

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POB 513 Den Dolech 2