The internal mechanics of the intervertebral disc under cyclic loading

P.E. Riches, N. Dhillon, J. Lotz, A.W. Woods, D.S. McNally

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    The mechanics of the intervertebral disc (IVD) under cyclic loading are investigated via a one-dimensional poroelastic model and experiment. The poroelastic model, based on that of Biot (J. Appl. Phys. 12 (1941) 155; J. Appl. Mech. 23 (1956) 91), includes a power-law relation between porosity and permeability, and a linear relation between the osmotic potential and solidity. The model was fitted to experimental data of the unconfined IVD undergoing 5 cyclic loads of 20 min compression by an applied stress of 1 MPa, followed by 40 min expansion. To obtain a good agreement between experiment and theory, the initial elastic deformation of the IVD, possibly associated with the bulging of the IVD into the vertebral bodies or laterally, was removed from the experimental data. Many combinations of the permeability-porosity relationship with the initial osmotic potential (πi) were investigated, and the best-fit parameters for the aggregate modulus (HA) and initial permeability (ki) were determined. The values of HA and ki were compared to literature values, and agreed well especially in the context of the adopted high-stress testing regime, and the strain related permeability in the model.
    Original languageEnglish
    Pages (from-to)1263-1271
    Number of pages8
    JournalJournal of Biomechanics
    Issue number9
    Publication statusPublished - 2002


    • intervertebral disc
    • poroelastic
    • pharmacology
    • biomedical sciences
    • physiology


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