Frontiers in Bioengineering and Biotechnology (Nov 2014)

Long-Term Creep Behavior of the Intervertebral Disc: Comparison between Bioreactor Data and Numerical Results

  • APG eCastro,
  • APG eCastro,
  • CPL ePaul,
  • CPL ePaul,
  • SEL eDetiger,
  • SEL eDetiger,
  • SEL eDetiger,
  • TH eSmit,
  • TH eSmit,
  • TH eSmit,
  • BJ evan Royen,
  • BJ evan Royen,
  • BJ evan Royen,
  • JC ePimenta Claro,
  • MG eMullender,
  • MG eMullender,
  • MG eMullender,
  • JL eAlves

DOI
https://doi.org/10.3389/fbioe.2014.00056
Journal volume & issue
Vol. 2

Abstract

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The Loaded Disc Culture System (LDCS) is an Intervertebral Disc (IVD)-oriented bioreactor developed by the VU Medical Center (VUmc, Amsterdam, The Netherlands), which has the capacity of maintaining up to 12 IVDs in culture, for approximately 3 weeks after extraction. Using this system, 8 goat IVDs were provided with the essential nutrients and submitted to compression tests without losing their biomechanical and physiological properties, for 22 days. Based on previous reports (Detiger et al., 2013; Paul et al., 2013, 2012), 4 of these IVDs were kept in physiological condition (control) and the other 4 were previously injected with chondroitinase ABC (CABC), in order to promote Degenerative Disc Disease (DDD). The loading profile intercalated 16h of activity loading with 8h of loading recovery to express the standard circadian variations.The displacement behavior of these 8 IVDs along the first 2 days of the experiment was numerically reproduced, using an IVD osmo-poro-hyper-viscoelastic and fiber-reinforced Finite Element (FE) model. The simulations were run on a custom FE solver (Castro et al., 2014).The analysis of the experimental results allowed concluding that the effect of the CABC injection was only significant in 2 of the 4 IVDs. The 4 control IVDs showed no signs of degeneration, as expected. In what concerns to the numerical simulations, the IVD FE model was able to reproduce the generic behavior of the two groups of goat IVDs (control and injected). However, some discrepancies were still noticed on the comparison between the injected IVDs and the numerical simulations, namely on the recovery periods. This may be justified by the complexity of the pathways for DDD, associated with the multiplicity of physiological responses to each direct or indirect stimulus. Nevertheless, one could conclude that ligaments, muscles and IVD covering membranes could be added to the FE model, in order to improve its accuracy and properly describe the recovery periods.

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