Changes in intervertebral disk mechanical behavior during early degeneration

Cornelis P.L. Paul, Kaj S. Emanuel, Idsart Kingma, Albert J. Van Der Veen, Roderick M. Holewijn, Pieter Paul A. Vergroesen, Peter M. Van De Ven, Margriet G. Mullender, Marco N. Helder, Theodoor H. Smit*

*Corresponding author for this work

Research output: Contribution to JournalArticleAcademicpeer-review

Abstract

Intervertebral disk (IVD) degeneration is commonly described by loss of height and hydration. However, in the first stage of IVD degeneration, this loss has not yet occurred. In the current study, we use an ex vivo degeneration model to analyze the changes in IVDs mechanical behavior in the first phase of degeneration. We characterize these changes by stretched-exponential fitting, and suggest the fitted parameters as markers for early degeneration. Enzymatic degeneration of healthy lumbar caprine IVDs was induced by injecting 100 μL of Chondroïtinase ABC (Cabc) into the nucleus. A no-intervention and phosphate buffered saline (PBS) injected group were used as controls. IVDs were cultured in a bioreactor for 20 days under diurnal, simulated-physiological loading (SPL) conditions. Disk deformation was continuously monitored. Changes in disk height recovery behavior were quantified using stretched-exponential fitting. Disk height, histological sections, and water- and glycosaminoglycan (GAG)-content measurements were used as gold standards for the degenerative state. Cabc injection caused significant GAG loss from the nucleus and had detrimental effects on poro-elastic mechanical properties of the IVDs. These were progressive over time, with a propensity toward more linear recovery behavior. On histological sections, both PBS and Cabc injected IVDs showed moderate degeneration. A small GAG loss yields changes in IVD recovery behavior, which can be quantified with stretched-exponential fitting. Parameters changed significantly compared to control. Studies on disk degeneration and biomaterial engineering for degenerative disk disease (DDD) could benefit from focusing on IVD biomechanical behavior rather than height and water-content, as a marker for early disk degeneration.

Original languageEnglish
Article number091008
Number of pages9
JournalJournal of Biomechanical Engineering
Volume140
Issue number9
Early online date24 May 2018
DOIs
Publication statusPublished - Sep 2018

    Fingerprint

Keywords

  • biomechanical
  • bioreactor
  • caprine
  • degeneration
  • GAG
  • glycosaminoglycans
  • intervertebral disk
  • IVD
  • lumbar
  • puncture
  • spine
  • stretched-exponential fitting

Cite this

Paul, C. P. L., Emanuel, K. S., Kingma, I., Van Der Veen, A. J., Holewijn, R. M., Vergroesen, P. P. A., ... Smit, T. H. (2018). Changes in intervertebral disk mechanical behavior during early degeneration. Journal of Biomechanical Engineering, 140(9), [091008]. https://doi.org/10.1115/1.4039890