The role of the nucleus pulposus in neutral zone human lumbar intervertebral disc mechanics

Department of Materials Science and Engineering, Drexel University, 3141 Chestnut Street, Philadelphia, PA 19104, USA.
Journal of Biomechanics (Impact Factor: 2.75). 02/2008; 41(10):2104-11. DOI: 10.1016/j.jbiomech.2008.04.037
Source: PubMed


To study the effect of denucleation on the mechanical behavior of the human lumbar intervertebral disc through a 2mm incision, two groups of six human cadaver lumbar spinal units were tested in axial compression, axial rotation, lateral bending and flexion/extension after incremental steps of "partial" denucleation. Neutral zone, range of motion, stiffness, intradiscal pressure and energy dissipation were measured; the results showed that the contribution of the nucleus pulposus to the mechanical behavior of the intervertebral disc was more dominant through the neutral zone than at the farther limits of applied loads and moments.

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    • "The applied compressive loads were selected to represent moderate levels of physiological stress (0.58MPa and 1.16MPa) experienced during walking or while standing and carrying an object (Wilke, Neef et al. 1999). The measured linear-region stiffness (1500 N/mm) was within the range previously reported (Brinckmann and Grootenboer 1991; Shea, Takeuchi et al. 1994; Okawa, Shinomiya et al. 1996; Beckstein, Sen et al. 2008; Cannella, Arthur et al. 2008), suggesting that our protocol and population was representative of established standards. In addition, the correlations with degeneration in this study were consistent with established literature, which has demonstrated that the disc creep rate is faster in degenerated discs (Kazarian 1975; Keller, Spengler et al. 1987; Li, Patwardhan et al. 1995; Pollintine, van Tunen et al. 2010). "
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