Journal of the mechanical behavior of biomedical materials
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J Mech Behav Biomed Mater · Mar 2018
Temporal and spatial variations of pressure within intervertebral disc nuclei.
Experimental and computational studies often presume that nuclei pulposi of non-degenerated human lumbar discs function as fluid-filled cavities with single hydrostatic pressures throughout that vary neither with time nor location and orientation. Recent simultaneous measurements of the pressure at multiple locations within disc nuclei have however shown time-dependent and nonhomogeneous pressure distributions. This combined in vitro and in silico study aims to re-examine the temporal and spatial variations of the pressure within disc nuclei with special focus on the effect of tissue hydration. ⋯ With time and as the pore pressure drops, the contribution of the nucleus bulk increases till it reaches equilibrium. The relative share of the annulus bulk in supporting the applied loads markedly increases not only with time but at higher loads and lower hydrations. The hydration state of the disc is hence crucial in the disc pressure distribution and internal response under various static-dynamic loads in vitro and in the replication of in vivo conditions.