Journal of biomechanical engineering
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A simplified in vitro model of the spinal canal, based on in vivo magnetic resonance imaging, was used to examine the hydrodynamics of the human spinal cord and subarachnoid space with syringomyelia. In vivo magnetic resonance imaging (MRI) measurements of subarachnoid (SAS) geometry and cerebrospinal fluid velocity were acquired in a patient with syringomyelia and used to aid in the in vitro model design and experiment. The in vitro model contained a fluid-filled coaxial elastic tube to represent a syrinx. ⋯ LDV measurements indicated that spinal cord wall motion was nonaxisymmetric with a maximum displacement of approximately 140 microm, which is below the resolution limit of MRI. Agreement between in vivo and in vitro MR measurements demonstrates that the hydrodynamics in the fluid filled coaxial elastic tube system are similar to those present in a single patient with syringomyelia. The presented in vitro study of spinal cord wall motion, and complex unsteady pressure and flow environment within the syrinx and SAS, provides insight into the complex biomechanical forces present in syringomyelia.
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Comparative Study
Dependence of mechanical behavior of the murine tail disc on regional material properties: a parametric finite element study.
In vivo rodent tail models are becoming more widely used for exploring the role of mechanical loading on the initiation and progression of intervertebral disc degeneration. Historically, finite element models (FEMs) have been useful for predicting disc mechanics in humans. However, differences in geometry and tissue properties may limit the predictive utility of these models for rodent discs. ⋯ Notably, the model was able to produce spatial variations in nucleus pulposus matrix consolidation that are consistent with previous observations in nuclear cell morphology made in mouse discs using confocal microscopy. Results of this study emphasize the need for including nucleus swelling pressure, collagen viscoelasticity, and fluid permeation when simulating transient changes in matrix and fluid stress/strain. Sensitivity analyses suggest that further characterization of nucleus pulposus material properties should be pursued, due to its significance in steady-state and transient disc mechanical response.