Fibre-matrix interaction in the human annulus fibrosus

Area of Science:

• Biomechanics
• Biomaterials Science
• Computational Mechanics

Background:

• The mechanical behavior of the human annulus fibrosus is crucial for spinal health.
• Existing constitutive models often overlook the complex interaction between collagen fibers and the ground matrix.
• Understanding this interaction is key to developing more accurate models.

Purpose of the Study:

• To investigate the significance of fiber-matrix interaction in the human annulus fibrosus.
• To analyze experimental data, theoretical models, and numerical simulations from existing literature.
• To elucidate the role of this interaction in the overall mechanical response.

Main Methods:

• Review and analysis of experimental data (biaxial and uniaxial tests).
• Evaluation of theoretical constitutive models, including incompressible neo-Hookean type models.
• Assessment of numerical simulation results from the literature.

Main Results:

• The ground matrix's mechanical behavior is accurately simulated by an incompressible neo-Hookean model.
• Matrix stiffness is dependent on fiber stretch ratio, indicating fiber-matrix interaction.
• This interaction is anisotropic, varying with fiber distribution and direction.
• Fiber orientation dispersion explains the matrix's tangent stiffness dependence on the deformation tensor's first invariant.

Conclusions:

• Fiber-matrix interaction significantly influences the mechanical behavior of the annulus fibrosus.
• Anisotropic interactions and fiber orientation dispersion are critical factors.
• Accurate constitutive models must incorporate these fiber-matrix interactions for improved biomechanical predictions.