A mechanistic damage model for ligaments.

Area of Science:

• Biomechanics
• Biomaterials Science
• Computational Biology

Background:

• Biomechanical models require realistic tissue representation for accuracy.
• Existing phenomenological ligament models often neglect behavior in the failure region.
• A mechanistic approach is needed to capture complex ligamentous tissue responses.

Purpose of the Study:

• To test a mechanistic ligament model against experimental data.
• To evaluate the model's ability to represent ligament failure behavior.
• To assess the model's performance under cyclic loading conditions.

Main Methods:

• Developed a mechanistic model tracking collagen fiber population dynamics.
• Modeled individual collagen fibers as linear cables with constant stiffness.
• Derived model equations using continuum assumptions and conservation laws.
• Incorporated a linear breaking function to simulate fiber breakage at specific displacements.

Main Results:

• The model demonstrated high accuracy when fitted to experimental data for the cervical anterior longitudinal ligament (R² = 0.995, RMS error = 14.23 N).
• Cyclic loading simulations replicated the force reduction observed in experimental data.
• The model's behavior closely mirrored actual ligament responses during straining to failure.

Conclusions:

• The proposed mechanistic model accurately portrays ligamentous tissue behavior, including failure and cyclic loading.
• This model enhances the realism of biomechanical simulations.
• Future research should refine the breaking function and incorporate viscous effects for improved accuracy.