Linear poroelastic cancellous bone anisotropy: trabecular solid elastic and fluid transport properties

Area of Science:

• Biomechanical Engineering
• Materials Science
• Bone Physiology

Background:

• Cancellous bone's mechanical function relies on fluid-solid interactions.
• Understanding trabecular bone's biphasic performance is key to its mechanical role.
• Anisotropic organization of bone's solid and pore volumes influences its properties.

Purpose of the Study:

• To separately characterize the anisotropic mechanical performance of cancellous bone's solid and pore volumes.
• To investigate the relationship between fluid flow (permeability) and solid mechanics (elastic moduli) in trabecular bone.
• To define the biphasic nature of cancellous bone tissue and its implications for mechanical function.

Main Methods:

• Applied linear poroelasticity theory to experimental data.
• Used ultrasonic wave propagation to determine orthotropic elastic moduli and material stiffness coefficients.
• Analyzed fluid flow via orthotropic permeability and established an empirical relationship between permeability and porosity.

Main Results:

• Mean parameters in the superior-inferior (SI) orientation were significantly larger than medial-lateral (ML) and anterior-posterior (AP) orientations.
• Apparent elastic modulus, permeability, and material stiffness coefficient were highest in the SI direction.
• A negative correlation between permeability and structural elastic modulus was observed across all orientations.

Conclusions:

• Cancellous bone exhibits anisotropic mechanical properties influenced by its structural organization.
• Fluid transport and solid elasticity are interrelated in trabecular bone's mechanical response.
• The findings provide insight into trabecular connectivity and biphasic performance under loading.