Anisotropic bone remodelling model based on a continuum damage-repair theory.

Area of Science:

• Biomechanics
• Materials Science
• Computational Modeling

Background:

• Bone remodeling is a complex biological process essential for maintaining skeletal integrity.
• Existing models often lack the ability to fully capture the microstructural evolution and anisotropic properties of bone.

Purpose of the Study:

• To present a novel computational model for internal bone remodeling.
• To formulate bone microstructure evolution using Continuum Damage Mechanics (CDM) principles.
• To introduce a remodeling tensor that characterizes homogenized bone microstructure and stiffness.

Main Methods:

• Development of a remodeling tensor based on apparent density and fabric tensor.
• Definition of mechanical stimulus thermodynamically associated with the remodeling tensor.
• Formulation of resorption and apposition criteria and an evolution law for the remodeling tensor.
• Application of the model to the proximal femur to validate against experimental data.

Main Results:

• The proposed remodeling tensor accurately describes bone microstructure state and stiffness.
• The model allows for negative variation of the remodeling tensor, enabling 'repair' mechanisms.
• Key experimental features, such as the alignment of fabric and elasticity tensors with stress, are naturally deduced.
• Simulations of proximal femur remodeling closely matched experimental observations.

Conclusions:

• The new CDM-based model provides a robust framework for understanding internal bone remodeling.
• The model successfully integrates microstructural changes with macroscopic mechanical properties.
• This approach offers a powerful tool for investigating skeletal diseases and developing therapeutic strategies.