The quality of trabecular bone evaluated with micro-computed tomography, FEA and mechanical testing

Area of Science:

• Biomedical Engineering
• Orthopedics
• Materials Science

Background:

• Standard bone quality prediction relies on apparent density, which inadequately captures mechanical properties and structural anisotropy.
• Apparent density alone may not sufficiently predict bone quality due to limitations in explaining mechanical variations.

Purpose of the Study:

• To investigate the utility of microstructural computer models for enhanced bone quality assessment.
• To determine if advanced computational methods provide additional relevant information beyond apparent density measurements.

Main Methods:

• Utilized 3-D micro-Computed Tomography (micro-CT) to image 58 human trabecular bone samples from the femoral head at 28-micron resolution.
• Applied microstructural Finite Element Analysis (FEA) to compute orthotropic stiffness matrices and principal directions from micro-CT data.
• Validated elastic moduli with tri-axial mechanical compression tests on a subset of six samples.

Main Results:

• Bone volume fraction explained only a portion of the variation in elastic properties, with up to 15% unexplained.
• Significant differences in elastic properties (up to 53%) were observed between samples with similar bone volume fractions.
• Direction-dependent stiffness varied by a factor of four, highlighting the limitations of isotropic predictions from apparent density.

Conclusions:

• Micro-CT-based FEA provides direct, non-destructive insights into bone anisotropy and mechanical properties.
• This advanced approach offers crucial information for improved bone failure risk prediction.
• Future applications may involve integrating these methods with high-resolution CT or MRI for clinical patient examinations.