Combining specimen-specific finite-element models and optimization in cortical-bone material characterization...

Area of Science:

• Biomechanics
• Materials Science
• Orthopedic Research

Background:

• Three-point bending tests are common for deriving bone material properties.
• Traditional beam theory has limitations in accurately predicting post-yield biomechanical behavior.

Purpose of the Study:

• To develop and validate a finite element (FE) based optimization method for accurate bone material parameter derivation.
• To compare the accuracy of FE-based optimization with traditional beam theory in three-point bending tests.

Main Methods:

• Tested 80 machined bovine cortical bone specimens in longitudinal and transverse directions using three-point bending.
• Derived material parameters using both beam theory and a specimen-specific FE-based optimization method.
• Validated derived parameters by comparing FE simulations with experimental force-displacement data.

Main Results:

• FE models using material properties from FE-based optimization showed superior agreement with experimental data, including the post-yield region.
• Beam theory with strain offset yielded results closer to FE-based optimization than without strain offset.
• The FE-based optimization method demonstrated higher accuracy in predicting bone biomechanical properties.

Conclusions:

• FE-based optimization is more appropriate than beam theory for identifying cortical bone material parameters in three-point bending.
• The proposed method enhances prediction accuracy, particularly for post-yield behavior.
• Correction functions are provided to improve the accuracy of beam theory parameters for FE simulations.