Evaluation of experimental, analytical, and computational methods to determine long-bone bending stiffness

Area of Science:

• Biomechanics
• Biomaterials Engineering
• Orthopedic Research

Background:

• Evaluating bone mechanical properties is challenging due to inherent complexity and varied methodologies.
• Accurate prediction of bone mechanical properties, specifically flexural rigidity (EI), is crucial for clinical and industrial applications.

Purpose of the Study:

• To quantify the methodological error of common methods used to predict long-bone flexural rigidity (EI).
• To compare the accuracy of experimental, analytical, and computational techniques for EI determination.

Main Methods:

• Utilized a bi-material porcine bone surrogate under four-point bending.
• Employed computed tomography (CT) imaging and digital image correlation (DIC) for data acquisition.
• Compared Euler Bernoulli beam theory, composite modulus calculations, and finite element analysis (FEA) using CAD and CT models.

Main Results:

• Computer-aided design (CAD)-based FEA demonstrated the highest accuracy in predicting bone EI (<5% difference from DIC).
• CT-based FEA showed accuracy for axial strains.
• Analytical calculations overestimated EI, while mechanical testing significantly underestimated flexural rigidity.

Conclusions:

• CAD-based FEA is the most reliable method for determining long-bone flexural rigidity (EI).
• Standard mechanical testing methods may not accurately represent the complex bending stiffness of long bones.