Magnetic Resonance Imaging-Based Cohesive Extended Finite Element Modeling of Atypical Femoral Fracture

Area of Science:

• Biomedical Engineering
• Orthopedic Research
• Medical Imaging

Background:

• Atypical femoral fractures (AFFs) are rare but serious complications associated with prolonged bisphosphonate (BP) therapy.
• Both femoral geometry and altered bone material properties are implicated in AFF development.
• Current assessment methods may not fully capture the complex factors contributing to AFF.

Purpose of the Study:

• To introduce and validate a novel approach integrating high-resolution magnetic resonance imaging (MRI) with cohesive extended finite element method (XFEM) for AFF assessment.
• To quantify the independent contributions of femoral geometry and material properties to fracture resistance at the AFF site.
• To establish a foundation for MRI-based AFF risk assessment.

Main Methods:

• Development of MRI-based finite element models of female femurs.
• Incorporation of specimen-specific heterogeneous material properties derived from MRI-based bone volume fraction (BVF).
• Validation through experimental testing of femurs under simulated stance loading.

Main Results:

• Geometrical factors like anterior bowing and neck shaft angles showed correlations with fracture load.
• Increased bone volume fraction (BVF) correlated positively with fracture load.
• Simulated femoral stiffness and lateral strains at the AFF site significantly correlated with experimental data.

Conclusions:

• MRI-based cohesive XFEM is a viable method for assessing crack formation in atypical femoral fractures.
• Both geometrical and material properties of the femur are crucial for accurate AFF risk assessment.
• This integrated imaging and modeling approach offers potential for advanced, MRI-specific fracture risk evaluation.