Finite Element Analysis for the Load-Bearing Femur and Tibia in the Human Knee Using an in vivo HR-pQCT Protocol

Area of Science:

• Biomechanics
• Medical Imaging
• Computational Modeling

Background:

• High-resolution peripheral quantitative CT (HR-pQCT) and micro-finite element (μFE) analysis offer noninvasive bone mechanics assessment.
• Knee μFE modeling presents challenges due to complex geometry and boundary condition requirements.
• Standardization is crucial for reproducible mechanical predictions in knee μFE analysis.

Purpose of the Study:

• To develop and validate standardized HR-pQCT-based μFE knee modeling.
• To assess the influence of support layer parameters on mechanical predictions.
• To evaluate the reproducibility of knee μFE models.

Main Methods:

• Patient-specific μFE models were created using HR-pQCT data from healthy volunteers and an ACL-injured participant.
• Simulated-PMMA support layers with varying stiffness, geometry, and extrusion lengths were incorporated.
• Sensitivity analyses and reproducibility assessments (RMS%CV, ICC) were performed on tibial scans.

Main Results:

• Support layer stiffness significantly impacted tibial strain energy density (SED); geometry and length had minimal effects.
• μFE knee models required substantial computational resources (3.6-20.1h).
• Tibial scan reproducibility showed good to excellent reliability (ICCs 0.72-0.94), with specific regions demonstrating higher stability.

Conclusions:

• Standardized HR-pQCT-based μFE knee modeling is essential for reproducible bone mechanics assessment.
• An anatomically shaped support layer (~2500MPa stiffness, 3mm extrusion) offers computational efficiency and stable load distribution.
• This standardized approach will enhance comparability in future longitudinal knee studies.