Medical vs MicroCT based Finite Element Analysis : Exploring the Influence of Bone Heterogeneity and Bone Geometry

Area of Science:

• Biomechanics
• Medical Imaging
• Finite Element Analysis (FEA)

Background:

• Accurate finite element analysis (FEA) of uncemented prostheses relies on precise bone geometry and density from CT scans.
• Direct comparisons of medical CT and micro-CT (μCT) for FEA, considering bone heterogeneity and geometry, are limited.
• Understanding these differences is crucial for reliable mechanical evaluation of bone-implant interfaces.

Purpose of the Study:

• To directly compare medical-CT and μCT-based FEA in evaluating uncemented prostheses.
• To demonstrate the impact of bone heterogeneity and geometry on FEA outcomes.
• To assess the influence of different material models and CT scan technologies on FEA results.

Main Methods:

• Compared three material models and two CT scan technologies (medical-CT and μCT).
• Evaluated FEA models at a specific region of interest (ROI) under identical loading conditions.
• Analyzed the effects of bone heterogeneity versus homogeneous material models.

Main Results:

• Bone heterogeneity reduced material stiffness by 20.57% (μCT) and 24.07% (medical-CT), decreasing stress concentration.
• While peak stresses were similar, stress contours and peak locations differed between medical-CT and μCT FE models due to geometry and heterogeneity variations.
• Discrepancies in FEA can lead to incorrect load transfer indications for uncemented prostheses.

Conclusions:

• Bone geometry and heterogeneity significantly influence FEA results for uncemented prostheses.
• Differences between medical-CT and μCT scans can alter stress distribution and peak stress locations.
• Careful selection of material models and bone geometry is essential, especially when trabecular mechanics are critical.