Preventing stress singularities in peri-implant bone - a finite element analysis using a graded bone model

Area of Science:

• Biomechanics
• Finite Element Analysis
• Materials Science

Background:

• Conventional finite element analysis (FEA) models bone as a two-layered material, creating artificial stress singularities at the cortical and cancellous bone interface.
• This simplification leads to inaccurate stress predictions, particularly in the transition zone between bone types.

Purpose of the Study:

• To develop a more realistic FEA model of bone by incorporating the transition zone between cortical and cancellous bone.
• To eliminate stress singularities caused by the conventional two-layered material assumption in FEA of bone.

Main Methods:

• Bone was modeled as a graded material with node-specific Young's modulus values in the FEA simulation.
• The thickness of the transition zone was determined from CT scan data.
• The new graded material model was compared against a conventional two-layered model.

Main Results:

• The graded material model effectively eliminated stress singularities observed in the conventional approach.
• The new approach yielded more accurate predictions of maximum principal stresses within the bone's transition zone.
• The semi-automated modeling process demonstrated a small computational overhead.

Conclusions:

• Modeling bone as a graded material in FEA provides a more accurate representation, avoiding stress singularities.
• This approach enhances the reliability of stress predictions in critical bone regions.
• The automatable nature and minimal overhead make this method suitable for future FEA studies involving bone stress evaluation.