A finite element model for evaluation of tibial prosthesis-bone interface in total knee replacement

Area of Science:

• Biomechanics
• Biomaterials Engineering
• Orthopedic Surgery

Background:

• Total knee replacement (TKR) relies on effective load transfer between the tibial implant and bone.
• Understanding bone-implant interface mechanics is crucial for TKR longevity and success.
• Existing models often simplify bone properties and interface behavior.

Purpose of the Study:

• To develop and validate a numerical model for analyzing load transfer at tibial bone-implant interfaces in TKR.
• To investigate the influence of bone anisotropy and interface discontinuity on stress distribution and micromotion.
• To compare the mechanical behavior of different tibial implant designs (MTTC and PCA).

Main Methods:

• Finite element method (FEM) for numerical modeling.
• Transverse isotropic material model for bone constitutive laws.
• Coulomb's friction criterion for interface modeling.
• Analysis of stress distributions and micromotions under various loading conditions.

Main Results:

• The model accurately predicted stress and micromotion distributions at bone-implant interfaces.
• Porous Coated Anatomic (PCA) plateaus exhibited greater deformability and displacement than Metal Tray Total Condylar (MTTC).
• Uncemented PCA showed bone-peg interface debonding, with lower stress peaks beneath the tray compared to MTTC.
• Bone anisotropy and interface discontinuity significantly influenced the model's results.

Conclusions:

• The developed FEM model provides valuable insights into load transfer mechanisms in TKR.
• Tibial implant design and interface characteristics critically affect mechanical outcomes.
• Bone anisotropy and interface discontinuity are essential factors to consider in TKR design and analysis.