Simulation of a knee joint replacement during a gait cycle using explicit finite element analysis

Area of Science:

• Biomechanics
• Biomaterials Engineering
• Computational Mechanics

Background:

• Polyethylene insert stress in total knee replacement (TKR) is influenced by complex factors like kinematics and component positioning.
• Previous finite element analyses (FEA) were static, neglecting crucial kinematic influences on stress distribution.
• Accurate simulation of TKR mechanics is vital for understanding wear and improving implant longevity.

Purpose of the Study:

• To develop and validate an explicit finite element (FE) approach for simulating both TKR kinematics and internal polyethylene stresses concurrently.
• To investigate the feasibility of integrating kinematic and stress analysis within a single computational framework.
• To assess the computational efficiency and accuracy of the explicit FE method for TKR simulation.

Main Methods:

• An explicit finite element (FE) model of a total knee joint replacement was developed.
• The model was subjected to a simulated gait cycle within a knee wear simulator.
• Simulated kinematics and internal stresses were compared against experimental data for validation.

Main Results:

• The explicit FE simulation accurately predicted the kinematics of the total knee joint replacement, closely matching experimental data.
• Predicted stresses within the polyethylene insert were found to be dependent on mesh density.
• The simulation demonstrated that kinematic and stress analyses could be effectively combined in a single explicit FE analysis.

Conclusions:

• Explicit finite element analysis is a viable and computationally efficient method for simultaneously predicting TKR kinematics and polyethylene stresses.
• This integrated approach provides a more realistic assessment of implant performance compared to static analyses.
• The findings support the use of explicit FEA for optimizing TKR design and predicting long-term component behavior.