A comparison between dynamic implicit and explicit finite element simulations of the native knee joint

Area of Science:

• Biomechanics
• Computational modeling
• Orthopedics

Background:

• The finite element (FE) method is crucial for studying knee biomechanics.
• Implicit and explicit time integration algorithms are used for dynamic FE analyses.
• A comparative study of these methods is needed for knee modeling.

Purpose of the Study:

• To compare static, dynamic implicit, and dynamic explicit FE solutions for knee joint analysis.
• To assess prediction of dynamic effects, convergence, accuracy, stability, and computational time.
• To evaluate the influence of mass-scaling in explicit FE formulations.

Main Methods:

• Simulated the heel-strike phase of gait (fast, normal, slow) using a native knee FE model.
• Compared static, dynamic implicit, and dynamic explicit time integration algorithms.
• Investigated the impact of two different body masses on simulation outcomes.

Main Results:

• Ignoring dynamic effects in knee biomechanics simulations can alter joint motion predictions.
• Explicit FE analyses are effective for high-speed knee simulations, significantly reducing computational time.
• Explicit methods provide similar predictions of cartilage stresses and meniscus strains compared to implicit methods.
• Mass-scaling in explicit methods offers further computational time reduction but is not suitable for high-speed activities where inertial forces are significant.

Conclusions:

• Explicit time integration algorithms are well-suited for dynamic knee biomechanics simulations, offering computational efficiency.
• Dynamic effects are important to consider in knee joint modeling for accurate motion prediction.
• Careful consideration of mass-scaling is necessary in explicit FE analyses, especially for high-speed dynamic events.