Finite Element Nonlinear Dynamic Response Analysis of the Human Knee Joint

Objective. To develop a detailed non-linear 3-D dynamic finite element model of the knee joint and perform preliminary analysis simulating different loading conditions to confirm reasonable function of the model.

Design. Using ANSYS, a finite element model of the human knee was created and tested.

Background. Finite element models of the knee have been developed in previous studies. However, no study has generated a detailed tissue level model, or performed dynamic testing on a model.

Methods. Initial cartilage and ligament geometry was received from a previous study. A finite element mesh including bone was created. The model was constrained to simulate different experimental testing conditions by rigidly fixing the distal tibia and limiting the motion of the proximal femur. Free vibration and steady state analyses of the model were performed simulating experiments.

Results. A detailed, highly nonlinear finite element model of the human knee was created in three dimensions. Axial compressive load and two constraint conditions were applied. Solution was performed to the point of easy convergence. The model was also examined through dynamic analysis to find the mode shapes. The model performed well under this initial analysis.

Conclusion. The model was developed and tested successfully. The model needs further refinement and verification with experimental data to follow. The preliminary analysis of the model indicated that constraint conditions could significantly affect the magnitude and distribution of stresses within the different components of the knee joint. Mode shapes are also varied at different constraint conditions. The model is applicable to predict the vulnerable parts of the knee joint at different clinical situations as well as occupational conditions.