Computational and Experimental Modelling of the Femur

Abstract

In order to advance the design of femoral joints and femoral surgical procedures, it is vital to first understand the way in which the natural femur behaves. This includes the results of how changes at one joint may affect the other, as well as the changes in the femur following total hip replacement, total knee replacement or both. Therefore, the broad aim of this study was to gain a better understanding of the natural femur, through finite element, experiment and beam theory modelling. Fixed boundary condition finite element models of the femur were first constructed highlighting the importance of boundary condition and loading on the strain distribution on the femur. A further-developed free boundary condition model was constructed treating the femur as a complete musculoskeletal construct. Spring elements were used to characterise all muscles and ligaments. From the free boundary condition model, muscle, ligament, joint reaction forces and strain data were extracted. Finally, a sensitivity study was conducted indicating the importance of muscle stiffness relationship selection. Digital image correlation was verified and then used in fixed and free boundary condition experiments. The free boundary condition experiment was used to validate the corresponding finite element model. Finally, a unique beam theory model was developed and compared to the finite element and experimental models. This model is shown to be a useful resource, both for engineers and surgeons, in understanding the way in which the femur acts.