Abstract
Geometric and material changes in the femoral neck following hip resurfacing have been linked to femoral neck fractures.
This study developed a unique method to determine the level of influence of the implant stem on the structural changes in the femoral neck following surgery.
A 3D femur model was generated using CT-images. The finite-element model was meshed using 10-noded tetrahedral elements. An ASR hip-resurfacing component (Depuy International, Leeds) was implanted into the femur in load sensitive position. A strain-adaptive bone-remodelling algorithm was used to determine the bone-remodelling behaviour of the femur over a minimum of 2-year period.
Following the analysis, the material properties and stresses in the neck region were mapped onto a cubic mesh, which simulated a CT stack. Moments of inertia, bending moments and shear was calculated for each slice along the neck of femur. These were compared to the pre-operative model.
Bone mineral density changes in the neck region were observed following implantation due to the changes in moments of inertia, bending moments and shear loading.
A method to determine the effect of implantation on the geometric and densitychanges in the femoral neck following resurfacing was developed. This methodology has shown that implant stem geometry affects the load transfer to the femur and the adaptive behaviour of the femoral neck. This will influence the structural integrity of the femoral neck and the long-term clinical outcome of the hip resurfacing component.
The abstracts were prepared by David AF Morgan. Correspondence should be addressed to him at davidafmorgan@aoa.org.au
Declaration of interest: a
