Computer aided stress analysis of the femur with prosthetic hip stem utilizing computed tomography

A computer aided analysis method utilizing computed tomography (CT) together with a finite element program to determine the stress patterns in a femur with a total hip prosthesis is discussed. The CT scan data file provide the geometry for the three-dimensional finite element model. The model of femur-prosthesis is automatically generated from the CT data file by a preprocessing procedure which includes an edge detection algorithm to determine the boundaries of the reconstructed cross sectional images of the scanned bone. Formatted input data for ANSYS finite element program is generated by the preprocessor to calculate the stresses and displacements at the nodes and elements of the model. A practical method to transfer the CT data to the CAD/CAM system creating a three-dimensional bone geometry is developed. The edge data generated by the preprocessor are also introduced into a solid modeling package to produce a three-dimensional plastic solid model