The changes in stress distribution of femurs with bone ingrown porous-coated hip prosthesis

Several porous-coated femoral components were retrieved postmortem, intact within femurs, for mechanical testing and analysis growth. Axial strains in the proximal femurs were compared to those in cadaver femurs that had been press-fit with similar devices. Press-fit models showed appreciable shielding from compressive strain proximally in comparison with anatomic models; the ingrown joint, in general, exhibited further strain-shielding. Differences noted between the strains seen in the ingrown and press-fit femurs can be attributed to the altered fixation conditions, determined by subsequent analysis of ingrowth into the porous coating. These methods assist in the evaluation of the validity of mechanical testing of porous-coated devices through the implantation of components into cadaver femurs