Fatigue failure analysis of a specific total hip prosthesis stem design

In an attempt to achieve initial stability and lack of motion at the cement stem interface, a specific design of the hip prosthesis femoral component was conceived. This design incorporated a specific geometrical feature in the prosthesis stem, namely a screw-like cross section profile. This feature was employed to avoid axial motion as well as stem subsidence into the cement mantle. Based on the numerical simulation results, this investigation reveals that the prosthesis unique design was not responsible for the stem loosening. Once the stem has been loosed, however, the concentration of stress at the geometrical feature root was sufficient to nucleate and propagate a fatigue crack, which eventually culminate in the femoral component catastrophic failure.