Mechanical failure of the femoral component in cemented total hip replacement--a finite element evaluation.

The quality of cementation is of paramount importance for the long-term clinical outcome in cemented total hip replacement. Four "modes of failure" have been differentiated by various authors and correlated with the clinical findings. A finite element analysis was performed to simulate an ideally cemented femoral stem-type prosthesis as well as failure modes III (proximal anchorage of implant only) and IV (Distal anchorage of implant only). While failure mode III produces a stress distribution at the bone/acrylic cement interface, which is similar to the ideally cemented prosthesis, failure mode type IV leads to a hazardous rise of the interface stresses. This correlates well with the clinical findings given in the literature, thus validating the computer simulation used. Distal cementation only of a stem-type femoral component in total hip replacement should definitely be avoided.