Can finite element models detect clinically inferior cemented hip implants?

Rigorous preclinical testing of cemented hip prostheses against the damage accumulation failure scenario will reduce the incidence of aseptic loosening. For that purpose, a finite element simulation is proposed that predicts damage accumulation in the cement mantle and prosthetic migration. If the simulation is to become a convincing preclinical test, it should be able to distinguish between implants in a clinically relevant way, based on accurate predictions of long-term failure mechanisms of cemented hip prostheses. The algorithm was used to simulate long-term fatigue experiments on femoral reconstructions with Mueller Curved and Lubinus SPII stems. Clinically, the Mueller Curved system performs inferior to the Lubinus SPII system. The finite element simulation predicted much more cement damage around the Mueller Curved stem and showed that the entire cement mantle was involved in the failure process, which was not the case around the Lubinus SPII stem. In addition, the Mueller Curved stem was predicted to migrate more than the Lubinus SPII. The predictions showed excellent agreement with the experimental findings: similar damage locations in the cement, more damage for the Mueller Curved, similar prosthetic migration directions, and more migration for the Mueller Curved stem. This is the first time that a finite element simulation is able to differentiate between a clinically superior and an inferior implant, based on accurate simulation of the long-term failure mechanisms in a cemented reconstruction. Its use for preclinical testing purposes is corroborated