DOES VACUUM-MIXING IMPROVE THE FATIGUE PROPERTIES OF HIGH-VISCOSITY POLY(METHYLMETHACRYLATE) (PMMA) BONE-CEMENT - COMPARISON BETWEEN 2 DIFFERENT EVACUATION METHODS

The objective was to verify different reports in the literature which show an increase of stability using vacuum-mixing of bone cement, by t esting the fatigue properties of bone-cement specimens (Palaces R). Ev acuation of the poly(methyl-methacrylate) (PMMA) and evacuation with a dditional pressurization (Draenert system) were used to manufacture th e specimens. Although we found improvement in the ultimate bending str ength for evacuated Palaces R, an increase of fatigue stability could not be found either for vaccum-mixed cement or for vacuum-mixed and co mpressed cement. As fatigue failure is one of the most important facto rs leading to aseptic loosening of cemented alloarthroplasties, we con clude that the long-term results cannot be improved by vaccum-mixing t his cement.