Does vacuum-mixing improve the fatigue properties of high-viscosity poly(methyl-methacrylate) (PMMA) bone cement? Comparison between two 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 testing the fatigue properties of bone-cement specimens (Palacos R). Evacuation of the poly(methyl-methacrylate) (PMMA) and evacuation with additional pressurization (Draenert system) were used to manufacture the specimens. Although we found improvement in the ultimate bending strength for evacuated Palacos R, an increase of fatigue stability could not be found either for vacuum-mixed cement or for vacuum-mixed and compressed cement. As fatigue failure is one of the most important factors leading to aseptic loosening of cemented alloarthroplasties, we conclude that the long-term results cannot be improved by vacuum-mixing this cement.