Porosity of various preparations of acrylic bone cements

The total porosity and mean pore sizes of various bone cement preparations were measured using image analysis. The porosity in different commercial bone cements varied from 5% to 16% when these cements were prepared in the usual fashion. Centrifugation for 30 seconds resulted in a substantial reduction in the overall porosity of Simplex P, AKZ, Zimmer Regular, and CMW bone cements by reducing both the mean pore size and the number of pores per unit area. In contrast, the porosity of LVC, Palacos R, and Palacos R with gentamicin bone cements was not significantly decreased by centrifugation. Chilling the monomer before mixing resulted in higher porosity of both the centrifuged and uncentrifuged Simplex P, Zimmer Regular, and CMW bone cements. Simplex P mixed with chilled monomer and centrifuged for 120 seconds has one of the lowest porosities of the various cements, while retaining good handling characteristics and excellent fatigue strength.