Experimental attempts to reduce acrylic cement porosity.

In this work, attempts to reduce the levels of porosity in acrylic bone cements were studied. Specimens were cured with additional external pressures or were ejected from commercially available bone cement ejection systems. Density measurements were used to calculate levels of porosity in the specimens. Decreases in porosity were observed when specimens of Zimmer Low Viscosity Cement and Simplex-P bone cements were cured at increased pressures in a stainless steel die. Tensile strengths were increased in those specimens which demonstrated decreases in porosity. Specimens ejected from the cement guns demonstrated significant levels of porosity, but showed improved mechanical properties when ejected from cement guns with narrow orifices. Increased strengths were apparently due to a redistribution of the pores, as was demonstrated by SEM. Continued improvements in mixing and placement of bone cement which would help eliminate porosity are highly recommended.