Antimicrobial potential of bioactive bone cements

Poly(methyl methacrylate) (PMMA) based bone cement is widely used to anchor artificial joints. In recent years, antibiotics have been incorporated in bone cements and administered systemically to either prevent or reduce the severity of infections. Certain antibiotics, such as tobramycin or vancomycin antibiotics have been incorporated at high concentrations into PMMA bone cements when dealing with infected hip joints, however, the inclusion of some antibiotics adversely affect the mechanical properties of the cement. Furthermore, studies have indicated that the incorporation of gentamicin in PMMA cements does not have a statistically significant effect on the biofilm formation of species such as Staphylococcus aureus (S. aureus). Bioactive glasses have been shown to have numerous applications in the biomedical field because of their properties in bonding to both hard and soft tissues. Bioglass undergoes surface dissolution in a physiological environment forming a hydroxycarbonate apatite layer and, in addition, exhibits the anti-inflammatory properties. Recent studies have shown that two paste bioactive bone cement systems that use Bioglass as filler exhibit physical and mechanical properties comparable to PMMA cements with low polymerization exotherm and better mechanical properties with improved adhesion to bone and implant surfaces. In this study, Bioglass containing two paste bone cements were investigated for their potential bacteriostatic properties and compared with PMMA cements with and without antibiotics. The results of this study indicated that the PMMA cement containing the antibiotic, gentamycin and the Bioglass containing cements both pre- and post-immersion in simulated body fluid (SBF) for brief periods showed the inhibition zones were not statistically significantly different in their average size for any of the three bacterial species, namely Pseudomonas aeruginosa, S. aureus and Staphylococcus epidermidis. However, the PMMA cement without any antibiotic, namely gentamycin (CMW1) did not show any inhibition zones around the specimens for any of the three bacterial species. It was also noted that both Bioglass filled bioactive cements immersed in SBF showed statistically significant increases in inhibition zones for all three specimens compared to specimens that were not immersed (p