A radiopaque calcium phosphate bone cement with long-lasting antibacterial effect: From paste to injectable formulation

The development of infections still represents a severe problem in orthopedic field. In this work, we developed an anti-microbial and radiopaque calcium phosphate bone cement with a long-lasting inhibitory activity thanks to the addition of gentamicin sulphate-loaded solid lipid microparticles obtained by spray congealing. Cements containing gentamicin both added into cement powder and loaded into microparticles were prepared and characterized and their properties were compared. The results of structural, morphological, mechanical and in vitro characterizations indicate that inclusion of gentamicin into microparticles is a good approach in order to obtain materials able to display a strong inhibition towards the growth of Gram-negative, as well as Gram-positive bacteria and to enhance the viability of osteoblast-like cells. All the compositions have an excellent activity also against clinical isolates, including multi drug resistant phenotypes. In particular, cements containing gentamicin-loaded microparticles display a strong and long-term inhibitory activity. Suitable modification of the liquid/powder ratio provided injectable formulation, whereas addition of BaSO4 produced radiopacity. All the formulations display good injectability and cohesion, and no evidence of demixing.