Post-surgical infections are still one of the most frequent adverse events in the prosthetic surgery. PMMA-based cements are widely employed in orthopaedic surgery as filler or prosthetic fixing device. The main problems associated with this material are poor bone integration and infection development. Aiming to avoid bacterial adhesion and to extend the longevity of implants, different solutions were proposed, both in terms of operative procedures and new materials development. Regarding the materials advancement, innovative PMMA-based composite bone cements, contemporaneously bioactive and antibacterial (without the use of antibiotics), were developed. The composites are based on a PMMA matrix containing a bioactive glass, doped with antibacterial ions (Ag+ or Cu++); so, the same filler shows at the same time the ability of promoting bone ingrowth and an antibacterial effect. Composite cements were characterized in terms of morphology and composition, curing parameters and mechanical properties; in vitro tests were performed to verify the material ability to release antibacterial ions and to promote the precipitation of hydroxyapatite. Moreover, cytotoxicity and antimicrobial properties were verified. The cements characteristics were tested using different commercial matrix and different viscosities; therefore, the proposed formulations represent an innovative solution for a new family of antibiotic-free, bioactive and antibacterial cements.

Summary Statement

The problem facing this research is to promote rapid osteointegration of titanium implants and to minimise the risks of infections by the functionalization with different agents, each designed for a specific action. A patented process gives a multifunctional titanium surface.

Aims: A serious problem in orthopedic surgery is the development of infections. The realization of antibacterial and biocompatible/bioactive surfaces represents a challenge. In this study antibacterial behavior has been conferred to surfaces of glasses and glass-caramics, with different degrees of bioactivity, by the introduction of silver through ion exchange.

Methods: Materials have been studied both in bulk form, and as coatings. All samples have been analyzed by means of XRD, SEM and EDS before and after the treatment. Coatings’ roughness, porosity and adhesion resistance have been also analyzed. In vitro reactivity and silver release were carried out soaking samples in SBF. Samples have been analyzed by means of SEM/ EDS and XRD; silver has been quantified in solution by GFAAS. Cellular tests have been performed in order to evaluate materials biocompatibility before and after the treatment. Antibacterial behavior has been tested against S.Aureus.

Results: Characterization analyses show that glassy or crystalline structure and morphology are maintained after the ion-exchange. As well the coating adhesion resistance is higher then the limit provided by ISO standard for hydroxyapatite coatings. GFAAS analysis determined that silver is gradually released in solution. Cellular tests demonstrate that biocompatibility is generally maintained after treatment but it is closely connected to the amount of silver released. Microbiological tests show antibacterial behavior for silver-doped samples.

Conclusions: Ion-exchange technique permits the introduction of controlled silver amount without modifying materials’ structural and morphological properties. Comparing cellular and microbiological tests it is possible to design process parameters to confer, antibacterial properties but not cytotoxic behavior.