In Vitro Study on the Degradation Behavior of Different Antibiotic-Loaded Biomaterials for Orthopedic Applications

Local antibiotic delivery systems are increasingly used in orthopedic surgery to achieve optimal drug concentrations at the site of infection while minimizing systemic side effects. Among these systems, calcium sulfate-based resorbable cements and polymethyl methacrylate-based acrylic cements are commonly used. In this study, the structure, surface properties, and in vitro degradation behavior of CaSO4-based samples loaded with gentamicin, vancomycin, or a combination thereof were investigated and compared with those of a calcium sulfate control sample and polymethyl methacrylate-based acrylic cement. The characterization of the materials was performed using Fourier Transform Infrared Spectroscopy and Scanning Electron Microscopy coupled with Energy Dispersive X-ray Spectroscopy. Surface wettability was assessed using contact angle measurements, and immersion tests were used to evaluate water absorption and mass loss. The results showed that the introduction of antibiotics into CaSO4-based samples affected surface wettability, microstructure, and degradation profiles, particularly in samples containing gentamicin. A different behavior was observed in the case of acrylic cement, for which the mass loss is mainly attributed to the release of soluble components from the composition, such as residual monomer and antibiotics. Compared with acrylic cement, calcium sulfate-based samples, particularly those loaded with gentamicin, exhibited more hydrophilic surfaces and a microstructure that favors interaction with aqueous media, thereby leading to superior performance as local antibiotic delivery systems.