Enhanced drug delivery of antibiotic-loaded acrylic bone cements using calcium phosphate spheres

Background: Local infection near an implant may pose a serious problem for patients. Antibiotic delivery from acrylic (poly(methyl methacrylate)-based) cements is commonly used to prevent and treat infections in the proximity of, e.g., hip joint implants. However, at present, the drug release properties of PMMA cements are not optimal. An initial burst followed by very slow release means that an unnecessarily large amount of antibiotic needs to be added to the cement, increasing the risk of bacterial resistance. The main purpose of this study was to enhance drug delivery from PMMA cements without influencing the mechanical properties. Methods: We incorporated strontium-doped calcium phosphate spheres (SCPS) into PMMA cement to enhance the antibiotic release and potentially improve the bone-cement integration. The release of strontium and vancomycin was investigated using inductively coupled plasma atomic emission spectroscopy and UV spectrophotometry, respectively. Results: It was found that incorporating SCPS into PMMA could enhance the antibiotic release and deliver strontium ions to the surroundings. The incorporation of SCPS also increased the radiopacity as well as the working time of the cement. The compressive strength and Young's modulus were not affected. Conclusions: Our results showed that SCPS/PMMA antibiotic-loaded cement had enhanced antibiotic release, delivered strontium ions and maintained mechanical properties, indicating that the SCPS additive could be a good alternative for controlling the drug-delivery properties of PMMA cement.