3D-Printed Antibiotic Beads with Controlled Microarchitectures for Customizable Elution Profiles: An In Vitro Study.

Introduction: Polymethylmethacrylate (PMMA) antibiotic beads are widely used in orthopedic surgery for localized infection control, but inconsistent drug elution can limit efficacy. Three-dimensional (3D) printing offers a way to create implants with controlled architectures, enabling more predictable and customizable drug release. This study explores the use of internal structural variation to influence the elution profiles of vancomycin and tetracycline and assess their antibacterial properties. Methods: Cylindrical specimens were 3D printed using a commercial resin mixed with 2% vancomycin or tetracycline. To evaluate the effects of composition and structure, additives such as sodium chloride (NaCl) and polyvinylpyrrolidone (PVP) were included, and four internal architectures-solid, hollow, large honeycomb, and small honeycomb-were tested. Elution was assessed over 7 days, and antibacterial activity was tested against Results: Tetracycline exhibited greater cumulative release than vancomycin, likely due to solubility and molecular weight differences. Honeycomb structures, especially the smaller variant, produced the most sustained and consistent elution profiles. NaCl decreased vancomycin but increased tetracycline release, while PVP enhanced release for both. All formulations showed antibacterial efficacy. Discussion: 3D printing enables the design of antibiotic-eluting implants with tailored release profiles. The honeycomb architecture is especially promising for sustained delivery. Further in vivo studies are needed to confirm clinical relevance and optimize formulations for orthopedic use.