Elution, Porosity, and Mechanical Performance of Vancomycin-Loaded Polymethylmethacrylate (PMMA) Bone Cement

Antibiotic-loaded bone cements (ALBCs) are widely used in managing prosthetic joint infection (PJI). This study aimed to compare the antibiotic elution, surface porosity, and mechanical properties of polymethylmethacrylate (PMMA) cement loaded with vancomycin using powdered and liquid incorporation methods.

High-viscosity Palacos R® PMMA was impregnated with 1-4 g vancomycin (powdered or dissolved in water) per 40 g cement. Beads, cylinders, and blocks were fabricated. Antibiotic release was quantified by high-performance liquid chromatography HPLC over 6 weeks. Porosity was assessed by micro-CT whilst compressive and bending strength were measured on an Instron® material testing system.

Powder-mixed beads showed higher cumulative vancomycin release, whilst liquid-mixed beads showed greater porosity than powder-mixed beads. For both powder and liquid-mixed formulations, increasing vancomycin concentration was associated with a dose-dependent reduction in compressive and bending strength compared with control group. Differences between liquid and powder mixed specimens were formulation and loading mode-dependent and were not uniformly directional across concentrations.

Smaller PMMA beads and powder-mixed formulations demonstrated greater early release and higher sustained elution over time, resulting in superior cumulative antibiotic delivery compared with larger beads and liquid-mixed formulations. These findings highlight the need to balance antimicrobial efficacy and mechanical requirements when tailoring formulation of ALBC, particularly in spacer relevant clinical applications.