Simple method for increasing drug elution from polymethylmethacrylate bone cement.

OBJECTIVES: This study aims to investigate the effects of the use of citric acid and sodium bicarbonate mixture as an effervescent in polymethylmethacrylate bone cement in terms of better drug elution.

PATIENTS AND METHODS: Multiple cylinder cement blocks each containing 10 g of glucose and different amounts of effervescent (E), with different numbers of pieces (P), surface areas, volumes, and porosities were prepared. Physical properties of all blocks were calculated. Blocks were placed in jars containing saline solutions and the released glucose concentrations were measured at predefined intervals. Correlations between elution rate and physical properties were defined.

RESULTS: Elution rates were significantly higher in samples with effervescent. At the end of 45th day, E0P1 released mean 21% of its glucose content. This value was 38%, 61%, 82% and 88% for E0P2, E0P4, E2P1 and E4P1, respectively. Strong correlations were detected between water absorption ratio, surface areas, porosity and glucose elution rates (r=0.942, p<0.01; r=0.894, p<0.05; r=0.918, p<0.05).

CONCLUSION: Using sodium bicarbonate and citric acid as effervescent in bone cement provides satisfactory porosity development for better antibiotic elution. This method may be useful when a monolithic spacer and better local antibiotic elution are required.