Effects of mixing techniques on vancomycin-impregnated polymethylmethacrylate.

The use of antibiotic-impregnated polymethylmethacrylate in joint arthroplasty is widespread. The Food and Drug Administration has approved commercially prepared antibiotic bone cement, but in a climate of increasingly drug-resistant bacteria, orthopedic surgeons often hand-mix their own. A recent study reported the effects on drug elution of different mixing methods designed to decrease antibiotic particle size and distribute those particles more uniformly. Theoretically, these mixing techniques could also improve antibiotic cement strength; however, the actual effects of these techniques on cement strength are undefined. In the present study, 3 different methods of mixing vancomycin with bone cement were compared. We conclude that the addition of vancomycin to polymethylmethacrylate at commonly accepted concentrations does substantially decrease cement strength and that more complex mixing techniques do not improve cement strength significantly.