Antibiotic elution from cement: an in vitro study

Background: Prosthetic joint infection is a serious complication of total hip replacement. Cement removal during two stage revisions can be associated with significant morbidity. Exposing new surface area of cement may achieve therapeutic antibiotic elution. Methods: Five blocks containing polymethylmethacrylate (PMMA) and vancomycin were stored in normal saline at 37C and allowed to reach steady state. Different interventions to expose new surface area were performed at six weeks. Results: Post intervention, blocks with the greatest increase in surface area showed the greatest increase in vancomycin levels, the highest increase being 641.77% compared with the control (5.88%). Conclusions: This study confirms antibiotics remain trapped within PMMA after elution ceases. Further release of vancomycin from cement occurs after exposing new surface area. This seems proportional to the exposed surface area size.