Antibiotic Elution from Bone Cement: A Study of Common Cement-Antibiotic Combinations

The in vitro antibiotic elution characteristics (including the effects of cement fracture) of the following cements were studied: 1) CMW 1 with gentamicin, 2) Palacos R with gentamicin, 3) Palacos LV with gentamicin, 4) CMW 1 with gentamicin and vancomycin, 5) Palacos R with gentamicin and vancomycin, 6) CMW 1 with gentamicin and flucloxacillin, and 7) Palacos R with gentamicin and flucloxacillin. Elution of both gentamicin and vancomycin was satisfactory in all cases. There tended to be a peak of antibiotic release on cement fracture, suggesting sequestration of active antibiotic within deeper layers of the cement. Palacos LV exhibited the best antibiotic elution characteristics but with the highest post-fracture peak. Palacos R was superior to CMW 1. Flucloxacillin was present only until day 4. Adulteration of proprietary Palacos R/gentamicin with flucloxacillin produced prolonged high elution of gentamicin, possibly due to porosity. Flucloxacilloic acid (micro-biologically inactive) was present from day 4 onwards after flucloxacillin was added to cement. These findings suggest that flucloxacillin is not a suitable additive to bone cement in revision surgery.