Investigation of Mechanical Properties of PMMA Cement Impregnated with Ciprofloxacin and Vancomycin

In the present study, effects of adding ciprofloxacin and vancomycin on the compression and bending properties of PMMA bone cement have been investigated. The strength and modulus of cement containing different concentrations of antibiotics (0, 2.5, 5 and 10% W/W) has been determined. The samples were incubated at 37 ℃ for 4 weeks and the studies were performed weekly at room temperature. Both ciprofloxacin and vancomycin significantly decreased the mean strength values in comparison to control group (ANOVA, p 0.05). This reduction was due to increased porosity upon antibiotic addition (3.05 and 3.67% for ciprofloxacin and vancomycin, respectively) in comparison to control (2.08%) (ANOVA, p 0.001). The maximum reduction of cement strength and modulus was observed after two weeks. Late polymerization phenomena resulted in increase of cement mechanical properties over time. When the effects of two antibiotics compared, there were significant differences at 10% group on day 14 in both compression and bending tests (ANOVA, p 0.01), but for lower concentrations, no significance difference was observed. In conclusion, the antibiotic loading affect mechanical properties of the bone cement and these effects are both drug content and time dependent.