Acrylic antibiotic-loaded bone cement: a basic study

  Abstract   Objective: The aim of this study was to evaluate the efficacy of antibiotic-loaded bone   cement in controlling local infection and in regard to its physical characteristics, elastic   modulus, and tensile strength in-vitro.   Methods: Acrylic bone cement, based on polymethylmethacrylate (PMMA) was   mixed with the powder form of three antibiotics, i.e., gentamicin, tobramycin, and cefuroxime   with different doses below 2gr per 40gr of cement powder thereafter, liquid   monomer was added to process the cement. Sensitivity to common clinical isolates was assessed   by counting the inhibition zone of each ALBC disc in cultured strains. Elution with   normal saline was performed to evaluate the effects on ALBC disks and their antimicrobial   efficiency. Cement structure, tensile strength, and elastic modulus were assessed by biomechanical   tests to understand the characteristics of ALBCs after loading antibiotics with   different doses and two methods of vacuum and manual mixing.   Results: Gentamicin, tobramycin, and cefuroxime reduced bacterial growth significantly   with doses more than 1gr of antibiotics in 40gr of the cement. Cefuroxime was less   efficient than the other two antibiotics in controlling pseudomonas. Elution with normal   saline has not affected antibacterial results, significantly. All the 3 antibiotics had the same   pattern of physical characteristics while loaded in bone cement. Gross structure of ALBCs   with different doses of the three antibiotics was the same as non-ALBC and the elasticity or   strength did not decline after loading antibiotics. The elastic modulus of ALBC was increased   by boosting the doses of antibiotics however, doses of 1gr to 1.5gr were the optimal   doses in this regard. The tensile strength of ALBC was increased by doses of 1gr to   1.5gr of antibiotics however, below and above these doses, the strength was decreased, but   it did not exceed the basic strength of non-ALBC. Vacuum mixing method increased   strength and elasticity more than manual one, remarkably.   Conclusion: Optimal protective effects of ALBCs against infection could be seen with   mixing doses of about 1gr to 1.5gr of antibiotics in 40gr of acrylic bone cements by vacuum   method, while optimal elastic modulus and tensile strength could be achieved at the same   doses.