Medical Journal of The Islamic Republic of Iran (MJIRI)

  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.