en Orthopedic Surgery Orthopedic Surgery Original Research Original Research <p><strong>  Abstract</strong> </p><p><strong>  Objective:</strong> The aim of this study was to evaluate the efficacy of antibiotic-loaded bone </p><p>  cement in controlling local infection and in regard to its physical characteristics, elastic </p><p>  modulus, and tensile strength in-vitro. </p><p>  <strong>Methods:</strong> Acrylic bone cement, based on polymethylmethacrylate (PMMA) was </p><p>  mixed with the powder form of three antibiotics, i.e., gentamicin, tobramycin, and cefuroxime </p><p>  with different doses below 2gr per 40gr of cement powder thereafter, liquid </p><p>  monomer was added to process the cement. Sensitivity to common clinical isolates was assessed </p><p>  by counting the inhibition zone of each ALBC disc in cultured strains. Elution with </p><p>  normal saline was performed to evaluate the effects on ALBC disks and their antimicrobial </p><p>  efficiency. Cement structure, tensile strength, and elastic modulus were assessed by biomechanical </p><p>  tests to understand the characteristics of ALBCs after loading antibiotics with </p><p>  different doses and two methods of vacuum and manual mixing. </p><p><strong>  Results:</strong> Gentamicin, tobramycin, and cefuroxime reduced bacterial growth significantly </p><p>  with doses more than 1gr of antibiotics in 40gr of the cement. Cefuroxime was less </p><p>  efficient than the other two antibiotics in controlling pseudomonas. Elution with normal </p><p>  saline has not affected antibacterial results, significantly. All the 3 antibiotics had the same </p><p>  pattern of physical characteristics while loaded in bone cement. Gross structure of ALBCs </p><p>  with different doses of the three antibiotics was the same as non-ALBC and the elasticity or </p><p>  strength did not decline after loading antibiotics. The elastic modulus of ALBC was increased </p><p>  by boosting the doses of antibiotics however, doses of 1gr to 1.5gr were the optimal </p><p>  doses in this regard. The tensile strength of ALBC was increased by doses of 1gr to </p><p>  1.5gr of antibiotics however, below and above these doses, the strength was decreased, but </p><p>  it did not exceed the basic strength of non-ALBC. Vacuum mixing method increased </p><p>  strength and elasticity more than manual one, remarkably. </p><p>  <strong>Conclusion:</strong> Optimal protective effects of ALBCs against infection could be seen with </p><p>  mixing doses of about 1gr to 1.5gr of antibiotics in 40gr of acrylic bone cements by vacuum </p><p>  method, while optimal elastic modulus and tensile strength could be achieved at the same </p><p>  doses. </p><p>  </p> ALBC, acrylic bone cement, antibiotic, microbiology, biomechanics 125 131 http://mjiri.iums.ac.ir/browse.php?a_code=A-10-1-3&slc_lang=en&sid=1 Hossein Farahini 20031947532846001636 20031947532846001636 No Orthopedic Surgeon and Fellowship of Knee and Arthroscopy, Rasool Akram Mehdi Ghorbani 20031947532846001637 20031947532846001637 No Rasool Akram General Hospital. Ehsan Akbarian eakbarian@gmail.com. 20031947532846001638 20031947532846001638 Yes Shahid Beheshti University of Medical Sciences.