title: In vitro study of the efficacy of acrylic bone cement loaded with supplementary amounts of gentamicin: effect on mechanical properties, antibiotic release, and biofilm formation.
abstract: BACKGROUND
  Infection remains a severe complication following a total hip replacement. If infection is suspected when revision surgery is being performed, additional gentamicin is often added to the cement on an ad hoc basis in an attempt to reduce the risk of recurrent infection.
  
  
  RESULTS
  In this in vitro study, we determined the effect of incorporating additional gentamicin on the mechanical properties of cement. We also determined the degree of gentamicin release from cement, and also the extent to which biofilms of clinical Staphylococcus spp. isolates form on cement in vitro. When gentamicin was added to unloaded cement (1-4 g), there was a significant reduction in the mechanical performance of the loaded cements compared to unloaded cement. A significant increase in gentamicin release from the cement over 72 h was apparent, with the amount of gentamicin released increasing significantly with each additional 1 g of gentamicin added. When overt infection was modeled, the incorporation of additional gentamicin did result in an initial reduction in bacterial colonization, but this beneficial effect was no longer apparent by 72 h, with the clinical strains forming biofilms on the cements despite the release of high levels of gentamicin.
  
  
  CONCLUSIONS
  Our findings indicate that the addition of large amounts of gentamicin to cement is unlikely to eradicate bacteria present as a result of an overt infection of an existing implant, and could result in failure of the prosthetic joint because of a reduction in mechanical performance of the bone cement.
authors.affiliation: School of Mechanical and Aerospace Engineering, Queen's University, Belfast, UK. n.dunne@qub.ac.uk
authors.forename: Nicholas
authors.initials: N
authors.lastname: Dunne
authors.forename: Janet
authors.initials: J
authors.lastname: Hill
authors.forename: Patricia
authors.initials: P
authors.lastname: McAfee
authors.forename: Katy
authors.initials: K
authors.lastname: Todd
authors.forename: Rachel
authors.initials: R
authors.lastname: Kirkpatrick
authors.forename: Michael
authors.initials: M
authors.lastname: Tunney
authors.forename: Sheila
authors.initials: S
authors.lastname: Patrick
mesh_terms: D000180:Acrylic Resins; D000900:Anti-Bacterial Agents / Q000008:administration & dosage* / Q000493:pharmacokinetics; D001422:Bacterial Adhesion / Q000187:drug effects; D018441:Biofilms / Q000187:drug effects; D001843:Bone Cements; D005839:Gentamicins / Q000008:administration & dosage* / Q000493:pharmacokinetics; D006801:Humans; D011475:Prosthesis Failure; D016459:Prosthesis-Related Infections / Q000382:microbiology* / Q000517:prevention & control; D013210:Staphylococcus / Q000187:drug effects / Q000302:isolation & purification; D013314:Stress, Mechanical; D013997:Time Factors
chemical_list: D000180:Acrylic Resins; D000900:Anti-Bacterial Agents; D001843:Bone Cements; D005839:Gentamicins