title: Bacteria on external fixators: which prep is best?
abstract: BACKGROUND
  There are no established guidelines for the surgical prep of an external fixator in the operative field. This study investigates the effectiveness of different prep solutions and methods of application.
  
  
  METHODS
  Forty external fixator constructs, consisting of a rod, pin, and pin to rod coupling device, were immersed in a broth of Staphylococcus aureus (lux) for 12 hours. Constructs were then randomized into four treatment groups: chlorhexidine-gluconate (CHG) (4%) scrub, CHG (4%) spray, povidone-iodine (PI) (10%) scrub, and PI (10%) spray. Each construct was imaged with a specialized photon capturing camera system yielding the quantitative and spatial distribution of bacteria both before and after the prep. Each pin to bar clamp was loosened and moved 2 cm down the construct, simulating an external fixator adjustment, and reimaged. Spatial distribution of bacteria and total bacteria counts were compared.
  
  
  RESULTS
  There was a similar reduction in bacteria after surgical prep when comparing all four groups independently (p = 0.19), method of application (spray vs. scrub, p = 0.27), and different solutions (CHG vs. PI, p = 0.41). Although bacteria were evident in newly exposed areas after external fixator adjustment, most notably within the loosened pin to bar clamp, it did not result in an increase in bacteria counts (all four groups, p = 0.11; spray vs. scrub, p = 0.18; CHG vs. PI, p = 0.99).
  
  
  CONCLUSIONS
  Although there was no increase in bacteria counts after the simulated external fixator adjustment, it did expose additional bacteria previously unseen. Although there was no difference in surgical prep solution or method of application, consideration must be given to performing an additional surgical prep of the newly exposed surface after loosening of each individual external fixator component as this may further minimize potential bacteria exposure.
authors.affiliation: Department of Regenerative Medicine, United Stated Army Institute of Surgical Research, San Antonio, Texas 78234, USA. daniel.stinner@amedd.army.mil
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Stinner
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Beltran
authors.forename: Brendan D
authors.initials: BD
authors.lastname: Masini
authors.forename: Joseph C
authors.initials: JC
authors.lastname: Wenke
authors.forename: Joseph R
authors.initials: JR
authors.lastname: Hsu
mesh_terms: D000891:Anti-Infective Agents, Local / Q000494:pharmacology*; D015169:Colony Count, Microbial; D004866:Equipment Contamination / Q000517:prevention & control*; D016267:External Fixators / Q000382:microbiology*; D005592:Fracture Fixation / Q000295:instrumentation*; D050723:Fractures, Bone / Q000601:surgery; D006801:Humans; D013203:Staphylococcal Infections / Q000382:microbiology / Q000517:prevention & control*; D013211:Staphylococcus aureus / Q000187:drug effects / Q000302:isolation & purification*; D013530:Surgical Wound Infection / Q000382:microbiology / Q000517:prevention & control*
chemical_list: D000891:Anti-Infective Agents, Local