title: A novel knee prosthesis model of implant-related osteomyelitis in rats.
abstract: OBJECTIVE
  There have been numerous reports of animal models of osteomyelitis. Very few of these have been prosthesis models that imitate human conditions. We have developed a new rat model of implant-related osteomyelitis that mimics human osteomyelitis, to investigate the pathology of infection after orthopedic implant surgery.
  
  
  METHODS
  2 wild-type strains of Staphylococcus aureus, MN8 and UAMS-1, and their corresponding mutants that are unable to produce poly-N-acetyl glucosamine (PNAG) (ica::tet) were injected into the medullary canals of the femur and tibia at 3 different doses: 10(2), 10(3), and > 10(4) CFU/rat. We measured clinical signs, inflammatory markers, radiographic signs, histopathology, and bacteriology in the infected animals.
  
  
  RESULTS
  An inoculum of at least 10(4) cfu of either wild-type bacterial strain resulted in histological, bacteriological, and radiographic signs of osteomyelitis with loosening of the prosthesis. An inoculum of 10(3) CFU gave signs of osteomyelitis but the prosthesis remained in situ. Bacterial inocula of 10(2) cfu gave no signs of osteolysis.
  
  
  CONCLUSIONS
  We have established a new knee prosthesis model that is suitable for reliable induction of experimental implant-associated osteomyelitis with the prosthesis in situ, using a small inoculum of S. aureus. At a dose of 10(3) CFU/rat, bacteria unable to produce PNAG (ica::tet) had only minor defects in their virulence.
authors: Hand Section, Department of Planned Surgery Z, Gentofte University Hospital, Denmark. nsn@dadlnet.dk
authors: Niels H
authors: NH
authors: Søe
authors: Nina Vendel
authors: NV
authors: Jensen
authors: Birgit Meinecke
authors: BM
authors: Nürnberg
authors: Asger Lundorff
authors: AL
authors: Jensen
authors: Janne
authors: J
authors: Koch
authors: Steen Seier
authors: SS
authors: Poulsen
authors: Gerald
authors: G
authors: Pier
authors: Helle Krogh
authors: HK
authors: Johansen
mesh_terms: D000818:Animals; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects* / Q000295:instrumentation / Q000379:methods; D004195:Disease Models, Animal; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging / Q000382:microbiology / Q000473:pathology; D008297:Male; D010019:Osteomyelitis / Q000000981:diagnostic imaging / Q000209:etiology* / Q000382:microbiology / Q000473:pathology; D016459:Prosthesis-Related Infections / Q000000981:diagnostic imaging / Q000209:etiology* / Q000382:microbiology / Q000473:pathology; D011859:Radiography; D051381:Rats; D017207:Rats, Sprague-Dawley; D013203:Staphylococcal Infections / Q000209:etiology / Q000382:microbiology