Differential bacterial load on components of total knee prosthesis in patients with prosthetic joint infection.
OBJECTIVE
The purpose of our study was to evaluate and quantify the bacterial adherence on different components of total knee prosthesis with the sonication culture method.


METHODS
Explanted components of all patients with presumptive prosthetic or implant infection were treated by sonication separately in sterile containers to dislodge the adherent bacteria from the surfaces and cultured. The bacterial load of the different knee components (femur, tibia, PE-inlay and patella) was evaluated by counting of colony-forming units (CFU) dislodged from the components surfaces using the sonication culture method.


RESULTS
Overall, 27 patients had positive sonication cultures of explanted total knee prostheses. Microorganisms were detected from 88 of 100 explanted components. Twenty femoral components were culture positive and 7 negative, 23 tibial components as well as 23 polyethylene (PE) platforms had positive microorganism detection from the surface. Staphylococcus epidermidis adhered to the highest number of components whereas Staphylococcus aureus yielded the highest load of CFU in the sonication cultures. Although not significant, PE-inlays and tibial components were most often affected. The highest CFU count was detected in polyethylene components.


CONCLUSIONS
The sonication culture method is a reliable method to detect bacteria from the components. Additionally, the results demonstrate that bacterial adherence is not affecting a single component of knee prosthesis only. Thus, in septic revision surgery partial prosthetic exchange or exchange of single polyethylene components alone may be not sufficient.
Department of Orthopedic Surgery, Medical University of Vienna, Vienna, Austria. johannes.holinka@meduniwien.ac.at
Johannes
J
Holinka
Magdalena
M
Pilz
Alexander M
AM
Hirschl
Wolfgang
W
Graninger
Reinhard
R
Windhager
Elisabeth
E
Presterl
D001419:Bacteria / Q000145:classification / Q000254:growth & development / Q000302:isolation & purification*; D001422:Bacterial Adhesion; D058491:Bacterial Load; D018441:Biofilms / Q000254:growth & development; D015169:Colony Count, Microbial; D005260:Female; D006801:Humans; D007720:Knee Prosthesis / Q000009:adverse effects* / Q000382:microbiology; D008297:Male; D011095:Polyethylenes; D011474:Prosthesis Design; D016459:Prosthesis-Related Infections / Q000382:microbiology*; D013010:Sonication; D013499:Surface Properties
D011095:Polyethylenes