[Orthopaedic implant-associated infections: Update of antimicrobial therapy]

In infections related to prosthetic joints and internal fixation devices, microorganisms adhere as biofim on the surface of the implant. Biofilms are not only resistant to phagocytosis, but also to most antimicrobial agents. Therefore, spontaneous cure does never occur, and antibiotics have to be given for several months. According to traditional concepts, removal of all foreign material was considered as prerequisite for cure. Yet, during the last decades, it has been shown that staphylococcal biofilms can be eliminated by rifampin combination therapy, and Gram-negative biofilms by fluoroquinolones. However, reliable biofilm elimination is only possible, if the duration of infection does not exceed 3-4 weeks. Correct total duration of the antimicrobial therapy has never been tested in a controlled trial. Currently, treatment duration is 3 (hip prosthesis) and 6 (knee prosthesis) months in patients undergoing débridement with implant retention, one-stage exchange, and two-stage exchange with a short interval of 2-3 weeks. According to a recent observational trial, a treatment duration of 2 and 3 months, respectively, is equivalent to the longer duration in patients undergoing débridement and implant retention. The optimal surgical therapy should be chosen according to a rational algorithm. It is crucial choosing the optimal surgical intervention from the beginning, because the final functional success depends on the cure by the first attempt.