THE ROLE OF ANTIMICROBIAL AGENTS IN THE M ANAGEMENT OF INFECTED ARTHROPLASTIES

Infection is a rare, but extremely severe, complication of prosthetic joint surgery. Until recently, antimicrobial agents were not generally used in the management of such infections. Antibiotics now have an im portant role, either combined with replacement surgery or even as the only treatment in selected cases. In earlier studies, high failure rat es were reported with conservative therapy. These unsatisfactory resul ts were probably due to a lack of collaboration between surgeons, infe ctious disease specialists and microbiologists. All patients with a lo ng history of infection or with loosened implants should undergo joint replacement. Early or rapidly diagnosed hematogenous infection in pat ients with stable prostheses can be treated conservatively. In most ca ses, such a treatment is preceded by revision surgery, which is needed for microbiological diagnosis and for debridement. The choice of anti biotics depends on the microorganism involved and the results of susce ptibility testing. The most important etiologic agents are Staphylococ cus aureus and coagulase-negative staphylococci. Antimicrobial drugs u sed in device-related infections should act on surface-adherent and st ationary-phase bacteria. In an animal model, rifampin combined with a quinolone has proved to have the highest cure rate against staphylococ cal foreign-body infection. Rifampin is indeed highly efficacious on s urface-adherent and stationary-phase bacteria. These experimental data were confirmed in clinical studies; cure rates of 60-80 % were observ ed with rifampin combinations without joint replacement. Antimicrobial therapy should bei continued over at least 3 months in hip implant in fection and at least 6 months in knee implant infection. Before treatm ent ist stopped, signs and symptoms of infection must have been absent with C-reactive protein normal for at least 1 month.