Antibiotic Elution After Two-stage Knee Revision

The goal of this observational study is to monitor the eluted antibiotic concentrations of gentamicin and vancomycin by a static knee cement spacer in patients being treated for periprosthetic infections of the knee. The main question aims to answer if eluted antibiotics are in a therapeutic range for treatment at sight of infection. Secondarily, local antibiotic concentrations are compared with systemic blood levels, as are systemically applied antibiotics compared to intra-articular concentrations. Intra-articular samples are collected over a 72 hour postoperative period.