AB0646 Intra-articular level of c-reactive protein in diagnosis of prosthetic knee infection

Background Periprosthetic joint infection is a rare but potentially serious complication. In 2012, Parvizi et al. suggested intra-articular C-reactive protein (CRP) could be used as a diagnosis marker of periprosthetic joint infection, with a threshold of 9.5mg/L1. Objectives The aim of our study was to analyse variations of CRP in synovial fluid between patients with native or prosthetic knee and find a threshold predictive of prosthetic knee infection. Methods From February to August 2012, 31 patients were included in our study: 10 patients with effusion in their native joint, 11 with aseptic effusion on prosthetic knee, 10 patients with a prosthetic knee infection according to the 2011 Muskuloskeletal Society criteria. All cases underwent joint aspiration. Intra-articular CRP level was determined by nephelometry and compared to seric CRP. Results Intra-articular CRP level was increased in patients with prosthetic knee infection compared to patients without prosthesis or aseptic prosthesis (respectively 24.4mg/L, 1.91 mg/L, 3.69mg/L; p=0.012, p