The Natural Progression of Synovial Fluid White Blood-Cell Counts and the Percentage of Polymorphonuclear Cells After Primary Total Knee Arthroplasty

Abstract

The synovial fluid WBC count and PMN percentage changed at different rates over the first two years after total knee arthroplasty, with the WBC count exhibiting an initially more rapid decrease and the PMN percentage demonstrating a more linear decrease. Hence, the total neutrophil count, which combines these two parameters, may provide a better method to identify patients with a periprosthetic joint infection. Values for the synovial fluid WBC count, PMN percentage, and total neutrophil count were all significantly elevated in the early postoperative period, and the use of standard cutoff values for the diagnosis of periprosthetic joint infection can lead to false-positive results.