Table 1 MSIS criteria^a

Major criteria

1) Two positive periprosthetic cultures with phenotypically identical organisms

2) A sinus tract communicating with the joint

Minor criteria

1) Elevated serum C-reactive protein (> 10 mg/L) and erythrocyte sedimentation rate (> 30 mm/h)

2) Elevated synovial fluid white blood cell count (> 3000 cells/mL) or change on a leukocyte esterase test strip (+ or + +)

3) Elevated synovial fluid polymorphonuclear neutrophil percentage (> 80%)

4) Positive histological analysis of periprosthetic tissue (> 5 neutrophils/HPF) based on the examination of 5 HPFs

5) A single positive culture