Table 1.

Inclusion and exclusion criteria of the study

Inclusion criteria	Exclusion criteria
Any of the following suspicious signs or symptoms of chronic knee PJI (more than 90 d), as following:	Acute signs or symptoms of knee infection (less than 90 d)
Persistent knee pain (more than 3 mo), without other apparent cause
Persistent joint effusion (more than 3 mo)
Persistent local heat (more than 3 mo)
Presence of draining sinus
Early failure of the prosthesis (less than 5 yr)
Radiographic findings suggesting infection[33]
Have not used antibiotics for at least 4 wk before the evaluation	Insufficient synovial fluid volume during knee aspiration
	Insufficient data for fulfilling the periprosthesis infection criteria[11]

PJI: Periprosthetic joint infection.