Definition of prosthetic joint infection by infectious disease society of America (IDSA), 2012:
PJI is present when one of the following criteria is present:
- Sinus tract communicating with a prosthesis
- Presence of pus
- Acute inflammation on histopathologic evaluation of periprosthetic tissue
- Two or more positive cultures with the same organism (intraoperatively and/or preoperatively)
- Single positive culture with the virulent organism.
| Type of infection | Time of PJI | Likely Source of infection |
| Early | Less than 3 months | Intraoperative |
| Delayed | 3-12 months | Intraoperative |
| Late | More than 12 months | Haematogenous or Intraoperative |