The Musculoskeletal Infection Society workgroup proposed one standard definition of periprosthetic joint infection after hip and knee arthroplasty for clinical care, surveillance and research.
Consensus statement from a 2011 MSIS workshop, after 6 months of evidence review by MSIS executive members and a group of outside experts.
Methods
Panel
MSIS executive members and invited PJI experts
Method
6 months of email review
Workshop at the 2011 MSIS meeting
Evidence basis
Published studies of PJI tests
Serum and synovial markers
Culture
Histology
Recommendations
PJI is definite with a sinus tract to the prosthesis, a pathogen cultured from at least 2 separate samples, or at least 4 of 6 further criteria.
In the panel's view, a single positive culture of a low‑virulence organism (coagulase‑negative Staphylococcus, P. acnes, Corynebacterium) without other criteria does not establish definite PJI.
The panel acknowledged that low‑grade infections such as P. acnes may fail to meet the criteria despite true PJI.
The workgroup recommends 3 to 5 periprosthetic culture specimens, incubated both aerobically and anaerobically.
The panel notes that Gram stain is insensitive for PJI on periprosthetic samples.
Citing earlier reports, the panel warns that ESR and CRP can stay elevated for about 30 to 60 days after surgery.
Board pearl
Raised serum ESR and raised CRP count together as 1 of the 6 further criteria, not as 2.
MSIS definition of PJI (2011)Parvizi, Clin Orthop Relat Res 2011
Either one is sufficient
Sinus tract that communicates with the prosthesis
Pathogen grown from 2 or more separate periprosthetic tissue or fluid cultures
Or 4 of these 6
Raised serum ESR and raised serum CRP (together count as 1 criterion)
Raised synovial leukocyte count
Raised synovial neutrophil percentage (PMN%)
Purulence in the affected joint
Microorganism in a single periprosthetic tissue or fluid culture
Over 5 neutrophils per high‑power field across 5 high‑power fields on periprosthetic tissue histology (×400)
PJI may still be present when fewer than 4 minor criteria are met.
Authors' conclusion
Using this definition, clinicians can be confident in their diagnosis and therefore provide appropriate treatment.
The Musculoskeletal Infection Society workgroup proposed one standard definition of periprosthetic joint infection after hip and knee arthroplasty for clinical care, surveillance and research.
Consensus statement from a 2011 MSIS workshop, after 6 months of evidence review by MSIS executive members and a group of outside experts.
Methods
Panel
MSIS executive members and invited PJI experts
Method
6 months of email review
Workshop at the 2011 MSIS meeting
Evidence basis
Published studies of PJI tests
Serum and synovial markers
Culture
Histology
Recommendations
PJI is definite with a sinus tract to the prosthesis, a pathogen cultured from at least 2 separate samples, or at least 4 of 6 further criteria.
In the panel's view, a single positive culture of a low‑virulence organism (coagulase‑negative Staphylococcus, P. acnes, Corynebacterium) without other criteria does not establish definite PJI.
The panel acknowledged that low‑grade infections such as P. acnes may fail to meet the criteria despite true PJI.
The workgroup recommends 3 to 5 periprosthetic culture specimens, incubated both aerobically and anaerobically.
The panel notes that Gram stain is insensitive for PJI on periprosthetic samples.
Citing earlier reports, the panel warns that ESR and CRP can stay elevated for about 30 to 60 days after surgery.
Board pearl
Raised serum ESR and raised CRP count together as 1 of the 6 further criteria, not as 2.
MSIS definition of PJI (2011)Parvizi, Clin Orthop Relat Res 2011
Either one is sufficient
Sinus tract that communicates with the prosthesis
Pathogen grown from 2 or more separate periprosthetic tissue or fluid cultures
Or 4 of these 6
Raised serum ESR and raised serum CRP (together count as 1 criterion)
Raised synovial leukocyte count
Raised synovial neutrophil percentage (PMN%)
Purulence in the affected joint
Microorganism in a single periprosthetic tissue or fluid culture
Over 5 neutrophils per high‑power field across 5 high‑power fields on periprosthetic tissue histology (×400)
PJI may still be present when fewer than 4 minor criteria are met.
Authors' conclusion
Using this definition, clinicians can be confident in their diagnosis and therefore provide appropriate treatment.