Have you ever asked a medical student or resident to define
periprosthetic joint infection? Most students would define it
as a condition in which an infecting organism is present in the prosthetic
joint. Although this is technically correct, it implies that isolation of an
organism, i.e. a positive culture would be the gold
standard for periprosthetic joint infection.
No one disputes that isolation of an organism is extremely important
aspect for confirmation of periprosthetic joint infection (PJI). However, all
of us in clinical practice dealing with PJI realize that there is a relatively
large number of patients (5% to 8%) suffering from PJI in whom an organism
cannot be isolated (culture negative), and conversely, there are some patients
(again 5% to 8%) with no sign of PJI in whom cultures obtained may isolate a
pathogen (false positive). Thus, positive culture is not a true gold
standard for defining PJI, a fact that most of us live with on a daily
basis. The question that arises is what then defines PJI?
One should not attempt to obtain an answer to this question from the
literature. There are no single accepted criteria for PJI currently.
Furthermore, some of these definitions even disagree with each other. There are
almost as many definitions or criteria for PJI in the literature as there are
published studies. It appears that institutions and investigators use a
self-selected criteria for defining PJI. The existence of different
diagnostic criteria or definition for PJI has made it complex to interpret the
literature related to PJI. This complexity or frustration is experienced by
hospitals attempting to report surgical site infections to the
National Healthcare Safety Network, the surveillance arm of
the Center for Disease Control and Prevention (CDC).
Musculoskeletal Infection Society convened a workgroup and
tasked them with evaluation of the literature to propose a diagnostic criteria.
The workgroup consisted of orthopedic surgeons, infectious disease specialists,
musculoskeletal pathologists and representatives from the CDC. The intention of
this proposal was to have a gold-standard definition for PJI that
can be universally adopted by all physicians, surveillance authorities
(including the CDC), medical and surgical journals, the medicolegal community
and all involved in management of PJI. Using this definition, clinicians can be
confident in their diagnosis and therefore provide appropriate treatment.
Additionally, adoption of this definition for research purposes will allow for
consistency between studies and potential improvement of the quality of the
published body of evidence. These definitions will be adopted and published by
most major orthopedic journals. The CDC has also expressed interest in adopting
these definitions for surveillance purposes.
Based on the recommendations of the workgroup, definite PJI is present
- There is a sinus tract communicating with the prosthesis; or
- A pathogen is isolated by culture from two separate tissue or fluid
samples obtained from the affected prosthetic joint; or
- When four out of the following six criteria exists: 1) elevated serum
erythrocyte sedimentation rate or serum C-reactive protein concentration, 2)
elevated synovial white blood cell count, 3) elevated synovial
neutrophil percentage, 4) presence of purulence in affected
joint, isolation of a microorganism in one culture of periprosthetic tissue or
fluid; or 5) greater than five neutrophils per high power field in five high
power fields observed from histological analysis of periprosthetic tissue at
400 times magnification.
However, PJI may be present if less than four of these criteria are met.
Moving forward, these definitions should be embraced by all to bring
harmony into a field that has experienced much variation and inconsistency.
- Berbari E, Mabry T, Tsaras G, et al. Inflammatory blood laboratory
levels as markers of prosthetic joint infection: A systematic review and
meta-analysis. J Bone Joint Surg Am.2010;92(11):2102-2109.
- Della Valle CJ, Sporer SM, Jacobs JJ, et al. Preoperative testing
for sepsis before revision total knee arthroplasty. J
- Ghanem E, Parvizi J, Burnett RSJ, et al. Cell count and
differential of aspirated fluid in the diagnosis of infection at the site of
total knee arthroplasty. J Bone Joint Surg
- Parvizi J, Ghanem E, Menashe S, et al. Periprosthetic infection:
what are the diagnostic challenges? J Bone Joint Surg Am. 2006;88
- Parvizi J, Jacovides C, Zmistowski B, Jung KA. Definition of
periprosthetic joint infection: is there a consensus? Clin Orthop Relat
Res. 2011. Available at:
http://www.ncbi.nlm.nih.gov/pub med/21751038 [Accessed July
- Trampuz A, Hanssen AD, Osmon DR, et al. Synovial fluid leukocyte
count and differential for the diagnosis of prosthetic knee infection. Am
J Med. 2004;117(8):556-562.
- Javad Parvizi, MD, FRCS, editor of Infection Watch, can be
reached at the Rothman Institute, 925 Chestnut St., 5th Floor, Philadelphia, PA
19107; 267-339-3617; email: firstname.lastname@example.org.
- Disclosures: Parvizi is a consultant to Stryker.