人工關節感染的新定義

美國各個相關學會及CDC都同意的人工關節感染新診斷標準

 

New Criteria for Periprosthetic Joint
Infection Recommended CME

News Author: Laurie Barclay, MD

CME Author: Penny Murata, MD

Clinical Context

One of the most common complications of lower extremity
joint arthroplasty is periprosthetic joint infection (PJI). However, some of
the definitions of PJI conflict with each other, according to Parvizi and
colleagues in the November 2011 issue of Clinical Orthopaedics and Related
Research. The Musculoskeletal Infection Society convened a workgroup to
analyze the literature on the definition of PJI.

This statement from the 2010 meeting of the Musculoskeletal
Infection Society by Parvizi and colleagues proposes a new definition for PJI
that can be used by clinicians, surveillance authorities, and researchers.

Study Synopsis and Perspective

A new evidence-based definition and diagnostic criteria for
PJI should improve uniformity of diagnosis, treatment, and surveillance,
according to a symposium paper published in the November issue of Clinical
Orthopaedics and Related Research. The new criteria will also be published
in the December issue of the Journal of Arthroplasty.

"Our aim was to develop a 'gold standard' definition to
serve as a roadmap for diagnosing patients with suspected PJI that could be
universally adopted by the industry," lead author Javad Parvizi, MD,
director of research at the Rothman Institute at Thomas Jefferson University in
Philadelphia, Pennsylvania, said in a news release. Dr. Parvizi led the
Musculoskeletal Infection Society working group that wrote the new definition.

Increasing prevalence of PJI was a major impetus behind the
new definition, as deep PJI is now the leading indication for revision of total
knee arthroplasty and the third most common indication for revision of total
hip arthroplasty. Physicians have also become increasingly concerned about a
rise of PJI attributed to antibiotic-resistant Staphylococcus aureus and
other drug-resistant bacteria.

"It's important to get to the root of the cause of PJI
so that we can begin to get ahead of it at Jefferson and across the industry
and turn the tide," Dr. Parvizi said. "Using this definition, we will
now be more confident in our diagnosis and be able to provide appropriate
treatment for patients."

Definition of PJI

"Patients with PJI could suffer unintended consequences
if their infection is not identified and treated hastily," Dr. Parvizi
noted in the release. "Without an industry-wide definition, research,
diagnosis and treatment cannot be uniform."

Criteria for definite PJI are as follows:

1. a sinus tract is present
   communicating with the prosthesis; or


2. two or more separate tissue or
   fluid samples obtained from the affected prosthetic joint are
   culture-positive for a pathogen; or


3. four of the following 6
   criteria are present:




1. elevated erythrocyte
   sedimentation rate (ESR) and serum C-reactive protein (CRP)
   concentration,


2. elevated synovial leukocyte
   count,


3. elevated synovial percentage
   of neutrophils (PMN%),


4. purulence in the affected
   joint,


5. one culture of periprosthetic
   tissue or fluid is positive for a microorganism, or


6. histologic analysis of
   periprosthetic tissue at x400 magnification reveals more than 5
   neutrophils per high-power field (HPF) in 5 HPFs.

If fewer than 4 of these criteria are met, PJI may still be
present.

To date, the Knee Society, the Hip Society,
the Infectious Diseases Society of North America, the American
Academy of Orthopaedic Surgeons, and the US Centers for Disease Control
and Prevention have reviewed and endorsed the new definition.

"We recognize there are numerous other tests currently
being evaluated, including measurement of [CRP] from the synovial fluid,
synovial leukocyte esterase, sonication of explanted prosthetics, and molecular
techniques such as [polymerase chain reaction] and other molecular markers such
as [interleukin 6]," the symposium paper authors conclude. "As these
or other techniques become validated and widely available, the currently
proposed definition may require modification."

The authors of the symposium paper report no financial
disclosures.

Clin Orthop Relat Res.
2011;469:2992-2994. Full text

Study Highlights

• The proposed new definition of
  definite PJI is one of the following 3:




• Sinus tract communicating with
  the prosthesis


• Pathogen isolated by culture
  from at least 2 separate tissue or fluid samples obtained from the
  affected prosthetic joint


• 4 of the following 6 criteria:
  




1. Elevated serum ESR and serum
   CRP levels


2. Elevated synovial leukocyte
   count


3. Elevated PMN%


4. Purulence in the affected
   joint


5. Isolation of a microorganism
   in 1 culture of periprosthetic tissue or fluid or


6. More than 5 neutrophils per
   HPF in 5 HPFs observed from histologic analysis of periprosthetic tissue
   at x400 magnification






• PJI is possible if less than 4
  of these criteria exist.


• Periprosthetic tissue or fluid
  must be obtained.


• Each sample requires separate,
  sterile instruments.


• At least 3, and no more than 5,
  periprosthetic specimen samples are recommended.


• Routine aerobic and anaerobic
  incubation are recommended.


• Fungal and mycobacterial
  cultures should be reserved for higher-risk cases.


• Time of culture incubation is
  not standardized.


• Isolation of a single virulent
  organism, including S aureus, might indicate PJI.


• Isolation of a single
  low-virulent organism, including coagulase-negative Staphylococcus,
  Propionibacterium acnes, or Corynebacteria, without other
  criteria does not seem to indicate definite infection.


• A Gram stain of periprosthetic
  tissue or fluid is not sensitive for the diagnosis of PJI.


• Elevated levels of serum tests
  are an ESR of more than 30 mm/hour and CRP of more than 10 mg/L.


• ESR and CRP levels can be
  affected by laboratory site, age, sex, comorbidities, and postoperative
  status.


• Synovial leukocyte count and
  PMN% thresholds are not clear.


• For chronically infected knee
  arthroplasty, the reported synovial leukocyte count is 1100 to 4000
  cells/µL and PMN% is 64% to 69%.


• For acute infection, defined as
  less than 3 months from the index surgery or onset of symptoms, synovial
  leukocyte count is 20,000 cells/µL and PMN% is 89%.


• For the infected hip
  arthroplasty, one study reported a threshold synovial leukocyte count of
  3000 cells/µL and a PMN% of 80%.


• Surgeons and histopathologists
  should be in agreement on the diagnosis of PJI.


• The histopathologist should
  disregard neutrophils entrapped in superficial fibrin or adherent to
  endothelium or small veins.


• Elevated neutrophil count might
  occur in recent periprosthetic fractures or inflammatory arthropathy.


• Other tests that are being
  evaluated include synovial fluid CRP, synovial leukocyte esterase,
  sonication of explanted prosthetics, polymerase chain reaction, and serum
  interleukin-6 markers.

Clinical Implications

• The proposed new definition for
  definite PJI includes the sinus tract communicating with the prosthesis, a
  pathogen isolated by culture from at least 2 separate tissue or fluid
  samples from the prosthetic joint, or 4 of 6 criteria involving elevation
  of various synovial and inflammatory markers and histologic analyses of
  neutrophils or periprosthetic tissue.


• Recommendations for
  microbiologic testing for PJI include using separate, sterile instruments
  for each sample; obtaining at least 3, and no more than 5, periprosthetic
  specimens; incubating in aerobic and anaerobic cultures; and reserving
  fungal and mycobacterial cultures for higher-risk scenarios.