This document discusses periprosthetic joint infection (PJI). It defines PJI and lists risk factors. The pathogenesis involves initial bacterial adherence and biofilm formation, making infection difficult to treat. Diagnosis involves blood tests, joint aspiration and imaging. Treatment options include debridement with implant retention using antibiotics, one-stage or two-stage implant revision, long-term antibiotics, or joint fusion if infection cannot be eradicated. Intraoperative testing helps confirm PJI diagnosis to guide treatment.

1. By
Fahad AlKhalaf
R4

2.  Definition of periprosthetic infection
 Incidence and Risk factors
 Classification
 Pathogenesis
 Case discussion
 Diagnosis
 Treatment
 Recommendations

3. • Musculoskeletal Infection Society (MSIS) proposed a standard
definition for periprosthetic infection in 2011 that can be universally
adopted by all.
 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

4.  Four of the following six criteria exist:
• a. Elevated serum erythrocyte sedimentation rate (ESR) or serum C-reactive
protein (CRP) concentration
• b. Elevated synovial white blood cell (WBC) count
• c. Elevated synovial neutrophil percentage (PMN%)
• d. Presence of purulence in the affected joint
• e. Isolation of a microorganism in one culture of periprosthetic tissue or fluid
• f. Greater than five neutrophils per high-power field in five high-power fields
observed from histologic analysis of periprosthetic tissue at 400 times
magnification

5. • Incidence:
 of 1% to 2% at 2 years postoperatively for both total hip and knee arthroplasty
 up to 7%after revision surgery.
• Risk factors:
 Rheumatoid arthritis, psoriasis, immunosuppression, steroid therapy, poor
nutritional status, obesity, diabetes mellitus and extremely advanced age.

7. • Initial phase of adherence
 The pathogenesis of implant-associated infection
involves interaction between the microorganisms,
the implant and the host
 Rapid attachment to the surface of the implant
mediated by nonspecific factors (such as surface
tension, hydrophobia, and electrostatic forces), or
by specific adhesions.

8. • Accumulative phase
 During which bacterial cells adhere to each other and form a biofilm, a process
that is mediated by the polysaccharide intercellular adhesin (PIA) encoded by the
ica operon
• Existence within a biofilm represents a basic survival mechanism by which
microbes resist against external and internal environmental factors, such as
antimicrobial agents and the host immune system.

9. • 65 yrs old male , C/O Right knee pain , swelling ,
reduced ROM x 2 days .
• PMHx: DM , HTN , IHD
• SHx: Bilateral TKR 2yrs ago

10. • Ex:
• swollen knee with ROM from 5° to 100° (Extreme of motion is painful).
• no instability of the knee,
• extensor mechanism is intact with good patellar tracking.
• A previous incision is healed. slightly warm, tender in the medial joint line.
The NV normal.
• The skin is intact

11. • Blood tests :
 WBC : Blood leukocyte count and differential are not sufficiently
discriminative to predict the presence or absence of infection.
 CRP & ESR : “ We recommend erythrocyte sedimentation rate (ESR) and C-
reactive protein (CRP) level testing for patients assessed for PJI. Strength of
Recommendation: Strong ”

12. • Aspiration: in TKR
 “We recommend joint aspiration of patients being assessed for periprosthetic
knee infections who have abnormal ESR and/or CRP level results.”
 Sent for microbiologic culture, synovial fluid white blood cell count, and
differential white blood cell count.
 Strength of Recommendation: Strong

13.  “Studies suggest that either a synovial
fluid white blood cell count >1,700
cells/μL (range, 1,100 to 3,000
cells/μL) or a neutrophil percentage
>65% (range, 64% to 80%) is highly
suggestive of chronic periprosthetic
infection”

14. • Aspiration : in THR
 According to the American Academy its only recommended in low
probability infected hip with abnormal ESR & CRP with no
reoperation plan.

15. • Imaging:
 Plain films : A rapid development of a
continuous radiolucent line of greater
than 2 mm or severe focal osteolysis
within the first year is often associated
with infection.

16. • Nuclear imaging: has an excellent sensitivity, but a low specificity for
diagnosing prosthetic joint infection.
 “ is an option in patients in whom diagnosis of PJI has not been established
and who are not scheduled for reoperation. Strength of Recommendation:
Weak ”

17. • CT & MRI : “ We are unable to recommend for or against CT or MRI as a
diagnostic test for PJI. Strength of Recommendation: Inconclusive”
• MRI displays greater resolution for soft tissue abnormalities than CT or
radiography and greater anatomical detail than radionuclide scans.
• The main disadvantages of CT and MRI are imaging interferences in the
vicinity of metal implants

18. • Debridement, antibiotics and implant retention (DAIR) :
 Conservative surgical management involves debridement of a joint with exchange of
modular components and/or liners but retaining the prosthesis itself, combined with
prolonged antibiotic therapy (the DAIR strategy).
 Outcomes are best in those patients with a short duration of symptoms, a well-fixed and
functional implant and ideally with well-characterized microbiology demonstrating a
highly susceptible organism

19. • Implant revision :
 One-stage procedure : involves sampling, removal of the infected joint and all
cement, thorough debridement followed by re-scrubbing, re-draping and
insertion of a new prosthesis
 Intra-operative samples for culture and histology are taken from joint fluid,
joint capsule (hip), and synovium (knee), infected collections and membrane
from each interface as prosthetic components are removed
 Appropriate for those too frail to withstand two procedures andthe demanding
rehabilitation or patients intact or only slightly compromised soft tissues

20.  Two-stage procedure : intra operative separates sampling, joint removal,
thorough debridement and closure (the first-stage).
 Antibiotic cement spacer is essential for knee joints and may be used for hips.
 Subsequent re-insertion by weeks or months.

22. • Antibiotics :
 One-stage revisions : The optimum duration of antibiotic treatment following
a one stage revision is not known and reports range from 1 week to several
months.
 Two-stage procedure : with a long interval (8 weeks) is chosen, all foreign
bodies are removed and no spacer is inserted. In such patients, antimicrobial
therapy is shortened to 6 weeks.
 If cultures of intra-operative specimens remain negative, treatment is stopped,
otherwise it is continued for 3 - 6 months
 The suggested treatment : Intravenous treatment should be administered for the
first 2–4 weeks, followed by oral therapy 3 months for hip prostheses and 6
months for knee prostheses

24. • Joint removal or fusion :
 When patient’s condition is inappropriate to for revision or unable to have
functional prosthesis, or cases repeated attempts at revision and salvage may
fail to eradicate infection.

25. • Use of intraoperative Gram stain to rule out PJI is not recommended
• Use of frozen sections of peri-implant tissues in patients who are undergoing reoperation
for whom the diagnosis of PJI has not been established or excluded is strongly
recommended
• Antibiotics should be initiated after aspiration or cultures been obtained .
• Patients be off antibiotics for a minimum of 2 weeks before obtaining intra-articular
culture