orthopaedics

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