Review of Frozen Section Results
and correlation with microbiology
for revision joint replacement
surgery
Dr R Hadden BSc MBBS
SpR Histopathology
Derriford Hosptial
Revision Surgery
• Currently Frozen Section is considered by
Orthopaedic surgeons as a vital tool in
assessment of periprosthetic joint infections.
• Main Indications – aseptic or septic loosening
• Intraoperative decision on type of procedure
– One stage
– Two stage
Problems
• No agreed Gold Standard single test for
diagnosing periprosthetic joint infections (PJI).
• International Consensus Meeting on PJI.
PJI Is Present When One of the Major Criteria Exists or Three Out of Five Minor Criteria
Exist
Major Criteria
Two positive periprosthetic cultures with
phenotypically identical organisms, OR
A sinus communicating with the joint, OR
1) Elevated serum C-reactive protein (CRP)
AND erythrocyte sedimentation rate (ESR)
Minor Criteria
2) Elevated synovial fluid white blood cell
(WBC) count OR ++change on leukocyte
esterase test strip
3) Elevated synovial fluid
polymorphonuclear neutrophil percentage
(PMN%)
4) Positive histological analysis of
periprosthetic tissue
5) A single positive culture
Criterion
Acute PJI (< 90 days)
Chronic PJI (> 90 days)
Erythrocyte Sedimentation
Rate (mm/hr)
Not helpful. No threshold
was determined
30
C-Reactive Protein (mg/L)
100
10
Synovia White Blood Cell
Count (cells/μl)
10,000
3,000
Synovial
Polymorphonuclear (%)
90
80
Leukocyte Esterase
+ Or ++
+ Or ++
Histological Analysis of
Tissue
> 5 neutrophils per high
power field in 5 high
power fields (× 400)
Same as acute
Local guidelines
• No universally agreed gold standard (even within local team)
• Based on the number of polymorphs per high powered field in at
least five separate fields
– <5 - indicates no active infection and one stage advised
– 5-10 - possible infection, surgeon preference along with clinical
picture to dictate surgical management
– >10 - indicative of active infection, requiring two stage surgical
management
Recent Series Of 15 Patients
• If “clear operative field” and <20neuts/hpf
– an infection free outcome is possible after single stage
re-implantation
• If “poor surgical field appearances”, associated
with >20neuts/hpf. 2 stage procedure done.
• Confirms our anecdotal evidence that positive
frozen sections are macroscopically abnormal
(colour/texture/odour).
Conflicting evidence
• Cut off 10 or 20 neuts/hpf?
• Do surgeons actually comply with local
guidelines?
Results
• Reports on 50 sequential samples were
reviewed
• The microbiology results were reviewed
• Correlation between the two was assessed
Frozen results
• 8 positive (>10 neuts/hpf)
• 36 Negative
• 6 Equivocal (5-9 neuts/hpf)
Positive FS
• Of the 8 positive Frozen sections:
– All confirmed on paraffin
– 4 grew organisms
• 1 on initial culture
• 3 on “enrichment”
Negative FS
• 34/36 confirmed on paraffin
• 2/36 cases 0 neuts on frozen, “small numbers”
on later paraffin sections
– Likely negative
• 24/36 grew organisms
– 1 on culture
– 23 on enrichment culture
Equivocal / Borderline
• 6 cases 5-9 neuts/hpf
– 4 with growth on enrichment culture
– 2 with no growth
– All had no growth on initial culture
Results
Negative frozen
section
Equivocal frozen
section
Positive frozen
section
Single stage
operation
110
4
Two stage
operation
28
5
2
Other
0
0
1
0
Summary
• Negative result: 25% go on to have 2-stage
procedure!
• Equivocal result: 50/50 split – presumably
based on clinical/other test results
• Positive result: Good compliance (n)
Results
Negative frozen
section
Equivocal frozen
section
Positive frozen
section
Negative
Cultures
101
4
1
Positive
Cultures
36
5
2
Results
Negative frozen
section
Equivocal frozen
section
Positive frozen
section
Required
Revision
17
2
0
No Further
Revision
121
7
2
• 12% with negative FS required revision
• 22% with equivocal FS required revision
• 0% with positive FS required revision
Discussion
• Why do surgeons ignore negative result in 25% of
cases?
What is the point of FS in these cases?
• In equivocal FS cases, what determines the
procedural outcome? Does FS really make a
difference?
• 2011-2012 approximate costs of £15,000.
Histology concerns:
• Anecdotally, positive FS correlates with macro
findings.
– In the Korean series, high numbers of neuts
correlated with macroscopic impression.
• The 0-5, 5-10, 10+ criteria are arbitrary and
based only on one study.
• Recent criteria use histology (not necessarily
FS histology!) as only a minor criteria for PJI.
Microbiology concerns:
• Correlation with microbiology results is
difficult.
– Confounding factors (pre/intraop abx).
– Most growth is on “enrichment culture”, we do
not know the significance of these results.
Learning points / Questions
• Negative predictive value is published as the most
important factor in intraoperative testing
• Why did many –ve FSs have +ve micro? ?sampling
or FS poor sensitivity
• 25% of negative frozen sections still had a 2-stage
procedure
• Is there another test or clinical parameter that
“trumps” frozen section?
• Targeted or limited use should be advised (JK
agrees this – reaudit needed to confirm)