Portsmouth Audit Portsmouth Audit

Discussion Discussion -- February 2007February 2007

Management of infection Management of infection

in Total Hip and Knee in Total Hip and Knee

ArthroplastyArthroplasty

Simon TilleySimon Tilley

An Interdisciplinary ChallengeAn Interdisciplinary Challenge

Many aspects of Rx controversialMany aspects of Rx controversial

DiagnosisDiagnosis

Role of debridement & washoutRole of debridement & washout

1 stage vs 2 stage revision1 stage vs 2 stage revision

Local vs systemic antibioticsLocal vs systemic antibiotics

Incidence of deep infectionIncidence of deep infection

Varies significantly between centresVaries significantly between centres

Quoted averages range Quoted averages range 00..6 6 –– 22%%

Treatment OptionsTreatment Options

Tailor to individualTailor to individual

Operative vs suppressiveOperative vs suppressive

Pathophysiology 1Pathophysiology 1

DIRECT DIRECT

Access of bacteria from pt, theatre, personnelAccess of bacteria from pt, theatre, personnel

At time of surgery or early postAt time of surgery or early post--opop

HAEMATOGENOUSHAEMATOGENOUS

Bacteraemic event at remote siteBacteraemic event at remote site

Can happen at any timeCan happen at any time

Note: Both significantly modulated by patient factorsNote: Both significantly modulated by patient factors

Prime SuspectsPrime Suspects

Staphylococci most commonly isolated organismsStaphylococci most commonly isolated organisms

Epidermidis Epidermidis > Aureus> Aureus

Others: Others: StrepStrep

EnterococciEnterococci

Gram + cocci Gram + cocci

Rare: Gram negativeRare: Gram negative

Fungi & Mycobacteria Fungi & Mycobacteria

The Race for the SurfaceThe Race for the Surface

Host tissue vs bacteria to colonise implant Host tissue vs bacteria to colonise implant surface.surface.

Prosthesis immediately coated with host Prosthesis immediately coated with host derived “conditioning film”.derived “conditioning film”.

Film acts as media for colonisation (host vs Film acts as media for colonisation (host vs pathogenic)pathogenic)

Bacteria approach TJA through interaction of Bacteria approach TJA through interaction of physical & chemical forcesphysical & chemical forces

Pathophysiology 2Pathophysiology 2

If bacteria win race they will bind & multiplyIf bacteria win race they will bind & multiply

Prosthesis inert with no innate protectionProsthesis inert with no innate protection

S. aureusS. aureus = Affinity for metal alloys= Affinity for metal alloys

Pseudomonas Pseudomonas = Prefers polymers= Prefers polymers

Abx can also interact with implant surface to inhibit Abx can also interact with implant surface to inhibit

bacterial adherencebacterial adherence

The Glycocalyx & Antibiotic ResistanceThe Glycocalyx & Antibiotic Resistance

Most infecting organisms produce GlycocalyxMost infecting organisms produce Glycocalyx

Enhances nutritionEnhances nutrition

Exopolysaccharide barrier to host defencesExopolysaccharide barrier to host defences

Bacterial sequestration Bacterial sequestration

Result: Result: Decreased antibiotic penetrationDecreased antibiotic penetration

Increased antibiotic resistanceIncreased antibiotic resistance

Esp: S. aureus, CNS e.g. S. epidermidis & Pseudomonas sppEsp: S. aureus, CNS e.g. S. epidermidis & Pseudomonas spp

PrePre--operative diagnosis of deep operative diagnosis of deep

infectioninfection

Hx & Exam both highly variable (Hx & Exam both highly variable (IV/CIV/C))

Mostly mildMostly mild--moderate painmoderate pain

Less frequently: Less frequently:

Deep throbbing painDeep throbbing pain

Wound drainageWound drainage

ErythemaErythema

SwellingSwelling

Systemic fever, chills, malaiseSystemic fever, chills, malaise

Initial InvestigationsInitial Investigations

Plain radiographs (Plain radiographs (IIb/BIIb/B))

FBC + diff (FBC + diff (IIb/BIIb/B))

ESR (ESR (IIb/BIIb/B))

CRP (CRP (IIb/BIIb/B))

ESR & CRP 1ESR & CRP 1 Non specific indicators of systemic response to Non specific indicators of systemic response to

inflammatory processesinflammatory processes

ESR can remain elevated for 1 yr post THAESR can remain elevated for 1 yr post THA

CRP returns to baseline @ ~3/52 postCRP returns to baseline @ ~3/52 post--op (range 1op (range 1--8/52)8/52)

TestTest

SensitivitySensitivity SpecificitySpecificity PPVPPV NPVNPV

ESR (>30)ESR (>30) 0.820.82 0.850.85 0.580.58 0.950.95

CRP (> 10)CRP (> 10) 0.960.96 0.920.92 0.740.74 0.990.99

ESR + CRPESR + CRP 0.830.83 1.001.00

ESR & CRP 2ESR & CRP 2

NPV of a low ESR (~95%) more useful than NPV of a low ESR (~95%) more useful than

raised ESR (PPV 58%)raised ESR (PPV 58%)

Accuracy optimised with:Accuracy optimised with:

Combination ESR + CRPCombination ESR + CRP

Serial measurementsSerial measurements

Radiographic FindingsRadiographic Findings

Rarely diagnosticRarely diagnostic

Important to rule out other Important to rule out other sources of pain (e.g. #, HO, sources of pain (e.g. #, HO, prosthesis failure)prosthesis failure)

Infection suggested by Infection suggested by radiolucent lines, osteolysis radiolucent lines, osteolysis and scalloping or and scalloping or periosteal periosteal new bone formationnew bone formation

Speed of progression: Septic Speed of progression: Septic > Aseptic> Aseptic

RadioRadio--isotope scanning isotope scanning ((IIb/BIIb/B))

Can be useful if Can be useful if prosthesis > 18/12 prosthesis > 18/12

False Neg when False Neg when infective process infective process interferes with local interferes with local blood supplyblood supply

Addition of Ga 67 Addition of Ga 67 citrate > Tc 99citrate > Tc 99--m m alone.alone.

Aspiration / Biopsy Aspiration / Biopsy ((IIb/BIIb/B))

Allows preAllows pre--op op ΔΔ of infective of infective organismorganism

Note: Barrack paper (JBJS 1993). Note: Barrack paper (JBJS 1993). Advises against aspirAdvises against aspirnn in all in all revision casesrevision cases

High PPV but less useful if High PPV but less useful if prosthesis > 5ys or if normal prosthesis > 5ys or if normal bloodsbloods

Remember to stop Abx 2Remember to stop Abx 2--3/52 3/52 beforebefore

AspirAspirn n = B= Bx x (Williams 2004)(Williams 2004)

AuthorAuthor SensitivitySensitivity SpecificitySpecificity

Elson 1991Elson 1991 8484 8787

Roberts Roberts

19921992

8787 9595

Lachiewicz Lachiewicz

19961996

9292 9797

Spangehl Spangehl

19991999

8686 9494

Williams Williams

20042004

8080 9494

AvAv 8686 9393

OthersOthers

Frozen Section Frozen Section ((IIb/BIIb/B)) ::

Supplements surgical specimensSupplements surgical specimens

10 PMN / HPF = Sens 84%, Spec 99%10 PMN / HPF = Sens 84%, Spec 99%

PCR PCR ((IIb/BIIb/B)) ::

Pros: Allows detection in small numbers Pros: Allows detection in small numbers

Cons: Cost, no sensitivities, does not identify Cons: Cost, no sensitivities, does not identify primary agent among mixed growthprimary agent among mixed growth

Interventions 1 Interventions 1 –– Surgical DebridementSurgical Debridement

Depends on timing:Depends on timing:

≥≥ 33//52 52 = = 8484% success% success

33--66//52 52 = = 5656%%

Note:Note:

Infected THR tend to present later than TKRInfected THR tend to present later than TKR

Haematogenous infection often delayed c.f directHaematogenous infection often delayed c.f direct

Interventions 2 Interventions 2 –– Surgical prosthesis Surgical prosthesis

exchangeexchange

1 vs 2 stage 1 vs 2 stage

Best chance of maximising function & clearing Best chance of maximising function & clearing

infectioninfection

Vital that micro is as accurate & Vital that micro is as accurate &

comprehensive as posscomprehensive as poss

5x tissue specimens (new scalpel + forceps for 5x tissue specimens (new scalpel + forceps for

each)each)

Early transfer of specimens to labEarly transfer of specimens to lab

Withold intraWithold intra--op Abx until samples obtainedop Abx until samples obtained

Direct Exchange Direct Exchange ((III/BIII/B))

Improved efficacy cf debridement aloneImproved efficacy cf debridement alone

Avoids morbidity of temporary pseudarthrosis & 2Avoids morbidity of temporary pseudarthrosis & 2ndnd

major proceduremajor procedure

No opportunity for soft tissue contractureNo opportunity for soft tissue contracture

Improved outlook if good bone stockImproved outlook if good bone stock

BUTBUT

Less successful than 2 stage esp with virulent / Less successful than 2 stage esp with virulent / resistant organisms resistant organisms ( Ure K J ( Ure K J et al et al JBJS JBJS AmAm 1998)1998)

Staged Exchange Staged Exchange ((III/BIII/B))

Gold Standard?Gold Standard?

Local antibiotics +/Local antibiotics +/-- systemic (patchy evidence systemic (patchy evidence

for length of time with systemic Rx)for length of time with systemic Rx)

2 stage exchange with antibiotic spacer 2 stage exchange with antibiotic spacer

success > 90% success > 90% (Langlais F (Langlais F et al et al In: EFORT 2003) In: EFORT 2003)

SpacersSpacers

Aims:Aims:

Preserve normal relationship between structuresPreserve normal relationship between structures

Vector for local antibiotic RxVector for local antibiotic Rx

Allow reasonable attempts @ mobilisationAllow reasonable attempts @ mobilisation

Facilitate exposure @ reconstructionFacilitate exposure @ reconstruction

Straightforward to removeStraightforward to remove

Antibiotics 1 Antibiotics 1 ((III/BIII/B))

Systemic Systemic +/+/-- local local

Supplementary based on sensitivity profilesSupplementary based on sensitivity profiles Aminoglycosides e.g. GentamicinAminoglycosides e.g. Gentamicin

Glycopeptides e.g. VancomycinGlycopeptides e.g. Vancomycin

Theoretical risk of lowering mechanical strength of cement Theoretical risk of lowering mechanical strength of cement with addition of Abxwith addition of Abx

In In –– vivovivo studies suggest no decrease in strength at 13 yrs with studies suggest no decrease in strength at 13 yrs with 10% substitution (e.g. 4g Vanc / 40g Palacos)10% substitution (e.g. 4g Vanc / 40g Palacos)

Main aim is to eradicate infection. Sterile Main aim is to eradicate infection. Sterile mechanical failure preferable to septic failuremechanical failure preferable to septic failure

Antibiotics 2Antibiotics 2

Heat of cement exothermic rxn inactivates Heat of cement exothermic rxn inactivates

penicillinspenicillins

Rifampicin interfere with cement Rifampicin interfere with cement

polymerisation itselfpolymerisation itself

Timing of ReTiming of Re--implantationimplantation

Guided by:Guided by:

Clinical progressClinical progress

Serial ESR, CRPSerial ESR, CRP

? Neg joint aspirate/open biopsies after stopping ? Neg joint aspirate/open biopsies after stopping

AbxAbx

Cemented or Uncemented Prostheses? Cemented or Uncemented Prostheses?

((III/BIII/B))

Antibiotic impreg cement recommended for single Antibiotic impreg cement recommended for single

stage exchangestage exchange

Cement not mandatory for Cement not mandatory for 2 2 stage modelstage model

% Success% Success Direct ExchangeDirect Exchange TwoTwo--stage Revisionstage Revision

AntibioticAntibiotic--loaded loaded

cementcement

8686 9393

No antibioticNo antibiotic 5959 8686

Comparison of success rates for staged revision & the use of antibiotic-loaded cement

In 1641 patients collated from a nmber of individual studies (Langlais 2003)

Recommendations Recommendations –– Not controversialNot controversial

Multidisciplinary approachMultidisciplinary approach

Accurate culture & sensitivity reportsAccurate culture & sensitivity reports

Antibiotics tailored to sensitivities of infecting Antibiotics tailored to sensitivities of infecting

organismorganism

Effective debridement is keyEffective debridement is key

Tissue cultures if surgical procedure performedTissue cultures if surgical procedure performed

Local antibiotics +/Local antibiotics +/-- systemic improves systemic improves

clearanceclearance

IV/CIV/C

IV/CIV/C

IV/CIV/C

IV/CIV/C

IV/CIV/C

III/BIII/B

Ongoing DebateOngoing Debate

Limitations of debridement & washoutLimitations of debridement & washout

Role for direct exchangeRole for direct exchange

Acceptability of extra morbidity assoc with 2 Acceptability of extra morbidity assoc with 2

stage exchangestage exchange

Number of surgical attempts to clear infection Number of surgical attempts to clear infection

before microbefore micro--organism deemed unobtainableorganism deemed unobtainable

Thank youThank you