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Diagnosis and Treatment of Infection Following Total Hip Arthroplasty

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Type-III Infections These are the least common and ... removal of a well-fixed total hip implant carries the risk of ... it usually is associated with a ... – PowerPoint PPT presentation

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Title: Diagnosis and Treatment of Infection Following Total Hip Arthroplasty


1
Diagnosis and Treatment of Infection Following
Total Hip Arthroplasty
  • ICL 34 35

2
Introduction
  • In the 1960s, Charnley reported a rate of
    infection of 9.5.
  • More recently, authors have reported that
    infection causes failure after 1-2 of primary
    THAs.
  • In the US, the cost per year to treat the
    3,500-4,000 infections following THA is between
    150 and 200 million dollars.

3
Introduction
  • Infection following THA can present a diagnostic
    challenge
  • No test is 100 sensitive and 100 specific.
  • The diagnosis then relies heavily upon the
    surgeons judgement of the clinical presentation,
    the findings on PE, and the interpretation of the
    results of previous investigations. Misdiagnosis
    can be critical.

4
Clinical Presentation
  • A thorough HP are of paramount importance in the
    Dx of infection.
  • Coventry and later Fitzgerald and assoc.
    described the most common system for the
    classification of infection after THA.
  • Type-I
  • Type-II
  • Type-III

5
Type-I Infections
  • These occur immediately in the postop
    period--usually during the first month.
  • Systemic signs include fever, chills, sweating,
    and continuous pain.
  • Wound appears erythematous, swollen, fluctuant,
    and tender, and if drainage is present it is
    usually purulent.
  • Caused by infected hematomas or superficial
    wounds spreading below the fascia.

6
Type-II Infections
  • These are also believed to begin at the time of
    surgery.
  • Usually seen between 6 and 24 months after
    procedure
  • Hallmark is a gradual deterioration in function
    and an increase in pain.
  • Often, the only clue to infection is early
    loosening of the components.
  • Systemic Sxs are not part of the presentation.

7
Type-III Infections
  • These are the least common and are caused by a
    hematogenous spread to a previously asymptomatic
    hip, usually 2 years or more after arthroplasty.
  • Generally, there is an acute febrile episode
    followed by a sudden , rapid deterioration of the
    hip.
  • Dx can usually be made on the basis of the HP.

8
Type-III Infections
  • These are likely to occur in patients who are
    immunosuppressed, have recurrent bacteremia, such
    as IVDAs, or those who need repeat urinary
    catheterization.
  • Other factors with type-III are dental
    manipulation, respiratory infections, open skin
    lesions, and endoscopy.

9
Preoperative Investigations
  • White Blood-Cell Count
  • Erythrocyte Sedimentation Rate
  • C-Reactive Protein Level
  • Plain Radiography
  • Radionuclide imaging
  • Other Imaging Modalities
  • Hip Joint Aspiration
  • Molecular Analysis

10
White Blood-Cell Count
  • WBC is rarely abnormal in patients who have
    infection following THA--studies show
    approximately 15.
  • If the patient does have an abnormal count, the
    systemic infection is usually clinically obvious
    and is either type-I or type-III.

11
Erythrocyte Sedimentation Rate and C-Reactive
Protein Level
  • The ESR and the CRP level are the most useful
    screening labs for the diagnosis of a potential
    infection following THA.
  • RBCs have negative charges and acute phase
    reactants have positive charges.
  • An elevated ESR is an indirect indicator of an
    abundance of acute-phase reactants.
  • Values of gt 30 or 35 mm /hour are generally
    considered to be abnormal.

12
C-Reative Protein Levels
  • Synthesized in the liver and is found only in
    trace amounts under normal conditions.
  • It rises in a nonspecific manner as a result of
    infectious, inflammatory, or neoplastic
    disorders.
  • It reaches its maximum values within 48 hours
    after surgery, then returns to trace amounts in
    aprox. 2-3 weeks. Therefore, it is a more
    sensitive indicator of infection.

13
Plain Radiography
  • Plain radiographs should be made for all patients
    who have a failed arthroplasty, even though they
    are of limited value as an investigative tool for
    the dx of infection.
  • Many radiographic findings are found in both
    septic and aseptic failure.
  • Periosteal new bone formation, with/without
    loosening of a component, has been considered
    pathognomonic of deep infection.

14
Plain Radiography
  • Early loosening and rapidly progressive
    radiolucent lines are also suggestive of
    infection.
  • Evidence of loosening of the femoral component
    involves radiolucency along the stem-cement
    interface, fracture of the cement mantle or the
    stem, or migration of the prosthesis.

15
Plain Radiography
  • Acetabular loosening is indicated by migration of
    the socket or the cement mantle, protrusio
    acetabuli, or acetabular fracture.
  • Athrography can improve the accuracy in
    diagnosing loosening especially on the acetabular
    side.

16
Radionuclide Imaging
  • Technetium-99m bone scans are sensitive but not
    specific.
  • A negative bone scan can rule out infection.
  • Many conditions can result in increased uptake
    for as long as one year after an uncomplicated
    THA and as long as 2 years after insertion of a
    prosthesis without cement.

17
Radionuclide Imaging
  • Gallium-67 citrate is an isotope that accumulates
    in areas of inflammation.
  • It is also non-specific as any process resulting
    in reactive bone formation may cause increased
    uptake.
  • Indium-111-labeled white blood cells are useful
    for the dx of conditions of increased vascularity
    and white blood-cell uptake. This has been used
    in combination with technetium and had higher
    sensitivities and specificities.

18
Radionuclide Imaging
  • Radiolabeled immunoglobulin-G has been used for
    the investigation of musculoskeletal infections.
  • One advantage is that the patient does not have
    to have phlebotomy before the scan is made.
  • Until additional studies are performed, the
    routine use of In-IgG scans cannot be recommended.

19
Radionuclide Imaging
  • Currently, the use of sequential Tc-99 and
    In-111-WBC scans is being recommended, however,
    the use of radiolabeled IgG may supersede the use
    of sequential scans provided they prove to be
    superior for the dx of infection in THA.

20
Other Imaging Modalities
  • MRI can be of value after an infection has been
    diagnosed . MRI can be used to determine the
    extent of the cement mantle within the femur and
    the pelvis so that the revision procedure can be
    planned appropriately.
  • Ultrasound can be used to measure the thickness
    of the joint capsule, which indicates infection.
    Also soft -tissue abscesses can be evaluated.

21
Hip Joint Aspiration
  • This is perhaps the most useful investigative
    tool for definitive confirmation of the presence
    or absence of infection.
  • Now most authors favor a more limited role, with
    aspiration being used to confirm a clinical
    suspicion of infection.
  • It can also support or negate the findings of
    other labs such as ESR and CRP that may be
    falsely elevated in connective-tissue dx.

22
Aspiration
  • An additional benefit is the ability to identify
    the organism and its antibiotic-sensitivity
    profile, which may influence preoperative
    planning.
  • The reported rates of sensitivity and specificity
    have varied widely. This suggests that
    aspiration is better for ruling infection in than
    for ruling it out.
  • All ABX should be discontinued for 2-3 weeks
    before the aspiration.

23
Aspiration
  • Local anesthetics should be used only for the
    skin and not in the joint as they are
    bacteriostatic.
  • Three samples are taken and if all three are
    positive a dx of infection is made.

24
Intraoperative Investigations
  • Intraoperative Frozen Sections--if ten or greater
    PMNs are found in the high-power field, this is
    evidence of a probable infection.
  • Gram Stain--these may be specific, but it lacks
    any acceptable level of sensitivity.

25
Intraoperative Cultures
  • Preoperative Abx should be withheld until
    specimens have been obtained
  • Clean instruments that have not been used on the
    skin should be used to obtain the specimens.
  • Samples should be taken close to the prosthesis
    and from inflamed tissue.
  • A minimum of three tissue specimens should be
    sent fresh for immediate processing.

26
Molecular Analysis
  • Molecular technology may be used to diagnose the
    presence of bacterial DNA and RNA.
  • Polymerase Chain Reaction (PCR) enables to
    production of large amounts of specific sequences
    of target DNA from small quantities of starting
    material.
  • It is susceptible to contamination because of its
    extremely high sensitivity to any bacterial
    particles.

27
Protocol for the DX of Infection
  • Following a careful HP, both the ESR and CRP
    level should be determined.
  • If both results are normal and there is no
    suggestion of infection clinically, no additional
    investigations are needed.
  • If the ESR or CRP level is elevated for any
    reason or there is clinical suspicion of
    infection, then an aspiration of the hip joint
    should be performed.

28
Protocol--continued
  • A dx is made if the clinical suspicion in high
    the ESR or the CRP level, or both, are elevated
    for no other known reason and the cultures of
    the aspirated fluid are positive.
  • If the ESR or the CRP level, or both, are falsely
    elevated, an intraoperative frozen section may be
    used to confirm the dx.
  • A sequential indium bone scan may be used
    preoperatively if the frozen section will not be
    available.

29
Conclusion
  • The single most important factor in determining
    the treatment options for a patient in whom a THA
    has failed is the exclusion of a dx of infection.

30
Treatment of Infection at the Site of THA
  • It is estimated that 200,000 THA will be
    performed this year in the US and that more than
    4,000 new cases of periprosthetic hip infections
    will need treatment.
  • There are considerable financial implications
    also involved in revision THA.
  • A longer stay in the hospital, longer OR time,
    greater blood loss, higher rate of complications,
    as well as a higher cost of the implants. It is
    estimated that the cost of tx of an infected THA
    is 50,000.

31
Surgical Treatment Options for Infected Total Hip
Prosthesis
  • Debridement with retention of the prosthesis
  • An immediate one-stage exchange arthroplasty
  • An excision arthroplasty-either as a definitive,
    permanent procedure or as the first of a two or
    even three-stage reconstructive procedure.

32
Antibiotic Usage
  • Antibiotics may be used as an adjunct to surgery
    either systemically or locally ( with the use of
    bone cement as the vehicle), or both.
  • They may be used either to eradicate the
    infection or to chronically suppress the
    infection without surgical intervention.

33
Microbiologic Considerations
  • Staphylococcus aureus and Staphylococcus
    epidermidis are the most common infecting
    organisms. These are followed by a wide range of
    gram- positive and gram negative bacteria.
  • More than 95 of the S aureus are sensitive to
    oxacillin and therefore a cephalosporin, however,
    S epidermidis has up to a 30 resistance to
    oxacillin.

34
Micro Considerations
  • Recent attention has been focused on the ability
    of an infecting organism to produce a slime
    layer, or glycocalyx. This layer takes time to
    form.
  • Bacteria that exist within this biofilm are at
    least 500 times more resistant to antibiotics
    than the planktonic forms. They are also
    resistant to complement activation and neutrophil
    injestion.

35
Surgical Considerations in Revisions
  • 1. Old healed incisions should be used to gain
    access to the hip provided that the surgical
    exposure is not compromised.
  • 2. Antibiotics should be withheld until the
    hip-joint capsule has been incised and specimens
    have been obtained.

36
  • 3. The choice of surgical approach should be
    based on the need to remove all foreign material
    and dead tissue, including bone, while at the
    same time avoiding devascularization of the
    tissue.
  • 4. When all necrotic tissue and foreign material
    have been removed, the wound should be copiously
    irrigated with saline solution.

37
Treatment Protocols
  • Antibiotics Without Surgery
  • Debridement with Retention of the Prosthesis
  • Girdlestone Arthroplasty
  • Single-Stage Exchange Arthroplasty
  • Two-Stage Exchange Arthroplasty

38
Antibiotics without Surgery
  • Most commonly used in the form of suppressive
    therapy when the patient is unfit to undergo
    major surgery or simply refuses further surgical
    treatment.
  • The infecting organism must be known as well as
    the sensitivity and MIC.
  • The antibiotic must be well tolerated by the
    patient or noncompliance will result.

39
Debridement with Retention of the Prosthesis
  • There is little argument about the necessity to
    remove a loose prosthesis from a chronically
    infected joint, however, removal of a well-fixed
    total hip implant carries the risk of causing
    major damage to the remaining bone stock.
  • Tsukayama and associates emphasized the
    importance of limiting this tx to infections that
    developed less than 1 month postop.

40
  • This did not allow the organisms to produce the
    resistant slime layer and could therefore be
    controlled.
  • The primary difficulty appears to be the lack of
    accuracy with which acute infections can be
    distinguished from chronic ones.
  • This procedure can only be implemented if the
    history of the infection can be accurately
    identified.

41
Girdlestone Arthroplasty
  • The general consensus is that the procedure is
    highly effective in controlling infection and
    reducing pain however, it usually is associated
    with a considerable loss of function. Patients
    walk poorly and almost always need walking aids.
  • Limb shortening may range from 3-11cm but most
    typically ranges from 4-6 cm.

42
  • This may be appropriate for patients who are
    mentally impaired and who are unable to cooperate
    with the postoperative restrictions.
  • Excision arthroplasty is the treatment of choice
    for patients who have an infection and a history
    of intravenous drug abuse.

43
Single-Stage Arthroplasty
  • The major advantage of a single-stage exchange
    procedure is the avoidance of additional surgical
    procedures , especially those with medical
    problems that the risks of additional surgeries
    are too high.
  • The potential benefits must be weighed against
    the slightly lower rates of eradication of
    infection when compared to the two-stage
    procedures.

44
  • Furthermore, the insertion of implant with cement
    is not appropriate in many revision procedures,
    particular when bone stock is deficient.

45
Two-Stage Exchange Arthroplasty
  • In North America, periprosthetic infection of the
    hip are most commonly treated with a two-stage
    procedure.
  • The principles of the two-stage procedure is to
    remove the implant as well as all of the cement,
    and the necrotic tissue. Then to undergo
    prolonged IV antibiotics, and then to eventually
    reimplant a new prosthesis.

46
  • Most protocols have included 6 weeks of
    intravenous antibiotics. There is some evidence
    that the use of IV Abx for less than 4 weeks is
    associated with a higher rate of recurrence when
    the infection is caused by a more virulent
    organism.
  • Lieberman and assoc. reported that
    reimplantation after 6 weeks of tx did not differ
    than those patients who were reimplanted after 1
    year.

47
The Authors Protocol
  • They use the prosthesis of antibiotic-loaded
    acrylic cement (PROSTALAC), 4-6 weeks of
    antibiotic tx, followed by repeat aspiration of
    the joint at a minimum of 4 weeks after
    discontinuation of the Abx.
  • They then proceed with reimplantation if the
    culture is negative and the clinical appearance,
    ESR and CRP level are indicative of resolution of
    infection.

48
Other Surgical Options
  • Arthrodesis of the hip should be reserved for
    young, males who have strenuous functional
    demands.
  • These usually function well but develop a
    limb-length discrepancy mean of 4.6 cm.

49
Conclusion
  • It is necessary to carefully evaluate each
    patient with a periprosthetic infection. First,
    to best determine what stage infection is
    present, then to customize an appropriate
    treatment plan that will first and foremost
    control the infection, then provide the patient
    with best possible functional outcome without
    jeopardizing the patients health and well-being.
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