Updated: 12/11/2022

Prosthetic Joint Infection

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  • summary
    • Prosthetic Joint Infections are serious complications of hip and knee arthroplasty and a common cause for revision arthroplasty.
    • Diagnosis is multifaceted with elevated inflammatory markers, radiographic changes around the prosthesis and aspiration results all assisting with diagnosis.
    • Treatment generally involves prolonged IV antibiotics and two-stage revision arthroplasty.
  • Epidemiology
    • incidence
      • primary joint replacement
        • 1-2% TKA vs. 0.3-1.3% THA
      • revision joint replacement
        • 5-6% TKA vs. 3-4% THA
    • risk factors
      • pre-operative
        • active infection
          • local cutaneous, subcutaneous, deep-tissue or joint infection
          • systemic septicemia
        • previous local surgery/prior local infection
      • postoperative
        • immune suppression
          • immunosuppressant drugs
            • anti-TNF agents (e.g. infliximab, etanercept, adalimumab, certolizumab, golimumab)
            • antimetabolites (e.g leflunomide)
            • corticosteroids
          • immunosuppressive conditions (dysplasia or neoplasia)
            • poorly controlled diabetes mellitus (HBA1c >7)
            • chronic renal disease
            • acute liver failure
            • malnutrition (eg. albumin <3.5; total serum leukocytes <800)
            • HIV (CD4 counts <400)
        • inflammatory arthropathy
          • rheumatoid arthritis
          • psoriasis
          • ankylosis spondylitis
        • lifestyle factors
          • morbid obesity
          • smoking
          • excessvice alcohol consumption
          • intravenous drug use
          • poor oral hygiene
  • Etiology
    • Pathophysiology
      • most common bacterial organism include
        • staphylococcus aureus
        • staphylococcus epidermidis
        • Coagulase-negative Staphylococcus (chronic infections)
      • most common fungal pathogen
        • Candida species (e.g. Candida albicans)
    • Prophylaxis
      • screening
        • screen and optimize risk factors
        • nasal mupirocin for decolonization of nasal MSSA/MRSA
        • routine urine cutures NOT warranted pre-operatively, unless history or symptoms of UTI
        • stop DMARDs 4-6 weeks prior to surgery
        • revision joint replacement
          • normalized ESR, CRP off antibiotics
      • operatively
        • pre-operative skin cleansing with antiseptic wash
        • systemic antibiotics
          • administered within 30 minutes to incision, and >10 minutes prior to tourniquet
          • continued for 24 hours after surgery
        • operative room
          • vertical laminar airflow systems
          • limit hospital personal OR traffic in-and-out of room
      • post-operatively
        • antibiotics prior to dental work is dependant on host risk factors
  • Classification
    • Time of onset
      • Acute infection
        • infection within 3-6 weeks from surgery
          • CDC definition < 90 days from date of joint replacement
        • biology
          • usually confined to joint space
          • no invasion into prosthetic-bone interface
          • no biofilm production
        • S. aureus commonly associated with acute THA PJIs
      • Chronic infection
        • infection more than 3-6 weeks from surgery
          • CDC definition > 90 days from date of joint replacement
        • biology
          • biofilm created by all bacteria forms on implant within four weeks
            • composition
              • 15% cells and 85% polysaccharide layer (glycocalyx)
              • glycocalyx allows biofilm to adhere to prosthesis and sealoff infection and protect bacteria from host immune system
            • consequence
              • no method exists to safety remove biofilm and eradication is difficult
              • prosthetic explant indicated with infection >4 weeks due to biofilm
            • infection has invaded prosthetic-bone interface
          • S. epidermidis most common organism in chronic THA PJIs
    • Source of infection
      • Direct invasion
        • sinus tract into joint capsule
        • wound dehiscence
      • Hematogenous infection
        • infection in a longstanding infection-free joint secondary to another infection (eg. dental work, infected gallbladder)
  • Presentation
    • History
      • may have history of the following
        • recent or active bacteremia
        • multiple local surgeries
        • skin/epithelial tissue penetration (eg. IV drug use, colonoscopy, dental work, ulceration, wound complication)
    • Symptoms
      • persistent pain and stiffness at site of arthroplasty is associated with infection in >90% of patients
      • acute onset with swelling, tenderness, and drainage
      • chronic infections show pain and more subtle symptoms
        • function deteriorates over time
        • pain worsens over time
    • Physical exam
      • inspection
        • sinus tract to the joint is a definite infection
        • warmth, redness, or swelling
        • low grade fever
      • motion
        • limited by pain and swelling
  • Imaging
    • Radiographs
      • findings
        • periosteal reaction
        • scattered patches of osteolysis
        • generalized bone resorption without implant wear
        • transcortical sinus tracts
        • implant loosening
    • Bone scan
      • modalitity
        • Tc-99m (technetium) detects inflammation and In-111 (indium) detects leukocytes
        • triple scan can differentiate infection from fracture or bone remodeling
      • indications
        • if infection is suspected, but cannot be confirmed by aspiration or blood work
      • sensitivity and specificity
        • 99% sensitivity and 30% to 40% specificity
    • Positron emission tomography (PET)
      • indication
        • may help to identify areas of high metabolic activity using fluorinated glucose
      • sensitivity and specificity
        • 98% sensitivity and 98% specificity
  • diagnostic criteria
    • 2018 criteria for prosthetic joint infections as defined by Parvizi and associates
      • Derived from 2011 MSIS; 98% sensitivity and 99.5% specificity for diagnosing PJI
      • Major criteria (diagnosis can be made when 1 major criteria exist)
        • sinus tract communicating with prosthesis
        • pathogen isolated by culture from 2 separate tissue/fluid samples from the affected joint
      • Minor criteria (preoperative diagnosis)
        • The below scores are added together to determine:
          • ≥6 = infected; 2-5= inconclusive; 0-1=not infected
        • Serum Labs
          • Elevated CRP (>10mg/L) or D-dimer (>860ng/mL) - 2 points
          • Elevated ESR (>30mm/h) - 1 point
        • Synovial Fluid Analysis
          • Elevated synovial WBC (>3,000 cells/µl) or Leukocyte Esterase - 3 points
          • Positive alpha-defensin - 3 points
            • most sensitive and specific marker for PJI
          • Elevated synovial PMN (>80%) - 2 points
          • Elevated synovial CRP (>6.9mg/L) - 1 point
      • Inconclusive (inconclusive preop score (2-5) or dry aspiration)
        • Positive histology (>5 PMN per hpf in 5 hpf at x400 magnification (intraoperative frozen section of periprostehtic tissue) - 3 points
        • Purulence in affected joint - 3 points
        • Single positive culture - 2 points
        • Preoperative score + intraoperative score combined
          • Combined score â‰¥6 = infected; 4-5= inconclusive; 0-3= not infected
  • Studies
    • Labs
      • Blood panel
        • WBC
          • not specific or sensitive
      • ESR and CRP
        • CRP
          • physiology
            • peaks 2-3 days after surgery
            • returns to normal at 21 days (3 weeks)
          • normal range
            • acute (< 6 weeks from surgery) = <100 mg/L
            • chronic (> 6 weeks from surgery)= <10 mg/L
        • ESR
          • physiology
            • peaks 5-7 days after surgery
            • returns to normal 90 days (3 months)
          • normal range
            • acute (< 6 weeks from surgery) = no consences
            • chronic (> 6 weeks from surgery)= <30 mm/hr
      • Serum interleukin-6 (IL-6, normal <10pg/mL)
        • physiology
          • peaks 8-12h after surgery
          • returns to normal 48-72h after surgery (3 days)
          • less commonly followed, but can monitor and follow the progress of infection
        • outcomes
          • has been shown to have the highest correlation with periprosthetic joint infection
          • sensitivity 100%, specificity 95%
          • false positives
            • RA
            • multiple sclerosis
            • AIDS
            • Paget's disease of bone
    • Joint aspiration
      • indications
        • whenever there is a strong suspicion in order to confirm the diagnosis
      • lab order request
        • cell count and differential
        • crystals
        • gram stain
        • cultures and specificity
      • outcomes
        • cell count and differential
          • lowest serologic values suggestive of infection
            • synovial WBC >3,000 cells/ul and PMN >80% in knees
              • synovial WBC >10,000 cells/ul in the first 6 weeks after TKA suggestive of infection
            • WBC >3,000 cells/ul and PMN >80% for hips
            • WBC >4350 cells/ul and PMN >85% for MoM hips
            • WBC >1166 cells/ul and PMN >64% for hip antibiotic spacers
        • gram stain
          • stain for bacteria in sample
          • specificity > sensitivity
            • positive test would be indicative of infection, however a negative test does not rule out infection
        • repeat aspiration
          • indicated in cases of inconclusive aspirate and peripheral lab data
          • waiting two weeks for a repeat aspiration off antibiotics
      • other tests
        • alpha-defensin immunoassay test
          • peptide released by neutrophils
          • 100% sensitivity and 98% specificity for diagnosis of PJI
          • sensitivity not affected by previous antibiotic administration
        • leukocyte esterase colorimetric strip test
    • Peri-operative analysis
      • microbiology
        • definitive diagnosis can be made if the same organism is obtained by repeat aspirations or at least 3 of 5 periprosthetic specimens obtained at surgery
          • complications
            • false-positive rate is 8%
            • tissue sample better than swabs
      • histology
        • Intraoperative frozen section
          • indications
            • equivocal cases with elevated ESR and CRP or suspicion for infection
            • sensitivity 85% and specificity 90% to 95%
            • >5 PMNs/hpf x 5 hpf is probable for infection
  • Treatment
    • Nonoperative
      • chronic suppressive antibiotic therapy
        • indications
          • unfit for surgery
          • refuse surgery
          • systemic spread and maintain joint motion with symptomatic relief
        • outcomes
          • 10% to 25% success rate of eradication
          • 8% to 21% complication rate
    • Operative
      • polyethylene exchange with component retention, IV abx for 4-6 weeks
        • indications
          • acute infection (<3 weeks after surgery)
          • acute hematogenous infection (weak literature, ideally <48-72hrs from symptom onset)
        • techniques
          • thorough tissue debridement and irrigation with large-volume of irrigant
        • outcomes
          • 50% to 55% success rate
          • implants must be removed if reinfection documented
          • Dependant of bacteria speciation
      • one-stage replacement arthroplasty
        • indications
          • used more commonly in Europe for infected THA
          • no sinus tract, healthy patient and soft tissue, no prolonged antibiotic use, no bone graft
          • low-virulence organism with good antibiotic sensitivity
        • technique
          • use antibiotic-impregnated cement
        • advantages
          • lower cost and convenience with single procedure
          • earlier mobility
        • disadvantages
          • higher risk of continued infection from residual microorganisms
        • outcomes
          • variable success of 75-100%
      • two-stage replacement arthroplasty
        • indications
          • gold standard for an infected joint >4 weeks after arthroplasty
          • must be medically fit for multiple surgeries
          • requires adequate bone stock
          • requires confirmation of microbial eradication
            • benign clinical exam
            • normal labs (WBC, ESR, and CRP)
            • negative aspiration cultures
              • obtain repeat cultures at least two weeks after planned antibiotic course has been completed
        • techniques (see section below)
          • prosthesis removal, antibiotic spacer, IV antibiotics for 4-6 weeks and delayed reconstruction
        • outcomes
          • bilateral TKA resection arthroplasty followed by 6 weeks of antibiotics and bilateral reimplantation has excellent results at 2-year follow-up
          • early reimplantation within 2 weeks has 35% success rate
          • delayed reimplantation >6 weeks has a 70-90% success rate
          • cementless reimplantation in the hip has better outcomes than cemented
      • resection arthroplasty
        • indications
          • poor bone and soft tissue quality
          • recurrent infections with multi-drug resistant organisms
          • medically unfit for multiple surgeries
          • failure of multiple previous reimplantations
          • elderly nonambulatory patients
        • disadvantages
          • short limb, poor function, and patient dissatisfaction
        • technique
          • remove all infected tissue and components with no subsequent reimplantation
        • outcomes
          • total knee success rate is 50% to 89%
          • total hip success rate is 60% to 100%
      • arthrodesis
        • indications
          • reimplantation is not feasible due to poor bone stock
          • recurrent infections with virulent organisms
        • outcomes
          • 71% to 95% success rate with bony fusion and infection eradication
      • amputation
        • indications
          • total knee infections recalcitrant to other options
          • severe pain, soft tissue compromise, severe bone loss, or vascular damaged
        • technique
          • AKA
  • Techniques
    • Surgical debridement and polyethylene exchange
      • debridement
        • modular parts should be removed to remove fibrin layer between plastic and metal parts which acts as a nidus of infection
      • polyethylene exchange
        • be sure component available
    • Two-stage replacement arthroplasty
      • prosthetic explant
      • surgical debridement
        • must debride bone implant interface and soft tissues
      • antibiotic spacer and IV antibiotics
        • advantages of spacers
          • reduce joint dead space, provide stabilty, and deliver high dose antibiotics
        • disadvantages of spacers
          • potential local or systemic allergic reactions
          • increased chance of developing antibiotic-resistant organisms
          • only heat-stable antibiotics can be added to cement
        • static or dynamic (articulating) spacers can be used
        • advantages of static spacers
          • allow delivery of higher doses of antibiotics (not premade)
          • better wound healing (no joint motion)
        • advantages of articulating spacers
          • decreased reimplantation exposure time
          • better maintenance of joint space and motion
          • decreased quad shortening
          • better patient satisfaction
          • both spacer types have equivalent functional outcomes and rate of infection recurrence
        • spacer antibiotics
          • each 40 g bag of cement should have 3 g of vancomycin and 4 g of tobramycin added
            • gentamycin may be substituted for tobramycin
          • elution of antibiotics depends on cement porosity, surface area (beads increase area), and antibiotic concentration
          • must use heat stable antibiotics (vancomycin, tobramycin, gentamicin)
        • IV antibiotics
          • wait to administer intraoperatively until aspiration and cultures taken
          • must be administered for 4 to 6 weeks after explant
          • initial empiric regimen
            • first-generation cephalosporin
            • vancomycin (if any of the following are true)
              • true allergic sensitivity to penicillin
              • prior history of or documented exposure to MRSA
              • unidentified organism
            • fluconazole
              • prefered for antifungal infections
                • similar efficiacy with IV and oral formulations
          • tailor the regimen based on microorganism and susceptibility testing
      • reimplantation
        • send tissue specimens for culture and frozen section pathology
        • implant only if all preoperative and intraoperative measures are acceptable
        • if intraoperative frozen section demonstrate acute inflammation, debride the wound, reapply cement spacer, and return later
        • when using cement, use antibiotic-impregnated cement
  • Local Antibiotics
    • Properties
      • active against the organism
      • can be incorporated into delivery vehicle (PMMA)
      • thermo stable (will not denature during exothermic polymerisation reaction)
    • Choices
      • aminoglycosides (gentimicin, tobramycin)
        • effective against gram-negative bacilli
        • synergistic against gram-positive cocci (Staphylococcus, Enterococcus)
        • low risk of systemic toxicity
      • Vancomycin
        • effective against gram-positive cocci
        • excellent elution properties
    • Doses
      • low dose = 2g antibiotics:40g of cement
        • commercial antibiotic cement is low dose
          • Cobalt G-HV (Biomet)
          • Palacos R+G (Zimmer)
          • Simplex P (Stryker)
          • Cemex Genta (Exactech)
          • SmartSet GMV (Depuy)
          • VersaBone AB (Smith & Nephew)
      • high dose ≥ 3.6g antibiotics:40g of cement
        • highest doses without systemic toxicity
          • 12.5g tobramycin:40g cement
          • 10.5 vancomycin:40g cement
      • practical dose
        • vancomycin is 1g per vial, tobramycin is 1.2g per vial
        • use 3g vanco and/or 3.6g tobramycin in 40g cement
          • use extra liquid monomer (1.5-2 ampoules monomer : 1 bag cement)
    • Elution properties
      • rapid release in initial 24h
      • followed by rapidly decline in release rate
        • combination dosing (both tobramycin+vancomycin) increases release rate of antibiotics (more than if each were used alone)
      • low levels at 5 weeks
      • experimental models do NOT show difference in elution/concentrations in conventional wound closure vs negative-pressure wound therapy (NPWT)
    • Mixing
      • vacuum mixing
        • removes air bubbles
        • enhances mechanical properties
        • may increase/decrease antibiotic elution rates
      • hand mixing
        • may lead to uneven distribution of antibiotics within cement and inconsistent release
      • sequence of ingredients
        • adding vancomycin powder after cement powder + liquid monomer mixed for 30s results in greater elution
    • Newer techniques
      • vancomycin powder directly into wounds (mostly in spine literature)
      • antibiotic cement coated IM nails
      • local antibiotics bonded to implant surface
  • Complications
    • Failure to eradicate infection
      • poorer prognosis for 2-stage revision for methicillin-resistant organisms
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(OBQ18.123) A 63-year-old patient with a previous right TKA 4 years ago presents with worsening pain in the right knee. The patient reports that pain is worsened when starting physical activity, but is also present at night. Two weeks prior to presentation the patient was given a 1-week course of oral antibiotics for cellulitis affecting the right knee. Serum labs were significant for a CRP of 11 mg/L and an ESR of 35 mm/hr. Synovial fluid analysis revealed 1,000/µL nucleated cells with 85% PMNs and no evidence of crystals. Synovial cultures were negative for any bacterial or fungal growth. Synovial alpha-defensin is positive. Figures A and B are the AP and lateral radiographs of the right knee. The patient opts to undergo a revision total knee arthroplasty. What is the best management at this point?

QID: 213019
FIGURES:

Femoral component revision

1%

(24/2509)

Tibial component revision

1%

(24/2509)

Polyethylene component revision

5%

(113/2509)

One-stage revision of both the femoral and tibial components

7%

(164/2509)

Two-stage revision of both the femoral and tibial components

86%

(2158/2509)

L 1 A

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(OBQ18.245) A 70-year-old man presents with chronic persistent right knee pain and erythema which has been present for 7 weeks after having undergone total knee arthroplasty (TKA) 7 years ago. He is referred after completing a course of oral antibiotics prescribed by his primary care physician, which did not improve his symptoms. His current radiograph is shown in Figure A. Laboratory testing reveals a serum C-reactive protein (CRP) of 50mg/L and an erythrocyte sedimentation rate (ESR) of 67 mm/h. Arthrocentesis is performed and reveals a synovial WBC of 1,500 WBC/uL, with 85% polymorphonuclear cells (PMNs), and negative final cultures. The alpha-defensin test is positive. What is the next best step?

QID: 213141
FIGURES:

Repeat knee arthrocentesis after 2-week antibiotic holiday

10%

(227/2206)

Revision of femoral component without antibiotic therapy

0%

(11/2206)

One-stage revision arthroplasty with intravenous antibiotic therapy for 4-6 weeks

3%

(59/2206)

Two-stage revision arthroplasty with intravenous antibiotic therapy for 4-6 weeks

86%

(1894/2206)

Revision of tibial component without antibiotic therapy

0%

(3/2206)

L 1 A

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(OBQ18.127) A 62-year-old patient that underwent a right hip resurfacing arthroplasty 3 years ago develops worsening right hip pain over the past 6 months. The pain is present at all times, including at night. The patient does not walk with a Trendelenburg gait and does not have reproducible pain on hip examination. Laboratory inflammatory markers from 1 week ago were erythrocyte sedimentation rate of 66 mm/hr (reference <20 mm/hr), C-reactive protein of 22 mg/dL (reference <2.5 mg/dL), cobalt 0.5 µg/L (reference <0.7 µg/L), and chromium of 0.4 µg/L (reference <0.4 µg/L). Figure A demonstrates an AP radiograph of the pelvis. What is the next best step in management?

QID: 213023
FIGURES:

Physical therapy

1%

(12/2363)

Routine follow-up

0%

(5/2363)

Arthrocentesis with synovial fluid analysis

84%

(1975/2363)

2-stage revision

5%

(112/2363)

Metal artifact reduction sequence MRI

10%

(234/2363)

N/A A

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(OBQ18.122) A 66-year-old patient that underwent a right total knee arthroplasty approximately 4 years ago presents with worsening right knee pain over the last 48 hours. The patient has a history of rheumatoid arthritis and recently underwent a dental procedure a week ago. Labs were significant for CRP of 212, ESR 105, and a WBC count of 11K. Aspiration yielded a milky-looking fluid with 55K nucleated cells with 97% PMN. Radiographs are shown in Figures A and B. What is the next best step?

QID: 213018
FIGURES:

Surgical intervention after cultures finalize

4%

(69/1832)

Repeat aspiration of the knee and send for alpha-defensin

3%

(52/1832)

Begin IV antibiotics and re-evaluate in 24-48 hours

2%

(33/1832)

Proceed with surgical intervention now

90%

(1644/1832)

IR guided drain placement

0%

(1/1832)

N/A A

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(OBQ18.64) A 68-year-old patient with diabetes progressively worsening left knee pain of 6 months duration. They underwent a left total knee arthroplasty 7 years ago. Figures A-B demonstrate the current radiographs. Aspiration of the left knee demonstrated 11,500 WBCs and 94% neutrophils. Aspiration cultures grew methicillin-resistant Staphylococcus aureus. What would be the best treatment approach for this patient?

QID: 212960
FIGURES:

Knee arthrodesis

0%

(5/2227)

Long-term antibiotic suppression

0%

(5/2227)

One-stage revision arthroplasty

0%

(10/2227)

Two-stage revision arthroplasty

98%

(2183/2227)

Above knee amputation

0%

(1/2227)

L 1 A

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(SBQ18BS.1) When investigating a periprosthetic hip or knee joint infection, which marker is most sensitive and specific for infection?

QID: 211112

Alpha-defensin

65%

(1593/2446)

Intraoperative frozen section

10%

(247/2446)

Serum interleukin-6 (IL-6)

9%

(219/2446)

C-reactive protein (CRP)

13%

(314/2446)

Leukocyte esterase (LE) colorimetric strip test

2%

(59/2446)

L 3 A

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(OBQ14.50.1) A 62-year-old woman presents to your clinic with knee pain and swelling 4 months after a primary TKA. Her initial recovery was uneventful, but she had a small pustule develop 6 weeks after surgery. An emergency room physician gave her 10 days of oral antibiotics for a "suture abscess" at that time. Since the ED visit, she notes worsening pain and persistent drainage. Figurs A represents a clinical photo from today's appointment. What is the next best step in management?

QID: 212435
FIGURES:

Admit directly from clinic for I&D and polyethylene exchange

21%

(509/2391)

Prescribe oral antibiotics and follow up in 2 weeks

0%

(10/2391)

Aspirate the patient's knee and plan for surgery

77%

(1843/2391)

Prescribe home health wound care

0%

(5/2391)

Placement of a knee immobilizer and hold physical therapy for 2 weeks

0%

(2/2391)

L 3 A

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(SBQ13HK.45.1) Which of the following most accurately lists the relative risk of periprosthetic joint infection (PJI) in total joint arthroplasty in order from lowest to highest risk?

QID: 212341

Primary hip < primary knee < revision knee < revision hip

7%

(176/2564)

Primary hip < primary knee < revision hip < revision knee

76%

(1940/2564)

Primary hip < revision hip < primary knee < revision knee

5%

(123/2564)

Primary knee < revision knee < primary hip < revision hip

2%

(64/2564)

Primary knee < primary hip < revision knee < revision hip

9%

(242/2564)

L 4 C

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(SBQ13HK.68.1) A 64-year-old male is 6 months out from left total knee arthroplasty. He has had at least two months of pain and swelling to the operative joint. In your initial workup, he is found to have a well-healed surgical incision, a serum CRP of 13mg/L and an ESR of 19mm/h. You perform arthrocentesis, which results in a negative alpha-defensin, synovial WBC of 1000 cells/µL, synovial PMNs of 90%, and synovial CRP of 4mg/L. What is the next best step in management?

QID: 214225

Corticosteroid injection

12%

(233/1910)

Proceed to OR for histologic examination

44%

(832/1910)

Proceed with two stage revision

27%

(521/1910)

Proceed with single stage polyethylene exchange with irrigation and debridement

13%

(241/1910)

6 weeks of IV antibiotics

4%

(72/1910)

L 5 B

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(OBQ13.234) A 60-year-old male with history of renal transplantation and previous intravenous drug abuse undergoes total knee arthroplasty. Two years later, he begins to have mild knee pain and low-grade swelling that persists for 10 months before he finally comes to the emergency room. Examination reveals no fever. Range of motion is 5 to 70 degrees. Erythrocyte sedimentation rate is 22mm/h, and C-reactive protein is 0.8mg/L. Knee aspiration reveals 12,000/mm3 nucleated cells with 76% neutrophils. Gram stain is negative and aerobic and anaerobic cultures are negative after 4 days in culture. His symptoms do not resolve after 5 days of empiric intravenous antibiotics and he is taken to the operating room for arthroscopic irrigation and debridement. Operative synovial tissue cultures are shown in Figure A. What is the best next step?

QID: 4869
FIGURES:

Cessation of immunosuppressant medication, lifelong antimycobacterial suppression

1%

(31/3954)

Open irrigation and debridement, implant retention and lifelong antifungal suppression

3%

(131/3954)

Open irrigation and debridement, resection arthroplasty, antimycobacterial drugs for 6 to 12 months

9%

(365/3954)

Open irrigation and debridement, single-stage exchange, antifungal drugs for 6 to 12 months

3%

(101/3954)

Open irrigation and debridement, two-stage exchange, antifungal drugs for 6 to 12 months

83%

(3283/3954)

L 2 C

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(OBQ12.263) Increasing the porosity of a cement spacer for an infected total knee arthroplasty leads to which of the following?

QID: 4623

Increased strength

1%

(33/4091)

Increased elution of antibiotics

90%

(3691/4091)

Increased cement density

1%

(32/4091)

Improved cement-prosthesis bonding

5%

(186/4091)

Increased reinfection rate

3%

(133/4091)

L 1 B

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(OBQ11.46) A 68-year-old woman underwent a right total knee arthroplasty 5 years ago and has increasing right knee pain over the past 2 months. Radiographs are seen in Figures A and B, respectively. Laboratory studies demonstrate a C-reactive protein of 10 mg/dL (normal < 2.0 mg/dL) and an erythrocyte sedimentation rate of 50 mm/h (normal < 20 mm/h). Knee aspiration shows white blood cell count of 3,400/mm3 with 90% polynuclear cells. The patient's gram stain and cultures are negative. What is the most appropriate next step in management?

QID: 3469
FIGURES:

Irrigation and debridement with polyethylene spacer exchange

5%

(208/4352)

One-stage revision

1%

(65/4352)

Two-stage revision

90%

(3929/4352)

One-stage revision with antibiotic impregnated cement

2%

(99/4352)

One-stage revision with direct antibiotic infusion into knee joint via hickman catheter

0%

(20/4352)

L 1 A

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(OBQ11.195) A 50-year-old woman underwent cemented total knee arthroplasty 3 weeks ago. She reports that she has 1 week of drainage the size of a quarter on a gauze pad that she places over the incision three times daily. Her body mass index is 53 and her medical problems include hypertension and type 2 diabetes. Blood work shows a CRP of 1.1mg/L (normal 1-3mg/L). Knee aspiration yields WBC of 673 cells/mm(3) with 30% polymorphonucleocytes, and a negative gram stain. There is no surrounding erythema but there is a 1cm area at the inferior aspect of the wound that has a large amount of serous drainage able to be expressed. She has a painless range of motion is 0° to 117°. What would be the next most appropriate step in management?

QID: 3618

Removal of all components with antibiotic spacer placement and staged revision

3%

(96/3393)

One-stage irrigation and debridement with removal of components to a cementless prosthesis

1%

(27/3393)

Empiric oral antibiotics for 4 weeks and steri-strips over the area of drainage

12%

(398/3393)

Surgical exploration with debridement and possible polyethylene exchange

82%

(2774/3393)

Bone scan and repeat aspiration with empiric intravenous antibiotics for 4 weeks

3%

(86/3393)

L 2 C

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(OBQ11.60) A 72-year-old man reports persistent, progressively worsening pain in his hip after undergoing a total hip arthroplasty 15 months ago. A current AP hip radiograph is shown in Figure A. What is the next most appropriate step in the care of this patient?

QID: 3483
FIGURES:

IV Antibiotics

0%

(8/3399)

Obtain serum metal ion values

1%

(32/3399)

Obtain ESR, CRP, and WBC

95%

(3240/3399)

Obtain CT and MRI of the hip

1%

(44/3399)

Urgent debridement and component explantation

2%

(61/3399)

L 1 B

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(OBQ10.54) A 64-year-old female underwent a total knee arthroplasty 4 years ago and has increasing pain for the past 6 months. Knee aspiration reveals 4,000 leukocytes with 80% polymorphonucleocytes and a 2-stage revision arthroplasty is planned. When comparing articulating cement spacers to static spacers following resection, all of the following are potential advantages of articulating spacers EXCEPT

QID: 3142

Decreased quadriceps shortening

1%

(41/3478)

Decreased rate of infection recurrence

84%

(2924/3478)

Increased knee range of motion for duration of cement spacer implantation

4%

(155/3478)

Better maintenance of joint space

2%

(81/3478)

Decreased exposure time during reimplantation

7%

(258/3478)

L 2 C

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(OBQ10.147) A 65-year-old woman complains of worsening left knee pain 7 months following total knee arthroplasty. She reports good pain relief for the initial 5 months following surgery. Physical exam is notable for a stable knee with range of motion from 0-115 degrees. Radiographs are provided in Figures A and B. Which of the following is the most appropriate next step in management?

QID: 3235
FIGURES:

Nuclear bone scan

1%

(19/3263)

One stage revision total knee arthroplasty

1%

(17/3263)

Knee MRI

1%

(20/3263)

CRP, ESR, WBC

96%

(3124/3263)

Physical therapy with focus on range of motion and quadriceps strengthening

2%

(63/3263)

L 1 C

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(OBQ09.45) A 65-year-old male presents with a painful right total knee arthroplasty, which was performed ten years ago. CRP is 15 mg/L. Knee aspiration reveals a purulent fluid with 3,100 WBC's with 83% PMN's. Culture results are pending. Which of the following is the best management option?

QID: 2858

Physical therapy, ice, and follow-up evaluation in 2 weeks

4%

(123/3275)

Repeat aspiration if cultures are positive

9%

(291/3275)

Oral antibiotics

0%

(10/3275)

Intravenous antibiotics

4%

(115/3275)

Surgical explant of components

83%

(2725/3275)

L 3 A

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(SAE07HK.92) A 68-year-old man with no significant medical history underwent a total knee arthroplasty 4 years ago. A radiograph is shown in Figure 55. He reports that he had no problems with the knee until 6 weeks ago when he noted the gradual onset of pain following a colonoscopy. Examination reveals a painful, swollen knee. Knee aspiration reveals a WBC count of 40,000/mm3. Management should consist of

QID: 6052
FIGURES:

suppressive antibiotics.

1%

(11/864)

open irrigation and debridement with polyethylene exchange.

4%

(32/864)

one-stage resection arthroplasty and reimplantation.

3%

(22/864)

two-stage resection arthroplasty and reimplantation.

91%

(787/864)

arthroscopic irrigation and debridement.

0%

(2/864)

L 1 E

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(SAE07HK.14) Antibiotic-loaded bone cement prostheses, such as that shown in Figure 8, are best created by using which of the following methods?

QID: 5974
FIGURES:

Using commercially available antibiotic-loaded bone cement

4%

(41/922)

Adding 0.5 g vancomycin to commercially available antibiotic-loaded bone cement

4%

(38/922)

Adding 0.5 g tobramycin and 0.5 g vancomycin/unit of standard bone cement

8%

(77/922)

Adding either 1.0 g vancomycin or 1.2 g tobramycin per 40 g of standard bone cement

36%

(336/922)

Adding a minimum of 3.6 g tobramycin and 1.0 g vancomycin per 40 g of bone cement

46%

(424/922)

L 5 E

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(OBQ06.184) Which of the following total hip arthroplasty patients appropriately meets the criteria for a surgical debridement with isolated femoral head and polyethylene liner exchange?

QID: 370

Prosthesis infection of 4 months duration

1%

(31/3645)

Prosthesis infection 8 weeks following implantation

13%

(474/3645)

Prosthesis infection 3 days following a systemic infection

83%

(3012/3645)

Acetabular component loosening due to osteolysis

2%

(81/3645)

Vancouver Type A periprosthetic fracture.

1%

(33/3645)

L 2 D

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(OBQ05.165) A 64-year-old woman with osteoarthritis underwent bilateral total knee replacement 3 years ago. Current radiographs are shown in Figure A. She reports a 3-month history of bilateral knee pain while at rest and increasing swelling in the knees. Her ESR and CRP are elevated and bilateral knee aspiration cultures reveal Staphylococcus aureus. What is the most likely outcome if the patient undergoes simultaneous, bilateral knee resection arthroplasty with cement spacer and a course of intravenous antibiotics?

QID: 1051
FIGURES:

Prosthesis reimplantation with need for multiple surgical debridements at 2-year follow-up

5%

(87/1807)

20% risk of above knee amputation

5%

(87/1807)

Retention of antibiotic cement spacer and low chance of successful prosthesis reimplantation at 2-year follow-up

10%

(187/1807)

50% rate of conversion to knee fusion following resection arthroplasty

5%

(87/1807)

Successful prosthesis reimplantation at 2-year follow-up with less than 20% revision rate

75%

(1350/1807)

L 2 D

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(OBQ05.176) A 72-year-old male presents 2 years status post fixation of an impending pathologic right femur fracture due to metastatic renal cell carcinoma. He is minimally ambulatory due to pain. Despite radiation therapy, there has been progression of the lesion with extensive cortical bone loss, which is shown in Figure A. A proximal femoral replacement arthroplasty is performed without complications, and is demonstrated in Figure B. Which of the following is true regarding this patients post-operative course?

QID: 1062
FIGURES:

Deep prosthetic infection is the most common complication

52%

(859/1642)

Mean Harris Hip score will likely not improve

5%

(87/1642)

The patient will most likely continue to be minimally ambulatory

25%

(404/1642)

Aseptic failure rate at 5 years is >50%

15%

(249/1642)

Pre-operative radiation decreases the risk of infection post-operatively

2%

(29/1642)

L 4 D

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(OBQ05.235) A 67-year-old diabetic male presents 4 months status post right total knee arthroplasty (TKA) complaining of pain and stiffness for the last four weeks. A clinical photograph is shown in Figure A. Radiographs and a bone scan are shown in Figures B, C and D. Blood work shows an ESR of 14mm/hr (normal 0-12mm/hr) and a CRP of 2mg/L (normal 1-3mg/L). Knee aspiration yields WBC of 1000, 30% PMNs, and a negative gram stain. He finished a 14-day course of antibiotics prescribed to him by his primary care physician one week ago. Which of the following is the most appropriate next step in management?

QID: 1121
FIGURES:

Broad-spectrum, empiric oral antibiotics

2%

(40/1873)

Repeat aspiration after one week

76%

(1423/1873)

Irrigation and debridement of the right knee with a polyethylene liner exchange

7%

(140/1873)

One-stage irrigation and debridement of the right knee with a component exchange

3%

(62/1873)

Two-stage component removal, antibiotic spacer placement and subsequent revision

11%

(200/1873)

L 4 D

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(OBQ04.121) A 58-year-old man has significant pain and stiffness after undergoing right total knee arthoplasty 6 months ago. A current radiograph and bone scan are shown in Figures A and B. Labs show an ESR of 45mm/hr (normal 0-20) and a CRP of 13.5 mg/l(normal <10). Knee aspiration reveals a WBC count of 850 cells/mm(3) with 70% polymorphonuclear cells and no growth on culture. What is the next most appropriate step in management?

QID: 1226
FIGURES:

Two-stage component removal, antibiotic spacer placement and subsequent revision

20%

(567/2846)

Observation with repeat ESR and CRP in one week

17%

(489/2846)

Surgical debridement and polyethylene exchange only

4%

(114/2846)

Repeat aspiration and culture

56%

(1582/2846)

One-stage irrigation and debridement with exchange of all components

3%

(80/2846)

L 3 B

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Evidence (147)
VIDEOS & PODCASTS (48)
CASES (11)
EXPERT COMMENTS (78)
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