Infection and the Orthopedic Patient COPY Flashcards

1
Q

Pathophysiology of Musculoskeletal Infections: What kinds of bacteria? 4

A

Bacteria- Large and diversified group

  1. Gram +
  2. Gram –
  3. Anaerobic (no O2)
  4. Aerobic
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2
Q

Pathophysiology of Musculoskeletal Infections

  1. Resistance is a problem. Which bug specifically?
  2. Increased resistance to abx via what?
  3. What is a major cause of nosocomial infections?
A
  1. Staphylococcus aureus
  2. Increased resistance to antibiotics via Plasmids
    - 50% of strains have plasmid mediated resistance
  3. Biofilm:
    Major cause of nosocomial infections
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3
Q

Biofilm production and resistance is becoming common in what species and very common in what other species?

A
  1. increasingly common in staph species,

2. very common in Pseudomonas

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4
Q

Pathophysiology of Musculoskeletal Infections

Homeostasis: once altered bacteria can enter the body such as in surgery. Why?
3

A

Environment is compromised by

  1. diminished blood flow,
  2. oxygen tension and
  3. foreign bodies
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5
Q

Pathophysiology of Musculoskeletal Infections
-Blood supply
One of the most important factors in homeostasis

  1. Multiple studies show as blood flow is ________, the risk of infection increases
  2. Warming an extremity increases microcirculation and vasodilatation = what?
A
  1. reduced

2. increase concentrations of abx’s

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6
Q

Pathophysiology of Musculoskeletal Infections:

Traumatic injury and presence of implants increase the risk of infection

  1. Osseous trauma is what? 2
  2. Osseous trauma is what?
  3. Glycocalyx capsule is what?
  4. Impairs what? 2
  5. Biofilm does not just effect foreign material; it can act similarly with what?
A
    • periosteal injury,
    • microvascular and macrovascular compromise
  1. bacteria have an affinity for the exposed binding sites
  2. composed of fibrous exopolysaccharides within biofilm
    • NL immune function and
    • abx penetration
  3. devitalized bone
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7
Q

Pathophysiology of Musculoskeletal Infections

Host susceptibility of infections
1. Factors that decreases local immune response? 4

  1. Factors that decrease systemic immune response?
    6
A
    • Decreased blood flow
    • neuropathy,
    • trauma,
    • medication (NSAID’s, Rh, steroids)
    • Renal and liver Dz,
    • DM,
    • EtOH,
    • Rh Dz’s,
    • Immunocompromised state
    • Malnutrition
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8
Q

Examples of decreased blood flow that will make hosts more susceptible to infection?
4

A
  1. PAD,
  2. venous stasis,
  3. smoking,
  4. radiation
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9
Q

Diagnostic Modalities in Musculoskeletal Infections
1. Gold Standard?

  1. Pts present how? 5
  2. Other possible symptoms? 5
A
  1. Gold standard is culture of suspected fluid or tissues
  2. Pts often present with
    - pain,
    - warmth,
    - swelling,
    - redness and
    - refusal to bear weight (children especially)
  3. Other symptoms:
    - fever ,chills,
    - night sweats,
    - nausea,
    - vomiting
    - loss of joint motion
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10
Q

Diagnostic Modalities in Musculoskeletal Infections
Serology?
7

A
  1. CBC with Differential
  2. Erythrocyte sedimentation rate (ESR)
  3. C-reactive protein (CRP)
  4. Blood cultures
  5. Gram stain
  6. Frozen section
  7. PCR
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11
Q

Diagnostic Modalities in Musculoskeletal Infections
1. Normal WBC, ESR and CRP= what percent of infection?

  1. ESR: Elevates when and will continue to rise for how long?
  2. CRP elevates when? Peaks when? Returns to normal?
  3. Advantage? 2
A
  1. Normal WBC, ESR and CRP = 95% chance of no infections process
  2. ESR: Elevates within 2 days of infection and will continue to rise fore next 3-5 after appropriate tx
  3. CRP: Elevates within 6hrs, peaks at 48hrs, returns to NL 1 wk after appropriate tx
    • More sensitive
    • Best indicator for diagnosis and for monitoring tx
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12
Q

Diagnostic Modalities in Musculoskeletal Infections

  1. What is gram stain good for?
  2. IL-6: New literature show this can be helpful, especially in what?
A
  1. Gram stain
    Good for tailoring of specific abx
  2. IL-6- periprosthetic infections
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13
Q

Diagnostic Modalities in Musculoskeletal Infections

Radiology
Plain films:  
1. What are the earliest findings?
2. When would you see bony changes?
3. What is a brodies abcess?

INFECTION SHOULD ALWAYS BE ON YOUR DX

A

Always start here: cheap and easy

  1. Soft tissue swelling, loss of tissue planes are earliest findings
  2. Bony changes (must have at least 40% bone loss to see on film) usually seen late in the course of infection or in the setting of chronic infections
  3. Brodies Abscess
    - Brodie abscess is an intraosseous abscess related to focus of subacute pyogenic osteomyelitis. Unfortunately, there is no reliable way radiographically to exclude a focus of osteomyelitis. It has a protean radiographic appearance and can occur at any location and in a patient of any age.
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14
Q

Diagnostic Modalities in Musculoskeletal Infections

  1. What is the next step after plain film?
  2. Other scans available? 3
A
  1. Bone Scan: (three phase bone scan, Tc 99m)
    - “Vague” test
  2. Other scans-
    - Indium 111 leukocyte nuclear scan: (84% sen and 75-94% spec)
    - Gallium citrate scan: (70-80% sen)
    - PET scan: (99% sen and 88% spec): Expensive and time consuming
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15
Q

Diagnostic Modalities in Musculoskeletal Infections
MRI:
1. Often used for?
2. Can be highly sensitive or specific?
3. Cost?
4. Normal bone marrow will look how on MRI?
5. What could be indicative of infection?
6. Useful for anatomy findings such as? 2

A
  1. Often used for infection
  2. Can be highly sensitive
  3. Expensive
  4. Normal bone narrow = high signal on T1
  5. Low T1 signal could be indicative of infection
  6. Useful for anatomy findings:
    - abscess
    - sinus tracts
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16
Q

Musculoskeletal Infections in Adults
1. Most common in pts with what? 3

  1. Osteomyelitis types? 2
A
    • open fractures,
    • DM foot infection
    • recent surgery
    • Hematogenous (transferred by the blood)

-Contiguous focus (caused by a prior infection)

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17
Q

Osteomyelitis:

  1. Hematogenous (transferred by the blood) example?
  2. Contiguous focus is subdivided based on what?
A
  1. Example: Vertebral osteomyelitis

2. Subdivided based on presence or absence of vascular insufficiency

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18
Q

Musculoskeletal Infections in Adults
1. Alternative classification
Describes the anatomic involvement: What are stages 1-4?

  1. Host descriptions? 3
A
1. Describes the anatomic involvement
Stage 1:  Medullary
Stage 2:  Superficial
Stage 3:  Localized
Stage 4:  Diffuse
  1. Describes the host
    - Normal
    - Compromised
    - Treatment worse than the disease
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19
Q
Musculoskeletal Infections in Adults
Hematogenous Osteomyelitis
1. What % of all adult pts?
2. Gender?
3. Whats the most common site? Followed by? 3
4. Most common bacteria?
5. Pts present how?
A
  1. 20% of all adult pts
  2. More common in males
  3. Vertebrae is the most common site,
    - followed by long bones, pelvis and clavicle
  4. S. aureus is the most common bacteria
  5. Pts present with pain and constitutional symptoms (fever, chills, swelling, erythema) either acutely or long standing
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20
Q
Musculoskeletal Infections in Adults
Vertebral Osteomyelitis
1. What age group?
2. Mortality?
3. May involve what? 2
4. What area is most common?
5. Bug?
6. What in IV drug users?
7. Pts present how?
8. What can result with motor/sensory deficits occurring in 15% of pts? 2
A

Vertebral Osteomyelitis

  1. > 50 yo (1-2% are children mean 7.5 yo)
  2. Death is rare
  3. May involve
    - 2 adjacent vertebrae and
    - the disk (diskitis)
  4. Lumbar is most common 45%, thoracic 35%, cervical 20%
  5. S. aureus is the most common
  6. Pseudomonas in IV drug users
  7. Pts present w/ fever, pain over the area for 3 wks to 3 months
  8. Meningitis and abscesses can result with motor/sensory deficits occurring in 15% of pts
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21
Q

Contiguous-focus Osteomyelitis
1. Without generalized vasc insufficiency can be cause by what? 3

  1. Common when? 4
  2. what is the most common bacteria?
  3. Infection occurs about when after the primary cause of the infection?
  4. Pts report what symptoms? 3
  5. Leads to decreased what? 3
A
    • trauma with direct contact to bone,
    • infection spread from soft tissue, or
    • by nosocomial infection
    • ORIF,
    • prosthetics,
    • open fx’s and
    • chronic soft tissue infections
  1. S. aureus
  2. 1 month
  3. pain and fever with drainage of the area
    • bone stability,
    • necrosis and
    • soft tissue damage
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22
Q

Musculoskeletal Infections in Adults

Contiguous-focus osteomyelitis w/ general vas insufficiency

  1. Commonly in who?
  2. Where?
  3. Mutiple bugs like? 4
  4. Present with what? 2 Due to what? 2
A
  1. Diabetics
  2. Small bones of the feet
  3. Multiple bugs:
    - staph,
    - strep,
    - enterococcus,
    - G- bacilli
  4. Present with
    -ulcers,
    -multiple foot problems all
    due to
    -peripheral neuropathy and
    -small vessel disease
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23
Q
Musculoskeletal Infections in Adults
Chronic Osteomyelitis
1. H/O?
2. Pts have recurrence of what? 5
3. Tx? 2
4. With prolonged infection you can develop what? 2
A
  1. h/o osteo
  2. Pts have a recurrence of
    - pain,
    - fever,
    - drainage,
    - erythema
    - swelling
    • Abx alone is usually not helpful
    • Nidus of infection must be removed
  3. With prolonged infection can develop
    - squamous cell carcinoma (Marjolin’s ulcer)or
    - amyloidosis
24
Q

Musculoskeletal Infections in Adults
Dx?
4

A

Difficult

  1. H/P
  2. Lab up
  3. Imaging
  4. Osteomyelitis = “great mimicker”
25
Q

Musculoskeletal Infections in Adults

  1. Osteomyelitis is treated with?
  2. Inital intervention? 5
  3. Treat systemic issues such as? 2
  4. Abx for how long?
A
  1. Osteomyelitis is treated with abx and surgery
    • Adequate drainage,
    • debridement,
    • dead space management,
    • maintenance of blood supply
    • wound care
  2. Treat systemic issues: -nutrition,
    - smoking (this includes all nicotine)
  3. Abx for 4 to 6 wks: this is based on animal models where it takes this long for bone revascularization

Longer than 6wks has not been shown to be more efficacious

26
Q

Musculoskeletal Infections in Adults
Treatment from initial treatment or last debridement
1. Stage 1 Medullary?
2. Stage 2 Superficial?
3. Stage 3 Localized and Stage 4 Diffuse?

A
  1. 4wk abx
  2. 2 wks of abx 100% effective in NL host, 79% effective in compromised host
  3. 4-6wk abx 98% effective in NL host, less so in compromised host
27
Q

Musculoskeletal Infections in Adults

Tx? 3

A
  1. Suppressive antibiotic therapy should initiated when surgical treatment is not and option
  2. Rifampin with a fluoroquinolone or trimethoprim-sulfamethoxazole for 6 months
  3. If this fails then life long suppression
28
Q

Musculoskeletal Infections in Adults

  1. What is the mainstay of tx in osteomyelitis?
  2. When is this complete?
  3. What must all be removed? 2
  4. Bony defects can be filled with?
A
  1. Surgical debridement is the mainstay of osteomyelitis
  2. Debridement is complete when the bone bleeds “paprika sign” this ensures the nidus has been removed
    • If it is dead it must be removed
    • All foreign bodies should be removed
  3. Bony defects can be filled with autograft, or spanned with external fixation
29
Q
Musculoskeletal Infections in Adults
Treatment
-Infection in the setting of fracture
1. Will implants need to be removed?
2. Alternative?
3. Often takes how long?
A
  1. All hardware does not have to be removed immediately. Implants can be removed after the fracture has united along with a debridement
  2. Alternatives to internal fixation are external fixators (Ilizarov)
  3. Often takes 8+ months but good healing rates
30
Q

Musculoskeletal Infections in Adults

  1. Think about open fractures as what?
  2. Especially true of what?
  3. Appropriate coverage encourages healing. What are these? 4
A
  1. Open fractures should be should be thought of as soft tissue injuries that happen to have a broken bone.
  2. This is especially true of high-energy injuries. **
  3. Appropriate coverage encourages healing
    - Negative pressure wound dressings
    - Flaps
    - Skin grafts
    - Avoid secondary intention if at all possible
31
Q
Musculoskeletal Infections in Adults
Tx
Hyperbaric chamber
1. Shown to be useful in what? 2
2. Promotes what? 2
3. Increase what in soft tissues?
A
  1. Shown to be useful for chronic osteomyelitis and soft tissue infections
  2. Promotes collagen formation and angiogenesis
  3. Increases oxygen tension in the soft tissues
32
Q

Adult Septic Arthritis
1. Septic OA can occur via multiple routes? 4

  1. Predisposing factors? 6

Incidence: 0.034% to 0.13 for non-gonococcal
3. What is the most common?

A
    • Blood
    • Trauma
    • Contiguous spread
    • IV drug use
    • DM,
    • Rh,
    • steroid use,
    • HIV,
    • malignancy,
    • age
  1. Knee
33
Q

Adult Septic Arthritis

PP? 4

A
  1. Bacteria destroy synovial cell lining
  2. Glycosaminoglycan is destroyed: Loss of fluid retention ability of the cartilage
  3. Increase inflammatory response
  4. Destruction of cartilage
34
Q

Adult Septic Arthritis

  1. Most common bug?
  2. What is now thought to be more common due to IV drug use?
  3. MC non-gonococcal?
  4. Other common bacteria? 2
  5. What is often seen in HIV + persons?
A
  1. Neisseria gonorrhea was the most common organism
  2. S. aureus is now thought to be more common due to IV drug use
  3. S. aureus is the most common non-gonococcal organism
    >40% MRSA
  4. Other common bacteria:
    -E coli,
    -Pseudomonas
  5. Fungal infections can be seen with HIV positive patients
35
Q

What are the MC area for septic arthritis in an adult? 6

A
  1. Knee is the most common 52%,
  2. hip 22%
  3. shoulder 12%
  4. ankle 12%
  5. elbow 12%
  6. wrist 10%
36
Q

septic arthritis

  1. Present with? 2
  2. Blood work? 3
  3. Gold standard dx?
A
  1. Present with
    - warm swollen
    - painful joint
  2. Infectious blood work
    - CBC,
    - ESR,
    - CRP
  3. Aspiration is gold standard
37
Q

Aspiration of joint in spectic arthritis:

  1. What will we analyze?
  2. What WBC = infection?
  3. If first aspiration is less than 50k and you continue to be clinically suspicious then do what?
A
  1. Send for
    - cell count with diff (most important),
    - crystals,
    - gram stain,
    - Cx’s
  2. WBC >50,000 equals infection
  3. If first aspiration is less than 50k and you continue to be clinically suspicious then repeat aspirations as much as needed
38
Q

Adult Septic Arthritis

tx? 4

A
  1. Surgical emergency
  2. Antibiotics immediately: tailor as cultures return
    - Treat for 6 weeks
  3. Arthrotomy and surgical debridement (open or arthroscopic)
  4. Concurrent treatment with NSAID’s has been shown to decrease cartilage damage
39
Q

Musculoskeletal Infections in Pediatric Population

  1. Occurs mainly where on the body?
  2. SPreads how?
A
  1. Ped osteo occurs mainly in high vascular areas at the metaphyseal epiphyseal area
  2. Hematogenous spread is most common
40
Q

Musculoskeletal Infections in Pediatric Population
1. MC bacteria?
2/ Others? 2

A
  1. S. aureus is the most common bacteria 61 to 89%
    • Group A Strep 10%
    • H. influenzae 3 to 7% (immunizations work
41
Q

Other causes of peds MS infections?

  1. What presents with URI?
  2. Sickle cell pts?
  3. Cat scratch dz?
  4. Pucture wounds of the feet?
A
  1. Kingella kingae, presents with a URI
  2. Salmonella, sickle cell patients
  3. Bartonella henselae, cat scratch disease
  4. P aeruginosa, puncture wounds of the feet
42
Q

Musculoskeletal Infections in Pediatric Population
Pathophysiology
1. Pediatric osteomyelitis usually occurs in the metaphysis due to what?

  1. Neonates: periosteum is thin, thus, infection can perforate and do what?
    - This leads to what?
  2. Infants: infection and spread becomes more rare due to what?\
  3. Children: spread limited by what?
A
  1. large vascularity and low flow rate
  2. allow spread to surrounding tissues and joints.
    - septic arthritis and growth plate abnormalities (hips and shoulders are most common)
  3. metaphyseal capillary atrophy
  4. thickening of the cortex
43
Q
Musculoskeletal Infections in Pediatric Population
Dx?
1. Any child with what symptoms?
2. Neonates?
3. Infants, toddlers, young children?
4. Older children and adolescents?
A
  1. Any child w/ a fever and limb pain for 3 days needs to be evaluated
  2. Neonates: pseudoparalysis, pain w/ palpation, swelling, decreased appetite
  3. Infants, toddlers and young children: FUO, limp or NWB, swelling, warmth, erythema
  4. Older children and adolescents: report constant pain that is well localized, fever
44
Q

Musculoskeletal Infections in Pediatric Population

4

A
  1. 36% to 55% will have positive blood cx’s
  2. Plain xray is of limited use
  3. Ultrasound for hip infections
  4. MRI is useful, can increase sensitivity with gadolinium
45
Q

Musculoskeletal Infections in Pediatric Population
Tx:
1. Mainstay?
2. To cover?

  1. How long?
  2. Follow tx with?
  3. Beware of?
A
  1. Mainstay is antibiotics, occasional decompression and drainage of the infected area, (can do this with a 14g needle)
  2. Abx need to cover staph and group b strep
    - Tailor coverage as cultures return
  3. IV or oral abx for 4 to 6 weeks
  4. Follow treatment with CRP
  5. Be aware of side effects
46
Q
Musculoskeletal Infections in Pediatric Population
Tx: Chronic osteomyelitis:
1. 20% of pts with?
2. Occurs after what?
3. Tx? 2
A
  1. 20% of pts with acute hematogenous osteomyelitis
  2. Occurs after inadequate tx of primary infection
    • Treat with I&D followed by 6 to 12 months of abx
    • Debridement must remove the sequestra and intramedullary purulence.
47
Q

Pediatric Septic Arthritis

  1. 80% involve what?
  2. Bacteria enter the joint rapidly due to what?
  3. MC bug?
  4. MC bug in neonate? 2
A
  1. 80% involve the hip
  2. vascular nature of the synovium and lack of a basement membrane
  3. S aureus is most common
  4. In the neonate think of group B strep and gram (-) bacilli
48
Q
Pediatric Septic Arthritis
Dx 
1. Present with? 5
2. Hip infection present with? 4
3. Patients usually present after how long?
4. More difficult to detect in what?
A
  1. Present with
    - fever,
    - edema,
    - erythema,
    - effusion,
    - refusal to ambulate,
    - pseudo paralysis
  2. Hip infection:
    - Flexed,
    - Abducted, and
    - External Rotation.
    - Severe pain with PROM and rotation
  3. Patients usually present after 72hrs
  4. More difficult to detect in neonates
49
Q

Pediatric Septic Arthritis
Dx
Diagnostics? 4

A
  1. Infectious blood work
    - Nonspecific tests, but highly sensitive
  2. Plain x ray
    - Useful to rule out other diagnoses (fracture, Perthes, SCFE)
  3. Gold standard is hip aspiration (impractical)
  4. Hip ultrasound is best test in my opinion
    - Always good to do bilateral hips so you have a “normal” comparison. Additionally, YOU should see the ultra sound
50
Q

Pediatric Septic Arthritis

Tx? 4

A
  1. Antibiotics immediately and tailor as cultures return
    - Duration of at least 3 weeks
  2. Surgical Drainage of septic joints on an emergent basis
  3. Follow treatment with inflammatory markers
  4. Long term follow up for potential growth plate disturbances
51
Q

Periprosthetic Infections

  1. MC bugs? 2
  2. Occur by? 3
A
  1. S aureus and S epidermadis are the most common
  2. Occur by:
    - Direct contact during the surgery
    - After the surgery (draining incision)
    - Hematogenous inoculation
52
Q

Periprosthetic Infections Dx

  1. Symtpoms? 5
  2. Infectious labs? 3
  3. If one of the labs are normal then do what?
  4. Aspiration: What is the most important lab with this?
  5. Normals?
  6. Dont trust what?
A
  1. Symptoms:
    - pain is the first indicator,
    - not changed by activity levels or WB,
    - stiffness,
    - chronic drainage
  2. Infectious labs:
    - CBC w/ diff,
    - ESR,
    - CRP
  3. If normal then not infected
    - If one out of the three are abnormal then aspirate the joint
  4. Aspiration
    Cell count is the most important:
  5. Normal is less than 1,700 w/ 1700 and 65% then 94-97% sensitive and 88-98% specific for periprosthetic infection
  6. Do not trust Gram stains or cultures
53
Q

Periprosthetic Infections

Imaging? 3

A
  1. Plain radiographs may show progressive radiolucent lines around the prosthetic (late finding)
  2. Bone scan can demonstrate a “hot spot”
    Bone scan does not “normalize” for at least 18 months after surgery
  3. Can use as a serial test to access for change
    Indium-111 scan: increases accuracy but can produce false positives
54
Q

How to think about periprosthetic infections
Short term includes? 2

Long term? 3

A

Short term

  1. Less than 4-6 wks after surgery
  2. Acute hematogenous spread

Long term

  1. Greater than 4-6 wks after surgery
  2. No specific inciting event within recent time frame
  3. Chronic pain preceding the diagnosis of a periprosthetic infection
55
Q

Periprosthetic Infections

TX? 3

A

Antibiotics alone: Terrible idea, never the answer

  • Only used in patients who are so systemically ill that they can not tolerate surgery
  • Successful in less than 18% of patients
  1. Surgical debridement with removal of all easily removed components, mechanical scrubbing of retained components and replacement of removed components
  2. Antibiotics for 6 weeks
    I prefer IV and an oral abx (pt needs two drugs)
  3. Followed by single oral therapy for at least a year
56
Q

Periprosthetic Infections
Tx: Two stage revision?
6

A
  1. Long term infections (>6 weeks)
  2. Surgical debridement and removal of all components and foreign bodies (every little piece of cement and suture)
  3. Placement of an antibiotic cement spacer
  4. Antibiotics for 6 weeks as described for single stage
  5. Antibiotic holiday and
    evaluation with infectious blood work
  6. If “normal” then return to surgery for revision arthroplasty
    Year of oral antibiotics
57
Q
Periprosthetic Infections
Alternative tx?
1. Amputation for? 3
2. Fusion? 5
3. Prevention? 2
A
Alternative treatments
Amputation
1. Recommended if 
-life-threatening sepsis, 
-multiple failed revisions, 
-or persistent severe pain
  1. Fusion
    - For TKA,
    - high functioning pt,
    - single joint,
    - young patient,
    - loss of extensor mechanism
  2. Prevention
    - Oral antibiotic prophylaxis for the life of the patient for all invasive procedures (dentist)
    - Single dose of amoxicillin, cephalosporin or clindamycin