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Host and Defense > EXAM 2 Bone and Joint Infections > Flashcards

EXAM 2 Bone and Joint Infections Flashcards

1
Q

describe the hematogenous source of bone and joint infections

A
  • monomicrobial (one organism infects the bone)
  • staph aureus, coagulase-negative stahylococci, gram negative rods, streptococci
  • long bones in children, vertebrae in adults
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2
Q

describe contiguous spread as a source of bone and joint infections

A
  • from the outside in
  • tends to be polymicrobial
  • periodontal, decubitus ulcers
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3
Q

describe direct inoculation as a source of bone and joint infections

A

result of trauma or surgery

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4
Q

describe the pathophysiology of bone and joint infections

A
  • source of bacteria introduced via hematogenous, contiguous spread, or direct inoculation
  • inflammatory exudate leads to increased intramedullary pressure
  • subsequent extension to cortex and periosteum
  • blood supply interrupted leading to necrosis
  • sequestra - separated dead bone
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5
Q

describe the anatomical classifications of the 4 stages of osteomyelitis

A
  • stage 1 - medullary osteomyelitis, confined to the medullary cavity of the bone
  • stage 2 - superficial osteomyelitis, involves only the cortical bone
  • stage 3 - localized osteomyelitis, usually involves both cortical and medullary bone but does not involve the entire diameter of the bone
  • stage 4 - diffuse osteomyelitis, involves the entire thickness of the bone, with loss of stability
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6
Q

describe acute osteomyelitis

A
  • infection prior to development of sequestra
  • usually less than 2 weeks
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7
Q

describe chronic osteomyelitis

A
  • infection after sequestra have formed
  • other hallmarks include formation of involucrum, bone loss and sinus tract formation
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8
Q

describe the clinical presentation of acute osteomyelitis

A
  • gradual onset over several days
  • dull pain/local tenderness on exam
  • warmth, erythema, swelling, fevers may happen but often absent
  • can present as septic arthritis
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9
Q

describe the clinical presentation of chronic osteomyelitis

A
  • mild pain over several weeks
  • may have localized swelling or erythema
  • draining sinus tract
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10
Q

describe the diagnosis of osteomyelitis

A
  • based on culture of bacteria from bone biopsy and pathology with inflammation and osteonecrosis (caveat: positive blood cultures)
  • plain radiographs or MRI
  • lab tests are usually non-specific
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11
Q

describe the diagnosis of chronic osteomyelitis

A
  • suspected based on chronic, poor healing wounds, DM, vascular disease, decubitus ulcers, or in the presence of underlying hardware
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12
Q

the diagnosis of suspected osteomyelitis is based on what?

A
  • clinical presentation
  • +/- bacteremia with typical organisms
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13
Q

although lab tests are usually non-specific, what are the tests used to diagnose osteomyelitis?

A

WBC count, ESR/C-reactive protein, and blood cultures

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14
Q

describe the treatment of acute osteomyelitis

A
  • 3-6 weeks antibiotics +/- surgery (need to debride abscess or due to instability)
  • difference between intravenous versus oral antibiotic therapy not well established
  • issues to consider: oral bioavailability and bone penetration
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15
Q

describe the treatment of chronic osteomyelitis

A
  • 3-6 weeks antibiotics +/- surgery
  • greater role for surgery due to necrotic bone and lack of antibiotic penetration to devascularized bone
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16
Q

for chronic osteomyelitis, oral antibiotics are acceptable, and there is actually more data in support of them than ___

A

IV

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17
Q

T or F

for chronic osteomyelitis, there is no strong evidence to support the recommended duration of 4-6 weeks of oral antibiotic treatment

A

true

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18
Q

for chronic osteomyelitis, there are better cure rates with antibiotics and adjunctive ___

A

surgical debridement

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19
Q

is osteomyelitis of the jaw common?

A

no, it is rare

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20
Q

in osteomyelitis of the jaw, odontogenic infections can spread ___ to the jaw (oral aerobes and anaerobes)

A

contiguously

21
Q

is the mandible or maxilla more susceptible to osteomyelitis of the jaw? why?

A

mandible, due to thinner cortical plates and poor vascular supply

22
Q

in osteomyelitis of the jaw, the periosteum is penetrated with chronic infection with formation of what?

A
  • mucosal or cutaneous abscesses and fistulae
    • lingual aspect of the mandible in region of molar teeth greatest risk
23
Q

what are risk factors for osteomyelitis of the jaw?

A

dental infection, compound fracture, malignancy, irradiation, DM, steroid use

24
Q

what are the symptoms of osteomyelitis of the jaw?

A

mandibular pain, anesthesia or paresthesia on affected side, lymphadenopathy, can progress to trismus

25
Q

describe treatment of osteomyelitis of the jaw

A

combination of surgery and antibiotics targeting oral flora

26
Q

what is arthroplasty?

A

joint replacements

27
Q

joint replacements are highly effective and improve what?

A

the patient’s quality of life, mobility, and independence

28
Q

prosthetic joint infections (PJIs) are the leading cause of ___ failure

A

arthroplasty

29
Q

PJIs lead to the need for more what?

A

more surgery, prolonged antimicrobials, more rehab, and excess costs

30
Q

PJIs are difficult to treat, with failure rates of ___%

A

10-20%

31
Q

what are the arthroplasty-associated risk factors for PJI?

A
  • surgical site infection not involving joint prosthesis
  • prior surgery at site of prosthesis
  • prior native joint infection
  • extended operative time
  • arthroplasty for management of fracture
32
Q

what are the non arthroplasty-related risk factors for PJI?

A
  • obesity
  • DM
  • rheumatoid arthritis
  • immunosuppression
  • use of DMARDs
  • poor nutritional status
  • advanced age
  • malignancy
  • colonization with s. aureus
33
Q

describe the basic microbiology of PJIs

A
  • gram positive cocci ~65%
  • aerobic gram negative bacilli ~6%
  • anaerobes ~4%
  • polymicrobial ~20%
  • culture negative ~7%
  • fungi ~1%
34
Q

what are the gram positive cocci involved in PJIs?

A
  • coagulase-negative staphylococci
  • staphylococcus aureus
  • streptococcus species
  • enterococcus species
35
Q

what are the aerobic gram negative bacilli involved in PJIs?

A
  • enterobacteriaceae
  • pseudomonas aeruginosa
36
Q

what are the anaerobes involved in PJIs?

A
  • propionibacterium species (shoulder arthroplasty)
  • peptostreptococcus species
  • finegoldia magna
37
Q

describe the pathogenesis of PJIs

A
  • skin organisms inoculated at time of implantation
  • hematogenous seeding later
  • small number of organisms adhere to implant
  • form protective biofilm evading antimicrobials and immunity
38
Q

describe the clinical presentation of early PJIs

A
  • within 1-3 months
  • acquired during prosthesis implantation
  • virulent organisms (s. aureus, gram negative)
  • local erythema, swelling, pain, drainage, delayed wound healing, +/- fever
39
Q

describe the clinical presentation of delayed PJIs

A
  • 3 months to 2 years
  • acquired during prosthesis implantation
  • less virulent organisms (CoNS, p. acnes)
  • chronic pain, draining sinus
40
Q

describe the clinical presentation of late PJIs

A
  • >1-2 years
  • hematogenous seeding or late manifestation of surgical infection
  • chronic pain, draining sinus or acute arthritis with sudden pain (hematogenous)
41
Q

what is the basic idea for the treatment of PJIs?

A

surgery + antimicrobials

42
Q

describe the surgical management options for PJIs

A
  • debridement and retention
  • two stage exchange
  • one stage exchange
  • resection arthroplasty with arthrodesis
  • amputation
43
Q

describe antibiotic therapy for debridement and retention as a form of treatment for PJIs

A
  • staphylococcal infection
    • 2-6 weeks of IV therapy + rifampin
    • followed by oral therapy + rifampin (ciprofloxacin, levofloxacin, TMP/SMX, tetracycline, cephalexin, dicloxacin)
    • duration (IV + oral): THA - 3 months, TKA - 6 months
44
Q

describe antibiotic therapy 1 stage exchange as a form of treatment for PJIs

A
  • staphylococcal infection
    • 2-6 weeks of IV therapy + rifampin
    • followed by oral therapy + rifampin (ciprofloxacin, levofloxacin, TMP/SMX, tetracycline, cephalexin, dicloxacin)
    • duration (IV + oral): 3 months
45
Q

describe antibiotic therapy 2 stage exchange as a form of treatment for PJIs

A
  • 4-6 weeks IV therapy or highly bioavailable oral therapy
  • rifampin not recommended because prosthetic material removed
  • antibiotic impregnated cement spacer used to maintain limb length
    • may decrease infection recurrence
  • re-implantation (stage 2) 6 weeks to 3 months
46
Q

osteomyelitis is classified broadly based on what?

A

chronicity and whether it is hematogenous or contiguous

47
Q

treatment strategies for bone and joint infections involve ___ and ___

A

antibiotics and surgical debridement

48
Q

is there a role for antibiotic prophylaxis prior to dental procedures to prevent orthopedic implant infections in most patients?

A

no

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