bone and joint infections Flashcards

-septic arthritis -pott's disease -osteomyelitis -prosthetic bone + joint infection

1
Q

Define septic arthritis

A

infectious agent in a joint leading to arthritis

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2
Q

Define osteomyelitis

A

infection and inflammation of bone marrow

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3
Q

Difference between acute + chronic septic arthritis

A
acute = PYOGENIC (fever + malaise)
chronic= non pyogenic
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4
Q

Most common organism causing septic arthritis

A

staphylococcus aureus

  • gram positive cooci
  • 60% all cases
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5
Q

Pathogenesis is septic arthritis

A

infection in joint

  • activates innate immune system - immune cells lead to pro-inflammatory cytokine release - joint destruction
  • toxins + enzyme released by the pathogen itself - joint destruction
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6
Q

Most commonly affected joint in septic arthritis

A

knee joint = 50% cases

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7
Q

Biggest risk factors for septic arthritis in adults

A
  • pre-exisitng arthritis = OA/RA

- trauma (surgery/joint replacement)

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8
Q

Biggest cause for septic arthritis in kids

A

idiopathic

followed by pre-existing infection

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9
Q

Synovial joint examination results in septic arthritis

A

SF- purlent (yellow-puss)

- high leukocytes count
- gram stain positive (1/3rd cases)
 - low glucose (respiration for pathogens)
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10
Q

Blood test results in septic arthritis

A
  • raised ESR or CRP (inflammation)

- neutrophilia (esp in kids)

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11
Q

Radiological changes in septic arthritis

A

-soft tissue swelling
-joint capsule distension
(>2wks before changes seen - joint destruction already occurred)

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12
Q

Differential diagnosis for septic arthritis

A
  • gout
  • pseudogout
  • OA
  • RA
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13
Q

Radiological features for septic arthritis

A

similar presentation to OA

  • narrowing joint space
  • bone erosions
  • effusion

BUT CYST FORMATION + NO OSTEOPHYTES

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14
Q

Management of septic arthritis

A
  1. DRAINAGE - debridement + wash out (lowers bacterial load)
  2. broad spectrum antibiotics (prior to blood culture)
  3. blood culture
  4. gram specific antibiotics
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15
Q

Name some broad spectrum antibiotics

A

CI-PRO-FLOXA-CIN

PIPER-A-CILLIN

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16
Q

Name an antibiotic which can be given as a foam directly to the joint

(instead of standard oral method for antibiotics)

A

CLINDA-MYCIN

17
Q

Name a gram positive antibiotic

A

FLUCLOXACILIN

18
Q

Name an antibiotic used specifical in chronic osteomyleitis

A

vancomycin (with cement beads)

19
Q

What is the most common route of infection in septic arthritis and osteomyelitis

A

HAEMTOGENOUS

20
Q

what type of osteomyelitis is seen more commonly in kids

A

acute OM

-kids are vulnerable to OM - due to open EGP

21
Q

What is Pott’s disease

A

OM of the vertebral bodies caused by infection with tuberclin (TB)

(spinal OM =>45yr olds)

22
Q

what are the 2 predisposing factors for OM

A

1.impaired blood flow
diabetes + DVT + radition fibrosis + small risk with SC patients
2.impaired immunity -malnutrition, elderly, neonates + infants (not fully vaccinated + underdeveloped immune system)

23
Q

In OM, what is the biggest predisposing factor for impaired blood flow

A

DIABETES MELLITUS (30-40% of OM patients)

24
Q

clincial features of OM

A
  • abrupt onset of fecer (esp in kids)
  • decreased limb movement
  • localised
25
Q

diagnosis of OM

A

RADIOLOGICAL FINDINGS - lytic center with ring of sclerosis

+blood culture

26
Q

Complications of OM

A
  • amyloidosis

- SCC

27
Q

Management of OM

A
  • surgical debridement + wash out (remove dead bone)
  • reconstruct bone (using allograft + autograft)
  • antibotics (4-6wks- 1st 2 wks IV)
28
Q

Prosthetic bone and joint infection

  1. causes
  2. RF
  3. prevention
A
  1. inoculation at surgery / post op sepsis
  2. old age/obesity/ RA/corticosteroid therapy
  3. aseptic operating theatre/pre-op antibiotics
29
Q

Management options for prosthetic bone + joint infection

A
  1. retain/ remove +replace prosthesis - debridement + wash out + antibiotics (then replace
  2. resection athroplastyr
  3. L.T supressive antibiotics