Osteomyelitis Flashcards

1
Q

What is osteomyelitis?

A

An infection of the bone

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2
Q

What bones are principally affected in osteomyelitis?

A

Long bones, with tiba > fibia > humerus

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3
Q

What can osteomyelitis be divided into?

A
  • Acute
  • Subacute (2-3 weeks)
  • Chronic
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4
Q

Where in the bone is infection usually seen in osteomyelitis?

A

In the metaphyseal region of bones

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5
Q

How does infection get to the bone in osteomyelitis?

A
  • Haematogenous route
  • Direct inoculation
  • Local extension from adjacent sites
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6
Q

Where does the infection come from when it is spread via haematogenous route in osteomyelitis?

A

Most infections are spread from a site of entry, e.g. respiratory, GI, ENT, or skin sites

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7
Q

What might cause direct inoculation of infection causing osteomyelitis?

A
  • Open fractures

- Penetrating wounds

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8
Q

When can infection spread to the adjacent joint?

A

In the infant

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9
Q

Why can infection spread to the adjacent joint in the infant?

A

Because the transphyseal vessels are patent

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10
Q

How does infection tend to spread in adolescents?

A

Through the medullary canal

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11
Q

Can organisms be isolated on testing in osteomyelitis?

A

Not always

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12
Q

Why can organisms not always be isolated in osteomyelitis?

A

The yield for bacterial growth from synovial fluid and bone aspirate is small

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13
Q

What is the most common bacteria causing osteomyelitis in all age groups?

A

S. Aureus

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14
Q

What other organisms can cause osteomyelitis in neonates?

A
  • Group B streptococcus

- Gram -ve enteric bacilli

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15
Q

What other organisms can cause osteomyelitis in <2 years?

A

Haemophilus influenzae

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16
Q

What other organisms can cause osteomyelitis in >2 years?

A
  • Gram +ve cocci

- Pseudomonas aeruginosa

17
Q

What other organisms can cause osteomyelitis in adolescents?

A

Neisseria gonorrhoeae

18
Q

What are the risk factors for osteomyelitis?

A
  • Infant

- Male

19
Q

What % of cases of osteomyelitis occur in the first 2 years?

20
Q

How does the presentation of osteomyelitis differ in infants compared to older children?

A

The presentation is more insidious in infants, in whom swelling or reduced limb movement is the initial sign

21
Q

How does osteomyelitis present in older children?

A
  • Pain
  • Limping
  • Refusal to walk/weight bear
  • Fever
  • Malaise
  • Flu-like symptoms
  • Overlying bone tenderness, with or without swelling
22
Q

What might occur in the adjacent joint in osteomyelitis?

A

Sterile effusion

23
Q

What investigations should be done in osteomyelitis?

A
  • Bloods
  • X-ray affected bone
  • US-guided aspiration
  • MRI
  • Open biopsy may be necessary
24
Q

What bloods should be done in osteomyelitis?

A
  • FBC
  • ESR
  • CRP
  • Blood cultures
25
In what % of cases of osteomyelitis are blood cultures positive?
50%
26
What might be found on x-ray of bone in the early stages of osteomyelitis?
May be normal, possibly with soft tissue oedema visible
27
What might be found on x-ray of bone in late stages of osteomyelitis?
Metaphyseal rarefaction
28
When do destructive changes in bone appear on x-ray in osteomyelitis?
After 10 days
29
What is the purpose of US-guided aspiration in osteomyelitis?
For microscopy and culture
30
What is the purpose of MRI in osteomyelitis?
Soft tissue assessment
31
What might be found on MRI soft tissue assessment in osteomyelitis?
- Bone marrow involvement - Abscess formation - Joint effusion - Subperisoteal extension
32
What are the differential diagnoses of osteomyelitis?
- Septic arthritis - Osteosarcoma - Trauma or fracture - Rheumatoid disease - Toxic synovitis
33
What is involved in the medical management of osteomyelitis?
IV antibiotics for a minimum of 2 weeks, or until clinical recovery with acute-phase reactants normalising, followed by oral antibiotics for 4 weeks
34
What is required when deciding on antibiotics for osteomyelitis?
Early liason with microbiologist
35
What are the surgical options in the management of osteomyelitis?
- Aspiration or surgical decompression of subperiosteal space - Surgical drainage
36
When might aspiration or surgical decompression of the subperiosteal space be performed?
If the presentation is atypical, or in immunodeficient children
37
When is surgical drainage performed in osteomyelitis?
If the condition does not respond rapidly to antibiotic therapy
38
What is done to the limb in osteomyelitis, in terms of mobilisation?
The affected limb is usually rested in a splint, then mobilised
39
What are the potential complications of osteomyelitis?
- Sepsis - Pathological fractures - Sequesteration - Growth disturbance