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MSK > Osteomyelitis > Flashcards

Osteomyelitis Flashcards

1
Q

What is osteomyelitis?

A

Progressive infection of the bone [or bone marrow] and surrounding soft tissue often caused by pyogenic bacteria

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2
Q

What are the different types of bone infection?

A
  • Acute
  • Chronic
  • Specific (eg TB)
  • Or non-specific (most common)
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3
Q

Who does acute osteomyelitis commonly affect? And RF?

A
  • Mostly children (different ages)
  • Boys > girls
  • History of trauma (minor)
  • Other disease
    • Diabetes, rheum arthritis, immune compromise, long-term steroid treatment, sickle cell
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4
Q

How does acute osteomyelitis spread?

A
  • Haematogenous spread: children and elderly
  • Local spread from contiguous site of infection – trauma (open fracture), bone surgery (ORIF), joint replacement
  • Secondary to vascular insufficiency
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5
Q

What are some of the sources of infection in acute osteomyelitis?

A
  • In infants: infected umbilical cord
  • In children: boils, tonsilitis, skin abrasions
  • In adults: UTI, arterial line
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6
Q

What are the most common infection organisms in acute osteomyelitis?

A

Staph aureus

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7
Q

Which long bones are affected by acute osteomyelitis?

A

Effects long bones at the metaphysis:

  • Distal femur
  • Proximal tibia
  • Proximal Humerus
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8
Q

Which joints are affected by acute osteomyelitis?

A

Effects joints with intra-articular metaphysis:

  • Hip
  • Elbow
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9
Q

What are 8 steps of pathogenesis of acute osteomyelitis?

A
  1. Starts at metaphysis
  2. Vascular stasis (venous congestion and arterial thrombosis)
  3. Acute inflammation - increased pressure
  4. Suppuration
  5. Release of pressure
  6. Necrosis of bone (sequestrum)
  7. New bone formation (involucrum)
  8. Resolution (or not)
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10
Q

What are clinical features of acute osteomyelitis in infant?

A
  • Aysmptomatic or very ill
  • Failure to thrive
  • Drowsy/irritable
  • Metaphyseal tenderness and swelling
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11
Q

What are clinical features of acute osteomyelitis in children?

A
  • Severe pain
  • Reluctancy to move; not weight bearing
  • May have swinging pyrexia and tachycardia
  • Malaise
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12
Q

What are clinical features of acute osteomyelitis in adults?

A
  • Primary OM seen commonly in thoracolumbar spine
  • Backache
  • History of UTI
  • Elderly, DM, immunocompromised
  • Secondary OM is far more common: often after open fracture or surgery
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13
Q

What do we do to diagnose acute osteomyelitis?

A
  • History and examination
  • FBC and diff WBC
  • ESR, CRP
  • Blood cultures x3 (at peak of temp. 60% will be positive)
  • U&Es
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14
Q

DDx for acute osteomyelitis?

A
  • Acute septic arthritis
  • Acute inflammatory arthritis
  • Trauma (fracture, dislocation, etc.)
  • Transient synovitis (“irritable hip”)
  • Soft tissue infection
    • Cellulitis
    • Necrosing fasciitis
    • Erysipelas
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15
Q

What investigations do we run for acute osteomyelitis?

A
  • X-ray (normal in the first 10-14 days)
  • Ultrasound
  • Aspiration
  • Isotope Bone Scan (Tc-99, Gallium-67)
  • Labelled white cell scan (Indium-111)
  • MRI
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16
Q

What can be seen on radiographs as acute osteomyelitis progresses?

A
  • Early radiograph: minimal changes
  • 10-20 days early periosteal changes
  • medullary changes - lytic areas
  • late osteonecrosis - sequestrum
  • late periosteal new bone - involucrum
17
Q

What is the Tx for acute osteomyelitis?

A
  • Supportive treatment for pain and dehydration - general care and analgesia
  • Rest and splintage
  • Antibiotics:
    • route (IV/oral switch – 7-10 days?)
    • duration (4-6 wks – depends on response, ESR)
    • choice - empirical (Fluclox + BenzylPen) while waiting
18
Q

Why will antibiotics sometimes fail as treatment for acute osteomyelitis?

A
  • Drug resistance
  • Bacterial persistance
  • Poor host defences
  • Poor drug absorption
  • MRSA etc….
19
Q

When is surgery indicated for acute osteomyelitis?

A

Once there is dead bone or biofilm established antibs alone cannot cure and thorough surgical debridment is required.

  • Aspiration of pus for diagnosis & culture
  • Abscess drainage
  • Timing, drainage, lavage
20
Q

Complications of acute osteomyelitis?

A
  • Septicaemia, death
  • Metastatic infection
  • Pathological fracture
  • Septic arthritis
21
Q

What causes chronic osteomyelitis?

A
  • May follow on from acute osteomyelitis
  • May start de novo: following an operation, following open fracture, immunosuppresed, DM, elderly
  • Repeated breakdown of healed wounds
22
Q

What is the causative organism for chronic osteomyelitis?

A

Mostly Staph. Aureus, E. Coli, Strep. pyogenes, Proteus

23
Q

What are the 4 steps for pathogenesis of chronic osteomyelitis?

A
  1. Cavities
  2. Dead bone (retained sequestra)
  3. Involucrum
  4. Histological picture is one of chronic inflammation
24
Q

What are the complications of chronic osteomyelitis?

A
  • Chronically discharging sinus + flare-ups
  • Ongoing infection
  • Pathological fracture
25
Q

What are some of the Tx options for chronic osteomyelitis?

A
  • long-term antibiotics
  • Eradicate bone infection surgically
  • Treat soft tissue problems

MSK (33 decks)

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