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Year 3 MSK > Osteomyelitis (from Bone & soft tissue infection) > Flashcards

Osteomyelitis (from Bone & soft tissue infection) Flashcards

1
Q

What is osteomyelitis?

A

Infection of bone

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2
Q

What age groups, genders etc tend to be affected by osteomyelitis?

A

Mostly children (Boys > girls)

May be associated with recent minor trauma

If it occurs in adults - usually in those with other diseases

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3
Q

What other diseases place adults at risk of osteomyelitis?

A

Diabetes

Rheumatoid arthritis

Immunocompromised in other ways

Long term steroid treatment

Sickle cell disease

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4
Q

How can osteomyelitis spread?

A

Haematogenous spread

  • esp in children and elderly

Local spread from contiguous site of infection

  • trauma (open fracture)
  • bone surgery (ORIF) or joint replacement surgery

Secondary to Vascular insufficiency

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5
Q

What are some sources of infection for osteomyelitis specific:

a) in infants (< 1)
b) in children
c) in adults

A

a) Infants - Infected umbilical cord
b) Children - boils, tonsilitis, skin abrasions
c) UTI, arterial line

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6
Q

What are the most common infective organisms for osteomyelitis in infants?

A

Staph aureus

Group B Strep

E.coli - predominantly in neonates

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7
Q

What are the most common infective organisms for osteomyelitis in children?

A

Staph aureus

Strep pyogenes

Haemophilus influenzae (less so since vaccine)

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8
Q

What organisms cause osteomyelitis in adults?

A

Staph aureus

Mycobacterium tuberculosis

Pseudomonas aeroginosa

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9
Q

What types of osteomyelitis-causing bacteria are associated specifically with prostheses?

A

Coagulase-negative Staphylococci (Staph epidermis)

Propionibacterium spp

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10
Q

What osteomyelitis bacterium is associated with penetrating foot injuries?

A

Pseudomonas aeroginosa

Nike Air-ginordans

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11
Q

In acute osteomyelitis, infection by what organism is associated with each…

a) Diabetic foot and pressure sores
b) Sickle cell disease
c) Occupation as a fisherman or filleter
d) HIV/AIDS

A

a) Diabetic foot/pressure sores
* Mixed infection incl. anaerobes
b) Sickle cell disease
* infection w. Salmonella spp.
c) Fisherman
* infection w. Mycobacterium marinum
* d)* HIV/AIDS or debilitating illness
* infection w. Candida

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12
Q

Vertebral osteomyelitis is associated with what organisms?

A

Staph aureus

TB

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13
Q

How can you investigate osteomyelitis?

A

History & Examination - raised pulse & temp

FBC + Differential WBC - neutrophil leucocytosis

ESR, CRP - gen will be elevated in osteomyelitis

Blood cultures X3 - (at peak temp)

U&E’s

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14
Q

What imaging modalities would you use for a patient with acute osteomyelitis?

A

X-ray - (will be normal in first 10-14 days)

Ultrasound - will demonstrate sub-periosteal puss

Aspiration - if puss is present

MRI - highly sensitive, esp good for vertebral osteom.

Isotope bone scan, white cell scan

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15
Q

On an x-ray of someone with osteomyelitis in their tibia

How will this x-ray change over the course of their infection?

A

Early radiographs - minimal change

10-20 days:

  • early periosteal changes (whitening of cortex)
  • medullary lytic areas (areas of bone destruction within the medulla)
    • Visible as grey patches within the bone (almost as if its hollowed out)

Late-stage:

  • Late osteonecrosis (sequestrum)
  • Periosteal new bone formation (involucrum)
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16
Q

What are the differential diagnoses for acute osteomyelitis?

A

Acute septic arthritis

Soft tissue infection*

Trauma

Acute inflammatory arthritis

Transient synovitis - ‘irritable hip’

Rarer:

  • Rheumatic fever, sickle cell crisis, Gaucher’s disease, haemophilia
17
Q

What soft tissue infections are differentials for acute osteomyelitis?

A

Cellulitis - deep infection of subcut. tissues (Gp A Strep)

Erysipelas - superficial cellulitis with red raised plaque (Gp A Strep)

Necrotising fasciitis - aggressive fascial inf. - Gp A strep, clostrid.

Gas gangrene - grossly contaminated trauma (Clost. perfringens)

Toxic shock syndrome - secondary wound colonisation (Staph A)

18
Q

How is the microbiological diagnosis made for acute osteomyelitis?

A

1) Blood cultures (x3):

  • Always done
  • Likely positive in patients w/ haematogenous spread

2) Aspiration / bone biopsy
3) Tissue or swabs for prosthesis infections:
* from up to 5 sites around implant at debridement

19
Q

What are the main features of the treatment of acute osteomyelitis?

A

Supportive treatment - for pain & dehydration

  • general care, analgesia

Rest and Splintage

Antibiotics:

  • Start IV then switch oral Abx at 7-10 days
  • Duration depends on response
  • Empirical antibiotics before culture

Surgery - if indicated

20
Q

What ‘empirical’ antibiotics are used to treat acute osteomyelitis before cultures are returned

A

*despite not having culture - bank on it being Staph aureus or group B strep*

Flucloxacillin

BenzylPenicillin

21
Q

When is surgery indicated for osteomyelitis?

A

Surgery of some form is usually needed in osteomyelitis - only very early stages could be treated with only abx

  • Aspiration of pus - for diagnosis/culture
  • Abscess drainage
  • Debridement of dead/infected tissue
22
Q

What are the potential complications of osteomyelitis?

A

Metastatic infection - esp heart valves etc

Pathological fracture

Septic arthritis

Septicaemia, death

Altered bone growth

Chronic osteomyelitis

23
Q

How can chronic osteomyelitis arise?

A
  • Secondary to acute osteomyelitis
  • Primary (de novo):
    • following operation
    • following open fracture
    • immunosuppressed, diabetics, elderly, drug abusers, etc
24
Q

What microorganisms are usually seen in chronic osteomyelitis?

A

Often mixed infection - but with the same organisms each flare up

Mostly:

  • Staph. Aureus
  • E. Coli
  • Strep. pyogenes
  • Proteus
25
Q

What are the pathological features of osteomyelitis?

A
  • cavities, poss. sinus(es)
  • dead bone (retained sequestra)
  • involucrum
  • histological picture is one of chronic inflammation
26
Q

What are the complications of chronic osteomyelitis?

A

Chronically discharging sinus + flare-ups

Ongoing (metastatic) infection (abscesses)

Pathological fracture:

  • serious is chronically infected bone will not heal

Growth disturbance + deformities

  • if near growth plates

Squamous cell carcinoma (0.07%)

27
Q

How is chronic osteomyelitis treated?

A

Eradicate bone infection - surgically (multiple operations)

Long term antibiotics? - either local (cement etc) or systemic

Treat soft tissue problems

Others:

deformity correction

massive reconstruction

amputation

28
Q
A

Year 3 MSK (42 decks)

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