Osteomyelitis

Question 1

Discuss aetiology and pathogenisis

Answer 1

Predominantly occurs in children and the aged. It is acquired via the haematogenous spred in the former and with co-morbidities such as trauma, surgery, vascular insuffiency and diabetes in the latter.

Haem spread in children typically affects the long bones
In adults it is more common in the spine, SC joints and SI joints.

Question 2

Discuss aetiology by age

Answer 2

Newborn to 4 months

• Staph
• GAS
• GBS

Older children

• Staph
• GAS
• Strep pneumo
• kingella kingae

Adults

• Staph
• strep
• gram-ve

Unusual

• Anaerobic bacteria
• brucella
• TB

Question 3

DIscuss risk factors for osteomyelitis

Answer 3

Recent surgery
-joint replacement

Trauma - including puncture wounds 
Wound infection 
Peripheral vascular disease
Diabetes especially in the present of ulcer 
immunosuppression 
-chemo 
-steroids
IVDU
Sickle cell disase
Iatrogenic

Question 4

Discuss IX of osteo

Answer 4

XRAY
First changes are periosteal elevation
Next are focal lucency
Bone resoprtion or radiodense avascular areas known as sequestra

X-ray changes are not present for between 10 days to 3 weeks after infection.

CT
-able to detect more subtle chagnes

MRI
- Gold standard for imaging

Question 5

Discuss criteria for diagnosis in decreasing order of diagnostic utility

Answer 5

1) bone biopsy with postiive bacterial culture
2) imaging studies demonsteating contiguous soft tissue infection or bone descturiction
3) clinical signs of exposed bone or persistent sinus tract
4) chronic wound over a surigcal site or fracture
5) laboratory evaluation - poisitive blood culture or elevated ESR , CRP

Question 6

Discuss management

Answer 6

IVABS

1) Nil MRSA - fluclox 2g Q6 houlry
2) Post opr with or without implant - vanc 1.5G IV q12houlry
3) Elderly or diabetic, Piptaz + vanc