Week 1. Osteomyelitis

Question 1

Define the term osteomyelitis

Answer 1

Inflammation of bone, usually caused by bacteria but occasionally by mycobacteria or fungi

Question 2

How do pathogens reach bones

Answer 2

• Haematogenous
• Traumatic spread
• Diabetes
• Contiguous spread

Question 3

What are the main sources of bacteria in haematogenous osteomyelitis

Answer 3

• Staphylococcus Aureus

- Golden staph (commonly found in hospitals)

Question 4

Discuss the Pathogenesis of haematogenous osteomyelitis in children and in adults.

Answer 4

Transient bactermia of unkown source in adults and children.

Site for children metaphyses, Adults, Diaphysis

Pathological process. Children, rapid bone destruction leading to necrosis and abscess formation. In adults it’s much slower, bone destruction leading to necrosis and abscess formation

Consequence.
Children. Sequestrum (separation of dead and living bone) Involcrum (reactive bony growth) and sinus tract formation

Adults. Sequestrum. pathological fractures

Question 5

Discuss the typical clinical picture of acute haematogenous osteomyelitis in children and adults.

Answer 5

Children.
Rapid/ sudden onset.
SSx
- high fever, chills, nausea
- pain (rapidly increasing)
- local muscle spasm, oedema, and warmth

Adults.
History. May have had recent infection (UTI, URTI/LRTI, skin)
Insidious onset.

SSx

• Fever (moderate), malaise, anorexia / weight loss
• Inflammation (pain, swelling, redness) - usually lasts ~ 5-7 days

Question 6

List the types of investigations commonly employed to diagnose osteomyelitis. Write brief explanatory notes on each method.

Answer 6

• History and clinical examination - Will differ between adults and children. However, both will display signs of local inflammation and systemic ssx of infection
• Biopsy - needle aspiration normal in 25% of cases
• Blood tests - cultures (+ve in 50% of cases), increased WBCs, CRP, ESR
• Imaging:
• • Radiography - bony changes not evident for 2-3/52
• • MRI - effective in early detection and surgical localisation
• • radionuclide bone scan - Commonly technetium 99, initial modality of choice
• • CT scan - most useful in vertebral lesions
• • US - may show changes after 1-2/7 after symptom onset
• • X-Ray - soft tissue oedema (3-5/7 post-infection), bony changes (periosteal elevation and subperiosteal new bone formation –> cortical and medullary lucency)