Week 4 - Bone and Joint Infections

Question 1

What are the three types of OM?

Answer 1

1. Haematogenous
2. Contiguous focus of infection with venous insufficiency
3. Contiguous focus of infection without venous insufficiency

Question 2

What are some causes of OM?

Answer 2

50% are from surgery./trauma
Sporting accidents
Orthopaedic device infections

Question 3

Where do haematogenous OM infections occur?

Answer 3

Long bone in children and growing metaphysis –> where blood flow is the highest
Vertebral in adults

Question 4

Which bones account for nearly 50% of haematogenous OM?

Answer 4

Femur and Tibia

Question 5

Describe OM

Answer 5

Invasive bacteria cause inflammatory reactions:

• Leukocytes release enzymes that lyse bone, causing oedema, vascular congestion and small vessel thrombosis
• Impaired medullary and periosteal blood supply

Question 6

What happens to the structure of bone during OM?

Answer 6

Microabscesses form within loops of metaphysis

• Periosteum is elevated and raised by pus
• If gets through cortex, tracks along length of bone
• Can get necrosis in cortical bone from impaired blood flow

Question 7

How is chronic osteomyelitis formed?

Answer 7

• Production of deviated infected bone (sequestra), which ends up losing blood supply and dying
• Body forming new bone (involucrum) next to sequestrum

Question 8

What part of OM leads to bone sclerosis and deformity?

Answer 8

Involucrum - body forming new bone

Question 9

How do you cure acute OM?

Answer 9

Antibiotics - longer in adults than children