Bones and Fractures

Question 1

What are the main types of bone?

Answer 1

Lamellar bone: dense, strong bone formed by regular arrangements of collagen

• • Cortical bone: forms strong outer layer
• • Trabecular bone: inner spongy layet

Woven bone: mechanically weak bone formed by disorganised arrangements of collagen fibres.
– Found in immature bone and healing bone

Question 2

What are the main types of bone formation?

Answer 2

Intramembranous formation:
Formation of bone from mesenchyme in embryronic development. Skull bones, mandible and clavicle.

Endochondral formation:
Formation of bone using cartilage as a precursor. Most bone is formed this way.

Question 3

How can we classify fractures?

Answer 3

1. Traumatic fractures
   - Due to excessive force in healthy bone
   - Trauma, avulsion

2, Stress fractures
- Due to repetitive strain on bone e.g. foot fractures in runners

3. Pathological fractures
   - Due to normal forces acting on diseased bone e.g. osteoporosis, Paget’s

Question 4

What are the phases of fracture healing?

Answer 4

1. Inflammation
   - Formation of haematoma
   - Recruitment of leukocytes and fibroblasts
2. Repair
   - Proliferation of fibroblasts and osteoblasts
   - Endochondral ossification
3. Remodelling
   - Wolff’s Law: Bone remodels in response to mechanical stress on it

Question 5

What are the steps of fracture management?

Answer 5

1. Resuscitate (ATLS)
2. Reduce (restore anatomical alignment)
3. Restrict
4. Repair

Question 6

How can a fracture be reduced?

Answer 6

Closed reduction:

• Manipulation under anaesthetic.
• Use traction to disimpact and then manipulation to align

Open reduction:

• Surgical
• Accurate reduction
• Good for open fractures and multiple fractures in same limb

Traction:

• Not really used anymore
• applying forces to oppose the contraction of muscle groups
• Skin traction and skeletal traction

Question 7

How can a fracture be restricted?

Answer 7

Fixation is important as it reduces strain on the fracture, resulting in more bone formation, less pain and greater stability.

Non-surgical fixation:

• Slings
• Plaster casts (use back-slab or split cast in first 48h due to risk of compartment syndrome)
• Functional bracing

Surgical fixation:

• Internal fixation: pins, screws, nails
• External fixation: fragments held in position by pins and wires and connected to an external frame (open #s)

Question 8

Complications of fractures

Answer 8

Immediate:

• Neurovascular damage: nerve palsies, paralysis
• Visceral damage

Early:

• Compartment syndrome
• Infection
• Fat embolism and ARDS

Late:

• Malunion
• AVN
• Post-trumatic arthritis
• Complex regional pain syndrome

Question 9

How does complex regional pain syndrome present?

Answer 9

• Weeks-months after injury
• Pain in a neighbouring area (not the traumatised area)
• Skin is swollen and shiny
• Temperature (hot and sweaty, or cold and cyanosed)
• Neurological: weakness, hyperreflexia, dystonia, contractures
• Usually self-limiting