9.7 Bone Fracture

Question 1

What are the names of the 4 stages of bone fracture healing?

Answer 1

1. Haematoma formation (AKA inflammatory phase)
2. Soft callus
3. Hard callus
4. Remodelling

Question 2

How long does the haematoma phase (AKA inflammatory phase) of bone fracture healing last? Describe it.

Answer 2

• Lasts ~1 week
• Ruptured blood vessels bleed, leading to clotting
• Recruitment of inflammatory cells to scavenge for pathogens and clean up debris

Question 3

Describe the soft callus stage of bone fracture healing. How long does it last.

Answer 3

• Lasts until ~6wks after fracture
• Mesenchymal stem cells differentiate into chondrocytes, and release angiogenic factors
• Fibrocartilage/collagen matrix is formed
• Blood vessels bring in osteoblast progenitor cells, permitting future bone formation

Question 4

Describe the hard callus stage of bone fracture healing. How long does it last?

Answer 4

• Osteoblasts secrete organic bone matrix; matrix is calcified
• Osteocytes form as they are embedded in bone matrix

Question 5

Describe the last phase of bone fracture healing

Answer 5

• Remodelling
• Osteoblasts secrete new osteoid, which is calcified into new bone
• Osteoclasts resorb unneeded bone
• Over time, as the bone begins to bear weight again, the inessential is removed (uncarved block)

Question 6

Which of RANK/RANKL do osteoclasts/blasts express? Which of these does denosumab target?

Answer 6

RANK: Clast (stinky)
RANKL: Blast

Denosumab targets RANKL

Question 7

How do bisphosphinates work?

Answer 7

Cause osteoclast apoptosis

Question 8

Describe 4 types of incomplete bone fractures. Which patient type do we see them in?

Answer 8

1. Bowing
2. Fissure (crack)
3. Fissure (with bending)
4. Torus (buckle)

Question 9

Describe communited fractures

Answer 9

Bone that has been broken into three or more pieces

Question 10

What typically causes linear/stress fractures?

Answer 10

Repetitive forces.

Question 11

Give an example of a common cause of spiral fracture

Answer 11

Arm wrestling.

Question 12

Describe segmental fractures

Answer 12

Bone is broken in at least two places

Question 13

Describe three types/locations of fractures

Answer 13

• Avulsion (pulling off of chunk that’s attached to tendon/ligament)
• Intra-articular
• Extra-articular

Question 14

The cortical thickness of a bone differs superiorly/inferiorly from the site of a fracture. What type of fracture is this more likely to be?

Answer 14

Spiral

Question 15

Why do we take images from multiple views when a fracture is suspected?

Answer 15

• May not always show on one view
• Enables better visualisation of any displacement
• Can give better indication of joint involvement

Question 16

What are the 4 principles of fracture management?

Answer 16

1. Reduction
2. Hold
3. Maintenance of blood supply
4. Rehabiliation

Question 17

Anatomical vs functional fracture reduction

Answer 17

Anatomical: get back into perfect positoin

Functional: restore length, alignment, rotation; not aiming to put back together perfectly

Question 18

Describe some methods of holding a fracture reduction in place (external and internal)

Answer 18

• Splint
• Traction
• External fixator
• Plates
• Screws

Question 19

List some complications associated with fracture/treatment of bone fracture

Answer 19

Immediate:
- Fat embolus
- Anaethesia rxn
- Loss of neurovascular supply
Early:
- DVT/PE
- Infection
- Pain
- Loss of fixation
- Compartment syndrome
Late:
- Non/malunion
- Growth disturbance
- Chronic pain

Question 20

Describe analgesic use in bone fractures (according to UpToDate)

Answer 20

Mild: NSAIDs
Severe: Minimum effective dose of opioids