Principles of fixation

Question 1

What are the 2 types of bone healing?

Answer 1

Primary - less than 1mm gap

Secondary - or gap healing in 3 stages

1. Hematoma formation
2. Primary callus formation (fibrocartilagenous)
3. Bony callus formation

Question 2

What are the 3 zones of a mandible fracture regarding forces?

Answer 2

superior to inferior
Tension zone - near teeth
Neutral zone - near AIN canal
Compression zone - inferior to canal

Question 3

4 principles of internal fixation

Answer 3

1. Anatomic reduction
2. Stable fixation and immobilization
3. Maintain blood supply
4. Return to early function

Question 4

define Rigid vs non-rigid fixation
Rigid
Non-Rigid

Answer 4

Rigid fixation: any type of directly applied bone fixation that prevents interfragmentary movement between the fracture segments when that bone is under active load

Non-Rigid fixation: movement occurs in intermaxillary segments which can allow for non or mal-union

Question 5

4 examples of Rigid fixation?

Answer 5

Reconstruction plate
Bone plates (2…like inferior border/mini plate superior)
2 lag screws
inferior plate and arch bar

Question 6

What do compression plates do?

Answer 6

they have angled screw holes so that when tightening the screws, they pull the 2 bone segments towards each other allowing for more primary/contact healing