Bone Growth & Repair

Question 1

Briefly describe the structure of cortical vs cancellous bone?

Answer 1

Cortical has circular concentric lamellae called osteons around haversian’s canals

Cancellous has trabeculae and marrow

Question 2

Which type of bone resists what type of force, and in which one is longitudinal growth done?

Answer 2

Cortical bone resists bending; torsion

Cancellous bone resists compression, this is where the physis is

Question 3

What are the 4 stages of fracture repair?

Answer 3

Inflammation
Soft Callus
Hard Callus
Bone Remodelling

Question 4

What occurs during the inflammatory phase?

Answer 4

1) Fibroblasts chuff on in
2) Angiogenesis (induced by macrophages)
3) Mesenchymal & Osteoprogenitor cells appear from the endothelial cells

Question 5

What can we give to accelerate the inflammatory phase?

Answer 5

Give platelet concentrates which contain:

• Platelet- derived growth factor
• Transforming growth factor beta
• Insulin like growth factor
• Vascular endothelial growth factor

Question 6

What happens during the soft callus stage?

Answer 6

Swelling subsides and cartilage/fibrous tissue unites the bony fragments
Angiogenesis continues

Question 7

What is GOLD STANDARD during the soft callus stage?

Answer 7

Gold Standard is an Autogenous Cancellous Bone Graft

This is both osteoconductive and osteoinductive

Question 8

What are the disadvantages should we use allograft bone in the soft callus stage?

Answer 8

Not osteoinductive

Risk of disease transmission

Question 9

What occurs during the hard callus stage?

Answer 9

Cartilage is converted to Woven bone

• Occurs in a long bone fracture: endochondral and membranous bone formation
• Increased rigidity
• Known as SECONDARY BONE HEALING
• There is an obvious callus

Question 10

What occurs in the remodelling stage?

Answer 10

Woven bone converted to lamellar bone.

The medullary canal is reconstituted

Question 11

What could cause Delayed Union of a fracture?

Answer 11

• High energy injury
• Instability
• Infection
• Steroids & immunosuppressants
• Smoking
• Warfarin
• NSAIDs
• Ciprofloxacin

Question 12

What can you do when a bone fracture fails/delays healing?

Answer 12

A different fixation
Dynamisation
Bone Grafting

Question 13

Soft callus management

Answer 13

-Replace the cartilage- through Demineralised bone matrix (take bone and remove cartilage from it).
Either when first treated or when fracture has healed
- OR BONE : graft and bone substitutes: either straight from the patient or from bone bank

Question 14

What law does remodelling follow

Answer 14

Wolff’s law

Question 15

What is a non-union and what causes it?

Answer 15

Failure to heal

Aetiology:

• failure of fibro cartilage calification
• Instability : too much osteoclasis (surgical destruction of bone tissue)
• Abundant Callus formation

Question 16

What is the presentation of a non-union?

Answer 16

• Pain and tenderness
• Persistant fracture line
• Sclerosis

Question 17

which type of bone is more biologically active?

Answer 17

Cancellous bone

Question 18

which type of bone is responsible for longitudinal growth?

Answer 18

cancellous bone

Question 19

Aetiology of a fracture

Answer 19

• High energy transfer in normal bones
• Repetitive stress in normal bones= stress fracture
• Low energy transfer in abnormal bones leads to osteoporosis, osteomalacia , other bone disorders

Question 20

what does wolfs law state?

Answer 20

bone in a healthy person or animal will adapt to the loads under which it is placed. If loading on a particular bone increases, the bone will remodel itself over time to become stronger to resist that sort of loading.

Question 21

Types of fracture

Answer 21

•May be a crack, break, split, crumpling, buckle