Bone growth and fracture healing

Question 1

Where are the epiphyseal growth plate in long bones?

Answer 1

Below the metaphysis and spongy bone at the ends of the bones

Question 2

What does cortical bone do?

Answer 2

Resist bending and torsion

Less active, slow growing

Question 3

What does cancellous bone do?

Answer 3

Lies in metaphysis and resists shock and compression

More active and growing

Question 4

What is a fracture?

Answer 4

Break in structural continuity of bones

Question 5

Why might bones structure fail?

Answer 5

High energy transfer

Repeated stress

Question 6

Does bone repair leave scars?

Answer 6

No

Question 7

What are the 4 stages of bone repair?

Answer 7

Inflammation, soft callus, hard callus, bone remodelling

Question 8

Describe the inflammatory stage of bone repair.

Answer 8

Haematoma and fibrin clot released into area
Platelets, monocytes, neurtophils, macrophages released
Cell death release lysosomal enzymes to recruit repair cells (Fibroblasts, osteoprogenitor cells)
Angiogenesis

Question 9

What are platelet concentrates used for?

Answer 9

Releases VEGF, PDGF. TGF-b, IGF

Brings in cells and blood vessels to improve angiogenesis following tissue disruption

Question 10

Describe the soft callous stage.

Answer 10

Lays down collagen matrix to provide some stability

Remains in place until bone fragments are back in contact using cartilaginous and fibrous mass

Question 11

How do we aid the soft callus stage?

Answer 11

Replace cartilage with demineralised bone matrix (DMB)

Use bone graft or sub

Question 12

What is autogenous cancellous bone graft?

Answer 12

Gold standard
Osteoconductive (Bone can grow through it)
Osteoinductive (Stimulates bone growth)

Question 13

Describe the hard callus stage.

Answer 13

Conversion of cartilage to woven bone

Question 14

What is Wolf’s law?

Answer 14

When you load a bone in any direction it will strengthen to resist that

Question 15

Describe the bone remodelling stage.

Answer 15

Conversion of woven bone to lamellar bone

Bone responds to wolf’s law

Question 16

What is an important characteristic of woven bone?

Answer 16

Can respond to load from any direction

Question 17

What may cause delayed union?

Answer 17

High energy injury
Infection
Ciprofloxacin
Instability
Smoking
Warfarin
Steroids or immune suppression

Question 18

How may we respond to delayed union?

Answer 18

Change the way the fracture is healed

Alter, add or remove treatments like plates, bone grafting, nails etc.

Question 19

What may cause non union?

Answer 19

Instability
Failure of fibrocartilage to form bone
No bridging of segments of bone
Sclerosis