Small Animal Ortho: Bone Healing

Question 1

What are the factors that affect bone healing?

Answer 1

Age of animal
location of fracture
presence of necrotic debris
vascularity
stability
distance b/w fragments
degree of immobilization
fracture type
degree of post reduction opposition
degree of local trauma
degree of bone loss
type of bone involved

Question 2

How does infection affect fracture healing?

Answer 2

will slow/retard the healing process

Question 3

How does local malignancy affect fracture healing?

Answer 3

they heal slower than normal but can still heal

Question 4

How do corticosteroids affect fracture healing?

Answer 4

inhibit healing
the inhibit the differentiation of osteoblasts from mesenchymal cells and decrease the rate of synthesis of major components of the bone matrix

Question 5

How does the fracture being stable vs. unstable affect callus formation?

Answer 5

if stable and gap small vessels & osteoblasts directly cross gap & deposit= minimal callus

if unstable and gap large, vessels cross gap will be torn & callus will be large

Question 6

What are the 2 ways that fractures can heal?

Answer 6

Stable and unstable conditions

Question 7

What are stable fracture conditions?

Answer 7

direct opposition of bone
results in direct/primary bone healing

Question 8

What are unstable fracture conditions?

Answer 8

connective tissue, fibrocartilage then bone
results in indirect or secondary bone healing

Question 9

What are the 4 stages of fracture healing?

Answer 9

Coagulation
Inflammation
Granulation
Maturation

Question 10

What is the coagulation step of bone healing?

Answer 10

hematoma forms at fracture gap

Question 11

What is the inflammation step of bone healing?

Answer 11

neutrophils, macrophages, osteoclasts gather @ fracture site to clean it up

Question 12

What is the granulation step of bone healing?

Answer 12

callus forms by:
fibroblasts producing fibrous tissue
chondrocytes produce fibrocartilage
osteoblasts produce bone

Question 13

What is the maturation step of bone healing?

Answer 13

remodeling
modeling
osteoclast/osteoblasts

Question 14

What is indirect/secondary bone healing?

Answer 14

occurs through the formation of a callus & subsequent remodeling

Question 15

What type of bone is involved in indirect/secondary bone healing and what is it?

Answer 15

Woven bone: characterized by a haphazard organization of collagen fibers & is mechanically weak

Question 16

When is indirect/secondary bone healing preferred?

Answer 16

Good blood supply
large gaps > 1mm
not rigidly stable

Question 17

What is direct/primary bone healing?

Answer 17

reestablishment of the cortex w/o the formation of a callus

Question 18

What type of bone is involved in direct/primary bone healing and what is it?

Answer 18

lamellar bone: characterized by a regular parallel alignment of collagen into sheets & is mechanically strong

Question 19

When is direct/primary bone healing preferred?

Answer 19

Little to no gaps (less that 1mm)
good blood supply
stable conditions

Question 20

What is fracture assessment scoring?

Answer 20

method of selecting appropriate repair technique by considering 3 factors. The higher the score the more factors that favor wound healing

Question 21

What are the 3 factors to consider in fracture scoring?

Answer 21

Mechanical: fracture factors
Biological: patient factors
Clinical: owner factors pain tolerance of P

Question 22

What occurs in areas < 200 micrometers apart?

Answer 22

hematoma gap
little remodeling
blood vessels & mesenchymal cell
osteoblasts deposit lamellar bone

Question 23

What occurs in areas > 200 micrometers but < 1 mm

Answer 23

hematoma gap
later remodeling
blood vessels & mesenchymal cell
osteoblasts deposit woven bone haphazardly