(Muscskelint) Bone Healing

Front 1

This type of bone has randomly oriented collagen fibers, and can be seen in pathological conditions

Back 1

Woven Bone

Front 2

This type of bone has collagen fibers arranged in parallel layers. It is normal adult bone

Back 2

Lamellar Bone

Front 3

What are two synonyms for cancellous bone?

Back 3

Trabecular or spongy bone

Front 4

What percentage of bone matrix is made up of the organic component?

Of the portion that is organic, what portion is made up of collagen?

Back 4

The organic component makes up 35% of the matrix. Of this 35%, 90% is collagen

Front 5

What type of collagen do you see in the organic bone matrix?

Back 5

Type 1

Front 6

Where are osteoclasts located in the cutting cone?

Back 6

At the front

Front 7

Where are osteoblasts located in the cutting cone?

Back 7

At the back of the cone

Front 8

What is the mechanism by which long bones grow in width?

Back 8

Intramembranous (Periosteal)

Front 9

(T/F) Periosteal bone formation requires a cartilage anlage?

Back 9

False

Front 10

What is the mechanism by which bones grow in length?

Back 10

Endochondral ossification

Front 11

When it comes to endochondral ossification, is the zone of hypertrophy low or high in oxygen tension?

Back 11

Low oxygen tension

Front 12

When it comes to endochondral ossification what does ossification do to the oxygen tension?

Back 12

Increases it

Front 13

What are two prerequisites for bone healing?

Back 13

1. Adequate blood supply
2. Adequate mechanical stability

Front 14

What are the three important blood supplies in long bones (according to the lecturer)?

Back 14

1. Nutrient artery
2. Periosteal vessels
3. Metaphyseal vessels

Front 15

This blood vessel is mainly the major blood supply of the diaphyseal cortex. It forms medullary arteries up and down the bone.

Back 15

Nutrient artery

Front 16

These vessels arise from the capillary-rich periosteum They supply 15-20% of the cortex.

They are capable of supplying a much greater portion of the cortex in the event of injury

Back 16

Periosteal vessels

Front 17

When doing bone surgery, why is it so important to be careful to avoid stripping the periosteum?

Back 17

It supplies most of the capillary buds during fracture healing

Front 18

These vessels arise from periarticular vessels. They penetrate the the cortex in the metaphyseal region and anastomose with the medullary blood supply.

Back 18

Metaphyseal vessels

Front 19

Following a fracture, blood flow is increased substantially to the fracture site.

When does the blood flow peak?

Back 19

Two weeks after the fracture

Front 20

Following a fracture, after this length of time loading and interfragmentary motion promotes greater callus formation.

Back 20

After one month

Front 21

What is a hypertrophic nonunion?

Back 21

When inadequate stabilization leads to excessive deformation at the fracture site interrupting tissue differentiation of bone.

Front 22

3 stages of fracture healing:

Back 22

Inflammation, repair, remodeling

Front 23

What happens immediately after a fracture?

Back 23

Tissue disruption results in hematoma at the fracture site

This provides a scaffold for migration of repair cells

Front 24

Why might a broken limb look worse on an X-ray down the road after the initial injury?

Back 24

As part of the inflammatory process, local vessels thrombose causing bony necrosis at the edges of the fracture, making it look worse.

Front 25

During the bone repair process, once inflammation subsides, fibroblasts and chondrocytes start producing a new matrix. What is the term for this?

Back 25

Callus formation

Front 26

What is the oxygen tension of an intramedullary callus at the center of a fraction site?

Back 26

Low oxygen tension

Front 27

What type of ossification allows a soft callus to become a hard callus?

Back 27

Endochondral ossification

Front 28

What is meant by a fracture being radiographically healed? What about clinically healed?

Which is better?

Back 28

Radiographically healed means the fracture is healed on the X-ray. (Patient may still be in pain).

On the other hand, when a patient has no pain, it is clinically healed.

It is better to have a wound that is radiographically healed and the patient be in pain, than vice versa because that means the rods inserted are doing all the work (not the bone)

Front 29

Is this direct or indirect?

Mechanism of healing where there is no motion at the fracture site?

Back 29

Direct bone healing

Front 30

Does direct bone healing involve a callus?

Back 30

No!

Front 31

Which is faster, direct or indirect healing?

Back 31

Indirect healing

Front 32

(T/F) Direct bone healing relies on a cutting cone to cross the fracture site?

Back 32

True

Front 33

What is contact healing?

Back 33

When direct contact between the fracture ends allows healing with lamellar bone immediately

Front 34

What is gap healing?

Back 34

When gaps less than 200-500 microns are filled with woven bone that is remodeled into lamellar bone.

Notes go on to say that larger gaps rely on indirect bone healing.

Front 35

Compact and are two types of which healing?

A. Direct Healing
B. Indirect Healing

Back 35

A. Direct bone healing

Front 36

Under this type of bone healing, periosteal calluses and medullary calluses are bridged to re-establish structural continuity

Back 36

Indirect bone healing

Front 37

This growth factor promotes proliferation and differentiation of mesenchymal precursors for osteoblasts,osteoclasts, and chondrocytes.

It stimulates both endochondral and intermembranous bone formation.
Also, it induces synthesis of cartilage specific proteoglycans and type II collagen.

Back 37

Transforming growth factor

Front 38

The growth factor induces cell differentiation, promotes endochondral ossification, and regulates extracellular matrix production.
It is used clinically (though expensive)

Back 38

Bone morphogenetic proteins

Front 39

This growth factor has both acidic and basic forms. It increases proliferation of chondrocytes and osteoblasts, it enhances callus formation, and one variant even stimulates angiogenesis.

Back 39

Fibroblast Growth Factor (FGF)

FGF-2 stimulates angiogenesis

Front 40

This growth factor is a dimer of two genes. It stimulates bone cell growth. It increases type I collagen synthesis by increasing number of osteoblasts.

Back 40

Platelet-Derived Growth Factor

Front 41

This growth factor, when produced in the liver is stimulated by growth hormone. It stimulates bone collagen and matrix formation.
It also inhibits bone collagen degradation

Back 41

Insulin-like growth factor (specifically IGF-1)

Front 42

What do the following have in common?

IL-1, IL-4, IL-6, IL-11, GM-CSF, TNF

Back 42

They all stimulate bone resorption

Front 43

Why cytokine is most potent for bone resorption?

Back 43

IL-1

Front 44

What is the hypothesis for why post-menopausal women get osteoporosis?

Back 44

Lack of estrogen leads to an increase in IL-1 and IL-6.

This leads to increased bone reabsorption. How? Via stimulation of RANK-RANKL which leads to osteoclast differentiation and activation.

Front 45

Which growth factors / cytokines have the lowest bone formation activity and highest bone resorption activity?

Back 45

IL-1, TNF (alpha and beta)

Front 46

Which growth factors / cytokines have the highest bone formation activity and lowest bone resorption activity?

Back 46

IGF-1, IGF-2, FGF

Front 47

What do prostaglandins of the E series do (two things)?

Back 47

Stimulate osteoblastic bone formation and inhibit activity of isolated osteoclasts.

Front 48

What do leukotrienes do (two things)?

Back 48

Stimulate osteoblastic bone formation and enhance the capacity of isolated osteoclasts to form resorption pits.

Front 49

This hormone inhibits calcium absorption from the gut causes increased PTH and therefore increased osteoclastic bone resorption.

Back 49

Glucocorticoids

Front 50

What do thyroid hormones do?

Back 50

Stimulate osteoclastic bone resorption

Front 51

Name four anatomic factors that influence fracture healing:

Back 51

1.Injury to soft tissue
2. Interruption of local blood supply
3. Interposition of soft tissue at fracture site
4. Bone death caused by radiation, thermal, or chemical burns or infection

Front 52

How does malnutrition lead to a decrease in bone fracture healing?

Back 52

Caused reduction in activity and proliferation of osteochondral cells. This leads to a decreased callus formation

Front 53

How does cigarette smoking impact bone healing?

Back 53

Smoking inhibits osteoclasts.

Nicotine causes vasoconstriction which diminishes blood flow to fracture site

Front 54

How does diabetes mellitus affect bone healing?

Back 54

Associated with collagen defects including:
Decreased collagen synthesis
Defective cross-linking
Alterations in collagen sub-type ratios

Front 55

This technology used for bone healing modulates signal transduction, increases gene expression, increases torsional strength of calluses, and increases blood flow to the bone.

Back 55

Ultrasound

Front 56

In which cohort (yes- I used the word cohort) has ultrasound been shown to be particularly helpful in speeding up bone healing time?

Back 56

Smokers