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2025 - Intro to Surgery 737A > Exam 3: Lecture 24 - Mechanisms of Bone Healing > Flashcards

Exam 3: Lecture 24 - Mechanisms of Bone Healing Flashcards

1
Q

What cells are responsible for Bone composition

A
  • Osteoprogenitor cells
  • Osteoblasts
  • Osteoclasts
  • Osteocytes
  • Bone Lining
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2
Q

What extracellular matrix are responsible for Bone composition

A
  • Organic + water
  • Inorganic
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3
Q

Where do Osteoprogenitor cells directly come form?

A

MSC’s

mesenchymal stem cell

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4
Q

Define Osteoblasts

A

Produce bone

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5
Q

Define Osteoclasts

A

Remove bone

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6
Q

Define Osteocytes

A

resident support

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7
Q

What cells used in bone composition are used during formation and when there is a problem

A

Osteocytes
- resident support

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8
Q

What part of the Extraellular Matrix is part of Bone composition

A

Inorganic - 65%

Organic and water - 35%

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9
Q

What type of collagen makes up 90% of Organic / water in the ECM

A

type 1

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10
Q

Osteocalcin, Osteonectin, Proteoglycans, Glycosaminoglycans and lipids make up what portion of the ECM

A

Organic / water

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11
Q

Mostly hydroxyapatite and some calcium phosphate make up what portion of the ECM

A

Inorganic

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12
Q

Which part of the bone is responsible for regenerative cells are stored / ready for when there is a problem

A

Metaphysis

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13
Q

What is number 1

A

Epiphysis

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14
Q

What is number 2

A

Metaphysis

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15
Q

What is number 3

A

Diaphysis

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16
Q

What is number 4

A

Articular Cartilage

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17
Q

What is number 5

A

Spongy Bone

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18
Q

What is number 6

A

Epiphyseal plate

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19
Q

What is number 7

A

Medullary cavity

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20
Q

What is number 8

A

Endosteum

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21
Q

What is number 9

A

Peristeum

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22
Q

Define Direct (Primary) Fracture Healing

A

Osteonal reconstruction
- Requires rigid internal fixation
- less than 2%
- Minimal or no fracture gap

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23
Q

Define Indirect (Secondary) Fracture Healing

A

Intermediate callus formation
- Direct bone formation (intermembranous)
- Endochondral ossification

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24
Q

What type of Fracture healing Is defined as
- Intermediate callus formation

A

indirect - secondary

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25
Q

What type of Fracture healing Is defined as
- Osteonal reconstruction

A

Direct - primary

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26
Q

What type of Fracture healing Is defined as
- Requires rigid internal fixation
(less than 2% strain)

A

Direct - primary

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27
Q

What type of Fracture healing Is defined as
- Minimal or no fracture gap

A

Direct - primary

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28
Q

What type of Fracture healing Is defined as
- Direct bone formation (inter membranous)

A

Indirect - secondary

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29
Q

What type of Fracture healing Is defined as
- Endochondral ossification
- within the cartilage turing into bone

A

indirect - secondary

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30
Q

Does and increases or decrease strain decreases the ability of the bone to heal by direct bone healing + some secondary healing

A

increase in strain

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31
Q

Define strain in reference to fracture gap length

A

Change in length / original strength

  • described as a percentage
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32
Q

What percent of strain is caused by granulation tissue withstood by tissue

A

100% strain

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33
Q

What percent of strain is caused by cartilage withstood by tissue

A

10% strain

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34
Q

What percent of strain is caused by Bone (osteoblasts) withstood by tissue

A

2% strain

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35
Q

Define Contact healing related to Direct healing

A
  • Gaps less than 300 microns
  • Osteons (cutting cones)
  • 50-80 microns/day
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36
Q

Define Gap healing related to Direct healing

A
  • Gap less than 1 mm
  • Blood vessels and connective tissue form
  • osteoblasts deposit perpendicular lamellar bone in gao
  • Cutting cones traverse fracture place
  • Lamellar bone becomes longitudinally oriented
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37
Q

What type of healing is this can how can we tell?

A

Direct (Primary) healing
- contact healing

We can tell because of cutting cones moving across the fracture
(indicated by the black line to the left on the black and white image)

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38
Q

What type of cells produce bone

A

osteoblasts

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39
Q

What does this image describe?

A

Formation of cutting cones - formation of new osteons

  • Intra-cortical remodeling
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40
Q

What type of healing is described by this image?

A

Direct (primary) healing
- Gap healing

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41
Q

What are the three requirements for Direct (Primary) Healing

A

Rigid fixation
Adeqate reduction
Sufficient blood supply

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42
Q

Why is Rigid fixation requred for Direct (Primay) healing?

A

decrease inter-fragmentary strain
- allow cutting cones to work = stability = good

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43
Q

Why is Adequate Reduction requred for Direct (Primay) healing?

A

put two pieces together ad stabilize the area
- only possible with simple fractures

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44
Q

What is the most common type of fracture healing

  • even in repaired fractures
A

Indirect (secondary) healing

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45
Q

In indirect (secondary) healing what is the result of enhanced motion?

A

More motion = more callus

(some is good = heals faster and better)

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46
Q

What type of bone healing is described as:

  • Ibhibited by rigid stabilization
  • Requires callus formation
  • Enhanced by motion
A

Indirect (secondary) healing

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47
Q

What type of bone healing is described in this image?

A

Indirect (secondary) healing

  • Pinned fracture callus formation
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48
Q

In Indirect (secondary) healing what are the 4 general phases of fracture healing

A
  1. Hematoma formation (inflammation) phase
  2. Sof callus formation (proliferative) phase
  3. Hard callus formation (maturing or modeling) phase
  4. Remodeling phase

some references combine 2 and 3 = reparative phase

49
Q

What is the only accurate phase in indirect healing phases?

A
  1. hematoma formation (inflammation) phase
50
Q

What are the four stages of inidirect (secondary) bone healing that is important in this class

A
  1. Hematoma formation/ inflammation
  2. Intramembrnaous bone formation
  3. Chondrogenesis
  4. Endochondral ossification
51
Q

What phase in bone healing do we notice

  • release of inflammatory cells and mediators
  • Bone morphogenetic protein (BMP)
  • Other TGF-B proteins
A
  1. Hematoma formation/inflammation
52
Q

In what stage of bone healing do we notice
- Very similar to metaphyseal growth plate
- transforming growth factor B

A
  1. Endochondral ossification
53
Q

What type of fracture healing is described by this image?

A

Indirect fracture healing

  • Soft callus
54
Q

What type of fracture healing is described in this image?

A

Indirect fracture healing
- Hard callus

Recruit osteoblasts = bone formation

55
Q

What stage of the 4 phases in fracture healing is described in this image?

A

Hematoma formation/ inflammation

56
Q

What stage of the 4 phases in fracture healing is described in this image?

A

Intramembranous bone formation

57
Q

What stage of the 4 phases in fracture healing is described in this image?

A

Chondrogenesis

58
Q

What stage of the 4 phases in fracture healing is described in this image?

A

Endochondral ossification

59
Q

Fracture healing is ?

limited or continued

60
Q

Which is faster for bone healing?

Indirect or direct bone healing

A

indirect bone healing is faster

61
Q

What type of fracture healing uses rigid stabilization
- Ex: Bone plate

A

Direct fracture healing

62
Q

What type of fracture healing required less rigid fixation with callus formation
- EX: pins/wires, interlocking nail, external fixation, LCP’s

A

Indirect fracture healing

63
Q

To avoid fracture complications what are 4 things you need to understand?

A
  1. bone healing
  2. bone blood supply
  3. growth fracures
  4. Surgical principles
64
Q

Define fracture nonunions

A
  • ALL evidence of osteogenic activity at fracture site has ceased
  • fracture union NOT possible without surgical intervention
  • Weber-cech classification
65
Q

What are the two Weber-Cech classification?

A
  • Viable (Vascular)
  • Nonviable (Avascular)
66
Q

What type of nonunion is described as:

  • Abundant callus but NOT bridging the fracture site
A

Viable - Hypertrophic nonunion

67
Q

What type of nonunion is described as:

  • Called the elephant foot
A

Viable - Hypertrophic nonunion

68
Q

What type of nonunion is described as:

A

Viable - Hypertrophic nonunion

69
Q

What are the main causes of Viable - Hypertrophic nonunion

A
  • Inadequate stabilization
  • Premature weight-bearing
  • Too much activity of patient
70
Q

What is described as this image?

A

Hypertrophic Nonunion

71
Q

What type of nonunion is described as:

  • Mild callus but NOT bridging the fracture site
A

Viable - Mildly hpertonic

72
Q

What type of nonunion is described as:

  • Called the horses foot
A

Viable - Mildly hypertrophic

73
Q

What are the causes of viable- Mildly hypertonic nonunion

A
  • Inadequate stabilization usually due to implant failure
  • Examples are: Plate breaks, screw pulls out
74
Q

What type of nonunion is described as:

A

Mildly Hypertonic

the screws in the image are due to active / over active animal

75
Q

What type of nonunion is described as:

  • No callus, just fibrous tissue and blood vessels joining ends
A

Viable - Oligotrophic

76
Q

What type of nonunion is described as:

  • See rounding of fracture edges, resoprtion of bone and shortening of fragments
A

Viable - Oligotrophic

77
Q

What are causes of Viable - Oligotrophic nonunion

A
  • Displacement of fracture fragments
  • inadequate apposed fragments
78
Q

What type of nonunion is described as:

A

Viable - Oligotrophic

  • On the image notice the gap here and rounding of the fracture edges
79
Q

What type of nonunion is described as:

  • Intermediate fragments of fracture heal to one main fragment and not the other
A

Nonviable - Dystrophic nonunion

80
Q

What are causes of Nonviable Dystrophic nonunion

A
  • Poor blood supply on non-healing side
  • instability on avascular side
  • More comon in older animals with poorer blood supply
81
Q

What type of nonunion is described as:

A

Nonviable - Dystrophic nonunion

82
Q

What type of nonunion is described as:

  • Fragments have no blood supply and cannot heal to any of main fragments
A

Nonviable - Necrotic nonunion

83
Q

What type of nonunion is described as:

  • The classical “sequestrum”
  • Avascularity of fragment can lead to implant loosening
A

Non-viable necrotic nonunion

84
Q

What are the causes of Nonviable Necrotic Nonunion

A
  • Poor blood supply
  • Infection at the fracture site
  • BUT DOES NOT HAVE TO BE AN INFECTION
85
Q

What type of nonunion is described as:

A

Nonviable necrotic nonunion

86
Q

What type of nonunion is described as:

  • Large defect - even if ends have blood supply, they cannot bridge bone
A

Nonviable defect nonunion

87
Q

What causes nonviable defect nonunion?

A

Massive loss of bone at fracture site

88
Q

What type of nonunion is described as:

-

A

Nonviable Defect Nonunion

89
Q

What type of nonunion is described as:

  • End result of other 3 nonviable nonunions
  • uncommon
A

Nonviable atrophic nonunion

90
Q

What type of nonunion is described as:

  • The most difficult cases to Treat
A

Nonviable atrophic nonunion

91
Q

What type of nonunion is described as:

A

Nonviable Atrophic Nonunion

92
Q

What are common causes of nonunion fracture healing

A
  • Infection
  • Ischemia
  • Distraction of bone ends
  • Excessive compression of bone ends
  • Interposition of oft tissue at fracture
  • Improper implant fixation
  • systemic factors
93
Q

The following clinical signs are a suggestion of?

  • Pain at the fracture site
  • lameness: Usually non-weight-bearing
  • Disuse atrophy of limb
  • Movement felt at fracture site
A

Nonunio fracture healing

94
Q

What be seen on a radiographic nonunion?

A
  • Fracture gap
  • No activity at fracture ends
  • Obliteration of marrow cavity
  • Osteopenia of surrounding bone
  • If callus present - does not bridge fracture gap
95
Q

How do treat a nonunion fracture

A
  • Rigid stabilization of fracture
  • Enhancing blood supply (bone grafting)
  • treat underlying cause of nonunion
96
Q

Give examples of underlying nonunion causes we notice during treatment

A
  • Infection (contaminated wounds in open fractures are 5x more likley to develop complication)
  • fracture gaps
  • make sure animal is metabolically healthy
97
Q

What type of fracure is described as:

98
Q

What type of fracure is described as:
- Fracture that heals in a non-healing anatomic position

99
Q

What are causes of Malunions fracture healing?

A
  • Untreated fracture
  • Improperly treated fracture
  • Premature excessive weight bearing on fracture
  • Complicated owners
100
Q

What are the clinical results are Malunions

A
  • Angular limb deformities
  • Limb Shortening
  • Gait Abnormalities
  • Degenerative Joint Disease
101
Q

What type of fracure is described as:

A

Delayed Union

102
Q

What type of fracure is described as:

  • Fracture not healed in expected time
  • Considering pateint and fracture enviornment
A

Delayed Union

103
Q

Describe how blood is normally supplied to the bone

A
  • Nutrient artery to bone marrow
  • Periosteal vessles
  • Epiphyseal + Metaphyseal vessels
  • Differences exist depending on growth versus maturity phase
104
Q

What percent of blood does the nutrient artery provide blood supply to the bone?

A

80-85% of supply

105
Q

Right after an injury what supplies early periosteal callus to the bone?

A

Extraosseous

  • medually supply eventually takes back over the blood supply
106
Q

Define Autogenous

A

within same individuals

107
Q

Define Allograft

A

Different individuals of the same species

108
Q

Define Xenograft

A

Different individuals in different species

109
Q

What are the 4 O’s of Bone grafting?

A

Osteogenesis
Osteoconduction
Osteoinduction
Osteopromotion

110
Q

What is defined as:

  • Osteblasts that survive trasnfer
  • very few survive
A

Osteogenesis

111
Q

What is defined as:

  • Graft acts as scaffold in which new bone is laid down
A

Osteoconduction

112
Q

What is defined as:

  • Graft induces cells to promote new bone
  • Bone Morphogenetic Protein (BMP)
A

Osteoinduction

113
Q

What is defined as:

  • Material that enchanes regeneration of bone
  • Platelet-rich plasma
A

Osteopromotion

114
Q

Define Cancellous type bone graft

A

From trabecular bone
- Works by the O’s of grafting

115
Q

What type of bone grafting is described as:

  • Bone grafting seperated from its blood supply
  • Few cells servive - Osteogenic cells
  • Mesenchymal stem cells are induced to form bone cell lines (Inductive Proteins)
  • Deposition new bone from osteoprogenitor cells
  • Resoprtion of nectrotic bone
A

Cancellous bone graft

116
Q

When are indications that bone grafts may be needed?

A
  • Any orthopedic fracture or arthrodesis
  • Infected fractures
  • Delayed / nonunions
  • Bone loss - cysts , fractures
  • Limb sparing for bone tumors
117
Q

What are important things to keep in mind when Harvesting a cancellous bone graft

A
  • Asepsis
  • Prepare surgical donor site in advance
  • Seperate surgical instruments
  • Minimize grafts exposure time to air
  • Keep in blood-soaked spongers
  • Debride graft area (Be careful not to create a fracture)
118
Q

Where are the most common place to prepare a donor site for harvesting cancellous bone graft

A

Ilial wing
Proximal tibia
Humerus
Distal femur

2025 - Intro to Surgery 737A (29 decks)

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