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
2
Q
What extracellular matrix are responsible for Bone composition
A
- Organic + water
- Inorganic
3
Q
Where do Osteoprogenitor cells directly come form?
A
MSC’s
mesenchymal stem cell
4
Q
Define Osteoblasts
A
Produce bone
5
Q
Define Osteoclasts
A
Remove bone
6
Q
Define Osteocytes
A
resident support
7
Q
What cells used in bone composition are used during formation and when there is a problem
A
Osteocytes
- resident support
8
Q
What part of the Extraellular Matrix is part of Bone composition
A
Inorganic - 65%
Organic and water - 35%
9
Q
What type of collagen makes up 90% of Organic / water in the ECM
A
type 1
10
Q
Osteocalcin, Osteonectin, Proteoglycans, Glycosaminoglycans and lipids make up what portion of the ECM
A
Organic / water
11
Q
Mostly hydroxyapatite and some calcium phosphate make up what portion of the ECM
A
Inorganic
12
Q
Which part of the bone is responsible for regenerative cells are stored / ready for when there is a problem
A
Metaphysis
13
Q
What is number 1
A
Epiphysis
14
Q
What is number 2
A
Metaphysis
15
Q
What is number 3
A
Diaphysis
16
Q
What is number 4
A
Articular Cartilage
17
Q
What is number 5
A
Spongy Bone
18
Q
What is number 6
A
Epiphyseal plate
19
Q
What is number 7
A
Medullary cavity
20
Q
What is number 8
A
Endosteum
21
Q
What is number 9
A
Peristeum
22
Q
Define Direct (Primary) Fracture Healing
A
Osteonal reconstruction
- Requires rigid internal fixation
- less than 2%
- Minimal or no fracture gap
23
Q
Define Indirect (Secondary) Fracture Healing
A
Intermediate callus formation
- Direct bone formation (intermembranous)
- Endochondral ossification
24
Q
What type of Fracture healing Is defined as
- Intermediate callus formation
A
indirect - secondary
25
What type of Fracture healing Is defined as
- Osteonal reconstruction
Direct - primary
26
What type of Fracture healing Is defined as
- Requires rigid internal fixation
(less than 2% strain)
Direct - primary
27
What type of Fracture healing Is defined as
- Minimal or no fracture gap
Direct - primary
28
What type of Fracture healing Is defined as
- Direct bone formation (inter membranous)
Indirect - secondary
29
What type of Fracture healing Is defined as
- Endochondral ossification
- within the cartilage turing into bone
indirect - secondary
30
Does and increases or decrease strain decreases the ability of the bone to heal by direct bone healing + some secondary healing
increase in strain
31
Define strain in reference to fracture gap length
Change in length / original strength
- described as a percentage
32
What percent of strain is caused by granulation tissue withstood by tissue
100% strain
33
What percent of strain is caused by cartilage withstood by tissue
10% strain
34
What percent of strain is caused by Bone (osteoblasts) withstood by tissue
2% strain
35
Define Contact healing related to Direct healing
- **Gaps less than 300 microns**
- Osteons (cutting cones)
- 50-80 microns/day
36
Define Gap healing related to Direct healing
- **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
37
What type of healing is this can how can we tell?
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)
38
What type of cells produce bone
osteoblasts
39
What does this image describe?
Formation of cutting cones - formation of new osteons
- Intra-cortical remodeling
40
What type of healing is described by this image?
Direct (primary) healing
- Gap healing
41
What are the three requirements for Direct (Primary) Healing
Rigid fixation
Adeqate reduction
Sufficient blood supply
42
Why is Rigid fixation requred for Direct (Primay) healing?
decrease inter-fragmentary strain
- allow cutting cones to work = stability = good
43
Why is Adequate Reduction requred for Direct (Primay) healing?
put two pieces together ad stabilize the area
- only possible with simple fractures
44
What is the most common type of fracture healing
- even in repaired fractures
Indirect (secondary) healing
45
In indirect (secondary) healing what is the result of enhanced motion?
More motion = more callus
(some is good = heals faster and better)
46
What type of bone healing is described as:
- Ibhibited by rigid stabilization
- Requires callus formation
- Enhanced by motion
Indirect (secondary) healing
47
What type of bone healing is described in this image?
Indirect (secondary) healing
- Pinned fracture callus formation
48
In Indirect (secondary) healing what are the 4 general phases of fracture healing
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
What is the only accurate phase in indirect healing phases?
1. hematoma formation (inflammation) phase
50
What are the four stages of inidirect (secondary) bone healing that is important in this class
1. Hematoma formation/ inflammation
2. Intramembrnaous bone formation
3. Chondrogenesis
4. Endochondral ossification
51
What phase in bone healing do we notice
- release of inflammatory cells and mediators
- Bone morphogenetic protein (BMP)
- Other TGF-B proteins
1. Hematoma formation/inflammation
52
In what stage of bone healing do we notice
- Very similar to metaphyseal growth plate
- transforming growth factor B
4. Endochondral ossification
53
What type of fracture healing is described by this image?
Indirect fracture healing
- Soft callus
54
What type of fracture healing is described in this image?
Indirect fracture healing
- Hard callus
Recruit osteoblasts = bone formation
55
What stage of the 4 phases in fracture healing is described in this image?
Hematoma formation/ inflammation
56
What stage of the 4 phases in fracture healing is described in this image?
Intramembranous bone formation
57
What stage of the 4 phases in fracture healing is described in this image?
Chondrogenesis
58
What stage of the 4 phases in fracture healing is described in this image?
Endochondral ossification
59
Fracture healing is ?
limited or continued
Continued
60
Which is faster for bone healing?
Indirect or direct bone healing
indirect bone healing is faster
61
What type of fracture healing uses rigid stabilization
- Ex: Bone plate
Direct fracture healing
62
What type of fracture healing required less rigid fixation with callus formation
- EX: pins/wires, interlocking nail, external fixation, LCP's
Indirect fracture healing
63
To avoid fracture complications what are 4 things you need to understand?
1. bone healing
2. bone blood supply
3. growth fracures
4. Surgical principles
64
Define fracture nonunions
- ALL evidence of osteogenic activity at fracture site has ceased
- fracture union NOT possible without surgical intervention
- Weber-cech classification
65
What are the two Weber-Cech classification?
- Viable (Vascular)
- Nonviable (Avascular)
66
What type of nonunion is described as:
- Abundant callus but NOT bridging the fracture site
Viable - Hypertrophic nonunion
67
What type of nonunion is described as:
- Called the elephant foot
Viable - Hypertrophic nonunion
68
What type of nonunion is described as:
Viable - Hypertrophic nonunion
69
What are the main causes of Viable - Hypertrophic nonunion
- Inadequate stabilization
- Premature weight-bearing
- Too much activity of patient
70
What is described as this image?
Hypertrophic Nonunion
71
What type of nonunion is described as:
- Mild callus but NOT bridging the fracture site
Viable - Mildly hpertonic
72
What type of nonunion is described as:
- Called the horses foot
Viable - Mildly hypertrophic
73
What are the causes of viable- Mildly hypertonic nonunion
- Inadequate stabilization usually due to implant failure
- Examples are: Plate breaks, screw pulls out
74
What type of nonunion is described as:
Mildly Hypertonic
the screws in the image are due to active / over active animal
75
What type of nonunion is described as:
- No callus, just fibrous tissue and blood vessels joining ends
Viable - Oligotrophic
76
What type of nonunion is described as:
- See rounding of fracture edges, resoprtion of bone and shortening of fragments
Viable - Oligotrophic
77
What are causes of Viable - Oligotrophic nonunion
- Displacement of fracture fragments
- inadequate apposed fragments
78
What type of nonunion is described as:
Viable - Oligotrophic
- On the image notice the gap here and rounding of the fracture edges
79
What type of nonunion is described as:
- Intermediate fragments of fracture heal to one main fragment and not the other
Nonviable - Dystrophic nonunion
80
What are causes of Nonviable Dystrophic nonunion
- Poor blood supply on non-healing side
- instability on avascular side
- More comon in older animals with poorer blood supply
81
What type of nonunion is described as:
Nonviable - Dystrophic nonunion
82
What type of nonunion is described as:
- Fragments have no blood supply and cannot heal to any of main fragments
Nonviable - Necrotic nonunion
83
What type of nonunion is described as:
- The classical "sequestrum"
- Avascularity of fragment can lead to implant loosening
Non-viable necrotic nonunion
84
What are the causes of Nonviable Necrotic Nonunion
- Poor blood supply
- Infection at the fracture site
- BUT DOES NOT HAVE TO BE AN INFECTION
85
What type of nonunion is described as:
Nonviable necrotic nonunion
86
What type of nonunion is described as:
- Large defect - even if ends have blood supply, they cannot bridge bone
Nonviable defect nonunion
87
What causes nonviable defect nonunion?
Massive loss of bone at fracture site
88
What type of nonunion is described as:
-
Nonviable Defect Nonunion
89
What type of nonunion is described as:
- End result of other 3 nonviable nonunions
- uncommon
Nonviable atrophic nonunion
90
What type of nonunion is described as:
- The most difficult cases to Treat
Nonviable atrophic nonunion
91
What type of nonunion is described as:
Nonviable Atrophic Nonunion
92
What are common causes of nonunion fracture healing
- Infection
- Ischemia
- Distraction of bone ends
- Excessive compression of bone ends
- Interposition of oft tissue at fracture
- Improper implant fixation
- systemic factors
93
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
Nonunio fracture healing
94
What be seen on a radiographic nonunion?
- Fracture gap
- No activity at fracture ends
- Obliteration of marrow cavity
- Osteopenia of surrounding bone
- If callus present - does not bridge fracture gap
95
How do treat a nonunion fracture
- Rigid stabilization of fracture
- Enhancing blood supply (bone grafting)
- treat underlying cause of nonunion
96
Give examples of underlying nonunion causes we notice during treatment
- Infection (contaminated wounds in open fractures are 5x more likley to develop complication)
- fracture gaps
- make sure animal is metabolically healthy
97
What type of fracure is described as:
Malunions
98
What type of fracure is described as:
- Fracture that heals in a non-healing anatomic position
Malunions
99
What are causes of Malunions fracture healing?
- Untreated fracture
- Improperly treated fracture
- Premature excessive weight bearing on fracture
- Complicated owners
100
What are the clinical results are Malunions
- Angular limb deformities
- Limb Shortening
- Gait Abnormalities
- Degenerative Joint Disease
101
What type of fracure is described as:
Delayed Union
102
What type of fracure is described as:
- Fracture not healed in expected time
- Considering pateint and fracture enviornment
Delayed Union
103
Describe how blood is normally supplied to the bone
- Nutrient artery to bone marrow
- Periosteal vessles
- Epiphyseal + Metaphyseal vessels
- Differences exist depending on growth versus maturity phase
104
What percent of blood does the nutrient artery provide blood supply to the bone?
80-85% of supply
105
Right after an injury what supplies early periosteal callus to the bone?
Extraosseous
- medually supply eventually takes back over the blood supply
106
Define Autogenous
within same individuals
107
Define Allograft
Different individuals of the same species
108
Define Xenograft
Different individuals in different species
109
What are the 4 O's of Bone grafting?
Osteogenesis
Osteoconduction
Osteoinduction
Osteopromotion
110
What is defined as:
- Osteblasts that survive trasnfer
- very few survive
Osteogenesis
111
What is defined as:
- Graft acts as scaffold in which new bone is laid down
Osteoconduction
112
What is defined as:
- Graft induces cells to promote new bone
- Bone Morphogenetic Protein (BMP)
Osteoinduction
113
What is defined as:
- Material that enchanes regeneration of bone
- Platelet-rich plasma
Osteopromotion
114
Define Cancellous type bone graft
From trabecular bone
- Works by the O's of grafting
115
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
Cancellous bone graft
116
When are indications that bone grafts may be needed?
- Any orthopedic fracture or arthrodesis
- Infected fractures
- Delayed / nonunions
- Bone loss - cysts , fractures
- Limb sparing for bone tumors
117
What are important things to keep in mind when Harvesting a cancellous bone graft
- 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
Where are the most common place to prepare a donor site for harvesting cancellous bone graft
Ilial wing
Proximal tibia
Humerus
Distal femur
