Lec 19: Mechanisms of Bone Healing Flashcards
1
Q
this type of fracture undergoes osteonal reconstructions, requires rigid internal fixation, less than 2% strain, and minimal or no fracture gap.
A
direct (primary)
2
Q
this type of fracture undergoes intermediate callus formation, direct bone formation (intramembranosus) and endochondral ossification
A
indirect (secondary)
3
Q
in direct bone formation (intramembranous) there is no _____ ______.
A
cartilaginous intermediate.
4
Q
the fracture gap length is the ___ in length / the original length
A
change
5
Q
fracture gap length is described as a _____
A
percentage
6
Q
granulation tissue can withstand ___% strain
A
100 - will survive through LOTS of stretching and movement
7
Q
cartilage can withstand __% strain
A
10
8
Q
bone can withstand __% strain
A
2
9
Q
____ healing occurs in gaps less than 300 microns
A
contact
10
Q
___ healing occurs in gaps less than 1 mm
A
gap
11
Q
osteons (cutting cones), cross the fracture plane from one fragment to the other in ____ healing
A
contact
12
Q
osteons (cutting cones) traverse the fracture plane in ____ healing
A
gap
13
Q
contact healing is ___
A
14
Q
direct healing consists of ___ healing and ___ healing.
A
contact ; gap
15
Q
in gap healing, blood vessels and ____ tissue form
A
connective
16
Q
osteblasts deposit _____ lamellar bone in the gap
A
perpendicular
17
Q
once once lamellar bone is deposited in gap healing, cutting cones are able to ____ the fracture plane
A
traverse
18
Q
once cutting cones traverse the fracture plane of the lamellar bone in gap healing, the lamellar bone becomes _____ oriented
A
longitudinally (this creates a stronger bone)
19
Q
osteons (cutting cones) can move at _____ microns/day in contact healing
A
50-80 ; they move slowly
20
Q
contact healing requires rigid ______ with a plate for direct healing to occur.
A
fixation
21
Q
direct (primary) healing requires what 3 things?
A
rigid fixation, adequate reduction, and sufficient blood supply
22
Q
what does rigid fixation do in primary healing?
A
decreases inter-fragmentary strain
23
Q
adequate reduction is only possible with…
A
simple fractures
24
Q
what is the most common type of fracture healing? (even in repaired fractures)
A
indirect (secondary) healing
25
indirect healing is enhanced by what?
motion
26
indirect healing is inhibited by what?
rigid stabilization
27
indirect healing requires ___ formation
callus
28
The 4 General Phases of Fracture Healing
1. ____ formation (inflammation phase)
2. soft callus formation (____ phase)
3. ____ formation (maturing or modeling phase)
4. ____ phase
hematoma ; proliferative ; hard callus ; remodeling
29
phase 1, hematoma formation/inflammation releases what types of cells along with mediators?
inflammatory cells
30
in the hematoma formation/inflammation phase, what important mediator is released?
BMP - bone morphogenetic protein (along with other TGF beta proteins)
31
phase 2 is ____
32
The 4 Specific Stages of Indirect Bone Healing
1. ____ formation/inflammation
2. ____ bone formation
3. ______
4. ______ ossification
hematoma ; intramembranous ; chondrogenesis ; endochondral
33
what is the endochondral ossification similar to?
metaphyseal growth plate
34
match the numbers with the phase of healing
1 - hematoma formation/inflammation
2 - intramembranous bone formation
3 - chondrogenesis
4 - endochondral ossification
35
which process is faster, direct bone healing or indirect bone healing?
INDIRECT
36
Direct fracture healing differs from indirect as it NEEDS
rigid stabilization of a bone plate
37
Indirect fracture healing differs from direct fracture healing as it requires....
LESS rigid fixation with callus formation
(ex: pins/wires, interlocking nail, external fixator - do not need to know these, just examples)
38
true or false: fracture complications can occur even if repair principles are adhered to
TRUE
39
to avoid fracture complications, we must understand
bone healing, bone blood supply, growth factors, and surgical principles
40
when all evidence of osteogenic activity at the fracture site has stopped, this is called...
fracture nonunion
41
true or false: fracture nonunion requires intervention for union to occur
TRUE
42
viable nonunion means that it is
vascular
43
nonviable nonunion means that it is
avascular
44
what is depicted in the image
viable hypertrophic nonunion
45
in viable, hypertrophic nonunions, an abundant ____ is notable but NOT bridging the fracture site
callus
46
another name for viable, hypertrophic nonunion
elephant foot
47
what are causes of viable hypertrophic nonunion (elephant foot)
1. inadequate stabilization
2. premature weight-bearing
3. too much activity of the patient
48
viable, mildly hypertrophic nonunion is also called
the horses foot
49
in viable, mildly hypertrophic nonunion, mild callus but ___ bridging the fracture site
NOT
50
causes of mildly hypertrophic nonunion:
inadequate stabilization usually due to implant failure (ex: plate breaks, screw pulls out)
51
what is depicted in the image?
viable, mildly hypertrophic nonunion (horses foot)
52
what is depicted in the image?
nonviable dystrophic nonunion
53
in this type of nonunion, intermediate fragments of fracture heal to 1 main fragment and not the other
nonviable dystrophic nonunion
54
what are causes of nonviable dystrophic nonunion?
1. poor blood supply on non-healing side
2. instability on avascular side
55
what nonunions are more common in older animals with poorer blood supply?
nonviable dystrophic nonunion
56
what is depicted in the image?
nonviable, necrotic nonunion
57
which type of nonunion fragments have NO blood supply and cannot heal to any main fragments?
nonviable necrotic nonunions
58
which type of nonunion represents the classical sequestrum?
nonviable necrotic nonunion
59
what can the avascularity of the fragment lead to in a nonviable necrotic nonunion?
implant loosening
60
what are the causes of a nonviable necrotic nonunion
1. poor blood supply
2. infection at the fracture site
61
what is depicted in the image?
nonviable defect nonunion
62
what is depicted in the image below?
nonviable atrophic nonunion
63
what is the end result of the three nonviable nonunions, extremely uncommon and one of the most difficult cases to resolve?
nonviable atrophic nonunion
64
overall causes of nonunions
infection, ischemia, distraction of bone ends, excessive compression of bone ends, interposition of soft tissue at the fracture, improper implant fixation, systemic factors
65
pain at the fracture site, lameness (usually non weight bearing), disuse atrophy of the limb, and movement felt at the fracture site are all clinical signs of _____.
nonunion
66
what signs will you see on radiography of a nonunion?
fracture gap, no activity at fracture ends, obliteration of marrow cavity, osteopenia of surrounding bone
and if there is a callus present, it does not bridge the fracture gap
67
Ways we can treat nonunions
1. ___ stabilization of fracture
2. Enhancing ____ _____. (bone grafting)
3. Treat _____ cause of nonunion
rigid ; blood supply ; underlying
68
what are some possible underlying causes of nonunions?
1. infection (contaminated wounds in open fracture are 5X more likely to develop complications)
2. fracture gaps
3. metabolically unhealthy
69
a ____ is a fracture that heals in a non-anatomic position
malunion
70
causes of a malunion include
1. ____ fracture
2. ____ treated fracture
3. premature ____ weight bearing on fracture
untreated ; improperly ; excessive
71
what are some clinical signs seen in malunion
angular limb deformities, limb shortening, gait abnormalities, degenerative joint disease
72
a fracture that has not healed in expected time considering the patient and the fracture environment is called a _____ union.
delayed
73
what provides the majority of blood supply to the bone marrow?
nutrient artery
74
what vessels are involved in blood supply to the bone?
nutrient artery, periosteal vessels, epiphyseal & metaphyseal vessels
75
TRUE OR FALSE differences in blood supply do not exist depending on growth versus maturity phase
FALSE - they do exist
76
what is blood supply is most important after injury to the bone?
extraosseous - which supplies early periosteal callus
77
true or false: medullary blood supply eventually takes back over after extraosseous steps in after an injury to the bone.
TRUE
78
what is a very important tool for fracture complications?
bone grafts
79
autogenous graft transplant occurs....
A. within the same individual
B. different individuals, same species
C. different individuals, different species
A
80
allograft occurs with...
A. within the same individual
B. different individuals, same species
C. different individuals, different species
B
81
xenograft occurs with...
A. within the same individual
B. different individuals, same species
C. different individuals, different species
C
82
what are the 4 "O's" of bone grafting?
osteogenesis, osteoconduction, osteoinduction, osteopromotion
83
osteoconduction is where the graft acts as a ______ in which new bone is laid down
scaffold
84
osteoinduction is where a graft induces cell to promote new ___. BMP works here.
bone ; BMP = bone morphogeneic protein
85
osteopromotion is where material enhances the ______ of new bone.
generation
86
platelet rich plasma is important in enhancing the regeneration of bone in _______.
osteopromotion
87
cancellous bone grafts from the trabecular bone work by....
the O's of bone grafting
88
few cells survive once the bone graft is separated from its blood supply, these cells are called ________.
osteogenic cells
89
what cells are induced to form bone cell lines in bone grafts?
mesenchymal stem cells, BMP's also play an important role here
90
depositing of new bone occurs via ____ cells.
osteoprogenitor
91
what are some indications for bone grafts?
1. any orthopedic fracture or arthrodesis
2. infected fractures
3. bone loss - cysts, fractures
4. limb sparing for bone tumors
92
what are the most common places to harvest a cancellous bone graft from?
wing of ileum, proximal tibia, humerus
