ch 73 Osteochondrosis Flashcards
(97 cards)
1
Q
osteochondrosis latens
A
early microscopic cartilaginous lesion
2
Q
osteochondrosis manifesta
A
subclinical lesion that is macroscopically and radiographically apparent
3
Q
osteochondrosis dissicants
A
disease if attached or loose cartilage flap is present
4
Q
when is there first evidence of skeletons on radiographs
A
19-25 days post fertilization
5
Q
growth plates contribute to ____ % of final bone length
A
75-80%
6
Q
eiphysis contributes approximately _____ % of final bone length
A
20-25%
7
Q
what is the incidence of osteochondrosis
A
8.1/1000pt
8
Q
sex predisposition for OCD
A
males except for talus OCD
9
Q
most common OCD locations in dogs
A
caudal humeral head
medial humeral condyle
lateral femoral condyle
medial or lateral trochlear ridge of the talus
10
Q
most common OCD locations in cats
A
Centro-caudal aspect of proximal humeral condyle,
lateral femoral condyle
11
Q
by what process do joints form between developing bones
A
segmentation and cavitation
12
Q
when does the majority of longitudinal growth take place?
A
12-26wks
13
Q
how do growth plates enlarger
A
via formation of new cartilage
14
Q
what determines volume of newly formed cartilage
A
chondrocyte proliferation
chondrocyte enlargement
matrix formation
15
Q
Humerus, diaphysis
age when ossification center appears
age when fusion occurs
A
birth
16
Q
Humerus (proximal epiphysis)
age when ossification center appears
age when fusion occurs
A
1-2 wk
10-13 mo
17
Q
Humerus (distal epiphysis)
age when ossification center appears
age when fusion occurs
A
1-2 wks
6-8 mo to shaft
18
Q
Humerus (medial condyle)
age when ossification center appears
age when fusion occurs
A
2-3 wks
6wks to lateral condyle
19
Q
Humerus (lateral condyle)
age when ossification center appears
age when fusion occurs
A
2-3 wks
20
Q
Humerus (medial epicondyle)
age when ossification center appears
age when fusion occurs
A
6-8 wks
6 months to condyle
21
Q
Radius (diaphysis)
age when ossification center appears
age when fusion occurs
A
birth
22
Q
Radius (proximal epiphysis)
age when ossification center appears
age when fusion occurs
A
3-5 weeks
6-11 months
23
Q
Radius (distal epiphysis )
age when ossification center appears
age when fusion occurs
A
2-4 weeks
8-12months
24
Q
Ulna (diaphysis)
age when ossification center appears
age when fusion occurs
A
birth
25
Ulna (olecranon)
age when ossification center appears
age when fusion occurs
8 wk
6-10 month
26
Ulna (distal epiphysis)
age when ossification center appears
age when fusion occurs
8 wks
8-12 months
27
Femur (diaphysis)
age when ossification center appears
birth
28
Femur (proximal epiphysis)
age when ossification center appears
age when fusion occurs
2 weeks
7-11months
29
Femur (trochanter major)
age when ossification center appears
age when fusion occurs
8 weeks
6-10months
30
Femur (trochanter minor)
age when ossification center appears
age when fusion occurs
8 wk
8-13months
31
Femur (distal epiphysis)
age when ossification center appears
age when fusion occurs
8-11 months (fusion)
32
Femur (trochlea)
age when ossification center appears
age when fusion occurs
2 weeks
3 mo condyle to trochlea
33
Femur (medial condyle)
age when ossification center appears
3 wk
34
Femur (lateral condyle)
age when ossification center appears
3 wk
35
Tibia (diaphysis)
age when ossification center appears
birth
36
Tibia (medial condyle)
age when ossification center appears
age when fusion occurs
3 wk
6 wk to lateral condyle
37
Tibia (lateral condyle)
age when ossification center appears
age when fusion occurs
3 wk
6-12 mo to shaft
38
Tibia (tuberosity)
age when ossification center appears
age when fusion occurs
8 wk
6-8 mon to condyle
6-12 mo to shaft
39
Tibia (distal epiphysis)
age when ossification center appears
age when fusion occurs
3 wk
8-11mo
40
Tibia (malleolus)
age when ossification center appears
age when fusion occurs
3 mo
5mo
41
fibula (diaphysis)
age when ossification center appears
birth
42
fibula (proximal epiphysis)
age when ossification center appears
age when fusion occurs
9 wk
8-12 month
43
fibula (distal epiphysis)
age when ossification center appears
age when fusion occurs
2-7 wk
5 month
44
Talus
age when ossification center appears
birth - 1 wk
45
fibular
age when ossification center appears
birth-1wk
46
define saltation
short period of active growth
47
Hueter-Volkmann law
Proposes the growth is impeded by increased mechanical compression and accelerated by reduced loading
48
what is expansion of the growth plate constrained by
ring of Lacroix
49
Does Chondrocytic proliferation and matrix synthesis occur primarily in the daytime or nighttime?
daytime
50
Does active mineralization primarily ocur in the daytime or nighttime?
nighttime
51
What is the appearance and characteristics of cells in the resting zone of the growth plate cartilage
Chondrocytes are small, randomly orientated and scattered irregularly through the matrix
Cells divide slowly
52
What is the appearance and characteristics of cells in the proliferative zone of the growth plate cartilage
chondrocytes are flat and relatively small
organized in columns
chondrocytes divide, slowly enlarge, and synthesize matrix
53
What is the appearance and characteristics of cells in the hypertrophic zone of the growth plate cartilage
chondrocytes are spheroid and relatively large
cells RAPIDLY enlarge
54
What are the appearance and characteristics of cells in the mineralization zone of the growth plate cartilage?
chondrocytes have obtained their final size/shape
newly formed matrix mineralizes
55
what stimulates clonal expansion of chondrocytes in the proliferation zone
IGF-1
56
what are the requirements for change into hypertrophic chondrocyte phenotype
Bone morphogenetic protein (BMP), Wnt/𝛽 catenin, Runx2, Runx 3, thyroid hormone, and other regulators
57
during the process of endochondral ossification, who produces VEGF and what does VEGF control
produced by hypertrophic chondrocytes
controls vascular ingrowth
58
what is enlargement of the epiphysis a function of
Chondrocyte proliferation
Chondrocyte enlargement
Matrix formation
Duration of chondrogenic activity in the chondro-epiphysis
59
where do vessels of the chondro-epiphysis juncture originate from
perichondral plexus
vessels course within cartilage canals
60
what is the heritability of OCD
10-45%
61
Over-feeding is thought to cause stimulation of chondrocyte differentiation and proliferation via elevated hormones including.......
Elevated levels of growth hormone
IGF-1 triiodothyronine (T3)
Thyroxine (T4)
Insulin
62
what are the zones of mature articular cartilage
superficial zone
transitional zone
radial zone
zone of calcified cartilage
63
what are the differences between the inner layer and the growth plate
Inner layer is visually disorganized and does not have the ordered zonal and columnar arrangemen of the growth plate
Chondroepiphysis has an abundant vasculature
64
when does the majority of longitudinal growth take place?
12-26 wks
65
how to growth plates enlarge
via formation of new cartilage
66
how does the increase in cartilage volume result in bone length growth
pushing articular-epiphyseal complex away from the metaphysis
67
where is the newly formed cartilage converted into bone
Junction of growth plate and metaphysis via endochondral ossification
68
who produces IGF-1
daughter cells in the resting zone
69
what role do osteoclasts play in endochondral ossification
remove transverse matrix septa that separates apoptotoic hypertrophic chondrocytes from metaphyseal vasculature, leaving voids lacunae for new vessels to form
70
What is the role of osteoprogenitor cells?
Differentiate into osteoblasts→lay down woven bone on calcified cartilage matrix, forming lattice of calcified cartilage and woven bone (=primary spongiosa)
71
What is secondary spongiosa?
Lamellar bone that replaces the calcified cartilage (primary spongiosa) and woven bone
72
What are the layers of the articular-epiphyseal complex?
Thin outer layer, thicker inner layer
73
Characterize the outer layer
Contains avascular specialized immature articular cartilage that will mature into articular cartilage; has no role in endochondral ossification
74
Characterize the inner layer
Functionally similar to the growth plate, responsible for epiphyseal enlargement and mineralization of new cartilage
75
What are the zones of the outer layer of the articular-epiphyseal complex (secondary ossification center)?
Superficial zone, transitional zone, radial zone, and zone of calcified cartilage
76
What is the radial zone?
Uncalcified cartilage
77
What separates radial zone from the zone of calcified cartilage?
The tidemark
78
What does the tidemark represent?
Completion of maturation process of the ossification zone
79
Where does chondrocyte proliferation take place within epiphysis?
on the periphery
80
Where does maturation take place?
Toward the center
81
What is chondrification?
Redundant cartilage canals regress as the ossification front moves from center of epiphysis to newly formed epiphyseal cartilage
82
What risk factors play a role in osteochondrosis?
Heredity, rapid growth, dietary factors, trauma
83
How might microtrauma cause ununited anconeal processes?
Overgrowth of radius may cause shear forces in growth plate of anconeal process
84
What is the primary lesion of osteochondrosis?
Unknown - proposed Focal necrosis of epiphyseal cartilage canals→cartilage ischemia and necrosis vs dyschondroplasia vs relative osteopenia
85
At what point does the proposed causes of OCD (primary) occur?
At a point in development when the vessels originating from the perichondrium are being replaced by vessels from adjacent epiphyseal bone marrow
86
How might the necrotic focus heal?
Through stages of granulation tissue and intramembranous ossification or deforms and becomes altered joint congruency, subchondral bone cyst, or fissure/cleft
87
How are OCD lesions graded?
I cartilage surface normal, cartilage slightly thickened, minuscule subchondral defect
II cartilage surface mottled; cartilage more thickened
III discoid elevation of cartilage surface, large cleft, sclerotic subchondral bone
IV typical partially detached cartilage flap or separated flap and joint mice
88
What are type I flaps vs type II flaps involving articular epiphyseal region?
Type 1 – occur at center of affected surface, away from vascular attachments (caudal humeral head, medial humeral condyle, medial or lateral femoral condyle)
Type 2- occur at joint margin, retain vascular attachments (talar ridges, coronoid process)
89
How do type II flaps heal?
Endochondral ossification
90
What is failure of endochondral ossification (osteochondrosis) characterized by if affecting the growth plate rather than articular surface?
Persistence of hypertrophic chondrocytes
91
What is a retained cartilaginous core?
Local thickening of a growth plate
92
What is found in the retained cartilage core?
Focal thickening of the growth plate , characterized by persistent, viable hypertrophic chondrocytes
93
What are the proposed mechanism of retained cartilaginous cores occurring?
Damage to resting zone cartilage canals or metaphyseal blood supply
94
What does damage to resting zone cartilage canals or metaphyseal blood supply cause?
Inhibits conversion of mineralized growth plate cartilage into metaphyseal bone , resulting in thickening of the hypertrophic zone of the growth plate
95
When are retained cartilaginous cores of clinical consequence?
When they are associated w/reduced length of the ulna with secondary deformities (bowing)
96
What is consequence of ulnar cartilaginous core (growth plate OC)?
Radial procurvatum, carpal valgus, elbow incongruity, short ulna
97
How do articular flaps heal following detachment?
Fibrocartilage
