Pathobiology of Developmental Disorders

Question 1

what is osteochondrosis?

Answer 1

disturbance of endochondral ossification that leads to cartilage retention

Question 2

what is osteochondritis dissecans?

Answer 2

manifestation of osteochondrosis in which a flap of cartilage is lifted from the cartilage surface

Question 3

what does failure of endochondral ossification lead to?

Answer 3

cartilage thickening which may result in malnourished, necrotic chondrocytes

Question 4

osteochondrosis does not apparently cause clinical signs until a loose flap forms, termed ____________________________

Answer 4

osteochondritis dissecans

Question 5

what is the signalment of osteochondritis dissecans of the proximal humerus?

Answer 5

large and giant breed dogs
rare in small dogs or cats
males more than females
clinical signs between 4-8 months

Question 6

what can be found on the physical exam of osteochondritis dissecans?

Answer 6

crepitus or joint swelling seldom evident
extreme extension of the shoulder elicits pain
extreme flexion of shoulder might elicit pain
muscle atrophy may be present

Question 7

what is diagnosis of osteochondritis dissecans of the proximal humerus based on?

Answer 7

typical radiographic findings in lateral view

Question 8

what is the treatment of osteochondritis dissecans?

Answer 8

remove flap
curette to subchondral bleeding bone
rest for 4-6 weeks
defect fills with fibrocartilage

Question 9

where is canine stifle osteochondritis dissecans usually?

Answer 9

medial aspect of lateral femoral condyle

Question 10

where is canine hock osteochondritis dissecans usually?

Answer 10

medial trochlear ridge of talus

Question 11

where is canine elbow osteochondritis dissecans usually?

Answer 11

medial humeral condyle

Question 12

what are the most common lesions in the equine stifle with osteochondrosis?

Answer 12

osteochondritis dissecans of the lateral trochlear ridge of the femur
subchondral bone cyst of medial femoral condyle

Question 13

when do horses present with osteochondrosis in the stifle?

Answer 13

any age
usually younger horses

Question 14

what are the clinical signs of osteochondrosis in the equine stifle?

Answer 14

joint effusion
lameness

Question 15

how are lateral trochlear ridge lesions in horses treated?

Answer 15

arthroscopic debridement
conservative not as good

Question 16

how does the prognosis of subchondral bone cysts in horses compare to that of lateral trochlear ridge lesions?

Answer 16

worse than lateral trochlear ridge lesions

Question 17

what is the most common location of osteochondrosis in the equine hock?

Answer 17

cranial, distal intermediate ridge of the tibia

Question 18

how is osteochondrosis in the equine hock treated?

Answer 18

arthroscopic debridement

Question 19

of the equine joint osteochondroses, which one has the least favorable prognosis?

Answer 19

equine shoulder osteochondritis dissecans

Question 20

what is arthroscopic debridement for equine shoulder osteochondritis dissecans best for?

Answer 20

mild to moderate lesions

Question 21

what is canine elbow dysplasia?

Answer 21

a collection of developmental diseases of the canine elbow

Question 22

what are the three main manifestations of canine elbow dysplasia?

Answer 22

fragmented medial coronoid process of ulna
ununited anconeal process of ulna
osteochondritis dissecans of medial humeral condyle

Question 23

what is a fragmented medial coronoid process?

Answer 23

separation of medial coronoid process from the ulna

Question 24

when does the anconeal process usually fuse?

Answer 24

13 weeks

Question 25

what does the prognosis of an ununited anconeal process vary with?

Answer 25

degree of osteoarthritis

Question 26

what induces joint inflammation in osteochondritis dissecans?

Answer 26

cartilage degradation products reaching synovial fluid

Question 27

what can be seen on radiographs with osteochondritis dissecans?

Answer 27

earliest: flattening of subchondral bone of the caudal humeral head
saucer-shaped radiolucent area
calcification may allow visualization in situ or within joint

Question 28

what type of cartilage heals an osteochondritis bed?

Answer 28

fibrocartilage replaces hyaline cartilage

Question 29

what is the prognosis of canine stifle osteochondritis dissecans?

Answer 29

guarded

Question 30

what age is usually affected by canine stifle osteochondritis dissecans?

Answer 30

6-9 months old

Question 31

which type of osteochondritis dissecans is least common in dogs?

Answer 31

canine stifle osteochondritis dissecans

Question 32

is a subchondral bone cyst of the medial femoral condyle or an OCD lesion of the lateral trochlear ridge of the femur a better prognosis?

Answer 32

lateral trochlear ridge lesions better prognosis

Question 33

how often is osteochondrosis of the equine hock bilateral?

Answer 33

45-50%

Question 34

how is prognosis of osteochondrosis of the equine hock?

Answer 34

good to excellent

Question 35

what are some potential causes of canine elbow dysplasia?

Answer 35

decreased radius of curvature of the ulnar trochlear notch
asynchronous growth between radius and ulna

Question 36

how does separation of the femoral medial coronoid process and the ulna occur?

Answer 36

calcified trabeculae then covered with fibrous connective tissue
fragmentation of coronoid

Question 37

what are some indications for surgery with fragmented medial coronoid process?

Answer 37

persistent lameness
mild DJD

Question 38

what has been implicated in osteochondrosis?

Answer 38

genetics
rapid growth
over-nutrition
trauma
ischemia
hormonal factors

Question 39

does osteochondrosis cause clinical signs before a loose flap develops?

Answer 39

no

Question 40

why is arthroscopy to fix osteochondritis dissecans of the humeral head difficult?

Answer 40

overlying muscle mass