Developmental disease (Yr 3)

Question 1

what is the precursor to bone in utero?

Answer 1

cartilage

Question 2

where are the two sites of endochrondral ossification?

Answer 2

metaphyseal growth plate
articular-epiphyseal cartilage complex

Question 3

what are the main areas of longitudinal bone growth?

Answer 3

metaphyseal (growth plates)
epiphyseal (articular epiphyseal cartilage complex)

Question 4

how do cuboidal bones grow?

Answer 4

epiphyseal articular cartilage complex (don’t have a secondary centre of ossification/growth plate)

Question 5

what anatomical sections are there at the growth plate?

Answer 5

resting cartilage
proliferative cartilage (when they divide)
hypertrophic cartilage (cells get bigger)
calcifying cartilage (cells die and get calcified)
secondary spongiosa

Question 6

is blood supply needed for endochondral ossification?

Answer 6

yes

Question 7

when may endochondral ossification malfunction at the physical growth plate?

Answer 7

abnormal deposition of the matrix
abnormal mineralisation
poor conversion to bone
retention of cartilage

Question 8

what are the results of malfunction in the process of endochondral ossification at the physical growth plates?

Answer 8

slow or uneven growth

Question 9

what are the results of malfunction in the process of endochondral ossification at the articular-epiphyseal cartilage complex?

Answer 9

slow or uneven growth
cartilage flaps

Question 10

what are the affects of abnormal endochondral ossification?

Answer 10

affects the…
rate of growth
direction of growth
health of articular cartilage

Question 11

what is chondrodysplasia?

Answer 11

abnormal endochondral ossification leading to stunted growth

Question 12

what is osteochondrosis?

Answer 12

broad term describing abnormalities associated with the cartilages found in joints

Question 13

what is osteochondritis?

Answer 13

inflammation associated with osteochondrosis

Question 14

what is osteochondritis dissecans?

Answer 14

clinical manifestation of abnormal endochondral ossification leads to cartilaginous or osteochondral flaps/defects within the joint

Question 15

what are some abnormalities that can lead to OCD?

Answer 15

disruption of blood supply
abnormal chondrocyte maturation
defective matric production
persistence of hypertrophic chondrocytes

Question 16

what do the abnormalities in development during OCD lead to?

Answer 16

thickened retained hypertrophic cartilage
disruption of the subchondral bone plate

Question 17

how does disrupted blood supply lead to OCD?

Answer 17

affects the mineralisation of subchondral bone which then alters the biochemical/biomechanical properties of cartilage and subchondral bone that then affects its ability to adapt and withstand forces

Question 18

what are the sequelae to the cartilage and subchondral bone of OCD cases to not be able to withstand forces?

Answer 18

inability to withstand forces/weight bearing
separation at osteochondral junction
cartilage flaps/fragments form
subchondral bone becomes exposed leading to inflammation

Question 19

what are the clinical signs of OCD?

Answer 19

effusions
fragments on radiographs
arthritis and lameness

Question 20

what can predispose animals to OCD?

Answer 20

rapid growth
genetic predisposition
nutrition (excess energy/protein, calcium/phosphorous imbalances)
trauma

Question 21

when is surgical management of OCD carried out in horses?

Answer 21

only after 12 months of age, some can resolve themselves as the horse grows

Question 22

what can untreated osteochondrosis dissecans lead to?

Answer 22

osteoarthritis

Question 23

what is the difference between osteochrondrosis dissecans and osteochondritis dissecans?

Answer 23

no clinically relevant difference (treat them as the same thing)

Question 24

what radiographic abnormalities can be seen with OCD?

Answer 24

irregular subchondral bone
osseous densities (mineralised cartilage, osteochondral fragments)

Question 25

what are the developmental orthopaedic diseases of horses?

Answer 25

osteochondrosis (OCD, subchondral bone cysts) physitis angular limb deformities flexural deformities

Question 26

what are the developmental orthopaedic diseases of dogs?

Answer 26

osteochondrosis (uninvited anconeal process, fragmented medial coronoid process) hypertrophic osteodystrophy legg calve perthes hip dysplasia

Question 27

what are the developmental orthopaedic diseases of cows?

Answer 27

oestochondrosis flexural deformities

Question 28

what is the aetiology of subchondral cyst-like lesions?

Answer 28

abnormal endochondral ossification leading to retention of a cartilage core and collapse of the cartilage under pressure from synovial fluid

Question 29

what is physitis?

Answer 29

enlargement of the physis caused by inflammation and disrupted endochondral ossification

Question 30

what are the clinical signs of physitis?

Answer 30

lameness and stiff gait

Question 31

how is physitis treated?

Answer 31

self-limiting (just supportive therapy)

Question 32

what plane is an angular limb deformity in?

Answer 32

frontal

Question 33

what is valgus and varus?

Answer 33

valgus - lateral deviation varus - medial deviation

Question 34

what are the sites angular limb deformities are most commonly seen at?

Answer 34

metaphyseal growth plate epiphysis cuboidal bones (carpus, tarsus) metaphysis