5-6: OCD + Normal Joint Review Slides

Question 1

Explain the mechanism/etiology of OC:

Answer 1

Improper/failure of endochondral ossification
Persisting chondrocytes in the zone of hypertrophy (failure of vascular invasion & ossification)
Cartilage thickening due to failure of EO

Question 2

What is the source of OC?

Answer 2

Chondrocyte/ECM/Vasculature
Exacerbated by trauma

Question 3

Stages of progression to OCD/SBC:

Answer 3

Osteochondrosis latens
Osteochondrosis manifesta
Osteochondrosis dessicans or Subchondral Bone Cyst

Question 4

Osteochondrosis latens:

Answer 4

focal cartilage necrosis
*can heal or progress

Question 5

Osteochondrosis manifesta

Answer 5

Bone does not occur in the area of focal necrosis (cartilage in place of bone)

Question 6

Osteochondrosis dessicans:

Answer 6

trauma causes shearing off of cartilage +/- bone

Question 7

What forces are typically associated with OCD:

Answer 7

gliding forces

Question 8

What is the pathophysiology of SBC:

Answer 8

Trauma causes cartilage lesion
Joint fluid in lesion-> inflammation-> bone resorption

Question 9

What forces are typically associated with SBC?

Answer 9

Weight bearing forces

Question 10

When can you see OCD on radiographs?

Answer 10

when a bone fragment is involved

Question 11

What are common lameness exam findings for OCD (2)?

Answer 11

Most will have joint effusion and will be positive to flexion

Question 12

Diagnostics for OCD:

Answer 12

U/S, contrast rats, CT, MRI, NS, PET scan
Rads if bone involvement

Question 13

Most common site of OCD in the femoropatellar joint:

Answer 13

Lateral trochlear ridge of the femur

Question 14

Common lesion for OCD in the femoropatellar joint:

Answer 14

Kissing lesion on patella

Question 15

Common findings with tibiotarsal OCD (2);

Answer 15

minimal lameness
obvious bog spavin- effusion presents early

Question 16

Common sites of OCD in the tibiotarsal joint:

Answer 16

DIRT
Medial Malleolus of Tibia
DL trochlear ridge of tarsal bone
Anywhere else

Question 17

Prognosis of metacarpo/metatarso-phalangeal OCD:

Answer 17

Generally good

Question 18

Subchondral bone cyst definition:

Answer 18

Invaginations of bone adjacent to articular surfaces filled with non mineralized matrix and lined with fibrous tissue

Question 19

Diagnostics for SBC-

Answer 19

ID on rads- lucency

Question 20

Common site for Femorotibial SBC:

Answer 20

Medial FT Joint- Medial femoral condyle

Question 21

Common site for metacarpo/metatarso-phalangeal SBC:

Answer 21

Typically medial condyle

Question 22

Prognosis of DIRT OCD with surgical tx:

Answer 22

Excellent

Question 23

Prognosis of OCD/SBC of lateral trochlear ridge of the femur with surgical tx:

Answer 23

fair to good

Question 24

Prognosis of Medial femoral condyle OCD with surgical tx:

Answer 24

fair

Question 25

Prognosis of shoulder OCD with surgical tx:

Answer 25

guarded

Question 26

Components of Hyaline Cartilage:

Answer 26

Primarily ECM
Avascular & Aneural

Question 27

Main action of subchondral bone:

Answer 27

Shock absorption