Osteochondrosis

Question 1

What are the different classifications of osteochondrosis based on disease stage?

Answer 1

1. Osteochondrosis latens: early microscopic disease.
2. Osteochondrosis manifesta: subclinical, macroscopic and radiographic signs.
3. Osteochondrosis dissecans (osteochondritis dissecans): cartilage flap

Question 2

Are male or female dogs more frequently affected by osteochondrosis?

Answer 2

Male dogs aside from OCD of the talus

Question 3

What are the most common sites of osteochondrosis in the dog?

Answer 3

1. Humeral head
2. Medial and lateral (most common) femoral condyles
3. Medial and lateral trochlear ridges of the talus
4. Medial aspect of the humeral condyle

Question 4

How much growth are the growth plate and epiphyseal ossification centres responsible for, respectively?

Answer 4

Growth plate: 75-80%
Epiphyseal ossification centre: 20-25%

Question 5

At what age are epiphyseal ossification centres typically closed with remaining growth occurring only through the growth plate?

Answer 5

Around 26 weeks of age

Question 6

What are the ages of complete fusion of the growth plates in dogs?

Answer 6

Question 7

What constrains circumferential expansion of the growth plate during growth?

Answer 7

Perichondral ring of Lacroix

Question 8

What are the zones of the growth plate?

Answer 8

Resting zone, proliferative zone, hypertrophic zone, zone of mineralization.

Question 9

What is the only zone of the growth plate that is vascularized?

Answer 9

The resting zone, via chondroepiphyseal vessels

Question 10

What are the two distinct layer of the articular epiphyseal complex in the developing bone?

Answer 10

Outer layer: avascular region that becomes articular cartilage. Does not participate in endochondral ossification.

Inner layer: similar to the growth plate in that it is responsible for epiphyseal enlargement, but it is relatively disorganized and has abundant vasculature from the chondroepiphyseal vasculature.

Question 11

What are the layers of mature articular cartilage?

Answer 11

Superficial zone, transitional zone, radial zone, tidemark, zone of calcified cartilage

Question 12

Does conversion of cartilage into bone occur at the periphery or toward the centre of the epiphyseal-articular complex?

Answer 12

Toward the center

Question 13

What are some proposed risk factors for development of OCD?

Answer 13

Hereditary (including anatomic/conformation), trauma, dietary, rapid growth.

Question 14

What are the two types of osteochondrosis lesions as proposed by Olsson and Reiland?

Answer 14

Type 1: Lesion occurs at the center of the affected articular surface, away from vascular attachments (i.e. OCD of the humeral head, femoral condyles, humeral trochlea).

Type 2: Lesion occurs at the joint margin and retains a vascular attachment (i.e. trochlear ridges of the talus, fragmented MCP)

Question 15

What is the proposed etiology of articular OCD lesions?

Answer 15

Question 16

What is the proposed etiology of growth plate OCD lesions?

Answer 16

Question 17

What is a potential example of a growth plate manifestation of OCD?

Answer 17

Retained cartilaginous core (typically distal ulna)

Question 18

Should cartilage surrounding an OCD lesion be bevelled or squared off at the time of surgery?

Answer 18

Squared off (bevelled edges have been reported to impeded fibrocartilage formation)

Question 19

What are some palliative repair techniques described for the treatment of OCD?

Answer 19

Debridement and lavage

Question 20

What are some reparative repair techniques described for the treatment of OCD?

Answer 20

Curettage, spongialization, abrasion athroplasty, forage, microfracture

Question 21

What are some restorative repair techniques described for the treatment of OCD?

Answer 21

Fragment reattachment, osteochondral transplants, synthetic osteochondral resurfacing

Question 22

What is the most common donor site for dogs undergoing OATS for dogs?

Answer 22

Medial sulcus terminalis or medial and lateral trochlear ridges of the femur

Question 23

What implant is depicted in the image from Murphy 2019 in Vet Surg?

Answer 23

Synthetic osteochondral resurfacing implant (A: first generation, B: second generation).