OCD/Arthroscopy

Question 1

What is osteochrondrosis ?

Answer 1

Process of abnormal bone and cartilage formation

Question 2

What is osteochrondrosis dissicans?

Answer 2

Lesions that penetrate the joint surface, creating inflammation and effusion

Question 3

What process contributes to longitudinal bone growth?

Answer 3

Endochrondrial ossification

Question 4

How does endochondral ossification occur?

Answer 4

Chondrocytes form calcified columns in hypertrophic zone

Undergo programmed cell death

Primary spongiosa if formed by osteoblasts in the calcified columns

Question 5

What is the pathophysiology of OCD?

Answer 5

Failure of blood vessels to penetrate the calcified cartilage

• persistence of cartilage —> chondrocyte clones (small cell clusters)
• formation of cysts —> necrosis of deeper layer cartilage
• formation of fissures —> formation of flap

Occlusion of canals (vessels)

Epiphyseal necrosis

• mechanical sharing
• stress concentration
• blunt trauma
• repeated damage

Question 6

What is the pathophysiology of ocd at a young age?

Answer 6

Thickened cartilage 
Cyst like changes 
Degeneration of cartilage 
Uncalcified cartilage not vascularized 
Cracks in pathological cartilage

Question 7

What is the pathophysiology of OCD in an adult

Answer 7

Subchondral fibrosis

Fibrocartilage covers the defect (type 1 collagen, not as strong)

Sclerosis of subchondral bone (due to unstable joint, tries to strengthen by laying down new bone)

Osteophyte formation

=> degenerative osteoarthritis

Question 8

What are etiologies of OCD ?

Answer 8

Genetics

• heritable
• rapid growth potential
• familial tendencies
• animals with an inherent rapid growth potential
• 2:1 male:female

Nutrition

• low Ca: high P
• excess zinc or copper deficit
• vit A and D deficiency
• high protein diet
• high caloric intake

Trauma

Question 9

What are clinical signs of OCD?

Answer 9

Lameness (slight)
Decreased range of motion
Pain on manipulation

Synovial effusion (primary sign)

Bog spavin in the tarsal crural joint

Question 10

How can you diagnose OCD?

Answer 10

Radiology

Scintigraphy
-radioactive Ca incorporated into high turn over areas (lysis/sclerosis)

Arthroscopy

NMR

Question 11

Common sites of OCD in equine?

Answer 11

Tibiotarsal joint (hock) 
Stifle 
Fetlock 
Cervical vert 
Shoulder

Question 12

What the most common areas within the HOCK for OCD lesions?

Answer 12

Distal intermediate ridge of the tibia

Lateral trochlear ridge

Medial trochlear ridge

Medial malleolus
Lateral malleolus

Question 13

What areas within the STIFLE do you most commonly see OCD lesions?

Answer 13

Lateral trochlear ridge

Medial trochlear ridge

Medial femoral condyle (cyst)

Question 14

Most common location within the FETLOCK for OCD lesions?

Answer 14

Sagittal ridge of MC III

Caudal eminence of P1

P1 or MC III cyst

Question 15

Treatment for OCD?

Answer 15

Rest

Intra-articular meds

Surgery

• arthrotomy
• arthroscopy

Joint substances
Chondroprotective agents 
-glucosamine 
-chondrotin sulfate 
-hyaluronic acid 
-PSGAG
-anti inflammatory
-steroids (IA or systemic)

Question 16

What are some advanced surgical options that can be used to treat OCD?

Answer 16

Osteochondral dowel grafts (harvested from non-weight bearing areas)

Autologous chondrocyte transplantation (ACT)

Gene therapy

Question 17

What are the advantages to using arthroscopy?

Answer 17

Minimal joint trauma
Can evaluate joint
Remove debris/chips
Infection is reduced compared to arthrotomy

Question 18

When doing arthroscopy you need to distend the joint with ________ to allow for visualization

Answer 18

LRS

Question 19

What arthroscopy technique uses the arthroscope and an egress cannula coming into the joint at converging angles?

Answer 19

Triangulation technique

Question 20

What is the purpose of the egress cannula?

Answer 20

Allow fluid to drain out of the joint capsule so it doesn’t extravasated peri-articularly

Question 21

What are abnormal changes of the synovial capsule that you might observe with arthroscopy?

Answer 21

Hyperemia
Thickened villi
Petechiation

Question 22

What are abnormal changes that you may observe in the cartilage during arthroscopy?

Answer 22

Fibrillation

Erosions/wear lines

Full thickness cartilage loss

Question 23

Where are chip fractures most common in the carpus?

Answer 23

Distal radial carpal bone

Proximal intermediate carpal bone

Distal lateral radius