Osteochondral fragmentation

Question 1

OCD pathogenesis

Answer 1

• cartilage at end of epiphysis is thickened and necrotic through osteochondrosis
• fissures appear in weak cartilage
• mineralisation occurs within the lesion
• sometimes break free -> fragmentation
• lesions form during periods of fast growth
  – all lesions originate <2y/o
• dynamic process in <8mo -> lesions may heal

Question 2

OCD - common breeds

Answer 2

• large TBs and WBs

Question 3

OCD - predilection sites

Answer 3

• locations where bones slide over each other
• stifle (lateral trochlear ridge of the femur)
• hock (distal intermediate ridge of the tibia)
• other locations less common, e.g. shoulder, fetlock, other locations in the hock

Question 4

OCD - when can CS appear?

Answer 4

• straight away (as a 1y/o)
• when horse begins work (2/3/4y/o depending on discipline)
• never (lesion remains sub-clinical)

Question 5

OCD - CS

Answer 5

• mild to moderate lameness, worse after flexion
• joint effusions and heat

Question 6

OCD - diagnosis

Answer 6

• radiography

Question 7

OCF pathogenesis

Answer 7

Small piece of periarticular bone fractures off in a traumatic manner

As part of OA
- periarticular osteophytes form then fracture off
- subchondral bone disease creates weakening -> bone breaks away

Following bone trauma
- 1 bone bumps into another due to overextension at high speed

As an avulsion associated with a ligament insertion
- strain to ligament pulls off a bone fragment

Question 8

OCF - typical presentation

Answer 8

• can occur at any age
• common in athletic horses (racehorses/eventers)

Question 9

OCF - predilection sites

Answer 9

• carpus
• fetlock
• coffin joint
• others

Question 10

OCF - when can CS appear?

Answer 10

• straight away
• later when the fragment contributes to further OA development
• never (lesion remains sub-clinical)

Question 11

OCF - CS

Answer 11

• mild to moderate lameness, worse after flexion
• joint effusion and heat

Question 12

OCF - diagnosis

Answer 12

• radiography usually

Question 13

Treatment options for OCD & OCF

Answer 13

Conservative
- do nothing
- if no CS and not for sale

Medical
- IA meds, NSAIDs
- temporary improvement
- likely to lead to OA in future due to ongoing synovitis

Surgical
- arthroscopic fragment removal

Euthanasia
- rarely required

Question 14

Arthroscopic fragment removal - use & what is done

Answer 14

• gold standard
• fragments removed
• necrotic underlying bone debrided
• fibrillated cartilage trimmed

Question 15

Arthroscopic fragment removal - prognosis

Answer 15

Excellent
- defect covers with fibrocartilage
- physio ipportant
- short recovery
- often return to full soundness