Equine subchondal lucencies

Question 1

Describe the pathogenesis of subchondral cyctic lesions (SCL) through OCD

Answer 1

Blood supply failure within thickened epiphyseal cartilage
Ischemic chondronecrosis
Tissue collapse
Development of a cyst with inflammatory lining
Self propagation.

Question 2

What are the 2 possible ways SCL can form

Answer 2

1. Progression of osteochondrosis lesion
2. Trauma to articular cartilage and/or subchondral bone

Question 3

How do SCL from due to trauma

Answer 3

Occurs as part of OA
Cyst forms when synovial fluid pressed into cartilage defect causing bone lysis

Question 4

what are the predilection sites of SCL

Answer 4

Stifle (medial femoral condyle)- of tibia
Phalanges

Question 5

what signs can we see with SCL

Answer 5

Significant lameness (because in weight bearing areas) – worse after flexion
Joint effusions & heat

Question 6

List the treatment options for SCL

Answer 6

Intra-lesional injection with corticosteroids
Mesenchymal stem cells within the joint
Arthroscopic debridement
Transcondylar lag screw- standard cortical screw
Transcondylar bone screw- absorbable screw
conservative management

Question 7

Describe Intra-lesional injection with corticosteroids treatment of SCL

Answer 7

SCL has to communicate with joint
67% success rate

Question 8

Describe Mesenchymal stem cells within the joint treatment of SCL

Answer 8

in young horses
done under GA with ultrasound guidance

Question 9

Describe Arthroscopic debridement treatment of SCL

Answer 9

Purpose is to remove the unsupported cartilage
Debride cystic cavity
Suitable for grade 1 and 2 lesions
Has been associated with meniscal lesions
Some lesions enlarge after surgery

Question 10

Describe Transcondylar lag screw- standard cortical screw treatment of SCL

Answer 10

Under general anaesthesia
Compressive forces stimulate new bone formation within cyst

Question 11

what is the success rate with treating SCL with screws

Answer 11

Earlier reports: 75%
Now up to 88% (radius)

Absorbable screw:71% returned to racing

Question 12

when can we use conservative management of SCL

Answer 12

if SCL does not cause lameness
but need monitoring in time

Question 13

Describe Lytic / flattened areas in subchondral bone plate

Answer 13

Osteochondrosis lesions that have not progressed to OCD or SCL

Question 14

Describe how we treat Lytic / flattened areas in subchondral bone plate

Answer 14

Debride / leave alone depending if causing clinical signs