Subchondral lucencies Flashcards
(17 cards)
What are the 2 subchondral lucency diseases?
- subchondral cystic lesions (SCL)
- lytic/flattened areas in the subchondral bone plate (-> osteochondrosis lesions that have not progressed to OCD or SCL)
SCL pathogenesis - 2 ways it can develop
- progression of osteochondrosis lesion
- trauma to articular cartilage and/or subchondral bone
SCL pathogenesis - progression of osteochondrosis lesion
- blood supply failure within thickened epiphyseal cartilage
- ischaemic chondronecrosis
- tissue collapse
- development of a cyst with inflammatory lining
- self propagation
- large TB & WB <2y/o
- reasonably common
SCL pathogenesis - trauma to articular cartilage and/or subchondral bone
- occurs as part of OA
- cysts form when synovial fluid pressed into cartilage defect causing bone lysis
- usually pre-existing OA or recent joint trauma e.g. incomplete fracture
- any age
- uncommon
SCL predilection sites
- locations where bones crush into each other under weight bearing
- stifle (medial femoral condyle)
- phalanges
- other locations less common e.g. elbow, carpus
SCL - when can CS appear?
- straight away (as a 1y/o)
- when horse begins work (2/3/4y/o depending on discipline)
- never (lesion remains sub-clinical)
SCL - CS
- significant lameness, worse after flexion
- joint effusions & heat
Stifle SCL grading
Grade 1
- flattening or small defect in the subchondral bone of the central medial femoral condyle
Grade 2
- <10mm dome-shaped lucency
Grade 3
- a condylar lucency with no evidence of a cloaca in the subchondral bone
Grade 4
- ≥10mm large dome shape extending to the articular defect
Grade 5
- ≥10mm lucency with a narrow cloaca at the articular surface
Grade 6
- grade 4 or 5 SCl and other licences in the caudal medial femoral condyle or proximal medial tibial plateau
SCL tx options
- 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
SCL tx: intra-lesional injection with corticosteroids - use
- for SCL which communicate with the joint
- 67% success rate under GA for medial femoral condyle
- under arthroscopic guidance
- counteract self-propagation
SCL tx: mesenchymal stem cells within the joint - use
- reported recently in young TB racehorse population
- 84% return to racing
- no need for arthroscopy
- but done under GA with US guidance
SCL tx: arthroscopic debridement - use
- purpose is to remove unsupported cartilage
- decried cystic cavity
- has been associated with meniscal lesions
- some lesions enlarge after surgery (synovial fluid would get in there and the pressure would cause them to enlarge)
- ? suitable for grade 1 or 2 lesions
- rarely done now
SCL tx: transcondylar lag screw (standard cortical screw) - use
- under GA
- compressive forces stimulate new bone formation within cyst
- most popular tx atm
- do normally see the cysts fill to some extend but don’t disappear
SCL tx: transcondylar bone screw (absorbable screw) - use
- under GA
- doesn’t need removing
- may be more useful in the future
SCL tx - success rate with screw across the SCL
- earlier reports: 75%
- now up to 88% (radius)
- absorbable screw: 71% returned to racing
SCL tx: conservative management - use
- acceptable if SCL doesn’t cause lameness
- but needs monitoring in time
Lytic/flattened areas in subchondral bone plate - tx
- debride or leave alone depending on if causing CS
