Juvenile joint disease: osteochondral and subchondral pathology Flashcards
How do juvenile osteochondral conditions present?
- Varying degree of
- joint effusion
- lameness
- heat
- Positive to joint flexion
- Inflammation due to synovitis & osteitis
- cartilage has no nerves
- Often no clinical signs
- lesions detected on pre-sales radiographs
How are juvenile osteochondral conditions diagnosed?
- History
- Palpation
- Lameness assessment
- Regional anaesthesia (IA)
- Radiographs
- Ultrasound
MRI
CT
Nuclear scintigraphy
How should you interpret a radiographic lesion? What are Roentgen signs?
Radiographic description
* Number – 1/4/multiple
* Size – large/3cm/thin
* Shape – round / triangular/ irregular/ coallescing
* Opacity – radiolucent/ radiodense/ heterogenous
* Location – on distal lateral……
Make an assessment of pathology
- Lysis / sclerosis / new bone formation
Diagnosis
How would you describe this lesion?
One, large, oval, radiodense lesion on the distal intermediate ridge of the tibia.
What challenges are associated to juvenile joint disease diagnosis?
- Experience of owners/carers
- Owners expectations/purpose of the horse
- Lesions often silent until significant increase in exercise regime
- Horses from different disciplines will start at a different age
- Temperament may not be amenable to all diagnostic steps
- Some lesions may be cartilaginous only so not visible on radiographs
- It is possible for lesions to heal
What disease process is associated to osteochondrosis? What can it progress into? How is the process different to that of osteochondral fragmentation?
- developmental disease
- due to failure of endochondral ossification
- may progress into2 conditions:
- Osteochondritis Dissecans (OCD)
- Subchondral Cystic Lesions (SCL)
Osteochondral fragmentation (OCF)
- traumatic disease
What are treatment options for juvenile joint disease? What are gold standard for loose fragments in joint and thickened cartilage?
- Conservative
- no treatment
- Medical
- intra-articular medication
- Surgical
- arthroscopic fragment removal
- debridement of disease cartilage & necrotic subchondral bone
- other procedures
- Euthanasia
- Choice depends on disease severity and intended use
Loose fragments in joint (OCD & OCF)
- arthroscopic removal
Thickened cartilage (OC)
- Can monitor and see
What age and breeds are more likely to develop ostechondrosis and osteochondral fragmentation? When do clinical signs occur?
Osteochondrosis
Age - <2yo
Breed - thoroughbreds, warmbloods
Clinical signs - immediately, when horse begins work or never
Osteochondral fragmentation
Age - any age
Breed - any athlete
Clinical signs - immediately or never
Describe pathogenesis of osteochondrosis
- Focal failure of endochondral ossification at epiphyseal growth cartilage
- Follows trauma to microvasculature
- Strong location predispositions
- Lesions form during periods of fast growth
- all lesions originate <2yo
- Dynamic process in <8mo – lesions may heal
- Multifactorial
- Polygenetic heritable disease
- Overnutrition
- Rapid growth
- Mineral imbalances
How does osetochondrosis progress to further pathology?
Defect in endochondral ossification
- splitting of cartilage to give osteochondritis dissecans lesions
* Fissures appear in thickened cartilage
* Mineralisation occurs within the lesion
* Sometimes break free - fragmentation
- retention of cartilage and its necrosis leads to subchondral cystic lesion
* Blood supply failure within thickened epiphyseal cartilage
- Necrosis of thickened cartilage
* Cyst has an inflammatory lining, so is self-propagating - lysis
When does osteochondritis dessicans occur?
- Lesions form during periods of fast growth
- all lesions originate <2yo
- Dynamic process in <8mo – lesions may heal
What is the typical presentation of osteochondritis dessicans?
- Common in large Thoroughbreds and Warmbloods
- Strong predilection sites - locations where bones slide over each other:
- Stifle (lateral trochlear ridge femur)
- Hock (distal intermediate ridge of tibia)
- Other locations less common: e.g. shoulder / fetlock / other locations in the hock
- Clinical signs may appear:
- straight away (as a 1yo)
- when horse begins work (2/3/4yo depending on discipline)
- never (lesion remains sub-clinical)
- Mild to moderate lameness – worse after flexion
- Joint effusions & heat
- Diagnosis usually by radiography
How would you describe this lesion?
Multiple, small, round, radiodense lesions cranial to the lateral trochlear ridge of the femur
How would you describe this lesion?
One, large, oval, radiodense lesion proximal to the palmar/plantar medial/lateral aspect of the proximal phalanx
What are treatment options for OCD?
- Conservative
- do nothing
- if no clinical signs and not for sale
- Medical
- IA medications, NSAIDs
- Temporary improvement (the sticking plaster approach)
- Likely to lead to OA in future due to ongoing synovitis
- Surgical
- arthroscopic fragment removal
- Euthanasia
- rarely required
What is gold standard treatment of OCD?
Arthroscopic fragment removal
- Fragments removed
- Necrotic underlying bone debrided
- Fibrillated cartilage trimmed
Excellent prognosis
* defect covers with fibrocartilage
* physiotherapy important
* short recovery
* often return to full soundness
What are the 2 types of subchondral cystic lesions?
- Progression of osteochondrosis lesion
- Trauma to articular cartilage and/or subchondral bone
How do traumatic subchondral cystic lesions occur?
- Occurs as part of OA
- Cyst forms when synovial fluid pressed into cartilage defect causing bone lysis (Hydraulic theory)
- Usually pre-existing OA or recent joint trauma e.g. incomplete fracture
- Any age
- Not common
What is the typical presentation of subchondral cystic lesions?
- Strong 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
- Clinical signs may appear:
- straight away (as a 1yo)
- when horse begins work (2/3/4yo depending on discipline)
- never (lesion remains sub-clinical)
- Significant lameness – worse after flexion
- Joint effusions & heat
- Diagnosis usually by radiography
How would you describe this lesion?
One, large, oval, radiolucent lesion in the medial femoral condyle
How would you describe this leison?
One, large, round, radiolucent lesion within the proximal aspect of the middle phalanx, (also considerable periarticular new bone formation and joint collapse).
What are the SCL grades?
1 - flattening or small defect on subchonral bone
2 - indentation
3 - round cyst
4 - oval with open neck
5 - small neck and large cyst
6 - SCL with other SCL on adjacent bone
What are the treatment options for SCL?
Intra-lesional injection with corticosteroids
* For SCL which communicate with the joint
* 67% success rate under general anaesthesia for medial femoral condyle
* Under arthroscopic guidance
* Counteract self-propagation
Mesenchymal stem cells within the joint
* Reported recently in young thoroughbred racehorse population
* 84% return to racing (Klein et al, 2022)
* No need for arthroscopy
* But done under general anaesthesia
* With ultrasound guidance
Arthroscopic debridement
* Purpose is to remove the unsupported cartilage
* Debride cystic cavity
* Has been associated with meniscal lesions
* Some lesions enlarge after surgery
* ? suitable for grade 1 & 2 lesions
Transcondylar lag screw- standard cortical screw
* Under general anaesthesia
* Compressive forces stimulate new bone formation within cyst
Transcondylar bone screw- absorbable screw
- Under general anaesthesia
Describe pathogenesis of osteochondral fragmentation (OCF)
Small piece on periarticular bone fractures off in a traumatic manner
As part of osteoarthritis
* periarticular osteophytes form then fracture off
* subchondral bone disease creates weakening - bone breaks away
Following direct trauma
* 1 bone bumps into another due to over extension at high speed
As an avulsion associated with a ligament insertion
* strain to ligament pulls off a bone fragment
What is the typical presentation of OCF?
- Can occur at any age
- Common in athletic horses (racehorses / eventers)
- Strong predilection sites:
- carpus, fetlock, coffin joint and others
- Clinical signs may appear:
- straight away
- later when the fragment contributes for further OA development
- never (lesion remains sub-clinical)
- Mild to moderate lameness – worse after flexion
- Joint effusions & heat
- Diagnosis usually by radiography
Describe this lesion.
One, medium size, rectangular, radiodense lesion on the dorso-distal aspect of the radiocarpal bone
Describe this lesion.
One, small, round, radiodense lesion dorsal to the proximal aspect of the proximal phalanx.
What are the treatment options for OCF?
- Conservative
- do nothing
- if no clinical signs and not for sale
- Medical
- IA medications, NSAIDs
- Temporary improvement (the sticking plaster approach)
- Likely to lead to OA in future due to ongoing synovitis
- Surgical
- arthroscopic fragment removal
- Euthanasia
- rarely required
