Lecture 13: Osteochondrosis and Subchondral Cystic Lesions Flashcards
what lesions can be considered Developmental Orthopedic Disease (DOD)
OCD, angular limb deformities, SCB cysts, physitis, flexural deformities, cuboidal bone deformity, vertebral malformation
What is Osteochondrosis
Failure of endochondral ossification in articular-epiphyseal complex (growth plate)
What is Osteochondritis dissecans (OCD)
Clinical condition of synovitis due to disrupted joint surface due to DOD
What are Subchondral bone cysts (SCB)
Invaginations into the bone just below the articular cartilage filled with debris and lined with fibrous tissue
What is juvenile osteochodnral conditions
Specific to disturbance of chondral ossification of the AE complex
Describe endochondral ossification
Starts as cartilage and as cartilage expands it ossifies from center to outward
Where are the locations for endochondral ossification
- Epiphysis, joint surface, metaphysical growth plate
- Secondary ossification center s- carpal and tarsal bones, apophyses
Failure of endochondral ossification results in __which in legs causes ___ and in neck causes ___
Osteochondrosis
Leg- lameness
Neck- neurological signs (wobblers)
What is the zone of hypertrophy
Chondrocytes are fatter and expanding as cartilage and then ossify behind
What is the blue arrow pointing at
zone of hypertrophy
Lesions of Osteochondrosis are a result of persisting ___
Chondrocytes in the zone of hypertrophy— cartilage becomes thicker but doesn’t ossify
What can cause chondrocytes to persist in zone of hypertrophy
- Failure of vascular invasion
- Failure of ossification
what does this show
Failure of Osteochondrosis, cartilage becomes thicker, not strong
What does this show
left: Osteochondrosis (not dissecans because hasn’t broken off yet)
Right: healing but still cartilage, bone has just formed around
What does this show
OCD on trochlear ridge
What does this show
Subchondral bone cyst
What happens in the formation of Subchondral bone cyst
Articular defect allows synovial fluid pressure into Subchondral bone causing bone resorption
Enlarges until pressure equilibrates
OCD vs SBC, which forms from weight bearing
SBC
OCD vs SBC: which occurs from shear forces on gliding surfaces
OCD
OCD vs SCB: which forms from compressive forces on loaded areas
SCB
What is wrong here
Subchondral post cyst
What are some possible factors of OC
- Growth rate
- Diet
- Heritability
- Trauma (normal trauma on defective cartilage and excessive trauma on healthy cartilage)
- Exercise
Excess ___in diet is strongly implicated in OC
Energy- excess phosphorous and calcium
Deficiency in what trace mineral is linked to OC
Copper
Excess of what mineral leads to OC
Zinc
What does a deficiency in cooper cause to result in OC
Failure of hydroxylysine cross link in collagen (loss -of “grass in adobe”)
Lysyl oxidase requires Copper
What is the heritable cause for OC
Propensity for rapid growth (not a particular gene)
What are some clinical signs of OC
- Joint effusion
- Lameness
- DJD
OC can be asymptomatic if fragment is stable, you may need to ___if for sale
Treat the radiographs
What is the synovial fluid analysis like for OC
Normal
__% bilateral for OC
50%
What is wrong here
OCD at distal intermediate ridge of tibia
What does the treatment of OCD depend on
- Joint involved- accessibility, expected success
- Age of horse- give time for <1
What is the surgical treatment for OCD
Arthroscopy- remove fragment and loose cartilage, debridement parent bone to healthy bone with firm margins so fibrocartilage can fill in
How do you medically manage OC
- Relieve synovitis, prevent DJD- give Adequan IM and hyaluronic Acid IA
- Steroids (avoid in foals)
What is wrong here
SBC on medial femoral condyle
What are some signs for SBC
- Joint inflammation
- Effusion (likely fetlock only)
- Lameness
What is the conservation approach to OC for young horses
- Confine
- Minimize synovitis with IA hyalartin, adequan, cosequin
- Balance diet
- Minimize weight gain
What is the medical therapy for SBC
- Triamcinolone injection of cyst/lining
What are some surgical treatments for SBC
- Enucleate the cavity- remove fibrous lining and sclerotic bony margin
- Transcondylar bone screw
- Debridement and grafting
What does this show
Transconylar bone screw treating SBC
What is chondrocytes grafting
Put chondrocytes into joint with fibrin glue
Coffin joint primarily gets OCD or SBC
SBC
What does the lameness exam look like for SBC
- No swelling or effusion
- Digital flexion positive
What is wrong
SBC in coffin bone/ p3
What is the only site in the coffin joint where you can operate for OCD arthroscopically
Extensor process
What wrong
OCD of extensor process
How does the lameness exam look for SBC in pastern joint
Positive flexion
IA block test- abaxial with ring
What is wrong here
SBC at pastern joint
What does lameness exam look like for fetlock with OCD
- Lameness variable because multiple joints
- Fetlock effusion
- IA block
What is the most common fetlock OCD site- name and number
Sagittal- #1
What is wrong here
Sagittal ridge OCD- fetlock
what wrong here
SBC in fetlock
What is wrong here
SBC in radial carpal bone
Where are SBC common in elbow joint
Medial proximal radial condyle
T or F: elbow joint SCB are arthroscopically accessible
False, subarticular approach
What is wrong here
SBC in elbow/ humerus
Where is OCD generally in elbow
Distal numeral condyle
Is shoulder joint/ numeral OCD common
Yes
How do you dx shoulder joint/ numeral OCD
- IA blocks
- Scintigraphy
- Quality rads may require Anesthesia
What is wrong here
Shoulder/humeral OCD
Which is more common OCD or SBC on tibiotarsal joint
OCD
What does lameness show in tibiotarsal joint OCD
- Effusion- obvious bog spavin
- Minimal lameness- may require flexion
What is wrong here and likely cause
Tibiotarsal joint effusion/ bog spavin- OCD
What are the tarsal sites of predilection of OCD
- Distal intermediate ridge of tibia
- Medial malleolus of tibia
- Distal lateral trochlear ridge of tibial tarsal bone
What wrong here
OCD of distal intermediate ridge of tibia
What is wrong here
Lateral trochlear ridge OCD
What wrong here
Medial malleolar OCD
SBC or OCD more common in femorotibial joints
SBC (very common)
Where is SBC usually located in femorotibial joints
Medial femorotibial joint
What is wrong here
Medial femoral joint SBC
OCD or SBC: more common in femoropatellar joints
OCD
What is wrong here and likely cause
Femoropatellar joint effusion- OCD
What is wrong here
lateral trochlear ridge OCD
What wrong here
lateral trochlear ridge OCD
What does a lameness exam look like for coxofemoral joint for SBC
Positive flexion
IA anesthesia
Where are coxofemoral joint SBC located
Femoral head
