Osteochondrosis and Subchondral Bone Cyst Flashcards
What developmental process goes wrong to cause osteochondrosis dissecans in horses?
Endochondral Ossification (Bone formation during fetal development)
Why is surgical removal of an OCD fragment an important consideration for horses?
If you do not remove the fragment it will continue to rub and cause issues like arthritis
Where is one of the most common location of OCD?
In a joint
Most common joint:
Distal intermedial ridge of the tibia
What are some Developmental Orthopedic Diseases (DOD)?
Osteochondrosis, Subchondral bone cyst, flexural deformities, physitis, cuboidal bone deformity, cervical compressive myelopathy
What causes Osteochondrosis?
-Failure of endochondral ossification
-Chondrocytes persist in the zone of hypertrophy (no vascular invasion so it does not finish)
-Defect in the chondrocyte, extracellular matrix, vasculature, exacerbated by trauma)
What are the stages of OC?
-Subchondral bone
-Osteochondrosis latens - focal cartilage necrosis
-Osteochondrosis manifesta - cartilage where bone should be, weak spot
-Osteochondrosis dissecans - trauma causing the cartilage to shear off
What is a subchondral bone cyst (SBC)?
Trauma on retained cartilage on weight bearing surface
-Causes cartilage lesion
-joint fluid defect increases pressure and causes inflammation and bone resorption
Can a subchondral bone cyst lead to OC?
Yes, if pressure or damage occurs to that area
What are factors that can cause pathogenesis for ODO?
-Growth rate - fast growing and large
-Nutrition - Excess energy (P or Ca or Zn) excess Cu
-Heritability - stallion, multifactorial
-Trauma - normal stress on abnormal cartilage or vice versus
-exercise
Although OCD occurs in young patients it can become aparent in…
aged patients
Will you always be able to see an OCD fragment on radiographs?
No, if there is no cartilage in it, you will not see it
What are clinical signs of OCD?
Joint effusion, lameness (worse on flexion), synovial fluid cytologic changes
What are some diagnostics used to ID OCD?
Radiographs - effusion, prepurchase
Ultrasound, Contrast, CT, MRT
-Degenerative joint disease - varies by location, severity and if detached)
What are clinical signs of Subchondral bone cysts?
Effusion - fetlock, rare stifle, never in elbow
Lameness - training, OA
Where do SBC like to be?
In the middle of a bone
Stifle - medial trochlear ridge
Where does OCD like to be versus a subchondral cyst?
OCD: Gliding Joint
Cyst: Weight Baring Joint
How do you treat OCD and SBC?
Depen on joint involved and age of horse
-Young may heal with time but need to protect area
-Arthroscopy if making them lame
OCD: no OA then good prognosis, remove lose fragments, may tack cartilage
SBC: Asymptomatic, lame if communicate with joint, arthroscopic, 6-12month for final outcome
When should you go to surgery?
Clinical signs, occupation (race), potential of OA, Age (foal or weanling heal without surgery- up to 18 months)
What is the goal of medical therapy with this disease?
-Reduce trauma by exercise restriction
-Relieve synovitis, prevent DJD while healing (Adequan, Legend, Hyvisc, steroid)
What are the goals of arthroscopy?
Full exploratory of the joint, joint lavage, remove lose and free OC fragments, debride loose and diseased cartilage, no harm to normal or attached cartilage
What occurs post operative for OCD?
-Debride OCD bed heals with fibrocartilage
-Has different mechanical properties or resilience but better than loose bone
-Rehabilitation depend on severity of lesion
-Stall rest gradual return to exercise 60 days stall rest with no turn out
What are other surgical treatments for OA and SBC?
OCD: dart reattach chondral flap
SBC: inject cyst with steroid, screw across it, curette the syst, fill with bone substitute
What is SBC post op healing like?
Can be more painful right after - no good pain meds for bone, need longer rehabilitation
What does post op care after surgery look like?
Suture removal critical - send back to surgeon in 14 days - sterile gloves, scissors, prep skin, remove all and NO loop left behind, sterile bandage 2 days
-owner must call if increased swelling or discahrge
What is the prognosis?
OA decreases prognosis
Hock: DIRT = excellent
Stifle: LTR of Femur = Fair to good
Stifle: MRF Cyst = fair
Shoulder: OCD = Guarded
