Equine Joint Disease Flashcards
What is osteochondrosis?
failure or endochondral ossification, which leads to ischemic necrosis of the epiphyseal cartilage due to interruption of cartilage canal blood supply
= chondronecrosis with necrotic, non-perfused cartilage canals
What is osteochondrosis manifesta?
progression of OC, which impedes mineralization or vascularization
What are 3 possible results from osteochondrosis manifesta?
- lesion surrounded by bone is replaced by fibrous tissue and undergoes membranous ossification
- sunbchondral cyst - weight bearing results in unfolding of cartilage (secondary to trauma)
- osteochondrosis dissecans (OCD) - rupture of overlying cartilage results in fissure formation (secondary to trauma)
What are 6 possible etiologies of OC?
- biochemical influences
- failure of vascularization
- nutrition - mineral (Ca, P) imbalances, CHO (aldehyde) levels
- hormonal factors
- growth rate
- genetics
multifactorial!
What 4 breeds are associated with developing OC? What signalment is associated?
- TB
- WB
- QH
- Draft horses
yearlings or at he start of training (2-3 y/o)
What is clinical sign is indicative of OC?
joint effusion - “boggy hocks” (bog spavin) –> NOT lame at this time, possible with larger fragments
- bilateral is COMMON
What is the most important diagnostic tool for OC?
radiographs
- lameness exam can be abbreviated based on clinical signs and signalment
What 4 joints are affected by OC in order of occurrence?
- tibiotarsal joint (hock) - distal internal ridge of the tibia (DIRT), lateral > medial
- femoropatellar joint (stifle) - lateral femoral trochlear ridge > medial
- metacarpophalangeal/metatarsophalagneal joints - dorsal sagittal ridge > dorsal P1 > plantar P1
- scapulohumeral joint - glenoid, humeral head
more distal
What are the 5 structures most commonly develop subchondral bone cysts as a result to OC?
- medial femoral condyle, phalanges**
- carpal bones, tibia
- distal radius, talus
- sesamoid bones (including NB)
- humerus
(may or may not affect joint)
How is OCD treated?
arthroscopic removal
- can only be managed conservatively with no effusion or lameness
What is the most common procedure done to treat subchondral bone cysts? What are 4 other options? What is not recommended?
surgical cyst debridement + intralesional corticosteroids (can be ultrasound-guided to avoid sx)
- bone scaffold implantation
- cartilage flap transplant
- regenerative therapies
- transcondylar screw
medical management - rarely effective (~30%)
In what timeframe of development/change is expected for OC? What does this mean for clients?
- STIFLE - can change for up to 9 months
- HOCK - can change for up to 6 months
- NOT a static lesion
> 1 year without signs is considered “safe”
What is osteoarthritis? What are 3 parts of its pathogenesis?
equine degenerative joint disease (DJD) affecting the articular cartilage and subchondral bone
- abnormal mechanical loads - abnormal load on normal cartilage or normal load on abnormal cartilage
- metabolic tissue failure due to catabolic processes overwhelming anabolic repair
- this leads to cartilage having little to no ability to repair itself since it depends on diffusion of synovial fluid for nutrients
What are the 2 most common causes of abnormal loads on cartilage of horses that lead to OA?
- athletic use
- poor conformation
Why is the quality of tissue repair slow and imperfect? What is the most common result of healing? What does this depend on?
cartilage is avascular and lacks growth factor stimulation - full thickness lesions do not heal and partial thickness lesions have negligible healing
poor adhesion with fibrocartilage
age, species, size, location –> young > old, weight-bearing > non-weight-bearing
What healing occurs when cartilage is gone?
fusion
- osteophyte and enthesophyte formation
What is the single greatest economic loss in the equine industry?
articular disorders
- joint replacement is not possible in horses
What are 4 signs of OA?
- loss of RoM and lameness
- joint effusion
- heard swelling around joint - advanced disease, periarticular new bone formation
- axial muscle soreness - back pain
What are 3 options for diagnosing OA?
- lameness exam - positive flexion, blocks
- radiographs +/- MRI, CT
- response to treatment
What are 6 radiographic features of OA?
- periarticular osteophytosis
- asymmetrical joint space thinning
- subchondral sclerosis
- subchondral lysis
- osteochondral bodies - disintegration of joint surfaces, fractured osteophytes
- advanced remodeling or ankylosis
What are the 4 goals when treating OA?
- decrease inflammation
- prevent further cartilage damage - fixing is not possible
- alleviate pain
- return to function
What are 6 systemic treatments for OA?
- NSAIDs
- hyaluronic acid
- polysulfated glycosaminoglycans
- pentosan (?)
- nutraceuticals
- osteoclast inhibitors
What are 7 local treatments for OA?
MEDICATIONS - corticosteroids, HA, polyacrylamide hydrogel (PSGAGs)
BIOLOGICS - IRAP, PRP, Pro-stride (IRAP + PRP), stem cell therapy
What is hyaluronic acid? What effect does it have? What is the typical treatment protocol?
component of synovial fluid and cartilage ECM
anti-inflammatory
Legend ($84/vial) - 40 mg IV (1 vial) weekly for 1-3 treatments