45- OCD

endochondral ossification

produces bone via cartilage intermediate → long bones

transition from cartilage to bone is tightly coupled with chondrocyte, osteoblast, and vascular differentiation

vascular invasion triggers ossification

pathophysiology

OCD results when endochondral ossification fails → bone does not form underneath a portion of cartilage

exact cause not understood → genetic predisposition, vascular insufficiency, repetitive microtrauma

articular cartilage not stable due to lack of support underneath

cartilage separates from the bone → flap or fragment

treatable, though prognosis dependent on which joint is affected

formation of lesion

defect created at distal aspect of epiphysial bone

defect filled with cartilage that never matured into bone

location of OCD

  1. shoulder → caudal aspect of humeral head → must pull back opposite leg to see on xray

  2. elbow → medial portion of humeral condyle

  3. stifle → lateral portion of femoral condyle

  4. hock → medial portion of distal tibia

signalment

young, large-breed dogs

acute or gradual lameness

often unilateral on presentation → actually is bilateral defects → radiograph both shoulders

differentials

ununited anconeal process

fragmented coronoid process

panosteitis

hypertrophic osteodystorphy

elbow incongruity/dysplasia

soft tissue injury

early stages

lesions on caudal aspect of humeral head

flattening of the subchondral bone of the caudal humeral head

no displaced cartilage flap = probably not lame

if ODP is not detected in shoulders

radiograph elbows

tap joints

arthroscopy → both shoulders, gold standard

ultrasound

treatment

conservative → if OCD not seen on rads

strict rest 2-3 weeks

NSAIDs

repeat radiographs if no resolution

after arthroscopy?

limit activity for 4-6 weeks

allow soft tissues to heal + fibrocartilage to form over defect

pain management and sedation

gradual return to normal activity

elbow OCD

medial portion of humeral condyle

pain on elbow extension and lateral rotation

R/O elbow dysplasia

tx: arthroscopic debridement

fair prog → can still get OA

stifle OCD

lateral portion of femoral condyle

pain on stifle extension

arhtroscopic debridement

fair prog → can still get OA

tarsal OCD

medial portion of distal tibia

pain with hock ROM

arhtroscopic debridement

guarded prog → will get OA after initial relief → develops quickly