Chapter 73: Osteochondrosis Flashcards
What percentage of all dogs presented for orthopedic problems are diagnosed with OCD?
What % of dogs presenting for ortho problems at under 1 year of age are diagnosed with OCD?
3.7% of ALL orthopedic dogs
9% of orthopedic dogs under 1 year.
Male dogs are more commonly affected with OCD at all locations except where?
Females are more common for OCD of the talus (tarsus).
In most long bones, growth plates (physes) contribute ____% of final bone length whereas epiphyses contribute approximately ____%?
Growth plates contribute MOST 75-80% of final bone length (IMPORTANT)
Epiphyses contribute approx. 20-25%
At what age does the medial aspect of humeral condyle (a center of ossification) fuse to the lateral condyle?
6 weeks
What is saltation and stasis?
Which bones of the dog are known to experience it?
In human children, short periods of active growth alternate with longer periods with no measurable growth.
Saltation is growth and stasis is obvious.
Saltatory growth has been demonstrated in the dog radius, ulna and tibia.
What is the Hueter-Volkmann law and what does it describe?
Growth is retarded by increased mechanical compression and accelerated by reduced loading.
This fits with studies in lambs where 90% of growth-plate related bone lengthening occurred while they were lying down and nearly none when standing.
What are the (4) zones of the physis?
Resting (epiphyseal side)
Proliferative
Hypertrophic
Mineralization
In the outer layer of the articular-epiphyseal complex, what does the presence of the tidemark indicate?
The tidemark is a microscopically visible line that represents the separation of the zone of calcified cartilage from the radial zone.
Emergence of the tidemark indicates that cartilage maturation is complete.
Olsson and Reiland described two types of OCD. Most of our understanding is based on study of Type 1 lesions.
What are the two types, and where are they found?
Type 1: Occurs at the center of the affected articular surface, away from vascular attachments.
- Sites include the caudal humeral head, medial humeral condyle, lateral and/or medial femoral condyles (IMPORTANT)
Type 2: Occurs at joint margin and retains vascular attachment.
- Sites include medial or lateral trochlear ridges of talus (which attach to joint capsule and/or ligaments) and MCP of ulna (which is vascularized through joint capsule or the annular ligament)
There is a grading scheme for OCD of the proximal humerus that grades from I to IV. What does a lesion of each type look like?
Type I: Cartilage surface normal, cartilage slightly thickened, miniscule subchondral bone defect
Type II: Cartilage surface mottled, more thickened, small “cleft” of subchondral bone
Type III: Discoid elevation of cartilage surface. Underlying bone sclerotic
Type IV: Typically a partially or fully detached flap and joint mice
What are the three stages of OCD?
Oseochondrosis Latens
Osteochondrosis Manifesta
Osteochondrosis/itis dissecans
Describe the lesion of osteochondrosis latens?
Early, microscopic
Describe the lesion of Osteochondrosis manifesta?
Subclinical lesion that is both macroscopically and radiologically apparent.
Describe the lesion of Osteochondrosis dissecans?
Why is this also called Osteochondritis, even though it isn’t inflammatory in pathology?
An attached or loose cartilage flap is present. These dogs are usually clinically affected.
Because the flap causes synovitis, this is often referred to conventionally as an -itis even if the pathology is not truly inflammatory.
What is the incidence of OCD in cats?
0.001%
There are only a few cases in the literature, considered very uncommon.
