Osteochondrosis Flashcards
What is endochondral ossification
Responsible for majority of skeletal growth during fetal development
Bones initially formed from cartilage & then replaced by bone
Centres of ossification expand via endochondral ossification at physis & AECC
Provides mechanism for growth while simultaneously allowing weight bearing
Occurs in 3 locations postnatally:
Physis/growth plate
Articular-epiphyseal cartilage complex (AECC)
Cuboidal bones
Endochondral ossification also occurs during healing of unstable fracture
Cell division in epiphyseal cartilage is stimulated by growth hormone (IGF-1)
Lack of IGF-1 causes dwarfism
Bones completely ossified at puberty
What are cartilage canals in endochondral ossification
Channels within cartilage in which cartilage is replaced by bone
As growth slows & layer of growth cartilage becomes thinner, cartilage canals undergo chondrification
What is osteochondrosis
Developmental skeletal disorder of unknown aetiology
Characterised by local failures of endochondral ossification
What causes osteochondrosis
Failure of vessels in cartilage canals -> chondronecrosis
Biomechanical forces – shearing
Molecular alterations in endochondral ossification
Genetic factors
What are the clinical signs of osteochondrosis
Joint effusion
Lameness
Clinical signs onset often associated with exercise/trauma
What are the most common sites of osteochondrosis in dogs & horses
Dogs:
Shoulder
Stifle
Elbow
Hock
Horse:
Tibiotarsal
Femoropatellar
Fetlock
What is the process of endochondral ossification
- Chondrocytes proliferate & secrete cartilage extracellular matrix
- Cartilage matrix calcifies
- Cartilage matrix is invaded by blood vessels
- Osteoclasts, bone marrow cells & osteoblasts are delivered to growth cartilage
- Osteoid is deposited on spicules of calcified cartilage matrix
- Primary spongiosum is replaced by woven bone
- Secondary spongiosum is replaced by lamellar bone
