Cartilage Pathology

White

In the young and at sites of maximal weight bearing

False

It merges with a periosteal surface lines by fibrous tissue that is continuous with the synovial membrane

Nutrients diffuse into the articular cartilage from the synovial fluid and subchondral vessels.

Type II collagen

• Superficial layers resist shearing forces (layers are being shifted relative to one another)
• Middle layers are involved in shock absorption
• Calcified cartilage attaches articular cartilage to bone by its irregular (interlocking) interfaces

The tidemark is the boundary between uncalcified articular cartilage and the calcified cartilage

Only when the subchondral bone or synovium (tissues around the joint) are involved

True - it is only affected by inflammation in the synovium, subchondral bone or growth cartilage

Trauma, joint instability, lubrication failure

Repetitive stress can damage both the matrix and chondrocytes, leading to inappropriate cellular responses, chondrocyte death and therefore a viscous cycle of injury - i.e. accumulation of micro damage

True - cartilage has a limited response to injury

• Fibrilation - this is when proteoglycans are lost, collagen fibres condense and fray
• Erosion - this is when there is damage but it does not penetrate the subchondral bone
• Ulceration - this is when the full thickness of cartilage is lost.  Areas of ulceration become filled with vascular fibrous tissue.

Eburnation

• Chondromalacia (softening)
• Erosion and fibrillation
• Ulceration

Bony outgrowth/spurs

DJD.  It is initiated by joint instability and/or inflammatory cytokines.

Radiography

Inflammatory disease - it is a fibrovascular and inflammatory tissue that arises in the synvoium and spreads over articular cartilage.

A group of lesions in young animals where there is focal or multifocal failure of endochondral ossification at the metaphyseal growth plate and articular-epiphyseal complex.  In small animal medicine it is a big cause of DJD in older animals.

• Osteochondrosis latens - this is the first lesion where there is necrosis of blood vessels in the epiphyseal cartilage of the articular-epiphyseal complex.  These are microscopic lesions.
• Osteochondrosis manifesta - when the ossification front reaches this area of necrosis and there is a grossly visible area of necrotic epiphyseal cartilage.
• Osteochondritis dissecans - when clefts can form in the osteochondrosis lesion of the AE complex.  The overlying cartilage fractures and flaps can form.

When a flap of articular cartilage breaks off during osteochondrosis and it 'lives' in the synovial fluid