Articular cartilage

Question 1

Describe the four major layers of articular cartilage

Answer 1

• superficial/ tangential zone: thin collagen fibrils parallel to surface, elongated chondrocytes, low proteoglycan and high water content
• middle/ transitional: collagen fibrils less organized, chondrocytes more rounded
• deep: high proteoglycan and low water concentration, collagen fibers vertical to joint surface, columnar chondrocytes
• calcified zone: area near the tidemark, separates hyaline cartilage from subchondral bone

Question 2

_____ are derived from mesenchymal cells, are metabolically active, and generate ECM

Answer 2

chondrocytes

Question 3

Hyaline cartilage is made up of primarily ___ collagen

Answer 3

type II

Question 4

Describe the movement of nutrients in hyaline cartilage

Answer 4

joint loading causes movement of water which facilitates diffusion of nutrients

Question 5

Describe normal changes in cartilage with aging

Answer 5

loss of water and proteoglycan content
fewer chondrocytes
more lysosomal enzymes
increased stiffness, decreased solubility

Question 6

Why does prolonged immobilization lead to degeneration of articular cartilage?

Answer 6

loss of normal nutritive transport via diffusion when fluid does not move

Question 7

Describe the effects of supeperficial articular cartilage injuries

Answer 7

does not cross tidemark

no vascular supply= no healing

Question 8

Describe the effects of deep articular cartilage injuries

Answer 8

penetration beyond tidemark–> hemorrhage, inflammation–> healing with fibrocartilage

Question 9

Describe findings in osteoarthritis

Answer 9

loss of articular cartilage–> sclerosis of subchondral bone
bone cysts and osteophytes

loss of proteoglycan content but increased water content

Question 10

Describe findings in RA

Answer 10

Cartilage destruction due to inflammation
hypertrophy of synovial lining (pannus) and joint effusions
periarticular erosions, joint subluxation, no osteophytes