Articular Cartilage

Question 1

What makes up the most and least of the mass of cartilage?

Answer 1

Most: water
Least: Cells
Collagen is second most; 95% Type II collagen

Question 2

What happens to the water content in articular cartilage with aging and arthritis?

Answer 2

Arthritis: water content increases

Normal aging: water content decreases

Question 3

What are the age related changes seen in articular cartilage?

Answer 3

increases in:
chondrocytes size
protein content
stiffness (passive glycation leads to increased stiffness of collagen)
increase in ratio of proteoglycan keratin sulfate to chondroitin sulfate

decrease in:
absolute number of cells (becomes hypocellular, despite the fact that individual chondrocytes are increasing in size)
water content (differentiates from osteoarthritis where water content actually increases)
solubility
proteoglycan size
elasticity

Question 4

What area of depth must be injured in cartilage to promote healing?

Answer 4

Down to the tidemark
Produces fibrocartilage (has Type I cartilage)

Question 5

How does the thickness of cartilage change with increased and decreased loads?

Answer 5

Thins with decreased loads, no change with increased load

Question 6

What contributes most to the ability of hyaline cartilage to attract water?

Answer 6

Aggrecan

Question 7

biochemical changes are common to both aging cartilage and osteoarthritic (OA) cartilage?

Answer 7

Decreased proteoglycan content