Cartilage Facts

Question 1

What characteristic change appears in cartilage in late-stage osteoarthritis?

Answer 1

Clusters of chondrocytes

Question 2

key transcription factor involved in the differentiation of cells towards the cartilage lineage

Answer 2

sox-9

Question 3

age changes in articular cartilage include the following INCREASES (4)

Answer 3

• chondrocytes size
• protein content
• stiffness (passive glycation leads to increased stiffness of collagen)
• ratio of proteoglycan keratin sulfate to chondroitin sulfate

Question 4

age changes in articular cartilage include the following DECREASES (5)

Answer 4

• 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 5

Cartilage changes in osteoarthritis INCREASES (4)

Answer 5

• water content (as a result of the disruption in architecture of the matrix molecules…different than decreased water content seen with normal aging process)
• interleukin-1
• chondrocyte activity and proliferation (clusters)
• metalloproteinase levels
• cathepsins B and D levels

Question 6

Cartilage changes in osteoarthritis DECREASES (4)

Answer 6

proteoglycan quantity and size
quantity of collagen
cross-linking
modulus of elasticity

Question 7

aggrecan water facts

Answer 7

can associate with 50 times its weight in water

increases swelling pressure

Question 8

Moderate distance running has what effect on knee articular cartilage in asymptomatic
distance runners?

Answer 8

The knee adapts to exercise by increasing the
glycosaminoglycan (GAG) content

Question 9

During early arthritis, which collagen type is found to be increased?

Answer 9

Type X collagen

Increased local strains
above the threshold results in an increase of Col X mRNA expression

Question 10

structure of cartilage proteoglycans can be described as

Answer 10

multiple glycosaminoglycans bound to core protein, which is subsequently bound to hyaluronate via a link protein

Question 11

boundary lubrication

Answer 11

bearing surface is non-deformable

lubricant only partially separates surfaces

superficial zone proteins (lubricin)

Question 12

superficial zone protein

Answer 12

like lubricin this is a boundary lubricant in the superficial zone